MiR-106b exhibits an anti-angiogenic function by inhibiting STAT3 expression in endothelial cells

Recent discoveries of the atherosclerosis-related miRNAs shed new light on the treatment of cardiovascular diseases. Of note, miR-106b ~ 25 cluster and miR-17 ~ 92 cluster are paralogs. Up till now, plenty of researches have shown the role of miR-17 ~ 92 cluster in tumor and atherosclerosis, but miR-106b ~ 25 cluster has stayed mysterious in atherosclerosis field. This study was designed to investigate how miR-106b functions in the atherosclerosis-related angiogenesis and to explore the functioning processes of miR-106b, so as to seek out a new target for the treatment of atherosclerosis.

Up and down regulation of miR-106b expression was achieved through transfection in HUVECs so as to investigate the function of miR-106b. Next we predicted the target genes of miR-106b and detected them using qRT-PCR and Western blot technique. At last, luciferase assay was conducted to verify the direct target gene of miR-106b. Data are expressed as mean ± SEM. Two treatment groups were compared by Mann-Whitney U test or student's t-test. Results were considered statistically significant when P < 0.05.

The results showed miR-106b up-regulation groups formed less tubes than control groups while the down-regulation groups showed the opposite. Meanwhile, no obvious effect on apoptosis was observed in endothelial cells. Next we predicted the target genes of miR-106b and finally settled down to MAPK14 (Mitogen-Activated Protein Kinase), STAT3 (Signal Transducers and Activators of Transcription 3), JAK1(Janus Kinase 1) and VEGFA(Vascular Endothelial Growth Factor A) as candidate target genes. Our results revealed over-expressed miR-106b represses STAT3 expression, while miR-106b inhibition resulted in STAT3 up-regulation. Ultimately, luciferase assay confirmed STAT3 mRNA is the direct target of miR-106b.

Our research demonstrated that miR-106b modulate angiogenesis in endothelial cells through affecting expression of STAT3, which occurs by direct target action. Therefore, we affirmed that miR-106b exerts an anti-angiogenic effect in endothelial cells via STAT3-involved signaling pathway, via directly targeting STAT3.