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Impact of CHK2-small interfering RNA on CpG ODN7909-enhanced radiosensitivity in lung cancer A549 cells

Authors Chen W, Liu X, Qiao T, Yuan S

Received 18 September 2012

Accepted for publication 30 October 2012

Published 3 December 2012 Volume 2012:5 Pages 425—431

DOI https://doi.org/10.2147/OTT.S38240

Checked for plagiarism Yes

Review by Single-blind

Peer reviewer comments 2

Wei Chen,* Xiaoqun Liu,* Tiankui Qiao, Sujuan Yuan

Department of Oncology, Jinshan Hospital, Fudan University, Shanghai, People's Republic of China

*These authors contributed equally to this work

Objective: To investigate the impact of checkpoint kinase 2 (CHK2)-small interfering RNA (CHK2-siRNA) on the enhancement of radiosensitivity by CpG oligodeoxynucleotide (ODN) 7909 in lung cancer A549 cells.
Methods: The A549 cells were randomly divided into five groups: control, CpG, X-ray, CpG + X-ray, and CHK2-siRNA + CpG + X-ray. Cell colonization was observed using inverted microscopy. Cell cycle and apoptosis were analyzed by flow cytometry. CHK2 expression was detected by Western blot. CHK2-siRNA was adopted to silence the expression of CHK2.
Results: The level of CHK2 phosphorylation was higher in the CpG + X-ray group than in the X-ray group. Increases in G2/mitotic (M) phase arrest and apoptosis and a decrease of cell survival rate in the CpG + X-ray group were statistically significant (P < 0.05) when compared with the CHK2-siRNA + CpG + X-ray group in which the expression of CHK2 was obviously inhibited. The combination of CpG ODN7909 and X-ray irradiation was found to enhance the mitotic death of A549 cells. The sensitization enhancement ratio of mean death dose (D0) was 1.42 in the CpG + X-ray group, which was higher than that of the CHK2-siRNA + CpG + X-ray group, in which D0 was 1.05.
Conclusion: To a certain extent, the impact of a combination of CpG ODN7909 and X-ray on G2/M phase arrest, apoptosis, and rate of cell survival was attenuated by CHK2-siRNA in human lung adenocarcinoma A549 cells, indicating that increased phosphorylation of CHK2 might be a radiosensitive pathway.

Keywords: oligodeoxynucleotide, checkpoint kinase 2, mitotic death, apoptosis, X-ray

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