Expression of estrogen receptors alpha and beta in soft tissue sarcomas: Immunohistochemical and molecular analysis

Sex hormones can regulate differentiation and growth of mesenchymal cells and their neoplastic counterparts. This study aims to investigate the expression status of estrogen receptors (ER), ER alpha and ER beta, in a variety of soft tissue sarcomas. One hundred and twenty soft tissue sarcomas were immunohistochemically examined for the expression of ER alpha and ER beta proteins. Fifty-six tumors were further analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and 30 tumors were further analyzed by in situ hybridization (ISH) assay for their gene expression. The expression level of ER proteins was assessed in correlation with clinicopathological parameters such as patients' age, gender, and tumor Ki-67 labeling index. Forty-five (37.5%) tumors expressed ER alpha protein and 52 (43.3%) tumors expressed ER beta protein at variable levels. Both receptors were expressed with relatively high frequencies in several types of tumors (e.g. dermatofibrosarcoma protuberance, well-differentiated liposarcoma, myxoid liposarcoma, and myxoid malignant fibrous histiocytoma). A positive correlation was seen between the expression levels of ER alpha and ER beta in the current series. Thirty-one of the 42 informative cases examined by RT-PCR and 15 of the 16 informative tumors examined by ISH showed compatible results with those by immunohistochemistry. Neither gender nor age had a significant influence on the ER expression status. No significant correlation between the expression level of either type of ER and the tumor proliferation activity was identified. The results indicate that both ER isoforms are frequently expressed in certain subsets of soft tissue sarcomas, but their expression levels seem unrelated to the tumor proliferation activity.