1
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Sun A, Park P, Cole L, Vaidya H, Maegawa S, Keith K, Calendo G, Madzo J, Jelinek J, Jobin C, Issa JPJ. Non-pathogenic microbiota accelerate age-related CpG Island methylation in colonic mucosa. Epigenetics 2023; 18:2160568. [PMID: 36572998 PMCID: PMC9980687 DOI: 10.1080/15592294.2022.2160568] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 11/11/2022] [Indexed: 12/28/2022] Open
Abstract
DNA methylation is an epigenetic process altered in cancer and ageing. Age-related methylation drift can be used to estimate lifespan and can be influenced by extrinsic factors such as diet. Here, we report that non-pathogenic microbiota accelerate age-related methylation drift in the colon when compared with germ-free mice. DNA methylation analyses showed that microbiota and IL10KO were associated with changes in 5% and 4.1% of CpG sites, while mice with both factors had 18% alterations. Microbiota, IL10KO, and their combination altered 0.4%, 0.4%, and 4% of CpG island methylation, respectively. These are comparable to what is seen in colon cancer. Ageing changes were accelerated in the IL10KO mice with microbiota, and the affected genes were more likely to be altered in colon cancer. Thus, the microbiota affect DNA methylation of the colon in patterns reminiscent of what is observed in ageing and colorectal cancer.
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Affiliation(s)
- Ang Sun
- Fels Cancer Institute for Personalized Medicine, Temple University School of Medicine, Philadelphia, PA, United States
| | - Pyounghwa Park
- Fels Cancer Institute for Personalized Medicine, Temple University School of Medicine, Philadelphia, PA, United States
- Coriell Institute for Medical Research, Camden, NJ, United States
| | - Lauren Cole
- Fels Cancer Institute for Personalized Medicine, Temple University School of Medicine, Philadelphia, PA, United States
| | - Himani Vaidya
- Fels Cancer Institute for Personalized Medicine, Temple University School of Medicine, Philadelphia, PA, United States
- Coriell Institute for Medical Research, Camden, NJ, United States
| | - Shinji Maegawa
- Fels Cancer Institute for Personalized Medicine, Temple University School of Medicine, Philadelphia, PA, United States
- Research Department of Pediatrics, University of Texas, MD Anderson Cancer Center Department of Pediatrics, University of Texas, MD Anderson Cancer CenterHouston, TX, USA
| | - Kelsey Keith
- Fels Cancer Institute for Personalized Medicine, Temple University School of Medicine, Philadelphia, PA, United States
- Coriell Institute for Medical Research, Camden, NJ, United States
| | - Gennaro Calendo
- Coriell Institute for Medical Research, Camden, NJ, United States
| | - Jozef Madzo
- Fels Cancer Institute for Personalized Medicine, Temple University School of Medicine, Philadelphia, PA, United States
- Coriell Institute for Medical Research, Camden, NJ, United States
| | - Jaroslav Jelinek
- Fels Cancer Institute for Personalized Medicine, Temple University School of Medicine, Philadelphia, PA, United States
- Coriell Institute for Medical Research, Camden, NJ, United States
| | - Christian Jobin
- Department of Medicine, Division of Gastroenterology, Hepatology, and Nutrition, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Jean-Pierre J. Issa
- Fels Cancer Institute for Personalized Medicine, Temple University School of Medicine, Philadelphia, PA, United States
- Coriell Institute for Medical Research, Camden, NJ, United States
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2
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Iqbal W, Zhou W. Computational Methods for Single-cell DNA Methylome Analysis. GENOMICS, PROTEOMICS & BIOINFORMATICS 2023; 21:48-66. [PMID: 35718270 PMCID: PMC10372927 DOI: 10.1016/j.gpb.2022.05.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 04/28/2022] [Accepted: 05/10/2022] [Indexed: 11/19/2022]
Abstract
Dissecting intercellular epigenetic differences is key to understanding tissue heterogeneity. Recent advances in single-cell DNA methylome profiling have presented opportunities to resolve this heterogeneity at the maximum resolution. While these advances enable us to explore frontiers of chromatin biology and better understand cell lineage relationships, they pose new challenges in data processing and interpretation. This review surveys the current state of computational tools developed for single-cell DNA methylome data analysis. We discuss critical components of single-cell DNA methylome data analysis, including data preprocessing, quality control, imputation, dimensionality reduction, cell clustering, supervised cell annotation, cell lineage reconstruction, gene activity scoring, and integration with transcriptome data. We also highlight unique aspects of single-cell DNA methylome data analysis and discuss how techniques common to other single-cell omics data analyses can be adapted to analyze DNA methylomes. Finally, we discuss existing challenges and opportunities for future development.
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Affiliation(s)
- Waleed Iqbal
- Center for Computational and Genomic Medicine, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Wanding Zhou
- Center for Computational and Genomic Medicine, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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3
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Aleotti V, Catoni C, Poggiana C, Rosato A, Facchinetti A, Scaini MC. Methylation Markers in Cutaneous Melanoma: Unravelling the Potential Utility of Their Tracking by Liquid Biopsy. Cancers (Basel) 2021; 13:6217. [PMID: 34944843 PMCID: PMC8699653 DOI: 10.3390/cancers13246217] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/02/2021] [Accepted: 12/08/2021] [Indexed: 01/19/2023] Open
Abstract
Malignant melanoma is the most serious, life-threatening form of all dermatologic diseases, with a poor prognosis in the presence of metastases and advanced disease. Despite recent advances in targeted therapy and immunotherapy, there is still a critical need for a better understanding of the fundamental mechanisms behind melanoma progression and resistance onset. Recent advances in genome-wide methylation methods have revealed that aberrant changes in the pattern of DNA methylation play an important role in many aspects of cancer progression, including cell proliferation and migration, evasion of cell death, invasion, and metastasization. The purpose of the current review was to gather evidence regarding the usefulness of DNA methylation tracking in liquid biopsy as a potential biomarker in melanoma. We investigated the key genes and signal transduction pathways that have been found to be altered epigenetically in melanoma. We then highlighted the circulating tumor components present in blood, including circulating melanoma cells (CMC), circulating tumor DNA (ctDNA), and tumor-derived extracellular vesicles (EVs), as a valuable source for identifying relevant aberrations in DNA methylation. Finally, we focused on DNA methylation signatures as a marker for tracking response to therapy and resistance, thus facilitating personalized medicine and decision-making in the treatment of melanoma patients.
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Affiliation(s)
- Valentina Aleotti
- Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCCS, 35128 Padua, Italy; (V.A.); (C.C.); (A.F.); (M.C.S.)
| | - Cristina Catoni
- Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCCS, 35128 Padua, Italy; (V.A.); (C.C.); (A.F.); (M.C.S.)
| | - Cristina Poggiana
- Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCCS, 35128 Padua, Italy; (V.A.); (C.C.); (A.F.); (M.C.S.)
| | - Antonio Rosato
- Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCCS, 35128 Padua, Italy; (V.A.); (C.C.); (A.F.); (M.C.S.)
- Department of Surgery, Oncology and Gastroenterology, Oncology and Immunology Section, University of Padua, 35128 Padua, Italy
| | - Antonella Facchinetti
- Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCCS, 35128 Padua, Italy; (V.A.); (C.C.); (A.F.); (M.C.S.)
- Department of Surgery, Oncology and Gastroenterology, Oncology and Immunology Section, University of Padua, 35128 Padua, Italy
| | - Maria Chiara Scaini
- Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCCS, 35128 Padua, Italy; (V.A.); (C.C.); (A.F.); (M.C.S.)
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4
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Yalcin D, Otu HH. An Unbiased Predictive Model to Detect DNA Methylation Propensity of CpG Islands in the Human Genome. Curr Bioinform 2021. [DOI: 10.2174/1574893615999200724145835] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
Epigenetic repression mechanisms play an important role in gene
regulation, specifically in cancer development. In many cases, a CpG island’s (CGI) susceptibility
or resistance to methylation is shown to be contributed by local DNA sequence features.
Objective:
To develop unbiased machine learning models–individually and combined for different
biological features–that predict the methylation propensity of a CGI.
Methods:
We developed our model consisting of CGI sequence features on a dataset of 75
sequences (28 prone, 47 resistant) representing a genome-wide methylation structure. We tested
our model on two independent datasets that are chromosome (132 sequences) and disease (70
sequences) specific.
Results:
We provided improvements in prediction accuracy over previous models. Our results
indicate that combined features better predict the methylation propensity of a CGI (area under the
curve (AUC) ~0.81). Our global methylation classifier performs well on independent datasets
reaching an AUC of ~0.82 for the complete model and an AUC of ~0.88 for the model using select
sequences that better represent their classes in the training set. We report certain de novo motifs
and transcription factor binding site (TFBS) motifs that are consistently better in separating prone
and resistant CGIs.
Conclusion:
Predictive models for the methylation propensity of CGIs lead to a better
understanding of disease mechanisms and can be used to classify genes based on their tendency to
contain methylation prone CGIs, which may lead to preventative treatment strategies. MATLAB®
and Python™ scripts used for model building, prediction, and downstream analyses are available
at https://github.com/dicleyalcin/methylProp_predictor.
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Affiliation(s)
- Dicle Yalcin
- Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE, 68588, United States
| | - Hasan H. Otu
- Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE, 68588, United States
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5
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Bell CG, Lowe R, Adams PD, Baccarelli AA, Beck S, Bell JT, Christensen BC, Gladyshev VN, Heijmans BT, Horvath S, Ideker T, Issa JPJ, Kelsey KT, Marioni RE, Reik W, Relton CL, Schalkwyk LC, Teschendorff AE, Wagner W, Zhang K, Rakyan VK. DNA methylation aging clocks: challenges and recommendations. Genome Biol 2019; 20:249. [PMID: 31767039 PMCID: PMC6876109 DOI: 10.1186/s13059-019-1824-y] [Citation(s) in RCA: 455] [Impact Index Per Article: 91.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 09/16/2019] [Indexed: 12/15/2022] Open
Abstract
Epigenetic clocks comprise a set of CpG sites whose DNA methylation levels measure subject age. These clocks are acknowledged as a highly accurate molecular correlate of chronological age in humans and other vertebrates. Also, extensive research is aimed at their potential to quantify biological aging rates and test longevity or rejuvenating interventions. Here, we discuss key challenges to understand clock mechanisms and biomarker utility. This requires dissecting the drivers and regulators of age-related changes in single-cell, tissue- and disease-specific models, as well as exploring other epigenomic marks, longitudinal and diverse population studies, and non-human models. We also highlight important ethical issues in forensic age determination and predicting the trajectory of biological aging in an individual.
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Affiliation(s)
- Christopher G Bell
- William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
| | - Robert Lowe
- The Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
| | - Peter D Adams
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.
- Beatson Institute for Cancer Research and University of Glasgow, Glasgow, UK.
| | - Andrea A Baccarelli
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA.
| | - Stephan Beck
- Medical Genomics, Paul O'Gorman Building, UCL Cancer Institute, University College London, London, UK.
| | - Jordana T Bell
- Department of Twin Research and Genetic Epidemiology, King's College London, London, UK.
| | - Brock C Christensen
- Department of Epidemiology, Geisel School of Medicine, Dartmouth College, Lebanon, NH, USA.
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth College, Lebanon, NH, USA.
