Department of Biological and Environmental Science and Technologies, Università del Salento, Lecce, Italy.
J Cell Physiol. 2019 Apr;234(4):4409-4417. doi: 10.1002/jcp.27224. Epub 2018 Aug 25.
Malignant pleural mesothelioma (MPM) is an aggressive malignant tumor in which cisplatin therapy is commonly used, although its effectiveness is limited. It follows that research efforts dedicated to identify promising combinations that can synergistically kill cancer cells are needed. Because we recently demonstrated that ADP inhibits the proliferation of ZL55 cells, an MPM-derived cell line obtained from bioptic samples of asbestos-exposed patients. Our objective in this study was to investigate the hypothesis that ADP also potentiates the cytotoxic activity of cisplatin. Results show that in ZL55 cells ADP enhanced (a) the cytotoxicity of cisplatin by 12-fold, (b) the restraint of cell clonogenic potential cisplatin-mediated, and (c) the number of apoptotic cells. Cisplatin, but not ADP, caused caspases activation; nevertheless, poly(ADP-ribose) polymerase-1 was not only cleaved in cisplatin-treated cells but also in cells treated with ADP alone. Furthermore, ADP, but not cisplatin, decreased mTOR and 6SK phosphorylations. Both ADP and cisplatin increased p53 protein, but ADP was also able to enhance p53 messenger RNA. P53 silencing resulted in a very large decrement of cell death induced by ADP or by cisplatin and reverted ADP effects on mTOR/S6K phosphorylation, suggesting that activated p53 may act as a negative regulator of mTOR. Consistently, the inhibition of mTOR by rapamycin also sensitized cells to cisplatin, and the effects of cisplatin plus rapamycin were identical to those obtained with cisplatin plus ADP. These findings suggest that the combination of ADP and cisplatin may be a promising strategy for the clinical treatment of cisplatin-resistant MPM.
恶性胸膜间皮瘤（MPM）是一种侵袭性恶性肿瘤，常采用顺铂治疗，但疗效有限。因此，需要进行研究，寻找有前途的联合用药方案，以协同杀伤癌细胞。我们最近证实，ADP 可抑制 ZL55 细胞（ZL55 细胞是从接触石棉的患者活检样本中获得的间皮瘤衍生细胞系）的增殖。本研究旨在验证 ADP 是否能增强顺铂的细胞毒性。结果表明，在 ZL55 细胞中，ADP 增强了（a）顺铂的细胞毒性，增强倍数为 12 倍，（b）顺铂介导的细胞集落形成能力的抑制，以及（c）细胞凋亡数量。顺铂而非 ADP 可诱导半胱天冬酶的激活；然而，多聚（ADP-核糖）聚合酶-1 不仅在顺铂处理的细胞中被切割，而且在单独用 ADP 处理的细胞中也被切割。此外，ADP 而非顺铂可降低 mTOR 和 6SK 的磷酸化。ADP 和顺铂均可增加 p53 蛋白，但 ADP 还能增强 p53 mRNA。p53 沉默导致 ADP 或顺铂诱导的细胞死亡大幅减少，并逆转 ADP 对 mTOR/S6K 磷酸化的影响，提示激活的 p53 可能作为 mTOR 的负调控因子。一致地，雷帕霉素抑制 mTOR 也可使细胞对顺铂敏感，并且顺铂加雷帕霉素的作用与顺铂加 ADP 的作用相同。这些发现表明，ADP 和顺铂的联合用药可能是治疗顺铂耐药性 MPM 的一种有前途的临床策略。
