Focal Adhesion Kinase-Mediated Sequences, Including Cell Adhesion, Inflammatory Response, and Fibrosis, as a Therapeutic Target in Endometriosis

Endometriosis has several distinguishing features in the ectopic endometrium, including chronic inflammation and fibrosis. According to the retrograde menstruation theory, endometriotic cells are derived from eutopic endometrial cells, and adhesion of endometrial cells to the extracellular matrix can be the initial step in the development of endometriosis. Therefore, we hypothesized that cell adhesion, which mediates a sequence of events in the development of endometriosis triggering inflammatory responses and tissue fibrosis could be a possible therapeutic target for endometriosis. We found co-upregulation of focal adhesion kinase (FAK) and monocyte chemoattractant protein-1 (MCP-1) in the endometriotic tissues compared with that in the normal endometrium. MCP-1 secretion was significantly higher in the endometriotic stromal cells than in the eutopic endometrial stromal cells. Furthermore, co-culture of U937 cells and endometriotic stromal cells upregulated secretion of transforming growth factor-β1 (TGF-β1). A FAK inhibitor significantly inhibited the secretion of MCP-1 in the endometriotic stromal cells and TGF-β1 in the co-culture with macrophages. FAK inhibitor treatment in the murine endometriosis model demonstrated a decrease in the formation of endometriotic lesions as well as the expression of MCP-1 and TGF-β1. Our results suggest that the FAK-mediated sequential development of endometriosis, including inflammatory response and tissue fibrosis, can be a new therapeutic target in endometriosis.