Down-regulation of Bcl-2 is a potential marker of the efficacy of progestin therapy in the treatment of endometrial hyperplasia

Objective. The objective of this study was to evaluate the expression of bcl-2, a regulatory protein in programmed cell death, in endometrial hyperplasia before and after progestational therapy. Methods. Pre- and posttreatment paraffin-embedded endometrial tissue samples from 20 women with an initial diagnosis of endometrial hyperplasia were obtained from archived files. Cases were evaluated and classified as either complete resolution of hyperplasia or persistent hyperplasia in response to progestin treatment. Sections were examined for bcl-2, estrogen receptor, and progesterone receptor expression using immunohistochemistry and compared within the treatment response groups. Results. Among the 20 women studied, 13 had complete regression of their hyperplasia with progestin treatment and 7 had evidence of persistent disease after therapy. Bcl-2 expression was significantly decreased after treatment from a mean reactivity score of 2.08 to 0.31 (P = 0.0005) in the group of patients whose hyperplasia completely regressed with progestin administration. Among the women who had persistent hyperplasia after therapy, no significant change was observed between pre- and posttreatment bcl-2 expression, with a mean reactivity of 1.86 to 1.29, respectively (P = 0.075). Progestational therapy significantly decreased the status of estrogen receptors from a mean score of 2.08 to 0.46 (P = 0.0005) in completely resolved cases of hyperplasia and from 2.00 to 0.43 (P = 0.0025) in persistent hyperplasias. Treatment also significantly decreased the status of progesterone receptors from a mean reactivity score of 1.92 to 0.31 (P = 0.0005) in cases of regressed hyperplasia and from a mean reactivity of 1.86 to 0.29 (P = 0.005) in persistent cases of hyperplasia. Conclusions. Bcl-2 expression decreases following successful progestin treatment of endometrial hyperplasias, whereas it remains expressed in hyperplasias which persist despite progestational therapy. This suggests that bcl-2 expression may represent a component of the therapeutic effects exerted in the endometium during progestational therapy in the treatment of hyperplasia. The activity of the oncoprotein may be a potential measure of the progress of treatment.