Tumor-derived exosomes, microRNAs, and cancer immune suppression

Cancer-associated fibroblasts-secreted exosomal miR-92a-3p promotes tumor growth and stemness in hepatocellular carcinoma through activation of Wnt/β-catenin signaling pathway by suppressing AXIN1

Cancer-associated fibroblasts (CAFs) are a major cellular component in the tumor microenvironment and have been shown to exhibit protumorigenic effects in hepatocellular carcinoma (HCC). This study aimed to delve into the mechanisms underlying the tumor-promoting effects of CAFs in HCC. Small RNA sequencing was conducted to screen differential expressed microRNAs in exosomes derived from CAFs and normal fibroblasts (NFs). The miR-92a-3p expression was then measured using reverse transcriptase quantitative real-time PCR in CAFs, NFs, CAFs-derived exosomes (CAFs-Exo), and NF-derived exosomes (NFs-Exo). Compared to NFs or NF-Exo, CAFs and CAFs-Exo significantly promoted HCC cell proliferation, migration, and stemness. Additionally, compared to NFs or NF-Exo, miR-92a-3p level was notably higher in CAFs and CAFs-Exo, respectively. Exosomal miR-92a-3p was found to enhance HCC cell proliferation, migration, and stemness. Meanwhile, AXIN1 was targeted by miR-92a-3p. Exosomal miR-92a-3p could activate β-catenin/CD44 signaling in HCC cells by inhibiting AXIN1 messenger RNA. Furthermore, in vivo studies verified that exosomal miR-92a-3p notably promoted tumor growth and stemness through targeting AXIN1/β-catenin axis. Collectively, CAFs secreted exosomal miR-92a-3p was capable of promoting growth and stemness in HCC through activation of Wnt/β-catenin signaling pathway by suppressing AXIN1. Therefore, targeting CAFs-derived miR-92a-3p may be a potential strategy for treating HCC.

Immune capture and protein profiling of small extracellular vesicles from human plasma

Extracellular vesicles (EVs), the key players in inter-cellular communication, are produced by all cell types and are present in all body fluids. Analysis of the proteome content is an important approach in structural and functional studies of these vesicles. EVs circulating in human plasma are heterogeneous in size, cellular origin, and functions. This heterogeneity and the potential presence of contamination with plasma components such as lipoprotein particles and soluble plasma proteins represent a challenge in profiling the proteome of EV subsets by mass spectrometry. An immunocapture strategy prior to mass spectrometry may be used to isolate a homogeneous subpopulation of small EVs (sEV) with a specific endocytic origin from plasma or other biofluids. Immunocapture selectively separates EV subpopulations in biofluids based on the presence of a unique protein carried on the vesicle surface. The advantages and disadvantages of EV immune capture as a preparative step for mass spectrometry are discussed.

Theranostic signature of tumor-derived exosomes in cancer

Cancer is the most challenging global health crisis. In the recent times, studies on extracellular vesicles (EVs) are adding a new chapter to cancer research and reports on EVs explores cancer in a new dimension. Exosomes are a group of subpopulations of EVs. It originates from the endosomes and carries biologically active molecules to the neighboring cells which in turn transforms the recipient cell activity. In general, it plays a role in cellular communication. The correlation between exosomes and cancer is fascinating. Tumor-derived exosomes (TEXs) play a dynamic role in cancer progression and are associated with uncontrolled cell growth, angiogenesis, immune suppression, and metastasis. Its molecular cargo is an excellent source of cancer biomarkers. Several advanced molecular profiling approaches assist in exploring the TEXs in depth. This paves the way for a strong foundation for identifying and detecting more specific and efficient biomarkers. TEXs are also gaining importance in scientific society for its role in cancer therapy and several clinical trials based on TEXs is a proof of its significance. In this review, we have highlighted the role of TEXs in mediating immune cell reprogramming, cancer development, metastasis, EMT, organ-specific metastasis, and its clinical significance in cancer theranostics. TEXs profiling is an effective method to understand the complications associated with cancer leading to good health and well-being of the individual and society as a whole.

Acute myeloid leukemia-derived exosomes deliver miR-24-3p to hinder the T-cell immune response through DENN/MADD targeting in the NF-κB signaling pathways

BACKGROUND

microRNAs (miRNAs) are known as potent gene expression regulators, and several studies have revealed the prognostic value of miRNAs in acute myeloid leukemia (AML) patient survival. Recently, strong evidence has indicated that miRNAs can be transported by exosomes (EXOs) from cancer cells to recipient immune microenvironment (IME) cells.

RESULTS

We found that AML blast-released EXOs enhance CD3 T-cell apoptosis in both CD4 and CD8 T cells. We hypothesized that miRNAs present in EXOs are key players in mediating the changes observed in AML T-cell survival. We found that miR-24-3p, a commonly overexpressed miRNA in AML, was present in released EXOs, suggesting that EXO-miR-24-3p was linked to the increased miR-24-3p levels detected in isolated AML T cells. These results were corroborated by ex vivo-generated miR-24-3p-enriched EXOs, which showed that miR-24-3p-EXOs increased apoptosis and miR-24-3p levels in T cells. We also demonstrated that overexpression of miR-24-3p increased T-cell apoptosis and affected T-cell proliferation by directly targeting DENN/MADD expression and indirectly altering the NF-κB, p-JAK/STAT, and p-ERK signaling pathways but promoting regulatory T-cell (Treg) development.

CONCLUSIONS

These results highlight a mechanism through which AML blasts indirectly impede T-cell function via transferred exosomal miR-24-3p. In conclusion, by characterizing the signaling network regulated by individual miRNAs in the leukemic IME, we aimed to discover new nonleukemic immune targets to rescue the potent antitumor function of T cells against AML blasts. Video Abstract.

Gla-domain mediated targeting of externalized phosphatidylserine for intracellular delivery

Phosphatidylserine (PS) is a negatively charged phospholipid normally localized to the inner leaflet of the plasma membrane of cells but is externalized onto the cell surface during apoptosis as well as in malignant and infected cells. Consequently, PS may comprise an important molecular target in diagnostics, imaging, and targeted delivery of therapeutic agents. While an array of PS-binding molecules exist, their utility has been limited by their inability to internalize diagnostic or therapeutic payloads. We describe the generation, isolation, characterization, and utility of a PS-binding motif comprised of a carboxylated glutamic acid (GLA) residue domain that both recognizes and binds cell surface-exposed PS, and then unlike other PS-binding molecules is internalized into these cells. Internalization is independent of the traditional endosomal-lysosomal pathway, directly entering the cytosol of the target cell rapidly. We demonstrate that this PS recognition extends to stem cells and that GLA-domain-conjugated probes can be detected upon intravenous administration in animal models of infectious disease and cancer. GLA domain binding and internalization offer new opportunities for specifically targeting cells with surface-exposed PS for imaging and delivery of therapeutics.

Extracellular vesicles in renal cell carcinoma: challenges and opportunities coexist

Renal cell carcinoma (RCC) represents an extremely challenging disease in terms of both diagnosis and treatment. It poses a significant threat to human health, with incidence rates increasing at a yearly rate of roughly 2%. Extracellular vesicles (EVs) are lipid-based bilayer structures of membranes that are essential for intercellular interaction and have been linked to the advancement of RCC. This review provides an overview of recent studies on the role of EVs in RCC progression, including involvement in the interaction of tumor cells with M2 macrophages, mediating the generation of immune tolerance, and assuming the role of communication messengers in the tumor microenvironment leading to disease progression. Finally, the " troika " of EVs in RCC therapy is presented, including engineered sEVs' or EVs tumor vaccines, mesenchymal stem cell EVs therapy, and reduction of tumor-derived EVs secretion. In this context, we highlight the limitations and challenges of EV-based research and the prospects for future developments in this field. Overall, this review provides a comprehensive summary of the role of EVs in RCC and their potential as a viable pathway for the future treatment of this complex disease.

