OBJECTIVETo develop toxin targeting vascular endothelial growth factor receptor II (VEGF-II/KDR) fused with a KDR-binling peptide screened from peptide library.

METHODSBy affinity to KDR molecular which expressed specifically by new born vascular endothelial cell, peptides to KDR were screened from C7 peptide library by phage display. Among them, a peptide binding to KDR with high affinity termed as P5 was selected and fused to the N-terminal of Shiga toxin subunit A (StxA). The protein (P5-StxA) was expressed in E. coli.

RESULTSELISA and Western blot were applied to characterize the binding interaction between the fusion protein, P5-StxA and KDR. Cytotoxicity assay showed that P5-StxA maintained similar toxicity to cell as StxA. In the model of angiogenesis, P5-StxA inhibited selectively VEGF-induced growth of preexisting vessels of the chick chorioallantoic membrane.

CONCLUSIONThese studies demonstrate the small peptide, P5, maybe be used as carrier of toxin targeting to KDR.