1
|
Fan Y, Chen L, Jing Q, Li X, Pan H, Fang C, Zhang J, Shi F. Covalent Binding of Reactive Anhydride of Cantharidin to Biological Amines. Drug Metab Dispos 2024; 52:775-784. [PMID: 38811155 DOI: 10.1124/dmd.123.001637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 04/30/2024] [Accepted: 05/19/2024] [Indexed: 05/31/2024] Open
Abstract
Cantharidin is a terpenoid from coleoptera beetles. Cantharidin has been used to treat molluscum contagiosum and some types of tumors. Cantharidin is highly toxic, and cantharidin poisoning and fatal cases have been reported worldwide. The mechanisms underlying cantharidin-induced toxicity remain unclear. Cantharidin contains anhydride, which may react with biologic amines. This study aimed to examine the chemical reactivity of cantharidin toward nucleophiles and characterize adducts of cantharidin with biologic amines in vitro and in mice. Here two types of conjugates were formed in the incubation of cantharidin under physiologic conditions with free amino acids, a mimic peptide, or amine-containing compounds, respectively. Amide-type conjugates were produced by the binding of cantharidin anhydride with the primary amino group of biologic amines. Imide-type conjugates were generated from the dehydration and cyclization of amide-type conjugates. The structure of the conjugates was characterized by using high-resolution mass spectrometry. We introduced the 14N/15N and 79Br/81Br isotope signatures to confirm the formation of conjugates using L-(ε)15N-lysine, L-lysine-15N2, and bromine-tagged hydrazine, respectively. The structure of imide conjugate was also confirmed by nuclear magnetic resonance experiments. Furthermore, the amide and imide conjugates of cantharidin with amino acids or N-acetyl-lysine were detected in mouse liver and urine. Cantharidin was found to modify lysine residue proteins in mouse liver. Pan-cytochrome P450 inhibitor 1-aminobenzotriazole significantly increased the urine cantharidin-N-acetyl-lysine conjugates, whereas it decreased cantharidin metabolites. In summary, cantharidin anhydride can covalently bind to biologic amines nonenzymatically, which facilitates a better understanding of the role of nonenzymatic reactivity in cantharidin poisoning. SIGNIFICANCE STATEMENT: Anhydride moiety of cantharidin can covalently bind to the primary amino group of biological amines nonenzymatically. Amide and imide conjugates were generated after the covalent binding of cantharidin anhydride with the primary amino groups of amino acids, a mimic peptide, and protein lysine residues. The structure of conjugates was confirmed by 14N/15N and 79Br/81Br isotope signatures using isotope-tagged reagents and nuclear magnetic resonance experiments. This study will facilitate the understanding of the role of nonenzymatic reactivity in cantharidin poisoning.
Collapse
Affiliation(s)
- Yaya Fan
- Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education (Y.F., L.C., Q.J., X.L., H.P., C.F., F.S.), Department of Clinical Pharmacy (H.P.), and Department of Pharmaceutical Analysis (J.Z.), Zunyi Medical University, Zunyi, China; and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China (C.F.)
| | - Lin Chen
- Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education (Y.F., L.C., Q.J., X.L., H.P., C.F., F.S.), Department of Clinical Pharmacy (H.P.), and Department of Pharmaceutical Analysis (J.Z.), Zunyi Medical University, Zunyi, China; and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China (C.F.)
| | - Qiuyi Jing
- Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education (Y.F., L.C., Q.J., X.L., H.P., C.F., F.S.), Department of Clinical Pharmacy (H.P.), and Department of Pharmaceutical Analysis (J.Z.), Zunyi Medical University, Zunyi, China; and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China (C.F.)
| | - Xiaoli Li
- Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education (Y.F., L.C., Q.J., X.L., H.P., C.F., F.S.), Department of Clinical Pharmacy (H.P.), and Department of Pharmaceutical Analysis (J.Z.), Zunyi Medical University, Zunyi, China; and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China (C.F.)
| | - Hong Pan
- Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education (Y.F., L.C., Q.J., X.L., H.P., C.F., F.S.), Department of Clinical Pharmacy (H.P.), and Department of Pharmaceutical Analysis (J.Z.), Zunyi Medical University, Zunyi, China; and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China (C.F.)
