USP9X低表达通过下调Mcl-1促进肝癌细胞凋亡

研究抑制泛素特异性蛋白酶9X（ubiquitin-specific protease 9X,USP9X）对人肝癌（primary hepatocellular carcinoma,HCC）细胞SMMC7721和HepG2中髓细胞白血病-1（myeloid cell leukemia-1,Mcl-1）蛋白的表达调控及对细胞凋亡和生长活力的影响。实验分为USP9X-siRNA组和阴性对照NC组两组进行分析。通过Western blot技术分别检测USP9X在肝癌细胞SMMC7721、HepG2和正常人肝细胞株L02中的蛋白表达情况;应用化学合成USP9X-siRNA转染肝癌细胞SMMC7721和HepG2,通过Western blot、流式细胞仪和MTT检测转染前后Mcl-1的蛋白表达差异以及细胞凋亡和生长活力变化。结果表明,USP9X在肝癌细胞SMMC7721和HepG2中的蛋白表达水平均高于正常肝细胞L02（t=15.155,P=0.000;t=9.171,P=0.001）;SMMC7721和HepG2细胞中抑制USP9X能明显下调Mcl-1的蛋白表达,并导致细胞凋亡增加和生长活力降低。提示,肝癌细胞SMMC7721和HepG2中USP9X表达上调;USP9X表达降低可能通过下调Mcl-1的蛋白表达进而诱导人肝癌细胞SMMC7721和HepG2的凋亡。

Low Expression of USP9X Promoted Apoptosis of Hepatoma Cells Through Mcl-1 Down-regulation

In this paper, we investigated the regulation of inhibiting ubiquitin-specific protease 9X （USP9X） on myeloid cell leukemia-1 （Mcl-1） protein expression and its effect on apoptosis and viability of human hepatocel- lular carcinoma （HCC） cells SMMC7721 and HepG2. There were two groups in the study, USP9X-siRNA group and NC group. The protein expression of USP9X was detected in SMMC7721, HepG2 and normal human liver cell line L02. SMMC7721 and HepG2 cells were infected with USP9X-siRNA, and cell apoptosis and cell growth vi- ability were analyzed by flow cytometry and MTT. Mcl-1, a potential target of USP9X, was detected by Western blot. We found that the protein expressions of USP9X in SMMC7721 and HepG2 were both higher than that in L02 （t= 15.155, P=0.000; t=9.171, P=0.001）. Inhibiting expression of USP9X in SMMC7721 and HepG2 cells obviouslysuppressed Mcl-1 protein expression as well as increased cell apoptosis and decreased cell viability. These results suggested that expression of USP9X was upregulated in hepatoma cells SMMC7721 and HepG2, and inhibiting USP9X might induce cell apoptosis in hepatocellular carcinoma cells SMMC7721 and HepG2 by down-regulating Mcl- 1 protein expression.