Expression of miR-32 in human non-small cell lung cancer and its correlation with tumor progression and patient survival

Introduction: miR-32 has recently been found to be implicated in many critical processes in various types of human cancer. However, its clinical significance in human non-small cell lung cancer (NSCLC) has not yet been elucidated. In the present study, we investigated the expression of miR-32 in NSCLC and analyzed its association with clinical features and prognosis of NSCLC patients. Methods: Quantitative real-time PCR (qRT-PCR) was used to measure expression level of miR-32 in lung cancer cell lines, normal bronchial epithelial cells, 90 pairs of tumor samples and adjacent non-tumor tissues. To determine its prognostic value, overall survival was evaluated using the Kaplan-Meier method. Univariate and multivariate analysis were performed using the Cox proportional hazard analysis. Results: The expression of miR-32 was significantly decreased in lung cancer cell lines and NSCLC tissues compared with normal bronchial epithelial cells and adjacent non-tumor tissues (P < 0.05). This reduction of miR-32 was associated with tumor stage and lymph node metastasis (P < 0.05). Moreover, Kaplan-Meier analysis demonstrated that patients with low miR-32 expression had shorter overall survival time than those with high miR-32 expression (P < 0.05). Univariate analysis revealed statistically significant correlations between overall survival and miR-32 level, tumor stage and lymph node metastasis (P < 0.05). Furthermore, miR-32 levels, tumor stage and lymph node metastasis were independently associated with overall survival (P < 0.05). Conclusions: Our results provided the first evidence that down-regulation of miR-32 was correlated with NSCLC progression, and miR-32 might be a potential molecular biomarker for predicting the prognosis of patients.