Tumor-originated exosomal lncUEGC1 as a circulating biomarker for early-stage gastric cancer

Current advancement of exosomes as biomarkers for cancer diagnosis and forecasting

Exosomes are normal vesicles produced in the late endosomes of a cell. They are secreted by cells and play a role in cell-to-cell contact. They are an invaluable aid in cancer diagnosis as they include miRNA, proteins and lncRNAs. Depending on the function of these constituents in cancer, the expression of exosome constituents can be upregulated or downregulated in cancer. Exosomes provide high concentration and protective environment for their cargo, thereby making them superior targets for cancer diagnosis. It has recently been documented that exosomes modulate cell-cell connectivity by molecules included in the exosomes, leading to the maintenance of tissue homeostasis. In addition, exosomes released from cancer cells are implicated in the development of cancer. Data on the role of exosomes in cancer will thus enhance the effectiveness of new diagnostic and therapeutic approaches. In particular, exosomes are useful sources for biomarkers due to selective cargo loading and similarity to their parental cells. In this review, we summarize the recent findings to use exosomes as cancer biomarkers for early detection, diagnosis, and therapy selection.

Extracellular Vesicles as a Novel Liquid Biopsy-Based Diagnosis for the Central Nervous System, Head and Neck, Lung, and Gastrointestinal Cancers: Current and Future Perspectives

Simple Summary

To improve clinical outcomes, early diagnosis is mandatory in cancer patients. Several diagnostic approaches have been proposed, however, the main drawback relies on the invasive procedures required. Extracellular vesicles (EVs) are bilayer lipid membrane structures released by almost all cells and transferred to remote sites via the bloodstream. The observation that their cargo reflects the cell of origin has opened a new frontier for non-invasive biomarker discovery in oncology. Moreover, since EVs can be recovered from different body fluids, their impact as a Correctdiagnostic tool has gained particular interest. Hence, in the last decade, several studies using different biological fluids have been performed, showing the valuable contributions of EVs as tumour biomarkers, and their improved diagnostic power when combined with currently available tumour markers. In this review, the most relevant data on the diagnostic relevance of EVs, alone or in combination with the well-established tumour markers, are discussed.

Abstract

Early diagnosis, along with innovative treatment options, are crucial to increase the overall survival of cancer patients. In the last decade, extracellular vesicles (EVs) have gained great interest in biomarker discovery. EVs are bilayer lipid membrane limited structures, released by almost all cell types, including cancer cells. The EV cargo, which consists of RNAs, proteins, DNA, and lipids, directly mirrors the cells of origin. EVs can be recovered from several body fluids, including blood, cerebral spinal fluid (CSF), saliva, and Broncho-Alveolar Lavage Fluid (BALF), by non-invasive or minimally invasive approaches, and are therefore proposed as feasible cancer diagnostic tools. In this review, methodologies for EV isolation and characterization and their impact as diagnostics for the central nervous system, head and neck, lung, and gastrointestinal cancers are outlined. For each of these tumours, recent data on the potential clinical applications of the EV’s unique cargo, alone or in combination with currently available tumour biomarkers, have been deeply discussed.

Non-coding RNAs in exosomes and adipocytes cause fat loss during cancer cachexia

Cancer Cachexia (CC) is a disease that changes various metabolisms in human body. Fat metabolism is significantly affected in CC, leading to fat loss. Non-coding RNAs (ncRNAs) in adipocytes and exosomes secreted by tumor play an important role in fat loss. However, there is no related reviews summarizing how ncRNAs contribute to fat loss during CC. This review screens recent articles to summarize how ncRNAs are packaged, transported in exosomes, and play the role in fat loss. Not only does this review summarize the mechanisms, we also point out the research orientations in the future.

The role of exosomes in liquid biopsy for cancer diagnosis and prognosis prediction

Liquid biopsy is a revolutionary strategy in cancer diagnosis and prognosis prediction, which is used to analyze cancer cells or cancer-derived products through biofluids such as blood, urine and so on. Exosomes play a crucial role in mediating cell communication. A growing number of studies have reported that exosomes are involved in tumorigenesis, tumor growth, metastasis and drug resistance by delivering cargos including nucleic acids and protein. Thus, exosomes, as a new type of liquid biopsy, have the potential to be diagnostic or prognostic biomarkers. Herein, we elaborate on the current methods and introduce novel techniques for exosome isolation and characterization. Moreover, we elucidate the advantages of exosomes compared to other biological components in liquid biopsy and summarize the different exosomal biomarkers in cancer diagnosis and prognosis prediction.

Clinical Implications of Exosomes: Targeted Drug Delivery for Cancer Treatment

Exosomes are nanoscale vesicles generated by cells for intercellular communication. Due to their composition, significant research has been conducted to transform these particles into specific delivery systems for various disease states. In this review, we discuss the common isolation and loading methods of exosomes, some of the major roles of exosomes in the tumor microenvironment, as well as discuss recent applications of exosomes as drug delivery vessels and the resulting clinical implications.

Circulating exosomal long non-coding RNA H19 as a potential novel diagnostic and prognostic biomarker for gastric cancer

Objective

Long non-coding RNAs (lncRNAs) are involved in carcinogenesis and could be used as diagnostic biomarkers. Our study aimed to elucidate the clinical role of serum exosomal lncRNA H19 in gastric cancer (GC).

Methods

In this prospective clinical study, we determined serum exosomal lncRNA H19 levels in 81 patients with GC and analysed the correlations between serum lncRNA H19 levels and clinical characteristics. Receiver operating characteristics (ROC) curves were constructed to determine the diagnostic performance of exosomal lncRNA H19 in GC.

Results

Serum exosomal lncRNA H19 levels were significantly upregulated in patients with GC both before and after surgery compared with healthy controls. Furthermore, serum exosomal lncRNA H19 levels were significantly decreased after compared with before surgery in patients with GC. Preoperative lncRNA H19 levels were significantly correlated with TNM stage. The area under the ROC curve (AUC) value for exosomal lncRNA H19 was 0.849, which was significantly higher than the AUC values for cancer antigens 19-9 and 72-4 and carcinoembryonic antigen, either alone or combined.

Conclusions

These results suggest that circulating exosomal lncRNA H19 may be a potential biomarker with diagnostic and prognostic value in GC.

Extracellular vesicles as a promising biomarker resource in liquid biopsy for cancer

Liquid biopsy is a minimally invasive biopsy method that uses molecules in body fluids as biomarkers, and it has attracted attention as a new cancer therapy tool. Liquid biopsy has considerable clinical application potential, such as in early diagnosis, pathological condition monitoring, and tailored treatment development based on cancer biology and the predicted treatment response of individual patients. Extracellular vesicles (EVs) are lipid membranous vesicles released from almost all cell types, and they represent a novel liquid biopsy resource. EVs carry complex molecular cargoes, such as proteins, RNAs [e.g., mRNA and noncoding RNAs (microRNA, transfer RNA, circular RNA and long noncoding RNA)], and DNA fragments; these cargoes are delivered to recipient cells and serve as a cell-to-cell communication system. The molecular contents of EVs largely reflect the cell of origin and thus show cell-type specificity. In particular, cancer-derived EVs contain cancer-specific molecules expressed in parental cancer cells. Therefore, analysis of cancer-derived EVs might indicate the presence and nature of cancer. High-speed analytical technologies, such as mass spectrometry and high-throughput sequencing, have generated large data sets for EV cargoes that can be used to identify many candidate EV-associated biomarkers. Here, we will discuss the challenges and prospects of EV-based liquid biopsy compared to other biological resources (e.g., circulating tumor cells and cell-free DNA) and summarize the novel studies that have identified the remarkable potential of EVs as a cancer biomarker.

