Distinct expression patterns of ER alpha and ER beta in normal human mammary gland.
OBJECTIVE
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.
Speirs
V
V
Molecular Medicine Unit, University of Leeds, St James's University Hospital, Leeds LS9 7TF, UK. v.speirs@leeda.ac.uk
Skliris
G P
GP
Burdall
S E
SE
Carder
P J
PJ
D001940:Breast / Q000378:metabolism*; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D011960:Receptors, Estrogen / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D011960:Receptors, Estrogen