Therapeutic Potential of Autophagy in Glioblastoma Treatment With Phosphoinositide 3-Kinase/Protein Kinase B/Mammalian Target of Rapamycin Signaling Pathway Inhibitors

Rejuvenating Aged Bone Repair through Multihierarchy Reactive Oxygen Species-Regulated Hydrogel

Aging exacerbates the dysfunction of tissue regeneration at multiple levels and gradually diminishes individual's capacity to withstand stress, damage, and disease. The excessive accumulation of reactive oxygen species (ROS) is considered a hallmark feature of senescent stem cells, which causes oxidative stress, deteriorates the host microenvironment, and eventually becomes a critical obstacle for aged bone defect repair. Till now, the strategies cannot synchronously and thoroughly regulate intracellular and extracellular ROS in senescent cells. Herein, a multihierarchy ROS scavenging system for aged bone regeneration is developed by fabricating an injectable PEGylated poly(glycerol sebacate) (PEGS-NH2 )/poly(γ-glutamic acid) (γ-PGA) hydrogel containing rapamycin-loaded poly(diselenide-carbonate) nanomicelles (PSeR). This PSeR hydrogel exhibits highly sensitive ROS responsiveness to the local aged microenvironment and dynamically releases drug-loaded nanomicelles to scavenge the intracellular ROS accumulated in senescent bone mesenchymal stem cells. The PSeR hydrogel effectively tunes the antioxidant function and delays senescence of bone mesenchymal stem cells by safeguarding DNA replication in an oxidative environment, thereby promoting the self-renewal ability and enhancing the osteogenic capacity for aged bone repair in vitro and in vivo. Thus, this multihierarchy ROS-regulated hydrogel provides a new strategy for treating degenerative diseases.

Glioblastoma Therapy: Past, Present and Future

Glioblastoma (GB) stands out as the most prevalent and lethal form of brain cancer. Although great efforts have been made by clinicians and researchers, no significant improvement in survival has been achieved since the Stupp protocol became the standard of care (SOC) in 2005. Despite multimodality treatments, recurrence is almost universal with survival rates under 2 years after diagnosis. Here, we discuss the recent progress in our understanding of GB pathophysiology, in particular, the importance of glioma stem cells (GSCs), the tumor microenvironment conditions, and epigenetic mechanisms involved in GB growth, aggressiveness and recurrence. The discussion on therapeutic strategies first covers the SOC treatment and targeted therapies that have been shown to interfere with different signaling pathways (pRB/CDK4/RB1/P16ink4, TP53/MDM2/P14arf, PI3k/Akt-PTEN, RAS/RAF/MEK, PARP) involved in GB tumorigenesis, pathophysiology, and treatment resistance acquisition. Below, we analyze several immunotherapeutic approaches (i.e., checkpoint inhibitors, vaccines, CAR-modified NK or T cells, oncolytic virotherapy) that have been used in an attempt to enhance the immune response against GB, and thereby avoid recidivism or increase survival of GB patients. Finally, we present treatment attempts made using nanotherapies (nanometric structures having active anti-GB agents such as antibodies, chemotherapeutic/anti-angiogenic drugs or sensitizers, radionuclides, and molecules that target GB cellular receptors or open the blood-brain barrier) and non-ionizing energies (laser interstitial thermal therapy, high/low intensity focused ultrasounds, photodynamic/sonodynamic therapies and electroporation). The aim of this review is to discuss the advances and limitations of the current therapies and to present novel approaches that are under development or following clinical trials.

Progress in Glioma Stem Cell Research

Glioblastoma multiforme (GBM) represents a diverse spectrum of primary tumors notorious for their resistance to established therapeutic modalities. Despite aggressive interventions like surgery, radiation, and chemotherapy, these tumors, due to factors such as the blood-brain barrier, tumor heterogeneity, glioma stem cells (GSCs), drug efflux pumps, and DNA damage repair mechanisms, persist beyond complete isolation, resulting in dismal outcomes for glioma patients. Presently, the standard initial approach comprises surgical excision followed by concurrent chemotherapy, where temozolomide (TMZ) serves as the foremost option in managing GBM patients. Subsequent adjuvant chemotherapy follows this regimen. Emerging therapeutic approaches encompass immunotherapy, including checkpoint inhibitors, and targeted treatments, such as bevacizumab, aiming to exploit vulnerabilities within GBM cells. Nevertheless, there exists a pressing imperative to devise innovative strategies for both diagnosing and treating GBM. This review emphasizes the current knowledge of GSC biology, molecular mechanisms, and associations with various signals and/or pathways, such as the epidermal growth factor receptor, PI3K/AKT/mTOR, HGFR/c-MET, NF-κB, Wnt, Notch, and STAT3 pathways. Metabolic reprogramming in GSCs has also been reported with the prominent activation of the glycolytic pathway, comprising aldehyde dehydrogenase family genes. We also discuss potential therapeutic approaches to GSC targets and currently used inhibitors, as well as their mode of action on GSC targets.

Autophagy Modulation and Its Implications on Glioblastoma Treatment

Autophagy is a vital cellular process that functions to degrade and recycle damaged organelles into basic metabolites. This allows a cell to adapt to a diverse range of challenging conditions. Autophagy assists in maintaining homeostasis, and it is tightly regulated by the cell. The disruption of autophagy has been associated with many diseases, such as neurodegenerative disorders and cancer. This review will center its discussion on providing an in-depth analysis of the current molecular understanding of autophagy and its relevance to brain tumors. We will delve into the current literature regarding the role of autophagy in glioma pathogenesis by exploring the major pathways of JAK2/STAT3 and PI3K/AKT/mTOR and summarizing the current therapeutic interventions and strategies for glioma treatment. These treatments will be evaluated on their potential for autophagy induction and the challenges associated with their utilization. By understanding the mechanism of autophagy, clinical applications for future therapeutics in treating gliomas can be better targeted.

Unveiling Novel Avenues in mTOR-Targeted Therapeutics: Advancements in Glioblastoma Treatment

The mTOR signaling pathway plays a pivotal and intricate role in the pathogenesis of glioblastoma, driving tumorigenesis and proliferation. Mutations or deletions in the PTEN gene constitutively activate the mTOR pathway by expressing growth factors EGF and PDGF, which activate their respective receptor pathways (e.g., EGFR and PDGFR). The convergence of signaling pathways, such as the PI3K-AKT pathway, intensifies the effect of mTOR activity. The inhibition of mTOR has the potential to disrupt diverse oncogenic processes and improve patient outcomes. However, the complexity of the mTOR signaling, off-target effects, cytotoxicity, suboptimal pharmacokinetics, and drug resistance of the mTOR inhibitors pose ongoing challenges in effectively targeting glioblastoma. Identifying innovative treatment strategies to address these challenges is vital for advancing the field of glioblastoma therapeutics. This review discusses the potential targets of mTOR signaling and the strategies of target-specific mTOR inhibitor development, optimized drug delivery system, and the implementation of personalized treatment approaches to mitigate the complications of mTOR inhibitors. The exploration of precise mTOR-targeted therapies ultimately offers elevated therapeutic outcomes and the development of more effective strategies to combat the deadliest form of adult brain cancer and transform the landscape of glioblastoma therapy.

A combination of metformin and epigallocatechin gallate potentiates glioma chemotherapy in vivo

Glioma is the most devastating high-grade tumor of the central nervous system, with dismal prognosis. Existing treatment modality does not provide substantial benefit to patients and demands novel strategies. One of the first-line treatments for glioma, temozolomide, provides marginal benefit to glioma patients. Repurposing of existing non-cancer drugs to treat oncology patients is gaining momentum in recent years. In this study, we investigated the therapeutic benefits of combining three repurposed drugs, namely, metformin (anti-diabetic) and epigallocatechin gallate (green tea-derived antioxidant) together with temozolomide in a glioma-induced xenograft rat model. Our triple-drug combination therapy significantly inhibited tumor growth in vivo and increased the survival rate (50%) of rats when compared with individual or dual treatments. Molecular and cellular analyses revealed that our triple-drug cocktail treatment inhibited glioma tumor growth in rat model through ROS-mediated inactivation of PI3K/AKT/mTOR pathway, arrest of the cell cycle at G1 phase and induction of molecular mechanisms of caspases-dependent apoptosis.In addition, the docking analysis and quantum mechanics studies performed here hypothesize that the effect of triple-drug combination could have been attributed by their difference in molecular interactions, that maybe due to varying electrostatic potential. Thus, repurposing metformin and epigallocatechin gallate and concurrent administration with temozolomide would serve as a prospective therapy in glioma patients.

