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-133 a in tumor samples and adjacent non-cancerous tissues from 169 patients undergoing radical resection for CRC. The associations between miR-133 a 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 MannWhitney 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-133 a 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-133 a expression had poorer overall survival(OS) than those with high miR-133 a expression(P < 0.001). Univariate analysis revealed statistically significant correlations between OS and miR-133 a level, tumor local invasion, lymph node metastasis and TNM stage(P < 0.001). Furthermore, miR-133 a 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-133 a may play an important role in the progression of CRC and can be used as an independent factor to determine CRC prognosis.

miR-422a is an independent prognostic factor and functions as a potential tumor suppressor in colorectal cancer

AIM: To determine the expression of mi R-422 a in colorectal cancer(CRC) tissues and to further explore the prognostic value and function of mi R-422 a in CRC carcinogenesis.METHODS: mi R-422 a expression was analyzed in 102 CRC tissues and paired normal mucosa adjacent to carcinoma by quantitative real-time PCR. The relationship of mi R-422 a expression with clinicopathological parameters was also analyzed. Kaplan-Meier analysis and Cox multivariate analysis were performed to estimate the potential role of mi R-422 a. Cell proliferation, migration, and invasion were used for in vitro functional analysis of mi R-422 a.RESULTS: The levels of mi R-422 a were dramatically reduced in CRC tissues compared with normal mucosa(P < 0.05), and significantly correlated with local invasion(P = 0.004) and lymph node metastasis(P < 0.001). Kaplan-Meier survival and Cox regression multivariate analyses revealed that mi R-422 a expression(HR = 0.568, P = 0.015) and clinical TNM stage(HR = 2.942, P = 0.003) were independent prognostic factorsfor overall survival in CRC patients. Furthermore, in vitro experiments showed that overexpression of mi R-422 a inhibited the proliferation, migration, and invasion of SW480 and HT-29 cells.CONCLUSION: Down-regulation of mi R-422 a may serve as an independent prognosis factor in CRC. Mi R-422 a functions as a tumor suppressor and regulates progression of CRC.