Abstract: Objective To investigate the effect of small interfering RNA(siRNA) targeting migrationinducing protein 7(Mig-7) gene on the invasion and migration abilities of human gastric cancer cells MKN45, and the underlying mechanism. Methods The chemically synthetic siRNA targeting Mig-7 gene was transfected into MKN45 cells via LipofectamineTM 2000. The gene silencing effect of siRNA targeting Mig-7 was determined by real-time PCR and Western blot at mRNA and protein levels, respectively. Cell proliferation was examined by MTT assay. The cell invasion and migration abilities were determined by Transwell experiment. The protein levels of matrix metalloproteinase-2(MMP-2) and MMP-9 were analyzed by Western blot. Results After transfection of chemically synthetic siRNA into MKN45 cells, the mRNA and protein levels of Mig-7 were significantly reduced by (80±2.91)% and (89.1±2.67)%, respectively. No statistical difference was observed among each group in the growth rates in vitro (P>0.05). Compared with the control groups, the knockdown of Mig-7 in MKN45 cells resulted in significant reduction of cell invasion and migration abilities (P<0.05); down-regulation of Mig-7 in MKN45 cells also reduced the expression of MMP-2 protein (P<0.05). But there was no statistical difference in the expression of MMP-9protein among each group (P>0.05). Conclusion The invasion and migration abilities of gastric cancer cells MKN45 are inhibited by reducing the expression of Mig-7 which might be mediated by downregulating the expression of MMP-2 protein.