Gliomas and seizures

Etomidate inhibits tumor growth of glioblastoma by regulating M1 macrophage polarization

Glioblastoma (GBM) is a common primary central nervous system tumor. Although the multimodal integrated treatment for GBM has made great progress in recent years, the overall survival time of GBM is still short. Thus, novel treatments for GBM are worth further investigation and exploration. This study aimed to investigate the effects of etomidate on GBM tumor growth and the underlying mechanism. A xenograft tumor model was established and treated with etomidate to assess tumor growth. Immunohistochemistry (IHC) assay evaluated the positive rate of Ki67 cells in tumor tissues. Cell counting kit (CCK)-8 and EdU assays accessed the cell viability and proliferation. Immunofluorescence (IF) staining detected the distribution of macrophage markers in tumor tissues. The percentages of M1- and M2-like macrophages in tumor-associated macrophages (TAMs) and co-culture system (macrophages and GBM cells) were detected using flow cytometry. Macrophage polarization-related genes were measured using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Etomidate treatment inhibited the tumor growth, and increased the CD86+ cells but decreased the CD206+ cells in TAMs. The gene expression of M1 markers was increased in TAMs of etomidate-treated mice, whereas that of M2 markers was decreased. Moreover, etomidate treatment increased the number of CD86+ M1-like macrophages co-cultured with tumor cells but decreased that of CD206+ M2-like macrophages, with the upregulation of M1 markers and downregulation of M2 markers. Etomidate inhibited GBM tumor growth by promoting M1 macrophage polarization, suggesting a new insight into the clinical treatment of GBM.

Glioma-Induced Alterations in Excitatory Neurons are Reversed by mTOR Inhibition

Gliomas are highly aggressive brain tumors characterized by poor prognosis and composed of diffusely infiltrating tumor cells that intermingle with non-neoplastic cells in the tumor microenvironment, including neurons. Neurons are increasingly appreciated as important reactive components of the glioma microenvironment, due to their role in causing hallmark glioma symptoms, such as cognitive deficits and seizures, as well as their potential ability to drive glioma progression. Separately, mTOR signaling has been shown to have pleiotropic effects in the brain tumor microenvironment, including regulation of neuronal hyperexcitability. However, the local cellular-level effects of mTOR inhibition on glioma-induced neuronal alterations are not well understood. Here we employed neuron-specific profiling of ribosome-bound mRNA via 'RiboTag,' morphometric analysis of dendritic spines, and in vivo calcium imaging, along with pharmacological mTOR inhibition to investigate the impact of glioma burden and mTOR inhibition on these neuronal alterations. The RiboTag analysis of tumor-associated excitatory neurons showed a downregulation of transcripts encoding excitatory and inhibitory postsynaptic proteins and dendritic spine development, and an upregulation of transcripts encoding cytoskeletal proteins involved in dendritic spine turnover. Light and electron microscopy of tumor-associated excitatory neurons demonstrated marked decreases in dendritic spine density. In vivo two-photon calcium imaging in tumor-associated excitatory neurons revealed progressive alterations in neuronal activity, both at the population and single-neuron level, throughout tumor growth. This in vivo calcium imaging also revealed altered stimulus-evoked somatic calcium events, with changes in event rate, size, and temporal alignment to stimulus, which was most pronounced in neurons with high-tumor burden. A single acute dose of AZD8055, a combined mTORC1/2 inhibitor, reversed the glioma-induced alterations on the excitatory neurons, including the alterations in ribosome-bound transcripts, dendritic spine density, and stimulus evoked responses seen by calcium imaging. These results point to mTOR-driven pathological plasticity in neurons at the infiltrative margin of glioma - manifested by alterations in ribosome-bound mRNA, dendritic spine density, and stimulus-evoked neuronal activity. Collectively, our work identifies the pathological changes that tumor-associated excitatory neurons experience as both hyperlocal and reversible under the influence of mTOR inhibition, providing a foundation for developing therapies targeting neuronal signaling in glioma.

The role of neurotransmitters in glioblastoma multiforme-associated seizures

GBM, or glioblastoma multiforme, is a brain tumor that poses a great threat to both children and adults, being the primary cause of death related to brain tumors. GBM is often associated with epilepsy, which can be debilitating. Seizures and the development of epilepsy are the primary symptoms that have a severe impact on the quality of life for GBM patients. It is increasingly apparent that the nervous system plays an essential role in the tumor microenvironment for all cancer types, including GBM. In recent years, there has been a growing understanding of how neurotransmitters control the progression of gliomas. Evidence suggests that neurotransmitters and neuromodulators found in the tumor microenvironment play crucial roles in the excitability, proliferation, quiescence, and differentiation of neurons, glial cells, and neural stem cells. The involvement of neurotransmitters appears to play a significant role in various stages of GBM. In this review, the focus is on presenting updated knowledge and emerging ideas regarding the interplay between neurotransmitters and neuromodulators, such as glutamate, GABA, norepinephrine, dopamine, serotonin, adenosine, and their relationship with GBM and the seizures induced by this condition. The review aims to explore the current understanding and provide new insights into the complex interactions between these neurotransmitters and neuromodulators in the context of GBM-related seizures.

