Glioblastoma Stem Cell-Derived Exosomes Enhance Stemness and Tumorigenicity of Glioma Cells by Transferring Notch1 Protein

Therapeutic combinations of exosomes alongside cancer stem cells (CSCs) and of CSC-derived exosomes (CSCEXs) in cancer therapy

Exosomes which are membrane vesicles released by cells have gained significant interest in the field of cancer therapy as a novel means of intercellular communication. Their role in immune activation and their pathophysiological functions in cancer therapy have been recognized. Exosomes carry diverse bioactive components including proteins, mRNA, microRNAs, and bioactive lipids. These molecules have therapeutic potential in promoting tissue regeneration, supporting stem cell activity, preventing cell death, modulating immune responses, and promoting the growth of new blood vessels. However, the precise roles of exosomes derived from mesenchymal stem cells (MSCs) in the treatment of various cancers are still not fully understood. Consequently, cancer stem cells (CSCs) can self-renew and differentiate into various cell types. Understanding the mechanisms that sustain their persistence is crucial for developing effective therapies. Exosomes have recently gained interest as vehicles for intercellular communication between CSCs and non-CSCs, influencing cancer progression and the microenvironment. Research is ongoing on the utilization of exosomes derived from cancer stem cells (CSC-Exosome) for cancer treatment. The composition of extracellular vesicles is influenced by the specific type and condition of the cells from which they are secreted. Circulating exosomes contain stable RNA molecules such as mRNAs, microRNAs, and long non-coding RNAs (lncRNAs). In this review, we will explore the significance of exosomes and their diverse cellular combinations in the context of cancer therapy.

Exosomal misfolded proteins released by cancer stem cells: dual functions in balancing protein homeostasis and orchestrating tumor progression

Cancer stem cells (CSCs), the master regulators of tumor heterogeneity and progression, exert profound influence on cancer metastasis, via various secretory vesicles. Emerging from CSCs, the exosomes serve as pivotal mediators of intercellular communication within the tumor microenvironment, modulating invasion, angiogenesis, and immune responses. Moreover, CSC-derived exosomes play a central role in sculpting a dynamic landscape, contributing to the malignant phenotype. Amidst several exosomal cargoes, misfolded proteins have recently gained attention for their dual functions in maintaining protein homeostasis and promoting tumor progression. Disrupting these communication pathways could potentially prevent the maintenance and expansion of CSCs, overcome treatment resistance, and inhibit the supportive environment created by the tumor microenvironment, thereby improving the effectiveness of cancer therapies and reducing the risk of tumor recurrence and metastasis. Additionally, exosomes have also shown potential therapeutic applications, such as in drug delivery or as biomarkers for cancer diagnosis and prognosis. Therefore, comprehending the biology of exosomes derived from CSCs is a multifaceted area of research with implications in both basic sciences and clinical applications. This review explores the intricate interplay between exosomal misfolded proteins released by CSCs, the potent contributor in tumor heterogeneity, and their impact on cellular processes, shedding light on their role in cancer progression.

Cancer stem cell-derived exosomes in CD8+ T cell exhaustion

Tumor-derived extracellular vesicles (EVs) are one of the most important ways of intercellular communication and signaling. Cancer stem cells (CSCs) secrete EVs to modulate immune checkpoint molecules and evade immune surveillance. Activated CD8+ T cells known as cytotoxic T lymphocytes (CTLs) are the most powerful anti-cancer adaptive cells. Their activity is compromised upon encountering cells and signaling within the tumor microenvironment (TME), resulting in hyporesponsiveness called exhaustion. CSC-derived exosomes express programmed death ligand-1 (PD-L1) and upregulate programmed death-1 (PD-1) on CD8+ T cells to promote their exhaustion. PD-L1 expression on tumor-derived exosomes appears to be induced by CSC-derived exosomes containing transforming growth factor (TGF)-β. Tenascin-C is another constituent of CSC exosomes that acts on mammalian target of rapamycin (mTOR) signaling in T cells. Glycolysis is a metabolic event promoted by the inducing effect of CSC-derived exosomes on hypoxia-inducible factor-1α (HIF-1α). CSC interaction with CD8+ T cells is even more complex as the CSC-derived exosomes contain Notch1 to stimulate stemness in non-tumor cells, and the inducible effect of Notch1 on PD-1 promotes CD8+ T cell exhaustion. CSC exosome targeting has not been extensively studied yet. Advances in the field will open up new therapeutic windows and shape the future of cancer immunotherapy.

Extracellular vesicles and cancer stem cells: a deadly duo in tumor progression

The global incidence of cancer is increasing, with estimates suggesting that there will be 26 million new cases and 17 million deaths per year by 2030. Cancer stem cells (CSCs) and extracellular vesicles (EVs) are key to the resistance and advancement of cancer. They play a crucial role in tumor dynamics and resistance to therapy. CSCs, initially discovered in acute myeloid leukemia, are well-known for their involvement in tumor initiation, progression, and relapse, mostly because of their distinct characteristics, such as resistance to drugs and the ability to self-renew. EVs, which include exosomes, microvesicles, and apoptotic bodies, play a vital role in facilitating communication between cells within the tumor microenvironment (TME). They have a significant impact on cellular behaviors and contribute to genetic and epigenetic changes. This paper analyzes the mutually beneficial association between CSCs and EVs, emphasizing their role in promoting tumor spread and developing resistance mechanisms. This review aims to investigate the interaction between these entities in order to discover new approaches for attacking the complex machinery of cancer cells. It highlights the significance of CSCs and EVs as crucial targets in the advancement of novel cancer treatments, which helps stimulate additional research, promote progress in ideas for cancer treatment, and provide renewed optimism in the effort to reduce the burden of cancer.

Cancer stem cells: advances in knowledge and implications for cancer therapy

Cancer stem cells (CSCs), a small subset of cells in tumors that are characterized by self-renewal and continuous proliferation, lead to tumorigenesis, metastasis, and maintain tumor heterogeneity. Cancer continues to be a significant global disease burden. In the past, surgery, radiotherapy, and chemotherapy were the main cancer treatments. The technology of cancer treatments continues to develop and advance, and the emergence of targeted therapy, and immunotherapy provides more options for patients to a certain extent. However, the limitations of efficacy and treatment resistance are still inevitable. Our review begins with a brief introduction of the historical discoveries, original hypotheses, and pathways that regulate CSCs, such as WNT/β-Catenin, hedgehog, Notch, NF-κB, JAK/STAT, TGF-β, PI3K/AKT, PPAR pathway, and their crosstalk. We focus on the role of CSCs in various therapeutic outcomes and resistance, including how the treatments affect the content of CSCs and the alteration of related molecules, CSCs-mediated therapeutic resistance, and the clinical value of targeting CSCs in patients with refractory, progressed or advanced tumors. In summary, CSCs affect therapeutic efficacy, and the treatment method of targeting CSCs is still difficult to determine. Clarifying regulatory mechanisms and targeting biomarkers of CSCs is currently the mainstream idea.

Extracellular vesicles in glioblastoma: Biomarkers and therapeutic tools

Glioblastoma (GBM) is the most aggressive tumor among the gliomas and intracranial tumors and to date prognosis for GBM patients remains poor, with a median survival typically measured in months to a few years depending on various factors. Although standardized therapies are routinely employed, it is clear that these strategies are unable to cope with heterogeneity and invasiveness of GBM. Furthermore, diagnosis and monitoring of responses to therapies are directly dependent on tissue biopsies or magnetic resonance imaging (MRI) techniques. From this point of view, liquid biopsies are arising as key sources of a variety of biomarkers with the advantage of being easily accessible and monitorable. In this context, extracellular vesicles (EVs), physiologically shed into body fluids by virtually all cells, are gaining increasing interest both as natural carriers of biomarkers and as specific signatures even for GBM. What makes these vesicles particularly attractive is they are also emerging as therapeutical vehicles to treat GBM given their native ability to cross the blood-brain barrier (BBB). Here, we reviewed recent advances on the use of EVs as biomarker for liquid biopsy and nanocarriers for targeted delivery of anticancer drugs in glioblastoma.

