RESUMO
BACKGROUND: Breast cancer remains one of the top threats to women's health. The current lack of tumor markers with desirable sensitivity and specificity is a major obstacle toward the future management of breast cancer. Many studies are directed to reveal the diagnostic and prognostic potentials of circulating miRNAs in breast cancer. In this study, we attempt to evaluate the feasibility and clinical utility of circulating miRNA-21 and let-7 as prognostic biomarkers for breast cancer. METHODS: Real-time quantitative polymerase chain reaction technique was used. Levels of miRNA-21 and let-7 expression were determined in sera from 125 participants representing 3 different groups. With fold-change analysis, the expression of miRNA-21 and let-7 in the decided groups were assessed. RESULTS: Patients with breast cancer showed significantly higher expression of miRNA-21 compared with controls and other participants with benign breast lesions (P < .001). The mean expression levels of serum miRNA-21 was 3.27 ± 2.10-fold in patients with breast cancer. The expression of miRNA let-7 was significantly decreased in patients with breast cancer (2.45 ± 2.20-fold) than the control group and the benign breast lesions group (5.27 ± 3.30-fold and 6.22 ± 4.90-fold, respectively; P < .001). Levels of miRNA let-7 expression negatively correlated with development of metastases in patients with breast cancer (P < .001). CONCLUSIONS: Our study establishes the association between altered levels of miRNA let-7 and metastases risk in patients with breast cancer, implying a role of miRNA let-7 in disease progression and prognosis.