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Cooper AJL, Dorai T, Pinto JT, Denton TT. Metabolic Heterogeneity, Plasticity, and Adaptation to "Glutamine Addiction" in Cancer Cells: The Role of Glutaminase and the GTωA [Glutamine Transaminase-ω-Amidase (Glutaminase II)] Pathway. BIOLOGY 2023; 12:1131. [PMID: 37627015 PMCID: PMC10452834 DOI: 10.3390/biology12081131] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 07/06/2023] [Accepted: 07/21/2023] [Indexed: 08/27/2023]
Abstract
Many cancers utilize l-glutamine as a major energy source. Often cited in the literature as "l-glutamine addiction", this well-characterized pathway involves hydrolysis of l-glutamine by a glutaminase to l-glutamate, followed by oxidative deamination, or transamination, to α-ketoglutarate, which enters the tricarboxylic acid cycle. However, mammalian tissues/cancers possess a rarely mentioned, alternative pathway (the glutaminase II pathway): l-glutamine is transaminated to α-ketoglutaramate (KGM), followed by ω-amidase (ωA)-catalyzed hydrolysis of KGM to α-ketoglutarate. The name glutaminase II may be confused with the glutaminase 2 (GLS2) isozyme. Thus, we recently renamed the glutaminase II pathway the "glutamine transaminase-ω-amidase (GTωA)" pathway. Herein, we summarize the metabolic importance of the GTωA pathway, including its role in closing the methionine salvage pathway, and as a source of anaplerotic α-ketoglutarate. An advantage of the GTωA pathway is that there is no net change in redox status, permitting α-ketoglutarate production during hypoxia, diminishing cellular energy demands. We suggest that the ability to coordinate control of both pathways bestows a metabolic advantage to cancer cells. Finally, we discuss possible benefits of GTωA pathway inhibitors, not only as aids to studying the normal biological roles of the pathway but also as possible useful anticancer agents.
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Affiliation(s)
- Arthur J. L. Cooper
- Department of Biochemistry and Molecular Biology, New York Medical College, 15 Dana Road, Valhalla, NY 10595, USA; (T.D.); (J.T.P.)
| | - Thambi Dorai
- Department of Biochemistry and Molecular Biology, New York Medical College, 15 Dana Road, Valhalla, NY 10595, USA; (T.D.); (J.T.P.)
- Department of Urology, New York Medical College, Valhalla, NY 10595, USA
| | - John T. Pinto
- Department of Biochemistry and Molecular Biology, New York Medical College, 15 Dana Road, Valhalla, NY 10595, USA; (T.D.); (J.T.P.)
| | - Travis T. Denton
- Department Pharmaceutical Sciences, College of Pharmacy & Pharmaceutical Sciences, Washington State University Health Sciences Spokane, Spokane, WA 99202, USA
- Department of Translational Medicine and Physiology, Elson S. Floyd College of Medicine, Washington State University Health Sciences Spokane, Spokane, WA 99164, USA
- Steve Gleason Institute for Neuroscience, Washington State University Health Sciences Spokane, Spokane, WA 99164, USA
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2
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Lorenzo-López L, Lema-Arranz C, Fernández-Bertólez N, Costa S, Costa C, Teixeira JP, Pásaro E, Valdiglesias V, Laffon B. Relationship between DNA damage measured by the comet-assay and cognitive function. MUTATION RESEARCH/GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2022; 883-884:503557. [DOI: 10.1016/j.mrgentox.2022.503557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 09/25/2022] [Accepted: 10/05/2022] [Indexed: 11/06/2022]
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3
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The metabolic importance of the glutaminase II pathway in normal and cancerous cells. Anal Biochem 2020; 644:114083. [PMID: 33352190 DOI: 10.1016/j.ab.2020.114083] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 12/08/2020] [Accepted: 12/15/2020] [Indexed: 02/08/2023]
Abstract
In rapidly dividing cells, including many cancer cells, l-glutamine is a major energy source. Utilization of glutamine is usually depicted as: l-glutamine → l-glutamate (catalyzed by glutaminase isozymes; GLS1 and GLS2), followed by l-glutamate → α-ketoglutarate [catalyzed by glutamate-linked aminotransferases or by glutamate dehydrogenase (GDH)]. α-Ketoglutarate is a major anaplerotic component of the tricarboxylic acid (TCA) cycle. However, the glutaminase II pathway also converts l-glutamine to α-ketoglutarate. This pathway consists of a glutamine transaminase coupled to ω-amidase [Net reaction: l-Glutamine + α-keto acid + H2O → α-ketoglutarate + l-amino acid + NH4+]. This review focuses on the biological importance of the glutaminase II pathway, especially in relation to metabolism of cancer cells. Our studies suggest a component enzyme of the glutaminase II pathway, ω-amidase, is utilized by tumor cells to provide anaplerotic carbon. Inhibitors of GLS1 are currently in clinical trials as anti-cancer agents. However, this treatment will not prevent the glutaminase II pathway from providing anaplerotic carbon derived from glutamine. Specific inhibitors of ω-amidase, perhaps in combination with a GLS1 inhibitor, may provide greater therapeutic efficacy.
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Muruzabal D, Collins A, Azqueta A. The enzyme-modified comet assay: Past, present and future. Food Chem Toxicol 2020; 147:111865. [PMID: 33217526 DOI: 10.1016/j.fct.2020.111865] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 11/08/2020] [Accepted: 11/13/2020] [Indexed: 12/17/2022]
Abstract
The enzyme-modified comet assay was developed in order to detect DNA lesions other than those detected by the standard version (single and double strand breaks and alkali-labile sites). Various lesion-specific enzymes, from the DNA repair machinery of bacteria and humans, have been combined with the comet assay, allowing detection of different oxidized and alkylated bases as well as cyclobutane pyrimidine dimers, mis-incorporated uracil and apurinic/apyrimidinic sites. The enzyme-modified comet assay has been applied in different fields - human biomonitoring, environmental toxicology, and genotoxicity testing (both in vitro and in vivo) - as well as in basic research. Up to now, twelve enzymes have been employed; here we describe the enzymes and give examples of studies in which they have been applied. The bacterial formamidopyrimidine DNA glycosylase (Fpg) and endonuclease III (EndoIII) have been extensively used while others have been used only rarely. Adding further enzymes to the comet assay toolbox could potentially increase the variety of DNA lesions that can be detected. The enzyme-modified comet assay can play a crucial role in the elucidation of the mechanism of action of both direct and indirect genotoxins, thus increasing the value of the assay in the regulatory context.
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Affiliation(s)
- Damián Muruzabal
- Universidad de Navarra, Department of Pharmacology and Toxicology, Faculty of Pharmacy and Nutrition, Irunlarrea 1, 310008, Pamplona, Spain
| | - Andrew Collins
- Department of Nutrition, Institute for Basic Medical Sciences, University of Oslo, Sognsvannsveien 9, 0372, Oslo, Norway
| | - Amaya Azqueta
- Universidad de Navarra, Department of Pharmacology and Toxicology, Faculty of Pharmacy and Nutrition, Irunlarrea 1, 310008, Pamplona, Spain; IdiSNA, Navarra Institute for Health Research, Pamplona, Spain.
