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Okadaic acid activates Wnt/β-catenin-signaling in human HepaRG cells. Arch Toxicol 2019; 93:1927-1939. [PMID: 31115591 DOI: 10.1007/s00204-019-02489-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 05/16/2019] [Indexed: 12/13/2022]
Abstract
The lipophilic phycotoxin okadaic acid (OA) occurs in the fatty tissue and hepatopancreas of filter-feeding shellfish. The compound provokes the diarrhetic shellfish poisoning (DSP) syndrome after intake of seafood contaminated with high levels of the DSP toxin. In animal experiments, long-term exposure to OA is associated with an elevated risk for tumor formation in different organs including the liver. Although OA is a known inhibitor of the serine/threonine protein phosphatase 2A, the mechanisms behind OA-induced carcinogenesis are not fully understood. Here, we investigated the influence of OA on the β-catenin-dependent Wnt-signaling pathway, addressing a major oncogenic pathway relevant for tumor development. We analyzed OA-mediated effects on β-catenin and its biological function, cellular localization, post-translational modifications, and target gene expression in human HepaRG hepatocarcinoma cells treated with non-cytotoxic concentrations up to 50 nM. We detected concentration- and time-dependent effects of OA on the phosphorylation state, cellular redistribution as well as on the amount of transcriptionally active β-catenin. These findings were confirmed by quantitative live-cell imaging of U2OS cells stably expressing a green fluorescent chromobody which specifically recognize hypophosphorylated β-catenin. Finally, we demonstrated that nuclear translocation of β-catenin mediated by non-cytotoxic OA concentrations results in an upregulation of Wnt-target genes. In conclusion, our results show a significant induction of the canonical Wnt/β-catenin-signaling pathway by OA in human liver cells. Our data contribute to a better understanding of the molecular mechanisms underlying OA-induced carcinogenesis.
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Dietrich J, Grass I, Günzel D, Herek S, Braeuning A, Lampen A, Hessel-Pras S. The marine biotoxin okadaic acid affects intestinal tight junction proteins in human intestinal cells. Toxicol In Vitro 2019; 58:150-160. [PMID: 30926360 DOI: 10.1016/j.tiv.2019.03.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 03/20/2019] [Accepted: 03/25/2019] [Indexed: 12/17/2022]
Abstract
Okadaic acid (OA) is a lipophilic phycotoxin that accumulates in the hepatopancreas and fatty tissue of shellfish. Consumption of highly OA-contaminated seafood leads to diarrhetic shellfish poisoning which provokes severe gastrointestinal symptoms associated with a disruption of the intestinal epithelium. Since the molecular mechanisms leading to intestinal barrier disruption are not fully elucidated, we investigated the influence of OA on intestinal tight junction proteins (TJPs) in differentiated Caco-2 cells. We found a concentration- and time-dependent deregulation of genes encoding for intestinal TJPs of the claudin family, occludin, as well as zonula occludens (ZO) 1 and 2. Immunofluorescence staining showed concentration-dependent effects on the structural organization of TJPs already after treatment with a subtoxic but human-relevant concentration of OA. In addition, changes in the structural organization of cytoskeletal F-actin as well as its associated protein ZO-1 were observed. In summary, we demonstrated effects of OA on TJPs in intestinal Caco-2 cells. TJP expressions were affected after treatment with food-relevant OA concentrations. These results might explain the high potential of OA to disrupt the intestinal barrier in vivo as its first target. Thereby the present data contribute to a better understanding of the OA-dependent induction of molecular effects within the intestinal epithelium.
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Affiliation(s)
- Jessica Dietrich
- German Federal Institute for Risk Assessment, Department of Food Safety, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - Irina Grass
- German Federal Institute for Risk Assessment, Department of Food Safety, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - Dorothee Günzel
- Institute of Clinical Physiology, Campus Benjamin Franklin, Charité Berlin, Hindenburgdamm 30, 12203 Berlin, Germany
| | - Saadet Herek
- German Federal Institute for Risk Assessment, Department of Food Safety, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - Albert Braeuning
- German Federal Institute for Risk Assessment, Department of Food Safety, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - Alfonso Lampen
- German Federal Institute for Risk Assessment, Department of Food Safety, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - Stefanie Hessel-Pras
- German Federal Institute for Risk Assessment, Department of Food Safety, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany.
