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Hosseindoost S, Dehpour AR, Dehghan S, Javadi SAH, Arjmand B, Fallah A, Hadjighassem M. Fluoxetine enhances the antitumor effect of olfactory ensheathing cell-thymidine kinase/ganciclovir gene therapy in human glioblastoma multiforme cells through upregulation of Connexin43 levels. Drug Dev Res 2023; 84:1739-1750. [PMID: 37769152 DOI: 10.1002/ddr.22119] [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: 05/03/2023] [Revised: 08/30/2023] [Accepted: 09/11/2023] [Indexed: 09/30/2023]
Abstract
Glioblastoma multiforme (GBM) is the most invasive form of primary brain astrocytoma, resulting in poor clinical outcomes. Herpes simplex virus thymidine kinase/ganciclovir (HSV-TK/GCV) gene therapy is considered a promising strategy for GBM treatment. Since Connexin43 (Cx43) expression is reduced in GBM cells, increasing Cx43 levels could enhance the effectiveness of gene therapy. The present study aims to examine the impact of fluoxetine on HSV-TK/GCV gene therapy in human GBM cells using human olfactory ensheathing cells (OECs) as vectors. The effect of fluoxetine on Cx43 levels was assessed using the western blot technique. GBM-derived astrocytes and OECs-TK were Cocultured, and the effect of fluoxetine on the Antitumor effect of OEC-TK/GCV gene therapy was evaluated using MTT assay and flow cytometry. Our results showed that fluoxetine increased Cx43 levels in OECs and GBM cells and augmented the killing effect of OECs-TK on GBM cells. Western blot data revealed that fluoxetine enhanced the Bax/Bcl2 ratio and the levels of cleaved caspase-3 in the coculture of OECs-TK and GBM cells. Moreover, flow cytometry data indicated that fluoxetine increased the percentage of apoptotic cells in the coculture system. This study suggests that fluoxetine, by upregulating Cx43 levels, could strengthen the Antitumor effect of OEC-TK/GCV gene therapy on GBM cells.
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Affiliation(s)
- Saereh Hosseindoost
- Pain Research Center, Neuroscience Institute, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran
- Brain and Spinal Cord Injury Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Ahmad R Dehpour
- Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran
- Department of Pharmacology, Tehran University of Medical Sciences, Tehran, Iran
| | - Samaneh Dehghan
- Stem Cell and Regenerative Medicine Research Center, Iran University of Medical Sciences, Tehran, Iran
- Eye Research Center, The Five Senses Institute, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - Seyed A H Javadi
- Brain and Spinal Cord Injury Research Center, Tehran University of Medical Sciences, Tehran, Iran
- Neurosurgery Department, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran
| | - Babak Arjmand
- Cell Therapy and Regenerative Medicine Research Center, Endocrinology and Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
- Metabolomics and Genomics Research Center, Endocrinology and Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Ali Fallah
- Space Medicine B.V., Rotterdam, the Netherlands
- Systems and Synthetic Biology Group, Mede Bioeconomy Company, Tehran, Iran
| | - Mahmoudreza Hadjighassem
- Brain and Spinal Cord Injury Research Center, Tehran University of Medical Sciences, Tehran, Iran
- Department of Neuroscience and Addiction Studies, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
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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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Gallego C, Jaracz-Ros A, Laganà M, Mercier-Nomé F, Domenichini S, Fumagalli A, Roingeard P, Herfs M, Pidoux G, Bachelerie F, Schlecht-Louf G. Reprogramming of connexin landscape fosters fast gap junction intercellular communication in human papillomavirus-infected epithelia. Front Cell Infect Microbiol 2023; 13:1138232. [PMID: 37260709 PMCID: PMC10228504 DOI: 10.3389/fcimb.2023.1138232] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 04/26/2023] [Indexed: 06/02/2023] Open
Abstract
Human papillomaviruses (HPVs) are highly prevalent commensal viruses that require epithelial stratification to complete their replicative cycle. While HPV infections are most often asymptomatic, certain HPV types can cause lesions, that are usually benign. In rare cases, these infections may progress to non-replicative viral cycles associated with high HPV oncogene expression promoting cell transformation, and eventually cancer when not cleared by host responses. While the consequences of HPV-induced transformation on keratinocytes have been extensively explored, the impact of viral replication on epithelial homeostasis remains largely unexplored. Gap junction intercellular communication (GJIC) is critical for stratified epithelium integrity and function. This process is ensured by a family of proteins named connexins (Cxs), including 8 isoforms that are expressed in stratified squamous epithelia. GJIC was reported to be impaired in HPV-transformed cells, which was attributed to the decreased expression of the Cx43 isoform. However, it remains unknown whether and how HPV replication might impact on the expression of Cx isoforms and GJIC in stratified squamous epithelia. To address this question, we have used 3D-epithelial cell cultures (3D-EpCs), the only model supporting the productive HPV life cycle. We report a transcriptional downregulation of most epithelial Cx isoforms except Cx45 in HPV-replicating epithelia. At the protein level, HPV replication results in a reduction of Cx43 expression while that of Cx45 increases and displays a topological shift toward the cell membrane. To quantify GJIC, we pioneered quantitative gap-fluorescence loss in photobleaching (FLIP) assay in 3D-EpCs, which allowed us to show that the reprogramming of Cx landscape in response to HPV replication translates into accelerated GJIC in living epithelia. Supporting the pathophysiological relevance of our observations, the HPV-associated Cx43 and Cx45 expression pattern was confirmed in human cervical biopsies harboring HPV. In conclusion, the reprogramming of Cx expression and distribution in HPV-replicating epithelia fosters accelerated GJIC, which may participate in epithelial homeostasis and host immunosurveillance.
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Affiliation(s)
- Carmen Gallego
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
| | - Agnieszka Jaracz-Ros
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
| | - Marta Laganà
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
| | - Françoise Mercier-Nomé
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
- US31-UMS3679-Plateforme PHIC, Ingénierie et Plateformes au Service de l’Innovation Thérapeutique (IPSIT), INSERM, CNRS, Université Paris-Saclay, Orsay, France
| | - Séverine Domenichini
- UMS-IPSIT Plateforme MIPSIT, Université Paris-Saclay, CNRS, Inserm, Ingénierie et Plateformes au Service de l’Innovation Thérapeutique, Orsay, France
| | - Amos Fumagalli
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier, France
| | - Philippe Roingeard
- INSERM U1259, Université de Tours et CHRU de Tours & Plateforme IBiSA des Microscopies, PPF ASB, CHRU de Tours, Tours, France
| | - Michael Herfs
- Laboratory of Experimental Pathology, GIGA-Cancer, University of Liège, Liège, Belgium
| | | | - Françoise Bachelerie
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
| | - Géraldine Schlecht-Louf
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
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Faraone I, Sinisgalli C, Ostuni A, Armentano MF, Carmosino M, Milella L, Russo D, Labanca F, Khan H. Astaxanthin anticancer effects are mediated through multiple molecular mechanisms: A systematic review. Pharmacol Res 2020; 155:104689. [PMID: 32057895 DOI: 10.1016/j.phrs.2020.104689] [Citation(s) in RCA: 78] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 02/04/2020] [Accepted: 02/10/2020] [Indexed: 02/07/2023]
Abstract
During the latest decades, the interest on the effectiveness of natural compounds and their impact on human health constantly increased, especially on those demonstrating to be effective on cancer. Molecules coming from nature are currently used in chemotherapy like Taxol, Vincristine or Vinblastine, and several other natural substances have been showed to be active in reducing cancer cell progression and migration. Among them, astaxanthin, a xanthophyll red colored carotenoid, displayed different biological activities including, antinflammatory, antioxidant, proapoptotic, and anticancer effects. It can induce apoptosis through downregulation of antiapoptotic protein (Bcl-2, p-Bad, and survivin) expression and upregulation of proapoptotic ones (Bax/Bad and PARP). Thanks to these mechanisms, it can exert anticancer effects towards colorectal cancer, melanoma, or gastric carcinoma cell lines. Moreover, it possesses antiproliferative activity in many experimental models and enhances the effectiveness of conventional chemotherapic drugs on tumor cells underling its potential future use. This review provides an overview of the current knowledge on the anticancer potential of astaxanthin by modulating several molecular targets. While it has been clearly demonstrated its multitarget activity in the prevention and regression of malignant cells in in vitro or in preclinical investigations, further clinical studies are needed to assess its real potential as anticancer in humans.
