Role of Autotaxin in HCV-associated Hepatocellular Carcinoma

自分泌运动因子在 HCV 相关肝细胞癌中的作用

• 批准号: 8089443
• 负责人: Neerja Kaushik-Basu
• 金额: $ 10.32万
• 依托单位: UNIV OF MED/DENT OF NJ-NJ MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-14 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8089443
• 关键词: Address; Biochemical Genetics; Cell Culture Techniques; Cells; Chronic Hepatitis C; Clinical Research; Coupled; Data; Development; Disease; Employment; Enzymes; Etiology; Exhibits; Genes; Goals; Guanosine Triphosphate Phosphohydrolases; Hepatitis C; Hepatitis C virus; Hepatocyte; Human; Integration Host Factors; Intervention; Investigation; Length; Link; Liver; Liver Fibrosis; Lysophospholipids; Malignant Neoplasms; Mediating; Messenger RNA; Modality; Modeling; Molecular; Molecular Genetics; Open Reading Frames; Pathogenesis; Patients; Plasma; Play; Prevention; Primary carcinoma of the liver cells; Proteins; RNA replication; Regulation; Replicon; Reporting; Risk Factors; Role; Sampling; Serum; Signal Pathway; Signal Transduction; Staging; Testing; Therapeutic Intervention; Tissues; Tumor Tissue; Viral Pathogenesis; Viral Proteins; Virus Diseases; Virus Replication; base; cancer cell; cancer type; hepatoma cell; insight; lysophosphatidic acid; mRNA Expression; novel; phosphoric diester hydrolase; promoter; public health relevance; pyrophosphatase; research study; response; rho GTP-Binding Proteins; tumor; tumorigenic; viral RNA; virus pathogenesis

DESCRIPTION (provided by applicant): Hepatitis C virus (HCV) infection is the most significant risk factor for the development of hepatocellular carcinoma (HCC), a major liver malignancy and cancer type worldwide. The molecular genetics and signaling pathways associated with HCV-associated HCC pathogenesis remain poorly understood. Our long-term goal is to elucidate the molecular mechanisms underlying progression of chronic HCV to HCC. Autotaxin (ATX), an ectonucleotide pyrophosphatase/phosphodiesterase 2 enzyme and a potent cell stimulating motogen is over-expressed in various malignant tumor tissues and has been implicated to confer the tumorigenic and metastatic potential of a variety of cancer cells. In 2007, two groups provided the first evidence that the serum ATX activity and plasma lysophosphatidic acid (LPA) levels are increased in chronic hepatitis C in association with liver fibrosis, and that ATX and genes related to ATX signaling pathway were upregulated in HCC patients co-infected with HCV. Is this the cause or consequence of HCV infection? And how does aberrant regulation of ATX impact HCV replication and pathogenesis? We postulate that "ATX over-expression and signaling may be an important determinant in the replication and pathogenesis of HCV". Our hypothesis is based on some novel and vital clues linking ATX expression to HCV infection and pathogenesis. In preliminary experiments we observed that ATX mRNA expression is upregulated in the liver tissues of HCV-infected patients and its expression is further enhanced in HCV- associated HCC samples, consistent with the 2007 clinical study. Further, the expression levels of ATX mRNA were upregulated in HCV replicon cells versus replicon cured cells, suggesting a role for HCV in inducing ATX expression. This observation coupled with our data that HCV replicon cells secrete ATX, suggest that the HCV infected liver may potentially contribute to the aberrant expression of ATX in HCV- infected patients and patients with HCV-associated HCC. We found that the ATX promoter was activated and stimulated in HCV replicon cells, thus implicating HCV proteins and host-factors in HCV-infected cells to potentially play a role in aberrant regulation of ATX. Further, over-expression of ATX in HCV RNA bearing human hepatoma cells induced RhoA expression, activated RhoA and stimulated HCV RNA replication. Conversely, blockage of ATX secretion abrogated RhoA induction and ablated HCV RNA replication. We envision that ATX/LPA over-expression during the course of HCV infection may de-regulate mechanisms involved in Rho GTPase signaling thus contributing towards HCV pathogenesis. To test our hypothesis and to extend our findings two independent but complementary specific aims are proposed. In Aim 1 we will investigate the role of viral proteins and host factors in aberrant regulation of ATX expression during HCV infection and pathogenesis. In Aim 2, we propose to address the role of ATX in HCV replication and pathogenesis mechanisms. To investigate these aspects, we propose to employ nontransformed human hepatocytes (HH4 cells) conditionally expressing the full-length HCV ORF (HH4-HCV) as models for the early stage of HCV infection, and C-5B replicon cells which replicate HCV RNA in hepatoma cells to address questions pertaining to the scenario in the HCV infected tumor microenvironment. These objectives will be achieved via multi-prong approach, including cell culture, biochemical and molecular genetics. We envisage that our findings will provide crucial insights into modulation of ATX during HCV infection and further clarify the role of ATX in HCV replication and pathogenesis. These investigations may provide rational target for therapeutic intervention of HCV. PUBLIC HEALTH RELEVANCE: The proposed studies have the potential to provide crucial insights into regulation and role of autotaxin (ATX), a tumorigenic and metastatic protein, in HCV infection and pathogenesis mechanisms and may likely identify novel modalities for therapeutic intervention of Hepatitis C.

