Detection of glucocorticoid receptors on Friend erythroleukemia cells.

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Abstract
Dimethyl sulfoxide-induced differentiation of [mouse] Friend erythroleukemia cells was inhibited by steroids. These cells were examined for glucocorticoid receptor presence. Direct dexamethasone binding assessment revealed high-affinity dexamethasone receptors on untreated cells. Specific [3H]dexamethasone binding was dose dependent. At a concentration of 10-8M, almost all binding sites were occupied. The mean binding site number/cell in 2 separate experiments was 8045 and 7191, respectively, and the Kd varied between 3.38 .times. 10-9 M. Dimethyl sulfoxide treatment led to a decrease in the number of dexamethasone binding sites on the cells induced to differentiate. After 5 days of treatment, the mean number of sites per cell was reduced to 1216 and 896 in 2 experiment, with a Kd of 5 .times. 10-9 M. Dexamethasone treatment resulted in a moderate decrease in the efficiency of colony formation within 72 h after the cells were plated in methylcellulose. The mechanism of this inhibitory effect was unknown. It was also dose dependent and could be abrogated by appropriate progesterone or 11-deoxycortisone concentrations. Steroid effects on growth and differentiation of erythroleukemia cells may be mediated via glucocorticoid receptors.