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Totland MZ, Omori Y, Sørensen V, Kryeziu K, Aasen T, Brech A, Leithe E. Endocytic trafficking of connexins in cancer pathogenesis. Biochim Biophys Acta Mol Basis Dis 2023:166812. [PMID: 37454772 DOI: 10.1016/j.bbadis.2023.166812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 06/26/2023] [Accepted: 07/11/2023] [Indexed: 07/18/2023]
Abstract
Gap junctions are specialized regions of the plasma membrane containing clusters of channels that provide for the diffusion of ions and small molecules between adjacent cells. A fundamental role of gap junctions is to coordinate the functions of cells in tissues. Cancer pathogenesis is usually associated with loss of intercellular communication mediated by gap junctions, which may affect tumor growth and the response to radio- and chemotherapy. Gap junction channels consist of integral membrane proteins termed connexins. In addition to their canonical roles in cell-cell communication, connexins modulate a range of signal transduction pathways via interactions with proteins such as β-catenin, c-Src, and PTEN. Consequently, connexins can regulate cellular processes such as cell growth, migration, and differentiation through both channel-dependent and independent mechanisms. Gap junctions are dynamic plasma membrane entities, and by modulating the rate at which connexins undergo endocytosis and sorting to lysosomes for degradation, cells rapidly adjust the level of gap junctions in response to alterations in the intracellular or extracellular milieu. Current experimental evidence indicates that aberrant trafficking of connexins in the endocytic system is intrinsically involved in mediating the loss of gap junctions during carcinogenesis. This review highlights the role played by the endocytic system in controlling connexin degradation, and consequently gap junction levels, and discusses how dysregulation of these processes contributes to the loss of gap junctions during cancer development. We also discuss the therapeutic implications of aberrant endocytic trafficking of connexins in cancer cells.
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Affiliation(s)
| | - Yasufumi Omori
- Department of Molecular and Tumour Pathology, Akita University Graduate School of Medicine, Akita, Japan
| | | | | | - Trond Aasen
- Patologia Molecular Translacional, Vall d'Hebron Institut de Recerca (VHIR), Vall d'Hebron Hospital Universitari, Vall d'Hebron Barcelona Hospital Campus, Passeig Vall d'Hebron, Barcelona, Spain
| | - Andreas Brech
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway; Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway; Section for Physiology and Cell Biology, Department of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway
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2
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D'Amico D, Barone R, Di Felice V, Ances B, Prideaux B, Eugenin EA. Chronic brain damage in HIV-infected individuals under antiretroviral therapy is associated with viral reservoirs, sulfatide release, and compromised cell-to-cell communication. Cell Mol Life Sci 2023; 80:116. [PMID: 37016051 PMCID: PMC11071786 DOI: 10.1007/s00018-023-04757-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 03/11/2023] [Accepted: 03/13/2023] [Indexed: 04/06/2023]
Abstract
HIV infection has become a chronic and manageable disease due to the effective use of antiretroviral therapies (ART); however, several chronic aging-related comorbidities, including cognitive impairment, remain a major public health issue. However, these mechanisms are unknown. Here, we identified that glial and myeloid viral reservoirs are associated with local myelin damage and the release of several myelin components, including the lipid sulfatide. Soluble sulfatide compromised gap junctional communication and calcium wave coordination, essential for proper cognition. We propose that soluble sulfatide could be a potential biomarker and contributor to white matter compromise observed in HIV-infected individuals even in the current ART era.
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Affiliation(s)
- Daniela D'Amico
- Department of Neurobiology, The University of Texas Medical Branch (UTMB), Research Building 17, Fifth Floor, 11Th Street, Galveston, TX, 77555, USA
- Department of Biomedicine, Neuroscience, and Advanced Diagnostics (BiND), University of Palermo, Palermo, Italy
| | - Rosario Barone
- Department of Biomedicine, Neuroscience, and Advanced Diagnostics (BiND), University of Palermo, Palermo, Italy
| | - Valentina Di Felice
- Department of Biomedicine, Neuroscience, and Advanced Diagnostics (BiND), University of Palermo, Palermo, Italy
| | - Beau Ances
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
| | - Brendan Prideaux
- Department of Neurobiology, The University of Texas Medical Branch (UTMB), Research Building 17, Fifth Floor, 11Th Street, Galveston, TX, 77555, USA.
| | - Eliseo A Eugenin
- Department of Neurobiology, The University of Texas Medical Branch (UTMB), Research Building 17, Fifth Floor, 11Th Street, Galveston, TX, 77555, USA.
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3
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The Expression of Connexin 26 Regulates the Radiosensitivity of Hepatocellular Carcinoma Cells through a Mitogen-Activated Protein Kinases Signal Pathway. Int J Mol Sci 2022; 23:ijms232314644. [PMID: 36498978 PMCID: PMC9740976 DOI: 10.3390/ijms232314644] [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: 09/29/2022] [Revised: 11/09/2022] [Accepted: 11/21/2022] [Indexed: 11/25/2022] Open
Abstract
Connexin 26 (Cx26) is a protein that constitutes a gap junction and is widely expressed in the liver. Abnormal expression of Cx26 is one of the important mechanisms of liver cancer, and is closely related to the transmission of radiation damage signals between cells. In the present study, we investigated the radiosensitivity of hepatocellular carcinoma (HCC) cells HepG2, with low expression of Cx26, and SK-hep-1, with high expression of Cx26 after X-ray irradiation. The cell survival, micronucleus formation and protein expressions of the mitogen-activated protein kinases (MAPK) signaling pathway were detected. The expression level of Cx26 could affect the radiosensitivity of liver cancer cells by affecting the phosphorylation of p38 and ERK proteins and regulating the expression of downstream NF-κB. Cell lines with knock-out and overexpression of Cx26 were also built to confirm the findings. Our results suggested that Cx26 might play an important role in the radiosensitivity of liver cancer and could be a potential target for clinical radiotherapy of liver cancer.
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Yawer A, Sychrová E, Raška J, Babica P, Sovadinová I. Endocrine-disrupting chemicals affect sertoli TM4 cell functionality through dysregulation of gap junctional intercellular communication in vitro. Food Chem Toxicol 2022; 164:113004. [PMID: 35413382 DOI: 10.1016/j.fct.2022.113004] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/20/2022] [Accepted: 04/06/2022] [Indexed: 01/10/2023]
Abstract
The frequencies of adverse outcomes associated with male reproductive health, including infertility and testicular cancer, are increasing. These adverse trends are partially attributed to increased exposure to environmental agents such as endocrine-disrupting chemicals (EDCs). This study addresses effects on EDCs on adjacent prepubertal Sertoli TM4 cells, specifically on 1) testicular gap junctional intercellular communication (GJIC), one of the hallmarks of non-genotoxic carcinogenicity, 2) GJIC building blocks connexins (Cx), and 3) mitogen-activated protein kinases MAPKs. We selected eight representatives of EDCs: bisphenol A and organochlorine chemicals such as pesticides dichlorodiphenyltrichloroethane, lindane, methoxychlor, and vinclozolin, industrial chemical 2,2',4,4',5,5'-hexachlorobiphenyl, and components of personal care products, triclocarban and triclosan. EDCs rapidly dysregulated GJIC in Sertoli TM4 cells mainly via MAPK p38 and/or Erk1/2/pathways by the intermediate hyper- or de-phosphorylation of Cx43 (Ser368, Ser282) and translocalization of Cx43 from the plasma membrane, suggesting disturbed intracellular trafficking of Cx43 protein. Surprisingly, EDCs did not rapidly activate MAPK Erk1/2 or p38; on the contrary, TCC and TCS decreased their activity (phosphorylation). Our results indicate that EDCs might disrupt testicular homeostasis and development via testicular GJIC, junctional and non-junctional functions of Cx43 and MAPK-signalling pathways in Sertoli cells.
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Affiliation(s)
- Affiefa Yawer
- RECETOX, Faculty of Science, Masaryk University, Kotlarska 2, Brno, Czech Republic.
| | - Eliška Sychrová
- RECETOX, Faculty of Science, Masaryk University, Kotlarska 2, Brno, Czech Republic.
| | - Jan Raška
- RECETOX, Faculty of Science, Masaryk University, Kotlarska 2, Brno, Czech Republic.
| | - Pavel Babica
- RECETOX, Faculty of Science, Masaryk University, Kotlarska 2, Brno, Czech Republic.
| | - Iva Sovadinová
- RECETOX, Faculty of Science, Masaryk University, Kotlarska 2, Brno, Czech Republic.
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Applicability of Scrape Loading-Dye Transfer Assay for Non-Genotoxic Carcinogen Testing. Int J Mol Sci 2021; 22:ijms22168977. [PMID: 34445682 PMCID: PMC8396440 DOI: 10.3390/ijms22168977] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/30/2021] [Accepted: 07/31/2021] [Indexed: 12/27/2022] Open
Abstract
Dysregulation of gap junction intercellular communication (GJIC) is recognized as one of the key hallmarks for identifying non-genotoxic carcinogens (NGTxC). Currently, there is a demand for in vitro assays addressing the gap junction hallmark, which would have the potential to eventually become an integral part of an integrated approach to the testing and assessment (IATA) of NGTxC. The scrape loading-dye transfer (SL-DT) technique is a simple assay for the functional evaluation of GJIC in various in vitro cultured mammalian cells and represents an interesting candidate assay. Out of the various techniques for evaluating GJIC, the SL-DT assay has been used frequently to assess the effects of various chemicals on GJIC in toxicological and tumor promotion research. In this review, we systematically searched the existing literature to gather papers assessing GJIC using the SL-DT assay in a rat liver epithelial cell line, WB-F344, after treating with chemicals, especially environmental and food toxicants, drugs, reproductive-, cardio- and neuro-toxicants and chemical tumor promoters. We discuss findings derived from the SL-DT assay with the known knowledge about the tumor-promoting activity and carcinogenicity of the assessed chemicals to evaluate the predictive capacity of the SL-DT assay in terms of its sensitivity, specificity and accuracy for identifying carcinogens. These data represent important information with respect to the applicability of the SL-DT assay for the testing of NGTxC within the IATA framework.
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Sun M, Li Y, Qian J, Ding S, Sun M, Tan B, Zhao Y. Connexin26 Modulates the Radiosensitivity of Cutaneous Squamous Cell Carcinoma by Regulating the Activation of the MAPK/NF-κB Signaling Pathway. Front Cell Dev Biol 2021; 9:672571. [PMID: 34291047 PMCID: PMC8287175 DOI: 10.3389/fcell.2021.672571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 05/27/2021] [Indexed: 11/25/2022] Open
Abstract
Previous studies have confirmed that the gap junction protein Connexin26 (Cx26) is specifically expressed in human skin tissue. Cx26 can transmit radiation-induced damage signals. However, no study has yet reported whether Cx26 expression affects the radiosensitivity of human skin squamous cancer cells or the mechanism by which this occurs. In this study, we found that human skin squamous cell carcinoma cells (A431 cells) expressed significantly more Cx26 and were more sensitive to radiation compared to normal human keratinocytes (HaCaT cells). Knockdown of Cx26 in A431 cells (A431Cx26-/-) decreased radiosensitivity relative to control cells and altered the expression of key proteins in the MAPK and NF-κB signaling pathways. These results demonstrate that Cx26 expression might play an important role in mediating radiation damage in A431 cells and could serve as a potential target for clinical radiotherapy for cutaneous squamous cell carcinoma.
