Tumor Cell Invasion in Glioblastoma

In Vitro and In Vivo Drug-Response Profiling Using Patient-Derived High-Grade Glioma

BACKGROUND

Genomic profiling cannot solely predict the complexity of how tumor cells behave in their in vivo microenvironment and their susceptibility to therapies. The aim of the study was to establish a functional drug prediction model utilizing patient-derived GBM tumor samples for in vitro testing of drug efficacy followed by in vivo validation to overcome the disadvantages of a strict pharmacogenomics approach.

METHODS

High-throughput in vitro pharmacologic testing of patient-derived GBM tumors cultured as 3D organoids offered a cost-effective, clinically and phenotypically relevant model, inclusive of tumor plasticity and stroma. RNAseq analysis supplemented this 128-compound screening to predict more efficacious and patient-specific drug combinations with additional tumor stemness evaluated using flow cytometry. In vivo PDX mouse models rapidly validated (50 days) and determined mutational influence alongside of drug efficacy. We present a representative GBM case of three tumors resected at initial presentation, at first recurrence without any treatment, and at a second recurrence following radiation and chemotherapy, all from the same patient.

RESULTS

Molecular and in vitro screening helped identify effective drug targets against several pathways as well as synergistic drug combinations of cobimetinib and vemurafenib for this patient, supported in part by in vivo tumor growth assessment. Each tumor iteration showed significantly varying stemness and drug resistance.

CONCLUSIONS

Our integrative model utilizing molecular, in vitro, and in vivo approaches provides direct evidence of a patient's tumor response drifting with treatment and time, as demonstrated by dynamic changes in their tumor profile, which may affect how one would address that drift pharmacologically.

Regulation of EMT Markers, Extracellular Matrix, and Associated Signalling Pathways by Long Non-Coding RNAs in Glioblastoma Mesenchymal Transition: A Scoping Review

Glioblastoma (GBM) mesenchymal (MES) transition can be regulated by long non-coding RNAs (lncRNAs) via modulation of various factors (Epithelial-to-Mesenchymal (EMT) markers, biological signalling, and the extracellular matrix (ECM)). However, understanding of these mechanisms in terms of lncRNAs is largely sparse. This review systematically analysed the mechanisms by which lncRNAs influence MES transition in GBM from a systematic search of the literature (using PRISMA) performed in five databases (PubMed, MEDLINE, EMBASE, Scopus, and Web of Science). We identified a total of 62 lncRNAs affiliated with GBM MES transition, of which 52 were upregulated and 10 were downregulated in GBM cells, where 55 lncRNAs were identified to regulate classical EMT markers in GBM (E-cadherin, N-cadherin, and vimentin) and 25 lncRNAs were reported to regulate EMT transcription factors (ZEB1, Snai1, Slug, Twist, and Notch); a total of 16 lncRNAs were found to regulate the associated signalling pathways (Wnt/β-catenin, PI3k/Akt/mTOR, TGFβ, and NF-κB) and 14 lncRNAs were reported to regulate ECM components (MMP2/9, fibronectin, CD44, and integrin-β1). A total of 25 lncRNAs were found dysregulated in clinical samples (TCGA vs. GTEx), of which 17 were upregulated and 8 were downregulated. Gene set enrichment analysis predicted the functions of HOXAS3, H19, HOTTIP, MEG3, DGCR5, and XIST at the transcriptional and translational levels based on their interacting target proteins. Our analysis observed that the MES transition is regulated by complex interplays between the signalling pathways and EMT factors. Nevertheless, further empirical studies are required to elucidate the complexity in this process between these EMT factors and the signalling involved in the GBM MES transition.

Repurposing FDA-approved drugs as inhibitors of therapy-induced invadopodia activity in glioblastoma cells

Glioblastoma (GBM) is the most prevalent primary central nervous system tumour in adults. The lethality of GBM lies in its highly invasive, infiltrative, and neurologically destructive nature resulting in treatment failure, tumour recurrence and death. Even with current standard of care treatment with surgery, radiotherapy and chemotherapy, surviving tumour cells invade throughout the brain. We have previously shown that this invasive phenotype is facilitated by actin-rich, membrane-based structures known as invadopodia. The formation and matrix degrading activity of invadopodia is enhanced in GBM cells that survive treatment. Drug repurposing provides a means of identifying new therapeutic applications for existing drugs without the need for discovery or development and the associated time for clinical implementation. We investigate several FDA-approved agents for their ability to act as both cytotoxic agents in reducing cell viability and as 'anti-invadopodia' agents in GBM cell lines. Based on their cytotoxicity profile, three agents were selected, bortezomib, everolimus and fludarabine, to test their effect on GBM cell invasion. All three drugs reduced radiation/temozolomide-induced invadopodia activity, in addition to reducing GBM cell viability. These drugs demonstrate efficacious properties warranting further investigation with the potential to be implemented as part of the treatment regime for GBM.

HDAC1 mediates epithelial-mesenchymal transition and promotes cancer cell invasion in glioblastoma

Glioblastoma multiforme (GBM) is one of the most malignant tumors of the central nervous system, and its treatment has always been a difficult clinical problem. Here, we evaluated HDAC1 expression patterns and their effect on prognosis based on GBM cases from TCGA and CGGA databases. Expression was compared between GBM samples and normal controls. High HDAC1 expression was found to be an indicator of poor prognosis in glioblastoma. We also established a protein-protein interaction network to explore HDAC1-related interacting proteins, including the epithelial-mesenchymal transition (EMT)-related protein VIM, which is closely associated with HDAC1. Consistently, functional enrichment analysis showed that several GBM tissues with high HDAC1 were enriched in the expression of cancer markers, such as those involved in glycolysis, hypoxia, inflammation, and some signaling pathways. Next, this study analyzed the effect of HDAC1 on invasive ability and the EMT signaling pathway in GBM cells in vitro. The results showed that an HDAC1 inhibitor (RGFP109) could inhibit the EMT process in glioma cells in vitro, thereby affecting the invasion and migration of cells. Similar results were obtained based on in vivo studies. Our data suggest that HDAC1 has the potential to be a powerful prognostic biomarker, which might provide a basis for developing therapeutic targets for GBM.

Glycation Leads to Increased Invasion of Glioblastoma Cells

Glioblastoma (GBM) is a highly aggressive and invasive brain tumor with a poor prognosis despite extensive treatment. The switch to aerobic glycolysis, known as the Warburg effect, in cancer cells leads to an increased production of methylglyoxal (MGO), a potent glycation agent with pro-tumorigenic characteristics. MGO non-enzymatically reacts with proteins, DNA, and lipids, leading to alterations in the signaling pathways, genomic instability, and cellular dysfunction. In this study, we investigated the impact of MGO on the LN229 and U251 (WHO grade IV, GBM) cell lines and the U343 (WHO grade III) glioma cell line, along with primary human astrocytes (hA). The results showed that increasing concentrations of MGO led to glycation, the accumulation of advanced glycation end-products, and decreasing cell viability in all cell lines. The invasiveness of the GBM cell lines increased under the influence of physiological MGO concentrations (0.3 mmol/L), resulting in a more aggressive phenotype, whereas glycation decreased the invasion potential of hA. In addition, glycation had differential effects on the ECM components that are involved in the invasion progress, upregulating TGFβ, brevican, and tenascin C in the GBM cell lines LN229 and U251. These findings highlight the importance of further studies on the prevention of glycation through MGO scavengers or glyoxalase 1 activators as a potential therapeutic strategy against glioma and GBM.

Characterizing the function-related specific assembly pattern of matrix metalloproteinase-14 by dSTORM imaging

As transmembrane proteolytic enzyme, matrix metalloproteinase-14 (MMP14) regulates cell migration and cancer metastasis, but how it works at the single molecule level is unclear. Molecular localization is closely related to its function, and revealing its spatial assemble details is thus helpful to understand bio-function. Here, we apply aptamer probe and dSTORM to characterize MMP14 distribution. With demonstrating labeling properties of the probe, we investigate the specific distributed pattern of MMP14 on various cell membranes with different migratory capacities, and find that MMP14 mostly aggregate in clustering state, which becomes more significant with enhancing its hydrolysis efficiency on high-migratory cells. Lots of MMP14 are revealed to be co-localized with its substrate PTK7, and this colocalization decreases with weakening cell migration, suggesting that MMP14 may coordinate cell migration by altering its spatial relationship with substrate proteins. This work will promote a deep understanding of the roles of MMP14 in cell migration and cancer metastasis.

Is pre-radiotherapy metabolic heterogeneity of glioblastoma predictive of progression-free survival?

