维拉帕米
柔红霉素
P-糖蛋白
去甲柔比星
流出
药理学
多重耐药
蒽环类
亲脂性
细胞内
吡柔比星
化学
生物化学
生物
化疗
内科学
医学
钙
阿糖胞苷
抗生素
有机化学
癌症
乳腺癌
作者
Samlee Mankhetkorn,Arlette Garnier‐Suillerot
标识
DOI:10.1016/s0014-2999(97)01548-3
摘要
The basic distinguishing feature of all cells expressing functional P-glycoprotein-multidrug resistance is a decrease of steady state drug levels as compared to those in drug-sensitive controls. A variety of small molecules, such as verapamil and cyclosporin A, bind to P-glycoprotein and inhibit its ability to pump out antitumor drugs. The kinetics of P-glycoprotein-mediated efflux of various anthracycline derivatives was measured in multidrug-resistant (MDR) K562 cells in the presence of verapamil. Used for the purpose were daunorubicin, idarubicin and 8-S-fluoro-idarubicin which have the same pKa of deprotonation equal to 8.4, but different lipophilicity, 4′-epi-2′-bromo-daunorubicin which has a lipophilicity which is comparable to that of daunorubicin but a pKa equal to 6.3, pirarubicin with pKa equal to 7.7 and lipophilicity different from that of these derivatives were used. Our data show (1) that verapamil is unable to completely block the P-glycoprotein-mediated efflux of anthracyclines and that 10% of its functionality remains even with high verapamil concentrations, (2) that the ability of verapamil to restore intracellular accumulation of anthracyclines in MDR cells depends on the kinetics of their uptake. With fast kinetics uptake, as is the case for idarubicin, 8-S-fluoro-idarubicin, 4′-epi-2′-bromo-daunorubicin and pirarubicin (which have either a low pKa and/or high lipophilicity), verapamil can restore in multidrug resistant cells an intracellular drug level which is comparable to that observed in sensitive cells. This is not possible when the kinetics of uptake is low as is the case for daunorubicin. Cyclosporin A is a more potent modulator and is able to fully restore daunorubicin accumulation in multidrug resistant cells.
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