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Affiliation(s)
- Minqiong Sun
- Teaching and Research Section of Nuclear Medicine, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Yuan Li
- Teaching and Research Section of Nuclear Medicine, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Jing Qian
- Teaching and Research Section of Nuclear Medicine, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Siwei Ding
- Teaching and Research Section of Nuclear Medicine, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Mingyu Sun
- Teaching and Research Section of Nuclear Medicine, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
- Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China
| | - Bowen Tan
- Teaching and Research Section of Nuclear Medicine, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Ye Zhao
- Teaching and Research Section of Nuclear Medicine, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
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Squecco R, Pierucci F, Idrizaj E, Frati A, Lenci E, Vicenti C, Iachini MC, Martinesi M, Garella R, Baccari MC, Francini F, Meacci E. Ceramide/protein phosphatase 2A axis is engaged in gap junction impairment elicited by PCB153 in liver stem-like progenitor cells. Mol Cell Biochem 2021; 476:3111-3126. [PMID: 33837873 PMCID: PMC8263450 DOI: 10.1007/s11010-021-04135-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 03/11/2021] [Indexed: 12/22/2022]
Abstract
The widespread environmental pollutant 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153) is a non-dioxin-like toxicant. It is a potential carcinogen compound able to induce gap junction (GJ) intercellular communication impairment, probably the first non-genomic event leading to tumor promotion. Although PCBs have been known for many years, the molecular mode of PCB153 action is still unclear. Recent studies from our research group have shown that the toxicant elicits a transient modulation of connexin (Cx) 43-formed GJs in hepatic stem-like WB-F344 cells involving sphingosine 1-phosphate (S1P) path. Taking into account that other strictly related bioactive sphingolipids, such as ceramide (Cer), may have different effects from S1P, here we aim to clarify the signaling paths engaged by PCB153 in the control of GJs, focusing primarily on the role of Cer. Accordingly, we have achieved a combined biomolecular and electrophysiological analysis of GJs in cultured WB-F344 cells treated with PCB153 at different time points. We have found that the toxicant elicited a time-dependent regulation of GJs formed by different Cx isoforms, through a transient modulation of Cer/Cer kinase (CerK) axis and, in turn, of protein phosphatase 2A (PP2A). Our new findings demonstrate the existence of a specific molecular mechanism downstream to Cer, which distinctly affects the voltage-dependent and -independent GJs in liver stem-like cells, and open new opportunities for the identification of additional potential targets of these environmental toxicants.
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Affiliation(s)
- Roberta Squecco
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, Viale GB Morgagni 63, 50134, Florence, Italy
| | - Federica Pierucci
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Research unit of Molecular and Applied Biology, University of Florence, Viale GB Morgagni 50, 50134, Florence, Italy
| | - Eglantina Idrizaj
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, Viale GB Morgagni 63, 50134, Florence, Italy
| | - Alessia Frati
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Research unit of Molecular and Applied Biology, University of Florence, Viale GB Morgagni 50, 50134, Florence, Italy
| | - Elena Lenci
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Research unit of Molecular and Applied Biology, University of Florence, Viale GB Morgagni 50, 50134, Florence, Italy
| | - Catia Vicenti
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Research unit of Molecular and Applied Biology, University of Florence, Viale GB Morgagni 50, 50134, Florence, Italy
| | - Maria Chiara Iachini
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Research unit of Molecular and Applied Biology, University of Florence, Viale GB Morgagni 50, 50134, Florence, Italy
| | - Maria Martinesi
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Research unit of Molecular and Applied Biology, University of Florence, Viale GB Morgagni 50, 50134, Florence, Italy
| | - Rachele Garella
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, Viale GB Morgagni 63, 50134, Florence, Italy
| | - Maria Caterina Baccari
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, Viale GB Morgagni 63, 50134, Florence, Italy
| | - Fabio Francini
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, Viale GB Morgagni 63, 50134, Florence, Italy
| | - Elisabetta Meacci
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Research unit of Molecular and Applied Biology, University of Florence, Viale GB Morgagni 50, 50134, Florence, Italy.
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Toxicologic Evaluation for Amorphous Silica Nanoparticles: Genotoxic and Non-Genotoxic Tumor-Promoting Potential. Pharmaceutics 2020; 12:pharmaceutics12090826. [PMID: 32872498 PMCID: PMC7559769 DOI: 10.3390/pharmaceutics12090826] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 08/20/2020] [Accepted: 08/27/2020] [Indexed: 11/17/2022] Open
Abstract
Amorphous silica nanoparticles (SiO2NPs) have been widely used in medicine including targeted drug/DNA delivery, cancer therapy, and enzyme immobilization. Nevertheless, SiO2NPs should be used with caution due to safety concerns associated with unique physical and chemical characteristics. The objective of this study was to determine the effects of SiO2NPs on genotoxic and non-genotoxic mechanisms associated with abnormal gap junctional intercellular communication (GJIC) in multistage carcinogenesis. The SiO2NPs exhibited negative responses in standard genotoxicity tests including the Ames test, chromosome aberration assay, and micronucleus assay. In contrast, the SiO2NPs significantly induced DNA breakage in comet assay. Meanwhile, SiO2NPs inhibited GJIC based on the results of scrape/loading dye transfer assay for the identification of non-genotoxic tumor-promoting potential. The reduction in expression and plasma membrane localization of Cx43 was detected following SiO2NP treatment. Particularly, SiO2NP treatment increased Cx43 phosphorylation state, which was significantly attenuated by inhibitors of extracellular signal-regulated kinases 1/2 (ERK1/2) and threonine and tyrosine kinase (MEK), but not by protein kinase C (PKC) inhibitor. Taken together, in addition to a significant increase in DNA breakage, SiO2NP treatment resulted in GJIC dysregulation involved in Cx43 phosphorylation through the activation of mitogen-activated protein kinase (MAPK) signaling. Overall findings of the genotoxic and non-genotoxic carcinogenic potential of SiO2NPs provide useful toxicological information for clinical application at an appropriate dose.
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Leroy K, Pieters A, Tabernilla A, Cooreman A, Van Campenhout R, Cogliati B, Vinken M. Targeting gap junctional intercellular communication by hepatocarcinogenic compounds. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2020; 23:255-275. [PMID: 32568623 DOI: 10.1080/10937404.2020.1781010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Gap junctions in liver, as in other organs, play a critical role in tissue homeostasis. Inherently, these cellular constituents are major targets for systemic toxicity and diseases, including cancer. This review provides an overview of chemicals that compromise liver gap junctions, in particular biological toxins, organic solvents, pesticides, pharmaceuticals, peroxides, metals and phthalates. The focus in this review is placed upon the mechanistic scenarios that underlie these adverse effects. Further, the potential use of gap junctional activity as an in vitro biomarker to identify non-genotoxic hepatocarcinogenic chemicals is discussed.
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Affiliation(s)
- Kaat Leroy
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel , Brussels, Belgium
| | - Alanah Pieters
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel , Brussels, Belgium
| | - Andrés Tabernilla
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel , Brussels, Belgium
| | - Axelle Cooreman
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel , Brussels, Belgium
| | - Raf Van Campenhout
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel , Brussels, Belgium
| | - Bruno Cogliati
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, Cidade Universitária , São Paulo, Brazil
| | - Mathieu Vinken
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel , Brussels, Belgium
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Yawer A, Sychrová E, Labohá P, Raška J, Jambor T, Babica P, Sovadinová I. Endocrine-disrupting chemicals rapidly affect intercellular signaling in Leydig cells. Toxicol Appl Pharmacol 2020; 404:115177. [PMID: 32739526 DOI: 10.1016/j.taap.2020.115177] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 07/19/2020] [Accepted: 07/28/2020] [Indexed: 01/25/2023]
Abstract
A decline in male fertility possibly caused by environmental contaminants, namely endocrine-disrupting chemicals (EDCs), is a topic of public concern and scientific interest. This study addresses a specific role of testicular gap junctional intercellular communication (GJIC) between adjacent prepubertal Leydig cells in endocrine disruption and male reproductive toxicity. Organochlorine pesticides (lindane, methoxychlor, DDT), industrial chemicals (PCB153, bisphenol A, nonylphenol and octylphenol) as well as personal care product components (triclosan, triclocarban) rapidly dysregulated GJIC in murine Leydig TM3 cells. The selected GJIC-inhibiting EDCs (methoxychlor, triclosan, triclocarban, lindane, DDT) caused the immediate GJIC disruption by the relocation of gap junctional protein connexin 43 (Cx43) from the plasma membrane and the alternation of Cx43 phosphorylation pattern (Ser368, Ser279, Ser282) of its full-length and two N-truncated isoforms. After more prolonged exposure (24 h), EDCs decreased steady-state levels of full-length Cx43 protein and its two N-truncated isoforms, and eventually (triclosan, triclocarban) also tight junction protein Tjp-1. The disturbance of GJIC was accompanied by altered activity of mitogen-activated protein kinases MAPK-Erk1/2 and MAPK-p38, and a decrease in stimulated progesterone production. Our results indicate that EDCs might disrupt testicular homeostasis and development via disruption of testicular GJIC, a dysregulation of junctional and non-junctional functions of Cx43, activation of MAPKs, and disruption of an early stage of steroidogenesis in prepubertal Leydig cells. These critical disturbances of Leydig cell development and functions during a prepubertal period might be contributing to impaired male reproduction health later on.
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Affiliation(s)
- Affiefa Yawer
- RECETOX, Faculty of Science, Masaryk University, Kamenice 753/5, building A29, 625 00 Brno, Czech Republic
| | - Eliška Sychrová
- RECETOX, Faculty of Science, Masaryk University, Kamenice 753/5, building A29, 625 00 Brno, Czech Republic
| | - Petra Labohá
- RECETOX, Faculty of Science, Masaryk University, Kamenice 753/5, building A29, 625 00 Brno, Czech Republic
| | - Jan Raška
- RECETOX, Faculty of Science, Masaryk University, Kamenice 753/5, building A29, 625 00 Brno, Czech Republic
| | - Tomáš Jambor
- BioFood Centre, Faculty of Biotechnology and Food Sciences, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 949 76 Nitra, Slovac Republic
| | - Pavel Babica
- RECETOX, Faculty of Science, Masaryk University, Kamenice 753/5, building A29, 625 00 Brno, Czech Republic
| | - Iva Sovadinová
- RECETOX, Faculty of Science, Masaryk University, Kamenice 753/5, building A29, 625 00 Brno, Czech Republic.
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Nyffeler J, Chovancova P, Dolde X, Holzer AK, Purvanov V, Kindinger I, Kerins A, Higton D, Silvester S, van Vugt-Lussenburg BMA, Glaab E, van der Burg B, Maclennan R, Legler DF, Leist M. A structure-activity relationship linking non-planar PCBs to functional deficits of neural crest cells: new roles for connexins. Arch Toxicol 2017; 92:1225-1247. [PMID: 29164306 DOI: 10.1007/s00204-017-2125-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Accepted: 11/15/2017] [Indexed: 12/14/2022]
Abstract
Migration of neural crest cells (NCC) is a fundamental developmental process, and test methods to identify interfering toxicants have been developed. By examining cell function endpoints, as in the 'migration-inhibition of NCC (cMINC)' assay, a large number of toxicity mechanisms and protein targets can be covered. However, the key events that lead to the adverse effects of a given chemical or group of related compounds are hard to elucidate. To address this issue, we explored here, whether the establishment of two overlapping structure-activity relationships (SAR)-linking chemical structure on the one hand to a phenotypic test outcome, and on the other hand to a mechanistic endpoint-was useful as strategy to identify relevant toxicity mechanisms. For this purpose, we chose polychlorinated biphenyls (PCB) as a large group of related, but still toxicologically and physicochemically diverse structures. We obtained concentration-dependent data for 26 PCBs in the cMINC assay. Moreover, the test chemicals were evaluated by a new high-content imaging method for their effect on cellular re-distribution of connexin43 and for their capacity to inhibit gap junctions. Non-planar PCBs inhibited NCC migration. The potency (1-10 µM) correlated with the number of ortho-chlorine substituents; non-ortho-chloro (planar) PCBs were non-toxic. The toxicity to NCC partially correlated with gap junction inhibition, while it fully correlated (p < 0.0004) with connexin43 cellular re-distribution. Thus, our double-SAR strategy revealed a mechanistic step tightly linked to NCC toxicity of PCBs. Connexin43 patterns in NCC may be explored as a new endpoint relevant to developmental toxicity screening.
