1
|
Bouchard KV, Costin GE. Promoting New Approach Methodologies (NAMs) for research on skin color changes in response to environmental stress factors: tobacco and air pollution. FRONTIERS IN TOXICOLOGY 2023; 5:1256399. [PMID: 37886123 PMCID: PMC10598764 DOI: 10.3389/ftox.2023.1256399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 08/25/2023] [Indexed: 10/28/2023] Open
Abstract
Aging is one of the most dynamic biological processes in the human body and is known to carry significant impacts on individuals' self-esteem. Skin pigmentation is a highly heritable trait made possible by complex, strictly controlled cellular and molecular mechanisms. Genetic, environmental and endocrine factors contribute to the modulation of melanin's amount, type and distribution in the skin layers. One of the hallmarks of extrinsic skin aging induced by environmental stress factors is the alteration of the constitutive pigmentation pattern clinically defined as senile lentigines and/or melasma or other pigmentary dyschromias. The complexity of pollutants and tobacco smoke as environmental stress factors warrants a thorough understanding of the mechanisms by which they impact skin pigmentation through repeated and long-term exposure. Pre-clinical and clinical studies demonstrated that pollutants are known to induce reactive oxygen species (ROS) or inflammatory events that lead directly or indirectly to skin hyperpigmentation. Another mechanistic direction is provided by Aryl hydrocarbon Receptors (AhR) which were shown to mediate processes leading to skin hyperpigmentation in response to pollutants by regulation of melanogenic enzymes and transcription factors involved in melanin biosynthesis pathway. In this context, we will discuss a diverse range of New Approach Methodologies (NAMs) capable to provide mechanistic insights of the cellular and molecular pathways involved in the action of environmental stress factors on skin pigmentation and to support the design of raw ingredients and formulations intended to counter their impact and of any subsequently needed clinical studies.
Collapse
|
2
|
Kim JG, Kang HY, Kim MJ, Lim S, Lee CJ, Kim KM, Jung SK. 4-phenylpyridine suppresses UVB-induced skin inflammation by targeting c-Src in vitro and in vivo. J Cell Mol Med 2022; 26:3891-3901. [PMID: 35686492 PMCID: PMC9279582 DOI: 10.1111/jcmm.17422] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 05/11/2022] [Accepted: 05/20/2022] [Indexed: 11/27/2022] Open
Abstract
Acute or repetitive exposure to ultraviolet (UV) cause disruptions to the skin barrier and subsequent inflammatory skin disease. 4‐phenylpyridine (4‐PP) is a constituent of Brassica campestris L. ssp. Pekinensis and its effect on skin inflammation and molecular target remain unclear. The purpose of this study is to confirm the anti‐inflammatory efficacy of 4‐PP on UVB‐induced skin inflammation in human keratinocytes HaCaT and mouse skin and validation of its molecular target. 4‐PP also attenuated UVB‐induced phosphorylation of p38/mitogen‐activated protein kinase kinase (MKK) 3/6, c‐Jun N‐terminal kinase 1/2, MKK 4/7, extracellular‐signal‐regulated kinase 1/2, mitogen‐activated protein kinase 1/2. Additionally, 4‐PP inhibited UVB‐induced phosphorylation of epidermal growth factor receptor (EGFR) Y1068, Y1045 and 854 residues but not the proto‐oncogene tyrosine‐protein kinase c‐Src. Drug affinity responsive target stability assay revealed that 4‐PP directly binds to c‐Src and inhibits pronase c‐proteolysis. Knockdown of c‐Src inhibited UVB‐induced COX‐2 expression and phosphorylation of MAPKs and EGFR in HaCaT cells. Dorsal treatment of 4‐PP prevented UVB (0.5 J/cm2)‐induced skin thickness, phosphorylation of EGFR and COX‐2 expression in mouse skin. Our findings suggest that 4‐PP can be used as anti‐inflammatory agent with an effect of skin inflammation by inhibiting the COX‐2 expression via suppressing the c‐Src/EGFR/MAPKs signalling pathway.
Collapse
Affiliation(s)
- Ju Gyeong Kim
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, Korea
| | - Ha Yeong Kang
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, Korea
| | - Min Jeong Kim
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, Korea
| | - Seokwon Lim
- Department of Food Science and Biotechnology, Gachon University, Seongnam-si, Gyeonggi-do, Korea
| | - Chang Joo Lee
- Department of Food Science and Biotechnology, Wonkwang University, Iksan, Korea
| | - Kyung-Min Kim
- School of Applied Biosciences, Kyungpook National University, Daegu, Korea
| | - Sung Keun Jung
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, Korea.,Research Institute of Tailored Food Technology, Kyungpook National University, Daegu, Korea
| |
Collapse
|
3
|
Gao S, Guo K, Chen Y, Zhao J, Jing R, Wang L, Li X, Hu Z, Xu N, Li X. Keratinocyte Growth Factor 2 Ameliorates UVB-Induced Skin Damage via Activating the AhR/Nrf2 Signaling Pathway. Front Pharmacol 2021; 12:655281. [PMID: 34163354 PMCID: PMC8215442 DOI: 10.3389/fphar.2021.655281] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 05/24/2021] [Indexed: 12/22/2022] Open
Abstract
Objective: Exposure to ultraviolet B (UVB) can cause skin damage through oxidative stress, DNA damage, and apoptosis. Keratinocyte growth factor (KGF) has been shown to reduce the content of intracellular reactive oxygen species (ROS) following UVB exposure, a role that is crucial for the efficient photoprotection of skin. The present study evaluated the photoprotective effect of KGF-2 on UVB-induced skin damage and explored its potential molecular mechanism. Methods: To evaluate the effect of KGF-2 on UVB-induced damage ex vivo, a human epidermal full-thickness skin equivalent was pretreated without or with KGF-2 and then exposed to UVB and the levels of histopathological changes, DNA damage, inflammation, and apoptosis were then evaluated. The ability of KGF-2 to protect the cells against UVB-inflicted damage and its effect on ROS production, apoptosis, and mitochondrial dysfunction were determined in HaCaT cells. Results: Pretreatment of the epidermis with KGF-2 ameliorated the extent of photodamage. At the cellular level, KGF-2 could attenuate ROS production, apoptosis, DNA damage, and mitochondrial dysfunction caused by UVB exposure. KGF-2 could also activate the aryl hydrocarbon receptor (AhR) to trigger the Nrf2 signaling pathway. Conclusion: Taken together, our findings suggested that KGF-2 could ameliorate UVB-induced skin damage through inhibiting apoptosis, reducing oxidative stress, and preventing DNA damage and mitochondrial dysfunction via regulating AhR/Nrf2 signaling pathway.
