MicroRNA‐7‐5p induces cell growth inhibition, cell cycle arrest and apoptosis by targeting PAK2 in non‐small cell lung cancer

MicroRNAs (miR) are known to be critical regulators in tumor progression. miR‐7‐5p was reported to be involved in several cancers, including glioblastoma, cervical cancer, and melanoma, but its prognostic value and biological function in non‐small‐cell lung cancer (NSCLC) remain unclear. In this study, using quantitative real‐time PCR analysis, we found that miR‐7‐5p was significantly downregulated in NSCLC tissues and cell lines. Lower miR‐7‐5p expression was associated with tumor–node–metastasis stage and tumor size by chi‐squared test. Deceased miR‐7‐5p expression was associated with a worse prognosis in patients with NSCLC using Kaplan–Meier survival analysis and multivariate Cox regression analysis. Experiments in NSCLC cell lines (A549 and H1299) demonstrated that upregulation of miR‐7‐5p significantly suppressed cell proliferation, but induced cell cycle G0/G1 phase arrest and apoptosis using Cell Counting Kit‐8, colony formation, and flow cytometry analysis. Through loss‐of‐function assays, we further demonstrated that downregulation of miR‐7‐5p promoted cell proliferation and cell cycle G1/S transition, but decreased cell apoptosis in SPC‐A1 cells. Furthermore, P21‐activated kinase 2 (PAK2) was predicted and confirmed as a direct target gene of miR‐7‐5p in NSCLC cells by luciferase reporter assay. In addition, we found PAK2 overexpression could partially reverse the effects of miR‐7‐5p on cell proliferation, cell cycle distribution, and apoptosis. We thus concluded that lower expression of miR‐7‐5p was associated with poor prognosis and NSCLC progression by directly targeting PAK2.