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Affiliation(s)
- Johanna Nyffeler
- In vitro Toxicology and Biomedicine, Department Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Universitaetsstr. 10, 78457, Konstanz, Germany.,Research Training Group RTG1331, 78457, Konstanz, Germany
| | - Petra Chovancova
- In vitro Toxicology and Biomedicine, Department Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Universitaetsstr. 10, 78457, Konstanz, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), 78457, Konstanz, Germany
| | - Xenia Dolde
- In vitro Toxicology and Biomedicine, Department Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Universitaetsstr. 10, 78457, Konstanz, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), 78457, Konstanz, Germany
| | - Anna-Katharina Holzer
- In vitro Toxicology and Biomedicine, Department Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Universitaetsstr. 10, 78457, Konstanz, Germany
| | - Vladimir Purvanov
- Biotechnology Institute Thurgau at the University of Konstanz, 8280, Kreuzlingen, Switzerland
| | - Ilona Kindinger
- Biotechnology Institute Thurgau at the University of Konstanz, 8280, Kreuzlingen, Switzerland
| | - Anna Kerins
- Cyprotex Discovery, No 24 Mereside, Alderley Park, Cheshire, SK10 4TG, UK
| | - David Higton
- Cyprotex Discovery, No 24 Mereside, Alderley Park, Cheshire, SK10 4TG, UK
| | - Steve Silvester
- Cyprotex Discovery, No 24 Mereside, Alderley Park, Cheshire, SK10 4TG, UK
| | | | - Enrico Glaab
- Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, 4362, Esch-sur-Alzette, Luxembourg
| | - Bart van der Burg
- BioDetection Systems bv, Science Park 406, 1098XH, Amsterdam, The Netherlands
| | - Richard Maclennan
- Cyprotex Discovery, No 24 Mereside, Alderley Park, Cheshire, SK10 4TG, UK
| | - Daniel F Legler
- Research Training Group RTG1331, 78457, Konstanz, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), 78457, Konstanz, Germany.,Biotechnology Institute Thurgau at the University of Konstanz, 8280, Kreuzlingen, Switzerland
| | - Marcel Leist
- In vitro Toxicology and Biomedicine, Department Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Universitaetsstr. 10, 78457, Konstanz, Germany. .,Research Training Group RTG1331, 78457, Konstanz, Germany. .,Konstanz Research School Chemical Biology (KoRS-CB), 78457, Konstanz, Germany.
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12
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Totland MZ, Bergsland CH, Fykerud TA, Knudsen LM, Rasmussen NL, Eide PW, Yohannes Z, Sørensen V, Brech A, Lothe RA, Leithe E. E3 ubiquitin ligase NEDD4 induces endocytosis and lysosomal sorting of connexin43 to promote loss of gap junctions. J Cell Sci 2017; 130:2867-2882. [DOI: 10.1242/jcs.202408] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 07/12/2017] [Indexed: 01/07/2023] Open
Abstract
Intercellular communication via gap junctions has an important role in controlling cell growth and in maintaining tissue homeostasis. Connexin43 is the most abundantly expressed gap junction channel protein in humans and acts as a tumor suppressor in multiple tissue types. Connexin43 is often dysregulated at the post-translational level during cancer development, resulting in loss of gap junctions. However, the molecular basis underlying the aberrant regulation of connexin43 in cancer cells has remained elusive. Here, we demonstrate that the oncogenic E3 ubiquitin ligase NEDD4 regulates the connexin43 protein level in HeLa cells, both under basal conditions and in response to protein kinase C activation. Furthermore, overexpression of NEDD4, but not a catalytically inactive form of NEDD4, was found to result in nearly complete loss of gap junctions and increased lysosomal degradation of connexin43 in both HeLa and C33A cervical carcinoma cells. Collectively, the data provide new insights into the molecular basis underlying the regulation of gap junction size and represent the first evidence that an oncogenic E3 ubiquitin ligase promotes loss of gap junctions and connexin43 degradation in human carcinoma cells.
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Affiliation(s)
- Max Z. Totland
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Institute for Biosciences, University of Oslo, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
| | - Christian H. Bergsland
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Institute for Biosciences, University of Oslo, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
| | - Tone A. Fykerud
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
| | - Lars M. Knudsen
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Institute for Biosciences, University of Oslo, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
| | - Nikoline L. Rasmussen
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Institute for Biosciences, University of Oslo, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
| | - Peter W. Eide
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
| | - Zeremariam Yohannes
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
| | - Vigdis Sørensen
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Department of Core Facilities, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Andreas Brech
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Institute for Biosciences, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Department of Core Facilities, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Ragnhild A. Lothe
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Institute for Biosciences, University of Oslo, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
| | - Edward Leithe
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
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13
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Babica P, Zurabian R, Kumar ER, Chopra R, Mianecki MJ, Park JS, Jaša L, Trosko JE, Upham BL. Methoxychlor and Vinclozolin Induce Rapid Changes in Intercellular and Intracellular Signaling in Liver Progenitor Cells. Toxicol Sci 2016; 153:174-85. [PMID: 27413106 DOI: 10.1093/toxsci/kfw114] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Methoxychlor (MXC) and vinclozolin (VIN) are well-recognized endocrine disrupting chemicals known to alter epigenetic regulations and transgenerational inheritance; however, non-endocrine disruption endpoints are also important. Thus, we determined the effects of MXC and VIN on the dysregulation of gap junctional intercellular communication (GJIC) and activation of mitogen-activated protein kinases (MAPKs) in WB-F344 rat liver epithelial cells. Both chemicals induced a rapid dysregulation of GJIC at non-cytotoxic doses, with 30 min EC50 values for GJIC inhibition being 10 µM for MXC and 126 µM for VIN. MXC inhibited GJIC for at least 24 h, while VIN effects were transient and GJIC recovered after 4 h. VIN induced rapid hyperphosphorylation and internalization of gap junction protein connexin43, and both chemicals also activated MAPK ERK1/2 and p38. Effects on GJIC were not prevented by MEK1/2 inhibitor, but by an inhibitor of phosphatidylcholine-specific phospholipase C (PC-PLC), resveratrol, and in the case of VIN, also, by a p38 inhibitor. Estrogen (ER) and androgen receptor (AR) modulators (estradiol, ICI 182,780, HPTE, testosterone, flutamide, VIN M2) did not attenuate MXC or VIN effects on GJIC. Our data also indicate that the effects were elicited by the parental compounds of MXC and VIN. Our study provides new evidence that MXC and VIN dysregulate GJIC via mechanisms involving rapid activation of PC-PLC occurring independently of ER- or AR-dependent genomic signaling. Such alterations of rapid intercellular and intracellular signaling events involved in regulations of gene expression, tissue development, function and homeostasis, could also contribute to transgenerational epigenetic effects of endocrine disruptors.
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Affiliation(s)
- Pavel Babica
- *Department of Experimental Phycology and Ecotoxicology, Institute of Botany, Brno 60200, Czech Republic; RECETOX, Faculty of Science, Masaryk University, Brno 62500, Czech Republic; Department of Pediatrics and Human Development, and Institute for Integrative Toxicology, Michigan State University, East Lansing, Michigan 48824;
| | - Rimma Zurabian
- Department of Pediatrics and Human Development, and Institute for Integrative Toxicology, Michigan State University, East Lansing, Michigan 48824; Department of Microbiology and Parasitology, Faculty of Medicine, National Autonomous University of Mexico, CdMx, 04510, Mexico
| | - Esha R Kumar
- Department of Pediatrics and Human Development, and Institute for Integrative Toxicology, Michigan State University, East Lansing, Michigan 48824
| | - Rajus Chopra
- Department of Pediatrics and Human Development, and Institute for Integrative Toxicology, Michigan State University, East Lansing, Michigan 48824
| | - Maxwell J Mianecki
- Department of Pediatrics and Human Development, and Institute for Integrative Toxicology, Michigan State University, East Lansing, Michigan 48824
| | - Joon-Suk Park
- Department of Pediatrics and Human Development, and Institute for Integrative Toxicology, Michigan State University, East Lansing, Michigan 48824; Laboratory Animal Center, Daegu-Gyeongbuk Medical Innovation Foundation, Daegu, Korea
| | - Libor Jaša
- *Department of Experimental Phycology and Ecotoxicology, Institute of Botany, Brno 60200, Czech Republic; RECETOX, Faculty of Science, Masaryk University, Brno 62500, Czech Republic
| | - James E Trosko
- Department of Pediatrics and Human Development, and Institute for Integrative Toxicology, Michigan State University, East Lansing, Michigan 48824
| | - Brad L Upham
- Department of Pediatrics and Human Development, and Institute for Integrative Toxicology, Michigan State University, East Lansing, Michigan 48824
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14
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Li H, Spagnol G, Zheng L, Stauch KL, Sorgen PL. Regulation of Connexin43 Function and Expression by Tyrosine Kinase 2. J Biol Chem 2016; 291:15867-80. [PMID: 27235399 DOI: 10.1074/jbc.m116.727008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Indexed: 11/06/2022] Open
Abstract
Connexin43 (Cx43) assembly and degradation, the regulation of electrical and metabolic coupling, as well as modulating the interaction with other proteins, involve phosphorylation. Here, we identified and characterized the biological significance of a novel tyrosine kinase that phosphorylates Cx43, tyrosine kinase 2 (Tyk2). Activation of Tyk2 led to a decrease in Cx43 gap junction communication by increasing the turnover rate of Cx43 from the plasma membrane. Tyk2 directly phosphorylated Cx43 residues Tyr-247 and Tyr-265, leading to indirect phosphorylation on residues Ser-279/Ser-282 (MAPK) and Ser-368 (PKC). Although this phosphorylation pattern is similar to what has been observed following Src activation, the response caused by Tyk2 occurred when Src was inactive in NRK cells. Knockdown of Tyk2 at the permissive temperature (active v-Src) in LA-25 cells decreased Cx43 phosphorylation, indicating that although activation of Tyk2 and v-Src leads to phosphorylation of the same Cx43CT residues, they are not identical in level at each site. Additionally, angiotensin II activation of Tyk2 increased the intracellular protein level of Cx43 via STAT3. These findings indicate that, like Src, Tyk2 can also inhibit gap junction communication by phosphorylating Cx43.
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Affiliation(s)
- Hanjun Li
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
| | - Gaelle Spagnol
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
| | - Li Zheng
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
| | - Kelly L Stauch
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
| | - Paul L Sorgen
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
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15
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Leithe E. Regulation of connexins by the ubiquitin system: Implications for intercellular communication and cancer. Biochim Biophys Acta Rev Cancer 2016; 1865:133-46. [DOI: 10.1016/j.bbcan.2016.02.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 01/15/2016] [Accepted: 02/04/2016] [Indexed: 12/31/2022]
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16
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Khan S, Shukla S, Sinha S, Meeran SM. Epigenetic targets in cancer and aging: dietary and therapeutic interventions. Expert Opin Ther Targets 2016; 20:689-703. [PMID: 26667209 DOI: 10.1517/14728222.2016.1132702] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
INTRODUCTION Epigenetic regulation plays a critical role in normal growth and embryonic development by controlling the transcriptional activities of several genes. A growing number of epigenetic changes have been reported in the regulation of key genes involved in cancer and aging. Drugs with epigenetic modulatory activities, mainly histone deacetylase and DNA methyltransferase inhibitors, have received wider attention in aging and cancer research. AREAS COVERED In this review, we summarize the major epigenetic alterations in cancer and aging, with special emphasis on possible therapeutic targets and interventions by dietary as well as bioactive phytochemicals. EXPERT OPINION Some epigenetic-targeting drugs have received FDA approval and many others are undergoing different phases of clinical trials for cancer therapy. In addition to the synthetic compounds, several bioactive phytochemicals and dietary interventions, such as caloric restriction, have been shown to possess epigenetic modulatory activities in multiple cancers. These epigenetic modulators have been shown to delay aging and minimize the risk of cancer both in preclinical as well as clinical models. Therefore, knowledge of bioactive phytochemicals along with dietary interventions can be utilized for cancer prevention and therapy both alone and with existing drugs to achieve optimum efficacy.
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Affiliation(s)
- Sajid Khan
- a Division of Endocrinology , CSIR-Central Drug Research Institute , Lucknow , India
| | - Samriddhi Shukla
- a Division of Endocrinology , CSIR-Central Drug Research Institute , Lucknow , India
| | - Sonam Sinha
- a Division of Endocrinology , CSIR-Central Drug Research Institute , Lucknow , India
| | - Syed Musthapa Meeran
- a Division of Endocrinology , CSIR-Central Drug Research Institute , Lucknow , India
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17
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Nahta R, Al-Mulla F, Al-Temaimi R, Amedei A, Andrade-Vieira R, Bay SN, Brown DG, Calaf GM, Castellino RC, Cohen-Solal KA, Colacci A, Cruickshanks N, Dent P, Di Fiore R, Forte S, Goldberg GS, Hamid RA, Krishnan H, Laird DW, Lasfar A, Marignani PA, Memeo L, Mondello C, Naus CC, Ponce-Cusi R, Raju J, Roy D, Roy R, Ryan EP, Salem HK, Scovassi AI, Singh N, Vaccari M, Vento R, Vondráček J, Wade M, Woodrick J, Bisson WH. Mechanisms of environmental chemicals that enable the cancer hallmark of evasion of growth suppression. Carcinogenesis 2015; 36 Suppl 1:S2-18. [PMID: 26106139 DOI: 10.1093/carcin/bgv028] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
As part of the Halifax Project, this review brings attention to the potential effects of environmental chemicals on important molecular and cellular regulators of the cancer hallmark of evading growth suppression. Specifically, we review the mechanisms by which cancer cells escape the growth-inhibitory signals of p53, retinoblastoma protein, transforming growth factor-beta, gap junctions and contact inhibition. We discuss the effects of selected environmental chemicals on these mechanisms of growth inhibition and cross-reference the effects of these chemicals in other classical cancer hallmarks.
