Development of Novel CH223191-Based Antagonists of the Aryl Hydrocarbon Receptor

Abstract

Aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that regulates genes involved in drug/xenobiotic metabolism, cell cycle progression, cell fate determination, immune function, and inflammatory response. Increasing evidence that AHR plays a role in the pathophysiology of a number of human disease states is driving the need for improved pharmacological tools to be used for understanding the in vivo impact of AHR modulation. In this study, we have characterized and used structure-activity relationship analyses of a newly synthesized library of derivatives of the potent AHR antagonist 2-methyl-2H-pyrazole-3-carboxylic acid (2-methyl-4-o-tolylazo-phenyl)-amide (CH223191). Initial screening of these compounds revealed that those bearing groups with strong electronegativity at the R1 position (i.e., CHD-5, CHD-11, and CHD-12) versus those that are more electron-poor at this position (i.e., CHD-7 and CHD-8) elicited the most potent AHR antagonistic properties. The ability of these derivatives to inhibit agonist (2,3,7,8-tetrachlorodibenzo-p-dioxin) binding, nuclear translocation of AHR, and agonist-induced enzyme activity also were determined and support the initial findings. Furthermore, CH223191, but not CHD-5, CHD-11, or CHD-12, was found to exhibit AHR-independent proproliferative properties. These results contribute to our understanding of the structural requirements of potent AHR antagonists and the development of effective pharmacological tools to be used for studying the pathophysiological role of AHR.

PCB126 inhibits adipogenesis of human preadipocytes

“…To determine whether the observed inhibition of differentiation by PCB126 was through the AhR, we utilized an AhR antagonist CH223191 (Choi et al, 2012). Co-incubation of pre-adipocytes during the PCB126 pre-exposure period with CH223191 prevented upregulation of CYP1A1 transcript levels, determined at the end of the differentiation period (Figure 5C, Supplementary Table I).…”

Mono-substituted isopropylated triaryl phosphate, a major component of Firemaster 550, is an AHR agonist that exhibits AHR-independent cardiotoxicity in zebrafish

“…First identified through a chemical library screen (Kim et al , 2006), CH223191 has also been used as a pharmacologic tool to study the toxicity of and AHR interactions with androgenic anabolic steroids, certain PAHs, and most recently mITP and TPP (Gramatzki et al , 2009; McGee et al , 2013; Moon et al , 2012). However, CH223191 alone has been shown to cause AHR-independent cell proliferation in both human and murine hepatoma cell lines (Choi et al , 2012). Moreover, CH223191 antagonism is ligand-dependent as it does not antagonize certain PAHs, flavonoids and indirubin, including benzo(a)anthracene, benzo(k)fluoranthene, and β-Naphthoflavone (Zhao et al , 2010).…”

“…On the other hand, the CH223191 rescue of cardiotoxicity caused by mITP and not TPP may be a function of how CH223191 targets and possibly antagonizes other pathways. For instance, CH223191 may exhibit ligand-dependent antagonism with mITP and not TPP through an AHR-independent pathway, or may be a selective receptor modulator or allosteric regulator that results in exclusion of mITP and not TPP from a specific receptor-binding site (Choi et al , 2012). …”

Coplanar Polychlorinated Biphenyls Impair Glucose Homeostasis in Lean C57BL/6 Mice and Mitigate Beneficial Effects of Weight Loss on Glucose Homeostasis in Obese Mice

“…To determine whether in vivo effects were AhR-mediated, we fed male C57BL/6 mice (2 months of age; n = 7/group) the LF diet and orally gavaged them with vehicle or CH-223191 daily (10 mg/kg/day) (Kim et al 2006; Choi et al 2012) starting 1 week before administration of vehicle or PCB-77 and through the remainder of the study. After 1 week of pretreatment with CH-233191, mice were administered vehicle or PCB-77 (50 mg/kg by oral gavage, given as two separate doses in weeks 1 and 2).…”