The role and application of small extracellular vesicles in gastric cancer

Gastric cancer (GC) is a common tumour that affects humans worldwide, is highly malignant and has a poor prognosis. Small extracellular vesicles (sEVs), especially exosomes, are nanoscale vesicles released by various cells that deliver bioactive molecules to recipient cells, affecting their biological characteristics, changing the tumour microenvironment and producing long-distance effects. In recent years, many studies have clarified the mechanisms by which sEVs function with regard to the initiation, progression, angiogenesis, metastasis and chemoresistance of GC. These molecules can function as mediators of cell-cell communication in the tumour microenvironment and might affect the efficacy of immunotherapy. Due to their unique physiochemical characteristics, sEVs show potential as effective antitumour vaccines as well as drug carriers. In this review, we summarize the roles of sEVs in GC and highlight the clinical application prospects in the future.

LncRNAs link cancer stemness to therapy resistance

Cancer stem cells (CSCs) are a cellular subpopulation accelerating cancer cell growth, invasion and metastasis and survival. After chemoradiotherapy, CSCs are enriched because of their survival advantages and lead to tumor relapse and metastasis. Elimination of CSCs is critically important for the radical treatment of human cancers. Long non-coding RNAs (lncRNAs) are a group of RNAs longer than 200 nucleotides and have no protein-coding potential. Aberrant expressions of lncRNAs are associated with human diseases including cancer. LncRNAs function as cancer biomarkers, prognostic factors and therapeutic targets. They induce cancer stemness by chromatin modification, transcriptional regulation or post-transcriptional regulation of target genes as a sponge or through assembling a scaffold complex. Several factors caused aberrant expressions of lncRNAs in CSCs such as genes mutations, epigenetic alteration and environmental stimuli. Targeting of lncRNAs has been demonstrated to significantly reverse the chemoradioresistance of CSCs. In this review, we have summarized the progress of studies regarding lncRNAs-mediated therapy resistance of CSCs and clarified the molecular mechanisms. Furthermore, we have for the first time analyzed the influences of lncRNAs on cell metabolism and emphasized the effect of tumor microenvironment on lncRNAs functions in CSCs. Overall, the thorough understanding of the association of lncRNAs and CSCs would contribute to the reversal of therapy resistance.

Clinical value of lncRNA CCAT1 in serum extracellular vesicles as a potential biomarker for gastric cancer

Long non-coding RNAs (lncRNAs) in extracellular vesicles (EVs) are considered to be novel non-invasive biomarkers for gastric cancer (GC). lncRNA colon cancer-associated transcript 1 (CCAT1) is aberrantly expressed in certain types of cancer. However, the role of EV lncRNA CCAT1 in patients with GC remains unclear. The current study aimed to assess the expression levels of lncRNA CCAT1 in the serum EVs of patients with GC and evaluate its potential clinical value. EVs were isolated from serum using a commercial kit and ultracentrifugation, and were identified by transmission electron microscopy, nanoparticle tracking analysis and western blotting. Serum EV lncRNA CCAT1 levels in patients with GC, chronic gastritis or atypical hyperplasia and healthy control subjects were detected by reverse transcription-quantitative PCR. Additionally, lncRNA CCAT1 was detected in GC and adjacent non-cancerous tissue samples. Serum EVs were successfully isolated and identified in all patients. The results revealed that serum EV lncRNA CCAT1 levels in patients with GC were significantly higher compared with those in healthy controls, patients with chronic gastritis or atypical hyperplasia (all P<0.05). Additionally, EV lncRNA CCAT1 expression levels were significantly different among various groups based on the depth of invasion, distant metastasis and the Tumor-Node-Metastasis stage. The area under the curve (AUC) value of EV lncRNA CCAT1 was 0.890 [95% confidence interval (CI), 0.826–0.937] with 79.6% sensitivity and 92.6% specificity. The combination of EV lncRNA CCAT1 and carcinoembryonic antibody produced an AUC value of 0.910 (95% CI, 0.849–0.951) with the sensitivity and specificity of 80.5 and 92.6%, respectively. In addition, lncRNA CCAT1 was determined to be stable in serum EVs. The expression levels of lncRNA CCAT1 in GC tissue were positively correlated with those in serum EVs, and high levels of lncRNA CCAT1 were associated with a low disease-free survival rate in patients with GC. The results of the present study demonstrated that serum EV lncRNA CCAT1 levels were upregulated in patients with GC compared with those healthy subjects and patients with other illnesses, and may therefore be used as a novel biomarker for this type of cancer.

Isolation and characterization of extracellular vesicles for clinical applications in cancer - time for standardization?

Extracellular vesicles (EVs) are nanometer sized lipid enclosed particles released by all cell types into the extracellular space and biological fluids in vivo, and into cell culture media in vitro. An important physiological role of EVs is cell-cell communication. EVs interact with, and deliver, their contents to recipient cells in a functional capacity; this makes EVs desirable vehicles for the delivery of therapeutic cargoes. In addition, as EVs contain proteins, lipids, glycans, and nucleic acids that reflect their cell of origin, their potential utility in disease diagnosis and prognostication is of great interest. The number of published studies analyzing EVs and their contents in the pre-clinical and clinical setting is rapidly expanding. However, there is little standardization as to what techniques should be used to isolate, purify and characterize EVs. Here we provide a comprehensive literature review encompassing the use of EVs as diagnostic and prognostic biomarkers in cancer. We also detail their use as therapeutic delivery vehicles to treat cancer in pre-clinical and clinical settings and assess the EV isolation and characterization strategies currently being employed. Our report details diverse isolation strategies which are often dependent upon multiple factors such as biofluid type, sample volume, and desired purity of EVs. As isolation strategies vary greatly between studies, thorough EV characterization would be of great importance. However, to date, EV characterization in pre-clinical and clinical studies is not consistently or routinely adhered to. Standardization of EV characterization so that all studies image EVs, quantitate protein concentration, identify the presence of EV protein markers and contaminants, and measure EV particle size and concentration is suggested. Additionally, the use of RNase, DNase and protease EV membrane protection control experiments is recommended to ensure that the cargo being investigated is truly EV associated. Overall, diverse methodology for EV isolation is advantageous as it can support different sample types and volumes. Nevertheless, EV characterization is crucial and should be performed in a rigorous manor.

Circulating long noncoding RNAs as potential biomarkers for stomach cancer: a systematic review and meta-analysis

Background

Recent researches have suggested that long noncoding RNA (lncRNA) is involved in the tumorigenesis and development of stomach cancer (SC). This meta-analysis aimed to identify the diagnostic performance of circulating lncRNAs in SC.

Methods

All relevant studies were systematically searched through PubMed, Web of Science, Cochrane Library, and EMBASE databases. The diagnostic values of lncRNAs were mainly assessed by pooled sensitivity, specificity, and summary receiver operating characteristic area under the curve (SROC AUC). Meta-DiSc 1.4, Review Manager 5.3, and STATA 12.0 were used for statistical analysis. The protocol for this systematic review was registered on INPLASY (INPLASY202120079) and is available in full on the inplasy.com (10.37766/inplasy2021.2.0079).

Results

A total of 42 eligible studies were included in this meta-analysis. The pooled sensitivity, specificity, and SROC AUC were 0.78 (95%CI 0.75–0.81), 0.75 (95%CI 0.71–0.78), and 0.83 (95%CI 0.80–0.86), respectively, suggesting that the lncRNAs test had a high accuracy for the diagnosis of SC. Obvious heterogeneity might come from the type of lncRNA through subgroup and meta-regression analysis. Fagan diagram shows the clinical value of lncRNAs test in SC.

Conclusions

Abnormal expression of circulating lncRNAs exhibits a high efficacy for diagnosing SC, which is promising in clinical application.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-021-02194-6.