- Department of Community and Family Medicine, Geisel School of Medicine, Dartmouth College, Lebanon, NH, USA.
| | - Vadim N Gladyshev
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
| | - Bastiaan T Heijmans
- Molecular Epidemiology, Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, the Netherlands.
| | - Steve Horvath
- Department of Human Genetics, Gonda Research Center, David Geffen School of Medicine, Los Angeles, CA, USA.
- Department of Biostatistics, School of Public Health, University of California-Los Angeles, Los Angeles, CA, USA.
| | - Trey Ideker
- San Diego Center for Systems Biology, University of California-San Diego, San Diego, CA, USA.
| | - Jean-Pierre J Issa
- Fels Institute for Cancer Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA.
| | - Karl T Kelsey
- Department of Epidemiology, Brown University, Providence, RI, USA.
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, USA.
| | - Riccardo E Marioni
- Centre for Genomic and Experimental Medicine, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK.
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK.
| | - Wolf Reik
- Epigenetics Programme, The Babraham Institute, Cambridge, UK.
- The Wellcome Trust Sanger Institute, Cambridge, UK.
| | - Caroline L Relton
- Medical Research Council Integrative Epidemiology Unit (MRC IEU), School of Social and Community Medicine, University of Bristol, Bristol, UK.
| | | | - Andrew E Teschendorff
- CAS Key Laboratory of Computational Biology, CAS-MPG Partner Institute for Computational Biology, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, 200031, China.
- UCL Cancer Institute, Paul O'Gorman Building, University College London, 72 Huntley Street, London, WC1E 6BT, UK.
| | - Wolfgang Wagner
- Helmholtz-Institute for Biomedical Engineering, Stem Cell Biology and Cellular Engineering, RWTH Aachen Faculty of Medicine, Aachen, Germany.
| | - Kang Zhang
- Faculty of Medicine, Macau University of Science and Technology, Taipa, Macau.
| | - Vardhman K Rakyan
- The Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
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6
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Kushwaha PP, Gupta S, Singh AK, Kumar S. Emerging Role of Migration and Invasion Enhancer 1 (MIEN1) in Cancer Progression and Metastasis. Front Oncol 2019; 9:868. [PMID: 31552186 PMCID: PMC6738349 DOI: 10.3389/fonc.2019.00868] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 08/21/2019] [Indexed: 02/05/2023] Open
Abstract
Tumor metastasis is a sequential event accounting for numerous cancer-related fatalities worldwide. The process of metastasis serially involves invasion, intravasation, extravasation, and tumor growth at the secondary site. Migration and invasion enhancer 1 (MIEN1) is a membrane associated protein overexpressed in various human cancers. Biological activity of MIEN1 is driven by geranylgeranyltransferase-I mediated prenylation at CAAX motif and methylation of the prenylated protein that anchors MIEN1 into the cellular membrane. Post-translationally modified MIEN1 interacts with Syk kinase and Annexin A2 protein; polymerizes G-actin and stabilizes F-actin filament; induces focal adhesion kinase phosphorylation and decrease cofilin phosphorylation implicated in both invasion and metastasis of different cancer types. In the present review, we discuss the structure, function, and involvement of MIEN1 in cancer progression. We also highlight the future prospects of MIEN1 as an emerging molecule and novel target in cancer cell invasion and metastasis.
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Affiliation(s)
- Prem Prakash Kushwaha
- Department of Biochemistry, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, India
| | - Sanjay Gupta
- Department of Urology, Case Western Reserve University, Cleveland, OH, United States.,The Urology Institute, University Hospitals Cleveland Medical Center, Cleveland, OH, United States.,Department of Nutrition, Case Western Reserve University, Cleveland, OH, United States.,Divison of General Medical Sciences, Case Comprehensive Cancer Center, Cleveland, OH, United States.,Department of Urology, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, United States
| | - Atul Kumar Singh
- Department of Biochemistry, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, India
| | - Shashank Kumar
- Department of Biochemistry, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, India
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7
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Rozenberg JM, Taylor JM, Mack CP. RBPJ binds to consensus and methylated cis elements within phased nucleosomes and controls gene expression in human aortic smooth muscle cells in cooperation with SRF. Nucleic Acids Res 2019; 46:8232-8244. [PMID: 29931229 PMCID: PMC6144787 DOI: 10.1093/nar/gky562] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 06/07/2018] [Indexed: 11/15/2022] Open
Abstract
Given our previous demonstration that RBPJ binds a methylated repressor element and regulates smooth muscle cell (SMC)-specific gene expression, we used genome-wide approaches to identify RBPJ binding regions in human aortic SMC and to assess RBPJ's effects on chromatin structure and gene expression. RBPJ bound to consensus cis elements, but also to TCmGGGA sequences within Alu repeats that were less transcriptionally active as assessed by DNAse hypersensitivity, H3K9 acetylation, and Notch3 and RNA Pol II binding. Interestingly, RBPJ binding was frequently detected at the borders of open chromatin, and a large fraction of genes induced or repressed by RBPJ depletion were associated with this cluster of RBPJ binding sites. RBPJ binding dramatically co-localized with serum response factor (SRF) and RNA seq experiments in RBPJ- and SRF-depleted SMC demonstrated that these factors interact functionally to regulate the contraction and inflammatory gene programs that help define SMC phenotype. Finally, we showed that RBPJ bound preferentially to phased nucleosomes independent of active chromatin marks and to cis elements positioned at the beginning and middle of the nucleosome dyad. These novel findings add important insight into RBPJ's role in chromatin structure and gene expression in SMC.
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Affiliation(s)
- Julian M Rozenberg
- Department of Pathology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Joan M Taylor
- Department of Pathology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Christopher P Mack
- Department of Pathology, University of North Carolina, Chapel Hill, NC 27599, USA
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8
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Jin L, Qin G, Zhao C, Yu X, Lu J, Meng H. The deamination mechanism of the 5,6-dihydro-6-hydro-6-hydroxylcytosine and 5,6-dihydro-5-methyl-6-hydroxylcytosine under typical bisulfite conditions. Mol Phys 2019. [DOI: 10.1080/00268976.2018.1541105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Lingxia Jin
- Shaanxi Key Laboratory of Catalysis, School of Chemical & Environment Science, Shaanxi University of Technology, Hanzhong, People’s Republic of China
| | - Gongwei Qin
- Bioresources Key Laboratory of Shaanxi Province, College of Biological Science and Technology, Shaanxi University of Technology, Hanzhong, People’s Republic of China
| | - Caibin Zhao
- Shaanxi Key Laboratory of Catalysis, School of Chemical & Environment Science, Shaanxi University of Technology, Hanzhong, People’s Republic of China
| | - Xiaohu Yu
- Shaanxi Key Laboratory of Catalysis, School of Chemical & Environment Science, Shaanxi University of Technology, Hanzhong, People’s Republic of China
| | - Jiufu Lu
- Shaanxi Key Laboratory of Catalysis, School of Chemical & Environment Science, Shaanxi University of Technology, Hanzhong, People’s Republic of China
| | - Hao Meng
- College of Physics and Telecom Engineering, Shaanxi University of Technology, Hanzhong, People’s Republic of China
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9
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MIEN1 is tightly regulated by SINE Alu methylation in its promoter. Oncotarget 2018; 7:65307-65319. [PMID: 27589566 PMCID: PMC5323157 DOI: 10.18632/oncotarget.11675] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 08/18/2016] [Indexed: 01/26/2023] Open
Abstract
Migration and invasion enhancer 1 (MIEN1) is a novel gene involved in prostate cancer progression by enhancing prostate cancer cell migration and invasion. DNA methylation, an important epigenetic regulation, is one of the most widely altered mechanisms in prostate cancer. This phenomenon frames the basis to study the DNA methylation patterns in the promoter region of MIEN1. Bisulfite pyrosequencing demonstrates the MIEN1 promoter contains a short interspersed nuclear Alu element (SINE Alu) repeat sequence. Validation of methylation inhibition on MIEN1 was performed using nucleoside analogs and non-nucleoside inhibitors and resulted in an increase in both MIEN1 RNA and protein in normal cells. MIEN1 mRNA and protein increases upon inhibition of individual DNA methyltransferases using RNA interference technologies. Furthermore, dual luciferase reporter assays, in silico analysis, and chromatin immunoprecipitation assays identified a sequence upstream of the transcription start site that has a site for binding of the USF transcription factors. These results suggest the MIEN1 promoter has a SINE Alu region that is hypermethylated in normal cells leading to repression of the gene. In cancer, the hypomethylation of a part of this repeat, in addition to the binding of USF, results in MIEN1 expression.
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10
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Court F, Arnaud P. An annotated list of bivalent chromatin regions in human ES cells: a new tool for cancer epigenetic research. Oncotarget 2018; 8:4110-4124. [PMID: 27926531 PMCID: PMC5354816 DOI: 10.18632/oncotarget.13746] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 11/23/2016] [Indexed: 12/12/2022] Open
Abstract
CpG islands (CGI) marked by bivalent chromatin in stem cells are believed to be more prone to aberrant DNA methylation in tumor cells. The robustness and genome-wide extent of this instructive program in different cancer types remain to be determined. To address this issue we developed a user-friendly approach to integrate the stem cell chromatin signature in customized DNA methylation analyses. We used publicly available ChIP-sequencing datasets of several human embryonic stem cell (hESC) lines to determine the extent of bivalent chromatin genome-wide. We then created annotated lists of high-confidence bivalent, H3K4me3-only and H3K27me3-only chromatin regions. The main features of bivalent regions included localization in CGI/promoters, depletion in retroelements and enrichment in specific histone modifications, including the poorly characterized H3K23me2 mark. Moreover, bivalent promoters could be classified in three clusters based on PRC2 and PolII complexes occupancy. Genes with bivalent promoters of the PRC2-defined cluster displayed the lowest expression upon differentiation. As proof-of-concept, we assessed the DNA methylation pattern of eight types of tumors and confirmed that aberrant cancer-associated DNA hypermethylation preferentially targets CGI characterized by bivalent chromatin in hESCs. We also found that such aberrant DNA hypermethylation affected particularly bivalent CGI/promoters associated with genes that tend to remain repressed upon differentiation. Strikingly, bivalent CGI were the most affected by aberrant DNA hypermethylation in both CpG Island Methylator Phenotype-positive (CIMP+) and CIMP-negative tumors, suggesting that, besides transcriptional silencing in the pre-tumorigenic cells, the bivalent chromatin signature in hESCs is a key determinant of the instructive program for aberrant DNA methylation.
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Affiliation(s)
- Franck Court
- CNRS-UMR 6293, Clermont-Ferrand, 63001, France.,INSERM-U1103, Clermont-Ferrand, 63001, France.,Université Clermont Auvergne, GReD Laboratory, Clermont-Ferrand, 63000, France
| | - Philippe Arnaud
- CNRS-UMR 6293, Clermont-Ferrand, 63001, France.,INSERM-U1103, Clermont-Ferrand, 63001, France.,Université Clermont Auvergne, GReD Laboratory, Clermont-Ferrand, 63000, France
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11
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Abstract
The field of genomic biomarkers in melanoma has evolved dramatically in the past few decades. Whereas much of the prior focus was on molecular assessment of tumor tissue, circulating tumor cells (CTCs), and cell-free circulating tumor DNA (ctDNA) as sources of a "liquid biopsy" in cancer patients provide promising potential as a method to assess tumor progression, identify targets for therapy, and evaluate clinical response to treatment. Blood biomarker assays have the advantage of being noninvasive, allow for dynamic evaluation of disease over a serial time frame, and help to address the issue of tissue sampling bias and tumor heterogeneity. However, there remains an assortment of technologies and techniques to isolate and detect CTCs and ctDNA and a standardized method has yet to be established. Despite these challenges, multiple studies have already demonstrated the clinical prognostic utility of blood-based genomic biomarker assays. With the advent of next-generation sequencing and genome-wide ctDNA analysis, this will undoubtedly lead to an improved understanding of tumor progression, help to identify new targets for treatment, and improve monitoring of treatment response and development of resistance.