Challenges and opportunities for cancer stem cell-targeted immunotherapies include immune checkpoint inhibitor, cancer stem cell-dendritic cell vaccine, chimeric antigen receptor immune cells, and modified exosomes

Cancer stem cells (CSCs) are associated with the tumor microenvironment (TME). CSCs induce tumorigenesis, tumor recurrence and progression, and resistance to standard therapies. Indeed, CSCs pose an increasing challenge to current cancer therapy due to their stemness or self-renewal properties. The molecular and cellular interactions between heterogeneous CSCs and surrounding TME components and tumor-supporting immune cells show synergistic effects toward treatment failure. In the immunosuppressive TME, CSCs express various immunoregulatory proteins, growth factors, metabolites and cytokines, and also produce exosomes, a type of extracellular vesicles, to protect themselves from host immune surveillance. Among these, the identification and application of CSC-derived exosomes could be considered for the development of therapeutic approaches to eliminate CSCs or cancer, in addition to targeting the modulators that remodel the composition of the TME, as reviewed in this study. Here, we introduce the role of CSCs and how their interaction with TME complicates immunotherapies, and then present the CSC-based immunotherapy and the limitation of these therapies. We describe the biology and role of tumor/CSC-derived exosomes that induce immune suppression in the TME, and finally, introduce their potentials for the development of CSC-based targeted immunotherapy in the future.

Extracellular vesicles in glioblastoma: a challenge and an opportunity

Glioblastoma is a highly heterogeneous tumor whose pathophysiological complexities dictate both the diagnosis of disease severity as well as response to therapy. Conventional diagnostic tools and standard treatment regimens have only managed to achieve limited success in the management of patients suspected of glioblastoma. Extracellular vesicles are an emerging liquid biopsy tool that has shown great promise in resolving the limitations presented by the heterogeneous nature of glioblastoma. Here we discuss the contrasting yet interdependent dual role of extracellular vesicles as communication agents that contribute to the progression of glioblastoma by creating a heterogeneous microenvironment and as a liquid biopsy tool providing an opportunity to accurately identify the disease severity and progression.

Harnessing the potential of nanoengineered siRNAs carriers for target responsive glioma therapy: Recent progress and future opportunities

Past scientific testimonials in the field of glioma research, the deadliest tumor among all brain cancer types with the life span of 10-15 months after diagnosis is considered as glioblastoma multiforme (GBM). Even though the availability of treatment options such as chemotherapy, radiotherapy, and surgery, are unable to completely cure GBM due to tumor microenvironment complexity, intrinsic cellular signalling, and genetic mutations which are involved in chemoresistance. The blood-brain barrier is accountable for restricting drugs entry at the tumor location and related biological challenges like endocytic degradation, short systemic circulation, and insufficient cellular penetration lead to tumor aggression and progression. The above stated challenges can be better mitigated by small interfering RNAs (siRNA) by knockdown genes responsible for tumor progression and resistance. However, siRNA encounters with challenges like inefficient cellular transfection, short circulation time, endogenous degradation, and off-target effects. The novel functionalized nanocarrier approach in conjunction with biological and chemical modification offers an intriguing potential to address challenges associated with the naked siRNA and efficiently silence STAT3, coffilin-1, EGFR, VEGF, SMO, MGMT, HAO-1, GPX-4, TfR, LDLR and galectin-1 genes in GBM tumor. This review highlights the nanoengineered siRNA carriers, their recent advancements, future perspectives, and strategies to overcome the systemic siRNA delivery challenges for glioma treatment.

Mechanism of Notch Signaling Pathway in Malignant Progression of Glioblastoma and Targeted Therapy

Glioblastoma multiforme (GBM) is the most aggressive form of glioma and the most common primary tumor of the central nervous system. Despite significant advances in clinical management strategies and diagnostic techniques for GBM in recent years, it remains a fatal disease. The current standard of care includes surgery, radiation, and chemotherapy, but the five-year survival rate for patients is less than 5%. The search for a more precise diagnosis and earlier intervention remains a critical and urgent challenge in clinical practice. The Notch signaling pathway is a critical signaling system that has been extensively studied in the malignant progression of glioblastoma. This highly conserved signaling cascade is central to a variety of biological processes, including growth, proliferation, self-renewal, migration, apoptosis, and metabolism. In GBM, accumulating data suggest that the Notch signaling pathway is hyperactive and contributes to GBM initiation, progression, and treatment resistance. This review summarizes the biological functions and molecular mechanisms of the Notch signaling pathway in GBM, as well as some clinical advances targeting the Notch signaling pathway in cancer and glioblastoma, highlighting its potential as a focus for novel therapeutic strategies.

Exosomes in Glioma: Unraveling Their Roles in Progression, Diagnosis, and Therapy

Gliomas, the most prevalent primary malignant brain tumors, present a challenging prognosis even after undergoing surgery, radiation, and chemotherapy. Exosomes, nano-sized extracellular vesicles secreted by various cells, play a pivotal role in glioma progression and contribute to resistance against chemotherapy and radiotherapy by facilitating the transportation of biological molecules and promoting intercellular communication within the tumor microenvironment. Moreover, exosomes exhibit the remarkable ability to traverse the blood-brain barrier, positioning them as potent carriers for therapeutic delivery. These attributes hold promise for enhancing glioma diagnosis, prognosis, and treatment. Recent years have witnessed significant advancements in exosome research within the realm of tumors. In this article, we primarily focus on elucidating the role of exosomes in glioma development, highlighting the latest breakthroughs in therapeutic and diagnostic approaches, and outlining prospective directions for future research.

Regulation of cancer stem cells and immunotherapy of glioblastoma (Review)

Glioblastoma (GB) is one of the most adverse diagnoses in oncology. Complex current treatment results in a median survival of 15 months. Resistance to treatment is associated with the presence of cancer stem cells (CSCs). The present review aimed to analyze the mechanisms of CSC plasticity, showing the particular role of β-catenin in regulating vital functions of CSCs, and to describe the molecular mechanisms of Wnt-independent increase of β-catenin levels, which is influenced by the local microenvironment of CSCs. The present review also analyzed the reasons for the low effectiveness of using medication in the regulation of CSCs, and proposed the development of immunotherapy scenarios with tumor cell vaccines, containing heterogenous cancer cells able of producing a multidirectional antineoplastic immune response. Additionally, the possibility of managing lymphopenia by transplanting hematopoietic stem cells from a healthy sibling and using clofazimine or other repurposed drugs that reduce β-catenin concentration in CSCs was discussed in the present study.

E3 ubiquitin-ligase RNF138 may regulate p53 protein expression to regulate the self-renewal and tumorigenicity of glioma stem cells

BACKGROUND

Glioblastoma multiforme (GBM), the most malignant tumor of the central nervous system, is characterized by poor survival and high recurrence. Glioma stem cells (GSCs) are key to treating GBM and are regulated by various signaling pathways. Ubiquitination, a post-translational modification, plays an important regulatory role in many biological processes. Ring finger protein 138 (RNF138) is an E3 ubiquitin-protein ligase that is highly expressed in several tumors; however, its role in GBM is unclear. This study investigated whether RNF138 regulates the self-renewal ability of glioma stem GSCs to treat GBM.

MATERIALS AND METHODS

The expression of RNF138 in glioma tissues and its correlation with GSCs were analyzed using bioinformatics. Short hairpin ribonucleic acid (RNA) was designed to downregulate the expression of RNF138 in GSCs, and immunofluorescence, secondary pellet formation, and western blotting were used to detect changes in GSC markers and self-renewal ability. The effects of RNF138 on p53 protein expression were determined by immunofluorescence and western blotting. The effects of RNF138 on the self-renewal and tumorigenic abilities of GSCs were evaluated in vivo.

