MiR-519d reduces the 5-fluorouracil resistance in colorectal cancer cells by down-regulating the expression of CCND1

OBJECTIVE: To Investigate the effects of miR-519d on the 5-fluorouracil resistance in colorectal cancer cells and to explore the mechanism. MATERIALS AND METHODS: Colorectal cancer cells HCT116 and SW480 were transfected with miR519d-mimic or siCCND1 by transient transfection. The sensitivity of cells to 5-Fu was assayed by MTT assay. Dual luciferase assay was used to examine the effect of CCND1 on the sensitivity of cells to 5-Fu mediated by miR-519d, RESULTS: MiR-519d was overexpressed in colorectal cancer cells after transient transfection with miR-519d mimics. Overexpression of miR-519d increased the sensitivity of colorectal cancer cells to 5-Fu. MiR-519d negatively regulated the expression of CCND1 via directly bound to CCND1 3'UTR. si-CCND1 could down regulate the CCND1 expression in colorectal cancer HCT116 and SW480 cells. si-CCND1 increased the sensitivity of colorectal cancer cells to 5-Fu. CONCLUSIONS: miR-519d inhibits the expression of CCND1 and then plays a role in alleviating 5-Fu resistance in colorectal cancer cells.