BACKGROUND AND PURPOSE

All glioblastoma subtypes share the hallmark of aggressive invasion, meaning that it is crucial to identify their different components if we are to ensure effective treatment and improve survival. Proton MR spectroscopic imaging (MRSI) is a noninvasive technique that yields metabolic information and is able to identify pathological tissue with high accuracy. The aim of the present study was to identify clusters of metabolic heterogeneity, using a large MRSI dataset, and determine which of these clusters are predictive of progression-free survival (PFS).

MATERIALS AND METHODS

MRSI data of 180 patients acquired in a pre-radiotherapy examination were included in the prospective SPECTRO-GLIO trial. Eight features were extracted for each spectrum: Cho/NAA, NAA/Cr, Cho/Cr, Lac/NAA, and the ratio of each metabolite to the sum of all the metabolites. Clustering of data was performed using a mini-batch k-means algorithm. The Cox model and logrank test were used for PFS analysis.

RESULTS

Five clusters were identified as sharing similar metabolic information and being predictive of PFS. Two clusters revealed metabolic abnormalities. PFS was lower when Cluster 2 was the dominant cluster in patients' MRSI data. Among the metabolites, lactate (present in this cluster and in Cluster 5) was the most statistically significant predictor of poor outcome.

CONCLUSION

Results showed that pre-radiotherapy MRSI can be used to reveal tumor heterogeneity. Groups of spectra, which have the same metabolic information, reflect the different tissue components representative of tumor burden proliferation and hypoxia. Clusters with metabolic abnormalities and high lactate are predictive of PFS.

Exploring Monocytes-Macrophages in Immune Microenvironment of Glioblastoma for the Design of Novel Therapeutic Strategies

Gliomas are primary malignant brain tumors. These tumors seem to be more and more frequent, not only because of a true increase in their incidence, but also due to the increase in life expectancy of the general population. Among gliomas, malignant gliomas and more specifically glioblastomas (GBM) are a challenge in their diagnosis and treatment. There are few effective therapies for these tumors, and patients with GBM fare poorly, even after aggressive surgery, chemotherapy, and radiation. Over the last decade, it is now appreciated that these tumors are composed of numerous distinct tumoral and non-tumoral cell populations, which could each influence the overall tumor biology and response to therapies. Monocytes have been proved to actively participate in tumor growth, giving rise to the support of tumor-associated macrophages (TAMs). In GBM, TAMs represent up to one half of the tumor mass cells, including both infiltrating macrophages and resident brain microglia. Infiltrating macrophages/monocytes constituted ~ 85% of the total TAM population, they have immune functions, and they can release a wide array of growth factors and cytokines in response to those factors produced by tumor and non-tumor cells from the tumor microenvironment (TME). A brief review of the literature shows that this cell population has been increasingly studied in GBM TME to understand its role in tumor progression and therapeutic resistance. Through the knowledge of its biology and protumoral function, the development of therapeutic strategies that employ their recruitment as well as the modulation of their immunological phenotype, and even the eradication of the cell population, can be harnessed for therapeutic benefit. This revision aims to summarize GBM TME and localization in tumor niches with special focus on TAM population, its origin and functions in tumor progression and resistance to conventional and experimental GBM treatments. Moreover, recent advances on the development of TAM cell targeting and new cellular therapeutic strategies based on monocyte/macrophages recruitment to eradicate GBM are discussed as complementary therapeutics.

Remote neuronal activity drives glioma infiltration via Sema4f

The tumor microenvironment (TME) plays an essential role in malignancy and neurons have emerged as a key component of the TME that promotes tumorigenesis across a host of cancers. Recent studies on glioblastoma (GBM) highlight bi-directional signaling between tumors and neurons that propagates a vicious cycle of proliferation, synaptic integration, and brain hyperactivity; however, the identity of neuronal subtypes and tumor subpopulations driving this phenomenon are incompletely understood. Here we show that callosal projection neurons located in the hemisphere contralateral to primary GBM tumors promote progression and widespread infiltration. Using this platform to examine GBM infiltration, we identified an activity dependent infiltrating population present at the leading edge of mouse and human tumors that is enriched for axon guidance genes. High-throughput, in vivo screening of these genes identified Sema4F as a key regulator of tumorigenesis and activity-dependent infiltration. Furthermore, Sema4F promotes the activity-dependent infiltrating population and propagates bi-directional signaling with neurons by remodeling tumor adjacent synapses towards brain network hyperactivity. Collectively, our studies demonstrate that subsets of neurons in locations remote to primary GBM promote malignant progression, while revealing new mechanisms of tumor infiltration that are regulated by neuronal activity.

Cross-platform analysis reveals cellular and molecular landscape of glioblastoma invasion

BACKGROUND

Improved treatment of glioblastoma (GBM) needs to address tumor invasion, a hallmark of the disease that remains poorly understood. In this study, we profiled GBM invasion through integrative analysis of histological and single-cell RNA sequencing (scRNA-seq) data from 10 patients.

METHODS

Human histology samples, patient-derived xenograft mouse histology samples, and scRNA-seq data were collected from 10 GBM patients. Tumor invasion was characterized and quantified at the phenotypic level using hematoxylin and eosin and Ki-67 histology stains. Crystallin alpha B (CRYAB) and CD44 were identified as regulators of tumor invasion from scRNA-seq transcriptomic data and validated in vitro, in vivo, and in a mouse GBM resection model.

RESULTS

At the cellular level, we found that invasive GBM are less dense and proliferative than their non-invasive counterparts. At the molecular level, we identified unique transcriptomic features that significantly contribute to GBM invasion. Specifically, we found that CRYAB significantly contributes to postoperative recurrence and is highly co-expressed with CD44 in invasive GBM samples.

CONCLUSIONS

Collectively, our analysis identifies differentially expressed features between invasive and nodular GBM, and describes a novel relationship between CRYAB and CD44 that contributes to tumor invasiveness, establishing a cellular and molecular landscape of GBM invasion.

Bioconjugation of COL1 protein on liquid-like solid surfaces to study tumor invasion dynamics

Tumor invasion is likely driven by the product of intrinsic and extrinsic stresses, reduced intercellular adhesion, and reciprocal interactions between the cancer cells and the extracellular matrix (ECM). The ECM is a dynamic material system that is continuously evolving with the tumor microenvironment. Although it is widely reported that cancer cells degrade the ECM to create paths for migration using membrane-bound and soluble enzymes, other nonenzymatic mechanisms of invasion are less studied and not clearly understood. To explore tumor invasion that is independent of enzymatic degradation, we have created an open three-dimensional (3D) microchannel network using a novel bioconjugated liquid-like solid (LLS) medium to mimic both the tortuosity and the permeability of a loose capillary-like network. The LLS is made from an ensemble of soft granular microgels, which provides an accessible platform to investigate the 3D invasion of glioblastoma (GBM) tumor spheroids using in situ scanning confocal microscopy. The surface conjugation of the LLS microgels with type 1 collagen (COL1-LLS) enables cell adhesion and migration. In this model, invasive fronts of the GBM microtumor protruded into the proximal interstitial space and may have locally reorganized the surrounding COL1-LLS. Characterization of the invasive paths revealed a super-diffusive behavior of these fronts. Numerical simulations suggest that the interstitial space guided tumor invasion by restricting available paths, and this physical restriction is responsible for the super-diffusive behavior. This study also presents evidence that cancer cells utilize anchorage-dependent migration to explore their surroundings, and geometrical cues guide 3D tumor invasion along the accessible paths independent of proteolytic ability.

3D models of glioblastoma interaction with cortical cells

Introduction: Glioblastoma (GBM) invasiveness and ability to infiltrate deep into the brain tissue is a major reason for the poor patient prognosis for this type of brain cancer. Behavior of glioblastoma cells, including their motility, and expression of invasion-promoting genes such as matrix metalloprotease-2 (MMP2), are strongly influenced by normal cells found in the brain parenchyma. Cells such as neurons may also be influenced by the tumor, as many glioblastoma patients develop epilepsy. In vitro models of glioblastoma invasiveness are used to supplement animal models in a search for better treatments, and need to combine capability for high-throughput experiments with capturing bidirectional interactions between GBM and brain cells.

Methods: In this work, two 3D in vitro models of GBM-cortical interactions were investigated. A matrix-free model was created by co-culturing GBM and cortical spheroids, and a matrix-based model was created by embedding cortical cells and a GBM spheroid in Matrigel.

Results: Rapid GBM invasion occurred in the matrix-based model, and was enhanced by the presence of cortical cells. Little invasion occurred in the matrix-free model. In both types of models, presence of GBM cells resulted in a significant increase in paroxysmal neuronal activity.

