Abstract
Inhibition of tumor neovascularization has profound effects on the growth of solid tumors. An endothelial cell-specific cytotoxic conjugate was prepared by chemically linking recombinant vascular endothelial growth factor (VEGF165) and a truncated diphtheria toxin molecule (DT385). The treatment of subconfluent cultures of human umbilical vein endothelial cells and human microvascular endothelial cells with the VEGF165-DT385 conjugate resulted in a selective, dose-dependent inhibition of growth. Parallel experiments with either the free toxin or a mixture of VEGF and the toxin polypeptide did not affect proliferation (DNA synthesis) of these cells. The selective cytotoxicity correlated with the appropriate receptor expression (KDR/flk-1 positive) on the target cells. VEGF-toxin conjugate inhibited the growth of a murine hemangioma-derived endothelial cell line (Py-4-1), which was positive for flk-1 expression. Under similar conditions, the conjugate did not affect the proliferation of a receptor-negative ovarian cancer cell line in vitro. In an in vivo model of angiogenesis, the VEGF165-DT385 conjugate blocked basic fibroblast growth factor-induced neovascularization of the chick chorioallantoic membrane. These studies demonstrate the successful targeting of a cytotoxic polypeptide to proliferating vascular endothelial cells (normal and tumorigenic) and the potential utility of such conjugates in blocking tumor neovascularization.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Cell Division / drug effects
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Cells, Cultured
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DNA / biosynthesis
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DNA / drug effects
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Diphtheria Toxin / administration & dosage
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Diphtheria Toxin / pharmacology*
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Dose-Response Relationship, Drug
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Drug Screening Assays, Antitumor
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Endothelial Growth Factors / administration & dosage
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Endothelial Growth Factors / pharmacology*
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Endothelium, Vascular / chemistry
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Endothelium, Vascular / cytology
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Endothelium, Vascular / drug effects*
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Female
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Fibroblast Growth Factor 2 / pharmacology
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Hemangioma / blood supply*
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Hemangioma / chemistry
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Humans
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Immunotoxins / administration & dosage
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Immunotoxins / pharmacology*
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Lymphokines / administration & dosage
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Lymphokines / pharmacology*
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Mice
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Neovascularization, Pathologic / prevention & control*
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Neovascularization, Physiologic / drug effects*
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Ovarian Neoplasms / blood supply
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Ovarian Neoplasms / chemistry
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Receptor Protein-Tyrosine Kinases*
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Receptors, Growth Factor*
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Receptors, Vascular Endothelial Growth Factor
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Tumor Cells, Cultured
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Umbilical Cord / blood supply
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Vascular Endothelial Growth Factor A
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Vascular Endothelial Growth Factors
Substances
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Diphtheria Toxin
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Endothelial Growth Factors
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Immunotoxins
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Lymphokines
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Receptors, Growth Factor
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VEGFA protein, human
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Vascular Endothelial Growth Factor A
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Vascular Endothelial Growth Factors
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Fibroblast Growth Factor 2
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DNA
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Receptor Protein-Tyrosine Kinases
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Receptors, Vascular Endothelial Growth Factor