The anti-vascular endothelial growth factor receptor-1 monoclonal antibody D16F7 inhibits invasiveness of human glioblastoma and glioblastoma stem cells.

August 10, 2017 By:
  • Atzori MG
  • Tentori L
  • Ruffini F
  • Ceci C
  • Lisi L
  • Bonanno E
  • Scimeca M
  • Eskilsson E
  • Daubon T
  • Miletic H
  • Ricci Vitiani L
  • Pallini R
  • Navarra P
  • Bjerkvig R
  • D'Atri S
  • Lacal PM
  • Graziani G.

BACKGROUND: Glioblastoma (GBM) is a highly migratory, invasive, and angiogenic brain tumor. Like vascular endothelial growth factor-A (VEGF-A), placental growth factor (PlGF) promotes GBM angiogenesis. VEGF-A is a ligand for both VEGF receptor-1 (VEGFR-1) and VEGFR-2, while PlGF interacts exclusively with VEGFR-1. We recently generated the novel anti-VEGFR-1 monoclonal antibody (mAb) D16F7 that diminishes VEGFR-1 homodimerization/activation without affecting VEGF-A and PlGF binding. METHODS: In the present study, we evaluated the expression of VEGFR-1 in human GBM tissue samples (n = 42) by immunohistochemistry, in cell lines (n = 6) and GBM stem cells (GSCs) (n = 18) by qRT-PCR and/or western blot analysis. In VEGFR-1 positive GBM or GSCs we also analyzed the ability of D16F7 to inhibit GBM invasiveness in response to VEGF-A and PlGF. RESULTS: Most of GBM specimens stained positively for VEGFR-1 and all but one GBM cell lines expressed VEGFR-1. On the other hand, in GSCs the expression of the receptor was heterogeneous. D16F7 reduced migration and invasion of VEGFR-1 positive GBM cell lines and patient-derived GSCs in response to VEGF-A and PlGF. Interestingly, this effect was also observed in VEGFR-1 positive GSCs transfected to over-express wild-type EGFR (EGFRwt+) or mutant EGFR (ligand binding domain-deficient EGFRvIII+). Furthermore, D16F7 suppressed intracellular signal transduction in VEGFR-1 over-expressing GBM cells by reducing receptor auto-phosphorylation at tyrosine 1213 and downstream Erk1/2 activation induced by receptor ligands. CONCLUSION: The results from this study suggest that VEGFR-1 is a relevant target for GBM therapy and that D16F7-derived humanized mAbs warrant further investigation.

2017 Aug. J Exp Clin Cancer Res.36(1):106.
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