Exosomes in cancer theranostic: Diamonds in the rough

Heat Shock Proteins, a Double-Edged Sword: Significance in Cancer Progression, Chemotherapy Resistance and Novel Therapeutic Perspectives

Heat shock proteins (Hsps) are involved in one of the adaptive mechanisms protecting cells against environmental and metabolic stress. Moreover, the large role of these proteins in the carcinogenesis process, as well as in chemoresistance, was noticed. This review aims to draw attention to the possibilities of using Hsps in developing new cancer therapy methods, as well as to indicate directions for future research on this topic. In order to discuss this matter, a thorough review of the latest scientific literature was carried out, taking into account the importance of selected proteins from the Hsp family, including Hsp27, Hsp40, Hsp60, Hsp70, Hsp90 and Hsp110. One of the more characteristic features of all Hsps is that they play a multifaceted role in cancer progression, which makes them an obvious target for modern anticancer therapy. Some researchers emphasize the importance of directly inhibiting the action of these proteins. In turn, others point to their possible use in the design of cancer vaccines, which would work by inducing an immune response in various types of cancer. Due to these possibilities, it is believed that the use of Hsps may contribute to the progress of oncoimmunology, and thus help in the development of modern anticancer therapies, which would be characterized by higher effectiveness and lower toxicity to the patients.

Roles and application of exosomes in the development, diagnosis and treatment of gastric cancer

As important messengers of intercellular communication, exosomes can regulate local and distant cellular communication by transporting specific exosomal contents and can also promote or suppress the development and progression of gastric cancer (GC) by regulating the growth and proliferation of tumor cells, the tumor-related immune response and tumor angiogenesis. Exosomes transport bioactive molecules including DNA, proteins, and RNA (coding and noncoding) from donor cells to recipient cells, causing reprogramming of the target cells. In this review, we will describe how exosomes regulate the cellular immune response, tumor angiogenesis, proliferation and metastasis of GC cells, and the role and mechanism of exosome-based therapy in human cancer. We will also discuss the potential application value of exosomes as biomarkers in the diagnosis and treatment of GC and their relationship with drug resistance.

Exploring the Versatility of Exosomes: A Review on Isolation, Characterization, Detection Methods, and Diverse Applications

Extracellular vesicles (EVs) are crucial mediators of intercellular communication and can be classified based on their physical properties, biomolecular structure, and origin. Among EVs, exosomes have garnered significant attention due to their potential as therapeutic and diagnostic tools. Exosomes are released via fusion of multivesicular bodies on plasma membranes and can be isolated from various biofluids using methods such as differential ultracentrifugation, immune affinity capture, ultrafiltration, and size exclusion chromatography. Herein, an overview of different techniques for exosome characterization and isolation, as well as the diverse applications of exosome detection, including their potential use in drug delivery and disease diagnosis, is provided. Additionally, we discuss the emerging field of exosome detection by sensors, which offers an up-and-coming avenue for point-of-care diagnostic tools development. Overall, this review aims to provide a exhaustive and up-to-date summary of the current state of exosome research.

Exosomal MicroRNAs: An Emerging Important Regulator in Acute Lung Injury

Acute lung injury (ALI) is a clinically life-threatening form of respiratory failure with a mortality of 30%-40%. Acute respiratory distress syndrome is the aggravated form of ALI. Exosomes are extracellular lipid vesicles ubiquitous in human biofluids with a diameter of 30-150 nm. They can serve as carriers to convey their internal cargo, particularly microRNA (miRNA), to the target cells involved in cellular communication. In disease states, the quantities of exosomes and the cargo generated by cells are altered. These exosomes subsequently function as autocrine or paracrine signals to nearby or distant cells, regulating various pathogenic processes. Moreover, exosomal miRNAs from multiple stem cells can provide therapeutic value for ALI by regulating different signaling pathways. In addition, changes in exosomal miRNAs of biofluids can serve as biomarkers for the early diagnosis of ALI. This study aimed to review the role of exosomal miRNAs produced by different sources participating in various pathological processes of ALI and explore their potential significance in the treatment and diagnosis.

Hsp70-A Universal Biomarker for Predicting Therapeutic Failure in Human Female Cancers and a Target for CTC Isolation in Advanced Cancers

Heat shock protein 70 (Hsp70) is frequently overexpressed in many different tumor types. However, Hsp70 has also been shown to be selectively presented on the plasma membrane of tumor cells, but not normal cells, and this membrane form of Hsp70 (mHsp70) could be considered a universal tumor biomarker. Since viable, mHsp70-positive tumor cells actively release Hsp70 in lipid micro-vesicles, we investigated the utility of Hsp70 in circulation as a universal tumor biomarker and its potential as an early predictive marker of therapeutic failure. We have also evaluated mHsp70 as a target for the isolation and enumeration of circulating tumor cells (CTCs) in patients with different tumor entities. Circulating vesicular Hsp70 levels were measured in the peripheral blood of tumor patients with the compHsp70 ELISA. CTCs were isolated using cmHsp70.1 and EpCAM monoclonal antibody (mAb)-based bead approaches and characterized by immunohistochemistry using cytokeratin and CD45-specific antibodies. In two out of 35 patients exhibiting therapeutic failure two years after initial diagnosis of non-metastatic breast cancer, progressively increasing levels of circulating Hsp70 had already been observed during therapy, whereas levels in patients without subsequent recurrence remained unaltered. With regards to CTC isolation from patients with different tumors, an Hsp70 mAb-based selection system appears superior to an EpCAM mAb-based approach. Extracellular and mHsp70 can therefore serve as a predictive biomarker for therapeutic failure in early-stage tumors and as a target for the isolation of CTCs in various tumor diseases.

Heat-Shock Proteins in Leukemia and Lymphoma: Multitargets for Innovative Therapeutic Approaches

Heat-shock proteins (HSPs) are powerful chaperones that provide support for cellular functions under stress conditions but also for the homeostasis of basic cellular machinery. All cancer cells strongly rely on HSPs, as they must continuously adapt to internal but also microenvironmental stresses to survive. In solid tumors, HSPs have been described as helping to correct the folding of misfolded proteins, sustain oncogenic pathways, and prevent apoptosis. Leukemias and lymphomas also overexpress HSPs, which are frequently associated with resistance to therapy. HSPs have therefore been proposed as new therapeutic targets. Given the specific biology of hematological malignancies, it is essential to revise their role in this field, providing a more adaptable and comprehensive picture that would help design future clinical trials. To that end, this review will describe the different pathways and functions regulated by HSP27, HSP70, HSP90, and, not least, HSP110 in leukemias and lymphomas.

