Analysis of AKT and ERK1/2 protein kinases in extracellular vesicles isolated from blood of patients with cancer

Extracellular vesicles from obese and diabetic mouse plasma alter C2C12 myotube glucose uptake and gene expression

Recent studies have indicated a role for circulating extracellular vesicles (EVs) in the pathogenesis of multiple diseases. However, most in vitro studies have used variable and arbitrary doses of EVs rather than interpreting EVs as an existing component of standard skeletal muscle cell culture media. The current study provides an initial investigation into the effects of circulating EVs on the metabolic phenotype of C2C12 myotubes by replacing EVs from fetal bovine serum with circulating EVs from control mice or mice with obesity and type 2 diabetes (OT2D). We report that EVs associated with OT2D decrease 2-NBDG uptake (a proxy measure of glucose uptake) in the insulin-stimulated state compared to controls. OT2D associated EV treatment also significantly decreased myosin heavy chain type 1 (MHCI) mRNA abundance in myotubes but had no effect on mRNA expression of any other myosin heavy chain isoforms. OT2D-associated circulating EVs also significantly increased lipid accumulation within myotubes without altering the expression of a selection of genes important for lipid entry, synthesis, or catabolism. The data indicate that, in a severely diabetic state, circulating EVs may contribute to insulin resistance and alter gene expression in myotubes in a manner consistent with the skeletal muscle phenotype observed in OT2D.

Recent advances of small extracellular vesicle biomarkers in breast cancer diagnosis and prognosis

Current clinical tools for breast cancer (BC) diagnosis are insufficient but liquid biopsy of different bodily fluids has recently emerged as a minimally invasive strategy that provides a real-time snapshot of tumour biomarkers for early diagnosis, active surveillance of progression, and post-treatment recurrence. Extracellular vesicles (EVs) are nano-sized membranous structures 50-1000 nm in diameter that are released by cells into biological fluids. EVs contain proteins, nucleic acids, and lipids which play pivotal roles in tumourigenesis and metastasis through cell-to-cell communication. Proteins and miRNAs from small EVs (sEV), which range in size from 50-150 nm, are being investigated as a potential source for novel BC biomarkers using mass spectrometry-based proteomics and next-generation sequencing. This review covers recent developments in sEV isolation and single sEV analysis technologies and summarises the sEV protein and miRNA biomarkers identified for BC diagnosis, prognosis, and chemoresistance. The limitations of current sEV biomarker research are discussed along with future perspective applications.

Spectral flow cytometry identifies distinct nonneoplastic plasma extracellular vesicle phenotype in glioblastoma patients

Background

Glioblastoma (GBM) is the most common malignant brain tumor and has a poor prognosis. Imaging findings at diagnosis and in response to treatment are nonspecific. Developing noninvasive assays to augment imaging would be helpful. Plasma extracellular vesicles (EVs) are a promising biomarker source for this. Here, we develop spectral flow cytometry techniques that demonstrate differences in bulk plasma EV phenotype between GBM patients and normal donors that could serve as the basis of a liquid biopsy.

Methods

Plasma EVs were stained for EV-associated tetraspanins (CD9/CD63/CD81), markers indicating cell of origin (CD11b/CD31/CD41a/CD45), and actin/phalloidin (to exclude cell debris). EVs were analyzed using spectral flow cytometry. Multiparametric analysis using t-distributed stochastic neighbor embedding (t-SNE) and self-organizing maps on flow cytometry data (FlowSOM) was performed comparing GBM and normal donor (ND) plasma EVs.

Results

Size exclusion chromatography plus spectral-based flow cytometer threshold settings enriched plasma EVs while minimizing background noise. GBM patients had increased CD9+, CD63+, CD81+, and myeloid-derived (CD11b+) EVs. Multiparametric analysis demonstrated distinct surface marker expression profiles in GBM plasma EVs compared to ND EVs. Fifteen plasma EV sub-populations differing in size and surface marker expression were identified, six enriched in GBM patients and two in normal donors.

Conclusions

Multiparametric analysis demonstrates that GBM patients have a distinct nonneoplastic plasma EV phenotype compared to ND. This simple rapid analysis can be performed without purifying tumor EVs and may serve as the basis of a liquid biopsy.

