title: Microtubule binding and disruption and induction of premature senescence by disorazole C(1).
abstract: Disorazoles comprise a family of 29 macrocyclic polyketides isolated from the fermentation broth of the myxobacterium Sorangium cellulosum. The major fermentation product, disorazole A(1), was found previously to irreversibly bind to tubulin and to have potent cytotoxic activity against tumor cells, possibly because of its highly electrophilic epoxide moiety. To test this hypothesis, we synthesized the epoxide-free disorazole C(1) and found it retained potent antiproliferative activity against tumor cells, causing prominent G(2)/M phase arrest and inhibition of in vitro tubulin polymerization. Furthermore, disorazole C(1) produced disorganized microtubules at interphase, misaligned chromosomes during mitosis, apoptosis, and premature senescence in the surviving cell populations. Using a tubulin polymerization assay, we found disorazole C(1) inhibited purified bovine tubulin polymerization, with an IC(50) of 11.8 +/- 0.4 microM, and inhibited [3H]vinblastine binding noncompetitively, with a K(i) of 4.5 +/- 0.6 microM. We also found noncompetitive inhibition of [3H]dolastatin 10 binding by disorazole C(1), with a K(i) of 10.6 +/- 1.5 microM, indicating that disorazole C(1) bound tubulin uniquely among known antimitotic agents. Disorazole C(1) could be a valuable chemical probe for studying the process of mitotic spindle disruption and its relationship to premature senescence.
authors.affiliation: Department of Pharmacology and Chemical Biology, University of Pittsburgh Drug Discovery Institute, Biomedical Science Tower 3, Suite 10040, 3401 Fifth Avenue, University of Pittsburgh, Pittsburgh, PA 15260, USA.
authors.forename: Marni Brisson
authors.initials: MB
authors.lastname: Tierno
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Kitchens
authors.forename: Bethany
authors.initials: B
authors.lastname: Petrik
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Graham
authors.forename: Peter
authors.initials: P
authors.lastname: Wipf
authors.forename: Fengfeng L
authors.initials: FL
authors.lastname: Xu
authors.forename: William S
authors.initials: WS
authors.lastname: Saunders
authors.forename: Brianne S
authors.initials: BS
authors.lastname: Raccor
authors.forename: Raghavan
authors.initials: R
authors.lastname: Balachandran
authors.forename: Billy W
authors.initials: BW
authors.lastname: Day
authors.forename: Jane R
authors.initials: JR
authors.lastname: Stout
authors.forename: Claire E
authors.initials: CE
authors.lastname: Walczak
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Ducruet
authors.forename: Celeste E
authors.initials: CE
authors.lastname: Reese
authors.forename: John S
authors.initials: JS
authors.lastname: Lazo
mesh_terms: D019588:Aging, Premature / Q000503:physiopathology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002417:Cattle; D002455:Cell Division / Q000187:drug effects; D016922:Cellular Senescence / Q000187:drug effects*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D016195:G2 Phase / Q000187:drug effects; D006367:HeLa Cells / Q000166:cytology / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D018942:Macrolides; D008870:Microtubules / Q000187:drug effects / Q000502:physiology*; D009231:Myxococcales; D010080:Oxazoles / Q000302:isolation & purification / Q000494:pharmacology*; D014404:Tubulin / Q000378:metabolism; D014747:Vinblastine / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D018942:Macrolides; D010080:Oxazoles; D014404:Tubulin; C436383:disorazole C1; D014747:Vinblastine