The 6-AH family [D-Nle-X-Ile-NH-(CH(2))(5)-CONH(2); where X = various amino acids] of angiotensin IV (Ang IV) analogs binds directly to hepatocyte growth factor (HGF) and inhibit HGF's ability to form functional dimers. The metabolically stabilized 6-AH family member, D-Nle-Tyr-Ile-NH-(CH(2))(5)-CONH(2,) had a t(1/2) in blood of 80 min compared with the parent compound norleual [Nle-Tyr-Leu-Ψ-(CH(2)-NH(2))(3-4)-His-Pro-Phe], which had a t(1/2) in blood of <5 min. 6-AH family members were found to act as mimics of the dimerization domain of HGF (hinge region) and inhibited the interaction of an HGF molecule with a (3)H-hinge region peptide resulting in an attenuated capacity of HGF to activate its receptor Met. This interference translated into inhibition of HGF-dependent signaling, proliferation, and scattering in multiple cell types at concentrations down into the low picomolar range. We also noted a significant correlation between the ability of the 6-AH family members to block HGF dimerization and inhibition of the cellular activity. Furthermore, a member of the 6-AH family with cysteine at position 2, was a particularly effective antagonist of HGF-dependent cellular activities. This compound suppressed pulmonary colonization by B16-F10 murine melanoma cells, which are characterized by an overactive HGF/Met system. Together, these data indicate that the 6-AH family of Ang IV analogs exerts its biological activity by modifying the activity of the HGF/Met system and offers the potential as therapeutic agents in disorders that are dependent on or possess an overactivation of the HGF/Met system.