Control of stellate cells-driven liver cancer by the p62/NBR1 adapters

 描述（由申请人提供）：本提案的长期目标是有助于理解肝星状细胞（HSC）促进肝细胞癌（HCC）进展的分子信号传导机制。纤维化和炎症微环境是非酒精性脂肪性肝炎（NASH）的标志，并且越来越多地被认为有助于肝硬化，HCC和终末期肝病。这需要肝移植，并且通常是肝病进展的下一步， 脂肪肝患者的重要子集（在美国高达1000万）。因此，确定导致NASH发展的细胞和分子因素以及如何导致HCC是理解其发病机制的主要差距。最近的研究结果表明，肝星状细胞（HSC），肝损伤后分化成肌成纤维细胞，并协调细胞外成分的产生，形成纤维化瘢痕和炎症，是控制HCC发展的核心球员。这一提议基于我们在小鼠中的初步体外和体内研究，以及对人类HCC数据集的分析，强烈表明信号转导衔接子p62和NBR 1是NASH和HCC发展中的关键参与者，并且它们通过涉及TGFβ信号转导负调控的新范式调节HSC的功能和活性来发挥作用。在此，我们将通过解决以下目的来测试该假设：（目的1）通过以下方式确定p62和NBR 1在细胞自主水平的HSC活化中的分子作用机制：（1.1）确定NBR 1消融对HSC活化中TGFβ信号传导的影响;和（1.2）解开p62和NBR 1与TGFβ信号传导级联的不同组分之间的详细生物化学联系。(Aim 2）在细胞特异性体内小鼠模型中，通过以下方式确定HSC中p62/NBR 1信号级联对NASH和HCC控制的贡献：（2.1）表征p62和/或NBR 1的HSC特异性敲除小鼠并确定它们对NASH和HCC发展的贡献;（2.2）在体内确定HSC中p62和/或NBR 1缺陷改变的信号传导途径;和（2.3）确定HSC中p62和NBR 1的临床相关性。这些研究的结果将有助于确定新的生物标志物来预测NAFLD-NASH- HCC的转变，以及预防和治疗这些肝脏病变的新的治疗靶点。

 DESCRIPTION (provided by applicant): The long-term goal of this proposal is to contribute to the understanding of the molecular signaling mechanisms whereby hepatic stellate cells (HSC) promote hepatocellular carcinoma (HCC) progression. Fibrosis and the inflammatory microenvironment are hallmarks of non-alcoholic steatohepatitis (NASH), and that are increasingly recognized as conducive to cirrhosis, HCC, and end-stage liver disease. This requires liver transplantation, and quite often is the next step in liver disease progression for a significant subset of patients with fatty liver (up to 10 million in the US). Therefore, the identification of the cellular and molecular factors that account for NASH development and how that leads to HCC is a major gap in the understanding of its pathogenesis. Recent results indicate that hepatic stellate cells (HSCs), which differentiate to myofibroblasts upon liver injur and orchestrate the production of extracellular components that form the fibrotic scar and inflammation, are central players in the control of HCC development. This proposal in based on our preliminary in vitro and in vivo studies in mice, and in the analysis of human HCC data sets, strongly suggesting that the signaling adapters p62 and NBR1 are critical players in NASH and HCC development, and that they act by regulating the function and activity of HSCs through a new paradigm involving the negative regulation of TGFβ signaling. Here we will test this hypothesis by addressing the following Aims: (Aim 1) Determine the molecular mechanisms of action of p62 and NBR1 in HSC activation at a cell autonomous level by: (1.1) determining the impact that NBR1 ablation has on TGFβ signaling in HSC activation; and (1.2) unraveling the detailed biochemical links between p62 and NBR1 with different components of the TGFβ signaling cascade. (Aim 2) Determine the contribution of the p62/NBR1 signaling cascade in HSCs to the control of NASH and HCC in cell-specific in vivo mouse models by: (2.1) characterizing HSC-specific knockout mice for p62 and/or NBR1 and determining their contribution to NASH and HCC development; (2.2) determining the signaling pathways altered by p62 and/or NBR1 deficiency in HSCs in vivo; and (2.3) determining the clinical relevance of p62 and NBR1 in HSCs. Results from these studies will serve to identify new biomarkers to predict the NAFLD-NASH- HCC transition, as well as new therapeutic targets for prevention and treatment of these liver pathologies.