Expression and function of miRNAs in gastric carcinoma

To clarify the role of micro (mi) RNAs in gastric carcinogenesis, we studied the expression and function of miRNAs in gastric carcinoma (GC) cells. Initially, we performed microarray analysis using total RNA from three human GC cell lines and non-cancerous gastric tissue. Among the down-regulated miRNAs in GC cells,miR-212 expression was decreased in all eight GC cell lines examined and a significant decrease of miR-212 expression in human primary GC tissues was also observed in 6 of 11 cases. Transfection of the precursor miR-212 molecule induced decreased growth of a GC cell line. Using three different databases, methyl-CpG-binding protein MeCP2 was postulated to be a target of miR-212. As seen on reporter assaying, miR-212 repressed the construct with the MECP2 3'-UTR. Ectopic expression of miR-212 repressed expression of the MeCP2 protein,but not the MECP2 mRNA level. These data suggest that down-regulation of miR-212 may be related to gastric carcinogenesis through its target genes, such as MECP2. We used three GC cell lines (MKN7, MKN74 and NUGC4) and one non-cancerous gastric tissue. miRNA microarray analysis was performed with mirVana miRNA Bioarrays V1 (Ambion) according to the manufacturer’s instructions.