title: Inhibition of type I histone deacetylase increases resistance of checkpoint-deficient cells to genotoxic agents through mitotic delay.
abstract: Histone deacetylase (HDAC) inhibitors potently inhibit tumor growth and are currently being evaluated for their efficacy as chemosensitizers and radiosensitizers. This efficacy is likely to be limited by the fact that HDAC inhibitors also induce cell cycle arrest. Deletion of the class I HDAC Rpd3 has been shown to specifically suppress the sensitivity of Saccharomyces cerevisiae DNA damage checkpoint mutants to UV and hydroxyurea. We show that in the fission yeast Schizosaccharomyces pombe, inhibition of the homologous class I HDAC specifically suppresses the DNA damage sensitivity of checkpoint mutants. Importantly, the prototype HDAC inhibitor Trichostatin A also suppressed the sensitivity of DNA damage checkpoint but not of DNA repair mutants to UV and HU. TSA suppressed DNA damage activity independently of the mitogen-activated protein kinase-dependent and spindle checkpoint pathways. We show that TSA delays progression into mitosis and propose that this is the main mechanism for suppression of the DNA damage sensitivity of S. pombe checkpoint mutants, partially compensating for the loss of the G(2) checkpoint pathway. Our studies also show that the ability of HDAC inhibitors to suppress DNA damage sensitivity is not species specific. Class I HDACs are the major target of HDAC inhibitors and cancer cells are often defective in checkpoint activation. Effective use of these agents as chemosensitizers and radiosensitizers may require specific treatment schedules that circumvent their inhibition of cell cycle progression.
authors.affiliation: Department of Cell and Molecular Biology, Lundberg Laboratory, University of Gothenburg, S-405 30 Göteborg, Sweden.
authors.forename: John P
authors.initials: JP
authors.lastname: Alao
authors.forename: Jeanette
authors.initials: J
authors.lastname: Olesch
authors.forename: Per
authors.initials: P
authors.lastname: Sunnerhagen
mesh_terms: D000107:Acetylation; D001761:Bleomycin / Q000494:pharmacology; D004249:DNA Damage; D004260:DNA Repair; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005434:Flow Cytometry; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006655:Histone Deacetylases / Q000378:metabolism*; D006877:Hydroxamic Acids / Q000494:pharmacology; D006918:Hydroxyurea / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D008938:Mitosis / Q000187:drug effects*; D009153:Mutagens / Q000494:pharmacology*; D009154:Mutation; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D012568:Schizosaccharomyces / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D009153:Mutagens; D001761:Bleomycin; C012589:trichostatin A; D006655:Histone Deacetylases; D006918:Hydroxyurea