The pathobiology of glioma tumors

Telovelar Approach for the Surgical Resection of a Caudal Fossa Glioma in a Toy Poodle

A 7-year-old, 6.5 kg, neutered male toy poodle presented with tetraparesis, characterized by lower motor neuron signs in the forelimbs and upper motor neuron signs in the hindlimbs, along with seizures. Diagnostic imaging using magnetic resonance imaging (MRI) and computed tomography (CT) revealed a 1.4 cm × 1.4 cm × 2.2 cm mass in the fourth ventricle and caudal part of the brainstem. The surgical objective was to precisely remove masses compressing the cerebellum and brainstem. Using the telovelar approach, the tumor was partially excised, contrary to the goal of complete removal. Histopathological analysis confirmed the diagnosis of glioma. By the third postoperative day, the patient began to walk independently, and tetra-ataxia symptoms gradually decreased. Postoperative imaging confirmed the successful debulking of the tumor. By postoperative day 15, the patient showed normal gait, and adjuvant radiation therapy (RT) was initiated 2 weeks later. Unfortunately, the patient died 91 days after surgery, though the precise cause of death remains undetermined.

EFNB1 drives glioma progression and shapes the immune microenvironment: a potential prognostic biomarker

Gliomas, a heterogeneous group of tumors affecting the brain and spinal cord, present a significant clinical challenge. Ephrin B1 (EFNB1) has been implicated in various malignancies. However, its role in gliomas remained poorly understood. Hence, this study aimed to elucidate the connection between EFNB1 and the progression of glioma. A retrospective RNA-seq analysis was conducted by utilizing the data from glioma patients in the TCGA and CGGA databases. Kaplan-Meier survival analysis and multivariate regression models were employed to evaluate the prognostic significance of EFNB1. RT-PCR was used to quantify EFNB1 expression in glioma tissues and cell lines. Meanwhile, in vitro assays were carried out to assess its functional roles in glioma cells. Our findings demonstrated that EFNB1 expression was significantly elevated in gliomas and other cancers. Moreover, high EFNB1 expression was closely correlated with advanced clinical stages and poor prognosis. Notably, multivariate analysis identified EFNB1 as an independent prognostic factor for overall survival. KEGG pathway analysis suggested that EFNB1 was involved in critical biological processes, including the cell cycle, protein processing in the endoplasmic reticulum, Epstein-Barr virus infection, and Salmonella infection. Furthermore, EFNB1 expression was associated with immune cell infiltration, particularly Th2 cells, macrophages, and plasmacytoid dendritic cells. In glioma cells, EFNB1 expression was markedly increased. Consequently, functional experiments demonstrated that EFNB1 knockdown inhibited glioma cell proliferation, invasion, and migration. These results highlighted EFNB1 as a novel independent prognostic biomarker and suggest its potential role in shaping the immunological microenvironment of gliomas.

Nuclear NAD+ synthase nicotinamide mononucleotide adenylyltransferase 1 contributes to nuclear atypia and promotes glioma growth

Background

Glioma is a malignant primary brain tumor with a poor prognosis and short survival. NAD+ is critical for cancer growth; however, clinical trials targeting NAD+ biosynthesis had limited success, indicating the need for mechanistic characterization. Nuclear atypia, aberrations in the size and shape of the nucleus, is widely observed in cancer and is often considered a distinctive feature in diagnosis; however, the molecular underpinnings are unclear.

Methods

We carried out high-resolution immunohistochemical analyses on glioma tissue samples from 19 patients to analyze the expression of NAD+ synthase nicotinamide mononucleotide adenylyltransferase 1 (NMNAT1), and its correlation with nuclear atypia in gliomas. Utilizing a Drosophila model of glial neoplasia, we investigated the genetic role of nuclear NMNAT in glioma growth in vivo, elucidating the cellular mechanisms of NMNAT1 in promoting nuclear atypia and glioma growth.

Results

In low-grade glioma and glioblastoma, a higher transcription level of NMNAT1 is correlated with poorer disease-free survival. Samples of high-grade gliomas contained a higher percentage of glial cells enriched with NMNAT1 protein. We identified a specific correlation between nuclear NMNAT1 protein level with nuclear atypia. Mechanistic studies in human glioma cell lines and in vivo Drosophila model suggest that NMNAT1 disrupts the integrity of the nuclear lamina by altering the distribution of lamin A/C and promotes glioma growth.

Conclusions

Our study uncovers a novel functional connection between the NAD+ metabolic pathway and glioma growth, reveals the contribution of the NAD+ biosynthetic enzyme NMNAT1 to nuclear atypia, and underscores the role of nuclear NMNAT1 in exacerbating glioma pathology.

Cell-Based Glioma Models for Anticancer Drug Screening: From Conventional Adherent Cell Cultures to Tumor-Specific Three-Dimensional Constructs

Gliomas are a group of primary brain tumors characterized by their aggressive nature and resistance to treatment. Infiltration of surrounding normal tissues limits surgical approaches, wide inter- and intratumor heterogeneity hinders the development of universal therapeutics, and the presence of the blood-brain barrier reduces the efficiency of their delivery. As a result, patients diagnosed with gliomas often face a poor prognosis and low survival rates. The spectrum of anti-glioma drugs used in clinical practice is quite narrow. Alkylating agents are often used as first-line therapy, but their effectiveness varies depending on the molecular subtypes of gliomas. This highlights the need for new, more effective therapeutic approaches. Standard drug-screening methods involve the use of two-dimensional cell cultures. However, these models cannot fully replicate the conditions present in real tumors, making it difficult to extrapolate the results to humans. We describe the advantages and disadvantages of existing glioma cell-based models designed to improve the situation and build future prospects to make drug discovery comprehensive and more effective for each patient according to personalized therapy paradigms.

Study of Molecular Markers in Glioma and Their Association with Clinicopathological Features

CONTEXT

Central nervous system tumors are a major cause of morbidity and mortality worldwide. The most prevalent type of primary brain tumor is glioma. The exploration of significant genetic, epigenetic, and transcriptional abnormalities has not only improved our understanding of glioma pathogenesis but has also revealed that these molecular alterations can serve as useful diagnostic markers for more precise classification and are linked to better treatment response and prognosis. Hence, incorporating molecular markers into routine tumor classification is a major priority in modern glioma diagnostics.

AIM

The aim is to assess the mutation status of isocitrate dehydrogenase (IDH)-1, alpha-thalassemia/mental retardation syndrome X-linked (ATRX), and tumor protein 53 in glioma, and look for their association with various clinicopathological features.

METHODOLOGY

A single-center prospective cohort study, where all biopsies of glioma (January 2019 to July 2020) were evaluated, and immunohistochemistry was performed to assess the expression of IDH-1, ATRX, p53, and Ki-67 index. The data were analyzed using IBM SPSS-24 software.

RESULTS

Immunohistochemistry was performed in 123 consecutive cases of glioma. IDH-1 mutation was noted in 54 (43.9%) cases and these patients frequently presented with "seizures" (P = 0.006). The expression was maximum in World Health Organization (WHO) grade 2 tumors (65.4%) (P < 0.001), with the highest frequency in oligodendrogliomas (100% in WHO grade 2 and 3). Furthermore, these tumors showed lower proliferative indices (P = 0.001). ATRX mutation was noted in 59 (48%) and p53 overexpression was noted in 76 (61.8%) cases. These mutations were significantly associated with astrocytic phenotype (P = 0.03).

CONCLUSIONS

Molecular characterization of glioma is an important step in modern glioma diagnostics and immunohistochemistry can play an important role. IDH-1 mutation is commonly observed in adults, frontal lobe location, patients presenting with seizures, and WHO grade 2 tumors with the highest frequencies in oligodendrogliomas. ATRX and p53 can be used as surrogate markers for tumors of astrocytic lineage.

