Glutamine Metabolism Heterogeneity in Glioblastoma Unveils an Innovative Combination Therapy Strategy.

Treatment of glioblastoma multiforme (GBM) remains challenging. Unraveling the orchestration of glutamine metabolism may provide a novel viewpoint on GBM therapy. The study presented a full and comprehensive comprehending of the glutamine metabolism atlas and heterogeneity in GBM for facilitating the development of a more effective therapeutic choice. Transcriptome data from large GBM cohorts were integrated in this study. A glutamine metabolism-based classification was established through consensus clustering approach, and a classifier by LASSO analysis was defined for differentiating the classification. Prognosis, signaling pathway activity, tumor microenvironment, and responses to immune checkpoint blockade (ICB) and small molecular drugs were characterized in each cluster. A combinational therapy of glutaminase inhibitor CB839 with dihydroartemisinin (DHA) was proposed, and the influence on glutamine metabolism, apoptosis, reactive oxygen species (ROS), and migration was measured in U251 and U373 cells. We discovered that GBM presented heterogeneous glutamine metabolism-based clusters, with unique survival outcomes, activity of signaling pathways, tumor microenvironment, and responses to ICB and small molecular compounds. In addition, the classifier could accurately differentiate the two clusters. Strikingly, the combinational therapy of CB839 with DHA synergistically attenuated glutamine metabolism, triggered apoptosis and ROS accumulation, and impaired migrative capacity in GBM cells, demonstrating the excellent preclinical efficacy. Altogether, our findings unveil the glutamine metabolism heterogeneity in GBM and propose an innovative combination therapy of CB839 with DHA for this malignant disease.

Altering biomolecular condensates as a potential mechanism that mediates cannabidiol effect on glioblastoma.

Glioblastoma (GBM) is an extremely aggressive primary brain tumor with poor prognosis, short survival time post-diagnosis and high recurrence. Currently, no cure for GBM exists. The identification of an effective therapeutic modality for GBM remains a high priority amongst medical professionals and researches. In recent studies, inhalant cannabidiol (CBD) has demonstrated promise in effectively inhibiting GBM tumor growth. However, exactly how CBD treatment affects the physiology of these tumor cells remains unclear. Stress granules (SG) (a sub-class of biomolecular condensates (BMC)) are dynamic, membrane-less intracellular microstructures which contain proteins and nucleic acids. The formation and signaling of SGs and BMCs plays a significant role in regulating malignancies. This study investigates whether inhaled CBD may play an intervening role towards SGs in GBM tumor cells. Integrated bioinformatics approaches were preformed to gain further insights. This includes use of Immunohistochemistry and flow cytometry to measure SGs, as well as expression and phosphorylation of eukaryotic initiation factor-2α (eIF2α). The findings of this study reveal that CBD receptors (and co-regulated genes) have the potential to play an important biological role in the formation of BMCs within GBM. In this experiment, CBD treatment significantly increased the volume of TIAR-1. This increase directly correlated with elevation in both eIF2α expression and p-eIF2α in CBD treated tissues in comparison to the placebo group (p < 0.05). These results suggest that inhalant CBD significantly up-regulated SGs in GBM, and thus support a theory of targeting BMCs as a potential therapeutic substrate for treating GBM.

Glioblastoma stem cells deliver ABCB4 transcribed by ATF3 via exosomes conferring glioblastoma resistance to temozolomide.

