Relationships, among the steroids, of anti-inflammatory properties and inhibition of prostaglandin production and arachidonic acid release by transformed mouse fibroblasts.

Anti-inflammatory steroids inhibit the serum-stimulated prostaglandin synthesis and release of [3H]arachidonic acid by methylcholanthrene-transformed mouse fibroblast, MC5-5. The half-maximal concentration for inhibition of both effects parallels the relative anti-inflammatory potencies of these steroids. The fatty acid cyclooxygenase activities of microsomal fractions isolated from cells that had been pretreated with dexamethasone were similar to the activities of microsomal fractions isolated from untreated cells. Intracellular as well as extracellular levels of prostaglandins in dexamethasone inhibited cells were decreased. The anti-inflammatory steroids seem to be blocking deacylation of the phospholipids or transport of the arachidonic acid, after deacylation to the cyclooxygenase.