Prostate cancer (PCa) is one of the major cancers in men, but discrepancy between incidence and mortality calls for a careful approach to screening and diagnosis. Controversy between US Preventive Services Task Force recommendations and the outcomes clinical trials illustrate that the shortcomings of existing biomarkers and high demand in novel approaches for prostate cancer screening. Recent studies have suggested miRNAs as new candidates for cancer biomarkers. In this study, we have investigated the use of miRNAs found in cell-free nucleoprotein complexes and urine extracellular vesicles (EVs) as prostate cancer biomarkers.
Urine extracellular vesicles were isolated by standard ultracentrifugation protocols. Cell-free supernatant containing nucleoprotein complexes was obtained after 17.000g centrifugation. miRNA from supernatant and urine EVs were isolated as described previously (Lekchnov et al, Anal Biochem, 2016) and profiled using customized miRCURY LNA miRNA qPCR panels (Exiqon Ltd).
Profiling of the expression of 84 miRNAs in paired samples of urine supernatant and urine EVs of 10 healthy donors (HD), 10 PCa patients and 10 patients with benign prostatic hyperplasia (BPH) has identified subsets of miRNAs differentially expressed between the groups. Using ratio-based normalization miRNA pairs with significantly different expression were selected and verified in an independent sample of 15 HD, 15 PCa and 15 BPH patients. To facilitate highly specific PCa detection a stepwise diagnostic algorithm based on miRNA expression in HD group (median ± 2SD cut off values) and hierarchical analysis of analytical systems was proposed (Bryzgunova et al, PLoS One, 2019). Diagnostic panels developed using miRNA profiling data and comprised of 24 miRNAs (17 miRNA ratios) could classify PCa and BPH patients and HD with 100% specificity and 97.5% accuracy. Diagnostic system based on the expression of 5 miRNA pairs in urine (miR-30a: miR-125b, miR-425: miR-331, miR-29b: miR-21, miR-191: miR-200a, miR-331: miR-106b) can be potentially used to identify PCa.
The data shows promise of urine cell-free and vesicle cargo miRNA as prostate cancer biomarkers.
Clinical trial identification
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The study was supported by the Russian Science Foundation (no. 16-15-00124). Pavel P. Laktionov acknowledges financial support within the framework of the Russian state funded budget project # АААА-А17-117020210026-2 to the ICBFM SB RAS.
All authors have declared no conflicts of interest.