Mesenchymal stem cells, as glioma exosomal immunosuppressive signal multipliers, enhance MDSCs immunosuppressive activity through the miR-21/SP1/DNMT1 positive feedback loop.

BACKGROUND: The immunosuppressive microenvironment in glioma induces immunotherapy resistance and is associated with poor prognosis. Glioma-associated mesenchymal stem cells (GA-MSCs) play an important role in the formation of the immunosuppressive microenvironment, but the mechanism is still not clear. RESULTS: We found that GA-MSCs promoted the expression of CD73, an ectonucleotidase that drives immunosuppressive microenvironment maintenance by generating adenosine, on myeloid-derived suppressor cells (MDSCs) through immunosuppressive exosomal miR-21 signaling. This process was similar to the immunosuppressive signaling mediated by glioma exosomal miR-21 but more intense. Further study showed that the miR-21/SP1/DNMT1 positive feedback loop in MSCs triggered by glioma exosomal CD44 upregulated MSC exosomal miR-21 expression, amplifying the glioma exosomal immunosuppressive signal. Modified dendritic cell-derived exosomes (Dex) carrying miR-21 inhibitors could target GA-MSCs and reduce CD73 expression on MDSCs, synergizing with anti-PD-1 monoclonal antibody (mAb). CONCLUSIONS: Overall, this work reveals the critical role of MSCs in the glioma microenvironment as signal multipliers to enhance immunosuppressive signaling of glioma exosomes, and disrupting the positive feedback loop in MSCs with modified Dex could improve PD-1 blockade therapy.

EWSR1-induced circNEIL3 promotes glioma progression and exosome-mediated macrophage immunosuppressive polarization via stabilizing IGF2BP3.

BACKGROUND: Gliomas are the most common malignant primary brain tumours with a highly immunosuppressive tumour microenvironment (TME) and poor prognosis. Circular RNAs (circRNA), a newly found type of endogenous noncoding RNA, characterized by high stability, abundance, conservation, have been shown to play an important role in the pathophysiological processes and TME remodelling of various tumours. METHODS: CircRNA sequencing analysis was performed to explore circRNA expression profiles in normal and glioma tissues. The biological function of a novel circRNA, namely, circNEIL3, in glioma development was confirmed both in vitro and in vivo. Mechanistically, RNA pull-down, mass spectrum, RNA immunoprecipitation (RIP), luciferase reporter, and co-immunoprecipitation assays were conducted. RESULTS: We identified circNEIL3, which could be cyclized by EWS RNA-binding protein 1(EWSR1), to be upregulated in glioma tissues and to correlate positively with glioma malignant progression. Functionally, we confirmed that circNEIL3 promotes tumorigenesis and carcinogenic progression of glioma in vitro and in vivo. Mechanistically, circNEIL3 stabilizes IGF2BP3 (insulin-like growth factor 2 mRNA binding protein 3) protein, a known oncogenic protein, by preventing HECTD4-mediated ubiquitination. Moreover, circNEIL3 overexpression glioma cells drives macrophage infiltration into the tumour microenvironment (TME). Finally, circNEIL3 is packaged into exosomes by hnRNPA2B1 and transmitted to infiltrated tumour associated macrophages (TAMs), enabling them to acquire immunosuppressive properties by stabilizing IGF2BP3 and in turn promoting glioma progression. CONCLUSIONS: This work reveals that circNEIL3 plays a nonnegligible multifaceted role in promoting gliomagenesis, malignant progression and macrophage tumour-promoting phenotypes polarization, highlighting that circNEIL3 is a potential prognostic biomarker and therapeutic target in glioma.

miR-3184-3p enriched in cerebrospinal fluid exosomes contributes to progression of glioma and promotes M2-like macrophage polarization.