RESULTS

RNF138 expression was higher in glioma tissues than in normal brain tissues, and was highly expressed in GSCs. RNF138 downregulation significantly decreased the expression of the GSC markers cluster of differentiation 133 (CD133) and nestin. Mechanistically, RNF138 may interfere with the self-renewal ability of GSCs by regulating the expression of p53. RNF138 downregulation in vivo prolonged survival time and regulated the expression of p53 protein in tumor-bearing mice.

CONCLUSION

RNF138 may regulate the expression of p53 protein through ubiquitination, thereby affecting the self-renewal and tumorigenic ability of GSCs. This study provides a scientific basis for the treatment of glioblastoma by targeting RNF138 to inhibit GSCs.

Exosomal miR-105-5p derived from bladder cancer stem cells targets for GPR12 to promote the malignancy of bladder cancer

Bladder cancer stem cells (BCSCs) are considered as the root cause of BC initiation and recurrence, and exosomes derived from BCSCs (CSCs-exo) are the vital tool for establishing a stable tumor microenvironment. miR-105-5p has been revealed to promote tumor growth in a variety of cancers, but the effects on BC are still not included.Characteristics of CSCs-exo were examined by transmission electron microscope and nanoparticle tracking analysis. PKH67 dye was used to observe the cellular uptake of exosomes. Cell viability, migration and invasion were detected by CCK-8, wound healing and transwell invasion assays, respectively. The interaction between miR-105-5p and GPR12 was verified by luciferase activity assay. Xenografts were induced in the nude mice, and H&E staining method was applied to analyze the histological changes of xenografts. CSCs-exo efficiently promoted BC cell viability, migration and invasion. miR-105-5p was highly expressed in CSCs and CSCs-exo treatment significantly upregulated the expression of miR-105-5p in BC cells.GPR12 was subsequently verified to be the target gene of miR-105-5p, and overexpression of GPR12 abrogated the effects of miR-105-5p on BC cell growth and metastasis. Reversely, the anti-tumor function of miR-105-5p antagomir was observed in the xenograft mice.CSCs aggravated the malignancy of BC partly through transmitting exosomal miR-105-5p to BC cells to inhibit the expression of GPR12, which developed a novel aspect for CSC-targeted therapies.

Cancer Stem Cells and Glioblastoma: Time for Innovative Biomarkers of Radio-Resistance?

Despite countless papers in the field of radioresistance, researchers are still far from clearly understanding the mechanisms triggered in glioblastoma. Cancer stem cells (CSC) are important to the growth and spread of cancer, according to many studies. In addition, more recently, it has been suggested that CSCs have an impact on glioblastoma patients' prognosis, tumor aggressiveness, and treatment outcomes. In reviewing this new area of biology, we will provide a summary of the most recent research on CSCs and their role in the response to radio-chemotherapy in GB. In this review, we will examine the radiosensitivity of stem cells. Moreover, we summarize the current knowledge of the biomarkers of stemness and evaluate their potential function in the study of radiosensitivity.

Clinical Theranostics Trademark of Exosome in Glioblastoma Metastasis

Glioblastoma (GBM) is an aggressive type of cancer that has led to the death of a large population. The traditional approach fails to develop a solution for GBM's suffering life. Extensive research into tumor microenvironments (TME) indicates that TME extracellular vesicles (EVs) play a vital role in cancer development and progression. EVs are classified into microvacuoles, apoptotic bodies, and exosomes. Exosomes are the most highlighted domains in cancer research. GBM cell-derived exosomes participate in multiple cancer progression events such as immune suppression, angiogenesis, premetastatic niche formation (PMN), ECM (extracellular matrix), EMT (epithelial-to-mesenchymal transition), metastasis, cancer stem cell development and therapeutic and drug resistance. GBM exosomes also carry the signature of a glioblastoma-related status. The exosome-based GBM examination is part of the new generation of liquid biopsy. It also solved early diagnostic limitations in GBM. Traditional therapeutic approaches do not cross the blood-brain barrier (BBB). Exosomes are a game changer in GBM treatment and it is emerging as a potential platform for effective, efficient, and specific therapeutic development. In this review, we have explored the exosome-GBM interlink, the clinical impact of exosomes on GBM biomarkers, the therapeutics signature of exosomes in GBM, exosome-based research challenges, and future directions in GBM. Therefore, the GBM-derived exosomes offer unique therapeutic opportunities, which are currently under preclinical and clinical testing.

Two "Edges" in Our Knowledge on the Functions of Ribosomal Proteins: The Revealed Contributions of Their Regions to Translation Mechanisms and the Issues of Their Extracellular Transport by Exosomes

Ribosomal proteins (RPs), the constituents of the ribosome, belong to the most abundant proteins in the cell. A highly coordinated network of interactions implicating RPs and ribosomal RNAs (rRNAs) forms the functionally competent structure of the ribosome, enabling it to perform translation, the synthesis of polypeptide chain on the messenger RNA (mRNA) template. Several RPs contact ribosomal ligands, namely, those with transfer RNAs (tRNAs), mRNA or translation factors in the course of translation, and the contribution of a number of these particular contacts to the translation process has recently been established. Many ribosomal proteins also have various extra-ribosomal functions unrelated to translation. The least-understood and -discussed functions of RPs are those related to their participation in the intercellular communication via extracellular vesicles including exosomes, etc., which often carry RPs as passengers. Recently reported data show that such a kind of communication can reprogram a receptor cell and change its phenotype, which is associated with cancer progression and metastasis. Here, we review the state-of-art ideas on the implications of specific amino acid residues of RPs in the particular stages of the translation process in higher eukaryotes and currently available data on the transport of RPs by extracellular vesicles and its biological effects.

Biogenesis, Composition and Potential Therapeutic Applications of Mesenchymal Stem Cells Derived Exosomes in Various Diseases

Exosomes are nanovesicles with a wide range of chemical compositions used in many different applications. Mesenchymal stem cell-derived exosomes (MSCs-EXOs) are spherical vesicles that have been shown to mediate tissue regeneration in a variety of diseases, including neurological, autoimmune and inflammatory, cancer, ischemic heart disease, lung injury, and liver fibrosis. They can modulate the immune response by interacting with immune effector cells due to the presence of anti-inflammatory compounds and are involved in intercellular communication through various types of cargo. MSCs-EXOs exhibit cytokine storm-mitigating properties in response to COVID-19. This review discussed the potential function of MSCs-EXOs in a variety of diseases including neurological, notably epileptic encephalopathy and Parkinson's disease, cancer, angiogenesis, autoimmune and inflammatory diseases. We provided an overview of exosome biogenesis and factors that regulate exosome biogenesis. Additionally, we highlight the functions and potential use of MSCs-EXOs in the treatment of the inflammatory disease COVID-19. Finally, we covered a strategies and challenges of MSCs-EXOs. Finally, we discuss conclusion and future perspectives of MSCs-EXOs.

Role of cancer stem cell-derived extracellular vesicles in cancer progression and metastasis

Cancer is one of the leading causes of mortality worldwide. Numerous strategies have been developed for cancer treatment. Metastasis, heterogeneity, chemotherapy resistance, recurrence, and evasion of immune surveillance are the primary reasons for the failure of cancer treatment. Cancer stem cells (CSCs) can give rise to tumors via self-renewal and differentiation into various cell types. They show resistance to chemotherapy and radiotherapy and have a strong capability of invasion and metastasis. Extracellular vesicles (EVs) are bilayered vesicles that carry biological molecules and are released under both healthy and unhealthy conditions. It has been shown that one of the leading causes of cancer treatment failure is cancer stem cell-derived EVs (CSC-EVs). CSC-EVs have essential roles in tumor progression, metastasis, tumor angiogenesis, chemoresistance, and immunosuppressants. In the future, controlling EV production in CSCs may be one of the most promising strategies to stop cancer treatment failures.

