Radiated glioblastoma cell-derived exosomal circ_0012381 induce M2 polarization of microglia to promote the growth of glioblastoma by CCL2/CCR2 axis

The role and application of small extracellular vesicles in glioma

Small extracellular vesicles (sEVs) are cell-derived, nanometer-sized particles enclosed by a lipid bilayer. All kinds of biological molecules, including proteins, DNA fragments, RNA, lipids, and metabolites, can be selectively loaded into sEVs and transmitted to recipient cells that are near and distant. Growing shreds of evidence show the significant biological function and the clinical significance of sEVs in cancers. Numerous recent studies have validated that sEVs play an important role in tumor progression and can be utilized to diagnose, stage, grading, and monitor early tumors. In addition, sEVs have also served as drug delivery nanocarriers and cancer vaccines. Although it is still infancy, the field of basic and translational research based on sEVs has grown rapidly. In this review, we summarize the latest research on sEVs in gliomas, including their role in the malignant biological function of gliomas, and the potential of sEVs in non-invasive diagnostic and therapeutic approaches, i.e., as nanocarriers for drug or gene delivery and cancer vaccines.

Speeding up Glioblastoma Cancer Research: Highlighting the Zebrafish Xenograft Model

Glioblastoma multiforme (GBM) is a very aggressive and lethal primary brain cancer in adults. The multifaceted nature of GBM pathogenesis, rising from complex interactions between cells and the tumor microenvironment (TME), has posed great treatment challenges. Despite significant scientific efforts, the prognosis for GBM remains very poor, even after intensive treatment with surgery, radiation, and chemotherapy. Efficient GBM management still requires the invention of innovative treatment strategies. There is a strong necessity to complete cancer in vitro studies and in vivo studies to properly evaluate the mechanisms of tumor progression within the complex TME. In recent years, the animal models used to study GBM tumors have evolved, achieving highly invasive GBM models able to provide key information on the molecular mechanisms of GBM onset. At present, the most commonly used animal models in GBM research are represented by mammalian models, such as mouse and canine ones. However, the latter present several limitations, such as high cost and time-consuming management, making them inappropriate for large-scale anticancer drug evaluation. In recent years, the zebrafish (Danio rerio) model has emerged as a valuable tool for studying GBM. It has shown great promise in preclinical studies due to numerous advantages, such as its small size, its ability to generate a large cohort of genetically identical offspring, and its rapid development, permitting more time- and cost-effective management and high-throughput drug screening when compared to mammalian models. Moreover, due to its transparent nature in early developmental stages and genetic and anatomical similarities with humans, it allows for translatable brain cancer research and related genetic screening and drug discovery. For this reason, the aim of the present review is to highlight the potential of relevant transgenic and xenograft zebrafish models and to compare them to the traditionally used animal models in GBM research.

Deciphering the impact of circRNA-mediated autophagy on tumor therapeutic resistance: a novel perspective

Cancer therapeutic resistance remains a significant challenge in the pursuit of effective treatment strategies. Circular RNAs (circRNAs), a class of non-coding RNAs, have recently emerged as key regulators of various biological processes, including cancer progression and drug resistance. This review highlights the emerging role of circRNAs-mediated autophagy in cancer therapeutic resistance, a cellular process that plays a dual role in cancer by promoting both cell survival and death. Increasing evidence suggests that circRNAs can modulate autophagy pathways, thereby influencing the response of cancer cells to therapeutic agents. In this context, the intricate interplay between circRNAs, autophagy, and therapeutic resistance is explored. Various mechanisms are discussed through which circRNAs can impact autophagy, including direct interactions with autophagy-related genes, modulation of signaling pathways, and cross-talk with other non-coding RNAs. Furthermore, the review delves into specific examples of how circRNA-mediated autophagy regulation can contribute to resistance against chemotherapy and radiotherapy. Understanding these intricate molecular interactions provides valuable insights into potential strategies for overcoming therapeutic resistance in cancer. Exploiting circRNAs as therapeutic targets or utilizing them as diagnostic and predictive biomarkers opens new avenues for developing personalized treatment approaches. In summary, this review underscores the importance of circRNA-mediated autophagy in cancer therapeutic resistance and proposes future directions for research in this exciting and rapidly evolving field.

