title: In vitro sensitization of erythrocytes to programmed cell death following baicalein treatment.
abstract: The polyphenolic flavonoid Baicalein has been shown to trigger suicidal death or apoptosis of tumor cells and is thus considered for the prevention and treatment of malignancy. Similar to apoptosis of nucleated cells, erythrocytes may enter eryptosis, the suicidal erythrocyte death characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Stimulators of eryptosis include increase of cytosolic Ca2+-activity ([Ca2+]i) and ceramide. The present study explored whether Baicalein stimulates eryptosis. To this end, forward scatter was taken for measurement of cell volume, annexin-V-binding for phosphatidylserine-exposure, Fluo3 fluorescence for [Ca2+]i and fluorescent antibodies for ceramide abundance. As a result, a 48 h exposure of human erythrocytes to Baicalein was followed by significant decrease of forward scatter (≥10 µM), significant increase of the percentage of annexin-V-binding cells (≥25 µM), significant increase of [Ca2+]i (50 µM) and significant increase of ceramide abundance (50 µM). The effect of Baicalein (50 µM) on annexin-V-binding was significantly blunted but not abrogated by removal of extracellular Ca2+. In conclusion, at the concentrations employed, Baicalein stimulates suicidal erythrocyte death or eryptosis, an effect at least in part due to the combined effects of Ca2+ entry and ceramide formation.
authors.affiliation: Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076 Tuebingen, Germany. ro.bissinger@gmx.de.
authors.forename: Rosi
authors.initials: R
authors.lastname: Bissinger
authors.affiliation: Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076 Tuebingen, Germany. malik.abaid@googlemail.com.
authors.forename: Abaid
authors.initials: A
authors.lastname: Malik
authors.affiliation: Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076 Tuebingen, Germany. honisch.s@gmx.de.
authors.forename: Sabina
authors.initials: S
authors.lastname: Honisch
authors.affiliation: Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076 Tuebingen, Germany. jamshedwarsi@yahoo.com.
authors.forename: Jamshed
authors.initials: J
authors.lastname: Warsi
authors.affiliation: Department of Biochemistry, University of Agriculture, 38040 Faisalabad, Pakistan. kashif_cbc@yahoo.com.
authors.forename: Kashif
authors.initials: K
authors.lastname: Jilani
authors.affiliation: Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076 Tuebingen, Germany. florian.lang@uni-tuebingen.de.
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects; D002478:Cells, Cultured; D002518:Ceramides / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism; D044950:Flavanones / Q000494:pharmacology*; D006801:Humans
chemical_list: D002518:Ceramides; D044950:Flavanones; C006680:baicalein; D002118:Calcium