Pivotal Role of Cranial Irradiation-Induced Peripheral, Intrinsic, and Brain-Engrafting Macrophages in Malignant Glioma

Malignant (high-grade) gliomas are aggressive intrinsic brain tumors that diffusely infiltrate the brain parenchyma. They comprise of World Health Organization (WHO) grade III and IV gliomas. Ionizing radiation or irradiation (IR) is frequently utilized in the treatment of both primary as well as metastatic brain tumors. On the contrary, macrophages (MΦ) are the most copious infiltrating immune cells of all the different cell types colonizing glioma. MΦ at tumor milieu are referred to as tumor-associated macrophages (TAMΦ). In malignant gliomas milieu, TAMΦ are also polarized into two distinct phenotypes such as M1 TAMΦ or M2 TAMΦ, which are capable of inhibiting or promoting tumor growth, respectively. Cranial-IR such as x- and γ-IR are sufficient to induce the migration of peripherally derived MΦ into the brain parenchyma. The IR facilitate a more immunosuppressive milieu via the stimulation of efferocytosis in TAMΦ, and an upsurge of tumor cell engulfment by TAMΦ exhibited detrimental effect of the anti-tumoral immune response in glioma. The MΦ inside the tumor mass are associated with multiple phenomena that include IR resistance and enrichment of the M2 MΦ after IR is able to facilitate glioblastoma multiforme (GBM) recurrence. Reviews on the role of cranial IR-induced peripheral and brain-engrafting macrophages (BeMΦ) in glioma are lacking. Specifically, most studies on peripheral, intrinsic as well as beMΦ on IR focus on WHO grade III and IV. Thus, this review precisely focuses primary on WHO grade III as well as IV gliomas.

Efficacy and Cognitive Outcomes of Gamma Knife Radiosurgery in Glioblastoma Management for Elderly Patients

BACKGROUND

Gamma Knife Radiosurgery (GKRS), a specific type of Stereotactic Radiosurgery (SRS), has developed as a significant modality in the treatment of glioblastoma, particularly in conjunction with standard chemotherapy. The goal of this study is to evaluate the efficacy of combining GKRS with surgical resection and chemotherapy in enhancing therapeutic effects for glioblastoma patients aged 55 years and older.

METHODS

This prospective clinical study, conducted in accordance with the STROBE guidelines, involved 49 glioblastoma patients aged 55 years and older, treated between January 2013 and January 2023. Data were collected prospectively, and strict adherence to the STUPP protocol was maintained. Only patients who conformed to the STUPP protocol were included in the analysis. Due to concerns regarding the cognitive impairment associated with conventional radiotherapy, and at the patients' request, a radiosurgery plan was offered. Radiosurgery was administered for 4-8 weeks following surgical resection. Any patients who had not received previous radiotherapy received open surgical tumor removal, followed by GKRS along with adjuvant chemotherapy.

RESULTS

In this prospective clinical study of 49 glioblastoma patients aged 55 years and older, the average lifespan post-histopathological diagnosis was established at 22.3 months (95% CI: 12.0-28.0 months). The median time before disease progression was 14.3 months (95% CI: 13.0-29.7 months). The median duration until the first recurrence after treatment was 15.2 months, with documented cases varying between 4 and 33 months. The Gamma Knife Radiosurgery (GKRS) treatment involved a median marginal recommended dose of 12.5 Gy, targeting an average volume of 5.7 cm3 (range: 1.6-39 cm3). Local recurrence occurred in 21 patients, while distant recurrence was identified in 8 patients. Within the cohort, 34 patients were subjected to further therapeutic approaches, including reoperation, a second GKRS session, the administration of bevacizumab and irinotecan, and PCV chemotherapy. A cognitive function assessment revealed that the patients treated with GKRS experienced significantly less cognitive decline compared to the historical controls, who were treated with conventional radiotherapy. The median MMSE scores declined by 1.9 points over 12 months, and the median MoCA scores declined by 2.9 points.

CONCLUSION

This study demonstrates that Gamma Knife Radiosurgery (GKRS), when integrated with surgical resection and adjuvant chemotherapy, offers a substantial benefit for glioblastoma patients aged 55 years and older. The data reveal that GKRS not only prolongs overall survival and progression-free survival but also significantly reduces cognitive decline compared to conventional radiotherapy. These findings underscore the efficacy and safety of GKRS, advocating for its incorporation into standard treatment protocols for older glioblastoma patients. The potential of GKRS to improve patient outcomes while preserving cognitive function is compelling and warrants further research to optimize and confirm its role in glioblastoma management.

Understanding treatment preferences and cognitive outcomes in patients with gliomas

OBJECTIVE

Understanding how glioma patients value cognitive outcomes is essential to personalizing their treatment plans. The purpose of this study was to identify the modifiable cognitive functions most affected by treatment and most important to patient quality of life.

METHODS

Patients with gliomas were prospectively enrolled in focus groups and individual interviews using a standardized guide focusing on cognitive functions until saturation was achieved. Patient values and treatment preferences were elicited and compared to the frequency of reported deficits. NVivo natural language processing software was used to perform thematic qualitative analyses. Quantitative analysis with Fischer's exact test was used for each cognitive function to assess for an association between experiencing a deficit and rating that function as important to quality of life.

RESULTS

Twenty participants participated, of whom 60% were female. Racial identification consisted of 75% White, 15% Black/African American, and 10% Other Racial Identification. The cognitive functions most essential to the quality of life in this cohort were sense of self (80% of participants), memory (70% of participants), and communication (25% of participants). The functions that experienced the most deficits because of treatment were memory (65% of participants), concentration (65% of participants), and special senses (40% of participants). "Dealbreakers" to treatment were complete loss of independence, sense of self, and/or the ability to interact with loved ones. Fischer's exact test showed no associations between experiencing a cognitive function deficit and rating that function as important to quality of life.

CONCLUSIONS

Glioma patients in this study prioritized cognitive functions according to memory, personal identity, and their ability to communicate with loved ones independently of experiencing deficits in these functions. Further study should compare patient prioritization and decision-making between surgically curable and noncurable grade gliomas as well as investigate the quality of life benefits of incorporating the connectomics of highly valued cognitive functions in surgical planning.

Glucose metabolism in glioma: an emerging sight with ncRNAs

Glioma is a primary brain tumor that grows quickly, has an unfavorable prognosis, and can spread intracerebrally. Glioma cells rely on glucose as the major energy source, and glycolysis plays a critical role in tumorigenesis and progression. Substrate utilization shifts throughout glioma progression to facilitate energy generation and biomass accumulation. This metabolic reprogramming promotes glioma cell proliferation and metastasis and ultimately decreases the efficacy of conventional treatments. Non-coding RNAs (ncRNAs) are involved in several glucose metabolism pathways during tumor initiation and progression. These RNAs influence cell viability and glucose metabolism by modulating the expression of key genes of the glycolytic pathway. They can directly or indirectly affect glycolysis in glioma cells by influencing the transcription and post-transcriptional regulation of oncogenes and suppressor genes. In this review, we discussed the role of ncRNAs in the metabolic reprogramming of glioma cells and tumor microenvironments and their abnormal expression in the glucometabolic pathway in glioma. In addition, we consolidated the existing theoretical knowledge to facilitate the use of this emerging class of biomarkers as biological indicators and potential therapeutic targets for glioma.

The importance of the circRNA/Wnt axis in gliomas: Biological functions and clinical opportunities

Gliomas are among the most common cancers in the central nervous system, arising through various signaling pathways. One significant pathway is Wnt signaling, a tightly regulated process that plays a crucial role in gliomagenesis and development. The current study aims to explore the relationship between circular RNAs (circRNAs) and the Wnt/β-catenin signaling pathway in gliomas, considering the growing recognition of circRNAs in disease pathogenesis. A comprehensive review of recent research was conducted to investigate the roles of circRNAs in gliomas, focusing on their expression patterns and interactions with the Wnt signaling pathway. The analysis included studies examining circRNAs' function as microRNA sponges and their impact on glioma biology. The findings reveal that circRNAs are differentially expressed in gliomas and significantly influence the occurrence, growth, and metastasis of these tumors. Specifically, circRNAs interact with the Wnt signaling pathway, affecting glioma development and progression. This interaction highlights the importance of circRNAs in glioma pathophysiology. Understanding the regulatory network involving circRNAs and Wnt signaling offers valuable insights into glioma pathophysiology. CircRNAs hold promise as diagnostic and prognostic biomarkers and may serve as targets for novel therapeutic strategies in glioma treatment.

PTX3 activates POSTN and promotes the progression of glioblastoma via the MAPK/ERK signalling axis

BACKGROUND

Intrinsic brain tumours such as glioblastoma (GBM) are believed to develop from neuroglial stem or progenitor cells. GBM accounts for approximately half of gliomas. GBM has a poor prognosis and a low 5-year survival rate. Pentraxin 3 (PTX3) is overexpressed in GBM, but the potential mechanism is unclear.

