Ann N Y Acad Sci, 2001 Dec, 953, 165 - 84 DOTS and DOTS-plus: not the only answer; Farmer P; Multidrug-resistant tuberculosis is already a global pandemic, with focal "hot spots" of ongoing transmission . Although DOTS (directly observed treatment, short course) chemotherapy is the goal of global tuberculosis control, short-course chemotherapy will not cure multidrug-resistant tuberculosis . In settings of high transmission of multidrug-resistant tuberculosis, "DOTS plus" (a complementary DOTS-based strategy with provisions for treating multidrug-resistant tuberculosis) is warranted . DOTS-plus project implementation to date reveals important clinical, epidemiological, and economic lessons . Community-based strategies designed to enhance local capacity are cost effective and make it possible to meet new medical challenges. Hepatol Res, 2002 Jan, 22(1), 58 - 64 Increased expression of multidrug resistance-associated protein 1 (mrp1) in hepatocyte basolateral membrane and renal tubular epithelia after bile duct ligation in rats; Pei QL et al.; Components of the multidrug resistance-associated protein (mrp) family mediate the adenosine triphosphate (ATP)-dependent transport of conjugated organic anions in the liver . Of these, mrp1 and mrp2 have been shown to have similar substrate specificity and nucleotide sequence . The intracellular localization and distribution of mrp1 under normal condition and cholestasis have not been as yet completely elucidated . To clarify this point, in the present study we evaluated the intracellular localization of mrp1 in rat liver and kidney after bile duct ligation (BDL) . Bile duct was ligated in Wistar rats . Sequential staining of mrp1 by immunofluorescence was carried out in rat liver and kidneys 1, 3, and 5 days after bile duct ligation using confocal laser scanning microscopy . Weak granular staining of mrp1 was observed in cytoplasm of control rat hepatocytes . In addition to increased cytoplasm staining of mrp1, belt-and granule-like staining of mrp1 in basolateral membrane of hepatocytes was also shown after BDL . Furthermore, mrp1 immunofluorescence increased over time after BDL . No specific immunoflurescence of mrp1 was detected in control rat kidney . However, mrp1-positive staining was observed in epithelia of some renal tubules after BDL . This study showed that mrp1 immunofluorescence increased in hepatocyte basolateral membrane and cytoplasm and epithelia of some renal tubules after BDL . This increased mrp1 expression may be an adaptive response to impairment of hepato-biliary organic anion transport during obstructive cholestasis. J Bioenerg Biomembr, 2001 Dec, 33(6), 503 - 11 The role of half-transporters in multidrug resistance; Bates SE et al.; ATP-binding cassette proteins comprise a superfamily of transporter proteins, a subset of which have been implicated in multidrug resistance . Although P-glycoprotein was described over 15 years ago, the recent expansion in the number of transporters identified has prompted renewed interest in the role of drug transporters in clinical drug resistance . These newly identified transporters include additional members of the MRP family, ABC2, and a new half-transporter, MXR/BCRP/ABCP1 . This half-transporter confers high levels of resistance to mitoxantrone, anthracyclines, and the camptothecins SN-38 and topotecan . At 72 kDa, MXR localizes to the plasma membrane in cells which highly overexpress the protein either through gene amplification or though gene rearrangement . Future studies will be aimed at identifying an inhibitor, and attempting to translate recognition of this new transporter into a target for anticancer treatment. J Bioenerg Biomembr, 2001 Dec, 33(6), 481 - 91 The mechanism of action of multidrug-resistance-linked P-glycoprotein; Sauna ZE et al.; P-glycoprotein (Pgp), the ATP-binding cassette (ABC) transporter, confers multidrug resistance to cancer cells by extruding cytotoxic natural product amphipathic drugs using the energy of ATP hydrolysis . Our studies are directed toward understanding the mechanism of action of Pgp and recent work deals with the assessment of interaction between substrate and ATP sites and elucidation of the catalytic cycle of ATP hydrolysis . The kinetic analyses of ATP hydrolysis by reconstituted purified Pgp suggest that ADP release is the rate-limiting step in the catalytic cycle and the substrates exert their effect by modulating ADP release . In addition, we provide evidence for two distinct roles for ATP hydrolysis in a single turnover of Pgp, one in the transport of drug and the other in effecting conformational changes so as to reset the transporter for the next catalytic cycle . Detailed kinetic measurements determined that both nucleotide-binding domains behave symmetrically and during individual hydrolysis events the ATP sites are recruited in a random manner . Furthermore, only one nucleotide site hydrolyzes ATP at any given time, causing (in this site) a conformational change that drastically decreases (>30-fold) the affinity of the second site for ATP-binding . Thus, the blocking of ATP-binding to the second site while the first one is in catalytic conformation appears to be the basis for the alternate catalytic cycle of ATP hydrolysis by Pgp, and this may be applicable as well to other ABC transporters linked with the development of multidrug resistance. J Bioenerg Biomembr, 2001 Dec, 33(6), 469 - 74 ABC proteins of Leishmania; Legare D et al.; ABC proteins were first characterized in the protozoan parasite Leishmania while studying mechanisms of drug resistance . PGPA is involved in resistance to arsenite and antimonite and it most likely confers resistance by sequestering metal-thiol conjugates into an intracellular vesicle . PGPA is part of gene family with at least four more members which are in search of a function . Leishmania also contains a P-glycoprotein, homologous to the mammalian MDR1, that is involved in multidrug resistance . The ongoing genome project of Leishmania has pinpointed several novel ABC transporters and experiments are carried out to study the function of the ABC proteins in drug resistance and in host-pathogen interactions. Bone Marrow Transplant, 2001 Dec, 28(12), 1171 - 3 Pneumonia and sepsis due to fluoroquinolone-resistant Capnocytophaga gingivalis after autologous stem cell transplantation; Geisler WM et al.; Human oral Capnocytophaga species have been only rarely described as a cause of sepsis in patients following stem cell or marrow transplantation, and pneumonia has not been reported in this setting . In addition, fluoroquinolone resistance is rarely seen in these species, and has never been reported in C . gingivalis . We report a case of pneumonia (confirmed by culture of bronchoalveolar lavage fluid) and sepsis due to fluoroquinolone- resistant Capnocytophaga gingivalis in a patient following autologous stem cell transplantation, who responded to treatment with linezolid and metronidazole . Capnocytophaga infections should be considered in patients with fever following stem cell or marrow transplantation, especially those with neutropenia and mucositis . Susceptibility testing is needed given the existence of multidrug-resistant isolates. Biochem J, 2002 Feb 1, 361(Pt 3), 497 - 503 Role of glutathione in the multidrug resistance protein 4 (MRP4/ABCC4)-mediated efflux of cAMP and resistance to purine analogues; Lai L et al.; Multidrug resistance protein 4 (MRP4/ABCC4) is a member of the MRP subfamily, which in turn is a member of the superfamily of ATP-binding-cassette (ABC) transporters . Within the MRP subfamily, ABCC4,ABCC5 (MRP5), ABCC11 (MRP8) and ABCC12 (MRP9) have similar predicted membrane topologies . All lack the additional transmembrane domain, TMD(0), which is present in the other MRPs . Using cells stably overexpressing ABCC4, this study shows that ABCC4 exports GSH . ABCC4 also facilitates the efflux of cAMP . Depletion of intracellular GSH with DL-buthionine-(S,R)-sulphoximine led to decreased export of cAMP and a corresponding increase in intracellular cAMP was observed . ABCC4 also mediates resistance to purine analogues 9-(2-phosphonylmethoxyethyl)-adenine and 6-thioguanine . This resistance can be reversed by the presence of DL-buthionine-(S,R)-sulphoximine . We conclude that as well as nucleotide and nucleoside analogues, ABCC4 can mediate the export of GSH . In addition, GSH plays an important role in the function of ABCC4 . Depletion of intracellular GSH adversely affects the export of cAMP by ABCC4 . Resistance to nucleoside analogues is also adversely affected by depletion of cellular GSH. Clin Cancer Res, 2002 Jan, 8(1), 221 - 32 Differences in therapeutic indexes of combination metronomic chemotherapy and an anti-VEGFR-2 antibody in multidrug-resistant human breast cancer xenografts; Klement G et al.; One of the greatest barriers to the treatment of cancer with chemotherapeutic drugs is acquisition of drug resistance . This includes multidrug resistance mediated by P-glycoprotein (Pgp) to multiple lipophilic natural compounds such as taxanes, doxorubicin (Adriamycin), and vinblastine . The considerable efforts made thus far to reverse this and other types of drug resistance have had very limited success . We report here that a variety of orthotopic human breast cancer xenografts selected for high levels of Pgp and multidrug resistance respond in a significant and durable manner to different continuous low-dose (e.g., one-tenth the maximum tolerated dose of chemotherapy) chemotherapy regimens, when used in combination with an antivascular endothelial cell growth factor (anti-VEGF) receptor-2 (flk-1)-neutralizing antibody (DC101) . The Pgp substrates paclitaxel (Taxol), Adriamycin, and vinblastine were all effective using this type of combination treatment, although the chemotherapy protocols showed little or no effect as monotherapies . Similar results were also obtained using cisplatinum (a non-Pgp substrate drug) against cisplatinum-resistant tumors . Evidence of significant tumor cell death by the combination treatment was detected within 3 weeks of initiation of therapy by histopathological analysis, in the absence of shrinkage of tumor mass . There were, however, marked differences in the cumulative toxicity of long-term regimens of Adriamycin and cisplatinum, where toxicity was observed, when compared with the tubulin inhibitors, vinblastine and Taxol, where it was not . We conclude that vascular-targeting protocols involving frequent administration of very low doses of certain chemotherapeutic drugs can provide a stable and safe way to circumvent multidrug resistance in established orthotopically growing tumors, as long as these are used in combination with a second antiangiogenic drug, in this case, anti-VEGFR-2 blocking antibodies. Clin Cancer Res, 2002 Jan, 8(1), 22 - 8 The multidrug resistance transporter ABCG2 (breast cancer resistance protein 1) effluxes Hoechst 33342 and is overexpressed in hematopoietic stem cells; Kim M et al.; The human ATP-binding cassette superfamily G (White) member 2 (ABCG2) gene and its murine homologue breast cancer resistance protein 1 (Bcrp1) are recently described ATP-binding cassette transporters associated with drug resistance in tumor cell lines, including the MCF-7 cell line, selected for its resistance to mitoxantrone (MCF-7/MitoR) . Infection of MCF-7 cells with the retroviral vector containing ABCG2 cDNA (G1-ABCG2) resulted in cells (MCF-7/ABCG2) that were resistant to mitoxantrone at levels similar to those observed in MCF-7/MitoR cells . Previous studies have shown that pluripotent hematopoietic stem cells overexpress the multidrug-resistant transport (MDR1) gene and efflux rhodamine, a substrate for the MDR1 transporter . Other studies have identified a primitive hematopoietic stem cell population, or side population (SP) cells, which are identified by their efflux of the fluorescent dye, Hoechst 33342 . In an attempt to identify the transport genes responsible for this phenotype, we examined the uptake of Hoechst 33342 into MCF-7, MCF-7/MitoR, and MCF-7 cells infected with a retroviral vector expressing the ABCG2 gene (MCF-7/ABCG2) . MCF-7/MitoR cells as well as MCF-7/ABCG2 cells demonstrated lower levels of Hoechst 33342 uptake compared with the parental MCF-7 cells . We also examined the level of the mouse Bcrp1 RNA in SP cells and non-SP cells isolated from mouse hematopoietic cells . Mouse SP cells expressed relatively high levels of Bcrp1 mRNA relative to non-SP cells . These results suggest that Hoechst 33342 is a substrate for the ABCG2 transporter and that ABCG2/Bcrp1 expression may serve as a marker for hematopoietic stem cells in hematopoietic cells. J Med Assoc Thai, 2001 Sep, 84(9), 1241 - 5 In vitro susceptibility testing of levofloxacin and ofloxacin by microtiter plate Alamar blue against multidrug and non multidrug resistant Mycobacterium tuberculosis in Thailand; Pracharktam R et al.; Antituberculous drugs for current therapy of multidrugs resistant tuberculosis (MDR-TB) are limited . The in vitro susceptibility of Mycobacterium tuberculosis (MTB) as well as MDR-TB with other antibiotic drugs were determined in order to find alternative drugs for the treatment of MDR-TB . Forty-seven MDR-TB and 62 MTB of clinical isolates were tested against levofloxacin and ofloxacin . The MDR-TB at the MIC90 of levofloxacin and ofloxcain were 1 microg/ml and 2 microg/ml, respectively . Of these MTB, the MIC90 of both drugs were 0.5 microg/ml and 1 microg/ml, respectively . It seemed that levofloxacin MICs of both MDR-TB and MTB were one dilution less than ofloxcin . The promising activity of ofloxacin and levofloxacin against MDR-TB and MTB suggest that both drugs could be used as second-line drugs for MDR-TB or as a good alternative antituberculous drug for patients who have intolerance to the first line drug. Zhong Yao Cai, 2001 Sep, 24(9), 655 - 7 {Study on active constituents of traditional Chinese medicine reversing multidrug resistance of tumor cells in vitro}; Zhang H et al.; OBJECTIVE: To screen drugs reversing multidrug resistance of tumor cells from active constituents of traditional Chinese medicine and to study the reversal action . METHODS: The kill effects of the drugs on tumor cell lines in vitro were determined with MTT method . The Jin's formula was used to analyse the effect of drug combination . RESULTS: 5 micrograms/ml rhynchophylline, 2 micrograms/ml jatrorrhizine and 1.25 micrograms/ml indirulin could reverse multidrug resistance for vincristine on KBv200 cell line by 16.8, 5.1 and 4 fold respectively . 