title: p53 expression, K-ras gene mutation and microsatellite instability in gastric B-cell lymphomas.
abstract: OBJECTIVE
  Genetic mechanisms involved in the development of gastric B-cell lymphomas remain unclear. The aim of the present study was to clarify the roles of mutations of the p53 and K-ras genes, and microsatellite instability (MSI) in the development of gastric B-cell lymphomas.
  
  
  METHODS
  We investigated p53 immunoreactivity, mutations of the K-ras gene, and MSI in 27 gastric marginal zone B-cell lymphomas of mucosa-associated lymphoid tissue type (MZBCL) and 24 diffuse large B-cell lymphomas (DLBCL). p53 immunoreactivity was examined using a monoclonal antibody, DO-7. Mutation of the K-ras gene was detected by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis. MSI was examined at five microsatellite loci with a microsatellite assay. Cases were classified as having high-frequency MSI (MSI-H) (>/= 2 loci showing instability), low-frequency MSI (MSI-L) (only one locus showing instability), or as microsatellite stable.
  
  
  RESULTS
  p53 immunoreactivity was detected in 1 of 16 (6%) MZBCL and 8 of 19 (42%) DLBCL. Frequency of p53 immunoreactivity in DLBCL was significantly higher than that in MZBCL (P = 0.018). MSI-H was detected only in 1 of 20 (5%) DLBCL. None of the cases examined showed mutation of the K-ras gene.
  
  
  CONCLUSIONS
  These data suggest that mutations of the p53 gene may play an important role in the development of gastric DLBCL, and that mutations of the K-ras gene and MSI may be involved in little part of the development of gastric B-cell lymphomas.
authors.affiliation: Health Service Center, Hiroshima University, 1-7-1 Kagamiyama, Higashihiroshima 739-8521, Japan. tohiyama@hiroshima-u.ac.jp
authors.forename: Toru
authors.initials: T
authors.lastname: Hiyama
authors.forename: Shinji
authors.initials: S
authors.lastname: Tanaka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Masuda
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Shima
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kose
authors.forename: Handan
authors.initials: H
authors.lastname: Tuncel
authors.forename: Masanori
authors.initials: M
authors.lastname: Ito
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kitadai
authors.forename: Masaharu
authors.initials: M
authors.lastname: Sumii
authors.forename: Naomi
authors.initials: N
authors.lastname: Uemura
authors.forename: Masaharu
authors.initials: M
authors.lastname: Yoshihara
authors.forename: Fumio
authors.initials: F
authors.lastname: Shimamoto
authors.forename: Ken
authors.initials: K
authors.lastname: Haruma
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Chayama
mesh_terms: D043171:Chromosomal Instability / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D016158:Genes, p53 / Q000235:genetics*; D011905:Genes, ras / Q000235:genetics*; D006801:Humans; D016393:Lymphoma, B-Cell / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D013274:Stomach Neoplasms / Q000235:genetics*