title: Different effects of carbon ion and gamma-irradiation on expression of receptor activator of NF-kB ligand in MC3T3-E1 osteoblast cells.
abstract: We investigated the effects of carbon ion and gamma-irradiation on osteoblastic MC3T3-E1 cells by comparing mRNA expression levels for RANKL and osteoprotegerin by RT-PCR. MC3T3-E1 cells were irradiated with 2, 4, or 6 Gy of carbon ions or gamma-rays, and total RNA was harvested 1, 2, 3, 5, or 7 days after irradiation. The RANKL mRNA/OPG mRNA ratio in carbon ion-irradiated MC3T3-E1 cells was lower, while in gamma-irradiated MC3T3-E1 cells this ratio was higher than in non-irradiated cells. To evaluate osteoclastogenesis of MC3T3-E1 cells, carbon ion- or gamma-irradiated cells were co-cultured with non-irradiated cells from murine bone marrow. Staining for tartrate-resistant acid phosphatase (TRAP) in co-cultures showed that carbon ion irradiation suppressed osteoclastogenesis. This result is consistent with the lower RANKL/OPG mRNA ratio for carbon ion-irradiated cells. These results suggest that carbon ion irradiation acts primarily on osteoblastic cells, leading to a decrease in the RANKL/OPG mRNA ratio. This effect, in turn, leads to a decrease in osteoclastogenesis and osteoclast activity, which results in an increase in bone volume.
authors.affiliation: Department of Oral and Maxillofacial Radiology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan. jiri@hiroshima-u.ac.jp
authors.forename: Masahiko
authors.initials: M
authors.lastname: Sawajiri
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nomura
authors.forename: Ujjal Kumar
authors.initials: UK
authors.lastname: Bhawal
authors.forename: Ryo
authors.initials: R
authors.lastname: Nishikiori
authors.forename: Masayuki
authors.initials: M
authors.lastname: Okazaki
authors.forename: Jun'etsu
authors.initials: J
authors.lastname: Mizoe
authors.forename: Keiji
authors.initials: K
authors.lastname: Tanimoto
mesh_terms: D000135:Acid Phosphatase / Q000096:biosynthesis; D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism; D002250:Carbon Radioisotopes; D002460:Cell Line; D018920:Coculture Techniques; D005720:Gamma Rays; D015870:Gene Expression / Q000528:radiation effects*; D007527:Isoenzymes / Q000096:biosynthesis; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D010006:Osteoblasts / Q000378:metabolism* / Q000528:radiation effects*; D053244:Osteoprotegerin / Q000096:biosynthesis*; D053245:RANK Ligand / Q000096:biosynthesis*; D000071681:Tartrate-Resistant Acid Phosphatase
chemical_list: D002250:Carbon Radioisotopes; D007527:Isoenzymes; D016328:NF-kappa B; D053244:Osteoprotegerin; D053245:RANK Ligand; C505689:Tnfsf11 protein, mouse; D000135:Acid Phosphatase; C000605511:Acp5 protein, mouse; D000071681:Tartrate-Resistant Acid Phosphatase