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Affiliation(s)
- Immacolata Faraone
- Dipartimento di Scienze, Università della Basilicata, Via dell'Ateneo Lucano, 10 85100 Potenza, Italy; BioActiPlant s.r.l., Via dell'Ateneo lucano, 10 85100, Potenza, Italy
| | - Chiara Sinisgalli
- Dipartimento di Scienze, Università della Basilicata, Via dell'Ateneo Lucano, 10 85100 Potenza, Italy; BioActiPlant s.r.l., Via dell'Ateneo lucano, 10 85100, Potenza, Italy
| | - Angela Ostuni
- Dipartimento di Scienze, Università della Basilicata, Via dell'Ateneo Lucano, 10 85100 Potenza, Italy; BioActiPlant s.r.l., Via dell'Ateneo lucano, 10 85100, Potenza, Italy
| | - Maria Francesca Armentano
- Dipartimento di Scienze, Università della Basilicata, Via dell'Ateneo Lucano, 10 85100 Potenza, Italy; BioActiPlant s.r.l., Via dell'Ateneo lucano, 10 85100, Potenza, Italy
| | - Monica Carmosino
- Dipartimento di Scienze, Università della Basilicata, Via dell'Ateneo Lucano, 10 85100 Potenza, Italy; BioActiPlant s.r.l., Via dell'Ateneo lucano, 10 85100, Potenza, Italy
| | - Luigi Milella
- Dipartimento di Scienze, Università della Basilicata, Via dell'Ateneo Lucano, 10 85100 Potenza, Italy.
| | - Daniela Russo
- Dipartimento di Scienze, Università della Basilicata, Via dell'Ateneo Lucano, 10 85100 Potenza, Italy; BioActiPlant s.r.l., Via dell'Ateneo lucano, 10 85100, Potenza, Italy
| | - Fabiana Labanca
- Dipartimento di Scienze, Università della Basilicata, Via dell'Ateneo Lucano, 10 85100 Potenza, Italy.
| | - Haroon Khan
- Department of Pharmacy, Abdul Wali Khan University, Mardan, 23200, Pakistan
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Astaxanthin as a Peroxisome Proliferator-Activated Receptor (PPAR) Modulator: Its Therapeutic Implications. Mar Drugs 2019; 17:md17040242. [PMID: 31018521 PMCID: PMC6521084 DOI: 10.3390/md17040242] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 04/19/2019] [Accepted: 04/19/2019] [Indexed: 12/14/2022] Open
Abstract
Peroxisome proliferator-activated receptors (PPARs) are part of the nuclear hormone receptors superfamily that plays a pivotal role in functions such as glucose and lipid homeostasis. Astaxanthin (ASX) is a lipid-soluble xanthophyll carotenoid synthesized by many microorganisms and various types of marine life that is known to possess antioxidant, anti-inflammatory, antidiabetic, anti-atherosclerotic, and anticancer activities. As such, it is a promising nutraceutical resource. ASX-mediated modulation of PPARs and its therapeutic implications in various pathophysiological conditions are described in this review. ASX primarily enhances the action of PPARα and suppresses that of PPARβ/δ and PPARγ, but it has also been confirmed that ASX displays the opposite effects on PPARs, depending on the cell context. Anti-inflammatory effects of ASX are mediated by PPARγ activation, which induces the expression of pro-inflammatory cytokines in macrophages and gastric epithelial cells. The PPARγ-agonistic effect of ASX treatment results in the inhibition of cellular growth and apoptosis in tumor cells. Simultaneous and differential regulation of PPARα and PPARγ activity by ASX has demonstrated a hepatoprotective effect, maintaining hepatic lipid homeostasis and preventing related hepatic problems. Considering additional therapeutic benefits of ASX such as anti-gastric, cardioprotective, immuno-modulatory, neuroprotective, retinoprotective, and osteogenic effects, more studies on the association between ASX-mediated PPAR regulation and its therapeutic outcomes in various pathophysiological conditions are needed to further elucidate the role of ASX as a novel nutraceutical PPAR modulator.
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Connexins and Pannexins: Important Players in Tumorigenesis, Metastasis and Potential Therapeutics. Int J Mol Sci 2018; 19:ijms19061645. [PMID: 29865195 PMCID: PMC6032133 DOI: 10.3390/ijms19061645] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Revised: 05/25/2018] [Accepted: 05/28/2018] [Indexed: 12/15/2022] Open
Abstract
Since their characterization more than five decades ago, gap junctions and their structural proteins-the connexins-have been associated with cancer cell growth. During that period, the accumulation of data and molecular knowledge about this association revealed an apparent contradictory relationship between them and cancer. It appeared that if gap junctions or connexins can down regulate cancer cell growth they can be also implied in the migration, invasion and metastatic dissemination of cancer cells. Interestingly, in all these situations, connexins seem to be involved through various mechanisms in which they can act either as gap-junctional intercellular communication mediators, modulators of signalling pathways through their interactome, or as hemichannels, which mediate autocrine/paracrine communication. This complex involvement of connexins in cancer progression is even more complicated by the fact that their hemichannel function may overlap with other gap junction-related proteins, the pannexins. Despite this complexity, the possible involvements of connexins and pannexins in cancer progression and the elucidation of the mechanisms they control may lead to use them as new targets to control cancer progression. In this review, the involvements of connexins and pannexins in these different topics (cancer cell growth, invasion/metastasis process, possible cancer therapeutic targets) are discussed.
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Abstract
Communication among cells via direct cell-cell contact by connexin gap junctions, or between cell and extracellular environment via pannexin channels or connexin hemichannels, is a key factor in cell function and tissue homeostasis. Upon malignant transformation in different cancer types, the dysregulation of these connexin and pannexin channels and their effect in cellular communication, can either enhance or suppress tumorigenesis and metastasis. In this review, we will highlight the latest reports on the role of the well characterized connexin family and its ability to form gap junctions and hemichannels in cancer. We will also introduce the more recently discovered family of pannexin channels and our current knowledge about their involvement in cancer progression.
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Affiliation(s)
- Jean X Jiang
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX, 78229, USA
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, N6A5C1, Canada.
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Sun P, Dong L, MacDonald AI, Akbari S, Edward M, Hodgins MB, Johnstone SR, Graham SV. HPV16 E6 Controls the Gap Junction Protein Cx43 in Cervical Tumour Cells. Viruses 2015; 7:5243-56. [PMID: 26445057 PMCID: PMC4632379 DOI: 10.3390/v7102871] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 09/24/2015] [Accepted: 09/30/2015] [Indexed: 12/16/2022] Open
Abstract
Human papillomavirus type 16 (HPV16) causes a range of cancers including cervical and head and neck cancers. HPV E6 oncoprotein binds the cell polarity regulator hDlg (human homologue of Drosophila Discs Large). Previously we showed in vitro, and now in vivo, that hDlg also binds Connexin 43 (Cx43), a major component of gap junctions that mediate intercellular transfer of small molecules. In HPV16-positive non-tumour cervical epithelial cells (W12G) Cx43 localised to the plasma membrane, while in W12T tumour cells derived from these, it relocated with hDlg into the cytoplasm. We now provide evidence that E6 regulates this cytoplasmic pool of Cx43. E6 siRNA depletion in W12T cells resulted in restoration of Cx43 and hDlg trafficking to the cell membrane. In C33a HPV-negative cervical tumour cells expressing HPV16 or 18 E6, Cx43 was located primarily in the cytoplasm, but mutation of the 18E6 C-terminal hDlg binding motif resulted in redistribution of Cx43 to the membrane. The data indicate for the first time that increased cytoplasmic E6 levels associated with malignant progression alter Cx43 trafficking and recycling to the membrane and the E6/hDlg interaction may be involved. This suggests a novel E6-associated mechanism for changes in Cx43 trafficking in cervical tumour cells.
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Affiliation(s)
- Peng Sun
- Feinberg School of Medicine, North Western University, Chicago, IL 60611, USA.
| | - Li Dong
- MRC-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, Scotland, UK.
| | - Alasdair I MacDonald
- MRC-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, Scotland, UK.
| | - Shahrzad Akbari
- MRC-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, Scotland, UK.
| | - Michael Edward
- Dermatology, School of Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TT, Scotland, UK.
| | - Malcolm B Hodgins
- Dermatology, School of Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TT, Scotland, UK.
| | - Scott R Johnstone
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TT, Scotland, UK.
| | - Sheila V Graham
- MRC-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, Scotland, UK.
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Levonorgestrel Inhibits Human Endometrial Cell Proliferation through the Upregulation of Gap Junctional Intercellular Communication via the Nuclear Translocation of Ser255 Phosphorylated Cx43. BIOMED RESEARCH INTERNATIONAL 2015; 2015:758684. [PMID: 26161412 PMCID: PMC4486311 DOI: 10.1155/2015/758684] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Revised: 09/27/2014] [Accepted: 09/28/2014] [Indexed: 11/17/2022]
Abstract
Objects. To assess whether LNG exerts antiproliferation effects on human endometrial cells through changes of GJIC function and the phosphorylated Cx43. Methods. Cell proliferation and apoptosis of human endometrial stromal cells (HESCs) and glandular cells (HEGCs) treated with LNG in a dose- and time-dependent manner. GJIC change and further total Cx43 and serine 368 and 255 phosphorylated Cx43 were measured. Results. 5 × 10−5 mol/L LNG revealed a time-dependent inhibition of cell proliferation and an increase of apoptosis in both HESCs and HEGCs. Furthermore, these cells demonstrated a significant GJIC enhancement upon treatment with 5 × 10−5 mol/L for 48 hours. The effects of LNG were most noticeable in HESCs rather than in HEGCs. Associated with these changes, LNG induced a relative increase in total Cx43 in a time-dependent manner but not Ser368 phosphorylated Cx43. Moreover, laser scanning confocal microscope confirmed the increased expression of total Cx43 in the cytoplasm and, interestingly, the nuclear translocation of Ser255 phosphorylated Cx43. Conclusions. LNG likely inhibits the proliferation and promotes apoptosis in HESCs and HEGCs though an increase in gap junction permeability in vitro, which is achieved through the upregulation of Cx43 expression and the translocation of serine 255 phosphorylated Cx43 from the plasma to the nuclear compartment.
