Abstract
BACKGROUND: MicroRNAs (miRNAs) are involved in tumor progression of various human malignancies. MicroRNA-19b (miR-19b) has been described as serving a crucial role in tumorigenesis of breast cancer. The purpose of this study was to investigate the expression patterns, clinical value, and functional role of miR-19b in breast cancer. METHODS: Expression of miR-19b was estimated by quantitative real time PCR. Kaplan-Meier survival analysis and Cox regression assay were performed to explore the prognostic value of miR-19b. The functional role of miR-19b was verified using cell experiments. RESULTS: Upregulated miR-19b expression was observed in breast cancer tissues and cells compared with the controls (all P<0.05). The miR-19b expression was associated with distant metastasis and TNM stage. The survival curves showed that high miR-19b was correlated with poor overall survival of the patients (log-rank P=0.002). Furthermore, miR-19b was proven to be an independent prognostic factor for patients. By using miR-19b mimic and inhibitor, cell proliferation, migration, and invasion were enhanced by miR-19b overexpression but were suppressed by reduction of miR-19b (all P<0.05). Besides, PI3K/AKT was demonstrated to be activated by miR-19b in breast cancer cells. CONCLUSION: The overexpression of miR-19b serves as a candidate prognostic biomarker of breast cancer and may be involved in the tumor progression through PI3K/AKT pathway.