Targeting cellular pathways in glioblastoma multiforme

The impact of autophagy during the development and survival of glioblastoma

Glioblastoma is the most common and aggressive adult brain tumour, with poor median survival and limited treatment options. Following surgical resection and chemotherapy, recurrence of the disease is inevitable. Genomic studies have identified key drivers of glioblastoma development, including amplifications of receptor tyrosine kinases, which drive tumour growth. To improve treatment, it is crucial to understand survival response processes in glioblastoma that fuel cell proliferation and promote resistance to treatment. One such process is autophagy, a catabolic pathway that delivers cellular components sequestered into vesicles for lysosomal degradation. Autophagy plays an important role in maintaining cellular homeostasis and is upregulated during stress conditions, such as limited nutrient and oxygen availability, and in response to anti-cancer therapy. Autophagy can also regulate pro-growth signalling and metabolic rewiring of cancer cells in order to support tumour growth. In this review, we will discuss our current understanding of how autophagy is implicated in glioblastoma development and survival. When appropriate, we will refer to findings derived from the role of autophagy in other cancer models and predict the outcome of manipulating autophagy during glioblastoma treatment.

The uses of resveratrol for neurological diseases treatment and insights for nanotechnology based-drug delivery systems

Neurological disorders have been growing in recent years and are highly prevalent globally. Resveratrol (RES) is a natural product from plant sources such as grape skins. This compound has shown biological activity in many diseases, in particular, those that act on the central nervous system. The mechanism of action and the key points in neurological disorders were described and show the targeted mechanism of action. Due to the insolubility of this compound; the use of nanotechnology-based systems has been proposed for the incorporation of RES and RES-loaded nanocarriers have been designed for intranasal administration, oral or parenteral routes to deliver it to the brain. In general, these nanosystems have shown to be effective in many studies, pharmacological and pharmacokinetic assays, as well as some cell studies. The outcomes show that RES has been reported in human clinical trials for some neurological diseases, although no studies were performed in humans using nanocarriers, animal and/or cellular models have been reported to show good results regarding therapeutics on neurological diseases. Thus, the use of this nutraceutical has shown true for neurological diseases and its loading into nanocarriers displaying good results on the stability, delivery and targeting to the brain.

Flavagline synthetic derivative induces senescence in glioblastoma cancer cells without being toxic to healthy astrocytes

Glioblastoma (GBM) is one of the most aggressive types of cancer, which begins within the brain. It is the most invasive type of glioma developed from astrocytes. Until today, Temozolomide (TMZ) is the only standard chemotherapy for patients with GBM. Even though chemotherapy extends the survival of patients, there are many undesirable side effects, and most cases show resistance to TMZ. FL3 is a synthetic flavagline which displays potent anticancer activities, and is known to inhibit cell proliferation, by provoking cell cycle arrest, and leads to apoptosis in a lot of cancer cell lines. However, the effect of FL3 in glioblastoma cancer cells has not yet been examined. Hypoxia is a major problem for patients with GBM, resulting in tumor resistance and aggressiveness. In this study, we explore the effect of FL3 in glioblastoma cells under normoxia and hypoxia conditions. Our results clearly indicate that this synthetic flavagline inhibits cell proliferation and induced senescence in glioblastoma cells cultured under both conditions. In addition, FL3 treatment had no effect on human brain astrocytes. These findings support the notion that the FL3 molecule could be used in combination with other chemotherapeutic agents or other therapies in glioblastoma treatments.

Omeprazole Inhibits Glioblastoma Cell Invasion and Tumor Growth

Background: The aryl hydrocarbon receptor (AhR) is expressed in gliomas and the highest staining is observed in glioblastomas. A recent study showed that the AhR exhibited tumor suppressor-like activity in established and patient-derived glioblastoma cells and genomic analysis showed that this was due, in part, to suppression of CXCL12, CXCR4 and MMP9. Methods: Selective AhR modulators (SAhRMs) including AhR-active pharmaceuticals were screened for their inhibition of invasion using a spheroid invasion assay in patient-derived AhR-expressing 15-037 glioblastoma cells and in AhR-silenced 15-037 cells. Invasion, migration and cell proliferation were determined using spheroid invasion, Boyden chambers and scratch assay, and XTT metabolic assays for cell growth. Changes in gene and gene product expression were determined by real-time PCR and Western blot assays, respectively. In vivo antitumorigenic activity of omeprazole was determined in SCID mice bearing subcutaneous patient-derived 15-037 cells. Results: Results of a screening assay using patient-derived 15-037 cells (wild-type and AhR knockout) identified the AhR-active proton pump inhibitor omeprazole as an inhibitor of glioblastoma cell invasion and migration only AhR-expressing cells but not in cells where the AhR was downregulated. Omeprazole also enhanced AhR-dependent repression of the pro-invasion CXCL12, CXCR4 and MMP9 genes, and interactions and effectiveness of omeprazole plus temozolomide were response-dependent. Omeprazole (100 mg/kg/injection) inhibited and delayed tumors in SCID mice bearing patient-derived 15-037 cells injected subcutaneously. Conclusion: Our results demonstrate that omeprazole enhances AhR-dependent inhibition of glioblastoma invasion and highlights a potential new avenue for development of a novel therapeutic mechanism-based approach for treating glioblastoma.

