Clinicopathological and prognostic significance of microRNA-107 in human non small cell lung cancer

Background: MicroRNAs (miRNAs) are small, non-coding RNAs which can function as oncogenes or tumor suppressor genes in human cancers. Researchers have found that the expression level of miR-107 was decreased in human non-small cell lung cancer (NSCLC) tissues and cell lines, however, its clinicopathological and prognostic significance in NSCLC has not been investigated. Methods: Quantitative real-time PCR (qRT-PCR) was used to analyze the expression of miR-107 in 137 pairs of fresh NSCLC and matched adjacent normal tissue specimens. The chi-square test and Fishers exact tests were used to examine the associations between miR-107 expression and the clinicopathological characters. The overall survival (OS) and progression-free survival (PFS) were analyzed by log-rank test, and survival curves were plotted according to Kaplan-Meier. Results: The expression level of miR-107 was significantly lower in tumor tissues than that in corresponding noncancerous tissues (0.4676±0.2078 vs. 1.000±0.3953, P<0.001). Low expression of miR-107 was found to significantly correlate with TNM stage (p=0.001), regional lymph node involvement (p=0.04), and tumor differentiation (p=0.003). Kaplan-Meier analysis with the log-rank test indicated that low miR-107 expression had a significant impact on OS (35.2% vs. 69.3%; P=0.008) and PFS (30.0% vs. 56.2%; P=0.029). In a multivariate Cox model, we found that miR-107 expression was an independent poor prognostic factor for both 5-year OS (HR=2.57, 95% CI: 1.88-10.28; P=0.007) and 5-year PFS (HR=3.08, 95% CI: 2.01-8.92; P=0.003). Conclusion: The expression of miR-107 was decreased in NSCLC. Low expression of miR-107 was significantly associated with tumor progression and decreased survival in patients with NSCLC, indicating that miR-107 may serve as a novel prognostic marker in NSCLC.