Circulating Serum Exosomal Long Non-Coding RNAs FOXD2-AS1, NRIR, and XLOC_009459 as Diagnostic Biomarkers for Colorectal Cancer

Background

Exosomes derived from cancer cells encapsulate various kinds of tumor-specific molecules and thus can interact with adjacent or distant cells to mediate information exchange. Long non-coding RNAs (lncRNAs) in exosomes have the potential as diagnostic and prognostic biomarkers in different types of cancers. The current study was aimed to identify circulating exosomal lncRNAs for the diagnosis of colorectal cancer (CRC).

Methods

Exosomes were isolated from the serum by ultracentrifugation and verified by transmission electron microscope (TEM), qNano, and immunoblotting. Exosomal lncRNAs FOXD2-AS1, NRIR, and XLOC_009459 were selected by lncRNA microarray and validated by qPCR in 203 CRC patients and 201 healthy donors. The receiver operating characteristic curve (ROC) was used to assess the diagnostic efficiency of serum exosomal lncRNAs.

Results

Exosomal FOXD2-AS1, NRIR, and XLOC_009459 (TCONS_00020073) levels were significantly upregulated in 203 CRC patients and 80 early-stage CRC patients compared to 201 healthy donors, possessing the area under the curve (AUC) of 0.728, 0.660, and 0.682 for CRC, as well as 0.743, 0.660, and 0.689 for early-stage CRC, respectively. Notably, their combination demonstrated the markedly elevated AUC of 0.736 for CRC and 0.758 for early-stage CRC, indicating their potential as diagnostic biomarkers for CRC.

Conclusions

Our data suggested that exosomal lncRNAs FOXD2-AS1, NRIR, and XLOC_009459 act as the promising biomarkers for the diagnostics of CRC and early-stage CRC.

Exosomes: A new frontier under the spotlight for diagnosis and treatment of gastrointestinal diseases

Exosomes are small plasma membrane-bound multivesicular bodies ranging in size from 20-100 nm. Exosomes are degraded fragments of mRNA, microRNA, and enriched in proteins, lipids, and nucleic acid. They are produced in the endosomes of most eukaryotic cells and once secreted, exosomes are involved in cell to cell communication and remodeling of the matrix in the extracellular compartment. Exosome biogenesis plays a crucial role in cellular development, inflammation, immunity, hemostasis, carcinogenesis, and degeneration. Due to their unique biochemical and biophysical properties, exosomes serve a variety of functions including biomarkers of diagnostic and prognostic significance. Besides, there is an increasing level of evidence to expand our understanding of the exosomes as novel therapeutic agents. Inflammatory bowel disease (IBD) such as Crohn's disease and ulcerative colitis, hepatic fibrosis, and gastrointestinal malignancies such as colorectal cancer are the potential avenues where exosomes can be applied as cell therapy and immunotherapy and have shown promising results in several in-vitro and animal models. The purpose of this review article is to highlight the emerging role of exosomes as the diagnostic and therapeutic tool in various diseases involving the gastrointestinal tract like IBD, hepatocellular carcinoma, and colon cancer. A thorough literature search was performed on databases such as PubMed, Ovid Medline, and EMBASE to achieve the objectives of this review article.

Early detection of gastric cancer beyond endoscopy - new methods

Early detection of gastric cancer is remaining a challenge. This review summarizes current knowledge on non-invasive methods that could be used for the purpose. The role of traditional cancer markers such as CEA, CA 72-4, CA 19-9, CA 15-3, and CA 12-5 lies mainly in therapy monitoring than early detection. Most extensive studied biomarkers (pepsinogens, ABC method) are aiming at the detection of precancerous lesions with modest sensitivity for cancer. Tests based on the detection of cancer-specific methylation patterns (PanSeer), circulating proteins and mutations in circulating tumour DNA (CancerSEEK), as well as miRNA panels have demonstrated promising results bringing those closer to practice. More extensive research is required before tests based on the detection of circulating tumour cells, extracellular vesicles and cell-free RNA could reach the practice. Detection of volatile organic compounds in the human breath is a promising development; sensor technologies for this purpose could be very attractive in screening settings.

Exosome as potential biomarkers for gastrointestinal tumors

INTRODUCTION

Exosomes are polyvesicles that are formed by invagination of intracellular lysosomal particles, and are released into the extracellular matrix after the fusion of polyvesicular outer membrane and cell membrane. In the body, immune response, antigen presentation, cell migration, cell differentiation and tumor invasion are closely related to tumorigenesis and tumor progression. This study aimed to conduct a meta-analysis for evaluating the clinicopathological, diagnostic and prognostic significance of exosomal expression in gastrointestinal tumors.

METHODS

The original English articles were systematically searched in the online databases. The diagnostic accuracy, prognostic utility and clinicopathological correlation of gastrointestinal tumors were investigated. The quality assessment for studies of diagnostic accuracy II and Newcastle-Ottawa scale were used for quality evaluation, and the data was strictly extracted to judge the deviation of the study.

RESULTS

A total of 14 studies with 1837 gastrointestinal tumor patients were included. The change in exosomal expression showed significant correlation with poor clinicopathological parameters (tumor diameter: combined P = .00024394; differentiation: combined P = 2.796e-08; lymphatic metastasis: P = 9.610e-07; distant metastasis: combined P = .00017326; pathological classification: combined P = .00875213; invasion depth: combined P = 3.504e-08) carcinoembryonic antigen (combined P = . 04458857) and tumor location (combined P = .00145983). The difference in the area under the curve between gastrointestinal tumor patients and healthy people showed an area under the curve of 0.89 (95%Cl 0.85-0.91) and heterogeneity of 0.59, 95% CI=[0.55-0.68]. The sensitivity was 0.88 (95%Cl 0.83 mi 0.91), the specificity was 0.72 (95%Cl 0.63 mi 0.80), and the diagnostic odds ratio was 18 (10-33). The results of survival analysis revealed that the abnormally expressed exosomes were significantly correlated with poor overall survival (hazard ratio =2.81, 95% CI: 2.02-3.93, P=0.013∗ 62.7%∗).

CONCLUSION

The abnormally expressed exosomes might act as auxiliary biomarkers in diagnosing gastrointestinal tumors and demonstrated good prognostic significance in predicting the survival of patients with gastrointestinal tumors.

Molecular targeted treatment and drug delivery system for gastric cancer

Gastric cancer is still a major cancer worldwide. The early diagnosis rate of gastric cancer in most high incidence countries is low. At present, the overall treatment effect of gastric cancer is poor, and the median overall survival remains low. Most of the patients with gastric cancer are in an advanced stage when diagnosed, and drug treatment has become the main means. Thus, new targeted drugs and therapeutic strategies are the hope of improving the therapeutic effect of gastric cancer. In this review, we summarize the new methods and advances of targeted therapy for gastric cancer, including novel molecular targeted therapeutic agents and drug delivery systems, with a major focus on the development of drug delivery systems (drug carriers and targeting peptides). Elaborating these new methods and advances will contribute to the management of gastric cancer.

Identifying Novel Biomarkers Ready for Evaluation in Low-Prevalence Populations for the Early Detection of Upper Gastrointestinal Cancers: A Systematic Review

Introduction

Detecting upper gastrointestinal (GI) cancers in primary care is challenging, as cancer symptoms are common, often non-specific, and most patients presenting with these symptoms will not have cancer. Substantial investment has been made to develop biomarkers for cancer detection, but few have reached routine clinical practice. We aimed to identify novel biomarkers for upper GI cancers which have been sufficiently validated to be ready for evaluation in low-prevalence populations.