Collapse
Affiliation(s)
- Shuang Gao
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Keke Guo
- College of Life and Environmental Sciences, Wenzhou University, Wenzhou, China
| | - Yu Chen
- College of Life and Environmental Sciences, Wenzhou University, Wenzhou, China
| | - Jungang Zhao
- College of Life and Environmental Sciences, Wenzhou University, Wenzhou, China
| | - Rongrong Jing
- College of Life and Environmental Sciences, Wenzhou University, Wenzhou, China
| | - Lusheng Wang
- College of Life and Environmental Sciences, Wenzhou University, Wenzhou, China
| | - Xuenan Li
- College of Life and Environmental Sciences, Wenzhou University, Wenzhou, China
| | - Zhenlin Hu
- College of Life and Environmental Sciences, Wenzhou University, Wenzhou, China
| | - Nuo Xu
- College of Life and Environmental Sciences, Wenzhou University, Wenzhou, China
| | - Xiaokun Li
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| |
Collapse
|
4
|
A New Insight into the Potential Role of Tryptophan-Derived AhR Ligands in Skin Physiological and Pathological Processes. Int J Mol Sci 2021; 22:ijms22031104. [PMID: 33499346 PMCID: PMC7865493 DOI: 10.3390/ijms22031104] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 01/15/2021] [Accepted: 01/19/2021] [Indexed: 12/31/2022] Open
Abstract
The aryl hydrocarbon receptor (AhR) plays a crucial role in environmental responses and xenobiotic metabolism, as it controls the transcription profiles of several genes in a ligand-specific and cell-type-specific manner. Various barrier tissues, including skin, display the expression of AhR. Recent studies revealed multiple roles of AhR in skin physiology and disease, including melanogenesis, inflammation and cancer. Tryptophan metabolites are distinguished among the groups of natural and synthetic AhR ligands, and these include kynurenine, kynurenic acid and 6-formylindolo[3,2-b]carbazole (FICZ). Tryptophan derivatives can affect and regulate a variety of signaling pathways. Thus, the interest in how these substances influence physiological and pathological processes in the skin is expanding rapidly. The widespread presence of these substances and potential continuous exposure of the skin to their biological effects indicate the important role of AhR and its ligands in the prevention, pathogenesis and progression of skin diseases. In this review, we summarize the current knowledge of AhR in skin physiology. Moreover, we discuss the role of AhR in skin pathological processes, including inflammatory skin diseases, pigmentation disorders and cancer. Finally, the impact of FICZ, kynurenic acid, and kynurenine on physiological and pathological processes in the skin is considered. However, the mechanisms of how AhR regulates skin function require further investigation.
Collapse
|
5
|
Baicalein Inhibits Benzo[a]pyrene-Induced Toxic Response by Downregulating Src Phosphorylation and by Upregulating NRF2-HMOX1 System. Antioxidants (Basel) 2020; 9:antiox9060507. [PMID: 32526964 PMCID: PMC7346154 DOI: 10.3390/antiox9060507] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 06/08/2020] [Indexed: 12/17/2022] Open
Abstract
Benzo[a]pyrene (BaP), a major environmental pollutant, activates aryl hydrocarbon receptor (AHR), induces its cytoplasmic-to-nuclear translocation and upregulates the production of cytochrome P450 1A1 (CYP1A1), a xenobiotic metabolizing enzyme which metabolize BaP. The BaP-AHR-CYP1A1 axis generates reactive oxygen species (ROS) and induces proinflammatory cytokines. Although the anti-inflammatory phytochemical baicalein (BAI) is known to inhibit the BaP-AHR-mediated CYP1A1 expression, its subcellular signaling remains elusive. In this study, normal human epidermal keratinocytes and HaCaT keratinocytes were treated with BAI, BaP, or BAI + BaP, and assessed for the CYP1A1 expression, antioxidative pathways, ROS generation, and proinflammatory cytokine expressions. BAI and BAI-containing herbal medicine Wogon and Oren-gedoku-to could inhibit the BaP-induced CYP1A1 expression. In addition, BAI activated antioxidative system nuclear factor-erythroid 2-related factor-2 (NRF2) and heme oxygenase 1 (HMOX1), leading the reduction of BaP-induced ROS production. The BaP-induced IL1A and IL1B was also downregulated by BAI. BAI inhibited the phosphorylation of Src, a component of AHR cytoplasmic complex, which eventually interfered with the cytoplasmic-to-nuclear translocation of AHR. These results indicate that BAI and BAI-containing herbal drugs may be useful for inhibiting the toxic effects of BaP via dual AHR-CYP1A1-inhibiting and NRF2-HMOX1-activating activities.
