REGULATION OF PARATHYROID HORMONE-RELATED PROTEIN GENE-EXPRESSION IN HUMAN ENDOMETRIAL STROMAL CELLS IN CULTURE

The regulation of PTH-related protein (PTH-rP) gene expression by human endometrial stromal cells in monolayer culture was evaluated. 17Beta-estradiol (E2), interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNFalpha), endothelin-1 (ET-1), transforming growth factor-beta1 (TGFbeta1), and serum stimulated PTH-rP production (evaluated by immunoassay of PTH-rP in the culture medium) by these cells. Treatment of endometrial stromal cells with E2 plus a Progestin, medroxy-progesterone acetate (MPA), caused a decrease in PTH-rP production. PRL, epidermal growth factor, and dexamethasone, which are known to affect PTH-rP production (increase or decrease) in other cells, were ineffective in altering PTH-rP production in endometrial stromal cells, as were a number of other growth factors, viz. TGFalpha, platelet-derived growth factor, and basic fibroblast growth factor, and metabolites of progesterone. The effects of E2 and MPA on PTH-rP gene expression in these cells were investigated in detail. E2 (50 nM) increased PTH-rP mRNA levels (at 2, 4, 8, 12, and 24 h). When serum (10%) was present in the medium, E2 (50 nM) did not increase PTH-rP production or PTH-rP mRNA levels, and in the presence of serum, E2 plus MPA did not decrease PTH-rP production. In cells that were pretreated with E2 (50 nM) for 48 h before treatment (18 h) with ET-1, TNFalpha, tetradecanoylphorbol acetate, and TGFbeta1, the production of PTH-rP was greater than that in cells not pretreated with estrogen. The effect of treatment of endometrial stromal cells with MPA on PTH-rP mRNA levels (at 2, 4, 8, and 12 h) was variable, but in all studies conducted, PTH-rP production after 18 or 24 h of progestin treatment was not increased compared with that in nontreated cells. We conclude that estrogen acts directly in endometrial stromal cells to increase PTH-rP mRNA levels and PTH-rP protein production. In addition IL-1beta. TNFalpha, ET-1, TGFbeta1, and serum stimulate PTH-rP production by these cells. With the exception of serum, the effects of most of the other agents identified in this study to stimulate PTH-rP production were at least additive with that of E2.