Evaluation of mRNA expression of estrogen receptor beta and its isoforms in human normal and neoplastic endometrium.

Endometrial cancer is well known to be estrogen-dependent. Two estrogen receptor types, ERalpha and ERbeta, are major mediators of a diversity of biologic functions of estrogen and play an important role in estrogen-dependent tissues and cancers. Cloning of ERbeta was followed by the discovery of a variety of its isoforms. Using real-time RT-PCR, the relative expression levels of ERbeta1, ERbeta2 (ERbetacx), ERbeta3, ERbeta4 and ERbeta5 were studied. We observed coexpression of ERbeta isoforms in the endometrium and upregulation of the ERbeta5 transcript in malignant endometrium. We also observed downregulation of ERbeta2Delta5 transcript in neoplastic endometrium, using a semiquantitative method. Our results suggest that analyzing the changes in ERbeta and its isoforms may be important in the diagnosis, prognosis and treatment of endometrial cancer.