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Suzuki K, Imaoka T, Tomita M, Sasatani M, Doi K, Tanaka S, Kai M, Yamada Y, Kakinuma S. Molecular and cellular basis of the dose-rate-dependent adverse effects of radiation exposure in animal models. Part I: Mammary gland and digestive tract. JOURNAL OF RADIATION RESEARCH 2023; 64:210-227. [PMID: 36773323 PMCID: PMC10036108 DOI: 10.1093/jrr/rrad002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Revised: 10/04/2022] [Indexed: 06/18/2023]
Abstract
While epidemiological data are available for the dose and dose-rate effectiveness factor (DDREF) for human populations, animal models have contributed significantly to providing quantitative data with mechanistic insights. The aim of the current review is to compile both the in vitro experiments with reference to the dose-rate effects of DNA damage and repair, and the animal studies, specific to rodents, with reference to the dose-rate effects of cancer development. In particular, the review focuses especially on the results pertaining to underlying biological mechanisms and discusses their possible involvement in the process of radiation-induced carcinogenesis. Because the concept of adverse outcome pathway (AOP) together with the key events has been considered as a clue to estimate radiation risks at low doses and low dose-rates, the review scrutinized the dose-rate dependency of the key events related to carcinogenesis, which enables us to unify the underlying critical mechanisms to establish a connection between animal experimental studies with human epidemiological studies.
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Affiliation(s)
- Keiji Suzuki
- Corresponding author. Department of Radiation Medical Sciences, Nagasaki University Atomic Bomb Disease Institute. 1-12-4 Sakamoto, Nagasaki 852-8523, Japan. Tel: +81-95-819-7116; Fax: +81-95-819-7117;
| | | | | | | | - Kazutaka Doi
- Department of Radiation Regulatory Science Research, National Institute of Radiological Sciences (NIRS), National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Satoshi Tanaka
- Department of Radiobiology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho-mura, Kamikita-gun, Aomori 039-3212, Japan
| | - Michiaki Kai
- Nippon Bunri University, 1727-162 Ichiki, Oita, Oita 870-0397, Japan
| | - Yutaka Yamada
- Department of Radiation Effects Research, National Institute of Radiological Sciences (NIRS), National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Shizuko Kakinuma
- Department of Radiation Effects Research, National Institute of Radiological Sciences (NIRS), National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
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Kudo KI, Tsuyama N, Nagata K, Imaoka T, Iizuka D, Sugai-Takahashi M, Muramatsu M, Sakai A. ΔNp63α transcriptionally represses p53 target genes involved in the radiation-induced DNA damage response. Radiat Oncol 2022; 17:183. [DOI: 10.1186/s13014-022-02139-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 10/05/2022] [Indexed: 11/16/2022] Open
Abstract
Abstract
Background
The DNA damage response (DDR) is a mechanism that protects cells against radiation-induced oxidative DNA damage by causing cell cycle arrest and apoptosis. TP63 is a member of the tumour suppressor TP53 gene family, and ΔNp63α, a TP63 splicing variant, is constitutively expressed in the stem cell-containing basal layer of stratified epithelial tissues, including the mammary gland, where it plays a critical role in stemness and tissue development. ΔNp63α has been reported to transcriptionally inhibit the tumour suppression protein p53. This p53-repressive activity may cause genomic instability in epithelial stem cells exposed to radiation. In this study, we analysed the inhibitory effect of ΔNp63α on radiation-induced DDR.
Methods
To elucidate the role of the p53-repressive effect of ΔNp63α in radiation response, we performed a p63-siRNA knockdown experiment using human mammary epithelial cells (HMECs) expressing ΔNp63α and then performed ectopic and entopic expression experiments using human induced pluripotent stem cells (hiPSCs). After irradiation, the expression of DDR-related genes and proteins in ΔNp63α-expressing and control cells was analysed by RT–qPCR, Western blotting, and flow cytometry.
Results
The mRNA/protein expression levels of BAX and p21 were significantly increased in p63-siRNA-treated HMECs (sip63) after X-ray irradiation (4 Gy, 0.7 Gy/min) but not in scramble-siRNA treated HMECs (scr). Transcriptomic analysis showed decreased RNA expression of cell cycle-related genes and increased expression of programmed cell death-related genes in sip63 cells compared to scr cells. Furthermore, flow cytometric analysis revealed an increase in apoptotic cells and a decrease in 5-ethynyl-2´-deoxyuridine uptake in sip63 cells compared to scr cells. On the other hand, both the ectopic and entopic expression of ΔNp63α in apoptosis-sensitive hiPSCs reduced the expression levels of BAX after irradiation and significantly decreased the number of apoptotic cells induced by radiation.
Conclusion
Taken together, these results indicate that ΔNp63α represses p53-related radiation-induced DDR, thereby potentially causing genomic instability in epithelial stem cells.