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5
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Folate Insufficiency Due to MTHFR Deficiency Is Bypassed by 5-Methyltetrahydrofolate. J Clin Med 2020; 9:jcm9092836. [PMID: 32887268 PMCID: PMC7564482 DOI: 10.3390/jcm9092836] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/21/2020] [Accepted: 08/31/2020] [Indexed: 12/14/2022] Open
Abstract
Adequate levels of folates are essential for homeostasis of the organism, prevention of congenital malformations, and the salvage of predisposed disease states. They depend on genetic predisposition, and therefore, a pharmacogenetic approach to individualized supplementation or therapeutic intervention is necessary for an optimal outcome. The role of folates in vital cell processes was investigated by translational pharmacogenetics employing lymphoblastoid cell lines (LCLs). Depriving cells of folates led to reversible S-phase arrest. Since 5,10-methylenetetrahydrofolate reductase (MTHFR) is the key enzyme in the biosynthesis of an active folate form, we evaluated the relevance of polymorphisms in the MTHFR gene on intracellular levels of bioactive metabolite, the 5-methyltetrahydrofolate (5-Me-THF). LCLs (n = 35) were divided into low- and normal-MTHFR activity groups based on their genotype. They were cultured in the presence of folic acid (FA) or 5-Me-THF. Based on the cells’ metabolic activity and intracellular 5-Me-THF levels, we conclude supplementation of FA is sufficient to maintain adequate folate level in the normal MTHFR activity group, while low MTHFR activity cells require 5-Me-THF to overcome the metabolic defects caused by polymorphisms in their MTHFR genes. This finding was supported by the determination of intracellular levels of 5-Me-THF in cell lysates by LC-MS/MS. FA supplementation resulted in a 2.5-fold increase in 5-Me-THF in cells with normal MTHFR activity, but there was no increase after FA supplementation in low MTHFR activity cells. However, when LCLs were exposed to 5-Me-THF, a 10-fold increase in intracellular levels of this metabolite was determined. These findings indicate that patients undergoing folate supplementation to counteract anti-folate therapies, or patients with increased folate demand, would benefit from pharmacogenetics-based therapy choices.
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Harbottle JA, Petrie L, Ruhe M, Houssen WE, Jaspars M, Kolb AF. A cell-based assay system for activators of the environmental cell stress response. Anal Biochem 2020; 592:113583. [PMID: 31945311 DOI: 10.1016/j.ab.2020.113583] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/31/2019] [Accepted: 01/11/2020] [Indexed: 12/23/2022]
Abstract
Improved health span and lifespan extension in a wide phylogenetic range of species is associated with the induction of the environmental cell stress response through a signalling pathway regulated by the transcription factor Nrf2. Phytochemicals which stimulate this response may form part of therapeutic interventions which stimulate endogenous cytoprotective mechanisms, thereby delaying the onset of age-related diseases and promoting healthy ageing in humans. In order to identify compounds that activate the Nrf2 pathway, a cell-based reporter system was established in HepG2 cells using a luciferase reporter gene under the control of the Nqo1 promoter. Sulforaphane, an isothiocyanate derived from cruciferous vegetables and a known activator of the Nrf2 pathway, was used to validate the reporter system. The transfected cell line HepG2 C1 was subsequently used to screen natural product libraries. Five compounds were identified as activating the bioluminescent reporter by greater than 5-fold. The two most potent compounds, MBC20 and MBC37, were further characterised and shown to stimulate endogenous cytoprotective gene and protein expression. The bioluminescent reporter system will allow rapid, in vitro identification of novel compounds that have the potential to improve health span through activation of the environmental stress response.
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Affiliation(s)
| | - Linda Petrie
- Metabolic Health Group, Obesity & Metabolic Health Theme, Rowett Institute, UK
| | - Madeleine Ruhe
- Metabolic Health Group, Obesity & Metabolic Health Theme, Rowett Institute, UK
| | - Wael E Houssen
- Marine Biodiscovery Centre, Chemistry Department, University of Aberdeen, Aberdeen, AB24 3UE, Scotland, UK; Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
| | - Marcel Jaspars
- Marine Biodiscovery Centre, Chemistry Department, University of Aberdeen, Aberdeen, AB24 3UE, Scotland, UK
| | - Andreas F Kolb
- Metabolic Health Group, Obesity & Metabolic Health Theme, Rowett Institute, UK.
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Catala GN, Bestwick CS, Russell WR, Tortora K, Giovannelli L, Moyer MP, Lendoiro E, Duthie SJ. Folate, genomic stability and colon cancer: The use of single cell gel electrophoresis in assessing the impact of folate in vitro, in vivo and in human biomonitoring. Mutat Res 2018; 843:73-80. [PMID: 31421742 DOI: 10.1016/j.mrgentox.2018.08.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 08/29/2018] [Accepted: 08/29/2018] [Indexed: 01/10/2023]
Abstract
Intake of folate (vitamin B9) is strongly inversely linked with human cancer risk, particularly colon cancer. In general, people with the highest dietary intake of folate or with high blood folate levels are at a reduced risk (approx. 25%) of developing colon cancer. Folate acts in normal cellular metabolism to maintain genomic stability through the provision of nucleotides for DNA replication and DNA repair and by regulating DNA methylation and gene expression. Folate deficiency can accelerate carcinogenesis by inducing misincorporation of uracil into DNA, by increasing DNA strand breakage, by inhibiting DNA base excision repair capacity and by inducing DNA hypomethylation and consequently aberrant gene and protein expression. Conversely, increasing folate intake may improve genomic stability. This review describes key applications of single cell gel electrophoresis (the comet assay) in assessing genomic instability (misincorporated uracil, DNA single strand breakage and DNA repair capacity) in response to folate status (deficient or supplemented) in human cells in vitro, in rodent models and in human case-control and intervention studies. It highlights an adaptation of the SCGE comet assay for measuring genome-wide and gene-specific DNA methylation in human cells and colon tissue.
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Affiliation(s)
- Gema Nadal Catala
- Natural Products Group, Division of Lifelong Health, Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | - Charles S Bestwick
- Natural Products Group, Division of Lifelong Health, Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | - Wendy R Russell
- Natural Products Group, Division of Lifelong Health, Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | - Katia Tortora
- Department NEUROFARBA, Section of Pharmacology and Toxicology, University of Florence, Florence, Italy
| | - Lisa Giovannelli
- Department NEUROFARBA, Section of Pharmacology and Toxicology, University of Florence, Florence, Italy
| | | | - Elena Lendoiro
- Department of Toxicology, Institute of Forensic Sciences, University of Santiago of Compostela, Santiago de Compostela, Spain; School of Pharmacy and Life Sciences, Robert Gordon University, Aberdeen, UK
| | - Susan J Duthie
- Natural Products Group, Division of Lifelong Health, Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK; School of Pharmacy and Life Sciences, Robert Gordon University, Aberdeen, UK.
