1
|
Yuan Q, Sallach JB, Rhodes G, Bach A, Crawford R, Li H, Johnston CT, Teppen BJ, Kaminski NE, Boyd SA. Natural organic matter does not diminish the mammalian bioavailability of 2,3,7,8-tetrachlorodibenzo-p-dioxin. CHEMOSPHERE 2021; 264:128420. [PMID: 33032214 PMCID: PMC7749823 DOI: 10.1016/j.chemosphere.2020.128420] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 08/21/2020] [Accepted: 09/20/2020] [Indexed: 06/11/2023]
Abstract
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a toxic and persistent organic pollutant found in soils and sediments. It has been linked to several adverse health outcomes in humans and wildlife, including suppression of the immune system. TCDD is strongly sorbed to soils/sediments due to its extremely low water solubility. Presently, the bioavailability of soil/sediment-sorbed TCDD to mammals is not completely understood. Our previous studies demonstrated that TCDD adsorbed to representative inorganic geosorbents (i.e. porous silica and smectite clay) exhibited the same bioavailability to mice as TCDD dissolved in corn oil, whereas sequestration by activated carbons eliminated TCDD bioavailability. In this study, we evaluated the effects of amorphous natural organic matter (NOM), primarily in the form of aquatic humic and fulvic acids, on the mouse bioavailability of TCDD. An aqueous suspension of TCDD mixed with NOM was administered to mice via oral gavage. The relative bioavailability of TCDD was assessed by two sensitive aryl hydrocarbon receptor-mediated responses in mice: 1) hepatic induction of cyp1A1 mRNA; and 2) suppression of immunoglobulin M (IgM) antibody-forming cell (AFC) response which is an indicator of immunotoxicity. Hepatic induction of cyp1A1 mRNA and suppression of IgM AFC induced by TCDD were similar in the NOM-sorbed form and dissolved in corn oil, revealing no loss of bioavailability when associated with NOM. Hence, NOM-associated TCDD is as capable of suppressing humoral immunity in mice as TCDD dissolved in corn oil, indicating that NOM-sorbed TCDD is likely to fully retain its bioavailability to mammals and, by inference, humans.
Collapse
Affiliation(s)
- Qi Yuan
- Department of Microbiology and Immunology, Creighton University, Omaha, NE, 68178, USA
| | - J Brett Sallach
- Department of Environment and Geography, University of York, Heslington, York, YO10 5NG, United Kingdom.
| | - Geoff Rhodes
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI, 48824, USA
| | - Anthony Bach
- Institute for Integrative Toxicology, Michigan State University, East Lansing, MI, 48824, USA
| | - Robert Crawford
- Institute for Integrative Toxicology, Michigan State University, East Lansing, MI, 48824, USA
| | - Hui Li
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI, 48824, USA
| | - Cliff T Johnston
- Crop, Soil, and Environmental Science, Purdue University, West Lafayette, IN, 47907, USA
| | - Brian J Teppen
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI, 48824, USA
| | - Norbert E Kaminski
- Institute for Integrative Toxicology, Michigan State University, East Lansing, MI, 48824, USA; Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, 48824, USA; Center for Research on Ingredient Safety, Michigan State University, East Lansing, MI, 48824, USA
| | - Stephen A Boyd
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI, 48824, USA
| |
Collapse
|
2
|
Yang X, Ku T, Sun Z, Liu QS, Yin N, Zhou Q, Faiola F, Liao C, Jiang G. Assessment of the carcinogenic effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin using mouse embryonic stem cells to form teratoma in vivo. Toxicol Lett 2019; 312:139-147. [PMID: 31082521 DOI: 10.1016/j.toxlet.2019.05.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 03/21/2019] [Accepted: 05/09/2019] [Indexed: 12/26/2022]
Abstract
As the most toxic dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has gained lots of concerns, due to its diverse deleterious effects. However, the knowledge on carcinogenic risk of TCDD during early stage of development remains scarce. The in vivo teratoma formation model based on the transplantation of embryonic stem cells (ESCs) in immunodeficient mice is appealing for studying pluripotency and tumorigenicity in developmental biology, and also shows promise in environmental toxicology, especially in carcinogenesis researches. In this study, the malignant transformation of mouse embryonic stem cells (mESCs) pretreated with TCDD was investigated during their in vivo differentiation using teratoma formation model. Based on characterization of the pluripotency and differentiation capabilities of mESCs, evil changes in teratomas derived from TCDD-exposed mESCs were systematically studied. The results showed that TCDD significantly up-regulated CYP1A1 transcriptional levels in mESCs, elevated the incidence of malignant change in mESC-derived teratomas, and caused indefinite proliferation capabilities in sequential cultures of tumor tissues. The findings suggested that TCDD could exert carcinogenic effect on mESCs during their differentiation into teratoma in vivo, and more attention should be paid to the adverse health effects of this chemical during gestation or early developmental period.
Collapse
Affiliation(s)
- Xiaoxi Yang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Tingting Ku
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; College of Environment and Resource, Research Center of Environment and Health, Shanxi University, Taiyuan, 030006, China
| | - Zhendong Sun
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qian S Liu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Nuoya Yin
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Qunfang Zhou
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China; Institute of Environment and Health, Jianghan University, Wuhan, 430056, China.
| | - Francesco Faiola
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Chunyang Liao
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Guibin Jiang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China
| |
Collapse
|
3
|
Aida-Yasuoka K, Nishimura N, Fujisawa N, Endo N, Narumiya S, Tohyama C. The role of prostaglandin E 2 receptor EP1 in 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced neonatal hydronephrosis in mice. Toxicology 2019; 415:10-17. [PMID: 30641090 DOI: 10.1016/j.tox.2019.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 01/08/2019] [Accepted: 01/09/2019] [Indexed: 10/27/2022]
Abstract
Prostaglandin E2 (PGE2) is a critical factor in the pathogenesis of dioxin-induced neonatal hydronephrosis. Since the PGE2 receptor has four subtypes, EP1 - EP4, this study was aimed to challenge the hypothesis that at least one of the four subtypes is responsible for the pathogenesis of dioxin-induced hydronephrosis. To this end, we used mouse pups, with a C57BL/6 J background, genetically lacking EP1, EP2, or EP3, and wild-type pups in whom EP4 was suppressed by administering ONO-AE3-208 (ONO), an EP4 antagonist, from postnatal day 1 (PND 1) to PND 13. To expose the pups to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) via lactation, the dams were administered TCDD at an oral dose of 20 μg/kg on PND 1. The pups' urine and kidneys were collected on PND 14 for urinalysis and histological examination, respectively. We found that the incidence of hydronephrosis was 80% in the EP1+/+ group, but was markedly reduced to 28.6% in the EP1-/- group despite the fact that PGE2 concentration in the urine was similarly increased in the both groups. In contrast, the incidence of hydronephrosis was 80% and 100% in the EP2+/+ and EP2-/-groups, respectively, and 88.9% and 100% in the EP3+/+ and EP3-/- groups, respectively. With regard to EP4, the incidence of hydronephrosis in vehicle (saline)-treated groups and ONO-treated was 88.9% and 100%, respectively. Therefore, we concluded that among PGE2 receptor subtypes, EP1 plays a predominant role in the onset of TCDD-induced neonatal hydronephrosis in mouse pups.
