MicroRNA expression profile of primary prostate cancer stem cells as a source of biomarkers and therapeutic targets

MicroRNA (miRNA) expression profiles were generated from prostate epithelial sub-populations, enriched from patient-derived benign prostatic hyperplasia (BPH, n=5), Gleason 7 treatment naïve prostate cancer (PCa, n=5) and castration-resistant prostate cancer (CRPC, n=3). Microarray expression was validated in an independent patient cohort (n=10). The analyses show that miRNA expression in epithelial sub-populations (e.g. stem cells) clustered together, irrespective of pathological status. We also discovered concordance between the miRNA expression profiles of unfractioned CRPCs, human embryonic stem cells (SCs), and prostate epithelial SCs (both, benign and malignant). miR-548c-3p was chosen as a candidate miRNA from this group to explore its utility as a CRPC biomarker and/or therapeutic target. Overexpression of miR-548c-3p was confirmed in cancer SCs (8-fold, p<0.05) and unfractionated CRPCs (1.8-fold, p<0.05). Enforced overexpression of miR-548c-3p in differentiated cells induced stem-like properties (p 0.01) and radioresistance (p<0.01). Re-analyses of published studies further revealed that miR-548c-3p is significantly overexpressed in CRPC (p<0.05) and is associated with poor recurrence-free survival (p<0.05), suggesting that miR-548c-3p is a functional biomarker for prostate cancer aggressiveness. Our results validate the prognostic and therapeutic relevance of miRNAs for advanced prostate cancer management, whilst demonstrating that resolving cell-type and differentiation-specific differences is essential to obtain clinical relevant miRNA expression profiles. There are 42 samples in total: 15 benign prostatic hyperplasia, 15 prostate cancers, 9 treatment-resistant prostate cancer. There are stem cells, transit amplifying cells and committed basal cells dissected from each sample. Three PrEC samples of each three cell types can be used as reference.