Urinary Extracellular Vesicle Signatures as Biomarkers in Prostate Cancer Patients

Urinary extracellular vesicles (U-EVs) are gaining increasing interest as non-invasive liquid biopsy tools for clinical use. Prostate cancer (PCa) is amongst the highest cancer-related cause of death in men, and therefore, the identification of non-invasive robust biomarkers is of high importance. This study assessed U-EV profiles from individuals affected by PCa at Gleason scores 6-9, compared with healthy controls. U-EVs were characterised and assessed for proteomic cargo content by LC-MS/MS analysis. The U-EV proteomes were compared for enrichment of gene ontology (GO), KEGG, and Reactome pathways, as well as disease-gene associations. U-EVs ranged in size from 50 to 350 nm, with the majority falling within the 100-200 nm size range for all groups. U-EV protein cargoes from the PCa groups differed significantly from healthy controls, with 16 protein hits unique to the GS 6-7 and 88 hits to the GS 8-9 U-EVs. Pathway analysis showed increased enrichment in the PCa U-EVs of biological process GO (5 and 37 unique to GS 6-7 and GS 8-9, respectively), molecular function GO (3 and 6 unique to GS 6-7 and GS 8-9, respectively), and cellular component GO (10 and 22 unique to GS 6-7 and GS 8-9, respectively) pathways. A similar increase was seen for KEGG pathways (11 unique to GS 8-9) and Reactome pathways (102 unique to GS 8-9). Enrichment of disease-gene associations was also increased in the PCa U-EVs, with highest differences for the GS 8-9 U-EVs (26 unique terms). The pathway enrichment in the PCa U-EVs was related to several key inflammatory, cell differentiation, cell adhesion, oestrogen signalling, and infection pathways. Unique GO and KEGG pathways enriched for the GS 8-9 U-EVs were associated with cell-cell communication, immune and stress responses, apoptosis, peptidase activity, antioxidant activity, platelet aggregation, mitosis, proteasome, mRNA stability oxytocin signalling, cardiomyopathy, and several neurodegenerative diseases. Our findings highlight U-EVs as biomarkers to inform disease pathways in prostate cancer patients and offer a non-invasive biomarker tool for clinical use.