Chronic liver inflammation modifies DNA methylation at the precancerous stage of murine hepatocarcinogenesis.
Chronic liver inflammation precedes the majority of hepatocellular carcinomas (HCC). Here, we explore the connection between chronic inflammation and DNA methylation in the liver at the late precancerous stages of HCC development in Mdr2(-/-) (Mdr2/Abcb4-knockout) mice, a model of inflammation-mediated HCC. Using methylated DNA immunoprecipitation followed by hybridization with "CpG islands" (CGIs) microarrays, we found specific CGIs in 76 genes which were hypermethylated in the Mdr2(-/-) liver compared to age-matched healthy controls. The observed hypermethylation resulted mainly from an age-dependent decrease of methylation of the specific CGIs in control livers with no decrease in mutant mice. Chronic inflammation did not change global levels of DNA methylation in Mdr2(-/-) liver, but caused a 2-fold decrease of the global 5-hydroxymethylcytosine level in mutants compared to controls. Liver cell fractionation revealed, that the relative hypermethylation of specific CGIs in Mdr2(-/-) livers affected either hepatocyte, or non-hepatocyte, or both fractions without a correlation between changes of gene methylation and expression. Our findings demonstrate that chronic liver inflammation causes hypermethylation of specific CGIs, which may affect both hepatocytes and non-hepatocyte liver cells. These changes may serve as useful markers of an increased regenerative activity and of a late precancerous stage in the chronically inflamed liver.
The Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
Evgeniy
E
Stoyanov
Department of Developmental Biology and Cancer Research, Faculty of Medicine, The Hebrew University, Jerusalem, Israel.
Guy
G
Ludwig
The Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
Lina
L
Mizrahi
The Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
Devorah
D
Olam
The Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
Temima
T
Schnitzer-Perlman
Institute of Experimental Immunology and Hepatology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Elena
E
Tasika
Institute of Experimental Immunology and Hepatology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Gabriele
G
Sass
Institute of Experimental Immunology and Hepatology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Gisa
G
Tiegs
Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, and Veterans Affairs Medical Center, Decatur, GA, USA.
Yong
Y
Jiang
Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, and Veterans Affairs Medical Center, Decatur, GA, USA.
Ting
T
Nie
Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, and Veterans Affairs Medical Center, Decatur, GA, USA.
James
J
Kohler
Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, and Veterans Affairs Medical Center, Decatur, GA, USA.
Raymond F
RF
Schinazi
Department of Radiation Oncology and The Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USA.
Paula M
PM
Vertino
Department of Developmental Biology and Cancer Research, Faculty of Medicine, The Hebrew University, Jerusalem, Israel.
Howard
H
Cedar
The Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
Eithan
E
Galun
The Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
Daniel
D
Goldenberg
D018435:ATP Binding Cassette Transporter, Subfamily B / Q000502:physiology*; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000209:etiology* / Q000473:pathology; D002478:Cells, Cultured; D002908:Chronic Disease; D018899:CpG Islands; D019175:DNA Methylation; D020869:Gene Expression Profiling; D022781:Hepatocytes / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007249:Inflammation / Q000150:complications* / Q000473:pathology; D008099:Liver / Q000378:metabolism / Q000473:pathology*; D008113:Liver Neoplasms / Q000209:etiology* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D011230:Precancerous Conditions / Q000209:etiology* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000097202:ATP-Binding Cassette Sub-Family B Member 4
D018435:ATP Binding Cassette Transporter, Subfamily B; D012333:RNA, Messenger; D000097202:ATP-Binding Cassette Sub-Family B Member 4
5-hydroxymethylcytosine; DNA methylation; Mdr2 (Abcb4); hepatocellular carcinoma; mtDNA deletion