cortodoxone and Leukemia

Cortexolone functions as an antiglucocorticoid in the human leukemic cell line CEM-C7, since it blocks the growth inhibition and cell lysis mediated by the potent agonist triamcinolone acetonide (TA). At high concentrations (10(-5) M) cortexolone alone is inactive. The ability of cortexolone to block the TA-mediated biological effects is reflected in its ability (1000-fold molar excess) to effectively block the binding of [3H]TA to the cytoplasmic unactivated form of the receptors eluted from DEAE-cellulose at approx. 180 mM potassium phosphate (KP). Likewise a 1000-fold molar excess of TA inhibits the specific binding of [3H]cortexolone to the unactivated receptors and to a peak which elutes at low salt concentration (35 mM KP) but does not appear to represent activated [3H]cortexolone-receptor complexes. Thermal activation/transformation (25 degrees C for 30 min +/- 10 mM ATP) of the [3H]TA-receptor complexes significantly enhances the subsequent DNA-cellulose binding capacity of these complexes and also results in their elution from DEAE-cellulose at the low salt (50 mM KP) activated position. In contrast, exposure of the cytoplasmic [3H]cortexolone-receptor complexes to identical in vitro activating (transforming) conditions fails to enhance subsequent DNA-cellulose binding capacity or to result in the appropriate shift in DEAE-cellulose elution profile. This inability of [3H]cortexolone to facilitate activation/transformation of receptors was also verified using cytosol prepared from the glucocorticoid-resistant 'activation-labile' mutant, 3R7. Taken collectively the data suggest that cortexolone, unlike an agonist such as TA, fails to promote in vitro activation/transformation, a conformational change which also occurs in vivo under physiological conditions and is a prerequisite for nuclear binding.

Topics: 17-Hydroxycorticosteroids; Cell Line; Chromatography, DEAE-Cellulose; Cortodoxone; Cytoplasm; DNA; Drug Resistance; Glucocorticoids; Humans; Leukemia; Mutation; Receptors, Glucocorticoid; Triamcinolone Acetonide

A unique human T-leukemia cell line highly sensitive to dexamethasone-induced lysis is described. The cell line designated Be13 is killed readily within 24 hr by 10(-9) M dexamethasone. No lysis is induced by nonglucocorticoid steroids. The lysis is mediated via specific cytoplasmic receptors and is efficiently blocked by the antagonist cortexolone. The inhibiting effect of actinomycin D and cycloheximide on the lytic process suggests the involvement of gene activation and destruction of the cells by an "autolytic protein." Kinetic studies imply that the lytic process is induced during a distinct phase of the cell cycle. Dexamethasone, however, does not cause an arrest in a distinct phase of the cell cycle. The Be13 cell is a unique human cell line killed directly by glucocorticoids, and it may serve as a suitable in vitro model for studying the lytic effect of glucocorticoids on the proliferating compartment of human leukemias.

Topics: Cell Line; Cell Survival; Cortodoxone; Dexamethasone; Estradiol; Humans; Hydrocortisone; Kinetics; Leukemia; Microscopy, Electron; Progesterone; T-Lymphocytes; Testosterone