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Affiliation(s)
- Rita Nahta
- Departments of Pharmacology and Hematology & Medical Oncology, Emory University School of Medicine and Winship Cancer Institute, Atlanta, GA 30322, USA, Department of Pathology, Kuwait University, Safat 13110, Kuwait, Department of Experimental and Clinical Medicine, University of Firenze, 50134 Florence, Italy, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada, Program in Genetics and Molecular Biology, Graduate Division of Biological and Biomedical Sciences, Emory University, Atlanta, GA 30322, USA, Department of Environmental and Radiological Health Sciences/Colorado State University/Colorado School of Public Health, Fort Collins, CO 80523-1680, USA, Center for Radiological Research, Columbia University Medical Center, New York, NY 10032, USA, Instituto de Alta Investigacion, Universidad de Tarapaca, Arica 8097877, Chile, Division of Hematology and Oncology, Department of Pediatrics, Children's Healthcare of Atlanta and Emory University, Atlanta, GA 30322, USA, Department of Medicine/Medical Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08901-1914, USA, Center for Environmental Carcinogenesis and Risk Assessment, Environmental Protection and Health Prevention Agency, Bologna 40126, Italy, Departments of Neurosurgery and Biochemistry and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 980033, USA, Department of Biological, Chemical, and Pharmaceutical Sciences and Technologies, Polyclinic Plexus, University of Palermo, 90127 Palermo, Italy, Mediterranean Institute of Oncology, 95029 Viagrande, Italy, Graduate School of Biomedical Sciences and Department of Molecular Biology, School of Osteopathic Medicine, Rowan University, Stratford, NJ 08084-1501, USA, Department of Biomedical Science, Faculty of Medicine and Health Sciences, University Putra, Serdang, Selangor 43400, Malaysia, Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontari
| | - Fahd Al-Mulla
- Department of Pathology, Kuwait University, Safat 13110, Kuwait
| | | | - Amedeo Amedei
- Department of Experimental and Clinical Medicine, University of Firenze, 50134 Florence, Italy
| | - Rafaela Andrade-Vieira
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Sarah N Bay
- Program in Genetics and Molecular Biology, Graduate Division of Biological and Biomedical Sciences, Emory University, Atlanta, GA 30322, USA
| | - Dustin G Brown
- Department of Environmental and Radiological Health Sciences/Colorado State University/Colorado School of Public Health, Fort Collins, CO 80523-1680, USA
| | - Gloria M Calaf
- Center for Radiological Research, Columbia University Medical Center, New York, NY 10032, USA, Instituto de Alta Investigacion, Universidad de Tarapaca, Arica 8097877, Chile
| | - Robert C Castellino
- Division of Hematology and Oncology, Department of Pediatrics, Children's Healthcare of Atlanta and Emory University, Atlanta, GA 30322, USA
| | - Karine A Cohen-Solal
- Department of Medicine/Medical Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08901-1914, USA
| | - Annamaria Colacci
- Center for Environmental Carcinogenesis and Risk Assessment, Environmental Protection and Health Prevention Agency, Bologna 40126, Italy
| | - Nichola Cruickshanks
- Departments of Neurosurgery and Biochemistry and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 980033, USA
| | - Paul Dent
- Departments of Neurosurgery and Biochemistry and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 980033, USA
| | - Riccardo Di Fiore
- Department of Biological, Chemical, and Pharmaceutical Sciences and Technologies, Polyclinic Plexus, University of Palermo, 90127 Palermo, Italy
| | - Stefano Forte
- Mediterranean Institute of Oncology, 95029 Viagrande, Italy
| | - Gary S Goldberg
- Graduate School of Biomedical Sciences and Department of Molecular Biology, School of Osteopathic Medicine, Rowan University, Stratford, NJ 08084-1501, USA
| | - Roslida A Hamid
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, University Putra, Serdang, Selangor 43400, Malaysia
| | - Harini Krishnan
- Graduate School of Biomedical Sciences and Department of Molecular Biology, School of Osteopathic Medicine, Rowan University, Stratford, NJ 08084-1501, USA
| | - Dale W Laird
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Ahmed Lasfar
- Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers, the State University of New Jersey, Piscataway, NJ 60503, USA
| | - Paola A Marignani
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Lorenzo Memeo
- Mediterranean Institute of Oncology, 95029 Viagrande, Italy
| | - Chiara Mondello
- Institute of Molecular Genetics, National Research Council, 27100 Pavia, Italy
| | - Christian C Naus
- Department of Cellular & Physiological Sciences, Life Sciences Institute, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Richard Ponce-Cusi
- Instituto de Alta Investigacion, Universidad de Tarapaca, Arica 8097877, Chile
| | - Jayadev Raju
- Toxicology Research Division, Bureau of Chemical Safety Food Directorate, Health Products and Food Branch Health Canada, Ottawa, Ontario K1A0K9, Canada
| | - Debasish Roy
- Department of Natural Science, The City University of New York at Hostos Campus, Bronx, NY 10451, USA
| | - Rabindra Roy
- Molecular Oncology Program, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington DC 20057, USA
| | - Elizabeth P Ryan
- Department of Environmental and Radiological Health Sciences/Colorado State University/Colorado School of Public Health, Fort Collins, CO 80523-1680, USA
| | - Hosni K Salem
- Urology Dept., kasr Al-Ainy School of Medicine, Cairo University, El Manial, Cairo 12515, Egypt
| | - A Ivana Scovassi
- Institute of Molecular Genetics, National Research Council, 27100 Pavia, Italy
| | - Neetu Singh
- Advanced Molecular Science Research Centre, King George's Medical University, Lucknow, UP 226003, India
| | - Monica Vaccari
- Center for Environmental Carcinogenesis and Risk Assessment, Environmental Protection and Health Prevention Agency, Bologna 40126, Italy
| | - Renza Vento
- Department of Biological, Chemical, and Pharmaceutical Sciences and Technologies, Polyclinic Plexus, University of Palermo, 90127 Palermo, Italy, Sbarro Institute for Cancer Research and Molecular Medicine, College of Science and Technology, Temple University, Philadelphia, PA 19122, USA
| | - Jan Vondráček
- Department of Cytokinetics, Institute of Biophysics AS CR, Brno 612 65, Czech Republic
| | - Mark Wade
- Center for Genomic Science of IIT@SEMM, Istituto Italiano di Tecnologia (IIT), Milan 16163, Italy and
| | - Jordan Woodrick
- Molecular Oncology Program, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington DC 20057, USA
| | - William H Bisson
- Environmental and Molecular Toxicology, Environmental Health Sciences Center, Oregon State University, Corvallis, OR 97331, USA
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18
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Zou H, Liu X, Han T, Hu D, Wang Y, Yuan Y, Gu J, Bian J, Zhu J, Liu ZP. Salidroside Protects against Cadmium-Induced Hepatotoxicity in Rats via GJIC and MAPK Pathways. PLoS One 2015; 10:e0129788. [PMID: 26070151 PMCID: PMC4466396 DOI: 10.1371/journal.pone.0129788] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 05/13/2015] [Indexed: 12/29/2022] Open
Abstract
It is known that cadmium (Cd) induces cytotoxicity in hepatocytes; however, the underlying mechanism is unclear. Here, we studied the molecular mechanisms of Cd-induced hepatotoxicity in rat liver cells (BRL 3A) and in vivo. We observed that Cd treatment was associated with a time- and concentration-dependent decrease in the cell index (CI) of BRL 3A cells and cellular organelle ultrastructure injury in the rat liver. Meanwhile, Cd treatment resulted in the inhibition of gap junction intercellular communication (GJIC) and activation of mitogen-activated protein kinase (MAPK) pathways. Gap junction blocker 18-β-glycyrrhetinic acid (GA), administered in combination with Cd, exacerbated cytotoxic injury in BRL 3A cells; however, GA had a protective effect on healthy cells co-cultured with Cd-exposed cells in a co-culture system. Cd-induced cytotoxic injury could be attenuated by co-treatment with an extracellular signal-regulated kinase (ERK) inhibitor (U0126) and a p38 inhibitor (SB202190) but was not affected by co-treatment with a c-Jun N-terminal kinase (JNK) inhibitor (SP600125). These results indicate that ERK and p38 play critical roles in Cd-induced hepatotoxicity and mediate the function of gap junctions. Moreover, MAPKs induce changes in GJIC by controlling connexin gene expression, while GJIC has little effect on the Cd-induced activation of MAPK pathways. Collectively, our study has identified a possible mechanistic pathway of Cd-induced hepatotoxicity in vitro and in vivo, and identified the participation of GJIC and MAPK-mediated pathways in Cd-induced hepatotoxicity. Furthermore, we have shown that salidroside may be a functional chemopreventative agent that ameliorates the negative effects of Cd via GJIC and MAPK pathways.
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Affiliation(s)
- Hui Zou
- College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, P.R. China
| | - Xuezhong Liu
- College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, P.R. China
| | - Tao Han
- College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, P.R. China
| | - Di Hu
- College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, P.R. China
| | - Yi Wang
- College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, P.R. China
| | - Yan Yuan
- College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, P.R. China
| | - Jianhong Gu
- College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, P.R. China
| | - Jianchun Bian
- College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, P.R. China
| | - Jiaqiao Zhu
- College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, P.R. China
| | - Zong-ping Liu
- College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, P.R. China
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19
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De Mello WC. Chemical communication between cardiac cells is disrupted by high glucose: Implications for the diabetic heart. Exp Cell Res 2015; 331:232-238. [DOI: 10.1016/j.yexcr.2014.09.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 09/12/2014] [Accepted: 09/15/2014] [Indexed: 01/24/2023]
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20
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Li H, Spagnol G, Naslavsky N, Caplan S, Sorgen PL. TC-PTP directly interacts with connexin43 to regulate gap junction intercellular communication. J Cell Sci 2014; 127:3269-79. [PMID: 24849651 DOI: 10.1242/jcs.145193] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Protein kinases have long been reported to regulate connexins; however, little is known about the involvement of phosphatases in the modulation of intercellular communication through gap junctions and the subsequent downstream effects on cellular processes. Here, we identify an interaction between the T-cell protein tyrosine phosphatase (TC-PTP, officially known as PTPN2) and the carboxyl terminus of connexin43 (Cx43, officially known as GJA1). Two cell lines, normal rat kidney (NRK) cells endogenously expressing Cx43 and an NRK-derived cell line expressing v-Src with temperature-sensitive activity, were used to demonstrate that EGF and v-Src stimulation, respectively, induced TC-PTP to colocalize with Cx43 at the plasma membrane. Cell biology experiments using phospho-specific antibodies and biophysical assays demonstrated that the interaction is direct and that TC-PTP dephosphorylates Cx43 residues Y247 and Y265, but does not affect v-Src. Transfection of TC-PTP also indirectly led to the dephosphorylation of Cx43 S368, by inactivating PKCα and PKCδ, with no effect on the phosphorylation of S279 and S282 (MAPK-dependent phosphorylation sites). Dephosphorylation maintained Cx43 gap junctions at the plaque and partially reversed the channel closure caused by v-Src-mediated phosphorylation of Cx43. Understanding dephosphorylation, along with the well-documented roles of Cx43 phosphorylation, might eventually lead to methods to modulate the regulation of gap junction channels, with potential benefits for human health.
