Exosomal FMR1-AS1 facilitates maintaining cancer stem-like cell dynamic equilibrium via TLR7/NFκB/c-Myc signaling in female esophageal carcinoma

AS1411 and EpDT3-conjugated silver nanotriangle-mediated photothermal therapy for breast cancer and cancer stem cells

Aim: This study aimed to construct AS1411 and EpDT3-conjugated PEGylated silver nanotriangles (AENTs) and assess their ability to target breast cancer and cancer stem cells, as well as the antitumor and antimetastatic effects of AENT-mediated photothermal therapy. Materials & methods: AENTs were constructed and characterized. The targeting properties, as well as antitumor and antimetastatic activities, were evaluated in MDA-MB-231 breast cancer cells, cancer stem cells and breast cancer-bearing mice. Results: AENTs displayed excellent targeting property to breast cancer cells and cancer stem cells. AENT-mediated photothermal therapy greatly inhibited (>45%) the migration and invasion of breast cancer cells, as well as tumor growth and lung metastasis in the mice. Conclusion: AENT-mediated photothermal therapy might be an effective strategy for the treatment of breast cancer.

GOLPH3/CKAP4 promotes metastasis and tumorigenicity by enhancing the secretion of exosomal WNT3A in non-small-cell lung cancer

Cancer metastasis is the main cause of mortality associated with non-small-cell lung cancer (NSCLC), accounting for up to 70% of deaths among patients. The mechanisms underlying distal metastasis remain largely unknown. Golgi phosphoprotein 3 (GOLPH3) correlates negatively with overall survival in multiple tumors. In this study, we evaluated the function of GOLPH3 in NSCLC distal metastasis. GOLPH3 was expressed at high levels in samples from patients with NSCLC and was positively associated with clinicopathologic characteristics including clinical stage (P < 0.001), T (P = 0.001), N (P = 0.007), and M (P = 0.001) classification. Functionally, Transwell and wound-healing assays suggested that GOLPH3 overexpression enhances NSCLC cell migration and invasion abilities. Tumor-sphere formation and flow cytometry assays demonstrated that GOLPH3 overexpression enhances a stem cell-like phenotype of NSCLC cells. Metastasis models established by tail vein and intracardiac injection confirmed the pro-metastatic function of GOLPH3 in vivo. A subcutaneous tumor formation model confirmed that GOLPH3 overexpression increased the tumorigenicity of NSCLC cells. Mechanistically, gene set enrichment analysis revealed a positive association of GOLPH3 mRNA expression with WNT-activated gene signatures. Luciferase-reporter and nuclear extract assays showed that GOLPH3 overexpression enhances metastasis and tumorigenicity through activation of the WNT/β-catenin pathway. Immunoprecipitation-mass spectrometry and gene ontology analysis demonstrated that GOLPH3 interacts with cytoskeleton-associated protein 4 (CKAP4) in exosome-mediated distal metastasis. We found that GOLPH3 decreased the amount of plasma membrane-localized CKAP4 and increased the amount of exosome-localized CKAP4 to promote the formation of CKAP4-containing exosomes. Furthermore, we demonstrated that CKAP4 binds exosomal WNT3A to enhance its secretion. Therefore, the GOLPH3/CKAP4 axis plays a crucial role in promoting exosomal-WNT3A secretion to enhance and maintain the stem-like phenotype and metastasis in NSCLC, thus indicating the therapeutic potential of GOLPH3 in patients with NSCLC metastasis.

Therapeutic Potential of the Cyclin-Dependent Kinase Inhibitor Flavopiridol on c-Myc Overexpressing Esophageal Cancer

Tumors with elevated c-Myc expression often exhibit a highly aggressive phenotype, and c-Myc amplification has been shown to be frequent in esophageal cancer. Emerging data suggests that synthetic lethal interactions between c-Myc pathway activation and small molecules inhibition involved in cell cycle signaling can be therapeutically exploited to preferentially kill tumor cells. We therefore investigated whether exploiting elevated c-Myc expression is effective in treating esophageal cancer with the CDK inhibitor flavopiridol. We found frequent overexpression of c-Myc in human esophageal cancer cell lines and tissues. c-Myc overexpression correlated with accelerated esophageal cancer subcutaneous xenograft tumor growth. Esophageal cancer cells with elevated c-Myc expression were found preferentially more sensitive to induction of apoptosis by the CDK inhibition flavopiridol compared to esophageal cancer cells with lower c-Myc expression. In addition, we observed that flavopiridol alone or in combination with the chemotherapeutic agent nanoparticle albumin-bound paclitaxel (NPT) or in combinations with the targeted agent BMS-754807 significantly inhibited esophageal cancer cell proliferation and subcutaneous xenograft tumor growth while significantly enhancing overall mice survival. These results indicate that aggressive esophageal cancer cells with elevated c-Myc expression are sensitive to the CDK inhibitor flavopiridol, and that flavopiridol alone or in combination can be a potential therapy for c-Myc overexpressing esophageal cancer.

LINC00514 promotes lipogenesis and tumor progression in esophageal squamous cell carcinoma by sponging miR‑378a‑5p to enhance SPHK1 expression

Increasing evidence has demonstrated that long non‑coding RNAs serve pivotal roles in tumor development, progression, metastasis and metabolism. However, to the best of our knowledge, the roles and molecular mechanisms of long intergenic nonprotein‑coding RNA 00514 (LINC00514) in esophageal squamous cell carcinoma (ESCC) remain unknown. The present study found that LINC00514 and sphingosine kinase 1 (SPHK1) were both upregulated in ESCC tissues and cells, and their high expression levels were closely associated with Tumor‑Node‑Metastasis stage, lymph node metastasis and poor prognosis of patients with ESCC. Functionally, knockdown of LINC00514 inhibited cell proliferation and invasion, and led to the downregulation of lipogenesis‑related proteins, including SPHK1, fatty acid synthase, acetyl‑coenzyme (Co)A carboxylase α and stearoyl‑CoA desaturase 1, whereas LINC00514 overexpression promoted cell proliferation and invasion in ESCC KYSE150 and KYSE30 cells, and upregulated expression of lipogenesis‑related proteins. Mechanistically, LINC00514 functioned as a competing endogenous RNA by sponging microRNA (miR)‑378a‑5p, resulting in the upregulation of SPHK1, which was accompanied by the activation of lipogenesis‑related pathways, to promote ESCC cell proliferation and invasion. Taken together, these findings suggest that LINC00514 may participate in ESCC lipogenesis, and targeting the LINC00514/miR‑378a‑5p/SPHK1 signaling axis may be a novel and promising therapeutic strategy for management of patients with ESCC.

