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 GADD45α and 14-3-3σ 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.
Footnotes
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This work was supported by National Institutes of Health Grants R01 ES06460, R01 ES11314, F30 ES013372, T32 ES011564, and P30 ES01247 and by the Kentucky Research Challenge Trust Fund.
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.106.103077.
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ABBREVIATIONS: MAAA, mitotic arrest-associated apoptosis; BrdU, 5-bromo-2′-deoxyuridine; PBS, phosphate-buffered saline; FITC, fluorescein isothiocyanate; DAPI, 4,6-diamidino-2-phenylindole; NSC, nonspecific control; PI, phosphatidylinositol; PARP, poly(ADP-ribose) polymerase; PAGE, polyacrylamide gel electrophoresis; Z, N-benzyloxycarbonyl; FMK, fluoromethyl ketone.
- Received February 17, 2006.
- Accepted April 11, 2006.
- The American Society for Pharmacology and Experimental Therapeutics
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