Journal of Biological Chemistry
Volume 272, Issue 50, 12 December 1997, Pages 31582-31588
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CELL BIOLOGY AND METABOLISM
Inhibition of Vascular Endothelial Growth Factor (VEGF)-induced Endothelial Cell Proliferation by a Peptide Corresponding to the Exon 7-Encoded Domain of VEGF165*

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Vascular endothelial growth factor (VEGF) is a potent mitogen for endothelial cells (EC) in vitro and a major regulator of angiogenesis in vivo. VEGF121 and VEGF165 are the most abundant of the five known VEGF isoforms. The structural difference between these two is the presence in VEGF165 of 44 amino acids encoded by exon 7 lacking in VEGF121. It was previously shown that VEGF165 and VEGF121 both bind to KDR/Flk-1 and Flt-1 but that VEGF165 binds in addition to a novel receptor (Soker, S., Fidder, H., Neufeld, G., and Klagsbrun, M. (1996)J. Biol. Chem. 271, 5761–5767). The binding of VEGF165 to this VEGF165-specific receptor (VEGF165R) is mediated by the exon 7-encoded domain. To investigate the biological role of this domain further, a glutathioneS-transferase fusion protein corresponding to the VEGF165 exon 7-encoded domain was prepared. The fusion protein inhibited binding of125I-VEGF165 to VEGF165R on human umbilical vein-derived EC (HUVEC) and MDA-MB-231 tumor cells. The fusion protein also inhibited significantly125I-VEGF165 binding to KDR/Flk-1 on HUVEC but not on porcine EC which express KDR/Flk-1 alone. VEGF165had a 2-fold higher mitogenic activity for HUVEC than did VEGF121. The exon 7 fusion protein inhibited VEGF165-induced HUVEC proliferation by 60% to about the level stimulated by VEGF121. Unexpectedly, the fusion protein also inhibited HUVEC proliferation in response to VEGF121. Deletion analysis revealed that a core inhibitory domain exists within the C-terminal 23-amino acid portion of the exon 7-encoded domain and that a cysteine residue at position 22 in exon 7 is critical for inhibition. It was concluded that the exon 7-encoded domain of VEGF165 enhances its mitogenic activity for HUVEC by interacting with VEGF165R and modulating KDR/Flk-1-mediated mitogenicity indirectly and that exon 7-derived peptides may be useful VEGF antagonists in angiogenesis-associated diseases.

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This work was supported by National Institutes of Health Grants CA37392 and GM47397 (to M. K.), a research award from the Association for the Cure of Cancer of the Prostate (Cap CURE) (to M. K.), and funds from the “De Drie Lichten” and “Dr. Saal van Zwanenberg Stichting” Foundations (to H. F.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.