Exosomal microRNAs in colorectal cancer: Overcoming barriers of the metastatic cascade (Review)

Harnessing exosomes in theranostic applications: advancements and insights in gastrointestinal cancer research

Exosomes are small extracellular vesicles (30-150 nm) that are formed by endocytosis containing complex RNA as well as protein structures and are vital in intercellular communication and can be used in gene therapy and drug delivery. According to the cell sources of origin and the environmental conditions they are exposed to, these nanovesicles are very heterogeneous and dynamic in terms of content (cargo), size and membrane composition. Exosomes are released under physiological and pathological conditions and influence the pathogenesis of cancers through various mechanisms, including angiogenesis, metastasis, immune dysregulation, drug resistance, and tumor growth/development. Gastrointestinal cancer is one of the deadliest types of cancer in humans and can involve organs e.g., the esophagus and stomach, or others such as the liver, pancreas, small intestine, and colon. Early diagnosis is very important in this field because the overall survival of patients is low due to diagnosis in late stages and recurrence. Also, various therapeutic strategies have failed and there is an unmet need for the new therapeutic agents. Exosomes can become promising candidates in gastrointestinal cancers as biomarkers and therapeutic agents due to their lower immunity and passing the main physiological barriers. In this work, we provide a general overview of exosomes, their biogenesis and biological functions. In addition, we discuss the potential of exosomes to serve as biomarkers, agents in cancer treatment, drug delivery systems, and effective vaccines in immunotherapy, with an emphasis on gastrointestinal cancers.

miRNA as a Biomarker for the Early Detection of Colorectal Cancer

MicroRNAs (miRNAs) are short, non-coding RNA segments that can be detected in a variety of clinical samples, including serum, stool, and urine. While miRNAs were initially known for their effect on post-translational gene expression, the last decade of research has shown them to be promising biomarkers for the detection of many types of cancer. This paper explores the use of miRNA detection as a tool for colorectal cancer (CRC) screening. We discuss the current state of miRNA detection, compare it to the existing CRC screening tools, and highlight the advantages and drawbacks of this approach from a clinical and logistical perspective. Our research finds that miRNA-based tests for CRC show great potential, but that widespread clinical adoption will be conditional on future research overcoming key hurdles.

YB-1 Targeted by miR-509-3-5p Affects Migration and Invasion of Triple‑Negative Breast Cancer by Regulating Cellular Epithelial‑Mesenchymal Transition

The epithelial-mesenchymal transition (EMT) process is closely linked to metastasis of breast cancer. This article elucidates the role of Y-box binding protein-1 (YB-1) on the migration and invasion of triple-negative breast cancer (TNBC) cells by regulating EMT, and the related mechanism. The expression data of YB-1 and miR-509-3-5p in TNBC samples and normal samples were downloaded from the GEO database. The proliferation, migration, invasion, and EMT of TNBC cells were detected by CCK-8 assay, colony formation assay, wound-healing assay, transwell assay, and immunoblotting analyses. The targeted binding of YB-1 and miR-509-3-5p was validated by luciferase reporter experiment. A xenograft mouse model was constructed to investigate the influence of the miR-509-3-5p/YB-1 axis on TNBC tumor growth in vivo. YB-1 was overexpressed, while miR-509-3-5p was underexpressed in TNBC tumor tissues and various cell lines. Silencing YB-1 depressed cell viability, proliferation, motility, and EMT in vitro, and miR-509-3-5p upregulation exerted the same effects. YB-1 was targeted by miR-509-3-5p. The suppressive effects on the phenotypes of TNBC cells caused by overexpressed miR-509-3-5p were attenuated by YB-1 upregulation. In addition, miR-509-3-5p overexpression restrained TNBC tumor growth and downregulated the YB-1-mediated EMT process in vivo. YB-1 targeted by miR-509-3-5p affects motility of TNBC cells by regulating cellular EMT.

The role of exo-miRNA in diagnosis and treatment of cancers, focusing on effective miRNAs in colorectal cancer

Small extracellular (EV) particles known as exosomes are released by a variety of cell types, including immune system cells, stem cells, and tumor cells. They are regarded as a subgroup of EVs and have a diameter that ranges from 30 to 150 nm. Proteins, lipids, nucleic acids (including RNA and DNA), and different bioactive compounds are among the wide range of biomolecules that make up the cargo of exosomes. Exosomes are crucial for intercellular communication because they let cells share information and signaling chemicals. They are involved in various physiological and pathological processes, including immune responses, tissue regeneration, cancer progression, and neurodegenerative diseases. In conclusion, it is essential to continue research into exosome-based cancer medicines to advance understanding, improve treatment plans, create personalized tactics, ensure safety, and speed up clinical translation.