Glioblastoma stem cells (GSCs) play a key role in glioblastoma (GBM) resistance to temozolomide (TMZ) chemotherapy. With the increase in research on the tumour microenvironment, exosomes secreted by GSCs have become a new focus in GBM research. However, the molecular mechanism by which GSCs affect drug resistance in GBM cells via exosomes remains unclear. Using bioinformatics analysis, we identified the specific expression of ABCB4 in GSCs. Subsequently, we established GSC cell lines and used ultracentrifugation to extract secreted exosomes. We conducted in vitro and in vivo investigations to validate the promoting effect of ABCB4 and ABCB4-containing exosomes on TMZ resistance. Finally, to identify the transcription factors regulating the transcription of ABCB4, we performed luciferase assays and chromatin immunoprecipitation-quantitative PCR. Our results indicated that ABCB4 is highly expressed in GSCs. Moreover, high expression of ABCB4 promoted the resistance of GSCs to TMZ. Our study found that GSCs can also transmit their highly expressed ABCB4 to differentiated glioma cells (DGCs) through exosomes, leading to high expression of ABCB4 in these cells and promoting their resistance to TMZ. Mechanistic studies have shown that the overexpression of ABCB4 in GSCs is mediated by the transcription factor ATF3. In conclusion, our results indicate that GSCs can confer resistance to TMZ in GBM by transmitting ABCB4, which is transcribed by ATF3, through exosomes. This mechanism may lead to drug resistance and recurrence of GBM. These findings contribute to a deeper understanding of the mechanisms underlying drug resistance in GBM and provide novel insights into its treatment.

VEGFR2 blockade inhibits glioblastoma cell proliferation by enhancing mitochondrial biogenesis.

BACKGROUND: Glioblastoma is an aggressive brain tumor linked to significant angiogenesis and poor prognosis. Anti-angiogenic therapies with vascular endothelial growth factor receptor 2 (VEGFR2) inhibition have been investigated as an alternative glioblastoma treatment. However, little is known about the effect of VEGFR2 blockade on glioblastoma cells per se. METHODS: VEGFR2 expression data in glioma patients were retrieved from the public database TCGA. VEGFR2 intervention was implemented by using its selective inhibitor Ki8751 or shRNA. Mitochondrial biogenesis of glioblastoma cells was assessed by immunofluorescence imaging, mass spectrometry, and western blot analysis. RESULTS: VEGFR2 expression was higher in glioma patients with higher malignancy (grade III and IV). VEGFR2 inhibition hampered glioblastoma cell proliferation and induced cell apoptosis. Mass spectrometry and immunofluorescence imaging showed that the anti-glioblastoma effects of VEGFR2 blockade involved mitochondrial biogenesis, as evidenced by the increases of mitochondrial protein expression, mitochondria mass, mitochondrial oxidative phosphorylation (OXPHOS), and reactive oxygen species (ROS) production, all of which play important roles in tumor cell apoptosis, growth inhibition, cell cycle arrest and cell senescence. Furthermore, VEGFR2 inhibition exaggerated mitochondrial biogenesis by decreased phosphorylation of AKT and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), which mobilized PGC1α into the nucleus, increased mitochondrial transcription factor A (TFAM) expression, and subsequently enhanced mitochondrial biogenesis. CONCLUSIONS: VEGFR2 blockade inhibits glioblastoma progression via AKT-PGC1α-TFAM-mitochondria biogenesis signaling cascade, suggesting that VEGFR2 intervention might bring additive therapeutic values to anti-glioblastoma therapy.

Gedunin modulates cellular growth and apoptosis in glioblastoma cell lines.

BACKGROUND: Glioblastomas are characterized by aggressive behavior. Surgery, radiotherapy, and alkylating agents, including temozolomide are the most common treatment options for glioblastoma. Often, conventional therapies fail to treat these tumors since they develop drug resistance. There is a need for newer agents to combat this deadly tumor. Natural products such as gedunin have shown efficacy in several human diseases. A comprehensive study of gedunin, an heat shock protein (HSP)90 inhibitor, has not been thoroughly investigated in glioblastoma cell lines with different genetic modifications. AIMS: A key objective of this study was to determine how gedunin affects the biological and signaling mechanisms in glioblastoma cells, and to determine how those mechanisms affect the proliferation and apoptosis of glioblastoma cells. METHODS: The viability potentials of gedunin were tested using MTT, cell counts, and wound healing assays. Gedunin's effects on glioma cells were further validated using LDH and colony formation assays. In addition, we investigated the survival and apoptotic molecular signaling targets perturbed by gedunin using Western blot analysis and flow cytometry. RESULTS: Our results show that there was a reduction in cell viability and inhibition of wound healing in the cells tested. Western blot analysis of the gene expression data revealed genes such as EGFR and mTOR/Akt/NF kappa B to be associated with gedunin sensitivity. Gedunin treatment induced apoptosis by cleaving poly ADP-ribose polymerase, activating caspases, and downregulating BCL-xL. Based on these results, gedunin suppressed cell growth and HSP client proteins, resulting in apoptosis in glioblastoma cell lines. CONCLUSION: Our data provide in vitro support for the anticancer activity of gedunin in glioma cells by downregulating cancer survival proteins.

