Crainie M, Belch A R, Mant M J, Pilarski L M
Departments of Oncology and Medicine, University of Alberta and the Cross Cancer Institute, Edmonton, Canada.
Blood. 1999 Mar 1;93(5):1684-96.
The receptor for hyaluronan (HA)-mediated motility (RHAMM) controls motility by malignant cells in myeloma and is abnormally expressed on the surface of most malignant B and plasma cells in blood or bone marrow (BM) of patients with multiple myeloma (MM). RHAMM cDNA was cloned and sequenced from the malignant B and plasma cells comprising the myeloma B lineage hierarchy. Three distinct RHAMM gene products, RHAMMFL, RHAMM-48, and RHAMM-147, were cloned from MM B and plasma cells. RHAMMFL was 99% homologous to the published sequence of RHAMM. RHAMM-48 and RHAMM-147 variants align with RHAMMFL, but are characterized by sequence deletions of 48 bp (16 amino acids [aa]) and 147 bp (49 aa), respectively. The relative frequency of these RHAMM transcripts in MM plasma cells was determined by cloning of reverse-transcriptase polymerase chain reaction (RT-PCR) products amplified from MM plasma cells. Of 115 randomly picked clones, 49% were RHAMMFL, 47% were RHAMM-48, and 4% were RHAMM-147. All of the detected RHAMM variants contain exon 4, which is alternatively spliced in murine RHAMM, and had only a single copy of the exon 8 repeat sequence detected in murine RHAMM. RT-PCR analysis of sorted blood or BM cells from 22 MM patients showed that overexpression of RHAMM variants is characteristic of MM B cells and BM plasma cells in all patients tested. RHAMM also appeared to be overexpressed in B lymphoma and B-chronic lymphocytic leukemia (CLL) cells. In B cells from normal donors, RHAMMFL was only weakly detectable in resting B cells from five of eight normal donors or in chronically activated B cells from three patients with Crohn's disease. RHAMM-48 was detectable in B cells from one of eight normal donors, but was undetectable in B cells of three donors with Crohn's disease. RHAMM-147 was undetectable in normal and Crohn's disease B cells. In situ RT-PCR was used to determine the number of individual cells with aggregate RHAMM transcripts. For six patients, 29% of BM plasma cells and 12% of MM B cells had detectable RHAMM transcripts, while for five normal donors, only 1. 2% of B cells expressed RHAMM transcripts. This work suggests that RHAMMFL, RHAMM-48, and RHAMM-147 splice variants are overexpressed in MM and other B lymphocyte malignancies relative to resting or in vivo-activated B cells, raising the possibility that RHAMM and its variants may contribute to the malignant process in B-cell malignancies such as lymphoma, CLL, and MM.
透明质酸（HA）介导的运动受体（RHAMM）可控制骨髓瘤中恶性细胞的运动，且在多发性骨髓瘤（MM）患者血液或骨髓（BM）中的大多数恶性B细胞和浆细胞表面异常表达。从构成骨髓瘤B细胞谱系层次的恶性B细胞和浆细胞中克隆并测序了RHAMM cDNA。从MM B细胞和浆细胞中克隆出三种不同的RHAMM基因产物，即RHAMMFL、RHAMM - 48和RHAMM - 147。RHAMMFL与已发表的RHAMM序列有99%的同源性。RHAMM - 48和RHAMM - 147变体与RHAMMFL对齐，但分别具有48 bp（16个氨基酸[aa]）和147 bp（49 aa）的序列缺失。通过克隆从MM浆细胞扩增的逆转录酶聚合酶链反应（RT - PCR）产物，确定了这些RHAMM转录本在MM浆细胞中的相对频率。在115个随机挑选的克隆中，49%是RHAMMFL，47%是RHAMM - 48，4%是RHAMM - 147。所有检测到的RHAMM变体都包含外显子4，该外显子在小鼠RHAMM中是可变剪接的，并且在小鼠RHAMM中仅检测到外显子8重复序列的单拷贝。对22例MM患者分选的血液或BM细胞进行RT - PCR分析表明，RHAMM变体的过表达是所有测试患者中MM B细胞和BM浆细胞的特征。RHAMM在B淋巴瘤和B细胞慢性淋巴细胞白血病（CLL）细胞中似乎也过表达。在正常供体的B细胞中，仅在8名正常供体中5人的静息B细胞或3名克罗恩病患者的慢性活化B细胞中可微弱检测到RHAMMFL。在8名正常供体中的1人的B细胞中可检测到RHAMM - 48，但在3名克罗恩病供体的B细胞中未检测到。在正常和克罗恩病B细胞中未检测到RHAMM - 147。原位RT - PCR用于确定具有聚集RHAMM转录本的单个细胞数量。对于6例患者，29%的BM浆细胞和12%的MM B细胞具有可检测到的RHAMM转录本，而对于5名正常供体，仅1.2%的B细胞表达RHAMM转录本。这项工作表明，相对于静息或体内活化的B细胞，RHAMMFL、RHAMM - 48和RHAMM - 147剪接变体在MM和其他B淋巴细胞恶性肿瘤中过表达，这增加了RHAMM及其变体可能促成淋巴瘤、CLL和MM等B细胞恶性肿瘤中恶性过程的可能性。