Research progress of exosomes in the angiogenesis of digestive system tumour

Malignant tumours of the digestive system cover a wide range of diseases that affect the health of people to a large extent. Angiogenesis is indispensable in the development, and metastasis of tumours, mainly in two ways: occupation or formation. Vessels can provide nutrients, oxygen, and growth factors for tumours to encourage growth and metastasis, so cancer progression depends on simultaneous angiogenesis. Recently, exosomes have been proven to participate in the angiogenesis of tumours. They influence angiogenesis by binding to tyrosine kinase receptors (VEGFR)-1, VEGFR-2, and VEGFR-3 with different affinities, regulating Yap-VEGF pathway, Akt pathway or other signaling pathway. Additionally, exosomes are potential therapeutic vectors that can deliver many types of cargoes to different cells. In this review, we summarize the roles of exosomes in the angiogenesis of digestive system tumours and highlight the clinical application prospects, directly used as targers or delivery vehicles, in antiangiogenic therapy.

Exosome-derived miR-372-5p promotes stemness and metastatic ability of CRC cells by inducing macrophage polarization

Colorectal cancer (CRC) is the most common malignancy in the digestive system, and tumor metastasis is the main cause of death in clinical patients with CRC. It has been shown that exosomes promote phenotypic changes in macrophages and tumor metastasis in the CRC tumor microenvironment. In this study, we used miRNA-seq technology to screen out the highly expressed miR-372-5p among the miRNAs differentially expressed in plasma exosomes of clinical CRC patients. It was found that miR-372-5p highly expressed in HCT116 exosomes could be phagocytosed by macrophages and promote their polarization into M2 macrophages by regulating the PTEN/AKT pathway. Meanwhile, co-culture of CRC cells with conditioned medium (CM) of macrophages enhanced the EMT, stemness and metastasis of CRC cells. Mechanistically, CRC cells exosome-derived miR-372-5p induced polarized M2 macrophages to secrete chemokine C-X-C-Motif Ligand 12 (CXCL12), which activated the WNT/β-catenin pathway to promote the EMT, stemness and metastatic ability of CRC cells. In summary, this study elucidated the molecular mechanism of exosomal miR-372-5p promoting metastasis and stemness in CRC, which may provide new therapeutic targets for CRC metastasis and prognosis assessment.

Regulatory role of exosomes in colorectal cancer progression and potential as biomarkers

Colorectal cancer (CRC) remains an enormous challenge to human health worldwide. Unfortunately, the mechanism underlying CRC progression is not well understood. Mounting evidence has confirmed that exosomes play a vital role in CRC progression, which has attracted extensive attention among researchers. In addition to acting as messengers between CRC cells, exosomes also participate in the CRC immunomodulatory process and reshape immune function. As stable message carriers and liquid biopsy option under development, exosomes are promising biomarkers in the diagnosis or treatment of CRC. In this review we have described and analyzed the biogenesis and release of exosomes and current research on the role of exosomes in immune regulation and metastasis of CRC. Moreover, we have discussed candidate exosomal molecules as potential biomarkers to diagnose CRC, predict CRC progression, or determine CRC chemoresistance, and described the significance of exosomes in the immunotherapy of CRC. This review provides insight to further understand the role of exosomes in CRC progression and identify valuable biomarkers that facilitate the clinical management of CRC patients.

Circulating exosomal microRNAs as potential prognostic biomarkers in gastrointestinal cancers: a systematic review and meta-analysis

BACKGROUND

Recent reports suggested that circulating exosomal microRNAs (exomiRs) may serve as non-invasive prediction biomarkers in gastrointestinal (GI) cancers, yet their clinicopathological and prognostic values need to be more clarified. Hence, the present meta-analysis was aimed to quantitatively assess the evidence regarding the association between circulating exomiRs and prognosis in GI cancer patients.

METHODS

A comprehensive search was carried out in prominent literature databases, including PubMed, ISI Web of Science, Scopus, and Embase. Odds ratios (ORs) or hazard ratios (HRs) with 95% confidence intervals (CIs) were gathered to evaluate the strength of the association. The quality assessment was investigated through the Newcastle-Ottawa Scale (NOS) and publication bias via Eggers' test and funnel plots.

