Smad6 determines BMP-regulated invasive behaviour of breast cancer cells in a zebrafish xenograft model

• Published in: Scientific reports 2016-04, Vol.6 (1), p.24968-24968, Article 24968
• Main Authors: de Boeck, Miriam, Cui, Chao, Mulder, Aat A, Jost, Carolina R, Ikeno, Souichi, ten Dijke, Peter
• Format: Article
• Language: English
• Subjects: 13; 13/95; 14; 14/19; 14/28; 14/35; 38; 38/1; 38/77; 59; 631/45/127/1219; 631/80/84/2336; 64; 64/116; 82; 82/29; 96; 96/21; Animals; Bone morphogenetic protein 6; Bone Morphogenetic Proteins - metabolism; Breast cancer; Breast Neoplasms - genetics; Breast Neoplasms - metabolism; Cell adhesion; Cell Line, Tumor; Cell Movement; Coculture Techniques; Electron microscopy; Endothelial cells; Female; Gene Expression Regulation, Neoplastic; Humanities and Social Sciences; Humans; Invasiveness; Mesenchyme; Metastases; Microvasculature; multidisciplinary; Neoplasm Invasiveness; Neoplasm Transplantation; Receptors, Estrogen - metabolism; Science; Signal Transduction; Smad protein; Smad6 Protein - genetics; Smad6 Protein - metabolism; Survival Analysis; Transforming growth factor; Transforming growth factor-b; Up-Regulation; Xenografts; Zebrafish
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep24968

The transforming growth factor-β (TGF-β) family is known to play critical roles in cancer progression. While the dual role of TGF-β is well described, the function of bone morphogenetic proteins (BMPs) is unclear. In this study, we established the involvement of Smad6, a BMP-specific inhibitory Smad, in breast cancer cell invasion. We show that stable overexpression of Smad6 in breast cancer MCF10A M2 cells inhibits BMP signalling, thereby mitigating BMP6-induced suppression of mesenchymal marker expression. Using a zebrafish xenograft model, we demonstrate that overexpression of Smad6 potentiates invasion of MCF10A M2 cells and enhances the aggressiveness of breast cancer MDA-MB-231 cells in vivo , whereas a reversed phenotype is observed after Smad6 knockdown. Interestingly, BMP6 pre-treatment of MDA-MB-231 cells induced cluster formation at the invasive site in the zebrafish. BMP6 also stimulated cluster formation of MDA-MB-231 cells co-cultured on Human Microvascular Endothelial Cells (HMEC)-1 in vitro . Electron microscopy illustrated an induction of cell-cell contact by BMP6. The clinical relevance of our findings is highlighted by a correlation of high Smad6 expression with poor distant metastasis free survival in ER-negative cancer patients. Collectively, our data strongly indicates the involvement of Smad6 and BMP signalling in breast cancer cell invasion in vivo .