Characterization and proteomic analysis of ovarian cancer-derived exosomes

Pathophysiological Role and Potential Therapeutic Exploitation of Exosomes in Ovarian Cancer

Exosomes are extracellular vesicles involved in several biological and pathological molecules and can carry many bioactive materials to target cells. They work as important mediators of cell-cell communication and play essential roles in many diseases, especially in cancer. Ovarian cancer is one of the most common gynecological malignancies. Most patients are diagnosed at advanced stages involving widespread peritoneal dissemination, resulting in poor prognosis. Emerging evidence has shown that exosomes play vital roles throughout the progression of ovarian cancer. Moreover, the development of engineered exosome-based therapeutic applications— including drug delivery systems, biomolecular targets and immune therapy—has increased drastically. Herein, we review the functional features of exosomes in ovarian cancer progression and the therapeutic application potential of exosomes as novel cancer treatments.

Update on urine as a biomarker in cancer: a necessary review of an old story

Introduction: Cancer causes thousands of deaths worldwide each year. Therefore, monitoring of health status and the early diagnosis of cancer using noninvasive assays, such as the analysis of molecular biomarkers in urine, is essential. However, effective biomarkers for early diagnosis of cancer have not been established in many types of cancer.Areas covered: In this review, we discuss recent findings with regard to the use of urine composition as a biomarker in eleven types of cancer. We also highlight the use of urine biomarkers for improving early diagnosis.Expert opinion: Urinary biomarkers have been applied for clinical application of early diagnosis. The main limitation is a lack of integrated approaches for identification of new biomarkers in most cancer. The utilization of urinary biomarker detection will be promoted by improved detection methods and new data from different types of cancers. With the development of precision medicine, urinary biomarkers will play an increasingly important clinical role. Future early diagnosis would benefit from changes in the utilization of urinary biomarkers.

Extracellular vesicle-associated proteins as potential biomarkers

Every cell in the body secretes extracellular vesicles (EVs) possibly as cellular signaling components and these cell-derivatives can be found in multiple numbers in biological fluids. EVs have in the scientific field received great attention in relation to pathophysiology and disease diagnostics. Altered protein expressions associated with circulating EVs in diseased individuals can serve as biomarkers for different disease states. This capacity paves the way for non-invasive screening tools and early diagnostic markers. However, no isolation method of EVs has been acknowledged as the "golden standard," thus reproducibility of the studies remains inadequate. Increasing interest in EV proteins as disease biomarkers could give rise to more scientific knowledge with diagnostic applicability. In this chapter, studies of proteins believed to be associated with EVs within cancer, autoimmunity, metabolic and neurodegenerative diseases have been outlined.

Intracellular Chloride Channels: Novel Biomarkers in Diseases

Ion channels are integral membrane proteins present on the plasma membrane as well as intracellular membranes. In the human genome, there are more than 400 known genes encoding ion channel proteins. Ion channels are known to regulate several cellular, organellar, and physiological processes. Any mutation or disruption in their function can result in pathological disorders, both common or rare. Ion channels present on the plasma membrane are widely acknowledged for their role in various biological processes, but in recent years, several studies have pointed out the importance of ion channels located in intracellular organelles. However, ion channels located in intracellular organelles are not well-understood in the context of physiological conditions, such as the generation of cellular excitability and ionic homeostasis. Due to the lack of information regarding their molecular identity and technical limitations of studying them, intracellular organelle ion channels have thus far been overlooked as potential therapeutic targets. In this review, we focus on a novel class of intracellular organelle ion channels, Chloride Intracellular Ion Channels (CLICs), mainly documented for their role in cardiovascular, neurophysiology, and tumor biology. CLICs have a single transmembrane domain, and in cells, they exist in cytosolic as well as membranous forms. They are predominantly present in intracellular organelles and have recently been shown to be localized to cardiomyocyte mitochondria as well as exosomes. In fact, a member of this family, CLIC5, is the first mitochondrial chloride channel to be identified on the molecular level in the inner mitochondrial membrane, while another member, CLIC4, is located predominantly in the outer mitochondrial membrane. In this review, we discuss this unique class of intracellular chloride channels, their role in pathologies, such as cardiovascular, cancer, and neurodegenerative diseases, and the recent developments concerning their usage as theraputic targets.

Proteomic and lipidomic analysis of exosomes derived from ovarian cancer cells and ovarian surface epithelial cells

BACKGROUND

The limitation of current biomarker of early stage ovarian cancer and the anatomical location of ovarian (depths of the pelvic) make ovarian cancer difficult to be detected in early stage. Growing evidence shows exosomes as key information transmitters, it carried molecules, such as miRNAs, proteins, lipids, double-stranded DNA have been reported as promising biomarkers in many diseases. However, little is known about the protein and lipid composition of ovarian cancer.

METHODS

Here, we report proteomic and lipidomic analysis of exosomes derived from ovarian cancer cells (SKOV-3) and ovarian surface epithelial cells (HOSEPiC).

RESULTS

A total of 1433 proteins and 1227 lipid species were identified from two cell line derived exosomes. Several lipid species and proteins significantly differ in SKOV-3 derived exosomes compared to those from HOSEPiC. For example, we noted that ChE and ZyE species were in general more abundant in exosomes from SKOV-3 than from HOSEPiC; Collagen type V alpha 2 chain (COL5A2) and lipoprotein lipase (LPL) were significantly higher in SKOV-3 derived exosomes than HOSEpic (p < 0.05).

CONCLUSIONS

Our research indicates the promising role of exosomal proteins and lipids in the early diagnosis of ovarian cancer.

Human Breast Milk-Derived Extracellular Vesicles in the Protection Against Experimental Necrotizing Enterocolitis

PURPOSE

Necrotizing enterocolitis (NEC) is a leading cause of death in premature infants. Breast feeding decreases the incidence of NEC but, even with aggressive promotion of nursing in Neonatal Intensive Care Units, morbidity and mortality remain high. Previous studies from our laboratory have demonstrated that extracellular vesicles (EVs) purified from mouse and rat stem cells can protect the intestines from NEC. The aim of this study was to determine whether human breast milk (BM)-derived EVs could prevent NEC.

METHODS

EVs were purified from human donor breast milk. NEC was induced in premature rat pups by exposure to asphyxia/hypothermia/hypercaloric feeds. Pups were randomized to: (1) breast fed, no injury, (2) NEC, (3) NEC + BM-derived EVs once intraperitoneally (IP), (4) NEC + BM-derived EVs enterally (PO) with each feed. Intestinal tracts were examined for histologic damage. Additionally, the effect of BM-derived EVs on intestinal epithelial cells (IEC) subjected to hypoxia/reoxygenation injury in vitro was examined.

RESULTS

NEC incidence was 0% in breast-fed pups and 62% in pups subjected to NEC. IP administration of BM-derived EVs decreased NEC incidence to 29% and enteral administration further decreased NEC incidence to 11.9%. (p < 0.05). BM-derived EVs significantly increased cell proliferation and decreased apoptosis in IEC in vitro.

CONCLUSION

Breast milk-derived EVs delivered either IP or enterally significantly decrease the incidence and severity of experimental NEC, protect IEC from injury in vitro, and may represent an innovative therapeutic option for NEC in the future.

TYPE OF STUDY

Basic science study.

LEVEL OF EVIDENCE

N/A.

