title: Hepatitis virus infection affects DNA methylation in mice with humanized livers.
abstract: OBJECTIVE
  Cells of tumors associated with chronic inflammation frequently have altered patterns of DNA methylation, including hepatocellular carcinomas. Chronic hepatitis has also been associated with aberrant DNA methylation, but little is known about their relationship.
  
  
  METHODS
  Pyrosequencing was used to determine the methylation status of cultured Huh7.5.1 hepatoma cells after hepatitis C virus (HCV) infection. We also studied mice with severe combined immunodeficiency carrying the urokinase-type plasminogen activator transgene controlled by an albumin promoter (urokinase-type plasminogen activator/severe combined immunodeficient mice), in which up to 85% of hepatocytes were replaced by human hepatocytes (chimeric mice). Mice were given intravenous injections of hepatitis B virus (HBV) or HCV, liver tissues were collected, and DNA methylation profiles were determined at different time points after infection. We also compared methylation patterns between paired samples of hepatocellular carcinomas and adjacent nontumor liver tissues from patients.
  
  
  RESULTS
  No reproducible changes in DNA methylation were observed after infection of Huh7.5.1 cells with HCV. Livers from HBV- and HCV-infected mice had genome-wide, time-dependent changes in DNA methylation, compared with uninfected urokinase-type plasminogen activator/severe combined immunodeficient mice. There were changes in 160 ± 63 genes in HBV-infected and 237 ± 110 genes in HCV-infected mice. Methylation of 149 common genes increased in HBV- and HCV-infected mice; methylation of some of these genes also increased in hepatocellular carcinoma samples from patients compared with nontumor tissues. Expression of Ifng, which is expressed by natural killer cells, increased significantly in chimeric livers, in concordance with induction of DNA methylation, after infection with HBV or HCV. Induction of Ifng was reduced after administration of an inhibitor of natural killer cell function (anti-asialo GM1).
  
  
  CONCLUSIONS
  In chimeric mice with humanized livers, infection with HBV and HCV appears to activate a natural kill cell-dependent innate immune response. This contributes to the induction and accumulation of aberrant DNA methylation in human hepatocytes.
authors.affiliation: Division of Epigenomics, Aichi Cancer Center, Nagoya, Japan; Division of Molecular Oncology, Aichi Cancer Center, Nagoya, Japan; Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Okamoto
authors.affiliation: Division of Epigenomics, Aichi Cancer Center, Nagoya, Japan; Division of Oncological Pathology, Aichi Cancer Center, Nagoya, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Shinjo
authors.affiliation: Department of Gastroenterological Surgery, Aichi Cancer Center, Nagoya, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Shimizu
authors.affiliation: Department of Gastroenterological Surgery, Aichi Cancer Center, Nagoya, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Sano
authors.affiliation: Department of Gastroenterology, Aichi Cancer Center, Nagoya, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Yamao
authors.affiliation: Department of General Surgery, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Wentao
authors.initials: W
authors.lastname: Gao
authors.affiliation: Division of Molecular Oncology, Aichi Cancer Center, Nagoya, Japan.
authors.forename: Makiko
authors.initials: M
authors.lastname: Fujii
authors.affiliation: Division of Molecular Oncology, Aichi Cancer Center, Nagoya, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Osada
authors.affiliation: Division of Molecular Oncology, Aichi Cancer Center, Nagoya, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Sekido
authors.affiliation: Department of Virology and Liver Unit, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Shuko
authors.initials: S
authors.lastname: Murakami
authors.affiliation: Department of Virology and Liver Unit, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Tanaka
authors.affiliation: Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Joh
authors.affiliation: Department of Experimental Pathology and Tumor Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Sato
authors.affiliation: Department of Experimental Pathology and Tumor Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Takahashi
authors.affiliation: Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: Takaji
authors.initials: T
authors.lastname: Wakita
authors.affiliation: Cancer Epigenetics Program, Shanghai Cancer Institute, Shanghai Jiaotong University, Shanghai, China.
authors.forename: Jingde
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania.
authors.forename: Jean-Pierre J
authors.initials: JP
authors.lastname: Issa
authors.affiliation: Division of Epigenomics, Aichi Cancer Center, Nagoya, Japan; Division of Molecular Oncology, Aichi Cancer Center, Nagoya, Japan; Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Saitama, Japan. Electronic address: ykondo@aichi-cc.jp.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Kondo
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000276:immunology / Q000821:virology; D045744:Cell Line, Tumor; D002648:Child; D002675:Child, Preschool; D046528:Chimerism; D018899:CpG Islands; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D005260:Female; D006509:Hepatitis B / Q000150:complications / Q000235:genetics* / Q000276:immunology; D006526:Hepatitis C / Q000150:complications / Q000235:genetics* / Q000276:immunology; D006801:Humans; D007113:Immunity, Innate; D007694:Killer Cells, Natural / Q000276:immunology; D008099:Liver / Q000276:immunology / Q000821:virology*; D008113:Liver Neoplasms / Q000235:genetics / Q000276:immunology / Q000821:virology; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D016513:Mice, SCID; D020411:Oligonucleotide Array Sequence Analysis; D017422:Sequence Analysis, DNA; D055815:Young Adult
keywords: ESR1; Epigenetic; Gene Regulation; HBV; HBx; HCC; HCV; HOXA6; IFN; Inflammatory Response; Liver Cancer; MCAM; NK; PCNA; RASSF1A; ROS; Ras association domain family 1 isoform A; SCID; estrogen receptor 1; hepatitis B virus; hepatitis B virus X; hepatitis C virus; hepatocellular carcinoma; homeobox A6; interferon; methylated CpG island amplification microarray; natural killer; proliferating cell nuclear antigen; reactive oxygen species; severe combined immunodeficient