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8
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Hearnden V, Powers HJ, Elmogassabi A, Lowe R, Murdoch C. Methyl-donor depletion of head and neck cancer cells in vitro establishes a less aggressive tumour cell phenotype. Eur J Nutr 2018; 57:1321-1332. [PMID: 28251343 PMCID: PMC5959985 DOI: 10.1007/s00394-017-1411-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 02/19/2017] [Indexed: 11/24/2022]
Abstract
PURPOSE DNA methylation plays a fundamental role in the epigenetic control of carcinogenesis and is, in part, influenced by the availability of methyl donors obtained from the diet. In this study, we developed an in-vitro model to investigate whether methyl donor depletion affects the phenotype and gene expression in head and neck squamous cell carcinoma (HNSCC) cells. METHODS HNSCC cell lines (UD-SCC2 and UPCI-SCC72) were cultured in medium deficient in methionine, folate, and choline or methyl donor complete medium. Cell doubling-time, proliferation, migration, and apoptosis were analysed. The effects of methyl donor depletion on enzymes controlling DNA methylation and the pro-apoptotic factors death-associated protein kinase-1 (DAPK1) and p53 upregulated modulator of apoptosis (PUMA) were examined by quantitative-PCR or immunoblotting. RESULTS HNSCC cells cultured in methyl donor deplete conditions showed significantly increased cell doubling times, reduced cell proliferation, impaired cell migration, and a dose-dependent increase in apoptosis when compared to cells cultured in complete medium. Methyl donor depletion significantly increased the gene expression of DNMT3a and TET-1, an effect that was reversed upon methyl donor repletion in UD-SCC2 cells. In addition, expression of DAPK1 and PUMA was increased in UD-SCC2 cells cultured in methyl donor deplete compared to complete medium, possibly explaining the observed increase in apoptosis in these cells. CONCLUSION Taken together, these data show that depleting HNSCC cells of methyl donors reduces the growth and mobility of HNSCC cells, while increasing rates of apoptosis, suggesting that a methyl donor depleted diet may significantly affect the growth of established HNSCC.
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Affiliation(s)
- Vanessa Hearnden
- Human Nutrition Unit, Department of Oncology, University of Sheffield, Sheffield, S10 2RX, UK
- School of Clinical Dentistry, University of Sheffield, Sheffield, S10 2TA, UK
| | - Hilary J Powers
- Human Nutrition Unit, Department of Oncology, University of Sheffield, Sheffield, S10 2RX, UK
| | - Abeir Elmogassabi
- Human Nutrition Unit, Department of Oncology, University of Sheffield, Sheffield, S10 2RX, UK
| | - Rosanna Lowe
- Human Nutrition Unit, Department of Oncology, University of Sheffield, Sheffield, S10 2RX, UK
| | - Craig Murdoch
- School of Clinical Dentistry, University of Sheffield, Sheffield, S10 2TA, UK.
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9
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Guo X, Ni J, Zhu Y, Zhou T, Ma X, Xue J, Wang X. Folate deficiency induces mitotic aberrations and chromosomal instability by compromising the spindle assembly checkpoint in cultured human colon cells. Mutagenesis 2017; 32:547-560. [DOI: 10.1093/mutage/gex030] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 10/30/2017] [Indexed: 01/10/2023] Open
Affiliation(s)
- Xihan Guo
- School of Life Sciences, The Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Yunnan Normal University, Kunming, Yunnan, China
- School of Life Sciences, Yunnan University, Kunming, Yunnan, China
| | - Juan Ni
- School of Life Sciences, The Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Yunnan Normal University, Kunming, Yunnan, China
| | - Yuqian Zhu
- School of Life Sciences, The Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Yunnan Normal University, Kunming, Yunnan, China
| | - Tao Zhou
- School of Life Sciences, The Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Yunnan Normal University, Kunming, Yunnan, China
| | - Xiaoling Ma
- China Gene Health Management Group, Ltd., Shanghai, China
| | - Jinglun Xue
- China Gene Health Management Group, Ltd., Shanghai, China
| | - Xu Wang
- School of Life Sciences, The Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Yunnan Normal University, Kunming, Yunnan, China
- School of Life Sciences, Yunnan University, Kunming, Yunnan, China
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10
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Folate deprivation induces cell cycle arrest at G0/G1 phase and apoptosis in hippocampal neuron cells through down-regulation of IGF-1 signaling pathway. Int J Biochem Cell Biol 2016; 79:222-230. [DOI: 10.1016/j.biocel.2016.08.040] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 07/26/2016] [Accepted: 08/29/2016] [Indexed: 02/06/2023]
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11
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Lamm N, Maoz K, Bester AC, Im MM, Shewach DS, Karni R, Kerem B. Folate levels modulate oncogene-induced replication stress and tumorigenicity. EMBO Mol Med 2016. [PMID: 26197802 PMCID: PMC4568948 DOI: 10.15252/emmm.201404824] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Chromosomal instability in early cancer stages is caused by replication stress. One mechanism by which oncogene expression induces replication stress is to drive cell proliferation with insufficient nucleotide levels. Cancer development is driven by alterations in both genetic and environmental factors. Here, we investigated whether replication stress can be modulated by both genetic and non-genetic factors and whether the extent of replication stress affects the probability of neoplastic transformation. To do so, we studied the effect of folate, a micronutrient that is essential for nucleotide biosynthesis, on oncogene-induced tumorigenicity. We show that folate deficiency by itself leads to replication stress in a concentration-dependent manner. Folate deficiency significantly enhances oncogene-induced replication stress, leading to increased DNA damage and tumorigenicity in vitro. Importantly, oncogene-expressing cells, when grown under folate deficiency, exhibit a significantly increased frequency of tumor development in mice. These findings suggest that replication stress is a quantitative trait affected by both genetic and non-genetic factors and that the extent of replication stress plays an important role in cancer development.
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Affiliation(s)
- Noa Lamm
- Department of Genetics, The Alexander Silberman Institute of Life Sciences Edmond J. Safra Campus The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Karin Maoz
- Department of Genetics, The Alexander Silberman Institute of Life Sciences Edmond J. Safra Campus The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Assaf C Bester
- Department of Genetics, The Alexander Silberman Institute of Life Sciences Edmond J. Safra Campus The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Michael M Im
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, MI, USA
| | - Donna S Shewach
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, MI, USA
| | - Rotem Karni
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Batsheva Kerem
- Department of Genetics, The Alexander Silberman Institute of Life Sciences Edmond J. Safra Campus The Hebrew University of Jerusalem, Jerusalem, Israel
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12
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ω-Amidase: an underappreciated, but important enzyme in l-glutamine and l-asparagine metabolism; relevance to sulfur and nitrogen metabolism, tumor biology and hyperammonemic diseases. Amino Acids 2015; 48:1-20. [DOI: 10.1007/s00726-015-2061-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 07/24/2015] [Indexed: 12/29/2022]
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13
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Farias N, Ho N, Butler S, Delaney L, Morrison J, Shahrzad S, Coomber BL. The effects of folic acid on global DNA methylation and colonosphere formation in colon cancer cell lines. J Nutr Biochem 2015; 26:818-26. [PMID: 25804133 DOI: 10.1016/j.jnutbio.2015.02.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 02/18/2015] [Accepted: 02/20/2015] [Indexed: 02/07/2023]
Abstract
Folate and its synthetic form, folic acid (FA), are essential vitamins for the regeneration of S-adenosyl methionine molecules, thereby maintaining adequate cellular methylation. The deregulation of DNA methylation is a contributing factor to carcinogenesis, as alterations in genetic methylation may contribute to stem cell reprogramming and dedifferentiation processes that lead to a cancer stem cell (CSC) phenotype. Here, we investigate the potential effects of FA exposure on DNA methylation and colonosphere formation in cultured human colorectal cancer (CRC) cell lines. We show for the first time that HCT116, LS174T, and SW480 cells grown without adequate FA demonstrate significantly impaired colonosphere forming ability with limited changes in CD133, CD166, and EpCAM surface expression. These differences were accompanied by concomitant changes to DNA methyltransferase (DNMT) enzyme expression and DNA methylation levels, which varied depending on cell line. Taken together, these results demonstrate an interaction between FA metabolism and CSC phenotype in vitro and help elucidate a connection between supplemental FA intake and CRC development.
