Regulation of MYO18B mRNA by a network of C19MC miRNA-520G, IFN-γ, CEBPB, p53 and bFGF in hepatocellular carcinoma

MYO18B has been proposed to contribute to the progression of hepatocellular carcinoma (HCC). However, the signals that govern MYO18B transcription are not known. Here we show that, a network of C19MC miRNA-520G, IFN-γ, CEBPB and p53 transcriptional-defects promote MYO18B mRNA expression in HCCs. IFN-γ by itself suppresses MYO18B transcription, but promotes it when miRNA-520G is stably overexpressed. Similarly, CEBPB-liver-enriched activator protein (LAP) isoform overexpression suppresses MYO18B transcription but promotes transcription when the cells are treated with IFN-γ. Furthermore, miR-520G together with mutant-p53 promotes MYO18B transcription. Conversely, bFGF suppresses MYO18B mRNA irrespective of CEBPB, miR-520G overexpression or IFN-γ treatment. Finally high MYO18B expression reflects poor prognosis while high MYL5 or MYO1B expression reflects better survival of HCC patients. Thus, we identified a network of positive and negative regulators of MYO18B mRNA expression which reflects the survival of HCC patients.