Sykes David B, Scheele Jurgen, Pasillas Martina, Kamps Mark P
Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0612, USA.
Leuk Lymphoma. 2003 Jul;44(7):1187-99. doi: 10.1080/1042819031000090273.
The E2a-Pbx1 oncoprotein of human pre-B cell leukemia prevents differentiation and maintains continued cell division in cultured myeloid progenitors. Previously, estrogen-dependent forms of E2a-Pbx1 were generated that immortalized neutrophil (ECoM-G cells) or monocyte (ECoM-M cells) progenitors and that permitted their terminal differentiation upon estrogen withdrawal. Here, representational difference analysis (RDA) and Affymetrix array analysis are used to identify changes in gene expression that accompany the early differentiation of these cells. The promoters of these genes, whose expression changes upon E2a-Pbx1 inactivation, integrate the biochemical mechanism through which E2a-Pbx1 arrests differentiation and maintains cell division. Inactivation of E2a-Pbx1 caused the 10- to 80-fold up regulation of a small subset of myeloid differentiation genes (MRP8, Cnlp, NB1, Bactenecin, YM1, Stefin 1, Lipocortin, Lactoferrin, gp91 phox and Ly6-G) and a 10-fold down regulation of the TLE1 corepressor gene, as well as of a group of genes expressed in dividing cells (c-Myc, Nucleophosmin, Spermidine synthase, NOP56, Hnrpa1). Transcription of 97% of cellular genes, including 300 other transcription factor genes (21 Hox genes) and other myeloid genes, varied less than 3-fold, with most varying less than 50%. Therefore, E2a-Pbx1 prevents transcription and maintains the cell cycle by a specific rather than a global transcriptional mechanism. Monocyte progenitors were distinguished by persistent expression of IRF8 and of a category of other genes characterized as "interferon-stimulated" (ISG15, ISG20, Ifit1, Ifi202a, Ifi203, IfiS204, Ifi204-related, IRF7 and Ly6-E.1), as well as by the upregulation of the Lrg21 bZip transcription factor gene during late differentiation. The synchronous expression of stage-specific and cell cycle genes regulated by E2a-Pbx1 in these cell lines comprises a model system in which analysis of their promoters can be used as a starting point to backtrack to the transcriptional mechanisms of oncogenesis by E2a-Pbx1.
人类前B细胞白血病的E2a-Pbx1癌蛋白可阻止分化，并维持培养的髓系祖细胞持续进行细胞分裂。此前，已产生了雌激素依赖型的E2a-Pbx1，它可使中性粒细胞祖细胞（ECoM-G细胞）或单核细胞祖细胞（ECoM-M细胞）永生化，并在撤除雌激素后使其终末分化。在此，运用代表性差异分析（RDA）和Affymetrix芯片分析来鉴定这些细胞早期分化过程中伴随的基因表达变化。这些基因的启动子在E2a-Pbx1失活时表达发生改变，整合了E2a-Pbx1阻止分化并维持细胞分裂的生化机制。E2a-Pbx1失活导致一小部分髓系分化基因（MRP8、Cnlp、NB1、防御素、YM1、丝抑蛋白1、脂皮质蛋白、乳铁蛋白、gp91 phox和Ly6-G）上调10至80倍，TLE1共抑制因子基因以及一组在分裂细胞中表达的基因（c-Myc、核磷蛋白、亚精胺合成酶、NOP56、Hnrpa1）下调10倍。97%的细胞基因转录，包括300个其他转录因子基因（21个Hox基因）和其他髓系基因，变化小于3倍，大多数变化小于50%。因此，E2a-Pbx1通过一种特定而非全局性的转录机制来阻止转录并维持细胞周期。单核细胞祖细胞的特征在于持续表达IRF8以及一类被归类为“干扰素刺激”的其他基因（ISG15、ISG20、Ifit1、Ifi202a、Ifi203、IfiS204、Ifi204相关基因、IRF7和Ly6-E.1），以及在晚期分化过程中Lrg21 bZip转录因子基因的上调。E2a-Pbx1在这些细胞系中对阶段特异性基因和细胞周期基因的同步表达构成了一个模型系统，在该系统中，对其启动子的分析可作为一个起点，来追溯E2a-Pbx1致癌的转录机制。
