title: Determination of tamoxifen--DNA adducts in leukocytes from breast cancer patients treated with tamoxifen.
abstract: Tamoxifen (TAM), a widely used antiestrogen for breast cancer therapy and chemoprevention, increases the incidence of endometrial cancer in women. The formation of DNA adducts induced by tamoxifen may initiate endometrial cancer. To evaluate the genotoxic risk of TAM, the formation of DNA adducts in leukocytes was examined. Blood samples were collected from 47 breast cancer patients (61.7 +/- 12.5 years) taking TAM (20 mg/day; average duration until sampling, approximately 37 months) and 20 untreated patients (58.2 +/- 12.3 years), and their leukocyte DNA was analyzed by 32P-postlabeling/HPLC analysis. This assay resolves synthetic standards, trans- and cis-diastereoisomers of alpha-(N2-deoxyguanosinyl)tamoxifen 3'-monophosphate (dG3'P-N2-TAM), alpha-(N2-deoxyguanosinyl)-N-desmethyltamoxifen 3'-monophosphate (dG3'P-N2-N-dMeTAM), and alpha-(N2-deoxyguanosinyl)tamoxifen N-oxide 3'-monophosphate', and is capable of determining TAM adducts quantitatively. The detection limit of this assay is 0.6 adducts/10(9) nucleotides. trans-dG3'P-N2-TAM (fr-2; one of the two trans-isomers) was detected in six of 47 breast cancer patients treated with TAM. Among them, trans-dG(3'P-N2-N-dMeTAM (fr-2) was also detected in two patients. The total amounts of TAM-DNA adducts in the positive patients were 2.6 +/- 3.0 adducts/10(9) nucleotides. No adducts were detected in the controls. The presence of TAM-DNA adducts in the leukocyte DNA samples was confirmed using several 32P-postlabeling/HPLC systems.
authors.affiliation: Department of Surgery, School of Medicine, University of Tokushima, Kuramoto-cho 3-18-15, Tokushima 770-8503, Japan. umemoto@clin.med.tokushima-u.ac.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Umemoto
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Monden
authors.forename: Chun-Xing
authors.initials: CX
authors.lastname: Lin
authors.forename: Md
authors.initials: M
authors.lastname: Abdul-Momen
authors.forename: Yuji
authors.initials: Y
authors.lastname: Ueyama
authors.forename: Kansei
authors.initials: K
authors.lastname: Komaki
authors.forename: Y R Santosh
authors.initials: YR
authors.lastname: Laxmi
authors.forename: Shinya
authors.initials: S
authors.lastname: Shibutani
mesh_terms: D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D018736:DNA Adducts / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D004965:Estrogen Antagonists / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D005260:Female; D006801:Humans; D007962:Leukocytes / Q000737:chemistry; D008875:Middle Aged; D013237:Stereoisomerism; D013629:Tamoxifen / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*
chemical_list: D018931:Antineoplastic Agents, Hormonal; D018736:DNA Adducts; D004965:Estrogen Antagonists; D013629:Tamoxifen