Reduction in tumor necrosis factor receptor affinity and cytotoxicity by glucocorticoids.
Micromolar concentrations of glucocorticoids rendered L-M cells (a murine tumorigenic fibroblast line) less sensitive to the cytotoxic activity of murine TNF. The potency of different steroids paralleled their known anti-inflammatory potency, and pretreatment was more effective than post treatment. Sex steroids and mineralocorticoids were ineffective. Dexamethasone also decreased the sensitivity of MCF-7 (a human mammary carcinoma line) to the cytotoxic activity of human recombinant TNF. Pretreatment of both cell lines reduced the affinity of specific cell surface receptors for the binding of their species 125I-TNF about 3-fold while retaining the same number of binding sites. The decrease in sensitivity was not due solely to the inhibition of early TNF-induced events (such as binding, internalization or signal transduction). Dexamethasone modestly enhanced inhibition beyond that of neutralizing antiserum alone when both were added midway in the L-M killing reaction (after receptor down regulation but before the onset of complete cell death).
Kull
F C
FC
Burroughs Wellcome Co., Research Triangle Park, North Carolina 27709.
D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor; D013997:Time Factors
D005938:Glucocorticoids; D011956:Receptors, Cell Surface; D018124:Receptors, Tumor Necrosis Factor; D003907:Dexamethasone