EXPRESSION OF ESTROGEN RECEPTOR-BETA IN HUMAN BREAST-TUMORS

The expression of a recently described novel estrogen receptor, ER-bet a, was detected in several human breast tumor biopsy samples and sever al human breast epithelial cell lines using reverse transcription and polymerase chain reaction (RT-PCR) analysis. Cloning and sequencing of the PCR product from a breast tumor confirmed the identity of the seq uence with that of the ER-beta mRNA previously reported in human testi s. The expression of ER-beta was not correlated with that of ER-alpha, and both ER-alpha positive and ER-alpha negative cell lines expressed ER-beta mRNA. However, some breast tumors and some cell lines coexpre ss ER-beta and ER-alpha mRNA. Our data support a possible role for ER- beta in human breast cancer.