Unexplained Causes of Glioma-Associated Epilepsies: A Review of Theories and an Area for Research

Approximately 30% of glioma patients are able to survive beyond one year postdiagnosis. And this short time is often overshadowed by glioma-associated epilepsy. This condition severely impairs the patient's quality of life and causes great suffering. The genetic, molecular and cellular mechanisms underlying tumour development and epileptogenesis remain incompletely understood, leading to numerous unanswered questions. The various types of gliomas, namely glioblastoma, astrocytoma and oligodendroglioma, demonstrate distinct seizure susceptibility and disease progression patterns. Patterns have been identified in the presence of IDH mutations and epilepsy, with tumour location in cortical regions, particularly the frontal lobe, showing a more frequent association with seizures. Altered expression of TP53, MGMT and VIM is frequently detected in tumour cells from individuals with epilepsy associated with glioma. However, understanding the pathogenesis of these modifications poses a challenge. Moreover, hypoxic effects induced by glioma and associated with the HIF-1a factor may have a significant impact on epileptogenesis, potentially resulting in epileptiform activity within neuronal networks. We additionally hypothesise about how the tumour may affect the functioning of neuronal ion channels and contribute to disruptions in the blood-brain barrier resulting in spontaneous depolarisations.

Differential metabolic alterations in IDH1 mutant vs. wildtype glioma cells promote epileptogenesis through distinctive mechanisms

Glioma-related epilepsy (GRE) is a hallmark clinical presentation of gliomas with significant impacts on patient quality of life. The current standard of care for seizure management is comprised of anti-seizure medications (ASMs) and surgical resection. Seizures in glioma patients are often drug-resistant and can often recur after surgery despite total tumor resection. Therefore, current research is focused on the pro-epileptic pathological changes occurring in tumor cells and the peritumoral environment. One important contribution to seizures in GRE patients is metabolic reprogramming in tumor and surrounding cells. This is most evident by the significantly heightened seizure rate in patients with isocitrate dehydrogenase mutated (IDHmut) tumors compared to patients with IDH wildtype (IDHwt) gliomas. To gain further insight into glioma metabolism in epileptogenesis, this review compares the metabolic changes inherent to IDHmut vs. IDHwt tumors and describes the pro-epileptic effects these changes have on both the tumor cells and the peritumoral environment. Understanding alterations in glioma metabolism can help to uncover novel therapeutic interventions for seizure management in GRE patients.

Characteristics of Microstructural Changes Associated with Glioma Related Epilepsy: A Diffusion Tensor Imaging (DTI) Study

(1) Background: Glioma is the most common primary tumor in the central nervous system, and glioma-related epilepsy (GRE) is one of its common symptoms. The abnormalities of white matter fiber tracts are involved in attributing changes in patients with epilepsy (Rudà, R, 2012).This study aimed to assess frontal lobe gliomas' effects on the cerebral white matter fiber tracts. (2) Methods: Thirty patients with frontal lobe glioma were enrolled and divided into two groups (Ep and nEep). Among them, five patients were excluded due to apparent insular or temporal involvement. A set of 14 age and gender-matched healthy controls were also included. All the enrolled subjects underwent preoperative conventional magnetic resonance images (MRI) and diffusion tensor imaging (DTI). Furthermore, we used tract-based spatial statistics to analyze the characteristics of the white matter fiber tracts. (3) Results: The two patient groups showed similar patterns of mean diffusivity (MD) elevations in most regions; however, in the ipsilateral inferior fronto-occipital fasciculus (IFOF), superior longitudinal fasciculus (SLF), and superior corona radiata, the significant voxels of the EP group were more apparent than in the nEP group. No significant fractional anisotropy (FA) elevations or MD degenerations were found in the current study. (4) Conclusions: Gliomas grow and invade along white matter fiber tracts. This study assessed the effects of GRE on the white matter fiber bundle skeleton by TBSS, and we found that the changes in the white matter skeleton of the frontal lobe tumor-related epilepsy were mainly concentrated in the IFOF, SLF, and superior corona radiata. This reveals that GRE significantly affects the white matter fiber microstructure of the tumor.