Liquid biopsy is a novel strategy for tumour diagnosis. The contents of cerebrospinal fluid (CSF) exosomes could reflect glioma status, hence sampling exosomes from CSF is a means of liquid biopsy for glioma. However, few studies have focused on the function of microRNAs in CSF exosomes. In this study, we found that miR-3184-3p was enriched in CSF exosomes in glioma patients and was downregulated after tumour resection. We found that miR-3184 facilitates glioma progression in two ways. On the one hand, miR-3184 directly promotes proliferation, migration, and invasion while inhibiting apoptosis in glioma. On the other hand, miR-3184 in glioma-derived exosomes polarizes macrophages to an M2-like phenotype, which further aggravates tumour progression. Overall, the current findings uncovered a new mechanism and highlighted the significant role of miR-3184 in glioma progression. Furthermore, exosomal miR-3184 could be a considerable factor with potential applications in glioma diagnosis and treatment in the future.

Exosomal miR-1246 from glioma patient body fluids drives the differentiation and activation of myeloid-derived suppressor cells.

Glioma is a heterogeneous cellular environment in which immune cells play critical roles in tumor progression. Myeloid-derived suppressor cells (MDSCs) contribute to the formation of the immunosuppressive microenvironment of glioma; however, how glioma cells interact with MDSCs and how this interaction affects the function of other immune cells are unclear. Glioma cells can systemically communicate with immune cells via the secretion of exosomes, which contain microRNAs (miRNAs). Leveraging miRNA sequencing of exosomes, we identified enrichment of miR-1246 in glioma-derived exosomes and exosomes isolated from the cerebrospinal fluid (CSF) of glioma patients. We demonstrated that miR-1246 drives the differentiation and activation of MDSCs in a dual specificity phosphatase 3 (DUSP3)/extracellular signal­regulated kinase (ERK)-dependent manner. In addition, postoperative CSF exosomal miR-1246 expression was found to be associated with the glioma recurrence rate. Hypoxia, a well-recognized feature of the glioblastoma microenvironment, increased miR-1246 levels in glioma-derived exosomes by enhancing miR-1246 transcription and selective packaging via upregulation of POU class 5 homeobox 1 (POU5F1) and heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1). Importantly, we identified a mechanism of 2-methoxyestradiol, a microtubule inhibitor currently undergoing clinical trials for glioblastoma. 2-Methoxyestradiol suppresses MDSC activation by inhibiting hypoxia-driven exosomal miR-1246 expression in glioma cells and PD-L1 expression in MDSCs.

Glioma exosomes mediate the expansion and function of myeloid-derived suppressor cells through microRNA-29a/Hbp1 and microRNA-92a/Prkar1a pathways.

Myeloid-derived suppressor cells (MDSCs) play a pivotal role in mediating the formation of an immunosuppressive environment and assisting tumors in evading the host immune response. However, the mechanism through which tumors manipulate the differentiation and function of MDSCs remains unclear. Here, we report that hypoxia-induced glioma cells can stimulate the differentiation of functional MDSCs by transferring exosomal miR-29a and miR-92a to MDSCs. Our results showed that glioma-derived exosomes (GEXs) can enhance the differentiation of functional MDSCs both in vitro and in vivo, and hypoxia-induced GEXs (H-GEXs) demonstrated a stronger MDSCs induction ability than did normoxia-induced GEXs (N-GEXs). A subsequent miRNA sequencing analysis of N-GEXs and H-GEXs revealed that hypoxia-induced exosomal miR-29a and miR-92a expression induced the propagation of MDSCs. miR-29a and miR-92a activated the proliferation and function of MDSCs by targeting high-mobility group box transcription factor 1 (Hbp1) and protein kinase cAMP-dependent type I regulatory subunit alpha (Prkar1a), respectively. Altogether, the results of our study provide new insights into the role of glioma exosomal miRNAs in mediating the formation of immunosuppressive microenvironments in tumors and elucidate the underlying exosomal miR-29a/miR-92a-based regulatory mechanism responsible for the modulation of functional MDSC induction.

