DataSheet_1_Intracellular Accumulation of IFN-λ4 Induces ER Stress and Results in Anti-Cirrhotic but Pro-HCV Effects.docx

IFNL3/IFNL4 polymorphisms are inversely associated with the risk of chronic hepatitis C virus (HCV) infection and cirrhosis, two major risk factors for developing hepatocellular carcinoma (HCC). To further explore these inverse associations and their molecular underpinnings, we analyzed IFNL3/IFNL4 polymorphisms represented by the IFNL4 genotype (presence of rs368234815-dG or rs12979860-T alleles) in HCV patients: 2969 from Japan and 2931 from Taiwan. IFNL4 genotype was associated with an increased risk of HCV-related HCC (OR=1.28, 95%CI=1.07-1.52, P=0.0058) in the general population of Japanese patients, but not in Taiwanese patients who achieved treatment-induced viral clearance. IFNL4 genotype was also associated with a decreased risk of cirrhosis (OR=0.66, 95%CI=0.46-0.93, P=0.018, in Taiwanese patients). We then engineered HepG2 cells to inducibly express IFN-λ4 in the presence or absence of interferon lambda receptor 1 (IFNLR1). Induction of IFN-λ4 resulted in its intracellular accumulation, mainly in lysosomes and late endosomes, and increased ER stress, leading to apoptosis and reduced proliferation. We identified the very-low-density lipoprotein receptor (VLDLR), which facilitates HCV entry into hepatocytes, as a transcript induced by IFN-λ4 but not IFN-λ3. Our results suggest that the molecular mechanisms underlying the anti-cirrhotic but pro-HCV associations observed for IFNL3/IFNL4 polymorphisms are, at least in part, contributed by intracellular accumulation of IFN-λ4 causing ER stress in hepatic cells.

IFNL3/IFNL4 基因多态性与慢性丙型肝炎病毒（hepatitis C virus, HCV）感染及肝硬化的发病风险呈负相关，而二者均为肝细胞癌（hepatocellular carcinoma, HCC）发生的两大主要危险因素。为进一步探究这类负相关关联及其分子机制，我们针对丙型肝炎病毒感染者的IFNL3/IFNL4基因多态性——以IFNL4基因型为代表，即rs368234815-dG等位基因或rs12979860-T等位基因的携带情况——展开分析，研究对象共包含2969名日本患者与2931名中国台湾患者。在日本患者的总体人群中，IFNL4基因型与丙型肝炎病毒相关肝细胞癌的发病风险升高显著相关（优势比OR=1.28，95%置信区间CI=1.07-1.52，P=0.0058），但在获得治疗诱导病毒清除的中国台湾患者中未观察到该关联。IFNL4基因型还与肝硬化的发病风险降低相关（中国台湾患者中：OR=0.66，95%CI=0.46-0.93，P=0.018）。我们随后构建了可在干扰素λ受体1（interferon lambda receptor 1, IFNLR1）存在或缺失的情况下诱导表达IFN-λ4的HepG2细胞模型。IFN-λ4的诱导表达可导致其在细胞内积累，主要定位于溶酶体与晚期内体，并加剧内质网应激，最终引发细胞凋亡并抑制细胞增殖。我们还鉴定出极低密度脂蛋白受体（very-low-density lipoprotein receptor, VLDLR）——一种可介导丙型肝炎病毒侵入肝细胞的蛋白——是受IFN-λ4诱导而非IFN-λ3诱导的转录本。本研究结果提示，IFNL3/IFNL4基因多态性所呈现的抗肝硬化但促丙型肝炎病毒相关肝细胞癌的分子机制，至少部分是由IFN-λ4在肝细胞内的积累引发内质网应激所介导的。