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Current Therapeutic Landscape and Safety Roadmap for Targeting the Aryl Hydrocarbon Receptor in Inflammatory Gastrointestinal Indications. Cells 2022; 11:cells11101708. [PMID: 35626744 PMCID: PMC9139855 DOI: 10.3390/cells11101708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/30/2022] [Accepted: 05/16/2022] [Indexed: 02/07/2023] Open
Abstract
Target modulation of the AhR for inflammatory gastrointestinal (GI) conditions holds great promise but also the potential for safety liabilities both within and beyond the GI tract. The ubiquitous expression of the AhR across mammalian tissues coupled with its role in diverse signaling pathways makes development of a “clean” AhR therapeutically challenging. Ligand promiscuity and diversity in context-specific AhR activation further complicates targeting the AhR for drug development due to limitations surrounding clinical translatability. Despite these concerns, several approaches to target the AhR have been explored such as small molecules, microbials, PROTACs, and oligonucleotide-based approaches. These various chemical modalities are not without safety liabilities and require unique de-risking strategies to parse out toxicities. Collectively, these programs can benefit from in silico and in vitro methodologies that investigate specific AhR pathway activation and have the potential to implement thresholding parameters to categorize AhR ligands as “high” or “low” risk for sustained AhR activation. Exploration into transcriptomic signatures for AhR safety assessment, incorporation of physiologically-relevant in vitro model systems, and investigation into chronic activation of the AhR by structurally diverse ligands will help address gaps in our understanding regarding AhR-dependent toxicities. Here, we review the role of the AhR within the GI tract, novel therapeutic modality approaches to target the AhR, key AhR-dependent safety liabilities, and relevant strategies that can be implemented to address drug safety concerns. Together, this review discusses the emerging therapeutic landscape of modalities targeting the AhR for inflammatory GI indications and offers a safety roadmap for AhR drug development.
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Zhang W, Xie HQ, Li Y, Zhou M, Zhou Z, Wang R, Hahn ME, Zhao B. The aryl hydrocarbon receptor: A predominant mediator for the toxicity of emerging dioxin-like compounds. JOURNAL OF HAZARDOUS MATERIALS 2022; 426:128084. [PMID: 34952507 PMCID: PMC9039345 DOI: 10.1016/j.jhazmat.2021.128084] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/29/2021] [Accepted: 12/12/2021] [Indexed: 06/01/2023]
Abstract
The aryl hydrocarbon receptor (AHR) is a member of the basic helix-loop-helix/Per-ARNT-Sim (bHLH-PAS) family of transcription factors and has broad biological functions. Early after the identification of the AHR, most studies focused on its roles in regulating the expression of drug-metabolizing enzymes and mediating the toxicity of dioxins and dioxin-like compounds (DLCs). Currently, more diverse functions of AHR have been identified, indicating that AHR is not just a dioxin receptor. Dioxins and DLCs occur ubiquitously and have diverse health/ecological risks. Additional research is required to identify both shared and compound-specific mechanisms, especially for emerging DLCs such as polyhalogenated carbazoles (PHCZs), polychlorinated diphenyl sulfides (PCDPSs), and others, of which only a few investigations have been performed at present. Many of the toxic effects of emerging DLCs were observed to be predominantly mediated by the AHR because of their structural similarity as dioxins, and the in vitro TCDD-relative potencies of certain emerging DLC congeners are comparable to or even greater than the WHO-TEFs of OctaCDD, OctaCDF, and most coplanar PCBs. Due to the close relationship between AHR biology and environmental science, this review begins by providing novel insights into AHR signaling (canonical and non-canonical), AHR's biochemical properties (AHR structure, AHR-ligand interaction, AHR-DNA binding), and the variations during AHR transactivation. Then, AHR ligand classification and the corresponding mechanisms are discussed, especially the shared and compound-specific, AHR-mediated effects and mechanisms of emerging DLCs. Accordingly, a series of in vivo and in vitro toxicity evaluation methods based on the AHR signaling pathway are reviewed. In light of current advances, future research on traditional and emerging DLCs will enhance our understanding of their mechanisms, toxicity, potency, and ecological impacts.
