Cells plated in a 48-well plate were co-transfected with 50 nM miRNA mimics or negative control oligonucleotides, 50 ng of firefly luciferase reporter and 10 ng of pRL-TK using the jetPRIME.

BACKGROUND/AIMS: Increasing evidence indicates that microRNAs (miRNAs) play important roles in Kawasaki disease (KD). Our previous study demonstrated that hsa-miR-27b-3p (miR-27b) was up-regulated in KD serum. However, the specific role of miR-27b in KD remains unclear. We aimed to investigate that miR-27b could be a biomarker and therapeutic target for KD treatment. As well, the specific mechanism of miR-27b effecting endothelial cell functions was studied. METHODS: The expression of miR-27b and Smad7 was measured by qRT-PCR. Gain-of-function strategy was used to observe the effect of miR-27b on human umbilical vein endothelial cells (HUVECs) proliferation and migration. Bioinformatics analyses were applied to predict miR-27b targets and then we verified Smad7 by a luciferase reporter assay. Western blot was performed to detect the protein expression of Smad7, PCNA, MMP9, MMP12 and TGF-beta-related genes. RESULTS: We confirmed that miR-27b was shown to be dramatically up-regulated in KD serum and KD serum-treated HUVECs and that elevated expression of miR-27b suppressed the proliferation and migration of HUVECs. Furthermore, our results verified that miR-27b mediated cell functions by affecting the TGF-beta via targeting Smad7 in HUVECs. CONCLUSION: These results suggested that up-regulated miR-27b had a protective role in HUVECs proliferation and migration via targeting Smad7 and affecting TGF-beta pathway. Therefore, miR-27b represented a potential biomarker for KD and may serve as a promising therapeutic target for KD treatment.