Discussion: Matrix-based model may be better suited for studying GBM invasion in an environment that includes cortical cells, while matrix-free model may be useful in investigation of tumor-associated epilepsy.

Genome-wide methylation analysis of circulating tumor DNA: A new biomarker for recurrent glioblastom

Background

Glioblastoma (GBM) is a malignant tumor with a short survival and poor prognosis and a lack of clinically validated biomarkers for diagnosis and prognosis.

Methods

We collected cerebrospinal fluid (CSF) samples and normal CSF sample from recurrent GBM patients and paired tissue samples. Methylation profiles of CSF circulating tumor DNA (ctDNA) and transcriptional profiles of tumor tissues were analyzed. The China Glioma Genome Atlas (CGGA) database and Gene Expression Omnibus (GEO) was used for data analysis.

Results

Lasso analysis and multiplex Cox analysis were performed using intersecting genes of differentially methylated regions and differentially expressed genes. 8 hub genes were screened to construct diagnostic and prognostic models. Based on these 8 hub genes, the diagnostic (AUC = 0.944) and prognostic (3-years, AUC = 0.876) models were accurate.

Conclusions

In this study, 8 hub genes were identified for the diagnosis and prognosis of recurrent GBM, providing new biomarkers for the clinical study of recurrent GBM.

Oncolytic HSV-1 suppresses cell invasion through downregulating Sp1 in experimental glioblastoma

Gliomas are highly aggressive intracranial tumors that are difficult to resect and have high lethality and recurrence rates. According to WHO grading criteria, glioblastoma with wild-type IDH1 has a poorer prognosis than WHO grade 4 IDH-mutant astrocytomas. To date, no effective therapeutic strategies have been developed to treat glioblastoma. Clinical trials have shown that herpes simplex virus (HSV)-1 is the safest and most efficacious oncolytic virus against glioblastoma, but the molecular antitumor mechanism of action of HSV-1 has not yet been determined. Deletion of the γ34.5 and ICP47 genes from a strain of HSV-1 yielded the oncolytic virus, oHSV-1, which reduced glioma cell viability, migration, and invasive capacity, as well as the growth of microvilli. Infected cell polypeptide 4 (ICP4) expressed by oHSV-1 was found to suppress the expression of the transcription factor Sp1, reducing the expression of host invasion-related genes. In vivo, oHSV-1 showed significant antitumor effects by suppressing the expression of Sp1 and invasion-associated genes, highly expressed in high-grade glioblastoma tissue specimens. These findings indicate that Sp1 may be a molecular marker predicting the antitumor effects of oHSV-1 in the treatment of glioma and that oHSV-1 suppresses host cell invasion through the ICP4-mediated downregulation of Sp1.

Purinergic approach to effective glioma treatment with temozolomide reveals enhanced anti-cancer effects mediated by P2X7 receptor

The purinergic signaling pathway is the oldest evolutionary transmitter system that regulates a wide array of physiological and pathophysiological processes in central nervous system. However, the question of how the purinergic compounds interact with administrated drugs is rarely addressed. We aimed to clarify the interplay between purinergic signaling and chemotherapeutic drug temozolomide (TMZ) in human glioma cell line. We applied an initial retinoic acid-induced differentiation of A172 glioma cells and tested the P2X7 receptor expression in undifferentiated and differentiated gliomas. We compared the P2X7 receptor agonists/antagonists influence and their co-action with TMZ in both cell types through assessment of cell proliferation, viability and migrative properties. Molecular docking allowed to indicate the potential binding site for TMZ in the structure of hP2X7 receptor. Differentiated cells turned out to be more susceptible to ATP and TMZ alone but also to the concerted action of TMZ and ATP. Enhanced effects triggered by ATP and TMZ treatment include the decreased by 70% viability, and reduced migration ability of differentiated A172 glioma cells. Noteworthy, these results can be achieved already at low non-toxic ATP concentration and at reduced to 125 μM effective concentration of TMZ. Therefore, ATP molecules must be present and maintained at appropriate concentration in glioma cells microenvironment to achieve their co-action with TMZ and enhanced anti-cancer activity. All that, in turn, could shorten the therapy, increase its efficacy and limit the side effects for the patient. Our purinergic approach creates a promising perspective for developing novel combined oncological therapies.

Single-Cell Analysis of Unidirectional Migration of Glioblastoma Cells Using a Fiber-Based Scaffold

Glioblastoma (GBM) is a malignant incurable brain tumor in which immature neoplastic cells infiltrate brain tissue by spreading along nerve fibers. The aim of the study was to compare the migration abilities of glioma cells with those of other cancer cells and elucidate the migratory profiles underlying the differential migration of glioma cells using a fiber-based quantitative migration assay. Here, wound healing and transwell assays were used to assess cell mobility in four cell lines: U87-MG glioblastoma cells, MDA-MB-231 breast cancer cells, HCT116 colorectal cancer cells, and MKN45 gastric cancer cells. We also assessed cell mobility using a fiber model that mimics nerve fibers. Time-lapse video microscopy was used to observe cell migration and morphology. The cytoskeleton arrangement was assessed in the fiber model and compared with that in the conventional cell culture model. The conventional evaluation of cell migration ability revealed that the migration ability of breast cancer and glioblastoma cell lines was higher than that of colon cancer and gastric cancer cell lines. The fiber model confirmed that the glioblastoma cell line had a significantly higher migration ability than other cell lines. Tubulin levels were significantly higher in the glioblastoma cells than in other cell lines. In conclusion, the developed fiber-based culture model revealed the specific migratory profile of GBM cells during invasion.

Identification of Dysregulated microRNAs in Glioblastoma Stem-like Cells

Glioblastoma multiforme (GBM) is the most common malignant primary brain tumor in adults. Despite multimodal therapy, median survival is poor at 12-15 months. At the molecular level, radio-/chemoresistance and resulting tumor progression are attributed to a small fraction of tumor cells, termed glioblastoma stem-like cells (GSCs). These CD133-expressing, self-renewing cells display the properties of multi-lineage differentiation, resulting in the heterogenous composition of GBM. MicroRNAs (miRNAs) as regulators of gene expression at the post-transcriptional level can alter many pathways pivotal to cancer stem cell fate. This study explored changes in the miRNA expression profiles in patient-derived GSCs altered on differentiation into glial fiber acid protein (GFAP)-expressing, astrocytic tumor cells using a polymerase chain reaction (PCR) array. Initially, 22 miRNAs showed higher expression in GSCs and 9 miRNAs in differentiated cells. The two most downregulated miRNAs in differentiated GSCs were miR-17-5p and miR-425-5p, whilst the most upregulated miRNAs were miR-223-3p and let-7-5p. Among those, miR-425-5p showed the highest consistency in an upregulation in all three GSCs. By transfection of a 425-5p miRNA mimic, we demonstrated downregulation of the GFAP protein in differentiated patient-derived GBM cells, providing potential evidence for direct regulation of miRNAs in the GSC/GBM cell transition.

Development and validation of an advanced ex vivo brain slice invasion assay to model glioblastoma cell invasion into the complex brain microenvironment

Organotypic cultures of murine brain slices are well-established tools in neuroscience research, including electrophysiology studies, modeling neurodegeneration, and cancer research. Here, we present an optimized ex vivo brain slice invasion assay that models glioblastoma multiforme (GBM) cell invasion into organotypic brain slices. Using this model, human GBM spheroids can be implanted with precision onto murine brain slices and cultured ex vivo to allow tumour cell invasion into the brain tissue. Traditional top-down confocal microscopy allows for imaging of GBM cell migration along the top of the brain slice, but there is limited resolution of tumour cell invasion into the slice. Our novel imaging and quantification technique involves embedding stained brain slices into an agar block, re-sectioning the slice in the Z-direction onto slides, and then using confocal microscopy to image cellular invasion into the brain tissue. This imaging technique allows for the visualization of invasive structures beneath the spheroid that would otherwise go undetected using traditional microscopy approaches. Our ImageJ macro (BraInZ) allows for the quantification of GBM brain slice invasion in the Z-direction. Importantly, we note striking differences in the modes of motility observed when GBM cells invade into Matrigel in vitro versus into brain tissue ex vivo highlighting the importance of incorporating the brain microenvironment when studying GBM invasion. In summary, our version of the ex vivo brain slice invasion assay improves upon previously published models by more clearly differentiating between migration along the top of the brain slice versus invasion into the slice.

