title: Microtubule alterations and mutations induced by desoxyepothilone B: implications for drug-target interactions.
abstract: Epothilones, like paclitaxel, bind to beta-tubulin and stabilize microtubules. We selected a series of four leukemia sublines that display increasing levels of resistance to the epothilone analog desoxyepothilone B (dEpoB). The dEpoB cells selected in 30-140 nM were approximately 15-fold cross-resistant to paclitaxel, while 300 nM selected cells were 467-fold resistant to this agent. The dEpoB-selected cells are hypersensitive to microtubule destabilizing agents, and express increased levels of class III beta-tubulin and MAP4. A novel class I beta-tubulin mutation, A231T, that affects microtubule stability but does not alter paclitaxel binding, was identified. The 300 nM selected cells acquired a second mutation, Q292E, situated near the M loop of class I beta-tubulin. These cells fail to undergo drug-induced tubulin polymerization due to dramatically reduced drug binding. The dEpoB-resistant leukemia cells provide novel insights into microtubule dynamics and, in particular, drug-target interactions.
authors.affiliation: Children's Cancer Institute Australia for Medical Research, Randwick, New South Wales, 2031, Australia.
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Verrills
authors.forename: Claudia L
authors.initials: CL
authors.lastname: Flemming
authors.forename: Marjorie
authors.initials: M
authors.lastname: Liu
authors.forename: Michael T
authors.initials: MT
authors.lastname: Ivery
authors.forename: Gary S
authors.initials: GS
authors.lastname: Cobon
authors.forename: Murray D
authors.initials: MD
authors.lastname: Norris
authors.forename: Michelle
authors.initials: M
authors.lastname: Haber
authors.forename: Maria
authors.initials: M
authors.lastname: Kavallaris
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D001665:Binding Sites / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D019742:Chemokines, CC / Q000096:biosynthesis / Q000235:genetics; D016503:Drug Delivery Systems; D019008:Drug Resistance, Neoplasm; D004591:Electrophoresis, Polyacrylamide Gel; D034261:Epothilones / Q000494:pharmacology*; D006801:Humans; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000473:pathology; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis / Q000235:genetics; D008870:Microtubules / Q000187:drug effects*; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics / Q000502:physiology*; D017239:Paclitaxel / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014404:Tubulin / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics
chemical_list: D000970:Antineoplastic Agents; D019742:Chemokines, CC; D034261:Epothilones; D008869:Microtubule-Associated Proteins; D014404:Tubulin; C070959:Ccl6 protein, mouse; D017239:Paclitaxel; C114026:desoxyepothilone B