Exosomes: potential for early detection in pancreatic cancer

Surface Proteome of Extracellular Vesicles and Correlation Analysis Reveal Breast Cancer Biomarkers

Breast cancer (BC) is the second most frequently diagnosed cancer and accounts for approximately 25% of new cancer cases in Canadian women. Using biomarkers as a less-invasive BC diagnostic method is currently under investigation but is not ready for practical application in clinical settings. During the last decade, extracellular vesicles (EVs) have emerged as a promising source of biomarkers because they contain cancer-derived proteins, RNAs, and metabolites. In this study, EV proteins from small EVs (sEVs) and medium EVs (mEVs) were isolated from BC MDA-MB-231 and MCF7 and non-cancerous breast epithelial MCF10A cell lines and then analyzed by two approaches: global proteomic analysis and enrichment of EV surface proteins by Sulfo-NHS-SS-Biotin labeling. From the first approach, proteomic profiling identified 2459 proteins, which were subjected to comparative analysis and correlation network analysis. Twelve potential biomarker proteins were identified based on cell line-specific expression and filtered by their predicted co-localization with known EV marker proteins, CD63, CD9, and CD81. This approach resulted in the identification of 11 proteins, four of which were further investigated by Western blot analysis. The presence of transmembrane serine protease matriptase (ST14), claudin-3 (CLDN3), and integrin alpha-7 (ITGA7) in each cell line was validated by Western blot, revealing that ST14 and CLDN3 may be further explored as potential EV biomarkers for BC. The surface labeling approach enriched proteins that were not identified using the first approach. Ten potential BC biomarkers (Glutathione S-transferase P1 (GSTP1), Elongation factor 2 (EEF2), DEAD/H box RNA helicase (DDX10), progesterone receptor (PGR), Ras-related C3 botulinum toxin substrate 2 (RAC2), Disintegrin and metalloproteinase domain-containing protein 10 (ADAM10), Aconitase 2 (ACO2), UTP20 small subunit processome component (UTP20), NEDD4 binding protein 2 (N4BP2), Programmed cell death 6 (PDCD6)) were selected from surface proteins commonly identified from MDA-MB-231 and MCF7, but not identified in MCF10A EVs. In total, 846 surface proteins were identified from the second approach, of which 11 were already known as BC markers. This study supports the proposition that Evs are a rich source of known and novel biomarkers that may be used for non-invasive detection of BC. Furthermore, the presented datasets could be further explored for the identification of potential biomarkers in BC.

Sex differences in the transcriptome of extracellular vesicles secreted by fetal neural stem cells and effects of chronic alcohol exposure

BACKGROUND

Prenatal alcohol (ethanol) exposure (PAE) results in brain growth restriction, in part, by reprogramming self-renewal and maturation of fetal neural stem cells (NSCs) during neurogenesis. We recently showed that ethanol resulted in enrichment of both proteins and pro-maturation microRNAs in sub-200-nm-sized extracellular vesicles (EVs) secreted by fetal NSCs. Moreover, EVs secreted by ethanol-exposed NSCs exhibited diminished efficacy in controlling NSC metabolism and maturation. Here we tested the hypothesis that ethanol may also influence the packaging of RNAs into EVs from cell-of-origin NSCs.

METHODS

Sex-specified fetal murine iso-cortical neuroepithelia from three separate pregnancies were maintained ex vivo, as neurosphere cultures to model the early neurogenic niche. EVs were isolated by ultracentrifugation from NSCs exposed to a dose range of ethanol. RNA from paired EV and cell-of-origin NSC samples was processed for ribosomal RNA-depleted RNA sequencing. Differential expression analysis and exploratory weighted gene co-expression network analysis (WGCNA) identified candidate genes and gene networks that were drivers of alterations to the transcriptome of EVs relative to cells.

RESULTS

The RNA content of EVs differed significantly from cell-of-origin NSCs. Biological sex contributed to unique transcriptome variance in EV samples, where > 75% of the most variant transcripts were also sex-variant in EVs but not in cell-of-origin NSCs. WGCNA analysis also identified sex-dependent enrichment of pathways, including dopamine receptor binding and ectoderm formation in female EVs and cell-substrate adhesion in male EVs, with the top significant DEGs from differential analysis of overall individual gene expressions, i.e., Arhgap15, enriched in female EVs, and Cenpa, enriched in male EVs, also serving as WCGNA hub genes of sex-biased EV WGCNA clusters. In addition to the baseline RNA content differences, ethanol exposure resulted in a significant dose-dependent change in transcript expression in both EVs and cell-of-origin NSCs that predominantly altered sex-invariant RNAs. Moreover, at the highest dose, ~ 73% of significantly altered RNAs were enriched in EVs, but depleted in NSCs.

CONCLUSIONS

The EV transcriptome is distinctly different from, and more sex-variant than, the transcriptome of cell-of-origin NSCs. Ethanol, a common teratogen, results in dose-dependent sorting of RNA transcripts from NSCs to EVs which may reprogram the EV-mediated endocrine environment during neurogenesis.

