A microRNA-4516 inhibitor sensitizes chemo-resistant gastric cancer cells to chemotherapy by upregulating ING4

Abstract

Objective MicroRNA (miRNA) is an important factor in the regulation of gene transcription. This study was aimed at investigating the role of miR-4516 in the chemoresistance of gastric cancer cells. Methods miR-4516 expression levels were measured in gastric cancer cell line SGC7901 and in 5-fluorouracil (5-FU)resistant SGC7901 cells (SGC7901/5-FU) via microarray analysis and RT-PCR. A miR-4516 inhibitor and negative controls were transfected into SGC7901/5-FU cells. A miR-4516 mimic and negative controls were transfected into SGC7901 cells. CCK8 and flow-cytometric assays were performed to evaluate the sensitivity of SGC7901/5-FU cells to 5-FU. Western blot experiments detected the expression of Bcl-2, Bax, Caspase-3, P-gp and ING4 protein. Results Additionally, ING4 was demonstrated to be downregulated in SGC7901/5-FU cells and inversely correlated with miR-4516 expression. Rescue experiments revealed that overexpression of ING4 attenuated the inhibitory effects of miR-4516 on the proliferation of gastric cancer cells. ING4 was predicted to be a potential target of miR-4516. Synergism of the inhibitory effects correlated with a reduction in the expression of the anti-apoptotic protein Bcl-2 and the drug resistance-related protein P-gp as well as strong expression of apoptosis-related proteins(Bax, Caspase-3). Thus, a miR-4516 inhibitor sensitized gastric cancer SGC7901/5-FU cells to 5-FU by enhancing apoptosis. We then corroborated these results with in vivo experiments. Conclusion We found that miR-4516 might be a potential therapeutic target in chemo-resistant gastric cancer.