Insulin infusion decreases medium-sized extracellular vesicles in adults with metabolic syndrome

Elevated extracellular vesicles (EVs) are associated with glucose dysmetabolism. However, the effects of insulin on EVs and subsequent relationships with insulin sensitivity, substrate oxidation, and inflammation are unknown. We tested the hypothesis that insulin would lower EVs and relate to insulin action. Fifty-one sedentary adults (54.8 ± 1.0 yr; V̇o2peak : 22.1 ± 0.6 mL/kg/min) with metabolic syndrome (MetS) and obesity (36.4 ± 0.65 kg/m2) underwent a 2-h euglycemic-hyperinsulinemic clamp (5 mmol/L; 40 mU/m2/min). Count and size (medium: 200-624 nm; larger: 625-1,000 nm) for total particle count, endothelial- (CD105+), leukocyte- (CD45+), platelet- (CD41+), and tetraspanin- (TX+: CD9/CD81/CD63), as well as platelet endothelial cell adhesion molecule- (CD31+) derived EVs were determined before and following the clamp using Full Spectrum Profiling (FSPM). Size and MESF (molecules of equivalent soluble fluorochrome) data were generated using FCMPASS Software. Fat and carbohydrate oxidation, in addition to high-sensitivity c-reactive protein (hsCRP), were measured to understand insulin effects and associations between EVs, metabolic flexibility, and inflammation. Despite low metabolic insulin sensitivity (M-Value = 2.56 ± 0.17 mg/kg/min), insulin increased carbohydrate (P = 0.015) and decreased fat oxidation (P = 0.048) and hsCRP (P = 0.016) compared with fasting. Insulin also decreased total particle count (P < 0.001), attributable to decreased medium-sized CD105+ (P = 0.052) and CD45+ EVs (P < 0.001). Elevated fasting insulin was associated with reduced insulin-stimulated changes in all EVs phenotypes (P < 0.001). Interestingly, fasting EVs were associated with increased fasting carbohydrate oxidation (all P < 0.05). These findings suggest that insulin decreases medium-sized EVs in conjunction with metabolic flexibility under euglycemic conditions in adults with MetS. More research is needed to determine how therapies alter EV phenotype/size and consequent cardiometabolic risk.NEW & NOTEWORTHY This study is one of the first to investigate the effects of insulin on medium and larger extracellular vesicles (EVs) in relation to metabolic insulin sensitivity and fuel use in adults with metabolic syndrome. Our data suggest that insulin infusion decreases the concentration of total particle counts, mainly due to reductions in medium-sized EVs. Furthermore, EVs, predominantly medium-sized, are inversely associated with metabolic flexibility.

Purification and Phosphoproteomic Analysis of Plasma-Derived Extracellular Vesicles

A successful phosphoproteomics analysis of extracellular vesicles (EVs) requires a unique approach, fine-tuned to address the challenges that have plagued plasma-based biomarker discovery. Here, I detail a procedure, which combines EVtrap-based high-recovery EV isolation, phase-transfer surfactant method for protein extraction, and PolyMAC-based enrichment of phosphopeptides. The combination of these methods provides a highly effective strategy for EV-based phosphoproteome analysis and leads to the discovery of novel phospho-markers previously undetectable.

Longitudinal stability of urinary extracellular vesicle protein patterns within and between individuals

The protein content of urinary extracellular vesicles (EVs) is considered to be an attractive non-invasive biomarker source. However, little is known about the consistency and variability of urinary EV proteins within and between individuals over a longer time-period. Here, we evaluated the stability of the urinary EV proteomes of 8 healthy individuals at 9 timepoints over 6 months using data-independent-acquisition mass spectrometry. The 1802 identified proteins had a high correlation amongst all samples, with 40% of the proteome detected in every sample and 90% detected in more than 1 individual at all timepoints. Unsupervised analysis of top 10% most variable proteins yielded person-specific profiles. The core EV-protein-interaction network of 516 proteins detected in all measured samples revealed sub-clusters involved in the biological processes of G-protein signaling, cytoskeletal transport, cellular energy metabolism and immunity. Furthermore, gender-specific expression patterns were detected in the urinary EV proteome. Our findings indicate that the urinary EV proteome is stable in longitudinal samples of healthy subjects over a prolonged time-period, further underscoring its potential for reliable non-invasive diagnostic/prognostic biomarkers.