Dose-related shifts in proteome and function of extracellular vesicles secreted by fetal neural stem cells following chronic alcohol exposure

Accumulating evidence indicates that extracellular vesicles (EVs) mediate endocrine functions and also pathogenic effects of neurodevelopmental perturbagens like ethanol. We performed mass-spectrometry on EVs secreted by fetal murine cerebral cortical neural stem cells (NSCs), cultured ex-vivo as sex-specific neurosphere cultures, to identify overrepresented proteins and signaling pathways in EVs relative to parental NSCs in controls, and following exposure of parental NSCs to a dose range of ethanol. EV proteomes differ substantially from parental NSCs, and though EVs sequester proteins across sub-cellular compartments, they are enriched for distinct morphogenetic signals including the planar cell polarity pathway. Ethanol exposure favored selective protein sequestration in EVs and depletion in parental NSCs, and also resulted in dose-independent overrepresentation of cell-cycle and DNA replication pathways in EVs as well as dose-dependent overrepresentation of rRNA processing and mTor stress pathways. Transfer of untreated EVs to naïve cells resulted in decreased oxidative metabolism and S-phase, while EVs derived from ethanol-treated NSCs exhibited diminished effect. Collectively, these data show that NSCs secrete EVs with a distinct proteome that may have a general growth-inhibitory effect on recipient cells. Moreover, while ethanol results in selective transfer of proteins from NSCs to EVs, the efficacy of these exposure-derived EVs is diminished.

Proteomes of Extracellular Vesicles From Pancreatic Cancer Cells and Cancer-Associated Fibroblasts

OBJECTIVES

Extracellular vesicles (EVs) are lipid bound vesicles secreted by cells into the extracellular environment. Studies have implicated EVs in cell proliferation, epithelial-mesenchymal transition, metastasis, angiogenesis, and mediating the interaction of tumor cells and microenvironment. A systematic characterization of EVs from pancreatic cancer cells and cancer-associated fibroblasts (CAFs) would be valuable for studying the roles of EV proteins in pancreatic tumorigenesis.

METHODS

Proteomic and functional analyses were applied to characterize the proteomes of EVs released from 5 pancreatic cancer lines, 2 CAF cell lines, and a normal pancreatic epithelial cell line (HPDE).

RESULTS

More than 1400 nonredundant proteins were identified in each EV derived from the cell lines. The majority of the proteins identified in the EVs from the cancer cells, CAFs, and HPDE were detected in all 3 groups, highly enriched in the biological processes of vesicle-mediated transport and exocytosis. Protein networks relevant to pancreatic tumorigenesis, including epithelial-mesenchymal transition, complement, and coagulation components, were significantly enriched in the EVs from cancer cells or CAFs.

CONCLUSIONS

These findings support the roles of EVs as a potential mediator in transmitting epithelial-mesenchymal transition signals and complement response in the tumor microenvironment and possibly contributing to coagulation defects related to cancer development.

Circulating Exosome Cargoes Contain Functionally Diverse Cancer Biomarkers: From Biogenesis and Function to Purification and Potential Translational Utility

Although diagnostic and therapeutic treatments of cancer have tremendously improved over the past two decades, the indolent nature of its symptoms has made early detection challenging. Thus, inter-disciplinary (genomic, transcriptomic, proteomic, and lipidomic) research efforts have been focused on the non-invasive identification of unique "silver bullet" cancer biomarkers for the design of ultra-sensitive molecular diagnostic assays. Circulating tumor biomarkers, such as CTCs and ctDNAs, which are released by tumors in the circulation, have already demonstrated their clinical utility for the non-invasive detection of certain solid tumors. Considering that exosomes are actively produced by all cells, including tumor cells, and can be found in the circulation, they have been extensively assessed for their potential as a source of circulating cell-specific biomarkers. Exosomes are particularly appealing because they represent a stable and encapsulated reservoir of active biological compounds that may be useful for the non-invasive detection of cancer. T biogenesis of these extracellular vesicles is profoundly altered during carcinogenesis, but because they harbor unique or uniquely combined surface proteins, cancer biomarker studies have been focused on their purification from biofluids, for the analysis of their RNA, DNA, protein, and lipid cargoes. In this review, we evaluate the biogenesis of normal and cancer exosomes, provide extensive information on the state of the art, the current purification methods, and the technologies employed for genomic, transcriptomic, proteomic, and lipidomic evaluation of their cargoes. Our thorough examination of the literature highlights the current limitations and promising future of exosomes as a liquid biopsy for the identification of circulating tumor biomarkers.

Small extracellular vesicles (exosomes) and their cargo in pancreatic cancer: Key roles in the hallmarks of cancer

Pancreatic cancer (PC) is a devastating disease, offering poor mortality rates for patients. The current challenge being faced is the inability to diagnose patients in a timely manner, where potentially curative resection provides the best chance of survival. Recently, small/nanosized extracellular vesicles (sEVs), including exosomes, have gained significant preclinical and clinical attention due to their emerging roles in cancer progression and diagnosis. Extracellular vesicles (EVs) possess endogenous properties that offer stability and facilitate crossing of biological barriers for delivery of molecular cargo to cells, acting as a form of intercellular communication to regulate function and phenotype of recipient cells. This review provides an overview of the role of EVs, their subtypes and their oncogenic cargo (as characterised by targeted studies as well as agnostic '-omics' analyses) in the pathobiology of pancreatic cancer. The discussion covers the progress of 'omics technology' that has enabled elucidation of the molecular mechanisms that mediate the role of EVs and their cargo in pancreatic cancer progression.

