Sulpice Eric, Bryckaert Marijke, Lacour Julie, Contreres Jean-Olivier, Tobelem Gerard
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.
Blood. 2002 Nov 1;100(9):3087-94. doi: 10.1182/blood.V100.9.3087.
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.
血小板因子4（PF - 4）是趋化因子家族的一员，具有强大的抗血管生成特性。PF - 4抑制内皮细胞增殖的机制尚不清楚。我们研究了PF - 4对碱性成纤维细胞生长因子（FGF2）诱导的细胞内信号转导的影响。我们发现PF - 4（10微克/毫升）抑制了FGF2诱导的肾上腺皮质毛细血管内皮（ACE）细胞的增殖。PD98059对MEK1/2（丝裂原活化蛋白激酶激酶）的抑制或Ly294002对PI3K（磷脂酰肌醇3 -激酶）的抑制消除了FGF2诱导的增殖，这表明ACE细胞增殖需要通过细胞外信号调节激酶（ERK）和PI3K途径的双重信号传导。Ly294002对ERK磷酸化没有显著影响，而PD98059对Akt磷酸化有微弱影响，这表明ACE细胞增殖需要两个独立的级联反应。添加PF - 4（10微克/毫升）显著抑制了ERK磷酸化（95%），表明PF - 4直接作用于该激酶或其上游。令人惊讶的是，PF - 4不影响FGF2诱导的Akt磷酸化。这表明PF - 4通过细胞内抑制机制破坏FGF2信号传导。为了排除PF - 4仅抑制FGF2与一种FGF受体的结合、优先激活ERK途径的可能性，我们使用转染了FGF - R1 cDNA的突变硫酸乙酰肝素缺陷型中国仓鼠卵巢细胞研究了PF - 4对FGF2诱导的ERK和Akt磷酸化的影响。添加PF - 4（1微克/毫升）显著抑制了ERK磷酸化（90%），对Akt磷酸化没有影响，这表明PF - 4作用于FGF - R1受体的下游。总之，这是首次报道表明PF - 4在其受体下游抑制FGF2活性。
