Abstract 5251: Branching morphogenesis in the mammary gland is regulated by sprouty-2

Abstract Branching morphogenesis is a conserved mechanism used by many species for organogenesis and tissue maintenance. Receptor tyrosine kinases (RTKs), including the epidermal growth factor receptor (EGFR), and their intracellular regulators, the sprouty protein family is believed to be a critical regulator of branching morphogenesis. In this study, we show that, Sprouty-2 (Spry-2) is predominantly expressed in the luminal epithelial cells both in ducts and lobuli in the human breast gland. We have also analyzed the expression of Spry-2 and EGFR pathway in virgin, lactating and pregnant mouse mammary gland. Spry-2 is expressed at branching epithelial buds during pregnancy with increased expression during lactation. The expression of phosphorylated EGFR (Y1068) shows a similar expression pattern as Spry-2. Using D492 a breast epithelial cell line with stem cell properties, that generate branching structures in 3D laminin rich gel we show that Spry-2 expression increases during the formation of branching. Immunostaining locates expression of Spry-2 and active EGFR at the tip of lobular-like, branching ends. Interestingly, knocking down (KD) spry-2 expression using shRNA resulted in increased migration. Spry-2 knockdown also gives larger and more complex branching structures indicating loss of negative feedback control of branching morphogenesis. In co-culture with endothelial cells, D492 spry-2 KD cells generate predominantly spindle like colonies reminiscent of epithelial to mesenchymal tansition. In conclusion, these data indicate that Spry-2 is an important regulator of branching morphogenesis and dysregulation of sprouty expression can lead to aberrant development related to breast cancer, such as epithelial to mesenchymal transition in the mammary gland. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5251. doi:1538-7445.AM2012-5251