Living in Space
Integral Understanding of life-regulation mechanism from "SPACE"

Estimation of carcinogenic risk after exposure to space radiation by pathological and genomic analyses – Publicly Invited Research 2018－2019

1. A01 Ogura
2. A01 H. Takahashi
3. A01 S. Takahashi
4. A01 Michiue
5. A01 Hinoi
6. A01 Tsumoto
7. A01 Nikawa
8. A01 Chatani
9. A01 Kawakami
10. A01 Akiyama
11. A01 Tomita

1. A02 Shinohara
2. A02 Mieda
3. A02 Maekawa
4. A02 Abe
5. A02 Ohgami
6. A02 Kawano
7. A02 Takano

1. A03 Suzuki
2. A03 Nakamura
3. A03 Harada
4. A03 Kobayashi
5. A03 Miyamoto
6. A03 Funayama
7. A03 Kakinuma

1. B01 Lazarus
2. B01 Kato
3. B01 Kunieda
4. B01 Kitaya
5. B01 Sawano

Research Subject	Estimation of carcinogenic risk after exposure to space radiation by pathological and genomic analyses
Research Group Leader	Shizuko Kakinuma Deputy Director General, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology Website https://www.qst.go.jp/site/nirs-english/1366.html
Research Collaborator(s)	Takamitsu Morioka Principal Researcher, Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology Kazuhiro Daino Principal Researcher, Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology Chizuru Tsuruoka Researcher, Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology Yi Shang Researcher, Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology Yoshiko Amasaki Researcher, Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology Kenshi Suzuki Postdoctoral Fellow, Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology

Unlike on the Earth’s surface, in space we are exposed to a different spectrum of radiation including cosmic radiation. Cosmic radiation includes high energy heavy particles such as iron ions, as well as protons and neutrons, with the potential for high biological effectiveness. Although the biological effects of radiation and the relation between dose and carcinogenic risk can be understood from epidemiological data, such as that on atomic bomb survivors, there is insufficient data on carcinogenic risk from the mixed radiation field at low doses / low dose rates relevant to the space environment. Although the fluence of heavy particles in space is low, the dense and complex DNA lesions that can be formed from the passage of such ions as iron or silicon through the cells make the repair of cells more difficult, and may have greater biological effectiveness and thus greater cancer risk than for low LET radiation.

In this study, we will analyze tumor samples obtained from lifespan experiments in B6C3F1 mice after irradiation with iron, silicon or argon ions. First, we will perform pathology analysis of tumors induced after heavy ion exposure from a variety of organs, and then analyze genomic mutations in the tumors. We aim to compare the pathology and genomic data to similar data from previous low LET radiation studies, in order to understand the differences in carcinogenic mechanisms and risk due to high energy heavy ion exposure, which would be experienced in the space radiation environment.