title: Deregulation of NR2E3, an orphan nuclear receptor, by benzo(a)pyrene-induced oxidative stress is associated with histone modification status change of the estrogen receptor gene promoter.
abstract: We previously reported that NR2E3, an orphan nuclear receptor, plays an important role in maintaining the basal expression of estrogen receptor α (ER) and that the NR2E3 level is highly correlated with the relapse-free survival of breast cancer patients. Here, we investigated the role of NR2E3 in benzo(a)pyrene (BaP)-mediated cell injury. BaP treatment reduced NR2E3 homo-dimer formation and expression and subsequently decreased ER expression. The chromatin immunoprecipitation assay results showed that the treatment of MCF-7 breast cancer cells and the mouse liver with BaP released NR2E3 from the ER promoter to transform the transcriptionally active histone modification status into a repressive state. NR2E3 depletion in MCF-7 cells also induced a similar inactive epigenetic status in the ER promoter region, indicating that NR2E3 is an essential epigenetic player that maintains basal ER expression. Interestingly, these negative effects of BaP on the expression levels of NR2E3 and ER were rescued by antioxidant treatment. Collectively, our study provides novel evidence to show that BaP-induced oxidative stress decreases ER expression, in part by regulating NR2E3 function, which modulates the epigenetic status of the ER promoter. NR2E3 is likely an essential epigenetic player that maintains basal ER expression to protect cells from BaP-induced oxidative injury.
authors.affiliation: Department of Environmental Health, University of Cincinnati, College of Medicine, 160 Panzeca way, Cincinnati, OH 45267, USA.
authors.forename: Tilak
authors.initials: T
authors.lastname: Khanal
authors.affiliation: Department of Environmental Health, University of Cincinnati, College of Medicine, 160 Panzeca way, Cincinnati, OH 45267, USA.
authors.forename: Dasom
authors.initials: D
authors.lastname: Kim
authors.affiliation: Department of Environmental Health, University of Cincinnati, College of Medicine, 160 Panzeca way, Cincinnati, OH 45267, USA.
authors.forename: Abby
authors.initials: A
authors.lastname: Johnson
authors.affiliation: Department of Environmental Health, University of Cincinnati, College of Medicine, 160 Panzeca way, Cincinnati, OH 45267, USA.
authors.forename: Divaker
authors.initials: D
authors.lastname: Choubey
authors.affiliation: Department of Environmental Health, University of Cincinnati, College of Medicine, 160 Panzeca way, Cincinnati, OH 45267, USA. Electronic address: kim2ku@ucmail.uc.edu.
authors.forename: Kyounghyun
authors.initials: K
authors.lastname: Kim
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001564:Benzo(a)pyrene / Q000633:toxicity*; D015536:Down-Regulation; D044127:Epigenesis, Genetic; D015972:Gene Expression Regulation, Neoplastic; D056945:Hep G2 Cells; D006657:Histones / Q000235:genetics / Q000378:metabolism; D006801:Humans; D061986:MCF-7 Cells; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D057093:Orphan Nuclear Receptors / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects*; D011401:Promoter Regions, Genetic; D011960:Receptors, Estrogen / Q000235:genetics*
chemical_list: D000975:Antioxidants; D006657:Histones; C485736:Nr2e3 protein, mouse; D057093:Orphan Nuclear Receptors; D011960:Receptors, Estrogen; D001564:Benzo(a)pyrene
keywords: An orphan nuclear receptor; Antioxidant; Epigenetics; Histone demethylase; Polycyclic aromatic hydrocarbon