Dataset Information

Chronic liver inflammation modifies DNA methylation at the precancerous stage of murine hepatocarcinogenesis.

ABSTRACT: 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.

SUBMITTER: Stoyanov E

PROVIDER: S-EPMC4484438 | biostudies-literature | 2015 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Chronic liver inflammation modifies DNA methylation at the precancerous stage of murine hepatocarcinogenesis.

Stoyanov Evgeniy E Ludwig Guy G Mizrahi Lina L Olam Devorah D Schnitzer-Perlman Temima T Tasika Elena E Sass Gabriele G Tiegs Gisa G Jiang Yong Y Nie Ting T Kohler James J Schinazi Raymond F RF Vertino Paula M PM Cedar Howard H Galun Eithan E Goldenberg Daniel D

Oncotarget 20150501 13

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 ...[more]

PMID: 25918251

Similar Datasets

Project description:Surgical resection is the preferred treatment for Hepatocellular carcinoma; however, it induces tumor recurrence. Our objective was to understand the molecular mechanisms linking liver regeneration under chronic-inflammation to tumorigenesis. Mdr2-knockout mice, a model of inflammation-associated cancer, underwent partial-hepatectomy which led to enhanced hepatocarcinogenesis. Yet, liver regeneration in these mice was severely attenuated. We demonstrate the activation of the DNA damage response machinery and altered genomic instability during early liver inflammatory stages resulting in hepatocyte apoptosis and cell-cycle arrest, and suggest their involvement in tumor recurrence subsequent to partial hepatectomy. We propose that under the regenerative proliferative stress induced by liver resection, the genomic unstable hepatocytes generated during chronic-inflammation, escape apoptosis and reenter the cell-cycle, triggering the enhanced tumorigenesis At present, there is a great organ shortage worldwide, thus the main treatment for Hepatocellular carcinoma (HCC) is liver resection. However, liver resection induces recurrence and mortality. In our study, we decipher, for the first time, the contribution of the DNA damage response in HCC development and recurrence, the immediate and long term effect. This is an important finding regarding the association between carcinogenesis and DNA damage response. Additionally, we demonstrate yet another link between inflammation, inducing DNA damage and genome instability, and carcinogenesis that has not been explored in the past. These results may assist in developing treatments that will reduce tumor recurrence and additionally, new prophylactic therapies during early inflammatory stages. Keywords: time course, regeneration RNA was isolated from liver samples of 9-month-old Mdr2-/- and control mice obtained on days 0 (the removed lobe), 2 and 6 following PHx. Samples of d0 were obtained from the same mice that were sacrificed on later days. As we were concerned by the variability in the KO group 6 samples were obtained for d0. All other time points and groups contained 3 samples each.

Project description:The aim of this study was to clarify the significance of DNA methylation alterations at precancerous stages of lung adenocarcinoma. Using single-CpG resolution Infinium array, genome-wide DNA methylation analysis was performed in 36 samples of normal lung tissue obtained from patients without any primary lung tumor, 145 samples of non-cancerous lung tissue (N) obtained from patients with lung adenocarcinomas, and 145 samples of tumorous tissue (T). Stepwise progression of DNA methylation alterations from normal lung tissue to non-cancerous lung tissue obtained from patients with lung adenocarcinomas, and then tumorous tissue samples, was observed at 3,270 CpG sites, suggesting that non-cancerous lung tissue obtained from patients with lung adenocarcinomas was at precancerous stages with DNA methylation alterations. At CpG sites of 2,083 genes, DNA methylation status in samples of non-cancerous lung tissue obtained from patients with lung adenocarcinomas was significantly correlated with recurrence after establishment of lung adenocarcinomas. Among such recurrence-related genes, 28 genes are normally unmethylated (average ?-values based on Infinium assay in normal lung tissue samples was less than 0.2) and their DNA hypermethylation at precancerous stages was strengthened during progression to lung adenocarcinomas (??(T-N)>0.1). Among these 28 genes, we focused on 6 for which implications in transcription regulation, apoptosis or cell adhesion had been reported. DNA hypermethylation of the ADCY5, EVX1, GFRA1, PDE9A, and TBX20 genes resulted in reduced mRNA expression in tumorous tissue samples. 5-Aza-2'-deoxycytidine treatment of lung cancer cell lines restored the mRNA expression levels of these 5 genes. Reduced mRNA expression in tumorous tissue samples was significantly correlated with tumor aggressiveness. These data suggest that DNA methylation alterations at precancerous stages determine tumor aggressiveness and outcome through silencing of specific genes.

Dataset Information

Chronic liver inflammation modifies DNA methylation at the precancerous stage of murine hepatocarcinogenesis.

Publications

Chronic liver inflammation modifies DNA methylation at the precancerous stage of murine hepatocarcinogenesis.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure