Tumor-derived exosomes in cancer metastasis risk diagnosis and metastasis therapy

Exosome-mediated renal protection: Halting the progression of fibrosis

Renal fibrosis is a complex and multifactorial process that involves inflammation, cell proliferation, collagen, and fibronectin deposition in the kidney, ultimately leading to chronic kidney disease and even end-stage renal disease. The main goal of treatment is to slow down or halt the progression of fibrosis and to improve or preserve kidney function. Despite significant progress made in understanding the underlying mechanisms of renal fibrosis, current therapies have limited renal protection as the disease progresses. Exosomes derived from stem cells are a newer area of research for the treatment of renal fibrosis. Exosomes as nano-sized extracellular vesicles carry proteins, lipids, and nucleic acids, which can be taken up by local or distant cells, serving as mediators of intercellular communication and as drug delivery vehicles. Exosomes deliver molecules that reduce inflammation, renal fibrosis and extracellular matrix protein production, and promote tissue regeneration in animal models of kidney disease. Additionally, they have several advantages over stem cells, such as being non-immunogenic, having low risk of tumor formation, and being easier to produce and store. This review describes the use of natural and engineered exosomes containing therapeutic agents capable of mediating anti-inflammatory and anti-fibrotic processes during both acute kidney injury and chronic kidney disease. Exosome-based therapies will be compared with stem cell-based treatments for tissue regeneration, with a focus on renal protection. Finally, future directions and strategies for improving the therapeutic efficacy of exosomes are discussed.

Tumor Microenvironment Modulation by Cancer-Derived Extracellular Vesicles

The tumor microenvironment (TME) plays an important role in the process of tumorigenesis, regulating the growth, metabolism, proliferation, and invasion of cancer cells, as well as contributing to tumor resistance to the conventional chemoradiotherapies. Several types of cells with relatively stable phenotypes have been identified within the TME, including cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), neutrophils, and natural killer (NK) cells, which have been shown to modulate cancer cell proliferation, metastasis, and interaction with the immune system, thus promoting tumor heterogeneity. Growing evidence suggests that tumor-cell-derived extracellular vesicles (EVs), via the transfer of various molecules (e.g., RNA, proteins, peptides, and lipids), play a pivotal role in the transformation of normal cells in the TME into their tumor-associated protumorigenic counterparts. This review article focuses on the functions of EVs in the modulation of the TME with a view to how exosomes contribute to the transformation of normal cells, as well as their importance for cancer diagnosis and therapy.

Hypoxic nasopharyngeal carcinoma-derived exosomal miR-455 increases vascular permeability by targeting ZO-1 to promote metastasis

Nasopharyngeal carcinoma (NPC), the most frequent reason for treatment failure in head and neck tumors, has the greatest incidence of distant metastases. Increased vascular permeability facilitates metastasis. Exosomal microRNAs (miRNAs) have been implicated in the development of the premetastatic niche and are emerging as prospective biomarkers in cancer patients. We discovered that a higher level of miR-455 was connected to a larger propensity for NPC metastasis based on deep sequencing and RT-qPCR. We found that hypoxia promoted NPC exosomes release and increased miR-455 expression in a way that was hypoxia-inducible factor 1-alpha (HIF-1α) dependent. Exosomes from NPC cells with high levels of miR-455 were found to specifically target zonula occludens 1 (ZO-1), increasing the permeability of endothelial monolayers in vitro vascular permeability and transendothelial invasion experiments. Additional in vivo studies showed that zebrafish with sustained miR-455-overexpressing NPC cell xenografts displayed increased tumor cell mass throughout the body. In vivo, zebrafish vascular tight junction integrity was disrupted by exosomes produced by NPC cells with elevated miR-455 expression. Mice-bearing xenografts further supported the finding that exosomes containing miR-455 might reduce ZO-1 expression in addition to promote NPC cell growth. These findings suggest that in a hypoxic microenvironment, exosomal miR-455 released by NPC cells enhances vascular permeability and promotes metastasis by targeting ZO-1. The HIF-1α-miR-455-ZO-1 signaling pathway may be a promising predictor and potential therapeutic target for NPC with metastasis.