Collapse
|
6
|
Kim HR, Kang SY, Kim HO, Park CW, Chung BY. Role of Aryl Hydrocarbon Receptor Activation and Autophagy in Psoriasis-Related Inflammation. Int J Mol Sci 2020; 21:ijms21062195. [PMID: 32235789 PMCID: PMC7139675 DOI: 10.3390/ijms21062195] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/20/2020] [Accepted: 03/20/2020] [Indexed: 02/07/2023] Open
Abstract
Aryl hydrocarbon receptor (AhR) and autophagy reportedly regulate immune responses in the skin. This study explored the effects of AhR activation on autophagy in human keratinocytes, and the relevance of AhR and autophagy in psoriasis pathogenesis. AhR activation by 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) repressed autophagy, while autophagy inhibition induced AhR activation in HaCaT cells and normal human epidermal keratinocytes (NHEKs). A particularly strong interaction between AhR and autophagy was observed in proinflammatory cytokines-stimulated keratinocytes, an in vitro model of psoriasis. In skin biopsies from psoriasis patients, a similar impact of AhR on autophagy and inflammation was observed. AhR inhibition blocked TCDD- and chloroquine-induced p65NF-κB and p38MAPK phosphorylation in proinflammatory cytokines-stimulated HaCaT cells. Moreover, higher expression of AhR and CYP1A1, and lower expression of LC3, were detected in psoriatic skin tissues, compared to the controls. These data demonstrated that AhR modulated autophagy leads to skin inflammation in human keratinocytes via the p65NF-κB/p38MAPK signaling pathways, suggesting that AhR signaling and autophagy might be involved in the pathogenesis of chronic inflammatory disorders such as psoriasis.
Collapse
Affiliation(s)
| | | | | | | | - Bo Young Chung
- Correspondence: ; Tel.: +82-2-829-5221; Fax: +82-2-832-3237
| |
Collapse
|
7
|
Role of the Aryl Hydrocarbon Receptor in Environmentally Induced Skin Aging and Skin Carcinogenesis. Int J Mol Sci 2019; 20:ijms20236005. [PMID: 31795255 PMCID: PMC6928879 DOI: 10.3390/ijms20236005] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 11/22/2019] [Accepted: 11/27/2019] [Indexed: 12/19/2022] Open
Abstract
The skin is constantly exposed to a variety of environmental threats, including solar electromagnetic radiation, microbes, airborne particulate matter, and chemicals. Acute exposure to these environmental factors results in the activation of different signaling pathways that orchestrate adaptive stress responses to maintain cell and tissue homeostasis. Chronic exposure of skin to these factors, however, may lead to the accumulation of damaged macromolecules and loss of cell and tissue integrity, which, over time, may facilitate aging processes and the development of aging-related malignancies. One transcription factor that is expressed in all cutaneous cells and activated by various environmental stressors, including dioxins, polycyclic aromatic hydrocarbons, and ultraviolet radiation, is the aryl hydrocarbon receptor (AHR). By regulating keratinocyte proliferation and differentiation, epidermal barrier function, melanogenesis, and immunity, a certain degree of AHR activity is critical to maintain skin integrity and to adapt to acute stress situations. In contrast, a chronic activation of cutaneous AHR signaling critically contributes to premature aging and the development of neoplasms by affecting metabolism, extracellular matrix remodeling, inflammation, pigmentation, DNA repair, and apoptosis. This article provides an overview of the detrimental effects associated with sustained AHR activity in chronically stressed skin and pinpoints AHR as a promising target for chemoprevention.
Collapse
|
8
|
Antioxidants from Plants Protect against Skin Photoaging. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:1454936. [PMID: 30174780 PMCID: PMC6098906 DOI: 10.1155/2018/1454936] [Citation(s) in RCA: 111] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 07/05/2018] [Accepted: 07/11/2018] [Indexed: 02/06/2023]
Abstract
Exposure to UV light triggers the rapid generation and accumulation of reactive oxygen species (ROS) in skin cells, with consequent increase in oxidative stress and thus in photoaging. Exogenous supplementation with dietary antioxidants and/or skin pretreatment with antioxidant-based lotions before sun exposure might be a winning strategy against age-related skin pathologies. In this context, plants produce many secondary metabolites to protect themselves from UV radiations and these compounds can also protect the skin from photoaging. Phenolic compounds, ascorbic acid and carotenoids, derived from different plant species, are able to protect the skin by preventing UV penetration, reducing inflammation and oxidative stress, and influencing several survival signalling pathways. In this review, we focus our attention on the double role of oxidants in cell metabolism and on environmental and xenobiotic agents involved in skin photoaging. Moreover, we discuss the protective role of dietary antioxidants from fruits and vegetables and report their antiaging properties related to the reduction of oxidative stress pathways.
Collapse
|
9
|
The AHR represses nucleotide excision repair and apoptosis and contributes to UV-induced skin carcinogenesis. Cell Death Differ 2018; 25:1823-1836. [PMID: 30013037 PMCID: PMC6180092 DOI: 10.1038/s41418-018-0160-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 06/18/2018] [Accepted: 06/25/2018] [Indexed: 12/20/2022] Open
Abstract
Ultraviolet B (UVB) radiation induces mutagenic DNA photoproducts, in particular cyclobutane pyrimidine dimers (CPDs), in epidermal keratinocytes (KC). To prevent skin carcinogenesis, these DNA photoproducts must be removed by nucleotide excision repair (NER) or apoptosis. Here we report that the UVB-sensitive transcription factor aryl hydrocarbon receptor (AHR) attenuates the clearance of UVB-induced CPDs in human HaCaT KC and skin from SKH-1 hairless mice. Subsequent RNA interference and inhibitor studies in KC revealed that AHR specifically suppresses global genome but not transcription-coupled NER. In further experiments, we found that the accelerated repair of CPDs in AHR-compromised KC depended on a modulation of the p27 tumor suppressor protein. Accordingly, p27 protein levels were increased in AHR-silenced KC and skin biopsies from AHR−/− mice, and critical for the improvement of NER. Besides increasing NER activity, AHR inhibition was accompanied by an enhanced occurrence of DNA double-strand breaks triggering KC apoptosis at later time points after irradiation. The UVB-activated AHR thus acts as a negative regulator of both early defense systems against carcinogenesis, NER and apoptosis, implying that it exhibits tumorigenic functions in UVB-exposed skin. In fact, AHR−/− mice developed 50% less UVB-induced cutaneous squamous cell carcinomas in a chronic photocarcinogenesis study than their AHR+/+ littermates. Taken together, our data reveal that AHR influences DNA damage-dependent responses in UVB-irradiated KC and critically contributes to skin photocarcinogenesis in mice.
