Platelet PI3Kβ regulates breast cancer metastasis

Platelets promote tumor metastasis by several mechanisms. Platelet-tumor cell interactions induce the release of platelet cytokines, chemokines, and other factors that promote tumor cell epithelial-mesenchymal transition and invasion, granulocyte recruitment to circulating tumor cells (CTCs), and adhesion of CTCs to the endothelium, assisting in their extravasation at metastatic sites. Previous studies have shown that platelet activation in the context of thrombus formation requires the Class IA PI 3-kinase PI3Kβ. We now define a role for platelet PI3Kβ in breast cancer metastasis. Platelet PI3Kβ is essential for platelet-stimulated tumor cell invasion through Matrigel. Consistent with this finding,