RESULTS

A total of 47 studies, comprising of 4881 patients, were considered eligible for this meta-analysis. Both up-regulated and down-regulated circulating exomiRs are significantly associated with differentiation (HR = 1.353, P = 0.015; HR = 1.504, P = 0.016), TNM stage (HR = 2.058, P < 0.001; HR = 2.745, P < 0.001), lymph node metastasis (HR = 1.527, P = 0.004; HR = 2.009, P = 0.002), distant metastasis (HR = 2.006, P < 0.001; HR = 2.799, P = 0.002), worse overall survival (OS) (HR = 2.053, P < 0.001; HR = 1.789, P = 0.001) and poorer disease/relapse/progression-free survival (DFS/RFS/PFS) (HR = 2.086, P < 0.001; HR = 1.607, P = 0.001) in GI cancer patients, respectively. In addition, subgroup analyses based on seven subcategories indicated the robustness of the association. The majority of findings were lack of publication bias except for the association between up-regulated exomiRs and OS or DFS/RFS/PFS and for the down-regulated exomiRs and TNM stage.

CONCLUSION

This study supports that up- and down-regulated circulating exomiRs are associated with poorer survival outcomes and could be served as potential prognostic biomarkers in GI cancers. Given the limitations of the current findings, such as significant heterogeneity, more investigations are needed to fully clarify the exomiRs prognostic role.

Downregulation of exosomal miR-7-5p promotes breast cancer migration and invasion by targeting RYK and participating in the atypical WNT signalling pathway

Background

Current studies show that exosomal miRNAs become an important factor in cancer metastasis. Among the many miRNA studies, miR-7-5p has not been thoroughly investigated in breast cancer metastasis.

Methods

Bioinformatic screening was performed using extant data from the GEO database, and miR-7-5p expression levels in breast cancer cell lines and exosomes were further examined using real-time quantitative PCR (qRT-PCR). The extracted exosomes were characterised by transmission electron microscopy (TEM), particle size analysis and marker protein determination. Cell migration and invasion were then examined using wound healing assays and Transwell assays, respectively. Correlation between miR-7-5p and receptor-like tyrosine kinase (RYK) was analysed by luciferase reporter. The effect of miR-7-5p against RYK-related downstream factors was verified using western blot assays.

Results

In this study, we found that the expression of miR-7-5p was significantly different in exosomes secreted from breast cancer cell lines with different high and low invasiveness. Further experiments revealed that miR-7-5p has an important role in inhibiting the migration and invasion of breast cancer. In terms of mechanism of action, miR-7-5p was found to target the RYK, leading to its reduced expression, which in turn caused a reduction in the phosphorylation level of the downstream factor JNK. Reduced levels of phosphorylated JNK factors lead to reduced levels of phosphorylation of c-Jun protein, which in turn leads to increased expression of EMT transcription factors, thereby inhibiting the epithelial–mesenchymal transition (EMT) process to suppress the invasion of breast cancer.

Conclusion

Thus, we demonstrated that exosomes loaded with high levels of miR-7-5p emitted from less aggressive breast cancers can participate in the atypical WNT pathway by targeting the RYK gene and thus inhibit breast cancer metastasis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11658-022-00393-x.

Molecular Docking and Intracellular Translocation of Extracellular Vesicles for Efficient Drug Delivery

Extracellular vesicles (EVs), including exosomes, mediate intercellular communication by delivering their contents, such as nucleic acids, proteins, and lipids, to distant target cells. EVs play a role in the progression of several diseases. In particular, programmed death-ligand 1 (PD-L1) levels in exosomes are associated with cancer progression. Furthermore, exosomes are being used for new drug-delivery systems by modifying their membrane peptides to promote their intracellular transduction via micropinocytosis. In this review, we aim to show that an efficient drug-delivery system and a useful therapeutic strategy can be established by controlling the molecular docking and intracellular translocation of exosomes. We summarise the mechanisms of molecular docking of exosomes, the biological effects of exosomes transmitted into target cells, and the current state of exosomes as drug delivery systems.

Identification of a Five-MiRNA Expression Assay to Aid Colorectal Cancer Diagnosis

