MicroRNA-105 promotes epithelial-mesenchymal transition of nonsmall lung cancer cells through upregulating Mcl-1.

BACKGROUND: A growing number of microRNAs have been proved to play significant roles in limiting tumor growth and the epithelial-mesenchymal transition (EMT) process of nonsmall cell lung cancer (NSCLC). Present work aims to study the function of microRNA (miR)-105 in EMT of NSCLC cells, which is unrevealed yet. METHODS: Two NSCLC cell lines A549 and Calu-3 were transfected with miR-105 mimic, inhibitor, or scrambled control. And then the effects of miR-105 were evaluated by performing trypan blue staining, transwell assay, ANNEXIN-FITC/propidium iodide (PI) double staining and Western blot analysis. The expression levels of myeloid cell leukemia-1 (Mcl-1) after transfection were tested by real-time quantitative polymerase chain reaction and Western blot analysis. Whether Mcl-1 was a downstream effector of miR-105, and the involvement of mammalian target of Rapamycin (mTOR) and p38 mitogen-activated protein kinase (p38MAPK) signaling pathways were assessed. RESULTS: The overexpression of miR-105 significantly increased the viability and migration of A549 and Calu-3, but had no impacts on cell apoptosis. Meanwhile, E-cadherin was remarkably downregulated, and N-cadherin, Vimentin, ZEB1, and Snail were upregulated by miR-105 overexpression. Mcl-1 was positively regulated by miR-105, and the effects of miR-105 overexpression on A549 and Calu-3 cells viability, migration and EMT were all flattened by Mcl-1 silence. Both mTOR and p38MAPK pathways were activated in miR-105-overexpressing and Mcl-1-overexpressing cells. Besides, inhibition of mTOR and p38MAPK pathways by using Rapamycin and VX-702 abolished the regulatory effects of Mcl-1 on EMT. CONCLUSION: Our study underlines the importance of miR-105 in modulating NSCLC cells EMT. miR-105 promoted the EMT of NSCLC cells possibly via upregulation of Mcl-1 and thereby activation of mTOR and p38MAPK signaling.