In vivo formation of DNA-adducts in mouse skin DNA by tamoxifen.
Tamoxifen (TAM)-induced DNA adduct formation in mouse skin was determined by a nuclease P1-enhanced 32P-postlabelling technique. Topical application of TAM significantly induced a number of DNA-adducts in mouse skin in a dose- and time-dependent manner. When SENCAR mice were topically treated with different doses of TAM for 6 h, total DNA adduct levels in skin were increased by 2.5- (1 mumol TAM), 4.5- (5 mumol TAM) and 4.8-fold (10 mumol TAM), respectively. In addition, at least four novel DNA adducts were observed. Time-course studies showed that TAM-induced DNA adducts reach a peak at 6 h post-treatment. However, the pattern of TAM-induced DNA adducts was different from that induced by DMBA (a potent skin carcinogen). TAM has been found to form DNA-adducts in the liver and kidney of rodents. Our work confirms the genotoxic effects observed by other investigators by showing that TAM also causes DNA-adducts formation in mouse skin. Since TAM is widely used for the treatment of breast cancer and currently for chemo-prevention trials, further studies should be conducted to assess the potential risk of long-term use of TAM in humans.
Cai
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Department of Dermatology, Mount Sinai Medical Center, New York, NY 10029, USA.
Wei
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H
D015127:9,10-Dimethyl-1,2-benzanthracene / Q000633:toxicity; D000818:Animals; D004247:DNA / Q000187:drug effects* / Q000378:metabolism*; D018736:DNA Adducts / Q000096:biosynthesis*; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D005260:Female; D051379:Mice; D018632:Mice, Inbred SENCAR; D012867:Skin / Q000187:drug effects* / Q000378:metabolism*; D013629:Tamoxifen / Q000633:toxicity*
D018736:DNA Adducts; D013629:Tamoxifen; D015127:9,10-Dimethyl-1,2-benzanthracene; D004247:DNA