稀有人参皂苷Rk3诱导雌激素受体阳性乳腺癌细胞凋亡的抗肿瘤作用机制研究

Estrogen receptor positive breast cancer is one of the most comment woman malignant tumors. The discovery of natural anti-cancer medicines with minor side effects is one of the most popular topics in the pharmaceutical field. Our previous researches show that Ginsenoside Rk3 possesses higher anti-cancer activity than other ginsenosies, significantly inhibiting growth and inducing apoptosis in ER positive breast cancer cells. However, the mechanism still remains unclear. Therefore, by using MCF-7 and T47D as cell models, this project is aimed to study the anti-cancer activities of Ginsenoside Rk3, describe the mechanism of Rk3 induced apoptosis and autophagy effects; illustrate mechanisms of the regulation of both PI3K/Akt and steroid receptor signal pathways and the crosstalk between them; elucidate targets and mechanisms of Rk3 anti-cancer activities in an subcutaneous xenotransplanted tumor model of human ER positive breast cancer in nude mice. This project reveals the targets and mechanisms of Rk3 anti-cancer activities against human ER positive breast cancer, expands the theoretical system of ginsenoside action mechanism against human cancer, hence providing theory basis and new ideas to explore and design ginsenoside based anti-cancer drugs.

雌激素受体（ER）阳性乳腺癌是女性最常见的恶性肿瘤，挖掘更有效且副作用小的天然抗癌药物一直是医药领域的核心问题之一。我们的前期研究表明稀有人参皂苷Rk3对于ER阳性乳腺癌具有较其它人参皂苷单体更强的抗肿瘤作用，能够抑制肿瘤细胞增殖诱导凋亡，但作用的分子机制不清楚。本项目拟以MCF-7和T47D细胞为模型，阐明Rk3对人ER阳性乳腺癌的抑制作用，Rk3诱导肿瘤细胞凋亡或自噬作用的分子机制，及二者之间的交互关系；运用分子生物学手段，在细胞水平上阐明Rk3通过类固醇激素受体介导调控PI3K/Akt信号通路活力的非基因组作用机制；利用人乳腺癌裸鼠移植模型研究Rk3在动物整体水平上发挥抗肿瘤作用的靶点及分子机制。本项目明晰了人参皂苷Rk3对ER阳性乳腺癌抗肿瘤活性的作用靶点和作用机制，拓展和完善了现有人参皂苷抗癌作用机制的理论体系，为新型人参皂苷抗癌药物的开发和设计提供理论依据和新思路。

乳腺癌是女性最常见的恶性肿瘤，开发更有效且副作用小的天然抗癌药物是乳腺癌的热点研究内容之一。本项目筛选出具有高抗乳腺癌活性的人参皂苷Rk3，解析其针对乳腺癌抗肿瘤活性的作用靶点和作用机制，主要研究成果如下：. 1．人参皂苷Rk3对在ER阳性乳腺癌细胞MCF-7表现出强烈诱导细胞死亡的作用，并将人ER阳性乳腺癌细胞阻滞在G1期，48h作用后IC50为81.34μM。人参皂苷Rk3通过激活Caspase-9，Caspase-3等半胱氨酸蛋白酶进而诱导乳腺癌细胞凋亡，而且在诱导细胞凋亡的同时具有激活保护性自噬的作用。. 2．稀有人参皂苷Rk3显著下调乳腺癌细胞中磷酸化的PI3K（p-PI3K）、磷酸化的Akt（p-Akt）和磷酸化的mTOR（p-mTOR）蛋白表达水平，这种调控作用呈现出剂量与时间依赖效应。PI3K/Akt信号通路抑制剂LY294002和激活剂胰岛素能够分别增强和削弱参皂苷Rk3的抗乳腺癌作用及其对PI3K/Akt信号通路的抑制作用，充分的说明人参皂苷Rk3能通过PI3K/Akt信号通路诱导细胞凋亡，抑制肿瘤细胞生长与增殖。. 3．采用乳腺癌裸鼠移植模型在动物整体水平上验证Rk3对抑制肿瘤生长作用。通过HE染色、透射电镜、免疫组化和蛋白免疫印迹法等方法分析肿瘤组织，阐明人参皂苷Rk3能够通过抑制乳腺癌荷瘤裸鼠肿瘤组织中的PI3K/AKT途径导致肿瘤组织caspase蛋白依赖性凋亡。