Effects of Extracellular Signal Regulated Kinase Signaling Pathway on Cell Cycle of Airway Smooth Muscle Cells in Asthmatic Rats

Objective To investigate the effects of extracellular signal regulated kinase(ERK) signaling pathway on cell cycle of airway smooth muscle cells(ASMCs) in asthmatic rats.Methods Thirty Wistar rats were randomly assigned to a control group and an asthma group(15 rats in each group).Asthma model was established by ovalbumim sensitization and challenge.ASMC were isolated and cultured in vitro.The ASMCs from the asthmatic rats were treated with ERK activator epidermal growth factor (EGF) and inhibitor PD98059,respectively.The expressions of cyclin D1 and CDK2 in ASMCs were detected by immunocytochemical staining.The expressions of ERK1/2 and p-ERK1/2 protein were observed by western blotting for measurement of ERK activation rate.Results Compared with the control group[54.17±6.11,61.04±4.09,(49.91±3.26)%,respectively],the expressions of cyclin D1 protein and CDK2 protein,and the rate of ERK activation of ASMCs from the asthmatic rats significantly increased[76.15±4.88,92.30±7.95,(82.37±5.78)%,respectively] (P0.05).Furthermore,compared with those before treatment,the expression of cyclin D1 and CDK2,and the rate of ERK activation of ASMCs significantly decreased after treatment with PD98059 [58.78±4.60,69.15±5.83,(54.01±4.12)%,respectively](P0.05),and significantly increased after treatment with EGF[119.28±8.14,134.77±9.26,(91.57±5.32)%,respectively](P0.05).Conclusion ERK1/2 participates in proliferation regulation of ASMCs in asthma by enhancing the expressions of cyclin D1 and CDK2,which promotes quiescent cells into S phase.