Pan-Cancer Analysis of the Antigen-processing Gene PSMB8 as an Immunologic and Prognostic Biomarker

Recently some evidences have demonstrated the significance of PSMB8 in various malignancies. Nevertheless, PSMB8 (proteasome subunit beta 8), more familiar in the field of immunology contributing to the process of antigen presentation, is indeterminate in the role as a survival predictor of human pan-cancer. Besides, how PSMB8 interacts with immune cell infiltration in the tumor microenvironment requires further research. We then penetrated into the analysis of PSMB8 expression profile among 33 types of cancer in TCGA database. The results show that overexpression of PSMB8 was associated with the poor clinical outcomes in overall survival (OS), disease-specific survival (DSS), disease-free interval (DFI) and progression-free interval (PFI) in most cancer varieties. In addition, there existed distinctly positive correlations between PSMB8 and immunity, reflected straightfowardly in the form of immune scores, tumour-infiltrating immune cells (TIICs) abundance, microsatellite instability, tumour mutation burden, and neoantigen level. Notably, specific markers of dendrite cells exhibited the tightest association with PSMB8 expression in terms of tumor-related immune infiltration patterns. Moreover, gene enrichment analysis showed that elevated PSMB8 expression was related to multiple immune-related pathways. We finally validated the PSMB8 expression in our local breast samples via quantitative pCR assays and concluded that PSMB8 appeared to perform well in predicting the survival outcome of BRCA patients. These findings elucidate the pivotal role of the antigen presentation-related gene PSMB8, which could potentially serve as a robust biomarker for the prognosis determination in multiple cancers.