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Affiliation(s)
- Wanglong Zhang
- College of Life Sciences, Qufu Normal University, Qufu, Shandong 273165, China
| | - Heidi Qunhui Xie
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yunping Li
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mingxi Zhou
- Biology Centre of the Czech Academy of Sciences v.v.i, Institute of Plant Molecular Biology, Branišovská 31, 370 05 České Budějovice, Czech Republic
| | - Zhiguang Zhou
- State Environmental Protection Key Laboratory of Dioxin Pollution Control, National Research Center for Environmental Analysis and Measurement, Beijing 100029, China
| | - Renjun Wang
- College of Life Sciences, Qufu Normal University, Qufu, Shandong 273165, China
| | - Mark E Hahn
- Biology Department, Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA 02543, USA; Boston University Superfund Research Program, Boston University, Boston, MA 02118, USA
| | - Bin Zhao
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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O'Donnell EF, Jang HS, Liefwalker DF, Kerkvliet NI, Kolluri SK. Discovery and Mechanistic Characterization of a Select Modulator of AhR-regulated Transcription (SMAhRT) with Anti-cancer Effects. Apoptosis 2021; 26:307-322. [PMID: 33893898 DOI: 10.1007/s10495-021-01666-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/12/2021] [Indexed: 02/07/2023]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor and a member of the bHLH/PAS (basic Helix-Loop-Helix/Per-Arnt-Sim) family of proteins. The AhR was cloned and characterized for its role in mediating the toxicity of dioxins. Subsequent research has identified the role of AhR in suppression of cancer cell growth. We hypothesized that the AhR is a molecular target for therapeutic intervention in cancer, and that activation of the AhR by unique AhR ligands in cancer cells could have anti-cancer effects including induction of cell death. This study describes the discovery and characterization of a new class of anti-cancer agents targeting the AhR, that we designate as Select Modulators of AhR-regulated Transcription (SMAhRTs). We employed two independent small molecule screening approaches to identify potential SMAhRTs. We report the identification of CGS-15943 that activates AhR signaling and induces apoptosis in an AhR-dependent manner in liver and breast cancer cells. Investigation of the downstream signaling pathway of this newly identified SMAhRT revealed upregulation of Fas-ligand (FasL), which is required for AhR-mediated apoptosis. Our results provide a basis for further development of a new class of anti-cancer therapeutics targeting an underappreciated molecular target, the AhR.
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Affiliation(s)
- Edmond Francis O'Donnell
- Cancer Research Laboratory, Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, 97331, USA
- Department of Orthopaedic Surgery, University of California Davis Medical Center, Davis, CA, USA
| | - Hyo Sang Jang
- Cancer Research Laboratory, Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, 97331, USA
| | - Daniel F Liefwalker
- Cancer Research Laboratory, Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, 97331, USA
- Department of Molecular and Medical Genetics, School of Medicine, Oregon Health and Science University, Portland, OR, USA
| | - Nancy I Kerkvliet
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, 97331, USA
- The Pacific Northwest Center for Translational Environmental Health Research, Oregon State University, Corvallis, OR, 97331, USA
| | - Siva Kumar Kolluri
- Cancer Research Laboratory, Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, 97331, USA.
- Linus Pauling Institute, Oregon State University, Corvallis, OR, 97331, USA.
- Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, 97331, USA.
- The Pacific Northwest Center for Translational Environmental Health Research, Oregon State University, Corvallis, OR, 97331, USA.
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Bian Y, Li Y, Shrestha G, Wen X, Cai B, Wang K, Wan X. ITE, an endogenous aryl hydrocarbon receptor ligand, suppresses endometrial cancer cell proliferation and migration. Toxicology 2019; 421:1-8. [PMID: 30953668 DOI: 10.1016/j.tox.2019.03.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Revised: 02/16/2019] [Accepted: 03/29/2019] [Indexed: 01/16/2023]
Abstract
BACKGROUND Identification of new molecular targets for the treatment of endometrial cancer (EC) is an important clinical goal, especially for the patients which were resistant to conventional therapies. The aryl hydrocarbon receptor (AhR) is a ligand- activated transcription factor known primarily as the mediator of dioxin toxicity. However, the AhR can also inhibit cellular proliferation in a ligand-dependent manner and act as a tumor suppressor in mice, thus may be a potential anticancer target. In this study, we investigated if the endogenous AhR ligand 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE) regulated proliferation and migration of EC cells via AhR. METHODS We used quantitative real-time PCR and western blot to assess the expression of AhR in EC tissues and paired adjacent normal tissues. In addition, we conducted transwell assay to test whether the treatment of ITE altered the locomotive potential and proliferation of EC cells. Next, we conducted mouse xenograft models to further explore the in vivo effect of ITE. RESULTS We found that the AhR protein and RNA levels were increased mildly in EC tissues relative to the para-tumor normal endometrial tissues. Besides, ITE suppressed EC cells proliferation and migration in vitro, and also suppressed EC cells xenograft growth in mice. CONCLUSIONS Our results strongly supported the possibility of using the ITE as a small molecular compound for the treatment of EC.
