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 8

NLRX1 in cancer cells inhibits STING signaling in vivo and excludes functional effectors from TME.

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NLRX1 in cancer cells inhibits STING signaling in vivo and excludes func...
(A) Control and shNLRX1 MOC2-E6/E7 cells were stimulated by 1.0 μg/mL poly(dA:dT) for 16 hours, and qPCR was performed to quantitate the mRNA levels of indicated IFN-I signature genes. Experiments were performed 3 times. Comparisons between 2 groups were made using a 2-tailed unpaired t test (**P < 0.01, ****P < 0.0001). (B) Control and NLRX1-deficient MOC2-E6/E7 cells were transfected with 1.0 μg/mL expression plasmid encoding murine STING and incubated for 16 hours. Cell lysates were immunoblotted against the indicated markers. Immunoblotting results represent 2 independent repeats. (C) The proliferation of EV control and shNLRX1 MOC2-E6/E7 cells was measured by an alamarBlue assay. Each group included 5 replicate wells. Experiments were performed twice. (D) One million EV control or NLRX1-deficient MOC2-E6/E7 cells were implanted subcutaneously in the right flank of C57BL/6 hosts. Tumor measurements were performed every 2–3 days. Tumor burden was compared using the generalized estimating equations model (n = 8 in each group; *P < 0.05). In vivo experiments were performed 3 times with n = 19 total in each group. A representative set is shown. (E) Total RNA was isolated from 1 representative set of tumors and subjected to qPCR. (F) After harvesting of tumors, TILs of 1 representative set were isolated and analyzed by flow cytometry (n = 8 in control group, n = 4 in shNLRX1 group due to tumor rejection). (G) Lymphocytes were isolated from draining lymph nodes of 1 representative set and assessed by flow cytometry (n = 5 in each group). Comparisons between 2 groups from E–G were made using a 2-tailed unpaired t test (*P < 0.05, **P < 0.01). Quantifications indicate the mean ± SEM. Results represent 3 independent experiments.