Muller Laurent, Simms Patricia, Hong Chang-Sook, Nishimura Michael I, Jackson Edwin K, Watkins Simon C, Whiteside Theresa L
Department of Otolaryngology and Head and Neck Surgery, University Hospital Basel, Switzerland.
University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA.
Oncoimmunology. 2017 Jul 19;6(8):e1261243. doi: 10.1080/2162402X.2016.1261243. eCollection 2017.
Tumor-derived exosomes (TEX) are ubiquitously present in the tumor microenvironment and plasma of cancer patients. TEX carry a cargo of multiple stimulatory and inhibitory molecules and deliver them to recipient cells, serving as a communication network for the tumor. The mechanisms TEX use for delivering messages to recipient cells were evaluated using PKH26-labeled TEX produced by cultured human tumor cells, exosomes produced by dendritic cells-derived exosomes (DEX), or exosomes isolated from plasma of cancer patients (EXO). Human T-cell subsets, B cells, NK cells, and monocytes were co-incubated with TEX, DEX, or EXO and binding or internalization of labeled vesicles was evaluated by confocal microscopy and/or Amnis-based flow cytometry. Vesicle-induced Ca influx in recipient T cells was monitored, and TEX-induced inosine production in Treg was determined by mass spectrometry. In contrast to B cells, NK cells or monocytes, conventional T cells did not internalize labeled vesicles. Minimal exosome uptake was only evident in Treg following prolonged co-incubation with TEX. All exosomes induced Ca influx in T cells, with TEX and EXO isolated from cancer patients' plasma delivering the strongest, sustained signaling to Treg. Such sustained signaling resulted in the significant upregulation of the conversion of extracellular ATP to inosine (adenosine metabolite) by Treg, suggesting that TEX signaling could have functional consequences in these recipient cells. Thus, modulation of Treg suppressor functions by TEX is mediated by mechanisms dependent on cell surface signaling and does not require TEX internalization by recipient cells.
肿瘤衍生外泌体（TEX）普遍存在于癌症患者的肿瘤微环境和血浆中。TEX携带多种刺激和抑制分子，并将它们传递给受体细胞，充当肿瘤的通信网络。使用培养的人肿瘤细胞产生的PKH26标记的TEX、树突状细胞衍生外泌体（DEX）产生的外泌体或从癌症患者血浆中分离的外泌体（EXO）来评估TEX向受体细胞传递信息的机制。将人T细胞亚群、B细胞、NK细胞和单核细胞与TEX、DEX或EXO共同孵育，并通过共聚焦显微镜和/或基于Amnis的流式细胞术评估标记囊泡的结合或内化情况。监测囊泡诱导的受体T细胞中的Ca内流，并通过质谱法测定TEX诱导的调节性T细胞（Treg）中肌苷的产生。与B细胞、NK细胞或单核细胞不同，传统T细胞不会内化标记的囊泡。只有在与TEX长时间共同孵育后，Treg中才明显出现最小程度的外泌体摄取。所有外泌体均诱导T细胞中的Ca内流，从癌症患者血浆中分离的TEX和EXO向Treg传递最强、持续的信号。这种持续的信号导致Treg将细胞外ATP转化为肌苷（腺苷代谢物）的转化率显著上调，表明TEX信号可能在这些受体细胞中产生功能后果。因此，TEX对Treg抑制功能的调节是由依赖于细胞表面信号的机制介导的，不需要受体细胞内化TEX。