Small Extracellular Vesicles in the Development, Diagnosis, and Possible Therapeutic Application of Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) persists among the most lethal and broad-spreading malignancies in China. The exosome is a kind of extracellular vesicle (EV) from about 30 to 200 nm in diameter, contributing to the transfer of specific functional molecules, such as metabolites, proteins, lipids, and nucleic acids. The paramount role of exosomes in the formation and development of ESCC, which relies on promoting intercellular communication in the tumor microenvironment (TME), is manifested with immense amounts. Tumor-derived exosomes (TDEs) participate in most hallmarks of ESCC, including tumorigenesis, invasion, angiogenesis, immunologic escape, metastasis, radioresistance, and chemoresistance. Published reports have delineated that exosome-encapsulated cargos like miRNAs may have utility in the diagnosis, as prognostic biomarkers, and in the treatment of ESCC. This review summarizes the function of exosomes in the neoplasia, progression, and metastasis of ESCC, which improves our understanding of the etiology and pathogenesis of ESCC, and presents a promising target for early diagnostics in ESCC. However, recent studies of exosomes in the treatment of ESCC are sparse. Thus, we introduce the advances in exosome-based methods and indicate the possible applications for ESCC therapy in the future.

Exosomal long non-coding RNAs: Emerging players in cancer metastasis and potential diagnostic biomarkers for personalized oncology

Metastasis is a major challenge in the treatment of cancer. Exosomes are a class of small extracellular vesicles (EVs) that play critical roles in several human diseases, especially cancer, by transferring information (e.g., DNA, RNA, and protein) via cell-to-cell communication. Numerous recent studies have shown that exosomal long non-coding RNAs (lncRNAs) play crucial regulatory roles in cancer metastasis in the tumor microenvironment by altering the expression of several key signaling pathways and molecules. Due to their specificity and sensitivity, exosomal lncRNAs have potential as novel tumor markers and therapeutic targets in the treatment of cancer metastasis. In this review, we aim to summarize the roles of exosomal lncRNAs in cancer metastasis, the mechanisms underlying their roles, and their potential clinical applications.

Long noncoding RNA KCNMB2-AS1 promotes the development of esophageal cancer by modulating the miR-3194-3p/PYGL axis

Esophageal cancer (ESCA), as a common cancer worldwide, is a main cause of cancer-related mortality. Comprehensive studies on molecular mechanism of ESCA have been carried out. Though numerous long noncoding RNAs (lncRNAs) was reported to participate in the occurrence and development of ESCA, the potential role of lncRNA potassium calcium-activated channel subfamily M regulatory beta subunit 2 (KCNMB2) antisense RNA 1 (KCNMB2-AS1) in ESCA remains to be discovered. This study intends to investigate the detailed function and molecular mechanism of KCNMB2-AS1 in ESCA. Gene expression was evaluated by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Cell proliferation was examined by Cell Counting Kit-8 (CCK-8) assay and colony formation assay. Cell invasion and migration were measured by wound healing assay and Transwell assay. Luciferase reporter assay was adopted to validate the interaction between KCNMB2-AS1 and miR-3194-3p. Western blotting was performed to assess protein levels. We discovered that KCNMB2-AS1 was significantly upregulated in ESCA. KCNMB2-AS1 downregulation suppressed the growth, invasion, migration and stemness of ESCA cells. KCNMB2-AS1 bound with miR-3194-3p, and glycogen phosphorylase L (PYGL) was a direct target of miR-3194-3p. KCNMB2-AS1 upregulated PYGL expression by directly binding with miR-3194-3p. Additionally, PYGL overexpression abolished the inhibitory influence of KCNMB2-AS1 depletion on ESCA cell behaviors. Collectively, lncRNA KCNMB2-AS1 promotes ESCA development through targeting the miR-3194-3p/ PYGL axis, which might provide theoretical basis to explore novel biomarkers for ESCA treatment.

The Significance of Exosomes in Pathogenesis, Diagnosis, and Treatment of Esophageal Cancer

Esophageal cancer is one of the most common malignancy in China with high mortality. Understanding pathogenesis and identifying early diagnosis biomarkers can significantly improve the prognosis of patients with esophageal cancer. Exosomes are small vesicular structures containing a variety of components (including DNA, RNA, and proteins) mediating cell-to-cell material exchange and signal communication. Growing evidences have shown that exosomes and its components are involved in growth, metastasis and angiogenesis in cancer, and could also be used as diagnostic and prognostic markers. In this review, we summarized recent progress to elucidate the significance of exosomes in the esophageal cancer progression, microenvironment remodeling, therapeutic resistance, and immunosuppression. We also discuss the utility of exosomes as diagnostic and prognostic biomarkers and therapeutic tool in esophageal cancer.

Linc00941 regulates esophageal squamous cell carcinoma via functioning as a competing endogenous RNA for miR-877-3p to modulate PMEPA1 expression

Esophageal squamous cell carcinoma (ESCC) represents one of the most common malignancies and is the fifth leading cause of cancer-related deaths. Long intergenic non-coding RNAs (lincRNAs) have been suggested to be dysregulated in various types of cancers, and a growing number of lincRNAs have been implicated to be functional in the ESCC progression. In this study, we examined the role of linc00941 in the ESCC progression and explored the underlying molecular mechanisms. The bioinformatics analysis identified the up-regulation of linc00941 in the ESCC tissues. Further in vitro studies showed that linc00941 was up-regulated in ESCC cell lines. The loss-of-function studies demonstrated that linc00941 knockdown suppressed ESCC cell proliferation, invasion and migration, and also suppressed the in vivo tumor growth. Furthermore, bioinformatics prediction along with luciferase reporter assay and RNA immunoprecipitation assay implied that linc00941 acted as a competing endogenous RNA for miR-877-3p, and linc00941 regulated ESCC cell progression via at least targeting miR-877-3p. Subsequently, miR-877-3p targeted prostate transmembrane protein, androgen induced 1 (PMEPA1) 3' untranslated region and repressed PMEPA1 expression in ESCC cells; overexpression of PMEPA1 attenuated the inhibitory effects of linc00941 knockdown on the ESCC cell progression. Linc00941 knockdown suppressed epithelial-mesenchymal transition (EMT) via targeting miR-877-3p/PMEPA1 axis in ESCC cells. In conclusion, our results indicated the oncogenic role of linc00941 in ESCC, and knockdown of linc00941 suppressed ESCC cell proliferation, invasion, migration and EMT via interacting with miR-877-3p/PMEPA1 axis.

