MiR-124 Inhibits Growth and Enhances Radiation-Induced Apoptosis in Non-Small Cell Lung Cancer by Inhibiting STAT3.

BACKGROUND/AIMS A growing body of evidence indicates that the abnormal expression of microRNAs (miRNAs) play an important role in sensitizing the cellular response to ionizing radiation (IR). The aim of this study was to investigate whether the expression of miR-124 correlated with radiosensitivity in the context of non-small-cell lung carcinoma (NSCLC). METHODS Quantitative reverse transcription polymerase chain reaction (RT-PCR) was used to quantify miR-124 expression in NSCLC tissues and cell lines. The role of miR-124 in NSCLC proliferation and radiosensitivity was analyzed using CCK-8 and flow cytometry apoptosis assays. Luciferase activity assays, RT-PCR, and Western blot assays were performed to confirm the target gene of miR-124. RESULTS In this study, we found that miR-124 was downregulated both in clinical NSCLC samples and in cell lines. miR-124 inhibited the proliferation of NSCLC cells and enhanced the apoptosis of NSCLC cells exposed to ionizing radiation. We identified signal transducer and activator of transcription 3 (STAT3) as a direct target of miR-124 by using target prediction algorithms and luciferase assays. Overexpression of STAT3 in A549 cell lines restored the enhanced radiosensitivity induced by miR-124. CONCLUSION Taking these observations into consideration, we illustrated that miR-124 is a potential target for enhancing the radiosensitivity of NSCLC cells by targeting STAT3.