Hepatitis B virus X protein modulation of calcium signaling in HCC development

乙型肝炎病毒 X 蛋白对 HCC 发展中钙信号的调节

• 批准号: 8536585
• 负责人: Jessica Casciano
• 金额: $ 4.06万
• 依托单位: DREXEL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8536585
• 关键词: Address; Affect; Apoptosis; Area; Biological Models; Ca(2+)-Calmodulin Dependent Protein Kinase; Calcineurin; Calcium; Calcium Signaling; Calmodulin; Calmodulin-Binding Proteins; Cancer Etiology; Cancer Model; Cell Cycle; Cell Line; Cell Proliferation; Cell Proliferation Regulation; Cell physiology; Cells; Cessation of life; Chronic; Chronic Hepatitis B; Couples; Cyclic AMP-Responsive DNA-Binding Protein; Cyclin D1; Cyclin E; Cytosol; Development; Distal; Environment; Event; Exposure to; Genome; Goals; Hepatitis B; Hepatitis B Incidence; Hepatitis B Virus; Hepatitis B X-Protein; Hepatoblastoma; Hepatocarcinogenesis; Hepatocyte; Human; Immune; Individual; Infection; Infectious Agent; Investigation; Kinetics; Link; Liver Regeneration; Malignant Neoplasms; Malignant neoplasm of liver; Mediating; Methods; Monitor; Mus; Neoplasm Metastasis; Normal Cell; Pathway interactions; Physiology; Play; Primary carcinoma of the liver cells; Process; Proteins; Rattus; Regulation; Rodent; Role; Signal Transduction; Signal Transduction Pathway; Toxin; Transgenic Mice; Transgenic Organisms; Viral Proteins; Virus Diseases; Virus Replication; activating transcription factor; c-myc Genes; cancer initiation; cell type; extracellular; mortality; mouse model; new therapeutic target; novel; nuclear factors of activated T-cells; protein activation; protein expression; tumor

DESCRIPTION (provided by applicant): Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide and third highest cause of cancer-related deaths. Although the development of HCC has been linked to exposure to various toxins or infectious agents, the majority of HCC cases are associated with chronic hepatitis B virus (HBV) infections. Worldwide, there are over 350 million people chronically infected with HBV, and approximately 25 percent of these individuals will eventually develop HCC. The high incidence of HBV infections, the high mortality rate of individuals with HCC, the increasing occurrence of HCC, and the strong association between chronic HBV infections and HCC development indicates that investigating the mechanisms underlying the development of HBV-associated HCC is a critically important area of investigation. While not entirely understood, these underlying mechanisms are thought to involve the immune-mediated destruction of HBV-infected hepatocytes and compensatory liver regeneration as well as activities of the multifunctional HBV X protein (HBx). HBx has been shown to be required for HBV replication and is thought to play at least a co-factor role in HCC development. Ca2+ signaling influences almost every cellular process and has been shown to play a critical role in many aspects of cancer development; the Ca2+-binding protein calmodulin (CaM) is thought to be a major contributor to cancer development and is required for cell proliferation. Interestingly, HBx regulation of Ca2+ signals is thought to act as an upstream initiating event for many other HBx effects, and Ca2+ has been shown to be required for HBx regulation of cell proliferation, apoptosis and HBV replication. We hypothesize that HBx modulates store-operated Ca2+ (SOC) entry (SOCE) to increase cytosolic Ca2+ levels and stimulate HBV replication, while consequently de-regulating normal hepatocyte Ca2+ signaling to increase CaM activation and CaM-dependent modulation of cell proliferation. The goal of this application is to define the effect of HBx on SOCE in cultured primary rodent hepatocytes, a biologically relevant model system, and how this regulation affects HBV replication, CaM signaling, and CaM-mediated cell proliferation. In Aim 1, we will investigate HBx regulation of SOCE using kinetic Ca2+ studies. We will also determine the impact of HBx on expression levels of SOC channel components and how this affects HBV replication. In Aim 2, we will investigate additional consequences of HBx regulation of Ca2+ by analyzing the impact of HBx on CaM signaling and CaM regulation of cell proliferation. In Aim 3, we will address the significance of HBx regulation of SOCE and CaM signaling for HCC development by utilizing an HBx-transgenic mouse liver cancer model; we will disrupt SOCE and CaM in these mice and determine the impact on HCC development. Overall, we expect that our studies will identify mechanisms by which HBx alters hepatocyte physiology to promote HBV replication and HCC development. Our studies may also identify new therapeutic targets for blocking HBx activities and HBV replication and the development of HBV-associated HCC.

描述（由申请人提供）：肝细胞癌（HCC）是全球第六大常见癌症，也是癌症相关死亡的第三大原因。虽然HCC的发生与暴露于各种毒素或感染因子有关，但大多数HCC病例与慢性B型肝炎病毒（HBV）感染有关。在全球范围内，有超过3.5亿人慢性感染HBV，其中约25%的人最终将发展为HCC。HBV感染的高发病率、HCC患者的高死亡率、HCC的发生率增加以及慢性HBV感染与HCC发展之间的强相关性表明，研究HBV相关HCC发展的潜在机制是一个非常重要的研究领域。虽然尚未完全理解，但这些潜在机制被认为涉及免疫介导的HBV感染肝细胞的破坏和代偿性肝再生以及多功能HBV X蛋白（HBx）的活性。HBx已被证明是HBV复制所必需的，并且被认为在HCC发展中至少起辅助因子作用。Ca 2+信号传导影响几乎每一个细胞过程，并已被证明在癌症发展的许多方面发挥关键作用; Ca 2+结合蛋白钙调蛋白（CaM）被认为是癌症发展的主要贡献者，也是细胞增殖所必需的。有趣的是，HBx对Ca 2+信号的调节被认为是许多其他HBx效应的上游起始事件，并且Ca 2+已被证明是HBx调节细胞增殖、凋亡和HBV复制所需的。我们假设HBx调节钙池操纵的钙（SOC）进入（SOCE），以增加胞浆钙水平并刺激HBV复制，同时因此解除正常肝细胞钙信号传导的调节，以增加钙调素激活和钙调素依赖性调节细胞增殖。本申请的目的是确定HBx对培养的原代啮齿动物肝细胞（一种生物学相关模型系统）中SOCE的影响，以及这种调节如何影响HBV复制、CaM信号传导和CaM介导的细胞增殖。在目标1中，我们将使用动力学Ca 2+研究来研究HBx对SOCE的调节。我们还将确定HBx对SOC通道组分表达水平的影响以及这如何影响HBV复制。在目标2中，我们将通过分析HBx对CaM信号传导和CaM调节细胞增殖的影响来研究HBx调节Ca 2+的其他后果。在目标3中，我们将通过利用HBx转基因小鼠肝癌模型来解决HBx调节SOCE和CaM信号对HCC发展的意义;我们将在这些小鼠中破坏SOCE和CaM，并确定对HCC发展的影响。总的来说，我们希望我们的研究将确定HBx改变肝细胞生理学以促进HBV复制和HCC发展的机制。我们的研究还可能确定新的治疗靶点，用于阻断HBx活性和HBV复制以及HBV相关HCC的发展。