J Clin Oncol, 2003 Nov 15, 21(22), 4239 - 47 Overcoming drug resistance in multiple myeloma: the emergence of therapeutic approaches to induce apoptosis; Yang HH et al.; Drug resistance remains a major clinical challenge for cancer treatment . Early studies suggested that overexpression of P-glycoprotein was a major contributor to the chemotherapy resistance of myeloma cells and other tumor cells . Attempts in several clinical studies to reverse multidrug resistance protein (MDR) by using MDR modulators have not yet generated promising results . Recently, the emerging knowledge about the importance of overcoming antiapoptosis and drug resistance in treating a variety of malignancies, including multiple myeloma (MM), raises new hope of improving the treatment outcome for patients with cancer . The therapeutic value of targeting therapies that aim to reverse the antiapoptotic process in MM cells has been explored in a number of experimental systems, and the results have been promising . The proteasome inhibitor PS-341 is a new specifically targeted proapoptotic therapy that has been tested in clinical studies . The results indicate that PS-341 alone is an effective therapy for patients with MM who experience disease relapse . Recent in vitro data also demonstrate that PS-341 can markedly sensitize chemotherapy-resistant MM cells to various chemotherapeutic agents . On the basis of these encouraging results, clinical studies are underway to test the efficacy of PS-341 and chemotherapeutic agents as combination therapy in treating patients with refractory and relapsed MM. Clin Cancer Res, 2003 Nov 1, 9(14), 5221 - 7 Phase I and pharmacokinetic trial of the novel taxane BMS-184476 administered as a 1-hour intravenous infusion in combination with cisplatin every 21 days; Sun W et al.; BMS-184476 is a 7-methylthiomethyl ether derivative of paclitaxel that displays potency superior to paclitaxel against tumor cells in culture and human tumor xenografts . It also inhibits the growth of paclitaxel-resistant human tumor cell lines with multidrug resistance mediated by either P-glycoprotein or mutated tubulin . Given the known synergy between taxanes and cisplatin in vitro and their clinical activity in combination, we performed a Phase I trial of BMS-184476 as a 1-h i.v . infusion followed by cisplatin every 21 days . Twenty-seven patients with a variety of solid tumors and good performance status received 116 cycles of therapy at BMS-184476 doses of 40-60 mg/m(2) together with cisplatin at 75 mg/m(2) . The early observation of hypersensitivity reactions required prophylactic premedication in all patients . At the planned highest dose of BMS-184476 (60 mg/m(2)) and cisplatin (75 mg/m(2)), we observed dose-limiting toxicity in the form of neutropenia and diarrhea . Also at this level, five patients experienced grade 3 or worse nausea and vomiting . Aggressive prophylactic treatment eliminated the gastrointestinal toxicity . Mild to moderate peripheral neuropathy was infrequent, as was alopecia . Patient benefits included three partial responses in patients with mesothelioma, esophageal cancer, and head and neck cancer, and two additional minor responses . Plasma pharmacokinetic data are available for 23 patients treated at 40-60 mg/m(2) . The mean maximum plasma concentrations and areas under the curves increased in a dose-related manner . The pharmacokinetics of BMS-184476 appeared independent of dose . The mean (+/- SE) values for clearance, volume of distribution at steady state, and the apparent terminal half-lives of the three dose groups during cycle 1 were 243 +/- 5 ml/min/m(2), 423 +/- 58 l/m(2), and 32.2 +/- 4.5 h, respectively . BMS-184476 60 at mg/m(2) with cisplatin at 75 mg/m(2) with appropriate supportive therapy is the dose recommended for further evaluation. Clin Cancer Res, 2003 Nov 1, 9(14), 5171 - 7 The role of breast cancer resistance protein in acute lymphoblastic leukemia; Plasschaert SL et al.; PURPOSE: Overexpression of the transporter ABCG2, also known as breast cancer resistance protein and mitoxantrone resistance protein, can confer resistance to a variety of cytostatic drugs, such as mitoxantrone, topotecan, doxorubicin, and daunorubicin . This study analyzes the ABCG2 expression and activity in 46 human de novo acute lymphoblastic leukemia B- and T-lineage (ALL) samples . EXPERIMENTAL DESIGN: ABCG2 expression was measured flow cytometrically with the BXP-34 monoclonal antibody . ABCG2 functional activity was determined flow cytometrically by measuring mitoxantrone accumulation in combination with the ABCG2 inhibitor fumitremorgin C (FTC) . To determine a possible effect of the transporters P-glycoprotein and multidrug resistance-associated protein (MRP1 and MRP2) on mitoxantrone accumulation, the accumulation was investigated in the presence of the P-glycoprotein inhibitor PSC 833 and MRP inhibitor MK-571 . The ABCG2 gene was sequenced to investigate the amino acid at position 482 . RESULTS: In B-lineage ALL (n = 23), the median BXP-34:IgG1 ratio was higher, namely 2.4 (range, 1.7-3.7), than in T-lineage ALL (n = 23; 1.9; range, 1.2-6.6; P = 0.003) . The addition of FTC to mitoxantrone treatment caused a median increase in mitoxantrone accumulation of 21% (range, 0-140%) in B-lineage ALL . In T-lineage ALL, this FTC effect was less pronounced (5%; range, 0-256%; P = 0.013) . The influence of FTC on mitoxantrone accumulation correlated with ABCG2 protein expression (r = 0.52; P < 0.001; n = 43) . The increase in mitoxantrone accumulation, when FTC was added to cells treated with both PSC 833 and MK-571, correlated with the ABCG2 expression in B-lineage ALL but not in T-lineage ALL . Sequencing the ABCG2 gene revealed no ABCG2 mutation at position 482 in patients who accumulated more rhodamine after FTC . CONCLUSIONS: This study shows that ABCG2 is expressed higher and functionally more active in B-lineage than in T-lineage ALL. Toxicol Appl Pharmacol, 2003 Nov 15, 193(1), 66 - 72 Endocrine disruptors induce cytochrome P450 by affecting transcriptional regulation via pregnane X receptor; Mikamo E et al.; Pregnane X receptor (PXR) is a nuclear receptor that regulates the expression of genes for cytochrome P450 3A (CYP3A), multidrug resistance 1 (MDR1), and organic anion-transporting peptide 2 (OATP2) . These genes control the metabolism (CYP3A subfamily) and aspects of the pharmacokinetics (MDR1 and OATP2) of both endogenous and xenobiotic compounds . Since PXR is important in understanding the actions of endocrine disruptors (EDs), we determined the ability of suspected EDs to interact with PXR . In our study, 7 of 54 xenobiotics compounds interacted with PXR, including methoxychlor and benzophenone . All of the chemicals activated PXR in vitro and induced CYP3A mRNA in the male rat liver . In addition, CYP2C11 was also induced by some PXR agonists and converted methoxychlor into xenoestrogen . These findings suggest that some EDs affect sex hormone receptor indirectly by induction of metabolic enzyme via PXR, to produce rapidly higher concentrations of effective metabolites, leading to disturbance of the endocrine system. Int J Oncol, 2003 Dec, 23(6), 1505 - 13 Voacamine, a bisindolic alkaloid from Peschiera fuchsiaefolia, enhances the cytotoxic effect of doxorubicin on multidrug-resistant tumor cells; Meschini S et al.; Multidrug-resistance (MDR) is largely caused by the efflux of therapeutics from the tumor cell by means of P-glycoprotein (P-gp), resulting in reduced efficacy of the chemotherapy . In order to overcome MDR, substances, such as verapamil and cyclosporin A (CsA), were employed . As these P-gp modulating agents did not seem promising in clinical practice, new compounds with a low degree of undesirable side effects, were introduced . In this study, bisindolic alkaloid voacamine was examined for its possible capability of enhancing the cytotoxic effect of doxorubicin (DOX) on drug resistant cells . Two different pairs of tumor cell lines were analyzed: the parental lymphoblastoid cell line CEM-WT and its MDR derivative CEM-R, the parental osteosarcoma cell line U-2 OS-WT and its resistant counterpart U-2 OS-R . These cell lines were characterized for their morphological features by scanning electron microscopy (SEM) and for the expression of the main drug transporters by flow cytometric analysis . The effects of voacamine on the cell survival and on both accumulation and efflux of DOX were then investigated . The intracellular distribution of DOX, given alone or in association with CsA or voacamine, was observed by laser scanning confocal microscopy . A differential effect of voacamine between sensitive and resistant cells on the intracellular DOX concentration and distribution was shown . In particular, voacamine induced a significant increase of drug retention and intranuclear location in resistant cells . The results of cell survival experiments revealed an enhancement of the cytotoxic effect of DOX induced by voacamine, confirmed by evident morphological changes observed by SEM . These findings suggest promising applications of this natural substance against MDR tumors. Cancer Res, 2003 Nov 1, 63(21), 7392 - 9 Lamellarin D: a novel potent inhibitor of topoisomerase I; Facompre M et al.; We report the identification and characterization of a novel potent inhibitor of DNA topoisomerase I: lamellarin D (LAM-D), initially isolated from a marine mollusk, Lamellaria sp., and subsequently identified from various ascidians . This alkaloid, which displays potent cytotoxic activities against multidrug-resistant tumor cell lines and is highly cytotoxic to prostate cancer cells, bears a 6H-{1}benzopyrano{4',3':4,5}pyrrolo{2,1-a}isoquinolin-one pentacyclic planar chromophore, whereas its synthetic 5,6-dehydro analogue, LAM-501, has a significantly tilted structure . DNA binding measurements by absorbance, fluorescence, and electric linear dichroism spectroscopy show that LAM-D is a weak DNA binder that intercalates between bp of the double helix . In contrast, the nonplanar analogue LAM-501 did not bind to DNA and failed to inhibit topoisomerase I . DNA intercalation may be required for the stabilization of topoisomerase I-DNA complexes by LAM-D . In the DNA relaxation assay, LAM-D strongly promoted the conversion of supercoiled DNA into nicked DNA in the presence of topoisomerase I . The marine product was approximately 5 times less efficient than camptothecin (CPT) at stabilizing topoisomerase I-DNA complexes, but interestingly, the two drugs exhibited slightly distinct sequence specificity profiles . Topoisomerase I-mediated DNA cleavage in the presence of LAM-D occurred at some sites common to CPT, but a few specific sites identified with CPT but not with LAM-D or conversely unique sites cleaved by LAM-D but not by CPT were detected . The distinct specificity profiles suggest that LAM-D and CPT interact differently with the topoisomerase I-DNA interface . A molecular modeling analysis provided structural information on the orientation of LAM-D within the topoisomerase I-DNA covalent complex . The marine alkaloid did not induce DNA cleavage by topoisomerase II . Immunoblotting experiments revealed that endogenous topoisomerase I was efficiently trapped on DNA by LAM-D in P388 and CEM leukemia cells . P388/CPT5 and CEM/C2 cell lines, both resistant to CPT and expressing a mutated top1 gene, were cross-resistant to LAM-D . Collectively, the results identify LAM-D as a novel lead candidate for the development of topoisomerase I-targeted antitumor agents. Cancer Res, 2003 Nov 1, 63(21), 7284 - 90 Glucose depletion enhances P-glycoprotein expression in hepatoma cells: role of endoplasmic reticulum stress response; Ledoux S et al.; P-Glycoprotein (P-gp) encoded by the MDR gene is one of the main factors in multidrug resistance . Its expression in cancer cells, which compromises cancer outcome, can be enhanced by some stress signals . Energy depletion, frequently observed in malignant cells, was shown to induce chemoresistance and could be one of these signals . To test this hypothesis, we studied the effect of glucose deprivation on P-gp expression in a rat hepatoma cell line (Fao) . Incubation of Fao cells with a glucose-free medium enhanced P-gp mRNA and protein expression in a time-dependent manner, up to 400% at 40 h . This effect was associated with a stimulation of {(3)H}vinblastine efflux by P-gp despite impaired glycosylation . It was reproduced by inducers of endoplasmic reticulum stress response, such as 2-deoxyglucose (DG), tunicamycin, and thapsigargin . P-gp mRNA induction by DG was preceded by an increase in activator protein binding activity, c-Jun expression, and phosphorylation . In contrast, nuclear factor-kappaB binding activity was unaffected by DG . The antioxidant N-acetylcysteine partially reversed the increase in P-gp mRNA and protein levels induced by DG, as well as the enhancement of c-Jun phosphorylation and activator protein binding activity . Finally, transient transfection of the cells with a deleted mutant of c-Jun, Tam 67, abolished the DG-induced P-gp mRNA expression and mdr1b promoter activation . In conclusion, glucose deprivation enhances P-gp expression and transport function in liver cancer cells . This effect is mediated by endoplasmic reticulum stress response and involves MDR transcriptional induction through c-Jun activation . These results emphasize the importance of glucose metabolism in chemoresistance. Am J Hum Genet, 2003 Dec, 73(6), 1282 - 92 Epub 2003 Nov 07. MDR1 Ala893 polymorphism is associated with inflammatory bowel disease; Brant SR et al.; Crohn disease (CD) and ulcerative colitis (UC) are overlapping chronic inflammatory bowel diseases (IBDs) . Suggestive evidence for linkage at chromosome 7q has been reported for both CD and UC . Contained within this region is the gene for MDR1 (multidrug resistance), a membrane transport protein for which human polymorphisms have been reported in Ala893Ser/Thr and C3435T that alter pharmacokinetic profiles for a variety of drugs . Because mdr1 knockout mice spontaneously develop colitis, exonic regions were resequenced and tested for IBD association in a large, multicenter North