METHODS

Glioblastoma data from the TCGA and CGGA databases were used to analyse PTX3 expression. Subsequently, in vivo and in vitro experiments were conducted to verify the effect of PTX3 silencing in glioma cells on EMT like process and GSC maintenance. The JASPAR database was used to predict the downstream genes of PTX3. POSTN is a novel target gene of PTX3 in gliomas, and this finding was validated using a luciferase reporter gene assay. Western blotting and KEGG enrichment analysis were used to predict the downstream pathway of POSTN, and it was found that the MAPK/ERK pathway might be related to the function of POSTN.

RESULTS

GBM tissues have higher levels of PTX3 expression than normal brain tissues (NBTs). In functional tests, PTX3 promoted the EMT like process of GBM cells while maintaining the stem cell characteristics of GBM stem cells and enhancing their self-renewal. Moreover, we performed a dual luciferase reporter experiment to confirm that PTX3 binds to the POSTN promoter region. In addition, the expression of key proteins in the MAPK/ERK signalling pathway was increased after PTX3 overexpression.

CONCLUSION

POSTN is a direct target of PTX3 that promotes GBM growth via the MAPK/ERK signalling pathway.

Marker-controlled watershed algorithm and fuzzy C-means clustering machine learning: automated segmentation of glioblastoma from MRI images in a case series

INTRODUCTION AND IMPORTANCE

Automated segmentation of glioblastoma multiforme (GBM) from MRI images is crucial for accurate diagnosis and treatment planning. This paper presents a new and innovative approach for automating the segmentation of GBM from MRI images using the marker-controlled watershed segmentation (MCWS) algorithm.

CASE PRESENTATION AND METHODS

The technique involves several image processing techniques, including adaptive thresholding, morphological filtering, gradient magnitude calculation, and regional maxima identification. The MCWS algorithm efficiently segments images based on local intensity structures using the watershed transform, and fuzzy c-means (FCM) clustering improves segmentation accuracy. The presented approach achieved improved segmentation accuracy in detecting and segmenting GBM tumours from axial T2-weighted (T2-w) MRI images, as demonstrated by the mean characteristics performance metrics for GBM segmentation (sensitivity: 0.9905, specificity: 0.9483, accuracy: 0.9508, precision: 0.5481, F_measure: 0.7052, and jaccard: 0.9340).

CLINICAL DISCUSSION

The results of this study underline the importance of reliable and accurate image segmentation for effective diagnosis and treatment planning of GBM tumours.

CONCLUSION

The MCWS technique provides an effective and efficient approach for the segmentation of challenging medical images.

Exosomes in Glioma: Unraveling Their Roles in Progression, Diagnosis, and Therapy

Gliomas, the most prevalent primary malignant brain tumors, present a challenging prognosis even after undergoing surgery, radiation, and chemotherapy. Exosomes, nano-sized extracellular vesicles secreted by various cells, play a pivotal role in glioma progression and contribute to resistance against chemotherapy and radiotherapy by facilitating the transportation of biological molecules and promoting intercellular communication within the tumor microenvironment. Moreover, exosomes exhibit the remarkable ability to traverse the blood-brain barrier, positioning them as potent carriers for therapeutic delivery. These attributes hold promise for enhancing glioma diagnosis, prognosis, and treatment. Recent years have witnessed significant advancements in exosome research within the realm of tumors. In this article, we primarily focus on elucidating the role of exosomes in glioma development, highlighting the latest breakthroughs in therapeutic and diagnostic approaches, and outlining prospective directions for future research.

Multiparametric Radiogenomic Model to Predict Survival in Patients with Glioblastoma

BACKGROUND

Clinical, histopathological, and imaging variables have been associated with prognosis in patients with glioblastoma (GBM). We aimed to develop a multiparametric radiogenomic model incorporating MRI texture features, demographic data, and histopathological tumor biomarkers to predict prognosis in patients with GBM.

METHODS

In this retrospective study, patients were included if they had confirmed diagnosis of GBM with histopathological biomarkers and pre-operative MRI. Tumor segmentation was performed, and texture features were extracted to develop a predictive radiomic model of survival (<18 months vs. ≥18 months) using multivariate analysis and Least Absolute Shrinkage and Selection Operator (LASSO) regularization to reduce the risk of overfitting. This radiomic model in combination with clinical and histopathological data was inserted into a backward stepwise logistic regression model to assess survival. The diagnostic performance of this model was reported for the training and external validation sets.

RESULTS

A total of 116 patients were included for model development and 40 patients for external testing validation. The diagnostic performance (AUC/sensitivity/specificity) of the radiomic model generated from seven texture features in determination of ≥18 months survival was 0.71/69.0/70.3. Three variables remained as independent predictors of survival, including radiomics (p = 0.004), age (p = 0.039), and MGMT status (p = 0.025). This model yielded diagnostic performance (AUC/sensitivity/specificity) of 0.77/81.0/66.0 (training) and 0.89/100/78.6 (testing) in determination of survival ≥ 18 months.

CONCLUSIONS

Results show that our radiogenomic model generated from radiomic features at baseline MRI, age, and MGMT status can predict survival ≥ 18 months in patients with GBM.

Efficacy and indications of gamma knife radiosurgery for recurrent low-and high-grade glioma

PURPOSE

To investigate the indications and efficacy of gamma knife radiosurgery (GKRS) as a salvage treatment for recurrent low-and high-grade glioma.

METHODS

This retrospective study of 107 patients with recurrent glioma treated with GKRS between 2009 and 2022, including 68 high-grade glioma (HGG) and 39 low-grade glioma (LGG) cases. The Kaplan-Meier method was used to calculate the overall survival (OS) and progression-free survival (PFS). The log-rank test was used to analyze the multivariate prognosis of the Cox proportional hazards model. Adverse reactions were evaluated according to the Common Terminology Criteria for Adverse Events version 4.03. The prognostic value of main clinical features was estimated, including histopathology, Karnofsky performance status (KPS), recurrence time interval, target location, two or more GKRS, surgery for recurrence, site of recurrence, left or right side of the brain and so on.

RESULTS

The median follow-up time was 74.5 months. The median OS and PFS were 17.0 months and 5.5 months for all patients. The median OS and PFS were 11.0 months and 5.0 months for HGG, respectively. The median OS and PFS were 49.0 months and 12.0 months for LGG, respectively. Multivariate analysis showed that two or more GKRS, left or right side of the brain and brainstem significantly affected PFS. Meanwhile, the KPS index, two or more GKRS, pathological grade, and brainstem significantly affected OS. Stratified analysis showed that surgery for recurrence significantly affected OS and PFS for LGG. KPS significantly affected OS and PFS for HGG. No serious adverse events were noted post-GKRS.

CONCLUSION

GKRS is a safe and effective salvage treatment for recurrent glioma. Moreover, it can be applied after multiple recurrences with tolerable adverse effects.

Navigating the Gene Co-Expression Network and Drug Repurposing Opportunities for Brain Disorders Associated with Neurocognitive Impairment

Neurocognitive impairment refers to a spectrum of disorders characterized by a decline in cognitive functions such as memory, attention, and problem-solving, which are often linked to structural or functional abnormalities in the brain. While its exact etiology remains elusive, genetic factors play a pivotal role in disease onset and progression. This study aimed to identify highly correlated gene clusters (modules) and key hub genes shared across neurocognition-impairing diseases, including Alzheimer's disease (AD), Parkinson's disease with dementia (PDD), HIV-associated neurocognitive disorders (HAND), and glioma. Herein, the microarray datasets AD (GSE5281), HAND (GSE35864), glioma (GSE15824), and PD (GSE7621) were used to perform Weighted Gene Co-expression Network Analysis (WGCNA) to identify highly preserved modules across the studied brain diseases. Through gene set enrichment analysis, the shared modules were found to point towards processes including neuronal transcriptional dysregulation, neuroinflammation, protein aggregation, and mitochondrial dysfunction, hallmarks of many neurocognitive disorders. These modules were used in constructing protein-protein interaction networks to identify hub genes shared across the diseases of interest. These hub genes were found to play pivotal roles in processes including protein homeostasis, cell cycle regulation, energy metabolism, and signaling, all associated with brain and CNS diseases, and were explored for their drug repurposing experiments. Drug repurposing based on gene signatures highlighted drugs including Dorzolamide and Oxybuprocaine, which were found to modulate the expression of the hub genes in play and may have therapeutic implications in neurocognitive disorders. While both drugs have traditionally been used for other medical purposes, our study underscores the potential of a combined WGCNA and drug repurposing strategy for searching for new avenues in the simultaneous treatment of different diseases that have similarities in gene co-expression networks.

