SCARA5 in bone marrow stromal cell-derived exosomes inhibits colorectal cancer progression by inactivating the PI3K/Akt pathway

Colorectal cancer (CRC) is the fourth most frequently diagnosed cancer worldwide. Bone marrow stromal cells (BMSCs) play an essential role in tumor development by secreting exosomes. Scavenger receptor class A member 5 (SCARA5) is a newly identified tumor suppressor. This study aimed to investigate the effects of BMSCs-derived exosomes (BMSCs-Exos) on CRC development and to explore their regulatory mechanisms. BMSCs-Exos showed an oval-shaped, bilayer membrane structure. BMSCs-Exos inhibited growth and motility of CRC cells, while BMSCs-Exos with SCARA5 knockdown significantly promoted cell proliferation and movement. Exosomal SCARA5 also effectively suppressed colorectal tumor growth in mouse xenografts. Further analysis revealed that exosomal SCARA5 inhibited the phosphorylation of protein kinase B and phosphoinositide 3-kinase in both CRC cells and tumors. In conclusion, SCARA5 in BMSCs-Exos inhibited CRC progression by inactivating PI3K/Akt, thus suggesting the potential clinical application of SCARA5-containing BMSCs-Exos for CRC treatment.     

Proteomic analysis of microvesicles derived from human colorectal cancer ascites

The presence of malignant ascites in the peritoneal cavity is a poor prognostic indicator of low survival rate. Various cancer cells, including those of colorectal cancer (CRC), release microvesicles (exosomes) into surrounding tissues and peripheral circulation including malignant ascites. Although recent progress has revealed that microvesicles play multiple roles in tumor progression, the protein composition and the pathological function of malignant ascites-derived microvesicles are still unknown. Here, we report the first global proteomic analyses of highly purified microvesicles derived from human CRC ascites. With 1-D SDS-PAGE and nano-LC-MS/MS analyses, we identified a total of 846 microvesicular proteins from ascites of three CRC patients with high confidence; 384 proteins were identified in at least two patients. We identified proteins that might function in tumor progression via disruption of epithelial polarity, migration, invasion, tumor growth, immune modulation, and angiogenesis. Furthermore, we identified several potential diagnostic markers of CRC including colon-specific surface antigens. Our proteomic analyses will help to elucidate diverse functions of microvesicles in cancer progression and will aid in the development of novel diagnostic tools for CRC.     

microRNA-16-5p-containing exosomes derived from bone marrow-derived mesenchymal stem cells inhibit proliferation,migration, and invasion,while promoting apoptosis of colorectal cancer cells by downregulating ITGA2

Colorectal cancer (CRC) is a form of cancer developing from either the colon or rectum. Nowadays, research supports the functionality of exosome expressing microRNAs (miRNAs) as potential biomarker for various cancers including CRC. This study was performed with the intent of investigating the roles of both bone marrow-derived mesenchymal stem cells (BMSCs) and exosomal miR-16-5p in CRC by regulating integrin α2 (ITGA2). A microarray-based analysis was conducted to screen the CRC-associated differentially expressed genes (DEGs) as well as potential regulatory miRNAs. Next, the role of miR-16-5p in terms of its progression in association with CRC was determined. Subsequently, CRC cells were exposed to exosomes secreted by BMSCs transfected with miR-16-5p, isolated and cocultured with CRC cells in an attempt to identify the role of exosomes. Effects of BMSCs-derived exosomes overexpressing miR-16-5p on biological functions of CRC cells and tumorigenicity were all subsequently detected. Effects of miR-16-5p treated with CRC cells in regard to CRC in vivo were also measured. ITGA2 was overexpressed, while miR-16-5p was poorly expressed in CRC cells and miR-16-5p targeted ITGA2. The in vitro experiments revealed that the BMSCs-derived exosomes overexpressing miR-16-5p inhibited proliferation, migration, and invasion, while simultaneously stimulating the apoptosis of the CRC cells via downregulation of ITGA2. Furthermore, the results of in vivo experiments confirmed that the BMSCs-derived exosomes overexpressing miR-16-5p repressed the tumor growth of CRC. Collectively, BMSCs-derived exosomes overexpressing miR-16-5p restricted the progression of CRC by downregulating ITGA2.     

