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Biological relevance of cell-in-cell in cancers. Biochem Soc Trans 2019; 47:725-732. [PMID: 30850425 PMCID: PMC6490704 DOI: 10.1042/bst20180618] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 02/12/2019] [Accepted: 02/13/2019] [Indexed: 01/20/2023]
Abstract
Cell-in-cell (CIC) is a term used to describe the presence of one, usually living, cell inside another cell that is typically considered non-phagocytic. Examples of this include tumour cells inside tumour cells (homotypic), mesenchymal stem cells inside tumour cells (heterotypic) or immune cells inside tumour cells (heterotypic). CIC formation can occur in cell lines and in tissues and it has been most frequently observed during inflammation and in cancers. Over the past 10 years, many researchers have studied CIC structures and a few different models have been proposed through which they can be formed, including entosis, cannibalism and emperipolesis among others. Recently, our laboratory discovered a role for mutant p53 in facilitating the formation of CIC and promoting genomic instability. These data and research by many others have uncovered a variety of molecules involved in CIC formation and have started to give us an idea of why they are formed and how they could contribute to oncogenic processes. In this perspective, we summarise current literature and speculate on the role of CIC in cancer biology.
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Abstract
Cell-in-cell structures are reported in numerous cancers, and their presence is an indicator for poor prognosis. Mechanistic studies have identified how cancer cells manage to ingest whole neighbouring cells to form such structures, and the consequences of cell-in-cell formation on cancer progression have been elucidated. In this Opinion article, we discuss how two related cell-in-cell processes, cell cannibalism and entosis, are regulated and how these mechanisms promote cancer progression. We propose that cannibalistic activity is a hallmark of cancer that results in part from selection by metabolic stress and serves to feed aggressive cancer cells.
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Affiliation(s)
- Stefano Fais
- Department of Oncology and Molecular Medicine, National Institute of Health, Rome, Italy.
| | - Michael Overholtzer
- Cell Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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3
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Mackay HL, Moore D, Hall C, Birkbak NJ, Jamal-Hanjani M, Karim SA, Phatak VM, Piñon L, Morton JP, Swanton C, Le Quesne J, Muller PAJ. Genomic instability in mutant p53 cancer cells upon entotic engulfment. Nat Commun 2018; 9:3070. [PMID: 30076358 PMCID: PMC6076230 DOI: 10.1038/s41467-018-05368-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 06/29/2018] [Indexed: 01/15/2023] Open
Abstract
Cell-in-cell (CIC) structures are commonly seen in tumours. Their biological significance remains unclear, although they have been associated with more aggressive tumours. Here we report that mutant p53 promotes CIC via live cell engulfment. Engulfed cells physically interfere in cell divisions of host cells and for cells without p53 this leads to host cell death. In contrast, mutant p53 host cells survive, display aberrant divisions, multinucleation and tripolar mitoses. In xenograft studies, CIC-rich p53 mutant/null co-cultures show enhanced tumour growth. Furthermore, our results show that CIC is common within lung adenocarcinomas, is an independent predictor of poor outcome and disease recurrence, is associated with mutant p53 expression and correlated to measures of heterogeneity and genomic instability. These findings suggest that pro-tumorigenic entotic engulfment activity is associated with mutant p53 expression, and the two combined are a key factor in genomic instability.
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Affiliation(s)
- Hannah L Mackay
- MRC Toxicology Unit, Lancaster Road, Leicester, LE1 9HN, UK
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - David Moore
- MRC Toxicology Unit, Lancaster Road, Leicester, LE1 9HN, UK
- Cancer studies, University of Leicester, Leicester, LE1 7RH, UK
| | - Callum Hall
- Cancer Research UK Manchester Institute, The University of Manchester | Alderley Park, Manchester, SK10 4TG, UK
| | - Nicolai J Birkbak
- Translational Cancer Therapeutics Laboratory, The Francis Crick Institute, 1 Midland Rd, London, NW1 1AT, UK
- Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, Paul O'Gorman Building 72 Huntley Street, London, WC1E 6BT, UK
| | - Mariam Jamal-Hanjani
- Department of Medical Oncology, University College London Hospitals, 235 Euston Rd, Fitzrovia, London, NW1 2BU, UK
- CRUK The Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - Saadia A Karim
- Institute of Cancer Sciences, University of Glasgow, Switchback Road, Glasgow, G61 1BD, UK
| | | | - Lucia Piñon
- MRC Toxicology Unit, Lancaster Road, Leicester, LE1 9HN, UK
| | - Jennifer P Morton
- Institute of Cancer Sciences, University of Glasgow, Switchback Road, Glasgow, G61 1BD, UK
- Department of Histopathology, Glenfield Hospital, University Hospitals Leicester NHS Trust, Groby Road, Leicester, LE3 9QP, UK
| | - Charles Swanton
- Translational Cancer Therapeutics Laboratory, The Francis Crick Institute, 1 Midland Rd, London, NW1 1AT, UK
- Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, Paul O'Gorman Building 72 Huntley Street, London, WC1E 6BT, UK
- Department of Medical Oncology, University College London Hospitals, 235 Euston Rd, Fitzrovia, London, NW1 2BU, UK
| | - John Le Quesne
- MRC Toxicology Unit, Lancaster Road, Leicester, LE1 9HN, UK.
- Cancer studies, University of Leicester, Leicester, LE1 7RH, UK.
- Department of Histopathology, Glenfield Hospital, University Hospitals Leicester NHS Trust, Groby Road, Leicester, LE3 9QP, UK.
| | - Patricia A J Muller
- MRC Toxicology Unit, Lancaster Road, Leicester, LE1 9HN, UK.
- Cancer Research UK Manchester Institute, The University of Manchester | Alderley Park, Manchester, SK10 4TG, UK.
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4
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Garanina AS, Kisurina-Evgenieva OP, Erokhina MV, Smirnova EA, Factor VM, Onishchenko GE. Consecutive entosis stages in human substrate-dependent cultured cells. Sci Rep 2017; 7:12555. [PMID: 28970591 PMCID: PMC5624876 DOI: 10.1038/s41598-017-12867-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 09/15/2017] [Indexed: 01/25/2023] Open
Abstract
Entosis, or cell death by invading another cell, is typical for tumor epithelial cells. The formation of cell-in-cell structures is extensively studied in suspension cultures, but remains poorly understood in substrate-dependent cells. Here, we used electron, confocal and time-lapse microscopy in combination with pharmacological inhibition of intracellular components to study the kinetics of entosis using two human substrate-dependent tumor cultures, A431 and MCF7. In total, we identified and characterized five consecutive stages of entosis, which were common for both examined cell lines. We further demonstrated that actin filaments in the entotic as well as invading cells were crucial for entosis. Microtubules and the Golgi apparatus of entotic cells provided membrane expansion required for internalization of the invading cell. Depolymerization of microfilaments and microtubules, and disintegration of the Golgi complex inhibited entosis. We confirmed the presence of adhesive junctions and discovered the formation of desmosomes between the invading and entotic cells. The internalized cell was shown to be degraded due to the lysosomal activation in both cells whereas the disintegration of the Golgi apparatus did not affect the process. Thus, in the substrate-dependent cultures, entosis requires microfilaments, microtubules and the Golgi complex for cell invasion, but not for internalized cell degradation.
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Affiliation(s)
- Anastasiia S Garanina
- Department of Cell Biology and Histology, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Olga P Kisurina-Evgenieva
- Department of Cell Biology and Histology, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Maria V Erokhina
- Department of Cell Biology and Histology, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Elena A Smirnova
- Department of Cell Biology and Histology, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Valentina M Factor
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Galina E Onishchenko
- Department of Cell Biology and Histology, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia.
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5
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Durgan J, Tseng YY, Hamann JC, Domart MC, Collinson L, Hall A, Overholtzer M, Florey O. Mitosis can drive cell cannibalism through entosis. eLife 2017; 6:e27134. [PMID: 28693721 PMCID: PMC5505699 DOI: 10.7554/elife.27134] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 06/13/2017] [Indexed: 12/12/2022] Open
Abstract
Entosis is a form of epithelial cell cannibalism that is prevalent in human cancer, typically triggered by loss of matrix adhesion. Here, we report an alternative mechanism for entosis in human epithelial cells, driven by mitosis. Mitotic entosis is regulated by Cdc42, which controls mitotic morphology. Cdc42 depletion enhances mitotic deadhesion and rounding, and these biophysical changes, which depend on RhoA activation and are phenocopied by Rap1 inhibition, permit subsequent entosis. Mitotic entosis occurs constitutively in some human cancer cell lines and mitotic index correlates with cell cannibalism in primary human breast tumours. Adherent, wild-type cells can act efficiently as entotic hosts, suggesting that normal epithelia may engulf and kill aberrantly dividing neighbours. Finally, we report that Paclitaxel/taxol promotes mitotic rounding and subsequent entosis, revealing an unconventional activity of this drug. Together, our data uncover an intriguing link between cell division and cannibalism, of significance to both cancer and chemotherapy.
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Affiliation(s)
- Joanne Durgan
- The Babraham Institute, Cambridge, United Kingdom
- Memorial Sloan Kettering Cancer Center, New York, United States
| | - Yun-Yu Tseng
- Memorial Sloan Kettering Cancer Center, New York, United States
- Weill Graduate School of Medical Sciences, Cornell University, New York, United States
| | - Jens C Hamann
- Memorial Sloan Kettering Cancer Center, New York, United States
- Louis V Gerstner Jr Graduate School of Biomedical Sciences, New York, United States
| | | | | | - Alan Hall
- Memorial Sloan Kettering Cancer Center, New York, United States
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Balvan J, Gumulec J, Raudenska M, Krizova A, Stepka P, Babula P, Kizek R, Adam V, Masarik M. Oxidative Stress Resistance in Metastatic Prostate Cancer: Renewal by Self-Eating. PLoS One 2015; 10:e0145016. [PMID: 26671576 PMCID: PMC4679176 DOI: 10.1371/journal.pone.0145016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 11/25/2015] [Indexed: 12/15/2022] Open
Abstract
Resistant cancer phenotype is a key obstacle in the successful therapy of prostate cancer. The primary aim of our study was to explore resistance mechanisms in the advanced type of prostate cancer cells (PC-3) and to clarify the role of autophagy in these processes. We performed time-lapse experiment (48 hours) with ROS generating plumbagin by using multimodal holographic microscope. Furthermore, we also performed the flow-cytometric analysis and the qRT-PCR gene expression analysis at 12 selected time points. TEM and confocal microscopy were used to verify the results. We found out that autophagy (namely mitophagy) is an important resistance mechanism. The major ROS producing mitochondria were coated by an autophagic membrane derived from endoplasmic reticulum and degraded. According to our results, increasing ROS resistance may be also accompanied by increased average cell size and polyploidization, which seems to be key resistance mechanism when connected with an escape from senescence. Many different types of cell-cell interactions were recorded including entosis, vesicular transfer, eating of dead or dying cells, and engulfment and cannibalism of living cells. Entosis was disclosed as a possible mechanism of polyploidization and enabled the long-term survival of cancer cells. Significantly reduced cell motility was found after the plumbagin treatment. We also found an extensive induction of pluripotency genes expression (NANOG, SOX2, and POU5F1) at the time-point of 20 hours. We suppose, that overexpression of pluripotency genes in the portion of prostate tumour cell population exposed to ROS leads to higher developmental plasticity and capability to faster respond to changes in the extracellular environment that could ultimately lead to an alteration of cell fate.
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Affiliation(s)
- Jan Balvan
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University / Kamenice 5, CZ-625 00, Brno, Czech Republic
- Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00, Brno, Czech Republic
| | - Jaromir Gumulec
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University / Kamenice 5, CZ-625 00, Brno, Czech Republic
- Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00, Brno, Czech Republic
| | - Martina Raudenska
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University / Kamenice 5, CZ-625 00, Brno, Czech Republic
- Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00, Brno, Czech Republic
| | - Aneta Krizova
- Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00, Brno, Czech Republic
- TESCAN Brno, s.r.o., Brno, Czech Republic
| | - Petr Stepka
- Department of Physiology, Faculty of Medicine, Masaryk University / Kamenice 5, CZ-625 00, Brno, Czech Republic
| | - Petr Babula
- Department of Physiology, Faculty of Medicine, Masaryk University / Kamenice 5, CZ-625 00, Brno, Czech Republic
| | - Rene Kizek
- Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00, Brno, Czech Republic
- Department of Chemistry and Biochemistry, Mendel University in Brno / Zemedelska 1, CZ-613 00, Brno, Czech Republic
| | - Vojtech Adam
- Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00, Brno, Czech Republic
- Department of Chemistry and Biochemistry, Mendel University in Brno / Zemedelska 1, CZ-613 00, Brno, Czech Republic
| | - Michal Masarik
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University / Kamenice 5, CZ-625 00, Brno, Czech Republic
- * E-mail:
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7
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Yap YW, Llanos RM, La Fontaine S, Cater MA, Beart PM, Cheung NS. Comparative Microarray Analysis Identifies Commonalities in Neuronal Injury: Evidence for Oxidative Stress, Dysfunction of Calcium Signalling, and Inhibition of Autophagy-Lysosomal Pathway. Neurochem Res 2015; 41:554-67. [PMID: 26318862 DOI: 10.1007/s11064-015-1666-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 07/14/2015] [Accepted: 07/14/2015] [Indexed: 12/21/2022]
Abstract
Mitochondrial dysfunction, ubiquitin-proteasomal system impairment and excitotoxicity occur during the injury and death of neurons in neurodegenerative conditions. The aim of this work was to elucidate the cellular mechanisms that are universally altered by these conditions. Through overlapping expression profiles of rotenone-, lactacystin- and N-methyl-D-aspartate-treated cortical neurons, we have identified three affected biological processes that are commonly affected; oxidative stress, dysfunction of calcium signalling and inhibition of the autophagic-lysosomal pathway. These data provides many opportunities for therapeutic intervention in neurodegenerative conditions, where mitochondrial dysfunction, proteasomal inhibition and excitotoxicity are evident.
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Affiliation(s)
- Yann Wan Yap
- Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, VIC, 3125, Australia
| | - Roxana M Llanos
- Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, VIC, 3125, Australia
| | - Sharon La Fontaine
- Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, VIC, 3125, Australia.,Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Michael A Cater
- Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, VIC, 3125, Australia
| | - Philip M Beart
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Nam Sang Cheung
- Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, VIC, 3125, Australia.
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8
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Nakano I. Engulfing losers by winners in cancer: do cancer stem cells catch eat-me signals from noncancer stem cells? Future Oncol 2015; 10:1335-8. [PMID: 25052743 DOI: 10.2217/fon.14.66] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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9
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Sun Q, Cibas ES, Huang H, Hodgson L, Overholtzer M. Induction of entosis by epithelial cadherin expression. Cell Res 2014; 24:1288-98. [PMID: 25342558 DOI: 10.1038/cr.2014.137] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 03/07/2014] [Accepted: 07/30/2014] [Indexed: 12/17/2022] Open
Abstract
Cell engulfment typically targets dead or dying cells for clearance from metazoan tissues. However, recent evidence demonstrates that live cells can also be targeted and that engulfment can cause cell death. Entosis is one mechanism proposed to mediate the engulfment and killing of live tumor cells by their neighbors, an activity often referred to as cell cannibalism. Here we report that the expression of exogenous epithelial cadherin proteins (E- or P-cadherin) in human breast tumor cells lacking endogenous expression of epithelial cadherins induces entosis and inhibits transformed growth. Entosis induced by cadherin expression is associated with the polarized distribution of Rho and Rho-kinase (ROCK) activity within entotic cells, which is dependent on p190A RhoGAP activity. ROCK inhibition or downregulation of p190A RhoGAP expression reduces entosis and increases the transformed growth of epithelial cadherin-expressing tumor cells. These data define new cell systems for the study of entosis, and identify entosis as a mechanism of cell cannibalism that is induced by the establishment of epithelial adhesion and inhibits transformed growth.
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Affiliation(s)
- Qiang Sun
- 1] Laboratory of Cell Engineering, Institute of Biotechnology, Beijing 100071, China [2] Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | - Edmund S Cibas
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Hongyan Huang
- Department of Oncology, Beijing Shijitan Hospital of Capital Medical University, 10 TIEYI Road, Beijing 100038, China
| | - Louis Hodgson
- Department of Anatomy and Structural Biology and Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY, USA
| | - Michael Overholtzer
- 1] Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA [2] BCMB Allied Program, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA
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10
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CCAAT-enhancer binding protein-β expression and elevation in Alzheimer's disease and microglial cell cultures. PLoS One 2014; 9:e86617. [PMID: 24466171 PMCID: PMC3899300 DOI: 10.1371/journal.pone.0086617] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 12/16/2013] [Indexed: 01/24/2023] Open
Abstract
CCAAT-enhancer binding proteins are transcription factors that help to regulate a wide range of inflammatory mediators, as well as several key elements of energy metabolism. Because C/EBPs are expressed by rodent astrocytes and microglia, and because they are induced by pro-inflammatory cytokines that are chronically upregulated in the Alzheimer’s disease (AD) cortex, we have investigated whether C/EBPs are expressed and upregulated in the AD cortex. Here, we demonstrate for the first time that C/EBPβ can be detected by Western blots in AD and nondemented elderly (ND) cortex, and that it is significantly increased in AD cortical samples. In situ, C/EBPβ localizes immunohistochemically to microglia. In microglia cultured from rapid autopsies of elderly patient’s brains and in the BV-2 murine microglia cell line, we have shown that C/EBPβ can be upregulated by C/EBP-inducing cytokines or lipopolysaccharide and exhibits nuclear translocation possibly indicating functional activity. Given the known co-regulatory role of C/EBPs in pivotal inflammatory mechanisms, many of which are present in AD, we propose that upregulation of C/EBPs in the AD brain could be an important orchestrator of pathogenic changes.
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11
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Does entosis curb the detached cancer cells better? Oral Oncol 2013; 50:e9-11. [PMID: 24361116 DOI: 10.1016/j.oraloncology.2013.11.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 11/28/2013] [Indexed: 11/22/2022]
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12
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Peña-Altamira E, Polazzi E, Moretto E, Lauriola M, Monti B. The transcription factor CCAAT enhancer-binding protein β protects rat cerebellar granule neurons from apoptosis through its transcription-activating isoforms. Eur J Neurosci 2013; 39:176-85. [PMID: 24438488 DOI: 10.1111/ejn.12407] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 10/02/2013] [Accepted: 10/04/2013] [Indexed: 01/07/2023]
Abstract
CCAAT enhancer-binding protein β is a transcription factor that is involved in many brain processes, although its role in neuronal survival/death remains unclear. By using primary cultures of rat cerebellar granule neurons, we have shown here that CCAAT enhancer-binding protein β is present as all of its isoforms: the transcriptional activators liver activator proteins 1 and 2, and the transcriptional inhibitor liver inhibitory protein. We have also shown that liver activator protein 1 undergoes post-translational modifications, such as phosphorylation and sumoylation. These isoforms have different subcellular localizations, liver activator protein 2 being found in the cytosolic fraction only, liver inhibitory protein in the nucleus only, and liver activator protein 1 in both fractions. Through neuronal apoptosis induction by shifting mature cerebellar granule neurons to low-potassium medium, we have demonstrated that nuclear liver activator protein 1 expression decreases and its phosphorylation disappears, whereas liver inhibitory protein levels increase in the nuclear fraction, suggesting a pro-survival role for liver activator protein transcriptional activation and a pro-apoptotic role for liver inhibitory protein transcriptional inhibition. To confirm this, we transfected cerebellar granule neurons with plasmids expressing liver activator protein 1, liver activator protein 2, or liver inhibitory protein respectively, and observed that both liver activator proteins, which increase CCAAT-dependent transcription, but not liver inhibitory protein, counteracted apoptosis, thus demonstrating the pro-survival role of liver activator proteins. These data significantly improve our current understanding of the role of CCAAT enhancer-binding protein β in neuronal survival/apoptosis.
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Affiliation(s)
- Emiliano Peña-Altamira
- Department of Pharmacy and BioTechnology, University of Bologna, Ex-BES Building, Via Selmi 3, Bologna, 40126, Italy
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