PCLassoLog: A protein complex-based, group Lasso-logistic model for cancer classification and risk protein complex discovery

Risk gene identification has attracted much attention in the past two decades. Since most genes need to be translated into proteins and cooperate with other proteins to form protein complexes to carry out cellular functions, which significantly extends the functional diversity of individual proteins, revealing the molecular mechanism of cancer from a comprehensive perspective needs to shift from identifying individual risk genes toward identifying risk protein complexes. Here, we embed protein complexes into the regularized learning framework and propose a protein complex-based, group Lasso-logistic model (PCLassoLog) to discover risk protein complexes. Experiments on deep proteomic data of two cancer types show that PCLassoLog yields superior predictive performance on independent datasets. More importantly, PCLassoLog identifies risk protein complexes that not only contain individual risk proteins but also incorporate close partners that synergize with them. Furthermore, selection probabilities are calculated and two other protein complex-based models are proposed to complement PCLassoLog in identifying reliable risk protein complexes. Based on PCLassoLog, a pan-cancer analysis is performed to identify risk protein complexes in 12 cancer types. Finally, PCLassoLog is used to discover risk protein complexes associated with gene mutation. We implement all protein complex-based models as an R package PCLassoReg, which may serve as an effective tool to discover risk protein complexes in various contexts.

Theabrownins Produced via Chemical Oxidation of Tea Polyphenols Inhibit Human Lung Cancer Cells in vivo and in vitro by Suppressing the PI3K/AKT/mTOR Pathway Activation and Promoting Autophagy

During the fermentation of dark tea, theabrownins (TBs), carbohydrates, and other substances get irreversibly complex. Recent research on the biological activity of TBs is not based on free TBs. In the present study, some brown polyphenol oxidized polymers, the generalized TBs (TBs-C), were prepared via alkali oxidation from tea polyphenols (TP). We also investigated the inhibitory mechanism of TBs-C on non-small-cell-lung cancer (NSCLC). TBs-C demonstrated a stronger inhibition than TP on the NSCLC cell lines A549, H2030, HCC827, H1975, and PC9. Next, A549 and H2030 cell lines were selected as subjects to explore this mechanism. TBs-C was found to inhibit proliferation, promote apoptosis, and induce G1 cell-cycle arrest in the cells. In addition, TBs-C increased autophagic flux, which in turn promoted the death of lung cancer cells. Moreover, TBs-C suppressed the PI3K/AKT/mTOR pathway activation, promoted autophagy, and increased the expression of p21 downstream of AKT, which resulted in G1 cell-cycle arrest. In xenotransplanted NSCLC nude mice derived from A549 cells, TBs-C could significantly suppress tumor growth by inhibiting the PI3K/AKT/mTOR pathway without causing hepatotoxicity, brain toxicity, or nephrotoxicity. We believe that our present findings would facilitate advancement in the research and industrialization of TBs.

Recent Advances in Ovarian Cancer: Therapeutic Strategies, Potential Biomarkers, and Technological Improvements

Aggressive and recurrent gynecological cancers are associated with worse prognosis and a lack of effective therapeutic response. Ovarian cancer (OC) patients are often diagnosed in advanced stages, when drug resistance, angiogenesis, relapse, and metastasis impact survival outcomes. Currently, surgical debulking, radiotherapy, and/or chemotherapy remain the mainstream treatment modalities; however, patients suffer unwanted side effects and drug resistance in the absence of targeted therapies. Hence, it is urgent to decipher the complex disease biology and identify potential biomarkers, which could greatly contribute to making an early diagnosis or predicting the response to specific therapies. This review aims to critically discuss the current therapeutic strategies for OC, novel drug-delivery systems, and potential biomarkers in the context of genetics and molecular research. It emphasizes how the understanding of disease biology is related to the advancement of technology, enabling the exploration of novel biomarkers that may be able to provide more accurate diagnosis and prognosis, which would effectively translate into targeted therapies, ultimately improving patients’ overall survival and quality of life.

