Flow cytometric detection and binding studies of human endometrial stromal cell epidermal growth factor receptor in monolayer culture: influence of progesterone

Abstract

Epidermal growth factor (EGF) has been shown to modulate endometrial differentiation in vivo and in vitro. Therefore, endometrial stromal cell EGF receptors were characterized in intact endometrial stromal cells, cultured in vitro. The methods used for characterization were flow cytometry, binding and displacement studies, and gel electrophoresis followed by autoradiography. In flow cytometry the histogram of labelled stromal cells was identical to Caski cells, which served as a positive control. EGF binding revealed the typical binding hierarchy for EGF receptors. The Scatchard analysis showed a curvilinear plot with a calculated dissociation constant of 0.36 nM for high affinity binding sites. In autoradiography a band of approximately 170 kDa was visualized corresponding to the known size of the EGF receptor. The intensity of this band was increased by pretreatment of stromal cells with 10 nM progesterone for 4 days. Furthermore, stimulation with progesterone led to an increase in specific EGF binding activity of stromal cells by 21% compared to control. These data indicate that intact stromal cells in monolayer culture maintain specific EGF receptors, which are up-regulated by progesterone.

In Vivo Assessment of the Regulation of Transforming Growth Factor Alpha, Epidermal Growth Factor (EGF), and EGF Receptor in the Human Endometrium by Medroxyprogesterone Acetate

“…While EGF-R affinity appears to be higher during the late proliferative and late secretory phases of menstrual cycle (8,18), cultured endometrial cells stimulated with estrogen or progesterone increase their EGF-R content (8,19) and binding activity (8,20). In the present study, EGF-R immunostaining was stronger in the glandular epithelium of secretory endometrium, especially in the group treated with MPA, suggesting that stimulation of progesterone receptor may indeed play a role in the control of endometrial EGF-R expression.…”

“…The regulation of EGF-R and its ligands by ovarian steroid hormones in the human endometrium remains open to debate since observational (8,9) and in vitro (14,18,20) studies have produced conflicting results regarding the effects of estradiol and progesterone on EGF-R level. Here we show that administration of MPA increased EGF-R immunoreactivity in the endometrium, whereas TGFα and EGF did not change from proliferative to secretory phases of menstrual cycle and were not modified by treatment with MPA.…”