尽管放射治疗技术取得了进步，但肿瘤边缘和扩散浸润的癌细胞仍能接受亚细胞毒性剂量的光子。即使只涉及少数癌细胞，考虑到线粒体 DNA (mtDNA) 是辐射的主要目标并且 mtDNA 的损伤可能持续存在，表型后果也可能很重要。反过来，与线粒体活性氧（mtROS）产生增强相关的线粒体功能障碍可能会促进癌细胞迁移出照射场，自然地试图逃避治疗。在这项研究中，使用 MCF7 和 MDA-MB-231 人乳腺癌细胞作为模型，我们旨在阐明支持线粒体对亚临床剂量辐射 (< 2 Gy) 诱导的癌细胞迁移的分子机制。测试了线粒体功能障碍使用 mtDNA 多重 PCR、血氧测定法和 ROS 敏感荧光报告基因。照射后 48 小时，在存在或不存在针对特定 ROS 或下游效应子的抑制剂的情况下，在 Transwell 中测试迁移。在测试的抑制剂中，我们设计了一种靶向线粒体的人过氧化氢酶 (mtCAT)，以选择性地灭活线粒体 H2O2。亚临床剂量的光子照射（MCF7 为 0.5 Gy，MDA-MB-231 细胞为 0.125 Gy）依次影响 mtDNA 水平和/或完整性，增加 mtROS 产生，增加 MAP2K1/MEK1 基因表达，激活 ROS 敏感转录因子 NF-κB 和 AP1，并刺激乳腺癌细胞迁移。通过 MitoQ 进行药理学靶向 mtROS 或通过 mtCAT 表达进行基因靶向，可减轻亚临床剂量的照射引起的迁移。亚临床剂量的光子照射会促进人类乳腺癌迁移，这可以通过选择性靶向 mtROS 来抵消。© 2024。作者。

Despite technological advances in radiotherapy, cancer cells at the tumor margin and in diffusive infiltrates can receive subcytotoxic doses of photons. Even if only a minority of cancer cells are concerned, phenotypic consequences could be important considering that mitochondrial DNA (mtDNA) is a primary target of radiation and that damage to mtDNA can persist. In turn, mitochondrial dysfunction associated with enhanced mitochondrial ROS (mtROS) production could promote cancer cell migration out of the irradiation field in a natural attempt to escape therapy. In this study, using MCF7 and MDA-MB-231 human breast cancer cells as models, we aimed to elucidate the molecular mechanisms supporting a mitochondrial contribution to cancer cell migration induced by subclinical doses of irradiation (< 2 Gy).Mitochondrial dysfunction was tested using mtDNA multiplex PCR, oximetry, and ROS-sensitive fluorescent reporters. Migration was tested in transwells 48 h after irradiation in the presence or absence of inhibitors targeting specific ROS or downstream effectors. Among tested inhibitors, we designed a mitochondria-targeted version of human catalase (mtCAT) to selectively inactivate mitochondrial H2O2.Photon irradiation at subclinical doses (0.5 Gy for MCF7 and 0.125 Gy for MDA-MB-231 cells) sequentially affected mtDNA levels and/or integrity, increased mtROS production, increased MAP2K1/MEK1 gene expression, activated ROS-sensitive transcription factors NF-κB and AP1 and stimulated breast cancer cell migration. Targeting mtROS pharmacologically by MitoQ or genetically by mtCAT expression mitigated migration induced by a subclinical dose of irradiation.Subclinical doses of photon irradiation promote human breast cancer migration, which can be countered by selectively targeting mtROS.© 2024. The Author(s).