American cohort . Two missense mutations, Asn21Asp and Ala893Ser/Thr, as well as the expression-associated polymorphism C3435T, described elsewhere, were genotyped in the entire cohort . Significant association of Ala893 with IBD was observed by both case-control analysis (P=.002) and the pedigree disequilibrium test (PDT {P=.00020-.00030}) but not for the Asn21Asp or C3435T polymorphisms . Significant association by PDT was observed within the subset with CD (P=.0014-.00090), with similar, nonsignificant trends in a smaller subset with UC . The Ala893Ser/Thr variant is triallelic, and the associated, common allele is Ala893, with undertransmission of the 893Ser (common) and the 893Thr (rare) variants . The Ala893 variant has decreased activity compared with the 893Ser variant; therefore, the association with human IBD is consistent with the murine model of mdr1 deficiency . Taken together, these data support the association of the common Ala893 polymorphism with IBD specifically and, more broadly, provides additional support for its contribution to interindividual pharmacogenetic variation. Exp Brain Res, 2003 Dec, 153(3), 356 - 65 Epub 2003 Sep 12. Modulation of transendothelial permeability and expression of ATP-binding cassette transporters in cultured brain capillary endothelial cells by astrocytic factors and cell-culture conditions; Torok M et al.; Confluent cell monolayers of brain capillary endothelial cells (BCEC) are used widely as an in vitro cell culture model of the blood-brain barrier . The present study describes the influence of cell-culture conditions on tight junctions, filamentous-actin cytoskeleton, and expression of ATP-binding cassette (ABC) transporters in primary cell cultures of porcine BCEC . Astrocyte as well as C6 glioma-conditioned cell culture medium was used in combination with retinoic acid, dexamethasone, cyclic adenosine monophosphate (cAMP) analogs, or 1,25-dihydroxyvitamin D3 . It was shown that C6-conditioned medium led to a reorganization of filamentous actin and to an improved staining of zonula occludens-associated protein-1 (ZO-1) . Further optimization of these culture conditions was achieved with cAMP analogs and dexamethasone . Retinoic acid, as well as 1,25-dihydroxyvitamin D3, did not improve cellular tight junctions as judged by filamentous actin, ZO-1 rearrangement, and transcellular electrical resistance (TER) measurements . However, these morphological changes did not influence the paracellular permeability of the extracellular marker sucrose . Expression of ABC transporters such as P-glycoprotein, multidrug resistance-associated protein-1(MRP1), and MRP2 were compared by measuring messenger RNA (mRNA) levels in whole-brain tissue, isolated brain capillaries, and cultured cells . In freshly isolated BCEC, mRNA levels of MRP2 and P-glycoprotein dropped by two- to sevenfold, respectively, whereas MRP1 mRNA levels were slightly increased . During cell culture, mRNA levels of MRP1 and MRP2 decreased by up to fivefold, while P-glycoprotein levels remained constant . These results were unaltered by different cell-culture conditions . In conclusion, the present study suggests that paracellular permeability, as well as mRNA expression of the studied ABC transporters in primary cultures, of porcine BCEC are insensitive toward changes in cell-culture conditions. Tumour Biol, 2003 May-Jun, 24(3), 151 - 5 Technetium-99m tetrofosmin SPECT predicts chemotherapy response in small cell lung cancer; Yeh JJ et al.; The multidrug resistance gene 1 encoding human P-glycoprotein (Pgp) is thought to play an important role in the multidrug resistance of lung cancer . The purpose of this study was to predict chemotherapy response by technetium-99m tetrofosmin (Tc-99m TF) lung single photon emission computed tomography (SPECT) and compare Pgp expression in patients with untreated small cell lung cancer (SCLC) . Forty patients with untreated SCLC received Tc-99m TF lung SPECT prior to chemotherapy . The chemotherapy response was evaluated in the 3rd month after completion of treatment . Immunohistochemical staining of Pgp expression was performed on multiple nonconsecutive sections of biopsy specimens . By quantitative analyses, tumor to background ratios were 1.86 +/- 0.27 and 1.17 +/- 0.26 for patients with a good and poor response, respectively (p < 0.05) . All of the 20 patients with a good chemotherapy response also had a positive Tc-99m TF lung SPECT and negative Pgp expression . In contrast, only 4 of the 20 patients with a poor chemotherapy response had a positive Tc-99m TF lung SPECT . Moreover, 10 of the 20 patients with a poor chemotherapy response also had negative Pgp expression (p < 0.05) . Therefore, we concluded that Tc-99m TF lung SPECT can accurately predict the chemotherapy response, and Tc-99m TF lung SPECT findings can be partially compatible with Pgp expression in patients with untreated SCLC . Srp Arh Celok Lek, 2003 Mar-Apr, 131(3-4), 168 - 72 {Knowledge level of students at the Kragujevac Medical School about nosocomial infections}; Ilic M et al.; OBJECTIVE: To investigate differences in clinical and pre-clinical medical students' knowledge of nosocomial infections (NI) . DESIGN: Cross-sectional survey . RESULTS: Questionnaires was answered and returned by 352 of 453 student (77.7%) . The results indicated that students knew the definition of NI (70.1% correct answers) and their reservoirs (86%) . The bacteria as etiological agents was the most frequent answer (76.4%), but 30.9% students did not knew at least one multidrug-resistant bacteria . About one half of the students (54.4%) knew that contact was the most frequent mode of NI transmission, but hand washing as preventive measure was cited by only 18.8% of students . Significantly statistical differences about NI in our country, etiology NI and preventive measures, and perception of risk for transmission of hepatitis B for health-care personnel were founded by year of training, by expectation that final-year medical students as more successfully, while pre-clinical students knew more about mode of NI transmission . Pre-clinical students who had previously finished nursing school knew more about multidrug-resistant bacteria than those who had finished some other secondary school, but showed a lower knowledge about definition and most important preventive measures of NI . Clinical students who had previously finished nursing school knew more about frequency NI in our country, reservoirs and preventive measures of NI than those who had finished some other secondary school . CONCLUSION: Data support the need for additional information about nosocomial infections, especially practical work in prevention, in order to get complete knowledge about nosocomial infections. Int J Lepr Other Mycobact Dis, 2003 Sep, 71(3), 240 - 3 A second case of multidrug-resistant Mycobacterium leprae isolated from a Japanese patient with relapsed lepromatous leprosy; Matsuoka M et al.; Emergence of drug resistant strains of Mycobacterium leprae was reported soon after the introduction of dapsone (diamino-diphenyl sulphone, DDS) for leprosy treatment (6, 10, 11) . Three cases of multidrug-resistant strains of M . leprae have been reported recently (2, 8, 9, 13) . In order to prevent multiple drug resistant strains of M . leprae from developing, current leprosy control strategies are based on early detection of cases and treatment with multidrug therapy (MDT) as recommended by the World Health Organization (WHO) . We report here the identification of a multidrug-resistant strain of M . leprae from a patient who received inadequate therapy for leprosy . The drug resistant profile of the isolated strain was confirmed by the mouse footpad method and the identification of mutations in genes previously shown to be associated with resistance to each drug was made. Am J Infect Control, 2003 Oct, 31(6), 354 - 6 Do physicians examine patients in contact isolation less frequently? A brief report; Saint S et al.; BACKGROUND: Patients who are hospitalized and infected with multidrug-resistant bacteria are usually placed in contact isolation, which requires hospital personnel to gown and glove before patient examination . Contact isolation with active culture surveillance appears beneficial in preventing the spread of drug-resistant infections; however, contact isolation may impede the ability to examine patients as a result of the additional effort required to gown and glove . We assessed whether patients who are hospitalized and placed under contact precautions are examined less often by second- and third-year medical residents (ie, senior medical residents), and attending physicians during morning rounds . METHOD: We conducted a prospective cohort study on the inpatient medical services at 2 university-affiliated medical centers . We directly observed senior medical residents and attending physicians during morning rounds, and recorded the contact precaution status of the patient and whether they were examined by either physician . RESULTS: Of a total of 139 patients, 31 (22%) were in contact isolation . Senior medical residents examined 26 of 31 patients (84%) in contact isolation versus 94 of 108 patients (87%) not in contact isolation (relative risk, 0.96; 95% confidence interval, 0.81-1.14; P =.58) . In comparison, attending physicians examined 11 of 31 patients (35%) in contact isolation versus 79 of 108 patients (73%) not in contact isolation (relative risk, 0.49; 95% confidence interval, 0.30-0.79; P <.001) . DISCUSSION: Attending physicians are about half as likely to examine patients in contact isolation compared with patients not in contact isolation. Bioorg Med Chem, 2003 Nov 17, 11(23), 5221 - 7 Modified jatrophane diterpenes as modulators of multidrug resistance from Euphorbia dendroides L; Corea G et al.; The new diterpenoids terracinolides J-L (1-3), 13alpha-OH terracinolide F (8), abeodendroidin F (11) and epiabeodendroidin F (12) have been identified from Euphorbia dendroides L . The new compounds and six co-occurring known terracinolides were tested as inhibitors of the drug-efflux activity of P-glycoprotein from cancer cells . The results were used to extend the structure-activity relationships established for this class of compounds highlighting the relevance of substitution at positions 2, 3, 6, and 15 and disclosing a remarkable tolerance toward connectivity changes in the terpenoid core. J Indian Med Assoc, 2003 Mar, 101(3), 210 - 2 Ofloxacin in multidrug resistant tuberculosis; Walwaikar PP et al.; Tuberculosis (TB) is the leading infectious cause of death today and 3.81 million cases occurred in 1997 and 1998 . Even today in spite of having four drugs like isoniazid, rifampicin, streptomycin/pyrazinamide and ethambutol for the intensive phase, the total duration of treatment remains six months . Because of the global health problems of TB, the increasing rate of multidrug resistant TB (MDR-TB) and the high rate of co-infection with HIV, the need for effective non-toxic antituberculous agents is essential . Fluoroquinolones have been classified as drugs having low bactericidal activity by the WHO . To date, they have been used for preventive therapy, empirical treatment of patients with TB and retreatment of patients with relapsing TB . In-vitro and in-vivo clinical studies have identified ofloxacin as a promising new agent in the treatment of MDR-TB . Ofloxacin has been advocated by the WHO in case of MDR-TB, when susceptibility to test results are not available before starting the new treatment, in the continuation period (18 months) and if resistance is proven to at least isoniazid and rifampicin. J Indian Med Assoc . 2003 Mar;101(3):190, 192, 194 passim. Tuberculosis--triumph and tragedy; Singh MM; Tuberculosis has been making havoc worldwide with an 11.9 million cases to be involved by the year 2005 . In India, about 2 million cases are infected every year . Regarding triumphs and tragedies in the control of tuberculosis some points as follows are discussed . (1) Tuberculosis Control Programmes from National Tuberculosis Programme (NTP) to Revised National Tuberculosis Control Programme (RNTCP) and Directly Observed Treatment, Short course (DOTS) . (2) Problem of multidrug resistance (MDR) tuberculosis and (3) HIV and tuberculosis . DOTS being largely based on Indian research . It is now being applied worldwide . MDR is strictly a man made problem . Poor prescriptions, poor case management, lack of coordinated education and haphazard treatment research result in drug resistance . Treatment of MDR is difficult . The drug acceptability, tolerance and toxicity have to be considered . HIV and tuberculosis form a deadly duo . They mean more cases, more costs and more national losses. J Indian Med Assoc, 2003 Mar, 101(3), 157 - 8, 166 Scientific basis of directly observed treatment, short-course (DOTS); Sharma SK et al.; The introduction of rifampicin, pyrazinamide and ethambutol ushered in the era of "short course chemotherapy" . Multidrug resistance TB (MDR-TB) is threatening to destabilise the best efforts of TB control . Treatment of MDR-TB is difficult, expensive and toxic and is often unsuccessful . DOTS is an interventional strategy designed to effectively diagnose and treat TB . The fundamental principles in the DOTS strategy are: Polititical will, diagnosis by sputum microscopy, directly observed standardised short-course treatment, adequate supply of good quality drugs, systematic monitoring and accountability . Patients with HIV infection and TB disease respond well to antituberculosis treatment if they are given short-course chemotherapy in the programme of DOTS. J Indian Med Assoc, 2003 Mar, 101(3), 154 - 6 Status of drug resistance in tuberculosis after the introduction of rifampicin in India; Paramasivan CN; The current threat in tuberculosis treatment lies on the fact of emergence of strains resistant to two most antituberculous drugs, isoniazid and rifampicin . Drug resistance to TB may be classified as primary and acquired . Causes of drug resistance are inefficient administration of effective treatment, poor case handling, use of sub-standard drugs, ignorance of healthcare workers, etc . Multidrug resistant TB (MDR-TB) prevalence (median) in new case is highest (14.1%) in Estonia . Studies undertaken in different regions in India by Tuberculosis Research Centre (TRC) during 1997-2000 revealed acquired MDR-TB resistance levels of 25-100% . The key to successful prevention of the emergence of drug resistance remains adequate case finding, prompt and correct diagnosis and effective treatment of infective patients. J Indian Med Assoc, 2003 Mar, 101(3), 140 - 1, 147 Good progress with DOTS in the South-East Asia Region; Nair N et al.; The South-East Asia Region (SEAR) accounts for 38% of the global tuberculosis (TB) . Encouraging progress has been made since the DOTS strategy was introduced in all SEAR Member States between 1993-94 . Operational guidelines for and joint plans of action for disease control activities in the border districts of Bangladesh, Bhutan, India and Nepal have been drawn up . The key issues involved in the good progress with DOTS are: Resource mobilisation, case detection, case management, drugs and logistics, supervision, monitoring and surveillance, preventing emergence of multidrug resistant TB and lastly health sector reform . Given the current momentum and commitment, it is expected that the region will active the set targets of universal coverage by 2006. Trop Gastroenterol, 2003 Apr-Jun, 24(2), 70 - 2 The epidemiological and resistogram patterns of enteropathogenic and enterotoxigenic Escherichia coli isolated from diarrhoeal stools in a north Indian hospital; Vaishnavi C et al.; We report our findings on the epidemiological and resistogram patterns of enteropathogenic Escherichia coli (E . coli) (EPEC) and enterotoxigenic E . coli (ETEC) in patients with diarrhoea in a north Indian hospital . A total of 153 diarrhoeic stool samples were cultured for E . coli . Pure or predominant growth obtained was biochemically identified, serogrouped and tested for antibiotic susceptibility . Among the E . coli that could be serogrouped, there were 7 EPEC and 11 ETEC isolates, most of which were multidrug resistant . Apart from this, there were 35 untypable and 4 rough strains of E . coli . Culturing stools and testing the antibiotic susceptibility for most categories of diarrhoeagenic E . coli should be performed in cases of persistent diarrhoea and during outbreaks . This will help to study its epidemiological pattern in a particular locale . Moreover, this information coupled with the clinical picture may be valuable in deciding the need for and type of antibiotic therapy. J Pharm Sci, 2003 Nov, 92(11), 2152 - 63 Cytokines alter the expression and activity of the multidrug resistance transporters in human hepatoma cell lines; analysis using RT-PCR and cDNA microarrays; Lee G et al.; Pro-inflammatory cytokines suppress the hepatic expression of the multidrug resistance transporters in rodents, indicating potential usefulness in chemotherapy . Our objective was to investigate their impact in human hepatoma cells . HuH 7 and HepG2 cells were treated with IL-1beta, IL-6, or TNF-alpha for 0-72 h . Expression and activity of MDR1 and the MRP (MRP1, 2, 3, and 6) transporters were examined by RT-PCR, efflux assays, and microarrays . Significant reductions in the MDR1-mediated efflux of Rhodamine 123 and MDR1 mRNA levels were observed in HuH 7 cells treated with IL-6, TNF-alpha, or IL-1beta and in TNF-alpha-treated HepG2 cells . However, cytokine-treated HuH7 cells also demonstrated 1.6- to 2.6-fold greater efflux of the MRP substrate, 5-carboxyfluorescein (5-CF) and higher MRP3 mRNA levels (p < 0.05) . IL-1beta and IL-6 treatments increased MRP activity and MRP1 mRNA levels in HepG2 cells (p < 0.05) . Microarrays studies performed in IL-6 and TNF-alpha-treated HepG2 cells detected similar changes in the expression of the MDR1 and MRP transporters, but this did not reach significance . However, the microarrays confirmed cytokine-mediated induction of several acute phase proteins . Our data suggests that although cytokine-mediated suppression of PGP may alter drug resistance in malignant cells, these cytokines may also impose an induction in other multidrug resistance genes . Hepatobiliary Pancreat Dis Int, 2003 Aug, 2(3), 397 - 403 Clinical significance of mrp gene in primary hepatocellular carcinoma; Wang BL et al.; OBJECTIVE: To study the relations among the expression of the multidrug resistance associated-protein (mrp) gene and clinicopathologic features, the influence of alpha-fetoprotein (AFP), and prognosis of patients who received adjuvant chemotherapy after resection of primary hepatocellular carcinoma (HCC) . METHODS: The expression of the mrp gene encoding MRP and mRNAmrp was determined in tissues from 54 untreated patients with HCC, adjacent tissues from 24 patients with HCC and archival paraffin-embedded tissues from 12 patients with posthepatic cirrhosis . The relationship between the mrp gene expression and the change level of AFP was analyzed in the 24 postoperative HCC patients whose AFP level was measured after 2 weeks . All of the HCC patients were followed up . RESULTS: The percentage of positive expressions of MRP and mRNAmrp in the three kinds of tissues was 57.40%, 25.00%, 16.67%, and 72.22%, 37.50%, 33.33% respectively . Significant difference was noted in the untreated HCC tissue, compared to the other two tissues (P<0.05) . No difference existed between the mrp gene expression and such clinicopathologic findings, as age, sex, and tumor size (P> 0.05), but the expression was related to the degree of differentiation of HCC (P<0.05) . The effective rate of AFP in the mrp gene positive expression group or postoperative chemotherapeutic patients was lower than that in the negative group (P<0.05) . Although no difference was seen in the 1-, 3-, 5-year survival rates of HCC patients (P>0.05), the mean survival time of postoperative HCC patients or the negative mrp gene expression group was longer than that of the positive group (P<0.05) . CONCLUSIONS: Multidrug resistance (MDR) of HCC is related to mrp gene expression and initiates the intrinsic MDR . Detection of mrp gene expression is of great significance in accessing chemotherapeutic resistance of HCC, which provides evidence for reversing MDR in HCC . The mrp gene may be a useful marker in detecting prognosis of HCC patients because its expression is correlated with tumor differention and mean survival time of the patients. Int J Tuberc Lung Dis, 2003 Nov, 7(11), 1104 - 8 Characterization of clinical isolates of Mycobacterium tuberculosis resistant to drugs and detection of RpoB mutation in multidrug-resistant tuberculosis in the Philippines; Agdamag DM et al.; SETTING: Retrospective study of Mycobacterium tuberculosis isolates at the STD/AIDS Cooperative Central Laboratory, Philippines . OBJECTIVE: To describe patterns of M . tuberculosis resistance against first-line anti-tuberculosis drugs, and to analyze the rpoB gene codon mutation of rifampicin (RMP) resistant isolates and correlate genotypic and phenotypic patterns . DESIGN: One hundred and sixty-four M . tuberculosis complex isolates were retrieved for phenotypic analysis; 89 were resistant to any anti-tuberculosis drug and 50 were RMP-resistant, whereas 48 were multidrug-resistant (MDR) . Of these 48, only 33 were available for genotypic analysis of the rpoB gene . RESULTS: Most drug-resistant isolates were phenotypically resistant to isoniazid (INH) (93%), and the probability of an RMP-resistant isolate becoming MDR was 96% . In 33 MDR isolates, 13 types of mutations in nine independent codons were identified; the most frequently mutated codons were S531L (61%) and G510H (15%), which were present in 76% (25/33) of the isolates . S531L was noted in 85.7% of the RMP + INH + SM resistant isolates, while only 80% of the isolates with INH + RMP, EMB + SM resistance showed this mutation . CONCLUSION: The high probability of RMP isolates being MDR suggests that genetic analysis of RMP resistance is useful in detecting MDR-TB . Worldwide accumulation of findings on circulating MDR-TB strains provides indispensable information about the re-emergence of TB. Int J Tuberc Lung Dis, 2003 Nov, 7(11), 1097 - 103 Prevalence of Beijing genotype in Latvian multidrug-resistant Mycobacterium tuberculosis isolates; Tracevska T et al.; SETTING: Predominant genotypes of Mycobacterium tuberculosis include the Beijing family, which has caused large tuberculosis outbreaks and has been associated with increased virulence and multidrug resistance (MDR) . OBJECTIVE: To search for the Beijing genotype among Latvian MDR patients to characterise their DNA isolates at the molecular level . DESIGN: MDR isolates were spoligotyped and tested for gene mutations by automatic nucleotide sequencing . RESULTS: Of 109 isolates examined, 95 were located in six clusters of 2 to 63 isolates each . The 63 isolates in the largest cluster had an identical pattern corresponding to the Beijing genotype . The remaining isolates were of a non-Beijing genotype and formed another large group whose similarity ranged from 72% to 100% . Mutations in the rpoB and katG genes were compared in the Beijing and non-Beijing strains . In both groups, the rpoB gene mutations predominated in codons S531L (52.2%) and D516V (14.7%) . Double mutations in the rpoB gene were observed in 8.2% of the isolates, most of them located among Beijing-type isolates . The katG gene mutation S315T (98.4%) was prevalent among all isolates . CONCLUSION: Molecular analysis of MDR isolates of M . tuberculosis demonstrates that the Beijing genotype, most likely due to recent transmission, is prevalent in Latvia among MDR patients and that this genotype can be associated with double mutations. Int J Tuberc Lung Dis, 2003 Nov, 7(11), 1045 - 51 Encouraging outcomes in the first year of a TB control demonstration program: Orel Oblast, Russia; Kherosheva T et al.; SETTING: Orel, Russia . OBJECTIVE: To evaluate outcomes of tuberculosis (TB) patients treated in the first year of a TB control demonstration project using a revised strategy of directly observed treatment, short-course (DOTS) . Standard methods recommended by World Health Organization (WHO) were adapted to include mycobacterial cultures . DESIGN: Retrospective cohort analysis of TB patients diagnosed between October 1999 and September 2000 . RESULTS: Among 749 TB patients, 65% had bacteriologic confirmation of pulmonary TB, 31% were diagnosed clinically, and 4% had extra-pulmonary TB . Most (92%) had no previous TB treatment, but 8% were identified as retreatment cases . Of all patients, 41% had new sputum smear-positive TB . No patients were HIV-infected . Multidrug-resistant (MDR) TB levels were 3% among new and 17% among retreatment patients . Among new smear-positive patients, treatment success was 79% (72% cure, 7% completion); remaining outcomes were 8% failure, 3% default, 8% death, and 1% transfer . Success rates for new culture-positive and clinically diagnosed patients were 81% and 91%, respectively . CONCLUSION: Despite historical differences, successful implementation of the revised TB strategy in Russia is possible . Treatment success rates were high, suggesting WHO targets of 85% cure for smear-positive patients is attainable . Obstacles include drug resistance and elevated death rates among smear-positive patients. Probl Tuberk Bolezn Legk, 2003, (9), 29 - 31 {The specific features of a pathogen in acutely progressive pulmonary tuberculosis}; Balasaniants GS et al.; Examination of 318 patients with different forms of acutely progressive pulmonary tuberculosis (APPT) revealed massive bacterial isolation in 181 patients of them . In one fourth of the patients, Mycobacterium tuberculosis (MBT) colonies grew during a month; the mean growth duration was 38.3 +/- 12.7 days, which was indicative of the viability of Mycobacteria and of their high virulence if they were isolated in large amounts . A hundred and thirty-three patients were found to be drug-resistant, which is one of the characteristics of present-day APPT . Such patients more frequently developed multidrug resistance . Sixty-three patients were ascertained to have secondary drug resistance, of them 41 patients were found to have drug resistance that progressed during APPT therapy. Probl Tuberk Bolezn Legk, 2003, (9), 6 - 9 {Causes and factors of development of drug resistance in pulmonary tuberculosis}; Nechaeva OB et al.; To prevent secondary multidrug resistance and polyresistance of Mycobacterium tuberculosis (MBT), it is necessary to strictly observe the tested chemotherapy regimens during intensive care by using at least four essential antituberculous drugs (ATD) mainly in combination . The rehabilitative phase should be monitored at outpatient units of a day hospital . To prevent cross MBT infection with drug resistance to essential ATD and to efficiently use expensive reserve drugs, it is necessary to set up specialized inpatient units (wards) for treatment and rooms for outpatient receipt of patients who isolate drug-resistant MBT strains. J Exp Zoolog A Comp Exp Biol, 2003 Nov 1, 300(1), 91 - 7 The xenobiotic transporter, MRP2, in epithelia from insects, sharks, and the human breast: implications for health and disease; Karnaky KJ Jr et al.; A large number of mechanisms, including special excretory transporters, have evolved to help organisms excrete deleterious xenobiotics and endogenous molecules . We have examined the xenobiotic transport function of a putative multidrug resistance associated protein, MRP2, in three different epithelia: the insect renal (Malpighian) tubules, the secretory tubule of the shark rectal gland, and in ductules of the human breast . In the case of the insect and shark, transporter activity occurs in epithelia capable of great fluid transport . In the case of the insect Malpighian tubule, understanding the underlying mechanisms of this transporter may help with efforts to control populations of disease-carrying agriculturally important insects . In striking contrast, ductule architecture in nonlactating human breast ductules is that of an epithelium with a closed lumen . Immunocytochemical studies show that MRP2 is localized in the apical region of the