Upregulation of microRNA-524-5p enhances the cisplatin sensitivity of gastric cancer cells by modulating proliferation and metastasis via targeting SOX9.

Cisplatin-based chemotherapy is the most commonly used treatment regimen for gastric cancer (GC), however, the resistance to cisplatin represents the key limitation for the therapeutic efficacy. Aberrant expression of MiR-524-5p appears to be involves in tumorigenesis and chemoresistance. However, the mechanism by which miR-524-5p mediates effects of cisplatin treatment in GC remains poorly understood. Expressions of MiR-524-5p was detected in GC tissues and cell lines by qRT-PCR. Cell proliferation was observed by MTT assay; Cell migration was detected by transwell migration and invasion assay. The targeting protein of miR-524-5p was identified by luciferase reporter assay and western blot. We found that downregulation of miR-524-5p in GC tissues and cell lines. SC-M1 and AZ521 cells resistant to cisplatin expressed low levels of miR-524-5p in comparison to the sensitive parental cells. Overexpression of miR-524-5p expression in SC-M1 and AZ521 cells inhibited cell proliferation, migration, and invasion, and conferred sensitivity to cisplatin-resistant GC cells. Subsequently, we identified SOX9 as a functional target protein of miR-524-5p and found that SOX9 overexpression could counteracts the chemosensitizing effects of miR-524-5p. These results provide novel insight into the regulation of GC tumorigenesis and progression by miRNAs. Restoration of miR-524-5p may have therapeutic potential against GC.