Tamotsu Sugai1, Ryo Sugimoto2, Wataru Habano3, Masaki Endoh4, Makoto Eizuka2, Koudai Tsuchida2, Eiichiro Yamamoto5, Keisuke Kawasaki4, Syunichi Yanai4, Takayuki Matsumoto4, Hiromu Suzuki5. 1. Department of Molecular Diagnostic Pathology, School of Medicine, Iwate Medical University, 19-1, Morioka, 020-8505, Japan. tsugai@cocoa.ocn.ne.jp. 2. Department of Molecular Diagnostic Pathology, School of Medicine, Iwate Medical University, 19-1, Morioka, 020-8505, Japan. 3. Department of Pharmacodynamics and Molecular Genetics, School of Pharmacy, Iwate Medical University, Morioka, Japan. 4. Division of Gastroenterology, Department of Internal Medicine, Iwate Medical University, Morioka, Japan. 5. Department of Molecular Biology, Sapporo Medical University School of Medicine, Sapporo, Japan.
Abstract
BACKGROUND: Although genetic alterations in patients with advanced gastric cancer have been extensively studied, those in patients with intramucosal neoplasia (IMN) are still poorly understood. METHODS: We evaluated genetic differences in 158 IMNs, including 51 low-grade dysplasias, 58 high-grade dysplasias (HGDs), 30 intramucosal cancers (IMCs), and 19 mixed tumors (composed of IMC and HGD within the same tumor), using PCR-based microsatellite analysis [allelic imbalance (AI) and microsatellite instability (MSI)]. We classified the DNA methylation status as a hypermethylated epigenome, a moderately methylated epigenome, or a hypomethylated epigenome. In addition, p53 overexpression, β-catenin nuclear localization, and mucin expression were also examined. RESULTS: From cluster analysis, the IMNs examined were categorized into four subgroups as follows. Tumors in subgroup 1 were characterized by MSI-high status, a hypermethylated epigenome, and loss or reduction of expression of MLH-1. Tumors in subgroup 2 showed a mixed pattern consisting of AI and MSI. In contrast, tumors in subgroup 3, which showed accumulation of multiple AIs, were closely associated with HGD, IMC, or mixed tumor and exhibited nuclear expression of β-catenin. Tumors in subgroup 4, which were generally low-grade dysplasias, exhibited a low frequency of AIs and no MSI. Although the mucin phenotype was not correlated with any subgroup, expression of mucin was associated with some subgroups. Overexpression of p53 was common in all subgroups. CONCLUSION: The approach described herein was useful for studying genetic differences in IMNs. In addition, we suggest that stratification of genetic differences may help to identify genetic molecular profiles in IMNs.
BACKGROUND: Although genetic alterations in patients with advanced gastric cancer have been extensively studied, those in patients with intramucosal neoplasia (IMN) are still poorly understood. METHODS: We evaluated genetic differences in 158 IMNs, including 51 low-grade dysplasias, 58 high-grade dysplasias (HGDs), 30 intramucosal cancers (IMCs), and 19 mixed tumors (composed of IMC and HGD within the same tumor), using PCR-based microsatellite analysis [allelic imbalance (AI) and microsatellite instability (MSI)]. We classified the DNA methylation status as a hypermethylated epigenome, a moderately methylated epigenome, or a hypomethylated epigenome. In addition, p53 overexpression, β-catenin nuclear localization, and mucin expression were also examined. RESULTS: From cluster analysis, the IMNs examined were categorized into four subgroups as follows. Tumors in subgroup 1 were characterized by MSI-high status, a hypermethylated epigenome, and loss or reduction of expression of MLH-1. Tumors in subgroup 2 showed a mixed pattern consisting of AI and MSI. In contrast, tumors in subgroup 3, which showed accumulation of multiple AIs, were closely associated with HGD, IMC, or mixed tumor and exhibited nuclear expression of β-catenin. Tumors in subgroup 4, which were generally low-grade dysplasias, exhibited a low frequency of AIs and no MSI. Although the mucin phenotype was not correlated with any subgroup, expression of mucin was associated with some subgroups. Overexpression of p53 was common in all subgroups. CONCLUSION: The approach described herein was useful for studying genetic differences in IMNs. In addition, we suggest that stratification of genetic differences may help to identify genetic molecular profiles in IMNs.
Authors: T Sugai; W Habano; S Nakamura; H Sato; N Uesugi; H Takahashi; Y Jiao; T Yoshida; C Itoh Journal: Int J Cancer Date: 2000-11-15 Impact factor: 7.396
Authors: C R Boland; S N Thibodeau; S R Hamilton; D Sidransky; J R Eshleman; R W Burt; S J Meltzer; M A Rodriguez-Bigas; R Fodde; G N Ranzani; S Srivastava Journal: Cancer Res Date: 1998-11-15 Impact factor: 12.701