Role of Redox Status in Development of Glioblastoma

Effects of thymoquinone and the curcumin analog EF-24 on the activity of the enzyme paraoxonase-1 in human glioblastoma cells U87MG

The spices and aromatic herbs were used not only in cooking to add flavour and smell to dishes but also for medicinal use. Nigella sativa, also called black cumin, is one of the species that contains an important bioactive component, thymoquinone (TQ), which has antioxidant, anti-inflammatory, antimicrobial, and antidiabetic effects. Curcuma longa, which also includes curcumin, has numerous anti-cancer properties. However, the bioavailability of curcumin is lower than that of its analogs. An analog of curcumin (EF-24), which has better bioavailability than curcumin, is capable of exerting a high anti-cancer effect. In our study, we determined the effects of PON1 enzyme activity on the proliferation and aggressiveness of glioblastoma cancer treated with TQ and EF-24 from lysates of the glioblastoma cell line U87MG. The results were determined as increased PON1 activity after treatment with TQ and EF-24 in the U87MG cell line (p < 0.0001).

Protective effects of silymarin in glioblastoma cancer cells through redox system regulation

BACKGROUND

Glioblastoma multiforme, a deadly form of brain tumor, is characterized by aggressive growth and poor prognosis. Oxidative stress, a disruption in the balance between antioxidants and oxidants, is a crucial factor in its pathogenesis. Silymarin, a flavonoid extracted from milk thistle, has shown therapeutic potential in inhibiting cancer cell growth, promoting apoptosis, and reducing inflammation. It also regulates oxidative stress. This study aims to investigate the regulatory effects of silymarin on oxidative stress parameters, especially the transcription factor Nrf2 and its related enzymes in GBM cancer cells, to develop a new anti-cancer compound with low toxicity.

METHODS AND RESULTS

First, the cytotoxicity of silymarin on U-87 MG cells was investigated by MTT and the results showed an IC50 of 264.6 μM. Then, some parameters of the redox system were measured with commercial kits, and the obtained results showed that silymarin increased the activity of catalase and superoxide dismutase enzymes, as well as the total antioxidant capacity levels; while the malondialdehyde level that is an indicator of lipid peroxidation was decreased by this compound. The expression level of Nrf2 and HO-1 and glutaredoxin and thioredoxin enzymes were checked by real-time PCR method, and the expression level increased significantly after treatment.

CONCLUSIONS

Our findings suggest that silymarin may exert its cytotoxic and anticancer effects by enhancing the Nrf2/HO-1 pathway through antioxidant mechanisms in U-87 MG cells.

The mitochondria-related gene risk mode revealed p66Shc as a prognostic mitochondria-related gene of glioblastoma

Numerous studies have highlighted the pivotal role of mitochondria-related genes (MRGs) in the initiation and progression of glioblastoma (GBM). However, the specific contributions of MRGs coding proteins to GBM pathology remain incompletely elucidated. The identification of prognostic MRGs in GBM holds promise for the development of personalized targeted therapies and the enhancement of patient prognosis. We combined differential expression with univariate Cox regression analysis to screen prognosis-associated MRGs in GBM. Based on the nine MRGs, the hazard ratio model was conducted using a multivariate Cox regression algorithm. SHC-related survival, pathway, and immune analyses in GBM cohorts were obtained from the Biomarker Exploration of the Solid Tumor database. The proliferation and migration of U87 cells were measured by CCK-8 and transwell assay. Apoptosis in U87 cells was evaluated using flow cytometry. Confocal microscopy was employed to measure mitochondrial reactive oxygen species (ROS) levels and morphology. The expression levels of SHC1 and other relevant proteins were examined via western blotting. We screened 15 prognosis-associated MRGs and constructed a 9 MRGs-based model. Validation of the model's risk score confirmed its efficacy in predicting the prognosis of patients with GBM. Furthermore, analysis revealed that SHC1, a constituent MRG of the prognostic model, was upregulated and implicated in the progression, migration, and immune infiltration of GBM. In vitro experiments elucidated that p66Shc, the longest isoform of SHC1, modulates mitochondrial ROS production and morphology, consequently promoting the proliferation and migration of U87 cells. The 9 MRGs-based prognostic model could predict the prognosis of GBM. SHC1 was upregulated and correlated with the prognosis of patients by involvement in immune infiltration. Furthermore, in vitro experiments demonstrated that p66Shc promotes U87 cell proliferation and migration by mediating mitochondrial ROS production. Thus, p66Shc may serve as a promising biomarker and therapeutic target for GBM.

Cysteine induces mitochondrial reductive stress in glioblastoma through hydrogen peroxide production

Glucose and amino acid metabolism are critical for glioblastoma (GBM) growth, but little is known about the specific metabolic alterations in GBM that are targetable with FDA-approved compounds. To investigate tumor metabolism signatures unique to GBM, we interrogated The Cancer Genome Atlas for alterations in glucose and amino acid signatures in GBM relative to other human cancers and found that GBM exhibits the highest levels of cysteine and methionine pathway gene expression of 32 human cancers. Treatment of patient-derived GBM cells with the FDA-approved single cysteine compound N-acetylcysteine (NAC) reduced GBM cell growth and mitochondrial oxygen consumption, which was worsened by glucose starvation. Normal brain cells and other cancer cells showed no response to NAC. Mechanistic experiments revealed that cysteine compounds induce rapid mitochondrial H2O2 production and reductive stress in GBM cells, an effect blocked by oxidized glutathione, thioredoxin, and redox enzyme overexpression. From analysis of the clinical proteomic tumor analysis consortium (CPTAC) database, we found that GBM cells exhibit lower expression of mitochondrial redox enzymes than four other cancers whose proteomic data are available in CPTAC. Knockdown of mitochondrial thioredoxin-2 in lung cancer cells induced NAC susceptibility, indicating the importance of mitochondrial redox enzyme expression in mitigating reductive stress. Intraperitoneal treatment of mice bearing orthotopic GBM xenografts with a two-cysteine peptide induced H2O2 in brain tumors in vivo. These findings indicate that GBM is uniquely susceptible to NAC-driven reductive stress and could synergize with glucose-lowering treatments for GBM.

Co-occurrence of glioma and multiple sclerosis: Prevailing theories and emerging therapies

Though the concurrence of primary brain tumors and multiple sclerosis (MS) is exceedingly rare, instances have been noted in the literature as early as 1949. Given these observations, researchers have proposed various ideas as to how these malignancies may be linked to MS. Due to insufficient data, none have gained traction or been widely accepted amongst neurologists or neuro-oncologists. What is abundantly clear, however, is the mounting uncertainty faced by clinicians when caring for these individuals. Concerns persist about the potential for disease modifying therapies (DMTs) to initiate or promote tumor growth and progression, and to date, there are no approved treatments capable of mitigating both MS disease activity and tumor growth, let alone established guidelines that clinicians may refer to. Collectively, these gaps in the literature impose limitations to optimizing the care and management of this population. As such, our hope is to stimulate further discussion of this topic and prompt future investigations to explore novel treatment options and advance our understanding of these concurrent disease processes. To this end, the chief objective of this article is to evaluate proposed ideas of how the diseases may be linked, outline emerging therapies for both MS and brain tumors, and describe evidence-based approaches to diagnosing and treating this patient population.

Engineering the glioblastoma microenvironment with bioactive nanoparticles for effective immunotherapy

While immunotherapies have revolutionized treatment for other cancers, glioblastoma multiforme (GBM) patients have not shown similar positive responses. The limited response to immunotherapies is partly due to the unique challenges associated with the GBM tumor microenvironment (TME), which promotes resistance to immunotherapies, causing many promising therapies to fail. There is, therefore, an urgent need to develop strategies that make the TME immune permissive to promote treatment efficacy. Bioactive nano-delivery systems, in which the nanoparticle, due to its chemical composition, provides the pharmacological function, have recently emerged as an encouraging option for enhancing the efficacy of immunotherapeutics. These systems are designed to overcome immunosuppressive mechanisms in the TME to improve the efficacy of a therapy. This review will discuss different aspects of the TME and how they impede therapy success. Then, we will summarize recent developments in TME-modifying nanotherapeutics and the in vitro models utilized to facilitate these advances.

Tumor microenvironment in a minipig model of spinal cord glioma

BACKGROUND

Spinal cord glioma (SCG) is considered an orphan disease that lacks effective treatment options with margins that are surgically inaccessible and an overall paucity of literature on the topic. The tumor microenvironment is a critical factor to consider in treatment and modeling design, especially with respect to the unresectable tumor edge. Recently, our group developed a high-grade spinal cord glioma (SCG) model in Göttingen minipigs.

METHODS

Immunofluorescence and ELISA were performed to explore the microenvironmental features and inflammation cytokines in this minipig SCG model. Protein carbonyl assay and GSH/GSSG assay were analyzed in the core and edge lesions in the minipig SCG model. The primary core and edge cells proliferation rate were shown in vitro, and the xenograft model in vivo.