Dissecting the single-cell transcriptome network underlying esophagus non-malignant tissues and esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is among the most prevalent causes of cancer-related death in adults. Tumor microenvironment (TME) has been associated with therapeutic failure and lethal outcomes for patients. However, published reports on the heterogeneity and TME in ESCC are scanty.

METHODS

Five tumor samples and five corresponding non-malignant samples were subjected to scRNA-seq analysis. Bulk RNA sequencing data were retrieved in publicly available databases.

FINDINGS

From the scRNA-seq data, a total of 128,688 cells were enrolled for subsequent analyses. Gene expression and CNV status exhibited high heterogeneity of tumor cells. We further identified a list of tumor-specific genes and four malignant signatures, which are potential new markers for ESCC. Metabolic analysis revealed that energy supply-related pathways are pivotal in cancer metabolic reprogramming. Moreover, significant differences were found in stromal and immune cells between the esophagus normal and tumor tissues, which promoted carcinogenesis at both cellular and molecular levels in ESCC. Immune checkpoints, regarded as potential targets for immunotherapy in ESCC were significantly highly expressed in ESCC, including LAG3 and HAVCR2. Eventually, we constructed a cell-to-cell communication atlas based on cancer cells and immune cells and performed the flow cytometry, qRT-PCR, immunofluorescence, and immunohistochemistry analyses to validate the results.

INTERPRETATION

This study demonstrates a widespread reprogramming across multiple cellular elements within the TME in ESCC, particularly in transcriptional states, cellular functions, and cell-to-cell interactions. The findings offer an insight into the exploration of TME and heterogeneity in the ESCC and provide new therapeutic targets for its clinical management in the future.

FUNDING

The work was supported by the Shanghai Pujiang Program (2020PJD009) and Research Development Fund of Zhongshan Hospital, Fudan University (2019ZSFZ002 and 2019ZSFZ19).

Exosomal circRNA in Digestive System Tumors: The Main Player or Coadjuvants?

Exosomes are a type of extracellular microvesicles with a diameter of 40–160 nm. Circular RNA (circRNA) is a type of closed circular RNA molecule that is highly conserved in evolution. Exosomal circRNA plays a vital role in the proliferation, invasion, migration, and drug resistance of digestive system tumors. In this study, we used The Cancer Genome Atlas (TCGA) database, UALCAN, Python crawler, miRTargetLink Human, Database for Annotation, Visualization, and Integrated Discovery (DAVID), micBioinformatic online tool, and Cytoscape software (3.7.1). The results showed that circ-RanGAP1 in gastric cancer, circUHRF1 in hepatocellular carcinoma, and circFMN2 in colorectal cancer regulate the malignant behavior of tumors and affect the expression of their host gene through sponging miR-877-3p, miR-449c-5p, and miR-1182, respectively. Twenty exosomal circRNAs regulate 6,570 target genes through sponging 23 miRNAs. Firstly, 270 of those target genes are regulated by two or more miRNAs, which are highly correlated with 83 tumor-related pathways and six Kyoto Encyclopedia of Genes and Genomes pathways. Secondly, 1,146 target genes were significantly differentially expressed in corresponding digestive system tumors, and functional enrichment analysis revealed that 78 of those were involved in 20 cancer-related pathways. In short, the bioinformatics analysis showed that these exosomal circRNAs are stably expressed in body fluids, and regulate the occurrence and development of gastric cancer, hepatocellular carcinoma, colorectal cancer, and other digestive system tumors through sponging miRNAs. Exosomal circRNAs may be used as biomarkers for the diagnosis of disease and identification of effective therapeutic targets in the future, as well as improve the prognosis of patients with digestive system tumors.

Exosomal SNHG16 secreted by CSCs promotes glioma development via TLR7

Background

Glioma is one of the most common central nervous system malignant tumors, accounting for 45~60% of adult intracranial tumors. However, the clinical treatment of glioma is limited. It is of great significance to seek new therapeutic methods for glioma via gene therapy.

Methods

Long non-coding RNA (lncRNA) SNHG16 expression level was measured by microarray and qRT-PCR assay; ISH was used to identify the location of SNHG16. Cancer stem cells (CSCs) were separated from glioma tissues and identified using immunofluorescence. Exosomes were isolated from CSCs and cancer cells and identified by TEM and western blot. MTT, wound healing, transwell, and colony formation assay were performed to explore the role of SNHG16 or si-SNHG16 from CSCs on progression of glioma cells. RIP was used to verify the interaction between SNHG16 and TLR7. The experiment of Xenograft used for exploring the function of SNHG16/ TLR7/MyD88/NFκB/c-Myc on growth on glioma in vivo.

Results

Microarray assay showed long non-coding RNA (lncRNA) SNHG16 was upregulated in glioma. Followed qRT-PCR also showed an increase of SNHG16 in glioma tissues; high expression of SNHG16 indicated a poor prognosis in glioma patients. Interestingly, SNHG16 was packaged into exosomes and derived from CSCs. Functional analysis showed exo-SNHG16 secreted by CSCs promoted the progression of glioma cell lines SHG44 and U251. Furthermore, SNHG16 interacted with TLR7 and activated NFκB/c-Myc signaling in glioma cells. And the silencing of TLR7 inhibited the progression of SHG44 and U251 cells by exo-SNHG16 from CSCs. In vivo tumorigenesis experiments showed that exo-SNHG16 induced glioma progression by activating TLR7/MyD88/NFκB/c-Myc signaling.

Conclusion

Our study suggested CSC-derived exo-SNHG16 promoted cancer progression by activating TLR7/MyD88/NFκB/c-Myc signaling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02393-8.