A new urinary exosome enrichment method by a combination of ultrafiltration and TiO2 nanoparticles

Exosomes are small membrane-bound vesicles secreted by most cell types and play an important role in cell-to-cell communication. Increasing evidence shows that exosomal proteins in urine may be used as novel biomarkers for certain diseases. Purified urinary exosomes are necessary for downstream studies and application development. However, conventional methods for exosome isolation and enrichment are technically challenging and time-consuming. Poor specificity, low recovery and instrumental dependence also limit the use of these methods. It is particularly urgent to develop a rapid and efficient extraction method for basic research and clinical application. Particularly, urine is a dilute solution system with relatively low abundance of exosomes, due to which the isolation of urinary exosome requires more efficient technology. Here, we propose a new strategy for facile exosome isolation from human urine by utilizing the ultrafiltration technique and the specific interaction of TiO₂ with the phosphate groups on the lipid bilayer of exosomes. Downstream characterization and proteomic analysis indicate that high-quality exosomes can be obtained from human urine by this ultrafiltration-TiO₂ series method in 20 minutes, and 91.5% exosomes with an intact structure are captured from urine by this method. Moreover, 1874 protein groups have been identified through LC-MS. The results show that the protein identification of our method is 23% higher at least than those obtained by conventional strategies. We also identified 30 differential proteins by comparing the urinary exosomes from healthy male and female volunteers. These proteins are related to biological processes, such as lipid metabolism, fatty acid metabolism and nucleotide metabolism. Our analysis reveals that combining conventional ultrafiltration and TiO₂-based isolation is ideal to overcome the inherent limitations of identification of exosome proteins derived from urine, and yield highly pure exosome components for downstream proteomic analysis.

Feasibility of phosphoproteomics to uncover oncogenic signalling in secreted extracellular vesicles using glioblastoma-EGFRVIII cells as a model

Cancer cells secrete extracellular vesicles (EVs) that contain molecular information, including proteins and RNA. Oncogenic signalling can be transferred via the cargo of EVs to recipient cells and may influence the behaviour of neighbouring cells or cells at a distance. This cargo may contain cancer drivers, such as EGFR, and also phosphorylated (activated) components of oncogenic signalling cascades. Till date, the cancer EV phosphoproteome has not been studied in great detail. In the present study, we used U87 and U87EGFRvIII cells as a model to explore EV oncogenic signalling components in comparison to the cellular profile. EVs were isolated using the VN96 ME-kit and subjected to LC-MS/MS based phosphoproteomics and dedicated bioinformatics. Expression of (phosphorylated)-EGFR was highly increased in EGFRvIII overexpressing cells and their secreted EVs. The increased phosphorylated proteins in both cells and EVs were associated with activated components of the EGFR-signalling cascade and included EGFR, AKT2, MAPK8, SMG1, MAP3K7, DYRK1A, RPS6KA3 and PAK4 kinases. In conclusion, EVs harbour oncogenic signalling networks including multiple activated kinases including EGFR, AKT and mTOR. SIGNIFICANCE: Extracellular vesicles (EVs) are biomarker treasure troves and are widely studied for their biomarker content in cancer. However, little research has been done on the phosphorylated protein profile within cancer EVs. In the current study, we demonstrate that EVs that are secreted by U87-EGFRvIII mutant glioblastoma cells contain high levels of oncogenic signalling networks. These networks contain multiple activated (phosphorylated) kinases, including EGFR, MAPK, AKT and mTOR.

Liquid Biopsy Strategies to Distinguish Progression from Pseudoprogression and Radiation Necrosis in Glioblastomas

Liquid biopsy for the detection and monitoring of central nervous system tumors is of significant clinical interest. At initial diagnosis, the majority of patients with central nervous system tumors undergo magnetic resonance imaging (MRI), followed by invasive brain biopsy to determine the molecular diagnosis of the WHO 2016 classification paradigm. Despite the importance of MRI for long-term treatment monitoring, in the majority of patients who receive chemoradiation therapy for glioblastoma, it can be challenging to distinguish between radiation treatment effects including pseudoprogression, radiation necrosis, and recurrent/progressive disease based on imaging alone. Tissue biopsy-based monitoring is high risk and not always feasible. However, distinguishing these entities is of critical importance for the management of patients and can significantly affect survival. Liquid biopsy strategies including circulating tumor cells, circulating free DNA, and extracellular vesicles have the potential to afford significant useful molecular information at both the stage of diagnosis and monitoring for these tumors. Here, current liquid biopsy-based approaches in the context of tumor monitoring to differentiate progressive disease from pseudoprogression and radiation necrosis are reviewed.

