Among the 49 significant DEGs in the NOM, SIN, and HNSCC groups (Fig. 4b, Online Resource 6), the hypoxia-inducible factor-1 alpha (HIF-1α) and interferon-gamma (IFN-γ) pathways were significantly upregulated in HNSCC compared to NOM and SIN, with further upregulation observed relative to SIN (Online Resource 7). Here, HIF1A is linked to head and neck squamous cell carcinoma.