Autophagy and Extracellular Vesicles, Connected to rabGTPase Family, Support Aggressiveness in Cancer Stem Cells

Even though cancers have been widely studied and real advances in therapeutic care have been made in the last few decades, relapses are still frequently observed, often due to therapeutic resistance. Cancer Stem Cells (CSCs) are, in part, responsible for this resistance. They are able to survive harsh conditions such as hypoxia or nutrient deprivation. Autophagy and Extracellular Vesicles (EVs) secretion are cellular processes that help CSC survival. Autophagy is a recycling process and EVs secretion is essential for cell-to-cell communication. Their roles in stemness maintenance have been well described. A common pathway involved in these processes is vesicular trafficking, and subsequently, regulation by Rab GTPases. In this review, we analyze the role played by Rab GTPases in stemness status, either directly or through their regulation of autophagy and EVs secretion.

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.

Exosomes and Cancer Stem Cells in Cancer Immunity: Current Reports and Future Directions

Cancer stem cells (CSCs), which have the capacity to self-renew and differentiate into various types of cells, are notorious for their roles in tumor initiation, metastasis, and therapy resistance. Thus, underlying mechanisms for their survival provide key insights into developing effective therapeutic strategies. A more recent focus has been on exosomes that play a role in transmitting information between CSCs and non-CSCs, resulting in activating CSCs for cancer progression and modulating their surrounding microenvironment. The field of CSC-derived exosomes (CSCEXs) for different types of cancer is still under exploration. A deeper understanding and further investigation into CSCEXs’ roles in tumorigenicity and the identification of novel exosomal components are necessary for engineering exosomes for the treatment of cancer. Here, we review the features of CSCEXs, including surface markers, cargo, and biological or physiological functions. Further, reports on the immunomodulatory effects of CSCEXs are summarized, and exosome engineering for CSC-targeting is also discussed.

The emerging role of long noncoding RNAs in esophageal carcinoma: from underlying mechanisms to clinical implications

Long noncoding RNAs (lncRNAs), a type of transcriptional product more than 200 nucleotides in length, have emerged as crucial regulators in human cancers. Accumulating data have recently indicated relationships between lncRNAs and esophageal carcinoma (EC). Of note, lncRNAs act as decoys/sponges, scaffolds, guides, and signals to regulate the expression of oncogenes or tumor suppressors at epigenetic, post-transcriptional, and protein levels, through which they exert their unique EC-driving or EC-suppressive functions. Moreover, the features of EC-related lncRNAs have been gradually exploited for developing novel diagnostic and therapeutic strategies in clinical scenarios. LncRNAs have the potential to be used as diagnostic and prognostic indicators individually or in combination with other clinical variables. Beyond these, although the time is not yet ripe, therapeutically targeting EC-related lncRNAs via gene editing, antisense oligonucleotides, RNA interference, and small molecules is likely one of the most promising therapeutic strategies for the next generation of cancer treatment. Herein, we focus on summarizing EC-driving/suppressive lncRNAs, as well as discussing their different features regarding expression profiles, modes of action, and oncological effects. Moreover, we further discuss current challenges and future developing possibilities of capitalizing on lncRNAs for EC early diagnosis and treatment.

The key roles of cancer stem cell-derived extracellular vesicles

Cancer stem cells (CSCs), the subpopulation of cancer cells, have the capability of proliferation, self-renewal, and differentiation. The presence of CSCs is a key factor leading to tumor progression and metastasis. Extracellular vesicles (EVs) are nano-sized particles released by different kinds of cells and have the capacity to deliver certain cargoes, such as nucleic acids, proteins, and lipids, which have been recognized as a vital mediator in cell-to-cell communication. Recently, more and more studies have reported that EVs shed by CSCs make a significant contribution to tumor progression. CSCs-derived EVs are involved in tumor resistance, metastasis, angiogenesis, as well as the maintenance of stemness phenotype and tumor immunosuppression microenvironment. Here, we summarized the molecular mechanism by which CSCs-derived EVs in tumor progression. We believed that the fully understanding of the roles of CSCs-derived EVs in tumor development will definitely provide new ideas for CSCs-based therapeutic strategies.

A Novel Long Non-Coding RNA lnc030 Maintains Breast Cancer Stem Cell Stemness by Stabilizing SQLE mRNA and Increasing Cholesterol Synthesis

Cancer stem cells (CSCs) are considered the roots of cancer metastasis and recurrence (CSCs), due in part to their self-renewal and therapy resistance properties. However, the underlying mechanisms for the regulation of CSC stemness are poorly understood. Recently, increasing evidence shows that long non-coding RNAs (lncRNAs) are critical regulators for cancer cell function in various malignancies including breast cancer, but how lncRNAs regulate the function of breast cancer stem cells (BCSCs) remains to be determined. Herein, using lncRNA/mRNA microarray assays, a novel lncRNA (named lnc030) is identified, which is highly expressed in BCSCs in vitro and in vivo, as a pivotal regulator in maintaining BCSC stemness and promoting tumorigenesis. Mechanistically, lnc030 cooperates with poly(rC) binding protein 2(PCBP2) to stabilize squalene epoxidase (SQLE) mRNA, resulting in an increase of cholesterol synthesis. The increased cholesterol in turn actives PI3K/Akt signaling, which governs BCSC stemness. In summary, these findings demonstrate that a new, lnc030-based mechanism for regulating cholesterol synthesis and stemness properties of BCSCs. The lnc030-SQLE-cholesterol synthesis pathway may serve as an effective therapeutic target for BCSC elimination and breast cancer treatment.

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.

Non-coding RNA derived from extracellular vesicles in cancer immune escape: Biological functions and potential clinical applications

The tumor microenvironment represents a dynamically composed matrix into which cancer cells and many other cell types are embedded to form organ-like structures. The tumor immune microenvironment (TIME), composed of immune cells, is an inseparable part of the tumor microenvironment. Extracellular vesicles (EVs) participate in the occurrence and development of tumors by delivering various biologically active molecules between cells; their role in cancer immune escape in particular has been widely proven. EVs can carry a wide array of cargo, such as non-coding RNAs (ncRNAs), including miRNAs, lncRNAs, and circRNAs, which are selectively loaded by EVs, secreted, and transported to participate in the proliferation of immune cells. Hence, strategies to specifically target EV-ncRNAs could be attractive therapeutic options. In this review, we summarize the current research on the role of EV-ncRNAs in cancer immune escape, and discuss the latest research on the function and regulation mechanism of EV-ncRNAs in cancer immune escape, highlighting and elucidating the potential clinical applications of EV-ncRNAs, including in diagnosis and immunotherapy.

