Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Oncogene. 2012 Jul 26;31(30):3525-35. doi: 10.1038/onc.2011.520. Epub 2011 Nov 14.
The NF-κB transcription factor has a central role in diverse processes, including inflammation, proliferation and cell survival, and its activity is dysregulated in diseases such as autoimmunity and cancer. We recently identified the TRE17/ubiquitin-specific protease 6 (USP6) oncogene as the first de-ubiquitinating enzyme to activate NF-κB. TRE17/USP6 is translocated and overexpressed in aneurysmal bone cyst (ABC), a pediatric tumor characterized by extensive bone degradation and inflammatory recruitment. In the current study, we explore the mechanism by which TRE17 induces activation of NF-κB, and find that it activates the classical NF-κB pathway through an atypical mechanism that does not involve IκB degradation. TRE17 co-precipitates with IκB kinase (IKK), and IKK activity is augmented in stable cell lines overexpressing TRE17, in a USP-dependent manner. Optimal activation of NF-κB by TRE17 requires both catalytic subunits of IKK, distinguishing its mechanism from the classical and non-canonical pathways, which require either IKKβ or IKKα, respectively. TRE17 stimulates phosphorylation of p65 at serine 536, a modification that has been associated with enhanced transcriptional activity and nuclear retention. Induction of S536 phosphorylation by TRE17 requires both IKKα and IKKβ, as well as the IKKγ/NEMO regulatory subunit of IKK. We further demonstrate that TRE17(long) is highly tumorigenic when overexpressed in NIH3T3 fibroblasts, and that inhibition of NF-κB significantly attenuates tumor formation. In summary, these studies uncover an unexpected signaling mechanism for activation of classical NF-κB by TRE17. They further reveal a critical role for NF-κB in TRE17-mediated tumorigenesis, and suggest that NF-κB inhibitors may function as effective therapeutic agents in the treatment of ABC.
NF-κB 转录因子在多种过程中发挥核心作用，包括炎症、增殖和细胞存活，其活性在自身免疫和癌症等疾病中失调。我们最近发现 TRE17/泛素特异性蛋白酶 6（USP6）癌基因是第一个激活 NF-κB 的去泛素化酶。TRE17/USP6 在动脉瘤样骨囊肿（ABC）中易位和过度表达，ABC 是一种儿科肿瘤，其特征是广泛的骨降解和炎症募集。在本研究中，我们探讨了 TRE17 诱导 NF-κB 激活的机制，并发现它通过不涉及 IκB 降解的非典型机制激活经典 NF-κB 途径。TRE17 与 IκB 激酶（IKK）共沉淀，并且在稳定过表达 TRE17 的细胞系中，USP6 依赖性地增强了 IKK 的活性。TRE17 对 NF-κB 的最佳激活既需要 IKK 的两个催化亚基，又将其机制与经典和非经典途径区分开来，经典和非经典途径分别需要 IKKβ 或 IKKα。TRE17 刺激 p65 丝氨酸 536 的磷酸化，这种修饰与增强的转录活性和核保留有关。TRE17 诱导 S536 磷酸化既需要 IKKα 和 IKKβ，也需要 IKKγ/NEMO IKK 的调节亚基。我们进一步证明，在 NIH3T3 成纤维细胞中过度表达 TRE17(long) 具有高度致瘤性，而 NF-κB 的抑制显著减弱了肿瘤的形成。总之，这些研究揭示了 TRE17 激活经典 NF-κB 的意外信号机制。它们进一步揭示了 NF-κB 在 TRE17 介导的肿瘤发生中的关键作用，并表明 NF-κB 抑制剂可能作为 ABC 治疗的有效治疗剂。
