title: A-204197, a new tubulin-binding agent with antimitotic activity in tumor cell lines resistant to known microtubule inhibitors.
abstract: Drug resistance is a prevalent problem in the treatment of neoplastic disease, and the effectiveness of many clinically useful drugs is limited by the fact that they are substrates for the efflux pump, P-glycoprotein. Because there is a need for new compounds that are effective in treating drug-resistant tumors, we tested A-204197 (4-[4-acetyl-4,5-dihydro-5-(3,4,5-trimethoxyphenyl)-1,3,4-oxadiazol-2-yl]-N,N-dimethylbenzeneamine), a novel oxadiazoline derivative with antiproliferative properties, on cell lines that were either sensitive or resistant to known microtubule inhibitors. Cell lines that were resistant to paclitaxel, vinblastine, or colchicine were equally sensitive to A-204197 (proliferation IC50s ranging from 36 to 48 nM) despite their expression levels of P-glycoprotein. The effect of A-204197 on cell growth was associated with cell cycle arrest in G2-M, increased phosphorylation of select G2-M checkpoint proteins, and apoptosis. In competition-binding assays, A-204197 competed with [3H]-labeled colchicine for binding to tubulin (K(i) = 0.75 microM); however, it did not compete with [3H]-labeled paclitaxel. A-204197 prevented tubulin polymerization in a dose-dependent manner (IC50 = 4.5 microM) in vitro and depolymerized microtubules in a time-dependent manner in cultured cells. These findings indicate A-204197 is a promising new tubulin-binding compound with antimitotic activity that has potential for treating neoplastic diseases with greater efficacy than currently used antimitotic agents.
authors.affiliation: Cancer Research, Pharmaceutical Product Research Division, Abbott Laboratories, Abbott Park, Illinois 60064, USA. stephen.k.tahir@abbott.com
authors.forename: S K
authors.initials: SK
authors.lastname: Tahir
authors.forename: E K
authors.initials: EK
authors.lastname: Han
authors.forename: B
authors.initials: B
authors.lastname: Credo
authors.forename: H S
authors.initials: HS
authors.lastname: Jae
authors.forename: J A
authors.initials: JA
authors.lastname: Pietenpol
authors.forename: C D
authors.initials: CD
authors.lastname: Scatena
authors.forename: J R
authors.initials: JR
authors.lastname: Wu-Wong
authors.forename: D
authors.initials: D
authors.lastname: Frost
authors.forename: H
authors.initials: H
authors.lastname: Sham
authors.forename: S H
authors.initials: SH
authors.lastname: Rosenberg
authors.forename: S C
authors.initials: SC
authors.lastname: Ng
mesh_terms: D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001665:Binding Sites; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000187:drug effects / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D003078:Colchicine / Q000378:metabolism / Q000494:pharmacology; D004347:Drug Interactions; D018432:Drug Resistance, Multiple; D016195:G2 Phase / Q000187:drug effects; D006801:Humans; D008870:Microtubules / Q000187:drug effects* / Q000378:metabolism; D008938:Mitosis / Q000187:drug effects; D010069:Oxadiazoles / Q000378:metabolism / Q000494:pharmacology*; D017239:Paclitaxel / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D014404:Tubulin / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D014747:Vinblastine / Q000494:pharmacology
chemical_list: C431623:4-(4-acetyl-4,5-dihydro-5-(3,4,5-trimethoxyphenyl)-1,3,4-oxadiazol-2-yl)-N,N-dimethylbenzeneamine; D000970:Antineoplastic Agents; D018797:Cell Cycle Proteins; D010069:Oxadiazoles; D019253:Proto-Oncogene Proteins c-bcl-2; D014404:Tubulin; D014747:Vinblastine; D017239:Paclitaxel; D003078:Colchicine