Formation of Depurinating N3Adenine and N7Guanine Adducts by MCF-10F Cells Cultured in the Presence of 4-hydroxyestradiol

Int J Cancer. 2007 Apr 15;120(8):1821-4. doi: 10.1002/ijc.22399.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenine / chemistry*
  • Breast / cytology
  • Breast / metabolism
  • Cells, Cultured
  • Chromatography, High Pressure Liquid
  • DNA / drug effects
  • DNA / metabolism*
  • DNA Adducts / metabolism*
  • DNA Damage
  • Estradiol / analogs & derivatives*
  • Estradiol / chemistry
  • Estradiol / metabolism
  • Estradiol / pharmacology
  • Estrogens, Catechol / metabolism*
  • Guanine / chemistry*
  • Humans
  • Molecular Structure
  • Solid Phase Extraction
  • Tandem Mass Spectrometry

Substances

  • DNA Adducts
  • Estrogens, Catechol
  • estradiol-3,4-quinone
  • hexestrol-3',4'-quinone
  • Estradiol
  • Guanine
  • DNA
  • 4-hydroxyestradiol
  • Adenine