Background: The biological role of exosomes has attracted widespread attention in various fields of biomedicine. Exosome-delivered microRNAs (miRNAs) play crucial roles in cancer diagnosis. The aim of our study was to examine whether serum exosomal miR-17-5p could be identified as a diagnostic biomarker for breast cancer (BC). Methods: Eighty-three patients diagnosed with BC and thirty-four healthy women (controls) were included in this study. The expression level of serum exosomal miR-17-5p was identified by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and calculated by 2–ΔΔCq method.
Results: Reduced level of exosomal miR-17-5p in serum from BC patients was found compared with healthy controls. In addition, miR-17-5p also had low expression in 34 pairs of tissue and serum samples. MiR-17-5p was highly concentrated in serum exosomes and the expression level was stable. In addition, the exosomal miR-17-5p could distinguish BC from healthy controls with the area under the ROC curve (AUC) of 0.784 (p < 0.0001, sensi¬tivity = 66.67%, specificity = 83.95%). The sensitivity and specificity of miR-17-5p were superior to conventional se¬rum biomarkers CEA, CA125, and CA153. We predicted target genes of miR-17-5p were also mainly involved in cancer-related pathways.
Conclusions: In conclusion, our findings strongly suggested that serum exosomal miR-17-5p could serve as a novel diagnostic biomarker for BC.