Am J Trop Med Hyg, 1998 Jan, 58(1), 11 - 6 Comparative clinical trial of artesunate suppositories and oral artesunate in combination with mefloquine in the treatment of children with acute falciparum malaria; Sabchareon A et al.; A randomized pilot study to compare the safety and efficacy of artesunate suppositories (15 mg/kg/day for three days) versus oral artesunate (6 mg/kg/day for three days), both in combination with mefloquine (25 mg/kg), was conducted in 52 Thai children with uncomplicated multidrug-resistant falciparum malaria . Forty-five patients (87%) had a full 28-day follow-up in the hospital to assess efficacy and exclude reinfection . Mean {range} times to fever clearance of the two groups were similar (42 hr {15-104} versus 42 hr {6-119}) . Artesunate suppositories resulted in significantly longer times to achieve 50% and 90% reductions of the initial parasite counts (17 and 26 hr versus 9 and 15 hr; P < 0.05 and P < 0.001) . Time {range} to parasite clearance was longer in the artesunate suppositories group (42 hr {14-93} versus 35 hr {16-69}), but the difference was not significant . The cure rates by days 28 were not significantly different, 92% for artesunate suppository-treated patients and 100% for oral artesunate-treated patients . Both drug regimens are safe and effective . Further studies are needed to characterize the pharmacokinetic properties and the optimum regimen of artesunate suppositories for the treatment of severe malaria. Br J Haematol, 1998 Jan, 100(1), 194 - 7 Functional multidrug resistance in acute myeloblastic leukaemia: a standardized flow cytometric assay for intracellular daunorubicin accumulation; Pallis M et al.; We have developed a standardized flow cytometric method for the measurement of in vitro multidrug resistance in acute myeloblastic leukaemia (AML) blasts, using carboxylate microspheres which bind the fluorescent drug daunorubicin . Cells and beads were incubated concurrently with the drug . Fluorescence was expressed as a cell:bead ratio . Bead fluorescence at a fixed cytometer voltage was consistent over at least a 3-month period (CV 5.47%), and repeat assays up to 8 months later correlated well (R = 0.86) . Bead to drug binding provides a valuable measure of quality assurance as well as a standard for cellular drug accumulation assays and would therefore be suitable for reproducibly reporting the results of multidrug resistance analysis in a clinical setting. J Chromatogr B Biomed Sci Appl, 1997 Nov 21, 702(1-2), 203 - 10 High-performance liquid chromatographic determination of pyrazoloacridine, a nitro-9-methoxyacridine anticancer agent, in human plasma; Jayewardene AL et al.; Pyrazoloacridine (PZA) is a 9-methoxy substituted acridine with a reducible nitro group . PZA has shown selective solid tumor cytotoxicity with activity against hypoxic cells, non-cycling cells and cells expressing the multidrug resistant phenotype . A high-performance liquid chromatographic (HPLC) assay was developed and validated for the determination of PZA in human plasma to support phase II clinical trials . PZA and ethyl orange, the internal standard, were isolated from human plasma by precipitating plasma proteins with methanol, and centrifuging to pellet the proteins . The resulting supernatant was injected onto a cyanopropyl HPLC column eluted isocratically with a mobile phase consisting of 125 mM ammonium acetate buffer pH 4.75-acetonitrile (76:24, v/v) . A single wavelength at 460 nm was used for detection . Relative standard deviations for the assay ranged from 5.0% to 12.2% for four different drug concentrations and the limit of quantitation was 100 ng/ml . During the validation short term stability of the drug in plasma and stability of PZA on repeated freezing and thawing of plasma was evaluated . Overall recovery of PZA was 88% . This simple assay was found suitable for studying the clinical pharmacokinetics of PZA. J Chromatogr B Biomed Sci Appl, 1997 Nov 21, 702(1-2), 181 - 91 On the use of ion-pair chromatography to elucidate doxorubicin release mechanism from polyalkylcyanoacrylate nanoparticles at the cellular level; Pepin X et al.; The major hypothesis underlying the remarkable efficiency of polyalkylcyanoacrylate particles loaded with doxorubicin against multidrug resistant tumor cells in vitro, is based on the ion-pair association of doxorubicin with soluble hydrolysis products of polyalkylcyanoacrylate . In an attempt to demonstrate the validity of this hypothesis, we have used ion-pair reversed-phase high-performance liquid chromatography and a laboratory-synthetized compound, i.e., the 2-cyano-2-butylhexanoic acid, as a model for polyalkylcyanoacrylate highly polydispersed degradation products . It is shown that, compared to a counter-ion, like heptane sulfonic acid, 2-cyano-2-butylhexanoic acid exhibits an effective ion-pairing effect at different pH values and organic mobile phase conditions . Moreover, at pH close to physiological conditions and at low mobile phase organic modifier percentage, this effect is experimentally observed, which strongly supports the initial hypothesis. Antimicrob Agents Chemother, 1998 Jan, 42(1), 135 - 9 Randomized comparison of artemether-benflumetol and artesunate-mefloquine in treatment of multidrug-resistant falciparum malaria; van Vugt M et al.; An open, randomized comparison of artemether-benflumetol (CGP 56 697; Novartis) with artesunate-mefloquine was conducted in 617 patients with acute uncomplicated multidrug-resistant falciparum malaria on the western border of Thailand . Both treatments rapidly and reliably cleared fever and parasitemia, and there was no significant difference in the initial therapeutic response parameters . Parasite genotyping was used to distinguish recrudescences from new infections . The 63-day cure rate for artesunate-mefloquine (94%) was significantly higher than the cure rate for artemether-benflumetol (81%) (P < 0.001) . Both regimens were well tolerated . Nausea, vomiting, dizziness, sleep disorders, and other neurological side effects were between two and four times more common in the artesunate-mefloquine group than in the artemether-benflumetol group (P < 0.001) . Artemether-benflumetol is effective and very well tolerated in the treatment of multidrug-resistant falciparum malaria . A higher dose than that used in the present study may improve efficacy. Antimicrob Agents Chemother, 1998 Jan, 42(1), 88 - 93 Characterization of mutations contributing to sulfathiazole resistance in Escherichia coli; Vedantam G et al.; A sulfathiazole-resistant dihydropteroate synthase (DHPS) present in two different laboratory strains of Escherichia coli repeatedly selected for sulfathiazole resistance was mapped to folP by P1 transduction . The folP mutation in each of the strains was shown to be identical by nucleotide sequence analysis . A single C-->T transition resulted in a Pro-->Ser substitution at amino acid position 64 . Replacement of the mutant folP alleles with wild-type folP significantly reduced the level of resistance to sulfathiazole but did not abolish it, indicating the presence of an additional mutation(s) that contributes to sulfathiazole resistance in the two strains . Transfer of the mutant folP allele to a wild-type background resulted in a strain with only a low level of resistance to sulfathiazole, suggesting that the presence of the resistant DHPS was not in itself sufficient to account for the overall sulfathiazole resistance in these strains of E . coli . Additional characterization of an amplified secondary resistance determinant, sur, present in one of the strains, identified it as the previously identified bicyclomycin resistance determinant bcr, a member of a family of membrane-bound multidrug resistance antiporters . An additional mutation contributing to sulfathiazole resistance, sux, has also been identified and has been shown to affect the histidine response to adenine sensitivity displayed by these purU strains. Biochem Pharmacol, 1998 Jan 15, 55(2), 131 - 9 Altered drug membrane permeability in a multidrug-resistant Leishmania tropica line; Chiquero MJ et al.; We selected a Leishmania tropica cell line resistant to daunomycin (DNM) that presents a multidrug-resistant (MDR) phenotype characterized by overexpression of a P-glycoprotein of 150 kDa . The resistant line overexpressed an MDR-like gene, called ltrmdr1, located in an extrachromosomal circular DNA . DNM uptake experiments using laser flow cytometry showed a significant reduction in drug accumulation in the resistant parasites . The initial stages of the interaction of DNM with membranes from wild-type and DNM-resistant parasites were defined by a rapid kinetic stopped-flow procedure which can be described by two kinetic components . On the basis of a previous similar kinetic study with tumor cells, we ascribed the fast component to rapid interaction of DNM with membrane surface components and the slow component to passive diffusion of the drug across the membranes . The results reported here indicate that entrance of DNM into wild-type parasites was facilitated in respect to the resistant ones . We propose that resistance to DNM in L . tropica is a multifactorial event involving at least two complementary mechanisms . an altered drug membrane permeability and the overexpression of a protein related to P-glycoprotein that regulates drug efflux. Biol Pharm Bull, 1997 Dec, 20(12), 1303 - 6 Potentiation of pirarubicin activity in multidrug resistant cells by rifampicin; Furusawa S et al.; The effect of the anti-tuberculosis drug rifampicin on pirarubicin activity was investigated in multidrug-resistant cells overexpressing P-glycoprotein . Rifampicin increased the sensitivity of pirarubicin to anthracycline-resistant mouse leukemic P388 cells and significantly enhanced the cytotoxicity and intracellular accumulation of pirarubicin in resistant cells, but had no effect in parent cells . By contrast, two other rifamycins, rifamycin B and SV, had no effect on pirarubicin accumulation in resistant cells . Rifampicin also enhanced pirarubicin-induced apoptosis and G2/M blockade on the cell cycle in resistant cells . These results show that rifampicin enhances the cytotoxic action of pirarubicin in resistant cells, at least partly via the inhibition of cellular pirarubicin efflux. Biol Pharm Bull, 1997 Dec, 20(12), 1257 - 60 Anti-proliferative effect of toremifene and tamoxifen on estrogen receptor-lacking anaplastic thyroid carcinoma cell lines; Kishino T et al.; The antitumor effects of toremifene were studied in vitro using 10 anaplastic thyroid carcinoma cell lines and were compared with those of tamoxifen . The antitumor effect of toremifene was dose-dependent and the IC50 values for these cell lines ranged 20.1-58.5 microM . Although the cell lines expressed multidrug resistance gene mRNA, multidrug resistance-associated protein gene mRNA and insulin-like growth factor-1 (IGF-1) receptor mRNA to various degrees, nine of them lacked estrogen receptor expression as evaluated by immunocytochemistry . These data indicate that toremifene, as well as tamoxifen, is cytolytic at relatively high doses for multidrug-resistant anaplastic thyroid carcinoma cell lines. Bull World Health Organ, 1997, 75(5), 477 - 89 Practical and affordable measures for the protection of health care workers from tuberculosis in low-income countries; Harries AD et al.; With the global upsurge in tuberculosis (TB), fueled by the human immunodeficiency virus (HIV) pandemic, and the increase in multidrug-resistant TB, the condition has become a serious occupational hazard for health care workers worldwide . Much of the current understanding about nosocomial TB transmission stems from the USA; however, little is known about the risk of such transmission in low-income countries . The focus of this review is on sub-Saharan Africa, since this is the region with the highest TB incidence, the highest HIV incidence, the worst epidemic of HIV-related TB, and where the risk to health care workers is probably greatest . Measures used in industralized countries to control nosocomial TB transmission (ventilation systems, isolation rooms, personal protective equipment) are beyond the resources of low-income countries . Protecting health care workers in these settings involves practical measures relating to diagnosis and treatment of infectious cases; appropriate environmental control; and relevant personal protection and surveillance of health care workers . Research needs to be carried out to examine the feasibility and cost-effectiveness of measures such as voluntary HIV-testing of health care workers (to enable known HIV-positive health care workers to avoid high-risk settings) and isoniazid preventive therapy for workers in high-risk settings . More resources are also needed to ensure full implementation of currently recommended measures to decrease the risk of nosocomial and laboratory-acquired TBPIP: This review considers the occupational hazard to health care workers posed by the global increase in tuberculosis (TB), especially in multidrug-resistant TB . The review opens by focusing on the following aspects of TB in industrialized countries: the risk of TB among health care workers, reasons for the increase in nosocomial TB, which health care workers are most at risk, and effective interventions to reduce nosocomial TB transmission . Next, the review turns to developing countries, using Africa South of the Sahara as an example and considering the impact of AIDS and TB and the risk of nosocomial transmission to health workers . The review then notes that the measures used to control nosocomial TB in developed countries are not generally affordable in developing countries and discusses the following 1993 guidelines offered by the World Health Organization to address this problem as well as practical measures introduced in some African hospitals that 1) improve the diagnosis and treatment of TB patients, 2) involve appropriate environmental control, and 3) institutionalize the means of personally protecting health care workers . It is concluded that operations research is needed to test and evaluate