Collapse
Affiliation(s)
- Keiko Aida-Yasuoka
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Noriko Nishimura
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Nozomi Fujisawa
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Nozomi Endo
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Shuh Narumiya
- Department of Drug Discovery Medicine, Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan
| | - Chiharu Tohyama
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan; Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan.
| |
Collapse
|
4
|
Fujisawa N, Yoshioka W, Yanagisawa H, Tohyama C. Significance of AHR nuclear translocation sequence in 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced cPLA 2α activation and hydronephrosis. Arch Toxicol 2019; 93:1255-1264. [PMID: 30790002 DOI: 10.1007/s00204-019-02414-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 02/14/2019] [Indexed: 12/13/2022]
Abstract
The aryl hydrocarbon receptor (AHR) plays a major role in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced toxicity phenotypes. TCDD bound to AHR elicits both genomic action in which target genes are transcriptionally upregulated and nongenomic action in which cytosolic phospholipase A2α (cPLA2α) is rapidly activated. However, how either of these actions, separately or in combination, induces toxicity phenotypes is largely unknown. In this study, we used AHRnls/nls mice as a model in which AHR was mutated to lack nuclear translocation sequence (NLS), and AHRd/- mice as the corresponding control. Using this model, we studied TCDD-induced alterations in cPLA2α activation and related factors because of the pivotal roles of cPLA2α both in AHR's nongenomic action and in regulation of causative genes of TCDD-induced hydronephrosis. Dams were orally administered TCDD at a dose of 300 µg/kg body weight on postnatal day 1, and pups subsequently exposed to TCDD via milk were examined for gene expression on PND 7 and for histological changes on PND 14. The activation of the AHR genomic action and hydronephrosis onset were observed in the control group but not in the AHRnls/nls group. An ex vivo experiment using peritoneal macrophages exposed to 100 nM TCDD resulted in rapid activation of cPLA2α, an indicator of the nongenomic action, only in the control group but not in the AHRnls/nls group. These results indicated that an NLS is required for the AHR's genomic and nongenomic actions.
Collapse
Affiliation(s)
- Nozomi Fujisawa
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Wataru Yoshioka
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan. .,Department of Public Health and Environmental Medicine, The Jikei University School of Medicine, Tokyo, 105-8461, Japan.
| | - Hiroyuki Yanagisawa
- Department of Public Health and Environmental Medicine, The Jikei University School of Medicine, Tokyo, 105-8461, Japan
| | - Chiharu Tohyama
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan. .,Faculty of Medicine, University of Tsukuba, Tsukuba, 305-8575, Japan.
| |
Collapse
|
5
|
Yoshioka W, Tohyama C. Mechanisms of Developmental Toxicity of Dioxins and Related Compounds. Int J Mol Sci 2019; 20:E617. [PMID: 30708991 PMCID: PMC6387164 DOI: 10.3390/ijms20030617] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 01/29/2019] [Accepted: 01/30/2019] [Indexed: 12/20/2022] Open
Abstract
Dioxins and related compounds induce morphological abnormalities in developing animals in an aryl hydrocarbon receptor (AhR)-dependent manner. Here we review the studies in which 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is used as a prototypical compound to elucidate the pathogenesis of morphological abnormalities. TCDD-induced cleft palate in fetal mice involves a delay in palatogenesis and dissociation of fused palate shelves. TCDD-induced hydronephrosis, once considered to be caused by the anatomical obstruction of the ureter, is now separated into TCDD-induced obstructive and non-obstructive hydronephrosis, which develops during fetal and neonatal periods, respectively. In the latter, a prostaglandin E₂ synthesis pathway and urine concentration system are involved. TCDD-induced abnormal development of prostate involves agenesis of the ventral lobe. A suggested mechanism is that AhR activation in the urogenital sinus mesenchyme by TCDD modulates the wingless-type MMTV integration site family (WNT)/β-catenin signaling cascade to interfere with budding from urogenital sinus epithelium. TCDD exposure to zebrafish embryos induces loss of epicardium progenitor cells and heart malformation. AHR2-dependent downregulation of Sox9b expression in cardiomyocytes is a suggested underlying mechanism. TCDD-induced craniofacial malformation in zebrafish is considered to result from the AHR2-dependent reduction in SRY-box 9b (SOX9b), probably partly via the noncoding RNA slincR, resulting in the underdevelopment of chondrocytes and cartilage.
Collapse
Affiliation(s)
- Wataru Yoshioka
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan.
| | - Chiharu Tohyama
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan.
| |
Collapse
|
6
|
Fujisawa N, Yoshioka W, Yanagisawa H, Tohyama C. Roles of cytosolic phospholipase A 2α in reproductive and systemic toxicities in 2,3,7,8-tetrachlorodibenzo-p-dioxin-exposed mice. Arch Toxicol 2017; 92:789-801. [PMID: 29043426 PMCID: PMC5818604 DOI: 10.1007/s00204-017-2081-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 09/25/2017] [Indexed: 12/01/2022]
Abstract
Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces a variety of toxicities upon binding of TCDD to aryl hydrocarbon receptor. Although this binding upregulates the synthesis of prostaglandins and their related lipid mediators via cytosolic phospholipase A2α (cPLA2α), toxicological significance of this signaling pathway remains elusive. Herein, we investigated the roles of cPLA2α in TCDD toxicities using cPLA2α-null mice. In a first set of experiments, pregnant mice were orally administered TCDD at a dose of 40 μg/kg on gestation day (GD) 12.5, and fetuses were collected on GD 18 for subsequent analyses. The number of live male fetuses of cPLA2α-null type was significantly less than that of wild-type in TCDD-exposed litters. TCDD-induced hydronephrosis was more severe in wild-type fetuses than in cPLA2α-null fetuses regardless of sex, and kidney expression levels of the inflammatory cytokines interleukin-1β and tumor necrosis factor-α were increased in a cPLA2α-dependent manner in TCDD-exposed fetuses. In a second set of experiments, following intraperitoneal administration of TCDD at 50 μg/kg, body weight of the male adult mice was decreased within 2 days in wild-type mice but was not changed in cPLA2α-null mice. In addition, TCDD-induced lipid accumulation in the livers of cPLA2α-null mice was at an intermediate level compared with TCDD-exposed wild-type and vehicle-control mice. In conclusion, the present results show that cPLA2α is involved in TCDD-induced body weight loss, lipid accumulation in the liver, fetal hydronephrosis, and cytokine gene expression, and that the molecular basis of TCDD toxicity differs considerably between target tissues and life stages.