N6-Methyladenosine Methyltransferase METTL14-Mediated Autophagy in Malignant Development of Oral Squamous Cell Carcinoma

N6-methyladenosine (m⁶A) is the most abundant internal mRNA modification in eukaryotes and is related to stability, localization, or translation efficiency in tumorigenesis. Autophagy plays an important role in the occurrence and development of tumours. However, the relationship between m⁶A and autophagy remains unclear. In this study, we used a rapamycin-induced autophagy model of oral squamous cell carcinoma (OSCC) cells, and observed increased m⁶A RNA methylation. When autophagy was activated, the methyltransferase-like 14 (METTL14) expression was upregulated and influenced the proliferation, migration, and invasiveness of OSCC cells. Through meRIP-seq and RNA-seq analysis, we found that METTL14 directly combined with eukaryotic translation initiation factor gamma 1 (eIF4G1) mRNA and decreased its RNA stability. According to the dual-luciferase reporter and mutagenesis assay, the mutated site 1 of exon 11 of eIF4G1 is the key target of METTL14. Knockdown of the main m⁶A binding protein YTHDF2 may rescue the shortened half-life of eIF4G1 mRNA induced by METTL14 overexpression. Furthermore, an in vivo tumour xenograft model confirmed that a high METTL14 expression can effectively reduce OSCC growth. Additionally, using clinical samples, we found that patients with advanced or moderately/poorly differentiated tumours exhibited lower METTL14 levels. Taken together, our results revealed that METTL14 mediated eIF4G1 expression via m⁶A modification and regulated autophagy levels and biological functions in OSCC. Our findings not only expand our understanding of the correlation between autophagy and RNA methylation in tumorigenesis but also present an opportunity to develop new therapeutic options.

Gymnema sylvestre Extract Restores the Autophagic Pathway in Human Glioblastoma Cells U87Mg

Simple Summary

The treatment of GBM is extremely difficult and complicated by the heterogeneous nature of neoplastic cells. The problems inherent in treating any central nervous system tumour are due to the anatomical complexity and the limited repair mechanisms of the surrounding unaffected tissues. The choice of the most suitable treatment for GBM depends on several factors: the location of the disease, the extent, and the nature of the tumour. The limit of this choice is mainly due to the degree of complexity of the disease and to the mechanisms of drug resistance that the neoplasm develops during the treatment. Herbal medicines and their derived phytocompounds are increasingly recognised as useful complementary treatments for cancer. Numerous clinical studies have reported the beneficial effects of herbal medicines on survival, immune modulation, and quality of life of cancer patients when used in combination with conventional therapies. In this study, we investigated all the mechanisms that control tumour cell growth after induction with Gymnema sylvestre (GS) extract and the key proteins that regulate these mechanisms in glioblastoma cells. The study is of great translational interest because the natural substances used could be proposed as natural adjuvant drugs for the treatment of glioblastoma, and therefore could act by modulating new molecular targets for the control of brain tumour cell growth.

Abstract

Glioblastoma is a brain tumour, characterised by recurrent or innate resistance to conventional chemoradiotherapy. Novel natural molecules and phyto-extracts have been proposed as adjuvants to sensitise the response to Temozolomide (TMZ). In this study, we investigated the effect of GS extract on human glioblastoma cells U87Mg. According to the IC50-values, GS extract displayed a significant cytotoxicity. This was confirmed by cell growth inhibition and alteration in metabolic activity evaluated by cell count and MTT assay. GS induced reduction in Pro-caspase 9, 3, but not PARP cleavage nor DNA fragmentation. Thus, in GS-induced cytotoxicity, cell death is not associated with apoptosis. In this context, short-term treatment of U87Mg cells with GS extract (1 mg/mL) reduced the phosphorylation levels of mTOR and of its downstream target P70 S6 kinase, highlighting the role of GS extract into autophagy induction. The activation of autophagic flux by GS extract was confirmed by Western blot analysis, which revealed the reduction in p62 and the concomitant increase in LC3B II/I ratio. Immunofluorescence evidenced the accumulation of LC3B puncta in U87Mg cells pretreated with autophagy inhibitor Bafilomycin A1. Furthermore, as main key regulators of type II programmed cell death, p53, p21 and CDK4 were also investigated and were inhibited by GS treatment. In conclusion, GS extract could be considered as an autophagy inducer in glioblastoma cells U87Mg.

