1
|
|
2
|
OMARUDDIN RA, CHAUDHRY MA. Detection of genomic DNA methylation with denaturing high performance liquid chromatography. Hum Cell 2010; 23:41-9. [DOI: 10.1111/j.1749-0774.2010.00084.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
3
|
Sepulveda AR, Jones D, Ogino S, Samowitz W, Gulley ML, Edwards R, Levenson V, Pratt VM, Yang B, Nafa K, Yan L, Vitazka P. CpG methylation analysis--current status of clinical assays and potential applications in molecular diagnostics: a report of the Association for Molecular Pathology. J Mol Diagn 2009; 11:266-78. [PMID: 19541921 DOI: 10.2353/jmoldx.2009.080125] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Methylation of CpG islands in gene promoter regions is a major molecular mechanism of gene silencing and underlies both cancer development and progression. In molecular oncology, testing for the CpG methylation of tissue DNA has emerged as a clinically useful tool for tumor detection, outcome prediction, and treatment selection, as well as for assessing the efficacy of treatment with the use of demethylating agents and monitoring for tumor recurrence. In addition, because CpG methylation occurs early in pre-neoplastic tissues, methylation tests may be useful as markers of cancer risk in patients with either infectious or inflammatory conditions. The Methylation Working Group of the Clinical Practice Committee of the Association of Molecular Pathology has reviewed the current state of clinical testing in this area. We report here our summary of both the advantages and disadvantages of various methods, as well as the needs for standardization and reporting. We then conclude by summarizing the most promising areas for future clinical testing in cancer molecular diagnostics.
Collapse
Affiliation(s)
- Antonia R Sepulveda
- Methylation Working Group of the Association for Molecular Pathology Clinical Practice Committee, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
4
|
Hattermann K, Mehdorn HM, Mentlein R, Schultka S, Held-Feindt J. A methylation-specific and SYBR-green-based quantitative polymerase chain reaction technique for O6-methylguanine DNA methyltransferase promoter methylation analysis. Anal Biochem 2008; 377:62-71. [PMID: 18384736 DOI: 10.1016/j.ab.2008.03.014] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Revised: 03/05/2008] [Accepted: 03/07/2008] [Indexed: 01/28/2023]
Abstract
The O(6)-methylguanine DNA methyltransferase (MGMT) gene encodes a DNA repair enzyme whose activity is a major mechanism of resistance to alkylating drugs in glioblastoma treatment. Hypermethylation of the MGMT promoter is associated with chemosensitivity because it reduces MGMT activity. Here we present a method combining methylation-specific and SYBR-green-based quantitative PCR (MSQP) for MGMT promoter methylation analysis. This highly specific, sensitive, and reproducible method allows the quantification of fully methylated and fully unmethylated MGMT DNA species in terms of percentage. Values are related to standard curves, corrected for DNA input by an internal standard, and calculated in relation to methylated and unmethylated control DNAs as a percentage share. Finally, values are defined relative to the sum of fully methylated and unmethylated MGMT DNA sample amount to obtain percentage of methylated reference and percentage of unmethylated reference results. We have used this technique to investigate MGMT promoter methylation in relation to MGMT mRNA expression in nine tumor cell lines and 15 primary glioblastoma patients. Presented data confirm that this assay is suitable for detection of low amounts of methylated and unmethylated MGMT promoter DNA. Carefully validated quantitative MSQP assays will be useful in both research and clinical molecular diagnosis.
