title: Suppression of high-fidelity double-strand break repair in mammalian chromosomes by pifithrin-alpha, a chemical inhibitor of p53.
abstract: We investigated the effect of pifithrin-alpha (PFTalpha), a chemical inhibitor of p53, on DNA double-strand break (DSB) repair in mammalian chromosomes. Thymidine kinase-deficient mouse fibroblasts were stably transfected with DNA substrates containing one or two recognition sites for yeast endonuclease I-SceI embedded within a herpes simplex virus thymidine kinase gene. Genomic DSBs were induced by introducing an I-SceI expression plasmid into cells in the presence or absence of 20 microM PFTalpha. From cells containing the DNA substrate with a single I-SceI site we recovered low-fidelity nonhomologous end-joining (NHEJ) events in which one or more nucleotides were deleted or inserted at the DSB. From cells containing the substrate with two I-SceI sites we recovered high-fidelity DNA end-joining (precise ligation (PL)) events. We found that treatment of cells with PFTalpha caused a 5-10-fold decrease in recovery of PL but decreased recovery of NHEJ by less than two-fold. Deletion sizes associated with NHEJ were unaffected by treatment with PFTalpha. Our work suggests the possibility that p53 facilitates high-fidelity DSB repair while playing little or no role in mutagenic NHEJ.
authors.affiliation: Department of Biological Sciences, University of South Carolina, 700 Sumter Street, Columbia, SC 29208, USA.
authors.forename: Yunfu
authors.initials: Y
authors.lastname: Lin
authors.forename: Barbara Criscuolo
authors.initials: BC
authors.lastname: Waldman
authors.forename: Alan S
authors.initials: AS
authors.lastname: Waldman
mesh_terms: D000818:Animals; D052160:Benzothiazoles; D002460:Cell Line; D004260:DNA Repair / Q000187:drug effects*; D005347:Fibroblasts; D066298:In Vitro Techniques; D051379:Mice; D013844:Thiazoles / Q000494:pharmacology*; D014050:Toluene / Q000031:analogs & derivatives* / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors*
chemical_list: D052160:Benzothiazoles; D013844:Thiazoles; D016159:Tumor Suppressor Protein p53; D014050:Toluene; C121565:pifithrin