Extracellular Vesicles: Recent Developments in Technology and Perspectives for Cancer Liquid Biopsy

Extracellular micro- and nanoscale membrane vesicles produced by different cells progressively attract the attention of the scientific community. They function as mediators of intercellular communication and transport genetic material and signaling molecules between the cells. In the context of keeping homeostasis, the extracellular vesicles contribute to the regulation of various systemic and local processes. Vesicles released by the tumor and activated stromal cells exhibit multiple functions including support of tumor growth, preparation of the pre-metastatic niches, and immune suppression. Considerable progress has been made regarding the criteria of classification of the vesicles according to their origin, content, and function: Exosomes, microvesicles, also referred to as microparticles or ectosomes, and large oncosomes were defined as actively released vesicles. Additionally, apoptotic bodies represented by a highly heterogeneous population of particles produced during apoptosis, the programmed cell death, should be considered. Because the majority of isolation techniques do not allow the separation of different types of vesicles, a joined term "extracellular vesicles" (EVs) was recommended by the ISEV community for the definition of vesicles isolated from either the cell culture supernatants or the body fluids. Because EV content reflects the content of the cell of origin, multiple studies on EVs from body fluids in the context of cancer diagnosis, prediction, and prognosis were performed, actively supporting their high potential as a biomarker source. Here, we review the leading achievements in EV analysis from body fluids, defined as EV-based liquid biopsy, and provide an overview of the main EV constituents: EV surface proteins, intravesicular soluble proteins, EV RNA including mRNA and miRNA, and EV DNA as potential biomarkers. Furthermore, we discuss recent developments in technology for quantitative EV analysis in the clinical setting and future perspectives toward miniaturized high-precision liquid biopsy approaches.

Neuronal-derived extracellular vesicles are enriched in the brain and serum of HIV-1 transgenic rats

Despite the efficacy of combination antiretroviral therapy (ART) in controlling human immunodeficiency virus (HIV-1) replication, cytotoxic viral proteins such as HIV-1 transactivator of transcription (Tat) persist in tissues such as the brain. Although HIV-1 does not infect neuronal cells, it is susceptible to viral Tat protein-mediated toxicity, leading to neuroinflammation that underlies HIV-associated neurocognitive disorders (HAND). Given the role of extracellular vesicles (EVs) in both cellular homoeostasis and under pathological conditions, we sought to investigate the alterations in the quantity of neuronal-derived EVs in the brain - as defined by the presence of cell adhesion molecule L1 (L1CAM) and to evaluate the presence of L1CAM⁺ EVs in the peripheral circulation of HIV-1 transgenic (HIV-1 Tg) rats. The primary goal of this study was to investigate the effect of long-term exposure of HIV-1 viral proteins on the release of neuronal EVs in the brain and their transfer in the systemic compartment. Brain and serum EVs were isolated from both wild type and HIV-1 Tg rats using differential ultracentrifugation with further purification using the Optiprep gradient method. The subpopulation of neuronal EVs was further enriched using immunoprecipitation. The current findings demonstrated increased presence of L1CAM⁺ neuronal-derived EVs both in the brain and serum of HIV-1 Tg rats.

Implications of exosomes as diagnostic and therapeutic strategies in cancer

Exosomes offer a new perspective on the biology of cancer with both diagnostic and therapeutic concepts. Due to the cell-to-cell association, exosomes are involved in the progression, metastasis, and therapeutic efficacy of the tumor. They can be isolated from blood and other body fluids to determine the disease progression in the body, including cancer growth. In addition to being reservoirs of biochemical markers of cancer, exomes can be designed to restore tumor immunity. Tumor exosomes interact with different cells in the tumor microenvironment to confer beneficial modulations, responsible for stromal activity, angiogenesis, increased vascular permeability, and immune evasion. Exosomes also contribute to the metastasis with the aim of epithelial transmission to the mesenchyme and the formation of premetastatic niches. Moreover, exosomes protect cells against the cytotoxic effects of chemotherapeutic drugs and prevent the transmission of chemotherapy resistance to adjacent cells. Therefore, exosomes are essential for many fatal cancer agents, and understanding their origins and role in cancer is important. In this article, we attempted to clarify the potential of exosomes for the application in cancer diagnosis and therapy.

Low level electricity increases the secretion of extracellular vesicles from cultured cells

Exosomes, a type of extracellular vesicles, can be collected from the conditioned medium of cultured cells, and are expected to be used in disease therapy and drug delivery systems. However, since the yield of exosomes from conditioned medium is generally low, investigations to develop new methods to increase exosome secretion and to elucidate the secretion mechanism have been performed. Our previous studies demonstrated that activation of intracellular signaling including Rho GTPase and subsequent endocytosis of extraneous molecules in cells could be induced by low level electricity (0.3–0.5 mA/cm²). Since exosomes are produced in the process of endocytosis and secreted by exocytosis via certain signaling pathways, we hypothesized that low level electric treatment (ET) would increase exosome secretion from cultured cells via intracellular signaling activation. In the present study, the influence of ET (0.34 mA/cm²) on extracellular vesicle (EV) secretion from cultured cells was examined by using murine melanoma and murine fibroblast cells. The results showed that the number of EV particles collected by ultracentrifugation was remarkably increased by ET in both cell lines without cellular toxicity or changes in the particle distribution. Also, protein amounts of the collected EVs were significantly increased in both cells by ET without alteration of expression of representative exosome marker proteins. Moreover, in both cells, the ratio of particle numbers to protein amount was not significantly changed by ET. Rho GTPase inhibition significantly suppressed ET-mediated increase of EV secretion in murine melanoma, indicating that Rho GTPase activation could be involved in ET-mediated EV secretion in the cell. Additionally, there were almost no differences in uptake of each EV into each donor cell regardless of whether the cells had been exposed to ET for EV collection. Taken together, these results suggest that ET could increase EV secretion from both cancer and normal cells without apparent changes in EV quality.

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Low level electric treatment (ET; 0.34 mA/cm²) increased exosome yield from cells.

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The number of exosome particles was increased by ET without distribution changes.

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ET increased protein amounts of the collected exosomes from conditioned media.

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ET did not induce cellular toxicity and change in exosomal marker protein expression.

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ET-mediated increase of exosome secretion occurred in both cancer and normal cells.

Ovarian cancer circulating extracelluar vesicles promote coagulation and have a potential in diagnosis: an iTRAQ based proteomic analysis

Background

Circulating extracelluar vesicles (EVs) in epithelial ovarian cancer (EOC) patients emanate from multiple cells. These EVs are emerging as a new type of biomarker as they can be obtained by non-invasive approaches. The aim of this study was to investigate circulating EVs from EOC patients and healthy women to evaluate their biological function and potential as diagnostic biomarkers.

Methods

A quantitative proteomic analysis (iTRAQ) was applied and performed on 10 EOC patients with advanced stage (stage III–IV) and 10 controls. Twenty EOC patients and 20 controls were applied for validation. The candidate proteins were further validated in another 40-paired cohort to investigate their biomarker potential. Coagulation cascades activation was accessed by determining Factor X activity.

Results

Compared with controls, 200 proteins were upregulated and 208 proteins were downregulated in the EOC group. The most significantly involved pathway is complement and coagulation cascades. ApoE multiplexed with EpCAM, plg, serpinC1 and C1q provide optimal diagnostic information for EOC with AUC = 0.913 (95% confidence interval (CI) =0.848–0.957, p < 0.0001). Level of activated Factor X was significantly higher in EOC group than control (5.35 ± 0.14 vs. 3.69 ± 0.29, p < 0.0001).

Conclusions

Our study supports the concept of circulating EVs as a tool for non-invasive diagnosis of ovarian cancer. EVs also play pivotal roles in coagulation process, implying the inherent mechanism of generation of thrombus which often occurred in ovarian cancer patients at late stages.

Beyond tumor mutational burden: potential and limitations in using exosomes to predict response to immunotherapy

Introduction: Immune checkpoint blockade (ICB) has ushered in a new era of cancer therapeutics. The standard for determining which patients might benefit from ICB-based therapies is through the assessment of tumor mutational burden using formalin-fixed paraffin-embedded (FFPE) tumor tissue samples; however, this strategy is imperfect. The discovery of exosomal PD-L1 has placed these nano-vesicles to the forefront of immunotherapy biomarker development. Exosomes and other extracellular vesicles contain proteins and nucleic acids specific to their cell of origin and their production is increased in disease state such as cancer and can be isolated from most types of liquid biopsy. Given this opportunity, a large-scale bioengineering effort has centered on developing technologies capable of isolating distinct subsets of exosomes and interrogating their content for biomarker discovery.Areas covered: This review investigates the current state of small extracellular vesicles (sEVs), focusing on exosomes, as they relate to biomarkers of IBC. We will discuss technologies being developed to both capture and evaluate exosomal cargo and as some of the challenges they face.Expert opinion: The advancement of microfluidic technologies, along with rapidly evolving methodologies in RNAseq and proteomics, are making the potential of utilizing exosomes as prognostic and diagnostic biomarkers of ICB into a likely reality.

