Gremlin-1 Promotes Metastasis of Breast Cancer Cells by Activating STAT3-MMP13 Signaling Pathway

Gremlin-1 (GREM1), one of the bone morphogenetic protein (BMP) antagonists, can directly bind to BMPs. GREM1 is involved in organogenesis, tissue differentiation, and organ fibrosis. Recently, numerous studies have reported the oncogenic role of GREM1 in cancer. However, the role of GREM1 in metastasis of breast cancer cells and its underlying mechanisms remain poorly understood. The role of GREM1 in breast cancer progression was assessed by measuring growth, migration, and invasion of breast cancer cells. An orthotopic breast cancer mouse model was used to investigate the role of GREM1 in lung metastasis of breast cancer cells. GREM1 knockdown suppressed the proliferation of breast cancer cells, while its overexpression increased their growth, migration, and invasion. Cells with Grem1-knockdown showed much lower tumor growth rates and lung metastasis than control cells. GREM1 enhanced the expression of matrix metalloproteinase 13 (MMP13). A positive correlation between GREM1 and MMP13 expression was observed in breast cancer patients. GREM1 activated signal transducer and activator of transcription 3 (STAT3) transcription factor involved in the expression of MMP13. Our study suggests that GREM1 can promote lung metastasis of breast cancer cells through the STAT3-MMP13 pathway. In addition, GREM1 might be a promising therapeutic target for breast cancer metastasis.