Effects of deuterium substitution on the tumorigenicity of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in A/J mice.
Bioassays and DNA-binding studies of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and its analogs with deuterium substitution at the positions alpha to the nitrosamino group ([4,4-D2]NNK and [CD3]NNK) were carried out in A/J mice in order to assess the potential importance of DNA methylation or pyridyloxobutylation in lung tumor induction. The tumorigenic activities of the major NNK metabolite, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and its analog with deuterium at the carbinol carbon ([1-D]NNAL) were also determined. Groups of A/J mice were given single i.p. injections of either 10 or 5 mumol of NNK, [4,4-D2]NNK, [CD3]NNK, NNAL and [1-D]NNAL, and were killed 16 weeks later. Lung tumor multiplicities were as follows in mice treated with 10 mumol: NNK, 7.3 +/- 3.5; [4,4-D2]NNK, 1.4 +/- 1.6; [CD3]NNK, 11.7 +/- 5.4; NNAL, 3.2 +/- 2.0; [1-D]NNAL, 3.2 +/- 2.0. Similar relative tumorigenic activities were observed in mice treated with 5 mumol of these compounds. These results demonstrated that [4,4-D2]NNK was less tumorigenic than NNK and [CD3]NNK was more tumorigenic than NNK. NNAL was less tumorigenic than NNK; substitution of deuterium at the carbinol carbon did not affect its activity. Levels of O6-methylguanine (O6-mG) were measured in pulmonary DNA of A/J mice treated with 10 mumol of NNK, [4,4-D2]NNK or [CD3]NNK, and killed 2 or 24 h later. O6-mG levels were lower in mice treated with [4,4-D2]NNK than in those treated with NNK; no difference in O6-mG levels was observed between those treated with NNK and [CD3]NNK. The results of this study support the hypothesis that O6-mG formation in pulmonary DNA is the key step in lung tumor induction by NNK in A/J mice.
Hecht
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American Health Foundation, Valhalla, NY 10595.
Jordan
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KG
Choi
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CI
Trushin
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D000236:Adenoma / Q000139:chemically induced* / Q000473:pathology; D000818:Animals; D002273:Carcinogens / Q000633:toxicity*; D004247:DNA / Q000187:drug effects / Q000302:isolation & purification; D003903:Deuterium; D005260:Female; D006147:Guanine / Q000031:analogs & derivatives / Q000032:analysis; D008168:Lung / Q000187:drug effects / Q000473:pathology; D008175:Lung Neoplasms / Q000139:chemically induced* / Q000473:pathology; D051379:Mice; D008805:Mice, Inbred A; D009602:Nitrosamines / Q000633:toxicity*; D013329:Structure-Activity Relationship
D002273:Carcinogens; D009602:Nitrosamines; D006147:Guanine; C051577:4-(methylnitrosoamino)-4-(3-pyridyl)-1-butanol; C016583:4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone; D004247:DNA; C008449:O-(6)-methylguanine; D003903:Deuterium