Gastric cancer-derived exosomes promote peritoneal metastasis by destroying the mesothelial barrier

Au Nanorings/TiO2 NPs@MXene-Based Metasurfaces with a Magnetic Mirror-Modulated ECL Strategy for Extracellular Vesicle Detection

A metasurface as an artificial electromagnetic structure can concentrate optical energy into nanometric volumes to strongly enhance the light-matter interaction, which has been becoming a powerful platform for optical sensing, nonlinear effects, and quantum optics. Herein, we developed a novel hybrid plasmonic-dielectric metasurface consisting of Au nanorings (Au NRs) and TiO2 nanoparticles derived from MXene (TiO2 NPs@MXene). The hybrid metasurface simultaneously benefited from the high near-field enhancement effect of plasmonic materials and the low loss of dielectric materials. Furthermore, the optical modulation efficiency of the hybrid metasurface can be regulated by a magnetic mirror configuration. The magnetic mirror acted like a mirror, confining the electrons to a limited region and increasing the density of the surface plasmon. Moreover, the electrochemiluminescence (ECL) of the Cu2BDC metal-organic framework (Cu2BDC-MOF) served as a light source for the Au NRs/TiO2 NPs@MXene metasurface. Due to the exceptional light manipulation capability of the hybrid metasurface and the coordination of the magnetic mirror, the isotropic ECL signal can be dynamically amplified and converted into polarized emission. Finally, a metasurface-regulated ECL (MECL)-based biosensor with a dual-positive membrane protein recognition strategy was developed for the accurate identification of gastric cancer-derived extracellular vesicles. The novel MECL research opened up a new route in the realization of dynamically tunable metasurfaces for optical sensing and novel nanophotonic devices.

Circulating Exosomal MicroRNA Signature Predicts Peritoneal Metastasis in Patients with Advanced Gastric Cancer

BACKGROUND

Despite a radical operation, about half of gastric cancer (GC) patients with advanced GC experience peritoneal metastasis (PM), and the patients with PM have a poor prognosis. However, because staging laparoscopy was a highly invasive procedure for patients, identification of PM using a liquid biopsy can be useful for patients with GC.

METHODS

This study analyzed two genome-wide miRNA expression profiling datasets (GSE164174 and TCGA). The study prioritized biomarkers in pretreatment plasma specimens from clinical training and validation cohorts of patients with GC. The authors developed an integrated exosomal miRNA panel and established a risk-stratification model, which was combined with the miRNA panel and currently used tumor markers (CEA, CA19-9, CA125, and CA72-4 levels).

RESULTS

The comprehensive discovery effort identified a four-miRNA panel that robustly predicted the metastasis with excellent accuracy in the TCGA dataset (area under the curve [AUC] 0.86). A circulating exosomal miRNA panel was established successfully with remarkable diagnostic accuracy in the clinical training (AUC 0.85) and validation (AUC 0.86) cohorts. Moreover, the predictive accuracy of the panel was significantly superior to that of conventional clinical factors (P < 0.01), and the risk-stratification model was dramatically superior to the panel and currently used clinical factors for predicting PM (AUC 0.94; univariate: odds ratio [OR] 77.00 [P < 0.01]; multivariate OR 57.71 [P = 0.01]).

CONCLUSIONS

The novel risk-stratification model for predicting PM has potential for clinical translation as a liquid biopsy assay for patients with GC. The study findings highlight the potential clinical impact of the model for improved selection and management of patients with GC.

Cancer-Associated Fibroblasts in Intrahepatic Cholangiocarcinoma: Insights into Origins, Heterogeneity, Lymphangiogenesis, and Peritoneal Metastasis

Intrahepatic cholangiocarcinoma (iCCA) denotes a rare, highly malignant, and heterogeneous class of primary liver adenocarcinomas exhibiting phenotypic characteristics of cholangiocyte differentiation. Among the distinctive pathological features of iCCA, one that differentiates the most common macroscopic subtype (eg, mass-forming type) of this hepatic tumor from conventional hepatocellular carcinoma, is a prominent desmoplastic reaction manifested as a dense fibro-collagenous-enriched tumor stroma. Cancer-associated fibroblasts (CAFs) represent the most abundant mesenchymal cell type in the desmoplastic reaction. Although the protumor effects of CAFs in iCCA have been increasingly recognized, more recent cell lineage tracing studies, advanced single-cell RNA sequencing, and expanded biomarker analyses have provided new awareness into their ontogeny, as well as underscored their biological complexity as reflected by the presence of multiple subtypes. In addition, evidence has been described to support CAFs' potential to display cancer-restrictive roles, including immunosuppression. However, CAFs also play important roles in facilitating metastasis, as exemplified by lymph node metastasis and peritoneal carcinomatosis, which are common in iCCA. Herein, the authors provide a timely appraisal of the origins and phenotypic and functional complexity of CAFs in iCCA, together with providing mechanistic insights into lymphangiogenesis and peritoneal metastasis relevant to this lethal human cancer.

Mesenchymal stem cell-derived exosomes: Characteristics and applications in disease pathology and management

Mesenchymal stem cells (MSCs) possess a role in tissue regeneration and homeostasis because of inherent immunomodulatory capacity and the production of factors that encourage healing. There is substantial evidence that MSCs' therapeutic efficacy is primarily determined by their paracrine function including in cancers. Extracellular vesicles (EVs) are basic paracrine effectors of MSCs that reside in numerous bodily fluids and cell homogenates and play an important role in bidirectional communication. MSC-derived EVs (MSC-EVs) offer a wide range of potential therapeutic uses that exceed cell treatment, while maintaining protocell function and having less immunogenicity. We describe characteristics and isolation methods of MSC-EVs, and focus on their therapeutic potential describing its roles in tissue repair, anti-fibrosis, and cancer with an emphasis on the molecular mechanism and immune modulation and clinical trials. We also explain current understanding and challenges in the clinical applications of MSC-EVs as a cell free therapy.

Roles and application of exosomes in the development, diagnosis and treatment of gastric cancer

As important messengers of intercellular communication, exosomes can regulate local and distant cellular communication by transporting specific exosomal contents and can also promote or suppress the development and progression of gastric cancer (GC) by regulating the growth and proliferation of tumor cells, the tumor-related immune response and tumor angiogenesis. Exosomes transport bioactive molecules including DNA, proteins, and RNA (coding and noncoding) from donor cells to recipient cells, causing reprogramming of the target cells. In this review, we will describe how exosomes regulate the cellular immune response, tumor angiogenesis, proliferation and metastasis of GC cells, and the role and mechanism of exosome-based therapy in human cancer. We will also discuss the potential application value of exosomes as biomarkers in the diagnosis and treatment of GC and their relationship with drug resistance.

The role of extracellular vesicles from placenta and endometrium in pregnancy: Insights from tumor biology

Extracellular vesicles (EVs) are small membrane-bound particles secreted by various cell types that play a critical role in intercellular communication by packaging and delivering biomolecules. In recent years, EVs have emerged as essential messengers in mediating physiological and pathological processes in tumor biology. The tumor microenvironment (TME) plays a pivotal role in tumor generation, progression, and metastasis. In this review, we provide an overview of the impact of tumor-derived EVs on both tumor cells and the TME. Moreover, we draw parallels between tumor biology and pregnancy, as successful embryo implantation also requires intricate intercellular communication between the placental trophecepiblast and the endometrial epithelium. Additionally, we discuss the involvement of EVs in targeting immune responses, trophoblast invasion, migration, and angiogenesis, which are shared biological processes between tumors and pregnancy. Specifically, we highlight the effects of placenta-derived EVs on the fetal-maternal interface, placenta, endometrium, and maternal system, as well as the role of endometrium-derived EVs in embryo-endometrial communication. However, challenges still exist in EVs research, including the standardization of EVs isolation methods for diagnostic testing, which also apply to reproductive systems where EVs-mediated communication is proposed to take place. Through this review, we aim to deepen the understanding of EVs, particularly in the context of reproductive biology, and encourage further investigation in this field.