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Comparative analysis of the cytotoxic effects of okadaic acid-group toxins on human intestinal cell lines. Mar Drugs 2014; 12:4616-34. [PMID: 25196936 PMCID: PMC4145334 DOI: 10.3390/md12084616] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 08/12/2014] [Accepted: 08/13/2014] [Indexed: 11/16/2022] Open
Abstract
The phycotoxin, okadaic acid (OA) and dinophysistoxin 1 and 2 (DTX-1 and -2) are protein phosphatase PP2A and PP1 inhibitors involved in diarrhetic shellfish poisoning (DSP). Data on the toxicity of the OA-group toxins show some differences with respect to the in vivo acute toxicity between the toxin members. In order to investigate whether OA and congeners DTX-1 and -2 may induce different mechanisms of action during acute toxicity on the human intestine, we compared their toxicological effects in two in vitro intestinal cell models: the colorectal adenocarcinoma cell line, Caco-2, and the intestinal muco-secreting cell line, HT29-MTX. Using a high content analysis approach, we evaluated various cytotoxicity parameters, including apoptosis (caspase-3 activation), DNA damage (phosphorylation of histone H2AX), inflammation (translocation of NF-κB) and cell proliferation (Ki-67 production). Investigation of the kinetics of the cellular responses demonstrated that the three toxins induced a pro-inflammatory response followed by cell cycle disruption in both cell lines, leading to apoptosis. Our results demonstrate that the three toxins induce similar effects, as no major differences in the cytotoxic responses could be detected. However DTX-1 induced cytotoxic effects at five-fold lower concentrations than for OA and DTX-2.
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Ehlers A, These A, Hessel S, Preiss-Weigert A, Lampen A. Active elimination of the marine biotoxin okadaic acid by P-glycoprotein through an in vitro gastrointestinal barrier. Toxicol Lett 2014; 225:311-7. [DOI: 10.1016/j.toxlet.2013.12.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 12/18/2013] [Accepted: 12/19/2013] [Indexed: 10/25/2022]
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Kittler K, Fessard V, Maul R, Hurtaud-Pessel D. CYP3A4 activity reduces the cytotoxic effects of okadaic acid in HepaRG cells. Arch Toxicol 2014; 88:1519-26. [DOI: 10.1007/s00204-014-1206-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 01/20/2014] [Indexed: 11/29/2022]
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Munday R, Reeve J. Risk assessment of shellfish toxins. Toxins (Basel) 2013; 5:2109-37. [PMID: 24226039 PMCID: PMC3847717 DOI: 10.3390/toxins5112109] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 10/23/2013] [Accepted: 10/30/2013] [Indexed: 01/24/2023] Open
Abstract
Complex secondary metabolites, some of which are highly toxic to mammals, are produced by many marine organisms. Some of these organisms are important food sources for marine animals and, when ingested, the toxins that they produce may be absorbed and stored in the tissues of the predators, which then become toxic to animals higher up the food chain. This is a particular problem with shellfish, and many cases of poisoning are reported in shellfish consumers each year. At present, there is no practicable means of preventing uptake of the toxins by shellfish or of removing them after harvesting. Assessment of the risk posed by such toxins is therefore required in order to determine levels that are unlikely to cause adverse effects in humans and to permit the establishment of regulatory limits in shellfish for human consumption. In the present review, the basic principles of risk assessment are described, and the progress made toward robust risk assessment of seafood toxins is discussed. While good progress has been made, it is clear that further toxicological studies are required before this goal is fully achieved.
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Affiliation(s)
- Rex Munday
- AgResearch Ltd, Ruakura Research Centre, Private Bag 3123, Hamilton, New Zealand
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +64-7-838-5138; Fax: +64-7-838-5012
| | - John Reeve
- Ministry of Primary Industries, PO Box 2526, Wellington, New Zealand; E-Mail:
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Oral toxicity of okadaic acid in mice: study of lethality, organ damage, distribution and effects on detoxifying gene expression. Toxins (Basel) 2013; 5:2093-108. [PMID: 24217398 PMCID: PMC3847716 DOI: 10.3390/toxins5112093] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 10/15/2013] [Accepted: 11/05/2013] [Indexed: 02/07/2023] Open
Abstract
In vivo, after administration by gavage to mice and rats, okadaic acid has been reported to produce lesions in liver, small intestine and forestomach. Because several reports differ in the damage detected in different organs, and on okadaic acid distribution after consumption, we determined the toxicity of this compound after oral administration to mice. After 24 hours, histopathological examination showed necrotic foci and lipid vacuoles in the livers of intoxicated animals. By immunohistochemical analysis, we detected this toxin in the liver and kidneys of intoxicated animals. Okadaic acid induces oxidative stress and can be activated in vitro into reactive compounds by the post-mitochondrial S9 fraction, so we studied the okadaic effect on the gene expression of antioxidant and phase II detoxifying enzymes in liver. We observed a downregulation in the expression of these enzymes and a reduction of protein expression of catalase and superoxide dismutase 1 in intoxicated animals.
