Endostatin inhibits VEGF-induced endothelial cell migration and tumor growth independently of zinc binding

Endostatin, produced as recombinant protein in human 293-EBNA cells, inhibits the migration of human umbilical vein endothelial cells (HUVECs) in response to vascular endothelial growth factor (VEGF) in a dose-dependent manner and prevents the subcutaneous growth of human renal cell carcinomas in nude mice at concentrations and in doses that are from 1000- to 100 000-fold lower than those previously reported. The inhibition of migration is not affected by mutations which eliminate Zn or heparin binding and inhibition of tumor growth does not depend on Zn binding. The results of the migration assays suggest that endostatin causes a block at one or more steps in VEGF-induced migration, while VEGF in turn can cause a block of the inhibition by endostatin of VEGF-induced migration of HUVECs.