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Ke Y, Liu X, Sun Y. Regulatory mechanisms of connexin26. Neuroscience 2025; 570:9-15. [PMID: 39956354 DOI: 10.1016/j.neuroscience.2025.02.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2024] [Revised: 01/21/2025] [Accepted: 02/13/2025] [Indexed: 02/18/2025]
Abstract
Connexins are essential for cellular communication and play a critical role in various physiological processes, including hearing. Connexin26 (Cx26), encoded by the GJB2 gene, is a key component of cochlear gap junctions and is vital for potassium recycling and ATP release-both of which are vital for auditory function. Mutations in GJB2 are the primary cause of sensorineural hearing loss. However, the phenotypic variability observed in individuals with the same mutation suggests the involvement of other complex regulatory factors. While the regulatory mechanisms of Connexin43 have been extensively studied, research on the mechanisms of Cx26 remains limited. This review summarizes the reported regulatory mechanisms of GJB2 from multiple perspectives, both pre- and post-transcription, in an effort to explore ways to regulate connexin expression and provide new insights into gene therapy for diseases caused by alterations in connexin levels.
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Affiliation(s)
- Yihan Ke
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Xiaozhou Liu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yu Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; Institute of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; Hubei Province Clinic Research Center for Deafness and Vertigo, Wuhan 430022, China.
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Li H, Xu CX, Gong RJ, Chi JS, Liu P, Liu XM. How does Helicobacter pylori cause gastric cancer through connexins: An opinion review. World J Gastroenterol 2019; 25:5220-5232. [PMID: 31558869 PMCID: PMC6761244 DOI: 10.3748/wjg.v25.i35.5220] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 08/12/2019] [Accepted: 08/19/2019] [Indexed: 02/06/2023] Open
Abstract
Helicobacter pylori (H. pylori) is a Gram-negative bacterium with a number of virulence factors, such as cytotoxin-associated gene A, vacuolating cytotoxin A, its pathogenicity island, and lipopolysaccharide, which cause gastrointestinal diseases. Connexins function in gap junctional homeostasis, and their downregulation is closely related to gastric carcinogenesis. Investigations into H. pylori infection and the fine-tuning of connexins in cells or tissues have been reported in previous studies. Therefore, in this review, the potential mechanisms of H. pylori-induced gastric cancer through connexins are summarized in detail.
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Affiliation(s)
- Huan Li
- Department of Gastroenterology, the Third Xiangya Hospital of Central South University, Changsha 410013, Hunan Province, China
| | - Can-Xia Xu
- Department of Gastroenterology, the Third Xiangya Hospital of Central South University, Changsha 410013, Hunan Province, China
| | - Ren-Jie Gong
- Department of Gastroenterology, the Third Xiangya Hospital of Central South University, Changsha 410013, Hunan Province, China
| | - Jing-Shu Chi
- Department of Gastroenterology, the Third Xiangya Hospital of Central South University, Changsha 410013, Hunan Province, China
| | - Peng Liu
- Department of Gastroenterology, the Third Xiangya Hospital of Central South University, Changsha 410013, Hunan Province, China
| | - Xiao-Ming Liu
- Department of Gastroenterology, the Third Xiangya Hospital of Central South University, Changsha 410013, Hunan Province, China
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Li H, Xu CX, Gong RJ, Chi JS, Liu P, Liu XM. How does Helicobacter pyloricause gastric cancer through connexins: An opinion review. World J Gastroenterol 2019. [DOI: 10.3748/wjg.v25.i355220] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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Kanlaya R, Thongboonkerd V. Protective Effects of Epigallocatechin-3-Gallate from Green Tea in Various Kidney Diseases. Adv Nutr 2019; 10:112-121. [PMID: 30615092 PMCID: PMC6370267 DOI: 10.1093/advances/nmy077] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 09/12/2018] [Indexed: 12/12/2022] Open
Abstract
Kidney diseases are common health problems worldwide. Various etiologies (e.g., diabetes, hypertension, drug-induced nephrotoxicity, infection, cancers) can affect renal function and ultimately lead to development of chronic kidney disease (CKD) and end-stage renal disease (ESRD). The global rise in number of CKD/ESRD patients during recent years has led to tremendous concern to look for effective strategies to prevent or slow progression of CKD and ESRD. Natural compounds derived from herbs or medicinal plants have gained wide attention for scientific scrutiny to achieve such goals. One of such natural compounds that has been extensively investigated is epigallocatechin-3-gallate (EGCG), a major polyphenol found in the tea plant (Camellia sinensis). A growing body of recent evidence has shown that EGCG may be a promising therapeutic or protective agent in various kidney diseases. This article thus highlights recent progress in medical research on beneficial effects of EGCG against a broad spectrum of kidney diseases, including acute kidney injury, cisplatin-induced nephrotoxicity, kidney stone disease, glomerulonephritis, lupus nephritis, renal cell carcinoma, diabetic nephropathy, CKD, and renal fibrosis. The renoprotective mechanisms are also detailed. Finally, future perspectives of medical research on EGCG and its potential use in clinical practice for treatment and prevention of kidney diseases are discussed.
