Reduction of estrogen-induced transformation of mouse mammary epithelial cells by N-acetylcysteine

Divya Venugopal, Muhammad Zahid, Paula C. Mailander, Jane L. Meza, Eleanor G. Rogan, Ercole L. Cavalieri, Dhrubajyoti Chakravarti

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


A growing number of studies indicate that breast cancer initiation is related to abnormal estrogen oxidation to form an excess of estrogen-3,4-quinones, which react with DNA to form depurinating adducts and induce mutations. This mechanism is often called estrogen genotoxicity. 4-Catechol estrogens, precursors of the estrogen-3,4-quinones, were previously shown to account for most of the transforming and tumorigenic activity. We examined whether estrogen-induced transformation can be reduced by inhibiting the oxidation of a 4-catechol estrogen to its quinone. We demonstrate that E6 cells (a normal mouse epithelial cell line) can be transformed by a single treatment with a catechol estrogen or its quinone. The transforming activities of 4-hydroxyestradiol and estradiol-3,4-quinone were comparable. N-Acetylcysteine, a common antioxidant, inhibited the oxidation of 4-hydroxyestradiol to the quinone and consequent formation of DNA adducts. It also drastically reduced estrogen-induced transformation of E6 cells. These results strongly implicate estrogen genotoxicity in mammary cell transformation. Since N-acetylcysteine is well tolerated in clinical studies, it may be a promising candidate for breast cancer prevention.

Original languageEnglish (US)
Pages (from-to)22-30
Number of pages9
JournalJournal of Steroid Biochemistry and Molecular Biology
Issue number1-2
StatePublished - Mar 2008


  • Catechol estrogen quinone
  • Mammary epithelial cells
  • N-acetylcysteine
  • Transformation

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Molecular Medicine
  • Molecular Biology
  • Endocrinology
  • Clinical Biochemistry
  • Cell Biology


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