VE-Cadherin Disassembly and Cell Contractility in the Endothelium are Necessary for Barrier Disruption Induced by Tumor Cells

Abstract

During metastasis, breakdown of the endothelial barrier is critical for tumor cell extravasation through blood vessel walls and is mediated by a combination of tumor secreted soluble factors and receptor-ligand interactions. However, a complete mechanism governing tumor cell transendothelial migration remains unclear. Here, we investigate the roles of tumor-associated signals in regulating endothelial cell contractility and adherens junction disassembly leading to endothelial barrier breakdown. We show that Src mediates VE-cadherin disassembly in response to metastatic melanoma cells. Through the use of pharmacological inhibitors of cytoskeletal contractility we find that endothelial cell contractility is responsive to interactions with metastatic cancer cells and that reducing endothelial cell contractility abrogates migration of melanoma cells across endothelial monolayers. Furthermore, we find that a combination of tumor secreted soluble factors and receptor-ligand interactions mediate activation of Src within endothelial cells that is necessary for phosphorylation of VE-cadherin and for breakdown of the endothelial barrier. Together, these results provide insight into how tumor cell signals act in concert to modulate cytoskeletal contractility and adherens junctions disassembly during extravasation and may aid in identification of therapeutic targets to block metastasis.

IFN-γ drives inflammatory bowel disease pathogenesis through VE-cadherin–directed vascular barrier disruption

“…The key components of vascular barrier integrity are vessel maturation, as indicated by mural cell coverage of vessels, and endothelial cell-cell interactions (43)(44)(45)(46). To investigate the impact of the vascular IFN-γ response on differential mural cell coverage of vessels in DSS-induced colitis, costaining of CD31 and α-smooth muscle actin (α-SMA) or PDGF receptor-β (PDGFR-β) was performed in resected colon tissues of Ifngr2 ΔEC and control mice.…”

“…Endothelial cell-cell interactions critically depend on adherens junction VE-cadherin. VE-cadherin extracellular domains exposed on the surface of adjacent endothelial cells form homodimeric interactions leading to the tight connection of the cell membranes (43). Loss of VE-cadherin integrity is commonly associated with increased vascular permeability (47).…”

Quantitatively relating brain endothelial cell–cell junction phenotype to global and local barrier properties under varied culture conditions via the Junction Analyzer Program

“…It is important to note that this assay is only measuring the permeability of FITC-avidin and as such, could return different results for the permeability of molecules of different sizes or charges; or for different cell types transmigrating across the barrier. Use of the JAnaP with other local permeability assays for different molecules [63] or live cell imaging for cell transmigration [5,[64][65][66] could, therefore, provide additional insights into the effects of junction phenotypes. This is especially of interest to further study the differences in function between punctate and perpendicular junctions.…”

Fluocell for Ratiometric and High-Throughput Live-Cell Image Visualization and Quantitation

“…The source code, documentation and example data are freely available at our group website and GitHub. The ratiometric image analysis functionalities of Fluocell have been extensively tested by us and other groups [15][16][17][18][19][20][21]. In addition, Fluocell also contains a previously published Diffusion module for image-based FRAP analysis, as well as intensity-based polarity analysis functions which have been used to quantify the spatial distribution of PI3K and Rac1 in polarized cells seeded on micropatterns [22][23][24].…”