DNA damage in blood leukocytes from mice irradiated with accelerated carbon ions with an energy of 450 MeV/nucleon

Abstract

Purpose

The objective of the study was to estimate the DNA damage in blood leukocytes at long terms after irradiation of mice with carbon ions (450 MeV/nucleon) both before and in the Bragg peak.

Materials and methods

White outbred SHK male mice were exposed to whole-body irradiation with carbon ions at doses of 0.1–2 Gy in the spread-out Bragg peak and at a dose of 6 Gy before and in the Bragg peak. At different times after irradiation (1–75 days), whole blood was collected from the tail of each mouse and analyzed by the comet assay. Mice X-irradiated in the same dose range served as a positive control. The level of the expression of mRNA of CDKN1A, APEX1, BBC3, TXN2, and β-ACT genes in bone marrow cells was determined in animals irradiated with carbon ions at doses of 0.1–2 Gy using the real-time PCR.

Results

It was found that, 24 h after ¹²C-irradiation, a dose-dependent (0.1–2 Gy) increase in the DNA damage of leukocytes occurred, which was accompanied by a decrease in their concentration and an increase in the expression of the CDKN1A and BBC3 genes in bone marrow cells. The expression of the APEX1 and TXN2 genes did not change. In mice ¹²C-irradiated at a dose of 6 Gy before and in the Bragg peak, the level of DNA damage changed as follows: by day 3, it increased; by day 23 it returned to the control level; by day 30, it increased again; and by day 75, it fell to the control level on irradiation before the Bragg peak and was significantly higher (p < .05) than in the control after irradiation in the Bragg peak.

Conclusions

The dynamics of changes in the level of DNA damage in leucocytes of ¹²C-irradiated mice within 30 days is similar to that in mice exposed to sublethal doses of X-radiation. The retention of the high level of DNA damage by day 75 after ¹²C-irradiation in the Bragg peak indicates a significant injury of cells from different cell pools of the blood system. The high level of DNA damage may be related not only to complex DNA injuries but also to chronic oxidative stress.

Keywords:

• Accelerated carbon ions
• X-irradiation
• DNA damage
• the comet assay
• murine blood cells
• murine bone marrow cells

Acknowledgements

The authors are grateful to Dr. Sci. Prof. A. I. Gaziev for the discussion of the results and S. P. Romanchenko for helping in conducting the experiments.

Disclosure statement

The authors declare that they have no conflict of interest.

Research involving animal participants

All applicable international, national, and/or institutional guidelines for the care and use of animals were followed.

Additional information

Notes on contributors

Elena A. Kuznetsova

Elena A. Kuznetsova, PhD, is a Head of the Laboratory of Radiation Molecular Biology, Institute of Theoretical and Experimental Biophysics RAS, Pushchino, Moscow region, Russia.

Nikolay P. Sirota

Nikolay P. Sirota is a Senior Researcher at the Laboratory of Radiation Molecular Biology, Institute of Theoretical and Experimental Biophysics RAS, Pushchino, Moscow region, Russia.

Irina Yu. Mitroshina

Irina Yu. Mitroshina, PhD, is a Researcher at the Laboratory of Radiation Molecular Biology, Institute of Theoretical and Experimental Biophysics RAS, Pushchino, Moscow region, Russia.

Vladimir A. Pikalov

Vladimir A. Pikalov is a Lead Engineer at the Department of the accelerator complex Institute for High Energy Physics named by A.A. Logunov of National Research Centre «Kurchatov Institute», Protvino, Moscow region, Russia.

Elena N. Smirnova

Elena N. Smirnova is a Senior Researcher at the Laboratory of cell engineering, Institute of Theoretical and Experimental Biophysics RAS, Pushchino, Moscow region, Russia.

Olga M. Rozanova

Olga M. Rozanova is a Senior Researcher of Laboratory of cell engineering, Institute of Theoretical and Experimental Biophysics RAS, Pushchino, Moscow region, Russia.

Sergei I. Glukhov

Sergei I. Glukhov, PhD, is a Researcher at the Laboratory of Radiation Molecular Biology, Institute of Theoretical and Experimental Biophysics RAS, Pushchino, Moscow region, Russia.

Tatyana V. Sirota

Tatyana V. Sirota, PhD, is a Senior Researcher at the Laboratory of Biological Systems Energetics, Institute of Theoretical and Experimental Biophysics RAS, Pushchino, Moscow region, Russia.

Svetlana I. Zaichkina

Svetlana I. Zaichkina, PhD, is a Leading Researcher at the Laboratory of cell engineering, Institute of Theoretical and Experimental Biophysics RAS, Pushchino, Moscow region, Russia.