Montreal Children's Hospital, Research Institute of McGill University Health Centre, McGill University, Montreal, Quebec, Canada.
McGill University and Genome Quebec Innovation Centre, Montreal, Quebec, Canada.
Biochem Biophys Res Commun. 2014 Aug 22;451(2):295-301. doi: 10.1016/j.bbrc.2014.07.109. Epub 2014 Jul 30.
Cell free DNA is often regarded as a source of genetic cancer biomarkers, but the related mechanisms of DNA release, composition and biological activity remain unclear. Here we show that rat epithelial cell transformation by the human H-ras oncogene leads to an increase in production of small, exosomal-like extracellular vesicles by viable cancer cells. These EVs contain chromatin-associated double-stranded DNA fragments covering the entire host genome, including full-length H-ras. Oncogenic N-ras and SV40LT sequences were also found in EVs emitted from spontaneous mouse brain tumor cells. Disruption of acidic sphingomyelinase and the p53/Rb pathway did not block emission of EV-related oncogenic DNA. Exposure of non-transformed RAT-1 cells to EVs containing mutant H-ras DNA led to the uptake and retention of this material for an extended (30days) but transient period of time, and stimulated cell proliferation. Thus, our study suggests that H-ras-mediated transformation stimulates vesicular emission of this histone-bound oncogene, which may interact with non-transformed cells.
无细胞 DNA 通常被视为遗传癌症生物标志物的来源，但 DNA 释放、组成和生物活性的相关机制尚不清楚。在这里，我们表明，人类 H-ras 癌基因使大鼠上皮细胞发生转化，导致活癌细胞产生更多的小的、外泌体样细胞外囊泡。这些 EV 包含染色质相关的双链 DNA 片段，覆盖整个宿主基因组，包括全长 H-ras。从自发产生的小鼠脑肿瘤细胞释放的 EV 中也发现了致癌 N-ras 和 SV40LT 序列。酸性鞘磷脂酶和 p53/Rb 通路的破坏并没有阻止 EV 相关致癌 DNA 的释放。将含有突变 H-ras DNA 的 EV 暴露于非转化的 RAT-1 细胞中，导致该物质的摄取和保留延长（30 天）但短暂的时间，并刺激细胞增殖。因此，我们的研究表明，H-ras 介导的转化刺激这种与组蛋白结合的致癌基因的囊泡释放，这可能与非转化细胞相互作用。
