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 3

HPV16 E7 attenuates STING-induced innate immune signaling.

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HPV16 E7 attenuates STING-induced innate immune signaling. (A) 93VU147T ...
(A) 93VU147T cells were transduced with empty vector (EV) control or shNLRX1-expressing lentiviruses to produce stable control and NLRX1-deficient cell lines, which were then transfected with 1.0 μg/mL HA-tagged STING plasmid and incubated for 16 hours. STING protein complexes were immunoprecipitated using anti-HA affinity matrix followed by immunoblotting for the indicated potential binding partners. Experiments were performed 3 times, and representative blots are shown. (B) The protein lysates of HPV+ 93VU147T, UDSCC2, UMSCC47, and SCC90 as well as HPV– FaDu and PCI-13 cells were harvested on ice and separated by SDS-PAGE. Endogenous expression levels of HPV16 E7 and STING were then detected with respective antibodies. (C–E) 93VU147T, UMSCC47, and FaDu cells were transfected with 1.0 μg/mL STING plasmid and incubated for 24 hours with or without introduction of 1.5 μg/mL HPV16 E7 plasmid. Cell lysates were immunoblotted with HPV16 E7, STING, and markers for IFN-I activation. Densitometry analysis was performed using ImageJ and is shown in the lower panels. Comparisons between 2 groups were made by 2-tailed unpaired t test, while comparisons between multiple groups were conducted by 1-way ANOVA test followed by Tukey’s multiple-comparisons test. Results displayed represent the mean ± SEM (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001). Each immunoblot represents 3 biological repeats, and representative blotting results are shown.