Zhang Yin, Xu Yu-Ying, Sun Wen-Jie, Zhang Mo-Han, Zheng Yi-Fan, Shen Han-Ming, Yang Jun, Zhu Xin-Qiang
Department of Toxicology, Zhejiang University School of Public Health, Hangzhou, Zhejiang 310058, China.
Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597.
Biomed Res Int. 2016;2016:5013409. doi: 10.1155/2016/5013409. Epub 2016 Oct 18.
Previously we have shown that (-)-epigallocatechin gallate (EGCG) can induce nonapoptotic cell death in human hepatoma HepG cells only under serum-free condition. However, the underlying mechanism for serum in determining the cell fate remains to be answered. The effects of fetal bovine serum (FBS) and its major component bovine serum albumin (BSA) on EGCG-induced cell death were investigated in this study. It was found that BSA, just like FBS, can protect cells from EGCG-induced cell death in a dose-dependent manner. Detailed analysis revealed that both FBS and BSA inhibited generation of ROS to protect against toxicity of EGCG. Furthermore, EGCG was shown to bind to certain cellular proteins including caspase-3, PARP, and -tubulin, but not LC3 nor -actin, which formed EGCG-protein complexes that were inseparable by SDS-gel. On the other hand, addition of FBS or BSA to culture medium can block the binding of EGCG to these proteins. docking analysis results suggested that BSA had a stronger affinity to EGCG than the other proteins. Taken together, these data indicated that the protective effect of FBS and BSA against EGCG-induced cell death could be due to (1) the decreased generation of ROS and (2) the competitive binding of BSA to EGCG.
此前我们已经表明，（-）-表没食子儿茶素没食子酸酯（EGCG）仅在无血清条件下才能诱导人肝癌HepG细胞发生非凋亡性细胞死亡。然而，血清在决定细胞命运方面的潜在机制仍有待解答。本研究调查了胎牛血清（FBS）及其主要成分牛血清白蛋白（BSA）对EGCG诱导的细胞死亡的影响。结果发现，BSA与FBS一样，能够以剂量依赖的方式保护细胞免受EGCG诱导的细胞死亡。详细分析表明，FBS和BSA均能抑制活性氧的产生，从而抵御EGCG的毒性。此外，EGCG被证明能与某些细胞蛋白结合，包括半胱天冬酶-3、聚（ADP-核糖）聚合酶和微管蛋白，但不与LC3或肌动蛋白结合，这些结合形成了SDS凝胶无法分离的EGCG-蛋白质复合物。另一方面，向培养基中添加FBS或BSA可阻断EGCG与这些蛋白质的结合。对接分析结果表明，BSA对EGCG的亲和力比其他蛋白质更强。综上所述，这些数据表明，FBS和BSA对EGCG诱导的细胞死亡的保护作用可能归因于：（1）活性氧产生减少；（2）BSA与EGCG的竞争性结合。
