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Riethdorf S, O'Flaherty L, Hille C, Pantel K. Clinical applications of the CellSearch platform in cancer patients. Adv Drug Deliv Rev 2018; 125:102-121. [PMID: 29355669 DOI: 10.1016/j.addr.2018.01.011] [Citation(s) in RCA: 154] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 01/12/2018] [Accepted: 01/15/2018] [Indexed: 12/29/2022]
Abstract
The CellSearch® system (CS) enables standardized enrichment and enumeration of circulating tumor cells (CTCs) that are repeatedly assessable via non-invasive "liquid biopsy". While the association of CTCs with poor clinical outcome for cancer patients has clearly been demonstrated in numerous clinical studies, utilizing CTCs for the identification of therapeutic targets, stratification of patients for targeted therapies and uncovering mechanisms of resistance is still under investigation. Here, we comprehensively review the current benefits and drawbacks of clinical CTC analyses for patients with metastatic and non-metastatic tumors. Furthermore, the review focuses on approaches beyond CTC enumeration that aim to uncover therapeutically relevant antigens, genomic aberrations, transcriptional profiles and epigenetic alterations of CTCs at a single cell level. This characterization of CTCs may shed light on the heterogeneity and genomic landscapes of malignant tumors, an understanding of which is highly important for the development of new therapeutic strategies.
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2
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Abstract
By identifying and tracking genetic changes in primary tumors and metastases, patients can be stratified for the most efficient therapeutic regimen by screening for known biomarkers. However, retrieving tissues biopsies is not always feasible due to tumor location or risk to patient. Therefore, a liquid biopsies approach offers an appealing solution to an otherwise invasive procedure. The rapid growth of the liquid biopsy field has been aided by improvements in the sensitivity and specificity of enrichment assays for isolating circulating tumor cells (CTCs) from normal surrounding blood cells. Furthermore, the identification and molecular characterization of CTCs has been shown in numerous studies to be of diagnostic and prognostic relevance in breast, prostate and colon cancer patients. Despite these advancements, and the highly metastatic nature of lung cancer, it remains a challenge to detect CTCs in advanced non-small cell lung cancer (NSCLC). It may be that loss of epithelial features, in favor of a mesenchymal phenotype, and the highly heterogeneous nature of NSCLC CTCs contribute to their evasion from current detection methods. By identifying a broader spectrum of biomarkers that could better differentiate the various NSCLC CTCs subpopulations, it may be possible to not only improve detection rates but also to shed light on which CTC clones are likely to drive metastatic initiation. Here we review the biology of CTCs and describe a number of proteins and genetic targets which could potentially be utilized for the dissemination of heterogenic subpopulations of CTCs in NSCLC.
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Affiliation(s)
- Linda O'Flaherty
- Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach, Germany.,Institute of Tumor Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Harriet Wikman
- Institute of Tumor Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Klaus Pantel
- Institute of Tumor Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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O'Flaherty L, Mawhinney A, Hickland P. Reversing anticoagulation in head injury: Better sooner than later, but are we compliant? Int J Surg 2015. [DOI: 10.1016/j.ijsu.2015.07.525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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4
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Adam J, Yang M, Bauerschmidt C, Kitagawa M, O'Flaherty L, Maheswaran P, Özkan G, Sahgal N, Baban D, Kato K, Saito K, Iino K, Igarashi K, Stratford M, Pugh C, Tennant DA, Ludwig C, Davies B, Ratcliffe PJ, El-Bahrawy M, Ashrafian H, Soga T, Pollard PJ. A role for cytosolic fumarate hydratase in urea cycle metabolism and renal neoplasia. Cell Rep 2013; 3:1440-8. [PMID: 23643539 PMCID: PMC3675675 DOI: 10.1016/j.celrep.2013.04.006] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 03/24/2013] [Accepted: 04/08/2013] [Indexed: 11/28/2022] Open
Abstract
The identification of mutated metabolic enzymes in hereditary cancer syndromes has established a direct link between metabolic dysregulation and cancer. Mutations in the Krebs cycle enzyme, fumarate hydratase (FH), predispose affected individuals to leiomyomas, renal cysts, and cancers, though the respective pathogenic roles of mitochondrial and cytosolic FH isoforms remain undefined. On the basis of comprehensive metabolomic analyses, we demonstrate that FH1-deficient cells and tissues exhibit defects in the urea cycle/arginine metabolism. Remarkably, transgenic re-expression of cytosolic FH ameliorated both renal cyst development and urea cycle defects associated with renal-specific FH1 deletion in mice. Furthermore, acute arginine depletion significantly reduced the viability of FH1-deficient cells in comparison to controls. Our findings highlight the importance of extramitochondrial metabolic pathways in FH-associated oncogenesis and the urea cycle/arginine metabolism as a potential therapeutic target.