inexpensive, sustainable, and cost-effective control measures in low-resource settings and that health care workers are a vital resource and must be protected against this occupational risk . Blood, 1998 Feb 1, 91(3), 1001 - 7 Cyclosporin A induces apoptosis in childhood acute lymphoblastic leukemia cells; Ito C et al.; In an effort to identify novel antileukemic agents that can bypass the mechanisms of multidrug resistance, we found that cyclosporin A ({CyA} 5 mumol/L) produced a median cell kill of 69% (range, 47% to 85%) in seven B-lineage acute lymphoblastic leukemia (ALL) cell lines (OP-1, SUP-B15, KOPN-55bi, RS4;11, NALM6, REH, and 380) and three T-lineage ALL cell lines (MOLT4, CCRF-CEM, and CEM-C7) after 4 days of culture . At 10 mumol/L, median CyA toxicity was 99% (range, 88% to > 99%) . CyA was equally toxic to both a multidrug-resistant cell line, CEM-VLB100, which overexpresses gp-170 P-glycoprotein, and one resistant to topoisomerase II inhibitors, CEM-VM1-5, which has a mutation in the topoisomerase II gene . CyA was also toxic to primary leukemic cells maintained in stroma-based culture, a system that substantially prolongs in vitro cell survival . Against lymphoblasts from 21 patients with B-lineage ALL, the compound (at 5 mumol/L) reduced the leukemic cell number by a median of 87% (range, 27% to > 99%) compared with results for parallel control cultures lacking CyA . Seven of these samples were from cases with unfavorable genetic features (e.g., Philadelphia-chromosome or MLL gene rearrangements); three were obtained at relapse . Against T lymphoblasts (from six patients), the median reduction in cell number was 79% (range, 30% to > 99%) . At 10 mumol/L, the cell kill exceeded 97% in all cases studied . The mechanism of CyA cytotoxicity was found to be the activation of apoptosis, which was suppressed by phorbol myristate acetate but not by inhibitors of ceramide-mediated apoptosis, phosphatidyl inositol-3 kinase activity, or tyrosine kinase activity . These findings demonstrate high levels of CyA-induced toxicity against ALL cells at concentrations achievable in vivo, thus providing a strong rationale for clinical testing of this agent in patients with ALL. Tumori, 1997 Sep-Oct, 83(5 Suppl), S21 - 4 {SDZ PSC 833: a novel modulator of MDR}; Covelli A; SDZ PSC 833 is a novel compound able to reverse the resistance to chemotherapy of cancer cells with the multidrug resistance (MDR) phenotype by inhibiting the 170 kd P-glyco-protein (P-gp) . In vitro studies show that SDZ PSC 833 directly interacts with, but is not transported by P-gp, although the exact mechanism of action has not yet been defined . In cells with the MDR phenotype, intracellular concentration of various P-gp-transported anticancer drugs is restored to the same level as in sensitive cells by SDZ PSC 833 concentrations of 0.8 microM to 3.0 microM . In vivo SDZ PSC 833 was highly active in potentiating the anti-tumour activity of all tested anticancer drugs (ACs) in both sensitive and MDR tumours . Sensitivity of non-MDR tumours was increased by SDZ PSC 833 through pharmacokinetic interactions, that result in enhanced area-under-the-curve (AUC) of P-gp-transported ACs . However, an increased AC bioavailability is not sufficient to explain the therapeutic benefit of SDZ PSC 833 co-treatment in MDR tumour-bearing mice: in these animals, no survival increase could be achieved with the AC alone by simply increasing the cytotoxin dosage up to doses that were severely toxic for the non-tumour-bearing mice . In a series of phase I/II studies, the recommended doses of SDZ PSC 833 were established at: 10 mg/kg/day i.v . as a 24-hour continuous infusion after a 2 mg/kg loading dose as a 2-hour infusion; 20 mg/kg orally divided four times daily in solid tumours or 16 mg/kg orally divided four times daily in multiple myeloma . The dose limiting toxicity of SDZ PSC 833 is ataxia, which appears to be reversible and dose-related . Moreover, a predictable change in pharmacokinetic parameters of concomitantly administered P-gp-transported AC(s) which usually necessitate a 30-60% reduction from the standard dose of the AC in order to maintain the same time-exposure and dose-related toxicity of the cytotoxic drug alone . The results of experiments both in vitro and in vivo suggested that adequate blood levels (i.e . > or = 1.0 microM) of SDZ PSC 833 must be reached before and maintained during the administration of concomitant AC(s), in order to maximally reverse MDR . At the recommended doses, blood concentrations exceeding 1000 ng/mL (1.0 microM) can be achieved after both i.v . and oral administration . Indeed, SDZ PSC 833 concentrations that fully reverse MDR in vitro are achievable in vivo, plasma samples from patients treated with SDZ PSC 833 restored the sensitivity of MDR human sarcoma cells to paclitaxel, etoposide and doxorubicin . Clinical studies completed so far aimed first to determine the dose of both SDZ PSC 833 and the concomitant AC(s) to be used in ongoing pivotal trials . These studies accrued advanced stage cancer patients, however, tumour responses have been observed in both solid and hematological tumours . The in vitro finding that treatment with SDZ PSC 833 may suppress the activation of the MDR1 gene and prevent the emergence of resistant cancer cell clones with the MDR phenotype might support the use of this MDR modulator in earlier stages of disease. Tumori, 1997 Sep-Oct, 83(5 Suppl), S17 - 20 {Treatment of multidrug resistance in oncology and hematology}; Petrini M et al.; BACKGROUND: Drug resistance, which often occurs also during chemotherapy, is yet a great obstacle to the success of the human malignancies treatments . Among many possible mechanisms of drug resistance (biological, biochemical, kinetic or pharmacological), both typical and atypical multidrug-resistance (MDR) have been extensively studied . Multidrug resistance is the phenomenon whereby the development of resistance to one drug is accompanied by the simultaneous development of resistance to a variety of structurally unrelated drugs . Typical MDR seems to depend on the expression of an 170 KD protein, the P-170 or P-glycoprotein, that acts as an energy-dependent pump removing possible toxic agents, including antiblastic drugs, from the cell . High levels of the mdr1 expression have been found in normal adrenal gland, kidney, colon, jejunum and liver, whereas low levels were detected in skin, muscle, brain, nervous system and bone marrow, where CD34+ stem cells are P-170 positive . Moreover, heat shock proteins or oncogene transfection, cell differentiation or proliferation could modulate the P-glycoprotein expression: low protein levels were described in resting B lymphocytes and monoblast cells, whereas plasma cells and monocytes express higher P-170 levels . On the contrary, more differentiated myeloid cells show a low MDR1 expression . METHODS: Since normal kidney and haematopoietic cells physiologically express P-170 protein, 20 renal cell carcinomas at the surgery and many hematological patients were evaluated in this study, including acute leukemias, chronic myeloid, chronic lymphocytic leukemias and multiple myeloma . Moreover we evaluated the MDR expression in 23 non small cell lung cancers . The MDR1 gene expression was showed by RT-PCR assays, whereas the P-170 protein was detected by immunological and cytofluorometric reactions employing the C-219 and JSB1 monoclonal antibodies . RESULTS AND CONCLUSIONS: Of the 32 acute leukemia patients, 15 (47%) resulted P-170 positive; 14 out of the 15 positive, but 12 out of the 17 negative cases were resistant to the chemotherapy, with an higher positivity in monoblastic types; on the contrary, all lymphoblastic leukemias resulted P-170 negative and only 2 of 13 patients resulted drug resistant . A very high MDR expression was showed in chronic disorders: in the lymphocytic ones, only samples CD5/CD19 negative (3 of 42) resulted P-170 negative, confirming the basal MDR phenotype expression . In these cases, nevertheless, the protein expression was not related to the treatment response . Also in the multiple myeloma patients, no relations between clinic parameters and P-170 expression were found; however a significant relationship between treatment response and P170 expression was found . In kidney and lung cancer samples examined, a low percentage of positive samples was detected without any relationship to the evaluated clinical parameters. Leuk Res, 1997 Nov-Dec, 21(11-12), 1077 - 86 The MDR1 (P-glycoprotein) and MRP (P-190) transporters do not play a major role in the intrinsic multiple drug resistance of Jurkat T lymphocytes; Martel J et al.; The response of T cells in relation to the cell cycle has not been extensively studied . We have attempted to address this question using Jurkat T cells treated with cytostatic drugs known to arrest cells at various transition points of their cycle . We tested several concentrations of drugs that act at G1/S (hydroxyurea, lovastatin, thymidine), early S (aphidicolin, cyclosporin A, rapamycin) or G2+M (colchicine, nocodazole) in 24 h cultures . Cytofluorimetric analyses showed that cycling Jurkat cells were equally distributed between the G1 (44.9 +/- 6.5%) and S (42.3 +/- 8.0%) phases . Cell distribution in G2+M was 12.7 +/- 2.8% . Hydroxyurea but not lovastatin increased the percentage of cells in S phase to approximately 60-70% and both drugs decreased it to approximately 30% in G1 . Thymidine had no effects . Aphidicolin increased the distribution in S phase to approximately 70% with a decrease in G1 to approximately 30% . Cyclosporin A and rapamycin increased the percentage of the cells in G1 to approximately 70% and decreased it to approximately 25% in S phase . Nocodazole increased cell distribution in G2+M to approximately 60% and induced a decrease in G1 to approximately 10% . The effects of the drugs were not related to their toxicity and their limited efficiency raised the possibility that Jurkat cells possessed an intrinsic resistance to these xenobiotics . Time-course analysis showed (scanning electron microscopy) that the early morphological changes induced by colchicine were reversible . Drug efflux experiments (vinblastine) suggested that an ATP-dependent process could be involved . However, Northern blot analyses showed a weak signal for MDR1 (P-glycoprotein) . In contrast, a probe for MRP (P-190) showed a strong signal in Jurkat and peripheral lymphocytes . The presence of drugs (cyclosporin A, nocodazole, thymidine) (24 h) did not upregulate its message and cell treatment with DL-butathione (S,R)-sulfoximine only moderately affected the efficiency of the glutathione S-conjugate MRP transporter . Our data suggest that the intrinsic multidrug resistance of leukemic Jurkat T cells does not appear to involve the MDR1 and MRP members of the ABC family of reverse drug transporters and these observations raise the possibility of the involvement of multifaceted mechanisms. Southeast Asian J Trop Med Public Health, 1997 Jun, 28(2), 387 - 90 Kat G mutations in isoniazid resistant Mycobacterium tuberculosis isolates from Thai patients; Paca-uccaralertkun S et al.; Isoniazid resistant mechanisms in Mycobacterium tuberculosis have been shown to involve at least two genes, kat G and inh A . Alteration in the kat G gene has been found in a great number of resistant isolates . Percentage of resistant isolates harboring alteration in this gene varied among laboratories suggesting that different mutations were presented in different geographic areas . Fourteen isoniazid resistant and five multidrug resistant isolates from the Central Chest Hospital, Thailand, were examined for the kat G gene mutations in the region between base position 17 to 299 . No different pattern of mutations were found between these two groups . Among nineteen isolates, there were nine isolates which showed point mutations and five isolates with base insertions of the kat G gene . The remaining five isolates revealed gene deletion . Heteroduplex formation technique also confirmed base alterations in these nine mutants. Mol Pharmacol, 1998 Jan, 53(1), 141 - 7 Kinetics of anthracycline efflux from multidrug resistance protein-expressing cancer cells compared with P-glycoprotein-expressing cancer cells; Marbeuf-Gueye C et al.; The multidrug resistance protein (MRP) has been shown to mediate ATP-dependent efflux of anticancer agents of diverse structure, such as daunorubicin (DNR), vincristine and etoposide . Thus, this protein does confer a multidrug resistant phenotype to cancer cells, similar to P-glycoprotein (Pgp) . The substrate specificity of both transporter proteins is partly overlapping but is otherwise very distinct; because MRP is a multiple organic anion transporter, it transports certain glutathione conjugates and may be partly dependent on intracellular glutathione levels for the transport of anthracyclines . We have studied the transport kinetics of a series of anthracyclines in MRP and Pgp that overexpress tumor cell lines to obtain information on the substrate specificity of these proteins . The anthracyclines have modifications in the sugar moiety . The mean active efflux coefficient Ka, used to characterize the efficiency of the active efflux, was very similar for DNR and one of its 4'-deoxy-derivatives (eso-DNR) for MRP and Pgp {10-20 x 10(-10)/sec/(cells/ml)} . The permanently neutral derivatives 3'-deamino-3'-hydroxy-doxorubicin (OH-DOX) and 3'-deamino-3'-hydroxy-daunorubicin (OH-DNR) were effluxed by both proteins but had a lower Ka {2 x 10(-10) and 6 x 10(-10)/sec/(cells/ml) (OH-DOX)} and 2 x 10(-10) and 5 x 10(-10)/sec/(cells/ml) (OH-DNR)} for MRP and Pgp . Two anthracyclines, the doxorubicin derivative pirarubicin and 2'-bromo-4'-epi-DNR seemed to have a slightly higher Ka value for Pgp than for MRP . The apparent Michaelis-Menten constants (K(m)) and maximal efflux rates (VM) for the active transport were within a narrow range for both transporters, except for OH-DOX and OH-DNR, which had a lower VM in the case of MRP-mediated transport, suggesting a role of the amino group in the interaction with glutathione . Determination of the Hill coefficient (nH) of the MRP-mediated efflux gave most values close to 2, which suggests cooperativity of the transport of anthracyclines as reported before for Pgp . In conclusion, the transport kinetics of anthracyclines by MRP and Pgp are very similar. J Nucl Med, 1998 Jan, 39(1), 91 - 4 Technetium-99m-MIBI uptake in small cell lung cancer; Bom HS et al.; Patients with small cell lung cancer (SCLC) often fail to respond to chemotherapy due to multidrug resistance (MDR) . Technetium-99m-MIBI was reported to be a suitable transport substrate of P-glycoprotein, which is a cytoplasmic membrane protein encoded by the MDR gene . The purpose of this study was to evaluate whether or not the degree of MIBI uptake in SCLC or its retention on delayed imaging correlated with response to chemotherapy . METHODS: Twenty-five patients (19 men, 6 women; mean age 59 +/- 10 yr) with biopsy-proven SCLC had MIBI SPECT 3-7 days before starting chemotherapy . Imaging was acquired 1 and 4 hr after injection of 740 MBq MIBI using a single-head rotating gamma camera . Tumor-to-normal lung uptake ratio (T/NL) was measured . Percent retention (%R) was measured as: %R = 100 x (T/NL at 4 hr)/(T/NL at 1 hr) . All patients received VAP chemotherapy (VP-16 100 mg/m2, adriamycin 40 mg/m2, cisplatin 25 mg/m2) every 4 wk for at least three times . Response to chemotherapy was grouped as complete remission, partial remission and no remission according to the change of tumor size on chest radiograph and CT images . Differences in T/NL and %R among the three groups were analyzed using ANOVA . RESULTS: T/NL of patients with complete remission (n = 7) and partial remission (n = 10) were significantly higher than that of no remission (n = 8) in 1 hr and 4 hr . T/NL at 1 hr in three groups were 2.75 +/- 0.78, 2.35 +/- 0.31 and 1.65 +/- 0.36, respectively . T/NL at 4 hr in three groups was 2.61 +/- 0.94, 2.48 +/- 0.50 and 1.66 +/- 0.42, respectively . However, %R was not different among three groups . Percent retention in three groups was 109.40 +/- 22.10, 96.71 +/- 14.25 and 103.59 +/- 28.43, respectively . CONCLUSION: SCLC with a higher MIBI uptake was more likely to respond to chemotherapy than that with a lower uptake . However, there was a considerable overlap of MIBI uptake among subjects . No significant correlation between the MIBI retention between 1 hr and 4 hr, and the response to chemotherapy was noted. J Nucl Med, 1998 Jan, 39(1), 77 - 86 Novel technetium (III)-Q complexes for functional imaging of multidrug resistance (MDR1) P-glycoprotein; Crankshaw CL et al.; Overexpression of the multidrug resistance (MDR1) P-glycoprotein (Pgp) correlates with cancer chemotherapeutic failure . Lipophilic cationic radiopharmaceuticals such as 99mTc-sestamibi, 99mTc-tetrofosmin and 99Tc-furifosmin (Tc-Q12) have been validated as transport substrates for the MDR1 Pgp and may enable functional imaging of the MDR phenotype in cancer by observing enhanced washout rates of the tracers in those tumor areas expressing Pgp . To further explore and optimize the Pgp recognition properties of Schiff base phosphine mixed-ligand complexes of the Tc-Q series of nonreducible (Tc(III) cations, a variety of Tc-Q complexes were synthesized and tested in vitro for recognition as transport substrates by the human MDR1 Pgp . METHODS: Tracer assays with human drug-sensitive KB-3-1 epidermal carcinoma and MDR KB-8-5 cells expressing nonimmunodetectable and modest levels of MDR1 Pgp, respectively, were used to screen and pharmacologically characterize 37 novel 99mTc-Q analogs . RESULTS: The ideal agent should have low nonspecific binding, high distinction in net uptake between drug-sensitive cells and MDR tumor cells, and high enhancement of uptake in resistant cells after treatment with an MDR modulator, indicating selective blockade of Pgp-mediated efflux of the radiotracer . Three analogs, trans-{5,5'-(1,2-ethanediyldiimino)bis(2-OEt-2-Me-4-penten-3 -one)}bis{dimethyl(3-OMe-1-propyl)phosphine}99mTc(III) (99mTc-Q63) and two trans-{bis(methyl-bis(3-OMe-1-propyl)phosphine)} analogs (99mTc-Q57 and 99mTc-Q58) displayed transport distinctions between drug-sensitive and MDR cell lines that were equal to or greater than all previously available agents . Cyclosporin A, an MDR modulator, had no significant effect in KB-3-1 cells for these 99mTc-complexes but enhanced tracer accumulations in KB-8-5 cells with IC50 values of approximately 1 microM . In contrast, the non-MDR agents methotrexate and cisplatin had no effect on accumulation of 99mTc-Q complexes and 99mTc-sestamibi in KB-8-5 cells . CONCLUSION: Technetium-99m-Q57, 99mTc-Q58 and 99mTc-Q63 are avid transport substrates recognized by the human MDR1 Pgp, and have enhanced in vitro properties that may enable functional imaging of Pgp in vivo with improved signal-to-noise ratios and tissue contrast compared to currently available agents. Urol Res, 1997, 25(6), 407 - 12 Correlation of expression levels of P-glycoprotein with resistance to adriamycin in a renal adenocarcinoma cell line; Kawamoto S et al.; We have demonstrated that low-level expression of P-glycoprotein (PGP), detectable by reverse transcriptase polymerase chain reaction (RT-PCR) assay and flow cytometric assay, is an important factor in multidrug resistance (MDR) in ACHN cancer cells . In this study, we established a subline highly resistant to adriamycin (ACHN/ADM) from ACHN cells, and determined the correlation between PGP levels and MDR levels using ACHN/ADM cells and their parent ACHN cells . The ACHN/ADM cells showed overexpression of PGP, and sensitivity to antitumor agents was lower than that found in ACHN cells . Intracellular accumulation of ADM in ACHN/ADM cells was approximately half the amount of its accumulation in ACHN cells . Sensitivity to ADM in ACHN/ADM cells was enhanced by chemosensitizers with an increase in intracellular ADM accumulation . These results indicate that PGP levels correlate with MDR levels and suggest that chemotherapy using chemosensitizers might be effective in the treatment of renal cancers with overexpression of PGP. Cancer Chemother Pharmacol, 1997, 41(1), 48 - 52 Pharmacokinetics of the multidrug-resistance-converting drug dexniguldipine and its pyridine metabolite M-1 in the plasma, tumor, and renal tissue of tumor-bearing Wag/Rij rats; Schellens JH et al.; The pharmacokinetics of oral dexniguldipine, a new multidrug-resistance-modifying agent under clinical evaluation, and its pyridine metabolite M-1 were determined in plasma, tumor, and renal tissue in Wag/Rij rats bearing a multidrug-resistant CC531 colon adenocarcinoma tumor under the renal capsule . The pharmacokinetics were studied in four experiments . After a single administration of dexniguldipine (30 mg/kg), tumors and kidneys were collected after 5 (experiment 1), 24 (experiment 2), and 48 h (experiment 3) . In the fourth experiment, dexniguldipine was given once daily for 3 consecutive days at a dose of 30 mg/kg . In all experiments, plasma samples were collected at regular intervals . The concentrations of dexniguldipine and M-1 could be determined in plasma in most of the rats at up to 32 h after drug administration . The area under the curve (AUC) of dexniguldipine and M-1 varied by a factor of 2-6 in the four experiments . High tumor-tissue concentrations of dexniguldipine were observed . The concentrations were highest in the multiple-dose experiment (2014 +/- 1005 ng/g tissue) . High degrees of correlation (> 0.8) were established between the concentrations of dexniguldipine measured in plasma and tumor as well as renal tissue . Overall, tumor-tissue concentrations of M-1 comprised one-third of the dexniguldipine concentrations measured. Cancer Res, 1998 Jan 15, 58(2), 256 - 62 BCL-X expression in multiple myeloma: possible indicator of chemoresistance; Tu Y et al.; Because murine myeloma plasma cells and normal human lymph node plasma cells express BCL-X, we evaluated BCL-X expression in malignant human plasma cells . BCL-X expression was detected in several human myeloma cell lines, as well as in CD38-sorted bone marrow cells obtained from some patients . Only the antiapoptotic long form of BCL-X (BCL-X-L), was detected . Because BCL-X-L expression can protect tumor cells from apoptotic death induced by chemotherapeutic agents, we tested the clinical relevance of expression in 55 archival bone marrow biopsies . The biopsies were stained by immunohistochemistry, and BCL-X expression was correlated with the subsequent response to treatment . BCL-X expression in malignant plasma cells strongly correlated with decreased response rates in patient groups treated with either melphalan and prednisone or vincristine, Adriamycin, and dexamethasone . Response rates were 83-87% in non-BCL-X-expressing cases and 20-31% in BCL-X-expressing cases . In addition, BCL-X expression was more frequent in specimens taken from patients at relapse (77%), when compared to those at initial diagnosis (29%) . Further support for the association of drug resistance with BCL-X-L expression came from studies of the 8226 dox-40 cell line . This line, which expresses p-glycoprotein and serves as a model of multidrug resistance in multiple myeloma cells, demonstrated an up-regulated expression of BCL-X-L, which was relatively specific, in that BCL-2 or BAX expression was not altered . In addition, dox-40 cells demonstrated a generalized resistance to apoptosis that was induced by several different agents . These results indicate that malignant plasma cells can express BCL-X-L and that such expression may be a marker of chemoresistant disease. J Biol Chem, 1998 Jan 23, 273(4), 2098 - 104 Divergent transcriptional control of multidrug resistance genes in Saccharomyces cerevisiae; Hallstrom TC et al.; Improper control of expression of ATP binding cassette transporter-encoding genes is an important contributor to acquisition of multidrug resistance in human tumor cells . In this study, we have analyzed the function of the promoter region of the Saccharomyces cerevisiae YOR1 gene, which encodes an ATP binding cassette transporter protein that is required for multidrug tolerance in S . cerevisiae . Deletion analysis of a YOR1-lacZ fusion gene defines three important transcriptional regulatory elements . Two of these elements serve to positively regulate expression of YOR1, and the third element is a negative regulatory site . One positive element corresponds to a Pdr1p/Pdr3p response element, a site required for transcriptional control by the homologous zinc finger transcription factors Pdr1p and Pdr3p in other promoters . The second positive element is located between nucleotides -535 and -299 and is referred to as UASYOR1 (where UAS is upstream activation sequence) . Interestingly, function of UASYOR1 is inhibited by the downstream negative regulatory site . Promoter fusions constructed between UASYOR1 and the PDR5 promoter, another gene under Pdr1p/Pdr3p control, are active, whereas analogous promoter fusions constructed with the CYC1 promoter are not . This suggests the possibility that UASYOR1 has promoter-specific sequence requirements that are satisfied by another Pdr1p/Pdr3p-regulated gene but not by a heterologous promoter. Semin Cancer Biol, 1997 Jun, 8(3), 205 - 13 Do cMOAT (MRP2), other MRP homologues, and LRP play a role in MDR? Borst P, Kool M, Evers R. The discovery of the Multidrug Resistance-associated Protein (MRP or MRP1) as a GS-X pump able to transport both anionic drug conjugates and unmodified anti-cancer drugs out of the cell, has raised the question whether other members of the MRP family might contribute to drug resistance of human tumours . The most extensively studied member of this family is cMOAT, the canalicular Multispecific Organic Anion Transporter . The substrate specificity of this pump was originally defined by an inborn error in rats, lacking this protein . These rats are mildly hyperbilirubinemic, because of their inability to secrete bilirubin glucuronides into their bile . In addition, they have diminished capacity to secrete a variety of other organic anions . Absence of cMOAT in humans results in an analogous inborn error of metabolism, the Dubin-Johnson syndrome . Attempts to determine the effect of cMOAT on the sensitivity of cells to anti-cancer drugs have run into technical problems . Most cells transfected with a cMOAT cDNA construct and overproducing cMOAT seem unable to transport the protein to the cell surface and are not MDR . However, in polarized kidney cell monolayers cMOAT is correctly routed to the apical cell surface and able to transport vinblastine . Hence, overexpression of cMOAT in cancer cells could potentially lead to drug resistance . In studies of cells selected for drug resistance no correlation was found thus far between cMOAT overexpression and MDR, but there was a positive association with cisplatin resistance, raising the possibility that cMOAT might contribute to cisplatin resistance by mediating excretion of cisplatin-glutathione complexes . This remains to be verified by more direct experiments and clinical studies, however . Database searches have yielded four additional MRP family members, MRP3-6 . The physiological functions of these putative transporters are not yet known and whether they can contribute to drug resistance needs to be determined . Another putative transporter found in many MDR cells not overproducing P-glycoprotein is the Lung Resistance Protein (LRP), which is the major vault protein . Scheper et al have detected LRP in many MDR cell lines and they have shown that elevated LRP values are a strong and independent predictor of unfavourable outcome for several types of drug-treated human tumours . LRP is a cytoplasmic protein and attempts to demonstrate its involvement in drug transport have failed thus far . The possibility that this protein is only an indicator of resistance caused by upregulation of other proteins, rather than a drug transporter, remains open. Semin Cancer Biol, 1997 Jun, 8(3), 193 - 204 Function, evolution and structure of multidrug resistance protein (MRP); Deeley RG et al.; Multidrug Resistance