Association of allergic diseases and epilepsy with risk of glioma, meningioma and acoustic neuroma: results from the INTERPHONE international case-control study

We investigated the association of allergic diseases and epilepsy with risk of brain tumours, in Interphone, a 13-country case-control study. Data were obtained from 2693 glioma cases, 2396 meningioma cases, and 1102 acoustic neuroma cases and their 6321 controls. Conditional logistic regression models were used to estimate pooled odds ratios (ORs) and their respective 95% confidence intervals (CIs), adjusted for education and time at interview. Reduced ORs were observed for glioma in relation to physician-diagnosed asthma (OR = 0.73; CI 0.58-0.92), hay fever (OR 0.72; CI 0.61-0.86), and eczema (OR 0.78, CI 0.64-0.94), but not for meningioma or acoustic neuroma. Previous diagnosis of epilepsy was associated with an increased OR for glioma (2.94; CI 1.87-4.63) and for meningioma (2.12; CI 1.27-3.56), but not for acoustic neuroma. This large-scale case-control study adds to the growing evidence that people with allergies have a lower risk of developing glioma, but not meningioma or acoustic neuroma. It also supports clinical observations of epilepsy prior to the diagnosis of glioma and meningioma.

Brain injuries can set up an epileptogenic neuronal network

Development of epilepsy or epileptogenesis promotes recurrent seizures. As of today, there are no effective prophylactic therapies to prevent the onset of epilepsy. Contributing to this deficiency of preventive therapy is the lack of clarity in fundamental neurobiological mechanisms underlying epileptogenesis and lack of reliable biomarkers to identify patients at risk for developing epilepsy. This limits the development of prophylactic therapies in epilepsy. Here, neural network dysfunctions reflected by oscillopathies and microepileptiform activities, including neuronal hyperexcitability and hypersynchrony, drawn from both clinical and experimental epilepsy models, have been reviewed. This review suggests that epileptogenesis reflects a progressive and dynamic dysfunction of specific neuronal networks which recruit further interconnected groups of neurons, with this resultant pathological network mediating seizure occurrence, recurrence, and progression. In the future, combining spatial and temporal resolution of neuronal non-invasive recordings from patients at risk of developing epilepsy, together with analytics and computational tools, may contribute to determining whether the brain is undergoing epileptogenesis in asymptomatic patients following brain injury.

Molecular dissection of the valproic acid effects on glioma cells

Many glioblastoma patients suffer from seizures why they are treated with antiepileptic agents. Valproic acid (VPA) is a histone deacetylase inhibitor that apart from its anticonvulsive effects in some retrospective studies has been suggested to lead to a superior outcome of glioblastoma patients. However, the exact molecular effects of VPA treatment on glioblastoma cells have not yet been deciphered. We treated glioblastoma cells with VPA, recorded the functional effects of this treatment and performed a global and unbiased next generation sequencing study on the chromatin (ChIP) and RNA level. 1) VPA treatment clearly sensitized glioma cells to temozolomide: A protruding VPA-induced molecular feature in this context was the transcriptional upregulation/reexpression of numerous solute carrier (SLC) transporters that was also reflected by euchromatinization on the histone level and a reexpression of SLC transporters in human biopsy samples after VPA treatment. DNA repair genes were adversely reduced. 2) VPA treatment, however, also reduced cell proliferation in temozolomide-naive cells: On the molecular level in this context we observed a transcriptional upregulation/reexpression and euchromatinization of several glioblastoma relevant tumor suppressor genes and a reduction of stemness markers, while transcriptional subtype classification (mesenchymal/proneural) remained unaltered. Taken together, these findings argue for both temozolomide-dependent and -independent effects of VPA. VPA might increase the uptake of temozolomide and simultaneously lead to a less malignant glioblastoma phenotype. From a mere molecular perspective these findings might indicate a surplus value of VPA in glioblastoma therapy and could therefore contribute an additional ratio for clinical decision making.

Antiepileptic drugs in patients with malignant brain tumor: beyond seizures and pharmacokinetics

In neurological malignancies, antiepileptic drugs (AEDs) are frequently used to control the seizure activity that accompanies the disorder. There is a growing body of evidence on the importance of AED selection for reasons other than pharmacokinetics (PK) properties. Epigenetic modifications may occur in glioblastomas, such as changes in gene methylation and histone acetylation states. Secondary mechanisms of AED drug action which impact these epigenetic modifications could play a significant role in patient survival outcomes. Both valproic acid (VPA) and carbamazepine have histone deacetylase (HDAC) inhibitory activities, and levetiracetam and VPA reduce the activity of O6-methylguanine-DNA methyltransferase (MGMT), a DNA-repair molecule implicated in resistance to alkylating agents used for chemotherapy. The use of AEDs for purposes other than seizure prophylaxis and their selection based on non-PK properties present a potential paradigm shift in the field of neuro-oncology.

