THE MECHANISMS OF CELL TRANSFORMATION INDUCED BY HEPATITIS CVIRUS

为了揭示与丙型肝炎病毒（HCV）感染密切相关的肝炎和肝细胞癌的分子机制，我们研究了源自肝细胞的HCV蛋白产生细胞的基因表达变化，并分析了与HCV基因组及其基因产物相互作用的细胞因子。结果如下：我们用紫外交联法在细胞裂解液中发现了一个与HCV基因组末端片段相互作用的细胞因子。结果表明，该因子为聚嘧啶束结合蛋白2。在特定浓度的瞬时质粒转染细胞后，我们获得了产生HCV蛋白的HepG2细胞。将HCV蛋白产生和不产生的细胞mRNA样本以500多条细胞基因片段为靶点进行点blothybrization实验。然而，没有发现明显的变化。我们发现浓缩的HepG2细胞产生HCV蛋白，更多的细胞对Fas和肿瘤坏死因子(TNF)- α介导的细胞凋亡具有抗性，这种功能似乎与HCV蛋白中的核心蛋白有关。我们发现，在某些细胞中，核心蛋白通过凋亡信号、抗Fas抗体和tnf - α诱导的NF-kappaB活性协同增强而发挥抗凋亡因子的作用。我们还发现HCV核心蛋白存在一个不依赖nf - kappab的抗凋亡通路。我们发现核心蛋白具有与致癌蛋白ras协同转化特定细胞的潜力。该核心蛋白通过激活MAP激酶级联，具有激活细胞增殖的潜力。我们认为核心蛋白的抗凋亡作用和转化潜力可能是HCV持续感染和肝细胞癌发生的原因之一。对核心蛋白这些功能的分子机制的进一步分析正在进行中。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