Protein (MRP) confers resistance to natural product drugs when overexpressed in cultured cells . It has also been detected in human tumors and in some cases, expression has been correlated with a poor response to chemotherapy . MRP is present in normal tissues where it probably functions as an active transporter of amphiphilic anions . It is also presumed to transport the drugs to which it confers resistance, but how and in what form has not been resolved . Unlike other members of the ATP Binding Cassette superfamily, MRP and several related proteins have three potential membrane spanning domains . The additional NH2-proximal domain in MRP contains five membrane spanning helices with an extracytosolic NH2-terminus and is essential for transport . Conserved features of gene organization and protein structure suggest that MRP and its related proteins share their ancestry with the cystic fibrosis conductance regulator. Semin Cancer Biol, 1997 Jun, 8(3), 143 - 50 ATP hydrolysis cycles and mechanism in P-glycoprotein and CFTR; Senior AE et al.; P-glycoprotein and CFTR are prominent members of the ABC Transporter family . Both use ATP, the former to drive extrusion of drugs from cells and confer multidrug-resistance, the latter to drive opening and closing of anion channels . We compare current working models of catalytic cycle and mechanism of the two proteins . In Pgp the NBDs appear functionally equivalent, in CFTR they appear functionally distinct . In both proteins, ATP hydrolysis occurs in both NBDs, and it is proposed that the two NBDs alternate in catalysis . Other differences and similarities are noted, fostering ideas for future developments. Semin Cancer Biol, 1997 Jun, 8(3), 135 - 42 Structure of the multidrug resistance P-glycoprotein; Higgins CF et al.; In order to elucidate the mechanism by which the multidrug resistance P-glycoprotein extrudes cytotoxic drugs from the cell, and particularly the number and nature of the drug binding site(s), knowledge of the structure of P-gp is essential . A considerable body of genetic and biochemical data has accrued which gives insights into P-gp structure and function . These data are critically reviewed, particularly in relation to the low resolution structure of P-gp which has recently been determined by electron microscopy . P-gp is one of the best characterised of the ABC transporters and these structure-function studies may have more general implications. Int J Tuberc Lung Dis, 1997 Oct, 1(5), 405 - 10 Anti-tuberculosis drug resistance in Madagascar in 1994-1995; Chanteau S et al.; SETTING: A new tuberculosis control programme has been implemented in Madagascar since 1991 . A survey on Mycobacterium tuberculosis resistance to the major drugs was conducted between August 1994 and December 1995 . OBJECTIVE: To determine primary and acquired resistance in pulmonary tuberculosis patients in four main cities . DESIGN: Were included 401 randomly sampled new smear positive patients (36.2% of declared new patients) and 137 recurrent cases (72.9% of declared cases) from 8 centres . Drug susceptibility testing was performed on Lowenstein Jensen medium according to the proportion method . RESULTS: The male to female ratio was 1.35:1 in new patients (age range 11-74 years) and 1.98:1 in recurrent patients (age range 16-76 years) . The primary resistance rate to any drug was 20% (95% Confidence Interval {CI} 16-23) and the acquired resistance rate 40% (95% CI 32-48, P < 2.10(-7) . Primary resistance to one drug was 18% (95% CI 15-22), mainly attributable to streptomycin resistance (14.5%) . Multidrug resistance (MDR) to isoniazid and rifampicin was 0.25% (95% CI 0-0.7) for primary resistance and 5% (95% CI 2.6-10.6) for secondary resistance . No difference was observed between sexes or ages . CONCLUSION: This survey conducted in big cities gives a very negative picture of resistance in Madagascar. Int J Tuberc Lung Dis, 1997 Apr, 1(2), 187 - 90 Cycloserine-induced Stevens-Johnson syndrome in an AIDS patient with multidrug-resistant tuberculosis; Akula SK et al.; We report a case of cycloserine-induced Stevens-Johnson syndrome (SJS) in a 38-year-old male with the acquired immune deficiency syndrome (AIDS) and multidrug resistant tuberculosis (MDR-TB) . The patient developed a cutaneous reaction after 60 days of therapy with ofloxacin, streptomycin (SM), pyrazinamide (PZA), ethambutol (EMB), and cycloserine (CSN) . All drugs were stopped and the rash improved . Due to the severity of his disease, anti-tuberculosis drugs were resumed, one at a time . The patient developed a recurrent rash consistent with SJS, which began when CSN was restarted . CSN was stopped and the SJS began to gradually resolve with palliative treatment despite continuation of the other anti-tuberculosis drugs . However, the patient's overall condition gradually deteriorated and he died . To our knowledge, this is the first case of probable CSN-related SJS. Int J Tuberc Lung Dis, 1997 Feb, 1(1), 59 - 63 Nature of drug resistance and predictors of multidrug-resistant tuberculosis among patients seen at the Philippine General Hospital, Manila, Philippines; Mendoza MT et al.; SETTING: This study was conducted at the University of the Philippines--Philippine General Hospital (UP-PGH), Manila, Philippines . OBJECTIVES: To determine the nature of drug resistance among patients with pulmonary tuberculosis (PTB), and to establish clinical predictors of drug-resistant tuberculosis . DESIGN: Descriptive, prospective study . METHODS: Patients with positive culture for Mycobacterium tuberculosis were interviewed regarding past history of anti-tuberculosis treatment, BCG vaccination, chest X-ray and family contact . M . tuberculosis isolates from 299 patients were tested for susceptibility to rifampicin, isoniazid (INH), ethambutol and streptomycin using the submerged disc proportion method . Pyrazinamide (PZA) susceptibility test was done with standard laboratory powder in 7H10 media . RESULTS: Of the 299 M . tuberculosis isolates, 17% were fully susceptible to the 5 primary drugs and 54% were resistant to 2 or more drugs (multidrug resistant TB {MDR-TB}) . Initial drug resistance rate was high with ethambutol (39%) and INH (17%) . Previous history of anti-tuberculosis treatment was significantly associated with MDR-TB (Odds Ratio {OR} 2.44, 95% confidence interval) . Incomplete anti-TB treatment taken for longer than 3 months increased the likelihood of MDR-TB (OR 4.6, P < 0.0001) . CONCLUSION: The high rate of MDR-TB was associated with previous anti-tuberculosis treatment . The chance of developing MDR-TB was significantly increased when inadequate prior treatment was given for more than 3 months. J Thorac Imaging, 1998 Jan, 13(1), 65 - 71 Radiographic findings and patterns in multidrug-resistant tuberculosis; Fishman JE et al.; Multidrug-resistant tuberculosis (MDR TB) is prevalent in urban areas with large HIV-positive populations . We retrospectively evaluated the chest radiographs of MDR TB patients at presentation and compared them to patients with drug-sensitive tuberculosis (DS TB) . Although the overall radiographic findings and patterns of MDR TB and DS TB were similar, there were significant differences among the MDR TB patients depending on how MDR TB was acquired . Patients who developed MDR TB during an outbreak showed noncavitary consolidations, pleural effusions, and a primary radiographic pattern (70%) . On the other hand, patients who acquired MDR TB due to noncompliance with antituberculous therapy often had cavitary consolidations (50%) and generally demonstrated a postprimary radiographic pattern . Cavitation occurred equally in patients with MDR TB who are HIV positive regardless of CD4 cell count . Chest radiographic findings and patterns in MDR TB are most accurately interpreted in conjunction with clinical history, specifically prior TB treatment . Nevertheless, approximately one-third of patients did not show the "expected" radiographic pattern. J Photochem Photobiol B, 1997 Nov, 41(1-2), 136 - 44 A hydroxypyridinone (CP94) enhances protoporphyrin IX formation in 5-aminolaevulinic acid treated cells; Bech O et al.; Different cell lines were given photodynamic treatment with 5-aminolaevulinic acid (ALA) and light . In addition, the iron chelator 1,2-diethyl-3-hydroxypyridin-4-one (CP94) was used . The porphyrin species produced was spectrofluorimetrically identified as protoporphyrin IX . All the cell lines responded to treatment, including a multidrug resistance gene expressing bladder cancer line and, to a lesser degree, cells derived from untransformed human skin fibroblasts . CP94 enhanced both porphyrin fluorescence, total porphyrin content and photosensitivity of the cells . CCD fluorescence microscopy showed a granular extranuclear porphyrin fluorescence distribution for all the cell lines involved, but the untransformed cells showed a distribution pattern different from the ones seen in the other cells. Jpn J Cancer Res, 1997 Nov, 88(11), 1100 - 7 Combination therapy with antibody and interleukin-2 gene transfer against multidrug-resistant cancer cells; Shinohara T et al.; In the present study, we examined the effect of interleukin-2 (IL-2) gene transfer into multidrug resistance (MDR) cancer cells on the therapeutic efficacy of MRK16 . Human MDR ovarian cancer cells, AD10, were transduced with a bicistronic IL-2 retrovirus, Ha-IL2-IRES-Neo . The G418-resistant population, IL2-AD10, secreted IL-2 into the culture supernatant and did not form a tumor mass in nude mice . The IL2-AD10 cells were more susceptible to the cytotoxicity of murine spleen cells than AD10 cells in vitro . For examination of the effect of IL-2 gene transfer on the antitumor activity of MRK16 against P-glycoprotein-positive tumors, IL2-AD10 cells were co-transplanted s.c . with AD10 cells into nude mice in a ratio of 1:3, and the mice were treated with MRK16 on days 2 and 7 . MRK16 markedly inhibited the growth of AD10 cells mixed with IL2-AD10 cells under conditions (0.3-1 microgram/body) where it showed only marginal effects on the growth of AD10 tumors . These findings suggest that IL-2 gene transfer potentiates the antitumor activity of MRK16 against MDR tumors. Arch Biochem Biophys, 1998 Jan 1, 349(1), 113 - 21 Uncouplers of mitochondrial oxidative phosphorylation are not substrates of the erythrocyte glutathione-S-conjugate pump; Sokal A et al.; Uncouplers of mitochondrial oxidative phosphorylation, dinitrophenol (DNP) and carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), were found to stimulate Mg(2+)-ATPase activity of human erythrocyte membranes in a manner competitive with respect to 2,4-dinitrophenyl-S-glutathione (DNP-SG) which suggested that these compounds may also be substrates of the glutathione-S-conjugate pump . We confirm that the stimulation of erythrocyte membrane ATPase activity by DNP and by another uncoupler, carbonyl cyanide m-chlorophenylhydrazone (CCCP), is competitive with respect to DNP-SG . However, we found no evidence for active transport of DNP and CCCP out of erythrocytes and demonstrate that they inhibit the low-affinity component of DNP-SG transport noncompetitively while stimulating the high-affinity DNP-SG transport (mediated by multidrug resistance-associated protein, MRP1) . Implications of these findings may indicate the electrogenic nature of MRP1-mediated transport of glutathione-S conjugates and stimulation of aminophospholipid translocase (flippase) rather than the glutathione-S-conjugate pump by the uncouplers. Zhonghua Yi Xue Za Zhi (Taipei), 1997 Oct, 60(4), 184 - 90 Expression of DNA topoisomerase II alpha and multidrug resistance p-glycoprotein in acute leukemia; Chiu CF et al.; BACKGROUND: Drug resistance is a major cause of treatment failure in acute leukemia . Overexpression of multidrug resistance gene and decreased activity of topoisomerase II alpha are suggested as two important mechanisms for this resistance . METHODS: We used immunohistochemical method to determine the expressions of both topoisomerase II alpha (topo II alpha) and p-glycoprotein (gp-170) in bone marrow biopsy specimens from 68 cases of acute leukemia . Patients were divided into four groups: (1) leukemia cells with high score for topo II alpha and negative for gp-170; (2) leukemia cells with high score for topo II alpha and positive for gp-170; (3) leukemia cells with low score for topo II alpha and negative for gp-170; and (4) leukemia cells with low score for topo II alpha and positive for gp-170 . The clinical responses were then followed as routine, and the clinical correlation was evaluated by analysis of variance and Pearson Chi-Square test . RESULTS: The measure of the single parameter (either topo II alpha or gp-170 alone) did not show a significant difference in the overall survival . However, the complete response rate was much higher in the first group patients whose bone marrow reading score was high in topo II alpha and negative for gp-170 expression . Survival duration increased with the increase in the complete response rate . CONCLUSIONS: Combined parameters of topo II alpha and gp-170 are more useful than any individual parameter for the prognosis of acute leukemia. Exp Cell Res, 1997 Dec 15, 237(2), 410 - 8 Prolonged weightlessness affects promyelocytic multidrug resistance; Piepmeier EH et al.; An immortalized promyelocytic cell line was studied to detect how doxorubicin uptake is affected by microgravity . The purpose of this experiment was to identify the effect that microgravity may have on multidrug resistance in leukocytes . HL60 cells and HL60 cells resistant to anthracycline (HL60/AR) were grown in RPMI and 10% FBS . Upon reaching orbit in the Space Shuttle Endeavour, the cells were robotically mixed with doxorubicin . Three days after mixing, cells were fixed with paraformaldehyde/glutaraldehyde . Ground control experiments were conducted concurrently using a robot identical to the one used on the Shuttle . Fixed cells were analyzed within 2 weeks of launch . Confocal micrographs identified changes in cell structure (transmittance), drug distribution (fluorescence), and microtubule polymerization (fluorescence) . Flight cells showed a lack of cytoskeletal polymerization resulting in an overall amorphic globular shape . Doxorubicin distribution in ground cells included a large numbers of vesicles relative to flight cells . There was a greater amount of doxorubicin present in flight cells (85% +/- 9.7) than in ground control cells (43% +/- 26) as determined by image analysis . Differences in microtubule formation between flight cells and ground cells could be partially responsible for the differences in drug distribution . Cytoskeletal interactions are critical to the function of P-glycoprotein as a drug efflux pump responsible for multidrug resistance. Exp Cell Res, 1997 Dec 15, 237(2), 307 - 17 Effects of multidrug resistance-related ATP-binding-cassette transporter proteins on the cytoskeletal activity of cytochalasins; Berger W et al.; Cytochalasins are microfilament-active mould metabolites, widely utilized to study the involvement of the actin cytoskeleton in cellular processes as well as in genotoxicity and cell kinetic research . In this study we have investigated whether multidrug-resistance phenotypes, caused by overexpression of the ATP-binding-cassette transporter proteins P-glycoprotein (P-gp) or multidrug-resistance-associated protein (MRP), influence the microfilament-depolymerizing effect of cytochalasins . Using four well-characterized multidrug-resistance cell models, we have shown that both the microfilament-disrupting (phalloidine staining) and the cytotoxic (MTT-assay) activity of cytochalasins are reduced in parallel with increased P-gp expression and restorable by P-gp-modulating agents . This also applied to the cytochalasin D-mediated induction of polykaryons (microscopic evaluation) which arise as a consequence of impaired cytokinesis but unaffected karyokinesis . The reduced cellular activity of cytochalasins in P-gp-positive cell lines was correlated with decreased intracellular accumulation ({3H}cytochalasin B accumulation) which was also restorable by P-gp modulators . Moreover, the dose-dependent inhibition of P-gp photoaffinity labeling ({3H}-azidopine) suggested cytochalasins as P-gp-binding agents . In contrast, MRP overexpression had no effect on either cytochalasin microfilament activity or cytotoxicity . In conclusion, data indicate that the microfilament-destructive effects of cytochalasins are impaired due to a reduction of the intracellular cytochalasin accumulation by P-gp but not by MRP . Results are discussed with regard to P-gp as a resistance factor when cytochalasins are utilized to study microfilament dynamics, cell cycle kinetics or chromosomal damage . Moreover, the polykaryon-inducing activity of cytochalasin D is suggested as a specific indicator for a P-gp-mediated multidrug-resistance phenotype and the reversing potency of chemosensitizers. Invest Ophthalmol Vis Sci, 1998 Jan, 39(1), 164 - 70 Intravitreal daunomycin induces multidrug resistance in proliferative vitreoretinopathy; Esser P et al.; PURPOSE: Adjuvant intravitreal daunomycin is frequently used for the management of proliferative vitreoretinopathy (PVR) . In this study the authors examined whether daunomycin could induce multidrug resistance (MDR), mediated by the mdr-1 gene product P-glycoprotein, in the cells responsible for reproliferation in vivo and in human retinal pigment epithelial (RPE) cells in vitro . METHODS: Expression of P-glycoprotein was examined by immunohistochemistry in surgically removed epiretinal membranes . The cellular source of P-glycoprotein was examined by colabeling for cytokeratin, glial fibrillary acidic protein, and the macrophage marker EBM-11 . P-glycoprotein expression by cultured RPE cells was assessed by reverse transcription-polymerase chain reaction and immunoblot analysis . Daunomycin toxicity was quantified by crystal violet assay . RESULTS: P-glycoprotein expression was detected in 10 of 10 patients pre-exposed to intravitreal daunomycin . In contrast, epiretinal membranes from only 2 of 13 patients never exposed to daunomycin showed faint P-glycoprotein expression . P-glycoprotein expression was strong within 8 months after daunomycin treatment and faded thereafter . Colocalization studies demonstrated predominant expression of P-glycoprotein by RPE cells . Pre-exposure of cultured human RPE cells to subtoxic concentrations of daunomycin induced resistance to daunomycin that was sensitive to the MDR inhibitor, verapamil . Induction of the MDR phenotype in RPE cells by daunomycin was associated with a minor increase in the mdr-1 mRNA level but a prominent increase in P-glycoprotein expression, thus suggesting a primarily translational mechanism of MDR development in human RPE cells . CONCLUSIONS: Intravitreal daunomycin induced P-glycoprotein expression in PVR . Reproliferation in daunomycin-pretreated patients probably necessitates cotreatment with daunomycin and inhibitors of multidrug resistance such as verapamil or administration of antiproliferative drugs such as 5-fluorouracil, which act in a MDR-independent fashion. J Nucl Med, 1997 Dec, 38(12), 1915 - 9 Technetium-99m-furifosmin as an agent for functional imaging of multidrug resistance in tumors; Ballinger JR et al.; There has been a preliminary report that furifosmin, like the other lipophilic 99mTc cations sestamibi and tetrofosmin, is a substrate for P-glycoprotein, the membrane transporter that is a mechanism of multidrug resistance (MDR) in tumors . This has been further investigated in the rat mammary carcinoma cell line MatB/WT and its doxorubicin-selected resistant variant MatB/AdrR . METHODS: In vitro studies were performed by adding furifosmin to stirred single-cell suspensions of MatB/WT and MatB/AdrR in the presence or absence of the Pgp-modulating drug PSC833 . Dynamic imaging studies over 30 min were performed in rats bearing MatB/WT or MatB/AdrR tumors growing in the leg . RESULTS: Accumulation of furifosmin in MatB/AdrR cells in vitro was much lower than that in MatB/WT cells . The addition of 1 microM PSC833 increased the plateau accumulation in MatB/AdrR cells 2.4-fold, but did not affect accumulation in MatB/WT cells . In rats, furifosmin accumulated rapidly in MatB/WT tumors and washed out with a mean t3 of 78 min . Washout from MAtB/AdrR tumors was more rapid, with a t3 of 46 min (p < 0.025) . Following dissection of animals at 30 min, mean tumor-to-muscle ratios were 1.57 and 1.05 in MatB/WT and MatB/ AdrR tumors, respectively (p < 0.025) . CONCLUSION: Furifosmin is suitable for functional imaging of multidrug resistance in tumors. FEBS Lett, 1997 Dec 8, 419(1), 112 - 6 Transport of glutathione prostaglandin A conjugates by the multidrug resistance protein 1; Evers R et al.; The human multidrug resistance protein MRP1 mediates transport of organic substrates conjugated to glutathione, glucuronide, or sulfate . The naturally occurring prostaglandins A1 and A2 can form two diastereomeric glutathione S-conjugates, and it has been speculated that these might be substrates for MRP1 . Here we present evidence that polarized MDCKII cells expressing MRP1 cDNA transport PGA1-GS to the basolateral side of a cell monolayer, in accordance with the lateral localization of human MRP1 in these cells . Furthermore, we show that vesicles made from yeast cells expressing MRP1 cDNA and from mouse erythrocytes (known to contain mrpl) actively accumulate both diastereomers of PGA2-GS with a similar efficiency . Recently, we generated mice with a homozygous mutant mrp1 allele . Uptake of PGA2-GS in vesicles made from erythrocytes of these mice was 3.2 times lower than in wild-type vesicles, but was still significantly above background . This residual transport activity was partly inhibited by methotrexate and cAMP, whereas mrp1-mediated activity was unaffected by these compounds . We conclude that mouse erythrocytes contain at least two transport systems for PGA2-GS . One of these is mrp1; the other one has not been identified yet, but can be inhibited by methotrexate and cAMP. Biochem Biophys Res Commun, 1997 Dec 18, 241(2), 548 - 52 Another link between phospholipid transmembrane migration and ABC transporter gene family, inferred from a rare inherited disorder of phosphatidylserine externalization; Toti F et al.; The mechanisms involved in the maintenance or loss of the asymmetric distribution of phospholipids in the cell plasma membrane remain mysterious . In the yeast Saccharomyces cerevisiae, the transmembrane migration of certain phospholipids is controlled by transcription regulators of various ATP-binding cassette (ABC) transporters . The P-glycoprotein membrane transporters encoded by the multidrug resistance (MDR) genes, members of the ABC protein family, act as lipid translocases in mammalian cells . We report here the lack of expression of MDR genes in lymphoblasts derived from the B cells of a patient with an inherited Scott syndrome, characterized by impaired transmembrane migration of procoagulant phosphatidylserine and hemorrhagic complications . From microsatellite analysis of 7q21.1 and functional assessment, the most likely explanation accounting for Scott phenotype is a mutation in an unlinked gene coding for a regulatory protein necessary for the expression of MDR genes . Because phosphatidylserine externalization is also one of the hallmarks of cells undergoing apoptosis, these observations are suggestive of a relationship between basic processes such as multidrug transport, apoptosis and procoagulant phospholipid exposure. Mol Pharmacol, 1997 Dec, 52(6), 948 - 57 Characterization of a novel bisacridone and comparison with PSC 833 as a potent and poorly reversible modulator of P-glycoprotein; Horton JK et al.; Novel compounds, composed of two acridone moieties connected by a propyl or butyl spacer, were synthesized and tested as potential modulators of P-glycoprotein (P-gp)-mediated multidrug resistance . The propyl derivative 1,3-bis(9-oxoacridin-10-yl)-propane (PBA) was extremely potent and, at a concentration of 1 microM, increased steady state accumulation of vinblastine (VLB) approximately 9-fold in the multidrug-resistant cell line KB8-5 . In contrast to the readily reversible effects of VRP and cyclosporin A on VLB uptake and similar to the effects of the cyclosporin analog PSC 833, this modulation by PBA was not fully reversed 6-8 hr after transfer of cells to PBA-free medium . Continuous exposure to 3 microM PBA was nontoxic and could completely reverse VLB resistance in KB8-5 cells . Consistent with its effects on VLB transport, the drug resistance-modulating effect of PSC 833 was significantly more persistent than that of VRP . However, the effect of PBA was, like that of VRP, rapidly reversed once the modulator was removed from the extracellular environment . PBA was able to compete with radiolabeled azidopine for binding to P-gp and to stimulate P-gp ATPase activity . However, both the steady state accumulation of PBA and the rate of efflux of PBA were similar in drug-sensitive KB3-1 and drug-resistant KB8-5 cells, suggesting that this compound is not efficiently transported by P-gp . These results indicate that PBA represents a new class of potent and poorly reversible synthetic modulators of P-gp-mediated VLB transport. Biochemistry, 1997 Dec 9, 36(49), 15208 - 15 Binding of steroid modulators to recombinant cytosolic domain from mouse P-glycoprotein in close proximity to the ATP site; Dayan G et al.; We recently found that recombinant NBD1 cytosolic domain corresponding to segment 395-581 of mouse mdr1 P-glycoprotein bound fluorescent 2'(3')-N-methylanthraniloyl-ATP (MANT-ATP) with high affinity {Dayan, G., Baubichon-Cortay, H., Jault, J.-M., Cortay, J . -C., Deleage, G., & Di Pietro, A . (1996) J . Biol . Chem . 271, 11652-11658} . The present work shows that a longer 371-705 domain (extended-NBD1), including tryptophan-696 as an intrinsic probe, which bound MANT-ATP with identical affinity, also interacted with steroids known to modulate anticancer drug efflux from P-glycoprotein-positive multidrug-resistant cells . Progesterone, which is not transported, its hydrophobic derivatives medroxyprogesterone acetate and megestrol acetate, and Delta6-progesterone produced nearly a 50% saturating quenching of the domain intrinsic fluorescence, with dissociation constants ranging from 53 to 18 microM . The even more hydrophobic antiprogestin RU 486 produced a complete quenching of tryptophan-696 fluorescence, in contrast to more hydrophilic derivatives of progesterone containing hydroxyl groups at positions 11, 16, 17, and 21 and known to be transported, which produced very little quenching . A similar differential interaction was observed with full-length purified P-glycoprotein . The steroid-binding region within extended-NBD1 appeared distinct from the nucleotide-binding site as the RU 486-induced quenching was neither prevented nor reversed by high ATP concentrations . In contrast, MANT-ATP binding was efficiently prevented or displaced by RU 486, suggesting that the hydrophobic MANT group of the bound nucleotide analogue overlaps, at least partially, the adjacent steroid-binding region revealed by RU 486. J Biol Chem, 1997 Dec 5, 272(49), 30962 - 8 ATPase activity of purified multidrug resistance-associated protein; Chang XB et al.; Human multidrug resistance protein (MRP) was expressed at high levels in stably transfected baby hamster kidney (BHK-21) cells . These cells exhibited a pattern of cross-resistance to several different drugs typical of an MRP-mediated phenotype despite the addition of 10 histidine residues at the C terminus to facilitate purification . Consistent with this functional evidence of the presence of MRP at the surface of these transfectants, strong signals were detected by immunoblotting and immunofluorescence using a specific monoclonal antibody to MRP . There was intense uniform staining of the cell surface as well as weaker staining of intracellular membranes . MRP-containing membranes were solubilized in 1% N-dodecyl-beta-D-maltoside in the presence of 0.4% sheep brain phospholipids . Two sequential affinity purification steps on Ni-NTA agarose and wheat germ agglutinin agarose