Prognostic Significance of Serum miRNA-21 Expression in Human Non-Small Cell Lung Cancer

Background: Deregulation of microRNAs (miRNAs) plays important roles in tumor progression. The aim of this study was to investigate miR-21 expression in serum of non-small cell lung cancer (NSCLC) and its correlation with prognosis of NSCLC patients. Methods: Dysregulated miRNAs in NSCLC serum were identified by microarray. MiR-21 expression in NSCLC and control serum was detected by TaqMan RT-PCR assay. The correlation of serum miR-21 with clinicopathological factors of NSCLC patients was analyzed. Furthermore, the prognostic significance of serum miR-21 was analyzed by using Kaplan-Meier curves with log-rank tests and a Cox proportional hazard model. Results: The level of miR-21 expression was higher in NSCLC serum samples than in control serum samples (P < 0.01). High serum miR-21 was significantly correlated with tumor-node metastases stage and lymph node metastasis of NSCLC patients (P = 0.016 and 0.026, respectively). The 3-year actuarial overall survival rates in NSCLC patients with high serum miR-21 expression (39.8%) was significantly shorter than those with low serum miR-21 expression (58.2%; P < 0.001). Furthermore, univariate and multivariate analyses for overall survival showed that serum miR-21 expression was an independent prognostic factor for NSCLC patients (P = 0.015, RR = 2.01, 95% CI: 1.78-3.26). Conclusion: Serum miR-21 expression might be useful as a prognostic marker for NSCLC patients. J. Surg. Oncol. 2011;104:847-851. (C) 2011 Wiley Periodicals, Inc.