Modification of Cell Growth Regulation by Hepatitis C virus

丙型肝炎病毒(丙型肝炎病毒)持续感染，导致慢性肝炎、肝硬变和肝细胞癌。为了应对持续感染的影响，建立了丙型肝炎病毒全基因组在人肝细胞中的条件表达系统。丙型肝炎病毒表达后，细胞DNA合成受到抑制，细胞生长主要受阻于G0/G1期，这主要是通过非细胞凋亡途径实现的。传代48天后，细胞生长已恢复到初始水平。为了阐明丙型肝炎病毒的靶标，我们检测了生长调节因子的表达水平。丙型肝炎病毒对细胞生长的影响与p21WAF1/CIP1的表达有关，传代48d后，Rb蛋白过度磷酸化。丙型肝炎病毒对p21WAF1/CIP1的这种修饰是在转录水平上以非依赖于p53的方式引起的。因此，丙型肝炎病毒可以通过p21WA1/CIP1改变细胞周期检查点，加速肝细胞的致癌性。体内丙型肝炎病毒的作用也表现在转基因小鼠模型上。丙型肝炎病毒的表达使肝细胞对Fas介导的细胞凋亡具有更强的抵抗力。通过体外和体内表达模型，进一步揭示了丙型肝炎病毒致病的分子机制。

Hepatitis C virus (HCV) infects persistently and causes chronic hepatitis, liver cirrhosis and hepatocellular carcinoma (HCC). To address the effect of persistent infection, the conditional expression system of full-genome HCV in human liver cells was established. Following HCV expression, DNA synthesis of cells was suppressed, cell growth was mainly retarded at G0/G1 phase through apoptosis independent pathway. However, after 48 days passage, cell growth has been recovered to be initial level. In order to clarify the target of HCV, we examined the expression level of growth regulators. The cell growth modification by HCV correlated to the extent of p21WAF1/CIP1 expression and hyperphosphorylation of Rb was induced after 48 days passage. This modification of p21WAF1/CIP1 by HCV was caused at transcriptional level in the p53 independent manner. Thus, HCV could modify the cell cycle checkpoint to accelerate the tomurigenicity of hepatocyte through p21WA1/CIP1.The effect of HCV in vivo was also characterized with HCV-transgenic mice model. Expression of HCV made hepatocytes more resistant to Fas-mediated apoptosis. By using in vitro and in vivo HCV expression model, we further characterized the molecular mechanism of pathogenesis of HCV.