Digging the intercellular crosstalk via extracellular vesicles: May exosomes be the drug delivery solution for target glioblastoma?

Glioblastoma (GBM) is an adult's most aggressive brain tumor. The advances in molecular pathology and cell signaling pathways have deepened researchers' understanding of intercellular communication mechanisms that can induce tumor progression, namely the release of extracellular vesicles. Exosomes are small extracellular vesicles in various biological fluids released by almost all cells, thus carrying various biomolecules specific to their parental cell. Several pieces of evidence indicate that exosomes mediate intercellular communication in the tumor microenvironment and cross the blood-brain barrier (BBB), valuable tools for diagnostic and therapeutic applications under the scope of brain diseases such as brain tumors. This review aims to resume the several biological characteristics and the interplay between glioblastoma and exosomes, describing highlight studies that demonstrate the role of exosomes in the tumor microenvironment of GBM and their potential for non-invasive diagnoses and therapeutic approaches, namely, as nanocarriers for drug or gene delivery and cancer vaccines.

Extracellular vesicles throughout development: A potential roadmap for emerging glioblastoma therapies

Extracellular vesicles (EVs) are membrane-delimited vesicular bodies carrying different molecules, classified according to their size, density, cargo, and origin. Research on this topic has been actively growing through the years, as EVs are associated with critical pathological processes such as neurodegenerative diseases and cancer. Despite that, studies exploring the physiological functions of EVs are sparse, with particular emphasis on their role in organismal development, initial cell differentiation, and morphogenesis. In this review, we explore the topic of EVs from a developmental perspective, discussing their role in the earliest cell-fate decisions and neural tissue morphogenesis. We focus on the function of EVs through development to highlight possible conserved or novel processes that can impact disease progression. Specifically, we take advantage of what was learned about their role in development so far to discuss EVs impact on glioblastoma, a particular brain tumor of stem-cell origin and poor prognosis, and how their function can be hijacked to improve current therapies.

Exosomal microRNA-4535 of Melanoma Stem Cells Promotes Metastasis by Inhibiting Autophagy Pathway

High mortality rate and poor survival in melanoma are associated with efficient metastatic colonization. The underlying mechanisms remain elusive. Elucidating the role of exosomes in mediating the interactions between cancer cells and the metastatic microenvironment has been focused on cancer cell derived exosomes in modulating the functions of stromal cells. Whether cancer stem cells (CSCs) can modify the metastatic properties of non-CSC cells, and whether exosomal crosstalk plays a role have not been demonstrated prior to this report. In this study, a paired M14 melanoma derivative cell line, i.e., melanoma parental cell (MPC) and its CSC derivative cell line melanoma stem cell (MSC) were employed. We demonstrated that exosomal crosstalk betwen MSCs and non-CSC MPCs is a new mechanism that underlies melanoma metastasis. Low metastatic melanoma cells (MPCs) can acquire the "metastatic power" from highly metastatic melanoma CSCs (MSCs). We illustrated an uncharacterized microRNA, miR-4535 in mediating such exosomal crosstalk. MSCs deliver its exosomal miR-4535 to the targeted MPCs. Upon entering MPCs, miR-4535 augments metastatic colonization of MPCs by inactivating the autophagy pathway.

ADAMTS1 as potential prognostic biomarker promotes malignant invasion of glioma

BACKGROUND

Glioma is the most common intracranial malignancy in adults with a high degree of malignancy and poor prognosis, which is largely attributed to the existence of glioma stem cells (GSCs). Previous evidence indicated that the matrix metalloproteinase ADAMTS1 was implicated in the process of tumor invasion, but the involvement of ADAMTS1 in glioma malignant invasion remains poorly understood.

METHODS

The expression and prognosis values of ADAMTS1 were investigated in patients with glioma based on ONCOMINE and GEPIA databases. ADAMTS1 expression of different malignancy grade tissues was determined by immunohistochemistry. The effects of ADAMTS1 on cell proliferation and invasion were determined by clone formation assay and Transwell migration assay. The animal experiment was performed in an intracranial orthotopic xenograft model by knockout of ADAMTS1. Stemness properties and Notch1-SOX2 pathway were examined in stable ADAMTS1 knockdown GSCs.

RESULTS

The expression levels of ADAMTS1 were significantly higher in glioma tissues and significantly correlated with the grade of malignancy and prognosis of glioma. Elevated ADAMTS1 expression was associated with SOX2, N-cadherin and the resistance of chemoradiotherapy of glioma patients. ADAMTS1 knockout suppressed the intracranial orthotopic xenograft growth and prolonged the survival of xenograft mice in vivo. Mechanistically, we found a blockade of the migration and invasiveness of GSCs and the expression levels of Notch1 and SOX2 in absence of ADAMTS1.

CONCLUSION

As a biomarker for prediction of prognosis, ADAMTS1 may affect the invasive phenotype of GSCs by regulating Notch1-SOX2 signaling pathway, thereby promoting the invasive growth of glioma.

The metastatic niche formation: focus on extracellular vesicle-mediated dialogue between lung cancer cells and the microenvironment

Lung cancer is the deadliest cancer in the world, with the majority of patients presenting with advanced or metastatic disease at first diagnosis. The lungs are also one of the most common sites of metastasis from lung cancer and other tumors. Understanding the mechanisms that regulate metastasis formation from primary lung cancer and in the lungs is therefore fundamental unmet clinical need. One of the first steps during the establishment of lung cancer metastases includes the formation of the pre-metastatic niche (PMN) at distant organs, which may occur even during the early phases of cancer development. The PMN is established through intricate cross-talk between primary tumor-secreted factors and stromal components at distant sites. Mechanisms controlling primary tumor escape and seeding of distant organs rely on specific properties of tumor cells but are also tightly regulated by interactions with stromal cells at the metastatic niche that finally dictate the success of metastasis establishment. Here, we summarize the mechanisms underlying pre-metastatic niche formation starting from how lung primary tumor cells modulate distant sites through the release of several factors, focusing on Extracellular Vesicles (EVs). In this context, we highlight the role of lung cancer-derived EVs in the modulation of tumor immune escape. Then, we illustrate the complexity of Circulating Tumor Cells (CTCs) that represent the seeds of metastasis and how interactions with stromal and immune cells can help their metastatic dissemination. Finally, we evaluate the contribution of EVs in dictating metastasis development at the PMN through stimulation of proliferation and control of disseminated tumor cell dormancy. Overall, we present an overview of different steps in the lung cancer metastatic cascade, focusing on the EV-mediated interactions between tumor cells and stromal/immune cells.

The Role of Cancer Stem Cells and Their Extracellular Vesicles in the Modulation of the Antitumor Immunity

Cancer stem cells (CSCs) are a population of tumor cells that share similar properties to normal stem cells. CSCs are able to promote tumor progression and recurrence due to their resistance to chemotherapy and ability to stimulate angiogenesis and differentiate into non-CSCs. Cancer stem cells can also create a significant immunosuppressive environment around themselves by suppressing the activity of effector immune cells and recruiting cells that support tumor escape from immune response. The immunosuppressive effect of CSCs can be mediated by receptors located on their surface, as well as by secreted molecules, which transfer immunosuppressive signals to the cells of tumor microenvironment. In this article, the ability of CSCs to regulate the antitumor immune response and a contribution of CSC-derived EVs into the avoidance of the immune response are discussed.

The Role of Tumor Microenvironment in Regulating the Plasticity of Osteosarcoma Cells

Osteosarcoma (OS) is a malignancy that is becoming increasingly common in adolescents. OS stem cells (OSCs) form a dynamic subset of OS cells that are responsible for malignant progression and chemoradiotherapy resistance. The unique properties of OSCs, including self-renewal, multilineage differentiation and metastatic potential, 149 depend closely on their tumor microenvironment. In recent years, the likelihood of its dynamic plasticity has been extensively studied. Importantly, the tumor microenvironment appears to act as the main regulatory component of OS cell plasticity. For these reasons aforementioned, novel strategies for OS treatment focusing on modulating OS cell plasticity and the possibility of modulating the composition of the tumor microenvironment are currently being explored. In this paper, we review recent studies describing the phenomenon of OSCs and factors known to influence phenotypic plasticity. The microenvironment, which can regulate OSC plasticity, has great potential for clinical exploitation and provides different perspectives for drug and treatment design for OS.

Extracellular vesicles as source for the identification of minimally invasive molecular signatures in glioblastoma

The analysis of extracellular vesicles (EVs) as a source of cancer biomarkers is an emerging field since low-invasive biomarkers are highly demanded. EVs constitute a heterogeneous population of small membrane-contained vesicles that are present in most of body fluids. They are released by all cell types, including cancer cells and their cargo consists of nucleic acids, proteins and metabolites and varies depending on the biological-pathological state of the secretory cell. Therefore, EVs are considered as a potential source of reliable biomarkers for cancer. EV biomarkers in liquid biopsy can be a valuable tool to complement current medical technologies for cancer diagnosis, as their sampling is minimally invasive and can be repeated over time to monitor disease progression. In this review, we highlight the advances in EV biomarker research for cancer diagnosis, prognosis, and therapy monitoring. We especially focus on EV derived biomarkers for glioblastoma. The diagnosis and monitoring of glioblastoma still relies on imaging techniques, which are not sufficient to reflect the highly heterogenous and invasive nature of glioblastoma. Therefore, we discuss how the use of EV biomarkers could overcome the challenges faced in diagnosis and monitoring of glioblastoma.

miR-30c plays diagnostic and prognostic roles and mediates epithelial-mesenchymal transition (EMT) and proliferation of gliomas by affecting Notch1

miR-30c functions as a tumor suppressor gene in the majority of tumors, including gliomas. In our study, we discovered that the expression levels of miR-30c in glioma tissues and plasma prior to surgery were lower than those in normal brain tissue following brain injury decompression and in plasma in healthy volunteers. The low expression of miR-30c was closely aligned with the WHO grade, tumor size, PFS, and OS. Additionally, the miR-30c expression level in tumor tissue was positively correlated with the levels in preoperative plasma. In cell biology experiments, miR-30c inhibited EMT and proliferation, migration, and invasion of glioma cells. Analysis of databases of miRNA target genes, real-time quantitative PCR, western blotting, and dual luciferase reporter assays demonstrated that Notch1 is the direct target gene of miR-30c. An inhibitor and shRNA-Notch1 were cotransfected into glioma cells, and it was found that shRNA-Notch1 reduced the enhancement of inhibitors of EMT and proliferation, migration, and invasion of glioma cells. Therefore, we believe that when utilized as a tumor suppressor gene, miR-30c can inhibit EMT and the proliferation, migration, and invasion of glioma cells by directly acting on Notch1 at the posttranscriptional level and that it is a potential diagnostic and prognostic marker.

Tumor-derived small extracellular vesicles: potential roles and mechanism in glioma

Small extracellular vesicles (SEVs) are extracellular vesicles containing DNA, RNA, and proteins and are involved in intercellular communication and function, playing an essential role in the growth and metastasis of tumors. SEVs are present in various body fluids and can be isolated and extracted from blood, urine, and cerebrospinal fluid. Under both physiological and pathological conditions, SEVs can be released by some cells, such as immune, stem, and tumor cells, in a cytosolic manner. SEVs secreted by tumor cells are called tumor-derived exosomes (TEXs) because of their origin in the corresponding parent cells. Glioma is the most common intracranial tumor, accounting for approximately half of the primary intracranial tumors, and is characterized by insidious onset, high morbidity, and high mortality rate. Complete removal of tumor tissues by surgery is difficult. Chemotherapy can improve the survival quality of patients to a certain extent; however, gliomas are prone to chemoresistance, which seriously affects the prognosis of patients. In recent years, TEXs have played a vital role in the occurrence, development, associated immune response, chemotherapy resistance, radiation therapy resistance, and metastasis of glioma. This article reviews the role of TEXs in glioma progression, drug resistance, and clinical diagnosis.

Exosome-based strategies for diagnosis and therapy of glioma cancer

Glioblastoma belongs to the most aggressive type of cancer with a low survival rate that is characterized by the ability in forming a highly immunosuppressive tumor microenvironment. Intercellular communication are created via exosomes in the tumor microenvironment through the transport of various biomolecules. They are primarily involved in tumor growth, differentiation, metastasis, and chemotherapy or radiation resistance. Recently several studies have highlighted the critical role of tumor-derived exosomes against immune cells. According to the structural and functional properties, exosomes could be essential instruments to gain a better molecular mechanism for tumor understanding. Additionally, they are qualified as diagnostic/prognostic markers and therapeutic tools for specific targeting of invasive tumor cells such as glioblastomas. Due to the strong dependency of exosome features on the original cells and their developmental status, it is essential to review their critical modulating molecules, clinical relevance to glioma, and associated signaling pathways. This review is a non-clinical study, as the possible role of exosomes and exosomal microRNAs in glioma cancer are reported. In addition, their content to overcome cancer resistance and their potential as diagnostic biomarkers are analyzed.

Ribosomes and Ribosomal Proteins Promote Plasticity and Stemness Induction in Glioma Cells via Reprogramming

Glioblastoma multiforme (GBM) is a lethal tumor that develops in the adult brain. Despite advances in therapeutic strategies related to surgical resection and chemo-radiotherapy, the overall survival of patients with GBM remains unsatisfactory. Genetic research on mutation, amplification, and deletion in GBM cells is important for understanding the biological aggressiveness, diagnosis, and prognosis of GBM. However, the efficacy of drugs targeting the genetic abnormalities in GBM cells is limited. Investigating special microenvironments that induce chemo-radioresistance in GBM cells is critical to improving the survival and quality of life of patients with GBM. GBM cells acquire and maintain stem-cell-like characteristics via their intrinsic potential and extrinsic factors from their special microenvironments. The acquisition of stem-cell-like phenotypes and aggressiveness may be referred to as a reprogramming of GBM cells. In addition to protein synthesis, deregulation of ribosome biogenesis is linked to several diseases including cancer. Ribosomal proteins possess both tumor-promotive and -suppressive functions as extra-ribosomal functions. Incorporation of ribosomes and overexpression of ribosomal protein S6 reprogram and induce stem-cell-like phenotypes in GBM cells. Herein, we review recent literature and our published data on the acquisition of aggressiveness by GBM and discuss therapeutic options through reprogramming.

Analysis of Exosomal Cargo Provides Accurate Clinical, Histologic and Mutational Information in Non-Small Cell Lung Cancer

Simple Summary

Non-small cell lung cancer (NSCLC) is the second most commonly diagnosed cancer and the leading cause of cancer-related death worldwide. Clinical decision-making depends on the histological classification; however, tissue biopsy is frequently not technically feasible due to tumor location or limited tissue samples. Therefore, we propose to find clinical, molecular and histological biomarkers using a minimally invasive approach based on the analysis of the cargo of the blood extracellular vesicles. Exosomes are membranous vesicles present in several biological fluids, which carry biological information to distant tissues, regulating several tumor processes. This study aims to analyze NSCLC exosome cargo for search biomarkers that could improve clinical management. This report demonstrates the possibility of implementing exosomes to detect molecular alterations and as a source of biomarkers to differentiate NSCLC histology, allowing for a new approach in precision oncology.

