Downregulation of microRNA-449a-5p promotes esophageal squamous cell carcinoma cell proliferation via cyclin D1 regulation

Aberrant microRNA-449a (miR-449a-5p) expression has been demonstrated to be associated with the development of various cancer types. However, the effect of miR-449a-5p on esophageal squamous cell carcinoma (ESCC) cell proliferation remains unknown. The present study aimed to determine whether miR-449a-5p may regulate ESCC cell proliferation via negative regulation of cyclin D1. Reverse transcription quantitative-polymerase chain reaction was used to measure the expression of miR-449a-5p in ESCC tissues and cells. Western blot was performed to analyze the protein level of cyclin D1. The proliferation of ESCC cells was determined by MTT and clone formation assay. Paired ESCC and adjacent normal esophageal squamous tissues were collected from patients with ESCC. It was demonstrated that miR-449a-5p expression was reduced, whereas cyclin D1 expression was increased in ESCC tissues compared with adjacent normal tissues. Proliferation was investigated in vivo using the ESCC cell line Eca-190. miR-449a-5p inhibitor transfection facilitated the proliferation of Eca-109 cells. By contrast, transfection with miR-449a-5p mimics inhibited Eca-109 cell proliferation. Furthermore, it was confirmed that miR-449a-5p directly bound to the 3′-untranslated region of cyclin D1. Transfection with cyclin D1 small interfering RNA reversed the effects of the miR-449a-5p inhibitor on Eca-109 cell proliferation. In conclusion, miR-449a-5p may control ESCC proliferation through the negative regulation of cyclin D1 expression.