NSD2 is upregulated by high-risk HPV E6/E7 and modulates epithelial differentiation in HPV-associated Head and Neck Cancer
Epigenetic alterations are a key hallmark of cancer and are increasingly recognized as promising clinical biomarkers and therapeutic targets. In recent years Head and Neck Squamous Cell Carcinomas (HNSCC) have been classified into two subtypes: HPV-positive (HPV+), driven by human papillomavirus (HPV) infections, and the HPV-negative (HPV-), associated with environmental risk factors. Although exhibiting distinct molecular and clinicopathological features, both subtypes lack effective, tailored therapies. Thus, profiling their epigenetic landscape could thus have important clinical implications. In this study, we employed a quantitative mass spectrometry approach to profile histone post-translational modification (hPTMs) in HPV+ and HPV- HNSCC. We found that the histone mark H3K36me2 is significantly enriched in the HPV+ subtype and that this alteration is driven by hr-HPV E6/E7 oncoproteins which also upregulate NSD2, a histone methyltransferase specific for H3K36 dimethylation. Both H3K36me2 and NSD2 are upregulated in several cancers. Given the NSD2's context and cell-type-dependent functions, we investigated its role in HPV+ and HPV- HNSCC. We observed that NSD2 regulates cell proliferation and migration in both the subtypes. Importantly, we identified a novel role for NSD2 in regulating epithelial cell differentiation, particularly in HPV+ HNSCC, where it appears to modulate the E6/E7-induced differentiation blockade. Overall, our findings highlight H3K36me2 as a potential biomarker for patient stratification and position NSD2 as a promising therapeutic target across HNSCC subtypes, regulating both shared and subtype-specific oncogenic pathways. Specifically, NSD2 inhibition in HPV+ tumors may restore epithelial differentiation and arrest tumor progression. Overall design: Four HPV- (UM-SCC-4, UM-SCC-6, UM-SCC-18, UM-SCC-19) and three HPV+ (UD-SCC-2, UM-SCC-104, UPCI:SCC-152) HNSCC cell lines were transduced with shNSD2 and scrambled (scr) as a control. To assess wheter common and/or different pathways are regulated in HPV+ and HPV- HNSCC subtypes, DEGs between shNSD2 and scr control were calculated for each subgroup.