Biological Evaluation and In Vitro Characterization of ADME Profile of In-House Pyrazolo[3,4-d]pyrimidines as Dual Tyrosine Kinase Inhibitors Active against Glioblastoma Multiforme

The therapeutic use of tyrosine kinase inhibitors (TKIs) represents one of the successful strategies for the treatment of glioblastoma (GBM). Pyrazolo[3,4-d]pyrimidines have already been reported as promising small molecules active as c-Src/Abl dual inhibitors. Herein, we present a series of pyrazolo[3,4-d]pyrimidine derivatives, selected from our in-house library, to identify a promising candidate active against GBM. The inhibitory activity against c-Src and Abl was investigated, and the antiproliferative profile against four GBM cell lines was studied. For the most active compounds endowed with antiproliferative efficacy in the low-micromolar range, the effects toward nontumoral, healthy cell lines (fibroblasts FIBRO 2-93 and keratinocytes HaCaT) was investigated. Lastly, the in silico and in vitro ADME properties of all compounds were also assessed. Among the tested compounds, the promising inhibitory activity against c-Src and Abl (K_i 3.14 µM and 0.44 µM, respectively), the irreversible, apoptotic-mediated death toward U-87, LN18, LN229, and DBTRG GBM cell lines (IC₅₀ 6.8 µM, 10.8 µM, 6.9 µM, and 8.5 µM, respectively), the significant reduction in GBM cell migration, the safe profile toward FIBRO 2-93 and HaCaT healthy cell lines (CC₅₀ 91.7 µM and 126.5 µM, respectively), the high metabolic stability, and the excellent passive permeability across gastrointestinal and blood-brain barriers led us to select compound 5 for further in vivo assays.

Ion Channels in Gliomas-From Molecular Basis to Treatment

Ion channels provide the basis for the nervous system's intrinsic electrical activity. Neuronal excitability is a characteristic property of neurons and is critical for all functions of the nervous system. Glia cells fulfill essential supportive roles, but unlike neurons, they also retain the ability to divide. This can lead to uncontrolled growth and the formation of gliomas. Ion channels are involved in the unique biology of gliomas pertaining to peritumoral pathology and seizures, diffuse invasion, and treatment resistance. The emerging picture shows ion channels in the brain at the crossroads of neurophysiology and fundamental pathophysiological processes of specific cancer behaviors as reflected by uncontrolled proliferation, infiltration, resistance to apoptosis, metabolism, and angiogenesis. Ion channels are highly druggable, making them an enticing therapeutic target. Targeting ion channels in difficult-to-treat brain tumors such as gliomas requires an understanding of their extremely heterogenous tumor microenvironment and highly diverse molecular profiles, both representing major causes of recurrence and treatment resistance. In this review, we survey the current knowledge on ion channels with oncogenic behavior within the heterogeneous group of gliomas, review ion channel gene expression as genomic biomarkers for glioma prognosis and provide an update on therapeutic perspectives for repurposed and novel ion channel inhibitors and electrotherapy.

Anti-Vimentin Nanobody Decreases Glioblastoma Cell Invasion In Vitro and In Vivo

PURPOSE

Glioblastoma (GBM) is the most common primary brain tumour and one of the deadliest cancers. In addition to late diagnosis and inadequate treatment, the extremely low survival rate is also due to the lack of appropriate therapeutic biomarkers and corresponding therapeutic agents. One of the potential therapeutic biomarkers is the intermediate filament vimentin, which is associated with epithelial-mesenchymal transition (EMT). The purpose of this study was to analyse the effect of the anti-vimentin nanobody Nb79 on cell invasion in vitro and in vivo. To further our understanding of the mechanism of action, we investigated the association between Nb79 and EMT in GBM and GBM stem cells by analysing the expression levels of key EMT-related proteins.

METHODS

The expression of vimentin in glioma tissues and cells was determined by RT-qPCR. An invasion assay was performed on differentiated glioblastoma cell line U-87 MG and stem cell line NCH421k in vitro as well as in vivo in zebrafish embryos. The effect of Nb79 on expression of EMT biomarkers beta-catenin, vimentin, ZEB-1 and ZO1 was determined by Western blot and immunocytochemistry.

RESULTS

Our study shows that vimentin is upregulated in glioblastoma tissue compared to lower grade glioma and non-tumour brain tissue. We demonstrated that treatment with Nb79 reduced glioblastoma cell invasion by up to 64% in vitro and up to 21% in vivo. In addition, we found that the tight junction protein ZO-1 had higher expression on the cell membrane, when treated with inhibitory anti-vimentin Nb79 compared to control.

CONCLUSION

In conclusion, our results suggest that anti-vimentin nanobody Nb79 is a promising tool to target glioblastoma cell invasion.

Glioblastoma multiforme: Diagnosis, treatment, and invasion

Glioblastoma multiforme (GBM) is an essentially incurable brain tumor, which has been explored for approximately a century. Nowadays, surgical resection, chemotherapy, and radiation therapy are still the standardized therapeutic options. However, due to the intrinsic invasion and metastasis features and the resistance to chemotherapy, the survival rate of glioblastoma patients remains unsatisfactory. To improve the current situation, much more research is needed to provide comprehensive knowledge of GBM. In this review, we summarize the latest updates on GBM treatment and invasion. Firstly, we review the traditional and emerging therapies that have been used for GBM treatment. Given the limited efficiency of these therapies, we further discuss the role of invasion in GBM recurrence and progression, and present current research progress on the mode and mechanisms of GBM invasion.

Dynamically Crosslinked Poly(ethylene-glycol) Hydrogels Reveal a Critical Role of Viscoelasticity in Modulating Glioblastoma Fates and Drug Responses in 3D

Glioblastoma multiforme (GBM) is the most prevalent and aggressive brain tumor in adults. Hydrogels have been employed as 3D in vitro culture models to elucidate how matrix cues such as stiffness and degradation drive GBM progression and drug responses. Recently, viscoelasticity has been identified as an important niche cue in regulating stem cell differentiation and morphogenesis in 3D. Brain is a viscoelastic tissue, yet how viscoelasticity modulates GBM fate and drug response remains largely unknown. Using dynamic hydrazone crosslinking chemistry, a poly(ethylene-glycol)-based hydrogel system with brain-mimicking stiffness and tunable stress relaxation is reported to interrogate the role of viscoelasticity on GBM fates in 3D. The hydrogel design allows tuning stress relaxation without changing stiffness, biochemical ligand density, or diffusion. The results reveal that increasing stress relaxation promotes invasive GBM behavior, such as cell spreading, migration, and GBM stem-like cell marker expression. Furthermore, increasing stress relaxation enhances GBM proliferation and drug sensitivity. Stress-relaxation induced changes on GBM fates and drug response are found to be mediated through the cytoskeleton and transient receptor potential vanilloid-type 4. These results highlight the importance of incorporating viscoelasticity into 3D in vitro GBM models and provide novel insights into how viscoelasticity modulates GBM cell fates.

A novel program of infiltrative control in astrocytomas: ADAM23 depletion promotes cell invasion by activating -secretase complex

Background

Infiltration is a life-threatening growth pattern in malignant astrocytomas and a significant cause of therapy resistance. It results in the tumor cell spreading deeply into the surrounding brain tissue, fostering tumor recurrence and making complete surgical resection impossible. We need to thoroughly understand the mechanisms underlying diffuse infiltration to develop effective therapies.

Methods

We integrated in vitro and in vivo functional assays, RNA sequencing, clinical, and expression information from public data sets to investigate the role of ADAM23 expression coupling astrocytoma's growth and motility.

Results

ADAM23 downregulation resulted in increased infiltration, reduced tumor growth, and improved overall survival in astrocytomas. Additionally, we show that ADAM23 deficiency induces γ-secretase (GS) complex activity, contributing to the production and deposition of the Amyloid-β and release of NICD. Finally, GS ablation in ADAM23-low astrocytomas induced a significant inhibitory effect on the invasive programs.

Conclusions

Our findings reveal a role for ADAM23 in regulating the balance between cell proliferation and invasiveness in astrocytoma cells, proposing GS inhibition as a therapeutic option in ADAM23 low-expressing astrocytomas.

LINC01711 promotes transforming growth factor-beta (TGF-β) induced invasion in glioblastoma multiforme (GBM) by acting as a competing endogenous RNA for miR-34a and promoting ZEB1 expression

GBM is the central nervous system's most aggressive and malignant tumor. TGF-β expression is elevated in GBM, and it promotes invasion and EMT. TGF-β regulates the expression of several lncRNAs, which promote glioma pathogenesis. Here we characterize the role of TGF-β-induced lncRNA- LINC01711 in glioma pathogenesis. We show that LINC01711 expression is significantly upregulated in GBM tissues and is associated with poor overall survival of GBM patients. Loss-of-function studies illustrate that LINC01711 promotes proliferation, migration, and invasion in GBM. In addition, LINC01711 depletion sensitizes glioma cells to Temozolomide (TMZ) induced apoptosis by inhibiting ZEB1 expression. LINC01711 functions as a competing endogenous RNA for miR-34a and promotes ZEB1 expression to regulate invasion. Our findings suggest that LINC01711 is an attractive therapeutic target for GBM.

