Effect of the glucocorticoid receptor antagonist RU486 on GRE promoter activity after AdGRE.CAT infection of HeLa cells in vitro. The cells were incubated with the AdGRE.CAT vector (25 moi) for 24 hours to transfer the GRE.CAT expression cassette, followed by the addition of dexamethasone (Dex) and RU486 as indicated. (A) Effect of dexamethasone and RU486 added together. Twenty-four hours after infection with AdGRE.CAT, dexamethasone (25 nmol/L) and various concentrations of RU486 (10−7 to 10−5mol/L) were added together, and the incubation continued for 24 hours. Shown are data for CAT activity with dexamethasone (•) or without dexamethasone (○). (B) Effect of dexamethasone or RU486 added in series. Twenty-four hours after vector administration, the cells were pre-incubated for 6 hours with dexamethasone, then with RU486 for an additional 18 hours. Parallel cultures were evaluated in reverse order (RU486 for 6 hours and then dexamethasone for an additional 18 hours). Shown is CAT activity at the end of the incubation. The results are expressed as the mean ± SEM of three experiments.
