title: Comprehensive DNA Methylation and Mutation Analyses Reveal a Methylation Signature in Colorectal Sessile Serrated Adenomas.
abstract: Colorectal sessile serrated adenomas (SSA) are hypothesized to be precursor lesions of an alternative, serrated pathway of colorectal cancer, abundant in genes with aberrant promoter DNA hypermethylation. In our present pilot study, we explored DNA methylation profiles and examined selected gene mutations in SSA. Biopsy samples from patients undergoing screening colonoscopy were obtained during endoscopic examination. After DNA isolation and quality analysis, SSAs (n = 4) and healthy controls (n = 5) were chosen for further analysis. DNA methylation status of 96 candidate genes was screened by q(RT)PCR using Methyl-Profiler PCR array system. Amplicons for 12 gene mutations were sequenced by GS Junior Instrument using ligated and barcoded adaptors. Analysis of DNA methylation revealed 9 hypermethylated genes in both normal and SSA samples. 12 genes (CALCA, DKK2, GALR2, OPCML, PCDH10, SFRP1, SFRP2, SLIT3, SST, TAC1, VIM, WIF1) were hypermethylated in all SSAs and 2 additional genes (BNC1 and PDLIM4) were hypermethylated in 3 out of 4 SSAs, but in none of the normal samples. 2 SSAs exhibited BRAF mutation and synchronous MLH1 hypermethylation and were microsatellite instable by immunohistochemical analysis. Our combined mutation and DNA methylation analysis revealed that there is a common DNA methylation signature present in pre-neoplastic SSAs. This study advocates for the use of DNA methylation as a potential biomarker for the detection of SSA; however, further investigation is needed to better characterize the molecular background of these newly recognized colorectal lesions.
authors.affiliation: 2nd Department of Medicine, Semmelweis University, Szentkirályi utca 46, Budapest, 1088, Hungary. arpad.patai@gmail.com.
authors.forename: Árpád V
authors.initials: ÁV
authors.lastname: Patai
authors.affiliation: 2nd Department of Medicine, Semmelweis University, Szentkirályi utca 46, Budapest, 1088, Hungary.
authors.forename: Barbara Kinga
authors.initials: BK
authors.lastname: Barták
authors.affiliation: Molecular Medicine Research Group, Hungarian Academy of Sciences, Roosevelt tér 9, Budapest, 1051, Hungary.
authors.forename: Bálint
authors.initials: B
authors.lastname: Péterfia
authors.affiliation: 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Üllői út 26, Budapest, 1085, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Micsik
authors.affiliation: 2nd Department of Medicine, Semmelweis University, Szentkirályi utca 46, Budapest, 1088, Hungary.
authors.forename: Réka
authors.initials: R
authors.lastname: Horváth
authors.affiliation: 2nd Department of Medicine, Semmelweis University, Szentkirályi utca 46, Budapest, 1088, Hungary.
authors.forename: Csaba
authors.initials: C
authors.lastname: Sumánszki
authors.affiliation: 2nd Department of Medicine, Semmelweis University, Szentkirályi utca 46, Budapest, 1088, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Péter
authors.affiliation: Department of Gastroenterology and Internal Medicine, Markusovszky University Teaching Hospital, Markusovszky Lajos utca 5, Szombathely, 9700, Hungary.
authors.forename: Árpád
authors.initials: Á
authors.lastname: Patai
authors.affiliation: Molecular Medicine Research Group, Hungarian Academy of Sciences, Roosevelt tér 9, Budapest, 1051, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Valcz
authors.affiliation: 2nd Department of Medicine, Semmelweis University, Szentkirályi utca 46, Budapest, 1088, Hungary.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Kalmár
authors.affiliation: 2nd Department of Medicine, Semmelweis University, Szentkirályi utca 46, Budapest, 1088, Hungary.
authors.forename: Kinga
authors.initials: K
authors.lastname: Tóth
authors.affiliation: 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Üllői út 26, Budapest, 1085, Hungary.
authors.forename: Tibor
authors.initials: T
authors.lastname: Krenács
authors.affiliation: 2nd Department of Medicine, Semmelweis University, Szentkirályi utca 46, Budapest, 1088, Hungary.|Molecular Medicine Research Group, Hungarian Academy of Sciences, Roosevelt tér 9, Budapest, 1051, Hungary.
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Tulassay
authors.affiliation: 2nd Department of Medicine, Semmelweis University, Szentkirályi utca 46, Budapest, 1088, Hungary.|Molecular Medicine Research Group, Hungarian Academy of Sciences, Roosevelt tér 9, Budapest, 1051, Hungary.
authors.forename: Béla
authors.initials: B
authors.lastname: Molnár
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000236:Adenoma / Q000235:genetics*; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000235:genetics*; D019175:DNA Methylation / Q000235:genetics*; D004252:DNA Mutational Analysis / Q000379:methods; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006801:Humans; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics; D010865:Pilot Projects; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D009687:Nuclear Proteins; D048493:Proto-Oncogene Proteins B-raf
keywords: Biomarker; DNA methylation; Mutation; Serrated polyp; Sessile serrated adenoma; Traditional serrated adenoma