Glioma Cell Growth Research Articles

Abstract C080: Glioma cell-mediated hyper-thrombotic tumor microenvironment drives glioblastoma growth

Abstract Cancer-related thrombosis is the second leading cause of death for cancer patients, including those with glioblastoma (GBM), the most common primary malignant brain tumor. Patients with GBM have a 30% risk of venous thromboembolism (VTE). High platelet counts, and increased platelet reactivity are associated with poor clinical outcomes in many cancers. While platelets are known to promote progression of tumors, the mechanisms by which these changes in platelet reactivity act as a driver for GBM progression is unknown. Our previous work demonstrated that a subpopulation of glioma cells activates platelets to promote GBM cell growth by intrinsically producing thrombin via a cell intrinsic functional coagulation cascade. These findings provided evidence that glioma cells can readily execute a highly liver-specific gene expression program that contributes to a hyper-thrombotic state in the GBM tumor microenvironment (TME). We now demonstrate thrombin and platelet expression in GBM patient specimen creates a hyper-thrombotic GBM tumor-microenvironment and that GBM patient platelets have increased reactivity compared to healthy patients. Further, genetic targeting of the intrinsic coagulation cascade, via knockdown of coagulation factor 11 (F11) and coagulation factor 12 (F12), reduces glioma cell growth and tumor formation while also decreasing the ability for glioma cells to activate platelets, subsequently decreasing the hyper-thrombotic state seen in the GBM tumor microenvironment. Our observations suggest that glioma cells execute a cell intrinsic coagulation mechanism to contribute to the hyper-thrombotic tumor-microenvironment seen in GBM and may shed light onto mechanisms of cancer associated thrombosis in not only GBM, but also other malignancies. Citation Format: George Bukenya, Anthony Sloan, Craig Horbinski, Anirban Sen Gupta, Scott Cameron, Justin Lathia. Glioma cell-mediated hyper-thrombotic tumor microenvironment drives glioblastoma growth [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C080.

Regulation of a novel circATP8B4/miR-31-5p/nestin ceRNA crosstalk in proliferation, motility, invasion and radiosensitivity of human glioma cells.

Deregulation of circular RNAs (circRNAs) is frequent in human glioma. Although circRNA ATPase phospholipid transporting 8B4 (circATP8B4) is highly expressed in glioma, its precise action in glioma development is still not fully understood. The relationship of microRNA (miR)-31-5p and circATP8B4 or nestin (NES) was predicted by bioinformatic analysis and confirmed by RNA pull-down and Dual-luciferase reporter assays. CircATP8B4, miR-31-5p and NES were quantified by qRT-PCR or western blot. Cell functional behaviors were assessed by EdU, wound-healing and transwell invasion assays. Xenograft model experiments were performed to define circATP8B4's activity in vivo. CircATP8B4, a true circular transcript, was upregulated in human glioma. CircATP8B4 downregulation weakened glioma cell growth, motility, and invasion and facilitated radiosensitivity. Mechanistically, circATP8B4 and NES 3'UTR harbored a shared miR-31-5p pairing site, and circATP8B4 involved the post-transcriptional NES regulation by functioning as a competing endogenous RNA (ceRNA). Furthermore, the miR-31-5p/NES axis participated in circATP8B4's activity in glioma cell proliferation, motility, invasion and radiosensitivity. Additionally, circATP8B4 loss diminished tumor growth and enhanced the anticancer effect of radiotherapy in vivo. We have uncovered an uncharacterized ceRNA cascade, circATP8B4/miR-31-5p/NES axis, underlying glioma development and radiosensitivity. Targeting the ceRNA crosstalk may have potential to improve the outcome of glioma patients.

Defective autophagy of pericytes enhances radiation-induced senescence promoting radiation brain injury.

