Combretastatin A4 phosphate induces rapid regression of tumor neovessels and growth through interference with vascular endothelial-cadherin signaling
Loïc Vincent, … , Chad May, Shahin Rafii
Loïc Vincent, … , Chad May, Shahin Rafii
Published November 1, 2005
Citation Information: J Clin Invest. 2005;115(11):2992-3006. https://doi.org/10.1172/JCI24586.
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Research Article Angiogenesis

Combretastatin A4 phosphate induces rapid regression of tumor neovessels and growth through interference with vascular endothelial-cadherin signaling

Abstract

The molecular and cellular pathways that support the maintenance and stability of tumor neovessels are not well defined. The efficacy of microtubule-disrupting agents, such as combretastatin A4 phosphate (CA4P), in inducing rapid regression of specific subsets of tumor neovessels has opened up new avenues of research to identify factors that support tumor neoangiogenesis. Herein, we show that CA4P selectively targeted endothelial cells, but not smooth muscle cells, and induced regression of unstable nascent tumor neovessels by rapidly disrupting the molecular engagement of the endothelial cell–specific junctional molecule vascular endothelial-cadherin (VE-cadherin) in vitro and in vivo in mice. CA4P increases endothelial cell permeability, while inhibiting endothelial cell migration and capillary tube formation predominantly through disruption of VE-cadherin/β-catenin/Akt signaling pathway, thereby leading to rapid vascular collapse and tumor necrosis. Remarkably, stabilization of VE-cadherin signaling in endothelial cells with adenovirus E4 gene or ensheathment with smooth muscle cells confers resistance to CA4P. CA4P synergizes with low and nontoxic doses of neutralizing mAbs to VE-cadherin by blocking assembly of neovessels, thereby inhibiting tumor growth. These data suggest that the microtubule-targeting agent CA4P selectively induces regression of unstable tumor neovessels, in part through disruption of VE-cadherin signaling. Combined treatment with anti–VE-cadherin agents in conjunction with microtubule-disrupting agents provides a novel synergistic strategy to selectively disrupt assembly and induce regression of nascent tumor neovessels, with minimal toxicity and without affecting normal stabilized vasculature.

Authors

Loïc Vincent, Pouneh Kermani, Lauren M. Young, Joseph Cheng, Fan Zhang, Koji Shido, George Lam, Heidi Bompais-Vincent, Zhenping Zhu, Daniel J. Hicklin, Peter Bohlen, David J. Chaplin, Chad May, Shahin Rafii

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Figure 2

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CA4P impairs capillary tube formation, but has no effect on SMC-stabiliz...
CA4P impairs capillary tube formation, but has no effect on SMC-stabilized tubes, and destabilizes a preestablished vascular network. (A) CA4P inhibits capillary tube formation. HUVECs (3 × 104) were seeded on Matrigel matrix and incubated in the presence of FGF-2 and with 10 nM CA4P. The effect of CA4P on capillary tube formation was observed after a 12-hour incubation under an inverted light microscope. Magnification: ×10 (top panels), ×40 (bottom panels). Scale bar, 10 μm (top panels), 15 μm (bottom panels). (B) Quantification of the CA4P-mediated capillary tube formation inhibition. The quantification was done by measuring the tubule length and counting the number of branch points in 4 different random pictures. Results are expressed as the mean of the tubule length and the mean of the number of branch points ± SEM (**P < 0.01, #P < 0.001 compared with CA4P-untreated cells; n = 4). (C) SMCs protect capillary tube formation against CA4P. HUVECs (3 × 104) stained with red fluorescent cell linker and SMCs (1 × 104) stained with green fluorescent cell linker were seeded together on Matrigel matrix and incubated in presence of FGF-2 and with 10 nM CA4P. The effect of CA4P on capillary tube formation was observed after a 12-hour incubation under an inverted fluorescent microscope. Magnification: ×20. Scale bar, 50 μm. (D) CA4P destabilizes a preestablished vascular network. HUVECs (3 × 104) were seeded on Matrigel matrix and incubated in presence of FGF-2. Once the capillary network formed (after 12 hours), CA4P was added, and the effect of 10 nM CA4P on the disruption of the capillary network was monitored in a time-course manner every 3 hours. There was significant disruption of endothelial cell morphology (arrows). Magnification: ×40. Scale bar, 10 μm.