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Perez-Gianmarco L, Kukley M. Understanding the Role of the Glial Scar through the Depletion of Glial Cells after Spinal Cord Injury. Cells 2023; 12:1842. [PMID: 37508505 PMCID: PMC10377788 DOI: 10.3390/cells12141842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 06/30/2023] [Accepted: 07/11/2023] [Indexed: 07/30/2023] Open
Abstract
Spinal cord injury (SCI) is a condition that affects between 8.8 and 246 people in a million and, unlike many other neurological disorders, it affects mostly young people, causing deficits in sensory, motor, and autonomic functions. Promoting the regrowth of axons is one of the most important goals for the neurological recovery of patients after SCI, but it is also one of the most challenging goals. A key event after SCI is the formation of a glial scar around the lesion core, mainly comprised of astrocytes, NG2+-glia, and microglia. Traditionally, the glial scar has been regarded as detrimental to recovery because it may act as a physical barrier to axon regrowth and release various inhibitory factors. However, more and more evidence now suggests that the glial scar is beneficial for the surrounding spared tissue after SCI. Here, we review experimental studies that used genetic and pharmacological approaches to ablate specific populations of glial cells in rodent models of SCI in order to understand their functional role. The studies showed that ablation of either astrocytes, NG2+-glia, or microglia might result in disorganization of the glial scar, increased inflammation, extended tissue degeneration, and impaired recovery after SCI. Hence, glial cells and glial scars appear as important beneficial players after SCI.
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Affiliation(s)
- Lucila Perez-Gianmarco
- Achucarro Basque Center for Neuroscience, 48940 Leioa, PC, Spain
- Department of Neurosciences, University of the Basque Country, 48940 Leioa, PC, Spain
| | - Maria Kukley
- Achucarro Basque Center for Neuroscience, 48940 Leioa, PC, Spain
- IKERBASQUE Basque Foundation for Science, 48009 Bilbao, PC, Spain
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2
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Day MA, Jarrom D, Rajah N, Searle PF, Hyde EI, White SA. Oxygen-insensitive nitroreductase E. coli NfsA, but not NfsB, is inhibited by fumarate. Proteins 2023; 91:585-592. [PMID: 36443029 PMCID: PMC10953011 DOI: 10.1002/prot.26451] [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: 08/19/2022] [Revised: 11/23/2022] [Accepted: 11/25/2022] [Indexed: 11/30/2022]
Abstract
Escherichia coli NfsA and NfsB are founding members of two flavoprotein families that catalyze the oxygen-insensitive reduction of nitroaromatics and quinones by NAD(P)H. This reduction is required for the activity of nitrofuran antibiotics and the enzymes have also been proposed for use with nitroaromatic prodrugs in cancer gene therapy and biocatalysis, but the roles of the proteins in vivo in bacteria are not known. NfsA is NADPH-specific whereas NfsB can also use NADH. The crystal structures of E. coli NfsA and NfsB and several analogs have been determined previously. In our crystal trials, we unexpectedly observed NfsA bound to fumarate. We here present the X-ray structure of the E. coli NfsA-fumarate complex and show that fumarate acts as a weak inhibitor of NfsA but not of NfsB. The structural basis of this differential inhibition is conserved in the two protein families and occurs at fumarate concentrations found in vivo, so impacting the efficacy of these proteins.
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Affiliation(s)
- Martin A. Day
- School of BiosciencesUniversity of BirminghamBirminghamUK
- Institute for Cancer and Genomic SciencesUniversity of BirminghamBirminghamUK
| | - David Jarrom
- School of BiosciencesUniversity of BirminghamBirminghamUK
| | - Navina Rajah
- School of BiosciencesUniversity of BirminghamBirminghamUK
| | - Peter F. Searle
- Institute for Cancer and Genomic SciencesUniversity of BirminghamBirminghamUK
| | - Eva I. Hyde
- School of BiosciencesUniversity of BirminghamBirminghamUK
| | - Scott A. White
- School of BiosciencesUniversity of BirminghamBirminghamUK
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3
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Labbaf Z, Petratou K, Ermlich L, Backer W, Tarbashevich K, Reichman-Fried M, Luschnig S, Schulte-Merker S, Raz E. A robust and tunable system for targeted cell ablation in developing embryos. Dev Cell 2022; 57:2026-2040.e5. [PMID: 35914525 DOI: 10.1016/j.devcel.2022.07.008] [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: 02/01/2022] [Revised: 05/10/2022] [Accepted: 07/07/2022] [Indexed: 11/03/2022]
Abstract
Cell ablation is a key method in the research fields of developmental biology, tissue regeneration, and tissue homeostasis. Eliminating specific cell populations allows for characterizing interactions that control cell differentiation, death, behavior, and spatial organization of cells. Current methodologies for inducing cell death suffer from relatively slow kinetics, making them unsuitable for analyzing rapid events and following primary and immediate consequences of the ablation. To address this, we developed a cell-ablation system that is based on bacterial toxin/anti-toxin proteins and enables rapid and cell-autonomous elimination of specific cell types and organs in zebrafish embryos. A unique feature of this system is that it uses an anti-toxin, which allows for controlling the degree and timing of ablation and the resulting phenotypes. The transgenic zebrafish generated in this work represent a highly efficient tool for cell ablation, and this approach is applicable to other model organisms as demonstrated here for Drosophila.
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Affiliation(s)
- Zahra Labbaf
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster 48149, Germany
| | - Kleio Petratou
- Institute for Cardiovascular Organogenesis and Regeneration, Faculty of Medicine, Münster 48149, Germany
| | - Laura Ermlich
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster 48149, Germany
| | - Wilko Backer
- Institute for Integrative Cell Biology and Physiology, University of Münster, Münster 48149, Germany
| | - Katsiaryna Tarbashevich
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster 48149, Germany
| | - Michal Reichman-Fried
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster 48149, Germany
| | - Stefan Luschnig
- Institute for Integrative Cell Biology and Physiology, University of Münster, Münster 48149, Germany
| | - Stefan Schulte-Merker
- Institute for Cardiovascular Organogenesis and Regeneration, Faculty of Medicine, Münster 48149, Germany
| | - Erez Raz
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster 48149, Germany.
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4
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Sharrock AV, Mulligan TS, Hall KR, Williams EM, White DT, Zhang L, Emmerich K, Matthews F, Nimmagadda S, Washington S, Le KD, Meir-Levi D, Cox OL, Saxena MT, Calof AL, Lopez-Burks ME, Lander AD, Ding D, Ji H, Ackerley DF, Mumm JS. NTR 2.0: a rationally engineered prodrug-converting enzyme with substantially enhanced efficacy for targeted cell ablation. Nat Methods 2022; 19:205-215. [PMID: 35132245 PMCID: PMC8851868 DOI: 10.1038/s41592-021-01364-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 11/29/2021] [Indexed: 11/12/2022]
Abstract
Transgenic expression of bacterial nitroreductase (NTR) enzymes sensitizes eukaryotic cells to prodrugs such as metronidazole (MTZ), enabling selective cell-ablation paradigms that have expanded studies of cell function and regeneration in vertebrates. However, first-generation NTRs required confoundingly toxic prodrug treatments to achieve effective cell ablation, and some cell types have proven resistant. Here we used rational engineering and cross-species screening to develop an NTR variant, NTR 2.0, which exhibits ~100-fold improvement in MTZ-mediated cell-specific ablation efficacy, eliminating the need for near-toxic prodrug treatment regimens. NTR 2.0 therefore enables sustained cell-loss paradigms and ablation of previously resistant cell types. These properties permit enhanced interrogations of cell function, extended challenges to the regenerative capacities of discrete stem cell niches, and novel modeling of chronic degenerative diseases. Accordingly, we have created a series of bipartite transgenic reporter/effector resources to facilitate dissemination of NTR 2.0 to the research community.
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Affiliation(s)
- Abigail V Sharrock
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
| | - Timothy S Mulligan
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Kelsi R Hall
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
| | - Elsie M Williams
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
| | - David T White
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Liyun Zhang
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Kevin Emmerich
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Frazer Matthews
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Saumya Nimmagadda
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Selena Washington
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Katherine D Le
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Danielle Meir-Levi
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Olivia L Cox
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Meera T Saxena
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
- Luminomics, Baltimore, MD, USA
| | - Anne L Calof
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
- Center for Complex Biological Systems, University of California, Irvine, CA, USA
| | - Martha E Lopez-Burks
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
- Center for Complex Biological Systems, University of California, Irvine, CA, USA
| | - Arthur D Lander
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
- Center for Complex Biological Systems, University of California, Irvine, CA, USA
| | - Ding Ding
- Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Hongkai Ji
- Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - David F Ackerley
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand.
- Centre for Biodiscovery and Maurice Wilkins Centre for Molecular Biodiscovery, Victoria University of Wellington, Wellington, New Zealand.
| | - Jeff S Mumm
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA.
- The Center for Nanomedicine, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA.
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA.
- Department of Genetic Medicine, McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University, Baltimore, MD, USA.
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5
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Flavin oxidation state impacts on nitrofuran antibiotic binding orientation in nitroreductases. Biochem J 2021; 478:3423-3428. [PMID: 34554213 DOI: 10.1042/bcj20210489] [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: 07/23/2021] [Revised: 09/03/2021] [Accepted: 09/06/2021] [Indexed: 11/17/2022]
Abstract
Nitroreductases catalyse the NAD(P)H-dependent nitro reduction in nitrofuran antibiotics, which activates them into cytotoxic molecules leading to cell death. The design of new effective nitrofuran antibiotics relies on knowledge of the kinetic mechanism and nitrofuran binding mode of microbial nitroreductases NfsA and NfsB. This has been hampered by multiple co-crystallisation studies revealing ligand binding in non-electron transfer competent states. In a recent study by Day et al. (2021) the authors investigated the likely reaction mechanism and mode of nitrofurantoin binding to NfsA using potentiometry, global kinetics analysis, crystallography and molecular dynamics simulations. Their findings suggest nitrofurantoin reduction proceeds via a direct hydride transfer from reduced FMN, while the crystallographic binding orientation is an inhibitory complex. Molecular dynamics simulations suggest ligand binding orientations is dependent on the oxidation state of the FMN. This study highlights the importance of utilising computational studies alongside traditional crystallographic approaches, when multiple stable ligand binding orientations can occur.
