miR-132 suppresses the migration and invasion of lung cancer cells by blocking USP9X-induced epithelial-mesenchymal transition.

miR-132, a microRNA, has been reported to be down-regulated in several human cancers and is related with tumor progression; however, its function in non-small cell lung cancer (NSCLC) progression remains unclear. This study aimed to investigate the putative role of miR-132 in the metastasis of NSCLC. We determined the function of miR-132 in the migration and invasion of a NSCLC cell line in vitro using a miR-132 inhibitor and mimic. Our results showed overexpression of miR-132 significantly inhibited the migration and invasion of NSCLC cells in vitro. We then identified USP9X as a potential target of miR-132, and demonstrated miR-132 could regulate the expression of USP9X at both the mRNA and protein level. miR-132 could directly bind to the 3' untranslated region (3'-UTR) of USP9X. Inhibition of USP9X by its inhibitor WP1130 reduced the migration and invasion of NSCLC cells. Furthermore, USP9X inhibition also reversed the increased migration and invasion mediated by miR-132 inhibition. We found USP9X inhibition up-regulated expression of the epithelial-mesenchymal transition (EMT) marker E-cadherin, but down-regulated vimentin expression. A similar effect was seen with miR-132 overexpression, while the opposite effect occurred with miR-132 knockdown. USP9X inhibition reversed the miR-132 inhibitor-induced vimentin up-regulation and E-cadherin down-regulation. Taken together, these results indicate miR-132 prohibits the migration and invasion of NSCLC cells via targeting USP9X-induced EMT. Our data provides further evidence for the critical role of miR-132 and USP9X in regulating cell invasion and migration of NSCLC.