Angiogenesis Inhibition by Vascular Endothelial Growth Factor Receptor-2 Blockade Reduces Stromal Matrix Metalloproteinase Expression, Normalizes Stromal Tissue, and Reverts Epithelial Tumor Phenotype in Surface Heterotransplants

Abstract

Inhibition of vascular endothelial growth factor (VEGF) signaling, a key regulator of tumor angiogenesis, through blockade of VEGF receptor (VEGFR)-2 by the monoclonal antibody DC101 inhibits angiogenesis, tumor growth, and invasion. In a surface xenotransplant assay on nude mice using a high-grade malignant squamous cell carcinoma cell line (A-5RT3), we show that DC101 causes vessel regression and normalization as well as stromal maturation resulting in a reversion to a noninvasive tumor phenotype. Vessel regression is followed by down-regulation of expression of both VEGFR-2 and VEGFR-1 on endothelial cells and increased association of A-smooth muscle actin-positive cells with small vessels indicating their normalization, which was further supported by a regular ultrastructure. The phenotypic regression of an invasive carcinoma to a well-demarcated dysplastic squamous epithelium is accentuated by the establishment of a clearly structured epithelial basement membrane and the accumulation of collagen bundles in the stabilized connective tissue. This normalization of the tumorstroma border coincided with down-regulated expression of the stromal matrix metalloproteinases 9 and 13, which supposedly resulted in attenuated turnover of extracellular matrix components permitting their structural organization. Thus, in this mouse model of a human squamous cell carcinoma cell line, blockade of VEGF signaling resulted in the reversion of the epithelial tumor phenotype through stromal normalization, further substantiating the crucial role of stromal microenvironment in regulating the tumor phenotype. (Cancer Res 2005; 65(4): 1294-305)

Platelet-Derived Growth Factor-B Normalizes Micromorphology and Vessel Function in Vascular Endothelial Growth Factor-A-Induced Squamous Cell Carcinomas

“…One potential mechanism behind this invasive growth behavior was suggested by analyzing the expression of stromal and tumor-derived MMPs that were previously identified as hallmarks for malignant, invasive HaCaT-ras xenografts. 42,[67][68][69] We found a similar marked induction of stromal MMP-9 and MMP-13 as well as tumor MMP-1 in transplants of mVEGF-164 transfectant and mVEGF-164 plus hPDGF-B mixed transplants. In contrast, stromal MMP-9 was only marginally expressed in benign HaCaT hPDGF-B transfectant transplants, and stromal MMP-13 and tumor-derived MMP-1 were completely lacking.…”

Granulocyte Colony-Stimulating Factor and Granulocyte-Macrophage Colony-Stimulating Factor Promote Malignant Growth of Cells from Head and Neck Squamous Cell Carcinomas In vivo

“…invasion (48)(49)(50). As tumor angiogenesis is regulated by the disbalanced activity or expression of angiogenic stimulators and inhibitors (51), our data place G-CSF and GM-CSF among the stimulators of tumor angiogenesis in vivo.…”

Vascular Endothelial Growth Factor Stimulates Organ-Specific Host Matrix Metalloproteinase-9 Expression and Ovarian Cancer Invasion

“…Tumor VEGF, however, stimulated invasion, motility, and gelatinase release by murine and human endothelial cells used as a prototype of VEGF-responsive host cells. Besides endothelial cells, other cells can express MMP9, including pericytes, macrophages, or hematopoietic cells (26). Indeed, immunohistochemical analysis revealed that the cells mostly responsible for the production of host MMP9 in the ovaries of 1A9-VS-1 transplanted mice were inflammatory cells morphologically referable to neutrophils.…”