Endostatin binds to blood vessels in situ independent of heparan sulfate and does not compete for fibroblast growth factor-2 binding

Am J Pathol. 1999 Jul;155(1):71-6. doi: 10.1016/S0002-9440(10)65101-2.


Endostatin is a carboxyl-terminal proteolytic fragment of collagen XVIII and a potent inhibitor of angiogenesis. The mechanism of action is unknown, but the crystal structure of endostatin predicts a prominent heparan sulfate binding site, suggesting that endostatin competitively inhibits heparin-binding angiogenic factors, such as basic fibroblast growth factor (FGF-2). The goal of the study was to map endostatin binding sites in intact human tissues and to determine whether this binding is heparan sulfate dependent. In situ binding was performed with recombinant epitope-tagged murine endostatin. Endostatin predominantly binds to blood vessels of different calibers in a saturable fashion. In addition, binding to some epithelial basement membranes is seen. The localization pattern is similar to that reported for collagen XVIII, endostatin's parent molecule. In breast carcinomas, endostatin co-localizes largely with FGF-2. In a surprising contrast to FGF-2, endostatin binding is resistant to treatment with heparitinase, demonstrating that binding is not mediated by heparan sulfate proteoglycans. Furthermore, FGF-2 and heparin do not compete for endostatin binding, providing additional evidence for the discreteness of endostatin and FGF-binding sites.

MeSH terms

  • Basement Membrane / metabolism
  • Binding Sites / physiology
  • Binding, Competitive
  • Blood Vessels / metabolism*
  • Collagen / metabolism*
  • Collagen Type XVIII
  • Drug Resistance
  • Endostatins
  • Fibroblast Growth Factor 2 / metabolism*
  • Heparitin Sulfate / pharmacology*
  • Humans
  • Peptide Fragments / metabolism*
  • Polysaccharide-Lyases / pharmacology
  • Recombinant Proteins


  • Collagen Type XVIII
  • Endostatins
  • Peptide Fragments
  • Recombinant Proteins
  • Fibroblast Growth Factor 2
  • Collagen
  • Heparitin Sulfate
  • Polysaccharide-Lyases
  • heparitinsulfate lyase