title: p53 suppression of arsenite-induced mitotic catastrophe is mediated by p21CIP1/WAF1.
abstract: Arsenic trioxide, an acute promyelocytic leukemia chemotherapeutic, may be an efficacious treatment for other cancers. Understanding the mechanism as well as genetic and molecular characteristics associated with sensitivity to arsenite-induced cell death is key to providing effective chemotherapeutic usage of arsenite. Arsenite sensitivity correlates with deficient p53 pathways in multiple cell lines. The role of p53 in preventing arsenite-induced mitotic arrest-associated apoptosis (MAAA), a form of mitotic catastrophe, was examined in TR9-7 cells, a model cell line with p53 exogenously regulated in a tetracycline-off expression system. Arsenite activated G1 and G2 cell cycle checkpoints independently of p53, but mitotic catastrophe occurred preferentially in p53- cells. Cyclin B/CDC2(CDK1) stabilization and caspase-3 activation persisted in arsenite-treated p53- cells consistent with MAAA/mitotic catastrophe. N-Benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone, a pan-caspase inhibitor, completely abolished arsenite-induced MAAA/mitotic catastrophe and greatly increased the mitotic index. WEE1 and p21CIP1/WAF1 inhibit cyclin B/CDC2 by CDC2 tyrosine-15 phosphorylation and direct binding, respectively. CDC2-Y15-P was transiently elevated in arsenite-treated p53+ cells but persisted in p53- cells. Arsenite induced p53-S15-P and p21CIP1/WAF1 only in p53+ cells. P21CIP1/WAF1-siRNA-treated p53+ cells were similar to p53- cells in mitotic index and cell cycle protein levels. p53-inducible proteins GADD45alpha and 14-3-3sigma are capable of inhibiting cyclin B/CDC2 but did not play a p53-dependent role in mitotic escape in TR9-7 cells. The data indicate that p53 mediates cyclin B/CDC2 inactivation and mitotic release directly via p21CIP1/WAF1 induction.
authors.affiliation: Department of Pharmacology and Toxicology, University of Louisville, 570 South Preston Street, Suite 221, Louisville, KY 40202, USA.
authors.forename: B Frazier
authors.initials: BF
authors.lastname: Taylor
authors.forename: Samuel C
authors.initials: SC
authors.lastname: McNeely
authors.forename: Heather L
authors.initials: HL
authors.lastname: Miller
authors.forename: Geniece M
authors.initials: GM
authors.lastname: Lehmann
authors.forename: Michael J
authors.initials: MJ
authors.lastname: McCabe
authors.forename: J Christopher
authors.initials: JC
authors.lastname: States
mesh_terms: D018053:Arsenites / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology; D002461:Cell Line, Transformed; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000502:physiology*; D016158:Genes, p53 / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008938:Mitosis / Q000187:drug effects* / Q000502:physiology
chemical_list: D018053:Arsenites; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; C015001:arsenite