miR-340 alleviates chemoresistance of osteosarcoma cells by targeting ZEB1.

Chemoresistance during treatment of osteosarcoma (OS) is attracting more and more attention as the main clinical obstacle. The purpose of this study was to elucidate the role of miR-340 in chemoresistance of OS. Plasmid construction and transfection, miRNA arrays, PCR analyses, and western blot analysis, as well as MTT, apoptosis, and luciferase assays were carried out in MG-63 cells and MG-63/cisplatin (DDP)-resistant cells. The results showed that miR-340 was downregulated in OS tissues and drug-resistant OS cells. Moreover, a negative correlation was observed between miR-340 and ZEB1 expression in OS tissues. Forced expression of miR-340 in drug-resistant OS cells significantly reduced multidrug resistance-1 and P-gp expression. Overexpression of miR-340 enhanced sensitivity to DDP by inhibiting viability and promoting apoptosis. The luciferase assay and western blot analysis identified ZEB1 as a direct target of miR-340, and miR-340 negatively regulated ZEB1 expression. Ectopic expression of ZEB1 reversed the effects of miR-340 on P-gp expression, cell viability, and apoptosis. miR-340 alleviated chemoresistance of OS cells by targeting ZEB1. Our results indicate that targeting miR-340 may be a potential therapeutic approach to treat drug-resistant OS.