E-cadherin expression is silenced by 5' CpG island methylation in acute leukemia.
E-cadherin expression is silenced by 5' CpG island methylation in acute leukemia.
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发表时间：
2000-11
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通讯作者：
P. Corn;B. Smith;Emily S. Ruckdeschel;Donna B. Douglas;S. Baylin;J. Herman
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作者：
P. Corn;B. Smith;Emily S. Ruckdeschel;Donna B. Douglas;S. Baylin;J. Herman
E-钙粘附素是一种跨膜糖蛋白，可介导正常上皮细胞间钙离子依赖的细胞间黏附。在上皮性肿瘤中，E-钙粘附素的表达经常减少，这一事件有助于肿瘤的侵袭和转移。E-钙粘附素在造血组织中的作用尚不清楚。在正常骨髓中，E-钙粘附素在红系祖细胞、CD34+干细胞和基质细胞上表达，在造血过程中可能参与细胞间的相互作用。在这项研究中，我们使用套式聚合酶链式反应的方法，检测E-钙粘蛋白5‘CpG岛在正常供者的血液和骨髓样本以及急性白血病患者的骨髓中的甲基化状态。在正常外周血单核细胞和骨髓中，E-钙粘附素完全没有甲基化。在外周血单核细胞中，逆转录-聚合酶链式反应(RT-PCR)检测到明显的表达。免疫印迹证实E-钙粘素蛋白在两个来自正常供者的淋巴母细胞系中表达。相反，在4个白血病细胞系中有4个(100%)、44个急性髓系白血病中有14个(32%)和33个急性淋巴细胞白血病中有18个(53%)E-钙粘附素异常甲基化。对原发白血病的基因组亚硫酸氢盐测序证实了CpG岛上密集的甲基化。在白血病细胞系和原发白血病中，甲基化与E-钙粘蛋白RNA和蛋白的丢失有关。经5-氮杂-2‘-脱氧胞苷处理后，甲基化的白血病细胞株同时表达E-钙粘蛋白转录本和蛋白。我们的结果表明，E-钙粘素甲基化在急性白血病中普遍存在，并提出了E-钙粘附素在白血病发生中下调的假说。
E-Cadherin is a transmembrane glycoprotein that mediates Ca2+-dependent intercellular adhesion in normal epithelium. In tumors of epithelial origin, E-cadherin expression frequently is reduced, an event that contributes to tumor invasion and metastasis. The role of E-cadherin in hematopoietic tissues is less clear. In normal bone marrow, E-cadherin is expressed on erythroid progenitors, CD34+ stem cells, and stromal cells, where it likely contributes to intercellular interactions during hematopoiesis. In this study, we used a nested-PCR approach to examine the methylation status of the E-cadherin 5' CpG island in blood and bone marrow samples from normal donors and in bone marrow from patients with acute leukemia. In normal peripheral blood mononuclear cells and bone marrow, E-cadherin was completely unmethylated. In peripheral blood mononuclear cells, expression was evident by reverse transcription-PCR. Immunoblotting confirmed E-cadherin protein expression in two lymphoblastoid cell lines derived from normal donors. In contrast, E-cadherin was aberrantly methylated in 4 of 4 (100%) leukemia cell lines, 14 of 44 (32%) acute myelogenous leukemias, and 18 of 33 (53%) acute lymphoblastic leukemias. Genomic bisulfite sequencing of primary leukemias confirmed dense methylation across the CpG island. Methylation was associated with loss of E-cadherin RNA and protein in leukemia cell lines and primary leukemias. Following treatment with 5-aza-2'-deoxycytidine, a methylated leukemia cell line expressed both E-cadherin transcript and protein. Our results show that methylation of E-cadherin occurs commonly in acute leukemia and suggests a hypothesis for E-cadherin down-regulation in leukemogenesis.