Jamming Transitions in Astrocytes and Glioblastoma Are Induced by Cell Density and Tension

Collective behavior of cells emerges from coordination of cell-cell-interactions and is important to wound healing, embryonic and tumor development. Depending on cell density and cell-cell interactions, a transition from a migratory, fluid-like unjammed state to a more static and solid-like jammed state or vice versa can occur. Here, we analyze collective migration dynamics of astrocytes and glioblastoma cells using live cell imaging. Furthermore, atomic force microscopy, traction force microscopy and spheroid generation assays were used to study cell adhesion, traction and mechanics. Perturbations of traction and adhesion were induced via ROCK or myosin II inhibition. Whereas astrocytes resided within a non-migratory, jammed state, glioblastoma were migratory and unjammed. Furthermore, we demonstrated that a switch from an unjammed to a jammed state was induced upon alteration of the equilibrium between cell-cell-adhesion and tension from adhesion to tension dominated, via inhibition of ROCK or myosin II. Such behavior has implications for understanding the infiltration of the brain by glioblastoma cells and may help to identify new strategies to develop anti-migratory drugs and strategies for glioblastoma-treatment.

Hsa_circ_0043949 reinforces temozolomide resistance via upregulating oncogene ITGA1 axis in glioblastoma

Temozolomide (TMZ) resistance limits its use in glioblastoma (GBM). Exosomes can carry circular RNAs (circRNAs) to regulate chemoresistance. To date, the role of exosomal hsa_circ_0043949 (circ_0043949) in GBM resistance to TMZ is unclear. Relative expression of circ_0043949 in clinical samples, GBM cell lines, and exosomes was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The half-maximal inhibitory concentration (IC₅₀) of TMZ, cell proliferation, apoptosis, invasion, and migration were analyzed via MTT, EdU, flow cytometry, transwell, and wound-healing assays. Relative protein levels were evaluated by western blotting. Target relationship was predicted by bioinformatics analysis and validated by dual-luciferase reporter and RNA pull-down assays. Exosomes were isolated by ultracentrifugation and verified by transmission electron microscopy, nanoparticle tracking analysis (NTA), and western blotting. The effect of exosomal circ_0043949 on TMZ resistance was validated by xenograft assay. Higher expression of circ_0043949 was gained in TMZ-resistant GBM samples and cells. Inhibition of circ_0043949 reduced TMZ resistance via decreasing IC₅₀ of TMZ, repressing proliferation, invasion, migration, and inducing apoptosis in TMZ-resistant GBM cells. Circ_0043949 mediated integrinalpha1 (ITGA1) expression via function as a miR-876-3p sponge. Circ_0043949 was also upregulated in TMZ-resistant GBM cells-derived exosomes, and exosomal circ_0043949 increased the resistance of TMZ-resistant GBM cells to TMZ in xenograft models. TMZ-resistant GBM cells-derived exosomal circ_0043949 promoted TMZ resistance via upregulating ITGA1 expression via sequestering miR-876-3p, offering a potential target for the treatment of TMZ resistance in GBM.

3D-Engineered Scaffolds to Study Microtubes and Localization of Epidermal Growth Factor Receptor in Patient-Derived Glioma Cells

A major obstacle in glioma research is the lack of in vitro models that can retain cellular features of glioma cells in vivo. To overcome this limitation, a 3D-engineered scaffold, fabricated by two-photon polymerization, is developed as a cell culture model system to study patient-derived glioma cells. Scanning electron microscopy, (live cell) confocal microscopy, and immunohistochemistry are employed to assess the 3D model with respect to scaffold colonization, cellular morphology, and epidermal growth factor receptor localization. Both glioma patient-derived cells and established cell lines successfully colonize the scaffolds. Compared to conventional 2D cell cultures, the 3D-engineered scaffolds more closely resemble in vivo glioma cellular features and allow better monitoring of individual cells, cellular protrusions, and intracellular trafficking. Furthermore, less random cell motility and increased stability of cellular networks is observed for cells cultured on the scaffolds. The 3D-engineered glioma scaffolds therefore represent a promising tool for studying brain cancer mechanobiology as well as for drug screening studies.

Glucose and Inositol Transporters, SLC5A1 and SLC5A3, in Glioblastoma Cell Migration

(1) Background: The recurrence of glioblastoma multiforme (GBM) is mainly due to invasion of the surrounding brain tissue, where organic solutes, including glucose and inositol, are abundant. Invasive cell migration has been linked to the aberrant expression of transmembrane solute-linked carriers (SLC). Here, we explore the role of glucose (SLC5A1) and inositol transporters (SLC5A3) in GBM cell migration. (2) Methods: Using immunofluorescence microscopy, we visualized the subcellular localization of SLC5A1 and SLC5A3 in two highly motile human GBM cell lines. We also employed wound-healing assays to examine the effect of SLC inhibition on GBM cell migration and examined the chemotactic potential of inositol. (3) Results: While GBM cell migration was significantly increased by extracellular inositol and glucose, it was strongly impaired by SLC transporter inhibition. In the GBM cell monolayers, both SLCs were exclusively detected in the migrating cells at the monolayer edge. In single GBM cells, both transporters were primarily localized at the leading edge of the lamellipodium. Interestingly, in GBM cells migrating via blebbing, SLC5A1 and SLC5A3 were predominantly detected in nascent and mature blebs, respectively. (4) Conclusion: We provide several lines of evidence for the involvement of SLC5A1 and SLC5A3 in GBM cell migration, thereby complementing the migration-associated transportome. Our findings suggest that SLC inhibition is a promising approach to GBM treatment.

The Molecular and Cellular Strategies of Glioblastoma and Non-Small-Cell Lung Cancer Cells Conferring Radioresistance

Ionizing radiation (IR) has been shown to play a crucial role in the treatment of glioblastoma (GBM; grade IV) and non-small-cell lung cancer (NSCLC). Nevertheless, recent studies have indicated that radiotherapy can offer only palliation owing to the radioresistance of GBM and NSCLC. Therefore, delineating the major radioresistance mechanisms may provide novel therapeutic approaches to sensitize these diseases to IR and improve patient outcomes. This review provides insights into the molecular and cellular mechanisms underlying GBM and NSCLC radioresistance, where it sheds light on the role played by cancer stem cells (CSCs), as well as discusses comprehensively how the cellular dormancy/non-proliferating state and polyploidy impact on their survival and relapse post-IR exposure.

Glioblastoma cell motility depends on enhanced oxidative stress coupled with mobilization of a sulfurtransferase

Cell motility is critical for tumor malignancy. Metabolism being an obligatory step in shaping cell behavior, we looked for metabolic weaknesses shared by motile cells across the diverse genetic contexts of patients' glioblastoma. Computational analyses of single-cell transcriptomes from thirty patients' tumors isolated cells with high motile potential and highlighted their metabolic specificities. These cells were characterized by enhanced mitochondrial load and oxidative stress coupled with mobilization of the cysteine metabolism enzyme 3-Mercaptopyruvate sulfurtransferase (MPST). Functional assays with patients' tumor-derived cells and -tissue organoids, and genetic and pharmacological manipulations confirmed that the cells depend on enhanced ROS production and MPST activity for their motility. MPST action involved protection of protein cysteine residues from damaging hyperoxidation. Its knockdown translated in reduced tumor burden, and a robust increase in mice survival. Starting from cell-by-cell analyses of the patients' tumors, our work unravels metabolic dependencies of cell malignancy maintained across heterogeneous genomic landscapes.

Glioblastoma cell motility depends on enhanced oxidative stress coupled with mobilization of a sulfurtransferase

Cell motility is critical for tumor malignancy. Metabolism being an obligatory step in shaping cell behavior, we looked for metabolic weaknesses shared by motile cells across the diverse genetic contexts of patients' glioblastoma. Computational analyses of single-cell transcriptomes from thirty patients' tumors isolated cells with high motile potential and highlighted their metabolic specificities. These cells were characterized by enhanced mitochondrial load and oxidative stress coupled with mobilization of the cysteine metabolism enzyme 3-Mercaptopyruvate sulfurtransferase (MPST). Functional assays with patients' tumor-derived cells and -tissue organoids, and genetic and pharmacological manipulations confirmed that the cells depend on enhanced ROS production and MPST activity for their motility. MPST action involved protection of protein cysteine residues from damaging hyperoxidation. Its knockdown translated in reduced tumor burden, and a robust increase in mice survival. Starting from cell-by-cell analyses of the patients' tumors, our work unravels metabolic dependencies of cell malignancy maintained across heterogeneous genomic landscapes.

