title: K-ras mutation in helicobacter pylori-associated chronic gastritis in patients with and without gastric cancer.
abstract: Mutations of an oncogene, K-ras, are associated with the development and progression of many types of human cancer. To elucidate the significance of K-ras mutations in gastric carcinogenesis, we examined K-ras mutations in gastric cancers and in Helicobacter pylori-associated chronic gastritis (H. pylori-CG), which is associated with an increased risk for the gastric cancer development. Specimens of gastric cancer and H. pylori-CG were obtained from 64 gastric cancer patients with H. pylori-CG, 99 cancer-free H. pylori-CG patients and 30 H. pylori-negative healthy subjects. K-ras mutations were examined by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP), followed by DNA sequencing analysis. K-ras mutations were detected in 4 of 48 (8.3%) gastric cancers, in 10 of 163 (6.1%) H. pylori-CG and none of the 30 H. pylori-negative healthy subjects. In the gastric cancer patients, mutated K-ras was detected in differentiated type cancers but not in any of the undifferentiated type cancers. K-ras mutations in H. pylori-CG were significantly more frequent in gastric cancer patients than in cancer-free patients (10.9% vs. 3.0%, p = 0.044). In addition, K-ras mutations in H. pylori-CG were significantly more frequent in patients with K-ras mutated gastric cancer than in patients with K-ras unmutated gastric cancer (50.0% vs. 3.7%, p = 0.037). These data suggest that the genetic mechanism(s) of carcinogenesis differs between the differentiated type and the undifferentiated type of gastric cancer and that K-ras mutations may be involved in the early stages of gastric carcinogenesis of the differentiated type.
authors.affiliation: First Department of Internal Medicine, Hiroshima University School of Medicine, Hiroshima, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Hiyama
authors.forename: Ken
authors.initials: K
authors.lastname: Haruma
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kitadai
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Masuda
authors.forename: Masaki
authors.initials: M
authors.lastname: Miyamoto
authors.forename: Shinji
authors.initials: S
authors.lastname: Tanaka
authors.forename: Masaharu
authors.initials: M
authors.lastname: Yoshihara
authors.forename: Fumio
authors.initials: F
authors.lastname: Shimamoto
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Chayama
mesh_terms: D001706:Biopsy; D002454:Cell Differentiation / Q000235:genetics; D002908:Chronic Disease; D004252:DNA Mutational Analysis; D005260:Female; D005753:Gastric Mucosa / Q000473:pathology; D005756:Gastritis / Q000150:complications / Q000235:genetics* / Q000382:microbiology / Q000473:pathology; D011905:Genes, ras / Q000235:genetics*; D016481:Helicobacter Infections / Q000150:complications / Q000235:genetics* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D013274:Stomach Neoplasms / Q000150:complications / Q000235:genetics* / Q000382:microbiology / Q000473:pathology