Panneerselvam M, Bredehorst R, Vogel C W
Cancer Res. 1987 Sep 1;47(17):4601-7.
The anticancer agent doxorubicin has two different effects on human SK-MEL-170 melanoma cells: the well known direct cytotoxicity and a marked enhancement of their susceptibility to killing by the R24 monoclonal anti-GD3) ganglioside antibody and human complement. This complement-enhancing effect of doxorubicin is also present after covalent immobilization onto glycerol-coated glass beads preventing cellular uptake of the drug (M. Panneerselvam, R. Bredehorst, and C-W. Vogel, Proc. Natl. Acad. Sci. USA, 83: 9144-9148, 1986). In order to investigate the effect of doxorubicin resistance on the complement-enhancing activity of the drug, we have established a doxorubicin-resistant SK-MEL-170 subline. The development of drug resistance in these melanoma cells was associated with multiple phenotypical changes including an increased expression of at least four high molecular weight plasma membrane proteins or glycoproteins with molecular weights of approximately 220,000, 180,000, 150,000, and 130,000, respectively. The drug-resistant cells accumulated doxorubicin at approximately 2-fold lower amounts in accordance with a 2-fold higher efflux of doxorubicin from these cells. The basal complement susceptibility of the doxorubicin-resistant cells was reduced by more than 60% presumably as a result of the observed reduced expression of GD3 sites and decreased binding of C3b. Most importantly, the doxorubicin-resistant cells were also resistant against the complement-enhancing effect of the free and immobilized drug. The two doxorubicin resistance phenomena, the resistance to the cytotoxic and to the complement-enhancing activities of the drug, seem to be fundamentally different: (a) to achieve comparable cytotoxic and complement-enhancing effects on drug-sensitive and -resistant SK-MEL-170 cells, the drug-resistant cells required 178-fold higher concentrations of free doxorubicin for the cytotoxic effect but only 5-fold higher amounts of the free drug and 12-fold higher amounts of the immobilized drug for the complement-enhancing effect; (b) resistance against the cytotoxic activity of doxorubicin is associated with reduced intracellular drug accumulation, while the data obtained with immobilized doxorubicin indicate that resistance to the complement-enhancing activity of the drug is independent of cellular drug uptake. These data suggest that different mechanisms are responsible for the two resistance phenomena in doxorubicin-resistant melanoma cells.
抗癌药物阿霉素对人SK-MEL-170黑色素瘤细胞有两种不同作用：一种是众所周知的直接细胞毒性作用，另一种是显著增强其对R24单克隆抗GD3神经节苷脂抗体和人补体杀伤作用的敏感性。即使将阿霉素共价固定在甘油包被的玻璃珠上以阻止药物被细胞摄取后，其补体增强作用依然存在（M. Panneerselvam、R. Bredehorst和C-W. Vogel，《美国国家科学院院刊》，83: 9144 - 9148，1986）。为了研究阿霉素耐药性对该药物补体增强活性的影响，我们建立了一个阿霉素耐药的SK-MEL-170亚系。这些黑色素瘤细胞耐药性的产生与多种表型变化有关，包括至少四种高分子量质膜蛋白或糖蛋白表达增加，其分子量分别约为220,000、180,000、150,000和130,000。耐药细胞摄取阿霉素的量约低2倍，这与阿霉素从这些细胞中的流出量高2倍一致。阿霉素耐药细胞的基础补体敏感性降低了60%以上，这可能是由于观察到GD3位点表达减少以及C3b结合减少所致。最重要的是，阿霉素耐药细胞对游离和固定化药物的补体增强作用也具有抗性。阿霉素的两种耐药现象，即对药物细胞毒性作用的抗性和对补体增强活性的抗性，似乎在根本上是不同的：（a）为了在药物敏感和耐药的SK-MEL-170细胞上实现可比的细胞毒性和补体增强作用，耐药细胞产生细胞毒性作用所需的游离阿霉素浓度要高178倍，但产生补体增强作用所需的游离药物量仅高5倍，固定化药物量高12倍；（b）对阿霉素细胞毒性活性的抗性与细胞内药物积累减少有关，而用固定化阿霉素获得的数据表明，对药物补体增强活性的抗性与细胞摄取药物无关。这些数据表明，阿霉素耐药黑色素瘤细胞中的两种耐药现象是由不同机制引起的。
