Expression of estrogen receptor beta 1, beta 2, and beta 5 messenger RNAs in human breast tissue

A triple-primer PCR assay was developed, based on the coamplification of es trogen receptor (ER)-beta 1, -beta 2, and -beta 5 cDNAs, to investigate the relative expressions of the corresponding mRNAs in breast cancer lines and in 53 independent breast tumors. The expression of ER-beta 2 and ER-beta 5 mRNAs was higher than that of ER-beta 1 mRNA in both cancer cell lines and breast tumors. In breast tumors, increases in the ER-beta 2:ER-beta 1 and ER-beta 5:ER-beta 1 mRNA expression ratios were observed, which positively correlated with the level of tumor inflammation and tumor grade, respective ly. A trend toward an increase of these ratios was also found in tumors, as compared to the normal adjacent breast tissue available fur 13 cases. Our data suggest that changes in the relative expression of ER-beta 1, -beta 2, and -beta 5 mRNAs occur during breast tumorigenesis and tumor progression.