Abstract
MicroRNAs play an important role in the migration and invasion of tumors, and lower expression of microRNA-1 (miR-1) has been proven in a variety of malignant tumors, including esophageal squamous cell carcinoma (ESCC). In this study, we found that miR-1 expression levels in tumor tissues and preoperative serum from esophageal carcinoma patients were lower than those in non-tumorous tissues and healthy volunteers. miR-1 expression in tissues and plasma was closely related to invasion, lymph node metastasis and TNM staging. Additionally, miR-1 expression levels in tissues and plasma were positively correlated. miR-1 inhibited cell proliferation, migration and invasion. Overexpression of miR-1 in ESCC cells reduced Notch2 protein but not mRNA levels, whereas suppression of miR-1 led to an increase in Notch2 protein but not mRNA levels. A dual-luciferase experiment validated that Notch2 was a direct target of miR-1. Introducing Notch2 mRNA into cells over-expressing miR-1 partially abrogated the effects of miR-1 on migration and invasion. Further studies verified that miR-1 regulates EMT signalling pathways directly through Notch2. Therefore, these results confirm that, as a tumor suppressor gene, miR-1 may be a potential tumor marker for the early diagnosis of ESCC and a new drug target.