Growth factor effects on endometrial epithelial cell differentiation and protein synthesis in vitro

To develop a baseline for projected studies of a rat endometriosis model.

We investigated the effects of two macrophage-related growth factors, platelet-derived growth factor (PDGF) and transforming growth factor-beta (TGF-beta), on proliferation, in vitro differentiation, and protein secretion of uterine epithelial cells from immature rats. Uterine epithelial cells grown on matrix covered filters were treated with growth factors (GFs) or estrogen and/or P. Incorporation of [35S]methionine by polarized uterine epithelial cell proteins and secretion of labeled proteins into apical and basal culture medium were examined.

Department of Cell Biology, Baylor College of Medicine, Houston, Texas.

Cell associated and secreted proteins were resolved by gel electrophoresis, fluorography, and immunoblotting. Proliferation was quantified by cell counts in parallel cultures by hemocytometer.

Estrogen and P increase protein synthesis by uterine epithelium. Transforming growth factor-beta depressed protein synthesis and secretion in uterine epithelial cells. Platelet-derived growth factor appears to have no effect on epithelial protein synthesis or secretion and does not modulate the effect of TGF-beta. Estrogen and P increase complement component 3 (C3) production by epithelial cells.

Macrophage-secreted GFs may play a role in the development and maintenance of ectopic endometrial tissue. Both TGF-beta and ovarian steroids may participate in the dynamic regulation of protein synthesis by ectopic uterine epithelium. These molecules may indirectly affect the macrophage-stromal axis through nonspecific modulation of C3 secretion. Platelet-derived growth factor appears to have no direct effect on uterine epithelial cells. The recognized effect of PDGF on ectopic endometrial tissue is most likely mediated via the stromal component.