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Affiliation(s)
- Kelly Huynh
- Department of Surgical Oncology, John Wayne Cancer Institute at Providence Saint John's Health Center, Santa Monica, CA 90404
| | - Dave S B Hoon
- Department of Molecular Oncology John Wayne Cancer Institute at Providence Saint John's Health Center Santa Monica, California
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12
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Huber C, von Watzdorf J, Marx A. 5-methylcytosine-sensitive variants of Thermococcus kodakaraensis DNA polymerase. Nucleic Acids Res 2016; 44:9881-9890. [PMID: 27651460 PMCID: PMC5175357 DOI: 10.1093/nar/gkw812] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 09/03/2016] [Accepted: 09/05/2016] [Indexed: 12/28/2022] Open
Abstract
DNA methylation of cytosine in eukaryotic cells is a common epigenetic modification, which plays an important role in gene expression and thus affects various cellular processes like development and carcinogenesis. The occurrence of 5-methyl-2'-deoxycytosine (5mC) as well as the distribution pattern of this epigenetic marker were shown to be crucial for gene regulation and can serve as important biomarkers for diagnostics. DNA polymerases distinguish little, if any, between incorporation opposite C and 5mC, which is not surprising since the site of methylation is not involved in Watson-Crick recognition. Here, we describe the development of a DNA polymerase variant that incorporates the canonical 2'-deoxyguanosine 5'-monophosphate (dGMP) opposite C with higher efficiency compared to 5mC. The variant of Thermococcus kodakaraensis (KOD) exo- DNA polymerase was discovered by screening mutant libraries that were built by rational design. We discovered that an amino acid substitution at a single site that does not directly interact with the templating nucleobase, may alter the ability of the DNA polymerase in processing C in comparison to 5mC. Employing these findings in combination with a nucleotide, which is fluorescently labeled at the terminal phosphate, indicates the potential use of the mutant DNA polymerase in the detection of 5mC.
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Affiliation(s)
- Claudia Huber
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstraße 10, D-78457 Konstanz, Germany
| | - Janina von Watzdorf
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstraße 10, D-78457 Konstanz, Germany
| | - Andreas Marx
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstraße 10, D-78457 Konstanz, Germany
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13
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von Watzdorf J, Marx A. 6-Substituted 2-Aminopurine-2'-deoxyribonucleoside 5'-Triphosphates that Trace Cytosine Methylation. Chembiochem 2016; 17:1532-40. [PMID: 27253512 PMCID: PMC5095873 DOI: 10.1002/cbic.201600245] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Indexed: 12/26/2022]
Abstract
Gene expression is extensively regulated by the occurrence and distribution of the epigenetic marker 2′‐deoxy 5‐methylcytosine (5mC) in genomic DNA. Because of its effects on tumorigenesis there is an important link to human health. In addition, detection of 5mC can serve as an outstanding biomarker for diagnostics as well as for disease therapy. Our previous studies have already shown that, by processing O6‐alkylated 2′‐deoxyguanosine triphosphate (dGTP) analogues, DNA polymerases are able to sense the presence of a single 5mC unit in a template. Here we present the synthesis and evaluation of an extended toolbox of 6‐substituted 2‐aminopurine‐2′‐deoxyribonucleoside 5′‐triphosphates modified at position 6 with various functionalities. We found that sensing of 5‐methylation by this class of nucleotides is more general, not being restricted to O6‐alkyl modification of dGTP but also applying to other functionalities.
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Affiliation(s)
- Janina von Watzdorf
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany
| | - Andreas Marx
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany.
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Vaidya H, Rumph C, Katula KS. Inactivation of the WNT5A Alternative Promoter B Is Associated with DNA Methylation and Histone Modification in Osteosarcoma Cell Lines U2OS and SaOS-2. PLoS One 2016; 11:e0151392. [PMID: 26978652 PMCID: PMC4792504 DOI: 10.1371/journal.pone.0151392] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Accepted: 02/26/2016] [Indexed: 01/01/2023] Open
Abstract
WNT5A is a secreted ligand involved in Wnt pathway signaling and has a role in cell movement and differentiation. Altered WNT5A expression is associated with various cancers, although in most studies the focus has been on only one of the known WNT5A isoforms. In this study, we analyzed expression from two of the major WNT5A promoters, termed promoter A and promoter B, in normal human osteoblasts, SaOS-2 and U2OS osteosarcoma cell lines, and osteosarcoma tumor tissue. We found that both promoters A and B are active in normal osteoblasts with nearly 11-fold more promoter B than A transcripts. Promoter B but not promoter A transcripts are decreased or nearly undetectable in the SaOS-2 and U2OS cell lines and osteosarcoma tumor tissues. Transient transfection of promoter A and promoter B reporter constructs confirmed that SaOS-2 cells have the necessary factors to transcribe both promoters. Bisulfite sequencing analysis revealed that three CpG enriched regions upstream of the promoter B exon 1βare highly methylated in both SaOS-2 and U2OS cells. The CpG island sub-region R6 located in promoter B exon 1β was approximately 51% methylated in SaOS-2 and 25% methylated in U2OS. Region 3 was approximately 28% methylated in normal osteoblasts, whereas the others were unmethylated. Promoter B was re-activated by treatment of SaOS-2 cells with 1 μM 5-azacytidine, which was associated with only a small insignificant change in methylation of sub-region R6. ChIP analysis of U2OS and SaOS-2 cells indicated that the promoter B region is less enriched in the active histone mark H3K4me3, in comparison to promoter A and that there is increased enrichment of the repressive mark H3K27me3 in association with the promoter B genomic region in the cell line SaOS-2. These findings show that epigenetic inactivation of the WNT5A promoter B involves both DNA methylation and histone modifications and suggest that differential expression of the WNT5A alternative promoters A and B is a characteristic of osteosarcomas.
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Affiliation(s)
- Himani Vaidya
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Candie Rumph
- Department of Biology, The University of North Carolina Greensboro, Greensboro, North Carolina, United States of America
| | - Karen S. Katula
- Department of Biology, The University of North Carolina Greensboro, Greensboro, North Carolina, United States of America
- * E-mail:
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15
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von Watzdorf J, Leitner K, Marx A. Modified Nucleotides for Discrimination between Cytosine and the Epigenetic Marker 5-Methylcytosine. Angew Chem Int Ed Engl 2016; 55:3229-32. [PMID: 26835661 PMCID: PMC4949677 DOI: 10.1002/anie.201511520] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Indexed: 12/31/2022]
Abstract
5‐Methyl‐2′‐deoxycytosine, the most common epigenetic marker of DNA in eukaryotic cells, plays a key role in gene regulation and affects various cellular processes such as development and carcinogenesis. Therefore, the detection of 5mC can serve as an important biomarker for diagnostics. Here we describe that modified dGTP analogues as well as modified primers are able to sense the presence or absence of a single methylation of C, even though this modification does not interfere directly with Watson–Crick nucleobase pairing. By screening several modified nucleotide scaffolds, O6‐modified 2′‐deoxyguanosine analogues were identified as discriminating between C and 5mC. These modified nucleotides might find application in site‐specific 5mC detection, for example, through real‐time PCR approaches.
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Affiliation(s)
- Janina von Watzdorf
- Fachbereich Chemie, Graduiertenschule Chemische, Biologie Konstanz, Universität Konstanz, Universitätsstrasse 10, 78457, Konstanz, Deutschland
| | - Kim Leitner
- Fachbereich Chemie, Graduiertenschule Chemische, Biologie Konstanz, Universität Konstanz, Universitätsstrasse 10, 78457, Konstanz, Deutschland
| | - Andreas Marx
- Fachbereich Chemie, Graduiertenschule Chemische, Biologie Konstanz, Universität Konstanz, Universitätsstrasse 10, 78457, Konstanz, Deutschland.
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16
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von Watzdorf J, Leitner K, Marx A. Modifizierte Nukleotide für die Diskriminierung zwischen Cytosin und dem epigenetischen Marker 5-Methylcytosin. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201511520] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Janina von Watzdorf
- Fachbereich Chemie, Graduiertenschule Chemische Biologie Konstanz; Universität Konstanz; Universitätsstraße 10 78457 Konstanz Deutschland
| | - Kim Leitner
- Fachbereich Chemie, Graduiertenschule Chemische Biologie Konstanz; Universität Konstanz; Universitätsstraße 10 78457 Konstanz Deutschland
| | - Andreas Marx
- Fachbereich Chemie, Graduiertenschule Chemische Biologie Konstanz; Universität Konstanz; Universitätsstraße 10 78457 Konstanz Deutschland
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17
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Grandi FC, Rosser JM, Newkirk SJ, Yin J, Jiang X, Xing Z, Whitmore L, Bashir S, Ivics Z, Izsvák Z, Ye P, Yu YE, An W. Retrotransposition creates sloping shores: a graded influence of hypomethylated CpG islands on flanking CpG sites. Genome Res 2015; 25:1135-46. [PMID: 25995269 PMCID: PMC4509998 DOI: 10.1101/gr.185132.114] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 05/19/2015] [Indexed: 11/25/2022]
Abstract
Long interspersed elements (LINEs), through both self-mobilization and trans-mobilization of short interspersed elements and processed pseudogenes, have made an indelible impact on the structure and function of the human genome. One consequence is the creation of new CpG islands (CGIs). In fact, more than half of all CGIs in the genome are associated with repetitive DNA, three-quarters of which are derived from retrotransposons. However, little is known about the epigenetic impact of newly inserted CGIs. We utilized a transgenic LINE-1 mouse model and tracked DNA methylation dynamics of individual germline insertions during mouse development. The retrotransposed GFP marker sequence, a strong CGI, is hypomethylated in male germ cells but hypermethylated in somatic tissues, regardless of genomic location. The GFP marker is similarly methylated when delivered into the genome via the Sleeping Beauty DNA transposon, suggesting that the observed methylation pattern may be independent of the mode of insertion. Comparative analyses between insertion- and non-insertion-containing alleles further reveal a graded influence of the retrotransposed CGI on flanking CpG sites, a phenomenon that we described as "sloping shores." Computational analyses of human and mouse methylomic data at single-base resolution confirm that sloping shores are universal for hypomethylated CGIs in sperm and somatic tissues. Additionally, the slope of a hypomethylated CGI can be affected by closely positioned CGI neighbors. Finally, by tracing sloping shore dynamics through embryonic and germ cell reprogramming, we found evidence of bookmarking, a mechanism that likely determines which CGIs will be eventually hyper- or hypomethylated.