Serum exosomal miR-451a acts as a candidate marker for pancreatic cancer

OBJECTIVES

The aim of this study was to explore the diagnostic efficiency of serum exosomal miR-451a as a novel biomarker for pancreatic cancer.

METHODS

Serum samples were collected prior to treatment. First, we analyzed microRNA (miRNA) profiles in serum exosomes from eight pancreatic cancer patients and eight healthy volunteers. We then validated the usefulness of the selected exosomal miRNAs as biomarkers in another 191 pancreatic cancer patients, 95 pancreatic benign disease (PB) patients, and 90 healthy controls.

RESULTS

The expression of miR-451a in serum-derived exosomes from pancreatic cancer patients was significantly upregulated compared with those from PB patients and healthy individuals. Serum exosomal miR-451a showed excellent diagnostic power in identifying pancreatic cancer patients. In addition, exosomal miR-451a showed a significant association with clinical stage and distant metastasis in pancreatic cancer, and the expression level of serum exosomal miR-451a was sensitive to therapy and relapse.

CONCLUSIONS

Serum exosomal miR-451a might serve as a novel diagnostic marker for pancreatic cancer.

Characteristics and Clinical Application of Extracellular Vesicle-Derived DNA

Extracellular vesicles (EVs) carry RNA, proteins, lipids, and diverse biomolecules for intercellular communication. Recent studies have reported that EVs contain double-stranded DNA (dsDNA) and oncogenic mutant DNA. The advantage of EV-derived DNA (EV DNA) over cell-free DNA (cfDNA) is the stability achieved through the encapsulation in the lipid bilayer of EVs, which protects EV DNA from degradation by external factors. The existence of DNA and its stability make EVs a useful source of biomarkers. However, fundamental research on EV DNA remains limited, and many aspects of EV DNA are poorly understood. This review examines the known characteristics of EV DNA, biogenesis of DNA-containing EVs, methylation, and next-generation sequencing (NGS) analysis using EV DNA for biomarker detection. On the basis of this knowledge, this review explores how EV DNA can be incorporated into diagnosis and prognosis in clinical settings, as well as gene transfer of EV DNA and its therapeutic potential.

Exosomal microRNA in Pancreatic Cancer Diagnosis, Prognosis, and Treatment: From Bench to Bedside

Simple Summary

Pancreatic cancer is the fourth leading cause of cancer death in the United States and over 90% of the patients suffer from pancreatic ductal adenocarcinoma (PDAC). PDAC is the most lethal gastrointestinal malignancies and only 10% of the people survive more than 5 years, therefore, novel diagnostic, prognostic, and therapeutic strategies are an immediate necessity. Studies have demonstrated microRNAs in bodily fluids that are bound with membranes (exosomes) can act as stable biomarkers both for disease development and metastasis. The diagnostic, prognostic, as well as therapeutic roles of exosomal microRNAs in pancreatic cancer have been discussed in this review.

Abstract

Pancreatic cancer is the fourth leading cause of cancer death among men and women in the United States, and pancreatic ductal adenocarcinoma (PDAC) accounts for more than 90% of pancreatic cancer cases. PDAC is one of the most lethal gastrointestinal malignancies with an overall five-year survival rate of ~10%. Developing effective therapeutic strategies against pancreatic cancer is a great challenge. Novel diagnostic, prognostic, and therapeutic strategies are an immediate necessity to increase the survival of pancreatic cancer patients. So far, studies have demonstrated microRNAs (miRNAs) as sensitive biomarkers because of their significant correlation with disease development and metastasis. The miRNAs have been shown to be more stable inside membrane-bound vesicles in the extracellular environment called exosomes. Varieties of miRNAs are released into the body fluids via exosomes depending on the normal physiological or pathological conditions of the body. In this review, we discuss the recent findings on the diagnostic, prognostic, and therapeutic roles of exosomal miRNAs in pancreatic cancer.

A Protocol for Cancer-Related Mutation Detection on Exosomal DNA in Clinical Application

Background

Recently, some genomic mutations in exosomal DNA have been found to be related to disease progress and clinical outcomes of patients in several cancers. Unfortunately, the methods for exosome isolation and exosomal DNA analysis are still lack of relevant research to ensure their optimal performance and the comparability. Here we aim to establish a protocol for cancer-related mutation detection on exosomal DNA in clinical application.

Methods

Taking KRAS mutation in pancreatic cancer as an example, we tested whether the types of blood samples, the potential factors in the courses of exosome isolation and exosomal DNA preparation, as well as the detail in mutation detection by droplet digital PCR (ddPCR) could influence the exosomal DNA analysis.

Results

We found that the concentration of exosomal DNA from serum was higher than that from plasma, whereas the mutant allele fraction (MAF) of KRAS in serum-derived exosomal DNA was obviously lower. The membrane-based method for exosome isolation showed no evident difference in both exosomal DNA yield and KRAS MAF from the classical ultracentrifugation method. DNase I pretreatment on exosomes could remove the wild-type DNA outside of exosomes and increase the KRAS MAF. PBS might interfere with the effect of DNase I and should not be recommended as resuspension buffer for exosomes if the subsequent experiments would be done with exosomal DNA. Besides, the denaturation of exosomal DNA before droplet generation during ddPCR could effectively improve the total KRAS copy number and mutation-positive droplet number.