| | - Chao Fang
- Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education (Y.F., L.C., Q.J., X.L., H.P., C.F., F.S.), Department of Clinical Pharmacy (H.P.), and Department of Pharmaceutical Analysis (J.Z.), Zunyi Medical University, Zunyi, China; and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China (C.F.)
| | - Jianyong Zhang
- Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education (Y.F., L.C., Q.J., X.L., H.P., C.F., F.S.), Department of Clinical Pharmacy (H.P.), and Department of Pharmaceutical Analysis (J.Z.), Zunyi Medical University, Zunyi, China; and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China (C.F.)
| | - Fuguo Shi
- Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education (Y.F., L.C., Q.J., X.L., H.P., C.F., F.S.), Department of Clinical Pharmacy (H.P.), and Department of Pharmaceutical Analysis (J.Z.), Zunyi Medical University, Zunyi, China; and Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China (C.F.)
| |
Collapse
|
2
|
Ding X, Han J, Van Winkle LS, Zhang QY. Detection of Transgene Location in the CYP2A13/2B6/2F1-transgenic Mouse Model using Optical Genome Mapping Technology. Drug Metab Dispos 2023; 51:46-53. [PMID: 36273825 PMCID: PMC9832375 DOI: 10.1124/dmd.122.001090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 10/01/2022] [Accepted: 10/04/2022] [Indexed: 01/14/2023] Open
Abstract
Most transgenic mouse models are generated through random integration of the transgene. The location of the transgene provides valuable information for assessing potential effects of the transgenesis on the host and for designing genotyping protocols that can amplify across the integration site, but it is challenging to identify. Here, we report the successful utility of optical genome mapping technology to identify the transgene insertion site in a CYP2A13/2B6/2F1-transgenic mouse model, which produces three human cytochrome P450 (P450) enzymes (CYP2A13, CYP2B6, and CYP2F1) that are encoded by neighboring genes on human chromosome 19. These enzymes metabolize many drugs, respiratory toxicants, and chemical carcinogens. Initial efforts to identify candidate insertion sites by whole genome sequencing was unsuccessful, apparently because the transgene is located in a region of the mouse genome that contains highly repetitive sequences. Subsequent utility of the optical genome mapping approach, which compares genome-wide marker distribution between the transgenic mouse genome and a reference mouse (GRCm38) or human (GRCh38) genome, localized the insertion site to mouse chromosome 14, between two marker positions at 4451324 base pair and 4485032 base pair. A transgene-mouse genome junction sequence was further identified through long-polymerase chain reaction amplification and DNA sequencing at GRCm38 Chr.14:4484726. The transgene insertion (∼2.4 megabase pair) contained 5-7 copies of the human transgenes, which replaced a 26.9-33.4 kilobase pair mouse genomic region, including exons 1-4 of Gm3182, a predicted and highly redundant gene. Finally, the sequencing results enabled the design of a new genotyping protocol that can distinguish between hemizygous and homozygous CYP2A13/2B6/2F1-transgenic mice. SIGNIFICANCE STATEMENT: This study characterizes the genomic structure of, and provides a new genotyping method for, a transgenic mouse model that expresses three human P450 enzymes, CYP2A13, CYP2B6, and CYP2F1, that are important in xenobiotic metabolism and toxicity. The demonstrated success in applying the optical genome mapping technology for identification of transgene insertion sites should encourage others to do the same for other transgenic models generated through random integration, including most of the currently available human P450 transgenic mouse models.
