Green tea polyphenols induce cell death in breast cancer MCF-7 cells through induction of cell cycle arrest and mitochondrial-mediated apoptosis

Abstract

In order to study the molecular mechanisms of green tea polyphenols (GTPs) in treatment or prevention of breast cancer, the cytotoxic effects of GTPs on five human cell lines (MCF-7, A549, Hela, PC3, and HepG2 cells) were determined and the antitumor mechanisms of GTPs in MCF-7 cells were analyzed. The results showed that GTPs exhibited a broad spectrum of inhibition against the detected cancer cell lines, particularly the MCF-7 cells. Studies on the mechanisms revealed that the main modes of cell death induced by GTPs were cell cycle arrest and mitochondrialmediated apoptosis. Flow cytometric analysis showed that GTPs mediated cell cycle arrest at both G1/M and G2/M transitions. GTP dose dependently led to apoptosis of MCF-7 cells via the mitochondrial pathways, as evidenced by induction of chromatin condensation, reduction of mitochondrial membrane potential (ΔΨm), improvement in the generation of reactive oxygen species (ROS), induction of DNA fragmentation, and activations of caspase-3 and caspase-9 in the present paper.

摘要

目的

评估茶多酚对人乳腺癌细胞MCF-7 凋亡的影响, 并探讨了其作用机制。

创新点

全面考察了茶多酚对抗乳腺癌的分子机制,为茶 多酚作为抗肿瘤辅助药物提供理论依据。

方法

首先选取不同组织来源的五种人肿瘤细胞(人肝 癌细胞HepG2、人肺癌细胞A549、人前列腺癌 细胞PC3、人宫颈癌细胞Hela、人乳腺癌细胞 MCF-7)作为体外模型,以MTT 法检测茶多酚 对其增殖抑制作用。然后,选用最敏感细胞 MCF-7 为研究对象,采用流式细胞术检测茶多酚 对细胞周期分布的影响,用Hoechst 3328 染色法 观察茶多酚对细胞核形态的影响,用JC-1 染色法 观察茶多酚对细胞线粒体跨膜电位的影响,用双 氯荧光素(DCFH-DA)染色法观察茶多酚对细 胞活性氧(ROS)水平的影响,用凝胶电泳DNA 片段测定法(DNA ladder)观察茶多酚处理后细 胞DNA 断裂情况,用蛋白质印迹法(Western blot)检测茶多酚对细胞凋亡关键蛋白caspase-3 和caspase-9 表达的影响,全面探讨了茶多酚体外 抗肿瘤机制。

结论

实验结果显示,茶多酚能够通过诱导细胞周期阻 滞和线粒体凋亡抑制MCF-7 细胞增殖。茶多酚诱 导线粒体凋亡的途径是使线粒体跨膜电位下降, 促使MCF-7 细胞内ROS 生成,促使细胞DNA 断裂和促进细胞内caspase-3 和caspase-9 的活化。