中文摘要：

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） trichostatin A （TSA） and its effect on TSA-induced apoptosis of colorectal cancer cells. Methods： HCTll6 and HT29 cells were exposed TSA 1 μM 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 cytoplasm and motochondria were detected by Western blot after TSA treatment for 6 h and 18 h. Results： TSA induced Ku70 acetylation in both HCTll6 and HT29 cells. TSA also induced apoptosis of HCTll6 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. Conclusions： Ku70 acetylation mediates TSA induced apoptosis in colorectal cancer cells.