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Abstract
SUMMARY Melanoma cells interact with and depend on seemingly normal cells in their tumour microenvironment to allow the acquisition of the hallmarks of solid cancer. In general, there are three types of interaction of melanoma cells with their microenvironment. First, there is bilateral communication between melanoma cells and the stroma, which includes fibroblasts, endothelial cells, immune cells, soluble molecules, and the extracellular matrix. Second, while under normal conditions keratinocytes control localisation and proliferative behaviour of melanocytes in the epidermis, once this balance is disturbed and a melanoma has developed, melanoma cells may take over the control of their epidermal tumour microenvironment. Finally, there are subcompartments within tumours with different microenvironmental milieu defined by their access to oxygen and nutrients. Therefore, different melanoma cells within a tumour face different microenvironments. Interactions between melanoma cells among each other and with the cell types in their microenvironment happen through endocrine and paracrine communication and/or through direct contact via cell-cell and cell-matrix adhesion, and gap junctional intercellular communication (GJIC). Connexins have been identified as key molecules for direct cell-cell communication and are also thought to be important for the release of signalling molecules from cells to the microenvironment. In this review we provide an update of the alterations in cell-cell communication in melanoma and the tumour microenvironment associated with melanoma development and progression.
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Abstract
Human papillomavirus (HPV) infection is clinically very common. It is usually a major risk factor in the development of cutaneous benign lesions, cervical cancer and a variety of other malignancies. The biological function of ubiquitination as an intracellular proteasomal-mediated form of protein degradation and an important modulator in the regulation of many fundamental cellular processes has been increasingly recognized over the last decade. HPV proteins have been demonstrated to evolve different strategies to utilize the ubiquitin system for their own purposes. The putative roles of E3 ubiquitin ligases in HPV-induced carcinogenesis have become increasingly apparent, although the mechanisms remain unclear. In this review we provide an update on the mechanisms of the involvement of E3 ubiquitin ligases in HPV-induced carcinogenesis, focusing on their interaction with HPV proteins and their roles in several signalling pathways. Targeting the E3 ubiquitin ligases might offer potential therapeutic strategies for HPV-related diseases in future.
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Affiliation(s)
- Zhifeng Lou
- Department of Dentistry, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, People's Republic of China
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Khan Z, Yaiw KC, Wilhelmi V, Lam H, Rahbar A, Stragliotto G, Söderberg-Nauclér C. Human cytomegalovirus immediate early proteins promote degradation of connexin 43 and disrupt gap junction communication: implications for a role in gliomagenesis. Carcinogenesis 2013; 35:145-54. [PMID: 23978378 DOI: 10.1093/carcin/bgt292] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
A lack of gap junctional intercellular communication (GJIC) is common in cancer. Many oncogenic viruses have been shown to downregulate the junctional protein connexin 43 (Cx43) and reduce GJIC. Human cytomegalovirus (HCMV) is a ubiquitous, species-specific betaherpesvirus that establishes life-long latency after primary infection. It encodes two viral gene products, immediate early (IE) proteins IE1 and IE2, which are crucial in viral replication and pathogenesis of many diseases. Emerging evidence demonstrates that HCMV DNA and proteins are highly prevalent in glioblastoma multiforme (GBM) and in other tumors, but HCMV's role in tumorigenesis remains obscure. In the present study, we examined the effects of HCMV infection on Cx43 expression and GJIC as well as the viral mechanism mediating the effects in human GBM cells and tissue samples. We found that HCMV downregulated Cx43 protein, resulting in disruption of functional GJIC as assayed by fluorescent dye transfer assay. We show that both HCMV-IE72 and IE86 mediate downregulation of Cx43 by silencing RNA targeting either IE72 or IE86 coupled with ganciclovir. This finding was further validated by transfection with expression vectors encoding IE72 or IE86, and we show that viral-mediated Cx43 depletion involved proteasomal degradation. Importantly, we also observed that the Cx43 protein levels and IE staining correlated inversely in 10 human GBM tissue specimens. Thus, HCMV regulates Cx43 expression and GJIC, which may contribute to gliomagenesis.
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Affiliation(s)
- Zahidul Khan
- Department of Medicine, Solna, Unit for Experimental Cardiovascular Research, Center for Molecular Medicine, Karolinska Institutet, Stockholm SE-171 76, Sweden and
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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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A functional interaction between the MAGUK protein hDlg and the gap junction protein connexin 43 in cervical tumour cells. Biochem J 2012; 446:9-21. [PMID: 22657348 DOI: 10.1042/bj20111144] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Gap junctions, composed of Cxs (connexins), allow direct intercellular communication. Gap junctions are often lost during the development of malignancy, although the processes behind this are not fully understood. Cx43 is a widely expressed Cx with a long cytoplasmic C-terminal tail that contains several potential protein-interaction domains. Previously, in a model of cervical carcinogenesis, we showed that the loss of gap junctional communication correlated with relocalization of Cx43 to the cytoplasm late in tumorigenesis. In the present study, we demonstrate a similar pattern of altered expression for the hDlg (human discs large) MAGUK (membrane-associated guanylate kinase) family tumour suppressor protein in cervical tumour cells, with partial co-localization of Cx43 and hDlg in an endosomal/lysosomal compartment. Relocalization of these proteins is not due to a general disruption of cell membrane integrity or Cx targeting. Cx43 (via its C-terminus) and hDlg interact directly in vitro and can form a complex in cells. This novel interaction requires the N- and C-termini of hDlg. hDlg is not required for Cx43 internalization in W12GPXY cells. Instead, hDlg appears to have a role in maintaining a cytoplasmic pool of Cx43. These results demonstrate that hDlg is a physiologically relevant regulator of Cx43 in transformed epithelial cells.
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Opposing roles of connexin43 in glioma progression. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2058-67. [DOI: 10.1016/j.bbamem.2011.10.022] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 10/17/2011] [Accepted: 10/24/2011] [Indexed: 12/12/2022]
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Changes in connexin43 expression and localization during pancreatic cancer progression. J Membr Biol 2012; 245:255-62. [PMID: 22729649 DOI: 10.1007/s00232-012-9446-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Accepted: 06/01/2012] [Indexed: 12/11/2022]
Abstract
Gap junctions and gap junction communication have long been recognized to play roles in tissue organization and remodeling through both cell autonomous and intercellular means. We hypothesized that these processes become dysregulated during pancreas cancer progression. Molecular and histological characterization of the gap junction protein, connexin43, during progression of pancreatic ductal adenocarcinoma could yield insight into how these events may contribute to or be modulated during carcinogenesis. In a mouse model of pancreatic ductal adenocarcinoma generated through targeted endogenous expression of Kras(G12D) in the murine pancreas, we examined the evolving expression and localization of connexin43. Overall, connexin43 expression increased over time, and its localization became more widespread. At early stages, connexin43 is found almost exclusively in association with the basolateral membrane of duct cells found in invasive lesions. Connexin43 became increasingly associated with the surrounding stroma over time. Connexin43 phosphorylation was also altered during tumorigenesis, as assessed by migrational changes of the protein in immunoblots. These data suggest a potential role for gap junctions and connexin43 in mediating interactions between and amongst the stromal and epithelial cells in pancreatic ductal adenocarcinoma.
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Expression of gap junction protein connexin 43 in bovine urinary bladder tumours. J Comp Pathol 2011; 144:86-90. [PMID: 20643416 DOI: 10.1016/j.jcpa.2010.05.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Revised: 04/09/2010] [Accepted: 05/26/2010] [Indexed: 11/24/2022]
Abstract
The aetiopathogenesis of urinary bladder tumours in cattle involves prolonged ingestion of bracken fern and infection by bovine papillomavirus types 1 or 2 (BPV-1/2). The oncogenic activity of BPV is largely associated with the major oncoprotein E5. Gap junctions are the only communicating junctions found in animal tissues and are composed of proteins known as connexins. Alterations in connexin expression have been associated with oncogenesis. The present study investigated biochemically and immunohistochemically the expression of connexin 43 in samples of normal (n=2), dysplastic (n=3) and neoplastic (n=23) bovine urothelium. The tumours included 10 carcinomas in situ, five papillary urothelial carcinomas and eight invasive urothelial carcinomas. Normal and dysplastic urothelium had membrane expression of connexin 43, but this was reduced in samples of carcinoma in situ. Papillary urothelial carcinomas showed moderate cytoplasmic and membrane labelling, while invasive carcinoma showed loss of connexin 43 expression.
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Caltabiano R, Torrisi A, Condorelli D, Albanese V, Lanzafame S. High levels of connexin 43 mRNA in high grade astrocytomas. Study of 32 cases with in situ hybridization. Acta Histochem 2010; 112:529-35. [PMID: 19604543 DOI: 10.1016/j.acthis.2009.05.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Revised: 05/06/2009] [Accepted: 05/19/2009] [Indexed: 11/29/2022]
Abstract
Gap junctions are composed of a family of evolutionarily conserved integral plasma membrane proteins termed connexins. The aims of the research reported here were (1) to evaluate the Cx43 protein and mRNA of both low histological grade and high histological grade astrocyte tumors; (2) to evaluate if the immunohistochemistry of the Cx43 protein in astrocytomas could be correlated to histological grade, to proliferative activity (Ki67/Mib1-index) and to immunolabelling of the epidermal growth factor receptor (EGFR); (3) to evaluate if the reduction in levels of the Cx43 protein correlates with reduction in levels of the Cx43 mRNA. This study showed that the immunohistochemical labelling of Cx43 is reduced in grade III and grade IV. Decreased gap junction-mediated intercellular communication corresponds to decreased Cx43 and increased cellular proliferation rates, as measured by immunolabelling of the Ki67 nuclear antigen. This study demonstrated also the persistence in high grade astrocytomas of elevated levels of Cx43 mRNA. The reduced levels of Cx43 protein should not to be ascribed to a reduced genetic transcription, but to an alteration of the post-transcriptional mechanisms such as the regulation of its synthesis and/or the intracellular transport to membrane sites.
