表没食子儿茶素没食子酸酯下调胃癌细胞血管内皮生长因子表达的分子机制研究  

（-）-Epigallocatechin-3-gallate reduces vascular endothelial growth factor expression in gastric cancer cells via suppressing activity

作　　者：朱宝和[1] 何裕隆[1] 詹文华[1] 蔡世荣[1] 王昭[1] 张常华[1] 陈华云[1] 

机构地区：[1]中山大学附属第一医院胃肠胰外科,广州510080

出　　处：《中华胃肠外科杂志》2011年第8期631-635,共5页Chinese Journal of Gastrointestinal Surgery

基　　金：基金项目：国家自然科学基金（30571833）;广东省自然科学基金（05001785）;中国博士后基金（20100470963）

摘　　要：目的探讨表没食子儿茶素没食子酸酯（EGCG）通过抑制转录活化因子（Stat3）活性下调胃癌细胞血管内皮生长因子（VEGF）表达的分子机制。方法采用Westernblot法检测AGS胃癌细胞分别在50μg／L IL-6加0、5、10、25、50μmol／LEGCG作用下，VEGF、总Stat3（tStat3）和活化Stat3（pStat3）的表达情况：检测Stat3信号通路抑制剂对IL-6诱导的VEGF蛋白表达水平的影响。酶联免疫吸附法检测肿瘤细胞培养液中VEGF蛋白水平。RT-PCR法检测胃癌细胞VEGFmRNA表达水平。制备细胞核提取液，WestemMot法检测肿瘤细胞核内pStat3表达；同时采用染色体免疫沉淀方法检测Stat3与DNA的结合活性。结果IL-6可以诱导AGS胃癌细胞VEGF表达．与未添加组比较，添加IL．6组胃癌细胞VEGF蛋白表达、分泌和mRNA表达分别增加了2．4、2．8和3．1倍（均P〈O．01）：EGCG剂量依赖性地抑制IL-6诱导的胃癌细胞VEGF蛋白表达、分泌和VEGFmRNA表达（P〈0．05）。EGCG和Stat3信号通路抑制剂AG490可以显著抑制IL-6诱导的VEGF表达（P〈0．01）：EGCG处理的胃癌细胞中IL-6诱导的pStat3表达剂量依赖性地减少（P〈O．05），但EGCG不影响IL-6诱导的tStat3表达（P〉0．05）；同时，EGCG可以直接抑制胃癌细胞自身和IL-6诱导的Stat3核转位和Stat3-DNA结合活性（P〈0．05）。结论EGCG通过抑制Stat3活性．从而下调胃癌细胞VEGF表达。Objective To investigate the molecular mechanism involved in the downregulation of vascular endothelial growth factor（VEGF） expression through the suppression of signal transducer and activator of transcription 3 （Stat3） by （-）-Epigallocateehin-3-gallate （EGCG）. Methods After human gastric cancer cells （AGS） were treated with IL-6 （50 μg/L） and EGCG（O, 5, 10, 25 or 50 μmol/L）, the expression levels of VEGF, total Stat3 （tStat3）, and activated Stat3 （pStat3） in tumor cells were examined by Western blotting. The influence of the inhibitor of Star3 pathway on the IL-6-induced VEGF expression was investigated. VEGF protein level in tumor cell culture medium was determined by ELISA and VEGF mRNA expression in tumor cells by RT-PCR. Tumor cell nuclear extract was prepared and nuclear expression of pStat3 was detected. Stat3-DNA binding activity was examined with chromatin immunoprecipitation（ChIP） assay. Results IL-6 significantly increased VEGF expression in AGS gastric cancer cells. Compared with the group without IL-6, the expression and secretion of VEGF protein, and mRNA expression increased by 2.4 fold, 2.8 fold, and 3.1 fold（all P〈0.01 ）, respectively. EGCG treatment markedly reduced VEGF protein, release and mRNA expression in a dose-dependent manner. When compared with the control group induced by IL-6, EGCG and AG490 （a Stat3 pathway inhibitor） significantly inhibited VEGF expression induced by IL-6 （P〈0.01）. EGCG dose-dependently inhibited pStat3 induced by IL-6 （P〈0.05）, but not tStat3 （P〉0.05）. Stat3 nuclear translocation and Stat3-DNA binding activity in AGS cells or that induced by IL-6 were directly inhibited by EGCG （P〈 0.05）. Conclusion EGCG reduces expression of VEGF in gastric cancer cells through the inhibition of Stat3 activity.

关 键 词：表没食子儿茶素没食子酸酯 血管生成 血管内皮生长因子 转录活化因子 胃肿瘤 

分 类 号：R735.2[医药卫生—肿瘤]