title: Ascorbate modulation of H(2)O(2) and camptothecin-induced cell death in Jurkat cells.
abstract: The effect of ascorbate on cell death was examined in Jurkat cells (human T-cell leukemia) by incubation with dehydroascorbate (DHA), which is rapidly taken up by cells and efficiently reduced to ascorbate. Apoptosis was evaluated by caspase-3 activity in cell extracts and flow cytometry of annexin V-labeled cells. In parallel, necrosis was estimated by the release of lactate dehydrogenase. Minor effects on cell death were observed when Jurkat cells were incubated with either DHA alone (100-1,000 microM) or a single dose of 10 microM H(2)O(2). However, pre-incubation with DHA followed by exposure to H(2)O(2) clearly stimulated both apoptosis and necrosis. In complete contrast, pre-incubation of cells with DHA significantly inhibited apoptosis, but did not affect necrosis, induced by the topoisomerase I inhibitor camptothecin. Our results indicate that intracellular ascorbate can modulate cell death in a manner which depends upon the nature of the apoptotic stimulus, which in turn has critical implications regarding the mechanism and potential application of ascorbate in cancer therapy.
authors.affiliation: Centre de recherche sur le vieillissement, Institut Universitaire de Gériatrie de Sherbrooke, Pavillion d'Youville, 1036 rue Belvédère Sud, J1H 4C4, Sherbrooke, QC, Canada.
authors.forename: Alain-Théophile
authors.initials: AT
authors.lastname: Sané
authors.forename: André M
authors.initials: AM
authors.lastname: Cantin
authors.forename: Benoit
authors.initials: B
authors.lastname: Paquette
authors.forename: J Richard
authors.initials: JR
authors.lastname: Wagner
mesh_terms: D001205:Ascorbic Acid / Q000378:metabolism*; D002166:Camptothecin / Q000494:pharmacology*; D016923:Cell Death; D003683:Dehydroascorbic Acid / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D019169:Jurkat Cells / Q000187:drug effects*; D013997:Time Factors; D059004:Topoisomerase I Inhibitors
chemical_list: D004791:Enzyme Inhibitors; D059004:Topoisomerase I Inhibitors; D006861:Hydrogen Peroxide; D001205:Ascorbic Acid; D002166:Camptothecin; D003683:Dehydroascorbic Acid