Tanzhu Guilong, Peng Haiqin, Chen Liu, Xiao Gang, Ning Jiaoyang, Chen Ling, Zhou Rongrong
Department of Oncology, Xiangya Hospital, Central South University, Changsha, 410008, China.
Department of Neurosurgery, Chinese People's Liberation Army of China (PLA) General Hospital, Medical School of Chinese PLA, Institute of Neurosurgery of Chinese PLA, 100853, Beijing, China.
Brain Stimul. 2025 Jul 27;18(5):1426-1440. doi: 10.1016/j.brs.2025.07.014.
Brain metastasis (BrM) is a common complication of advanced tumors with poor prognosis. Although radiotherapy remains a key treatment for BrM, it is plagued by issues such as radiation-induced brain necrosis, neurocognitive impairment, and progress post-treatment. Tumor Treating Fields (TTFields) therapy employs medium frequency (100∼300 kHz) and low intensity (1∼3 v/cm) alternating electric fields to inhibit tumors. We explored the effects and mechanisms of TTFields combined with ionizing radiation (IR) on the malignant phenotype of lung cancer brain metastasis (LCBM) cells, with the aim of advancing the clinical adoption of TTFields.
LCBM cells H1915, PC9-Brm and primary cells were used. The experiments included four groups: Control, 6 Gy, TTFields, and 6 Gy + TTFields group. Cell viability and the number of EDU or Ki67-positive cells, ability of migration and colony formation were assessed; Cell morphology was observed by H&E staining; Bulk transcriptome revealed the potential mechanisms, with the protein levels of differentially expressed genes (DEGs) verified through immunofluorescence assay. DNA damage repair pathways were validated by Western Blot. Additionally, ROS levels, and HO-1 expression were evaluated.
The combination of 150 kHz, 2∼2.5 v/cm TTFields and 6 Gy IR effectively suppressed the viability and the number of EDU-positive and Ki67-positive LCBM cells. Following TTFields and IR, the tumor cells exhibited altered morphology and reduced clonogenic and migratory capacities. RNA-seq revealed associations between TTFields combined with IR and various biological processes and mechanisms, including redox reactions (primarily related to mitochondria), DNA replication, transition metal ion transmembrane transport, and heme metabolism. Furthermore, TTFields combined with IR enhanced γH2AX and 53BP1 levels. Increased ROS and HO-1 expression were observed post-treatment. Similarly, LCBM primary cells exhibited decreased Ki67-positive cells along with increased γH2AX and 53BP1 foci following TTFields and IR. TTFields combined with IR exhibited significant suppression on homologous recombination (HR) markers (p-ATM, RAD51), non-homologous end joining (NHEJ) components (DNA-PKcs, KU70, KU80), and microhomology-mediated end joining (MMEJ) effectors (PARP1, p95-NBS1) versus RT alone.
TTFields combined with IR effectively inhibits LCBM cells. Mechanistically, this combined treatment enhanced DNA damage, suppressed DNA damage repair, and elevates ROS levels.
脑转移（BrM）是晚期肿瘤常见的并发症，预后较差。尽管放射治疗仍然是BrM的关键治疗方法，但它受到诸如放射性脑坏死、神经认知障碍和治疗后进展等问题的困扰。肿瘤电场疗法（TTFields）采用中频（100∼300kHz）和低强度（1∼3v/cm）的交变电场来抑制肿瘤。我们探讨了TTFields联合电离辐射（IR）对肺癌脑转移（LCBM）细胞恶性表型的影响及其机制，旨在推动TTFields在临床上的应用。
使用LCBM细胞H1915、PC9-Brm和原代细胞。实验分为四组：对照组、6Gy组、TTFields组和6Gy + TTFields组。评估细胞活力、EDU或Ki67阳性细胞数量、迁移能力和集落形成能力；通过苏木精-伊红（H&E）染色观察细胞形态；全转录组揭示潜在机制，并通过免疫荧光测定验证差异表达基因（DEGs）的蛋白质水平。通过蛋白质印迹法验证DNA损伤修复途径。此外，评估活性氧（ROS）水平和血红素加氧酶-1（HO-1）表达。
150kHz、2∼2.5v/cm的TTFields与6Gy IR联合使用可有效抑制LCBM细胞的活力以及EDU阳性和Ki67阳性细胞的数量。在TTFields和IR处理后，肿瘤细胞形态发生改变，克隆形成和迁移能力降低。RNA测序揭示了TTFields联合IR与各种生物学过程和机制之间的关联，包括氧化还原反应（主要与线粒体相关）、DNA复制、过渡金属离子跨膜转运和血红素代谢。此外，TTFields联合IR可提高γH2AX和53BP1水平。处理后观察到ROS和HO-1表达增加。同样，在TTFields和IR处理后，LCBM原代细胞中Ki67阳性细胞减少，γH2AX和53BP1焦点增加。与单独放疗相比，TTFields联合IR对同源重组（HR）标志物（p-ATM、RAD51）、非同源末端连接（NHEJ）成分（DNA-PKcs、KU70、KU80）和微同源性介导的末端连接（MMEJ）效应器（PARP1、p95-NBS1）具有显著抑制作用。
TTFields联合IR可有效抑制LCBM细胞。从机制上讲，这种联合治疗增强了DNA损伤，抑制了DNA损伤修复，并提高了ROS水平。
