Pihong Li, Jianda Dong, Xiang Zhou, Weijian Sun, He Huang, Tong Chen, Bing Ye, Zhiqiang Zheng, Mingdong Lu

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.