Serum from Methimazole-Treated Patients Induces Activation of Aryl Hydrocarbon Receptor, a Transcription Factor That Binds to Dioxin-Response Elements

Ishikawa, Takahiro; Okinaga, Hiroko; Takahashi, Satoshi; Numakura, Maiko; Mashimo, Yoichi; Yoshimura, Nakayuki; Maeda, Tomomi; Inoue, Daisuke; Okazaki, Ryo; Kinoshita, Makoto; Jameson, J. Larry; Teramoto, Tamio

doi:10.1089/thy.2012.0057

Cited by 5 publications

(6 citation statements)

References 33 publications

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“…1, 7 th , 9 th , 11 th , 13 th and 15 th columns). We suspected that this inhibition by serum might be related to our previous observation that the fold induction of AhR activity by addition of MTH was invariably higher in cells treated in AHS than in cells treated in FBS-containing DMEM [3]. Thus, we tested how MTH induced AhR activity in HepG2-XRE cells incubated in DMEM with or without 10% (v/v) FBS or in AHS, repeating the same experiments at different times (Fig.…”

Section: Resultsmentioning

confidence: 94%

“…1). This observation, along with our previous finding that induction of cellular AhR activity by MTH could be detected more sensitively in AHS than in FBS-supplemented DMEM [3], prompted us to try AHS as a cell culture environment in this study. Nonetheless, theoretically, AHS might not be the best possible environment, given the possibility that the endogenous AhR ligands that should be contained in AHS might interfere with the experiments, even though their physiological concentrations were insufficient for AhR activation as was speculated in the case of bilirubin [1].…”

Section: Discussionmentioning

confidence: 91%

“…HepG2-XRE cells were established as follows. First, an AhR-responsive firefly luciferase reporter gene X 4 -4.27 was constructed by ligating four tandem XREs [the fragment between Kpn I and Xho I sites of the plasmid DRE 4 -GL [3]] into the pGL4.27 vector (Promega, Madison, WI), which carried the firefly luciferase gene and the hygromycin resistance gene. X 4 -4.27 was transfected into HepG2 cells using FuGENE HD (Promega), and stable transfectants were selected using hygromycin B (400 µg/mL).…”

Section: Methodsmentioning

confidence: 99%

“…indole-3-carbinol [2]] and drug metabolites [e.g. 3-methyl-2-thiohydantoin (MTH) [3]]. The activated AhR heterodimerizes with another factor Arnt and binds to xenobiotic response elements (XREs), thereby enhancing transcription of the target genes, such as CYP1A1, CYP1A2, CYP1B1, ALDH3A1, NQO1 and UGT1A1 [4].…”

Section: Introductionmentioning

confidence: 99%

“…We hypothesized that the inconsistency of these two reports on coffee-induced UGT expression was ascribed, at least partly, to the interference from the AhR agonists formed in the culture medium especially after UV irradiation [8], [9]. Thus, instead of the routinely-used culture medium such as Dulbecco’s modified Eagle’s medium (DMEM) containing fetal bovine serum (FBS), we chose to use either Ca 2+ - and Mg 2+ -free phosphate-buffered saline (PBS), which should be devoid of any AhR agonist activity, or adult human serum (AHS), which in our experience had been superior to FBS-supplemented DMEM in sensitively detecting cellular AhR activation [3].…”

Section: Introductionmentioning

confidence: 99%

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Induction of AhR-Mediated Gene Transcription by Coffee

et al. 2014

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BackgroundAryl hydrocarbon receptor (AhR) is classically known to be activated by xenobiotics such as dioxins and polycyclic aromatic hydrocarbons (PAHs). Although it has been reported that PAHs are contained in roasted coffee beans, in general coffee beverages are not considered to be AhR activators. We tested whether exposure to coffee would activate AhR in cultured cells.MethodsHepG2 cells stably expressing an AhR-responsive reporter gene were treated with coffee samples. Also, expression of CYP1A1, an endogenous AhR-responsive gene, was quantitated by RT-PCR and Western blotting in HepG2, Caco-2, and MCF-7 cells, after treatment with coffee. In order to obtain sensitive and reproducible results, all the experiments were performed with the cells placed in either phosphate-buffered saline (PBS) or pure serum, instead of routinely-used culture medium, whose intrinsic AhR-stimulating activity turned out to be so strong as to interfere with the analyses.ResultsAll the coffee samples tested robustly stimulated AhR-mediated transcription in the reporter gene assays. Of note, to what extent coffee and other AhR agonists activated AhR was different, depending on whether the experiments were done in PBS or serum. CYP1A1 mRNA was induced by coffee, in HepG2, Caco-2, and MCF-7 cells placed in either PBS or serum. CYP1A1 protein expression, which was not detected in these cells incubated in PBS, was also increased by coffee in cells placed in serum.ConclusionsBy using culture medium-free experimental settings, we have shown that coffee is a strong AhR activator. Our observation may help elucidate as-yet-unrecognized effects of coffee on human health.

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Section: Resultsmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 91%

Section: Methodsmentioning

confidence: 99%