Systemic presence and tumor-growth promoting effect of ovarian carcinoma released exosomes.
ABSTRACT Exosomes are membrane vesicles that are released from many different cell types. Tumor derived-exosomes play a role in immune suppression. We hypothesized that in ovarian carcinoma patients exosomes initially produced at the local abdominal site may become systemic. We examined paired samples of ascites and blood from ovarian carcinoma patients for the presence of exosomes. We also studied the requirements for exosomal uptake by immune cells, the role of phosphatidyl-serine (PS) as uptake signal and the effect of exosome application on tumor growth. We used exosomes from ovarian carcinoma cell lines, malignant ascites and sera from ovarian carcinoma patients isolated by ultracentrifugation. PS-displayed by exosomes was detected by Anexin-V-FITC staining of latex beads adsorbed exosomes. For uptake experiments, labeled exosomes were exposed to cells in the presence or absence of cold Annexin-V as competitor. Uptake was examined by fluorescent microscopy and cytofluorographic analysis. Effects of exosomes on tumor growth were studied using SKOV3ip ovarian carcinoma cells in CD1 nu/nu mice. We found that malignant ascites-derived exosomes cargo tumor progression related proteins such as L1CAM, CD24, ADAM10, and EMMPRIN. We observed that exosomes become systemic via the blood stream. Uptake of ovarian carcinoma exosomes by NK cells was found to require PS at the exosomal surface but the presence of PS was not sufficient. Application of malignant ascites-derived exosomes to tumor bearing mice resulted in augmented tumor growth. Exosomes from the serum of tumor patients could be isolated from only one ml of blood and this analysis could serve for diagnostic purposes. We propose that tumor-derived exosomes could play a role in tumor progression.
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ABSTRACT: Extracellular vesicles (EVs) have been shown to transfer various molecules, including functional RNA between cells and this process has been suggested to be particularly relevant in tumor-host interactions. However, data on EV-mediated RNA transfer has been obtained primarily by in vitro experiments or involving ex vivo manipulations likely affecting its biology, leaving their physiological relevance unclear. We engineered glioma and carcinoma tumor cells to express Cre recombinase showing their release of EVs containing Cre mRNA in various EV subfractions including exosomes. Transplantation of these genetically modified tumor cells into mice with a Cre reporter background leads to frequent recombination events at the tumor site. In both tumor models the majority of recombined cells are CD45+ leukocytes, predominantly Gr1+CD11b+ myeloid-derived suppressor cells (MDSCs). In addition, multiple lineages of recombined cells can be observed in the glioma model. In the lung carcinoma model, recombined MDSCs display an enhanced immunosuppressive phenotype and an altered miRNA profile compared to their non-recombined counterparts. Cre-lox based tracing of tumor EV RNA transfer in vivo can therefore be used to identify individual target cells in the tumor microenvironment for further mechanistical or functional analysis.OncoImmunology 05/2015; DOI:10.1080/2162402X.2015.1008371 · 6.28 Impact Factor
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ABSTRACT: Exosomes are 30–120 nm endocytic membrane-derived vesicles that participate in cell-to-cell communication and protein and RNA delivery. Exosomes harbor a variety of proteins, nucleic acids, and lipids and are present in many and perhaps all bodily fluids. A significant body of literature has demonstrated that molecular constituents of exosomes, especially exosomal proteins and microRNAs (miRNAs), hold great promise as novel biomarkers for clinical diagnosis. In this minireview, we summarize recent advances in the research of exosomal biomarkers and their potential application in clinical diagnostics. We also provide a brief overview of the formation, function, and isolation of exosomes.01/2015; 2015. DOI:10.1155/2015/657086
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ABSTRACT: Exosomes contain cargo material from endosomes, cytosol, plasma membrane and microRNA molecules, they are released by a number of non-cancer and cancer cells into both the extracellular microenvironment and body fluids such as blood plasma. Recently we demonstrated radiation-induced non-targeted effects [NTE: genomic instability (GI) and bystander effects (BE)] are partially mediated by exosomes, particularly the RNA content. However the mechanistic role of exosomes in NTE is yet to be fully understood. The present study used MCF7 cells to characterise the longevity of exosome-induced activity in the progeny of irradiated and unirradiated bystander cells. Exosomes extracted from conditioned media of irradiated and bystander progeny were added to unirradiated cells. Analysis was carried out at 1 and 20/24 population doublings following medium/exosome transfer for DNA/chromosomal damage. Results confirmed exosomes play a significant role in mediating NTE of ionising radiation (IR). This effect was remarkably persistent, observed >20 doublings post-irradiation in the progeny of bystander cells. Additionally, cell progeny undergoing a BE were themselves capable of inducing BE in other cells via exosomes they released. Furthermore we investigated the role of exosome cargo. Culture media from cells exposed to 2Gy X-rays was subjected to ultracentrifugation and four inoculants prepared, (a) supernatants with exosomes removed, and pellets with (b) exosome proteins denatured, (c) RNA degraded, and (d) a combination of protein-RNA inactivation. These were added to separate populations of unirradiated cells. The BE was partially inhibited when either exosome protein or exosome RNA were inactivated separately, whilst combined RNA-protein inhibition significantly reduced or eliminated the BE. These results demonstrate that exosomes are associated with long-lived signalling of the NTE of IR. Both RNA and protein molecules of exosomes work in a synergistic manner to initiate NTE, spread these effects to naïve cells, and perpetuate GI in the affected cells. Copyright © 2015. Published by Elsevier B.V.Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 02/2015; 772:38-45. DOI:10.1016/j.mrfmmm.2014.12.007 · 4.44 Impact Factor