Regional Effects of an Antivascular Endothelial Growth Factor Receptor Monoclonal Antibody on Receptor Phosphorylation and Apoptosis in Human 253J B-V Bladder Cancer Xenografts

摘要: Vascular endothelial growth factor (VEGF) is a key angiogenic in variety of solid tumors, making it one the most attractive therapeutic targets. VEGF promotes proliferation, survival, and differentiation vascular cells by stimulating autophosphorylation activation receptor-2 (VEGFR-2, fetal liver kinase-1, kinase insert domain-containing receptor). We developed fluorescence-based, quantitative methods to measure total VEGFR-2, VEGFR-2 phosphorylation, apoptosis, microvessel density size within whole tumor cross-sections using laser scanning cytometer. Using these methods, we characterized effects DC101, blocking antibody specific for murine on orthotopic human 253J-BV bladder tumors growing nude mice. Basal levels receptor phosphorylation were heterogeneous, with approximately 50% positive phosphorylated at baseline. DC101 therapy resulted decrease overall 15-fold 8-fold increase cell (CD31-positive) respectively. also decreased density, but mostly affected smaller CD105-negative microvessels located periphery tumor. Intriguingly, anti-VEGFR-2 increased mean vessel an levels. Increases localized core associated expression oxygen-sensitive transcription factor, hypoxia inducible factor-1alpha. These data suggest that VEGFR inhibitors preferentially target discrete populations peripheral blood vessels. Thus, agents single (e.g., VEGFR-2) may not be sufficient completely inhibit angiogenesis.