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Affiliation(s)
- Hanjun Li
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Gaelle Spagnol
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Naava Naslavsky
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Steve Caplan
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Paul L Sorgen
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
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21
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Stern AH. Hazard identification of the potential for dieldrin carcinogenicity to humans. ENVIRONMENTAL RESEARCH 2014; 131:188-214. [PMID: 24727642 DOI: 10.1016/j.envres.2014.02.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 01/08/2014] [Accepted: 02/20/2014] [Indexed: 06/03/2023]
Abstract
Although dieldrin׳s use in the U.S. was partially banned in the 1970s and its use was completely eliminated in 1987, dieldrin continues to be a common contaminant at hazardous waste sites. The USEPA׳s current cancer potency estimate for dieldrin was derived in 1987 and is based on the production of mouse liver tumors. Because of its environmental persistence and its relatively high USEPA cancer potency estimate, dieldrin functions as a cleanup "driver" in many hazardous site remediations. Since 1987, new risk assessment perspectives and new data on dieldrin׳s carcinogenic potential have arisen. This review presents a reassessment of dielrin׳s human cancer potential in light of these new data and new perspectives. Based on this reassessment, dieldrin may be carcinogenic through multiple modes of action. These modes of action may operate within the same tissue, or may be specific to individual tissues. Of the several possible carcinogenic modes of action for dieldrin, one or more may be more relevant to human cancer risk than others, but the relative importance of each is unknown. In addition, neither the details of the possible modes of action, nor the shape of the tumor dose-response curves associated with each are sufficiently well known to permit quantitative cancer dose-response modeling. Thus, the mouse liver tumor data used by the USEPA in its 1987 assessment remain the only quantitative data available for cancer dose-response modeling.
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Affiliation(s)
- Alan H Stern
- New Jersey Department of Environmental Protection - NJDEP, Office of Science, P.O. Box 420, MC 428-01, Trenton, NJ 08626, United States.
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22
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Lee BK, Chung MY, Lee KW. Benzo[a]pyrene-7,8-diol-9,10-epoxide inhibits gap junction intercellular communication via phosphorylation of tumor progression locus 2 in WB-F344 rat liver epithelial cells. Mol Carcinog 2013; 54:351-8. [PMID: 24249418 DOI: 10.1002/mc.22103] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 10/10/2013] [Accepted: 10/16/2013] [Indexed: 11/12/2022]
Abstract
Benzo[a]pyrene-7,8-diol-9,10-epoxide (B[a]PDE), a major metabolite of benzo[a]pyrene, has been reported to function as a human carcinogen. However, the molecular mechanism of how B[a]PDE regulates signaling pathways during tumor promotion remains unclear. In this study, we investigated the effects of B[a]PDE on the regulation of gap junction intercellular communication (GJIC), one of the major carcinogenic processes, and its main regulatory signaling pathways using WB-F344 rat liver epithelial (WB-F344 RLE) cells. Treatment of benzo[a]pyrene or B[a]PDE resulted in GJIC inhibition, and B[a]PDE was more active at lower concentrations than benzo[a]pyrene in the suppression of GJIC. This suggests that B[a]PDE is a stronger GJIC inhibitor. B[a]PDE at 1 µM reversibly inhibited GJIC in WB-F344 RLE cells, which was attributable to hyperphosphorylation of connexin43 (Cx43) via phosphorylation of mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK) and extracellular signal-regulated kinase (ERK). We found that B[a]PDE induced phosphorylation of tumor progression locus 2 (Tpl2), a direct upstream regulator of MEK. Tpl2 inhibitor recovered B[a]PDE-induced GJIC inhibition and attenuated B[a]PDE-induced MEK/ERK phosphorylation in WB-F344 RLE cells. Collectively, our results suggest that B[a]PDE suppresses GJIC by activating Tpl2 and subsequently the MEK/ERK pathway and Cx43 phosphorylation in WB-F344 RLE cells. These results outline the potential importance of Tpl2 as a novel therapeutic target for B[a]PDE-induced GJIC inhibition during cancer promotion.
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Affiliation(s)
- Bo Kyung Lee
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, 143-701, Republic of Korea; Advanced Institutes of Convergence Technology, Seoul National University, Suwon, 443-270, Republic of Korea
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23
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Martinelli V, Cellot G, Toma FM, Long CS, Caldwell JH, Zentilin L, Giacca M, Turco A, Prato M, Ballerini L, Mestroni L. Carbon nanotubes instruct physiological growth and functionally mature syncytia: nongenetic engineering of cardiac myocytes. ACS NANO 2013; 7:5746-56. [PMID: 23734857 DOI: 10.1021/nn4002193] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Myocardial tissue engineering currently represents one of the most realistic strategies for cardiac repair. We have recently discovered the ability of carbon nanotube scaffolds to promote cell division and maturation in cardiomyocytes. Here, we test the hypothesis that carbon nanotube scaffolds promote cardiomyocyte growth and maturation by altering the gene expression program, implementing the cell electrophysiological properties and improving networking and maturation of functional syncytia. In our study, we combine microscopy, biological and electrophysiological methodologies, and calcium imaging, to verify whether neonatal rat ventricular myocytes cultured on substrates of multiwall carbon nanotubes acquire a physiologically more mature phenotype compared to control (gelatin). We show that the carbon nanotube substrate stimulates the induction of a gene expression profile characteristic of terminal differentiation and physiological growth, with a 2-fold increase of α-myosin heavy chain (P < 0.001) and upregulation of sarcoplasmic reticulum Ca(2+) ATPase 2a. In contrast, markers of pathological hypertrophy remain unchanged (β-myosin heavy chain, skeletal α-actin, atrial natriuretic peptide). These modifications are paralleled by an increase of connexin-43 gene expression, gap junctions and functional syncytia. Moreover, carbon nanotubes appear to exert a protective effect against the pathologic stimulus of phenylephrine. Finally, cardiomyocytes on carbon nanotubes demonstrate a more mature electrophysiological phenotype of syncytia and intracellular calcium signaling. Thus, carbon nanotubes interacting with cardiomyocytes have the ability to promote physiological growth and functional maturation. These properties are unique in the current vexing field of tissue engineering, and offer unprecedented perspectives in the development of innovative therapies for cardiac repair.
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24
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Hix LM, Lockwood SF, Bertram JS. Bioactive carotenoids: potent antioxidants and regulators of gene expression. Redox Rep 2013; 9:181-91. [PMID: 15479561 DOI: 10.1179/135100004225005967] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Carotenoids are plant pigments, some of which act as a vital source of vitamin A to all animals, that appear to have additional benefits to primates. They are potent antioxidants and photoprotectants and can additionally modulate gene activity resulting in protection from experimentally-induced inflammatory damage and neoplastic transformation. Anti-neoplastic properties appear tightly correlated to their ability to induce the gap junctional protein connexin 43 (Cx43). This when upregulated leads to decreased proliferation and decreased indices of neoplasia in animal and human cells. Delivery of natural carotenoids can be compromised by poor bioavailability. To overcome this, a synthetic water-dispersible derivative of astaxanthin has been synthesized and shown to be: highly bioavailable; a potent antioxidant; protective against experimental ischemia-reperfusion injury and capable of inducing Cx43, suggesting antineoplastic potential. The ability to deliver biologically active carotenoids at high concentration and with good reproducibility appears to have been achieved.
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Affiliation(s)
- Laura M Hix
- Department of Cell and Molecular Biology and Cancer Research Center of Hawaii, University of Hawaii at Manoa, 1236 Laulala Street, Honolulu, HI 96813, USA
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25
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Andrysík Z, Procházková J, Kabátková M, Umannová L, Šimečková P, Kohoutek J, Kozubík A, Machala M, Vondráček J. Aryl hydrocarbon receptor-mediated disruption of contact inhibition is associated with connexin43 downregulation and inhibition of gap junctional intercellular communication. Arch Toxicol 2012; 87:491-503. [DOI: 10.1007/s00204-012-0963-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Accepted: 10/11/2012] [Indexed: 11/29/2022]
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26
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Matesic DF, Sidorova TS, Burns TJ, Bell AM, Tran PL, Ruch RJ, May SW. p38 MAPK activation, JNK inhibition, neoplastic growth inhibition, and increased gap junction communication in human lung carcinoma and Ras-transformed cells by 4-phenyl-3-butenoic acid. J Cell Biochem 2012; 113:269-81. [PMID: 21898549 DOI: 10.1002/jcb.23353] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Human lung neoplasms frequently express mutations that down-regulate expression of various tumor suppressor molecules, including mitogen-activated protein kinases such as p38 MAPK. Conversely, activation of p38 MAPK in tumor cells results in cancer cell cycle inhibition or apoptosis initiated by chemotherapeutic agents such as retinoids or cisplatin, and is therefore an attractive approach for experimental anti-tumor therapies. We now report that 4-phenyl-3-butenoic acid (PBA), an experimental compound that reverses the transformed phenotype at non-cytotoxic concentrations, activates p38 MAPK in tumorigenic cells at concentrations and treatment times that correlate with decreased cell growth and increased cell-cell communication. H2009 human lung carcinoma cells and ras-transformed rat liver epithelial cells treated with PBA showed increased activation of p38 MAPK and its downstream effectors which occurred after 4 h and lasted beyond 48 h. Untransformed plasmid control cells showed low activation of p38 MAPK compared to ras-transformed and H2009 carcinoma cells, which correlates with the reduced effect of PBA on untransformed cell growth. The p38 MAPK inhibitor, SB203580, negated PBA's activation of p38 MAPK downstream effectors. PBA also increased cell-cell communication and connexin 43 phosphorylation in ras-transformed cells, which were prevented by SB203580. In addition, PBA decreased activation of JNK, which is upregulated in many cancers. Taken together, these results suggest that PBA exerts its growth regulatory effect in tumorigenic cells by concomitant up-regulation of p38 MAPK activity, altered connexin 43 expression, and down-regulation of JNK activity. PBA may therefore be an effective therapeutic agent in human cancers that exhibit down-regulated p38 MAPK activity and/or activated JNK and altered cell-cell communication.
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Affiliation(s)
- Diane F Matesic
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Mercer University, Atlanta, Georgia 30341, USA.
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27
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Trosko JE. Pre-Natal Epigenetic Influences on Acute and Chronic Diseases Later in Life, such as Cancer: Global Health Crises Resulting from a Collision of Biological and Cultural Evolution. Prev Nutr Food Sci 2011. [DOI: 10.3746/jfn.2011.16.4.394] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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28
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Yang Y, Cao MH, Wang Q, Yuan DD, Li L, Tao L. The effects of 2-aminoethoxydiphenyl borate and diphenylboronic anhydride on gap junctions composed of Connexin43 in TM₄ sertoli cells. Biol Pharm Bull 2011; 34:1390-7. [PMID: 21881223 DOI: 10.1248/bpb.34.1390] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
2-Aminoethoxydiphenyl borate (2-APB) has recently been demonstrated to inhibit gap junction (GJ) channels, whereas the underlying mechanisms are still unknown. Using mouse TM₄ Sertoli cell which expresses connexin43 (Cx43), we explored the effects of 2-APB and its analogues on dye-coupling through junctional channels formed by Cx43 and on expression of Cx43. Exposure of the cells to 2-APB (1-50 µM) and one of its analogues diphenylboronic anhydride (DPBA) (1-30 µM) for 4 h leads to a significant decrease in dye coupling of GJ in a concentration-dependent manner. The inhibitory effects of 2-APB and DPBA are reversible since decreased GJ coupling resumes after the two compounds are washed out. The disfunction of GJ induced by 2-APB and DPBA is associated with a decrease in total amount of Cx43 protein and number of GJs on the cell membrane. 2-APB and DPBA do not alter Cx43 phosphorylation state and the level of Cx43 mRNA expression. The loss of Cx43 protein is prevented by either lysosomal or proteasomal inhibitor, suggesting that the decrease in Cx43 results from a 2-APB or DPBA-enhanced degradation of Cx43. The present results indicate that 2-APB and DPBA inhibit GJ communication through decreasing Cx43 expression in TM₄ cells.
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Affiliation(s)
- Yan Yang
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, China
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29
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Leithe E, Sirnes S, Fykerud T, Kjenseth A, Rivedal E. Endocytosis and post-endocytic sorting of connexins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1870-9. [PMID: 21996040 DOI: 10.1016/j.bbamem.2011.09.029] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 09/19/2011] [Accepted: 09/28/2011] [Indexed: 12/15/2022]
Abstract
The connexins constitute a family of integral membrane proteins that form intercellular channels, enabling adjacent cells in solid tissues to directly exchange ions and small molecules. These channels assemble into distinct plasma membrane domains known as gap junctions. Gap junction intercellular communication plays critical roles in numerous cellular processes, including control of cell growth and differentiation, maintenance of tissue homeostasis and embryonic development. Gap junctions are dynamic plasma membrane domains, and there is increasing evidence that modulation of endocytosis and post-endocytic trafficking of connexins are important mechanisms for regulating the level of functional gap junctions at the plasma membrane. The emerging picture is that multiple pathways exist for endocytosis and sorting of connexins to lysosomes, and that these pathways are differentially regulated in response to physiological and pathophysiological stimuli. Recent studies suggest that endocytosis and lysosomal degradation of connexins is controlled by a complex interplay between phosphorylation and ubiquitination. This review summarizes recent progress in understanding the molecular mechanisms involved in endocytosis and post-endocytic sorting of connexins, and the relevance of these processes to the regulation of gap junction intercellular communication under normal and pathophysiological conditions. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.