MiR-624-3p Promotes Esophageal Squamous Cell Carcinoma Progression via Targeting Phosphatase and Tensin Homologue

The emerging role of miRNA as regulators in esophageal squamous cell carcinoma (ESCC) progression has aroused great attention recently. In this study, the effects of miR-624-3p in ESCC progression were explored through cell proliferation, colony formation, cell cycle, and apoptosis analyses. Results showed that increased expression of miR-624-3p enhanced cancer cell viability, proliferation, migration, and invasion but inhibited apoptosis in ESCC. Moreover, luciferase reporter assay demonstrated that miR-624-3p bound to the 3'-untranslated region of phosphatase and tensin homologue (PTEN). Further study showed that miR-624-3p exerted its tumor promoting role through targeting PTEN. Taken together, these results elucidate the regulatory role of miR-624-3p in ESCC progression, shedding light on its possible clinical application in ESCC treatment.

Epigenetic Mechanisms of LncRNAs Binding to Protein in Carcinogenesis

Simple Summary

The functional analysis of lncRNA, which has recently been investigated in various fields of biological research, is critical to understanding the delicate control of cells and the occurrence of diseases. The interaction between proteins and lncRNA, which has been found to be a major mechanism, has been reported to play an important role in cancer development and progress. This review thus organized the lncRNAs and related proteins involved in the cancer process, from carcinogenesis to metastasis and resistance to chemotherapy, to better understand cancer and to further develop new treatments for it. This will provide a new perspective on clinical cancer diagnosis, prognosis, and treatment.

Abstract

Epigenetic dysregulation is an important feature for cancer initiation and progression. Long non-coding RNAs (lncRNAs) are transcripts that stably present as RNA forms with no translated protein and have lengths larger than 200 nucleotides. LncRNA can epigenetically regulate either oncogenes or tumor suppressor genes. Nowadays, the combined research of lncRNA plus protein analysis is gaining more attention. LncRNA controls gene expression directly by binding to transcription factors of target genes and indirectly by complexing with other proteins to bind to target proteins and cause protein degradation, reduced protein stability, or interference with the binding of other proteins. Various studies have indicated that lncRNA contributes to cancer development by modulating genes epigenetically and studies have been done to determine which proteins are combined with lncRNA and contribute to cancer development. In this review, we look in depth at the epigenetic regulatory function of lncRNAs that are capable of complexing with other proteins in cancer development.

Single-cell transcriptome atlas of lung adenocarcinoma featured with ground glass nodules

As an early type of lung adenocarcinoma, ground glass nodule (GGN) has been detected increasingly and now accounts for most lung cancer outpatients. GGN has a satisfactory prognosis and its characteristics are quite different from solid adenocarcinoma (SADC). We compared the GGN adenocarcinoma (GGN-ADC) with SADC using the single-cell RNA sequencing (scRNA-seq) to fully understand GGNs. The tumor samples of five patients with lung GGN-ADCs and five with SADCs underwent surgery were digested to a single-cell suspension and analyzed using 10× Genomic scRNA-seq techniques. We obtained 60,459 cells and then classified them as eight cell types, including cancer cells, endothelial cells, fibroblasts, T cells, B cells, Nature killer cells, mast cells, and myeloid cells. We provided a comprehensive description of the cancer cells and stromal cells. We found that the signaling pathways related to cell proliferation were downregulated in GGN-ADC cancer cells, and stromal cells had different effects in GGN-ADC and SADC based on the analyses of scRNA-seq results. In GGN-ADC, the signaling pathways of angiogenesis were downregulated, fibroblasts expressed low levels of some collagens, and immune cells were more activated. Furthermore, we used flow cytometry to isolate the cancer cells and T cells in 12 GGN-ADC samples and in an equal number of SADC samples, including CD4+ T and CD8+ T cells, and validated the expression of key molecules by quantitative real-time polymerase chain reaction analyses. Through comprehensive analyses of cell phenotypes in GGNs, we provide deep insights into lung carcinogenesis that will be beneficial in lung cancer prevention and therapy.

Integrative stemness characteristics associated with prognosis and the immune microenvironment in esophageal cancer

BACKGROUND

Cancer stem cells (CSCs) induces tumor metastasis and recurrence. However, the role of CSCs in molding the tumor immune microenvironment (TIME) is largely inexplicit. This study aimed to comprehensively characterize the stemness of esophageal cancer (EC) and correlate the stemness patterns with TIME.

METHODS

A trained stemness index model was used to score EC patients based on the one-class logistic regression (OCLR) machine-learning algorithm. Gene expression-based stemness index (mRNAsi) and DNA methylation-based stemness index (mDNAsi) were calculated for integrative analyses of EC stemness in the training cohort (n = 182) and validation cohort (n = 179). Intrinsic stemness patterns were estimated to determine its association with clinical features, biological pathways, prognosis, and potential inhibitors. Additionally, the dynamic interplay between EC stemness and TIME was integrally characterized.

RESULTS

Analyses of EC stemness and clinical characteristics indicated that higher-stage and metastatic tumors featured more dedifferentiated phenotypically. Univariate and multivariate Cox regression analyses revealed that mRNAsi was significantly associated with overall survival (OS) of EC patients, whereas no relationship was observed between mDNAsi and OS. Notably, prolonged OS was observed with esophageal squamous cell carcinoma (ESCC) in low versus high mRNAsi groups, whereas the OS was equivalent between the two groups for esophageal adenocarcinoma (ESAD). The mRNAsi may thus recapitulate prognostic molecular subgroups of EC. The prognostic model comprising 14 stemness signatures was constructed using combined Cox and Lasso regression analyses which effectively distinguished individual survival of ESCC in two cohorts. Nevertheless, no significant differences in OS was observed when the same prognostic model of ESCC was applied to ESAD. Gene Set Enrichment Analysis (GSEA) of selected stemness signatures indicated that ESCC stemness is involved in immune-related pathways. Furthermore, ESCC stemness and stemness-related signatures were associated with tumor-infiltrating immune cells, immunoscore, and PD-L1 expression. Compounds specific to the selected stemness signatures were detected using the CMap database.

