RT Journal Article
SR Electronic
T1 Suppression of cytokine-mediated complement factor gene expression through selective activation of the Ah receptor with 3′, 4′-dimethoxy-α-naphthoflavone
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP mol.110.069369
DO 10.1124/mol.110.069369
A1 Iain A Murray
A1 Colin A Flaveny
A1 Christopher R Chiaro
A1 Arun K Sharma
A1 Rachel S Tanos
A1 Jennifer C Schroeder
A1 Shantu G Amin
A1 William H Bisson
A1 Siva K Kolluri
A1 Gary H. Perdew
YR 2010
UL http://molpharm.aspetjournals.org/content/early/2010/12/02/mol.110.069369.abstract
AB We have previously characterized a class of aryl hydrocarbon receptor (AHR) ligand termed selective AHR modulators (SAhRMs). SAhRMs exhibit anti-inflammatory properties, including suppression of cytokine-mediated acute phase genes (e.g. Saa1), through dissociation of non-dioxin response element (DRE) AHR activity from DRE-dependent xenobiotic gene expression. The partial AHR agonist α-naphthoflavone (αNF) mediates the suppressive, non-DRE dependent effects on SAA1 expression and partial DRE-mediated CYP1A1 induction. These observations suggest αNF may be structurally modified to a derivative exhibiting only SAhRM activity. A screen of αNF derivatives identifies 3′, 4′-dimethoxy-αNF (DiMNF) as a candidate SAhRM. Competitive ligand binding validates DiMNF as an AHR ligand, and DRE-dependent reporter assays with quantitative mRNA analysis of AHR target genes reveal minimal agonist activity associated with AHR binding. Consistent with loss of agonist activity, DiMNF fails to promote AHR binding to DRE probes as determined through EMSA. Importantly, mRNA analysis indicates that DiMNF retains the suppressive capacity of αNF regarding cytokine-mediated SAA1 expression in Huh7 cells. Interestingly, predictive docking modeling suggests that DiMNF adopts a unique orientation within the AHR ligand binding pocket relative to αNF and may facilitate the rational design of additional SAhRMs. Microarray studies with a non-DRE binding but otherwise functional AHR mutant identified complement factor C3 as a potential SAhRM target. We confirmed this observation in Huh7 cells using 10 μM DiMNF, which significantly repressed C3 mRNA and protein. These data expand the classes of AHR ligands exerting DRE-independent anti-inflammatory SAhRM activity, suggesting SAhRMs may have application in the amelioration of inflammatory disorders.