ductule epithelial cells . In this unique case, MRP2 substrates transported into the lumen could possibly be concentrated . Transport substrates of MRP2 include carcinogens as well as antioxidants and other salutary molecules . Thus, in the breast ductule, MRP2 may play a significant role in breast epithelial cell health and cancer carcinogenesis . FEBS Lett, 2003 Nov 6, 554(1-2), 23 - 9 Differential sensitivity of plant and yeast MRP (ABCC)-mediated organic anion transport processes towards sulfonylureas; Forestier C et al.; The role of ATP-binding cassette (ABC) proteins such as multidrug resistance-associated proteins (MRPs) is critical in drug resistance in cancer cells and in plant detoxification processes . Due to broad substrate spectra, specific modulators of these proteins are still lacking . Sulfonylureas such as glibenclamide are used to treat non-insulin-dependent diabetes since they bind to the sulfonylurea receptor . Glibenclamide also inhibits the cystic fibrosis transmembrane conductance regulator, p-glycoprotein in animals and guard cell ion channels in plants . To investigate whether this compound is a more general blocker of ABC transporters the sensitivity of ABC-type transport processes across the vacuolar membrane of plants and yeast towards glibenclamide was evaluated . Glibenclamide inhibits the ATP-dependent uptake of beta-estradiol 17-(beta-D-glucuronide), lucifer yellow CH, and (2',7'-bis-(2-carboxyethyl)-5-(and-6-)carboxyfluorescein . Transport of glutathione conjugates into plant but not into yeast vacuoles was drastically reduced by glibenclamide . Thus, irrespective of the homologies between plant, yeast and animal MRP transporters, specific features of plant vacuolar MRPs with regard to sensitivity towards sulfonylureas exist . Glibenclamide could be a useful tool to trap anionic fluorescent indicator dyes in the cytosol. Mem Inst Oswaldo Cruz, 2003 Sep, 98(6), 827 - 30 Epub 2003 Oct 29. Evaluation of indirect susceptibility testing of Mycobacterium tuberculosis to the first- and second-line, and alternative drugs by the newer MB/BacT system; Barreto AM et al.; In order to evaluate the Organon Teknika MB/BacT system used for testing indirect susceptibility to the alternative drugs ofloxacin (OFLO), amikacin (AMI), and rifabutin (RIF), and to the usual drugs of standard treatment regimes such as rifampin (RMP), isoniazid (INH), pyrazinamide (PZA), streptomycin (SM), ethambutol (EMB), and ethionamide (ETH), cultures of clinical specimens from 117 patients with pulmonary tuberculosis under multidrug-resistant investigation, admitted sequentially for examination from 2001 to 2002, were studied . Fifty of the Mycobacterium tuberculosis cultures were inoculated into the gold-standard BACTEC 460 TB (Becton Dickinson) for studying resistance to AMI, RIF, and OFLO, and the remaining 67 were inoculated into Lowenstein Jensen (LJ) medium (the gold standard currently used in Brazil) for studying resistance to RMP, INH, PZA, SM, EMB, and ETH . We observed 100% sensitivity for AMI (80.8-100), RIF (80.8-100), and OFLO (78.1-100); and 100% specificity for AMI (85.4-100), RIF (85.4-100), and OFLO (86.7-100) compared to the BACTEC system . Comparing the results obtained in LJ we observed 100% sensitivity for RMP (80-100), followed by INH-95% (81.8-99.1), EMB-94.7% (71.9-99.7), and 100% specificity for all drugs tested except for PZA-98.3 (89.5-99.9) at 95% confidence interval . The results showed a high level of accuracy and demonstrated that the fully automated, non-radiometric MB/BacT system is indicated for routine use in susceptibility testing in public health laboratories. Best Pract Res Clin Haematol, 2003 Dec, 16(4), 629 - 44 Immunophenotyping as a guide for targeted therapy; Sonneveld P et al.; Immunophenotyping of acute and chronic leukaemias has revealed many lineage- and differentiation-specific antigens . It has now become possible to classify leukaemias according to their unique antigenic expression pattern . Among many lineage- and differentiation-specific antigens, disease-specific antigens are increasingly recognized because of their specific prognostic or therapeutic relevance . Expression of the multidrug resistance proteins of the ABC transporter family is associated with a poor response to treatment and a grave clinical prognosis . Recently, attempts to reverse refractory disease by using P-glycoprotein inhibitors have been performed in acute myeloid leukaemia, so far without evidence of clinical benefit.Other new leads to use antigen expression as a way of designing tumour-specific therapy have resulted in imatinib and Flt3 inhibitors which target tyrosine kinases in the leukaemic cell . Clinical trials are underway to investigate the effect of these new agents . The development of an antibody-calicheamycin complex directed against the myeloid-specific antigen CD33 has shown clinical activity in patients with relapsed acute myeloid leukaemia . The further development of these approaches is discussed. Best Pract Res Clin Haematol, 2003 Dec, 16(4), 613 - 28 The prognostic significance of antigen expression in leukaemia; Schabath R et al.; Numerous immunophenotypic features have been examined for their potential prognostic significance in predicting treatment outcome in leukaemias . These include immunophenotypic subgroups of acute lymphoblastic leukaemia (ALL) and immature acute myeloid leukaemia, expression of individual surface antigens or combined immunophenotypic features, and more recently, molecules mediating the multidrug resistance phenotype or being involved in the regulation of drug-induced apoptosis . Most previous studies investigating the prognostic significance of antigen expression in leukaemia have not used the information provided by multiparameter flow cytometry and have chosen rather arbitrary cut-off points for marker positivity . Moreover, given significant associations between immunophenotypic features and genetic abnormalities in leukaemic cells, immunophenotyping as an independent predictor of treatment outcome has been questioned . Thus, except for lineage assignment of leukaemic blasts and definition of maturational status in ALL, information provided by immunophenotyping is currently not applied to risk-classification systems or used for planning patient treatment in leukaemia . We review some of the recent findings regarding the prognostic impact of distinct immunophenotypic features in acute leukaemias and myelodysplastic syndrome. Best Pract Res Clin Haematol, 2003 Dec, 16(4), 583 - 97 Flow cytometry in lymphoma diagnosis and prognosis: useful? Stetler-Stevenson M. Flow cytometry has become an important tool in the diagnosis of mature lymphoid neoplasms and the determination of prognosis in selected cases . The advantages of flow cytometry are based largely on its ability to analyse, rapidly and simultaneously, multiple cell properties in a quantitative manner . Flow cytometric immunophenotyping is useful in diagnosing lymphoma under the WHO classification system, where lymphoid neoplasms are separated into distinct clinical entities based upon morphology, immunophenotype, genetic abnormalities and clinical features . Flow cytometry can quantify the expression of proteins associated with a good or poor prognosis, detect multidrug resistance, and measure cell proliferation, making it useful in measuring prognostic indicators in lymphoid neoplasia . The unique attributes of flow cytometry therefore make it a valuable technique in the diagnosis and classification of lymphomas as well as the assessment of prognostic markers in lymphoma patients. Liver Transpl, 2003 Nov, 9(11), 1199 - 210 Bile secretory function after warm hepatic ischemia-reperfusion injury in the rat; Accatino L et al.; Hepatic ischemia-reperfusion (I-R) injury frequently is associated with cholestasis . However, the underlying mechanisms are not fully understood . The aim of the study is to assess bile secretory function in vivo in rats subjected to warm lobar hepatic ischemia at different times during reperfusion . A model of lobar 70% warm hepatic ischemia for 30 minutes was used with studies conducted at 1 and 6 hours and 1, 3, and 7 days after reperfusion . Bile secretory function was assessed after selective cannulation of bile ducts of ischemic (ILs) and nonischemic lobes (NILs) . Serum activity of hepatic alanine and aspartate aminotransferase was slightly increased in rats subjected to I-R, whereas serum bile salt levels increased early during reperfusion, returning to control values after 7 days . ILs showed mild reversible leukocyte infiltration and no significant necrosis . Bile flow and bile salt excretion were significantly decreased in ILs during the first 24-hour reperfusion period compared with sham-operated rats and NILs . A marked reduction in glutathione (GSH) excretion occurred at 1 and 6 hours and 1 and 3 days, which returned to control values after 7 days . Total GSH and both reduced and oxidized GSH levels in liver homogenate and arterial blood GSH levels were unchanged at all times . Protein mass of multidrug resistance protein 2 and its function, assessed by the hepatic maximum secretory rate of ceftriaxone, did not show significant changes in ILs or NILs compared with sham-operated rats . Liver tissue gamma-glutamyl transpeptidase (GGT) and gamma-glutamylcysteine synthetase activities remained unchanged, whereas biliary GGT and cysteine secretory rates were significantly increased in ILs and NILs . Administration of acivicin, a GGT inhibitor, resulted in decreased secretion of this enzyme into bile and a parallel marked increase in biliary GSH secretion compared with untreated ischemic rats . In conclusion, warm hepatic I-R induces reversible cholestatic changes in ILs . GSH secretory rates from both ILs and NILs were markedly decreased during reperfusion . The reversibility of this effect after GGT inhibition, as well as increased release of active GGT into bile and cysteine biliary secretory rates, suggest increased GSH degradation in bile . These findings might be relevant for the I-R-induced clinical cholestasis, as well as cholangiocyte injury, seen after hepatic ischemia. Int J Clin Oncol, 2003 Oct, 8(5), 326 - 31 C(H)OP refractory chronic lymphocytic leukemia patients in whom salvage chemotherapy chosen by evaluating multiple chemotherapeutic drug-resistant factors was remarkably effective; Matsunaga T et al.; It is well known that the expression of anticancer drug-resistant factors is elevated in patients with primary refractory or relapsed chronic lymphocytic leukemia (CLL) who have been treated with chemotherapy . We report here two C(H)OP refractory patients with CLL in whom salvage chemotherapy chosen by evaluating anticancer drug-resistant factors (glutathione-S-transferase-Pi {GST-Pi}, glycoprotein {GP}-170, multidrug resistance-associated protein {MRP}, and lung resistance protein {LRP}) was remarkably effective . A 71-year-old male patient was refractory to induction therapy with cyclophosphamide, vincristine, and prednisone (COP), and his leukemic cells at diagnosis displayed overexpression of GST-Pi and GP-170 . A 74-year-old female patient's condition had been stable; she had received ten courses of COP over 9 years . However, because systemic lymphadenopathies recurred, she was treated with chemotherapy consisting of cyclophosphamide, adriamycin, vincristine, and prednisone (CHOP) or dexamethasone, etoposide, ifosphamide, and carboplatin (DeVIC) . However, she did not respond at all, and her leukemic cells at recurrence displayed overexpression of GST-Pi . Therefore, we chose for these patients a salvage therapy consisting of dexamethasone and high-dose cytosine arabinoside (Ara C), to which neither GST-Pi nor GP-170 show any drug resistance . In both patients, this salvage therapy proved effective. Invest New Drugs, 2003 Nov, 21(4), 413 - 20 Quinolizidinyl derivatives of iminodibenzyl and phenothiazine as multidrug resistance modulators in ovarian cancer cells; Barbieri F et al.; The development of multidrug-resistance (MDR) in neoplastic cells is often responsible for the therapy failure and poor outcome of a number of human cancers . MDR may be associated with the expression of the multidrug transporter glycoprotein p170, encoded by the MDR1 gene, which acts as an ATP-dependent efflux pump by reducing the intracellular accumulation of some cytotoxic agents . A variety of iminodibenzyl and phenothiazine derivatives, characterized by the presence of a bicyclic, strongly basic, and highly lipophilic quinolizidine nucleus, were synthesized to investigate their ability to modulate the MDR phenotype . A set of 10 of them (named 1-10), bearing quinolizidine moiety linked through different connecting chains, were tested as chemoresistance-reversing agents on doxorubicin-resistant ovarian cancer cells (A2780-DX3) . A 51-fold resistance to doxorubicin was reported in the A2780-DX3 compared to the parental sensitive A2780 WT with mean IC(50) values of 0.02 and 1.02 muM, respectively . Moreover, overexpression of the glycoprotein p170 in the resistant cell line was detected by Western blot analysis . By cytotoxicity assays and time-course experiments, different treatment schedules with resistance modulators (including clomipramine as reference drug) and doxorubicin were taken into account . The 16 h exposure of cells to 1 muM of modulator before doxorubicin demonstrated to be superior in sensitizing the resistant cell line . In particular, compounds 8, 7, 10, and 4 increasingly potentiated doxorubicin cytotoxicity, up to 5.6-fold in A2780-DX3 cells . The present results suggest promising indications for further development of these compounds as chemosensitizing drugs. J Med Chem, 2003 Nov 6, 46(23), 4988 - 5004 Three-dimensional quantitative structure-activity relationship analysis of propafenone-type multidrug resistance modulators: influence of variable selection on test set predictivity; Fleischer R et al.; An extended set of multidrug-resistance modulators of the propafenone type were investigated using CoMFA and CoMSIA . A number of 3D-QSAR models were derived from steric, electrostatic, and hydrophobic fields and their