title: Potentiation of etoposide and vincristine by two synthetic 1,4-dihydropyridine derivatives in multidrug-resistant and atypical multidrug-resistant human cancer cells.
abstract: Newly synthesized 1,4-dihydropyridine derivatives had been screened to determine whether they could overcome vincristine (VCR)-resistance in VCR-resistant (P388/VCR) leukemia-bearing mice, and six compounds had strong reversing ability among the screened compounds. We further determined whether NK-250 and NK-252 among the six compounds could potentiate cytocidal activities of etoposide (VP16) as well as VCR against both multidrug-resistant (MDR) cell line (VJ-300) and atypical MDR cell line (KB/VM-4). Both VJ-300 and KB/VM-4 were derived from the same parental human cancer KB cell line: VJ-300 cells showed enhanced expression of a MDR-specific glycoprotein of molecular weight of 170,000 Da (gp170) while KB/VM-4 cells were selected as teniposide (VM26)-resistant cell line with no expression of gp170. NK-250 and NK-252 potentiated the cytotoxic action of VCR about 2- to 10-fold against KB and KB/VM-4 cells, and they almost completely reversed VCR-resistance in VJ-300 cells. By contrast, NK-250 and NK-252 potentiated the cytotoxic action of VP16 about 2-fold against KB cells while they reversed 5- to 10-fold VP16-resistance in both VJ-300 and KB/VM-4 cells. The reversal effect by NK-250 and NK-252 of VCR-resistance in VJ-300 cells appeared to be due to enhanced cellular accumulation of radioactive VCR through interaction to 170-kDa P-glycoprotein. The potentiation effects by these dihydropyridines of VCR and VP16 on KB or KB/VM-4 cells also appeared to be due to enhanced accumulation of radioactive VP16 or VCR, but the effects might be mediated through other mechanisms, plausibly enhanced cellular uptake of the drugs.
authors.affiliation: Department of Biochemistry, Oita Medical School, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Watanabe
authors.forename: H
authors.initials: H
authors.lastname: Takano
authors.forename: A
authors.initials: A
authors.lastname: Kiue
authors.forename: K
authors.initials: K
authors.lastname: Kohno
authors.forename: M
authors.initials: M
authors.lastname: Kuwano
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D004095:Dihydropyridines / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000633:toxicity; D004147:Dioxins / Q000494:pharmacology*; D004351:Drug Resistance; D004357:Drug Synergism; D005047:Etoposide / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000633:toxicity; D006801:Humans; D007424:Intracellular Fluid / Q000378:metabolism; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D014316:Tritium; D014407:Tumor Cells, Cultured; D014750:Vincristine / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000633:toxicity
chemical_list: D000970:Antineoplastic Agents; D004095:Dihydropyridines; D004147:Dioxins; D014316:Tritium; C066457:NK 250; C066458:NK 252; D014750:Vincristine; D005047:Etoposide; C038806:1,4-dihydropyridine