1.56-12.5 micrograms/ml curcumine combining with vincristine could sensitize antitumor effect both on KB and KBv200 cell lines . CONCLUSION: All rhynchophylline, jatrorrhizine and indirulin could reverse multidrug resistance for vincristine on KBv200 cell line . Curcumine combinating vincristine could sensitize antitumor effect both on kB and kBv200 cell lines. J Virol, 2002 Feb, 76(4), 1753 - 61 Persistence and fitness of multidrug-resistant human immunodeficiency virus type 1 acquired in primary infection; Brenner BG et al.; This study examines the persistence and fitness of multidrug-resistant (MDR) viruses acquired during primary human immunodeficiency virus infection (PHI) . In four individuals, MDR infections persisted over the entire study period, ranging from 36 weeks to 5 years, in the absence of antiretroviral therapy . In stark contrast, identified source partners in two cases showed expected outgrowth of wild-type (WT) virus within 12 weeks of treatment interruption . In the first PHI case, triple-class MDR resulted in low plasma viremia (1.6 to 3 log copies/ml) over time compared with mean values obtained for an untreated PHI group harboring WT infections (4.1 to 4.3 log copies/ml) . Increasing viremia in PHI patient 1 at week 52 was associated with the de novo emergence of a protease inhibitor-resistant variant through a recombination event involving the original MDR virus . MDR infections in two other untreated PHI patients yielded viremia levels typical of the untreated WT group . A fourth patient's MDR infection yielded low viremia (<50 to 500 copies/ml) for 5 years despite his having phenotypic resistance to all antiretroviral drugs in his treatment regimen . In two of these PHI cases, a rebound to higher levels of plasma viremia only occurred when the M184V mutation in reverse transcriptase could no longer be detected and, in a third case, nondetection of M184V was associated with an inability to isolate virus . To further evaluate the fitness of MDR variants acquired in PHI, MDR and corresponding WT viruses were isolated from index and source partners, respectively . Although MDR viral infectivity (50% tissue culture infective dose) was comparable to that observed for WT viruses, MDR infections in each case demonstrated 2-fold and 13- to 23-fold reductions in p24 antigen and reverse transcriptase enzymatic activity, respectively . In dual-infection competition assays, MDR viruses consistently demonstrated a marked replicative disadvantage compared with WT virus . These results indicate that MDR viruses that are generated following PHI can establish persistent infections as dominant quasispecies despite their impaired replicative competence. Zhonghua Yi Xue Za Zhi, 2001 Mar 25, 81(6), 328 - 31 {Alteration of subcellular distribution of protein kinase C isoforms in swelling-activated multi-drug-resistant gastric cancer cells and its significance}; Han Y et al.; OBJECTIVE: To study the alteration of expression and subcellular distribution of classical protein kinase (cPKC) isoforms in gastric cancer cells SGC7901 and their multidrug-resistant cell line SGC7901/VCR under condition of swelling activation and to study the significance of such alterations . METHODS: Immuno-fluorescence technique and Western Blotting were used to determine the expression and subcellular distribution of cPKC isoforms in gastric cancer cells SGC7901 and its multidrug-resistant cell line SGC7901/VCR under normal condition and during continuous hypotonic perfusion . The co-expression of p-glycoprotein (Pgp) and protein kinase C alpha (PKC alpha) was visualized by immunofluorescence double labeling and laser confocus microscopy . RESULTS: Under the normal condition, the four isoenzymes of cPKC were expressed in both the cell membrane and the nuclei of the gastric cancer cells SGC7901 and their multidrug-resistant cell line SGC7901/VCR; PKC alpha was strongly positively expressed in the multidrug-resistant cells and positively expressed in the drug-sensitive cells; PKC beta I and PKC beta II were positively expressed in both drug-resistant and drug-sensitive cells, and PKC gamma was strongly positively expressed in both cells . In drug-resistant cell line, cell-swelling and translocation of PKC alpha and PKC gamma were observed ten minutes after continuous hypotonic perfusion . Thirty minutes after the perfusion, almost all the PKCalpha was translocated into the cell membrane of SGC7901/VCR, part of the PKC gamma was translocated into the nucleus, and the cell volume increased to two to three times as much as before . Sixty minutes later, the subcellular distribution of PKCalpha and PKC gamma and the cell volume returned to normal . In drug-sensitive cells, 10 approximately 20 minutes after the continuous hypotonic perfusion nearly all the PKCalpha was translocated into the cell membrane, part of PKC gamma was translocated into the cell membrane, and the cell volume increased to two to three times as much as before . Forty minutes later, PKCalpha and PKCgamma had basically returned to normal . The subcellular distribution of PKCbeta I and PKC beta II remained unchanged in both SGC7901 and SGC7901/VCR . Co-expression of Pgy and PKCalpha was observed in both drug-sensitive and drug-resistant cells, especially in the former . CONCLUSION: Only PKCalpha and PKC gamma isoforms play an important role in the regulation of signal transduction of Pgy and cell volume under continuous perfusion and are related to the expression of PKC alpha and Pgy . PKC beta I and PKC beta II may have nothing to do with such processes. Zhonghua Yi Xue Za Zhi, 2000 Mar, 80(3), 219 - 21 {Reversal of multidrug resistance in lung adenocarcinoma-resistant cell line A549/R by mdr1 antisense oligodeoxynucleotides in vitro}; Chen L et al.; OBJECTIVE: To investigate the possibility of reversion of multidrug resistance (MDR) in lung adenocarcinoma-resistant cell line A549/R by mdr1 antisense oligodeoxynucleotide . METHODS: A 15-mer phosphorothioate antisense oligodeoxynucleotide (ATCCATCCCGACCTC), complementary to -9 approximately + 6 in mdr1 cDNA sequence, was synthesized . Meanwhile, sense sequence (GAGGTCGGGATGGAT) was taken as control . Both antisense and sense oligodeoxynucleotides were transduced to A549/R cell line by lipofectin . The mdr1 mRNA, expression of Pgp, cellular rhodamine accumulation and sensitivity to daunorubicin were detected in antisense and sense oligodeoxynucleotides treated cells, using RT-PCR, flow cytometry, rhodamine test and MTT method . RESULTS: Treatment with antisense oligodeoxynucleotide in A549/R cells led to a decrease in mdr1 mRNA and Pgp expression, an increase in rhodamine cellular accumulation, and a 20-fold increase of sensitivity to doxorubicin compared with those treated with sense oligodeoxynucleotide or control cells . CONCLUSION: The mdr1 antisense oligodeoxynucleotide possesses an effect of reversing MDR in lung adenocarcinoma-resistant cell A549/R by inhibiting mdr1 transcription and Pgp expression. Zhonghua Nei Ke Za Zhi, 1999 Nov, 38(11), 760 - 3 {The clinical significance of lung resistance-related protein gene (lrp), multidrug resistance-associated protein gene (mrp) and mdr-1/p170 expression in acute leukemia}; Zhao Y et al.; OBJECTIVE: To evaluate the relationship between lrp, mrp, mdr-1/p170 and multidrug resistance in acute leukemia (AL) . METHODS: 85 AL patients were divided into three groups: untreated (A), complete remission (B) and relapsed/refractory (C) . The expression of lrp, mrp and mdr-1 mRNA was detected with RT-PCR assay and that of p170 measured with immunocytochemistry . RESULTS: The frequency of lrp gene expression in ANLL A, B and C group was 11.11%, 9.09% and 36.36%, in ALL A, B, C group it was 0%, 20.00% and 46.67%; the frequency of mrp gene expression in ANLL A, B, C group was 44.44%, 9.09% and 59.09%, in ALL A, B, C group it was 28.57%, 20.00% and 53 . 33%; the frequency of mdr-1 gene expression in ANLL A, B, C group was 0%, 4.54% and 59.09%, in ALL A, B, C group it was 0%, 0% and 33.33%; p170 expression in ANLL C group was (9.45 +/- 14.66) %, it was the highest value in the three groups; statistics showed that there was no correlationship among the expressions of lrp, mrp and mdr-1 gene, P > 0.05; patients with lrp and mdr-1 expression had a lower complete remission (CR) percentage than those who had not in the untreated group; the combination of lrp, mrp and mdr-1 gene detection turned out to be a more sensitive, specific and accurate way in evaluation of multidrug resistance (MDR) . CONCLUSION: Overexpression of one or more genes of lrp, mrp and mdr-1/p170 is associated with MDR in AL . Expression of lrp, mrp and mdr-1/p170 is good indicators in clinical MDR . Two or three factors of lrp, mrp and mdr-1 are more valuable in the evaluation of MDR than any one of these three factors . The mechanisms of mrp, lrp and mdr-1 causing MDR are different, it means that the mechanisms of MDR are complicated the combination of lrp, mrp and mdr-1/p170 detection may be the best way to evaluate MDR. Zhonghua Nei Ke Za Zhi, 1999 Jun, 38(6), 373 - 6 {Reversal of multidrug resistance of leukemia cell line in vitro by antisense phosphorothioate oligonucleotide}; Chen Y et al.; OBJECTIVE: To investigate the effectiveness of 14 mer antisense phosphorothiaoate oligonucleotide (AS-SODN) complementary to the published multidrug resistance gene (mdr(1) gene) sequence to reverse multidrug resistance of leukemia cell line . METHODS: 50% inhibitory concentration (IC(50)) of K562 cell line resistant to adriamycin (K562/ADM cell line) was determined by the tetrazolium dye, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method, the concentration of daunorubicin (DNR) in the cell by flow cytometry, the level of P170 by immunohistochemical staining technique and the level of mdr(1)-mRNA by half-quantitative RT-PCR (the ratio of mdr(1)/beta(2)-MG) . RESULTS: Treatment of K562/ADM cell line with 2 micromol/L AS-SODN reduced the level of both the mdr(1)-mRNA and P170 . The ratio of mdr(1)/beta(2)-MG reduced from (2.07 +/- 0.16) to (1.57 +/- 0.14), and positive rate of P170 expression decreased from (98.26 +/- 1.35)% to (18.30 +/- 6.50)% . Accordingly, the concentration of DNR in cell increased . With these findings, IC(50) to ADM reduced from 25.72 mg/L to 6.97 mg/L and relative effciency of modulation was 73.01% . CONCLUSION: Antisense oligonucleotide targeting mdr(1) gene can reduce md(1)-mRNA, block P170 expression so as to increase the sensitivity of K562/ADM cell line to chemotherapy drugs. Zhonghua Nei Ke Za Zhi, 1999 Jan, 38(1), 47 - 9 {Expression and clinical study of multidrug resistance gene and multidrug resistance associated protein gene in acute leukemia}; Ma J et al.; OBJECTIVE: To evaluate the relationship between the expression of multidrug resistance gene (mdr1) or multidrug resistance-associated protein gene (MRP) and the prognosis in patients with acute leukemia (AL) . METHODS: The expression of mdr1 and MRP were measured in 55 patients with AL by reverse transcription polymerase chain reaction (RT-PCR) . RESULTS: The mdr1 and MRP gene expression levels in the relapsed AL and the blastic phase of CML group (0.735 +/- 0.249, 1.157 +/- 0.447) were significantly higher than those in the untreated group (0.408 +/- 0.186, 0.465 +/- 0.253) (P < 0.01) . The complete remission (CR) rate in high mdr1 and MRP expression group was significantly lower than that in low mdr1 and MRP expression group (P < 0.01) in a follow up of 40 AL patients . CONCLUSION: Increased expression of mdr1 and MRP gene might be an important factor for predicting drug resistance, relapse and unfavorable prognosis in AL patients. Stem Cells, 2002, 20(1), 11 - 20 ABC transporters as phenotypic markers and functional regulators of stem cells; Bunting KD; Characterization of molecules with tightly controlled expression patterns during differentiation represents an approach to understanding regulation of hematopoietic stem cell commitment . The multidrug resistance-1 (MDR1) gene product, P-glycoprotein, and the breast cancer resistance protein (BCRP) are expressed differentially during hematopoiesis, with the highest levels in primitive bone marrow stem cell populations that are CD34(low) and CD34(-), respectively . Roles for ATP-binding cassette (ABC) transporter superfamily members in conferring drug resistance have been extensively described . However, recent hematopoietic overexpression studies have begun to reveal previously unknown roles for ABC transporter function in normal and malignant hematopoiesis . Expression of MDR1 and BCRP transporters in the myeloid lineage has been reported in blasts from acute myeloid leukemia, but very low to undetectable in normal myelomonocytic cells . Retroviral-mediated dysregulated expression of the MDR1 transporter resulted in increased hematopoietic repopulating activity and myeloproliferative disease in mice . A distinct functional role for the BCRP transporter as a negative regulator of hematopoietic repopulating activity has recently been demonstrated using the same approach . Additionally, the presence of BCRP expression specifically on hematopoietic side-population stem cells and neural stem/progenitors, makes BCRP an attractive candidate marker for isolation of stem cells with the ability to respond to diverse environmental cues . Regulation of stem cell biology by ABC transporters has emerged as an important new field of investigation . In light of these findings, it will be critical to further characterize this family of proteins in hematopoietic lineage-restricted stem cells and in pluripotent stem cells capable