Down-regulation of microRNA-181b is a potential prognostic marker of non-small cell lung cancer.

The aim of this study was to investigate the clinical significance of microRNA-181b (miR-181b) expression in non-small cell lung cancer (NSCLC). MiR-181b expression in 126 pairs of surgically removed NSCLC tissues and their corresponding normal lung tissues was measured by real-time quantitative RT-PCR assay. Additionally, the correlation of miR-181b expression with clinicopathological factors or prognosis of patients was analyzed. At first, miR-181b expression was significantly down-regulated in NSCLC tissues as compared with their normal counterparts (P<0.001). Then, the low miR-181b expression was found to be closely correlated with larger tumor size (P=0.02), higher p-TNM stage (P=0.008) and positive lymph node metastasis (P=0.03) of NSCLC patients. After that, survival analysis found that the overall survival (P=0.001) and disease-free survival (P=0.008) of NSCLC patients with low miR-181b expression were both significantly poorer compared to those patients with high miR-181b expression. Finally, both univariate and multivariate analyses demonstrated that low miR-181b expression may be a poor prognostic marker of NSCLC patients. This is the first study to indicate that down-regulation of miR-181b may be correlated with aggressive disease progression and poor prognosis of NSCLC patients, suggesting that miR-181b might be involved in lung carcinogenesis and become a potential prognostic marker for NSCLC.