title: Platelet factor 4 inhibits FGF2-induced endothelial cell proliferation via the extracellular signal-regulated kinase pathway but not by the phosphatidylinositol 3-kinase pathway.
abstract: Platelet factor 4 (PF-4) is a member of the chemokine family with powerful antiangiogenic properties. The mechanism by which PF-4 inhibits endothelial cell proliferation is unclear. We investigated the effects of PF-4 on the intracellular signal transduction induced by basic fibroblast growth factor (FGF2). We found that PF-4 (10 microg/mL) inhibited the FGF2-induced proliferation of adrenal cortex capillary endothelial (ACE) cells. The inhibition of MEK1/2 (mitogen-activated protein kinase kinase) by PD98059 or of PI3K (phosphatidylinositol 3-kinase) by Ly294002 abolished the proliferation induced by FGF2, suggesting that ACE cell proliferation required dual signaling through both the extracellular signal-regulated kinase (ERK) and PI3K pathways. Ly294002 had no significant effect on ERK phosphorylation, whereas PD98059 had a weak effect on the phosphorylation of Akt, suggesting that 2 separate cascades are required for ACE cell proliferation. The addition of PF-4 (10 microg/mL) significantly inhibited ERK phosphorylation (95%), showing that PF-4 acted directly on or upstream from this kinase. Surprisingly, PF-4 did not affect FGF2-induced Akt phosphorylation. This suggests that PF-4 disrupts FGF2 signaling via an intracellular mechanism of inhibition. To exclude the possibility that PF-4 inhibited the binding of FGF2 to only one FGF receptor, preferentially activating the ERK pathway, we investigated the effect of PF-4 on FGF2-induced ERK and Akt phosphorylation, using mutant heparan sulfate-deficient Chinese hamster ovary cells transfected with the FGF-R1 cDNA. The addition of PF-4 (1 microg/mL) significantly inhibited ERK phosphorylation (90%), with no effect on Akt phosphorylation, suggesting that PF-4 acts downstream from the FGF-R1 receptor. In conclusion, this is the first report showing that PF-4 inhibits FGF2 activity downstream from its receptor.
authors.affiliation: Institut des Vaisseaux et du Sang (IVS), Centre de Recherche de l'Association Claude Bernard, Hôpital Lariboisière, 8 Rue Guy Patin, 75475 Paris cedex 10, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Sulpice
authors.forename: Marijke
authors.initials: M
authors.lastname: Bryckaert
authors.forename: Julie
authors.initials: J
authors.lastname: Lacour
authors.forename: Jean-Olivier
authors.initials: JO
authors.lastname: Contreres
authors.forename: Gerard
authors.initials: G
authors.lastname: Tobelem
mesh_terms: D000302:Adrenal Cortex / Q000098:blood supply; D000818:Animals; D016466:CHO Cells; D002196:Capillaries / Q000166:cytology; D002455:Cell Division / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D006224:Cricetinae; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016222:Fibroblast Growth Factor 2 / Q000037:antagonists & inhibitors*; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D010978:Platelet Factor 4 / Q000235:genetics / Q000494:pharmacology*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D020794:Receptor Protein-Tyrosine Kinases / Q000187:drug effects / Q000235:genetics; D051496:Receptor, Fibroblast Growth Factor, Type 1; D017468:Receptors, Fibroblast Growth Factor / Q000187:drug effects / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D014162:Transfection
chemical_list: D002867:Chromones; D004791:Enzyme Inhibitors; D016222:Fibroblast Growth Factor 2; D005419:Flavonoids; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010978:Platelet Factor 4; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D020794:Receptor Protein-Tyrosine Kinases; D051496:Receptor, Fibroblast Growth Factor, Type 1; D017468:Receptors, Fibroblast Growth Factor; D011993:Recombinant Fusion Proteins; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C482128:MAP2K2 protein, human; C496348:FGFR1 protein, human; C496349:Fgfr1 protein, mouse; C494918:AKT1 protein, human; C482125:MAP2K1 protein, human; C482127:Map2k1 protein, mouse; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one