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Affiliation(s)
- Nathan Farias
- Department of Biomedical Sciences, University of Guelph, Guelph, ON, Canada N1G 2W1.
| | - Nelson Ho
- Department of Biomedical Sciences, University of Guelph, Guelph, ON, Canada N1G 2W1.
| | - Stacey Butler
- Department of Biomedical Sciences, University of Guelph, Guelph, ON, Canada N1G 2W1.
| | - Leanne Delaney
- Department of Biomedical Sciences, University of Guelph, Guelph, ON, Canada N1G 2W1.
| | - Jodi Morrison
- Department of Biomedical Sciences, University of Guelph, Guelph, ON, Canada N1G 2W1.
| | | | - Brenda L Coomber
- Department of Biomedical Sciences, University of Guelph, Guelph, ON, Canada N1G 2W1.
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Duthie SJ, Beattie JH, Gordon MJ, Pirie LP, Nicol F, Reid MD, Duncan GJ, Cantlay L, Horgan G, McNeil CJ. Nutritional B vitamin deficiency alters the expression of key proteins associated with vascular smooth muscle cell proliferation and migration in the aorta of atherosclerotic apolipoprotein E null mice. GENES AND NUTRITION 2014; 10:446. [PMID: 25446494 DOI: 10.1007/s12263-014-0446-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 11/21/2014] [Indexed: 12/11/2022]
Abstract
Low B vitamin status is linked with human vascular disease. We employed a proteomic and biochemical approach to determine whether nutritional folate deficiency and/or hyperhomocysteinemia altered metabolic processes linked with atherosclerosis in ApoE null mice. Animals were fed either a control fat (C; 4 % w/w lard) or a high-fat [HF; 21 % w/w lard and cholesterol (0/15 % w/w)] diet with different B vitamin compositions for 16 weeks. Aorta tissue was prepared and global protein expression, B vitamin, homocysteine and lipoprotein status measured. Changes in the expression of aorta proteins were detected in response to multiple B vitamin deficiency combined with a high-fat diet (P < 0.05) and were strongly linked with lipoprotein concentrations measured directly in the aorta adventitia (P < 0.001). Pathway analysis revealed treatment effects in the aorta-related primarily to cytoskeletal organisation, smooth muscle cell adhesion and invasiveness (e.g., fibrinogen, moesin, transgelin, vimentin). Combined B vitamin deficiency induced striking quantitative changes in the expression of aorta proteins in atherosclerotic ApoE null mice. Deregulated expression of these proteins is associated with human atherosclerosis. Cellular pathways altered by B vitamin status included cytoskeletal organisation, cell differentiation and migration, oxidative stress and chronic inflammation. These findings provide new insight into the molecular mechanisms through which B vitamin deficiency may accelerate atherosclerosis.
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Affiliation(s)
- Susan J Duthie
- School of Pharmacy and Life Sciences, Robert Gordon University, Aberdeen, UK,
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15
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Hannibal L, DiBello PM, Jacobsen DW. Proteomics of vitamin B12 processing. Clin Chem Lab Med 2013; 51:477-88. [PMID: 23241609 DOI: 10.1515/cclm-2012-0568] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 10/23/2012] [Indexed: 12/18/2022]
Abstract
The causes of cobalamin (B12, Cbl) deficiency are multifactorial. Whether nutritional due to poor dietary intake, or functional due to impairments in absorption or intracellular processing and trafficking events, the major symptoms of Cbl deficiency include megaloblastic anemia, neurological deterioration and in extreme cases, failure to thrive and death. The common biomarkers of Cbl deficiency (hyperhomocysteinemia and methylmalonic acidemia) are extremely valuable diagnostic indicators of the condition, but little is known about the changes that occur at the protein level. A mechanistic explanation bridging the physiological changes associated with functional B12 deficiency with its intracellular processers and carriers is lacking. In this article, we will cover the effects of B12 deficiency in a cblC-disrupted background (also referred to as MMACHC) as a model of functional Cbl deficiency. As will be shown, major protein changes involve the cytoskeleton, the neurological system as well as signaling and detoxification pathways. Supplementation of cultured MMACHC-mutant cells with hydroxocobalamin (HOCbl) failed to restore these variants to the normal phenotype, suggesting that a defective Cbl processing pathway produces irreversible changes at the protein level.
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Affiliation(s)
- Luciana Hannibal
- Department of Pathobiology (NC2 – 104), Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
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Derry MM, Raina K, Agarwal C, Agarwal R. Identifying molecular targets of lifestyle modifications in colon cancer prevention. Front Oncol 2013; 3:119. [PMID: 23675573 PMCID: PMC3653120 DOI: 10.3389/fonc.2013.00119] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 04/28/2013] [Indexed: 12/17/2022] Open
Abstract
One in four deaths in the United States is cancer-related, and colorectal cancer (CRC) is the second leading cause of cancer-associated deaths. Screening strategies are utilized but have not reduced disease incidence or mortality. In this regard, there is an interest in cancer preventive strategies focusing on lifestyle intervention, where specific etiologic factors involved in cancer initiation, promotion, and progression could be targeted. For example, exposure to dietary carcinogens, such as nitrosamines and polycyclic aromatic hydrocarbons influences colon carcinogenesis. Furthermore, dietary deficiencies could alter sensitivity to genetic damage and influence carcinogen metabolism contributing to CRC. High alcohol consumption increases the risk of mutations including the fact that acetaldehyde, an ethanol metabolite, is classified as a group 1 carcinogen. Tobacco smoke exposure is also a risk factor for cancer development; approximately 20% of CRCs are associated with smoking. Additionally, obese patients have a higher risk of cancer development, which is further supported by the fact that physical activity decreases CRC risk by 55%. Similarly, chronic inflammatory conditions also increase the risk of CRC development. Moreover, the circadian clock alters digestion and regulates other biochemical, physiological, and behavioral processes that could influence CRC. Taken together, colon carcinogenesis involves a number of etiological factors, and therefore, to create effective preventive strategies, molecular targets need to be identified and beleaguered prior to disease progression. With this in mind, the following is a comprehensive review identifying downstream target proteins of the above lifestyle risk factors, which are modulated during colon carcinogenesis and could be targeted for CRC prevention by novel agents including phytochemicals.
