Overexpressed miR-301a promotes cell proliferation and invasion by targeting RUNX3 in gastric cancer

MicroRNAs can promote or suppress the evolution of malignant behaviors by regulating multiple targets. We aimed to determine the expression of miR-301a recently screened in gastric cancer, to investigate the biological effects of miR-301a and to identify the specific miR-301a target gene. Quantitative real-time RT-PCR was used to test miR-301a expression. Functional effects were explored by a water-soluble tetrazolium salt assay, a colony formation assay in soft agar, a migration assay, an invasion assay and cytometry used to determine apoptosis and cell cycle. Nude mice were inoculated subcutaneously by retrovirus-mediated stably expressed SGC-7901 cells. The target gene was determined by bioinformatic algorithms, dual luciferase reporter assay and Western blot. Firstly, we found that miR-301a was significantly upregulated both in cells and tissues of gastric cancer. The expression level of miR-301a was inversely correlated with tumor differentiation of gastric cancer tissues. Secondly, miR-301a promoted cell growth, soft agar clonogenicity, migration, invasion, and decreased cell apoptosis induced by cisplatin in vitro, while blockage of miR-301a reduced the percentage of G2/M phase cells via flow cytometry in gastric cancer cells. Ectopic expression of miR-301a enhanced the subcutaneous tumorigenesis in vivo. Finally, miR-301a directly downregulated RUNX3 expression post-transcriptionally in gastric cancer. Our results demonstrate that miR-301a plays important roles in the development of gastric cancer.