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Affiliation(s)
- Rattiyaporn Kanlaya
- Medical Proteomics Unit, Office for Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Visith Thongboonkerd
- Medical Proteomics Unit, Office for Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand,Address correspondence to VT (e-mail: or )
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Aasen T, Johnstone S, Vidal-Brime L, Lynn KS, Koval M. Connexins: Synthesis, Post-Translational Modifications, and Trafficking in Health and Disease. Int J Mol Sci 2018; 19:ijms19051296. [PMID: 29701678 PMCID: PMC5983588 DOI: 10.3390/ijms19051296] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 04/20/2018] [Accepted: 04/21/2018] [Indexed: 02/06/2023] Open
Abstract
Connexins are tetraspan transmembrane proteins that form gap junctions and facilitate direct intercellular communication, a critical feature for the development, function, and homeostasis of tissues and organs. In addition, a growing number of gap junction-independent functions are being ascribed to these proteins. The connexin gene family is under extensive regulation at the transcriptional and post-transcriptional level, and undergoes numerous modifications at the protein level, including phosphorylation, which ultimately affects their trafficking, stability, and function. Here, we summarize these key regulatory events, with emphasis on how these affect connexin multifunctionality in health and disease.
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Affiliation(s)
- Trond Aasen
- Translational Molecular Pathology, Vall d'Hebron Institute of Research (VHIR), Autonomous University of Barcelona, CIBERONC, 08035 Barcelona, Spain.
| | - Scott Johnstone
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, P.O. Box 801394, Charlottesville, VI 22908, USA.
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TT, UK.
| | - Laia Vidal-Brime
- Translational Molecular Pathology, Vall d'Hebron Institute of Research (VHIR), Autonomous University of Barcelona, CIBERONC, 08035 Barcelona, Spain.
| | - K Sabrina Lynn
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA.
| | - Michael Koval
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA.
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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Vinken M. Regulation of connexin signaling by the epigenetic machinery. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1859:262-8. [PMID: 26566120 DOI: 10.1016/j.bbagrm.2015.11.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2015] [Revised: 11/03/2015] [Accepted: 11/06/2015] [Indexed: 12/31/2022]
Abstract
Connexins and their channels are involved in the control of all aspects of the cellular life cycle, ranging from cell growth to cell death, by mediating extracellular, intercellular and intracellular communication. These multifaceted aspects of connexin-related cellular signaling obviously require strict regulation. While connexin channel activity is mainly directed by posttranslational modifications, connexin expression as such is managed by classical cis/trans mechanisms. Over the past few years, it has become clear that connexin production is equally dictated by epigenetic actions. This paper provides an overview of the role of major determinants of the epigenome, including DNA methylation, histone acetylation and microRNA species, in connexin expression.
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Affiliation(s)
- Mathieu Vinken
- Vrije Universiteit Brussel, Department of In Vitro Toxicology and Dermato-Cosmetology, Building G, Room G226, Laarbeeklaan 103, B-1090 Brussels, Belgium.
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Schalper KA, Carvajal-Hausdorf D, Oyarzo MP. Possible role of hemichannels in cancer. Front Physiol 2014; 5:237. [PMID: 25018732 PMCID: PMC4073485 DOI: 10.3389/fphys.2014.00237] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 06/09/2014] [Indexed: 12/12/2022] Open
Abstract
In humans, connexins (Cxs) and pannexins (Panxs) are the building blocks of hemichannels. These proteins are frequently altered in neoplastic cells and have traditionally been considered as tumor suppressors. Alteration of Cxs and Panxs in cancer cells can be due to genetic, epigenetic and post-transcriptional/post-translational events. Activated hemichannels mediate the diffusional membrane transport of ions and small signaling molecules. In the last decade hemichannels have been shown to participate in diverse cell processes including the modulation of cell proliferation and survival. However, their possible role in tumor growth and expansion remains largely unexplored. Herein, we hypothesize about the possible role of hemichannels in carcinogenesis and tumor progression. To support this theory, we summarize the evidence regarding the involvement of hemichannels in cell proliferation and migration, as well as their possible role in the anti-tumor immune responses. In addition, we discuss the evidence linking hemichannels with cancer in diverse models and comment on the current technical limitations for their study.
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Affiliation(s)
- Kurt A Schalper
- Servicio Anatomía Patológica, Clínica Alemana de Santiago, Facultad de Medicina Clinica Alemana Universidad del Desarrollo Santiago, Chile ; Department of Pathology, Yale School of Medicine New Haven, CT, USA
| | | | - Mauricio P Oyarzo
- Servicio Anatomía Patológica, Clínica Alemana de Santiago, Facultad de Medicina Clinica Alemana Universidad del Desarrollo Santiago, Chile
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Nielsen MS, Axelsen LN, Sorgen PL, Verma V, Delmar M, Holstein-Rathlou NH. Gap junctions. Compr Physiol 2013; 2:1981-2035. [PMID: 23723031 DOI: 10.1002/cphy.c110051] [Citation(s) in RCA: 311] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease.