Collapse
Affiliation(s)
- Xinxin Ding
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona (X.D., J.H., Q.-Y.Z.) and Center for Health and the Environment and Department of Anatomy Physiology and Cell Biology, School of Veterinary Medicine, UC Davis, Davis, California (L.S.V.W.)
| | - John Han
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona (X.D., J.H., Q.-Y.Z.) and Center for Health and the Environment and Department of Anatomy Physiology and Cell Biology, School of Veterinary Medicine, UC Davis, Davis, California (L.S.V.W.)
| | - Laura S Van Winkle
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona (X.D., J.H., Q.-Y.Z.) and Center for Health and the Environment and Department of Anatomy Physiology and Cell Biology, School of Veterinary Medicine, UC Davis, Davis, California (L.S.V.W.)
| | - Qing-Yu Zhang
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona (X.D., J.H., Q.-Y.Z.) and Center for Health and the Environment and Department of Anatomy Physiology and Cell Biology, School of Veterinary Medicine, UC Davis, Davis, California (L.S.V.W.)
| |
Collapse
|
3
|
Kelty J, Kovalchuk N, Uwimana E, Yin L, Ding X, Van Winkle L. In vitro airway models from mice, rhesus macaques, and humans maintain species differences in xenobiotic metabolism and cellular responses to naphthalene. Am J Physiol Lung Cell Mol Physiol 2022; 323:L308-L328. [PMID: 35853015 PMCID: PMC9423729 DOI: 10.1152/ajplung.00349.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 04/04/2022] [Accepted: 07/01/2022] [Indexed: 11/22/2022] Open
Abstract
The translational value of high-throughput toxicity testing will depend on pharmacokinetic validation. Yet, popular in vitro airway epithelia models were optimized for structure and mucociliary function without considering the bioactivation or detoxification capabilities of lung-specific enzymes. This study evaluated xenobiotic metabolism maintenance within differentiated air-liquid interface (ALI) airway epithelial cell cultures (human bronchial; human, rhesus, and mouse tracheal), isolated airway epithelial cells (human, rhesus, and mouse tracheal; rhesus bronchial), and ex vivo microdissected airways (rhesus and mouse) by measuring gene expression, glutathione content, and naphthalene metabolism. Glutathione levels and detoxification gene transcripts were measured after 1-h exposure to 80 µM naphthalene (a bioactivated toxicant) or reactive naphthoquinone metabolites. Glutathione and glutathione-related enzyme transcript levels were maintained in ALI cultures from all species relative to source tissues, while cytochrome P450 monooxygenase gene expression declined. Notable species differences among the models included a 40-fold lower total glutathione content for mouse ALI trachea cells relative to human and rhesus; a higher rate of naphthalene metabolism in mouse ALI cultures for naphthalene-glutathione formation (100-fold over rhesus) and naphthalene-dihydrodiol production (10-fold over human); and opposite effects of 1,2-naphthoquinone exposure in some models-glutathione was depleted in rhesus tissue but rose in mouse ALI samples. The responses of an immortalized bronchial cell line to naphthalene and naphthoquinones were inconsistent with those of human ALI cultures. These findings of preserved species differences and the altered balance of phase I and phase II xenobiotic metabolism among the characterized in vitro models should be considered for future pulmonary toxicity testing.
Collapse
Affiliation(s)
- Jacklyn Kelty
- Department of Anatomy, Physiology and Cell Biology, Center for Comparative Respiratory Biology and Medicine, School of Veterinary Medicine and Center for Health and the Environment, University of California at Davis, Davis, California
| | - Nataliia Kovalchuk
- Pharmacology and Toxicology Department, College of Pharmacy, University of Arizona, Tucson, Arizona
| | - Eric Uwimana
- Pharmacology and Toxicology Department, College of Pharmacy, University of Arizona, Tucson, Arizona
| | - Lei Yin
- Pharmacology and Toxicology Department, College of Pharmacy, University of Arizona, Tucson, Arizona
| | - Xinxin Ding
- Pharmacology and Toxicology Department, College of Pharmacy, University of Arizona, Tucson, Arizona
| | - Laura Van Winkle
- Department of Anatomy, Physiology and Cell Biology, Center for Comparative Respiratory Biology and Medicine, School of Veterinary Medicine and Center for Health and the Environment, University of California at Davis, Davis, California
| |
Collapse
|
4
|
Hannon SL, Ding X. Assessing cytochrome P450 function using genetically engineered mouse models. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2022; 95:253-284. [PMID: 35953157 PMCID: PMC10544722 DOI: 10.1016/bs.apha.2022.05.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The ability to knock out and/or humanize different genes in experimental animals, globally or in cell- and tissue-specific patterns, has revolutionized scientific research in many areas. Genetically engineered mouse models, including knockout models, transgenic models, and humanized models, have played important roles in revealing the in vivo functions of various cytochrome P450 (CYP) enzymes. These functions are very diverse, ranging from the biotransformation of drugs and other xenobiotics, events that often dictate their pharmacokinetic or toxicokinetic properties and the associated therapeutic or adverse actions, to the metabolism of endogenous compounds, such as steroid hormones and other bioactive substances, that may determine susceptibility to many diseases, such as cancer and metabolic diseases. In this review, we provide a comprehensive list of Cyp-knockout, human CYP-transgenic, and CYP-humanized mouse models that target genes in the CYP1-4 gene families, and highlight their utility in assessing the in vivo metabolism, bioactivation, and toxicity of various xenobiotic compounds, including therapeutic agents and chemical carcinogens. We aim to showcase the advantages of utilizing these mouse models for in vivo drug metabolism and toxicology studies, and to encourage and facilitate greater utility of engineered mouse models to further improve our knowledge of the in vivo functions of various P450 enzymes, which is integral to our ability to develop safer and more effective therapeutics and to identify individuals predisposed to adverse drug reactions or environmental diseases.