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Affiliation(s)
- Fiorella C Grandi
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA
| | - James M Rosser
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA
| | - Simon J Newkirk
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA; Department of Pharmaceutical Sciences, South Dakota State University, Brookings, South Dakota 57007, USA
| | - Jun Yin
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA
| | - Xiaoling Jiang
- The Children's Guild Foundation Down Syndrome Research Program, Department of Cancer Genetics and Genetics Program, Roswell Park Cancer Institute, Buffalo, New York 14263, USA
| | - Zhuo Xing
- The Children's Guild Foundation Down Syndrome Research Program, Department of Cancer Genetics and Genetics Program, Roswell Park Cancer Institute, Buffalo, New York 14263, USA
| | - Leanne Whitmore
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA
| | - Sanum Bashir
- Max Delbrück Center for Molecular Medicine, 13092 Berlin, Germany
| | - Zoltán Ivics
- Division of Medical Biotechnology, Paul Ehrlich Institute, 63225 Langen, Germany
| | - Zsuzsanna Izsvák
- Max Delbrück Center for Molecular Medicine, 13092 Berlin, Germany
| | - Ping Ye
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA
| | - Y Eugene Yu
- The Children's Guild Foundation Down Syndrome Research Program, Department of Cancer Genetics and Genetics Program, Roswell Park Cancer Institute, Buffalo, New York 14263, USA
| | - Wenfeng An
- Department of Pharmaceutical Sciences, South Dakota State University, Brookings, South Dakota 57007, USA
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Chandrashekar DS, Dey P, Acharya KK. GREAM: A Web Server to Short-List Potentially Important Genomic Repeat Elements Based on Over-/Under-Representation in Specific Chromosomal Locations, Such as the Gene Neighborhoods, within or across 17 Mammalian Species. PLoS One 2015. [PMID: 26208093 PMCID: PMC4514817 DOI: 10.1371/journal.pone.0133647] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Background Genome-wide repeat sequences, such as LINEs, SINEs and LTRs share a considerable part of the mammalian nuclear genomes. These repeat elements seem to be important for multiple functions including the regulation of transcription initiation, alternative splicing and DNA methylation. But it is not possible to study all repeats and, hence, it would help to short-list before exploring their potential functional significance via experimental studies and/or detailed in silico analyses. Result We developed the ‘Genomic Repeat Element Analyzer for Mammals’ (GREAM) for analysis, screening and selection of potentially important mammalian genomic repeats. This web-server offers many novel utilities. For example, this is the only tool that can reveal a categorized list of specific types of transposons, retro-transposons and other genome-wide repetitive elements that are statistically over-/under-represented in regions around a set of genes, such as those expressed differentially in a disease condition. The output displays the position and frequency of identified elements within the specified regions. In addition, GREAM offers two other types of analyses of genomic repeat sequences: a) enrichment within chromosomal region(s) of interest, and b) comparative distribution across the neighborhood of orthologous genes. GREAM successfully short-listed a repeat element (MER20) known to contain functional motifs. In other case studies, we could use GREAM to short-list repetitive elements in the azoospermia factor a (AZFa) region of the human Y chromosome and those around the genes associated with rat liver injury. GREAM could also identify five over-represented repeats around some of the human and mouse transcription factor coding genes that had conserved expression patterns across the two species. Conclusion GREAM has been developed to provide an impetus to research on the role of repetitive sequences in mammalian genomes by offering easy selection of more interesting repeats in various contexts/regions. GREAM is freely available at http://resource.ibab.ac.in/GREAM/.
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Affiliation(s)
- Darshan Shimoga Chandrashekar
- Institute of Bioinformatics and Applied Biotechnology (IBAB), Biotech Park, Electronic City, Bengaluru (Bangalore), 560100, Karnataka state, India
- Manipal University, Manipal, 576104, Karnataka state, India
| | - Poulami Dey
- Institute of Bioinformatics and Applied Biotechnology (IBAB), Biotech Park, Electronic City, Bengaluru (Bangalore), 560100, Karnataka state, India
- Manipal University, Manipal, 576104, Karnataka state, India
| | - Kshitish K. Acharya
- Institute of Bioinformatics and Applied Biotechnology (IBAB), Biotech Park, Electronic City, Bengaluru (Bangalore), 560100, Karnataka state, India
- Shodhaka Life Sciences Pvt. Ltd., IBAB, Biotech Park, Bengaluru (Bangalore), 560100, Karnataka state, India
- * E-mail:
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19
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Chromatin methylation and cardiovascular aging. J Mol Cell Cardiol 2015; 83:21-31. [DOI: 10.1016/j.yjmcc.2015.02.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 01/20/2015] [Accepted: 02/12/2015] [Indexed: 12/26/2022]
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20
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Pon JR, Marra MA. Driver and Passenger Mutations in Cancer. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2015; 10:25-50. [DOI: 10.1146/annurev-pathol-012414-040312] [Citation(s) in RCA: 216] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Julia R. Pon
- Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, Canada V5Z 1L3;
| | - Marco A. Marra
- Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, Canada V5Z 1L3;
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada V6T 1Z4;
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21
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Dantas Machado AC, Zhou T, Rao S, Goel P, Rastogi C, Lazarovici A, Bussemaker HJ, Rohs R. Evolving insights on how cytosine methylation affects protein-DNA binding. Brief Funct Genomics 2015; 14:61-73. [PMID: 25319759 PMCID: PMC4303714 DOI: 10.1093/bfgp/elu040] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Many anecdotal observations exist of a regulatory effect of DNA methylation on gene expression. However, in general, the underlying mechanisms of this effect are poorly understood. In this review, we summarize what is currently known about how this important, but mysterious, epigenetic mark impacts cellular functions. Cytosine methylation can abrogate or enhance interactions with DNA-binding proteins, or it may have no effect, depending on the context. Despite being only a small chemical change, the addition of a methyl group to cytosine can affect base readout via hydrophobic contacts in the major groove and shape readout via electrostatic contacts in the minor groove. We discuss the recent discovery that CpG methylation increases DNase I cleavage at adjacent positions by an order of magnitude through altering the local 3D DNA shape and the possible implications of this structural insight for understanding the methylation sensitivity of transcription factors (TFs). Additionally, 5-methylcytosines change the stability of nucleosomes and, thus, affect the local chromatin structure and access of TFs to genomic DNA. Given these complexities, it seems unlikely that the influence of DNA methylation on protein-DNA binding can be captured in a small set of general rules. Hence, data-driven approaches may be essential to gain a better understanding of these mechanisms.
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22
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Chatterjee R, He X, Huang D, FitzGerald P, Smith A, Vinson C. High-resolution genome-wide DNA methylation maps of mouse primary female dermal fibroblasts and keratinocytes. Epigenetics Chromatin 2014; 7:35. [PMID: 25699092 PMCID: PMC4333159 DOI: 10.1186/1756-8935-7-35] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 11/04/2014] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Genome-wide DNA methylation at a single nucleotide resolution in different primary cells of the mammalian genome helps to determine the characteristics and functions of tissue-specific hypomethylated regions (TS-HMRs). We determined genome-wide cytosine methylation maps at 91X and 36X coverage of newborn female mouse primary dermal fibroblasts and keratinocytes and compared with mRNA-seq gene expression data. RESULTS These high coverage methylation maps were used to identify HMRs in both cell types. A total of 2.91% of the genome are in keratinocyte HMRs, and 2.15% of the genome are in fibroblast HMRs with 1.75% being common. Half of the TS-HMRs are extensions of common HMRs, and the remaining are unique TS-HMRs. Four levels of CG methylation are observed: 1) total unmethylation for CG dinucleotides in HMRs in CGIs that are active in all tissues; 2) 10% to 40% methylation for TS-HMRs; 3) 60% methylation for TS-HMRs in cells types where they are not in HMRs; and 4) 70% methylation for the nonfunctioning part of the genome. SINE elements are depleted inside the TS-HMRs, while highly enriched in the surrounding regions. Hypomethylation at the last exon shows gene repression, while demethylation toward the gene body positively correlates with gene expression. The overlapping HMRs have a more complex relationship with gene expression. The common HMRs and TS-HMRs are each enriched for distinct Transcription Factor Binding Sites (TFBS). C/EBPβ binds to methylated regions outside of HMRs while CTCF prefers to bind in HMRs, highlighting these two parts of the genome and their potential interactions. CONCLUSIONS Keratinocytes and fibroblasts are of epithelial and mesenchymal origin. High-resolution methylation maps in these two cell types can be used as reference methylomes for analyzing epigenetic mechanisms in several diseases including cancer. Please see related article at the following link: http://www.epigeneticsandchromatin.com/content/7/1/34.
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Affiliation(s)
- Raghunath Chatterjee
- />Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Bethesda, MD 20892 USA
- />Human Genetics Unit, Indian Statistical Institute, 203 B. T. Road, Kolkata, 700108 India
| | - Ximiao He
- />Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Bethesda, MD 20892 USA
| | - Di Huang
- />NCBI, National Institutes of Health, 8600 Rockville Pike, Bethesda, MD 20894 USA
| | - Peter FitzGerald
- />Genome Analysis Unit, Genetics Branch, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Bethesda, MD 20892 USA
| | - Andrew Smith
- />Molecular and Computational Biology, University of Southern California, 1050 Childs Way, Los Angeles, CA 90089 USA
| | - Charles Vinson
- />Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Bethesda, MD 20892 USA
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Miceli M, Bontempo P, Nebbioso A, Altucci L. Natural compounds in epigenetics: a current view. Food Chem Toxicol 2014; 73:71-83. [PMID: 25139119 DOI: 10.1016/j.fct.2014.08.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 08/06/2014] [Accepted: 08/08/2014] [Indexed: 01/03/2023]
Abstract
The successful treatment of many human diseases, including cancer, has come to be considered a major challenge, as patient response to therapy is difficult to predict. Recently, considerable efforts are being focused on the development of new tools to meet the growing demand for personalized medicine. With few exceptions, synthetic compounds have been unable to meet initial expectations for their clinical use. The last twenty years have been characterized by the failure of several drugs in advanced clinical development, possibly due to the insufficient understanding of molecular pathways underlying their mechanism of action. Although the biodiversity of compounds found in nature has been poorly explored until now, the field of naturally occurring drugs is rapidly expanding. Here, we review the current knowledge on the use of natural compounds with particular emphasis on those that display a chromatin remodeling effect coupled with anticancer action.
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Affiliation(s)
- Marco Miceli
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Seconda Universita' di Napoli, Via L. De Crecchio 7, 80138 Napoli, Italy; Istituto di Genetica e Biofisica, Adriano Buzzati-Traverso, IGB, Via P. Castellino 111, 80131 Napoli, Italy
| | - Paola Bontempo
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Seconda Universita' di Napoli, Via L. De Crecchio 7, 80138 Napoli, Italy
| | - Angela Nebbioso
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Seconda Universita' di Napoli, Via L. De Crecchio 7, 80138 Napoli, Italy
| | - Lucia Altucci
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Seconda Universita' di Napoli, Via L. De Crecchio 7, 80138 Napoli, Italy; Istituto di Genetica e Biofisica, Adriano Buzzati-Traverso, IGB, Via P. Castellino 111, 80131 Napoli, Italy.
