Theranostics 2019; 9(6):1538-1549. doi:10.7150/thno.30353

Research Paper

Anti-tumor effects and potential therapeutic response biomarkers in α-emitting meta-211At-astato-benzylguanidine therapy for malignant pheochromocytoma explored by RNA-sequencing

Yasuhiro Ohshima1*, Nobuaki Kono2*, Yuichiro Yokota1*, Shigeki Watanabe1, Ichiro Sasaki1, Noriko S. Ishioka1, Tetsuya Sakashita1✉, Kazuharu Arakawa2,3✉

1. Department of Radiation-Applied Biology Research, Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan.
2. Institute for Advanced Biosciences, Keio University, 246-2 Mizukami, Kakuganji, Tsuruoka, Yamagata, 997-0052, Japan
3. Faculty of Environment and Information Studies, Keio University, 5322 Endo, Fujisawa, Kanagawa, 252-0882, Japan
*Co-first authors

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Citation:
Ohshima Y, Kono N, Yokota Y, Watanabe S, Sasaki I, Ishioka NS, Sakashita T, Arakawa K. Anti-tumor effects and potential therapeutic response biomarkers in α-emitting meta-211At-astato-benzylguanidine therapy for malignant pheochromocytoma explored by RNA-sequencing. Theranostics 2019; 9(6):1538-1549. doi:10.7150/thno.30353. Available from http://www.thno.org/v09p1538.htm

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Abstract

Targeted α-particle therapy is a promising option for patients with malignant pheochromocytoma. Recent observations regarding meta-211At-astato-benzylguanidine (211At-MABG) in a pheochromocytoma mouse model showed a strong anti-tumor effect, though the molecular mechanism remains elusive. Here, we present the first comprehensive RNA-sequencing (RNA-seq) data for pheochromocytoma cells based on in vitro 211At-MABG administration experiments. Key genes and pathways in the tumor α-particle radiation response are also examined to obtain potential response biomarkers.

Methods: We evaluated genome-wide transcriptional alterations in the rat pheochromocytoma cell line PC12 at 3, 6, and 12 h after 211At-MABG treatment; a control experiment using 60Co γ-ray irradiation was carried out to highlight 211At-MABG-specific gene expression. For comparisons, 10% and 80% iso-survival doses (0.8 and 0.1 kBq/mL for 211At-MABG and 10 and 1 Gy for 60Co γ-rays) were used.

Results: Enrichment analysis of differentially expressed genes (DEGs) and analysis of the gene expression profiles of cell cycle checkpoints revealed similar modes of cell death via the p53-p21 signaling pathway after 211At-MABG treatment and γ-ray irradiation. The top list of ranked DEGs demonstrated the expression of key genes on the decrease in the survival following 211At-MABG exposure, and four potential genes (Mien1, Otub1, Vdac1 and Vegfa genes) of 211At-MABG therapy. Western blot analysis indicated increased expression of TSPO in 211At-MABG-treated cells, suggesting its potential as a PET imaging probe.

Conclusion: Comprehensive RNA-seq revealed contrasting cellular responses to γ-ray and α-particle therapy, leading to the identification of four potential candidate genes that may serve as molecular imaging and 211At-MABG therapy targets.

Keywords: α-particle, meta-211At-astato-benzylguanidine, RNA-sequencing, pheochromocytoma, PET imaging, radionuclide therapy