Abstract
BackgroundWe analyzed the changes in permeability of endothelial cell layers after photon irradiation, with a focus on the metalloproteases ADAM10 and ADAM17, and on VE-cadherin, components crucial for the integrity of endothelial intercellular junctions, and their roles in the transmigration of cancer cells through endothelial cell monolayers.MethodsPrimary HUVEC were irradiated with 2 or 4 Gy photons at a dose rate of 5 Gy/min. The permeability of an irradiated endothelial monolayer for macromolecules and tumor cells was analyzed in the presence or absence of the ADAM10/17 inhibitors GI254023X and GW280264X. Expression of ADAM10, ADAM17 and VE-Cadherin in endothelial cells was quantified by immunoblotting and qRT. VE-Cadherin was additionally analyzed by immunofluorescence microscopy and ELISA.ResultsIonizing radiation increased the permeability of endothelial monolayers and the transendothelial migration of tumor cells. This was effectively blocked by a selective inhibition (GI254023X) of ADAM10. Irradiation increased both, the expression and activity of ADAM10, which led to increased degradation of VE-cadherin, but also led to higher rates of VE-cadherin internalization. Increased degradation of VE-cadherin was also observed when endothelial monolayers were exposed to tumor-cell conditioned medium, similar to when exposed to recombinant VEGF.ConclusionsOur results suggest a mechanism of irradiation-induced increased permeability and transendothelial migration of tumor cells based on the activation of ADAM10 and the subsequent change of endothelial permeability through the degradation and internalization of VE-cadherin.
Highlights
We analyzed the changes in permeability of endothelial cell layers after photon irradiation, with a focus on the metalloproteases ADAM10 and ADAM17, and on vascular endothelial (VE)-cadherin, components crucial for the integrity of endothelial intercellular junctions, and their roles in the transmigration of cancer cells through endothelial cell monolayers
Endothelial permeability is increased after irradiation The effect of ionizing radiation on the permeability of an endothelial monolayer was investigated and compared with the effects of known permeability-inducing agents such as VEGF [14], Tumor necrosis factor alpha (TNFα) (tumor necrosis factor alpha [15], as well as of 4-Aminophenylmercuric acetate (APMA) (4-aminophenylmercuric acetate) [16], an activator of matrix metalloproteinases
a disintegrin and metalloproteinase (ADAM) inhibitors counteract the radiation-induced increase in endothelial permeability Treating endothelial cell monolayers with the ADAM10 inhibitors GI254023X and GW280264X led to reduced permeability corresponding to approx. 40 and 60%, respectively, of that of controls treated with vehicle (DMSO) alone (100%; Fig. 1c)
Summary
We analyzed the changes in permeability of endothelial cell layers after photon irradiation, with a focus on the metalloproteases ADAM10 and ADAM17, and on VE-cadherin, components crucial for the integrity of endothelial intercellular junctions, and their roles in the transmigration of cancer cells through endothelial cell monolayers. Tumor cells are circulating until they arrive at a (distant) site where they perform extravasation [4, 5] This process depends on complex interactions between cancer cells and the endothelial cell layer lining the vessel and can be divided into three main steps: rolling, adhesion, and transmigration [4, 6]. In this last step, cancer cell have to overcome the vascular endothelial (VE) barrier, which is formed by tight endothelial adherence junctions and VE-cadherin as their major component [7, 8]. Recent studies have shown that VEcadherin is a substrate of the ADAM10 (a disintegrin and metalloproteinase 10) and that its activation leads to an increase in endothelial permeability [13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
