Plasma extracellular vesicle-packaged microRNAs as candidate diagnostic biomarkers for early-stage breast cancer

Extracellular vesicle-packaged microRNAs (miRNAs) are a class of circulating miRNAs located in the plasma that are packaged into extracellular vesicles. The present study examined the expression profiles of extracellular vesicles and tissue miRNAs with the aim of investigating the miRNA signatures in early-stage breast cancer. The present study identified and compared the extracellular vesicle-packaged miRNA expression signature and tissue miRNA expression signature from healthy individuals (n=10) and patients with early-stage breast cancer (n=12). A total of five miRNAs, including miRNA-375, miRNA-24-2-5p, miRNA-548b-5p, miRNA-655-3P and miRNA-376b-5p, were synchronized in extracellular vesicles and tissues of the breast cancer group when compared with the healthy group. The highest area under the curve (AUC) for a single miRNA was achieved with miRNA-548b-5p [AUC=0.785; 95% confidence interval (CI)=0.585–0.984; P=0.022]. The highest overall AUC was achieved by the combination of miRNA-375, miRNA-655-3p, miRNA-548b-5p and miRNA-24-2-5p (AUC=0.808; 95% CI=0.629–0.986; P=0.013). The Kaplan-Meier curves and log test analysis results of these five miRNAs, especially those for miRNA-548b-5p, were partly consistent with the hypothesis. Two miRNAs (miRNA-548b-5p and miRNA-376b-5p) were positively associated with patient survival, while two miRNAs (miRNA-375 and miRNA-24-2-5p) were negatively associated with patient survival. The present study provided a set of plasma extracellular vesicle-packaged miRNA-based biomarkers for the diagnosis of early-stage breast cancer.