Collapse
|
10
|
Aryl hydrocarbon receptor (AhR) a possible target for the treatment of skin disease. Med Hypotheses 2018; 116:96-100. [PMID: 29857917 DOI: 10.1016/j.mehy.2018.05.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/21/2018] [Accepted: 05/07/2018] [Indexed: 01/03/2023]
Abstract
Aryl hydrocarbon receptor (AhR) is a transcription factor expressed in all skin cells type. It responds to exogenous and endogenous chemicals by inducing/repressing the expression of several genes with toxic or protective effects in a wide range of species and tissues. In healthy skin, AhR signalling contributes to keratinocytes differentiation, skin barrier function, skin pigmentation, and mediates oxidative stress. In the last years, some studies have shown that AhR seems to be involved in the pathogenesis of some skin diseases, even if the currently available data are contradictory. Indeed, while the blocking the AhR signalling activity could prevent or treat skin cancer, the AhR activation seems to be advantageous for the treatment of inflammatory skin diseases. Therefore, for its multifaceted role in skin diseases, AhR seems to be an attractive therapeutic target. Indeed, recently some molecules have been identified for the prevention of skin cancer and the treatment of inflammatory skin diseases.
Collapse
|
11
|
Noakes R. Dissecting the enigma of scleroderma: possible involvement of the kynurenine pathway. Pteridines 2017. [DOI: 10.1515/pterid-2016-0010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
The kynurenine pathway (KP) is the metabolic pathway via which L-tryptophan is converted to nicotinamide. It serves important immune-regulatory roles. This article will review the evidence for involvement of the KP in scleroderma and present a possible model of kynurenine regulation of the cytokine cascade.
Collapse
Affiliation(s)
- Rowland Noakes
- Queensland Institute of Dermatology, Greenslopes Private Hospital , Greenslopes , QLD 4120, Australia
| |
Collapse
|
12
|
Mancebo SE, Wang SQ. Recognizing the impact of ambient air pollution on skin health. J Eur Acad Dermatol Venereol 2015; 29:2326-32. [PMID: 26289769 DOI: 10.1111/jdv.13250] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Accepted: 05/12/2015] [Indexed: 01/06/2023]
Abstract
Ambient air pollution is a known public health hazard that negatively impacts non-cutaneous organs; however, our knowledge regarding the effects on skin remains limited. Current scientific evidence suggests there are four mechanisms by which ambient air pollutants cause adverse effects on skin health: (i) generation of free radicals, (ii) induction of inflammatory cascade and subsequent impairment of skin barrier, (iii) activation of the aryl hydrocarbon receptor (AhR) and (iv) alterations to skin microflora. In this review, we provide a comprehensive overview on ambient air pollutants and their relevant sources, and highlight current evidence of the effects on skin.
Collapse
Affiliation(s)
- S E Mancebo
- Dermatology Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - S Q Wang
- Dermatology Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| |
Collapse
|
13
|
Noakes R. The aryl hydrocarbon receptor: a review of its role in the physiology and pathology of the integument and its relationship to the tryptophan metabolism. Int J Tryptophan Res 2015; 8:7-18. [PMID: 25733915 PMCID: PMC4327407 DOI: 10.4137/ijtr.s19985] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 01/04/2015] [Accepted: 01/13/2015] [Indexed: 02/07/2023] Open
Abstract
The aryl hydrocarbon receptor (AHR) is a cytosolic receptor for low molecular weight molecules, of which the most widely recognized ligand is 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and the most widely recognized effect, chloracne. Adverse effects of manipulation were most recently and graphically demonstrated by the poisoning of Viktor Yushchenko during the Ukrainian presidential elections of 2004. However, recent research has revealed a receptor with wide-ranging, and at times, paradoxical actions. It was arguably among the first biological receptors to be utilized by dermatologists, dating from the time of topical tar preparations as a therapeutic agent. I provide a review outlining the role AHR plays in the development, cellular oxidation/antioxidation, responses to ultraviolet light, melanogenesis, epidermal barrier function, and immune regulation and its relationship to tryptophan metabolism. Finally, I will review the role of AHR in diseases of the integument.
Collapse
Affiliation(s)
- Rowland Noakes
- Queensland Institute of Dermatology, Holland Park, Queensland, Australia
| |
Collapse
|
14
|
The Tryptophan-Derived Endogenous Aryl Hydrocarbon Receptor Ligand 6-Formylindolo[3,2-b]Carbazole Is a Nanomolar UVA Photosensitizer in Epidermal Keratinocytes. J Invest Dermatol 2014; 135:1649-1658. [PMID: 25431849 PMCID: PMC4430374 DOI: 10.1038/jid.2014.503] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 10/24/2014] [Accepted: 11/07/2014] [Indexed: 01/23/2023]
Abstract
Endogenous UVA-chromophores may act as sensitizers of oxidative stress underlying cutaneous photoaging and photocarcinogenesis, but the molecular identity of non-DNA key chromophores displaying UVA-driven photodyamic activity in human skin remains largely undefined. Here we report that 6-formylindolo[3,2-b]carbazole (FICZ), a tryptophan photoproduct and endogenous high affinity aryl hydrocarbon receptor (AhR) agonist, acts as a nanomolar photosensitizer potentiating UVA-induced oxidative stress irrespective of AhR ligand activity. In human HaCaT and primary epidermal keratinocytes, photodynamic induction of apoptosis was elicited by the combined action of solar simulated UVA and FICZ, whereas exposure to the isolated action of UVA or FICZ did not impair viability. In a human epidermal tissue reconstruct, FICZ/UVA-cotreatment caused pronounced phototoxicity inducing keratinocyte cell death, and FICZ photodynamic activity was also substantiated in a murine skin exposure model. Array analysis revealed pronounced potentiation of cellular heat shock, ER stress, and oxidative stress response gene expression observed only upon FICZ/UVA-cotreatment. FICZ photosensitization caused intracellular oxidative stress, and comet analysis revealed introduction of formamidopyrimidine-DNA glycosylase (FPG)-sensitive oxidative DNA lesions suppressible by antioxidant cotreatment. Taken together, our data demonstrate that the endogenous AhR ligand FICZ displays nanomolar photodynamic activity representing a molecular mechanism of UVA-induced photooxidative stress potentially operative in human skin.
