Over expression of miR-200c suppresses invasion and restores methotrexate sensitivity in lung cancer A549 cells.

MicroRNAs have become recognized as key players in the development of malignancy. MiR-200c can function as a tumor suppressor gene. However, the effect of miR-200c on methotrexate resistance remains unclear to date. This study aims to evaluate the function of miR-200c in lung cancer A549 cells. The data presented in our study demonstrated that the expression of miR-200c was down-regulated in methotrexate-resistant A549 cells. Over expression of miR-200c could significantly inhibit cell proliferation, induce G0/G1 cell cycle arrest and induce cell apoptosis. RT-PCR and Western blot assays showed that the expression of P53 and P21 were significantly increased with miR-200c overexpression. These results indicated that over expression of miR-200c might enhance the sensitivity of A549 cells to methotrexate through the P53/P21 pathway. Furthermore, miR-200c overexpression significantly inhibited cell migration and invasion with increasing the expression of E-cad and decreasing the expression of EZH2. In consequence, we provide a mechanism of acquired resistance to methotrexate that is caused by the loss of miR-200c in lung cancer cells. Along with this, our study demonstrates the complex network of microRNA mediated chemoresistance.