Cyclooxygenase-2 promoter activation by the aromatic hydrocarbon receptor in breast cancer MCF-7 cells: Repressive effects of conjugated linoleic acid

Stephanie C. Degner, Michael Q. Kemp, Jennifer K. Hockings, Donato Romagnolo

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31 Scopus citations


The role of the aromatic hydrocarbon receptor (AhR) in transcriptional regulation of the human cyclooxygenase-2 (COX-2) gene remains elusive. We report that the AhR-ligands benzo[a]pyrene and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced transcription activity of COX-2 in breast cancer MCF-7 cells. The TCDD-dependent activation of the COX-2 promoter was abrogated by mutation of 2 xenobiotic response elements (XREs) = CGTG). We found that TCDD stimulated the binding of the AhR to COX-2 and cytochrome P4501A1 (CYP1A1) oligonucleotides containing consensus XREs. Conversely, the cotreatment with TCDD plus a mixture of conjugated linoleic acid (CLA) or selected CLA isomers prevented (CLAmix = t10,c12-CLA>c9,t11-CLA) the induction of transcription from the COX-2 promoter. The TCDD-induced binding of the AhR to COX-2 and CYP1A1 oligonucleotides was repressed by cotreatment with CLA (t10,c12-CLA>c9,t11- CLA), and the AhR antagonists, 3-methoxy-4-naphthoflavone, and resveratrol. We conclude that the AhR may be a suitable target for prophylactic strategies that target COX-2 expression.

Original languageEnglish (US)
Pages (from-to)248-257
Number of pages10
JournalNutrition and Cancer
Issue number2
Publication statusPublished - 2007


ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Oncology
  • Food Science

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