title: Analysis of molecular alterations in laterally spreading tumors of the colorectum.
abstract: BACKGROUND
  Colorectal laterally spreading tumors (LSTs) are classified into LST-Gs and LST-NGs, according to macroscopic findings. In the present study, we determined the genetic and epigenetic alterations within colorectal LSTs and protruding adenomas.
  
  
  METHODS
  A crypt isolation method was used to isolate DNA from tumors and normal glands of 73 macroscopically verified colorectal LSTs (histologically defined adenomas; 38 LST-Gs and 35 LST-NGs) and 36 protruding adenomas. The DNA was processed using polymerase chain reaction (PCR) microsatellite assays, single-strand conformation polymorphism (SSCP) assays, and pyrosequencing to detect chromosomal allelic imbalance (AI), mutations in APC, KRAS, and TP53, and the methylation of MLH1, MGMT, CDKN2A, HPP1, RASSF2A, SFRP1, DKK1, ZFP64, and SALL4 genes. In addition, methylation status was examined using the following set of markers: MIN1, MINT2, MINT31, MLH1, and CDKN2A (with classification of negative/low and high). Microsatellite instability (MSI) was also examined.
  
  
  RESULTS
  5q AI and methylation of the SFRP1 and SALL4 genes were common molecular events in both LST-Gs and LST-NGs. Neither MSI nor mutations in BRAF ware observed in the LSTs. TP53 mutations were rarely found in LSTs. The frequencies of KRAS and APC mutations and the methylation levels of ZFP64, RASSF2A, and HPP1 genes were significantly higher in LST-Gs than in LST-NGs. Protruding adenomas showed alterations common to LST-Gs. Negative/low methylation status was common among the three types of tumors.
  
  
  CONCLUSIONS
  Combined genetic and epigenetic data suggested that the molecular mechanisms of tumorigenesis were different between LST-Gs and LST-NGs.
authors.affiliation: Department of Molecular Diagnostic Pathology, School of Medicine, Iwate Medical University, 19-1, Morioka, 020-8505, Japan. tsugai@iwate-med.ac.jp.
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Sugai
authors.affiliation: Department of Pharmacodynamics and Molecular Genetics, School of Pharmacy, Iwate Medical University, 19-1, Morioka, 020-8505, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Habano
authors.affiliation: Division of Gastroenterology, Akita Red Cross Hospital, Kamikitatesaruta, Akita, 010-1406, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Takagi
authors.affiliation: Division of Gastroenterology, Akita Red Cross Hospital, Kamikitatesaruta, Akita, 010-1406, Japan.
authors.forename: Hiroo
authors.initials: H
authors.lastname: Yamano
authors.affiliation: Department of Molecular Diagnostic Pathology, School of Medicine, Iwate Medical University, 19-1, Morioka, 020-8505, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Eizuka
authors.affiliation: Department of Molecular Diagnostic Pathology, School of Medicine, Iwate Medical University, 19-1, Morioka, 020-8505, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Arakawa
authors.affiliation: Department of Molecular Diagnostic Pathology, School of Medicine, Iwate Medical University, 19-1, Morioka, 020-8505, Japan.
authors.forename: Yayoi
authors.initials: Y
authors.lastname: Takahashi
authors.affiliation: Department of Molecular Biology, Sapporo Medical University, Minami1jonishi 1-19, Chuo-ku, Sapporo, Hokkaido, 060-0061, Japan.|Department of First Internal Medicine, Sapporo Medical University, Minami1jonishi 1-19, Chuo-ku, Sapporo, Hokkaido, 060-0061, Japan.
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Yamamoto
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Iwate Medical University, 19-1, Morioka, 020-8505, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kawasaki
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Iwate Medical University, 19-1, Morioka, 020-8505, Japan.
authors.forename: Syunichi
authors.initials: S
authors.lastname: Yanai
authors.affiliation: Department of Molecular Diagnostic Pathology, School of Medicine, Iwate Medical University, 19-1, Morioka, 020-8505, Japan.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Ishida
authors.affiliation: Department of Molecular Biology, Sapporo Medical University, Minami1jonishi 1-19, Chuo-ku, Sapporo, Hokkaido, 060-0061, Japan.
authors.forename: Hiromu
authors.initials: H
authors.lastname: Suzuki
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Iwate Medical University, 19-1, Morioka, 020-8505, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Matsumoto
mesh_terms: D000236:Adenoma / Q000235:genetics / Q000473:pathology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000235:genetics / Q000473:pathology*; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000235:genetics*; D044127:Epigenesis, Genetic; D005260:Female; D006801:Humans; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D009154:Mutation; D016133:Polymerase Chain Reaction
chemical_list: D004273:DNA, Neoplasm
keywords: APC; Colon; KRAS; Laterally spreading tumor; Loss of heterozygosity; Methylation