of crossing lineage barriers. J Neurochem, 2002 Jan, 80(1), 64 - 72 P-glycoprotein expression in rat brain endothelial cells: evidence for regulation by transient oxidative stress; Felix RA et al.; During ischaemia/reperfusion, cells of the blood-brain barrier are subjected to oxidative stress . This study uses primary cultured rat brain endothelial cells to examine the effect of such stresses on expression of multidrug transporters . H(2)O(2) up to 500 microm applied to cell monolayers caused a concentration-dependent increase in expression of P-glycoprotein (Pgp) but not of multidrug resistance-associated protein (Mrp1) . Concentrations > 250 microm H(2)O(2) decreased cell viability . Application of 100 microm H(2)O(2) caused a significant increase after 48 h in Pgp functional activity, as assessed from {(3)H}vincristine accumulation experiments . At this concentration, H(2)O(2) produced a transient increase within 10 min followed by a sustained decrease in levels of intracellular reactive oxygen species (iROS), detectable by flow cytometry . Reoxygenation of cell monolayers after 6 h hypoxia gave rise to a similar transient increase in iROS and this also led to increased Pgp expression by 24 h . Increases were also observed within 4 h after both H(2)O(2) and hypoxia/reoxygenation treatments in mdr1a and mdr1b mRNA . Evidence suggests this was due to enhanced transcription rather than mRNA stabilization . Therefore, oxidative stress, by changing Pgp expression, may affect movement of Pgp substrates in and out of the brain. Antimicrob Agents Chemother, 2002 Feb, 46(2), 443 - 50 Molecular characterization of multidrug-resistant isolates of Mycobacterium tuberculosis from patients in North India; Siddiqi N et al.; The World Health Organization has identified India as a major hot-spot region for Mycobacterium tuberculosis infection . We have characterized the sequences of the loci associated with multidrug resistance in 126 clinical isolates of M . tuberculosis from India to identify the respective mutations . The loci selected were rpoB (rifampin), katG and the ribosomal binding site of inhA (isoniazid), gyrA and gyrB (ofloxacin), and rpsL and rrs (streptomycin) . We found known as well as novel mutations at these loci . Few of the mutations at the rpoB locus could be correlated with the drug resistance levels exhibited by the M . tuberculosis isolates and occurred with frequencies different from those reported earlier . Missense mutations at codons 526 to 531 seemed to be crucial in conferring a high degree of resistance to rifampin . We identified a common Arg463Leu substitution in the katG locus and certain novel insertions and deletions . Mutations were also mapped in the ribosomal binding site of the inhA gene . A Ser95Thr substitution in the gyrA locus was the most common mutation observed in ofloxacin-resistant isolates . A few isolates showed other mutations in this locus . Seven streptomycin-resistant isolates had a silent mutation at the lysine residue at position 121 . While certain mutations are widely present, pointing to the magnitude of the polymorphisms at these loci, others are not common, suggesting diversity in the multidrug-resistant M . tuberculosis strains prevalent in this region . Our results additionally have implications for the development of methods for multidrug resistance detection and are also relevant in the shaping of future clinical treatment regimens and drug design strategies. Antimicrob Agents Chemother, 2002 Feb, 46(2), 344 - 9 Involvement of multidrug resistance-associated protein 2 in intestinal secretion of grepafloxacin in rats; Naruhashi K et al.; We investigated the contribution of multidrug resistance-associated protein 2 (MRP2) to the secretory transport of grepafloxacin and compared its functional role with that of P-glycoprotein (P-gp) by using Sprague-Dawley rats (SDRs) and Eisai hyperbilirubinemic rats (EHBRs), in which MRP2 is hereditarily defective . In intestinal tissue from SDRs mounted in Ussing chambers, the level of transport in the direction from the serosal layer to the mucosal layer was twofold greater than that in the direction from the mucosal layer to the serosal layer . This secretory transport of grepafloxacin was diminished by both probenecid, an MRP2 inhibitor, and cyclosporine, a P-gp inhibitor . In intestinal tissue from EHBRs, the secretory transport of grepafloxacin was lower than that in intestinal tissue from SDRs and was inhibited by cyclosporine but not by probenecid . The absorption of grepafloxacin from intestinal loops in SDRs was in the order of duodenum > jejunum > ileum and was increased by cyclosporine but not by probenecid . The absorption in EHBRs was not higher than that in SDRs . The intestinal secretory clearance in SDRs after intravenous administration of grepafloxacin was shown to be greater for the ileum than for the duodenum, which is in good agreement with the previously reported regional expression profile of MRP2 mRNA . The intestinal secretory clearance was lower in EHBRs than in SDRs . Accordingly, in addition to P-gp, MRP2 might play a role in the secretory transport of grepafloxacin . The function of MRP2 in facilitating grepafloxacin transport in the secretory direction is more pronounced both in vitro and in vivo, while the restriction of entry from the lumen into the cell by MRP2 seems to be negligible, compared with that by P-gp, in the case of grepafloxacin. Breast Cancer, 2001, 8(4), 333 - 8 Resistant mechanisms of anthracyclines--pirarubicin might partly break through the P-glycoprotein-mediated drug-resistance of human breast cancer tissues; Kubota T et al.; Juliano and Ling initially reported the expression of a 170 kDa glycoprotein in the membrane of Chinese hamster ovarian cells in 1976, and named this glycoprotein P-glycoprotein (P-gp) based on its predicted role of causing "permeability" of the cell membrane . After much research on anthracycline-resistance, this P-gp was finally characterized as a multidrug-resistant protein coded by the mdr1 gene . Multidrug resistance associated protein (MRP) was initially cloned from H69AR, a human small cell-lung carcinoma cell line which is resistant to doxorubicin (DXR) but does not express P-gp . MRP also excretes substrates through the cell membrane using energy from ATP catabolism . The substrate of MRP is conjugated with glutathione before active efflux from cell membrane . Recently, membrane transporter proteins were re-categorized as members of "ATP-Binding Cassette transporter"(ABC-transporter) superfamily, as shown at and A total of ABC transporters have been defined, and MDR1 and multidrug resistance associated protein 1 (MRP1) were reclassified as ABCB1 and ABCC1, respectively . Their associated superfamilies include 11 and 13 other protein, in addition to ABCB and ABCC, respectively . Lung resistance-related protein (LRP) is not a member of the superfamily of ABC transporter proteins, because it shows nuclear membrane expression and transports substrate between nucleus and cytoplasm . LRP was initially cloned from a non-small cell lung carcinoma cell line, SW1573/2R120 which is resistant to DXR, vincristine, etoposide and gramicidin D and does not express P-gp . The mechanisms of resistance remains unclear, and why some resistant cell lines express P-gp and others express MRP and/or LRP is likewise unclear. Int J Oncol, 2002 Feb, 20(2), 255 - 60 Comparative genomic hybridization study of genetic changes associated with vindesine resistance in esophageal carcinoma; Obara K et al.; The acquisition of drug-resistance is a major problem for cancer patients undergoing chemotherapy . To clarify genetic alterations in cancer cells that develop drug-resistance, comparative genomic hybridization (CGH) was applied to esophageal squamous cell carcinoma cell lines (SH-1V1, SH-1V2, SH-1V4 and SH-1V8) and chemoresistance-related genes in altered chromosomal regions were evaluated . These cell lines were derived from the parental SH-1 cell line, after multiple steps of selection by an increasing exposure to vindesine . SH-1V8 cells were strongly resistant to vindesine . DNA copy number at 16p which includes the MRP (multidrug resistance related protein) gene was markedly increased in all cell lines examined . Increased DNA copy numbers were found at the regions of 5q31-32, 10q11.1-23, and 14q32-qter in SH-1V8 cells that acquired resistance to other drugs as well . Both SH-1V4 and SH-1V8 showed increased DNA copy numbers at 7q11.1-22, 16q12.1-qter, 19p13.2-13.3, 19q11-13.2 and 20q13.1-qter . The chromosomal region of 7q11.1-22 including MDR-1 (multidrug resistance-1) gene was highly amplified in SH-1V4 and SH-1V8 . Amplification of the MRP region suggests the prerequisite of developing resistance to vindesine, and further amplification of MDR-1 may play a critical role in acquiring drug-resistance . Several unknown genes related to the induction of chemoresistance might be concealed in other altered chromosomal regions. Respiration, 2001, 68(6), 590 - 4 Natural killer cell activity in multidrug-resistant pulmonary tuberculosis; Yildiz P et al.; BACKGROUND: Multidrug-resistant pulmonary tuberculosis (MDRTB), a major problem in developing countries, may result from either insufficiency of host cellular immune response or mycobacterial mechanisms which has been more intensively investigated so far . OBJECTIVES: The aim of the study was to investigate natural killer cell activity (NKA) and T lymphocyte subsets in HIV- patients with secondary MDRTB . Methods: 20 male patients with MDRTB (mean age 38 +/- 8 years), 15 nonresistant tuberculosis male patients (NRTB) (mean age 36 +/- 11 years) and 12 healthy male controls (mean age 35 +/- 8 years) were included . The percentages of CD3+, CD4+, CD8+, CD25+, CD11b+ and CD16+56+ cells were measured by flow-cytometric analysis of peripheral blood lymphocytes (PBL) . NKA was evaluated using the anticandidal index method . RESULTS: The mean tuberculin response was higher in MDRTB and NRTB patients compared to controls (15.4 +/- 3.8, 15.1 +/- 3.3 and 10.9 +/- 2.8 mm, respectively; p < 0.001) . There was no significant correlation between PPD response and PBL subsets or NKA . The percentages of both CD3+ and CD3+CD4+ T lymphocytes were significantly lower in MDRTB (62.4 +/- 12.1 and 33.9 +/- 9.0%) compared to NRTB (70.8 +/- 7.5 and 42.9 +/- 8.6%; p < 0.05) . Patients with MDRTB had significantly lower NKA compared to NRTB and controls (30.9 +/- 11.3, 49.7 +/- 15.5 and 40.0 +/- 8.5%, respectively; p < 0.01) . CONCLUSION: This reduction in NKA may suggest a role for impaired NK function in the pathogenesis of MDRTB in HIV- patients . Med Dosw Mikrobiol, 2001, 53(3), 291 - 5 {Etiologic agents of fungemia in hospitalized patients}; Swoboda-Kopec E et al.; The aim of performed examinations was the analysis of fungi as etiological agents of blood infections in patients hospitalized in surgical wards, internal medicine wards and intensive care units of the Medical Academy Central Clinical Hospital in Warsaw . Blood samples from patients hospitalized in 1997 were examined . Peripheral blood samples were incubated in BacT/Alert system (Organon Teknika, USA) . Positive blood samples were inoculated on Sabouraud medium with chloramphenicol (bioMerieux, France or Oxoid, England) . The time of cultivation was from 48 hours to 7 days at 30 degrees C . Fungal strains were identified by standard mycological procedures with the use of chromogenic medium BBL CHROMagar Candida (Becton Dickinson, USA) and biochemical test ID 32 C (bioMerieux, France) . Susceptibility of strains to antifungal agents was determined by ATB FUNGUS method (bioMerieux, France) . The total number of positive blood cultures in 1997 was 1380 . Forty-two fungal strains were isolated from blood samples (3%) . Strains belonged to the following species: C . albicans (17 isolates), C . parapsilosis (15), C . glabrata (3), melibiosica (2), C . pelliculosa (2), C . guilliermondii (1), C . tropicalis (1) and T . beigelii (1) . Among fungi cultured from patients hospitalized in operative wards dominated C . parapsilosis (11) and C . albicans (10) strains, whereas from patients hospitalized in conservative wards most often C . albicans (6) strains were isolated . Candida strains were mostly susceptible to antifungal agents tested . It was interesting to culture Trichosporon beigelii (T . cutaneum) strain as an etiological agent of fungemia . This strain was multidrug-resistant. Zhonghua Zhong Liu Za Zhi, 2001 Jul, 23(4), 281 - 4 {Differential display of vincristine-resistant proteins in gastric cancer cell line SGC7901}; Wang X et al.; OBJECTIVE: To find out new multidrug-resistant proteins in gastric cancer cells SGC7901 and to explain the new multidrug-resistant mechanism of gastric cancer cells . METHODS: Two-dimensional gel electrophoresis was used with immobilized pH gradients (IPG) to compare the differential expression of multidrug-resistant proteins in gastric cancer cells SGC7901 and Vincristine-resistant SGC7901 cells (SGC7901/VCR) induced by vincristine sulfate . 