Collapse
Affiliation(s)
- Nozomi Fujisawa
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Wataru Yoshioka
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan. .,Department of Public Health and Environmental Medicine, The Jikei University School of Medicine, Tokyo, 105-8461, Japan.
| | - Hiroyuki Yanagisawa
- Department of Public Health and Environmental Medicine, The Jikei University School of Medicine, Tokyo, 105-8461, Japan
| | - Chiharu Tohyama
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan. .,Department of Anatomy and Embryology, Faculty of Medicine, University of Tsukuba, Tsukuba, 305-8575, Japan.
| |
Collapse
|
7
|
Yoshioka W, Kawaguchi T, Nishimura N, Akagi T, Fujisawa N, Yanagisawa H, Matsumura F, Tohyama C. Polyuria-associated hydronephrosis induced by xenobiotic chemical exposure in mice. Am J Physiol Renal Physiol 2016; 311:F752-F762. [DOI: 10.1152/ajprenal.00001.2016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 07/16/2016] [Indexed: 12/19/2022] Open
Abstract
Hydronephrosis is a commonly found disease state characterized by the dilation of renal calices and pelvis, resulting in the loss of kidney function in the severest cases. A generally accepted etiology of hydronephrosis involves the obstruction of urine flow along the urinary tract. In the recent years, we have developed a mouse model of hydronephrosis induced by lactational exposure to dioxin and demonstrated a lack of anatomical obstruction in this model. We also showed that prostaglandin E2 synthesis system plays a critical role in the onset of hydronephrosis. In the present study, we found that neonatal hydronephrosis was not likely to be associated with functional obstruction (impaired peristalsis) but was found to be associated with polyuria and low urine osmolality with the downregulation of proteins involved in the urine concentrating process. The administration of an antidiuretic hormone analog to the dioxin-exposed pups not only suppressed the increased urine output but also decreased the incidence and severity of hydronephrosis. In contrast to the case in pups, administration of dioxin to adult mice failed to induce polyuria and upregulation of prostaglandin E2 synthesis system, and the adult mice were resistant to develop hydronephrosis. These findings suggest the possibility that polyuria could induce hydronephrosis in the absence of anatomical or functional obstruction of the ureter. It is concluded that the present animal model provides a unique example of polyuria-associated type of hydronephrosis, suggesting a need to redefine this disease state.
Collapse
Affiliation(s)
- Wataru Yoshioka
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Public Health and Environmental Medicine, The Jikei University School of Medicine, Tokyo, Japan
| | - Tatsuya Kawaguchi
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Noriko Nishimura
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Toshiya Akagi
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Nozomi Fujisawa
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hiroyuki Yanagisawa
- Department of Public Health and Environmental Medicine, The Jikei University School of Medicine, Tokyo, Japan
| | - Fumio Matsumura
- Department of Environmental Toxicology and Center for Environmental Health Sciences, University of California, Davis, California; and
| | - Chiharu Tohyama
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| |
Collapse
|
8
|
Joiakim A, Mathieu PA, Shelp C, Boerner J, Reiners JJ. Epidermal Growth Factor Receptor Kinase Inhibitors Synergize with TCDD to Induce CYP1A1/1A2 in Human Breast Epithelial MCF10A Cells. Drug Metab Dispos 2016; 44:665-71. [PMID: 26953171 PMCID: PMC11024934 DOI: 10.1124/dmd.115.066274] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 03/03/2016] [Indexed: 04/20/2024] Open
Abstract
CYP1A1 and CYP1A2 are transcriptionally activated in the human normal breast epithelial cell line MCF10A following exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Shifting MCF10A cultures to medium deficient in serum and epidermal growth factor (EGF) caused rapid reductions in the activated (i.e., phosphorylated) forms of extracellular regulated kinases (ERKs) and the epidermal growth factor receptor (EGFR). Shifting to serum/EGF-deficient medium also enhanced TCDD-mediated induction of cytochrome P450 (CYP)1A1 Treatment of cells cultured in complete medium with the EGFR inhibitors gefitinib (Iressa), AG1478, and CI-1033 resulted in concentration-dependent reductions of active EGFR and ERKs, and increased CYP1A1 mRNA content ∼3- to 18-fold above basal level. EGFR inhibitors synergized with TCDD and resulted in transient CYP1A1 and CYP1A2 mRNA accumulations ∼8-fold greater (maximum at 5 hours) than that achieved with only TCDD. AG1478, gefitinib, and TCDD individually induced small increases (∼1.2- to 2.5-fold) in CYP1A1 protein content but did not cause additive or synergistic accumulations of CYP1A1 protein when used in combination. The mitogen-activated protein kinase kinase inhibitor PD184352 inhibited ERK and EGFR activation in a concentration-dependent fashion without causing CYP1A1 mRNA accumulation. However, cotreatment with PD184352 potentiated TCDD-mediated CYP1A1 induction. TCDD-mediated induction of CYP1A1 in MCF7-TET on-EGFR cells, a MCF7 variant in which EGFR expression can be controlled, was not affected by the activity status of EGFR or ERKs. Hence, EGFR signaling mutes both basal and ligand-induced expression of two aryl hydrocarbon receptor-responsive P450s in MCF10A cultures. However, these effects are cell context-dependent. Furthermore, CYP1A1 mRNA and protein abundance are not closely coupled in MCF10A cultures.
Collapse
Affiliation(s)
- Aby Joiakim
- Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan (A.J., P.A.M., J.J.R.); Department of Pharmacology (C.S., J.J.R.) and Department of Oncology (J.B.), Wayne State University School of Medicine, Karmanos Cancer Institute, Detroit, Michigan
| | - Patricia A Mathieu
- Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan (A.J., P.A.M., J.J.R.); Department of Pharmacology (C.S., J.J.R.) and Department of Oncology (J.B.), Wayne State University School of Medicine, Karmanos Cancer Institute, Detroit, Michigan
| | - Catherine Shelp
- Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan (A.J., P.A.M., J.J.R.); Department of Pharmacology (C.S., J.J.R.) and Department of Oncology (J.B.), Wayne State University School of Medicine, Karmanos Cancer Institute, Detroit, Michigan
| | - Julie Boerner
- Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan (A.J., P.A.M., J.J.R.); Department of Pharmacology (C.S., J.J.R.) and Department of Oncology (J.B.), Wayne State University School of Medicine, Karmanos Cancer Institute, Detroit, Michigan
| | - John J Reiners
- Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan (A.J., P.A.M., J.J.R.); Department of Pharmacology (C.S., J.J.R.) and Department of Oncology (J.B.), Wayne State University School of Medicine, Karmanos Cancer Institute, Detroit, Michigan
| |
Collapse
|
9
|
Buser MC, Pohl HR. Windows of Sensitivity to Toxic Chemicals in the Development of Cleft Palates. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2015; 18:242-57. [PMID: 26503716 PMCID: PMC5642923 DOI: 10.1080/10937404.2015.1068719] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Cleft lip and cleft palate are among the most common birth defects worldwide. There is a genetic component to the development of these malformations, as well as evidence that environmental exposures and prescription drug use may exacerbate or even produce these manifestations. Thus, it is important to understand the underlying mechanisms and when these exposures affect development of the growing fetus. The purpose of this investigation was to critically review the available literature related to orofacial cleft formation following chemical exposure and identify specific time frames for windows of sensitivity. Further, an aim was to evaluate the potential for predicting effects in humans based on animal studies. Evidence indicates that chemical causes of cleft palate development are due to dose and timing of exposure, susceptibility of the species (i.e., the genetic makeup), and mechanism of action. Several studies demonstrated that dose is a crucial factor; however, some investigators argued that even more important than dose was timing of exposure. Data show that the window of sensitivity to environmental teratogens in the development of cleft palates is quite narrow and follows closely the window of palatogenesis in the fetus of any given species.