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6
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The structures of E. coli NfsA bound to the antibiotic nitrofurantoin; to 1,4-benzoquinone and to FMN. Biochem J 2021; 478:2601-2617. [PMID: 34142705 PMCID: PMC8286842 DOI: 10.1042/bcj20210160] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 06/14/2021] [Accepted: 06/17/2021] [Indexed: 01/23/2023]
Abstract
NfsA is a dimeric flavoprotein that catalyses the reduction in nitroaromatics and quinones by NADPH. This reduction is required for the activity of nitrofuran antibiotics. The crystal structure of free Escherichia coli NfsA and several homologues have been determined previously, but there is no structure of the enzyme with ligands. We present here crystal structures of oxidised E. coli NfsA in the presence of several ligands, including the antibiotic nitrofurantoin. Nitrofurantoin binds with the furan ring, rather than the nitro group that is reduced, near the N5 of the FMN. Molecular dynamics simulations show that this orientation is only favourable in the oxidised enzyme, while potentiometry suggests that little semiquinone is formed in the free protein. This suggests that the reduction occurs by direct hydride transfer from FMNH− to nitrofurantoin bound in the reverse orientation to that in the crystal structure. We present a model of nitrofurantoin bound to reduced NfsA in a viable hydride transfer orientation. The substrate 1,4-benzoquinone and the product hydroquinone are positioned close to the FMN N5 in the respective crystal structures with NfsA, suitable for reaction, but are mobile within the active site. The structure with a second FMN, bound as a ligand, shows that a mobile loop in the free protein forms a phosphate-binding pocket. NfsA is specific for NADPH and a similar conformational change, forming a phosphate-binding pocket, is likely to also occur with the natural cofactor.
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7
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Bergemann D, Massoz L, Bourdouxhe J, Carril Pardo CA, Voz ML, Peers B, Manfroid I. Nifurpirinol: A more potent and reliable substrate compared to metronidazole for nitroreductase-mediated cell ablations. Wound Repair Regen 2018; 26:238-244. [PMID: 29663654 DOI: 10.1111/wrr.12633] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 04/10/2018] [Indexed: 12/21/2022]
Abstract
The zebrafish is a popular animal model with well-known regenerative capabilities. To study regeneration in this fish, the nitroreductase/metronidazole-mediated system is widely used for targeted ablation of various cell types. Nevertheless, we highlight here some variability in ablation efficiencies with the metronidazole prodrug that led us to search for a more efficient and reliable compound. Herein, we present nifurpirinol, another nitroaromatic antibiotic, as a more potent prodrug compared to metronidazole to trigger cell-ablation in nitroreductase expressing transgenic models. We show that nifurpirinol induces robust and reliable ablations at concentrations 2,000 fold lower than metronidazole and three times below its own toxic concentration. We confirmed the efficiency of nifurpirinol in triggering massive ablation of three different cell types: the pancreatic beta cells, osteoblasts, and dopaminergic neurons. Our results identify nifurpirinol as a very potent prodrug for the nitroreductase-mediated ablation system and suggest that its use could be extended to many other cell types, especially if difficult to ablate, or when combined pharmacological treatments are desired.
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Affiliation(s)
- David Bergemann
- Zebrafish Development and Disease Models Laboratory/GIGA, University of Liège, Liege, Belgium
| | - Laura Massoz
- Zebrafish Development and Disease Models Laboratory/GIGA, University of Liège, Liege, Belgium
| | - Jordane Bourdouxhe
- Zebrafish Development and Disease Models Laboratory/GIGA, University of Liège, Liege, Belgium
| | - Claudio A Carril Pardo
- Zebrafish Development and Disease Models Laboratory/GIGA, University of Liège, Liege, Belgium
| | - Marianne L Voz
- Zebrafish Development and Disease Models Laboratory/GIGA, University of Liège, Liege, Belgium
| | - Bernard Peers
- Zebrafish Development and Disease Models Laboratory/GIGA, University of Liège, Liege, Belgium
| | - Isabelle Manfroid
- Zebrafish Development and Disease Models Laboratory/GIGA, University of Liège, Liege, Belgium
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8
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Abstract
INTRODUCTION Over the past decade, it has become clear that long-term engraftment of any ex vivo expanded cell product transplanted into injured myocardium is modest and all therapeutic regeneration is mediated by stimulation of endogenous repair rather than differentiation of transplanted cells into working myocardium. Given that increasing the retention of transplanted cells boosts myocardial function, focus on the fundamental mechanisms limiting retention and survival of transplanted cells may enable strategies to help to restore normal cardiac function. Areas covered: This review outlines the challenges confronting cardiac engraftment of ex vivo expanded cells and explores means of enhancing cell-mediated repair of injured myocardium. Expert opinion: Stem cell therapy has already come a long way in terms of regenerating damaged hearts though the poor retention of transplanted cells limits the full potential of truly cardiotrophic cell products. Multifaceted strategies directed towards fundamental mechanisms limiting the long-term survival of transplanted cells will be needed to enhance transplanted cell retention and cell-mediated repair of damaged myocardium for cardiac cell therapy to reach its full potential.
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Affiliation(s)
| | - Darryl R Davis
- a University of Ottawa Heart Institute , Ottawa , ON , Canada
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9
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Immunomodulation-accelerated neuronal regeneration following selective rod photoreceptor cell ablation in the zebrafish retina. Proc Natl Acad Sci U S A 2017; 114:E3719-E3728. [PMID: 28416692 DOI: 10.1073/pnas.1617721114] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Müller glia (MG) function as inducible retinal stem cells in zebrafish, completely repairing the eye after damage. The innate immune system has recently been shown to promote tissue regeneration in which classic wound-healing responses predominate. However, regulatory roles for leukocytes during cellular regeneration-i.e., selective cell-loss paradigms akin to degenerative disease-are less well defined. To investigate possible roles innate immune cells play during retinal cell regeneration, we used intravital microscopy to visualize neutrophil, macrophage, and retinal microglia responses to induced rod photoreceptor apoptosis. Neutrophils displayed no reactivity to rod cell loss. Peripheral macrophage cells responded to rod cell loss, as evidenced by morphological transitions and increased migration, but did not enter the retina. Retinal microglia displayed multiple hallmarks of immune cell activation: increased migration, translocation to the photoreceptor cell layer, proliferation, and phagocytosis of dying cells. To test function during rod cell regeneration, we coablated microglia and rod cells or applied immune suppression and quantified the kinetics of (i) rod cell clearance, (ii) MG/progenitor cell proliferation, and (iii) rod cell replacement. Coablation and immune suppressants applied before cell loss caused delays in MG/progenitor proliferation rates and slowed the rate of rod cell replacement. Conversely, immune suppressants applied after cell loss had been initiated led to accelerated photoreceptor regeneration kinetics, possibly by promoting rapid resolution of an acute immune response. Our findings suggest that microglia control MG responsiveness to photoreceptor loss and support the development of immune-targeted therapeutic strategies for reversing cell loss associated with degenerative retinal conditions.
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10
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Guan X. Metabolic Activation and Drug Targeting. Drug Deliv 2016. [DOI: 10.1002/9781118833322.ch17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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11
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Abstract
Cancer is a multifactorial disease and is one of the leading causes of death worldwide. The contributing factors include specific genetic background, chronic exposure to various environmental stresses and improper diet. All these risk factors lead to the accumulation of molecular changes or mutations in some important proteins in cells which contributes to the initiation of carcinogenesis. Chemotherapy is an effective treatment against cancer but undesirable chemotherapy reactions and the development of resistance to drugs which results in multi-drug resistance (MDR) are the major obstacles in cancer chemotherapy. Strategies which are in practice with limited success include alternative formulations e.g., liposomes, resistance modulation e.g., PSC833, antidotes/toxicity modifiers e.g., ICRF-187 and gene therapy. Targeted therapy is gaining importance due to its specificity towards cancer cells while sparing toxicity to off-target cells. The scope of this review involves the various strategies involved in targeted therapy like-monoclonal antibodies, prodrug, small molecule inhibitors and nano-particulate antibody conjugates.
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Affiliation(s)
- Viswanadha Vijaya Padma
- Department of Biotechnology, Bharathiar University, 641 046, Coimbatore, Tamil Nadu, India. .,Department of Health and Nutrition Biotechnology, Asia University, 413, Taichung, Taiwan.
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12
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Obata F, Tanaka S, Kashio S, Tsujimura H, Sato R, Miura M. Induction of rapid and selective cell necrosis in Drosophila using Bacillus thuringiensis Cry toxin and its silkworm receptor. BMC Biol 2015; 13:48. [PMID: 26152191 PMCID: PMC4495774 DOI: 10.1186/s12915-015-0160-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 06/19/2015] [Indexed: 12/27/2022] Open
Abstract
Background Genetic ablation of target cells is a powerful tool to study the origins and functions of cells, tissue regeneration, or pathophysiology in a human disease model in vivo. Several methods for selective cell ablation by inducing apoptosis have been established, using exogenous toxins or endogenous proapoptotic genes. However, their application is limited to cells with intact apoptotic machinery. Results Herein, we established a method for inducing rapid and selective cell necrosis by the pore-forming bacterial toxin Cry1Aa, which is specifically active in cells expressing the Cry1Aa receptor (CryR) derived from the silkworm Bombyx mori. We demonstrated that overexpressing CryR in Drosophila melanogaster tissues induced rapid cell death of CryR-expressing cells only, in the presence of Cry1Aa toxin. Cry/CryR system was effective against both proliferating cells in imaginal discs and polyploid postmitotic cells in the fat body. Live imaging analysis of cell ablation revealed swelling and subsequent osmotic lysis of CryR-positive cells after 30 min of incubation with Cry1Aa toxin. Osmotic cell lysis was still triggered when apoptosis, JNK activation, or autophagy was inhibited, suggesting that Cry1Aa-induced necrotic cell death occurred independently of these cellular signaling pathways. Injection of Cry1Aa into the body cavity resulted in specific ablation of CryR-expressing cells, indicating the usefulness of this method for in vivo cell ablation. Conclusions With Cry toxins from Bacillus thuringiensis, we developed a novel method for genetic induction of cell necrosis. Our system provides a “proteinous drill” for killing target cells through physical injury of the cell membrane, which can potentially be used to ablate any cell type in any organisms, even those that are resistant to apoptosis or JNK-dependent programmed cell death. Electronic supplementary material The online version of this article (doi:10.1186/s12915-015-0160-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Fumiaki Obata
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
| | - Shiho Tanaka
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo, 184-8588, Japan.
| | - Soshiro Kashio
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
| | - Hidenobu Tsujimura
- Developmental Biology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo, 183-8509, Japan.
| | - Ryoichi Sato
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo, 184-8588, Japan.
| | - Masayuki Miura
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan. .,CREST, Japan Agency for Medical Research and Development, 20F Yomiuri Shimbun Bldg. 1-7-1 Otemachi, Chiyoda-ku, Tokyo, 100-0004, Japan.