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Imaoka T, Nishimura M, Daino K, Hosoki A, Kudo KI, Iizuka D, Nagata K, Takabatake M, Nishimura Y, Kokubo T, Morioka T, Doi K, Shimada Y, Kakinuma S. DOSE-RATE EFFECT OF RADIATION ON RAT MAMMARY CARCINOGENESIS AND AN EMERGING ROLE FOR STEM CELL BIOLOGY. RADIATION PROTECTION DOSIMETRY 2022; 198:1036-1046. [PMID: 36083756 DOI: 10.1093/rpd/ncac050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 03/03/2022] [Accepted: 03/20/2021] [Indexed: 06/15/2023]
Abstract
The uncertain cancer risk of protracted radiation exposure at low dose rates is an important issue in radiological protection. Tissue stem/progenitor cells are a supposed origin of cancer and may contribute to the dose-rate effect on carcinogenesis. The authors have shown that female rats subjected to continuous whole body γ irradiation as juveniles or young adults have a notably reduced incidence of mammary cancer as compared with those irradiated acutely. Experiments using the mammosphere formation assay suggested the presence of radioresistant progenitor cells. Cell sorting indicated that basal progenitor cells in rat mammary gland were more resistant than luminal progenitors to killing by acute radiation, especially at high doses. Thus, the evidence indicates a cell-type-dependent inactivation of mammary cells that manifests only at high acute doses, implying a link to the observed dose-rate effect on carcinogenesis.
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Affiliation(s)
- Tatsuhiko Imaoka
- Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Mayumi Nishimura
- Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Kazuhiro Daino
- Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Ayaka Hosoki
- Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Ken-Ichi Kudo
- Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
- Department of Radiation Life Sciences, School of Medicine, Fukushima Medical University, Fukushima 960-1247, Japan
| | - Daisuke Iizuka
- Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Kento Nagata
- Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Masaru Takabatake
- Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
- Department of Radiological Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Tokyo 116-8551, Japan
| | - Yukiko Nishimura
- Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Toshiaki Kokubo
- Laboratory Animal and Genome Sciences Section, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Takamitsu Morioka
- Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Kazutaka Doi
- Department of Radiation Regulatory Science Research, National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Yoshiya Shimada
- Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
- Institute for Environmental Sciences, Aomori 039-3212, Japan
| | - Shizuko Kakinuma
- Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
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Hosoki A, Ogawa M, Nishimura Y, Nishimura M, Daino K, Kakinuma S, Shimada Y, Imaoka T. The effect of radiation on the ability of rat mammary cells to form mammospheres. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2020; 59:711-721. [PMID: 32996008 DOI: 10.1007/s00411-020-00869-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 08/29/2020] [Indexed: 06/11/2023]
Abstract
As classical transplantation repopulation assays for studying the radiobiology of rat mammary stem/progenitor cells are extremely time-consuming, this study aimed to characterize the radiobiological properties of mammospheres, spherical clumps of mammary cells formed under non-adherent culture conditions, which are a simple and widely used technique for assessing progenitor cell activity. Rat mammary cells were dissociated and used in transplantation repopulation assays and for the formation of mammospheres. Immunofluorescence for cytokeratin 14 and 18 was used to identify basal and luminal mammary epithelial cells, respectively. Incorporation of 5-bromo-2'-deoxyuridine was used to evaluate cell proliferation. The repopulating activity of the transplanted primary rat mammary cells demonstrated their radiosensitivity, reproducing previous data, with a significant reduction in repopulating activity at ≥ 2 Gy. Cells constituting rat mammospheres were positive for either cytokeratin 14 or 18, with occasional double-positive cells. Both proliferation and aggregation contributed to sphere formation. Cells obtained from the spheres showed lower repopulating activity after transplantation than primary cells. When primary cells were irradiated and then used for sphere formation, the efficiency of sphere formation was significantly decreased at 8 Gy but not at ≤ 6 Gy, indicating radioresistance of the formation process. Irradiation at 8 Gy reduced the proliferation of cells during sphere formation, whereas the cellular composition of the resulting spheres was unaffectes. Thus, mammosphere formation assays may measure a property of putative mammary progenitors that is different from what is measured in the classic transplantation repopulation assay in radiobiology.
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Affiliation(s)
- Ayaka Hosoki
- Fukushima Project Headquarters, National Institute of Radiological Sciences (NIRS), Chiba, Japan
- Healios KK Kobe Research Institute, Kobe, Japan
| | - Mari Ogawa
- Department of Radiation Effects Research, NIRS, National Institutes for Quantum and Radiological Science and Technology (QST), 4-9-1, Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Yukiko Nishimura
- Department of Radiation Effects Research, NIRS, National Institutes for Quantum and Radiological Science and Technology (QST), 4-9-1, Anagawa, Inage-ku, Chiba, 263-8555, Japan
- Institute for Environmental Sciences, Aomori, Japan
| | - Mayumi Nishimura
- Department of Radiation Effects Research, NIRS, National Institutes for Quantum and Radiological Science and Technology (QST), 4-9-1, Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Kazuhiro Daino
- Department of Radiation Effects Research, NIRS, National Institutes for Quantum and Radiological Science and Technology (QST), 4-9-1, Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Shizuko Kakinuma
- Department of Radiation Effects Research, NIRS, National Institutes for Quantum and Radiological Science and Technology (QST), 4-9-1, Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Yoshiya Shimada
- Executive Board, QST, Chiba, Japan
- Institute for Environmental Sciences, Aomori, Japan
| | - Tatsuhiko Imaoka
- Department of Radiation Effects Research, NIRS, National Institutes for Quantum and Radiological Science and Technology (QST), 4-9-1, Anagawa, Inage-ku, Chiba, 263-8555, Japan.
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