Effects of High-Dose Ionizing Radiation in Human Gene Expression: A Meta-Analysis

• Published in: International journal of molecular sciences 2020-03, Vol.21 (6), p.1938
• Main Authors: Kanakoglou, Dimitrios S, Michalettou, Theodora-Dafni, Vasileiou, Christina, Gioukakis, Evangelos, Maneta, Dorothea, Kyriakidis, Konstantinos V, Georgakilas, Alexandros G, Michalopoulos, Ioannis
• Format: Article
• Language: English
• Subjects: Apoptosis; Biological activity; Cancer; Cell activation; Cell cycle; Cell Cycle Checkpoints - radiation effects; Cell death; Circadian rhythms; Datasets; Deoxyribonucleic acid; differential gene expression; DNA; DNA damage; DNA Damage - radiation effects; dna damage response; DNA repair; DNA Repair - radiation effects; Dose-Response Relationship, Radiation; Down-Regulation - radiation effects; Gene expression; Gene Expression - radiation effects; Gene Expression Profiling - methods; Genes; high-dose ionizing radiation; Human tissues; Humans; Ionizing radiation; Mapping; Meta-analysis; Nuclear accidents & safety; Nucleotide excision repair; Nucleotides; Oxidative stress; p53 Protein; Proteins; Quality control; Radiation dosage; Radiation, Ionizing; Repair; rna-seq; Signal transduction; Toxicity; Transcription activation; Transcriptomics; Up-Regulation - radiation effects
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms21061938

The use of high-dose Ionizing Radiation (IR) is currently one of the most common modalities in treatment of many types of cancer. The objective of this work was to investigate the effects of high-dose ionizing radiation on healthy human tissue, utilizing quantitative analysis of gene expression. To this end, publicly available transcriptomics datasets from human samples irradiated with a high dose of radiation and non-irradiated (control) ones were selected, and gene expression was determined using RNA-Seq data analysis. Raw data from these studies were subjected to quality control and trimming. Mapping of RNA-Seq reads was performed by the partial selective alignment method, and differential gene expression analysis was conducted. Subsequently, a meta-analysis was performed to select differentially expressed genes across datasets. Based on the differentially expressed genes discovered by meta-analysis, we constructed a protein-to-protein interaction network, and we identified biological pathways and processes related to high-dose IR effects. Our findings suggest that cell cycle arrest is activated, supported by our top down-regulated genes associated with cell cycle activation. DNA repair genes are down-regulated in their majority. However, several genes implicated in the nucleotide excision repair pathway are upregulated. Nevertheless, apoptotic mechanisms seem to be activated probably due to severe high-dose-induced complex DNA damage. The significant upregulation of CDKN1A, as a downstream gene of TP53, further validates programmed cell death. Finally, down-regulation of TIMELESS, signifies a correlation between IR response and circadian rhythm. Nonetheless, high-dose IR exposure effects regarding normal tissue (radiation toxicity) and its possible long-term outcomes should be studied to a greater extend.