Collapse
|
15
|
Role of AhR/ARNT system in skin homeostasis. Arch Dermatol Res 2014; 306:769-79. [PMID: 24966027 PMCID: PMC4220966 DOI: 10.1007/s00403-014-1481-7] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 04/27/2014] [Accepted: 05/22/2014] [Indexed: 11/04/2022]
Abstract
Aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that binds to structurally diverse synthetic and naturally occurring chemicals including dioxins, flavonoids, tryptophan photoproducts, and Malassezia metabolites. Upon binding to its ligands, cytoplasmic AhR translocates to the nucleus, heterodimerizes with aryl hydrocarbon receptor nuclear translocator (ARNT), and mediates numerous biological and toxicological effects by inducing the transcription of various AhR-responsive genes. AhR ligation controls oxidation/antioxidation, epidermal barrier function, photo-induced response, melanogenesis, and innate immunity. This review summarizes recent advances in the understanding of the regulatory mechanisms of skin homeostasis mediated by the AhR/ARNT system.
Collapse
|
16
|
Tigges J, Krutmann J, Fritsche E, Haendeler J, Schaal H, Fischer JW, Kalfalah F, Reinke H, Reifenberger G, Stühler K, Ventura N, Gundermann S, Boukamp P, Boege F. The hallmarks of fibroblast ageing. Mech Ageing Dev 2014; 138:26-44. [PMID: 24686308 DOI: 10.1016/j.mad.2014.03.004] [Citation(s) in RCA: 156] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2013] [Revised: 03/11/2014] [Accepted: 03/18/2014] [Indexed: 12/26/2022]
Abstract
Ageing is influenced by the intrinsic disposition delineating what is maximally possible and extrinsic factors determining how that frame is individually exploited. Intrinsic and extrinsic ageing processes act on the dermis, a post-mitotic skin compartment mainly consisting of extracellular matrix and fibroblasts. Dermal fibroblasts are long-lived cells constantly undergoing damage accumulation and (mal-)adaptation, thus constituting a powerful indicator system for human ageing. Here, we use the systematic of ubiquitous hallmarks of ageing (Lopez-Otin et al., 2013, Cell 153) to categorise the available knowledge regarding dermal fibroblast ageing. We discriminate processes inducible in culture from phenomena apparent in skin biopsies or primary cells from old donors, coming to the following conclusions: (i) Fibroblasts aged in culture exhibit most of the established, ubiquitous hallmarks of ageing. (ii) Not all of these hallmarks have been detected or investigated in fibroblasts aged in situ (in the skin). (iii) Dermal fibroblasts aged in vitro and in vivo exhibit additional features currently not considered ubiquitous hallmarks of ageing. (iv) The ageing process of dermal fibroblasts in their physiological tissue environment has only been partially elucidated, although these cells have been a preferred model of cell ageing in vitro for decades.
Collapse
Affiliation(s)
- Julia Tigges
- Leibniz Research Institute for Environmental Medicine (IUF), Düsseldorf, Germany
| | - Jean Krutmann
- Leibniz Research Institute for Environmental Medicine (IUF), Düsseldorf, Germany
| | - Ellen Fritsche
- Leibniz Research Institute for Environmental Medicine (IUF), Düsseldorf, Germany
| | - Judith Haendeler
- Leibniz Research Institute for Environmental Medicine (IUF), Düsseldorf, Germany; Institute of Clinical Chemistry and Laboratory Diagnostics, Heinrich-Heine-University, Med. Faculty, Düsseldorf, Germany
| | - Heiner Schaal
- Center for Microbiology and Virology, Institute of Virology, Heinrich-Heine-University, Med. Faculty, D-40225 Düsseldorf, Germany
| | - Jens W Fischer
- Institute for Pharmacology and Clinical Pharmacology, Heinrich-Heine-University, Med. Faculty, Düsseldorf, Germany
| | - Faiza Kalfalah
- Institute of Clinical Chemistry and Laboratory Diagnostics, Heinrich-Heine-University, Med. Faculty, Düsseldorf, Germany
| | - Hans Reinke
- Leibniz Research Institute for Environmental Medicine (IUF), Düsseldorf, Germany; Institute of Clinical Chemistry and Laboratory Diagnostics, Heinrich-Heine-University, Med. Faculty, Düsseldorf, Germany
| | - Guido Reifenberger
- Department of Neuropathology, Heinrich-Heine-University, Med. Faculty, Düsseldorf, Germany
| | - Kai Stühler
- Institute for Molecular Medicine, Heinrich-Heine-University, Med. Faculty, Düsseldorf, Germany; Molecular Proteomics Laboratory, Centre for Biological and Medical Research (BMFZ), Heinrich-Heine-University, Düsseldorf, Germany
| | - Natascia Ventura
- Leibniz Research Institute for Environmental Medicine (IUF), Düsseldorf, Germany; Institute of Clinical Chemistry and Laboratory Diagnostics, Heinrich-Heine-University, Med. Faculty, Düsseldorf, Germany
| | | | - Petra Boukamp
- German Cancer Research Centre (DKFZ), Heidelberg, Germany
| | - Fritz Boege
- Institute of Clinical Chemistry and Laboratory Diagnostics, Heinrich-Heine-University, Med. Faculty, Düsseldorf, Germany.