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Jones BS, Lamb LS, Goldman F, Di Stasi A. Improving the safety of cell therapy products by suicide gene transfer. Front Pharmacol 2014; 5:254. [PMID: 25505885 PMCID: PMC4245885 DOI: 10.3389/fphar.2014.00254] [Citation(s) in RCA: 150] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 10/31/2014] [Indexed: 01/02/2023] Open
Abstract
Adoptive T-cell therapy can involve donor lymphocyte infusion after allogeneic hematopoietic stem cell transplantation, the administration of tumor infiltrating lymphocyte expanded ex-vivo, or more recently the use of T cell receptor or chimeric antigen receptor redirected T cells. However, cellular therapies can pose significant risks, including graft-vs.-host-disease and other on and off-target effects, and therefore strategies need to be implemented to permanently reverse any sign of toxicity. A suicide gene is a genetically encoded molecule that allows selective destruction of adoptively transferred cells. Suicide gene addition to cellular therapeutic products can lead to selective ablation of gene-modified cells, preventing collateral damage to contiguous cells and/or tissues. The “ideal” suicide gene would ensure the safety of gene modified cellular applications by granting irreversible elimination of “all” and “only” the cells responsible for the unwanted toxicity. This review presents the suicide gene safety systems reported to date, with a focus on the state-of-the-art and potential applications regarding two of the most extensively validated suicide genes, including the clinical setting: herpes-simplex-thymidine-kinase and inducible-caspase-9.
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Affiliation(s)
- Benjamin S Jones
- Bone Marrow Transplantation and Cellular Therapy Unit, Division of Hematology-Oncology, Department of Medicine, The University of Alabama at Birmingham Birmingham, AL, USA
| | - Lawrence S Lamb
- Bone Marrow Transplantation and Cellular Therapy Unit, Division of Hematology-Oncology, Department of Medicine, The University of Alabama at Birmingham Birmingham, AL, USA
| | - Frederick Goldman
- Division of Hematology Oncology, Department of Pediatrics, The University of Alabama at Birmingham Birmingham, AL, USA
| | - Antonio Di Stasi
- Bone Marrow Transplantation and Cellular Therapy Unit, Division of Hematology-Oncology, Department of Medicine, The University of Alabama at Birmingham Birmingham, AL, USA
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14
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Yamazoe S, McQuade LE, Chen JK. Nitroreductase-activatable morpholino oligonucleotides for in vivo gene silencing. ACS Chem Biol 2014; 9:1985-90. [PMID: 25069083 PMCID: PMC4168795 DOI: 10.1021/cb500429u] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phosphorodiamidate morpholino oligonucleotides are widely used to interrogate gene function in whole organisms, and light-activatable derivatives can reveal spatial and temporal differences in gene activity. We describe here a new class of caged morpholino oligonucleotides that can be activated by the bacterial nitroreductase NfsB. We characterize the activation kinetics of these reagents in vitro and demonstrate their efficacy in zebrafish embryos that express NfsB either ubiquitously or in defined cell populations. In combination with transgenic organisms, such enzyme-actuated antisense tools will enable gene silencing in specific cell types, including tissues that are not amenable to optical targeting.
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Affiliation(s)
- Sayumi Yamazoe
- Departments
of Chemical and
Systems Biology and Developmental Biology, Stanford University School of Medicine, Stanford, California 94305 United States
| | - Lindsey E. McQuade
- Departments
of Chemical and
Systems Biology and Developmental Biology, Stanford University School of Medicine, Stanford, California 94305 United States
| | - James K. Chen
- Departments
of Chemical and
Systems Biology and Developmental Biology, Stanford University School of Medicine, Stanford, California 94305 United States
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15
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Abstract
Targeted cell ablation has proven to be a valuable approach to study in vivo cell functions during organogenesis, tissue homeostasis, and regeneration. Over the last two decades, various approaches have been developed to refine the control of cell ablation. In this review, we give an overview of the distinct genetic tools available for targeted cell ablation, with a particular emphasis on their respective specificity.
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Billerbeck E, de Jong Y, Dorner M, de la Fuente C, Ploss A. Animal models for hepatitis C. Curr Top Microbiol Immunol 2013; 369:49-86. [PMID: 23463197 DOI: 10.1007/978-3-642-27340-7_3] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Hepatitis C remains a global epidemic. Approximately 3 % of the world's population suffers from chronic hepatitis C, which is caused by hepatitis C virus (HCV)-a positive sense, single-stranded RNA virus of the Flaviviridae family. HCV has a high propensity for establishing a chronic infection. If untreated chronic HCV carriers can develop severe liver disease including fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). Antiviral treatment is only partially effective, costly, and poorly tolerated. A prophylactic or therapeutic vaccine for HCV does not exist. Mechanistic studies of virus-host interactions, HCV immunity, and pathogenesis as well as the development of more effective therapies have been hampered by the lack of a suitable small animal model. Besides humans, chimpanzees are the only species that is naturally susceptible to HCV infection. While experimentation in these large primates has yielded valuable insights, ethical considerations, limited availability, genetic heterogeneity, and cost limit their utility. In search for more tractable small animal models, numerous experimental approaches have been taken to recapitulate parts of the viral life cycle and/or aspects of viral pathogenesis that will be discussed in this review. Exciting new models and improvements in established models hold promise to further elucidate our understanding of chronic HCV infection.
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Affiliation(s)
- Eva Billerbeck
- Center for the Study of Hepatitis C, The Rockefeller University, NY, USA
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Li W, Xiang AP. Safeguarding clinical translation of pluripotent stem cells with suicide genes. Organogenesis 2013; 9:34-9. [PMID: 23511011 DOI: 10.4161/org.24317] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The generation of human induced pluripotent stem cells (hiPSCs) opens a new avenue in regenerative medicine. However, transplantation of hiPSC-derived cells carries a risk of tumor formation by residual pluripotent stem cells. Numerous adaptive strategies have been developed to prevent or minimize adverse events and control the in vivo behavior of transplanted stem cells and their progeny. Among them, the application of suicide gene modifications, which is conceptually similar to cancer gene therapy, is considered an ideal means to control wayward stem cell progeny in vivo. In this review, the choices of vectors, promoters, and genes for use in suicide gene approaches for improving the safety of hiPSCs-based cell therapy are introduced and possible new strategies for improvements are discussed. Safety-enhancing strategies that can selectively ablate undifferentiated cells without inducing virus infection or insertional mutations may greatly aid in translating human pluripotent stem cells into cell therapies in the future.
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Affiliation(s)
- Weiqiang Li
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, Guangdong P.R. China
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Hunt MA, Li D, Hay MP, Currie MJ, Robinson BA, Patterson AV, Dachs GU. Characterisation of enzyme prodrug gene therapy combinations in coated spheroids and vascular networks in vitro. J Gene Med 2012; 14:62-74. [DOI: 10.1002/jgm.1635] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Michelle A. Hunt
- Angiogenesis and Cancer Research Group, Department of Pathology; University of Otago; Christchurch; New Zealand
| | - Dan Li
- Auckland Cancer Society Research Centre; University of Auckland; Auckland; New Zealand
| | - Michael P. Hay
- Auckland Cancer Society Research Centre; University of Auckland; Auckland; New Zealand
| | - Margaret J. Currie
- Angiogenesis and Cancer Research Group, Department of Pathology; University of Otago; Christchurch; New Zealand
| | - Bridget A. Robinson
- Angiogenesis and Cancer Research Group, Department of Pathology; University of Otago; Christchurch; New Zealand
| | - Adam V. Patterson
- Auckland Cancer Society Research Centre; University of Auckland; Auckland; New Zealand
| | - Gabi U. Dachs
- Angiogenesis and Cancer Research Group, Department of Pathology; University of Otago; Christchurch; New Zealand
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Ouyang X, Chen JK. Synthetic strategies for studying embryonic development. ACTA ACUST UNITED AC 2010; 17:590-606. [PMID: 20609409 DOI: 10.1016/j.chembiol.2010.04.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 04/12/2010] [Accepted: 04/15/2010] [Indexed: 02/08/2023]
Abstract
Developmental biology has evolved from a descriptive science to one based on genetic principles and molecular mechanisms. Although molecular biology and genetic technologies have been the primary drivers of this transformation, synthetic strategies have been increasingly utilized to interrogate the mechanisms of embryonic patterning with spatial and temporal precision. In this review, we survey how chemical tools and engineered proteins have been used to perturb developmental processes at the DNA, RNA, protein, and cellular levels. We discuss the design principles, experimental capabilities, and limitations of each method, as well as future challenges for the chemical and developmental biology communities.