Collapse
Affiliation(s)
- M C Buser
- a Agency for Toxic Substances and Disease Registry , U.S. Department of Health and Human Services , Atlanta , Georgia , USA
| | - H R Pohl
- a Agency for Toxic Substances and Disease Registry , U.S. Department of Health and Human Services , Atlanta , Georgia , USA
| |
Collapse
|
10
|
Hong JS, Park MK, Kim MS, Lim JH, Park GJ, Maeng EH, Shin JH, Kim MK, Jeong J, Park JA, Kim JC, Shin HC. Prenatal development toxicity study of zinc oxide nanoparticles in rats. Int J Nanomedicine 2014; 9 Suppl 2:159-71. [PMID: 25565834 PMCID: PMC4279776 DOI: 10.2147/ijn.s57932] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
This study investigated the potential adverse effects of zinc oxide nanoparticles ([ZnO(SM20(+)) NPs] zinc oxide nanoparticles, positively charged, 20 nm) on pregnant dams and embryo-fetal development after maternal exposure over the period of gestational days 5-19 with Sprague-Dawley rats. ZnO(SM20(+)) NPs were administered to pregnant rats by gavage at 0, 100, 200, and 400 mg/kg/day. All dams were subjected to a cesarean section on gestational day 20, and all of the fetuses were examined for external, visceral, and skeletal alterations. Toxicity in the dams manifested as significantly decreased body weight after administration of 400 mg/kg/day NPs; reduced food consumption after administration of 200 and 400 mg/kg/day NPs; and decreased liver weight and increased adrenal glands weight after administration of 400 mg/kg/day NPs. However, no treatment-related difference in: number of corpora lutea; number of implantation sites; implantation rate (%); resorption; dead fetuses; litter size; fetal deaths and placental weights; and sex ratio were observed between the groups. On the other hand, significant decreases between treatment groups and controls were seen for fetal weights after administration of 400 mg/kg/day NPs. Morphological examinations of the fetuses demonstrated significant differences in incidences of abnormalities in the group administered 400mg/kg/day. Meanwhile, no significant difference was found in the Zn content of fetal tissue between the control and high-dose groups. These results showed that oral doses for the study with 15-days repeated of ZnO(SM20(+)) NPs were maternotoxic in the 200 mg/kg/day group, and embryotoxic in the 400 mg/kg/day group.
Collapse
Affiliation(s)
- Jeong-Sup Hong
- Health Care Research Laboratory, Korea Testing and Research Institute, Gimpo, South Korea ; College of Veterinary Medicine, Konkuk University, Seoul, South Korea
| | - Myeong-Kyu Park
- Health Care Research Laboratory, Korea Testing and Research Institute, Gimpo, South Korea
| | - Min-Seok Kim
- Health Care Research Laboratory, Korea Testing and Research Institute, Gimpo, South Korea
| | - Jeong-Hyeon Lim
- Health Care Research Laboratory, Korea Testing and Research Institute, Gimpo, South Korea
| | - Gil-Jong Park
- Health Care Research Laboratory, Korea Testing and Research Institute, Gimpo, South Korea
| | - Eun-Ho Maeng
- Health Care Research Laboratory, Korea Testing and Research Institute, Gimpo, South Korea
| | - Jae-Ho Shin
- Department of Biomedical Laboratory Science, Eulji University, Seongnam-si, South Korea
| | - Meyoung-Kon Kim
- Department of Biochemistry and Molecular Biology, Korea University Medical School and College, Seoul, South Korea
| | - Jayoung Jeong
- Toxicological Research Division, National Institute of Food and Drug Safety Evaluation, Chungcheongbuk-do, South Korea
| | - Jin-A Park
- College of Veterinary Medicine, Konkuk University, Seoul, South Korea
| | - Jong-Choon Kim
- College of Veterinary Medicine, Chonnam National University, Gwangju, South Korea
| | - Ho-Chul Shin
- College of Veterinary Medicine, Konkuk University, Seoul, South Korea
| |
Collapse
|
11
|
Hong JS, Park MK, Kim MS, Lim JH, Park GJ, Maeng EH, Shin JH, Kim YR, Kim MK, Lee JK, Park JA, Kim JC, Shin HC. Effect of zinc oxide nanoparticles on dams and embryo-fetal development in rats. Int J Nanomedicine 2014; 9 Suppl 2:145-57. [PMID: 25565833 PMCID: PMC4279755 DOI: 10.2147/ijn.s57931] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
This study investigated the potential adverse effects of zinc oxide nanoparticles (ZnOSM20[−] NPs; negatively charged, 20 nm) on pregnant dams and embryo–fetal development after maternal exposure over the period of gestational days 5–19 with Sprague Dawley rats. ZnOSM20(−) NPs were administered to pregnant rats by gavage at 0 mg/kg/day, 100 mg/kg/day, 200 mg/kg/day, and 400 mg/kg/day. All dams were subjected to caesarean section on gestational day 20, and all the fetuses were examined for external, visceral, and skeletal alterations. Toxicity in the dams manifested as significantly decreased body weight at 400 mg/kg/day and decreased liver weight, and increased adrenal glands weight at 200 mg/kg/day and 400 mg/kg/day. However, no treatment-related difference in the number of corpora lutea, the number of implantation sites, the implantation rate (%), resorption, dead fetuses, litter size, fetal deaths, fetal and placental weights, and sex ratio were observed between the groups. Morphological examinations of the fetuses demonstrated no significant difference in the incidences of abnormalities between the groups. No significant difference was found in the Zn content of fetal tissue between the control and high-dose groups. These results showed that a 15-day repeated oral dose of ZnOSM20(−) was minimally maternotoxic at dose of 200 mg/kg/day and 400 mg/kg/day.
Collapse
Affiliation(s)
- Jeong-Sup Hong
- Health Care Research Laboratory, Korea Testing and Research Institute, Gimpo, Korea ; College of Veterinary Medicine, Konkuk University, Seoul, Korea
| | - Myeong-Kyu Park
- Health Care Research Laboratory, Korea Testing and Research Institute, Gimpo, Korea
| | - Min-Seok Kim
- Health Care Research Laboratory, Korea Testing and Research Institute, Gimpo, Korea
| | - Jeong-Hyeon Lim
- Health Care Research Laboratory, Korea Testing and Research Institute, Gimpo, Korea
| | - Gil-Jong Park
- Health Care Research Laboratory, Korea Testing and Research Institute, Gimpo, Korea
| | - Eun-Ho Maeng
- Health Care Research Laboratory, Korea Testing and Research Institute, Gimpo, Korea
| | - Jae-Ho Shin
- Department of Biomedical Laboratory Science, Eulji University, Seongnam-si, Korea
| | - Yu-Ri Kim
- Department of Biochemistry and Molecular Biology, Korea University Medical School and College, Seoul, Korea
| | - Meyoung-Kon Kim
- Department of Biochemistry and Molecular Biology, Korea University Medical School and College, Seoul, Korea
| | - Jong-Kwon Lee
- Toxicological Research Division, National Institute of Food and Drug Safety Evaluation, Chungcheongbuk-do, Gwangju, Korea
| | - Jin-A Park
- College of Veterinary Medicine, Konkuk University, Seoul, Korea
| | - Jong-Choon Kim
- College of Veterinary Medicine, Chonnam National University, Gwangju, Korea
| | - Ho-Chul Shin
- College of Veterinary Medicine, Konkuk University, Seoul, Korea
| |
Collapse
|
12
|
Aida-Yasuoka K, Yoshioka W, Kawaguchi T, Ohsako S, Tohyama C. A mouse strain less responsive to dioxin-induced prostaglandin E2 synthesis is resistant to the onset of neonatal hydronephrosis. Toxicol Sci 2014; 141:465-74. [PMID: 25015655 DOI: 10.1093/toxsci/kfu142] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Dioxin is a ubiquitous environmental pollutant that induces toxicity when bound to the aryl hydrocarbon receptor (AhR). Significant differences in susceptibility of mouse strains to dioxin toxicity are largely accounted for by the dissociation constant of binding to dioxins of AhR subtypes encoded by different alleles. We showed that cyclooxygenase-2 (COX-2) and microsomal prostaglandin E synthase-1 (mPGES-1), components of a prostanoid synthesis pathway, play essential roles in the onset of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced hydronephrosis of neonatal mice. Although C57BL/6J and BALB/cA mice harbor AhR receptors highly responsive to TCDD, they were found by chance to differ significantly in the incidence of TCDD-induced hydronephrosis. Therefore, the goal of the present study was to determine the molecular basis of this difference in susceptibility to TCDD toxicity. For this purpose, we administered C57BL/6J and BALB/cA dams' TCDD at an oral dose of 15 or 80 μg/kg on postnatal day (PND) 1 to expose pups to TCDD via lactation, and the pups' kidneys were collected on PND 7. The incidence of hydronephrosis in C57BL/6J pups (64%) was greater than in BALB/cA pups (0%, p < 0.05), despite similarly increased levels of COX-2 mRNA. The incidence of hydronephrosis in these mouse strains paralleled the levels of renal mPGES-1 mRNA and early growth response 1 (Egr-1) that modulates mPGES-1 gene expression, as well as PGE2 concentrations in urine. Although these mouse strains possess AhR alleles tightly bound to TCDD, their difference in incidence and severity of hydronephrosis can be explained, in part, by differences in the expression of mPGES-1 and Egr-1.
