Phenethyl isothiocyanate suppresses receptor activator of NF-kappaB ligand (RANKL)-induced osteoclastogenesis by blocking activation of ERK1/2 and p38 MAPK in RAW264.7 macrophages.
Osteoclastogenesis is induced by differentiation of hemopoietic cells of monocyte-macrophage lineage into bone-resorbing osteoclasts. The process is initiated by receptor activator of NF-kappaB ligand (RANKL) and resultant activation of mitogen-activated protein kinases (MAPK), including extracellular signal-regulated kinase (ERK)1/2, as well as the NFkappaB pathway. Phenethyl isothiocyanate (PEITC), a phytochemical present in various cruciferous plants, has been shown to disrupt those signaling pathways in several cell types. In this study, we examined the efficacy of PEITC for suppressing RANKL-induced osteoclastogenesis in RAW264.7 murine macrophages and addressed the underlying molecular mechanisms. PEITC (2-10 microM) suppressed osteoclastogenesis in a concentration dependent manner, as detected by tartarate-resistant acid phosphatase (TRAP) activity and microscopic observations. RANKL-up-regulated extracellular signal-regulated kinase (ERK)1/2 and p38 mitogen-activated protein kinase (MAPK) activities were attenuated by PEITC, whereas c-Jun N-terminal kinase (JNK1/2) activation was increased. PEITC also abrogated the RANKL-induced degradation of IkappaB-alpha, a suppressive partner of nuclear factor kappaB (NFkappaB), thereby inhibiting transcription activity, as detected by a reporter assay. In addition, PEITC reduced the level of NFkappaB-dependent mRNA expression of nuclear factor of activated T cell (NFAT)c1, a master regulator of osteoclastogenesis. Our results indicate that PEITC is a promising agent for treatment of osteoclastogenesis with a reasonable action mechanism.
Murakami
Akira
A
Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan. cancer@kais.kyoto-u.ac.jp
Song
Meiyu
M
Ohigashi
Hajime
H
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D017879:Isothiocyanates / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology*; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors*; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D050778:NFATC Transcription Factors / Q000037:antagonists & inhibitors; D010010:Osteoclasts / Q000187:drug effects / Q000502:physiology*; D053245:RANK Ligand / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors*
D017879:Isothiocyanates; D016328:NF-kappa B; D050778:NFATC Transcription Factors; C494005:Nfatc1 protein, mouse; D053245:RANK Ligand; C505689:Tnfsf11 protein, mouse; C005441:phenylisothiocyanate; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases