Analysis of copy number variations induced by ultrashort electron beam radiation in human leukocytes in vitro

Tigran Harutyunyan; Galina Hovhannisyan; Anzhela Sargsyan; Bagrat Grigoryan; Ahmed H Al-Rikabi; Anja Weise; Thomas Liehr; Rouben Aroutiounian

doi:10.1186/s13039-019-0433-5

Analysis of copy number variations induced by ultrashort electron beam radiation in human leukocytes in vitro

Mol Cytogenet. 2019 May 16:12:18. doi: 10.1186/s13039-019-0433-5. eCollection 2019.

Authors

Tigran Harutyunyan¹, Galina Hovhannisyan¹, Anzhela Sargsyan¹, Bagrat Grigoryan², Ahmed H Al-Rikabi³, Anja Weise³, Thomas Liehr³, Rouben Aroutiounian¹

Affiliations

¹ 1Department of Genetics and Cytology, Yerevan State University, 1 Alex Manoogian, 0025 Yerevan, Armenia.
² 2CANDLE Synchrotron Research Institute, Acharyan 31, 0040 Yerevan, Armenia.
³ Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, D-07740 Jena, Germany.

Abstract

Background: Environmental risk factors have been shown to alter DNA copy number variations (CNVs). Recently, CNVs have been described to arise after low-dose ionizing radiation in vitro and in vivo. Development of cost- and size-effective laser-driven electron accelerators (LDEAs), capable to deliver high energy beams in pico- or femtosecond durations requires examination of their biological effects. Here we studied in vitro impact of LDEAs radiation on known CNV hotspots in human peripheral blood lymphocytes on single cell level.

Results: Here CNVs in chromosomal regions 1p31.1, 7q11.22, 9q21.3, 10q21.1 and 16q23.1 earlier reported to be sensitive to ionizing radiation were analyzed using molecular cytogenetics. Irradiation of cells with 0.5, 1.5 and 3.0 Gy significantly increased signal intensities in all analyzed chromosomal regions compared to controls. The latter is suggested to be due to radiation-induced duplication or amplification of CNV stretches. As significantly lower gains in mean fluorescence intensities were observed only for chromosomal locus 1p31.1 (after irradiation with 3.0 Gy variant sensitivites of different loci to LDEA is suggested. Negative correlation was found between fluorescence intensities and chromosome size (r = - 0.783, p < 0.001) in cells exposed to 3.0 Gy irradiation and between fluorescence intensities and gene density (r = - 0.475, p < 0.05) in cells exposed to 0.5 Gy irradiation.

Conclusions: In this study we demonstrated that irradiation with laser-driven electron bunches can induce molecular-cytogenetically visible CNVs in human blood leukocytes in vitro. These CNVs occur most likely due to duplications or amplification and tend to inversely correlate with chromosome size and gene density. CNVs can last in cell population as stable chromosomal changes for several days after radiation exposure; therefore this endpoint can be used for characterization of genetic effects of accelerated electrons. These findings should be complemented with other studies and implementation of more sophisticated approaches for CNVs analysis.

Keywords: AREAL; Accelerated electrons; Chromosome size; Copy number variations (CNVs); Duplication; Gene density.