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Affiliation(s)
- Morten Schak Nielsen
- Department of Biomedical Sciences and The Danish National Research Foundation Centre for Cardiac Arrhythmia, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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9
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Sato A, Sekine M, Kobayashi M, Virgona N, Ota M, Yano T. Induction of the connexin 32 gene by epigallocatechin-3-gallate potentiates vinblastine-induced cytotoxicity in human renal carcinoma cells. Chemotherapy 2013; 59:192-9. [PMID: 24335094 DOI: 10.1159/000354715] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 07/26/2013] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIM Enforced expression of the connexin (Cx) 32 gene, a member of the gap junction gene family and a tumor suppressor gene in human renal cell carcinoma (RCC), enhanced vinblastine (VBL)-induced cytotoxicity in RCC cells due to suppression of multidrug resistance 1 (MDR1) expression. Furthermore, in RCC the Cx32 gene is silenced by hypermethylation of CpG islands in a promoter region of the Cx gene. In this study, we investigated if the green tea polyphenol epigallocatechin-3-gallate (EGCG) could enhance susceptibility of RCC cells (Caki-1, a human metastatic RCC cell) to VBL. METHODS The effects of EGCG on Caki-1 cells were estimated by WST-1 (cell viability), real-time RT-PCR (mRNA level) and immunoblotting (protein level). We estimated the methylation status in the promoter region of the Cx32 gene in RCC cells by methylation-specific PCR. Each protein function was inhibited by small interfering RNA (siRNA) and specific inhibitors. RESULTS The EGCG treatment elicited significant upregulation of Cx32 in Caki-1 cells, and the induction of the Cx led to the suppression of MDR1 mRNA expression through inactivation of Src and subsequent activation of c-Jun NH2-terminal kinase (JNK). Chemical sensitivity to VBL in Caki-1 cells was increased by EGCG pretreatment, and this effect was abrogated by siRNA-mediated knockdown of Cx32. CONCLUSION This study suggests that the restoration of Cx32 by EGCG pretreatment improves chemical tolerance on VBL in Caki-1 cells via the inactivation of Src and the activation of JNK.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- Carcinoma, Renal Cell/metabolism
- Carcinoma, Renal Cell/pathology
- Catechin/analogs & derivatives
- Catechin/pharmacology
- Cell Line, Tumor
- Cell Survival/drug effects
- Connexins/antagonists & inhibitors
- Connexins/genetics
- Connexins/metabolism
- DNA Methylation
- Humans
- Promoter Regions, Genetic
- RNA Interference
- RNA, Messenger/metabolism
- RNA, Small Interfering/metabolism
- Up-Regulation/drug effects
- Vinblastine/toxicity
- Gap Junction beta-1 Protein
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Affiliation(s)
- Ayami Sato
- Research Group on Nutritional Sciences, Faculty of Life Sciences, Toyo University, Itakura, Japan
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Pointis G, Gilleron J, Carette D, Segretain D. Testicular connexin 43, a precocious molecular target for the effect of environmental toxicants on male fertility. SPERMATOGENESIS 2011; 1:303-317. [PMID: 22332114 DOI: 10.4161/spmg.1.4.18392] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 10/10/2011] [Accepted: 10/10/2011] [Indexed: 02/08/2023]
Abstract
Many recent epidemiological, clinical and experimental findings support the hypothesis that environmental toxicants are responsible for the increasing male reproductive disorders (congenital malformations, declining sperm counts and testicular cancer) over the past 20 years. It has also been reported that exposure to these toxicants, during critical periods of development (fetal and neonatal), represents a more considerable risk for animals and humans than exposure during adulthood. However, the molecular targets for these chemicals have not been clearly identified. Recent studies showed that a family of transmembranous proteins, named connexins, regulates numerous physiological processes involved in testicular development and function, such as Sertoli and germ cell proliferation, differentiation, germ cell migration and apoptosis. In the testis, knockout strategy revealed that connexin 43, the predominant connexin in this organ, is essential for spermatogenesis. In addition, there is evidence that many environmental toxicants could alter testicular connexin 43 by dysregulation of numerous mechanisms controlling its function. In the present work, we propose first to give an overview of connexin expression and intercellular gap junction coupling in the developing fetal and neonatal testes. Second, we underline the impact of maternally chemical exposure on connexin 43 expression in the perinatal developing testis. Lastly, we attempt to link this precocious effect to male offspring fertility.
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Takano Y, Iwata H, Yano Y, Miyazawa M, Virgona N, Sato H, Ueno K, Yano T. Up-regulation of connexin 32 gene by 5-aza-2'-deoxycytidine enhances vinblastine-induced cytotoxicity in human renal carcinoma cells via the activation of JNK signalling. Biochem Pharmacol 2010; 80:463-70. [PMID: 20510207 DOI: 10.1016/j.bcp.2010.05.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 05/10/2010] [Accepted: 05/17/2010] [Indexed: 11/17/2022]
Abstract
Enforced expression of connexin (Cx) 32 gene, a member of gap junction gene family and a tumor suppressor gene in human renal cell carcinoma (RCC), enhanced vinblastine (VBL)-induced cytotoxicity on RCC cells, due to the suppression of multidrug resistance 1 (MDR1) gene product, P-glycoprotein (P-gp). Also, Cx32 gene in RCC is silenced by hypermethylation of CpG islands in a promoter region of the Cx gene. In this study, we investigated if a DNA demethylating agent, 5-aza-2'-deoxycytidine (5-Aza) could enhance susceptibility of RCC cells (Caki-1) to VBL. We found that 5-Aza treatment up-regulated Cx32 in Caki-1 cells, and the induction of the Cx led to the suppression of P-gp through inhibition of Src and subsequent activation of c-Jun NH(2)-terminal kinase (JNK). Moreover, increased transcription activity of c-Jun by the JNK activation contributed to the down-regulation of MDR1, thus indicating a central role of JNK signalling to suppress P-gp level in 5-Aza-treated Caki-1 cells. Chemical sensitivity to VBL in Caki-1 cells was increased by 5-Aza pre-treatment, and this effect was abrogated by short interfering RNA (siRNA)-mediated knockdown of Cx32. Furthermore, co-treatment of 5-Aza or a P-gp inhibitor with VBL drastically enhanced JNK activation comparing to only VBL treatment in Caki-1 cells. These results suggest that the restoration of Cx32 by 5-Aza pre-treatment improves chemical tolerance on VBL in Caki-1 cells and that the JNK activation is a key factor to induce the effect.
