Effects of 17 beta-estradiol and growth factors on cell proliferation and c-fos gene expression, in vitro, in endometrial cells in normal growth

Glandular epithelial cells (GEC) and stromal cells (SC) were isolated from guinea-pig endometrium and cultured separately. After the cells were made quiescent by serum depletion, cell proliferation and c-fos gene expression were investigated. Estradiol-17 beta (E2) alone had no effect on cell proliferation or c-fos gene expression. Cell proliferation was observed in SC and GEC after stimulation with insulin plus EGF and a supplementary effect was obtained when E2 was associated with these factors only in GEC. In GEC, insulin plus EGF had no effect on c-fos expression but an effect was observed when E2 was associated with these factors or with a protein synthesis inhibitor, cycloheximide (Chx) or puromycine. An E2 effect in the presence of Chx was also observed in SC. These data suggest the presence of a labile protein preventing the in vitro estrogenic action in endometrial cells.