Conclusion

This study provides some methodological evidences for the selection of the optimal experimental conditions in exosomal DNA analysis. We also suggest a protocol for mutation detection on exosomal DNA, which might be suitable for the clinical testing and could be helpful to the comparison of results from different laboratories.

The involvement of exosomes in the diagnosis and treatment of pancreatic cancer

At the moment, pancreatic cancer is among the deadliest gastrointestinal diseases, and pancreatic cancer growth is a complex biological process that is based on different kinds of genes. Exosomes are extracellular vesicles containing microRNAs (miRNAs), messenger RNA (mRNA), and proteins, they act as the most prominent mediator of intercellular communication, and they regulate, instruct, and re-educate their surrounding microenvironment and target specific organs. Due to accumulative evidence proved that exosomes are involved in metastasis, cell proliferation, EMT, angiogenesis, and TME of pancreatic cancer, exosomes are crucial potential candidates to detect pancreatic cancer early. This review aims to convey the current understanding of the main functions employed by exosomes in early diagnosis and treatment of pancreatic cancer.

Small Extracellular Vesicles Released from Ovarian Cancer Spheroids in Response to Cisplatin Promote the Pro-Tumorigenic Activity of Mesenchymal Stem Cells

Despite the different strategies used to treat ovarian cancer, around 70% of women/patients eventually fail to respond to the therapy. Cancer stem cells (CSCs) play a role in the treatment failure due to their chemoresistant properties. This capacity to resist chemotherapy allows CSCs to interact with different components of the tumor microenvironment, such as mesenchymal stem cells (MSCs), and thus contribute to tumorigenic processes. Although the participation of MSCs in tumor progression is well understood, it remains unclear how CSCs induce the pro-tumorigenic activity of MSCs in response to chemotherapy. Small extracellular vesicles, including exosomes, represent one possible way to modulate any type of cell. Therefore, in this study, we evaluate if small extracellular vesicle (sEV) derived from ovarian cancer spheroids (OCS), which are enriched in CSCs, can modify the activity of MSCs to a pro-tumorigenic phenotype. We show that sEV released by OCS in response to cisplatin induce an increase in the migration pattern of bone marrow MSCs (BM-MSCs) and the secretion interleukin-6 (IL-6), interleukin-8 (IL-8), and vascular endothelial growth factor A (VEGFA). Moreover, the factors secreted by BM-MSCs induce angiogenesis in endothelial cells and the migration of low-invasive ovarian cancer cells. These findings suggest that cisplatin could modulate the cargo of sEV released by CSCs, and these exosomes can further induce the pro-tumorigenic activity of MSCs.

Ethanol Exposure Increases miR-140 in Extracellular Vesicles: Implications for Fetal Neural Stem Cell Proliferation and Maturation

BACKGROUND

Neural stem cells (NSCs) generate most of the neurons of the adult brain in humans, during the mid-first through second-trimester period. This critical neurogenic window is particularly vulnerable to prenatal alcohol exposure, which can result in diminished brain growth. Previous studies showed that ethanol (EtOH) exposure does not kill NSCs, but, rather, results in their depletion by influencing cell cycle kinetics and promoting aberrant maturation, in part, by altering NSC expression of key neurogenic miRNAs. NSCs reside in a complex microenvironment rich in extracellular vesicles, shown to traffic miRNA cargo between cells.

METHODS

We profiled the miRNA content of extracellular vesicles from control and EtOH-exposed ex vivo neurosphere cultures of fetal NSCs. We subsequently examined the effects of one EtOH-sensitive miRNA, miR-140-3p, on NSC growth, survival, and maturation.

RESULTS

EtOH exposure significantly elevates levels of a subset of miRNAs in secreted extracellular vesicles. Overexpression of one of these elevated miRNAs, miR-140-3p, and its passenger strand relative, miR-140-5p, significantly increased the proportion of S-phase cells while decreasing the proportion of G₀ /G₁ cells compared to controls. In contrast, while miR-140-3p knockdown had minimal effects on the proportion of cells in each phase of the cell cycle, knockdown of miR-140-5p significantly decreased the proportion of cells in G₂ /M phase. Furthermore, miR-140-3p overexpression, during mitogen-withdrawal-induced NSC differentiation, favors astroglial maturation at the expense of neural and oligodendrocyte differentiation.

CONCLUSIONS

Collectively, the dysregulated miRNA content of extracellular vesicles following EtOH exposure may result in aberrant neural progenitor cell growth and maturation, explaining brain growth deficits associated with prenatal alcohol exposure.

Increased systemic immune-inflammation index independently predicts poor survival for hormone receptor-negative, HER2-positive breast cancer patients

Purpose: We sought to examine the role of pretreatment systemic immune-inflammation index (SII) in hormone receptor-negative, human epidermal growth factor receptor 2+ (HER2+) breast cancer patients.

Patients and methods: 155 HER2+ patients treated in our hospital from September 3, 2002, to September 21, 2012, were retrospectively enrolled. SII was established as neutrophil x platelet/lymphocyte counts. The median value of SII was used as cut-off value. We used the Kaplan-Meier method to evaluate the overall survival (OS), disease-free survival (DFS), distant metastasis-free survival (DMFS). To comparatively evaluate the survival rates between patients from two groups, we used the log-rank test. For identifying independent factors of prognosis, we used the Cox regression model, applying multivariate statistics.