Collapse
Affiliation(s)
- Kirsten Hattermann
- Department of Anatomy, University of Kiel, Olshausenstr. 40, 24098 Kiel, Germany
| | | | | | | | | |
Collapse
|
5
|
Ahmed FE. Colorectal cancer epigenetics: the role of environmental factors and the search for molecular biomarkers. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART C, ENVIRONMENTAL CARCINOGENESIS & ECOTOXICOLOGY REVIEWS 2007; 25:101-54. [PMID: 17558783 DOI: 10.1080/10590500701399184] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
This review presents an evenhanded evaluation of the role of epigenetics in the development of colorectal cancer, and investigates the extent of environmental influences on modulating this disease. Advances in our understanding of chromatin structure, histone modification, transcriptional activity and DNA methylation have lead to an integrated approach to the role of epigenetics in carcinogenesis. Epigenetic mechanisms appear to permit response of individuals to environment through change in gene expression and are involved in inactivating one of the two X chromosomes in women. Epigenetic changes play an important role in development and can also arise stochastically as individuals age. Because epigenetic alterations are potentially reversible, thereby allowing malignant cells to revert to the normal state, there is potential to develop effective strategies to prevent or even reverse this curable cancer. Moreover, because the methylation status of a specific sequence or the pattern of methylation across the genome can now be measured accurately, molecular biomarkers of screening, diagnosis, prognosis, prediction of treatment and those related to risk assessment can be developed using sophisticated molecular genetic technologies. Although in many cases a high sensitivity and specificity of the detection assays has been achieved, there still remains ample room for improvement in areas of sample preparation, assay design and marker selection.
Collapse
Affiliation(s)
- Farid E Ahmed
- Department of Radiation Oncology, Leo W. Jenkins Cancer Center, The Brody School of Medicine, East Carolina University, Greenville, North Carolina 27858, USA.
| |
Collapse
|
6
|
Schumacher A, Petronis A. Epigenetics of Complex Diseases: From General Theory to Laboratory Experiments. Curr Top Microbiol Immunol 2006; 310:81-115. [PMID: 16909908 DOI: 10.1007/3-540-31181-5_6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Despite significant effort, understanding the causes and mechanisms of complex non-Mendelian diseases remains a key challenge. Although numerous molecular genetic linkage and association studies have been conducted in order to explain the heritable predisposition to complex diseases, the resulting data are quite often inconsistent and even controversial. In a similar way, identification of environmental factors causal to a disease is difficult. In this article, a new interpretation of the paradigm of "genes plus environment" is presented in which the emphasis is shifted to epigenetic misregulation as a major etiopathogenic factor. Epigenetic mechanisms are consistent with various non-Mendelian irregularities of complex diseases, such as the existence of clinically indistinguishable sporadic and familial cases, sexual dimorphism, relatively late age of onset and peaks of susceptibility to some diseases, discordance of monozygotic twins and major fluctuations on the course of disease severity. It is also suggested that a substantial portion of phenotypic variance that traditionally has been attributed to environmental effects may result from stochastic epigenetic events in the cell. It is argued that epigenetic strategies, when applied in parallel with the traditional genetic ones, may significantly advance the discovery of etiopathogenic mechanisms of complex diseases. The second part of this chapter is dedicated to a review of laboratory methods for DNA methylation analysis, which may be useful in the study of complex diseases. In this context, epigenetic microarray technologies are emphasized, as it is evident that such technologies will significantly advance epigenetic analyses in complex diseases.
Collapse
Affiliation(s)
- A Schumacher
- The Krembil Family Epigenetics Laboratory, Centre for Addiction and Mental Health, ON, Toronto, Canada
| | | |
Collapse
|
7
|
Ogino S, Kawasaki T, Brahmandam M, Cantor M, Kirkner GJ, Spiegelman D, Makrigiorgos GM, Weisenberger DJ, Laird PW, Loda M, Fuchs CS. Precision and performance characteristics of bisulfite conversion and real-time PCR (MethyLight) for quantitative DNA methylation analysis. J Mol Diagn 2006; 8:209-17. [PMID: 16645207 PMCID: PMC1867588 DOI: 10.2353/jmoldx.2006.050135] [Citation(s) in RCA: 349] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Assays to measure DNA methylation, which are important in epigenetic research and clinical diagnostics, typically rely on conversion of unmethylated cytosine to uracil by sodium bisulfite. However, no study has comprehensively evaluated the precision and performance characteristics of sodium bisulfite conversion and subsequent quantitative methylation assay. We developed quantitative real-time polymerase chain reaction (MethyLight) to measure percentage of methylated reference (PMR, ie, degree of methylation) for the MGMT, MLH1, and CDKN2A (p16) promoters. To measure the precision of bisulfite conversion, we bisulfite-treated seven different aliquots of DNA from each of four paraffin-embedded colon cancer samples. To assess run-to-run variation, we repeated MethyLight five times. Bisulfite-to-bisulfite coefficient of variation (CV) of PMR ranged from 0.10 to 0.38 (mean, 0.21), and run-to-run CV of PMR ranged from 0.046 to 0.60 (mean, 0.31). Interclass correlation coefficients were 0.74 to 0.84 for the three loci, indicating good reproducibility. DNA mixing study with methylated and unmethylated DNA showed good linearity of the assay. Of 272 colorectal cancers evaluated, most showed PMR either <1 or >10, and promoter methylation (PMR >4) was tightly associated with loss of respective protein expression (P < 10(-16)). In conclusion, sodium bisulfite conversion and quantitative MethyLight assays have good precision and linearity and can be effectively used for high-throughput DNA methylation analysis on paraffin-embedded tissue.
