Rhom-2 expression does not always correlate with abnormalities on chromosome 11 at band p13 in T-cell acute lymphoblastic leukemia
Rhom-2 expression does not always correlate with abnormalities on chromosome 11 at band p13 in T-cell acute lymphoblastic leukemia
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T 细胞急性淋巴细胞白血病中 Rhom-2 表达并不总是与 11 号染色体 p13 区异常相关
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发表时间：
1992
期刊：
影响因子：
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通讯作者：
R. Goorha
中科院分区：
文献类型：
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作者：
T. Fitzgerald;G. Neale;S. Raimondi;R. Goorha
在T细胞急性淋巴细胞白血病（T-ALL）中非随机重组的常见位点是11号染色体p13。（7;11）（q35;p13）易位的分子特征表明，易位断裂点位于T-ALLbcr位点5′端2 kb处，导致T细胞受体（TCR）β基因与rhom-2基因位点并置。北方印迹分析未检测到rhom-2基因在（7;11）易位的白血病原始细胞中的表达。然而，使用敏感的基于聚合酶链反应（PCR）的测定，（7;11）易位显示rhom-2的痕量表达，其水平为0.01%TCR-β信使。因为rhom-2被认为是原癌基因，所以通过使用PCR测定比较7个另外的T-ALL、正常胸腺细胞以及CEM（前T）和HPB（成熟T）细胞系中rhom-2表达水平来研究rhom-2在（7;11）易位中痕量表达的意义。CEM细胞、正常胸腺细胞和1例原始细胞无11号染色体细胞遗传学异常的患者不表达rhom-2，表明rhom-2在T细胞中不正常表达。其他6个T-ALL分为三类：（1）2个T-ALL在易位存在时过表达rhom-2;（2）2个T-ALL在易位存在时有痕量表达;（3）2个T-ALL在11号染色体p13处有痕量表达，没有观察到异常。因此，数据表明，并非所有的易位在T-ALLbcr基因座的结果在过度表达rhom-2。为了解释在这些T-ALL中看到的rhom-2表达的鲜明对比，提出了一个模型，该模型在T-ALLbcr基因座中具有负调控元件，该元件在某些情况下被破坏，导致rhom-2的过表达。
A frequent site for nonrandom recombination in T-cell acute lymphoblastic leukemia (T-ALL) is chromosome 11 at p13. The molecular characterization of a (7;11)(q35;p13) translocation showed that the translocation breakpoint was 2 kb 5′ to the T-ALLbcr locus resulting in the juxtaposition of the T-cell receptor (TCR) beta gene to the rhom-2 gene locus. Northern blot analysis did not detect expression of the rhom-2 gene in the leukemic blasts of the (7;11) translocation. However, using a sensitive polymerase chain reaction (PCR)-based assay, the (7;11) translocation showed a trace expression of rhom-2 at a level of 0.01% of TCR-beta message. Because rhom-2 is considered a proto- oncogene, the significance of the trace expression of rhom-2 in the (7;11) translocation was investigated by comparing the level of rhom-2 expression in 7 additional T-ALLs, normal thymocytes, and CEM (pre-T) and HPB (mature-T) cell lines using the PCR assay. The CEM cells, normal thymocytes, and one patient, whose blasts had no cytogenetic abnormality of chromosome 11, did not express rhom-2 indicating that rhom-2 is not normally expressed in T cells. The other six T-ALLs fell into three categories: (1) two T-ALLs overexpressed rhom-2 in the presence of a translocation; (2) two T-ALLs had trace expression in the presence of a translocation; and (3) two T-ALLs had trace expression with no observable abnormalities on chromosome 11 at p13. Therefore, the data indicate that not all translocations at the T-ALLbcr locus result in overexpression of rhom-2. To account for the sharp contrast in rhom-2 expression seen in these T-ALLs, a model is proposed with a negative regulatory element in the T-ALLbcr locus that is disrupted in some of the cases leading to overexpression of rhom-2.
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影响因子：
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