Exosomes: New insights into cancer mechanisms

Exosomes are mobile extracellular vesicles with a diameter 40 to 150 nm. They play a critical role in several processes such as the development of cancers, intercellular signaling, drug resistance mechanisms, and cell-to-cell communication by fusion onto the cell membrane of recipient cells. These vesicles contain endogenous proteins and both noncoding and coding RNAs (microRNA and messenger RNAs) that can be delivered to various types of cells. Furthermore, exosomes exist in body fluids such as plasma, cerebrospinal fluid, and urine. Therefore, they could be used as a novel carrier to deliver therapeutic nucleic-acid drugs for cancer therapy. It was recently documented that, hypoxia promotes exosomes secretion in different tumor types leading to the activation of vascular cells and angiogenesis. Cancer cell-derived exosomes (CCEs) have been used as prognostic and diagnostic markers in many types of cancers because exosomes are stable at 4°C and -70°C. CCEs have many functional roles in tumorigenesis, metastasis, and invasion. Consequently, this review presents the data about the therapeutic application of exosomes and the role of CCEs in cancer invasion, drug resistance, and metastasis.

Wnt Signaling in Ovarian Cancer Stemness, EMT, and Therapy Resistance

Ovarian cancers represent the deadliest among gynecologic malignancies and are characterized by a hierarchical structure with cancer stem cells (CSCs) endowed with self-renewal and the capacity to differentiate. The Wnt/β-catenin signaling pathway, known to regulate stemness in a broad spectrum of stem cell niches including the ovary, is thought to play an important role in ovarian cancer. Importantly, Wnt activity was shown to correlate with grade, epithelial to mesenchymal transition, chemotherapy resistance, and poor prognosis in ovarian cancer. This review will discuss the current knowledge of the role of Wnt signaling in ovarian cancer stemness, epithelial to mesenchymal transition (EMT), and therapy resistance. In addition, the alleged role of exosomes in the paracrine activation of Wnt signaling and pre-metastatic niche formation will be reviewed. Finally, novel potential treatment options based on Wnt inhibition will be highlighted.

The effects of ovarian cancer cell-derived exosomes on vascular endothelial growth factor expression in endothelial cells

Ovarian carcinoma is considered as a major clinical challenge worldwide. Exosomes, nano-sized intraluminal vesicles of multivesicular bodies, are secreted by most types of cells and play an important role in intercellular communication. Cancer cell-derived exosomes can develop cancer progression and metastasis by manipulating the local and distant biological environments. Angiogenesis is an important contributor to tumor progression. Vascular endothelial growth factor (VEGF) is the most potent pro-angiogenic protein and induces proliferation, sprouting, and vessel formation by endothelial cells. In this study, exosomes derived from ovarian epithelial cancer cells OVACAR-3 (exo-OVCAR-3) were successfully isolated and characterized by scanning electron microscopy in terms of size and morphology. Cellular internalization of exosomes labeled with PKH fluorescent dye was monitored by a fluorescence microscope. Our results elucidated that exosomes treatment (100 µg/ml) had a promoting effect on VEGF expression and secretion in endothelial cells. Furthermore, we demonstrated that exo-OVCAR-3 caused an increase in the proliferation and migration rate of endothelial cells. It seems that inducing VEGF by exo-OVCAR-3 can influence the vascular behavior of endothelial cells in vitro.

Proteomic Profiling of Rhabdomyosarcoma-Derived Exosomes Yield Insights into Their Functional Role in Paracrine Signaling

Exosomes are important intercellular communication vehicles, secreted into body fluids by multiple cell types, including tumor cells. They have been demonstrated to contribute to the metastatic progression of tumor cells through paracrine signaling. Tumor exosomes contain intact and functional proteins, mRNA and miRNA that may alter the cellular environment to favor tumor growth. We evaluated the protein cargo of exosomes derived from the childhood tumor rhabdomyosarcoma (RMS) and the molecular pathways they are implicated in to decipher their role in the progression of this aggressive disease. We conducted a mass spectrometry analysis of exosome content isolated from five RMS cell lines: three of embryonal RMS (ERMS) and two of alveolar RMS (ARMS) histology and verified results by multiple reaction monitoring and western blot analyses. Results revealed 161 common proteins in ERMS-derived exosomes and 122 common proteins in ARMS-derived exosomes, of which 81 proteins were common to both subtypes. Using both PANTHER gene classification and Pathway Studio software, we assessed the perturbed biological processes and altered pathways in which the exosomal proteins are involved. The 81 commonly expressed proteins included those involved in "cell-signaling," "cell-movement," and "cancer." Pathways engaging the identified proteins revealed 37 common pathways including "integrin signaling pathway," "inflammation mediated by chemokine and cytokine signaling pathway," and "angiogenesis." Finally, a comparison of exosomal proteins of RMS cells with publicly available datasets from other cancer cells revealed that 36 proteins are specific and endogenous to the RMS-exosomes. Taken together, our results reveal that RMS-derived exosomes carry a protein cargo that contributes to conserved cellular signaling networks across multiple cell lines, and we also identify RMS exosome-specific proteins that should be further evaluated as possible novel biomarkers for this tumor.

Exosomes: Revisiting their role as "garbage bags"

In recent years, the term "extracellular vesicle" (EV) has been used to define different types of vesicles released by various cells. It includes plasma membrane-derived vesicles (ectosomes/microvesicles) and endosome-derived vesicles (exosomes). Although it remains difficult to evaluate the compartment of origin of the two kinds of vesicles once released, it is critical to discriminate these vesicles because their mode of biogenesis is probably directly related to their physiologic function and/or to the physio-pathologic state of the producing cell. The purpose of this review is to specifically consider exosome secretion and its consequences in terms of a material loss for producing cells, rather than on the effects of exosomes once they are taken up by recipient cells. I especially describe one putative basic function of exosomes, that is, to convey material out of cells for off-site degradation by recipient cells. As illustrated by some examples, these components could be evacuated from cells for various reasons, for example, to promote "differentiation" or enhance homeostatic responses. This basic function might explain why so many diseases have made use of the exosomal pathway during pathogenesis.

Myoferlin, a multifunctional protein in normal cells, has novel and key roles in various cancers

Myoferlin, a protein of the ferlin family, has seven C2 domains and exhibits activity in some cells, including myoblasts and endothelial cells. Recently, myoferlin was identified as a promising target and biomarker in non-small-cell lung cancer, breast cancer, pancreatic adenocarcinoma, hepatocellular carcinoma, colon cancer, melanoma, oropharyngeal squamous cell carcinoma, head and neck squamous cell carcinoma, clear cell renal cell carcinoma and endometrioid carcinoma. This evidence indicated that myoferlin was involved in the proliferation, invasion and migration of tumour cells, the mechanism of which mainly included promoting angiogenesis, vasculogenic mimicry, energy metabolism reprogramming, epithelial-mesenchymal transition and modulating exosomes. The roles of myoferlin in both normal cells and cancer cells are of great significance to provide novel and efficient methods of tumour treatment. In this review, we summarize recent studies and findings of myoferlin and suggest that myoferlin is a novel potential candidate for clinical diagnosis and targeted cancer therapy.