Oncogenic and Non‐Malignant Pancreatic Exosome Cargo Reveal Distinct Expression of Oncogenic and Prognostic Factors Involved in Tumor Invasion and Metastasis

Exosomes are small extracellular membrane vesicles important in intercellular communication, with their oncogenic cargo attributed to tumor progression and pre‐metastatic niche formation. To gain an insight into key differences in oncogenic composition of exosomes, human non‐malignant epithelial and pancreatic cancer cell models and purified and characterized resultant exosome populations are utilized. Proteomic analysis reveals the selective enrichment of known exosome markers and signaling proteins in comparison to parental cells. Importantly, valuable insights into oncogenic exosomes (362 unique proteins in comparison to non‐malignant exosomes) of key metastatic regulatory factors and signaling molecules fundamental to pancreatic cancer progression (KRAS, CD44, EGFR) are provided. It is reported that oncogenic exosomes contain factors known to regulate the pre‐metastatic niche (S100A4, F3, ITGβ5, ANXA1), clinically‐relevant proteins which correlate with poor prognosis (CLDN1, MUC1) as well as protein networks involved in various cancer hallmarks including proliferation (CLU, CAV1), invasion (PODXL, ITGA3), metastasis (LAMP1, ST14) and immune surveillance escape (B2M). The presence of these factors in oncogenic exosomes offers an understanding of select differences in exosome composition during tumorigenesis, potential components as prognostic and diagnostic biomarkers in pancreatic cancer, and highlights the role of exosomes in mediating crosstalk between tumor and stromal cells.     

Exosomal circRNAs as novel cancer biomarkers: Challenges and opportunities

Identifying high specificity and sensitivity biomarkers has always been the focus of research in the field of non-invasive cancer diagnosis. Exosomes are extracellular vesicles with a lipid bilayer membrane that can be released by all types of cells, which contain a variety of proteins, lipids, and a variety of non-coding RNAs. Increasing research has shown that the lipid bilayer can effectively protect the nucleic acid in exosomes. In cancers, tumor cell-derived exosomal circRNAs can act on target cells or organs through the transport of exosomes, and then participate in the regulation of tumor development and metastasis. Since exosomes exist in various body fluids and circRNAs in exosomes exhibit high stability, exosomal circRNAs have the potential as biomarkers for early and minimally invasive cancer diagnosis and prognosis judgment. In this review, we summarized circRNAs and their biological roles in cancers, with the emerging value biomarkers in cancer diagnosis, disease judgment, and prognosis observation. In addition, we briefly compared the advantages of exosomal circRNAs as biomarkers and the current obstacles in the exosome isolation technology, shed light to the future development of this technology.     

外泌体在免疫调控及肿瘤发生中的功能

已知细胞间的信息交流不仅可以通过直接接触,或释放信号分子等方式,同时还存在另一种细胞通讯方式即释放外泌体。外泌体是由细胞分泌,直径为30～100 nm的囊泡结构。外泌体含有蛋白质、脂质、mRNAs和miRNAs等成分,并且能够靶向运输到其他细胞或组织中,从而在细胞间的信息交流、物质传递方面发挥重要作用。本文对外泌体的基本特征、形成过程、功能以及在疾病诊断与治疗中的应用等方面进行简要综述,重点介绍外泌体在免疫调控和肿瘤发生方面的功能。外泌体作为一种广泛存在的亚细胞成分,虽然体积小,组成成分简单,然而,其复杂功能具有重要的研究价值。对外泌体功能的深入了解将为肿瘤等疾病的预防和治疗提供更多的诊断标志物、疫苗以及治疗思路与手段。     

Identification of metastasis-associated exoDEPs in colorectal cancer using label-free proteomics

Exosomes are secreted nanovesicles consisting of biochemical molecules, including proteins, RNAs, lipids, and metabolites that play a prominent role in tumor progression. In this study, we performed a label-free proteomic analysis of exosomes from a pair of homologous human colorectal cancer cell line with different metastatic abilities. A total of 115 exoDEPs were identified, with 31 proteins upregulated and 84 proteins downregulated in SW620 exosome. We also detected 30 proteins expressed only in SW620 exosomes and 60 proteins expressed only in SW480 exosomes. Bioinformatics analysis enriched the components and pathways associated with the extracellular matrix, cytoskeleton-related pathways, and immune system changes of colorectal cancer (CRC). Cellular function experiments confirmed the role of SW620 exosomes in promoting the proliferation, migration, and invasion of SW480 cells. Further verifications were performed on six upregulated exoDEPs (FGFBP1, SIPA1, THBS1, TGFBI, COL6A1, and RPL10), three downregulated exoDEPs (SLC2A3, MYO1D, and RBP1), and three exoDEPs (SMOC2, GLG1, and CEMIP) expressed only in SW620 by WB and IHC. This study provides a complete and novel basis for exploring new drug targets to inhibit the invasion and metastasis of CRC.     

The potential role of exosomes derived from ovarian cancer cells for diagnostic and therapeutic approaches

Most patients with ovarian cancer (OC) are diagnosed at the advanced stages due to the absence of appropriate early diagnostic markers. Thus, OC is a gynecological disease with a low-survival rate. Exosomes are extracellular vesicles that are widely being considered as mediators for the noninvasive diagnosis of OC. Exosomes are expected to aid in the effective diagnosis of OC because they carry components, such as RNAs, proteins, and lipids, the compositions of which vary depending on the pathological characteristics of the patient. In this review, we document the methods that have been developed to detect exosomes and their components in OC. We also assess the potential biomarkers contained in exosomes that could be clinically useful, such as proteins, microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and phospholipids. Moreover, we described the role played by exosomes in the tumor microenvironment and in OC angiogenesis, migration, and tumor growth. Various types of cells in the tumor microenvironment, including macrophages, fibroblasts, and mesenchymal stem cells (MSCs), interact directly with exosomes and promote or inhibit the progression of OC. Therefore, we summarize the studies that have suggested a therapeutic approach to OC using exosomes. Collectively, understanding the mechanism of exosome-based OC progression would broaden our knowledge regarding the diagnosis and therapy of OC.     

Exosomes in carcinogenesis: molecular palkis carry signals for the regulation of cancer progression and metastasis

Exosomes, which act as biological cargo vessels, are cell-released, phospholipid-enclosed vesicles. In eukaryotic cells, exosomes carry and exchange biological materials or signals for the benefit or detriment to the cells. Thereby, we consider exosomes to be molecular Palkis (carriers). Although exosomes are currently one of the most popularly researched cellular entities, they have remained largely enigmatic and warrant continued investigation into their structure and functions. These membraned vesicles are between 30 and 150 nm in diameter and are actively secreted by all cell types. While initially considered cellular “trash bags,” recent years have revealed exosomes to be dynamic and multi-functional vesicles that may play a crucial role in cancer development, progression and metastasis. Thereby, they have the potential to be used in development of therapeutic modalities for cancer and other diseases. As more research studies emerge, it’s becoming evident that exosomes are released by cells with a purpose and are representatives of certain cell types and disease conditions. Hence, they may also be used as biomarkers for the detection of cancer initiation, progression and organotropic metastatic growth of cancer cells. This review will focus on the recent developments achieved in identifying the role of exosomes in cancer development and progression as well as therapeutic implications. The review will also discuss the pitfalls of methodologies used for the extraction of exosomes.     

Tumor-derived exosomes: Potential biomarkers and therapeutic target in the treatment of colorectal cancer

Colorectal cancer (CRC) is the third most common cause of cancer-related death in men and women in many countries. Early detection of CRC helps to prevent the advanced stages of the disease, and may thereby improve the survival of these patients. A noninvasive test with high specificity and sensitivity is required for this. Exosomes are lipid bilayer membrane nanovesicles that are released into most body fluids and especially in the microenvironment of cancer. They carry various proteins, lipids, and nucleic materials such as DNA, RNA, messenger RNA (mRNA), and microRNA (miRNA), and may also alter the function of target cells. In this review, we aimed to describe the biogenesis, composition, function, and the role of tumor-derived exosomes in cancer progression. Moreover, their applications in tumor diagnosis and treatment are described, with a particular focus on CRC.     

