Estrogen up-regulates cyclooxygenase-2 via estrogen receptor in human uterine microvascular endothelial cells

Objective To investigate the effects of 17β-estradiol (E₂) on cyclooxygenase-2 (COX-2) expression and prostaglandin E₂ (PGE ₂) synthesis in primary human uterine microvascular endothelial cells (HUMEC). Design Prospective study. Setting Basic research laboratory at an academic medical center. Patient(s) Primary HUMEC of three women donors and primary human dermal microvascular endothelial cells of three women donors (as control), purchased from a third-party source. Intervention(s) The HUMEC were cultured in specific media in a humidified atmosphere with 5% CO₂ at 37°C. Main outcome measure(s) Measures of COX-2 mRNA and protein, PGE ₂ production, and estrogen receptor α and β mRNA and protein. Result(s) Treatment with E₂ (10^-10 to 10 ^-6 M) increased COX-2 mRNA levels by 2.3-fold to 2.4-fold in HUMEC. Treatment of HUMEC with E₂ (10^-8 M) resulted in a time-dependent increase of COX-2 mRNA levels. This was accompanied by a 2.8-fold increase in COX-2 protein level and a 1.5-fold increase in PGE₂ synthesis. Pretreatment of HUMEC with a selective COX-2 inhibitor, NS-398, abolished E₂-induced PGE₂ synthesis, suggesting that E₂ specifically up-regulates COX-2 activity. The estrogen receptor antagonist ICI 182,780 fully reversed the stimulation of COX-2 mRNA and protein levels and PGE₂ synthesis by E₂. Interestingly, estrogen receptor β mRNA and protein were abundant in HUMEC, whereas estrogen receptor α mRNA or protein was barely detectable. Conclusion(s) We conclude that various levels of E₂ can significantly increase COX-2 expression and PGE₂ synthesis in HUMEC via the estrogen receptor.