雌激素通过非基因组途径调控钙离子相关蛋白CACNA2D3在子宫内膜癌发生发展中的分子机制探讨

Endometrial cancer (EC) is one of the most common carcinomas of the female reproductive system, however the etiology is not well understood, which results in poor prognosis. EC is in estrogen-dependent. Some reports have shown that estrogen not only initiates the classical genomic pathway through estrogen receptor, but also stimulates the nongenomic effects，including the elevation of intracellular Ca2+，by binding to the G protein-coupled estrogen receptor GPR30. The homeostasis of Ca2+ depends on various calcium channels. It has been reported that CACNA2D3，as the subunits of voltage-gated Ca2+ channels, is heavily methylated in various tumors and functions as a tumor suppressor. However little is revealed about whether CACNA2D3 is involved in estrogen-mediated nongenomic pathway in EC. In this subject, we intend to investigate the way of CACNA2D3 expression activated by estrogen in Ishikawa cells. By means of immunohistochemistry, yeast two-hybrid system, co-immunoprecipitation and electrophoretic mobility shift assay, we screen and identify the proteins interacting with CACNA2D3，and reveal the transcriptional factor directly modulating the expression of CACNA2D3. The study will reveal a new mechanism by which estrogen modulates CACNA2D3 expression to regulate the occurrence of EC through nongenomic pathway, as well as provides a new theoretical basis for EC treatment.

子宫内膜癌是女性生殖道常见的恶性肿瘤，其发生机制尚不完全明了，导致其治疗方式受限和预后不良。雌激素与子宫内膜癌的发生密切相关，研究发现雌激素不仅可以通过核受体ER激活经典的基因组效应，而且可以与G蛋白偶联受体GPR30结合启动非基因组途径。非基因组途径可以激活胞内钙离子信号，其动态平衡的维持依赖于钙离子通道。有报道电压门控钙离子通道辅助亚基CACNA2D3在多种肿瘤中发生甲基化修饰并发挥抑癌基因的功能，但CACNA2D3是否参与子宫内膜癌非基因组效应尚不明确。针对这一问题，本项目以子宫内膜癌细胞为实验材料，采用酵母双杂交、免疫共沉淀及凝胶迁移等手段，结合组织病理学分析，初步探索雌激素调控CACNA2D3表达的分子途径，鉴定与CACNA2D3结合的蛋白及调控CACNA2D3表达的转录因子，阐明雌激素非基因组途径通过CACNA2D3调控子宫内膜癌发病的机理，并为子宫内膜癌的治疗提供新的依据。

子宫内膜癌（endometrial cancer）是最常见的女性生殖系统恶性肿瘤之一。近年来子宫内膜癌发病率有升高趋势，而且年轻患者比例明显增加。目前孕激素已经广泛应用于要求保留生育能力的年轻子宫内膜癌患者，然而孕激素耐药是子宫内膜癌治疗中的一个亟待解决的难题。因此深入探讨子宫内膜癌的发病机制对于孕激素的有效治疗具有重要的指导意义。早期研究报道电压门控钙离子通道蛋白复合物2/亚基家族辅助成员CACNA2D3的甲基化修饰与肿瘤的发生发展密切相关，而其在子宫内膜癌中的功能是未知的。本项目主要围绕CACNA2D3，孕激素和子宫内膜癌的发生发展等三方面开展工作。研究发现CACNA2D3在子宫内膜癌组织和细胞中表达被明显抑制，过表达CACNA2D3明显抑制体内肿瘤生长，体外细胞增殖和迁移而促进细胞凋亡和胞内钙离子信号增强；孕激素注射抑制体内肿瘤生长，并通过CACNA2D3激活Ca2+/p38 MAPK促进细胞凋亡，而抑制PI3K/AKT途径阻止细胞增殖。本研究一方面揭示了CACNA2D3在子宫内膜癌发生发展中的功能及其发挥功能的分子机制，为子宫内膜癌的有效治疗提供靶标；另一方面阐明了孕激素与CACNA2D3的关系以及孕激素治疗子宫内膜癌的作用机理，为孕激素耐药的逆转奠定理论基础。