scholarly journals Effect of PTK/ZK on the Angiogenic Switch in Head and Neck Tumors

2008 ◽  
Vol 87 (12) ◽  
pp. 1166-1171 ◽  
Author(s):  
M. Miyazawa ◽  
Z. Dong ◽  
Z. Zhang ◽  
K.G. Neiva ◽  
M.M. Cordeiro ◽  
...  
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Endothelial Cells ◽  
Head And Neck ◽  
Vascular Endothelial ◽  
Head And Neck Tumor ◽  
Angiogenic Switch ◽  
Vegf Signaling ◽  
Neck Tumor ◽  
Neck Tumors ◽  
Endothelial Growth Factor

Transformation of small avascular masses of tumor cells into rapidly progressive cancers is triggered by the angiogenic switch, a process that involves vascular endothelial growth factor (VEGF) signaling. We have shown that VEGF enhances the survival and angiogenic potential of endothelial cells by activating the Bcl-2-CXCL8 signaling axis. The purpose of this study was to evaluate the effect of a small-molecule inhibitor of VEGF receptors (PTK/ZK) on the initial stages of head and neck tumor angiogenesis. In vitro, PTK/ZK blocked head and neck tumor cell (OSCC3 or UM-SCC-17B)-induced Bcl-2 and CXCL8 expression in endothelial cells. Oral administration of PTK/ZK decreased xenograft head and neck tumor microvessel density, and inhibited Bcl-2 and CXCL8 expression in tumor-associated endothelial cells. Analysis of these data demonstrates that PTK/ZK blocks downstream targets of VEGF signaling in endothelial cells, and suggests that PTK/ZK may inhibit the angiogenic switch in head and neck tumors. Abbreviations: HDMEC, human dermal microvascular endothelial cells; VEGF, vascular endothelial growth factor; CXCL8, CXC ligand-8; PTK/ZK, PTK787/ZK222584.

Characterization of the vasculogenic block in the absence of vascular endothelial growth factor-A

Blood ◽  
2000 ◽  
Vol 95 (6) ◽  
pp. 1979-1987 ◽  
Author(s):  
Victoria L. Bautch ◽  
Sambra D. Redick ◽  
Aaron Scalia ◽  
Marco Harmaty ◽  
Peter Carmeliet ◽  
...  
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Endothelial Cells ◽  
Growth Factor ◽  
Embryonic Stem ◽  
Dependent Manner ◽  
Vascular Endothelial ◽  
Vegf Signaling ◽  
Homozygous Mutant ◽  
Endothelial Growth Factor ◽  
Rna Levels

Abstract Vascular endothelial growth factor (VEGF) signaling is required for both differentiation and proliferation of vascular endothelium. Analysis of differentiated embryonic stem cells with one or both VEGF-A alleles deleted showed that both the differentiation and the expansion of endothelial cells are blocked during vasculogenesis. Blood island formation was reduced by half in hemizygous mutant VEGF cultures and by 10-fold in homozygous mutant VEGF cultures. Homozygous mutant cultures could be partially rescued by the addition of exogenous VEGF. RNA levels for the endothelial adhesion receptors ICAM-2 and PECAM were reduced in homozygous mutant cultures, but ICAM-2 RNA levels decreased substantially, whereas PECAM RNA levels remained at hemizygous levels. The quantitative data correlated with the antibody staining patterns because cells that were not organized into vessels expressed PECAM but not ICAM-2. These PECAM+ cell clumps accumulated in mutant cultures as vessel density decreased, suggesting that they were endothelial cell precursors blocked from maturation. A subset of PECAM+ cells in clumps expressed stage-specific embryonic antigen-1 (SSEA-1), and all were ICAM-2(−) and CD34(−), whereas vascular endothelial cells incorporated into vessels were PECAM(+), ICAM-2(+), CD34(+), and SSEA-1(−). Analysis of flk-1 expression indicated that a subset of vascular precursor cells coexpressed PECAM and flk-1. These data suggest that VEGF signaling acts in a dose-dependent manner to affect both a specific differentiation step and the subsequent expansion of endothelial cells.

scholarly journals Lipid Raft Association Stabilizes VEGF Receptor 2 in Endothelial Cells

2021 ◽  
Vol 22 (2) ◽  
pp. 798
Author(s):  
Ibukunoluwapo O. Zabroski ◽  
Matthew A. Nugent
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Endothelial Cells ◽  
Lipid Rafts ◽  
Vegf Receptor ◽  
Vascular Endothelial ◽  
Potential Mechanism ◽  
Lysosomal Degradation ◽  
Extracellular Signal ◽  
The Stability ◽  
Endothelial Growth Factor

The binding of vascular endothelial growth factor A (VEGF) to VEGF receptor-2 (VEGFR-2) stimulates angiogenic signaling. Lipid rafts are cholesterol-dense regions of the plasma membrane that serve as an organizational platform for biomolecules. Although VEGFR2 has been shown to colocalize with lipid rafts to regulate its activation, the effect of lipid rafts on non-activated VEGFR2 has not been explored. Here, we characterized the involvement of lipid rafts in modulating the stability of non-activated VEGFR2 in endothelial cells using raft disrupting agents: methyl-β-cyclodextrin, sphingomyelinase and simvastatin. Disrupting lipid rafts selectively decreased the levels of non-activated VEGFR2 as a result of increased lysosomal degradation. The decreased expression of VEGFR2 translated to reduced VEGF-activation of the extracellular signal-regulated protein kinases (ERK). Overall, our results indicate that lipid rafts stabilize VEGFR2 and its associated signal transduction activities required for angiogenesis. Thus, modulation of lipid rafts may provide a means to regulate the sensitivity of endothelial cells to VEGF stimulation. Indeed, the ability of simvastatin to down regulate VEGFR2 and inhibit VEGF activity suggest a potential mechanism underlying the observation that this drug improves outcomes in the treatment of certain cancers.

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