Neutrophil membrane-based nanotherapeutics: Propitious paradigm shift in the management of cancer

Cancer is the leading cause of death across the globe, with 19.3 million new cancer cases and 10 million deaths in the year 2020. Conventional treatment modalities have numerous pitfalls, such as off-site cytotoxicity and poor bioavailability. Nanocarriers (NCs) have been explored to deliver various therapeutic moieties such as chemotherapeutic agents and photothermal agents, etc. However, several limitations, such as rapid clearance by the reticuloendothelial system, poor extravasation into the tumor microenvironment, and low systemic half-life are roadblocks to successful clinical translation. To circumvent the pitfalls of currently available treatment modalities, neutrophil membrane (NM)-based nanotherapeutics have emerged as a promising platform for cancer management. Their versatile features such as natural tumor tropism, tumor-specific accumulation, and prevention from rapid clearance owing to their autologous nature make them an effective anticancer NCs. In this manuscript, we have discussed various methods for isolation, coating and characterization of NM. We have discussed the role of NM-coated nanotherapeutics as neoadjuvant and adjuvant in different treatment modalities, such as chemotherapy, photothermal and photodynamic therapies with rationales behind their inclusion. Clinical hurdles faced during the bench-to-bedside translation with possible solutions have been discussed. We believe that in the upcoming years, NM-coated nanotherapeutics will open a new horizon in cancer management.

Histological and molecular classifications of pediatric glioma with time-dependent diffusion MRI-based microstructural mapping

BACKGROUND

Gliomas are the most common type of central nervous system tumors in children, and the combination of histological and molecular classification is essential for prognosis and treatment. Here, we proposed a newly developed microstructural mapping technique based on diffusion-time-dependent diffusion MRI td-dMRI theory to quantify tumor cell properties and tested these microstructural markers in identifying histological grade and molecular alteration of H3K27.

METHODS

This prospective study included 69 pediatric glioma patients aged 6.14 ± 3.25 years old, who underwent td-dMRI with pulsed and oscillating gradient diffusion sequences on a 3T scanner. dMRI data acquired at varying tds were fitted into a 2-compartment microstructural model to obtain intracellular fraction (fin), cell diameter, cellularity, etc. Apparent diffusivity coefficient (ADC) and T1 and T2 relaxation times were also obtained. H&E stained histology was used to validate the estimated microstructural properties.

RESULTS

For histological classification of low- and high-grade pediatric gliomas, the cellularity index achieved the highest area under the receiver-operating-curve (AUC) of 0.911 among all markers, while ADC, T1, and T2 showed AUCs of 0.906, 0.885, and 0.886. For molecular classification of H3K27-altered glioma in 39 midline glioma patients, cell diameter showed the highest discriminant power with an AUC of 0.918, and the combination of cell diameter and extracellular diffusivity further improved AUC to 0.929. The td-dMRI estimated fin correlated well with the histological ground truth with r = 0.7.

CONCLUSIONS

The td-dMRI-based microstructural properties outperformed routine MRI measurements in diagnosing pediatric gliomas, and the different microstructural features showed complementary strength in histological and molecular classifications.

Mathematical modelling of the dynamics of image-informed tumor habitats in a murine model of glioma

Tumors exhibit high molecular, phenotypic, and physiological heterogeneity. In this effort, we employ quantitative magnetic resonance imaging (MRI) data to capture this heterogeneity through imaging-based subregions or "habitats" in a murine model of glioma. We then demonstrate the ability to model and predict the growth of the habitats using coupled ordinary differential equations (ODEs) in the presence and absence of radiotherapy. Female Wistar rats (N = 21) were inoculated intracranially with 10⁶ C6 glioma cells, a subset of which received 20 Gy (N = 5) or 40 Gy (N = 8) of radiation. All rats underwent diffusion-weighted and dynamic contrast-enhanced MRI at up to seven time points. All MRI data at each visit were subsequently clustered using k-means to identify physiological tumor habitats. A family of four models consisting of three coupled ODEs were developed and calibrated to the habitat time series of control and treated rats and evaluated for predictive capability. The Akaike Information Criterion was used for model selection, and the normalized sum-of-square-error (SSE) was used to evaluate goodness-of-fit in model calibration and prediction. Three tumor habitats with significantly different imaging data characteristics (p < 0.05) were identified: high-vascularity high-cellularity, low-vascularity high-cellularity, and low-vascularity low-cellularity. Model selection resulted in a five-parameter model whose predictions of habitat dynamics yielded SSEs that were similar to the SSEs from the calibrated model. It is thus feasible to mathematically describe habitat dynamics in a preclinical model of glioma using biology-based ODEs, showing promise for forecasting heterogeneous tumor behavior.

Regulation of pleiotropic physiological roles of nitric oxide signaling

Nitric Oxide (NO) is a highly diffusible, ubiquitous signaling molecule and a free radical that is naturally synthesized by our body. The pleiotropic effects of NO in biological systems are due to its reactivity with different molecules, such as molecular oxygen (O₂), superoxide anion, DNA, lipids, and proteins. There are several contradictory findings in the literature pertaining to its role in oncology. NO is a Janus-faced molecule shown to have both tumor promoting and tumoricidal effects, which depend on its concentration, duration of exposure, and location. A high concentration is shown to have cytotoxic effects by triggering apoptosis, and at a low concentration, NO promotes angiogenesis, metastasis, and tumor progression. Upregulated NO synthesis has been implicated as a causal factor in several pathophysiological conditions including cancer. This dichotomous effect makes it highly challenging to discover its true potential in cancer biology. Understanding the mechanisms by which NO acts in different cancers helps to develop NO based therapeutic strategies for cancer treatment. This review addresses the physiological role of this molecule, with a focus on its bimodal action in various types of cancers.

Key Genes Are Associated with the Prognosis of Glioma, and Melittin Can Regulate the Expression of These Genes in Glioma U87 Cells

Glioma is the most common primary tumor of the central nervous system. Currently, there is no effective treatment for glioma. Melittin (MT) is the main component of bee venom, which was found to have therapeutic effects on a variety of tumors. In this study, we explored the relationship between key genes regulated by MT and the prognosis of glioma. In cultured glioma U87 and U251 cells, MT inhibited cell proliferation and induces cell apoptosis in a time- and concentration-dependent manner. RNA-seq revealed that MT upregulated 11 genes and downregulated 37 genes. These genes are mainly enriched in cell membrane signaling pathways, such as surface membrane, membrane-enclosed organelles, integral component of membrane, PPAR signaling pathway, and voltage-gated potassium channel. PPI network analysis and literature analysis of 48 genes were performed, and 8 key genes were identified, and these key genes were closely associated with clinical prognosis. Overexpression of PCDH18, PPL, DEPP1, VASN, KCNE4, MYBPH, and C5AR2 genes or low expression of MARCH4 gene in glioma patients was associated with poor survival. qPCR confirmed that MT can regulate the expression of these genes in glioma U87 cells. This study indicated that MT significantly inhibited the growth and regulated the expression of PCDH18, C5AR2, VASN, DEPP1, MYBPH, KCNE4, PPL, and MARCH4 genes in glioma U87 cells in vitro. These genes are closely related to the prognosis of patients with glioma and can be used as independent prognostic factors in patients with glioma. MT is a potential drug for the treatment of glioma.

Polymeric and small molecule-conjugates of temozolomide as improved therapeutic agents for glioblastoma multiforme

Temozolomide (TMZ), an imidazotetrazine, is a second-generation DNA alkylating agent used as a first-line treatment of glioblastoma multiforme (GBM). It was approved by FDA in 2005 and declared a blockbuster drug in 2008. Although TMZ has shown 100% oral bioavailability and crosses the blood-brain barrier effectively, however it suffers from limitations such as a short half-life (∼1.8 h), rapid metabolism, and lesser accumulation in the brain (∼10-20%). Additionally, development of chemoresistance has been associated with its use. Since it is a potential chemotherapeutic agent with an unmet medical need, advanced delivery strategies have been explored to overcome the associated limitations of TMZ. Nanocarriers including liposomes, solid lipid nanoparticles (SLNs), nanostructure lipid carriers (NLCs), and polymeric nanoparticles have demonstrated their ability to improve its circulation time, stability, tissue-specific accumulation, sustained release, and cellular uptake. Because of the appreciable water solubility of TMZ (∼5 mg/mL), the physical loading of TMZ in these nanocarriers is always challenging. Alternatively, the conjugation approach, wherein TMZ has been conjugated to polymers or small molecules, has been explored with improved outcomes in vitro and in vivo. This review emphasized the practical evidence of the conjugation strategy to improve the therapeutic potential of TMZ in the treatment of glioblastoma multiforme.

