Why does the tea extract occur a cell death for tumor cells but not Normal cells?

为什么茶提取物可以使肿瘤细胞死亡，而不能使正常细胞死亡？

基本信息

批准号：
13660133
负责人：
YUASA Isao
金额：
$ 2.24万
依托单位：
Osaka City University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13660133/
关键词：
Green tea extract Apoptosis intracellular active oxygen tumor cells cell proliferation tumor angiogenesis signal transduction antioxidative enzymes 抗酸化酵素系血管内皮増殖因子 MAPキナーゼ ASK-1 チオレドキシン茶ポリフェノールグルタチオン細胞周期カスパーゼ Rbタンパク

项目摘要

Green tea has shown to be active chemopreventive agents against cancer both in vivo and in vitro studies. However, the complete mechanisms underlying the inhibitory effects are not fully understood. In most of our studies, the green tea extract (GTE) and its galloyl polyphenols, epigallocatechin (EGC), have shown tumor growth inhibitory effects in Ehrlich ascites tumor cells and several mechanisms have been elucidated. Notable among these include decrease in ornithine decarboxylase activity and in cellular glutathione (GSH) and protein SH levels, cellular thiol-dependent induction of mitogen activated protein kinases including JNK-SAPK, p38 and ERK1/2 and changes in mitochondrial integrity involving cytochrome c release, and subsequent activation of caspase-3-like protease. We also observed that cells incubated with EGG resulted in an accumulation of a discrete sub-population of signals under the sub-Gi and Gi cell cycle regions and a decrease in S cell cycle region. Futermore, EGG dec … More reased hypophosphorylated retinoblastoma protein (Rb) levels in a dose-dependent and time-dependent manner. The effect of Rb phosphorylation decreased by EGG was abolished with N-ace tylcysteine, suggesting that reactive oxygen speaces (ROS) involves in the green tea extract-induced apoptosis. ROS has been observed to take part in highly organized cellular functions like pathways of signal transduction and apoptosis. We observed that Ehrlich ascites tumor cells exposed to EGG increased in intracellular peroxide 30-60 mm after incubation with EGG as compared with non-treated cells. The decrease in cell viability with EGG was improved with the addition of catalase or NAC. GTE caused the dissociation of thioredoxin from ASK1. The dissociation was abolished with the addition of NAC or catalase. In tumor cells but not normal cells, the activities of enzymes scavenging active oxygen, SOD, glutathione peroxidase and catalase, are very low. Therefore, ROS, which are induced with addition of green tea extract, took part in highly organized cellular functions like pathways of signal transduction and apoptosis.Furthermore we found that the decrease of the expression of Flt-1 and KDR/Flk-1 in Human umbilical vein endothelial cells by green tea extract was detected with immunohistoehemical and Western blotting methods. These results suggest that green tea extract may have preventive effects on tumor angiogenesis and metastatis through reduction of expression of VEGF receptors. Less

在我们的大多数研究中，绿茶对癌症的抑制作用均不完全了解。细胞谷胱甘肽（GSH）和蛋白质SH水平丝分裂蛋白激活的蛋白激酶墨水墨水，p38和ERK1/2 Mitchondrial完整性完整性完整性细胞Crelease ub secteration ub secteration ub secteration ub secteration ub caspase-3类似蛋白酶的激活。在亚GI和CELLE循环大陆上的离散亚访问的积累，S细胞周期区域的减少。通过N-ace tylcyseine诱导的细胞凋亡，卵子诱导的蛋白质细胞中的肿瘤细胞在细胞内30-60 ITH卵中增加了蛋白质的细胞凋亡。鸡蛋是添加过氧化氢酶或NAC GTE引起的，从而添加了NAC或CETALASE的分解。通过绿茶提取物，用ITH含量和蛋白质印迹方法对肿瘤血管生成和Metastatis摇摇欲坠的表达降低。