Expression levels of estrogen receptor-alpha, estrogen receptor-beta, coactivators, and corepressors in breast cancer.

Abstract

Recent studies have indicated that a complex machinery of transactivation of target genes by estrogen or antiestrogen through estrogen receptor (ER) exists. However, the substantial roles of ER-beta, coactivators, and corepressors in the development and progression of breast cancer remain to be elucidated. To obtain some clue to these roles, we screened the expression levels of ER-alpha, ER-beta, coactivators (SRC-1, TIF2, AIB1, CBP, and P/CAF) and corepressors (N-CoR and SMRT) in 6 normal mammary glands, 6 intraductal carcinomas, 22 invasive ductal carcinomas, and 7 breast cancer cell lines using a multiplex reverse transcription-PCR. ER-alpha mRNA expression levels significantly correlated with ER-alpha protein levels measured by enzyme immunoassay in the breast cancer tissues and cell lines. A significant correlation of expression levels was observed between ER-alpha and TIF2, AIB1, P/CAF, and N-CoR, and between ER-beta and AIB1 and CBP in the tissue samples. A significant correlation was also observed between ER-alpha and ER-beta and between ER-beta and CBP in the cell lines. The expression levels of ER-alpha, TIF2, and CBP were significantly higher in the intraductal carcinomas than those in the normal mammary glands. In addition, the expression levels of ER-alpha and N-CoR were significantly higher in the intraductal carcinomas than those in the invasive ductal carcinomas. These findings suggest a positive correlation of expression levels among ER-alpha and cofactors and among ER-beta and cofactors, an up-regulation of expression levels of ER-alpha and cofactors during the development of intraductal carcinomas from normal mammary glands, and a decrease in their expression levels during the progression of breast cancer.

• Authors: J Kurebayashi, T Otsuki, H Kunisue, K Tanaka, S Yamamoto, H Sonoo
• Journal: Clinical cancer research : an official journal of the American Association for Cancer Research (Clin Cancer Res) Vol. 6 Issue 2 Pg. 512-8 (Feb 2000) ISSN: 1078-0432 [Print] United States
• PMID: 10690532 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• DNA Primers
• Estrogen Receptor alpha
• Estrogen Receptor beta
• RNA, Messenger
• Receptors, Estrogen
• Repressor Proteins
• Trans-Activators
• Transcription Factors

Topics

• Breast (metabolism)
• Breast Neoplasms (genetics, pathology, surgery)
• DNA Primers
• Estrogen Receptor alpha
• Estrogen Receptor beta
• Female
• Gene Expression Regulation, Neoplastic
• Humans
• RNA, Messenger (genetics)
• Receptors, Estrogen (genetics)
• Repressor Proteins (genetics)
• Reverse Transcriptase Polymerase Chain Reaction (methods)
• Trans-Activators (genetics)
• Transcription Factors (genetics)
• Transcription, Genetic
• Tumor Cells, Cultured