MicroRNA-21 regulates non-small cell lung cancer cell proliferation by affecting cell apoptosis via COX-19

Aims: This study is to investigate the regulatory effect of microRNA-21 (miR-21) on bone metastasis of non-small cell lung cancer (NSCLC). Methods: In this study, 18 patients were diagnosed with vertebral column metastasis of NSCLC. MiR-21 or small interfering RNAs were transfected into H2170 cells using Lipofectamine 2000. Real-time PCR was performed to detect miR-21 expression. Western blotting was used to measure the expression of COX-19 protein. Enzymatic activity tests were performed to measure the activity of cytochrome C oxidase. Flow cytometry was used to monitor changes in cell apoptotic rate. MTT assay was used to determine the capability of cell proliferation. Results: Bone metastasis of NSCLC enhanced the levels of miR-21 in NSCLC patients. Proliferation capability of cells with high expression of miR-21 was greater than that of cells with the inhibition of miR-21 expression. High expression of miR-21 promoted cell proliferation by inhibiting cell apoptosis. COX-19 was a key factor in the inhibition of apoptosis by miR-21. Inhibition of COX-19 expression reduced cell proliferation by enhancing cell apoptosis. Conclusions: This study demonstrates that inhibition of miRNA-21 suppresses NSCLC cell proliferation by promoting cell apoptosis via the decrease of COX-19 expression.