乙型肝炎病毒X和p53对肝癌细胞生长的影响

目的　探讨乙型肝炎病毒X(HBx)基因与p5 3在损伤情况下的相互作用及对肝癌细胞生长的影响及作用机制。方法　通过构建正义及反义野生型 (wt)p5 3 ,与HBx分别单转染或共转染含wtp5 3 ( + )、HBV( - )的人肝癌细胞株SMMU 772 1细胞 ,在吡柔比星的诱导下 ,用流式细胞仪检测对细胞凋亡的影响 ,及HBx对细胞周期的影响 ,并通过检测含p5 3结合位点p2 1Waf1启动子荧光素酶活性来观察HBx是否通过p5 3影响p2 1Waf1的表达 ,以及绘制细胞生长曲线观察HBx对SMMU 772 1细胞生长的影响。结果　在吡柔比星的诱导下 ,HBx能够促进细胞凋亡 ,转染空载体组及pcDNA3HBx组细胞凋亡率分别为 5 3 2 %和 12 66%。但HBx对外源性p5 3诱导的细胞的凋亡具有抑制作用 ,转染空载体、正义pcDNA3wtp5 3及正义pcDNA3wtp5 3 +pcDNA3HBx组细胞凋亡率分别为 5 3 2 %、11 72 %、4 67%。同时处在G0 ～G1期瞬时表达及稳定转染HBx细胞数较对照组分别减少 4 79% ,10 2 5 %。而且HBx可抑制p2 1Waf1启动子荧光素酶的活性 (P <0 0 5 )及促进细胞生长。结论　细胞在DNA损伤因素的作用下 ,HBx可能通过抑制p5 3导致p2 1Waf1的表达降低 ,引起停滞在G0 ～G1期的细胞减少 ,导致肿瘤细胞仍能继续分裂增殖形成恶性生长

The role of hepatitis B virus X gene and p53 on hepatocellular carcinoma cell growth

Objective To explore the effects of hepatitis B virus X gene and p53 on hepatocellular growth. Methods Two kinds of plasmids containing sense and antisense human wild p53 gene respectively were constructed. SMMU-7721 cells were transfected with HBx, sense-wtp53 antisense-wtp53 separately or cotransfected with either HBx and sense-wtp53 or HBx and antisense-wtp53. Flow cytometry was adopted to measure the apoptosis rates and the effects of HBx on cell cycle progression. The activity of p21 Waf1 promoter-luciferase construct was detected. Growth curves for SMMU-7721 stably transfected with pcDNA3 and pcDNA3HBx were analyzed. Results After doxorubicin administration, HBx was noticed able to initiate apoptosis of the liver cells. The apoptosis rate was 5.32% in the pcDNA3 transfected and 12.66% in the pcDNA3HBx transfected groups respectively. HBx could also abrogate p53-mediated apoptosis. The apoptosis rate in groups transfected with pcDNA3, pcDNA3wtp53 and pcDNA3HBx+ pcDNA3wtp53 was 5.32%, 11.72% and 4.67% respectively. In compared with the normal group, the number of cells in transiently HBx-expressed group and HBx-transfected group decreased 4.79% and 10.25% respectively. HBx inhibited the activity of p21 Waf1 promoter- luciferase constructed (P<0.05) and promoted cell growth. The growth rate of HBx expression cells was faster. Conclusion Under DNA damage, HBx reduced expression of p21 Waf1 by repressing the activity of p53 protein, followed by disturbing the regulation of G 0-G 1 cell cycle checkpoint, and promoted the growth rate of hepatoma cells.