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Pulsed low dose-rate irradiation response in isogenic HNSCC cell lines with different radiosensitivity

Vesna Todorovic

Vesna Todorovic

Institute of Oncology Ljubljana, Department of Experimental OncologyLjubljana, Slovenia
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Todorovic, Vesna
, 
Ajda Prevc

Ajda Prevc

Institute of Oncology Ljubljana, Department of Experimental OncologyLjubljana, Slovenia
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Prevc, Ajda
, 
Martina Niksic Zakelj

Martina Niksic Zakelj

Institute of Oncology Ljubljana, Department of Experimental OncologyLjubljana, Slovenia
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Zakelj, Martina Niksic
, 
Monika Savarin

Monika Savarin

Institute of Oncology Ljubljana, Department of Experimental OncologyLjubljana, Slovenia
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Savarin, Monika
, 
Simon Bucek

Simon Bucek

Institute of Oncology Ljubljana, Department of CytopathologyLjubljana, Slovenia
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Bucek, Simon
, 
Blaz Groselj

Blaz Groselj

Institute of Oncology Ljubljana, Department of Radiation OncologyLjubljana, Slovenia
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Groselj, Blaz
, 
Primoz Strojan

Primoz Strojan

  • Institute of Oncology Ljubljana, Department of Radiation OncologyLjubljana, Slovenia
  • University of Ljubljana, Faculty of MedicineLjubljana, Slovenia
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Strojan, Primoz
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Maja Cemazar

Maja Cemazar

  • Institute of Oncology Ljubljana, Department of Experimental OncologyLjubljana, Slovenia
  • University of Primorska, Faculty of Health SciencesIzola, Slovenia
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Cemazar, Maja
 and 
Gregor Sersa

Gregor Sersa

  • Institute of Oncology Ljubljana, Department of Experimental OncologyLjubljana, Slovenia
  • University of Ljubljana, Faculty of Health SciencesLjubljana, Slovenia
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Sersa, Gregor
  
Mar 27, 2020
Pulsed low dose-rate irradiation response in isogenic HNSCC cell lines with different radiosensitivity's Cover Image
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Article Category: Research Article
Published Online: Mar 27, 2020
Page range: 168 - 179
Received: Feb 10, 2020
Accepted: Mar 01, 2020
DOI: https://doi.org/10.2478/raon-2020-0015
Keywords
© 2020 Vesna Todorovic, Ajda Prevc, Martina Niksic Zakelj, Monika Savarin, Simon Bucek, Blaz Groselj, Primoz Strojan, Maja Cemazar, Gregor Sersa, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Figure 1

Schematic diagram of irradiation schedule.
Schematic diagram of irradiation schedule.

Figure 2

Surviving fraction of parental FaDu and radioresistant FaDu-RR cells after exposure to low doses of ionizing radiation. Symbols are mean ± standard error of the mean from four independent experiments. * - significantly different from FaDu cells.
Surviving fraction of parental FaDu and radioresistant FaDu-RR cells after exposure to low doses of ionizing radiation. Symbols are mean ± standard error of the mean from four independent experiments. * - significantly different from FaDu cells.

Figure 3

Surviving fraction of parental FaDu and radioresistant FaDu-RR after exposure to different PLDR irradiation regimes. (A) Surviving fraction of parental FaDu cells after 7x0.3 Gy PLDR and (B) after 10x0.2 Gy PLDR irradiation. (C) Surviving fraction of radioresistant FaDu-RR cells after 7x0.3 Gy PLDR and (D) after 10x0.2 Gy PLDR irradiation. Bars present mean ± SEM from four independent experiments. ** = significantly different from 0 Gy and low dose IR (0.3 Gy or 0.2 Gy); * = significant difference between the groups; n. s. = non-significant difference.
Surviving fraction of parental FaDu and radioresistant FaDu-RR after exposure to different PLDR irradiation regimes. (A) Surviving fraction of parental FaDu cells after 7x0.3 Gy PLDR and (B) after 10x0.2 Gy PLDR irradiation. (C) Surviving fraction of radioresistant FaDu-RR cells after 7x0.3 Gy PLDR and (D) after 10x0.2 Gy PLDR irradiation. Bars present mean ± SEM from four independent experiments. ** = significantly different from 0 Gy and low dose IR (0.3 Gy or 0.2 Gy); * = significant difference between the groups; n. s. = non-significant difference.

