Endothelial Calcineurin Signaling Restrains Metastatic Outgrowth by Regulating Bmp2

Summary: Calcineurin/NFAT signaling is active in endothelial cells and is proposed to be an essential component of the tumor angiogenic response. Here, we investigated the role of endothelial calcineurin signaling in vivo in physiological and pathological angiogenesis and tumor metastasis. We show that this pathway is dispensable for retinal and tumor angiogenesis, but it is implicated in vessel stabilization. While ablation of endothelial calcineurin does not affect the progression of primary tumors or tumor cell extravasation, it does potentiate the outgrowth of lung metastases. We identify Bmp2 as a downstream target of the calcineurin/NFAT pathway in lung endothelium, potently inhibiting cancer cell growth by stimulating differentiation. We reveal a dual role of calcineurin/NFAT signaling in vascular regression or stabilization and in the tissue-specific production of an angiocrine factor restraining cancer cell outgrowth. Our results suggest that, besides targeting the immune system, post-transplantation immunosuppressive therapy with calcineurin inhibitors directly targets the endothelium, contributing to aggressive cancer progression. : Hendrikx et al. show that endothelial calcineurin signaling is dispensable for physiological and tumor angiogenesis. Instead, it promotes vascular stabilization and, in cancer, restrains metastatic outgrowth. Immunosuppressive therapy with calcineurin inhibitors thus also directly affects the endothelium, which may contribute to aggressive cancer progression in organ transplant recipients. Keywords: angiogenesis, calcineurin, NFAT, BMP2, endothelial, metastasis, melanoma