MicroRNAs (miRNA) detection in urine samples may be a scarce invasive approach for diagnosis and monitoring prostate cancer (PCa). The role of miR-191-5p in prostate oncogenesis, as well as its function as a potential diagnostic and prognostic biomarker has been described in many cancers. However, its role as a diagnostic non-invasive indicator in PCa is still under investigated.

We performed an extracellular vesicle (EV)-based miRNA-sequencing of urine samples (n = 12/group) collected from PCa patients before (T0) and three months after (T1) radical prostatectomy, and healthy individuals. An independent cohort of PCa paired urine samples (n = 25/group) and controls (n = 22) was used to validate our sequencing data by RT-qPCR. Furthermore, we conducted comprehensive in silico analyses on urine and tissue samples extracted from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases, respectively. Receiver operator curves analysis was employed to assess the diagnostic value of miR-191-5p. To explore the role(s) of miR-191-5p in prostate carcinogenesis, we predicted miR-191-5p potential targets using four miRNA/target-gene pair databases (i.e., miRDB, miRTarBase, TarBase, and TargetScan). Finally, we corroborated the potential correlation between miR-191-5p and its targets by in silico investigation using TCGA dataset.

Differential expression analysis revealed a significant upregulation of miR-191-5p in PCa patients compared to healthy individuals. Remarkably, urinary miR-191-5p expression levels significantly decreased after surgery in both our discovery and validation cohorts of urine samples by miRNA-seq and RT-qPCR, respectively. Bioinformatics analyses further confirmed high levels of miR-191-5p in urine and tissue samples from PCa patients compared to controls, particularly in patients with high Gleason score. Moreover, miR-191-5p showed a strong diagnostic value in urine and tissue samples. Finally, target prediction analysis identified the genes Satb1 and Ctdsp2 as potential targets of miR-191-5p. This was supported by a significant inverse correlation between the expression of miR-191-5p and these genes in TCGA PCa tissues. Moreover, both Satb1 and Ctdsp2 were downregulated in PCa tissues, and especially in high Gleason score tumors compared to normal and low Gleason score samples.

MiR-191-5p is highly expressed in urine and tissue samples from patients with prostate cancer. Our findings, although preliminary, support miR-191-5p as a promising minimally invasive biomarker for diagnosis of PCa patients.