The Ews/Fli-1 fusion gene changes the status of p53 in neuroblastoma tumor cell lines.
The Ews/Fli-1 fusion gene changes the status of p53 in neuroblastoma tumor cell lines.
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Ews/Fli-1 融合基因改变神经母细胞瘤细胞系中 p53 的状态。
DOI：
10.1158/0008-5472.can-04-1610
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发表时间：
2004
期刊：
影响因子：
11.2
通讯作者：
Weissman,BernardE
中科院分区：
文献类型：
--
作者：
Rorie,ChecoJ;Weissman,BernardE
尤文肉瘤/外周神经外胚层肿瘤的一个标志是Ews/Fli-1嵌合癌基因的存在。有趣的是，用Ews/Fli-1感染神经母细胞瘤肿瘤细胞系将神经母细胞瘤的分化程序转换为尤文肉瘤/外周神经外胚层肿瘤。在这里，我们研究了Ews/Fli-1稳定表达后，神经母细胞瘤中胞质隔离的wt-p53的状态。免疫荧光显示，在神经母细胞瘤Ews/Fli-1感染细胞系，p53从点状模式的细胞质隔离增加核定位。Western blot分析显示，PARC在一个神经母细胞瘤细胞系中下调，但在第二个细胞系中不表达。因此，降低PARC表达不能完全解释缓解神经母细胞瘤肿瘤细胞中的p53隔离。神经母细胞瘤-Ews/Fli-1感染细胞系显示p53蛋白表达显著增加，而没有转录上调。有趣的是，p53主要被磷酸化，而没有激活其下游靶点p21 WAF 1。Western blot分析显示，当MDM 2基因表达没有改变时，MDM 2的负性蛋白调节因子p14 ARF增加。这些观察结果表明，下游p53通路可能是失活的异常p53的结果。我们还发现，p53在神经母细胞瘤-Ews/Fli-1感染物中具有延长的半衰期，尽管在神经母细胞瘤-Ews/Fli-1感染物细胞系中保留了野生型序列。然后，我们测试了p53反应途径，并观察到神经母细胞瘤亲本细胞对遗传毒性应激有反应，而神经母细胞瘤-Ews/Fli-1感染物没有。这些结果表明Ews/Fli-1可以直接阻断p53通路，从而促进肿瘤的发生。这些研究也提供了额外的洞察p53通路蛋白之间的关系。
One hallmark of Ewing’s sarcoma/peripheral neuroectodermal tumors is the presence of theEws/Fli-1chimeric oncogene. Interestingly, infection of neuroblastoma tumor cell lines with Ews/Fli-1 switches the differentiation program of neuroblastomas to Ewing’s sarcoma/peripheral neuroectodermal tumors. Here we examined the status of cytoplasmically sequesteredwt-p53 in neuroblastomas after stable expression of Ews/Fli-1. Immunofluorescence revealed that in the neuroblastoma-Ews/Fli-1 infectant cell lines, p53 went from a punctate-pattern of cytoplasmic sequestration to increased nuclear localization. Western blot analysis revealed that PARC was down-regulated in one neuroblastoma cell line but not expressed in the second. Therefore, decreased PARC expression could not fully account for relieving p53 sequestration in the neuroblastoma tumor cells. Neuroblastoma-Ews/Fli-1 infectant cell lines showed marked increases in p53 protein expression without transcriptional up-regulation. Interestingly, p53 was primarily phosphorylated, without activation of its downstream target p21WAF1. Western blot analysis revealed that whereasMDM2gene expression does not change, p14ARF, a negative protein regulator of MDM2, increases. These observations suggest that the downstream p53 pathway may be inactivated as a result of abnormal p53. We also found that p53 has an extended half-life in the neuroblastoma-Ews/Fli-1 infectants despite the retention of a wild-type sequence in neuroblastoma-Ews/Fli-1 infectant cell lines. We then tested the p53 response pathway and observed that the neuroblastoma parent cells responded to genotoxic stress, whereas the neuroblastoma-Ews/Fli-1 infectants did not. These results suggest that Ews/Fli-1 can directly abrogate the p53 pathway to promote tumorigenesis. These studies also provide additional insight into the relationship among the p53 pathway proteins.