Preconditioning of 3T3 cells by fresh medium together with genistein enhances prostaglandin E(2) release

Bradykinin induced prostaglandin E(2) release from the Swiss 3T3 fibroblasts, preconditioned with fresh culture medium. Although treatment with genistein for the entire period of preconditioning and incubation with bradykinin attenuated prostaglandin E(2) release, treatment with fresh culture medium and genistein for only the preconditioning period further augmented the prostaglandin E(2) release. In the cells preconditioned with fresh culture medium and genistein, bradykinin caused the phosphorylation of protein tyrosine and mitogen-activated protein kinase/extracellular-regulated kinase (MAPK/ERK), followed by arachidonic acid release. Interestingly, preconditioning with genistein alone also caused phosphorylation and arachidonic acid release, probably reflecting rebound activation after the washout of genistein. However, preconditioning with genistein alone induced neither the augmentation of prostaglandin E(2) release nor the expression of cyclooxygenase-2. The further potentiation of bradykinin-induced prostaglandin E(2) release by combined preconditioning with fresh culture medium and genistein may be due to the activation of the MAPK/ERK-c phospholipase A(2) pathway by preconditioning with genistein.