Introduction: One-third of colorectal cancer (CRC) patients present with advanced disease, and establishing control remains a challenge. Identifying novel biomarkers to facilitate earlier diagnosis is imperative in enhancing oncological outcomes. We aimed to create miRNA oncogenic signature to aid CRC diagnosis. Methods: Tumour and tumour-associated normal (TAN) were extracted from 74 patients during surgery for CRC. RNA was isolated and target miRNAs were quantified using real-time reverse transcriptase polymerase chain reaction. Regression analyses were performed in order to identify miRNA targets capable of differentiating CRC from TAN and compared with two endogenous controls (miR-16 and miR-345) in each sample. Areas under the curve (AUCs) in Receiver Operating Characteristic (ROC) analyses were determined. Results: MiR-21 (β-coefficient:3.661, SE:1.720, p = 0.033), miR-31 (β-coefficient:2.783, SE:0.918, p = 0.002), and miR-150 (β-coefficient:−4.404, SE:0.526, p = 0.004) expression profiles differentiated CRC from TAN. In multivariable analyses, increased miR-31 (β-coefficient:2.431, SE:0.715, p < 0.001) and reduced miR-150 (β-coefficient:−4.620, SE:1.319, p < 0.001) independently differentiated CRC from TAN. The highest AUC generated for miR-21, miR-31, and miR-150 in an oncogenic expression assay was 83.0% (95%CI: 61.7–100.0, p < 0.001). In the circulation of 34 independent CRC patients and 5 controls, the mean expression of miR-21 (p = 0.001), miR-31 (p = 0.001), and miR-150 (p < 0.001) differentiated CRC from controls; however, the median expression of miR-21 (p = 0.476), miR-31 (p = 0.933), and miR-150 (p = 0.148) failed to differentiate these groups. Conclusion: This study identified a five-miRNA signature capable of distinguishing CRC from normal tissues with a high diagnostic test accuracy. Further experimentation with this signature is required to elucidate its diagnostic relevance in the circulation of CRC patients.

MicroRNA-4463 facilitates the development of colon cancer by suppression of the expression of PPP1R12B

PURPOSE

In the present work, we investigated the expression pattern of miR-4463 in the non-metastasis and metastasis colorectal cancer (CRC) patients and its regulation axis.

METHODS

RT-qPCR assay was performed to assess miR-4463 expression in the serum and tissues of patients with non-metastasis and metastasis, and in the CRC cell lines. MTT assay, colony formation assay, transwell assay, and flow cytometry assay were used to examine the role of miR-4463 in CRC cell viability, proliferation, and migration. Bioinformatic analysis was used to identify the potential target gene of miR-4463, and the targeting relationship between miR-4463 and PPP1R12B was verified in vitro using dual luciferase assay. Western blotting assay was used to determine the protein level of the target gene PPP1R12B in CRC cells under the transfections of miR-4463 mimic, inhibitor and vectors overexpressing PPP1R12B.

RESULTS

miR-4463 was markedly increased in the non-metastasis CRC tissues, and increased even higher in the metastasis CRC tissues, while miR-4463 expression had no significant difference in serum from non-metastasis and metastasis CRC samples. Besides, miR-4463 was upregulated in CRC cell lines. Functionally, miR-4463 promoted CRC cell proliferation, migration, and inhibiting cell apoptosis. Further analysis revealed that the miR-4463/PPP1R12B axis was responsible for the role of this miRNA.

CONCLUSION

We reported the roles of miR-4463 in CRC proliferation and migration, supporting that miR-4463 could be a potential predictive diagnostic marker for colon cancer.

Exosomal miRNAs as a Promising Source of Biomarkers in Colorectal Cancer Progression

Colorectal cancer (CRC) is the third most common type of cancer worldwide amongst males and females. CRC treatment is multidisciplinary, often including surgery, chemotherapy, and radiotherapy. Early diagnosis of CRC can lead to treatment initiation at an earlier stage. Blood biomarkers are currently used to detect CRC, but because of their low sensitivity and specificity, they are considered inadequate diagnostic tools and are used mainly for following up patients for recurrence. It is necessary to detect novel, noninvasive, specific, and sensitive biomarkers for the screening and diagnosis of CRC at earlier stages. The tumor microenvironment (TME) has an essential role in tumorigenesis; for example, extracellular vesicles (EVs) such as exosomes can play a crucial role in communication between cancer cells and different components of TME, thereby inducing tumor progression. The importance of miRNAs that are sorted into exosomes has recently attracted scientists’ attention. Some unique sequences of miRNAs are favorably packaged into exosomes, and it has been illustrated that particular miRNAs can be directed into exosomes by special mechanisms that occur inside the cells. This review illustrates and discusses the sorted and transported exosomal miRNAs in the CRC microenvironment and their impact on CRC progression as well as their potential use as biomarkers.

Tumor Microenvironment Shapes Colorectal Cancer Progression, Metastasis, and Treatment Responses

Colorectal cancer (CRC) is one of the most devastating diseases that accounts for numerous deaths worldwide. Tumor cell-autonomous pathways, such as the oncogenic signaling activation, significantly contribute to CRC progression and metastasis. Recent accumulating evidence suggests that the CRC microenvironment also profoundly promotes or represses this process. As the roles of the tumor microenvironment (TME) in CRC progression and metastasis is gradually uncovered, the importance of these non-cell-autonomous signaling pathways is appreciated. However, we are still at the beginning of this TME function exploring process. In this review, we summarize the current understanding of the TME in CRC progression and metastasis by focusing on the gut microbiota and host cellular and non-cellular components. We also briefly discuss TME-remodeling therapies in CRC.

