Development and clinical application of molecular diagnosis in leukemias

白血病分子诊断技术的发展及临床应用

基本信息

批准号：
04557133
负责人：
HIRAI Hisamaru
金额：
$ 9.73万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

项目摘要

The t (3 ; 21) (q26 ; q22)translocation, which is one of consistent chromosomal abnormalities found in blastic crisis of chronic myelocytic leukemia(CML) , is thought to play an important role in leukemic progression of CML to an acute blastic crisis phase. The AML1 gene, which is located at the translocation breakpoint of the t (8 ; 21) (q22 ; q22) translocation found in acute myelocytic leukemia, was also rearranged by the t (3 ; 21) (q26 ; q22) translocation. Screening of a cDNA library of the t (3 ; 21) -carrying leukemic cell line cells (SKH1) resulted in the isolation of AML1/EVI-1 chimeric cDNAs. SKH1 cells expressed the 180 kD AML1/EVI-1 fusion protein containing an amino-terminal half of AML1 including a runt homology domain which is fused to the entire of zinc finger EVI-1 protein. These findings strogly suggest that the t (3 ; 21) translocation results in the fromation of a new class of a chimeric transcription factor which could contribute to leukemic progression of CML thr … More ough interference with cell growth and differentiation. Biochemical analyzes revealed that AML1/EVI-1 itself does not alter the transactivation level through PEBP2 sites but dominantly suppresses the transactivation by intact AML1, which is assumed to be a stimulator of myeloid cell differentiation. The DNA-binding competition is a putative mechanism of such dominant negative effects of AML1/EVI-1 because it binds to PEBP2 sites in the higher affinity than AML1.Furthermore, AML1/EVI-1 stimulated the c-fos promoter transactivation and raised the AP-1 activity. Experiments, using deletion mutants of AML1/EVI-1, showed that these two functions are mutually independent because the dominant negative effects upon intact AML1 and the stimulation of AP-1 activity are dependent on the runt domain and the zinc finger domain near the C-terminus, respectively. Furthermore we showed that AML1/EVI-1 blocks granulocytic differentiation, otherwise induced by G-CSF,of 32Dc13 myeloid cells. It was also suggested that both AML1-derived and EVI-1-derived portions of the fusion protein play crucial roles for such differentiation block. We conclude that the leukemic cell transformation in t (3 ; 21) leukemias is probably caused by those dual functions of AML1/EVI-1 chimeric protein. Less

t (3; 21) (q26; q22) 易位是慢性粒细胞白血病 (CML) 急变期中发现的一致染色体异常之一，被认为在 CML 白血病进展为急性急变期中发挥重要作用AML1 基因，位于发现的 t (8; 21) (q22; q22) 易位的易位断点处。在急性髓细胞白血病中，也通过 t (3 ; 21) (q26 ; q22) 易位进行重排。筛选携带 t (3 ; 21) 的白血病细胞系细胞 (SKH1) 的 cDNA 文库，结果分离出 t (3 ; 21) (q26 ; q22) 。 AML1/EVI-1 嵌合 cDNA SKH1 细胞表达含有 180 kD AML1/EVI-1 融合蛋白。 AML1 的氨基末端一半，包括与整个锌指 EVI-1 蛋白融合的矮同源结构域，这些发现有力地表明 t (3; 21) 易位导致了一类新的嵌合转录的形成。生化双胞胎显示，AML1/EVI-1 本身不会通过 PEBP2 位点改变反式激活水平，但可能会导致 CML 白血病进展。主要抑制完整 AML1 的反式激活，而完整 AML1 被认为是骨髓细胞分化的刺激剂，DNA 结合竞争是 AML1/EVI-1 的这种显着负面影响的假定机制，因为它以更高的亲和力与 PEBP2 位点结合。此外，AML1/EVI-1 刺激 c-fos 启动子反式激活并提高 AP-1 活性。 AML1/EVI-1 表明这两个功能是相互独立的，因为对完整 AML1 的显着负面影响和 AP-1 活性的刺激分别依赖于 C 末端附近的 runt 结构域和锌指结构域。研究表明，AML1/EVI-1 会阻断 32Dc13 骨髓细胞的粒细胞分化（否则由 G-CSF 诱导）。此外，还表明 AML1 衍生部分和 EVI-1 衍生部分均起作用。我们得出结论，t(3;21)白血病中的白血病细胞转化可能是由AML1/EVI-1嵌合蛋白的双重功能引起的。