Collapse
Affiliation(s)
- Sarrah L Hannon
- Department of Pharmacology and Toxicology, Ken R. Coit College of Pharmacy, The University of Arizona, Tucson, AZ, United States
| | - Xinxin Ding
- Department of Pharmacology and Toxicology, Ken R. Coit College of Pharmacy, The University of Arizona, Tucson, AZ, United States.
| |
Collapse
|
5
|
Kovalchuk N, Zhang QY, Van Winkle L, Ding X. Contribution of Pulmonary CYP-mediated Bioactivation of Naphthalene to Airway Epithelial Injury in the Lung. Toxicol Sci 2021; 177:334-346. [PMID: 32974682 DOI: 10.1093/toxsci/kfaa114] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Previous studies have established that cytochrome P450 enzymes (CYPs) in both liver and lung are capable of bioactivating naphthalene (NA), an omnipresent air pollutant and possible human carcinogen, in vitro and in vivo. The aim of this study was to examine the specific contribution of pulmonary CYPs in airway epithelial cells to NA-induced airway toxicity. We used a lung-Cpr-null mouse model, which undergoes doxycycline-induced, Cre-mediated deletion of the Cpr (a redox partner of all microsomal CYPs) gene specifically in airway epithelial cells. In 2-month-old lung-Cpr-null mice, Cpr deletion occurred in 75%-82% of epithelial cells of conducting airways. The extent of NA-induced acute lung toxicity (as indicated by total protein concentration and lactate dehydrogenase activity in bronchoalveolar lavage fluid collected at 24-h after initiation of a 4-h, nose-only, 10-ppm NA inhalation exposure) was substantially lower (by 37%-39%) in lung-Cpr-null mice, compared with control littermates. Moreover, the extent of cellular proliferation (as indicated by 5-bromo-2'-deoxyuridine incorporation) was noticeably lower in both proximal and distal airways (by 59% and 65%, respectively) of NA-treated lung-Cpr-null mice, compared with control littermates, at 2-day post-NA inhalation exposure. A similar genotype-related difference in the extent of postexposure cell proliferation was also observed in mice exposed to NA via intraperitoneal injection at 200 mg/kg. These results directly validate the hypothesis that microsomal CYP enzymes in airway epithelial cells play a large role in causing injury to airway epithelia following exposure to NA via either inhalation or intraperitoneal route.
