HOTAIR/let-7e/EZH2正反馈环路在上皮性卵巢癌获得性耐药中的作用研究

Cytoreductive surgery combined with platinum-based chemotherapy represents the standard treatment strategy of epithelial ovarian cancer (EOC), but the recurrences due to acquired resistance against chemotherapy agents occur so frequently that the 5-years overall survival in patients with EOC is about 35%. Our previous study showed that EZH2 is an essential regulator of cell sensitivity to cisplatin in EOC. Our pioneer experiments and foreign researchers indicated that high levels of LncRNA HOTAIR expression in cisplatin-resistant EOC are associated with reduced let-7e expression. HOTAIR, act as a competitive endogenous RNA (ceRNA), absorbing let-7e and regulating EZH2 expression. Moreover, EZH2 could positively regulate HOTAIR expression through non-PRC2 dependent pathway. Based on these evidence, we raise a hypothesis that a HOTAIR/let-7e/EZH2 positive feedback pathway exists in EOC which promotes the development of acquired cisplatin-resistance. To verify this hypothesis, several methods, such as luciferase assay, RNA Immunoprecipitation and site-directed mutation, will be used for clarifying the regulation mechanisms between HOTAIR, let-7e and EZH2; the effectiveness of therapy targeting HOTAIR/let-7e/EZH2 pathway will be showed in cisplatin-resistant ovarian cancer cell lines models.

肿瘤细胞减灭术辅以铂为基础的联合化疗是上皮性卵巢癌（EOC）标准治疗方案，而化疗耐药导致的复发是EOC死亡的主要原因。目前已知EZH2是调控EOC顺铂敏感性的重要因子。我们和他人前期研究已经证实：LncRNA HOTAIR在EOC顺铂耐药细胞中高表达，作为ceRNA与let-7e结合，使分子池内的let-7e减少，而let-7e对EZH2有靶向抑制作用，一旦缺失就可产生过量EZH2。进一步研究提示：EOC顺铂耐药细胞中EZH2可能通过非PRC2通路正向调控HOTAIR表达。因此我们推测EOC获得性耐药的进展中可能存在HOTAIR→let-7e→EZH2→HOTAIR正反馈通路，它可能是EZH2实现自身表达调节，推动EOC获得性耐药的重要机制。本课题拟在EOC组织和细胞中验证此通路的完整性，并阐明其机制；加强和阻断此循环通路后检测细胞耐药性的影响，验证该通路作为EOC耐药治疗靶点的有效性。

肿瘤细胞减灭术辅以铂为基础的联合化疗是上皮性卵巢癌(EOC)标准治疗方案，而化疗耐药导致的复发是EOC死亡的主要原因。本课题首先检测了let-7e在EOC组织中的表达，发现let-7e在耐药组织中的表达低于敏感组织，在细胞中也验证了这一点。上调let-7e能够增加卵巢癌细胞对顺铂的敏感性。通过细胞、动物和分子实验证实了let-7e通过抑制DNA损伤修复从而调节卵巢癌细胞对顺铂的敏感性的作用机制。进一步研究发现let-7e靶向作用PARP1调控DNA损伤修复。本课题的研究成果为针对卵巢癌耐药的治疗提供了潜在的靶点。