Expression of estrogen receptor alpha and beta in peritoneal and ovarian endometriosis

Objective: To quantify and compare messenger RNA (mRNA) levels of ER-α and ER-β among ovarian endometriotic cysts and red and black peritoneal endometriotic lesions. Design: Prospective study. Setting: University hospital. Patient(s): Patients with or without endometriosis. Intervention(s): Samples of peritoneal (n = 33) and ovarian endometriotic lesions (n = 37) were obtained during laparoscopic surgery. Normal eutopic endometrial tissues and macroscopically normal peritoneal tissues were obtained as controls during or just after surgery. Main Outcome Measure(s): Expression of mRNA for ER-α and ER-β, using a real-time reverse transcription (RT)-PCR assay, TaqMan RT-PCR, and nonradioactive in situ hybridization (ISH) techniques. Result(s): Both eutopic endometrium and endometriotic tissues showed predominantly higher levels of ER-α than ER-β mRNA. Relative ratio of ER-α to ER-β (ER-α/ER-β) mRNA in red peritoneal lesions was significantly higher than in black lesions and ovarian endometriotic cysts. There was no significant difference in ER-α/ER-β between proliferative eutopic endometrium and red peritoneal lesions. These results were confirmed by ISH analysis, which also revealed that the two estrogen receptors were localized in both epithelial and stromal cells of endometriotic tissues. Conclusion(s): The predominant expression of ER-α in both glandular epithelial and stromal cells may be essential for the development and growth of peritoneal and ovarian endometriosis.