Collapse
Affiliation(s)
- Keiko Aida-Yasuoka
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Wataru Yoshioka
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan Department of Pathophysiology, Tokyo University of Pharmacy and Life Sciences, Tokyo 192-0392, Japan
| | - Tatsuya Kawaguchi
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Seiichiroh Ohsako
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Chiharu Tohyama
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| |
Collapse
|
13
|
Predominant role of cytosolic phospholipase A2α in dioxin-induced neonatal hydronephrosis in mice. Sci Rep 2014; 4:4042. [PMID: 24509627 PMCID: PMC3918923 DOI: 10.1038/srep04042] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Accepted: 01/24/2014] [Indexed: 11/17/2022] Open
Abstract
Hydronephrosis is a common disease characterized by dilation of the renal pelvis and calices, resulting in loss of kidney function in the most severe cases. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) induces nonobstructive hydronephrosis in mouse neonates through upregulation of prostaglandin E2 (PGE2) synthesis pathway consisting of cyclooxygenase-2 (COX-2) and microsomal prostaglandin E synthase-1 (mPGES-1) by a yet unknown mechanism. We here studied possible involvement of cytosolic phospholipase A2α (cPLA2α) in this mechanism. To this end, we used a cPLA2α-null mouse model and found that cPLA2α has a significant role in the upregulation of the PGE2 synthesis pathway through a noncanonical pathway of aryl hydrocarbon receptor. This study is the first to demonstrate the predominant role of cPLA2α in hydronephrosis. Elucidation of the pathway leading to the onset of hydronephrosis using the TCDD-exposed mouse model will deepen our understanding of the molecular basis of nonobstructive hydronephrosis in humans.
Collapse
|
14
|
Zhang J, Lanham KA, Heideman W, Peterson RE, Li L. Statistically enhanced spectral counting approach to TCDD cardiac toxicity in the adult zebrafish heart. J Proteome Res 2013; 12:3093-103. [PMID: 23682714 PMCID: PMC3740750 DOI: 10.1021/pr400312u] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a persistent environmental pollutant and teratogen that produces cardiac toxicity in the developing zebrafish. Here we adopted a label free quantitative proteomic approach based on normalized spectral abundance factor (NSAF) to investigate the disturbance of the cardiac proteome induced by TCDD in the adult zebrafish heart. The protein expression level changes between heart samples from TCDD-treated and control zebrafish were systematically evaluated by a large scale MudPIT analysis, which incorporated triplicate analyses for both control and TCDD-exposed heart proteomic samples to overcome the data-dependent variation in shotgun proteomic experiments and obtain a statistically significant protein data set with improved quantification confidence. A total of 519 and 443 proteins were identified in hearts collected from control and TCDD-treated zebrafish, respectively, among which 106 proteins showed statistically significant expression changes. After correcting for the experimental variation between replicate analyses by statistical evaluation, 55 proteins exhibited NSAF ratios above 2 and 43 proteins displayed NSAF ratios smaller than 0.5, with statistical significance by t test (p < 0.05). The proteins identified as altered by TCDD encompass a wide range of biological functions including calcium handling, myocardium cell architecture, energy production and metabolism, mitochondrial homeostasis, and stress response. Collectively, our results indicate that TCDD exposure alters the adult zebrafish heart in a way that could result in cardiac hypertrophy and heart failure and suggests a potential mechanism for the diastolic dysfunction observed in TCDD-exposed embryos.
Collapse
Affiliation(s)
- Jiang Zhang
- School of Pharmacy, University of Wisconsin - Madison, WI, USA
| | - Kevin A Lanham
- Department of Biomolecular Chemistry, University of Wisconsin - Madison, WI, USA
| | - Warren Heideman
- School of Pharmacy, University of Wisconsin - Madison, WI, USA
| | | | - Lingjun Li
- School of Pharmacy, University of Wisconsin - Madison, WI, USA
- Department of Chemistry, University of Wisconsin - Madison, WI, USA
| |
Collapse
|
15
|
Yoshioka W, Aida-Yasuoka K, Fujisawa N, Kawaguchi T, Ohsako S, Hara S, Uematsu S, Akira S, Tohyama C. Critical Role of Microsomal Prostaglandin E Synthase-1 in the Hydronephrosis Caused by Lactational Exposure to Dioxin in Mice. Toxicol Sci 2012; 127:547-54. [DOI: 10.1093/toxsci/kfs115] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
16
|
del Río A, Barrio M, Murillo J, Maldonado E, López-Gordillo Y, Martínez-Sanz E, Martínez M, Martínez-Álvarez C. Analysis of the Presence of Cell Proliferation-Related Molecules in the Tgf-β 3 Null Mutant Mouse Palate Reveals Misexpression of EGF and Msx-1. Cells Tissues Organs 2011; 193:135-50. [DOI: 10.1159/000319970] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2010] [Indexed: 02/03/2023] Open
|
17
|
Abbott BD. The etiology of cleft palate: a 50-year search for mechanistic and molecular understanding. ACTA ACUST UNITED AC 2010; 89:266-74. [PMID: 20602452 DOI: 10.1002/bdrb.20252] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Dates of special, historical significance, such as the 50th anniversary of the founding of the Teratology Society, prompt a desire to pause and look back and contemplate where we began, how far we have come, and consider the future for our scientific endeavors. The study of the etiology of cleft palate extends many years into the past and was a subject of interest to many of the founding members of the Teratology Society. This research area was intensively pursued and spawned a vast portfolio of published research. This article will look back at the state of the science around the time of the founding of the Teratology Society, in the 1950s and 1960s, and track the emergence and pursuit of an interest in an etiology for cleft palate involving failure of palatal fusion. Studies of medial epithelial cell fate and induction of cleft palate by interference with adhesion or fusion span the period from the 1960s to the present time. Teratology Society members have been and continue to be key players in cleft palate research. In this retrospective article, seminal research published by Teratology Society members will serve as a platform to launch the discussion of the emergence of our current understanding of medial epithelial cell differentiation and fate and the potential for these processes to be targets of teratogenic action.