Blood-Derived Extracellular Vesicle-Associated miR-3182 Detects Non-Small Cell Lung Cancer Patients

Simple Summary

Lung cancer is the leading cause of cancer-related death worldwide as patients are burdened with incredibly poor prognosis. Low survival rates are primarily attributed to lack of early detection and, therefore, timely therapeutic interventions. Late diagnosis is essentially caused by absent and non-specific symptoms, and compounded by inadequate diagnostic tools. We show here that a lung cancer biomarker, based on a simple blood test, might provide promising advantages for diagnostic assessment. Small extracellular vesicles (sEVs) are miniscule messengers that carry cancer biomarkers and are easily detected in the blood. We identify that the abundance of a specific micro-RNA, miR-3182, in these sEVs can be detected in the blood of lung cancer patients but not in controls with benign lung conditions. This demonstrates the potential use of miR-3182 as a biomarker for lung cancer diagnosis.

Abstract

With five-year survival rates as low as 3%, lung cancer is the most common cause of cancer-related mortality worldwide. The severity of the disease at presentation is accredited to the lack of early detection capacities, resulting in the reliance on low-throughput diagnostic measures, such as tissue biopsy and imaging. Interest in the development and use of liquid biopsies has risen, due to non-invasive sample collection, and the depth of information it can provide on a disease. Small extracellular vesicles (sEVs) as viable liquid biopsies are of particular interest due to their potential as cancer biomarkers. To validate the use of sEVs as cancer biomarkers, we characterised cancer sEVs using miRNA sequencing analysis. We found that miRNA-3182 was highly enriched in sEVs derived from the blood of patients with invasive breast carcinoma and NSCLC. The enrichment of sEV miR-3182 was confirmed in oncogenic, transformed lung cells in comparison to isogenic, untransformed lung cells. Most importantly, miR-3182 can successfully distinguish early-stage NSCLC patients from those with benign lung conditions. Therefore, miR-3182 provides potential to be used for the detection of NSCLC in blood samples, which could result in earlier therapy and thus improved outcomes and survival for patients.

Beyond DNA-targeting in Cancer Chemotherapy. Emerging Frontiers - A Review

Modern anti-cancer drugs target DNA specifically for rapid division of malignant cells. One downside of this approach is that they also target other rapidly dividing healthy cells, such as those involved in hair growth leading to serious toxic side effects and hair loss. Therefore, it would be better to develop novel agents that address cellular signaling mechanisms unique to cancerous cells, and new research is now focussing on such approaches. Although the classical chemotherapy area involving DNA as the set target continues to produce important findings, nevertheless, a distinctly discernible emerging trend is the divergence from the cisplatin operation model that uses the metal as the primary active center of the drug. Many successful anti-cancer drugs present are associated with elevated toxicity levels. Cancers also develop immunity against most therapies and the area of cancer research can, therefore, be seen as an area with a high unaddressed need. Hence, ongoing work into cancer pathogenesis is important to create accurate preclinical tests that can contribute to the development of innovative drugs to manage and treat cancer. Some of the emergent frontiers utilizing different approaches include nanoparticles delivery, use of quantum dots, metal complexes, tumor ablation, magnetic hypothermia and hyperthermia by use of Superparamagnetic Iron oxide Nanostructures, pathomics and radiomics, laser surgery and exosomes. This review summarizes these new approaches in good detail, giving critical views with necessary comparisons. It also delves into what they carry for the future, including their advantages and disadvantages.

