title: Aphidicolin and 1-beta-D-arabinofuranosylcytosine strongly inhibit transcriptionally active DNA repair in normal human fibroblasts.
abstract: Both aphidicolin and 1-beta-D-arabinofuranosylcytosine (araC) inactivate DNA polymerases alpha, delta and epsilon, and according block long-patch excision repair in mammalian cells. We report here that in normal human fibroblasts both compounds strongly inhibit the repair of damage induced by UV or 4-nitroquinoline-1-oxide in the transcriptionally active c-myc gene, as indicated by the appearance of DNA strand breaks in carcinogen-treated cultures that were subsequently incubated in the presence of either polymerase inhibitor. We further demonstrate that the repair of UV photoproducts in the c-myc gene can be monitored by photolysis (313 nm) of DNA repaired in the presence of bromodeoxyuridine (BrdUrd). In UV-irradiated cultures, the incidence of aphidicolin- or araC-accumulated strand breaks was approximately 70% of that detected by the BrdUrd photolysis assay. Our data therefore implicate a critical role for DNA polymerases alpha, delta and/or epsilon in gene-specific repair in human cells. The techniques described here may prove useful in the study of DNA repair in defined sequences of the human genome following exposure to a diverse array of physical and chemical genotoxic agents.
authors.affiliation: Molecular Oncology Program, Cross Cancer Institute, Edmonton, Alberta, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Mirzayans
authors.forename: K
authors.initials: K
authors.lastname: Dietrich
authors.forename: M C
authors.initials: MC
authors.lastname: Paterson
mesh_terms: D015112:4-Nitroquinoline-1-oxide / Q000633:toxicity; D016590:Aphidicolin / Q000494:pharmacology*; D002460:Cell Line; D003561:Cytarabine / Q000494:pharmacology*; D004260:DNA Repair / Q000187:drug effects* / Q000235:genetics; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D016259:Genes, myc; D006801:Humans; D009153:Mutagens / Q000633:toxicity; D014158:Transcription, Genetic; D014466:Ultraviolet Rays
chemical_list: D009153:Mutagens; D003561:Cytarabine; D016590:Aphidicolin; D015112:4-Nitroquinoline-1-oxide