title: Expression of MMP-13 in osteoblast cells and rat tibia after exposure to gamma rays or accelerated carbon ions.
abstract: In past research, we found that carbon ion irradiation increased bone volume in rats, and a significant amount of cartilage remained inside the carbon ion-irradiated trabeculae. The amounts of matrix metalloproteinase 13 (MMP-13) mRNA in osteoblast-like MC3T3-E1 cells tended to decrease after carbon ion irradiation. The level of MMP-13 mRNA in non-irradiated cells was stable during the experimental period, but in gamma ray-irradiated cells it tended to increase. When localization of MMP-13 in locally irradiated experimental rats was investigated, it was found in the marginal trabeculae in both non-irradiated and gamma ray-irradiated animals. MMP-13 was detected in osteoid and neogenetic bone in the trabeculae surface. The trabeculae in carbon ion-irradiated bone remained cartilaginous. Carbon ion-irradiated rats exhibited weak expression of MMP-13 around the cartilage inside the trabeculae. We conclude that carbon ion irradiation reduced expression of MMP-13, thus suppressing both chondrocyte maturation and cartilage resorption. Increases in hyperplasia of the bone trabeculae and of bone volume were caused by ongoing bone addition and calcification in the absence of sufficient cartilage resorption.
authors.affiliation: Department of Oral and Maxillofacial Radiology, Hiroshima University Hospital, 2-3 Kasumi-1, 734-8553 Hiroshima, Japan. jiri@hiroshima-u.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Sawajiri
authors.forename: S
authors.initials: S
authors.lastname: Takinami
authors.forename: T
authors.initials: T
authors.lastname: Uchida
authors.forename: Y
authors.initials: Y
authors.lastname: Nomura
authors.forename: J
authors.initials: J
authors.lastname: Mizoe
authors.forename: S
authors.initials: S
authors.lastname: Banik
authors.forename: K
authors.initials: K
authors.lastname: Tanimoto
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002356:Cartilage / Q000528:radiation effects; D002460:Cell Line; D002478:Cells, Cultured; D017931:DNA Primers; D005720:Gamma Rays; D015971:Gene Expression Regulation, Enzymologic / Q000528:radiation effects*; D008297:Male; D053509:Matrix Metalloproteinase 13 / Q000235:genetics*; D051379:Mice; D010006:Osteoblasts / Q000201:enzymology* / Q000528:radiation effects; D010315:Particle Accelerators; D016133:Polymerase Chain Reaction; D051381:Rats; D013977:Tibia / Q000201:enzymology* / Q000528:radiation effects
chemical_list: D017931:DNA Primers; D053509:Matrix Metalloproteinase 13