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Sinyuk M, Mulkearns-Hubert EE, Reizes O, Lathia J. Cancer Connectors: Connexins, Gap Junctions, and Communication. Front Oncol 2018; 8:646. [PMID: 30622930 PMCID: PMC6308394 DOI: 10.3389/fonc.2018.00646] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Accepted: 12/10/2018] [Indexed: 12/21/2022] Open
Abstract
Despite concerted clinical and research efforts, cancer is a leading cause of death worldwide. Surgery, radiation, and chemotherapy have remained the most common standard-of-care strategies against cancer for decades. However, the side effects of these therapies demonstrate the need to investigate adjuvant novel treatment modalities that minimize the harm caused to healthy cells and tissues. Normal and cancerous cells require communication amongst themselves and with their surroundings to proliferate and drive tumor growth. It is vital to understand how intercellular and external communication impacts tumor cell malignancy. To survive and grow, tumor cells, and their normal counterparts utilize cell junction molecules including gap junctions (GJs), tight junctions, and adherens junctions to provide contact points between neighboring cells and the extracellular matrix. GJs are specialized structures composed of a family of connexin proteins that allow the free diffusion of small molecules and ions directly from the cytoplasm of adjacent cells, without encountering the extracellular milieu, which enables rapid, and coordinated cellular responses to internal and external stimuli. Importantly, connexins perform three main cellular functions. They enable direct gap junction intercellular communication (GJIC) between cells, form hemichannels to allow cell communication with the extracellular environment, and serve as a site for protein-protein interactions to regulate signaling pathways. Connexins themselves have been found to promote tumor cell growth and invasiveness, contributing to the overall tumorigenicity and have emerged as attractive anti-tumor targets due to their functional diversity. However, connexins can also serve as tumor suppressors, and therefore, a complete understanding of the roles of the connexins and GJs in physiological and pathophysiological conditions is needed before connexin targeting strategies are applied. Here, we discuss how the three aspects of connexin function, namely GJIC, hemichannel formation, and connexin-protein interactions, function in normal cells, and contribute to tumor cell growth, proliferation, and death. Finally, we discuss the current state of anti-connexin therapies and speculate which role may be most amenable for the development of targeting strategies.
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Affiliation(s)
- Maksim Sinyuk
- Department of Biological, Geological, and Environmental Sciences, Cleveland State University, Cleveland, OH, United States
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Erin E. Mulkearns-Hubert
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Ofer Reizes
- Department of Biological, Geological, and Environmental Sciences, Cleveland State University, Cleveland, OH, United States
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
- Cleveland Clinic Lerner College of Medicine, Cleveland Clinic, Cleveland, OH, United States
- Case Comprehensive Cancer Center, Case Western University, Cleveland, OH, United States
| | - Justin Lathia
- Department of Biological, Geological, and Environmental Sciences, Cleveland State University, Cleveland, OH, United States
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
- Cleveland Clinic Lerner College of Medicine, Cleveland Clinic, Cleveland, OH, United States
- Case Comprehensive Cancer Center, Case Western University, Cleveland, OH, United States
- Rose Ella Burkhardt Brain Tumor and Neuro-Oncology Center, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
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Çelebi B, Elçin YM. Proteome Analysis of Rat Bone Marrow Mesenchymal Stem Cell Subcultures. J Proteome Res 2009; 8:2164-72. [DOI: 10.1021/pr800590g] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Betül Çelebi
- Ankara University, Faculty of Science and Biotechnology Institute, AU-TEBNL, Tissue Engineering, Biomaterials and Nanobiotechnology Laboratory, Ankara, Turkey
| | - Y. Murat Elçin
- Ankara University, Faculty of Science and Biotechnology Institute, AU-TEBNL, Tissue Engineering, Biomaterials and Nanobiotechnology Laboratory, Ankara, Turkey
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Frank DK, Szymkowiak B, Hughes CA. Connexin expression and gap junctional intercellular communication in human squamous cell carcinoma of the head and neck. Otolaryngol Head Neck Surg 2006; 135:736-43. [PMID: 17071304 DOI: 10.1016/j.otohns.2006.06.1242] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Accepted: 06/06/2006] [Indexed: 10/24/2022]
Abstract
OBJECTIVE Our laboratory is investigating the role that gap junction intercellular channels (composed of proteins called connexins) play in communicating apoptotic signals from therapeutically targeted squamous cell carcinoma of the head and neck (SCCHN) cells to adjacent, untreated, "bystander" cells (bystander effect). The nature of this research underscores the importance of delineating connexin expression patterns in SCCHN, and how this correlates with gap junctional intercellular communication (GJIC) and bystander effects. STUDY DESIGN The GJIC activity of a diverse panel of SCCHN cell lines, as well as normal oral epithelial (NOE) cell controls was determined in vitro. These data were correlated with connexin expression patterns determined through connexin 43 and connexin 26 immunofluorescence. RESULTS Cell lines with retained GJIC activity all expressed connexin 43 on the cell membrane. Cell lines that did not communicate microinjected lucifer yellow (lost GJIC activity) showed no connexin expression, either at the cell membrane or in the cytosol. Connexin 26 was not expressed in any of our SCCHN cell lines, whereas both connexin 43 and connexin 26 were expressed in the NOE cell controls. Furthermore, connexin 43 introduction into a GJIC (and connexin) deficient SCCHN cell line conferred no growth inhibitory effect. CONCLUSION Connexin 43 expression correlates with retained GJIC in SCCHN in vitro. Connexin 26 may have a role as a tumor suppressor in SCCHN. SIGNIFICANCE The data presented have relevance to our ongoing investigations of gap-junction mediated bystander effects in SCCHN and are being expanded to investigations on actual SCCHN tumor specimens.
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Affiliation(s)
- Douglas K Frank
- Department of Otolaryngology-Head and Neck Surgery and the Head and Neck Cancer Molecular Biology Research Laboratory, Division of Basic Sciences, New York, New York, USA.
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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: 13.3] [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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