Abstract

Lung cancer is a malignant disease with high mortality and poor prognosis, frequently diagnosed at advanced stages. Nowadays, immense progress in treatment has been achieved. However, the present scenario continues to be critical, and a full comprehension of tumor progression mechanisms is required, with exosomes being potentially relevant players. Exosomes are membranous vesicles that contain biological information, which can be transported cell-to-cell and modulate relevant processes in the hallmarks of cancer. The present research aims to characterize the exosomes’ cargo and study their role in NSCLC to identify biomarkers. We analyzed exosomes secreted by primary cultures and cell lines, grown in monolayer and tumorsphere formations. Exosomal DNA content showed molecular alterations, whereas RNA high-throughput analysis resulted in a pattern of differentially expressed genes depending on histology. The most significant differences were found in XAGE1B, CABYR, NKX2-1, SEPP1, CAPRIN1, and RIOK3 genes when samples from two independent cohorts of resected NSCLC patients were analyzed. We identified and validated biomarkers for adenocarcinoma and squamous cell carcinoma. Our results could represent a relevant contribution concerning exosomes in clinical practice, allowing for the identification of biomarkers that provide information regarding tumor features, prognosis and clinical behavior of the disease.

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.

EV-Mediated Chemoresistance in the Tumor Microenvironment: Is NF-κB a Player?

Drug resistance is a major impediment to patient survival and remains the primary cause of unsuccessful cancer therapy. Drug resistance occurs in many tumors and is frequently induced by chemotherapy which triggers a defensive response both in cancerous and cancer-associated cells that constitute the tumor microenvironment (TME). Cell to cell communication within the TME is often mediated by extracellular vesicles (EVs) which carry specific tumor-promoting factors able to activate survival pathways and immune escape mechanisms, thus sustaining tumor progression and therapy resistance. NF-κB has been recognized as a crucial player in this context. NF-κB activation is involved in EVs release and EVs, in turn, can trigger NF-κB pathway activation in specific contexts, based on secreting cytotype and their specific delivered cargo. In this review, we discuss the role of NF-κB/EVs interplay that sustain chemoresistance in the TME by focusing on the molecular mechanisms that underlie inflammation, EVs release, and acquired drug resistance.

Angioregulatory role of miRNAs and exosomal miRNAs in glioblastoma pathogenesis

Glioblastoma (GB) is a highly aggressive cancer of the central nervous system, occurring in the brain or spinal cord. Many factors such as angiogenesis are associated with GB development. Angiogenesis is a procedure by which the pre-existing blood vessels create new vessels that play an essential role in health and disease, including tumors. Also, angiogenesis is one of the significant factors thought to be responsible for treatment resistance in many tumors, including GB. Hence, an improved understanding of the molecular processes underlying GB angiogenesis will pave the way for developing potential new treatments. Recently, it has been found that microRNAs (miRNAs) and exosomal miRNAs have a crucial role in inducing or inhibiting the angiogenesis process in GB development. A better knowledge of the miRNA's regulation pathway in the angiogenesis process in cancer offers unique mechanistic insight into the mechanism of tumor-associated neovascularization. Because of advancements in miRNA characterization and delivery methods, miRNAs can also be employed in clinical settings as potential biomarkers for anti-angiogenic treatment response as well as therapies targeting tumor angiogenesis. The recent finding and insights about miRNAs' angioregulatory role and exosomal miRNAs in GB are provided throughout the review. Also, we discuss the new concept of miRNAs-based therapies for GB in the future.

The Clinical Significance of Transfer RNAs Present in Extracellular Vesicles

Extracellular vesicles (EVs) are important for intercellular signalling in multi-cellular organisms. However, the role of mature transfer RNAs (tRNAs) and tRNA fragments in EVs has yet to be characterised. This systematic review aimed to identify up-to-date literature on tRNAs present within human EVs and explores their potential clinical significance in health and disease. A comprehensive and systematic literature search was performed, and the study was conducted in accordance with PRISMA guidelines. Electronic databases MEDLINE and EMBASE were searched up until 1 January 2022. From 685 papers, 60 studies were identified for analysis. The majority of papers reviewed focussed on the role of EV tRNAs in cancers (31.7%), with numerous other conditions represented. Blood and cell lines were the most common EV sources, representing 85.9% of protocols used. EV isolation methods included most known methods, precipitation being the most common (49.3%). The proportion of EV tRNAs was highly variable, ranging between 0.04% to >95% depending on tissue source. EV tRNAs are present in a multitude of sources and show promise as disease markers in breast cancer, gastrointestinal cancers, and other diseases. EV tRNA research is an emerging field, with increasing numbers of papers highlighting novel methodologies for tRNA and tRNA fragment discovery.

Effects of exosomes on adult hippocampal neurogenesis and neuropsychiatric disorders

Exosomes are extracellular vesicles originating from the endosomal system, which are involved in intercellular substance transfer and cell waste elimination. Recent studies implicate the roles of exosomes in adult hippocampal neurogenesis, a process through which new granule cells are generated in the dentate gyrus, and which is closely related to mood and cognition, as well as psychiatric disorders. As such, exosomes are recognized as potential biomarkers of neurologic and psychiatric disorders. This review briefly introduces the synthesis and secretion mechanism of exosomes, and discuss the relationship between exosomes and hippocampal neurogenesis, and their roles in regulating depression, epilepsy and schizophrenia. Finally, we discuss the prospects of their application in diagnosing disorders of the central nervous system (CNS).

NOX4 regulates TGFβ-induced proliferation and self-renewal in glioblastoma stem cells

Glioblastoma (GBM) is the most aggressive and common glioma subtype, with a median survival of 15 months after diagnosis. Current treatments have limited therapeutic efficacy; thus, more effective approaches are needed. The glioblastoma tumoural mass is characterised by a small cellular subpopulation – glioblastoma stem cells (GSCs) – that has been held responsible for glioblastoma initiation, cell invasion, proliferation, relapse and resistance to chemo‐ and radiotherapy. Targeted therapies against GSCs are crucial, as is understanding the molecular mechanisms that govern the GSCs. Transforming growth factor β (TGFβ) signalling and reactive oxygen species (ROS) production are known to govern and regulate cancer stem cell biology. Among the differentially expressed genes regulated by TGFβ in a transcriptomic analysis of two different patient‐derived GSCs, we found NADPH oxidase 4 (NOX4) as one of the top upregulated genes. Interestingly, when patient tissues were analysed, NOX4 expression was found to be higher in GSCs versus differentiated cells. A functional analysis of the role of NOX4 downstream of TGFβ in several patient‐derived GSCs showed that TGFβ does indeed induce NOX4 expression and increases ROS production in a NOX4‐dependent manner. NOX4 downstream of TGFβ regulates GSC proliferation, and NOX4 expression is necessary for TGFβ‐induced expression of stem cell markers and of the transcription factor nuclear factor erythroid 2‐related factor 2 (NRF2), which in turn controls the cell’s antioxidant and metabolic responses. Interestingly, overexpression of NOX4 recapitulates the effects induced by TGFβ in GSCs: enhanced proliferation, stemness and NRF2 expression. In conclusion, this work functionally establishes NOX4 as a key mediator of GSC biology.

Exosomes as Drug Carriers in Anti-Cancer Therapy

Over the years, there has been a high demand for developing new safe and effective drug carriers for cancer therapy. Emerging studies have indicated that exosomes can serve as potent therapeutic carriers since they offer low immunogenicity, high stability, innate and acquired targetability, and the stimulation of anti-cancer immune responses. Yet, the development of exosome-based drug delivery systems remains challenging due to their heterogeneity, low yield, and limited drug loading efficiency. Herein, we summarized the current application of exosomes derived from different cells as drug carriers in anti-cancer therapy in vitro and in vivo. We also discussed the challenges and prospects of exosome-based drug delivery systems in cancer therapy.