Glass Fiber-Supported Hybrid Monolithic Spin Tip for Enrichment of Phosphopeptides from Urinary Extracellular Vesicles

Extracellular vesicles (EVs) are attracting increasing interest with their intriguing role in intercellular communications. Protein phosphorylation in EVs is of great importance for understanding intercellular signaling processes. However, the study of EV phosphoproteomics is impeded by their relatively low amount in limited clinical sample volumes, and it is necessary to have a sensitive and efficient enrichment method for EV phosphopeptides. Herein, a novel Ti(IV)-functionalized and glass fiber-supported hybrid monolithic spin tip, termed PhosTip, was prepared for enriching phosphopeptides from urinary EVs. Glass fiber as the stationary phase positions the hybrid monolith in a standard pipet tip and prevents the monolith from distortion during experiments. The preparation procedure for the new PhosTip is simple and time-saving. The hybrid monolithic PhosTip provides excellent enrichment efficiency of low-abundance phosphopeptides from cell digests and urinary EVs with minimum contamination and sample loss. Using the PhosTip, we demonstrate that 5373 and 336 unique phosphopeptides were identified from 100 and 1 μg of cell lysates, while 3919 and 217 unique phosphopeptides were successfully identified from 10 and 1 mL of urinary samples, respectively. The PhosTip was finally applied to enrich phosphopeptides in urine EVs from prostate cancer patients and healthy controls and quantify 118 up-regulated proteins with phosphosites in prostate cancer samples. These results demonstrated that the PhosTip could be a simple and convenient tool for enriching phosphopeptides from clinical samples and for broader applications in biomarker discovery.

EGFR-rich extracellular vesicles derived from highly metastatic nasopharyngeal carcinoma cells accelerate tumour metastasis through PI3K/AKT pathway-suppressed ROS

Nasopharyngeal carcinoma (NPC) is the most common cancer with high metastatic potential that occurs in the epithelial cells of the nasopharynx. Distant metastases are the primary cause for treatment failure and mortality of NPC patients. However, the underlying mechanism responsible for the initiation of tumour cell dissemination and tumour metastasis in NPC is not well understood. Here, we demonstrated that epidermal growth factor receptor (EGFR) was highly expressed in tumour tissues of NPC patients with distant metastases and was associated with a decrease in reactive oxygen species (ROS). We also revealed that extracellular vesicles (EVs) transfer occurred from highly to poorly metastatic NPC cells, mediating cell-cell communication and enhancing the metastatic potential of poorly metastatic NPC cells. Further experiments indicated that EVs derived from highly metastatic NPC cells induced the up-regulation of EGFR and down-regulation of ROS in low metastatic NPC cells. Mechanistically, EGFR-rich EVs-mediated EGFR overexpression down-regulated intracellular ROS levels through the PI3K/AKT pathway, thus promoting the metastatic potential of poorly metastatic NPC cells. Strikingly, treatment with EVs secreted from highly metastatic NPC cells was significantly associated with rapid NPC progression and shorter survival in xenografted mice. These findings not only improve our understanding of EVs-mediated NPC metastatic mechanism but also have important implications for the detection and treatment of NPC patients accompanied by aberrant EGFR-rich EVs transmission.

Extracellular Vesicles in Non-Small-Cell Lung Cancer: Functional Role and Involvement in Resistance to Targeted Treatment and Immunotherapy

Targeted and immunological therapies have become the gold standard for a large portion of non-small cell lung cancer (NSCLC) patients by improving significantly clinical prognosis. However, resistance mechanisms inevitably develop after a first response, and almost all patients undergo progression. The knowledge of such a resistance mechanism is crucial to improving the efficacy of therapies. So far, monitoring therapy responses through liquid biopsy has been carried out mainly in terms of circulating tumor (ctDNA) analysis. However, other particles of tumor origin, such as extracellular vehicles (EVs) represent an emerging tool for the studying and monitoring of resistance mechanisms. EVs are now considered to be ubiquitous mediators of cell-to-cell communication, allowing cells to exchange biologically active cargoes that vary in response to the microenvironment and include proteins, metabolites, RNA species, and nucleic acids. Novel findings on the biogenesis and fate of these vesicles reveal their fundamental role in cancer progression, with foreseeable and not-far-to-come clinical applications in NSCLC.