combinations . The hydrophobic fields alone and in combination with the steric and both (steric and electrostatic) fields yielded the models with the highest cross-validated predictivity, in agreement with a previous analysis of a smaller data set of propafenone-type multidrug-resistance (MDR) modulators . Inclusion of lipophilicity did not lead to an improvement of the models . The results point to the importance of hydrophobicity as a space-directed molecular property for MDR-modulating activity . The influence of variable selection applying the GOLPE procedure was investigated with an external test set . Variable-selection procedure was repetitively applied, keeping at each stage variables with uncertain contribution to the models . For the CoMFA-based 3D-QSAR models, an increase in external prediction quality was found . In contrast, the CoMSIA-based 3D-QSAR models were not improved by the GOLPE variable-selection procedure. Cancer, 2003 Nov 1, 98(9), 1958 - 66 Reduced folate carrier protein expression in osteosarcoma: implications for the prediction of tumor chemosensitivity; Ifergan I et al.; BACKGROUND: High-dose methotrexate (MTX) is an important component of current protocols for the treatment of osteosarcoma . Although MTX uptake proceeds primarily through the reduced folate carrier (RFC) protein and efflux occurs via multidrug resistance protein 1 (MRP1), RFC protein expression in osteosarcoma remains unexamined . METHODS: RFC and MRP1 expression (normalized to beta-actin expression) was examined with Western blot analysis in 11 osteosarcoma specimens obtained at diagnosis and 9 osteosarcoma specimens obtained on recurrence . RESULTS: The average RFC level in specimens obtained on recurrence was significantly higher than the level in specimens obtained at diagnosis (P = 0.0005) . Furthermore, in all three matched pairs of diagnosis and recurrence specimens, RFC levels were higher in recurrence specimens than in the corresponding diagnosis specimens . Potential correlations between RFC and MRP1 expression and histologic response to preoperative chemotherapy were examined . Tumors with poor histologic responses (i.e., </= 90% necrosis) had significantly lower RFC levels than did those with favorable responses to chemotherapy (P = 0.0016) . In contrast, there was no correlation between MRP1 levels at diagnosis and histologic response to chemotherapy (P = 0.8764) . The elevated MRP1 levels in specimens obtained on recurrence relative to MRP1 levels in specimens obtained at diagnosis were not statistically significant (P = 0.2056) . CONCLUSIONS: The significant correlation between low RFC levels at diagnosis and poor histologic response to preoperative chemotherapy suggests that RFC levels at diagnosis may be a useful predictor of chemosensitivity and warrants large-scale studies . In addition, postchemotherapy progression to recurrence is associated with a significant increase in RFC expression . To our knowledge, the current study is the first to examine RFC protein levels in tumor specimens . Cancer 2003 . Cell Motil Cytoskeleton, 2003 Dec, 56(4), 225 - 36 Vaults bind directly to microtubules via their caps and not their barrels; Eichenmuller B et al.; Vaults are large (13 Mda) ribonucleoprotein particles that are especially abundant in multidrug resistant cancer cells and have been implicated in nucleocytoplasmic drug transport . To understand how these large barrel-shaped complexes are transported through the cytosol, we examined the association of vaults with microtubules both in vitro and in vivo . Within cells, a subpopulation of vaults clearly associates with microtubules, and these vaults remain associated with tubulin dimers/oligomers when microtubules are disassembled by nocodazole treatment . In vitro, a microtubule-pull down assay using highly purified rat vaults and reassembled microtubules reveals that vaults exhibit concentration-dependent binding to microtubules that does not require the carboxyl terminal end of tubulin . Remarkably, negative staining for electron microscopy reveals that vault binding to microtubules is mediated by the vault caps; more than 82% of bound vaults attach to the microtubule lattice with their long axes perpendicular to the long axis of the microtubule . Five to six vault particles were bound per micron of microtubule, with no crosslinking of microtubules observed, suggesting that only one end of the vault can bind microtubules . Taken together, the data support the model of vaults as barrel-shaped containers that transiently interact with microtubules . Pharmacogenetics, 2003 Nov, 13(11), 675 - 82 ABCB1 C3435T and G2677T/A polymorphism decreased the risk for steroid-induced osteonecrosis of the femoral head after kidney transplantation; Asano T et al.; Advances in transplantation technology have brought about great benefits to patients suffering from organ failure, but the problem still remains of complications induced by steroids used for post-transplant immunosuppression . Among the side-effects caused by steroids, non-traumatic osteonecrosis of the femoral head (ONF) constitutes a serious problem . The same protocol for steroid administration induces ONF in some patients, but not in others, indicating the presence of individual difference in steroid sensitivity . We hypothesized that this difference might be mediated by the drug-transport protein, P-glycoprotein (P-gp), and investigated the relationship between single nucleotide polymorphisms in the multidrug resistance gene 1 (ABCB1, MDR1) encoding P-gp and ONF . Subjects comprised 136 patients receiving kidney transplantation . Thirty patients developed post-transplant ONF . Genomic DNA was extracted from peripheral blood, and genotypes of ABCB1 C3435T (exon 26) and G2677T/A (exon 21) were determined by direct sequencing . Multivariate analyses based on clinical information were performed to determine the relationship between ABCB1 genotypes and ONF . The dose/concentration (D/C) ratios of tacrolimus were also determined to estimate the activity of P-gp in patients with different genotypes of ABCB1 C3435T (CC, CT, TT), and in those who did and did not develop ONF . The ABCB1 3435TT genotype showed a significantly lower incidence of ONF (adjusted odds ratio = 0.10, P = 0.034) . The D/C ratio in the 3435TT genotype was significantly higher than that in the 3435CC genotype . The D/C ratio in patients developing ONF was significantly higher than in those patients who did not develop ONF . The results suggest increased activity of P-gp in patients with the 3435TT genotype and in those who did not develop ONF . The ABCB1 2677 homozygous variant type also showed a lower incidence of ONF (adjusted odds ratio = 0.26, P = 0.056) . The 3435T and 3435C alleles were in linkage disequilibrium with the 2677T and the 2677G alleles, respectively, in the study population . An assessment of C3435T and G2677T/A polymorphisms preceding steroid treatment could be useful for predicting the resistance to ONF development . Pharmacogenetics, 2003 Nov, 13(11), 661 - 74 Association between ABCB1 (multidrug resistance transporter) genotype and post-liver transplantation renal dysfunction in patients receiving calcineurin inhibitors; Hebert MF et al.; OBJECTIVE: Renal dysfunction is a common and costly adverse outcome of long-term treatment with calcineurin inhibitors (CNIs) . We conducted a retrospective, case-control study to test whether the risk of renal dysfunction in liver transplantation patients receiving CNIs is associated with the 2677G>T transversion in exon-21 of the gene (ABCB1) encoding P-glycoprotein . A total of 120 non-Hispanic white patients were evaluated . RESULTS: The overall incidence of renal dysfunction by year 3 post-transplantation was 40% . The frequency of renal dysfunction was reduced among patients with an ABCB1 2677TT genotype, as compared to those with a 2677GG genotype . Subjects with a heterozygote genotype behaved phenotypically like the 2677GG group . Comparing those subjects with a 2677TT genotype to the combined group of subjects with a 2677GG, TG, AT, or AG genotype resulted in an odds ratio of 0.26 (0.09-0.77) . When subjects were stratified by gender, the frequency of renal dysfunction was reduced among men with an ABCB1 2677TT genotype, relative to men with different genotypes . A similar odds ratio was obtained for women, but it did not achieve significance . When 18 subjects with an elevated SCr concentration just prior to surgery were excluded from the year 3 analysis, the association between the 2677TT genotype and chronic renal dysfunction in the remaining cohort was strengthened comparing genotype groups . CONCLUSIONS: Based on these results, we conclude that homozygosity for the ABCB1 2677T (S893) allele is associated with reduced risk of chronic renal dysfunction among liver transplantation patients receiving an immunosuppressive regimen containing CNIs . Pharmacogenetics, 2003 Nov, 13(11), 651 - 60 Effects of ABCB1 (multidrug resistance transporter) gene mutations on disposition and central nervous effects of loperamide in healthy volunteers; Skarke C et al.; OBJECTIVE: Mutations in the ABCB1 gene have been associated with decreased expression and net function of P-glycoprotein (P-gp) . We investigated the modulation of the central nervous effects of loperamide resulting from ABCB1 genetic variants . METHODS: On two occasions, 20 healthy volunteers received 24 mg loperamide suspension orally and, in a double-blind randomized two-way crossover fashion, 800 mg quinidine or placebo orally 1 h before loperamide . Pupil size was measured for 5 h following loperamide administration, and plasma concentrations of loperamide and quinidine were measured for 6 h . Single nucleotide polymorphisms and haplotypes including G2677T(A) (exon 21) and C3435T (exon 26) were analysed for their relation to plasma concentrations of quinidine and loperamide and to the miotic effects of loperamide . RESULTS: Loperamide plasma concentrations with quinidine co-administration were about twice as high as those without quinidine . The ABCB1 haplotype G2677/T3435 was associated with the highest loperamide plasma concentrations, which were about 1.5 times higher than in non-carriers of this haplotype . Plasma concentrations of quinidine did not differ among carriers and non-carriers of genetic variants . When quinidine was co-administered with loperamide, pupil size decreased . Without quinidine it changed only minimally . The ABCB1 TT3435 genotype was associated with the most pronounced increase of the miotic effects of loperamide when quinidine was co-administered . This was accompanied by a tendency toward higher plasma loperamide in TT3435 carriers . CONCLUSIONS: Our data support a functional importance of the ABCB1 mutations for plasma concentrations and central nervous actions of the opioid loperamide . Cancer Res, 2003 Oct 15, 63(20), 6942 - 7 HMN-176, an active metabolite of the synthetic antitumor agent HMN-214, restores chemosensitivity to multidrug-resistant cells by targeting the transcription factor NF-Y; Tanaka H et al.; HMN-176 ((E)-4-{{2-N-{4-methoxybenzenesulfonyl}amino}stilbazole}1-oxide) is an active metabolite of HMN-214 ((E)-4-{2-{2-(N-acetyl-N-{4-methoxybenzenesulfonyl}amino)stilbazole}}1-oxide), which has a potent antitumor activity in mouse xenograft models . In this study, we show that HMN-176 circumvents multidrug resistance in a K2 human ovarian cancer subline selected for Adriamycin resistance (K2/ARS) . Upon treatment of K2/ARS cells with 3 microM HMN-176, the GI(50) of Adriamycin for the cells decreased by approximately 50% . To explore the molecular mechanism of this effect, we assessed the expression of the multidrug resistance gene (MDR1), which is constitutive in K2/ARS cells, at both the protein and the mRNA level . Western and reverse transcription-PCR analysis revealed that the expression of MDR1 was significantly suppressed by treatment with HMN-176 . Furthermore, when administered p.o., HMN-214 suppressed the expression of MDR1 mRNA in a mouse xenograft model implanted with KB-A.1, an Adriamycin-resistant cell line . Luciferase reporter fusion gene analysis demonstrated that HMN-176 inhibited the Y-box-dependent promoter activity of the MDR1 gene in a dose-dependent manner . Moreover, we show by electrophoretic mobility shift assay that HMN-176 inhibits the binding of NF-Y, which is thought to be an essential factor for the basal expression of MDR1, to its target Y-box consensus sequence in the MDR-1 promoter . Inhibition of MDR-1 expression was achieved with pharmacological concentrations of HMN-176, suggesting that HMN-176 may act by two different mechanisms-cytotoxicity and MDR1 down-regulation-simultaneously . The data presented strongly suggest that the antitumor mechanism of HMN-176 (or its prodrug HMN-214 in vivo) is quite different from those of known antitumor agents. Eur Respir J, 2003 Oct, 22(4), 637 - 42 Risk factors for recent transmission of Mycobacterium tuberculosis; Heldal E et al.; In recent decades, the decline of tuberculosis has stopped in Western Europe, mainly due to increased immigration from high-prevalence countries . The objective of the current study was to identify risk factors for developing tuberculosis following recent infection, in order to better target interventions . Strains from 861 culture-positive cases, diagnosed in Norway in 1994-1999, were analysed by use of restriction fragment length polymorphism (RFLP) . A cluster was defined as two or more isolates with identical RFLP patterns . Risk factors for being part of a cluster were identified by univariate and multivariate analysis . A total of 134 patients were part of a cluster . These constituted 5% Asian-born, 18% Norwegian-born, 24% European-born and 29% African-born patients . Four independent risk factors for being part of a cluster were identified: being born in Norway, being of young age, being infected with an isoniazid-resistant strain and being infected with a multidrug-resistant strain . Transmission of tuberculosis may be further reduced by improving case management, contact tracing, preventive treatment, screening of immigrants and access to health