Circular RNA in colorectal cancer

Circular RNA (circRNA) is a highly abundant type of single-stranded non-coding RNA. Novel research has discovered many roles of circRNA in colorectal cancer (CRC) including proliferation, metastasis and apoptosis. Furthermore, circRNAs also play a role in the development of drug resistance and have unique associations with tumour size, staging and overall survival in CRC that lend circRNAs the potential to serve as diagnostic and prognostic biomarkers. Among cancers worldwide, CRC ranks second in mortality and third in incidence. In order to have a better understanding of the influence of circRNA on CRC development and progression, this review summarizes the role of specific circRNAs in CRC and evaluates their potential value as therapeutic targets and biomarkers for CRC. We aim to provide insight in the development of therapy and clinical decision-making.     

外泌体miRNA生物标志物在肝癌中的研究进展*

外泌体广泛存在于多种体液中,携带有大量活性物质,如mRNA、miRNA、蛋白和脂质等。其中的miRNA是一类短非编码RNA,在转录后水平调节基因的表达,广泛参与个体生长发育等各生命活动。外泌体miRNA有多种生物学功能,在肿瘤的发生发展、侵袭转移、机体耐药及免疫调控等多方面发挥着重要作用。目前的研究表明,无论是作为肿瘤早筛早诊和预后评估标志物还是用于肿瘤治疗,外泌体miRNA都有很好的应用前景。本文就近年来外泌体miRNA在肝癌中的研究进展和临床应用进行综述。     

Tumor exosome promotes Th17 cell differentiation by transmitting the lncRNA CRNDE-h in colorectal cancer

The T helper 17 (Th17) cells in tumor microenvironment play an important role in colorectal cancer (CRC) progression. This study investigated the mechanism of Th17 cell differentiation in CRC with a focus on the role of tumor exosome-transmitted long noncoding RNA (lncRNA). Exosomes were isolated from the CRC cells and serum of CRC patients. The role and mechanism of the lncRNA CRNDE-h transmitted by CRC exosomes in Th17 cell differentiation were assessed by using various molecular biological methods. The serum exosomal CRNDE-h level was positively correlated with the proportion of Th17 cells in the tumor-infiltrating T cells in CRC patients. CRC exosomes contained abundant CRNDE-h and transmitted them to CD4⁺ T cells to increase the Th17 cell proportion, RORγt expression, and IL-17 promoter activity. The underlying mechanism is that, CRNDE-h bound to the PPXY motif of RORγt and impeded the ubiquitination and degradation of RORγt by inhibiting its binding with the E3 ubiquitin ligase Itch. The in vivo experiments confirmed that the targeted silence of CRNDE-h in CD4⁺ T cells attenuated the CRC tumor growth in mice. The present findings demonstrated that the tumor exosome transmitted CRNDE-h promoted Th17 cell differentiation by inhibiting the Itch-mediated ubiquitination and degradation of RORγt in CRC, expanding our understanding of Th17 cell differentiation in CRC.Subject terms: Cancer, Cell biology     

Circulating Exosomal microRNAs as Biomarkers of Colon Cancer

Purpose

Exosomal microRNAs (miRNAs) have been attracting major interest as potential diagnostic biomarkers of cancer. The aim of this study was to characterize the miRNA profiles of serum exosomes and to identify those that are altered in colorectal cancer (CRC). To evaluate their use as diagnostic biomarkers, the relationship between specific exosomal miRNA levels and pathological changes of patients, including disease stage and tumor resection, was examined.