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Affiliation(s)
- Edward Leithe
- Department of Cancer Prevention, Oslo University Hospital, Oslo, Norway
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30
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Banerjee D, Das S, Molina SA, Madgwick D, Katz MR, Jena S, Bossmann LK, Pal D, Takemoto DJ. Investigation of the reciprocal relationship between the expression of two gap junction connexin proteins, connexin46 and connexin43. J Biol Chem 2011; 286:24519-33. [PMID: 21606502 DOI: 10.1074/jbc.m110.217208] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Connexins are the transmembrane proteins that form gap junctions between adjacent cells. The function of the diverse connexin molecules is related to their tissue-specific expression and highly dynamic turnover. Although multiple connexins have been previously reported to compensate for each other's functions, little is known about how connexins influence their own expression or intracellular regulation. Of the three vertebrate lens connexins, two connexins, connexin43 (Cx43) and connexin46 (Cx46), show reciprocal expression and subsequent function in the lens and in lens cell culture. In this study, we investigate the reciprocal relationship between the expression of Cx43 and Cx46. Forced depletion of Cx43, by tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate, is associated with an up-regulation of Cx46 at both the protein and message level in human lens epithelial cells. An siRNA-mediated down-regulation of Cx43 results in an increase in the level of Cx46 protein, suggesting endogenous Cx43 is involved in the regulation of endogenous Cx46 turnover. Overexpression of Cx46, in turn, induces the depletion of Cx43 in rabbit lens epithelial cells. Cx46-induced Cx43 degradation is likely mediated by the ubiquitin-proteasome pathway, as (i) treatment with proteasome inhibitors restores the Cx43 protein level and (ii) there is an increase in Cx43 ubiquitin conjugation in Cx46-overexpressing cells. We also present data that shows that the C-terminal intracellular tail domain of Cx46 is essential to induce degradation of Cx43. Therefore, our study shows that Cx43 and Cx46 have novel functions in regulating each other's expression and turnover in a reciprocal manner in addition to their conventional roles as gap junction proteins in lens cells.
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Affiliation(s)
- Debarshi Banerjee
- Department of Biochemistry, Kansas State University, Manhattan, Kansas 66506, USA
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31
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Spray DC, Suadicani SO, Srinivas M, Gutstein DE, Fishman GI. Gap Junctions in the Cardiovascular System. Compr Physiol 2011. [DOI: 10.1002/cphy.cp020104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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32
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Kang HG, Jeong SH, Cho JH. Antimutagenic and anticarcinogenic effect of methanol extracts of Petasites japonicus Maxim leaves. J Vet Sci 2010; 11:51-8. [PMID: 20195065 PMCID: PMC2833430 DOI: 10.4142/jvs.2010.11.1.51] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The methanol extract from the leaves of Petasites japonicus Maxim (PJ) was studied for its (anti-)mutagenic effect with the SOS chromotest and reverse mutation assay. The (anti-)carcinogenic effects were evaluated by the cytotoxicity on human cancer line cells and by the function and the expression of gap junctions in rat liver epithelial cell. PJ extracts significantly decreased spontaneous β-galactosidase activity and β-galactosidase activity induced by a mutagen, ICR, in Salmonella (S.) typhimurium TA 1535/pSK 1002. All doses of the extract (0.08-100 mg/plate) decreased the reversion frequency induced by benzo (α)pyrene (BaP) in S. typhimurium TA 98. It decreased not only the spontaneous reversion frequency but also that induced by BaP in S. typhimurium TA 100. PJ extract showed greater cytotoxic effects on human stomach, colon and uterus cancer cells than on other cancer cell types and normal rat liver epithelial cells. Dye transfers though gap junctions were significantly increased by PJ extracts at concentrations greater than 200 µg/mL and the inhibition of dye transfer by 12-O-tetradecanoylphorobol-13-acetate (TPA) was obstructed in all concentrations of PJ. PJ significantly increased the numbers of gap junction protein connexin 43, and increased the protein expression decreased by TPA in a dose-dependent manner. Based on these findings, PJ is suggested to contain antimutagenic and anticarcionogenic compounds.
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Affiliation(s)
- Hwan-Goo Kang
- National Veterinary Research and Quarantine Service, Anyang, Korea
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33
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Lee CH, Chen IH, Lee CR, Chi CH, Tsai MC, Tsai JL, Lin HF. Inhibition of gap junctional Intercellular communication in WB-F344 rat liver epithelial cells by triphenyltin chloride through MAPK and PI3-kinase pathways. J Occup Med Toxicol 2010; 5:17. [PMID: 20591183 PMCID: PMC2904784 DOI: 10.1186/1745-6673-5-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Accepted: 06/30/2010] [Indexed: 11/10/2022] Open
Abstract
Background Organotin compounds (OTCs) have been widely used as stabilizers in the production of plastic, agricultural pesticides, antifoulant plaints and wood preservation. The toxicity of triphenyltin (TPT) compounds was known for their embryotoxic, neurotoxic, genotoxic and immunotoxic effects in mammals. The carcinogenicity of TPT was not well understood and few studies had discussed the effects of OTCs on gap junctional intercellular communication (GJIC) of cells. Method In the present study, the effects of triphenyltin chloride (TPTC) on GJIC in WB-F344 rat liver epithelial cells were evaluated, using the scrape-loading dye transfer technique. Results TPTC inhibited GJIC after a 30-min exposure in a concentration- and time-dependent manner. Pre-incubation of cells with the protein kinase C (PKC) inhibitor did not modify the response, but the specific MEK 1 inhibitor PD98059 and PI3K inhibitor LY294002 decreased substantially the inhibition of GJIC by TPTC. After WB-F344 cells were exposed to TPTC, phosphorylation of Cx43 increased as seen in Western blot analysis. Conclusions These results show that TPTC inhibits GJIC in WB-F344 rat liver epithelial cells by altering the Cx43 protein expression through both MAPK and PI3-kinase pathways.
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Affiliation(s)
- Chung-Hsun Lee
- Graduate Institute of Occupational Safety and Health, College of Health Science, Kaohsiung Medical University, Kaohsiung 80708, Taiwan.
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Langlois S, Cowan KN, Shao Q, Cowan BJ, Laird DW. The tumor-suppressive function of Connexin43 in keratinocytes is mediated in part via interaction with caveolin-1. Cancer Res 2010; 70:4222-32. [PMID: 20406988 DOI: 10.1158/0008-5472.can-09-3281] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Connexin43 (Cx43) is known to have tumor-suppressive effects, but the underlying mechanisms are still poorly understood. In keratinocytes, we previously showed that the COOH-terminal domain of Cx43 directly interacts with the tumor suppressor Cav-1. We now show that rat epidermal keratinocytes (REK) that are reduced in Cx43 present features of epithelial-to-mesenchymal transition and are more invasive than their control counterparts, whereas overexpression of Cx43 inhibited the 12-O-tetradecanoyl-phorbol-13-acetate (TPA)- and epidermal growth factor (EGF)-induced invasive properties. Carbenoxolone did not alter the inhibitory effect of Cx43 against TPA- and EGF-induced cell invasion, indicating the involvement of a gap junctional intercellular communication-independent mechanism. Interestingly, the association of Cx43 with Cav-1 was found to be reduced after TPA and EGF treatment. Accordingly, the colocalization of Cx43 with Cav-1 was diminished in cells from a human epidermal squamous cell carcinoma, as well as in sections from human keratinocyte tumors, suggesting that Cx43/Cav-1 interaction plays a protective role against keratinocyte transformation. As opposed to cells that overexpress Cx43-GFP, invasion could be induced in rat epidermal keratinocytes that overexpressed a GFP-tagged truncated mutant of Cx43 (Delta244-GFP) that we previously showed not to interact with Cav-1, as well as in cells that overexpressed Cx43-GFP but were reduced in Cav-1. Our data show that Cx43 possesses tumor-suppressive properties in keratinocytes and provide the first evidence that the Cx43/Cav-1 interaction is altered in keratinocyte transformation processes, as well as in human keratinocyte tumors, and that this association might play a role in Cx43-mediated tumor suppression.
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Affiliation(s)
- Stéphanie Langlois
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada
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35
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Kang HG, Jeong SH, Cho JH. Antimutagenic and Anticarcinogenic Effect of Methanol Extracts of Sweetpotato (Ipomea batata) Leaves. Toxicol Res 2010; 26:29-35. [PMID: 24278503 PMCID: PMC3834463 DOI: 10.5487/tr.2010.26.1.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 02/22/2010] [Accepted: 02/25/2010] [Indexed: 11/20/2022] Open
Abstract
The present study was conducted to investigate the antimutagenic potential of the methanolic extract from the leaves of sweet potato (Ipomea batatas, IB) with the SOS chromotest (umu test) and Salmonella typhimurium TA 98 and TA 100. The anticarcinogenic effects were also studied by calculation of the IC50 on human cancer cell lines and investigating the function of gap junction in rat liver epithelial cells. The IB extract inhibited dose-dependently the β-galactosidase activity induced spontaneously at concentration of more than 200 mg/ml in S. typhimurium TA 1535/pSK 1002, and decreased significantly (p < 0.01) the β-galactosidase activities induced by mutagen 6-chloro-9-[3- (2-chloroethylamino) proylamino]-2-methoxyacridine dihydrochloride (ICR) at dose of more than 0.4 mg/0.1 ml. The IB extract showed no effect on the spontaneous reversions of S. typhimurium TA 98 and 100 but benzo (α) pyrene (BaP) -stimulated reversions were decreased dose-dependently (p < 0.01) at the concentration of more than 100 mg/ml. The IC50 value of stomach cancer cells was lower than that of normal rat liver epithelial cells, but the values of colon and uterine cancer cell lines were similar to those of normal rat liver epithelial cells. The transfer of dye through gap junctions was not affected by treatment of the IB extracts at any concentration during treatment periods. The simultaneously treatment of IB extract and 12-O-tetradecanoylphorbol-13-acetate (TPA) effectively prevented the inhibition of dye transfer induced by TPA 1 hour after treatment at all exposed concentrations. The number of gap junctions was significantly (p < 0.01) increased by the treatment with IB extract at concentrations of more than 40 μg/ml. The inhibition of the expression of gap junction proteins by TPA (0.01 μg/ml) was recovered dose dependently by the simultaneous treatment of IB extracts. Our data suggest that Ipomea batatas has antimutagenic and anticarcionogenic activity in vitro.
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Affiliation(s)
- Hwan-Goo Kang
- National Research and Quarantine Service, Anyang 430-757
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Ale-Agha N, Galban S, Sobieroy C, Abdelmohsen K, Gorospe M, Sies H, Klotz LO. HuR regulates gap junctional intercellular communication by controlling beta-catenin levels and adherens junction integrity. Hepatology 2009; 50:1567-76. [PMID: 19676129 PMCID: PMC2784158 DOI: 10.1002/hep.23146] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
UNLABELLED Gap junctional intercellular communication (GJIC) plays a critical role in the regulation of tissue homeostasis and carcinogenesis and is modulated by the levels, subcellular localization, and posttranslational modification of gap junction proteins, the connexins (Cx). Here, using oval cell-like rat liver epithelial cells, we demonstrate that the RNA-binding protein HuR promotes GJIC through two mechanisms. First, HuR silencing lowered the levels of Cx43 protein and Cx43 messenger RNA (mRNA), and decreased Cx43 mRNA half-life. This regulation was likely due to the direct stabilization of Cx43 mRNA by HuR, because HuR associated directly with Cx43 mRNA, a transcript that bears signature adenylate-uridylate-rich (AU-rich) and uridylate-rich (U-rich) sequences in its 3'-untranslated region. Second, HuR silencing reduced both half-life and the levels of beta-catenin mRNA, also a target of HuR; accordingly, HuR silencing lowered the levels of whole-cell and membrane-associated beta-catenin. Coimmunoprecipitation experiments showed a direct interaction between beta-catenin and Cx43. Small interfering RNA (siRNA)-mediated depletion of beta-catenin recapitulated the effects of decreasing HuR levels: it attenuated GJIC, decreased Cx43 levels, and redistributed Cx43 to the cytoplasm, suggesting that depletion of beta-catenin in HuR-silenced cells contributed to lowering Cx43 levels at the membrane. Finally, HuR was demonstrated to support GJIC after exposure to a genotoxic agent, doxorubicin, or an inducer of differentiation processes, retinoic acid, thus pointing to a crucial role of HuR in the cellular response to stress and in physiological processes modulated by GJIC. CONCLUSION HuR promotes gap junctional intercellular communication in rat liver epithelial cells through two related regulatory processes, by enhancing the expression of Cx43 and by increasing the expression of beta-catenin, which, in turn, interacts with Cx43 and is required for proper positioning of Cx43 at the plasma membrane.
