Epitope Mapping Of BFGF By PhageDisplay And Functional Analysis Of The Epitope Peptides

Basic fibroblast growth factor (bFGF) is a potent mitogen and it has been found that high expression of bFGF is closely related to the angiogenesis in various cancers and tumors. bFGF is well known to bind to its cell surface receptors with high affinity and in a heparin dependent manner. In attempt to predict the receptor recognition site on bFGF and find a potential vaccine against tumor angiogenesis by targeting bFGF, we screen phage display-epitope library with monoclonal antibody GF22, which neutralize the bioactivities of bFGF. On the affinity isolated phages we identified the epitopes shared a highly consensus sequence (Leu-Pro-Pro/Leu-GIy-His-Phe/ile-Lys). Sequence analysis showed that this epitope is found in two location within bFGF molecule: one is continuous protein sequence at amino acids 22-27 (PPGHFK), and the other is a discontinuous epitope composed by amino acid 45P, 58P and core sequence HIK at 59-61. Phage clones with GF22 epitope specifically inhibit bFGF binding to GF22 and can highly induce immuno-response in mice. Combining the previous report that synthetic peptide with sequence PPGHFK inhibits bFGF binding to its receptor and inhibit bFGF-induced proliferation of vascular endothelial cells, we further suggest that amino acid His, lie and Lys at 59,6O,61 may constitute part of the receptor binding site, and peptide with sequence LPLGHIK might be a potential vaccine against bFGF.