Experimental Design

Microarray analyses of miRNAs in exosome-enriched fractions of serum samples from 88 primary CRC patients and 11 healthy controls were performed. The expression levels of miRNAs in the culture medium of five colon cancer cell lines were also compared with those in the culture medium of a normal colon-derived cell line. The expression profiles of miRNAs that were differentially expressed between CRC and control sample sets were verified using 29 paired samples from post-tumor resection patients. The sensitivities of selected miRNAs as biomarkers of CRC were evaluated and compared with those of known tumor markers (CA19-9 and CEA) using a receiver operating characteristic analysis. The expression levels of selected miRNAs were also validated by quantitative real-time RT-PCR analyses of an independent set of 13 CRC patients.

Results

The serum exosomal levels of seven miRNAs (let-7a, miR-1229, miR-1246, miR-150, miR-21, miR-223, and miR-23a) were significantly higher in primary CRC patients, even those with early stage disease, than in healthy controls, and were significantly down-regulated after surgical resection of tumors. These miRNAs were also secreted at significantly higher levels by colon cancer cell lines than by a normal colon-derived cell line. The high sensitivities of the seven selected exosomal miRNAs were confirmed by a receiver operating characteristic analysis.

Conclusion

Exosomal miRNA signatures appear to mirror pathological changes of CRC patients and several miRNAs are promising biomarkers for non-invasive diagnosis of the disease.     

Proteomic and cytokine plasma biomarkers for predicting progression from colorectal adenoma to carcinoma in human patients

In the present study, we screened proteomic and cytokine biomarkers between patients with adenomatous polyps and colorectal cancer (CRC) in order to improve our understanding of the molecular mechanisms behind turmorigenesis and tumor progression in CRC. To this end, we performed comparative proteomic analysis of plasma proteins using a combination of 2DE and MS as well as profiled differentially regulated cytokines and chemokines by multiplex bead analysis. Proteomic analysis identified 11 upregulated and 13 downregulated plasma proteins showing significantly different regulation patterns with diagnostic potential for predicting progression from adenoma to carcinoma. Some of these proteins have not previously been implicated in CRC, including upregulated leucine‐rich α‐2‐glycoprotein, hemoglobin subunit β, Ig α‐2 chain C region, and complement factor B as well as downregulated afamin, zinc‐α‐2‐glycoprotein, vitronectin, and α‐1‐antichymotrypsin. In addition, plasma levels of three cytokines/chemokines, including interleukin‐8, interferon gamma‐induced protein 10, and tumor necrosis factor α, were remarkably elevated in patients with CRC compared to those with adenomatous polyps. Although further clinical validation is required, these proteins and cytokines can be established as novel biomarkers for CRC and/or its progression from colon adenoma.     

Downregulation of exosome-encapsulated miR-548c-5p is associated with poor prognosis in colorectal cancer

The role of circulating exosomal microRNAs (miRNAs) in colorectal cancer (CRC) has drawn more and more attention during the past few years. Previously, we have identified several specific miRNAs in serum exosomes as potential CRC biomarkers. However, little is known about the association between exosome-encapsulated miR-548c-5p and outcomes of patients with CRC. In the current study, the expression of serum exosomal miR-548c-5p was investigated by quantitative real-time polymerase chain reaction. Its correlation with CRC prognosis was estimated by Kaplan-Meier survival and log-rank tests. Cox regression analysis based on uni- and multivariate analyses was performed to estimate the relationship of exosome-encapsulated miR-548c-5p with the clinicopathological factors of patients with CRC. Reduced levels of serum exosomal miR-548c-5p were more significant in CRC patients with liver metastasis and at later TNM stage (III/IV tumor stages). Serum exosomal miR-548c-5p could inhibit the proliferation of CRC cells, while the precise molecular mechanisms warranted further elucidation. In addition, decreased levels of serum exosomal miR-548c-5p were independently associated with shorter overall survival in CRC adjusted by age, sex, tumor grade vascular infiltration, TNM stage (III/IV tumor stages) and metastasis (hazard ratio = 3.40, 95% confidence interval 1.02-11.27; P = 0.046). The downregulation of exosomal miR-548c-5p in serum predicts poor prognosis in patients with CRC. Exosomal miR-548c-5p may be a critical biomarker for CRC diagnosis and prognosis.