Journal
TOXICOLOGY AND APPLIED PHARMACOLOGY
Volume 270, Issue 2, Pages 139-148Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.taap.2013.03.029
Keywords
Estrogen receptor alpha (ER alpha); Nuclear factor erythroid-2-related factor 2 (NRF2; NFE2L2); Aryl hydrocarbon receptor (AHR); Heme oxygenase I (HMOX1); NADPH dependent oxidoreductase 1 (NQO1); 3,3 '-Diindolylmethane (DIM)
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Funding
- Canadian Breast Cancer Foundation-Ontario (CBCF-ON)
- Canadian Institute of Health Research [MOP 82715]
- CIHR
- Ontario Ministry of Innovation
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Nuclear factor erythroid-2-related factor 2 (NRF2; NFE2L2) plays an important role in mediating cellular protection against reactive oxygen species. NRF2 signaling is positively modulated by the aryl hydrocarbon receptor (AHR) but inhibited by estrogen receptor alpha (ER alpha). In this study we investigated the crosstalk among NRF2, AHR and ERa in MCF-7 breast cancer cells treated with the NRF2 activator sulforaphane (SFN), a dual AHR and ERa activator, 3,3'-diindolylmethane (DIM), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or 17 beta-estradiol (E2).SFN-dependent increases in NADPH-dependent oxidoreductase 1 (NQO1) and heme oxygenase I (HMOX1) mRNA levels were significantly reduced after co-treatment with E2. E2-dependent repression of NQO1 and HMOX1 was associated with increased ERa but reduced p300 recruitment and reduced histone H3 acetylation at both genes. In contrast, DIM + SFN or TCDD + SFN induced NQO1 and HMOX1 mRNA expression to levels higher than SFN alone, which was prevented by RNAi-mediated knockdown of AHR. DIM + SFN but not TCDD + SFN also induced recruitment of ERa to NQO1 and HMOX1. However, the presence of AHR at NQO1 and HMOX1 restored p300 recruitment and histone H3 acetylation, thereby reversing the ER alpha-dependent repression of NRF2. Taken together, our study provides further evidence of functional interplay among NRF2, AHR and ERa signaling pathways through altered p300 recruitment to NRF2-regulated target genes. (C) 2013 Elsevier Inc. All rights reserved.
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