Extracellular vesicles production and proteomic cargo varies with incubation time and temperature

Extracellular vesicles (EVs) are heterogenous populations of proteolipid bi-layered vesicles secreted by cells as an important biological process. EVs cargo can reflect the cellular environmental conditions in which cells grow. The use of serum-free conditioned media to harvest EVs leads to stress-mediated cellular changes with longer incubation time and impacts EV production and functionality. This study aims to explore the role of incubation time and temperature on EV production and proteomic cargo. For this purpose, an optimized ultrafiltration-size exclusion chromatography-based technique is developed, which isolates small EVs ranging from 130 to 220 nm. The result shows higher EVs production in cancerous cells (K7M2) compared to noncancerous cells (NIH/3T3), which increases with longer incubation time and elevated temperature. Mass spectrometry-based proteomic characterization of EVs showed incubation time and temperature-dependent proteomic profile. A set of enriched EV proteins were identified in EVs isolated at nutrient-stress (72 h incubation time) and heat-stress (40 °C incubation temperature) environment. Enrichment of Serpinb1a in EVs isolated in heat stress was further validated via immunoblot. Gene enrichment analysis revealed that enriched EV proteins following nutrient stress were involved in negative regulation of transcription, response to oxidative stress, and protein folding. Likewise, enriched EV proteins following heat stress were involved in oxaloacetate and aspartate metabolism, and glutamate catabolic process. EVs isolated under nutrient stress showed pro-proliferative activity whereas EVs isolated under heat stress showed anti-proliferative activity. Our results show that incubation time and temperature can alter EV production, its proteomic cargo, and functionality, which can be used to design need-based standard isolation parameters for reproducible EV research.

Elevated circulating Hsp70 levels are correlative for malignancies in different mammalian species

Circulating Hsp70 levels were determined in feline and porcine cohorts using two different ELISA systems. These comparative animal models of larger organisms often reflect diseases, and especially malignant tumors, better than conventional rodent models. It is therefore essential to investigate the biology and utility of tumor biomarkers in animals such as cats and pigs. In this study, levels of free Hsp70 in the blood of cats with spontaneously occurring tumors were detected using a commercial Hsp70 ELISA (R&D Systems). Sub-analysis of different tumor groups revealed that animals with tumors of epithelial origin presented with significantly elevated circulating Hsp70 concentrations. In addition to free Hsp70 levels measured with the R&D Systems Hsp70 ELISA, levels of exosomal Hsp70 were determined using the compHsp70 ELISA in pigs. Both ELISA systems detected significantly elevated Hsp70 levels (R&D Systems: median 24.9 ng/mL; compHsp70: median 44.2 ng/mL) in the blood of a cohort of APC1311/+ pigs diagnosed with high-grade adenoma polyps, and the R&D Systems Hsp70 ELISA detected also elevated Hsp70 levels in animals with low-grade polyps. In contrast, in flTP53R167H pigs, suffering from malignant osteosarcoma, the compHsp70 ELISA (median 674.32 ng/mL), but not the R&D Systems Hsp70 ELISA (median 4.78 ng/mL), determined significantly elevated Hsp70 concentrations, indicating that in tumor-bearing animals, the dominant form of Hsp70 is of exosomal origin. Our data suggest that both ELISA systems are suitable for detecting free circulating Hsp70 levels in pigs with high-grade adenoma, but only the compHsp70 ELISA can measure elevated, tumor-derived exosomal Hsp70 levels in tumor-bearing animals.

CSF Biopsy in Glioma: A Brief Review

Glioma is the most common intracranial malignant tumor. Over the past several years, liquid biopsy in diagnosis and treatment of solid tumors have made many progressions, but there is still a gap from a large clinical application of liquid biopsy in glioma due to many limitations. However, in recent years, researchers have made many explorations into liquid biopsy in glioma. In the future, the liquid biopsy of glioma, especially cerebrospinal fluid, will have a broad prospect. In this review, we will discuss the current research progressions of CSF biopsy in glioma in recent years.

Current advances in the use of exosomes, liposomes, and bioengineered hybrid nanovesicles in cancer detection and therapy

Three major approaches of cancer therapy can be enunciated as delivery of biotherapeutics, tumor image analysis, and immunotherapy. Liposomes, artificial fat bubbles, are long known for their capacity to encapsulate a diverse range of bioactive molecules and release the payload in a sustained, stimuli-responsive manner. They have already been widely explored as a delivery vehicle for therapeutic drugs as well as imaging agents. They are also extensively being used in cancer immunotherapy. On the other hand, exosomes are naturally occurring nanosized extracellular vesicles that serve an important role in cell-cell communication. Importantly, the exosomes also have proven their capability to carry an array of active pharmaceuticals and diagnostic molecules to the tumor cells. Exosomes, being enriched with tumor antigens, have numerous immunomodulatory effects. Much to our intrigue, in recent times, efforts have been directed toward developing smart, bioengineered, exosome-liposome hybrid nanovesicles, which are augmented by the benefits of both vesicular systems. This review attempts to summarize the contemporary developments in the use of exosome and liposome toward cancer diagnosis, therapy, as a vehicle for drug delivery, diagnostic carrier for tumor imaging, and cancer immunotherapy. We shall also briefly reflect upon the recent advancements of the exosome-liposome hybrids in cancer therapy. Finally, we put forward future directions for the use of exosome/liposome and/or hybrid nanocarriers for accurate diagnosis and personalized therapies for cancers.

Hyperthermia combined with immune checkpoint inhibitor therapy in the treatment of primary and metastatic tumors

According to the difference in temperature, thermotherapy can be divided into thermal ablation and mild hyperthermia. The main advantage of thermal ablation is that it can efficiently target tumors in situ, while mild hyperthermia has a good inhibitory effect on distant metastasis. There are some similarities and differences between the two therapies with respect to inducing anti-tumor immune responses, but neither of them results in sustained systemic immunity. Malignant tumors (such as breast cancer, pancreatic cancer, nasopharyngeal carcinoma, and brain cancer) are recurrent, highly metastatic, and highly invasive even after treatment, hence a single therapy rarely resolves the clinical issues. A more effective and comprehensive treatment strategy using a combination of hyperthermia and immune checkpoint inhibitor (ICI) therapies has gained attention. This paper summarizes the relevant preclinical and clinical studies on hyperthermia combined with ICI therapies and compares the efficacy of two types of hyperthermia combined with ICIs, in order to provide a better treatment for the recurrence and metastasis of clinically malignant tumors.

Microfluidic Approaches for Affinity-Based Exosome Separation

As a subspecies of extracellular vesicles (EVs), exosomes have provided promising results in diagnostic and theranostic applications in recent years. The nanometer-sized exosomes can be extracted by liquid biopsy from almost all body fluids, making them especially suitable for mainly non-invasive point-of-care (POC) applications. To achieve this, exosomes must first be separated from the respective biofluid. Impurities with similar properties, heterogeneity of exosome characteristics, and time-related biofouling complicate the separation. This practical review presents the state-of-the-art methods available for the separation of exosomes. Furthermore, it is shown how new separation methods can be developed. A particular focus lies on the fabrication and design of microfluidic devices using highly selective affinity separation. Due to their compactness, quick analysis time and portable form factor, these microfluidic devices are particularly suitable to deliver fast and reliable results for POC applications. For these devices, new manufacturing methods (e.g., laminating, replica molding and 3D printing) that use low-cost materials and do not require clean rooms are presented. Additionally, special flow routes and patterns that increase contact surfaces, as well as residence time, and thus improve affinity purification are displayed. Finally, various analyses are shown that can be used to evaluate the separation results of a newly developed device. Overall, this review paper provides a toolbox for developing new microfluidic affinity devices for exosome separation.

