Effects of hypoxia/radiation dual-sensitive promoter-Smac plasmid combined with X-rays irradiation on proliferation of hypoxic A549 cells

Abstract

Objective To construct recombinant expression vector of Smac gene mediated by hypoxia/radiation dual-sensitive promoter (HRE/Egrl),and observe the expression characteristics in A549 cells under normoxic and hypoxic conditions after transfection,and the inhibitory effects on proliferation under hypoxic condition.Methods The plasmid pcDNA3.1-Egrl-Smac and pcDNA3.1-HRE/Egrl-Smac were successfully constructed,and transfected into A549 cells.The expression levels of mRNA and protein were detected by using real-time quantitative polymerase chain reaction (Real-time PCR) and Western blotting,respectively.Cell proliferation changes were measured by methyl thiazol tetrazolium (MTT) as-say.Results Under normoxic condition,as compared with control group,Smac mRNA was significantly increased in A549 cells irradiated with 2 Gy or transfected and irradiated with 2 Gy (P ＜ 0.05).Hypoxia could significantly enhance the effects (P ＜ 0.05).At the same time,Smac protein had similar expression characteristics.Under normoxic and hypoxic conditions,at the same time point,as compared with control group,proliferation was significantly decreased in A549 cells irradiated with 2 Gy or transfected and irradiated with 2 Gy (P ＜ 0.05),and proliferation in each group under hypoxic condition was more lower than that in each group under normoxic condition (P ＜ 0.05).Conclusion Both hypoxia and radiation could enhance the Smac expression in A549 cells,and combination of hypoxia and 2 Gy irradiation could significantly inhibit proliferation of A549 cells. Key words: X-rays ; Hypoxia; Lung adenocarcinoma; Proliferation