The Integrin Antagonist Cilengitide Activates αVβ3, Disrupts VE-Cadherin Localization at Cell Junctions and Enhances Permeability in Endothelial Cells

Abstract

Cilengitide is a high-affinity cyclic pentapeptdic αV integrin antagonist previously reported to suppress angiogenesis by inducing anoikis of endothelial cells adhering through αVβ3/αVβ5 integrins. Angiogenic endothelial cells express multiple integrins, in particular those of the β1 family, and little is known on the effect of cilengitide on endothelial cells expressing αVβ3 but adhering through β1 integrins. Through morphological, biochemical, pharmacological and functional approaches we investigated the effect of cilengitide on αVβ3-expressing human umbilical vein endothelial cells (HUVEC) cultured on the β1 ligands fibronectin and collagen I. We show that cilengitide activated cell surface αVβ3, stimulated phosphorylation of FAK (Y397 and Y576/577), Src (S418) and VE-cadherin (Y658 and Y731), redistributed αVβ3 at the cell periphery, caused disappearance of VE-cadherin from cellular junctions, increased the permeability of HUVEC monolayers and detached HUVEC adhering on low-density β1 integrin ligands. Pharmacological inhibition of Src kinase activity fully prevented cilengitide-induced phosphorylation of Src, FAK and VE-cadherin, and redistribution of αVβ3 and VE-cadherin and partially prevented increased permeability, but did not prevent HUVEC detachment from low-density matrices. Taken together, these observations reveal a previously unreported effect of cilengitide on endothelial cells namely its ability to elicit signaling events disrupting VE-cadherin localization at cellular contacts and to increase endothelial monolayer permeability. These effects are potentially relevant to the clinical use of cilengitide as anticancer agent.

Cilengitide inhibits progression of experimental breast cancer bone metastases as imaged noninvasively using VCT, MRI and DCE‐MRI in a longitudinal in vivo study

“…Taken together, we conclude that cilengitide triggered a decrease in blood volume (assessed by the amplitude A) due to smaller and partly nonfunctional blood vessels and increased vessel permeability (assessed by the exchange rate constant k ep ) was observed due to the increased number of immature vessels that arose after treatment with cilengitide. Increased vessel permeability as seen in our study was previously reported by Alghisi et al, 46 who reported VE-cadherin delocalization from cell-cell contact sites on cilengitide treatment leading to a loss of cellular contacts and an increase of endothelial monolayer permeability. In bone metastases, this effect might improve local drug delivery to these lesions when combining cilengitide with standard treatments such as bisphosphonates or chemotherapy.…”

Identification of an Endogenously Generated Cryptic Collagen Epitope (XL313) That May Selectively Regulate Angiogenesis by an Integrin Yes-associated Protein (YAP) Mechano-transduction Pathway

“…Although many studies indicate that synthetic RGD-containing peptides inhibit angiogenesis and tumor growth, our findings provide the first evidence that macrophages may generate and release an RGDKGE-containing collagen epitope that may exhibit pro-angiogenic activity. Importantly, previous studies have suggested that certain RGD peptides can activate ␣v␤3 (58,59) and may enhance vascular permeability (45,57), which might lead to release of inflammatory factors, which in turn may contribute to the formation of new blood vessels.…”

“…7, E and F). Activation of Src and p38 MAPK can lead to enhanced actin polymerization and stress fiber formation (43)(44)(45); therefore, we examined the actin cytoskeleton in endothelial cells following binding to the RGD collagen peptides. Interestingly, endothelial cell interactions with the RGD-KGE collagen peptide P-2 resulted in accelerated actin stress fiber formation as a statistically significant increase in the percentage of cells with actin stress fibers were observed in endothelial cells attached to P-2 (RGDKGE) as compared with interactions with P-1 (RGDAPG) peptide (Fig.…”

Confocal Microscopy as Useful Tool for Studying Fibrin-Cell Interactions

“…This would partially explain why Fibrinogen Caracas VIII with normal αC had less interaction with the cells. The contribution of fibrin binding to VE-cadherin to fibrin organization is less clear, since the VE-cadherin contributes to cell-cell and not to cell-extracellular matrix interaction [27].…”