HPV16 drives cancer immune escape via NLRX1-mediated degradation of STING
Xiaobo Luo, … , Qianming Chen, Yu L. Lei
Xiaobo Luo, … , Qianming Chen, Yu L. Lei
Published December 24, 2019
Citation Information: J Clin Invest. 2020;130(4):1635-1652. https://doi.org/10.1172/JCI129497.
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Research Article Immunology Oncology

HPV16 drives cancer immune escape via NLRX1-mediated degradation of STING

Abstract

The incidence of human papillomavirus–positive (HPV+) head and neck squamous cell carcinoma (HNSCC) has surpassed that of cervical cancer and is projected to increase rapidly until 2060. The coevolution of HPV with transforming epithelial cells leads to the shutdown of host immune detection. Targeting proximal viral nucleic acid–sensing machinery is an evolutionarily conserved strategy among viruses to enable immune evasion. However, E7 from the dominant HPV subtype 16 in HNSCC shares low homology with HPV18 E7, which was shown to inhibit the STING DNA-sensing pathway. The mechanisms by which HPV16 suppresses STING remain unknown. Recently, we characterized the role of the STING/type I interferon (IFN-I) pathway in maintaining immunogenicity of HNSCC in mouse models. Here we extended those findings into the clinical domain using tissue microarrays and machine learning–enhanced profiling of STING signatures with immune subsets. We additionally showed that HPV16 E7 uses mechanisms distinct from those used by HPV18 E7 to antagonize the STING pathway. We identified NLRX1 as a critical intermediary partner to facilitate HPV16 E7–potentiated STING turnover. The depletion of NLRX1 resulted in significantly improved IFN-I–dependent T cell infiltration profiles and tumor control. Overall, we discovered a unique HPV16 viral strategy to thwart host innate immune detection that can be further exploited to restore cancer immunogenicity.

Authors

Xiaobo Luo, Christopher R. Donnelly, Wang Gong, Blake R. Heath, Yuning Hao, Lorenza A. Donnelly, Toktam Moghbeli, Yee Sun Tan, Xin Lin, Emily Bellile, Benjamin A. Kansy, Thomas E. Carey, J. Chad Brenner, Lei Cheng, Peter J. Polverini, Meredith A. Morgan, Haitao Wen, Mark E. Prince, Robert L. Ferris, Yuying Xie, Simon Young, Gregory T. Wolf, Qianming Chen, Yu L. Lei

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Figure 5

Deletion of HPV16 E7 restores IFN-I signaling along with reduced autophagic activity.

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Deletion of HPV16 E7 restores IFN-I signaling along with reduced autopha...
(A and B) 93VU147T and UMSCC47 cells were transduced with lentivirus of CRISPR/Cas9 targeting E7, and the EV was considered as control. The established cell lines were transfected with STING agonist (cGAMP) or mock for 16 hours, and cell lysates were subjected to immunoblotting for HPV16 E7, STING, LC3B, phospho-TBK1, and TBK1. Representative blots of 2 repeats are presented. (C and D) 93VU147T and UMSCC47 cells with or without the expression of E7 were transfected with cGAMP for 16 hours, and total RNA was isolated. qPCR was then performed to quantitate the mRNA levels of indicated IFN-I signature genes. Values represent mean ± SEM of 3 biological replicates. Comparisons were made by 2-way ANOVA followed by Šidák’s post-test (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001). Experiments were performed 3 times. (E) 93VU147T and UMSCC47 cells with or without the expression of HPV16 E7 were transfected with cGAMP for 16 hours, and the protein levels of IFN-β from supernatant were determined by ELISA. Comparisons were made by 2-way ANOVA with Šidák’s post-test (***P < 0.001, ****P < 0.0001). Experiments were performed twice. (F) Left panel: Laser confocal analysis was conducted in EV or HPV16 E7–/– UMSCC47 cells, which were transfected with pEGFP-LC3B for 48 hours before the images were captured. Scale bars: 10 μm. Right panel: Quantitation of EGFP-LC3 puncta in each cell section of both groups was conducted. Comparisons between the 2 sets were completed using an unpaired 2-tailed t test. Values represent mean ± SEM (****P < 0.0001). n = 20 cell sections from 2 repeats.