Results: Analyses show that HER2+ patients with high and low SII had median DFS of 15.1 and 31.5 months, respectively (P<0.001), while the median DMFS in HER2+ patients with high SII was 18.4 and in patients with low SII was 33.0 months (P=0.001), and the median OS were 54.5 and 71.1 months respectively in high and low SII patients, respectively (P=0.002). Multivariate analysis had revealed increased SII independently linked to poor DFS (HR =1.46, 95% CI: 1.01–2.11, P=0.045). The difference between SII and DMFS bore no statistical significance. (HR =1.40, 95% CI: 0.96–2.03, P=0.078), while high SII independently predicted short OS (HR =1.51, 95% CI: 1.02–2.25, P=0.038).

Conclusion: Our findings suggest that increased SII independently predicts poor survival for hormone receptor-negative, HER2+ breast cancer patients. Prospective studies are, however, required to confirm the role of SII in the prognosis of patients with HER2+ before clinical use.

Clinical significance of exosomal miRNAs and proteins in three human cancers with high mortality in China

Cancer is the second leading cause of mortality worldwide. More importantly, the mortality rates for cancer are increasing. In China, lung cancer, liver cancer and gastric cancer are the top three leading causes of mortality in males, whereas lung cancer, gastric cancer and liver cancer are ranked the top three causes of mortality in females. Exosomes are extracellular vesicles that are produced and released by many different cells; these vesicles have a size range between 30 and 100 nm in diameter, and contain a lipid bilayer. Exosomes exist in various bodily fluids, contain plentiful amounts of nucleic acids and proteins, and shuttle these materials between cells to mediate the development of cancers. The present review summarizes the composition of exosomes and methods for their isolation and then intensively highlights the latest findings on the contributions of exosomal microRNAs (miRNAs) and proteins to lung cancer, liver cancer and gastric cancer. Taken together, exosomal miRNAs and proteins may be used as noninvasive, novel biomarkers for cancer diagnosis, prognosis or precision treatment owing to their ability to promote tumor progression and metastasis, and their ability to regulate the immune response and tumor cell sensitivity to chemotherapy drugs.

Clinical utilization of serum- or plasma-based miRNAs as early detection biomarkers for pancreatic cancer: A meta-analysis up to now

BACKGROUND

Pancreatic cancer (PC) is a lethal disease, however current screening methods unable to achieve early diagnosis. Blood-based microRNAs (miRNAs) are promising molecular biomarkers for detecting PC. This meta-analysis summaries studies identifying serum- or plasma-based miRNAs dysregulated in PC patients compared to non-PC cases to evaluate their diagnostic accuracy for characterizing PC.

METHODS

A systematically reviews and meta-analysis of published studies was conducted to compare the serum or plasma miRNAs expressions between PC patients and non-PC cases. Summary estimates for sensitivity, specificity, along with other measures of accuracy of miRNAs in the diagnosis of PC were pooled using the random-effects model. I and Q tests were used to assess the heterogeneity of included studies. The Spearman test was used to analyze the threshold effect.

RESULTS

Twenty-seven eligible studies were identified after electronic search and literature selection. For single miRNA dysregulation, 32 miRNAs were found to be upregulated in PC patients, and 5 miRNAs were downregulated. Four studies identified a 2-miRNA panel, and 10 studies identified a panel consisting of 3 or more miRNAs which were used to detect PC patients. Additionally, 8 studies combined miRNA panels and carbohydrate antigen 19-9 (CA 19-9) to diagnose PC. The pooled sensitivities for these 4 groups were 0.77 to 0.85, and specificities were 0.70 to 0.87. The highest area under the curve (AUC), 0.9308, was identified using 2 miRNA panels with sensitivity and specificity of 0.79 (0.74-0.83) and 0.85 (0.81-0.89), respectively. There was great heterogeneity of these 4 miRNA groups. Results of Spearman test revealed that there existed a threshold effect on single miRNA group (r=-0.437, P=.001), and none of the other groups (P all>.05).

CONCLUSIONS

Serum- or plasma-based miRNAs are capable of distinguishing PC from non-PC with relatively high sensitivity and specificity. In future, miRNAs may be used as promising diagnostic biomarkers for detection of PC.

Pancreatic cancer and associated exosomes

Pancreatic cancers with poor prognosis are highly malignant, readily metastatic and of immune tolerance, mainly due to delayed detection. The metastatic progression and immune tolerance of pancreatic cancer is greatly attributed to the intercellular communication. However, exosomes are deemed to be the most important tool of intercellular communicators. Thus, we present a review of pancreatic cancer and exosomes in this article. We intensively summarize the progress of early pancreatic cancer and the relationship of the proliferation, progression and metastasis of pancreatic cancer and pancreatic cancer-derived exosomes, and propose new ideas of the study of pancreatic cancer.

