title: The role of biosilica in the osteoprotegerin/RANKL ratio in human osteoblast-like cells.
abstract: Earlier studies have demonstrated that biosilica, synthesized by the enzyme silicatein, induces hydroxyapatite formation in osteoblast-like SaOS-2 cells. Here we study the effect of biosilica on the expressions of osteoprotegerin [OPG] and the receptor activator for NF-kappaB ligand [RANKL] in the SaOS-2 cell model. We show that during growth of SaOS-2 cells on biosiliceous matrices hydroxyapatite formation is induced, while syntheses of cartilaginous proteoglycans and sulfated glycosaminoglycans are down-regulated. Furthermore, quantitative real-time RT-PCR analysis revealed a strong time-depended increase in expression of OPG in biosilica exposed SaOS-2 cells while the steady-state expression level of RANKL remained unchanged. These results have been corroborated on the protein level by ELISA assays. Therefore, we propose that biosilica stimulated OPG synthesis in osteoblast-like cells counteracts those pathways that control RANKL expression and function (e.g. maturation of pre-osteoclasts and activation of osteoclasts). Hence, the data obtained in the present study reveal the considerable biomedical potential of biosilica for treatment and prophylaxis of osteoporotic disorders.
authors.affiliation: Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Wiens
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Wang
authors.forename: Heinz C
authors.initials: HC
authors.lastname: Schröder
authors.forename: Ute
authors.initials: U
authors.lastname: Kolb
authors.forename: Ute
authors.initials: U
authors.lastname: Schlossmacher
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ushijima
authors.forename: Werner E G
authors.initials: WE
authors.lastname: Müller
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D002403:Cathepsins / Q000235:genetics / Q000378:metabolism; D018929:Cell Culture Techniques; D002460:Cell Line; D005109:Extracellular Matrix / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008422:Materials Testing; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D053244:Osteoprotegerin / Q000235:genetics / Q000378:metabolism*; D053245:RANK Ligand / Q000235:genetics / Q000378:metabolism*; D012822:Silicon Dioxide / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001672:Biocompatible Materials; D053244:Osteoprotegerin; D053245:RANK Ligand; C112571:silicatein alpha; D012822:Silicon Dioxide; D002403:Cathepsins