Collapse
Affiliation(s)
- Barbara D Abbott
- Developmental Biology Branch, Toxicity Assessment Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA.
| |
Collapse
|
18
|
Olivero-Verbel J, Cabarcas-Montalvo M, Ortega-Zúñiga C. Theoretical targets for TCDD: a bioinformatics approach. CHEMOSPHERE 2010; 80:1160-1166. [PMID: 20605043 DOI: 10.1016/j.chemosphere.2010.06.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Revised: 05/19/2010] [Accepted: 06/07/2010] [Indexed: 05/29/2023]
Abstract
Dioxins are a group of highly toxic molecules that exert their toxicity through the activation of the aryl hydrocarbon receptor (AhR). The most important agonist of the AhR, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a highly toxic compound. Although most of the effects related to TCDD exposure have been linked to the activation of AhR, the objective of this work was to use a bioinformatics approach to identify possible new targets for TCDD. The Target Fishing Docking (TarFisDock) Server was used to find target proteins for TCDD. This virtual screening allowed the identification of binding sites with high affinity for TCDD in diverse proteins, such as metallopeptidases 8 and 3, oxidosqualene cyclase, and myeloperoxidase. Some of these proteins are well known for their biochemical role in some pathological effects of dioxin exposure, including endometriosis, diabetes, inflammation and liver damage. These results suggest that TCDD could also be interacting with cellular targets though AhR-independent pathways.
Collapse
Affiliation(s)
- Jesús Olivero-Verbel
- Environmental and Computational Chemistry Group, University of Cartagena, Cartagena, Colombia.
| | | | | |
Collapse
|
19
|
Li CH, Bing Shi, Wei He, Tian Meng. Is it possible to antagonize 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin- induced cleft palate by prenatal administration of folic acid? An experimental study. Toxicol Ind Health 2010; 26:281-6. [PMID: 20305052 DOI: 10.1177/0748233710364964] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) can cause a high percentage of cleft palate in fetuses when administered during organogenesis in certain strains of mice including C57BL/6J. In this study, folic acid (FA) was tested for antiteratogenic effects on TCDD-induced cleft palate in fetal mice. The pregnant C57BL/6J mice were dosed with 24 µg TCDD/kg and/or 5 mg, 10 mg, 20 mg, 40 mg FA/kg body weight on gestation day (GD) 10. The control group mice received 50 mL sesame oil/kg body weight on GD10. The mice were sacrificed on GD12.5, GD13.5, GD14.5, GD15.5, and GD16.5. The harvested embryos were examined to detect the incidence of cleft palate and the developing palatal shelves on different phases were investigated morphologically and histologically among different groups. Total frequency of clefts was 55.56% in TCDD group and 17.50% (5 mg), 42.85% (10 mg), 42.10% (20 mg), 28.26% (40 mg) in TCDD + FA groups. FA (5 mg) reduced the incidence of the cleft palate from 55.56% to 17.50% (p = 0.005). There were no significant differences between the TCDD group and 10 mg, 20 mg, 40 mg TCDD + FA groups. Based on the these results, the present study suggests that FA can reduce the incidence of 2,3,7,8-TCDD-indued cleft palate in mice.
Collapse
Affiliation(s)
- Cheng-hao Li
- State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, Chengdu, People's Republic of China, Department of Cleft Lip and Palate Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, People's Republic of China
| | - Bing Shi
- State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, Chengdu, People's Republic of China, Department of Cleft Lip and Palate Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, People's Republic of China
| | - Wei He
- State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, Chengdu, People's Republic of China, Department of Cleft Lip and Palate Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, People's Republic of China
| | - Tian Meng
- State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, Chengdu, People's Republic of China, Department of Cleft Lip and Palate Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, People's Republic of China
| |
Collapse
|
20
|
Experimental study on protection of vitamin B6on TCDD-induced palatal cleft formation in the mice. ACTA ACUST UNITED AC 2009; 86:357-61. [DOI: 10.1002/bdrb.20203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
|
21
|
Park D, Kim S, Kang H, Oh J, Jang JY, Shin S, Kim TK, Choi YJ, Lee SH, Kim KY, Joo SS, Kim YB. Preventive effect of piperonyl butoxide on cyclophosphamide-induced teratogenesis in rats. ACTA ACUST UNITED AC 2009; 86:402-8. [DOI: 10.1002/bdrb.20210] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
22
|
Meng L, Bian Z, Torensma R, Von den Hoff JW. Biological mechanisms in palatogenesis and cleft palate. J Dent Res 2009; 88:22-33. [PMID: 19131313 DOI: 10.1177/0022034508327868] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Clefts of the palate are common birth defects requiring extensive treatment. They appear to be caused by multiple genetic and environmental factors during palatogenesis. This may result in local changes in growth factors, extracellular matrix (ECM), and cell adhesion molecules. Several clefting factors have been implicated by studies in mouse models, while some of these have also been confirmed by genetic screening in humans. Here, we discuss several knockout mouse models to examine the role of specific genes in cleft formation. The cleft is ultimately caused by interference with shelf elevation, attachment, or fusion. Shelf elevation is brought about by mesenchymal proliferation and changes in the ECM induced by growth factors such as TGF-betas. Crucial ECM molecules are collagens, proteoglycans, and glycosaminoglycans. Shelf attachment depends on specific differentiation of the epithelium involving TGF-beta3, sonic hedgehog, and WNT signaling, and correct expression of epithelial adhesion molecules such as E-cadherin. The final fusion requires epithelial apoptosis and epithelium-to-mesenchyme transformation regulated by TGF-beta and WNT proteins. Other factors may interact with these signaling pathways and contribute to clefting. Normalization of the biological mechanisms regulating palatogenesis in susceptible fetuses is expected to contribute to cleft prevention.
Collapse
Affiliation(s)
- L Meng
- Department of Orthodontics and Oral Biology, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | | | | | | |
Collapse
|
23
|
Jang JY, Park D, Shin S, Jeon JH, Choi BI, Joo SS, Hwang SY, Nahm SS, Kim YB. Antiteratogenic effect of resveratrol in mice exposed in utero to 2,3,7,8-tetrachlorodibenzo-p-dioxin. Eur J Pharmacol 2008; 591:280-3. [PMID: 18571640 DOI: 10.1016/j.ejphar.2008.05.033] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Revised: 04/21/2008] [Accepted: 05/20/2008] [Indexed: 11/17/2022]
Abstract
The effect of resveratrol, an aryl hydrocarbon receptor antagonist, on the teratogenicity induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was investigated. Pregnant C57BL/6J mice were orally administered resveratrol (50 mg/kg) for 6 consecutive days, from gestational day (GD) 8 to GD13, followed by an oral challenge with TCDD (14 mug/kg) on GD12. TCDD caused severe fetal malformations including cleft palate (40.7%), renal pelvic dilatation (100%, mean score 3.060), and ureteric dilatation (100%, mean score 3.210) and tortuosity (95.1%). Resveratrol significantly reduced both the incidence of TCDD-induced cleft palate to 18.4% and the degrees of renal pelvic and ureteric dilatations caused by TCDD. The results suggest that pretreatment with resveratrol might bring a beneficial outcome for reducing the incidence and severity of fetal malformations caused by TCDD exposure in utero.