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Affiliation(s)
- Y Takano
- National Institute of Health and Nutrition, Tokyo, Japan.
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Snykers S, Henkens T, De Rop E, Vinken M, Fraczek J, De Kock J, De Prins E, Geerts A, Rogiers V, Vanhaecke T. Role of epigenetics in liver-specific gene transcription, hepatocyte differentiation and stem cell reprogrammation. J Hepatol 2009; 51:187-211. [PMID: 19457566 DOI: 10.1016/j.jhep.2009.03.009] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Controlling both growth and differentiation of stem cells and their differentiated somatic progeny is a challenge in numerous fields, from preclinical drug development to clinical therapy. Recently, new insights into the underlying molecular mechanisms have unveiled key regulatory roles of epigenetic marks driving cellular pluripotency, differentiation and self-renewal/proliferation. Indeed, the transcription of genes, governing cell-fate decisions during development and maintenance of a cell's differentiated status in adult life, critically depends on the chromatin accessibility of transcription factors to genomic regulatory and coding regions. In this review, we discuss the epigenetic control of (liver-specific) gene-transcription and the intricate interplay between chromatin modulation, including histone (de)acetylation and DNA (de)methylation, and liver-enriched transcription factors. Special attention is paid to their role in directing hepatic differentiation of primary hepatocytes and stem cells in vitro.
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Affiliation(s)
- Sarah Snykers
- Department of Toxicology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium.
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Vinken M, De Rop E, Decrock E, De Vuyst E, Leybaert L, Vanhaecke T, Rogiers V. Epigenetic regulation of gap junctional intercellular communication: More than a way to keep cells quiet? Biochim Biophys Acta Rev Cancer 2009; 1795:53-61. [DOI: 10.1016/j.bbcan.2008.08.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 08/14/2008] [Accepted: 08/18/2008] [Indexed: 02/07/2023]
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Sato H, Hagiwara H, Senba H, Fukumoto K, Nagashima Y, Yamasaki H, Ueno K, Yano T. The inhibitory effect of connexin 32 gene on metastasis in renal cell carcinoma. Mol Carcinog 2008; 47:403-9. [PMID: 18058801 DOI: 10.1002/mc.20396] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We have previously reported that connexin (Cx) 32 gene, a member of gap junctions, was specifically downregulated in human renal cell carcinoma (RCC) and it acts as a tumor suppressor against RCC. Because there is no standard therapy for advanced RCC, we investigated the anti-metastatic effect of Cx32 to seek a possibility of new RCC therapy. In this study, we used human metastatic RCC cell (Caki-1), and established Cx32-expressed cell clone (Caki-1T) or only mock-transfected cell clone (Caki-1W). For experimental production of metastases, the cells were injected into the lateral tail vein of SCID mice. Seventy days after inoculation, metastatic colonies were observed in Caki-1W inoculated group, though none of them were in Caki-1T inoculated group. The plasma VEGF concentration was significantly lower in Caki-1T group compared to Caki-1W group. To investigate where Cx32 effects on, we also tried in vitro analysis and found that the malignant phenotypes involving metastasis steps were significantly decreased in Caki-1T under hypoxia, a mimic condition of internal tumor environment. After hypoxia treatment, the protein level of HIF-2alpha, which plays main role for hypoxia adaptation, was observed to increase in Caki-1W, whereas no expression was observed in Caki-1T. We investigated the activation of Src, which is required for stabilization of HIF-2alpha, is suppressed in Caki-1T compared to Caki-1W. These results suggest that Cx32 inhibits hypoxia adaptation governed by HIF-2alpha, and this may help to reduce the metastasis of RCC cells.
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Affiliation(s)
- Hiromi Sato
- Project for Complementary Factors, National Institute of Health and Nutrition, Shinjuku-ku, Tokyo, Japan
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Hagiwara H, Sato H, Ohde Y, Takano Y, Seki T, Ariga T, Hokaiwado N, Asamoto M, Shirai T, Nagashima Y, Yano T. 5-Aza-2'-deoxycytidine suppresses human renal carcinoma cell growth in a xenograft model via up-regulation of the connexin 32 gene. Br J Pharmacol 2008; 153:1373-81. [PMID: 18264126 PMCID: PMC2437922 DOI: 10.1038/bjp.2008.17] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 12/10/2007] [Accepted: 12/18/2007] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND AND PURPOSE The connexin (Cx) 32 gene, a member of the gap junction gene family, acts as a tumour suppressor gene in human renal cell carcinoma (RCC) and is down-regulated by the hypermethylation of CpG islands in a promoter region of the Cx gene. The current study investigated whether the restoration of Cx32 silenced by hypermethylation in RCC by a DNA demethylating agent could be an effective treatment against RCC. EXPERIMENTAL APPROACH Using nude mice bearing Caki-1 cells (a human metastatic RCC cell line), the effects of 5-aza-2'-deoxycytidine (5-aza-CdR), a DNA demethylase inhibitor, on Cx32 mRNA expression and tumour growth were examined by RT-PCR, and by measuring tumour weight and volume. Cx32 expression in Caki-1 tumours was inhibited by Cx32 short interfering (si) RNA, and the effect of siRNA on 5-aza-CdR-dependent suppression of tumour growth in nude mice was evaluated. KEY RESULTS 5-aza-CdR treatment inhibited the growth of Caki-1 cells in nude mice by 70% and increased 7-fold the level of Cx32 mRNA. The intratumour injection of Cx32 siRNA almost totally inhibited the expression of Cx32 mRNA and significantly reduced the suppression of tumour growth in 5-aza-CdR-treated nude mice. CONCLUSIONS AND IMPLICATIONS 5-aza-CdR suppressed the growth of Caki-1 tumours in a xenograft model, by restoring Cx32 expression. This finding suggests that treatment with 5-aza-CdR could be a new effective therapy against human metastatic RCC and that Cx32 could be a potential target for the treatment of RCC.