Efficient EVs separation and detection by an alumina-nanochannel-array-membrane integrated microfluidic chip and an antibody barcode biochip.

BACKGROUND: Small endosome-derived lipid nanovesicles (30-200 nm) are actively secreted by living cells and serve as pivotal biomarkers for early cancer diagnosis. However, the study of extracellular vesicles (EVs) requires isolation and purification from various body fluids. Although traditional EVs isolation and detection technologies are mature, they usually require large amount of sample, consumes long-time, and have relatively low-throughput. How to efficiently isolate, purify and detect these structurally specific EVs from body fluids with high-throughput remains a great challenge in in vitro diagnostics and clinical research. RESULTS: Herein, we suggest a nanosized microfluidic device for efficient and economical EVs filtration based on an alumina nanochannel array membrane. We evaluated the filtration device performance of alumina membranes with different diameters and found that an optimized chamber array with a hydrophilic-treated channel diameter of 90 nm could realize a filtration efficiency of up to 82% without any assistance from chemical or physical separation methods. Importantly, by integrating meticulously designed multichannel microfluidic biochips, EVs can be captured in-situ and monitored by antibody barcode biochip. The proposed filtration chip together with the high-throughput detection chip were capable of filtration of a few tens of µL samples and recognition of different phonotypes. The practical filtration and detection of EVs from clinical samples demonstrated the high performance of the device. SIGNIFICANT: Overall, this work provides a cost-effective, highly efficient and automated EVs filtration chip and detection dual-function integrated chip platform, which can directly separate EVs from serum or cerebrospinal fluid with an efficiency of 82% and conduct in-situ detection. This small fluidic device can provide a powerful tool for highly efficient identifying and analyzing EVs, presenting great application potential in clinical detection.

SPI1-mediated MIR222HG transcription promotes proneural-to-mesenchymal transition of glioma stem cells and immunosuppressive polarization of macrophages.

Background: Glioma stem cells (GSCs) are a key factor in glioblastoma (GBM) development and treatment resistance. GSCs can be divided into the mesenchymal (MES) and proneural (PN) subtypes, and these two subtypes of GSCs can undergo interconversion under certain conditions. MES GSCs have higher malignancy and radioresistance and are closely associated with an immunosuppressive microenvironment. Long noncoding RNAs (lncRNAs) play a broad role in GBM, while the role of GSCs subtype remains unknown. Methods: We performed RNA sequencing to explore the lncRNA expression profile in MES- and PN-subtype GBM tissues. The biological function of a host gene-MIR222HG-in GBM development was confirmed in vitro and in vivo. Specifically, RNA sequencing, RNA pulldown, mass spectrometry, RIP, ChIP, luciferase reporter assays and Co-IP were performed. Results: MIR222HG, the expression of which can be induced by SPI1, has high levels in MES GBM tissues. Functionally, we demonstrated that MIR222HG promotes the MES transition and radioresistance in GSCs in vivo and in vitro. Mechanistically, MIR222HG can bind to the YWHAE/HDAC5 complex to promote the MES transition of GSCs through H4 deacetylation. Moreover, cotranscribed miR221 and miR222 can be delivered to macrophages via exosomes to target SOCS3, causing immunosuppressive polarization. Finally, PLX-4720 sensitivity is associated with SPI1 expression and acts on MES GSCs to enhance radiosensitivity. Conclusions: This study demonstrates that targeting SPI1 to block transcription of the MIR222HG cluster helps to reduce radioresistance and combat the immunosuppressive microenvironment in GBM. PLX-4720 is a potential GBM drug and radiosensitizer.

Hypoxia-induced circADAMTS6 in a TDP43-dependent manner accelerates glioblastoma progression via ANXA2/ NF-κB pathway.

