Abstract:
As a small affinity molecule to serve as an alternative
to antibodies, we have developed a conformationally constrained
peptide with a de novo designed helix−loop−helix (HLH) scaffold.
To evaluate its potential for biomedical applications, we performed
directed evolution of HLH peptides to obtain an inhibitor for
vascular endothelial growth factor-A (VEGF). A phage-displayed
library of HLH peptides was constructed and screened against
VEGF, giving the peptide VS42 that inhibits the VEGF/VEGF
receptor-2 interaction (IC50 = 210 nM), which was further
improved by in vitro affinity maturation using a yeast-displayed
library. An identified HLH peptide, VS42-LR3, exhibited improved
inhibitory activity (IC50 = 37 nM), high thermal stability, and
excellent resistance against chemical denaturation. In biological activity tests, the HLH peptide was found to block VEGF-induced
proliferation of human umbilical vein endothelial cells and suppress tumor growth in a murine xenograft model of human colorectal
cancer.