Breast cancer stem cells (BCSCs) constitute a subpopulation of tumor cells that express stem cell associated markers and have a high capacity for tumor generation in vivo. MicroRNAs (miRNAs) are involved in tumorigenesis by regulating specific oncogenes and tumor suppressor genes, and their roles in BCSCs are becoming more apparent. We try to reveal the mechanism by which specific miRNA plays its function in BCSCs. Herein, we show that miR-130a-3p is down-regulated in human breast cancer tissues and exosomes from circulating blood. Overexpression of miR-130a-3p in BCSCs inhibited cellular proliferation, migration, and invasion, and silencing of miR-130a-3p had the opposite effects. We also confirmed that RAB5B is directly down-regulated by miR-130a-3p. Knockdown of RAB5B also inhibited cell proliferation, migration and invasion. Furthermore, we found that lower levels of exosome-derived miR-130a-3p are associated with lymph node metastasis and advanced TNM stage. Taken together, our results demonstrate that miR-130a-3p may act as a disease progression monitoring indicator and therapeutic target in breast cancer. (C) 2018 Elsevier Inc. All rights reserved.