Yerrapragada Sri Meghana, Alex Aleena, Adar Sheera, Kemp Michael G, Carpenter M Alexandra
Department of Pharmacology and Toxicology, Wright State University Boonshoft School of Medicine, Dayton, OH, USA.
Department of Microbiology and Molecular Genetics, The Institute for Medical Research-Canada, The Faculty of Medicine, The Hebrew University of Jersusalem, Jersualem, Israel.
DNA Repair (Amst). 2025 Jul;151:103855. doi: 10.1016/j.dnarep.2025.103855. Epub 2025 Jun 12.
Cell-free DNA (cfDNA) found in biofluids is increasingly being used in the diagnosis and treatment of a variety of disease states, including cancer. Though DNA is known to be susceptible to damage by many different chemotherapeutic compounds and genotoxic agents, the fact that cfDNA may be damaged and contain DNA adducts associated with specific exposures has not previously been considered to any significant extent. Here, using differential centrifugation of culture medium from cells treated with the anti-cancer drug cisplatin, we show that DNA containing cisplatin adducts is readily detectable in the extracellular milieu and is enriched in fractions known to contain small extracellular vesicles and cfDNA. However, our data indicates that this damaged cfDNA is non-vesicular in nature and likely represents fragments of chromatin. Dose and time course experiments suggest that the release of cfDNA containing cisplatin-DNA adducts is correlated with the activation of apoptotic signaling. Indeed, the generation of cisplatin-damaged cfDNA is exacerbated by the loss of nucleotide excision repair and is abrogated by caspase inhibition. Finally, we show that native cisplatin-damaged cfDNA, but not purified, protein-free cfDNA, can be taken up by cells by phagocytosis to result in the presence of cisplatin-DNA adduct-containing DNA in non-cisplatin-treated cells. These results indicate that tumors from patients undergoing cisplatin-based chemotherapy may shed damaged cfDNA that could have additional biological effects in bystander cells, which could both impact chemotherapeutic responses and lead to improved treatments and diagnostic tools for monitoring therapeutic efficacy.
生物流体中发现的游离DNA（cfDNA）越来越多地用于多种疾病状态的诊断和治疗，包括癌症。尽管已知DNA易受许多不同化疗化合物和基因毒性剂的损伤，但cfDNA可能受损并含有与特定暴露相关的DNA加合物这一事实以前在很大程度上未被考虑。在这里，我们通过对用抗癌药物顺铂处理的细胞的培养基进行差速离心，表明含有顺铂加合物的DNA在细胞外环境中很容易被检测到，并且在已知含有小细胞外囊泡和cfDNA的组分中富集。然而，我们的数据表明，这种受损的cfDNA本质上是非囊泡性的，可能代表染色质片段。剂量和时间进程实验表明，含有顺铂-DNA加合物的cfDNA的释放与凋亡信号的激活相关。事实上，核苷酸切除修复的丧失会加剧顺铂损伤的cfDNA的产生，而半胱天冬酶抑制则可消除这种产生。最后，我们表明，天然的顺铂损伤的cfDNA，而不是纯化的、无蛋白的cfDNA，可以被细胞通过吞噬作用摄取，导致未用顺铂处理的细胞中存在含有顺铂-DNA加合物的DNA。这些结果表明，接受基于顺铂化疗的患者的肿瘤可能会释放受损的cfDNA，这可能会对旁观者细胞产生额外的生物学效应，这既可能影响化疗反应，也可能导致改进治疗方法和监测治疗效果的诊断工具。
