胰腺癌细胞凋亡伴随胱天蛋白酶依赖性BAG3蛋白剪切的研究

Caspase-dependent cleavage of BAG3 associated with pancreatic cancer cell apoptosis

目的:前期研究表明,蛋白酶体抑制剂诱导甲状腺癌细胞凋亡时伴随抗凋亡蛋白BAG3的剪切。本研究探讨BAG3蛋白剪切是否为细胞凋亡伴随的普遍现象。方法:选取人胰腺癌细胞SW1990和PANC1,分别设培养液处理空白对照组、蛋白酶体抑制剂MG132单独或与z-VAD联合处理组、星形孢菌素(STS)单独或与z-VAD联合处理组、依托泊苷单独或与z-VAD联合处理组、TNFα单独或与z-VAD联合处理组以及紫外线单独照射或与z-VAD联合处理组;利用蛋白质印迹法检测各组细胞中BAG3蛋白的剪切情况;利用流式细胞仪(FCM)检测细胞凋亡率。结果:与甲状腺癌细胞类似,蛋白酶体抑制剂MG132诱导胰腺癌细胞凋亡的同时,伴随BAG3蛋白的剪切;其他凋亡诱导剂如依托泊苷、星形孢菌素和紫外线照射在诱导胰腺癌细胞凋亡的同时,也可诱导BAG3蛋白剪切体的出现;而广谱胱天蛋白酶抑制剂z-VAD可以完全抑制BAG3蛋白的剪切。结论:胱天蛋白酶依赖性BAG3蛋白的剪切可能是细胞凋亡时的普遍现象,BAG3可能为胱天蛋白酶作用底物。

OBJECTIVE：We have previously reported that BAG3 was cleaved when thyroid cancer cell apoptosis was induced by proteasome inhibitors.In this study,we investigate that whether cleavage of BAG3 is a general phenomenon associated with cell apoptosis.METHODS： Pancreatic cancer cells SW1990 and PANC1 were treated with vehicle,proteasome inhibitor MG132 alone or combination with z-VAD,etoposide alone or combination with z-VAD,staurosporine alone or combination with z-VAD,UV irradiation alone or combination with z-VAD,TNFα alone or combination with z-VAD.Cleavage of BAG3 was analyzed using Western blot,and apoptotic rate was analyzed using flow cytometry（FCM）.RESULTS：Similar like in thyroid cancer cells,MG132 induced apoptosis associated with cleavage of BAG3 in pancreatic cancer SW1990 and PANC1 cells and so did staurosporine,etoposide,TNFα and UV irradiation.Pan-caspase inhibitor z-VAD completely blocked the occurrence of BAG3 cleavage.CONCLUSION： Caspase-dependent cleavage of BAG3 may be a general phenomenon associated with cell apoptosis.