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Valdiglesias V, Prego-Faraldo MV, Pásaro E, Méndez J, Laffon B. Okadaic acid: more than a diarrheic toxin. Mar Drugs 2013; 11:4328-49. [PMID: 24184795 PMCID: PMC3853731 DOI: 10.3390/md11114328] [Citation(s) in RCA: 161] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 10/08/2013] [Accepted: 10/23/2013] [Indexed: 01/04/2023] Open
Abstract
Okadaic acid (OA) is one of the most frequent and worldwide distributed marine toxins. It is easily accumulated by shellfish, mainly bivalve mollusks and fish, and, subsequently, can be consumed by humans causing alimentary intoxications. OA is the main representative diarrheic shellfish poisoning (DSP) toxin and its ingestion induces gastrointestinal symptoms, although it is not considered lethal. At the molecular level, OA is a specific inhibitor of several types of serine/threonine protein phosphatases and a tumor promoter in animal carcinogenesis experiments. In the last few decades, the potential toxic effects of OA, beyond its role as a DSP toxin, have been investigated in a number of studies. Alterations in DNA and cellular components, as well as effects on immune and nervous system, and even on embryonic development, have been increasingly reported. In this manuscript, results from all these studies are compiled and reviewed to clarify the role of this toxin not only as a DSP inductor but also as cause of alterations at the cellular and molecular levels, and to highlight the relevance of biomonitoring its effects on human health. Despite further investigations are required to elucidate OA mechanisms of action, toxicokinetics, and harmful effects, there are enough evidences illustrating its toxicity, not related to DSP induction, and, consequently, supporting a revision of the current regulation on OA levels in food.
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Affiliation(s)
- Vanessa Valdiglesias
- Toxicology Unit, Department of Psychobiology, University of A Coruña, A Coruña E15071, Spain; E-Mails: (E.P.); (B.L.)
- Department of Cellular and Molecular Biology, University of A Coruna, A Coruña E15071, Spain; E-Mails: (M.V.P.-F.); (J.M.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +34-981167000; Fax: +34-981167172
| | - María Verónica Prego-Faraldo
- Department of Cellular and Molecular Biology, University of A Coruna, A Coruña E15071, Spain; E-Mails: (M.V.P.-F.); (J.M.)
| | - Eduardo Pásaro
- Toxicology Unit, Department of Psychobiology, University of A Coruña, A Coruña E15071, Spain; E-Mails: (E.P.); (B.L.)
| | - Josefina Méndez
- Department of Cellular and Molecular Biology, University of A Coruna, A Coruña E15071, Spain; E-Mails: (M.V.P.-F.); (J.M.)
| | - Blanca Laffon
- Toxicology Unit, Department of Psychobiology, University of A Coruña, A Coruña E15071, Spain; E-Mails: (E.P.); (B.L.)
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Prego-Faraldo MV, Valdiglesias V, Méndez J, Eirín-López JM. Okadaic acid meet and greet: an insight into detection methods, response strategies and genotoxic effects in marine invertebrates. Mar Drugs 2013; 11:2829-45. [PMID: 23939476 PMCID: PMC3766868 DOI: 10.3390/md11082829] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 07/30/2013] [Accepted: 08/01/2013] [Indexed: 12/24/2022] Open
Abstract
Harmful Algal Blooms (HABs) constitute one of the most important sources of contamination in the oceans, producing high concentrations of potentially harmful biotoxins that are accumulated across the food chains. One such biotoxin, Okadaic Acid (OA), is produced by marine dinoflagellates and subsequently accumulated within the tissues of filtering marine organisms feeding on HABs, rapidly spreading to their predators in the food chain and eventually reaching human consumers causing Diarrhetic Shellfish Poisoning (DSP) syndrome. While numerous studies have thoroughly evaluated the effects of OA in mammals, the attention drawn to marine organisms in this regard has been scarce, even though they constitute primary targets for this biotoxin. With this in mind, the present work aimed to provide a timely and comprehensive insight into the current literature on the effect of OA in marine invertebrates, along with the strategies developed by these organisms to respond to its toxic effect together with the most important methods and techniques used for OA detection and evaluation.
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Affiliation(s)
- María Verónica Prego-Faraldo
- XENOMAR Group, Department of Cellular and Molecular Biology, University of A Coruna, E15071 A Coruña, Spain; E-Mails: (M.V.P.-F.); (J.M.)
| | - Vanessa Valdiglesias
- Toxicology Unit, Department of Psychobiology, University of A Coruña, E15071 A Coruña, Spain; E-Mail:
| | - Josefina Méndez
- XENOMAR Group, Department of Cellular and Molecular Biology, University of A Coruna, E15071 A Coruña, Spain; E-Mails: (M.V.P.-F.); (J.M.)
| | - José M. Eirín-López
- XENOMAR Group, Department of Cellular and Molecular Biology, University of A Coruna, E15071 A Coruña, Spain; E-Mails: (M.V.P.-F.); (J.M.)
