Cyclosporin A promotes growth and invasiveness in vitro of human first-trimester trophoblast cells via MAPK3/MAPK1-mediated AP1 and Ca2+/calcineurin/NFAT signaling pathways

Cyclosporin A (CsA) has provided the pharmacologic foundation for organ transplantation as a calcineurin inhibitor blocking T-cell activation. We have demonstrated that CsA promoted trophoblast viability/proliferation and invasion in vitro. In the present study, we further investigated the intracellular signalling pathways involved in enhancing cell viability/proliferation and invasiveness of the human trophoblast induced by CsA. We showed that blocking mitogen-activated protein kinase 3 (MAPK3)/MAPK1 signaling by U0126 attenuated CsA-increased cell viability and invasiveness of trophoblasts. Cyclosprin A inhibited ionomycin-stimulated nuclear factor of activated T-cells (NFAT) transactivation in JAR cells and reversed the ionomycin-inhibited trophoblast invasiveness. However, either activating calcineurin by ionomycin, resulting in NFAT transactivation, or inhibiting NFAT using an NFAT inhibitor had no effect on trophoblast cell viability/proliferation and apoptosis in vitro. Hence, the CsA-induced promotion of trophoblast growth and invasion occurred by overlapping but independent pathways. The MAPK3/MAPK1 pathway was essential for both trophoblast growth and invasion, whereas the Ca2+/calcineurin/NFAT pathway was only involved in the CsA-promoted trophoblast invasiveness. Finally, potential crosstalk between MAPK3/MAPK1 and Ca2+/calcineurin/NFAT and its relationship to activator protein 1 activation was investigated. Our findings explored possible signal transduction pathways modulated by CsA, which may lead to the expansion of the clinical applications of this drug.