Estrogen receptor expression affected by hypoxia inducible factor-1α in stromal cells from patients with endometriosis

Objective: Endometriosis is an estrogen-dependent disease. The aim of this study was to evaluate the different expression of estrogen receptors (ER) and its relation to hypoxia inducible factor-1α (HIF-1α) in stromal cells from women with endometriosis. Materials and Methods: Paired eutopic endometrial and ectopic endometriotic stromal cells were isolated from women with endometriosis while they underwent laparoscopy. The expression of ERα and ERβ was measured by reverse transcription-polymerase chain reaction and Western blot. Regulation of ER expression was evaluated by HIF-1α knockdown via short interference RNA. Results: The expression of ERβ was significantly increased in ectopic stromal cells. Treatment of endometrial stromal cells with hypoxia induced ERβ expression. Knockdown of HIF-1α abolished hypoxia-induced ERβ expression and increased ERα expression. Conclusion: The expression of ERβ is regulated by hypoxia. Results of this study will provide important information in the involvement of hypoxia factors in mediating estrogen action via different ER expression in endometriosis.