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Affiliation(s)
- Rosario Caltabiano
- Department G.F. Ingrassia, Section of Anatomic Pathology, University of Catania, 95123 Catania, Italy
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Yu Y, Yao K. Non-thermal cellular effects of lowpower microwave radiation on the lens and lens epithelial cells. J Int Med Res 2010; 38:729-36. [PMID: 20819410 DOI: 10.1177/147323001003800301] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Because of the increased use of modern radiofrequency devices, public concern about the possible health effects of exposure to microwave radiation has arisen in many countries. It is well established that high-power microwave radiation can induce cataracts via its thermal effects. It remains unclear whether low-power microwave radiation, especially at levels below the current exposure limits, is cataractogenic. This review summarizes studies on the biological effects of low-power microwave radiation on lens and lens epithelial cells (LECs). It has been reported that exposure affects lens transparency, alters cell proliferation and apoptosis, inhibits gap junctional intercellular communication, and induces genetic instability and stress responses in LECs. These results raise the question of whether the ambient microwave environment can induce non-thermal effects in the lens and whether such effects have potential health consequences. Further in vivo studies on the effects on the lens of exposure to low-power microwave radiation are needed.
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Affiliation(s)
- Y Yu
- Eye Centre, Affiliated Second Hospital, College of Medicine, Zhejiang University, Hangzhou, China
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PI3K/Akt signaling is involved in the disruption of gap junctional communication caused by v-Src and TNF-α. Biochem Biophys Res Commun 2010; 400:230-5. [DOI: 10.1016/j.bbrc.2010.08.045] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Accepted: 08/13/2010] [Indexed: 01/29/2023]
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Behrens J, Kameritsch P, Wallner S, Pohl U, Pogoda K. The carboxyl tail of Cx43 augments p38 mediated cell migration in a gap junction-independent manner. Eur J Cell Biol 2010; 89:828-38. [PMID: 20727616 DOI: 10.1016/j.ejcb.2010.06.003] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 06/14/2010] [Accepted: 06/23/2010] [Indexed: 11/28/2022] Open
Abstract
The expression of connexin 43 (Cx43) has been shown to correlate with an enhanced migration of several cell types such as glioma or neural crest cells, but the mechanism remains unclear. We studied whether Cx43 also affects migration in non-neural cells and whether or not this is related to gap junction formation. Therefore, we analysed the migratory activity of HeLa cells under conditions of controlled connexin (Cx) expression. The expression of Cx43 enhanced their migration significantly as compared to Cx deficient wild-type cells. Expression of only the carboxyl tail of Cx43 (Cx43CT, AA 257-382) without channel forming capacity enhanced migration similarly as the full length protein. In contrast, the expression of the N-terminal part of Cx43 (Cx43NT, AA 1-257), which partially retained the gap junction channel function of Cx43, did not increase migration. The enhanced cell migration of HeLa cells expressing either full length Cx43 or the Cx43CT was associated with an increased activation of the p38 MAP kinase. The additional incubation with a specific inhibitor of p38 activation diminished the migration of HeLa-Cx43 cells to levels of control transfected cells. As a proof of concept, we studied whether Cx43 also modulates the migration of endothelial progenitor cells (EPC) which play an important role in angiogenesis. In these cells, which expressed Cx43 as the only connexin, the downregulation of Cx43 by siRNA resulted in a significantly decreased migration. These results demonstrate that expression of Cx43 augments migration via modulation of p38 MAP kinase activity. The carboxyl tail of Cx43 plays an essential role in this signalling pathway which is independent of gap junction function.
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Affiliation(s)
- Juliane Behrens
- Walter Brendel Centre of Experimental Medicine, Ludwig-Maximilians-Universität München, Marchioninistr. 27, D-81377 Munich, Germany
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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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Muggia FM, Peters GJ, Landolph JR. XIII International Charles Heidelberger Symposium and 50 Years of Fluoropyrimidines in Cancer Therapy Held on september 6 to 8, 2007 at New York University Cancer Institute, Smilow Conference Center. Mol Cancer Ther 2009; 8:992-9. [PMID: 19417150 DOI: 10.1158/1535-7163.mct-08-0731] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This conference opened with Franco Muggia, host and principal organizer, thanking Joseph Landolph, co-Chair of the International Scientific Organizing Committee and its members (Franco Muggia, co-Chair, Max Costa, Steven Burakoff, Howard Hochster, Eliezer Huberman, John Bertram, Peter Danenberg, and Richard Moran); the members of the Local Organizing Committee (Drs. Costa, Guttenplan, Geacintov, and Hochster); and the Charles and Patricia Heidelberger Foundation for Cancer Research for developing the scientific program and for working to help him create this special symposium honoring the late Charles Heidelberger, former president of the American Association for Cancer Research, member of the National Academy of Sciences, and extraordinary scientist in the fields of carcinogenesis and cancer chemotherapy. It was most appropriate to commemorate the 50th anniversary of the patent obtained by him for 5-fluorouracil (5FU), a drug that came to symbolize the promise chemotherapy of nonhematologic malignancies. After this compound was shown to be helpful in the treatment of colorectal and breast cancers, Dr. Heidelberger proceeded to develop other fluoropyrimidines and to inspire Ph.D. students and postdoctoral fellows to investigate their mechanisms of action and to develop assays applicable to clinical specimens (what we now refer to as translational science). Steven Burakoff, director of the NYU Cancer Institute (2000 to 2008), followed with welcoming remarks. Dr. Burakoff pointed to his personal fortuitous connection to the Symposium: The famous immunologist, Michael Heidelberger, Charles' father, who was known as the Father of Immunochemistry, trained Elvin Kabat while at Columbia, who trained Baruch Benacerraf, who moved from NYU to Harvard and subsequently became Burakoff's mentor. The renowned NYU Division of Immunology carries the name Michael Heidelberger because he spent more than 30 years in the Department of Pathology at the NYU School of Medicine after retiring from Columbia University.
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Affiliation(s)
- Franco M Muggia
- New York University Cancer Institute, NYU Langone Medical Center, New York, New York 10016, USA.
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Peterson-Roth E, Brdlik CM, Glazer PM. Src-Induced cisplatin resistance mediated by cell-to-cell communication. Cancer Res 2009; 69:3619-24. [PMID: 19351863 DOI: 10.1158/0008-5472.can-08-0985] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cisplatin-induced cell death can be triggered by cell-to-cell communication through gap junctions. Here, we show that activated src produces tyrosine phosphorylation of the gap junction protein connexin 43, decreases gap junction communication, and increases cell survival in response to cisplatin. Experiments with mixed cell populations show that src activity in one cell can confer increased cisplatin survival on neighboring cells, even when the neighboring cells lack such src activity. This work is the first demonstration that expression of an oncogene in one cell can affect the survival of a neighboring cell not expressing the oncogene in response to a chemotherapeutic drug. The trans-acting effect of activated src on neighboring cells can be blocked by inhibitors of src kinase or by siRNA-mediated knockdown of src expression, and it can be counteracted by forced up-regulation of connexin 43, via either gene transfer or proteasome inhibition. These results identify a novel pathway of cisplatin resistance that may be amenable to therapeutic intervention.
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Affiliation(s)
- Elizabeth Peterson-Roth
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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Dbouk HA, Mroue RM, El-Sabban ME, Talhouk RS. Connexins: a myriad of functions extending beyond assembly of gap junction channels. Cell Commun Signal 2009; 7:4. [PMID: 19284610 PMCID: PMC2660342 DOI: 10.1186/1478-811x-7-4] [Citation(s) in RCA: 183] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Accepted: 03/12/2009] [Indexed: 01/03/2023] Open
Abstract
Connexins constitute a large family of trans-membrane proteins that allow intercellular communication and the transfer of ions and small signaling molecules between cells. Recent studies have revealed complex translational and post-translational mechanisms that regulate connexin synthesis, maturation, membrane transport and degradation that in turn modulate gap junction intercellular communication. With the growing myriad of connexin interacting proteins, including cytoskeletal elements, junctional proteins, and enzymes, gap junctions are now perceived, not only as channels between neighboring cells, but as signaling complexes that regulate cell function and transformation. Connexins have also been shown to form functional hemichannels and have roles altogether independent of channel functions, where they exert their effects on proliferation and other aspects of life and death of the cell through mostly-undefined mechanisms. This review provides an updated overview of current knowledge of connexins and their interacting proteins, and it describes connexin modulation in disease and tumorigenesis.
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Affiliation(s)
- Hashem A Dbouk
- Department of Biology, Faculty of Arts and Sciences, American University of Beirut, Beirut, Lebanon.
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Abstract
Dietary intake of lycopene is inversely associated with the risk of many cancers. Preclinical studies show that lycopene has potent in vitro and in vivo antitumor effects, suggesting potential preventive and therapeutic roles for the compound. However, clinical trials with lycopene have only recently been started, and available clinical data preclude firm conclusions with regard to its use in cancer prevention and treatment. Further mechanistic studies and randomized controlled clinical intervention trials with lycopene involving cancer patients are warranted.
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Fornelli F, Leone A, Verdesca I, Minervini F, Zacheo G. The influence of lycopene on the proliferation of human breast cell line (MCF-7). Toxicol In Vitro 2007; 21:217-23. [PMID: 17140762 DOI: 10.1016/j.tiv.2006.09.024] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Revised: 09/01/2006] [Accepted: 09/25/2006] [Indexed: 10/24/2022]
Abstract
Lycopene, a non-provitaminic carotenoid, present in many fruit and vegetables, such as tomatoes and their processed products, has been associated with decreased risk of chronic diseases including cancer. The influence of lycopene on the proliferation of the breast tumour cell line (MCF-7) was tested using MTT and BrdU assays at different time intervals (from 24 to 72h) and dose-response (from 0.125 to 100microM). The induction of Gap Junction Intercellular Communication (GJIC) was evaluated by dye-transfer assay using Lucifer Yellow on monolayer cells treated with different lycopene concentrations (from 0.125 to 5microM) for 6 to 48h. The Minimal Inhibitory Concentration (MIC) of lycopene was of 5microM, after a 24h exposure. A prolonged exposure time (72h) induced a similar inhibitory effect. Lycopene stimulated the functionality of GJIC at concentrations of 1microM after 24h and this effect was dose-dependent. The induction of GJIC by lycopene was confirmed by an increased expression of connexin 43. Collectively, the above data confirm the inhibitor effects of lycopene on MCF-7 cell growth and suggest that lycopene is involved in the modulation of the gap junction intercellular communication in this cell line, as observed for other cancer cell lines.
