Identification of aberrant overexpression of long non-coding RNA MALAT1 and role as a regulatory microRNA in liver cancer

MALAT1 is deregulated in various cancers. The underlying mechanisms of MALA T1-mediated tumorigenesis are unclear. We found that MALAT1 was highly overexpressed and its overexpression was significantly associated with poor prognosis of liver cancer patients analyzed from the TCGA Liver Hepatocellular Carcinoma and Gene Expression Omnibus databases of the National Center for Biotechnology Information. Microarray analysis to identify the miRNAs deregulated by silencing MALAT1 in two liver cancer cell lines, HepG2 and Hep3B, revealed the common deregulation of 16 miRNAs including miR-574 and miR-20b in both cell lines. The predicted targets of miR-574 and miR-20b were cancer-related pathways including the RAS, MAPK and Wnt/β-catenin pathways. Aberrant expression of MALAT1 might contribute to liver cancer tumorigenesis by deregulation of cancer-associated miRNAs.