RESULTS

We identified an elevated Ki-67 proliferative index, vascular and pericyte markers, CD31 and desmin in the tumor edge as compared to the tumor core. In addition, we found that the tumor edge demonstrated increased pro-inflammatory and gliomagenic cytokines including TNF-α, IL-1β, and IL-6. Furthermore, the mediation of oxidative stress is upregulated in the tumor edge. Hypoxic markers had statistically significant increased staining in the tumor core, but were notably still present in the tumor edge. The edge cells cultures derived from SCG biopsy also demonstrated an increased proliferative rate compared to core cell cultures in a xenotransplantation model.

CONCLUSIONS

Our study demonstrates heterogeneity in microenvironmental features in our minipig model of high-grade SCG, with a phenotype at the edge showing increased oxidative stress, proliferation, inflammatory cytokines, neovascularization, and decreased but present staining for hypoxic markers. These findings support the utility of this model as a means for investigating therapeutic approaches targeting the more aggressive and surgically unresectable tumor border.

Bioreducible Gene Delivery Platform that Promotes Intracellular Payload Release and Widespread Brain Dispersion

We here introduce a novel bioreducible polymer-based gene delivery platform enabling widespread transgene expression in multiple brain regions with therapeutic relevance following intracranial convection-enhanced delivery. Our bioreducible nanoparticles provide markedly enhanced gene delivery efficacy in vitro and in vivo compared to nonbiodegradable nanoparticles primarily due to the ability to release gene payloads preferentially inside cells. Remarkably, our platform exhibits competitive gene delivery efficacy in a neuron-rich brain region compared to a viral vector under previous and current clinical investigations with demonstrated positive outcomes. Thus, our platform may serve as an attractive alternative for the intracranial gene therapy of neurological disorders.

Outcomes of HSV-1 encephalitis infection in glioblastoma: An integrated systematic analysis

INTRODUCTION

Herpes Simplex Virus-1 (HSV-1) is a neurotropic DNA virus with neural latency and stereotypic viral encephalitis. It has been reported to conceal underlying glioblastoma (GBM) due to similar radiographic imaging and clinical presentation. Limited data exist on the co-occurrence of GBM and HSV-1. To better describe the pathophysiology of HSV-1 superinfections in GBM, we performed a comprehensive review of GBM cases with superimposed HSV-1.

METHODS

A comprehensive literature search of six electronic databases with apriori search criteria was performed to identify eligible cases of GBM with HSV-1. Relevant clinic-radiographic data were collected, Kaplan-Meier estimates, Fisher's exact test, and logistic regression analyses were used.

RESULTS

We identified 20 cases of HSE in GBM with an overall survival (OS) of 8.0 months. The median age of presentation was 63 years (range: 24-78 years) and the median interval between GBM or HSE diagnosis was 2 months (range: 0.05-25 months). HSE diagnosis before GBM diagnosis was a predictor for improved survival (HR: 0.06; 95% CI: [0.01-0.54]; p < 0.01). There is a significant reduction in OS in patients with concomitant HSE and GBM compared to the cancer genome atlas (TCGA) cohort (median OS: 8 months vs. 14.2 months; p < 0.05). Finally, HSV does not directly infect GBM cells but indirectly activates a local immune response in the tumor microenvironment.

CONCLUSIONS

Superimposed HSE in GBM may contribute to a significant reduction in OS compared to uninfected controls, potentially activating proto-oncogenes during active infection and latency. Preoperative HSE may induce an antiviral immune response, which may serve as a positive prognostic factor. Prompt antiviral treatment upon co-occurrence is necessary.

Ozone therapy for high-grade glioma: an overview

High-grade gliomas (grades III and IV) are highly malignant and aggressive brain tumors that present significant treatment challenges. Despite advances in surgery, chemotherapy, and radiation therapy, the prognosis for patients with glioma remains poor, with a median overall survival (mOS) range of 9-12 months. Therefore, exploring new and effective therapeutic strategies to improve glioma prognosis is of utmost importance and ozone therapy is a viable option. Ozone therapy has been used in various cancers, such as colon, breast, and lung, yielding significant results in preclinical studies and clinical trials. Only a few studies have been conducted on gliomas. Furthermore, since the metabolism of brain cells involves aerobic glycolysis, ozone therapy may improve the oxygen condition and enhance glioma radiation treatment. However, understanding the correct ozone dosage and optimal time of administration remains challenging. Herein, we hypothesize that ozone therapy should be more effective in gliomas compared with other tumors. This study provides an overview of the use of ozone therapy in high-grade glioma, including mechanisms of action, preclinical data, and clinical evidence.

Prognosis and Immune Landscapes in Glioblastoma Based on Gene-Signature Related to Reactive-Oxygen-Species

Glioblastoma (GBM) is the most malignant and aggressive primary brain tumor and is highly resistant to current therapeutic strategies. Previous studies have demonstrated that reactive oxygen species (ROS) play an important role in the regulation of signal transduction and immunosuppressive environment in GBM. To further study the role of ROS in prognosis, tumor micro-environment (TME) and immunotherapeutic response in GBM, an ROS-related nine-gene signature was constructed using the Lasso-Cox regression method and validated using three other datasets in our research, based on the hallmark ROS-pathway-related gene sets and the Cancer Genome Atlas GBM dataset. Differences in prognosis, TME scores, immune cell infiltration, immune checkpoint expression levels, and drug sensitivity between high-risk and low-risk subgroups were analyzed using R software. Collectively, our research uncovered a novel ROS-related prognostic model for primary GBM, which could prove to be a potential tool for clinical diagnosis of GBM, and help assess the immune and molecular characteristics of ROS in the tumorigenesis and immunosuppression of GBM. Our research also revealed that the expressions of ROS-related genes-HSPB1, LSP1, and PTX3-were closely related to the cell markers of tumor-associated macrophages (TAMs) and M2 macrophages validated by quantitative RT-PCR, suggesting them could be potential targets of immunotherapy for GBM.

Nucleic acid drug vectors for diagnosis and treatment of brain diseases

Nucleic acid drugs have the advantages of rich target selection, simple in design, good and enduring effect. They have been demonstrated to have irreplaceable superiority in brain disease treatment, while vectors are a decisive factor in therapeutic efficacy. Strict physiological barriers, such as degradation and clearance in circulation, blood-brain barrier, cellular uptake, endosome/lysosome barriers, release, obstruct the delivery of nucleic acid drugs to the brain by the vectors. Nucleic acid drugs against a single target are inefficient in treating brain diseases of complex pathogenesis. Differences between individual patients lead to severe uncertainties in brain disease treatment with nucleic acid drugs. In this Review, we briefly summarize the classification of nucleic acid drugs. Next, we discuss physiological barriers during drug delivery and universal coping strategies and introduce the application methods of these universal strategies to nucleic acid drug vectors. Subsequently, we explore nucleic acid drug-based multidrug regimens for the combination treatment of brain diseases and the construction of the corresponding vectors. In the following, we address the feasibility of patient stratification and personalized therapy through diagnostic information from medical imaging and the manner of introducing contrast agents into vectors. Finally, we take a perspective on the future feasibility and remaining challenges of vector-based integrated diagnosis and gene therapy for brain diseases.

Honey bee venom melittin increases the oxidant activity of cisplatin and kills human glioblastoma cells by stimulating the TRPM2 channel

Melittin (MLT) treatment is believed to enhance tumor cell death, apoptotic, and oxidative cytotoxic effects of cisplatin (CSP) via the modulation of Ca²⁺ channels in several cancer lines. The activation of TRPM2 mediated anticancer and CSP resistance actions via mitochondrial Ca²⁺ and Zn²⁺ accumulation-induced mitochondrial reactive free oxygen species (MitSOX) in the glioblastoma cells. The aim was to elucidate the effects of CSP and MLT combination via the TRPM2 stimulation on the tumor cell viability, cell number, cell death (propidium iodide/Hoechst rate), apoptosis, and MitSOX levels in the DBTRG-05MG cells. In the DBTRG-05MG cells, we induced four groups as control, MLT (2.5 μg/ml for 24 h), CSP (25 μM for 24 h), and CSP + MLT. The CSP-induced intracellular Ca²⁺ influxes to the TRPM2 activation were increased in the cells from coming H₂O₂ and ADP-Ribose. The influxes were decreased in the cells by the incubations of TRPM2 antagonists (ACA and carvacrol). The incubation of CSP increased the parameters of intracellular Ca²⁺ responses, mitochondria function, cytosolic free Zn²⁺ accumulation, apoptosis (caspase -3, -8, and -9), and MitSOX generation in the tumor cells. After the treatment of MLT with/without CSP, the parameters were further increased in the cells. In conclusion, the treatment of MLT increased the anticancer, tumor cell death, apoptotic, and oxidant effects of CSP in the glioblastoma tumor cells via activating the TRPM2. As a result, TRPM2 stimulation by MLT may be utilized as a successful agent in the CSP treatment of glioblastoma tumors.

