Quantitative analysis of estrogen receptor alpha and beta messenger ribonucleic acid levels in normal endometrium and ovarian endometriotic cysts using a real-time reverse transcription-polymerase chain reaction assay

Abstract Objective: To quantify messenger RNA (mRNA) levels of the two estrogen receptor isoforms, estrogen receptor-α (ER-α) and estrogen receptor-β (ER-β) in the eutopic endometrium and ovarian endometriotic cysts. Design: Prospective study. Setting: University hospital. Patient(s): Patients with endometriosis and patients with uterine leiomyoma or carcinoma in situ. Intervention(s): Gonadotropin-releasing hormone agonist (GnRH-a)-treated (n = 12) or untreated (n = 24) endometriotic cysts were obtained from 36 patients during laparoscopic cystectomy. Eutopic endometrium tissues were obtained from 24 patients during or immediately after surgery. Main Outcome Measure(s): ER-α and ER-β mRNA levels, using a real-time reverse transcription (RT)-polymerase chain reaction (PCR) assay, TaqMan RT-PCR. Result(s): Eutopic endometrium and ovarian endometriotic cysts showed predominantly higher levels of ER-α mRNA than ER-β mRNA. Although ER-α and ER-β mRNA levels in the eutopic endometrium were affected by a cyclic change in ovarian hormones, ovarian endometriotic cysts were less affected. Moreover, a long-term hypoestrogenic state induced by GnRH-a especially decreased ER-α mRNA levels in endometriotic cysts. Consequently, the relative ratios of ER-α to ER-β mRNA levels in both GnRH-a-treated and untreated endometriotic cysts were significantly lower than those in the eutopic endometrium. Conclusion(s): The results suggest that the principal and regulatory effects of estrogens may be mediated mainly via ER-α rather than ER-β in both the eutopic endometrium and endometriotic cysts.