Combretastatin A4 phosphate induces rapid regression of tumor neovessels and growth through interference with vascular endothelial-cadherin signaling
J. Clin. Invest. Loïc Vincent, et al. 115:2992 doi:10.1172/JCI24586 [Go to this article.]

Figure 6
CA4P synergizes with mAb against VE-cadherin (BV13) to block tumor neoangiogenesis. C57BL/6 mice bearing B16 melanoma cells were treated with IgG control, CA4P, anti–VE-cadherin (BV13), or CA4P plus anti–VE-cadherin (BV13) as described in Methods. After an 8-day treatment, tumors were removed and subjected to immunohistochemical analysis. (A) Vessel density determination in B16 melanoma tumors. The importance of intratumoral vascularization was assessed by PECAM-1 immunostaining (red fluorescence). Nuclei were detected by DAPI staining (blue). Note that numerous vessels are seen in the control group, whereas groups of mice treated with CA4P, anti–VE-cadherin (BV13), or combination have markedly fewer neovessels. Representative tumor sections of each group are shown. Magnification: ×20. Scale bar, 100 μm. (B) Quantification of the microvessel density in B16 melanoma tumor sections. The microvessel density is presented as mean number of microvessels per microscopic field ± SEM (*P < 0.05, ^#P < 0.001 compared with the IgG control group; n = 5). (C) CA4P impairs SMC-mediated stabilization of neovessels. The presence of endothelial cells and SMCs was assessed by fluorescence microscopy using PECAM-1 (red) and α-SMA (green) staining, respectively. Note that vessels in the CA4P and CA4P plus anti–VE-cadherin (BV13) groups are not positive for α-SMA, whereas in the absence of CA4P, vessels are surrounded by SMCs. Representative photographs of tumor sections are shown. Magnification: ×100. Scale bar, 10 μm. (D) Quantification of SMC-ensheathed vessels in B16 melanoma tumor sections. The number of SMC-ensheathed vessels is presented as mean number of SMC-ensheathed vessels per microscopic field ± SEM (^#P < 0.001 compared with the IgG control group; n = 5).