provided substantial enrichment, and contaminating bands were not detected . ATPase activity of the purified protein was assayed in the presence of the phospholipids, which had been maintained throughout all purification steps . ATP was hydrolyzed in proportion to the amount of purified protein assayed, and typical Michaelis-Menten behavior was exhibited, yielding estimations of Km of approximately 3.0 mM and Vmax of 0.46 micromol mg-1 min-1 . This activity was moderately stimulated by the drugs that others have shown to be transported by MRP-containing membrane vesicles . This stimulation was enhanced by reduced glutathione as is its drug transport, and oxidized glutathione, itself a substrate for transport, caused a strong stimulation . These data describe the first purification of MRP and provide the first direct evidence that the molecule possesses drug-stimulated ATPase activity. J Gen Physiol, 1997 Dec, 110(6), 655 - 64 Octameric stoichiometry of the KATP channel complex; Shyng S et al.; ATP-sensitive potassium (KATP) channels link cellular metabolism to electrical activity in nerve, muscle, and endocrine tissues . They are formed as a functional complex of two unrelated subunits-a member of the Kir inward rectifier potassium channel family, and a sulfonylurea receptor (SUR), a member of the ATP-binding cassette transporter family, which includes cystic fibrosis transmembrane conductance regulators and multidrug resistance protein, regulators of chloride channel activity . This recent discovery has brought together proteins from two very distinct superfamilies in a novel functional complex . The pancreatic KATP channel is probably formed specifically of Kir6.2 and SUR1 isoforms . The relationship between SUR1 and Kir6.2 must be determined to understand how SUR1 and Kir6.2 interact to form this unique channel . We have used mutant Kir6.2 subunits and dimeric (SUR1-Kir6.2) constructs to examine the functional stoichiometry of the KATP channel . The data indicate that the KATP channel pore is lined by four Kir6.2 subunits, and that each Kir6.2 subunit requires one SUR1 subunit to generate a functional channel in an octameric or tetradimeric structure. Br J Pharmacol, 1997 Oct, 122(4), 765 - 71 The multi-drug resistance reversal agent SR33557 and modulation of vinca alkaloid binding to P-glycoprotein by an allosteric interaction; Martin C et al.; 1 . The interaction of the indolizin sulfone SR33557 with the multidrug resistance P-glycoprotein (P-gp), was used to explore the nature of drug binding site(s) on this transporter . The steady-state accumulation of {3H}-vinblastine in P-gp expressing CHrB30 cells was increased by SR33557 with greater potency than verapamil . Furthermore, SR33557 potentiated the affinity of verapamil to modulate vinblastine transport when added simultaneously . 2 . Verapamil elicited a 1.5 to 2.5 fold stimulation of basal ATPase activity in CHrB30 membranes, whereas SR33557 and vinblastine inhibited activity, but only at relatively high concentrations . However, SR33557 and vinblastine decreased the Vmax but not the Km for verapamil stimulation of ATPase activity . This is indicative of a non-competitive interaction, most likely at distinct sites . 3 . The specific {3H}-vinblastine binding to P-gp in CHrB30 cell membranes was displaced by SR33557 with an IC50 of 8.3 +/- 4.5 nM . Moreover, SR33557 caused a 3 fold increase in the dissociation rate of vinblastine binding to P-gp indicating a negative allosteric effect on the vinca alkaloid acceptor site . 4 . These results demonstrate that SR33557 interacts with a site on P-gp which is distinct from, but allosterically linked to the vinca alkaloid site . The apparent broad substrate specificity displayed by P-gp may be explained by a multiple drug binding site model. Tumour Biol, 1998, 19(1), 41 - 51 Comparison between anthracyclines and rhodamine-123 accumulation in chronic lymphoid leukemia: effect of cyclosporin A and verapamil; Maia RC et al.; Multidrug resistance in leukemic cells is associated with decreased drug accumulation . A resistant cell line and cells from 11 patients with chronic lymphoid leukemia B were used for the evaluation of intracellular accumulation of daunorubicin (DNR), idarubicin (IDA), epirubicin (EPI) and rhodamine-123 (Rh-123) . Cyclosporin A (CSA) and verapamil were used to test their modulatory effects on anthracyclines and the fluorescent dye . In leukemic samples there was a tendency for a lower accumulation index in samples tested with Rh-123 as compared to anthracyclines . IDA was a poorer substrate to P-glycoprotein (Pgp) than two of its analogues, e.g . DNR and EPI . A good correlation (80%) was found between Rh-123 accumulation and Pgp expression by phosphatase-anti-alkaline phosphatase . A strict correlation (100%) was found between modulation by CSA of Rh-123 accumulation and immunoreactivity to Pgp . Two discordant results were seen suggesting that other mechanisms of resistance could be present . The Rh-123 accumulation test seems to give a better indication than anthracyclines, however, it is not selective and may allow the detection of other drug-transport pumps. Gan To Kagaku Ryoho, 1997 Dec, 24(15), 2190 - 5 {Structures and functions of xenobiotic efflux pump P-glycoprotein and MRP--important molecular targets for cancer chemotherapy}; Ueda K; This paper deals with the basic features of the xenobiotic efflux pump (P-glycoprotein and MRP) and the clinical significance of the search for specific modulators of these proteins . P-glycoprotein and MRP function as ATP-dependent efflux pumps that extrude cytotoxic drugs from the cells before the drugs reach their intracellular targets, thus conferring resistance to many structurally dissimilar anti-cancer drugs . These proteins are responsible for multidrug resistance of tumor cells, a major obstacle to cancer chemotherapy . To develop well-designed modulators, structural information regarding the specific drug binding sites is important . We recently found that mutations in the putative transmembrane domain (TM) 1 of human P-glycoprotein alter the drug resistance pattern . Some amino acid residues in TM1 together with TM5-6 and TM11-12 may help to govern substrate specificity . The features common to substrates for P-glycoprotein and MRP are also discussed. Cell Growth Differ, 1997 Dec, 8(12), 1243 - 7 Regulation of P-glycoprotein expression in cyclic AMP-dependent protein kinase mutants; Cvijic ME et al.; Multidrug resistance (MDR) in cancer poses a major obstacle to the success of chemotherapy . We previously reported that cyclic AMP (cAMP)-resistant mutants of the Chinese hamster ovary and the mouse adrenal cortical carcinoma cells harboring defective regulatory (RI alpha) subunits of the cAMP-dependent protein kinase (PKA) are more sensitive than wild-type cells to chemotherapeutic agents that are substrates for P-glycoprotein . In addition, a transfectant overexpressing a mutant RI alpha cDNA showed similar increased sensitivity to these drugs . The altered drug sensitivity in the RI alpha mutants results from reduced expression of the mdr gene, suggesting that PKA may regulate its expression . In this study, we evaluated the sensitivity of several Chinese hamster ovary catalytic (C) subunit mutants to various anticancer drugs . Like the RI alpha subunit mutant, the C subunit mutants also exhibit decreased kinase activity and unresponsiveness to growth inhibition by cAMP . However, in contrast to the RI alpha subunit mutant, the C subunit mutants are not multidrug sensitive and maintain P-glycoprotein expression levels comparable to those of wild-type cells . Furthermore, the C subunit mutants display the same resistance patterns as wild-type cells to P-glycoprotein substrates, including Adriamycin, Taxol, and colchicine . No significant difference was observed in their sensitivity to non-MDR drugs, such as 5-fluorodeoxyuridine, between wild-type, RI alpha, and C subunit mutant cells . These results suggest that the increased multidrug sensitivity in the PKA mutant cells results from alteration of the RI alpha subunit and not the kinase activity, thus implying novel functions for the RI alpha subunit . Therefore, genetic alteration of the RI alpha subunit of PKA may modulate drug resistance in cancer. Cancer Res, 1997 Dec 15, 57(24), 5460 - 4 The 95-kilodalton membrane glycoprotein overexpressed in novel multidrug-resistant breast cancer cells is NCA, the nonspecific cross-reacting antigen of carcinoembryonic antigen; Ross DD et al.; Human breast carcinoma MCF-7/AdrVp cells display a novel multidrug resistance phenotype that is characterized by the overexpression of a 95-kDa membrane glycoprotein (p95) and by marked reduction in intracellular anthracycline accumulation, without overexpression of P-glycoprotein or the multidrug resistance protein MRP . p95 is also highly expressed in multidrug-resistant NCI-H1688 cells derived from a human small cell lung carcinoma . Deglycoslyated p95 from NCI-H1688 cells was isolated by two-dimensional gel electrophoresis and then digested with trypsin . The tryptic peptides were analyzed by mass spectrometry and microsequencing . These analyses identified p95 to be identical to NCA-90, the nonspecific cross-reacting antigen related to the carcinoembryonic antigen (CEA) . Further confirmation that p95 is indeed NCA-90 was obtained by Northern and Western blot studies using probes or antibodies specific for p95, NCA-90, or CEA family members . Western blot studies also revealed that CEA itself is overexpressed in MCF-7/AdrVp cells compared to parental MCF-7/W cells . The enforced expression of NCA-90 protein in HeLa cells stably transfected with NCA-90 cDNA did not result in increased resistance of the transfected cells to daunorubicin or a decrease in daunorubicin accumulation in the transfected cells compared to cells transfected only with the expression vector . However, a recent report by H . Kawaharata et al . (Int . J . Cancer, 72: 377-382, 1997) of diminished accumulation, retention, and cytotoxicity of doxorubicin in EJNIH3T3 cells in which enforced expression of CEA was accomplished leaves open the possibility that the overexpression of CEA, possibly in combination with that of NCA-90, could account at least in part for the drug resistant phenotype displayed by MCF-7/AdrVp cells. J Exp Ther Oncol, 1996 Sep, 1(5), 286 - 95 In vitro evaluation of new anticancer drugs, exemplified by vinorelbine, using the fluorometric microculture cytotoxicity assay on human tumor cell lines and patient biopsy cells; Fridborg H et al.; The feasibility of combined studies on a cell-line panel and primary cultures of patient tumor cells in the preclinical evaluation of new anticancer drugs was evaluated in a study of the activity and cross-resistance pattern in vitro of the new semi-synthetic vinca alkaloid vinorelbine (Vrb) . The activity of Vrb was investigated in ten cell lines representing different resistance mechanisms and in a total of 256 fresh human tumor samples, using the fluorometric microculture cytotoxicity assay (FMCA) . Resistance to Vrb in the cell lines was associated with expression of the multidrug resistance-mediating P-glycoprotein and the multidrug resistance-associated protein (MRP) and by a recently described tubulin-associated mechanism, while the cell lines with topoisomerase II- and glutathion-associated resistance did not show decreased sensitivity to the drug . Cross-resistance to vincristine (Vcr) and other tubulin-active agents was high in cell lines as well as in patient cells . As with most commonly used anti-cancer drugs, Vrb was more active in hematological than in solid tumor samples . Among the solid tumors investigated, the highest in vitro response rates were observed in ovarian cancer (27%), sarcoma (25%), non-small cell lung cancer (21%) and bladder cancer (20%), while no response was observed in renal or colorectal cancer . Compared to Vcr, Vrb appeared to be slightly more active in solid tumors and slightly less active in hematological tumors . The results show that although Vrb displays a high degree of cross-resistance to Vcr and other tubulin-active drugs, some difference in the activity spectrum could be detected and that the drug is sensitive to multiple mechanisms of resistance . The results also suggest that leukemias, ovarian cancer, sarcoma and bladder cancer are possible further targets for Vrb . The combination of studies on a cell-line panel and patient tumor cells from a broad spectrum of diagnoses to evaluate a new drug seems feasible and may give information on the mechanism of action and target diagnoses for phase II trials. J Exp Ther Oncol, 1996 Sep, 1(5), 278 - 85 Biochemical consequences of resistance to a recently discovered IMP dehydrogenase inhibitor, benzamide riboside, in human myelogenous leukemia K562 cells; Jayaram HN et al.; Benzamide riboside (BR) exhibits potent antitumor activity in a variety of cultured human tumor cells . The drug is metabolized to benzamide adenine dinucleotide (BAD), which in turn functions as a selective inhibitor of IMP dehydrogenase (IMPDH) activity with a Ki of 0.118 microM . In vitro, BR is a more potent antitumor inhibitor of IMPDH than tiazofurin, another IMPDH inhibitor which has shown significant oncolytic activity in adult patients with end-stage leukemia . To elucidate the mechanism of resistance, a variant of human myelogenous leukemia K562 cells was developed by subculturing sensitive cells in sublethal concentrations of BR over 60 generations . The BR resistant line that emerged exhibited an IC50 (a concentration producing 50% reduction in cell proliferation) of 148 microM, compared to the sensitive line which had an IC50 of 1.6 microM . The activity of the target enzyme, IMPDH, was increased 3-fold in the resistant variant . Studies on BR metabolism revealed that resistant cells formed only 18% of the active metabolite, BAD, compared to sensitive cells . This finding, in turn, correlated with the specific activity of NAD pyrophosphorylase (the enzyme responsible for the synthesis of BAD) which was reduced to undetectable levels in the resistant variant . The basal levels of NAD and guanylates were also significantly decreased to 41% and 48%, respectively, in the resistant line compared to the parent line . Additionally, after treatment with BR a decrease in guanylate level was observed only in the sensitive cells . Sensitive and resistant cells exhibit comparable cytotoxicity to agents outside the tiazofurin family, suggesting that a multidrug resistance was unlikely to explain the resistance to BR . Moreover, BR resistant cells exhibit collatoral sensitivity to 6-aminopurine, cytarabine and 5-fluorouracil, which have different mechanisms of action . In conclusion, these studies establish that the primary mechanism of resistance to BR involves an increase in IMPDH (target enzyme) activity with a concurrent decrease in NAD pyrophosphorylase (BAD synthetic enzyme) activity. J Exp Ther Oncol, 1996 Jul, 1(4), 260 - 70 Behavior of a novel monoclonal antibody for investigation of ovarian cancer and with possible involvement in multiple drug resistance; McGarry Y et al.; Monoclonal antibodies (MAbs) were raised to an ovarian cancer cell line, OAW42, derived from a patient with a histology of serous cystadenocarcinoma of the ovary, in an attempt to identify novel antigens with a possible role in cancer medicine . One antibody P1H10, subclass IgG1, with a high titer was isolated and shown to recognize an antigen of 48 kDa . Enzyme-linked immunosorbent assay and immunocytochemical studies showed the presence of the target antigen in a number of carcinoma cell lines, including lung and breast, and in two out of three frozen breast tissue specimens . The antigen was not detected in normal human lymphocytes and there was minimal binding of the antibody to normal buccal cells . The antigen was not secreted by the OAW42 or the HepG2 cell lines and was not detected in the sera of a number of ovarian cancer patients . Indirect immunofluorescence studies confirmed the localization of the antigen to be intracellular . The binding of the antibody P1H10 to a number of multidrug resistant variants of the OAW42 cell line showed that the presence and the localization of the antigen in the drug-sensitive parental line and resistant variant cell lines was distinctly different and varied with the degree of drug resistance . The relative specificity of the antibody suggests it may be a possible diagnostic agent in human cancer . A possible role of the antigen in multiple drug resistance (MDR) is also suggested. J Exp Ther Oncol, 1996 Jul, 1(4), 251 - 9 Metastatic potential and multidrug resistance correlation in the B16 melanoma system; Staroselsky AN et al.; The question of whether metastatic potential and drug resistance are related phenotypes was addressed by comparing the biological behavior of the parental B16 melanoma and a multidrug resistant variant derived from it, the B16/Col/R . A more pronounced metastatic spread to lungs was observed in mice inoculated i.v . with the B16/Col/R variant than in those bearing the parental line . In addition, in the mice injected with the drug resistant melanoma, unusual tumor masses were observed . Large abdominal and spinal cord growths were seen with the MDR variant but not encountered in mice inoculated with the original B16 melanoma . We further attempted to test the capacity of the two cell types to perform several cellular functions relevant to the metastatic process . The B16/Col/R cells displayed a higher aggregability and cell motility than did the B16 cells . Adherence to endothelial cells was higher in the parental line than in the B16/Col/R, possibly supporting a more efficient extravasation of the variant cells . The drug resistant variant displayed a higher capacity to grow locally in kidney, spleen, cecum and peritoneum, as compared to the parental melanoma, indicating a higher ability of homing and growth in these potential target organs for metastasis . A correlation between metastatic potential and multidrug resistance appears therefore to exist in the system examined. J Exp Ther Oncol, 1996 Jul, 1(4), 226 - 30 Modulation of chemosensitivity by alpha interferon in multiple myeloma and non-Hodgkin's lymphoma; Iaffaioli RV et al.; Low-grade non-Hodgkin's lymphoma and multiple myeloma are chemosensitive malignancies, but are rarely curable because of primary or acquired drug resistance . Interferon has been shown to modulate the multidrug resistance phenotype and to reinduce chemosensitivity in patients with chemoresistant tumors . Fifteen patients with multiple myeloma and 64 patients with low/intermediate grade non-Hodgkin's lymphoma unresponsive to initial chemotherapy were treated with alpha 2b interferon for 2 months . In case of an objective response, treatment was continued until disease progression; non-responding patients received the same chemotherapy to which they were resistant, preceded by a 5 day course of interferon . Interferon salvage monotherapy induced an objective response in 1/15 patients with multiple myeloma and in 7/64 patients with non-Hodgkin's lymphoma . An objective response was achieved after retreatment with first-line chemotherapy preceded by interferon in 4/14 patients (28.6%) with multiple myeloma and in 20/56 evaluable patients (35.7%) with non-Hodgkin's lymphoma . Toxicity was moderate, predictable, manageable, and never caused interruption of the treatment . Interferon appears to be able to modulate chemosensitivity of tumors refractory to chemotherapy with several potential mechanisms, including an effect on drug accumulation; its utilization in this setting warrants further evaluation. J Exp Ther Oncol, 1996 Jan, 1(1), 49 - 61 Ultrastructural changes related to multidrug resistance in CEM cells: role of cytoplasmic vesicles in drug exclusion; Bobichon H et al.; The multidrug resistance phenotype is found to be frequently associated with the overexpression of proteins which lead to a decrease of drug accumulation within human tumor cells . A 170 kDa membrane glycoprotein which is related to the overexpression of the mdr1 gene is inserted in the plasma membrane and pumps the cytotoxic drugs out of the cells . The aim of this work was to study the morphological modifications of resistant CEM/VLB 100 cells relative to their parental drug-sensitive ones and the detection of the ultrastructural localization of P-glycoprotein at the cytoplasmic level . Using a scanning electron microscope, CEM resistant cells showed wide smooth protrusions while CEM sensitive cells showed microvilli and fine folds . With transmission electron microscopy, an enhanced secretory system was observed in CEM resistant cells: both electron transparent and electron opaque vesicles were associated with the Golgi system, revealed by wheat germ agglutinin-colloidal gold labelling . These vesicles were the binding site of C 219 and MRK 16 antimembrane glycoprotein antibodies, and some of them were determined to belong to the lysosomal system after PTA staining . These vesicles may be an additional way to decrease the cellular uptake of drugs in multidrug resistant cells . Moreover, some nuclear and nucleolar modifications were also observed . These observations show that MDR has wide morphological features which concern several organelles. J Exp Ther Oncol, 1996 Jan, 1(1), 39 - 48 Messenger RNA expression of resistance factors in human tumor cell lines after single exposure to radiation; Stammler G et al.; Resistance of tumor cells to chemotherapeutic drugs can not only be caused by treatment with antineoplastic agents but also by radiotherapy . The aim of this study was to analyze whether ionizing radiation can influence the mRNA expression of proteins which have been found to be involved in drug resistance of tumor cells . Human tumor cell lines (MCF-7, LXF and Sk-Mel) were treated with single doses of irradiation (5, 10 and 20 Gy) . The expression of the resistance related proteins glutathione S-transferase-pi (GST-pi), topoisomerase II alpha (Topo II), thymidylate synthase (TS), O6-methylguanine-DNA-methyltransferase (MGMT), P-glycoprotein (Pgp), glutathione peroxidase (GPX) multidrug resistance-associated protein (MRP) and also of the heat-shock protein 70 (HSP 70) were determined at the mRNA level during the time interval from 1.5 to 72 h post-irradiation and compared with their corresponding controls . We also examined whether a relationship exists between these proteins and the proliferative activity (histone 3, Ki-67, statin) of the cells . We found that exposure of MCF-7, LXF and Sk-Mel cells to ionizing radiation increases the expression of the mRNA of GST-pi . Topo II, TS, HSP 70 and proliferation markers were also altered by exposure to ionizing radiation, but there was no common response of the three cell lines . No significant changes were observed in the expression of MGMT, Pgp, GPX and MRP after radiation treatment . Drug resistance tests revealed that irradiated MCF 7 cells were less sensitive to doxorubicin than non-irradiated control cells . Our results indicate that ionizing irradiation modifies the expression of some proteins involved in drug resistance and the response of MCF 7 cells to doxorubicin and may, therefore, play a role in clinical drug response. J Exp Ther Oncol, 1996 Jan, 1(1), 23 - 9 In vivo reversibility of multidrug resistance by the MDR-modulator dexniguldipine (niguldipine derivative B859-35) and by verapamil; Dietel M et al.; The newly synthesized dihydropyridine derivative B859-35 was previously shown in vitro to be highly effective in reversing multidrug resistance (MDR) of P-glycoprotein positive tumor cell lines, such as the adriamycin (ADR) resistant erythroleukemia F4-6RADR cells . In the current study B859-35 was investigated for its efficiency in reversing MDR in an in vivo tumor model for preclinical testing of MDR-modulators . F4-6RADR cells were injected into the right flank of nude mice while the parent cells were injected into the left flank . The animals were treated i.p . with ADR (9.0 mg/kg body weight) combined with B859-35 (5, 10, or 25 mg/kg) or, for comparison and validation, with verapamil (VRP) (75 mg/kg) . The effects of ADR and the MDR-modulator combination were evaluated by histological morphometry of the tumors . While ADR alone was shown to be ineffective in resistant cells, the combinations of ADR + B859-35 as well as of ADR + VRP were highly active in reducing the number of viable cells in the resistant tumor nodule by 67 +/- 9% or by 53 +/- 11% of controls . This model provides evidence that even in vivo, MDR modulators can be effective in reversing drug resistance . In addition, it presents a potentially useful and rapid preclinical system for in vivo studies on the modification of drug resistance. J Exp Ther Oncol, 1996 Jan, 1(1), 13 - 22 Multidrug resistance-modifying components in human plasma with potential clinical significance; Mulder HS et al.; P-Glycoprotein (P-gp) and multidrug resistance protein (MRP) are plasma membrane associated proteins which can confer multidrug resistance (MDR) to cancer cells by lowering the intracellular amount of drug . Although clinical trials with MDR-reverting agents have been initiated, not much attention has been paid to blood components which may modulate the activity of P-gp or MRP . The present investigation was performed to identify and characterize blood components which may influence the drug content and the drug cytotoxicity of MDR cells . Human plasma, from healthy volunteers, was tested for its effects on the daunorubicin (DNR) accumulation and cytotoxicity in the MDR cell lines SW-1573/2R160 (2R160) and GLC4/ADR containing P-gp and MRP, respectively . The data were compared to the effects observed in wild-type cells . MDR-modifying plasma components were isolated by extraction procedures and characterized using ultrafiltration, high-performance liquid chromatography (HPLC) and mass spectrometry . An increase in the proportion of plasma in the culture medium led to a reduction of the ratio between the DNR content of wild-type and corresponding MDR cells . At 100% plasma we observed an increase in the cellular DNR content of 2R160 cells, which was 10-30% (median 18%) of the maximum possible increase induced by well-known MDR-reverting agents, such as verapamil (for GLC4/ADR cells: 10-20%, median 15%) . The DNR cytotoxicity in MDR cells also increased with an increasing amount of plasma included in the culture media . There was neither an increase in the cellular DNR content nor an effect on the DNR cytotoxicity in wild-type cells . Plasma extract analysis by HPLC showed a major peak which increased the DNR content of MDR cells . The HPLC column retention time of this fraction was identical to that of a standard of cortisol and it was further confirmed to be cortisol using mass spectrometry . Moreover, inclusion of a standard of cortisol in culture media induced a similar effect . We analyzed the data for one of the plasma pools and found that blood cortisol was responsible for the MDR-modulating effect only for 35% of the effect of 100% plasma . Other plasma components were responsible for the remaining modulation effect on MDR cells . In conclusion, the DNR pumping activity of P-gp and MRP is inhibited by human plasma, resulting in 10-30% of the maximum possible increase in cellular drug content . Based on cellular pharmacokinetic calculations this percentage will most likely increase at clinical levels of drug resistance (reaching 40-50%) . In one sample blood cortisol accounted for 35% of the effect of plasma on the DNR content in MDR 2R160 cells . These data show the need for additional studies to test plasma samples for their MDR modulating effects before the administration of MDR-reverting agents in chemotherapy . The data suggest that the effectiveness of chemotherapeutic drugs may be enhanced when administered in accordance with the circadian peak of endogenous corticoids. Lancet, 1997 Dec 13, 350(9093), 1738 - 42 Nosocomial transmission of Mycobacterium bovis resistant to 11 drugs in people with advanced HIV-1 infection; Guerrero A et al.; BACKGROUND: Since 1990, several nosocomial outbreaks of multidrug-resistant (MDR) tuberculosis have