Circular RNAs (circRNAs) play important roles in the malignant progression of tumours. Herein, we identified an unreported circRNA (hsa-circ-0072688, also named circADAMTS6) that is specifically upregulated in the hypoxic microenvironment of glioblastoma and closely correlated with poor prognosis of gliblastoma patients. We found that circADAMTS6 promotes the malignant progression of glioblastoma by promoting cell proliferation and inhibiting apoptosis. Mechanistically, the hypoxic tumour microenvironment upregulates circADAMTS6 expression through transcription factor activator protein 1 (AP-1) and RNA-binding protein TAR DNA-binding protein 43 (TDP43). Moreover, circADAMTS6 accelerates glioblastoma progression by recruiting and stabilising annexin A2 (ANXA2) in a proteasomes-dependent manner. Furthermore, we found T-5224 (AP-1 inhibitor) treatment induces downregulation of circADAMTS6 and then inhibits tumour growth. In conclusion, our findings highlight the important role of the circADAMTS6/ANXA2 axis based on hypoxic microenvironment in glioblastoma progression, as well as its regulation in NF-κB pathway. Targeting circADAMTS6 is thus expected to become a novel therapeutic strategy for glioblastoma.

Glioblastoma upregulates SUMOylation of hnRNP A2/B1 to eliminate the tumor suppressor miR-204-3p, accelerating angiogenesis under hypoxia.

Glioma is the most common malignant tumor of the central nervous system in adults. The tumor microenvironment (TME) is related to poor prognosis in glioma patients. Glioma cells could sort miRNA into exosomes to modify TME. And hypoxia played an important role in this sorting process, but the mechanism is not clear yet. Our study was to find miRNAs sorted into glioma exosomes and reveal the sorting process. Sequencing analysis of glioma patients cerebrospinal fluid (CSF) and tissue showed that miR-204-3p tends to be sorted into exosomes. miR-204-3p suppressed glioma proliferation through the CACNA1C/MAPK pathway. hnRNP A2/B1 can accelerate exosome sorting of miR-204-3p by binding a specific sequence. Hypoxia plays an important role in exosome sorting of miR-204-3p. Hypoxia can upregulate miR-204-3p by upregulating the translation factor SOX9. Hypoxia promotes the transfer of hnRNP A2/B1 to the cytoplasm by upregulating SUMOylation of hnRNP A2/B1 to eliminate miR-204-3p. Exosomal miR-204-3p promoted tube formation of vascular endothelial cells through the ATXN1/STAT3 pathway. The SUMOylation inhibitor TAK-981 can inhibit the exosome-sorting process of miR-204-3p to inhibit tumor growth and angiogenesis. This study revealed that glioma cells can eliminate the suppressor miR-204-3p to accelerate angiogenesis under hypoxia by upregulating SUMOylation. The SUMOylation inhibitor TAK-981 could be a potential drug for glioma. This study revealed that glioma cells can eliminate the suppressor miR-204-3p to accelerate angiogenesis under hypoxia by upregulating SUMOylation. The SUMOylation inhibitor TAK-981 could be a potential drug for glioma.

The risk of osteopenia in premenopausal women with various sellar tumors.

OBJECTIVE: Patients with prolactinoma seem to be at high risk for osteopenia. However, whether patients with various pathological sellar tumors have risk for osteopenia remains unclear. The aim of the present study is to assess the bone mass alteration in patients with various sellar tumors and further to investigate the risk factors of bone mass alteration. MATERIALS AND METHODS: 65 premenopausal female patients with diverse sellar tumors and 325 normal controls were enrolled in this study. Bone mineral density (BMD) of lumbar spine and comprehensive endocrinological evaluations were undergone. RESULTS: Compared to the matched controls, BMD of patients with prolactinoma or craniopharyngioma significantly decreased. Patients with sellar meningioma and nonfunctioning adenoma are with a decreasing tendency and patients with growth hormone-secreting adenoma are with an increasing tendency compared to controls. Univariate and multivariate regression analysis indicated that the bone loss in prolactinomas was significantly correlated to disease duration and hypogonadism. CONCLUSION: In the premenopausal women, patients with prolactinoma or craniopharyngioma are often accompanied with osteopenia or osteoporosis, and disease duration and hypogonadism are the risk factors of bone loss in prolactinoma. Continuous surveillance of BMD is recommended in patients with meningioma or nonfunctioning adenoma.