services for the foreign-born population. Clin Cancer Res, 2003 Oct 15, 9(13), 5009 - 17 Multidrug-resistant tumor cells remain sensitive to a recombinant interleukin-4-Pseudomonas exotoxin, except when overexpressing the multidrug resistance protein MRP1; de Jong MC et al.; Tumor cells may become resistant to conventional anticancer drugs through the occurrence of transmembrane transporter proteins such as P-glycoprotein (ABCB1), breast cancer resistance protein (ABCG2), or members of the multidrug resistance-associated protein family (MRP1-MRP5; ABCC1-ABCC5) . In this report, we studied whether tumor cells that are cytostatic drug resistant because of overexpression of one of the above mentioned proteins are sensitive to a new anticancer agent, interleukin-4 toxin (IL-4 toxin) . IL-4 toxin is a fusion protein composed of circularly permuted IL-4 and a truncated form of Pseudomonas exotoxin (PE) {IL-4(38-37)-PE38KDEL} . Ninety-six-h cytotoxicity assays and 10-day clonogenic assays showed that drug-selected multidrug resistant (MDR) tumor cells that overexpress P-glycoprotein or breast cancer resistance proteins are still sensitive to IL-4 toxin . Also, tumor cells transfected with cDNA for MRP2-5 showed no resistance, or marginal resistance, only to the toxin as compared with the parent cells . In contrast, MRP1-overexpressing cells, both drug selected and MRP1 transfected, are clearly resistant to IL-4 toxin with resistance factors of 4.3 to 8.4 . MRP1-overexpressing cells were not resistant to PE itself . IL-4 toxin resistance in MRP1-overexpressing cells could be reversed by the MRP1 inhibitors probenecid or MK571 and were not affected by glutathione depletion by DL-buthionine-S,R-sulfoximine . In a transport assay using plasma membrane vesicles prepared from MRP1-overexpressing cells, IL-4 toxin and IL-4, but not PE, inhibited the translocation of the known MRP1 substrate 17beta-estradiol 17-(beta-D-glucuronide) (E(2)17betaG) . These data suggest that MRP1-overexpressing cells are resistant to IL-4 toxin because of extrusion of this agent by MRP1 . Still, the results of this study demonstrate that IL-4 toxin effectively kills most MDR tumor cells and, therefore, represents a promising anticancer drug. Placenta, 2003 Nov, 24(10), 951 - 8 Basal membrane localization of MRP1 in human placental trophoblast; Nagashige M et al.; The placental trophoblast is considered to act as a barrier between mother and fetus, mediating the exchange of various materials across the placenta . ATP-binding cassette (ABC) transporters such as P-glycoprotein (P-gp) and multidrug-resistance protein (MRP) are expressed in the placenta and function as efflux transport systems for xenobiotics . In the present study, we aimed to determine the localization of MRP1 in the human placenta in comparison with that of P-gp . Western blotting analysis with human placental membrane vesicles indicated that P-gp and MRP1 are localized on the brush-border membranes and basal membranes, respectively . Immunohistochemical analysis with human normal full-term placenta showed that anti-P-gp monoclonal antibody F4 stained the brush-border side of the trophoblast cells, whereas anti-MRP1 monoclonal antibody MRPr1 stained the basal side . These results confirm that P-gp and MRP1 are located on the brush-border membranes and basal membranes, respectively, of human full-term placental trophoblast . MRP1 was also detected on the abluminal side of blood vessels in the villi . Accordingly, MRP1 may play a role distinct from that of P-gp, which is considered to restrict the influx of xenobiotics into the fetus. Clin Chem Lab Med, 2003 Oct, 41(10), 1345 - 50 CYP3A4 and MDR1 alleles in a Portuguese population; Cavaco I et al.; Polymorphisms in cytochrome P450 CYP3A4 and multidrug resistance (MDR) 1 genes coding for the important drug-metabolising CYP3A4 and the ATP-binding cassette (ABC) transporter P-glycoprotein (Pgp) are poorly documented in the Portuguese population . In this study we have determined the frequencies of CYP3A4 and MDR1 alleles in Portuguese Caucasians . Both genes were simultaneously analysed as these genes are known to be frequently co-induced and their products to show a pronounced overlap of substrates . CYP3A4 A-392G (CYP3A4*1B), T673C (CYP3A4*2) and MDR1 T-129C, G2677T and C3435T single nucleotide polymorphisms (SNPs) were analysed in 100 individuals from the southern region of the country . We observed a frequency of 4.0% for CYP3A4*1B, not significantly different from that reported on other Caucasian European populations . CYP3A4*2 was found at an allele frequency of 4.5%, constituting the first report of the presence of this allele outside the Finnish population . Significant differences were found concerning the MDR1 C3435T SNP frequency (64.5%) compared with other European populations, while no differences were found concerning G2677T (47.5%) or T-129C (5%) SNPs . Linkage between the C3435T and G2677T SNPs was observed, although not as evidently as documented in other Caucasian populations . No preferential associations were detected between CYP3A4 and MDR1 alleles. Am J Pathol, 2003 Nov, 163(5), 1781 - 90 Human SPF45, a splicing factor, has limited expression in normal tissues, is overexpressed in many tumors, and can confer a multidrug-resistant phenotype to cells; Sampath J et al.; Our effort to identify novel drug-resistant genes in cyclophosphamide-resistant EMT6 mouse mammary tumors led us to the identification of SPF45 . Simultaneously, other groups identified SPF45 as a component of the spliceosome that is involved in alternative splicing . We isolated the human homologue and examined the normal human tissue expression, tumor expression, and the phenotype caused by overexpression of human SPF45 . Our analyses revealed that SPF45 is expressed in many, but not all, normal tissues tested with predominant expression in normal ductal epithelial cells of the breast, liver, pancreas, and prostate . Our analyses using tissue microarrays and sausages of tumors indicated that SPF45 is highly expressed in numerous carcinomas including bladder, breast, colon, lung, ovarian, pancreatic, and prostate . Interestingly, this study revealed that overexpression of SPF45 in HeLa, a cervical carcinoma cell line, resulted in drug resistance to doxorubicin and vincristine, two chemotherapeutic drugs commonly used in cancer . To our knowledge, this is the first study showing tumor overexpression of an alternate splicing factor resulting in drug resistance. Mol Cell Biochem, 2003 Oct, 252(1-2), 109 - 16 Resistance to thapsigargin-induced intracellular calcium mobilization in a multidrug resistant tumour cell line; Wagner-Souza K et al.; A multidrug resistant (MDR) cell line, derived from the human leukaemic cell K562 and selected for its resistance to Vincristine, was shown to be resistant to Thapsigargin (TG) . A concentration of 50 nM TG was toxic to K562 cells whereas the MDR cell line, known as Lucena I cells, survived unaffected for up to seven days in culture . Similarly, no intracellular Ca2+ mobilization was observed in the MDR cell line treated with TG . This effect was not a result of TG extrusion by P glycoprotein (Pgp), as no mobilization was observed even in the presence of the Pgp inhibitors Verapamil (5 microM) and Cyclosporin A (0.16 microM) . In the present study, both cell lines expressed comparable levels of Bcl-2 making it unlikely that Bcl-2 was involved in this process . Similarly, no overexpression of the endoplasmic reticulum Ca2+ ATPase (SERCA) could be detected in the MDR cell line and Ca2+ uptake by vesicles of the two cell types were equally sensitive to TG . These results confirm that MDR cells do not mobilize Ca2+ in the presence of TG but go against the possibility that this might be due to TG extrusion or to the overexpression of a resistant SERCA isoform. Oncogene, 2003 Oct 20, 22(47), 7496 - 511 Transcriptional regulation of ABC drug transporters; Scotto KW; P-glycoprotein, the founding member of the ATP-binding cassette (ABC) family of drug transporters, was first identified almost three decades ago and shown to confer resistance to multiple chemotherapeutic agents when overexpressed in human tumors . Subsequent years have witnessed a tremendous effort to characterize the function and regulation of P-glycoprotein, initially spurred by the hope that its inhibition was the key to overcoming clinical resistance to multiple anticancer agents . However, the identification of MRP1, another member of the ABC drug transporter family, led to the realization that the multidrug resistance (MDR) phenotype is considerably more complex than initially believed . Indeed, at the present time at least 10 members of the ABC transporter family have been implicated in an MDR phenotype, and it is likely that more will be added to this list as studies progress . With this complexity comes the imperative to improve our understanding of the function of individual transporters, as well as to delineate the mechanisms underlying their expression in normal and tumor cells, particularly those that may be amenable to therapeutic intervention . Several articles within this volume address the structure and function of drug transporters . This review will focus on our current understanding of the regulation of ABC drug transporters at the level of transcription. Oncogene, 2003 Oct 20, 22(47), 7340 - 58 Multidrug resistance mediated by the breast cancer resistance protein BCRP (ABCG2); Doyle LA et al.; Observations of functional adenosine triphosphate (ATP)-dependent drug efflux in certain multidrug-resistant cancer cell lines without overexpression of P-glycoprotein or multidrug resistance protein (MRP) family members suggested the existence of another ATP-binding cassette (ABC) transporter capable of causing cancer drug resistance . In one such cell line (MCF-7/AdrVp), the overexpression of a novel member of the G subfamily of ABC transporters was found . The new transporter was termed the breast cancer resistance protein (BCRP), because of its identification in MCF-7 human breast carcinoma cells . BCRP is a 655 amino-acid polypeptide, formally designated as ABCG2 . Like all members of the ABC G (white) subfamily, BCRP is a half transporter . Transfection and enforced overexpression of BCRP in drug-sensitive MCF-7 or MDA-MB-231 cells recapitulates the drug-resistance phenotype of MCF-7/AdrVp cells, consistent with current evidence suggesting that functional BCRP is a homodimer . BCRP maps to chromosome 4q22, downstream from a TATA-less promoter . The spectrum of anticancer drugs effluxed by BCRP includes mitoxantrone, camptothecin-derived and indolocarbazole topoisomerase I inhibitors, methotrexate, flavopiridol, and quinazoline ErbB1 inhibitors . Transport of anthracyclines is variable and appears to depend on the presence of a BCRP mutation at codon 482 . Potent and specific inhibitors of BCRP are now being developed, opening the door to clinical applications of BCRP inhibition . Owing to tissue localization in the placenta, bile canaliculi, colon, small bowel, and brain microvessel endothelium, BCRP may play a role in protecting the organism from potentially harmful xenobiotics . BCRP expression has also been demonstrated in pluripotential "side population" stem cells, responsible for the characteristic ability of these cells to exclude Hoechst 33342 dye, and possibly for the maintenance of the stem cell phenotype . Studies are emerging on the role of BCRP expression in drug resistance in clinical cancers . More prospective studies are needed, preferably combining BCRP protein or mRNA quantification with functional assays, in order to determine the contribution of BCRP to drug resistance in human cancers. Antimicrob Agents Chemother, 2003 Nov, 47(11), 3616 - 9 Resazurin microtiter assay plate testing of Mycobacterium tuberculosis susceptibilities to second-line drugs: rapid, simple, and inexpensive method; Martin A et al.; The emergence of multidrug-resistant tuberculosis calls for new, rapid drug susceptibility tests . We have tested 150 Mycobacterium tuberculosis isolates against the second-line drugs ethionamide, kanamycin, capreomycin, ofloxacin, and para-aminosalicylic acid by the colorimetric resazurin microtiter assay and the proportion method . By visual reading, MICs were obtained after 8 days . A very good correlation between results by the colorimetric resazurin microtiter assay and the proportion method was obtained . The colorimetric resazurin microtiter assay is inexpensive, rapid, and simple to perform, and implementation of the assay is feasible for low-resource countries. Zhonghua Zhong Liu Za Zhi, 2003 Sep, 25(5), 425 - 8 {Mdr-1 ribozyme in the reversal of multidrug resistance in human ovarian cancer}; Yang XK et al.; OBJECTIVE: To study the mechanism of multidrug resistance and its reversal by mdr-1 ribozyme in human ovarian cancer . METHODS: The expression of mdr-1 and p-glycoprotein (p-gp) was studied by confocal laser microscope (Confocal), RT-PCR and Western blot analysis in adriamycin-resistant human ovarian cancer cell line (A2780/ADM) and adriamycin-sensitive one (A2780) . The mdr-1 ribozyme was transfected into the A2780/ADM by Lipofectamine 2000 to overcome the multidrug resistance in ovarian cancer . RESULTS: The expression of mdr-1 mRNA and p-gp in A2780/ADM was significantly higher than that in A2780 . The expression of mdr-1 mRNA and p-gp in A2780/ADM was lowered after being transfected by mdr-1 ribozyme . CONCLUSION: Multidrug resistance of A2780/ADM, possibly being caused by overexpression of mdr-1 gene, can be partially reversed by mdr-1 ribozyme. Zhongguo Shi Yan Xue Ye Xue Za Zhi, 2003 Oct, 11(5), 544 - 8 {Multidrug resistance mediated by membrane P-glycoprotein in acute myeloid leukemia}; Su LP; A key issue in the treatment of acute leukemia is the development of resistance to chemotherapeutic drugs . Several mechanisms may account for this phenomenon, including failure of the cell to undergo apoptosis in response to chemotherapy, or failure of the drug to reach and/or affect its intracellular target . This review focuses on the latter mechanisms, and on intracellular drug transport resistance mechanisms in particular . Expression of the ATP-binding cassette (ABC) transporter P-glycoprotein (P-gp) has generally been reported to correlate with prognosis in acute myeloid leukemia (AML) . Additionally, of more controversial, expression of the ABC transporter multidrug resistance protein (MRP) and the vault-transporter lung resistance protein (LRP) have been correlated with the outcome in AML. Zhongguo Shi Yan Xue Ye Xue Za Zhi, 2003 Oct, 11(5), 472 - 5 {Expression of lung resistance protein and multidrug resistance protein genes in bone marrow cells of acute leukemia patients and its clinical significance}; Chi ZH et al.; To study the expression of lung resistance protein (LRP) and multidrug resistance protein (MRP) genes in bone marrow cells in patients with acute leukemia and its clinical significance, expression of LRP and MRP mRNA in bone marrow cells from 47 cases of acute leukemia, including 10 refractory or relapsed cases, and 7 normal individuals were determined by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) . The result s showed that expression of LRP gene was negative in normal individuals . LRP mRNA level in newly treated cases of acute myelocytic leukemia and refractory or relapsed cases was significantly higher than that in normal individuals, increased LRP mRNA level has correlation with lower sensitivity to initial chemotherapy and was associated with reduced overall survival rate . Complete remission (CR) rate in LRP positive patients was lower than that in negative cases . The level of LRP expression was correlated with that of MRP mRNA . In conclusion, the expression of LRP mRNA can predict the treatment outcome and prognosis for acute myelocytic leukemia, prognosis was even worse in LRP and MRP linked expression cases, therefore, LRP was an important resistant factor, determination of LRP and MRP expression can help us to evaluate the prognosis and choose chemotherapy program. Leukemia, 2004 Jan, 18(1), 78 - 83 Multidrug resistance genes in infant acute lymphoblastic leukemia: Ara-C is not a substrate for the breast cancer resistance protein; Stam RW et al.; Infants with acute lymphoblastic leukemia (ALL) are more resistant to chemotherapeutic drugs than older children with ALL, except for Ara-C . Drug resistance mechanisms in infant ALL, however, remain unknown . Possibly, multidrug resistance (MDR) proteins like P-glycoprotein, MDR-associated protein (MRP1), lung resistance-related protein (LRP/MVP) and the breast cancer resistance protein (BCRP) play a role . Accordingly, we measured the mRNA levels of these proteins in infants (n=13) and non-infants (n=13) with ALL, using quantitative RT-PCR . Infants expressed 2.4-fold less BCRP mRNA (P=0.009) than non-infants with ALL . MDR1, MRP1 and LRP/MVP expression did not differ between both groups . MDR gene expression levels did not correlate to prednisolone, vincristine, daunorubicin or Ara-C cytotoxicity, except for BCRP expression, which correlated with resistance to Ara-C (Rs=0.53, P=0.012), suggesting that Ara-C might be a BCRP substrate . However, culturing patients ALL cells in the presence of the BCRP inhibitor Ko143 had no effect on Ara-C sensitivity . Inhibiting Bcrp1 in the Mdr1a-, Mdr1b- and Mrp1-deficient and Bcrp1-overexpressing mouse cell line Mef3.8/T6400, also did not modulate Ara-C cytotoxicity . Therefore, we conclude that Ara-C is not a substrate for BCRP and that MDR proteins do not play a significant role in drug resistance in infant ALL. Sex Transm Infect, 2003 Oct, 79(5), 419 - 21 Selective transmission of multidrug resistant HIV to a newborn related to poor maternal adherence; Desai N et al.; OBJECTIVES: To report perinatal transmission of multidrug resistant (MDR) HIV related to variable maternal adherence antenatally . METHODS: Case study including review of clinic records, adherence information, laboratory data, and HIV genotyping results in mother and infant . RESULTS: Poor maternal adherence to clinic visits and antiretroviral therapy contributed to detectable viraemia antenatally . When tested for the first time at age 6 months, the infant was found to have virus with resistance to multiple drugs . In this case, prophylaxis with zidovudine (AZT) failed to prevent the transmission of the MDR strain . CONCLUSIONS: Perinatal transmission of MDR HIV can occur despite standard peripartum prophylaxis with AZT . Perinatal prophylaxis should be tailored to the mother's treatment history and resistance profile . Paediatric HIV specialists should be prepared to deal with a small, but slowly increasing number of babies with a "nightmare" multidrug resistant virus with limited treatment options. Mol Pharmacol, 2003 Nov, 64(5), 1259 - 69 Cloning and Characterization of the Murine and Rat mrp1 Promoter Regions; Muredda M et al.; The ATP-binding cassette transporter multidrug resistance protein 1 (MRP1) confers resistance to a number of clinically important chemotherapeutic agents . The proximal promoter region of MRP1 is GC-rich and contains binding sites for members of the Sp1 family of trans-acting factors that seem to be important for basal expression . As an approach to searching for other elements that may contribute to expression, we have sequenced and functionally compared the promoters of the murine and rat mrp1 genes with that of the human gene . All three promoters are GC-rich, TATA-less, and CAAT-less . Conservation of sequence between rodent and human promoters is limited to a proximal region of 100 nucleotides containing binding sites for members of the Sp1 family and a putative activator protein-1 element . The 5'-untranslated region (UTR) of human MRP1 contains an insertion of approximately 160 nucleotides comprising a GCC-triplet repeat and a GC-rich tandem repeat that is absent from the rodent sequences . Transient transfection analyses demonstrated that the conserved GC-boxes of all three genes are the major determinants of basal activity . Based on electrophoretic mobility shift assays, each GC-box can be bound by Sp1 or Sp3 . Unlike the rodent genes, the human MRP1 5'UTR also binds Sp1 but not Sp3, and the human promoter retains substantial activity even in the absence of the conserved GC-boxes . Finally, we show that the tumor suppressor protein p53 can repress the human and rodent promoters by a mechanism that is independent of the Sp1 elements. Farmaco, 2003 Nov, 58(11), 1163 - 9 A novel sunscreen agent having antimelanoma activity; Nogueira MA et al.; A novel series of eight dibenzoylmethane derivatives having both sunscreen and cytotoxic activity has been obtained by derivatizing commercial dibenzoyl methanes . Four human cancer cell lines (MCF 7 (breast), NCI ADR (breast expressing the multidrug resistance phenotype), NCI 460 (lung) and UACC 62 (melanoma)) were used for the cytotoxic assay . Eight among the 19 dibenzoylmethane derivatives showed cytotoxicity against these four cell lines . Absorption spectroscopies revealed that these compounds can be used as sunscreens against UV radiation. Zhonghua Gan Zang Bing Za Zhi, 2003 Oct, 11(10), 609 - 11 {Expression and implication of multidrug resistance associated -protein gene in primary hepatocellular carcinoma}; Wang BL et al.; OBJECTIVES: To investigate the relationship between the expression of mrp and both the responses to chemotherapy and the level of alpha-fetoprotein (AFP) . METHODS: S-P immunohistochemical staining and in situ PCR were adopted to detect MRP and mRNA mrp in 54 cancer tissues taken from untreated HCC patients whose tumor could not be removed during the operation, 24 para-cancer tissues, and 12 posthepatitis cirrhosis paraffin-embedded tissues . The relationship between the expression of mrp and their curative effect to chemotherapy in all the patients was analyzed, so was the relationship between the expression of mrp and the level of AFP in 38 patients whose AFP was positive after operation . RESULTS: The positive rates of expressing MRP and mRNA mrp in the three kinds of tissues were 61.1%, 25.0%, 33.3% and 77.8%, 37.5%, 41.7%, respectively, with higher rates in HCC tissues than those in other tissues (chi2=9.842, P< 0.01; chi2=13.956, P<0.01) . The rates of curative effect to chemotherapy in groups of negative and positive MRP and mRNA mrp expression were 61.9%, 30.3% and 75.0%, 33.3%, respectively, with significant difference between the negative and positive groups (chi2=5.242, P<0.05; chi2=6.627, P< 0.05) . As the same as the percentage of curative effect to chemotherapy, the rates of AFP level decreased evidently were 62.5%, 27.3% and 87.5%, 30.0%, with remarkable difference between the two groups (chi2=4.710, P<0.05; chi2=8.566, P<0.05) . CONCLUSIONS: The multidrug resistance (MDR) of HCC is related to mrp expression, which initiates the intrinsic MDR . There is an important significance by detecting mrp expression in selecting chemotherapeutic method, and the expression of mrp can act as an indicator for chemotherapeutic sensitivity in HCC patients. Breast Cancer Res Treat, 2003 Sep, 81(2), 149 - 57 Expression of MRP1, LRP and Pgp in breast carcinoma patients treated with preoperative chemotherapy; Rudas M et al.; Our purpose was to determine the expression of the drug resistance factors multidrug resistance protein (MRP1), lung resistance protein (LRP) and P-glycoprotein (Pgp) in breast carcinoma patients treated with preoperative chemotherapy . We have studied the expression of these proteins in breast carcinomas by immunohistochemistry both prior (n = 80) and after (n = 68) preoperative chemotherapy and compared their expression with response to preoperative chemotherapy . In paired samples prior and after chemotherapy expression of drug resistance factors was significantly lower in prechemotherapy samples as compared with postchemotherapy specimens . This was observed for MRP1 (62% vs . 88%, P < 0.001), LRP (65% vs . 97%, P < 0.001) and Pgp (55% vs . 100%, P < 0.001) . Prechemotherapy expression of MRP1 was more frequently observed in patients with distant metastases than in those without (50% vs . 8%, P = 0.02) . No associations were observed between LRP expression and clinical parameters . Pgp expression was more frequently detected in lobular carcinomas than in ductal carcinomas (93% vs . 46%, P = 0.001) and in patients with positive lymph nodes than in patients with negative lymph nodes (65% vs . 31%, P = 0.008) but was independent of other clinical parameters . No significant associations were found between the prechemotherapy or postchemotherapy expression of either of these three proteins and response to preoperative chemotherapy . However, prechemotherapy MRP1 expression was significantly associated with shorter progression-free survival of the patients (P = 0.02), whereas no such associations were observed for either LRP or Pgp . In conclusion, preoperative chemotherapy increases the expression of MRP1, LRP and Pgp . Response to chemotherapy is not associated with pre- or postchemotherapy expression levels of these drug resistance proteins but time to progression may be influenced by prechemotherapy MRP1 expression. Drug Metab Dispos, 2003 Nov, 31(11), 1337 - 45 Constitutive expression of various xenobiotic and endobiotic transporter mRNAs in the choroid plexus of rats; Choudhuri S et al.; The aim of this study was to quantitatively determine the constitutive expression levels of various transporter mRNAs in rat choroid plexus . To provide a reference for the relative expression levels, the expression of various transporter mRNAs in choroid plexus were compared with that in liver, kidney, and ileum . The mRNA levels of multidrug resistance protein (Mrp)1, 2, 3, 4, 5, and 6; multidrug resistance (Mdr)1a, 1b, and 2; organic anion transporting polypeptide (Oatp)1, 2, 3, 4, 5, 9, 12, and Oat-K (1/2); organic anion transporter (Oat)1, 2, and 3; organic cation transporter (Oct)1, 2, 3, N1, and N2; bile acid transporters sodium taurocholate cotransporting polypeptide (Ntcp), bile salt excretory protein (Bsep), and ileal bile acid transporter (Ibat); divalent metal transporter 1 (DMT1), Menke's and Wilson's metal transporters; equilibrative nucleotide transporters (Ent) 1 and 2, and constitutive nucleotide transporters (Cnt)1 and 2; peptide transporters (Pept)1 and 2; as well as ATP-binding cassette (Abc)G5 and 8 were measured in choroid plexus by the branched DNA signal amplification method . Mrp1, 4, and 5, Oatp3, Menke's transporter, DMT1, Ent1, and Pept2 mRNAs were expressed in choroid plexus at higher levels than in liver, kidney, or ileum . OctN1 and N2, Oatp2, Oat2 and 3, and Cnt1 and 2 mRNAs expressions were detectable in choroid plexus, but the levels were lower compared with that in liver, kidney, or ileum . The remaining transporters {Mrp2, Mrp3, Oct1, Oct2, Oatp1, Oatp4, Oatp5, Oatp12, Oat-K (1/2), Ntcp, Bsep, Ibat, Mdr1a, Mdr1b, Mdr2, Oat1, Ent2, Pept1, AbcG5, AbcG8} were expressed at very low levels in choroid plexus . The constitutive expression levels of different transporters in choroid plexus may provide an insight into the range of xenobiotics that can potentially be transported by the choroid plexus, thereby providing a means of xenobiotic detoxification in the brain. Drug Metab Dispos, 2003 Nov, 31(11), 1315 - 9 Induction of multidrug resistance protein 3 (mrp3) in vivo is independent of constitutive androstane receptor; Cherrington NJ et al.; We previously demonstrated that multidrug resistance protein 3 (Mrp3/ABCC3) is induced in rat liver by phenobarbital (PB) and several other microsomal enzyme inducers that induce cytochrome P450 2B (CYP2B) . CYP2B is induced by constitutive androstane receptor (CAR)-retinoid X receptor (RXR) heterodimer binding to a phenobarbital-responsive promoter element in the CYP2B promoter . Hepatic mRNA levels of CYP2B and Mrp3 were measured in three models of altered CAR activity to determine whether CAR is also involved in the induction of Mrp3 . In Wistar Kyoto rats, where males express higher CAR protein levels than females, the induction of CYP2B1/2 was significantly higher in males than in females by PB, diallyl sulfide, and trans-stilbene oxide but not oltipraz . Mrp3 was induced by each of these treatments, but in