描述（由申请人提供）：丙型肝炎病毒（HCV）感染是发展为肝细胞癌（HCC）的最重要危险因素，HCC是世界范围内主要的肝脏恶性肿瘤和癌症类型。与hcv相关的HCC发病机制相关的分子遗传学和信号通路仍然知之甚少。我们的长期目标是阐明慢性HCV发展为HCC的分子机制。Autotaxin （ATX）是一种外核苷酸焦磷酸酶/磷酸二酯酶2酶，是一种有效的细胞刺激原，在多种恶性肿瘤组织中过度表达，并被认为与多种癌细胞的致瘤性和转移潜力有关。2007年，两组研究人员首次提供了慢性丙型肝炎患者血清ATX活性和血浆溶血磷脂酸（LPA）水平升高与肝纤维化相关的证据，以及ATX和ATX信号通路相关基因在丙型肝炎合并HCC患者中上调的证据。这是丙型肝炎病毒感染的原因还是后果？ATX异常调控如何影响HCV复制和发病机制？我们假设“ATX过表达和信号传导可能是HCV复制和发病机制的重要决定因素”。我们的假设是基于一些将ATX表达与HCV感染及其发病机制联系起来的新颖而重要的线索。在初步实验中，我们观察到ATX mRNA在HCV感染患者的肝组织中表达上调，并且在HCV相关的HCC样本中表达进一步增强，与2007年的临床研究一致。此外，与复制子固化的细胞相比，HCV复制子细胞中ATX mRNA的表达水平上调，这表明HCV在诱导ATX表达方面发挥了作用。这一观察结果与我们关于HCV复制子细胞分泌ATX的数据相结合，表明HCV感染的肝脏可能导致HCV感染患者和HCV相关HCC患者中ATX的异常表达。我们发现ATX启动子在HCV复制子细胞中被激活和刺激，从而暗示HCV感染细胞中的HCV蛋白和宿主因子可能在ATX的异常调节中发挥作用。此外，ATX在携带HCV RNA的人肝癌细胞中过表达可诱导RhoA表达，激活RhoA并刺激HCV RNA复制。相反，阻断ATX分泌可消除RhoA诱导并抑制HCV RNA复制。我们设想，在HCV感染过程中，ATX/LPA的过表达可能会解除Rho GTPase信号通路的调节机制，从而促进HCV的发病。为了验证我们的假设并扩展我们的发现，提出了两个独立但互补的具体目标。在Aim 1中，我们将研究病毒蛋白和宿主因子在HCV感染和发病过程中对ATX表达的异常调节中的作用。在目的2中，我们提出解决ATX在HCV复制和发病机制中的作用。为了研究这些方面，我们建议使用有条件表达全长HCV ORF （HH4-HCV）的非转化人肝细胞（HH4细胞）作为HCV感染早期的模型，以及在肝癌细胞中复制HCV RNA的C-5B复制子细胞来解决HCV感染肿瘤微环境中有关情况的问题。这些目标将通过多管齐下的方法来实现，包括细胞培养、生化和分子遗传学。我们设想我们的研究结果将为HCV感染期间ATX的调节提供重要的见解，并进一步阐明ATX在HCV复制和发病机制中的作用。这些研究可为HCV的治疗干预提供合理的靶点。