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Affiliation(s)
- Julie Adam
- Cancer Biology and Metabolism Group, Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN, UK
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5
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Adam J, Hatipoglu E, O'Flaherty L, Ternette N, Sahgal N, Lockstone H, Baban D, Nye E, Stamp G, Wolhuter K, Stevens M, Fischer R, Carmeliet P, Maxwell P, Pugh C, Frizzell N, Soga T, Kessler B, El-Bahrawy M, Ratcliffe P, Pollard P. Renal cyst formation in Fh1-deficient mice is independent of the Hif/Phd pathway: roles for fumarate in KEAP1 succination and Nrf2 signaling. Cancer Cell 2011; 20:524-37. [PMID: 22014577 PMCID: PMC3202623 DOI: 10.1016/j.ccr.2011.09.006] [Citation(s) in RCA: 444] [Impact Index Per Article: 34.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2011] [Revised: 08/23/2011] [Accepted: 09/20/2011] [Indexed: 12/11/2022]
Abstract
The Krebs cycle enzyme fumarate hydratase (FH) is a human tumor suppressor whose inactivation is associated with the development of leiomyomata, renal cysts, and tumors. It has been proposed that activation of hypoxia inducible factor (HIF) by fumarate-mediated inhibition of HIF prolyl hydroxylases drives oncogenesis. Using a mouse model, we provide genetic evidence that Fh1-associated cyst formation is Hif independent, as is striking upregulation of antioxidant signaling pathways revealed by gene expression profiling. Mechanistic analysis revealed that fumarate modifies cysteine residues within the Kelch-like ECH-associated protein 1 (KEAP1), abrogating its ability to repress the Nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-mediated antioxidant response pathway, suggesting a role for Nrf2 dysregulation in FH-associated cysts and tumors.
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Affiliation(s)
- Julie Adam
- Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN, UK
| | - Emine Hatipoglu
- Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN, UK
| | - Linda O'Flaherty
- Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN, UK
| | - Nicola Ternette
- Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN, UK
| | - Natasha Sahgal
- Bioinformatics and Statistical Genetics, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Helen Lockstone
- Bioinformatics and Statistical Genetics, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Dilair Baban
- High Throughput Genomics, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Emma Nye
- Experimental Histopathology Laboratory, Cancer Research UK London Research Institute, London WC2A 3LY, UK
| | - Gordon W. Stamp
- Experimental Histopathology Laboratory, Cancer Research UK London Research Institute, London WC2A 3LY, UK
- Department of Histopathology, Royal Marsden Hospital, London WC2A 3LY, UK
| | - Kathryn Wolhuter
- Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN, UK
| | - Marcus Stevens
- Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN, UK
| | - Roman Fischer
- Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN, UK
| | - Peter Carmeliet
- Laboratory of Angiogenesis and Neurovascular Link, Vesalius Research Center, VIB Leuven B-3000, Belgium
- Laboratory of Angiogenesis and Neurovascular Link, Vesalius Research Center, K.U. Leuven, Leuven B-3000, Belgium
| | | | - Chris W. Pugh
- Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN, UK
| | - Norma Frizzell
- Department of Exercise Science, School of Public Health, University of South Carolina, Columbia, SC 29208, USA
| | - Tomoyoshi Soga
- Institute for Advanced Biosciences, Keio University, 403-1 Daihoji, Tsuruoka, Yamagata 997-0017, Japan
| | - Benedikt M. Kessler
- Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN, UK
| | - Mona El-Bahrawy
- Department of Histopathology, Imperial College, Hammersmith Hospital, London W12 0NN, UK
| | - Peter J. Ratcliffe
- Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN, UK
- Corresponding author
| | - Patrick J. Pollard
- Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN, UK
- Corresponding author
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Zhdanov AV, Favre C, O'Flaherty L, Adam J, O'Connor R, Pollard PJ, Papkovsky DB. Comparative bioenergetic assessment of transformed cells using a cell energy budget platform. Integr Biol (Camb) 2011; 3:1135-42. [PMID: 22005712 DOI: 10.1039/c1ib00050k] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The aberrant expression and functional activity of proteins involved in ATP production pathways may cause a crisis in energy generation for cells and compromise their survival under stressful conditions such as excitation, starvation, pharmacological treatment or disease states. Under resting conditions such defects are often compensated for, and therefore masked by, alternative pathways which have significant spare capacity. Here we present a multiplexed 'cell energy budget' platform which facilitates metabolic assessment and cross-comparison of different cells and the identification of genes directly or indirectly involved in ATP production. Long-decay emitting O(2) and pH sensitive probes and time-resolved fluorometry are used to measure changes in cellular O(2) consumption, glycolytic and total extracellular acidification (ECA), along with the measurement of total ATP and protein content in multiple samples. To assess the extent of spare capacity in the main energy pathways, the cells are also analysed following double-treatment with carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone and oligomycin. The four-parametric platform operating in a high throughput format has been validated with two panels of transformed cells: mouse embryonic fibroblasts (MEFs) lacking the Krebs cycle enzyme fumarate hydratase (Fh1) and HeLa cells with reduced expression of pyrimidine nucleotide carrier 1. In both cases, a marked reduction in both respiration and spare respiratory capacity was observed, accompanied by a compensatory activation of glycolysis and consequent maintenance of total ATP levels. At the same time, in Fh1-deficient MEFs the contribution of non-glycolytic pathways to the ECA did not change.
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Affiliation(s)
- A V Zhdanov
- Biochemistry Department, University College Cork, Cavanagh Pharmacy Building, College Road, Cork, Ireland
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7
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Bardella C, El-Bahrawy M, Frizzell N, Adam J, Ternette N, Hatipoglu E, Howarth K, O'Flaherty L, Roberts I, Turner G, Taylor J, Giaslakiotis K, Macaulay VM, Harris AL, Chandra A, Lehtonen HJ, Launonen V, Aaltonen LA, Pugh CW, Mihai R, Trudgian D, Kessler B, Baynes JW, Ratcliffe PJ, Tomlinson IP, Pollard PJ. Aberrant succination of proteins in fumarate hydratase-deficient mice and HLRCC patients is a robust biomarker of mutation status. J Pathol 2011; 225:4-11. [DOI: 10.1002/path.2932] [Citation(s) in RCA: 198] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Revised: 04/28/2011] [Accepted: 05/03/2011] [Indexed: 01/22/2023]
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8
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Thalhammer A, Bencokova Z, Poole R, Loenarz C, Adam J, O'Flaherty L, Schödel J, Mole D, Giaslakiotis K, Schofield CJ, Hammond EM, Ratcliffe PJ, Pollard PJ. Human AlkB homologue 5 is a nuclear 2-oxoglutarate dependent oxygenase and a direct target of hypoxia-inducible factor 1α (HIF-1α). PLoS One 2011; 6:e16210. [PMID: 21264265 PMCID: PMC3021549 DOI: 10.1371/journal.pone.0016210] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Accepted: 12/13/2010] [Indexed: 01/10/2023] Open
Abstract
Human 2-oxoglutarate oxygenases catalyse a range of biological oxidations including the demethylation of histone and nucleic acid substrates and the hydroxylation of proteins and small molecules. Some of these processes are centrally involved in regulation of cellular responses to hypoxia. The ALKBH proteins are a sub-family of 2OG oxygenases that are defined by homology to the Escherichia coli DNA-methylation repair enzyme AlkB. Here we report evidence that ALKBH5 is probably unique amongst the ALKBH genes in being a direct transcriptional target of hypoxia inducible factor-1 (HIF-1) and is induced by hypoxia in a range of cell types. We show that purified recombinant ALKBH5 is a bona fide 2OG oxygenase that catalyses the decarboxylation of 2OG but appears to have different prime substrate requirements from those so far defined for other ALKBH family members. Our findings define a new class of HIF-transcriptional target gene and suggest that ALKBH5 may have a role in the regulation of cellular responses to hypoxia.
