title: Methylsulfonylmethane Inhibits RANKL-Induced Osteoclastogenesis in BMMs by Suppressing NF-κB and STAT3 Activities.
abstract: Osteoclast differentiation is dependent on the activities of receptor activator NF-kB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). Given that RANKL plays a critical role in osteoclast formation and bone resorption, any new compounds found to alter its activity would be predicted to have therapeutic potential for disorders associated with bone loss. Methylsulfonylmethane (MSM) is a naturally occurring sulfur compound with well-documented anti-oxidant and anti-inflammatory properties; currently its effects on osteoclast differentiation are unknown. We sought to investigate whether MSM could regulate osteoclastogenesis, and if so, its mechanism of action. In this study, we investigated the effects of MSM on RANKL-induced osteoclast differentiation, together with STAT3's involvement in the expression of osteoclastic gene markers. These experiments were conducted using bone marrow derived macrophages (BMMs) and cell line material, together with analyses that interrogated both protein and mRNA levels, as well as signaling pathway activity. Although MSM was not toxic to osteoclast precursors, MSM markedly inhibited RANKL-induced TRAP activity, multinucleated osteoclast formation, and bone resorptive activity. Additionally, the expression of several osteoclastogenesis-related marker genes, including TRAF6, c-Fos, NFATc1, cathepsin K, and OSCAR were suppressed by MSM. MSM mediated suppression of RANKL-induced osteoclastogenesis involved inhibition of ITAM signaling effectors such as PLCγ and Syk, with a blockade of NF-kB rather than MAPK activity. Furthermore, MSM inhibited RANKL-induced phosphorylation of STAT3 Ser727. Knockdown of STAT3 using shRNAs resulted in reduced RANKL-mediated phosphorylation of Ser727 STAT3, and TRAF6 in cells for which depletion of STAT3 was confirmed. Additionally, the expression of RANKL-induced osteoclastogenic marker genes were significantly decreased by MSM and STAT3 knockdown. Taken together, these results indicate that STAT3 plays a pivotal role in RANKL-induced osteoclast formation, and that MSM can attenuate RANKL-induced osteoclastogenesis by blocking both NF-kB and STAT3 activity.
authors.affiliation: Department of Pathology, School of Medicine, Institute of Biomedical Science and Technology, Konkuk University, Seoul, 143-701, Republic of Korea.
authors.forename: Youn Hee
authors.initials: YH
authors.lastname: Joung
authors.affiliation: Department of Pathology, School of Medicine, Institute of Biomedical Science and Technology, Konkuk University, Seoul, 143-701, Republic of Korea.
authors.forename: Pramod
authors.initials: P
authors.lastname: Darvin
authors.affiliation: Department of Pathology, School of Medicine, Institute of Biomedical Science and Technology, Konkuk University, Seoul, 143-701, Republic of Korea.
authors.forename: Dong Young
authors.initials: DY
authors.lastname: Kang
authors.affiliation: Department of Pathology, School of Medicine, Institute of Biomedical Science and Technology, Konkuk University, Seoul, 143-701, Republic of Korea.
authors.forename: Nipin
authors.initials: N
authors.lastname: Sp
authors.affiliation: Department of Pathology, School of Medicine, Institute of Biomedical Science and Technology, Konkuk University, Seoul, 143-701, Republic of Korea.
authors.forename: Hyo Joo
authors.initials: HJ
authors.lastname: Byun
authors.affiliation: Department of Food Science and Biotechnology of Animal Resources, Konkuk University, Seoul, 143-701, Republic of Korea.
authors.forename: Chi-Ho
authors.initials: CH
authors.lastname: Lee
authors.affiliation: Department of Animal Biotechnology, Chonbuk National University, Jeonju, 561-756, Republic of Korea.
authors.forename: Hak Kyo
authors.initials: HK
authors.lastname: Lee
authors.affiliation: Department of Pathology, School of Medicine, Institute of Biomedical Science and Technology, Konkuk University, Seoul, 143-701, Republic of Korea.
authors.forename: Young Mok
authors.initials: YM
authors.lastname: Yang
mesh_terms: D000818:Animals; D015415:Biomarkers; D001862:Bone Resorption / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D015870:Gene Expression; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D010010:Osteoclasts / Q000187:drug effects / Q000378:metabolism; D053245:RANK Ligand / Q000378:metabolism* / Q000494:pharmacology; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013450:Sulfones / Q000494:pharmacology*; D000071681:Tartrate-Resistant Acid Phosphatase / Q000378:metabolism
chemical_list: D015415:Biomarkers; D016328:NF-kappa B; D053245:RANK Ligand; D050796:STAT3 Transcription Factor; D013450:Sulfones; C025910:dimethyl sulfone; D000071681:Tartrate-Resistant Acid Phosphatase; D004121:Dimethyl Sulfoxide