CONCLUSION

This study determined integrated characteristics of EC stemness. The identified mRNAsi-based signatures conferred with the predictive ability of personalized ESCC prognosis and highlighted the potential targets for CSC-mediated immunotherapy. Analyses of the interface between ESCC stemness and TIME may help in predicting the efficacy of CSC-specific immunotherapy and provide insight into combinatorial therapy by targeting ESCC stem cells and TIME.

Exosomes: key players in cancer and potential therapeutic strategy

Exosomes are extracellular vesicles secreted by most eukaryotic cells and participate in intercellular communication. The components of exosomes, including proteins, DNA, mRNA, microRNA, long noncoding RNA, circular RNA, etc., which play a crucial role in regulating tumor growth, metastasis, and angiogenesis in the process of cancer development, and can be used as a prognostic marker and/or grading basis for tumor patients. Hereby, we mainly summarized as followed: the role of exosome contents in cancer, focusing on proteins and noncoding RNA; the interaction between exosomes and tumor microenvironment; the mechanisms that epithelial-mesenchymal transition, invasion and migration of tumor affected by exosomes; and tumor suppression strategies based on exosomes. Finally, the application potential of exosomes in clinical tumor diagnosis and therapy is prospected, which providing theoretical supports for using exosomes to serve precise tumor treatment in the clinic.

Five-lncRNA signature in plasma exosomes serves as diagnostic biomarker for esophageal squamous cell carcinoma

Changes in expression of long non-coding RNAs (lncRNAs) in plasma exosomes can be useful for diagnosis of cancer patients. Here, we conducted a four-stage study to identify plasma exosome lncRNAs with diagnostic potential in esophageal squamous cell carcinoma (ESCC). First, plasma exosome lncRNA expression profiles were examined in ESCC patients, esophagitis patients, and healthy controls using RNA sequencing. Differentially expressed plasma exosome lncRNAs from the lncRNA expression profile were then evaluated by qRT-PCR in a large cohort of ESCC patients, esophagitis patients, and healthy controls. Expression levels of the lncRNAs NR_039819, NR_036133, NR_003353, ENST00000442416.1, and ENST00000416100.1 were significantly higher in exosomes from ESCC patients than non-cancer controls. We also confirmed that levels of these five plasma exosome lncRNAs decreased markedly in ESCC patients after surgery. Our results suggest that these five exosome lncRNAs may serve as highly effective, noninvasive biomarkers for ESCC diagnosis.

Comprehensive landscape of extracellular vesicle-derived RNAs in cancer initiation, progression, metastasis and cancer immunology

Extracellular vesicles (EVs), a class of heterogeneous membrane vesicles, are generally divided into exosomes and microvesicles on basis of their origination from the endosomal membrane or the plasma membrane, respectively. EV-mediated bidirectional communication among various cell types supports cancer cell growth and metastasis. EVs derived from different cell types and status have been shown to have distinct RNA profiles, comprising messenger RNAs and non-coding RNAs (ncRNAs). Recently, ncRNAs have attracted great interests in the field of EV-RNA research, and growing numbers of ncRNAs ranging from microRNAs to long ncRNAs have been investigated to reveal their specific functions and underlying mechanisms in the tumor microenvironment and premetastatic niches. Emerging evidence has indicated that EV-RNAs are essential functional cargoes in modulating hallmarks of cancers and in reciprocal crosstalk within tumor cells and between tumor and stromal cells over short and long distance, thereby regulating the initiation, development and progression of cancers. In this review, we discuss current findings regarding EV biogenesis, release and interaction with target cells as well as EV-RNA sorting, and highlight biological roles and molecular mechanisms of EV-ncRNAs in cancer biology.

Tumor-Secreted Exosomal lncRNA POU3F3 Promotes Cisplatin Resistance in ESCC by Inducing Fibroblast Differentiation into CAFs

Cancer-associated fibroblasts (CAFs), an activated subpopulation of fibroblasts, occupy a central position in the tumor microenvironment and have been shown to promote chemoresistance in multiple cancer types by secreting inflammatory cytokines. Herein, we report that tumor-secreted exosomal long non-coding RNAs (lncRNAs) can regulate cisplatin resistance in esophageal squamous cell carcinoma (ESCC) through transformation of normal fibroblasts (NFs) to CAFs. Primary CAFs and matched NFs were isolated from tumor tissues and matched normal esophageal epithelial tissues of ESCC patients. Fluorescence microscopy and qRT-PCR were used to investigate the transportation of exosomal lncRNAs from ESCC cells to NFs. To identify the specific lncRNAs involved, 14 ESCC-related lncRNAs were measured in NFs after incubation with exosomes from ESCC cells. We demonstrated that lncRNA POU3F3 can be transferred from ESCC cells to NFs via exosomes and that it mediated fibroblast activation. Activated fibroblasts further promoted proliferation and cisplatin resistance of ESCC cells through secreting interleukin 6 (IL-6). Moreover, our clinical data showed that high levels of plasma exosomal lncRNA POU3F3 correlated significantly with lack of complete response and poor survival in ESCC patients. Therefore, these data demonstrate that lncRNA POU3F3 is involved in cisplatin resistance in ESCC and that this effect is mediated through exosomal lncRNA POU3F3-induced transformation of NFs to CAFs.

Tumor-Derived EV-Encapsulated miR-181b-5p Induces Angiogenesis to Foster Tumorigenesis and Metastasis of ESCC

Pathological angiogenesis is necessary for tumor development and metastasis. Tumor-derived extracellular vesicles (EVs) play an important role in mediating the crosstalk between cancer cells and vascular endothelial cells. To date, whether and how microRNAs (miRNAs) encapsulated in tumor-derived EVs affect angiogenesis in esophageal squamous cell carcinoma (ESCC) remains unclear. Here, we showed that miR-181b-5p, an angiogenesis-promoting miRNA of ESCC, can be transferred from ESCC cells to vascular endothelial cells via EVs. In addition, ESCC-derived EVs-miR-181b-5p dramatically induced angiogenesis by targeting PTEN and PHLPP2, and thereby facilitated tumor growth and metastasis. Moreover, miR-181b-5p was highly expressed in ESCC tissues and serum EVs. High miR-181b-5p expression level in ESCC patients was well predicted for poor overall survival. Our work suggests that intercellular crosstalk between tumor cells and vascular endothelial cells is mediated by tumor-derived EVs. miR-181b-5p-enriched EVs secreted from ESCC cells are involved in angiogenesis that control metastasis of ESCC, providing a potential diagnostic biomarker or drug target for ESCC patients.