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Affiliation(s)
- Yiding Bian
- Clinical and Translational Research Center, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, PR China
| | - Yiran Li
- Department of Gynecology, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, PR China
| | - Garima Shrestha
- Clinical and Translational Research Center, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, PR China
| | - Xiaoli Wen
- Clinical and Translational Research Center, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, PR China
| | - Bailian Cai
- Clinical and Translational Research Center, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, PR China
| | - Kai Wang
- Clinical and Translational Research Center, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, PR China.
| | - Xiaoping Wan
- Department of Gynecology, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, PR China.
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Ponce-Ruiz N, Murillo-González FE, Rojas-García AE, Mackness M, Bernal-Hernández YY, Barrón-Vivanco BS, González-Arias CA, Medina-Díaz IM. Transcriptional regulation of human Paraoxonase 1 by nuclear receptors. Chem Biol Interact 2017; 268:77-84. [PMID: 28223025 DOI: 10.1016/j.cbi.2017.02.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 02/10/2017] [Indexed: 01/08/2023]
Abstract
Paraoxonase 1 (PON1) is a calcium-dependent lactonase synthesized primarily in the liver and secreted into the plasma, where it is associates with high density lipoproteins (HDL). PON1 acts as antioxidant preventing low-density lipoprotein (LDL) oxidation, a process considered critical in the initiation and progression of atherosclerosis. Additionally, PON1 hydrolyzes and detoxifies some toxic metabolites of organophosphorus compounds (OPs). Thus, PON1 activity and expression levels are important for determining susceptibility to OPs intoxication and risk of developing diseases related to inflammation and oxidative stress. Increasing evidence has demonstrated the modulation of PON1 expression by many factors is due to interaction with nuclear receptors (NRs). Here, we briefly review the studies in this area and discuss the role of nuclear receptors in the regulation of PON1 expression, as well as how understanding these mechanisms may allow us to manipulate PON1 levels to improve drug efficacy and treat disease.
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Affiliation(s)
- N Ponce-Ruiz
- Universidad Autónoma de Nayarit, Laboratorio de Contaminación y Toxicología, Secretaría de Investigación y Posgrado, Nayarit, Mexico; Posgrado en Ciencias Biológico Agropecuarias, Universidad Autónoma de Nayarit, Tepic, Nayarit, Mexico.
| | - F E Murillo-González
- Universidad Autónoma de Nayarit, Laboratorio de Contaminación y Toxicología, Secretaría de Investigación y Posgrado, Nayarit, Mexico; Posgrado en Ciencias Biológico Agropecuarias, Universidad Autónoma de Nayarit, Tepic, Nayarit, Mexico.
| | - A E Rojas-García
- Universidad Autónoma de Nayarit, Laboratorio de Contaminación y Toxicología, Secretaría de Investigación y Posgrado, Nayarit, Mexico.
| | - Mike Mackness
- Institute of Cardiovascular Sciences, Manchester, United Kingdom.
| | - Y Y Bernal-Hernández
- Universidad Autónoma de Nayarit, Laboratorio de Contaminación y Toxicología, Secretaría de Investigación y Posgrado, Nayarit, Mexico.
| | - B S Barrón-Vivanco
- Universidad Autónoma de Nayarit, Laboratorio de Contaminación y Toxicología, Secretaría de Investigación y Posgrado, Nayarit, Mexico.
| | - C A González-Arias
- Universidad Autónoma de Nayarit, Laboratorio de Contaminación y Toxicología, Secretaría de Investigación y Posgrado, Nayarit, Mexico.
| | - I M Medina-Díaz
- Universidad Autónoma de Nayarit, Laboratorio de Contaminación y Toxicología, Secretaría de Investigación y Posgrado, Nayarit, Mexico.