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Affiliation(s)
- F Fornelli
- Institute of Sciences of Food Production, Consiglio Nazionale delle Ricerche, Bari, Italy
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Abbaci M, Barberi-Heyob M, Stines JR, Blondel W, Dumas D, Guillemin F, Didelon J. Gap junctional intercellular communication capacity by gap-FRAP technique: A comparative study. Biotechnol J 2007; 2:50-61. [PMID: 17225250 DOI: 10.1002/biot.200600092] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Gap junctions play an important role in vital functions, including the regulation of cell growth and cell differentiation. Connexins 43 (Cx43) are the most widely expressed gap junction proteins. Cellular localization of phosphorylated Cx43 has been implicated in the capacity of gap junctional intercellular communication (GJIC). To follow the functionality of GJIC of different cell types, in monolayer cultures, characterized by different patterns of phosphorylated Cx43, we used a fluorescence recovery after photobleaching (FRAP) technique, and compared two tracers, 5(6)-carboxyfluorescein diacetate (CFDA) and calcein acetoxymethylester (AM). The GJIC capacity was quantified by estimating fluorescence redistribution parameters. The functionality of GJIC was in relation with the staining localization of phosphorylated Cx43 to the cell-cell contact areas, corresponding to gap junctions between contacting cells. GJIC involvement in fluorescence restitution after photobleaching was checked by a gap junction channel inhibition assay. We demonstrated that the choice of the dye did not significantly influence the fluorescence recovery percentages despite a cell line-dependent CFDA release, whereas it had an important impact on fluorescence kinetic profiles. This study reinforces the interest of the gap-FRAP approach to quantify modifications in the functionality of gap junctions and, above all, argues about the limits of CFDA for 3-D future approaches.
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Affiliation(s)
- Muriel Abbaci
- Faculté de Médecine, Nancy University, Vandoeuvre-les-Nancy, France
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Hernandez M, Shao Q, Yang XJ, Luh SP, Kandouz M, Batist G, Laird DW, Alaoui-Jamali MA. A histone deacetylation-dependent mechanism for transcriptional repression of the gap junction gene cx43 in prostate cancer cells. Prostate 2006; 66:1151-61. [PMID: 16652385 DOI: 10.1002/pros.20451] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND The connexin 43 gene (cx43, GJA1) mediates gap junctional intercellular communication (GJIC), which regulates tissue homeostasis. cx43 is frequently downregulated in prostate cancer. We investigated the role of a histone deacetylase (HDAC)-dependent mechanism in the transcriptional repression of cx43 in a panel of prostate cancer cells. METHODS The impact of Trichostatin A (TSA), an inhibitor of HDAC, on exogenous and endogenous cx43 gene transcription was examined by the luciferase assay, Northern blot, nuclear run-on, Western blot, and chromatin immunoprecipitation assays. RESULTS Trichostatin A induces transcription of cx43 gene and GJIC. The co-activator p300/CBP synergizes with TSA for cx43 promoter activation. We identified a promoter region where cooperation between Ap1 and Sp1 elements was essential for TSA-induced cx43 transcription. TSA increased the level of hyperacetylated histones bound to cx43 promoter. CONCLUSION Our results highlight the potential utility of inhibitors of HDAC to restore cx43 gene expression in prostate cancer.
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Affiliation(s)
- Maite Hernandez
- Departments of Medicine, Oncology, and Pharmacology and Therapeutics, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, McGill University, 3755 Chemin de la Cote Ste-Catherine, Montreal, Quebec, Canada
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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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Yi ZC, Liu YZ, Li HX, Yin Y, Zhuang FY, Fan YB, Wang Z. Tellimagrandin I enhances gap junctional communication and attenuates the tumor phenotype of human cervical carcinoma HeLa cells in vitro. Cancer Lett 2005; 242:77-87. [PMID: 16338066 DOI: 10.1016/j.canlet.2005.10.044] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2005] [Revised: 10/26/2005] [Accepted: 10/26/2005] [Indexed: 10/25/2022]
Abstract
Tellimagrandin I and chebulinic acid, two hydrolysable tannins, have been shown to exert anti-tumor properties. Dysfunctional gap junctional communication (GJIC) has been recognized as being involved in carcinogenesis. The human cervical carcinoma HeLa cells have been reported to be deficient in functional GJIC. In present study, we investigated whether tellimagrandin I and chebulinic acid might restore functional GJIC in HeLa cells. Both compounds could inhibit the growth of HeLa cells. Either Lucifer yellow transfer assay or calcein transfer assay demonstrated that tellimagrandin I improved GJIC in HeLa cells while chebulinic acid showed no effect on GJIC. The GJIC enhancement by tellimagrandin I occurred along with an increase of Cx43 gene expression at mRNA and protein levels. Exposure to tellimagrandin I also led to inhibition of proliferation and anchorage-independent growth of HeLa cells. In addition, tellimagrandin I decreased the percentage of cells in the G0/G1 and G2/M phases coinciding with an increase in the percentage of cells in the S phase. The accumulation of cells in S phase was coupled with a decreased expression of cyclin A that was critical to the progression of S phase. These results suggested that restoring GJIC might be one explanation for tellimagrandin I antitumor effects, whereas chebulinic acid exerted antitumor action through other pathways.
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Affiliation(s)
- Zong-Chun Yi
- Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China.
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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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King TJ, Bertram JS. Connexins as targets for cancer chemoprevention and chemotherapy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2005; 1719:146-60. [PMID: 16263076 DOI: 10.1016/j.bbamem.2005.08.012] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Revised: 08/25/2005] [Accepted: 08/31/2005] [Indexed: 02/02/2023]
Abstract
Cells within a tissue continuously interact to coordinate normal tissue functions and maintain homeostasis. Gap junctional communication (GJC), mediated by the connexin protein family, allows this type of intercellular crosstalk resulting in synchronized and cooperative tissue behavior such as cardiac contraction. In cancer, loss of these types of cell:cell interactions has been shown to facilitate tumorigenesis and enable the autonomous cell behavior associated with transformed cells. Indeed, many human tumor lines demonstrate deficient or aberrant GJC and/or loss of connexin expression. Restoration of exogenous connexin expression/GJC function is correlated with increased cell growth control both in vitro and in vivo. In support of this growth regulatory hypothesis, decreased connexin expression has been observed in situ in early human neoplasia of various organs. Additionally, genetically engineered mice lacking particular connexins (Connexins 32 or 43) exhibit increased susceptibility to radiation and chemically-induced liver and/or lung tumorigenesis. These studies strongly suggest that connexins and GJC serve a tumor suppressor role. Consistent with this proposed role, in a model cell culture system, retinoids and carotenoids up-regulate Connexin43 (Cx43) expression in direct proportion to their ability to suppress carcinogen-induced neoplastic transformation. Here, we discuss the important role of connexins and GJC in tumorigenesis and suggest the possibility of connexins as potential anti-oncogenic targets for chemoprevention and/or chemotherapy.
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36
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Aasen T, Graham SV, Edward M, Hodgins MB. Reduced expression of multiple gap junction proteins is a feature of cervical dysplasia. Mol Cancer 2005; 4:31. [PMID: 16091133 PMCID: PMC1198252 DOI: 10.1186/1476-4598-4-31] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2005] [Accepted: 08/09/2005] [Indexed: 11/24/2022] Open
Abstract
Cervical dysplasia is a premalignant lesion associated with human papillomavirus (HPV) infection which, over time, can turn cancerous. Previous studies have indicated that loss of gap junctions may be a feature of cervical cancer and premalignant dysplasia. Loss of the gap junction protein connexin43 has been demonstrated in dysplastic cervix, but other connexins have not been investigated. In contrast we previously showed that HPV-associated cutaneous warts – and other hyperproliferative skin conditions – display a dramatic upregulation of certain connexins, in particular connexin26. By performing immunofluorescence staining after antigen retrieval of paraffin-embedded cervical tissue samples, this study reports for the first time that connexin26 and connexin30, in addition to connexin43, are expressed in differentiating cells of normal human cervical epithelia. Moreover, in dysplastic ectocervix, all connexins studied display a dramatic loss of expression compared to adjacent normal epithelia. The role of connexins in keratinocyte differentiation and carcinogenesis is discussed.
