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Archive > Volume 20 Issue 3 > 2013,20(3):278-283. DOI:10.3872/j.issn.1007-385X.2013.03.004 Prev Next
Basic Research
Silencing ATM by siRNA enhances the radiosensitization effect of CpG ODN 7909 on lung cancer A549 cells
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Abstract:
Objective:To explore the potentiation of silencing atxia-telangiectasia mutated (ATM) gene expression in the radiosensitization effect of cytosine-phophate-guanine oligodeoxynucleotide (CpG ODN) 7909 on non-small cell lung cancer A549 cell line. Methods: ATM-siRNA was transfected into A549 cells, and the expression of ATM protein in A549 cells was examined by Western blotting. A549 cells were randomly classified into six groups: control group, CpG group, X-ray (IR) group, CpG+IR group, ATM-siRNA+CpG+IR group and NC-siRNA+CpG+IR group. Cell colony rates were evaluated by colony formation assay. One-hit multi-target model and linear quadratic model, which generated the radiation dose survival curve of the A549 cells, were fitted with Graphpad prism 5.0 software, and the parameters, including D0, Dq, N, α/β and SF2 were applied to analyze radiation damage repair capacity of A549 cells. The apoptosis of A549 cells was analyzed by flow cytometry. Results: ATM-siRNA transfection remarkably inhibited the expression of ATM protein in A549 cells (P<001). X-ray radiation inhibited the colony formation capacity of A549 cells in a dose-dependent manner (P<0.05). Moreover, a further decrease of the colony formation capacity of A549 cells was found in CpG+IR radiation combined treatment group (P<0.01). With the transfection of ATM-siRNA, the colony formation capacity of CpG-treated A549 cells was further decreased (10 Gy, \[0.05±0.00\]% vs \[0.71±0.00\]%, P<0.01). Radiation damage dose survival curves demonstrated that the value of α/β was significantly increased (1.48 vs 0.97，P<005)and the radiation damage repair capability was significantly decreased in ATM-siRNA+CpG+IR group compared with CpG+IR group. The apoptotic rate was significantly increased in CpG+IR group compared with IR radiation group (\[9.18±016\]% vs \[6.56±0.33\]%, P<0.01). The apoptotic rate of A549 cells in ATM-siRNA+CpG+IR group was further increased (\[9.18±0.16\]% vs \[10.45±0.40\]%, P<0.05). Conclusion:Silencing expression of ATM by siRNA can enhance the radiosensitization effect of CpG ODN 7909 on A549 cells. ATM may serve as a potential target for gene therapy of lung cancer.
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Project Supported:
Project supported by the Science and Technology Innovation Foundation from the Jinshan District of Shanghai (No. 2010-316)
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