Serum microRNA-21 expression as a prognostic and therapeutic biomarker for breast cancer patients

MiRNA-21 is recognized as the main active candidate and high expression in many solid tumors consequential cell proliferation, differentiation, apoptosis, and closely related to metastasis of disease. The study aimed to evaluate the serum miRNA-21 expression and therapy outcome in breast cancer patients and cell lines. Seventy-five histopathologically confirmed newly diagnosed breast cancer patients were included in the study; before and after therapy, patient's blood sample were collected and analyzed for serum microRNA-21 expression by quantitative real-time PCR. In patients, 8.9 mean fold increased microRNA-21 expression was observed compared to controls. Increased expression was found to be associated with advanced stage (11.72-fold), lymph node involvement (11.12-fold), and distant metastases (20.17-fold). After treatment significant decrease in miRNA-21 expression was observed and found to be significant (p < 0.0001). Patients treated with neoadjuvant therapy had significant impact on miRNA-21 suppression and found to be significantly associated with different clinicopathological features of patients. Increased miRNA-21 expression was also found to be significantly associated with poor survival of breast cancer patients (p = 0.002). MicroRNA-21 expression could be used as promising predictive indicators for breast cancer prognosis. MicroRNA-21 over-expression was associated with response to neoadjuvant therapy and may perhaps be considered as primary treatment choice.