title: Insulin-like growth factor binding protein-related protein 1 mediates VEGF-induced proliferation, migration and tube formation of retinal endothelial cells.
abstract: OBJECTIVE
  The potential role of insulin-like growth factor binding protein-related protein 1 (IGFBP-rP1) as an endogenous angiogenesis inhibitor in the prevention of vascular endothelial growth factor (VEGF)-induced retinal angiogenesis has not been explored.
  
  
  METHODS
  Expression of IGFBP-rP1 in rhesus macaque choroid-retinal endothelial cell line (RF/6A) cells was assessed by reverse transcription polymerase chain reaction analysis and Western blotting. RF/6A cells were treated with VEGF (10 ng/ml) alone or in the presence of IGFBP-rP1 at concentrations ranging from 50 ng/ml to 200 ng/ml. The proliferation, migration and capillary-like tube formation of RF/6A cells were evaluated using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium colorimetric assay, the chemotactic motility assay and the Matrigel tube formation assay, respectively. Flow cytometry was used to detect the apoptosis of RF/6A cells, and oncogenic B-Raf expression was assessed to elucidate the pathway for IGFBP-rP1-mediated induction of apoptosis in the presence of VEGF.
  
  
  RESULTS
  RF/6A cells expressed both IGFBP-rP1 transcripts and IGFBP-rP1 protein. VEGF markedly stimulated proliferation, migration and capillary-like tube formation of RF/6A cells (P<0.05), whereas those VEGF-induced parameters were significantly inhibited by IGFBP-rP1 at concentrations ranging from 50 ng/ml to 200 ng/ml in a dose-dependent manner (P < 0.05). Following addition of IGFBP-rP1, expression of B-Raf was significantly decreased dose-dependently, and apoptosis occurred as evidenced by flow cytometry (P < 0.05).
  
  
  CONCLUSIONS
  IGFBP-rP1 can inhibit the stimulatory effect of VEGF on retinal angiogenesis in vitro by inhibiting expression of B-Raf to induce apoptosis. It is a novel endogenous anti-angiogenic factor with potential therapeutic action in retinal neovascularization dependent disorders.
authors.affiliation: Department of Ophthalmology, Affiliated First People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China.
authors.forename: Tao
authors.initials: T
authors.lastname: Sun
authors.forename: Hui
authors.initials: H
authors.lastname: Cao
authors.forename: Lin
authors.initials: L
authors.lastname: Xu
authors.forename: Bijun
authors.initials: B
authors.lastname: Zhu
authors.forename: Qing
authors.initials: Q
authors.lastname: Gu
authors.forename: Xun
authors.initials: X
authors.lastname: Xu
mesh_terms: D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D003124:Colorimetry; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005434:Flow Cytometry; D018969:Insulin-Like Growth Factor Binding Proteins / Q000502:physiology*; D008253:Macaca mulatta; D048493:Proto-Oncogene Proteins B-raf / Q000378:metabolism; D015861:Retinal Neovascularization / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control*; D012171:Retinal Vessels / Q000166:cytology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*
chemical_list: D018969:Insulin-Like Growth Factor Binding Proteins; D042461:Vascular Endothelial Growth Factor A; C102529:insulin-like growth factor binding protein-related protein 1; D048493:Proto-Oncogene Proteins B-raf