Mutational analysis of the 5' noncoding region of the bcl-6 gene in primary gastric lymphomas.
Bcl-6 mRNA and protein are frequently expressed in the transformed counterparts of the germinal center B-cells, diffuse large B-cell lymphoma and follicular lymphoma, irrespective of the gene rearrangements. Most of the primary gastric lymphomas are thought to be of mucosa-associated lymphoid tissue (MALT) origin, and neither bcl-6 gene rearrangement nor protein expression is found in low-grade gastric lymphomas of the MALT type as in normal marginal zone cells. However, bcl-6 protein expression was identified in high-grade gastric lymphomas, suggesting its role in high-grade transformation. In this study, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis for bcl-6 primer was performed in order to ascertain the molecular mechanisms of bcl-6 protein expression in primary gastric lymphomas. A total 31 cases of gastric lymphoma were classified into low-grade gastric lymphomas of MALT type (n = 13), high-grade gastric lymphomas of MALT type (n = 6) and gastric diffuse large B-cell lymphomas (n = 12). Bcl-6 mutations were observed in 11 of 13 (84.6%) low-grade gastric lymphomas of the MALT type and in 8 of 12 (66.7%) diffuse large B-cell gastric lymphomas. In 6 cases of the high-grade gastric lymphomas of the MALT type, both the low- and high-grade components demonstrated the same frequency (3/6, 50%) of mutations. The tissue obtained from the marginal zone of Peyer's patch by microdissection technique revealed no bcl-6 mutations by the PCR-SSCP analysis. These findings suggest that the acquisition process of bcl-6 mutations by the marginal zone cells may be involved in the lymphomagenesis of the stomach, but our data does not explain the reason why bcl-6 protein is expressed only in high-grade gastric lymphomas.
Go
J H
JH
Department of Pathology, Dankook University College of Medicine, Cheonan, Chungnam, Korea. jaihyang@yahoo.co.kr
Yang
W I
WI
Ree
H J
HJ
D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000032:analysis; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics*; D004210:Dissection; D006801:Humans; D018442:Lymphoma, B-Cell, Marginal Zone / Q000737:chemistry / Q000235:genetics* / Q000473:pathology; D016403:Lymphoma, Large B-Cell, Diffuse / Q000737:chemistry / Q000235:genetics* / Q000473:pathology; D008846:Micromanipulation; D009154:Mutation; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000235:genetics*; D051560:Proto-Oncogene Proteins c-bcl-6; D013274:Stomach Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000473:pathology; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics*
D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; D051560:Proto-Oncogene Proteins c-bcl-6; D014157:Transcription Factors