Clinicopathological factors predictive of postoperative seizures in patients with gliomas

PURPOSE

Epilepsy is one of the most common manifestations in gliomas and has a severe effect on the life expectancy and quality of life of patients. The aim of our study was to assess the potential connections between clinicopathological factors and postoperative seizure.

METHOD

We retrospectively investigated a group of 147 Chinese high-grade glioma (HGG) patients with preoperative seizure to examine the correlation between postoperative seizure and clinicopathological factors and prognosis. Univariate analyses and multivariate logistic regression analyses were performed to identify factors associated with postoperative seizures. Survival function curves were calculated using the Kaplan-Meier method.

RESULTS

53 patients (36%) were completely seizure-free (Engel class I), and 94 (64%) experienced a postoperative seizure (Engel classes II, III, and IV). A Chi-squared analysis showed that anaplastic oligodendroglioma/anaplastic oligoastrocytoma (AO/AOA) (P=0.05), epidermal growth factor receptor (EGFR) expression (P=0.0004), O(6)-methylguanine DNA methyltransferase (MGMT) expression (P=0.011), and phosphatase and tensin homolog (PTEN) expression (P=0.045) were all significantly different. A logistic regression analysis showed that MGMT expression (P=0.05), EGFR expression (P=0.001), and AO/AOA (P=0.038) are independent factors of postoperative seizure. Patients with lower MGMT and EGFR expression and AO/AOA showed more frequent instances of postoperative seizure. Postoperative seizure showed no statistical significance on overall survival (OS) and progression-free survival (PFS).

CONCLUSION

Our study identified clinicopathological factors related to postoperative seizure in HGGs and found two predictive biomarkers of postoperative seizure: MGMT and EGFR. These findings provided insight treatment strategies aimed at prolonging survival and improving quality of life.

Third Ventricular Glioblastoma Multiforme: Case Report and Literature Review

Background Glioblastoma multiforme (GBM) typically presents in the supratentorial white matter, commonly within the centrum semiovale as a ring-enhancing lesion with areas of necrosis. An atypical presentation of this lesion, both anatomically as well as radiographically, is significant and must be part of the differential for a neoplasm in this anatomical location.

Case Description We present a case of a 62-year-old woman with headaches, increasing somnolence, and cognitive decline for several weeks. Magnetic resonance imaging demonstrated mild left ventricular dilatation with a well-marginated, homogeneous, and nonhemorrhagic lesion located at the ceiling of the third ventricle within the junction of the septum pellucidum and fornix, without exhibiting the typical radiographic features of hemorrhage or necrosis. Final pathology reports confirmed the diagnosis of GBM.

Conclusion This case report describes an unusual location for the most common primary brain neoplasm. Moreover, this case identifies the origin of a GBM related to the paracentral ventricular structures infiltrating the body of the fornix and leaves of the septum pellucidum. To our knowledge this report is the first reported case of a GBM found in this anatomical location with an entirely atypical radiographic presentation.

What is New in the Management of Epilepsy in Gliomas?

OPINION STATEMENT

Seizures represent a common symptom in low- and high-grade gliomas. Tumor location and histology influence the risk for epilepsy. Some molecular factors (BRAF V 600E mutations in glioneuronal tumors and IDH1/2 mutations in diffuse grade II and III gliomas) are molecular factors that are relevant for diagnosis and prognosis and have been associated with the risk of epilepsy as well. Glutamate plays a central role in epileptogenicity and growth of glial and glioneuronal tumors, based on the release of glutamate from tumor cells that enhances excitotoxicity, and a downregulation of the inhibitory GABAergic pathways. Several potential targets for therapy have been identified, and m-TOR inhibitors have already shown activity. Gross total resection is the strongest predictor of seizure freedom in addition to clinical factors, such as preoperative seizure duration, type, and control with antiepileptic drugs (AEDs). Radiotherapy and chemotherapy with alkylating agents (procarbazine, CCNU, vincristine, temozolomide) are effective in reducing the frequency of seizures in patients with pharmacoresistant epilepsy. Newer AEDs (in particular levetiracetam and lacosamide) seem to be better tolerated than the old AEDs (phenobarbital, phenytoin, carbamazepine), but randomized clinical trials are needed to prove their superiority in terms of efficacy.