| |
Collapse
|
17
|
Abstract
Multiple molecular mechanisms are involved in the promotion of skin carcinogenesis. Induction of sustained proliferation and epidermal hyperplasia by direct activation of mitotic signaling pathways or indirectly in response to chronic wounding and/or inflammation, or due to a block in terminal differentiation or resistance to apoptosis is necessary to allow clonal expansion of initiated cells with DNA mutations to form skin tumors. The mitotic pathways include activation of epidermal growth factor receptor and Ras/Raf/mitogen-activated protein kinase signaling. Chronic inflammation results in inflammatory cell secretion of growth factors and cytokines such as tumor necrosis factor-α and interleukins, as well as production of reactive oxygen species, all of which can stimulate proliferation. Persistent activation of these pathways leads to tumor promotion.
Collapse
|
18
|
Tigges J, Haarmann-Stemmann T, Vogel CFA, Grindel A, Hübenthal U, Brenden H, Grether-Beck S, Vielhaber G, Johncock W, Krutmann J, Fritsche E. The new aryl hydrocarbon receptor antagonist E/Z-2-benzylindene-5,6-dimethoxy-3,3-dimethylindan-1-one protects against UVB-induced signal transduction. J Invest Dermatol 2013; 134:556-559. [PMID: 23995519 DOI: 10.1038/jid.2013.362] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Julia Tigges
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | | | - Christoph F A Vogel
- Department of Environmental Toxicology and Center for Health and the Environment, University of California, Davis, Davis, California, USA
| | - Annemarie Grindel
- Department of Environmental Toxicology and Center for Health and the Environment, University of California, Davis, Davis, California, USA
| | - Ulrike Hübenthal
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Heidi Brenden
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | | | | | | | - Jean Krutmann
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany.
| | - Ellen Fritsche
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| |
Collapse
|
19
|
Frauenstein K, Sydlik U, Tigges J, Majora M, Wiek C, Hanenberg H, Abel J, Esser C, Fritsche E, Krutmann J, Haarmann-Stemmann T. Evidence for a novel anti-apoptotic pathway in human keratinocytes involving the aryl hydrocarbon receptor, E2F1, and checkpoint kinase 1. Cell Death Differ 2013; 20:1425-34. [PMID: 23912710 DOI: 10.1038/cdd.2013.102] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2013] [Revised: 06/14/2013] [Accepted: 07/04/2013] [Indexed: 01/22/2023] Open
Abstract
Exposure of keratinocytes (KC) to ultraviolet (UV) radiation results in the initiation of apoptosis, a protective mechanism that eliminates cells harboring irreparable DNA damage. Hence, a manipulation of UV-induced apoptosis may significantly influence photocarcinogenesis. We have discovered that the aryl hydrocarbon receptor (AHR), a key regulator of drug metabolism and an UVB-sensitive transcription factor, serves an anti-apoptotic function in UVB-irradiated human KC. Chemical and shRNA-mediated inhibition of AHR signaling sensitized KC to UVB-induced apoptosis by decreasing the expression of E2F1 and its target gene checkpoint kinase 1 (CHK1). The decreased expression of these cell-cycle regulators was due to an enhanced expression of p27(KIP1) and an associated decrease in phosphorylation of both cyclin-dependent kinase 2 and its substrate molecule retinoblastoma protein. The subsequent inhibition of E2F1 autoregulation and downstream CHK1 expression resulted in an enhanced susceptibility of damaged cells to undergo apoptosis. Accordingly, ectopic overexpression of either E2F1 or CHK1 in AHR-knockdown KC attenuated the observed sensitization to UVB-induced apoptosis. Using an AHR-knockout SKH-1 hairless mouse model, we next demonstrated the physiological relevance of the anti-apoptotic function of AHR. In contrast to their AHR-proficient littermates, the constitutive expression of E2F1 and CHK1 was significantly reduced in the skin of AHR-knockout mice. Accordingly, a single exposure of the animals to UVB resulted in an enhanced cleavage of caspase-3 in the skin of AHR-knockout mice. These results identify for the first time the AHR-E2F1-CHK1 axis as a novel anti-apoptotic pathway in KC, which may represent a suitable target for chemoprevention of non-melanoma skin cancer.
Collapse
Affiliation(s)
- K Frauenstein
- IUF-Leibniz Research Institute for Environmental Medicine, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Dupont E, Gomez J, Bilodeau D. Beyond UV radiation: a skin under challenge. Int J Cosmet Sci 2013; 35:224-32. [PMID: 23406155 DOI: 10.1111/ics.12036] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Revised: 12/07/2012] [Accepted: 12/17/2012] [Indexed: 12/27/2022]
Abstract
Since ancient times, human beings have been trying to protect their skin against the adverse effects of the sun. From the first mineral sunscreens used by Egyptians, to the current more sophisticated ultraviolet (UVA/UVB) organic sunscreens, progress has been made in terms of sun protection and deeper knowledge of skin physiology has been acquired in the process. The solar spectrum is composed of radiations of various wavelengths having specific, as well as overlapping effects on skin. UVB is mainly responsible for sunburn and DNA dimer formation that can lead to mutation. UVA generates oxidative reactions affecting DNA, proteins and lipids, and is also immunosuppressive. Recently, visible light and infrared radiation (IR) have been associated with oxidative damage and IR has been additionally linked to adverse heat effects on skin. Numerous other extrinsic factors, related to environment and lifestyle, also affect the appearance of skin, precipitating ageing. New molecular mechanisms linking sun and environmental factors to skin ageing have been identified: IR affects mitochondrial integrity and specific heat receptors also mediate some of its effects, tryptophan is a chromophore for UVB, and the aryl hydrocarbon receptor (AhR) is activated by light and xenobiotics to alter skin physiology. Integrating all these new elements is changing the way we think about skin extrinsic ageing. Is UVA/UVB sunscreen protection still enough for our skin?
