Tumour microenvironments are hallmarked in many cancer types. In haematological malignancies, bone marrow (BM) mesenchymal stromal cells (MSC) protect malignant cells from drug-induced cytotoxicity. However, less is known about malignant impact on supportive stroma. Notably, it is unknown whether these interactions alter long-term genotoxic damage in either direction. The nucleoside analogue cytarabine (ara-C), common in haematological therapies, remains the most effective agent for acute myeloid leukaemia, yet one-third of patients develop resistance. This study aimed to evaluate the bidirectional effect of MSC and malignant cell co-culture on ara-C genotoxicity modulation. Primary MSC, isolated from patient BM aspirates for haematological investigations, and malignant haematopoietic cells (leukaemic HL-60) were co-cultured using trans-well inserts, prior to treatment with physiological dose ara-C. Co-culture genotoxic effects were assessed by micronucleus and alkaline comet assays. Patient BM cells from chemotherapy-treated patients had reduced ex vivo survival (P = 0.0049) and increased genotoxicity (P = 0.3172) than untreated patients. It was shown for the first time that HL-60 were protected by MSC from ara-C-induced genotoxicity, with reduced MN incidence in co-culture as compared to mono-culture (P = 0.0068). Comet tail intensity also significantly increased in ara-C-treated MSC with HL-60 influence (P = 0.0308). MSC sensitisation to ara-C genotoxicity was also demonstrated following co-culture with HL60 (P = 0.0116), which showed significantly greater sensitisation when MSC-HL-60 co-cultures were exposed to ara-C (P = 0.0409). This study shows for the first time that malignant HSC and MSC bidirectionally modulate genotoxicity, providing grounding for future research identifying mechanisms of altered genotoxicity in leukaemic microenvironments. MSC retain long-term genotoxic and functional damage following chemotherapy exposure. Understanding the interactions perpetuating such damage may inform modifications to reduce therapy-related complications, such as secondary malignancies and BM failure.

中文翻译：

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与白血病 HL-60 细胞共培养的原代间充质基质细胞对阿糖胞苷诱导的基因毒性敏感，而白血病细胞受到保护

肿瘤微环境是许多癌症类型的标志。在血液系统恶性肿瘤中，骨髓 (BM) 间充质基质细胞 (MSC) 保护恶性细胞免受药物诱导的细胞毒性。然而，对支持性基质的恶性影响知之甚少。值得注意的是，尚不清楚这些相互作用是否会改变任一方向的长期基因毒性损害。核苷类似物阿糖胞苷 (ara-C) 在血液治疗中很常见，仍然是治疗急性髓系白血病最有效的药物，但仍有三分之一的患者产生耐药性。本研究旨在评估 MSC 和恶性细胞共培养对 ara-C 基因毒性调节的双向作用。从患者 BM 抽吸物中分离出的原代 MSC，用于血液学检查，在用生理剂量ara-C处理之前，使用跨孔插入物共培养和恶性造血细胞（白血病HL-60）。通过微核和碱性彗星试验评估了共培养的遗传毒性效应。与未经治疗的患者相比，来自化疗治疗患者的患者 BM 细胞离体存活率降低 (P = 0.0049)，遗传毒性增加 (P = 0.3172)。首次表明 MSC 保护 HL-60 免受 ara-C 诱导的基因毒性，与单一培养相比，共培养中的 MN 发生率降低（P = 0.0068）。具有 HL-60 影响的 ara-C 处理的 MSC 中彗尾强度也显着增加（P = 0.0308）。与 HL60 共培养后，MSC 对 ara-C 基因毒性也有敏感性（P = 0.0116），当 MSC-HL-60 共培养物暴露于 ara-C (P = 0.0409) 时，它表现出显着更高的致敏性。这项研究首次表明恶性 HSC 和 MSC 双向调节基因毒性，为未来研究确定白血病微环境中基因毒性改变的机制奠定了基础。MSC 在化疗暴露后保留长期的基因毒性和功能损伤。了解使这种损害持续存在的相互作用可能有助于减少与治疗相关的并发症，例如继发性恶性肿瘤和 BM 失败。MSC 在化疗暴露后保留长期的基因毒性和功能损伤。了解使这种损害持续存在的相互作用可能有助于减少与治疗相关的并发症，例如继发性恶性肿瘤和 BM 失败。MSC 在化疗暴露后保留长期的基因毒性和功能损伤。了解使这种损害持续存在的相互作用可能有助于减少与治疗相关的并发症，例如继发性恶性肿瘤和 BM 失败。