Usage of Nanoparticles to Alter Neutrophils' Function for Therapy

Neutrophils, the most abundant white blood cells in the human body, are important immune cells responsible for the innate immune response. Neutrophils can migrate to inflammatory areas, such as tumor sites and infection sites, because of chemotaxis. Neutrophil-based nanomaterials, such as neutrophil-nanomaterial composites and neutrophil membrane-based nanomaterials, can help the drug or imaging agent gather in the inflammatory area with the help of chemotaxis. In addition, some nanomaterials can interfere with the function of neutrophils to treat tissue damage caused by excessive local accumulation of neutrophils. This review focuses on the interaction between nanomaterials and neutrophils as well as the applications of neutrophil-based nanomaterials and neutrophil-interfering nanomaterials.

Development and validation of a prognostic gene expression signature for lower-grade glioma following surgery and adjuvant radiotherapy

BACKGROUND AND PURPOSE

Standard of care for lower-grade glioma (LGG) is maximal safe resection and risk-adaptive adjuvant therapy. While patients who benefit the most from adjuvant chemotherapy have been elucidated in prospective randomized studies, comparable insights for adjuvant radiotherapy (RT) are lacking. We sought to identify and validate patterns of gene expression that are associated with differential outcomes among LGG patients treated by RT from two large genomics databases.

MATERIALS AND METHODS

Patients from The Cancer Genome Atlas (TCGA) with LGG (WHO grade II-III glioma) treated by surgery and adjuvant RT were randomized 1:1 to a discovery cohort or an internal validation cohort. Using the discovery cohort only, associations between tumor RNA-seq expression and progression-free survival (PFS) as well as overall survival (OS) were evaluated with adjustment for clinicopathologic covariates. A Genomic Risk Score (GRS) was then constructed from the expression levels of top genes also screened for involvement in glioma carcinogenesis. The prognostic value of GRS was further assessed in the internal validation cohort of TCGA and a second distinct database, compiled by the Chinese Glioma Genome Association (CGGA).

RESULTS

From TCGA, 289 patients with LGG received adjuvant RT alone (38 grade II, 30 grade III) or chemoradiotherapy (CRT) (51 grade II, 170 grade III) between 2009 and 2015. From CGGA, 178 patients with LGG received adjuvant RT alone (40 grade II, 13 grade III) or CRT (41 grade II, 84 grade III) between 2004 and 2016. The genes comprising GRS are involved in MAP kinase activity, T cell chemotaxis, and cell cycle transition: MAP3K15, MAPK10, CCL3, CCL4, and ADAMTS1. High GRS, defined as having a GRS in the top third, was significantly associated with poorer outcomes independent of age, sex, glioma histology, WHO grade, IDH mutation, 1p/19q co-deletion, and chemotherapy status in the discovery cohort (PFS HR 1.61, 95% CI 1.10-2.36, P=0.014; OS HR 2.74, 95% CI 1.68-4.47, P<0.001). These findings were replicated in the internal validation cohort (PFS HR 1.58, 95% CI 1.05-2.37, P=0.027; OS HR 1.84, 95% CI 1.13-3.00, P=0.015) and the CGGA external validation cohort (OS HR 1.72, 95% CI 1.27-2.34, P<0.001). Association between GRS and outcomes was observed only among patients who underwent RT, in both TCGA and CGGA.

CONCLUSION

This study successfully identified an expression signature of five genes that stratified outcomes among LGG patients who received adjuvant RT, with two rounds of validation leveraging independent genomics databases. Expression levels of the highlighted genes were associated with PFS and OS only among patients whose treatment included RT, but not among those with omission of RT, suggesting that expression of these genes may be predictive of radiation treatment response. While additional prospective studies are warranted, interrogation of these genes may be considered in the multidisciplinary management of LGG.

Glioblastoma‐educated mesenchymal stem‐like cells promote glioblastoma infiltration via extracellular matrix remodelling in the tumour microenvironment

Background

The biological function of mesenchymal stem‐like cells (MSLCs), a type of stromal cells, in the regulation of the tumour microenvironment is unclear. Here, we investigated the molecular mechanisms underlying extracellular matrix (ECM) remodelling and crosstalk between MSLCs and glioblastomas (GBMs) in tumour progression.

Methods

In vitro and in vivo co‐culture systems were used to analyze ECM remodelling and GBM infiltration. In addition, clinical databases, samples from patients with GBM and a xenografted mouse model of GBM were used.

Results

Previous studies have shown that the survival of patients with GBM from whom MSLCs could be isolated is substantially shorter than that of patients from whom MSLCs could not be isolated. Therefore, we determined the correlation between changes in ECM‐related gene expression in MSLC‐isolatable patients with that in MSLC non‐isolatable patients using gene set enrichment analysis (GSEA). We found that lysyl oxidase (LOX) and COL1A1 expressions increased in MSLCs via GBM‐derived clusters of differentiation 40 ligand (CD40L). Mechanistically, MSLCs are reprogrammed by the CD40L/CD40/NFκB2 signalling axis to build a tumour infiltrative microenvironment involving collagen crosslinking. Importantly, blocking of CD40L by a neutralizing antibody‐suppressed LOX expression and ECM remodelling, decreasing GBM infiltration in mouse xenograft models. Clinically, high expression of CD40L, clusters of differentiation 40 (CD40) and LOX correlated with poor survival in patients with glioma. This indicated that GBM‐educated MSLCs promote GBM infiltration via ECM remodelling in the tumour microenvironment.

Conclusion

Our findings provide mechanistic insights into the pro‐infiltrative tumour microenvironment produced by GBM‐educated MSLCs and highlight a potential therapeutic target that can be used for suppressing GBM infiltration.

Inhibition of PTPN21 has antitumor effects in glioma by restraining the EGFR/PI3K/AKT pathway

Protein tyrosine phosphatase non-receptor type 21 (PTPN21) has been recognised as a new tumour-associated protein that is implicated in diverse tumours. However, the correlation between PTPN21 and glioma remains unaddressed. This investigation focused on the relevance of PTPN21 in glioma. The Cancer Genome Atlas (TCGA) analysis identified PTPN21 as being up-regulated in glioma tissue. The elevation of PTP21 in glioma was validated by evaluating clinical specimen. Kaplan-Meier plot analysis revealed that a high PTPN21 level predicted poor survival rate in glioma patient. Silencing of PTPN21 produced remarkable anticancer effects in glioma cells including proliferation inhibition, cell cycle arrest, metastasis suppression and enhanced chemosensitivity. Mechanistic studies uncovered that PTPN21 contributes to mediation of the phosphatidyl-inositole-3 kinase (PI3K)/AKT pathway via the regulation of epidermal growth factor receptor (EGFR). Restraint of EGFR diminished PTPN21 overexpression-induced promoting effect on PI3K/AKT pathway. Reactivation of AKT reversed PTPN21 silencing-evoked antitumor effect. The tumorigenic potential of PTPN21-silenced glioma cells in vivo was markedly compromised. In summary, this study demonstrates that silencing of PTPN21 produces remarkable anticancer effects in glioma by restraining the EGFR/PI3K/AKT pathway.

Integrin α3β1 promotes vessel formation of glioblastoma-associated endothelial cells through calcium-mediated macropinocytosis and lysosomal exocytosis

Therapeutic targeting of angiogenesis in glioblastoma has yielded mixed outcomes. Investigation of tumor-associated angiogenesis has focused on the factors that stimulate the sprouting, migration, and hyperproliferation of the endothelial cells. However, little is known regarding the processes underlying the formation of the tumor-associated vessels. To address this issue, we investigated vessel formation in CD31+ cells isolated from human glioblastoma tumors. The results indicate that overexpression of integrin α3β1 plays a central role in the promotion of tube formation in the tumor-associated endothelial cells in glioblastoma. Blocking α3β1 function reduced sprout and tube formation in the tumor-associated endothelial cells and vessel density in organotypic cultures of glioblastoma. The data further suggest a mechanistic model in which integrin α3β1-promoted calcium influx stimulates macropinocytosis and directed maturation of the macropinosomes in a manner that promotes lysosomal exocytosis during nascent lumen formation. Altogether, our data indicate that integrin α3β1 may be a therapeutic target on the glioblastoma vasculature.