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Affiliation(s)
- Trond Aasen
- Squamous Cell Biology and Dermatology, Division of Cancer Sciences and Molecular Pathology, Robertson Building, University of Glasgow, 56 Dumbarton Road, Glasgow, G11 6NU, Scotland, UK
- Institute of Biomedical and Life Sciences, Division of Virology, University of Glasgow, Church Street, Glasgow, G11 6JR, Scotland, UK
- Centre for Cutaneous Research, Institute of Cell and Molecular Science, Queen Mary University of London, 4 Newark Street, Whitechapel, London E1 2AT, UK
| | - Sheila V Graham
- Institute of Biomedical and Life Sciences, Division of Virology, University of Glasgow, Church Street, Glasgow, G11 6JR, Scotland, UK
| | - Mike Edward
- Squamous Cell Biology and Dermatology, Division of Cancer Sciences and Molecular Pathology, Robertson Building, University of Glasgow, 56 Dumbarton Road, Glasgow, G11 6NU, Scotland, UK
| | - Malcolm B Hodgins
- Squamous Cell Biology and Dermatology, Division of Cancer Sciences and Molecular Pathology, Robertson Building, University of Glasgow, 56 Dumbarton Road, Glasgow, G11 6NU, Scotland, UK
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Gould VE, Mosquera JM, Leykauf K, Gattuso P, Dürst M, Alonso A. The phosphorylated form of connexin43 is up-regulated in breast hyperplasias and carcinomas and in their neoformed capillaries. Hum Pathol 2005; 36:536-45. [PMID: 15948121 DOI: 10.1016/j.humpath.2005.03.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
We applied an antiserum (SA226P) specifically recognizing the phosphorylated form of connexin43 (P-Cx43) to human breast samples including normal breast samples, with fibrocystic disease (FCD), fibroadenomas (FA), in situ and infiltrating carcinomas of all major types, and miscellaneous extramammary tumors. The findings were compared with those obtained with commercial antisera recognizing all Cx43 forms (pan-Cx43). A subset of samples was stained for Her2-neu and p44/42 to mitogen-activated protein kinase. Paraffin step sections were used. Immunoblots were performed on frozen samples of a representative subset of cases. In the normal breast, FCD, and FA, SA226P stained strongly and extensively most myoepithelial cells (MECs); luminal cells remained unstained. In proliferative FCD and some cellular FA, SA226P stained MEC and the capillary endothelium (CE). In ductal and lobular in situ carcinomas, SA226P reacted strongly and diffusely with the remaining MEC, the CE, and the transformed luminal cells. SA226P stained all infiltrating carcinomas except the tubular variant. In all breast carcinomas, the CE within and adjacent to tumors and some myofibroblasts stained with SA226P. By contrast, pan-Cx43 stained weakly and sporadically the MEC and rare samples of invasive carcinomas. Notably, Mab p44/42 reacted in parallel with the samples stained with SA226P, whereas reactions with Her2 were negative. Immunoblot findings paralleled those obtained immunohistochemically. We conclude that P-Cx43, restricted to MEC in the normal breast, is up-regulated in the same cells in hyperplasias and dysplasias and FA and is strongly up-regulated in invasive carcinomas. Notably, in some proliferative FCD and in most in situ and infiltrating carcinomas, P-Cx43 is strongly expressed in CE within and adjacent to the lesions but not away from them. These findings were paralleled by the strong nuclear reactions noted with Mab p44/42. These phenomena, although not exclusive to malignancy, are particularly conspicuous in breast carcinomas and seemingly reflect active proliferation associated with abnormal gap junctional intercellular communication.
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MESH Headings
- Breast/blood supply
- Breast/metabolism
- Breast/pathology
- Breast Diseases/metabolism
- Breast Diseases/pathology
- Breast Neoplasms/blood supply
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Capillaries/metabolism
- Carcinoma, Ductal, Breast/blood supply
- Carcinoma, Ductal, Breast/metabolism
- Carcinoma, Ductal, Breast/pathology
- Carcinoma, Intraductal, Noninfiltrating/blood supply
- Carcinoma, Intraductal, Noninfiltrating/metabolism
- Carcinoma, Intraductal, Noninfiltrating/pathology
- Connexin 43/biosynthesis
- Connexin 43/chemistry
- Endothelium, Vascular/metabolism
- Epithelial Cells/metabolism
- Female
- Fibroadenoma/blood supply
- Fibroadenoma/metabolism
- Fibroadenoma/pathology
- Fibrocystic Breast Disease/blood supply
- Fibrocystic Breast Disease/metabolism
- Fibrocystic Breast Disease/pathology
- Humans
- Hyperplasia/metabolism
- Hyperplasia/pathology
- Immunoblotting
- Immunohistochemistry
- Mitogen-Activated Protein Kinase 1/biosynthesis
- Mitogen-Activated Protein Kinase 3/biosynthesis
- Phosphorylation
- Receptor, ErbB-2/biosynthesis
- Up-Regulation
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Affiliation(s)
- Victor E Gould
- Department of Patholgy, Rush Medical College, Chicago, IL 60611, USA
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Kanczuga-Koda L, Sulkowski S, Koda M, Sulkowska M. Alterations in connexin26 expression during colorectal carcinogenesis. Oncology 2005; 68:217-22. [PMID: 16015037 DOI: 10.1159/000086777] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Accepted: 07/05/2004] [Indexed: 12/20/2022]
Abstract
BACKGROUND Gap junctional intercellular communication (GJIC) is a mechanism for direct cell-to-cell signalling and is mediated by gap junctions, which consist of transmembrane proteins called connexins (Cxs). Human colorectal epithelial cells express Cx32 and Cx43. METHODS Tissue samples (152 from colorectal cancer and 75 from adenoma) were investigated by immunohistochemistry, using the antibody for Cx26. Moreover, Cx26 was assessed in normal epithelium of the colon and rectum, adjacent to colorectal cancer. RESULTS In normal epithelium and adenomas, intercellular, punctate staining for Cx26 was observed. In adenomas with severe dysplasia, focally decreased expression of Cx26 was observed. Among 152 colorectal cancers, 55.9% classified only as adenocarcinoma stained positive for Cx26, but mainly cytoplasmic staining was found. We observed a positive correlation between Cx26 expression and tumor G2 grade (p < 0.005). The expression of Cx26 did not correlate with age, sex of patients, tumor localization, lymph node status or tumor size. CONCLUSIONS Our results show that during colorectal carcinogenesis, loss of normal intercellular Cx expression occurs. Furthermore, the cytoplasmic presence of Cx26 could indicate a different role of Cx26 in neoplastic cells than participation in GJIC.
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King TJ, Lampe PD. Altered tumor biology and tumorigenesis in irradiated and chemical carcinogen-treated single and combined connexin32/p27Kip1-deficient mice. CELL COMMUNICATION & ADHESION 2005; 12:293-305. [PMID: 16531324 PMCID: PMC1570041 DOI: 10.1080/15419060500514168] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Connexin32 knockout mice (Cx32-KO) exhibit increased chemical and radiation-induced liver and lung tumorigenesis. This increased tumor incidence is associated with altered tumor biology including enhanced tumor progression and an increased percent of MAPK-active tumors. Likewise, mice lacking the tumor suppressor/cell cycle regulator p27Kip1 exhibit increased tumorigenesis in a variety of tissues following chemical and radiation induction. Interestingly, in a double-deficient mouse model (DKO), additional loss of p27Kip1 in a Cx32-KO background results in attenuation of liver and lung tumorigenesis as well as MAPK activation profiles, suggesting pathway interaction. While these mouse strains exhibit altered liver and lung tumor susceptibility following both chemical (DEN) and radiation (X-ray) induction protocols, comparisons of the resulting tumor incidence, multiplicity, tumor progression, and MAPK activation in response to these two distinct carcinogens underscores the separate influence of each individual gene on both tumor formation and activation of specific oncogenic pathways. Furthermore, these studies demonstrate that different carcinogens interact disparately with Cx32/p27Kip1 genotypic backgrounds in situ resulting in varied tumorigenic response.
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Affiliation(s)
- Timothy J. King
- Molecular Diagnostics Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109
- Department of Pathobiology, University of Washington, Seattle, WA 98195
| | - Paul D. Lampe
- Molecular Diagnostics Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109
- Department of Pathobiology, University of Washington, Seattle, WA 98195
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40
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Tanmahasamut P, Sidell N. Up-regulation of gap junctional intercellular communication and connexin43 expression by retinoic acid in human endometrial stromal cells. J Clin Endocrinol Metab 2005; 90:4151-6. [PMID: 15811935 DOI: 10.1210/jc.2004-0663] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Gap junctions, made up of connexins (Cxs), play fundamental roles in coordinating a number of cellular processes through their ability to directly regulate cell-cell communication. Cx43 is the most widely expressed Cx in the endometrium and is known to be important in a variety of physiological and pathological processes in this tissue. OBJECTIVE In this study, we investigated the ability of the retinoid, all-trans-retinoic acid (RA), to regulate Cx43 expression in human endometrial stromal cells. DESIGN Primary endometrial stromal cells obtained from patients undegoing surgery for infertility workup were treated in vitro with RA and control compounds for different time periods, up to 48 h. Cx43 mRNA and protein levels, protein phosphorylation, and gap junctional intercellular communication (GJIC) were analyzed. RESULTS Treatment of the cells with RA showed a dose-dependent increase in Cx43 expression at both the mRNA and protein levels. In addition, RA induced a relative decrease in the phosphorylated species of Cx43 while causing a corresponding increase in the nonphosphorylated form. Concomitant with these changes, RA-treated cells demonstrated up to a 250% enhancement of GJIC as assessed by dye transfer experiments. Augmentation of GJIC and alterations of Cx43 expression were observed over the same range of RA concentrations. Treatment of cells with the protein kinase C activator 12-O-tetradecanoylphorbol-13-acetate increased the phosphorylated species of Cx43 and correspondingly inhibited GJIC. CONCLUSIONS Phosphorylation of Cx43 is inversely related to GJIC in endometrial stromal cells. Retinoids increase GJIC in endomentrial stromal cells through upregulation of Cx43 expression while inducing a decrease in the phosphorylated species of the protein. The data suggest a novel mechanism by which retinoids can influence endometrial cell biology.