Ferlin Overview: From Membrane to Cancer Biology

In mammal myocytes, endothelial cells and inner ear cells, ferlins are proteins involved in membrane processes such as fusion, recycling, endo- and exocytosis. They harbour several C2 domains allowing their interaction with phospholipids. The expression of several Ferlin genes was described as altered in several tumoural tissues. Intriguingly, beyond a simple alteration, myoferlin, otoferlin and Fer1L4 expressions were negatively correlated with patient survival in some cancer types. Therefore, it can be assumed that membrane biology is of extreme importance for cell survival and signalling, making Ferlin proteins core machinery indispensable for cancer cell adaptation to hostile environments. The evidences suggest that myoferlin, when overexpressed, enhances cancer cell proliferation, migration and metabolism by affecting various aspects of membrane biology. Targeting myoferlin using pharmacological compounds, gene transfer technology, or interfering RNA is now considered as an emerging therapeutic strategy.

Distinct mechanisms of microRNA sorting into cancer cell-derived extracellular vesicle subtypes

Extracellular vesicles (EVs) encompass a variety of vesicles secreted into the extracellular space. EVs have been implicated in promoting tumor metastasis, but the molecular composition of tumor-derived EV sub-types and the mechanisms by which molecules are sorted into EVs remain mostly unknown. We report the separation of two small EV sub-populations from a metastatic breast cancer cell line, with biochemical features consistent with different sub-cellular origins. These EV sub-types use different mechanisms of miRNA sorting (selective and non-selective), suggesting that sorting occurs via fundamentally distinct processes, possibly dependent on EV origin. Using biochemical and genetic tools, we identified the Lupus La protein as mediating sorting of selectively packaged miRNAs. We found that two motifs embedded in miR-122 are responsible for high-affinity binding to Lupus La and sorting into vesicles formed in a cell-free reaction. Thus, tumor cells can simultaneously deploy multiple EV species using distinct sorting mechanisms that may enable diverse functions in normal and cancer biology.

Exosomes promote pre-metastatic niche formation in ovarian cancer

Ovarian cancer is one of the most common gynecological malignancies. Upon initial diagnosis, the majority of patients present with widespread metastatic growth within the peritoneal cavity. This metastatic growth occurs in stages, with the formation of a pre-metastatic niche occurring prior to macroscopic tumor cell invasion. Exosomes released by the primary ovarian tumor are small extracellular vesicles which prepare the distant tumor microenvironment for accelerated metastatic invasion. They regulate intercellular communication between tumor cells and normal stroma, cancer-associated fibroblasts, and local immune cells within the tumor microenvironment. In this review, we highlight the emerging roles of ovarian cancer exosomes as coordinators of pre-metastatic niche formation, biomarkers amenable to liquid biopsy, and targets of chemotherapy.

Serum anti-EIF3A autoantibody as a potential diagnostic marker for hepatocellular carcinoma

Tumor-associated autoantibodies are promising diagnostic biomarkers for early detection of tumors. We have screened a novel tumor-associated autoantibody in hepatocellular carcinoma (HCC) model mice. Its target antigen was identified as eukaryotic translation initiation factor 3 subunit A (EIF3A) by proteomic analysis, and the elevated expression of EIF3A in HCC tissues of tumor model mice as well as human patients was shown. Also, its existence in tumor-derived exosomes was revealed, which seem to be the cause of tumor-associated autoantibody production. To use serum anti-EIF3A autoantibody as biomarker, ELISA detecting anti-EIF3A autoantibody in human serum was performed using autoantibody-specific epitope. For the sensitive detection of serum autoantibodies its specific conformational epitopes were screened from the random cyclic peptide library, and a streptavidin antigen displaying anti-EIF3A autoantibody-specific epitope, XC90p2(-CPVRSGFPC-), was used as capture antigen. It distinguished patients with HCC (n = 102) from healthy controls (n = 0285) with a sensitivity of 79.4% and specificity of 83.5% (AUC = 0.87). Also, by simultaneously detecting with other HCC biomarkers, including alpha-fetoprotein, HCC diagnostic sensitivity improved from 79.4% to 85%. Collectively, we suggest that serum anti-EIF3A autoantibody is a useful biomarker for the diagnosis of HCC and the combinational detection of related biomarkers can enhance the accuracy of the cancer diagnosis.

Isolation and quantitation of exosomes isolated from human plasma via hydrophobic interaction chromatography using a polyester, capillary-channeled polymer fiber phase

Exosomes are one class of extracellular vesicles (30-150 nm diameter) that are secreted by cells. These small vesicles hold a great deal of promise in disease diagnostics, as they display the same protein biomarkers as their originating cell. On a cellular level, exosomes are attributed to playing a key role in intercellular communication, and may eventually be exploited for targeted drug delivery. In order for exosomes to become useful in disease diagnostics, and as burgeoning drug delivery platforms, they must be isolated efficiently and effectively without compromising their structure. Plasma from peripheral blood is an excellent source of exosomes, as it is easily collected and the process does not normally cause undue discomfort to the patient. Unfortunately, blood plasma content is complex, containing abundant amounts of soluble proteins and aggregates, making exosomes extremely difficult to isolate in high purity from plasma. Most current exosome isolation methods have practical challenges including being too time-consuming and labor intensive, destructive to the exosomes, or too costly for use in clinical settings. To this end, this study examines the use of poly(ethylene terephthalate) (PET) capillary-channeled polymer (C-CP) fibers in a hydrophobic interaction chromatography (HIC) protocol to isolate exosomes from a human plasma sample. Initial results demonstrate the ability to isolate exosomes with comparable yields and size distributions and on a much faster time scale when compared to traditional isolation methods, while also alleviating concomitant proteins and other impurities. As a demonstration of the potential quantitative utility of the approach, a linear response (particles injected on-column vs peak area) using a commercial exosome standard was established using a standard UV absorbance detector. Based on the calibration function, the concentration of the original human plasma sample was determined and subsequently confirmed by NTA measurement. The potential for scalable separations covering sub-milliliter spin-down solid phase extraction tips to the preparative scale is anticipated.

The Proteome of Pancreatic Cancer-Derived Exosomes Reveals Signatures Rich in Key Signaling Pathways

Exosomes are membrane-bound vesicles that traffic small molecular cargos. These cargos participate in cell-cell communication and contribute to the pathogenesis of many disease including cancer. How these mechanisms contribute to communication within the pancreatic adenocarcinoma (PDAC) microenvironment and how they contribute to PDAC biology are poorly understood. Performed in this study are comprehensive, quantitative comparisons of the proteomes of three PDAC cell lines to those of the exosomes they produce. Approximately 35% of whole cell proteins sort into exosomes. Analysis of composition of microbiomes (ANCOM) determined a cluster of 98 enriched pancreatic cancer exosome core proteins (ePC-ECPs). Further, these proteins are predicted by ingenuity pathway analysis (IPA) as actively involved in signaling pathways regulating cell death and survival, cellular movement, and cell-to-cell signaling and interaction in particular (top three p-value significant pathways). Significant enrichment of canonical pathways of acute phase response signaling (inflammatory response signaling pathways) and FXR and RXR activation in biosynthetic pathways are also predicted; 97 ePC-ECPs are associated with cancer and among them, 34 are specifically associated with PDAC. In conclusion, exosomes from PDAC are enriched with cancer-associated signaling proteins. Further assessment of these proteins as PDAC biomarkers or therapeutic targets is warranted.

Characterization of mRNA profiles of the exosome-like vesicles in porcine follicular fluid

Extracellular vesicles such as exosomes contain several types of transcripts, including mRNAs and micro RNAs (miRNAs), and have emerged as important mediators of cell-to-cell communication. Exosome-like vesicles were identified in the ovarian follicles of several mammalian species. Although the miRNA contents have been extensively characterized, the detailed investigation of their mRNA profiles is lacking. Here, we characterize the mRNA profiles of exosome-like vesicles in ovarian follicles in a pig model. The mRNA contents of the exosome-like vesicles isolated from porcine follicular fluid were analyzed and compared with those from mural granulosa cells (MGCs) using the Illumina HiSeq platform. Bioinformatics studies suggested that the exosomal mRNAs are enriched in those encoding proteins involved in metabolic, phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) -protein kinase B (AKT), and mitogen-activated protein kinase (MAPK) pathways. While the mRNA profile of the exosome-like vesicles resembled that of MGCs, the vesicles contained mRNAs barely detectable in MGCs. Thus, while the majority of the vesicles are likely to be secreted from MGCs, some may originate from other cell types, including theca cells and oocytes, as well as the cells of non-ovarian organs/tissues. Therefore, the mRNA profiles unveiled several novel characteristics of the exosome-like vesicles in ovarian follicles.

