title: Inhibition of solid tumor growth by gene transfer of VEGF receptor-1 mutants.
abstract: Vascular endothelial growth factor (VEGF) and the high-affinity VEGF receptor Flk-1/KDR (VEGFR-2) are key regulators of tumor angiogenesis. Strategies to block VEGF/VEGFR-2 signaling were successfully used to inhibit experimental tumor growth and indicated that VEGFR-2 is the main signaling VEGF receptor in proliferating tumor endothelium. Here, we investigated the role of the VEGF receptor-1 (VEGFR-1/Flt-1) in the vascularization of 2 different experimental tumors in vivo. VEGFR-1 mutants were generated that lack the intracellular tyrosine kinase domain. Retrovirus-mediated gene transfer of the VEGFR-1 mutants led to a strong reduction of tumor growth and angiogenesis in xenografted C6 glioma and in syngeneic BFS-1 fibrosarcoma. Histological analysis of the inhibited fibrosarcoma revealed reduced vascular density, decreased tumor cell proliferation as well as increased tumor cell apoptosis and the formation of necrosis. The retroviral gene transfer of the full length VEGFR-1 also caused a significant reduction of tumor growth in both models. The inhibitory effects of the VEGFR-1 mutants and the full length VEGFR-1 in BFS-1 fibrosarcoma were mediated through host tumor endothelial cells because the BFS-1 fibrosarcoma cells were not infected by the retrovirus. The formation of heterodimers between VEGFR-2 and full length or truncated VEGFR-1 was observed in vitro and might contribute to the growth inhibitory effect by modulating distinct signal transduction pathways. The results of our study underline the central role of the VEGF/VEGFR-1 signaling system in tumor angiogenesis and demonstrate that VEGFR-1 can serve as a target for anti-angiogenic gene therapy.
authors.affiliation: Department of Molecular Cell Biology, Max Planck Institute for Physiological and Clinical Research, Bad Nauheim, Germany.
authors.forename: Regina
authors.initials: R
authors.lastname: Heidenreich
authors.forename: Marcia
authors.initials: M
authors.lastname: Machein
authors.forename: Anke
authors.initials: A
authors.lastname: Nicolaus
authors.forename: Andreas
authors.initials: A
authors.lastname: Hilbig
authors.forename: Carola
authors.initials: C
authors.lastname: Wild
authors.forename: Matthias
authors.initials: M
authors.lastname: Clauss
authors.forename: Karl H
authors.initials: KH
authors.lastname: Plate
authors.forename: Georg
authors.initials: G
authors.lastname: Breier
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002455:Cell Division / Q000235:genetics*; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D017931:DNA Primers; D005910:Glioma; D006801:Humans; D017403:In Situ Hybridization; D051379:Mice; D016296:Mutagenesis; D009389:Neovascularization, Pathologic / Q000517:prevention & control; D016133:Polymerase Chain Reaction; D014162:Transfection; D014407:Tumor Cells, Cultured; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000235:genetics*
chemical_list: D017931:DNA Primers; D040281:Vascular Endothelial Growth Factor Receptor-1