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Affiliation(s)
- Molly M Derry
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus Aurora, CO, USA
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Sadik NAH, Shaker OG. Dietary folate suppresses DMH-induced colon carcinogenesis in a rat model and affects DMH-induced expression of four DNA repair enzymes. Nutr Cancer 2012; 64:1196-203. [PMID: 23137028 DOI: 10.1080/01635581.2012.718030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This study investigated the potential role of folate in the dimethylhydrazine (DMH) colon cancer model in male Wistar rats. For induction of colon cancer, group 1 rats were injected subcutaneously with 30 mg DMH/kg body weight weekly for 30 wk. Group 2 received DMH vehicle. Group 3 rats received DMH as in Group 1 but their diet was supplemented with 8 mg folate/kg diet. Group 4 was fed diet supplemented with 8 mg folate/kg diet. Upregulation of DNA damage repair genes Apurinic/apyrimidinic endonuclease 1, X-ray repair complementing defective repair in Chinese hamster cells 5, 8-oxoguanine-DNA glycosylase, and proliferating cell nuclear antigen, associated with a reduction of folic acid level was observed in colons of DMH group. Reductions of these gene upregulations and a significant increase of colonic folic acid level occurred in the DMH group supplemented with folic acid and this group also had significant inhibition of tumor incidence, normal survival rate and histologically nearly normal colonic architecture. It can be concluded that folate supplementation exerts a potent protective effect on rat colon carcinogenesis via significant modulation of DNA repair, providing a mechanism by which it plays a role in the etiology of human cancer.
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Affiliation(s)
- Nermin A H Sadik
- Biochemistry Department, Faculty of Pharmacy, Cairo University, Cairo, Egypt.
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Association of folate intake, dietary habits, smoking and COX-2 promotor -765G>C polymorphism with K-ras mutation in patients with colorectal cancer. J Egypt Natl Canc Inst 2012; 24:115-22. [PMID: 22929917 DOI: 10.1016/j.jnci.2012.05.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Accepted: 05/15/2012] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Understanding the role of environmental and molecular influences on the nature and rate of K-ras mutations in colorectal neoplasms is crucial. COX-2 polymorphisms -765G>C may play a role in carcinogenic processes in combination with specific life-style conditions or dependent on the racial composition of a particular population. If mutational events play an important role in colorectal carcinogenesis sequence, one can hypothesize that modification of these events by life-style or other factors would be a useful prevention strategy. AIM OF WORK To explore the association between K-ras mutation and potential variables known or suspected to be related to the risk of colorectal cancer (CRC) as well as determining the possible modulating effect of the COX-2 polymorphism, -765G>C. SUBJECTS AND METHODS The study was conducted on 80 patients with colorectal cancer from Tropical Medicine and Gastrointestinal Tract endoscopy Departments and those attending clinic of the National Cancer Institute, Cairo University during the period extending from April 2009 to March 2010. Full history taking with emphasis on the risk factors of interest, namely age, sex, family history, smoking and dietary history. Serum CEA and CA19-9, RBCs folic acid and occult blood in stool were done to all samples. K-ras protooncogene mutation at codon 12 (exon 1) and cyclooxygenase 2 (COX-2) -765G>C polymorphism were determined by PCR-RFLP. RESULTS The K-ras mutation was positive in 23 (28.7%) patients. COX-2 polymorphism revealed GG in 62.5%, GC in 26.2 % and CC genotype was found in 11.3 % of cases. The mean red blood cell folic acid level was lower in the K-ras positive group (100.96±51.3 ng/ml) than the negative group (216.6±166.4 ng/ml), (P<0.01). Higher folate levels were found in males than females (median=173 ng/ml and 85 ng/ml; respectively, P=0.002) with adjusted odds ratio (OR) of 0.984. Only, the RBCs folate (P=0.0018) followed by gender (P=0.036) contributed significantly in the discrimination between patients prone to develop K-ras mutation and those who are not. CONCLUSION RBC folic acid was significantly deficient in CRC (colorectal cancer) patients with K-ras mutations in comparison with CRC patients free of the mutations, suggesting that folic acid may be a risk factor for K-ras mutation development.
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Romagnolo DF, Milner JA. Opportunities and challenges for nutritional proteomics in cancer prevention. J Nutr 2012; 142:1360S-9S. [PMID: 22649262 DOI: 10.3945/jn.111.151803] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Knowledge gaps persist about the efficacy of cancer prevention strategies based on dietary food components. Adaptations to nutrient supply are executed through tuning of multiple protein networks that include transcription factors, histones, modifying enzymes, translation factors, membrane and nuclear receptors, and secreted proteins. However, the simultaneous quantitative and qualitative measurement of all proteins that regulate cancer processes is not practical using traditional protein methodologies. Proteomics offers an attractive opportunity to fill this knowledge gap and unravel the effects of dietary components on protein networks that impinge on cancer. The articles presented in this supplement are from talks proffered in the "Nutrition Proteomics and Cancer Prevention" session at the American Institute for Cancer Research Annual Research Conference on Food, Nutrition, Physical Activity and Cancer held in Washington, DC on October 21 and 22, 2010. Recent advances in MS technologies suggest that studies in nutrition and cancer prevention may benefit from the adoption of proteomic tools to elucidate the impact on biological processes that govern the transition from normal to malignant phenotype; to identify protein changes that determine both positive and negative responses to food components; to assess how protein networks mediate dose-, time-, and tissue-dependent responses to food components; and, finally, for predicting responders and nonresponders. However, both the limited accessibility to proteomic technologies and research funding appear to be hampering the routine adoption of proteomic tools in nutrition and cancer prevention research.
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Affiliation(s)
- Donato F Romagnolo
- Department of Nutritional Sciences and The University of Arizona Cancer Center, The University of Arizona, Tucson, AZ, USA.
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Bestwick CS, Ralton LD, Milne L, Kong Thoo Lin P, Duthie SJ. The influence of bisnaphthalimidopropyl polyamines on DNA instability and repair in Caco-2 colon epithelial cells. Cell Biol Toxicol 2011; 27:455-63. [PMID: 21842340 DOI: 10.1007/s10565-011-9199-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Accepted: 08/02/2011] [Indexed: 12/11/2022]
Abstract
Bisnaphthalimido compounds bis-intercalate to DNA via the major groove and are potentially potent cancer therapeutics. Previously, we incorporated natural polyamines as linkers connecting the two naphthalimido ring moieties to create a series of soluble bisnaphthalimidopropyl polyamines (BNIPPs). Here, extending earlier work on bisnaphthalimidopropylspermidine (BNIPSpd)-induced apoptosis in colon adenocarcinoma Caco-2 cells, we compare the cytotoxicity and genotoxicity of BNIPSpd relative to the spermine and oxaspermine derivatives, bisnaphthalimidopropylspermine (BNIPSpm) and bisnaphthalimidopropyloxaspermine (BNIPOSpm). The order of cytotoxicity after 24 h was BNIPSpd (IC(50) = 0.47 μM) > BNIPSpm (IC(50) = 10.04 μM) > BNIPOSpm (IC(50) >50 μM). After a 72-h BNIPOSpm exposure, an IC(50) = 10.25 μM was achieved. With 4-h exposure to BNIPSpd or BNIPSpm or 12-h exposure to BNIPOSpm, concentrations ≥1 μM induced a significant dose-dependent increase in DNA damage as measured by alkaline single-cell gel electrophoresis. The longer incubation times required for BNIPOSpm to induce DNA strand breaks reflect a slower rate of BNIPOSpm cellular distribution as monitored via BNIPP fluorescence within the cells. Moreover, exposure to a non-genotoxic concentration of BNIPSpd, BNIPSpm (0.1 μM for 4 h) or BNIPOSpm (0.1 μM for 12 h) induced a significant decrease in repair of oxidative DNA damage induced by hydrogen peroxide. In conclusion, BNIPP exposure in Caco-2 cells is associated with significant induction of DNA damage and inhibition of DNA repair at non-genotoxic concentrations. The latter is a novel consequence of BNIPP-cell interactions which adds to the spectrum of therapeutically relevant activities that may be exploited for the design and development of naphthalimide-based therapeutics.