Advances in autophagy as a target in the treatment of tumours

Autophagy is a multi-step lysosomal degradation process, which regulates energy and material metabolism and has been used to maintain homeostasis. Autophagy has been shown to be involved in the regulation of health and disease. But at present, there is no consensus on the relationship between autophagy and tumour, and we consider that it plays a dual role in the occurrence and development of tumour. That is to say, under certain conditions, it can inhibit the occurrence of tumour, but it can also promote the process of tumour. Therefore, autophagy could be used as a target for tumour treatment. The regulation of autophagy plays a synergistic role in the radiotherapy, chemotherapy, phototherapy and immunotherapy of tumour, and nano drug delivery system provides a promising strategy for improving the efficacy of autophagy regulation. This review summarised the progress in the regulatory pathways and factors of autophagy as well as nanoformulations as carriers for the delivery of autophagy modulators.

Enhancement of Biological and Pharmacological Properties of an Encapsulated Polyphenol: Curcumin

There is a dearth of natural remedies available for the treatment of an increasing number of diseases facing mankind. Natural products may provide an opportunity to produce formulations and therapeutic solutions to address this shortage. Curcumin (CUR), diferuloylmethane; I,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione is the major pigment in turmeric powder which has been reported to exhibit a number of health benefits including, antibacterial, antiviral, anti-cancer, anti-inflammatory and anti-oxidant properties. In this review, the authors attempt to highlight the biological and pharmacological properties of CUR in addition to emphasizing aspects relating to the biosynthesis, encapsulation and therapeutic effects of the compound. The information contained in this review was generated by considering published information in which evidence of enhanced biological and pharmacological properties of nano-encapsulated CUR was reported. CUR has contributed to a significant improvement in melanoma, breast, lung, gastro-intestinal, and genito-urinary cancer therapy. We highlight the impact of nano-encapsulated CUR for efficient inhibition of cell proliferation, even at low concentrations compared to the free CUR when considering anti-proliferation. Furthermore nano-encapsulated CUR exhibited bioactive properties, exerted cytotoxic and anti-oxidant effects by acting on endogenous and cholinergic anti-oxidant systems. CUR was reported to block Hepatitis C virus (HCV) entry into hepatic cells, inhibit MRSA proliferation, enhance wound healing and reduce bacterial load. Nano-encapsulated CUR has also shown bioactive properties when acting on antioxidant systems (endogenous and cholinergic). Future research is necessary and must focus on investigation of encapsulated CUR nano-particles in different models of human pathology.

N6-methyladenosine demethyltransferase FTO-mediated autophagy in malignant development of oral squamous cell carcinoma

N6-methyladenosine (m⁶A) is the most abundant internal mRNA modification in eukaryotes and plays an important role in tumorigenesis. However, the underlying mechanism remains largely unclear. Here, we established a cell model of rapamycin-induced autophagy to screen m⁶A-modifying enzymes. We found that m⁶A demethylase fat mass and obesity-associated protein (FTO) plays a key role in regulating autophagy and tumorigenesis by targeting the gene encoding eukaryotic translation initiation factor gamma 1 (eIF4G1) in oral squamous cell carcinoma (OSCC). Knocked down of FTO expression in OSCC cell lines, resulting in downregulation of eIF4G1 along with enhanced autophagic flux and inhibition of tumorigenesis. Rapamycin inhibited FTO activity, and directly targeted eIF4G1 transcripts and mediated their expression in an m⁶A-dependent manner. Dual-luciferase reporter and mutagenesis assays confirmed that YTH N6-methyladenosine RNA-binding protein 2 (YTHDF2) targets eIF4G1. Conclusively, after FTO silencing, YTHDF2 captured eIF4G1 transcripts containing m⁶A, resulting in mRNA degradation and decreased expression of eIF4G1 protein, thereby promoting autophagy and reducing tumor occurrence. Therefore, rapamycin may regulate m⁶A levels, determining the autophagic flux of OSCC, thereby affecting the biological characteristics of cancer cells. This insight expands our understanding of the crosstalk between autophagy and RNA methylation in tumorigenesis, which is essential for therapeutic strategy development for OSCC.

