Front Med (Lausanne). 2020 Aug 7;7:401. doi: 10.3389/fmed.2020.00401. eCollection 2020.
Using unbiased proteomics, we had previously discovered that the catalytic proteasome subunit β type 7 (PSB7) protein is frequently overexpressed in colorectal adenocarcinomas. In this paper, we validate this finding and derive a prognostic significance for PSB7 by examining an expanded, well-annotated clinical cohort of 318 colorectal cancer patients. We found PSB7 protein levels to be similarly increased in both advanced stage primary disease and metastatic lesions. We then examined the
prognostic value of PSB7 protein expression. Elevated PSB7 protein as well as PSMB7 mRNA levels showed associations with lower overall survival, particularly in female patients. The prognostic value of elevated PSB7 protein levels was highest for female patients who were older (>60 years of age at diagnosis) or who had received adjuvant chemotherapy. While high PSB7 did not retain its prognostic significance on multivariate analysis, we discuss the potential significance of PSB7 as a biomarker, considering its differential prognostic strength in different colorectal cancer patient groups and given its role as a subunit of the immunoproteasome for antigen presentation.