Beta-Catenin Signaling in HBxAg Mediated HCC.

HBxAg 介导的 HCC 中的 β-连环蛋白信号传导。

• 批准号: 7029055
• 负责人: MARK A FEITELSON
• 金额: $ 27.59万
• 依托单位: THOMAS JEFFERSON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-06 至 2011-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7029055
• 关键词: apoptosis; biological signal transduction; cadherins; flow cytometry; gene expression; genetically modified animals; hepatitis B antigens; hepatitis B virus group; hepatocellular carcinoma; immediate early protein; laboratory mouse; liver cells; messenger RNA; neoplastic growth; neoplastic transformation; nuclear runoff assay; nucleic acid biosynthesis; phosphatidylinositol 3 kinase; pleiotropism; proteasome; protein degradation; regulatory gene; serine threonine protein kinase; terminal nick end labeling; tissue /cell culture; transfection

DESCRIPTION (provided by applicant): Hepatitis B virus (HBV) encoded x antigen (HBxAg) is a trans-activating protein that contributes to the development of hepatocellular carcinoma (HCC) by the up- or down-regulated expression of selected hepatocellular genes. To identify some of these genes, HBxAg or vector were introduced into the human hepatoblastoma cell line, HepG2. Differentially expressed genes were identified by microarray analysis and by PowerBlot (SDS/PAGE followed by western blotting). Both assays showed decreased E-cadherin and increased expression of b-catenin and several b-catenin target genes in HBxAg [+] compared to [-] cells. In the livers of HBV carriers, there was an inverse relationship between HBxAg staining and E-cadherin and co- staining between HBxAg and b-catenin, suggesting that HBxAg contributes to hepatocellular transformation by altering the b-catenin signaling pathway. Hence, the objective of this work is to elucidate the mechanisms whereby HBxAg stabilizes b-catenin and thereby stimulates signaling, and to determine the contribution of these mechanisms to HBxAg mediated transformation. Accordingly, experiments will test the hypothesis that the accumulation/activation of b-catenin in HBxAg positive cells results from HBxAg trans-activation of the b-catenin gene, from HBxAg inactivation of glycogen synthase kinase 3b (GSKSp), from the HBxAg down-regulation of E-cadherin, and/or from the HBxAg inhibition of b-catenin degradation in the proteasome (Aim 1). Additional experiments will test whether the HBxAg stabilization of b-catenin contributes to the pathogenesis of HCC (Aim 2). These experiments will establish the extent to which up-regulated b-catenin signaling underlies the pleiotropic properties whereby HBxAg contributes to HCC development on the molecular level, and the corresponding mechanism(s) whereby this occurs. Given that wild type b-catenin is up-regulated in the majority of HBV associated HCCs, elucidation of the underlying mechanism(s) will identify critical pathways that will be targeted for chemoprevention of HCC and for therapeutic intervention in tumor bearing patients. The results from this research would also provide therapeutic targets for the application of existing drugs (against b-catenin effectors) in patients with HCC. In doing so, the proposed work is expected to promote the development of multiple public health benefits for HBV infected carriers with chronic liver disease and HCC.

描述(由申请人提供)：乙肝病毒编码的x抗原(HBxAg)是一种反式激活蛋白，通过上调或下调选定的肝细胞基因的表达而促进肝细胞癌(HCC)的发展。为了鉴定其中的一些基因，将HBxAg或载体导入人肝母细胞瘤细胞系HepG2。通过基因芯片分析和免疫印迹(SDS/PAGE和Western blotting)鉴定差异表达基因。两种检测结果均显示HBxAg[+]细胞与[-]细胞相比，E-钙粘附素表达降低，b-连环蛋白和几个b-连环蛋白靶基因表达增加。在乙肝病毒携带者的肝脏中，HBxAg染色与E-钙粘附素呈负相关，HBxAg与b-catenin共染色，提示HBxAg通过改变b-catenin信号通路参与肝细胞转化。因此，这项工作的目的是阐明HBxAg稳定b-连环蛋白从而刺激信号转导的机制，并确定这些机制在HBxAg介导的转化中的作用。因此，实验将检验这一假设，即HBxAg阳性细胞中b-catenin的积累/激活是由于HBxAg反式激活b-catenin基因，由于HBxAg使糖原合成酶3b(GSKSp)失活，由于HBxAg下调E-钙粘蛋白，和/或由于HBxAg抑制蛋白酶体中b-catenin的降解(目标1)。其他实验将测试b-连环蛋白的HBxAg稳定性是否有助于肝癌的发病(目标2)。这些实验将确定上调的b-连环蛋白信号在多大程度上支持HBxAg在分子水平上促进肝癌发展的多效性，以及发生这种情况的相应机制(S)。鉴于野生型b-catenin在大多数与乙肝病毒相关的肝癌中上调，阐明其潜在机制(S)将确定针对肝癌的化学预防和对携带肿瘤患者的治疗干预的关键途径。这项研究的结果也将为现有药物(针对b-连环蛋白效应物)在肝细胞癌患者中的应用提供治疗靶点。通过这样做，拟议的工作有望促进为患有慢性肝病和肝细胞癌的乙肝病毒感染携带者发展多种公共健康益处。