Natural background ionizing radiation is present on the earth’s surface; however, the biological role of this chronic low-dose-rate exposure remains unknown. The Researching the Effects of the Presence and Absence of Ionizing Radiation (REPAIR) project is examining the impacts of sub-natural background radiation exposure through experiments conducted 2 km underground in SNOLAB. The rock overburden combined with experiment-specific shielding provides a background radiation dose rate 30 times lower than on the surface. We hypothesize that natural background radiation is essential for life and maintains genomic stability and that prolonged exposure to sub-background environments will be detrimental to biological systems. To evaluate this, human hybrid CGL1 cells were continuously cultured in SNOLAB and our surface control laboratory for 16 weeks. Cells were assayed every 4 weeks for growth rate, alkaline phosphatase (ALP) activity (a marker of cellular transformation in the CGL1 system), and the expression of genes related to DNA damage and cell cycle regulation. A subset of cells was also exposed to a challenge radiation dose (0.1 to 8 Gy of X rays) and assayed for clonogenic survival and DNA double-strand break induction to examine if prolonged sub-background exposure alters the cellular response to high-dose irradiation. At each 4-week time point, sub-background radiation exposure did not significantly alter cell growth rates, survival, DNA damage, or gene expression. However, cells cultured in SNOLAB showed significantly higher ALP activity, a marker of carcinogenesis in these cells, which increased with longer exposure to the sub-background environment, indicative of neoplastic progression. Overall, these data suggest that sub-background radiation exposure does not impact growth, survival, or DNA damage in CGL1 cells but may lead to increased rates of neoplastic transformation, highlighting a potentially important role for natural background radiation in maintaining normal cellular function and genomic stability.
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October 2024
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October 08 2024
The Role of Natural Background Radiation in Maintaining Genomic Stability in the CGL1 Human Hybrid Model System
Jake Pirkkanen;
aSchool of Natural Sciences, Laurentian University, Sudbury, Ontario, Canada
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Taylor Laframboise;
aSchool of Natural Sciences, Laurentian University, Sudbury, Ontario, Canada
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Jayden Peterson;
Jayden Peterson
aSchool of Natural Sciences, Laurentian University, Sudbury, Ontario, Canada
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Alyssa Labelle;
Alyssa Labelle
aSchool of Natural Sciences, Laurentian University, Sudbury, Ontario, Canada
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Forest Mahoney;
Forest Mahoney
aSchool of Natural Sciences, Laurentian University, Sudbury, Ontario, Canada
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Michel Lapointe;
Michel Lapointe
2
aSchool of Natural Sciences, Laurentian University, Sudbury, Ontario, Canada
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Marc S. Mendonca;
Marc S. Mendonca
bDepartment of Radiation Oncology, Radiation and Cancer Biology Laboratories, and Department of Medical & Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana
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T.C. Tai;
T.C. Tai
aSchool of Natural Sciences, Laurentian University, Sudbury, Ontario, Canada
cMedical Sciences Division, Northern Ontario School of Medicine University, Sudbury, Ontario, Canada
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Simon J. Lees;
Simon J. Lees
cMedical Sciences Division, Northern Ontario School of Medicine University, Sudbury, Ontario, Canada
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Sujeenthar Tharmalingam;
Sujeenthar Tharmalingam
aSchool of Natural Sciences, Laurentian University, Sudbury, Ontario, Canada
cMedical Sciences Division, Northern Ontario School of Medicine University, Sudbury, Ontario, Canada
dHealth Sciences North Research Institute, Sudbury, Ontario, Canada
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Douglas R. Boreham;
Douglas R. Boreham
aSchool of Natural Sciences, Laurentian University, Sudbury, Ontario, Canada
cMedical Sciences Division, Northern Ontario School of Medicine University, Sudbury, Ontario, Canada
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Christopher Thome
Christopher Thome
3
aSchool of Natural Sciences, Laurentian University, Sudbury, Ontario, Canada
cMedical Sciences Division, Northern Ontario School of Medicine University, Sudbury, Ontario, Canada
dHealth Sciences North Research Institute, Sudbury, Ontario, Canada
3Corresponding author: Christopher Thome, NOSM University, 935 Ramsey Lake Road, Sudbury, Ontario, Canada, P3E 2C6; email: [email protected].
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Radiat Res (2024) 202 (4): 617–625.
Article history
Received:
November 22 2023
Accepted:
June 26 2024
Citation
Jake Pirkkanen, Taylor Laframboise, Jayden Peterson, Alyssa Labelle, Forest Mahoney, Michel Lapointe, Marc S. Mendonca, T.C. Tai, Simon J. Lees, Sujeenthar Tharmalingam, Douglas R. Boreham, Christopher Thome; The Role of Natural Background Radiation in Maintaining Genomic Stability in the CGL1 Human Hybrid Model System. Radiat Res 1 October 2024; 202 (4): 617–625. doi: https://doi.org/10.1667/RADE-23-00243.1
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