Abstract
Lung cancer is the most common cancer worldwide, and morbidity and mortality associated with lung cancer has been increasing annually in recent decades. MicroRNAs (miRNAs), which are short non‑coding RNA sequences that are involved in the regulation of gene expression, have been previously demonstrated to be key regulators in cancer. The present study aimed to clarify the role of miRNA (miR)‑1284 in lung cancer. A549 lung carcinoma cells were transfected with miR‑1284 mimic or miR‑1284 inhibitor using Lipofectamine 2000. Subsequently, cell viability, growth and apoptosis of A459 cells in the miR‑1284 mimic, miR‑1284 inhibitor and control groups were assayed by MTT assay, bromodeoxyuridine assay and flow cytometry, respectively. Furthermore, the protein expression levels of p27, p21, Bax, pro‑caspase‑3, activated caspase‑3 and Myc were detected by western blot analysis to investigate the molecular mechanisms underlying the effect of miR‑1284 on A549 cells. The cell viability and growth of A549 cells were significantly decreased in the miR‑1284 mimic group compared with the control group, whereas the percentage of apoptotic cells was significantly increased. By contrast, miR‑1284 inhibitor transfection significantly increased the cell viability and growth compared with control, and decreased apoptosis. Furthermore, expression of p27 was increased in miR‑1284 mimic‑transfected A549 cells compared with the control group, whereas p21 was unaffected by miR‑1284 overexpression or inhibition. The expression of Myc was decreased by miR‑1284 mimic transfection compared with the control group. For the other apoptosis‑associated proteins that were investigated (Bax, pro‑caspase‑3 and active caspase‑3), the expression levels in the miR‑1284 mimic transfected cells were higher than in the other two groups (control and miR‑1284 inhibitor). In conclusion, the results suggest that miR‑1284 affects cell proliferation and apoptosis of lung cancer cells, indicating that miR‑1284 may have a key role in lung tumorigenesis.