Identification Of Peptides Blocking The Tumor Vascular Growth Factor Receptor And The Construction Of Tumor Vaccine

[Objective] Tumor angiogensis is a critical step for the growth and metastasis of solid tumors. Vascular endothelial growth factor (VEGF) is a specific and potent angiogenic factor that mediates vascularization by binding to the kinase domain receptor (KDR). In this study we screen the phage-epitope library in attempt to predict the receptor recognition site on VEGF, identify peptide able to block the interaction of VEGF-KDR and find a potent vaccine against tumor angiogenesis by targeting VEGF.[Methods] Two phage-epitope libraries were screened with two anti-VEGF neutralizing monoclonal antibodies- JH121 and VG189, The clones were tested by dot blotting and ELISA. And the positive clones were used as the immunogens to immunize mice. Both of the serum and phage peptides were add to measure their effects on the growth of HUVEC (human umbilical vascular endothelial cell).[Results] All the selected clones gave strong signal in dot bloting and ELISA . the 7mer peptide and 12 mer peptide selected from the peptide library elicited strong anti-VEGF antibody immuno-reaction in mice . DNA sequenseing showed that GWYYDAL and VASAVFYSALVE mimic the discontinuous epitope of VEGF by the 14- 17, 21 and 21 25 amino acid residues respectively. The antibody induced by peptide GWYYDAL abolished VEGF-induced HUVEC growth in dose dependent which specifically express the KDR. Moreover, both of the peptide GWYYDAL and VASAVFYSALVE displaying on phage also inhibited the growth of HUVEC.[Conclusion] Taken together, these data suggested that two peptides GWYYDAL and VASAVFYSALVE were effective mimickers of VEGF and these peptides maybe potent inhibitors of KDR and offer a hope for the construction of tumor vaccine.