Cvijic M E, Yang W L, Chin K V
Department of Medicine, Robert Wood Johnson Medical School, UMDNJ, New Brunswick 08901, USA.
Anticancer Res. 1998 Sep-Oct;18(5A):3187-92.
The emergence of cisplatin resistance poses a significant problem to the treatment of a variety of human malignancies. Therefore, understanding the molecular basis of cisplatin resistance could improve the clinical effectiveness of this anticancer agent. Recently, our laboratory has demonstrated that cAMP-dependent protein kinase (PKA) mutants of the Chinese hamster ovary (CHO) and the mouse adrenocortical carcinoma Y1 cells exhibited increased resistance to cisplatin as well as other DNA-damaging drugs. Further studies showed that either the functional inactivation of PKA or the mutation in the regulatory subunit gene may cause increased recognition of cisplatin-damaged DNA and enhanced DNA repair capacity. In this study, we evaluated the role of PKA in modulating cellular sensitivity to cisplatin in a series of PKA mutants of Saccharomyces cerevisiae. Mutants with decreased kinase activity resulting from a srv2 mutation showed no alterations in cisplatin sensitivity. Complementation of TPK1 in a yeast strain containing mutant tpk1 and also tpk2 and tpk3 deletions did not significantly alter its sensitivity to this DNA-damaging agent. Yeast transformants containing increased kinase activity resulting from overexpression of RAS2Val19 or TPK1 and yeast strains having increased kinase activities due to mutations in the BCY1 gene also did not show alterations in their sensitivity to cisplatin. Therefore, results from these studies unambiguously demonstrate that changes in PKA activity have no effect on cisplatin sensitivity in Saccharomyces cerevisiae.
顺铂耐药性的出现给多种人类恶性肿瘤的治疗带来了重大问题。因此，了解顺铂耐药性的分子基础有助于提高这种抗癌药物的临床疗效。最近，我们实验室发现，中国仓鼠卵巢（CHO）细胞和小鼠肾上腺皮质癌Y1细胞的环磷酸腺苷（cAMP）依赖性蛋白激酶（PKA）突变体对顺铂以及其他DNA损伤药物表现出更高的耐药性。进一步研究表明，PKA功能失活或调节亚基基因突变可能会导致对顺铂损伤DNA的识别增加以及DNA修复能力增强。在本研究中，我们评估了PKA在一系列酿酒酵母PKA突变体中调节细胞对顺铂敏感性的作用。由srv2突变导致激酶活性降低的突变体在顺铂敏感性方面没有变化。在含有突变型tpk1以及tpk2和tpk3缺失的酵母菌株中补充TPK1并没有显著改变其对这种DNA损伤剂的敏感性。含有因RAS2Val19过表达而导致激酶活性增加的酵母转化体以及因BCY1基因突变而具有更高激酶活性的酵母菌株对顺铂的敏感性也没有变化。因此，这些研究结果明确表明，PKA活性的变化对酿酒酵母的顺铂敏感性没有影响。
