Exosomal miR-1290 and miR-375 as prognostic markers in castrate resistant prostate cancer

Extracellular microRNAs (miRNAs) embedded in circulating exosomes may serves as prognostic biomarkers in cancer. This study was performed to identify and evaluate plasma exosomal miRNAs for prognostication in castration resistant prostate cancer (CRPC). RNA sequencing was performed to identify candidate exosomal miRNAs associated with overall survival in a screening cohort of 23 CRPC patients. Candidate miRNAs were further evaluated for prognosis using qRT-PCR in a follow-up cohort of 100 patients. Cox regression and Kaplan–Meier survival curve analysis were used to evaluate prognostic value of miRNA candidates with and without incorporation of clinical prognostic factors (age, Gleason score and time from androgen deprivation therapy to clinical progression). In the screening cohort, we obtained ~6.80 million mappable RNA reads per patient. Of those with normalized read counts ? 5, 43% were mapped to miRNAs for a total of 375 known and 57 novel miRNAs. Cox regression analysis identified an association of miR-1290, -1246, and -375 with overall survival (FDR<0.1). Of those, higher levels of miR-1290 and -375 were verified to be significantly associated with poor overall survival (p<0.004) in the follow-up cohort. The miR-1290/-375-based prediction model showed better performance with time-dependent area under the curve (AUC) =72% compared to clinical variable-based model with AUC=65%. Plasma exosomal miR-1290 and miR-375 are promising prognostic biomarkers for CRPC patients. Prospective validation is needed for further development of these candidate miRNAs.