Objective:To investigate the effect and mechanism of miRNA-24 on the proliferation,migration and tube forma tion of vascular endothelial cells.Methods:Human umbilical vein endothelial cells (HUVECs) were assigned into control,microRNA (miR) 24 overexpression and anti-miR-24 groups.The proliferation and migration abilities of HUVECs were detected by methyl thiazolyl tetrazolium (MTT) assay and scratch wound healing assay,respectively.The ability of HUVECs to form tubular structures was evaluated by a tube formation assay.The mRNA and protein expressions of vascular endothelial growth factor (VEGF) and transcription factor Sp1 were determined by RT-PCR,immunocytochemis try and western blotting,respectively.Results:The miR-24 overexpression group exhibited decreased cell proliferation and migration,and expressions of VEGF and Sp1 compared with the control group (P ＜ 0.01).No tube like network structure was formed in the miR-24 overexpression group.However,inhibition of miR 24 in HUVECs markedly in creased cell proliferation and migration,enhanced tube for mation and expressions of VEGF and Sp1 (P＜0.05 or P＜ 0.01).Conclusion:MiR-24 suppressed the proliferation,migration and tube formation of HUVECs,and the mechanism might be related to the down-regulation of VEGF expression.Sp1 might participate in this regulation process.