1Department of Hematology, Herlev Hospital, University of Copenhagen, Herlev, Denmark.
Haematologica. 2010 Oct;95(10):1730-7. doi: 10.3324/haematol.2010.024778. Epub 2010 May 29.
Several laboratories have shown that cells with a memory B-cell phenotype can have the same clonotype as multiple myeloma tumor cells.
The aim of this study was to determine whether some memory B cells have the same genetic alterations as their corresponding multiple myeloma malignant plasma cells. The methodology included sorting multiple myeloma or memory B cells into RNA stabilizing medium for generation of subset-specific polymerase chain reaction complementary DNA libraries from one or 100 cells.
Cells with the phenotype of tumor plasma cells (CD38(++)CD19(-)CD45(-/+)CD56(-/+/++)) or memory B cells (CD38(-)/CD19(+)/CD27(+)) were isolated by flow activated cell sorting. In samples from all four patients with multiple myeloma and from two of the three with monoclonal gammopathy of undetermined significance, we identified memory B cells expressing multiple myeloma-specific oncogenes (FGFR3; IGH-MMSET; CCND1 high) dysregulated by an IGH translocation in the respective tumor plasma cells. By contrast, in seven patients with multiple myeloma, each of whom had tumor plasma cells with a K-RAS61 mutation, a total of 32,400 memory B cells were analyzed using a sensitive allele-specific, competitive blocker polymerase chain reaction assay, but no K-RAS mutations were identified.
The increased expression of a specific "early" oncogene of multiple myeloma (monoclonal gammopathy of undetermined significance) in some memory B cells suggests that dysregulation of the oncogene occurs in a precursor B-cell that can generate memory B cells and transformed plasma cells. However, if memory B cells lack "late" oncogene (K-RAS) mutations but express the "early" oncogene, they cannot be involved in maintaining the multiple myeloma tumor, but presumably represent a clonotypic remnant that is only partially transformed.
几个实验室已经表明，具有记忆 B 细胞表型的细胞可能与多发性骨髓瘤肿瘤细胞具有相同的克隆型。
本研究的目的是确定某些记忆 B 细胞是否具有与其相应的多发性骨髓瘤恶性浆细胞相同的遗传改变。该方法包括将多发性骨髓瘤或记忆 B 细胞分类到 RNA 稳定化培养基中，以从一个或 100 个细胞中生成亚群特异性聚合酶链反应互补 DNA 文库。
通过流式细胞术激活细胞分选，分离出具有肿瘤浆细胞表型（CD38(++)CD19(-)CD45(-/+)CD56(-/+/++))或记忆 B 细胞表型（CD38(-)/CD19(+)/CD27(+))的细胞。在来自所有 4 名多发性骨髓瘤患者和 3 名单克隆丙种球蛋白病患者中的 2 名患者的样本中，我们鉴定了表达多发性骨髓瘤特异性癌基因（FGFR3；IGH-MMSET；CCND1 高）的记忆 B 细胞，这些癌基因在相应的肿瘤浆细胞中被IGH 易位失调。相比之下，在 7 名多发性骨髓瘤患者中，每个患者的肿瘤浆细胞都有 K-RAS61 突变，使用敏感的等位基因特异性竞争阻断聚合酶链反应检测分析了总共 32400 个记忆 B 细胞，但未发现 K-RAS 突变。
某些记忆 B 细胞中多发性骨髓瘤（单克隆丙种球蛋白病）的特定“早期”癌基因的过度表达表明，癌基因的失调发生在可以产生记忆 B 细胞和转化浆细胞的前 B 细胞中。然而，如果记忆 B 细胞缺乏“晚期”癌基因（K-RAS）突变但表达“早期”癌基因，则它们不能参与维持多发性骨髓瘤肿瘤，但推测代表仅部分转化的克隆型残余物。
