Decreased microRNA-224 and its clinical significance in non-small cell lung cancer patients

BACKGROUND: MicroRNA-224 has been proven dysregulated in some human malignancies and correlated with tumor progression. However, its expression and clinical significance in non–small cell lung cancer (NSCLC) is still unclear. Thus, the aim of this study was to explore the effects of miR-224 in NSCLC tumorigenesis and development. METHODS: Using real-time quantitative RT-PCR, we detected miR-224 expression in NSCLC cell lines and primary tumor tissues. The association of miR-224 expression with clinicopathological factors and prognosis was also statistically analyzed. MTT, flow cytometric, Transwell invasion and migration assays, and scratch migration assay were used to test the proliferation, apoptosis, invasion, and migration of NSCLC cells after miR-224 mimics transfection. RESULTS: MiR-224 expression levels were significantly down-regulated in NSCLC compared to the corresponding noncancerous lung tissues (P <0.001). In addition, decreased miR-224 expression was significantly associated with lymph node metastasis (P = 0.002), advanced TNM stage (P <0.001), and shorter overall survival (P <0.001). Multivariate regression analysis corroborated that down-regulation of miR-224 was an independent unfavourable prognostic factor for patients with NSCLC. Furthermore, transfection of miR-224 mimics in NSCLC A549 cells was able to reduce cell proliferation, invasion, and migration, and promote cell apoptosis. CONCLUSIONS: These findings indicate that miR-224 may act not only as a novel diagnostic and prognostic marker, but also as a potential target for miR-based therapy of NSCLC. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_198