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 and Radiological Science and Technology.
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Introduction
64Cu-diacetyl-bis (N4-methylthiosemicarbazone) (64Cu-ATSM) is an imaging agent for positron emission tomography (PET) that targets hypoxic tumors. 64Cu-ATSM is also reported to be a potential agent for internal radiotherapy. In a mouse colon carcinoma (Colon-26) model, we have shown that 64Cu-ATSM preferentially localizes in intratumoral regions with a high density of CD133+ cells, which show characteristics of cancer stem cells or cancer stem cell-like cells (collectively referred here as CSCs). In this study, we evaluated the therapeutic effect of 64Cu-ATSM in relation to CD133 expression using this model.
\nMethods
Systemic administration of 37 MBq 64Cu-ATSM or saline was conducted twice within a 1-week interval to mice bearing 1-week-old Colon-26 tumors (days 0–7). At day 19, tumor size measurement, flow cytometry analysis and experimental lung metastatic assay were performed. The therapeutic effect of 64Cu-ATSM on sorted CD133+ and CD133− Colon-26 cells was also examined in vitro.
\nResults
In vivo studies showed that 64Cu-ATSM treatment inhibited tumor growth. The percentage of CD133+ cells and metastatic ability in 64Cu-ATSM treated tumors was decreased compared with that in control animals. In vitro studies demonstrated that 64Cu-ATSM accumulated in cells under hypoxic conditions and incorporation of 64Cu-ATSM under hypoxia caused cell death in both CD133+ and CD133− cells in a similar extent.
\nConclusions
64Cu-ATSM administration reduced tumor volume as well as the percentage of CD133+ cells and the metastatic ability of Colon-26 tumors. Together with our data, it is suggested that 64Cu-ATSM accumulates in regions high in CD133+ highly tumorigenic cells and kills such regions by radiation, resulting in a decrease of the percentage of CD133+ cells.
Internal radiotherapy with copper-64-diacetyl-bis (N4-methylthiosemicarbazone) reduces CD133+ highly tumorigenic cells and metastatic ability of mouse colon carcinoma