Radiation-induced brain injury (RBI) represents a major challenge for cancer patients undergoing cranial radiotherapy. However, the molecular mechanisms and therapeutic strategies of RBI remain inconclusive. With the continuous exploration of the mechanisms of RBI, an increasing number of studies have implicated cerebrovascular dysfunction as a key factor in RBI-related cognitive impairment. As pericytes are a component of the neurovascular unit, there is still a lack of understanding in current research about the specific role and function of pericytes in RBI. We constructed a mouse model of RBI-associated cognitive dysfunction in vivo and an in vitro radiation-induced pericyte model to explore the effects of senescent pericytes on the blood-brain barrier and normal CNS cells, even glioma cells. To further clarify the effects of pericyte autophagy on senescence, molecular mechanisms were explored at the animal and cellular levels. Finally, we validated the clearance of pericyte senescence by using senolytic drug and all-trans retinoic acid to investigate the role of radiation-induced pericyte senescence. Our findings indicated that radiation-induced pericyte senescence plays a key role in blood-brain barrier dysfunction, leading to RBI and subsequent cognitive decline. Strikingly, pericyte senescence also contributes to the growth and invasion of glioma cells. We further demonstrate that defective autophagy in pericytes is a vital regulatory mechanism for pericyte senescence. Moreover, autophagy activated by rapamycin can reverse pericyte senescence. Notably, the elimination of senescent cells by senolytic drugs significantly mitigated radiation-induced cognitive dysfunction. Our results demonstrated that pericyte senescence may be a promising therapeutic target for RBI and glioma progression.

Crocetin Enhances Temozolomide Efficacy in Glioblastoma Therapy Through Multiple Pathway Suppression.

Glioblastoma multiforme (GBM) is an aggressive type of brain tumor that is difficult to remove surgically. Research suggests that substances from saffron, namely crocetin and crocin, could be effective natural treatments, showing abilities to kill cancer cells. Our study focused on evaluating the effects of crocetin on glioma using the U87 cell line. We specifically investigated how crocetin affects the survival, growth, and spread of glioma cells, exploring its impact at concentrations ranging from 75-150 μM. The study also included experiments combining crocetin with the chemotherapy drug Temozolomide (TMZ) to assess potential synergistic effects. Crocetin significantly reduced the viability, proliferation, and migration of glioma cells. It achieved these effects by decreasing the levels of Matrix Metallopeptidase 9 (MMP-9) and Ras homolog family member A (RhoA), proteins that are critical for cancer progression. Additionally, crocetin inhibited the formation of cellular structures necessary for tumor growth. It blocked multiple points of the Ak Strain Transforming (AKT) signaling pathway, which is vital for cancer cell survival. This treatment led to increased cell death and disrupted the cell cycle in the glioma cells. When used in combination with TMZ, crocetin not only enhanced the reduction of cancer cell growth but also promoted cell death and reduced cell replication. This combination therapy further decreased levels of high mobility group box 1 (HMGB1) and Receptor for Advanced Glycation End-products (RAGE), proteins linked to inflammation and tumor progression. It selectively inhibited certain pathways involved in the cellular stress response without affecting others. Our results underscore the potential of crocetin as a treatment for glioma. It targets various mechanisms involved in tumor growth and spread, offering multiple avenues for therapy. Further studies are essential to fully understand and utilize crocetin's benefits in treating glioma.

CBX2 enhances the progression and TMZ chemoresistance of glioma via EZH2-mediated epigenetic silencing of PTEN expression.

Chromobox (CBX) 2, a member of the CBX protein family and a crucial component of the polycomb repressive complex (PRC), exerts significant influence on the epigenetic regulation of tumorigenesis, including glioma. However, the precise role of CBX2 in glioma has remained elusive. In our study, we observed a substantial upregulation of CBX2 expression in glioma, which displayed a strong correlation with pathological grade, chemoresistance, and unfavorable prognosis. Through a series of in vivo and in vitro experiments, we established that heightened CBX2 expression facilitated glioma cell proliferation and bolstered resistance to chemotherapy. Conversely, CBX2 knockdown led to a significant inhibition of glioma cell growth and a reduction in chemoresistance. Notably, our investigation uncovered the underlying mechanism by which CBX2 operates, primarily by inhibiting PTEN transcription and activating the AKT/mTOR signalling pathway. Conversely, silencing CBX2 curtailed cell proliferation and attenuated chemoresistance by impeding the activation of the PTEN/AKT/mTOR signalling pathway. Delving deeper into the molecular intricacies, we discovered that CBX2 can recruit EZH2 and modulate the trimethylation of histone H3 lysine 27 (H3K27me3) levels on the PTEN promoter, effectively suppressing PTEN transcription. Our research unveils a comprehensive understanding of how CBX2 impacts the tumorigenesis, progression, chemoresistance, and prognosis of glioma. Furthermore, it presents CBX2 as a promising therapeutic target for drug development and clinical management of glioma.