2-D gels were used to silver stain the protein . RESULTS: Approximately, 680 protein spots were identified in each of the 2-D gel patterns by silver stain . With most of them showing no difference in composition, shape or density, twenty-five proteins were found to differ in quantity (6 higher in SGC7901/VCR cells; 19 higher in 7901 cells) . Five proteins were seen to be unique in one region or the others (3 in SGC7901/VCR cells, 2 in 7901 cells) . The coordinate position of 30 protein spots in the 2-D gels were listed . CONCLUSION: The results suggest that these differential proteins be related to the vincristine-resistant mechanism in human gastric cancer cell line SGC7901/VCR. Zhonghua Zhong Liu Za Zhi, 2001 May, 23(3), 184 - 6 {Subcellular distribution of daunorubicin in the P-glycoprotein-mediated multidrug-resistant cell line K562/ADR}; Gong Y et al.; OBJECTIVE: To examine subcellular distribution of daunorubicin (DNR) in P-glycoprotein-mediated multidrug-resistant cell line K562/ADR and its relation to multidrug resistance . METHODS: The subcellular distribution of DNR in K562/ADR was studied by confocal scanning laser microscopy (CSLM), fluorometry, RT-PCR . Rhodamine 123, NBD-ceramide and neutral red as fluorescent probes to stain the mitochondria, Golgi apparatus and lysosomes respectively were used to identify the subcellular compartments wherein DNR was sequestered . Effect of verapamil, chloroquine and brefeldin A on DNR distribution and accumulation was examined . RESULTS: Compared with the drug-sensitive cell K562/S in which DNR fluorescence diffusely appeared in the nucleus and cytoplasm, DNR in K562/ADR cells was distributed to the perinuclear region and peripheral cytoplasm, It was scenty in the nucleus and other cytoplasmic regions, as suggested by the distribution of Rhodamine123 . Only verapamil, but not chloroquine and brefeldin A, could markedly restore diffuse cytoplasmic and nuclear fluorescence distribution in the resistant cell line . CONCLUSION: Altered subcellular distribution of DNR in drug resistant cell line may participate in the generation of multidrug resistance in which P-glycoprotein plays an important role. Zhonghua Zhong Liu Za Zhi, 2001 Jan, 23(1), 53 - 6 {Immunoelectron microscopic analysis of P-glycoprotein, p53, and Bcl-2 proteins expressions in lung cancer}; Huang X et al.; OBJECTIVE: To determine the ultrastructural localization of P-gp, p53 protein, and Bcl-2 protein in lung cancer cells, their relation to multidrug resistance and possible mechanisms of action . METHODS: Expression of P-gp, p53, and Bcl-2 proteins was examined in 8 NSCLC surgical specimens and 7 SCLC bronchoscopically biopsied specimens using postembedding PAG immunolabelling technique for electron microscopy . RESULTS: P-gp was detected on the cell membrane and the periphery of endoplasmic reticulum (ER) . P53 protein was observed not only in the nuclei associated with heterochromatin but also in the cytosol . Bcl-2 protein immunoreactivity was associated with mitochondria and ER . P-gp, p53, and Bcl-2 were detected in 5(33%), 9(60%), and 4 (26.7%) out of the 15 samples examined, respectively . In 8 normal lung tissues, these three proteins were detected . Of 5 P-gp positive samples 4 were NSCLC, only 1 was SCLC after chemotherapy . CONCLUSION: P-gp, p53, and Bcl-2 proteins are detectable immuno-electron microscopically in lung cancer cells . No correlation in expression existed between of p53 and P-gp, nor did that between p53 and Bcl-2 . The plasma membrane localization of P-gp supports its action as a transmembrane drug efflux pump . P-gp may play a role in MDR in lung cancer. Zhonghua Zhong Liu Za Zhi, 2001 Mar, 23(2), 103 - 6 {Expression and function of protein kinase C-alpha and beta I isoenzymes in drug-resistant gastric cancer cells}; Han Y et al.; OBJECTIVE: To study the expression and function of PKC-alpha and beta I isoenzymes in drug-resistant cells of gastric cancer . METHODS: Two tumor cell lines were used in the study: gastric cancer SGC7901 and its drug-resistant counterpart SGC7901/VCR stepwise-selected by various concentrations of vincristine . The expression of PKC-alpha and beta I isoenzymes in SGC7901 and SGC7901/VCR was detected by immunohistochemistry, laser confocal scanning microscopy and Western blot . The effects of anti-PKC-alpha or beta I antibody on adriamycin accumulation in SGC7901/VCR cells were determined by flow cytometric analysis . RESULTS: SGC7901 cells exhibited positive staining of PKC-alpha . The staining of PKC-alpha in SGC7901/VCR was stronger than that in SGC7901 cells . The higher the concentrations of vincristine, the stronger staining of PKC-alpha was observed on SGC7901/VCR cells . Both SGC7901 and SGC7901/VCR cells were positive for PKC-beta I, but without difference in staining intensity . Comparing with SGC7901, SGC7901/VCR cells showed decreased adriamycin accumulation; the decrease was more marked with the increase in concentrations of vincristine for selection of cells . Increased adriamycin accumulation in SGC7901/VCR was observed when co-incubated with anti-PKC-alpha but not anti-PKC-beta I antibodies . CONCLUSION: PKC-alpha may play a role in multidrug resistance of gastric cancer cells SGC7901/VCR. J Pharm Sci, 2002 Jan, 91(1), 117 - 28 Investigation of the coordinated functional activities of cytochrome P450 3A4 and P-glycoprotein in limiting the absorption of xenobiotics in Caco-2 cells; Tran CD et al.; The coordination of the functional activities of intestinal CYP3A4 and P-gp in limiting the absorption of xenobiotics in Caco-2 cells was investigated . Growing Caco-2 cells were exposed to increasing concentrations of doxorubicin (1-2 microM) in plastic flasks to encourage a subpopulation of cells, that displayed an intrinsically higher multidrug resistance (mdr) phenotype than the parent cells, to survive and grow . Doxorubicin-exposed (hereinafter referred to as type I cells) and nonexposed Caco-2 cells (parent cells) on collagen-coated inserts were also treated with either 0 (control) or 0.25 microM 1alpha,25-dihydroxyvitamin D(3) to promote cellular CYP3A4 expression . Increased P-gp protein expression, as detected by Western blotting, was noted in type I cells (213 +/- 54.35%) compared to that of parent cells (100 +/- 6.05%) . Furthermore, they retained significantly less {(3)H}vincristine sulphate (p < 0.05), a P-gp substrate, after efflux (272.89 +/- 11.86 fmol/mg protein) than the parent cells (381.39 +/- 61.82 fmol/mg protein) . The expression of CYP3A4 in parental cells after 1alpha,25-dihydroxyvitamin D(3) treatment was quantified to be 76.2 +/- 7.6 pmol/mg protein and comparable with that found in human jejunal enterocytes (70.0 +/- 20.0 pmol/mg protein) . Type I cells, however, expressed a very low quantity of CYP3A4 both before and after the treatment that was beyond the minimum detection limit of Western blotting . Functionally, the rates of 1-hydroxylation of midazolam by CYP3A for both cell types ranged from 257.0 +/- 20.0 to 1057.0 +/- 46.0 pmol/min/mg protein . Type I cells, although having a higher P-gp expression and activity comparatively, metabolized midazolam less extensively than the parent cells . The results suggested that there were noncoordinated functional activities of intestinal CYP3A4 and P-gp in Caco-2 cells, although they both functioned independently to minimize intestinal epithelial absorption of xenobiotics . J Acquir Immune Defic Syndr, 2002 Jan 1, 29(1), 11 - 20 Dioxolane guanosine, the active form of the prodrug diaminopurine dioxolane, is a potent inhibitor of drug-resistant HIV-1 isolates from patients for whom standard nucleoside therapy fails; Mewshaw JP et al.; Amdoxovir ({-}-beta-D-2,6-diaminopurine dioxolane {DAPD}) is a nucleoside reverse transcriptase inhibitor (NRTI) with activity against HIV-1 . DAPD is deaminated in vivo by adenosine deaminase to (-)-beta-D-dioxolane guanosine (DXG), a highly active anti-HIV compound . The median 50% effective concentrations (EC 50 ) +/- SD (representing antiviral activity against a laboratory-derived HIV-1 isolate) for DAPD and DXG in peripheral blood mononuclear cells were 4.0 +/- 2.2 micromol/L and 0.25 +/- 0.17 micromol/L, respectively . The 50% cytotoxic dose (CC 50 ) of both DAPD and DXG was >500 micromol/L . Recombinant viruses and clinical isolates of HIV-1 from patients for whom NRTI therapy and/or nonnucleoside reverse transcriptase inhibitor (NNRTI) combination therapies failed remained susceptible to inhibition by DXG (less than fourfold change in EC 50) . Similar analysis showed that recombinant viruses harboring mutations known to confer resistance to NRTIs (zidovudine, lamivudine, and abacavir) and NNRTIs (efavirenz and nevirapine) as well as the multidrug resistance-associated mutation Q151M and double codon insertions (SS and SG) were also susceptible to inhibition by DXG . Resistance to DXG was observed only in recombinant isolates containing the 65R and 151M double mutations . Phenotypic analysis of a site-directed mutant containing only the 151M mutation demonstrated moderate resistance to DXG (<10-fold change in EC 50) . We also examined site-directed mutants containing only L74V or K65R, the characteristic resistance mutations for DXG . The L74V mutant remained susceptible to inhibition by DXG, and the K65R mutant demonstrated moderate resistance to DXG. Blood, 2002 Jan 15, 99(2), 641 - 8 P-glycoprotein-actin association through ERM family proteins: a role in P-glycoprotein function in human cells of lymphoid origin; Luciani F et al.; P-glycoprotein is a 170-kd glycosylated transmembrane protein, expressed in a variety of human cells and belonging to the adenosine triphosphate-binding cassette transporter family, whose membrane expression is functionally associated with the multidrug resistance phenotype . However, the mechanisms underlying the regulation of P-glycoprotein functions remain unclear . On the basis of some evidence suggesting P-glycoprotein-actin cytoskeleton interaction, this study investigated the association of P-glycoprotein with ezrin, radixin, and moesin, a class of proteins that cross-link actin filaments with plasma membrane in a human cell line of lymphoid origin and that have been shown to link other ion-pump-related proteins . To this purpose, a multidrug-resistant variant of CCRF-CEM cells (CEM-VBL100) was used as a model to investigate the following: (1) the cellular localizations of P-glycoprotein and ezrin, radixin, and moesin and their molecular associations; and (2) the effects of ezrin, radixin, and moesin antisense oligonucleotides on multidrug resistance and P-glycoprotein function . The results showed that: (1) P-glycoprotein colocalized and coimmunoprecipitated with ezrin, radixin, and moesin; and (2) treatment with antisense oligonucleotides for ezrin, radixin, and moesin restored drug susceptibility consistently with inhibition of both drug efflux and actin-P-glycoprotein association and induction of cellular redistribution of P-glycoprotein . These data suggest that P-glycoprotein association with the actin cytoskeleton through ezrin, radixin, and moesin is key in conferring to human lymphoid cells a multidrug resistance phenotype . Strategies aimed at inhibiting P-glycoprotein-actin association may be helpful in increasing the efficiency of both antitumor and antiviral therapies. Blood, 2002 Jan 15, 99(2), 507 - 12 The ABCG2 transporter is an efficient Hoechst 33342 efflux pump and is preferentially expressed by immature human hematopoietic progenitors; Scharenberg CW et al.; A promising and increasingly exploited property of hematopoietic stem cells is their ability to efflux the fluorescent dye Hoechst 33342 . The Hoechst-negative cells are isolated by fluorescence-activated cell sorting as a so-called side "population" (SP) of bone marrow . This SP from bone marrow, as well as other tissues, is reported to contain immature stem cells with considerable plasticity . Some cell lines also efflux Hoechst and generate SP profiles . Reverse transcription-polymerase chain reaction (RT-PCR) and efflux inhibition studies with the lung carcinoma cell line, A549, implicated the ABCG2 transporter as a Hoechst efflux pump . Furthermore, it is shown that transient expression of ABCG2 generates a robust SP phenotype in human embryonic kidney (HEK293) cells . The results allow the conclusion that ABCG2 is a potent Hoechst efflux pump . Semiquantitative RT-PCR was used to characterize the developmental pattern of expression of ABCG2 in hematopoiesis . It is expressed at relatively high levels in putative hematopoietic stem cells (isolated as SP, 34+/38- or 34+/KDR+ populations) and drops sharply in committed progenitors (34+/38+, 34+/33+, or 34+/10+) . Expression remains low in most maturing populations, but rises again in natural killer cells and erythroblasts . Comparison of messenger RNA (mRNA) levels for the 3 major multidrug-resistant efflux pumps, MDR1, MRP1, and ABCG2, in bone marrow SP cells reveals that ABCG2 is the predominant form in these cells . These data suggest that ABCG2 contributes significantly to the generation of the SP phenotype in hematopoietic stem cells . Furthermore, the sharp down-regulation of ABCG2 at the stage of lineage commitment suggests that this gene may play an important role in the unique physiology of the pluripotent stem cell. Chin Med J (Engl), 2001 Sep, 114(9), 929 - 32 Reversing drug resistance in the ovarian carcinoma cell line SKOV3/mdr1 in vitro by antisense oligodeoxynucleotides; Pan L et al.; OBJECTIVE: To investigate the effect of multidrug resistance gene 1 (mdr1) antisense oligodeoxynucleotides (ODNs) on reversing multidrug resistance in the drug resistant ovarian carcinoma cell line SKOV3/mdr1 . METHODS: The ovarian carcinoma cell line SKOV3 transducted with a human multidrug resistance gene (mdr1) served as the drug resistant model (SKOV3/mdr1) . The mdr1 antisense ODNs was transfected into SKOV3/mdr1 cells while mediated by lipofectamine . Reverse transcription-polymerase chain reaction (RT-PCR) was used to measure the expression and the amount of the mdr1 mRNA in the cells . The positive rate and function of the mdr1 gene product P-glycoprotein (Pgp) in the mdr1 antisense ODNs treated SKOV3/mdr1 cells were determined by flow cytometry and rhodamine 123 efflux . Drug resistance in the SKOV3/mdr1 cell line was observed by MTT assay and cell colony culture . RESULTS: The mdr1 mRNA level was decreased to about 60% of that of beta-actin after mdr1 antisense ODNs treatment . The Pgp positive rate of mdr1 antisense ODNs treated SKOV3/mdr1 cells decreased from 100% to 52.6% (P < 0.01) . The intracellular rhodamine 123 retention was increased from 9.1% to 33.8% (P < 0.01) . The chemoresistance to taxol decreased to 58% of SKOV3/mdr1 with mdr1 antisense ODN treatment . Compared with SKOV3/mdr1 cells in the control group, under a certain range of drug concentrations, the number of drug resistance colonies in mdr1 antisense ODNs treated SKOV3/mdr1 cells for taxol and doxorubicin decreased by 8.6 +/- 0.8 fold and 3.1 +/- 0.6 fold, respectively . Some non-specific functions during