Plasmonic nanocavity-modulated electrochemiluminescence sensor for gastric cancer exosomal miRNA detection

Plasmonic nanocavity possessing highly light field confinement and electromagnetic field enhancement can concentrate and enhance the luminescence signal. The plasmonic nanocavity has the great potential value in biosensing research and improve analytical sensitivity. In this work, we constructed a plasmonic nanocavity between circular Au nanoplate-film and spherical Au nanoparticle with tetrahedral DNA nanostructures. The nanocavity structure can regulate the local density of optical states and provide the field restriction to enhance the spontaneous ECL radiation of PEDOT-S dots. Additionally, Au nanoparticle acted as nanoantenna which localized and modulated ECL to directional emission. Because the plasmonic nanocavity effectively collected and redistributed ECL signal, the emission was enhanced by 5.9 times with polarized characteristics. The proposed plasmonic nanocavity-based ECL sensor was further used to detect exosomal miRNA-223-3p in ascites. The detection results indicated the novel sensing strategy can assist early diagnosis of peritoneal metastasis of gastric cancer.

The biological role of extracellular vesicles in gastric cancer metastasis

Gastric cancer (GC) is a tumor characterized by high incidence and mortality, with metastasis being the primary cause of poor prognosis. Extracellular vesicles (EVs) are an important intercellular communication medium. They contain bioactive substances such as proteins, nucleic acids, and lipids. EVs play a crucial biological role in the process of GC metastasis. Through mechanisms such as remodeling the tumor microenvironment (TME), immune suppression, promoting angiogenesis, and facilitating epithelial-mesenchymal transition (EMT) and mesothelial-mesenchymal transition (MMT), EVs promote invasion and metastasis in GC. Further exploration of the biological roles of EVs will contribute to our understanding of the mechanisms underlying GC metastasis and may provide novel targets and strategies for the diagnosis and treatment of GC. In this review, we summarize the mechanisms by which EVs influence GC metastasis from four aspects: remodeling the TME, modulating the immune system, influencing angiogenesis, and modulating the processes of EMT and MMT. Finally, we briefly summarized the organotropism of GC metastasis as well as the potential and limitations of EVs in GC.

Exosomes secreted by ST3GAL5high cancer cells promote peritoneal dissemination by establishing a premetastatic microenvironment

Peritoneal dissemination of cancer affects patient survival. The behavior of peritoneal mesothelial cells (PMCs) and immune cells influences the establishment of a microenvironment that promotes cancer cell metastasis in the peritoneum. Here, we investigated the roles of lactosylceramide alpha-2,3-sialyltransferase (ST3G5; also known as ST3GAL5 and GM3 synthase) in the exosome-mediated premetastatic niche in peritoneal milky spots (MSs). Exosomes secreted from ST3G5high cancer cells (ST3G5high -cExos) were found to contain high levels of hypoxia-inducible factor 1-alpha (HIF1α) and accumulated in MSs via uptake in macrophages (MΦs) owing to increased expression of sialic acid-binding Ig-like lectin 1 (CD169; also known as SIGLEC1). ST3G5high -cExos induced pro-inflammatory cytokines and glucose metabolic changes in MΦs, and the interaction of these MΦs with PMCs promoted mesothelial-mesenchymal transition (MMT) in PMCs, thereby generating αSMA+ myofibroblasts. ST3G5high -cExos also increased the expression of immune checkpoint molecules and T-cell exhaustion in MSs, which accelerated metastasis to the omentum. These events were prevented following ST3G5 depletion in cancer cells. Mechanistically, ST3G5high -cExos upregulated chemokines, including CC-chemokine ligand 5 (CCL5), in recipient MΦs and dendritic cells (DCs), which induced MMT and immunosuppression via activation of signal transducer and activator of transcription 3 (STAT3). Maraviroc, a C-C chemokine receptor type 5 (CCR5) antagonist, prevented ST3G5high -cExo-mediated MMT, T-cell suppression, and metastasis in MSs. Our results suggest ST3G5 as a suitable therapeutic target for preventing cExo-mediated peritoneal dissemination.

TRAIL-dependent apoptosis of peritoneal mesothelial cells by NK cells promotes ovarian cancer invasion

A crucial requirement for metastasis formation in ovarian high-grade serous carcinoma (HGSC) is the disruption of the protective peritoneal mesothelium. Using co-culture systems of primary human cells, we discovered that tumor-associated NK cells induce TRAIL-dependent apoptosis in mesothelial cells via death receptors DR4 and DR5 upon encounter with activated T cells. Upregulation of TRAIL expression in NK cells concomitant with enhanced cytotoxicity toward mesothelial cells was driven predominantly by T-cell-derived TNFα, as shown by affinity proteomics-based analysis of the T cell secretome in conjunction with functional studies. Consistent with these findings, we detected apoptotic mesothelial cells in the peritoneal fluid of HGSC patients. In contrast to mesothelial cells, HGSC cells express negligible levels of both DR4 and DR5 and are TRAIL resistant, indicating cell-type-selective killing by NK cells. Our data point to a cooperative action of T and NK in breaching the mesothelial barrier in HGSC patients.

Targeting carcinoma-associated mesothelial cells with antibody-drug conjugates in ovarian carcinomatosis

Ovarian carcinomatosis is characterized by the accumulation of carcinoma-associated mesothelial cells (CAMs) in the peritoneal stroma and mainly originates through a mesothelial-to-mesenchymal transition (MMT) process. MMT has been proposed as a therapeutic target for peritoneal metastasis. Most ovarian cancer (OC) patients present at diagnosis with peritoneal seeding, which makes tumor progression control difficult by MMT modulation. An alternative approach is to use antibody-drug conjugates (ADCs) targeted directly to attack CAMs. This strategy could represent the cornerstone of precision-based medicine for peritoneal carcinomatosis. Here, we performed complete transcriptome analyses of ascitic fluid-isolated CAMs in advanced OC patients with primary-, high-, and low-grade, serous subtypes and following neoadjuvant chemotherapy. Our findings suggest that both cancer biological aggressiveness and chemotherapy-induced tumor mass reduction reflect the MMT-associated changes that take place in the tumor surrounding microenvironment. Accordingly, MMT-related genes, including fibroblast activation protein (FAP), mannose receptor C type 2 (MRC2), interleukin-11 receptor alpha (IL11RA), myristoylated alanine-rich C-kinase substrate (MARCKS), and sulfatase-1 (SULF1), were identified as specific actionable targets in CAMs of OC patients, which is a crucial step in the de novo design of ADCs. These cell surface target receptors were also validated in peritoneal CAMs of colorectal cancer peritoneal implants, indicating that ADC-based treatment could extend to other abdominal tumors that show peritoneal colonization. As proof of concept, a FAP-targeted ADC reduced tumor growth in an OC xenograft mouse model with peritoneal metastasis-associated fibroblasts. In summary, we propose MMT as a potential source of ADC-based therapeutic targets for peritoneal carcinomatosis. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Downregulation of cancer-associated fibroblast exosome-derived miR-29b-1-5p restrains vasculogenic mimicry and apoptosis while accelerating migration and invasion of gastric cancer cells via immunoglobulin domain-containing 1/zonula occluden-1 axis

Background: Cancer-associated fibroblast (CAF) exosomal miRNAs have gradually a hot spot in cancer therapy. This study mainly explores the effect of CAF-derived exosomal miR-29b-1-5p on gastric cancer (GC) cells.Methods: CAFs and exosomes were identified by Western blot and transmission electron microscopy. CAF-derived exosomes-GC cells co-culture systems were constructed. Effects of CAF-derived exosomal miR-29b-1-5p on GC cells were determined by cell counting kit-8, flow cytometry, wound healing, Transwell assays and Western blot. The relationship between miR-29b-1-5p and immunoglobulin domain-containing 1 (VSIG1) was assessed by TargetScan, dual-luciferase reporter and RNA immunoprecipitation (RIP) experiments. The interaction between VSIG1 and zonula occluden-1 (ZO-1) was detected by co-immunoprecipitation. Expressions of miR-29b-1-5p, VSIG1 and ZO-1 were determined by quantitative real-time PCR. Vascular mimicry (VM) was detected using immunohistochemistry and tube formation assays. Rescue experiments and xenograft tumor assays were used to further determine the effect of CAF-derived exosomal miR-29b-1-5p/VSIG1 on GC.Results: VM structure, upregulation of miR-29b-1-5p, and downregulation of VSIG1 and ZO-1 were shown in GC tissues. MiR-29b-1-5p targeted VSIG1, which interacted with ZO-1. CAF-derived exosomal miR-29b-1-5p inhibitor suppressed the viability, migration, invasion and VM formation, but promoted the apoptosis of GC cells. MiR-29b-1-5p inhibitor increased levels of VSIG1, ZO-1 and E-cadherin, whilst decreasing levels of VE-cadherin, N-cadherin and Vimentin in vitro and in vivo, which however was partially reversed by shVSIG1. Downregulation of CAF-derived exosomal miR-29b-1-5p impeded GC tumorigenesis and VM structure in vivo by upregulating VSIG1/ZO-1 expression.Conclusion: Downregulation of CAF-derived exosomal miR-29b-1-5p inhibits GC progression via VSIG1/ZO-1 axis.

