蛋白激酶C在表没食子儿茶素没食子酸酯诱导LoVo细胞凋亡中的作用

目的　探讨蛋白激酶C在表没食子儿茶素没食子酸酯 (EGCG)诱导大肠癌LoVo细胞凋亡中的调控作用。方法　在有或没有蛋白激酶C激活剂PMA预处理LoVo细胞的情况下 ,用流式细胞术、Westernblot分析以及蛋白激酶C检测试剂盒检测EGCG处理LoVo细胞前后其细胞内多种蛋白激酶C同工酶表达水平和细胞内蛋白激酶C总活性的变化。结果　PMA(10 0nmol·L-1)预处理LoVo细胞 3h ,可部分地抑制EGCG诱导的LoVo细胞凋亡。流式细胞术和Westernblot分析显示EGCG处理LoVo细胞后可引起该细胞内多种蛋白激酶C同工酶包括cPKCα、βⅠ、βⅡ、nPKCε和aPKCξ表达水平下调 ,并呈时间效应关系 ;而细胞内蛋白激酶C总活性无明显变化。结论　蛋白激酶C参与了EGCG诱导LoVo细胞凋亡的调控作用 ,主要是通过下调多种蛋白激酶C同工酶表达水平而不是通过影响细胞内蛋白激酶C总活性而发挥作用

Effects of PKC on (-) epigallocatechin 3 gallate mediated apoptosis in LoVo cells

AIM To investigate the regulatoin of PKC in (-) epigallocatechin 3 gallate(EGCG) induced apoptosis in human colon carcinoma LoVo cells. METHODS The expression level of a few PKC isozymes were determined by flow cytometry and Western blot analysis, respectively. The cellular total activities of PKC were detected by PKC activity assay kit after treatment of LoVo cells with EGCG, in the presence or absence of preteatment of LoVo cells with phorbol 12 myristate 13 acetate (PMA), a potent PKC stimulator. RESULTS EGCG induced apoptosis in LoVo cells was in part inhibited by the pretreatment with 100 nmol·L -1 PMA for 3 hours. Treatment of LoVo cells with EGCG downregulated the expression level of a few protein kinase C isozymes including cPKCα, βⅠ, βⅡ, nPKCε, and aPKCξ in a time dependent manner. However, there were no obvious alterations of the cellular total activities of PKC. CONCLUSION PKC participates in the regulatory effects on EGCG induced apoptosis in LoVo cells, which is mainly mediated by EGCG induced downregulation of the expression level of a few protein kinase C isozymes rather than the cellular total activities of PKC.