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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Tumor-treating fields (TTFs) - a type of electromagnetic field-based therapy using low-intensity electrical fields - has recently been characterized as a potential anticancer therapy for glioblastoma multiforme (GBM). However, the molecular mechanisms involved remain poorly understood. Our results show that the activation of autophagy contributes to the TTF-induced anti-GBM activity in vitro or in vivo and GBM patient stem cells or primary in vivo culture systems. TTF-treatment upregulated several autophagy-related genes (~2-fold) and induced cytomorphological changes. TTF-induced autophagy in GBM was associated with decreased Akt2 expression, not Akt1 or Akt3, via the mTOR/p70S6K pathway. An Affymetrix GeneChip miRNA 4.0 Array analysis revealed that TTFs altered the expression of many microRNAs (miRNAs). TTF-induced autophagy upregulated miR-29b, which subsequently suppressed the Akt signaling pathway. A luciferase reporter assay confirmed that TTFs induced miR-29b to target Akt2, negatively affecting Akt2 expression thereby triggering autophagy. TTF-induced autophagy suppressed tumor growth in GBM mouse models subjected to TTFs as determined by positron emission tomography and computed tomography (PET-CT). GBM patient stem cells and a primary in vivo culture system with high Akt2 levels also showed TTF-induced inhibition. Taken together, our results identified autophagy as a critical cell death pathway triggered by TTFs in GBM and indicate that TTF is a potential treatment option for GBM.
Tumor-treating fields induce autophagy by blocking the Akt2/miR29b axis in glioblastoma cells.
