title: The death of ouabain-treated renal epithelial cells: evidence against anoikis occurrence.
abstract: The mechanisms of cell death signaling triggered by cardiotonic steroids are poorly understood. Based on massive detachment of ouabain-treated Madin-Darby canine kidney (MDCK) cells, it may be proposed that the cytotoxic action of these compounds is mediated by anoikis, i.e. a particular mode of death occurring in cells lacking cell-to-extracellular matrix interactions. We tested this hypothesis. Six hour incubation of MDCK cells with ouabain, marinobufagenin or K+-free medium almost completely blocked Na+,K+-ATPase, increased Na (i) + content by approximately 10-fold and suppressed cell attachment to regular-plastic-plates by up to 5-fold. In contrast, the death of attached cells was observed after 24-h incubation with ouabain but not in the presence of marinobufagenin or K+-free medium. Cells treated with ouabain and undergoing anoikis on ultra-low attachment plates exhibited different cell volume behaviour, i.e. swelling and shrinkage, respectively. The pan-caspase inhibitor z-VAD.fmk and the protein kinase C activator PMA rescued MDCK cells from anoikis but did not influence the survival of ouabain-treated cells, whereas medium acidification from pH 7.2 to 6.7 almost completely abolished the cytotoxic action of ouabain, but did not significantly affect anoikis. Our results show that the Na (i) + ,K (i) + -independent mode of MDCK cell death evoked by ouabain is not mediated by anoikis.
authors.affiliation: Research Centre, Centre hospitalier de l'Université de Montréal (CHUM) - Technopôle Angus, 2901 Rachel est, Montreal, Quebec, Canada.
authors.forename: Olga A
authors.initials: OA
authors.lastname: Akimova
authors.forename: Monique
authors.initials: M
authors.lastname: Poirier
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Kotelevtsev
authors.forename: Pavel
authors.initials: P
authors.lastname: Hamet
authors.forename: Sergei N
authors.initials: SN
authors.lastname: Orlov
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D023102:Anoikis / Q000187:drug effects / Q000502:physiology*; D002018:Bufanolides / Q000494:pharmacology; D053148:Caspase 3 / Q000378:metabolism; D061945:Caspase Inhibitors; D016923:Cell Death / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002843:Chromatin / Q000502:physiology; D004285:Dogs; D004789:Enzyme Activation; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000166:cytology* / Q000187:drug effects; D008858:Microscopy, Phase-Contrast; D010042:Ouabain / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D002018:Bufanolides; D061945:Caspase Inhibitors; D002843:Chromatin; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C093896:marinobufagenin; D010042:Ouabain; D011493:Protein Kinase C; D053148:Caspase 3; D000254:Sodium-Potassium-Exchanging ATPase; D013755:Tetradecanoylphorbol Acetate