3′-Methoxy-4′-nitroflavone, a reported aryl hydrocarbon receptor antagonist, enhances Cyp1a1 transcription by a dioxin responsive element-dependent mechanism☆
Section snippets
Chemicals
Seven flavonoid compounds, 3′,4′-dimethoxyflavone (3′,4′MF), 3′-acetamideflavone (3′AAF), 3′,5′-dimethoxyflavone (3′,5′MF), 4′-nitro-7,8-benzoflavone (4′N7,8BF), 3′-dimethylaminoflavone (3′DMAF), 7,8-benzoflavone (ANF), and 3′-methoxy-4′-nitroflavone (3′M4′NF), were synthesized by the procedure of Cunningham et al. (1992) as previously described [21]. TCDD was purchased from Cambridge Isotopes (Cambridge, MA); benzo(a)pyrene (BaP), actinomycin D, and cycloheximide were from Sigma Chemicals (St.
Differential activity of 3′M4′NF on Cyp1a1 and p2DLuc genes
Initial experiments were designed to investigate if a stably transfected luciferase reporter gene has responsiveness that is similar to an endogenous gene following AhR activation by structurally diverse ligands. The effects of 3′M4′NF and TCDD on expression of CYP1A1 and reporter luciferase proteins were examined in Hepa.2DLuc.3A4 cells by Western blot analysis (Fig. 1A). As expected, TCDD produced a concentration-dependent increase in both the endogenous and reporter proteins. Unlike TCDD, 3′
Discussion
This study investigated AhR-mediated endogenous Cyp1a1 and luciferase reporter gene expression within the same cell system in response to TCDD and 3′M4′NF. Taken together, data on mRNA, protein, and luciferase enzymatic activity indicated that TCDD and 3′M4′NF played different roles in regulating these genes. While TCDD enhanced expression of both reporter and endogenous genes, 3′M4′NF acted as an agonist for Cyp1a1, but an apparent antagonist for luciferase.
Immunoprecipitation and
Acknowledgements
We thank Dr. J.P. Whitlock, Jr. (Stanford University) for the kind gift of Cyp1a1 promoter deletion constructs D16, D17, D8, and individual DRE-driven CAT reporter constructs. We thank Dr. A.S. Kende (University of Rochester) for the synthesis of substituted flavones. We also thank the members of our laboratory for the critical review of the manuscript.
References (36)
- et al.
J. Biol. Chem.
(1997) - et al.
J. Biol. Chem.
(1989) - et al.
J. Biol. Chem.
(1996) - et al.
Eur. J. Pharmacol.
(1992) - et al.
Fundam. Appl. Toxicol.
(1996) - et al.
Toxicol. Appl. Pharmacol.
(1996) - et al.
Fundam. Appl. Toxicol.
(1996) - et al.
Eur. J. Pharmacol.
(1995) - et al.
Biochem. Pharmacol.
(1996) - et al.
Biochem. Pharmacol.
(1995)
Biochem. Pharmacol.
Biochem. Pharmacol.
Arch. Biochem. Biophys.
Arch. Biochem. Biophys.
Arch. Biochem. Biophys.
Mol. Pharmacol.
J. Biol. Chem.
Life Sci.
Cited by (31)
An overview of aryl hydrocarbon receptor ligands in the Last two decades (2002–2022): A medicinal chemistry perspective
2022, European Journal of Medicinal ChemistryCitation Excerpt :The literatures show that various flavones including flavonoids, flavonols, and flavanones have emerged as SAhRMs and exhibited momentous therapeutic potential in AhR-dependent regulation of pro/anti-apoptosis, inflammatory responses, cell cycle, and the expression of active enzymes with cardioprotective or body-defense effects (Fig. 16) [27,160]. Moreover, 3′4-dimethoxy-α-naphthoflavone (XI-5), α-naphthoflavone (XI-7) and 3′-methoxy-4′-nitroflavone (XI-8) were initially characterized as AhR antagonists, but subsequent investigations have shown that they not only have agonist activity, but also antagonist activity [237,238]. Depending on its concentration as well as promoter context of particular genes, the ability of 3′-methoxy-4′-nitroflavone to act as an AhR antagonist or agonist appear different for various genes [238].
Metformin attenuates V-domain Ig suppressor of T-cell activation through the aryl hydrocarbon receptor pathway in Melanoma: In Vivo and In Vitro Studies
2022, Saudi Pharmaceutical JournalCitation Excerpt :In the second approach, we tested the pharmacological modulation of the AHR pathway level using Western blot. We used alpha-naphthoflavone (αNF) as an AHR stimulant or inhibitor, depending on the concentration (Blank et al., 1987, Santostefano et al., 1993, Lu et al., 1995, Zhou and Gasiewicz 2003). Two concentrations of αNF were treated CHL-1 for 24 h, and results showed that 5 µM significantly decreased VISTA, AHR, and CYP1A1 protein levels by up to 33, 30, and 24%, as compared to untreated cells.
Aryl hydrocarbon receptor-dependent cell cycle arrest in isolated mouse oval cells
2013, Toxicology LettersHarmaline and harmalol inhibit the carcinogen-activating enzyme CYP1A1 via transcriptional and posttranslational mechanisms
2012, Food and Chemical ToxicologyTranscriptional and posttranslational inhibition of dioxin-mediated induction of CYP1A1 by harmine and harmol
2012, Toxicology LettersCitation Excerpt :It has been previously reported that the genotoxicity associated with benzo(a)pyrene in mice was inhibited by AhR antagonists such as 3′-methoxy-4′-nitroflavone and resveratrol (Dertinger et al., 2001; Revel et al., 2003). However, several AhR antagonists lack specificity and can act as partial agonists, therefore, the search for new AhR antagonist is still in progress (Puppala et al., 2008; Signorelli and Ghidoni, 2005; Zhou and Gasiewicz, 2003). Harmine is metabolized in the liver and extrahepatic tissues to its main metabolite, harmol, by the cytochrome P450s, mainly CYP2D6 and CYP1A2 (Fig. 1) (Yu et al., 2003).
Ligand displaces heat shock protein 90 from overlapping binding sites within the aryl hydrocarbon receptor ligandbinding domain
2011, Journal of Biological Chemistry
- ☆
The research was funded in part by NIEHS Grant 09702, Center Grant ES01247, and a grant from the American Institute for Cancer Research. The data were presented in part at the 41st Annual Meeting of Society of Toxicology, March 2002, Nashville, Tennessee (Toxicol. Sci. 66 (1-S) 255).