Prospects for the use of blood elemental status to assess the molecular genetic profile of gliomas

It has been established that blood element homeostasis is related to gliomagenesis which increases the attractiveness of the analysis of its components as a promising preoperative mediated characteristics of the molecular genetic profile of gliomas. The aim of this work is to analyze the relationship between mineral metabolism parameters and immunohistochemical characteristics of glial tumors and evaluate the clinical significance of blood element homeostasis analysis for preoperative assessment of the molecular profile of gliomas. The levels of cancer specific markers MGMT, Ki-67, p-53, IDH1 were determined immunohistochemically using the corresponding antibody clones. Micronutrient levels were analyzed by inductively coupled plasma atomic emission spectrometry recalculating the results per 1 g of protein which was determined by the Lowry method. The data on cancer-specific marker levels obtained in primary brain tumors (20) and in blood plasma of gliomas patients (20) and practically healthy subjects (5) were compared using a number of statistical programs. We found significant differences in the levels of sodium, potassium, zinc and copper depending on the value of the mitotic index Ki-67 and IDH1 isocitrate dehydrogenase gene mutation. For the first time, a significant correlation showing the consistency between the level of glial tumor cancer-specific markers and blood mineral metabolism was observed. The revealed correlations provide new insights into understanding of gliomagenesis mechanisms and can be used as a predictive preoperative assessment of molecular genetic markers of gliomas.

Substrate stiffness effect on molecular crosstalk of epithelial-mesenchymal transition mediators of human glioblastoma cells

The complexity of the microenvironment effects on cell response, show accumulating evidence that glioblastoma (GBM) migration and invasiveness are influenced by the mechanical rigidity of their surroundings. The epithelial–mesenchymal transition (EMT) is a well-recognized driving force of the invasive behavior of cancer. However, the primary mechanisms of EMT initiation and progression remain unclear. We have previously showed that certain substrate stiffness can selectively stimulate human GBM U251-MG and GL15 glioblastoma cell lines motility. The present study unifies several known EMT mediators to uncover the reason of the regulation and response to these stiffnesses. Our results revealed that changing the rigidity of the mechanical environment tuned the response of both cell lines through change in morphological features, epithelial-mesenchymal markers (E-, N-Cadherin), EGFR and ROS expressions in an interrelated manner. Specifically, a stiffer microenvironment induced a mesenchymal cell shape, a more fragmented morphology, higher intracellular cytosolic ROS expression and lower mitochondrial ROS. Finally, we observed that cells more motile showed a more depolarized mitochondrial membrane potential. Unravelling the process that regulates GBM cells’ infiltrative behavior could provide new opportunities for identification of new targets and less invasive approaches for treatment.

CCAAT/Enhancer-Binding Protein Delta Regulates Glioblastoma Survival through Catalase-Mediated Hydrogen Peroxide Clearance

It has long been documented that cancer cells show increased and persistent oxidative stress due to increased reactive oxygen species (ROS), which is necessary for their increased proliferative rate. Due to the high levels of ROS, cancer cells also stimulate the antioxidant system, which includes the enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX), to eliminate ROS. However, overexpressed antioxidant enzymes often lead to drug resistance and therapeutic failure. Glioblastoma (GBM) is the most aggressive brain tumor and has the poorest prognosis. The transcription factor CCAAT/enhancer-binding protein delta (CEBPD) is highly expressed in GBM and correlates with drug resistance, prompting us to elucidate its role in GBM cell survival. In this study, we first demonstrated that loss of CEBPD significantly inhibited GBM cell viability and increased cell apoptosis. Furthermore, the expression of CAT was attenuated through promoter regulation following CEBPD knockdown, accelerating intracellular hydrogen peroxide (H₂O₂) accumulation. In addition, mitochondrial function was impaired in CEBPD knockdown cells. Together, we revealed the mechanism by which CEBPD-mediated CAT expression regulates H₂O₂ clearance for GBM cell survival.

Physical Training Protects Against Brain Toxicity in Mice Exposed to an Experimental Model of Glioblastoma

Glioma 261 (Gl261) cell-mediated neurotoxicity has been reported in previous studies examining glioblastoma (GBM), and the effects of physical exercise (PE) on this neurotoxicity have been poorly investigated. This study aimed to evaluate the effects of a PE program in animals with experimental GBM. Male C57BL/6J mice were randomized into sham or GBM groups and subjected to a PE program for four weeks. Gl261 cells were administered into the intraventricular region at 48 h after the last exercise session. Body weight, water and feed consumption, and behavior were all evaluated for 21 days followed by euthanasia. The right parietal lobe was removed for the analysis of glial fibrillary acidic protein (GFAP), epidermal growth factor receptor (EGFR), vimentin, C-myc, nuclear factor kappa B (NF-κB), tumor necrosis factor-alpha (TNF-α), interleukin 1 beta (IL-1β), interleukin 6 (IL-6), hydrogen peroxide, the glutathione system, and oxidative damage to proteins. The results revealed changes in the behavioral patterns of the trained animals, and no anatomopathological changes were observed in response to PE training. In contrast, animals with GBM subjected to PE exhibited lower immunoexpression of c-MYC, vimentin, and GFAP. Although experimental GBM altered the redox profile and inflammatory mediators, no significant alterations were observed after PE. In conclusion, our data provide consistent evidence of the relationship between PE and the improvement of tumorigenic parameters against the neurotoxicity of GL261 cells.

Molecular and Circulating Biomarkers in Patients with Glioblastoma

Glioblastoma is the most aggressive malignant tumor of the central nervous system with a low survival rate. The difficulty of obtaining this tumor material represents a major limitation, making the real-time monitoring of tumor progression difficult, especially in the events of recurrence or resistance to treatment. The identification of characteristic biomarkers is indispensable for an accurate diagnosis, the rigorous follow-up of patients, and the development of new personalized treatments. Liquid biopsy, as a minimally invasive procedure, holds promise in this regard. The purpose of this paper is to summarize the current literature regarding the identification of molecular and circulating glioblastoma biomarkers and the importance of their integration as a valuable tool to improve patient care.

Extraction and Optimization of Active Metabolites From Cluster Bean: An In Vitro Biological and Phytochemical Investigation

The current study aimed to explore active metabolites of locally recognized and high yielding cultivar cluster bean (BR-99) with a wide range of adaptability having antioxidant, antidiabetic, antimicrobial, and cytotoxic potential. Six solvents were used (crude methanol, n-hexane, chloroform, ethyl acetate, butanol, and aqueous) with escalating polarity for colorimetric determination of antioxidants such as total phenolic contents (TPC), total flavonoid contents (TFC), and free radical scavenging activity (FRSA) by DPPH (2, 2-diphenyl-1-picrylhydrazyl) assay. Moreover, an antidiabetic and anticancer study was conducted by α-amylase inhibition and MTT (3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-tetrazolium bromide) assay. Biological investigations were carried out against the most commonly found infectious microbial strains. The significant results (P ≤ .001) of each activity were seen among six tested solvent extracts. The ethyl acetate and methanol extract have more antioxidant potential with the highest TPC (16.38 ± .13 mg GAE/g) and TFC (8.15 ± .24 mg CE/g), respectively. Similarly, methanol extract presented the highest free radical scavenging activity (46.31 ± .91%), followed by ethyl acetate, butanol, chloroform, aqueous, and n-hexane extract. However, the maximum α-amylase inhibition (62.54 ± 1.47%) and anticancer activity against human lung cancer cells were congregated (78.31 ± 1.46%) in butanol and chloroform, respectively. A positive correlation was seen between TPC with TFC (R²= .8356), FRSA (R²= .8381), and anti-diabetic activity (R²= .8082), which highlights the phenolic contents as strong anti-oxidant agents especially flavonoids. Each extract of cluster bean (BR-99) showed significant antimicrobial activities for all tested bacterial strains except B. cereus and E. coli. The profound results of maximum antibacterial activity were witnessed by chloroform extract while ethyl acetate extracts showed great antifungal potential against all tested fungal strains. The HPLC quantitative analysis results of cluster bean (BR-99) revealed the presence of active phytochemicals such as gallic acid, HB acid, vanillic acid, kaempferol, sinapic acid, ferulic acid, salicylic acid, coumarins, quercetin, rutin, p-coumaric acid, and catechin, and the variation in both phytochemical and biological spectrums envisioned the cluster bean (BR-99) used in future as a cheap, safer, and potent source of bioactive drugs.

