title: IGF2 differentially methylated region hypomethylation in relation to pathological and molecular features of serrated lesions.
abstract: OBJECTIVE
  To investigate insulin-like growth factor 2 (IGF2) differentially methylated region (DMR)0 hypomethylation in relation to clinicopathological and molecular features in colorectal serrated lesions.
  
  
  METHODS
  To accurately analyze the association between the histological types and molecular features of each type of serrated lesion, we consecutively collected 1386 formalin-fixed paraffin-embedded tissue specimens that comprised all histological types [hyperplastic polyps (HPs, n = 121), sessile serrated adenomas (SSAs, n = 132), traditional serrated adenomas (TSAs, n = 111), non-serrated adenomas (n = 195), and colorectal cancers (CRCs, n = 827)]. We evaluated the methylation levels of IGF2 DMR0 and long interspersed nucleotide element-1 (LINE-1) in HPs (n = 115), SSAs (n = 120), SSAs with cytological dysplasia (n = 10), TSAs (n = 91), TSAs with high-grade dysplasia (HGD) (n = 15), non-serrated adenomas (n = 80), non-serrated adenomas with HGD (n = 105), and CRCs (n = 794). For the accurate quantification of the relative methylation levels (scale 0%-100%) of IGF2 DMR0 and LINE-1, we used bisulfite pyrosequencing method. Tumor specimens were analyzed for microsatellite instability, KRAS (codons 12 and 13), BRAF (V600E), and PIK3CA (exons 9 and 20) mutations; MLH1 and MGMT methylation; and IGF2 expression by immunohistochemistry.
  
  
  RESULTS
  The distribution of the IGF2 DMR0 methylation level in 351 serrated lesions and 185 non-serrated adenomas (with or without HGD) was as follows: mean 61.7, median 62.5, SD 18.0, range 5.0-99.0, interquartile range 49.5-74.4. The IGF2 DMR0 methylation level was divided into quartiles (Q1 ≥ 74.5, Q2 62.6-74.4, Q3 49.6-62.5, Q4 ≤ 49.5) for further analysis. With regard to the histological type, the IGF2 DMR0 methylation levels of SSAs (mean ± SD, 73.1 ± 12.3) were significantly higher than those of HPs (61.9 ± 20.5), TSAs (61.6 ± 19.6), and non-serrated adenomas (59.0 ± 15.8) (P < 0.0001). The IGF2 DMR0 methylation level was inversely correlated with the IGF2 expression level (r = -0.21, P = 0.0051). IGF2 DMR0 hypomethylation was less frequently detected in SSAs compared with HPs, TSAs, and non-serrated adenomas (P < 0.0001). Multivariate logistic regression analysis also showed that IGF2 DMR0 hypomethylation was inversely associated with SSAs (P < 0.0001). The methylation levels of IGF2 DMR0 and LINE-1 in TSAs with HGD (50.2 ± 18.7 and 55.7 ± 5.4, respectively) were significantly lower than those in TSAs (61.6 ± 19.6 and 58.8 ± 4.7, respectively) (IGF2 DMR0, P = 0.038; LINE-1, P = 0.024).
  
  
  CONCLUSIONS
  IGF2 DMR0 hypomethylation may be an infrequent epigenetic alteration in the SSA pathway. Hypomethylation of IGF2 DMR0 and LINE-1 may play a role in TSA pathway progression.
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Naito
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Nosho
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Ito
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Hisayoshi
authors.initials: H
authors.lastname: Igarashi
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Mitsuhashi
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Yoshii
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Hironori
authors.initials: H
authors.lastname: Aoki
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Nomura
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Sukawa
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Yamamoto
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Adachi
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Masao
authors.initials: M
authors.lastname: Hosokawa
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Fujita
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Toshinao
authors.initials: T
authors.lastname: Takenouchi
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Reo
authors.initials: R
authors.lastname: Maruyama
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Hiromu
authors.initials: H
authors.lastname: Suzuki
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Baba
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Kohzoh
authors.initials: K
authors.lastname: Imai
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yamamoto
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Ogino
authors.affiliation: Takafumi Naito, Katsuhiko Nosho, Miki Ito, Hisayoshi Igarashi, Kei Mitsuhashi, Eiichiro Yamamoto, Yasushi Adachi, Yasuhisa Shinomura, Department of Gastroenterology, Rheumatology and Clinical Immunology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan.
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Shinomura
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000236:Adenoma / Q000737:chemistry / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis / Q000235:genetics*; D016009:Chi-Square Distribution; D058534:Class I Phosphatidylinositol 3-Kinases; D015179:Colorectal Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000235:genetics; D045643:DNA Repair Enzymes / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020022:Genetic Predisposition to Disease; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000032:analysis / Q000235:genetics*; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D020084:Long Interspersed Nucleotide Elements; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D015999:Multivariate Analysis; D000070957:MutL Protein Homolog 1; D009687:Nuclear Proteins / Q000235:genetics; D010641:Phenotype; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics; D011379:Prognosis; D011518:Proto-Oncogene Proteins / Q000235:genetics; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D025521:Tumor Suppressor Proteins / Q000235:genetics; D018631:ras Proteins / Q000235:genetics
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D014408:Biomarkers, Tumor; C035170:IGF2 protein, human; C117307:KRAS protein, human; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins; D007335:Insulin-Like Growth Factor II; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D000070957:MutL Protein Homolog 1; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins; D045643:DNA Repair Enzymes
keywords: BRAF; Colon polyp; Colorectal neoplasia; Colorectum; Genome; Insulin-like growth factor; Long interspersed nucleotide element-1; Microsatellite instability; Serrated pathway
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