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24
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Syed AS, Korsching SI. Positive Darwinian selection in the singularly large taste receptor gene family of an 'ancient' fish, Latimeria chalumnae. BMC Genomics 2014; 15:650. [PMID: 25091523 PMCID: PMC4132921 DOI: 10.1186/1471-2164-15-650] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 07/29/2014] [Indexed: 11/11/2022] Open
Abstract
Background Chemical senses are one of the foremost means by which organisms make sense of their environment, among them the olfactory and gustatory sense of vertebrates and arthropods. Both senses use large repertoires of receptors to achieve perception of complex chemosensory stimuli. High evolutionary dynamics of some olfactory and gustatory receptor gene families result in considerable variance of chemosensory perception between species. Interestingly, both ora/v1r genes and the closely related t2r genes constitute small and rather conserved families in teleost fish, but show rapid evolution and large species differences in tetrapods. To understand this transition, chemosensory gene repertoires of earlier diverging members of the tetrapod lineage, i.e. lobe-finned fish such as Latimeria would be of high interest. Results We report here the complete T2R repertoire of Latimeria chalumnae, using thorough data mining and extensive phylogenetic analysis. Eighty t2r genes were identified, by far the largest family reported for any species so far. The genomic neighborhood of t2r genes is enriched in repeat elements, which may have facilitated the extensive gene duplication events resulting in such a large family. Examination of non-synonymous vs. synonymous substitution rates (dN/dS) suggests pronounced positive Darwinian selection in Latimeria T2Rs, conceivably ensuring efficient neo-functionalization of newly born t2r genes. Notably, both traits, positive selection and enrichment of repeat elements in the genomic neighborhood, are absent in the twenty v1r genes of Latimeria. Sequence divergence in Latimeria T2Rs and V1Rs is high, reminescent of the corresponding teleost families. Some conserved sequence motifs of Latimeria T2Rs and V1Rs are shared with the respective teleost but not tetrapod genes, consistent with a potential role of such motifs in detection of aquatic chemosensory stimuli. Conclusions The singularly large T2R repertoire of Latimeria may have been generated by facilitating local gene duplication via increased density of repeat elements, and efficient neofunctionalization via positive Darwinian selection. The high evolutionary dynamics of tetrapod t2r gene families precedes the emergence of tetrapods, i.e. the water-to-land transition, and thus constitutes a basal feature of the lobe-finned lineage of vertebrates. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-650) contains supplementary material, which is available to authorized users.
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Aschenbrenner J, Drum M, Topal H, Wieland M, Marx A. Direct sensing of 5-methylcytosine by polymerase chain reaction. Angew Chem Int Ed Engl 2014; 53:8154-8. [PMID: 24923910 PMCID: PMC4499253 DOI: 10.1002/anie.201403745] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Indexed: 12/22/2022]
Abstract
The epigenetic control of genes by the methylation of cytosine resulting in 5-methylcytosine (5mC) has fundamental implications for human development and disease. Analysis of alterations in DNA methylation patterns is an emerging tool for cancer diagnostics and prognostics. Here we report that two thermostable DNA polymerases, namely the DNA polymerase KlenTaq derived from Thermus aquaticus and the KOD DNA polymerase from Thermococcus kodakaraensis, are able to extend 3'-mismatched primer strands more efficiently from 5 mC than from unmethylated C. This feature was advanced by generating a DNA polymerase mutant with further improved 5mC/C discrimination properties and its successful application in a novel methylation-specific PCR approach directly from untreated human genomic DNA.
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Affiliation(s)
- Joos Aschenbrenner
- Department of Chemistry, Konstanz Research School Chemical Biology, University of KonstanzUniversitätsstrasse 10, 78457 Konstanz (Germany)
| | - Matthias Drum
- Department of Chemistry, Konstanz Research School Chemical Biology, University of KonstanzUniversitätsstrasse 10, 78457 Konstanz (Germany)
| | - Hüsnü Topal
- Department of Chemistry, Konstanz Research School Chemical Biology, University of KonstanzUniversitätsstrasse 10, 78457 Konstanz (Germany)
| | - Markus Wieland
- Department of Chemistry, Konstanz Research School Chemical Biology, University of KonstanzUniversitätsstrasse 10, 78457 Konstanz (Germany)
| | - Andreas Marx
- Department of Chemistry, Konstanz Research School Chemical Biology, University of KonstanzUniversitätsstrasse 10, 78457 Konstanz (Germany)
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Zhi H, Ning S, Li X, Li Y, Wu W, Li X. A novel reannotation strategy for dissecting DNA methylation patterns of human long intergenic non-coding RNAs in cancers. Nucleic Acids Res 2014; 42:8258-70. [PMID: 25013169 PMCID: PMC4117791 DOI: 10.1093/nar/gku575] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Despite growing consensus that long intergenic non-coding ribonucleic acids (lincRNAs) are modulators of cancer, the knowledge about the deoxyribonucleic acid (DNA) methylation patterns of lincRNAs in cancers remains limited. In this study, we constructed DNA methylation profiles for 4629 tumors and 705 normal tissue samples from 20 different types of human cancer by reannotating data of DNA methylation arrays. We found that lincRNAs had different promoter methylation patterns in cancers. We classified 2461 lincRNAs into two categories and three subcategories, according to their promoter methylation patterns in tumors. LincRNAs with resistant methylation patterns in tumors had conserved transcriptional regulation regions and were ubiquitously expressed across normal tissues. By integrating cancer subtype data and patient clinical information, we identified lincRNAs with promoter methylation patterns that were associated with cancer status, subtype or prognosis for several cancers. Network analysis of aberrantly methylated lincRNAs in cancers showed that lincRNAs with aberrant methylation patterns might be involved in cancer development and progression. The methylated and demethylated lincRNAs identified in this study provide novel insights for developing cancer biomarkers and potential therapeutic targets.
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Affiliation(s)
- Hui Zhi
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin 150081, China
| | - Shangwei Ning
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin 150081, China
| | - Xiang Li
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin 150081, China
| | - Yuyun Li
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin 150081, China
| | - Wei Wu
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin 150081, China
| | - Xia Li
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin 150081, China
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Aschenbrenner J, Drum M, Topal H, Wieland M, Marx A. Detektion von 5-Methylcytosin in unbehandelter genomischer DNA durch Polymerasekettenreaktion. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201403745] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Cesaroni M, Powell J, Sapienza C. Validation of methylation biomarkers that distinguish normal colon mucosa of cancer patients from normal colon mucosa of patients without cancer. Cancer Prev Res (Phila) 2014; 7:717-26. [PMID: 24806665 DOI: 10.1158/1940-6207.capr-13-0407] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We have validated differences in DNA methylation levels of candidate genes previously reported to discriminate between normal colon mucosa of patients with colon cancer and normal colon mucosa of individuals without cancer. Here, we report that CpG sites in 16 of the 30 candidate genes selected show significant differences in mean methylation level in normal colon mucosa of 24 patients with cancer and 24 controls. A support vector machine trained on these data and data for an additional 66 CpGs yielded an 18-gene signature, composed of ten of the validated candidate genes plus eight additional candidates. This model exhibited 96% sensitivity and 100% specificity in a 40-sample training set and classified all eight samples in the test set correctly. Moreover, we found a moderate-strong correlation (Pearson coefficients r = 0.253-0.722) between methylation levels in colon mucosa and methylation levels in peripheral blood for seven of the 18 genes in the support vector model. These seven genes, alone, classified 44 of the 48 patients in the validation set correctly and five CpGs selected from only two of the seven genes classified 41 of the 48 patients in the discovery set correctly. These results suggest that methylation biomarkers may be developed that will, at minimum, serve as useful objective and quantitative diagnostic complements to colonoscopy as a cancer-screening tool. These data also suggest that it may be possible to monitor biomarker methylation levels in tissues collected much less invasively than by colonoscopy.
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Affiliation(s)
- Matteo Cesaroni
- Authors' Affiliations: Fels Institute for Cancer Research and Molecular Biology; and
| | - Jasmine Powell
- Authors' Affiliations: Fels Institute for Cancer Research and Molecular Biology; and
| | - Carmen Sapienza
- Authors' Affiliations: Fels Institute for Cancer Research and Molecular Biology; and Department of Pathology and Laboratory Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania
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29
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Xue B, He L. An expanding universe of the non-coding genome in cancer biology. Carcinogenesis 2014; 35:1209-16. [PMID: 24747961 DOI: 10.1093/carcin/bgu099] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Neoplastic transformation is caused by accumulation of genetic and epigenetic alterations that ultimately convert normal cells into tumor cells with uncontrolled proliferation and survival, unlimited replicative potential and invasive growth [Hanahan,D. et al. (2011) Hallmarks of cancer: the next generation. Cell, 144, 646-674]. Although the majority of the cancer studies have focused on the functions of protein-coding genes, emerging evidence has started to reveal the importance of the vast non-coding genome, which constitutes more than 98% of the human genome. A number of non-coding RNAs (ncRNAs) derived from the 'dark matter' of the human genome exhibit cancer-specific differential expression and/or genomic alterations, and it is increasingly clear that ncRNAs, including small ncRNAs and long ncRNAs (lncRNAs), play an important role in cancer development by regulating protein-coding gene expression through diverse mechanisms. In addition to ncRNAs, nearly half of the mammalian genomes consist of transposable elements, particularly retrotransposons. Once depicted as selfish genomic parasites that propagate at the expense of host fitness, retrotransposon elements could also confer regulatory complexity to the host genomes during development and disease. Reactivation of retrotransposons in cancer, while capable of causing insertional mutagenesis and genome rearrangements to promote oncogenesis, could also alter host gene expression networks to favor tumor development. Taken together, the functional significance of non-coding genome in tumorigenesis has been previously underestimated, and diverse transcripts derived from the non-coding genome could act as integral functional components of the oncogene and tumor suppressor network.
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Affiliation(s)
- Bin Xue
- Department of Molecular and Cell Biology, Division of Cellular and Developmental Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Lin He
- Department of Molecular and Cell Biology, Division of Cellular and Developmental Biology, University of California at Berkeley, Berkeley, CA 94720, USA
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30
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Lai RK, Chen Y, Guan X, Nousome D, Sharma C, Canoll P, Bruce J, Sloan AE, Cortes E, Vonsattel JP, Su T, Delgado-Cruzata L, Gurvich I, Santella RM, Ostrom Q, Lee A, Gregersen P, Barnholtz-Sloan J. Genome-wide methylation analyses in glioblastoma multiforme. PLoS One 2014; 9:e89376. [PMID: 24586730 PMCID: PMC3931727 DOI: 10.1371/journal.pone.0089376] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 01/20/2014] [Indexed: 01/30/2023] Open
Abstract
Few studies had investigated genome-wide methylation in glioblastoma multiforme (GBM). Our goals were to study differential methylation across the genome in gene promoters using an array-based method, as well as repetitive elements using surrogate global methylation markers. The discovery sample set for this study consisted of 54 GBM from Columbia University and Case Western Reserve University, and 24 brain controls from the New York Brain Bank. We assembled a validation dataset using methylation data of 162 TCGA GBM and 140 brain controls from dbGAP. HumanMethylation27 Analysis Bead-Chips (Illumina) were used to interrogate 26,486 informative CpG sites in both the discovery and validation datasets. Global methylation levels were assessed by analysis of L1 retrotransposon (LINE1), 5 methyl-deoxycytidine (5m-dC) and 5 hydroxylmethyl-deoxycytidine (5hm-dC) in the discovery dataset. We validated a total of 1548 CpG sites (1307 genes) that were differentially methylated in GBM compared to controls. There were more than twice as many hypomethylated genes as hypermethylated ones. Both the discovery and validation datasets found 5 tumor methylation classes. Pathway analyses showed that the top ten pathways in hypomethylated genes were all related to functions of innate and acquired immunities. Among hypermethylated pathways, transcriptional regulatory network in embryonic stem cells was the most significant. In the study of global methylation markers, 5m-dC level was the best discriminant among methylation classes, whereas in survival analyses, high level of LINE1 methylation was an independent, favorable prognostic factor in the discovery dataset. Based on a pathway approach, hypermethylation in genes that control stem cell differentiation were significant, poor prognostic factors of overall survival in both the discovery and validation datasets. Approaches that targeted these methylated genes may be a future therapeutic goal.
