Presentation Studies on defensive cellular response induced by cytoplasm/nucleus targeted irradiation using SPICE-NIRS microbeam

Konishi, Teruaki  ,  Wang, Jun  ,  Kobayashi, Alisa  ,  Autsavapromporn, Narongchai  ,  Ahbrizal Farizal Tengku Ahmad, Tengku  ,  Ohsawa, Daisuke  ,  Furusawa, Yoshiya

Direct hits to the nucleus by radiation are known as the primary cause of various radio-biological effects. However, the cells will have equal chances of being exposed at the cytoplasm, and results in damages that may activate various signaling pathways that mediates defensive response. We examined the velocity of DNA double-strand break (DSB) repair in microbeam irradiated WI-38 human normal fibroblast cells that were targeted in the nucleus, cytoplasm, or both nucleus/cytoplasm using SPICE-NIRS microbeam. Cells were fixed at various time points between 1hr to 24hr post irradiation to quantify the residual of γ-H2AX/nucleus obtained from microscopic images. Nucleus targeted irradiation significantly induced γ-H2AX, which were proportional to the number of protons per nucleus. Cells irradiated with 500 protons per nucleus showed less residual of γ-H2AX in the cells with additional of 200 protons in the cytoplasm at 8hr and 16hr post-irradiation. Contrary, the cytoplasm irradiation alone shows higher γ-H2AX level at 4 hr post-irradiation, but decreased to level equivalent to the controls. Taken together, non-DNA damage induced directly by radiation may have activated DSB repair pathways as a defensive cellular response against radiation damages.
1st QST International Symposium Quantum Life Science

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