Collapse
Affiliation(s)
- E Dupont
- Immanence IDC Inc, 3229 Ch. Quatre-Bourgeois, Bureau 600, Québec, Québec G1W 0C1, Canada
| | | | | |
Collapse
|
21
|
Jing H, Shen G, Wang G, Zhang F, Li Y, Luo F, Yao J, Tian XF. MG132 alleviates liver injury induced by intestinal ischemia/reperfusion in rats: involvement of the AhR and NFκB pathways. J Surg Res 2011; 176:63-73. [PMID: 22079846 DOI: 10.1016/j.jss.2011.09.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 06/20/2011] [Accepted: 09/01/2011] [Indexed: 02/05/2023]
Abstract
BACKGROUND MG132 is a potent antioxidant and has been reported to play a protective role in ischemia/reperfusion (I/R) of many organs. Recent studies have shown that the Aryl hydrocarbon receptor (AhR) may play a beneficial role in I/R of many organs and an AhR agonist has been implicated in an anti-inflammatory role. MG132 might function as an AhR agonist through proteasome inhibition, possibly through the inhibition of NFκB. Herein, we hypothesized that MG132 may play a protective role in liver injury induced by intestinal I/R and we analyzed the expression behavior of AhR and NFκB to determine whether the two factors play a role in intestinal I/R. MATERIALS AND METHODS Thirty-two Sprague-Dawley rats were divided into four groups: control, I/R, MG132 control, and MG132 pretreatment. The I/R and MG132 pretreatment groups were subjected to mesenteric arterial ischemia for 1 h and reperfusion for 3 h. The control and MG132 control groups underwent surgical preparation including isolation of the superior mesenteric artery (SMA) without occlusion. The MG132 control and MG132 pretreatment groups were subjected to intraperitoneal administration of 0.5 mg/kg MG132 30 min before surgery. We collected serum specimens to measure TNF-α, IL-6, liver tissue levels of malondialdehyde (MDA), AhR, and cyp1a2; NFκB, IκBα, and ICAM-1 were also tested. Histologic changes of liver and intestine were subsequently evaluated. RESULTS Compared with the control group, significant increases in MDA, NFκB, and ICAM-1 levels were accompanied by decreases in AhR, cyp1a2, and IκBα expression in the liver in the I/R group, which is consistent with liver and intestinal tissue injury. MG132 blocked the alterations of the indicators above. There were no changes in the MG132 control group compared with the control group in the indicators above. CONCLUSIONS This study demonstrated that MG132 has a significant effect in protection against liver injury induced by intestinal I/R, which may be due to modulation of the AhR and NFκB pathways.
Collapse
Affiliation(s)
- Huirong Jing
- Department of General Surgery, Second Affiliated Hospital of Dalian Medical University, Dalian, China
| | | | | | | | | | | | | | | |
Collapse
|
22
|
Gaitanis G, Velegraki A, Magiatis P, Pappas P, Bassukas ID. Could Malassezia yeasts be implicated in skin carcinogenesis through the production of aryl-hydrocarbon receptor ligands? Med Hypotheses 2011; 77:47-51. [PMID: 21444158 DOI: 10.1016/j.mehy.2011.03.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 03/07/2011] [Indexed: 01/09/2023]
Abstract
UNLABELLED Malassezia yeasts are found on the skin of all humans and many warm-blooded animals. In vitro they have the ability to synthesize potent ligands (indolo[3,2-b]carbazole, malassezin and indirubin) of the aryl-hydrocarbon receptor (AhR; synonym: dioxin receptor) when the sweat contained L-tryptophan is used as the single nitrogen source. The production of these AhR-ligands has been associated with pathogenic strains of a certain Malassezia species (Malassezia furfur) but recent evidence shows that this property is widely distributed in almost all currently known Malassezia species. AhR is associated with carcinogenesis and the potential connection of these ubiquitous skin symbionts, and putative pathogens, with skin neoplasia should be evaluated mainly focusing on mechanisms related to the distinctive ability of the yeast to produce potent AhR ligands. HYPOTHESIS Synthesis of available pertinent data show a possible link between Malassezia produced AhR ligands and skin carcinogenesis, particularly of basal cell carcinoma (BCC). BCCs are almost exclusively observed in animal species colonized by Malassezia. In humans and animals there is overlapping in the skin regions colonized by this yeast and affected by BCC. The potent AhR ligands synthesized by pathogenic Malassezia strains could contribute to tumor promotion by: modification of the UV radiation carcinogenesis, alterations in the salvage/survival of initiated tumor cells, inhibition of cell senescence, interaction with vitamin D metabolism, promotion of immune tolerance and finally pro-carcinogenic modulation of cell cycle progression and apoptosis.