Tumor-derived extracellular vesicles regulate macrophage polarization: role and therapeutic perspectives

Extracellular vesicles (EVs) are important cell-to-cell communication mediators. This paper focuses on the regulatory role of tumor-derived EVs on macrophages. It aims to investigate the causes of tumor progression and therapeutic directions. Tumor-derived EVs can cause macrophages to shift to M1 or M2 phenotypes. This indicates they can alter the M1/M2 cell ratio and have pro-tumor and anti-inflammatory effects. This paper discusses several key points: first, the factors that stimulate macrophage polarization and the cytokines released as a result; second, an overview of EVs and the methods used to isolate them; third, how EVs from various cancer cell sources, such as hepatocellular carcinoma, colorectal carcinoma, lung carcinoma, breast carcinoma, and glioblastoma cell sources carcinoma, promote tumor development by inducing M2 polarization in macrophages; and fourth, how EVs from breast carcinoma, pancreatic carcinoma, lungs carcinoma, and glioblastoma cell sources carcinoma also contribute to tumor development by promoting M2 polarization in macrophages. Modified or sourced EVs from breast, pancreatic, and colorectal cancer can repolarize M2 to M1 macrophages. This exhibits anti-tumor activities and offers novel approaches for tumor treatment. Therefore, we discovered that macrophage polarization to either M1 or M2 phenotypes can regulate tumor development. This is based on the description of altering macrophage phenotypes by vesicle contents.

Deciphering Glioblastoma: Fundamental and Novel Insights into the Biology and Therapeutic Strategies of Gliomas

Gliomas constitute a diverse and complex array of tumors within the central nervous system (CNS), characterized by a wide range of prognostic outcomes and responses to therapeutic interventions. This literature review endeavors to conduct a thorough investigation of gliomas, with a particular emphasis on glioblastoma (GBM), beginning with their classification and epidemiological characteristics, evaluating their relative importance within the CNS tumor spectrum. We examine the immunological context of gliomas, unveiling the intricate immune environment and its ramifications for disease progression and therapeutic strategies. Moreover, we accentuate critical developments in understanding tumor behavior, focusing on recent research breakthroughs in treatment responses and the elucidation of cellular signaling pathways. Analyzing the most novel transcriptomic studies, we investigate the variations in gene expression patterns in glioma cells, assessing the prognostic and therapeutic implications of these genetic alterations. Furthermore, the role of epigenetic modifications in the pathogenesis of gliomas is underscored, suggesting that such changes are fundamental to tumor evolution and possible therapeutic advancements. In the end, this comparative oncological analysis situates GBM within the wider context of neoplasms, delineating both distinct and shared characteristics with other types of tumors.

Epigenetic regulation of mRNA mediates the phenotypic plasticity of cancer cells during metastasis and therapeutic resistance (Review)

Plasticity, the ability of cancer cells to transition between differentiation states without genomic alterations, has been recognized as a major source of intratumoral heterogeneity. It has a crucial role in cancer metastasis and treatment resistance. Thus, targeting plasticity holds tremendous promise. However, the molecular mechanisms of plasticity in cancer cells remain poorly understood. Several studies found that mRNA, which acts as a bridge linking the genetic information of DNA and protein, has an important role in translating genotypes into phenotypes. The present review provided an overview of the regulation of cancer cell plasticity occurring via changes in the transcription and editing of mRNAs. The role of the transcriptional regulation of mRNA in cancer cell plasticity was discussed, including DNA‑binding transcriptional factors, DNA methylation, histone modifications and enhancers. Furthermore, the role of mRNA editing in cancer cell plasticity was debated, including mRNA splicing and mRNA modification. In addition, the role of non‑coding (nc)RNAs in cancer plasticity was expounded, including microRNAs, long intergenic ncRNAs and circular RNAs. Finally, different strategies for targeting cancer cell plasticity to overcome metastasis and therapeutic resistance in cancer were discussed.

