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Department of Radiobiology/Molecular Epidemiology

Department of Radiobiology/Molecular Epidemiology
There is numerous epidemiological data on the effects of radiation exposure on disease incidence and death in humans. However, the biological mechanisms underlying the observed effects of atomic-bomb radiation on the development of human diseases, especially cancer, are unknown.The Department of Radiobiology/Molecular Epidemiology uses molecular oncological and immunological approaches with epidemiological study design, to investigate radiation effects on health and to clarify the etiology of diseases among atomic-bomb survivors and their children, in terms of host-environment interaction.
Molecular Oncology Studies: Most researchers believe the process of cancer development involves multiple steps. For a normal cell to become malignant, mutations and alterations of selected genes must accumulate in the cell, often resulting in disfunction of regulatory systems responsible for the tightly controlled cell growth and death. Ionizing radiation is known to damage DNA, e.g., gene mutations and epigenetic changes. Presumably, atomic-bomb radiation damaged some of the important genes involved in cancer development.

Our molecular oncology studies explore the molecular biological mechanisms behind radiation carcinogenesis by identifying the damaged genes and gene systems that have been altered in the post-bombing population. Our researchers use state-of-the-art molecular biological techniques to analyze survivors' tissue samples.

Immunology Studies: The immune system protects the body from the intrusion of alien substances, such as bacteria and parasites, and in some cases from the continued proliferation of malignant cells or even from constantly-generating malignant cells (immunosurveillance against cancer). Host immunological response, specifically inflammatory response, is thought to be a key mechanism in development of various lifestyle-associated diseases such as diabetes, coronary heart disease, and several cancers. Through repeated division, a pool of blood stem cells produces cells that, in turn, differentiate into the functionally and phenotypically heterogeneous cell subpopulations that make up the immune system. These subpopulations closely interact with and regulate one another to effectively eliminate intruding substances.

Our immunology studies investigate radiation-induced immunological changes relating to disease development in A-bomb survivors. In addition, we have studied somatic mutations in blood cells using immunological methods.

Immunogenome Studies: The human genome, the complete set of genetic information in people's DNA, differs among individuals, and this is in part responsible for individual differences in biological predispositions such as susceptibility to environmental chemicals, radiation exposure, and development of lifestyle-associated diseases. Our Immunogenome Study investigates genetic polymorphisms responsible for inter-individual differences in susceptibility to radiation effects and also the development of lifestyle-associated diseases such as cancer and diabetes mellitus, aiming at personalized prevention of radiation-associated diseases.

Research Scientists and their Research Interests

Yoichiro Kusunoki, PhD, Department Chief
Radiation exposure and immunosenescence
Molecular epidemiology on immune-related diseases
Tomonori Hayashi, PhD, Assistant Department Chief
Immunosenescence in the radiation exposed
Genetic susceptibility to immune-related diseases
Homeostasis and intercellular communication
Kei Nakachi, PhD, RERF Consultant and Project Principal Scientist
Studies of immunosenescence and other late effects of acute ionizing radiation exposure in A-bomb survivors
Yoichiro Kusunoki, PhD
Masataka Taga, PhD
Molecular oncological study of solid cancer (lung and colorectal cancers) among A-bomb survivors
Reiko Ito, PhD
Molecular pathological study on tumor specimens from A-bomb survivors
Yasuharu Niwa, PhD
Molecular biological analysis of lifestyle-associated diseases among A-bomb survivors
Kiyohiro Hamatani, PhD
Molecular oncology study of solid cancer (thyroid, colorectal and lung cancers) among A-bomb survivors
Tomonori Hayashi, PhD
Kengo Yoshida, PhD
Immunogenetic susceptibility to cancer and non-cancer diseases
Aging with special reference to immune functions
Junko Kajimura, PhD
Studies of immunosenescence and other late effects of acute ionizing radiation exposure in A-bomb survivors
Seishi Kyoizumi, PhD (Project Research Scientist)
Studies of immunosenescence and other late effects of acute ionizing radiation exposure in A-bomb survivors