Insufficient PINX1 expression stimulates telomerase activation by direct inhibition of EBV LMP1-NF-κB axis during nasopharyngeal carcinoma development
Insufficient PINX1 expression stimulates telomerase activation by direct inhibition of EBV LMP1-NF-κB axis during nasopharyngeal carcinoma development
复制标题
鼻咽癌发展过程中PINX1表达不足通过直接抑制EBV LMP1-NF-kappa B轴刺激端粒酶激活
DOI：
10.1016/j.bbrc.2019.04.104
复制
发表时间：
2019-06-18
影响因子：
3.1
通讯作者：
Peng，Hong
中科院分区：
文献类型：
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作者：
Liu，Yunyi;Gong，Pinggui;Peng，Hong
目的鼻咽癌（NPC）早期恶性转化与eb病毒（EBV）感染和端粒酶激活有关。EBV潜伏膜蛋白1（latent membrane protein 1, LMP1）通过触发NF-κB信号通路调控多种基因的表达。PINX1是一种通过抑制端粒酶活性和癌细胞生长而被发现的肿瘤抑制基因。然而，EBV在鼻咽癌中是否以及如何抑制PINX1表达和激活端粒酶尚不完全清楚。方法采用免疫组化、实时荧光定量PCR和Western blotting检测PINX1基因的表达。采用染色质免疫沉淀（ChIP）和双荧光素酶报告基因法研究NF-κB与PINX1之间的调控机制。采用TRAP-SYBR绿色法和Southern印迹法检测端粒酶活性和端粒长度。CCK8和EdU检测细胞增殖能力。结果首次证实PINX1在鼻咽癌中下调。在机制上，我们发现LMP1可以通过促进p65与PINX1启动子中三个特定位点的结合来抑制PINX1的转录活性，其中两个（-1698/-1689,tgcaatttcc; - 206/-197, cgggctttac）尚未报道。此外，我们还观察到LMP1过表达导致端粒酶活性增加，端粒长度延长和增殖增强。结论我们首次发现EBV通过LMP1-NF-κB-PINX1轴导致鼻咽癌端粒酶活性上调，从而导致PINX1表达降低。因此，肿瘤细胞获得了更旺盛增殖的能力。该信号通路阐明了EBV潜伏感染与端粒酶激活之间的关系，为鼻咽癌的早期诊断和治疗提供了新的思路。
ObjectiveEarly malignant transformation of nasopharyngeal carcinoma(NPC) is associated with Epstein-Barr virus(EBV) infection and telomerase activation. The EBV latent membrane protein 1(LMP1) regulates expression of various genes by triggering NF-κB signaling pathway. PINX1 is a well-identified tumor suppressor gene by inhibiting telomerase activity and cancer cell growth. However, whether and how EBV inhibit PINX1 expression and activate telomerase in NPC is still incompletely elucidated.MethodsImmunohistochemistry, real-time PCR and Western blotting were utilized to explore the expression of PINX1. Chromatin immunoprecipitation(ChIP) and Dual-luciferase reporter assay were used to elucidate the regulatory mechanism between NF-κB and PINX1. TRAP-SYBR Green assay and Southern blotting were utilized to detect telomerase activity and telomere length. CCK8 and EdU tests were conducted to measure proliferation ability.ResultsWe demonstrated that PINX1 is down-regulated in NPC for the first time. Mechanistically, we found that LMP1 could inhibit the transcriptional activity of PINX1 by promoting the binding of p65 to three specific sites in PINX1 promoter, significantly, two(-1698/-1689, tgcaatttcc; −206/-197, cgggctttac) of which have not been reported. In addition, we also observed that LMP1 overexpression resulted in increased telomerase activity, prolonged telomere length and enhanced proliferation.ConclusionWe first discovered EBV led to reduced PINX1 expression through LMP1-NF-κB-PINX1 axis, which up-regulated telomerase activity in NPC. And hence, the tumor cells acquired the ability to proliferate more exuberantly. This signaling pathway illustrates the relationship between EBV latent infection and telomerase activation, and further provides new thinking for early diagnosis and treatment in NPC.