Glioblastoma research on zebrafish xenograft models: a systematic review

Glioblastoma (GBM) constitutes the most common primary brain tumor in adults. The challenges in GBM therapeutics have shed light on zebrafish used as a promising animal model for preclinical GBM xenograft studies without a standardized methodology. This systematic review aims to summarize the advances in zebrafish GBM xenografting, compare research protocols to pinpoint advantages and underlying limitations, and designate the predominant xenografting parameters. Based on the PRISMA checklist, we systematically searched PubMed, Scopus, and ZFIN using the keywords "glioblastoma," "xenotransplantation," and "zebrafish" for papers published from 2005 to 2022, available in English. 46 articles meeting the review criteria were examined for the zebrafish strain, cancer cell line, cell labeling technique, injected cell number, time and site of injection, and maintenance temperature. Our review designated that AB wild-type zebrafish, Casper transparent mutants, transgenic Tg(fli1:EGFP), or crossbreeding of these predominate among the zebrafish strains. Orthotopic transplantation is more commonly employed. A number of 50-100 cells injected at 48 h post-fertilization in high density and low infusion volume is considered as an effective xenografting approach. U87 cells are used for GBM angiogenesis studies, U251 for GBM proliferation studies, and patient-derived xenograft (PDX) to achieve clinical relevance. Gradual acclimatization to 32-33 °C can partly address the temperature differential between the zebrafish and the GBM cells. Zebrafish xenograft models constitute valuable tools for preclinical studies with clinical relevance regarding PDX. The GBM xenografting research requires modification based on the objective of each research team. Automation and further optimization of the protocol parameters could scale up the anticancer drug trials.

Tumor-derived extracellular vesicles: how they mediate glioma immunosuppression

Gliomas, the most common malignant brain tumor, present a grim prognosis despite available treatments such as surgical resection, temozolomide (TMZ) therapy, and radiation therapy. This is due to their aggressive growth, high level of immunosuppression, and the blood-brain barrier (BBB), which obstruct the effective exchange of therapeutic drugs. Gliomas can significantly affect differentiation and function of immune cells by releasing extracellular vesicles (EVs), resulting in a systemic immunosuppressive state and a highly immunosuppressive microenvironment. In the tumor immune microenvironment (TIME), the primary immune cells are regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSCs), and tumor-associated macrophages (TAMs). In particular, glioma-associated TAMs are chiefly composed of monocyte-derived macrophages and brain-resident microglia. These cells partially exhibit characteristics of a pro-tumorigenic, anti-inflammatory M2-type. Glioma-derived EVs can hijack TAMs to differentiate into tumor-supporting phenotypes or directly affect the maturation of peripheral blood monocytes (PBMCs) and promote the activation of MDSCs. In addition, EVs impair the ability of dendritic cells (DCs) to process antigens, subsequently hindering the activation of lymphocytes. EVs also impact the proliferation, differentiation, and activation of lymphocytes. This is primarily evident in the overall reduction of CD4 + helper T cells and CD8 + T cells, coupled with a relative increase in Tregs, which possess immunosuppressive characteristics. This study investigates thoroughly how tumor-derived EVs impair the function of immune cells and enhance immunosuppression in gliomas, shedding light on their potential implications for immunotherapy strategies in glioma treatment.

