Identification of serum exosomal miR-148a as a novel prognostic biomarker for breast cancer

OBJECTIVE: Breast cancer (BC) is one of the most common malignancies affecting females. Aberrant expression of microRNAs (miRNAs) has been associated with carcinogenesis of BC. The aim of our study was to investigate the correlation of serum exosomal miR148a expression and the clinical outcome of patients with BC. PATIENTS AND METHODS: Quantitative Real Time-Reverse Transcription Polymerase Chain Reaction (qRT-PCR) was applied to evaluate the expression level of serum exosomal miR-148a in patients with BC, patients with benign breast tumors, and healthy controls. Then, the clinical value of serum exosomal miR-148a in BC was evaluated. RESULTS: Serum exosomal miR-148a levels were gradually downregulated from healthy controls patients with benign breast tumors to BC patients. Serum exosomal miR-148a could well distinguish BC patients from healthy volunteers. The expression level of serum exosomal miR-148a in BC patients was significantly upregulated following surgery, while dropped in the cases with disease relapse. A significant association was found between serum exosomal miR-148a levels and the tumor-node-metastasis (TNM) stage, differentiation, and lymph node metastasis in BC. In addition, BC patients with lower expression of serum exosomal miR-148a levels suffered worse overall survival and disease-free survival than those with higher expression of serum exosomal miR-148a levels. Furthermore, serum exosomal miR-148a was an independent risk factor for BC. CONCLUSIONS: Our data have demonstrated that serum exosomal miR-148a is significantly reduced in patients with BC and downregulation of serum exosomal miR-148a is closely associated with unfavorable clinical outcome of BC, indicating that serum exosomal miR-148a might serve as a promising diagnostic and prognostic biomarker for BC.