不同肿瘤细胞对表没食子儿茶素没食子酸酯细胞毒敏感性的差异及其机制

Difference of Susceptivity in Different Tumor Cells to (-)-Epigallocatechin-3-Gallate-Mediated Cytotoxicity and its Possible Molecular Mechanism

目的 探讨表没食子儿茶素没食子酸酯 (EGCG )对大肠癌LoVo细胞、胃癌MGC 80 3细胞和肝癌BEL 740 2细胞细胞毒作用 ,及其作用的差异性和可能的分子机制。方法 在有或无谷胱甘肽合成酶抑制剂DL buthionine [S ,R ] sulfoximine(BSO )预处理的情况下 ,采用MTT法和台盼蓝拒染法测定EGCG对 3株肿瘤细胞的细胞毒作用。采用紫外分光光度法和流式细胞术分别测定经BSO处理的 3株肿瘤细胞的细胞内谷胱甘肽含量和bcl 2蛋白表达水平的变化。结果 EGCG对 3株肿瘤细胞均有细胞毒作用 ,但作用的强弱有所不同 ,其中LoVo细胞较为敏感 ,MGC 80 3细胞次之 ,而BEL 740 2细胞的敏感性最差。他们的IC5 0值分别为 12 5 .30 μg/ml、188.5 2 μg/ml和 2 6 4.5 3μg/ml。用BSO降低这些肿瘤细胞内谷胱甘肽的含量 ,可明显地增强EGCG对 3株肿瘤细胞细胞毒作用的敏感性。BSO以时间依赖的方式下调MGC 80 3和BEL 740 2细胞中bcl 2蛋白表达水平。结论 EGCG对 3株肿瘤细胞细胞毒作用的差异性与细胞内谷胱甘肽含量有关 ,谷胱甘肽和bcl 2蛋白的相互作用可能是这种差异性的分子机制。

Objective To investigate (-)-epigallocatechin-3-gallate (EGCG)-mediated cytotoxicity to colon carcinoma LoVo cells,gastric carcinoma MGC-803 cells and hepatic carcinoma BEL-7402 cells,difference in the cytotoxicity,and its possible molecular mechanism.Methods In the presence or absence of pretreatment with DL-buthionine-[S,R]-sulfoximine(BSO),a glutathione synthesis enzyme inhibitor,the cytotoxcity of EGCG to LoVo cells,MGC-803 cells and BEL-7402 cells were tested by tetrazolium salt MTT assay and trypan blue exclusion.The changes of GSH content and expression of bcl-2 protein were determined by ultraviolet spectrophotography and flow cytometry after treatment of the cells with BSO.Results EGCG had the cytotoxicity to LoVo cells,MGC-803 cells and BEL-7402 cells,but there was difference in the extent of cytotoxicity,of which LoVo cells was the most susceptive to EGCG,MGC-803 was the next,and BEL-7402 was the least.Their IC50 value was 125.30,188.52 and 264.53 μg/ml,respectively.Pretreatment of the three tumor cells with BSO,resulting in a decrease in intracellular GSH content in time-dependent manner,markedly enhanced the susceptivity of the tumor cells to EGCG,and down-regulated the expression level of bcl-2 protein in MGC-803 cells and BEL-7402 cells with time-dependence.Conclusion The difference in cytotoxicity of EGCG to the three tumor cells is associated with intracellular glutathione content.Interaction with intracellular glutathione and bcl-2 protein is possible molecular mechanism.