Knockdown of trem2 promotes proinflammatory microglia and inhibits glioma progression via the JAK2/STAT3 and NF-κB pathways.

BACKGROUND: In the tumor immune microenvironment (TIME), triggering receptor expressed on myeloid cells 2 (trem2) is widely considered to be a crucial molecule on tumor-associated macrophages(TAMs). Multiple studies have shown that trem2 may function as an immune checkpoint in various malignant tumors, mediating tumor immune evasion. However, its specific molecular mechanisms, especially in glioma, remain elusive. METHODS: Lentivirus was transfected to establish cells with stable knockdown of trem2. A Transwell system was used for segregated coculture of glioma cells and microglia. Western blotting, quantitative real-time polymerase chain reaction (qRT‒PCR), and immunofluorescence (IF) were used to measure the expression levels of target proteins. The proliferation, invasion, and migration of cells were detected by colony formation, cell counting kit-8 (CCK8), 5-ethynyl-2'-deoxyuridine (EdU) and transwell assays. The cell cycle, apoptosis rate and reactive oxygen species (ROS) level of cells were assessed using flow cytometry assays. The comet assay and tube formation assay were used to detect DNA damage in glioma cells and angiogenesis activity, respectively. Gl261 cell lines and C57BL/6 mice were used to construct the glioma orthotopic transplantation tumor model. RESULTS: Trem2 was highly overexpressed in glioma TAMs. Knocking down trem2 in microglia suppressed the growth and angiogenesis activity of glioma cells in vivo and in vitro. Mechanistically, knockdown of trem2 in microglia promoted proinflammatory microglia and inhibited anti-inflammatory microglia by activating jak2/stat1 and inhibiting the NF-κB p50 signaling pathway. The proinflammatory microglia produced high concentrations of nitric oxide (NO) and high levels of the proinflammatory cytokines TNF-α, IL-6, and IL-1ß, and caused further DNA damage and promoted the apoptosis rate of tumor cells. CONCLUSIONS: Our findings revealed that trem2 in microglia plays a significant role in the TIME of gliomas. Knockdown of trem2 in microglia might help to improve the efficiency of inhibiting glioma growth and delaying tumor progression and provide new ideas for further treatment of glioma.

The mechanism of extracellular CypB promotes glioblastoma adaptation to glutamine deprivation microenvironment.

Glioblastoma, previously known as glioblastoma multiform (GBM), is a type of glioma with a high degree of malignancy and rapid growth rate. It is highly dependent on glutamine (Gln) metabolism during proliferation and lags in neoangiogenesis, leading to extensive Gln depletion in the core region of GBM. Gln-derived glutamate is used to synthesize the antioxidant Glutathione (GSH). We demonstrated that GSH levels are also reduced in Gln deficiency, leading to increased reactive oxygen species (ROS) levels. The ROS production induces endoplasmic reticulum (ER) stress, and the proteins in the ER are secreted into the extracellular medium. We collected GBM cell supernatants cultured with or without Gln medium; the core and peripheral regions of human GBM tumor tissues. Proteomic analysis was used to screen out the target-secreted protein CypB. We demonstrated that the extracellular CypB expression is associated with Gln deprivation. Then, we verified that GBM can promote the glycolytic pathway by activating HIF-1α to upregulate the expression of GLUT1 and LDHA. Meanwhile, the DRP1 was activated, increasing mitochondrial fission, thus inhibiting mitochondrial function. To explore the specific mechanism of its regulation, we constructed a si-CD147 knockout model and added human recombinant CypB protein to verify that extracellular CypB influenced the expression of downstream p-AKT through its cell membrane receptor CD147 binding. Moreover, we confirmed that p-AKT could upregulate HIF-1α and DRP1. Finally, we observed that extracellular CypB can bind to the CD147 receptor, activate p-AKT, upregulate HIF-1α and DRP1 in order to promote glycolysis while inhibiting mitochondrial function to adapt to the Gln-deprived microenvironment.

Bisphenol A: Unveiling Its Role in Glioma Progression and Tumor Growth.

Gliomas represent the most common and lethal category of primary brain tumors. Bisphenol A (BPA), a widely recognized endocrine disruptor, has been implicated in the progression of cancer. Despite its established links to various cancers, the association between BPA and glioma progression remains to be clearly defined. This study aimed to shed light on the impact of BPA on glioma cell proliferation and overall tumor progression. Our results demonstrate that BPA significantly accelerates glioma cell proliferation in a time- and dose-dependent manner. Furthermore, BPA has been found to enhance the invasive and migratory capabilities of glioma cells, potentially promoting epithelial-mesenchymal transition (EMT) characteristics within these tumors. Employing bioinformatics approaches, we devised a risk assessment model to gauge the potential glioma hazards associated with BPA exposure. Our comprehensive analysis revealed that BPA not only facilitates glioma invasion and migration but also inhibits apoptotic processes. In summary, our study offers valuable insights into the mechanisms by which BPA may promote tumorigenesis in gliomas, contributing to the understanding of its broader implications in oncology.

EEF1E1 promotes glioma proliferation by regulating cell cycle through PTEN/AKT signaling pathway.

