title: Autocrine VEGFR1 and VEGFR2 signaling promotes survival in human glioblastoma models in vitro and in vivo.
abstract: Although the vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) system has become a prime target for antiangiogenic treatment, its biological role in glioblastoma beyond angiogenesis has remained controversial.
  
  
  
  Using neutralizing antibodies to VEGF or placental growth factor (PlGF) or the tyrosine kinase inhibitor, cediranib, or lentiviral gene silencing, we delineated autocrine signaling in glioma cell lines. The in vivo effects of VEGFR1 and VEGFR2 depletion were evaluated in orthotopic glioma xenograft models.
  
  
  
  VEGFR1 and VEGFR2 modulated glioma cell clonogenicity, viability, and invasiveness in vitro in an autocrine, cell-line-specific manner. VEGFR1 silencing promoted mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling, whereas VEGFR2 silencing resulted in cell-type dependent activation of the protein kinase B (PKB)/AKT and MAPK/ERK pathways. These responses may represent specific escape mechanisms from VEGFR inhibition. The survival of orthotopic glioma-bearing mice was prolonged upon VEGFR1 silencing in the LNT-229, LN-308, and U87MG models and upon VEGFR2 silencing in LN-308 and U87MG. Disruption of VEGFR1 and VEGFR2 signaling was associated with decreased tumor size, increased tumor necrosis, or loss of matrix metalloproteinase 9 (MMP9) immunoreactivity. Neutralizing VEGF and PlGF by specific antibodies was superior to either antibody treatment alone in the VEGFR1-dependent LNT-229 model.
  
  
  
  Differential dependence on autocrine signaling through VEGFR1 and VEGFR2 suggests a need for biomarker-stratified VEGF(R)-based therapeutic approaches to glioblastoma.
authors.affiliation: Laboratory of Molecular Neuro-Oncology, Department of Neurology (E.S., H.S., K.S., M.W.), and Institute of Neuropathology, University Hospital Zurich, Zurich, Switzerland (E.J.R); Roche Innovation Center Penzberg, Roche Pharma Research and Early Development, Nonnenwald 2, Penzberg D-82372, Germany (F.H., K.M.W.).
authors.forename: Emese
authors.initials: E
authors.lastname: Szabo
authors.affiliation: Laboratory of Molecular Neuro-Oncology, Department of Neurology (E.S., H.S., K.S., M.W.), and Institute of Neuropathology, University Hospital Zurich, Zurich, Switzerland (E.J.R); Roche Innovation Center Penzberg, Roche Pharma Research and Early Development, Nonnenwald 2, Penzberg D-82372, Germany (F.H., K.M.W.).
authors.forename: Hannah
authors.initials: H
authors.lastname: Schneider
authors.affiliation: Laboratory of Molecular Neuro-Oncology, Department of Neurology (E.S., H.S., K.S., M.W.), and Institute of Neuropathology, University Hospital Zurich, Zurich, Switzerland (E.J.R); Roche Innovation Center Penzberg, Roche Pharma Research and Early Development, Nonnenwald 2, Penzberg D-82372, Germany (F.H., K.M.W.).
authors.forename: Katharina
authors.initials: K
authors.lastname: Seystahl
authors.affiliation: Laboratory of Molecular Neuro-Oncology, Department of Neurology (E.S., H.S., K.S., M.W.), and Institute of Neuropathology, University Hospital Zurich, Zurich, Switzerland (E.J.R); Roche Innovation Center Penzberg, Roche Pharma Research and Early Development, Nonnenwald 2, Penzberg D-82372, Germany (F.H., K.M.W.).
authors.forename: Elisabeth Jane
authors.initials: EJ
authors.lastname: Rushing
authors.affiliation: Laboratory of Molecular Neuro-Oncology, Department of Neurology (E.S., H.S., K.S., M.W.), and Institute of Neuropathology, University Hospital Zurich, Zurich, Switzerland (E.J.R); Roche Innovation Center Penzberg, Roche Pharma Research and Early Development, Nonnenwald 2, Penzberg D-82372, Germany (F.H., K.M.W.).
authors.forename: Frank
authors.initials: F
authors.lastname: Herting
authors.affiliation: Laboratory of Molecular Neuro-Oncology, Department of Neurology (E.S., H.S., K.S., M.W.), and Institute of Neuropathology, University Hospital Zurich, Zurich, Switzerland (E.J.R); Roche Innovation Center Penzberg, Roche Pharma Research and Early Development, Nonnenwald 2, Penzberg D-82372, Germany (F.H., K.M.W.).
authors.forename: K Michael
authors.initials: KM
authors.lastname: Weidner
authors.affiliation: Laboratory of Molecular Neuro-Oncology, Department of Neurology (E.S., H.S., K.S., M.W.), and Institute of Neuropathology, University Hospital Zurich, Zurich, Switzerland (E.J.R); Roche Innovation Center Penzberg, Roche Pharma Research and Early Development, Nonnenwald 2, Penzberg D-82372, Germany (F.H., K.M.W.) michael.weller@usz.ch.
authors.forename: Michael
authors.initials: M
authors.lastname: Weller
mesh_terms: D000818:Animals; D017209:Apoptosis; D019898:Autocrine Communication; D049109:Cell Proliferation; D048049:Extracellular Signal-Regulated MAP Kinases; D005260:Female; D005909:Glioblastoma / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D008819:Mice, Nude; D009389:Neovascularization, Pathologic; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays
chemical_list: D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2; D048049:Extracellular Signal-Regulated MAP Kinases
keywords: PlGF; VEGF; angiogenesis; glioblastoma; signaling