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Affiliation(s)
- Niloofar Ale-Agha
- Institut für umweltmedizinische Forschung (IUF) an der Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Stefanie Galban
- Institut für Biochemie und Molekularbiologie I, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany, Laboratory of Cellular and Molecular Biology, National Institute on Aging – Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Christiane Sobieroy
- Institut für Biochemie und Molekularbiologie I, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Kotb Abdelmohsen
- Laboratory of Cellular and Molecular Biology, National Institute on Aging – Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Myriam Gorospe
- Laboratory of Cellular and Molecular Biology, National Institute on Aging – Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Helmut Sies
- Institut für umweltmedizinische Forschung (IUF) an der Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany, Institut für Biochemie und Molekularbiologie I, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Lars-Oliver Klotz
- Institut für umweltmedizinische Forschung (IUF) an der Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany, Institut für Biochemie und Molekularbiologie I, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany,Correspondence should be addressed to
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37
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Neergheen VS, Bahorun T, Taylor EW, Jen LS, Aruoma OI. Targeting specific cell signaling transduction pathways by dietary and medicinal phytochemicals in cancer chemoprevention. Toxicology 2009; 278:229-41. [PMID: 19850100 DOI: 10.1016/j.tox.2009.10.010] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2009] [Revised: 10/06/2009] [Accepted: 10/09/2009] [Indexed: 02/08/2023]
Abstract
Natural phytochemicals derived from dietary sources or medicinal plants have gained significant recognition in the potential management of several human clinical conditions. Much research has also been geared towards the evaluation of plant extracts as effective prophylactic agents since they can act on specific and/or multiple molecular and cellular targets. Plants have been an abundant source of highly effective phytochemicals which offer great potential in the fight against cancer by inhibiting the process of carcinogenesis through the upregulation of cytoprotective genes that encode for carcinogen detoxifying enzymes and antioxidant enzymes. The mechanistic insight into chemoprevention further includes induction of cell cycle arrest and apoptosis or inhibition of signal transduction pathways mainly the mitogen-activated protein kinases (MAPK), protein kinases C (PKC), phosphoinositide 3-kinase (PI3K), glycogen synthase kinase (GSK) which lead to abnormal cyclooxygenase-2 (COX-2), activator protein-1 (AP-1), nuclear factor-kappaB (NF-κB) and c-myc expression. Effectiveness of chemopreventive agents reflects their ability to counteract certain upstream signals that leads to genotoxic damage, redox imbalances and other forms of cellular stress. Targeting malfunctioning molecules along the disrupted signal transduction pathway in cancer represent a rational strategy in chemoprevention. NF-κB and AP-1 provide mechanistic links between inflammation and cancer, and moreover regulate tumor angiogenesis and invasiveness, indicating that signaling pathways that mediate their activation provide attractive targets for new chemotherapeutic approaches. Thus cell signaling cascades and their interacting factors have become important targets of chemoprevention and phenolic phytochemicals and plant extracts seem to be promising in this endeavor.
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Affiliation(s)
- Vidushi S Neergheen
- Department of Health Sciences, Faculty of Science, University of Mauritius, Réduit, Mauritius.
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38
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Vinken M, Doktorova T, Decrock E, Leybaert L, Vanhaecke T, Rogiers V. Gap junctional intercellular communication as a target for liver toxicity and carcinogenicity. Crit Rev Biochem Mol Biol 2009; 44:201-22. [PMID: 19635038 DOI: 10.1080/10409230903061215] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Direct communication between hepatocytes, mediated by gap junctions, constitutes a major regulatory platform in the control of liver homeostasis, ranging from hepatocellular proliferation to hepatocyte cell death. Inherent to this pivotal task, gap junction functionality is frequently disrupted upon impairment of the homeostatic balance, as occurs during liver toxicity and carcinogenicity. In the present paper, the deleterious effects of a number of chemical and biological toxic compounds on hepatic gap junctions are discussed, including environmental pollutants, biological toxins, organic solvents, pesticides, pharmaceuticals, peroxides, metals and phthalates. Particular attention is paid to the molecular mechanisms that underlie the abrogation of gap junction functionality. Since hepatic gap junctions are specifically targeted by tumor promoters and epigenetic carcinogens, both in vivo and in vitro, inhibition of gap junction functionality is considered as a suitable indicator for the detection of nongenotoxic hepatocarcinogenicity.
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Affiliation(s)
- Mathieu Vinken
- Department of Toxicology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium.
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39
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Pulukuri S, Sitaramayya A. Retinaldehyde, a Potent Inhibitor of Gap Junctional Intercellular Communication. ACTA ACUST UNITED AC 2009; 11:25-33. [PMID: 15500295 DOI: 10.1080/15419060490471784] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Retinaldehyde and retinoic acid are derivatives of vitamin A, and retinaldehyde is the precursor for the synthesis of retinoic acid, a well-known inhibitor of gap junctional intercellular communication. In this investigation, we asked the question if retinaldehyde has similar effects on gap junctions. Gap junctional intercellular communication was measured by scrape-loading and preloading dye-transfer methods, and studies were carried out mainly on cultured liver epithelial cells. Retinaldehyde was found to be a more potent inhibitor (dye transfer reduced by 50% at 2.8 microM) than retinoic acid (dye transfer reduced by 50% at 30 microM) and glycyrrhetinic acid (dye transfer reduced by 50% at 65 microM). Both the 11-cis and all-trans forms of retinaldehyde were equally effective. Retinaldehyde inhibited dye transfer of both anionic Lucifer yellow and cationic Neurobiotin. Inhibition by retinaldehyde developed in less than two minutes at 50 microM, but unlike the reported case with retinoic acid, recovery was slower, though full. In addition to liver epithelial cells, retinaldehyde inhibited gap junctional communication in lens epithelial cells, retinal pigment epithelial cells and retinal ganglion cells.
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Affiliation(s)
- Sadhona Pulukuri
- Eye Research Institute, Oakland University, Rochester, MI 48309-4480, USA
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40
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Lee KM, Kwon JY, Lee KW, Lee HJ. Ascorbic acid 6-palmitate suppresses gap-junctional intercellular communication through phosphorylation of connexin 43 via activation of the MEK-ERK pathway. Mutat Res 2009; 660:51-56. [PMID: 19026667 DOI: 10.1016/j.mrfmmm.2008.10.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2008] [Revised: 10/01/2008] [Accepted: 10/14/2008] [Indexed: 05/27/2023]
Abstract
Although the health benefits of dietary antioxidants have been extensively studied, their potential negative effects remain unclear. L-Ascorbic acid 6-palmitate (AAP), a synthetic derivative of ascorbic acid (AA), is widely used as an antioxidant and preservative in foods, vitamins, drugs, and cosmetics. Previously, we found that AA exerted an antitumor effect by protecting inhibition of gap-junctional intercellular communication (GJIC), which is closely associated with tumor progression. In this study, we examined whether AAP, an amphipathic derivative of AA, has chemopreventive effects using a GJIC model. AAP and AA exhibited dose-dependent free radical-scavenging activities and inhibited hydrogen peroxide (H(2)O(2))-induced intracellular reactive oxygen species (ROS) production in normal rat liver epithelial cells. Unexpectedly, however, AAP did not protect against the inhibition of GJIC induced by H(2)O(2); instead, it inhibited GJIC synergistically with H(2)O(2). AAP inhibited GJIC in a dose-dependent and reversible manner. This inhibitory effect was not due to the conjugated lipid structure of AAP, as treatment with palmitic acid alone failed to inhibit GJIC under the same conditions. The inhibition of GJIC by AAP was restored in the presence of mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitor U0126, but not in the presence of other signal inhibitors and antioxidant (PKC inhibitors, EGFR inhibitor, NADPH oxidase inhibitor, catalase, vitamin E, or AA), indicating the critical involvement of MEK signaling in the GJIC inhibitory activity of AAP. Phosphorylation of ERK and connexin 43 (Cx43) was observed following AAP treatment, and this was reversed by U0126. These results suggest that the AAP-induced inhibition of GJIC is mediated by the phosphorylation of Cx43 via activation of the MEK-ERK pathway. Taken together, our results indicate that AAP has a potent carcinogenic effect, and that the influence of dietary antioxidants on carcinogenesis may be paradoxical.
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Affiliation(s)
- Kyung Mi Lee
- Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Republic of Korea
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41
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Hwang JW, Jung JW, Lee YS, Kang KS. Indole-3-carbinol prevents H(2)O(2)-induced inhibition of gap junctional intercellular communication by inactivation of PKB/Akt. J Vet Med Sci 2008; 70:1057-63. [PMID: 18981661 DOI: 10.1292/jvms.70.1057] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Indole-3-carbinol (I3C) is a phytochemical found in cruciferous vegetables and possesses a variety of biological and biochemical effects. Despite a wealth of data about the chemopreventive properties of I3C, its effects on gap junctional intercellular communication (GJIC), which is associated with the promotion and progression phases of the multi-stage process of carcinogenesis, has not been studied. In this study, we examined the ability of I3C to prevent H(2)O(2)-induced inhibition of GJIC in WB-F344 rat liver epithelial cells (WB cells). The cells were preincubated with I3C for 48 hr, and then treated with 1 mM H(2)O(2) for 1 hr. We found that I3C could prevent the H(2)O(2)-induced inhibition of GJIC through prevention of the phosphorylated state of gap junction protein connexin 43 (Cx43) phosphorylation. Prevention of GJIC by I3C was dependent upon inactivation of Akt, but not MAPK, although inhibition of GJIC by H(2)O(2) leads to activation of both. Similar to I3C, modulation of Akt activation through the phosphoinositide-3 kinase inhibitor, LY294002, could also prevent H(2)O(2)-induced inhibition of GJIC and phosphorylation of Cx43. Our results suggest that I3C might exert its dietary chemopreventive effects by interfering with the Akt signaling pathway, which appears to be linked to modulating GJIC, a cellular mechanisms regulating cell proliferation, differentiation and apoptosis.
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Affiliation(s)
- Jae-Woong Hwang
- Laboratory of Stem Cell and Tumor Biology, Department of Veterinary Public Health, College of Veterinary Medicine, Seoul National University, Seoul, South Korea
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42
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Upham BL, Bláha L, Babica P, Park JS, Sovadinova I, Pudrith C, Rummel AM, Weis LM, Sai K, Tithof PK, Guzvić M, Vondrácek J, Machala M, Trosko JE. Tumor promoting properties of a cigarette smoke prevalent polycyclic aromatic hydrocarbon as indicated by the inhibition of gap junctional intercellular communication via phosphatidylcholine-specific phospholipase C. Cancer Sci 2008; 99:696-705. [PMID: 18377422 PMCID: PMC3023995 DOI: 10.1111/j.1349-7006.2008.00752.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Inhibition of gap junctional intercellular communication (GJIC) and the activation of intracellular mitogenic pathways are common hallmarks of epithelial derived cancer cells. We previously determined that the 1-methyl and not the 2-methyl isomer of anthracene, which are prominent cigarette smoke components, activated extracellular receptor kinase, and inhibited GJIC in WB-F344 rat liver epithelial cells. Using these same cells, we show that an immediate upstream response to 1-methylanthracene was a rapid (<1 min) release of arachidonic acid. Inhibition of phosphatidylcholine-specific phospholipase C prevented the inhibition of GJIC by 1-methylanthracene. In contrast, inhibition of phosphatidylinositol specific phospholipase C, phospholipase A(2), diacylglycerol lipase, phospholipase D, protein kinase C, and tyrosine protein kinases had no effect on 1-methylanthracene-induced inhibition of GJIC. Inhibition of protein kinase A also prevented inhibition of GJIC by 1-methylanthracene. Direct measurement of phosphatidylcholine-specific phospholipase C and sphingomyelinase indicated that only phosphatidylcholine-specific phospholipase C was activated in response to 1-methylanthracene, while 2-methylanthracene had no effect. 1-methylanthracene also activated p38-mitogen activated protein kinase; however, like extracellular kinase, its activation was not involved in 1-methylanthracene-induced regulation of GJIC, and this activation was independent of phosphatidylcholine-specific phospholipase C. Although mitogen activated protein kinases were activated, Western blot analyzes indicated no change in connexin43 phosphorylation status. Our results indicate that phosphatidylcholine-specific phospholipase C is an important enzyme in the induction of a tumorigenic phenotype, namely the inhibition of GJIC; whereas mitogen activated protein kinases triggered in response to 1-methylanthracene, were not involved in the deregulation of GJIC.