RETRACTION: MicroRNA-16 inhibits glioma cell growth and invasion through suppression of BCL2 and the nuclear factor-κB1/MMP9 signaling pathway.

Retraction: T.-Q. Yang, X.-J. Lu, T.-F. Wu, D.-D. Ding, Z.-H. Zhao, G.-L. Chen, X.-S. Xie, B. Li, Y.-X. Wei, L.-C. Guo, Y. Zhang, Y.-L. Huang, Y.-X. Zhou, and Z.-W. Du, "MicroRNA-16 inhibits glioma cell growth and invasion through suppression of BCL2 and the nuclear factor-κB1/MMP9 signaling pathway," Cancer Science 105 no. 3 (2014): 265-271. https://doi.org/10.1111/cas.12351. The above article, published online on 13 January 2014 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal Editor-in-Chief, Masanori Hatakeyama; the Japanese Cancer Association; and John Wiley and Sons Ltd. The journal had previously published a correction regarding duplicated portions of Figure4a on 24 May 2022. Following publication of this correction, the journal was made aware that not all duplicated portions of Figure4a had been replaced. Additionally, concerns were raised of splicing in Figure2d and image duplications in Figures2d, 3d, and 4c. The authors did not respond to inquiries from the publisher regarding these concerns. and did not provide the requested original images and data. Therefore, the data reported in this article are considered unreliable and the journal must issue a retraction. The authors did not respond to our notice of retraction.

A novel nanoplatform-based circCSNK1G3 affects CBX7 protein and promotes glioma cell growth

Bioenvironmental and biological factors have the potential to contribute to the development of glioma, a type of brain tumor. Recent studies have suggested that a unique circular RNA called circCSNK1G3 could play a role in promoting the growth of glioma cells. It does this by stabilizing a specific microRNA called miR-181 and reducing the expression of a tumor-suppressor gene known as chromobox protein homolog 7 (CBX7). To further investigate circCSNK1G3 and its effects on glioma, we utilized a nanoplatform called adeno-associated virus (AAV)-RNAi.To explore the functional implications of circCSNK1G3, we employed siRNA to silence its expression. Along with these effects, the silencing of circCSNK1G3 led to a depletion of miR-181d and an upregulation of CBX7. When we introduced miR-181d mimics, which artificially increase the levels of miR-181d, the anti-glioma cell activity induced by circCSNK1G3 siRNA was almost completely reversed. Conversely, inhibiting miR-181d mimicked the effects of circCSNK1G3 silencing. Moreover, when we overexpressed circCSNK1G3 in glioma cells, we observed an elevation of miR-181d and a depletion of CBX7. We found that the growth of A172 xenografts (tumors) carrying circCSNK1G3 shRNA was significantly inhibited. In these xenograft tissues, we detected a depletion of circCSNK1G3 and miR-181d, as well as an upregulation of CBX7.

Origin recognition complex 6 overexpression promotes growth of glioma cells

The discovery of novel oncotargets for glioma is of immense significance. We here explored the expression patterns, biological functions, and underlying mechanisms associated with ORC6 (origin recognition complex 6) in glioma. Through the bioinformatics analyses, we found a significant increase in ORC6 expression within human glioma tissues, correlating with poorer overall survival, higher tumor grade, and wild-type isocitrate dehydrogenase status. Additionally, ORC6 overexpression is detected in glioma tissues obtained from locally-treated patients and across various primary/established glioma cells. Further bioinformatics scrutiny revealed that genes co-expressed with ORC6 are enriched in multiple signaling cascades linked to cancer. In primary and immortalized (A172) glioma cells, depleting ORC6 using specific shRNA or Cas9-sgRNA knockout (KO) significantly decreased cell viability and proliferation, disrupted cell cycle progression and mobility, and triggered apoptosis. Conversely, enhancing ORC6 expression via a lentiviral construct augmented malignant behaviors in human glioma cells. ORC6 emerged as a crucial regulator for the expression of key oncogenic genes, including Cyclin A2, Cyclin B2, and DNA topoisomerase II (TOP2A), within glioma cells. Silencing or KO of ORC6 reduced the mRNA and protein levels of these genes, while overexpression of ORC6 increased their expression in primary glioma cells. Bioinformatics analyses further identified RBPJ as a potential transcription factor of ORC6. RBPJ shRNA decreased ORC6 expression in primary glioma cells, while its overexpression increased it. Additionally, significantly enhanced binding between the RBPJ protein and the proposed ORC6 promoter region was detected in glioma tissues and cells. In vivo experiments demonstrated a significant reduction in the growth of patient-derived glioma xenografts in the mouse brain subsequent to ORC6 KO. ORC6 depletion, inhibited proliferation, decreased expression of Cyclin A2/B2/TOP2A, and increased apoptosis were detected within these ORC6 KO intracranial glioma xenografts. Altogether, RBPJ-driven ORC6 overexpression promotes glioma cell growth, underscoring its significance as a promising therapeutic target.

