Insulin effect on RANKL and OPG expression in human osteoblast-like MG63 cells

Authors: HUIXIN WANG, XIAOHUAN ZHONG

Abstract: To investigate the effect of insulin on receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG) expression in human osteosarcoma MG63 cells using real-time polymerase chain reaction. Materials and methods: MG63 cells were exposed to different concentrations of human recombinant insulin (1, 10, and 100 nM) for 24 h, and then the expression of RANKL and OPG mRNA was identified. After that, MG63 cells were exposed to tensile stress combined with 0 or 10 nM insulin respectively for 0, 3, 6, and 12 h, and then the expression of RANKL and OPG mRNA was identified. Human monocytes were cultured with the collected culture media from MG63 cells plates that were exposed to different concentrations of human recombinant insulin (0 and 10 nM) for 7 days, and then were stained with an acid phosphatase kit. Results: After 24 h of treatment with 1, 10, and 100 nM doses of insulin, the expression of RANKL and OPG mRNA was suppressed (P < 0.05), and the ratio of OPG to RANKL also was suppressed (P < 0.05). Application of tensile stress to MG63 cells induced a decrease in RANKL mRNA expression and an increase in OPG mRNA expression at 6 and 12 h (P < 0.05); 10 nM insulin decreased the mechanical stress-induced RANKL and OPG mRNA expression in MG63 cells at 6 and 12 h (P < 0.05). The ratio of OPG to RANKL increased at 6 and 12 h in the 2 groups (P < 0.05), but insulin decreased the mechanical stress-induced OPG/RANKL ratio at 12 h (P < 0.05). For the group of monocytes cultured with DMEM collected from MG63 cells plates that were cultured with 0 nM human recombinant insulin, osteoclast formation was not observed. Osteoclast formation was observed in monocytes cultured with DMEM collected from MG63 cells plates that were cultured with 10 nM human recombinant insulin. Conclusion: These results suggest that insulin can modulate osteoclast differentiation via altering the OPG and RANKL expression in osteoblasts. The deficiency in insulin may decrease the number of osteoclasts and osteoclast-mediated bone resorption in patients with type 1 diabetes mellitus.

Keywords: Insulin, MG63, OPG, RANKL, mechanical stimulus

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