Comprehensive analysis of epigenetics regulation, prognostic and the correlation with immune infiltrates of GPX7 in adult gliomas

Gliomas are the most commonly occurring malignant brain tumor characterized by an immunosuppressive microenvironment accompanied by profound epigenetic changes, thus influencing the prognosis. Glutathione peroxidase 7 (GPX7) is essential for regulating reactive oxygen species homeostasis under oxidative stress. However, little is known about the function of GPX7 in gliomas. In this study, we hypothesized that GPX7 methylation status could influence biological functions and local immune responses that ultimately impact prognosis in adult gliomas. We conducted an integrated bioinformatics analysis mining GPX7 DNA methylation status, transcriptional and survival data of glioma patients. We discovered that GPX7 was remarkably increased in glioma tissues and cell lines, and was associated with poor prognosis. This upregulation was significantly linked to clinicopathological and molecular features, besides being expressed in a cell cycle-dependent manner. Our results consistently demonstrated that upregulation of GPX7 is tightly modulated by epigenetic processes, which also impacted the overall survival of patients with low-grade gliomas (LGG). Based on the analysis of biological functions, we found that GPX7 might be involved in immune mechanisms involving both innate and adaptive immunity, type I interferon production and regulation of synaptic transmission in LGG, whereas in GBM, it is mainly related to metabolic regulation of mitochondrial dynamics. We also found that GPX7 strongly correlates with immune cell infiltration and diverse immune cell markers, suggesting its role in tumor-specific immune response and in regulating the migration of immune cell types to the tumor microenvironment. Combining these multiple data, we provided the first evidence regarding the epigenetic-mediated regulatory mechanisms underlying GPX7 activation in gliomas. Furthermore, our study brings key insights into the significant effect of GPX7 in modulating both immune molecules and in immune cell infiltration in the microenvironment of gliomas, which might impact the patient outcome, opening up future opportunities to regulate the local immune response.

Eicosapentaenoic acid enhanced apoptotic and oxidant effects of cisplatin via activation of TRPM2 channel in brain tumor cells

Cisplatin (CiSP) induced-overload Ca²⁺ entry results in the increase of mitochondrial oxidative stress and apoptosis in the cancer cell. TRPM2 cation channel is gated by the cytosolic ADP-ribose (ADPR) and reactive oxygen species (ROS). The high content of polyunsaturated fatty acid (PUFA) in the brain is a main target of ROS. Eicosapentaenoic acid (EPA) induces oxidant action via the enhance of PUFA content in the glioblastoma (DBTRG) cells. We hypothesized that a combination of CiSP and EPA may offer a potential therapy in the DBTRG cell by exerting the antitumor, oxidant, and apoptotic actions and stimulating Ca²⁺ influx and TRPM2 activity. In the DBTRG cells, we induced four groups as control, EPA (30 μM for 24 h), CiSP (25 μM for 24 h), and CiSP + EPA. The CiSP-induced intracellular Ca²⁺ responses to the TRPM2 activation were increased in the DBTRG cells from coming H₂O₂ and ADPR. The responses were decreased in the cells by the inhibitions of TRPM2 (ACA and 2/APB) and PARP/1 (DPQ and PJ34). The incubation of EPA further increased the intracellular Ca²⁺ responses, mitochondria function, and the generation of ROS in the DBTRGs. After the treatment of EPA, lipid peroxidation, apoptosis, cell death, caspase -3, -8, and -9 levels were further increased in the cells, although the levels of glutathione, glutathione peroxidase, cell numbers, and viability were further decreased in the cells. In summary, anticancer, apoptotic, and oxidant actions of CiSP were further increased via the activation of TRPM2 channel in the DBTRGs. Hence, TRPM2 stimulation via EPA could be used as an effective agent in the treatment of glioblastoma tumors with CiSP.

Role of TRPM2 in brain tumours and potential as a drug target

Ion channels are ubiquitously expressed in almost all living cells, and are the third-largest category of drug targets, following enzymes and receptors. The transient receptor potential melastatin (TRPM) subfamily of ion channels are important to cell function and survival. Studies have shown upregulation of the TRPM family of ion channels in various brain tumours. Gliomas are the most prevalent form of primary malignant brain tumours with no effective treatment; thus, drug development is eagerly needed. TRPM2 is an essential ion channel for cell function and has important roles in oxidative stress and inflammation. In response to oxidative stress, ADP-ribose (ADPR) is produced, and in turn activates TRPM2 by binding to the NUDT9-H domain on the C-terminal. TRPM2 has been implicated in various cancers and is significantly upregulated in brain tumours. This article reviews the current understanding of TRPM2 in the context of brain tumours and overviews the effects of potential drug therapies targeting TRPM2 including hydrogen peroxide (H₂O₂), curcumin, docetaxel and selenium, paclitaxel and resveratrol, and botulinum toxin. It is long withstanding knowledge that gliomas are difficult to treat effectively, therefore investigating TRPM2 as a potential therapeutic target for brain tumours may be of considerable interest in the fields of ion channels and pharmacology.

Natural and Synthetic Agents Targeting Reactive Carbonyl Species against Metabolic Syndrome

Reactive carbonyl species (RCS) may originate from the oxidation of unsaturated fatty acids and sugar in conditions of pathology. They are known to have high reactivity towards DNA as well as nucleophilic sites of proteins, resulting in cellular dysfunction. It has been considered that various pathological conditions are associated with an increased level of RCS and their reaction products. Thus, regulating the levels of RCS may be associated with the mitigation of various metabolic and neurodegenerative disorders. In order to perform a comprehensive review, various literature databases, including MEDLINE, EMBASE, along with Google Scholar, were utilized to obtain relevant articles. The voluminous review concluded that various synthetic and natural agents are available or in pipeline research that hold tremendous potential to be used as a drug of choice in the therapeutic management of metabolic syndrome, including obesity, dyslipidemia, diabetes, and diabetes-associated complications of atherosclerosis, neuropathy, and nephropathy. From the available data, it may be emphasized that various synthetic agents, such as carnosine and simvastatin, and natural agents, such as polyphenols and terpenoids, can become a drug of choice in the therapeutic management for combating metabolic syndromes that involve RCS in their pathophysiology. Since the RCS are known to regulate the biological processes, future research warrants detailed investigations to decipher the precise mechanism.

Glioblastoma Cells Counteract PARP Inhibition through Pro-Survival Induction of Lipid Droplets Synthesis and Utilization

Simple Summary

Glioblastoma multiforme (GBM) is the most common and deadly primary brain tumor in adults and one of the most aggressive cancers. The use of Poly ADP-Ribose Polymerase (PARP) inhibitors is being expanded as therapeutic alternative in multiple types of cancer beyond BRCA1/2 mutant breast and ovarian cancer. Here we have analyzed glioma cells’ traits that limit the efficacy of PARPi as anti-glioma agents and we found that PARPi triggered the synthesis of lipid droplets (LDs) that fueled glioma cells by inducing pro-survival lipid consumption. Notably, blocking Fatty Acids utilization by inhibition of β-oxidation with etomoxir, increased PARPi-induced glioma cell death while treatment with oleic acid (OA) prevented the anti-glioma effect of PARPi. We uncover a novel mechanism by which glioblastoma escapes to anti-tumor agents through metabolic reprogramming, inducing the synthesis and utilization of LDs as a pro-survival strategy in response to PARP inhibition.

Abstract

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumor in adults. Poly (ADP-ribose) polymerase inhibitors (PARPi) represent a new class of anti-neoplastic drugs. In the current study, we have characterized the mechanism by which glioblastoma cells evade the effect of PARPi as anti-tumor agents. We have found that suppression of PARP activity exerts an anti-stemness effect and has a dual impact on autophagy, inducing its activation in the first 24 h (together with down-regulation of the pro-survival mTOR pathway) and preventing autophagosomes fusion to lysosomes at later time-points, in primary glioma cells. In parallel, PARPi triggered the synthesis of lipid droplets (LDs) through ACC-dependent activation of de novo fatty acids (FA) synthesis. Notably, inhibiting β-oxidation and blocking FA utilization, increased PARPi-induced glioma cell death while treatment with oleic acid (OA) prevented the anti-glioma effect of PARPi. Moreover, LDs fuel glioma cells by inducing pro-survival lipid consumption as confirmed by quantitation of oxygen consumption rates using Seahorse respirometry in presence or absence of OA. In summary, we uncover a novel mechanism by which glioblastoma escapes to anti-tumor agents through metabolic reprogramming, inducing the synthesis and utilization of LDs as a pro-survival strategy in response to PARP inhibition.

Regulation of reverse electron transfer at mitochondrial complex I by unconventional Notch action in cancer stem cells

Metabolic flexibility is a hallmark of many cancers where mitochondrial respiration is critically involved, but the molecular underpinning of mitochondrial control of cancer metabolic reprogramming is poorly understood. Here, we show that reverse electron transfer (RET) through respiratory chain complex I (RC-I) is particularly active in brain cancer stem cells (CSCs). Although RET generates ROS, NAD⁺/NADH ratio turns out to be key in mediating RET effect on CSC proliferation, in part through the NAD⁺-dependent Sirtuin. Mechanistically, Notch acts in an unconventional manner to regulate RET by interacting with specific RC-I proteins containing electron-transporting Fe-S clusters and NAD(H)-binding sites. Genetic and pharmacological interference of Notch-mediated RET inhibited CSC growth in Drosophila brain tumor and mouse glioblastoma multiforme (GBM) models. Our results identify Notch as a regulator of RET and RET-induced NAD⁺/NADH balance, a critical mechanism of metabolic reprogramming and a metabolic vulnerability of cancer that may be exploited for therapeutic purposes.

