MicroRNA‑124 suppresses cell proliferation and invasion of triple negative breast cancer cells by targeting STAT3.

MicroRNAs (miRNAs) are pivotal regulators of the progression of carcinogenesis and negatively regulate the expression of tumour‑associated genes. Downregulation of miR‑124 expression has been demonstrated in various human cancer tissues, wherein miR‑124 serves as a tumour suppressor by targeting oncogenes. However, its function and underlying mechanism of action remain unclear in breast cancer. In the present study, the tissue‑specific expression of miR‑124 was detected in 10 paired triple‑negative breast cancer and normal tissues, and its inhibitory effects on cell growth and invasion were evaluated in vitro and in vivo. Bioinformatics analysis identified signal transducer and activator of transcription 3 (STAT3), a well‑known oncogene in breast cancer, as the potential target. Upregulation of miR‑124 expression decreased STAT3 mRNA and protein levels in breast cancer cells and the relative luciferase activity. Rescue experiments revealed that the transfection of a STAT3 expression plasmid reversed the inhibitory effect of miR‑124 on the proliferation and invasion of MDA‑MB‑468 cells. These data demonstrate that miR‑124 serves vital roles in the suppression of triple‑negative breast cancer via inhibition of cell proliferation and invasion through STAT3. These results highlight the potential role of miR‑124 as a diagnostic or therapeutic target in patients with breast cancer.