title: The proangiogenic phenotype of tumor-derived endothelial cells is reverted by the overexpression of platelet-activating factor acetylhydrolase.
abstract: OBJECTIVE
  We previously reported that human tumor-derived endothelial cells (TEC) have an angiogenic phenotype related to the autocrine production of several angiogenic factors. The purpose of the present study was to evaluate whether an enhanced synthesis of platelet-activating factor (PAF) might contribute to the proangiogenic characteristics of TEC and whether its inactivation might inhibit angiogenesis.
  
  
  METHODS
  To address the potential role of PAF in the proangiogenic characteristics of TEC, we engineered TEC to stably overexpress human plasma PAF-acetylhydrolase (PAF-AH), the major PAF-inactivating enzyme, and we evaluated in vitro and in vivo angiogenesis.
  
  
  RESULTS
  TECs were able to synthesize a significantly enhanced amount of PAF compared with normal human microvascular endothelial cells when stimulated with thrombin, vascular endothelial growth factor, or soluble CD154. Transfection of TEC with PAF-AH (TEC-PAF-AH) significantly inhibited apoptosis resistance and spontaneous motility of TEC. In addition, PAF and vascular endothelial growth factor stimulation enhanced the motility and adhesion of TEC but not of TEC-PAF-AH. In vitro, TEC-PAF-AH lost the characteristic ability of TEC to form vessel-like structures when plated on Matrigel. Finally, when cells were injected s.c. within Matrigel in severe combined immunodeficiency mice or coimplanted with a renal carcinoma cell line, the overexpression of PAF-AH induced a significant reduction of functional vessel formation.
  
  
  CONCLUSIONS
  These results suggest that inactivation of PAF, produced by TEC, by the overexpression of plasma PAF-AH affects survival, migration, and the angiogenic response of TEC both in vitro and in vivo.
authors.affiliation: Department of Internal Medicine, Centre for Molecular Biotechnology, University of Turin, Turin, Italy.
authors.forename: Sophie
authors.initials: S
authors.lastname: Doublier
authors.forename: Monica
authors.initials: M
authors.lastname: Ceretto
authors.forename: Enrico
authors.initials: E
authors.lastname: Lupia
authors.forename: Stefania
authors.initials: S
authors.lastname: Bravo
authors.forename: Benedetta
authors.initials: B
authors.lastname: Bussolati
authors.forename: Giovanni
authors.initials: G
authors.lastname: Camussi
mesh_terms: D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase / Q000096:biosynthesis* / Q000737:chemistry; D000818:Animals; D023201:CD40 Ligand / Q000096:biosynthesis; D045744:Cell Line, Tumor; D042783:Endothelial Cells / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D051379:Mice; D016513:Mice, SCID; D008954:Models, Biological; D009369:Neoplasms / Q000378:metabolism / Q000473:pathology*; D009389:Neovascularization, Pathologic; D010972:Platelet Activating Factor / Q000737:chemistry; D013917:Thrombin / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D010972:Platelet Activating Factor; D042461:Vascular Endothelial Growth Factor A; D023201:CD40 Ligand; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D013917:Thrombin