Targeting Glioblastoma via Selective Alteration of Mitochondrial Redox State

Simple Summary

Glioblastoma is characterized by a pronounced redox imbalance due to elevated glycolytic and mitochondrial oxidative metabolism. New therapeutic strategies have been developed to modulate glioblastoma redox signaling to effectively suppress growth and prolong survival. However, drug selectivity and therapeutic relapse prove to be the major challenges. We describe a pharmacological strategy for the selective targeting and treatment of glioblastoma using the redox active combination drug menadione/ascorbate, which is characterized by tolerance to normal cells and tissues. Menadione/ascorbate treatment of glioblastoma mice suppressed tumor growth and significantly increased survival without adverse side effects. This is accompanied by increased oxidative stress, decreased reducing capacity and decreased cellular density in the tumor alone, as well as increased brain perfusion and decreased regulation of several oncoproteins and oncometabolites, which implies modulation of the immune response and reduced drug resistance. We believe that this therapeutic strategy is feasible and promising and deserves the attention of clinicians.

Abstract

Glioblastoma is one of the most aggressive brain tumors, characterized by a pronounced redox imbalance, expressed in a high oxidative capacity of cancer cells due to their elevated glycolytic and mitochondrial oxidative metabolism. The assessment and modulation of the redox state of glioblastoma are crucial factors that can provide highly specific targeting and treatment. Our study describes a pharmacological strategy for targeting glioblastoma using a redox-active combination drug. The experiments were conducted in vivo on glioblastoma mice (intracranial model) and in vitro on cell lines (cancer and normal) treated with the redox cycling pair menadione/ascorbate (M/A). The following parameters were analyzed in vivo using MRI or ex vivo on tissue and blood specimens: tumor growth, survival, cerebral perfusion, cellular density, tissue redox state, expression of tumor-associated NADH oxidase (tNOX) and transforming growth factor-beta 1 (TGF-β1). Dose-dependent effects of M/A on cell viability, mitochondrial functionality, and redox homeostasis were evaluated in vitro. M/A treatment suppressed tumor growth and significantly increased survival without adverse side effects. This was accompanied by increased oxidative stress, decreased reducing capacity, and decreased cellular density in the tumor only, as well as increased cerebral perfusion and down-regulation of tNOX and TGF-β1. M/A induced selective cytotoxicity and overproduction of mitochondrial superoxide in isolated glioblastoma cells, but not in normal microglial cells. This was accompanied by a significant decrease in the over-reduced state of cancer cells and impairment of their “pro-oncogenic” functionality, assessed by dose-dependent decreases in: NADH, NAD⁺, succinate, glutathione, cellular reducing capacity, mitochondrial potential, steady-state ATP, and tNOX expression. The safety of M/A on normal cells was compromised by treatment with cerivastatin, a non-specific prenyltransferase inhibitor. In conclusion, M/A differentiates glioblastoma cells and tissues from normal cells and tissues by redox targeting, causing severe oxidative stress only in the tumor. The mechanism is complex and most likely involves prenylation of menadione in normal cells, but not in cancer cells, modulation of the immune response, a decrease in drug resistance, and a potential role in sensitizing glioblastoma to conventional chemotherapy.

Harnessing oxidative stress for anti-glioma therapy

Glioma cells use intermediate levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS) for growth and invasion, and suppressing these reactive molecules thus may compromise processes that are vital for glioma survival. Increased oxidative stress has been identified in glioma cells, in particular in glioma stem-like cells. Studies have shown that these cells harbor potent antioxidant defenses, although endogenous protection against nitrosative stress remains understudied. The enhancement of oxidative or nitrosative stress offers a potential target for triggering glioma cell death, but whether oxidative and nitrosative stresses can be combined for therapeutic effects requires further research. The optimal approach of harnessing oxidative stress for anti-glioma therapy should include the induction of free radical-induced oxidative damage and the suppression of antioxidant defense mechanisms selectively in glioma cells. However, selective induction of oxidative/nitrosative stress in glioma cells remains a therapeutic challenge, and research into selective drug delivery systems is ongoing. Because of multifactorial mechanisms of glioma growth, progression, and invasion, prospective oncological therapies may include not only therapeutic oxidative/nitrosative stress but also inhibition of oncogenic kinases, antioxidant molecules, and programmed cell death mediators.

Comprehensive analysis of the expression levels and prognostic values of PRDX family genes in glioma

Gliomas are a histologically and molecularly heterogeneous group of neoplasms accounting for 80% of malignant primary brain tumors. Growing evidence suggests that production of reactive oxygen species (ROS) is linked to glioma pathogenesis, although it is still unclear whether it is a cause or an effect of this process. Peroxiredoxins (PRDXs), a family of six antioxidant proteins, may promote or inhibit carcinogenesis, depending on the tumor type and stage. The current knowledge on their expression, regulation and functions in glioma is scarce. In this study, a comprehensive analysis of PRDXs expression in distinct glioma subtypes and non-tumor brain tissues was conducted using gene expression data from The Cancer Genome Atlas (TCGA), REpository for Molecular BRAin NeoplasiaDaTa (REMBRANDT), The Chinese Glioma Atlas (CGGA) and Gene Expression Omnibus (GEO) datasets. The association between gene expression and patient survival was investigated. DNA methylation, mutations, copy number alterations of deregulated PRDXs as well as the correlation between gene expression and tumor-infiltrating immune cells were assessed. The analysis revealed overexpression of PRDX1, PRDX4, and PRDX6 in most histological glioma types compared to the non-tumor tissues, while PRDX2, PRDX3 and PRDX5 expression remained unaltered. The expression of PRDX4 and PRDX6 was higher in mesenchymal than proneural and classical glioma subtypes. Moreover, lower expression of PRDX1, PRDX4 and PRDX6 was observed in tumors with a glioma CpG island methylator phenotype (G-CIMP) compared to non-G-CIMP tumors, as well as in isocitrate dehydrogenase (IDH) mutant and 1p/19q co-deleted gliomas compared to the wild-type counterparts. High expression of PRDX1, PRDX4 or PRDX6 correlated with poor survival of glioma patients. PRDX1 and PRDX6 displayed a positive correlation with different immune cell population in low grade gliomas and, to a lesser extent, in glioblastoma. PRDX1 expression exhibited negative correlation with DNA methylation. These results indicate that high expression of PRDX1, PRDX4 and PRDX6 is associated with poor outcome in gliomas.

Glutaredoxin 2 promotes SP-1-dependent CSPG4 transcription and migration of wound healing NG2 glia and glioma cells: Enzymatic Taoism

Redox regulation of specific cysteines via oxidoreductases of the thioredoxin family is increasingly being recognized as an important signaling pathway. Here, we demonstrate that the cytosolic isoform of the vertebrate-specific oxidoreductase Glutaredoxin 2 (Grx2c) regulates the redox state of the transcription factor SP-1 and thereby its binding affinity to both the promoter and an enhancer region of the CSPG4 gene encoding chondroitin sulfate proteoglycan nerve/glial antigen 2 (NG2). This leads to an increased number of NG2 glia during in vitro oligodendroglial differentiation and promotes migration of these wound healing cells. On the other hand, we found that the same mechanism also leads to increased invasion of glioma tumor cells. Using in vitro (human cell lines), ex vivo (mouse primary cells), and in vivo models (zebrafish), as well as glioblastoma patient tissue samples we provide experimental data highlighting the Yin and Yang of redox signaling in the central nervous system and the enzymatic Taoism of Grx2c.

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CSPG4 promoter binding of the transcription factor SP-1 depends on glutaredoxin 2

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Cytosolic glutaredoxin 2 promotes oligodendrocyte differentiation into NG2 glia

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Migration and wound healing capacity of NG2 glia is increased by glutaredoxin 2

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Glutaredoxin 2 increases invasion of human glioblastoma cells in vitro and in vivo

The SP/NK1R System-Mediated ROS Generation in GBM Cells through Inhibiting Glutaredoxin Protein

Altered redox balance is among the main contributing factors developing glioblastoma multiforme (GBM), a highly aggressive grade IV brain tumor. Neuropeptide substance P (SP) plays a key role in modifying the cellular redox environment by activating the neurokinin-1 receptor (NK1R). In this study, we aimed to investigate the redox-modulating properties of both SP and a commercially available NK1R antagonist, aprepitant in GBM cells. To detect the effect of aprepitant on the viability of U87 glioblastoma cells, resazurin assay was applied. The level of intracellular ROS was assessed using 2′,7′-dichlorodihydrofluorescein diacetate (H2DCFDA) assay. The expression of glutaredoxin, a well-known redox-active protein, was measured by quantitative real-time polymerase chain reaction (qRT-PCR). Concurrently, the activity of glutaredoxin was also analyzed by a commercial kit (ZellBio GmbH). We found that SP increased the intracellular levels of reactive oxygen species (ROS) in U87 GBM cells, and aprepitant remarkably decreased this effect. We also explored the effects of SP/NK1R signaling on the glutaredoxin system as a major cellular redox buffer in GBM cells. SP reduced both expression and enzymatic activity of glutaredoxin, and these effects were significantly decreased by aprepitant. In conclusion, our results suggest a possible involvement of SP/NK1R signaling in GBM pathogenesis through oxidative stress and offering new insight for the application of aprepitant as a redox-modulating strategy in GBM patients.

