Nonhomologous End Joining Is More Important Than Proton Linear Energy Transfer in Dictating Cell Death

Scott J. Bright, David B. Flint, Sharmistha Chakraborty, Conor H. McFadden, David S. Yoon, Lawrence Bronk, Uwe Titt, Radhe Mohan, David R. Grosshans, Pavel Sumazin, Simona F. Shaitelman, Aroumougame Asaithamby, Gabriel O. Sawakuchi

Research output: Contribution to journalArticle

Abstract

Purpose: This study seeks to identify biological factors that may yield a therapeutic advantage of proton therapy versus photon therapy. Specifically, we address the role of nonhomologous end-joining (NHEJ) and homologous recombination (HR) in the survival of cells in response to clinical photon and proton beams. Methods and Materials: We irradiated HT1080, M059K (DNA-PKcs+/+), and HCC1937 human cancer cell lines and their isogenic counterparts HT1080-shDNA-PKcs, HT1080-shRAD51IND, M059J (DNA-PKcs–/–), and HCC1937-BRCA1 (BRCA1 complemented) to assess cell clonogenic survival and γ-H2AX radiation-induced foci. Cells were irradiated with either clinically relevant photons or 1 of 3 proton linear energy transfer (LET) values. Results: Our results indicate that NHEJ deficiency is more important in dictating cell survival than proton LET. Cells with disrupted HR through BRCA1 mutation showed increased radiosensitivity only for high-LET protons whereas RAD51 depletion showed increased radiosensitivity for both photons and protons. DNA double strand breaks, assessed by γ-H2AX radiation-induced foci, showed greater numbers after 24 hours in cells exposed to higher LET protons. We also observed that NHEJ-deficient cells were unable to repair the vast majority of double strand breaks after 24 hours. Conclusions: BRCA1 mutation significantly sensitizes cells to protons, but not photons. Loss of NHEJ renders cells hypersensitive to radiation, whereas the relative importance of HR increases with LET across several cell lines. This may be attributable to the more clustered damage induced by higher LET protons, which are harder to repair through NHEJ. This highlights the importance of tumor biology in dictating treatment modality and suggests BRCA1 as a potential biomarker for proton therapy response. Our data also support the use of pharmacologic inhibitors of DNA repair to enhance the sensitivity to different radiation types, although this raises issues for normal tissue toxicity.

Original languageEnglish (US)
JournalInternational Journal of Radiation Oncology Biology Physics
DOIs
StateAccepted/In press - Jan 1 2019

Fingerprint

Linear Energy Transfer
linear energy transfer (LET)
death
Protons
Cell Death
Photons
protons
Homologous Recombination
cells
Proton Therapy
Radiation
deoxyribonucleic acid
Cell Survival
Radiation Tolerance
therapy
photons
radiation tolerance
radiation
mutations
cultured cells

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

Cite this

Nonhomologous End Joining Is More Important Than Proton Linear Energy Transfer in Dictating Cell Death. / Bright, Scott J.; Flint, David B.; Chakraborty, Sharmistha; McFadden, Conor H.; Yoon, David S.; Bronk, Lawrence; Titt, Uwe; Mohan, Radhe; Grosshans, David R.; Sumazin, Pavel; Shaitelman, Simona F.; Asaithamby, Aroumougame; Sawakuchi, Gabriel O.

In: International Journal of Radiation Oncology Biology Physics, 01.01.2019.