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Hannibal L, DiBello PM, Yu M, Miller A, Wang S, Willard B, Rosenblatt DS, Jacobsen DW. The MMACHC proteome: hallmarks of functional cobalamin deficiency in humans. Mol Genet Metab 2011; 103:226-39. [PMID: 21497120 PMCID: PMC3110603 DOI: 10.1016/j.ymgme.2011.03.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2011] [Revised: 03/08/2011] [Accepted: 03/08/2011] [Indexed: 12/13/2022]
Abstract
Cobalamin (Cbl, B(12)) is an essential micronutrient required to fulfill the enzymatic reactions of cytosolic methylcobalamin-dependent methionine synthase and mitochondrial adenosylcobalamin-dependent methylmalonyl-CoA mutase. Mutations in the MMACHC gene (cblC complementation group) disrupt processing of the upper-axial ligand of newly internalized cobalamins, leading to functional deficiency of the vitamin. Patients with cblC disease present with both hyperhomocysteinemia and methylmalonic acidemia, cognitive dysfunction, and megaloblastic anemia. In the present study we show that cultured skin fibroblasts from cblC patients export increased levels of both homocysteine and methylmalonic acid compared to control skin fibroblasts, and that they also have decreased levels of total intracellular folates. This is consistent with the clinical phenotype of functional cobalamin deficiency in vivo. The protein changes that accompany human functional Cbl deficiency are unknown. The proteome of control and cblC fibroblasts was quantitatively examined by two dimensional difference in-gel electrophoresis (2D-DIGE) and liquid chromatography-electrospray ionization-mass spectrometry (LC/ESI/MS). Major changes were observed in the expression levels of proteins involved in cytoskeleton organization and assembly, the neurological system and cell signaling. Pathway analysis of the differentially expressed proteins demonstrated strong associations with neurological disorders, muscular and skeletal disorders, and cardiovascular diseases in the cblC mutant cell lines. Supplementation of the cell cultures with hydroxocobalamin did not restore the cblC proteome to the patterns of expression observed in control cells. These results concur with the observed phenotype of patients with the cblC disorder and their sometimes poor response to treatment with hydroxocobalamin. Our findings could be valuable for designing alternative therapies to alleviate the clinical manifestation of the cblC disorder, as some of the protein changes detected in our study are common hallmarks of known pathologies such as Alzheimer's and Parkinson's diseases as well as muscular dystrophies.
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Affiliation(s)
- Luciana Hannibal
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic Cleveland, OH 44195
- School of Biomedical Sciences, Kent State University, Kent, OH 44242
- Address correspondence to: Luciana Hannibal, Ph.D., Department of Pathobiology, NC2-104, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Ave., Cleveland, OH 44195, Tel: 216-445-9761, Fax: 216-636-0104, , or Donald W. Jacobsen, Ph.D., Department of Cell Biology, NC-10, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Ave, Cleveland, OH 44195, Tel: 216-444-8340, Fax: 216-444-9404,
| | - Patricia M. DiBello
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic Cleveland, OH 44195
| | - Michelle Yu
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic Cleveland, OH 44195
| | - Abby Miller
- Department of Clinical Pathology, Cleveland Clinic, Cleveland, OH 44195
| | - Sihe Wang
- Department of Clinical Pathology, Cleveland Clinic, Cleveland, OH 44195
| | - Belinda Willard
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic Cleveland, OH 44195
| | | | - Donald W. Jacobsen
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic Cleveland, OH 44195
- School of Biomedical Sciences, Kent State University, Kent, OH 44242
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH 44106
- Address correspondence to: Luciana Hannibal, Ph.D., Department of Pathobiology, NC2-104, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Ave., Cleveland, OH 44195, Tel: 216-445-9761, Fax: 216-636-0104, , or Donald W. Jacobsen, Ph.D., Department of Cell Biology, NC-10, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Ave, Cleveland, OH 44195, Tel: 216-444-8340, Fax: 216-444-9404,
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Maldonado E, Murillo J, Barrio C, del Río A, Pérez-Miguelsanz J, López-Gordillo Y, Partearroyo T, Paradas I, Maestro C, Martínez-Sanz E, Varela-Moreiras G, Martínez-Álvarez C. Occurrence of cleft-palate and alteration of Tgf-β(3) expression and the mechanisms leading to palatal fusion in mice following dietary folic-acid deficiency. Cells Tissues Organs 2011; 194:406-20. [PMID: 21293104 DOI: 10.1159/000323213] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/30/2010] [Indexed: 02/02/2023] Open
Abstract
Folic acid (FA) is essential for numerous bodily functions. Its decrease during pregnancy has been associated with an increased risk of congenital malformations in the progeny. The relationship between FA deficiency and the appearance of cleft palate (CP) is controversial, and little information exists on a possible effect of FA on palate development. We investigated the effect of a 2-8 weeks' induced FA deficiency in female mice on the development of CP in their progeny as well as the mechanisms leading to palatal fusion, i.e. cell proliferation, cell death, and palatal-shelf adhesion and fusion. We showed that an 8 weeks' maternal FA deficiency caused complete CP in the fetuses although a 2 weeks' maternal FA deficiency was enough to alter all the mechanisms analyzed. Since transforming growth factor-β(3) (TGF-β(3)) is crucial for palatal fusion and since most of the mechanisms impaired by FA deficiency were also observed in the palates of Tgf-β(3)null mutant mice, we investigated the presence of TGF-β(3) mRNA, its protein and phospho-SMAD2 in FA-deficient (FAD) mouse palates. Our results evidenced a large reduction in Tgf-β(3) expression in palates of embryos of dams fed an FAD diet for 8 weeks; Tgf-β(3) expression was less reduced in palates of embryos of dams fed an FAD diet for 2 weeks. Addition of TGF-β(3) to palatal-shelf cultures of embryos of dams fed an FAD diet for 2 weeks normalized all the altered mechanisms. Thus, an insufficient folate status may be a risk factor for the development of CP in mice, and exogenous TGF-β(3) compensates this deficit in vitro.