Role of exosomes in the development of the immune microenvironment in hepatocellular carcinoma

Despite numerous improved treatment methods used in recent years, hepatocellular carcinoma (HCC) is still a disease with a high mortality rate. Many recent studies have shown that immunotherapy has great potential for cancer treatment. Exosomes play a significant role in negatively regulating the immune system in HCC. Understanding how these exosomes play a role in innate and adaptive immunity in HCC can significantly improve the immunotherapeutic effects on HCC. Further, engineered exosomes can deliver different drugs and RNA molecules to regulate the immune microenvironment of HCC by regulating the aforementioned immune pathway, thereby significantly improving the mortality rate of HCC. This study aimed to declare the role of exosomes in the development of the immune microenvironment in HCC and list engineered exosomes that could be used for clinical transformation therapy. These findings might be beneficial for clinical patients.

Neutrophils in Cancer and Potential Therapeutic Strategies Using Neutrophil-Derived Exosomes

Neutrophils are the most abundant immune cells and make up about 70% of white blood cells in human blood and play a critical role as the first line of defense in the innate immune response. They also help regulate the inflammatory environment to promote tissue repair. However, in cancer, neutrophils can be manipulated by tumors to either promote or hinder tumor growth depending on the cytokine pool. Studies have shown that tumor-bearing mice have increased levels of neutrophils in peripheral circulation and that neutrophil-derived exosomes can deliver various cargos, including lncRNA and miRNA, which contribute to tumor growth and degradation of extracellular matrix. Exosomes derived from immune cells generally possess anti-tumor activities and induce tumor-cell apoptosis by delivering cytotoxic proteins, ROS generation, H2O2 or activation of Fas-mediated apoptosis in target cells. Engineered exosome-like nanovesicles have been developed to deliver chemotherapeutic drugs precisely to tumor cells. However, tumor-derived exosomes can aggravate cancer-associated thrombosis through the formation of neutrophil extracellular traps. Despite the advancements in neutrophil-related research, a detailed understanding of tumor-neutrophil crosstalk is still lacking and remains a major barrier in developing neutrophil-based or targeted therapy. This review will focus on the communication pathways between tumors and neutrophils, and the role of neutrophil-derived exosomes (NDEs) in tumor growth. Additionally, potential strategies to manipulate NDEs for therapeutic purposes will be discussed.

Immunopathology of Extracellular Vesicles in Macrophage and Glioma Cross-Talk

Glioblastomas (GBM) are a devastating disease with extremely poor clinical outcomes. Resident (microglia) and infiltrating macrophages are a substantial component of the tumor environment. In GBM and other cancers, tumor-derived extracellular vesicles (EVs) suppress macrophage inflammatory responses, impairing their ability to identify and phagocytose cancerous tissues. Furthermore, these macrophages then begin to produce EVs that support tumor growth and migration. This cross-talk between macrophages/microglia and gliomas is a significant contributor to GBM pathophysiology. Here, we review the mechanisms through which GBM-derived EVs impair macrophage function, how subsequent macrophage-derived EVs support tumor growth, and the current therapeutic approaches to target GBM/macrophage EV crosstalk.

Extracellular Vesicles and Their Roles in the Tumor Immune Microenvironment

Tumor cells actively incorporate molecules (e.g., proteins, lipids, RNA) into particles named extracellular vesicles (EVs). Several groups have demonstrated that EVs can be transferred to target (recipient) cells, making EVs an important means of intercellular communication. Indeed, EVs are able to modulate the functions of target cells by reprogramming signaling pathways. In a cancer context, EVs promote the formation of a supportive tumor microenvironment (TME) and (pre)metastatic niches. Recent studies have revealed that immune cells, tumor cells and their secretome, including EVs, promote changes in the TME and immunosuppressive functions of immune cells (e.g., natural killer, dendritic cells, T and B cells, monocytes, macrophages) that allow tumor cells to establish and propagate. Despite the growing knowledge on EVs and on their roles in cancer and as modulators of the immune response/escape, the translation into clinical practice remains in its early stages, hence requiring improved translational research in the EVs field. Here, we comprehensively review the current knowledge and most recent research on the roles of EVs in tumor immune evasion and immunosuppression in both solid tumors and hematological malignancies. We also highlight the clinical utility of EV-mediated immunosuppression targeting and EV-engineering. Importantly, we discuss the controversial role of EVs in cancer biology, current limitations and future perspectives to further the EV knowledge into clinical practice.

OncomiRs as noncoding RNAs having functions in cancer: Their role in immune suppression and clinical implications

Currently, microRNAs have been established as central players in tumorigenesis, but above all, they have opened an important door for our understanding of immune and tumor cell communication. This dialog is largely due to onco-miR transfer from tumor cells to cells of the tumor microenvironment by exosome. This review outlines recent advances regarding the role of oncomiRs in enhancing cancer and how they modulate the cancer-related immune response in the tumor immune microenvironment.

MicroRNAs (miRNAs) are a type of noncoding RNA that are important posttranscriptional regulators of messenger RNA (mRNA) translation into proteins. By regulating gene expression, miRNAs enhance or inhibit cancer development and participate in several cancer biological processes, including proliferation, invasion metastasis, angiogenesis, chemoresistance and immune escape. Consistent with their widespread effects, miRNAs have been categorized as oncogenes (oncomiRs) or tumor suppressor (TS) miRNAs. MiRNAs that promote tumor growth, called oncomiRs, inhibit messenger RNAs of TS genes and are therefore overexpressed in cancer. In contrast, TS miRNAs inhibit oncogene messenger RNAs and are therefore underexpressed in cancer. Endogenous miRNAs regulate different cellular pathways in all cell types. Therefore, they are not only key modulators in cancer cells but also in the cells constituting their microenvironments. Recently, it was shown that miRNAs are also involved in intercellular communication. Indeed, miRNAs can be transferred from one cell type to another where they regulate targeted gene expression. The primary carriers for the transfer of miRNAs from one cell to another are exosomes. Exosomes are currently considered the primary carriers for communication between the tumor and its surrounding stromal cells to support cancer progression and drive immune suppression. Exosome and miRNAs are seen by many as a hope for developing a new class of targeted therapy. This review outlines recent advances in understanding the role of oncomiRs in enhancing cancer and how they promote its aggressive characteristics and deeply discusses the role of oncomiRs in suppressing the anticancer immune response in its microenvironment. Additionally, further understanding the mechanism of oncomiR-related immune suppression will facilitate the use of miRNAs as biomarkers for impaired antitumor immune function, making them ideal immunotherapy targets.

Glioblastoma Extracellular Vesicle-Specific Peptides Inhibit EV-Induced Neuronal Cytotoxicity

WHO Grade 4 IDH-wild type astrocytoma (GBM) is the deadliest brain tumor with a poor prognosis. Meningioma (MMA) is a more common “benign” central nervous system tumor but with significant recurrence rates. There is an urgent need for brain tumor biomarkers for early diagnosis and effective treatment options. Extracellular vesicles (EVs) are tiny membrane-enclosed vesicles that play essential functions in cell-to-cell communications among tumor cells. We aimed to identify epitopes of brain tumor EVs by phage peptide libraries. EVs from GBM plasma, MMA plasma, or brain tumor cell lines were used to screen phage-displayed random peptide libraries to identify high-affinity peptides. We purified EVs from three GBM plasma pools (23 patients), one MMA pool (10 patients), and four brain tumor cell lines. We identified a total of 21 high-affinity phage peptides (12 unique) specific to brain tumor EVs. The peptides shared high sequence homologies among those selected by the same EVs. Dose–response ELISA demonstrated that phage peptides were specific to brain tumor EVs compared to controls. Peptide affinity purification identified unique brain tumor EV subpopulations. Significantly, GBM EV peptides inhibit brain tumor EV-induced complement-dependent cytotoxicity (necrosis) in neurons. We conclude that phage display technology could identify specific peptides to isolate and characterize tumor EVs.

Exosomal PD-L1 predicts response with immunotherapy in NSCLC patients

Immune Check-Point Inhibitors (ICIs) have shown remarkable promise in treating tumors, including non-small cell lung cancer (NSCLC). Nevertheless, the treatment response rate is low. Studies have found that the high expression of exosomal PD-L1 is one of the reasons for the low treatment response. Therefore, this study focused on the relationship between the exosomal PD-L1 and the clinical response to immunotherapy in NSCLC patients to evaluate whether it could be used as a biomarker to predict the efficacy of ICIs. In this study, clinical information and blood samples of 149 NSCLC patients receiving ICIs were collected. The expression level of exosomal PD-L1 was detected by enzyme-linked immunosorbent assay method, and the relationship between exosomal PD-L1 and the efficacy of ICIs was explored. Overall, our study found that the expression level of exosomal PD-L1 was lower at pre-treatment, or the max fold increasing change higher at 3-6 weeks had a higher disease control rate and longer progression-free survival. It revealed that the exosomal PD-L1 was associated with the treatment response of patients using ICIs and provided a new tool for the evaluation of clinical efficacy of lung cancer immunotherapy.

