MicroRNA-137 inhibits BMP7 to enhance the epithelial-mesenchymal transition of breast cancer cells

// Xuexiang Ying 1 , Yunpo Sun 1 , Pingqing He 1 1 Department of General Surgery, Shanghai Jiaotong University Affiliated Sixth People's Hospital, 200233, China Correspondence to: Pingqing He, email: hpq345@yeah.net Keywords: breast cancer (BC), epithelial-mesenchymal transition (EMT), miR-137, bone morphogenetic protein-7 (BMP7) Received: December 06, 2016      Accepted: January 11, 2017      Published: February 17, 2017 ABSTRACT Bone morphogenetic protein-7 (BMP7) is known to antagonize transforming growth factor β 1 (TGFβ1)-mediated fibrosis through suppressing epithelial-mesenchymal transition (EMT). We recently reported that BMP7 also antagonizes the effects of TGFβ1 in breast cancer (BC) tumorigenesis-related EMT. Nevertheless, the control of BMP7 expression in BC remains ill-defined. Here, we detected significantly lower levels of BMP7 and significantly higher levels of microRNA-137 (miR-137) in the BC specimens, relative to paired adjacent non-tumor breast tissue. BMP7 and miR-137 levels were correlated inversely. Additionally, the high miR-137 levels in BC specimens were correlated with reduced patient survival. In vitro , overexpression of miR-137 significantly increased cell EMT and invasion, while depletion of miR-137 significantly decreased cell EMT and invasion in BC cells. The increases in BC cell invasiveness by miR-137 appeared to result from its suppression of BMP7, through direct binding of miR-137 to the 3'-UTR of BMP7 mRNA, thereby blocking its protein translation in BC cells. This study sheds light on miR-137 as a crucial factor that enhances BC cell EMT and invasiveness, and points to miR-137 as a promising innovative therapeutic target for BC treatment.