Collapse
Affiliation(s)
- Ja Young Jang
- College of Veterinary Medicine and Research Institute of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk 361-763, Republic of Korea
| | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Aragon AC, Kopf PG, Campen MJ, Huwe JK, Walker MK. In utero and lactational 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure: effects on fetal and adult cardiac gene expression and adult cardiac and renal morphology. Toxicol Sci 2007; 101:321-30. [PMID: 17975115 DOI: 10.1093/toxsci/kfm272] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The mouse heart is a target of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) during fetal development, and microarray analysis demonstrates significant changes in expression of cardiac genes involved in extracellular matrix (ECM) remodeling. We tested the hypothesis that developmental TCDD exposure would disrupt cardiac ECM expression and be associated with changes in cardiac morphology in adulthood. In one study, time-pregnant C57BL/6 mice were dosed with corn oil or 1.5, 3.0, or 6.0 microg TCDD/kg on gestation day (GD) 14.5 and sacrificed on GD 17.5, when changes in fetal cardiac mRNA expression were analyzed using quantitative PCR. TCDD induced mRNA expression of genes associated with ECM remodeling (matrix metalloproteinase 9 and 13, preproendothelin-1 [preproET-1]), cardiac hypertrophy (atrial natriuretic peptide, beta-myosin heavy chain, osteopontin), and aryl hydrocarbon receptor (AHR) activation (cytochrome P4501A1, AHR repressor). Further, all TCDD-induced changes required the AHR since gene expression was not altered in AHR knockout fetuses. In a second study, time-pregnant mice were treated with corn oil or 6.0 microg TCDD/kg on GD 14.5, and male offspring were assessed for changes in cardiac gene expression and cardiac and renal morphology at 3 months. All TCDD-induced changes in cardiac gene expression observed fetally, except for preproET-1, remained induced in the hearts of adult male offspring. Adult male offspring of TCDD-exposed dams also displayed cardiac hypertrophy, decreased plasma volume, and mild hydronephrosis. These results demonstrate that in utero and lactational TCDD exposures alter cardiac gene expression and cardiac and renal morphology in adulthood, which may increase the susceptibility to cardiovascular dysfunction.
Collapse
Affiliation(s)
- Andrea C Aragon
- College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, USA
| | | | | | | | | |
Collapse
|
25
|
Kovacic P, Somanathan R. Mechanism of teratogenesis: Electron transfer, reactive oxygen species, and antioxidants. ACTA ACUST UNITED AC 2007; 78:308-25. [PMID: 17315244 DOI: 10.1002/bdrc.20081] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Teratogenesis has been a topic of increasing interest and concern in recent years, generating controversy in association with danger to humans and other living things. A veritable host of chemicals is known to be involved, encompassing a wide variety of classes, both organic and inorganic. Contact with these chemicals is virtually unavoidable due to contamination of air, water, ground, food, beverages, and household items, as well as exposure to medicinals. The resulting adverse effects on reproduction are numerous. There is uncertainty regarding the mode of action of these chemicals, although various theories have been advanced, e.g., disruption of the central nervous system (CNS), DNA attack, enzyme inhibition, interference with hormonal action, and insult to membranes, proteins, and mitochondria. This review provides extensive evidence for involvement of oxidative stress (OS) and electron transfer (ET) as a unifying theme. Successful application of the mechanistic approach is made to all of the main classes of toxins, in addition to large numbers of miscellaneous types. We believe it is not coincidental that the vast majority of these substances incorporate ET functionalities (quinone, metal complex, ArNO2, or conjugated iminium) either per se or in metabolites, potentially giving rise to reactive oxygen species (ROS) by redox cycling. Some categories, e.g., peroxides and radiation, appear to generate ROS by non-ET routes. Other mechanisms are briefly addressed; a multifaceted approach to mode of action appears to be the most logical. Our framework should increase understanding and contribute to preventative measures, such as use of antioxidants.
Collapse
Affiliation(s)
- Peter Kovacic
- Department of Chemistry, San Diego State University, San Diego, California 92182, USA.
| | | |
Collapse
|
26
|
Dragin N, Dalton TP, Miller ML, Shertzer HG, Nebert DW. For dioxin-induced birth defects, mouse or human CYP1A2 in maternal liver protects whereas mouse CYP1A1 and CYP1B1 are inconsequential. J Biol Chem 2006; 281:18591-600. [PMID: 16636061 DOI: 10.1074/jbc.m601159200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin) induces cleft palate and hydronephrosis in mice, when exposed in utero; these effects are mediated by the aryl hydrocarbon receptor. The Cyp1a1, Cyp1a2, and Cyp1b1 genes are up-regulated by the aryl hydrocarbon receptor. To elucidate their roles in dioxin-induced teratogenesis, we compared Cyp1a1(-/-), Cyp1a2(-/-), and Cyp1b1(-/-) knock-out mice with Cyp1(+/+) wild-type mice. Dioxin was administered (25 microg/kg, gavage) on gestational day 10, and embryos were examined on gestational day 18. The incidence of cleft palate and hydronephrosis was not significantly different in fetuses from Cyp1a1(-/-), Cyp1b1(-/-), and Cyp1(+/+) wild-type mice. To fetuses carried by Cyp1a2(-/-) dams, however, this dose of dioxin was lethal; this effect was absolutely dependent on the maternal Cyp1a2 genotype and independent of the embryonic Cyp1a2 genotype. Dioxin levels were highest in adipose tissue, mammary gland, and circulating blood of Cyp1a2(-/-) mothers, compared with that in the Cyp1(+/+) mothers, who showed highest dioxin levels in liver. More dioxin reached the embryos from Cyp1a2(-/-) dams, compared with that from Cyp1(+/+) dams. Fetuses from Cyp1a2(-/-) dams exhibited a approximately 6-fold increased sensitivity to cleft palate, hydronephrosis, and lethality. Using the humanized hCYP1A1_1A2 transgenic mouse (expressing the human CYP1A1 and CYP1A2 genes in the absence of mouse Cyp1a2 gene), the teratogenic effects of dioxin reverted to the wild-type phenotype. These data indicate that maternal mouse hepatic CYP1A2, by sequestering dioxin and thus altering the pharmacokinetics, protects the embryos from toxicity and birth defects; substitution of the human CYP1A2 trans-gene provides the same protection. In contrast, neither CYP1A1 nor CYP1B1 appears to play a role in dioxin-mediated teratogenesis.
