Prostate Cancer Specific Exosomal miRNAs in Saliva: a Way to a New and Dependable Screening Method

Abstract Background: Today, prostate cancer (PCa) is by far the most common cancer type among men. Diagnostic tests for PCa usually involve blood level testing of prostate-specific antigen (PSA) and transrectal, ultrasound-guided biopsy of the prostatic gland. Both diagnostic tools are unsatisfying in terms of low specificity and poor sensitivity. A general characterization of prostate cancer is difficult since the course of the disease varies individually from latent slow growing to aggressive and rapidly lethal tumors. However, no matter the severity of the disease, a possibility to increase the prognostic chances is the early detection. Regular cancer screening can be an appropriate concept if the tools are right. So far, PSA reaches its limits when it comes to an accurate distinction between cancerous glands and benign processes. miRNAs offer hope to overcome these drawbacks by virtue of their cancer-specific expression. Circulating miRNAs are an active area of current investigation and hold promise to serve a wide range of clinical applications and unwrap a new era in cancer diagnosis and therapeutics. miRNAs have proven their diagnostic potential of becoming a biomolecule of clinical relevance in a variety of human body fluid like blood/serum, urine, and saliva.Methods: We measured expression levels of 16 circulating prostate cancer specific miRNAs in saliva exosomes via qRT-PCR and compared differences between men suffering from prostate cancer and men suffering from other diseases of the urogenital tract, which formed the no-cancer control group. Differentiation strength of significant sequences was determined via ROC curve analysis. Results: hsa-mir-331 and hsa-mir-200b were significantly reduced in patients suffering from prostate cancer compared to the no-caner control group. Diagnostic quality of determined cut off values showed moderate differentiation strength with dependable diagnostic properties. The other 14 examined prostate cancer specific microRNAs showed no significant group differences. Conclusions: hsa-mir-331 and hsa-mir-200b are promising biomarkers for a reliable non-invasive and saliva-based test method in prostate cancer diagnostics. In a synopsis of the results in other studies and against the background of the chastening results of the other miRNAs analyzed, this is exciting news.