Lactate dehydrogenases promote glioblastoma growth and invasion via a metabolic symbiosis

Lactate is a central metabolite in brain physiology but also contributes to tumor development. Glioblastoma (GB) is the most common and malignant primary brain tumor in adults, recognized by angiogenic and invasive growth, in addition to its altered metabolism. We show herein that lactate fuels GB anaplerosis by replenishing the tricarboxylic acid (TCA) cycle in absence of glucose. Lactate dehydrogenases (LDHA and LDHB), which we found spatially expressed in GB tissues, catalyze the interconversion of pyruvate and lactate. However, ablation of both LDH isoforms, but not only one, led to a reduction in tumor growth and an increase in mouse survival. Comparative transcriptomics and metabolomics revealed metabolic rewiring involving high oxidative phosphorylation (OXPHOS) in the LDHA/B KO group which sensitized tumors to cranial irradiation, thus improving mouse survival. When mice were treated with the antiepileptic drug stiripentol, which targets LDH activity, tumor growth decreased. Our findings unveil the complex metabolic network in which both LDHA and LDHB are integrated and show that the combined inhibition of LDHA and LDHB strongly sensitizes GB to therapy.

Secreted phosphoprotein 1 promotes angiogenesis of glioblastoma through upregulating PSMA expression via transcription factor HIF-1α

Glioblastoma multiforme (GBM) is a highly vascularized malignant brain tumor. Our previous study showed that prostate-specific membrane antigen (PSMA) promotes angiogenesis of GBM. However, the specific mechanism underlying GBM-induced PSMA upregulation remains unclear. In this study, we demonstrate that the GBM-secreted cytokine phosphoprotein 1 (SPP1) can regulate the expression of PSMA in human umbilical vein endothelial cells (HUVECs). Our mechanistic study further reveals that SPP1 regulates the expression of PSMA through the transcription factor HIF1α. Moreover, SPP1 promotes HUVEC migration and tube formation. In addition, HIF1α knockdown reduces the expression of PSMA in HUVECs and blocks the ability of SPP1 to promote HUVEC migration and tube formation. We further confirm that SPP1 is abundantly expressed in GBM, is associated with poor prognosis, and has high clinical diagnostic value with considerable sensitivity and specificity. Collectively, our findings identify that the GBM-secreted cytokine SPP1 upregulates PSMA expression in endothelial cells via the transcription factor HIF1α, providing insight into the angiogenic process and promising candidates for targeted GBM therapy.

BTB domain and CNC homolog 1 promotes glioma invasion mainly through regulating extracellular matrix and increases ferroptosis sensitivity

BTB Domain and CNC Homolog 1 (Bach1) has been implicated in cancer progression, particularly in invasion, but little is unknown about its effect on glioma. Here, we confirmed that highly expressed Bach1 prominently promoted glioma invasion. Similar to the reported mechanisms in other tumors, Bach1 upregulation was also correlated with epithelial mesenchymal transition (EMT) in glioma cells. More importantly, proteomic analysis indicated that the main mechanism of Bach1 promoting invasion in glioma involved extracellular matrix (ECM). We further found thatBach1 upregulation was associated with the multiple mechanisms of ECM remodeling in glioma, including increasing the expression and deposition of ECM components, activating TGFBR2-smad2/3 signaling, promoting invadopodia formation and inducing the expression and secretion of MMP2. Meanwhile, Bach1 overexpression increased ferroptosis sensitivity in glioma cells. The ferroptosis inducer (sulfasalazine) obviously suppressed the gliomas with Bach1 upregulation in vitro and in vivo. Overall, Bach1 has a two-faced role in glioma. Highly expressed Bach1 promotes glioma invasion. Conversely, Bach1 upregulation is also a potential indicator of the sensitivity of ferroptosis inducers.

An update on the molecular biology of glioblastoma, with clinical implications and progress in its treatment

Glioblastoma multiforme (GBM) is the most aggressive and common malignant primary brain tumor. Patients with GBM often have poor prognoses, with a median survival of ∼15 months. Enhanced understanding of the molecular biology of central nervous system tumors has led to modifications in their classifications, the most recent of which classified these tumors into new categories and made some changes in their nomenclature and grading system. This review aims to give a panoramic view of the last 3 years' findings in glioblastoma characterization, its heterogeneity, and current advances in its treatment. Several molecular parameters have been used to achieve an accurate and personalized characterization of glioblastoma in patients, including epigenetic, genetic, transcriptomic and metabolic features, as well as age- and sex-related patterns and the involvement of several noncoding RNAs in glioblastoma progression. Astrocyte-like neural stem cells and outer radial glial-like cells from the subventricular zone have been proposed as agents involved in GBM of IDH-wildtype origin, but this remains controversial. Glioblastoma metabolism is characterized by upregulation of the PI3K/Akt/mTOR signaling pathway, promotion of the glycolytic flux, maintenance of lipid storage, and other features. This metabolism also contributes to glioblastoma's resistance to conventional therapies. Tumor heterogeneity, a hallmark of GBM, has been shown to affect the genetic expression, modulation of metabolic pathways, and immune system evasion. GBM's aggressive invasion potential is modulated by cell-to-cell crosstalk within the tumor microenvironment and altered expressions of specific genes, such as ANXA2, GBP2, FN1, PHIP, and GLUT3. Nevertheless, the rising number of active clinical trials illustrates the efforts to identify new targets and drugs to treat this malignancy. Immunotherapy is still relevant for research purposes, given the amount of ongoing clinical trials based on this strategy to treat GBM, and neoantigen and nucleic acid-based vaccines are gaining importance due to their antitumoral activity by inducing the immune response. Furthermore, there are clinical trials focused on the PI3K/Akt/mTOR axis, angiogenesis, and tumor heterogeneity for developing molecular-targeted therapies against GBM. Other strategies, such as nanodelivery and computational models, may improve the drug pharmacokinetics and the prognosis of patients with GBM.

Spatiotemporal analysis of induced neural stem cell therapy to overcome advanced glioblastoma recurrence

Genetically engineered neural stem cells (NSCs) are a promising therapy for the highly aggressive brain cancer glioblastoma (GBM); however, treatment durability remains a major challenge. We sought to define the events that contribute to dynamic adaptation of GBM during treatment with human skin-derived induced NSCs releasing the pro-apoptotic agent TRAIL (iNSC-TRAIL) and develop strategies that convert initial tumor kill into sustained GBM suppression. In vivo and ex vivo analysis before, during, and after treatment revealed significant shifts in tumor transcriptome and spatial distribution as the tumors adapted to treatment. To address this, we designed iNSC delivery strategies that increased spatiotemporal TRAIL coverage and significantly decreased GBM volume throughout the brain, reducing tumor burden 100-fold as quantified in live ex vivo brain slices. The varying impact of different strategies on treatment durability and median survival of both solid and invasive tumors provides important guidance for optimizing iNSC therapy.

Glioblastoma Invasiveness and Collagen Secretion Are Enhanced by Vitamin C

Aims: Glioblastoma (GB) is one of the most aggressive brain tumors. These tumors modify their metabolism, increasing the expression of glucose transporters, GLUTs, which incorporate glucose and the oxidized form of vitamin C, dehydroascorbic acid (DHA). We hypothesized that GB cells preferentially take up DHA, which is intracellularly reduced and compartmentalized into the endoplasmic reticulum (ER), promoting collagen biosynthesis and an aggressive phenotype. Results: Our results showed that GB cells take up DHA using GLUT1, while GLUT3 and sodium-dependent vitamin C transporter 2 (SVCT2) are preferably intracellular. Using a baculoviral system and reticulum-enriched extracts, we determined that SVCT2 is mainly located in the ER and corresponds to a short isoform. Ascorbic acid (AA) was compartmentalized, stimulating collagen IV secretion and increasing in vitro and in situ cell migration. Finally, orthotopic xenografts induced in immunocompetent guinea pigs showed that vitamin C deficiency retained collagen, reduced blood vessel invasion, and affected glomeruloid vasculature formation, all pathological conditions associated with malignancy. Innovation and Conclusion: We propose a functional role for vitamin C in GB development and progression. Vitamin C is incorporated into the ER of GB cells, where it favors the synthesis of collagen, thus impacting tumor development. Collagen secreted by tumor cells favors the formation of the glomeruloid vasculature and enhances perivascular invasion. Antioxid. Redox Signal. 37, 538-559.