Identification and validation of SNHG gene signature to predict malignant behaviors and therapeutic responses in glioblastoma.

Glioblastoma (GBM) patients exhibit high mortality and recurrence rates despite multimodal therapy. Small nucleolar RNA host genes (SNHGs) are a group of long noncoding RNAs that perform a wide range of biological functions. We aimed to reveal the role of SNHGs in GBM subtypes, cell infiltration into the tumor microenvironment (TME), and stemness characteristics. SNHG interaction patterns were determined based on 25 SNHGs and systematically correlated with GBM subtypes, TME and stemness characteristics. The SNHG interaction score (SNHGscore) model was generated to quantify SNHG interaction patterns. The high SNHGscore group was characterized by a poor prognosis, the mesenchymal (MES) subtype, the infiltration of suppressive immune cells and a differentiated phenotype. Further analysis indicated that high SNHGscore was associated with a weaker response to anti-PD-1/L1 immunotherapy. Tumor cells with high SNHG scores were more sensitive to drugs targeting the EGFR and ERK-MAPK signaling pathways. Finally, we assessed SNHG interaction patterns in multiple cancers to verify their universality. This is a novel and comprehensive study that provides targeted therapeutic strategies based on SNHG interactions. Our work highlights the crosstalk and potential clinical utility of SNHG interactions in cancer therapy.

Synchronous Disintegration of Ferroptosis Defense Axis via Engineered Exosome-Conjugated Magnetic Nanoparticles for Glioblastoma Therapy.

Glioblastoma (GBM) is one of the most fatal central nervous system tumors and lacks effective or sufficient therapies. Ferroptosis is a newly discovered method of programmed cell death and opens a new direction for GBM treatment. However, poor blood-brain barrier (BBB) penetration, reduced tumor targeting ability, and potential compensatory mechanisms hinder the effectiveness of ferroptosis agents during GBM treatment. Here, a novel composite therapeutic platform combining the magnetic targeting features and drug delivery properties of magnetic nanoparticles with the BBB penetration abilities and siRNA encapsulation properties of engineered exosomes for GBM therapy is presented. This platform can be enriched in the brain under local magnetic localization and angiopep-2 peptide-modified engineered exosomes can trigger transcytosis, allowing the particles to cross the BBB and target GBM cells by recognizing the LRP-1 receptor. Synergistic ferroptosis therapy of GBM is achieved by the combined triple actions of the disintegration of dihydroorotate dehydrogenase and the glutathione peroxidase 4 ferroptosis defense axis with Fe3 O4 nanoparticle-mediated Fe2+ release. Thus, the present findings show that this system can serve as a promising platform for the treatment of glioblastoma.

Comprehensive Analysis of the Tumor Immune Microenvironment Landscape in Glioblastoma Reveals Tumor Heterogeneity and Implications for Prognosis and Immunotherapy.

Background: Glioblastoma (GBM) is a fatal brain tumor with no effective treatment. The specific GBM tumor immune microenvironment (TIME) may contribute to resistance to immunotherapy, a tumor therapy with great potential. Thus, an in-depth understanding of the characteristics of tumor-infiltrating immune cells is essential for exploring biomarkers in GBM pathogenesis and immunotherapy. Methods: We estimated the relative abundances of 25 immune cell types in 796 GBM samples using single sample gene set enrichment analysis (ssGSEA). Unsupervised clustering was used to identify different GBM-associated TIME immune cell infiltration (GTMEI) patterns. The GTMEIscore system was constructed with principal component analysis (PCA) to determine the immune infiltration pattern of individual tumors. Results: We revealed three distinct GTMEI patterns with different clinical outcomes and modulated biological pathways. We developed a scoring system (GTMEIscore) to determine the immune infiltration pattern of individual tumors. We comprehensively analyzed the genomic characteristics, molecular subtypes and clinicopathological features as well as proteomic, phosphoproteomic, acetylomic, lipidomic and metabolomic properties associated with the GTMEIscore and revealed many novel dysregulated pathways and precise targets in GBM. Moreover, the GTMEIscore accurately quantified the immune status of many other cancer types. Clinically, the GTMEIscore was found to have significant potential therapeutic value for chemotherapy/radiotherapy, immune checkpoint inhibitor (ICI) therapy and targeted therapy. Conclusions: For the first time, we employed a multilevel and multiplatform strategy to construct a multidimensional molecular map of tumors with different immune infiltration patterns. These results may provide theoretical basises for identifying more effective predictive biomarkers and developing more effective drug combination strategies or novel immunotherapeutic agents for GBM.

