Comparison of hprt and lacI mutant frequency with DNA adduct formation in N-hydroxy-2-acetylaminofluorene-treated Big Blue® rats

• Published in: Environmental and molecular mutagenesis 2001, Vol.37 (3), p.195-202
• Main Authors: Chen, Tao, Mittelstaedt, Roberta A., Aidoo, Anane, Hamilton, L. Patrice, Beland, Frederick A., Casciano, Daniel A., Heflich, Robert H.
• Format: Article
• Language: English
• Subjects: 32P-postlabeling; Animals; Animals, Genetically Modified; Bacterial Proteins - drug effects; Bacterial Proteins - genetics; bone marrow; DNA Adducts; Escherichia coli Proteins; Hydroxyacetylaminofluorene - toxicity; Hypoxanthine Phosphoribosyltransferase - drug effects; Hypoxanthine Phosphoribosyltransferase - genetics; Lac Repressors; liver; Liver - drug effects; Liver - physiology; Lymphocytes - drug effects; Male; Mutation; Organ Specificity; Rats; Rats, Inbred F344; Repressor Proteins - drug effects; Repressor Proteins - genetics; Spleen - cytology; Spleen - drug effects; Spleen - physiology; spleen lymphocytes; transgene
• ISSN: 0893-6692; 1098-2280
• DOI: 10.1002/em.1028

N‐Hydroxy‐2‐acetylaminofluorene (N‐OH‐AAF) is the proximate carcinogenic metabolite of the powerful rat liver carcinogen 2‐acetylaminofluorene. In this study, transgenic Big Blue® rats were used to examine the relationship between in vivo mutagenicity and DNA adduct formation by N‐OH‐AAF in the target liver compared with that in nontarget tissues. Male rats were given one, two, or four doses of 25 mg N‐OH‐AAF/kg body weight by i.p. injection at 4‐day intervals, and groups of treated and control rats were euthanized up to 10 weeks after beginning the dosing. Mutant frequencies were measured in the spleen lymphocyte hprt gene, and lacI mutant frequencies were determined in the liver and spleen lymphocytes. At 6 weeks after beginning the dosing, the hprt mutant frequency in spleen lymphocytes from the four‐dose group was 16.5 × 10−6 compared with 3.2 × 10−6 in control animals. Also at 6 weeks, rats given one, two, or four doses of N‐OH‐AAF had lacI mutant frequencies in the liver of 97.6, 155.6, and 406.8 × 10−6, respectively, compared with a control frequency of 25.7 × 10−6; rats given four doses had lacI mutant frequencies in spleen lymphocytes of 55.8 × 10−6 compared with a control frequency of 20.4 × 10−6. Additional rats were evaluated for DNA adduct formation in the liver, spleen lymphocytes, and bone marrow by 32P‐postlabeling. Adduct analysis was conducted 1 day after one, two, and four treatments with N‐OH‐AAF, 5 days after one treatment, and 9 days after two treatments. N‐(Deoxyguanosin‐8‐yl)‐2‐aminofluorene was the major DNA adduct identified in all the tissues examined. Adduct concentrations increased with total dose to maximum values in samples taken 1 day after two doses, and remained essentially the same after four doses. In samples taken after four doses, adduct levels were 103, 28, and 7 fmol/μg of DNA in liver, spleen lymphocytes, and bone marrow, respectively. The results indicate that the extent of both DNA adduct formation and mutant induction correlates with the organ specificity for N‐OH‐AAF carcinogenesis in the rat. Environ. Mol. Mutagen. 37:195–202, 2001. Published 2001 Wiley‐Liss, Inc.