Virus-gene interactions during hepatic carcinogenesis

描述(申请人提供)：肝细胞癌是全球癌症相关死亡的主要原因之一。肝细胞癌是一种由遗传因素和环境因素共同作用诱发的恶性肿瘤。在环境因素中，乙肝病毒或丙型肝炎病毒感染是主要的危险因素。最近的分子和遗传学研究表明，通过解除对肝细胞增殖、分化和凋亡至关重要的信号通路的调控，乙肝病毒和丙型肝炎病毒蛋白在肝细胞癌的发病过程中具有直接作用。15然而，从乙肝病毒或丙型肝炎转基因小鼠的长潜伏期和低发病率研究表明，在这些受损的肝细胞中存在额外的基因突变，这是恶性转化和肝细胞癌形成所必需的。该提案的目的是描述肝癌发生过程中病毒与基因的相互作用。我们假设，特定的遗传事件，如c-Myc或c-Met的过度表达，β-catenin激活突变，以及肿瘤抑制基因TP53的丢失，将加速乙肝或丙型肝炎核心转基因小鼠的肝癌发展。为了检验这一假设，我们提出了两个具体目标。在第一个目标中，我们将确定在乙肝转基因小鼠中诱发肝癌的基因改变(S)；在第二个目标中，我们将确定在丙型肝炎病毒核心转基因小鼠中诱发肝癌的基因改变(S)。为了达到这些目的，我们将采用流体动力学的方法直接将基因(使用表达载体或shRNA构建体)导入小鼠肝细胞中，以实现长期稳定的表达。我们计划在乙型肝炎病毒或丙型肝炎病毒核心转基因小鼠中表达的基因包括：c-Myc、c-Met、N90-2-catenin和sh-p53，这些基因都代表了在人类肝癌发病机制中观察到的常见的遗传修饰。通过将这些特定的基因表达到小鼠的肝脏中，我们将确定当小鼠容易发生由乙肝病毒全基因组或丙型肝炎病毒核心蛋白表达引起的肝癌时，这些基因改变中的任何一个是否能够加速肝癌的发展。综上所述，这些研究将有助于确定在肝癌发病机制中起关键作用的重要驱动癌基因或抑癌基因。这项研究还将在病毒癌蛋白表达的背景下为肝细胞癌发展的分子机制提供新的见解。这项研究产生的小鼠模型将极大地造福于肝癌研究界，并为研究肝癌预防和治疗的新策略提供有价值的体内模型。

DESCRIPTION (provided by applicant): Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths worldwide. HCC is a type of malignancy whose pathogenesis is induced by a combination of genetic and environmental factors. Among the environmental factors, HBV or HCV infections are the major risk factors. Recent molecular and genetic studies have demonstrated that HBV and HCV viral proteins have direct roles during HCC pathogenesis by de-regulating signaling pathways important for hepatocyte proliferation, differentiation and apoptosis.15 However, the long latency and low incidence rate of HCC development from the HBV or HCV transgenic mice studies suggest that additional genetic mutations occur in these damaged hepatocytes, which are required for the malignant transformation and HCC formation. The goal of the proposal is to characterize the virus-gene interactions during hepatic carcinogenesis. We hypothesize that specific genetic events, such as c-Myc or c-Met overexpression, ¿-catenin activating mutations, and loss of tumor suppressor genes TP53, will accelerate HCC development in HBV or HCV core transgenic mice. To test the hypothesis, we propose two Specific Aims. In Aim One, we will determine the genetic alteration(s) that induces hepatic carcinogenesis in HBV transgenic mice; and in Aim Two, we will determine the genetic alteration(s) that induces hepatic carcinogenesis in HCV Core transgenic mice. To achieve these aims, we will apply hydrodynamic transfection method to directly target genes (using either expression vectors or shRNA constructs) into mouse hepatocytes for long term and stable expression. The genes that we plan to express into HBV or HCV core transgenic mice include: c-Myc, c-Met, N90-2-catenin and sh-p53, all representing common genetic modifications observed during human HCC pathogenesis. By expressing these specific genes into the mouse liver, we will determine whether any of these genetic alterations is able to accelerate HCC development when mice are predisposed to hepatic carcinogenesis induced by HBV entire genome or HCV core protein expression. Altogether, the proposed studies will be of great help in identifying important driver oncogenes or tumor suppressor genes that have critical roles during liver cancer pathogenesis. The study will also provide novel insight into the molecular mechanisms of HCC development in the context of viral oncoprotein expression. The murine models generated from the proposed study will significantly benefit HCC research community and provide valuable in vivo models to study novel strategies for HCC prevention and treatment.