Extracellular Vesicle-Mediated Mitochondrial Reprogramming in Cancer

Simple Summary

Mitochondria are important organelles involved in several key cellular processes including energy production and cell death regulation. For this reason, it is unsurprising that mitochondrial function and structure are altered in several pathological states including cancer. Cancer cells present variate strategies to generate sufficient energy to sustain their high proliferation rates. These adaptative strategies can be mediated by extracellular signals such as extracellular vesicles. These vesicles can alter recipient cellular behavior by delivering their molecular cargo. This review explores the different EV-mediated mitochondrial reprogramming mechanisms supporting cancer survival and progression.

Abstract

Altered metabolism is a defining hallmark of cancer. Metabolic adaptations are often linked to a reprogramming of the mitochondria due to the importance of these organelles in energy production and biosynthesis. Cancer cells present heterogeneous metabolic phenotypes that can be modulated by signals originating from the tumor microenvironment. Extracellular vesicles (EVs) are recognized as key players in intercellular communications and mediate many of the hallmarks of cancer via the delivery of their diverse biological cargo molecules. Firstly, this review introduces the most characteristic changes that the EV-biogenesis machinery and mitochondria undergo in the context of cancer. Then, it focuses on the EV-driven processes which alter mitochondrial structure, composition, and function to provide a survival advantage to cancer cells in the context of the hallmarks of cancers, such as altered metabolic strategies, migration and invasiveness, immune surveillance escape, and evasion of apoptosis. Finally, it explores the as yet untapped potential of targeting mitochondria using EVs as delivery vectors as a promising cancer therapeutic strategy.

Tumor-derived exosomal microRNA-15b-5p augments laryngeal cancer by targeting TXNIP

Tumor-derived exosomes (EXO) are information carriers of microRNA (miR) in cancer development. Here, we explored the synergism of tumor-derived EXO and miR-15b-5p in laryngeal cancer (LCa). miR-15b-5p and thioredoxin-interacting protein (TXNIP) levels were firstly measured in clinical LCa tissues. The association between miR-15b-5p and TXNIP was determined. miR-15b-5p mimic was transfected into HEP-2 cells, and the corresponding exosomes were extracted. miR-15b-5p mimic-modified EXO were co-cultured with HEP-2 cells, and TXNIP low expression/high expression vector was transfected into HEP-2 cells Finally, cell growth was observed in vitro and in vivo. miR-15b-5p level was high while TXNIP level was low in LCa, and miR-15b-5p negatively modulated TXNIP expression. HEP-2 cells-derived EXO or inhibition of TXNIP enhanced HEP-2 cell growth in vitro and in vivo. Up-regulated miR-15b-5p further strengthened the pro-tumor effect of EXO, but this effect was reversed by overexpression of TXNIP. Overall, tumor-derived exosomal miR-15b-5p augments LCa through targeting down-regulation of TXNIP.

Tumor-Derived Exosomes in Tumor-Induced Immune Suppression

Exosomes are a class of small membrane-bound extracellular vesicles released by almost all cell types and present in all body fluids. Based on the studies of exosome content and their interactions with recipient cells, exosomes are now thought to mediate “targeted” information transfer. Tumor-derived exosomes (TEX) carry a cargo of molecules different from that of normal cell-derived exosomes. TEX functions to mediate distinct biological effects such as receptor discharge and intercellular cross-talk. The immune system defenses, which may initially restrict tumor progression, are progressively blunted by the broad array of TEX molecules that activate suppressive pathways in different immune cells. Herein, we provide a review of the latest research progress on TEX in the context of tumor-mediated immune suppression and discuss the potential as well as challenges of TEX as a target of immunotherapy.

Simultaneous disruption of circulating miR-21 and cytotoxic T lymphocytes (CTLs): Prospective diagnostic and prognostic markers for esophageal squamous cell carcinoma (ESCC)

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) as the most prominent type of esophageal cancer (EC) in developing countries encompasses a substantial contribution of cancer-related mortalities and morbidities. Cytotoxic T lymphocytes (CTLs) are the major subset of effector T cells against cancer. However, the microRNAs involved in the development and regulation of CTLs could be disrupted in cancers such as EC.

METHODS

Here, we evaluated the population of IL-10, TGF-β, IFN-γ, and IL-17a-producing CD3+CD8+ T cells, their association with the circulating levels of miR-21 and miR-29b, and their diagnostic and/or prognostic (after 160 weeks of follow-up) utilities in 34 ESCC patients (12 newly diagnosed: ND, 24 under-treatment: UT) and 34 matched healthy donors.

RESULTS

The population of IL-10 and TGF-β-producing CTLs (CD8+ Tregs) were considerably expanded, in addition to the overexpression of miR-21 in both groups (ND and UT) of ESCC patients, while the frequency of Tc17 and CD8+ Treg cells increased only in UT patients. The expression means of TGF-β and IL-10 in CTLs were considered to be excellent biomarkers (1 ≥ area under the curve: AUC ≥0.9) in distinguishing ESCC patients and associated subgroups from healthy subjects. Moreover, the lower expressions of TGF-β, IL-17a, IL-10, and IFN-γ in CTLs were associated with ESCC better prognosis.

CONCLUSIONS

The association between the impaired function of CD3+ CD8+ T cell subsets and miR-21 expression could be introduced as novel therapeutic targets and powerful diagnostic and prognostic markers for ESCC.

Cancer associated-fibroblast-derived exosomes in cancer progression

To identify novel cancer therapies, the tumor microenvironment (TME) has received a lot of attention in recent years in particular with the advent of clinical successes achieved by targeting immune checkpoint inhibitors (ICIs). The TME consists of multiple cell types that are embedded in the extracellular matrix (ECM), including immune cells, endothelial cells and cancer associated fibroblasts (CAFs), which communicate with cancer cells and each other during tumor progression. CAFs are a dominant and heterogeneous cell type within the TME with a pivotal role in controlling cancer cell invasion and metastasis, immune evasion, angiogenesis and chemotherapy resistance. CAFs mediate their effects in part by remodeling the ECM and by secreting soluble factors and extracellular vesicles. Exosomes are a subtype of extracellular vesicles (EVs), which contain various biomolecules such as nucleic acids, lipids, and proteins. The biomolecules in exosomes can be transmitted from one to another cell, and thereby affect the behavior of the receiving cell. As exosomes are also present in circulation, their contents can also be explored as biomarkers for the diagnosis and prognosis of cancer patients. In this review, we concentrate on the role of CAFs-derived exosomes in the communication between CAFs and cancer cells and other cells of the TME. First, we introduce the multiple roles of CAFs in tumorigenesis. Thereafter, we discuss the ways CAFs communicate with cancer cells and interplay with other cells of the TME, and focus in particular on the role of exosomes. Then, we elaborate on the mechanisms by which CAFs-derived exosomes contribute to cancer progression, as well as and the clinical impact of exosomes. We conclude by discussing aspects of exosomes that deserve further investigation, including emerging insights into making treatment with immune checkpoint inhibitor blockade more efficient.

Molecular Mediators of RNA Loading into Extracellular Vesicles

In the last decade, an increasing number of studies have demonstrated that non-coding RNA (ncRNAs) cooperate in the gene regulatory networks with other biomolecules, including coding RNAs, DNAs and proteins. Among them, microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) are involved in transcriptional and translation regulation at different levels. Intriguingly, ncRNAs can be packed in vesicles, released in the extracellular space, and finally internalized by receiving cells, thus affecting gene expression also at distance. This review focuses on the mechanisms through which the ncRNAs can be selectively packaged into extracellular vesicles (EVs).

