一般口演　骨1

[O3-E-AM1-02] Positive regulation of S-adenosylmethionine on chondrocytic differentiation via stimulation of polyamine production and gene expression of chondrogenic differentiation factors

〇Loc Dinh Hoang^1,2, Aoyama eriko¹, Satoshi Kubota³, Kuboki Takuo², Takigawa Masaharu¹ (1. Adv Res Ctr Oral Craniofacial Sci, Okayama Univ Grad Sch Med Dent Pharm Sci, 2. Dept Oral Rehabil Regen Med, Okayama Univ Grad Sch Med Dent Pharm Sci, 3. Dept Biochem Mol Dent, Okayama Univ Grad Sch Med Dent Pharm Sci)

キーワード：S-adenosylmethionine、cartilage、Polyamine

S-adenosylmethionine (SAM) is demonstrated as universal methyl donor functioning in transmethylation, transsulfuration, polyamine synthesis pathways and has been found to be a potential therapy in the management of degenerative cartilage disease but the mechanism of SAM action remains unclear. Our previous studies reported that polyamines were involved in chondrogenesis, increased GAG production – a specific marker of differentiated phenotype of chondrocyte in culture. We also reported that CCN2 (Communication Network factor 2) played an important role in proliferation and differentiation of chondrocytes. Thus, we hypothesized that polyamine production and chondrogenesis associated factors such as CCN2 could be candidates involved in SAM action on chondrocytes. In this study, we found that exogenous SAM treatment enhanced proteoglycan production but did not promote cell proliferation in rat chondrosarcoma-derived cell lines (RCS) and human chondrosarcoma-derived cell lines (HCS-2/8). Quantitative RT-PCR revealed that gene expressions of cartilage markers (aggrecan, type II collagen and SOX9: sry-box transcription factor 9) and chondroitin sulfate chains biosynthesis enzymes (chondroitin synthase, chondroitin sulfate N-acetylgalactosaminyltransferase 1) in both RCS and HCS-2/8 cells were enhanced after 3 days of SAM treatment. These results were supported by the fact that the blockade of MAT2A enzyme catalyzing for intracellular SAM biosynthesis restrained the stimulative effect of SAM on chondrocytic phenotype. Here we found that exogenous SAM increased gene expression of CCN2 in both RCS and HCS-2/8 cells, which also was inhibited by the suppression of intracellular SAM biosynthesis. On the other hand, we detected intracellular polyamine in chondrocytes labelled as TAMRA fluorescence positive cells with polyamineRED staining and high performance liquid chromatography and they all revealed higher polyamine level in SAM-treated culture than control culture. Interestingly, the stimulatory effect of SAM on chondrocyte differentiation determined by aggrecan accumulation and gene expression of Col2a1 and Acan was also observed in pre-chondrocytic cell line ATDC5. These results suggested that polyamine synthesis and stimulation of gene expression of chondrogenic differentiation factors such as CCN2, both of which might interact with each other and account for the mechanism of SAM action on chondrocytes.