Exosomes: From garbage bins to translational medicine

Exosomes are lipid bilayer-enclosed vesicles of endosomal origin, which initially considered as garbage bins to dispose unwanted cellular components, but they are now emerged as an intercellular communication system involved in several physiological and pathological conditions. With the increasing understanding that the healthy patients release exosomes with distinct proteins and RNAs, exosomes have been exploited as biomarkers for disease diagnosis and prognosis. Owing to the intrinsic immunomodulatory in a tumor microenvironment, exosomes have also been vaccinated into patients against malignant diseases. Moreover, the nano-metered exosomes are relatively stable in extracellular fluids. Thus they appear attractive in delivering "cargo" to destined cells with enhanced efficiency. In this review, we outline the current knowledge in exosomal biogenesis and isolation. Furthermore, the biological activities of exosomes are also discussed with a focus on their potentials to be employed in translational medicine, especially as biomarkers, vaccines and therapeutic delivery system.

Progress in Microfluidics-Based Exosome Separation and Detection Technologies for Diagnostic Applications

Exosomes are secreted by most cell types and circulate in body fluids. Recent studies have revealed that exosomes play a significant role in intercellular communication and are closely associated with the pathogenesis of disease. Therefore, exosomes are considered promising biomarkers for disease diagnosis. However, exosomes are always mixed with other components of body fluids. Consequently, separation methods for exosomes that allow high-purity and high-throughput separation with a high recovery rate and detection techniques for exosomes that are rapid, highly sensitive, highly specific, and have a low detection limit are indispensable for diagnostic applications. For decades, many exosome separation and detection techniques have been developed to achieve the aforementioned goals. However, in most cases, these two techniques are performed separately, which increases operation complexity, time consumption, and cost. The emergence of microfluidics offers a promising way to integrate exosome separation and detection functions into a single chip. Herein, an overview of conventional and microfluidics-based techniques for exosome separation and detection is presented. Moreover, the advantages and drawbacks of these techniques are compared.

Exosomes derived from Piwil2‑induced cancer stem cells transform fibroblasts into cancer‑associated fibroblasts

Recently, several studies have demonstrated that cancer cell‑derived exosomes can facilitate tumor development and metastasis formation. However, the detailed function of exosomes released by cancer stem cells (CSCs) requires further investigation. The aim of the present study was to investigate the role of CSC‑derived exosomes in tumor development. For this purpose, Piwil2‑induced cancer stem cells (Piwil2‑iCSCs) were used as exosome‑generating cells, while fibroblasts (FBs) served as recipient cells. Exosomes were isolated by the ultracentrifugation of Piwil2‑iCSC‑conditioned medium and identified by transmission electron microscopy, nanoparticle tracking analysis and western blot analysis. To evaluate the effects of the exosomes on cell proliferation, migration and invasion, cell counting assay (CCK‑8), a wound healing assay and a Transwell assay were performed. Protein expression [matrix metalloproteinase (MMP)2, MMP9, α‑smooth muscle actin (α‑SMA) and vimentin and fibroblast‑activating protein (FAP)] was examined in FBs by western blot analysis. It was found that the Piwil2‑iCSC‑derived exosomes (Piwil2‑iCSC‑Exo) were oval or spherical, membrane‑coated vesicles with a uniform size (30‑100 nm in diameter). They are characterized by the surface expression of CD9, CD63, Hsp70 and Piwil2 proteins. Additional results from functional analyses revealed that Piwil2‑iCSC‑Exo enhanced the proliferative, migratory and invasive abilities of FBs, accompanied by the upregulated expression of MMP2 and MMP9. In addition, the increased expression of α‑SMA (P<0.05), vimentin (P<0.01 vs. control group, P<0.05 vs. PBS group) and FAP (P<0.001 vs. control group, P<0.01 vs. PBS group) following exposure to Piwil2‑iCSC‑Exo suggested that the exosomes induced FB transformation into cancer‑associated fibroblasts (CAFs). On the whole, the findings of this study demonstrate that Piwil2‑iCSC‑Exo induce the cancer‑associated phenotype in fibroblasts in vitro, suggesting that CSCs can promote tumor development through the modulation of the tumor microenvironment.

