Glucocorticoid receptors in WI-38 fibroblasts: characterization and changes with population doubling in culture

A high-affinity dexamethasone binding macromolecule was identified in WI-38 human fetal lung fibroblasts. High specificity of binding for glucocorticoids was shown by competition studies in which binding of dexamethasone was inhibited by cortisol and corticosterone but not by testosterone or 17 beta-estradiol. WI-38 cells exposed to [3H]dexamethasone at 30 degrees C were able to transfer the 3H-labeled steroid-receptor complex to the nuclear materal. A reduction of 30--50% was observed in the number of [3H]dexamethasone-receptor binding sites per cell as well as in the nuclear fraction of the cells as a function of age (passage levels 27 and 54). However, in the same cells no significant changes in affinity of receptor for [3H]dexamethasone as a function of the two passage levels were detected.