Krug Utz, Yasmeen Amber, Beger Carmela, Bäumer Nicole, Dugas Martin, Berdel Wolfgang E, Müller-Tidow Carsten
Department of Medicine, Hematology and Oncology, University Hospital of Münster, 48129 Münster, Germany.
Int J Oncol. 2009 Jan;34(1):129-36.
Cyclin A1 is a cell cycle protein that is expressed in testes, brain and CD34-positive hematopoietic progenitor cells. Cyclin A1 is overexpressed in a variety of myeloid leukemic cell lines and in myeloid leukemic blasts. Transgenic cyclin A1 overexpressing mice develop acute myeloid leukemia with low frequency. In this study, we looked for putative target genes of cyclin A1 in hematopoietic cells. Microarray analysis of U937 myeloid cells overexpressing cyclin A1 versus conrol cells detected 35 differential expressed genes, 21 induced and 14 repressed ones upon cyclin A1 overexpression. Among the differentially expressed genes WT1 was chosen for further analysis. Repression of WT1 expression was confirmed on the mRNA and protein level. In addition, WT1 expression was higher in bone marrow, liver and ovary of cyclin A1-/- mice. Isoform analysis showed a profound change of the WT1 isoform ratio in U937 cyclin A1-overexpressing versus control cells. Functional analysis revealed an inhibition of colony growth when WT1 isoforms were transfected into U937 cells, which was not affected by the overexpression of cyclin A1. In addition, overexpression of the WT1-/+ isoform induced a G1 cell cycle arrest which was abrogated upon cotransfection with cyclin A1. This study identified WT1 as a repressed target of cyclin A1 and suggests that the suppression of WT1 in cyclin A1-overexpressing leukemias might play a role in the growth and suppression of apoptosis in these leukemic cells.
细胞周期蛋白A1是一种在睾丸、脑和CD34阳性造血祖细胞中表达的细胞周期蛋白。细胞周期蛋白A1在多种髓系白血病细胞系和髓系白血病原始细胞中过表达。过表达细胞周期蛋白A1的转基因小鼠低频发生急性髓系白血病。在本研究中，我们在造血细胞中寻找细胞周期蛋白A1的潜在靶基因。对过表达细胞周期蛋白A1的U937髓系细胞与对照细胞进行微阵列分析，检测到35个差异表达基因，其中21个在细胞周期蛋白A1过表达时被诱导，14个被抑制。在差异表达基因中选择WT1进行进一步分析。WT1表达的抑制在mRNA和蛋白水平得到证实。此外，在细胞周期蛋白A1基因敲除小鼠的骨髓、肝脏和卵巢中WT1表达更高。异构体分析显示，过表达细胞周期蛋白A1的U937细胞与对照细胞相比，WT1异构体比例发生了显著变化。功能分析显示，将WT1异构体转染到U937细胞中会抑制集落生长，而这不受细胞周期蛋白A1过表达的影响。此外，WT1-/+异构体的过表达诱导G1期细胞周期停滞，而与细胞周期蛋白A1共转染后这种停滞被消除。本研究确定WT1是细胞周期蛋白A1的一个被抑制的靶标，并表明在过表达细胞周期蛋白A1的白血病中WT1的抑制可能在这些白血病细胞的生长和凋亡抑制中起作用。
