Effects of aromatase inhibitors on proliferation and apoptosis in eutopic endometrial cell cultures from patients with endometriosis

Objective: To study the effect of letrozole (Let) and anastrozole (Anas) on apoptosis and cell proliferation in epithelial endometrial cells (EEC) from patients with endometrosis (EDT). Design: Prospective study. Setting: Research institute and clinical fertility center. Patient(s): Eighteen women with untreated EDT. Intervention(s): Biopsy specimens of eutopic endometrium were obtained from all subjects. Apoptosis and cell proliferation were examined in EEC after incubation with Let or Anas. Main Outcome Measure(s): Percentage of apoptotic cells (ApC) was evaluated by the acridine orange-ethidium bromide technique; cell proliferation was assessed by H-3-Thymidine incorporation. Result(s): Treatment with Let 10 nM or Let 100 nM enhanced values of ApC in cultures from EDT patients. Epithelial endometrial cells treated with Anas 100nM or Anas 500 nM showed a statistically significant induction on apoptosis levels. Cultures treated with Let 1 nM or Anas 50 nM did not show any significant differences in ApC levels compared with basal conditions. H-3-Thymidine uptake was down regulated by Let 10 nM and Let 100 nM. Similarity, Anas 100 nM and Anas 500 nM showed a significantly lower degree of cell proliferation in EEC. Lower concentrations of Let and Anas did not induce any significant change in cell proliferation rates. Conclusion(s): Our results show that Let and Anas produced a significant and positive effect on apoptosis and cell proliferation on EEC from EDT patients. These findings support the further investigation of aromatase inhibitors as a treatment option in EDT.