Role of liquid biopsy in oncogene-addicted non-small cell lung cancer

The discovery of actionable oncogene in non-small cell lung cancer (NSCLC) allowed the identification of a subgroup of patients who benefit from targeted tyrosine kinase inhibitors more than others. Mutations in the epidermal growth factor receptor (EGFR), translocations in the anaplastic lymphoma kinase (ALK) and rearrangements in the ROS proto-oncogene 1 (ROS1) must be identified in tumor tissue to guide the proper treatment choice. Liquid biopsy is based on the analysis of tumor materials released in the circulation. Liquid biopsy can be complementary to tissue biopsy, both at baseline and at progression, especially in the detection of somatic gene alterations emerging during the treatment with tyrosine kinase inhibitors (TKIs). Particularly, circulating DNA is used to find mutations in driver oncogenes, while circulating tumor cells, extracellular vesicles (EVs) and cell-free microRNAs (cfmiRNAs) are still under investigation. To help the unbiased use of liquid biopsy in the choice of the appropriate therapy, some recommendations were delivered by expert panels. Currently, analysis of EGFR mutations in cell-free DNA (cfDNA) is recommended at baseline when tissue biopsy harbors scarce tumor cells, and at progression before performing tissue biopsy; liquid biopsy analysis for other oncogenic drivers is not indicated in the clinical practice.

Liquid Biopsy for the Detection of Resistance Mechanisms in NSCLC: Comparison of Different Blood Biomarkers

The use of targeted agents and immunotherapy for the treatment of advanced non-small-cell lung cancer (NSCLC) has made it mandatory to characterize tumor tissue for patient selection. Moreover, the development of agents that are active against specific resistance mechanisms arising during treatment make it equally important to characterize the tumor tissue at progression by performing tissue re-biopsy. Given that tumor tissue is not always available for molecular characterization due to the paucity of diagnostic specimens or problems relating to the carrying out of invasive procedures, the use of liquid biopsy represents a valid approach to overcoming these difficulties. The most common material used for liquid biopsy in this setting is plasma-derived cell free DNA (cfDNA), which originates from cells undergoing apoptosis or necrosis. However, other sources of tumor material can be considered, such as extracellular vesicle (EV)-derived nucleic acids, which are actively secreted from living cells and closely correspond to tumor dynamics. In this review, we discuss the role of liquid biopsy in the therapeutic management of NSCLC with particular regard to targeted therapy and immunotherapy, and analyze the pros and cons of the different types of samples used in this context.

INKA, an integrative data analysis pipeline for phosphoproteomic inference of active kinases

Identifying hyperactive kinases in cancer is crucial for individualized treatment with specific inhibitors. Kinase activity can be discerned from global protein phosphorylation profiles obtained with mass spectrometry-based phosphoproteomics. A major challenge is to relate such profiles to specific hyperactive kinases fueling growth/progression of individual tumors. Hitherto, the focus has been on phosphorylation of either kinases or their substrates. Here, we combined label-free kinase-centric and substrate-centric information in an Integrative Inferred Kinase Activity (INKA) analysis. This multipronged, stringent analysis enables ranking of kinase activity and visualization of kinase-substrate networks in a single biological sample. To demonstrate utility, we analyzed (i) cancer cell lines with known oncogenes, (ii) cell lines in a differential setting (wild-type versus mutant, +/- drug), (iii) pre- and on-treatment tumor needle biopsies, (iv) cancer cell panel with available drug sensitivity data, and (v) patient-derived tumor xenografts with INKA-guided drug selection and testing. These analyses show superior performance of INKA over its components and substrate-based single-sample tool KARP, and underscore target potential of high-ranking kinases, encouraging further exploration of INKA's functional and clinical value.

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.

Soluble AXL is ubiquitously present in malignant serous effusions

OBJECTIVE

The objective of this study was to analyze the expression level and clinical role of soluble AXL (sAXL) in cancers affecting the serosal surfaces, with focus on ovarian carcinoma.

METHODS

sAXL protein expression by ELISA was analyzed in 572 effusion supernatants, including 424 peritoneal, 147 pleural and 1 pericardial specimens.

RESULTS

sAXL was overexpressed in peritoneal effusions compared to pleural and pericardial specimens (p < 0.001). sAXL levels were additionally significantly higher in effusions from patients with ovarian carcinoma, malignant mesothelioma and breast carcinoma compared to specimens from patients with other cancers (predominantly carcinomas of lung, gastrointestinal or uterine corpus/cervix origin) or benign reactive effusions (p < 0.001). sAXL was further overexpressed in high-grade serous carcinoma (HGSC; n = 373) compared to low-grade serous carcinoma (LGSC; n = 32; p = 0.036). In HGSC, sAXL levels were significantly lower in post-chemotherapy effusions compared to primary diagnosis pre-chemotherapy specimens (p = 0.002). sAXL levels in HGSC were unrelated to chemoresponse at diagnosis, progression-free survival or overall survival. Levels were similarly unrelated to survival in LGSC and breast carcinoma.