Exosomes from Macrophages Exposed to Apoptotic Breast Cancer Cells Promote Breast Cancer Proliferation and Metastasis

Exosomes have recently become the subject of increasing research interest. Interactions between tumor and host cells via exosomes play crucial roles in the initiation, progression and invasiveness of breast cancer. In our study, we used exosomes isolated from a co-culture model of THP-1-derived macrophages exposed to apoptotic MCF-7 or MDA-MB-231 breast cancer cell line cells to investigate their effects on naïve MCF-7 or MDA-MB-231 cells in vitro and in vivo. This post-chemotherapy tumor microenvironment model allowed us to explore possible mechanisms that explain increased proliferation and metastasis of breast cancer seen in some patients. Our results suggest that while exosomes derived from macrophages normally inhibit proliferation and metastasis of MCF-7 or MDA-MB-231 cells, exposure of macrophages to breast cancer cells that have experienced chemotherapy are modified them to promote these processes. Exosomes from macrophages exposed to apoptotic cancer cells have increased amounts of IL-6 that increases the phosphorylation of STAT3, which likely explains the increased transcription of STAT3 target genes such as CyclinD1, MMP2 and MMP9. These observations suggest that the inhibition of exosome secretion and STAT3 signaling pathway activation might suppress the growth and metastasis of malignant tumors, and provide new targets for therapeutic treatment of malignant tumors after chemotherapy.

Liquid biopsy in ovarian cancer: recent advances in circulating extracellular vesicle detection for early diagnosis and monitoring progression

The current biomarkers available in the clinic are not enough for early diagnosis or for monitoring disease progression of ovarian cancer. Liquid biopsy is a minimally invasive test and has the advantage of early diagnosis and real-time monitoring of treatment response. Although significant progress has been made in the usage of circulating tumor cells and cell-free DNA for ovarian cancer diagnosis, their potential for early detection or monitoring progression remains elusive. Extracellular vesicles (EVs) are a heterogeneous group of lipid membranous particles released from almost all cell types. EVs contain proteins, mRNA, DNA fragments, non-coding RNAs, and lipids and play a critical role in intercellular communication. Emerging evidence suggests that EVs have crucial roles in cancer development and metastasis, thus holding promise for liquid biopsy-based biomarker discovery for ovarian cancer diagnosis. In this review, we discuss the advantages of EV-based liquid biopsy, summarize the protein biomarkers identified from EVs in ovarian cancer, and highlight the utility of new technologies recently developed for EV detection with an emphasis on their use for diagnosing ovarian cancer, monitoring cancer progression, and developing personalized medicine.

Mass spectrometry-based proteome profiling of extracellular vesicles and their roles in cancer biology

Over the past three decades, extracellular vesicles (EVs) have arisen as important mediators of intercellular communication that are involved in the transmission of biological signals between cells to regulate various biological processes. EVs are largely responsible for intercellular communication through the delivery of bioactive molecules, such as proteins, messenger RNAs (mRNAs), microRNAs (miRNAs), DNAs, lipids, and metabolites. EVs released from cancer cells play a significant role in signal transduction between cancer cells and the surrounding cells, which contributes to the formation of tumors and metastasis in the tumor microenvironment. In addition, EVs released from cancer cells migrate to blood vessels and flow into various biological fluids, including blood and urine. EVs and EV-loaded functional cargoes, including proteins and miRNAs, found in these biological fluids are important biomarkers for cancer diagnosis. Therefore, EV proteomics greatly contributes to the understanding of carcinogenesis and tumor progression and is critical for the development of biomarkers for the early diagnosis of cancer. To explore the potential use of EVs as a gateway to understanding cancer biology and to develop cancer biomarkers, we discuss the mass spectrometric identification and characterization of EV proteins from different cancers. Information provided in this review may help in understanding recent progress regarding EV biology and the potential roles of EVs as new noninvasive biomarkers and therapeutic targets.

Tumor cells release tiny membrane-encapsulated packages known as extracellular vesicles containing proteins which could serve as prognostic disease biomarkers or therapeutic targets. Kwang Pyo Kim and colleagues from Kyung Hee University in Yongin, South Korea, review the use of mass spectrometry to profile the diversity of proteins found in these tumor-derived packages. The proteins found in these vesicles help mediate communication between cancer cells and their surrounding tissues. Different tumor types share many of these proteins in common, but there are differences in the protein profile related to cancer-associated biological processes such as metastasis and cell proliferation. Tests based on the proteins contained in these vesicles could help clinicians better identify, diagnose and treat specific cancers, although large, multicenter studies are needed to validate such strategies.

Proteomics profiling of plasma exosomes in epithelial ovarian cancer: A potential role in the coagulation cascade, diagnosis and prognosis

Ovarian cancer remains the most lethal type of cancer among all gynecological malignancies. The majority of patients are diagnosed with ovarian cancer at the late stages of the disease. Therefore, there exists an imperative need for the development of early ovarian cancer diagnostic techniques. Exosomes, secreted by various cell types, play pivotal roles in intercellular communication, which emerge as promising diagnostic and prognostic biomarkers for ovarian cancer. In this study, we present for the first time, at least to the best of our knowledge, the proteomics profiling of exosomes derived from the plasma of patients with ovarian cancer via liquid chromatography tandem mass spectrometry (LC-MS/MS) with tandem mass tagging (TMT). The exosomes enriched from patient plasma samples were characterized by nanoparticle tracking analysis (NTA), dynamic light scattering (DLS), transmission electron microscopy (TEM) and western blot analysis. The size of the plasma exosomes fell into the range of 30 to 100 nm in diameter. The exosomal marker proteins, CD81 and TSG101, were clearly stained in the exosome samples; however, there was no staining for the endoplasmic reticulum protein, calnexin. A total of 294 proteins were identified with all exosome samples. Among these, 225 proteins were detected in both the cancerous and non-cancerous samples. Apart from universal exosomal proteins, exosomes derived from ovarian cancer patient plasma also contained tumor-specific proteins relevant to tumorigenesis and metastasis, particularly in epithelial ovarian carcinoma (EOC). Patients with EOC often suffer from coagulation dysfunction. The function of exosomes in coagulation was also examined. Several genes relevant to the coagulation cascade were screened out as promising diagnostic and prognostic factors that may play important roles in ovarian cancer progression and metastasis. On the whole, in this study, we successfully isolated and purified exosomes from plasma of patients with EOC, and identified a potential role of these exosomes in the coagulation cascade, as well as in the diagnosis and prognosis of patients. differentially expressed genes, functional enrichment analysis, protein-protein interaction, diagnostic and prognostic biomarkers

Golgi protein 73 and its diagnostic value in liver diseases

Golgi protein 73 (GP73, also referred to as Golph 2) with 400 amino acids is a 73 kDa transmembrane glycoprotein typically found in the cis-Golg complex. It is primarily expressed in epithelial cells, which has been found upregulated in hepatocytes in patients suffering from both viral and non-viral liver diseases. GP73 has drawn increasing attention for its potential application in the diagnosis of liver diseases such as hepatitis, liver cirrhosis and liver cancer. Herein, we reviewed the discovery history of GP73 and summarized studies by many groups around the world, aiming at understanding its structure, expression, function, detection methods and the relationship between GP73 and liver diseases in various settings.

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.

