Effect of flavonoids hydroxygenkwanin on vascular smooth muscle cell proliferation, migration, and neointimal formation

Background Restenosis and atherosclerosis are chronic inflammatory disease. Abnormal vascular smooth muscle cell (VSMC) proliferation and migration play crucial roles in neointimal hyperplasia and restenosis progression in response to stimulation with various inflammatory cytokines, such as platelet-derived growth factor-BB (PDGF-BB) and tumour necrosis factor-α (TNF-α). Hydroxygenkwanin (HGK) exerts remarkable anti-inflammatory, antitumour, antiproliferative and antimigratory effects. The aim of the study was to evaluate and elucidate the therapeutic effect and regulatory mechanism of HGK on neointimal hyperplasia. Methods To determine the therapeutic effects of HGK in PDGF-BB- or TNF-α-treated VSMCs, MTT assays, Western blotting analysis, cell cycle analysis, BrdU incorporation assay, wound healing assay and adhesion assay were performed in vitro. A docking assay was also used to elucidate the mechanism underlying the regulatory effect of HGK. Histological and immunohistochemical staining of denuded femoral arteries was conducted to elucidate the therapeutic effect of HGK in an in vivo assay. Results HGK inhibited the abnormal proliferation, migration, and inflammation of PDGF-BB- or TNF-α-treated VSMCs through regulation of the PDK1/AKT/mTOR pathway. In addition, HGK promoted circulating endothelial progenitor cell (EPC) chemotaxis. In an in vivo assay, HGK dramatically enhanced re-endothelization and reduced neointimal hyperplasia after femoral artery denudation with a guide wire in mice. Conclusions In the present study, HGK decreased the PDGF-BB- or TNF-α-induced abnormal proliferation, migration and inflammation in VSMCs and improved re-endothelialization and neointimal hyperplasia in denuded femoral arteries. These results provide a novel potential treatment for restenosis in the future. ![Figure][1] HGK decreases VSMC abnormal proliferation, migration and inflammation through PDK1/AKT/mTOR/S6K inhibition and promotes EPC chemotaxis and reendothelialization. HGK is a potential therapeutic candidate for intimal hyperplasia and restenosis. ### Competing Interest Statement The authors have declared no competing interest. * VSMC : vascular smooth muscle cell TNF-α : tumor necrosis factor-α PDGF-BB : platelet-derived growth factor-BB HGK : hydroxygenkwanin EPCs : endothelial progenitor cells VCAM-1 : vascular cell adhesion protein 1 ICAM-1 : intercellular adhesion protein 1 ATP7A : copper-transporting ATPase Rac1 : Rac family small GTPase 1 PDK1 : phosphoinositide-dependent protein kinase 1 ED : endothelial denudation PAI-1 : plasminogen activator inhibitor 1 TF : tissue factor PTEN : phosphatase and tensin homolog mTOR : mammalian target of rapamycin S6K : S6 kinase PCNA : proliferating cell nuclear antigen ROS : reactive oxygen species [1]: pending:yes