title: Glutathione, cell proliferation, and 1,3-bis-(2-chloroethyl)-1-nitrosourea in K562 leukemia.
abstract: We have pursued our findings of glutathione reductase (GSSG-R) deficiency and disturbed glutathione in cancer patients treated with 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU), by investigating how thiol metabolism, cell proliferation, and the nitrosourea interact in human K562 leukemia. Fasting cells arrested in G greatly increased their reduced glutathione (GSH) in response to growth factors. The rise in thiol began after several hours, peaked before DNA synthesis, and resulted from increased production. BCNU inactivated GSSG-R rapidly, and later retarded, doubled, and greatly prolonged GSH formation before stopping DNA synthesis. Pretreatment unlike post treatment with buthionine-S-R-sulfoximine (BSO) diminished BCNU's ability to block GSSG-R. Enzyme inhibition decreased with falling cellular GSH. In the leukemia system as in vivo, sequential BCNU-induced thiol alterations heralded delayed antiproliferative effects. Drug timing markedly affected both thiol and DNA syntheses. By destroying GSSG-R and delaying the upregulation of thiol synthesis while escalating GSH utilization and requirements, the nitrosourea created a striking and previously unrecognized window of vulnerability for GSH-dependent processes. During this period, altered GSH metabolism could contribute indirectly to BCNU's pleiotropic effects by interfering with DNA alkylation repair, glucose decarboxylation, deoxyribose formation, and possibly by influencing other aspects of proliferation. Acquired GSSG-R deficiency was also an early and sensitive marker for prodrug breakdown and activation.
authors.affiliation: Department of Medicine (Hematology), Rush-Presbyterian-St-Luke's Medical Center, Rush University, Chicago, Illinois 60612.
authors.forename: H
authors.initials: H
authors.lastname: Frischer
authors.forename: E J
authors.initials: EJ
authors.lastname: Kennedy
authors.forename: R
authors.initials: R
authors.lastname: Chigurupati
authors.forename: M
authors.initials: M
authors.lastname: Sivarajan
mesh_terms: D019328:Buthionine Sulfoximine; D002330:Carmustine / Q000494:pharmacology*; D002453:Cell Cycle; D002455:Cell Division / Q000187:drug effects*; D002460:Cell Line; D004260:DNA Repair; D004273:DNA, Neoplasm / Q000096:biosynthesis / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005978:Glutathione / Q000378:metabolism*; D005980:Glutathione Reductase / Q000037:antagonists & inhibitors*; D006801:Humans; D007700:Kinetics; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive; D008717:Methionine Sulfoximine / Q000031:analogs & derivatives / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D004273:DNA, Neoplasm; D008717:Methionine Sulfoximine; D019328:Buthionine Sulfoximine; D005980:Glutathione Reductase; D005978:Glutathione; D002330:Carmustine