- Chromatin Structure and Evolution (CHROMEVOL) Group, Department of Biological Sciences, Florida International University, North Miami, FL 33181, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +34-981-167-000; Fax: +34-981-167-065
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Valdiglesias V, Fernández-Tajes J, Méndez J, Pásaro E, Laffon B. The marine toxin okadaic acid induces alterations in the expression level of cancer-related genes in human neuronal cells. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2013; 92:303-311. [PMID: 23561263 DOI: 10.1016/j.ecoenv.2013.03.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 03/04/2013] [Accepted: 03/05/2013] [Indexed: 06/02/2023]
Abstract
Okadaic acid (OA) is one of the most common and highly distributed marine toxins. It can be accumulated in several molluscs and other marine organisms and cause acute gastrointestinal symptoms after oral consumption by humans, called diarrheic shellfish poisoning. However other toxic effects beyond these gastrointestinal symptoms were also reported. Thus, OA was found to induce important chromosomal abnormalities and other genetic injuries that can lead to severe pathologies, including cancer. Furthermore, the relationship between OA and carcinogenic processes has been previously demonstrated in in vivo studies with rodents, and also suggested in human epidemiological studies. In this context, further research is required to better understand the underlying mechanisms of OA-related tumourigenesis. In a previous study, we identified 247 genes differentially expressed in SHSY5Y neuroblastoma cells exposed to 100nM OA at different times (3, 24 and 48h) by means of suppression subtractive hybridization. These genes were involved in relevant cell functions such as signal transduction, cell cycle, metabolism, and transcription and translation processes. However, due to the high potential percentage of false positives that may be obtained by this approach, results from SSH are recommended to be analyzed by an independent method. In the present study, we selected ten genes related to cancer initiation or progression, directly or indirectly, for further quantitative PCR analysis (ANAPC13, PTTG1, CALM2, CLU, HN1, MALAT1, MAPRE2, MLLT11, SGA-81M and TAX1BP1). Results obtained showed important alterations in the expression patterns of all the genes evaluated at one or more treatment times, providing, for the first time, a possible explanation at the molecular level of the potential relationship between the consumption of OA-contaminated shellfish and the incidence of different cancers in humans. Nevertheless, given the complexity of this process, more exhaustive studies are required before drawing any final conclusion.
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Affiliation(s)
- Vanessa Valdiglesias
- Toxicology Unit, Psychobiology Department, University of A Coruña, Edificio de Servicios Centrales de Investigación, Campus Elviña s/n, 15071 A Coruña, Spain
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Prado-Alvarez M, Flórez-Barrós F, Sexto-Iglesias A, Méndez J, Fernandez-Tajes J. Effects of okadaic acid on haemocytes from Mytilus galloprovincialis: a comparison between field and laboratory studies. MARINE ENVIRONMENTAL RESEARCH 2012; 81:90-93. [PMID: 23000349 DOI: 10.1016/j.marenvres.2012.08.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 08/29/2012] [Accepted: 08/31/2012] [Indexed: 06/01/2023]
Abstract
Individuals of Mytilus galloprovincialis, contaminated with Diarrheic Shellfish Poisoning (DSP) toxins, were studied with the aim to correlate the okadaic acid (OA) body burden and the percentage of damaged haemocytes by quantifying annexin V positive cells by flow cytometry. Results showed less percentage of damaged haemocytes in high OA contaminated samples. These data were compared with results of in vitro assays of mussel haemocytes exposed to increased concentrations of OA. Similarly, haemocytes exposed to the most concentrated OA solution were less damaged.
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Affiliation(s)
- Maria Prado-Alvarez
- Department of Cell and Molecular Biology, Campus A Zapateira s/n, University of A Coruña, A Coruña, Spain
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Liu L, Guo F, Crain S, Quilliam MA, Wang X, Rein KS. The structures of three metabolites of the algal hepatotoxin okadaic acid produced by oxidation with human cytochrome P450. Bioorg Med Chem 2012; 20:3742-5. [PMID: 22608922 DOI: 10.1016/j.bmc.2012.04.046] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 04/16/2012] [Accepted: 04/24/2012] [Indexed: 11/25/2022]
Abstract
Four metabolites of okadaic acid were generated by incubation with human recombinant cytochrome P450 3A4. The structures of two of the four metabolites have been determined by MS/MS experiments and 1D and 2D NMR methods using 94 and 133 μg of each metabolite. The structure of a third metabolite was determined by oxidation to a metabolite of known structure. Like okadaic acid, the metabolites are inhibitors of protein phosphatase PP2A. Although one of the metabolites does have an α,β unsaturated carbonyl with the potential to form adducts with an active site cysteine, all of the metabolites are reversible inhibitors of PP2A.
