Effect of miR-18a overexpression on the radiosensitivity of non-small cell lung cancer

The aim of the present study is to investigate whether there is a relationship between miR-18a expression and radiosensitization of non-small-cell lung caner (NSCLC). The relationship between miR-18a expression and clinicopathological characteristics was investigated. To determine whether the miR-18a expression levels were associated with radiotherapeutic efficacy, therapeutic response was evaluated by radiologic Response Evaluation Criteria in Solid Tumors (RECIST). To determine whether miR-18a was required for lung cancer cell radioresistance, A549 cells were treated with different doses of ionizing radiation, following transfection with inhibitor miR-18a or inhibitor NC. We found that the level of miR-18a in NSCLC was strongly correlated with tumor differentiation (P = 0.026), regional lymph node metastasis (P = 0.013) and clinical TNM stage (P = 0.005). According to RECIST, miR-18a expression level was significantly associated with therapeutic response, exhibiting higher expression level in non-responsive patients. Furthermore, the depletion of miR-18a increased A549 cell radiosensitivity. In conclusion, we provide the evidence that down-regulation of miR-18a sensitizes NSCLC to radiation treatment, and it may help to develop a new approach to sensitizing radioresistant lung cancer cells by targeting miR-18a.