RESUMEN
MicroRNAs (miRNAs) play an important role in the regulation of human cancers, including breast cancer (BC). In the current study, we examined the expression pattern of the miRNA miR-125a-5p in human BC tissues, tumorigenesis of BC progression. We found that miR-125a-5p was significantly downregulated in human BC tissues. Overexpression of miR-125a-5p in a xenograft mouse model indicated that miR-125a-5p may function as a tumour suppressor during carcinogenesis. To explore the molecular mechanism by which miR-125a-5p contributes to BC progression, we predicted the target genes of miR-125a-5p and identified BC susceptibility gene 1-associated protein 1 (BAP1) as a direct target. Finally, we demonstrated that BAP1 had opposing effects to those of miR-125a-5p on BC cells, suggesting that miR-125a-5p may inhibit cell proliferation and promote cell apoptosis by negatively regulating BAP1. Taken together, our findings provide the first clues regarding the role of miR-125a-5p as a tumour suppressor in BC via the inhibition of BAP1 translation.