Effects of polybrominated diphenyl ethers on basal and TCDD-induced ethoxyresorufin activity and cytochrome P450-1A1 expression in MCF-7, HepG2, HepG2, and H4IIE cells

A. K. Peters, K. van Londen, Å Bergman, J. Bohonowych, M. S. Denison, M. van den Berg, J. T. Sanderson

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Abstract

Polybrominated, diphenylethers (PBDEs) are used as additive flame-retardants in consumer products to reduce the chances of ignition and burning. Levels of certain PBDE congeners have been increasing, in fish, wildlife, and human tissues during the last decades. Some PBDEs are lipophilic and persistent, resulting in bioaccumulation in the environment. The structural similarity of PBDEs to other polyhalogenated aromatic hydrocarbons such as PCBs, has raised concerns that PBDEs might act as agonists for the aryl hydrocarbon receptor (AhR). To study the possible AhR-mediated effects of the environmentally relevant PBDEs (BDE47, 77, 99, 100, 153, 154, 183, 209), the induction of cytochrome P450-1A1 (CYP1A1) was studied in human breast carcinoma (MCF-7), human hepatocellular carcinoma (HepG2), and rat hepatoma (H4IIE) cells. 7-Ethoxyresorufin-O-deethylase (EROD) was used as a marker for CYP1A1 activity. Cells were exposed for 72 h to various PBDE concentrations (0.01-10 μM). Positive controls were 2,3,7,8-TCDD (0.001-2.5 nM) and PCB·126 (0.01-10 nM). None of these PBDEs was capable of inducing EROD activity; this was confirmed by real time RT-PCR for CYP1A1 mRNA. However, in cells exposed to PBDEs in combination with TCDD, a concentration-dependent decrease in TCDD-induced EROD activity occurred. Co-exposure of BDE153 (10 μM) and a maximally inducing concentration of TCDD (1 nM) reduced EROD activity to 49% of the maximum induction by TCDD alone. All tested PBDEs showed similar effects in each cell line, though quantitative differences were observed. The observed decrease in CYP1A1 activity was not due to PBDE-dependent catalytic inhibition of EROD activity or cytotoxicity, nor were decreased CYP1A1 mRNA levels observed. However, inhibition of luciferase induction in mouse (Hepa) and rat (H4IIE) hepatoma cells containing a stably transfected AhR-responsive luciferase reporter gene, suggests that BDE77 is a weak AhR antagonist or partial agonist.

Original languageEnglish (US)
Pages (from-to)488-496
Number of pages9
JournalToxicological Sciences
Volume82
Issue number2
DOIs
StatePublished - Dec 2004

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Halogenated Diphenyl Ethers
Cytochrome P-450 CYP1A1
Hep G2 Cells
Aryl Hydrocarbon Receptors
Cytochrome P-450 Enzyme System
Hepatocellular Carcinoma
Luciferases
Rats
Flame Retardants
Aromatic Hydrocarbons
Bioaccumulation
Messenger RNA
Consumer products
Polychlorinated Biphenyls
Cytotoxicity
Reporter Genes
Fish
Ignition
Real-Time Polymerase Chain Reaction
Fishes

Keywords

  • Ah receptor
  • Brominated flame retardants
  • Cytochrome P450-1A1
  • EROD
  • H4IIE
  • HepG2
  • MCF-7
  • PBDE

ASJC Scopus subject areas

  • Toxicology

Cite this

Effects of polybrominated diphenyl ethers on basal and TCDD-induced ethoxyresorufin activity and cytochrome P450-1A1 expression in MCF-7, HepG2, HepG2, and H4IIE cells. / Peters, A. K.; van Londen, K.; Bergman, Å; Bohonowych, J.; Denison, M. S.; van den Berg, M.; Sanderson, J. T.

In: Toxicological Sciences, Vol. 82, No. 2, 12.2004, p. 488-496.

Research output: Contribution to journalArticle

Peters, A. K. ; van Londen, K. ; Bergman, Å ; Bohonowych, J. ; Denison, M. S. ; van den Berg, M. ; Sanderson, J. T. / Effects of polybrominated diphenyl ethers on basal and TCDD-induced ethoxyresorufin activity and cytochrome P450-1A1 expression in MCF-7, HepG2, HepG2, and H4IIE cells. In: Toxicological Sciences. 2004 ; Vol. 82, No. 2. pp. 488-496.
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abstract = "Polybrominated, diphenylethers (PBDEs) are used as additive flame-retardants in consumer products to reduce the chances of ignition and burning. Levels of certain PBDE congeners have been increasing, in fish, wildlife, and human tissues during the last decades. Some PBDEs are lipophilic and persistent, resulting in bioaccumulation in the environment. The structural similarity of PBDEs to other polyhalogenated aromatic hydrocarbons such as PCBs, has raised concerns that PBDEs might act as agonists for the aryl hydrocarbon receptor (AhR). To study the possible AhR-mediated effects of the environmentally relevant PBDEs (BDE47, 77, 99, 100, 153, 154, 183, 209), the induction of cytochrome P450-1A1 (CYP1A1) was studied in human breast carcinoma (MCF-7), human hepatocellular carcinoma (HepG2), and rat hepatoma (H4IIE) cells. 7-Ethoxyresorufin-O-deethylase (EROD) was used as a marker for CYP1A1 activity. Cells were exposed for 72 h to various PBDE concentrations (0.01-10 μM). Positive controls were 2,3,7,8-TCDD (0.001-2.5 nM) and PCB·126 (0.01-10 nM). None of these PBDEs was capable of inducing EROD activity; this was confirmed by real time RT-PCR for CYP1A1 mRNA. However, in cells exposed to PBDEs in combination with TCDD, a concentration-dependent decrease in TCDD-induced EROD activity occurred. Co-exposure of BDE153 (10 μM) and a maximally inducing concentration of TCDD (1 nM) reduced EROD activity to 49{\%} of the maximum induction by TCDD alone. All tested PBDEs showed similar effects in each cell line, though quantitative differences were observed. The observed decrease in CYP1A1 activity was not due to PBDE-dependent catalytic inhibition of EROD activity or cytotoxicity, nor were decreased CYP1A1 mRNA levels observed. However, inhibition of luciferase induction in mouse (Hepa) and rat (H4IIE) hepatoma cells containing a stably transfected AhR-responsive luciferase reporter gene, suggests that BDE77 is a weak AhR antagonist or partial agonist.",
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AU - van Londen, K.

AU - Bergman, Å

AU - Bohonowych, J.

AU - Denison, M. S.

AU - van den Berg, M.

AU - Sanderson, J. T.

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