Inhibition of in vitro angiogenesis by platelet factor-4-derived peptides and mechanism of action

In this study, we examined in detail the interaction of platelet factor-4 ( PF-4) with fibroblast growth factor-2 (FGF-2) and vascular endothelial grow th factor (VEGF) and the effect of PF-4-derived synthetic peptides. We show that a peptide between amino acids 47 and 70 that contains the heparin-bin ding lysine-rich site inhibits FGF-2 or VEGF function. This is based on the following observations: PF-4 peptide 47-70 inhibited FGF-2 or VEGF binding to endothelial cells; it inhibited FGF-2 or VEGF binding to FGFRs or VEGFR s in heparan sulfate-deficient CHO cells transfected with FGFR1 (CHOFGFR1) or VEGFR2 (CHOmVEGFR2) cDNA; it blocked proliferation or tube formation in three-dimensional angio-genesis assays; and, finally, it competed with the direct association of I-125-PF-4 With FGF-2 or VEGF, respectively, and inhi bited heparin-induced FGF-P dimerization. A shorter C-terminal peptide (pep tide 58-70), which still contained the heparin-binding lysin rich site, had no effect. Peptide 17-58, which is located in the central part of the mole cule, although it does not inhibit FGF-2 or VEGF binding or biologic activi ty in endothelial cells, inhibited heparin-dependent binding of I-125-FGF-2 or I-125-VEGF to CHOmFGFR1 or CHOmVEGFR2 cells, respectively. Shorter pept ides (peptides 34-58 and 47-58) did not show any of these effects. (C) 1999 by The American Society of Hematology.