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Affiliation(s)
- Armin Thalhammer
- Chemistry Research Laboratory and The Oxford Centre for Integrative Systems Biology, Department of Chemistry, University of Oxford, Oxford, United Kingdom
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9
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Ashrafian H, O'Flaherty L, Adam J, Steeples V, Chung YL, East P, Vanharanta S, Lehtonen H, Nye E, Hatipoglu E, Miranda M, Howarth K, Shukla D, Troy H, Griffiths J, Spencer-Dene B, Yusuf M, Volpi E, Maxwell PH, Stamp G, Poulsom R, Pugh CW, Costa B, Bardella C, Di Renzo MF, Kotlikoff MI, Launonen V, Aaltonen L, El-Bahrawy M, Tomlinson I, Pollard PJ. Expression profiling in progressive stages of fumarate-hydratase deficiency: the contribution of metabolic changes to tumorigenesis. Cancer Res 2010; 70:9153-65. [PMID: 20978192 DOI: 10.1158/0008-5472.can-10-1949] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is caused by mutations in the Krebs cycle enzyme fumarate hydratase (FH). It has been proposed that "pseudohypoxic" stabilization of hypoxia-inducible factor-α (HIF-α) by fumarate accumulation contributes to tumorigenesis in HLRCC. We hypothesized that an additional direct consequence of FH deficiency is the establishment of a biosynthetic milieu. To investigate this hypothesis, we isolated primary mouse embryonic fibroblast (MEF) lines from Fh1-deficient mice. As predicted, these MEFs upregulated Hif-1α and HIF target genes directly as a result of FH deficiency. In addition, detailed metabolic assessment of these MEFs confirmed their dependence on glycolysis, and an elevated rate of lactate efflux, associated with the upregulation of glycolytic enzymes known to be associated with tumorigenesis. Correspondingly, Fh1-deficient benign murine renal cysts and an advanced human HLRCC-related renal cell carcinoma manifested a prominent and progressive increase in the expression of HIF-α target genes and in genes known to be relevant to tumorigenesis and metastasis. In accord with our hypothesis, in a variety of different FH-deficient tissues, including a novel murine model of Fh1-deficient smooth muscle, we show a striking and progressive upregulation of a tumorigenic metabolic profile, as manifested by increased PKM2 and LDHA protein. Based on the models assessed herein, we infer that that FH deficiency compels cells to adopt an early, reversible, and progressive protumorigenic metabolic milieu that is reminiscent of that driving the Warburg effect. Targets identified in these novel and diverse FH-deficient models represent excellent potential candidates for further mechanistic investigation and therapeutic metabolic manipulation in tumors.
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MESH Headings
- Animals
- Carcinoma, Renal Cell/genetics
- Carcinoma, Renal Cell/metabolism
- Carcinoma, Renal Cell/pathology
- Cell Proliferation
- Cells, Cultured
- Embryo, Mammalian/cytology
- Female
- Fibroblasts/cytology
- Fibroblasts/metabolism
- Fumarate Hydratase/deficiency
- Fumarate Hydratase/genetics
- Gene Expression Profiling
- Gene Expression Regulation, Enzymologic
- Glycolysis
- Humans
- Hypoxia-Inducible Factor 1, alpha Subunit/genetics
- Hypoxia-Inducible Factor 1, alpha Subunit/metabolism
- Kidney Neoplasms/genetics
- Kidney Neoplasms/metabolism
- Kidney Neoplasms/pathology
- Leiomyomatosis/genetics
- Leiomyomatosis/metabolism
- Leiomyomatosis/pathology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle, Smooth/metabolism
- Muscle, Smooth/pathology
- Neoplasms/genetics
- Neoplasms/metabolism
- Neoplasms/pathology
- Oligonucleotide Array Sequence Analysis
- Reverse Transcriptase Polymerase Chain Reaction
- Spectral Karyotyping
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Affiliation(s)
- Houman Ashrafian
- Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Headington, United Kingdom
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10
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O'Flaherty L, Adam J, Heather LC, Zhdanov AV, Chung YL, Miranda MX, Croft J, Olpin S, Clarke K, Pugh CW, Griffiths J, Papkovsky D, Ashrafian H, Ratcliffe PJ, Pollard PJ. Dysregulation of hypoxia pathways in fumarate hydratase-deficient cells is independent of defective mitochondrial metabolism. Hum Mol Genet 2010; 19:3844-51. [PMID: 20660115 PMCID: PMC2935862 DOI: 10.1093/hmg/ddq305] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Accepted: 07/13/2010] [Indexed: 12/26/2022] Open
Abstract