Effects of Hyperthermia and Hyperthermic Intraperitoneal Chemoperfusion on the Peritoneal and Tumor Immune Contexture

Hyperthermia combined with intraperitoneal (IP) drug delivery is increasingly used in the treatment of peritoneal metastases (PM). Hyperthermia enhances tumor perfusion and increases drug penetration after IP delivery. The peritoneum is increasingly recognized as an immune-privileged organ with its own distinct immune microenvironment. Here, we review the immune landscape of the healthy peritoneal cavity and immune contexture of peritoneal metastases. Next, we review the potential benefits and unwanted tumor-promoting effects of hyperthermia and the associated heat shock response on the tumor immune microenvironment. We highlight the potential modulating effect of hyperthermia on the biomechanical properties of tumor tissue and the consequences for immune cell infiltration. Data from translational and clinical studies are reviewed. We conclude that (mild) hyperthermia and HIPEC have the potential to enhance antitumor immunity, but detailed further studies are required to distinguish beneficial from tumor-promoting effects.

Intermittent hypoxia BMSCs-derived exosomal miR-31-5p promotes lung adenocarcinoma development via WDR5-induced epithelial mesenchymal transition

BACKGROUND

Intermittent hypoxia (IH) is a factor involved in the incidence and progression of lung adenocarcinoma (LUAD). Bone marrow-derived bone mesenchymal stem cells (BMSCs)-derived exosomes are related to the promotion of tumor development. The objective of this experiment was to clarify the mechanism of exosomes from BMSCs in promoting the progression of LUAD induced by IH.

METHODS

This study examined if IH BMSCS-derived exosomes affect the malignancy of LUAD cells in vitro. Dual-luciferase assays were conducted to confirm the target of miR-31-5p with WD repeat domain 5 (WDR5). We further investigated whether or not  exosomal miR-31-5p or WDR5 could regulate epithelial-mesenchymal transition (EMT). We determined the effect of IH exosomes using a tumorigenesis model in vivo.

RESULTS

miR-31-5p entered into LUAD cells via exosomes. MiR-31-5p was greatly upregulated in IH BMSCs-derived exosomes compared with RA exosomes. Increased expression of exosomal miR-31-5p induced by IH was discovered to target WDR5 directly, increased activation of WDR5, and significantly facilitated EMT, thereby promoting LUAD progression.

CONCLUSIONS

The promoting effect of IH on LUAD is achieved partly through BMSCs-derived exosomal miR-31-5p triggering WDR5 and promoting EMT.

Prognostic Significance of PD-L1 Expression in Gastric Cancer Patients with Peritoneal Metastasis

BACKGROUND

Recently, many studies have explored the relationship between the expression of programmed death ligand 1 (PD-L1) and prognosis in gastric cancer, but there is still controversy. Additionally, few studies have specifically investigated the expression of PD-L1 in patients with peritoneal metastasis.

METHODS

Immunohistochemistry was used to analyze the expression of PD-L1 in gastric cancer patients with peritoneal metastasis. The combined positive score (CPS) was calculated to evaluate the expression of PD-L1, and the clinicopathological data were analyzed to explore prognostic significance.

RESULTS

In total, 147 gastric cancer patients with peritoneal metastasis were enrolled. The negative PD-L1 expression was defined as a CPS < 1, and high PD-L1 expression was defined as a CPS ≥ 10. PD-L1 expression with CPS ≥ 1 and CPS-negative was detected in 67 (45.58%) and 80 (54.42%) patients, respectively. High PD-L1 expression at PD-L1 CPS ≥ 10 was detected in 21(14.29%) patients. The median overall survival (OS) was 18.53 months in the CPS < 10 group and 27.00 months in the CPS ≥ 10 group; the OS difference between the two groups was significant (p = 0.015). Multivariate analysis demonstrated that a poor Eastern Cooperative Oncology Group performance score (ECOG PS) (p = 0.002) and severe peritoneal metastasis (p = 0.033) were significantly associated with poor survival, while palliative chemotherapy (p = 0.002) and high PD-L1 expression (p = 0.008) were independent and significantly favorable prognostic factors.

CONCLUSIONS

Our study demonstrated that PD-L1 expression was widely presented in gastric cancer patients with peritoneal metastasis, while a CPS no less than 10 predicted better prognosis.

Intraperitoneal transfer of microRNA-29b-containing small extracellular vesicles can suppress peritoneal metastases of gastric cancer

Small extracellular vesicles (sEV) contain various microRNAs (miRNAs) and play crucial roles in the tumor metastatic process. Although miR-29b levels in peritoneal exosomes were markedly reduced in patients with peritoneal metastases (PM), their role has not been fully clarified. In this study, we asked whether the replacement of miR-29b can affect the development of PM in a murine model. UE6E7T-12, human bone marrow-derived mesenchymal stem cells (BMSCs), were transfected with miR-29b-integrating recombinant lentiviral vector and sEV were isolated from culture supernatants using ultracentrifugation. The sEV contained markedly increased amounts of miR-29b compared with negative controls. Treatment with transforming growth factor-β1 decreased the expression of E-cadherin and calretinin with increased expression of vimentin and fibronectin on human omental tissue-derived mesothelial cells (HPMCs). However, the effects were totally abrogated by adding miR-29b-rich sEV. The sEV inhibited proliferation and migration of HPMCs by 15% (p < 0.005, n = 6) and 70% (p < 0.005, n = 6), respectively, and inhibited adhesion of NUGC-4 and MKN45 to HPMCs by 90% (p < 0.0001, n = 5) and 77% (p < 0.0001, n = 5), respectively. MicroRNA-29b-rich murine sEV were similarly obtained using mouse BMSCs and examined for in vivo effects with a syngeneic murine model using YTN16P, a highly metastatic clone of gastric cancer cell. Intraperitoneal (IP) transfer of the sEV every 3 days markedly reduced the number of PM from YTN16P in the mesentery (p < 0.05, n = 6) and the omentum (p < 0.05, n = 6). Bone marrow mesenchymal stem cell-derived sEV are a useful carrier for IP administration of miR-29b, which can suppress the development of PM of gastric cancer.

Localized chemotherapy approaches and advanced drug delivery strategies: a step forward in the treatment of peritoneal carcinomatosis from ovarian cancer

Peritoneal carcinomatosis (PC) is a common outcome of epithelial ovarian carcinoma and is the leading cause of death for these patients. Tumor location, extent, peculiarities of the microenvironment, and the development of drug resistance are the main challenges that need to be addressed to improve therapeutic outcome. The development of new procedures such as HIPEC (Hyperthermic Intraperitoneal Chemotherapy) and PIPAC (Pressurized Intraperitoneal Aerosol Chemotherapy) have enabled locoregional delivery of chemotherapeutics, while the increasingly efficient design and development of advanced drug delivery micro and nanosystems are helping to promote tumor targeting and penetration and to reduce the side effects associated with systemic chemotherapy administration. The possibility of combining drug-loaded carriers with delivery via HIPEC and PIPAC represents a powerful tool to improve treatment efficacy, and this possibility has recently begun to be explored. This review will discuss the latest advances in the treatment of PC derived from ovarian cancer, with a focus on the potential of PIPAC and nanoparticles in terms of their application to develop new therapeutic strategies and future prospects.

Effects of Co-Culture EBV-miR-BART1-3p on Proliferation and Invasion of Gastric Cancer Cells Based on Exosomes

AIM

EBV encodes at least 44 miRNAs involved in immune regulation and disease progression. Exosomes can be used as carriers of EBV-miRNA-BART intercellular transmission and affect the biological behavior of cells. We characterized exosomes and established a co-culture experiment of exosomes to explore the mechanism of miR-BART1-3p transmission through the exosome pathway and its influence on tumor cell proliferation and invasion.

MATERIALS AND METHODS

Exosomes of EBV-positive and EBV-negative gastric cancer cells were characterized by transmission electron microscopy. NanoSight and Western blotting, and miRNA expression profiles in exosomes were sequenced with high throughput. Exosomes with high or low expression of miR-BART1-3p were co-cultured with AGS cells to study the effects on proliferation, invasion, and migration of gastric cancer cells. The target genes of EBV-miR-BART1-3p were screened and predicted by PITA, miRanda, RNAhybrid, virBase, and DIANA-TarBase v.8 databases, and the expression of the target genes after co-culture was detected by qPCR.

