Non-random interaction of N-2-acetylaminofluorene and its N-hydroxy metabolite with DNA of rat hepatic parenchymal and non-parenchymal cell nuclei following in vivo administration of carcinogen.
Treatment of rats with the hepatocarcinogen, N-2-acetylaminofluorene (AAF) results in development of malignant tumors derived primarily from hepatic parenchymal cells. Following administration of AAF, or its N-hydroxy derivative, in vivo nuclei from parenchymal cell and non-parenchymal cell populations (NI and NII nuclei populations, respectively) were isolated and treated with the endonuclease DNase I. The binding of carcinogen residues to the DNA of nuclease-accessible vs. nuclease-resistant regions of chromatin was evaluated on the basis of the selectivity of DNase I for transcriptionally active DNA. Under the experimental conditions employed DNase I digested approx. 50-60% of the genome of NI nuclei while only 10-20% of the DNA from non-parenchymal cell nuclei (NII) was susceptible to this enzyme. When the DNA of NI and NII nuclei were nick translated following limited digestion with DNase I, a greater degree of transcriptional activity (nuclease accessibility) was found in parenchymal cell nuclei (NI). Following a single injection of rats with [ring-3H]AAF or its N-hydroxy metabolite (N-[ring-3H]-OH-AAF) (1.8 mumol carcinogen/100 g), adducts were preferentially associated with DNA of DNase I resistant regions of target cell nuclei (NI), while preferentially associated with nuclease-accessible regions of non-target cell nuclei (NII). Damage following a single injection persisted for up to 3 days in DNase I-resistant DNA of NI nuclei, carcinogen adducts were rapidly lost from DNase I-accessible DNA of NII nuclei. These studies stress the importance of investigating specificity of carcinogens for particular regions of the genome of cell subpopulations within the target organ.
D015073:2-Acetylaminofluorene / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism; D004273:DNA, Neoplasm / Q000302:isolation & purification / Q000378:metabolism*; D008099:Liver / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D008113:Liver Neoplasms / Q000139:chemically induced* / Q000235:genetics / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D002843:Chromatin; D004273:DNA, Neoplasm; D015073:2-Acetylaminofluorene