Gse1 coiled-coil protein (GSE1), also known as KIAA0182, is a proline rich protein. However, the function of GSE1 is largely unknown. In this study, we reported that GSE1 is overexpression in breast cancer and silencing of GSE1 significantly suppressed breast cancer cells proliferation, migration and invasion. Furthermore, GSE1 was identified as a direct target of miR-489-5p, which is significantly reduced in breast cancer tissues. In addition, forced expression of miR-489-5p suppressed breast cancer cells proliferation, migration and invasion. Moreover, depletion of GSE1 by siRNAs significantly abrogated the enhanced proliferation, migration and invasion of breast cancer cells consequent to miR-489-5p depletion. Taken together, these findings suggest that GSE1 may function as a novel oncogene in breast cancer and it can be regulated by miR-489-5p. (C) 2016 Elsevier Inc. All rights reserved.