RESULTS

The exosomes secreted by EBV-positive and negative gastric cancer cells range in diameter from 30 nm to 150 nm and express the exosomal signature proteins CD9 and CD63. Small RNA sequencing showed that exosomes expressed some human miRNAs, among which hsa-miR-23b-3p, hsa-miR-320a-3p, and hsa-miR-4521 were highly expressed in AGS-exo; hsa-miR-21-5p, hsa-miR-148a-3p, and hsa-miR-7-5p were highly expressed in SNU-719-exo. All EBV miRNAs were expressed in SNU-719 cells and their exosomes, among which EBV-miR-BART1-5p, EBV-miR-BART22, and EBV-miR-BART16 were the highest in SNU-719 cells; EBV-miR-BART1-5p, EBV-miR-BART10-3p, and EBV-miR-BART16 were the highest in SNU-719-exo. After miR-BART1-3p silencing in gastric cancer cells, the proliferation, healing, migration, and invasion of tumor cells were significantly improved. Laser confocal microscopy showed that exosomes could carry miRNA into recipient cells. After co-culture with miR-BART1-3p silenced exosomes, the proliferation, healing, migration, and invasion of gastric cancer cells were significantly improved. The target gene of miR-BART1-3p was FAM168A, MACC1, CPEB3, ANKRD28, and USP37 after screening by a targeted database. CPEB3 was not expressed in all exosome co-cultured cells, while ANKRD28, USP37, MACC1, and FAM168A were all expressed to varying degrees. USP37 and MACC1 were down-regulated after up-regulation of miR-BART1-3p, which may be the key target genes for miR-BART1-3p to regulate the proliferation of gastric cancer cells through exosomes.

CONCLUSIONS

miR-BART1-3p can affect the growth of tumor cells through the exosome pathway. The proliferation, healing, migration, and invasion of gastric cancer cells were significantly improved after co-culture with exosomes of miR-BART1-3p silenced expression. USP37 and MACC1 may be potential target genes of miR-BART1-3p in regulating cell proliferation.

Gastric cancer-derived exosomes facilitate pulmonary metastasis by activating ERK-mediated immunosuppressive macrophage polarization

Gastric cancer (GC) with pulmonary metastasis is one of the deadliest diseases in the world; however, the underlying pathological mechanisms and potential therapeutic targets remain to be elucidated. As exosomes play indispensable roles in the formation of premetastatic niches (PMN) and cancer metastasis. Therefore, investigating the underlying mechanisms of exosome-mediated pulmonary metastasis of GC may shed new light on identifying novel therapeutic targets for GC treatment. GC-derived exosomes were isolated from the conditioned medium of mouse forestomach carcinoma (MFC) cell line. The effects of MFC-derived exosomes on pulmonary macrophage polarization were analyzed by reverse- transcription polymerase chain reaction and flow cytometry. Expression of PD-L1 and other proteins was evaluated by Western blot. Exosomal microRNAs (miRNAs) were analyzed by microarray. GC-derived exosomes (GC-exo) accumulated in high numbers in the lungs and were ingested by macrophages. The extracellular-signal-regulated kinase (ERK) signaling pathway was activated by GC-exo, inducing macrophage immunosuppressive-phenotype differentiation and increased PD-L1 expression. miRNA-sequencing identified 130 enriched miRNAs in GC-exo. Among the enriched miRNAs, miR-92a-3p plays a major role in activating ERK signaling via inhibition of PTEN expression. In addition, inhibiting ERK signaling with PD98059 significantly reduced the expression of PD-L1 in macrophages and, therefore, reversed the immunosuppressive PMN and inhibited the colonization of GC cells in the lungs. This study identified a novel mechanism of GC-exo mediated PD-L1 expression in lung macrophages that facilitates lung PMN formation and GC pulmonary metastasis, which also provided a potential therapeutic target for GC with pulmonary metastasis treatment.

Shaping Up the Tumor Microenvironment: Extracellular Vesicles as Important Intermediaries in Building a Tumor-Supportive Cellular Network

A tumor is not just comprised of cancer cells but also a heterogeneous group of infiltrating and resident host cells, as well as their secreted factors that form the extracellular matrix [...].

Exosomes released from cisplatin-resistant ovarian cancer cells modulate the reprogramming of cells in tumor microenvironments toward the cancerous cells

Exosomes released from cancer cells are involved in the reorganization of the tumor microenvironment which is the essential aspect of cancer pathogenesis. The intercommunications between cancer cells and diverse cell types in the microenvironment are accomplished by exosomes in ovarian cancer. Internalization pathway, intracellular fate, and biological functions in recipient cells mediated by exosomes released from cisplatin-resistant A2780cis have been studied. Also, histopathological evaluation of tumor, ovary, liver tissues and lymph nodes in vivo studies have been performed. The recipient cells internalized the exosomes via active uptake mechanisms, as shown by confocal microscopy. However, inhibitor studies and flow cytometry analysis showed that each recipient cell line used different uptake pathways. Also, confocal microscopy imaging indicated that the internalized exosomes trapped in the endosomes or phagosomes were distributed to the different cellular compartments including ER, Golgi, and lysosome. The transfer of exosomal oncogenic cargo into the cells modified the intracellular signaling of recipient cells including invasion and metastasis by Boyden-Chamber assay, proliferation by ATP analysis, epithelial-mesenchymal transition (EMT) markers at protein and mRNA levels by western blotting and real-time PCR, and protein kinases in the phospho-kinase array. This remodeling contributed to the initiation of carcinogenesis in ovarian epithelial and peritoneal mesothelial cells, and the progression of carcinogenesis in ovarian cancer cells. In addition, intraperitoneal tumor model studies show that exosomes released from cisplatin-resistant A2780cis cells may play role in the enlargement of lymph nodes, and tumor formations integrated with the liver, attached to the stomach and in the ovarian tissues.

Isolation and Characterization of Extracellular Vesicles from Gastric Juice

Simple Summary

Gastric cancer (GC) is one of the most common cancers and the fifth leading cause of cancer-related deaths worldwide. The steadily growing interest in secreted extracellular vesicles (EVs) is related to their ability to carry a variety of biologically active molecules, which can be used as markers for liquid noninvasive diagnosis of malignant neoplasms. For these applications, blood is the most widely used source of EVs. However, this body fluid contains an extremely heterogeneous mixture of EVs originating from different types of normal cells and tissues. The aim of this study was to assess the possibility of using gastric juice (GJ) as an alternative source of EVs since it is expected to be enriched in vesicles of tumor origin. We validated the presence of EVs in GJ using transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and western-blot analysis of exosomal markers, showed for the first time the feasibility of their isolation by ultracentrifugation and demonstrated the prospect of using GJ-derived EVs as a source of GC miRNA markers.

Abstract

EVs are involved in local and distant intercellular communication and play a vital role in cancer development. Since EVs have been found in almost all body fluids, there are currently active attempts for their application in liquid diagnostics. Blood is the most commonly used source of EVs for the screening of cancer markers, although the percentage of tumor-derived EVs in the blood is extremely low. In contrast, GJ, as a local biofluid, is expected to be enriched with GC-associated EVs. However, EVs from GJ have never been applied for the screening and are underinvestigated overall. Here we show that EVs can be isolated from GJ by ultracentrifugation. TEM analysis showed high heterogeneity of GJ-derived EVs, including those with exosome-like size and morphology. In addition to morphological diversity, EVs from individual GJ samples differed in the composition of exosomal markers. We also show the presence of stomatin within GJ-derived EVs for the first time. The first conducted comparison of miRNA content in EVs from GC patients and healthy donors performed using a pilot sampling revealed the significant differences in several miRNAs (-135b-3p, -199a-3p, -451a). These results demonstrate the feasibility of the application of GJ-derived EVs for screening for miRNA GC markers.

Emerging role of exosomes in cancer progression and tumor microenvironment remodeling

Cancer is one of the leading causes of death worldwide, and the factors responsible for its progression need to be elucidated. Exosomes are structures with an average size of 100 nm that can transport proteins, lipids, and nucleic acids. This review focuses on the role of exosomes in cancer progression and therapy. We discuss how exosomes are able to modulate components of the tumor microenvironment and influence proliferation and migration rates of cancer cells. We also highlight that, depending on their cargo, exosomes can suppress or promote tumor cell progression and can enhance or reduce cancer cell response to radio- and chemo-therapies. In addition, we describe how exosomes can trigger chronic inflammation and lead to immune evasion and tumor progression by focusing on their ability to transfer non-coding RNAs between cells and modulate other molecular signaling pathways such as PTEN and PI3K/Akt in cancer. Subsequently, we discuss the use of exosomes as carriers of anti-tumor agents and genetic tools to control cancer progression. We then discuss the role of tumor-derived exosomes in carcinogenesis. Finally, we devote a section to the study of exosomes as diagnostic and prognostic tools in clinical courses that is important for the treatment of cancer patients. This review provides a comprehensive understanding of the role of exosomes in cancer therapy, focusing on their therapeutic value in cancer progression and remodeling of the tumor microenvironment.

