SENESCENCE AND APOPTOSIS IN HBV ASSOCIATED HCC

乙型肝炎相关肝癌的衰老和细胞凋亡

• 批准号: 6172249
• 负责人: MARK A FEITELSON
• 金额: $ 23.53万
• 依托单位: THOMAS JEFFERSON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-03-01 至 2003-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6172249
• 关键词: athymic mouse; complementary DNA; gene deletion mutation; genetic library; genetically modified animals; hepatitis B antigens; hepatitis B virus group; hepatocellular carcinoma; human tissue; intermolecular interaction; laboratory mouse; neoplasm /cancer genetics; phosphoproteins; tissue /cell culture; transcription factor; viral carcinogenesis

The proposed work aims to test the hypothesis that the abrogation of negative regulatory pathways is central to the mechanism whereby hepatitis B virus (HBV) encoded X antigen ( HBXAg) causes hepatocellular carcinoma (HCC). This hypothesis is premised on the finding that HBxAg binds to and apparently inactivates a senescence factor (p55sen) isolated from a yeast two-hybrid screen, that it apparently suppresses the expression of another cellular gene with considerable homology to another senescence factor (p45SRF) using a PCR select cDNA subtraction approach, and that HBXAg appears to transcriptionally suppress the known senescence factor p21 WAF1ISDI1/CIP1. In order to evaluate the role of these senescence factors in hepatocarcinogenesis a series of HBXAg mutants will be tested for their ability to bind p55sen and/or down regulate p45 SRF or p21WAF1. Those mutants which do not bind p55 sen or fail to down regulate 45SRF or p21WAF1, will then be screened in a number of cell based assays which score for properties relevant to hepatocellular transformation. Preliminary work by the principal investigator has shown that HBxAg expressed in liver cell lines increases the resistance of these cell lines to anti-Fas and TGFb1 mediated apoptosis promotes cell survival in seru free medium, and stimulates growth in culture, in soft agar, and in nude mice. Hence, the proposed work in the first specific aim intends to determine whether HBXAg mutants which fail to bind to or down regulate one or more of these senescence factors correlate with the loss in one or more of these cellular phenotypes. The experiments aim to identify the importance of senescence factor inactivation to hepatocellular transformation mediated by HBxAg, which will contribute crucially to the understanding of HBV associated multistep hepatocarcinogenesis. The second specific aim aims to identify additional components of the p55sen and p45SRF pathways and the mechanism which mediates negative growth regulation. Other experiments are planned to assess whether HBXAg own regulation of p21WAF1 correlates with inactivation of the retinoblastoma gene product.

拟议的工作旨在检验这一假设， 负调节途径是肝炎机制的核心， B病毒（HBV）编码的X抗原（HBXAg）导致肝细胞癌 （HCC）。这一假设是基于HBxAg结合并 从酵母中分离的衰老因子（p55 sen）明显失活 双杂交屏幕，它显然抑制了另一个表达 与另一种衰老因子具有相当同源性的细胞基因 （p45 SRF），并且HBXAg 似乎在转录上抑制已知的衰老因子p21 WAF1ISDI1/CIP1。为了评估这些衰老因子的作用 在肝癌发生中，将测试一系列HBXAg突变体的 结合p55 sen和/或下调p45 SRF或p21 WAF 1的能力。那些 不结合p55 sen或不能下调45 SRF的突变体， p21 WAF 1，然后将在许多基于细胞的测定中筛选， 与肝细胞转化相关的性质评分。 主要研究者的初步工作表明，HBxAg 在肝细胞系中表达增加了这些细胞系的抗性 抗Fas和TGF β 1介导的凋亡促进血清中细胞存活 自由培养基，并刺激在培养物中，在软琼脂中和在裸 小鼠因此，第一个具体目标中的拟议工作旨在 确定HBXAg突变体是否不能结合或下调一个 这些衰老因子中的一种或多种与一种或多种衰老因子的丧失相关。 这些细胞表型。这些实验旨在确定 衰老因子失活对肝细胞重要性 由HBxAg介导的转化，这将对 了解HBV相关的多步骤肝癌发生。第二 具体目标旨在确定p55 sen的其他组成部分， p45 SRF通路及其介导负性生长的机制 调控计划进行其他实验以评估HBXAg是否具有 p21 WAF 1的调节与视网膜母细胞瘤的失活相关 基因产物