Original Article

Cancer Chemotherapy and Pharmacology

, Volume 54, Issue 4, pp 315-321

Ascorbate modulation of H2O2 and camptothecin-induced cell death in Jurkat cells

  • Alain-Théophile SanéAffiliated withCentre de recherche sur le vieillissement, Institut Universitaire de Gériatrie de Sherbrooke
  • , André M. CantinAffiliated withUnité de recherche pulmonaire, Centre Hospitalier Universitaire de Sherbrooke
  • , Benoit PaquetteAffiliated withDépartement de médecine nucléaire et radiobiologie, Faculté de Médecine, Université de Sherbrooke
  • , J. Richard WagnerAffiliated withCentre de recherche sur le vieillissement, Institut Universitaire de Gériatrie de SherbrookeDépartement de médecine nucléaire et radiobiologie, Faculté de Médecine, Université de Sherbrooke Email author 

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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 μM) or a single dose of 10 μM H2O2. However, pre-incubation with DHA followed by exposure to H2O2 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.

Keywords

Dehydroascorbate Reactive oxygen species Topoisomerase inhibitors