量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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Carbon-ion (C-ion) radiotherapy (RT) is an advanced effective RT in tumors that are difficult to be cured by conventional RT due to its biological properties and excellent dose distribution. Although C-ion radiotherapy has shown good outcomes, metastasis control is an important matter as with any type of cancer treatment. There are some reports that C-ion irradiation tends to suppress metastasis or relevant abilities at in vitro and in vivo models. However, the underlying mechanisms are still not clearly understood.
To improve C-ion RT, we aimed to find an optimal combination therapy for C-ion radiotherapy to prevent distant metastasis. In this study, we evaluated dendritic cells (DCs) immunotherapy, as a partner for C-ion radiotherapy. We used mouse allograft models using four mouse cancer cell lines (NR-S1, LM8, LLC and Colon26) and three mouse strains (C3H/He, C57BL/6J and BALB/c) under conditions that there were no significant effects on growth of transplanted tumor by the C-ion treatments. In NR-S1 or LM8 grafted C3H/He and LLC grafted C57BL/6J models, the number of lung metastasis was significantly decreased by the combined therapy. However, Colon26 grafted BALB/c model did not show the enhancement of metastasis inhibition by the combination treatment. To clarify the mechanisms behind the model difference, we investigated further by comparing LLC grafted C57BL/6J and Colon26 grafted BALB/c models. Dual legs grafted-one leg C-ion irradiation assay clearly demonstrated that local C-ion treatment was able to repress lung metastasis from distal non-irradiated tumor in both models. In contrast, in vitro co-culture assay indicated that C-ion irradiated Colon26 cells were not able to activate iDCs into the mature DCs, whereas LLC cells could. These results indicate that C-ion local irradiation by itself has strong ability to activate metastasis inhibition in the whole body, and genetic background or/and cancer cell type may have potent impact on the efficiency of the combination therapy.
会議概要（会議名, 開催地, 会期, 主催者等）
15th International Congress of Radiation Research (ICRR 2015)
Analysis of Underlying Mechanisms for Combination Therapy of Carbon-ion Irradiation and Dendritic Cell Immunotherapy
