泛素特異性肽酶22對肝癌細胞凋亡的影響及機制研究

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1.大連市友誼醫院消化內科，遼寧 大連 116000； 2.中山大學附屬第一醫院老年病科； 3.上海交通大學醫學院附屬仁濟醫院重癥醫學科

【Abstract】ObjectiveTo investigate the effect of ubiquitin specific peptidase 22 (USP22) on apoptosis of hepatocellular carcinoma cells and its possible molecular mechanism.MethodsRT-PCR and Western blotting were used to detect the expression of USP22 mRNA and protein in human normal Chang liver cells and human hepatoma HepG2 cells. The USP22 gene was silenced by transfection of USP22-siRNA with liposome, and the silencing effect was detected by RT-PCR and Western blotting. The effects of USP22 gene silencing on HepG2 cell cycle and apoptosis were investigated by flow cytometry, and Western blotting was used to detect the effect of USP22 gene silencing on the expressions of Cleaved caspase-3, Cleaved caspase-9, Cyclin D1 and CDK2 proteins.ResultsThe expression of USP22 gene in human hepatocellular carcinoma HepG2 cells was significantly higher than that in human normal Chang liver cells (P<0.05). After siRNA interference with HepG2 cells, the expressions of USP22 mRNA and protein in the intervention group were significantly lower than those in the control group (P<0.05), but there was no significant difference in the negative group (P>0.05). After the siRNA interfered with HepG2 cells, compared with the control group, the expressions of USP22 mRNA and protein in the intervention group were significantly decreased (P<0.05), but the difference in the negative group was not significant (P>0.05). After silence of the USP22 gene, compared with the control group, the proportion of G0/G1phase cells was significantly increased, the proportions of S phase and G2/M phase cells were decreased significantly, and the rate of apoptosis was increased significantly, whose differences were statistically significant (P<0.05); but there was no significant difference in the percentage of G0/G1phase, phase S and phase G2/M cells and apoptosis rate between the negative group and the control group (P>0.05). Compared with the control group, the relative expressions of Cleaved caspase-3, Cleaved caspase-9, Cyclin D1 and CDK2 proteins in the intervention group were significantly reduced (P<0.05), and the difference between the negative group and the control

group was not significant (P>0.05).ConclusionThe gene silencing of USP22 can induce apoptosis of HepG2 cells in hepatocellular carcinoma, and its mechanism may be related to the decline in expression of cell cycle correlated proteins Cyclin D1, CDK2, and apoptotic proteins Cleaved caspase-3 and Cleaved caspase-9.

【Keywords】 Hepatocellular carcinoma; USP22; Apoptosis; Cell cycle

肝癌是一種常見的發生在肝臟的惡性腫瘤，是人類疾病死亡致死的第二大因素。2015年的統計數據[1-2]顯示，2012年世界上新增肝癌患者約78萬，中國約占其發病率和死亡率的50%。近年來，我國肝癌的發病率和死亡率有明顯上升的趨勢，嚴重影響著人們的健康和生活。研究表明，肝癌的發生與飲水污染、酒精、肝炎病毒、性激素和肝硬化等多種因素密切相關，但肝癌具體的發病機制并不明確，在肝癌的預防和治療方面，我國面臨著很大的挑戰。肝癌的發生、發展是一個十分復雜的過程，研究肝癌細胞的分子機制對肝癌的治療和預防具有重要意義。隨著肝癌研究的不斷深入，尋找抑制細胞生長和細胞凋亡的有效靶點一直是學者們研究的熱點。

泛素特異性肽酶22(ubiquitin specific peptidase 22，USP22)是一種泛素特異性肽酶，在細胞周期、細胞凋亡和信號傳導等生化反應中發揮著重要作用，與多種疾病的發生、發展密切相關。細胞凋亡是一個多階段、多步驟和多基因參與的復雜過程，在肝癌的發生、發展過程中具有重要的負調控作用，研究USP22在肝癌細胞凋亡中分子機制，為肝癌的靶向分子治療提供了新方向。研究[5-7]發現，USP22在甲狀腺癌、肺癌和胃癌等多種腫瘤細胞中呈高表達，與腫瘤的發生發展、惡性程度和預后密切相關。有研究[8]發現，USP22在肝癌中高表達，但其對肝癌的作用機制并不明確。目……