Hepatitis C virus core protein and cell proliferation

描述（由申请人提供）：丙型肝炎病毒（HCV）感染导致急性和慢性肝炎、肝脂肪变性、肝硬化，最终导致肝细胞癌（HCC）。HCV感染导致HCC形成的分子事件仍然知之甚少。HCV核心蛋白被认为是导致氧化应激、脂肪变性和致癌的关键病毒成分之一。为此，我们建立了瞬时高效表达HCV核心蛋白的人肝癌细胞模型。表达核心蛋白的细胞，特别是lb基因型的细胞，表现出增加的增殖和细胞周期的进展。微阵列分析显示，参与细胞生长和致癌信号通路的基因上调，以响应核心蛋白的表达。特别令人感兴趣的是wnt-1及其下游靶点WISP-2的上调。这些结果提示wnt-1信号通路可能被HCV核心蛋白激活，部分介导核心蛋白诱导的细胞增殖。已知wnt-1信号通路在细胞生长和肿瘤发生中起重要作用。wnt-1通路的失调已在包括肝癌在内的许多人类肿瘤中被发现。因此，进一步表征HCV核心表达细胞中的wnt-1/WISP-2信号通路及其对肝细胞生长的调控作用，可能有助于探讨该核心蛋白诱导细胞增殖的机制。特异性Aim 1将确定核心蛋白刺激细胞增殖的结构-功能基础。负责的序列将由缺失突变体定义，基因型特定的决定因素将通过嵌合结构定位。特异性Aim 2将研究wnt-1/WISP-2信号通路在介导细胞增殖增强中的作用。我们将进一步验证wnt-1/ β -catenin通路的激活确实是由HCV核心蛋白激活的，并检验抑制wnt-1/WISP-2蛋白的表达是否会阻断核心蛋白诱导的细胞生长。这些研究可能阐明核心诱导细胞增殖的分子机制，为HCV诱导肝癌的预防提供新的靶点。

DESCRIPTION (provided by applicant): Hepatitis C virus (HCV) infection causes acute and chronic hepatitis, liver steatosis, cirrhosis, and eventually hepatocellular carcinoma (HCC). The molecular events of HCV infection leading to HCC formation are still poorly understood. HCV core protein has been proposed to be one of the key viral components contributing to oxidative stress, steatosis, and carcinogenesis. In this regard, we have established a human hepatoma cell model of transient and efficient HCV core protein expression. Cells expressing core protein, especially of the lb genotype, displayed increased proliferation and cell cycle progression. Microarray analysis revealed upregulation of genes involved in cell growth and oncogenic signaling pathways in response to core protein expression. Of particular interest is the up-regulation of both wnt-1 and its downstream target WISP-2. These observations suggest that wnt-1 signaling pathway may be activated by HCV core protein and partly mediate cell proliferation induced by the core protein. The wnt-1 signaling pathway is known to play an important role in cell growth and tumorogenesis. The disregulation of wnt-1 pathway has been found in many human tumors including liver cancer. Therefore, further characterization of wnt-1/WISP-2 signaling in HCV core expressing cells and its effect on regulation of liver cell growth may probe into the mechanisms by which the core protein induced cell proliferation. Specific Aim 1 will determine the structural-functional basis whereby the core protein stimulates cell proliferation. The responsible sequence will be defined by deletion mutants, and genotype specific determinant(s) will be located via chimeric constructs. Specific Aim 2 will examine the role of wnt-1/WISP-2 signaling pathway in mediating enhanced cell proliferation. We will further validate activation of the wnt-1/beta-catenin pathway is indeed activated by HCV core protein and examine whether inhibition of wnt-1/WISP-2 protein expression will block cell growth as elicited by core protein. These studies may elucidate molecular mechanisms of core induced cell proliferation and provide novel targets for prevention of HCV induced liver cancer.