title: Vascular endothelial growth factor-toxin conjugate specifically inhibits KDR/flk-1-positive endothelial cell proliferation in vitro and angiogenesis in vivo.
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.
authors.affiliation: Department of Pharmacology, University of Minnesota, Minneapolis, 55455, USA.
authors.forename: S
authors.initials: S
authors.lastname: Ramakrishnan
authors.forename: T A
authors.initials: TA
authors.lastname: Olson
authors.forename: V L
authors.initials: VL
authors.lastname: Bautch
authors.forename: D
authors.initials: D
authors.lastname: Mohanraj
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis / Q000187:drug effects; D004167:Diphtheria Toxin / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D016228:Endothelial Growth Factors / Q000008:administration & dosage / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000737:chemistry / Q000166:cytology / Q000187:drug effects*; D005260:Female; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D006391:Hemangioma / Q000098:blood supply* / Q000737:chemistry; D006801:Humans; D000922:Immunotoxins / Q000008:administration & dosage / Q000494:pharmacology*; D008222:Lymphokines / Q000008:administration & dosage / Q000494:pharmacology*; D051379:Mice; D009389:Neovascularization, Pathologic / Q000517:prevention & control*; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D010051:Ovarian Neoplasms / Q000098:blood supply / Q000737:chemistry; D020794:Receptor Protein-Tyrosine Kinases; D017978:Receptors, Growth Factor; D040262:Receptors, Vascular Endothelial Growth Factor; D014407:Tumor Cells, Cultured; D014470:Umbilical Cord / Q000098:blood supply; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
chemical_list: D004167:Diphtheria Toxin; D016228:Endothelial Growth Factors; D000922:Immunotoxins; D008222:Lymphokines; D017978:Receptors, Growth Factor; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D016222:Fibroblast Growth Factor 2; D004247:DNA; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor