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

摘要

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