Ge Yubin, Dombkowski Alan A, LaFiura Katherine M, Tatman Dana, Yedidi Ravikiran S, Stout Mark L, Buck Steven A, Massey Gita, Becton David L, Weinstein Howard J, Ravindranath Yaddanapudi, Matherly Larry H, Taub Jeffrey W
Experimental and Clinical Therapeutics Program, Barbara Ann Karmanos Cancer Institute of Environmental Sciences, Wayne State University, Detroit, MI 48201, USA.
Blood. 2006 Feb 15;107(4):1570-81. doi: 10.1182/blood-2005-06-2219. Epub 2005 Oct 25.
Children with Down syndrome (DS) with acute megakaryocytic leukemia (AMkL) have very high survival rates compared with non-DS AMkL patients. Somatic mutations identified in the X-linked transcription factor gene, GATA1, in essentially all DS AMkL cases result in the synthesis of a shorter (40 kDa) protein (GATA1s) with altered transactivation activity and may lead to altered expression of GATA1 target genes. Using the Affymetrix U133A microarray chip, we identified 551 differentially expressed genes between DS and non-DS AMkL samples. Transcripts for the bone marrow stromal-cell antigen 2 (BST2) gene, encoding a transmembrane glycoprotein potentially involved in interactions between leukemia cells and bone marrow stromal cells, were 7.3-fold higher (validated by real-time polymerase chain reaction) in the non-DS compared with the DS group. Additional studies confirmed GATA1 protein binding and transactivation of the BST2 promoter; however, stimulation of BST2 promoter activity by GATA1s was substantially reduced compared with the full-length GATA1. CMK sublines, transfected with the BST2 cDNA and incubated with HS-5 bone marrow stromal cells, exhibited up to 1.7-fold reduced cytosine arabinoside (ara-C)-induced apoptosis, compared with mock-transfected cells. Our results demonstrate that genes that account for differences in survival between DS and non-DS AMkL cases may be identified by microarray analysis and that differential gene expression may reflect relative transactivation capacities of the GATA1s and full-length GATA1 proteins.
与非唐氏综合征（DS）急性巨核细胞白血病（AMkL）患者相比，患有DS且患AMkL的儿童生存率非常高。在基本上所有DS AMkL病例中，X连锁转录因子基因GATA1中鉴定出的体细胞突变导致合成一种较短（40 kDa）的蛋白质（GATA1s），其反式激活活性发生改变，并可能导致GATA1靶基因的表达改变。使用Affymetrix U133A微阵列芯片，我们鉴定出DS和非DS AMkL样本之间有551个差异表达基因。骨髓基质细胞抗原2（BST2）基因的转录本编码一种可能参与白血病细胞与骨髓基质细胞相互作用的跨膜糖蛋白，在非DS组中比DS组高7.3倍（通过实时聚合酶链反应验证）。进一步的研究证实了GATA1蛋白与BST2启动子的结合及反式激活；然而，与全长GATA1相比，GATA1s对BST2启动子活性的刺激显著降低。用BST2 cDNA转染并与HS-5骨髓基质细胞孵育的CMK亚系，与mock转染细胞相比，阿糖胞苷（ara-C）诱导的细胞凋亡最多降低了1.7倍。我们的结果表明，通过微阵列分析可以鉴定出导致DS和非DS AMkL病例生存差异的基因，并且差异基因表达可能反映了GATA1s和全长GATA1蛋白的相对反式激活能力。