Fatty Acid Amides Suppress Proliferation via Cannabinoid Receptors and Promote the Apoptosis of C6 Glioma Cells in Association with Akt Signaling Pathway Inhibition.

A glioma is a type of tumor that acts on the Central Nervous System (CNS) in a highly aggressive manner. Gliomas can occasionally be inaccurately diagnosed and treatments have low efficacy, meaning that patients exhibit a survival of less than one year after diagnosis. Due to factors such as intratumoral cell variability, inefficient chemotherapy drugs, adaptive resistance development to drugs and tumor recurrence after resection, the search continues for new drugs that can inhibit glioma cell growth. As such, analogues of endocannabinoids, such as fatty acid amides (FAAs), represent interesting alternatives for inhibiting tumor growth, since FAAs can modulate several metabolic pathways linked to cancer and, thus, may hold potential for managing glioblastoma. The aim of this study was to investigate the in vitro effects of two fatty ethanolamides (FAA1 and FAA2), synthetized via direct amidation from andiroba oil (Carapa guianensis Aublet), on C6 glioma cells. FAA1 and FAA2 reduced C6 cell viability, proliferation and migratory potential in a dose-dependent manner and were not toxic to normal retina glial cells. Both FAAs caused apoptotic cell death through the loss of mitochondrial integrity (ΔΨm), probably by activating cannabinoid receptors, and inhibiting the PI3K/Akt pathway. In conclusion, FAAs derived from natural products may have the potential to treat glioma-type brain cancer.

Silencing UBE2K inhibits the growth of glioma cells by inducing the autophagy-related apoptosis.

Glioma is a central nervous system (CNS) malignant tumor with high heterogeneity and mortality, which severely threatens the health of patients. The overall survival of glioma patients is relatively short and it is critical to identify new molecular targets for developing effective treatment strategies. UBE2K is a ubiquitin conjugating enzyme with oncogenic function in several malignant tumors. However, whether UBE2K participates in gliomas remains unknown. Herein, in glioma cells, UBE2K was found highly expressed in U87 and U251 cells. Subsequently, U87 and U251 cells were transfected with si-UBE2K to silence UBE2K, with the si-NC transfection as the negative control. In both U87 and U251 cells, the cell viability was sharply reduced by transfecting si-UBE2K for 48 and 72 h. Markedly decreased colony number, reduced number of migrated cells and invaded cells, and declined relative wound healing rate were observed in si-UBE2K transfected U87 and U251 cells. Moreover, the Bcl-2 level was markedly reduced, while the Bax and cleaved-caspase-3 levels were sharply increased in U87 and U251 cells after the si-UBE2K transfection. Furthermore, the p62 level was signally declined, while the Beclin-1 and LC-3 II/I levels were greatly increased in U87 and U251 cells by the si-UBE2K transfection. Furthermore, the facilitating effect of si-UBE2K on the apoptosis and autophagy in U87 and U251 cells was abolished by the coculture of 3-MA, an inhibitor of autophagy. Collectively, UBE2K facilitated the in vitro growth of glioma cells, possibly by inhibiting the autophagy-related apoptosis, which might be a promising target for treating glioma.

EIF4A3-Induced Circ_0059914 Promoted Angiogenesis and EMT of Glioma via the miR-1249/VEGFA Pathway.