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Affiliation(s)
- Rose K. Lai
- Departments of Neurology, Neurosurgery and Preventive Medicine, University of Southern California, Los Angeles, California, United States of America
- * E-mail:
| | - Yanwen Chen
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Xiaowei Guan
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Darryl Nousome
- Departments of Neurology, Neurosurgery and Preventive Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Charu Sharma
- Department of Radiation Oncology, Columbia University, New York, New York, United States of America
| | - Peter Canoll
- Departments of Pathology, Columbia University, New York, New York, United States of America
| | - Jeffrey Bruce
- Departments of Neurosurgery, Columbia University & Bartoli Brain Tumor Research Laboratory, Columbia University, New York, New York, United States of America
| | - Andrew E. Sloan
- Department of Neurological Surgery, University Hospitals-Case Medical Center, Case Western Reserve University, United States of America
| | - Etty Cortes
- New York Brain Bank, Columbia University, New York, New York, United States of America
| | - Jean-Paul Vonsattel
- Departments of Pathology, Columbia University, New York, New York, United States of America
- New York Brain Bank, Columbia University, New York, New York, United States of America
| | - Tao Su
- Pathology Core, Herbert Irving Cancer Center, Columbia University, New York, New York, United States of America
| | - Lissette Delgado-Cruzata
- Department of Environmental Health Sciences, Columbia University & Biomarker Core, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, New York, United States of America
| | - Irina Gurvich
- Department of Environmental Health Sciences, Columbia University & Biomarker Core, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, New York, United States of America
| | - Regina M. Santella
- Department of Environmental Health Sciences, Columbia University & Biomarker Core, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, New York, United States of America
| | - Quinn Ostrom
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Annette Lee
- Feinstein Institute of Medical Genetics, North Shore University Hospital, Manhasset, New York, United States of America
| | - Peter Gregersen
- Feinstein Institute of Medical Genetics, North Shore University Hospital, Manhasset, New York, United States of America
| | - Jill Barnholtz-Sloan
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio, United States of America
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Abstract
The myelodysplastic syndrome (MDS) is a clonal hematologic disorder that frequently evolves to acute myeloid leukemia (AML). Its pathogenesis remains unclear, but mutations in epigenetic modifiers are common and the disease often responds to DNA methylation inhibitors. We analyzed DNA methylation in the bone marrow and spleen in two mouse models of MDS/AML, the NUP98-HOXD13 (NHD13) mouse and the RUNX1 mutant mouse model. Methylation array analysis showed an average of 512/3445 (14.9%) genes hypermethylated in NHD13 MDS, and 331 (9.6%) genes hypermethylated in RUNX1 MDS. Thirty-two percent of genes in common between the two models (2/3 NHD13 mice and 2/3 RUNX1 mice) were also hypermethylated in at least two of 19 human MDS samples. Detailed analysis of 41 genes in mice showed progressive drift in DNA methylation from young to old normal bone marrow and spleen; to MDS, where we detected accelerated age-related methylation; and finally to AML, which markedly extends DNA methylation abnormalities. Most of these genes showed similar patterns in human MDS and AML. Repeat element hypomethylation was rare in MDS but marked the transition to AML in some cases. Our data show consistency in patterns of aberrant DNA methylation in human and mouse MDS and suggest that epigenetically, MDS displays an accelerated aging phenotype.
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Abstract
The term epigenetics refers to stable patterns of gene expression that are seen during differentiation or X chromosome inactivation and are not dependent on dynamic changes in coding DNA. These gene expression states are encoded in the epigenome - a collection of marks on DNA or on histone tails that are established during embryogenesis. Genome-wide studies in aging cells and tissues have uncovered stochastic DNA methylation drift (gradual increases or decreases at specific loci) that reflects imperfect maintenance of epigenetic marks. Drift creates epigenetic mosaicism in aging stem cells that could potentially restrict their plasticity and worsen phenotypes such as stem cell exhaustion and focal proliferative defects that can lead to cancer.
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Kumari V, Iyer LR, Roy R, Bhargava V, Panda S, Paul J, Verweij JJ, Clark CG, Bhattacharya A, Bhattacharya S. Genomic distribution of SINEs in Entamoeba histolytica strains: implication for genotyping. BMC Genomics 2013; 14:432. [PMID: 23815468 PMCID: PMC3716655 DOI: 10.1186/1471-2164-14-432] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 06/20/2013] [Indexed: 11/01/2022] Open
Abstract
BACKGROUND The major clinical manifestations of Entamoeba histolytica infection include amebic colitis and liver abscess. However the majority of infections remain asymptomatic. Earlier reports have shown that some E. histolytica isolates are more virulent than others, suggesting that virulence may be linked to genotype. Here we have looked at the genomic distribution of the retrotransposable short interspersed nuclear elements EhSINE1 and EhSINE2. Due to their mobile nature, some EhSINE copies may occupy different genomic locations among isolates of E. histolytica possibly affecting adjacent gene expression; this variability in location can be exploited to differentiate strains. RESULTS We have looked for EhSINE1- and EhSINE2-occupied loci in the genome sequence of Entamoeba histolytica HM-1:IMSS and searched for homologous loci in other strains to determine the insertion status of these elements. A total of 393 EhSINE1 and 119 EhSINE2 loci were analyzed in the available sequenced strains (Rahman, DS4-868, HM1:CA, KU48, KU50, KU27 and MS96-3382. Seventeen loci (13 EhSINE1 and 4 EhSINE2) were identified where a EhSINE1/EhSINE2 sequence was missing from the corresponding locus of other strains. Most of these loci were unoccupied in more than one strain. Some of the loci were analyzed experimentally for SINE occupancy using DNA from strain Rahman. These data helped to correctly assemble the nucleotide sequence at three loci in Rahman. SINE occupancy was also checked at these three loci in 7 other axenically cultivated E. histolytica strains and 16 clinical isolates. Each locus gave a single, specific amplicon with the primer sets used, making this a suitable method for strain typing. Based on presence/absence of SINE and amplification with locus-specific primers, the 23 strains could be divided into eleven genotypes. The results obtained by our method correlated with the data from other typing methods. We also report a bioinformatic analysis of EhSINE2 copies. CONCLUSIONS Our results reveal several loci with extensive polymorphism of SINE occupancy among different strains of E. histolytica and prove the principle that the genomic distribution of SINEs is a valid method for typing of E. histolytica strains.
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Affiliation(s)
- Vandana Kumari
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Lakshmi Rani Iyer
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Riti Roy
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Varsha Bhargava
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Suchita Panda
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Jaishree Paul
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Jaco J Verweij
- Laboratory for Medical Microbiology and Immunology, Laboratory for Clinical Pathology, St. Elisabeth Hospital, Tilburg, The Netherlands
| | - C Graham Clark
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Alok Bhattacharya
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Sudha Bhattacharya
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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Abstract
Cancer arises as a consequence of cumulative disruptions to cellular growth control with Darwinian selection for those heritable changes that provide the greatest clonal advantage. These traits can be acquired and stably maintained by either genetic or epigenetic means. Here, we explore the ways in which alterations in the genome and epigenome influence each other and cooperate to promote oncogenic transformation. Disruption of epigenomic control is pervasive in malignancy and can be classified as an enabling characteristic of cancer cells, akin to genome instability and mutation.
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Affiliation(s)
- Hui Shen
- USC Epigenome Center, University of Southern California, Room G511B, 1450 Biggy Street, Los Angeles, CA 90089-9061, USA
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35
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Rhyu MG, Oh JH, Hong SJ. Epigenetic implication of gene-adjacent retroelements in Helicobacter pylori-infected adults. Epigenomics 2013; 4:527-35. [PMID: 23130834 DOI: 10.2217/epi.12.51] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
A chronic inflammatory condition of gastric mucosa can facilitate the influx of new stem cells into the stomach. Epigenetic codes, such as DNA methylation, may be responsible for the stable maintenance of epigenetic phenotypes established in the new stomach-adapted stem cells. A number of hypotheses have been made for the role of CpG-island methylation, which is common in the Helicobacter pylori-infected stomach. However, they could not explain the plausible role of CpG-island methylation in the re-establishment of epigenetic phenotypes. These islands are highly repetitive sequences densely methylated throughout the human genome, the so-called parasitic retroelements, which expand a number of cDNA copies with reverse transcriptase. The densely methylated retroelements adjacent to the host genes can form the transitional-CpG sites around gene-control regions that are barely methylated. This review focuses on the putative role of transitional CpG methylation in the adaptive differentiation of new stem cells in the H. pylori-infected stomach.
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Affiliation(s)
- Mun-Gan Rhyu
- Department of Microbiology, College of Medicine, The Catholic University of Korea, 505 Banpo-dong Socho-gu, Seoul 137-701, Korea
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Abstract
LINE-1 (L1) retrotransposons make up a significant portion of human genomes, with an estimated 500,000 copies per genome. Like other retrotransposons, L1 retrotransposons propagate through RNA sequences that are reverse transcribed into DNA sequences, which are integrated into new genomic loci. L1 somatic insertions have the potential to disrupt the transcriptome by inserting into or nearby genes. By mutating genes and playing a role in epigenetic dysregulation, L1 transposons may contribute to tumorigenesis. Studies of the “mobilome” have lagged behind other tumor characterizations at the sequence, transcript, and epigenetic levels. Here, we consider evidence that L1 retrotransposons may sometimes drive human tumorigenesis.
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38
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Sproul D, Meehan RR. Genomic insights into cancer-associated aberrant CpG island hypermethylation. Brief Funct Genomics 2013; 12:174-90. [PMID: 23341493 PMCID: PMC3662888 DOI: 10.1093/bfgp/els063] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Carcinogenesis is thought to occur through a combination of mutational and epimutational events that disrupt key pathways regulating cellular growth and division. The DNA methylomes of cancer cells can exhibit two striking differences from normal cells; a global reduction of DNA methylation levels and the aberrant hypermethylation of some sequences, particularly CpG islands (CGIs). This aberrant hypermethylation is often invoked as a mechanism causing the transcriptional inactivation of tumour suppressor genes that directly drives the carcinogenic process. Here, we review our current understanding of this phenomenon, focusing on how global analysis of cancer methylomes indicates that most affected CGI genes are already silenced prior to aberrant hypermethylation during cancer development. We also discuss how genome-scale analyses of both normal and cancer cells have refined our understanding of the elusive mechanism(s) that may underpin aberrant CGI hypermethylation.
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39
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Akagi K, Li J, Symer DE. How do mammalian transposons induce genetic variation? A conceptual framework: the age, structure, allele frequency, and genome context of transposable elements may define their wide-ranging biological impacts. Bioessays 2013; 35:397-407. [PMID: 23319453 DOI: 10.1002/bies.201200133] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In this essay, we discuss new insights into the wide-ranging impacts of mammalian transposable elements (TE) on gene expression and function. Nearly half of each mammalian genome is comprised of these mobile, repetitive elements. While most TEs are ancient relics, certain classes can move from one chromosomal location to another even now. Indeed, striking recent data show that extensive transposition occurs not only in the germline over evolutionary time, but also in developing somatic tissues and particular human cancers. While occasional germline TE insertions may contribute to genetic variation, many other, similar TEs appear to have little or no impact on neighboring genes. However, the effects of somatic insertions on gene expression and function remain almost completely unknown. We present a conceptual framework to understand how the ages, allele frequencies, molecular structures, and especially the genomic context of mammalian TEs each can influence their various possible functional consequences.
