Schilder R J, Hall L, Monks A, Handel L M, Fornace A J, Ozols R F, Fojo A T, Hamilton T C
Fox Chase Cancer Center, Philadelphia, PA 19111.
Int J Cancer. 1990 Mar 15;45(3):416-22. doi: 10.1002/ijc.2910450306.
Intracellular thiols have been proposed as mediators of resistance to alkylating agents and cisplatin. As metallothionein is the predominant protein thiol, we examined its relationship to cisplatin resistance in human ovarian cancer cell lines. A human ovarian carcinoma cell line, A2780, derived from an untreated patient, was treated with cisplatin in several ways and the induced resistance to cisplatin ranged from 13- to 68-fold. The degree of resistance was dependent upon the method of selection. The drug-resistant cell lines also developed low levels of cross-resistance to cadmium. Additional cell lines established from untreated patients or ovarian cancer patients refractory to cisplatin- and/or carboplatin-containing combination chemotherapy were studied. The most cisplatin-resistant cell lines, OVCAR-8 and -10, were from patients previously treated with intensive chemotherapy. OVCAR-8 was relatively cross-resistant to cadmium while OVCAR-10 appeared relatively sensitive. Cell lines were examined for expression of metallothionein mRNA to evaluate the relationship between cisplatin resistance, cadmium cross-resistance and metallothionein expression. Only two of the cell lines with in vitro-induced resistance to cisplatin, 2780E80 and 2780CP70B3, had detectable metallothionein mRNA. The other cell lines selected in vitro for cisplatin resistance, as well as the parental A2780 ovarian cancer cell line, showed no expression at our level of detection. There was variable expression of metallothionein among the OVCAR cell lines. Cell lines from untreated patients, OVCAR-5 and -7, did express metallothionein, while the most cisplatin-resistant cell lines, OVCAR-8 and -10, did not. We also examined cisplatin induction of metallothionein mRNA in the cell lines. Only 2780CP70B3 among the cell lines with in vitro-induced cisplatin resistance showed increased expression after short-term exposure to cisplatin. OVCAR-4 also had a slight increase in expression after exposure to cisplatin. Mouse C127 cells transfected with a bovine papilloma virus-metallothionein gene construct were compared for cisplatin sensitivity to the same cell type transfected with bovine papilloma virus alone. In this model system, metallothionein expression did not influence cisplatin cytotoxicity. On the basis of these studies, we conclude that there is no causal relationship between metallothionein expression and cisplatin resistance.
细胞内硫醇被认为是对烷化剂和顺铂耐药的介质。由于金属硫蛋白是主要的蛋白质硫醇，我们研究了它与人类卵巢癌细胞系中顺铂耐药性的关系。一个来自未经治疗患者的人卵巢癌细胞系A2780，以几种方式用顺铂处理，诱导的顺铂耐药性范围为13至68倍。耐药程度取决于选择方法。耐药细胞系对镉也产生了低水平的交叉耐药性。对从未经治疗的患者或对含顺铂和/或卡铂的联合化疗难治的卵巢癌患者建立的其他细胞系进行了研究。最耐顺铂的细胞系OVCAR - 8和 - 10来自先前接受过强化化疗的患者。OVCAR - 8对镉相对交叉耐药，而OVCAR - 10似乎相对敏感。检测细胞系中金属硫蛋白mRNA的表达，以评估顺铂耐药性、镉交叉耐药性与金属硫蛋白表达之间的关系。在体外诱导对顺铂耐药的细胞系中，只有2780E80和2780CP70B3这两个细胞系可检测到金属硫蛋白mRNA。在体外选择的其他顺铂耐药细胞系以及亲本A2780卵巢癌细胞系在我们的检测水平上均未显示表达。OVCAR细胞系中金属硫蛋白的表达存在差异。来自未经治疗患者的细胞系OVCAR - 5和 - 7确实表达金属硫蛋白，而最耐顺铂的细胞系OVCAR - 8和 - 10则不表达。我们还检测了细胞系中顺铂对金属硫蛋白mRNA的诱导作用。在体外诱导顺铂耐药的细胞系中，只有2780CP70B3在短期暴露于顺铂后显示表达增加。OVCAR - 4在暴露于顺铂后表达也略有增加。将用牛乳头瘤病毒 - 金属硫蛋白基因构建体转染的小鼠C127细胞与仅用牛乳头瘤病毒转染的相同细胞类型进行顺铂敏感性比较。在这个模型系统中，金属硫蛋白的表达不影响顺铂的细胞毒性。基于这些研究，我们得出结论，金属硫蛋白表达与顺铂耐药性之间没有因果关系。