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Affiliation(s)
- Li Liu
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, USA
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Fieber LA, Greer JB, Guo F, Crawford DC, Rein KS. GENE EXPRESSION PROFILING OF HUMAN LIVER CARCINOMA (HepG2) CELLS EXPOSED TO THE MARINE TOXIN OKADAIC ACID. TOXICOLOGICAL AND ENVIRONMENTAL CHEMISTRY 2012; 24:1805-1821. [PMID: 23172983 PMCID: PMC3500632 DOI: 10.1080/02772248.2012.730199] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The marine toxin, okadaic acid (OA) is produced by dinoflagellates of the genera Prorocentrum and Dinophysis and is the causative agent of the syndrome known as diarrheic shellfish poisoning (DSP). In addition, OA acts as both a tumor promoter, attributed to OA-induced inhibition of protein phosphatases as well as an inducer of apoptosis. To better understand the potentially divergent toxicological profile of OA, the concentration dependent cytotoxicity and alterations in gene expression on the human liver tumor cell line HepG2 upon OA exposure were determined using RNA microarrays, DNA fragmentation, and cell proliferation assays as well as determinations of cell detachment and cell death in different concentrations of OA. mRNA expression was quantified for approximately 15,000 genes. Cell attachment and proliferation were both negatively correlated with OA concentration. Detached cells displayed necrotic DNA signatures but apoptosis also was broadly observed. Data suggest that OA has a concentration dependent effect on cell cycle, which might explain the divergent effects that at low concentration OA stimulates genes involved in the cell cycle and at high concentrations it stimulates apoptosis.
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Affiliation(s)
- Lynne A. Fieber
- Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Cswy, Miami, FL, USA 33149
| | - Justin B. Greer
- Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Cswy, Miami, FL, USA 33149
| | - Fujiang Guo
- Department of Chemistry and Biochemistry, 11200 SW 8 St, Florida International University, Miami, FL, USA33199
| | - Douglas C. Crawford
- Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Cswy, Miami, FL, USA 33149
| | - Kathleen S. Rein
- Department of Chemistry and Biochemistry, 11200 SW 8 St, Florida International University, Miami, FL, USA33199
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Ehlers A, Scholz J, These A, Hessel S, Preiss-Weigert A, Lampen A. Analysis of the passage of the marine biotoxin okadaic acid through an in vitro human gut barrier. Toxicology 2011; 279:196-202. [DOI: 10.1016/j.tox.2010.11.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 11/03/2010] [Accepted: 11/09/2010] [Indexed: 10/18/2022]
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Valdiglesias V, Laffon B, Pásaro E, Méndez J. Evaluation of okadaic acid-induced genotoxicity in human cells using the micronucleus test and γH2AX analysis. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2011; 74:980-992. [PMID: 21707423 DOI: 10.1080/15287394.2011.582026] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Marine algal blooms have become a public health concern due to increasing frequency in the environment and severity of exposure consequences. Human intoxications produced by phycotoxins occur globally through consumption of marine fish products containing bioaccumulated toxins. Okadaic acid (OA) is the main representative of diarrheic shellfish poisoning (DSP) toxin. OA was found to inhibit protein phosphatases and to produce oxidative damage, as well as to disturb different cellular functions including cell cycle, gene expression, and DNA repair mechanisms. The aim of this study was to determine whether OA induced genotoxicity by using a micronucleus (MN) test and γH2AX analysis, and to elucidate the underlying mechanisms. Human peripheral blood leukocytes, neuroblastoma cells (SHSY5Y), and hepatoma cells (HepG2) were treated with a range of OA concentrations in the presence and absence of S9 fraction. MN induction was observed in leukocytes at all concentrations tested, and in SHSY5Y and HepG2 cells only at the highest concentration (1000 nM). In contrast, γH2AX analysis was only positive for HepG2 cells. Taking together these data, in addition to the comet assay results obtained in a previous study in this issue, OA was found to exert a either a clastogenic or aneugenic effect dependent upon the cell types examined.
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Affiliation(s)
- Vanessa Valdiglesias
- Toxicology Unit, Department of Psychobiology, University of A Coruña, A Coruña, Spain.
