Novel biomarkers for the diagnosis of prostate cancer (PCa) are urgently required. Increasing evidence suggests that exosomal microRNAs (miRNAs or miRs) in serum may be potential noninvasive biomarkers for certain diseases. The objective of the present study was to investigate and assess whether exosomal miR-141 is an effective biomarker for human PCa.

In the present study, exosomes were isolated from the serum of patients with PCa, patients with benign prostate hyperplasia (BPH), and healthy volunteers. The total RNA was extracted from the exosomes and the level of miR-141 was analyzed by quantitative reverse transcription-polymerase chain reaction. The expression levels of miR-141 were compared between the whole serum and the serum exosomes of the three groups. Subsequently, the relevance of the exosomal expression of miR-141 to the clinicopathological factors in PCa was investigated.

The expression of miR-141 was higher in exosomes compared with whole serum (control group, P=0.0003; BPH group, P=0.0016; PCa group, P<0.0001). The level of serum exosomal miR-141 was significantly higher in the patients with PCa compared with the patients with BPH and the healthy controls (3.85-fold, P=0.0007 and 4.06-fold, P=0.0005, respectively). In addition, the expression levels were significantly higher in metastatic PCa compared with localized PCa (P<0.0001). Receiver-operating characteristic curve revealed that the serum exosomal miR-141 yielded an area under the curve of 0.8694, with 80% sensitivity and 87.1% specificity in discriminating patients with metastatic PCa from the patients with localized PCa.

Serum exosomes may serve as a more suitable material compared with the whole serum for measuring circulating miR-141 levels in patients with PCa. Exosomal miR-141 is upregulated in the serum from patients with PCa compared with patients with BPH or the healthy volunteers, and it may be a useful potential biomarker for the diagnosis of metastatic PCa.