Background: MiR-139-5p plays a significant role in tumorigenesis, metastasis and recurrence, suggesting that it may potentially be used as a promising biomarker for esophageal cancer diagnosis, prognosis and therapy. This study aimed to investigate the role and the mechanism of miRNA-139-5p in esophageal cancer. Methods: This study included 11 patients from an area with a high incidence of esophageal cancer. The expression levels of miRNA-139-5p in esophageal cancer tissues and para-carcinoma tissues of 11 patients were measured. We examined the expression of miR-139-5p in serum obtained from 92 consecutive patients from Cixian, which is a region in Hebei Province with a high rate of histologically confirmed esophageal cancer. The expression of miR-139-5p in esophageal cancer cell lines was detected. In the KYSE150 cell line with the lowest expression level of miR-139-5p, we transfected a plasmid to upregulate the expression level and examined the role of miR-139-5p in esophageal squamous cell carcinoma proliferation, migration and invasion. We conducted a gene profiling study using miR-139-5p cell lines to detect the expression of significant genes related to tumor progression, including cyclinD1, E-cadherin and VEGFR-1. We then constructed luciferase reporters containing miR-139-5p, which contained wild-type (WT) or mutated-type (Mut) VEGFR-1 binding sites to investigate the target. Results: MiRNA-139-5p expression levels in esophageal cancer tissues from 11 patients were significantly higher than those in para-carcinoma tissues. MiR-139-5p expression in the serum of 92 patients with esophageal cancer was associated with gender (P = 0.039) and TNM stage (P = 0.015). Factors that were not correlated with miR-139-5p expression were age (P = 0.293), smoking history (P = 0.397), length of tumor (P = 0.309), width of tumor (P = 0.296), depth of tumor (P = 0.724), lymphoma metastasis (P = 0.531) and postoperative therapy (P = 0.884). MiR-139-5p (P = 0.013) correlated significantly with observed survival rates. The lymphoma metastasis (P = 0.005) and TNM stage (P = 0.000) were significantly associated with observed survival rates. However, no significant relationships were found between the miR-139-5p and patient characteristics including gender, age, smoking history, tumor size and postoperative therapy. In the KYSE150 cell line, the expression level of miR-139-5p was the lowest. We transfected a plasmid to upregulate the expression level and found that the cell proliferation, metastasis and invasion abilities decreased. Upregulation of miR-139-5p inhibited the expression of Cyclin D1 and VEGFR-1 and increased the expression of E-cadherin. For further confirmation, we constructed luciferase reporters containing miR-139-5p, which contained wild-type (WT) or mutated-type (Mut) VEGFR-1 binding sites for target investigation. The results show that the corresponding VEGFR-1-Mut construct no longer suppressed miR-139-5p. Conclusions: MiR-139-5p may be a novel therapeutic target and prognostic biomarker of esophageal cancer. (C) 2018 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.