Hydrocortisone-dependent alterations of transcriptional activity in WI38 cells

Dexamethasone induced proliferation of cultured retinal pigment epithelial cells

Dexamethasone (DEX) is a glucocorticoid that is widely used after vitreoretinal surgery and may have mitogenic properties. This study was initiated to determine if human cultured retinal pigment epithelium (RPE) cells express glucocorticoid receptor and proliferate in response to DEX stimulation. Glucocorticoid receptor mRNA was detected in RPE cells by means of reverse transcriptase polymerase chain reaction. To determine the effect of DEX on RPE cell proliferation in vitro, we cultured human RPE cells with various concentrations for DEX for 5 days and determined the effects on cell number and incorporation of tritiated thymidine. DEX treatment with a DEX dose of 1 microgram/ml in the presence or absence of serum resulted in a maximal 2-3 times increase in cell number. Autoradiography after thymidine incorporation revealed a greater than 2-fold increase in incorporating cells at this same dose. These results indicate that DEX causes cultured human RPE cells to proliferate and suggest that it may have a growth factor-like action.

Effects of various steroids on in vitro lifespan and cell growth of human fetal lung fibroblasts (WI-38)

Human fetal lung fibroblasts, WI-38, were cultivated in a medium containing various steroids. A dose-response curve constructed by counting the number of cells on day 16, or at regular intervals, showed that glucocorticoids (hydrocortisone and cortisone) and mineralocorticoids (aldosterone and deoxycorticosterone) caused an increase in cell density when added at physiological concentrations or higher. On the other hand, androgens (testosterone, dihydrotestosterone, and dehydroepiandrosterone), estrogen (17 beta-estradiol), and progesterone caused a decrease in cell density at higher concentrations (5 micrograms/ml, or more) although these had no effect on cell density at concentrations lower than 0.5 micrograms/ml. With cells grown from population doubling 31 in a medium containing steroids, it was shown that hydrocortisone extended the in vitro lifespan of WI-38 cells at concentrations of both 5 micrograms/ml and 0.5 micrograms/ml, while dehydroepiandrosterone, 17 beta-estradiol, and progesterone caused a shortening in lifespan at only 5 micrograms/ml. These results suggest that there is a direct relationship between the effects of steroids on cell growth and the lifespan of human fetal lung fibroblasts.