MicroRNA-146a promotes apoptosis of gastric cancer SGC-7901 cells by targeting TAK1

AIM: To explore the effect of microRNA-146a (miR-146a) on apoptosis of human gastric cancer SGC-7901 cells and the underluing mechanism. METHODS: miR-146a mimic (up-regulated miR-146a expression) and miR-146a inhibitor (down-regulated miR-146a expression) were transfected into the SGC-7901 cells by liposome method. At the same time, miRNA nonsense sequence transfection group as the negative control group (NC group) was set up. RT-qPCR was used to evaluate the levels of miR-146a in the SGC-7901 cells after transfection. The effects of miR-146a on the cell apoptosis and growth were assessed by flow cytometry analysis and CCK-8 assay, respectively. The effect of over-expression or knockdown of miR-146a on transforming growth factor-β-activated kinase 1 (TAK1)/nuclear factor-kappa B (NF-κB) signaling was evaluated by RT-qPCR and Western blot. RESULTS: miR-146a modulated apoptosis of SGC-7901 cells. Over-expression of miR-146a significantly increased apoptosis, whereas knockdown of miR-146a inhibited the apoptosis of SGC-7901 cells. The expression of TAK1 at mRNA and protein levels was significantly decreased when miR-146a mimic was transfected into the SGC-7901 cells (P<0.05). On the contrast, the expression of TAK1 at mRNA and protein were significantly higher in miR-146a inhibitor transfection group than that in NC group (P<0.05), suggesting that miR-146a negatively regulated TAK1 expression. Moreover, knockdown of TAK1 enhanced the apoptosis of SGC-7901 cells (P<0.01), while over-expression of TAK1 inhibited the apoptosis of SGC-7901 cells(P<0.01). Additionally, both over-expression of miR-146a and knockdown of TAK1 led to a prominent increase in the expression of NF-κB inhibitor protein alpha (IκBα) and a significat decrease in B cell lymphoma-2 (Bcl-2) level in the SGC-7901 cells. CONCLUSION: miR-146a significantly promotes apoptosis of SGC-7901 cells by inhibition of NF-κB pathway via targeting TAK1.