Peer-Reviewed Journal Details
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Ryan, L,O'Callaghan, YC,O'Brien, NM;
2004
April
Cell Biology and Toxicology
Comparison of the apoptotic processes induced by the oxysterols 7 beta-hydroxycholesterol and cholesterol-5 beta,6 beta-epoxide
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antioxidants apoptosis cholesterol-5 beta,6 beta-epoxide 7 beta-hydroxycholesterol U937 cells LOW-DENSITY-LIPOPROTEIN SMOOTH-MUSCLE-CELLS ALPHA-TOCOPHEROL 7-KETOCHOLESTEROL-INDUCED APOPTOSIS VITAMIN-E ENDOTHELIAL-CELLS OXIDATIVE STRESS HEPG2 CELLS U937 CELLS DEATH
20
313
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Oxysterols have been shown to induce apoptosis in a variety of cell lines. The mechanism of oxysterol-induced apoptosis is mainly known at the post-mitochondrial level. The aim of the present study was to compare the pathway of apoptosis induced by the oxysterols 7beta-hydroxycholesterol (7beta-OH) and cholesterol-5beta,6beta-epoxide (beta-epoxide) in U937 cells. To this end, we employed a range of inhibitors of apoptosis; a broad-spectrum caspase inhibitor, a specific caspase-3 inhibitor and an inhibitor of cytochrome c release and the antioxidants; trolox, ebselen and resveratrol. The three inhibitors of apoptosis prevented cell death induced by 7beta-OH; however, in beta-epoxide-treated cells, the inhibitor of cytochrome c release did not protect against apoptosis. The cellular antioxidant glutathione was depleted in 7beta-OH-treated cells but not in cells incubated with beta-epoxide. Trolox, a water-soluble synthetic analogue of alpha-tocopherol, prevented 7beta-OH-induced apoptosis but did not protect against cell death induced by beta-epoxide. Ebselen and resveratrol did not protect U937 cells against apoptosis induced by either 7beta-OH or beta-epoxide. Our results suggest that differences occur in the pathways of apoptosis induced by 7beta-OH and beta-epoxide in U937 cells.
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