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Affiliation(s)
- H Hagiwara
- Project for Complementary Factors, National Institute of Health and Nutrition Shinjuku, Tokyo, Japan
| | - H Sato
- Project for Complementary Factors, National Institute of Health and Nutrition Shinjuku, Tokyo, Japan
- Graduate School of Pharmaceutical Sciences, Chiba University Chuo-ku, Chiba, Japan
| | - Y Ohde
- Project for Complementary Factors, National Institute of Health and Nutrition Shinjuku, Tokyo, Japan
- College of Bioresource Sciences, Nihon University Fujisawa, Kanagawa, Japan
| | - Y Takano
- Project for Complementary Factors, National Institute of Health and Nutrition Shinjuku, Tokyo, Japan
- Graduate School of Pharmaceutical Sciences, Chiba University Chuo-ku, Chiba, Japan
| | - T Seki
- College of Bioresource Sciences, Nihon University Fujisawa, Kanagawa, Japan
| | - T Ariga
- College of Bioresource Sciences, Nihon University Fujisawa, Kanagawa, Japan
| | - N Hokaiwado
- Department of Experimental Pathology and Tumour Biology, Nagoya City University Graduate School of Medical Science Mizuho-cho, Mizuho-ku, Nagoya, Japan
| | - M Asamoto
- Department of Experimental Pathology and Tumour Biology, Nagoya City University Graduate School of Medical Science Mizuho-cho, Mizuho-ku, Nagoya, Japan
| | - T Shirai
- Department of Experimental Pathology and Tumour Biology, Nagoya City University Graduate School of Medical Science Mizuho-cho, Mizuho-ku, Nagoya, Japan
| | - Y Nagashima
- Department of Molecular Pathology, Yokohama City University Graduate School of Medicine Kanazawa-ku, Yokohama, Japan
| | - T Yano
- Project for Complementary Factors, National Institute of Health and Nutrition Shinjuku, Tokyo, Japan
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16
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Vinken M, Henkens T, De Rop E, Fraczek J, Vanhaecke T, Rogiers V. Biology and pathobiology of gap junctional channels in hepatocytes. Hepatology 2008; 47:1077-88. [PMID: 18058951 DOI: 10.1002/hep.22049] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The present review provides the state of the art of the current knowledge concerning gap junctional channels and their roles in liver functioning. In the first part, we summarize some relevant biochemical properties of hepatic gap junctional channels, including their structure and regulation. In the second part, we discuss the involvement of gap junctional channels in the occurrence of liver cell growth, liver cell differentiation, and liver cell death. We further exemplify their relevance in hepatic pathophysiology. Finally, a number of directions for future liver gap junctional channel research are proposed, and the up-regulation of gap junctional channel activity as a novel strategy in (liver) cancer therapy is illustrated.
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Affiliation(s)
- Mathieu Vinken
- Department of Toxicology, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090 Brussels, Belgium.
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17
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Yi ZC, Wang H, Zhang GY, Xia B. Downregulation of connexin 43 in nasopharyngeal carcinoma cells is related to promoter methylation. Oral Oncol 2007; 43:898-904. [PMID: 17306607 DOI: 10.1016/j.oraloncology.2006.11.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2006] [Revised: 11/01/2006] [Accepted: 11/01/2006] [Indexed: 12/13/2022]
Abstract
Down-regulation of Cx43 expression had been shown to occur in nasopharyngeal carcinoma cells. The present study was undertaken to estimate if methylation of the promoter region in Cx43 gene was responsible for the repression of Cx43 expression in the CNE-1 nasopharyngeal carcinoma cells. Calcein transfer and lucifer yellow transfer were detected to evaluate gap junction intercellular communication (GJIC) in CNE-1 cells. It was found that the control CNE-1 cells showed no fluorescent dye transfer. After treatment with DNA methyltransferase inhibitor 5-aza-CdR, fluorescent dye transfer between cells became obvious. RT-PCR and Western blot were performed to determine the expression of Cx43 gene. The control CNE-1 cells showed a low expression level of Cx43, whereas 5-aza-CdR-treated CNE-1 cells showed an enhanced level of Cx43 expression. Methylation-sensitive restriction enzyme and PCR analysis showed that the methylation of the Cx43 gene promoter region occurred in CNE-1 cells. In addition, treatment with 5-aza-CdR inhibited the growth (including anchorage-independent growth) of CNE-1 cells, and resulted in an accumulation of cells in G0/G1 phase. These results indicate the promoter methylation as an important role in inactivation of Cx43 in CNE-1 cells.
