Authors: Braconi C; Kogure T; Valeri N; Huang N; Nuovo G; Costinean S; Negrini M; Miotto E; Croce CM; Patel T
Abstract: The human genome is replete with long non-coding RNAs (lncRNA), many of which are transcribed and likely to have a functional role. Microarray analysis of >23,000 lncRNAs revealed downregulation of 712 (~3%) lncRNA in malignant hepatocytes, among which maternally expressed gene 3 (MEG3) was downregulated by 210-fold relative to expression in non-malignant hepatocytes. MEG3 expression was markedly reduced in four human hepatocellular cancer (HCC) cell lines compared with normal hepatocytes by real-time PCR. RNA in situ hybridization showed intense cytoplasmic expression of MEG3 in non-neoplastic liver with absent or very weak expression in HCC tissues. Enforced expression of MEG3 in HCC cells significantly decreased both anchorage-dependent and -independent cell growth, and induced apoptosis. MEG3 promoter hypermethylation was identified by methylation-specific PCR and MEG3 expression was increased with inhibition of methylation with either 5-Aza-2-Deoxycytidine, or siRNA to DNA Methyltransferase (DNMT) 1 and 3b in HCC cells. MiRNA-dependent regulation of MEG3 expression was studied by evaluating the involvement of miR-29, which can modulate DNMT 1 and 3. Overexpression of mir-29a increased expression of MEG3. GTL2, the murine homolog of MEG3, was reduced in liver tissues from hepatocyte-specific miR-29a/b1 knock-out mice compared with wild-type controls. These data show that methylation-dependent tissue-specific regulation of the lncRNA MEG3 by miR-29a may contribute to HCC growth and highlight the inter-relationship between two classes of non-coding RNA, miRNAs and lncRNAs, and epigenetic regulation of gene expression.
Keywords: Carcinoma, Hepatocellular/*genetics; DNA Methylation; Epigenesis, Genetic; *Gene Expression Regulation, Neoplastic; Humans; Liver Neoplasms/*genetics; MicroRNAs/*physiology; Organ Specificity; Proteins/*genetics; RNA, Long Untranslated; RNA, Untranslated/*genetics
Journal: Oncogene Volume: 30 Issue: 47 Pages: 4750-6 Date: June 1, 2011 PMID: 21625215 |
Braconi C, Kogure T, Valeri N, Huang N, Nuovo G, Costinean S, Negrini M, Miotto E, Croce CM, Patel T (2011) microRNA-29 can regulate expression of the long non-coding RNA gene MEG3 in hepatocellular cancer. Oncogene 30: 4750-6.
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