TMEM16A钙激活氯通道介导辛伐他汀抑制乳腺癌作用的分子机制研究

Statins produce anti-tumor effect, and become a promising novel anti-tumor agent. However, statin lactone produces much stronger anti-tumor effects than statin acid, suggesting that statin lactone may have additional anti-tumor mechanisms that are different from statin acid. The applicant found that compared with simvastatin acid, simvastatin produced much stronger inhibition on breast cancer proliferation, and stronger inhibition on Ca2+-activated Cl- currents mediated by TMEM16A, suggesting that simvastatin may inhibit breast cancer via TMEM16A Ca2+-activated chloride channel. In addition, the applicant found that TMEM16A overexpression promoted breast cancer proliferation, and increased the expression of phosphorylated EGFR and phosphorylated AKT. The purpose of this project is to investigate the mechanisms by which simvastatin inhibits TMEM16A Ca2+-activated chloride channel in breast cancer cells, and to explore the mechanisms by which TMEM16A channel function activates the EGFR/AKT signaling pathway to promote tumorigenesis and progression of breast cancer, and to elucidate the mechanisms by which simvastatin suppresses breast cancer via the TMEM16A/EGFR/AKT signaling pathway in breast cancer cells and in nude mice xenografted with breast cancer cells. We believe that achieving these goals will reveal a novel mechanism by which simvastatin suppresses breast cancer, and provide new theoretical and experimental basis for the development of TMEM16A-targeted drugs for the treatment of breast cancer.

他汀类药物有肿瘤抑制作用，有望成为新的抗肿瘤药物。然而，他汀内酯类药物有比他汀酸类药物更强的抗肿瘤作用，提示他汀内酯类药物可能额外有不同于他汀酸类药物的抗肿瘤机制。申请者发现辛伐他汀比辛伐他汀酸有较强抑制乳腺癌细胞增殖作用，有较强的抑制TMEM16A钙激活氯电流的作用，提示辛伐他汀可能通过抑制TMEM16A抑制乳腺癌。此外，申请者发现TMEM16A过表达促进乳腺癌细胞增殖以及EGFR和AKT磷酸化。本项目拟阐明辛伐他汀抑制乳腺癌细胞TMEM16A钙激活氯通道的机制，验证TMEM16A氯通道功能激活EGFR/AKT信号通路促进乳腺癌发生发展，并在乳腺癌细胞和荷瘤鼠模型上验证辛伐他汀通过TMEM16A/EGFR/AKT信号通路抑制乳腺癌的作用机制。本研究揭示辛伐他汀抗乳腺癌作用的全新机制，为开发靶向TMEM16A的药物用于治疗乳腺癌提供新思路与实验依据。

他汀类药物有肿瘤抑制作用，有望成为新的抗肿瘤药物。本研究考察了辛伐他汀和辛伐他汀酸对TMEM16A不同的抑制作用，初步明确了两者发挥不同作用的关键药效团；确定了辛伐他汀比辛伐他汀酸有较强抑制乳腺癌细胞增殖作用，结合两者抑制TMEM16A钙激活氯电流作用的差异，提示辛伐他汀通过抑制TMEM16A抑制乳腺癌。确定了辛伐他汀呈剂量依赖性和时间依赖性地抑制TMEM16A钙激活氯电流；考察了辛伐他汀抑制乳腺癌细胞TMEM16A钙激活氯通道的作用机制：确认了辛伐他汀与TMEM16A的直接结合模式，通过分子对接以及结合辛伐他汀对TMEM16A的同源蛋白TMEM16B抑制作用的差异，应用定位点突变技术，找到了对两者结合起关键作用的氨基酸残基。统计分析证明了TMEM16A在ER阳性乳腺癌组织中高表达，并且影响乳腺癌的预后；通路分析预测到TMEM16A高表达组基因富集在EGFR信号通路上；确认了TMEM16A钙激活氯通道能够激活乳腺癌细胞EGFR/AKT信号通路；辛伐他汀可以通过TMEM16A/EGFR/AKT1信号通路抑制乳腺癌细胞增殖。本项目研究成果阐明了辛伐他汀通过抑制TMEM16A钙激活氯通道产生抗乳腺癌作用的全新机制，阐明辛伐他汀抑制TMEM16A钙激活氯通道进而抑制EGFR/AKT信号通路的机制，为辛伐他汀抑制乳腺癌的作用机制提供新方向，为深入研究辛伐他汀治疗乳腺癌提供新思路、新策略。辛伐他汀与TMEM16A的构效关系的确定以及关键氨基酸的发现，为新型TMEM16A抑制剂用于治疗乳腺癌提供理论依据。