Proliferation signal inhibitor-induced decrease of vascular endothelial cadherin expression and increase of endothelial permeability in vitro are prevented by an anti-oxidant.
BACKGROUND
Rapamycines, sirolimus (SRL) and everolimus (ERL), are proliferation signal inhibitors (PSIs). PSI therapy often leads to edema. We hypothesized that increased oxidative stress in response to PSIs may modulate the expression of vascular endothelial (VE)-cadherin on endothelial cells (ECs) and, subsequently, vascular permeability, which in turn may be involved in the development of edema.


METHODS
Experiments were performed on human umbilical vein ECs (HUVECs). Oxidative stress was measured by dichlorofluorescein-diacetate. Expression of VE-cadherin was evaluated by immunofluorescent staining and western blot analysis. Endothelial "permeability" was assessed using a transwell model.


RESULTS
SRL and ERL, at concentrations of 1, 10 and 100 nmol/liter, enhanced oxidative stress (SRL: 24 +/- 12%, 29 +/- 9%, 41 +/- 13% [p < 0.05, in all three cases]; ERL: 13 +/- 10%, 27 +/- 2%, 40 +/- 12% [p < 0.05, in the latter two cases], respectively) on HUVECs, which was inhibited by the anti-oxidant, N-acetyl-cysteine (NAC) and, to a lesser extent, by the specific inhibitor of nitric oxide synthase, N-Omega-nitro-L-arginine methylester. By the use of NAC, VE-cadherin expression remained comparable with control, according to both immunocytochemistry and western blot analysis. Permeability was significantly increased by SRL and ERL at 100 nmol/liter (29.5 +/- 6.4% and 33.8 +/- 4.2%, respectively); however, co-treatment with NAC abrogated the increased permeability.


CONCLUSIONS
EC homeostasis, as indicated by VE-cadherin expression, may be damaged by SRL and ERL, but resolved by the anti-oxidant NAC.
Oroszlán
Melinda
M
Department of Cardiology, Heart Transplant Research Laboratory, Swiss Cardiovascular Center Bern, University Hospital Bern (Inselspital), Bern, Switzerland.
Bieri
Michael
M
Ligeti
Nathalie
N
Farkas
Aniko
A
Koestner
Simon C
SC
Meier
Bernhard
B
Mohacsi
Paul J
PJ
D000111:Acetylcysteine / Q000494:pharmacology*; D015820:Cadherins / Q000235:genetics*; D002455:Cell Division / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D000068338:Everolimus; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D018384:Oxidative Stress / Q000187:drug effects*; D010539:Permeability; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D020123:Sirolimus / Q000031:analogs & derivatives* / Q000494:pharmacology*; D014471:Umbilical Veins
D015820:Cadherins; D016166:Free Radical Scavengers; D000068338:Everolimus; D020123:Sirolimus; D000111:Acetylcysteine