Collapse
Affiliation(s)
- Shuji Ogino
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, 75 Francis St., Boston, MA 02115, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Abstract
Epigenetics of human cancer becomes an area of emerging research direction due to a growing understanding of specific epigenetic pathways and rapid development of detection technologies. Aberrant promoter hypermethylation is a prevalent phenonmena in human cancers. Tumor suppressor genes are often hypermethylated due to the increased activity or deregulation of DNMTs. Increasing evidence also reveals that viral genes are one of the key players in regulating DNA methylation. In this review, we will focus on hypermethylation and tumor suppressor gene silencing and the signal pathways that are involved, particularly in cancers closely associated with the hepatitis B virus, simian virus 40 (SV40), and Epstein-Barr virus. In addition, we will discuss current technologies for genome-wide detection of epigenetically regulated targets, which allow for systematic DNA hypermethylation analysis. The study of epigenetic changes should provide a global view of gene profile in cancer, and epigenetic markers could be used for early detection, prognosis, and therapy of cancer.
Collapse
Affiliation(s)
- Hsin Pai Li
- Graduate Institute of Basic Medical Sciences, Chang Gung University, Kwei-shan, Taoyuan, Taiwan
| | | | | |
Collapse
|
9
|
Abstract
Cancer arises due to the accumulation of DNA modifications that give cells a selective growth advantage. One common DNA modification is promoter hypermethylation associated with loss of expression of a tumor suppressor gene. The methylation status of a specific sequence or the pattern of methylation across the genome can be readily measured, and these sequences and analytical methods are being rapidly developed for molecular diagnostic applications. Detection of certain methylation events can be used for early detection of tumors, and analysis of patterns of methylation across the genome might provide information on disease subtype, aggressiveness, and treatment response. DNA methylation-based molecular diagnostic assays are particularly attractive because of the stability of the target analyte (DNA) and the potential sensitivity of the assays. As the field matures, methylation-based assays will make a major contribution to the field of molecular diagnostics, providing tools to fill unmet needs in current diagnostic and treatment plans for many types of cancer.
Collapse
|
10
|
Handa V, Jeltsch A. Anomalous mobility of polymerase chain reaction products after bisulfite treatment of DNA. Anal Biochem 2004; 333:196-8. [PMID: 15351297 DOI: 10.1016/j.ab.2004.06.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2004] [Indexed: 11/22/2022]
Affiliation(s)
- Vikas Handa
- Institut für Biochemie, FB 8, Justus-Liebig-Universität, Heinrich-Buff-Ring 58, 35392 Giessen, Germany
| | | |
Collapse
|
11
|
Abstract
The past few years have seen an explosion of interest in the epigenetics of cancer. This has been a consequence of both the exciting coalescence of the chromatin and DNA methylation fields, and the realization that DNA methylation changes are involved in human malignancies. The ubiquity of DNA methylation changes has opened the way to a host of innovative diagnostic and therapeutic strategies. Recent advances attest to the great promise of DNA methylation markers as powerful future tools in the clinic.
Collapse
Affiliation(s)
- Peter W Laird
- University of Southern California, Norris Comprehensive Cancer Center, Room 6418, 1441 Eastlake Avenue, Los Angeles, California 90089-9176, USA.
| |
Collapse
|