Role of exosomes in lung cancer: A comprehensive insight from immunomodulation to theragnostic applications

Exosomes are 30 to 150 nm-diameter lipid bilayer-enclosed extracellular vesicles that enable cell-to-cell communication through secretion and uptake. The exosomal cargoes contain RNA, lipids, proteins, and metabolites which can be delivered to recipient cells in vivo. In a healthy lung, exosomes facilitate interaction between adaptive and innate immunity and help maintain normal lung physiology. However, tumor-derived exosomes in lung cancer (LC) can, on the other hand, restrict immune cell proliferation, cause apoptosis in activated CD8+ T effector cells, reduce natural killer cell activity, obstruct monocyte differentiation, and promote proliferation of myeloid-derived suppressor and regulatory T cells. In addition, exosomes in the tumor microenvironment may also play a critical role in cancer progression and the development of drug resistance. In this review, we aim to comprehensively examine the current updates on the role of exosomes in lung carcinogenesis and their potential application as a diagnostic, prognostic, and therapeutic tool in lung cancer.

Liquid Biopsy in Glioblastoma

Simple Summary

Glioblastoma is the most common and malignant primary brain tumor. Despite intensive research for new treatments, the survival of patients has not significantly improved in recent decades. Currently, glioblastoma is mainly diagnosed by neuroimaging techniques followed by histopathological and molecular analysis of the resected or biopsied tissue. Both imaging and tissue-based methods have, despite their advantages, some important limitations highlighting the necessity for alternative techniques such as liquid biopsy. It appears as an attractive and non-invasive alternative to support the diagnosis and the follow-up of patients with glioblastoma and to identify early recurrence. Liquid biopsy, primarily through blood tests, involves the detection and quantification of tumoral content released by tumors into the biofluids. The aim of the present review is to discuss the biological bases, the advantages, and the disadvantages of the most important circulating biomarkers so far proposed for glioblastoma.

Abstract

Glioblastoma (GBM) is the most common and aggressive primary brain tumor. Despite recent advances in therapy modalities, the overall survival of GBM patients remains poor. GBM diagnosis relies on neuroimaging techniques. However, confirmation via histopathological and molecular analysis is necessary. Given the intrinsic limitations of such techniques, liquid biopsy (mainly via blood samples) emerged as a non-invasive and easy-to-implement alternative that could aid in both the diagnosis and the follow-up of GBM patients. Cancer cells release tumoral content into the bloodstream, such as circulating tumor DNA, circulating microRNAs, circulating tumor cells, extracellular vesicles, or circulating nucleosomes: all these could serve as a marker of GBM. In this narrative review, we discuss the current knowledge, the advantages, and the disadvantages of each circulating biomarker so far proposed.

Molecular and Circulating Biomarkers in Patients with Glioblastoma

Glioblastoma is the most aggressive malignant tumor of the central nervous system with a low survival rate. The difficulty of obtaining this tumor material represents a major limitation, making the real-time monitoring of tumor progression difficult, especially in the events of recurrence or resistance to treatment. The identification of characteristic biomarkers is indispensable for an accurate diagnosis, the rigorous follow-up of patients, and the development of new personalized treatments. Liquid biopsy, as a minimally invasive procedure, holds promise in this regard. The purpose of this paper is to summarize the current literature regarding the identification of molecular and circulating glioblastoma biomarkers and the importance of their integration as a valuable tool to improve patient care.

The potential role of extracellular vesicles in bioactive compound-based therapy: A review of recent developments

Recent studies have explored the field of extracellular vesicles (EVs), driving an increasing interest in their application to human health. EVs have unique physicochemical traits to participate in intercellular communication, thus fostering the idea of using EVs to yield synergistic, preventive, and therapeutic effects. Many reports have shown that EVs contain natural bioactive compounds, such as lipids, proteins, RNA, and other active components that regulate biological processes, thereby contributing to human health. Therefore, in this review, we comprehensively elucidate various facets of the relationship between EVs and bioactive compounds that modulate EVs contents, including RNAs and proteins, discussing different forms of biological regulation. The use of EVs for cargo-loading bioactive compounds to exert biological functions and methods to load bioactive compounds into EVs are also discussed. This review highlighted the effect of EV-delivered bioactive compounds on several therapeutic mechanisms and applications, providing new insight into nutrition and pharmacology.

MicroRNAs: Novel players in the diagnosis and treatment of cancer cachexia (Review)

Cachexia denotes a complex metabolic syndrome featuring severe loss of weight, fatigue and anorexia. In total, 50-80% of patients suffering from advanced cancer are diagnosed with cancer cachexia, which contributes to 40% of cancer-associated mortalities. MicroRNAs (miRNAs) are non-coding RNAs capable of regulating gene expression. Dysregulated miRNA expression has been observed in muscle tissue, adipose tissue and blood samples from patients with cancer cachexia compared with that of samples from patients with cancer without cachexia or healthy controls. In addition, miRNAs promote and maintain the malignant state of systemic inflammation, while inflammation contributes to cancer cachexia. The present review discusses the role of miRNAs in the progression of cancer cachexia, and assess their diagnostic value and potential therapeutic value.

Exosome-Laden Hydrogels: A Novel Cell-free Strategy for In-situ Bone Tissue Regeneration

In-situ bone tissue regeneration, which harnesses cell external microenvironment and their regenerative potential to induce cell functions and bone reconstruction through some special properties of biomaterials, has been deeply developed. In which, hydrogel was widely applied due to its 3D network structure with high water absorption and mimicking native extracellular matrix (ECM). Additionally, exosomes can participate in a variety of physiological processes such as cell differentiation, angiogenesis and tissue repair. Therefore, a novel cell-free tissue engineering (TE) using exosome-laden hydrogels has been explored and developed for bone regeneration in recent years. However, related reviews in this field are limited. Therefore, we elaborated on the shortcomings of traditional bone tissue engineering, the challenges of exosome delivery and emphasized the advantages of exosome-laden hydrogels for in-situ bone tissue regeneration. The encapsulation strategies of hydrogel and exosomes are listed, and the research progress and prospects of bioactive hydrogel composite system for continuous delivery of exosomes for in-situ bone repair are also discussed in this review.