Role of Peritoneal Mesothelial Cells in the Progression of Peritoneal Metastases

Peritoneal metastatic cancer comprises a heterogeneous group of primary tumors that originate in the peritoneal cavity or metastasize into the peritoneal cavity from a different origin. Metastasis is a characteristic of end-stage disease, often indicative of a poor prognosis with limited treatment options. Peritoneal mesothelial cells (PMCs) are a thin layer of cells present on the surface of the peritoneum. They display differentiated characteristics in embryonic development and adults, representing the first cell layer encountering peritoneal tumors to affect their progression. PMCs have been traditionally considered a barrier to the intraperitoneal implantation and metastasis of tumors; however, recent studies indicate that PMCs can either inhibit or actively promote tumor progression through distinct mechanisms. This article presents a review of the role of PMCs in the progression of peritoneum implanted tumors, offering new ideas for therapeutic targets and related research.

Gastric cancer cell-derived extracellular vesicles elevate E2F7 expression and activate the MAPK/ERK signaling to promote peritoneal metastasis through the delivery of SNHG12

Cancer cell-derived extracellular vesicles (EVs) have extensive application in the formation of their environment, including metastasis. This study explored the ability of gastric cancer (GC) cell-derived EVs-mediated microRNA-129-5p/E2F transcription factor 7/mitogen-activated protein kinase/extracellular regulated protein kinase (miR-129-5p/E2F7/MAPK/ERK) axis to affect the peritoneal metastasis of GC by delivering lncRNA small nucleolar RNA host gene 12 (SNHG12). EV-derived lncRNA and SNHG12/miR-129-5p/E2F7 network were determined by bioinformatics analysis. The regulatory relationship among SNHG12, miR-129-5p, and E2F7 was verified using a combination of dual-luciferase reporter gene, RNA immunoprecipitation, and RNA pull-down assays. The SNHG12, miR-129-5p, and E2F7 expression was measured by RT-qPCR. After GC cell-derived EVs were isolated and co-cultured with human peritoneal mesothelial cells (HPMCs), the uptake of EVs by HPMCs was observed under laser scanning confocal microscopy. Cell viability and apoptosis were examined using cell counting kit-8 and flow cytometry, respectively. Western blot analysis was performed to measure the mesothelial–mesenchymal transition (MMT)-related protein expression. The pathological and morphological characteristics of metastatic tumors in nude mice were observed by hematoxylin–eosin staining. A high SNHG12 expression was correlated with the poor prognosis of patients with GC. GC-derived EVs led to increased HPMC apoptosis and MMT by transferring SNHG12, whereas the knockdown of SNHG12 annulled the aforementioned results. SNHG12 sponged miR-129-5p to boost E2F7 expression and activate the MAPK/ERK signaling, thus inducing HPMC apoptosis and MMT. In vivo experiments further verified that EVs derived from GC cells promoted peritoneal metastasis in nude mice. GC cell-derived EVs elevated the E2F7 expression and activated the MAPK/ERK signaling to promote peritoneal metastasis through the delivery of SNHG12.

Crosstalk of tumor stromal cells orchestrates invasion and spreading of gastric cancer

Tumors contain various stromal cells that support cancer progression. Some types of cancer, such as scirrhous gastric cancer, are characterized by large areas of fibrosis accompanied by cancer-associated fibroblasts (CAFs). Asporin (ASPN) is a small leucine-rich proteoglycan highly expressed in CAFs of various tumors. ASPN accelerates CAF migration and invasion, resulting in CAF-led cancer cell invasion. In addition, ASPN further upregulated the expression of genes specific to a characteristic subgroup of fibroblasts in tumors. These cells were preferentially located at the tumor periphery and could be generated by a unique mechanism involving the CAF-mediated education of normal fibroblasts (CEFs). In this review, we at first describe recent findings regarding the function of ASPN in the tumor microenvironment, as well as the mechanism involved in the generation of CEFs. CAFs are derived from heterogeneous origins besides resident normal fibroblasts. Among them, CAFs derived from mesothelial cells (mesothelial cell-derived CAF [MC-CAFs]) play pivotal roles in peritoneal carcinomatosis. We observed that MC-CAFs on the surfaces of organs also participate in tumor formation by infiltrating into the parenchyma, promoting local invasion by gastric cancers. This review also highlights the potential functions of macrophages in the formation of MC-CAFs in gastric cancers, by transfer the contents of cancer cell-derived extracellular vesicles.

Extracellular Vesicles Promote the Formation of Pre-Metastasis Niche in Gastric Cancer

Globally, gastric cancer (GC) ranks fourth in the incidence of malignant tumors. The early clinical manifestations of GC lack specificity. Most patients are already at an advanced stage when they are first diagnosed, and their late progression is mainly due to peritoneal metastasis. A pre-metastatic microenvironment is formed, before the macroscopic tumor metastasis. Extracellular vesicles (EVs) are nanovesicles released by cells into body fluids. Recent studies have shown that EVs can affect the tumor microenvironment by carrying cargos to participate in cell-to-cell communication. EVs derived from GC cells mediate the regulation of the pre-metastasis niche and act as a coordinator between tumor cells and normal stroma, immune cells, inflammatory cells, and tumor fibroblasts to promote tumor growth and metastasis. This review highlights the regulatory role of EVs in the pre-metastatic niche of GC and mulls EVs as a potential biomarker for liquid biopsy.

microRNA-10a-5p from gastric cancer cell-derived exosomes enhances viability and migration of human umbilical vein endothelial cells by targeting zinc finger MYND-type containing 11

Tumor-derived exosomes (exo) could modulate the biological behaviors of human umbilical vein endothelial cells (HUVECs). Here, the role of microRNA (miR)-10a-5p-modified gastric cancer (GC) cells-derived exo for HUVECs was studied. GC tissue specimens were collected, and miR-10a-5p and zinc finger MYND-type containing 11 (ZMYND11) levels were determined. HUVECs interfered with ZMYND11 or miR-10a-5p-related oligonucleotides. Exo was extracted from GC cells (HGC-27 exo), and miR-10a-5p mimic-modified HGC-27 exo were co-cultured with HUVECs. HUVECs viability, migration and angiogenesis were evaluated, and miR-10a-5p/ZMYND11 crosstalk was explored. It was observed that GC patients had raised miR-10a-5p and reduced ZMYND11, and miR-10a-5p negatively mediated ZMYND11 expression. Suppression of miR-10a-5p or overexpression of ZMYND11 inhibited viability, migration and tube formation ability of HUVECs. Notably, miR-10a-5p mimic-modified HGC-27 exo enhanced the viability, migration and tube formation ability of HUVECs, but this effect was impaired after up-regulating ZMYND11. In summary, miR-10a-5p from GC cells-derived exo enhances viability and migration of HUVECs by suppressing ZMYND11.

In sickness and in health: The functional role of extracellular vesicles in physiology and pathology in vivo: Part II: Pathology: Part II: Pathology

It is clear from Part I of this series that extracellular vesicles (EVs) play a critical role in maintaining the homeostasis of most, if not all, normal physiological systems. However, the majority of our knowledge about EV signalling has come from studying them in disease. Indeed, EVs have consistently been associated with propagating disease pathophysiology. The analysis of EVs in biofluids, obtained in the clinic, has been an essential of the work to improve our understanding of their role in disease. However, to interfere with EV signalling for therapeutic gain, a more fundamental understanding of the mechanisms by which they contribute to pathogenic processes is required. Only by discovering how the EV populations in different biofluids change-size, number, and physicochemical composition-in clinical samples, may we then begin to unravel their functional roles in translational models in vitro and in vivo, which can then feedback to the clinic. In Part II of this review series, the functional role of EVs in pathology and disease will be discussed, with a focus on in vivo evidence and their potential to be used as both biomarkers and points of therapeutic intervention.