Exosomes: A Forthcoming Era of Breast Cancer Therapeutics

Despite the recent advancements in therapeutics and personalized medicine, breast cancer remains one of the most lethal cancers among women. The prognostic and diagnostic aids mainly include assessment of tumor tissues with conventional methods towards better therapeutic strategies. However, current era of gene-based research may influence the treatment outcome particularly as an adjunct to diagnostics by exploring the role of non-invasive liquid biopsies or circulating markers. The characterization of tumor milieu for physiological fluids has been central to identifying the role of exosomes or small extracellular vesicles (sEVs). These exosomes provide necessary communication between tumor cells in the tumor microenvironment (TME). The manipulation of exosomes in TME may provide promising diagnostic/therapeutic strategies, particularly in triple-negative breast cancer patients. This review has described and highlighted the role of exosomes in breast carcinogenesis and how they could be used or targeted by recent immunotherapeutics to achieve promising intervention strategies.

Cytokine-Laden Extracellular Vesicles Predict Patient Prognosis after Cerebrovascular Accident

Background: A major contributor to disability after hemorrhagic stroke is secondary brain damage induced by the inflammatory response. Following stroke, global increases in numerous cytokines—many associated with worse outcomes—occur within the brain, cerebrospinal fluid, and peripheral blood. Extracellular vesicles (EVs) may traffic inflammatory cytokines from damaged tissue within the brain, as well as peripheral sources, across the blood–brain barrier, and they may be a critical component of post-stroke neuroinflammatory signaling. Methods: We performed a comprehensive analysis of cytokine concentrations bound to plasma EV surfaces and/or sequestered within the vesicles themselves. These concentrations were correlated to patient acute neurological condition by the Glasgow Coma Scale (GCS) and to chronic, long-term outcome via the Glasgow Outcome Scale-Extended (GOS-E). Results: Pro-inflammatory cytokines detected from plasma EVs were correlated to worse outcomes in hemorrhagic stroke patients. Anti-inflammatory cytokines detected within EVs were still correlated to poor outcomes despite their putative neuroprotective properties. Inflammatory cytokines macrophage-derived chemokine (MDC/CCL2), colony stimulating factor 1 (CSF1), interleukin 7 (IL7), and monokine induced by gamma interferon (MIG/CXCL9) were significantly correlated to both negative GCS and GOS-E when bound to plasma EV membranes. Conclusions: These findings correlate plasma-derived EV cytokine content with detrimental outcomes after stroke, highlighting the potential for EVs to provide cytokines with a means of long-range delivery of inflammatory signals that perpetuate neuroinflammation after stroke, thus hindering recovery.

Tumor-Associated Macrophages as Multifaceted Regulators of Breast Tumor Growth

Breast cancer is the most commonly occurring cancer in women of Western countries and is the leading cause of cancer-related mortality. The breast tumor microenvironment contains immune cells, fibroblasts, adipocytes, mesenchymal stem cells, and extracellular matrix. Among these cells, macrophages or tumor-associated macrophages (TAMs) are the major components of the breast cancer microenvironment. TAMs facilitate metastasis of the breast tumor and are responsible for poor clinical outcomes. High TAM density was also found liable for the poor prognosis of breast cancer. These observations make altering TAM function a potential therapeutic target to treat breast cancer. The present review summarizes the origin of TAMs, mechanisms of macrophage recruitment and polarization in the tumor, and the contributions of TAMs in tumor progression. We have also discussed our current knowledge about TAM-targeted therapies and the roles of miRNAs and exosomes in re-educating TAM function.

Tumor-Derived Exosomes (TEX) and Their Role in Immuno-Oncology

Extracellular vesicles (EVs) play a key role in health and disease, including cancer. Tumors produce a mix of EVs differing in size, cellular origin, biogenesis and molecular content. Small EVs (sEV) or exosomes are a subset of 30-150 nm (virus-size) vesicles originating from the multivesicular bodies (MVBs) and carrying a cargo that in its content and topography approximates that of a parent cell. Tumor-derived exosomes (TEX) present in all body fluids of cancer patients, are considered promising candidates for a liquid tumor biopsy. TEX also mediate immunoregulatory activities: they maintain a crosstalk between the tumor and various non-malignant cells, including immunocytes. Effects that EVs exert on immune cells may be immunosuppressive or immunostimulatory. Here, we review the available data for TEX interactions with immunocytes, focusing on strategies that allow isolation from plasma and separation of TEX from sEV produced by non-malignant cells. Immune effects mediated by either of the subsets can now be distinguished and measured. The approach has allowed for the comparison of molecular and functional profiles of the two sEV fractions in plasma of cancer patients. While TEX carried an excess of immunosuppressive proteins and inhibited immune cell functions in vitro and in vivo, the sEV derived from non-malignant cells, including CD3(+)T cells, were variably enriched in immunostimulatory proteins and could promote functions of immunocytes. Thus, sEV in plasma of cancer patients are heterogenous, representing a complex molecular network which is not evident in healthy donors' plasma. Importantly, TEX appear to be able to reprogram functions of non-malignant CD3(+)T cells inducing them to produce CD3(+)sEV enriched in immunosuppressive proteins. Ratios of stimulatory/inhibitory proteins carried by TEX and by CD3(+)sEV derived from reprogrammed non-malignant cells vary broadly in patients and appear to negatively correlate with disease progression. Simultaneous capture from plasma and functional/molecular profiling of TEX and the CD3(+)sEV fractions allows for defining their role as cancer biomarkers and as monitors of cancer patients' immune competence, respectively.

Delivery of miR-224-5p by Exosomes from Cancer-Associated Fibroblasts Potentiates Progression of Clear Cell Renal Cell Carcinoma

Objectives

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal cell carcinoma. Cancer-associated fibroblasts (CAFs) as the primary components of cancer stroma can affect tumor progression by secreting exosomes, while exosomes are carriers for proteins, nucleic acids, and other agents that responsible for delivery of biological information. Given this, exosomes derived from CAFs are emerging as promising biomarkers in clinical cancer diagnosis. Nevertheless, their role in clear cell renal cell carcinoma (ccRCC) remains poorly understood.

Methods

Here, we separated fibroblasts from ccRCC tissue, extracted exosomes, observed their morphology, and detected the expression of exosome marker proteins including Hsp70, CD9, and CD63. In the meantime, we labeled exosomes and performed coculture experiment to verify the delivery of miR-224-5p from CAFs to 769-P cells with exosomes as a carrier, so as to clarify the effect of CAF-derived exosomes on ccRCC cell malignant behaviors, as well as to discuss how miR-224-5p involves in above regulation.

Results

Transmission electron microscopy was firstly applied, and it was noted that the exosomes we isolated were in normal range. Besides, Western blot also confirmed the presence of exosome marker proteins Hsp70, CD9, and CD63. Furthermore, coculture experiments were performed and the CAF-derived exosomes were observed to be able to facilitate the malignant behaviors of ccRCC cells, and the exosomal miR-224-5p could be internalized by ccRCC cells to participate in regulation of cell proliferation, migration, invasion, and apoptosis.

Conclusion

To sum up, miR-224-5p can enter ccRCC cells via CAF-derived exosomes, in turn, promoting the malignant behaviors of ccRCC cells, which indicates that miR-224-5p has the potential severing as a therapeutic target for ccRCC.

Physiological Fitness and the Pathophysiology of Chronic Lymphocytic Leukemia (CLL)

Chronic lymphocytic leukemia (CLL) is associated with physical dysfunction and low overall fitness that predicts poor survival following the commencement of treatment. However, it remains unknown whether higher fitness provides antioncogenic effects. We identified ten fit (CLL-FIT) and ten less fit (CLL-UNFIT) treatment-naïve CLL patients from 144 patients who completed a set of physical fitness and performance tests. Patient plasma was used to determine its effects on an in vitro 5-day growth/viability of three B-cell cell lines (OSU-CLL, Daudi, and Farage). Plasma exosomal miRNA profiles, circulating lipids, lipoproteins, inflammation levels, and immune cell phenotypes were also assessed. CLL-FIT was associated with fewer viable OSU-CLL cells at Day 1 (p = 0.003), Day 4 (p = 0.001), and Day 5 (p = 0.009). No differences between the groups were observed for Daudi and Farage cells. Of 455 distinct exosomal miRNAs identified, 32 miRNAs were significantly different between the groups. Of these, 14 miRNAs had ≤-1 or ≥1 log2 fold differences. CLL-FIT patients had five exosomal miRNAs with lower expression and nine miRNAs with higher expression. CLL-FIT patients had higher HDL cholesterol, lower inflammation, and lower levels of triglyceride components (all p < 0.05). CLL-FIT patients had lower frequencies of low-differentiated NKG2+/CD158a/b^neg (p = 0.015 and p = 0.014) and higher frequencies of NKG2A^neg/CD158b+ mature NK cells (p = 0.047). The absolute number of lymphocytes, including CD19+/CD5+ CLL-cells, was similar between the groups (p = 0.359). Higher physical fitness in CLL patients is associated with altered CLL-like cell line growth in vitro and with altered circulating and cellular factors indicative of better immune functions and tumor control.

