α-Iso-Cubebene Inhibits PDGF-Induced Vascular Smooth Muscle Cell Proliferation by Suppressing Osteopontin Expression

• Published in: PloS one Vol. 12; no. 1; p. e0170699
• Main Authors: Jang, Min A, Lee, Seung Jin, Baek, Seung Eun, Park, So Youn, Choi, Young Whan, Kim, Chi Dae
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.01.2017; Public Library of Science (PLoS)
• Subjects: Activator protein 1; Animal tissues; Animals; Aorta; Atherosclerosis; Attenuation; Binding sites; Biocompatibility; Biology and Life Sciences; Cell cycle; Cell growth; Cell proliferation; Cell Proliferation - drug effects; Cells, Cultured; Circulatory system; Cubebene; Growth factors; Herbal medicine; Laboratory animals; Lignin; Medicine; Medicine and Health Sciences; Mice; Mice, Inbred C57BL; Monoclonal antibodies; Muscle, Smooth, Vascular - cytology; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - metabolism; Muscles; Osteopontin; Osteopontin - metabolism; Pharmacology; Platelet-derived growth factor; Platelet-Derived Growth Factor - antagonists & inhibitors; Platelet-Derived Growth Factor - pharmacology; Rats; Rats, Sprague-Dawley; Research and Analysis Methods; Rodents; Schisandra; Sesquiterpenes - pharmacology; Signaling; siRNA; Smooth muscle; Thorax; Transcription factors; Vascular diseases
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0170699

α-Iso-cubebene (ICB) is a dibenzocyclooctadiene lignin contained in Schisandra chinensis (SC), a well-known medicinal herb that ameliorates cardiovascular symptoms. Thus, we examined the effect of ICB on vascular smooth muscle cell (VSMC) proliferation, a key feature of diverse vascular diseases. When VSMCs primary cultured from rat thoracic aorta were stimulated with PDGF (1-10 ng/ml), cell proliferation and osteopontin (OPN) expression were concomitantly up-regulated, but these effects were attenuated when cells were treated with MPIIIB10, a neutralizing monoclonal antibody for OPN. In aortic tissues exposed to PDGF, sprouting VSMC numbers increased, which was attenuated in tissues from OPN-deficient mice. Furthermore, VSMC proliferation and OPN expression induced by PDGF were attenuated dose-dependently by ICB (10 or 30 μg/ml). Reporter assays conducted using OPN promoter-luciferase constructs showed that the promoter region 538-234 bp of the transcription start site was responsible for transcriptional activity enhancement by PDGF, which was significantly inhibited by ICB. Putative binding sites for AP-1 and C/EBPβ in the indicated promoter region were suggested by TF Search, and increased binding of AP-1 and C/EBPβ in PDGF-treated VSMCs was demonstrated using a ChIP assay. The increased bindings of AP-1 and C/EBPβ into OPN promoter were attenuated by ICB. Moreover, the PDGF-induced expression of OPN was markedly attenuated in VSMCs transfected with siRNA for AP-1 and C/EBPβ. These results indicate that ICB inhibit VSMC proliferation by inhibiting the AP-1 and C/EBPβ signaling pathways and thus downregulating OPN expression.