Gliomas are common brain tumors. Despite extensive research, the 5-year survival rate of glioma remains low. Many studies have reported that circular RNAs (circRNAs) play a role in promoting the malignant progression of glioma; however, the role of circ_0059914 in this process remains unclear. In this study, we aimed to investigate the function and underlying mechanism of circ_0059914 in glioma. Western blotting and qRT-PCR were used to determine the levels of circ_0059914, miR-1249, VEGFA, N-cadherin, vimentin, Snail, and EIF4A3. EDU and colony formation assays were conducted to evaluate cell proliferation. Transwell assays were used to explore cell migration and invasion and tube formation assays were used to analyze angiogenesis. RNA immunoprecipitation (RIP) and dual-luciferase reporter assays were used to explore the relationship between EIF4A3, circ_0059914, miR-1249, and VEGFA. A xenograft tumor assay was performed to determine the role of circ_0059914 in vivo. Circ_0059914 expression was upregulated in gliomas. Knockdown of gliomal circ_0059914 expression reduced the proliferation, migration, invasion, epithelial-mesenchymal transition (EMT), angiogenesis, and growth of glioma cells in vivo. Circ_0059914 sponged miR-1249, and miR-1249 inhibition reversed the circ_0059914 knockdown-mediated effects in glioma cells. VEGFA was found to be a target gene of miR1249; overexpression of VEGFA reversed the effect of miR-1249 up-regulation in glioma. Finally, EIF4A3 increased the expression of circ_0059914. EIF4A3-induced circ_0059914 expression plays a role in promoting glioma via the miR-1249/VEGFA axis.

NFS-10. ROLE OF CDKN2A CO-DELETION IN DRIVING TUMOR INVASIVENESS IN NF1 MUTANT GLIOMA

Abstract BACKGROUND Neurofibromatosis type 1, caused by mutations in the NF1 gene, is a common autosomal dominant genetic disorder associated with an increased risk of glioma tumor development. A high occurrence of CDKN2a codeletion in NF1-mutant high-grade gliomas (HGG) compared to low-grade gliomas (LGG) implies a potential role of CDKN2a loss in the transformation of NF1-mutant LGG to HGG. In our study, we aimed to elucidate the role of NF1 and CDKN2a in tumor transformation using a panel of glioma cell line models with varying NF1 and CDKN2a expression. METHOD A diverse panel of glioma cell lines, encompassing LGG (1667-ON, RES259, RES186, JHH-NF1-PA1) and HGG (GBM511, GBM110, SF8628, U87-MG, TM-31, 7316-2189, 7316-3058, 7316-4917), was cultured. Their growth rates and invasiveness were further evaluated using cell proliferation and Boyden chamber invasiveness assays. RESULTS LGG cell lines exhibited relatively lower growth rates and invasiveness compared to their high-grade counterparts. Intriguingly, RES259, a LGG cell line harboring both NF1 and CDKN2a variants, demonstrated the highest growth rate and invasiveness among LGG cell lines, surpassing even those with intact NF1 and CDKN2a, such as JHH-NF1-PA1 and RES186. To further elucidate the roles of NF1 and CDKN2a, CRISPR-Cas9 technology was employed to knockout these genes individually and in various combinations in RES186. Our findings unveiled that sole NF1 knockout had negligible impact on RES186. Conversely, CDKN2a knockout increased both growth rate and invasiveness. Strikingly, the codeletion of NF1 and CDKN2a in RES186 significantly exacerbated its growth rate and invasiveness. These results underscore the intricate interplay of NF1 and CDKN2a in governing the growth and invasiveness dynamics of glioma cells. CONCLUSION In conclusion, our preliminary study suggests that the concurrent loss of NF1 and CDKN2a promotes enhanced growth and invasiveness in gliomas, shedding light on the collaborative role of these genetic alterations in tumor transformation.

Metabolic dysregulation of tricarboxylic acid cycle and oxidative phosphorylation in glioblastoma.

Glioblastoma multiforme (GBM) exhibits genetic alterations that induce the deregulation of oncogenic pathways, thus promoting metabolic adaptation. The modulation of metabolic enzyme activities is necessary to generate nucleotides, amino acids, and fatty acids, which provide energy and metabolic intermediates essential for fulfilling the biosynthetic needs of glioma cells. Moreover, the TCA cycle produces intermediates that play important roles in the metabolism of glucose, fatty acids, or non-essential amino acids, and act as signaling molecules associated withthe activation of oncogenic pathways, transcriptional changes, and epigenetic modifications. In this review, we aim to explore how dysregulated metabolic enzymes from the TCA cycle and oxidative phosphorylation, along with their metabolites, modulate both catabolic and anabolic metabolic pathways, as well as pro-oncogenic signaling pathways, transcriptional changes, and epigenetic modifications in GBM cells, contributing to the formation, survival, growth, and invasion of glioma cells. Additionally, we discuss promising therapeutic strategies targeting key players in metabolic regulation. Therefore, understanding metabolic reprogramming is necessary to fully comprehend the biology of malignant gliomas and significantly improve patient survival.

