CKD712, (S)-1-(α-naphthylmethyl)-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, inhibits the lipopolysaccharide-stimulated secretion of HMGB1 by inhibiting PI3K and classical protein kinase C

CKD712, (S)-1-(α-naphthylmethyl)-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, was considered as a new effective drug candidate to sepsis, based on its anti-inflammatory activity. It was reported that CKD712 inhibited various signal pathways which play a key role in production of proinflammatory cytokines. Here, we examined the effect of CKD712 on the secretion of high mobility group box 1 (HMGB1), which is one of the proinflammatory cytokines. CKD712 can reduce Gram-negative lipopolysaccharide (LPS)- and Gram-positive lipoteichoic acid (LTA)-stimulated HMGB1 secretion in RAW264.7 and human peripheral blood monocytes (PBMo), and also reduce LPS-induced nucleocytoplasmic translocation of HMGB1 1 h before or after LPS treatment. CKD712 could dose-dependently inhibit the activation of PI3K and PI3K-dependent kinase 1 (PDK1), which are involved in HMGB1 secretion signaling pathway. In addition, CKD712 inhibited classical protein kinase C (cPKC), the effective kinase for phosphorylation of HMGB1 for secretion, however, had no effect on histone acetyl-transferase activity, which is another mechanism known for HMGB1 secretion. Thus, we suggest that CKD712 could inhibit LPS- and LTA-stimulated HMGB1 secretion through the inhibition of HMGB1 phosphorylation by inhibiting PI3K-PKC signaling pathway.