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16
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Guo F, An T, Rein KS. The algal hepatoxoxin okadaic acid is a substrate for human cytochromes CYP3A4 and CYP3A5. Toxicon 2009; 55:325-32. [PMID: 19699225 DOI: 10.1016/j.toxicon.2009.08.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Revised: 08/11/2009] [Accepted: 08/14/2009] [Indexed: 11/28/2022]
Abstract
The hepatotoxin okadaic acid (OA) was incubated with nine human recombinant cytochrome P450s (1A1, 1A2, 2C8, 2C9, 2C19, 2D6, 2E1, 3A4 and 3A5). Both CYP3A4 and CYP3A5 converted OA to a mixture of the same four metabolites, but incubation with CYP3A4 resulted in higher levels of conversion. Michaelis-Menten parameters, K(m) (73.4 microM) and V(max) (7.23 nmol of metabolitesnmol(-1)min(-1)) for CYP3A4 were calculated by analyzing double-reciprocal plots. LC-MS(n) analysis and chemical interconversion indicate that metabolites 2 and 3 are the 11S-hydroxy and 11R-hydroxy okadaic acid respectively, while metabolite 4 is 11-oxo okadaic acid. LC-MS(n) analysis of metabolite 1 shows a molecular ion which corresponds to an addition of 16 amu to OA, also suggesting hydroxylation, but the specific site has not been identified. The same four metabolites were produced upon incubation of okadaic acid with pooled human liver microsomes. This transformation could be completely inhibited with ketokonazole, and inhibitor of the CYP3A family of enzymes. The metabolites were determined to be only slightly less potent inhibitors of serine threonine protein phosphatase 2A (PP2A) when compared to OA. As PP2A is the principle molecular target for OA, these oxidative transformations may not effectively detoxify OA.
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Affiliation(s)
- Fujiang Guo
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th St., Miami, FL 33199, USA
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Hashizume T, Yoshitomi S, Asahi S, Matsumura S, Chatani F, Oda H. In vitro micronucleus test in HepG2 transformants expressing a series of human cytochrome P450 isoforms with chemicals requiring metabolic activation. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2009; 677:1-7. [DOI: 10.1016/j.mrgentox.2009.03.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2008] [Revised: 03/12/2009] [Accepted: 03/29/2009] [Indexed: 10/20/2022]
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Souid-Mensi G, Moukha S, Mobio TA, Maaroufi K, Creppy EE. The cytotoxicity and genotoxicity of okadaic acid are cell-line dependent. Toxicon 2008; 51:1338-44. [DOI: 10.1016/j.toxicon.2008.03.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Revised: 02/25/2008] [Accepted: 03/03/2008] [Indexed: 11/26/2022]
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Souid-Mensi G, Moukha S, Maaroufi K, Creppy EE. Combined cytotoxicity and genotoxicity of a marine toxin and seafood contaminant metal ions (chromium and cadmium). ENVIRONMENTAL TOXICOLOGY 2008; 23:1-8. [PMID: 18214935 DOI: 10.1002/tox.20304] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Algal bloom with consequent production of marine toxins contaminating bivalves is increasing in costal regions worldwide because of sea water quality worsening. Contamination of seafood by diarrheic shellfish poisoning toxins (DSP) together with metals is frequently reported, a phenomenon not fully explained yet. In this context, metal ions were assayed in clams collected from the banned area of Boughrara, Tunisia, contaminated by Gymnodinium and other algae such as Dinophysis sp, accumulated by these bivalves. The presence of toxic metals ions such as Chromium (Cr) and Cadmium (Cd) in meat, shells, and water released by the clams prompted us to experiment in Caco-2 intestinal cell line toxic effects of these heavy metals ions in combination with okadaic acid, one DSP present in clams to assess the potential global toxicity. Cr and Cd produce additive effects in (i) reactive oxygen species production, (ii) cytotoxicity as assessed by the mitochondrial activity testing method (MTT test), and (iii) DNA lesions evaluated by agarose gel electrophoresis and acridine orange staining. Exaggerated DNA fragmentation is observed, suggesting an overloading of repair capacity of Caco-2 cells. The apoptosis suggested by a DNA fragment sizing (180-200 bp) in agarose gel and mechanisms underlying these additive effects in Caco-2 cells still need to be more comprehensively explained.