The N6-methyladenosine-mediated lncRNA WEE2-AS1 promotes glioblastoma progression by stabilizing RPN2.

Background: Glioblastoma (GBM) is the most common primary brain malignancy and has high aggressiveness and a poor prognosis. N6-methyladenosine (m6A) represents the most prevalent methylation modification of lncRNAs and has been shown to play important roles in the pathophysiological processes of tumors. However, the distribution and function of m6A modifications in lncRNAs in GBM tissues have not been fully revealed. Methods: The global depiction of m6A-modified lncRNA expression patterns in GBM tumor tissues was screened via m6A high-throughput sequencing. Gain- and loss-of-function assays were performed to investigate the role of WEE2-AS1 in GBM. Mass spectrometry and RNA-pulldown, RNA immunoprecipitation (RIP), luciferase reporter and coimmunoprecipitation assays were performed to explore the mechanism of m6A-mediated upregulation of WEE2-AS1 expression and the downstream mechanism promoting the malignant progression of GBM. Results: Herein, we report the differential expression profile of m6A-modified lncRNAs in human GBM tissues for the first time. WEE2-AS1 was identified as a novel m6A-modified lncRNA that promotes GBM progression and was post-transcriptionally stabilized by IGF2BP3, an m6A reader. Moreover, we confirmed that WEE2-AS1 promoted RPN2 protein stabilization by preventing CUL2-mediated RPN2 K322 ubiquitination, thereby contributing to GBM malignant progression by activating the PI3K-Akt signaling pathway. In translational medicine, we found that blocking WEE2-AS1 expression improved the therapeutic sensitivity of dasatinib, a central nervous system penetrant that is FDA-approved in GBM. Conclusions: Overall, this work highlights that WEE2-AS1 may serve as a potential prognostic biomarker and therapeutic target in GBM, the knockdown of which significantly improves the efficacy of dasatinib, providing a promising strategy for improving targeted combination therapy for GBM patients.

The dual role of glioma exosomal microRNAs: glioma eliminates tumor suppressor miR-1298-5p via exosomes to promote immunosuppressive effects of MDSCs.

Clear evidence shows that tumors could secrete microRNAs (miRNAs) via exosomes to modulate the tumor microenvironment (TME). However, the mechanisms sorting specific miRNAs into exosomes are still unclear. In order to study the biological function and characterization of exosomal miRNAs, we performed whole-transcriptome sequencing in 59 patients' whole-course cerebrospinal fluid (CSF) small extracellular vesicles (sEV) and matched glioma tissue samples. The results demonstrate that miRNAs could be divided into exosome-enriched miRNAs (ExomiRNAs) and intracellular-retained miRNAs (CLmiRNAs), and exosome-enriched miRNAs generally play a dual role. Among them, miR-1298-5p was enriched in CSF exosomes and suppressed glioma progression in vitro and vivo experiments. Interestingly, exosomal miR-1298-5p could promote the immunosuppressive effects of myeloid-derived suppressor cells (MDSCs) to facilitate glioma. Therefore, we found miR-1298-5p had different effects on glioma cells and MDSCs. Mechanically, downstream signaling pathway analyses showed that miR-1298-5p plays distinct roles in glioma cells and MDSCs via targeting SETD7 and MSH2, respectively. Moreover, reverse verification was performed on the intracellular-retained miRNA miR-9-5p. Thus, we confirmed that tumor-suppressive miRNAs in glioma cells could be eliminated through exosomes and target tumor-associated immune cells to induce tumor-promoting phenotypes. Glioma could get double benefit from it. These findings uncover the mechanisms that glioma selectively sorts miRNAs into exosomes and modulates tumor immunity.