Artificial neural network identified a 20-gene panel in predicting immunotherapy response and survival benefits after anti-PD1/PD-L1 treatment in glioblastoma patients.

BACKGROUND: Immune checkpoint inhibitors (ICIs) are a promising immunotherapy approach, but glioblastoma clinical trials have not yielded satisfactory results. OBJECTIVE: To screen glioblastoma patients who may benefit from immunotherapy. METHODS: Eighty-one patients receiving anti-PD1/PD-L1 treatment from a large-scale clinical trial and 364 patients without immunotherapy from The Cancer Genome Atlas (TCGA) were included. Patients in the ICI-treated cohort were divided into responders and nonresponders according to overall survival (OS), and the most critical responder-relevant features were screened using random forest (RF). We constructed an artificial neural network (ANN) model and verified its predictive value with immunotherapy response and OS. RESULTS: We defined two groups of ICI-treated glioblastoma patients with large differences in survival benefits as nonresponders (OS ≤6 months, n = 18) and responders (OS ≥17 months, n = 8). No differentially mutated genes were observed between responders and nonresponders. We performed RF analysis to select the most critical responder-relevant features and developed an ANN with 20 input variables, five hidden neurons and one output neuron. Receiver operating characteristic analysis and the DeLong test demonstrated that the ANN had the best performance in predicting responders, with an AUC of 0.97. Survival analysis indicated that ANN-predicted responders had significantly better OS rates than nonresponders. CONCLUSION: The 20-gene panel developed by the ANN could be a promising biomarker for predicting immunotherapy response and prognostic benefits in ICI-treated GBM patients and may guide oncologists to accurately select potential responders for the preferential use of ICIs.

PPAR-γ agonists reactivate the ALDOC-NR2F1 axis to enhance sensitivity to temozolomide and suppress glioblastoma progression.

Glioblastoma (GBM) is a type of brain cancer categorized as a high-grade glioma. GBM is characterized by limited treatment options, low patient survival rates, and abnormal serotonin metabolism. Previous studies have investigated the tumor suppressor function of aldolase C (ALDOC), a glycolytic enzyme in GBM. However, it is unclear how ALDOC regulates production of serotonin and its associated receptors, HTRs. In this study, we analyzed ALDOC mRNA levels and methylation status using sequencing data and in silico datasets. Furthermore, we investigated pathways, phenotypes, and drug effects using cell and mouse models. Our results suggest that loss of ALDOC function in GBM promotes tumor cell invasion and migration. We observed that hypermethylation, which results in loss of ALDOC expression, is associated with serotonin hypersecretion and the inhibition of PPAR-γ signaling. Using several omics datasets, we present evidence that ALDOC regulates serotonin levels and safeguards PPAR-γ against serotonin metabolism mediated by 5-HT, which leads to a reduction in PPAR-γ expression. PPAR-γ activation inhibits serotonin release by HTR and diminishes GBM tumor growth in our cellular and animal models. Importantly, research has demonstrated that PPAR-γ agonists prolong animal survival rates and increase the efficacy of temozolomide in an orthotopic brain model of GBM. The relationship and function of the ALDOC-PPAR-γ axis could serve as a potential prognostic indicator. Furthermore, PPAR-γ agonists offer a new treatment alternative for glioblastoma multiforme (GBM).

The microtubule targeting agent ST-401 triggers cell death in interphase and prevents the formation of polyploid giant cancer cells.

