Abstract 254: Triggering head and neck cancer cell cornification leads to mucosa-like differentiation, chromatin remodeling, and loss of cell malignancy
Authors: Oppel Felix , Gendreizig Sarah , Martinez-Ruiz Laura , Florido Javier , López-Rodríguez Alba , Pabla Harkiren , Loganathan Lakshna , Hose Leonie , Kühnel Philipp , Schmidt Pascal , Schürmann Matthias , Neumann Judith M. , Ful Flavian Viyof , Scholtz Lars Uwe , Todt Ingo , Dina Ligum , Brasch Frank , Karsten Niehaus , Escames Germaine , Busche Tobias , Kalinowski Jörn , Goon Peter , Sudhoff Holger 
Published: March 2024

Abstract
Head and neck squamous cell carcinoma (HNSCC) is the 6th most common tumor disease worldwide with a death rate of about 50%. As mortality and morbidity of affected patients were not substantially improved in recent decades, new treatment options are urgently needed. HNSCCs that are negative for the human papillomavirus are characterized by areas of differentiated keratinized tissue. Dissecting the mechanisms regulating this terminal differentiation of HNSCC cells may unravel targets with high potential for anti-tumor therapy. Using primary tumor-initiating spheroid cells, we established a model of HNSCC cell differentiation by cornification and observed a deprivation of cell malignancy leading to the adhesion of spheroid cells, loss of single-cell cloning capacity, and diminished tumor-initiating potential in immunodeficient mice. Analysis of our differentiation model employing ATAC-seq, RNA-seq, and proteomics showed an increased accessibility of small promoter regions despite overall genome closure, activation of a wound healing-associated signaling program, and upregulation of the stress keratin 17 (KRT17) as well as cornification markers including SPRR3. These results suggest that the differentiation of HNSCC cells resembles the differentiation process in other stem cell-maintained tissue systems. Multi-marker immunofluorescence analysis of human tissue revealed a reversion of the role of KRT17 from a basal stem-cell marker in normal mucosa to an early differentiation marker in HNSCC tissue and dysplastic mucosa preceding cornification. This proposes KRT17 as potential biomarker for HNSCC prevention screening. Human tissue analysis identified distinct cell differentiation states shared between HNSCC tissue and normal mucosa that were detected in higher and lower differentiated tumor tissue of distinct anatomical sub-locations. Cornification was observed to be induced at the interface between vital tumor tissue and necrotic, immune-infiltrated areas in human HNSCCs, suggesting a promoting influence of pro-inflammatory stimuli on cell differentiation. Treatment of tumor spheroids with inflammatory mediators resulted in cell attachment and cornification, indicating a potential strategy to stop the self-renewal of HNSCC cells. Our study thus reveals that the targeted differentiation of HNSCC tumor-initiating cells could be used as a future therapy approach against squamous cell carcinomas of the head and neck and other tissues.
Citation Format: Felix Oppel, Sarah Gendreizig, Laura Martinez-Ruiz, Javier Florido, Alba López-Rodríguez, Harkiren Pabla, Lakshna Loganathan, Leonie Hose, Philipp Kühnel, Pascal Schmidt, Matthias Schürmann, Judith M. Neumann, Flavian Viyof Ful, Lars Uwe Scholtz, Ingo Todt, Ligum Dina, Frank Brasch, Niehaus Karsten, Germaine Escames, Tobias Busche, Jörn Kalinowski, Peter Goon, Holger Sudhoff. Triggering head and neck cancer cell cornification leads to mucosa-like differentiation, chromatin remodeling, and loss of cell malignancy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 254.