SPI1-induced downregulation of FTO promotes GBM progression by regulating pri-miR-10a processing in an m6A-dependent manner.

As one of the most common post-transcriptional modifications of mRNAs and noncoding RNAs, N6-methyladenosine (m6A) modification regulates almost every aspect of RNA metabolism. Evidence indicates that dysregulation of m6A modification and associated proteins contributes to glioblastoma (GBM) progression. However, the function of fat mass and obesity-associated protein (FTO), an m6A demethylase, has not been systematically and comprehensively explored in GBM. Here, we found that decreased FTO expression in clinical specimens correlated with higher glioma grades and poorer clinical outcomes. Functionally, FTO inhibited growth and invasion in GBM cells in vitro and in vivo. Mechanistically, FTO regulated the m6A modification of primary microRNA-10a (pri-miR-10a), which could be recognized by reader HNRNPA2B1, recruiting the microRNA microprocessor complex protein DGCR8 and mediating pri-miR-10a processing. Furthermore, the transcriptional activity of FTO was inhibited by the transcription factor SPI1, which could be specifically disrupted by the SPI1 inhibitor DB2313. Treatment with this inhibitor restored endogenous FTO expression and decreased GBM tumor burden, suggesting that FTO may serve as a novel prognostic indicator and therapeutic molecular target of GBM.

MicroRNA-29a-3p delivery via exosomes derived from engineered human mesenchymal stem cells exerts tumour suppressive effects by inhibiting migration and vasculogenic mimicry in glioma.

Vasculogenic mimicry (VM), the formation of an alternative microvascular circulation independent of VEGF-driven angiogenesis, is reluctant to anti-angiogenesis therapy for glioma patients. However, treatments targeting VM are lacking due to the poor understanding of the molecular mechanism involved in VM formation. By analysing the TCGA database, microRNA-29a-3p (miR-29a-3p) was found to be highly expressed in normal brain tissue compared with glioma. An in vitro study revealed an inhibitory role for miR-29a-3p in glioma cell migration and VM formation, and further study confirmed that ROBO1 is a direct target of miR-29a-3p. Based on this, we engineered human mesenchymal stem cells (MSCs) to produce miR-29a-3p-overexpressing exosomes. Treatment with these exosomes attenuated migration and VM formation in glioma cells. Moreover, the anti-glioma role of miR-29a-3p and miR-29a-3p-overexpressing exosomes were confirmed in vivo. Overall, the present study demonstrates that MSCs can be used to produce miR-29a-3p-overexpressing exosomes, which have great potential for anti-VM therapy and may act as supplements to anti-angiogenetic therapy in the clinic.

The N6-Methyladenosine-Modified Pseudogene HSPA7 Correlates With the Tumor Microenvironment and Predicts the Response to Immune Checkpoint Therapy in Glioblastoma.

