Non-invasive prostate cancer detection by measuring miRNA variants (isomiRs) in urine extracellular vesicles

Abstract

In many cancer types, the expression and function of ∼22 nucleotide-long microRNAs (miRNA) is deregulated. Mature miRNAs can be stably detected in extracellular vesicles (EVs) in biofluids, therefore they are considered to have great potential as biomarkers. In the present study, we investigated whether miRNAs have a distinct expression pattern in urine-EVs of prostate cancer (PCa) patients compared to control males. By next generation sequencing, we determined the miRNA expression in a discovery cohort of 4 control men and 9 PCa patients. miRNAs were validated by using a stemloop RT-PCR in an independent cohort of 74 patients (26 control and 48 PCa-patients). Whereas standard mapping protocols identified > 10 PCa associated miRNAs in urinary EVs, miR-21, miR-375 and miR-204 failed to robustly discriminate for disease in a validation study with RT-PCR-detection of mature miRNA sequences. In contrast, we observed that miRNA isoforms (isomiRs) with 3′ end modifications were highly discriminatory between samples from control men and PCa patients. Highly differentially expressed isomiRs of miR-21, miR-204 and miR-375 were subsequently validated in an independent group of 74 patients. Receiver-operating characteristic analysis was performed to evaluate the diagnostic performance of three isomiRs, resulting in a 72.9% sensitivity with a high (88%) specificity and an area under the curve (AUC) of 0.866. In comparison, prostate specific antigen had an AUC of 0.707 and measuring the mature form of these miRNAs yielded a lower 70.8% sensitivity and 72% specificity (AUC 0.766). We propose that isomiRs may carry discriminatory information which is useful to generate stronger biomarkers.

Emerging role of microRNA-21 in cancer

“…Downregulation of RECK and loss of BTG2 mediated by miR-21 was shown to contribute to prostate cell transformation (65,66). Furthermore, miR in prostate cancer tissues and in serum and urine samples of prostate cancer patients was revealed to be an independent diagnostic and prognostic biomarker (67)(68)(69).…”

“…The application of this non-invasive approach may be considered for monitoring responses of lung cancer patients to EGFR-TKI treatment (79). Furthermore, the implication of miR-21 in chemotherapy resistance has been investigated for a wide range of solid cancer types, including pancreatic and prostate cancer, hepatoma, ovarian cancer, glioma, and head and neck, stomach and bladder cancer (Table I) (68)(69)(70)(71)75,(77)(78)(79)(80)(81)(82)(83)(84)(85)(86)(87)(88)(89)(90)(91)(92)(93)(94). These results support the clinical application of miR-21 inhibition in cancer treatments in the future.…”

Prostate Cancer Detection and Prognosis: From Prostate Specific Antigen (PSA) to Exosomal Biomarkers

“…They are generated from a single miRNA locus through the miRNA processing and maturation process. Koppers-Lalic et al [96] identified that isomiRs of miR-21, miR-375 and miR-204 measured in urinary extracellular vesicles could distinguish control men from PCa patients. The authors found an AUC of 0.821 for these set of isomiRs, meanwhile the AUC corresponding to the mature miRNA was 0.661.…”

Beyond prostate-specific antigen

“…For instance, in just two weeks of Medline updates we found papers on long non-coding RNAs 52 , ALKBH3 53 , two different approaches to MicroRNAs 54,55 , a surface-enhanced Raman scattering (SERS)-based microdroplet sensor for PSA 56 , urinary carbonic anhydrase IX splicing messenger RNA 57 , prostate specific membrane antigen (PSMA) 58 , and platelet factor-4 (PF-4) 58 . Here we review some of the most prominent recent markers.…”