title: Stimulation of suicidal erythrocyte death by artesunate.
abstract: BACKGROUND
  The artemisinin derivative artesunate is effective in the treatment of severe malaria and is considered for the treatment of malignancy. Artesunate triggers tumor cell apoptosis, an effect at least in part mediated by mitochondria. Even though lacking mitochondria, erythrocytes may similarly enter suicidal death or eryptosis, which is characterized by cell shrinkage and breakdown of the phospholipid asymmetry of the cell membrane with phosphatidylserine translocation to the erythrocyte surface. Triggers of eryptosis include increase of cytosolic Ca(2+)-activity ([Ca(2+)]i), ceramide formation, and oxidative stress. The present study explored whether artesunate stimulates eryptosis.
  
  
  METHODS
  Phosphatidylserine exposure at the cell surface was estimated from annexin V binding, cell volume from forward scatter, [Ca(2+)]i from Fluo3-fluorescence, ceramide abundance from binding of specific antibodies, and oxidative stress from 2',7'-dichlorodihydrofluorescein-diacetate fluorescence.
  
  
  RESULTS
  A 48 h exposure of human erythrocytes to artesunate significantly increased the percentage of annexin-V-binding cells (≥ 9 µg/ml) without significantly influencing forward scatter. Artesunate significantly increased [Ca(2+)]i. The stimulation of annexin-V-binding by artesunate (15 µg/ml) was significantly blunted but not abolished by removal of extracellular Ca(2+). Artesunate increased the ceramide abundance at the cell surface and the 2',7'-dichlorodihydrofluorescein-diacetate fluorescence.
  
  
  CONCLUSIONS
  Artesunate stimulates phosphatidylserine translocation at the erythrocyte cell membrane, an effect at least partially due to increase of [Ca(2+)]i, stimulation of ceramide formation and generation of oxidative stress.
authors.affiliation: Department of Physiology, University of Tübingen, Tübingen, Germany.
authors.forename: Kousi
authors.initials: K
authors.lastname: Alzoubi
authors.forename: Salvatrice
authors.initials: S
authors.lastname: Calabrò
authors.forename: Rosi
authors.initials: R
authors.lastname: Bissinger
authors.forename: Majed
authors.initials: M
authors.lastname: Abed
authors.forename: Caterina
authors.initials: C
authors.lastname: Faggio
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D037621:Artemisinins / Q000494:pharmacology*; D000077332:Artesunate; D002518:Ceramides / Q000378:metabolism; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000473:pathology; D004912:Erythrocytes / Q000187:drug effects* / Q000473:pathology; D006461:Hemolysis / Q000187:drug effects*; D006801:Humans; D018384:Oxidative Stress / Q000187:drug effects*; D010718:Phosphatidylserines / Q000378:metabolism
chemical_list: D017304:Annexin A5; D037621:Artemisinins; D002518:Ceramides; D010718:Phosphatidylserines; D000077332:Artesunate