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Affiliation(s)
- Zong-Chun Yi
- Department of Biological Engineering, Beijing University of Aeronautics and Astronautics, 37 Xueyuan Road, Beijing 100083, PR China.
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18
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Sato H, Hagiwara H, Ohde Y, Senba H, Virgona N, Yano T. Regulation of renal cell carcinoma cell proliferation, invasion and metastasis by connexin 32 gene. J Membr Biol 2007; 216:17-21. [PMID: 17565422 DOI: 10.1007/s00232-007-9020-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Accepted: 04/04/2007] [Indexed: 12/27/2022]
Abstract
Gap junctions composed of connexin (Cx), a large protein family with a number of subtypes, are a main apparatus to maintain cellular homeostasis in many organs. Gap junctional intercellular communication (GJIC) is actively involved in all aspects of the cellular life cycle, ranging from cell growth to cell death. It is also known that the Cx gene acts as a tumor-suppressor due to the maintenance of cellular homeostasis via GJIC. In addition to this function, recent data show that the GJIC-independent function of Cx gene contributes to the tumor-suppressive effect of the gene with specificity to certain cells. With respect to the tumor-suppressive effects, Cx genes acts as tumor-suppressors in primary cancers, but the effects are still conflicting in invasive and metastatic cancers. We have previously reported that Cx32 is specifically downregulated in human renal cell carcinoma (RCC) cell lines as well as cancerous regions when compared to normal regions in kidneys. In recent studies, we have also reported that Cx32 suppresses growth, invasion and metastasis of RCC cells. In this minireview, we refer to a new aspect of Cx32-dependent functions against cell proliferation, invasion and metastasis in RCC cells, especially in a GJIC-independent manner.
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Affiliation(s)
- H Sato
- Project for Complementary Factors, National Institute of Health and Nutrition, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8636, Japan
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19
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Vinken M, Papeleu P, Snykers S, De Rop E, Henkens T, Chipman JK, Rogiers V, Vanhaecke T. Involvement of cell junctions in hepatocyte culture functionality. Crit Rev Toxicol 2006; 36:299-318. [PMID: 16809101 DOI: 10.1080/10408440600599273] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In liver, like in other multicellular systems, the establishment of cellular contacts is a prerequisite for normal functioning. In particular, well-defined cell junctions between hepatocytes, including adherens junctions, desmosomes, tight junctions, and gap junctions, are known to play key roles in the performance of liver-specific functionality. In a first part of this review article, we summarize the current knowledge concerning cell junctions and their roles in hepatic (patho)physiology. In a second part, we discuss their relevance in liver-based in vitro modeling, thereby highlighting the use of primary hepatocyte cultures as suitable in vitro models for preclinical pharmaco-toxicological testing. We further describe the actual strategies to regain and maintain cell junctions in these in vitro systems over the long-term.
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Affiliation(s)
- Mathieu Vinken
- Department of Toxicology, Vrije Universiteit Brussel (VUB), Brussels, Belgium.
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20
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Hagiwara H, Sato H, Shirai S, Kobayashi S, Fukumoto K, Ishida T, Seki T, Ariga T, Yano T. Connexin 32 down-regulates the fibrinolytic factors in metastatic renal cell carcinoma cells. Life Sci 2006; 78:2249-54. [PMID: 16289236 DOI: 10.1016/j.lfs.2005.09.036] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Accepted: 09/13/2005] [Indexed: 11/17/2022]
Abstract
Fibrinolytic factors have an important role in tumor progression through the degradation of extracellular matrix. The increased levels of urokinase-type plasminogen activator (uPA), uPA-receptor (uPAR) and type-1 PA inhibitor (PAI-1) are reported in human renal cell carcinoma (RCC). Connexin (Cx) gene, a member of gap junction, is known to act as a tumor suppressor gene. We have reported that Cx32 improves malignant phenotypes of metastatic RCC cells via the inhibition of Src-dependent signaling. In this study, we examined the effect of expression of Cx32 gene on the production of uPA, uPAR and PAI-1, and on the induction of PAI-1 stimulated by hypoxia in a human metastatic RCC cell line, Caki-1 cells. Cx32 expression decreased both mRNA level and production of PAI-1, uPA and uPAR in Caki-1 cells. Cx32 also decreased hypoxia-inducible factor (HIF)-1alpha and HIF-2alpha mRNA level. PP1, a Src inhibitor, significantly decreased PAI-1, uPA, uPAR and HIF-alpha mRNA levels in Caki-1 cells. Furthermore, Cx32 suppressed the induction of HIF-2alpha protein in Caki-1 cells under hypoxia. PAI-1 mRNA level in Cx32-transfected Caki-1 cells was lower than that of mock transfectant under hypoxic conditions. These results suggest that Cx32 might reduce PAI-1, uPA and uPAR production in metastatic RCC cells via the inhibition of Src-dependent induction of HIF-1alpha and HIF-2alpha gene expression and that Cx32 might suppress hypoxia-inducible gene expression under hypoxic conditions.
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Affiliation(s)
- Hiromi Hagiwara
- Department of Food Science Research for Health, National Institute of Health and Nutrition, Toyama, Shinjuku, Tokyo, Japan.
