Glutathione is implied in the control of 7-ketocholesterol-induced apoptosis, which is associated with radical oxygen species production

In a number of experimental systems, inhibition of apoptosis by antioxidant s has led to the production of radical oxygen species (ROS) in certain apop totic forms of cell death. Since antioxidant therapies can reduce vascular dysfunctions in hypercholesterolemic patients who frequently have increased plasma levels of oxysterols constituting potent inducers of apoptosis, we speculate that oxysterol-induced apoptosis could involve oxidative stress. Here, we tested the protective effects of the aminothiols glutathione (GSH) and N-acetylcysteine (NAC), which are two potent antioxidants, on apoptosi s induced by 7-ketocholesterol in U937 cells, and we present evidence indic ating that oxidative processes are involved in 7-ketocholesterol-induced ce ll death. Thus, GSH and NAC prevented phenomenona linked to apoptosis such as reduction of cell growth, increase cellular permeability to propidium io dide, and occurrence of nuclear condensation and/or fragmentation, and they delayed internucleosomal DNA fragmentation. In addition, cell treatment wi th GSH impaired cytochrome c release into the cytosol and degradation of ca spase-8 occurring during cell death. During 7-ketocholesterol-induced apopt osis, we also observed a rapid decrease in cellular GSH content, oxidation of polyunsaturated fatty acids, and a production of ROS by flow cytometry w ith the use of the dye 2',7'-dichlorofluorescin-diacetate; both phenomena w ere inhibited by GSH. Prevention of cell death by GSH and NAC does not seem to be a general rule since these antioxidants impaired etoposide (but not cycloheximide) -induced apoptosis. Taken together, our data demonstrate tha t GSH is implied in the control of 7-ketocholesterol-induced apoptosis asso ciated with the production of ROS.