Remotely Controlled 3D-Engineered Scaffolds for Biomimetic In Vitro Investigations on Brain Cell Cocultures.

Most in vitro studies regarding new anticancer treatments are performed on 2D cultures, despite this approach imposes several limitations in recapitulating the real tumor behavior and in predicting the effects of therapy on both cancer and healthy tissues. Herein, advanced in vitro models based on scaffolds that support the 3D growth of glioma cells, further allowing the cocultures with healthy brain cells, are presented. These scaffolds, doped with superparamagnetic iron oxide nanoparticles and obtained through 2-photon polymerization, can be remotely manipulated thanks to an external magnet, thus obtaining biomimetic 3D organization recapitulating the brain cancer microenvironment. From a geometric point of view, the structure is functional to both cell culture on individual unit scaffolds and to tailored cocultures fostered by magnetic-driven unit assembly, also allowing for cell migration thanks to passages/fenestrations on adjacent structures. Leveraging magnetic dragging, for which a mathematical model is introduced, multiple cocultures are achieved, highlighting the high versatility and the user-friendly character of the proposed platform that can help overcome the current challenges in 3D cocultures handling, and open the way to the construction of increasingly biomimetic artificial systems.

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

BackgroundIn 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.MethodsLentivirus 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.ResultsTrem2 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-1β, and caused further DNA damage and promoted the apoptosis rate of tumor cells.ConclusionsOur 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.

Oncogenic role of RNA-binding protein GNL2 in glioma: Promotion of tumor development through enhancing protein synthesis.

RNA-binding proteins (RBPs) are aberrantly expressed in various diseases, including glioma. In the present study, the role and mechanism of RBPs in glioma were investigated. Differentially expressed genes (DEGs) in glioma were screened from public databases and overlapping genes between DEGs and RBPs were selected in a bioinformatics analysis to identify the hub gene. Next, evaluation of expression, survival analysis and cell experiments were performed to examine the impact of the hub gene on glioma. Through bioinformatics analysis, G protein nucleolar 2 (GNL2), programmed cell death 11 (PDCD11) and ribosomal protein S6 (RPS6) were identified as potential biomarkers in glioma prognosis and GNL2 was chosen as the hub gene for further investigation. GNL2 was increased in glioma tissues and related to poor survival outcomes. Cell experiments revealed that GNL2 knockdown inhibited glioma cell growth, migration and invasion. In addition, GNL2 was found to affect the overall protein synthesis of ribosomal protein L11 in glioma cells. In conclusion, GNL2, PDCD11 and RPS6 may serve as potential biomarkers in glioma prognosis. Importantly, GNL2 acts as an oncogene in glioma and it enhances protein synthesis to promote the development of brain glioma.

Rebound growth of BRAF mutant pediatric glioma cells after MAPKi withdrawal is associated with MAPK reactivation and secretion of microglia-recruiting cytokines

IntroductionPatients with pediatric low-grade gliomas (pLGGs), the most common primary brain tumors in children, can often benefit from MAPK inhibitor (MAPKi) treatment. However, rapid tumor regrowth, also referred to as rebound growth, may occur once treatment is stopped, constituting a significant clinical challenge.MethodsFour patient-derived pediatric glioma models were investigated to model rebound growth in vitro based on viable cell counts in response to MAPKi treatment and withdrawal. A multi-omics dataset (RNA sequencing and LC-MS/MS based phospho-/proteomics) was generated to investigate possible rebound-driving mechanisms. Following in vitro validation, putative rebound-driving mechanisms were validated in vivo using the BT-40 orthotopic xenograft model.ResultsOf the tested models, only a BRAFV600E-driven model (BT-40, with additional CDKN2A/Bdel) showed rebound growth upon MAPKi withdrawal. Using this model, we identified a rapid reactivation of the MAPK pathway upon MAPKi withdrawal in vitro, also confirmed in vivo. Furthermore, transient overactivation of key MAPK molecules at transcriptional (e.g. FOS) and phosphorylation (e.g. pMEK) levels, was observed in vitro. Additionally, we detected increased expression and secretion of cytokines (CCL2, CX3CL1, CXCL10 and CCL7) upon MAPKi treatment, maintained during early withdrawal. While increased cytokine expression did not have tumor cell intrinsic effects, presence of these cytokines in conditioned media led to increased attraction of microglia cells in vitro.ConclusionTaken together, these data indicate rapid MAPK reactivation upon MAPKi withdrawal as a tumor cell intrinsic rebound-driving mechanism. Furthermore, increased secretion of microglia-recruiting cytokines may play a role in treatment response and rebound growth upon withdrawal, warranting further evaluation.

