Decreased expression of miR-133a correlates with poor prognosis in colorectal cancer patients

AIM: To investigate microRNA-133a (miR-133a) expression in colorectal cancer (CRC) and its relationship with tumorigenesis and disease prognosis. METHODS: Quantitative real-time polymerase chain reaction was used to measure levels of miR-133a in tumor samples and adjacent non-cancerous tissues from 169 patients undergoing radical resection for CRC. The associations between miR-133a expression and patient age, sex, as well as clinicopathologic parameters, such as tumor size, differentiation, location, invasion depth, metastasis, tumor-node-metastasis (TNM) stage and overall patient survival, were analyzed by Mann-Whitney U and Kruskal-Wallis tests. The Kaplan-Meier method and Cox proportional hazards regression analyses were performed to estimate the prognostic factors for patient survival prediction. RESULTS: The expression of miR-133a was significantly downregulated in CRC tissues compared with adjacent non-cancerous tissues (P < 0.05). This reduction was associated with the depth of the local invasion, poor differentiation, lymph node metastasis and advanced disease (P < 0.05). Moreover, Kaplan-Meier analysis demonstrated that patients with low miR-133a expression had poorer overall survival (OS) than those with high miR-133a expression (P < 0.001). Univariate analysis revealed statistically significant correlations between OS and miR-133a level, tumor local invasion, lymph node metastasis and TNM stage (P < 0.001). Furthermore, miR-133a levels and TNM stage were independently associated with OS (HR = 0.590, 95% CI: 0.350-0.995, P < 0.05; and HR = 6.111, 95% CI: 1.029-36.278, P < 0.05, respectively). CONCLUSION: The downregulation of miR-133a may play an important role in the progression of CRC and can be used as an independent factor to determine CRC prognosis. (C) 2014 Baishideng Publishing Group Inc. All rights reserved.