Diabetes mellitus contribution to the remodeling of the tumor microenvironment in gastric cancer

Compelling pieces of evidence derived from both clinical and experimental research has demonstrated the crucial contribution of diabetes mellitus (DM) as a risk factor associated with increased cancer incidence and mortality in many human neoplasms, including gastric cancer (GC). DM is considered a systemic inflammatory disease and therefore, this inflammatory status may have profound effects on the tumor microenvironment (TME), particularly by driving many molecular mechanisms to generate a more aggressive TME. DM is an active driver in the modification of the behavior of many cell components of the TME as well as altering the mechanical properties of the extracellular matrix (ECM), leading to an increased ECM stiffening. Additionally, DM can alter many cellular signaling mechanisms and thus favoring tumor growth, invasion, and metastatic potential, as well as key elements in regulating cellular functions and cross-talks, such as the microRNAs network, the production, and cargo of exosomes, the metabolism of cell stroma and resistance to hypoxia. In the present review, we intend to highlight the mechanistic contributions of DM to the remodeling of TME in GC.

Exosomal ANXA2 derived from ovarian cancer cells regulates epithelial-mesenchymal plasticity of human peritoneal mesothelial cells

Ovarian cancer, one of the malignant gynaecological tumours with the highest mortality rate among female reproductive system, is prone to metastasis, recurrence and chemotherapy resistance, causing a poor prognosis. Exosomes can regulate the epithelial‐mesenchymal plasticity of tumour cells, remodel surrounding tumour microenvironment, and affect tumour cell proliferation, invasion and metastasis. However, the function and mechanism of exosomes in the intraperitoneal implantation of ovarian cancer remain unclear. In this study, exosomal annexin A2 (ANXA2) derived from ovarian cancer cells was co‐cultured with human peritoneal mesothelial (HMrSV5) cells; functional experiments were conducted to explore the effects of exosomal ANXA2 on the biological behaviour of HMrSV5 and the related mechanisms. This study showed that ANXA2 in ovarian cancer cells can be transferred to HMrSV5 cells through exosomes, exosomal ANXA2 can not only promote the migration, invasion and apoptosis of HMrSV5 cells, but also regulates morphological changes and fibrosis of HMrSV5 cells. Furthermore, ANXA2 promotes the mesothelial‐mesenchymal transition (MMT) and degradation of the extracellular matrix of HMrSV5 cells through PI3K/AKT/mTOR pathway, finally affects pre‐metastasis microenvironment of ovarian cancer, which provides a new theoretical basis for the mechanism of intraperitoneal implantation and metastasis of ovarian cancer.

Decreased exosome-delivered miR-486-5p is responsible for the peritoneal metastasis of gastric cancer cells by promoting EMT progress

Background

The present study aims to investigate the preliminary mechanism underlying the peritoneal metastasis of gastric cancer cells.

Methods

Exosomes from GC9811 cells (Con-Exo) and from GC9811-P cells (PM-Exo) were extracted by ultracentrifugation, which were identified with transmission electron microscopy (TEM) and nanoparticle trafficking analysis, as well as the expression of CD9, CD63, and CD81 detected by Western blot assay. α-SMA expression was determined by immunofluorescence assay and Western blot assay. The levels of Snail1, E-cadherin, and Actin-related protein 3 (ACTR3) were evaluated by Western blot assay. MiRNA array was performed on exosomes to screen the differentially expressed miRNAs. The expressions of miRNAs, SMAD2, CDK4, and ACTR3 were determined by QRT-PCR. The delivery of miR-486-5p was confirmed by laser confocal detection.

Results

Firstly, TEM, nanoparticle trafficking analysis, and Western blot assays were used to confirm the successful extraction of Con-Exo and PM-Exo. The incubation of Con-Exo and PM-Exo could decrease E-cadherin expression and increase of α-SMA respectively in HMrSV5 cells, with the increased proportion of fusiform cells. More significant changes were observed in PM-Exo-treated HMrSV5 cells. Secondary, compared to Con-Exo, miR-486-5p and miR-132-3p were found downregulated, and miR-132-5p was found upregulated in PM-Exo. The transfection of miR-486-5p and miR-132-3p was observed to suppress EMT, and the transfection of miR-132-3p was observed to induce EMT. Laser confocal detection confirmed the delivery of miR-486-5p from gastric cancer cells to HMrSV5 cells through exosomes. Lastly, the expression of Mothers against decapentaplegic homolog 2 (SMAD2), cyclin-dependent kinase 4 (CDK4), and ACTR3 was found to be downregulated via miR-486-5p.

Conclusion

Decreased delivery of miR-486-5p via exosomes might be responsible for the peritoneal metastasis of gastric cancer cells by promoting epithelial-mesenchymal transition progress.

Clinical Applications of Liquid Biopsy in Gastric Cancer

Liquid biopsy represents an exciting new area in the field of cancer diagnosis and management, offering a less invasive and more convenient approach to obtain a time-point image of the tumor burden and its genomic profile. Samples collected from several body fluids, mostly blood, can be used to gain access to circulating tumor cells and DNA, non-coding RNAs, microRNAs, and exosomes, at any moment, offering a dynamic picture of the tumor. For patients with GC, the use of blood-based biopsies may be particularly beneficial since tissue biopsies are difficult to obtain and cause real distress to the patient. With advantages such as repeatability and minimal invasion, it is no wonder that the field of liquid biopsy has received tremendous attention. However, the abundance of studies, involving a wide range of assays with different principles, prevented for the moment the reproducibility of the results and therefore the translation into the clinic of liquid biopsy. In this review, we present the latest technical development and data on circulating biomarkers available through liquid biopsy in gastric cancer with an emphasis on their clinical utility in areas such as cancer screening, prognostic stratification, and therapeutic management.

The role of transforming growth factor β in upper gastrointestinal cancers: A systematic review

Esophageal and gastric malignancies are associated with poor prognosis, in part due to development of recurrences or metastases after curative treatment. The transforming growth factor β (TGF-β) pathway might play a role in the development of treatment resistance. In this systematic review, we provide an overview of preclinical studies investigating the role of TGF-β in esophageal and gastric malignancies. We systematically searched MEDLINE/PubMed and EMBASE for eligible preclinical studies describing the effect of TGF-β or TGF-β inhibition on hallmarks of cancer, such as proliferation, migration, invasion, angiogenesis and immune evasion. In total, 2107 records were screened and 45 articles were included, using mouse models and 45 different cell lines. TGF-β failed to induce apoptosis in twelve of sixteen tested cell lines. TGF-β could either decrease (five cell lines) or increase proliferation (seven cell lines) in gastric cancer cells, but had no effect in esophageal cancer cells. In all esophageal and all but two gastric cancer cell lines, TGF-β increased migratory, adhesive and invasive capacities. In vivo studies showed increased metastasis in response to TGF-β treatment. Additionally, TGF-β was shown to induce vascular endothelial growth factor production and differentiation of cancer-associated fibroblasts and regulatory T-cells. In conclusion, we found that TGF-β enhances hallmarks of cancer in most gastric and esophageal cancer cell lines, but not in all. Therefore, targeting the TGF-β pathway could be an attractive strategy in patients with gastric or esophageal cancer, but additional clinical trials are needed to define patient groups who would benefit most.

EMMPRIN in extracellular vesicles from peritoneal mesothelial cells stimulates the invasion activity of diffuse-type gastric cancer cells

Peritoneal metastasis of gastric cancer (GC) results in extremely poor prognoses. The peritoneal cavity is covered by a monolayer of peritoneal mesothelial cells (PMCs). Interactions between GC cells and PMCs might play a pivotal role in peritoneal metastasis. Extracellular vesicles (EVs) correlate with intercellular communication. Although intercellular communication between cancer cells and PMCs might be associated with the peritoneal metastatic process, the role of EVs from PMCs remains unclear. We investigated the effects of EVs from PMCs on GC cells. Three GC cell lines (OCUM-12, NUGC-3, and MKN74) and four mesothelial cell lines were used. The effects of EVs derived from the PMCs on the invasion and migration of GC cells were evaluated by Matrigel invasion assay. Factors contained in the PMC EVs were analyzed; extra-cellular matrix metalloproteinase inducer (EMMPRIN) was detected in the EVs. The effects of an EMMPRIN inhibitor on the invasion-stimulating activity of EVs were examined. The EMMPRIN expressions of 110 GCs were evaluated by immunohistochemistry. PMC EVs significantly promoted the invasion of diffuse-type GC cells, i.e., OCUM-12 and NUGC-3 cells. EMMPRIN in the EVs stimulated the invasion of OCUM-12 and NUGC-3 cells. The invasion-stimulating activity of PMC EVs was inhibited by the EMMPRIN inhibitor. A high EMMPRIN expression in PMCs was significantly associated with worse cancer-specific survival and peritoneal-recurrence-free survival. EMMPRIN in EVs from PMCs might stimulate the malignant progression of diffuse-type GC. EMMPRIN might be a useful prognostic marker of recurrence in GC patients.