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Affiliation(s)
- Estela Maldonado
- Departamento de Anatomía y Embriología Humana I, Facultad de Odontología, Universidad Complutense, Madrid, Spain
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Duthie SJ. Folate and cancer: how DNA damage, repair and methylation impact on colon carcinogenesis. J Inherit Metab Dis 2011; 34:101-9. [PMID: 20544289 DOI: 10.1007/s10545-010-9128-0] [Citation(s) in RCA: 177] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Revised: 02/24/2010] [Accepted: 05/05/2010] [Indexed: 12/18/2022]
Abstract
Inappropriate diet may contribute to one third of cancer deaths. Folates, a group of water-soluble B vitamins present in high concentrations in green, leafy vegetables, maintain DNA stability through their ability to donate one-carbon units for cellular metabolism. Folate deficiency has been implicated in the development of several cancers, including cancer of the colorectum, breast, ovary, pancreas, brain, lung and cervix. Generally, data from the majority of human studies suggest that people who habitually consume the highest level of folate, or with the highest blood folate concentrations, have a significantly reduced risk of developing colon polyps or cancer. However, an entirely protective role for folate against carcinogenesis has been questioned, and recent data indicate that an excessive intake of synthetic folic acid (from high-dose supplements or fortified foods) may increase human cancers by accelerating growth of precancerous lesions. Nonetheless, on balance, evidence from the majority of human studies indicates that dietary folate is genoprotective against colon cancer. Suboptimal folate status in humans is widespread. Folate maintains genomic stability by regulating DNA biosynthesis, repair and methylation. Folate deficiency induces and accelerates carcinogenesis by perturbing each of these processes. This review presents recent evidence describing how these mechanisms act, and interact, to modify colon cancer risk.
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Affiliation(s)
- Susan J Duthie
- Nutrition and Epigenetics Group, Division of Vascular Health, Rowett Institute of Nutrition and Health, University of Aberdeen, Bucksburn, Aberdeen, UK.
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Abstract
Epigenetic changes are inherited alterations in DNA that affect gene expression and function without altering the DNA sequence. DNA methylation is one epigenetic process implicated in human disease that is influenced by diet. DNA methylation involves addition of a 1-C moiety to cytosine groups in DNA. Methylated genes are not transcribed or are transcribed at a reduced rate. Global under-methylation (hypomethylation) and site-specific over-methylation (hypermethylation) are common features of human tumours. DNA hypomethylation, leading to increased expression of specific proto-oncogenes (e.g. genes involved in proliferation or metastasis) can increase the risk of cancer as can hypermethylation and reduced expression of tumour suppressor (TS) genes (e.g. DNA repair genes). DNA methyltransferases (DNMT), together with the methyl donor S-adenosylmethionine (SAM), facilitate DNA methylation. Abnormal DNA methylation is implicated not only in the development of human cancer but also in CVD. Polyphenols, a group of phytochemicals consumed in significant amounts in the human diet, effect risk of cancer. Flavonoids from tea, soft fruits and soya are potent inhibitors of DNMT in vitro, capable of reversing hypermethylation and reactivating TS genes. Folates, a group of water-soluble B vitamins found in high concentration in green leafy vegetables, regulate DNA methylation through their ability to generate SAM. People who habitually consume the lowest level of folate or with the lowest blood folate concentrations have a significantly increased risk of developing several cancers and CVD. This review describes how flavonoids and folates in the human diet alter DNA methylation and may modify the risk of human colon cancer and CVD.
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Duthie SJ, Horgan G, de Roos B, Rucklidge G, Reid M, Duncan G, Pirie L, Basten GP, Powers HJ. Blood folate status and expression of proteins involved in immune function, inflammation, and coagulation: biochemical and proteomic changes in the plasma of humans in response to long-term synthetic folic acid supplementation. J Proteome Res 2010; 9:1941-50. [PMID: 20143872 DOI: 10.1021/pr901103n] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We used plasma proteomics to identify human proteins responsive to folate status. Plasma was collected from subjects treated with placebo or 1.2 mg of folic acid daily for 12 weeks in a randomized controlled trial. Homocysteine and folate were measured by immunoassay and uracil misincorporation by electrophoresis. The plasma proteome was assessed by 2-D gel electrophoresis, and proteins were identified by LC MS/MS. 5-methylTHF increased 5-fold (P = 0.000003) in response to intervention. Red cell folate doubled (P = 0.013), and lymphocyte folate increased 44% (P = 0.0001). Hcy and uracil dropped 22% (P = 0.0005) and 25% (P = 0.05), respectively. ApoE A-1, alpha-1-antichymotrypsin, antithrombin, and serum amyloid P were downregulated, while albumin, IgM C, and complement C3 were upregulated (P < 0.05). More than 60 proteins were significantly associated with folate pre- and postintervention (P < 0.01). These were categorized into metabolic pathways related to complement fixation (e.g., C1, C3, C4, Factor H, Factor 1, Factor B, clusterin), coagulation (e.g., antithrombin, alpha-1-antitrypsin, kininogen) and mineral transport (e.g., transthyretin, haptoglobin, ceruloplasmin). Low folate status pre- and post-treatment were associated with lower levels of proteins involved in activation and regulation of immune function and coagulation. Supplementation with synthetic folic acid increased expression of these proteins but did not substantially disrupt the balance of these pathways.
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Affiliation(s)
- Susan J Duthie
- Aberdeen University Rowett Institute of Nutrition and Health, Aberdeen, U.K.
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26
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Ventrella-Lucente LF, Unnikrishnan A, Pilling AB, Patel HV, Kushwaha D, Dombkowski AA, Schmelz EM, Cabelof DC, Heydari AR. Folate deficiency provides protection against colon carcinogenesis in DNA polymerase beta haploinsufficient mice. J Biol Chem 2010; 285:19246-58. [PMID: 20404327 DOI: 10.1074/jbc.m109.069807] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Aging and DNA polymerase beta deficiency (beta-pol(+/-)) interact to accelerate the development of malignant lymphomas and adenocarcinoma and increase tumor bearing load in mice. Folate deficiency (FD) has been shown to induce DNA damage repaired via the base excision repair (BER) pathway. We anticipated that FD and BER deficiency would interact to accelerate aberrant crypt foci (ACF) formation and tumor development in beta-pol haploinsufficient animals. FD resulted in a significant increase in ACF formation in wild type (WT) animals exposed to 1,2-dimethylhydrazine, a known colon and liver carcinogen; however, FD reduced development of ACF in beta-pol haploinsufficient mice. Prolonged feeding of the FD diet resulted in advanced ACF formation and liver tumors in wild type mice. However, FD attenuated onset and progression of ACF and prevented liver tumorigenesis in beta-pol haploinsufficient mice, i.e. FD provided protection against tumorigenesis in a BER-deficient environment in all tissues where 1,2-dimethylhydrazine exerts its damage. Here we show a distinct down-regulation in DNA repair pathways, e.g. BER, nucleotide excision repair, and mismatch repair, and decline in cell proliferation, as well as an up-regulation in poly(ADP-ribose) polymerase, proapoptotic genes, and apoptosis in colons of FD beta-pol haploinsufficient mice.
