Abstract
Breast cancer, the most prevalent cancer type among women worldwide, remains incurable once metastatic. Long noncoding RNA (lncRNA) and microRNA (miRNA) play important roles in breast cancer by regulating specific genes or proteins. In this study, we found miR-133b was silenced in breast cancer cell lines and in breast cancer tissues, which predicted poor prognosis in breast cancer patients. We also confirmed that lncRNA NEAT1 was up-regulated in breast cancer and inhibited the expression of miR-133b, and identified the mitochondrial protein translocase of inner mitochondrial membrane 17 homolog A (TIMM17A) that serves as the target of miR-133b. Both miR-133b knockdown and TIMM17A overexpression in breast cancer cells promoted cell migration and invasion both in vitro and in vivo. In summary, our findings reveal that miR-133b plays a critical role in breast cancer cell metastasis by targeting TIMM17A. These findings may provide new insights into novel molecular therapeutic targets for breast cancer.