oligodeoxyncleotide treatment was also detected . CONCLUSION: mdr1 expression in the SKOV1/mdr1 cell line was partially inhibited after mdr1 antisense ODNs treatment at the mRNA and protein level, increasing the chemotherapy sensitivity of this drug resistant ovarian carcinoma cell line. Chin Med J (Engl), 2001 Jul, 114(7), 680 - 4 Human stem cell model to study signal transduction and molecular regulation mechanisms in CML; Fan E et al.; OBJECTIVE: To develop a primary human hematopoietic stem/progenitor cell model for chronic myeloid leukemia (CML) and study signal transduction and molecular regulation mechanisms in CML . METHODS: We developed a human model of p210BCR/ABL positive CML by transducing normal human umbilical cord blood CD34+ cells with a retroviral vector containing the b3a2 bcr/abl cDNA . We also examined whether this model recreated the cellular phenotype of CML by assessing cell adhesion, cell migration, cell proliferation and cell survival . RESULTS: We found that significantly more myeloid colony forming units grew from p210BCR/ABL expressing cells, adhesion of p210BCR/ABL expressing CD34+ cells to fibronectin was decreased but migration over fibronectin was enhanced compared with mock transduced CD34+ cells . In this model, we showed that the presence of p210BCR/ABL leads to elevated levels of p27kip in p210BCR/ABL expressing CD34+ cells . We also showed that multidrug resistance-1 (MDR-1) Pgp was upregulated in the p210BCR/ABL expressing cells which correlates with the expression of p210BCR/ABL . CONCLUSION: This primary human CML model recreates most of the features of CML and provides a useful tool to study signal transduction and downstream molecular regulation drived by the p210BCR/ABL oncogene in normal CD34+ cells. Chin Med J (Engl), 2001 Jan, 114(1), 25 - 9 A bicistronic retroviral vector to introduce drug resistance genes into human umbilical cord blood CD34+ cells to improve combination chemotherapy tolerance; Wang J et al.; OBJECTIVE: To study whether human umbilical cord blood CD34+ cells transduced with human aldehyde dehydrogenase class-1 (ALDH-1) and multidrug resistance gene (MDR1) have increases resistance to 4-Hydroperoxycyclo-phosphamide (4-HC) and P-glycoprotein effluxed drugs . METHODS: A bicistronic retroviral vector G1Na-ALDH1-IRES-MDR1 was constructed and used to transfect the packaging cell lines GP + E86 and PA317 by LipofectAMINE method, using the medium containing VCR and 4-HC agents for cloning selection and ping-ponging supernatant infection between the ecotropic producer clone and the amphotropic producer clone, we obtained high titer amphotropic PA317 producing cells with high titers up to 5.6 x 10(5) CFU/ml . Cord blood CD34+ cells were transfected repeatedly with supernatant of retrovirus containing human ALDH-1 and MDR1cDNA under the stimulation of hemopoietic growth factors . RESULTS: Bicistronic retroviral vector construction was verified by restriction endonuclease analysis . Polymerase chain reaction (PCR), reverse transcription (RT)-PCR, Southern blot, Northern blot, fluorescenceactivated cell sorting (FACS) method and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) analyses showed that dual drug resistance genes have been integrated into the genomic DNA of cord blood CD34+ cells and expressed efficiently . The transgenes recipient cells confered 4-fold stronger resistance to 4-HC and 5.5 to 7.2-fold P-glycoprotein effluxed drug than untransduced cells . CONCLUSION: The bicistronic retroviral vector-mediated transfer of two different types of drug resistance genes into human cord blood CD34+ cells and co-expression provided an experimental foundation for improving combination chemotherapy tolerance in tumor clinical trial. Zhonghua Zhong Liu Za Zhi, 2000 Jul, 22(4), 304 - 7 {Expression of LRP, MRP and MDR1 in non-small-cell lung cancer and its clinical significance}; Wang J et al.; OBJECTIVE: To detect expression of lung resistance protein (LRP), multidrug resistance-associated protein(MRP) and multidrug resistance 1(MDR1) mRNA, and its clinical significance in non-small-cell lung cancer (NSCLC) . METHODS: RT-PCR was used to investigate mRNA expression of the above mentioned genes . RESULTS: The frequency of expression of LRP, MRP and MDR1 was 74.2%, 80.3% and 37.9%, respectively . A significant positive correlation was observed between LRP and MRP(r = 0.47, P = 0.001), but this association was found neither between LRP and MDR1, nor between MRP and MDR1 . The expression of LRP, MRP and MDR1 did not vary with the grade of cell differentiation and TNM staging . In adenocarcinomas which responded to chemotherapy, there was lowered expression of both LRP and MRP than those which did not respond . In chemo-responsive squamous-cell carcinomas, however, this was true of LRP expression only . The median survival time of NSCLC patients with co-expressed 2 and 3 drug resistance related genes was significantly reduced . CONCLUSION: The intrinsic multidrug resistance of NSCLC involves the combined effects of LRP, MRP and MDR1. Zhonghua Zhong Liu Za Zhi, 2000 Jul, 22(4), 273 - 5 {Establishment of MRP-overexpression subline of bladder carcinoma and its MDR phenotype}; Zhang X et al.; OBJECTIVE: To investigate MRP expression and multidrug resistance(MDR) phenotype of a bladder carcinoma subline transfected with the full length MRP cDNA . METHODS: After transfection, a stable MRP-overexpressed subline named EJ/MRP was established . Gene expression of MRP and mdr1 were detected by using RT-PCR and immunohistochemistry methods . Drug sensitivity testing of the EJ/MRP cells to 11 kinds of anti-cancer agents was examined . RESULTS: Compared with EJ/Vect which was mock transfected, MRP mRNA level of EJ/MRP increased 14.3 fold and MRP expression was mainly located in cytosol and plasma membrane . The relative resistance (RR) to VP-16, vincristine increased more than 10 fold, and that to doxorubicin, hydroxycamptothecin, thiotepa, mitomycin and cyclophosphamide increased 3 to 10 fold . CONCLUSION: Bladder carcinoma with stably over-expressed MRP presents typical MDR phenotype but without mdr1/P-gp expression . It provides a good model and positive control for the study of MRP-mediated MDR. Zhonghua Zhong Liu Za Zhi, 2000 Sep, 22(5), 385 - 8 {Development of drug resistance and alteration of cell cycle in lung cancer: a flow cytometric study}; Xu M et al.; OBJECTIVE: To study the relationship between the expression of multidrug resistance-associated protein (MRP) and P-glycoprotein (P-gp) and alteration of cell cycle during the process of drug resistance in lung cancer . METHODS: Lung adenocarcinoma cell line GLC-82 was treated with low concentration of adriamycin . At 0, 24, 48, 72 and 96 hr following adriamycin treatment, the expression of MRP and P-gp, and cell cycle were examined by bi-parameter flow cytometry . RESULTS: Treatment of GLC-82 cells with adriamycin at a final concentration of 0.05 microgram/ml resulted in progressive decrease in cells in G1 phase and increase in cells in S phase of the cell cycle . The expression level of P-gp was very low and showed little change with time . In contrast, MRP expression was significantly increased in a time-dependent manner, and was positively correlated with changes in S phase of the cell cycle . CONCLUSION: MRP expression may play a major role in the development of resistance to adriamycin. Zhonghua Zhong Liu Za Zhi, 2000 May, 22(3), 189 - 91 {Reversion of multidrug resistance in vitro of lung adenocarcinoma by mdr1 ribozyme}; Chen L et al.; OBJECTIVE: To investigate the possibility of reversion of multidrug resistant (MDR) in lung adenocarcinoma-resistant cell line A549/R by mdr1 ribozyme . METHODS: With GUC at 880 site of mdr1 mRNA selected as target point, plasmid expressing mdr1 ribozyme (pH beta Apr-1 neo/mdr1-Rb) was transduced to A549/R by lipofectin . The expression of mdr1 mRNA and Pgp, cellular rhodamine accumulation and sensitivity to doxorubicin were examined in ribozyme transduced and non-transduced cells . RESULTS: Transduction of mdr1 ribozyme to A549/R cells led to decrease in mdr1 mRNA and Pgp expression; increase in rhodamine accumulation . The sensitivity of the ribozyme transduced cells to doxorubicin was 200-fold as high as that of the parental drug-resistant cells . CONCLUSION: MDR of lung adenocarcinoma-resistant cell line A549/R can be effectively reversed with mdr1 ribozyme by cleavage of mdr1 mRNA and inhibition of Pgp expression. Zhonghua Zhong Liu Za Zhi, 2000 May, 22(3), 184 - 8 {Synthesis of chimeric anti-MDR1 ribozymes (tRNA-Rzs) and their biological activities in cell-free system}; Wang F et al.; OBJECTIVE: Development of multidrug resistance(MDR) is the major obstacle to successful cancer chemotherapy . One strategy to block the P-glycoprotein(P-gp)-mediated MDR is to use a ribozyme (Rz) target against MDR1 mRNA . METHODS: Three kinds of anti-MDR1 chimeric hammerhead ribozymes, the first-one cleaving codon 196 of MDR1 mRNA (196MDR1-Rz), the second one, a stem-II base modified (U9-->G9, U13-->A13, G14-->A14, A18-->C18) Rz against codon 196 (196MDR1-sRz) and the third one, the stem-II base modified Rz directed against the -6(-)-4 GUC sequence of the translation initiation site of the MDR1 mRNA (iMDR1-sRz), were synthesized based on the cloned retroviral constructs: N2A + tRNAi(met)-196MDR1-Rz, N2A + tRNAi(met)-196MDR1-sRz, N2A + tRNAi(met)-iMDR1-sRz . RESULTS: In a cell-free system, the chimeric tRNA-sRz molecules were more stable and had more efficient catalytic activities than the corresponding naked Rz molecules . The stem-II base modified Rz molecules were also more stable and efficient in catalytic activities than the unmodified ones . In control, the disabled tRNA-mut-iMDR1-sRz had no cleavage activity . CONCLUSION: Base modification in the Rz's stem-II of ribozyme structure and the development of chimeric tRNA-ribozyme molecules are able to enhance the cleavage efficacy. Exp Cell Res, 2002 Jan 15, 272(2), 185 - 91 Retinoic acid inhibits telomerase activity and downregulates expression but does not affect splicing of hTERT: correlation with cell growth rate inhibition in an in vitro cervical carcinogenesis/multidrug-resistance model; Ding Z et al.; Telomerase, a ribonucleoprotein complex of hTERT, hTR, and TP1, has been reported to be associated with carcinogenesis and multidrug resistance (MDR) . This study used our in vitro human cervical multistep carcinogenesis/MDR model system in which normal human ectocervical and endocervical (HEN) cells were immortalized by HPV18 or 16, respectively, and subsequently transformed . The first evidence was found that immortalization and telomerase activation were correlated with increased expression specifically of two of the hTERT alternatively spliced mRNAs, one encoding wild-type protein containing the full-length functional reverse transcriptase (RT) region and one encoding a defective RT protein . Expression of neither hTERT mRNA containing full-length functional or defective RT motif was affected by transformation/MDR . All-trans-retinoic acid (ATRA) treatment of HPV-immortalized HEN-16-2 cells and transformed/MDR HEN-16-2/CDDP cells inhibited telomerase activity and downregulated expression of hTERT mRNAs containing full-length functional and a defective RT motif, but there were no changes in hTR and TP1 expression . Moreover, ATRA inhibited cell growth rate of HEN-16-2 and HEN-16-2/CDDP cells equally . These results provided the first evidence that ATRA equally in both immortalized and transformed/MDR cell lines inhibits telomerase activity and downregulates expression, but not splicing, of hTERT, and this is correlated with cell growth rate inhibition; the potential is implicated for applying ATRA to hTERT-targeted treatment of cervical cell carcinogenesis/MDR . (c)2001 Elsevier Science. Zhonghua Kou Qiang Yi Xue Za Zhi, 1999 May, 34(3), 136 - 8 {Establishment and biological characteristics of vincristine: resistant cell line from human squamous cell carcinoma}; Zhang J et al.; OBJECTIVE: To establish a VCR-resistant cell line from human squamous cell carcinoma . METHODS: The cell line Tca8113 was utilized . The VCR concentration was increased gradually in consecutively passage of cultures . RESULTS: A VCR-resistant cell line Tca8113/V100 from Tca8113 was established, the cells grew steadily in 100 mumol/L medium and with 19.2 times of resistance to VCR . The cell line was also resistant to ADM, PYM, CDDP, MTX, 5-Fu at different degrees . The doubling time of the cells was 37.2 hours and showed microscopically and ultrastructurally typical squamous cell carcinoma when inoculated in nude mice . Blot hybridization showed the cells had increased espression of MDR-1mRNA . CONCLUSION: These results indicate that the cell line has multidrug resistant ability, and the reason for this may be over expression of MDR-1 gene . This cell line provides an important model for the study on drug-resistant cell both in cellular and molecular level, and on the mechanism of drug resistance. Zhonghua Zhong Liu Za Zhi, 1999 Mar, 21(2), 112 - 3 {Clinical significance of multidrug resistance-associated protein(MRP) gene expression in non-small cell lung cancer}; Zhan M et al.; OBJECTIVE: To investigate expression of multidrug resistance-associated protein (MRP) in non-small cell lung cancer and its relation to histological type, TNM staging and prognosis . METHODS: In situ hybridization was used to examine mRNA expression of MRP . RESULTS: The overall positive rate of MRP expression was 74.1%, with 73.3% and 72.0% in adenocarcinoma and squamous-cell carcinoma, respectively . The expression of MRP was not related to histological subtypes, TNM staging and cell differentiation . In 47 patients who received chemotherapy, 35 patients with positive MRP expression(+(-)++) showed worse prognosis than in those with negative expression (P < 0.05) . The median survival time was 8.7 months and 21 months in patients with positive and negative MRP expession, respectively . In patients with squamous-cell carcinoma, the survival rate was significantly lower in patients (n = 