Mutations in the gene encoding the Krebs cycle enzyme fumarate hydratase (FH) predispose to hereditary leiomyomatosis and renal cell cancer in affected individuals. FH-associated neoplasia is characterized by defective mitochondrial function and by upregulation of transcriptional pathways mediated by hypoxia-inducible factor (HIF), although whether and by what means these processes are linked has been disputed. We analysed the HIF pathway in Fh1-/- mouse embryonic fibroblasts (MEFs), in FH-defective neoplastic tissues and in Fh1-/- MEFs re-expressing either wild-type or an extra-mitochondrial restricted form of FH. These experiments demonstrated that upregulation of HIF-1alpha occurs as a direct consequence of FH inactivation. Fh1-/- cells accumulated intracellular fumarate and manifested severe impairment of HIF prolyl but not asparaginyl hydroxylation which was corrected by provision of exogenous 2-oxoglutarate (2-OG). Re-expression of the extra-mitochondrial form of FH in Fh1-/- cells was sufficient to reduce intracellular fumarate and to correct dysregulation of the HIF pathway completely, even in cells that remained profoundly defective in mitochondrial energy metabolism. The findings indicate that upregulation of HIF-1alpha arises from competitive inhibition of the 2-OG-dependent HIF hydroxylases by fumarate and not from disruption of mitochondrial energy metabolism.
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Affiliation(s)
- Linda O'Flaherty
- Henry Wellcome Building for Molecular Physiology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Julie Adam
- Henry Wellcome Building for Molecular Physiology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Lisa C. Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford OX1 3QX, UK
| | - Alexander V. Zhdanov
- Department of Biochemistry, University College Cork, Cavanagh Pharmacy Building, 1.28 College Road, Cork, Ireland
| | - Yuen-Li Chung
- CRUK and ESPRC Cancer Imaging Centre, Institute of Cancer Research and Royal Marsden Hospital, Sutton, Surrey SM2 5PT, UK
| | - Melroy X. Miranda
- Henry Wellcome Building for Molecular Physiology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Joanne Croft
- The Sheffield Children's NHS Trust, Immuno Bank, Sheffield S10 2TH, UK
| | - Simon Olpin
- The Sheffield Children's NHS Trust, Immuno Bank, Sheffield S10 2TH, UK
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford OX1 3QX, UK
| | - Christopher W. Pugh
- Henry Wellcome Building for Molecular Physiology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - John Griffiths
- Cancer Research UK Cambridge Research Institute, Li Ka Shing Centre, Robinson Way, Cambridge CB2 0RE, UK and
| | - Dmitri Papkovsky
- Department of Biochemistry, University College Cork, Cavanagh Pharmacy Building, 1.28 College Road, Cork, Ireland
| | - Houman Ashrafian
- Department of Cardiovascular Medicine, University of Oxford, Level 6, West Wing, John Radcliffe Hospital, Headley Way, Headington, Oxford OX3 9DU, UK
| | - Peter J. Ratcliffe
- Henry Wellcome Building for Molecular Physiology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Patrick J. Pollard
- Henry Wellcome Building for Molecular Physiology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
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Affiliation(s)
- L O'Flaherty
- Columbia University School of Nursing, New York, New York, USA
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12
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Abstract
Immunonutrition generally refers to the effect of the provision of specific nutrients on the immune system. These nutrients typically have immunoenhancing properties, and recent advances in nutrition support involve studies designed to exploit the desirable biological properties of these nutrients. The term immunonutrition strictly implies that we are focusing on the effect of certain nutrients on aspects of the immune system. However, in reality immunonutrition also refers to studies that not only examine the function of lymphocytes and leucocytes, but which also study the influence of key nutrients on the acute-phase response, the inflammatory response and on gastrointestinal structure and function. The interest, therefore, is on the impact of immunonutrition on all aspects of host defence mechanisms in response to a catabolic stress. Major surgery evokes an acute-phase response, a transient immunosuppression and alterations in gastrointestinal function. Normal function is usually restored after a few days; however, in a subgroup of patients homeostasis may be lost and development of the systemic inflammatory response syndrome (SIRS) ensues. Results of recent clinical trials suggest that provision of immunomodulatory nutrients, including glutamine, arginine, n-3 polyunsaturated fatty acids and dietary nucleotides, may promote restoration of normal tissue function post-operatively and prevent the occurrence of SIRS.
