Activated Platelets Induce Estrogen Receptor β Expression in Endometriotic Stromal Cells

BACKGROUND/AIMS: Endometriosis is viewed first and foremost as an estrogen-dependent disease, featuring not only excessive estrogen production but also aberrant expression of estrogen receptors (ERs), particularly ERβ, that mediate the estrogen action. ERβ is the predominant ER in mediating estrogen action in endometriosis, and estrogen plays a vital role in the development of endometriosis; thus, ERβ is viewed as a strong candidate for therapeutic targeting. Given our recent finding that platelets aggregate in endometriotic lesions, we sought to investigate whether activated platelets can upregulate ERβ. METHODS: Using primary endometriotic stromal cells derived from patients with ovarian endometriomas and platelets harvested from healthy donors, we performed real-time RT-PCR analysis of mRNA abundance (n = 8) and Western blot analysis of protein expression (n = 8) of ERα and ERβ when co-cultured with phosphate-buffered saline, platelets, thrombin alone, and platelets plus thrombin for 48 h. RESULTS: Treatment of endometriotic stromal cells with activated platelets resulted in the upregulation of ERβ gene and protein expression. CONCLUSION: In the presence of aggregated and thus activated platelets in endometriotic lesions, ERβ, but not ERα, is upregulated in endometriotic stromal cells. Our result suggests that the use of antiplatelet therapy may have potential in the treatment of endometriosis.