Glucocorticoid-resistant Human Acute Lymphoblastic Leukemic Cell Line with Functional Receptor1

A receptor-containing, steroid-resistant clone of CEM cells, CEM-C1, was isolated without selective pressure from the wildtype population. The biological and physicochemical properties of glucocorticoid receptors in CEM-C1 cells were compared to those from a clone (CEM-C7) sensitive to glucocorticoid-mediated lysis. In a whole-cell binding assay, CEM-C1 cells exhibited high affinity for [3H]dexamethasone (K,, 22 nw), nuclear translocation of steroid:receptor complex (nt, 43%) and were found to contain, on the average, 12,000 receptor sites/cell (R0).These steroid-binding parameters were similar to those displayed by wild-type CEM-C7 cells: «<,, 19 nw; nt, 47%; and R0, -14,000 sites/cell. The ion-exchange and gel permeation profiles were indistinguishable from those of identically treated CEM-C7 cytosols. Thus, diethylaminoethyl cellulose chromatography of CEMC1 cytosol showed that [3H]triamcinolone acetonide:receptor complex was eluted at 50 mw phosphate and 220 rriM phosphate under "activating" and "nonactivating" conditions, respectively. Receptor complex of activated CEM-C1 cytosol bound to DNAcellulose and was eluted at 100 mw salt. Filtration of unactivated CEM-C1 cytosol over Sephacryl S-300 generated a single peak of radioactivity for receptor complex with a calculated Stokes' radius of 55 to 59 A. Dexamethasone induced glutamine synthetase in CEM-C1. The dose dependence (50% effective dose, ~20 nw) and maximal fold increase (1.9,1 ¿¿M dexamethasone) were comparable to those observed in CEM-C7. Since CEM-C1 cells contain apparently normal, functional cytosolic receptor, the results suggest that resistance to glucocorticoid in these cells involves a defect(s) at another locus.