Go J H, Yang W I, Ree H J
Department of Pathology, Dankook University College of Medicine, Cheonan, Chungnam, Korea.
Mod Pathol. 2001 May;14(5):410-4. doi: 10.1038/modpathol.3880327.
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.
Bcl-6信使核糖核酸和蛋白质经常在生发中心B细胞的转化对应物、弥漫性大B细胞淋巴瘤和滤泡性淋巴瘤中表达，与基因重排无关。大多数原发性胃淋巴瘤被认为起源于黏膜相关淋巴组织（MALT），在MALT型的低级别胃淋巴瘤中，如同正常边缘区细胞一样，未发现bcl-6基因重排和蛋白质表达。然而，在高级别胃淋巴瘤中鉴定出了bcl-6蛋白质表达，提示其在高级别转化中的作用。在本研究中，进行了针对bcl-6引物的聚合酶链反应-单链构象多态性（PCR-SSCP）分析，以确定原发性胃淋巴瘤中bcl-6蛋白质表达的分子机制。总共31例胃淋巴瘤被分为MALT型低级别胃淋巴瘤（n = 13）、MALT型高级别胃淋巴瘤（n = 6）和胃弥漫性大B细胞淋巴瘤（n = 12）。在13例MALT型低级别胃淋巴瘤中的11例（84.6%）以及12例弥漫性大B细胞胃淋巴瘤中的8例（66.7%）中观察到了bcl-6突变。在6例MALT型高级别胃淋巴瘤中，低级别和高级别成分显示出相同频率（3/6，50%）的突变。通过显微切割技术从派尔集合淋巴结边缘区获得的组织经PCR-SSCP分析未显示bcl-6突变。这些发现提示边缘区细胞获得bcl-6突变的过程可能参与了胃淋巴瘤的发生，但我们的数据无法解释为何bcl-6蛋白质仅在高级别胃淋巴瘤中表达。
