Stromal-Epithelial Interactions Modulate Estrogen Responsiveness in Normal Human Endometrium1

Abstract

The coculture of endometrial epithelial cells (EEC) with stromal cells (ESC) allows achievement of an improved in vitro system for studying interactions between cells via soluble signals. The purpose of this study was to investigate whether 17beta-estradiol and insulin can induce proliferation of EEC through ESC-secreted factors. No evidence of estrogen-induced EEC proliferation has been reported so far in the conventional culture methods. To this end, we used an in vitro bicameral coculture model where human EEC were grown on extracellular matrix-coated inserts applied in dishes containing ESC. Proliferation was assessed by tritiated thymidine incorporation. Homogeneity of endometrial cell populations was ascertained immunocytochemically. 17beta-estradiol did not induce any proliferative effect on EEC cultured alone. Endometrial epithelial cell proliferation was significantly enhanced in EEC/ESC cocultures; moreover, it was further increased by 17beta-estradiol addition. Insulin increased proliferation in EEC cultured alone, but again the effect was more pronounced in EEC/ESC cocultures. Coincubation of 17beta-estradiol and an antibody against insulin-like growth factor I (IGF I) led to neutralization of ESC-mediated EEC proliferation. This work provides evidence that the effect of 17beta-estradiol on human EEC proliferation may be mediated at least in part through ESC-secreted IGF I. We also showed that insulin effect is also partially due to ESC activation.

Estradiol, Progesterone, and Transforming Growth Factor α Regulate Insulin-Like Growth Factor Binding Protein-3 (IGFBP3) Expression in Mouse Endometrial Cells

“…The proliferation of endometrial cells is regulated by growth factors, including IGF1 produced in endometrial stromal cells (Bigsby and Cunha, 1986;Astrahantseff and Morris, 1994;Cooke et al, 1997;Pierro et al, 2001). IGF1 expression and IGFBP3 expression were conversely regulated by estrogen in endometrial stromal cells.…”

WITHDRAWN: Endometrial epithelial cell apoptosis is inhibited via a ciR8073-miR181a-neurotensis pathway during embryo implantation

“…Primary EECs were isolated and purified by digestion of trypsin, centrifugation and difference tempo adherence, and observed by light microscope, and cell purity and identification was evaluated immunocytochemically as previously described [64]. The cells were cultured to the third generation with the same cell culture system to further purify the cells.…”

Autocrine stimulation of IGF1 in estrogen-induced growth of endometrial carcinoma cells: involvement of the mitogen-activated protein kinase pathway followed by up-regulation of cyclin D1 and cyclin E

“…Such a discrepancy may be due to the absence of endometrial stroma in the in vitro experiment culturing purified glandular cells (Shiozawa et al 2001). Pierro et al (2001) reported that normal endometrial stromal cells secrete IGF1 as a paracrine factor that stimulates the proliferation of neighboring glandular cells, indicating the presence of epithelial-stromal interactions via IGF1 in normal endometrium. This is consistent with the observation that the activity of cell proliferation of normal glandular cells in vitro is very low when cultured in the absence of stromal cells.…”