Microtubule targeting agents (MTAs) are commonly prescribed to treat cancers and predominantly kill cancer cells in mitosis. Significantly, some MTA-treated cancer cells escape death in mitosis, exit mitosis and become malignant polyploid giant cancer cells (PGCC). Considering the low number of cancer cells undergoing mitosis in tumor tissues, killing them in interphase may represent a favored antitumor approach. We discovered that ST-401, a mild inhibitor of microtubule (MT) assembly, preferentially kills cancer cells in interphase as opposed to mitosis, a cell death mechanism that avoids the development of PGCC. Single cell RNA sequencing identified mRNA transcripts regulated by ST-401, including mRNAs involved in ribosome and mitochondrial functions. Accordingly, ST-401 induces a transient integrated stress response, reduces energy metabolism, and promotes mitochondria fission. This cell response may underly death in interphase and avoid the development of PGCC. Considering that ST-401 is a brain-penetrant MTA, we validated these results in glioblastoma cell lines and found that ST-401 also reduces energy metabolism and promotes mitochondria fission in GBM sensitive lines. Thus, brain-penetrant mild inhibitors of MT assembly, such as ST-401, that induce death in interphase through a previously unanticipated antitumor mechanism represent a potentially transformative new class of therapeutics for the treatment of GBM.

Association of 5-aminolevulinic acid fluorescence guided resection with photodynamic therapy in recurrent glioblastoma: a matched cohort study.

PURPOSE: Glioblastoma is a malignant and aggressive brain tumour that, although there have been improvements in the first line treatment, there is still no consensus regarding the best standard of care (SOC) upon its inevitable recurrence. There are novel adjuvant therapies that aim to improve local disease control. Nowadays, the association of intraoperative photodynamic therapy (PDT) immediately after a 5-aminolevulinic acid (5-ALA) fluorescence-guided resection (FGR) in malignant gliomas surgery has emerged as a potential and feasible strategy to increase the extent of safe resection and destroy residual tumour in the surgical cavity borders, respectively. OBJECTIVES: To assess the survival rates and safety of the association of intraoperative PDT with 5-ALA FGR, in comparison with a 5-ALA FGR alone, in patients with recurrent glioblastoma. METHODS: This article describes a matched-pair cohort study with two groups of patients submitted to 5-ALA FGR for recurrent glioblastoma. Group 1 was a prospective series of 11 consecutive cases submitted to 5-ALA FGR plus intraoperative PDT; group 2 was a historical series of 11 consecutive cases submitted to 5-ALA FGR alone. Age, sex, Karnofsky performance scale (KPS), 5-ALA post-resection status, T1-contrast-enhanced extent of resection (EOR), previous and post pathology, IDH (Isocitrate dehydrogenase), Ki67, previous and post treatment, brain magnetic resonance imaging (MRI) controls and surgical complications were documented. RESULTS: The Mantel-Cox test showed a significant difference between the survival rates (p = 0.008) of both groups. 4 postoperative complications occurred (36.6%) in each group. As of the last follow-up (January 2024), 7/11 patients in group 1, and 0/11 patients in group 2 were still alive. 6- and 12-months post-treatment, a survival proportion of 71,59% and 57,27% is expected in group 1, versus 45,45% and 9,09% in group 2, respectively. 6 months post-treatment, a progression free survival (PFS) of 61,36% and 18,18% is expected in group 1 and group 2, respectively. CONCLUSION: The association of PDT immediately after 5-ALA FGR for recurrent malignant glioma seems to be associated with better survival without additional or severe morbidity. Despite the need for larger, randomized series, the proposed treatment is a feasible and safe addition to the reoperation.

The Potential of the Fibronectin Inhibitor Arg-Gly-Asp-Ser in the Development of Therapies for Glioblastoma.

