Co-expression of estrogen receptor-alpha and targets of estrogen receptor action in proliferating monkey mammary epithelial cells.
BACKGROUND
Failure to detect co-expression of estrogen receptor-alpha (ERalpha) and proliferation 'markers' such as Ki67 in human mammary epithelium led to the view that estrogen acts indirectly to stimulate mammary epithelial proliferation. The mitotic index was so low in prior studies, however, that transient co-expression of ERalpha and Ki67 during the cell cycle could have been below detection limits.


METHODS
Immunohistochemistry was used on mammary tissue sections from estrogen treated rhesus monkeys to investigate co-expression of ERalpha and the proliferation antigen Ki67. Using the same methods, we investigated the cell localization of proteins involved in estrogen-induced proliferation, including cyclin D1, stromal cell-derived factor (SDF)-1, and MYC.


RESULTS
ERalpha was co-expressed with the proliferation marker Ki67 as well as with SDF-1, MYC and cyclin D1 in mammary epithelial cells from estrogen-treated monkeys.


CONCLUSIONS
ERalpha is expressed in proliferating mammary epithelial cells together with the estrogen-induced proteins MYC, cyclin D1 and SDF-1, consistent with a direct mitogenic action by estrogen in primate mammary epithelium.
Dimitrakakis
Constantine
C
Developmental Endocrinology Branch, NICHD, NIH, Bethesda, MD 20892, USA. dimitrac@mail.nih.gov
Zhou
Jian
J
Wang
Jie
J
Matyakhina
Ludmila
L
Mezey
Eva
E
Wood
Jesse Xiyu
JX
Wang
Daniel
D
Bondy
Carolyn
C
D000818:Animals; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000096:biosynthesis; D019938:Cyclin D1 / Q000096:biosynthesis; D004847:Epithelial Cells / Q000502:physiology; D047628:Estrogen Receptor alpha / Q000032:analysis / Q000096:biosynthesis*; D004967:Estrogens / Q000502:physiology*; D005260:Female; D016259:Genes, myc; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000032:analysis / Q000096:biosynthesis*; D008253:Macaca mulatta; D008321:Mammary Glands, Animal / Q000166:cytology*
C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D047628:Estrogen Receptor alpha; D004967:Estrogens; D019394:Ki-67 Antigen; D019938:Cyclin D1