Bovine lactoferrin suppresses the proliferation of endometriotic stromal cells via the PI3K/Akt/mTOR pathway

The most common medical therapy for endometriosis suppresses ovulation, which is a barrier for patients planning pregnancy. To address this issue, we focused on the cell proliferation-suppressing effects of lactoferrin, which reportedly in various malignant tumours. Despite being a benign disease, endometriotic cells have similar characteristics to malignant tumours, which may be involved in its onset and progression. Endometriotic and endometrial stromal cells were obtained from patients with endometriosis. After culture with 1 mg/mL of bovine lactoferrin, cell proliferation was significantly suppressed in endometriotic stromal cells compared to controls, but this remained unchanged in endometrial stromal cells. Bovine lactoferrin also significantly increased the number of endometriotic stromal cells in the G0/G1 phase and significantly decreased those in the S phase, and suppressed the protein expression of phosphorylated-AKT, phosphorylated-mTOR, phosphorylated-S6K, and cyclin D1. Bovine lactoferrin inhibits the transition from the G1 to the S phase by suppressing the PI3K/Akt/mTOR pathway and reducing the synthesis of cyclin D1, thereby arresting the cell cycle at the G1 phase. Bovine lactoferrin suppressed the proliferation of endometriotic stromal cells without suppressing the proliferation of endometrial stromal cells. Lactoferrin, which allows for pregnancy and lactation during administration, has potential as a novel therapeutic candidate for endometriosis.