Bcl-2家族蛋白在维生素E琥珀酸酯诱导人胃癌细胞凋亡中的作用

目的:研究Bcl-2家族蛋白在维生素E琥珀酸酯(RRR-α-tocopheryl succinate,α-TOS;vitamin E succinate,VES)诱导人胃癌SGC-7901细胞凋亡线粒体途径中的作用。方法:采用噻唑蓝(MTT)法测定VES对SGC-7901细胞的半数抑制浓度(IC50值);吖啶橙/溴化乙啶(AO/EB)染色观察细胞凋亡;Mito Tracker Red CMXRos染色观察线粒体膜电位(ΔΨm)的改变;Western Blot法检测不同剂量VES对人胃癌SGC-7901细胞Bid、Bax、Bcl-2蛋白表达和细胞色素C(cytochrome C,Cyt C)蛋白表达与定位的影响。结果:VES对SGC-7901细胞的IC50值为101.45μg/ml;VES可引起SGC-7901细胞发生凋亡和线粒体膜电位下降;并引起Cyt C蛋白在细胞内重新定位、Bid蛋白剪切活化、Bax蛋白表达增加和Bcl-2蛋白表达减少。结论:VES可抑制SGC-7901细胞的生长,并通过线粒体途径诱导凋亡,其机制可能是通过剪切活化Bid蛋白、上调Bax/Bcl-2相对水平来实现的。

THE ROLE OF BCL-2 FAMILY PROTEIN IN VITAMIN E SUCCINATE INDUCED APOPTOSIS OF HUMAN GASTRIC CANCER CELL LINES

Objective: To study roles of mitochondria and Bcl-2 family proteins in vitamin E succinate-induced apoptosis of human gastric carcinoma SGC-7901 cells.Method: The inhibitory concentration 50%(IC50) of VES in SGC-7901 cell apoptosis was observed by MTT.Fluorescent staining was used to detect apoptosis and the changes of mitochondrial transmembrane potential(ΔΨm) of the cells.The expressions of Bid,Bax,Bcl-2 and cytochrome C proteins were measured by Western blot after the cells were treated with VES at doses of 5,10,20μg/ml respectively.The redistribution of cytochrome C between the mitochondrial and the cytosolic fractions was observed by Western blot after the cells were treated with 20μg/ml VES for 24h.Results: The IC50 of VES in SGC-7901 cells was 101.45 μg/ml.VES caused apoptosis and the loss of mitochondrial transmembrane potential(ΔΨm).Western blot analysis demonstrated that the levels of cytochrome C in four different groups were similar.After the cells were treated with 20μg/ml VES for 24h,cytochrome C was released from mitochondria to cytosol.The expression of Bid in the four groups were similar,but Bid was cleaved into its active form tBid in 10μg/ml and 20 μg/ml group.The expression of Bax in the cells was markedly increased and Bcl-2 decreased,which resulted in the increase of the ratio of Bax/Bcl-2.Conclusion: VES can induce apoptosis of SGC-7901 cells through mitochondrion pathway by activating Bid and up-regulating Bax/Bcl-2.