12) with positive MRP expression than in those (n = 7) with negative MRP expression (P < 0.05) . Their median survival time was 6 months and 19.5 months, respectively (P < 0.05) . CONCLUSION: The expression of MRP gene is negatively correlated with survival of patients with squamous-cell carcinoma, but not adenocarcinoma, who received chemotherapy. Zhonghua Zhong Liu Za Zhi, 1999 May, 21(3), 193 - 5 {Expression of multidrug resistance-associated protein (MRP) and lung resistance protein (LRP) in human rectal carcinomas and its clinical significance}; Peng X et al.; OBJECTIVE: To investigate the expression and clinical significance of multidrug resistance-associated protein(MRP) and lung resistance protein(LRP) in rectal carcinoma . METHODS: Fiftyseven paraffin embeded primary rectal carcinoma specimens were examined by immunohistochemical staining . RESULTS: Of the 57 tumour specimens examined, 28(49.1%) and 24(42.1%) were positively immunostaned for MRP and LRP, respectively . Co-expression of the two proteins was observed in 10(17.5%) specimens . Positive immunostaning of either of the two proteins was not correlated with cell differentiation and Dukes stage (P > 0.05) . Patients with MRP-positive tumours had shorter survival than MRP-negative patients (P < 0.05) . No such correlation was found for LRP expression, nor was found between MRP and LRP expression . CONCLUSION: Positive MRP expression in rectal carcinoma appears to be an independant factor of prognostic significance . To examine its expression may help guide rational comprehensive therapy of rectal carcinoma. Zhonghua Jie He He Hu Xi Za Zhi, 1999 Sep, 22(9), 562 - 3 {Cleaning cavity operation in treating relapse bacillary cavitary pulmonary tuberculosis}; Wei C et al.; OBJECTIVE: To study the effective surgical way for serious relapse multidrug resistant bacillary cavitary pulmonary tuberculosis . METHODS: 104 cases of serious relapse multidrug resistant bacillary cavitary pulmonary tuberculosis were cured by cleaning cavity operation from 1981 to 1998 . The operation contained resecting the back rib covering the cavity, separating the intercostal tissue, cutting the external wall of the cavity, cleaning the cavity thoroughly, scraping the cavity till exposing the fresh tissue, killing the tuberculosis germs with organic acid, filling the cavity with the intercostal muscle, fixing and suturing the muscles . RESULTS: Among the 104 cases, 103 cases (99.0%) were cured, 101 cases (98.1%) were cured after the first operation, one case (1.0%) became better . Among the 98 cases followed up, the rate of returning to work were 96%, no one died or relapsed . CONCLUSIONS: The design of cleaning cavity operation is reasonable and it is the effective method to treat the relapse bacillary cavitary pulmonary tuberculosis, the rate of cure and sputum conversion are promising. Zhonghua Jie He He Hu Xi Za Zhi, 1999 Sep, 22(9), 545 - 7 {The expression of MRP gene relates to the pathological features of lung cancer}; Wang Y et al.; OBJECTIVE: To evaluate the expression of MRP gene and its relation to pathological features in lung carcinoma . METHODS: A series of 35 resected primary lung cancer tissues from 9 post-chemotherapy and 26 untreated patients and adjacent normal lung tissues and 28 lymph node tissues were analyzed for MRP gene expression by RT-PCR method . RESULTS: Positive expression rate of MRP gene was 54% in 35 cases with primary lung cancer, 14% in tissues adjacent to the carcinoma site and the difference was significant (P < 0.005), the positive rate of MRP gene expression in metastatic lymph node tissues was 53% . In 9 cases of pre-operative chemotherapy, the positive expression rate of MRP gene was higher than that in 26 cases without chemotherapy . Nineteen of 35 tumors were found to show positive expression of MRP gene, comprising 11 of 18 adenocarcinoma, 9 of 15 squamous cell cancer . The relapse or metastasis rate with MRP-positive cases was higher(55%) than that with MRP-negative (15%) by follow-up of these patients . CONCLUSIONS: There are overexpression of MRP gene in primary lung cancer tissues . Preoperative chemotherapy may play inductive role in lung cancer multidrug resistance . The positive expression of MRP gene in lung cancer tissues is in accord with its lymph node tissues . Positive expression of MRP gene does not necessarily be associated with tumor size, clinical type and TNM stages, but it could be regarded as one poor prognostic factor. Zhonghua Zhong Liu Za Zhi, 2000 Jan, 22(1), 27 - 9 {Expression and prognostic significance of multidrug resistance associated protein (MRP) gene in non-small cell lung cancer by in situ hybridization}; Shan G et al.; OBJECTIVE: To study the effect of MRP gene overexpression on prognosis of patients with non-small cell lung cancer (NSCLC) . METHODS: Paraffin-embedded tissues from 47 cases of NSCLC who had undergone radical tumor resection were examined for expression of MRP gene mRNA by in situ hybridization using labelled digoxigenin probes combined with immunohistochemistry . All the patients were retrospectively followed-up . RESULTS: All of the 47 lung cancer specimens were found to have overexpression of MRP mRNA . It was significantly correlated with patients' survival period, response to chemotherapy, recurrence and mestastases after surgery, but was not correlated with histology, tumor size, node status, TNM stage, degree of differentiation, age and sex . CONCLUSION: Overexpression of MRP gene is a marker of prognostic significance in patients with NSCLC. Zhonghua Jie He He Hu Xi Za Zhi, 1999 Nov, 22(11), 655 - 8 {Expression of multidrug resistance-associated protein in human non-small cell lung cancer}; Peng X et al.; OBJECTIVE: To investigate the expression of the multidrug resistance-associated protein(MRP) gene and MRP in human non-small-cell lung cancer tissues and to determine whether such expression was related to cell type, differentiation, tumour size, lymph node metastasis and prognosis . METHODS: 92 paraffin-embeded lung tumor samples (43 squamous cell carcinoma, 49 adenocarcinoma) and 16 fresh non-small-cell lung cancer samples were examined by using immunohistochemistry method and the reverse transcription-polymerase chain reaction (RT-PCR) technology respectively . RESULTS: The expression of MRP mRNA and MRP were detectable in 31% (5-16) and 54% (50/92) of non-small-cell lung cancer specimens respectively . Eighteen(42%) squamous cell carcinoma specimens and thirty-two(65%) adenocarcinoma specimens showed positive immunostaining for MRP(P < 0.05) . The expression of MRP was not related to tumour size, lymph node metastasis and cell differentiation significantly(P > 0.05) . The five-year survival rate after operation of patients with MRP-positive tumours and MRP-negative tumours were 16% (8/50), 52% (22/42) respectively . Patients with MRP-positive tumours had shorter survival time than the MRP-negative patients significantly(P < 0.01) . CONCLUSIONS: Adenocarcinoma had higher MRP expression than squamous carcinoma significantly, positive MRP immunostaining appears to be an independent indicator of poor prognosis in NSCLC. Chin Med J (Engl), 2000 Nov, 113(11), 977 - 80 Upregulation of drug sensitivity of multidrug-resistant SGC7901/VCR human gastric cancer cells by bax gene transduction; Zhao Y et al.; OBJECTIVE: To investigate the role of bax in a vincristine (VCR)-induced multidrug-resistant (MDR) human gastric cancer cell line, SGC7901/VCR, in which the Bax protein expression level was significantly lower compared with that in parent cells . METHODS: A bax eukaryotic expression vector was constructed and transfected into SGC7901/VCR cells by lipofectamine, and resistant clones were selected by G418 . Western blotting detected Bax expression in transfectants . Tetrazolium blue (MTT) assay evaluated the differences in drug sensitivity and cell cycle changes of transfectants were analyzed using flowcytometry (FCM) . RESULTS: The bax eukaryotic expression vector was constructed and transfected into SGC7901/VCR cells . Through G418 selection, resistant clones were obtained . Western blotting demonstrated that the expression of Bax protein was markedly increased in bax transduced cells . These cells were more sensitive to adriamycin (ADR) and VCR than mock vector transducted cells . Moreover, bax transfection enhanced ADR-induced apoptosis and VCR-induced G2/M phase arrest of SGC7901/VCR cells . CONCLUSION: Bax was involved in the MDR of SGC7901/VCR cells. Chin Med J (Engl), 2000 Sep, 113(9), 848 - 51 The role of c-myc in regulating mdr1 gene expression in tumor cell line KB; He Y et al.; OBJECTIVE: To investigate the relationship between c-myc expression and mdr1 regulation in multidrug resistance (MDR) tumor cell line KBv200 . METHODS: A DNA sequence encoding the ribozyme gene was incorporated into a eukaryotic expression vector (pH beta Apr-1 neo) and transfected into the cell line KB, which is resistant to vincristine and expresses the MDR phenotype . The changes of c-myc protein, P-glycoprotein (P-gp) and c-myc mRNA in the KB cell line were assessed before and after treatment with anti-mdr1-ribozyme using immunohisto-chemistry, flow cytometry and semi-quantitative RT-PCR methods . RESULTS: The results demonstrate elevated levels of c-myc mRNA and c-myc protein as well as P-gp in KBv200 cells which are resistant to vincristine (VCR), compared to these of the KB cell which is not resistant to VCR . The expression of c-myc protein, P-gp and c-myc mRNA in the multidrug resistant cell, KBv200, displayed higher than that in the sensitive cell, KB . However, after reversing the multidrug resistance phenotype by anti-mdr1-ribozyme, the level of c-myc protein, P-gp and c-myc mRNA expression showed significant down-regulation in KBv/5 mR3, without difference in KB/5 mR3 and KB . CONCLUSION: The results of our study suggest that there is a close relationship between c-myc gene and mdr1 gene . c-myc may be involved in regulating the expression of mdr1. Chin Med J (Engl), 2000 Jun, 113(6), 536 - 9 {Chemoprotection of transfer of multidrug resistance gene into human hematopoietic progenitor cell}; Pan L et al.; OBJECTIVE: To observe the effect of the transfer of multidrug resistance gene (mdr1) into human hematopoietic progenitor cells (HPC) on the chemoprotection . METHODS: Human CD34+ cells served as a target of mdr1 gene transfer . Retroviral vector SF-mdr containing human total length mdr1cDNA was introduced into packing cells GP-envAM12 by liposome-mediated transfection . The mdr1 gene was transduced into human CD34+ cells by retroviral supernatants of packing cells . The integration and expression of the mdr1 gene and its protein (P170) in transduced cells were determined by PCR, RT-PCR, and flow cytometry . The drug resistance of chemotherapy in transduced HPC was determined by culturing colonies . RESULTS: The mdr1 gene was integrated and expressed in transduced CD34+ cells . The efficiency of mdr1 gene transfer was 10%-14% . Compared with untransduced controls, within a certain range of drug concentration, the number of drug-resistant colony in transduced HPC for taxol, doxorubicin, VCR and VP16 were increased by 3.6 +/- 2.1 fold, 2.9 +/- 0.3 fold, 1.9 +/- 0.4 fold, and 3.5 +/- 0.5 fold, respectively . CONCLUSION: The transfer of the mdr1 gene into human HPC can increase the drug resistance of the transduced cells to corresponding chemotherapeutic drugs that may provide some degree of chemoprotection for HPC. Zhonghua Jie He He Hu Xi Za Zhi, 1999 May, 22(5), 268 - 70 {Expression of multidrug resistance-associated protein gene in non-small cell lung cancer}; Xu M et al.; OBJECTIVE: To study the relationship between expression of multidrug resistance-associated protein (MRP) gene and occurrence of multidrug resistance (MDR) in non-small cell lung cancer (NSCLC) . METHODS: Thirty-two NSCLC samples were detected expression of MRP gene and chemosensitivity to 9 antitumor agents by RT-PCR, immunohistochemistry method and in vitro chemosensitivity assay . RESULTS: The positive expression rate of MRP mRNA in NSCLC was 72%, in lung tissue near carcinoma was 10%; the positive expression rate of MRP in NSCLC was 66%, positive staining of MRP located in membrane and cytoplasm of tumor cells, but no positive staining in lung tissue; MRP mRNA and MRP expression of moderate to high differentiation carcinoma was significantly higher than that of low differentiation carcinoma (P < 0.05) . There was significant correlation between expression of MRP mRNA and MRP in NSCLC . The expression of MRP in NSCLC, which was resistant to vincristine, etoposide and adriamycin, was higher than that being sensitive to these drugs (P < 0.05) . CONCLUSIONS: MRP gene may play an important role of intrinsic drug resistance in NSCLC, overexpression of MRP gene can be achieved through modulation at transcriptional and/or translation level . Overexpression of MRP is a major cause of resistance to vincristine, etoposide and adriamycin. Chin Med J (Engl), 2000 Oct, 113(10), 957 - 60 Co-transfection of MRP and bcl-2 antisense S-oligodeoxynucleotides reduces drug resistance in cisplatin-resistant lung cancer cells; Wang J et al.; OBJECTIVE: To detect the influence of antisense s-oligodeoxynucleotides (S-ODNs) of bd-2 and multidrug resistance-associated protein (MRP) genes multidrug resistance-associated protein gene and bcl-2 antisense S-oligodeoxynucleotides on cisplatin-resistant lung adenocarcinoma cell line A549DDP which overexpresses both bcl-2 and MRP . METHODS: A549DDP cells were treated with sense and antisense S-ODN mediated by lipofection . Expression of MRP and bcl-2 mRNA and protein in the treated cells was measured by RT-PCR and flow cytometry (FCM), respectively . Apoptosis was identified by DNA electrophoresis and terminal deoxynucleotidyl transferase (TdT)-mediated biotin dUTP nick end-labeling (TUNEL) . The degree of drug resistance of the treated cells was detected by a cell viability 3'-{4,5-dimethylthiazol-2-yl}-2, 5-diphenyl-tefrazolium bromide thiazolylblue (MTT) assay . RESULTS: Expression of bcl-2 and MRP