Systemes analysis of interactions between microRNAs and genes in hepatocellular carcinoma

MicroRNAs (miRNAs) are short noncoding RNAs and can regulate gene expression at the transcriptional and/or translational levels. There is mounting evidence that miRNAs play an important role in the control of the dynamics of localized gene expression. Expression profiling of miRNA in various cancers revealed that miRNA profiles could discriminate malignancies from their counter parts. In this study, to investigate the localized effect of miRNA in cancer, we analyzed gene and miRNA expressions in hepatocellular carcinoma (HCC) and surrounding nontumor tissues. Based on gene expression levels around miRNAs, we investigated how many miRNAs correlated positively/negatively in expression with genes in the vicinity. Next, the Pearson correlation coefficients were compared between the HCC and nontumor tissues. The results imply that the relationship between the intronic miRNAs and their host genes was altered in HCC, and that feedback loops including the host gene, intronic miRNA, target genes might be formed in HCC.