Exosomes derived from hypoxic glioma deliver miR-1246 and miR-10b-5p to normoxic glioma cells to promote migration and invasion

Hypoxia is an important feature of the tumor microenvironment and is associated with glioma progression and patient outcome. Exosomes have been implicated in the intercellular communication in the tumor microenvironment. However, the effects of hypoxic glioma exosomes on glioma migration and invasion and the underlying mechanisms remain poorly understood. In this study, we found that exosomes derived from hypoxic glioma cells (H-GDEs) promoted normoxic glioma migration and invasion in vitro and in vivo. Given that exosomes can regulate recipient cell functions by delivering microRNAs, we further revealed miR-1246 and miR-10b-5p were upregulated significantly in H-GDEs and delivered to normoxic glioma cells by H-GDEs. Moreover, we determined the clinical relevance of miR-1246 and miR-10b-5p in glioma patients. Subsequent investigations indicated that miR-1246 and miR-10b-5p markedly induced glioma migration and invasion in vitro and in vivo. Finally, we demonstrated that miR-1246 and miR-10b-5p induced glioma migration and invasion by directly targeting FRK and TFAP2A respectively. In conclusion, our findings suggest that the hypoxic microenvironment stimulates glioma to generate miR-1246- and miR-10b-5p-rich exosomes that are delivered to normoxic glioma cells to promote their migration and invasion; treatment targeting miR-1246 and miR-10b-5p may impair the motility of gliomas, providing a novel direction for the development of antitumor therapy.

Exosomal MicroRNAs Mediating Crosstalk Between Cancer Cells With Cancer-Associated Fibroblasts and Tumor-Associated Macrophages in the Tumor Microenvironment

Exosomes are small extracellular vesicles containing diverse bioactive molecules. They play essential roles in mediating bidirectional interplay between cancer and stromal cells. Specific elements are selected into different types of exosomes via various mechanisms, including microRNAs (miRNAs), a subset of non-coding RNA that could epigenetically reprogram cells and modulate their activities. Cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs) are two major types of stromal cells inhibiting immune response and facilitating tumor progression. Notably, accumulated studies provided critical evidence regarding the significance of exosomal miRNA–mediated intercellular crosstalk between cancer cells with TAMs and CAFs for tumor progression. This review aimed to summarize the current knowledge of cell–cell interactions between stromal and cancer cells conveyed by exosome-derived miRNAs. The findings might help find effective therapeutic targets of cancer.

Exosomal miR-222 from adriamycin-resistant MCF-7 breast cancer cells promote macrophages M2 polarization via PTEN/Akt to induce tumor progression

Exosome-mediated intercellular communication is considered to be an effective mode for malignant cells to transform biological behaviors in stromal cells. However, the mechanisms by which exosomes modulate macrophages within tumor microenvironment remain largely unclear. In this study, we found that both adriamycin-resistant breast cancer (BCa) cells and the corresponding exosomes (A/exo) were capable of inducing macrophages M2 polarization, which promoted the mobility, proliferation, migration and invasion of BCa cells. Since exosomes deliver microRNAs to affect cellular functions in recipient cells, we confirmed that miR-222 was significantly enriched in A/exo and could be successfully transferred to macrophages. Increased miR-222 level was also detected in exosomes derived from plasma and tissues of chemoresistant patients. Moreover, exosomal miR-222 from A/exo polarized M2 macrophages by targeting PTEN and activating Akt signaling pathway, which promoted BCa cells progression in a feed back loop. Co-culture of adriamycin-resistant BCa cells with macrophages in which miR-222 was upregulated or treated with A/exo facilitated tumor growth in vivo. Collectively, our data demonstrated that chemoresistant BCa cells could remodel macrophages within tumor microenvironment by secreting exosomal miR-222, which directly targeted PTEN and caused Akt cascade activation and macrophages M2 polarization. Our findings may provide a foundation for a promising strategy of BCa treatment by targeting exosomes or exosomal miR-222.

Exosomes in osteosarcoma research and preclinical practice

Osteosarcoma (OS) is a rare soft-tissue malignant tumor with high lung metastasis and mortality rates. Preoperative chemotherapy, surgical resection of the lesion and postoperative chemotherapy are still the main treatments for osteosarcoma. The prognosis, however, is poor for patients with nonresectable, primary metastatic or relapsed disease. Recent studies have shown that targeted therapy for OS based on the characteristics of exosomes is very attractive. Exosomes are nanosized extracellular vesicles (EVs) that participate in cell-to-cell communication by transporting biologically active cargo molecules, causing changes in OS cell function and playing important roles in OS disease progression. With the characteristics of secretory cells, exosomes transport cargo (e.g., microRNAs) that can be used to detect the progress of a disease and can serve as markers and/or therapeutic targets for clinical diagnosis of OS. In this review, the roles of exosomes in OS pathogenesis, invasion, metastasis, drug resistance, diagnosis and treatment are summarized. In addition, this article elaborates a series of challenges to overcome before exosomes are applied in clinical practice and provides suggestions based on current evidence for the direction of future research.

The key roles of cancer stem cell-derived extracellular vesicles

Cancer stem cells (CSCs), the subpopulation of cancer cells, have the capability of proliferation, self-renewal, and differentiation. The presence of CSCs is a key factor leading to tumor progression and metastasis. Extracellular vesicles (EVs) are nano-sized particles released by different kinds of cells and have the capacity to deliver certain cargoes, such as nucleic acids, proteins, and lipids, which have been recognized as a vital mediator in cell-to-cell communication. Recently, more and more studies have reported that EVs shed by CSCs make a significant contribution to tumor progression. CSCs-derived EVs are involved in tumor resistance, metastasis, angiogenesis, as well as the maintenance of stemness phenotype and tumor immunosuppression microenvironment. Here, we summarized the molecular mechanism by which CSCs-derived EVs in tumor progression. We believed that the fully understanding of the roles of CSCs-derived EVs in tumor development will definitely provide new ideas for CSCs-based therapeutic strategies.

Extracellular Vesicle (EV) biohybrid systems for cancer therapy: Recent advances and future perspectives

Extracellular vesicles (EVs) are a class of cell-derived lipid-bilayer membrane vesicles secreted by almost all mammalian cells and involved in intercellular communication by shuttling various biological cargoes. Over the last decade, EVs - namely exosomes and microvesicles - have been extensively explored as next-generation nanoscale drug delivery systems (DDSs). This is in large due to their endogenous origin, which enables EVs to circumvent some of the limitations associated with existing cancer therapy approaches (i.e. by preventing recognition by the immune system and improving selectivity towards tumor tissue). However, successful translation of these cell-derived vesicles into clinical applications has been hindered by several factors, among which the loading of exogenous therapeutic molecules still represents a great challenge. In order to address this issue and to further advance these biologically-derived systems as drug carriers, EV-biohybrid nano-DDSs, obtained through the fusion of EVs with conventional synthetic nano-DDSs, have recently been proposed as a valuable alternative as DDSs. Building on the idea of "combining the best of both worlds", a combination of these two unique entities aims to harness the beneficial properties associated with both EVs and conventional nano-DDSs, while overcoming the flaws of the individual components. These biohybrid systems also provide a unique opportunity for exploitation of new synergisms, often leading to improved therapeutic outcomes, thus paving the way for advancements in cancer therapy. This review aims to describe the recent developments of EV-biohybrid nano-DDSs in cancer therapy, to highlight the most promising results and breakthroughs, as well as to provide a glimpse on the possible intrinsic targeting mechanisms of EVs that can be bequeathed to their hybrid systems. Finally, we also provide some insights in the future perspectives of EV-hybrid DDSs.