Induction of cancer cell stemness in glioma through glycolysis and the long noncoding RNA HULC-activated FOXM1/AGR2/HIF-1α axis

Gliomas are the most common primary intracranial tumor, accounting for more than 70% of brain malignancies. Studies indicate that highly upregulated in liver cancer (HULC), a long noncoding RNA (lncRNA), functions as an oncogene in gliomas. However, the underlying mechanism of HULC in gliomas remains under-studied and was subsequently investigated in the current study. Brain tissues were clinically collected from 50 patients with glioblastoma (GBM) and 35 patients with acute craniocerebral injury, followed by immunohistochemical detection of the expression patterns of Forkhead box M1 (FOXM1), anterior gradient 2 (AGR2), and hypoxia-inducible factor-1α (HIF-1α). After flow cytometry-based sorting of the CD133⁺ glioma stem cells (GSCs) from the U251 cell line, the obtained cells were subjected to lentivirus infection. Afterwards, the proliferation, stemness, and apoptosis of GSCs were evaluated using sphere formation, immunofluorescence, and flow cytometry assays, respectively. In addition, the interactions among HULC, FOXM1, AGR2, and HIF-1α were identified using RNA immunoprecipitation (RIP), RNA pull-down, Chromatin immunoprecipitation (ChIP), IP, and dual luciferase reporter assays. Last, the specific effects were validated in vivo. HULC was upregulated in GBM tissues and GSCs, which may promote the progression of glioma. On the other hand, silencing of HULC reduced the stemness, inhibited the proliferation, and promoted the apoptosis and differentiation of GSCs. In addition, HULC further stabilized FOXM1 expression in GSCs through ubiquitination, while FOXM1 activated AGR2 transcription to promote HIF-1α expression. Moreover, HULC promoted the glycolysis and stemness of GSCs through its regulation of the FOXM1/AGR2/HIF-1α axis, consequently exacerbating the occurrence and development of glioma. The findings obtained in our study indicate that HULC stabilizes the FOXM1 protein by ubiquitination to upregulate the expression of AGR2 and HIF-1α, which further promote the glycolysis of and maintain the stemness of GSCs, to enhance the tumorigenicity of GSCs, highlighting a novel therapeutic target for glioma.

Prognostic Features of the Tumor Immune Microenvironment in Glioma and Their Clinical Applications: Analysis of Multiple Cohorts

Glioma is the most common malignant tumor of the central nervous system. Tumor purity is a source of important prognostic factor for glioma patients, showing the key roles of the microenvironment in glioma prognosis. In this study, we systematically screened functional characterization related to the tumor immune microenvironment and constructed a risk model named Glioma MicroEnvironment Functional Signature (GMEFS) based on eight cohorts. The prognostic value of the GMEFS model was also verified in another two glioma cohorts, glioblastoma (GBM) and low-grade glioma (LGG) cohorts, from The Cancer Genome Atlas (TCGA). Nomograms were established in the training and testing cohorts to validate the clinical use of this model. Furthermore, the relationships between the risk score, intrinsic molecular subtypes, tumor purity, and tumor-infiltrating immune cell abundance were also evaluated. Meanwhile, the performance of the GMEFS model in glioma formation and glioma recurrence was systematically analyzed based on 16 glioma cohorts from the Gene Expression Omnibus (GEO) database. Based on multiple-cohort integrated analysis, risk subpathway signatures were identified, and a drug–subpathway association network was further constructed to explore candidate therapy target regions. Three subpathways derived from Focal adhesion (path: 04510) were identified and contained known targets including platelet derived growth factor receptor alpha (PDGFRA), epidermal growth factor receptor (EGFR), and erb-b2 receptor tyrosine kinase 2 (ERBB2). In conclusion, the novel functional signatures identified in this study could serve as a robust prognostic biomarker, and this study provided a framework to identify candidate therapeutic target regions, which further guide glioma patients’ clinical decision.

Endoplasmic Reticulum Stress Contributed to Dipyridamole-Induced Impaired Autophagic Flux and Glioma Apoptosis

Elevation of intracellular cAMP levels has been implicated in glioma cell proliferation inhibition, differentiation, and apoptosis. Inhibition of phosphodiesterase is a way to elevate intracellular cAMP levels. The present study aimed to investigate the anti-glioma potential of dipyridamole, an inhibitor of phosphodiesterase. Upon treatment with dipyridamole, human U87 glioma cells decreased cell viability, clonogenic colonization, migration, and invasion, along with Noxa upregulation, Endoplasmic Reticulum (ER) stress, impaired autophagic flux, Yes-associated Protein 1 (YAP1) phosphorylation, and YAP1 reduction. Pharmacological and genetic studies revealed the ability of dipyridamole to initiate Noxa-guided apoptosis through ER stress. Additionally, the current study further identified the biochemical role of YAP1 in communicating with ER stress and autophagy under situations of dipyridamole treatment. YAP1 promoted autophagy and protected glioma cells from dipyridamole-induced apoptotic cell death. Dipyridamole impaired autophagic flux and rendered glioma cells more vulnerable to apoptotic cell death through ER stress-inhibitable YAP1/autophagy axis. The overall cellular changes caused by dipyridamole appeared to ensure a successful completion of apoptosis. Dipyridamole also duplicated the biochemical changes and apoptosis in glioma T98G cells. Since dipyridamole has additional biochemical and pharmacological properties, further research centered on the anti-glioma mechanisms of dipyridamole is still needed.

[Automated grading of glioma based on density and atypia analysis in whole slide images]

Glioma is the most common malignant brain tumor and classification of low grade glioma (LGG) and high grade glioma (HGG) is an important reference of making decisions on patient treatment options and prognosis. This work is largely done manually by pathologist based on an examination of whole slide image (WSI), which is arduous and heavily dependent on doctors' experience. In the World Health Organization (WHO) criteria, grade of glioma is closely related to hypercellularity, nuclear atypia and necrosis. Inspired by this, this paper designed and extracted cell density and atypia features to classify LGG and HGG. First, regions of interest (ROI) were located by analyzing cell density and global density features were extracted as well. Second, local density and atypia features were extracted in ROI. Third, balanced support vector machine (SVM) classifier was trained and tested using 10 selected features. The area under the curve (AUC) and accuracy (ACC) of 5-fold cross validation were 0.92 ± 0.01 and 0.82 ± 0.01 respectively. The results demonstrate that the proposed method of locating ROI is effective and the designed features of density and atypia can be used to predict glioma grade accurately, which can provide reliable basis for clinical diagnosis.

Preclinical models of glioblastoma: limitations of current models and the promise of new developments

Glioblastoma (GBM) is the most common and aggressive primary brain tumour, yet little progress has been made towards providing better treatment options for patients diagnosed with this devastating condition over the last few decades. The complex nature of the disease, heterogeneity, highly invasive potential of GBM tumours and until recently, reduced investment in research funding compared with other cancer types, are contributing factors to few advancements in disease management. Survival rates remain low with less than 5% of patients surviving 5 years. Another important contributing factor is the use of preclinical models that fail to fully recapitulate GBM pathophysiology, preventing efficient translation from the lab into successful therapies in the clinic. This review critically evaluates current preclinical GBM models, highlighting advantages and disadvantages of using such models, and outlines several emerging techniques in GBM modelling using animal-free approaches. These novel approaches to a highly complex disease such as GBM show evidence of a more truthful recapitulation of GBM pathobiology with high reproducibility. The resulting advancements in this field will offer new biological insights into GBM and its aetiology with potential to contribute towards the development of much needed improved treatments for GBM in future.

Microglial-stimulation of glioma invasion involves the EGFR ligand amphiregulin

High grade glioma is one of the deadliest human cancers with a median survival rate of only one year following diagnosis. The highly motile and invasive nature of high grade glioma makes it difficult to completely remove surgically. Therefore, increasing our knowledge of the mechanisms glioma cells use to invade normal brain is of critical importance in designing novel therapies. It was previously shown by our laboratory that tumor-associated microglia (TAMs) stimulate glioma cell invasion and this process is dependent on CSF-1R signaling. In this study, we seek to identify pro-invasive factors that are upregulated in microglia in a CSF-1R-dependent manner. We assayed cDNA and protein from microglia treated with conditioned media from the murine glioma cell line GL261, and discovered that several EGFR ligands including amphiregulin (AREG) are strongly upregulated. This upregulation is blocked by addition of a pharmacological CSF-1R inhibitor. Using RNA interference, we show that AREG-depleted microglia are less effective at promoting invasion of GL261 cells into Matrigel-coated invasion chambers. In addition, an AREG blocking antibody strongly attenuates the ability of THP-1 macrophages to activate human glioma cell line U87 invasion. Furthermore, we have identified a signaling pathway which involves CSF-1 signaling through ERK to upregulate AREG expression in microglia. Interfering with ERK using pharmacological inhibitors prevents AREG upregulation in microglia and microglia-stimulated GL261 invasion. These data highlight AREG as a key factor in produced by tumor associated microglia in promoting glioma invasion.