Glioblastoma (GBM) is the most lethal and common malignant primary brain tumor in adults. An important feature that supports GBM aggressiveness is the unique composition of its extracellular matrix (ECM). Particularly, fibronectin plays an important role in cancer cell adhesion, differentiation, proliferation, and chemoresistance. Thus, herein, a hydrogel with mechanical properties compatible with the brain and the ability to disrupt the dynamic and reciprocal interaction between fibronectin and tumor cells was produced. High-molecular-weight hyaluronic acid (HMW-HA) functionalized with the inhibitory fibronectin peptide Arg-Gly-Asp-Ser (RGDS) was used to produce the polymeric matrix. Liposomes encapsulating doxorubicin (DOX) were also included in the hydrogel to kill GBM cells. The resulting hydrogel containing liposomes with therapeutic DOX concentrations presented rheological properties like a healthy brain. In vitro assays demonstrated that unmodified HMW-HA hydrogels only caused GBM cell killing after DOX incorporation. Conversely, RGDS-functionalized hydrogels displayed per se cytotoxicity. As GBM cells produce several proteolytic enzymes capable of disrupting the peptide-HA bond, we selected MMP-2 to illustrate this phenomenon. Therefore, RGDS internalization can induce GBM cell apoptosis. Importantly, RGDS-functionalized hydrogel incorporating DOX efficiently damaged GBM cells without affecting astrocyte viability, proving its safety. Overall, the results demonstrate the potential of the RGDS-functionalized hydrogel to develop safe and effective GBM treatments.

USP19 regulates DNA methylation damage repair and confers temozolomide resistance through MGMT stabilization.

OBJECTIVE: To elucidate the relationship between USP19 and O(6)-methylguanine-DNA methyltransferase (MGMT) after temozolomide treatment in glioblastoma (GBM) patients with chemotherapy resistance. METHODS: Screening the deubiquitinase pannel and identifying the deubiquitinase directly interacts with and deubiquitination MGMT. Deubiquitination assay to confirm USP19 deubiquitinates MGMT. The colony formation and tumor growth study in xenograft assess USP19 affects the GBM sensitive to TMZ was performed by T98G, LN18, U251, and U87 cell lines. Immunohistochemistry staining and survival analysis were performed to explore how USP19 is correlated to MGMT in GBM clinical management. RESULTS: USP19 removes the ubiquitination of MGMT to facilitate the DNA methylation damage repair. Depletion of USP19 results in the glioblastoma cell sensitivity to temozolomide, which can be rescued by overexpressing MGMT. USP19 is overexpressed in glioblastoma patient samples, which positively correlates with the level of MGMT protein and poor prognosis in these patients. CONCLUSION: The regulation of MGMT ubiquitination by USP19 plays a critical role in DNA methylation damage repair and GBM patients' temozolomide chemotherapy response.

Maximal cardiopulmonary exercise testing in glioblastoma patients undergoing chemotherapy: assessment of feasibility, safety, and physical fitness status.

PURPOSE: Maximal cardiopulmonary exercise testing (max. CPET) provides the most accurate measurement of cardiorespiratory fitness. However, glioblastoma (GBM) patients often undergo less intensive tests, e.g., 6-min walk test or self-rating scales. This study aims to demonstrate feasibility and safety of max. CPET in GBM patients, concurrently evaluating their physical fitness status. METHODS: Newly diagnosed GBM patients undergoing adjuvant chemotherapy were offered participation in an exercise program. At baseline, max. CPET assessed cardiorespiratory fitness including peak oxygen consumption (VO2peak), peak workload, and physical work capacity (PWC) at 75% of age-adjusted maximal heart rate (HR). Criteria for peak workload were predefined based on threshold values in HR, respiratory quotient, respiratory equivalent, lactate, and rate of perceived effort. Data were compared to normative values. Adverse events were categorized according to standardized international criteria. Further, self-reported exercise data pre- and post-diagnosis were gathered. RESULTS: All 36 patients (median-aged 60; 21 men) met the predefined criteria for peak workload. Mean absolute VO2peak was 1750 ± 529 ml/min, peak workload averaged 130 ± 43 W, and mean PWC was 0.99 ± 0.38 W/kg BW, all clinically meaningful lower than age- and sex-predicted normative values (87%, 79%, 90%, resp.). Only once (3%) a minor, transient side effect occurred (post-test dizziness, no intervention needed). Self-reported exercise decreased from 15.8 MET-h/week pre-diagnosis to 7.2 MET-h/week post-diagnosis. CONCLUSION: Max. CPET in this well-defined population proved feasible and safe. GBM patients exhibit reduced cardiorespiratory fitness, indicating the need for tailored exercise to enhance health and quality of life. CPET could be essential in establishing precise exercise guidelines.

