Expression patterns of microRNA-329 and its clinical performance in diagnosis and prognosis of breast cancer

: This study was aimed to assess the expression and clinical performance of microRNA-329 (miR-329) in breast cancer. We recruited 134 breast cancer patients and 70 healthy volunteers for this study. MiR-329 expression was estimated by quantitative real-time polymerase chain reaction. A receiver operating characteristic assay was performed to evaluate the diagnostic value of serum miR-329. In addition, the prognostic significance of miR-329 was evaluated through Kaplan-Meier survival and Cox regression analyses. According to quantitative real-time polymerase chain reaction, miR-329 expression was downregulated in cancerous samples compared with healthy and normal controls (P<0.01), and its expression in serum specimens positively correlated with its expression in tissue samples (R=0.493, P<0.001). The decreased expression of miR-329 correlated with lymph node metastasis (P=0.015) and TNM stage (P=0.003). A receiver operating characteristic curve with an area under the curve of 0.932 was constructed, indicating the high diagnostic accuracy of miR-329. From the survival and multivariate Cox assays, we found that downregulated miR-329 expression was associated with poor overall survival (log-rank P<0.001) and served as an independent prognostic factor (hazard ratio =2.987, 95% CI =1.681-5.308, and P<0.001). In silico analysis using The Cancer Genome Atlas confirmed that miR-329 expression was lower in breast cancer cases compared with normal controls (P<0.001) and could be an efficient biomarker for cancer patients. Down-regulated miR-329 expression was an effective diagnostic and prognostic biomarker, which could be used for targeted therapy in patients with breast cancer.