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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The purpose of this study is to investigate the radiobiological effect of heavy ion beames on intratumoral radioresistant and radiosensitive human tumor cells. Tumors of human origin, an ependymoblastoma (EB) with wild-type (wt) p53, a primitive neuroectodermal tumor (PNET) with wt p53, and a glioblastoma (GB) with mutant-type (mt) p53, were transplanted to nude mice, and the mice were irradiated with carbon
ion beams (290MeV/u) or 200kV X-rays. Tumors were excised 4, 6, or 24 hours after 2Gy
irradiation. A part of each tumor was fixed in formalin and embedded in paraffin. Thin sections were stained with H.E., GFAP or TUNEL for microscopic study. The other part of each tumor was stored in RNA stabilization solution, and total RNA was extracted for cDNA microarray analysis. Furthermore, some other part of the EB was frozen immediately and two types of tissue sample (A: tumor cells around vessels and B: tumor cells in the other area) were obtained using laser capture microdissection, and their RNA was extracted for cDNA microarray analysis. In wt-p53 tumors, apoptosis increased 6 hours after irradiation, and then GFAP-positive rate increased. The tumors with wt-p53 showed significant changes in gene expression following irradiation. Pathway analysis of up- and down-regulated genes demonstrated that apoptosis, p53 signaling pathway, and cell cycle are involved significantly. There was little difference between the gene expression profiles induced by carbon ion beams and those by X-rays. But, the two types of tumor cells in the EB showed different gene expression profiles following irradiation. In contrast, the tumor with mt-p53 showed much less change in gene expression after 2Gy irradiation. However, the tumor showed significant change following 8Gy or 16Gy irradiation, and the gene expression profiles induced by carbon ion beams and those by X-rays were different.
腫瘍内の放射線抵抗性細胞に対する重粒子線の効果と検討