The Pivotal Immunomodulatory and Anti-Inflammatory Effect of Histone-Lysine N-Methyltransferase in the Glioma Microenvironment: Its Biomarker and Therapy Potentials

Enhancer of zeste homolog 2 (EZH2) is a histone-lysine N-methyltransferase that encrypts a member of the Polycomb group (PcG) family. EZH2 forms a repressive chromatin structure which eventually participates in regulating the development as well as lineage propagation of stem cells and glioma progression. Posttranslational modifications are distinct approaches for the adjusted modification of EZH2 in the development of cancer. The amino acid succession of EZH2 protein makes it appropriate for covalent modifications, like phosphorylation, acetylation, O-GlcNAcylation, methylation, ubiquitination, and sumoylation. The glioma microenvironment is a dynamic component that comprises, besides glioma cells and glioma stem cells, a complex network that comprises diverse cell types like endothelial cells, astrocytes, and microglia as well as stromal components, soluble factors, and the extracellular membrane. EZH2 is well recognized as an essential modulator of cell invasion as well as metastasis in glioma. EZH2 oversecretion was implicated in the malfunction of several fundamental signaling pathways like Wnt/β-catenin signaling, Ras and NF-κB signaling, PI3K/AKT signaling, β-adrenergic receptor signaling, and bone morphogenetic protein as well as NOTCH signaling pathways. EZH2 was more secreted in glioblastoma multiforme than in low-grade gliomas as well as extremely secreted in U251 and U87 human glioma cells. Thus, the blockade of EZH2 expression in glioma could be of therapeutic value for patients with glioma. The suppression of EZH2 gene secretion was capable of reversing temozolomide resistance in patients with glioma. EZH2 is a promising therapeutic as well as prognostic biomarker for the treatment of glioma.

Intramolecular charge transfer enhancing strategy based MAO-A specific two-photon fluorescent probes for glioma cell/tissue imaging

MAO-A promotes the proliferation of human glioma cells. Herein, we report a series of MAO-A specific two-photon small molecular fluorescent probes (A1-5) based on an intramolecular charge transfer enhancing strategy. The activity of endogenous MAO-A can be selectively imaged using A3 as a representative probe in different biological samples including human glioma cells/tissues via two-photon fluorescence microscopy. The study provides new tools for the visual detection of glioma.

Long-term migratory velocity measurements of single glioma cells using microfluidics

Microfluidic platforms enabling single-cell measurements notably contribute to the identification and observation of rare cancer cells that are involved in tumor invasion. Most aggressive, invasive, and heterogeneous glioblastoma cells cause incurable primary brain tumors. Infiltrating gliomas of a brain tumor microenvironment have been intensively studied using conventional assays. Still, quantitative, simple, and precise tools are required for long-term, steady-state migratory-velocity measurements of single glioma cells. To measure long-term velocity changes and investigate the heterogeneity of glioma cells under different growth conditions, we developed a microfluidic platform. We cultured U87 glioma cells in the microfluidic device using either regular growth medium or conditional medium composed of 50% basal medium and 50% macrophage-depleted medium. We microscopically monitored the behavior of 40 glioma cells for 5 days. Using acquired images, we calculated cellular circularity and determined the migratory velocities of glioma cells from 60 h to 120 h. The mean migratory velocity values of the glioma cells were 1.513 μm h^-1 in the basal medium and 3.246 μm h^-1 in the conditional medium. The circularity values of the glioma cells decreased from 0.20-0.25 to 0.15-0.20 when cultured in the conditional medium. Here, we clearly showed that the glioma cells lost their circularity and increased their steady-state velocities; in other words, they adopted an invasive glioma phenotype in the presence of macrophage-depleted medium. Besides, the heterogeneity of the circularity and the velocity of glioma cells were enhanced in the conditional medium.

RP58 Represses Transcriptional Programs Linked to Nonneuronal Cell Identity and Glioblastoma Subtypes in Developing Neurons

How mammalian neuronal identity is progressively acquired and reinforced during development is not understood. We have previously shown that loss of RP58 (ZNF238 or ZBTB18), a BTB/POZ-zinc finger-containing transcription factor, in the mouse brain leads to microcephaly, corpus callosum agenesis, and cerebellum hypoplasia and that it is required for normal neuronal differentiation. The transcriptional programs regulated by RP58 during this process are not known. Here, we report for the first time that in embryonic mouse neocortical neurons a complex set of genes normally expressed in other cell types, such as those from mesoderm derivatives, must be actively repressed in vivo and that RP58 is a critical regulator of these repressed transcriptional programs. Importantly, gene set enrichment analysis (GSEA) analyses of these transcriptional programs indicate that repressed genes include distinct sets of genes significantly associated with glioma progression and/or pluripotency. We also demonstrate that reintroducing RP58 in glioma stem cells leads not only to aspects of neuronal differentiation but also to loss of stem cell characteristics, including loss of stem cell markers and decrease in stem cell self-renewal capacities. Thus, RP58 acts as an in vivo master guardian of the neuronal identity transcriptome, and its function may be required to prevent brain disease development, including glioma progression.

A short review on cross-link between pyruvate kinase (PKM2) and Glioblastoma Multiforme

Pyruvate kinase (PK) catalyzes the last irreversible reaction of glycolysis pathway, generating pyruvate and ATP, from Phosphoenol Pyruvate (PEP) and ADP precursors. In mammals, four different tissue-specific isoforms (M1, M2, L and R) of PK exist, which are translated from two genes (PKL and PKR). PKM2 is the highly expressed isoform of PK in cancers, which regulates the aerobic glycolysis via reprogramming cancer cell's metabolic pathways to provide an anabolic advantage to the tumor cells. In addition to the established role of PKM2 in aerobic glycolysis of multiple cancer types, various recent findings have highlighted the non-metabolic functions of PKM2 in brain tumor development. Nuclear PKM2 acts as a co-activator and directly regulates gene transcription. PKM2 dependent transactivation of various oncogenic genes is instrumental in the progression and aggressiveness of Glioblastoma Multiforme (GBM). Also, PKM2 acts as a protein kinase in histone modification which regulates gene expression and tumorigenesis. Ongoing research has explored novel regulatory mechanisms of PKM2 and its association in GBM progression. This review enlists and summarizes the metabolic and non-metabolic roles of PKM2 at the cellular level, and its regulatory function highlights the importance of the nuclear functions of PKM2 in GBM progression, and an emerging role of PKM2 as novel cancer therapeutics.

Circular RNA circ_0001162 promotes cell proliferation and invasion of glioma via the miR-936/ERBB4 axis

The biological modulatory roles of many circular RNAs (circRNAs) have been validated in glioma. The current study was designed to research the functional mechanism of circ_0001162 in glioma progression. The quantitative real-time polymerase chain reaction (qRT-PCR) was used for assaying the levels of circ_0001162 and microRNA-936 (miR-936). Cell proliferation and colony formation abilities were evaluated via 3-(4, 5-dimethylthiazol-2-y1)-2, 5-diphenyl tetrazolium bromide (MTT) and colony formation assay, respectively. Transwell assay was applied to assess cell migration and invasion. The impact of circ_0001162 on glioma growth in vivo was performed using xenograft tumor assay. The target binding was affirmed via the dual-luciferase reporter and RNA pull-down assays. All protein expression levels were examined via Western blot. Circ_0001162 was an overexpressed circRNA in glioma. Circ_0001162 promoted glioma cell proliferation, colony formation, migration and invasion in vitro. Tumorigenesis of glioma in vivo was also enhanced by circ_0001162. Circ_0001162 could directly target miR-936 and the biological function of circ_0001162 in glioma was related to the inhibition of miR-936. ErbB2 receptor tyrosine kinase 4 (ERBB4) was a direct target of miR-936. Additionally, miR-936 inhibited the glioma development via targeting ERBB4. The miR-936/ERBB4 axis was responsible for the oncogenic role of circ_0001162 in glioma. The effects of circ_0001162 on glioma cells were also associated with the positive regulation of ERBB4. These results indicated that circ_0001162 contributed to the glioma progression via regulating the miR-936/ERBB4 axis, which laid a foundation for the pathomechanism and molecular treatment of glioma.

