Abstract: Objective:To investigate the role and mechanism of miR-143 in the proliferation and migration of gastric cancer (GC) cells.Methods:Western blot was performed to detect the expression level of avian erythroblastosis oncogene B-3 (ERBB 3) in GC tissues,paired non-cancerous tissues, and SGC 7901GC cells. RT-qPCR was conducted to determine the mRNA and miR-143 of ERBB3 quantita-tively. Bioinformatics tools were used to predict the target gene of miR- 143 . Luciferase reporter assay was carried out to confirm the predicted target gene. Transwell and EdU assays were applied to observe the migration and proliferation of SGC7901GC cells transfect -ed with miR-143 mimics/inhibitor/NC mimics/inhibitor. Results: Compared with the expression levels of ERBB 3 and miR- 143 in the paired non cancerous tissues, the expression level of ERBB3 was upregulated and the expression level of miR-143 was downregulated in GC tissues. In the prediction of the potential target gene, miR- 143 could bind to a specific sequence of the 3′-untranslatedregions (UTR) of the mRNA of ERBB 3. This finding was supported by luciferase reporter assay results. In vitro, ERBB 3 protein expression and cell migration and proliferation were suppressed significantly in the SGC7901cells transfected with miR- 143 mimics. By contrast, these processes were remarkably enhanced when the cells were transfected with miR-143 inhibitor. Conclusion: miR- 143 can suppress the migration and proliferation of GC cells by downregulating the expression of ERBB3.