Research output: Contribution to journalArticle

Bright, SJ, Flint, DB, Chakraborty, S, McFadden, CH, Yoon, DS, Bronk, L, Titt, U, Mohan, R, Grosshans, DR, Sumazin, P, Shaitelman, SF, Asaithamby, A & Sawakuchi, GO 2019, 'Nonhomologous End Joining Is More Important Than Proton Linear Energy Transfer in Dictating Cell Death', International Journal of Radiation Oncology Biology Physics. https://doi.org/10.1016/j.ijrobp.2019.08.011
Bright, Scott J. ; Flint, David B. ; Chakraborty, Sharmistha ; McFadden, Conor H. ; Yoon, David S. ; Bronk, Lawrence ; Titt, Uwe ; Mohan, Radhe ; Grosshans, David R. ; Sumazin, Pavel ; Shaitelman, Simona F. ; Asaithamby, Aroumougame ; Sawakuchi, Gabriel O. / Nonhomologous End Joining Is More Important Than Proton Linear Energy Transfer in Dictating Cell Death. In: International Journal of Radiation Oncology Biology Physics. 2019.
@article{9eb0ce025c964ec49cbc65e2bb37b4b4,
title = "Nonhomologous End Joining Is More Important Than Proton Linear Energy Transfer in Dictating Cell Death",
abstract = "Purpose: This study seeks to identify biological factors that may yield a therapeutic advantage of proton therapy versus photon therapy. Specifically, we address the role of nonhomologous end-joining (NHEJ) and homologous recombination (HR) in the survival of cells in response to clinical photon and proton beams. Methods and Materials: We irradiated HT1080, M059K (DNA-PKcs+/+), and HCC1937 human cancer cell lines and their isogenic counterparts HT1080-shDNA-PKcs, HT1080-shRAD51IND, M059J (DNA-PKcs–/–), and HCC1937-BRCA1 (BRCA1 complemented) to assess cell clonogenic survival and γ-H2AX radiation-induced foci. Cells were irradiated with either clinically relevant photons or 1 of 3 proton linear energy transfer (LET) values. Results: Our results indicate that NHEJ deficiency is more important in dictating cell survival than proton LET. Cells with disrupted HR through BRCA1 mutation showed increased radiosensitivity only for high-LET protons whereas RAD51 depletion showed increased radiosensitivity for both photons and protons. DNA double strand breaks, assessed by γ-H2AX radiation-induced foci, showed greater numbers after 24 hours in cells exposed to higher LET protons. We also observed that NHEJ-deficient cells were unable to repair the vast majority of double strand breaks after 24 hours. Conclusions: BRCA1 mutation significantly sensitizes cells to protons, but not photons. Loss of NHEJ renders cells hypersensitive to radiation, whereas the relative importance of HR increases with LET across several cell lines. This may be attributable to the more clustered damage induced by higher LET protons, which are harder to repair through NHEJ. This highlights the importance of tumor biology in dictating treatment modality and suggests BRCA1 as a potential biomarker for proton therapy response. Our data also support the use of pharmacologic inhibitors of DNA repair to enhance the sensitivity to different radiation types, although this raises issues for normal tissue toxicity.",
author = "Bright, {Scott J.} and Flint, {David B.} and Sharmistha Chakraborty and McFadden, {Conor H.} and Yoon, {David S.} and Lawrence Bronk and Uwe Titt and Radhe Mohan and Grosshans, {David R.} and Pavel Sumazin and Shaitelman, {Simona F.} and Aroumougame Asaithamby and Sawakuchi, {Gabriel O.}",
year = "2019",
month = "1",
day = "1",
doi = "10.1016/j.ijrobp.2019.08.011",
language = "English (US)",
journal = "International Journal of Radiation Oncology Biology Physics",
issn = "0360-3016",
publisher = "Elsevier Inc.",

}

TY - JOUR

T1 - Nonhomologous End Joining Is More Important Than Proton Linear Energy Transfer in Dictating Cell Death

AU - Bright, Scott J.

AU - Flint, David B.

AU - Chakraborty, Sharmistha

AU - McFadden, Conor H.

AU - Yoon, David S.

AU - Bronk, Lawrence

AU - Titt, Uwe

AU - Mohan, Radhe

AU - Grosshans, David R.

AU - Sumazin, Pavel

AU - Shaitelman, Simona F.

AU - Asaithamby, Aroumougame

AU - Sawakuchi, Gabriel O.

PY - 2019/1/1

Y1 - 2019/1/1

N2 - Purpose: This study seeks to identify biological factors that may yield a therapeutic advantage of proton therapy versus photon therapy. Specifically, we address the role of nonhomologous end-joining (NHEJ) and homologous recombination (HR) in the survival of cells in response to clinical photon and proton beams. Methods and Materials: We irradiated HT1080, M059K (DNA-PKcs+/+), and HCC1937 human cancer cell lines and their isogenic counterparts HT1080-shDNA-PKcs, HT1080-shRAD51IND, M059J (DNA-PKcs–/–), and HCC1937-BRCA1 (BRCA1 complemented) to assess cell clonogenic survival and γ-H2AX radiation-induced foci. Cells were irradiated with either clinically relevant photons or 1 of 3 proton linear energy transfer (LET) values. Results: Our results indicate that NHEJ deficiency is more important in dictating cell survival than proton LET. Cells with disrupted HR through BRCA1 mutation showed increased radiosensitivity only for high-LET protons whereas RAD51 depletion showed increased radiosensitivity for both photons and protons. DNA double strand breaks, assessed by γ-H2AX radiation-induced foci, showed greater numbers after 24 hours in cells exposed to higher LET protons. We also observed that NHEJ-deficient cells were unable to repair the vast majority of double strand breaks after 24 hours. Conclusions: BRCA1 mutation significantly sensitizes cells to protons, but not photons. Loss of NHEJ renders cells hypersensitive to radiation, whereas the relative importance of HR increases with LET across several cell lines. This may be attributable to the more clustered damage induced by higher LET protons, which are harder to repair through NHEJ. This highlights the importance of tumor biology in dictating treatment modality and suggests BRCA1 as a potential biomarker for proton therapy response. Our data also support the use of pharmacologic inhibitors of DNA repair to enhance the sensitivity to different radiation types, although this raises issues for normal tissue toxicity.

AB - Purpose: This study seeks to identify biological factors that may yield a therapeutic advantage of proton therapy versus photon therapy. Specifically, we address the role of nonhomologous end-joining (NHEJ) and homologous recombination (HR) in the survival of cells in response to clinical photon and proton beams. Methods and Materials: We irradiated HT1080, M059K (DNA-PKcs+/+), and HCC1937 human cancer cell lines and their isogenic counterparts HT1080-shDNA-PKcs, HT1080-shRAD51IND, M059J (DNA-PKcs–/–), and HCC1937-BRCA1 (BRCA1 complemented) to assess cell clonogenic survival and γ-H2AX radiation-induced foci. Cells were irradiated with either clinically relevant photons or 1 of 3 proton linear energy transfer (LET) values. Results: Our results indicate that NHEJ deficiency is more important in dictating cell survival than proton LET. Cells with disrupted HR through BRCA1 mutation showed increased radiosensitivity only for high-LET protons whereas RAD51 depletion showed increased radiosensitivity for both photons and protons. DNA double strand breaks, assessed by γ-H2AX radiation-induced foci, showed greater numbers after 24 hours in cells exposed to higher LET protons. We also observed that NHEJ-deficient cells were unable to repair the vast majority of double strand breaks after 24 hours. Conclusions: BRCA1 mutation significantly sensitizes cells to protons, but not photons. Loss of NHEJ renders cells hypersensitive to radiation, whereas the relative importance of HR increases with LET across several cell lines. This may be attributable to the more clustered damage induced by higher LET protons, which are harder to repair through NHEJ. This highlights the importance of tumor biology in dictating treatment modality and suggests BRCA1 as a potential biomarker for proton therapy response. Our data also support the use of pharmacologic inhibitors of DNA repair to enhance the sensitivity to different radiation types, although this raises issues for normal tissue toxicity.

UR - http://www.scopus.com/inward/record.url?scp=85072798772&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85072798772&partnerID=8YFLogxK

U2 - 10.1016/j.ijrobp.2019.08.011

DO - 10.1016/j.ijrobp.2019.08.011

M3 - Article

C2 - 31425731

AN - SCOPUS:85072798772

JO - International Journal of Radiation Oncology Biology Physics

JF - International Journal of Radiation Oncology Biology Physics

SN - 0360-3016

ER -