原发性肝细胞癌中p33ING1b与p53基因间协同功能的研究

目的　探讨 p33ING1b与 p5 3基因间的协同功能对肝癌细胞生长、阻滞细胞周期、诱导肿瘤细胞凋亡及对 p5 3下游基因p2 1WAF1/CIP1表达的影响。方法　采用脂质体方法将 p33ING1b与wtp5 3基因分别转染入HepG2、PLC/PRF/ 5和Hep3B 3株内源性p5 3基因表达状态各不相同的肝癌细胞株 ,同时设转染反义 p33ING1b及反义wtp5 3质粒实验组和转染空载体对照组 ,转染 4 8h后检测各实验组细胞凋亡率及分析细胞周期变化 ,用Western印迹杂交分析各实验组肝癌细胞中 p33ING1b与 p5 3蛋白表达的变化 ,通过分析受 p2 1WAF1/CIP1启动子调控的荧光素酶报道基因表达的强弱 ,观察各实验组中p5 3下游基因 p2 1WAF1/CIP1的活性情况。采用 6 %乙醇为诱导剂作用于各实验组后 ,再次观察上述各指标的变化。结果　在表达内源性wtp5 3基因的HepG2细胞中 ,转染入 p33ING1b基因后 ,与对照组相比 ,细胞凋亡率增强 (2 2 5 3% ) ,细胞周期中停滞于G0 /G1期细胞的比例增多 (6 7 4 5 % ) ,下游基因p2 1WAF1/CIP1启动子的活性 (13 0 8)增强 (P <0 0 1)。对于表达突变型p5 3蛋白的PLC/PRF/ 5细胞 ,联合共转染 p33ING1b与wtp5 3实验组的G0 /G1期细胞比例 (78 16 % )及 p2 1WAF1/CIP1启动子活性(12 99)比单转染 p33ING1b或wtp5 3基因实验组高 (P

Study of cooperation of tumor suppressor p33(ING1b) with p53 gene in hepatocellular carcinoma

OBJECTIVE: To investigate the cooperation effect of p33(ING1b), coded protein of the novel tumor-suppressor gene ING1b, with p53 gene on the cell growth, cell cycle arrest, apoptosis and expression of the p53 downstream gene p21(WAF1/CIP1) in hepatocellular carcinoma. METHODS: Recombinant plasmids pcDNA3-INGIb containing sense p33(ING1b) cDNA, and pCMV-wtp53 containing sense p53 gene, and were transfected into HepG2, PLC/PRF/5 and Hep3B hepatoma cell lines with different p53 endogenous expression status using lipofecTAMINE method. Recombinant plasmids pcDNA3-alphaING1b containing antisense p33(ING1b) cDNA, pCMV-alphawtp53 containing antisense p53 gene, and plain vector as control were transfected into the cells. Forty-eight hours after transfection, the apoptosis rates were detected and cell cycle arrest were analyzed by flow cytometry. The expression of p33(ING1b) and wtp53 proteins were detected by Western blot. The luciferase gene reporter plasmid drived by p21(WAF1/CIP1) promoter was also transfected into the cells to analyze the activation of p21(WAF1/CIP1) gene in hepatoma cells. Then 6% ethanol was added into the in DMEM culture medium and all of the above experiments were repeated. RESULTS: After the p33(ING1b) gene was transfected, the apoptosis rate of HepG2 cells which express endogenous wtp53 was enhanced (22.53%), the number of cells arrested in G(0)/G(1) phase was increased (67.45%), and the activation of p21(WAF1/CIP1) promoter reached the highest level (13.08) (all P < 0.01). In the PLC/PRF/5 cells which express endogenous mutant p53, after combined p33(ING1b) and wtp53 gene transfection the percentage of cells arrested in G(0)/G(1) phase (78.16%) and the activation of p21(WAF1/CIP1) promoter (12.99) were higher than those in the experiment groups transfected with p33(ING1b) or wtp53 gene alone (both P < 0.01), however, the difference in apoptosis rate was not statistically significant (P > 0.05). After 6% ethanol treatment, apoptosis rate of PLC/PRF/5 cells transfected with combined p33(ING1b) and wtp53 gene was increased significantly (42.8%). The apoptosis rate and cell cycle arrest were not significantly different between the Hep3B cells with deletion of wtp53 which were transfected with p33(ING1b) and wtp53 gene and those of the control group (P > 0.05), however, the activity of the p21(WAF1/CIP1) promoter was activated in the combined transfectlion group (10.32, P < 0.01). CONCLUSION: p33(ING1b) cooperate with wtp53 in the process of inhibiting hepatoma cell growth, inducing apoptosis, and activating p53 downstream gene p21(WAF1/CIP1), and after chemical inducing reagent treatment the cooperation between p33(ING1b) and wtp53 gene is enhanced.