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Affiliation(s)
- Brad L Upham
- Department of Pediatrics & Human Development, Michigan State University, East Lansing, MI 48824, USA.
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43
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Bellei B, Mastrofrancesco A, Briganti S, Aspite N, Ale-Agha N, Sies H, Picardo M. Ultraviolet A induced modulation of gap junctional intercellular communication by P38 MAPK activation in human keratinocytes. Exp Dermatol 2008; 17:115-24. [DOI: 10.1111/j.1600-0625.2007.00662.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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44
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Protective Effect of the Natural Product, Chaetoglobosin K, on Lindane- and Dieldrin-induced Changes in Astroglia: Identification of Activated Signaling Pathways. Pharm Res 2007; 25:1297-308. [DOI: 10.1007/s11095-007-9487-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Accepted: 10/22/2007] [Indexed: 11/26/2022]
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45
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Procházka L, Turánek J, Tesarík R, Knotigová P, Polásková P, Andrysík Z, Kozubík A, Zák F, Sova P, Neuzil J, Machala M. Apoptosis and inhibition of gap-junctional intercellular communication induced by LA-12, a novel hydrophobic platinum(IV) complex. Arch Biochem Biophys 2007; 462:54-61. [PMID: 17466256 DOI: 10.1016/j.abb.2007.03.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 03/20/2007] [Accepted: 03/20/2007] [Indexed: 01/05/2023]
Abstract
A new hydrophobic platinum(IV) complex, LA-12, a very efficient anticancer drug lacking cross-resistance with cisplatin (CDDP), is now being tested in clinical trials. Here we investigated the apoptogenic activity of LA-12 and its effect on gap-junctional intercellular communication (GJIC) in the rat liver epithelial cell line WB-F344. LA-12 induced apoptosis much more efficiently than did CDDP due to a combination of rapid penetration into the cell and attack on DNA, leading to fast activation of p53 and caspase-3. Exposure of WB-F344 cells to LA-12 led to rapid induction of the time- and dose-dependent decrease in GJIC. On the molecular level, loss of GJIC induced by LA-12 was mediated by activation of extracellular signal-regulated kinase (ERK)-1 and ERK-2, as demonstrated by the use of inhibitors of ERK activation. Inhibition of GJIC was linked to rapid hyperphosphorylation of connexin-43 and disappearance of connexon clusters from membranes, which was not observed in the case of CDDP.
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Affiliation(s)
- Lubomír Procházka
- Veterinary Research Institute, Department of Immunology, Brno, Czech Republic
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46
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47
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De Vuyst E, Decrock E, De Bock M, Yamasaki H, Naus CC, Evans WH, Leybaert L. Connexin hemichannels and gap junction channels are differentially influenced by lipopolysaccharide and basic fibroblast growth factor. Mol Biol Cell 2006; 18:34-46. [PMID: 17079735 PMCID: PMC1751325 DOI: 10.1091/mbc.e06-03-0182] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Gap junction (GJ) channels are formed by two hemichannels (connexons), each contributed by the cells taking part in this direct cell-cell communication conduit. Hemichannels that do not interact with their counterparts on neighboring cells feature as a release pathway for small paracrine messengers such as nucleotides, glutamate, and prostaglandins. Connexins are phosphorylated by various kinases, and we compared the effect of various kinase-activating stimuli on GJ channels and hemichannels. Using peptides identical to a short connexin (Cx) amino acid sequence to specifically block hemichannels, we found that protein kinase C, Src, and lysophosphatidic acid (LPA) inhibited GJs and hemichannel-mediated ATP release in Cx43-expressing C6 glioma cells (C6-Cx43). Lipopolysaccharide (LPS) and basic fibroblast growth factor (bFGF) inhibited GJs, but they stimulated ATP release via hemichannels in C6-Cx43. LPS and bFGF inhibited hemichannel-mediated ATP release in HeLa-Cx43 cells, but they stimulated it in HeLa-Cx43 with a truncated carboxy-terminal (CT) domain or in HeLa-Cx26, which has a very short CT. Hemichannel potentiation by LPS was inhibited by blockers of the arachidonic acid metabolism, and arachidonic acid had a potentiating effect like LPS and bFGF. We conclude that GJ channels and hemichannels display similar or oppositely directed responses to modulatory influences, depending on the balance between kinase activity and the activity of the arachidonic acid pathway. Distinctive hemichannel responses to pathological stimulation with LPS or bFGF may serve to optimize the cell response, directed at strictly controlling cellular ATP release, switching from direct GJ communication to indirect paracrine signaling, or maximizing cell-protective strategies.
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Affiliation(s)
- Elke De Vuyst
- *Department of Physiology and Pathophysiology, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Elke Decrock
- *Department of Physiology and Pathophysiology, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Marijke De Bock
- *Department of Physiology and Pathophysiology, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Hiroshi Yamasaki
- Department of Bioscience, School of Science and Technology, Kwansei Gakuin University, Gakuin, Sanda 669-13, Japan
| | - Christian C. Naus
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3; and
| | - W. Howard Evans
- Department of Medical Biochemistry and Immunology, Cardiff University School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Luc Leybaert
- *Department of Physiology and Pathophysiology, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
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48
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Matesic DF, Abifadel DN, Garcia EL, Jann MW. Effect of thioridazine on gap junction intercellular communication in connexin 43-expressing cells. Cell Biol Toxicol 2006; 22:257-68. [PMID: 16685461 DOI: 10.1007/s10565-006-0047-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2005] [Accepted: 03/08/2006] [Indexed: 10/24/2022]
Abstract
Propagation of electrical activity between myocytes in the heart requires gap junction channels, which contribute to coordinated conduction of the heartbeat. Some antipsychotic drugs, such as thioridazine and its active metabolite, mesoridazine, have known cardiac conduction side-effects, which have resulted in fatal or nearly fatal clinical consequences in patients. The physiological mechanisms responsible for these cardiac side-effects are unknown. We tested the effect of thioridazine and mesoridazine on gap junction-mediated intercellular communication between cells that express the major cardiac gap junction subtype connexin 43. Micromolar concentrations of thioridazine and mesoridazine inhibited gap junction-mediated intercellular communication between WB-F344 epithelial cells in a dose-dependent manner, as measured by fluorescent dye transfer. Kinetic analyses demonstrated that inhibition by 10 micromol/L thioridazine occurred within 5 min, achieved its maximal effect within 1 h, and was maintained for at least 24 h. Inhibition was reversible within 1 h upon removal of the drug. Western blot analysis of connexin 43 in a membrane-enriched fraction of WB-F344 cells treated with thioridazine revealed decreased amounts of unphosphorylated connexin 43, and appearance of a phosphorylated connexin 43 band that co-migrated with a "hyperphosphorylated" connexin 43 band present in TPA-inhibited cells. When tested for its effects on cardiomyocytes isolated from neonatal rats, thioridazine decreased fluorescent dye transfer between colonies of beating myocytes. Microinjection of individual cells with fluorescent dye also showed inhibition of dye transfer in thioridazine-treated cells compared to vehicle-treated cells. In addition, thioridazine, like TPA, inhibited rhythmic beating of myocytes within 15 min of application. In light of the fact that the thioridazine and mesoridazine concentrations used in these experiments are in the range of those used clinically in patients, our results suggest that inhibition of gap junction intercellular communication may be one factor contributing to the cardiac side-effects observed in some patients taking these medications.
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Affiliation(s)
- D F Matesic
- Southern School of Pharmacy, Mercer University, Atlanta, Georgia, USA.
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49
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Hakulinen P, Rintala E, Mäki-Paakkanen J, Komulainen H. Altered expression of connexin43 in the inhibition of gap junctional intercellular communication by chlorohydroxyfuranones in WB-F344 rat liver epithelial cells. Toxicol Appl Pharmacol 2006; 212:146-55. [PMID: 16122772 DOI: 10.1016/j.taap.2005.07.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Revised: 07/04/2005] [Accepted: 07/19/2005] [Indexed: 11/17/2022]
Abstract
3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), 3,4-dichloro-5-hydroxy-2(5H)-furanone (MCA), and 3-chloro-4-methyl-5-hydroxy-2(5H)-furanone (MCF) promote foci formation in the two-stage cell transformation assay in vitro. These chlorohydroxyfuranones (CHFs) and their structural congener 3-chloro-4-(chloromethyl)-5-hydroxy-2(5H)-furanone (CMCF) inhibit gap junctional intercellular communication (GJIC) in Balb/c 3T3 mouse fibroblast cells. In the present study, the effects of MX, MCA, CMCF, and MCF on GJIC were evaluated in liver cells (WB-F344 rat liver epithelial cells), the target cells of MX-induced carcinogenicity, using the scrape-loading dye transfer technique. The CHFs inhibited GJIC after 1 h exposure in a concentration-dependent fashion. The order of potency was MX>CMCF approximately MCA>MCF. In terms of the lowest observed effective concentrations, the difference in the potency was about 27-fold (MX 1.875 microM, MCF 50 microM). After a prolonged exposure period (12 h), the inhibition of GJIC by MX and CMCF remained stable, but MCA and MCF exhibited increasing inhibitory effects. After removal of the CHFs, the GJIC slowly recovered. At the transcriptional level, CHFs caused essentially no change in the level of connexin43 (Cx43) mRNA. Preincubation of cells with the protein kinase C (PKC) inhibitor did not modify the response, but the specific MEK 1 inhibitor PD98059 decreased substantially the inhibition of GJIC by all four CHFs. Activation of the mitogen-activated protein kinases (MAPKs) signaling pathway was necessary for inhibition of GJIC. CHFs did not increase the basal phosphorylation state of the Cx43 protein, but all CHFs caused a concentration-dependent degradation of the Cx43 protein. The results indicate that all the studied CHFs inhibit GJIC in WB-F344 cells by altering Cx43 expression.
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Affiliation(s)
- Pasi Hakulinen
- National Public Health Institute, Laboratory of Toxicology, P.O.B. 95, FI-70701 Kuopio, Finland.
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50
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Vine AL, Bertram JS. Upregulation of connexin 43 by retinoids but not by non-provitamin A carotenoids requires RARs. Nutr Cancer 2006; 52:105-13. [PMID: 16091010 DOI: 10.1207/s15327914nc5201_13] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Expression of connexin 43 (Cx43) is correlated with reduced indexes of neoplasia and is upregulated by cancer-preventive retinoids and carotenoids in nontransformed human and murine fibroblasts and keratinocytes. The molecular mechanism of upregulation, however, is poorly understood. Three retinoic acid receptor (RAR) antagonists (Ro 41-5253, BMS453, and BMS493) were capable of suppressing retinoid-induced Cx43 protein expression in 10T1/2 cells. However, Ro 41-5253 did not suppress protein expression by the non-provitamin A carotenoids astaxanthin or lycopene. In contrast, Cx43 induction by astaxanthin but not by a RAR-specific retinoid was inhibited by GW9662, an antagonist of peroxisome proliferator activated receptor-gamma activation. Simultaneous treatment with the maximally effective concentration of a retinoid and with beta-carotene or the non-provitamin A carotenoid astaxanthin resulted in supraadditive upregulation of Cx43 expression, again indicating separate mechanisms of gene regulation by these two cancer preventive agents.
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Affiliation(s)
- Alex L Vine
- Cancer Research Center of Hawaii, University of Hawaii at Manoa, Honolulu 96813, USA
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