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21
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Mesnil M, Crespin S, Avanzo JL, Zaidan-Dagli ML. Defective gap junctional intercellular communication in the carcinogenic process. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2005; 1719:125-45. [PMID: 16359943 DOI: 10.1016/j.bbamem.2005.11.004] [Citation(s) in RCA: 253] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2005] [Revised: 11/07/2005] [Accepted: 11/10/2005] [Indexed: 01/07/2023]
Abstract
Gap junctions are membrane structures made of intercellular channels which permit the diffusion from cytoplasm to cytoplasm of small hydrophilic molecules. Nearly 40 years ago, the loss of functional gap junctions has been described in cancer cells and led to the hypothesis that such type of intercellular communication is involved in the carcinogenesis process. From this time, a lot of data has been accumulated confirming that gap junctions are frequently decreased or absent in cancer cells whatever their tissue and species origins. Here, we review such data by insisting on the possible links existing between altered gap-junctional intercellular communication capacity (or the altered expression of their constitutive proteins, the connexins) and the stages of cancer progression in various cancer models. Then, we analyse particular aspects of the disturbance of connexin-mediated communication in cancer such as the cytoplasmic localization of connexins, the lack of heterologous communication between cancer cells and normal cells, the role of connexin gene mutations in cancer. In a separate part of the review, we also analyse the disturbance of gap-junctional intercellular communication during the late stages of cancer (invasion and metastasis processes).
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Affiliation(s)
- Marc Mesnil
- Equipe Interactions et Communications Cellulaires, Institut de Physiologie et Biologie Cellulaires, CNRS-UMR 6187, Université de Poitiers, 40 avenue du Recteur Pineau, 86022 Poitiers cedex, France.
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22
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Oyamada M, Oyamada Y, Takamatsu T. Regulation of connexin expression. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2005; 1719:6-23. [PMID: 16359940 DOI: 10.1016/j.bbamem.2005.11.002] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Revised: 10/29/2005] [Accepted: 11/02/2005] [Indexed: 01/22/2023]
Abstract
Gap junctions contain cell-cell communicating channels that consist of multimeric proteins called connexins and mediate the exchange of low-molecular-weight metabolites and ions between contacting cells. Gap junctional communication has long been hypothesized to play a crucial role in the maintenance of homeostasis, morphogenesis, cell differentiation, and growth control in multicellular organisms. The recent discovery that human genetic disorders are associated with mutations in connexin genes and experimental data on connexin knockout mice have provided direct evidence that gap junctional communication is essential for tissue functions and organ development. Thus far, 21 human genes and 20 mouse genes for connexins have been identified. Each connexin shows tissue- or cell-type-specific expression, and most organs and many cell types express more than one connexin. Cell coupling via gap junctions is dependent on the specific pattern of connexin gene expression. This pattern of gene expression is altered during development and in several pathological conditions resulting in changes of cell coupling. Connexin expression can be regulated at many of the steps in the pathway from DNA to RNA to protein. However, transcriptional control is one of the most important points. In this review, we summarize recent knowledge on transcriptional regulation of connexin genes by describing the structure of connexin genes and transcriptional factors that regulate connexin expression.
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Affiliation(s)
- Masahito Oyamada
- Department of Pathology and Cell Regulation, Kyoto Prefectural University of Medicine, Kawaramachi Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
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Sumiko S, Hiromi H, Hiromi S, Keiko F, Shigeto K, Taiichiro S, Toyohiko A, Kiyokazu H, Hiroshi Y, Tomohiro Y. Prevention of renal cell carcinoma from hemodialysis patients by regulating epigenetic factors. Kidney Int 2005; 67:2506-7. [PMID: 15882304 DOI: 10.1111/j.1523-1755.2005.360_6.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Fujimoto E, Sato H, Shirai S, Nagashima Y, Fukumoto K, Hagiwara H, Negishi E, Ueno K, Omori Y, Yamasaki H, Hagiwara K, Yano T. Connexin32 as a tumor suppressor gene in a metastatic renal cell carcinoma cell line. Oncogene 2005; 24:3684-90. [PMID: 15782139 DOI: 10.1038/sj.onc.1208430] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2004] [Revised: 12/03/2004] [Accepted: 12/06/2004] [Indexed: 02/07/2023]
Abstract
Connexin genes expressing gap junction proteins have tumor-suppressive effects on primary cancers with certain cell specificity, but the suppressive effects on metastatic cancers are still conflicting. In this study, we show that connexin32 (Cx32) has a strong tumor-suppressive effect on a human metastatic renal cell carcinoma cell line (Caki-1 cell). Cx32 expression in Caki-1 cells reduced in vitro malignant phenotypes of the cells such as anchorage independency and invasion capacity. Furthermore, the Cx32 expression drastically reduced the development of Caki-1 cells in nude mice. We also determined that Cx32 reduced the malignant phenotypes in Caki-1 cells mainly through the inactivation of Src signaling. Especially, Cx32-dependent inactivation of Src decreased the production of vascular epithelial growth factor (VEGF) via the suppression of signal transducers and activators of transcription 3 (Stat3) activation, and we confirmed this result using short interfering RNA. In nude mice, Cx32-transfected Caki-1 cells showed lower serum level of VEGF comparing mock transfectant, and the development of the cells in nude mice positively related to the VEGF level. These data suggest that Cx32 acts as a tumor suppressor gene in Caki-1 cells and that the tumor-suppressive effect partly depends on the inhibition of Src-Stat3-VEGF signal pathway.
