miR-497双重靶向抑制Akt/mTOR/P70s6k信号通路逆转卵巢癌顺铂耐药的机制研究

Resistance to platinum-based chemotherapy presents a major obstacle to attempt to improve the prognosis of patients with ovarian cancer. Recently studies showed that Akt/mTOR/P70s6k pathway plays a central role in acquiring cisplatin-resistance of ovarian cancer. Our previously results has demonstrated that the expression level of miR-497 is downregulated, and meantime, the expression levels of mTOR/P70s6k are upregulated in cisplatin-resistant ovarian cancer cell compared with normal ovarian cancer cell. We also found that mTOR and P70s6k are potential targets of miR-497, and overexpression of miR-497 induced cell apoptosis in ovarian cancer cells. Based on these results, we proposed that overexpression of mir-497 sensitizes resistant ovarian cancer cell to cisplatin through down-regulation of mTOR and P70s6k expression. In this study, we aim to investigate the molecule mechanisms of miR-497 dual targeting Akt/mTOR/P70s6k signal pathway in cisplatin-resistant ovarian cancer cells, animal, and human tissue. The discovery of this study will benefit for development of new therapeutic treatment for cisplatin-resistant ovarian cancer.

卵巢癌的顺铂耐药是卵巢肿瘤领域亟待解决的关键科学问题，研究表明Akt/mTOR/P70s6k信号通路与卵巢癌细胞顺铂耐药密切相关。项目组前期研究发现：miR-497在卵巢癌顺铂耐药患者和耐药细胞中低表达，同时伴mTOR/P70s6k高表达；mTOR/P70s6k是miR-497的靶基因；在卵巢癌细胞内上调miR-497的表达能诱导细胞凋亡。据此提出：miR-497通过双重靶向抑制Akt/mTOR/P70s6k信号通路，逆转卵巢癌细胞顺铂耐药性的假说。本项目拟采用卵巢癌顺铂耐药细胞株为研究对象，从细胞、动物和人组织样本水平阐明miR-497逆转卵巢癌顺铂耐药的作用机制，为卵巢癌顺铂耐药治疗提供新的策略和思路。

卵巢癌的铂类耐药是晚期卵巢癌5年生存率低于30%的主要原因，因此对卵巢癌铂类耐药的发生及逆转机制的研究是卵巢肿瘤研究的核心问题，对能否控制卵巢癌、提高患者生存率至关重要。Akt/mTOR/P70s6k信号通路在介导肿瘤细胞生长、增殖凋亡和耐药方面发挥着关键作用。多项研究表明Akt/mTOR/P70s6k信号通路在卵巢癌中异常激活，该通路上的多个关键基因，如Akt、mTOR、P70s6k、4E-BP1的异常表达和卵巢癌上皮间质内转化、化疗耐药及预后不佳显著相关。在本研究中我们通过高通量芯片分析发现卵巢癌顺铂耐药细胞株中miR-497低表达，同时通过分析卵巢癌大型数据库我们发现miR-497与卵巢癌耐药负相关，进一步实验证明miR-497启动子区甲基化是miR-497低表达的原因，表明miR-497在卵巢癌细胞铂类耐药性获得的生物学功能起着极其重要的作用。通过生物信息学分析发现miR-497和mTOR、P70s6k的3’UTR 均存在互补结合序列，并且在卵巢癌细胞中过表达miR-497能显著抑制mTOR、P70s6k的蛋白表达。通过体内体外实验我们证实miR-497可能同时抑制 Akt/mTOR/P70s6k信号通路的两个关键基因mTOR 和P70s6k，进而逆转卵巢癌顺铂耐药性。本研究结果可为miR-497治疗顺铂耐药性卵巢癌提供新的思路和策略。