CONCLUSIONS

sAXL is widely expressed in malignant effusions, particularly in ovarian and breast carcinoma and in malignant mesothelioma. sAXL is overexpressed in HGSC compared to LGSC and its levels are lower following exposure to chemotherapy. However, sAXL levels are not informative of chemoresponse or survival.

Single-Molecule Co-Immunoprecipitation Reveals Functional Inheritance of EGFRs in Extracellular Vesicles

Cancer cells actively release extracellular vesicles (EVs) as important carriers of cellular information to tumor microenvironments. Although the composition and quantity of the proteins contained in EVs are characterized, it remains unknown how these proteins in EVs are related to those in the original cells at the functional level. With epidermal growth factor receptor (EGFR) in lung adenocarcinoma cells as a model oncoprotein, it is studied how distinct types of EVs, microvesicles and exosomes, represent their original cells at the protein and protein-protein interaction (PPI) level. Using the recently developed single-molecule immunolabeling and co-immunoprecipitation schemes, the quantity and PPI strengths of EGFRs derived from EVs and the original lung adenocarcinoma cells are determined. It is found that the microvesicles exhibit higher correlations with the original cells than the exosomes in terms of the EGFR levels and their PPI patterns. In spite of these detailed differences between the microvesicles and exosomes, the EGFR PPI strengths measured for EVs generally show a tight correlation with those determined for the original cells. The results suggest that EGFRs contained in EVs closely reflect the cellular EGFR in terms of their downstream signaling capacity.

Highly Efficient Phosphoproteome Capture and Analysis from Urinary Extracellular Vesicles

Analysis of protein phosphorylation in extracellular vesicles (EVs) offers an unprecedented potential for understanding cancer signaling and early stage disease diagnosis. However, prior to the phosphoproteome analysis step, the isolation of EVs from biofluids remains a challenging issue to overcome due to the low yield and impurity from current isolation methods. Here, we carry out an extensive assessment of several EV isolation methods including a novel rapid isolation method EVTRAP for highly efficient capture of extracellular vesicles from human urine sample. We demonstrate that over 95% recovery yield can be consistently achieved by EVTRAP, a significant improvement over current standard techniques. We then applied EVTRAP to identify over 16 000 unique peptides representing 2000 unique EV proteins from 200 μL urine sample, including all known EV markers with substantially increased recovery levels over ultracentrifugation. Most importantly, close to 2000 unique phosphopeptides were identified from more than 860 unique phosphoproteins using 10 mL of urine. The data demonstrated that EVTRAP is a highly effective and potentially widely implementable clinical isolation method for analysis of EV protein phosphorylation.

Quantification and localization of oncogenic receptor tyrosine kinase variant transcripts using molecular inversion probes

Oncogenic membrane receptor tyrosine kinases such as MET and EGFR, or auto-active variants thereof, are important targets for cancer precision therapy. Targeted inhibition of these oncogenic receptors however invariably leads to resistance, resulting from acquisition of resistance-inducing mutations or from selective outgrowth of a priori resistant tumour cells. Most applied molecular protocols cannot distinguish between intracellular and intercellular heterogeneity of oncogene (variant) expression, which may lead to misinterpretation of the molecular make-up of a cancer and suboptimal application of targeted therapies. We here combined two related techniques to allow semiquantitative and localized in situ detection of specific transcript splice variants using single molecule molecular inversion probe (smMIP)-based next generation sequencing and padlock probe-based rolling circle amplification, respectively. We show highly specific padlock probe-based multiplex detection of MET, MET^Δ7-8 and MET^Δ14 transcripts, lacking exons 7-8 and exon 14 respectively, and of EGFR and the auto-active EGFRvIII, lacking exons 2-7. The combination of quantitative transcript variant detection with smMIPs and transcript localization using padlock probes can be used for detection of oncogenic transcripts on the single-cell level, allowing study of tumour heterogeneity. Visualization of tumour heterogeneity can shed light on the biology underlying drug resistance and potentially improve targeted therapeutics.