Pemafibrate Pretreatment Attenuates Apoptosis and Autophagy during Hepatic Ischemia-Reperfusion Injury by Modulating JAK2/STAT3β/PPARα Pathway

Hepatic ischemia-reperfusion injury (HIRI) is a common phenomenon in liver transplantation and liver surgery. This article is aimed at clarifying the role of pemafibrate in HIRI through JAK2/STAT3β/PPARα. In the experiment, we divided Balb/c into seven groups, namely, normal control (NC), Sham, PEM (1.0 mg/kg), IRI, IRI + PEM (0.1 mg/kg), IRI + PEM (0.5 mg/kg), and IRI + PEM (1.0 mg/kg). We used biochemical assay, histopathological evaluation, immunohistochemistry, RT-PCR and qRT-PCR, ELISA analysis, and other methods to determine the level of serum AST, ALT, IL-1β, and TNF-α in the liver at three time points (2 h, 8 h, and 24 h) after reperfusion of apoptosis factor, autophagy factor, and the JAK2/STAT3/PPARα content in tissues. Our experiment results showed that the pemafibrate can effectively reduce the level of hepatic IR injury. In addition, pemafibrate has anti-inflammatory, antiapoptotic, and antiautophagy effects, which are mediated by the JAK2/STAT3β/PPARα pathway.

The apple dihydrochalcone phloretin suppresses growth and improves chemosensitivity of breast cancer cells via inhibition of cytoprotective autophagy

The inhibitory effect and mechanism of the apple dihydrochalcone, phloretin, on breast cancer cell growth were evaluated in in vitro conditions simulating complete nutrition and glucose-restriction, respectively. In two breast cancer cell lines with different histological backgrounds, phloretin consistently exhibited much stronger activity against cell growth in glucose-limiting than in full media. RNA-seq analysis showed that key autophagy-related genes were downregulated upon phloretin treatment in both estrogen-receptor-positive MCF7 and triple-negative MDA-MB-231 cells. Immunoblotting verified significantly decreased expression of LC3B-II by phloretin in low-glucose and glucose-free media, but not in full medium. Together with the use of two pharmacological autophagy inhibitors, chloroquine and 3-methyladenine, and confocal microscopy of breast cancer cell lines transfected with GFP-LC3B, phloretin demonstrated a strong capability to suppress autophagic flux, which was likely mediated through downregulation of mTOR/ULK1 signaling, whereas the expression of canonical autophagy regulators ATG5 and ATG7 was not significantly affected. Phloretin also reversed tamoxifen- and doxorubicin-induced cytoprotective autophagy in the breast cancer cell lines, and this was manifested in its synergistic growth inhibitory effect with these chemotherapeutic agents. Furthermore, it was able to restore or enhance the chemosensitivity of a tamoxifen-resistant cell line. Taken together, our study has, for the first time, revealed that phloretin could effectively suppress glucose-starvation- and chemotherapeutic-induced cytoprotective autophagy in breast cancer cell lines likely through downregulation of mTOR/ULK1 signaling.

Tumor-derived exosomal microRNA-7-5p enhanced by verbascoside inhibits biological behaviors of glioblastoma in vitro and in vivo

Verbascoside (VB), a glycosylated phenylpropane compound, has been widely used in traditional medicine showing anti-inflammatory and anti-tumor effects in many diseases. The current study aimed to investigate the mechanism underlying the inhibitor effect of VB on glioblastoma (GBM). We isolated and identified the tumor-derived exosomes (TEXs) secreted by GBM cells before and after treatment with VB, after which, we detected expression of microRNA (miR)-7-5p in cells and TEXs by qRT-PCR. Loss- and gain-function assays were conducted to determine the role of miR-7-5p in GBM cells with the proliferation, apoptosis, invasion, migration, and microtubule formation of GBM cells detected. A subcutaneous tumor model and tumor metastasis model of nude mice were established to validate the in vitro findings. We found that VB promoted the expression of miR-7-5p in GBM and transferred miR-7-5p to recipient GBM cells by exosomal delivery. Consequently, miR-7-5p downregulated epidermal growth factor receptor (EGFR) expression to inactivate the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway, causing inhibition in the proliferation, migration, invasion, and microtubule formation of GBM cells in vitro, as well as decline in tumor formation and metastasis in vivo. Overall, VB can promote the expression of miR-7-5p in GBM cells and transfer miR-7-5p via exosomes, thereby inhibiting the occurrence of GBM.