Methods

We systematically searched MEDLINE, Embase, Emcare, and Web of Science for studies published in English from January 2000 to October 2019 (PROSPERO registration CRD42020165005). Reference lists of included studies were assessed. Studies had to report on second measures of diagnostic performance (beyond discovery phase) for biomarkers (single or in panels) used to detect pancreatic, oesophageal, gastric, and biliary tract cancers. We included all designs and excluded studies with less than 50 cases/controls. Data were extracted on types of biomarkers, populations and outcomes. Heterogeneity prevented pooling of outcomes.

Results

We identified 149 eligible studies, involving 22,264 cancer cases and 49,474 controls. A total of 431 biomarkers were identified (183 microRNAs and other RNAs, 79 autoantibodies and other immunological markers, 119 other proteins, 36 metabolic markers, 6 circulating tumour DNA and 8 other). Over half (n = 231) were reported in pancreatic cancer studies. Only 35 biomarkers had been investigated in at least two studies, with reported outcomes for that individual marker for the same tumour type. Apolipoproteins (apoAII-AT and apoAII-ATQ), and pepsinogens (PGI and PGII) were the most promising biomarkers for pancreatic and gastric cancer, respectively.

Conclusion

Most novel biomarkers for the early detection of upper GI cancers are still at an early stage of matureness. Further evidence is needed on biomarker performance in low-prevalence populations, in addition to implementation and health economic studies, before extensive adoption into clinical practice can be recommended.

Electronic Supplementary Material

The online version of this article (10.1007/s12325-020-01571-z) contains supplementary material, which is available to authorized users.

Roles of Bile-Derived Exosomes in Hepatobiliary Disease

Exosomes are vesicles with a diameter of 30-150 nm produced by living cells and secreted into the extracellular matrix. Exosomes mediate cellular communication by carrying active molecules, such as nucleic acids, proteins, and liposomes. Although exosomes are found in various body fluids, little is known about bile-derived exosomes. This review is the first to summarize the methods of bile storage and isolation of biliary exosomes, highlighting the roles of bile-derived exosomes, especially exosomal noncoding RNAs, in physiological and disease states and discussing their potential clinical applications.

The Significance of Exosomal RNAs in the Development, Diagnosis, and Treatment of Gastric Cancer

Gastric cancer (GC) is one of the most common malignancies in the world. Exosomes, a subset of extracellular vesicles with an average diameter of 100 nm, contain and transfer a variety of functional macromolecules such as proteins, lipids, and nucleic acids. A large number of studies indicated that exosomes can play a significant role in the initiation and development of GC via facilitating intercellular communication between gastric cancer cells and microenvironment. Exosomal RNAs, one of the key functional cargos, are involved in the pathogenesis, development, and metastasis of GC. In addition, recent studies elucidated that exosomal RNAs may serve as diagnostic and prognostic biomarkers or therapeutic targets for GC. In this review, we summarized the function of exosomal RNA in the tumorigenesis, progression, diagnosis, and treatment of GC, which may further unveil the functions of exosome and promote the potentially diagnostic and therapeutic application of exosomes in GC.

Lab in a tube: Isolation, extraction, and isothermal amplification detection of exosomal long noncoding RNA of gastric cancer

Tumor-derived exosomes that inherit molecular information on parental cells hold great promise for cancer diagnostics. Currently, two main technical challenges, time-consuming and labor-intensive isolation of exosome and nucleic acid extraction with limited recovery that have restricted the detection of ultralow abundance exosomal nucleic acids. Here, we proposed a simple, efficient and "lab in a tube" system for the detection of exosomal nucleic acids, which fully integrated exosomes enrichment using immunomagnetic beads (IMB) (10 min), fast exosomes lysis based on NP-40 lysate (5 min) and sensitive loop-mediated isothermal amplification (LAMP) in a tube. This method was demonstrated by detecting two exosomal long noncoding RNA biomarkers of gastric cancer (HOTTIP and lncRNA-GC1) with a dynamic detection ranging from 300 ng/μL to 10 ng/μL, and the detection limit of LAMP was 10 ng/μL. Additionally, this platform exhibited good performance in the analysis of exosomal HOTTIP RNA directly in human serum samples, which has the potential for detection of low-abundance exosomal nucleic acid biomarkers from cancers.

Long non-coding RNA MSC-AS1 facilitates the proliferation and glycolysis of gastric cancer cells by regulating PFKFB3 expression

Long non-coding RNA musculin antisense RNA 1 (lncRNA MSC-AS1) has been recognized as an oncogene in pancreatic cancer, hepatocellular carcinoma, nasopharyngeal carcinoma, and renal cell carcinoma. However, the functional significance of MSC-AS1 and its underlying mechanism in gastric cancer (GC) progression remain unclear. In this study, we demonstrated that the expression of MSC-AS1 in GC tissues was significantly higher than that in non-tumor tissues. Moreover, the elevated level of MSC-AS1 was detected in GC cells (MKN-45, AGS, SGC-7901, and MGC-803) compared to normal GES-1 gastric mucosal cells. The cancer genome atlas (TCGA) data further indicated that the high level of MSC-AS1 was closely correlated with advanced tumor stage and poor prognosis of GC. Next, we revealed that MSC-AS1 knockdown inhibited the proliferation, glucose consumption, lactate production, and pyruvate production of MGC-803 cells. Conversely, MSC-AS1 overexpression enhanced the proliferation and glycolysis of AGC cells. Mechanistically, modulating MSC-AS1 level affected the expression of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), but did not impact the levels of hexokinase 2 (HK2) and pyruvate kinase M2 (PKM2) in GC cells. Based on this, we reversed the MSC-AS1 knockdown-induced the inhibition of cell proliferation and glycolysis by restoring PFKFB3 expression in MGC-803 cells. In conclusion, MSC-AS1 facilitated the proliferation and glycolysis of GC cells by maintaining PFKFB3 expression.

Exosomal long non-coding RNAs in the diagnosis and oncogenesis of pancreatic cancer

Extracellular vesicles, specifically exosomes, play a significant role as an extracellular messenger through their transporting cargo. Of particular interest are the potential roles they play in pancreatic cancer, one of the leading causes of cancer-related mortality worldwide. Pancreatic Ductal Adenocarcinoma displays high chemo-resistance and metastatic ability, which may be influenced by cancer-derived exosomes carrying proteins, lipids and RNA. To date, among the most extensively examined exosomal molecular cargo there are long non-coding RNAs (lncRNAs) that, despite the increasing interest in their role and functions, are relatively poorly understood compared to other RNA transcripts. Nevertheless, we have witnessed an increasing interest for lncRNAs roles and functions in the past decade. For example, lncRNAs have been investigated as potential biomarkers for diagnosing pancreatic cancer and may have a role as therapeutics targets for precision medicine, but may also directly intervene in tumour progression features such as metastasis, epithelial to mesenchymal transition and resistance of cancer cells towards chemotherapy agents. The function of lncRNAs within various cancer exosomes is still undefined. In this review, we summarize the current knowledge on pancreatic cancer-derived exosome specific lncRNAs having prominent roles in genome integrity, pancreatic cancer progression and in other oncogenic hallmarks.

Isolation and characterization of exosomes for cancer research

Exosomes are a subset of extracellular vesicles that carry specific combinations of proteins, nucleic acids, metabolites, and lipids. Mounting evidence suggests that exosomes participate in intercellular communication and act as important molecular vehicles in the regulation of numerous physiological and pathological processes, including cancer development. Exosomes are released by various cell types under both normal and pathological conditions, and they can be found in multiple bodily fluids. Moreover, exosomes carrying a wide variety of important macromolecules provide a window into altered cellular or tissue states. Their presence in biological fluids renders them an attractive, minimally invasive approach for liquid biopsies with potential biomarkers for cancer diagnosis, prediction, and surveillance. Due to their biocompatibility and low immunogenicity and cytotoxicity, exosomes have potential clinical applications in the development of innovative therapeutic approaches. Here, we summarize recent advances in various technologies for exosome isolation for cancer research. We outline the functions of exosomes in regulating tumor metastasis, drug resistance, and immune modulation in the context of cancer development. Finally, we discuss prospects and challenges for the clinical development of exosome-based liquid biopsies and therapeutics.