Exosomes for Regulation of Immune Responses and Immunotherapy

Exosomes are membrane-enveloped nanosized (30–150 nm) extracellular vesicles of endosomal origin produced by almost all cell types and encompass a multitude of functioning biomolecules. Exosomes have been considered crucial players of cell-to-cell communication in physiological and pathological conditions. Accumulating evidence suggests that exosomes can modulate the immune system by delivering a plethora of signals that can either stimulate or suppress immune responses, which have potential applications as immunotherapies for cancer and autoimmune diseases. Here, we discuss the current knowledge about the active biomolecular components of exosomes that contribute to exosomal function in modulating different immune cells and also how these immune cell-derived exosomes play critical roles in immune responses. We further discuss the translational potential of engineered exosomes as immunotherapeutic agents with their advantages over conventional nanocarriers for drug delivery and ongoing clinical trials.

PD-L1 in circulating exosomes of Merkel cell carcinoma

INTRODUCTION

Exosomes, as potential circulated biomarkers, have recently become a topic of interest in the field of oncology. Immune checkpoint molecule PD-L1 has recently been detected in circulating exosomes from cancer patients. The purpose of this work was to evaluate PD-L1 levels in circulating exosomes (Exo-PD-L1) isolated from patients' plasma suffering from Merkel cell carcinoma (MCC).

METHOD

We conducted a prospective bicentric cohort study. PD-L1 was analyzed in circulating exosomes from plasma samples of patients suffering from MCC stage I to IV (according to the AJCC 8).

RESULTS

Exosomes from 34 patients corresponding to 66 samples were analyzed. PD-L1 was identified in circulating exosomes of MCC patients. Exo-PD-L1 levels of MCC patients were similar to healthy donors and lower than other cancers such as melanoma. Exo-PD-L1 levels tended to be higher in MCC patients with distant metastases. Furthermore, Exo-PD-L1 levels did not significantly vary over the course of the disease whatever the disease course or the response to treatment.

DISCUSSION

This study assessed the presence of PD-L1 in circulating exosomes of MCC patients. The low levels of Exo-PD-L1 and small changes over the course of the disease may be due to the metastatic dissemination of MCC, which is mainly through the skin and lymph nodes rather than blood.

CONCLUSION

PD-L1 was identified in circulating exosomes of MCC patients and tends to be higher in advanced disease. This preliminary study is a proof of concept of PD-L1 detection in circulating exosomes of MCC patients.

[Extracellular vesicles: Definition, isolation and characterization]

Extracellular vesicles (EVs) originate from eukaryotic and prokaryotic cells and play a crucial role in intercellular communications. They are found in the environment of cells and tissues, and contribute to the complexity of different biological media, in particular biofluids. Due to their high diversity of cell origin, size range, concentration and composition, EVs offer some of the most important challenges in (pre-)analytical fields. To tackle these challenges, many works deal with the development and implementation of a wide variety of approaches, technologies and methodologies to enrich, isolate, quantify and characterize EVs and their subsets. Nevertheless, other components such as lipoproteins or viruses in complex samples, can interfere with EVs qualification, and make difficult, even today, to standardize biochemical and physical approaches for this purpose. The present chapter presents EVs and the mostly used technics for their isolation and characterization. Performances of methods in terms of resolution, discrimination, throughput and also ability to be or not applied in clinics, are also discussed.

Autophagy induced by Schwann cell-derived exosomes promotes recovery after spinal cord injury in rats

Spinal cord injury (SCI) is catastrophic to humans and society. However, there is currently no effective treatment for SCI. Autophagy is known to serve critical roles in both the physiological and pathological processes of the body, but its facilitatory and/or deleterious effects in SCI are yet to be completely elucidated. This study aimed to use primary Schwann cell-derived exosomes (SCDEs) to treat rats after SCI. In the present study, SCDEs were purified and their efficacy in ameliorating the components of SCI was examined. Using both in vivo and in vitro experiments, it was demonstrated that SCDEs increased autophagy and decreased apoptosis after SCI, which promoted axonal protection and the recovery of motor function. Furthermore, it was discovered that an increased number of SCDEs resulted in a decreased expression level of EGFR, which subsequently inhibited the Akt/mTOR signaling pathway, which upregulated the level of autophagy to ultimately induce microtubule acetylation and polymerization. Collectively, the present study identified that SCDEs could induce axonal protection after SCI by increasing autophagy and decreasing apoptosis, and it was suggested that this may involve the EGFR/Akt/mTOR signaling pathway.

Effects of Tumor-Derived Exosome Programmed Death Ligand 1 on Tumor Immunity and Clinical Applications

Programmed death ligand 1 (PD-L1) is a typical immune surface protein that binds to programmed cell death 1 (PD-1) on T cells through its extracellular domain. Subsequently, T cell activity is inhibited, and tumor immune tolerance is enhanced. Anti-PD-1/PD-L1 immune checkpoint therapy blocks the combination of PD-1/PD-L1 and rejuvenates depleted T cells, thereby inhibiting tumor growth. Exosomes are biologically active lipid bilayer nanovesicles secreted by various cell types, which mediate signal communication between cells. Studies have shown that PD-L1 can not only be expressed on the surface of tumor cells, immune cells, and other cells in the tumor microenvironment, but also be released from tumor cells and exist in an extracellular form. In particular, exosome PD-L1 plays an unfavorable role in tumor immunosuppression. The immunomodulatory effect of exosome PD-L1 and its potential in fluid diagnosis have attracted our attention. This review aims to summarize the available evidence regarding the biological characteristics of exosome PD-L1 in tumor immunity, with a particular focus on the mechanisms in different cancers and clinical prospects. In addition, we also summarized the current possible and effective detection methods for exosome PD-L1 and proposed that exosome PD-L1 has the potential to become a target for overcoming anti-PD-1/PD-L1 antibody treatment resistance.

Application of immunotherapy based on dendritic cells stimulated by tumor cell-derived exosomes in a syngeneic breast tumor mouse model

We here evaluated the therapeutic effect of tumor cell-derived exosomes (TEXs)-stimulated dendritic cells (DCs) in a syngeneic orthotopic breast tumor model. The DC line DC2.4 and breast cancer cell line E0771 originally isolated from C57BL/6 mice were used. E0771 cells stably expressing the exosomal CD63-RFP or luciferase (Luc) and DC2.4 cells stably expressing GFP were produced using lentivirus. TEXs were purified from conditioned medium of E0771/CD63-RFP cells. Breast tumor model was established by injecting E0771/Luc cells into mammary gland fat pad of mice. TEXs contained immune modulatory molecules such as HSP70, HSP90, MHC I, MHC II, TGF-β, and PD-L1. TEXs were easily taken by DC2.4 cells, resulting in a significant increase in the in vitro proliferation and migration abilities of DC2.4 cells, accompanied by the upregulation of CD40. TEX-DC-treated group exhibited a decreased tumor growth compared with control group. CD8⁺ cells were more abundant in the tumors and lymph nodes of TEX-DC-treated group than in those of control group, whereas many CD4⁺ or FOXP3+ cells were localized in those of control group. Our results suggest a potential application of TEX-DC-based cancer immunotherapy.

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TEXs contained immune modulatory molecules such as HSP70, HSP90, MHC I, MHC II, TGF-β, and PD-L1. .

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TEXs increased the proliferation and migration capacities of dendritic cells.

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TEXs up regulated CD40 molecule on dendritic cells.

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TEX-stimulated dendritic cells suppressed tumor growth, with accompanying increase in CD8⁺ T cell infiltration.

Heat shock proteins and exosomes in cancer theranostics

Heat shock proteins (HSPs) are a superfamily of molecular chaperones that were discovered through their ability to be induced by different stresses including heat shock. Other than their function as chaperones in proteins homeostasis, HSPs have been shown to inhibit different forms of cell death and to participate in cell proliferation and differentiation processes. Because cancer cells have to rewire their metabolism, they require a high amount of these stress-inducible chaperones for their survival. Therefore, HSPs are unusually abundant in cancer cells where they have oncogene-like functions. In cancer, HSPs have been involved in the regulation of apoptosis, immune responses, angiogenesis, metastasis and treatment resistance. Recently, HSPs have been shown to be secreted through exosomes by cancer cells. These tumor-derived exosomes can be used as circulating markers: HSP-exosomes have been reported as biomarkers of cancer dissemination, response to therapy and/or patient outcome. A new range of functions, mostly in modulation of anticancer immune responses, have been described for these extracellular HSPs. In this review, we will describe those recently reported functions of HSP-exosomes that makes them both targets for anticancer therapeutics and biomarkers for the monitoring of the disease. We will also discuss their emerging interest in cancer vaccines.

Hsp70 in Liquid Biopsies-A Tumor-Specific Biomarker for Detection and Response Monitoring in Cancer

In contrast to normal cells, tumor cells of multiple entities overexpress the Heat shock protein 70 (Hsp70) not only in the cytosol, but also present it on their plasma membrane in a tumor-specific manner. Furthermore, membrane Hsp70-positive tumor cells actively release Hsp70 in small extracellular vesicles with biophysical characteristics of exosomes. Due to conformational changes of Hsp70 in a lipid environment, most commercially available antibodies fail to detect membrane-bound and vesicular Hsp70. To fill this gap and to assess the role of vesicular Hsp70 in circulation as a potential tumor biomarker, we established the novel complete (comp)Hsp70 sandwich ELISA, using two monoclonal antibodies (mAbs), that is able to recognize both free and lipid-associated Hsp70 on the cell surface of viable tumor cells and on small extracellular vesicles. The epitopes of the mAbs cmHsp70.1 (aa 451-461) and cmHsp70.2 (aa 614-623) that are conserved among different species reside in the substrate-binding domain of Hsp70 with measured affinities of 0.42 nM and 0.44 nM, respectively. Validation of the compHsp70 ELISA revealed a high intra- and inter-assay precision, linearity in a concentration range of 1.56 to 25 ng/mL, high recovery rates of spiked liposomal Hsp70 (>84%), comparable values between human serum and plasma samples and no interference by food intake or age of the donors. Hsp70 concentrations in the circulation of patients with glioblastoma, squamous cell or adeno non-small cell lung carcinoma (NSCLC) at diagnosis were significantly higher than those of healthy donors. Hsp70 concentrations dropped concomitantly with a decrease in viable tumor mass upon irradiation of patients with approximately 20 Gy (range 18-22.5 Gy) and after completion of radiotherapy (60-70 Gy). In summary, the compHsp70 ELISA presented herein provides a sensitive and reliable tool for measuring free and vesicular Hsp70 in liquid biopsies of tumor patients, levels of which can be used as a tumor-specific biomarker, for risk assessment (i.e., differentiation of grade III vs. IV adeno NSCLC) and monitoring of therapeutic outcomes.

Role of Extracellular Vesicles in Compromising Cellular Resilience to Environmental Stressors

Extracellular vesicles (EVs), like exosomes, are nanosized membrane-enveloped vesicles containing different bioactive cargo, such as proteins, lipids, mRNA, miRNA, and other small regulatory RNAs. Cell-derived EVs, including EVs originating from stem cells, may capture components from damaged cells or cells impacted by therapeutic treatments. Interestingly, EVs derived from stem cells can be preconditioned to produce and secrete EVs with different therapeutic properties, particularly with respect to heat-shock proteins and other molecular cargo contents. This behavior is consistent with stem cells that also respond differently to various microenvironments. Heat-shock proteins play roles in cellular protection and mediate cellular resistance to radiotherapy, chemotherapy, and heat shock. This review highlights the possible roles EVs play in mediating cellular plasticity and survival when exposed to different physical and chemical stressors, with a special focus on the respiratory distress due to the air pollution.

Circulating Biomarkers for Glioma: A Review

Accurate circulating biomarkers have potential clinical applications in population screening, tumor subclassification, monitoring tumor status, and the delivery of individualized treatments resulting from tumor genotyping. Recently, significant progress has been made within this field in several cancer types, but despite the many potential benefits, currently there is no validated circulating biomarker test for patients with glioma. A number of circulating factors have been examined, including circulating tumor cells, cell-free DNA, microRNA, exosomes, and proteins from both peripheral blood and cerebrospinal fluid with variable results. In the following article, we provide a narrative review of the current evidence pertaining to circulating biomarkers in patients with glioma, including discussion of the advantages and challenges encountered with the current methods used for discovery. Additionally, the potential clinical applications are described with reference to the literature.

Microglial Exosome miR-7239-3p Promotes Glioma Progression by Regulating Circadian Genes

Glioma-associated microglial cells, a key component of the tumor microenvironment, play an important role in glioma progression. In this study, the mouse glioma cell line GL261 and the mouse microglia cell line BV2 were chosen. First, circadian gene expression in glioma cells co-cultured with either M1 or M2 microglia was assessed and the exosomes of M2-polarized and unpolarized BV-2 microglia were extracted. Subsequently, we labeled the exosomes with PKH67 and treated GL261 cells with them to investigate the exosome distribution. GL261 cell phenotypes and related protein expression were used to explore the role of M2 microglial exosomes in gliomas. Then a specific miR-7239-3p inhibitor was added to verify miR-7239-3p functions. Finally, the mouse subcutaneous tumorigenic model was used to verify the tumorigenic effect of M2 microglial exosomes in vivo. Our results showed that in gliomas co-cultured with M2 microglia, the expression of the BMAL1 protein was decreased (P < 0.01), while the expression of the CLOCK protein was increased (P < 0.05); opposite results were obtained in gliomas co-cultured with M1 microglia. After treatment with M2 microglial exosomes, the apoptosis of GL261 cells decreased (P < 0.001), while the viability, proliferation, and migration of GL261 cells increased. Increased expression of N-cadherin and Vimentin, and decreased E-cadherin expression occurred upon treatment with M2 microglial exosomes. Addition of an miR-7239-3p inhibitor to M2 microglial exosomes reversed these results. In summary, we found that miR-7239-3p in the glioma microenvironment is recruited to glioma cells by exosomes and inhibits Bmal1 expression. M2 microglial exosomes promote the proliferation and migration of gliomas by regulating tumor-related protein expression and reducing apoptosis.

