Higher methylation intensity induced by EBV LMP1 via NF-κB/DNMT3b signaling contributes to silencing of PTEN gene.
Higher methylation intensity induced by EBV LMP1 via NF-κB/DNMT3b signaling contributes to silencing of PTEN gene.
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EBV LMP1 通过 NF-kappa B/DNMT3b 信号传导诱导的较高甲基化强度有助于 PTEN 基因的沉默
DOI：
10.18632/oncotarget.9474
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发表时间：
2016-06-28
期刊：
影响因子：
--
通讯作者：
Li X
中科院分区：
文献类型：
--
作者：
Peng H;Chen Y;Gong P;Cai L;Lyu X;Jiang Q;Wang J;Lu J;Yao K;Liu K;Li J;Li X
磷酸酶和张力蛋白同源物(PTEN)是一种主要的肿瘤抑制基因，通常通过缺失、插入和突变而沉默。我们之前发现它是通过异常的CpG岛甲基化而失活的。在这里，我们提供了进一步的证据，EBV潜伏膜蛋白1(LMP1)可以在PTEN CpG岛上诱导更高强度的DNA甲基化，在细胞和分子水平上灭活PTEN。最初，在EBV感染的鼻咽癌(NPC)细胞中观察到PTEN CpG岛的甲基化强度增加，伴随着PTEN表达的降低。在PTEN启动子甲基化的鼻咽癌组织中，LMP1在高甲基化强度组较低甲基化强度组高表达，DNA甲基转移酶3b(Dnmt3b)的表达与LMP1的表达呈正相关。此外，将LMP1基因导入EBV阴性的鼻咽癌细胞，发现LMP1上调了Dnmt3b的表达，导致PTEN CpG岛甲基化强度增加。从机制上讲，计算预测和荧光素酶报告实验发现在Dnmt3b启动子上有一个功能性的NF-κB结合位点，突变的NF-κB结合位点使LMP1介导的Dnmt3b激活失效。染色质免疫沉淀显示，NF-κB p65亚基与Dnmt3b启动子组成性结合，支持EB病毒LMP1通过NF-κB信号激活Dnmt3b。此外，在表达LMP1的鼻咽癌细胞中，Dnmt3b的表达水平增加，而NF-κB抑制剂PDTC可拮抗LMP1介导的Dnmt3b的过度表达。因此，本研究首次报道了LMP1介导的NF-κB可以上调DNMT3B的转录，从而导致PTEN CpG岛上相对较高的甲基化强度，最终使主要的肿瘤抑制基因PTEN沉默。
Phosphatase and tensin homolog (PTEN) is a major tumor suppressor and usually silenced via the deletion, insertion and mutation. We previously discovered its inactivation via aberrant CpG island methylation. Here, we provide further evidence that EBV latent membrane protein 1(LMP1) can induce a higher intensity of DNA methylation at PTEN CpG islands, inactivating PTEN at the cellular and molecular level. Initially, increased methylation intensity of PTEN CpG islands was observed in EBV-infected nasopharyngeal carcinoma (NPC) cells, accompanied by decreased PTEN expression. In NPC tissue samples showing the methylation at PTEN promoter, LMP1 was highly expressed in higher methylation intensity group relative to lower intensity group, and DNA methyltransferase 3b (DNMT3b) expression was positively correlated with LMP1 expression. Moreover, transfection of LMP1 gene into EBV-negative NPC cells demonstrated that LMP1 up-regulated DNMT3b expression, leading to a higher intensity of PTEN CpG island methylation. Mechanistically, computational prediction and luciferase reporter assay identified a functional NF-κB binding site on DNMT3b promoter and the mutated NF-κB binding site abolished LMP1-mediated DNMT3b activation. Chromatin immunoprecipitation displayed that NF-κB p65 subunit constitutively bound to DNMT3b promoter, supporting the activation of DNMT3b by EBV LMP1 via NF-κB signaling. Furthermore, the expression level of DNMT3b was observed to be increased in the nuclei of LMP1-expressing NPC cells, and a NF-κB inhibitor, PDTC, counteracted LMP1-mediated DNMT3b overexpression. Thus, this study first reports that LMP1-mediated NF-κB can up-regulate DNMT3b transcription, thereby leading to relatively higher methylation intensity at PTEN CpG islands, and ultimately silencing major tumor suppressor PTEN.
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影响因子：
15.9
作者：
Paschos K;Allday MJ
通讯作者：
Allday MJ
DOI：
10.3390/v6104047
发表时间：
2014-10-23
期刊：
Viruses
影响因子：
--
作者：
Morales-Sánchez A;Fuentes-Pananá EM
通讯作者：
Fuentes-Pananá EM
影响因子：
2.4
作者：
Fendri, Ali;Khabir, Abdelmajid;Mokdad-Gargouri, Raja
通讯作者：
Mokdad-Gargouri, Raja
影响因子：
64.5
作者：
Okano, M;Bell, DW;Li, E
通讯作者：
Li, E
影响因子：
15.9
作者：
Baldwin, AS
通讯作者：
Baldwin, AS