Effect of HGF-like basic hexapeptides on angiogenesis.

The interaction of glycosaminoglycans (GAG) with peptides relies on noncovalent binding to basic amino acid sequences, for which a minimal requirement is a pentapeptide region in the protein and the sulfated and carboxyl region in the GAG. Since such sequences are present in the heparin-binding angiogenic cytokines, including hepatocyte growth factor (HGF), we have postulated that such small peptides may have biological activity. Two basic peptide regions of the beta chain of HGF (RYRNKH512-516, HHRGK645-649) exhibited significant antiangiogenic activity in vivo in the chorioallantoic membrane assay and showed some antiproliferative activity in vitro on normal human brain microvessel endothelial-but not on anchorage-independent endothelial-cells (Kaposi sarcoma). Basic HIV-TAT peptides and scrambled hexapeptides did not show similar activity, except for KRKRKR, indicating sequence specificity of the phenomena. An HGF-derived basic peptide, HHRGK, modulated tumor-induced angiogenesis in vivo by interfering with the morphogenic, but not with the proliferative, phase of the process. These observations suggest small basic peptides as a new class of angiogenesis modulators.