We have previously shown that
carboxymethyl dextran benzylamide (
CMDB7), a
heparin-like molecule, inhibits the growth of
tumors xenografted in nude mice, angiogenesis, and
metastasis by altering the binding of angiogenic
growth factors, including
platelet-derived growth factor,
transforming growth factor beta, and
fibroblast growth factor 2, to their specific receptors. In this study, we explore the effect of
CMDB7 on the most specific angiogenic
growth factor,
vascular endothelial growth factor 165 (
VEGF(165)). We demonstrate here that
CMDB7 inhibits the mitogenic effect of
VEGF(165) on human umbilical vein endothelial cells (HUV-ECs) by preventing the VEGF(165)-induced
VEGF receptor-2 (KDR) autophosphorylation and consequently a specific intracellular signaling. In competition experiments, the binding of (125)I-VEGF(165) to HUV-ECs is inhibited by
CMDB7 with an IC(50) of 2 microm. Accordingly,
CMDB7 inhibits the cross-linking of (125)I-VEGF(165) to the surface of HUV-ECs, causing the disappearance of both labeled complexes, 170-180 and 240-250 kDa. We show that
CMDB7 increases the electrophoretic mobility of
VEGF(165), thus evidencing formation of a stable complex with this factor. Moreover,
CMDB7 reduces the (125)I-VEGF(165) binding to coated
heparin-
albumin and prevents a
heparin-induced increase in iodinated
VEGF(165) binding to soluble (125)I-KDR-Fc chimera. Concerning KDR,
CMDB7 has no effect on (125)I-KDR-Fc electrophoretic migration and does not affect labeled KDR-Fc binding to coated
heparin-
albumin. In the presence of
VEGF(165), (125)I-KDR-Fc binding to
heparin is enhanced, and under these conditions,
CMDB7 interferes with KDR binding. These data indicate that
CMDB7 effectively inhibits the
VEGF(165) activities by interfering with
heparin binding to
VEGF(165) and
VEGF(165).KDR complexes but not by direct interactions with KDR.