MYC Mediates Large Oncosome-Induced Fibroblast Reprogramming in Prostate Cancer

Communication between cancer cells and the tumor microenvironment results in the modulation of complex signaling networks that facilitate tumor progression. Here, we describe a new mechanism of intercellular communication originating from large oncosomes (LO), which are cancer cell-derived, atypically large (1-10 μm) extracellular vesicles (EV). We demonstrate that, in the context of prostate cancer, LO harbor sustained AKT1 kinase activity, nominating them as active signaling platforms. Active AKT1 was detected in circulating EV from the plasma of metastatic prostate cancer patients and was LO specific. LO internalization induced reprogramming of human normal prostate fibroblasts as reflected by high levels of α-SMA, IL6, and MMP9. In turn, LO-reprogrammed normal prostate fibroblasts stimulated endothelial tube formation in vitro and promoted tumor growth in mice. Activation of stromal MYC was critical for this reprogramming and for the sustained cellular responses elicited by LO, both in vitro and in vivo in an AKT1-dependent manner. Inhibition of LO internalization prevented activation of MYC and impaired the tumor-supporting properties of fibroblasts. Overall, our data show that prostate cancer-derived LO powerfully promote establishment of a tumor-supportive environment by inducing a novel reprogramming of the stroma. This mechanism offers potential alternative options for patient treatment. Cancer Res; 77(9); 2306-17. ©2017 AACR.

Extracellular vesicles in lung cancer-From bench to bedside

Lung cancer is the leading cause of cancer-related deaths worldwide. Despite significant advances in lung cancer research and novel therapies, a better understanding of the disease is crucially needed to facilitate early detection and appropriate diagnoses and to improve treatment outcomes. Extracellular vesicles (EVs), including exosomes, microvesicles, and apoptotic bodies, are released from all tested cell types and modulate cell-cell communication. EVs transfer a wide variety of molecules, such as proteins, messenger RNAs and microRNAs. Emerging data suggest that EVs play an important role in lung cancer pathogenesis and may have potential as biomarkers and therapeutics. Here, we review current research on EVs in lung cancer.

Extracellular Vesicles Exploit Viral Entry Routes for Cargo Delivery

Extracellular vesicles (EVs) have emerged as crucial mediators of intercellular communication, being involved in a wide array of key biological processes. Eukaryotic cells, and also bacteria, actively release heterogeneous subtypes of EVs into the extracellular space, where their contents reflect their (sub)cellular origin and the physiologic state of the parent cell. Within the past 20 years, presumed subtypes of EVs have been given a rather confusing diversity of names, including exosomes, microvesicles, ectosomes, microparticles, virosomes, virus-like particles, and oncosomes, and these names are variously defined by biogenesis, physical characteristics, or function. The latter category, functions, in particular the transmission of biological signals between cells in vivo and how EVs control biological processes, has garnered much interest. EVs have pathophysiological properties in cancer, neurodegenerative disorders, infectious disease, and cardiovascular disease, highlighting possibilities not only for minimally invasive diagnostic applications but also for therapeutic interventions, like macromolecular drug delivery. Yet, in order to pursue therapies involving EVs and delivering their cargo, a better grasp of EV targeting is needed. Here, we review recent progress in understanding the molecular mechanisms underpinning EV uptake by receptor-ligand interactions with recipient cells, highlighting once again the overlap of EVs and viruses. Despite their highly heterogeneous nature, EVs require common viral entry pathways, and an unanticipated specificity for cargo delivery is being revealed. We discuss the challenges ahead in delineating specific roles for EV-associated ligands and cellular receptors.

Cetuximab treatment alters the content of extracellular vesicles released from tumor cells

AIM

Extracellular vesicles (EVs) are attractive candidates for biomarker research, because their content reflects the parental cell status. This study aimed to examine whether tumor cell derived EVs mirrored the cellular changes caused by treatment with cetuximab, a therapeutic antibody that blocks activation of EGF receptor (EGFR).

MATERIALS & METHODS

A-431 cells were treated with cetuximab for 48 h. EVs were isolated using differential centrifugation and protein content was analyzed using western blotting.

RESULTS

EV levels of EGFR and phospho-EGFR were reduced after cetuximab treatment, reflecting similar changes in the parental cells. In addition, cetuximab was found associated with EVs.

CONCLUSION

EVs could serve as biomarkers to monitor cetuximab treatment. Association of cetuximab with EVs might influence its behavior.