Role Of Extracellular Signal-regulated Kinase On Human Lung Cancer Cells After CD40 Stimulation

Objective To observe the expression of p-ERK on lung cancer cells before or after CD40 stimulation ,and study the effect of extracellular signal-regulated kinase on proliferation of human lung cancer cells after CD40 stimulation.Methods Human lung cancer cells H460 were chosen as target cells and CD40 signal was stimulated by agonistic CD40 monoclonal antibody (5C11). MTT assay method was used to determine the proliferation of tumor cells which were treated with 5C11,PD98059 (an inhibitor of MEK1), and their combination. Immunofluorescence technique and flow cytometry were used to monitor changes of cell surface molecules, cell cycle, as well as cell apoptosis. Western blot analysis was used to examine the expression of p-ERK1/2.Results (1)After CD40 stimulation,CD40 positive cells H460 proliferation were suppressed(p<0.05), and an increase of inhibition was confirmed when they were pretreated with PD98059(p<0.05).(2)After CD40 stimulation, the number of cells entering G1 phase was increased compared with that in the control group(p<0.05),the same effect would be observed when they were treated with PD98059(p<0.05).When cells were treated with their combination,there was not significantly different from that of group 5C11 and group PD98059. The number of cells entering S phase was decreased. (3) No significant cell apoptosis was observed after 72-hour CD40 stimulation(p>0.05).However,when the cells were pretreated with PD98059,cell apoptosis was noted(p<0.05).(4) ERK activity increased and reached the peak at 30 min after treatment with 5C11 and decreased in PD98059 pretreated group.(5) After CD40 stimulation,the expression of cell surface molecule TNFRâ… was higher than it in the control group(p<0.05),while the expression of TNFRâ…¡was lower than it in the control group(p<0.05).Conclusion Stimulation of CD40 could enhance ERK1/2 activity,inhibition of this signal pathway might upregulate the susceptibility of lung cancer cells to agonistic CD40 monoclonal antibody induced suppression of proliferation.