Analysis of biomarkers in plasma-derived exosomal RNA in prostate cancer and application in combinatorial treatments targeting signal transduction of androgen receptor

The first part of the study was aimed to investigate the expression levels of panels of small RNA markers for PCa using plasma samples from men with various stages of disease. Plasma samples from healthy donor and cancer patients were used to establish the best small RNA isolation method and qPCR efficiency and to set up and optimize a technique for the detection of miRNA, snoRNA, sdRNA and tRFs and evaluate their diagnostic prognostic, predictive, and monitoring potential. Expression analysis were done by Real-Time PCR of RNA extracted from 200 µL of plasma. The study demonstrates the feasibility of small RNA isolation method in plasma samples and detection by qPCR. The evaluation of the diagnostic and prognostic role of these miRNA on plasma samples from cancer patients should be confirmed. The second part of the study was aimed to investigate the role of AR-V7 and AR-FL to predict resistance to hormonal therapy (HT) in castration resistant prostate cancer (CRPC) and to develop a new methodological approach based on plasma-derived exosomal RNA. Blood samples were collected from 88 CRPC patients before first or second-line HT. RNA was isolated from extracellular vesicles and analysed for AR-FL and AR-V7 by ddPCR. AR-FL was detected in all patients, whereas 29% of these patients were AR-V7+ before starting hormonal therapy. There was a significant higher expression of AR-FL mRNA in AR-V7+ compared to AR-V7- patients (p<0.0001). Median PFS and OS were significantly longer in AR-V7- vs AR-V7+ patients (median PFS 25 vs 4 months, p<0.0001; median OS 9 vs 38 months, p<0.0001). The study suggests that resistance to ADT is associated to AR-V7 status, and that AR-FL expression may also identify a category of patients borderline for their response to HT. The third part of the study was aimed to evaluate the combined treatment of abiraterone (anti-AR pathway) and everolimus (mTOR inhibitor) in prostate cancer cell lines expressing the AR-V7. The combined treatment induced a significant increase of concentration-dependent cytotoxicity and apoptosis compared to single treatment strategy.