Functional Analysis Of Microrna-219-2-3p In Gastric Cancer And Its Regulation By DNA Methylation

ObjectiveGastric cancer is the most frequent gastrointestinal tumor in adults andis the most lethal form of human cancer. Despite of the improvements intreatments, the underlying mechanism of gastric carcinogenesis is not wellknown. In our previous study, DNA methylation analysis on miRNomic chiphelps us to find14methylation related microRNAs. The miR-219-2-3p wasthe one of them. To further explore the function of the miR-219-2-3p and themethylation regulation, we conducted the following study.MethodsQuantitative RT-PCR was employed to investigate the level ofmiR-219-2-3p in gastric cancer (GC) tissues (n=113) and their matchedadjacent normal tissues (n=113). In vitro cell proliferation, apoptosis assays,cell migration, and invasion assays were performed to elucidate biologicaleffects of miR-219-2-3p. Since silencing of miRNA by promoter CpG islandmethylation may be an important mechanism in tumorgenesis, GC cells weretreated with5-aza-2’-deoxycytidine and trichostatin A, and expressionchanges of miR-219-2-3p were subsequently examined by quantitativeRT-PCR. Finally, the methylation status of CpG island upstream ofmiR-219-2-3p was analyzed by methylation-specific PCR in GC tissues(n=22). ResultmiR-219-2-3p was down-regulated in GC and cell lines. In addition, theexperiments documented the lower expression of miR-219-2-3p in GCspecimens with higher grade and later stage tumors. Meanwhile,miR-219-2-3p exerted antiproliferative, proapoptotic, and antimetastaticroles and reduced levels of p-ERK1/2in GC cells. Furthermore,5-aza-2’-deoxycytidine and trichostatin A increased the expression (~2fold)of miR-219-2-3p in GC cells. By methylation-specific PCR, DNAmethylation in the upstream region of miR-219-2-3p was detected in bothadjacent normal tissues and cancer tissues. As expected, the methylationlevel was considerably higher in the miR-219-2-3p down-regulated groupthan up-regulated group.ConclusionmiR-219-2-3p is potentially involved in gastric cancer progression andmetastasis by regulating ERK1/2-related signal pathways, which mayprovide a novel therapeutic strategy for treatment of gastric cancer.Methylation mechanism may be involved in modulating the expression levelof miR-219-2-3p in gastric cancer.