Abstract

The tumor microenvironment and wound healing after injury both contain extremely high concentrations of the extracellular signaling molecule, adenosine triphosphate (ATP) compared to normal tissue. P2Y2 receptor, an ATP-activated purinergic receptor, is typically associated with pulmonary, endothelial, and neurological cell signaling. Here we report its role and importance in breast epithelial cell signaling and how it is altered in metastatic breast cancer. In response to ATP activation, P2Y2 receptor signaling causes an increase of intracellular Ca2+ in non-tumorigenic breast epithelial cells, while their tumorigenic and metastatic counterparts have significantly reduced Ca2+ responses. The non-tumorigenic cells respond to increased Ca2+ with actin polymerization and localization to cell edges, while the metastatic cells remained unaffected. The increase in intracellular Ca2+ after ATP stimulation was blunted using a P2Y2 antagonist, which also prevented actin mobilization and caused cell dissemination from spheroids in non-tumorigenic breast epithelial cells. Furthermore, the lack of Ca2+ concentration changes and actin mobilization in the metastatic breast cancer cells could be due to reduced P2Y2 expression, which correlates with poorer overall survival in breast cancer patients. This study elucidates rapid changes that occur after elevated intracellular Ca2+ in breast epithelial cells and how metastatic cancer cells have adapted to evade this cellular response.