Linagliptin decreased the tumor progression on glioblastoma model.

PURPOSE: Dipeptidyl peptidase-4 (DPP-4) inhibitors are oral hypoglycemic drugs and are used for type II diabetes. Previous studies showed that DPP-4 expression is observed in several tumor types and DPP-4 inhibitors suppress the tumor progression on murine tumor models. In this study, we evaluated the role of DPP-4 and the antitumor effect of a DPP-4 inhibitor, linagliptin, on glioblastoma (GBM). METHODS: We analyzed DPP-4 expression in glioma patients by the public database. We also analyzed DPP-4 expression in GBM cells and the murine GBM model. Then, we evaluated the cell viability, cell proliferation, cell migration, and expression of some proteins on GBM cells with linagliptin. Furthermore, we evaluated the antitumor effect of linagliptin in the murine GBM model. RESULTS: The upregulation of DPP-4 expression were observed in human GBM tissue and murine GBM model. In addition, DPP-4 expression levels were found to positively correlate with the grade of glioma patients. Linagliptin suppressed cell viability, cell proliferation, and cell migration in GBM cells. Linagliptin changed the expression of phosphorylated NF-kB, cell cycle, and cell adhesion-related proteins. Furthermore, oral administration of linagliptin decreases the tumor progression in the murine GBM model. CONCLUSION: Inhibition of DPP-4 by linagliptin showed the antitumor effect on GBM cells and the murine GBM model. The antitumor effects of linagliptin is suggested to be based on the changes in the expression of several proteins related to cell cycle and cell adhesion via the regulation of phosphorylated NF-kB. This study suggested that DPP-4 inhibitors could be a new therapeutic strategy for GBM.

RAPID resistance to BET inhibitors is mediated by FGFR1 in glioblastoma.

Bromodomain and extra-terminal domain (BET) proteins are therapeutic targets in several cancers including the most common malignant adult brain tumor glioblastoma (GBM). Multiple small molecule inhibitors of BET proteins have been utilized in preclinical and clinical studies. Unfortunately, BET inhibitors have not shown efficacy in clinical trials enrolling GBM patients. One possible reason for this may stem from resistance mechanisms that arise after prolonged treatment within a clinical setting. However, the mechanisms and timeframe of resistance to BET inhibitors in GBM is not known. To identify the temporal order of resistance mechanisms in GBM we performed quantitative proteomics using multiplex-inhibitor bead mass spectrometry and demonstrated that intrinsic resistance to BET inhibitors in GBM treatment occurs rapidly within hours and involves the fibroblast growth factor receptor 1 (FGFR1) protein. Additionally, small molecule inhibition of BET proteins and FGFR1 simultaneously induces synergy in reducing GBM tumor growth in vitro and in vivo. Further, FGFR1 knockdown synergizes with BET inhibitor mediated reduction of GBM cell proliferation. Collectively, our studies suggest that co-targeting BET and FGFR1 may dampen resistance mechanisms to yield a clinical response in GBM.

Identification of hypoxic macrophages in glioblastoma with therapeutic potential for vasculature normalization.

