Endogenous oxidative stress prevents telomerase-dependent immortalization of human endothelial cells.
BACKGROUND
With aging, oxidative stress accelerates vascular endothelial cell (EC) telomere shortening-induced senescence, and may promote atherosclerosis in humans. Our aim was to investigate whether an antioxidant treatment combined with telomerase (hTERT) over-expression would prevent senescence of EC isolated from patients with severe atherosclerosis.


METHODS
Cells were isolated from internal mammary arteries (n=11 donors), cultured until senescence with or without N-acetylcystein (NAC) and infected, or not, with a lentivirus over-expressing hTERT.


RESULTS
Compared to control EC, hTERT-NAC cells had increased telomerase activity, longer telomeres and underwent more cell divisions. According to the donor, hTERT-NAC either delayed (n=5) or prevented (n=4) EC senescence, the latter leading to cell immortalization. Lack of cell immortalization by hTERT-NAC was accompanied by an absence of beneficial effect of NAC alone in paired EC. Accordingly, lack of EC immortalization by hTERT-NAC was associated with high endogenous susceptibility to oxidation. In EC where hTERT-NAC did not immortalize EC, p53, p21 and p16 expression increased with senescence, while oxidative-dependent DNA damage associated with senescence was not prevented.


CONCLUSIONS
Our data suggest that irreversible oxidative stress-dependent damages associated with cardiovascular risk factors are responsible for senescence of EC from atherosclerotic patients.
Voghel
Guillaume
G
Department of Surgery, Research Center, Montreal Heart Institute, Université de Montréal, Montréal, Québec, Canada.
Thorin-Trescases
Nathalie
N
Mamarbachi
Aida M
AM
Villeneuve
Louis
L
Mallette
Frédérick A
FA
Ferbeyre
Gerardo
G
Farhat
Nada
N
Perrault
Louis P
LP
Carrier
Michel
M
Thorin
Eric
E
D000111:Acetylcysteine / Q000494:pharmacology; D000368:Aged; D050197:Atherosclerosis / Q000201:enzymology / Q000503:physiopathology*; D002478:Cells, Cultured; D016922:Cellular Senescence; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004249:DNA Damage; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology*; D005260:Female; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress; D012306:Risk; D019098:Telomerase / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016166:Free Radical Scavengers; D016159:Tumor Suppressor Protein p53; D019098:Telomerase; D000111:Acetylcysteine
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