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Inhibition of the G(2) DNA damage checkpoint and of protein kinases Chk1 and Chk2 by the marine sponge alkaloid debromohymenialdisine

TitleInhibition of the G(2) DNA damage checkpoint and of protein kinases Chk1 and Chk2 by the marine sponge alkaloid debromohymenialdisine
Publication TypeJournal Article
Year of Publication2001
AuthorsCurman, D, Cinel, B, Williams, DE, Rundle, N, Block, WD, Goodarzi, AA, Hutchins, JR, Clarke, PR, Zhou, BB, Lees-Miller, SP, Andersen, RJ, Roberge, M
JournalJournal of Biological Chemistry
Volume276
Pagination17914-17919
Date PublishedMay
Type of ArticleArticle
ISBN Number0021-9258
Keywords14-3-3 BINDING, BHK CELLS, CDC25, CELL-CYCLE CHECKPOINTS, CHROMOSOME, CONDENSATION, DEPENDENT KINASES, H3 PHOSPHORYLATION, INDUCED MITOTIC DELAY, MAMMALIAN-CELLS, PHOSPHATASE, RADIOSENSITIZING AGENT
Abstract

Cells can respond to DNA damage by activating checkpoints that delay cell cycle progression and allow time for DNA repair. Chemical inhibitors of the G(2) phase DNA damage checkpoint may be used as tools to understand better how the checkpoint is regulated and may be used to sensitize cancer cells to DNA-damaging therapies. However, few inhibitors are known. We used a cell-based assay to screen natural extracts for G(2) checkpoint inhibitors and identified debromohymenialdisine (DBH) from a marine sponge. DBH is distinct structurally from previously known G(2) checkpoint inhibitors. It inhibited the G(2) checkpoint with an IC50 of 8 muM and showed moderate cytotoxicity (IC50 = 25 muM) toward MCF-7 cells. DBH inhibited the checkpoint kinases Chk1 (IC50 = 3 muM) and Chk2 (IC50 = 3.5 muM) but not ataxia-telangiectasia mutated (ATM), ATM-Rads-related protein, or DNA-dependent protein kinase in vitro, indicating that it blocks two major branches of the checkpoint pathway downstream of ATM. It did not cause the activation or inhibition of different signal transduction proteins, as determined by mobility shift analysis in Western blots, suggesting that it inhibits a narrow range of protein kinases in vivo.

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