In vitro aromatic bioactivation of the weak estrogen E(2)alpha and genesis of DNA adducts.
Specific A-ring hydroxylated metabolites of 17beta-estrogens are known to be endogenous pro-carcinogens, more particularly the 4-hydroxylated forms of estrogens produced by cytochrome P4501B1. In this study, we investigated whether estradiol-17alpha, the main hepatic residue of estradiol-17beta in cattle treated for anabolic purposes with estradiol containing implants, could be significantly metabolized by human cells, and whether its aromatic metabolites could induce the formation of DNA adducts as estradiol-17beta and estrone do. First, using a human kidney adenocarcinoma cell line, which expresses specifically the cytochrome P4501B1, we showed that estradiol-17alpha is bioactivated into a mixture of 2- and 4-catechol estrogens leading to the corresponding methoxyestrogens unambiguously identified by LC-APCI-MS/MS. We then demonstrated that the 2- and 4-hydroxylated derivatives of estradiol-17alpha incubated under oxidative conditions with calf thymus DNA gave stable DNA adducts and abasic sites, respectively. From these results, we can consider that human cells expressing CYP1B1-dependent hydroxylation activities metabolize estradiol-17alpha at the same magnitude as estradiol-17beta and estrone, and that in oxidative conditions, the resulting aromatic metabolites can lead to the formation of both stable and unstable DNA adducts.
Rizzati
Virginie
V
UMR 1089-Xénobiotiques, INRA/ENVT, 180, Chemin de Tournefeuille, BP 3, 31931 Toulouse Cedex 09, France.
Rathahao
Estelle
E
Gamet-Payrastre
Laurence
L
Delous
Georges
G
Jouanin
Isabelle
I
Guéraud
Françoise
F
Paris
Alain
A
D000230:Adenocarcinoma / Q000378:metabolism; D000818:Animals; D002396:Catechols / Q000378:metabolism; D002417:Cattle; D045744:Cell Line, Tumor; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D002855:Chromatography, Thin Layer; D004247:DNA / Q000378:metabolism; D018736:DNA Adducts; D004958:Estradiol / Q000378:metabolism*; D004967:Estrogens / Q000737:chemistry; D002393:Estrogens, Catechol / Q000737:chemistry; D006801:Humans; D006894:Hydroxyestrones / Q000737:chemistry; D006900:Hydroxylation; D066298:In Vitro Techniques; D007680:Kidney Neoplasms / Q000378:metabolism; D013058:Mass Spectrometry; D010100:Oxygen / Q000378:metabolism; D013950:Thymus Gland / Q000378:metabolism; D013997:Time Factors
D002396:Catechols; D018736:DNA Adducts; D004967:Estrogens; D002393:Estrogens, Catechol; D006894:Hydroxyestrones; D004958:Estradiol; D004247:DNA; D010100:Oxygen