Côme M G, Skladanowski A, Larsen A K, Laurent G
CJF INSERM 9503, Institut Claudius-Régaud, Toulouse, France.
Br J Cancer. 1999 Mar;79(7-8):1090-7. doi: 10.1038/sj.bjc.6690174.
Exposure of some acute myeloid leukaemia (AML) cells to daunorubicin leads to rapid cell death, whereas other AML cells show natural drug resistance. This has been attributed to expression of functional P-glycoprotein resulting in reduced drug accumulation. However, it has also been proposed that P-glycoprotein-expressing multidrug-resistant (MDR) cells are inherently defective for apoptosis. To distinguish between these different possibilities, we have compared the cell death process in a human AML cell line (HL-60) with a MDR subline (HL-60/Vinc) at doses that yield either similar intracellular daunorubicin concentrations or comparable cytotoxicity. Adjustment of the dose to obtain the same intracellular drug accumulation in the two cell lines did not result in equal cytotoxicity, suggesting the presence of additional resistance mechanisms in the P-glycoprotein-expressing HL-60/Vinc cells. However, at equitoxic doses, similar cell death pathways were observed. In HL-60 cells, daunorubicin induced rapid apoptosis at 0.5-1 microM and delayed mitotic cell death at 0.1 microM. These concentrations are within the clinical dose range. Similarly, HL-60/Vinc cells underwent apoptosis at 50-100 microM daunorubicin and mitotic cell death at 10 microM. These results show, for the first time, that anthracyclines can induce cell death by a dual mechanism in both sensitive and MDR cells. Our results also show that not only the cytotoxicity, but also the kinetics and mechanism of cell death, are dose dependent. Interestingly, regrowth was observed only in association with delayed cell death and the formation of enlarged, often polyploid, cells with micronucleation, suggesting that morphological criteria may be useful to evaluate treatment efficacy in patients with myeloid leukaemias.
某些急性髓系白血病（AML）细胞暴露于柔红霉素会导致快速细胞死亡，而其他AML细胞则表现出天然耐药性。这归因于功能性P-糖蛋白的表达导致药物积累减少。然而，也有人提出表达P-糖蛋白的多药耐药（MDR）细胞在凋亡方面存在固有缺陷。为了区分这些不同的可能性，我们比较了人AML细胞系（HL-60）及其MDR亚系（HL-60/Vinc）在产生相似细胞内柔红霉素浓度或相当细胞毒性的剂量下的细胞死亡过程。调整剂量以使两种细胞系中的细胞内药物积累相同，但并未导致相同的细胞毒性，这表明在表达P-糖蛋白的HL-60/Vinc细胞中存在其他耐药机制。然而，在等毒性剂量下，观察到了相似的细胞死亡途径。在HL-60细胞中，柔红霉素在0.5 - 1 microM时诱导快速凋亡，在0.1 microM时诱导延迟有丝分裂细胞死亡。这些浓度在临床剂量范围内。同样，HL-60/Vinc细胞在50 - 100 microM柔红霉素时发生凋亡，在10 microM时发生有丝分裂细胞死亡。这些结果首次表明，蒽环类药物可通过双重机制在敏感细胞和MDR细胞中诱导细胞死亡。我们的结果还表明，不仅细胞毒性，而且细胞死亡的动力学和机制均呈剂量依赖性。有趣的是，仅在与延迟细胞死亡以及形成增大的、通常为多倍体的、有微核的细胞相关联时观察到再生长，这表明形态学标准可能有助于评估髓系白血病患者的治疗效果。
