Accumulation of DNA Double-Strand Breaks in Normal Tissues After Fractionated Irradiation

Journal Article · Mon Mar 15 00:00:00 EDT 2010 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2009.10.009· OSTI ID:21372182

Fricke, Andreas; Wendorf, Juliane; Stuetzel, Annika; Kuehne, Martin ^[1]; Ong, Mei Fang ^[2]; Lipp, Peter ^[3]; Ruebe, Christian ^[1]

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1. Department of Radiation Oncology, Saarland University, Homburg/Saar (Germany)
2. Institute of Medical Biometrics, Epidemiology and Medical Informatics, Saarland University, Homburg/Saar (Germany)
3. Institute for Molecular Cell Biology, Saarland University, Homburg/Saar (Germany)

Purpose: There is increasing evidence that genetic factors regulating the recognition and/or repair of DNA double-strand breaks (DSBs) are responsible for differences in radiosensitivity among patients. Genetically defined DSB repair capacities are supposed to determine patients' individual susceptibility to develop adverse normal tissue reactions after radiotherapy. In a preclinical murine model, we analyzed the impact of different DSB repair capacities on the cumulative DNA damage in normal tissues during the course of fractionated irradiation. Material and Methods: Different strains of mice with defined genetic backgrounds (SCID{sup -/-} homozygous, ATM{sup -/-} homozygous, ATM{sup +/-}heterozygous, and ATM{sup +/+}wild-type mice) were subjected to single (2 Gy) or fractionated irradiation (5 x 2 Gy). By enumerating gammaH2AX foci, the formation and rejoining of DSBs were analyzed in organs representative of both early-responding (small intestine) and late-responding tissues (lung, kidney, and heart). Results: In repair-deficient SCID{sup -/-} and ATM{sup -/-}homozygous mice, large proportions of radiation-induced DSBs remained unrepaired after each fraction, leading to the pronounced accumulation of residual DNA damage after fractionated irradiation, similarly visible in early- and late-responding tissues. The slight DSB repair impairment of ATM{sup +/-}heterozygous mice was not detectable after single-dose irradiation but resulted in a significant increase in unrepaired DSBs during the fractionated irradiation scheme. Conclusions: Radiation-induced DSBs accumulate similarly in acute- and late-responding tissues during fractionated irradiation, whereas the whole extent of residual DNA damage depends decisively on the underlying genetically defined DSB repair capacity. Moreover, our data indicate that even minor impairments in DSB repair lead to exceeding DNA damage accumulation during fractionated irradiation and thus may have a significant impact on normal tissue responses in clinical radiotherapy.

• OSTI ID: 21372182
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Vol. 76, Issue 4; Other Information: DOI: 10.1016/j.ijrobp.2009.10.009; PII: S0360-3016(09)03342-2; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
DNA REPAIR
FRACTIONATED IRRADIATION
HEART
KIDNEYS
LUNGS
MICE
RADIOSENSITIVITY
RADIOTHERAPY
SMALL INTESTINE
STRAND BREAKS
ANIMALS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
BODY
CARDIOVASCULAR SYSTEM
DIGESTIVE SYSTEM
DNA DAMAGES
GASTROINTESTINAL TRACT
INTESTINES
IRRADIATION
MAMMALS
MEDICINE
NUCLEAR MEDICINE
ORGANS
RADIOLOGY
REPAIR
RESPIRATORY SYSTEM
RODENTS
SENSITIVITY
THERAPY
VERTEBRATES