Prognostic and biological significance of microRNA-221 in breast cancer

Introduction: Breast cancer (BC) is the most notorious cancer between females with high rates of morbidity and mortality. The aim of this study was to determine the differential expression of breast tissues microRNA-221 (miR-221) and assess its prognostic and biological significance in breast cancer (BC).

Methods: A quantitative reverse transcription PCR (qPCR) assay was performed to detect the expression of breast tissue miR-221 in different subtypes of BC (n=76) and controls (n=36) and its correlations with clinicopathological factors of patients. Univariate and multivariate analyses using the Cox proportional hazards model were performed to analyze the prognostic significance of miR-221 expression.

Result: Our data indicated that the relative level of miR-221 expression in BC tissues was significantly higher than that in noncancerous breast tissues (p<0.01). Of 76 BC patients, 62 (81.6%) were positive cases. By statistical analyses, high miR-221 expression was observed to be closely correlated with advanced clinical stage (p<0.01). Moreover, patients with high miR-221 expression had worse 5-year relapse free survival (p=0.0124). Univariate and multivariate analyses indicated that high miR-221 expression was an independent poor prognostic factor for BC patients.

Conclusion: miR-221 is a potential biomarker for predicting the survival of BC patients and may be a molecular therapeutic target for BC.