Exosomes and Cell Communication: From Tumour-Derived Exosomes and Their Role in Tumour Progression to the Use of Exosomal Cargo for Cancer Treatment

Simple Summary

Recently, within the research community, exosomes, transporters of bioactive molecules involved in many signalling pathways and cell-to-cell communication with the capacity to alter the tumour microenvironment, have been attracting increasing interest among oncologists. These molecules can play multiple roles, e.g., as useful biomarkers in diagnosis, modulators of the immune system, promoters of the formation of the pre-metastatic niches and cancer metastasis and carriers of substances or factors with anticancer properties. This review focuses on the use of exosomes as a novel therapeutic strategy for cancer treatment. Particularly, it highlights the potential of exosomes as carriers of stem cell differentiation stage factors (SCDSFs) for “cell reprogramming” therapy, a promising research field on which we have reported previously. Here, the main characteristics of this treatment and the advantages that can be obtained using mesenchymal stem cell-derived exosomes up-loaded with the SCDSFs as carriers of these factors are also discussed.

Abstract

Exosomes are nano-vesicle-shaped particles secreted by various cells, including cancer cells. Recently, the interest in exosomes among cancer researchers has grown enormously for their many potential roles, and many studies have focused on the bioactive molecules that they export as exosomal cargo. These molecules can function as biomarkers in diagnosis or play a relevant role in modulating the immune system and in promoting apoptosis, cancer development and progression. Others, considering exosomes potentially helpful for cancer treatment, have started to investigate them in experimental therapeutic trials. In this review, first, the biogenesis of exosomes and their main characteristics was briefly described. Then, the capability of tumour-derived exosomes and oncosomes in tumour microenvironments (TMEs) remodelling and pre-metastatic niche formation, as well as their interference with the immune system during cancer development, was examined. Finally, the potential role of exosomes for cancer therapy was discussed. Particularly, in addition, their use as carriers of natural substances and drugs with anticancer properties or carriers of boron neutron capture therapy (BNCT) and anticancer vaccines for immunotherapy, exosomes as biological reprogrammers of cancer cells have gained increased consensus. The principal aspects and the rationale of this intriguing therapeutic proposal are briefly considered.

Combined cancer therapeutics-Tackling the complexity of the tumor microenvironment

Cancer treatment has yet to find a "silver bullet" capable of selectively and effectively kill tumor cells without damaging healthy cells. Nanomedicine is a promising field that can combine several moieties in one system to produce a multifaceted nanoplatform. The tumor microenvironment (TME) is considered responsible for the ineffectiveness of cancer therapeutics and the difficulty in the translation from the bench to bed side of novel nanomedicines. A promising approach is the use of combinatorial therapies targeting the TME with the use of stimuli-responsive nanomaterials which would increase tumor targeting. Contemporary combined strategies for TME-targeting nanoformulations are based on the application of external stimuli therapies, such as photothermy, hyperthermia or ultrasounds, in combination with stimuli-responsive nanoparticles containing a core, usually composed by metal oxides or graphene, and a biocompatible stimuli-responsive coating layer that could also contain tumor targeting moieties and a chemotherapeutic agent to enhance the therapeutic efficacy. The obstacles that nanotherapeutics must overcome in the TME to accomplish an effective therapeutic cargo delivery and the proposed strategies for improved nanotherapeutics will be reviewed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies.

MiR-181 Family Modulates Osteopontin in Glioblastoma Multiforme

Simple Summary

MicroRNAs can silence a broad set of target genes that may benefit heterogeneous tumors like glioblastoma. We have previously shown that osteopontin has an oncogenic role and may have immune modulatory effects on macrophages. In the current study, we used miRNAs to target osteopontin in tumor cells and modulate immune cells to elicit an antitumor effect. Intravenous delivery of miR-181a to immune competent mice bearing intracranial glioblastoma demonstrated a 22% increase in median survival duration relative to that of control mice. The overexpression of miR-181a in tumor cells led to decreased OPN production and proliferation and increased apoptosis in vitro, and increased survival duration of the mice when compared to its controls. miR-181a controls osteopontin expression in tumor cells by regulating their proliferation and apoptosis.

Abstract

MiRNAs can silence a wide range of genes, which may be an advantage for targeting heterogenous tumors like glioblastoma. Osteopontin (OPN) plays both an oncogenic role in a variety of cancers and can immune modulate macrophages. We conducted a genome wide profiling and bioinformatic analysis to identify miR-181a/b/c/d as potential miRNAs that target OPN. Luciferase assays confirmed the binding potential of miRNAs to OPN. Expression levels of miR-181a/b/c/d and OPN were evaluated by using quantitative real-time PCR and enzyme-linked immunosorbent assay in mouse and human glioblastomas and macrophages that showed these miRNAs were downregulated in Glioblastoma associated CD11b+ cells compared to their matched blood CD14b+ cells. miRNA mimicking and overexpression using lentiviruses showed that MiR-181a overexpression in glioblastoma cells led to decreased OPN production and proliferation and increased apoptosis in vitro. MiR-181a treatment of immune competent mice bearing intracranial glioblastoma demonstrated a 22% increase in median survival duration relative to that of control mice.

Emerging Role of Extracellular Vesicles in Immune Regulation and Cancer Progression

Simple Summary

Accumulating evidence has reported that extracellular vesicles secreted by different tumor microenvironment cells can interfere with the host immune system. These vesicles transmit the signals in the tumor microenvironment that affect the proliferation, apoptosis, activation, and, metabolism of immune cells such as dendritic cells, T cells, macrophages, and natural killer cells, creating a pro-tumoral environment for tumor progression and survival. In this review, we summarize the recent literature on the function of extracellular vesicles derived from tumor cells and immune cells in regulating the critical processes associated with cancer progression. Besides, we also provide insights on how the extracellular vesicles are employed as diagnostic and prognostic biomarkers and drug carriers in cancer.

Abstract

The development of effective therapies for cancer treatment requires a better understanding of the tumor extracellular environment and a dynamic interaction between tumor cells, the cells of the immune system, and the tumor stroma. Increasing evidence suggests that extracellular vesicles play an important role in this interaction. Extracellular vesicles are nanometer-sized membrane-bound vesicles secreted by various types of cells that facilitate intracellular communication by transferring proteins, various lipids, and nucleic acids, especially miRNAs, between cells. Extracellular vesicles play discrete roles in the immune regulatory functions, such as antigen presentation, and activation or suppression of immune cells. Achieving therapeutic intervention through targeting of extracellular vesicles is a crucial area of research now. Thus, a deeper knowledge of exosome biology and the molecular mechanism of immune regulation is likely to provide significant insight into therapeutic intervention utilizing extracellular vesicles to combat this dreadful disease. This review describes the recent updates on immune regulation by extracellular vesicles in cancer progression and possible use in cancer therapy.

mRNA and miRNA Profiles of Exosomes from Cultured Tumor Cells Reveal Biomarkers Specific for HPV16-Positive and HPV16-Negative Head and Neck Cancer

Human papillomavirus (HPV)(+) and HPV(-) head and neck cancer (HNC) cells' interactions with the host immune system are poorly understood. Recently, we identified molecular and functional differences in exosomes produced by HPV(+) vs. HPV(-) cells, suggesting that genetic cargos of exosomes might identify novel biomarkers in HPV-related HNCs. Exosomes were isolated by size exclusion chromatography from supernatants of three HPV(+) and two HPV(-) HNC cell lines. Paired cell lysates and exosomes were analyzed for messenger RNA (mRNA) by qRT-PCR and microRNA (miR) contents by nanostring analysis. The mRNA profiles of HPV(+) vs. HPV(-) cells were distinct, with EGFR, TP53 and HSPA1A/B overexpressed in HPV(+) cells and IL6, FAS and DPP4 in HPV(-) cells. The mRNA profiles of HPV(+) or HPV(-) exosomes resembled the cargo of their parent cells. miR expression profiles in cell lysates identified 8 miRs expressed in HPV(-) cells vs. 14 miRs in HPV(+) cells. miR-205-5p was exclusively expressed in HPV(+) exosomes, and miR-1972 was only detected in HPV(-) exosomes. We showed that HPV(+) and HPV(-) exosomes recapitulated the mRNA expression profiles of their parent cells. Expression of miRs was dependent on the HPV status, and miR-205-5p in HPV(+) and miR-1972 in HPV(-) exosomes emerge as potential discriminating HPV-associated biomarkers.