Biology, Pathophysiological Role, and Clinical Implications of Exosomes: A Critical Appraisal

Exosomes are membrane-enclosed entities of endocytic origin, which are generated during the fusion of multivesicular bodies (MVBs) and plasma membranes. Exosomes are released into the extracellular milieu or body fluids; this process was reported for mesenchymal, epithelial, endothelial, and different immune cells (B-cells and dendritic cells), and was reported to be correlated with normal physiological processes. The compositions and abundances of exosomes depend on their tissue origins and cell types. Exosomes range in size between 30 and 100 nm, and shuttle nucleic acids (DNA, messenger RNAs (mRNAs), microRNAs), proteins, and lipids between donor and target cells. Pathogenic microorganisms also secrete exosomes that modulate the host immune system and influence the fate of infections. Such immune-modulatory effect of exosomes can serve as a diagnostic biomarker of disease. On the other hand, the antigen-presenting and immune-stimulatory properties of exosomes enable them to trigger anti-tumor responses, and exosome release from cancerous cells suggests they contribute to the recruitment and reconstitution of components of tumor microenvironments. Furthermore, their modulation of physiological and pathological processes suggests they contribute to the developmental program, infections, and human diseases. Despite significant advances, our understanding of exosomes is far from complete, particularly regarding our understanding of the molecular mechanisms that subserve exosome formation, cargo packaging, and exosome release in different cellular backgrounds. The present study presents diverse biological aspects of exosomes, and highlights their diagnostic and therapeutic potentials.

Exosomes of malignant tumors: prospects of omiсs diagnostics

The main problems in the diagnostics and treatment of malignant tumors are early detection of the disease, prediction of the course of the disease and response to therapy. The solution may be associated with identification of biomarkers secreted by tumor cells within extracellular vesicles, known as exosomes. The study of exosome proteins attracts special attention, because their molecular composition can have information about tumor identity, and also represent a set of signaling molecules that regulate the processes of tumor progression and growth. In addition, the analysis of exosomes secreted into the extracellular space corresponds to the promising concept of a liquid biopsy. In this review, we have summarized the current experience in the molecular study of exosomes in various types of malignant tumors, including colorectal cancer, lung cancer, ovaries, prostate and breast cancer, with special emphasis on omics methods and outlined the prospects for their use in diagnosis.

Replication study: Melanoma exosomes educate bone marrow progenitor cells toward a pro-metastatic phenotype through MET

As part of the Reproducibility Project: Cancer Biology we published a Registered Report (Lesnik et al., 2016) that described how we intended to replicate selected experiments from the paper ‘Melanoma exosomes educate bone marrow progenitor cells toward a pro-metastatic phenotype through MET’ (Peinado et al., 2012). Here we report the results. We regenerated tumor cells stably expressing a short hairpin to reduce Met expression (shMet) using the same highly metastatic mouse melanoma cell line (B16-F10) as the original study, which efficiently downregulated Met in B16F10 cells similar to the original study (Supplementary Figure 5A; Peinado et al., 2012). Exosomes from control cells expressed Met, which was reduced in exosomes from shMet cells; however, we were unable to reliably detect phosphorylated Met in exosomes. We tested the effect of exosome-dependent Met signaling on primary tumor growth and metastasis. Similar to the results in the original study, we did not find a statistically significant change in primary tumor growth. Measuring lung and femur metastases, we found a small increase in metastatic burden with exosomes from control cells that was diminished when Met expression was reduced; however, while the effects were in the same direction as the original study (Figure 4E; Peinado et al., 2012), they were not statistically significant. Differences between the original study and this replication attempt, such as level of knockdown efficiency, cell line genetic drift, sample sizes, study endpoints, and variability of observed metastatic burden, are factors that might have influenced the outcomes. Finally, we report meta-analyses for each result.

The potential role of miRNAs and exosomes in chemotherapy in ovarian cancer

Chemoresistance is one of the major obstacles in the treatment of cancer patients. It poses a fundamental challenge to the effectiveness of chemotherapy and is often linked to relapse in patients. Chemoresistant cells can be identified in different types of cancers; however, ovarian cancer has one of the highest rates of chemoresistance-related relapse (50% of patients within 5 years). Resistance in cells can either develop through prolonged cycles of treatment or through intrinsic pathways. Mechanistically, the problem of drug resistance is complex mainly because numerous factors are involved, such as overexpression of drug efflux pumps, drug inactivation, DNA repair mechanisms and alterations to and/or mutations in the drug target. Additionally, there is strong evidence that circulating miRNAs participate in the development of chemoresistance. Recently, miRNAs have been identified in exosomes, where they are encapsulated and hence protected from degradation. These miRNAs within exosomes (exo-miRNAs) can regulate the gene expression of target cells both locally and systemically. Exo-miRNAs play an important role in disease progression and can potentially facilitate chemoresistance in cancer cells. In addition, and from a diagnostic perspective, exo-miRNAs profiles may contribute to the development of predictive models to identify responder and non-responder chemotherapy. Such model may also be used for monitoring treatment response and disease progression. Exo-miRNAs may ultimately serve as both a predictive biomarker for cancer response to therapy and as a prognostic marker for the development of chemotherapy resistance. Therefore, this review examines the potential role of exo-miRNAs in chemotherapy in ovarian cancer.

Post-translational and transcriptional dynamics - regulating extracellular vesicle biology

Introduction: Extracellular vesicles (EVs) are secreted into their extracellular environment, contain a specific repertoire of cellular cargo, and represent a novel vehicle for cell-cell communication. Protein post-translational modifications (PTMs) are emerging as major effectors of EV biology and function, and in turn, regulate cellular signaling. Areas covered: Discovery and investigation of PTMs such as methylation, glycosylation, acetylation, phosphorylation, sumoylation, and many others has established fundamental roles for PTMs within EVs and associated EV function. The application of enrichment strategies for modifications, high-resolution quantitative mass spectrometry-based proteomics, and improved technological approaches have provided key insights into identification and characterization of EV-based PTMs. Recently, an overwhelming appreciation for the diversity of modifications, including post-transcriptional modifications, dynamic roles of these modifications, and their emerging interplay, including protein-protein, protein-lipid, protein-RNA, and variable RNA modifications, is emerging. At a cellular level, such interplay is essential for gene expression/genome organization, protein function and localization, RNA metabolism, cell division, and cell signaling. Expert commentary: The understanding of these modifications and interactions will provide strategies toward how distinct cargo is localized, sorted, and delivered through EVs to mediate intercellular function, with further understanding of such modifications and intermolecular interactions will provide advances in EV-based therapeutic strategies.

Internalization of Exosomes through Receptor-Mediated Endocytosis

The tumor microenvironment is replete with factors secreted and internalized by surrounding cells. Exosomes are nano-sized, protein-embedded, membrane-bound vesicles that are released in greater quantities from cancer than normal cells and taken up by a variety of cell types. These vesicles contain proteins and genetic material from the cell of origin and in the case of tumor-derived exosomes, oncoproteins and oncogenes. With increasing understanding of the role exosomes play in basic biology, a more clear view of the potential exosomes are seen to have in cancer therapeutics emerges. However, certain essential aspects of exosome function, such as the uptake mechanisms, are still unknown. Various methods of cell-exosome interaction have been proposed, but this review focuses on the protein-protein interactions that facilitate receptor-mediated endocytosis, a broadly used mechanism by a variety of cells.

Cytoskeleton-associated protein 4 is a novel serodiagnostic marker for esophageal squamous-cell carcinoma

Background

Recent years have witnessed significant progress in the treatment of esophageal squamous-cell carcinoma (ESCC); however, the prognosis of ESCC is still unsatisfactory. Bio-markers are required to improve identification of high-risk populations and help management of ESCC. This study was to evaluate the role of serum CKAP4 in ESCC.

Methods

This longitudinal study recruited 207 ESCC patients and age-/sex-matched healthy controls. Circulating levels of CKAP4 were measured using ELISA kits, while the expression of CKAP4 in esophageal tissue was evaluated using Western blotting.

