Role of necroptosis in inflammation and NAFLD to HCC progression

项目总结/摘要 本研究的目的是确定肥胖介导的肝细胞慢性炎症的来源 癌（HCC）。肝细胞癌（HCC）是肝癌的一种主要形式，是肝癌的第四大病因。 全球癌症相关死亡人数。近年来，肥胖已成为主要和独立的危险因素 预计到2030年，HCC将成为美国癌症相关死亡的第三大原因 因为肥胖症的流行。肥胖引起的非酒精性脂肪肝（NAFLD），影响近25%的 是肥胖个体中HCC的关键驱动因素。尽管肥胖和肥胖症之间 和HCC，在肥胖中驱动HCC发展的机制尚不清楚。非分辨 慢性炎症是肥胖和损伤中HCC发展和进展的主要因素 相关分子模式（DAMP）是HCC的建议介质之一。坏死性眼睑下垂是一种 程序性细胞死亡已被证明通过释放DAMP在炎症中起主要作用， 其与免疫细胞的细胞表面受体结合以诱导炎症。在本申请中，我们提出， NAFLD中肝细胞坏死性凋亡是HCC进展的关键因素。我们的初步数据支持的作用 HCC中的坏死性凋亡，例如，使用Ripk 3-/-或Mlkl-/-小鼠阻断坏死性凋亡减少了肝脏炎症， 先天性免疫细胞浸润和HCC发病率在喂食胆碱缺乏-高脂肪饮食（CD-HFD）的小鼠中， 不会导致肥胖。在自发性肝癌遗传小鼠模型（Sod 1-/-小鼠）中，使用抑制坏死性凋亡 坏死性凋亡抑制剂necrostatin-1 s可减少肝坏死性凋亡、炎症和介导HCC的途径 发展基于此，我们提出肝细胞坏死是肝脏炎症的主要来源 在HCC发生的微环境中。我们假设NAFLD进展为HCC是由于 由肝细胞坏死引起的炎症增加， 减少炎症和NAFLD向HCC的进展。这一假设将使用遗传学方法进行检验。 通过靶向肝细胞中的RIPK 3或MLKL激酶来阻断或激活肝细胞中的坏死性凋亡的方法 坏死性凋亡途径，并评估其对炎症和HCC的作用。在目标1中，坏死性凋亡将具体表现为 使用肝细胞特异性Ripk 3或Mlkl敲除小鼠在肝细胞中减少/阻断，并确定是否阻断 肝细胞坏死性凋亡减少炎症并延迟/减少HCC发展， 诱导饮食;在目标2中，通过过表达RIPK 3或MLKL将在肝细胞中特异性诱导坏死性凋亡 使用新的Ripk 3或Mlk 1敲入小鼠模型，我们已经开发了用于确定是否诱导坏死性凋亡， 肝细胞的增加导致肝脏炎症增加以及HCC的进展和发病率增加。

Project Summary/Abstract The research objective is to identify the source of chronic inflammation in obesity-mediated hepatocellular carcinoma (HCC). Hepatocellular carcinoma (HCC), a major form of liver cancer, is the fourth leading cause of cancer-related deaths worldwide. In recent years, obesity has emerged as the major and independent risk factor for HCC, and HCC is predicted to the third leading cause of cancer-related deaths in the United States by 2030 due to obesity epidemic. Obesity-induced nonalcoholic fatty liver disease (NAFLD), which affects nearly 25% of the US population, is a key driver of HCC in obese individuals. Despite this strong association between obesity and HCC, the mechanisms that drive HCC development in obesity is not clearly understood. Non-resolving chronic inflammation is a major contributor to the development and progression of HCC in obesity and damage associated molecular patterns (DAMPs) are one of the proposed mediators of HCC. Necroptosis is a programmed cell death that has been shown to play a major role in inflammation through the release of DAMPs, which bind to cell surface receptors of immune cells to induce inflammation. In this application, we propose that hepatocyte necroptosis in NAFLD is a key factor in HCC progression. Our preliminary data support the role of necroptosis in HCC, e.g., blocking necroptosis using Ripk3-/- or Mlkl-/- mice reduced hepatic inflammation, infiltration of innate immune cells, and HCC incidence in mice fed a choline deficient-high fat diet (CD-HFD) that do not induce obesity. In a genetic mouse model of spontaneous HCC (Sod1-/- mice) inhibiting necroptosis using necroptosis inhibitor, necrostatin-1s, reduce hepatic necroptosis, inflammation, and pathways mediating HCC development. Based on this, we propose that hepatocyte necroptosis is the major source of hepatic inflammation in the microenvironment where HCC is initiated. We hypothesize that progression of NAFLD to HCC is due to increased inflammation that arises from hepatocyte necroptosis and that preventing necroptosis will reduce inflammation and progression of NAFLD to HCC. This hypothesis will be tested using genetic approaches to block or activate necroptosis in hepatocytes by targeting RIPK3 or MLKL, kinases in the necroptosis pathway, and assessing its effect on inflammation and HCC. In Aim 1, necroptosis will be specifically reduced/blocked in hepatocytes using hepatocyte specific Ripk3 or Mlkl knockout mice, and determine if blocking hepatocyte necroptosis reduces inflammation and delays/reduces HCC development in response to an HCC- inducing diet; In Aim 2, necroptosis will be induced specifically in hepatocytes by overexpressing RIPK3 or MLKL using a novel Ripk3 or Mlkl knockin mouse model we have developed to determine if inducing necroptosis in hepatocytes leads to an increase in liver inflammation and increased progression and incidence of HCC.