Feasibility of tumor‑derived exosome enrichment in the onco‑hematology leukemic model of chronic myeloid leukemia

Due to the discovery of their role in intra-cellular communications, exosomes, which carry information specific to the cell of origin, have garnered considerable attention in cancer research. Moreover, there is evidence to suggest the possibility of isolating different exosome sub-populations based on target antigens at the cell surface. Philadelphia chromosome-positive (Ph⁺) chronic myeloid leukemia (CML) is a clonal myeloproliferative neoplasia characterized by the break-point cluster region-proto-oncogene 1 tyrosine-protein kinase (BCR-ABL1) fusion-gene, derived from the t (9;22) translocation. Tyrosine kinase inhibitors (TKIs) target BCR-ABL1 protein and induce major or deep molecular responses in the majority of patients. Despite the fact that several studies have demonstrated the persistence of leukemic cells in the bone marrow niche, even following treatment, TKIs prolong patient survival time and facilitate treatment-free remission. These characteristics render CML a plausible model for investigating the feasibility of tumor-derived exosome fraction enrichment. In the present study, patients in the chronic phase (CP) of CML were treated with TKIs, and the quantification of the BCR-ABL1 exosomal transcript was performed using digital PCR (dPCR). The possibility of tumor-derived exosomes enrichment was confirmed, and for the first time, to the best of our knowledge, the detection of the BCR-ABL1 transcript highlighted the presence of active leukemic cells in patients with CP-CML. According to these findings, tumor-derived exosomes may be considered a novel tool for the identification of active leukemic cells, and for the assessment of innovative monitoring focused on the biological functions of exosomes in CML.

MicroRNA-765 is pregulated in multiple myeloma and serves an oncogenic role by directly targeting SOX6

Increasing evidence has revealed that microRNAs (miRNAs) are closely associated with multiple myeloma (MM) pathogenesis and progression. Therefore, an in-depth understanding of the biological functions of miRNAs in MM may be helpful for the identification of promising therapeutic techniques for patients with MM. miRNA-765 (miR-765) has been reported to be dysregulated in many types of human cancer. However, the expression pattern, specific roles and underlying mechanisms of miR-765 in MM remain largely unknown. In the present study, plasma miR-765 significantly increased in patients with MM and cell lines. The downregulation of miR-765 in MM cells attenuated proliferation and promoted apoptosis. Bioinformatics analysis predicted that SRY-Box 6 (SOX6) was a putative target of miR-765. This was experimentally verified using a luciferase reporter assay, reverse transcription-quantitative PCR and western blot analysis. Furthermore, plasma SOX6 was downregulated in patients with MM and the downregulation of SOX6 was inversely correlated with that of miR-765 expression. Furthermore, SOX6 knockdown markedly abrogated the effects of miR-765 underexpression on cell proliferation and apoptosis in MM. The current study demonstrated that miR-765 serves an oncogenic role in MM progression by directly targeting SOX6, suggesting that miR-765 may be a potential therapeutic target for MM prevention and treatment.

A Role of Tumor-Released Exosomes in Paracrine Dissemination and Metastasis

Metastatic diffusion is thought to be a multi-step phenomenon involving the release of cells from the primary tumor and their diffusion through the body. Currently, several hypotheses have been put forward in order to explain the origin of cancer metastasis, including epithelial⁻mesenchymal transition, mutagenesis of stem cells, and a facilitating role of macrophages, involving, for example, transformation or fusion hybridization with neoplastic cells. In this paradigm, tumor-secreted extracellular vesicles (EVs), such as exosomes, play a pivotal role in cell communications, delivering a plethora of biomolecules including proteins, lipids, and nucleic acids. For their natural role in shuttling molecules, EVs have been newly considered a part of the metastatic cascade. They have a prominent role in preparing the so-called "tumor niches" in target organs. However, recent evidence has pointed out an even more interesting role of tumor EVs, consisting in their ability to induce malignant transformation in resident mesenchymal stem cells. All in all, in this review, we discuss the multiple involvements of EVs in the metastatic cascade, and how we can exploit and manipulate EVs in order to reduce the metastatic spread of malignant tumors.