The Interplay of Exosomes and NK Cells in Cancer Biology

Natural killer (NK) cells are innate lymphoid cells involved in tumor surveillance. These immune cells have the potential to fight cancer growth and metastasis, as such, their deregulation can result in tumor immune escape. Recently exosomes were described as mediators of intercellular communication between cancer and NK cells. The exact role of this subclass of extracellular vesicles (EVs), which transport genetic and molecular material to recipient cells, in NK cell biology in the context of cancer, is still an open question. Several reports have demonstrated that tumor-derived exosomes (TDEs) can exert immunomodulatory activities, including immunosuppression, thus promoting cancer progression. Some reports demonstrate that the interplay between cancer exosomes and NK cells allows tumors to escape immune regulation. On the other hand, tumor exosomes were also described to activate NK cells. Additionally, studies show that NK cell exosomes can modulate the immune system, opening up their potential as an immunotherapeutic strategy for cancer treatment. Our review will focus on the reprogramming effect of cancer exosomes on NK cells, and the immunotherapeutic potential of NK cells-derived exosomes.

Stem cell-derived exosomes: Role in the pathogenesis and treatment of atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory vascular disease characterized by the accumulation of lipids and inflammatory debris in large arteries, high morbidity, and AS-related disease mortality. AS is a complex process, involving endothelial cell dysfunction and inflammation, smooth muscle cell proliferation, and macrophage activation. However, the currently available therapies for AS are not ideal, thus requiring development of novel treatment strategies. Exosomes are bi-lipid membranous extracellular containing multifarious cargo, such as proteins, lipids, micro ribonucleic acid (miRNAs), messenger RNAs, and long non-coding RNAs. Moreover, exosomes reportedly participate in various AS processes. Specifically, stem cell-derived exosomes can regulate the occurrence and development of AS, exhibiting the ability to overcome the limitations associated with AS treatment and stem cell therapy. In this paper, we review the pathological mechanism of AS and discuss the role of exosomes and stem cell-derived exosomes in AS progression. We conclude by suggesting new therapeutic strategies for treating AS with stem cell-derived exosomes in the hope of improving the clinical treatment of AS.

Exosomal HSP70 for Monitoring of Frontotemporal Dementia and Alzheimer's Disease: Clinical and FDG-PET Correlation

We aimed to study the expression of circulating heat-shock protein HSP70 and exosomes in plasma of a cohort of patients with Alzheimer's disease (AD) and frontotemporal dementia (FTD) at different stages. We performed correlations with clinical scales and FDG-PET. HSP70 levels were higher within exosomes than free in plasma. Moderate correlations were found between exosomal HSP70 and CDR, FTLD-CDR, and extension of hypometabolism. Our results suggest modifications in the level of exosomal HSP70 during the course of neurodegeneration, regardless of AD or FTD, and therefore HSP70 could have a potential role in the follow-up of these disorders.

B7-H3 in Medulloblastoma-Derived Exosomes; A Novel Tumorigenic Role

(1) Aim: Medulloblastoma is the most common aggressive pediatric cancer of the central nervous system. Improved therapies are necessary to improve life outcomes for medulloblastoma patients. Exosomes are a subset of extracellular vesicles that are excreted outside of the cell, and can transport nucleic acids and proteins from donor cells to nearby recipient cells of the same or dissimilar tissues. Few publications exist exploring the role that exosomes play in medulloblastoma pathogenesis. In this study, we found B7-H3, an immunosuppressive immune checkpoint, present in D283 cell-derived exosomes. (2) Methods: Utilizing mass spectrometry and immunoblotting, the presence of B7-H3 in D283 control and B7-H3 overexpressing exosomes was confirmed. Exosomes were isolated by Systems Biosciences from cultured cells as well as with an isolation kit that included ultracentrifugation steps. Overlay experiments were performed to determine mechanistic impact of exosomes on recipient cells by incubating isolated exosomes in serum-free media with target cells. Impact of D283 exosome incubation on endothelial and UW228 medulloblastoma cells was assessed by immunoblotting. Immunocytochemistry was employed to visualize exosome fusion with recipient cells. (3) Results: Overexpressing B7-H3 in D283 cells increases exosomal production and size distribution. Mass spectrometry revealed a host of novel, pathogenic molecules associated with B7-H3 in these exosomes including STAT3, CCL5, MMP9, and PI3K pathway molecules. Additionally, endothelial and UW228 cells incubated with D283-derived B7-H3-overexpressing exosomes induced B7-H3 expression while pSTAT1 levels decreased in UW228 cells. (4) Conclusions: In total, our results reveal a novel role in exosome production and packaging for B7-H3 that may contribute to medulloblastoma progression.

Engineering Smart Targeting Nanovesicles and Their Combination with Hydrogels for Controlled Drug Delivery

Smart engineered and naturally derived nanovesicles, capable of targeting specific tissues and cells and delivering bioactive molecules and drugs into them, are becoming important drug delivery systems. Liposomes stand out among different types of self-assembled nanovesicles, because of their amphiphilicity and non-toxic nature. By modifying their surfaces, liposomes can become stimulus-responsive, releasing their cargo on demand. Recently, the recognized role of exosomes in cell-cell communication and their ability to diffuse through tissues to find target cells have led to an increase in their usage as smart delivery systems. Moreover, engineering "smarter" delivery systems can be done by creating hybrid exosome-liposome nanocarriers via membrane fusion. These systems can be loaded in naturally derived hydrogels to achieve sustained and controlled drug delivery. Here, the focus is on evaluating the smart behavior of liposomes and exosomes, the fabrication of hybrid exosome-liposome nanovesicles, and the controlled delivery and routes of administration of a hydrogel matrix for drug delivery systems.

Extracellular Chaperones as Novel Biomarkers of Overall Cancer Progression and Efficacy of Anticancer Therapy

Exosomal heat shock proteins (Hsps) are involved in intercellular communication both in physiological and pathological conditions. They play a role in key processes of carcinogenesis including immune system regulation, cell differentiation, vascular homeostasis and metastasis formation. Thus, exosomal Hsps are emerging biomarkers of malignancies and possible therapeutic targets. Adolescents and young adults (AYAs) are patients aged 15–39 years. This age group, placed between pediatric and adult oncology, pose a particular challenge for cancer management. New biomarkers of cancer growth and progression as well as prognostic factors are desperately needed in AYAs. In this review, we attempted to summarize the current knowledge on the role of exosomal Hsps in selected solid tumors characteristic for the AYA population and/or associated with poor prognosis in this age group. These included malignant melanoma, brain tumors, and breast, colorectal, thyroid, hepatocellular, lung and gynecological tract carcinomas. The studies on exosomal Hsps in these tumors are limited; however; some have provided promising results. Although further research is needed, there is potential for future clinical applications of exosomal Hsps in AYA cancers, both as novel biomarkers of disease presence, progression or relapse, or as therapeutic targets or tools for drug delivery.