Assessment of circulating HISLA as a potential biomarker for breast cancer diagnosis and prognosis

Breast cancer (BC) is the most frequently encountered and aggressive type of malignant tumor and affects the health of females across the globe. Approximately 30% of patients that are newly diagnosed have a high risk of subsequent metastasis and relapse. HIF-1α-stabilizing long noncoding RNA (HISLA) packaged in exosome has been recently identified and revealed as an important oncogenic gene in promoting BC progress. Thus, we sought to investigate whether serum circulating HISLA was involved in dynamics underlying its applicability for the diagnosis and prognosis of BC. We assessed serum HISLA expression in 40 patients with BC and 20 healthy controls to investigate its roles in BC using quantitative real-time polymerase chain reaction (qRT-PCR). We also assessed measures of correlation of clinical and pathological parameters with prognoses of BC patients. Our findings suggested that serum HISLA expression in BC patients was significantly higher than in healthy controls. Furthermore, high expression of serum HISLA was positively associated with advanced stage lymph node metastasis. Expression of HISLA was reduced in postoperative BC patients' serum samples, compared with preoperative serum samples. Pearson correlation assessments indicated significant correlation between serum HISLA expression and the tissue sample HISLA expression in BC patients. Our findings suggested that serum HISLA may serve as newfound biomarker which could help to improve diagnoses and prognoses for BC-afflicted patients.

EVs as Potential New Therapeutic Tool/Target in Gastrointestinal Cancer and HCC

For more than a decade, extracellular vesicles (EVs) have been in focus of science. Once thought to be an efficient way to eliminate undesirable cell content, EVs are now well-accepted as being an important alternative to cytokines and chemokines in cell-to-cell communication route. With their cargos, mainly consisting of functional proteins, lipids and nucleic acids, they can activate signalling cascades and thus change the phenotype of recipient cells at local and systemic levels. Their substantial role as modulators of various physiological and pathological processes is acknowledged. Importantly, more and more evidence arises that EVs play a pivotal role in many stages of carcinogenesis. Via EV-mediated communication, tumour cells can manipulate cells from host immune system or from the tumour microenvironment, and, ultimately, they promote tumour progression and modulate host immunity towards tumour's favour. Additionally, the role of EVs in modulating resistance to pharmacological and radiological therapy of many cancer types has become evident lately. Our understanding of EV biology and their role in cancer promotion and drug resistance has evolved considerably in recent years. In this review, we specifically discuss the current knowledge on the association between EVs and gastrointestinal (GI) and liver cancers, including their potential for diagnosis and treatment.

Small extracellular vesicles (sEVs): discovery, functions, applications, detection methods and various engineered forms

INTRODUCTION

Extracellular vesicles (EVs) are cell-created delivery systems of proteins, lipids, or nucleic acids, and means of extracellular communication. Though sEVs were initially considered to be the waste disposal mechanism, today they are at the forefront of research with different biological and pathological functions. Such EVs play a key role in the immunoregulation, CNS development, nervous system physiology, mammary gland development, induction of immunosuppression in pregnancy, the developmental signaling pathways, regeneration of different tissues, inflammation, angiogenesis, coagulation, apoptosis, stem cell differentiation, and extracellular matrix turnover.

AREAS COVERED

SEVs contribute to the pathogenesis of different cancers and the progression of various neurodegenerative diseases, infections, as well as metabolic and cardiovascular diseases. Expert Opinion: There is no exact classification for EVs; however, according to size, density, morphological features, content, and biogenesis, they can be categorized into three major classes: microvesicles (ectosomes or microparticles), apoptotic bodies, and sEVs. SEVs, as an important class of EVs, have a crucial role in distinct biological functions. Moreover, shedding light on different structural and molecular aspects of sEV has led to their application in various therapeutic, diagnostic, and drug delivery fields. In this review, we have endeavored to elaborate on different aspects of EVs, especially sEVs.

Exosomal non‑coding RNAs: Novel biomarkers with emerging clinical applications in gastric cancer (Review)

Gastric cancer (GC) is one of the most common types of malignant tumor and it demonstrates high mortality rates. The majority of cases of GC are diagnosed at an advanced stage, which seriously endangers the health of the patient. Therefore, discovering a novel diagnostic method for GC is a current priority. Exosomes are 40 to 150-nm-diameter vesicles consisting of a lipid bilayer secreted by a variety of cells that exist in multiple different types of body fluids. Exosomes contain diverse types of active substances, including RNAs, proteins and lipids, and play important roles in tumor cell communication, metastasis and neovascularization, as well as tumor growth. Non-coding RNAs (ncRNAs) do not code proteins, and instead have roles in a variety of genetic mechanisms, such as regulating the structure, expression and stability of RNAs, and modulating the translation and function of proteins. In recent years, exosomal ncRNAs have become a novel focus in research. An increasing number of studies have demonstrated that exosomal ncRNAs can be used in the prediction and treatment of GC. The present review briefly discusses the role of exosomal ncRNAs as a potential biomarker, and summarizes important regulatory genes involved in the development and progression of GC.

Extracellular Vesicles: New Endogenous Shuttles for miRNAs in Cancer Diagnosis and Therapy?

Extracellular Vesicles (EVs) represent a heterogeneous population of membranous cell-derived structures, including cargo-oriented exosomes and microvesicles. EVs are functionally associated with intercellular communication and play an essential role in multiple physiopathological conditions. Shedding of EVs is frequently increased in malignancies and their content, including proteins and nucleic acids, altered during carcinogenesis and cancer progression. EVs-mediated intercellular communication between tumor cells and between tumor and stromal cells can modulate, through cargo miRNA, the survival, progression, and drug resistance in cancer conditions. These consolidated suggestions and EVs’ stability in bodily fluids have led to extensive investigations on the potential employment of circulating EVs-derived miRNAs as tumor biomarkers and potential therapeutic vehicles. In this review, we highlight the current knowledge about circulating EVs-miRNAs in human cancer and the application limits of these tools, discussing their clinical utility and challenges in functions such as in biomarkers and instruments for diagnosis, prognosis, and therapy.

Long Non-Coding RNA BLACAT1 in Human Cancers

Long non-coding RNAs (lncRNAs) are a cluster of RNAs with more than 200 nucleotides in length, which lack protein-coding capacity. They are important regulators of numerous cellular processes, including gene transcription, translation, and posttranslational modification, especially in tumor initiation and progression. Aberrant expression of lncRNA bladder cancer-associated transcript 1 (BLACAT1) has been reported in various human cancers and was usually associated with unfavorable prognosis. Previous studies have revealed that dysregulation of BLACAT1 could promote the proliferation and metastasis of cancer cells. In this review, we summarize the present understanding of the functions and underlying mechanisms of BLACAT1 in the occurrence and development of various human cancers and discuss the roles of this lncRNA in cancers, including its promising application as a prognostic biomarker or a novel therapeutic target for malignancies.

Serum LncRNA-ATB and FAM83H-AS1 as diagnostic/prognostic non-invasive biomarkers for breast cancer

AIMS

Circulating long non-coding RNAs (lncRNAs) have proven to be useful non-invasive tools for diagnosis of various cancers. FAM83H antisense RNA 1 (FAM83H-AS1) and lncRNA activated by TGF β (lncRNA-ATB) are two lncRNAs that have been shown to play an important role in different cancer types including breast cancer. The primary aim of our study was to investigate the potential role of serum FAM83H-AS1 and lncRNA-ATB as diagnostic/prognostic markers for breast cancer patients.

