Dienogest increases the progesterone receptor isoform B/A ratio in patients with ovarian endometriosis

Background: The resistance of endometriotic tissue to progesterone can be explained by alterations in the distribution of progesterone receptor (PR) and estrogen receptor (ER) isoforms. The aims of this study were to examine the expressions of PR-A, PR-B, ER alpha and ER beta in endometrioma and assess whether these expressions are affected by dienogest or leuprolide acetate (LA) treatment. Methods: We enrolled 60 females, including 43 patients with endometriosis (14 who received no medical treatment, 13 who received dienogest and 16 who received LA before undergoing laparoscopic surgery) and 17 patients with leiomyoma. The expression levels of PR and ER isoforms in eutopic and ectopic endometrium were assayed with quantitative real-time PCR, and confirmed with immunohistochemistry. Results: A decreased PR-B/PR-A ratio and an increased ER beta/ER alpha ratio were demonstrated in ectopic endometrium derived from females with endometriosis compared with the ratios observed in eutopic endometrium obtained from females without endometriosis. Although LA treatment did not affect the PR-B/PR-A and ER beta/ER alpha ratios, dienogest treatment increased the PR-B/PR-A ratio and decreased the ER beta/ER alpha ratio in patients with endometriomas. Conclusions: Dienogest may improve progesterone resistance in endometriotic tissue by increasing the relative expressions of PR-B and PR-A, and decreasing the relative expressions of ER beta and ER alpha.