A comparison of the DNA binding,cytotoxicity and repair synthesis induced in human fibroblasts by reactive derivatives of aromatic amide carcinogens |
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Authors: | RH Heflich RM Hazard L Lommel JD Scribner VM Maher JJ McCormick |
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Institution: | 1. Department of Microbiology, Carcinogenesis Laboratory, Fee Hall, Michigan State University, East Lansing, MI 48824 U.S.A.;2. Department of Biochemistry, Carcinogenesis Laboratory, Fee Hall, Michigan State University, East Lansing, MI 48824 U.S.A.;3. Pacific Northwest Research Foundation, Seattle, WA 98104 U.S.A. |
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Abstract: | The cytotoxicity of three structurally-related direct-acting carcinogens, N-acetoxy-2-acetylaminofluorene, N-acetoxy-2-acetylaminophenanthrene and N-acetoxy-4-acetylaminobiphenyl, was compared in normal cells and in excision repair deficient xeroderma pigmentosum cells (XP12BE). All three proved significantly more cytotoxic to the XP cells than to the normal cells. At equicytoxic levels, substantially more residues were initially bound to the DNA of the normal cells than to the XP cells, suggesting that the former are able to remove a large percentage of the DNA bound residues before these can result in cell death. The ability of these cell strains to remove bound residues from DNA, to incorporate thymidine into parental strands of DNA during repair replication, and to recover from potentially lethal damage if held in the non-replicating, density-inhibited Go state was compared as a function of dose and time. The XP12BE cells proved virtually incapable of excision repair of DNA damage induced by these carcinogens and of recovery. In contrast, normal cells recovered from the potentially lethal effects of these three compounds and did so at a rate comparable to their rate of removal of bound residues and of repair synthesis. In the excision-deficient XP12BE cells, DNA adducts induced by N-acetoxy-2-acetylaminophenanthrene proved 3- to 6-fold more cytotoxic than adducts induced by the other two carcinogens. |
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Keywords: | AABP 4-acetylaminobiphenyl AAF 2-acetylaminofluorene AAPh 2-acetylaminophenanthrene AAS 4-acetylaminostilbene BrdUrd 5-bromo-2-deoxyuridine dThd thymidine MEM Eagle's minimum essential medium NF diploid fibroblast(s) derived from normal individuals PBS phosphate buffered saline (pH 7 2) SSC standard saline citrate (0 15 M NaCl 0 02 M sodium citrate pH 7 5) XP xeroderma pigmentosum |
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