USP5 Promotes Head and Neck Squamous Cell Carcinoma Progression via mTOR Signaling Pathway

ABSTRACT Background Head and neck squamous cell carcinoma (HNSCC) is a highly aggressive malignancy characterized by limited prognostic markers and treatment options, contributing to high mortality rates. While Ubiquitin‐specific peptidase 5 (USP5) has been implicated in various cancers, its role in HNSCC remains poorly understood. Aims This study aims to investigate the role of USP5 in the progression of HNSCC and explore its potential as both a prognostic biomarker and a therapeutic target. Materials & Methods This work utilized single‐cell transcriptomic analysis with the Scissor algorithm to identify distinct epithelial subpopulations, particularly focusing on the Stress subpopulation that exhibited significant upregulation of USP5. Validation was conducted using tissue microarray (TMA) analysis and immunohistochemistry (IHC) to compare USP5 expression levels in HNSCC tissues versus adjacent normal tissues. Furthermore, RNA interference (RNAi) experiments were performed to knock down USP5 expression, assessing its effects on tumor cell behavior, including proliferation, migration, and invasion, as well as the regulation of mTORC1 and NF‐κB signaling pathways. Results This study revealed that the Stress subpopulation, characterized by USP5 upregulation, was associated with enhanced tumor cell proliferation, migration, and invasion. TMA and IHC analyses confirmed that USP5 expression was significantly higher in HNSCC tissues compared to normal tissues, correlating with poor patient prognosis. Additionally, RNAi‐mediated knockdown of USP5 led to reduced tumor cell activities and downregulation of the mTORC1 and NF‐κB signaling pathways. Discussion The findings suggest that USP5 plays a critical role in driving HNSCC progression. Its overexpression in aggressive tumor subpopulations and association with poor clinical outcomes highlight its potential utility as both a prognostic biomarker and a therapeutic target. The observed effects on cell behavior and oncogenic signaling pathways provide mechanistic insights into how USP5 for HNSCC therapy. Conclusions This study establishes USP5 as a key driver of HNSCC progression, underscoring its potential role in prognosis and therapy. Targeting USP5 may offer novel treatment strategies for HNSCC, addressing the urgent need for effective therapeutic interventions in this aggressive malignancy.