contrast to CYP2B1/2, to a similar magnitude in males and females . In male hepatocyte-specific RXRalpha-/- mice, CYP2B10 was not induced by diallyl sulfide or oltipraz but remained inducible by PB and trans-stilbene oxide after considering the decrease in basal CYP2B10 expression . Mrp3, however, was induced by PB, diallyl sulfide, trans-stilbene oxide and oltipraz in both wild-type and RXRalpha-/- mice . Additionally, constitutive expression of Mrp3 was significantly reduced in RXRalpha-/- mice . In CAR-/- mice, the robust induction of CYP2B10 by PB was completely absent . However, Mrp3 was equally induced both in wild-type and CAR-/- mice by PB . These data clearly demonstrate that induction of hepatic Mrp3 by PB and other microsomal enzyme inducers is CAR-independent and implies a role for RXRalpha in the constitutive expression of Mrp3. Drug Metab Dispos, 2003 Nov, 31(11), 1296 - 9 Induction of ABCC3 (MRP3) by pregnane X receptor activators; Teng S et al.; The pregnane X receptor (PXR) mediates the induction of various genes by xenobiotics, including several ATP-binding cassette transporters . PXR is also activated by bile acids likely to prevent their accumulation to toxic levels; however, the role of PXR in the regulation of MRP3, an important bile acid efflux transporter, has not been elucidated . The impact of PXR activators on the hepatic expression of MRP3 was examined in vivo and in vitro . The human hepatoma cell lines HuH7 and HepG2 were treated with PXR activators including clotrimazole, rifampicin, 17beta-hydroxy-11beta-{4-dimethylamino phenyl}-17alpha-{1-propynyl}estra-4,9-dien-3-one (RU486), metyrapone, nifedipine, lithocholic acid, and 5-pregnen-3beta-ol-20-one-16alpha-carbonitrile (PCN) . Levels of MRP3 mRNA, as determined by reverse transcription-polymerase chain reaction, were induced 1.6- to 8-fold in a dose-dependent manner (p < 0.05) . Corresponding decreases in the multidrug resistance-associated protein-dependent cellular retention of 5-carboxyfluorescein were also seen in the treated HuH7 cells . In vivo studies demonstrated increased PXR mRNA and induction of MRP3 mRNA in the livers of wild-type mice treated with the PXR activator RU486 . On the other hand, MRP3 induction was not seen in the RU486-treated PXR-null mice . These results suggest that PXR activation may play a role in the regulation of MRP3 expression. Drug Metab Dispos, 2003 Nov, 31(11), 1288 - 91 The beta-D-glucoside and sodium-dependent glucose transporter 1 (SGLT1)-inhibitor phloridzin is transported by both SGLT1 and multidrug resistance-associated proteins 1/2; Walle T et al.; Phloridzin, a glucoside of the flavonoid-like polyphenol phloretin, has long been known to be a specific nontransportable inhibitor of the sodium-dependent glucose transporter SGLT1 . The objective of this study was to determine whether efflux by multidrug resistance-associated protein (MRP) transporters might have masked the absorption by SGLT1 in previous studies . Various cells used as transport models were incubated with phloridzin (50 microM) in the absence and presence of 50 microM 3-{{3-{2-(7-chloroquinolin-2-yl)vinyl}phenyl}-(2-dimethylcarbamoylethylsulfanyl)methylsulfanyl} propionic acid (MK-571), a highly selective MRP1/MRP2 inhibitor, and the cellular uptake of phloridzin was measured by high performance liquid chromatography . The uptake of phloridzin by SGLT1-transfected Chinese hamster ovary (CHO) (G6D3) cells was 1.7-fold higher than that by parent CHO cells (p < 0.01) . In the presence of MK-571, the uptake of phloridzin by CHO cells increased 3.7-fold (p < 0.001) . MK-571 caused an 8.0-fold increase in the uptake of phloridzin by G6D3 cells (p < 0.0001) . Thus, in the absence of MRP1 efflux, transport of phloridzin by SGLT1 was clearly demonstrated . Similar results were obtained for the glycosides of the flavonoids quercetin, genistein, and diosmetin . A significantly lower accumulation of phloridzin in MRP2-transfected Madin-Darby canine kidney (MDCK) cells compared with parent MDCK cells demonstrated that phloridzin was a substrate also for MRP2 (p < 0.05) . This conclusion was further strengthened when MK-571 increased the uptake by MRP2-MDCK cells as much as 3.6-fold (p < 0.01) . These results demonstrate that phloridzin, in contrast to previous notions, is transported by SGLT1 . In addition, they demonstrate that this and other flavonoid glycosides unexpectedly are efficiently effluxed by both MRP1 and MRP2. J Pharmacol Exp Ther, 2004 Jan, 308(1), 260 - 7 Epub 2003 Oct 20. Role of multidrug resistance protein 2 (MRP2, ABCC2) in alkylating agent detoxification: MRP2 potentiates glutathione S-transferase A1-1-mediated resistance to chlorambucil cytotoxicity; Smitherman PK et al.; Our previous studies have shown that the glutathione S-transferases (GSTs) can operate in synergy with the efflux transporter multidrug resistance protein 1 (MRP1, ABCC1) to confer resistance to the cyto- and genotoxicities of some anticancer drugs and carcinogens . The current study was designed to determine whether the alternative efflux transporter, MRP2 (ABCC2), can also potentiate GST-mediated detoxifications in HepG2 cells . HepG2 cells, which express high-level MRP2 but not MRP1, were stably transduced with GST expression vectors under tetracycline-repressible transcriptional control . MRP2 was able to support GSTA1-1-mediated resistance to chlorambucil (CHB) cytotoxicity in HepG2 cells . Resistance was GST isozyme-specific in that GSTP1a-1a and GSTM1a-1a failed to confer protection from CHB toxicity . Moreover, inhibition of MRP2 with sulfinpyrazone completely reversed GSTA1-1-associated resistance, indicating that MRP2-efflux function is required to potentiate GSTA1-1-mediated resistance . Relative transport by MRP1 versus MRP2 of monoglutathionyl-CHB (CHB-SG) was examined using inside-out plasma membrane vesicles derived from MCF7 cells transduced with MRP1 or MRP2 expression vectors . Both MRP1 and MRP2 transported CHB-SG efficiently, at the levels of protein expressed, with similar Vmax and with Km of 0.39 and 10 microM, respectively . We conclude that detoxification of CHB by GSTA1-1 requires the removal of the glutathione conjugate formed and that either MRP1 or MRP2 can serve this efflux function . These findings have implications for the role of MRP2 in detoxification of alkylating agents in the apical epithelium of liver and kidney where it is highly expressed as well as the role of MRP2 in the emergence of alkylating drug resistance in cancer cells. Neuroscience, 2003, 121(3), 605 - 17 Relationship between expression of multiple drug resistance proteins and p53 tumor suppressor gene proteins in human brain astrocytes; Marroni M et al.; Multiple drug resistance occurs when cells fail to respond to chemotherapy . Although it has been established that the drug efflux protein P-glycoprotein protects the brain from xenobiotics, the mechanisms involved in the regulation of expression of multiple drug resistance genes and proteins are not fully understood . Re-entry into the cell cycle and integrity of the p53 signaling pathway have been proposed as triggers of multiple drug resistance expression in tumor cells . Whether this regulation occurs in non-tumor CNS tissue is not known . Since multiple drug resistance overexpression has been reported in glia and blood vessels from epileptic brain, we investigated the level of expression of multidrug resistance protein, multidrug resistance-associated proteins and lung resistance protein in endothelial cells and astrocytes isolated from epileptic patients or studied in situ in surgical tissue samples by double label immunocytochemistry . Reverse transcriptase-polymerase chain reaction and Western blot analyses revealed that multiple drug resistance, multidrug resistance protein, and lung resistance protein are expressed in these cells . Given that lung resistance proteins have been reported to be preferentially expressed by tumors, we investigated expression of tumor suppressor genes in epileptic cortices . The pro-apoptotic proteins p53 and p21 could not be detected in "epileptic" astrocytes, while endothelial cells from the same samples readily expressed these proteins, as did normal brain astroglia and normal endothelial cells . Other apoptotic markers were also absent in epileptic glia.Our results suggest a possible link between loss of p53 function and expression of multiple drug resistance in non-tumor CNS cells. Exp Cell Res, 2003 Nov 1, 290(2), 177 - 94 The rise of DNA methylation and the importance of chromatin on multidrug resistance in cancer; Baker EK et al.; In recent years, the different classes of drugs and regimens used clinically have provided an improvement in tumour management . However, treatment is often palliative for the majority of cancer patients . Transformed cells respond poorly to chemotherapy mainly due to the development of the multidrug resistance (MDR) phenotype . Response to treatment does not generally result in complete remission and disease cure is uncommon for patients presenting with advanced stage cancer . Successful treatment of cancer requires a clearer understanding of chemotherapeutic resistance . Here, we examine what is known of one of the most extensively studied mechanisms of cellular drug resistance . The human multidrug resistance gene 1 (MDR1) is associated with expression of p-glycoprotein (Pgp) . A transmembrane protein, Pgp acts as an efflux pump and reduces intracellular drug levels and thus its effectiveness as an antitumor agent . The precise mechanism of transcriptional regulation has been unclear due to the complex regulatory nature of the gene . It has become increasingly apparent that trans-activation or genetic amplification is by no means the only mechanism of activation . Consequently, alternative pathways have received more attention in the area of epigenetics to help explain transcriptional competence at a higher level of organization . The goal of this article is to highlight important findings in the field of methylation and explain how they impinge on MDR1 gene regulation . In this review, we cover the current information and postulate that epigenetic modification of MDR1 chromatin influences gene transcription in leukaemia . Finally, we explore transcriptional regulation and highlight recent progress with engineered ZFP's (zinc finger proteins). Mol Genet Metab, 2003 Sep-Oct, 80(1-2), 216 - 26 Alternative splicing within the ligand binding domain of the human constitutive androstane receptor; Savkur RS et al.; The human constitutive androstane receptor (hCAR; NR1I3) is a member of the nuclear receptor superfamily . The activity of hCAR is regulated by a variety of xenobiotics including clotrimazole and acetaminophen metabolites . hCAR, in turn, regulates a number of genes responsible for xenobiotic metabolism and transport including several cytochrome P450s (CYP 2B5, 2C9, and 3A4) and the multidrug resistance-associated protein 2 (MRP2, ABCC2) . Thus, hCAR is believed to be a mediator of drug-drug interactions . We identified two novel hCAR splice variants: hCAR2 encodes a receptor in which alternative splice acceptor sites are utilized resulting in a 4 amino acid insert between exons 6 and 7, and a 5 amino acid insert between 7 and 8, and hCAR3 encodes a receptor with exon 7 completely deleted resulting in a 39 amino acid deletion . Both hCAR2 and hCAR3 mRNAs are expressed in a pattern similar to the initially described MB67 (hCAR1) with some key distinctions . Although the levels of expression vary depending on the tissue examined, hCAR2 and hCAR3 contribute 6-8% of total hCAR mRNA in liver . Analysis of the activity of these variants indicates that both hCAR2 and hCAR3 lose the ability to heterodimerize with RXR and lack transactivation activity in cotransfection experiments where either full-length receptor or GAL4 DNA-binding domain/CAR ligand binding domain chimeras were utilized . Although the role of hCAR2 and hCAR3 is currently unclear, these additional splice variants may provide for increased diversity in terms of responsiveness to xenobiotics. Biochemistry, 2003 Oct 28, 42(42), 12163 - 73 A mechanism for P-glycoprotein-mediated apoptosis as revealed by verapamil hypersensitivity; Karwatsky J et al.; Selection of tumor cell lines with anticancer drugs has led to the appearance of multidrug-resistant (MDR) subclones with P-glycoprotein 1 (P-gp1) expression . These cells are cross-resistant to several structurally and functionally dissimilar drugs . Interestingly, in the process of gaining resistance, MDR cells become hypersensitive or collaterally sensitive to membrane-active agents, such as calcium channel blockers, steroids, and local anaesthetics . In this report, hypersensitivity to the calcium channel blocker, verapamil, was analyzed in sensitive and resistant CHO cell lines . Our results show that treatment with verapamil preferentially induced apoptosis in MDR cells compared to drug-sensitive cells . This effect was independent of p53 activity and could be inhibited by overexpression of the Bcl-2 gene . The induction of apoptosis by verapamil had a biphasic trend in which maximum cell death occurred at 10 microM, followed by improved cell survival at higher concentrations (50 microM) . We correlated this effect to a similar biphasic trend in P-gp1 ATPase activation by verapamil in which low concentrations of verapamil (10 microM) activated ATPase, followed by inhibition at higher concentrations . To confirm the relationship between apoptosis and ATPase activity, we used two inhibitors of P-gp1 ATPase, PSC 833 and ivermectin . These ATPase inhibitors reduced hypersensitivity to verapamil in MDR cells . In addition, low concentrations of verapamil resulted in the production of reactive oxygen species (ROS) in MDR cells . Taken together, these results show that apoptosis was preferentially induced by P-gp1 expressing cells exposed to verapamil, an effect that was mediated by ROS, produced in response the high ATP demand by P-gp1. Pharm Res, 2003 Sep, 20(9), 1394 - 400 Involvement of multidrug resistance associated protein 1 (Mrp1) in the efflux transport of 17beta estradiol-D-17beta-glucuro