title: Triptolide inhibits rat vascular smooth muscle cell proliferation and cell cycle progression via attenuation of ERK1/2 and Rb phosphorylation.
abstract: BACKGROUND
  Drug-eluting stents have demonstrated a substantial reduction of restenosis and currently are gaining a leading position in the intervention field. Triptolide, a purified extract from Chinese herb medicine Tripterygium wilfordii hook F, exhibits antiproliferative and pro-apoptotic function in vitro and in vivo. In the present study, we investigated effects of triptolide on in-stent restenosis in vivo and in vitro, and study the biological mechanism of this drug.
  
  
  METHODS
  Rat aortic smooth muscle cells were cultured and treated with different concentration of triptolide (0, 1, 10, and 50nM). For cell viability, we used trypan blue exclusion (TBE) survival assay. Flow cytometry was used to study the influence of triptolide on VSMCs cell cycle. Signal proteins were detected by western blotting analysis. Triptolide coated stents had been implanted in the iliac arteries of New Zealand rabbits. After 4weeks, the stented iliac artery segments were processed for embedding, staining and histomorphometric analysis.
  
  
  RESULTS
  Triptolide of concentration 10nM, 50nM significantly inhibited fetal calf serum-induced VSMC proliferation (p<0.05). The accumulation of triptolide-treated cells at the G1/S-interphase was dose dependent. Triptolide completely blocked the cell cycle progression at 50nM. Western blotting analysis showed decreased ERK1/2 MAP kinase phosphorylation level, significantly increased p21(cip1) expression and reduced retinoblastoma protein (pRb) phosphorylation after 24h of triptolide treatment. 4weeks after the surgery, the arterial wall morphology was shown that triptolide-coated stent has less neointimal vs bare metal stent.
  
  
  CONCLUSIONS
  Our study indicates that triptolide exert inhibitory effect on VSMC proliferation, inactivation of MAPK pathway and modulation of cell cycle proteins p21(cip1) and Rb are relating mechanisms. Triptolide drug-eluting stents attenuated neointimal formation after stent implantation in rabbit vessel. We believe that triptolide may potentially be useful in treating cardiovascular restenosis after PCI.
authors.affiliation: Department of Cardiology, Ruijin Hospital, Jiao Tong University, Shanghai 200025, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Tao
authors.forename: Lin
authors.initials: L
authors.lastname: Lu
authors.forename: Ruiyan
authors.initials: R
authors.lastname: Zhang
authors.forename: Jian
authors.initials: J
authors.lastname: Hu
authors.forename: Jingwei
authors.initials: J
authors.lastname: Ni
authors.forename: Weifeng
authors.initials: W
authors.lastname: Shen
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004224:Diterpenes / Q000494:pharmacology*; D054855:Drug-Eluting Stents; D004852:Epoxy Compounds / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D007083:Iliac Artery / Q000187:drug effects / Q000473:pathology; D008297:Male; D008954:Models, Biological; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D032389:Myocytes, Smooth Muscle / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D010616:Phenanthrenes / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D016160:Retinoblastoma Protein / Q000378:metabolism*
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; D004224:Diterpenes; D004852:Epoxy Compounds; D010616:Phenanthrenes; D016160:Retinoblastoma Protein; C001899:triptolide; D048049:Extracellular Signal-Regulated MAP Kinases