Catecholestradiol Activation of Adrenergic Receptors Induces Endometrial Cell Survival via p38 MAPK Signaling.

CONTEXT: Enhanced levels of catecholestradiols, 2-hydroxyestradiol (2-OHE2) or 4-hydroxyestradiol (4-OHE2), are reported in endometriosis. During gestation, catecholestradiol activation of adrenergic receptors (AR) elevates estrogen receptor (ER)-independent proliferation of uterine arterial endothelial cells. OBJECTIVE: To investigate ß-AR-mediated catecholestradiol effects on human endometrial stromal cell (HESC) and epithelial cell survival in endometriosis. DESIGN: ß-AR immunostaining of eutopic and ectopic endometria (n = 9). Assays for cell viability, 5-bromo-2'-deoxyuridine proliferation, apoptosis, quantitative PCR, and estrogenicity (alkaline phosphatase activity), as well as siRNA ß-AR silencing and immunoblot analyses of cultured HESCs or Ishikawa cells treated with control or 2-OHE2 or 4-OHE2 ±ß-AR antagonist or ±p38 MAPK inhibitor. SETTING: University research institution. PATIENTS: Women with or without endometriosis. INTERVENTIONS: None. MAIN OUTCOME MEASURES: ß-AR expression in eutopic vs ectopic endometria and regulation of HESC survival by 2-OHE2 and 4-OHE2. RESULTS: Eutopic and ectopic endometrial stromal and epithelial cells displayed ß2-AR immunoreactivity with increased staining in the functionalis vs basalis layer (P < 0.05). Both 2-OHE2 and 4-OHE2 enhanced HESC and Ishikawa cell survival (P < 0.05), an effect abrogated by ß-AR antagonist propranolol, but not ER antagonist ICI182,780. 2-OHE2 or 4-OHE2 failed to induce cell survival and estrogenic activity in ADRB2-silenced HESCs and in Ishikawa cells, respectively. Although 2-OHE2 inhibited apoptosis and BAX mRNA expression, 4-OHE2 induced proliferation and decreased apoptosis (P < 0.05). Both catecholestradiols elevated phospho-p38 MAPK levels (P < 0.05), which was blocked by propranolol, and p38 MAPK inhibitor reversed catecholestradiol-enhanced HESC survival. CONCLUSIONS: Catecholestradiols increase endometrial cell survival by an ER-independent ß-AR-mediated p38 MAPK activation, suggesting that agents blocking ß-AR (e.g., propranolol) or inhibiting 2-OHE2- or 4-OHE2-generating enzymes (i.e., CYP1A1/B1) could treat endometriosis.