Exosome-derived noncoding RNAs in gastric cancer: functions and clinical applications

Exosomes are a subpopulation of the tumour microenvironment (TME) that transmit various biological molecules to promote intercellular communication. Exosomes are derived from nearly all types of cells and exist in all body fluids. Noncoding RNAs (ncRNAs) are among the most abundant contents in exosomes, and some ncRNAs with biological functions are specifically packaged into exosomes. Recent studies have revealed that exosome-derived ncRNAs play crucial roles in the tumorigenesis, progression and drug resistance of gastric cancer (GC). In addition, regulating the expression levels of exosomal ncRNAs can promote or suppress GC progression. Moreover, the membrane structures of exosomes protect ncRNAs from degradation by enzymes and other chemical substances, significantly increasing the stability of exosomal ncRNAs. Specific hallmarks within exosomes that can be used for exosome identification, and specific contents can be used to determine their origin. Therefore, exosomal ncRNAs are suitable for use as diagnostic and prognostic biomarkers or therapeutic targets. Regulating the biogenesis of exosomes and the expression levels of exosomal ncRNAs may represent a new way to block or eradicate GC. In this review, we summarized the origins and characteristics of exosomes and analysed the association between exosomal ncRNAs and GC development.

The distinct roles of exosomes in tumor-stroma crosstalk within gastric tumor microenvironment

Gastric cancer (GC) development is a complex process displaying polytropic cell and molecular landscape within gastric tumor microenvironment (TME). Stromal cells in TME, including fibroblasts, endothelial cells, mesenchymal stem cells, and various immune cells, support tumor growth, metastasis, and recurrence, functioning as the soil for gastric tumorigenesis. Importantly, exosomes secreted by either stromal cells or tumor cells during tumor-stroma crosstalk perform as crucial transporter of agents including RNAs and proteins for cell-cell communication in GC pathogenesis. Therefore, given the distinct roles of exosomes secreted by various cell types in GC TME, increasing evidence has indicated that exosomes present as new biomarkers for GC diagnosis and prognosis and shed light on novel approaches for GC treatment.

Comprehensive Roles and Future Perspectives of Exosomes in Peritoneal Metastasis of Gastric Cancer

Gastric cancer (GC) is one of the most prevalent digestive malignancies. A great number of patients at first visit or post curative resections are diagnosed with widespread metastasis within the peritoneal cavity. Overwhelming evidence has demonstrated that exosomes, a variety of biologically functional extracellular vesicles comprising active factors, mediate the progression and metastasis of GC. Although the regulatory mechanisms of exosomes remain fairly elusive, they are responsible for intercellular communication between tumor cells and normal stroma, cancer-related fibroblasts, immune cells within the primary tumor and metastatic niche. In this review, we provide new insight into the molecular signatures of GC-associated exosomes in reprogramming the tumor microenvironment and the subsequent promotion of peritoneal metastasis—including infiltration of the gastric wall, implantation of tumor cells onto the pre-metastatic peritoneum, and remodeling of the pre-metastatic niche. Based on this review, we hope to draw a more general conclusion for the functions of exosomes in the progression and peritoneal metastasis of GC and highlight the future perspective on strategies targeting exosomes in prognostic biomarkers and therapy for peritoneal metastasis.

Role of Exosomal Non-coding RNAs in Gastric Cancer: Biological Functions and Potential Clinical Applications

Gastric cancer (GC) is one of the most common fatal cancers worldwide. The communication between GC and other cells in the GC microenvironment directly affects GC progression. Recently, exosomes have been revealed as new players in intercellular communication. They play an important role in human health and diseases, including cancer, owing to their ability to carry various bioactive molecules, including non-coding RNAs (ncRNAs). NcRNAs, including micro RNAs, long non-coding RNAs, and circular RNAs, play a significant role in various pathophysiological processes, especially cancer. Increasing evidence has shown that exosomal ncRNAs are involved in the regulation of tumor proliferation, invasion, metastasis, angiogenesis, immune regulation, and treatment resistance in GC. In addition, exosomal ncRNAs have promising potential as diagnostic and prognostic markers for GC. Considering the biocompatibility of exosomes, they can also be used as biological carriers for targeted therapy. This review summarizes the current research progress on exosomal ncRNAs in gastric cancer, focusing on their biological role in GC and their potential as new biomarkers for GC and therapeutics. Our review provides insight into the mechanisms involved in GC progression, which may provide a new point cut for the discovery of new diagnostic markers and therapeutic strategies.

The role of endolysosomal trafficking in anticancer drug resistance

Multidrug resistance (MDR) remains a major obstacle towards curative treatment of cancer. Despite considerable progress in delineating the basis of intrinsic and acquired MDR, the underlying molecular mechanisms remain to be elucidated. Emerging evidences suggest that dysregulation in endolysosomal compartments is involved in mediating MDR through multiple mechanisms, such as alterations in endosomes, lysosomes and autophagosomes, that traffic and biodegrade the molecular cargo through macropinocytosis, autophagy and endocytosis. For example, altered lysosomal pH, in combination with transcription factor EB (TFEB)-mediated lysosomal biogenesis, increases the sequestration of hydrophobic anti-cancer drugs that are weak bases, thereby producing an insufficient and off-target accumulation of anti-cancer drugs in MDR cancer cells. Thus, the use of well-tolerated, alkalinizing compounds that selectively block Vacuolar H⁺-ATPase (V-ATPase) may be an important strategy to overcome MDR in cancer cells and increase chemotherapeutic efficacy. Other mechanisms of endolysosomal-mediated drug resistance include increases in the expression of lysosomal proteases and cathepsins that are involved in mediating carcinogenesis and chemoresistance. Therefore, blocking the trafficking and maturation of lysosomal proteases or direct inhibition of cathepsin activity in the cytosol may represent novel therapeutic modalities to overcome MDR. Furthermore, endolysosomal compartments involved in catabolic pathways, such as macropinocytosis and autophagy, are also shown to be involved in the development of MDR. Here, we review the role of endolysosomal trafficking in MDR development and discuss how targeting endolysosomal pathways could emerge as a new therapeutic strategy to overcome chemoresistance in cancer.

Exosomes Promote Pre-Metastatic Niche Formation in Gastric Cancer

Gastric cancer has a high rate of metastasis, during which pre-metastatic niches (PMN) provide a supportive environment for the upcoming tumor cells. Exosomes are bilayer vesicles secreted by cells containing biological information that mediates communication between cells. Using exosomes, gastric cancer cells establish PMN remotely in multifarious perspectives, including immunosuppression, stroma remodeling, angiogenesis, mesothelial mesenchymal transformation, and organotropism. In turn, the cell components in PMN secrete exosomes that interact with each other and provide onco-promoting signals. In this review, we highlight the role of exosomes in PMN formation in gastric cancer and discuss their potential values in gastric cancer metastasis diagnosis, prevention, and treatment.

The Interaction between Reactive Peritoneal Mesothelial Cells and Tumor Cells via Extracellular Vesicles Facilitates Colorectal Cancer Dissemination

Advanced colorectal cancer (CRC) is highly metastatic and often results in peritoneal dissemination. The extracellular vesicles (EVs) released by cancer cells in the microenvironment are important mediators of tumor metastasis. We investigated the contribution of EV-mediated interaction between peritoneal mesothelial cells (MCs) and CRC cells in generating a pro-metastatic environment in the peritoneal cavity. Peritoneal MCs isolated from peritoneal lavage fluids displayed high CD44 expression, substantial mesothelial-to-mesenchymal transition (MMT) and released EVs that both directed tumor invasion and caused reprogramming of secretory profiles by increasing TGF-β1 and uPA/uPAR expression and MMP-2/9 activation in tumor cells. Notably, the EVs released by tumor cells induced apoptosis by activating caspase-3, peritoneal MC senescence, and MMT, thereby augmenting the tumor-promoting potential of these cells in the peritoneal cavity. By using pantoprazole, we reduced the biogenesis of EVs and their pro-tumor functions. In conclusion, our findings provided evidence of underlying mechanisms of CRC dissemination driven by the interaction of peritoneal MCs and tumor cells via the EVs released in the peritoneal cavity, which may have important implications for the clinical management of patients.