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Affiliation(s)
- Xiaohu Ouyang
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
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Dachs GU, Hunt MA, Syddall S, Singleton DC, Patterson AV. Bystander or no bystander for gene directed enzyme prodrug therapy. Molecules 2009; 14:4517-45. [PMID: 19924084 PMCID: PMC6255103 DOI: 10.3390/molecules14114517] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2009] [Revised: 11/03/2009] [Accepted: 11/05/2009] [Indexed: 12/12/2022] Open
Abstract
Gene directed enzyme prodrug therapy (GDEPT) of cancer aims to improve the selectivity of chemotherapy by gene transfer, thus enabling target cells to convert nontoxic prodrugs to cytotoxic drugs. A zone of cell kill around gene-modified cells due to transfer of toxic metabolites, known as the bystander effect, leads to tumour regression. Here we discuss the implications of either striving for a strong bystander effect to overcome poor gene transfer, or avoiding the bystander effect to reduce potential systemic effects, with the aid of three successful GDEPT systems. This review concentrates on bystander effects and drug development with regard to these enzyme prodrug combinations, namely herpes simplex virus thymidine kinase (HSV-TK) with ganciclovir (GCV), cytosine deaminase (CD) from bacteria or yeast with 5-fluorocytodine (5-FC), and bacterial nitroreductase (NfsB) with 5-(azaridin-1-yl)-2,4-dinitrobenzamide (CB1954), and their respective derivatives.
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Affiliation(s)
- Gabi U. Dachs
- Angiogenesis and Cancer Research Group, University of Otago, Christchurch, PO Box 4345, Christchurch 8140, New Zealand; E-Mail: (M.A.H.)
| | - Michelle A. Hunt
- Angiogenesis and Cancer Research Group, University of Otago, Christchurch, PO Box 4345, Christchurch 8140, New Zealand; E-Mail: (M.A.H.)
| | - Sophie Syddall
- Auckland Cancer Society Research Centre, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; E-Mails: (S.S.); (D-C.S.); (A-V.P.)
| | - Dean C. Singleton
- Auckland Cancer Society Research Centre, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; E-Mails: (S.S.); (D-C.S.); (A-V.P.)
| | - Adam V. Patterson
- Auckland Cancer Society Research Centre, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; E-Mails: (S.S.); (D-C.S.); (A-V.P.)
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Grohmann M, Paulmann N, Fleischhauer S, Vowinckel J, Priller J, Walther DJ. A mammalianized synthetic nitroreductase gene for high-level expression. BMC Cancer 2009; 9:301. [PMID: 19712451 PMCID: PMC3087338 DOI: 10.1186/1471-2407-9-301] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Accepted: 08/27/2009] [Indexed: 11/29/2022] Open
Abstract
Background The nitroreductase/5-(azaridin-1-yl)-2,4-dinitrobenzamide (NTR/CB1954) enzyme/prodrug system is considered as a promising candidate for anti-cancer strategies by gene-directed enzyme prodrug therapy (GDEPT) and has recently entered clinical trials. It requires the genetic modification of tumor cells to express the E. coli enzyme nitroreductase that bioactivates the prodrug CB1954 to a powerful cytotoxin. This metabolite causes apoptotic cell death by DNA interstrand crosslinking. Enhancing the enzymatic NTR activity for CB1954 should improve the therapeutical potential of this enzyme-prodrug combination in cancer gene therapy. Methods We performed de novo synthesis of the bacterial nitroreductase gene adapting codon usage to mammalian preferences. The synthetic gene was investigated for its expression efficacy and ability to sensitize mammalian cells to CB1954 using western blotting analysis and cytotoxicity assays. Results In our study, we detected cytoplasmic protein aggregates by expressing GFP-tagged NTR in COS-7 cells, suggesting an impaired translation by divergent codon usage between prokaryotes and eukaryotes. Therefore, we generated a synthetic variant of the nitroreductase gene, called ntro, adapted for high-level expression in mammalian cells. A total of 144 silent base substitutions were made within the bacterial ntr gene to change its codon usage to mammalian preferences. The codon-optimized ntro either tagged to gfp or c-myc showed higher expression levels in mammalian cell lines. Furthermore, the ntro rendered several cell lines ten times more sensitive to the prodrug CB1954 and also resulted in an improved bystander effect. Conclusion Our results show that codon optimization overcomes expression limitations of the bacterial ntr gene in mammalian cells, thereby improving the NTR/CB1954 system at translational level for cancer gene therapy in humans.
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Affiliation(s)
- Maik Grohmann
- Department of Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany.
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Abstract
Prodrug dependent cell ablation is a method that allows inducible and spatially restricted cell destruction. We describe transgenic methods to express the Escherichia coli nfsB in a tissue restricted manner in the zebrafish. This bacterial gene encodes a nitroreductase (NTR) enzyme that can render prodrugs such as metronidazole (Met) cytotoxic. Using the expression of NTR fused to a fluorescent protein, one can simultaneously make cells susceptible to prodrug treatment and visualize cell ablation as it occurs.
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Affiliation(s)
- Harshan Pisharath
- Department of Surgery, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
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Chu Y, Senghaas N, Köster RW, Wurst W, Kühn R. Novel caspase-suicide proteins for tamoxifen-inducible apoptosis. Genesis 2008; 46:530-6. [DOI: 10.1002/dvg.20426] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
Dendritic cells (DCs) play a central role in T-cell activation and the control of the inherent autoreactivity of the T-cell compartment. Pleiotropic DC functions are likely associated with discrete DC subsets. However, the latter remain largely defined by phenotype and unique anatomic location, rather than function. The investigation of DC involvement in complex phenomena that rely on multicellular interactions, such as immuno-stimulation and tolerization calls for an assessment of DC functions within physiological context. Given the highly dynamic DC compartment, the method of choice to study in vivo DC functions is their conditional ablation in the intact organism. Here, we summarize the recent progress in this field highlighting pitfalls and prospects of the approach.
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Kwak SP, Malberg JE, Howland DS, Cheng KY, Su J, She Y, Fennell M, Ghavami A. Ablation of central nervous system progenitor cells in transgenic rats using bacterial nitroreductase system. J Neurosci Res 2007; 85:1183-93. [PMID: 17304579 DOI: 10.1002/jnr.21223] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Specific ablation of central nervous system (CNS) progenitor cells in the brain of live animals is a powerful method to determine the functions of these cells and to reveal novel avenues for the treatment of several CNS-related disorders. To achieve this goal, we generated a line of transgenic rats expressing a bacterial enzyme, Escherichia coli nitroreductase gene (NTR), under control of the nestin promoter. In this system, NTR(+) cells are selectively eliminated upon application of prodrug CB1954, through activation of programmed cell death machineries. At 5 days of age, which is a time when cerebellar development is occurring, transgenic rats bearing the nestin-NTR/green fluorescent protein (GFP) gene are overtly normal and express NTR/GFP in neuronal stem cells, without any toxicity in these cells. The functional consequence of progenitor cell ablation was demonstrated by administering prodrug CB1954 into the cerebellum at this 5-day time point. Stem cell ablation in these neonates resulted in sensorimotor abnormalities, cerebellar degeneration, overall reduction in cerebellar seize, and manifestation of ataxia. In adult rats, GFP expression was not seen in the hippocampal progenitor cells and seen only at very low levels in the lateral ventricles, indicating a different NTR/GFP expression pattern between neonates and adults. In addition, application of CB1954 by intraventricular delivery reduced the number of 5-bromo-2'-deoxyuridine-labeled proliferating cells in the lateral ventricle but not hippocampus of NTR/GFP rats. These findings shows that targeted expression of NTR under a specific promoter might be of significant value in addressing the function of distinct cell population in vivo.
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Affiliation(s)
- Susan M Dymecki
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.
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27
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Yang CT, Hindes AE, Hultman KA, Johnson SL. Mutations in gfpt1 and skiv2l2 cause distinct stage-specific defects in larval melanocyte regeneration in zebrafish. PLoS Genet 2007; 3:e88. [PMID: 17542649 PMCID: PMC1885281 DOI: 10.1371/journal.pgen.0030088] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Accepted: 04/17/2007] [Indexed: 12/01/2022] Open
Abstract
The establishment of a single cell type regeneration paradigm in the zebrafish provides an opportunity to investigate the genetic mechanisms specific to regeneration processes. We previously demonstrated that regeneration melanocytes arise from cell division of the otherwise quiescent melanocyte precursors following larval melanocyte ablation with a small molecule, MoTP. The ease of ablating melanocytes by MoTP allows us to conduct a forward genetic screen for mechanisms specific to regeneration from such precursors or stem cells. Here, we reported the identification of two mutants, earthaj23e1 and juliej24e1 from a melanocyte ablation screen. Both mutants develop normal larval melanocytes, but upon melanocyte ablation, each mutation results in a distinct stage-specific defect in melanocyte regeneration. Positional cloning reveals that the earthaj23e1 mutation is a nonsense mutation in gfpt1 (glutamine:fructose-6-phosphate aminotransferase 1), the rate-limiting enzyme in glucosamine-6-phosphate biosynthesis. Our analyses reveal that a mutation in gfpt1 specifically affects melanocyte differentiation (marked by melanin production) at a late stage during regeneration and that gfpt1 acts cell autonomously in melanocytes to promote ontogenetic melanocyte darkening. We identified that the juliej24e1 mutation is a splice-site mutation in skiv2l2 (superkiller viralicidic activity 2-like 2), a predicted DEAD-box RNA helicase. Our in situ analysis reveals that the mutation in skiv2l2 causes defects in cell proliferation, suggesting that skiv2l2 plays a role in regulating melanoblast proliferation during early stages of melanocyte regeneration. This finding is consistent with previously described role for cell division during larval melanocyte regeneration. The analyses of these mutants reveal their stage-specific roles in melanocyte regeneration. Interestingly, these mutants identify regeneration-specific functions not only in early stages of the regeneration process, but also in late stages of differentiation of the regenerating melanocyte. We suggest that mechanisms of regeneration identified in this mutant screen may reveal fundamental differences between the mechanisms that establish differentiated cells during embryogenesis, and those involved in larval or adult growth. Programs of ontogenetic development and regeneration share many components. Differences in genetic requirements between regeneration and development may identify mechanisms specific to the stem cells that maintain cell populations in postembryonic stages, or identify other regeneration-specific functions. Here, we utilize a forward genetic approach that takes advantage of single cell type ablation and regeneration to isolate mechanisms specific to regeneration of the zebrafish melanocyte. Upon chemical ablation of melanocytes, zebrafish larvae reconstitute their larval pigment pattern from undifferentiated precursors or stem cells. We isolated two zebrafish mutants that develop embryonic melanocytes normally but fail to regenerate their melanocytes upon ablation. This phenotype suggests the regeneration-specific roles of the mutated genes. We further identified the mutations in gfpt1 and skiv2l2 and show their stage-specific roles in melanocyte regeneration. Interestingly, these mutants identify regeneration-specific functions not only in early stages of the regeneration process (skiv2l2), but also in late stages of differentiation of the regenerating melanocyte (gfpt1). We suggest that mechanisms of regeneration identified in this mutant screen may reveal fundamental differences between the mechanisms that establish differentiated cells during embryogenesis and those involved in larval or adult growth.
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Affiliation(s)
- Chao-Tsung Yang
- Department of Genetics, Washington University School of Medicine, Saint Louis, Missouri, United States
| | - Anna E Hindes
- Department of Genetics, Washington University School of Medicine, Saint Louis, Missouri, United States
| | - Keith A Hultman
- Department of Genetics, Washington University School of Medicine, Saint Louis, Missouri, United States
| | - Stephen L Johnson
- Department of Genetics, Washington University School of Medicine, Saint Louis, Missouri, United States
- * To whom correspondence should be addressed. E-mail:
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Pisharath H, Rhee JM, Swanson MA, Leach SD, Parsons MJ. Targeted ablation of beta cells in the embryonic zebrafish pancreas using E. coli nitroreductase. Mech Dev 2006; 124:218-29. [PMID: 17223324 PMCID: PMC2583263 DOI: 10.1016/j.mod.2006.11.005] [Citation(s) in RCA: 286] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2006] [Revised: 11/26/2006] [Accepted: 11/30/2006] [Indexed: 11/16/2022]
Abstract
In order to generate a zebrafish model of beta cell regeneration, we have expressed an Escherichia coli gene called nfsB in the beta cells of embryonic zebrafish. This bacterial gene encodes a nitroreductase (NTR) enzyme, which can convert prodrugs such as metronidazole (Met) to cytotoxins. By fusing nfsB to mCherry, we can simultaneously render beta cells susceptible to prodrug and visualize Met dependent cell ablation. We show that the neighboring alpha and delta cells are unaffected by prodrug treatment and that ablation is beta cell specific. Following drug removal and 36h of recovery, beta cells regenerate. Using ptf1a morphants, it is clear that this beta cell recovery occurs independently of the presence of the exocrine pancreas. Also, by using photoconvertible Kaede to cell lineage trace and BrdU incorporation to label proliferation, we investigate mechanisms for beta regeneration. Therefore, we have developed a unique resource for the study of beta cell regeneration in a living vertebrate organism, which will provide the opportunity to conduct large-scale screens for pharmacological and genetic modifiers of beta cell regeneration.
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Affiliation(s)
- Harshan Pisharath
- Department of Comparative Medicine, Johns Hopkins School of Medicine, Baltimore, MD 21205, U.S.A
| | - Jerry M. Rhee
- Department of Surgery, Johns Hopkins School of Medicine, Baltimore, MD 21205, U.S.A
| | - Michelle A. Swanson
- Department of Surgery, Johns Hopkins School of Medicine, Baltimore, MD 21205, U.S.A
| | - Steven D. Leach
- Department of Surgery, Johns Hopkins School of Medicine, Baltimore, MD 21205, U.S.A
- Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, MD 21205, U.S.A
| | - Michael J. Parsons
- Department of Surgery, Johns Hopkins School of Medicine, Baltimore, MD 21205, U.S.A
- #corresponding author , 720 Rutland Avenue, Ross 771, Baltimore, MD 21205, phone 410 502 2982, Fax 410 614 2913
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Sato M, Tanigawa M. Production of CETD transgenic mouse line allowing ablation of any type of specific cell population. Mol Reprod Dev 2005; 72:54-67. [PMID: 15902717 DOI: 10.1002/mrd.20323] [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] [Indexed: 11/10/2022]
Abstract
Diphtheria toxin A-chain (DT-A) is a potent inhibitor of protein synthesis. As little as a single molecule of DT-A can result in cell death. DT-A gene driven by a tissue-specific promoter is used to achieve genetic ablation of a particular cell lineage. However, this transgenic approach often results in aberrant depletion of unrelated cells. To avoid this, we established a method for specific depletion of a cell population by controlled expression of the DT-A gene via the Cre-loxP system. We produced five transgenic mice carrying CETD construct containing loxP-flanked enhanced green fluorescent protein (EGFP) cDNA and the DT-A gene. Transfection of primary cultured cells derived from CETD transgenic fetus with Cre expression plasmid resulted in extensive cell loss, as expected. Bigenic (double transgenic) offspring obtained by crossbreeding between CETD and MNCE transgenic mice in which Cre expression is controlled by the myelin basic protein (MBP) promoter exhibited embryonic lethality, suggesting expression of Cre at embryonic stages. Intravenous injection of Cre expression vector to CETD mice led to generation of glomerular lesions, probably due to predominant depletion of glomerular epithelial cells. This Cre-loxP-based cell ablation technology is powerful and convenient method of generating mice lacking any chosen cell population.
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Affiliation(s)
- Masahiro Sato
- The Institute of Medical Sciences, Tokai University, Bohseidai, Isehara, Kanagawa, Japan.
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Buch T, Heppner FL, Tertilt C, Heinen TJAJ, Kremer M, Wunderlich FT, Jung S, Waisman A. A Cre-inducible diphtheria toxin receptor mediates cell lineage ablation after toxin administration. Nat Methods 2005; 2:419-26. [PMID: 15908920 DOI: 10.1038/nmeth762] [Citation(s) in RCA: 662] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2004] [Accepted: 04/18/2005] [Indexed: 12/12/2022]
Abstract
A new system for lineage ablation is based on transgenic expression of a diphtheria toxin receptor (DTR) in mouse cells and application of diphtheria toxin (DT). To streamline this approach, we generated Cre-inducible DTR transgenic mice (iDTR) in which Cre-mediated excision of a STOP cassette renders cells sensitive to DT. We tested the iDTR strain by crossing to the T cell- and B cell-specific CD4-Cre and CD19-Cre strains, respectively, and observed efficient ablation of T and B cells after exposure to DT. In MOGi-Cre/iDTR double transgenic mice expressing Cre recombinase in oligodendrocytes, we observed myelin loss after intraperitoneal DT injections. Thus, DT crosses the blood-brain barrier and promotes cell ablation in the central nervous system. Notably, we show that the developing DT-specific antibody response is weak and not neutralizing, and thus does not impede the efficacy of DT. Our results validate the use of iDTR mice as a tool for cell ablation in vivo.
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Affiliation(s)
- Thorsten Buch
- Laboratory for Molecular Immunology, Institute for Genetics, University of Cologne, D-50931 Cologne, Germany.
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Dachs GU, Tupper J, Tozer GM. From bench to bedside for gene-directed enzyme prodrug therapy of cancer. Anticancer Drugs 2005; 16:349-59. [PMID: 15746571 DOI: 10.1097/00001813-200504000-00001] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Gene therapy of cancer offers the possibility of a targeted treatment that destroys tumors and metastases, but not normal tissues. In gene-directed enzyme prodrug therapy (GDEPT), or suicide gene therapy, the gene encoding an enzyme is delivered to tumor cells, followed by administration of a prodrug, which is converted locally to a cytotoxin by the enzyme. The producer cells as well as surrounding bystanders are subsequently killed. Promising results have meant that suicide gene therapy has reached multicenter phase III clinical trials. This review will discuss the development, efficiency, mode of action and pharmacokinetics of seven GDEPT systems in vitro and in vivo. We will review the latest data of those systems in clinical trials (herpes simplex virus thymidine kinase/gancyclovir, bacterial cytosine deaminase/5-fluorocytosine, bacterial nitroreductase/CB1954 and cytochrome P450/cyclophosphamide), as well as the development of more recent and experimental systems which are not yet in clinical trials (P450 reductase/tirapazamine, carboxypeptidase/CMDA, horseradish peroxidase/indole-3-acetic acid or paracetamol and others).
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Affiliation(s)
- Gabi U Dachs
- Angiogenesis Research Group, Department of Pathology, Christchurch School of Medicine and Health Sciences, University of Otago, Christchurch, New Zealand.
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Helsby NA, Atwell GJ, Yang S, Palmer BD, Anderson RF, Pullen SM, Ferry DM, Hogg A, Wilson WR, Denny WA. Aziridinyldinitrobenzamides: Synthesis and Structure−Activity Relationships for Activation by E. coli Nitroreductase. J Med Chem 2004; 47:3295-307. [PMID: 15163209 DOI: 10.1021/jm0498699] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The 5-aziridinyl-2,4-dinitrobenzamide CB 1954 is a substrate for the oxygen-insensitive nitroreductase (NTR) from E. coli and is in clinical trial in combination with NTR-armed adenoviral vectors in a GDEPT protocol; CB 1954 is also of interest for selective deletion of NTR-marked cells in normal tissues. Since little further drug development has been carried out around this lead, we report here the synthesis of more soluble variants and regioisomers and structure-activity relationship (SAR) studies. The compounds were primarily prepared from the corresponding chloro(di)nitroacids through amide side chain elaboration and subsequent aziridine formation. One-electron reduction potentials [E(1)], determined by pulse radiolysis, were around -400 mV, varying little for aziridinyldinitrobenzamide regioisomers. Cytotoxicity in a panel of NTR-transfected cell lines showed that in the CB 1954 series there was considerable tolerance of substituted CONHR side chains. The isomeric 2-aziridinyl-3,5-dinitrobenzamide was also selective toward NTR+ve lines but was approximately 10-fold less potent than CB 1954. Other regioisomers were too insoluble to evaluate. While CB 1954 gave both 2- and 4-hydroxylamine metabolites in NTR+ve cells, related analogues with substituted carboxamides gave only a single hydroxylamine metabolite possibly because the steric bulk in the side chain constrains binding within the active site. CB 1954 is also a substrate for the two-electron reductase DT-diaphorase, but all of the other aziridines (regioisomers and close analogues) were poorer substrates with resulting improved specificity for NTR. Bystander effects were determined in multicellular layer cocultures and showed that the more hydrophilic side chains resulted in a modest reduction in bystander killing efficiency. A limited number of analogues were tested for in vivo activity, using a single ip dose to CD-1 nude mice bearing WiDr-NTR(neo) tumors. The most active of the CB 1954 analogues was a diol derivative, which showed a substantial median tumor growth delay (59 days compared with >85 days for CB 1954) in WiDr xenografts comprising 50% NTR+ve cells. The diol is much more soluble and can be formulated in saline for administration. The results suggest there may be advantages with carefully selected analogues of CB 1954; the weaker bystander effect of its diol derivative may be an advantage in the selective cell ablation of NTR-tagged cells in normal tissues.