significantly decreased in the cells treated with bcl-2 or/and MRP antisense S-ODN for 48 h as compared to the cells untreated and sense-treated (P < 0.05) . Resistance to cisplatin in the cells treated with bcl-2 or/and MRP antisense S-ODN decreased by 60.6% (6.5 times), 56.4% (7.2 times) and 71.0% (4.8 times), respectively, which paralleled the decrease of bcl-2 and MRP expression . Similarly, the resistance to etoposide and epirubicin in antisense-treated cells also reduced in parallel to decreases of the two gene expressions . The drug resistance in sense-treated cells was similar to that in untreated cells . Statistically significant dose- and concentration-dependent increases of apoptotic cells were observed in the groups exposed to 100 mumol/L cisplatin for 48 h after treatment by bcl-2 or/and MRP antisense . CONCLUSION: Bcl-2 and MRP were at least additive and possibly synergistic in conferring drug resistance in a cisplatin-resistant lung adenocarcinoma cell line . Antisense S-ODN could attenuate drug resistance by promoting cells apoptosis, which might lead to a new treatment for patients with non-small cell lung cancers (NSCLCs) who are refractory to conventional chemotherapy. Chin Med J (Engl), 2000 Mar, 113(3), 228 - 31 Expression of the human multidrug resistance gene mdr1 in leukemic cells and its application in studying P-glycoprotein antagonists; Fu J et al.; OBJECTIVE: To investigate the retrovirus-mediated transfer and expression of multidrug resistance gene (mdr1) in hematopoietic cells and to develop a model for studying the possible reversal of the MDR-mediated phenotype . METHODS: A retroviral vector HaMDR expressing the human mdr1 gene was packaged by PA317 cells with a titer of up to 8.5 x 10(5) CFU/ml . K562 leukemia cells were infected with MDR retrovirus, and transfectant K562/MDR cells were generated . The integration and expression of the exogenous mdr1 gene in K562/MDR cells were determined by polymerase chain reaction and flow cytometry . The reversal ability of P-glycoprotein (P-gp) antagonists was analyzed by in vitro drug sensitivity, accumulation and efflux of rhodamine 123 (Rh123) in this model . RESULTS: Transduction with amphotropic MDR retrovirus resulted in integration and expression of the mdr1 gene in the resistant cells, where an aberrant splicing transcript of the mdr1 gene was found . The K562/MDR cells displayed a classic MDR phenotype with a 41-78 fold resistance to vincristine and colchicine in comparison with parental K562 cells . The drug sensitivity of K562/MDR cells to vincristine can be completely restored by cyclosporin A (CsA, 2 mg/L) and Cremophor EL (CRE 132 mg/L), either individually or in combination (P < 0.05) . CsA (3 mg/L) can block the efflux pump function of P-gp shown by the significantly increased accumulation and efflux reduction of Rh123 in K562/MDR cells . CONCLUSIONS: Retroviral vector HaMDR allows transfection with high-level expression of the mdr1 gene in human myeloid progenitor cells K562 . The transfected K562/MDR provides a simple, sensitive model for developing antagonists of P-gp and studying their mechanism of action. Am J Gastroenterol, 2001 Dec, 96(12), 3368 - 78 The expression levels of plasma membrane transporters in the cholestatic liver of patients undergoing biliary drainage and their association with the impairment of biliary secretory function; Shoda J et al.; OBJECTIVES: Percutaneous transhepatic biliary drainage (PTBD) has been believed to reduce hyperbilirubinemia in patients with obstructive cholestasis and to lessen liver injury through bile acid retention . The efficacy may be closely related to the capability of cholestatic liver to produce and secrete bile, which in turn depends on the expressions and functional activities of plasma membrane transporters in the liver . The aim of the present study was to determine the expression levels of these transporters in the cholestatic liver of patients undergoing PTBD . METHODS: A total of 24 patients who had experienced obstructive cholestasis and had undergone preoperative PTBD were included in the study . Liver biopsy specimens were analyzed to determine the expression levels of the multidrug resistance-associated proteins (MRP) MRP2 and MRP3 and the canalicular bile salt export pump BSEP in the liver . RESULTS: The messenger RNA (mRNA) levels of MRP2, the canalicular bilirubin conjugate export pump, and bile salt export pump (BSEP) were unchanged in liver specimens from the 14 patients well drained by PTBD but were reduced in specimens from the 10 patients poorly drained, compared to the levels of control subjects . Immunostainings of MRP2 and BSEP outlined the canalicular membrane domain but seemed fuzzy to varying degrees in specimens obtained from cholestatic liver, especially in specimens from liver that had been poorly drained, in contrast to the linear and intense localization in the liver of control subjects, correlating with the impaired bilirubin conjugate and bile acid secretion . The mRNA of MRP3, functioning as an inducible export pump for bilirubin conjugate and bile acid, was expressed not only in the cholestatic liver but also in the liver of control subjects, and the mRNA level was increased in specimens from both the cholestatic liver that had been well drained and from the liver that had been poorly drained . Immunostaining of MRP3 was observed in the epithelia of intrahepatic bile ducts in the liver of both control subjects and cholestatic patients, and in the epithelia of proliferated bile ductules and the hepatocytes surrounding the portal tracts in the cholestatic liver . CONCLUSIONS: From the results of the present study, it is concluded that 1) the mRNA and immunohistochemical expression levels of MRP2 and BSEP may be altered in the cholestatic liver of patients undergoing PTBD; 2) both the decreased mRNA levels and the diminished canalicular membrane localization may be associated with the impairment of bile formation and secretion, i.e., the efficacy of PTBD; and 3) upregulated MRP3 in the cholangiocytes and hepatocytes may play a significant role in bile acid transport in the cholestatic hepatobiliary system. Hum Cell, 2001 Sep, 14(3), 172 - 84 Novel approaches to reversing anti-cancer drug resistance using gene-specific therapeutics; Kobayashi H et al.; One of the underlying mechanisms of multidrug resistance (MDR) is cellular overproduction of P-glycoprotein (P-gp), which acts as an efflux pump for various anti-cancer drugs . P-gp is encoded by a group of related genes termed MDR; only MDR1 is known to confer the drug resistance, and its overexpression in cancer cells has been a therapeutic target to circumvent the resistance . To overcome P-gp-mediated drug resistance, we have developed six anti-MDR1 hammerhead ribozymes and delivered them to P-gp-overproducing human leukemia cell line by a retroviral vector containing RNA polymerase III promoter . These ribozyme-transduced cells became vincristine-sensitive, concomitant with the decreases in MDR1 expression, P-gp amount and efflux pump function . Among the ribozymes tested, the anti-MDR1 ribozyme against the translation-initiation site exhibited the highest efficacy . The retrovirus-mediated transfer of this most potent anti-MDR1 ribozyme into a human lymphoma cell line, which was made resistant by infection of pHaMDR1/A retroviral vector and thus possessed a low degree of MDR due to P-gp expression relevant to clinical MDR, resulted in a complete reversal of MDR phenotype . In addition to retrovirus-mediated transfer of ribozymes, we evaluated the efficacy of cationic liposome-mediated transfer of ribozyme . Treatment of a P-gp-producing human breast cancer cell line with the liposome-ribozyme complex resulted in reversal of resistance, concomitant with the decreases in both MDR1 expression and P-gp amount . Confocal microscopic imaging of the cells after treatment with liposome/FITC-dextran showed cytoplasmic fluorescence that was abolished by cytochalasin B, indicating a high endocytotic activity in these cells . The endocytotic activity was well correlated with the success of cationic liposome-mediated transfer of MDR1 ribozyme . These distinct approaches using either retrovirus- or liposome-mediated transfer of anti-MDR1 ribozyme may be selectively applicable to the treatment of MDR cells with different properties such as endocytotic activity as a specific means to reverse resistance. Zhonghua Kou Qiang Yi Xue Za Zhi, 1998 May, 33(3), 137 - 9 {The correlation between P-glycoprotein and multidrug resistance of squamous carcinoma in oral and maxillofacial region}; Xie Z et al.; OBJECTIVE: To study the mechanism of drug resistance of oral carcinoma to chemotherapy . METHODS: 40 cases of squamous carcinoma in the oral and maxillofacial region were examined for the multidrug resistance gene product P-glycoprotein using a monoclonal antibody MRK16 . RESULTS: P-glycoprotein was detected in 62.5% of the sample . P-glycoprotein expression was related to the chemotherapy and the degree of differentiation . P-glycoprotein expression was higher in post-chemotherapy group than in unchemotherapy group (P < 0.05) . Well differentiated tumors expressed P-glycoprotein more frequently (P < 0.05) . P-glycoprotein expression was compared with clinic response to chemotherapy . The accuracy rate of prediction is 75% . CONCLUSION: P-glycoprotein plays an important role in mechanism of multidrug resistance of squamous carcinoma in the oral and maxillofacial region. Int J Cancer, 2002 Jan 20, 97(3), 278 - 82 Y-box factor YB-1 predicts drug resistance and patient outcome in breast cancer independent of clinically relevant tumor biologic factors HER2, uPA and PAI-1; Janz M et al.; Intrinsic or acquired resistance to chemotherapy is responsible for failure of current treatment regimens in breast cancer patients . The Y-box protein YB-1 regulates expression of the P-glycoprotein gene mdr1, which plays a major role in the development of a multidrug-resistant tumor phenotype . In human breast cancer, overexpression and nuclear localization of YB-1 is associated with upregulation of P-glycoprotein . In our pilot study, we analyzed the clinical relevance of YB-1 expression in breast cancer (n = 83) after a median follow-up of 61 months and compared it with tumor-biologic factors already used for clinical risk-group discrimination, i.e., HER2, urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor type 1 (PAI-1) . High YB-1 expression in tumor tissue and surrounding benign breast epithelial cells was significantly associated with poor patient outcome . In patients who received postoperative chemotherapy, the 5-year relapse rate was 66% in patients with high YB-1 expression . In contrast, in patients with low YB-1 expressions, no relapse has been observed so far . YB-1 expression thus indicates clinical drug resistance in breast cancer . Moreover, YB-1 correlates with breast cancer aggressiveness: in patients not treated with postoperative chemotherapy, those with low YB-1 expression are still free of disease, whereas the 5-year relapse rate in those with high YB-1 was 30% . There was no significant correlation between YB-1 expression and either HER2 expression or uPA and PAI-1 levels . Risk-group assessment achieved by YB-1 differed significantly from that by HER2 or uPA/PAI-1 . In conclusion, YB-1 demonstrated prognostic and predictive significance in breast cancer by identifying high-risk patients in both the presence and absence of postoperative chemotherapy, independent of tumor-biologic factors currently available for clinical decision making . Int J Cancer, 2002 Jan 10, 97(2), 149 - 56 A very early induction of major vault protein accompanied by increased drug resistance in U-937 cells; Hu Y et al.; U-937 human leukemia cells were selected for resistance to doxorubicin in the presence or absence of a specific drug modulator that inhibits the activity of P-glycoprotein (Pgp), encoded by the multidrug-resistance gene (MDR1) . Parental cells expressed low basal levels of the multidrug-resistance-associated gene (MRP1) and major vault protein (MVP) mRNAs and no MDR1 mRNA . Two doxorubicin-resistant cell lines were selected . Both drug-resistant cell lines upregulated the MVP mRNA level 1.5-fold within 1 cell passage . The MVP mRNA level continued to increase over time as the doxorubicin selection pressure was increased . MVP protein levels generally paralleled the mRNA levels . The 2 high molecular weight vault protein mRNAs were always expressed at constitutive levels . Fully formed vault particles consisting of the MVP, the 2 high molecular weight proteins and the vault RNA assembled and accumulated to increased levels in drug-selected cells . MVP induction is therefore the rate-limiting step for vault particle formation in U-937 cells . By passage 25 and thereafter, the selected cells were resistant to doxorubicin, etoposide, mitoxantrone and 5-fluorouracil by a pathway that was independent of MDR1, MRP1, MRP2 and breast cancer resistance protein . In summary, U-937 doxorubicin-selected cells are programmed to rapidly upregulate MVP mRNA levels, to accumulate vault particles and to become multidrug resistant . Int J Cancer, 2002 Jan 1, 97(1), 21 - 7 Expression of heavy subunit of gamma-glutamylcysteine synthetase (gamma-GCSh) in human colorectal carcinoma; Tatebe S et al.; Gamma-glutamylcysteine synthetase (gamma-GCS) is a heterodimer consisting of heavy (gamma-GCSh) and light (gamma-GCSl) subunits . gamma-GCS catalyzes the rate-limiting de novo biosynthesis of glutathione (GSH), an abundant physiological antioxidant that plays important roles for regulating oxidative stress . Expression of gamma-GCSh and gamma-GCSl are sensitive to oxidative stress . To investigate whether expression of gamma-GCS is correlated with tumor progression, we used immunohistochemical approaches to examine 16 human colorectal adenomas and resected 57 carcinomas from untreated patients . In adjacent normal colorectal epithelium, levels of gamma-GCSh expression were low . Strong cytoplasmic staining for gamma-GCSh was detected in 3 (18.8%) adenoma and 48 (84.2%) carcinomas . The frequency of gamma-GCSh expression in carcinoma was significantly higher than in adenoma (p<0.0001) . We used RNase protation assay and Western blot to determine levels of gamma-GCSh mRNA and protein from 10 pairs of matched carcinomas with adjacent normal controls . Elevated expression of both gamma-GCSh mRNA and protein were found in 6 cases, suggesting that transcriptional and/or posttranscriptional regulation play an important role in the upregulation of gamma-GCS during colorectal carcinogenesis . We also examined the expression of another redox-regulated gene, multidrug resistance protein 1 (MRP1) . Strong staining for MRP1 was detected in 1 (6.3%) adenoma and 40 (70.2%) carcinomas . The frequency of MRP1 expression in carcinoma was significantly higher than in adenoma ( p<0.0001) . Nuclear p53 expression was detected in 30 (52.6%) of carcinomas . There is a significant correlation between gamma-GCSh and MRP1 expression (p=0.013) but not between gamma-GCSh and p53 . Since gamma-GCS is a sensor of oxidative stress, these results are consistent with the notion that oxidative stress is associated with colorectal tumor progression . Clin Infect Dis, 2002 Feb 1, 34(3), 324 - 9 Epub 2001 Dec 26. Trends in multidrug-resistant Mycobacterium tuberculosis in relation to sputum smear positivity in Hong Kong, 1989-1999; Kam KM et al.; We studied retrospectively the territory-wide occurrence and trends of multidrug-resistant tuberculosis (MDR-TB) in Hong Kong over an 11-year period during which a short-course directly observed therapy ("DOTS-Plus") strategy has been in operation . The overall MDR rate was 2.1% (primary, 1.4% and acquired, 9.5%) and declined at 0.08% per year: smear-positive primary MDR cases declined at yearly rate of -0.065% (R2=.23), and smear-negative primary MDR cases increased at 0.035% yearly . With declining rates of smear positivity, sputum culture has become the mainstay of detection of MDR-TB . Although the overall notification rates showed the elderly (age >65 years) age group to be most affected, the occurrence of MDR-TB has been consistently highest in the 35-65 year age group (60.4% of MDR caseload) . We demonstrated declining rates of sputum smear positivity of MDR-TB in a DOTS-plus environment and that a centralized laboratory database is essential in gathering epidemiological information for identifying particular risk groups and monitoring trends of MDR-TB in a community. J Control Release, 2002 Jan 17, 78(1-3), 43 - 54 Role of transporters in the tissue-selective distribution and elimination of drugs: transporters in the liver, small intestine, brain and kidney; Kusuhara H et al.; Cumulative studies have revealed the importance of transporters in drug disposition in the body . Recently, organic anion transporters such as organic anion transporting polypeptides (OATPs), organic anion transporters (OATs) and multidrug resistance associated proteins (MRPs) have been identified . Their broad substrate specificity as well as the multiplicity of transporter gene products make these transporters suitable detoxification systems in the body . OATPs and OATs are responsible for the hepatic and renal uptake of organic anions, respectively, while MRP2 is a major transporter involved in the biliary excretion of organic anions . OATPs and MRP2 are involved in the hepatobiliary transport of pravastatin and temocaprilat . These are good examples of hepatobiliary transport maximizing their pharmacological effects, but minimizing their side-effects . Taking into consideration tissue-selective expression and substrate specificity, transporters are useful for delivering small molecules to target tissues . MRPs are also suggested to be involved in the barrier function in the small intestine, blood-brain barrier and blood-cerebrospinal fluid barriers by extruding their ligands into the luminal side . In this manuscript, we have summarized recent studies by others and ourselves on the role of these transporters in the tissue selective distribution and elimination of drugs. Curr Pharm Des, 2001 Dec, 7(18), 1863 - 92 Radiolabelled tracers and anticancer drugs for assessment of therapeutic efficacy using PET; Brady F et al.; Positron Emission Tomography (PET) has the potential to improve efficacy of established and novel cancer therapies and to assist more rapid and rational progression of promising novel therapies into the clinic . This is due to PET's unrivalled sensitivity and ability to monitor the pharmacokinetics and pharmacodynamics of drugs and biochemicals radiolabelled with short -lived positron emitting radioisotopes . PET is a multidisciplinary science which employs chemists, biologists, mathematical modellers, pharmacologists as well as clinicians . Clinical research questions in oncology determine the methodological challenges faced by these other disciplines . Within this context we focus on the developments of the radiolabelled compounds that have underpinned the clinical work in oncology for monitoring tumour and normal tissue pharmacokinetics, assessment of tumour response, cell proliferation, gene expression, hypoxia, multidrug resistance and status of receptors on tumours. Int J Tuberc Lung Dis, 2001 Dec, 5(12), 1137 - 42 Directly observed treatment for multidrug-resistant tuberculosis: an economic evaluation in the United States of America and South Africa; Wilton P et al.; OBJECTIVE: To estimate the cost-effectiveness of directly observed treatment compared to conventional therapy in reducing the spread of multidrug-resistant tuberculosis, for an industrialised country (represented by the United States of America) and a developing country (South Africa) . METHODS: Monte Carlo analysis using published data on probability, cost and health impact . RESULTS: In both countries, directly observed treatment is the dominant strategy, yielding cost savings and improved health outcomes . Cost savings for directly observed treatment relative to conventional therapy become more significant as more expensive second-line drugs are used in treatments . CONCLUSIONS: The cost-effectiveness of directly observed treatment relative to conventional therapy is demonstrated for both the USA and South Africa . Cost savings are more pronounced (especially for South Africa) as the likelihood of multidrug-resistant tuberculosis increases and more expensive second-line therapies are used . Given that health care resources are more severely constrained in developing countries, the data contained in this study are useful in guiding the design of policies for the effective management of multidrug-resistant tuberculosis in settings with limited resources. Int J Tuberc Lung Dis, 2001 Dec, 5(12), 1129 - 36 Ambulatory treatment of multidrug-resistant pulmonary tuberculosis patients at a chest clinic; Kim HJ et al.; SETTING: Retrospective cohort analysis of multidrug-resistant tuberculosis (MDR-TB) patients treated at a Korean National Tuberculosis Association out-patient chest clinic . OBJECTIVE: To evaluate treatment outcomes and contributing factors . DESIGN: A review of clinical records of 1011 pulmonary MDR-TB patients retreated with individualised regimens selected on the basis of previous chemotherapy and drug susceptibility testing from 1988 to 1996 . RESULTS: The patients (mean age 38.6 years) had resistant organisms to an average of 3.7 drugs and were retreated with an average of 4.2 drugs which they had previously not taken and to which they were susceptible . Treatment outcomes were as follows: 487 cases (48.2%) cured, 82 (8.1%) failed, 394 (39.0%) defaulted, 45 (4.5%) transferred out, and three (0.3%) died . The treatment efficacy among those who completed chemotherapy was 85.6% . In a multivariate analysis favourable response was significantly associated with a greater number of newly prescribed drugs in the regimen to which they were susceptible (odds ratio {OR} 3.6; 95% confidence interval {CI} 1.3-9.5), younger age (OR 2.0; 95%CI 1.1-3.9), and a lower number of drugs to which they were resistant (OR 1.8; 95%CI 1.1-3.1) . The case fatality rate, including the follow-up period, was 1.7% (17 cases) . CONCLUSION: The cure rate of MDR-TB patients treated at an out-patient clinic was 48.2% due to a high defaulter rate (39.0%) . However, 85.6% of those who completed treatment were cured. Int J Tuberc Lung Dis, 2001 Dec, 5(12), 1116 - 21 Pattern of mycobacterial resistance to four anti-tuberculosis drugs in pulmonary tuberculosis patients in the state of Qatar after the implementation of DOTS and a limited expatriate screening programme; Al-Marri MR; OBJECTIVE: To determine the resistance pattern of Mycobacterium tuberculosis to four anti-tuberculosis drugs in pulmonary tuberculosis patients in the State of Qatar after the implementation of DOTS and an expatriate screening programme on arrival . METHOD: A state-wide, population-based, retrospective analysis of all cases of pulmonary tuberculosis with positive M . tuberculosis culture reported to the Division of Public Health TB Unit from January 1996 to December 1998 . M . tuberculosis sensitivity testing was done by the Bactec method for isoniazid (INH), rifampicin (RMP), streptomycin (SM) and ethambutol (EMB) . The results were interpreted as a daily change of the growth index of test vials (with drug) compared with controls . RESULTS: There were 406 isolates with positive M . tuberculosis culture . Sixty-one (15%) were resistant to one or more of the four anti-tuberculosis drugs, of which 58 (95%) were from newly diagnosed cases (primary) and three (5%) were from previously treated cases (acquired) . Primary resistance was as follows: any resistance 15%, INH 12.4%, RMP 2%, SM 5.2%, EMB 0.8% and multidrug resistance (MDR, resistance to INH and RMP at least) was found in 0.8% . Acquired resistance was as follows: any resistance 15%, INH 15%, RMP 5%, SM 5% and MDR 5% . CONCLUSION: The prevalence of resistance to four anti-tuberculosis drugs is strikingly low due to the limited expatriate screening programme (chest radiography) and implementation of DOTS . The four-drug regimen is recommended for the initial phase of therapy until the results of sensitivity testing are known. Zhonghua Fu Chan Ke Za Zhi, 2001 Sep, 36(9), 549 - 53 {Establishment of the drug resistant cell line of choriocarcinoma and the reversal of drug resistance by transfection of human interleukin 2 gene}; Cui Z et al.; OBJECTIVE: To establish the drug-resistant cell line of choriocarcinoma and to study the transfection of the human interleukin 2 (hIL-2) gene into the established drug resistant cell line and investigate the reversal of the multidrug resistance . METHODS: The resistant cell line was established by pulse exposed choriocarcinoma cell line JEG-3 to etopside (VP-16) for ten months . The recombinant plasmid containing pcDNA3.1(+)-hIL-2 gene was constructed . The drug resistant cell line was transfected with the constructed plasmid by lipofectin, and the tumor cell colonies containing the IL-2 sequence were selected by genetin . The expression of hIL-2 and drug resistant-related genes was detected by reverse transcript polymerase chain reaction . The chemosensitivity of the gene-transfected tumor cells and the non transfected cell lines to methetraxate, VP-16, kengshengmycine, paclitaxol and 5-fluorouracil was determined by the methyl thiazolyl tetrazolium cytotoxicity assay . RESULTS: The transfected cells expressed human hIL-2 gene, and showed the reversal of multidrug resistance by methyl thiazolyl tetrazolium assay . The transfected cells expressed no multidrug resistance gene-1 (MDR1) on mRNA level . Drug resistance index to VP-16 decreased from 38.7 to 6.0 and 6.1, the index to methetraxate decreased from 14.5 to 2.6 and 2.5, to methetraxate from 13.0 to 2.0 . CONCLUSION: The transfection of hIL-2 gene into the drug resistance cell line of choriocarcinoma can modulate the MDR1 expression on the mRNA level, and reverse the drug resistance. Drug Resist Updat, 2001 Jun, 4(3), 187 - 96 Drug resistant falciparum malaria: clinical consequences and strategies for prevention; Price RN et al.; The rising prevalence of multidrug resistant falciparum malaria is occurring at an alarming rate and has serious implications for the health of many of the world's poorest countries . The dangers of not changing treatment practices immediately are huge and irreversible, threatening to both exacerbate the scale and scope of the malaria pandemic, and deprive policymakers of future options against the disease . If a health care disaster is to be avoided then massive and long term funding is urgently required . Funds need to be applied in a cohesive manner, accountable to funding bodies and tailored to the specifics of each endemic region . The key elements of such an approach should be improving early diagnosis and treatment of infection and the deployment of combination regimens containing an artemisinin derivative.These short term measures will need to be accompanied by a longer term strategy to encourage antimalarial drug research and development. Curr Drug Metab, 2001 Dec, 2(4), 367 - 77 The MRP family and anticancer drug metabolism; Suzuki T et al.; Acquirement of drug resistance by tumor cells is a major chemotherapeutic problem . It is well known that typical multidrug resistance is caused by P-glycoprotein and multidrug resistance related protein (MRP1) which belong to the ATP binding cassette (ABC) transporter family . Ishikawa proposed that the ATP-dependent glutathione-S-conjugate export pump (GS-X pump) and phase III detoxification system are essential to drug metabolism, and this constituted a new concept in drug metabolism and the detoxification of xenobiotics . The GS-X pump has been revealed to belong to the ABC transporter family and suggested to the contribution to anticancer drug resistance . The GS-X pump actively effluxes the glutathione S-platinum (GS-Pt) complex . We cloned novel ABC transporter cDNA from the PC-14/CDDP cell line, and the cloned cDNA was designated as a short-type MRP homologue, SMRP . Further investigation suggested that SMRP