Human umbilical vein endothelial cells derived-exosomes promote osteosarcoma cell stemness by activating Notch signaling pathway

Osteosarcoma is one of the most common primary malignant tumors of bone in adolescents. Human umbilical vein endothelial cells (HUVECs) derived exosomes are associated with osteosarcoma cell stemness. Little is known about the function of HUVECs-exosomes in osteosarcoma cell stemness. This work aimed to investigate the mechanism of action of HUVECs-exosomes in regulating stem cell-like phenotypes of osteosarcoma cells. HUVECs were treated with GW4869 (exosome inhibitor). Human osteosarcoma cells (U2OS and 143B) were treated with HUVECs supernatant, HUVECs-exosomes with or without RO4929097 (γ secretase inhibitor, used to block Notch signaling pathway). We found that HUVECs supernatant and HUVECs-exosomes enhanced the proportions of STRO-1⁺CD117⁺ cells and the expression of stem cell-related proteins Oct4 and Sox2. Both HUVECs supernatant and HUVECs-exosomes promoted the sarcosphere formation efficiency of U2OS and 143B cells. These stem-like phenotypes of U2OS and 143B cells conferred by HUVECs-exosomes were repressed by GW4869. Moreover, HUVECs-exosomes promoted the expression of Notch1, Hes1 and Hey1 in the U2OS and 143B cells. RO4929097 treatment reversed the impact of HUVECs-exosomes on Notch1, Hes1, and Hey1 expression by inhibiting Notch1 signaling pathway. In conclusion, this work demonstrated that HUVECs-exosomes promoted cell stemness in osteosarcoma through activating Notch signaling pathway. Thus, our data reveal the mechanism of HUVECs-exosomes in regulating cell stemness of osteosarcoma, and provide a theoretical basis for osteosarcoma treatment by exosomes.

The Roles of Exosomes as Future Therapeutic Agents and Diagnostic Tools for Glioma

Glioma is a common type of tumor originating in the brain. Glioma develops in the gluey supporting cells (glial cells) that surround and support nerve cells. Exosomes are extracellular vesicles that contain microRNAs, messenger RNA, and proteins. Exosomes are the most prominent mediators of intercellular communication, regulating, instructing, and re-educating their surrounding milieu targeting different organs. As exosomes' diameter is in the nano range, the ability to cross the blood-brain barrier, a crucial obstacle in developing therapeutics against brain diseases, including glioma, makes the exosomes a potential candidate for delivering therapeutic agents for targeting malignant glioma. This review communicates the current knowledge of exosomes' significant roles that make them crucial future therapeutic agents and diagnostic tools for glioma.

Extracellular Vesicles and Cancer Stem Cells in Tumor Progression: New Therapeutic Perspectives

Tumor burden is a complex microenvironment where different cell populations coexist and have intense cross-talk. Among them, a heterogeneous population of tumor cells with staminal features are grouped under the definition of cancer stem cells (CSCs). CSCs are also considered responsible for tumor progression, drug resistance, and disease relapse. Furthermore, CSCs secrete a wide variety of extracellular vesicles (EVs) with different cargos, including proteins, lipids, ssDNA, dsDNA, mRNA, siRNA, or miRNA. EVs are internalized by other cells, orienting the microenvironment toward a protumorigenic and prometastatic one. Given their importance in tumor growth and metastasis, EVs could be exploited as a new therapeutic target. The inhibition of biogenesis, release, or uptake of EVs could represent an efficacious strategy to impair the cross-talk between CSCs and other cells present in the tumor microenvironment. Moreover, natural or synthetic EVs could represent suitable carriers for drugs or bioactive molecules to target specific cell populations, including CSCs. This review will discuss the role of CSCs and EVs in tumor growth, progression, and metastasis and how they affect drug resistance and disease relapse. Furthermore, we will analyze the potential role of EVs as a target or vehicle of new therapies.

Brain endothelial cells-derived extracellular vesicles overexpressing ECRG4 inhibit glioma proliferation through suppressing inflammation and angiogenesis

Esophageal cancer related gene-4 (ECRG4) has been shown to be a candidate tumor suppressor in many tumors, but its role in glioma remains poorly understood. This study aimed to explore whether extracellular vesicles (EVs) derived from brain endothelial cells which overexpressed ECRG4 have anti-tumor effect on gliomas in vivo and in vitro, as well as the possible mechanism. A constructed lentivirus expressing the ECRG4 gene was transfected into the hCMEC/D3 cell line. The EVs were isolated from the cells and characterized by Western blot with exosome markers of CD9, CD63, CD81, Alix. RT-PCR and Western blot were performed to verify ECRG4 expression. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and clone formation assays were applied to detect the proliferation of glioma cells incubated with EVs expressing the ECRG4 (ECRG4-exo). The level of inflammatory cytokines and angiogenesis related factors, including nuclear factor kappa-B (NF-κB), interleukin (IL)-1β, IL-6, IL-8, monocyte chemoattractant protein-1 (MCP-1), hypoxia-inducible factor 1-alpha (HIF-1α), vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor 2 (VEGFR2) levels were detected by ELISA. The T98G cell xenograft mouse model was established and treated with ECRG4-EV. The tumor volume and weight were recorded. p38-MAPK, p-p38-MAPK proteins were determined by Western blot in tumor tissues. As a result, EVs can be internalized into U87MG and T98G cells. ECRG4-EV inhibited U87MG and T98G cell proliferation. ECRG4-EV also inhibited the expression of factors involved in inflammation and angiogenesis. In addition, ECRG4-EVs suppressed tumor growth and decreased the production of inflammatory cytokines through inactivation of p38-MAPK signal pathway. In conclusion, ECRG4-EVsuppresses glioma proliferation through modulating the inflammation and angiogenesis.

Netrin-1 in Glioblastoma Neovascularization: The New Partner in Crime?

Glioblastoma (GBM) is the most aggressive and common primary tumor of the central nervous system. It is characterized by having an infiltrating growth and by the presence of an excessive and aberrant vasculature. Some of the mechanisms that promote this neovascularization are angiogenesis and the transdifferentiation of tumor cells into endothelial cells or pericytes. In all these processes, the release of extracellular microvesicles by tumor cells plays an important role. Tumor cell-derived extracellular microvesicles contain pro-angiogenic molecules such as VEGF, which promote the formation of blood vessels and the recruitment of pericytes that reinforce these structures. The present study summarizes and discusses recent data from different investigations suggesting that Netrin-1, a highly versatile protein recently postulated as a non-canonical angiogenic ligand, could participate in the promotion of neovascularization processes in GBM. The relevance of determining the angiogenic signaling pathways associated with the interaction of Netrin-1 with its receptors is posed. Furthermore, we speculate that this molecule could form part of the microvesicles that favor abnormal tumor vasculature. Based on the studies presented, this review proposes Netrin-1 as a novel biomarker for GBM progression and vascularization.

JARID2 promotes stemness and cisplatin resistance in non-small cell lung cancer via upregulation of Notch1

Increased stemness is causally linked to development of drug resistance in cancers. JARID2 is a member of the Jumonji family of proteins and regulates differentiation of embryonic stem cells. However, the role of JARID2 in lung cancer stemness and drug resistance is still unclear. In this study, we investigated the expression of JARID2 in parental and cisplatin (CDDP) resistant non-small cell lung cancer (NSCLC) cells. The function of JARID2 in modulating CDDP sensitivity of NSCLC cells was determined. It was found that JARID2 is upregulated in CDDP resistant NSCLC cells, which depends on SOX2 expression. JARID2 overexpression promotes CDDP resistance in NSCLC cells, whereas JARID2 depletion restores CDDP sensitivity in CDDP resistant NSCLC cells. Moreover, JARID2 overexpression enhances cancer stem cell-like properties in NSCLC cells, which is coupled with increased expression of cancer stem cell markers. Mechanistically, JARID2-induced stemness and CDDP resistance is mediated by upregulation of Notch1. In clinical settings, high expression of JARID2 is significantly associated with advanced TNM stage, shorter overall survival, and poor chemotherapeutic response. These findings point toward an important role of JARID2 in CDDP resistance and stemness of NSCLC and provide a promising target for overcoming CDDP resistance.

