Affiliation:
1. Department of Pathology Keio University School of Medicine Tokyo Japan
2. Fundamental Innovative Oncology Core Center National Cancer Center Research Institute Tokyo Japan
3. Department of Diagnostic Pathology National Cancer Center Hospital Tokyo Japan
Abstract
AbstractAimThe aim of this study was to clarify the significance of DNA methylation alterations of cryptogenic hepatocellular carcinomas (HCCs).MethodsUsing the Infinium assay, we performed genome‐wide DNA methylation analysis of 250 liver tissue samples, including noncancerous liver tissue (U‐N) and corresponding cancerous tissue (U‐T) from patients with cryptogenic HCC without a history of excessive alcohol use and hepatitis virus infection, and whose U‐N samples showed no remarkable histological features (no microscopic evidence of simple steatosis, any form of hepatitis including nonalcoholic steatohepatitis, or liver cirrhosis).ResultsWe identified 3272 probes that showed significant differences of DNA methylation levels between U‐N and normal liver tissue samples from patients without HCC, indicating that a distinct DNA methylation profile had already been established at the precancerous U‐N stage. U‐Ns have a DNA methylation profile differing from that of noncancerous liver tissue of patients with nonalcoholic steatohepatitis‐related, viral hepatitis‐related, and alcoholic liver disease‐related HCCs. Such DNA methylation alterations in U‐Ns were inherited by U‐Ts. The U‐Ns showed DNA methylation alteration of ADCY5, resulting in alteration of its mRNA expression, whereas noncancerous liver tissue of patients with nonalcoholic steatohepatitis‐, viral hepatitis‐, or alcoholic liver disease‐related HCCs did not. DNA methylation levels of MICAL2 and PLEKHG2 in U‐Ts were correlated with larger tumor diameter and portal vein involvement, respectively.ConclusionsU‐N‐specific DNA hypermethylation of ADCY5 may have significance, even from the precancerous stage in liver showing no remarkable histological features. DNA hypomethylation of MICAL2 and PLEKHG2 may determine the clinicopathological features of cryptogenic HCC.
Funder
Japan Agency for Medical Research and Development
Subject
Infectious Diseases,Hepatology