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Affiliation(s)
- Nuala A Helsby
- Auckland Cancer Society Research Centre, School of Medical Sciences, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand.
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Verdijk RM, Wilke M, Beslier V, Kloosterman A, Brand A, Goulmy E, Mutis T. Escherichia coli-nitroreductase suicide gene control of human telomerase reverse transcriptase-transduced minor histocompatibility antigen-specific cytotoxic T cells. Bone Marrow Transplant 2004; 33:963-7. [PMID: 15048139 DOI: 10.1038/sj.bmt.1704470] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Adoptive immunotherapy with ex vivo generated cytotoxic T lymphocytes (CTLs) is applied for the treatment of leukemia relapses or viral infections after allogeneic stem cell transplantation. A common problem of adoptive immunotherapy strategies is the ex vivo expansion of the generated T cells to sufficient numbers. CTLs can be efficiently expanded by ectopic expression of the human telomerase gene (hTert). However, hTert transduction may also increase the chance for malignant transformation. Therefore, we explored the feasibility of suicide gene control of ex vivo generated CTLs expanded through the ectopic expression of hTert. To this end, we compared the efficacy of the new Escherichia coli-nitroreductase (E. coli-Ntr) suicide gene with the well-known herpes simplex virus-thymidine kinase (HSV-Tk). Introduction of hTert provided the transduced CTLs with a distinct growth advantage over the nontransduced CTLs. The hTert-E. coli-Ntr double-transduced CTLs retained their antigen-specific functions. Treatment of hTert-E. coli-Ntr double-transduced CTLs with metronidazole significantly inhibited the proliferation to a similar extent to the treatment of hTert-HSV-Tk double-transduced CTLs with ganciclovir. This is the first application of the E. coli-nitroreductase gene for the elimination of human T cells with metronidazole.
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Affiliation(s)
- R M Verdijk
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands
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35
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Gusterson BA, Cui W, Clark AJ. Development of novel selective cell ablation in the mammary gland and brain to study cell-cell interactions and chemoprevention. Recent Results Cancer Res 2003; 163:31-45; discussion 264-6. [PMID: 12903841 DOI: 10.1007/978-3-642-55647-0_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We have generated transgenic mice which express the gene encoding Escherichia coli nitroreductase (NTR) specifically in the luminal epithelial cells of the mammary gland and the glial cells of the brain. The enzyme activates an antitumour drug CB 1954, to produce a cross-linking agent that kills all cells expressing the enzyme. We have shown that administration of the antitumour drug CB 1954 rapidly and selectively kills these cells. Original experiments demonstrated the ability to ablate the luminal cells in the mammary gland with no apparent bystander effect. Subsequently, astrocytes expressing nitroreductase under the targeting of the GFAP promoter were selectively ablated following administration of the prodrug CB 1954 produces a degeneration of granular neurones due to changes in glutamate levels. Recent experiments demonstrated inhibition of myc-dependent mammary tumours using the same enzyme (nitroreductase)-prodrug (CB 1954), combination. Owing to the ease of control of NTR-mediated cell ablation, we anticipate that this system will supersede herpes simplex virus type 1 thymidine kinase. There are widespread potential applications for this approach in the dissection of complex cellular interactions during development and in the adult organism. The present transgenic models also have important applications for the study in vivo of novel prodrugs that can be selected for variable degrees of bystander effects. Such studies will have particular significance for those groups advocating the use of NTR as an appropriate enzyme for gene-directed enzyme prodrug therapy by providing models of a wide range of human disease for mechanistic and therapeutic experimentation. The results clearly demonstrate that the model has potential to study chemoprevention and fundamental questions on cell-cell interactions in cell biology.
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36
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Green NK, McNeish IA, Doshi R, Searle PF, Kerr DJ, Young LS. Immune enhancement of nitroreductase-induced cytotoxicity: studies using a bicistronic adenovirus vector. Int J Cancer 2003; 104:104-12. [PMID: 12532426 DOI: 10.1002/ijc.10916] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The nitroreductase (NR)/CB1954 enzyme prodrug system has given promising results in preclinical studies and is currently being assessed in phase I clinical trials. It is well established that there is an immune component to the bystander effect observed with other systems such as thymidine kinase and cytosine deaminase; however, such an effect has not previously been described using NR. We have preliminary data suggesting an immune bystander effect with NR to further examine these effects and their potential enhancement by cytokines, an adenoviral vector containing CMV-NR, an internal ribosome entry site (IRES) and the gene for murine GM-CSF (mGM-CSF) was constructed. The NR-GM-CSF virus was validated in 2 experimental models and demonstrated increased therapeutic efficacy in the MC26 murine colorectal tumour model. These data illustrate that the combination of suicide gene therapy using NR and CB1954 with immune stimulation via GM-CSF gives an improved response compared to either modality alone and suggests that the immune component of this response may be beneficial in combating unresectable, metastatic disease and preventing tumour recurrence.
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MESH Headings
- Adenocarcinoma/genetics
- Adenocarcinoma/immunology
- Adenocarcinoma/therapy
- Adenoviruses, Human/genetics
- Adjuvants, Immunologic/therapeutic use
- Animals
- Antineoplastic Agents, Alkylating/pharmacokinetics
- Antineoplastic Agents, Alkylating/therapeutic use
- Aziridines/pharmacokinetics
- Aziridines/pharmacology
- Aziridines/therapeutic use
- Bystander Effect
- Colorectal Neoplasms/genetics
- Colorectal Neoplasms/immunology
- Colorectal Neoplasms/therapy
- Combined Modality Therapy
- Cytomegalovirus/genetics
- Defective Viruses/genetics
- Drug Resistance, Neoplasm/genetics
- Escherichia coli Proteins/genetics
- Escherichia coli Proteins/metabolism
- Female
- Genes
- Genes, Synthetic
- Genetic Therapy
- Genetic Vectors/genetics
- Genetic Vectors/therapeutic use
- Granulocyte-Macrophage Colony-Stimulating Factor/genetics
- Granulocyte-Macrophage Colony-Stimulating Factor/therapeutic use
- Humans
- Immunotherapy
- Mesothelioma/enzymology
- Mesothelioma/pathology
- Mice
- Mice, Inbred BALB C
- Neoplasm Transplantation
- Nitroreductases/genetics
- Nitroreductases/metabolism
- Prodrugs/pharmacokinetics
- Prodrugs/pharmacology
- Prodrugs/therapeutic use
- Specific Pathogen-Free Organisms
- Tumor Cells, Cultured/drug effects
- Tumor Cells, Cultured/transplantation
- Tumor Cells, Cultured/virology
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Affiliation(s)
- Nicola K Green
- Department of Clinical Pharmacology, University of Oxford, Radcliffe Infirmary, Oxford, United Kingdom.
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37
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Sivaraman L, Gay J, Hilsenbeck SG, Shine HD, Conneely OM, Medina D, O'Malley BW. Effect of selective ablation of proliferating mammary epithelial cells on MNU induced rat mammary tumorigenesis. Breast Cancer Res Treat 2002; 73:75-83. [PMID: 12083633 DOI: 10.1023/a:1015227719105] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Proliferating cells within the terminal end buds of the virgin female rat mammary gland are the most susceptible to chemical carcinogen induced tumorigenesis. We hypothesized that selective ablation of proliferating cells in the mammary gland would reduce mammary tumor incidence upon carcinogen challenge. Selective ablation of proliferating cells was achieved by intraductal injections of Adv-RSV-tk and gancyclovir administration. Despite efficient viral transduction of the thymidine kinase protein and the apparent elimination of >90% of the proliferating cells, the rats exhibited a higher incidence of MNU induced mammary tumors arising with shorter latency as compared to control animals. Several possible explanations of the puzzling relationship between elimination of cycling cells and increased tumor incidence are discussed and alternative strategies for the prevention of breast cancer are proposed.