MAIN METHODS

Serum expression levels of FAM83H-AS1 and lncRNA-ATB were analyzed in 90 breast cancer patients and 30 age- and sex-matched healthy controls using RT-qPCR.

KEY FINDINGS

We found that FAM83H-AS1 and lncRNA-ATB were significantly overexpressed in sera of breast cancer patients compared to controls (p = 0.000 for both). Analysis of receiver operating characteristic curve demonstrated that lncRNA-ATB had a higher area under curve (AUC) value than the conventional tumor marker cancer antigen 15-3 (CA15-3) (AUC: 0.844, p = 0.000 versus 0.738, p = 0.002) for early diagnosis of breast cancer in patients with stage I-II. On the other hand, FAM83H-AS1 showed a significant correlation with tumor-node metastasis (TNM) stages, large tumor size and lymph node metastasis, suggesting a prognostic rather than diagnostic value.

SIGNIFICANCE

This is the first study to demonstrate that serum lncRNA-ATB could be used as a non-invasive diagnostic marker for early stages of breast cancer. Furthermore, serum FAM83H-AS1 has a potential ability for monitoring of progression and staging of breast cancer.

Diagnostic performance of circulating exosomes in human cancer: A meta-analysis

BACKGROUND

Cancer has become a public health problem with high morbidity and mortality. Recent publications have shown that exosomes can be used as potential diagnostic biomarkers of cancer. However, the diagnostic accuracy and reliability of circulating exosomes remain unclear. The present meta-analysis was conducted to comprehensively summarize the overall diagnostic performance of circulating exosomes for cancer.

METHODS

Eligible studies published up to June 27, 2019, on PubMed, Embase, and Cochrane Library were selected for the meta-analysis. All statistical analyses were performed by STATA 15.1 statistical software and Meta-DiSc 1.4. Quality Assessment for Studies of Diagnostic Accuracy 2 tool was used to access the quality of included studies. A bivariate mixed-effects model was applied to calculate the diagnostic indexes from included studies.

RESULTS

A total of 5924 participants comprising 3161 cases and 2763 controls from 42 eligible studies were analyzed. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio, and the area under the curve with 95% confidence intervals (95% CI) were as follows: 0.79 (0.75-0.82), 0.81 (0.78-0.84), 4.1 (3.5-4.8), 0.26 (0.22-0.31), 16 (12-21), and 0.87 (0.84-0.89), respectively. Sensitivity analysis suggested no study exclusively contributed to the heterogeneity, and Deeks' funnel plot asymmetry test indicated no potential publication bias (P = .09).

CONCLUSIONS

The meta-analysis indicated that circulating exosomes could serve as effective and minimally invasive biomarkers for diagnosis of cancer, especially in patients with hepatocellular carcinoma or ovarian cancer, serum-based samples and exosomal proteins.

Non-coding RNAs in gastric cancer

Non-coding RNAs (ncRNAs) are functional RNA molecules that play crucial regulatory roles in many fundamental biological processes. The dysregulation of ncRNAs is significantly associated with the progression of human cancers, including gastric cancer. In this review, we have summarized the oncogenic or tumor-suppressive roles and the regulatory mechanisms of lncRNAs, miRNAs, circRNAs and piRNAs, and have discussed their potential as biomarkers or therapeutic targets in gastric cancer.

Long non-coding RNAs in gastric cancer: New emerging biological functions and therapeutic implications

Gastric cancer (GC) is currently the fourth most common malignancy and the third leading cause of cancer-related deaths worldwide. Long non-coding RNAs (lncRNAs), transcriptional products with more than 200 nucleotides, are not as well-characterized as protein-coding RNAs. Accumulating evidence has recently revealed that maladjustments of diverse lncRNAs may play key roles in multiple genetic and epigenetic phenomena in GC, affecting all aspects of cellular homeostasis, such as proliferation, migration, and stemness. However, the full extent of their functionality remains to be clarified. Considering the lack of viable biomarkers and therapeutic targets, future research should be focused on unravelling the intricate relationships between lncRNAs and GC that can be translated from bench to clinic. Here, we summarized the state-of-the-art advances in lncRNAs and their biological functions in GC, and we further discuss their potential diagnostic and therapeutic roles. We aim to shed light on the interrelationships between lncRNAs and GC with respect to their potential therapeutic applications. With better understanding of these relationships, the biological functions of lncRNAs in GC development will be exploitable, and promising new strategies developed for the prevention and treatment of GC.

Commercial and emerging technologies for cancer diagnosis and prognosis based on circulating tumor exosomes

Exosomes are nano-sized extracellular vesicles excreted by mammalian cells that circulate freely in the bloodstream of living organisms. Exosomes have a lipid bilayer that encloses genetic material used in intracellular communication (e.g. double-stranded DNA, micro-RNAs, and messenger RNA). Recent evidence suggests that dysregulation of this genetic content within exosomes has a major role in tumor progression in the surrounding microenvironment. Motivated by this discovery, we focused here on using exosomal biomarkers as a diagnostic and prognostic tool for cancer. In this review, we discuss recently discovered exosome-derived proteomic and genetic biomarkers used in cancer diagnosis and prognosis. Although several genetic biomarkers have been validated for their diagnostic values, proteomic biomarkers are still being actively pursued. We discuss both commercial technologies and emerging technologies for exosome isolation and analysis. Emerging technologies can be classified into optical and non-optical methods. The working principle of each method is briefly discussed as well as advantages and limitations.

Long noncoding RNAs in gastric cancer: From molecular dissection to clinical application

Long noncoding RNAs (lncRNAs) are important regulators of cell processes that are usually dysregulated in gastric cancer (GC). Based on their high specificity and ease of detection in tissues and body fluids, increasing attention has spurred the study of the roles of lncRNAs in GC patients. Thus, it is necessary to elucidate the molecular mechanisms and further explore the clinical applications of lncRNAs in GC. In this review, we summarize current knowledge to examine dysregulated lncRNAs in GC and their underlying molecular mechanisms and activities in GC, which involve microRNA sponging, mRNA stability, genetic variants, alternative splicing, transcription factor binding, and epigenetic modification. More significantly, the potential of lncRNAs as prognostic, circulating, and drug-resistant biomarkers for GC is also described. This review highlights the method of dissecting molecular mechanisms to explore the clinical application of lncRNAs in GC. Overall, this review offers assistance in using lncRNAs as novel candidates for molecular mechanisms and for the identification of revolutionary biomarkers for GC.

Exosomes as Actively Targeted Nanocarriers for Cancer Therapy

In recent years, it has been found that exosomes can be used as nanocarriers, which can be used in the treatment of tumors by carrying contents. The exosomes are derived from the secretion of the organism's own cells and are characterized by a phospholipid bilayer structure and a small particle size. These characteristics guarantee that the exosomes can carry a wide range of tumor drugs, deliver the drug to the cancer, and reduce or eliminate the tumor drug band. The toxic side effects were significantly eliminated; meanwhile, the therapeutic effects of the drug on the tumor were remarkably improved. This paper reviewed the strategies and drugs presented by different scholars for the treatment of tumors based on the drugs carried by exosomes.

The potential of liquid biopsies in gastrointestinal cancer

BACKGROUND

Liquid biopsy is a novel approach for cancer diagnosis, the value of which in human gastrointestinal (GI) cancer has been confirmed by the previous studies. This article summarized the recent advances in liquid biopsy with a focus on novel technologies and the use of it in the screening, monitoring, and treatment of human GI cancer.

