Absence of estrogen receptor-β expression in metastatic ovarian cancer

Objective: To evaluate the expression of estrogen receptor (ER)alpha and ER beta mRNA and protein in normal ovarian tissue and primary and metastatic tumors. Methods: Estrogen receptor or and ER beta expression was studied in normal ovarian biopsies (n = 9) and primary (n = 8) and metastatic ovarian epithelial cancers (n = 8). Ovarian tissue was collected from surgical samples. Estrogen receptor cu and ER beta mRNA expression was compared by coamplification of the mRNA of the ERs. Expression was confirmed at the protein level by Western blot analysis using antibodies specific for each receptor. Results: Among eight primary ovarian cancer samples, three had only ER alpha, two had only ER beta, and three had both. All eight metastatic ovarian cancer tissues expressed only ER alpha mRNA and protein. Biopsies from normal ovaries had ER alpha and ER beta mRNA and protein. Two of the ovarian epithelial cancer samples were paired and showed the same results. Conclusion: We found varying amounts of ER alpha and ER beta in normal ovaries, lower levels of ER beta expression in ovarian epithelial cancer primary tumors, and only ER alpha in metastatic tumors. Our findings indicate that a fundamental difference might exist between primary and metastatic cells, which could be caused by intrinsic or extrinsic factors that regulate ER gene expression. (Obstet Gynecol 2000;96:417-21. (C) 2000 by The American College of Obstetricians and Gynecologists.).