MicroRNA-146a negatively regulates PTGS2 expression induced by Helicobacter pylori in human gastric epithelial cells

Helicobacter pylori is a major human pathogenic bacterium in the gastric mucosa, but to date the regulatory mechanism of the H. pylori-induced inflammatory response is not clear. MicroRNAs have recently emerged as key post-transcriptional regulators of gene expression. We have previously reported that miR-146a negatively regulates the H. pylori-induced inflammatory response, but its molecular mechanism is just beginning to be explored. Our aim was to further explore the key targets of miR-146a and its role of regulation in H. pylori infection. The potential targets of miR-146a were screened through bioinformatic approaches and identified by luciferase reporter assays and green fluorescent protein (GFP) repression experiments. Overexpression and inhibition of miR-146a were used to examine the impacts of miR-146a on its target gene, determined by quantitative real-time polymerase chain reaction (PCR) and western blotting. Prostaglandin endoperoxide synthase 2 (PTGS2) is a target gene of miR-146a, and miR-146a decreased PTGS2 expression by degradation of its mRNA, suggesting that the miR-146a-mediated inhibition is a post-transcriptional event. Furthermore, miR-146a and PTGS2 were significantly increased in H. pylori -infected human gastric epithelial cells. Overexpression of miR-146a resulted in significantly reduced PTGS2 production induced by H. pylori infection. These results suggest that miR-146a may be involved in negatively regulating H. pylori-induced PTGS2 expression in human gastric epithelial cells.