Long non-coding RNAs regulate drug resistance in cancer

Chemoresistance, whether intrinsic or acquired, is a major obstacle in the treatment of cancer. The resistance of cancer cells to chemotherapeutic drugs can result from various mechanisms. Over the last decade, it has been reported that 1ong noncoding RNAs (lncRNAs) can mediate carcinogenesis and drug resistance/sensitivity in cancer cells. This article reviews, in detail, recent studies regarding the roles of lncRNAs in mediating drug resistance.

Long non-coding RNAs regulate drug resistance in cancer

Chemoresistance, whether intrinsic or acquired, is a major obstacle in the treatment of cancer. The resistance of cancer cells to chemotherapeutic drugs can result from various mechanisms. Over the last decade, it has been reported that 1ong noncoding RNAs (lncRNAs) can mediate carcinogenesis and drug resistance/sensitivity in cancer cells. This article reviews, in detail, recent studies regarding the roles of lncRNAs in mediating drug resistance.

OLR1 Promotes Pancreatic Cancer Metastasis via Increased c-Myc Expression and Transcription of HMGA2

Pancreatic cancer is one of the most lethal human malignancies, partly because of its propensity for metastasis. However, the mechanisms of metastasis in pancreatic cancer remain unclear. Oxidized low-density lipoprotein receptor 1 (OLR1), a lectin-like scavenger receptor that recognizes several ligands, such as oxidized low-density lipoprotein, was previously reported in cardiovascular and metabolic diseases. The role and mechanism of OLR1 in pancreatic cancer is unclear. In this study, we found that OLR1 expression was significantly higher in pancreatic cancer tissues than that in adjacent normal tissues and closely associated with reduced overall survival. OLR1 promoted proliferation and metastasis of pancreatic cancer cells in vitro and in vivo. Mechanistically, OLR1 increased HMGA2 transcription by upregulating c-Myc expression to promote the metastasis of pancreatic cancer cells. In addition, patients with pancreatic cancer with high expression of OLR1-c-Myc-HMGA2 axis showed worse prognosis compared with patients with low expression of OLR1-c-Myc-HMGA2 axis. IMPLICATIONS: Our findings suggested that the OLR1-c-Myc-HMGA2 axis promotes metastasis of pancreatic cancer cells and may serve as potential therapeutic targets and prognosis markers for patients with pancreatic cancer.

Identification of a nomogram based on long non-coding RNA to improve prognosis prediction of esophageal squamous cell carcinoma

PURPOSE

Esophageal squamous cell carcinoma (ESCC) remains a common aggressive malignancy in the world. Several long non-coding RNAs (lncRNAs) are reported to predict the prognosis of ESCC. Therefore, an in-depth research is urgently needed to further investigate the prognostic value of lncRNAs in ESCC.

RESULTS

From the training set, we identified a eight-lncRNA signature (including AP000487, AC011997, LINC01592, LINC01497, LINC01711, FENDRR, AC087045, AC137770) which separated the patients into two groups with significantly different overall survival (hazard ratio, HR = 3.79, 95% confidence interval, 95% CI [2.56-5.62]; P < 0.001). The signature was applied to the validation set (HR = 2.73, 95%CI [1.65-4.53]; P < 0.001) and showed similar prognostic values. Stratified, univariate and multivariate Cox regression analysis indicated that the signature was an independent prognostic factor for patients with ESCC. A nomogram based on the lncRNAs signature, age, grade and stage was developed and showed good accuracy for predicting 1-, 3- and 5-year survival probability of ESCC patients. We found a strong correlation between the gene significance for the survival time and T stage. Eight modules were constructed, among which the key module most closely associated with clinical information was identified.

CONCLUSIONS

Our eight-lincRNA signature and nomogram could be practical and reliable prognostic tools for esophageal squamous cell carcinoma.

METHODS

We downloaded the lncRNA expression profiles of ESCC patients from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) datasets and separated to training and validation cohort. The univariate, least absolute shrinkage and selection operator (LASSO) and multivariate Cox regression analysis were used to identify a lncRNA-based signature. The predictive value of the signature was assessed using the Kaplan-Meier method, receiver operating characteristic (ROC) curves and area under curve (AUC). Weighted gene co-expression network analysis (WGCNA) was applied to predict the intrinsic relationship between gene expressions. In addition, we further explored the combination of clinical information and module construction.

Emerging Role of Non-Coding RNAs in Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is a highly prevalent tumor and is associated with ethnicity, genetics, and dietary intake. Non-coding RNAs (ncRNAs), specifically microRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs) have been reported as functional regulatory molecules involved in the development of many human cancers, including ESCC. Recently, several ncRNAs have been detected as oncogenes or tumor suppressors in ESCC progression. These ncRNAs influence the expression of specific genes or their associated signaling pathways. Moreover, interactions of ncRNAs are evident in ESCC, as miRNAs regulate the expression of lncRNAs, and further, lncRNAs and circRNAs function as miRNA sponges to compete with the endogenous RNAs. Here, we discuss and summarize the findings of recent investigations into the role of ncRNAs (miRNAs, lncRNAs, and circRNAs) in the development and progression of ESCC and how their interactions regulate ESCC development.

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.