β2-Adrenergic receptor agonist enhances the bystander effect of HSV-TK/GCV gene therapy in glioblastoma multiforme via upregulation of connexin 43 expression

Glioblastoma multiforme (GBM) is the most invasive form of primary brain astrocytoma. Gene therapy using the herpes simplex virus thymidine kinase/ganciclovir (HSV-TK/GCV) is a new strategy for GBM treatment. As the connexin 43 (Cx43) levels are downregulated in GBM cells, it seems that the upregulation of Cx43 could improve the efficacy of the gene therapy. This study aims to evaluate the effect of clenbuterol hydrochloride (Cln) as a β2-adrenergic receptor agonist on HSV-TK/GCV gene therapy efficacy in human GBM cells using olfactory ensheathing cells (OECs) as vectors. The lentivirus containing the thymidine kinase gene was transduced to OECs and the effective dose of GCV on cells was measured by MTT assay. We found that Cln upregulated Cx43 expression in human GBM cells and OECs and promoted the cytotoxic effect of GCV on the co-culture cells. Western blot results showed that Cln increased the cleaved caspase-3 expression and the Bax/Bcl2 ratio in the co-culture of GBM cells and OEC-TK. Also, the flow cytometry results revealed that Cln increased apoptosis in the co-culture of GBM cells and OEC-TK cells. This study showed that Cln via upregulation of Cx43 expression could enhance the bystander effect of HSVTK-GCV gene therapy in human GBM cells.

Lactate metabolism in human health and disease

The current understanding of lactate extends from its origins as a byproduct of glycolysis to its role in tumor metabolism, as identified by studies on the Warburg effect. The lactate shuttle hypothesis suggests that lactate plays an important role as a bridging signaling molecule that coordinates signaling among different cells, organs and tissues. Lactylation is a posttranslational modification initially reported by Professor Yingming Zhao’s research group in 2019. Subsequent studies confirmed that lactylation is a vital component of lactate function and is involved in tumor proliferation, neural excitation, inflammation and other biological processes. An indispensable substance for various physiological cellular functions, lactate plays a regulatory role in different aspects of energy metabolism and signal transduction. Therefore, a comprehensive review and summary of lactate is presented to clarify the role of lactate in disease and to provide a reference and direction for future research. This review offers a systematic overview of lactate homeostasis and its roles in physiological and pathological processes, as well as a comprehensive overview of the effects of lactylation in various diseases, particularly inflammation and cancer.

Role of Transmembrane Water Exchange in Glioma Invasion/Migration: In Vivo Preclinical Study by Relaxometry at Very Low Magnetic Field

This work shows that the longitudinal relaxation differences observed at very low magnetic fields between invasion/migration and proliferation processes on glioma mouse models in vivo are related to differences in the transmembrane water exchange basically linked to the aquaporin expression changes. Three glioma mouse models were used: Glio6 and Glio96 as invasion/migration models and U87 as cell proliferation model. In vivo proton longitudinal relaxation-rate constants (R1) at very low fields were measured by fast field cycling NMR (FFC-NMR). The tumor contribution to the observed proton relaxation rate, R1tum (U87: 12.26 ± 0.64 s−1; Glio6: 3.76 ± 0.88 s−1; Glio96: 6.90 ± 0.64 s−1 at 0.01 MHz), and the intracellular water lifetime, τin (U87: 826 ± 19 ms; Glio6: 516 ± 8 ms; Glio96: 596 ± 15 ms), were found to be good diagnostic hallmarks to distinguish invasion/migration from proliferation (p < 0.01 and 0.001). Overexpression of AQP4 and AQP1 were assessed in invasion/migration models, highlighting the pathophysiological role of these two aquaporins in water exchange that, in turn, determine the lower values in the observed R1 relaxation rate constant in glioma invasion/migration. Overall, our findings demonstrate that τin and R1 (measured at very low fields) are relevant biomarkers, discriminating invasion/migration from proliferation in vivo. These results highlight the use of FFC-NMR and FFC-imaging to assess the efficiency of drugs that could modulate aquaporin functions.

Brain Functional Connectivity in Low- and High-Grade Gliomas: Differences in Network Dynamics Associated with Tumor Grade and Location

Brain tumors lead to modifications of brain networks. Graph theory plays an important role in clarifying the principles of brain connectivity. Our objective was to investigate network modifications related to tumor grade and location using resting-state functional magnetic resonance imaging (fMRI) and graph theory. We retrospectively studied 30 low-grade (LGG), 30 high-grade (HGG) left-hemispheric glioma patients and 20 healthy controls (HC) with rs-fMRI. Tumor location was labeled as: frontal, temporal, parietal, insular or occipital. We collected patients’ clinical data from records. We analyzed whole-brain and hemispheric networks in all patients and HC. Subsequently, we studied lobar networks in subgroups of patients divided by tumor location. Seven graph-theoretical metrics were calculated (FDR p < 0.05). Connectograms were computed for significant nodes. The two-tailed Student t-test or Mann−Whitney U-test (p < 0.05) were used to compare graph metrics and clinical data. The hemispheric network analysis showed increased ipsilateral connectivity for LGG (global efficiency p = 0.03) and decreased contralateral connectivity for HGG (degree/cost p = 0.028). Frontal and temporal tumors showed bilateral modifications; parietal and insular tumors showed only local effects. Temporal tumors led to a bilateral decrease in all graph metrics. Tumor grade and location influence the pattern of network reorganization. LGG may show more favorable network changes than HGG, reflecting fewer clinical deficits.

Identification of growth hormone receptor as a relevant target for precision medicine in low-EGFR expressing glioblastoma

Objective

New therapeutic approaches are needed to improve the prognosis of glioblastoma (GBM) patients.

Methods

With the objective of identifying alternative oncogenic mechanisms to abnormally activated epidermal growth factor receptor (EGFR) signalling, one of the most common oncogenic mechanisms in GBM, we performed a comparative analysis of gene expression profiles in a series of 54 human GBM samples. We then conducted gain of function as well as genetic and pharmocological inhibition assays in GBM patient‐derived cell lines to functionnally validate our finding.

Results

We identified that growth hormone receptor (GHR) signalling defines a distinct molecular subset of GBMs devoid of EGFR overexpression. GHR overexpression was detected in one third of patients and was associated with low levels of suppressor of cytokine signalling 2 (SOCS2) expression due to SOCS2 promoter hypermethylation. In GBM patient‐derived cell lines, GHR signalling modulates the expression of proteins involved in cellular movement, promotes cell migration, invasion and proliferation in vitro and promotes tumourigenesis, tumour growth, and tumour invasion in vivo. GHR genetic and pharmacological inhibition reduced cell proliferation and migration in vitro.

Conclusion

This study pioneers a new field of investigation to improve the prognosis of GBM patients.

IFN-γ induces PD-L1 through p38/JNK/ERK signaling pathways and counteracts the tumor promoting effect mediated by PD-L1 in Glioblastoma

Glioblastoma is the most malignant primary glioma. Conventional treatment methods that include surgery, radiotherapy, and chemotherapy have a limited curative effect on the tumor. With the deepening of molecular biology research, molecular targeted therapy has opened a new era of tumor therapy. Programmed death ligand 1 (PD-L1) has been proved to play a pivotal role in the tumor immune evasion process. Previous studies have confirmed the specific expression of PD-L1 in glioblastoma tissues and cells, but there are few studies on inflammation regulating PD-L1 in glioblastoma. In this study, real-time PCR, flow cytometry, and western blot were applied to detect PD-L1 in glioblastoma cells. Short hairpin RNA was used to knock down PD-L1 in glioblastoma cells. Cell counting kit-8 experiment and wound-healing assay were used to detect the proliferation and migration of glioblastoma cells. Here we demonstrated that PD-L1 was overexpressed in glioblastoma cells, and interferon-gamma (IFN-γ) induces PD-L1 in glioblastoma cells via activating p38/JNK/ERK signaling pathways. To summarize, PD-L1 promotes the occurrence and development of glioblastoma. IFN-γ counteracts the tumor-promoting effects mediated by PD-L1 in glioblastoma. IFN-γ regulates PD-L1 through multiple signaling pathways, but the total effect of IFN-γ-mediated inflammatory signals still need to be further explored in glioblastoma. PD-L1 enhances the proliferation and migration of glioblastoma cells by regulating CDK4, CDK6, MMP-2, and vimentin molecules. Most importantly, targeting PD-L1 can be applied in the treatment of glioblastoma. We speculate that IFN-γ may affect glioblastoma through other pathways, and we will continue to further explore the mechanisms in the future.

