MicroRNA-146a is down-regulated in gastric cancer and regulates cell proliferation and apoptosis.

Aberrant expression of microRNA-146a (miR-146a) has been reported to be involved in development and progression in various types of cancers, but its role in gastric cancer has not been fully elucidated. The purpose of this study was to investigate the levels of miR-146a expression and its function in human gastric cancer. Quantitative real-time polymerase chain reaction was used to detect the levels of miR-146a expression in gastric cancer tissue samples and cell lines. The cell growth rate of MKN-45 gastric cancer cells transfected with miR-146a mimics was examined by MTT assay. The effects of miR-146a on cell cycle and apoptosis were assessed by FACS analyses in MKN-45 cells. Thirty-six of 43 gastric cancer tissue samples (84%) showed decreased expression of miR-146a. We found low expression of miR-146a was correlated with increased tumor size (P = 0.006) and poor differentiation (P = 0.010) in gastric cancer. Overall survival time of patients with high miR-146a expression was significantly longer than that of patients with low expression of miR-146a (P = 0.011). The MTT assay showed that introduction of miR-146a inhibited cell proliferation in MKN-45 cells (P < 0.05). The proportion of apoptotic cells induced by transfection of miR-146a mimics were greater than that induced by transfection of the negative control mimics (11.9 vs. 5.9%). Our results suggested that miR-146a has potential as a novel suppressor gene in gastric cancer and its down-regulation may promote the progression of gastric cancer.