LINC00511 contributes to glioblastoma tumorigenesis and epithelial-mesenchymal transition via LINC00511/miR-524-5p/YB1/ZEB1 positive feedback loop

Tumour invasion is closely related to the prognosis and recurrence of glioblastoma multiforme and partially attributes to epithelial‐mesenchymal transition. Long intergenic non‐coding RNA 00511 (LINC00511) plays a pivotal role in tumour; however, the role of LINC00511 in GBM, especially in the epigenetic molecular regulation mechanism of EMT, is still unclear. Here, we found that LINC00511 was up‐regulated in GBM tissues and relatively high LINC00511 expression predicted poorer prognosis. Moreover, ectopic LINC00511 enhanced GBM cells proliferation, EMT, migration and invasion, whereas LINC00511 knockdown had the opposite effects. Mechanistically, we confirmed that ZEB1 acted as a transcription factor for LINC00511 in GBM cells. Subsequently, we found that LINC00511 served as a competing endogenous RNA that sponged miR‐524‐5p to indirectly regulate YB1, whereas, up‐regulated YB1 promoted ZEB1 expression, which inversely facilitated LINC00511 expression. Finally, orthotopic xenograft models were performed to further demonstrate the LINC00511 on GBM tumorigenesis. This study demonstrates that a LINC00511/miR‐524‐5p/YB1/ZEB1 positive feedback loop provides potential therapeutic targets for GBM progression.

LncRNA KLF3-AS1 in human mesenchymal stem cell-derived exosomes ameliorates pyroptosis of cardiomyocytes and myocardial infarction through miR-138-5p/Sirt1 axis

AIM

Myocardial infarction (MI) is a severe disease with increased mortality and disability rates, posing heavy economic burden for society. Exosomes were uncovered to mediate intercellular communication after MI. This study aims to explore the effect and mechanism of lncRNA KLF3-AS1 in exosomes secreted by human mesenchymal stem cells (hMSCs) on pyroptosis of cardiomyocytes and MI.

METHODS

Exosomes from hMSCs were isolated and identified. Exosomes from hMSCs with transfection of KLF3-AS1 for overexpression were injected into MI rat model or incubated with hypoxia cardiomyocytes. Effect of KLF3-AS1 on MI area, cell viability, apoptosis, and pyroptosis was determined. The relationship among miR-138-5p, KLF3-AS1, and Sirt1 was verified by dual-luciferase reporter assay. Normal cardiomyocytes were transfected with miR-138-5p inhibitor or sh-Sirt1 to clarify whether alteration of miR-138-5p or sh-Sirt1 can regulate the effect of KLF3-AS1 on cardiomyocytes.

RESULTS

Exosomes from hMSCs were successfully extracted. Transfection of KLF3-AS1 exosome in rats and incubation with KLF3-AS1 exosome in hypoxia cardiomyocytes both verified that overexpression of KLF3-AS1 in exosomes leads to reduced MI area, decreased cell apoptosis and pyroptosis, and attenuated MI progression. KLF3-AS1 can sponge miR-138-5p to regulate Sirt1 expression. miR-138-5p inhibitor transfection and KLF3-AS1 exosome incubation contribute to attenuated pyroptosis and MI both in vivo and in vitro, while transfection of sh-Sirt1 could reverse the protective effect of exosomal KLF3-AS1 on hypoxia cardiomyocytes.

CONCLUSION

LncRNA KLF3-AS1 in exosomes secreted from hMSCs by acting as a ceRNA to sponge miR-138-5p can regulate Sirt1 so as to inhibit cell pyroptosis and attenuate MI progression.

Extracellular vesicles as a novel source of biomarkers in liquid biopsies for monitoring cancer progression and drug resistance

Cancer-derived extracellular vesicles (EVs) have been detected in the bloodstream and other biofluids of cancer patients. They carry various tumor-derived molecules such as mutated DNA and RNA fragments, oncoproteins as well as miRNA and protein signatures associated with various phenotypes. The molecular cargo of EVs partially reflects the intracellular status of their cellular origin, however various sorting mechanisms lead to the enrichment or depletion of EVs in specific nucleic acids, proteins or lipids. It is becoming increasingly clear that cancer-derived EVs act in a paracrine and systemic manner to promote cancer progression by transferring aggressive phenotypic traits and drug-resistant phenotypes to other cancer cells, modulating the anti-tumor immune response, as well as contributing to remodeling the tumor microenvironment and formation of pre-metastatic niches. These findings have raised the idea that cancer-derived EVs may serve as analytes in liquid biopsies for real-time monitoring of tumor burden and drug resistance. In this review, we have summarized recent longitudinal clinical studies describing promising EV-associated biomarkers for cancer progression and tracking cancer evolution as well as pre-clinical and clinical evidence on the relevance of EVs for monitoring the emergence or progression of drug resistance. Furthermore, we outlined the state-of-the-art in the development and commercialization of EV-based biomarkers and discussed the scientific and technological challenges that need to be met in order to translate EV research into clinically applicable tools for precision medicine.

Hypoxic exosomes facilitate angiogenesis and metastasis in esophageal squamous cell carcinoma through altering the phenotype and transcriptome of endothelial cells

Background

In cancer progression, hypoxia, or low oxygen tension, is a major regulator of tumor aggressiveness and metastasis. However, how cancer cells adapt to the hypoxia and communicate with other mesenchymal cells in microenvironment during tumor development remains to be elucidated. Here, we investigated the involvement of exosomes in modulating angiogenesis and enhancing metastasis in esophageal squamous cell carcinoma (ESCC).

Methods

Differential centrifugation, transmission electron microscopy and nanoparticle tracking analysis were used to isolate and characterize exosomes. Colony formation and transwell assay were performed to assess the proliferation, migration and invasion of human umbilical vein endothelial cells (HUVECs). The tube formation assay and matrigel plug assay were used to evaluate the vascular formation ability of HUVECs in vitro and in vivo respectively. An in vivo nude mice model was established to detect the regulatory role of exosomes in ESCC progression. Microarray analysis was performed to analyze the transcriptome profiles in HUVECs.

Results

Exosomes derived from ESCC cells cultured under hypoxia played a better role in promoting proliferation, migration, invasion and tube formation of HUVECs in vitro and in vivo than exosomes from ESCC cells cultured under normoxia. Moreover, hypoxic exosomes significantly enhanced the tumor growth and lung metastasis compared with normoxic exosomes in nude mice models. Interestingly, endothelial cells were programmed by hypoxic and normoxic exosomes from ESCC cells which altered the transcriptome profile of HUVECs.

Conclusions

Taken together, our data identified an angiogenic role of exosomes from ESCC cells which shed light on the further application of exosomes as valuable therapeutic target for ESCC.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1384-8) contains supplementary material, which is available to authorized users.