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Influence of bisphosphonates on the osteoblast RANKL and OPG gene expression in vitro
Felix Peter Koch1, Christina Merkel, Thomas Ziebart
1Department of Oral and Maxillofacial Surgery, University Medical Centre of Johannes Gutenberg University Mainz, Mainz, Germany. koch@mkg.klinik.uni-mainz.de
Abstract:
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.
Insights
Nitrogen-containing bisphosphonates significantly increase gene expression of RANKL and OPG in human osteoblasts, potentially impacting bone resorption. Non-nitrogen-containing bisphosphonates show minimal effects on these key bone remodeling factors.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Bisphosphonates are crucial for treating bone diseases characterized by high bone resorption.
- Osteonecrosis of the jaw (BONJ) is a known side effect associated with bisphosphonate therapy.
- Understanding bisphosphonate effects on bone remodeling markers is vital for patient safety and treatment efficacy.
Purpose of the Study:
- To investigate the in vitro effects of nitrogen-containing and non-nitrogen-containing bisphosphonates on the gene expression of RANKL and OPG in human osteoblasts.
- To compare the dose- and time-dependent responses of different bisphosphonate classes on key regulators of osteoclastogenesis.
Main Methods:
- Human osteoblasts (hOB) were treated with zoledronate and ibandronate (nitrogen-containing) or clodronate (non-nitrogen-containing) at various concentrations.
- Cells were cultured for 14 days, with gene expression of RANKL and OPG quantified using real-time RT-PCR at multiple time points.
- Comparative analysis of gene expression changes between different bisphosphonate types and concentrations was performed.
Main Results:
- Nitrogen-containing bisphosphonates (zoledronate, ibandronate) significantly upregulated RANKL gene expression, peaking at 14 days with high concentrations (5 × 10(-5) M).
- A moderate increase in OPG gene expression was observed with nitrogen-containing bisphosphonates.
- Clodronate demonstrated minimal impact on RANKL and OPG gene expression, even at high concentrations (5 × 10(-3) M).
Conclusions:
- Nitrogen-containing bisphosphonates enhance RANKL and OPG gene expression in human osteoblasts, suggesting a mechanism influencing osteoblast/osteoclast interactions.
- The differential effects highlight the importance of bisphosphonate chemical structure in modulating bone remodeling pathways.
- Clodronate appears to have a limited effect on RANKL/OPG expression, potentially indicating a lower risk for altering osteoblast/osteoclast communication compared to nitrogen-containing agents.
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