Binding of RNA Aptamers to Membrane Lipid Rafts: Implications for Exosomal miRNAs Transfer from Cancer to Immune Cells

Intraluminal vesicles (ILVs) are released into the extracellular space as exosomes after the fusion of multivesicular bodies (MVBs) with the plasma membrane. miRNAs are delivered to the raft-like region of MVB by RNA-binding proteins (RBPs). RNA loading into exosomes can be either through direct interaction between RNA and the raft-like region of the MVB membrane, or through interaction between an RBP–RNA complex with this raft-like region. Selection of RNA aptamers that bind to lipid raft region of liposomal membranes was performed using the selection-amplification (SELEX) method. The pool of RNA aptamers was isolated, and the binding of this pool to lipid-raft regions was demonstrated. Sequencing of clones from rafted liposome-eluted RNAs showed sequences apparently of independent origin. Bioinformatics analysis revealed the most frequent raft-motifs present within these sequences. Four raft RNA motifs, one of them an EXO motif, have been identified. These motifs appear to be most frequent both in the case of raft RNA aptamers and in the case of exosomal pro-tumoral miRNAs transferred from cancer cells to macrophages, natural killer cells and dendritic cells, thus suggesting that the selection for incorporation of these miRNAs into ILVs is based on their affinity to the raft-like region of the MVB membrane.

Tiny Actors in the Big Cellular World: Extracellular Vesicles Playing Critical Roles in Cancer

Communications among cells can be achieved either via direct interactions or via secretion of soluble factors. The emergence of extracellular vesicles (EVs) as entities that play key roles in cell-to-cell communication offer opportunities in exploring their features for use in therapeutics; i.e., management and treatment of various pathologies, such as those used for cancer. The potential use of EVs as therapeutic agents is attributed not only for their cell membrane-bound components, but also for their cargos, mostly bioactive molecules, wherein the former regulate interactions with a recipient cell while the latter trigger cellular functions/molecular mechanisms of a recipient cell. In this article, we highlight the involvement of EVs in hallmarks of a cancer cell, particularly focusing on those molecular processes that are influenced by EV cargos. Moreover, we explored the roles of RNA species and proteins carried by EVs in eliciting drug resistance phenotypes. Interestingly, engineered EVs have been investigated and proposed as therapeutic agents in various in vivo and in vitro studies, as well as in several clinical trials.

Anticancer effects of miR-124 delivered by BM-MSC derived exosomes on cell proliferation, epithelial mesenchymal transition, and chemotherapy sensitivity of pancreatic cancer cells

OBJECTIVE

This study aims to explore the roles of miR-124 in pancreatic tumor and potential vehicles.

RESULTS

The miR-124 expression levels decreased in pancreatic adenocarcinoma tissues and cancer cell lines AsPC-1, PANC1, BxPC-3 and SW1990. Furthermore, the elevated expression of miR-124 in AsPC-1 and PANC1 via miR-124 mimic transfection-induced apoptosis, metastasis and epithelial mesenchymal transition was suppressed, and the EZH2 overexpression partly reversed the protective effects of miR-124 against pancreatic tumors. In addition, the expression of miR-124 was detected in exosomes extracted from miR-124-transfected BM-MSCs, and these exosomes delivered miR-124 into pancreatic cancer cells, and presented the anti-tumor effects in vitro and in vivo.

CONCLUSION

MiR-124-carried BM-MSC-derived exosomes have potential applications for the treatment of pancreatic tumors.

METHODS

The expression of miR-124 and EZH2 was determined in both pancreatic cancer tissues and cell lines. miR-124 or EZH2 was overexpressed in AsPC-1 and PANC1 cells. Then, the effects on cell viability. apoptosis, invasion, migration and epithelial mesenchymal transition were evaluated. Afterwards, the roles of miR-124 on the expression and function of EZH2 in pancreatic tumors were determined by dual luciferase reporter assay. Subsequently, miR-124 was transfected to bone marrow mesenchymal stromal cells (BM-MSCs), and the BM-MSCs derived exosomes were isolated and co-cultured with AsPC-1 and PANC1 cells, or injected into pancreatic cancer tumor-bearing mice.

Premature senescence in human melanocytes after exposure to solar UVR: An exosome and UV-miRNA connection

Ultraviolet radiation (UVR) can play two roles: induce cellular senescence and convert skin melanocytes into melanoma. To assess whether this conversion might rely on melanocytes having to first acquire a senescent phenotype, we studied the effects of physiological doses of UVR (UVA + UVB) on quiescent melanocytes in vitro. Repeated doses of UVR induced these melanocytes into a senescent-like state. Additionally, these cells secrete exosomes with specific miRNAs that differ in quantity from those of the un-irradiated melanocytes. Many of the exosomal miRNAs that were differentially enriched regulated genes comprising a "senescence core signature" and encoding factors of the senescence-messaging secretome (SASP), while a subset of the differentially reduced miRNAs targeted DNA repair genes that have been experimentally shown to be repressed in senescent melanocytes. Thus, the selection of specific miRNAs by exosomes and their release from melanocytes after exposure to UVR have activities in inducing these cells into premature senescence.

ER stress activates immunosuppressive network: implications for aging and Alzheimer's disease

The endoplasmic reticulum (ER) contains stress sensors which recognize the accumulation of unfolded proteins within the lumen of ER, and subsequently these transducers stimulate the unfolded protein response (UPR). The ER sensors include the IRE1, PERK, and ATF6 transducers which activate the UPR in an attempt to restore the quality of protein folding and thus maintain cellular homeostasis. If there is excessive stress, UPR signaling generates alarmins, e.g., chemokines and cytokines, which activate not only tissue-resident immune cells but also recruit myeloid and lymphoid cells into the affected tissues. ER stress is a crucial inducer of inflammation in many pathological conditions. A chronic low-grade inflammation and cellular senescence have been associated with the aging process and many age-related diseases, such as Alzheimer’s disease. Currently, it is known that immune cells can exhibit great plasticity, i.e., they are able to display both pro-inflammatory and anti-inflammatory phenotypes in a context-dependent manner. The microenvironment encountered in chronic inflammatory conditions triggers a compensatory immunosuppression which defends tissues from excessive inflammation. Recent studies have revealed that chronic ER stress augments the suppressive phenotypes of immune cells, e.g., in tumors and other inflammatory disorders. The activation of immunosuppressive network, including myeloid-derived suppressor cells (MDSC) and regulatory T cells (Treg), has been involved in the aging process and Alzheimer’s disease. We will examine in detail whether the ER stress-related changes found in aging tissues and Alzheimer’s disease are associated with the activation of immunosuppressive network, as has been observed in tumors and many chronic inflammatory diseases.

MiR-629-5p promotes the invasion of lung adenocarcinoma via increasing both tumor cell invasion and endothelial cell permeability

Tumor invasion underlies further metastasis, the leading cause for cancer-related deaths. Deregulation of microRNAs has been identified associated with the malignant behavior of various cancers, including lung adenocarcinoma (LUAD), the major subtype of lung cancer. Here, we showed the significantly positive correlation between miR-629-5p level and tumor invasion in LUAD specimens (n = 49). In a human LUAD metastasis mouse model, H1650 cells (high level of miR-629-5p) were more aggressive than A549 cells (low level of miR-629-5p) in vivo, including higher incidence of vascular invasion and pulmonary colonization. Ectopic expression of miR-629-5p in A549 cells also increased their invasive capability. Then we identified that miR-629-5p promotes LUAD invasion in a mode of dual regulation via tumor cells invasion and endothelial cells permeability, respectively. In tumor cells, miR-629-5p enhanced motility and invasiveness of tumor cells by directly targeting PPWD1 (a cyclophilin), which clinically related to tumor invasion in LUAD specimens. Restoring PPWD1 protein significantly attenuated the invasion-promoting effects of miR-629-5p. Besides, exosomal-miR-629-5p secreted from tumor cells could be transferred to endothelial cells and increased endothelial monolayers permeability by suppressing CELSR1 (a nonclassic-type cadherin), which had a low level in the endothelial cells of invasive LUAD specimens. Activating the expression of CELSR1 in endothelial cells markedly blocked the effect of miR-629-5p. Our study suggests the dual roles of miR-629-5p in tumor cells and endothelial cells for LUAD invasion, implying a therapeutic option to targeting miR-629-5p using the "one stone, two birds" strategy in LUAD.

