title: CpG-ODN 7909 increases radiation sensitivity of radiation-resistant human lung adenocarcinoma cell line by overexpression of Toll-like receptor 9.
abstract: Radioresistance is one of the main reasons for the failure of radiotherapy in lung cancer. The aim of this study was to establish a radiation-resistant lung cancer cell line, to evaluate whether CpG oligodeoxyribonucleotide (CpG-ODN) 7909 could increase its radiosensitivity and to explore the relevant mechanisms. The radioresistant cell line, referred to as R-A549, was generated by reduplicative fractionated irradiation from the human lung adenocarcinoma cell line A549. The radioresistance of R-A549 cells were confirmed by the Cell Counting Kit-8 (CCK-8), cell viability assay, and clonogenic assay. Cell growth kinetics, morphological feature, and radiosensitivity were compared between the original A549 cells and R-A549 cells treated with or without CpG-ODN 7909 or radiation. To further explore the potential mechanisms of radiosensitivity, the cell cycle distributions and the expression of Toll-like receptor 9 (TLR-9) were examined by Western blot and flow cytometry. The R-A549 cell line was generated and its radioresistance was further confirmed. CpG-ODN 7909 was found to increase much more radiosensitivity of R-A549 cells under combined treatments with CpG-ODN 7909 and radiation compared with its control group without any treatments. They presented their respective D0 1.33 ± 0.20 Gy versus 1.76 ± 0.25 Gy with N 3.44 ± 1.01 versus 4.96 ± 0.32. Further, there was a larger cell population of R-A549 cells under combined treatment in the G2/M phase compared with the control group after treatment with CpG-ODN7909 or radiation alone at 24 and 48 hour. The expression level of TLR-9 in R-A549 cells was found higher than in A549 cells. These results suggested that CpG-ODN 7909 increased the radiosensitivity of R-A549 cells, which might be mediated via the upregulated TLR-9 and prolonged cell cycle arrest in the G2/M phase compared with A549 cells.
authors.affiliation: Department of Oncology, Jinshan Hospital, Fudan University, Shanghai, China.
authors.forename: Li
authors.initials: L
authors.lastname: Yan
authors.forename: Guoxiong
authors.initials: G
authors.lastname: Xu
authors.forename: Tiankui
authors.initials: T
authors.lastname: Qiao
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Sujuan
authors.initials: S
authors.lastname: Yuan
authors.forename: Xuan
authors.initials: X
authors.lastname: Li
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy*; D000077192:Adenocarcinoma of Lung; D048708:Cell Growth Processes / Q000187:drug effects / Q000528:radiation effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy*; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology*; D011829:Radiation Dosage; D011836:Radiation Tolerance / Q000187:drug effects; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D016019:Survival Analysis
chemical_list: C408982:CPG-oligonucleotide; D009838:Oligodeoxyribonucleotides; D011838:Radiation-Sensitizing Agents