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Affiliation(s)
- Eriko Fujimoto
- Department of Food Science Research for Health, National Institute of Health and Nutrition, 1-23-1 Toyama, Shinjuku, 162-8636 Tokyo, Japan
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Fujimoto E, Satoh H, Negishi E, Ueno K, Nagashima Y, Hagiwara K, Yamasaki H, Yano T. Negative growth control of renal cell carcinoma cell by connexin 32: possible involvement of Her-2. Mol Carcinog 2004; 40:135-42. [PMID: 15224345 DOI: 10.1002/mc.20025] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Connexin (Cx) genes have negative growth effects on tumor cells with certain cell specificity. We have previously reported that Cx32 is specifically downregulated in human renal cell carcinoma cell (RCC) lines as well as cancerous regions of kidneys and that the Cx is expressed in the progenitor cells of the carcinoma. However, the precise role of Cx32 in growth control of RCC cells remains unknown. In this study, we examined whether Cx32 could act in growth control against a human RCC cell, Caki-2 cell. In order to estimate the cell growth control, we established Caki-2 cells that have stable expression of Cx32 genes. Cx32 expression in Caki-2 cells induced contact inhibition of growth and reduced anchorage-independent growth ability, but did not significantly affect lag phase growth rates. This growth control by Cx32 was dependent on the inhibition of the cell-cycle transition from G1 to S phase at high cell density, and the inhibition of the cell-cycle transition related to the suppression of Her-2 activation. Furthermore, the suppression of Cx32 expression in Caki-2 cells by short interfering RNA induced the activation of Her-2. These data suggest that Cx32 has negative growth control of Caki-2 cells, partly due to the inhibition of the Her-2 activation.
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Affiliation(s)
- Eriko Fujimoto
- Faculty of Pharmaceutical Sciences, Chiba University, Chiba, Japan
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26
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Yano T, Ito F, Kobayashi K, Yonezawa Y, Suzuki K, Asano R, Hagiwara K, Nakazawa H, Toma H, Yamasaki H. Hypermethylation of the CpG island of connexin 32, a candiate tumor suppressor gene in renal cell carcinomas from hemodialysis patients. Cancer Lett 2004; 208:137-42. [PMID: 15142671 DOI: 10.1016/j.canlet.2003.11.029] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2003] [Revised: 11/14/2003] [Accepted: 11/21/2003] [Indexed: 10/26/2022]
Abstract
Long duration of patients on hemodialysis is a large risk for the development of renal cell carcinoma (RCC) compared to general patients. However, the carcinogenic process is still unclear. On the other hand, we have reported that connexin (Cx) 32, a molecule of gap junction, is a new tumor suppressor gene in human RCC. In this study, we investigated the clinical significance of methylation-dependent silencing of Cx32 gene in the development of the RCC from the hemodialysis patients. As the result, we found that the inactivation of Cx32 through hypermethylation of the promoter regions frequently occurred in non-cancerous regions as well as cancerous regions of kidneys from hemodialysis patients. However, the hypermethylation of Cx32 occurred only in cancerous regions but not non-cancerous regions of kidneys from the general patients without hemodialysis. Furthermore, the hypermethylation of RASSAF1A, a representative tumor suppressor gene in human RCC, occurred in cancerous regions but not non-cancerous regions of kidneys from the hemodialysis and general patients. These results suggest that Cx32 is a promising tumor suppressor gene relating to the early stage of renal carcinogenesis in the hemodialysis patients.
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Affiliation(s)
- Tomohiro Yano
- Department of Food Science Research for Health, National Institute of Health and Nutrition, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8636, Japan.
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Saito T, Tanaka R, Wataba K, Kudo R, Yamasaki H. Overexpression of estrogen receptor-alpha gene suppresses gap junctional intercellular communication in endometrial carcinoma cells. Oncogene 2004; 23:1109-16. [PMID: 14762440 DOI: 10.1038/sj.onc.1207215] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2003] [Accepted: 09/04/2003] [Indexed: 11/08/2022]
Abstract
Stimulation of the endometrium by estrogens without the differentiating effect of progestins is the primary etiological factor associated with the development of endometrial hyperplasia and adenocarcinoma. However, the correlation between sex steroids and gap junctional intercellular communication (GJIC), which is considered to play an important role in the control of cell growth and differentiation, is not well known in endometrial carcinoma. In this study, we focused on the influence of estrogen and its receptor in connexin (Cx) expression and GJIC in endometrial carcinoma cells, established stable clone IK-ER1 overexpressing ER-alpha to transfect the expression vector and analysed them in various hormonal conditions. The growth of IK-ER1 was accelerated by 17beta-estradiol and the acceleration of the 5-bromo-25-deoxyuridine labeling index was observed. GJIC was assayed by scoring the number of dye-coupled cells after microinjection of single cells with Lucifer-Yellow, and subcellular localization of Cx26 and Cx32 was analysed by immunocytochemistry. In the presence of estradiol, dye-coupled cells of IK-ER1 were significantly reduced compared to those without estradiol and the reduction was completely inhibited by adding ICI182.780, a pure antiestrogen substrate. Cxs were detected as only small spots by immunocytochemistry, and Western blotting showed that the expression was decreased. These results suggest that activation of ER-alpha by estrogen results in tumor progression by stimulating cell growth and suppressing GJIC via suppression of the expression of Cxs in endometrial carcinogenesis.
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Affiliation(s)
- Tsuyoshi Saito
- Department of Obstetrics and Gynecology, Sapporo Medical University, School of Medicine, S-1, W-16, Chuo-ku, Sapporo 060-8543, Japan.
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