γ-H2AX as a marker for dose deposition in the brain of wistar rats after synchrotron microbeam radiation

PLoS One. 2015 Mar 23;10(3):e0119924. doi: 10.1371/journal.pone.0119924. eCollection 2015.

Abstract

Objective: Synchrotron radiation has shown high therapeutic potential in small animal models of malignant brain tumours. However, more studies are needed to understand the radiobiological effects caused by the delivery of high doses of spatially fractionated x-rays in tissue. The purpose of this study was to explore the use of the γ-H2AX antibody as a marker for dose deposition in the brain of rats after synchrotron microbeam radiation therapy (MRT).

Methods: Normal and tumour-bearing Wistar rats were exposed to 35, 70 or 350 Gy of MRT to their right cerebral hemisphere. The brains were extracted either at 4 or 8 hours after irradiation and immediately placed in formalin. Sections of paraffin-embedded tissue were incubated with anti γ-H2AX primary antibody.

Results: While the presence of the C6 glioma does not seem to modulate the formation of γ-H2AX in normal tissue, the irradiation dose and the recovery versus time are the most important factors affecting the development of γ-H2AX foci. Our results also suggest that doses of 350 Gy can trigger the release of bystander signals that significantly amplify the DNA damage caused by radiation and that the γ-H2AX biomarker does not only represent DNA damage produced by radiation, but also damage caused by bystander effects.

Conclusion: In conclusion, we suggest that the γ-H2AX foci should be used as biomarker for targeted and non-targeted DNA damage after synchrotron radiation rather than a tool to measure the actual physical doses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biomarkers / analysis*
  • Brain Neoplasms / metabolism
  • Brain Neoplasms / pathology*
  • Brain Neoplasms / radiotherapy
  • Bystander Effect / radiation effects*
  • DNA Damage / radiation effects*
  • Glioma / metabolism
  • Glioma / pathology*
  • Glioma / radiotherapy
  • Histones / metabolism*
  • Image Processing, Computer-Assisted
  • Immunoenzyme Techniques
  • Male
  • Phosphoproteins / metabolism*
  • Radiotherapy Dosage
  • Rats
  • Rats, Wistar
  • Synchrotrons*
  • Tumor Cells, Cultured
  • X-Rays / adverse effects*

Substances

  • Biomarkers
  • Histones
  • Phosphoproteins
  • gamma-H2AX protein, rat

Grants and funding

We acknowledge the European Synchrotron Radiation Facility (ESRF) for provision of beamtime and travel support. We would also like to acknowledge the financial support by the Canada Research Chairs programme; the Discovery Grants programme from the Natural Sciences and Engineering Research Council of Canada; the ESRF funded proposal MD 516; and the Innovative Methods in Radiotherapy and Radiosurgery using Synchrotron Radiation, which is part of the European Cooperation in Science and Technology (SYRA3 COST Action). Cristian Fernandez-Palomo’s PhD studies were funded by Becas Chile. E. Schültke holds a Marie Curie Reintegration Grant from the European Union (PIRG-GA-2010-268250). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.