Hepatic DNA adduct dosimetry in rats fed tamoxifen: a comparison of methods.
Liver homogenates from rats fed tamoxifen (TAM) in the diet were shared among four different laboratories. TAM-DNA adducts were assayed by high pressure liquid chromatography-electrospray tandem mass spectrometry (HPLC-ES-MS/MS), TAM-DNA chemiluminescence immunoassay (TAM-DNA CIA), and (32)P-postlabeling with either thin layer ((32)P-P-TLC) or liquid chromatography ((32)P-P-HPLC) separation. In the first study, rats were fed a diet containing 500 p.p.m. TAM for 2 months, and the values for measurements of the (E)-alpha-(deoxyguanosin-N(2)-yl)-tamoxifen (dG-N(2)-TAM) adduct in replicate rat livers varied by 3.5-fold when quantified using 'in house' TAM-DNA standards, or other approaches where appropriate. In the second study, rats were fed 0, 50, 250 or 500 p.p.m. TAM for 2 months, and TAM-DNA values were quantified using both 'in house' approaches as well as a newly synthesized [N-methyl-(3)H]TAM-DNA standard that was shared among all the participating groups. In the second study, the total TAM-DNA adduct values varied by 2-fold, while values for the dG-N(2)-TAM varied by 2.5-fold. Ratios of dG-N(2)-TAM:(E)-alpha-(deoxyguanosin-N(2)-yl)-N-desmethyltamoxifen (dG-N(2)-N-desmethyl-TAM) in the second study were approximately 1:1 over the range of doses examined. The study demonstrated a remarkably good agreement for TAM-DNA adduct measurements among the diverse methods employed.
Schild
Laura J
LJ
Carcinogen-DNA Interactions Section, National Cancer Institute, Building 37, Room 4032 NIH, 37 Convent Drive MSC-4255, Bethesda, MD 20892-4255, USA.
Phillips
David H
DH
Osborne
Martin R
MR
Hewer
Alan
A
Beland
Frederick A
FA
Churchwell
Mona I
MI
Brown
Karen
K
Gaskell
Margaret
M
Wright
Elizabeth
E
Poirier
Miriam C
MC
D000818:Animals; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage / Q000737:chemistry / Q000633:toxicity*; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D018736:DNA Adducts / Q000032:analysis* / Q000737:chemistry / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005260:Female; D008099:Liver / Q000737:chemistry* / Q000187:drug effects*; D008163:Luminescent Measurements; D051381:Rats; D011916:Rats, Inbred F344; D021241:Spectrometry, Mass, Electrospray Ionization; D013629:Tamoxifen / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000737:chemistry / Q000633:toxicity*
D018931:Antineoplastic Agents, Hormonal; D018736:DNA Adducts; D013629:Tamoxifen