These four most consistently reported dysregulated miRNAs viz. miRNA-141, miRNA-375, miRNA-221 and miRNA-21 need to be further validated in terms of their regulatory potential in regulating various pathways important for prostate cancer management.
For example, we find multiple known (e.g., miR-20a-PTEN-PTENP1) and novel (e.g., miR-375-SOX15-PPP4R1L) microRNA-gene-pseudogene associations in prostate cancer.
We chose miRNA-375 and miRNA-574-3p as the target miRNAs for prostate cancer, and these markers in exosomes produced by prostate cancer cells including DU145 and PC-3 were successfully detected using molecular beacons.
Additional interesting findings were that the expression profiles of five miRNAs (miR-21, miR-30c, miR-129, miR-145, and let-7c) could predict poor RFS of PC, while the evaluation of miR-375 was associated with worse OS. miRNAs are important regulators in PC progression.
Sensitive and selective detection of prostate cancer biomarkers including miRNA-375, miRNA-141, and prostate-specific antigen on a single microchip is also achieved.
Relative expression ratios of miR-106b, miR-141-3p, miR-21, and miR-375 were significantly increased (1.8-, 1.9-, 2.4-, and 2.6-fold, respectively) in the PCa group compared to healthy control.
Promising preliminary results were published concerning miR-141, miR-375 and miR-21, but larger and prospective studies using standardized methodology are necessary to define the value of miRNAs in the detection and prognosis of PCa.
MiR-375 could differentiate between PC and BPH patients when analysed in the whole plasma, while miR-200c-3p and miR-21-5p performed better when analysed in plasma EVs.
Collectively, this study provides new insight into the function of miR-375 in prostate cancer, and more broadly identifies a novel pathway controlling epithelial plasticity and tumor cell invasion in this disease.
More importantly, the PNI sensor successfully detected the extracellular miR141 and miR375 released from living PC cell lines (LNCaP and PC-3), proving the diagnostic ability of the sensor for PC.
Furthermore, miR-375 enhanced proliferation, migration and invasion in vitro and induced tumor growth and reduced survival in vivo showing that miR-375 has oncogenic properties in prostate cancer.
Combinations of serum prostate-specific antigen and plasma expression levels of let-7c, miR-30c, miR-141, and miR-375 as potential better diagnostic biomarkers for prostate cancer.
The reduced levels of Sec23A protein were inversely correlated to the increased amount of miR-375 in the LNCaP and DU145 CaP cell lines when compared with normal prostate fibroblasts.