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Affiliation(s)
- Ghada Souid-Mensi
- University Victor Segalen Bordeaux, Faculty of Pharmacy, Laboratory of Toxicology and Applied Hygiene, 146 rue Léo-Saignat, 33076, Bordeaux, France
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Manerio E, Rodas VL, Costas E, Hernandez JM. Shellfish consumption: a major risk factor for colorectal cancer. Med Hypotheses 2007; 70:409-12. [PMID: 17606330 DOI: 10.1016/j.mehy.2007.03.041] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2007] [Accepted: 03/27/2007] [Indexed: 11/23/2022]
Abstract
In the last decades, relevant efforts have been made to reduce the cancer incidence in the European Union. The prevention programmes against cancer have obtained satisfactory results except for colorectal cancer (CRC). Identification of risk factors is primordial to plan preventive strategies for CRC. We hypothesize that shellfish consumption is increasing CRC incidence. DSP toxins, present in some seafood products, seem to behave like tumour agents. There are no relevant studies on real health-risk of consuming DSP toxins, just some experimental and ecological evidence. Preventive interventions for reducing CRC risk must be approached through the collaboration of governmental, health and environmental sectors as a single regulatory agency. Sometimes, shellfish accumulates diarrhetic shellfish poisoning (DSP) toxins (i.e. okadaic acid and its derivatives) which provoke a gastrointestinal illness (DSP syndrome). Furthermore, DSP toxins are tumour promoters that could increase CRC risk. The current regulation about level of DSP toxins in shellfish meat is only centred on reduction of the gastrointestinal symptoms. Unfortunately, legal levels of DSP toxins in shellfish are enough to increase CRC risk. A review of legislation on DSP toxins is urgent.
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Affiliation(s)
- Emilia Manerio
- Genética, Facultad de Veterinaria, UCM, 28040 Madrid, Spain
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Carvalho PS, Catia R, Moukha S, Matias WG, Creppy EE. Comparative study of Domoic Acid and Okadaic Acid induced-chromosomal abnormalities in the Caco-2 cell line. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2007; 3:4-10. [PMID: 16823071 PMCID: PMC3785674 DOI: 10.3390/ijerph2006030001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Okadaic Acid (OA) the major diarrheic shellfish poisoning (DSP) toxin is known as a tumor promoter and seems likely implicated in the genesis of digestive cancer. Little is known regarding genotoxicity and carcinogenicity of Domoic Acid (DA), the major Amnesic Shellfish Poisoning (ASP) toxin. Both OA and DA occur in seafood and are of human health concerns. Micronuclei (MN) arise from abnormalities in nuclear division during mitosis due to a failure of the mitotic spindle or by complex chromosomal configurations that pose problems during anaphase. In order to evaluate the ability of okadaic acid (OA) and domoic acid (DA) to induce DNA damage we performed the micronucleus assay using the Caco-2 cell line. To discriminate between a clastogenic or aneugenic effect of OA and DA, the micronucleus assay was conducted by cytokinesis-block micronucleus assay using cytochalasin B with Giemsa staining and/or acridine orange staining, in parallel to fluorescence in situ hybridization (FISH) using a concentrated human pan-centromeric chromosome paint probe. Our results showed that OA and DA significantly increased the frequency of MN in Caco-2 cells. The MN caused by OA are found in mononucleated cells and binucleated cells, whereas those caused by DA are mainly in binucleated cells. The results of FISH analysis showed that OA induced centromere-positive micronuclei and DA increased the percentage of MN without a centromeric signal. In conclusion, both OA and DA bear mutagenic potential as revealed in Caco-2 cells by induction of MN formation. Moreover, OA induced whole chromosome loss suggesting a specific aneugenic potential, whereas DA seems simply clastogenic. At present, one cannot rule out possible DNA damage of intestinal cells if concentrations studied are reached in vivo, since this may happen with concentrations of toxins just below regulatory limits in case of frequent consumption of contaminated shell fishes.
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Affiliation(s)
- Pinto-Silva Carvalho
- Department of Environmental Engineering - Toxicological Laboratory of the Federal University of Santa Catarina, Brazil Campus Universitário, Trindade, 88040-900,
Brazil
| | - R. Catia
- Department of Environmental Engineering - Toxicological Laboratory of the Federal University of Santa Catarina, Brazil Campus Universitário, Trindade, 88040-900,
Brazil
- Unit of Mycology and Food Safety, National Institute of the Agronomic Research - INRA - Villenave d’Ornon,
France
| | - Serge Moukha
- Unit of Mycology and Food Safety, National Institute of the Agronomic Research - INRA - Villenave d’Ornon,
France
| | - William G. Matias
- Department of Environmental Engineering - Toxicological Laboratory of the Federal University of Santa Catarina, Brazil Campus Universitário, Trindade, 88040-900,
Brazil
| | - Edmond E. Creppy
- Department of Pharmaceutical Sciences - Toxicological Laboratory of the University of Bordeaux 2,
France
- Correspondence to Dr. Edmond E. Creppy.