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Affiliation(s)
- Keiko Akagi
- Human Cancer Genetics Program and Department of Molecular Virology, Immunology, and Medical Genetics, The Ohio State University Comprehensive Cancer Center, Columbus, OH, USA
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40
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Tang MH, Varadan V, Kamalakaran S, Zhang MQ, Dimitrova N, Hicks J. Major chromosomal breakpoint intervals in breast cancer co-localize with differentially methylated regions. Front Oncol 2012; 2:197. [PMID: 23293768 PMCID: PMC3530719 DOI: 10.3389/fonc.2012.00197] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 12/05/2012] [Indexed: 01/23/2023] Open
Abstract
Solid tumors exhibit chromosomal rearrangements resulting in gain or loss of multiple chromosomal loci (copy number variation, or CNV), and translocations that occasionally result in the creation of novel chimeric genes. In the case of breast cancer, although most individual tumors each have unique CNV landscape, the breakpoints, as measured over large datasets, appear to be non-randomly distributed in the genome. Breakpoints show a significant regional concentration at genomic loci spanning perhaps several megabases. The proximal cause of these breakpoint concentrations is a subject of speculation, but is, as yet, largely unknown. To shed light on this issue, we have performed a bio-statistical analysis on our previously published data for a set of 119 breast tumors and normal controls (Wiedswang et al., 2003), where each sample has both high-resolution CNV and methylation data. The method examined the distribution of closeness of breakpoint regions with differentially methylated regions (DMR), coupled with additional genomic parameters, such as repeat elements and designated "fragile sites" in the reference genome. Through this analysis, we have identified a set of 93 regional loci called breakpoint enriched DMR (BEDMRs) characterized by altered DNA methylation in cancer compared to normal cells that are associated with frequent breakpoint concentrations within a distance of 1 Mb. BEDMR loci are further associated with local hypomethylation (66%), concentrations of the Alu SINE repeats within 3 Mb (35% of the cases), and tend to occur near a number of cancer related genes such as the protocadherins, AKT1, DUB3, GAB2. Furthermore, BEDMRs seem to deregulate members of the histone gene family and chromatin remodeling factors, e.g., JMJD1B, which might affect the chromatin structure and disrupt coordinate signaling and repair. From this analysis we propose that preference for chromosomal breakpoints is related to genome structure coupled with alterations in DNA methylation and hence, chromatin structure, associated with tumorigenesis.
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Affiliation(s)
- Man-Hung Tang
- Cold Spring Harbor Laboratory Cold Spring Harbor, NY, USA ; Department of Oncology, Clinical Sciences, Lund University Lund, Sweden
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41
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Tanaka Y, Chung L, Park IH. Impact of retrotransposons in pluripotent stem cells. Mol Cells 2012; 34:509-16. [PMID: 23135636 PMCID: PMC3784326 DOI: 10.1007/s10059-012-0242-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 09/28/2012] [Indexed: 01/29/2023] Open
Abstract
Retrotransposons, which constitute approximately 40% of the human genome, have the capacity to 'jump' across the genome. Their mobility contributes to oncogenesis, evolution, and genomic plasticity of the host genome. Induced pluripotent stem cells as well as embryonic stem cells are more susceptible than differentiated cells to genomic aberrations including insertion, deletion and duplication. Recent studies have revealed specific behaviors of retrotransposons in pluripotent cells. Here, we review recent progress in understanding retrotransposons and provide a perspective on the relationship between retrotransposons and genomic variation in pluripotent stem cells.
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Affiliation(s)
- Yoshiaki Tanaka
- Department of Genetics, Yale Stem Cell Center, Yale School of Medicine, 10 Amistad, 201B, New Haven, CT 06520,
USA
| | | | - In-Hyun Park
- Department of Genetics, Yale Stem Cell Center, Yale School of Medicine, 10 Amistad, 201B, New Haven, CT 06520,
USA
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42
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Sproul D, Kitchen RR, Nestor CE, Dixon JM, Sims AH, Harrison DJ, Ramsahoye BH, Meehan RR. Tissue of origin determines cancer-associated CpG island promoter hypermethylation patterns. Genome Biol 2012; 13:R84. [PMID: 23034185 PMCID: PMC3491412 DOI: 10.1186/gb-2012-13-10-r84] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 07/13/2012] [Accepted: 10/03/2012] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Aberrant CpG island promoter DNA hypermethylation is frequently observed in cancer and is believed to contribute to tumor progression by silencing the expression of tumor suppressor genes. Previously, we observed that promoter hypermethylation in breast cancer reflects cell lineage rather than tumor progression and occurs at genes that are already repressed in a lineage-specific manner. To investigate the generality of our observation we analyzed the methylation profiles of 1,154 cancers from 7 different tissue types. RESULTS We find that 1,009 genes are prone to hypermethylation in these 7 types of cancer. Nearly half of these genes varied in their susceptibility to hypermethylation between different cancer types. We show that the expression status of hypermethylation prone genes in the originator tissue determines their propensity to become hypermethylated in cancer; specifically, genes that are normally repressed in a tissue are prone to hypermethylation in cancers derived from that tissue. We also show that the promoter regions of hypermethylation-prone genes are depleted of repetitive elements and that DNA sequence around the same promoters is evolutionarily conserved. We propose that these two characteristics reflect tissue-specific gene promoter architecture regulating the expression of these hypermethylation prone genes in normal tissues. CONCLUSIONS As aberrantly hypermethylated genes are already repressed in pre-cancerous tissue, we suggest that their hypermethylation does not directly contribute to cancer development via silencing. Instead aberrant hypermethylation reflects developmental history and the perturbation of epigenetic mechanisms maintaining these repressed promoters in a hypomethylated state in normal cells.
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Affiliation(s)
- Duncan Sproul
- Breakthrough Breast Cancer Research Unit and Division of Pathology, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Robert R Kitchen
- Breakthrough Breast Cancer Research Unit and Division of Pathology, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
- Yale University School of Medicine, Department of Molecular Biophysics & Biochemistry and Department of Psychiatry, 266 Whitney Ave, New Haven, CT 06511, USA
| | - Colm E Nestor
- Breakthrough Breast Cancer Research Unit and Division of Pathology, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - J Michael Dixon
- Breakthrough Breast Cancer Research Unit and Division of Pathology, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Andrew H Sims
- Breakthrough Breast Cancer Research Unit and Division of Pathology, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - David J Harrison
- Breakthrough Breast Cancer Research Unit and Division of Pathology, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
- University of St Andrews School of Medicine, Medical and Biological Sciences Building, University of St Andrews, North Haugh, St Andrews KY16 9TF, UK
| | - Bernard H Ramsahoye
- Breakthrough Breast Cancer Research Unit and Division of Pathology, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
- Centre for Molecular Medicine, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Richard R Meehan
- Breakthrough Breast Cancer Research Unit and Division of Pathology, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
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Rebollo R, Miceli-Royer K, Zhang Y, Farivar S, Gagnier L, Mager DL. Epigenetic interplay between mouse endogenous retroviruses and host genes. Genome Biol 2012; 13:R89. [PMID: 23034137 PMCID: PMC3491417 DOI: 10.1186/gb-2012-13-10-r89] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 10/03/2012] [Indexed: 11/15/2022] Open
Abstract
Background Transposable elements are often the targets of repressive epigenetic modifications such as DNA methylation that, in theory, have the potential to spread toward nearby genes and induce epigenetic silencing. To better understand the role of DNA methylation in the relationship between transposable elements and genes, we assessed the methylation state of mouse endogenous retroviruses (ERVs) located near genes. Results We found that ERVs of the ETn/MusD family show decreased DNA methylation when near transcription start sites in tissues where the nearby gene is expressed. ERVs belonging to the IAP family, however, are generally heavily methylated, regardless of the genomic environment and the tissue studied. Furthermore, we found full-length ETn and IAP copies that display differential DNA methylation between their two long terminal repeats (LTRs), suggesting that the environment surrounding gene promoters can prevent methylation of the nearby LTR. Spreading from methylated ERV copies to nearby genes was rarely observed, with the regions between the ERVs and genes apparently acting as a boundary, enriched in H3K4me3 and CTCF, which possibly protects the unmethylated gene promoter. Furthermore, the flanking regions of unmethylated ERV copies harbor H3K4me3, consistent with spreading of euchromatin from the host gene toward ERV insertions. Conclusions We have shown that spreading of DNA methylation from ERV copies toward active gene promoters is rare. We provide evidence that genes can be protected from ERV-induced heterochromatin spreading by either blocking the invasion of repressive marks or by spreading euchromatin toward the ERV copy.
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Oki Y, Kondo Y, Yamamoto K, Ogura M, Kasai M, Kobayashi Y, Watanabe T, Uike N, Ohyashiki K, Okamoto SI, Ohnishi K, Tomita A, Miyazaki Y, Tohyama K, Mukai HY, Hotta T, Tomonaga M. Phase I/II study of decitabine in patients with myelodysplastic syndrome: a multi-center study in Japan. Cancer Sci 2012; 103:1839-47. [PMID: 22816487 DOI: 10.1111/j.1349-7006.2012.02386.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 07/10/2012] [Accepted: 07/10/2012] [Indexed: 12/23/2022] Open
Abstract
The management of myelodysplastic syndrome (MDS) remains challenging. We performed a phase I/II study to evaluate the safety and efficacy of decitabine in patients with MDS in Japan. Patients with MDS with red cell transfusion dependence or 5-30% blasts in marrow and with an International Prognostic Scoring System score of intermediate-1 or higher were eligible. Patients received intravenous decitabine at 15 or 20 mg/m(2) daily for 5 days every 4 weeks. A total of 37 patients were enrolled. Three patients received 15 mg/m(2) and experienced no dose limiting toxicity during the first cycle. Thirty-four patients received 20 mg/m(2) . Grade 3 or greater non-hematologic toxicities included cerebral infarction (n = 1), subdural hematoma (n = 1), elevated blood glucose (n = 1), and pulmonary hypertension (n = 1). At 20 mg/m(2) , complete response, partial response, and hematologic improvement were observed in 7 (20.6%), 2 (5.9%), and 7 (20.6%) patients, respectively. Complete cytogenetic response was observed in 30% of evaluable 20 patients. The median number of cycles to clinical response was 4 (range 4-8), and duration of remission was 474+ days (range 294-598+). The 2-year rate of acute myeloid leukemia-free survival was 52%. Correlative studies revealed hypomethylation in multiple genes in peripheral blood cells after treatment. Hypomethylation was generally more profound in CD15 + peripheral blood cells, which reflects myeloid cells, than in peripheral blood mononuclear cells. In summary, decitabine was safe and demonstrated efficacy in Japanese patients with high-risk MDS. This trial was registered at ClinicalTrials.gov (NCT00796003).
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Affiliation(s)
- Yasuhiro Oki
- Department of Hematology and Cell Therapy, Aichi Cancer Center Hospital, Nagoya, Japan.
