Culp S J, Poirier M C, Beland F A
Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR 72079.
Environ Health Perspect. 1993 Mar;99:273-5. doi: 10.1289/ehp.9399273.
Dietary administration of the hepatocarcinogen 2-acetylaminofluorene (2-AAF) to rats results in the formation of a major hepatic DNA adduct, N-(deoxyguanosin-8-yl)-2-aminofluorene (dG-C8-AF). In liver DNA, dG-C8-AF reaches steady-state conditions after approximately 2 weeks of feeding and is removed in a biphasic manner. In these experiments, we have quantified adduct concentrations in a 370 base-pair repetitive DNA fragment to determine if the adduct levels and kinetics of adduct removal were similar to those found in total genomic DNA. Male F344 rats were fed 0.02% 2-AAF for 28 days and were sacrificed at intermittent times up to 56 days after being returned to the control diet. Hepatic DNA adduct levels were measured by 32P-postlabeling or radioimmunoassay (RIA) in total genomic DNA and in a 370 base-pair fragment obtained by digesting genomic DNA with Hind III. Biphasic removal of dG-C8-AF, which composed about 90% of the total adducts measured, was observed in total genomic DNA, with comparable rate constants being detected by both 32P-postlabeling and RIA. 32P-Postlabeling also showed analogous biphasic removal of dG-C8-AF in the 370 base-pair fragment. A second adduct, 3-(deoxyguanosin-N2-yl)-2-AAF (dG-N2-AAF), which accounted for about 10% of the total adducts measured, showed similar biphasic removal kinetics in the total genomic DNA and the 370 base-pair fragment; however, as compared to dG-C8-AF, little removal of dG-N2-AAF was observed during the slow phase.
给大鼠喂食肝癌致癌物2-乙酰氨基芴（2-AAF）会导致肝脏中形成一种主要的DNA加合物，即N-（脱氧鸟苷-8-基）-2-氨基芴（dG-C8-AF）。在肝脏DNA中，喂食约2周后dG-C8-AF达到稳态，并以双相方式被清除。在这些实验中，我们对一个370个碱基对的重复DNA片段中的加合物浓度进行了定量，以确定加合物水平和加合物清除动力学是否与在全基因组DNA中发现的相似。雄性F344大鼠喂食0.02%的2-AAF 28天，并在恢复对照饮食后长达56天的间隔时间处死。通过32P后标记法或放射免疫测定（RIA）测量全基因组DNA以及用Hind III消化基因组DNA获得的370个碱基对片段中的肝脏DNA加合物水平。在全基因组DNA中观察到dG-C8-AF的双相清除，其约占所测总加合物的90%，通过32P后标记法和RIA检测到的速率常数相当。32P后标记法还显示在370个碱基对片段中dG-C8-AF有类似的双相清除。第二种加合物3-（脱氧鸟苷-N2-基）-2-AAF（dG-N2-AAF）约占所测总加合物的10%，在全基因组DNA和370个碱基对片段中显示出相似的双相清除动力学；然而，与dG-C8-AF相比，在慢相期间几乎没有观察到dG-N2-AAF的清除。