CONTENT

The concept of liquid biopsy was first used to define the detection of circulating tumor cells (CTCs) in cancer patients, and has been expanded to other biomarkers in blood and body fluids, such as circulating tumor DNA (ctDNA), extracellular vesicles (EVs) and circulating tumor RNA. If analyzed with proper and advanced techniques like next generation sequencing (NGS) or proteomics, liquid biopsies can open an enormous array of potential biomarkers. The amount changes of target biomarkers and the mutation of genetic materials provide quantitative and qualitative information, which can be utilized clinically for cancer diagnosis and disease monitoring.

SUMMARY

As a highly efficient, minimally invasive, and cost-effective approach to diagnose and evaluate prognosis of GI cancer, liquid biopsy has lots of advantages over traditional biopsy and is promising in future clinical utility. If the challenges are overcome in the near future, liquid biopsy will become a widely available and dependable option.

Advances in the role of exosomal non-coding RNA in the development, diagnosis, and treatment of gastric cancer (Review)

Exosomes are small vesicles secreted by a variety of cells that contain vrious biological macromolecules, including RNA, non-coding RNA and protein. An increasing number of studies have demonstrated that exosomes and particularly the non-coding RNAs they contain, serve important roles in many cellular processes, including the transmission of information. It is well established that the occurrence and development of gastric cancer, one of the four most common malignant tumors worldwide, involves the transmission of information. Based on the urgent need for the elucidation of the mechanism involved in this process, as well as advances in the diagnosis and treatment of gastric cancer, numerous reports have assessed the association between non-coding RNAs in exosomes and gastric cancer. The purpose of the present review was to summarize recent evidence on certain non-coding RNAs associated with the development, diagnosis and treatment of gastric cancer.

Tumor circulome in the liquid biopsies for digestive tract cancer diagnosis and prognosis

Digestive tract cancer is one of the main diseases that endanger human health. At present, the early diagnosis of digestive tract tumors mainly depends on serology, imaging, endoscopy, and so on. Although tissue specimens are the gold standard for cancer diagnosis, with the rapid development of precision medicine in cancer, the demand for dynamic monitoring of tumor molecular characteristics has increased. Liquid biopsy involves the collection of body fluids via non-invasive approaches, and analyzes biological markers such as circulating tumor cells, circulating tumor DNA, circulating cell-free DNA, microRNAs, and exosomes. In recent years, liquid biopsy has become more and more important in the diagnosis and prognosis of cancer in clinical practice due to its convenience, non-invasiveness, high specificity and it overcomes temporal-spatial heterogeneity. Therefore, this review summarizes the current evidence on liquid biopsies in digestive tract cancers in relation to diagnosis and prognosis.

Long non-coding RNAs towards precision medicine in gastric cancer: early diagnosis, treatment, and drug resistance

Gastric cancer is a deadly disease and remains the third leading cause of cancer-related death worldwide. The 5-year overall survival rate of patients with early-stage localized gastric cancer is more than 60%, whereas that of patients with distant metastasis is less than 5%. Surgical resection is the best option for early-stage gastric cancer, while chemotherapy is mainly used in the middle and advanced stages of this disease, despite the frequently reported treatment failure due to chemotherapy resistance. Therefore, there is an unmet medical need for identifying new biomarkers for the early diagnosis and proper management of patients, to achieve the best response to treatment. Long non-coding RNAs (lncRNAs) in body fluids have attracted widespread attention as biomarkers for early screening, diagnosis, treatment, prognosis, and responses to drugs due to the high specificity and sensitivity. In the present review, we focus on the clinical potential of lncRNAs as biomarkers in liquid biopsies in the diagnosis and prognosis of gastric cancer. We also comprehensively discuss the roles of lncRNAs and their molecular mechanisms in gastric cancer chemoresistance as well as their potential as therapeutic targets for gastric cancer precision medicine.

Plasma Exosomal Long Noncoding RNA lnc-SLC2A12-10:1 as a Novel Diagnostic Biomarker for Gastric Cancer

Purpose

Exosomes participate in cellular communications by transmitting active molecules, including long noncoding RNAs (lncRNAs) and are regarded as suitable candidates for disease diagnosis. This study aimed to identify gastric cancer (GC)-specific exosomal lncRNA and investigate the potential diagnostic value of plasma exosomal lncRNA in GC.

Patients and Methods

Exosomes from the culture media (CM) of four GC cells (GCCs) and human gastric epithelial cells were isolated. Exosomal RNA was extracted, and lncRNA microarray assay was performed to identify GC-specific exosomal lncRNAs. The expression levels of the candidate exosomal lncRNAs were validated in 120 subjects via quantitative reverse transcription PCR (qRT-PCR). The receiver operating characteristic (ROC) curve and area under curve were used to estimate the diagnostic capacity. We investigated the potential relationship between plasma exosomal lncRNA expression and the clinicopathological parameters of GC.

Results

A total of 199 exosomal lncRNAs were expressed at considerable higher levels in GCCs than those in normal controls, among which the top 10 upregulated lncRNAs were selected for further validation in cell, CM, and plasma. qRT-PCR revealed that lnc-SLC2A12-10:1 was remarkably upregulated in exosomes derived from patients with GC and GCCs. The area under the ROC curve was 0.776, which was higher than the diagnostic accuracies of CEA, CA 19-9, and CA72-4. The expression level of exosomal lnc-SLC2A12-10:1 was also significantly correlated with tumor size, TNM stage, lymph node metastasis, and degree of differentiation. The postoperative expression levels of exosomal lnc-SLC2A12-10:1 were lower compared with those of preoperative levels.

Conclusion

Our study suggested that exosomal lnc-SLC2A12-10:1 may be a potential noninvasive biomarker for the diagnosis and prognosis monitoring of GC. Further large-scale studies are necessary to validate its performance in GC progression.

Exosome-transmitted lncRNA UFC1 promotes non-small-cell lung cancer progression by EZH2-mediated epigenetic silencing of PTEN expression

Long non-coding RNAs (LncRNAs) have been suggested as important regulators of cancer development and progression in non-small cell lung cancer (NSCLC). Nevertheless, the biological roles and clinical significance of lncRNA UFC1 in NSCLC remain unclear. We detected the expression of UFC1 in tumor tissues, serum, and serum exosomes of NSCLC patients by qRT-PCR. Gene overexpression or silencing were used to examine the biological roles of UFC1 in NSCLC. RNA immunoprecipitation and ChIP assays were performed to evaluate the interaction between UFC1 and enhancer of zeste homolog 2 (EZH2) and the binding of EZH2 to PTEN gene promoter. Rescue study was used to access the importance of PTEN regulation by UFC1 in NSCLC progression. UFC1 expression was upregulated in tumor tissues, serum, and serum exosomes of NSCLC patients and high level of UFC1 was associated with tumor infiltration. UFC1 knockdown inhibited NSCLC cell proliferation, migration and invasion while promoted cell cycle arrest and apoptosis. UFC1 overexpression led to the opposite effects. Mechanistically, UFC1 bound to EZH2 and mediated its accumulation at the promoter region of PTEN gene, resulting in the trimethylation of H3K27 and the inhibition of PTEN expression. UFC1 knockdown inhibited NSCLC growth in mouse xenograft tumor models while the simultaneous depletion of PTEN reversed this effect. NSCLC cells derived exosomes could promote NSCLC cell proliferation, migration and invasion through the transfer of UFC1. Moreover, Exosome-transmitted UFC1 promotes NSCLC progression by inhibiting PTEN expression via EZH2-mediated epigenetic silencing. Exosome-mediated transmit of UFC1 may represent a new mechanism for NSCLC progression and provide a potential marker for NSCLC diagnosis.