Tumor microenvironment: Challenges and opportunities in targeting metastasis of triple negative breast cancer

Triple negative breast cancer (TNBC) is most aggressive subtype of breast cancers with high probability of metastasis as well as lack of specific targets and targeted therapeutics. TNBC is characterized with unique tumor microenvironment (TME), which differs from other subtypes. TME is associated with induction of proliferation, angiogenesis, inhibition of apoptosis and immune system suppression, and drug resistance. Exosomes are promising nanovesicles, which orchestrate the TME by communicating with different cells within TME. The components of TME including transformed ECM, soluble factors, immune suppressive cells, epigenetic modifications and re-programmed fibroblasts together hamper antitumor response and helps progression and metastasis of TNBCs. Therefore, TME could be a therapeutic target of TNBC. The current review presents latest updates on the role of exosomes in modulation of TME, approaches for targeting TME and combination of immune checkpoint inhibitors and target chemotherapeutics. Finally, we also discussed various phytochemicals that alter genetic, transcriptomic and proteomic profiles of TME along with current challenges and future implications. Thus, as TME is associated with the hallmarks of TNBC, the understanding of the impact of different components can improve the clinical benefits of TNBC patients.

Gold nanoparticle based double-labeling of melanoma extracellular vesicles to determine the specificity of uptake by cells and preferential accumulation in small metastatic lung tumors

Background

Extracellular vesicles (EVs) have shown great potential for targeted therapy, as they have a natural ability to pass through biological barriers and, depending on their origin, can preferentially accumulate at defined sites, including tumors. Analyzing the potential of EVs to target specific cells remains challenging, considering the unspecific binding of lipophilic tracers to other proteins, the limitations of fluorescence for deep tissue imaging and the effect of external labeling strategies on their natural tropism. In this work, we determined the cell-type specific tropism of B16F10-EVs towards cancer cell and metastatic tumors by using fluorescence analysis and quantitative gold labeling measurements. Surface functionalization of plasmonic gold nanoparticles was used to promote indirect labeling of EVs without affecting size distribution, polydispersity, surface charge, protein markers, cell uptake or in vivo biodistribution. Double-labeled EVs with gold and fluorescent dyes were injected into animals developing metastatic lung nodules and analyzed by fluorescence/computer tomography imaging, quantitative neutron activation analysis and gold-enhanced optical microscopy.

Results

We determined that B16F10 cells preferentially take up their own EVs, when compared with colon adenocarcinoma, macrophage and kidney cell-derived EVs. In addition, we were able to detect the preferential accumulation of B16F10 EVs in small metastatic tumors located in lungs when compared with the rest of the organs, as well as their precise distribution between tumor vessels, alveolus and tumor nodules by histological analysis. Finally, we observed that tumor EVs can be used as effective vectors to increase gold nanoparticle delivery towards metastatic nodules.

Conclusions

Our findings provide a valuable tool to study the distribution and interaction of EVs in mice and a novel strategy to improve the targeting of gold nanoparticles to cancer cells and metastatic nodules by using the natural properties of malignant EVs.

microRNA and exosome profiling in multiple sclerosis

New DNA sequencing technologies have uncovered non-coding RNA (ncRNA) as a major player in regulating cellular processes and can no longer be dismissed as "junk" or "dark" RNA. Among the ncRNA, microRNA (miRNA) is arguably the most extensively characterized category and a number of studies have implicated them in regulating critical functions that can influence autoimmune demyelination. Of specific interest to multiple sclerosis (MS), miRNA have been implicated in both regulating immune responses and myelination, thus making them an attractive candidate for both pharmacological intervention and as disease biomarkers. In addition, exosomes, small vesicles secreted by most cell types and present in all body fluids, have been also shown to play roles in immune signaling, inflammation and angiogenesis. Therefore, exosomes are also being explored as tools for therapeutic delivery and as biomarkers. This article reviews the recent advances in miRNA and exosome profiling in MS and experimental models.

Exosomes and Bone Disease

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Exosomes, which mediate cell-to-cell communications and provide a novel insight into information exchange, have drawn increasing attention in recent years. The homeostasis of bone metabolism is critical for bone health. The most common bone diseases such as osteoporosis, osteoarthritis and bone fractures have apparent correlations with exosomes. Accumulating evidence has suggested the potential regenerative capacities of stem cell-derived exosomes. In this review, we summarise the pathophysiological mechanism, clinical picture and therapeutic effects of exosomes in bone metabolism. We introduce the advantages and challenges in the application of exosomes. Although the exact mechanisms remain unclear, miRNAs seem to play major roles in the exosome.

Premetastatic niches, exosomes and circulating tumor cells: Early mechanisms of tumor dissemination and the relation to surgery

The physiological stress response to surgery promotes wound healing and functional recovery and includes the activation of neural, inflammatory and proangiogenic signaling pathways. Paradoxically, the same pathways also promote metastatic spread and growth of residual cancer. Human and animal studies show that cancer surgery can increase survival, migration and proliferation of residual tumor cells. To secure the survival and growth of disseminated tumor cells, the formation of premetastatic niches in target organs involves a complex interplay between microenvironment, immune system, circulating tumor cells, as well as chemical mediators and exosomes secreted by the primary tumor. This review describes the current understanding of the early mechanisms of dissemination, as well as how surgery may facilitate disease progression.

Exosome and Secretion: Action On?

Originally treated as part of a cellular waste, extracellular vesicles (EVs) are being shown to possess a vast variety of functions, of which exosome is the most studied one. Most cells, such as tumor cells, immunocytes, and fibroblasts can secrete exosomes, especially under certain stresses the amount is much higher, and the contents of exosome represent the status of the donor cells and the tumor microenvironment. As crucial transporters for cells' content exchange, much attention has been raised in the utilities of exosomes to suppress immune response, and to modify a microenvironment favorable for cancer progression. Exosomal immune checkpoints, such as programmed cell death ligand 1 (PD-L1), contribute to immunosuppression and are associated with anti-PD-1 response. Many forms of soluble immune checkpoint receptors have also been shown to influence efficacy mediated by their therapeutic antibodies. Therefore, targeting pro-tumorous exosomes may achieve antitumor effect supplementary to existing therapies. Exosome, itself natural liposome-like structure, allows it to be a potential drug delivery tool.

MicroRNA-769-5p Inhibits Pancreatic Ductal Adenocarcinoma Progression by Directly Targeting and Downregulating ETS Proto-Oncogene 1

Purpose

MicroRNA-769-5p (miR-769) is aberrantly expressed and plays crucial roles in non-small cell lung cancer and melanoma. However, the expression pattern, biological role, and mechanisms of action of miR-769 in pancreatic ductal adenocarcinoma (PDAC) are yet to be fully elucidated. Therefore, we attempted to determine the potential regulatory function of miR-769 in PDAC progression and to explore the underlying mechanisms in detail.

Methods

In this study, reverse-transcription quantitative polymerase chain reaction was carried out to determine the expression profile of miR-769 in PDAC. A series of experiments, including a Cell Counting Kit-8 assay, flow-cytometric analysis, Transwell migration and invasion assays, and a xenograft animal model, were applied to test whether miR-769 affects the malignancy of PDAC.

Results

We found that miR-769 was significantly underexpressed in PDAC tissues and cell lines. The low miR-769 expression significantly correlated with the TNM stage and lymph node metastasis. Patients with PDAC harboring low miR-769 expression showed shorter overall survival than did the patients with high miR-769 expression. Forced upregulation of miR-769 suppressed PDAC cell proliferation, migration, and invasion in vitro; promoted apoptosis in vitro; and hindered tumor growth in vivo. Experiments on the mechanism identified ETS proto-oncogene 1 (ETS1) as a direct target gene of miR-769 in PDAC cells. Furthermore, ETS1 turned out to be upregulated in PDAC tissue samples, and the upregulation of ETS1 negatively correlated with miR-769 expression. Moreover, ETS1 knockdown simulated the tumor-suppressive effects of miR-769 overexpression on PDAC cells. Besides, ETS1 reintroduction attenuated the antitumor actions of miR-769 upregulation in PDAC cells.

Conclusion

Our findings indicate that miR-769 performs tumor-suppressive functions in PDAC by directly targeting ETS1, and this miRNA may represent a potential therapeutic target for the development of anticancer therapies.