Monitoring HSP70 exosomes in cancer patients' follow up: a clinical prospective pilot study

Exosomes are nanovesicles released by all cells that can be found in the blood. A key point for their use as potential biomarkers in cancer is to differentiate tumour-derived exosomes from other circulating nanovesicles. Heat shock protein-70 (HSP70) has been shown to be abundantly expressed by cancer cells and to be associated with bad prognosis. We previously showed that exosomes derived from cancer cells carried HSP70 in the membrane while those from non-cancerous cells did not. In this work, we opened a prospective clinical pilot study including breast and lung cancer patients to determine whether it was possible to detect and quantify HSP70 exosomes in the blood of patients with solid cancers. We found that circulating exosomal HSP70 levels, but not soluble HSP70, reflected HSP70 content within the tumour biopsies. Circulating HSP70 exosomes increased in metastatic patients compared to non-metastatic patients or healthy volunteers. Further, we demonstrated that HSP70-exosome levels correlated with the disease status and, when compared with circulating tumour cells, were more sensitive tumour dissemination predictors. Finally, our case studies indicated that HSP70-exosome levels inversely correlated with response to the therapy and that, therefore, monitoring changes in circulating exosomal HSP70 might be useful to predict tumour response and clinical outcome.

Exosomes and Female Infertility

BACKGROUND

Exosomes are small Extracellular Vesicles (EVs) (40-100 nm) secreted by living cells and mediate the transmission of information between cells. The number and contents of exosomes are associated with diseases such as inflammatory diseases, cancer, metabolic diseases and what we are focusing in this passage-female infertility.

OBJECTIVE

This review focused on the role of exosomes in oocyte development, declined ovarian function, PCOS, uterine diseases, endometrial receptivity and fallopian tube dysfunction in the female.

METHODS

We conducted an extensive search for research articles involving relationships between exosomes and female infertility on the bibliographic database.

RESULTS

It has been reported that exosomes can act as a potential therapeutic device to carry cargoes to treat female infertility. However, the pathophysiological mechanisms of exosomes in female infertility have not been entirely elucidated. Further researches are needed to explore the etiology and provide evidence for potential clinical treatment.

CONCLUSIONS

This review systematically summarized the role exosomes play in female infertility and its potential as drug delivery.

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.

Membrane-bound exosomal HSP70 as a biomarker for detection and monitoring of malignant solid tumours: a pilot study

Background

Cancer is the second leading cause of death globally. Early detection and disease management lead to a better survival rate. Consequently, discovery of novel methods in cancer early diagnosis is a field of active research. Minimally invasive liquid biopsies are generating growing interest. Circulating tumour cells (CTCs) have been identified in patients' blood; nevertheless, these cells are rare and heterogeneous. Exosomes are extracellular nanovesicles released into the extracellular environment via the endosomal vesicle pathway and found in different body fluids. Exosomes deliver bioactive cargo such as proteins, mRNA and miRNA to recipient cells in the tumour environment. We have recently shown that heat shock protein 70 (HSP70) is detected in the membrane of tumour-derived exosomes, in contrast to normal cells. One single cancer cell can release thousands of HSP70-exosomes, facilitating detection. The aim of the pilot study ExoDiag is to determine whether it is possible to detect and quantify HSP70-exosomes in blood in patients with solid cancers.

Methods

Bicentric pilot study that will include 60 adult patients with metastatic and non-metastatic solid tumours and 20 healthy volunteers. Exosomes will be isolated from blood and urine samples, and HSP70 concentration will be determined. Patients will be followed for 1 year. The study is sponsored by Georges-François Leclerc Centre and is currently ongoing.

Discussion

We expect to demonstrate that HSP70-exosomes could be a powerful tool to diagnose cancer and to guide clinicians in therapeutic decision-making, improving patient's care.

Trial Registration

ClinicalTrials.gov identifier NCT02662621. Registered 20 January 2016, https://clinicaltrials.gov/ct2/show/study/NCT02662621?term=NCT02662621&rank=1.

Tracking the evolution of circulating exosomal-PD-L1 to monitor melanoma patients

In the era of immunotherapies there is an urgent need to implement the use of circulating biomarkers in clinical practice to facilitate personalized therapy and to predict treatment response. We conducted a prospective study to evaluate the usefulness of circulating exosomal-PD-L1 in melanoma patients' follow-up. We studied the dynamics of exosomal-PD-L1 from 100 melanoma patients by using an enzyme-linked immunosorbent assay. We found that PD-L1 was secreted through exosomes by melanoma cells. Exosomes carrying PD-L1 had immunosuppressive properties since they were as efficient as the cancer cell from which they derive at inhibiting T-cell activation. In plasma from melanoma patients, the level of PD-L1 (n= 30, median 64.26 pg/mL) was significantly higher in exosomes compared to soluble PD-L1 (n= 30, 0.1 pg/mL). Furthermore, exosomal-PD-L1 was detected in all patients whereas only 67% of tumour biopsies were PD-L1 positive. Although baseline exosomal-PD-L1 levels were not associated with clinic-pathologic characteristics, their variations after the cures (ΔExoPD-L1) correlated with the tumour response to treatment. A ΔExoPD-L1 cut-off of> 100 was defined, yielding an 83% sensitivity, a 70% specificity, a 91% positive predictive value and 54% negative predictive values for disease progression. The use of the cut-off allowed stratification in two groups of patients statistically different concerning overall survival and progression-free survival. PD-L1 levels in circulating exosomes seem to be a more reliable marker than PD-L1 expression in tumour biopsies. Monitoring of circulating exosomal-PD-L1 may be useful to predict the tumour response to treatment and clinical outcome.

The significance of exosomes in the development and treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most commonmalignancy. Exsome plays a significant role in the elucidation of signal transduction pathways between hepatoma cells, angiogenesis and early diagnosis of HCC. Exosomes are small vesicular structures that mediate interaction between different types of cells, and contain a variety of components (including DNA, RNA, and proteins). Numerous studies have shown that these substances in exosomes are involved in growth, metastasis and angiogenesis in liver cancer, and then inhibited the growth of liver cancer by blocking the signaling pathway of liver cancer cells. In addition, the exosomal substances could also be used as markers for screening early liver cancer. In this review, we summarized to reveal the significance of exosomes in the occurrence, development, diagnosis and treatment of HCC, which in turn might help us to further elucidate the mechanism of exosomes in HCC, and promote the use of exosomes in the clinical diagnosis and treatment of HCC.

Nanoparticle-based biosensors for detection of extracellular vesicles in liquid biopsies

Selecting the appropriate nanoparticle, functionalization chemistry and sensing methodology can speed up the translation of liquid biopsies into the clinic.

