Targeting colony stimulating factor-1 receptor signalling to treat ectopic pregnancy.

1-2% of pregnancies are ectopic, the majority implanting in the Fallopian tube. A single, systemic dose of methotrexate, a DNA-synthesis (S phase) inhibitor, has been used since 1991 for outpatient treatment of women with stable EP. However, methotrexate has limited clinical and cost effectiveness, restricting its use to 25-30% of these women. There is an unmet need for better medical treatment for EP. Colony stimulating factor-1 (CSF-1) promotes placentation and creates a pro-inflammatory environment that is fundamental for the maintenance of a normal pregnancy. We hypothesised that CSF-1 is also involved in the placentation and maintenance of an EP. Herein, we demonstrate the immunolocalisation of the CSF-1 receptor (CSF-1R) as well as its ligand (CSF-1) in immortalised first trimester trophoblast cells. We show that a specific CSF-1R kinase inhibitor, GW2580, abolishes CSF-1 induced trophoblast cell proliferation and migration and can be cytotoxic. We then demonstrate the expression of CSF-1R and CSF-1 in the cytotrophoblast and syncytiotrophoblast within ectopic implantation sites from women with EP. Our data suggests that CSF-1 is involved in the survival and proliferation of trophoblast cells in EP. This suggests that pharmacological disruption of CSF-1/CSF-1R signaling axis could be the basis of a new therapeutic for EP.