Abstract 4009: Interaction between NF-κB and NRF2 pathways lead to improved outcomes in HPV-associated head and neck cancer
Authors: Kothari Aditi , Schrank Travis Parke , Issaeva Natalia , Yarbrough Wendell Gray 
Published: June 2022

Abstract
HPV infection has been linked with various types of cancers. Current vaccines are likely to have limited impact in the prevention of head and neck squamous cell carcinoma (HNSCC) in several decades due to a high prevalence of this infection in older individuals. HPV-associated (HPV+) HNSCC is the most frequently diagnosed HPV related cancer and its incidence continues to rise. Despite this, little is known about the mechanism of HPV-driven carcinogenesis. Even though HPV+ HNSCC has a favorable prognosis, around 30% of patients show recurrence accompanied by severe side effects due to intensive radiotherapy. Hence, it is pertinent to develop de-intensification strategies to identify patients that are at low risk of recurrence. However, absence of molecular biomarkers greatly limits these studies. Data from two independent patient cohorts helped identify subtypes of HPV+ HNSCC based on presence or absence of NF-κB activating mutations. The subtype with NF-κB overactivity significantly correlated with better patient survival and the absence of an integrated HPV, suggesting that these tumors are driven by a distinct mechanism of oncogenesis, dependent on NF-κB overactivity and maintenance of episomal HPV. Most of these tumors had deletions of TRAF3 or CYLD genes, which are known NF-κB inhibitors. Another finding from this study was the presence of NRF2 downregulation in the subset of NF-κB overactive tumors. NRF2 is a major regulator of the cellular oxidative stress response. Its dysregulation has been known to help cancer cells survive and plays a role in radio resistance. We confirmed that baseline and inducible NRF2 transcriptional activity is downregulated in NF-κB overactive HPV+ HNSCC cells with TRAF3 or CYLD knockout. Interestingly, similar results were observed in these cells after overexpression of dominant negative CUL3 that stabilizes and activates NRF2, suggesting that stabilized NRF2 is inhibited in HPV+ HNSCC cells carrying constitutively active NF-κB. Clonogenic survival assay revealed that NF-κB active cells are more sensitive to radiation as compared to parental HPV+ HNSCC cells. In addition, we found lesser nuclear localization of NRF2 after treatment with small molecule NRF2 activator CDDO in CYLD/TRAF3 knockout cells. Confirmation of these findings post radiation may explain improved survival of patients with NF-κB overactive HPV+ HNSCC. Overall, our data suggests an inverse correlation between NF-κB and NRF2, with NF-κB potentially altering the oxidative stress response and conferring radio sensitivity to HPV+ HNSCC with TRAF3/CYLD mutations. Our aim is to uncover the unique mechanism of HPV carcinogenesis and finding novel therapeutic targets in HNSCC while improving quality of life in patients. Importantly, constitutively active NF-κB distinguishing the 2 subtypes of HPV+ HNSCC may serve as prognostic biomarkers to help clinicians with therapeutic decisions.
Citation Format: Aditi Kothari, Travis Parke Schrank, Natalia Issaeva, Wendell Gray Yarbrough. Interaction between NF-κB and NRF2 pathways lead to improved outcomes in HPV-associated head and neck cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4009.