Estrogen Receptor Beta (ERβ) in Endometrial Simple Hyperplasia and Endometrioid Carcinoma

Abstract

The aim of this study was to analyze the expression of estrogen receptor (ER) beta in endometrioid carcinoma in comparison to non-neoplastic endometrium. Fifty-seven histopathologically confirmed non-neoplastic endometria (22 proliferative phase, 15 secretory phase, and 20 simple hyperplasia without atypia), and 26 cases of endometrioid carcinoma were studied. The ERbeta/ERalpha transcript ratio was determined by semiquantitative reverse transcription-polymerase chain reaction. The receptor protein expression was evaluated by immunohistochemistry using the Allred Scoring System. Decreased expression of ERbeta, ERalpha, and progesterone receptor proteins was observed in endometrioid carcinoma compared with proliferative endometrium and simple hyperplasia (P<0.01, Mann-Whitney U test). Within the group of endometrioid carcinoma, a correlation of increased ERbeta expression with tumors exhibiting > or =50% myoinvasion (P=0.034) was observed, whereas there was no correlation with the grade of tumor (P=0.314). There was a significant association of ERbeta with ERalpha expression in both non-neoplastic and neoplastic endometrium indicating interdependence of expression. Progesterone receptor protein expression was influenced by ERalpha levels and not by ERbeta as shown by regression analysis in non-neoplastic and neoplastic endometrium. Thus, ERbeta alterations are important in endometrioid carcinoma. The relationship of ERbeta expression to myoinvasion warrants further investigation.