TY - JOUR
T1 - Identification and characterization of a small inhibitory peptide that can target DNA-PKcs autophosphorylation and increase tumor radiosensitivity
AU - Sun, Xiaonan
AU - Yang, Chunying
AU - Liu, Hai
AU - Wang, Qi
AU - Wu, Shi Xiu
AU - Li, Xia
AU - Xie, Tian
AU - Brinkman, Kathryn L.
AU - Teh, Bin S.
AU - Butler, E. Brian
AU - Xu, Bo
AU - Zheng, Shu
PY - 2012/12/1
Y1 - 2012/12/1
N2 - Purpose: The DNA protein kinase catalytic subunit (DNA-PKcs) is one of the critical elements involved in the DNA damage repair process. Inhibition of DNA-PKcs results in hypersensitivity to ionizing radiation (IR); therefore, this approach has been explored to develop molecular targeted radiosensitizers. Here, we aimed to develop small inhibitory peptides that could specifically target DNA-PKcs autophosphorylation, a critical step for the enzymatic activation of the kinase in response to IR. Methods and Materials: We generated several small fusion peptides consisting of 2 functional domains, 1 an internalization domain and the other a DNA-PKcs autophosphorylation inhibitory domain. We characterized the internalization, toxicity, and radiosensitization activities of the fusion peptides. Furthermore, we studied the mechanisms of the inhibitory peptides on DNA-PKcs autophosphorylation and DNA repair. Results: We found that among several peptides, the biotin-labeled peptide 3 (BTW3) peptide, which targets DNA-PKcs threonine 2647 autophosphorylation, can abrogate IR-induced DNA-PKcs activation and cause prolonged γ-H2AX focus formation. We demonstrated that BTW3 exposure led to hypersensitivity to IR in DNA-PKcs-proficient cells but not in DNA-PKcs-deficient cells. Conclusions: The small inhibitory peptide BTW3 can specifically target DNA-PKcs autophosphorylation and enhance radiosensitivity; therefore, it can be further developed as a novel class of radiosensitizer.
AB - Purpose: The DNA protein kinase catalytic subunit (DNA-PKcs) is one of the critical elements involved in the DNA damage repair process. Inhibition of DNA-PKcs results in hypersensitivity to ionizing radiation (IR); therefore, this approach has been explored to develop molecular targeted radiosensitizers. Here, we aimed to develop small inhibitory peptides that could specifically target DNA-PKcs autophosphorylation, a critical step for the enzymatic activation of the kinase in response to IR. Methods and Materials: We generated several small fusion peptides consisting of 2 functional domains, 1 an internalization domain and the other a DNA-PKcs autophosphorylation inhibitory domain. We characterized the internalization, toxicity, and radiosensitization activities of the fusion peptides. Furthermore, we studied the mechanisms of the inhibitory peptides on DNA-PKcs autophosphorylation and DNA repair. Results: We found that among several peptides, the biotin-labeled peptide 3 (BTW3) peptide, which targets DNA-PKcs threonine 2647 autophosphorylation, can abrogate IR-induced DNA-PKcs activation and cause prolonged γ-H2AX focus formation. We demonstrated that BTW3 exposure led to hypersensitivity to IR in DNA-PKcs-proficient cells but not in DNA-PKcs-deficient cells. Conclusions: The small inhibitory peptide BTW3 can specifically target DNA-PKcs autophosphorylation and enhance radiosensitivity; therefore, it can be further developed as a novel class of radiosensitizer.
KW - DNA-PKcs
KW - Peptides
KW - Radiosensitivity
UR - http://www.scopus.com/inward/record.url?scp=84869115801&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84869115801&partnerID=8YFLogxK
U2 - 10.1016/j.ijrobp.2012.01.092
DO - 10.1016/j.ijrobp.2012.01.092
M3 - Article
C2 - 22592045
AN - SCOPUS:84869115801
VL - 84
SP - 1212
EP - 1219
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
SN - 0360-3016
IS - 5
ER -