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Affiliation(s)
- Prasong Tanmahasamut
- Division of Research, Department of Gynecology and Obstetrics, Emory University School of Medicine, 1639 Pierce Drive, Atlanta, Georgia 30322, USA
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41
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Steinhoff I, Leykauf K, Bleyl U, Dürst M, Alonso A. Phosphorylation of the gap junction protein Connexin43 in CIN III lesions and cervical carcinomas. Cancer Lett 2005; 235:291-7. [PMID: 15958277 DOI: 10.1016/j.canlet.2005.04.031] [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: 02/03/2005] [Revised: 04/20/2005] [Accepted: 04/24/2005] [Indexed: 11/21/2022]
Abstract
Connexins are proteins that form the connexons, gap junction structures, which allow cells to communicate. Phosphorylation of connexins has been found to impair this communication. Using an antibody specifically recognizing the S279/S282-phosphorylated form of connexin43 (Cx43) for immunohistochemistry, we have analysed Cx43 phosphorylation in normal epithelium, CIN III lesions, and carcinomas of the cervix. We found that in normal epithelium the basal layer was devoid of staining and most of the protein was localized in stratum spinosum and stratum granulosum. In pre-malignant CIN-III lesions Cx43 was strongly phosphorylated, but the basal layer was still negative. In squamous carcinomas, the cells were intensely stained. In these tumours, sites of strong staining were adjacent to less stained regions, suggesting that the tumours are intrinsically heterogeneous. Immunoblotting of proteins extracted from carcinomas with the specific antibody showed the classical pattern of multiple reacting bands, with the appearance of low migrating forms of the protein. Our results suggest that increased S279/S282 phosphorylation of Cx43 is the result of altered tissue structure rather than of cell malignization.
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Affiliation(s)
- Inga Steinhoff
- Pathologisches Institut der Fakultät für Klinische Medizin Mannheim, Ruprecht-Karls-Universität Heidelberg, Theodor-Kutzer-Ufer 1-3, D-68135 Mannheim, Germany
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42
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Vine AL, Leung YM, Bertram JS. Transcriptional regulation of connexin 43 expression by retinoids and carotenoids: similarities and differences. Mol Carcinog 2005; 43:75-85. [PMID: 15754312 DOI: 10.1002/mc.20080] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Gap junctions, connexons, are formed by assembly of trans-membrane connexin proteins and have multiple functions including the coordination of cell responses. Most human tumors are deficient in gap junctional communication (GJC) and restoration of GJC by forced expression of connexins reduces indices of neoplasia. Expression of connexin 43 (Cx43), the most widely-expressed connexin family member, is upregulated by cancer-preventive retinoids and carotenoids in normal and preneoplastic cells; an action considered of mechanistic significance. However, the molecular mechanism for upregulated expression is poorly understood. The retinoic acid receptor antagonist Ro 41-5253 was capable of suppressing retinoid-induction Cx43 luciferase reporter construct in F9 cells, but did not suppress reporter activity induced by the non-pro-vitamin A carotenoids astaxanthin or lycopene, indicating that retinoids have separate mechanisms of gene activation than non-pro-vitamin A carotenoids. Neither class of compound required protein synthesis for induction of Cx43 mRNA, nor was the 5.0 h half-life of Cx43 mRNA altered, indicating direct transcriptional activation. The responsive region was found within -158 bp and +209 bp of the transcription start site; this contains a Sp1/Sp3 GC-box to which Sp1 and Sp3 were bound, as revealed by electrophoretic mobility shift assays (EMSA), but no retinoic acid response element (RARE). Site directed mutagenesis of this GC-box resulted in increased basal levels of transcription and loss of responsiveness to a synthetic retinoid. In this construct astaxanthin and lycopene produced marginally, but not significantly higher, reporter activity than the control.
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Affiliation(s)
- Alex L Vine
- Cancer Research Center of Hawaii, University of Hawaii at Manoa, Honolulu, Hawaii 96813, USA
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43
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Hix LM, Frey DA, McLaws MD, Østerlie M, Lockwood SF, Bertram JS. Inhibition of chemically-induced neoplastic transformation by a novel tetrasodium diphosphate astaxanthin derivative. Carcinogenesis 2005; 26:1634-41. [PMID: 15888493 DOI: 10.1093/carcin/bgi121] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Carotenoids have been implicated in numerous epidemiological studies as being protective against cancer at many sites, and their chemopreventive properties have been confirmed in laboratory studies. Astaxanthin (AST), primarily a carotenoid of marine origin, responsible for the pink coloration of salmon, shrimp and lobster, has received relatively little attention. As with other carotenoids, its highly lipophilic properties complicate delivery to model systems. To overcome this issue we have synthesized a novel tetrasodium diphosphate astaxanthin (pAST) derivative with aqueous dispersibility of 25.21 mg/ml. pAST was delivered to C3H/10T1/2 cells in an aqueous/ethanol solution and compared with non-esterified AST dissolved in tetrahydrofuran. We show pAST to (i) upregulate connexin 43 (Cx43) protein expression; (ii) increase the formation of Cx43 immunoreactive plaques; (iii) upregulate gap junctional intercellular communication (GJIC); and (iv) cause 100% inhibition of methylcholanthrene-induced neoplastic transformation at 10(-6) M. In all these assays, pAST was superior to non-esterified AST itself; in fact, pAST exceeded the potency of all other previously tested carotenoids in this model system. Cleavage of pAST to non-esterified (free) AST and uptake into cells was also verified by HPLC; however, levels of free AST were approximately 100-fold lower than in cells treated with AST itself, suggesting that pAST possesses intrinsic activity. The dual properties of water dispersibility (enabling parenteral administration in vivo) and increased potency should prove extremely useful in the future development of cancer chemopreventive agents.
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Affiliation(s)
- Laura M Hix
- Department of Cell and Molecular Biology, University of Hawaii at Manoa, Honolulu, HI 96822, USA
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44
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Bertram JS, Vine AL. Cancer prevention by retinoids and carotenoids: Independent action on a common target. Biochim Biophys Acta Mol Basis Dis 2005; 1740:170-8. [PMID: 15949684 DOI: 10.1016/j.bbadis.2005.01.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2004] [Revised: 12/29/2004] [Accepted: 01/04/2005] [Indexed: 10/25/2022]
Abstract
Virtually all human tumors are deficient in gap junctional communication (GJC) and the restoration of GJC by forced expression of connexins reduces indices of neoplasia. The expression of connexin 43 (Cx43) is upregulated by cancer-preventive retinoids and carotenoids which correlates with the suppression of carcinogen-induced transformation in 10T1/2 cells. However, the molecular mechanism for upregulated expression is poorly understood. The retinoic acid receptor antagonist, Ro 41-5253, suppressed retinoid-induced Cx43 protein expression in 10T1/2 cells and the induction of a Cx43 luciferase reporter construct in F9 cells, but did not suppress protein expression or reporter activity induced by the non-pro-vitamin A carotenoid astaxanthin. In contrast, Cx43 induction by astaxanthin, but not by a RAR-specific retinoid, was inhibited by GW9662, a PPAR-gamma antagonist. Neither compound required protein synthesis for the induction of Cx43 mRNA, nor was the 5.0 h half-life of Cx43 mRNA altered, indicating direct transcriptional activation. The responsive region was found within -158 bp and +209 bp of the transcription start site. Site directed mutagenesis of a GC-box in this region increased basal levels of transcription and loss of retinoid responsiveness. Simultaneous treatment with a retinoid and beta-carotene or astaxanthin resulted in supra-additive Cx43 expression, again indicating separate mechanisms of gene regulation.
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Affiliation(s)
- John S Bertram
- Cancer Research Center of Hawaii, University of Hawaii at Manoa, 1236 Lauhala St., Honolulu, Hawaii, USA.
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45
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Abstract
Carotenoids and retinoids are chemically related; indeed a major source of vitamin A in humans occurs through enzymic cleavage of beta-carotene. However, most dietary carotenoids cannot be converted into retinoids. Retinoids have demonstrated cancer-preventive activities in humans and experimental models; however, their toxicity has precluded wide-scale clinical use. In contrast, carotenoids are essentially non-toxic and their cancer-preventive activities, although strongly supported by epidemiological studies, have only been satisfactorily demonstrated in experimental systems. We have shown that in an experimental cell culture system consisting of carcinogen-treated 10T1/2 cells, both retinoids and all dietary carotenoids examined can reversibly inhibit neoplastic transformation in the post-initiation phase of carcinogenesis. This activity strongly correlates with their ability to increase gap junctional intercellular communication by up-regulating the expression of the gene CX43 (connexin43). Connexins comprise the structural unit of gap junctions, organelles which allow direct transfer of signals, nutrients and waste products between contacting cells. CX43 is the most widely expressed member of the gap junction family of genes, and we have demonstrated that its expression is strongly down-regulated in human cancers and in several premalignant conditions. When several human tumour cell lines were genetically engineered to conditionally express CX43 under the influence of a tetracycline promoter, their neoplastic phenotype was strongly attenuated. Specifically, induced cells were inhibited from growing in an anchorage-independent manner and, additionally, growth as xenografts in immunocompromised animals was also strongly attenuated. Growth inhibition in suspension was associated both with increased G(1) cell-cycle arrest and with increased apoptosis. We propose a model whereby junctional communication allows the transfer of growth inhibitory signals from normal to neoplastic cells and that retinoids and carotenoids, by increasing signal transfer, act to prevent cancer.
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Affiliation(s)
- J S Bertram
- Cancer Etiology Program, Cancer Research Center of Hawaii, University of Hawaii at Manoa, Honolulu, HI 9681, USA.
