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Qin C, Aslamkhan AG, Pearson K, Tanis KQ, Podtelezhnikov A, Frank E, Pacchione S, Pippert T, Glaab WE, Sistare FD. AhR Activation in Pharmaceutical Development: Applying Liver Gene Expression Biomarker Thresholds to Identify Doses Associated with Tumorigenic Risks in Rats. Toxicol Sci 2019; 171:46-55. [PMID: 31127949 DOI: 10.1093/toxsci/kfz125] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 05/16/2019] [Accepted: 05/18/2019] [Indexed: 12/13/2022] Open
Abstract
Aryl hydrocarbon receptor (AhR) activation is associated with carcinogenicity of non-genotoxic AhR-activating carcinogens such as 2, 3, 7, 8-tetrachlorodibenzodioxin (TCDD), and is often observed with drug candidate molecules in development and raises safety concerns. As downstream effectors of AhR signaling, the expression and activity of Cyp1a1 and Cyp1a2 genes are commonly monitored as evidence of AhR activation to inform carcinogenic risk of compounds in question. However, many marketed drugs and phytochemicals are reported to induce these Cyps modestly and are not associated with dioxin-like toxicity or carcinogenicity. We hypothesized that a threshold of AhR activation needs to be surpassed in a sustained manner in order for the dioxin-like toxicity to manifest, and a simple liver gene expression signature based on Cyp1a1 and Cyp1a2 from a short-term rat study could be used to assess AhR activation strength and differentiate tumorigenic dose levels from non-tumorigenic ones. To test this hypothesis, short term studies were conducted in Wistar Han rats with two AhR-activating carcinogens (TCDD and PCB126) at minimally carcinogenic and non-carcinogenic dose levels, and three AhR-activating non-carcinogens (omeprazole, mexiletine, and canagliflozin) at the top doses used in their reported 2-year rat carcinogenicity studies. A threshold of AhR activation was identified in rat liver that separated a meaningful "tumorigenic-strength AhR signal" from a statistically-significant AhR activation signal that was not associated with dioxin-like carcinogenicity. These studies also confirmed the importance of the sustainability of AhR activation for carcinogenic potential. A sustained activation of AhR above the threshold could thus be used in early pharmaceutical development to identify dose levels of drug candidates expected to exhibit dioxin-like carcinogenic potential.
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Affiliation(s)
- Chunhua Qin
- Department of Safety Assessment and Laboratory Animal Resources, Merck & Co. Inc., West Point, PA, USA
| | - Amy G Aslamkhan
- Department of Safety Assessment and Laboratory Animal Resources, Merck & Co. Inc., West Point, PA, USA
| | - Kara Pearson
- Department of Safety Assessment and Laboratory Animal Resources, Merck & Co. Inc., West Point, PA, USA
| | - Keith Q Tanis
- Department of Human Genetics and Pharmacogenomics, Merck & Co. Inc., West Point, PA, USA
| | - Alexei Podtelezhnikov
- Department of Human Genetics and Pharmacogenomics, Merck & Co. Inc., West Point, PA, USA
| | - Erika Frank
- Department of Safety Assessment and Laboratory Animal Resources, Merck & Co. Inc., West Point, PA, USA
| | - Stephen Pacchione
- Department of Safety Assessment and Laboratory Animal Resources, Merck & Co. Inc., West Point, PA, USA
| | - Todd Pippert
- Department of Safety Assessment and Laboratory Animal Resources, Merck & Co. Inc., West Point, PA, USA
| | - Warren E Glaab
- Department of Safety Assessment and Laboratory Animal Resources, Merck & Co. Inc., West Point, PA, USA
| | - Frank D Sistare
- Department of Safety Assessment and Laboratory Animal Resources, Merck & Co. Inc., West Point, PA, USA
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Dunnick JK, Pandiri AR, Merrick BA, Kissling GE, Cunny H, Mutlu E, Waidyanatha S, Sills R, Hong HL, Ton TV, Maynor T, Recio L, Phillips SL, Devito MJ, Brix A. Carcinogenic activity of pentabrominated diphenyl ether mixture (DE-71) in rats and mice. Toxicol Rep 2018; 5:615-624. [PMID: 29868454 PMCID: PMC5984199 DOI: 10.1016/j.toxrep.2018.05.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 05/11/2018] [Accepted: 05/14/2018] [Indexed: 01/19/2023] Open
Abstract
Pentabrominated diphenyl ether (PBDE) mixture was a multispecies carcinogen causing liver tumors in male and female rats and mice. Hras or Ctnnb1 mutations characterized the PBDE-induced liver tumors. PBDE-induced liver tumors increased with increasing PBDE exposure.