Results

Serum CKAP4 levels were higher in ESCC patients (380.2±171.3 pg/mL) than healthy controls (271.8±97.4 pg/mL; P<0.001). The area under the receiver-operating characteristic curve of serum CKAP4 levels to identify the presence of ESCC was 0.675 (95% CI 0.622–0.728; P<0.001). According to Youden’s index, the best cutoff value was 429.1 pg/mL (sensitivity 0.415 and specificity 0.995). Furthermore, after follow-up, multivariate analyses identified that pathological lymph node metastases were the poorest prognostic factor (HR 1.862, 95% CI 1.093–3.173; P=0.022), followed by serum CKAP4 (HR 1.437, 95% CI 1.025–2.014; P=0.035). When stratified by tertiles of serum CKAP4, subjects in the first tertile presented a mean survival time of 75.4 months (95% CI 68.0–81.9), which decreased significantly in the second tertile (73.8 months, 95% CI 61.4–86.3) and the third tertile (59.9 months, 95% CI 49.8–70.0, log-rank χ²=8.235; P=0.016).

Conclusion

These results suggested that serum CKAP4 could be a potential biomarker for clinical management of ESCC.

Exosomes for Non-Invasive Cancer Monitoring

Exosomes, membrane-bound phospholipid vesicles having diameters of 50-200 nm, are secreted by all cell types and circulate in human body fluids. These vesicles are known to carry cellular constituents that are specific to the originating cells (e.g., cytoplasmic/membrane proteins, RNA, and DNA). Thus, exosomes, which are both structurally stable and abundant, are robust indicators of cancers and, as a result, they have been utilized to monitor this disease in a manner that is less invasive than gold standard tissue biopsies. In this review, the history of exosomes and the specific biomarkers present in exosomes that enable accurate monitoring of various diseases are described. In addition, methods for analysis of exosomes and identification of biomarkers are presented with special emphasis being given to isolation and signaling strategies. Lastly, integrated, microfluidic systems developed for exosome-based cancer diagnosis are described and future directions that research in this area will likely take are presented.

Molecular assessment of circulating exosomes toward liquid biopsy diagnosis of Ewing sarcoma family of tumors

Ewing sarcoma was first described in 1921 in the Proceedings of the New York Pathological Society by an eminent American pathologist from Cornell named James R. Ewing as a "diffuse endothelioma of bone." Since this initial description, more has been discovered regarding Ewing sarcoma and in the 1980's both Ewing sarcoma and peripheral primitive neuroectodermal tumors due to their similar features and shared identical genetic abnormality were grouped into a class of cancers entitled Ewing sarcoma family of tumors (ESFTs). Ewing sarcoma is the second most common pediatric osseous malignancy followed by osteosarcoma, with highest incidence among 10-20 years old. Ewing sarcoma is consistently associated with chromosomal translocation and functional fusion of the EWSR1 gene to any of several structurally related transcription factor genes of the E26 transformation-specific family. These tumor-specific molecular rearrangements are useful for primary diagnosis, may provide prognostic information, and present potential therapeutic targets. Therefore, ways to rapidly and efficiently detect these defining genomic alterations are of clinical relevance. Within the past decade, liquid biopsies including extracellular vesicles (EVs), have emerged as a promising alternative and/or complimentary approach to standard tumor biopsies. It was recently reported that fusion mRNAs from tumor-specific chromosome translocations can be detected in Ewing sarcoma cell-derived exosomes. Within this review, we overview the current advances in Ewing sarcoma and the opportunities and challenges in exploiting circulating exosomes, primarily small bioactive EVs (30-180 nm), as developing sources of biomarkers for diagnosis and therapeutic response monitoring in children and young adult patients with ESFT.

Microfluidic affinity separation chip for selective capture and release of label-free ovarian cancer exosomes

Exosomes are nanoscale vesicles found in many bodily fluids which play a significant role in cell-to-cell signaling and contain biomolecules indicative of their cells of origin. Recently, microfluidic devices have provided the ability to efficiently capture exosomes based on specific membrane biomarkers, but releasing the captured exosomes intact and label-free for downstream characterization and experimentation remains a challenge. We present a herringbone-grooved microfluidic device which is covalently functionalized with antibodies against general and cancer exosome membrane biomarkers (CD9 and EpCAM) to isolate exosomes from small volumes of high-grade serous ovarian cancer (HGSOC) serum. Following capture, intact exosomes are released label-free using a low pH buffer and immediately neutralized downstream to ensure their stability. Characterization of captured and released exosomes was performed using fluorescence microscopy, nanoparticle tracking analysis, flow-cytometry, and SEM. Our results demonstrate the successful isolation of intact and label-free exosomes, indicate that the amount of both total and EpCAM+ exosomes increases with HGSOC disease progression, and demonstrate the downstream internalization of isolated exosomes by OVCAR8 cells. This device and approach can be utilized for a nearly limitless range of downstream exosome analytical and experimental techniques, both on and off-chip.

Proteomic analysis of exosomes reveals an association between cell invasiveness and exosomal bioactivity on endothelial and mesenchymal cell migration in vitro

Ovarian cancer has resulted in over 140 000 deaths reported annually worldwide. This is often attributed to cellular changes in the microenvironment, including increased migration of mesenchymal stem cells (MSCs) and endothelial cells (ECs) to facilitate metastasis. Recently, the ability of exosomes to communicate signals between cells (and promote cancer progression) has been established. In the present study, we explored the effect of exosomes on cells present in the tumour microenvironment. Exosomes were isolated from ovarian cancer cells with different invasive capacity (high = SKOV-3 and low = OVCAR-3) by differential and buoyant density centrifugation and characterised using nanoparticle tracking analysis (NTA), Western blot, and EM. Exosome secretion was positively correlated with invasiveness of releasing cells. Proteomic analyses identified common and unique proteins between exosomes from SKOV-3 and OVCAR-3 with gene ontology analyses revealing that these exosomes are involved in the regulation of cell migration. Since the tumour microenvironment contains multiple cell types, including MSCs and ECs, we examined the effect of these exosomes on MSC and EC migration. Exosomes promoted MSC and EC migration in a time- and concentration-dependent manner. The effect of exosomes isolated from SKOV-3 on cell migration was significantly higher compared with exosomes from OVCAR-3. Thus, we suggest that exosomes from ovarian cancer cells contain a specific set of proteins that are representative of its cell of origin and the invasive capacity.

Hypoxia-induced exosomes contribute to a more aggressive and chemoresistant ovarian cancer phenotype: a novel mechanism linking STAT3/Rab proteins

Hypoxia-mediated tumor progression, metastasis, and drug resistance are major clinical challenges in ovarian cancer. Exosomes released in the hypoxic tumor microenvironment may contribute to these challenges by transferring signaling proteins between cancer cells and normal cells. We observed that ovarian cancer cells exposed to hypoxia significantly increased their exosome release by upregulating Rab27a, downregulating Rab7, LAMP1/2, NEU-1, and also by promoting a more secretory lysosomal phenotype. STAT3 knockdown in ovarian cancer cells reduced exosome release by altering the Rab family proteins Rab7 and Rab27a under hypoxic conditions. We also found that exosomes from patient-derived ascites ovarian cancer cell lines cultured under hypoxic conditions carried more potent oncogenic proteins-STAT3 and FAS that are capable of significantly increasing cell migration/invasion and chemo-resistance in vitro and tumor progression/metastasis in vivo. Hypoxic ovarian cancer cells derived exosomes (HEx) are proficient in re-programming the immortalized fallopian tube secretory epithelial cells (FT) to become pro-tumorigenic in mouse fallopian tubes. In addition, cisplatin efflux via exosomes was significantly increased in ovarian cancer cells under hypoxic conditions. Co-culture of HEx with tumor cells led to significantly decreased dsDNA damage and increased cell survival in response to cisplatin treatment. Blocking exosome release by known inhibitor Amiloride or STAT3 inhibitor and treating with cisplatin resulted in a significant increase in apoptosis, decreased colony formation, and proliferation. Our results demonstrate that HEx are more potent in augmenting metastasis/chemotherapy resistance in ovarian cancer and may serve as a novel mechanism for tumor metastasis, chemo-resistance, and a point of intervention for improving clinical outcomes.

