Expression of estrogen α and β variants, androgen, and progesterone receptors in human normal and neoplastic endometrium

The recent cloning of the estrogen receptor beta (ERP) has been followed by the discovery of a variety of its isoforms. Since endometrial cancer (ECA) is an estrogen-dependent cancer, an analysis of its expression of ERalpha and ERP isoforms may contribute to our understanding of the mechanism of its development. Using the real-time RT-PCR assay, the quantitative expression of ERalpha, ERbeta1, ERbeta2 (Pcx), ERbeta3, ERbeta4, and ERbeta5, as well as androgen (AR) and progesterone receptors (PR) was determined and compared in normal and neoplastic endometrium. Our data demonstrates the co-expression of all the ERP isoforms in the normal endometrium, and an up-regulation of the ERbeta5 transcript in malignant endometrium. A decrease in the levels of AR mRNA between normal and neoplastic endometrium, was also noted. With respect to clinical parameters, the decreased expression of PR mRNA correlates inversely with endometrium tumor grade. The expression profiles of ERa and AR were different between pre and postmenopausal endometrium, with a significant increase during menopause.