Estrogen receptor β is expressed in human colorectal adenocarcinoma

Estrogen receptor β (ER-β) has recently been detected in a human colon cancer cell line. The aim of this work was to determine whether ER-β is expressed in human colorectal carcinoma (CRC) tissue and the extent of this expression. ER-β expression in CRC was-investigated by immunohistochemical staining of sections of formalin-fixed, paraffin-embedded tissue from 55 CRC. The percent of positive cells was recorded. ER-β immunoreactivity was always present in normal epithelium and adenomas in the same sections of some CRC and was always nuclear. In CRC, nuclear ER-β immunoreactivity was detected in \u3e10% of the cancer cells in 67% of the cases and was almost always associated with cytoplasmic immunoreactivity. There were no statistically significant differences between the ER-β-positive and -negative groups in regard to depth of invasion, nodal metastases, or survival, regardless of the cut-off value used. We conclude that (1) a significant number of CRCs are positive for ER-β. (2) estrogen may play an important role in the proliferation of normal colonic epithelium, and (3) there is differential localization of ER-β immunoreactivity between normal colon, adenomas, and CRCs. Whether different ER-β isoforms are differentially expressed in CRCs, and whether human CRCs respond to treatment with antiestrogens, is the subject of studies currently in progress. Copyright © 2001 by W.B. Saunders Company