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Affiliation(s)
- L O'Flaherty
- Department of Surgery, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin, Republic of Ireland.
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Abstract
Taurine (2-aminoethane sulphonic acid), a ubiquitous beta-amino acid is conditionally essential in man. It is not utilized in protein synthesis but found free or in some simple peptides. Derived from methionine and cysteine metabolism, taurine is known to play a pivotal role in numerous physiological functions. Some of the roles with which taurine has been associated include osmoregulation, antioxidation, detoxification and stimulation of glycolysis and glycogenesis. Intracellular taurine is maintained at high concentrations in a variety of cell types and alteration of cell taurine levels is difficult. The role of taurine within the cell appears to be determined by the cell type. Recent research has determined a regulatory role for taurinechloramine, the product formed by the reaction between taurine and neutrophil derived hypochlorous acid on macrophage function. Plasma taurine levels are also high, although decreases are observed in response to surgical injury and numerous pathological conditions including cancer and sepsis. Supplementary taurine replenishes decreased plasma taurine. Although commonly used as a dietary supplement in the Far East, the potential advantages of dietary taurine supplementation have not as yet been fully recognized in the Western World; this is an area which could prove to be beneficial in the clinical arena.
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Affiliation(s)
- P P Stapleton
- Royal College of Surgeons in Ireland, Department of Surgery, Beaumont Hospital, Dublin, Ireland
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14
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Abstract
Intestinal uptake of dietary taurine is an important contributor to taurine homeostasis and may become crucial when taurine metabolism is impaired. This review aims to assess the literature documenting taurine transport and review what is currently known about the operation of the enterocyte taurine transport protein. Sources included MedLine searches from the last 10 years and references from original and review articles. The aim was to include human and animal studies directly addressing the subject of taurine uptake by enterocytes. Intestinal taurine transport has been well documented in in vivo studies using many different animal models. The mechanistic/kinetic aspects of the transport system have been extensively documented. However, little is known about what regulates the system. The recent development of a cell culture model of intestinal taurine transport will allow studies to explore the regulation of gut taurine uptake, which promises to be a very exciting area.
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Affiliation(s)
- L O'Flaherty
- Royal College of Surgeons in Ireland, Department of Surgery, Beaumont Hospital, Dublin, Ireland
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15
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Abstract
Intracellular enterocytic levels of the immunomodulator taurine decrease significantly in response to trauma and surgical insult. The effect of physiological stress on enterocyte taurine uptake is unknown. The aim of this study was to compare taurine transport under basal and stressed conditions using the human intestinal Caco-2 cell line in vitro. Caco-2 cells were incubated with 10 nM [1,2-3H]taurine at 37 degrees C and 5% CO2 and taurine uptake was examined over the range of 0.1-10 microM to determine kinetic parameters of the transporter. The culture medium was then supplemented with dexamethasone and/or lipopolysaccharide (LPS) and taurine uptake was calculated as picomoles per milligram protein per hour. Statistics were by unpaired Student's t test. Taurine uptake was hyperbolically related to taurine concentration and obeyed Michaelis-Menten kinetics with a K(m) of 5.27 +/- 0.95 microM and Vmax of 1125.43 +/- 130.9 pmole/mg protein/ hour. Dexamethasone (1-1000 microM) significantly reduced taurine uptake by up to 66.15%. LPS (1 microgram/ml) impaired transport of taurine by 15.7%, and in combination with dexamethasone (100 microM) by 42.4%. All results are mean of at least three experiments and P < 0.05. We have established that taurine uptake by enterocytes is downregulated by dexamethasone. This may relate to the decreased intestinal levels of taurine observed in trauma and surgery patients. Further study may elucidate mechanisms whereby homeostasis of enterocyte taurine might be maintained during sepsis.
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Affiliation(s)
- L O'Flaherty
- Royal College of Surgeons in Ireland, Department of Surgery, Beaumont Hospital, Dublin, Ireland
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