Peptide-based targeted cancer therapeutics: design, synthesis and biological evaluation

Cancer is the leading cause for human mortality together with cardiovascular diseases. Abl (Abelson) tyrosine kinases play a fundamental role in transducing various signals that control proliferation, survival, migration and invasion in several cancers such as Chronic Myeloid Leukemia (CML), breast cancer and brain cancer. For these reasons Abl tyrosine kinases are considered important biological targets in drug discovery. In this study a series of lysine-based oligopeptides with expected Abl inhibitory activity were designed resembling the binding of FDA-approved drugs (i.e. of Imatinib and Nilotinib), synthesized, purified by High Performance Liquid Chromatography (HPLC), analyzed by mass spectrometry (MS) and biologically tested in vitro in CML (AR-230 and K-562), breast cancers (MDA-MB 231 and MDA-MB 468) and glioblastoma cell lines (U87 and U118). The solid-phase peptide synthesis (SPPS) by Fmoc (9-fluorenylmethoxycarbonyl) chemistry was used to synthesize target compounds. AutoDock Vina was applied for simulation binding to Abl. The biological activities were measured evaluating cytotoxic effect, induction of apoptosis and inhibition of cancer cells migration. The new peptides exhibited different concentration-dependent antiproliferative effect against the tumor cell lines after 72 h treatment. The most promising results were obtained with the U87 glioblastoma cell line where a significant reduction of the migration ability was detected with one compound (H-Lys¹-Lys²-Lys³-NH₂).

Drug Delivery Systems in the Development of Novel Strategies for Glioblastoma Treatment

Glioblastoma multiforme (GBM) is a grade IV glioma considered the most fatal cancer of the central nervous system (CNS), with less than a 5% survival rate after five years. The tumor heterogeneity, the high infiltrative behavior of its cells, and the blood-brain barrier (BBB) that limits the access of therapeutic drugs to the brain are the main reasons hampering the current standard treatment efficiency. Following the tumor resection, the infiltrative remaining GBM cells, which are resistant to chemotherapy and radiotherapy, can further invade the surrounding brain parenchyma. Consequently, the development of new strategies to treat parenchyma-infiltrating GBM cells, such as vaccines, nanotherapies, and tumor cells traps including drug delivery systems, is required. For example, the chemoattractant CXCL12, by binding to its CXCR4 receptor, activates signaling pathways that play a critical role in tumor progression and invasion, making it an interesting therapeutic target to properly control the direction of GBM cell migration for treatment proposes. Moreover, the interstitial fluid flow (IFF) is also implicated in increasing the GBM cell migration through the activation of the CXCL12-CXCR4 signaling pathway. However, due to its complex and variable nature, the influence of the IFF on the efficiency of drug delivery systems is not well understood yet. Therefore, this review discusses novel drug delivery strategies to overcome the GBM treatment limitations, focusing on chemokines such as CXCL12 as an innovative approach to reverse the migration of infiltrated GBM. Furthermore, recent developments regarding in vitro 3D culture systems aiming to mimic the dynamic peritumoral environment for the optimization of new drug delivery technologies are highlighted.

Aberrant expression of microRNA-4443 (miR-4443) in human diseases

miRNA is a small endogenous RNA and an important regulator of gene expression. miR-4443 is abnormally expressed in 12 diseases including cancer. The expression of miR-4443 is regulated by 3 upstream factors. miR-4443 has 12 downstream target genes. miR-4443 inhibits the expression of its target genes, thereby affecting the migration, proliferation, and invasion of pathological cells. miR-4443 participates in 4 signaling pathways and plays a role in the occurrence and development of several diseases. In addition, miR-4443 can also promote resistance to multiple drugs. Here, this article summarizes the aberrant expression of miR-4443 and its pathogenic molecular mechanisms in human diseases, which provides clues and directions for the follow-up research of miR-4443.

Fast-field-cycling NMR at very low magnetic fields: water molecular dynamic biomarkers of glioma cell invasion and migration

Our objective was to study NMR relaxometry of glioma invasion/migration at very low field (<2 mT) by fast-field-cycling NMR (FFC-NMR) and to decipher the pathophysiological processes of glioma that are responsible for relaxation changes in order to open a new diagnostic method that can be extended to imaging. The phenotypes of two new glioma mouse models, Glio6 and Glio96, were characterized by T_2w -MRI, HE histology, Ki-67 immunohistochemistry (IHC) and CXCR4 RT-qPCR, and were compared with the U87 model. R₁ dispersions of glioma tissues were acquired at low field (0.1 mT-0.8 T) ex vivo and were fitted with Lorentzian and power-law models to extract FFC biomarkers related to the molecular dynamics of water. In order to decipher relaxation changes, three main invasion/migration pathophysiological processes were studied: hypoxia, H₂ O₂ function and the water-channel aquaporin-4 (AQP4). Glio6 and Glio96 were characterized with invasion/migration phenotype and U87 with high cell proliferation as a solid glioma. At very low field, invasion/migration versus proliferation was characterized by a decrease in the relaxation-rate constant (ΔR₁  ≈ -32% at 0.1 mT) and correlation time (≈-40%). These decreases corroborated the AQP4-IHC overexpression (Glio6/Glio96: +92%/+46%), suggesting rapid transcytolemmal water exchange, which was confirmed by the intracellular water-lifetime τ_IN decrease (Δτ_IN  ≈ -30%). In functional experiments, AQP4 expression, τ_IN and the relaxation-rate constant at very low field were all found to be sensitive to hypoxia and to H₂ O₂ stimuli. At very low field the role of water exchanges in relaxation modulation was confirmed, and for the first time it was linked to the glioma invasion/migration and to its main pathophysiological processes: hypoxia, H₂ O₂ redox signaling and AQP4 expression. The method appears appropriate to evaluate the effect of drugs that can target these pathophysiological mechanisms. Finally, FFC-NMR operating at low field is demonstrated to be sensitive to invasion glioma phenotype and can be straightforwardly extended to FFC-MRI as a new cancer invasion imaging method in the clinic.

Dialogue among Lymphocytes and Microglia in Glioblastoma Microenvironment

Simple Summary

In this review, we summarize in vitro and in vivo studies related to glioblastoma models and human patients to outline the symbiotic bidirectional interaction between microglia, lymphocytes, and tumor cells that develops during tumor progression. Particularly, we highlight the current experimental therapeutic approaches that aim to shape these interplays, such as adeno-associated virus (AAV) delivery and CAR-T and -NK cell infusion, and to modulate the tumor microenvironment in an anti-tumoral way, thus counteracting glioblastoma growth.

Abstract

Microglia and lymphocytes are fundamental constituents of the glioblastoma microenvironment. In this review, we summarize the current state-of-the-art knowledge of the microglial role played in promoting the development and aggressive hallmarks of this deadly brain tumor. Particularly, we report in vitro and in vivo studies related to glioblastoma models and human patients to outline the symbiotic bidirectional interaction between microglia, lymphocytes, and tumor cells that develops during tumor progression. Furthermore, we highlight the current experimental therapeutic approaches that aim to shape these interplays, such as adeno-associated virus (AAV) delivery and CAR-T and -NK cell infusion, and to modulate the tumor microenvironment in an anti-tumoral way, thus counteracting glioblastoma growth.

TGIF1 overexpression promotes glioma progression and worsens patient prognosis

Transforming growth factor β-induced factor homeobox 1 (TGIF1) reportedly promotes the pathological processes of various malignant tumors. However, few studies have investigated the role of TGIF1 in gliomas. We aimed to explore the relationship between TGIF1 expression and the clinical characteristics of patients with glioma, including their overall survival. A total of thousands transcriptome datapoints were downloaded from public databases to determine the correlations between TGIF1 and various clinicopathological features using the Wilcoxon or Kruskal-Wallis tests. The Kaplan-Meier and Cox statistical methods were used to explore the prognostic significance of TGIF1. Gene set enrichment analysis (GSEA) was used to indirectly identify the pathological mechanisms modulated by TGIF1, and compounds that inhibit its expression were determined using a connectivity map (CMap). TGIF1 was significantly overexpressed in gliomas and was correlated with unfavorable prognostic factors and shorter overall survival. Cox analysis confirmed that TGIF1 expression was a significant predictor of poor prognosis in patients with glioma. GSEA revealed that the signaling pathways associated with TGIF1 expression in glioma included extracellular matrix receptor- and cell cycle-modulating proteins. CMap analysis showed that the small molecules scriptaid, torasemide, dexpropranolol, ipratropium bromide, and harmine were potential negative regulators of TGIF1. Finally, in vitro experiments demonstrated that knockdown of TGIF1 significantly inhibited the proliferation and invasion of glioma cell. Taken together, our study, which is the first to comprehensively analyze TGIF1 in gliomas, revealed it to be a novel oncogene in terms of its association with this disease. As such, TGIF1 may be a potential therapeutic target for individualized treatment of patients with glioma.