Distinct expression patterns of ER alpha and ER beta in normal human mammary gland.

AIM: Two oestrogen receptors (ERs) have been identified to date-the "classic" ER alpha and the more recently described ER beta. Although much is known about ER alpha at the mRNA and protein levels, our knowledge of the expression and distribution of ER beta protein is much more limited. The aim of this study was to compare the cellular distribution of ER alpha and ER beta in normal human mammary gland. METHODS: Formalin fixed, paraffin wax embedded material was obtained from reduction mammoplasty specimens, normal tissue adjacent to breast tumour, or fibroadenoma. Sections were immunohistochemically stained for ER alpha, ER beta, and the progesterone receptor. The staining pattern for each antibody was evaluated and compared. RESULTS: ER alpha was restricted to the cell nuclei of epithelial cells lining ducts and lobules. Although ER beta was also seen in these cells, additional strong staining was detected specifically in the cell nuclei of myoepithelial cells. Occasional staining was seen in surrounding stromal and endothelial cell nuclei and in lymphocytes. CONCLUSIONS: ER subtypes have distinct distribution patterns in the normal mammary gland. The widespread distribution of ER beta suggests that it may be the dominant ER in the mammary gland where it may be acting as a natural suppressor.

Exploring the potential chemopreventative effect of aspirin and rofecoxib on hereditary nonpolyposis colorectal cancer-like endometrial cancer cells in vitro through mechanisms involving apoptosis, the cell cycle, and mismatch repair gene expression.

Women in hereditary nonpolyposis colorectal cancer (HNPCC) families have up to a 71% lifetime risk for developing endometrial cancer (EC). This compares to the female lifetime risk for colorectal cancer (CRC) in HNPCC of 60%. The basis of HNPCC is an inherited mutation in a mismatch repair gene (MMR). Aspirin and COX2 inhibitors seem to have a chemoprotective effect on CRC in the general population and are the subject of prospective clinical studies in patients at high risk for CRC including HNPCC. There is no evidence that these agents have any protective effect against EC in the general population. This study investigated the effect of aspirin and a COX2 inhibitor (rofecoxib) on an HNPCC EC cell line model (Ishikawa) by assessing the effect on proliferation, apoptosis, the cell cycle, and MMR gene expression. Aspirin inhibits EC cell proliferation by inducing apoptosis and changes in the cell cycle. This effect is not mediated by changes in MMR gene (hMSH2) expression as assessed by quantitative reverse transcription-polymerase chain reaction. Rofecoxib inhibits EC cell proliferation; this did not appear to be mediated by induction of apoptosis, by alterations of the cell cycle, or by changes in MMR gene expression.

Evaluation of seven oestrogen receptor beta antibodies for immunohistochemistry, western blotting, and flow cytometry in human breast tissue.

Two oestrogen receptors, ER alpha and ER beta, exist. While much is known about ER alpha, the role of ER beta is still undefined, especially at the protein level. The aim of this study was to determine the utility of seven ER beta antibodies (14C8, 8D5, PAI313, PPG5/10, N19, 9.88, and D7N) raised against different domains of ER beta in three commonly used laboratory applications, namely immunohistochemistry, western blot, and flow cytometry, using human breast material. For immunohistochemical analysis of frozen material, PAI313 and D7N gave stronger and more specific signals than 14C8, 8D5, and PPG5/10. In paraffin sections, 14C8, closely followed by PPG5/10, gave by far the most superior nuclear immunoreactivity, compared with the other antibodies tested. In general, flow cytometry results mirrored the immunohistochemistry data for paraffin sections, with antibodies ranked 14C8 > 8D5> or = PAI-313 > PPG5/10 >D7N. For western blotting, 8D5 and D7N yielded the strongest and most consistent bands, with weaker bands seen with the others. It is concluded that ER beta protein can be detected using specific antibodies. However, there is considerable variation between the specificity and application of these antibodies, highlighting the fact that careful optimization is required when selecting an antibody for use in a particular laboratory technique.