The antiapoptotic protein, FLIP, is regulated by heterogeneous nuclear ribonucleoprotein K and correlates with poor overall survival of nasopharyngeal carcinoma patients
The antiapoptotic protein, FLIP, is regulated by heterogeneous nuclear ribonucleoprotein K and correlates with poor overall survival of nasopharyngeal carcinoma patients
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DOI：
10.1038/cdd.2010.24
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发表时间：
2010-09-01
影响因子：
12.4
通讯作者：
Chang, Y-S
中科院分区：
文献类型：
--
作者：
Chen, L-C;Chung, I-C;Chang, Y-S
异质核核糖核蛋白K（hnRNP K）介导的抗凋亡活性的一部分，诱导下游抗凋亡基因。为了系统地鉴定鼻咽癌（NPC）中hnRNP K的靶基因，利用亲和层析芯片鉴定了在原发性NPC中过表达的基因和在NPC-TW 02细胞中被hnRNP K敲低下调的基因。所得到的基因集包括抗凋亡基因FLIP，其被选择用于进一步研究。在用hnRNP K siRNA处理的细胞中，TRAIL诱导的凋亡增强，FLIP蛋白水平降低。启动子，DNA下拉和染色质免疫沉淀分析表明，hnRNP K直接与FLIP启动子上的poly（C）元件相互作用，导致转录激活。通过iTRAQ-质谱鉴定与poly（C）元件或其突变体差异相关的蛋白质，核仁素被确定为FLIP激活的hnRNP K的辅因子。此外，FLIP在肿瘤细胞中高表达，并且这种高水平表达与高水平hnRNP K表达（P=0.002）和低总生存率（P=0.015）显著相关。多因素分析证实FLIP是影响鼻咽癌预后的独立因素。总之，这些发现表明FLIP的表达受hnRNP K和核仁素的转录调控，并可能是一个潜在的预后和治疗NPC的标志物。Cell Death and Differentiation（2010）17，1463-1473; doi：10.1038/cdd.2010.24; 2010年3月12日在线发表
Heterogeneous nuclear ribonucleoprotein K (hnRNP K) mediates antiapoptotic activity in part by inducing downstream antiapoptotic genes. To systematically identify hnRNP K targets in nasopharyngeal carcinoma (NPC), affymetrix chips were used to identify genes that were both overexpressed in primary NPC and downregulated by hnRNP K knockdown in NPC-TW02 cells. The resulting gene set included the antiapoptotic gene, FLIP, which was selected for further study. In cells treated with hnRNP K siRNA, TRAIL-induced apoptosis was enhanced and the FLIP protein level was reduced. Promoter, DNA pull-down and chromatin-immunoprecipitation assays revealed that hnRNP K directly interacts with the poly(C) element on the FLIP promoter, resulting in transcriptional activation. Through iTRAQ-mass spectrometric identification of proteins differentially associated with the poly(C) element or its mutant, nucleolin was determined to be a cofactor of hnRNP K for FLIP activation. Furthermore, FLIP was highly expressed in tumor cells, and this high-level expression was significantly correlated with high-level hnRNP K expression (P=0.002) and poor overall survival (P=0.015) as examined in 67 NPC tissues. A multivariate analysis confirmed that FLIP was an independent prognostic factor for NPC. Taken together, these findings indicate that FLIP expression is transcriptionally regulated by hnRNP K and nucleolin, and may be a potential prognostic and therapeutic marker for NPC. Cell Death and Differentiation (2010) 17, 1463-1473; doi:10.1038/cdd.2010.24; published online 12 March 2010