Monocyte-derived tumor-associated macrophages (Mo-TAMs) intensively infiltrate diffuse gliomas with remarkable heterogeneity. Using single-cell transcriptomics, we chart a spatially resolved transcriptional landscape of Mo-TAMs across 51 patients with isocitrate dehydrogenase (IDH)-wild-type glioblastomas or IDH-mutant gliomas. We characterize a Mo-TAM subset that is localized to the peri-necrotic niche and skewed by hypoxic niche cues to acquire a hypoxia response signature. Hypoxia-TAM destabilizes endothelial adherens junctions by activating adrenomedullin paracrine signaling, thereby stimulating a hyperpermeable neovasculature that hampers drug delivery in glioblastoma xenografts. Accordingly, genetic ablation or pharmacological blockade of adrenomedullin produced by Hypoxia-TAM restores vascular integrity, improves intratumoral concentration of the anti-tumor agent dabrafenib, and achieves combinatorial therapeutic benefits. Increased proportion of Hypoxia-TAM or adrenomedullin expression is predictive of tumor vessel hyperpermeability and a worse prognosis of glioblastoma. Our findings highlight Mo-TAM diversity and spatial niche-steered Mo-TAM reprogramming in diffuse gliomas and indicate potential therapeutics targeting Hypoxia-TAM to normalize tumor vasculature.

A Novel Approach for Glioblastoma Treatment by Combining Apoptosis Inducers (TMZ, MTX, and Cytarabine) with E.V.A. (Eltanexor, Venetoclax, and A1210477) Inhibiting XPO1, Bcl-2, and Mcl-1.

Adjuvant treatment for Glioblastoma Grade 4 with Temozolomide (TMZ) inevitably fails due to therapeutic resistance, necessitating new approaches. Apoptosis induction in GB cells is inefficient, due to an excess of anti-apoptotic XPO1/Bcl-2-family proteins. We assessed TMZ, Methotrexate (MTX), and Cytarabine (Ara-C) (apoptosis inducers) combined with XPO1/Bcl-2/Mcl-1-inhibitors (apoptosis rescue) in GB cell lines and primary GB stem-like cells (GSCs). Using CellTiter-Glo® and Caspase-3 activity assays, we generated dose-response curves and analyzed the gene and protein regulation of anti-apoptotic proteins via PCR and Western blots. Optimal drug combinations were examined for their impact on the cell cycle and apoptosis induction via FACS analysis, paralleled by the assessment of potential toxicity in healthy mouse brain slices. Ara-C and MTX proved to be 150- to 10,000-fold more potent in inducing apoptosis than TMZ. In response to inhibitors Eltanexor (XPO1; E), Venetoclax (Bcl-2; V), and A1210477 (Mcl-1; A), genes encoding for the corresponding proteins were upregulated in a compensatory manner. TMZ, MTX, and Ara-C combined with E, V, and A evidenced highly lethal effects when combined. As no significant cell death induction in mouse brain slices was observed, we conclude that this drug combination is effective in vitro and expected to have low side effects in vivo.

Targeting of REST with rationally-designed small molecule compounds exhibits synergetic therapeutic potential in human glioblastoma cells.

BACKGROUND: Glioblastoma (GBM) is an aggressive brain cancer associated with poor prognosis, intrinsic heterogeneity, plasticity, and therapy resistance. In some GBMs, cell proliferation is fueled by a transcriptional regulator, repressor element-1 silencing transcription factor (REST). RESULTS: Using CRISPR/Cas9, we identified GBM cell lines dependent on REST activity. We developed new small molecule inhibitory compounds targeting small C-terminal domain phosphatase 1 (SCP1) to reduce REST protein level and transcriptional activity in glioblastoma cells. Top leads of the series like GR-28 exhibit potent cytotoxicity, reduce REST protein level, and suppress its transcriptional activity. Upon the loss of REST protein, GBM cells can potentially compensate by rewiring fatty acid metabolism, enabling continued proliferation. Combining REST inhibition with the blockade of this compensatory adaptation using long-chain acyl-CoA synthetase inhibitor Triacsin C demonstrated substantial synergetic potential without inducing hepatotoxicity. CONCLUSIONS: Our results highlight the efficacy and selectivity of targeting REST alone or in combination as a therapeutic strategy to combat high-REST GBM.

New Avenues and Major Achievements in Phytocompounds Research for Glioblastoma Therapy.

