MiR-375 and miR-21 as Potential Biomarkers of Prostate Cancer: Comparison of Matching Samples of Plasma and Exosomes

MiR-21 and miR-375 have been reported as dysregulated in prostate cancer (PCa) in multiple previous studies. Still, variable or even opposing data for the expression of these microRNAs in PCa were found, and their potential biomarker properties remain elusive. In an attempt to clarify their significance as PCa biomarkers, as well as to compare different types of specimens as a source of relevant microRNAs, we used plasma and matching plasma-derived exosomes from patients with PCa and patients with benign prostatic hyperplasia (BPH). Plasma and exosomes were obtained from 34 patients with PCa and 34 patients with BPH, and their levels of expression of miR-21 and miR-375 were determined by RT-qPCR. We found no significant difference in the level of expression of these microRNAs in plasma and exosomes between patients with PCa and BPH. The level of exosomal miR-21 was elevated in PCa patients with high serum PSA values, as well as in patients with aggressive PCa, while for plasma samples, the results remained insignificant. For miR-375, we did not find an association with the values of standard prognostic parameters of PCa, nor with cancer aggressiveness. Therefore, our results support the potential prognostic role of exosomal miR-21 expression levels in PCa.

Affinity-based isolation of extracellular vesicles by means of single-domain antibodies bound to macroporous methacrylate-based copolymer

Correct elucidation of physiological and pathological processes mediated by extracellular vesicles (EV) is highly dependent on the reliability of the method used for their purification. Currently available chemical/physical protocols for sample fractionation are time-consuming, often scarcely reproducible and their yields are low. Immuno-capture based approaches could represent an effective purification alternative to obtain homogeneous EV samples. An easy-to-operate chromatography system was set-up for the purification of intact EVs based on a single domain (VHH) antibodies-copolymer matrix suitable for biological samples as different as conditioned cell culture medium and human plasma. Methacrylate-based copolymer is a porous solid support, the chemical versatility of which enables its efficient functionalization with VHHs. The combined analyses of morphological features and biomarker (CD9, CD63 and CD81) presence indicated that the recovered EVs were exosomes. The lipoprotein markers APO-A1 and APO-B were both negative in tested samples. This is the first report demonstrating the successful application of spherical porous methacrylate-based copolymer coupled with VHHs for the exosome isolation from biological fluids. This inexpensive immunoaffinity method has the potential to be applied for the isolation of EVs belonging to different morphological and physiological classes.