Bovine lactoferricin inhibits basic fibroblast growth factor- and vascular endothelial growth factor₁₆₅-induced angiogenesis by competing for heparin-like binding sites on endothelial cells

Angiogenesis is a complex process whereby new blood vessels form from pre-existing vasculature in response to proangiogenic factors such as basic fibroblast growth factor (bFGF) and the 165-kd isoform of vascular endothelial growth factor (VEGF₁₆₅). Angiogenesis inhibitors show considerable potential in the treatment of cancer because angiogenesis is necessary for tumor growth beyond a few millimeters in diameter because of the tumor's need for oxygen and nutrient supply, as well as waste removal. Bovine lactoferricin (LfcinB) is a peptide fragment of iron- and heparin-binding lactoferrin obtained from cow's milk. Here we provide in vivo and in vitro evidence that LfcinB has potent antiangiogenic activity. LfcinB strongly inhibited both bFGF- and VEGF₁₆₅-induced angiogenesis in Matrigel plugs implanted in C57BL/6 mice. In addition, LfcinB inhibited the in vitro proliferation and migration of human umbilical vein endothelial cells (HUVECs) in response to bFGF or VEGF ₁₆₅ but was not cytotoxic to HUVECs. Rather, LfcinB complexed with heparin-like structures on the HUVEC surface that are involved in the binding of bFGF and VEGF₁₆₅ to their respective receptors, thereby preventing receptor-stimulated angiogenesis. These findings suggest that LfcinB may have utility as an antiangiogenic agent for the treatment of human cancers.