title: Formation of depurinating N3Adenine and N7Guanine adducts by MCF-10F cells cultured in the presence of 4-hydroxyestradiol.
abstract: Metabolic conversion of endogenous estrogens, estradiol (E2) and estrone (E1), to the catechol estrogens 4-hydroxyE1(E2) [4-OHE1(E2)] has been implicated in the initiation of cancer in rodents and humans. Evidence collected in our laboratories has shown that 4-OHE1(E2) are enzymatically oxidized to E1(E2)-3,4-quinones [E1(E2)-3,4-Q], which have the potential to damage DNA by forming predominantly depurinating adducts, 4-OHE1(E2)-1-N3Ade and 4-OHE1(E2)-1-N7Gua, leading to the accumulation of mutations and probably cell transformation. The human breast epithelial cell line MCF-10F has been transformed by treatment with E2 or 4-OHE2. We have used MCF-10F cells to study the presence of adducts and conjugates after treatment with 4-OHE2. To mimic the intermittent exposure of breast cells to endogenous estrogens, MCF-10F cells were treated with 1 microM 4-OHE2 for a 24-h period at 72, 120, 192 and 240 h postplating. Culture media were collected at each point, extracted by solid-phase extraction and analyzed by HPLC connected with a multichannel electrochemical detector and/or ultraperformance liquid chromatography/tandem mass spectrometry. Media from successive treatments with 4-OHE2 showed the formation of methoxy and cysteine conjugates, and the depurinating adducts 4-OHE1(E2)-1-N3Ade. The amount of 4-OHE1(E2)-1-N3Ade adducts was higher after the third treatment; smaller amounts of the 4-OHE1(E2)-1-N7Gua adducts were detected after the second and third treatments. These results demonstrate that MCF-10F cells oxidize 4-OHE2 to E1(E2)-3,4-Q, which react with DNA to form the depurinating N3Ade and N7Gua adducts. This DNA damage can play an important role in the 4-OHE2-induced mutations and transformation of MCF-10F cells to malignant cells.
authors.affiliation: Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE, USA.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Saeed
authors.forename: Eleanor
authors.initials: E
authors.lastname: Rogan
authors.forename: Sandra V
authors.initials: SV
authors.lastname: Fernandez
authors.forename: Fathima
authors.initials: F
authors.lastname: Sheriff
authors.forename: Jose
authors.initials: J
authors.lastname: Russo
authors.forename: Ercole
authors.initials: E
authors.lastname: Cavalieri
mesh_terms: D000225:Adenine / Q000737:chemistry*; D001940:Breast / Q000166:cytology / Q000378:metabolism; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000187:drug effects / Q000378:metabolism*; D018736:DNA Adducts / Q000378:metabolism*; D004249:DNA Damage; D004958:Estradiol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D002393:Estrogens, Catechol / Q000378:metabolism*; D006147:Guanine / Q000737:chemistry*; D006801:Humans; D015394:Molecular Structure; D052616:Solid Phase Extraction; D053719:Tandem Mass Spectrometry
chemical_list: D018736:DNA Adducts; D002393:Estrogens, Catechol; C500988:estradiol-3,4-quinone; C500989:hexestrol-3',4'-quinone; D004958:Estradiol; D006147:Guanine; D004247:DNA; C014036:4-hydroxyestradiol; D000225:Adenine