Abstract 6284: SUV420H1 as a novel target in HPV-negative head and neck squamous cell carcinoma

Human Papilloma Virus (HPV)-negative head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer type in the world and its outcomes are mostly unchanged for the past few decades, especially for HPV-negative HNSCC. The TCGA recently revealed a plethora of genetic alterations in chromatin modifiers in HPV-negative HNSCC, including protein lysine methyltransferases which methylate lysine residues on histone tails and regulate gene expression. One of these enzymes, SUV420H1, is known to trimethylate H4K20 and is recurrently amplified in approximately 6% of HPV-negative HNSCC tumors (TCGA). It has also been found to be significantly overexpressed in multiple HNSCC cell lines compared with normal keratinocytes. This study aims to investigate whether SUV420H1 has oncogenic activity and could be a novel therapeutic target in HPV-negative HNSCC. To evaluate the effect of SUV420H1 depletion on HPV-negative HNSCC cell lines, siRNA-mediated knockdown was performed in four SUV420H1 overexpressing HPV-negative HNSCC cell lines, and MTT assays showed significantly reduced cell viability by approximately 80-90% after 12 days of siRNA treatment. Colony formation assays, cell cycle analysis and apoptosis assays are ongoing, and these assays are planned in SUV420H1 CRISPR KO cell lines. Gene Set Enrichment Analysis in 434 HPV-negative HNSCC tumors (TCGA) showed significant enrichment of immune signatures, EMT, cell cycle and apoptosis pathways. Ongoing experiments aim to investigate the effects of SUV420H1 knockdown on the global histone methylome, and to identify direct downstream targets of SUV420H1 through combined genome-wide mapping of SUV420H1 using CUT&RUN assays and RNA-seq in HPV-negative HNSCC cell lines. Syngeneic and xenograft mouse models are also planned to evaluate the effect of SUV420H1 depletion on flank tumor growth in vivo. These studies may elucidate the oncogenic effects and mechanisms of SUV420H1, and may provide evidence to support SUV420H1 as a potential novel target in the treatment of HPV-negative HNSCC tumors with SUV420H1 amplification or overexpression. Citation Format: Arfa Moshiri, Hui Cheng, Sohyoung Kim, Vassiliki Saloura. SUV420H1 as a novel target in HPV-negative head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstrac