Expression of estrogen receptor β in human colorectal cancer

摘要

AIM: To determine the expression of estrogen receptor (ER)β in Chinese colorectal carcinoma (CRC) patients. METHODS: ERβ expression in CRC was investigated by immunohistochemical staining of formalin-fixed, paraffin-embedded tissue sections from 40 CRCs, 10 colonic adenomas, and 10 normal colon mucosa biopsies. The percentage of positive cells was recorded, mRNA expression of ERα and ERβ in 12 CRC tissues and paired normal colon tissues were detected by RT-PCR. RESULTS: Positive ER immunoreactivity was present in part of normal epithelium of biopsy (2/10), adenomas (3/10), and the sections of CRC tissue, most of them were nuclear positive. In CRCs, nuclear ERβ immunoreactivity was detected in over 10% of the cancer cells in 57.5% of the cases and was always associated with cytoplasmic immunoreactivity. There was no statistical significance between ERβ positive and negative groups in regard to depth of invasion and nodal metastases. Of the 12 CRC tissues and paired normal colon tissues, the expression rate of ERα mRNA in CRC tissue and corresponding normal colon tissue was 25% and 16.6%, respectively. ERβ mRNA was expressed in 83.3% CRC tissue and 91.7% paired normal colon tissue, respectively. There was no significant difference in ERβ mRNA level between CRC tissues and paired normal colon tissues. CONCLUSION: A large number of CRCs are positive for ERβ, which can also be detected in normal colonic epithelia. There is a different localization of ERβ immunoreactivity among normal colon mucosae, adenomas and CRCs. ERα and ERβ mRNA can be detected both in CRC tissue and in corresponding normal colon tissue. A post-transcriptional mechanism may account for the decrease of ERβ protein expression in CRC tissues.