The Emerging Role of Liquid Biopsy in Gastric Cancer

(1) Background: Liquid biopsy (LB) is a novel diagnostic method with the potential of revolutionizing the prevention, diagnosis, and treatment of several solid tumors. The present paper aims to summarize the current knowledge and explore future possibilities of LB in the management of metastatic gastric cancer. (2) Methods: This narrative review examined the most recent literature on the use of LB-based techniques in metastatic gastric cancer and the current LB-related clinical trial landscape. (3) Results: In gastric cancer, the detection of circulating cancer cells (CTCs) has been recognized to have a prognostic role in all the disease stages. In the setting of localized disease, cell-free DNA (cfDNA) and circulating tumor DNA (ctDNA) qualitative and quantitative detection have the potential to inform on the risk of cancer recurrence and metastatic dissemination. In addition, gastric cancer-released exosomes may play an essential part in metastasis formation. In the metastatic setting, the levels of cfDNA show a positive correlation with tumor burden. There is evidence that circulating tumor microemboli (CTM) in the blood of metastatic patients is an independent prognostic factor for shorter overall survival. Gastric cancer-derived exosomal microRNAs or clonal mutations and copy number variations detectable in ctDNA may contribute resistance to chemotherapy or targeted therapies, respectively. There is conflicting and limited data on CTC-based PD-L1 verification and cfDNA-based Epstein-Barr virus detection to predict or monitor immunotherapy responses. (4) Conclusions: Although preliminary studies analyzing LBs in patients with advanced gastric cancer appear promising, more research is required to obtain better insights into the molecular mechanisms underlying resistance to systemic therapies. Moreover, validation and standardization of LB methods are crucial before introducing them in clinical practice. The feasibility of repeatable, minimally invasive sampling opens up the possibility of selecting or dynamically changing therapies based on prognostic risk or predictive biomarkers, such as resistance markers. Research is warranted to exploit a possible transforming area of cancer care.

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.

Molecular risk markers related to local tumor recurrence at histological margin-free endoscopically resected early gastric cancers: A pilot study

Local recurrences in early gastric cancers (EGCs) after complete endoscopic submucosal dissection (ESD) remain problematic. Here, we investigated the spatially sequential molecular changes in various cancer-related proteins along the axis of the histologically clear but recurrent resection margins (TRM) to determine the appropriate tumor-free margin distance and potential molecular risk markers related to local recurrence. Five eligible patients with recurrent EGCs after complete ESD were selected from 548 EGC patients. The specimens, including recurrent resection margin axis, were divided into 5 zones. Digital spatial profiling assay was performed to quantify the expression level of 31 cancer-related proteins along each zone. p-Chk1 level was significantly reduced in TRM zone than non-recurrent resection margin. The expression of p44/42 ERK and p-Chk1 were significantly decreased along the lateral axis of the recurrent resection margin, with no significance toward the normal zone, which may suggest that p44/42 ERK and p-Chk1 may be involved in the recurrent side compared to non-recurrent margin. Although we could not evaluate more than 5.5 mm, the significant linear decreases in p44/42 ERK and p-Chk1 were maintained until at least 5.5 mm from the tumor zone in the TRM direction. We estimated the possible margin distance using scatterplots and linear regression analyses, which also showed the estimated distance more than 5.5 mm. In conclusion, the p-Chk1 and p44/42 ERK may be potential candidates of molecular risk markers that may be related to the local recurrence after complete ESD, and a tumor-free distance of 5.5 mm is not enough for safety margin.

Exosomes and extracellular vesicles: Rethinking the essential values in cancer biology

Extracellular vesicles (EVs) such as exosomes are released by all living cells and contain diverse bioactive molecules, including nucleic acids, proteins, lipids, and metabolites. Accumulating evidence of EV-related functions has revealed that these tiny vesicles can mediate specific cell-to-cell communication. Within the tumor microenvironment, diverse cells are actively interacting with their surroundings via EVs facilitating tumor malignancy by regulating malignant cascades including angiogenesis, immune modulation, and metastasis. This review summarizes the recent studies of fundamental understandings of EVs from the aspect of EV heterogeneity and highlights the role of EVs in the various steps from oncogenic to metastatic processes. The recognition of EV subtypes is necessary to identify which pathways can be affected by EVs and which subtypes can be targeted in therapeutic approaches or liquid biopsies.

Exosomal miR-122-5p inhibits tumorigenicity of gastric cancer by downregulating GIT1

BACKGROUND

microRNAs (miRNAs) are non-coding RNAs with important roles in the progression of human cancers, including gastric cancer. Exosomes are extracellular vesicles, which could transfer numerous noncoding RNAs, such as miRNAs. Here, in our study, we intended to investigate the role of exosomal miR-122-5p in gastric cancer progression.

METHODS

Exosomes were isolated utilizing commercial kit or ultracentrifugation. Biomarkers of exosomes or epithelia-mesenchymal transition (EMT) were monitored by western blot. Expression levels of miR-122-5p and G-protein-coupled receptor kinase interacting protein-1 (GIT1) were evaluated by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) or western blot. Cell proliferation and apoptosis were assessed by colony formation assay, methyl thiazolyl tetrazolium assay and flow cytometry. Cell metastasis was evaluated via Transwell assay. The interaction between miR-122-5p and GIT1 was validated by dual-luciferase reporter assay. Furthermore, tumor growth in vivo was detected by xenograft assay.

RESULTS

Exosomes were successfully isolated. MiR-122-5p was downregulated in exosomes derived from the serum of gastric cancer patients. Exosomal miR-122-5p could hinder gastric cancer cell proliferation and metastasis in vitro and tumor growth in vivo. Knockdown of GIT1 also inhibited gastric cancer cell proliferation and metastasis. Exosomal miR-122-5p targeted GIT1 to alter cellular behaviors of gastric cancer cells.

CONCLUSION

Exosomal miR-122-5p suppressed gastric cancer progression by targeting GIT1.

Delivery Efficacy Differences of Intravenous and Intraperitoneal Injection of Exosomes: Perspectives from Tracking Dye Labeled and MiRNA Encapsulated Exosomes

BACKGROUND

Exosomes are cell-derived nanovesicles that play vital roles in intercellular communication. Recently, exosomes are recognized as promising drug delivery vehicles. Up till now, how the in vivo distribution of exosomes is affected by different administration routes has not been fully understood.

METHODS

In the present study, in vivo distribution of exosomes following intravenous and intraperitoneal injection approaches was systemically analyzed by tracking the fluorescence-labeled exosomes and qPCR analysis of C. elegans specific miRNA abundance delivered by exosomes in different organs.

RESULTS

The results showed that exosomes administered through tail vein were mostly taken up by the liver, spleen and lungs while exosomes injected intraperitoneally were more dispersedly distributed. Besides the liver, spleen, and lungs, intraperitoneal injection effectively delivered exosomes into the visceral adipose tissue, making it a promising strategy for obesity therapy. Moreover, the results from fluorescence tracking and qPCR were slightly different, which could be explained by systemic errors.

CONCLUSION

Together, our study reveals that different administration routes cause a significant differential in vivo distribution of exosomes, suggesting that optimization of the delivery route is prerequisite to obtain rational delivery efficiency in detailed organs.

Extracellular Vesicles as Potential Biomarkers for Early Detection and Diagnosis of Pancreatic Cancer

Pancreatic carcinoma (PC) is highly metastatic, and it tends to be detected at advanced stages. Identifying and developing biomarkers for early detection of PC is crucial for a potentially curative treatment. Extracellular vesicles (EVs) are bilayer lipid membrane-structured nanovesicles found in various human bodily fluids, and they play important roles in tumor biogenesis and metastasis. Cancer-derived EVs are enriched with DNA, RNA, protein, and lipid, and they have emerged as attractive diagnostic biomarkers for early detection of PC. In this article, we provided an overview of the cell biology of EVs and their isolation and analysis, and their roles in cancer pathogenesis and progression. Multiplatform analyses of plasma-based exosomes for genomic DNA, micro RNA, mRNA, circular RNA, and protein for diagnosis of PC were critically reviewed. Numerous lines of evidence demonstrate that liquid biopsy with analysis of EV-based biomarkers has variable performance for diagnosis of PC. Future investigation is indicated to optimize the methodology for isolating and analyzing EVs and to identify the combination of EV-based biomarkers and other clinical datasets, with the goal of improving the predictive value, sensitivity, and specificity of screening tests for early detection and diagnosis of PC.

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.