The role of HPV E1 in regulating the NRF2-KEAP1 pathway

仅持续的HPV感染就与全球癌症总发病率的4.5%有关，并可能导致多达六种不同的癌症。HPV阳性的HNSCC的全球发病率目前正在上升，特别是在年轻人中。尽管与HPV-HNSCC相比，这些肿瘤对治疗的反应更容易，但部分患者(约10%)将无法接受治疗。HPV+癌症的全球健康负担和与HPV相关的HNSCC发病率不断上升，突显了扩大我们对HPV生物学的知识的必要性，以指导靶向治疗的设计。越来越多的文献强调了NRF2在HPV相关癌症中的作用。由于NRF2与许多癌症有关，包括约30%的实体瘤，以及它们对治疗的失败，这一途径提供了一个潜在的治疗脆弱性，可能成为慢性HPV感染和HPV相关癌症的靶点。到目前为止，我们对NRF2是如何在HPV感染的细胞中被激活的了解还不完全。最近发现HPV E1与Keap1直接相互作用，我们已经证实了这一发现。这种相互作用使CUL3-Keap1-NRF2途径中的突变失活，从而激活NRF2的转录活性。目前尚不清楚E1如何与Keap1结合来激活NRF2，以及这一E1功能在不同HPV类型中的保守性。在这项提案中，我们将确定HPV E1激活NRF2的分子机制。我们假设E1作为病毒NRF2模拟物来竞争Keap1结合。这一假设将通过两个具体目标进行检验。在目标1中，我们将建立E1Keap1和NRF2激活的分子决定因素。我们还将评估高危和低危HPV类型结合Keap1和激活NRF2的能力。在AIM2中，我们将确定E1-Keap1相互作用的结构和生物物理基础。本项目的最终目的和总体影响是促进我们对HPV通过激活性病毒蛋白E1调节NRF2信号通路的理解。这项工作反过来将使我们能够研究E1-Keap1-NRF2轴作为一种新的脆弱性，可以作为慢性HPV感染和HPV相关癌症的靶点，这些癌症目前缺乏靶向治疗。

Persistent HPV infections alone are linked to ~ 4.5% of the total cancer incidence worldwide and can cause up to six different cancers. The global incidence of HPV-positive HNSCC is currently on the rise, particularly among younger adults. Despite these tumors responding more readily to treatment compared to HPV- HNSCC, a subset of patients (~10%) will fail therapy. The global health burden of HPV+ cancers and the growing incidence of HPV-related HNSCC underscore the need to expand our knowledge of HPV biology to inform the design of targeted therapeutics. A growing body of literature highlights the function of NRF2 in HPV-associated cancers. As NRF2 is implicated in numerous cancers, including ~30% of solid tumors, and their failure to respond to therapies, this pathway provides a potential therapeutic vulnerability that could be targeted in chronic HPV infection and HPV-associated cancers. To date, we have an incomplete understanding of how NRF2 is activated in HPV-infected cells. It was recently discovered that HPV E1 directly interacts with KEAP1 and we have validated this finding. This interaction phenocopies inactivating mutations in the CUL3-KEAP1-NRF2 pathway to activate NRF2 transcriptional activity. How E1 binds to KEAP1 to activate NRF2 and the conservation of this E1 function across different HPV types is currently unknown. In this proposal, we will determine the molecular mechanism by which HPV E1 activates NRF2. We hypothesize that E1 functions as a viral NRF2 mimetic to compete for KEAP1 binding. This hypothesis will be tested through 2 specific aims. In Aim 1, we will establish the molecular determinants for E1 engagement of KEAP1 and NRF2 activation. We will also assess the ability of both high-risk and low-risk HPV types to bind KEAP1 and activate NRF2. In Aim2, we will determine the structural and biophysical basis for E1-KEAP1 interactions. The ultimate goal and the overall impact of this project are to advance our understanding of HPV regulation of NRF2 signaling by the agonistic viral protein E1. This work will in turn enable us to study the E1-KEAP1-NRF2 axis as a novel vulnerability that could be targeted in chronic HPV infection and HPV-associated cancers, which currently lack targeted therapy.