occurred, none of which have involved Mycobacterium bovis . We describe an epidemic of nosocomial and primary MDR M bovis tuberculosis from December, 1993, to February, 1995, among HIV-1-infected patients in a district of Madrid . METHODS: We undertook genetic characterisation of the M bovis strain and investigated its presence in a tuberculosis epidemic in a Madrid hospital in a case-controlled study . We assessed 19 cases diagnosed with MDR tuberculosis due to M bovis during the study period . For the control group, we randomly selected 33 patients with HIV-1 infection and isolation of a strain of M tuberculosis susceptible to isoniazid, rifampicin, or both, who were treated in Ramon y Cajal Hospital . Infection-control policies and practices were implemented . FINDINGS: We detected 19 cases in HIV-1-infected patients of primary MDR tuberculosis produced by M bovis resistant to 11 antituberculosis drugs . We found phenotypic and genotypic similarities in the strains of M bovis . In the case group, the index case and two other cases had had previous contact with another hospital that had had an MDR tuberculosis outbreak . All patients died after a mean of 44 days (range 2-116), despite multidrug treatment with first-line and second-line antituberculosis drugs . The cases with M bovis MDR tuberculosis were significantly more likely than controls to have been admitted to a hospital ward at the same time as patients already infected with MDR tuberculosis during the 10 months before their diagnosis (adjusted odds ratio 94.6 {95% CI 9.4-956.3}, p < 0.0001) . Advanced HIV-1 immunosuppression was associated with the development of MDR tuberculosis . Implementation of control measures stopped the epidemic . INTERPRETATION: An M bovis primary MDR tuberculosis epidemic that cannot be treated effectively and with high mortality has emerged in Europe and has been transmitted between hospitals. Anticancer Res, 1997 Sep-Oct, 17(5A), 3707 - 11 Evaluation of topoisomerase I catalytic activity as determinant of drug response in human cancer cell lines; Voigt W et al.; The prognostic value of topoisomerase I (Topo I) catalytic activity and expression of the multidrug resistance (MDR) marker P-glycoprotein (Pgp) and multidrug resistance protein (MRP) for in vitro sensitivity to Topo I interactive agents were evaluated . The efficacy of short term (2 h) and long term (24 h) exposures of camptothecin (CPT), two CPT derivatives (SN-22, SN-38) and the indolocarbazole compound NB-506, was determined against human ovarian carcinoma (A2780 and A2780 DX5), human fibrosarcoma (HT1080 and IIT1080/DR4) and human ileocecal carcinoma (HCT-8) . For each cell line the Topo I protein levels and catalytic activity were determined and correlated with drug-induced cytotoxicity . In general, the Topo I protein levels correlated with Topo I catalytic activity . Drug-induced cytotoxicity increased significantly with prolongation of the exposure time . With the 2 h exposure, the multidrug resistant A2780 DX5 cell line (Pgp+, MRP-) was moderately resistant to all four drugs compared to its parental cell line . In case of CPT and SN-22 but not for SN-38 and NB-506, this resistance was no longer detectable following 24 h drug exposure . No resistance was detectable for the multidrug resistant HT1080/DR4 (Pgp-, MRP+) cell line when compared to its parental cell line . With short term exposures a strong trend was observed toward increased cytotoxicity with increased Topo I catalytic activity, especially if this correlation was studied between derivative cell lines (A2780 vs . A2780 DX5 and HT1080 vs . HT1080/DR4) . This correlation weakened when all 5 cell lines and both exposure conditions were considered . Thus, although overall the correlation between Topo I catalytic activity and sensitivity to Topo I interactive drugs between different cell lines is weak, this correlation may be stronger when comparing derivative cell lines . For CPT and SN-22 but not for SN-38 and NB-506, the moderate resistance levels observed in the Pgp-expressing cell line could be negated by prolongation of exposure duration . MRP expression did not effect drug efficacy . The data demonstrate that the importance of Topo I catalytic activity as single prognostic factor for drug response to Topo I interactive agents is weak and that additional mechanisms affecting drug response have to be taken into consideration. Anticancer Res, 1997 Sep-Oct, 17(5A), 3633 - 45 Expression of CD44 standard and isoforms in human breast cancer xenografts and shedding of soluble forms into serum of nude mice; Fichtner I et al.; Standard CD44 (CD44s) and variant isoforms (CD44v) are expressed on different malignant cells and tissues . Their upregulation has been implicated, in the progression and metastasis of malignomas . In this work we addressed the question of whether these molecules are also expressed on xenografted human breast carcinomas and if certain expression patterns are correlated with biological parameters like tumour size, hormone receptor status, histology, growth rate, chemoresistance and microenvironment . Additionally, we were interested in the shedding of soluble CD44 (sCD44) into the blood circulation of tumour bearing nude mice . The human breast carcinomas MCF-7, MCF-7/ADR, 4296 and MDA-MB435, 4134 and 4151 were transplanted subcutaneously (sc.) or into the mammary fat pad (mfp.) of nude mice . The expression of the CD44s, -v6, and -v9 isoforms was determined at different time points on tissue samples by immunohistochemistry or RT-PCR employing human-specific antibodies or primers, respectively . The serum concentration of CD44s and -v6 was measured by human specific ELISAs . All tumours expressed CD44s . The lowest level was observed in the MCF-7 cancer . The CD44v6 and -v9 sequences and epitopes were distinctly expressed in MCF-7/ADR . MDA-MB435, 4134, 4151 and 4296, while MCF-7 lacked these isoforms . The highest serum concentration of the v6 isoform was detected in mice bearing the tumour 4296 with a high tendency for lymphogenic metastasis . The serum levels of sCD44 were in 5/6 xenografts linearly correlated with the tumour size . Interestingly, there was a remarkable difference between the two sublines MCF-7 and MCF-7/ADR: Both the tissue and serum levels of CD44 isoforms indicated that the development of multidrug resistance is accompanied by an alteration in the expression of membrane proteins discussed to be involved in metastasis . There was no relation of tissue expression with the transplantation site and the hormone receptor status of the tumour lines . CD44s and its variant isoforms are expressed in human xenotransplanted breast cancers in very different levels and patterns . The highest expression in the tumour 4296 is related to lymphogenic metastasis while the absence of isoforms in the model MCF-7 is related to non-metastatic behaviour . CD44 is shed into the serum and can be used for monitoring of tumour growth. Anticancer Res, 1997 Sep-Oct, 17(5A), 3531 - 6 Characteristics of human gastric carcinoma cell lines with induced multidrug resistance; Kang MS et al.; In contrast to intrinsic drug resistance, induced multidrug resistance in gastric cancer cells has not been well studied . Therefore, two doxorubicin-resistant cell lines, (SNU-1DOX, SNU-16DOX), were derived in vitro from gastric carcinoma cell lines (SNU-1, SNU-16) respectively, and their characteristics were investigated . These resistances were not associated with overexpression of mdrl, multidrug resistance associated protein 1 (MRP1), pi or liver class of glutathione S transferase (GST pi, GSTL), heat shock protein 70 (HSP70), p53 or transglutaminase C (TGC) . Levels of p21WAF1 RNA and topoisomerase II protein were decreased in the SNU-16DOX, but not in SNU-1DOX . However, the subsequent enzyme activity of topoisomerase II in SNU-16DOX was not decreased, but rather increased in SNU-16DOX . Furthermore, both resistant cell lines showed lower uptake and higher efflux of doxorubicin and induced cross-resistance to etoposide and vincristine in addition to doxorubicin, indicating a multi-drug resistance phenotype . In summary, we report two gastric carcinoma cell lines exhibiting induced multidrug resistance phenotype and suggest that mdrl, MRP1, GST, TGC, HSP70 and p53 do not play important roles in induced drug resistance in these cell lines . The role of changes in topoisomerase II activity and/or protein is still inconclusive, and p21WAF1 is associated with induced multidrug resistance in the SNU-16DOX gastric carcinoma cell line. Anticancer Res, 1997 Sep-Oct, 17(5A), 3493 - 7 Multidrug resistance-associated protein gene expression and drug sensitivity in human lung cancer cells; Narasaki F et al.; Multidrug resistance-associated protein (MRP) mRNA expression and drug sensitivity in lung cancer cells were examined, and the effects of verapamil, a modulating agent for MRP, on drug sensitivity were also tested . Nine cell lines expressed various levels of MRP gene expression but not the MDR1 gene . The levels were higher in non-small cell carcinoma cells (NSCLC) than in small cell carcinoma cells (SCLC) . Clear correlations between the MRP gene level and the sensitivity to etoposide (VP-16) and doxorubicin (Dox) were observed except for one cell line which highly expressed DNA topoisomerase II . Positive correlations between the MRP gene levels in three cell lines and the modulation effects of verapamil in VP-16, Dox, and vincristine were observed . The present results indicate that MRP probably confers intrinsic multidrug resistance in NSCLC rather than in SCLC. Anticancer Res, 1997 Sep-Oct, 17(5A), 3409 - 23 The primary in vitro antitumor screening of "half-mustard type" phenothiazines; Wuonola MA et al.; The antitumor effects of "half-mustard type" phenothiazines were studied on 57 different tumor cell lines, including leukemias, non-small lung cancer, colon, central nervous system, ovarian, renal, breast, and prostate cancer, as well as melanoma cell cultures . Alkyl-urea derivatives of phenothiazines displayed in vitro antitumor activity . The phenothiazine phthalimido derivatives (1-6) were not active on the majority of cancer cell cultures . In contrast, propylureas (9, 11) were active against some leukemia cell types . Only two compounds with the butylene {(CH2)4} linker (10, 12) were active against non-small lung cancer cells . Compounds containing the propylene linker were less effective . On colon cancer lines, tumor cells from the central nervous system and on melanoma cells the same compounds were effective, however, having substituents at the 2-position of phenothiazine seems to be important . Surprisingly, the majority of ovarian cancer cell lines (except one type, IGROVI) and five of eight renal cancer lines were not sensitive to these phenothiazine derivatives . The two butylene linked phenothiazine ureas (10, 12) had moderate antiproliferative action on two renal cancer cell lines . The prostate cancer and some breast cancer cell lines were not sensitive . Nevertheless some breast cancer cell lines were apparently sensitive to CF3-substituted phenothiazine alkylureas . On the basis of these experiments one may postulate that in the case of insensitive cells an mdr-gene encoded multidrug resistance efflux pump is responsible for the resistance . The selectivity or organ cell specificity of the effective phenothiazines will be targeted for improvement in further studies, in order to avoid the general cytotoxic effects of "half mustard type" phenothiazines. Anticancer Res, 1997 Sep-Oct, 17(5A), 3393 - 401 Cytoskeleton alteration in MCF7R cells, a multidrug resistant human breast cancer cell line; Bichat F et al.; Various cytoskeleton modifications are associated with malignant cell transformation and have been used as prognostic factors . A human breast cancer cell line (MCF7S) and its multidrug resistant (MDR) subline (MCF7R) were characterized here for their intermediate filaments (IFs) expression (cytokeratin 8, 18, 19 and vimentin) as a function of their resistance phenotype . Modifications of these cytoskeleton molecules were analyzed by flow cytometry, immunofluorescence, electrophoresis and immunoblotting techniques . Cytokeratins 8 and 18 were similarly expressed in the cell lines . Cytokeratin 19 was expressed in the MCF7S cell line and not in the MCF7R variant, while vimentin was highly expressed in MCF7R and slightly in MCF7S . Analysis of IFs after the addition of doxorubicin (Dox) in the culture medium of MCF7S, showed an increase in cytokeratin 8 filaments . Vimentin expression in MCF7R was not modified in the presence of these different MDR modulators . Acquisition of MDR was associated with an increase and a redistribution of vimentin filaments characterized by a perinuclear polarization . These drug resistance associated changes might derive from different biological processes triggered by chemotherapy . In conclusion, this suggests that this intermediate filament could be a marker associated with chemoresistance or a marker of malignancy in certain epithelial cancers. Anticancer Res, 1997 Sep-Oct, 17(5A), 3329 - 34 Pulsed exposure of SDZ PSC 833 to multidrug resistant P388/ADR and MCF7/ADR cells in the absence of anticancer drugs can fully restore sensitivity to doxorubicin; Krishna R et al.; AIM: An in vitro cellular pharmacological study was undertaken to characterize the latency of modulating activity by the chemosensitizer, PSC 833 . METHODS: PSC 833 was evaluated for cytotoxicity in the MDR P388/ADR and MCF7/ADR cell lines . Cellular uptake levels and intracellular DOX distribution characteristics were assessed by flow cytometry and fluorescence microscopy, respectively . These parameters were correlated with the chemosensitivity of the MDR cells under varying conditions of exposure to PSC 833 and DOX . RESULTS: PSC 833 (1 microM) provided near complete MDR reversal and exhibited significant latent modulating activity indicative of a sustained inhibition of the PGP pump in P388/ADR and MCF7/ADR cells after removal of the MDR modulator . Interestingly, complete latent chemosensitizing activity could be achieved by pu