title: Methotrexate enhances prostaglandin D2-stimulated heat shock protein 27 induction in osteoblasts.
abstract: As for the pathogenesis of rheumatoid arthritis (RA), prostaglandins (PGs) act as important mediators of inflammation and joint destruction. Among them, PGD2 is well recognized as a potent regulator of osteoblastic functions. We previously showed that PGD2 stimulates the induction of heat shock protein 27 (HSP27) via protein kinase C (PKC)-dependent p38 mitogen-activated protein (MAP) kinase and p44/p42 MAP kinase in osteoblast-like MC3T3-E1 cells. Therefore, it is a current topic to clarify how HSP27 plays a role for regulating osteoblastic functions in the lesion of RA. On the other hand, methotrexate (MTX) is one of the most effective medicines for the treatment of RA. Here, we examined the effect of MTX on PGD2-stimulated HSP27 induction in MC3T3-E1 cells. The cells were pretreated with various doses of MTX including therapeutic dosage for RA, and then stimulated by PGD2. MTX significantly enhanced the PGD2- increased levels of HSP27 in a dose-dependent manner, although MTX alone had no effect on the levels of HSP27. In addition, MTX amplified the PGD2-increased levels of HSP27 mRNA. On the contrary, MTX had little effect on PGD2-induced formation of inositol phosphates, PKC activation and phosphorylations of MAP kinases. Our results strongly suggest that MTX enhances PGD2-stimulated HSP27 induction at a point downstream from MAP kinases in osteoblasts.
authors.affiliation: Department of Pharmacology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Yoshida
authors.forename: Masayuki
authors.initials: M
authors.lastname: Niwa
authors.forename: Akira
authors.initials: A
authors.lastname: Ishisaki
authors.forename: Kouseki
authors.initials: K
authors.lastname: Hirade
authors.forename: Hidenori
authors.initials: H
authors.lastname: Ito
authors.forename: Katsuji
authors.initials: K
authors.lastname: Shimizu
authors.forename: Kanefusa
authors.initials: K
authors.lastname: Kato
authors.forename: Osamu
authors.initials: O
authors.lastname: Kozawa
mesh_terms: D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D015152:Blotting, Northern; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D004789:Enzyme Activation; D055551:HSP27 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D007295:Inositol Phosphates / Q000378:metabolism; D008727:Methotrexate / Q000494:pharmacology*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D015230:Prostaglandin D2 / Q000378:metabolism*; D011485:Protein Binding; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D000873:Anthracenes; D004268:DNA-Binding Proteins; D055551:HSP27 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; C490017:Hsf1 protein, mouse; C486699:Hspb2 protein, mouse; D007295:Inositol Phosphates; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D014157:Transcription Factors; D003609:Dactinomycin; C432165:pyrazolanthrone; D004247:DNA; D003513:Cycloheximide; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D015230:Prostaglandin D2; D008727:Methotrexate