PD98059 Inhibits the Proliferation and Differentiation of Osteoblasts in Rat Otocyst / 听力学及言语疾病杂志

ABSTRACT

Objective To investigate the effect of ERK inhibitor PD98059 on the proliferation and differentia-tion of rat otocyst osteoblasts.Methods SD neonatal rat osteoblasts were extracted by two-step digestion with 0.25％pancreatin and type Ⅰ collagenase,and co-cultured with ERK inhibitor PD98059 at concentrations of 0 μmol/L,10 μmol/L,25 μmol/L and 50 μmol/L,respectively.Then,the osteoblasts proliferation of the four groups were assessed by EDU method for 4 consecutive days.The proliferation trend of each group was compared and analyzed.Osteoblasts were differentiated by β-sodium glycerophosphate,L-vitamin C and dexamethasone at concentrations of 10 mmol/L,50 ug/ml and 10-7 mol/L.After 24 h,the mRNA expression levels of osteogenic fac-tors which include Ocn,Bsp,Runx2,Bmp2,OPG and RANKL in each group were detected by RT-qPCR,and the differences of the results were analyzed.Results All the concentrations of ERK inhibitor PD98059 could inhibit the proliferation of osteoblasts in SD neonatal rat,and the inhibitory effect of PD98059 at concentrations of 10 μmol/L was significantly greater than that of the other three groups(P＜0.05).In addition,all the concentrations of PD98059 could inhibit the expressions of Ocn,Bsp,Runx2,Bmp2 and OPG mRNA.The mRNA expressions of Ocn,Bsp,Runx2 and Bmp2 in 10 μmol/L PD98059 group were significantly lower than those in 0 μmol/L,25μmol/L and 50 μmol/L PD98059 groups(P＜0.05).The mRNA expressions of OPG in 10 and 25 μmol/L PD98059 groups were significantly lower than those in 0 and 50 μmol/L PD98059 groups(P＜0.05),and there was no significant difference between the first two groups(P＞0.05).The CT value of RANKL mRNA was not detec-ted in all groups.Conclusion ERK pathway inhibitor PD98059 can both inhibit the proliferation and differentiation of osteoblasts in rat otocyst.Therefore,we speculate that ERK1/2-MAPK pathway may mediate the formation of tympanosclerosis by affecting the proliferation and differentiation of rat otocyst osteoblasts.