Collapse
Affiliation(s)
- G Gaitanis
- Department of Skin and Venereal Diseases, Medical School, University of Ioannina, S. Niarchou Av., University Campus, 45110 Ioannina, Greece.
| | | | | | | | | |
Collapse
|
23
|
Lewis J, Filler R, Smith DA, Golubets K, Girardi M. The contribution of Langerhans cells to cutaneous malignancy. Trends Immunol 2010; 31:460-6. [PMID: 21071271 DOI: 10.1016/j.it.2010.10.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2010] [Revised: 10/05/2010] [Accepted: 10/06/2010] [Indexed: 01/08/2023]
Abstract
The skin is at the forefront of environmental exposures, such as ultraviolet radiation and a myriad of chemicals, and is at risk for malignant transformation. The skin is a highly responsive immunological organ that contains a unique population of immature intraepidermal dendritic cells (DCs) called Langerhans cells (LCs). Although LCs show morphological and migratory changes in response to epidermal perturbation, and can function as antigen-presenting cells to activate T cells, their role in carcinogenesis is unknown. Here we review recent studies that have provided clues to the potential roles that LCs might play in the pathogenesis of skin cancer, beyond their stimulation or regulation of adaptive immunity. Understanding this role of LCs might provide new perspectives on the relevance of DC populations that are resident within other epithelial tissues for cancer.
Collapse
Affiliation(s)
- Julia Lewis
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut 06511, USA
| | | | | | | | | |
Collapse
|
24
|
Haarmann-Stemmann T, Sendker J, Götz C, Krug N, Bothe H, Fritsche E, Proksch P, Abel J. Regulation of dioxin receptor function by different beta-carboline alkaloids. Arch Toxicol 2010; 84:619-29. [PMID: 20449727 DOI: 10.1007/s00204-010-0548-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Accepted: 04/19/2010] [Indexed: 12/13/2022]
Affiliation(s)
- Thomas Haarmann-Stemmann
- Institut für Umweltmedizinische Forschung (IUF), Heinrich-Heine-Universität Düsseldorf gGmbH, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
25
|
Laub LB, Jones BD, Powell WH. Responsiveness of a Xenopus laevis cell line to the aryl hydrocarbon receptor ligands 6-formylindolo[3,2-b]carbazole (FICZ) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Chem Biol Interact 2010; 183:202-11. [PMID: 19799885 DOI: 10.1016/j.cbi.2009.09.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 09/18/2009] [Accepted: 09/22/2009] [Indexed: 11/26/2022]
Abstract
The aryl hydrocarbon receptor (AHR) mediates the toxic effects of environmental contaminants, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Frogs are very insensitive to TCDD toxicity, and AHRs from Xenopus laevis (African clawed frog) bind TCDD with >20-fold lower affinity than mouse AHR(b-1). Frog AHRs may nonetheless be highly responsive to structurally distinct compounds, especially putative endogenous ligands. We sought to determine the responsiveness of an X. laevis cell line, XLK-WG, to the candidate endogenous AHR ligand 6-formylindolo[3,2-b]carbazole (FICZ), a tryptophan photoproduct that exhibits high potency in mammalian systems. FICZ readily induced mRNAs for CYP1A6 and CYP1A7. Cells exposed to FICZ for 3h expressed up to 5-fold greater quantities of CYP1A6/7 mRNAs than those exposed for 24h, suggesting FICZ is metabolized following rapid enzyme induction. FICZ appeared more potent than TCDD. Following a 3-h exposure, the EC(50) for CYP1A6 mRNA induction by FICZ was approximately 6nM, while the TCDD response was greater than 174nM. These potencies were lower than those determined for mouse hepatoma cells (Hepa1c1c7; EC(50)= approximately 0.06nM each). The difference in ligand potency between cell lines was confirmed by induction of ethoxyresorufin-O-deethylase (EROD) activity. mRNA from XLK-WG cells treated with 100nM FICZ, 100nM TCDD, or vehicle was also analyzed on expression microarrays. FICZ altered the expression of 105 more transcripts than TCDD, and common targets were altered more dramatically by FICZ. Overall, these studies demonstrate that although FICZ is a less potent CYP1A inducer in frog cells than in mouse cells, the reduction is much less than for TCDD. Relative conservation of the FICZ response in a TCDD-insensitive species suggests its physiological importance as an AHR ligand.
Collapse
Affiliation(s)
- Leo B Laub
- Biology Department, Kenyon College, 302A College Park St., Gambier, OH 43022, United States
| | | | | |
Collapse
|
26
|
Muthusamy V, Piva TJ. The UV response of the skin: a review of the MAPK, NFkappaB and TNFalpha signal transduction pathways. Arch Dermatol Res 2009; 302:5-17. [PMID: 19756672 DOI: 10.1007/s00403-009-0994-y] [Citation(s) in RCA: 192] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Revised: 08/19/2009] [Accepted: 08/21/2009] [Indexed: 10/20/2022]
Abstract
The sun emits different types of ultraviolet (UV) light. Our skin is a natural target of UV radiation which is involved in vitamin D3 production in our body. UV radiation at high doses is an environmental carcinogen which can elicit skin damage as well as inducing skin cancer. It can mediate inflammatory and immunological reactions through activation of receptors, DNA/RNA damage and production of reactive oxygen species. It is also involved in the release of pro-inflammatory cytokines, of which TNFalpha has been implicated in tumorigenic activities. In order to mediate its effects, UV radiation is known to activate multiple signalling cascades such as the p38 MAPK, Jun N-terminal kinase, extracellular signal-regulated kinase 1/2 and NFkappaB pathways in skin cells. The role each of these pathways plays in mediating the release of cytokines such as TNFalpha remains to be fully characterized. Once the function of these pathways is known, this information may provide for the formulation of therapy which will prevent the release of immunosuppressive cytokines resulting in a reduction in skin cancer formation.
Collapse
Affiliation(s)
- Visalini Muthusamy
- School of Medical Sciences, RMIT University, PO Box 71, Bundoora, VIC 3083, Australia.
| | | |
Collapse
|
27
|
Rundhaug JE, Fischer SM. Cyclo-oxygenase-2 Plays a Critical Role in UV-induced Skin Carcinogenesis. Photochem Photobiol 2008; 84:322-9. [DOI: 10.1111/j.1751-1097.2007.00261.x] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
|