High-Performance Chemical Isotope Labeling Liquid Chromatography Mass Spectrometry for Exosome Metabolomics

Circulating exosomes in bodily fluids such as blood are being actively studied as a rich source of chemical biomarkers for cancer diagnosis and monitoring. Although nucleic acid analysis is a primary tool for the discovery of circulating biomarkers in exosomes, metabolomics holds the potential of expanding the chemical diversity of biomarkers that may be easy and rapid to detect. However, only trace amounts of exosomes can be isolated from a small volume of patient blood, and thus a very sensitive technique is required to analyze the metabolome of exosomes. In this report, we present a workflow that involves multiple cycles of ultracentrifugation for exosome isolation using a starting material of 2 mL of human serum, freeze-thaw-cycles in 50% methanol/water for exosome lysis and metabolite extraction, differential chemical isotope labeling (CIL) of metabolites for enhancing liquid chromatography (LC) separation and improving mass spectrometry (MS) detection, and nanoflow LC-MS (nLC-MS) with captivespray for analysis. As a proof-of-principle, we used dansylation labeling to analyze the amine- and phenol-submetabolomes in two sets of exosome samples isolated from the blood samples of five pancreatic cancer patients before and after chemotherapy treatment. The average number of peak pairs or metabolites detected was 1964 ± 60 per sample for a total of 2446 peak pairs ( n = 10) in the first set and 1948 ± 117 per sample for a total of 2511 peak pairs ( n = 10) in the second set. There were 101 and 94 metabolites positively identified in the first and second set, respectively, and 1580 and 1590 peak pairs with accurate masses matching those of metabolites in the MyCompoundID metabolome database. Analyzing the mixtures of 12C-labeled individual exosome samples spiked with a 13C-labeled pooled sample which served as an internal standard allowed relative quantification of metabolomic changes of exosomes of blood samples collected before and after treatment.

Proteomic biomarkers in body fluids associated with pancreatic cancer

Pancreatic cancer (PC) is a highly malignant disease that represents the fourth leading cancer-related death worldwide. There has been very little improvement in survival rates over recent years, and surgical resection remains the only reliable curative approach. Factors that contribute to this dismal prognosis for PC include its rapid progression and invasion, the absence of specific symptoms, and the little impact of available chemotherapy. Importantly, the management of this malignancy is also limited by the lack of highly specific and sensitive biomarkers for its diagnosis and follow-up, and their identification is therefore considered a promising strategy to improve outcomes in these patients. Numerous translational studies have explored the usefulness of body fluids as a non-invasive source of PC-specific biomarkers, and innovations in proteomic methods and technologies have provided a myriad of protein biomarkers for different cancers. The adoption of a proteomic approach has improved understanding of the biology of PC and contributed to the potential identification of protein biomarkers for this disease. This review considers the most recent research efforts to develop novel proteomic biomarkers in body fluids for PC.

Role of exosomes in pancreatic cancer

Pancreatic cancer is one of the most lethal malignancies. Exosomes, which are released by multiple cell types, such as cancer cells, contain functional biomolecules (including proteins, nucleic acids and lipids) that can be horizontally delivered to recipient cells. Exosomes act as the most prominent mediator of intercellular communication and can regulate, instruct and re-educate their surrounding microenvironment and target specific organs. The present review performed an extensive search of multiple databases from 2005 to April 23 2017, for eligible literature relating to exosomes and their role in pancreatic cancer. With a focus on the latest findings for pancreatic cancer exosomes, their role in tumorigenesis was summarized, as well as their aggressive behaviors and their contribution to immunosuppression and therapy resistance in pancreatic cancer. In addition, the potential function of exosomes as novel diagnostic biomarkers is briefly discussed. Finally, we propose potential clinical applications for exosomes in pancreatic cancer.

Current Molecular and Genetic Aspects of Pancreatic Cancer, the Role of Metastasis Associated Proteins (MTA): A Review

Purpose/aim: To focus on current molecular and genetic aspects and MTA proteins, since pancreatic cancer is a lethal malignant with poor prognosis. Early diagnosis is essential step, contributing to potential curative resection.

MATERIALS AND METHODS

A PubMed search of relevant articles published up to August 2016 was performed to identify current information about pancreatic cancer regarding molecular biomarkers, with emphasis on carcinogenesis, novel therapeutic targets, and MTA proteins.

RESULTS

Understanding the mechanisms involved in the process of carcinogenesis at the molecular level and the recognition of various oncogenes has opened new horizons for both diagnosis and targeted therapy. Metastasis associated (MTA) proteins (MTA1, MTA2, MTA3) comprise a well-established family of biomarkers. The oncogene MTA1 and its expression product MTA1 protein are the most important and adequately studied in the current research. It defines the growth, local invasiveness, lymphatic spread, and metastatic capacity of various malignancies such as colorectal or gastric cancer including also pancreatic cancer. This protein is associated with malignant potential and biological behavior. Consequently, it could contribute to cancer detection since the first stages of carcinogenesis, as well as in prediction of its malignant differentiation grade. The pre-operative information of the possibility of lymph node involvement may also affect the attempt and the extent of curative resection and lymphadenectomy.

CONCLUSIONS

Carcinogenesis and implicated oncogenes, either activators or repressors, concentrate much research interest, as well as being useful as biomarkers and for targeted therapy. MTA proteins could become useful diagnostic and prognostic biomarkers in current management of pancreatic cancer.

Pancreatic Cancer Diagnosis and Management: Has the Time Come to Prick the Bubble?

