title: Unscheduled DNA synthesis induced by N-acetoxy-2-acetylaminofluorene is not sensitive to regulation by ADP-ribosyl transferase.
abstract: We have directly compared in resting human mononuclear leukocytes the DNA repair effects caused by ADP-ribosyl transferase (ADPRT) activity following DNA damage induction by gamma radiation, UV radiation, ethylene oxide (EO) and N-acetoxy-2-acetylaminofluorene (NA-AAF). The presence of inhibitors of ADPRT during the quantitation of unscheduled DNA synthesis (UDS) resulted in about a 2-fold increase of UDS when induced by gamma radiation, UV radiation or EO. The stimulation of UDS by EO, UV- or gamma-radiation in the presence of an ADPRT inhibitor was equally strong whether 1 mM or 10 mM hydroxyurea was used to suppress scheduled DNA synthesis. The level of NA-AAF induced UDS was not affected by inhibitors of ADPRT. In addition, direct estimation of ADPRT activity revealed that at doses giving maximal UDS, NA-AAF damage did not induce a measurable enzymatic activity whereas gamma-radiation, UV radiation and EO all showed a significant dose response increase. We have interpreted our data to mean that NA-AAF induced UDS estimates DNA repair relating mainly to DNA lesions that are recognized with difficulty, and hence, the rate of endonuclease-induced DNA strand break accumulation is not sufficient to allow a stimulation of ADPRT and affect the quantitation of UDS.
mesh_terms: D015073:2-Acetylaminofluorene / Q000031:analogs & derivatives*; D000099:Acetoxyacetylaminofluorene / Q000494:pharmacology*; D004247:DNA / Q000096:biosynthesis* / Q000528:radiation effects; D004260:DNA Repair; D005027:Ethylene Oxide / Q000494:pharmacology; D005720:Gamma Rays; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D009000:Monocytes / Q000378:metabolism; D009713:Nucleotidyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011065:Poly(ADP-ribose) Polymerases
chemical_list: D000099:Acetoxyacetylaminofluorene; D004247:DNA; D015073:2-Acetylaminofluorene; D011065:Poly(ADP-ribose) Polymerases; D009713:Nucleotidyltransferases; D005027:Ethylene Oxide; D006918:Hydroxyurea