Overexpression of microRNA-611 inhibits TGF-β-induced epithelial-mesenchymal transition and migration in lung cancer cells through MAPKAP1.

Metastasis is a major cause of death in patients with lung cancer (LC). microRNA-611 (miR-611), a miRNA, has been little studied in cancer. Here, we aimed to further elucidate the roles of miR-611 in epithelial-mesenchymal transition (EMT) and migration induced by transforming growth factor-β (TGF-β) in LC cells and the possible underlying mechanisms. miR-611 and MAPKAP1 expression was first identified in LC tissues from metastatic and nonmetastatic patients, and their expression was associated with overall survival. Gain- and loss-of-function experiments were performed to verify the impacts of miR-611 and MAPKAP1 on pAKT expression, EMT, and migration in LC cells treated with TGF-β. The interaction between miR-611 and MAPKAP1 was also determined with a luciferase reporter assay. In our study, miR-611 was expressed at low levels, and MAPKAP1 was highly expressed in LC tissues, which was associated with metastasis and short overall survival. Functionally, miR-611 inhibition or MAPKAP1 overexpression accelerated EMT and migration and upregulated pAKT in TGF-β-treated A549 and H1299 cells; miR-611 overexpression or MAPKAP1 silencing exerted the opposite effects as miR-611 inhibition or MAPKAP1 overexpression. Mechanistically, miR-611 could target and downregulate MAPKAP1. MAPKAP1 expression was also negatively correlated with miR-611 expression in LC tissues. In addition, miR-611 overexpression reduced the EMT and migration of TGF-β-treated A549 and H1299 cells by targeting MAPKAP1. In conclusion, miR-611 overexpression attenuated EMT and migration by targeting MAPKAP1 in TGF-β-induced LC cells, indicating that miR-611 is a biological target for LC treatment.