Efficiency of homocysteine plus copper in inducing apoptosis is inversely proportional to γ‐glutamyl transpeptidase activity

• Published in: The FASEB journal 2001-09, Vol.15 (11), p.1927-1940
• Main Authors: BESSEDE, GINETTE, MIGUET, CAROLE, GAMBERT, PHILIPPE, NEEL, DOMINIQUE, LIZARD, GERARD
• Format: Article
• Language: English
• Subjects: Antineoplastic Agents - pharmacology; Apoptosis; Cell Line; Cell Membrane Permeability; Cell Nucleus - drug effects; Cell Nucleus - metabolism; Cells, Cultured; Copper - metabolism; Cytarabine - pharmacology; Daunorubicin - pharmacology; ECV304 cells; Endothelium, Vascular - cytology; Etoposide - pharmacology; gamma-Glutamyltransferase - metabolism; Hcy; Homocysteine - metabolism; Homocysteine - pharmacology; Humans; HUVECs; Time Factors; Vinblastine - pharmacology; γ‐GT
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fj.00-0848com

ABSTRACT Hyperhomocysteinemia represents an independent risk factor for atherosclerosis, but the mechanisms leading to cellular dysfunctions remain unknown. Using ECV304 cells, we found that homocysteine (Hcy) plus copper (Cu2+) induced cytotoxic effects: loss of cell adhesion, increased permeability to PI, and the occurrence of morphologically apoptotic cells. This form of apoptosis, inhibited by Z‐VAD‐fmk, was associated with a loss of mitochondrial potential, a cytosolic release of cytochrome c, activation of caspase‐3, degradation of poly(ADP‐ribose)polymerase, and inter‐nucleosomal DNA fragmentation. However, the ability of Hcy plus Cu2+ to induce apoptosis decreased when the pretreatment culture time increased. As a positive correlation was found between the length of time of culture before treatment and the enhancement of γ‐glutamyl transpeptidase (γ‐GT) activity, we asked whether γ‐GT was involved in the control of Hcy plus Cu2+‐induced apoptosis. Therefore, ECV304 cells were treated with either acivicin or dexamethasone, inhibiting and stimulating γ‐GT, respectively. In ECV304 cells and human umbilical venous endothelial cells, acivicin favored Hcy plus Cu2+‐induced apoptosis whereas dexa‐methasone counteracted the apoptotic process. As acivi‐cin and dexamethasone were also capable of modulating cell death in ECV304 cells treated with antitumoral drugs, our data emphasize that the involvement of γ‐GT in the control of apoptosis is not restricted to Hcy but also concerns other chemical compounds.