Overexpression of miR-4443 promotes the resistance of non-small cell lung cancer cells to epirubicin by targeting INPP4A and regulating the activation of JAK2/STAT3 pathway.

We aimed to elucidate the roles and regulatory mechanism of miR-4443 in regulating the resistance of non-small cell lung cancer (NSCLC) cells to epirubicin (EPI). Fifty-four advanced NSCLC patients were classified as ''insensitive'' or ''sensitive'' according to patient's responses following EPI-based chemotherapy and then the expression of miR-4443 was determined. The EPI-resistant H1299 cells were collected and transfected with miR-4443 mimics, whereas parental H1299 cells were transfected with miR-4443 inhibitors. The inhibition of growth (IC50), cell cycle or apoptosis of different transfected groups were investigated. Additionally, the potential target of miR-3188 was identified and verified by luciferase reporter assay. Besides, the regulatory relationship between miR-3188 and JAK2/STAT3 pathway was explored. miR-4443 was highly expressed in insensitive NSCLC patients to EPT-based chemotherapy and EPI-resistant H1299 cells. Inhibition of miR-4443 increased the sensitivity of EPI-resistant H1299 cells to EPI by decreasing IC50 of EPI, inducing cell apoptosis and G0/G1 cell cycle arrest, while overexpression of miR-4443 promoted the resistance of parental H1299 cells to EPI. Furthermore, inositol polyphosphate 4-phosphatase type I gene (INPP4A) was a target of miR-4443 and its expression could be negatively regulated by miR-4443. Overexpression of miR-4443 promoted the resistance of parental H1299 cells to EPI by targeting INPP4A. Besides, overexpression of miR-4443 activated JAK2/STAT3 pathway in parental H1299 cells to EPI. Overexpression of miR-4443 may promote the resistance of NSCLC cells to EPI by targeting INPP4A and regulating the activation of JAK2/STAT3 pathway. miR-4443 may serve as a drug target for NSCLC.