title: Activation of caspase-3-dependent and -independent pathways during 7-ketocholesterol- and 7beta-hydroxycholesterol-induced cell death: a morphological and biochemical study.
abstract: On treatment with 7-ketocholesterol (7-keto) or 7beta-hydroxycholesterol (7beta-OH), which are major oxysterols in atherosclerotic plaques, the simultaneous identification of oncotic and apoptotic cells suggests that these compounds activate different metabolic pathways leading to various modes of cell death. With U937, MCF-7 (caspase-3 deficient), MCF-7/c3 cells (stably transfected with caspase-3), we demonstrate that caspase-3 is essential for caspase-9, -7, -8 activation, for Bid degradation mediating mitochondrial cytochrome c release, for cleavage of poly(ADP-ribose) polymerase and inhibitor of the caspase-activated deoxyribonuclease, and, at least in part, for internucleosomal DNA fragmentation. The crucial role of caspase-3 was supported by the use of z-VAD-fmk and z-DEVD-fmk, which abolished apoptosis and the associated events. However, inactivation or lack of caspase-3 did not inhibit 7-keto- and 7beta-OH-induced cell death characterized by staining with propidium iodide, loss of mitochondrial potential. The mitochondrial release of apoptosis-inducing factor and endonuclease G was independent of the caspase-3 status, which conversely played major roles in the morphological aspects of dead cells. We conclude that caspase-3 is essential to trigger 7-keto- and 7beta-OH-induced apoptosis, that these oxysterols simultaneously activate caspase-3-dependent and/or -independent modes of cell death.
authors.affiliation: Inserm U498/IFR 100, CHU/Hôpital du Bocage, Laboratoire de Biochimie Médicale, BP 77908, 21079 Dijon Cedex, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Prunet
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Lemaire-Ewing
authors.forename: Franck
authors.initials: F
authors.lastname: Ménétrier
authors.forename: Dominique
authors.initials: D
authors.lastname: Néel
authors.forename: Gérard
authors.initials: G
authors.lastname: Lizard
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D004789:Enzyme Activation; D005434:Flow Cytometry; D006801:Humans; D006888:Hydroxycholesterols / Q000494:pharmacology*; D007653:Ketocholesterols / Q000494:pharmacology*; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology
chemical_list: D006888:Hydroxycholesterols; D007653:Ketocholesterols; C011724:cholest-5-en-3 beta,7 alpha-diol; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; C003001:7-ketocholesterol