title: A critical role of glutathione in determining apoptosis sensitivity and resistance in leukemia cells.
abstract: In chemosensitive leukemias and solid tumors, anticancer drugs have been shown to induce apoptosis. Deficiencies in the apoptotic pathways may lead to chemoresistance. Here we report that glutathione (GSH) plays a critical role in activation of apoptosis pathways by CD95 (APO-1/Fas) or anticancer drugs. Upon treatment with anticancer drugs or CD95 triggering, CD95-resistant or Bcl-x(L) overexpressing CEM cells were deficient in activation of apoptosis pathways. CD95-resistant and Bcl-x(L) overexpressing CEM cells exhibited higher intracellular GSH levels in comparison to parental cells. Downregulation of GSH by L-buthionine-(S,R)-sulfoxime (BSO), a specific inhibitor of glutathione synthesis, reversed deficiencies in activation of apoptosis pathways by anticancer drugs or CD95. Interestingly, downregulation of GSH by BSO increased CD95 DISC formation in type I cells. In hybrids of CD95-resistant cells with sensitive cells and hybrids of overexpressing Bcl-x(L) cells with sensitive cells, the phenotype of apoptosis resistance was dominant. Also, in these hybrids, downregulation of GSH reversed CD95- and chemoresistance. We conclude that dominant apoptosis resistance depends, at least in part, on intracellular GSH levels, which may affect apoptosis signaling at different compartments, for example, the death receptor or mitochondria.
authors.affiliation: University Children's Hospital, Prittwitzstr.43, D-89075 Ulm, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Friesen
authors.forename: Y
authors.initials: Y
authors.lastname: Kiess
authors.forename: K-M
authors.initials: KM
authors.lastname: Debatin
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051023:BH3 Interacting Domain Death Agonist Protein; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002459:Cell Fusion; D045744:Cell Line, Tumor; D045304:Cytochromes c / Q000378:metabolism; D053418:Death Domain Receptor Signaling Adaptor Proteins; D015536:Down-Regulation; D004317:Doxorubicin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000502:physiology*; D015870:Gene Expression / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D006822:Hybrid Cells / Q000187:drug effects / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000032:analysis / Q000378:metabolism; D051636:X-Linked Inhibitor of Apoptosis Protein; D051020:bcl-X Protein; D019014:fas Receptor / Q000276:immunology / Q000502:physiology
chemical_list: D000911:Antibodies, Monoclonal; C494811:BCL2L1 protein, human; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D002352:Carrier Proteins; D053418:Death Domain Receptor Signaling Adaptor Proteins; D011506:Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D018124:Receptors, Tumor Necrosis Factor; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D051020:bcl-X Protein; D019014:fas Receptor; D019328:Buthionine Sulfoximine; D004317:Doxorubicin; D045304:Cytochromes c; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D005978:Glutathione