Rodrigues Amon Rosana Lopes, Almeida Beatriz, Nogueira-Pedro Amanda, Naoto Makiyama Edson, Fock Ricardo Ambrósio
Department of Clinical and Toxicological Analysis, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil.
Department of Clinical and Toxicological Analysis, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil.
Arch Biochem Biophys. 2025 Oct;772:110563. doi: 10.1016/j.abb.2025.110563. Epub 2025 Jul 22.
Mesenchymal stem cells (MSCs) in the bone marrow (BM) stroma modulate hematopoiesis through paracrine signaling. In leukemia, the BM stroma can be reprogrammed, affecting normal hematopoiesis. Radiation therapy, a common treatment for hematological malignancies, impacts not only directly irradiated cells but also nearby non-irradiated cells through the radiation-induced bystander effect (RIBE). This phenomenon occurs when non-irradiated cells exhibit radiation damage due to signals from nearby irradiated cells, which undergo changes through communication with irradiated neighbors, primarily via paracrine signaling. This challenges the traditional view that radiation damage is confined to directly irradiated cells. However, how this phenomenon modulates MSCs and its specific effects on leukemic cells remain unclear. MSCs were irradiated with doses of 4, 6, and 15Gy, and their secretome was analyzed to understand how these factors influence leukemia cells. The results showed that doses higher than 6Gy significantly affected MSC viability, apoptosis, and cell cycle distribution, with 6Gy chosen for further RIBE analysis due to its balance between cellular damage and viability. Clonogenic assays revealed that leukemic cells cultured with 6Gy-conditioned media showed reduced colony formation and metabolic activity. Although cell viability was unaffected, RIBE altered the cell cycle in G-CSF-stimulated leukemic cells, decreasing Ccnd1 expression and increasing Cdkn1a expression. Gata3 expression was also reduced. Flow cytometry revealed insignificant changes in surface markers, except for CD3e in G-CSF-stimulated cells. These findings provide new insights into how radiation-induced bystander effects alter the behavior of leukemic cells, prompting further research into RIBE's implications for cancer therapy.
骨髓（BM）基质中的间充质干细胞（MSC）通过旁分泌信号调节造血作用。在白血病中，BM基质可被重新编程，影响正常造血。放射治疗是血液系统恶性肿瘤的常见治疗方法，它不仅会直接影响受照射细胞，还会通过辐射诱导的旁观者效应（RIBE）影响附近的未受照射细胞。当未受照射的细胞由于来自附近受照射细胞的信号而表现出辐射损伤时，就会发生这种现象，这些受照射细胞通过与受照射的邻近细胞通讯（主要通过旁分泌信号）而发生变化。这对辐射损伤仅限于直接受照射细胞的传统观点提出了挑战。然而，这种现象如何调节MSC及其对白血病细胞的具体影响仍不清楚。用4、6和15Gy的剂量照射MSC，并分析其分泌组，以了解这些因素如何影响白血病细胞。结果表明，高于6Gy的剂量显著影响MSC的活力、凋亡和细胞周期分布，由于其在细胞损伤和活力之间的平衡，选择6Gy进行进一步的RIBE分析。克隆形成试验表明，用6Gy条件培养基培养的白血病细胞集落形成和代谢活性降低。虽然细胞活力未受影响，但RIBE改变了G-CSF刺激的白血病细胞的细胞周期，降低了Ccnd1表达并增加了Cdkn1a表达。Gata3表达也降低。流式细胞术显示表面标志物无明显变化，G-CSF刺激的细胞中的CD3e除外。这些发现为辐射诱导的旁观者效应如何改变白血病细胞的行为提供了新的见解，促使人们进一步研究RIBE对癌症治疗的影响。