Phytocompounds have been evaluated for their anti-glioblastoma actions for decades, with promising results from preclinical studies but only limited translation into clinics. Indeed, by targeting multiple signaling pathways deregulated in cancer, they often show high efficacy in the in vitro studies, but their poor bioavailability, low tumor accumulation, and rapid clearance compromise their efficacy in vivo. Here, we present the new avenues in phytocompound research for the improvement of glioblastoma therapy, including the ways to enhance the response to temozolomide using phytochemicals, the current focus on phytocompound-based immunotherapy, or the use of phytocompounds as photosensitizers in photodynamic therapy. Moreover, we present new, intensively evaluated approaches, such as chemical modifications of phytochemicals or encapsulation into numerous types of nanoformulations, to improve their bioavailability and delivery to the brain. Finally, we present the clinical trials evaluating the role of phytocompounds or phytocompound-derived drugs in glioblastoma therapy and the less studied phytocompounds or plant extracts that have only recently been found to possess promising anti-glioblastoma properties. Overall, recent advancements in phytocompound research are encouraging; however, only with more 3D glioblastoma models, in vivo studies, and clinical trials it is possible to upgrade the role of phytocompounds in glioblastoma treatment to a satisfactory level.

Synergistic Effect of a Combination of Proteasome and Ribonucleotide Reductase Inhibitors in a Biochemical Model of the Yeast Saccharomyces cerevisiae and a Glioblastoma Cell Line.

Proteasome inhibitors are used in the therapy of several cancers, and clinical trials are underway for their use in the treatment of glioblastoma (GBM). However, GBM becomes resistant to chemotherapy relatively rapidly. Recently, the overexpression of ribonucleotide reductase (RNR) genes was found to mediate therapy resistance in GBM. The use of combinations of chemotherapeutic agents is considered a promising direction in cancer therapy. The present work aimed to evaluate the efficacy of the combination of proteasome and RNR inhibitors in yeast and GBM cell models. We have shown that impaired proteasome function results in increased levels of RNR subunits and increased enzyme activity in yeast. Co-administration of the proteasome inhibitor bortezomib and the RNR inhibitor hydroxyurea was found to significantly reduce the growth rate of S. cerevisiae yeast. Accordingly, the combination of bortezomib and another RNR inhibitor gemcitabine reduced the survival of DBTRG-05MG compared to the HEK293 cell line. Thus, yeast can be used as a simple model to evaluate the efficacy of combinations of proteasome and RNR inhibitors.

Riluzole Reverses a Number of Undesirable Effects of Dexamethasone in Glioblastoma Cells.

BACKGROUND/AIM: Glioblastoma multiforme (GBM)-induced oedema is a major cause of morbidity and mortality among patients with GBM. Dexamethasone (Dex) is the most common corticosteroid used pre-operatively to control cerebral oedema in patients with GBM. Dex is associated with many side effects, and shorter overall survival and progression-free survival of patients with GBM. These negative effects of Dex highlight the need for combinational therapy. Riluzole (Ril), a drug used to treat amyotrophic lateral sclerosis (ALS), is thought to have potential as a treatment for various cancers, with clinical trials underway. Here, we investigated whether Ril could reverse some of the undesirable effects of Dex. MATERIALS AND METHODS: The effect of Dex, Ril, and Ril-Dex treatment on cell migration was monitored using the xCELLigence system. Cell viability assays were performed using 3-(4, 5-dimethylthiazol)-2, 5-diphenyltetrazolium bromide (MTT). The expression of genes involved in migration, glucose metabolism, and stemness was examined using real-time polymerase chain reaction (PCR). RESULTS: Pre-treating GBM cells with Ril reduced Dex-induced cell migration and altered Dex-induced effects on cell invasion, stem cell, and glucose metabolism markers. Furthermore, Ril remained effective in killing GBM cells in combination with Dex. CONCLUSION: Ril, which acts as an anti-tumorigenic drug, mediates some of the negative effects of Dex; therefore, it could be a potential drug to manage the side effects of Dex therapy in GBM.