Ramu A, Pollard H B, Rosario L M
Department of Radiation and Clinical Oncology, Hadassah University Hospital, Jerusalem, Israel.
Int J Cancer. 1989 Sep 15;44(3):539-47. doi: 10.1002/ijc.2910440328.
Multi-drug resistance (MDR) in cancer cells is associated with reduced drug accumulation. Although intensively studied, the mechanism of this process remains ill-defined. We have now developed a new, rapid and quantitative method of measuring uptake of doxorubicin by these cells, in which the fluorescence of accumulated drug is rapidly quenched by DNA in the cell nucleus. Pre-treatment of cells with deoxyribonuclease eliminates DNA from non-viable, permeable cells, and this obviates the spurious fluorescence quenching that made previous application of this technique useless. Our data strongly suggest that the drug passively diffuses into cells. The rate of this diffusion into drug-resistant cells is considerably lower than that found in drug-sensitive cells. The ratio of the rates of drug entry in these cell types could fully account for the differences between the cell lines in doxorubicin growth-inhibitory activity. In these experiments no evidence for the previously proposed active efflux mechanism was found in either cell line.
癌细胞中的多药耐药性（MDR）与药物蓄积减少有关。尽管对此进行了深入研究，但这一过程的机制仍不明确。我们现已开发出一种新的、快速且定量的方法来测量这些细胞对阿霉素的摄取，在该方法中，细胞核中的DNA会迅速淬灭蓄积药物的荧光。用脱氧核糖核酸酶对细胞进行预处理可消除不可存活的、可渗透细胞中的DNA，这避免了导致该技术先前应用无效的假荧光淬灭。我们的数据有力地表明，药物被动扩散进入细胞。这种扩散进入耐药细胞的速率明显低于在药物敏感细胞中发现的速率。这些细胞类型中药物进入速率的比值完全可以解释细胞系在阿霉素生长抑制活性方面的差异。在这些实验中，两种细胞系均未发现先前提出的主动外排机制的证据。
