miR-20b-5p is a novel biomarker for detecting prostate cancer

Prostate cancer (PCa) is the second most frequently diagnosed solid tumor and the fifth leading cause of cancer mortality among men worldwide. The prostate specific antigen (PSA) test for PCa remains controversial. Therefore, the development of more effective non-invasive biomarkers for PCa is necessary. The present study evaluated the diagnostic value of microRNA (miR)-20b-5p in PCa. Tissue miR-20b-5p expression levels and their correlation with clinical parameters were assessed using The Cancer Genome Atlas (TCGA) datasets, and the diagnostic value of the miR-20b-5p expression levels in PCa tissues was assessed using receiver operating characteristic curve analysis. Reverse transcription-quantitative PCR (RT-qPCR) was used to assess the relative expression levels of miR-20b-5p in PCa tissues compared with benign prostate hyperplasia (BPH) tissues. In addition, miR-20b-5p expression levels in PCa cell lines and non-tumorigenic prostate epithelial cells were compared. In this study, exosomes were extracted from the prostatic fluid as a source of liquid biopsy for the detection of PCa. The prostatic fluid exosomal miR-20b-5p expression levels between patients with PCa and the biopsy-negative patients were compared, and the diagnostic efficiency of prostatic fluid exosomal miR-20b-5p expression levels in PCa was compared with PSA and with the European Randomized Study of Screening for Prostate Cancer (ERSPC) risk calculator. The mechanism by which miR-20b-5p may function in PCa was assessed using bioinformatic analysis and validation experiments. miR-20b-5p was expressed at a markedly higher level in PCa tissues compared with normal prostate tissues with high diagnostic efficiency (area under the curve: 0.826). The expression levels of miR-20b-5p were also significantly higher in PCa tissues compared with BPH tissues; similarly, miR-20b-5p was more highly expressed in PCa cells compared with non-tumorigenic prostate epithelial cells. Prostatic fluid exosomal miR-20b-5p expression levels in patients with PCa were significantly higher compared with confirmed to be biopsy-negative, and the diagnostic performance of miR-20b-5p was superior to PSA and ERSPC risk calculator. The results of RT-qPCR and western blotting following transfection of DU145 cells with miR-20b-5p mimics and inhibitor showed that miR-20b-5p reduced the expression of retinoblastoma-associated protein 1 (RB1). Therefore, RB1 may be a significant target gene for miR-20b-5p. In conclusion, the present study demonstrated that miR-20b-5p was upregulated in PCa at the tissue and cellular levels, as well as in prostatic fluid exosomes. Therefore, miR-20b-5p may be a promising early diagnostic biomarker for PCa and an important tool to guide the decision-making of prostate biopsy.