The decreased expression of miR-625 predicts poor prognosis of esophageal squamous cell carcinoma.

BACKGROUND: Previous study has detected the expression of miR-625 in esophageal squamous cell carcinoma (ESCC) and found that miR-625 was related to tumor depth, stage, and metastasis of ESCC. However, the prognostic value of miR-625 in ESCC has not yet been reported. METHODS: Real-time quantitative PCR was employed to measure the expression level of miR-625 in clinical ESCC tissues. Survival curves were made using the Kaplan-Meier method, and the log rank test was used to analyze the differences between clinicopathological characteristics and survival in ESCC patients. RESULTS: The expression level of miR-625 in ESCC tissues was significantly lower than that in adjacent non-tumor tissues (1.00 ± 0.38 vs. 3.25 ± 1.83, P < 0.0001). Low miR-625 expression was observed to be closely correlated with lymph node metastasis (P = 0.01), distant metastasis (P = 0.007), tumor differentiation (P = 0.04), and advanced TNM stage (P = 0.005). The 5-year overall survival rate in the low expression group was 38.1%, compared with 68.8% in the high expression group (log-rank test, P = 0.001). Multivariate Cox regression analysis showed that miR-625 expression level (HR = 3.72, 95% CI: 1.36-8.78, P = 0.005) was an independent factor in predicting the overall survival of ESCC patients. CONCLUSION: Our findings provide the convincing evidence for the first time that the down-regulation of miR-625 may serve as a novel molecular marker to predict the aggressive tumor progression and unfavorable prognosis of ESCC patients.