Effect of omeprazole on the expression of transcription factors in osteoclasts and osteoblasts

Abstract

Abstract. The use of proton pump inhibitors (PPIs) seems to be related to increased fracture risk but the mechanism is unclear. In an effort to clarify the mechanism, we evaluated the effect of omeprazole, a representative of the PPIs, on the expression of transcription factors in osteoclasts and osteoblasts. Murine RAW264.7 and MC3T3-E1 cells were used for osteoclast and osteoblast analysis, to which various concentrations of omeprazole were added. RAW264.7 cells with ≥3 nuclei were considered tartrate-resistant acid phosphatase (TRAP)-positive, i.e. activated osteoclasts. Expressions of the calcitonin receptor (CTR), c-fos, nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1), and matrix metalloproteinase (MMP)-9 mRNA in osteoclasts were evaluated. Gene expression of osteocalcin and of the osteoprotegerin/receptor activator of NF-κB ligand (OPG/RANKL) ratio in osteoblasts was examined and Western blotting of NFATc1 was performed. Treating the osteoclasts with increasing doses of omeprazole did not affect TRAP positivity, but significantly decreased the expressions of CTR, c-fos, NFATc1, and MMP-9 regardless of the omeprazole concentration. The expression of osteocalcin and of the OPG/RANKL ratio in osteoblasts was augmented with increasing omeprazole concentrations. The result of the Western blot analysis with NFATc1 was similar to that of the expression of NFATc1 mRNA. Omeprazole decreased the activation of osteoclasts but increased that of osteoblasts in vitro, in part causing an osteopetrosis-like effect. Together with the effect of omeprazole on calcium homeostasis, increased fracture risk may be due to the osteopetrorickets-like effect of omeprazole.

Dose‐dependent inhibitory effects of proton pump inhibitors on human osteoclastic and osteoblastic cell activity

“…Therefore, the inhibitory effect of PPIs on ALP activity opens up the possibility of decreased mineralization, an effect that was observed in the present study. More recently, a study performed in murine MC3T3-E1 cells [21] showed that omeprazole, at 10 À5 M, increased the expression of osteocalcin and the osteoprotegerin/RANKL ratio, suggesting positive effects on osteoblastic behavior, and also the possibility of an indirect negative effect on osteoclastic differentiation mediated by osteoblastic cells [17]. In the present study, PPIs negatively affected human osteoblastic cells, but, as the cell culture systems were quite different, direct comparison is difficult.…”

“…This observation suggests that PPIs might induce direct nonspecific cytoxicity, which is further increased by specific inhibitory effects on selected functional parameters, namely osteoclastic resorption activity and the osteoblastic ability to form a mineralized matrix. It is worth noting that differential effects of PPIs on proliferation and functional parameters were also reported by Hyun et al ., who showed that, at ~ 10 −5 m , omeprazole did not interfere with cell viability/proliferation but affected osteoclastic and osteoblastic gene expression .…”

“…It was also reported that omeprazole inhibited 45 Ca 2+ release from neonatal mouse calvaria and significantly decreased the bone resorption activity of rat osteoclasts . Omeprazole was also shown to decrease the expression of transcription factors by murine RAW264.7 osteoclastic cells . In vivo , omeprazole and, especially, pantoprazole, when incorporated in implanted calcium phosphate‐based materials, decreased osteoclastic resorption activity , and the authors suggested that this effect might be regarded as potentially useful in bone regeneration strategies.…”

Pantoprazole, a Proton Pump Inhibitor, Delays Fracture Healing in Mice

“…In a previous study, Karsdal et al [22] demonstrated that the selective proton pump blocker bafilomycin completely inhibits osteoclastic bone resorption and even increases the number of osteoclasts. Also, Hyun et al [23] showed that the PPI omeprazole significantly increases the OPG/RANKL ratio without affecting TRAP positivity. This is in line with the results of the present study, demonstrating a pantoprazoleinduced increase of the OPG/RANKL ratio without affecting the number of TRAP-positive osteoclasts.…”

The ORF3 protein of porcine circovirus type 2 promotes secretion of IL-6 and IL-8 in porcine epithelial cells by facilitating proteasomal degradation of regulator of G protein signalling 16 through physical interaction

“…Pig IL-6 and IL-8 mRNA transcripts in PK15 cells were quantitatively measured by real-time PCR analyses as previously described (Hyun et al, 2010). The primer sequences used for each PCR are described in Table S1.…”