Exosomal non-coding RNAs in glioma progression: insights into tumor microenvironment dynamics and therapeutic implications

Gliomas are the most common and deadly types of brain tumors, known for their extensive genetic and epigenetic variability, which poses considerable challenges for pharmacological treatment. Glioma heterogeneity is also related to their intricate and dynamic tumor microenvironment (TME), which comprises a diverse array of cell types, including immune cells, vascular cells, glial cells, and neural precursors, collectively influencing tumor behavior and progression. A pivotal aspect of this intercellular communication relies on the exchange of extracellular vesicles (EVs), which contain and transfer complex molecular cargoes typical of their cells of origin, such as proteins, lipids, carbohydrates, metabolites, and non-coding RNAs (ncRNAs), that encompass microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). Glioma cells actively release EVs loaded with specific ncRNAs that can target genes and other ncRNAs in recipient cells residing within the TME. Among these recipient cells, prominent players include tumor-associated macrophages and microglia (TAMs), non-neoplastic astrocytes and endothelial cells. The intricate interplay between EVs derived from glioma cells and these recipient cells significantly contributes to the establishment of a tumor-permissive microenvironment, promoting tumor cell proliferation, migration, angiogenesis, and invasion, by targeting various downstream pathways. This review critically examines the current understanding of the intricate interplay between glioma, exosomal ncRNAs, and various components of the glioma TME. By shedding light on the roles of ncRNAs in mediating intercellular communication, this review underscores their significance in orchestrating TME transformation and highlights their potential as novel therapeutic targets for effectively tackling glioma progression.

The Glioblastoma CircularRNAome

Glioblastoma remains one of the most aggressive cancers of the brain, warranting new methods for early diagnosis and more efficient treatment options. Circular RNAs (circRNAs) are rather new entities with increased stability compared to their linear counterparts that interact with proteins and act as microRNA sponges, among other functions. Herein, we provide a critical overview of the recently described glioblastoma-related circRNAs in the literature, focusing on their roles on glioblastoma cancer cell proliferation, survival, migration, invasion and metastasis, metabolic reprogramming, and therapeutic resistance. The main roles of circRNAs in regulating cancer processes are due to their regulatory roles in essential oncogenic pathways, including MAPK, PI3K/AKT/mTOR, and Wnt, which are influenced by various circRNAs. The present work pictures the wide implication of circRNAs in glioblastoma, thus highlighting their potential as future biomarkers and therapeutic targets/agents.

Advances in the study of the molecular biological mechanisms of radiation-induced brain injury

Radiation therapy is one of the most commonly used treatments for head and neck cancers, but it often leads to radiation-induced brain injury. Patients with radiation-induced brain injury have a poorer quality of life, and no effective treatments are available. The pathogenesis of this condition is unknown. This review summarizes the molecular biological mechanism of radiation-induced brain injury and provides research directions for future studies. The molecular mechanisms of radiation-induced brain injury are diverse and complex. Radiation-induced chronic neuroinflammation, destruction of the blood-brain barrier, oxidative stress, neuronal damage, and physiopathological responses caused by specific exosome secretion lead to radiation-induced brain injury.

Signal-transducing adaptor protein 1 (STAP1) in microglia promotes the malignant progression of glioma

BACKGROUND

Glioma is the most malignant primary brain tumor with a poor survival time. The tumour microenvironment, especially glioma-associated microglia/macrophages (GAMs), plays an important role in the pathogenesis of glioma. Currently, microglia (CD11b+/CD45Low) and macrophages (CD11b+/CD45High) are distinguished as distinct cell types due to their different origins. Moreover, signal-transducing adaptor protein 1 (STAP1) plays a role in tumourigenesis and immune responses. However, to date, no studies have been reported on STAP1 in GAMs.

METHODS

The Cancer Genome Atlas and Chinese Glioma Genome Atlas databases were used to investigate the association between STAP1 mRNA levels and clinical parameters (grades, mutations in isocitrate dehydrogenase, and overall survival). RNA-sequencing, qRT-PCR, Western blotting, immunohistochemistry and immunofluorescence analyses were performed to detect the expression level of STAP1 and related proteins. BV-2 cells were used to construct a STAP1-overexpressing cell line. Phagocytosis of BV-2 cells was assessed by flow cytometry and fluorescence microscopy. C57BL/6 mice were used to establish orthotopic and subcutaneous glioma mouse models. Glioma growth was monitored by bioluminescence imaging.