Opposed Interplay between IDH1 Mutations and the WNT/β-Catenin Pathway: Added Information for Glioma Classification

Gliomas are the main common primary intraparenchymal brain tumor in the central nervous system (CNS), with approximately 7% of the death caused by cancers. In the WHO 2016 classification, molecular dysregulations are part of the definition of particular brain tumor entities for the first time. Nevertheless, the underlying molecular mechanisms remain unclear. Several studies have shown that 75% to 80% of secondary glioblastoma (GBM) showed IDH1 mutations, whereas only 5% of primary GBM have IDH1 mutations. IDH1 mutations lead to better overall survival in gliomas patients. IDH1 mutations are associated with lower stimulation of the HIF-1α a, aerobic glycolysis and angiogenesis. The stimulation of HIF-1α and the process of angiogenesis appears to be activated only when hypoxia occurs in IDH1-mutated gliomas. In contrast, the observed upregulation of the canonical WNT/β-catenin pathway in gliomas is associated with proliferation, invasion, aggressive-ness and angiogenesis.. Molecular pathways of the malignancy process are involved in early stages of WNT/β-catenin pathway-activated-gliomas, and this even under normoxic conditions. IDH1 mutations lead to decreased activity of the WNT/β-catenin pathway and its enzymatic targets. The opposed interplay between IDH1 mutations and the canonical WNT/β-catenin pathway in gliomas could participate in better understanding of the observed evolution of different tumors and could reinforce the glioma classification.

Anti-Tumor Functions of Prelatent Antithrombin on Glioblastoma Multiforme Cells

Antithrombin, the main physiological inhibitor of the coagulation cascade, exerts anti-tumor effects on glioblastoma multiforme cells. Antithrombin has different conformations: native, heparin-activated, prelatent, latent, and cleaved. The prelatent form has an intermediate affinity between latent and native antithrombin, although it is the most antiangiogenic form. Herein, we investigate the effect of this conformation on the tumorigenic processes of glioblastoma multiforme cells. Antithrombin forms were purified by chromatography. Chromogenic/fluorogenic assays were carried out to evaluate enteropeptidase and hepsin inhibition, two serine proteases involved in these processes. Wound healing, Matrigel invasion and BrdU incorporation assays were performed to study migration, invasion and proliferation. E-cadherin, Vimentin, VEGFA, pAKT, STAT3, pSTAT3, and pERK1/2 expression was assessed by Western blot and/or qRT-PCR. Prelatent antithrombin inhibited both enteropeptidase and hepsin, although it was less efficient than the native conformation. Exposure to prelatent antithrombin significantly reduced migration and invasion but not proliferation of U-87 MG, being the conformation most efficient on migration. Prelatent antithrombin down-regulated VEGFA, pSTAT3, and pERK1/2 expression in U-87 MG cells. Our work elucidates that prelatent antithrombin has surprisingly versatile anti-tumor properties in U-87 MG glioblastoma multiforme cells. This associates with resistance pathway activation, the decreased expression of tumorigenic proteins, and increased angiogenesis, postulating the existence of a new, formerly unknown receptor with potential therapeutic implications.

Assessment of variation of inline cartridge extraction mass spectra

Recently, mass-spectrometry methods show its utility in tumor boundary location. The effect of differences between research and clinical protocols such as low- and high-resolution measurements and sample storage have to be understood and taken into account to transfer methods from bench to bedside. In this study, we demonstrate a simple way to compare mass spectra obtained by different experimental protocols, assess its quality, and check for the presence of outliers and batch effect in the dataset. We compare the mass spectra of both fresh and frozen-thawed astrocytic brain tumor samples obtained with the inline cartridge extraction prior to electrospray ionization. Our results reveal the importance of both positive and negative ion mode mass spectrometry for getting reliable information about sample diversity. We show that positive mode highlights the difference between protocols of mass spectra measurement, such as fresh and frozen-thawed samples, whereas negative mode better characterizes the histological difference between samples. We also show how the use of similarity spectrum matrix helps to identify the proper choice of the measurement parameters, so data collection would be kept reliable, and analysis would be correct and meaningful.

Genetic and expression variations of cell cycle pathway genes in brain tumor patients

The present study was designed to determine the association between the genetic polymorphisms/expression variations of RB1 and CCND1 genes and brain tumor risk. For this purpose, 250 blood samples of brain tumor patients along with 250 controls (cohort I) and 96 brain tumor tissues (cohort II) with adjacent control section were collected. Mutation analysis of RB1 (rs137853294, rs121913300) and CCND1 (rs614367, rs498136) genes was performed using ARMS-PCR followed by sequencing, and expression analysis was performed using real-time PCR and immunohistochemistry. The results showed homozygous mutant genotype of RB1 gene polymorphism, rs121913300 (P=0.003) and CCND1 gene polymorphism rs614367 (P=0.01) were associated significantly with brain tumor risk. Moreover, significant down-regulation of RB1 (P=0.005) and up-regulation of CCND1 (P=0.0001) gene was observed in brain tumor sections vs controls. Spearman correlation showed significant negative correlation between RB1 vs proliferation marker, Ki-67 (r = -0.291*, P<0.05) in brain tumors. Expression levels of selected genes were also assessed at protein level using immunohistochemical analysis (IHC) and signification down-regulation of RB1 (P=0.0001) and up-regulation of CCND1 (P=0.0001) was observed in brain tumor compared with control sections. In conclusion, it is suggested that polymorphisms/expression variations of RB1 and CCND1 genes may be associated with increased risk of brain tumor.

Stepwise crosstalk between aberrant Nf1, Tp53 and Rb signalling pathways induces gliomagenesis in zebrafish

The molecular pathogenesis of glioblastoma indicates that RTK/Ras/PI3K, RB and TP53 pathways are critical for human gliomagenesis. Here, several transgenic zebrafish lines with single or multiple deletions of nf1, tp53 and rb1 in astrocytes, were established to genetically induce gliomagenesis in zebrafish. In the mutant with a single deletion, we found only the nf1 mutation low-efficiently induced tumour incidence, suggesting that the Nf1 pathway is critical for the initiation of gliomagenesis in zebrafish. Combination of mutations, nf1;tp53 and rb1;tp53 combined knockout fish, showed much higher tumour incidences, high-grade histology, increased invasiveness, and shortened survival time. Further bioinformatics analyses demonstrated the alterations in RTK/Ras/PI3K, cell cycle, and focal adhesion pathways, induced by abrogated nf1, tp53, or rb1, were probably the critical stepwise biological events for the initiation and development of gliomagenesis in zebrafish. Gene expression profiling and histological analyses showed the tumours derived from zebrafish have significant similarities to the subgroups of human gliomas. Furthermore, temozolomide treatment effectively suppressed gliomagenesis in these glioma zebrafish models, and the histological responses in temozolomide-treated zebrafish were similar to those observed in clinically treated glioma patients. Thus, our findings will offer a potential tool for genetically investigating gliomagenesis and screening potential targeted anti-tumour compounds for glioma treatment.

The nuclear transporter importin-11 regulates the Wnt/β-catenin pathway and acts as a tumor promoter in glioma

Karyopherins mediate the macromolecular transport between the cytoplasm and the nucleus and participate in cancer progression. However, the role and mechanism of importin-11 (IPO11), a member of the karyopherin family, in glioma progression remain undefined. Effects of IPO11 on glioma progression were detected using CCK-8, colony formation assay, flow cytometry analysis, caspase-3 activity assay, and Transwell invasion assay. Western blot analysis was used to detect the expression of active caspase-3, active caspase-7, active caspase-9, N-cadherin, Vimentin, E-cadherin, β-catenin, and c-Myc. The activity of Wnt/β-catenin pathway was evaluated by the T-cell factor/lymphoid enhancer factor (TCF/LEF) transcription factor reporter assay. Results showed that IPO11 knockdown inhibited proliferation and reduced colony number in glioma cells. IPO11 silencing promoted the apoptotic rate, increased expression levels of active caspase-3, caspase-7, and caspase-9, and enhanced caspase-3 activity. Moreover, IPO11 silencing inhibited glioma cell invasion by suppressing epithelial-to-mesenchymal transition (EMT). Mechanistically, IPO11 knockdown inactivated the Wnt/β-catenin pathway. β-Catenin overexpression abolished the effects of IPO11 silencing on the proliferation, apoptosis, and invasion in glioma cells. Furthermore, IPO11 silencing blocked the malignant phenotypes and repressed the Wnt/β-catenin pathway in vivo. In conclusion, IPO11 knockdown suppressed the malignant phenotypes of glioma cells by inactivating the Wnt/β-catenin pathway.