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MESH Headings
- 9,10-Dimethyl-1,2-benzanthracene/toxicity
- Adenoviridae/genetics
- Animals
- Antiviral Agents/pharmacology
- Carcinogens/toxicity
- Cell Division/drug effects
- Cell Division/genetics
- Cell Transformation, Neoplastic
- Disease Models, Animal
- Female
- Ganciclovir/pharmacology
- Gene Expression Regulation, Developmental
- Immunoenzyme Techniques
- Incidence
- Injections, Intralesional
- Mammary Glands, Animal/cytology
- Mammary Glands, Animal/growth & development
- Mammary Neoplasms, Experimental/chemically induced
- Mammary Neoplasms, Experimental/enzymology
- Mammary Neoplasms, Experimental/epidemiology
- Methylnitrosourea/toxicity
- Rats
- Rats, Inbred WF
- Thymidine Kinase/genetics
- Thymidine Kinase/metabolism
- beta-Galactosidase/metabolism
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Affiliation(s)
- Lakshmi Sivaraman
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
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38
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Shibata T, Giaccia AJ, Brown JM. Hypoxia-inducible regulation of a prodrug-activating enzyme for tumor-specific gene therapy. Neoplasia 2002; 4:40-8. [PMID: 11922390 PMCID: PMC1503309 DOI: 10.1038/sj.neo.7900189] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2001] [Indexed: 11/09/2022]
Abstract
Previous studies have suggested that tumor hypoxia could be exploited for cancer gene therapy. Using hypoxia-responsive elements derived from the human vascular endothelial growth factor gene, we have generated vectors expressing a bacterial nitroreductase (NTR) gene that can activate the anticancer prodrug CB1954. Stable transfectants of human HT1080 tumor cells with hypoxia-inducible vectors were established with G418 selection. Hypoxic induction of NTR protein correlated with increased sensitivity to in vitro exposure of HT1080 cells to the prodrug. Growth delay assays were performed with established tumor xenografts derived from the same cells to detect the in vivo efficacy of CB1954 conversion to its cytotoxic form. Significant antitumor effects were achieved with intraperitoneal injections of CB1954 both in tumors that express NTR constitutively or with a hypoxia-inducible promoter. In addition, respiration of 10% 02 increased tumor hypoxia in vivo and enhanced the antitumor effects. Taken together, these results demonstrate that hypoxia-inducible vectors may be useful for tumor-selective gene therapy, although the problem of delivery of the vector to the tumors, particularly to the hypoxic cells in the tumors, is not addressed by these studies.
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Affiliation(s)
- Toru Shibata
- Department of Radiation Oncology, Stanford University School of Medicine, CA 94305-5152, USA
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39
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Anlezark GM, Vaughan T, Fashola-Stone E, Paul Michael N, Murdoch H, Sims MA, Stubbs S, Wigley S, Minton NP. Bacillus amyloliquefaciens orthologue of Bacillus subtilis ywrO encodes a nitroreductase enzyme which activates the prodrug CB 1954. MICROBIOLOGY (READING, ENGLAND) 2002; 148:297-306. [PMID: 11782522 DOI: 10.1099/00221287-148-1-297] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A nitroreductase with distinct properties that can activate the prodrug 5-aziridinyl-2,4-dinitrobenzamide (CB 1954) was isolated from Bacillus amyloliquefaciens. The encoding gene was identified as a homologue of the ywrO of Bacillus subtilis, and was obtained as a PCR product by reverse genetics, cloned and the entire nucleotide sequence determined. The gene was found to reside between homologues of the B. subtilis alsD and yswB genes; however, the ywrO and yswB genes of B. amyloliquefaciens were not separated by a fourth gene, ywsA. The B. amyloliquefaciens ywrO gene was overexpressed, the recombinant protein purified and its properties were compared with those of two CB 1954-activating enzymes, Escherichia coli B nitroreductase (NTR) and Walker DT-diaphorase (DTD). In common with these enzymes menadione was an electron acceptor (K(m) 3 microM) and activity with this substrate was inhibited by the presence of dicoumarol (K(i) 1.0 microM). In contrast, YwrO showed a marked preference for NADPH as a cofactor (K(m) 40 microM) and therefore could not be classified as a DTD (EC 1.6.99.2). The flavin FMN was an acceptor with high affinity. B. amyloliquefaciens YwrO was shown to be a flavoprotein with a monomeric molecular mass of 21.5 kDa by calculation and SDS-PAGE. The cytotoxic 4-hydroxylamine derivative was the single CB 1954 reduction product, but B. amyloliquefaciens YwrO was inactive with the bischloroethyl analogue of CB 1954, SN 23862. In both of these properties B. amyloliquefaciens YwrO more closely resembles DTD than NTR. Its K(m) for CB 1954 was lower than that of NTR (617 microM compared to 862 microM). Enhanced in vitro cytotoxicity of CB 1954 was demonstrated on incubation of V79 cells with prodrug, NADPH and B. amyloliquefaciens YwrO. The work has led to the identification of a previously unknown nitroreductase, B. amyloliquefaciens YwrO, with distinct properties which will aid the rational selection of appropriate genes for applications in directed enzyme prodrug therapy (DEPT).
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Affiliation(s)
- Gill M Anlezark
- Centre for Applied Microbiology and Research (CAMR), Porton Down, Salisbury, Wiltshire SP4 0JG, UK1
| | - Thomas Vaughan
- Centre for Applied Microbiology and Research (CAMR), Porton Down, Salisbury, Wiltshire SP4 0JG, UK1
| | - Elizabeth Fashola-Stone
- Centre for Applied Microbiology and Research (CAMR), Porton Down, Salisbury, Wiltshire SP4 0JG, UK1
| | - N Paul Michael
- Centre for Applied Microbiology and Research (CAMR), Porton Down, Salisbury, Wiltshire SP4 0JG, UK1
| | - Heather Murdoch
- Centre for Applied Microbiology and Research (CAMR), Porton Down, Salisbury, Wiltshire SP4 0JG, UK1
| | - Meg A Sims
- Centre for Applied Microbiology and Research (CAMR), Porton Down, Salisbury, Wiltshire SP4 0JG, UK1
| | - Simon Stubbs
- Centre for Applied Microbiology and Research (CAMR), Porton Down, Salisbury, Wiltshire SP4 0JG, UK1
| | - Stuart Wigley
- Centre for Applied Microbiology and Research (CAMR), Porton Down, Salisbury, Wiltshire SP4 0JG, UK1
| | - Nigel P Minton
- Centre for Applied Microbiology and Research (CAMR), Porton Down, Salisbury, Wiltshire SP4 0JG, UK1
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40
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Cui W, Gusterson BA, Clark AJ. Inhibition of myc-dependent breast tumor formation in transgenic mice. Breast Cancer Res Treat 2002; 71:9-20. [PMID: 11859878 DOI: 10.1023/a:1013334013065] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
One of the most promising approaches for cancer gene therapy is the use of the so-called suicide genes, which encode prodrug-activating enzymes and render transduced cells more sensitive to prodrugs. The enzyme nitroreductase (NTR) converts prodrug CB1954 into a cytotoxic DNA interstrand cross-linking agent. We have established transgenic mice in which the pro-oncogene c-myc and NTR were fused to the internal ribosome entry site and coexpressed in luminal cells of the mammary gland under the control of mouse whey acidic protein (WAP) promoter to evaluate NTR mediated ablation of mammary tumors. More than 78% of transgenic females developed in situ or infiltrating carcinomas after three to four pregnancies. By contrast, if the transgenic female mice were given the prodrug CB1954 during their third lactation, the incidence of tumors decreased to less than 40% (P < 0.05). The total number of carcinomas was even more striking with 117 carcinomas identified in 14 non-ablated transgenics compared with only five in 15 treated animals (p < 0.05, student t test). C-myc induced pleomorphic nuclei and mitotic figures were seen as a field change in over 70% of the untreated transgenics compared to 20% in the treated group. Our results suggest that the enzyme pro-drug system NTR-CB1954 efficiently inhibit myc-dependent tumor formation and malignant progression in the mammary gland.
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Affiliation(s)
- Wei Cui
- Department of Gene Expression & Development, Roslin Institute, Midlothian, UK
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41
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Orian JM, Ahern AJ, Ayers MM, Levine JM, Tapp LD, Reynolds R. Disturbed oligodendrocyte development and recovery from hypomyelination in a c-myc transgenic mouse mutant. J Neurosci Res 2001; 66:46-58. [PMID: 11599001 DOI: 10.1002/jnr.1196] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The complexity of interactions underlying the elaboration of myelin has been extensively demonstrated. We provide evidence that signals promoting myelination are not confined to the normal developmental time window for myelination and persist well into adult life. The 2-50 mutant, described previously, carries a c-myc transgene regulated by a myelin basic protein promoter. This mutant is characterised by severe hypomyelination and abnormal oligodendrocytes in early life, followed by loss of the phenotype and normal longevity. We show that c-myc expression in early oligodendrocyte development results in a substantial reduction of cells of this lineage. However, apparent complete recovery, associated with loss of c-myc expression, axonal survival, and gradual myelin accumulation, is observed by 4 months of age. Thus, stimulation of myelination continues during adult life until normal myelin levels are established. We propose that this mutant may contribute to the characterisation of oligodendrocyte responses to myelinating signals.
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Affiliation(s)
- J M Orian
- Department of Neuroinflammation, Imperial College School of Medicine, Charing Cross Campus, London, United Kingdom.
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42
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Blackwood L, O'Shaughnessy PJ, Reid SW, Argyle DJ. E. coli nitroreductase/CB1954: in vitro studies into a potential system for feline cancer gene therapy. Vet J 2001; 161:269-79. [PMID: 11352484 DOI: 10.1053/tvjl.2000.0557] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Investigations were carried out to identify a suitable prodrug activating system for feline gene therapy with the eventual aim of treating feline thyroid disease and feline neoplasia. The E. coli nitroreductase (NTR)/CB1954 prodrug activating system was evaluated in vitro in feline cells by transient transfection with a nitroreductase expressing construct and subsequent treatment with the prodrug CB1954. The feline cells successfully expressed E. coli nitroreductase, which was able to activate the prodrug CB1954 resulting in cytotoxicity to both transformed and adjacent cells (a bystander effect) in vitro. In the absence of nitroreductase, CB1954 was non-toxic to feline cells. In addition, the nitroreductase gene was expressed in rat thyroid cells under the control of the cell type specific feline thyroglobulin promoter. This paper demonstrates that the E. coli nitroreductase/CB1954 system may be suitable for in vivo feline gene therapy, and further investigations are warranted.
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Affiliation(s)
- L Blackwood
- Molecular Therapeutics Research Group, Small Animal Clinical Studies , Glawgow, UK.