Figure 4

Cell cycle distribution in parental FaDu and radioresistant FaDu-RR cells after exposure to different PLDR irradiation regimes. (A) Cell cycle distribution in FaDu cells 5 h and (B) 24 h after irradiation. (C) Cell cycle distribution in FaDu-RR cells 5 h and (D) 24 h after irradiation. Bars present mean ± SEM from four independent experiments. * = significantly different from 0 Gy; ** = significantly different from 0 Gy and 0.3 Gy; # = significantly different from 0 Gy, 0.3 Gy and 2.1 Gy; n. s. = non-significant difference.
Cell cycle distribution in parental FaDu and radioresistant FaDu-RR cells after exposure to different PLDR irradiation regimes. (A) Cell cycle distribution in FaDu cells 5 h and (B) 24 h after irradiation. (C) Cell cycle distribution in FaDu-RR cells 5 h and (D) 24 h after irradiation. Bars present mean ± SEM from four independent experiments. * = significantly different from 0 Gy; ** = significantly different from 0 Gy and 0.3 Gy; # = significantly different from 0 Gy, 0.3 Gy and 2.1 Gy; n. s. = non-significant difference.

Figure 5

Heat maps of DNA damage signalling gene expression in parental FaDu (A) and radioresistant FaDu-RR cells (B) in 0.3 Gy, 2.1 Gy and 7x0.3 Gy irradiated cells relative to the gene expression in control non-irradiated cells. The magnitude of the fold change in gene expression of each gene from three independent experiments is represented by the colour. Green indicates under-expressed genes, and red indicates over-expressed genes.
Heat maps of DNA damage signalling gene expression in parental FaDu (A) and radioresistant FaDu-RR cells (B) in 0.3 Gy, 2.1 Gy and 7x0.3 Gy irradiated cells relative to the gene expression in control non-irradiated cells. The magnitude of the fold change in gene expression of each gene from three independent experiments is represented by the colour. Green indicates under-expressed genes, and red indicates over-expressed genes.

Figure 6

DNA damage signalling gene expression in parental FaDu and radioresistant FaDu-RR cells in response to different irradiation protocols. (A) Gene expression of FaDu cells in response to 0.3 Gy, 2.1 Gy, and 7x0.3 Gy irradiation relative to the control non-irradiated FaDu cells. (B) Gene expression in FaDu-RR cells in response to 0.3 Gy, 2.1 Gy, and 7x0.3 Gy irradiation relative to the control non-irradiated FaDu-RR cells. Volcano plots show the fold change in gene expression and statistical significance (p value). The horizontal line shows the statistical significance threshold (p value < 0.05). Two vertical dashed lines show the threshold of over-expressed (right) and under-expressed genes (left), while the solid vertical line shows no change in gene expression. Symbols represent the mean gene expression of each tested gene in irradiated cells relative to control non-irradiated cells from three independent experiments.
DNA damage signalling gene expression in parental FaDu and radioresistant FaDu-RR cells in response to different irradiation protocols. (A) Gene expression of FaDu cells in response to 0.3 Gy, 2.1 Gy, and 7x0.3 Gy irradiation relative to the control non-irradiated FaDu cells. (B) Gene expression in FaDu-RR cells in response to 0.3 Gy, 2.1 Gy, and 7x0.3 Gy irradiation relative to the control non-irradiated FaDu-RR cells. Volcano plots show the fold change in gene expression and statistical significance (p value). The horizontal line shows the statistical significance threshold (p value < 0.05). Two vertical dashed lines show the threshold of over-expressed (right) and under-expressed genes (left), while the solid vertical line shows no change in gene expression. Symbols represent the mean gene expression of each tested gene in irradiated cells relative to control non-irradiated cells from three independent experiments.

