THE MECHANISMS OF CELL TRANSFORMATION INDUCED BY HEPATITIS CVIRUS

为了揭示丙型肝炎和肝细胞癌与丙型肝炎病毒感染密切相关的分子机制，我们研究了肝细胞来源的产生丙型肝炎病毒蛋白的培养细胞基因表达的变化，并分析了与丙型肝炎病毒基因组及其基因产物相互作用的细胞因子。研究结果如下：1.利用紫外光交联法，在细胞裂解液中发现了一个与丙型肝炎病毒基因组末端片段相互作用的细胞因子。结果表明，该因子为多嘧啶结合蛋白。将特定浓度的瞬时表达载体导入细胞后，获得表达丙型肝炎病毒蛋白的HepG2细胞。以500多个细胞基因片段为靶点，对有和不产生丙型肝炎病毒蛋白的细胞的mRNA样本进行斑点杂交实验。然而，没有发现表达的剧烈变化。我们发现，产生丙型肝炎病毒prot…的浓缩的HepG2细胞更多的EIN对Fas和肿瘤坏死因子(TNF)-α介导的细胞凋亡具有抵抗力，这一功能似乎与丙型肝炎病毒蛋白中的核心蛋白有关。我们发现该核心蛋白通过在某些细胞中协同增强由凋亡信号、抗Fas抗体和肿瘤坏死因子-α诱导的核因子-kappaB的活性而发挥抗凋亡因子的作用。我们还发现，丙型肝炎病毒核心蛋白存在一个非依赖于核因子-kappaB的抗细胞凋亡途径。我们证明了核心蛋白具有与致癌蛋白Ras.6协同转化特定细胞的潜力。研究发现，该核心蛋白可能通过激活MAP激活级联通路来激活细胞增殖。我们认为核心蛋白的抗凋亡作用和转化潜能可能与丙型肝炎病毒的持续感染和肝细胞癌的发生有关，并对核心蛋白这些功能的分子机制进行了进一步的分析。较少

To reveal the molecular mechanisms of hepatitis and hepatocellular carcinoma closely related with the infection of hepatitis C virus (HCV), we investigated the changes of the gene expression in the HCV protein producing cultured cells originated from hepatocytes and analyzed the cellular factor interacting with HCV genome and its gene products. The results are followed ;1. We found a cellular factor interacting with the terminal fragment of HCV genome in the cell lysate by U.V.cross link method. We showed that the factor was the polypyrimidine tract binding protein.2. We obtained HepG2 cells producing a HCV proteins after specific concentration of the transiently plasmid transfected cells. The mRNA samples from the cells with and without HCV protein production were used for dot blothybridization experiment using more than 500 fragments of the cellular genes as targets. However no drastic change of the expression was found.3. We found that the concentrated HepG2 cells producing HCV prot … More eins became resistant against Fas and tumor necrosis factor (TNF)-alpha mediated apoptosis This function was appeared to be responsible to the core protein among a HCV proteins.4. We revealed that the core protein functioned as an anti-apoptotic factor by synergistic enhancement of NF-kappaB activity induced by apoptotic signals, anti Fas antibody and TNF-alpha in certain cells. We also found that there was a NF-kappaB-independent anti-apoptotic pathway by HCV core protein.5. We showed that the core protein have a potential to transform a certain cells cooperatively with an oncogenic protein, Ras.6. The core protein was revealed to have a potential to activate the cell proliferation through the activation of MAP kinase cascade. We consider that the anti-apoptotic effect and transforming potential of the core protein may contribute to the persistent infection of HCV and cause of hepatocellular carcinoma.Further analysis of molecular mechanisms of these functions of the core protein is underway. Less