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Le Hégarat L, Jacquin AG, Bazin E, Fessard V. Genotoxicity of the marine toxin okadaic acid, in human Caco-2 cells and in mice gut cells. ENVIRONMENTAL TOXICOLOGY 2006; 21:55-64. [PMID: 16463260 DOI: 10.1002/tox.20154] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Micronucleus induction by the diarrhetic shellfish toxin okadaic acid (OA) was investigated in two intestinal models, cultured human Caco-2 cells and colon epithelial cells of mice treated in vivo. Exposure to OA for 4 and 24 h induced dose-responsive increases in the frequency of micronucleated Caco-2 cells; the minimum OA doses increasing micronucleus frequency were 20 nM for the 4 h treatment and 5 nM for the 24 h treatment. OA treatment of Caco-2 cells also resulted in dose- and time-dependent increases in mitotic arrest and multinucleated cells. Two experiments were conducted in which mice were treated with single oral gavages of 435-610 and 115-1341 microg/kg OA. In the first experiment, samples were taken 24 h after the treatment, and the frequencies of both micronucleated and mitotic gut cells were increased after treatment with 525 microg/kg OA. In the second experiment, no increases in micronucleus frequency were detected at 24, 36, or 48 h following OA doses of 230 and 115 microg/kg; however, an increase in the mitotic index was observed 36 h after a gavage with 115 microg/kg OA. In this experiment, doses higher than 230 microg/kg were rapidly lethal to the mice. Immunohistology with monoclonal OA antibodies showed that OA was distributed into the liver at all the sampling times and in the small intestine at 24 and 36 h; OA was not detected in the colon. In addition, the TUNEL assay indicated that OA induced apoptosis in mouse ileum, liver, and kidney. The results of our investigations suggest that OA is aneugenic in Caco-2 cells, whereas the in vivo data were inconclusive. Further studies should be performed in mice using intragastric doses of 230-525 microg/kg OA. Moreover, the apoptosis and cell proliferation results indicate that OA can reach organs other than colon, indicating further evaluation of the genotoxic potential of OA in these organs is warranted.
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Affiliation(s)
- Ludovic Le Hégarat
- AFSSA, Unité de Toxicologie Génétique des Contaminants Alimentaires, La Haute Marche, BP 90203, 35133 Fougères, France
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Le Hégarat L, Nesslany F, Mourot A, Marzin D, Fessard V. Lack of DNA damage induction by okadaic acid, a marine toxin, in the CHO-Hprt and the in vitro UDS assays. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2004; 564:139-47. [PMID: 15507378 DOI: 10.1016/j.mrgentox.2004.08.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2004] [Revised: 07/26/2004] [Accepted: 08/10/2004] [Indexed: 11/20/2022]
Abstract
Okadaic acid (OA) is a marine toxin produced by dinoflagellates and responsible for human intoxications. OA is a specific inhibitor of serine/threonine protein phosphatases PP1 and PP2A and a potent tumor promoter in mouse skin and rat glandular stomach. In a previous study, we demonstrated that OA induced aneuploidy in CHO-K1 cells using the cytokinesis-block micronucleus (CBMN) assay coupled to FISH and concluded that OA was not a direct mutagen. As some previous in vitro mutagenicity studies had given positive results with OA, we decided to perform two additional in vitro mutagenicity assays in accordance with the OECD guidelines: (i) the CHO/Hprt test, which provides end points about locus-specific gene mutation; (ii) the in vitro unscheduled DNA synthesis (UDS) assay in rat hepatocytes, which measures [(3)H]thymidine incorporation into DNA undergoing excision repair. In the CHO/Hprt assay, there was no significant increase in the number of mutants for doses ranging from 5 to 5000 nM in the presence or absence of rat liver S9 fraction. In the in vitro UDS assay, OA did not induce primary DNA damages in rat hepatocytes following 18 h exposure at concentrations between 1.32 and 100 nM. As OA could affect the DNA repair systems via the inhibition of protein phosphatases, its effects on the repair kinetic of 2AAF-induced DNA damage were also investigated with the UDS assay. The results showed that OA did not interact with the DNA-repair process involved in in vitro UDS in rat hepatocytes. We concluded that OA failed to induce direct DNA damage but acted principally by altering the chromosome number, which could contribute to its carcinogenic effect.
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Affiliation(s)
- Ludovic Le Hégarat
- AFSSA, Laboratoire d'Etudes et de Recherches sur les Médicaments Vétérinaires et les Désinfectants, Unité de Toxicologie Alimentaire, B.P. 90203, 35302 Fougères Cedex, France
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