title: Hepatitis C virus core protein epigenetically silences SFRP1 and enhances HCC aggressiveness by inducing epithelial-mesenchymal transition.
abstract: Hepatocellular carcinoma (HCC) is one of the most deadly cancers. Aberrant oncogenic activation of the Wnt/β-catenin signaling pathway contributes to hepatocellular carcinogenesis. Various epigenetic modifications of the Wnt antagonist secreted frizzled-related protein (SFRP) family have been implicated in regulating Wnt signaling. Here, we report that Hepatitis C virus (HCV) core protein downregulates SFRP1 expression when it is expressed in Huh7 and HepG2 cells. SFRP1 expression can be effectively restored by using either a DNA methylation inhibitor alone or in combination with a histone deacetylase inhibitor. DNA methylation analysis of the SFRP1 promoter revealed that cytosine-phosphate-guanine (CpG) islands close to the transcriptional start site (TSS) in the SFRP1 promoter were hypermethylated in core-expressing Huh7 cells, suggesting that HCV core protein may downregulate SFRP1 expression by inducing hypermethylation of the SFRP1 promoter. Chromatin immunoprecipitation revealed that HCV core protein markedly increased the expression level and binding of DNA methyltransferase-1 (Dnmt1) and histone deacetylase-1 (HDAC1) to the TSS of the SFRP1 promoter region, resulting in repression of acetyl-histone H3-binding capacity to SFRP1 promoter and the eventual epigenetic silencing of SFRP1 expression. Furthermore, the core protein-promoted cell proliferation, migration and invasiveness were effectively abrogated either by Dnmt1 knockdown or restoration of SFRP1 expression in hepatoma cells. Dnmt1 knockdown or SFRP1 overexpression also inhibited HCV core-induced epithelial-mesenchymal transition (EMT) and significantly decreased the expression levels of activated β-catenin and Wnt/β-catenin target genes, c-Myc and cyclin D1. We further showed that knockdown of Dnmt1 and restoration of SFRP1 inhibited core-induced in vivo tumor growth and aggressiveness in a xenograft HCC model. Taken together, our results strongly suggest that the HCV core-induced epigenetic silencing of SFRP1 may lead to the activation of the Wnt signaling pathway and thus contribute to HCC aggressiveness through induction of EMT.
authors.affiliation: The Second Affiliated Hospital and the Key Laboratory of Molecular Biology of Infectious Diseases designated by the Chinese Ministry of Education, Chongqing Medical University, Chongqing, China.
authors.forename: H
authors.initials: H
authors.lastname: Quan
authors.affiliation: The Second Affiliated Hospital and the Key Laboratory of Molecular Biology of Infectious Diseases designated by the Chinese Ministry of Education, Chongqing Medical University, Chongqing, China.
authors.forename: F
authors.initials: F
authors.lastname: Zhou
authors.affiliation: The Second Affiliated Hospital and the Key Laboratory of Molecular Biology of Infectious Diseases designated by the Chinese Ministry of Education, Chongqing Medical University, Chongqing, China.
authors.forename: D
authors.initials: D
authors.lastname: Nie
authors.affiliation: The Second Affiliated Hospital and the Key Laboratory of Molecular Biology of Infectious Diseases designated by the Chinese Ministry of Education, Chongqing Medical University, Chongqing, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Chen
authors.affiliation: The Second Affiliated Hospital and the Key Laboratory of Molecular Biology of Infectious Diseases designated by the Chinese Ministry of Education, Chongqing Medical University, Chongqing, China.
authors.forename: X
authors.initials: X
authors.lastname: Cai
authors.affiliation: The Second Affiliated Hospital and the Key Laboratory of Molecular Biology of Infectious Diseases designated by the Chinese Ministry of Education, Chongqing Medical University, Chongqing, China.
authors.forename: X
authors.initials: X
authors.lastname: Shan
authors.affiliation: The Second Affiliated Hospital and the Key Laboratory of Molecular Biology of Infectious Diseases designated by the Chinese Ministry of Education, Chongqing Medical University, Chongqing, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: The Second Affiliated Hospital and the Key Laboratory of Molecular Biology of Infectious Diseases designated by the Chinese Ministry of Education, Chongqing Medical University, Chongqing, China.
authors.forename: K
authors.initials: K
authors.lastname: Chen
authors.affiliation: The Second Affiliated Hospital and the Key Laboratory of Molecular Biology of Infectious Diseases designated by the Chinese Ministry of Education, Chongqing Medical University, Chongqing, China.
authors.forename: A
authors.initials: A
authors.lastname: Huang
authors.affiliation: The Second Affiliated Hospital and the Key Laboratory of Molecular Biology of Infectious Diseases designated by the Chinese Ministry of Education, Chongqing Medical University, Chongqing, China.
authors.forename: S
authors.initials: S
authors.lastname: Li
authors.affiliation: The Second Affiliated Hospital and the Key Laboratory of Molecular Biology of Infectious Diseases designated by the Chinese Ministry of Education, Chongqing Medical University, Chongqing, China.
authors.forename: N
authors.initials: N
authors.lastname: Tang
mesh_terms: D000107:Acetylation; D000818:Animals; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D000077209:Decitabine; D004195:Disease Models, Animal; D044127:Epigenesis, Genetic / Q000187:drug effects; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D020868:Gene Silencing; D006657:Histones / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics*; D008113:Liver Neoplasms / Q000235:genetics* / Q000473:pathology; D008565:Membrane Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic; D047368:Tumor Burden / Q000235:genetics; D014758:Viral Core Proteins / Q000378:metabolism*; D051153:Wnt Proteins / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays; D051176:beta Catenin / Q000378:metabolism; D000094742:Secreted Frizzled-Related Proteins
chemical_list: D001374:Azacitidine; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D000077209:Decitabine; D006657:Histones; D006877:Hydroxamic Acids; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D014758:Viral Core Proteins; D051153:Wnt Proteins; D051176:beta Catenin; C117636:SFRP1 protein, human; D000094742:Secreted Frizzled-Related Proteins; C069130:nucleocapsid protein, Hepatitis C virus; C012589:trichostatin A; C000619380:DNMT1 protein, human