Identification of Endometrial Cancer Methylation Features Using a Combined
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Identification of endometrial cancer methylation features using a combined methylation analysis method DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Michael P Trimarchi B.S. Biomedical Sciences Graduate Program The Ohio State University 2016 Dissertation Committee: Joanna L Groden, Advisor Paul Goodfellow Ralf A. Bundschuh Jeffrey Parvin Pearlly Yan Copyrighted by Michael P Trimarchi 2016 Abstract Introduction: DNA methylation is a stable epigenetic mark that is frequently altered in tumors. DNA methylation marks are attractive biomarkers for disease states given the stability of DNA methylation in living cells and in biologic specimens. Widespread accumulation of methylation in regulatory elements in some cancers (termed the CpG island methylator phenotype, CIMP) can play an important role in tumorigenesis. High resolution assessment of CIMP for the entire genome, however, remains cost prohibitive and requires quantities of DNA that are not available for many tissue samples of interest. Genome-wide scans of methylation have been undertaken for large numbers of tumors, and higher resolution analyses have been performed for a limited number of cancer specimens. Yet methods for analyzing these large datasets and integrating findings from different studies have not been fully developed. An approach was developed to profile CIMP by combining the strengths of two different methylome profiling techniques. Methods: Methylomes for 76 primary endometrial cancer and 12 normal endometrial samples were generated using methylated fragment capture and second generation sequencing (MethylCap-seq). Publically available data from The Cancer Genome Atlas (TCGA) for 203 endometrial cancers, analyzed using the Infinium HumanMethylation 450 beadchip, were compared to the MethylCap-seq data. A MethylCap-seq quality control module was ii developed to exclude sequencing samples with poor-quality methylation data from analysis. Additional MethylCap-seq datasets were also used to develop and validate the quality control module. Results: Analysis of total methylation in promoter CpG islands (CGIs) identified a subset of tumors with a methylator phenotype. I developed a 13- region methylation signature associated with a “hypermethylator state” using a training set of five highly methylated and eight lowly methylated tumors. The signature was validated using data from TCGA. High signature methylation score was associated with mismatch repair deficiency, high mutation rate, and low somatic copy number alteration in TCGA test set. In addition, the methylation signature distinguished >90% of endometrioid endometrial tumors from normal controls in the test set. Furthermore, classification of tumors by signature methylation score proved highly robust, showing good agreement with previously published methylation clusters for the test set as well as consistent ranking of tumors across alternative signatures. Conclusion: I identified a methylation signature for a “hypermethylator phenotype” in endometrial cancer and developed methods that could prove useful for identifying extreme methylation phenotypes in other cancers. iii Acknowledgments My sincere thanks to my committee and my former advisor Tim H.M. Huang for making this project possible, as well as the current and former members of the Yan and Groden labs. Special thanks to Paul Goodfellow for helping reorient the project after my former advisor left, and to Ralf Bundschuh for his guidance in data analysis. iv Vita June 2002 ............................................... North Olmsted High School June 2006 ............................................... B.S. Microbiology, Minor in Chemistry, The Ohio State University June 2007 to present ............................. Graduate Research Associate, Biomedical Sciences Graduate Program, The Ohio State University Publications 2016 Michael P Trimarchi, Pearlly Yan, Joanna Groden, Ralf Bundschuh, Paul Goodfellow. Identification of endometrial cancer methylation features using a combined methylation analysis method. Manuscript in preparation. 2012 Michael P Trimarchi, Mark Murphy, David Frankhouser, Benjamin AT Rodriguez, John Curfman, Guido Marcucci, Pearlly Yan, Ralf Bundschuh. Enrichment-based DNA methylation analysis using next-generation sequencing: sample exclusion, estimating changes in global methylation, and the contribution of replicate lanes. BMC Genomics 2012, 13(Suppl 8):S6 (17 December 2012). v 2012 Rodriguez B, Tam HH, Frankhouser D, Trimarchi M, Murphy M, Kuo C, Parikh D, Ball B, Schwind S, Curfman J, Blum W, Marcucci G, Yan P, Bundschuh R. A Scalable, Flexible Workflow for MethylCap-Seq Data Analysis. BMC Genomics 2012, 13(Suppl 6):S14 (26 October 2012). 2012 Yan P, Frankhouser D, Murphy M, Tam HH, Rodriguez B, Curfman J, Trimarchi M, Geyer S, Wu YZ, Whitman SP, Metzeler K, Walker A, Klisovic R, Jacob S, Grever MR, Byrd JC, Bloomfield CD, Garzon R, Blum W, Caligiuri MA, Bundschuh R, Marcucci G. Genome-wide methylation profiling in decitabine- treated patients with acute myeloid leukemia. Blood. 2012 Jul 11. 2011 Trimarchi MP, Mouangsavanh M, Huang TH., Cancer epigenetics: a perspective on the role of DNA methylation in acquired endocrine resistance. Chin J Cancer. 2011 Nov;30(11):749-56. 2010 Cottrell, C. E., Bir, N., Varga, E., Alvarez, C. E., Bouyain, S., Zernzach, R., Thrush, D. L., Evans, J., Trimarchi, M., Butter, E. M., Cunningham, D., Gastier-Foster, J. M., McBride, K. L. and Herman, G. E. Contactin 4 as an autism susceptibility locus. Autism Res. 2011 Jun;4(3):189-99. vi Fields of Study Major Field: Biomedical Sciences Specialization: Cancer Research Interdisciplinary Specialization: Biomedical, Clinical & Translational Sciences vii Table of Contents Abstract ............................................................................................................ ii Acknowledgments ........................................................................................... iv Vita .................................................................................................................. v List of Figures ................................................................................................. xii List of Tables ................................................................................................. xiv Chapter 1. Background .................................................................................... 1 I. Epigenetics in cancer, with a focus on DNA methylation .......................... 1 Chromatin model ...................................................................................... 1 DNA methylation ...................................................................................... 1 DNA methylation in cancer COMMENT: perhaps this is a better place for you to refer to the You and Jones Cancer Cell review. ....................... 2 Histone modifications ............................................................................... 3 DNA methylation interaction with histone modifications ........................... 4 DNA methylation as a biomarker and therapeutic target .......................... 5 II. Methylome Profiling ................................................................................. 6 Analysis methods ..................................................................................... 6 Methylome Profiling: The Biology ........................................................... 13 viii Chapter 2. Thesis Rationale and Research Objectives ................................ 19 Chapter 3. Enrichment-based DNA methylation analysis using next- generation sequencing: quality control, estimating changes in global methylation and the effects of increased sequencing depth. ......................... 21 I. Introduction ............................................................................................ 21 II. Results and Discussion ......................................................................... 23 Quality control exclusion criteria reduce noise in methylation signal and improve analytical power. ....................................................................... 23 The effect of additional sequencing lanes on quality control metrics ...... 27 The global methylation indicator (GMI) correlates inversely with an in vitro methylated tracer sequence. .................................................................. 31 III. Methods ............................................................................................... 34 Patient samples ...................................................................................... 34 Methylated-DNA capture (MethylCap-seq) ............................................. 35 MethylCap-seq experimental quality control and exclusion criteria ........ 36 Standard sequence file processing and alignment ................................. 37 Standard global methylation analysis workflow ...................................... 37 Calculation of noise in methylation signal ............................................... 38 Calculation of the Global Methylation Indicator (GMI) ............................ 39 Assessment of methylated fragment enrichment using an in vitro methylated construct .............................................................................. 39 ix IV. Conclusions ......................................................................................... 40 Chapter 4. Identification of endometrial cancer