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45
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Estécio MRH, Gallegos J, Dekmezian M, Lu Y, Liang S, Issa JPJ. SINE retrotransposons cause epigenetic reprogramming of adjacent gene promoters. Mol Cancer Res 2012; 10:1332-42. [PMID: 22952045 DOI: 10.1158/1541-7786.mcr-12-0351] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Almost half of the human genome and as much as 40% of the mouse genome is composed of repetitive DNA sequences. The majority of these repeats are retrotransposons of the SINE and LINE families, and such repeats are generally repressed by epigenetic mechanisms. It has been proposed that these elements can act as methylation centers from which DNA methylation spreads into gene promoters in cancer. Contradictory to a methylation center function, we have found that retrotransposons are enriched near promoter CpG islands that stay methylation-free in cancer. Clearly, it is important to determine which influence, if any, these repetitive elements have on nearby gene promoters. Using an in vitro system, we confirm here that SINE B1 elements can influence the activity of downstream gene promoters, with acquisition of DNA methylation and loss of activating histone marks, thus resulting in a repressed state. SINE sequences themselves did not immediately acquire DNA methylation but were marked by H3K9me2 and H3K27me3. Moreover, our bisulfite sequencing data did not support that gain of DNA methylation in gene promoters occurred by methylation spreading from SINE B1 repeats. Genome-wide analysis of SINE repeats distribution showed that their enrichment is directly correlated with the presence of USF1, USF2, and CTCF binding, proteins with insulator function. In summary, our work supports the concept that SINE repeats interfere negatively with gene expression and that their presence near gene promoters is counter-selected, except when the promoter is protected by an insulator element.
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Affiliation(s)
- Marcos R H Estécio
- Department of Leukemia, The University of Texas MD Anderson Cancer Center, Baylor College of Medicine, Houston, Texas 77030, USA.
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46
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Abstract
Mobile DNAs have had a central role in shaping our genome. More than half of our DNA is comprised of interspersed repeats resulting from replicative copy and paste events of retrotransposons. Although most are fixed, incapable of templating new copies, there are important exceptions to retrotransposon quiescence. De novo insertions cause genetic diseases and cancers, though reliably detecting these occurrences has been difficult. New technologies aimed at uncovering polymorphic insertions reveal that mobile DNAs provide a substantial and dynamic source of structural variation. Key questions going forward include how and how much new transposition events affect human health and disease.
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Affiliation(s)
- Kathleen H Burns
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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47
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Cortessis VK, Thomas DC, Levine AJ, Breton CV, Mack TM, Siegmund KD, Haile RW, Laird PW. Environmental epigenetics: prospects for studying epigenetic mediation of exposure-response relationships. Hum Genet 2012; 131:1565-89. [PMID: 22740325 PMCID: PMC3432200 DOI: 10.1007/s00439-012-1189-8] [Citation(s) in RCA: 194] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 06/07/2012] [Indexed: 12/15/2022]
Abstract
Changes in epigenetic marks such as DNA methylation and histone acetylation are associated with a broad range of disease traits, including cancer, asthma, metabolic disorders, and various reproductive conditions. It seems plausible that changes in epigenetic state may be induced by environmental exposures such as malnutrition, tobacco smoke, air pollutants, metals, organic chemicals, other sources of oxidative stress, and the microbiome, particularly if the exposure occurs during key periods of development. Thus, epigenetic changes could represent an important pathway by which environmental factors influence disease risks, both within individuals and across generations. We discuss some of the challenges in studying epigenetic mediation of pathogenesis and describe some unique opportunities for exploring these phenomena.
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Affiliation(s)
- Victoria K. Cortessis
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, USC Norris Comprehensive Cancer Center, 1441 Eastlake Avenue, Los Angeles, CA 90089 USA
| | - Duncan C. Thomas
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, 2001 N. Soto St., SSB-202F, Los Angeles, CA 90089-9234 USA
| | - A. Joan Levine
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, USC Norris Comprehensive Cancer Center, 1441 Eastlake Avenue, Los Angeles, CA 90089 USA
| | - Carrie V. Breton
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, 2001 N. Soto St., Los Angeles, CA 90089-9234 USA
| | - Thomas M. Mack
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, USC Norris Comprehensive Cancer Center, 1441 Eastlake Avenue, Los Angeles, CA 90089 USA
| | - Kimberly D. Siegmund
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, 2001 N. Soto St., Los Angeles, CA 90089-9234 USA
| | - Robert W. Haile
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, USC Norris Comprehensive Cancer Center, 1441 Eastlake Avenue, Los Angeles, CA 90089 USA
| | - Peter W. Laird
- Departments of Surgery, Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, USC Norris Comprehensive Cancer Center, Epigenome Center, 1441 Eastlake Avenue, Los Angeles, CA 90089-9601 USA
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48
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Jung N, Won JK, Kim BH, Suh KS, Jang JJ, Kang GH. Pharmacological unmasking microarray approach-based discovery of novel DNA methylation markers for hepatocellular carcinoma. J Korean Med Sci 2012; 27:594-604. [PMID: 22690089 PMCID: PMC3369444 DOI: 10.3346/jkms.2012.27.6.594] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 02/23/2012] [Indexed: 12/31/2022] Open
Abstract
DNA methylation is one of the main epigenetic mechanisms and hypermethylation of CpG islands at tumor suppressor genes switches off these genes. To find novel DNA methylation markers in hepatocellular carcinoma (HCC), we performed pharmacological unmasking (treatment with 5-aza-2'-deoxycytidine or trichostatin A) followed by microarray analysis in HCC cell lines. Of the 239 promoter CpG island loci hypermethylated in HCC cell lines (as revealed by methylation-specific PCR), 221 loci were found to be hypermethylated in HCC or nonneoplastic liver tissues. Thirty-three loci showed a 20% higher methylation frequency in tumors than in adjacent nonneoplastic tissues. Correlation of individual cancer-related methylation markers with clinicopathological features of HCC patients (n = 95) revealed that the number of hypermethylated genes in HCC tumors was higher in older than in younger patients. Univariate and multivariate survival analysis revealed that the HIST1H2AE methylation status is closely correlated with the patient's overall survival (P = 0.022 and P = 0.010, respectively). In conclusion, we identified 221 novel DNA methylation markers for HCC. One promising prognostic marker, HIST1H2AE, should be further validated in the prognostication of HCC patients.
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Affiliation(s)
- Namhee Jung
- Laboratory of Epigenetics, Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea
| | - Jae Kyung Won
- Department of Pathology, Seoul National University College of Medicine, Seoul, Korea
| | - Baek-Hui Kim
- Department of General Surgery, Seoul National University College of Medicine, Seoul, Korea
| | - Kyung Suk Suh
- Department of Pathology, Korea University School of Medicine, Seoul, Korea
| | - Ja-June Jang
- Department of Pathology, Seoul National University College of Medicine, Seoul, Korea
| | - Gyeong Hoon Kang
- Laboratory of Epigenetics, Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea
- Department of Pathology, Seoul National University College of Medicine, Seoul, Korea
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49
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Zhang Y, Shu J, Si J, Shen L, Estecio MRH, Issa JPJ. Repetitive elements and enforced transcriptional repression co-operate to enhance DNA methylation spreading into a promoter CpG-island. Nucleic Acids Res 2012; 40:7257-68. [PMID: 22600741 PMCID: PMC3424568 DOI: 10.1093/nar/gks429] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Repression of many tumor suppressor genes in cancer is concurrent with aberrantly increased DNA methylation levels at promoter CpG islands (CGIs). About one-fourth of empirically defined human promoters are surrounded by or contain clustered repetitive elements. It was previously observed that a sharp transition of methylation exists between highly methylated repetitive elements and unmethylated promoter-CGIs in normal tissues. The factors that lead to aberrant CGI hypermethylation in cancer remain poorly understood. Here, we established a site-specific integration system with enforced local transcriptional repression in colorectal cancer cells and monitored the occurrence of initial de novo methylation at specific CG sites adjacent to the CGI of the INSL6 promoter, which could be accelerated by binding a KRAB-containing transcriptional factor. Additional repetitive elements from P16 and RIL (PDLIM4), if situated adjacent to the promoter of INSL6, could confer DNA methylation spreading into the CGI particularly in the setting of KRAB-factor binding. However, a repressive chromatin alone was not sufficient to initiate DNA methylation, which required specific DNA sequences and was integration-site (and/or cell-line) specific. Overall, these results demonstrate a requirement for specific DNA sequences to trigger de novo DNA methylation, and repetitive elements as cis-regulatory factors to cooperate with advanced transcriptional repression in promoting methylation spreading.
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Affiliation(s)
- Yan Zhang
- Department of Leukemia, The University of Texas MD Anderson Cancer Center, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
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50
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De Carvalho DD, Sharma S, You JS, Su SF, Taberlay PC, Kelly TK, Yang X, Liang G, Jones PA. DNA methylation screening identifies driver epigenetic events of cancer cell survival. Cancer Cell 2012; 21:655-667. [PMID: 22624715 PMCID: PMC3395886 DOI: 10.1016/j.ccr.2012.03.045] [Citation(s) in RCA: 195] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Revised: 08/08/2011] [Accepted: 03/27/2012] [Indexed: 12/31/2022]
Abstract
Cancer cells typically exhibit aberrant DNA methylation patterns that can drive malignant transformation. Whether cancer cells are dependent on these abnormal epigenetic modifications remains elusive. We used experimental and bioinformatic approaches to unveil genomic regions that require DNA methylation for survival of cancer cells. First, we surveyed the residual DNA methylation profiles in cancer cells with highly impaired DNA methyltransferases. Then, we clustered these profiles according to their DNA methylation status in primary normal and tumor tissues. Finally, we used gene expression meta-analysis to identify regions that are dependent on DNA methylation-mediated gene silencing. We further showed experimentally that these genes must be silenced by DNA methylation for cancer cell survival, suggesting these are key epigenetic events associated with tumorigenesis.
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Affiliation(s)
- Daniel D De Carvalho
- Department of Urology, Biochemistry and Molecular Biology, University of Southern California/Norris Comprehensive Cancer Center Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9181, USA
| | - Shikhar Sharma
- Department of Urology, Biochemistry and Molecular Biology, University of Southern California/Norris Comprehensive Cancer Center Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9181, USA; Program in Genetic, Molecular and Cellular Biology, University of Southern California/Norris Comprehensive Cancer Center Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9181, USA
| | - Jueng Soo You
- Department of Urology, Biochemistry and Molecular Biology, University of Southern California/Norris Comprehensive Cancer Center Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9181, USA
| | - Sheng-Fang Su
- Department of Urology, Biochemistry and Molecular Biology, University of Southern California/Norris Comprehensive Cancer Center Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9181, USA; Program in Genetic, Molecular and Cellular Biology, University of Southern California/Norris Comprehensive Cancer Center Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9181, USA
| | - Phillippa C Taberlay
- Department of Urology, Biochemistry and Molecular Biology, University of Southern California/Norris Comprehensive Cancer Center Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9181, USA
| | - Theresa K Kelly
- Department of Urology, Biochemistry and Molecular Biology, University of Southern California/Norris Comprehensive Cancer Center Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9181, USA
| | - Xiaojing Yang
- Department of Urology, Biochemistry and Molecular Biology, University of Southern California/Norris Comprehensive Cancer Center Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9181, USA
| | - Gangning Liang
- Department of Urology, Biochemistry and Molecular Biology, University of Southern California/Norris Comprehensive Cancer Center Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9181, USA
| | - Peter A Jones
- Department of Urology, Biochemistry and Molecular Biology, University of Southern California/Norris Comprehensive Cancer Center Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9181, USA.
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