ObjectiveTo investigate the effect of up-regulation of microRNA-31(miR-31) on the biological behaviour in AGS cell of gastric cancer and on the expression of liver receptor homolog-1(LRH-1), and to analyze the possible mechanisms of miR-31 on initiation and development of gastric cancer. MethodsAGS cells were divided into 3 groups, receiving miR-31 transfection(MT group), empty liposomes transfection(NC group), and treatment of PBS (BC group). Then the cells' proliferation was determined by cell counting kit-8(CCK-8), the apoptosis situation was determined by flow cytometer, the migration was determined by Transwell test, the expression of LRH-1 protein was tested by Western blot method, and the target of miR-31 was tested by luciferase reporter assay. ResultsThe cell's proliferation results showed that the mean of A450 value in MT, NC, and BC groups were 1.31, 2.26, and 2.14 respectively on the 4 days after transfection, which lower in MT group(P<0.01).Results of flow cytometer experiment showed that the mean of apoptosis ratio of MT, NC, and BC groups were 39.5%, 9.3%, and 10.0% respectively, the mean of proportion of cell in G1+S stage were 92.54%, 73.23%, and 74.58% respectively, which both lower in MT group (P<0.05).Results of Transwell experiment showed that the mean of number of migrated cells in MT group was lower (P<0.05).Results of Western blot experiment demonstrated that the expression level of LRH-1 protein in MT group was lower than those of BC group and NC group(P<0.01). ConclusionsUp-regulation of miR-31 can obviously inhibit the proliferation of AGS cell, promoting its apoptosis and depressing its migration ability. On the other side, the up-regulation of miR-31 can also inhibit the expression level of LRH-1 protein, which indirectly induces the inhibition of proliferation of AGS cell. So miR-31 may be an important regulator in the initiation and development of gastric cancer through regulating LRH-1 gene.