Hornick Noah I, Doron Ben, Abdelhamed Sherif, Huan Jianya, Harrington Christina A, Shen Rongkun, Cambronne Xiaolu A, Chakkaramakkil Verghese Santhosh, Kurre Peter
Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA. Pediatric Cancer Biology, Oregon Health & Science University, Portland, OR 97239, USA. Papé Family Pediatric Research Institute, Oregon Health & Science University, Portland, OR 97239, USA.
Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA. Pediatric Cancer Biology, Oregon Health & Science University, Portland, OR 97239, USA. Knight Cancer Institute, Oregon Health & Science University, Portland, OR 97239, USA.
Sci Signal. 2016 Sep 6;9(444):ra88. doi: 10.1126/scisignal.aaf2797.
Exosomes are paracrine regulators of the tumor microenvironment and contain complex cargo. We previously reported that exosomes released from acute myeloid leukemia (AML) cells can suppress residual hematopoietic stem and progenitor cell (HSPC) function indirectly through stromal reprogramming of niche retention factors. We found that the systemic loss of hematopoietic function is also in part a consequence of AML exosome-directed microRNA (miRNA) trafficking to HSPCs. Exosomes isolated from cultured AML or the plasma from mice bearing AML xenografts exhibited enrichment of miR-150 and miR-155. HSPCs cocultured with either of these exosomes exhibited impaired clonogenicity, through the miR-150- and miR-155-mediated suppression of the translation of transcripts encoding c-MYB, a transcription factor involved in HSPC differentiation and proliferation. To discover additional miRNA targets, we captured miR-155 and its target transcripts by coimmunoprecipitation with an attenuated RNA-induced silencing complex (RISC)-trap, followed by high-throughput sequencing. This approach identified known and previously unknown miR-155 target transcripts. Integration of the miR-155 targets with information from the protein interaction database STRING revealed proteins indirectly affected by AML exosome-derived miRNA. Our findings indicate a direct effect of AML exosomes on HSPCs that, through a stroma-independent mechanism, compromises hematopoiesis. Furthermore, combining miRNA target data with protein-protein interaction data may be a broadly applicable strategy to define the effects of exosome-mediated trafficking of regulatory molecules within the tumor microenvironment.
外泌体是肿瘤微环境的旁分泌调节因子，且包含复杂的货物分子。我们之前报道过，急性髓系白血病（AML）细胞释放的外泌体可通过对龛位保留因子进行基质重编程，间接抑制残留造血干祖细胞（HSPC）的功能。我们发现，造血功能的系统性丧失部分也是AML外泌体介导的微小RNA（miRNA）转运至HSPC的结果。从培养的AML中分离出的外泌体或荷AML异种移植小鼠的血浆中均显示出miR-150和miR-155的富集。与这些外泌体中的任何一种共培养的HSPC表现出克隆形成能力受损，这是通过miR-150和miR-155介导的对编码c-MYB的转录本翻译的抑制实现的，c-MYB是一种参与HSPC分化和增殖的转录因子。为了发现更多的miRNA靶点，我们通过与减毒的RNA诱导沉默复合体（RISC）捕获器进行免疫共沉淀来捕获miR-155及其靶转录本，随后进行高通量测序。该方法鉴定出了已知和先前未知的miR-155靶转录本。将miR-155靶点与来自蛋白质相互作用数据库STRING的信息整合，揭示了受AML外泌体衍生的miRNA间接影响的蛋白质。我们的研究结果表明，AML外泌体对HSPC有直接影响，通过一种不依赖基质的机制损害造血功能。此外，将miRNA靶点数据与蛋白质-蛋白质相互作用数据相结合，可能是一种广泛适用的策略，用于定义肿瘤微环境中调节分子的外泌体介导的转运作用。