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43
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Spooner RA, Maycroft KA, Paterson H, Friedlos F, Springer CJ, Marais R. Appropriate subcellular localisation of prodrug-activating enzymes has important consequences for suicide gene therapy. Int J Cancer 2001; 93:123-30. [PMID: 11391631 DOI: 10.1002/ijc.1288] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Escherichia coli B nitroreductase (NR) has been expressed stably in MDA-MB-361 human breast adenocarcinoma cells either as the wild-type protein (wtNR), which is distributed evenly between the cytoplasmic and nuclear compartments, or targeted to the mitochondrion (mtNR). Whereas bacterial NR is active as a dimer, a proportion of wtNR is monomeric. In contrast, mtNR is mostly dimeric, suggesting that it adopts a more stable, native conformation. Despite this, when tested in gene-directed enzyme prodrug therapy cell cytotoxicity studies, cells expressing wtNR or mtNR had similar sensitivity to the prodrug CB1954 and mounted similar bystander killing effects. Furthermore, when short prodrug exposures were given, wtNR was more efficient at killing cells than mtNR. These data demonstrate that the site of enzyme expression and prodrug activation is an important variable that requires consideration in suicide gene therapy approaches.
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Affiliation(s)
- R A Spooner
- CRC Centre for Cancer Therapeutics, Institute of Cancer Research, Sutton, United Kingdom
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44
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Isles AR, Ma D, Milsom C, Skynner MJ, Cui W, Clark J, Keverne EB, Allen ND. Conditional ablation of neurones in transgenic mice. JOURNAL OF NEUROBIOLOGY 2001; 47:183-93. [PMID: 11333400 DOI: 10.1002/neu.1026] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Conditional targeted ablation of specific cell populations in living transgenic animals is a very powerful strategy to determine cell functions in vivo. This approach would be of particular value to study the functions of distinct neuronal populations; however, the transgene of choice for conditional cell ablation studies in mice, the herpes simplex virus thymidine kinase gene, cannot be used to ablate neurones as its principal mode of action relies on cell proliferation. Here we report that expression of the E.coli nitroreductase gene (Ntr) and metabolism of the prodrug CB1954 (5-aziridin-1-yl-2-4-dinitrobenzamide) to its cytotoxic derivative can be used to conditionally and acutely ablate specific neuronal populations in vivo. As proof of principal, we have ablated olfactory and vomeronasal receptor neurones by expressing Ntr under the control of the olfactory marker protein (OMP) gene promoter. We demonstrate that following CB1954 administration, olfactory and vomeronasal receptor neurones expressing the transgene were selectively eliminated from the olfactory epithelium (OE), and projections to the olfactory bulb (OB) were lost. The functional efficacy of cell ablation was demonstrated using a highly sensitive behavioural test to show that ablated mice had lost the olfactory ability to discriminate distinct odors and were consequently rendered anosmic. Targeted expression of Ntr to specific neuronal populations using conventional transgenes, as described here, or by "knock-in" gene targeting using embryonic stem cells may be of significant value to address the functions of distinct neuronal populations in vivo.
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Affiliation(s)
- A R Isles
- Laboratory of Cognitive and Developmental Neuroscience, Neurobiology Programme, The Babraham Institute, Babraham, Cambridge, CB2 4AT, United Kingdom
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45
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Abstract
Gene therapy of cancer is a novel approach with the potential to selectively eradicate tumour cells, whilst sparing normal tissue from damage. In particular, gene-directed enzyme prodrug therapy (GDEPT) is based on the delivery of a gene that encodes an enzyme which is non-toxic per se, but is able to convert a prodrug into a potent cytotoxin. Several GDEPT systems have been investigated so far, demonstrating effectiveness in both tissue culture and animal models. Based on these encouraging results, phase I/II clinical trials have been performed and are still ongoing. The aim of this review is to summarise the progress made in the design and application of GDEPT strategies. The most widely used enzyme/prodrug combinations already in clinical trials (e.g., herpes simplex 1 virus thymidine kinase/ganciclovir and cytosine deaminase/5-fluorocytosine), as well as novel approaches (carboxypeptidase G2/CMDA, horseradish peroxidase/indole-3-acetic acid) are described, with a particular attention to translational research and early clinical results.
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Affiliation(s)
- O Greco
- Tumour Microcirculation Group, Gray Laboratory Cancer Research Trust, Mount-Verion Hospital, Northwood, Middlesex, UK
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46
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Abstract
The feline thyroglobulin promoter was identified by a combination of standard polymerase chain reaction (PCR) techniques, using primers designed according to regions of homology in published sequences from other species, then adaptor ligated PCR. A 310 bp fragment of the feline thyroglobulin promoter was generated, including 8 nucleotides of adaptor sequence at the 5' end and, based on the putative transcription start site, 36 nucleotides of the thyroglobulin mRNA (untranslated portion). The homology between the feline promoter sequence (from 193 bp upstream to the putative cap site) and canine, bovine and human sequences was 89%, 81% and 78%, respectively. Transient transfection studies, using reporter constructs in which the feline promoter controlled expression of chloramphenicol acetyl transferase, demonstrated promoter activity in thyroid cells, but no activity in non-thyroid cells. The data presented here demonstrate that the feline thyroglobulin promoter may provide a targeting mechanism for somatic gene therapy of feline thyroid disease.
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Affiliation(s)
- L Blackwood
- Molecular Therapeutics Research Group, Division of Small Animal Clinical Studies, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, G61 1QH, Glasgow, UK.
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47
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Lakhani SR, O'Hare MJ. The mammary myoepithelial cell--Cinderella or ugly sister? Breast Cancer Res 2001; 3:1-4. [PMID: 11250738 PMCID: PMC138667 DOI: 10.1186/bcr260] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2000] [Accepted: 09/26/2000] [Indexed: 11/10/2022] Open
Abstract
The breast myoepithelial cell is the Cinderella of mammary biology. Although its contribution to benign and some malignant pathologies is recognised, it has been largely neglected in molecular and biological studies. The reason for this has been the perception that its role in normal physiology is confined to lactation and the belief that most breast cancers arise from luminal epithelial cells. This review presents our perspective on its broader biological significance and its potential use as a model system for understanding breast carcinogenesis.
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Affiliation(s)
- S R Lakhani
- Breast Molecular Pathology Laboratory, Department of Histopathology, Royal Free and University College Medical School, London, UK.
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48
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Cui W, Allen ND, Skynner M, Gusterson B, Clark AJ. Inducible ablation of astrocytes shows that these cells are required for neuronal survival in the adult brain. Glia 2001; 34:272-82. [PMID: 11360300 DOI: 10.1002/glia.1061] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
To study the function of astrocytes in the adult brain, we have targeted the expression of E. coli nitroreductase (NTR) to the astrocytes of transgenic mice under the control of the GFAP promoter. The astrocytes expressing NTR were selectively ablated after administration of the prodrug CB1954, resulting in motor discoordination. Histological examination showed that the region most affected in the brain was the cerebellum, in which the Bergmann glia were eliminated and the granular neurons had degenerated. Specific effects were also noted on the dendrites of the Purkinje cells, and the junction between these neurons and granular layer was disrupted. Astrocyte ablation was associated with a dramatic decrease in the expression of glutamate transporters, which may account for the degeneration of granular neurons since the excitotoxic effects of glutamate result in a similar phenotype. These results provide the first evidence that astrocytes are important for the survival of neurons in the adult brain in vivo.
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Affiliation(s)
- W Cui
- Division of Gene Expression and Development, Roslin Institute, Roslin, Midlothian, UK
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49
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Weedon SJ, Green NK, McNeish IA, Gilligan MG, Mautner V, Wrighton CJ, Mountain A, Young LS, Kerr DJ, Searle PF. Sensitisation of human carcinoma cells to the prodrug CB1954 by adenovirus vector-mediated expression of E. coli nitroreductase. Int J Cancer 2000; 86:848-54. [PMID: 10842200 DOI: 10.1002/(sici)1097-0215(20000615)86:6<848::aid-ijc14>3.0.co;2-b] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The enzyme nitroreductase from E. coli can reduce the weak, monofunctional alkylating agent 5-(aziridin-1-yl)-2, 4-dinitrobenzamide (CB1954) to a potent cytotoxic species that generates interstrand crosslinks in DNA. Nitroreductase therefore has potential as a "suicide enzyme" for cancer gene therapy, as cells that express nitroreductase become selectively sensitive to the prodrug CB1954. We have incorporated a nitroreductase expression cassette into a replication-defective adenovirus vector (Ad-CMV-ntr), which allowed efficient gene transfer to SK-OV-3 or IGROV-1 ovarian carcinoma cells. Nitroreductase levels increased in line with multiplicity of infection, and this was reflected in increasing sensitisation of the cells to CB1954, reaching an optimum (approx. 2, 000-fold sensitisation) with 25-50 p.f.u. per cell. Similar Ad-CMV-ntr-dependent sensitisation to CB1954 was seen in 3 of 6 low-passage primary ovarian tumour lines. Cells grown at low-serum concentration to inhibit proliferation remained equally susceptible to the Ad-CMV-ntr-dependent cytotoxicity of CB1954, indicating a distinct advantage over retroviral gene delivery and other popular enzyme-prodrug systems for human tumours with a low rate of cell proliferation. Additionally, cisplatin-resistant cells were sensitised towards CB1954 by Ad-CMV-ntr as efficiently as the parental cells, indicating that the system could be effective in patients with cisplatin-resistant tumours. In a murine xenograft model for disseminated peritoneal carcinomatosis with ascites, treatment of nude mice bearing intraperitoneal SUIT2 tumours with Ad-CMV-ntr and CB1954 almost doubled the median survival from 14 to 26 days (p < 0.0001).
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Affiliation(s)
- S J Weedon
- The University of Birmingham CRC Institute for Cancer Studies, Edgbaston, Birmingham, United Kingdom
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Abstract
The establishment of novel animal models using gene targeting and transgenic technology has opened a new area of neuropharmacological research. For the first time, it became possible to alter the expression of a gene in a specific cell type of an intact animal by either overexpression, inhibition or ablation. This review describes the technology and lists the relevant tools, such as reporter genes, suicide genes, immortalizing genes, and promoters, necessary for the targeted expression of these and other genes in specific cells of the central nervous system. In addition, the problem is discussed that the mouse is the species in which this technology is by far the most developed, while the rat has been used as the model species for neuropharmacology during the last century.
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Affiliation(s)
- M Bader
- Max-Delbrück-Center for Molecular Medicine, Transgenics in Berlin-Buch GmbH, Berlin, Germany
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