Exosomes from cervical cancer cells facilitate pro-angiogenic endothelial reconditioning through transfer of Hedgehog-GLI signaling components

BACKGROUND

Angiogenic switch is a hallmark feature of transition from low-grade to high-grade cervical intraepithelial neoplasia (CIN) in cervical cancer progression. Therefore, early events leading to locally-advanced cervical metastatic lesions demand a greater understanding of the underlying mechanisms. Recent leads indicate the role of tumor-derived exosomes in altering the functions of endothelial cells in cervical cancer, which needs further investigation.

METHODS

Exosomes isolated from cervical cancer cell lines were assessed for their angiogenic effect on the human umbilical vein endothelial cells (HUVEC) using tube formation and wound healing assay. The exosomal uptake by HUVEC cells was monitored using PKH-67 labelling followed by fluorescence microscopy. Alterations in Hh-GLI signaling components, PTCH1 and GLI1, in HUVEC were measured by immunoblotting. Changes in angiogenesis-related transcripts of vascular endothelial growth factor VEGF-A, VEGF-B, VEGFR2 and angiopoietin-1, angiopoietin-2, osteopontin were measured in exosome-treated HUVEC and in the exosomal RNA by RT-PCR.

RESULTS

Enhanced tube formation, with an increased number of nodes and branching was observed in HUVEC's treated with exosomes derived from different cervical cancer cell lines. HPV-positive (SiHa and HeLa) cells' exosomes were more angiogenic. Exosome-treated HUVEC showed increased migration rate. PKH-67 labelled exosomes were found internalized in HUVEC. A high level of PTCH1 protein was detected in the exosome-treated endothelial cells. Subsequent RT-PCR analysis showed increased transcripts of Hh-GLI downstream target genes VEGF-A, VEGFR2, angiopoietin-2, and decreased expression of VEGF-B, and angiopoietin-1, suggestive of active Hh-GLI signaling. These effects were more pronounced in HUVEC's treated with exosomes of HPV-positive cells. However, these effects were independent of tumor-derived VEGF-A as exosomal cargo lacked VEGF-A transcripts or proteins.

CONCLUSION

Overall, the data showed cervical cancer exosomes promote pro-angiogenic response in endothelial cells via upregulation of Hh-GLI signaling and modulate downstream angiogenesis-related target genes. The study provides a novel exosome-mediated mechanism potentially favoring cervical angiogenesis and thus identifies the exosomes as potential pharmacological targets against locally-advanced metastatic cervical lesions.

Glioma-Derived Extracellular Vesicles - Far More Than Local Mediators

Extracellular vesicle (EV) secretion is a ubiquitous cellular process with both physiologic and pathologic consequences. EVs are small lipid bilayer vesicles that encompass both microvesicles and exosomes and which are secreted by virtually all cells including cancer cells. In this review, we will focus on the roles of EVs in mediating the crosstalk between glioblastoma (GBM) cells and innate and adaptive immune cells and the potential impact on glioma progression. Glioma-derived EVs contain many bioactive cargoes that can broaden and amplify glioma cell mediated immunosuppressive functions and thereby contribute to shaping the tumor microenvironment. We will discuss evidence demonstrating that the low oxygen (hypoxia) in the GBM microenvironment, in addition to cell-intrinsic effects, can affect intercellular communication through EV release, raising the possibility that properties of the tumor core can more widely impact the tumor microenvironment. Recent advances in glioma-derived EV research have shown their importance not only as message carriers, but also as mediators of immune escape, with the capacity to reprogram tumor infiltrating immune cells. Exploring EV function in cancer-immune crosstalk is therefore becoming an important research area, opening up opportunities to develop EV monitoring for mechanistic studies as well as novel diagnostic glioma biomarker applications. However, robust and reproducible EV analysis is not always routinely established, whether in research or in clinical settings. Taking into account the current state of the art in EV studies, we will discuss the challenges and opportunities for extending the many exciting findings in basic research to a better interpretation of glioma and its response to current and future immunotherapies.

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

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

The Role of Extracellular Vesicles in the Development of a Cancer Stem Cell Microenvironment Niche and Potential Therapeutic Targets: A Systematic Review

Simple Summary

Cancer stem cells (CSCs) are cancer cells that possess traits usually attributed to stem cells. An increase in CSCs can lead to more rapid cancer progression, treatment resistance and the increased likelihood of recurrence. To promote CSC survival and associated cancer progression, cancer cells enter into reciprocal crosstalk with the surrounding tissue environment, as well as with distant metastatic sites. This mechanism of communication relies, in part, on secreted factors, of which extracellular vesicles (EVs) are thought to have a critical role. This systematic review evaluates the current knowledge of cancer communication via EVs to alter the microenvironment to increase the survival and maintenance of CSCs. A total of 16 studies spanning the EV content, pathway alterations and CSC-targeting treatments provide new insights into how EVs mediate CSC traits and identify the gaps in our understanding of how modulation of the microenvironment plays a key role.

Abstract

Cancer stem cells (CSCs) have increasingly been shown to be a crucial element of heterogenous tumors. Although a relatively small component of the population, they increase the resistance to treatment and the likelihood of recurrence. In recent years, it has been shown, across multiple cancer types (e.g., colorectal, breast and prostate), that reciprocal communication between cancer and the microenvironment exists, which is, in part, facilitated by extracellular vesicles (EVs). However, the mechanisms of this method of communication and its influence on CSC populations is less well-understood. Therefore, the aim of this systematic review is to determine the evidence that supports the role of EVs in the manipulation of the tumor microenvironment to promote the survival of CSCs. Embase and PubMed were used to identify all studies on the topic, which were screened using PRISMA guidelines, resulting in the inclusion of 16 studies. These 16 studies reported on the EV content, pathways altered by EVs and therapeutic targeting of CSC through EV-mediated changes to the microenvironment. In conclusion, these studies demonstrated the role of EV-facilitated communication in maintaining CSCs via manipulation of the tumor microenvironment, demonstrating the potential of creating therapeutics to target CSCs. However, further works are needed to fully understand the targetable mechanisms upon which future therapeutics can be based.

Notch-ing up knowledge on molecular mechanisms of skin fibrosis: focus on the multifaceted Notch signalling pathway

Fibrosis can be defined as an excessive and deregulated deposition of extracellular matrix proteins, causing loss of physiological architecture and dysfunction of different tissues and organs. In the skin, fibrosis represents the hallmark of several acquired (e.g. systemic sclerosis and hypertrophic scars) and inherited (i.e. dystrophic epidermolysis bullosa) diseases. A complex series of interactions among a variety of cellular types and a wide range of molecular players drive the fibrogenic process, often in a context-dependent manner. However, the pathogenetic mechanisms leading to skin fibrosis are not completely elucidated. In this scenario, an increasing body of evidence has recently disclosed the involvement of Notch signalling cascade in fibrosis of the skin and other organs. Despite its apparent simplicity, Notch represents one of the most multifaceted, strictly regulated and intricate pathways with still unknown features both in health and disease conditions. Starting from the most recent advances in Notch activation and regulation, this review focuses on the pro-fibrotic function of Notch pathway in fibroproliferative skin disorders describing molecular networks, interplay with other pro-fibrotic molecules and pathways, including the transforming growth factor-β1, and therapeutic strategies under development.