RESULTS

STAP1 expression in glioma-associated microglia is positively correlated with the degree of malignancy and poor prognosis of glioma. Moreover, STAP1 may promote M2-like polarisation by increasing ARG1 expression and inhibiting microglial phagocytosis of microglia. Increased ARG1 may be associated with the IL-6/STAT3 pathway. Impaired phagocytosis may be associated with decreased cofilin and filopodia.

CONCLUSION

STAP1 is positively associated with the degree of glioma malignancy and may represent a potential novel therapeutic target for glioma.

Recent advances of exosomal circRNAs in cancer and their potential clinical applications

Circular RNA (circRNA) is a type of non-coding RNA that forms a covalently closed, uninterrupted loop. The expression of circRNA differs among cell types and tissues, and various circRNAs are aberrantly expressed in a variety of diseases, including cancer. Aberrantly expressed circRNAs contribute to disease progression by acting as microRNA sponges, functional protein sponges, or novel templates for protein translation. Recent studies have shown that circRNAs are enriched in exosomes. Exosomes are spherical bilayer vesicles released by cells into extracellular spaces that mediate intercellular communication by delivering cargoes. These cargoes include metabolites, proteins, lipids, and RNA molecules. Exosome-mediated cell-cell or cell-microenvironment communications influence the progression of carcinogenesis by regulating cell proliferation, angiogenesis, metastasis as well as immune escape. In this review, we summarize the current knowledge about exosomal circRNAs in cancers and discuss their specific functions in tumorigenesis. Additionally, we discuss the potential value of exosomal circRNAs as diagnostic biomarkers and the potential applications of exosomal circRNA-based cancer therapy.

Suppression of microglial Ccl2 reduces neuropathic pain associated with chronic spinal compression

Introduction

Chronic spinal compression is a common complication of spinal cord injury (SCI), which can lead to spinal stenosis or herniated discs. The ensuing neuropathic pain is often associated with the activation of microglia. In this investigation, our objective was to explore whether modifying the levels of chemokine (C-C motif) ligand 2 (Ccl2) in microglia could alleviate neuropathic pain resulting from chronic spinal compression.

Methods

We used a public database to look for major altered gene associated in a SCI model established in rats. We then employed adeno-associated virus (AAV) vectors, expressing siRNA for the identified significantly altered gene under a microglia-specific TMEM119 promoter. We also tested the impact of this treatment in microglia in vivo on the severity of chronic spinal compression and associated pain using a ttw mouse model for progressive spinal compression.

Results

We identified chemokine (C-C motif) ligand 2 (Ccl2) as the primary gene altered in microglia within a rat SCI model, utilizing a public database. Microglial Ccl2 levels were then found to be significantly elevated in disc specimens from SCI patients diagnosed with chronic spinal compression and strongly correlated with the Thompson classification of the degeneration level and pain score. Depletion of Ccl2 in microglia-specific TMEM119 promoter were developed to transfect mouse microglia in vitro, resulting in a proinflammatory to anti-inflammatory phenotypic adaption. In vivo depletion of Ccl2 in microglia mitigated the severity of chronic spinal compression and related pain in ttw mice, likely due to significant changes in pain-associated cytokines and factors.

Conclusion

Disc microglia expressing high levels of Ccl2 may contribute to chronic spinal compression and SCI-associated pain. Therapeutically targeting Ccl2 in microglia could offer a potential avenue for treating chronic spinal compression and SCI-associated pain.

