Katsuki Shohei, Minami Kazumasa, Oniwa Karin, Yagi Masashi, Shimizu Shinichi, Hamatani Noriaki, Takashina Masaaki, Kanai Tatsuaki, Ogawa Kazuhiko
Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, 1-7 Yamadaoka, Suita, Osaka, 565-0871, Japan.
Department of Carbon Ion Radiotherapy, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
J Radiat Res. 2025 Jan 22;66(1):97-102. doi: 10.1093/jrr/rrae091.
Recently, ultra-high dose rate (> 40 Gy/s, uHDR; FLASH) radiation therapy (RT) has attracted interest, because the FLASH effect that is, while a cell-killing effect on cancer cells remains, the damage to normal tissue could be spared has been reported. This study aimed to compare the immune-related protein expression on cancer cells after γ-ray, conventionally used dose rate (Conv) carbon ion (C-ion), and uHDR C-ion. B16F10 murine melanoma and Pan02 murine pancreas cancer were irradiated with γ-ray at Osaka University and with C-ion at Osaka HIMAK. The dose rates at 1.16 Gy/s for Conv and 380 Gy/s for uHDR irradiation. The expressed calreticulin (CRT), major histocompatibility complex class (MHC)-I, and programmed cell death 1 ligand (PD-L1) were evaluated by flow cytometry. Western blotting and PCR were utilized to evaluate endoplasmic reticulum (ER) stress, DNA damage, and its repair pathway. CRT, MHC-I on B16F10 was also increased by irradiation, while only C-ion increased MHC-I on Pan02. Notably, PD-L1 on B16F10 was increased after irradiation with both γ-ray and C-ion, while uHDR C-ion suppressed the expression of PD-L1 on Pan02. The present study indicated that uHDR C-ion has a different impact on the repair pathway of DNA damage and ER than the Conv C-ion. This is the first study to show the immune-related protein expressions on cancer cells after uHDR C-ion irradiation.
最近，超高剂量率（>40 Gy/s，uHDR；FLASH）放射治疗（RT）引起了人们的关注，因为有报道称存在FLASH效应，即虽然对癌细胞的杀伤作用仍然存在，但对正常组织的损伤可以避免。本研究旨在比较γ射线、传统剂量率（Conv）碳离子（C离子）和uHDR C离子照射后癌细胞上免疫相关蛋白的表达。B16F10小鼠黑色素瘤和Pan02小鼠胰腺癌在大阪大学接受γ射线照射，在大阪HIMAK接受C离子照射。Conv照射的剂量率为1.16 Gy/s，uHDR照射的剂量率为380 Gy/s。通过流式细胞术评估钙网蛋白（CRT）、主要组织相容性复合体I类（MHC-I）和程序性细胞死亡1配体（PD-L1）的表达。利用蛋白质免疫印迹法和聚合酶链反应评估内质网（ER）应激、DNA损伤及其修复途径。照射后B16F10上的CRT、MHC-I也增加，而只有C离子增加了Pan02上的MHC-I。值得注意的是，γ射线和C离子照射后B16F10上的PD-L1增加，而uHDR C离子抑制了Pan02上PD-L1的表达。本研究表明，uHDR C离子与Conv C离子相比，对DNA损伤和ER的修复途径有不同的影响。这是第一项展示uHDR C离子照射后癌细胞上免疫相关蛋白表达的研究。
