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目的：探讨组蛋白去乙酰化酶抑制剂（HDI）trichostatin A（TSA）对Ku70 的乙酰化及其在TSA诱导结肠癌细胞凋亡中的作用。方法：以TSA 处理结肠癌细胞HCT116 和HT29 细胞，采用免疫沉淀结合Western blot 检测TSA 对Ku70乙酰化的作用，流式细胞术检测TSA诱导的细胞凋亡，Western blot 检测凋亡相关蛋白Bax和细胞色素c（cytochrom c）的转位和表达。结果：TSA 可引起结肠癌HCT116 和HT29 细胞Ku70 乙酰化，并与凋亡密切相关，与对照组相比，HCT116 凋亡率（P=0.007）和HT29 细胞凋亡率（P=0.005）均显著增高，免疫共沉淀检测到TSA处理细胞后，Bax 和Ku70 之间的相互作用减弱，表明TSA 引起的乙酰化促进 Bax 从Bax-Ku70 复合物中释放，Western blot 结果显示TSA促进Bax 由胞浆向线粒体转位，同时促进cytochrom c由线粒体向胞浆转位。结论：Ku70 乙酰化作用介导了TSA 诱导的结肠癌细胞凋亡。

英文摘要:

Objective:To investigate Ku70 acetylation by histone deacetylase inhibitor (HDI) trichostatinA (TSA) and its effect on TSA-induced apoptosis of colorectal cancer cells.Methods:HCT116 and HT29 cells were exposed TSA 1 滋M for 24 h. Immunoprecipitation (IP) and Western blot were used to detect Ku70 acetylation. Apoptosis was analyzed with Annexin V-PI staining by flow cytometry. Co-IP was performed to investigate the interaction between Bax and Ku70. The level of Bax and cytochrome c in cytoplasmand motochondria were detected by Western blot after TSA treatment for 6 h and 18 h.Results:TSA induced Ku70 acetylation in both HCT116 and HT29 cells. TSA also induced apoptosis of HCT116 cells and HT29 cells, with P value of 0.007 and 0.005, respectively. Ku70-induced acetylation was correlated with apoptosis. Co-IP results showed that TSA treatment reduced the interaction between Bax and Ku70, indicating an increase of release of Bax from its association with Ku70 promoted by TSA. Western blot results showed that TSA induced the translocation of Bax from cytoplasm to mitochondria and cytochrome c from mitochondria to cytoplasm.Conclusion:Ku70 acetylation mediates TSA induced apoptosis in colorectal cancer cells.

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