Ionizing radiation-induced DNA damage and its cellular responses

This paper outlined 'ionizing radiation-induced DNA damage and cellular response against the damage' and introduced the results of applied research such as 'radiotherapy of cancer' and 'development of radiation damage protection agents'. Genetic diseases showing radiosensitivity and their causative genes have been discovered, and further identification of new causative genes is expected to proceed. This paper explains DNA repair mechanisms, radiation-induced cell death (apoptosis) and tissue damage, cell life/death selection control mechanism, and so forth. The cells damaged by apoptosis are eliminated for preventing mutagenesis induction due to DNA damage and thereby caused generation of the cells that express carcinogenesis. Stem cells such as ES cells and iPS cells have the ability to self-propagate while maintaining undifferentiated state and the ability to differentiate into functional cells. The high DNA repair ability of stem cells and the induction of differentiation through exposure are thought to be important mechanisms to prevent the development of cancer stem cells. Due to the progress of elucidation of the cell death induction mechanism of radiation-exposed cells at a biomolecular level, it became possible to develop radioprotective agents targeting in vivo proteins that are specific p53 inhibitors. By making cells absorb the protein, as a drug, to which cell membrane-permeable peptide sequence has been added, the cells can be controlled. (A.O.)