Identification of miR-25-3p as a tumor biomarker: Regulation of cellular functions via TOB1 in breast cancer

Breast cancer is the most common cancer in women and is one of the three most common malignancies worldwide. Serum microRNAs (miRNAs/miRs) are ideal biomarkers for tumor diagnosis and prognosis due to their specific biological characteristics. In several different types of cancer, miRNAs are associated with cell migration and invasion. In the present study, miR-25-3p expression levels were detected in tissue and serum samples derived from patients with breast cancer, and the diagnostic and prognostic value of miR-25-3p in breast cancer was evaluated. Cellular function assays were performed to evaluate the role of miR-25-3p in breast cancer. Moreover, dual-luciferase reporter assays and western blotting were performed to investigate the target of miR-25-3p. miR-25-3p expression was upregulated in breast cancer tissue and serum samples compared with normal breast tissue and serum samples. Patients with breast cancer with high serum miR-25-3p levels were more likely to have lymph node metastasis compared with those with low serum miR-25-3p levels. The area under the curve for miR-25-3p in the diagnosis of breast cancer was 0.748, with 57.1% sensitivity and 95.0% specificity. Moreover, the Kaplan-Meier survival curves demonstrated that patients with breast cancer with a low expression of serum miR-25-3p had a higher overall survival rate compared with patients with a high serum miR-25-3p expression. miR-25-3p knockdown suppressed breast cancer cell proliferation and invasion, and transducer of ERBB2, 1 (TOB1) was identified as a potential target gene regulated by miR-25-3p. Therefore, the present study suggested that miR-25-3p regulated cellular functions via TOB1 in breast cancer; therefore, miR-25-3p may serve as a breast cancer biomarker.