This study intended to explore the molecular mechanism of RUNX3 in inhibiting the process of migration and proliferation of gastric cancer (GC) cells.

The overexpressed plasmids of RUNX3 and the interfering siRNA of RUNX3 were transfected into GC cells. Then, qRT-PCR and western blot were performed to identify the expression level of RUNX3 and miR-182 in tumors and adjacent tissues respectively. ChIP and luciferase assay were performed to detect the relationship between RUNX3 and miR-182 as well as miR-182 and HOXA9. Furthermore, EdU assay were used to investigate the proliferation of GC cells, Transwell assay and wound healing assay were utilized to assess cell metastasis. Xenograft mouse model was set to evaluate the proliferation in vivo.

The results of qRT-PCR and western blot indicated that RUNX3 could regulate the expression of miR-182. RUNX3 can be straightly interacted with the promoter region of miR-182 in accordance with the results of ChIP. Luciferase assay revealed that HOXA9 was the direct target gene of miR-182. In addition, EdU proliferation, wound healing assay and transwell assay showed that miR-182 mimics and HOXA9 siRNA could inhibit the ability of cells proliferation, migration and invasion. The findings of in vivo experiments strongly supported the view that miR-182/HOXA9 was involved in the process of RUNX3-mediated GC tumor growth.

RUNX3 could impede the ability of GC cells proliferation, migration and invasion by modulating miR-182/HOXA9 pathway.