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Affiliation(s)
- Lisa F Ventrella-Lucente
- Department of Nutrition and Food, Science College of Liberal Arts and Sciences, School of Medicine, Wayne State University, Detroit, Michigan 48202, USA
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Duthie SJ, Grant G, Pirie LP, Watson AJ, Margison GP. Folate deficiency alters hepatic and colon MGMT and OGG-1 DNA repair protein expression in rats but has no effect on genome-wide DNA methylation. Cancer Prev Res (Phila) 2010; 3:92-100. [PMID: 20051376 DOI: 10.1158/1940-6207.capr-09-0231] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Folate deficiency is implicated in human colon cancer. The effects of feeding rats a folate-deficient diet for 24 weeks on DNA damage (8-oxo-7,8-dihydroguanine), DNA repair [O(6)-methylguanine-DNA methyltransferase (MGMT) and 8-oxoguanine-DNA glycosylase (OGG-1) activity], and epigenetic parameters (genome-wide cytosine methylation and indices of cellular methylation status) were investigated. Relative to control diet, the folate-deficient diet resulted in significantly reduced levels of serum ( approximately 80%; P < 0.0001), whole blood ( approximately 40%; P < 0.0001), and tissue folate (between 25% and 60% depending on the tissue sampled; P < 0.05); increased plasma total homocysteine ( approximately 35%; P < 0.05); and decreased S-adenosylmethionine to S-adenosylhomocysteine concentrations ( approximately 11%; P < 0.05). There was no significant change in the levels of 5-methyldeoxycytidine in liver or colon DNA, nor in the activity of liver DNA cytosine methyltransferase. However, there were significant increases in 8-oxo-7,8-dihydroguanine (P < 0.001) in lymphocyte DNA and in levels of the DNA repair proteins OGG-1 ( approximately 27%; P < 0.03) and MGMT ( approximately 25%; P < 0.003) in the liver, but not in the colon. This may reflect the ability of the liver, but not the colon, to upregulate DNA repair enzymes in response to either elevated DNA damage or an imbalance in the nucleotide precursor pool. These results show that folate deficiency can significantly modulate DNA damage and DNA repair, providing mechanisms by which it plays a role in the etiology of human cancer. We speculate that the inability of colon tissue to respond to folate deficiency occurs in humans and may increase the potential for malignant transformation.
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Affiliation(s)
- Susan J Duthie
- Rowett Institute of Nutrition and Health, University of Aberdeen, United Kingdom.
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Tunbridge EM. The catechol-O-methyltransferase gene: its regulation and polymorphisms. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2010; 95:7-27. [PMID: 21095457 DOI: 10.1016/b978-0-12-381326-8.00002-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The catechol-O-methyltransferase (COMT) gene is of significant interest to neuroscience, due to its role in modulating dopamine function. COMT is dynamically regulated; its expression is altered during normal brain development and in response to environmental stimuli. In many cases the underlying molecular basis for these effects is unknown; however, in some cases (e.g., estrogenic regulation in the case of sex differences) regulatory mechanisms have been identified. COMT contains several functional polymorphisms and haplotypes, including the well-studied Val158Met polymorphism. Here I review the regulation of COMT and the functional polymorphisms within its sequence with respect to brain function.
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Ikonomou G, Samiotaki M, Panayotou G. Proteomic methodologies and their application in colorectal cancer research. Crit Rev Clin Lab Sci 2009; 46:319-42. [DOI: 10.3109/10408360903375277] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Mathers JC. Folate intake and bowel cancer risk. GENES & NUTRITION 2009; 4:173-8. [PMID: 19499262 PMCID: PMC2745742 DOI: 10.1007/s12263-009-0126-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Accepted: 05/14/2009] [Indexed: 12/21/2022]
Abstract
Folate is a B vitamin required for one-carbon transfer reactions including methylation of cell macromolecules including DNA and synthesis of the purines adenosine and guanosine and the pyrimidine thymidine. Epidemiological evidence suggests that diets providing higher amounts of folates lower the risk of colo-rectal cancer (CRC) and these observations are supported by plausible biological mechanisms. Inadequate folate supply results in DNA damage through (a) the incorporation of uracil (in place of thymidine) into DNA and subsequent unsuccessful attempts at DNA repair and (b) aberrant patterns of DNA methylation. However, human intervention studies using relatively large doses (500-5,000 mug/day) of folic acid (a synthetic form of folate) have provided no evidence of benefit in terms of adenoma recurrence. Indeed, there is some evidence of potential harm in increased risk of prostate cancer. Possible reasons for the apparent divergence in findings from the observational and intervention studies include the use of (unphysiologically) large doses of folic acid in the intervention studies whereas smaller intakes of food folates appeared to offer "protection" against CRC in case-control and prospective cohort studies. With intakes of folic acid greater than 400 mug/day, unmetabolised folic acid appears in peripheral blood and there are suggestions that this folic acid may have adverse effects e.g. reduced cytotoxicity of Natural Killer cells. Until the benefit-risk relationship associated with mandatory fortification with folic acid has been clarified (and, in particular, the possible risk of inducing extra cases of bowel or other cancer), it would seem wise to delay further mandatory folic acid fortification.
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Affiliation(s)
- John C Mathers
- Human Nutrition Research Centre, Institute for Ageing and Health, Newcastle University, William Leech Building, Framlington Place, Newcastle on Tyne, NE2 4HH, UK,
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Krasnikov BF, Chien CH, Nostramo R, Pinto JT, Nieves E, Callaway M, Sun J, Huebner K, Cooper AJL. Identification of the putative tumor suppressor Nit2 as omega-amidase, an enzyme metabolically linked to glutamine and asparagine transamination. Biochimie 2009; 91:1072-80. [PMID: 19595734 DOI: 10.1016/j.biochi.2009.07.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Accepted: 07/03/2009] [Indexed: 11/25/2022]
Abstract
The present report identifies the enzymatic substrates of a member of the mammalian nitrilase-like (Nit) family. Nit2, which is widely distributed in nature, has been suggested to be a tumor suppressor protein. The protein was assumed to be an amidase based on sequence homology to other amidases and on the presence of a putative amidase-like active site. This assumption was recently confirmed by the publication of the crystal structure of mouse Nit2. However, the in vivo substrates were not previously identified. Here we report that rat liver Nit2 is omega-amidodicarboxylate amidohydrolase (E.C. 3.5.1.3; abbreviated omega-amidase), a ubiquitously expressed enzyme that catalyzes a variety of amidase, transamidase, esterase and transesterification reactions. The in vivo amidase substrates are alpha-ketoglutaramate and alpha-ketosuccinamate, generated by transamination of glutamine and asparagine, respectively. Glutamine transaminases serve to salvage a number of alpha-keto acids generated through non-specific transamination reactions (particularly those of the essential amino acids). Asparagine transamination appears to be useful in mitochondrial metabolism and in photorespiration. Glutamine transaminases play a particularly important role in transaminating alpha-keto-gamma-methiolbutyrate, a key component of the methionine salvage pathway. Some evidence suggests that excess alpha-ketoglutaramate may be neurotoxic. Moreover, alpha-ketosuccinamate is unstable and is readily converted to a number of hetero-aromatic compounds that may be toxic. Thus, an important role of omega-amidase is to remove potentially toxic intermediates by converting alpha-ketoglutaramate and alpha-ketosuccinamate to biologically useful alpha-ketoglutarate and oxaloacetate, respectively. Despite its importance in nitrogen and sulfur metabolism, the biochemical significance of omega-amidase has been largely overlooked. Our report may provide clues regarding the nature of the biological amidase substrate(s) of Nit1 (another member of the Nit family), which is a well-established tumor suppressor protein), and emphasizes a) the crucial role of Nit2 in nitrogen and sulfur metabolism, and b) the possible link of Nit2 to cancer biology.
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Affiliation(s)
- Boris F Krasnikov
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, USA.
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