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DOWNREGULATION OF FGFBP1 DURING EPITHELIAL TO MESENCHYMAL TRANSITION
Breast cancer is a disease that impacts nearly one out of three women at some point in their life. Although the scientific community’s understanding of breast cancer development is actively researched, there is still a low 5-year survival rate of 30% following distant metastasis compared to the near 100% survival rate for localized disease. Epithelial to mesenchymal transition (EMT) is a known contributor to metastasis. Cells that undergo EMT shed cell-to-cell junctions and become fibroblastic like cells with differential extracellular matrix organization and increased mesenchymal gene expression. This change allows for greater cell motility and invasive potential, critical for metastasis. Our recent studies with single cell RNA sequencing demonstrate distinct populations of epithelial and mesenchymal cells. Several components of fibroblast growth factor receptor (FGFR) signaling are regulated during EMT. Fibroblast growth factor binding protein 1 (FGFBP1) is a known developmental factor that was observed at low expression in mesenchymal cells, with an unknown role in breast cancer. This study utilizes immunoblotting, mRNA analyses, immunofluorescence staining and novel 3D culture platform to investigate the regulation of FGFBP1 during EMT. FGFBP1 was consistently downregulated in HER2 transformed human mammary epithelial cells (HME2) during transforming growth factor β (TGF-Beta) induced EMT. Since FGFBP1 is acts as a secretory chaperone protein, secretion rate analysis was conducted at time periods throughout EMT showing rapid downregulation of secretion. Characterization of FGFBP1 regulation during EMT could lead to greater understanding of EMT and possibly a more sensitive marker for EMT relative to the current known markers.