Recent developments in drug delivery strategies for targeting DNA damage response in glioblastoma

Glioblastoma is the most frequent and malignant brain tumor. The median survival for this disease is approximately 15 months, and despite all the available treatment strategies employed, it remains an incurable disease. Preclinical and clinical research have shown that the resistance process related to DNA damage repair pathways, glioma stem cells, blood-brain barrier selectivity, and dose-limiting toxicity of systemic treatment leads to poor clinical outcomes. In this context, the advent of drug delivery systems associated with localized treatment seems to be a promising and versatile alternative to overcome the failure of the current treatment approaches. In order to bypass therapeutic tumor resistance mechanisms, more effective combinatorial therapies should be identified, such as the use of cytotoxic drugs combined with the inhibition of DNA damage response (DDR)-related targets. Additionally, critical reasoning about the delivery approach and administration route in brain tumors treatment innovation is essential. The outcomes of future experimental studies regarding the association of delivery systems, alternative treatment routes, and DDR targets are expected to lead to the development of refined therapeutic interventions. Novel therapeutic approaches could improve the life's quality of glioblastoma patients and increase their survival rate.

The E3 Ubiquitin Ligase NEDD4-1 Mediates Temozolomide-Resistant Glioblastoma through PTEN Attenuation and Redox Imbalance in Nrf2-HO-1 Axis

BACKGROUND

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults. It is highly resistant to chemotherapy, and tumor recurrence is common. Neuronal precursor cell-expressed developmentally downregulated 4-1 (NEDD4-1) is an E3 ligase that controls embryonic development and animal growth. NEDD4-1 regulates the tumor suppressor phosphatase and tensin homolog (PTEN), one of the major regulators of the PI3K/AKT/mTOR signaling axis, as well as the response to oxidative stress.

METHODS

The expression levels of NEDD4-1 in GBM tissues and different cell lines were determined by quantitative real-time polymerase chain reaction and immunohistochemistry. In vitro and in vivo assays were performed to explore the biological effects of NEDD4-1 on GBM cells. Temozolomide (TMZ)-resistant U87MG and U251 cell lines were specifically established to determine NEDD4-1 upregulation and its effects on the tumorigenicity of GBM cells. Subsequently, miRNA expression in TMZ-resistant cell lines was investigated to determine the dysregulated miRNA underlying the overexpression of NEDD4-1. Indole-3-carbinol (I3C) was used to inhibit NEDD4-1 activity, and its effect on chemoresistance to TMZ was verified.

RESULTS

NEDD4-1 was significantly overexpressed in the GBM and TMZ-resistant cells and clinical samples. NEDD4-1 was demonstrated to be a key oncoprotein associated with TMZ resistance, inducing oncogenicity and tumorigenesis of TMZ-resistant GBM cells compared with TMZ-responsive cells. Mechanistically, TMZ-resistant cells exhibited dysregulated expression of miR-3129-5p and miR-199b-3p, resulting in the induced NEDD4-1 mRNA-expression level. The upregulation of NEDD4-1 attenuated PTEN expression and promoted the AKT/NRF2/HO-1 oxidative stress signaling axis, which in turn conferred amplified defense against reactive oxygen species (ROS) and eventually higher resistance against TMZ treatment. The combination treatment of I3C, a known inhibitor of NEDD4-1, with TMZ resulted in a synergistic effect and re-sensitized TMZ-resistant tumor cells both in vitro and in vivo.

CONCLUSIONS

These findings demonstrate the critical role of NEDD4-1 in regulating the redox imbalance in TMZ-resistant GBM cells via the degradation of PTEN and the upregulation of the AKT/NRF2/HO-1 signaling pathway. Targeting this regulatory axis may help eliminate TMZ-resistant glioblastoma.

The implications of nitric oxide metabolism in the treatment of glial tumors

Glial tumors are the most common intracranial malignancies. Unfortunately, despite such a high prevalence, patients' prognosis is usually poor. It is related to the high invasiveness, tendency to relapse and the resistance of tumors to traditional methods of treatment. An important link in the aspect of these issues may be nitric oxide (NO) metabolism. It is a very complex mechanism with multidirectional effects on the neoplastic process. Depending on the concentration axis, it can both exert pro-tumor action as well as contribute to the inhibition of tumorigenesis. The latest observations show that the control of its metabolism can be very helpful in the development of new methods of treating gliomas, as well as in increasing the effectiveness of the agents currently used. The influence of nitric oxide and nitric oxide synthase (NOS) activity on glioma stem cells seem to be of particular importance. The use of specific inhibitors may allow the reduction of tumor growth and its tendency to relapse. Another important feature of GSCs is their conditioning of glioma resistance to traditional forms of treatment. Recent studies have shown that modulation of NO metabolism can suppress this effect, preventing the induction of radio and chemoresistance. Moreover, nitric oxide is involved in the regulation of a number of immune mechanisms. Adequate modulation of its metabolism may contribute to the induction of an anti-tumor response in the patients' immune system.

Safety and Efficacy Assessments to Take Antioxidants in Glioblastoma Therapy: From In Vitro Experiences to Animal and Clinical Studies

Glioblastoma (GBM) is considered one of the most common malignant brain tumors, occurring as over 15% of all primary central nervous system and brain neoplasms. The unique and standard treatment option towards GBM involves the combination of surgical resection followed by radiotherapy (RT) and chemotherapy (CT). However, due to the aggressive nature and heterogeneity of GBMs, they remained difficult to treat. Recent findings from preclinical studies have revealed that disruption of the redox balance via using either oxidative or anti-oxidative agents in GBM presented an effective and promising therapeutic approach. A limited number of clinical trials substantially encouraged their concomitant use with RT or CT. Thus, treatment of GBMs may benefit from natural or synthetic antioxidative compounds as novel therapeutics. Despite the presence of variegated in vitro and in vivo studies focusing on safety and efficacy issues of these promising therapeutics, nowadays their translation to clinics is far from applicability due to several challenges. In this review, we briefly introduce the enzymatic and non-enzymatic antioxidant defense systems as well as potential signaling pathways related to the pathogenesis of GBM with a special interest in antioxidant mechanisms. In addition, we describe the advantages and limitations of antioxidant supplementation in GBM cases or disease models as well as growing challenges for GBM therapies with antioxidants in the future.

Oxygen Vacancy-Driven Reversible Free Radical Catalysis for Environment-Adaptive Cancer Chemodynamic Therapy

Amplifying free radical production by chemical dynamic catalysis to cause oxidative damage to cancer cells has received extensive interest for cancer-specific therapy. The major challenge is inevitable negative modulation on the tumor microenvironment (TME) by these species, hindering durable effectiveness. Here we show for the first time an oxygen vacancy-rich Bi-based regulator that allows environment-adaptive free radical catalysis. Specifically, the regulator catalyzes production of highly toxic O₂ ^.- and ^. OH in cancer cells via logic enzymatic reactions yet scavenges accumulation of free radicals and immunosuppressive mediators in TME-associated noncancerous cells. Atomic-level mechanistic studies reveal that such dual-modal regulating behavior is dominated by oxygen vacancies that well fit for free radical catalytic kinetics, along with distinguished cellular fates of this regulator. With this smart regulator, a "two birds with one shot" cancer dynamic therapy can be expected.

A metastasis suppressor Pt-dendrimer nanozyme for the alleviation of glioblastoma

Nanozymes are nanostructure-based materials which mimic the enzymatic characteristics of natural enzymes. Biological applications of nanozymes have been highlighted in basic research, industry, and translational medicine as a new cutting-edge tool. In this work, and for the first time, we disclose a tumor alleviation property of a nanozyme that is made up of amine-terminated sixth-generation polyamidoamine dendrimers with encapsulated tiny platinum nanoparticles. We systematically conducted the synthesis and characterization of the dendrimer-encapsulated Pt nanoparticles (denoted Pt-dendrimer) and confirmed their enzymatic function (hydrogen peroxide (H2O2) decomposition) within various cell lines (normal, cancerous), including glioblastoma (GBM) cells. By understanding the effects of the Pt-dendrimer at the gene level, especially related to cancer cell metastasis, we have thoroughly demonstrated its ability for tumor alleviation and suppressing GBM migration, invasion, and adhesion. The present findings show great promise for the application of the nanozyme for use in GBM-related basic research as well as at clinical sites.