Collapse
Affiliation(s)
- Nadine Dragin
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati Medical Center, Cincinnati, Ohio 45267-0056, USA
| | | | | | | | | |
Collapse
|
27
|
Abbott BD, Best DS, Narotsky MG. Teratogenic effects of retinoic acid are modulated in mice lacking expression of epidermal growth factor and transforming growth factor-alpha. ACTA ACUST UNITED AC 2005; 73:204-17. [PMID: 15799028 DOI: 10.1002/bdra.20117] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Epidermal growth factor (EGF) and transforming growth factor-alpha (TGFalpha) regulate cell proliferation and differentiation in the embryo. The induction of cleft palate (CP) by all trans-retinoic acid (RA) was associated with altered expression of TGFalpha, EGF receptor, and binding of EGF. This study uses knockout (KO) mice to examine the roles of EGF and TGFalpha in teratogenic responses of embryos exposed to RA. METHODS Pregnant wild-type (WT) mice of mixed genetic background, EGF KO, C57BL/6J, and TGFalpha KO mice were given a single oral dose of RA (100 mg/kg, 10 ml/kg) or corn oil on GD 10 at 12 PM, GD 11 at 12 PM or 4 PM, or GD 12 at 8 AM or 12 PM (plug day = GD 0). GD 18 fetuses were examined for external, visceral, and skeletal effects. RESULTS After exposure to RA on GD 12, the incidence of CP in EGF KO was significantly reduced relative to WT. In TGFalpha KO fetuses, RA exposure on GD 10 increased the incidence of CP versus C57BL/6J. The incidence of skeletal defects in the limbs, vertebrae, sternebrae, and ribs were also affected by lack of expression of EGF or TGFalpha with region-specific amelioration or exacerbation of the effects of RA. In TGFalpha KO fetuses, incidences of forelimb long bone and digit defects increased relative to C57BL/6J. In EGF KO fetuses, relative to WT, the incidence of hindlimb oligodactyly was increased. In EGF KO, but not WT, RA produced short, bent radius, humerus, and ulna. Both TGFalpha and EGF KO mice had increased incidences of dilation of the renal pelvis and this was reduced by RA. CONCLUSIONS RA exposure produced skeletal and visceral defects in all genotypes; however, EGF or TGFalpha KO influenced the incidence and severity of defects. This study supports a role for EGF and TGFalpha in the response to RA.
Collapse
Affiliation(s)
- Barbara D Abbott
- Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 2525 East Highway 54, Durham, NC 27713, USA.
| | | | | |
Collapse
|
28
|
Abbott BD, Buckalew AR, Leffler KE. Effects of epidermal growth factor (EGF), transforming growth factor-α (TGFα), and 2,3,7,8-tetrachlorodibenzo-p-dioxin on fusion of embryonic palates in serum-free organ culture using wild-type, EGF knockout, and TGFα knockout mouse strains. ACTA ACUST UNITED AC 2005; 73:447-54. [PMID: 15880701 DOI: 10.1002/bdra.20133] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is teratogenic in mice, producing cleft palate (CP). TCDD exposure disrupts expression of epidermal growth factor (EGF) receptor, EGF, and transforming growth factor-alpha (TGFalpha) in the palate and affects proliferation and differentiation of medial epithelial cells. EGF knockout embryos are less susceptible to the induction of CP by TCDD. This study used palate organ culture to examine the hypothesis that EGF enables a response to TCDD. METHODS The midfacial tissues from wild-type (WT), EGF knockout, C57BL/6J, and TGFalpha knockout embryos were placed in organ culture on gestational day (GD) 12. Palatal explants were cultured for 4 days in serum-free Bigger's (BGJ) medium with 0.1% dimethyl sulfoxide (DMSO) or 1 x 10(-8) M TCDD with or without 2 ng of EGF/ml, 1 or 2 ng of TGFalpha/ml. Effects on palatal fusion were evaluated on day 4 of culture. EGF levels in explants and medium were determined using Luminex technology. RESULTS In serum-free, control medium, palates from all of the strains fused. EGF knockout palates cultured with TCDD (no EGF) fused, but those cultured with TCDD + 2 ng of EGF/ml failed to fuse (p < 0.05 vs. control or TCDD without EGF). TGFalpha knockout palates failed to fuse when cultured with TCDD + 2 ng of TGFalpha/ml. EGF levels increased in tissue and accumulated in the medium after 24 hr of culture. CONCLUSIONS This study demonstrated that providing EGF to the palates of EGF knockout mice restored the response to TCDD. These studies support the hypothesis that the mechanism for induction of CP by TCDD is mediated via the EGFR pathway.
Collapse
Affiliation(s)
- Barbara D Abbott
- Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
| | | | | |
Collapse
|
29
|
Wang SL, Chen TT, Hsu JF, Hsu CC, Chang LW, Ryan JJ, Guo YL, Lambert GH. Neonatal and childhood teeth in relation to perinatal exposure to polychlorinated biphenyls and dibenzofurans: observations of the Yucheng children in Taiwan. ENVIRONMENTAL RESEARCH 2003; 93:131-137. [PMID: 12963397 DOI: 10.1016/s0013-9351(03)00040-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In order to determine the effect of perinatal polychlorinated biphenyls and dibenzofurans (PCBs/PCDFs) exposure on neonatal and childhood teeth in Yucheng children, we carried out complete dental examinations on 73 Yucheng children born to mothers who ingested high levels of PCBs/PCDFs and 75 matched controls, aged 7-11 years, in 1992. Ten of 73 (10%) exposed children were reported to have borne teeth during the neonatal period, while none of the controls did. The exposed group also had a significantly higher percentage of teeth with congenitally missing tooth germ compared to the controls (29 vs 2.7%) or rotation (19 vs 2.7%). The percentages of developmental defects increased significantly with increasing maternal serum PCB levels, childhood PCB and PCDF levels, and the duration of breast feeding. The maternal PCB level clearly played a more important role in an increased risk of neonatal teeth and developmental defects. The defects were apparent from the lowest tertile, with a total PCB level of <10 ppb in maternal serum measured nearest to childbirth. The number of permanent teeth tended to be less in exposed children than in the control group from the age of 11 years onwards. Our present study has demonstrated for the first time a dose-response relationship between perinatal PCBs/PCDFs exposure and dental defects.
Collapse
Affiliation(s)
- Shu-Li Wang
- Division of Environmental Health and Occupational Medicine, National Health Research Institutes, Taiwan
| | | | | | | | | | | | | | | |
Collapse
|
30
|
Matsumura F. On the significance of the role of cellular stress response reactions in the toxic actions of dioxin. Biochem Pharmacol 2003; 66:527-40. [PMID: 12906918 DOI: 10.1016/s0006-2952(03)00157-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Dioxin is known to cause many toxic effects that vary greatly in different tissues, ages, genders, and species. In this review, an attempt has been made to sort out major signaling pathways involved in the expression of the toxicities of dioxin. The major strategy adopted in analyzing its major signaling pathways is to view the toxic actions of dioxin as the result of the Ah receptor-mediated expression of a major cellular emergency stress response signal. Evidence pointing to the similarities between the symptoms of poisoning by dioxin and those produced by chronic administration of typical stressors, particularly lipopolysaccharides (LPS), bacterial endotoxins, has been assembled and analyzed. The common symptoms are wasting syndrome, atherosclerosis, fatty liver, and thymic atrophy. On the other hand, oxidative stress caused by cytochrome P450 induction is one of the typical stresses of dioxin poisoning, but not LPS poisoning. One of the major means through which dioxin triggers stress responses via "stress-activated kinase pathways" is stimulation of the cellular production of cytokines/autocrines, particularly growth factors. In the case of hepatocytes for instance, transforming growth factor-alpha plays a pivotal role in the dioxin-induced activation of the epidermal growth factor receptor and the extracellular signal-related kinase pathway, which acts as a signal to suppress apoptosis induced by cellular stress. These observations as well as additional experimental data support the idea that one of the major functions of the Ah receptor could be the elicitation of cellular stress response reactions. Another key point in understanding the toxic action of dioxin is that, unlike other cases of stressors, dioxin signaling becomes chronically sustained because of its extreme persistence in the human body, its half-life of 7-10 years, and its selective accumulation in fatty target tissues.
Collapse
Affiliation(s)
- Fumio Matsumura
- Department of Environmental Toxicology, University of California, One Shields Avenue, Davis, CA, USA.
| |
Collapse
|