MicroRNA-137 Inhibits Esophageal Squamous Cell Carcinoma by Downregulating DAAM1

Background: A growing body of evidence demonstrates that miR-137 acts against cancers; however, the biological function of miR-137 in esophageal squamous cell carcinoma (ESCC) remains to be fully understood. Objective: The aim of this study is to explore the role of miR-137 in ESCC. Methods: miR-137 expression was detected by reverse-transcription quantitative polymerase chain reaction (RT-qPCR), and target protein expression was detected by western blot. Cell counting, colony formation and flow cytometry were employed to determine the effects of miR-137 on the growth of ESCC cells. Dual-luciferase reporter assay was performed to validate the binding of miR- 137 with a dishevelled-associated activator of morphogenesis 1 (DAAM1) 3’-UTR. Results: miR-137 was shown to be down-regulated in ESCC. miR-137 expression was inversely correlated with the 5-year survival rate of ESCC patients. Up-regulated miR-137 attenuated ESCC proliferation and promoted ESCC cell apoptosis. Meanwhile, to further reveal how miR-137 regulated the malignant behaviors of ESCC, the downstream mRNA binding targets of miR-137 were explored. miR-137 was demonstrated to bind DAAM1 3’-UTR and repressed the expression of DAAM1. The expression of DAAM1 and miR-137 in ESCC was inversely correlated. Additionally, the reintroduction of DAAM1 had the capacity to reverse the negative role of miR- 137 in ESCC cell growth. Conclusion: These findings have uncovered the new function of miR-137 in ESCC via negatively regulating DAAM1, suggesting miR-137 as a potent therapeutic candidate for ESCC treatment.