蛋白酶体抑制剂通过Bcl-2相关抗凋亡蛋白3剪切诱导乳腺癌MCF-7细胞凋亡

Proteasome Inhibitor Induced Apoptosis in MCF-7 Breast Cancer Cells Through Cleavage of BAG3 Protein

[目的]探讨蛋白酶体抑制剂诱导乳腺癌MCF-7细胞凋亡与BAG3蛋白剪切的相互关系,以及BAG3蛋白剪切是否依赖胱天蛋白酶介导完成。[方法]选取人MCF-7乳腺癌细胞系,设空白对照组、MG132处理组、Z-VAD处理组和MG132+Z-VAD联合组。实时定量RT-PCR和Western Blot分别检测各组细胞中BAG3 mRNA和蛋白的表达水平;流式细胞仪检测细胞凋亡。[结果]MG132诱导乳腺癌细胞凋亡过程中BAG3基因和蛋白表达均增高(P<0.05),但BAG3蛋白剪切体也随之增加,流式细胞术结果证明细胞凋亡率增高(P<0.05)。同时,应用胱天蛋白酶体抑制剂Z-VAD处理细胞后,BAG3蛋白剪切体消失。[结论]蛋白酶体抑制剂可诱导上调乳腺癌MCF-7细胞中BAG3基因和蛋白的表达,但BAG3蛋白裂解增强,可导致细胞凋亡增加,这一效应可能依赖胱天蛋白酶介导完成。

[Purpose] To investigate the role of BAG3 in proteasome inhibitor mediated apopto- sis in breast cancer MCF-7 cells and whether BAG3 was cleaved in a caspase-dependent man- ner. [Methods] MCF-7 cell was cultured and treated with vehicle,MG132,pancaspase inhibitor Z-VAD or combination of Z-VAD and MG132. BAG3 mRNA and protein levels were analyzed by RT-PCR and Western Blot respectively.Flow cytometry （FCM） was used to determine the apoptotic rate of cells. [ Results ] Western Blot and Real-time PCR showed that both mRNA and protein expressions of BAG3 in the cells increased by MG132 treatment （P〈0.05） and cleavage product of BAG3 was also induced by MG132,accompanied with increasing apoptosis rate （P〈 0.05）. Cleavage of BAG3 was inhibited by caspase inhibitor Z-VAD. [Conclusion] Proteasome inhibitor could induce the up-regulation of BAG3 mRNA and protein in MCF-7 cells,but the enhanced proteolytic cleavage of BAG3 could be contribute to increasement of apgptosis,whose process might be mediated in a caspase-dependent manner. Subject words： caspase; Bcl-2-associated athanogene 3 ; proteasome inhibitor; breast neoplasms