GPR27 expression correlates with prognosis and tumor progression in gliomas.

Glioma is a highly aggressive type of brain tumor, and its prognosis is still poor despite recent progress in treatment strategies. G protein-coupled receptor 27 (GPR27) is a member of the G protein-coupled receptor family and has been reported to be involved in various cellular processes, including tumor progression. Nevertheless, the clinical potential and tumor-related role of GPR27 in glioma remain unknown. Here we aimed to explore the function and role of GPR27 in gliomas. In the current study, we evaluated the expression and clinical significance of GPR27 in gliomas using data from The Cancer Genome Atlas (TCGA) datasets. We also conducted cellular experiments to evaluate the functional role of GPR27 in glioma cell growth. We found that GPR27 expression level was closely associated with disease status of glioma. Of note, GPR27 was negatively correlated with WHO grade, with grade IV samples showing the lowest GPR27 levels, while grade II samples showed the highest levels. Patients with IDH mutation or 1p/19q co-deletion exhibited higher GPR27 levels. In addition, lower GPR27 levels were correlated with higher death possibilities. In cellular experiments, we confirmed that GPR27 inhibited glioma cell growth. Our results indicate that GPR27 may function as a potential prognostic biomarker and therapeutic target in gliomas. Further studies are needed to illustrate the signaling mechanism and clinical implications of GPR27 in gliomas.

PD-1/PD-L1 axis is involved in the interaction between microglial polarization and glioma

The tumor microenvironment plays a vital role in glioblastoma growth and invasion. PD-1 and PD-L1 modulate the immunity in the brain tumor microenvironment. However, the underlying mechanisms remain unclear. In the present study, in vivo and in vitro experiments were conducted to reveal the effects of PD-1/PD-L1 on the crosstalk between microglia and glioma. Results showed that glioma cells secreted PD-L1 to the peritumoral areas, particularly microglia containing highly expressed PD-1. In the early stages of glioma, microglia mainly polarized into the pro-inflammatory subtype (M1). Subsequently, the secreted PD-L1 accumulated and bound to PD-1 on microglia, facilitating their polarization toward the microglial anti-inflammatory (M2) subtype primarily via the STAT3 signaling pathway. The role of PD-1/PD-L1 in M2 polarization of microglia was partially due to PD-1/PD-L1 depletion or application of BMS-1166, a novel inhibitor of PD-1/PD-L1. Consistently, co-culturing with microglia promoted glioma cell growth and invasion, and blocking PD-1/PD-L1 significantly suppressed these processes. Our findings reveal that the PD-1/PD-L1 axis engages in the microglial M2 polarization in the glioma microenvironment and promotes tumor growth and invasion.

Has-miR-134-5p inhibits the proliferation and migration of glioma cells by regulating the BDNF/ERK signaling pathway.

Our research investigated the effects of hsa-miR-134-5p on glioma progression, focusing on its interaction with the BDNF/ERK signaling pathway. U251 and U87 cell lines were analyzed post-transfection with hsa-miR-134-5p mimics and inhibitors, confirming the miRNA's binding to BDNF using dual luciferase assays. Q-PCR was employed to measure expression changes, revealing that hsa-miR-134-5p markedly inhibited glioma cell proliferation, migration, and invasion, as evidenced by CCK8, monoclonal formation, and Transwell assays. Scratch tests and Western blotting demonstrated hsa-miR-134-5p's modulation of the BDNF/ERK pathway and associated decrease in MMP2/9 protein levels. Flow cytometry suggested that hsa-miR-134-5p might also block the G0/S phase transition. In vivo studies using nude mice corroborated the tumor-suppressing effects of hsa-miR-134-5p, which were negated by elevated BDNF levels. Comparative protein analysis across groups confirmed the pathway's significance in tumorigenesis. Our findings identify hsa-miR-134-5p as a key molecule impeding glioma cell growth by curtailing the BDNF/ERK pathway, with the reversal by BDNF upregulation pointing to the potential of therapeutically exploiting the hsa-miR-134-5p/BDNF axis in glioma care.