An Anti-Inflammatory Benzamide Derivative Inhibits the Protein Kinase C (PKC)-Dependent Pathway of ERK2 Phosphorylation

We have previously described benzamide derivatives that in-hibited tumor necrosis factor (TNF) production from activated macrophages (Mf) probably by interacting with a protein ki-nase C (PKC)-dependent pathway. To investigate their mode of action further, we first tested their effect on isolated PKC in vitro, using the selective inhibitor bisindolylmaleimide (BIM) as a positive control. We found that our representative compound JM34 did not inhibit PKC activity in vitro. We then investigated pathways located downstream of PKC and focused on the Raf1/MEK1,2/Erk1,2 cascade known to be preferentially acti-vated by PKC activators such as phorbol esters. We found that JM34 dose-dependently inhibited Erk2 phosphorylation in Mf stimulated by phorbol dibutyrate and calcium ionophore (max-imal inhibition of 85 % at 300 mM). BIM at 3 mM totally abro