Pancreatic cancer (PC) is associated with poor prognosis and very dismal survival rates. The most effective possibility of cure is tumor resection, which is only possible in about 15% of patients diagnosed at early stages of disease progression. Recent whole-genome sequencing studies pointed genetic alterations in 12 core signaling pathways in PC. These observations hint at the possibility that the initial mutation in PC might appear nearly 20 years before any symptoms occur, suggesting that a large window of opportunity may exist for early detection. Biomarkers with the potential to identify pre-neoplastic disease or very early stages of cancer are of great promise to improve patient survival. The concept of liquid biopsy refers to a minimally invasive sampling and analysis of liquid biomarkers that can be isolated from body fluids, primarily blood, urine and saliva. A myriad of circulating molecules may be useful as tumor markers, including cell-free DNA (cfDNA), cell-free RNA (cfRNA), circulating tumor cells (CTC), circulating tumor proteins, and extracellular vesicles, more specifically exosomes. In this review, we discuss with more detail the potential role of exosomes in several aspects related to PC, from initiation to tumor progression and its applicability in early detection and treatment. Exosomes are small circulating extracellular vesicles of 50-150 nm in diameter released from the plasma membrane by almost all cells and exhibit some advantages over other biomarkers. Exosomes are central players of intercellular communication and they have been implicated in a series of biological process, including tumorigenesis, migration and metastasis. Several exosomal microRNAs and proteins have been observed to distinguish PC from benign pancreatic diseases and healthy controls. Besides their possible role in diagnosis, understanding exosomes functions in cancer has clarified the importance of microenvironment in PC progression as well as its influence in proliferation, metastasis and resistance to chemotherapy. Increasing knowledge on cancer exosomes provides valuable insights on new therapeutic targets and can potentially open new strategies to treat this disease. Continuous research is needed to ascertain the reliability of using exosomes and their content as potential biomarkers, so that, hopefully, in the near future, they will provide the opportunity for early diagnosis, treatment intervention and increase survival of PC patients.

Upregulated exosomic miR‑23b‑3p plays regulatory roles in the progression of pancreatic cancer

Pancreatic cancer (PC) is one of the most lethal malignances. Identification of biomarkers for early diagnosis of PC is a key imperative. MicroRNAs (miRNAs) have been shown to be valuable biomarkers in the context of several cancers. Exosomes refer to vesicles released by the tumor cells at the early stage of disease. Thus, detection of miRNA in exosomes can be used as a potential biomarker for PC. In this study, we profiled serum levels of miRNAs in patients with chronic pancreatitis (CP) and PC; the role of miR-23b-3p in PC progression was assessed in vitro. Additionally, we assessed, the expression of miR-23b-3p in exosomes isolated from serum samples and assessed the correlation between the expression of miR-23b-3p and carbohydrate antigen 19-9 (CA19-9). Three serum samples each were randomly selected from healthy controls (n=20), and patients with CP (n=18) and PC (n=16) for miRNA microarray profiling. The dysregulated miRNAs were confirmed using qRT-PCR. Four dysregulated miRNAs common to patients with CP and PC were identified on miRNA microarray analysis and confirmed by qRT-PCR. miR-23b-3p level was consistently higher in serum samples from PC patients as compared to those from healthy controls and CP patients (p<0.05). Overexpression of miR-23b-3p promoted proliferation, migration, and invasion capability of PC cells in vitro (p<0.05). Furthermore, miR-23b-3p was upregulated in exosomes of PC serum samples and the supernatant of pancreatic cancer cells (PANC-1), and the expression levels of miR-23b-3p were associated with those of serum CA19-9 levels. This study provides insights into the potential role of miR-23b-3p as a novel biomarker and target for treatment of PC.

Murine and human pancreatic tumor exosome recovery in mouse serum: Diagnostic and prognostic potential and target cell delivery

Exosomes (Exo), powerful intercellular communicators, are recovered in all body fluids, suggesting suitability for diagnosis and prognosis. Easy in vitro manipulation recommends Exo as drug vehicles. Aiming to consolidate diagnostic and therapeutic potential of Exo, we evaluated recovery and fate of tumor (TEX) and exogenous Exo in syngeneic and xenogeneic mice bearing a murine or a human pancreatic adenocarcinoma. A significant increase in serum (S)-TEX was observed 2 weeks after tumor cell application. Instead, S-TEX declined within 3-6 days after tumor excision. Intravenously injected dye-labeled TEX were rapidly cleared from the serum. Partly being degraded in the liver, the majority is taken-up by PBL, liver, bone marrow and lung cells. In the tumor-bearing host TEX persisted longer becoming enriched in tumor cells and metastatic organs. Accordingly, an antibody blockade of a TEX marker hampered disseminated tumor cell settlement in selected organs. In brief, a tumor marker panel appears suited for S-TEX recovery. In murine models, S-TEX are qualified for therapy control and follow-up studies. Despite rapid clearance from the serum, Exo uptake by host cells is most promising for tailored Exo as drug transporter.

Gender-specific differential expression of exosomal miRNA in synovial fluid of patients with osteoarthritis

The pathogenesis of osteoarthritis (OA) is poorly understood, and therapeutic approaches are limited to preventing progression of the disease. Recent studies have shown that exosomes play a vital role in cell-to-cell communication, and pathogenesis of many age-related diseases. Molecular profiling of synovial fluid derived exosomal miRNAs may increase our understanding of OA progression and may lead to the discovery of novel biomarkers and therapeutic targets. In this article we report the first characterization of exosomes miRNAs from human synovial fluid. The synovial fluid exosomes share similar characteristics (size, surface marker, miRNA content) with previously described exosomes in other body fluids. MiRNA microarray analysis showed OA specific exosomal miRNA of male and female OA. Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis identified gender-specific target genes/signaling pathways. These pathway analyses showed that female OA specific miRNAs are estrogen responsive and target TLR (toll-like receptor) signaling pathways. Furthermore, articular chondrocytes treated with OA derived extracellular vesicles had decreased expression of anabolic genes and elevated expression of catabolic and inflammatory genes. In conclusion, synovial fluid exosomal miRNA content is altered in patients with OA and these changes are gender specific.