Measuring zinc in biological nanovesicles by multiple analytical approaches

Exosomes are nanovesicles known to mediate intercellular communication. Although it is established that zinc ions can act as intracellular signaling factors, the measurement of zinc in circulating nanovesicles has not yet been attempted. Providing evidence of the existence of this zinc fraction and methods for its measurement might be important to advance our knowledge of zinc status and its relevance in diseases. Exosomes from 0.5 ml of either fresh or frozen human plasma were isolated by differential centrifugation. A morphological and dimensional evaluation at the nanoscale level was performed by atomic force microscopy (AFM) and Transmission Electron Microscopy (TEM). Energy Dispersive X-Ray Microanalysis (EDX) revealed the elemental composition of exosomes and their respective total Zinc content on a quantitative basis. The zinc mole fraction (in at%) was correlated to the phosphorous mole fraction, which is indicative for exosomal membrane material. Both fresh (Zn/P 0.09 ± 0.01) and frozen exosomes (Zn/P 0.08 ± 0.02) had a significant zinc content, which increased up to 1.09 ± 0.12 for frozen exosomes when treated with increasing amounts of zinc (100-500 μM; each p < 0.05). Interestingly, after zinc addition, the Calcium mole fractions decreased accordingly suggesting a possible exchange by zinc. In order to estimate the intra-exosomal labile zinc content, an Imaging Flow Cytometry approach was developed by using the specific membrane permeable zinc-probe Fluozin-3AM. A labile zinc content of 0.59 ± 0.27 nM was calculated but it is likely that the measurement may be affected by purification and isolation conditions. This study suggests that circulating nano-vesicular-zinc can represent a newly discovered zinc fraction in the blood plasma whose functional and biological properties will have to be further investigated in future studies.

Identification of anti-SF3B1 autoantibody as a diagnostic marker in patients with hepatocellular carcinoma

BACKGROUND

Tumor-associated (TA) autoantibodies, which are generated by the immune system upon the recognition of abnormal TA antigens, are promising biomarkers for the early detection of tumors. In order to detect autoantibody biomarkers effectively, antibody-specific epitopes in the diagnostic test should maintain the specific conformations that are as close as possible to those presenting in the body. However, when using patients' serum as a source of TA autoantibodies the characterization of the autoantibody-specific epitope is not easy due to the limited amount of patient-derived serum.

METHODS

To overcome these limits, we constructed a B cell hybridoma pool derived from a hepatocellular carcinoma (HCC) model HBx-transgenic mouse and characterized autoantibodies derived from them as tumor biomarkers. Their target antigens were identified by mass spectrometry and the correlations with HCC were examined. With the assumption that TA autoantibodies generated in the tumor mouse model are induced in human cancer patients, the enzyme-linked immunosorbent assays (ELISA) based on the characteristics of mouse TA autoantibodies were developed for the detection of autoantibody biomarkers in human serum. To mimic natural antigenic structures, the specific epitopes against autoantibodies were screened from the phage display cyclic random heptapeptide library, and the streptavidin antigens fused with the specific epitopes were used as coating antigens.

RESULTS

In this study, one of HCC-associated autoantibodies derived from HBx-transgenic mouse, XC24, was characterized. Its target antigen was identified as splicing factor 3b subunit 1 (SF3B1) and the high expression of SF3B1 was confirmed in HCC tissues. The specific peptide epitopes against XC24 were selected and, among them, XC24p11 cyclic peptide (-CDATPPRLC-) was used as an epitope of anti-SF3B1 autoantibody ELISA. With this epitope, we could effectively distinguish between serum samples from HCC patients (n = 102) and healthy subjects (n = 85) with 73.53% sensitivity and 91.76% specificity (AUC = 0.8731). Moreover, the simultaneous detection of anti-XC24p11 epitope autoantibody and AFP enhanced the efficiency of HCC diagnosis with 87.25% sensitivity and 90.59% specificity (AUC = 0.9081).

CONCLUSIONS

ELISA using XC24p11 peptide epitope that reacts against anti-SF3B1 autoantibody can be used as a novel test to enhance the diagnostic efficiency of HCC.

Uptake Profiles of Human Serum Exosomes by Murine and Human Tumor Cells through Combined Use of Colloidal Nanoplasmonics and Flow Cytofluorimetric Analysis

Understanding extracellular vesicle (EV) internalization mechanisms and pathways in cells is of capital importance for both EV basic biology and clinical translation, but still presents analytical hurdles, such as undetermined purity grade and/or concentration of the EV samples and lack of standard protocols. We report an accessible, robust, and versatile method for resolving dose-dependent uptake profiles of exosomes-the nanosized (30-150 nm) subtypes of EVs of intracellular origin which are more intensively investigated for diagnostic and therapeutic applications-by cultured cells. The method is based on incubating recipient cells with consistently increasing doses of exosomes which are graded for purity and titrated by a COlorimetric NANoplasmonic (CONAN) assay followed by cell flow cytofluorimetric analysis. The proposed method allowed evaluation and comparison of the uptake of human serum exosomes by cancer cell lines of murine (TRAMP-C2) and human (LNCaP, DU145, MDA-MB-231, and A375) origin, setting a firmer footing for better characterization and understanding of exosome biology in different in vitro and (potentially) in vivo models of cancer growth.

Rab35-dependent extracellular nanovesicles are required for induction of tumour supporting stroma

Communication between diseased cells and the microenvironment is a complex yet crucial element in progression of varied pathological processes. Recent studies in cancer highlight an important role for small extracellular nanovesicles secreted by cancer cells as modulators of cancer-associated stroma, leading to enhanced angiogenesis and metastatic priming. The intrinsic factors regulating extracellular nanovesicle biogenesis and secretion are therefore relevant in studies of nano-communication in the cancer milieu. We generated prostate cancer cells bearing stable knockdown of several candidate vesicle regulating factors and examined the impact on cell health, vesicle secretion and on communication with fibroblastic stromal cells. We highlight that RAB11B and RAB35 regulate phenotypically distinct nanovesicle populations, each accounting for only around 20% of the total. Depleting RAB35, but not RAB11B leaves a remaining population of vesicles whose phenotype is insufficient for driving fibroblast to myofibroblast differentiation, leading to attenuated motile behaviours in 3D in vitro models. Co-implantation of tumour cells with stromal fibroblasts in xenografts similarly showed that RAB11B knockdown had little effect on growth rates in vivo. In contrast, significant attenuation in growth, and attenuation of myofibroblasts at the tumour site was evident when using RAB35-knockdown cells. The study concludes that a RAB35 regulated nanovesicle sub-population is particularly important for communication between cancer and stromal cells, and is required for generating a tumour-supportive microenvironment.

Exosome markers associated with immune activation and oxidative stress in HIV patients on antiretroviral therapy

Exosomes are nanovesicles released from most cell types including immune cells. Prior studies suggest exosomes play a role in HIV pathogenesis, but little is known about exosome cargo in relation to immune responses and oxidative stress. Here, we characterize plasma exosomes in HIV patients and their relationship to immunological and oxidative stress markers. Plasma exosome fractions were isolated from HIV-positive subjects on ART with suppressed viral load and HIV-negative controls. Exosomes were characterized by electron microscopy, nanoparticle tracking, immunoblotting, and LC-MS/MS proteomics. Plasma exosomes were increased in HIV-positive subjects compared to controls, and correlated with increased oxidative stress markers (cystine, oxidized cys-gly) and decreased PUFA (DHA, EPA, DPA). Untargeted proteomics detected markers of exosomes (CD9, CD63, CD81), immune activation (CD14, CRP, HLA-A, HLA-B), oxidative stress (CAT, PRDX1, PRDX2, TXN), and Notch4 in plasma exosomes. Exosomal Notch4 was increased in HIV-positive subjects versus controls and correlated with immune activation markers. Treatment of THP-1 monocytic cells with patient-derived exosomes induced expression of genes related to interferon responses and immune activation. These results suggest that exosomes in ART-treated HIV patients carry proteins related to immune activation and oxidative stress, have immunomodulatory effects on myeloid cells, and may have pro-inflammatory and redox effects during pathogenesis.