The cell cycle, a pivotal regulator of cell proliferation, can be significantly influenced by the phosphatase and tensin homolog (PTEN)/AKT signaling pathway's modulation of cyclin-related proteins. In our study, we discovered the crucial role of EEF1E1 in this process, as it appears to downregulate PTEN expression. Furthermore, our findings affirmed that EEF1E1 modulates downstream cell cycle-related proteins by suppressing the PTEN/AKT pathway. Cell cycle assay results revealed that EEF1E1 downregulation stunted the advancement of glioma cells in both the G1 and S phases. A suite of assays-Cell Counting Kit-8, colony formation, and ethyl-2'-deoxyuridine-substantiated that the EEF1E1 downregulation markedly curtailed glioma proliferation. We further validated this phenomenon through animal studies and coculture experiments on brain slices. Our comprehensive investigation indicates that EEF1E1 knockdown can effectively inhibit the glioma cell proliferation by regulating the cell cycle via the PTEN/AKT signaling pathway. Consequently, EEF1E1 emerges as a potential therapeutic target for glioma treatment, signifying critical clinical implications.

CircRNA-104718 promotes glioma malignancy through regulation of miR-218-5p/HMGB1 signalling pathway.

Increasing number of studies have proven that circular RNAs (circRNAs) play a major role in the biological processes of many different cancers, including glioma, especially as competitive molecular sponges of microRNAs (miRNAs). However, the clear molecular mechanism of the circRNA network in glioma is still not well understood. The expression level of circRNA-104718 and microRNA (miR)-218-5p in glioma tissues and cells were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The target protein's expression level was assessed by western blotting. Bioinformatics systems were used to predict the possible microRNAs and target genes of circRNA-104718, after which dual-luciferase reporter assays were used to confirm the predicted interactions. The proliferation, invasion, migration and apoptosis of glioma cells were detected by CCK, EdU, transwell, wound-healing and flow cytometry assays. CircRNA-104718 was upregulated in human glioma tissues, and a higher level of circRNA-104718 indicated poorer outcomes in glioma patients. In contrast, in glioma tissues, miR-218-5p was downregulated. Knockdown of circRNA-104718 suppressed migration and invasion while boosting the apoptosis rate of glioma cells. In addition, the upregulation of miR-218-5p in glioma cells caused the same suppression. Mechanistically, circRNA-104718 inhibited the protein expression level of high mobility group box-1 (HMGB1) by acting as a molecular sponge for miR-218-5p. CircRNA-104718 is a suppressive factor in glioma cells and might represent a new target for the treatment of glioma patients. CircRNA-104718 modulates glioma cell proliferation through the miR-218-5p/HMGB1 signalling axis. CircRNA-104718 provides a possible mechanism for understanding the pathogenesis of glioma.

CircTCF25 serves as a sponge for miR-206 to support proliferation, migration, and invasion of glioma via the Jak2/p-Stat3/CypB axis.

Glioma is the most common primary malignant intracranial tumor in humans, and glioblastoma (GBM) has been associated with a more aggressive histology and poorer prognosis. There is growing evidence that circular RNAs (circRNAs) are involved in the progression of various malignancies; however, the role and molecular mechanism of circRNAs in glioma remain elusive. In the present study, we screened for differentially expressed circRNAs in gliomas by using a bioinformatics method. Significant upregulation in glioma tissues was verified by quantitative real-time polymerase chain reaction (qRT-PCR), and the prognostic value was evaluated. The potential oncogenic role of circular RNA TCF25 (circTCF25) in glioma was assessed both in vivo and in vitro. Bioinformatics analysis and luciferase reporter assays confirmed the interaction among circTCF25, microRNA-206 (miR-206), and its target gene Cyclophilin B (CypB). circTCF25 was predominantly located in the cytoplasm; the combination of mir-206 and circTCF25 reverses the effects of knockdown of circTCF25 on the proliferation, migration, invasion, and tumorigenesis of glioma cells. Competitive binding between circTCF25 and miR-206 mainly upregulates target gene CypB expression by preventing its inhibition of the Jak2/p-stat3 pathway. In addition, knockdown of circTCF25 reduced CypB expression by inhibiting JAK2/p-stat3, which was rescued by treatment with a miR-206 inhibitor. In summary, our findings demonstrate that the circTCF25/miR-206/CypB axis plays a vital role in glioma progression, migration, invasion, and tumorigenesis.

Expressions and significances of CTSL, the target of COVID-19 on GBM.

INTRODUCTION: Cathepsin L (CTSL) is a kind of the SARS-entry-associated CoV-2's proteases, which plays a key role in the virus's entry into the cell and subsequent infection. We investigated the association between the expression level of CTSL and overall survival in Glioblastoma multiforme (GBM) patients, to better understand the possible route and risks of new coronavirus infection for patients with GBM. METHODS: The expression level of CTSL in GBM was analyzed using TCGA and CGGA databases. The relationship between CTSL and immune infiltration levels was analyzed by means of the TIMER database. The impact of CTSL inhibitors on GBM biological activity was tested. RESULTS: The findings revealed that GBM tissues had higher CTSL expression levels than that of normal brain tissues, which was associated with a significantly lower survival rate in GBM patients. Meanwhile, the expression level of CTSL negatively correlated with purity, B cell and CD8+ T cell in GBM. CTSL inhibitor significantly reduced growth and induced mitochondrial apoptosis. CONCLUSION: According to the findings, CTSL acts as an independent prognostic factor and can be considered as promising therapeutic target for GBM.