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46
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King TJ, Gurley KE, Prunty J, Shin JL, Kemp CJ, Lampe PD. Deficiency in the gap junction protein connexin32 alters p27Kip1 tumor suppression and MAPK activation in a tissue-specific manner. Oncogene 2005; 24:1718-26. [PMID: 15608667 DOI: 10.1038/sj.onc.1208355] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Revised: 11/05/2004] [Accepted: 11/05/2004] [Indexed: 11/09/2022]
Abstract
Connexin32 knockout mice (Cx32-KO) exhibit increased chemical- and radiation-induced liver and lung tumor formation with many lung tumors demonstrating decreased levels of the tumor suppressor p27KIP1. To determine if p27 deficiency alters Cx32-influenced tumorigenesis, we have generated a Cx32/p27 double-deficient mouse strain (DKO) and show here that exposure of these mice to X-ray radiation resulted in an increase or decrease in tumorigenesis depending on the tissue. Several tissues were highly sensitive to loss of p27 tumor suppressor function (intestine, adrenal, pituitary) resulting in an increased overall tumor burden in DKO mice compared to both wild-type (P<0.005) and Cx32-KO mice (P=0.066). However, additional deletion of p27 in a Cx32-KO background resulted in a statistically significant decrease in the liver tumor incidence suggesting that Cx32 and p27 pathways mechanistically interact. Immunohistochemical analysis revealed an increased percentage of Cx32-KO liver and lung tumors harboring active mitogen-activated protein kinase (Erk1, Erk2) pathways in contrast to lower percentages of activated wild-type (P<0.005) and DKO tumors (P=0.027). Increased MAPK activation in liver tumors did not correlate with Ha-ras codon-61 mutation status. This study demonstrates that tissues dependent on Cx32 tumor suppression, such as the liver and lung, exhibit altered tumorigenesis and tumor biology (MAPK pathway activation) related to p27 status.
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Affiliation(s)
- Timothy J King
- Cancer Prevention Research Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
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47
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Koreen I, Elsayed W, Liu Y, Harris A. Tetracycline-regulated expression enables purification and functional analysis of recombinant connexin channels from mammalian cells. Biochem J 2005; 383:111-9. [PMID: 15242349 PMCID: PMC1134049 DOI: 10.1042/bj20040806] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2004] [Revised: 06/29/2004] [Accepted: 07/09/2004] [Indexed: 11/17/2022]
Abstract
Intercellular coupling mediated by gap junction channels composed of connexin protein underlies numerous physiological processes, such as cellular differentiation, tissue synchronization and metabolic homoeostasis. The distinct molecular permeability of junctional channels composed of different connexin isoforms allows cellular control of coupling via regulation of isoform expression. However, the permeability properties of most connexin isoforms have not been well characterized due to the difficulty of manipulating and measuring the diffusible concentrations of cytoplasmic messenger molecules and metabolites, and to a lack of control over channel isoform composition, in vivo. Here we present a method to express and purify active connexin hemichannels of a single isoform or a consistent ratio of two isoforms from cultured cells using the Tet-On inducible expression system and one-step anti-haemagglutinin immunoaffinity purification. The procedure yields 10-20 microg of pure connexin protein from 2.5x10(8) HeLa cells. The purified channels are shown to be useful for in vitro permeability analysis using well established techniques. This method has substantial advantages over existing methods for heterologous connexin expression, such as the ease of co-expression of two isoforms at a constant ratio, consistently high expression levels over many passages, and the ability to study channel properties in situ as well as in purified form. Furthermore, the generic cloning site of the new pBI-GT vector and the commercial availability of anti-haemagglutinin (clone HA-7)-agarose make this affinity tagging and purification procedure easily applicable to other proteins.
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Affiliation(s)
- Irina V. Koreen
- Department of Pharmacology and Physiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, 185 South Orange Ave, Newark, NJ 07103, U.S.A
| | - Wafaa A. Elsayed
- Department of Pharmacology and Physiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, 185 South Orange Ave, Newark, NJ 07103, U.S.A
| | - Yu J. Liu
- Department of Pharmacology and Physiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, 185 South Orange Ave, Newark, NJ 07103, U.S.A
| | - Andrew L. Harris
- Department of Pharmacology and Physiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, 185 South Orange Ave, Newark, NJ 07103, U.S.A
- To whom correspondence should be addressed (email )
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48
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Bravo IG, Alonso A. Mucosal human papillomaviruses encode four different E5 proteins whose chemistry and phylogeny correlate with malignant or benign growth. J Virol 2004; 78:13613-26. [PMID: 15564472 PMCID: PMC533923 DOI: 10.1128/jvi.78.24.13613-13626.2004] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
We performed a phylogenetic study of the E2-L2 region of human mucosal papillomaviruses (PVs) and of the proteins therein encoded. Hitherto, proteins codified in this region were known as E5 proteins. We show that many of these proteins could be spurious translations, according to phylogenetic and chemical coherence criteria between similar protein sequences. We show that there are four separate families of E5 proteins, with different characteristics of phylogeny, chemistry, and rate of evolution. For the sake of clarity, we propose a change in the present nomenclature. E5alpha is present in groups A5, A6, A7, A9, and A11, PVs highly associated with malignant carcinomas of the cervix and penis. E5beta is present in groups A2, A3, A4, and A12, i.e., viruses associated with certain warts. E5gamma is present in group A10, and E5delta is encoded in groups A1, A8, and A10, which are associated with benign transformations. The phylogenetic relationships between mucosal human PVs are the same when considering the oncoproteins E6 and E7 and the E5 proteins and differ from the phylogeny estimated for the structural proteins L1 and L2. Besides, the protein divergence rate is higher in early proteins than in late proteins, increasing in the order L1 < L2 < E6 approximately E7 < E5. Moreover, the same proteins have diverged more rapidly in viruses associated with malignant transformations than in viruses associated with benign transformations. The E5 proteins display, therefore, evolutionary characteristics similar to those of the E6 and E7 oncoproteins. This could reflect a differential involvement of the E5 types in the transformation processes.
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Affiliation(s)
- Ignacio G Bravo
- Deutsches Krebsforschungszentrum, Im Neuenheimer Feld-242, 69120 Heidelberg, Germany.
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Finocchiaro LME, Bumaschny VF, Karara AL, Fiszman GL, Casais CC, Glikin GC. Herpes simplex virus thymidine kinase/ganciclovir system in multicellular tumor spheroids. Cancer Gene Ther 2004; 11:333-45. [PMID: 15107812 DOI: 10.1038/sj.cgt.7700682] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We have developed multicellular spheroids (MCS) established from LM05e and LM3 spontaneous Balb/c-murine mammary adenocarcinoma and B16 C57-murine melanoma derived cell lines as an in vitro model to study the efficacy of the herpes simplex virus thymidine kinase/ganciclovir (HSVtk/GCV) suicide system. We demonstrated for the first time that HSVtk-expressing cells assembled as MCS manifested a GCV resistance phenotype compared to the same cells grown as sparse monolayers. HSVtk-expressing LM05e, LM3 and B16 spheroids were 16-, three- and nine-fold less sensitive to GCV than their respective monolayers, even though they could express transgenes 10-, eight- and five-fold more efficiently. Mixed populations of HSVtk- and their respective beta gal-expressing cells displayed a cell-type specific bystander effect that was higher in monolayers than in MCS. However, HSVtk-expressing cells in two- or three-dimensional cultures were always significantly more sensitive to GCV than the beta gal-expressing counterparts, supporting the feasibility of this suicide approach in vivo. We present evidence showing that HSVtk-expressing tumor cells, when transferred from monolayers to MCS, displayed: (i) lower GCV cytotoxic activity and bystander effect; (ii) higher and efficient expression of genes transferred as lipoplexes; (iii) lower cell proliferation rates; and (iv) changes in intracellular Bax/Bcl-xL rheostat of mitochondria-mediated apoptosis.
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Affiliation(s)
- Liliana M E Finocchiaro
- Unidad de Transferencia Genética, Instituto de Oncología Angel H. Roffo, Universidad de Buenos Aires, Buenos Aires, Argentina.
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Pu P, Xia Z, Yu S, Huang Q. Altered expression of Cx43 in astrocytic tumors. Clin Neurol Neurosurg 2004; 107:49-54. [PMID: 15567553 DOI: 10.1016/j.clineuro.2004.03.006] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2003] [Revised: 03/11/2004] [Accepted: 03/22/2004] [Indexed: 11/22/2022]
Abstract
OBJECTIVE To evaluate the Cx43 expression of astrocytic tumors and correlate their expression with degrees of malignancy and proliferation activity of tumors. METHODS Cx43 expression in eight normal brain tissues, 44 freshly resected astrocytic tumor specimens and four malignant glioma cell lines were examined by Northern blot analysis and immunohistochemical staining. The proliferation activity of tumors was measured by Ki67 labeling index (Ki67LI) with immunostaining. Scrape loading and dye transfer assay was used for examination of gap junction intercellular communication (GJIC) in glioma cell lines. RESULTS Twenty-three out of 44 astrocytic tumors (52%) expressed both Cx43 mRNA and Protein. Cx43 expression was decreased with the ascending of tumor grade and negatively correlated with Ki67LI. GJIC was interrupted in glioma cell lines deficient in Cx43 expression. CONCLUSIONS Cx43 expression level is inversely correlated with the tumor grade and proliferation activity of tumor, suggesting the potential role of Cx43 in the malignant progression of astrocytic tumors.
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Affiliation(s)
- Peiyu Pu
- Department of Neurosurgery, Tianjin Medical University General Hospital, 154 Anshan Road, Tianjin 300052, PR China.
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