MiR‐671‐5p sponging activity of circMMP1 promotes esophageal squamous cancer progression

BACKGROUND: The aim of this study was to explore the function and mechanism of circular RNA (circRNA) matrix metallopeptidase 1 (circMMP1) in the progression of esophageal squamous cell carcinoma (ESCC). METHODS: CircMMP1 expression was detected by quantitative real‐time PCR (qRT‐PCR), and its relationship with the prognosis of ESCC patients was evaluated by Kaplan–Meier analysis. Cells were transfected using corresponding plasmids, and the cell proliferation activity, migration and invasion capabilities in vitro were assessed. The protein level in tissues and cells was analyzed using western blotting. RNA pulldown, dual‐luciferase reporter assay and RNA immunoprecipitation assay were performed in ESCC cells to detect the interaction between circMMP1 and miR‐671‐5p, or the correlation between miR‐671‐5p and ANO1. Xenograft tumor experiment was carried out to uncover the function of circMMP1 in vivo. RESULTS: The high level of circMMP1 in tumor tissues was associated with poor prognoses of ESCC patients. Knockdown of circMMP1 suppressed ESCC cell proliferation, migration and invasion in vitro. MiR‐671‐5p was the target of circMMP1 and mediated the inhibition effect of circMMP1 on ESCC cells. CircMMP1 targeted miR‐671‐5p to regulate ANO1 expression, which was downstream of miR‐671‐5p. Overexpression of ANO1 weakened tumor‐repressive function of circMMP1 knockdown in ESCC cells. Moreover, silencing of circMMP1 impeded ESCC tumor growth in vivo. CONCLUSION: Our study provided novel evidence that circMMP1 accelerated ESCC progression by acting as a miR‐671‐5p sponge to enhance ANO1 expression.