Identification of a peptide antagonist of the <scp>FGF</scp> 1– <scp>FGFR</scp> 1 signaling axis by phage display selection

Overexpression of fibroblast growth factor receptor 1 (FGFR1) is a common aberration in lung and breast cancers and has necessitated the design of drugs targeting FGFR1-dependent downstream signaling and FGFR1 ligand binding. To date, the major group of drugs being developed for treatment of FGFR1-dependent cancers are small-molecule tyrosine kinase inhibitors; however, the limited specificity of these drugs has led to increasing attempts to design molecules targeting the extracellular domain of FGFR1. Here, we used the phage display technique to select cyclic peptides F8 (ACSLNHTVNC) and G10 (ACSAKTTSAC) as binders of the fibroblast growth factor 1 (FGF1)-FGFR1 interface. ELISA and in vitro cell assays were performed to reveal that cyclic peptide F8 is more effective in preventing the FGF1-FGFR1 interaction, and also decreases FGF1-induced proliferation of BA/F3 FGFR1c cells by over 40%. Such an effect was not observed for BA/F3 cells lacking FGFR1. Therefore, cyclic peptide F8 can act as a FGF1-FGFR1 interaction antagonist, and may be suitable for further development for potential use in therapies against FGFR1-expressing cancer cells.