Collapse
Affiliation(s)
- Nataliia Kovalchuk
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona 85721.,Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York at Albany, Albany, New York 12201
| | - Qing-Yu Zhang
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona 85721.,Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York at Albany, Albany, New York 12201
| | - Laura Van Winkle
- Center for Health and the Environment and Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, UC Davis, Davis, California 95616
| | - Xinxin Ding
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona 85721
| |
Collapse
|
6
|
Yin J, Li F, Zhou Y, Mou M, Lu Y, Chen K, Xue J, Luo Y, Fu J, He X, Gao J, Zeng S, Yu L, Zhu F. INTEDE: interactome of drug-metabolizing enzymes. Nucleic Acids Res 2021; 49:D1233-D1243. [PMID: 33045737 PMCID: PMC7779056 DOI: 10.1093/nar/gkaa755] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/19/2020] [Accepted: 09/22/2020] [Indexed: 12/15/2022] Open
Abstract
Drug-metabolizing enzymes (DMEs) are critical determinant of drug safety and efficacy, and the interactome of DMEs has attracted extensive attention. There are 3 major interaction types in an interactome: microbiome-DME interaction (MICBIO), xenobiotics-DME interaction (XEOTIC) and host protein-DME interaction (HOSPPI). The interaction data of each type are essential for drug metabolism, and the collective consideration of multiple types has implication for the future practice of precision medicine. However, no database was designed to systematically provide the data of all types of DME interactions. Here, a database of the Interactome of Drug-Metabolizing Enzymes (INTEDE) was therefore constructed to offer these interaction data. First, 1047 unique DMEs (448 host and 599 microbial) were confirmed, for the first time, using their metabolizing drugs. Second, for these newly confirmed DMEs, all types of their interactions (3359 MICBIOs between 225 microbial species and 185 DMEs; 47 778 XEOTICs between 4150 xenobiotics and 501 DMEs; 7849 HOSPPIs between 565 human proteins and 566 DMEs) were comprehensively collected and then provided, which enabled the crosstalk analysis among multiple types. Because of the huge amount of accumulated data, the INTEDE made it possible to generalize key features for revealing disease etiology and optimizing clinical treatment. INTEDE is freely accessible at: https://idrblab.org/intede/.
Collapse
Affiliation(s)
- Jiayi Yin
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Fengcheng Li
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Ying Zhou
- The First Affiliated Hospital, Zhejiang University, Hangzhou 310000, China
| | - Minjie Mou
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yinjing Lu
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Kangli Chen
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jia Xue
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yongchao Luo
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jianbo Fu
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Xu He
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jianqing Gao
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
- Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University, Hangzhou 310018, China
| | - Su Zeng
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
- Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University, Hangzhou 310018, China
| | - Lushan Yu
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Feng Zhu
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
- Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University, Hangzhou 310018, China
| |
Collapse
|
7
|
Cohen SM, Zhongyu Y, Bus JS. Relevance of mouse lung tumors to human risk assessment. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2020; 23:214-241. [PMID: 32452303 DOI: 10.1080/10937404.2020.1763879] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Mouse lung is a common site for chemical tumorigenicity, but the relevance to human risk remains debated. Long-term bioassays need to be assessed for appropriateness of the dose, neither exceeding Maximum Tolerated Dose (MTD) nor Kinetically based Maximum Dose (KMD). An example of the KMD issue is 1,3-dichloropropene (1,3-D), which only produced an increased incidence of lung tumors at a dose exceeding the KMD. In addition, since mouse lung tumors are common (>1% incidence), the appropriate statistical significance is p < .01. Numerous differences exist for mouse lung and tumors compared to humans, including anatomy, respiratory rate, metabolism, tumor histogenesis, and metastatic frequency. The recent demonstration of the critical role of mouse lung specific Cyp2 F2 metabolism in mouse lung carcinogenicity including styrene or fluensulfone indicates that this tumor response is not qualitatively or quantitatively relevant to humans. For non-DNA reactive and non-mutagenic carcinogens, the mode of action involves direct mitogenicity such as for isoniazid, styrene, fluensulfone, permethrin or cytotoxicity with regeneration such as for naphthalene. However, the possibility of mixed mitogenic and cytotoxic modes of action cannot always be excluded. The numerous differences between mouse and human, combined with epidemiologic evidence of no increased cancer risk for several of these chemicals make the relevance of mouse lung tumors for human cancer risk dubious.
Collapse
Affiliation(s)
- Samuel M Cohen
- Havlik-Wall Professor of Oncology, University of Nebraska Medical Center , Omaha, NE, USA
- University of Nebraska Medical Center , Omaha, NE, USA
| | | | | |
Collapse
|