Stromal estrogen receptors mediate mitogenic effects of estradiol on uterine epithelium

AUTOR(ES)

Cooke, P. S.

FONTE

The National Academy of Sciences of the USA

RESUMO

Estradiol-17β (E2) acts through the estrogen receptor (ER) to regulate uterine growth and functional differentiation. To determine whether E2 elicits epithelial mitogenesis through epithelial ER versus indirectly via ER-positive stromal cells, uteri from adult ER-deficient ER knockout (ko) mice and neonatal ER-positive wild-type (wt) BALB/c mice were used to produce the following tissue recombinants containing ER in epithelium (E) and/or stroma (S), or lacking ER altogether: wt-S + wt-E, wt-S + ko-E, ko-S + ko-E, and ko-S + wt-E. Tissue recombinants were grown for 4 weeks as subrenal capsule grafts in intact female nude mice, then the hosts were treated with either E2 or oil a week after ovariectomy. Epithelial labeling index and ER expression were determined by [3H]thymidine autoradiography and immunohistochemistry, respectively. In tissue recombinants containing wt-S (wt-S + wt-E, wt-S + ko-E), E2 induced a similar large increase in epithelial labeling index compared with oil-treated controls in both types of tissue recombinants despite the absence of epithelial ER in wt-S + ko-E tissue recombinants. This proliferative effect was blocked by an ER antagonist, indicating it was mediated through ER. In contrast, in tissue recombinants prepared with ko-S (ko-S + ko-E and ko-S + wt-E), epithelial labeling index was low and not stimulated by E2 despite epithelial ER expression in ko-S + wt-E grafts. In conclusion, these data demonstrate that epithelial ER is neither necessary nor sufficient for E2-induced uterine epithelial proliferation. Instead, E2 induction of epithelial proliferation appears to be a paracrine event mediated by ER-positive stroma. These data in the uterus and similar studies in the prostate suggest that epithelial mitogenesis in both estrogen and androgen target organs are stromally mediated events.

Documentos Relacionados

• Stromal Progesterone Receptors Mediate Induction of Indian Hedgehog (IHH) in Uterine Epithelium and Its Downstream Targets in Uterine Stroma
• Specificity of oligodeoxynucleotide binding of mouse uterine cytosol estradiol receptors.
• Estradiol and Tamoxifen Mediate Rescue of the Dominant-Negative Effects of Estrogen Response Element-Binding Protein in Vivo and in Vitro
• Opposing effects of estradiol and progesterone on oxytocin receptors in rabbit uterus
• Estrogenic activity of the insecticide chlordecone (Kepone) and interaction with uterine estrogen receptors.