MicroRNA-9 inhibits gastric cancer cell proliferation and migration by targeting neuropilin-1

Gastric cancer (GC) is a global health problem with poor clinical outcomes. The mechanism of its development and progression remains largely unclear. The present study investigated the role of microRNA-9 (miR-9-5p) in the development and progression of GC. Overexpression of miR-9-5p led to reduced expression of neuropilin-1 (NRP-1) in GC cells. Dual-luciferase reporter assay results indicated that miR-9-5p directly targeted NRP-1. Furthermore, overexpression of miR-9-5p in GC cells increased the expression of mesenchymal markers, N-cadherin and vimentin, and decreased the expression of epithelial markers, E-cadherin and β-catenin. Overexpression of miR-9-5p inhibited GC cell proliferation, migration and invasion, and increased the sensitivity of GC cells to the anti-cancer drug cisplatin. By contrast, the opposite effects were observed in GC cells following downregulation of miR-9-5p. Taken together, the present findings suggested that miR-9-5p suppressed NRP-1 expression and inhibited GC cell proliferation and invasion. In addition, miR-9-5p overexpression attenuated GC cell resistance to anti-cancer drugs, which highlighted the potential of miR-9-5p as a target for the treatment of GC.