Human astrocytes and astrocytoma respond differently to resveratrol

A fundamental problem in oncology is that anticancer chemotherapeutics kill both cancer and healthy cells in the surrounding tissues. Resveratrol is a natural antioxidant with intriguing and opposing biological properties: it reduces viability of some cancer cells but not of non-transformed ones (in equimolar concentrations). Therefore, we examined resveratrol in human non-transformed primary astrocytes and astrocytoma. Resveratrol reduced reactive oxygen species in astrocytes, but not in astrocytoma. Such cell-type dependent response is particularly evident with analyses at the single cell level showing clear population difference in high and low glutathione levels. Due to resveratrol's poor aqueous solubility that limits its use in clinics, we incorporated it into stimulus-responsive micelles assembled from miktoarm polymers. This could be an attractive chemotherapeutic delivery strategy in nano-oncology. As a proof of principle, we show that these formulations containing resveratrol markedly decrease astrocytoma viability, particularly in combination with temozolomide, a first line chemotherapeutic for astrocytoma.

Lipid peroxidation in brain tumors

There is a lot of evidence showing that lipid peroxidation plays very important role in development of various diseases, including neurodegenerative diseases and brain tumors. Lipid peroxidation is achieved by two main pathways, by enzymatic or by non-enzymatic oxidation, respectively. In this paper, we focus on non-enzymatic, self-catalyzed chain reaction of poly-unsaturated fatty acid (PUFA) peroxidation generating reactive aldehydes, notably 4-hydroxynonenal (4-HNE), which acts as second messenger of free radicals and as growth regulating factor. It might originate from astrocytes as well as from blood vessels, even within the blood-brain barrier (BBB), which is in case of brain tumors transformed into the blood-brain-tumor barrier (BBTB). The functionality of the BBB is strongly affected by 4-HNE because it forms relatively stable protein adducts thus allowing the persistence and the spread of lipid peroxidation, as revealed by immunohistochemical findings. Because 4-HNE can act as a regulator of vital functions of normal and of malignant cells acting in the cell type- and concentration-dependent manners, the bioactivities of this product of lipid peroxidation be should further studied to reveal if it acts as a co-factor of carcinogenesis or as natural factor of defense against primary brain tumors and metastatic cancer.

Implications of Oxidative Stress in Glioblastoma Multiforme Following Treatment with Purine Derivatives

Recently, small compound-based therapies have provided new insights into the treatment of glioblastoma multiforme (GBM) by inducing oxidative impairment. Kinetin riboside (KR) and newly designed derivatives (8-azaKR, 7-deazaKR) selectively affect the molecular pathways crucial for cell growth by interfering with the redox status of cancer cells. Thus, these compounds might serve as potential alternatives in the oxidative therapy of GBM. The increased basal levels of reactive oxygen species (ROS) in GBM support the survival of cancer cells and cause drug resistance. The simplest approach to induce cell death is to achieve the redox threshold and circumvent the antioxidant defense mechanisms. Consequently, cells become more sensitive to oxidative stress (OS) caused by exogenous agents. Here, we investigated the effect of KR and its derivatives on the redox status of T98G cells in 2D and 3D cell culture. The use of spheroids of T98G cells enabled the selection of one derivative-7-deazaKR-with comparable antitumor activity to KR. Both compounds induced ROS generation and genotoxic OS, resulting in lipid peroxidation and leading to apoptosis. Taken together, these results demonstrated that KR and 7-deazaKR modulate the cellular redox environment of T98G cells, and vulnerability of these cells is dependent on their antioxidant capacity.

Current Perspective on the Natural Compounds and Drug Delivery Techniques in Glioblastoma Multiforme

Simple Summary

Glioblastoma multiforme (GBM) is one of the belligerent neoplasia that metastasize to other brain regions and invade nearby healthy tissues. However, the treatments available are associated with some limitations, such as high variations in solid tumors and deregulation of multiple cellular pathways. The heterogeneity of the GBM tumor and its aggressive infiltration into the nearby tissues makes it difficult to treat. Hence, the development of multimodality therapy that can be more effective, novel, with fewer side effects, improving the prognosis for GBM is highly desired. This review evaluated the use of natural phytoconstituents as an alternative for the development of a new therapeutic strategy. The key aspects of GBM and the potential of drug delivery techniques were also assessed, for tumor site delivery with limited side-effects. These efforts will help to provide better therapeutic options to combat GBM in future.

Abstract

Glioblastoma multiforme (GBM) is one of the debilitating brain tumors, being associated with extremely poor prognosis and short median patient survival. GBM is associated with complex pathogenesis with alterations in various cellular signaling events, that participate in cell proliferation and survival. The impairment in cellular redox pathways leads to tumorigenesis. The current standard pharmacological regimen available for glioblastomas, such as radiotherapy and surgical resection following treatment with chemotherapeutic drug temozolomide, remains fatal, due to drug resistance, metastasis and tumor recurrence. Thus, the demand for an effective therapeutic strategy for GBM remains elusive. Hopefully, novel products from natural compounds are suggested as possible solutions. They protect glial cells by reducing oxidative stress and neuroinflammation, inhibiting proliferation, inducing apoptosis, inhibiting pro-oncogene events and intensifying the potent anti-tumor therapies. Targeting aberrant cellular pathways in the amelioration of GBM could promote the development of new therapeutic options that improve patient quality of life and extend survival. Consequently, our review emphasizes several natural compounds in GBM treatment. We also assessed the potential of drug delivery techniques such as nanoparticles, Gliadel wafers and drug delivery using cellular carriers which could lead to a novel path for the obliteration of GBM.

Targeting Neuroinflammation in Brain Cancer: Uncovering Mechanisms, Pharmacological Targets, and Neuropharmaceutical Developments

Gliomas are one of the most lethal types of cancers accounting for ∼80% of all central nervous system (CNS) primary malignancies. Among gliomas, glioblastomas (GBM) are the most aggressive, characterized by a median patient survival of fewer than 15  months. Recent molecular characterization studies uncovered the genetic signatures and methylation status of gliomas and correlate these with clinical prognosis. The most relevant molecular characteristics for the new glioma classification are IDH mutation, chromosome 1p/19q deletion, histone mutations, and other genetic parameters such as ATRX loss, TP53, and TERT mutations, as well as DNA methylation levels. Similar to other solid tumors, glioma progression is impacted by the complex interactions between the tumor cells and immune cells within the tumor microenvironment. The immune system’s response to cancer can impact the glioma’s survival, proliferation, and invasiveness. Salient characteristics of gliomas include enhanced vascularization, stimulation of a hypoxic tumor microenvironment, increased oxidative stress, and an immune suppressive milieu. These processes promote the neuro-inflammatory tumor microenvironment which can lead to the loss of blood-brain barrier (BBB) integrity. The consequences of a compromised BBB are deleteriously exposing the brain to potentially harmful concentrations of substances from the peripheral circulation, adversely affecting neuronal signaling, and abnormal immune cell infiltration; all of which can lead to disruption of brain homeostasis. In this review, we first describe the unique features of inflammation in CNS tumors. We then discuss the mechanisms of tumor-initiating neuro-inflammatory microenvironment and its impact on tumor invasion and progression. Finally, we also discuss potential pharmacological interventions that can be used to target neuro-inflammation in gliomas.

Insight into the potential application of polyphenol-rich dietary intervention in degenerative disease management

In recent times, a great number of plants have been studied in order to identify new components with nutraceutical properties, among which are polyphenols. Dietary polyphenols represent a large group of bioactive molecules widely found in the food of plant origin and they have been found able to prevent the onset and progression of degenerative diseases, and to reduce and control their symptoms. These health protective effects have been mainly related to their antioxidant and anti-inflammatory properties. However, it must be considered that the application of isolated polyphenols as nutraceuticals is quite limited due to their poor systemic distribution and relative bioavailability. The present review highlights the potential effect of dietary intervention with polyphenol-rich food and plant extracts in patients with cancer, diabetes and neurodegenerative, autoimmune, cardiovascular and ophthalmic diseases, as well as the possible molecular mechanisms of action suggested in numerous studies with animal models.

Concanavalin A induces apoptosis in a dose-dependent manner by modulating thiol/disulfide homeostasis in C6 glioblastoma cells

Glioma is the most common brain tumor. C6 rat glioblastoma cells provide the possibility to the scientist to study brain cancer. Concanavalin A (Con A) has a lot of antitumoral effects, especially over oxidative stress. In the present study, it was aimed to decide the impacts of various doses of Con A on C6 glioblastoma cells regarding cytotoxicity, thiol/disulfide homeostasis, apoptosis, and inflammation. We detected the cytotoxic activity of Con A (from 7.8 to 500 µg/ml) in C6 cells by utilizing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and determined the toxic concentration of Con A. Once the optimal doses were found, the thiol-disulfide homeostasis, levels of total antioxidant and oxidant status (TAS and TOS), malondialdehyde (MDA) and glutathione (GSH), pro-inflammatory cytokines as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), apoptotic proteins as cytochrome c (CYCS), and caspase 3 (CASP3) were measured. Apoptotic and morphological changes in the C6 cells were examined with an inverted microscope and flow cytometry technique. Dose-dependent Con A triggered oxidative damage in the C6 cells, affecting the inflammatory pathway, so reducing proliferation with apoptotic proteins and morphological changes. But especially, Con A increased disulfide formation by disrupting the thiol/disulfide balance in C6 cells. This study revealed that Con A, known as carbohydrate-binding protein, generated oxidative damage, inflammation, and apoptosis in a dose-dependent manner by modulating thiol/disulfide homeostasis in C6 glioblastoma cells.