Circular RNA circ_0000741/miR-379-5p/TRIM14 signaling axis promotes HDAC inhibitor (SAHA) tolerance in glioblastoma

BACKGROUND

Histone deacetylase (HDAC) inhibitor-based therapeutic drug tolerance is a major obstacle to glioblastoma (GBM) treatment. Meanwhile, non-coding RNAs have been reported to be involved in the regulation of HDAC inhibitor (SAHA) tolerance in some human tumors. However, the relationship between circular RNAs (circRNAs) and SAHA tolerance is still unknown. Herein, we explored the role and mechanism of circ_0000741 on SAHA tolerance in GBM.

METHODS

Circ_0000741, microRNA-379-5p (miR-379-5p), and tripartite motif-containing 14 (TRIM14) level were detected by real-time quantitative polymerase chain reaction (RT-qPCR). (4-5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), 5-ethynyl-2'-deoxyuridine (EdU), Colony formation, flow cytometry, and transwell assays were used to detect SAHA tolerance, proliferation, apoptosis, and invasion in SAHA-tolerant GBM cells. Western blot analysis of protein levels of E-cadherin, N-cadherin, and TRIM14. After Starbase2.0 analysis, the binding between miR-379-5p and circ_0000741 or TRIM14 was proved using a dual-luciferase reporter. The role of circ_0000741 on drug tolerance was assessed using a xenograft tumor model in vivo.

RESULTS

Circ_0000741 and TRIM14 were upregulated, and miR-379-5p was reduced in SAHA-tolerant GBM cells. Furthermore, circ_0000741 absence reduced SAHA tolerance, suppressed proliferation, invasion, and induced apoptosis in SAHA-tolerant GBM cells. Mechanistically, circ_0000741 might affect TRIM14 content via sponging miR-379-5p. Besides, circ_0000741 silencing enhanced the drug sensitivity of GBM in vivo.

CONCLUSION

Circ_0000741 might accelerate SAHA tolerance by regulating the miR-379-5p/TRIM14 axis, which provided a promising therapeutic target for GBM treatment.

Exosomal circRNAs as promising liquid biopsy biomarkers for glioma

Liquid biopsy strategies enable the noninvasive detection of changes in the levels of circulating biomarkers in body fluid samples, providing an opportunity to diagnose, dynamically monitor, and treat a range of diseases, including cancers. Glioma is among the most common forms of intracranial malignancy, and affected patients exhibit poor prognostic outcomes. As such, diagnosing and treating this disease in its early stages is critical for optimal patient outcomes. Exosomal circular RNAs (circRNAs) are involved in both the onset and progression of glioma. Both the roles of exosomes and methods for their detection have received much attention in recent years and the detection of exosomal circRNAs by liquid biopsy has significant potential for monitoring dynamic changes in glioma. The present review provides an overview of the circulating liquid biopsy biomarkers associated with this cancer type and the potential application of exosomal circRNAs as tools to guide the diagnosis, treatment, and prognostic evaluation of glioma patients during disease progression.

Microglia and Brain Macrophages as Drivers of Glioma Progression

Evidence is accumulating that the tumour microenvironment (TME) has a key role in the progression of gliomas. Non-neoplastic cells in addition to the tumour cells are therefore finding increasing attention. Microglia and other glioma-associated macrophages are at the centre of this interest especially in the context of therapeutic considerations. New ideas have emerged regarding the role of microglia and, more recently, blood-derived brain macrophages in glioblastoma (GBM) progression. We are now beginning to understand the mechanisms that allow malignant glioma cells to weaken microglia and brain macrophage defence mechanisms. Surface molecules and cytokines have a prominent role in microglia/macrophage-glioma cell interactions, and we discuss them in detail. The involvement of exosomes and microRNAs forms another focus of this review. In addition, certain microglia and glioma cell pathways deserve special attention. These "synergistic" (we suggest calling them "Janus") pathways are active in both glioma cells and microglia/macrophages where they act in concert supporting malignant glioma progression. Examples include CCN4 (WISP1)/Integrin α6β1/Akt and CHI3L1/PI3K/Akt/mTOR. They represent attractive therapeutic targets.