Cancer-derived extracellular vesicles (EVs) are membrane-enclosed structures of highly variable size. EVs contain a myriad of substances (proteins, lipid, RNA, DNA) that provide a reservoir of circulating molecules, thus offering a good source of biomarkers. We demonstrate here that large EVs (L-EV) (large oncosomes) isolated from prostate cancer (PCa) cells and patient plasma are an EV population that is enriched in chromosomal DNA, including large fragments up to 2 million base pair long. While L-EVs and small EVs (S-EV) (exosomes) isolated from the same cells contained similar amounts of protein, the DNA was more abundant in L-EVs, despite S-EVs being more numerous. Consistent with in vitro observations, the abundance of DNA in L-EV obtained from PCa patient plasma was variable but frequently high. Conversely, negligible amounts of DNA were present in the S-EVs from the same patients. Controlled experimental conditions, with spike-ins of L-EVs and S-EVs from cancer cells in human plasma from healthy subjects, showed that circulating DNA is almost exclusively enclosed in L-EVs. Whole genome sequencing revealed that the DNA in L-EVs reflects genetic aberrations of the cell of origin, including copy number variations of genes frequently altered in metastatic PCa (i.e. MYC, AKT1, PTK2, KLF10 and PTEN). These results demonstrate that L-EV-derived DNA reflects the genomic make-up of the tumour of origin. They also support the conclusion that L-EVs are the fraction of plasma EVs with DNA content that should be interrogated for tumour-derived genomic alterations.

癌症来源的细胞外囊泡（EVs）是高度可变的膜封闭结构。电动汽车包含多种物质（蛋白质，脂质，RNA，DNA），这些物质提供了循环分子的储存库，因此提供了良好的生物标志物来源。我们在此证明，从前列腺癌（PCa）细胞和患者血浆中分离出的大型EV（L-EV）（大型癌体）是一种富含染色体DNA的EV群体，包括长达200万碱基对的大片段。从同一细胞中分离出的L-EV和小型EV（S-EV）（外泌体）含有相似量的蛋白质，尽管S-EV数量众多，但L-EV中的DNA却更为丰富。与体外一致观察发现，从PCa患者血浆中获得的L-EV中DNA的丰度是可变的，但通常很高。相反，来自相同患者的S-EV中存在少量DNA。在健康受试者的血浆中刺入L-EV和S-EV的受控实验条件表明，循环DNA几乎完全封闭在L-EV中。全基因组测序表明，L-EV中的DNA反映了起源细胞的遗传畸变，包括在转移性PCa中经常改变的基因（即MYC，AKT1，PTK2，KLF10和PTEN）的拷贝数变异）。这些结果表明，L-EV衍生的DNA反映了起源肿瘤的基因组组成。他们还支持以下结论：L-EV是具有DNA含量的血浆EV的一部分，应针对肿瘤衍生的基因组改变进行询问。