Background: Glioblastoma (GBM), one of the most aggressive tumors of the brain, has no effective or sufficient therapies. Identifying robust biomarkers for the response to immune checkpoint blockade (ICB) therapy, a promising treatment option for GBM patients, is urgently needed. Methods: We comprehensively evaluated lncRNA m6A modification patterns in m6A-sequencing (m6A-seq) data for GBM tissues and systematically investigated the immune and stromal regulators of these m6A-regulated lncRNAs. We used the single-sample gene-set enrichment analysis (ssGSEA) algorithm to investigate the difference in enriched tumor microenvironment (TME) infiltrating cells and the functional annotation of HSPA7 in individual GBM samples. Further, we validated that HSPA7 promoted the recruitment of macrophages into GBM TME in vitro, as well as in our GBM tissue section. We also explored its impact on the efficacy of ICB therapy using the patient-derived glioblastoma organoid (GBO) model. Results: Here, we depicted the first transcriptome-wide m6A methylation profile of lncRNAs in GBM, revealing highly distinct lncRNA m6A modification patterns compared to those in normal brain tissues. We identified the m6A-modified pseudogene HSPA7 as a novel prognostic risk factor in GBM patients, with crucial roles in immunophenotype determination, stromal activation, and carcinogenic pathway activation. We confirmed that HSPA7 promoted macrophage infiltration and SPP1 expression via upregulating the YAP1 and LOX expression of glioblastoma stem cells (GSCs) in vitro and in our clinical GBM tumor samples. We also confirmed that knockdown of HSPA7 might increase the efficiency of anti-PD1 therapy utilizing the GBO model, highlighting its potential as a novel target for immunotherapy. Conclusions: Our results indicated that HSPA7 could be a novel immunotherapy target for GBM patients.

Hypoxic glioma-derived exosomes promote M2-like macrophage polarization by enhancing autophagy induction.

Exosomes participate in intercellular communication and glioma microenvironment modulation, but the exact mechanisms by which glioma-derived exosomes (GDEs) promote the generation of the immunosuppressive microenvironment are still unclear. Here, we investigated the effects of GDEs on autophagy, the polarization of tumor-associated macrophages (TAMs), and glioma progression. Compared with normoxic glioma-derived exosomes (N-GDEs), hypoxic glioma-derived exosomes (H-GDEs) markedly facilitated autophagy and M2-like macrophage polarization, which subsequently promoted glioma proliferation and migration in vitro and in vivo. Western blot and qRT-PCR analyses indicated that interleukin 6 (IL-6) and miR-155-3p were highly expressed in H-GDEs. Further experiments showed that IL-6 and miR-155-3p induced M2-like macrophage polarization via the IL-6-pSTAT3-miR-155-3p-autophagy-pSTAT3 positive feedback loop, which promotes glioma progression. Our study clarifies a mechanism by which hypoxia and glioma influence autophagy and M2-like macrophage polarization via exosomes, which could advance the formation of the immunosuppressive microenvironment. Our findings suggest that IL-6 and miR-155-3p may be novel biomarkers for diagnosing glioma and that treatments targeting autophagy and the STAT3 pathway may contribute to antitumor immunotherapy.

Transfer of MicroRNA via Macrophage-Derived Extracellular Vesicles Promotes Proneural-to-Mesenchymal Transition in Glioma Stem Cells.

Proneural-to-mesenchymal transition (PMT) is a common process in glioblastoma (GBM) progression that leads to increased radiotherapy resistance. However, the mechanism underlying PMT is poorly understood. Here, we found that tumor-associated macrophages triggered PMT in glioma stem cells (GSC) via small extracellular vesicles (sEV). sEVs from monocyte-derived macrophages transferred miR-27a-3p, miR-22-3p, and miR-221-3p to GSCs, and these miRNAs promoted several mesenchymal phenotypes in proneural (PN) GSCs by simultaneously targeting CHD7 We found that CHD7 played a critical role in the maintenance of the PN phenotype, and CHD7 knockdown significantly promoted PMT in GSCs via the RelB/P50 and p-STAT3 pathways. The induction of PMT by sEVs containing miR-27a-3p, miR-22-3p, and miR-221-3p in a xenograft nude mouse model exacerbated radiotherapy resistance and thus decreased the benefits of radiotherapy. Collectively, these findings identified macrophage-derived sEVs as key regulators of PMT in GSCs and demonstrated that CHD7 is a novel inhibitor of PMT.