EWS-FLI1 suppresses NOTCH-activated p53 in Ewing's sarcoma.
EWS-FLI1 suppresses NOTCH-activated p53 in Ewing's sarcoma.
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DOI：
10.1158/0008-5472.can-07-6145
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发表时间：
2008-09-01
期刊：
影响因子：
11.2
通讯作者：
Kovar H
中科院分区：
文献类型：
--
作者：
Ban J;Bennani-Baiti IM;Kauer M;Schaefer KL;Poremba C;Jug G;Schwentner R;Smrzka O;Muehlbacher K;Aryee DN;Kovar H
虽然p53是癌症中最常见的突变基因，但有一半的人类肿瘤保留了野生型p53，因此尚不清楚正常的p53功能是否受到其他癌症相关改变的影响。一个例子是尤文氏肉瘤家族肿瘤（ESFT），其中90%表达野生型p53。ESFT的特征是EWS-FLI 1癌基因融合。研究6个ESFT细胞系，在野生型p53背景下沉默EWS-FLI 1导致p53和p21 WAF 1/CIP 1水平增加，引起细胞周期停滞。使用候选基因方法，HEY 1与p53诱导相关。HEY 1在59个原发性肿瘤中很少表达，但在ESFT细胞系中EWS-FLI 1敲低后始终诱导表达。NOTCH信号通路靶向HEY 1，我们显示NOTCH 2和NOTCH 3在ESFT原发性肿瘤和细胞系中表达。在EWS-FLI 1沉默，NOTCH 3加工伴随着核转位的激活的胞内结构域中观察到的所有，但一个p53突变细胞系。在具有最高HEY 1诱导的细胞系中，NOTCH 3激活是JAG 1转录诱导的结果。通过特异性siRNA调节JAG 1、通过GSI或异位NUMB 1抑制NOTCH加工以及siRNA介导的HEY 1敲低均抑制p53和p21 WAF 1/CIP 1诱导。相反，JAG 1、激活的NOTCH 3或HEY 1的强制表达会诱导p53和p21 WAF 1/CIP 1。这些结果表明，EWS-FLI 1的抑制重新激活ESFT细胞中的NOTCH信号传导，导致p53依赖性细胞周期停滞。我们的数据将EWS-FLI 1与NOTCH和p53通路联系起来，并为NOTCH肿瘤抑制作用和保留野生型p53的癌症的肿瘤发生提供了合理的基础。
Although p53 is the most frequently mutated gene in cancer, half of human tumors retain wild-type p53, whereby it is unknown whether normal p53 function is compromised by other cancer-associated alterations. One example is Ewing’s sarcoma family tumors (ESFT), where 90% express wild-type p53. ESFT are characterized by EWS-FLI1 oncogene fusions. Studying 6 ESFT cell lines, silencing of EWS-FLI1 in a wild-type p53 context resulted in increased p53 and p21WAF1/CIP1 levels, causing cell cycle arrest. Using a candidate gene approach, HEY1 was linked to p53 induction. HEY1 was rarely expressed in 59 primary tumors, but consistently induced upon EWS-FLI1 knockdown in ESFT cell lines. The NOTCH signaling pathway targets HEY1, and we show NOTCH2 and NOTCH3 to be expressed in ESFT primary tumors and cell lines. Upon EWS-FLI1 silencing, NOTCH3 processing accompanied by nuclear translocation of the activated intracellular domain was observed in all but one p53-mutant cell line. In cell lines with the highest HEY1 induction, NOTCH3 activation was the consequence of JAG1 transcriptional induction. JAG1 modulation by specific siRNA, NOTCH-processing inhibition by either GSI or ectopic NUMB1, and siRNA-mediated HEY1 knockdown all inhibited p53 and p21WAF1/CIP1 induction. Conversely, forced expression of JAG1, activated NOTCH3, or HEY1 induced p53 and p21WAF1/CIP1. These results indicate that suppression of EWS-FLI1 reactivates NOTCH signaling in ESFT cells, resulting in p53-dependent cell cycle arrest. Our data link EWS-FLI1 to the NOTCH and p53 pathways and provide a plausible basis both for NOTCH tumor suppressor effects and oncogenesis of cancers that retain wild-type p53.