Estrogen receptor β regulates endometriotic cell survival through serum and glucocorticoid-regulated kinase activation

Objective To determine the expression and biological roles of serum and glucocorticoid-regulated kinase (SGK1) in tissues and cells from patients with endometriosis and from healthy control subjects. Design Case-control. Setting University research setting. Patient(s) Premenopausal women. Intervention(s) Endometriotic tissues were obtained from women with ovarian endometriosis, and normal endometrial tissues were obtained from women undergoing hysterectomy for benign conditions. Main Outcome Measure(s) Expression levels of SGK1, the role of SGK1 in endometriosis pathology, and regulation of SGK1 by estrogen receptor (ER) β. Result(s) Transcript and protein levels of SGK1 were significantly higher in endometriotic tissues and cells compared with normal endometrium. SGK1 mRNA and protein levels were stimulated by E2, by the ERβ-selective agonist diarylpropionitrile, and by prostaglandin E2. SGK1 was transcriptionally regulated by ERβ based on small interfering RNA knockdown and chromatin immunoprecipitation of ERβ followed by quantitative polymerase chain reaction. SGK1 knockdown led to increased cleavage of poly(ADP-ribose) polymerase, and SGK1 activation was correlated with the phosphorylation of FOXO3a, a proapoptotic factor. Conclusion(s) ERβ leads to SGK1 overexpression in endometriosis, which contributes to the survival of endometriotic lesions through inhibition of apoptosis.