Figure 7

Venn diagrams of DNA damage signalling gene expression in parental FaDu and radioresistant FaDu-RR cells showing overlapping and differential gene expression. Only genes significantly over-expressed or under-expressed relative to control non-irradiated cells are shown. Genes in bold red are over-expressed, genes in bold green are under-expressed.
Venn diagrams of DNA damage signalling gene expression in parental FaDu and radioresistant FaDu-RR cells showing overlapping and differential gene expression. Only genes significantly over-expressed or under-expressed relative to control non-irradiated cells are shown. Genes in bold red are over-expressed, genes in bold green are under-expressed.

Figure 8

Heat maps of DNA damage signalling gene expression in radioresistant FaDu-RR cells relative to the gene expression in parental FaDu cells. The magnitude of the fold change in gene expression of each gene from three independent experiments is represented by colour. Green indicates under-expressed genes, and red indicates over-expressed genes.
Heat maps of DNA damage signalling gene expression in radioresistant FaDu-RR cells relative to the gene expression in parental FaDu cells. The magnitude of the fold change in gene expression of each gene from three independent experiments is represented by colour. Green indicates under-expressed genes, and red indicates over-expressed genes.

Figure 9

DNA damage signalling gene expression in radioresistant FaDu-RR cells relative to parental FaDu. (A) Gene expression in control non-irradiated cells. (B) Gene expression in 0.3 Gy irradiated cells. (C) Gene expression in 2.1 Gy irradiated cells. (D) Gene expression in 7x0.3 Gy irradiated cells. Volcano plots show the fold change in gene expression in radioresistant FaDu-RR relative to parental FaDu cells and statistical significance (p value). The horizontal line shows the statistical significance threshold (p value < 0.05). Two vertical dashed lines show the threshold of over-expressed (right) and under-expressed genes (left), while the solid vertical line shows no change in gene expression. Symbols represent the mean gene expression of each tested gene in radioresistant FaDu-RR cells relative to parental FaDu cells from three independent experiments.
DNA damage signalling gene expression in radioresistant FaDu-RR cells relative to parental FaDu. (A) Gene expression in control non-irradiated cells. (B) Gene expression in 0.3 Gy irradiated cells. (C) Gene expression in 2.1 Gy irradiated cells. (D) Gene expression in 7x0.3 Gy irradiated cells. Volcano plots show the fold change in gene expression in radioresistant FaDu-RR relative to parental FaDu cells and statistical significance (p value). The horizontal line shows the statistical significance threshold (p value < 0.05). Two vertical dashed lines show the threshold of over-expressed (right) and under-expressed genes (left), while the solid vertical line shows no change in gene expression. Symbols represent the mean gene expression of each tested gene in radioresistant FaDu-RR cells relative to parental FaDu cells from three independent experiments.

Figure 10

Venn diagrams of DNA damage signalling gene expression in radioresistant FaDu-RR cells showing overlapping and different gene expression after different irradiation protocols relative to parental FaDu cells. Only genes significantly over-expressed or under-expressed relative to parental FaDu cells are shown. Gene in bold red is over-expressed, genes in bold green are under-expressed.
Venn diagrams of DNA damage signalling gene expression in radioresistant FaDu-RR cells showing overlapping and different gene expression after different irradiation protocols relative to parental FaDu cells. Only genes significantly over-expressed or under-expressed relative to parental FaDu cells are shown. Gene in bold red is over-expressed, genes in bold green are under-expressed.
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Medicine, Clinical Medicine, Internal Medicine, Haematology, Oncology, Radiology
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