Dysregulation of microRNAs (miRNAs) expression is prevalent in human malignancy development and progression. As previously reported, miR-509-5p has been identified as a tumor suppressor in various cancers, but its role and functional mechanism in non-small lung cancer (NSCLC) remains unknown. In the present study, we found that miR-509-5p was significantly downregulated in NSCLC tissues and cell lines using Quantitative real-time PCR (qRT-PCR). In addition, overexpression of miR-509-5p markedly inhibited the proliferation, migration, invasion and phosphorylation of Akt of NSCLC cells. Moreover, we identified tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein gamma (YWHAG) as a direct target of miR-509-5p. Knockdown of YWHAG mimicked the inhibitory effects of miR-509-5p on NSCLC cells for proliferation and motility. Finally, the negative correlation between miR-509-5p and YWHAG expression in NSCLC specimens was demonstrated. Taken together, our present study revealed the tumor suppressive role of miR-509-5p in NSCLC by targeting YWHAG, suggesting that miR-509-5p/YWHAG axis might be considered as a novel and potential target for clinical diagnosis and therapeutics of NSCLC. (C) 2016 Elsevier Inc. All rights reserved.