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Denison MS, Faber SC. And Now for Something Completely Different: Diversity in Ligand-Dependent Activation of Ah Receptor Responses. CURRENT OPINION IN TOXICOLOGY 2017; 2:124-131. [PMID: 28845473 PMCID: PMC5570615 DOI: 10.1016/j.cotox.2017.01.006] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Ligand-dependent activation of the Ah receptor (AhR) can result in an extremely diverse spectrum of biological and toxic effects that occur in a ligand-, species- and tissue-specific manner. While the classical mechanism of AhR-dependent signal transduction is directly related to its ability to modulate gene expression, the dramatic diversity in responses observed following AhR activation or inhibition is inconsistent with a single molecular mechanism of AhR action. Recent studies have revealed that key molecular events underlying the AhR signaling pathway are significantly more varied and complex than previously established, and the specificity and diversity in AhR response can be selectively modulated by a variety of factors. Here we describe new insights into the mechanistic diversity in AhR signal transduction that can contribute to ligand-, species- and tissue-specific differences in AhR reponse.
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Affiliation(s)
- Michael S Denison
- Department of Environmental Toxicology, University of California, Davis, CA, 95616, USA
| | - Samantha C Faber
- Department of Environmental Toxicology, University of California, Davis, CA, 95616, USA
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Wright EJ, De Castro KP, Joshi AD, Elferink CJ. Canonical and non-canonical aryl hydrocarbon receptor signaling pathways. CURRENT OPINION IN TOXICOLOGY 2017; 2:87-92. [PMID: 32296737 DOI: 10.1016/j.cotox.2017.01.001] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Decades of research on the Aryl hydrocarbon Receptor (AhR) has unveiled its involvement in the toxicity of halogenated and polycyclic aromatic hydrocarbons, and a myriad of normal physiological processes. The molecular dissection of AhR biology has centered on a canonical signaling pathway in an effort to mechanistically reconcile the diverse pathophysiological effects of exposure to environmental pollutants. As a consequence, we now know that canonical signaling can explain many but not all of the AhR-mediated effects. Here we describe recent findings that point to non-canonical signaling pathways, and focus on a novel AhR interaction with the Krüppel-like Factor 6 protein responsible for previously un-recognized epigenetic changes in the chromatin affecting gene expression.
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Affiliation(s)
- Eric J Wright
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555-0654, USA
| | - Karen Pereira De Castro
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555-0654, USA
| | - Aditya D Joshi
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555-0654, USA
| | - Cornelis J Elferink
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555-0654, USA
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Sustained expression of CYPs and DNA adduct accumulation with continuous exposure to PCB126 and PCB153 through a new delivery method: Polymeric implants. Toxicol Rep 2014; 1:820-833. [PMID: 25530946 PMCID: PMC4266188 DOI: 10.1016/j.toxrep.2014.09.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Polymeric implants successfully achieved continuous exposure to PCBs in rats. PCB126 resulted in significant oxidative DNA damage (8-oxodG) in rat liver and lung. PCB126 or in combination with PCB153 induced PON1 and its activity in the liver. The induction was even greater for PON3 and AhR gene transcription. Co-treatment reduced mammary PCB153 and increased liver PCB126 and PCB153 levels.
A new delivery method via polymeric implants was used for continuous exposure to PCBs. Female Sprague-Dawley rats received subcutaneous polymeric implants containing PCB126 (0.15% load), PCB153 (5% load), or both, for up to 45 d and release kinetics and tissue distribution were measured. PCB153 tissue levels on day 15 were readily detected in lung, liver, mammary and serum, with highest levels in the mammary tissue. PCB126 was detected only in liver and mammary tissues. However, a completely different pharmacokinetics was observed on co-exposure of PCB153 and PCB126, with a 1.8-fold higher levels of PCB153 in the liver whereas a 1.7-fold lower levels in the mammary tissue. PCB126 and PCB153 caused an increase in expression of key PCB-inducible enzymes, CYP 1A1/2 and 2B1/2, respectively. Serum and liver activities of the antioxidant enzymes, PON1 and PON3, and AhR transcription were also significantly increased by PCB126. 32P-postlabeling for polar and lipophilic DNA-adducts showed significant quantitative differences: PCB126 increased 8-oxodG, an oxidative DNA lesion, in liver and lung tissues. Adduct levels in the liver remained upregulated up to 45 d, while some lung DNA adducts declined. This is the first demonstration that continuous low-dose exposure to PCBs via implants can produce sustained tissue levels leading to the accumulation of DNA-adducts in target tissue and induction of indicator enzymes. Collectively, these data demonstrate that this exposure model is a promising tool for long-term exposure studies.
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