MiR-29a regulates cardiomyocyte apoptosis by targeting Bak1 in diabetic cardiomyopathy

This study sought to investigate the association between microRNA-29a (miR-29a) and cardiomyocyte apoptosis in diabetic cardiomyopathy (DCM). DCM rat model was established by treating rats with streptozotocin (STZ), followed by injection of NC or miR-29a-3p mimics into the myocardium of rats. High glucose (HG)-treated H9c2 cells were transfected with NC and miR-29a-3p mimics. DCM rats presented elevated levels of blood glucose, HbA1c, and blood pressure and urine output and decreased body weight and cardiac contractile function after modeling. MiR-29a was lowly expressed in STZ-treated rats and HG-treated H9c2 cells. Upregulation of miR-29a improved cardiac structure and function and attenuated, alleviated myocardial histological abnormalities and fibrosis, and lowered cardiomyocyte apoptosis in DCM rats. Meanwhile, HG promoted H9c2 cell apoptosis, while miR-29a overexpression attenuated the function of HG. Compared with control group, the protein expression of Bax, cleaved-caspase3 and Bak1 in DCM and HG group were significantly upregulated, and the expression of Bcl-2 and Mcl-1 were downregulated, while miR-29a overexpression exerted opposite effect. Bioinformatics prediction method and western blot revealed that miR-29a directly targeted Bak1 and downregulated Bak1 expression. Overall, miR-29a regulated STZ- and HG-induced cardiomyocyte apoptosis by targeting Bak1, providing a novel understanding of the pathogenesis of DCM.

Importance of Extracellular Vesicle Derived RNAs as Critical Colorectal Cancer Biomarkers

Colorectal cancer typically begins from a nonmalignant polyp formation in the large intestine that, over time, develops into colorectal cancer. The growth of benign polyps can be checked if detected in the early stages of the disease. Doctors usually recommend colonoscopy to average and high-risk individuals for colorectal cancer screening. Elevated carcinoembryonic antigen (CEA) is a broadly used biomarker for colorectal cancer. The genetic and epigenetic alteration of genes such as p53, BRAF, APC, and PIK3CA is also correlated with colorectal cancer in various clinical studies. In general, tissue biopsy is most frequently used for colorectal cancer diagnosis, but the whole tumor heterogeneity cannot be accessed by this technique. Furthermore, such a highly invasive technique is not suitable for repeated testing. Recently, extracellular vesicles (EVs), lipid bilayer enclosed sacs secreted from colorectal cancer cells, are emerging as a diagnostic tool for colon cancer detection. The major advantages of using EVs for colon cancer diagnosis are (i) EVs can be isolated in a noninvasive manner from the body fluid and (ii) EV incorporated cargoes (mostly RNAs) reveal various aspects of colorectal cancer. EV-RNAs are also implicated in tumor invasion and influence the immune system for the further spread of tumors. However, due to the lack of standardized EV detection strategies, diagnostic applicability is limited. Herein, we review the recent literature on the pathobiological dependence of colorectal cancer on EV-RNAs. Further, we present the advantages of identification and characterization of EV-RNAs to explore the connection between differential expression of extracellular vesicle incorporated RNAs and colorectal cancer. How this approach may potentially translate into point of care colorectal cancer diagnostics is also discussed.

The Incredible Potential of Exosomes as Biomarkers in the Diagnosis of Colorectal Cancer

Colorectal cancer (CRC) is common cancer that is one of the leading causes of cancerrelated deaths around the world. The creation of new biomarkers for this disease is an important public health strategy for lowering the disease's mortality rate. According to new research, exosomes may be important sources of biomarkers in CRC. Exosomes are nanometer-sized membrane vesicles (30-200 nm) secreted by normal and cancer cells that transport RNA and proteins between cells and are thought to help with intercellular communication. Exosomes have been linked to CRC initiation and progression, and some differentially expressed RNAs and proteins in exosomes have been identified as potential cancer detection candidates. As a result, studying the relationship between exosomes and CRC may aid in the development of new biomarkers for the disease. This article discusses the importance of exosomes as biomarkers in the diagnosis of CRC, as well as their use in the treatment of CRC metastasis, chemoresistance, and recrudescence. The benefits and drawbacks of using exosomes as tumour markers are also discussed.