持续性乙型肝炎病毒感染调控肝癌细胞膜表面gp130的N-糖基化修饰的分子机制和功能意义研究

Chronic active hepatitis (CAH) induced by persistent hepatitis B virus (HBV) infection remains the major etiologic risk factor for hepatocellular carcinoma (HCC) in China. Cytokine IL-6 and TNF-α secreted by activated Kuffer cells (KCs) in local liver inflammatory microenvironment play essential roles in HBV-associated hepatocarcinogenesis. Previous studies have shown that estrogen-mediated inhibition of IL-6 production by KCs reduces liver cancer risk in females and obesity-promoted HCC development attributes to hepatic inflammation and activation of the oncogenic transcriptional factor STAT3 due to enhanced production of the tumor promoting cytokines IL-6 and TNF-α. Recent investigations found that somatic gp130 activation due to in-frame deletions occurs in 60% of inflammatory hepatocellular adenomas (IHACs), whereas 12% of IHAC subsets lacking gp130 mutations harbor somatic STAT3 mutations. In another report, hepatitis B virus X protein (HBx) stimulates the production of IL-6 in a MyD88-dependent manner in parenchymal liver cells. This project proposal for grant application is designed to elucidate the regulatory effect and functional role of persistent HBV infection during HBV-associated hepatocarcinogenesis on the expression of IL-6 receptor complex including IL-6R and gp130 in hepatoma cells using plasmids containing HBV genome or various HBV encoded gene and human hepatoma cells and tumor tissues. From the point of view in viral oncogenesis and cancer glycobiology, our present research project will focus on the molecular mechanism and functional significance for N-glycosylation-mediated alteration of membrane gp130 protein endocytosis and stability conferred by HBx expression due to persistent HBV infection, and will establish a model of molecular regulation and therapeutic intervention of gp130 N-glycosylation change on hepatoma cells membrane during HBV-associated hepatocarcinogenesis, which paves the way to clinical investigation and drug discovery based on molecular therapy targeting aberrant N-glycosylation and gp130 signal activation in liver cancer patients with chronic hepatitis B.

持续性乙型肝炎病毒（HBV）感染引起的慢性活动性肝炎（CAH）是我国肝癌发生的主要危险因子，肝脏局部炎症微环境中活化枯否细胞（KCs）产生的IL-6和TNF-α在促进肝癌发生过程中发挥重要作用。已有研究证实IL-6/IL-6R/gp130/STAT3信号异常活化在肝癌发生过程中促进肿瘤形成，并且HBV感染可以促进肝实质细胞分泌IL-6。本申请项目以HBV全基因组及其各编码蛋白和人肝癌细胞及组织为研究对象，围绕HBV感染调控肝癌细胞表面IL-6受体包括IL-6R和gp130表达变化及功能意义展开，从病毒致癌机制和肿瘤糖生物学角度出发，研究持续性HBV感染改变肝癌细胞表面gp130蛋白表达的分子机制及功能意义，建立肝癌细胞膜表面gp130分子N-糖基化修饰变化参与乙肝相关肝癌发生的分子调控和干预治疗模型，为开发针对N-糖基化修饰和gp130信号活化的肝癌分子靶向治疗临床研究和药物开发奠定基础。

在本项目资助下，项目负责人围绕肿瘤分子分型与靶向治疗研究方向、在肿瘤微环境研究领域展开研究工作并取得一系列研究成果，以通讯作者在Nat Commun、Cell Death Differ、Ann Surg、Eur J Cancer、Br J Cancer、J Biol Chem、Cell Death Dis、Glycobiology和J Urol等肿瘤学领域国际权威期刊上发表83篇SCI论文， 累计影响因子为340。此外，以相应的科研成果为基础，申请国家发明专利2项，其中一项已于2013年获得授权，另一项目前正处于公开状态。我们发现糖基转移酶Mgat5可以通过活化EGFR/PAK1信号促进肝癌细胞抵抗失巢凋亡并参与肝癌进展过程（Glycobiology. 2013）；我们还发现HBV相关肝癌中HBx蛋白表达引起HNF4α结合减少介导miR-122表达降低决定着肝癌细胞GALNT10信号异常活化并参与肝癌进展和索拉非尼靶向治疗耐药过程（J Biol Chem. 2015）；我们发现EZH2介导的microRNA let-7c表观抑制决定着巨噬细胞PAK1信号异常活化并参与其炎性极化过程（Cell Death Differ. 2015）；我们还发现PAK1介导NF-κB/IL-6信号异常活化决定着肾癌细胞肿瘤干细胞样表型并参与其对舒尼替尼治疗抵抗过程（Cell Death Dis. 2015）；我们发现EZH2介导的miR-622表观抑制决定着肝癌细胞CXCR4信号异常活化并参与肝癌进展过程（Nat Commun. 2015）；我们还发现EZH2介导的PAK6表观抑制决定着肝癌细胞中PAK6信号异常失活并参与肝癌发生发展过程（J Biol Chem. 2015）；我们还发现与发挥促癌作用的GALNT10相反，执行O-GalNAc糖基化修饰的糖基转移酶GALNT家族另外一个成员GALNT4在肝癌发生过程中扮演肿瘤抑制基因的角色，促癌miR-9介导的GALNT4下调参与肝癌发生发展（J Biol Chem. 2017）。