Epigallocatechin-3-gallate-induced stress signals in HT-29 human colon adenocarcinoma cells
Epigallocatechin-3-gallate-induced stress signals in HT-29 human colon adenocarcinoma cells
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DOI：
10.1093/carcin/bgg091
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发表时间：
2003-08-01
期刊：
影响因子：
4.7
通讯作者：
Kong, ANT
中科院分区：
文献类型：
--
作者：
Chen, C;Shen, GX;Kong, ANT
表没食子儿茶素没食子酸酯（Epigallocatechin-3-gallate，EGCG）是绿色茶多酚的主要成分，在动物模型和流行病学研究中已被证明具有抑制结肠肿瘤发生的作用。由于口服给药后EGCG保留在胃肠道中，这种药代动力学特性使其具有作为结肠癌化学预防剂的潜力。在这项研究中，人大肠癌HT-29细胞与表没食子儿茶素没食子酸酯（EGCG）的抗增殖和促凋亡作用，以及这些作用的分子机制进行了研究。采用细胞活力测定、细胞核染色、DNA片段化、半胱天冬酶测定、细胞色素c释放、DiOC（6）（3）染色、丝裂原活化蛋白激酶（MAPK）磷酸化和台盼蓝拒染法等方法分析EGCG诱导的细胞凋亡信号通路。处理36小时后，EGCG抑制HT-29细胞生长，IC 50接近100 μ M。HT-29细胞用高于100 μ M的剂量处理显示明显的核浓缩和碎片化，这被DNA梯状化证实。处理12 h后检测到Caspase-3和-9活化，伴随线粒体跨膜电位转换和细胞色素c释放。MAPK的激活被检测为由EGCG引起的早期信号事件。c-Jun N末端激酶（JNK）途径的抑制表明JNK参与了EGCG诱导的细胞色素c释放和细胞死亡。抗氧化剂谷胱甘肽和N-乙酰-L-半胱氨酸阻断了EGCG诱导的JNK激活，表明细胞死亡信号可能是由氧化应激引发的。总之，我们的研究结果表明，在HT-29人结肠癌细胞中，（i）EGCG处理导致线粒体损伤，（ii）JNK介导了EGCG诱导的细胞凋亡。
Epigallocatechin-3-gallate (EGCG), a major component in green tea polyphenols, has been proven to suppress colonic tumorigenesis in animal models and epidemiological studies. As EGCG is retained in the gastrointestinal tract after oral administration, this pharmacokinetics property gives it the potential to function as a chemopreventive agent against colon cancer. In this study, human colorectal carcinoma HT-29 cells were treated with EGCG to examine the anti-proliferative and pro-apoptotic effects of EGCG, as well as the molecular mechanism underlying these effects. Cell viability assay, nuclear staining, DNA fragmentation, caspase assay, cytochrome c release, DiOC(6)(3) staining, mitogen-activated protein kinases (MAPK) phosphorylation and trypan blue exclusion assays, were utilized to dissect the signaling pathways induced by EGCG. After 36 h treatment, EGCG inhibited HT-29 cell growth with an IC50 of similar to100 muM. HT-29 cells treated with doses higher than 100 muM showed apparent nuclear condensation and fragmentation, which was confirmed by DNA laddering. Caspase-3 and -9 activation was detected after 12 h treatment, accompanied by mitochondrial transmembrane potential transition and cytochrome c release. Activation of MAPKs was detected as early signaling event elicited by EGCG. Inhibition of c-Jun N-terminal kinase (JNK) pathway showed the involvement of JNK in EGCG-induced cytochrome c release and cell death. EGCG-induced JNK activation was blocked by the antioxidants glutathione and N-acetyl-l-cysteine, suggesting that the cell death signaling was potentially triggered by oxidative stress. In summary, our results from this study suggest that in HT-29 human colon cancer cells (i) EGCG treatment causes damage to mitochondria, and (ii) JNK mediates EGCG-induced apoptotic cell death.