Targeting BMI-1 with PLGA–PEG nanoparticle-containing PTC209 modulates the behavior of human glioblastoma stem cells and cancer cells

Despite advances in glioblastoma (GBM) treatments, current approaches have failed to improve the overall survival of patients. The oncogene BMI-1, a core member of the polycomb group proteins, is a potential novel therapeutic target for GBM. To enhance the efficacy and reduce the toxicity, PTC209, a BMI-1 inhibitor, was loaded into a PLGA–PEG nanoparticle conjugated with CD133 antibody (Nano-PTC209) and its effect on the behavior of human GBM stem-like cells (GSCs) and the human glioblastoma cell line (U87MG) was assessed. Nano-PTC209 has a diameter of ~ 75 nm with efficient drug loading and controlled release. The IC50 values of Nano-PTC209 for GSCs and U87MG cells were considerably lower than PTC209. Nano-PTC209 significantly decreased the viability of both GSCs and U87MG cells in a dose-dependent manner and caused a significant enhancement of apoptosis and p53 levels as well as inhibition of AKT and JNK signaling pathways. Furthermore, Nano-PTC209 significantly inhibited the migration ability, decreased the activity of metalloproteinase-2 and -9, and increased the generation of reactive oxygen species in both GSCs and U87MG cells. Our data indicate that PLGA–PEG nanoparticle conjugated with CD133 antibody could be an ideal nanocarrier to deliver PTC209 and effectively target BMI-1 for potential approaches in the treatment of GBM.

PAM (PIK3/AKT/mTOR) signaling in glia: potential contributions to brain tumors in aging

Despite a growing proportion of aged individuals at risk for developing cancer in the brain, the prognosis for these conditions remains abnormally poor due to limited knowledge of underlying mechanisms and minimal treatment options. While cancer metabolism in other organs is commonly associated with upregulated glycolysis (i.e. Warburg effect) and hyperactivation of PIK3/AKT/mTOR (PAM) pathways, the unique bioenergetic demands of the central nervous system may interact with these oncogenic processes to promote tumor progression in aging. Specifically, constitutive glycolysis and PIK3/AKT/mTOR signaling in glia may be dysregulated by age-dependent alterations in neurometabolic demands, ultimately contributing to pathological processes otherwise associated with PIK3/AKT/mTOR induction (e.g. cell cycle entry, impaired autophagy, dysregulated inflammation). Although several limitations to this theoretical model exist, the consideration of aberrant PIK3/AKT/mTOR signaling in glia during aging elucidates several therapeutic opportunities for brain tumors, including non-pharmacological interventions.

Understanding the glioblastoma tumor biology to optimize photodynamic therapy: From molecular to cellular events

Photodynamic therapy (PDT) has recently gained attention as an alternative treatment of malignant gliomas. Glioblastoma (GBM) is the most prevalent within tumors of the central nervous system (CNS). Conventional treatments for this CNS tumor include surgery, radiation, and chemotherapy. Surgery is still being considered as the treatment of choice. Even so, the poor prognosis and/or recurrence of the disease after applying any of these treatments highlight the urgency of exploring new therapies and/or improving existing ones to achieve the definitive eradication of tumor masses and remaining cells. PDT is a therapeutic modality that involves the destruction of tumor cells by reactive oxygen species induced by light, which were previously treated with a photosensitizing agent. However, in recent years, its experimental application has expanded to other effects that could improve overall performance against GBM. In the current review, we revisit the main advances of PDT for GBM management and also, the recent mechanistic insights about cellular and molecular aspects related to tumoral resistance to PDT of GBM.

Amalgamation of PI3K and EZH2 blockade synergistically regulates invasion and angiogenesis: combination therapy for glioblastoma multiforme

Glioblastoma multiforme is known as the primary malignant and most devastating form of tumor in central nervous system of adult population. Amongst all CNS cancers, Glioblastoma multiforme GBM is a rare grade IV astrocytoma and it has the worst prognosis initiated by metastasis to supra-tentorial region of the brain. Current options for the treatment include surgery, radiation therapy and chemotherapy. Substantial information of its pathology and molecular signaling exposed new avenues for generating innovative therapies. In our study, we have undertaken a novel combination approach for GBM treatment. PI3K signaling participates in cancer progression and plays a significant role in metastasis. Here, we are targeting PI3K signaling pathways in glioblastoma along with EZH2, a known transcriptional regulator. We found that targeting transcriptional regulator EZH2 and PI3K affect cellular migration and morphological changes. These changes in signatory activities of cancerous cells led to inhibit its progression in vitro. With further analysis we confirmed the angiogenic inhibition and reduction in stem-ness potential of GBM. Later, cytokine proteome array analysis revealed several participants of metastasis and tumor induced angiogenesis using combination regime. This study provides a significant reduction in GBM progression investigated using Glioblastoma Multiforme U-87 cells with effective combination of pharmacological inhibitors PI-103 and EPZ-6438. This strategy will be further used to combat GBM more innovatively along with the existing therapies.

Gold nanoparticles carrying or not anti-VEGF antibody do not change glioblastoma multiforme tumor progression in mice

Aims

Glioblastoma multiforme (GBM) is the most devastating malignant primary brain tumor known. Life expectance is around 15 months after diagnosis. Several events contribute to the GBM progression such as uncontrolled genetic cancer cells proliferation, angiogenesis (mostly vascular endothelial growth factor (VEGF)-mediated), tissue invasion, glioma stem cell activity, immune system failure, and a hypoxic and inflammatory tumor microenvironment. Tumor cells antiproliferative effect of 20 nm citrate-covered gold nanoparticles (cit-AuNP) has been reported, along with anti-inflammatory and anti-oxidative effects. We aimed to test whether either chronic treatment with 20 nm cit-AuNP or anti-VEGF antibody (Ig)-covered AuNP could reduce GBM progression in mice.

Main methods

Effect of the gold nanoparticles on the GL261 glioblastoma cells proliferation in vitro, and on the GL261-induced glioblastoma cell growth in C57BL/6 mice in vivo were tested. Besides, fluorophore-conjugated gold nanoparticles penetration through the GL261 plasma cell membrane, gold labelling in brain parenchyma of glioblastoma-carrying mice, and VEGF expression into the tumor were evaluated.

Key findings

We observed cit-AuNP did no change the GL261 cells proliferation. Similarly, we demonstrated chronic treatment with either cit-AuNP or anti-VEGF Ig-covered AuNP did not modify the GL261 cells-induced GBM progression in mice. By the end, we showed AuNPs did not trespass in appreciable amount both the GL261 plasma cell membrane and the tumoral blood brain barrier (BBB), and did not change the VEGF expression into the tumor.

Significance

20 nm cit-AuNP or anti-VEGF Ig covered-AuNP are not good tools to reduce GBM in mice, probably because they do not penetrate both tumor cells and BBB in enough amount to reduce tumor growing.

Redox Regulator GLRX Is Associated With Tumor Immunity in Glioma

Glutaredoxin is central to cellular redox chemistry and regulates redox homeostasis and malignant progression of many cancers. In glioma, the role of its coding gene (GLRX) remains unclear. We aimed to elucidate the role of glutaredoxin at the transcriptome level and its clinical prognostic value in glioma. In total, we evaluated 1,717 glioma samples with transcriptome data and corresponding clinical data as well as single-cell sequencing data from 6 glioma patients from publicly available databases. Gene set variation analysis and gene ontology analysis were performed to reveal the biological function of GLRX. The immune cell enrichment score was calculated by GSVA analysis. Single-cell sequencing data was visualized by t-distributed stochastic neighbor embedding analysis. The prognostic value of GLRX in glioma was verified by the Kaplan-Meier curve and multivariate COX analysis. GLRX was found to be highly enriched in gliomas of higher grades with wild-type IDH, without 1p/19q co-deletion, and with a methylated MGMT promoter. Moreover, GLRX could be a potential marker for the mesenchymal molecular subtype of gliomas. The expression of GLRX was closely related to the tumor immune process, immune checkpoints, and inflammatory factors with GLRX being specifically expressed in M0 macrophages. GLRX is also shown to be an independent prognostic factor in glioma. Altogether, our study outcomes show that GLRX is highly enriched in malignant gliomas and is closely related to the tumor immune microenvironment. Therefore, GLRX-targeted cell redox regulatory therapy may enhance the efficacy of glioma immunotherapy.