Background and purpose: It was reported that many microRNAs (miRNAs) have close relation with carcinomas. miR-31 (microRNA-31) shows abnormal change in numerous cancers. China is one of the most high-risk areas of esophageal squamous cell carcinoma (ESCC). The aim of the present study was to investigate the expression of miR-31 in ESCC

and analyze the relationship of its expression with clinicopathological features and prognosis. Methods: The expression of miR-31 in KYSE410

EC1 and EC9706 cell lines

as well as 81 cases of ESCC tissues and adjacent normal esophageal tissues were detected by real-time reverse transcription-polymerase chain reaction (RT-PCR). The result was combined with clinical and follow-up data and statistical analysis was conducted. Results: MiR-31 was up-expression in 3 cell lines and 75.31% of the ESCC tissues. miR-31 up-expression was positively related to severer lymph node metastasis (P=0.043)

deeper invasion of tumors (P=0.002) and advanced pathological stage (P=0.027). There was no relationship of miR-31 with other clinicopathological features (P0.05). Furthermore

high expression of miR-31 was associated with poor progression-free survival (PFS) in 81 ESCC patients by Kaplan-Meier analysis (P=0.014) and by multivariate Cox analysis (P=0.021). Conclusion: Our results identified miR-31 may be a new diagnostic criteria and prognostic biomarker for ESCC.