Expression of PSMD2 gene in hepatocellular carcinoma and its correlation with immune checkpoints and prognosis.

Hepatocellular carcinoma (HCC) is a prevalent and fatal tumor globally, characterized by a complex pathogenesis and poor prognosis. Despite significant advancements in the application of immune checkpoint inhibitors (ICIs) for cancer treatment, the efficacy of immunotherapy in HCC remains suboptimal. PSMD2, a crucial regulator of the ubiquitin-proteasome system, has attracted increasing attention for its involvement in various cancers; however, its functions and mechanisms in HCC are still poorly understood. This study aims to investigate the expression of PSMD2 in HCC, its association with prognosis, and its interaction with immune checkpoints, thus establishing a foundation for further exploration of its role in immune evasion in HCC. We analyzed the expression levels of PSMD2 in HCC and adjacent normal tissues utilizing the GEPIA and TIMER databases. Cox regression analysis was performed using R software to evaluate the relationship between PSMD2 expression and prognosis. Furthermore, we assessed the correlation between PSMD2 and immune cell infiltration, as well as immune checkpoints, including PD1, PD-L1, and CTLA-4, using R tools. Additionally, we examined the association between PSMD2 expression and immune therapy response through Tumor Immune Dysfunction and Exclusion (TIDE) analysis. Finally, we constructed a protein-protein interaction (PPI) network using the STRING database and Cytoscape software, followed by Gene Set Enrichment Analysis (GSEA). PSMD2 was significantly overexpressed in HCC and was closely correlated with poor prognosis (HR = 1.61, P = 2.0e-4). Immune infiltration analysis demonstrated that PSMD2 was positively correlated with several immune checkpoint genes, including PD1, PD-L1, and CTLA-4, as well as various immune cell types. TIDE analysis indicated that elevated PSMD2 expression was significantly associated with increased immune evasion potential and a poor response to immunotherapy. Furthermore, GSEA enrichment analysis revealed that PSMD2 is primarily enriched in the p53 signaling pathway, the ubiquitin-mediated proteolysis pathway, and other cancer-related pathways. The elevated expression of PSMD2 in HCC is not only correlated with poor prognosis but may also play a role in immune evasion by modulating tumor immunity, thereby affecting patient responses to immunotherapy. Consequently, PSMD2 presents a promising novel therapeutic target and potential biomarker for immunotherapy in HCC.