Repair Kinetics of DSB-Foci Induced by Proton and α-Particle Microbeams of Different Energies

Ana Belchior; João F Canhoto; Ulrich Giesen; Frank Langner; Hans Rabus; Reinhard Schulte

doi:10.3390/life12122040

Repair Kinetics of DSB-Foci Induced by Proton and α-Particle Microbeams of Different Energies

Life (Basel). 2022 Dec 6;12(12):2040. doi: 10.3390/life12122040.

Authors

Ana Belchior¹, João F Canhoto^{1

2}, Ulrich Giesen³, Frank Langner³, Hans Rabus⁴, Reinhard Schulte⁵

Affiliations

¹ Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS, Portugal.
² Departamento de Física, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
³ Physikalisch-Technische Bundesanstalt (PTB), 38116 Braunschweig, Germany.
⁴ Physikalisch-Technische Bundesanstalt (PTB), 10587 Berlin, Germany.
⁵ Division of Biomedical Engineering Sciences, Loma Linda University, Loma Linda, CA 92350, USA.

Abstract

In this work, the induction and repair of radiation-induced 53BP1 foci were studied in human umbilical vein endothelial cells irradiated at the PTB microbeam with protons and α-particles of different energies. The data were analyzed in terms of the mean number of 53BP1 foci induced by the different ion beams. The number of 53BP1 foci found at different times post-irradiation suggests that the disappearance of foci follows first order kinetics. The mean number of initially produced foci shows the expected increase with LET. The most interesting finding of this work is that the absolute number of persistent foci increases with LET but not their fraction. Furthermore, protons seem to produce more persistent foci as compared to α-particles of even higher LET. This may be seen as experimental evidence that protons may be more effective in producing severe DNA lesions, as was already shown in other work, and that LET may not be the best suited parameter to characterize radiation quality.

Keywords: DNA damage repair; radiation-induced foci; track structure.

Grants and funding

This work was partially funded by the Fundação para a Ciência e a Tecnologia (FCT) through the research grant PRT/BD/151544/2021 and by the research grant SIB06-REG3 of the European Metrology Research Program (EMRP) in the framework of the BioQuaRT project. The EMRP was jointly funded by the European Union and the EMRP-participating countries.