Study Of Mechanism Of Action Of Specific Inhibitor Of Cox-2 On Egr-1

Background: Primary bronchiogenic cancer , also called lung cancer, which is one of the most malignant tumor in adult male,threats the people'lives severely. The early diagnosis and therapy of lung cancer have improved obviously with the deep study, but the survival rates of five years did not raised significantly. The genesis and development of lung cancer is the process of gradual evolution which connected with the activation of proto-oncogene and the inactivation of anti-oncogene with the development of molecular biology and the study of pathogenesis. The dysfunction of Egr-1, which is one of the anti-oncogene, was close correlation to the development of many tumors included lung cancer, and have certified that Egr-1 produced a marked effect through the inhibition of proliferation and the induction of apoptosis of tumor cells. COX-2 not only participates in inflammatory reaction but also expresses more or less in kinds of malignant tumors, and much of early clinical experiment have confirmed that it plays a important part of the genesis, development, metastasis and prognosis of lung cancer through many mechanisms. So COX-2 becomes the new target to treat lung cancer on the molecular level. In and out of China, it has been reported that the specific inhibitor of COX-2 can inhibit the proliferation of lung cancer cells in vivo and vitro and can up-regulate the express of EGR-1 to induce apoptosis of tumor cells. But the precise molecular mechanism is not clear.Objective: To study the effects of specific inhibitor of COX-2 celecoxib in different concentration on cell apoptosis, cell cycle and expression of EGR-1 of A549 cells, and to investigate the molecular mechanism on the effects of anti-tumor.Method: A549 cells were cultured in vitro. The MTT assay was used to choose the best concentration of celecoxib. A549 cells were treated by 25.0μmol/L,50.0μmol/L and 100.0μmol/L celecoxib. Then the TUNEL assay was used to detect apoptosis, FCM assay was used to determine cell cycle, and RT-PCR assay was performed to evaluate the Egr-1 and Fas mRNA expression levels.Results: Treated by celecoxib in the concentration of 25.0μmol/L,50.0μmol/L and 100.0μmol/L, the rates of inhibitory proliferation of A549 cells were (9.9±1.1)%,(17.2±1.8)%,(25.7±2.2)% respectively, the rates of apoptosis of A549 cells were (8.82±0.34)% , (16.53±0.76)% and (23.31±0.58)% respectively, the apoptotic index of A549 cells were (10.67±1.46)%, (18.83±2.54)% and (25.67±2.10)% respectively,and the expression levels of Egr-1 and Fas mRNA were up-regulation synchronously. Conclusion: celecoxib,specific inhibitor of COX-2,can inhibit the proliferation of A549 cells by regulating the cell cycle and inducing the cell apoptosis. The molecular mechanism may be that COX-2 inhibitor up-regulate the expression of Fas by up-regulating the expression of Egr-1, and then induce the cell apoptosis by blocking the A549 cells in G0/G1 period.