Determination of Serum Exosomal H19 as a Noninvasive Biomarker for Breast Cancer Diagnosis

Purpose

There is an urgent need for new biomarkers for the diagnosis of breast cancer. Exosomes can communicate with cells through transport molecules, including long-chain noncoding RNA (lncRNA), which is considered as a promising noninvasive biomarker. Here, we aimed to determine the potential of long noncoding RNA (lncRNA) H19 in the circulating exosomes for the diagnosis of breast cancer (BC).

Materials and Methods

We measured the levels of lncRNA H19 in serum-derived exosomes from patients with breast cancer (BC) or benign breast disease (BBD) and healthy subjects, using quantitative real-time PCR. H19 levels were also measured for pre-operative and post-operative patients. Receiver operating characteristic curve was constructed, and the area under the curve (AUC) was calculated to determine the applicability of exosomal H19 levels as biomarkers in BC. The relationship between H19 relative expression and clinical features of BC patients was also analyzed.

Results

Exosomal H19 expression levels were upregulated in patients with BC compared to that in patients with BBD and healthy controls (BC vs BBD, P < 0.001; BC vs healthy subjects, P < 0.001). The median serum exosomal H19 levels were significantly lower in post-operative than that in the pre-operative patients (P < 0.001). The AUC for exosomal H19 analysis was 0.870 (95% CI: 0.774–0.966) with a sensitivity of 87.0% and specificity of 70.6%, which was higher than the AUCs for CA15-3 and CEA, ie, 0.822 and 0.811, respectively. Moreover, exosomal H19 expression levels were associated with lymph node metastasis (P = 0.039), distant metastasis (P = 0.008), TNM stages (P = 0.022), ER (P=0.009), PR (P = 0.018), and Her-2 (P = 0.021).

Conclusion

Our results indicated that serum exosomal H19 acts as a novel biomarker for the diagnosis of BC.

RNA sequencing reveals the long noncoding RNA and mRNA profiles and identifies long non-coding RNA TSPAN12 as a potential microvascular invasion-related biomarker in hepatocellular carcinoma

Emerging evidence demonstrates that abnormally expressed long noncoding RNAs (lncRNAs) are involved in the progression of various cancers. However, the expression profiles and functions of lncRNAs in hepatocellular carcinoma (HCC) with microvascular invasion (MVI) remain largely unknown. In this study, we revealed the differential expression profiles of lncRNA and messenger RNA in four pairs of HCC with MVI and adjacent nontumor liver tissues by using high-throughput RNA sequencing. Among these dysregulated lncRNAs, lnc-TSPAN12 was the most significantly upregulated lncRNA in HCC. The results of real time-PCR showed that lnc-TSPAN12 was highly expressed in HCC, including HCC with MVI, and its high expression was associated with unfavorable clinicopathological features and poor prognosis. Moreover, multivariate Cox regression analysis verified that lnc-TSPAN12 was an independent prognostic predictor for overall and recurrence-free survival. Receiver operating characteristic curve analysis indicated that lnc-TSPAN12 could serve as a potential diagnostic biomarker for HCC with MVI. In addition, a loss-of-function experiment demonstrated that lnc-TSPAN12 knockdown inhibited HCC cell migration and invasion in vitro. Our findings suggest that lnc-TSPAN12 may function as an oncogene in HCC progression and could serve as a novel diagnostic/prognostic biomarker and potential therapeutic target for HCC with MVI.

RNA sequencing of exosomes revealed differentially expressed long noncoding RNAs in early-stage esophageal squamous cell carcinoma and benign esophagitis

Aim: To explore the roles of exosomal long noncoding RNAs (lncRNAs) in early-stage esophageal squamous cell carcinoma (ESCC) and benign esophagitis. Materials & methods: Exosomal lncRNAs were analyzed using RNA-seq and validated by quantitative real-time PCR, loss-of-function, co-culture and RNA pulldown assays. Results: Exosomal lncRNAs displayed tighter tissue-specificity, higher expression level and lower splicing efficiency than that of mRNAs. A total of 152 exosomal lncRNAs were differentially expressed between ESCC and controls. A total of 124 exosomal lncRNAs were dysregulated between ESCC and esophagitis. Knockdown of 13 ESCC-associated lncRNAs modified proliferation, migration, and apoptosis of ESCC cells. A novel lncRNA RP5-1092A11.2 was highly expressed in ESCC-derived exosomes, ESCC cells and tumor tissues. Exosomes released from RP5-1092A11.2-knockdown cells inhibited ESCC cell proliferation. Conclusion: Dysregulated exosomal lncRNAs were functionally associated with different disease status in esophagus.

Exploration of Serum Exosomal LncRNA TBILA and AGAP2-AS1 as Promising Biomarkers for Diagnosis of Non-Small Cell Lung Cancer

Non-small cell lung cancer is the most common type of cancer with a poor prognosis, and development of an effective diagnostic method is urgently needed. Exosomal lncRNAs, a class of transcripts longer than 200 nucleotides packaged into exosomes, have been defined as an ideal diagnostic biomarker for cancer. However, little is known about the clinical utility of exosomal lncRNAs in NSCLC. Here, we aimed to identify exosomal lncRNAs as promising biomarkers for NSCLC diagnosis. First, serum exosomes from NSCLC patients were successfully isolated by a polymer precipitation kit and then identified by TEM, NTA and western blot analysis. A total of nine candidate lncRNAs were detected by qRT-PCR in a training set. The two exosomal lncRNA TBILA and AGAP2-AS1 were screened out for the higher levels in NSCLC patients than that of healthy controls in a validation set. And there was a significant positive correlation between these exosomal lncRNAs levels and tumor size, lymph node metastasis and TNM stage. Additionally, we validated that these exosomal lncRNAs were stable in serum. Next, we evaluated the diagnostic efficiency of exosomal lncRNAs in NSCLC patients by ROC curve analysis. The data showed that individual TBILA or AGAP2-AS1 exhibited better diagnostic efficiency in NSCLC patients with different tumor pathologic subtypes and early stage, whereas the combination of lncRNAs did not provide better results than individual lncRNAs. Notably, the combination of two exosomal lncRNAs and the serum tumor biomarker Cyfra21-1 widely used in clinical practices further improved the diagnostic accuracy for NSCLC patients. This study suggests that exosomal lncRNA TBILA and AGAP2-AS1 may be promising biomarkers for diagnosis of NSCLC.

Exosome and Secretion: Action On?

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

Advances in the study of exosomal lncRNAs in tumors and the selection of research methods

Exosomes are endosome-derived extracellular vesicles that are released upon the fusion of multivesicular bodies with the plasma membrane. These vesicles contain proteins, lipids, and nucleic acids and are found in various human body fluids. Exosomes can transfer bioactive molecules to nearby or distant recipient cells, thereby affecting their function. Recently, exosomes have gained importance as a medium of communication between tumor cells. An increasing number of studies have found that non-coding RNAs in tumor cell-derived exosomes can regulate tumor microenvironments, inhibit immune cell function, promote the growth and invasion of tumor cells, and impart resistance to chemicals in tumor cells. In this review, we focus on the effects of exosomal long non-coding RNAs (lncRNAs) on tumors. As exosomes and their parent cells have similar biological characteristics and coated lncRNAs can exist stably in vivo without being degraded by RNases, exosomal lncRNAs have emerged as novel non-invasive tumor biomarkers for use in the early diagnosis and evaluation of prognosis of tumors. Advancements in the field have led to the development of a variety of techniques in exosomal non-coding RNA research. Currently, most methods include the separation and purification of exosomes, followed by RNA extraction, reverse transcription, and subsequent analyses; thus, these processes are very tedious and vulnerable to contamination and could lead to inaccurate and inconsistent results. Thus, there has been an increase in the development of detection methods for exosomal RNAs. Here, we discuss the existing research methods, their advantages and disadvantages, and a few new techniques.