Fast and specific enrichment of cancer-related exosomes by DNA-nanoweight-assisted centrifugation

Exosomes are nanoscale membrane vesicles actively released by cells and play an important role in the diagnosis of cancer-related diseases. However, it is challenging to efficiently enrich exosomes from extracellular fluids. In this work, we used DNA-tetrahedron as a nanoweight during centrifugation to precisely enrich tumor exosomes from a complex biological environment. Two different DNA tetrahedral nanostructures (DTAs), each carrying a specific aptamer for exosome biomarker recognition, were incubated with clinical samples simultaneously. One DTA triggered the cross-linking of multiple target exosomes, and therefore enabled low-speed and fast centrifugation for enrichment. The other DTA further narrowed down the target exosome subtype and initiated a hybridization chain reaction (HCR) for sensitive signal amplification. The method enabled the detection of 180 MCF-7-derived exosomes per microliter and 560 HepG2-derived exosomes per microliter, with 1000-fold higher sensitivity than conventional ELISA. This easy-to-operate method can enrich exosomes with excellent specificity and therefore will be appealing in biomedical research and clinical diagnosis.

Dissecting the multi-omics atlas of the exosomes released by human lung adenocarcinoma stem-like cells

Lung adenocarcinoma is heterogeneous and hierarchically organized, with a subpopulation of stem-like cells (CSCs) that reside at the apex of the hierarchy, in which exosomes act as important mediators by transporting specific molecules among different cell populations. Although there have been numerous studies on tumor exosomes, the constituents and functional properties of CSC-derived exosomes are still poorly characterized. Here we present a detail transcriptome and proteome atlas of the exosomes released by human lung adenocarcinoma stem-like cells (LSLCs). The transcriptome analysis indicates the specific patterns of exosomal constituents, including the fragmentation of transcripts and the low-level presence of circular RNAs, and identifies multiple exosomal-enriched mRNAs and lncRNAs. Integrative analysis of transcriptome and proteome data reveals the diverse functions of exosomal-enriched RNAs and proteins, many of which are associated with tumorigenesis. Importantly, several LSLC markers we identified are highly expressed in LSLC-derived exosomes and associate with poor survival, which may serve as promising liquid biopsy biomarkers for lung adenocarcinoma diagnosis. Our study provides a resource for the future elucidation of the functions of tumor-derived exosomes and their regulatory mechanisms in mediating lung cancer development.

Pro-Inflammatory Microenvironment Modulates the Transfer of Mutated TP53 Mediated by Tumor Exosomes

Exosomes released from tumor cells are instrumental in shaping the local tumor microenvironment to allow cancer progression. Recently, it has been shown that tumor exosomes carry large fragments of dsDNA, which may reflect the mutational status of parental cells. Although it has been described that a stressful microenvironment can influence exosomal cargo, the effects on DNA packing and its transfer into recipient cells have yet to be investigated. Here, we report that exosomes derived from SW480 (human colorectal adenocarcinoma cell line) cells can carry dsDNA fragments containing the entire coding sequence of both TP53 and KRAS genes, harboring the SW480-related TP53 c.818G > A and KRAS c.35G > T typical mutations. We also report the following: that cell stimulation with lipopolysaccharides (LPS) promotes the selective packaging of the TP53 gene, but not the KRAS gene; that exosomes secreted by SW480 cells efficiently transfer the mutated sequences into normal CCD841-CoN colon epithelial and THLE-2 hepatic cells; that this mechanism is more efficient when the cells had been previously incubated with pro-inflammatory cytokines; that the TP53 gene appears actively transcribed in both recipient cells; and that mutated mRNA levels are not influenced by cytokine treatment. Our data strongly suggest that pro-inflammatory stimulation promotes the horizontal transfer of an oncogene by exosomes, although this remains a rare event. Further studies are needed to assess the impact of the oncogenic transfer by exosomes in malignant transformation and its role in tumor progression.

The roles of tumor-derived exosomes in altered differentiation, maturation and function of dendritic cells

Tumor-derived exosomes (TDEs) have been shown to impede anti-tumor immune responses via their immunosuppressive cargo. Since dendritic cells (DCs) are the key mediators of priming and maintenance of T cell-mediated responses; thus it is logical that the exosomes released by tumor cells can exert a dominant influence on DCs biology. This paper intends to provide a mechanistic insight into the TDEs-mediated DCs abnormalities in the tumor context. More importantly, we discuss extensively how tumor exosomes induce subversion of DCs differentiation, maturation and function in separate sections. We also briefly describe the importance of TDEs at therapeutic level to help guide future treatment options, in particular DC-based vaccination strategy, and review advances in the design and discovery of exosome inhibitors. Understanding the exosomal content and the pathways by which TDEs are responsible for immune evasion may help to revise treatment rationales and devise novel therapeutic approaches to overcome the hurdles in cancer treatment.

Targeting Tumor-derived exosomes expressing CD73: new opportunities in the pathogenesis and treatment of cancer

: Tumor-derived exosomes contain biological contents such as proteins, lipids, RNA (miRNAs, mRNAs, lncRNA), and DNA for intracellular communication. Meanwhile, studies have shown the role of exosomes in cancer progression, metastasis, and therapeutic resistance. Furthermore, tumor exosomes have received growing attention due to their potential as novel therapeutic protocols for the treatment of cancers. Adenosine nucleoside, which is a derivative of ATP, is highly elevated in the tumor microenvironment by CD39 and CD73 enzymatic activity. Recently, it is distinguished that cancer cellderived exosomes carry CD39 and CD73 on their surface and may contribute to rising adenosine levels in the tumor microenvironment. In this review, we summarize the evidence of CD39/CD73-bearing exosomes and their role in cancer development, progression, invasion, angiogenesis, metastasis and their application in the selection of the appropriate strategy to treat different types of cancer.

The Influence of a Stressful Microenvironment on Tumor Exosomes: A Focus on the DNA Cargo

Exosomes secreted by tumor cells, through the transport of bioactive molecules, reprogram the surroundings, building a microenvironment to support the development of the tumor. The discovery that exosomes carry genomic DNA reflecting that of the tumor cell of origin has encouraged studies to use them as non-invasive biomarkers. The exosome-mediated transfer of oncogenes suggested a new mechanism of malignant transformation that could play a role in the formation of metastases. Several studies have examined the role of tumor exosomes on the modulation of the tumor microenvironment, but relatively few have been directed to assess how stressful stimuli can influence their production and cargo. Understanding the changes in exosome loads and the production pattern of the stressed tumor cell may uncover actionable mechanisms responsible for tumor progression.