Deficiency of very large G-protein-coupled receptor-1 is a risk factor of tumor-related epilepsy: a whole transcriptome sequencing analysis

The majority of patients with low-grade glioma (LGG) experience epileptic seizures as their initial symptom, while the underlying mechanisms of tumor-related seizures are still far from being fully understood. In addition to tumor type and location, genetic changes of LGGs are considered to be influential factors in causing epileptic seizures. Nevertheless, the molecular biomarkers associated with tumor-related epilepsy have rarely been identified. RNA sequence data from 80 patients with histologically confirmed LGG were collected from the Chinese glioma genome atlas database and significant differences in expression levels of 33 genes were found. One of the genes, Very large G-protein-coupled receptor-1 (VLGR1), had been previously associated with seizures. Therefore, we investigated the association between LGG-related epilepsy and VLGR1, which played a role in idiopathic epilepsy. The level of VLGR1 expression was compared between patients with epileptic seizures and those without using the reads per kilobase transcriptome per million method. To evaluate the prognostic role of VLGR1 gene expression, the progression-free survival was determined by the Kaplan-Meier method and a multivariate Cox model. We demonstrated that VLGR1 had a significantly lower expression level in patients with epileptic seizures compared to seizure-free patients (p = 0.003). Furthermore, VLGR1 was highly associated with the presence of seizures in a multivariate statistical model. However, VLGR1 could not serve as an independent prognostic factor to determine progression-free survival of LGG patients. Based on RNA sequence data analysis, our results suggest that low expression of VLGR1 is a significant risk factor of epileptic seizures in patients with LGG.

Peritumoral epilepsy: relating form and function for surgical success

Seizures are a prominent symptom in patients with both primary and secondary brain tumors. Medical management of seizure control in this patient group is problematic as the mechanisms linking tumorigenesis and epileptogenesis are poorly understood. It is possible that several mechanisms contribute to tumor-associated epileptic zone formation. In this review, we discuss key candidates that may be implicated in peritumoral epileptogenesis and, in so doing, hope to highlight areas for future research. Furthermore, we summarize the current role of antiepileptic medications in this type of epilepsy and examine the changes in surgical practice which may lead to improved seizure rates after tumor surgery. Lastly, we speculate on possible future preoperative and intraoperative considerations for improving seizure control after tumor resection.

Epilepsy in primary cerebral tumors: the characteristics of epilepsy at the onset (results from the PERNO study--Project of Emilia Romagna Region on Neuro-Oncology)

PURPOSE

To present new information on the semiology and short-term evolution of seizures associated with primary brain tumors (PBTs) in a prospective study.

METHODS

This study is a section of the PERNO study--Project of Emilia Romagna Region on Neuro-Oncology, the main aim of which is to collect prospectively all cases of PBTs occurring in the Emilia-Romagna region, northeast Italy (3,983,346 population) from January 2009 to December 2011, to allow epidemiologic, clinical, and biomolecular studies. The epilepsy section of the PERNO study included all the patients who experienced seizures, either as first symptom of the tumor or appearing during the course of the disease. Each patient was interviewed by the referring neurologist with a specific interest in epilepsy. The patients who entered the study were followed up with visits on a quarterly basis.

KEY FINDINGS

We collected 100 cases with full clinical, neuroradiologic, and pathologic data. The majority (79%) had high grade PBTs (glioblastoma in 50 cases), whereas the remaining patients had low-grade gliomas, mostly localized in the frontal (60%), temporal (38%), and parietal (28%) lobes. Seizures were the first symptom of the tumor in 72 cases. Overall, the initial seizures were tonic-clonic (48%) (without clear initial focal signs in more than half of the patients), focal motor (26%), complex partial (10%), and somatosensitive (8%). The majority of cases (60%) had isolated seizures or a low seizure frequency at the onset of the disease, whereas a high seizure frequency or status epilepticus was observed in 18% and 12% of cases, respectively. Ninety-two patients underwent surgical removal of the tumor, which was either radical (38%) or partial (53%). Seven patients underwent only cerebral biopsy. In the 72 patients in whom seizures were the first symptom, the mean time to the surgical treatment was 174 days, with a significant difference between high grade (95 days) and low grade (481 days) gliomas. At the time of our first observation, the majority of patients (69%) had already undergone surgical removal, with a mean follow-up of 3 months after the procedure. Overall, 39 patients (56%) were seizure free after tumor removal. The good outcome did not depend on presurgical seizure frequency or tumor type, although there was a trend for better results with low-grade PBTs.

SIGNIFICANCE

These data provide evidence that seizures are strictly linked to the tumoral lesion: They are the initial symptom of the tumor, reflect the tumor location and type, are usually resistant to antiepileptic treatment, and may disappear after the treatment of the lesion.