Influence of bisphosphonates on the osteoblast RANKL and OPG gene expression in vitro

• DOI: 10.1007/s00784-010-0477-8
• Publication Date: 2010-10-13T21:25:30Z
• Authors: Felix Peter Koch; Christina Merkel; Thomas Ziebart; Ralf Smeets; Christian Walter; Bilal Al-Nawas
• Keywords: 0301 basic medicine; Osteoblasts; Time Factors; Bone Density Conservation Agents; Diphosphonates; Dose-Response Relationship, Drug; Reverse Transcriptase Polymerase Chain Reaction; RANK Ligand; Cell Culture Techniques; Imidazoles; Osteoprotegerin; Real-Time Polymerase Chain Reaction; Zoledronic Acid; Cell Line; 03 medical and health sciences; Gene Expression Regulation; Humans; Clodronic Acid; Ibandronic Acid

Bisphosphonates are widely used in the clinical treatment of bone diseases with increased bone resorption. In terms of side effects, they are widely known to be associated with osteonecrosis of the jaw (BONJ). The objective of this study was to evaluate the effect of bisphosphonates on the gene expression of receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) in vitro. Nitrogen-containing and non-nitrogen containing bisphosphonates have been compared. Human osteoblasts were stimulated with zoledronate and ibandronate at concentrations of 5 × 10(-5) M, 5 × 10(-6) M, and 5 × 10(-7) M over the experimental period of 14 days. Furthermore, the hOB cell lines were stimulated by clodronate at concentrations of 5 × 10(-3) M, 5 × 10(-5) M, and 5 × 10(-6) M. At each point in time, the gene expression levels of RANKL and OPG were quantified by real-time RT-PCR. The results showed a moderate enhancement of OPG gene expression whereas RANKL gene expression was strongly increased by nitrogen-containing bisphosphonates reaching a maximum after 14 days at high concentrations of 5 × 10(-5) M. Lower concentrations did not enhance the RANKL and OPG expression considerably. The non-nitrogen-containing bisphosphonate clodronate, however, effected OPG and RANKL gene expression much less, even at higher concentrations of 5 × 10(-3) M. The above-mentioned data suggest an enhanced RANKL/OPG gene expression after stimulation by bisphosphonates. Interestingly, clodronate might have little influence on osteoblast/osteoclast interaction with respect to OPG and RANKL gene expression.