Pentabrominated diphenyl ether (PBDE) flame retardants have been phased out in Europe and in the United States, but these lipid soluble chemicals persist in the environment and are found human and animal tissues. PBDEs have limited genotoxic activity. However, in a 2-year cancer study of a PBDE mixture (DE-71) (0, 3, 15, or 50 mg/kg (rats); 0, 3, 30, or 100 mg/kg (mice)) there were treatment-related liver tumors in male and female Wistar Han rats [Crl:WI(Han) after in utero/postnatal/adult exposure, and in male and female B6C3F1 mice, after adult exposure. In addition, there was evidence for a treatment-related carcinogenic effect in the thyroid and pituitary gland tumor in male rats, and in the uterus (stromal polyps/stromal sarcomas) in female rats. The treatment-related liver tumors in female rats were unrelated to the AhR genotype status, and occurred in animals with wild, mutant, or heterozygous Ah receptor. The liver tumors in rats and mice had treatment-related Hras and Ctnnb mutations, respectively. The PBDE carcinogenic activity could be related to oxidative damage, disruption of hormone homeostasis, and molecular and epigenetic changes in target tissue. Further work is needed to compare the PBDE toxic effects in rodents and humans.
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Affiliation(s)
- J K Dunnick
- National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - A R Pandiri
- National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - B A Merrick
- National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - G E Kissling
- National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - H Cunny
- National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - E Mutlu
- National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - S Waidyanatha
- National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - R Sills
- National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - H L Hong
- National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - T V Ton
- National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - T Maynor
- Integrated Laboratory Systems, Research Triangle Park, NC 27709, USA
| | - L Recio
- Integrated Laboratory Systems, Research Triangle Park, NC 27709, USA
| | - S L Phillips
- Integrated Laboratory Systems, Research Triangle Park, NC 27709, USA
| | - M J Devito
- National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - A Brix
- EPL, Inc., Research Triangle Park, NC 27709, USA
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Budhwar S, Bahl C, Sharma S, Singh N, Behera D. Role of Sequence Variations in AhR Gene Towards Modulating Smoking Induced Lung Cancer Susceptibility in North Indian Population: A Multiple Interaction Analysis. Curr Genomics 2018; 19:313-326. [PMID: 29755293 PMCID: PMC5930452 DOI: 10.2174/1389202918666170915160606] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 06/28/2017] [Accepted: 06/28/2017] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND AhR, a ubiquitously expressed ligand-activated transcription factor, upon its encounter with the foreign ligands activates the transcriptional machinery of genes encoding for bio-transformation enzymes like CYP1A1 hence, mediating the metabolism of Poly aromatic hydrocarbons and nitrosamines which account for the maximally found carcinogen in cigarette smoke. Polymorphic variants of AhR play a significant role and are held responsible for disposing the individuals with greater chances of acquiring lung cancer. OBJECTIVE To study the role of AhR variants (rs2282885, rs10250822, rs7811989, rs2066853) in affect-ing lung cancer susceptibility. METHODS 297 cases and 320 controls have been genotyped using PCR-RFLP technique. In order to find out the association, unconditional logistic regression approach was used. To analyze high order in-teractions Multifactor Dimensionality Reduction and Classification and regression tree was used. RESULTS Subjects carrying the variant genotype for AhR rs7811989 showed a two-fold risk (p=0.007) and a marginal risk was also seen in case of individuals carrying either single or double copy of suscep-tible allele for rs102550822 (p=0.02). Whereas the variant allele for rs2066853 showcased a strong pro-tective effect (p=0.003). SQCC individuals with mutant genotype of rs2066853 also exhibited a protec-tive effect towards lung cancer (OR=0.30, p=0.0013). The association of rs7811989 mutant genotype and rs10250822 mutant genotype was evident especially in smokers as compared to non-smokers. AhR rs2066853 showed a decreased risk in smokers with mutant genotype (p=0.002). MDR approach gave the best interaction model of AhR rs2066853 and smoking (CVC=10/10, prediction error=0.42). CONCLUSION AhR polymorphic variations can significantly contribute towards lung cancer predisposi-tion.
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Affiliation(s)
- Sneha Budhwar
- Department of Biotechnology, Thapar University, Patiala, Punjab-147002, India
| | - Charu Bahl
- Department of Biotechnology, Thapar University, Patiala, Punjab-147002, India
| | - Siddharth Sharma
- Department of Biotechnology, Thapar University, Patiala, Punjab-147002, India
| | - Navneet Singh
- Department of Pulmonary Medicine, Post Graduate Institute of Medical Education and Research (PGIMER), Sector 14, Chandigarh, India
| | - Digambar Behera
- Department of Pulmonary Medicine, Post Graduate Institute of Medical Education and Research (PGIMER), Sector 14, Chandigarh, India
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Safarinejad MR, Shafiei N, Safarinejad S. Polymorphisms in Aryl Hydrocarbon Receptor Gene Are Associated With Idiopathic Male Factor Infertility. Reprod Sci 2013; 20:1423-32. [DOI: 10.1177/1933719113488451] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Mohammad Reza Safarinejad
- Clinical Center for Urological Disease Diagnosis and Private Clinic Specialized in Urological and Andrological Genetics, Tehran, Iran
| | - Nayyer Shafiei
- Clinical Center for Urological Disease Diagnosis and Private Clinic Specialized in Urological and Andrological Genetics, Tehran, Iran
| | - Saba Safarinejad
- Clinical Center for Urological Disease Diagnosis and Private Clinic Specialized in Urological and Andrological Genetics, Tehran, Iran
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Bradshaw TD, Bell DR. Relevance of the aryl hydrocarbon receptor (AhR) for clinical toxicology. Clin Toxicol (Phila) 2009; 47:632-42. [PMID: 19640236 DOI: 10.1080/15563650903140423] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
INTRODUCTION The aryl hydrocarbon receptor (AhR) is a cellular signaling molecule infamous for mediating the toxicity of dioxins and related compounds. AIM The aim of this review is to provide a background of AhR and to examine critically its role in chemical toxicity, in physiological systems, and its interaction with drugs and other compounds. TOXICITY The AhR is essential for the toxicity of dioxins and related chemicals. The AhR mediates the exquisite sensitivity of animals to dioxins, where as little as 2 ng/kg/day can yield striking adverse effects. PHYSIOLOGICAL ROLE OF AHR: The wide variety of adverse effects of dioxin argues for an important role of the AhR in a variety of physiological systems. Recent investigations have highlighted the role of AhR in the development of the brain and vasculature. DRUGS AND OTHER CHEMICAL ACTIVATORS OF AHR: The development of AhR agonists during drug development programs is sometimes inadvertent, but sometimes the target of development, and is yet further confirmation of the likely importance of AhR signaling in constitutive physiology. The presence of AhR agonists in the diet such as indolo-(3,2-b)-carbazole and 3,3'-diindolylmethane (metabolized from indole 3-carbinol), flavonoids, and sulforaphane and of endogenous activators of this signaling system such as eicosanoids, indirubin, bilirubin, cAMP, and tryptophan are suggestive that AhR activation is a normal physiological process and that it is the persistent and high-level stimulation of AhR by dioxins that is responsible for toxicity. CONCLUSIONS AhR-mediated toxicity and physiology are highly relevant to clinical toxicology and drug development.
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