Mining Exosomal Genes for Pancreatic Cancer Targets

BACKGROUND

Exosomes, cell-derived vesicles encompassing lipids, DNA, proteins coding genes and noncoding RNAs (ncRNAs) are present in diverse body fluids. They offer novel biomarker and drug therapy potential for diverse diseases, including cancer.

MATERIALS AND METHODS

Using gene ontology, exosomal genes database and GeneCards metadata analysis tools, a database of cancer-associated protein coding genes and ncRNAs (n=2,777) was established. Variant analysis, expression profiling and pathway mapping were used to identify putative pancreatic cancer exosomal gene candidates.

RESULTS

Five hundred and seventy-five protein-coding genes, 26 RNA genes and one pseudogene directly associated with pancreatic cancer were identified in the study. Nine open reading frames (ORFs) encompassing enzymes, apoptosis and transcriptional regulators, and secreted factors and five cDNAs (enzymes) emerged from the analysis. Among the ncRNA class, 26 microRNAs (miRs), one pseudogene, one long noncoding RNA (LNC) and one antisense gene were identified. Furthermore, 22 exosome-associated protein-coding targets (a cytokine, enzymes, membrane glycoproteins, receptors, and a transporter) emerged as putative leads for pancreatic cancer therapy. Seven of these protein-coding targets are FDA-approved and the drugs-based on these could provide repurposing opportunities for pancreatic cancer.

CONCLUSION

The database of exosomal genes established in this study provides a framework for developing novel biomarkers and drug therapy targets for pancreatic cancer.

High prevalence of mutant KRAS in circulating exosome-derived DNA from early-stage pancreatic cancer patients

Background

Exosomes arise from viable cancer cells and may reflect a different biology than circulating cell-free DNA (cfDNA) shed from dying tissues. We compare exosome-derived DNA (exoDNA) to cfDNA in liquid biopsies of patients with pancreatic ductal adenocarcinoma (PDAC).

Patients and methods

Patient samples were obtained between 2003 and 2010, with clinically annotated follow up to 2015. Droplet digital PCR was performed on exoDNA and cfDNA for sensitive detection of KRAS mutants at codons 12/13. A cumulative series of 263 individuals were studied, including a discovery cohort of 142 individuals: 68 PDAC patients of all stages; 20 PDAC patients initially staged with localized disease, with blood drawn after resection for curative intent; and 54 age-matched healthy controls. A validation cohort of 121 individuals (39 cancer patients and 82 healthy controls) was studied to validate KRAS detection rates in early-stage PDAC patients. Primary outcome was circulating KRAS status as detected by droplet digital PCR. Secondary outcomes were disease-free and overall survival.

Results

KRAS mutations in exoDNA, were identified in 7.4%, 66.7%, 80%, and 85% of age-matched controls, localized, locally advanced, and metastatic PDAC patients, respectively. Comparatively, mutant KRAS cfDNA was detected in 14.8%, 45.5%, 30.8%, and 57.9% of these individuals. Higher exoKRAS MAFs were associated with decreased disease-free survival in patients with localized disease. In the validation cohort, mutant KRAS exoDNA was detected in 43.6% of early-stage PDAC patients and 20% of healthy controls.

Conclusions

Exosomes are a distinct source of tumor DNA that may be complementary to other liquid biopsy DNA sources. A higher percentage of patients with localized PDAC exhibited detectable KRAS mutations in exoDNA than previously reported for cfDNA. A substantial minority of healthy samples demonstrated mutant KRAS in circulation, dictating careful consideration and application of liquid biopsy findings, which may limit its utility as a broad cancer-screening method.

Helicobacter pylori infection, H19 and LINC00152 expression in serum and risk of gastric cancer in a Chinese population

Gastric cancer (GC) is a consequence of multifactorial and multistep processes. Helicobacter pylori (H. pylori) infection plays a crucial role in gastric carcinogenesis. Long non-coding RNAs (lncRNAs) have shown great potential as powerful cancer biomarkers. To investigate the possible roles of lncRNAs and H. pylori infection in GC development, we measured expression levels of three lncRNAs (H19, LINC00152, uc001lsz) in serum from a total of 285 Chinese participants using reverse transcription-quantitative polymerase chain reaction. We found significant associations between high expression of both H19 and LINC00152 in serum and increased risk of GC; the adjusted OR for H19 was 2.17 (95% CI: 1.21-3.88), and for LINC00152 was 2.09 (95% CI: 1.18-3.70). Further analyses indicated an elevated risk of GC in subjects with both high H19 expression and H. pylori infection (OR: 13.75, 95% CI: 4.75-39.84). Significant joint effect between LINC00152 and H. pylori infection on risk of GC was also found (OR: 17.49, 95% CI: 4.78-63.92). Serum H19 and LINC00152 may serve as potential biomarkers for diagnosis of GC, particularly for those with H. pylori infection.