Cell migration is a key process for the defense of pluricellular organisms against pathogens, and it involves a set of surface receptors acting in an ordered fashion to contribute directionality to the movement. Among these receptors are the integrins, which connect the cell cytoskeleton to the extracellular matrix components, thus playing a central role in cell migration. Integrin clustering at focal adhesions drives actin polymerization along the cell leading edge, resulting in polarity of cell movement. Therefore, small integrin-binding proteins such as the snake venom disintegrins that inhibit integrin-mediated cell adhesion are expected to inhibit cell migration. Here we review the current knowledge on disintegrin and disintegrin-like protein effects on cell migration and their potential use as pharmacological tools in anti-inflammatory therapy as well as in inhibition of metastatic invasion.

Vascular endothelial growth factor (VEGF) and αvβ3 integrin are key molecules that actively participate in tumor angiogenesis and metastasis. Some integrin-blocking molecules are currently under clinical trials for cancer and metastasis treatment. However, the mechanism of action of such inhibitors is not completely understood. We have previously demonstrated the anti-angiogenic and anti-metastatic properties of DisBa-01, a recombinant His-tag RGD-disintegrin from Bothrops alternatus snake venom in some experimental models. DisBa-01 blocks αvβ3 integrin binding to vitronectin and inhibits integrin-mediated downstream signaling cascades and cell migration. Here we add some new information on the mechanism of action of DisBa-01 in the tumor microenvironment. DisBa-01 supports the adhesion of fibroblasts and MDA-MB-231 breast cancer cells but it inhibits the adhesion of these cells to type I collagen under flow in high shear conditions, as a simulation of the blood stream. DisBa-01 does not affect the release of VEGF by fibroblasts or breast cancer cells but it strongly decreases the expression of VEGF mRNA and of its receptors, vascular endothelial growth factor receptors 1 and 2 (VEGFR1 and VEGFR2) in endothelial cells. DisBa-01 at nanomolar concentrations also modulates metalloprotease 2 (MMP-2) and 9 (MMP-9) activity, the latter being decreased in fibroblasts and increased in MDA-MB-231 cells. In conclusion, these results demonstrate that αvβ3 integrin inhibitors may induce distinct effects in the cells of the tumor microenvironment, resulting in blockade of angiogenesis by impairing of VEGF signaling and in inhibition of tumor cell motility.

Vascular endothelial growth factor (VEGF) and αvβ3 integrin are key molecules that actively participate in tumor angiogenesis and metastasis. Some integrin-blocking molecules are currently under clinical trials for cancer and metastasis treatment. However, the mechanism of action of such inhibitors is not completely understood and evasive resistance of antiangiogenic therapy has been reported. We have previously demonstrated the anti-angiogenic and anti-metastatic properties of DisBa-01, a recombinant His-tag RGD-disintegrin from Bothrops alternatus snake venom in experimental models. DisBa-01 blocks αvβ3 integrin binding to vitronectin and inhibits integrin mediated downstream signaling cascades and cell migration. Recently, we reported that DisBa-01 strongly decreases the expression of VEGF mRNA and of its receptors, vascular endothelial growth factor receptors 1 and 2 (VEGFR1 and VEGFR2) in endothelial cells. Here, DisBa-01 was submitted to adhesion under flow and transmigration assays, both using different DisBa-01 concentrations and β3-siMDA-MB-231 cells. In the first assay, labeled tumor cells incubated with Disba-01 perfused for 5 minutes through a chamber containing endothelial cells as coat. In the second, labeled tumor cells incubated with DisBa-01 were attracted by complete medium and transmigrated through an endothelial cell coat. Individually, assays were photographed and the cells quantified. Results show that DisBa-01 dose-dependently inhibited adhesion of MDA-MB-231 cells to human endothelial cells under flow conditions, similarly to the effect observed by β3-siMDA-MB-231 cells. In addition, the disintegrin or β3-silencing inhibited the transmigration of tumor cells through endothelial cells in vitro. These results demonstrate that endothelial αvβ3 integrin has a key role in tumor cell adhesion and transmigration through the endothelium under flow conditions. Support: Fapesp (grant no. 1998/14138-2), CNPq, and CAPES (Brazil) Citation Format: Cyntia Freitas Montenegro, Araceli Cristina Durante, Kelli Cristina Micocci, Antonio Carlos Manucci Pereira, Jr., Heloisa Sobreiro Selistre-de-Araujo. A role for endothelial αvβ3 integrin in breast tumor cell migration. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr B44.