Exosomal miRNA: Small Molecules, Big Impact in Colorectal Cancer

Colorectal cancer (CRC) is one of the major causes of cancer-related deaths worldwide. Tumor microenvironment (TME) contains many cell types including stromal cells, immune cells, and endothelial cells. The TME modulation explains the heterogeneity of response to therapy observed in patients. In this context, exosomes are emerging as major contributors in cancer biology. Indeed, exosomes are implicated in tumor proliferation, angiogenesis, invasion, and premetastatic niche formation. They contain bioactive molecules such as proteins, lipids, and RNAs. More recently, many studies on exosomes have focused on miRNAs, small noncoding RNA molecules able to influence protein expression. In this review, we describe miRNAs transported by exosomes in the context of CRC and discuss their influence on TME and their potential as circulating biomarkers. This overview underlines emerging roles for exosomal miRNAs in cancer research for the near future.

Heat Shock Proteins Are Essential Components in Transformation and Tumor Progression: Cancer Cell Intrinsic Pathways and Beyond

Heat shock protein (HSP) synthesis is switched on in a remarkably wide range of tumor cells, in both experimental animal systems and in human cancer, in which these proteins accumulate in high levels. In each case, elevated HSP concentrations bode ill for the patient, and are associated with a poor outlook in terms of survival in most cancer types. The significance of elevated HSPs is underpinned by their essential roles in mediating tumor cell intrinsic traits such as unscheduled cell division, escape from programmed cell death and senescence, de novo angiogenesis, and increased invasion and metastasis. An increased HSP expression thus seems essential for tumorigenesis. Perhaps of equal significance is the pronounced interplay between cancer cells and the tumor milieu, with essential roles for intracellular HSPs in the properties of the stromal cells, and their roles in programming malignant cells and in the release of HSPs from cancer cells to influence the behavior of the adjacent tumor and infiltrating the normal cells. These findings of a triple role for elevated HSP expression in tumorigenesis strongly support the targeting of HSPs in cancer, especially given the role of such stress proteins in resistance to conventional therapies.

7Hsp70 serum levels in pet dogs-a potential diagnostic biomarker for spontaneous round cell tumors

The concentration of circulating heat shock protein 70 (Hsp70) was measured in liquid biopsies of canine tumor patients as a potential biomarker. Compared with rodent tumor models, spontaneously occurring tumors in pet dogs reflect the clinical situation of human patients better, as dogs cohabitate with their owners in the same environment, reach a much older age than rodents, can provide blood samples much more frequently, and receive up-to-date medical care and, similar to humans, their tumors show a high genetic heterogeneity. Due to the species-specific sequence homology of human and canine Hsp70, two human enzyme-linked immunosorbent assay (ELISA) systems (R&D and lipHsp70) were used to measure canine Hsp70 concentrations in serum and plasma. In general, higher Hsp70 concentrations were found in serum compared with plasma samples of dogs, and the lipHsp70 ELISA detected higher peak concentrations of Hsp70 in a broader range than the R&D ELISA. Compared with a tumor-free control group, serum Hsp70 concentrations were higher in tumor-bearing dogs, irrespective of breed, age, body weight, and gender. A sub-classification of the different tumors according to their cytological characteristics revealed significantly elevated Hsp70 serum concentrations in dogs with round cell tumors (p < 0.01), a heterogeneous group of malignancies with hematopoietic origin such as mast cells, plasma cells, lymphocytes, histiocytes, and melanomas. Future studies with larger patient cohorts and well-defined tumor sizes are necessary to elucidate the role of serum Hsp70 as a biomarker for tumor detection and monitoring of outcome in pet animals.

Different Types of Cellular Stress Affect the Proteome Composition of Small Extracellular Vesicles: A Mini Review

Extracellular vesicles (EVs) are well-known mediators of the cellular response to different stress factors, yet the exact mechanism of their action remains unclear. Hence, the characterization of their cargo, consisting of proteins, nucleic acids, and different classes of metabolites, helps to elucidate an understanding of their function in stress-related communication. The unexpected diversity and complexity of these vesicles requires the incorporation of multiple technologically advanced approaches in EV-oriented studies. This mini review focuses on the invaluable role of proteomics, especially mass spectrometry-based tools, in the investigation of the role of small EVs in their response to stress. Though relatively few experimental works address this issue to date, the available data indicate that stress conditions would affect the composition of protein cargo of vesicles released by stressed cells, as evidenced by the functional importance of such changes in the context of the response of recipient cells.

Exosomes, new biomarkers in early cancer detection

Exosomes are endosomal-derived vesicles, playing a major role in cell-to-cell communication. Multiple cells secret these vesicles to induce and inhibit different cellular and molecular pathways. Cancer-derived exosomes have been shown to affect development of cancer in different stages and contribute to the recruitment and reprogramming of both proximal and distal tissues. The growing interest in defining the clinical relevance of these nano-sized particles in cancers, has led to the identification of either tissue- or disease-specific exosomal contents, such as nucleic acids, proteins and lipids as a source of new biomarkers which propose the diagnostic potentials of exosomes in early detection of cancers. In this review, we have discussed some aspects of exosomes including their contents, applications and isolation techniques in the field of early cancer detection. Although, exosomes are considered as ideal biomarkers in cancer diagnosis, due to their unique characteristics, there is still a long way in the development of exosome-based assays.

Cancer Exosomes as Conveyors of Stress-Induced Molecules: New Players in the Modulation of NK Cell Response

Natural killer (NK) cells are innate lymphoid cells that play a pivotal role in tumor surveillance. Exosomes are nanovesicles released into the extracellular environment via the endosomal vesicle pathway and represent an important mode of intercellular communication. The ability of anticancer chemotherapy to enhance the immunogenic potential of malignant cells mainly relies on the establishment of the immunogenic cell death (ICD) and the release of damage-associated molecular patterns (DAMPs). Moreover, the activation of the DNA damage response (DDR) and the induction of senescence represent two crucial modalities aimed at promoting the clearance of drug-treated tumor cells by NK cells. Emerging evidence has shown that stress stimuli provoke an increased release of exosome secretion. Remarkably, tumor-derived exosomes (Tex) produced in response to stress carry distinct type of DAMPs that activate innate immune cell populations. Moreover, stress-induced ligands for the activating receptor NKG2D are transported by this class of nanovesicles. Here, we will discuss how Tex interact with NK cells and provide insight into their potential role in response to chemotherapy-induced stress stimuli. The capability of some "danger signals" carried by exosomes that indirectly affect the NK cell activity in the tumor microenvironment will be also addressed.

Hsp70 interactions with membrane lipids regulate cellular functions in health and disease

Beyond guarding the cellular proteome the major stress inducible heat shock protein Hsp70 has been shown to interact with lipids. Non-cytosolic Hsp70 stabilizes membranes during stress challenges and, in pathophysiological states, facilitates endocytosis, counteracts apoptotic mechanisms, sustains survival pathways or represents a signal that can be recognized by the immune system. Disease-coupled lipid-associated functions of Hsp70 may be targeted via distinct subcellular localizations of Hsp70 itself or its specific interacting lipids. With a special focus on interacting lipids, here we discuss localization-dependent roles of the membrane-bound Hsp70 in the context of its therapeutic potential, particularly in cancer and neurodegenerative diseases.