ERK signaling regulates RANKL expression induced by metal ions in MC3T3E1 murine calvarial preosteoblastic cells

Objective To investigate the effects on the expression of RANKL from osteoblasts(MC3T3E1)exposed to cobalt(Co2+)and chromium(Cr3+)ions and the effect of ERK-MAPK in the above process and to explore the methods of preventing the periprosthetic osteolysis.Methods Osteoblasts were cultured in vitro,in a density of 1×105 cells/ml,and divided into three groups according to the used culture solution.In control group(group A),osteoblasts were cultured with normal saline;in experimental group one(group B),osteoblasts were cultured with cobalt(Co2+)and chromium(Cr3+)ions solution;in experimental group two(group C),osteoblasts were cultured with Co2+,Cr3+ solution and inhibitor of ERK signaling(PD98059).The RT-PCR and ELISA methods were applied to detect the expression of RANKL mRNA and protein at 24 and 48 h after co-culture respectively.Results RT-PCR revealed that the gene expression of RANKL could be detected in three groups at 24 and 48 h after culture.The expression level of RANKL mRNA in groups B and C was higher than that in control A,and that in group C was decreased obviously as compared with that in group B(all P0.01).ELISA revealed that the expression of RANKL in experimental groups B and C was increased obviously as compared with that in control group,and as compared with group A,the RANKL was increased to 61.6-fold,44.4-fold respectively at 24 h and 13.8-fold,10.5-fold respectively at 48 h(all P0.01).After culture for 24 and 48 h,the expression of RANKL in group C was decreased obviously by 27.6% and 23.6% as compared with that in group B(P0.01).Conclusion Co2+ and Cr3+ ions could stimulate the expression of RANKL mRNA and the secretion of RANKL protein from osteoblasts.PD98059 could restrain the expression of RANKL at a certain degree and decrease the occurrence of the periprosthetic osteolysis.