The regulation of miRNA expression by DNA methylation in hepatocellular carcinoma

Emerging evidences indicate that microRNAs (miRNAs) are often deregulated and have fundamental roles in hepatocellular carcinoma (HCC). However, the mechanism underlying miRNA dysregulation in HCC is still elusive. In this report, we used an integrated analysis strategy combining methylated DNA immunoprecipitation chip (MeDIP-chip) and miRNA expression microarray data to study the correlation between aberrant methylation and dysregulation of miRNA in HCC. In all, we showed that global miRNA methylation profiles were significantly different between cancerous and normal hepatocytes, and abnormal methylation was an important mechanism governing miRNA expression in HCC. MeDIP-chip was processed in cancerous hepatocytes SK-HEP-1, HepG2, MHCC97-H and normal hepatocytes PHHC-4-1, PHHC-4-2, PHHC-4-3 (3 technical repeat of PHHC-4). MiRNA microarray were processed for cancerous hepatocytes SK-HEP-1, HepG2, Hep3B, Huh7, MHCC97-H, MHCC97-L, SMMC-7721 and normal hepatocytes PHHC-1, PHHC-2, PHHC-3. Then an integrated analysis strategy combining MeDIP-chip and miRNA expression microarray [GSE20077] were used to study the correlation of aberrant DNA methylation and dysregulation of miRNAs.