Simpson Lesley A, Burwell Emily A, Thompson Kida A, Shahnaz Samira, Chen Allen R, Loeb David M
Division of Pediatric Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD 21231, USA.
Blood. 2006 Jun 15;107(12):4695-702. doi: 10.1182/blood-2005-10-4025. Epub 2006 Feb 16.
Previous work has demonstrated that WT1 (-Ex5/-KTS) potentiates granulocyte colony-stimulating factor (G-CSF)-mediated granulocytic differentiation. This WT1 isoform suppresses cyclin E, which may contribute to the prodifferentiation effect by slowing proliferation, but WT1 target genes that affect survival might also be involved. We screened a cDNA array and identified the bCL2 family member A1/BFL1 as a new WT1 target gene in 32D cl3 murine myeloblast cells. Induction of WT1 (-Ex5/-KTS) expression is accompanied by up-regulation of A1 on the cDNA array, and this up-regulation was confirmed by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Moreover, both promoter-reporter assays and chromatin immunoprecipitation assays suggest that this isoform of WT1 activates the promoter directly. Constitutive expression of A1 in 32D cl3 cells induces spontaneous granulocytic differentiation, with both morphologic and cell-surface antigen changes, as well as resistance both to chemotherapy and to withdrawal of interleukin-3 (IL-3). Finally, we note an association between WT1 expression and A1 expression in primary acute myeloid leukemia samples. Taken together, these results demonstrate that A1 is a new WT1 target gene involved in both granulocytic differentiation and resistance to cell death, and suggests that these genes might play an important role in the biology of high-risk leukemias.
先前的研究表明，WT1（-Ex5/-KTS）可增强粒细胞集落刺激因子（G-CSF）介导的粒细胞分化。这种WT1异构体可抑制细胞周期蛋白E，这可能通过减缓增殖而有助于促分化作用，但影响存活的WT1靶基因可能也参与其中。我们筛选了一个cDNA阵列，并在32D cl3小鼠成髓细胞中鉴定出bCL2家族成员A1/BFL1是一个新的WT1靶基因。WT1（-Ex5/-KTS）表达的诱导伴随着cDNA阵列上A1的上调，并且这种上调通过半定量逆转录-聚合酶链反应（RT-PCR）得到证实。此外，启动子报告基因检测和染色质免疫沉淀检测均表明，这种WT1异构体直接激活启动子。32D cl3细胞中A1的组成型表达诱导自发粒细胞分化，伴有形态学和细胞表面抗原变化，以及对化疗和白细胞介素-3（IL-3）撤除的抗性。最后，我们注意到原发性急性髓细胞白血病样本中WT1表达与A1表达之间存在关联。综上所述，这些结果表明A1是一个新的WT1靶基因，参与粒细胞分化和对细胞死亡的抗性，并提示这些基因可能在高危白血病的生物学特性中发挥重要作用。