Hybrid Magnetic Nanovectors Promote Selective Glioblastoma Cell Death through a Combined Effect of Lysosomal Membrane Permeabilization and Chemotherapy

Glioblastoma multiforme is the most aggressive brain tumor, due to its high invasiveness and genetic heterogeneity. Moreover, the blood-brain barrier prevents many drugs from reaching a therapeutic concentration at the tumor site, and most of the chemotherapeutics lack in specificity toward cancer cells, accumulating in both healthy and diseased tissues, with severe side effects. Here, we present in vitro investigations on lipid-based nanovectors encapsulating a drug, nutlin-3a, and superparamagnetic iron oxide nanoparticles, to combine the proapoptotic action of the drug and the hyperthermia mediated by superparamagnetic iron oxide nanoparticles stimulated with an alternating magnetic field. The nanovectors are functionalized with the peptide angiopep-2 to induce receptor-mediated transcytosis through the blood-brain barrier and to target a receptor overexpressed by glioma cells. The glioblastoma multiforme targeting efficiency and the blood-brain barrier crossing abilities were tested through in vitro fluidic models, where different human cell lines were placed to mimic the tumor microenvironment. These nanovectors successfully cross the blood-brain barrier model, maintaining their targeting abilities for glioblastoma multiforme with minimal interaction with healthy cells. Moreover, we showed that nanovector-assisted hyperthermia induces a lysosomal membrane permeabilization that not only initiates a caspase-dependent apoptotic pathway, but also enhances the anticancer efficacy of the drug.

Potential roads for reaching the summit: an overview on target therapies for high-grade gliomas

Background:

The tailored targeting of specific oncogenes represents a new frontier in the treatment of high-grade glioma in the pursuit of innovative and personalized approaches. The present study consists in a wide-ranging overview of the target therapies and related translational challenges in neuro-oncology.

Methods:

A review of the literature on PubMed/MEDLINE on recent advances concerning the target therapies for treatment of central nervous system malignancies was carried out. In the Medical Subject Headings, the terms “Target Therapy”, “Target drug” and “Tailored Therapy” were combined with the terms “High-grade gliomas”, “Malignant brain tumor” and “Glioblastoma”. Articles published in the last five years were further sorted, based on the best match and relevance. The ClinicalTrials.gov website was used as a source of the main trials, where the search terms were “Central Nervous System Tumor”, “Malignant Brain Tumor”, “Brain Cancer”, “Brain Neoplasms” and “High-grade gliomas”.

Results:

A total of 137 relevant articles and 79 trials were selected. Target therapies entailed inhibitors of tyrosine kinases, PI3K/AKT/mTOR pathway, farnesyl transferase enzymes, p53 and pRB proteins, isocitrate dehydrogenases, histone deacetylases, integrins and proteasome complexes. The clinical trials mostly involved combined approaches. They were phase I, II, I/II and III in 33%, 42%, 16%, and 9% of the cases, respectively.

Conclusion:

Tyrosine kinase and angiogenesis inhibitors, in combination with standard of care, have shown most evidence of the effectiveness in glioblastoma. Resistance remains an issue. A deeper understanding of the molecular pathways involved in gliomagenesis is the key aspect on which the translational research is focusing, in order to optimize the target therapies of newly diagnosed and recurrent brain gliomas. (www.actabiomedica.it)

Can COVID-19 induce glioma tumorogenesis through binding cell receptors?

The outbreak of Novel Coronavirus 2019 (COVID-19) represents a global threat to the public healthcare. The viral spike (S) glycoprotein is the key molecule for viral entry through interaction with angiotensin converting enzyme 2 (ACE2) receptor molecules present on the cell membranes. Moreover, it has been established that COVID-19 interacts and infects brain cells in humans via ACE2. Therefore in the light of these known facts we hypothesized that viral S protein molecule may bind to the other overexpressed receptor molecules in glioma cells and may play some role in glioma tumorogenesis. Thus we leverage docking analysis (HEX and Z-DOCK) between viral S protein and epidermal growth factor receptors (EGFR), vascular endothelial growth factor receptors (VEGFR) and hepatocyte growth factor receptors (HGFR/c-MET) to investigate the oncogenic potential of COVID-19. Our findings suggested higher affinity of Viral S protein towards EGFR and VEGFR. Although, the data presented is preliminary and need to be validated further via molecular dynamics studies, however it paves platform to instigate further investigations on this aspect considering the aftermath of COVID-19 pandemic in oncogenic perspective.

Abuhamad A, Syahir A. Understanding Glioblastoma Biomarkers: Knocking a Mountain with a Hammer

Gliomas are the most frequent and deadly form of human primary brain tumors. Among them, the most common and aggressive type is the high-grade glioblastoma multiforme (GBM), which rapidly grows and renders patients a very poor prognosis. Meanwhile, cancer stem cells (CSCs) have been determined in gliomas and play vital roles in driving tumor growth due to their competency in self-renewal and proliferation. Studies of gliomas have recognized CSCs via specific markers. This review comprehensively examines the current knowledge of the most significant CSCs markers in gliomas in general and in glioblastoma in particular and specifically focuses on their outlook and importance in gliomas CSCs research. We suggest that CSCs should be the superior therapeutic approach by directly targeting the markers. In addition, we highlight the association of these markers with each other in relation to their cascading pathways, and interactions with functional miRNAs, providing the role of the networks axes in glioblastoma signaling pathways.

PathME: pathway based multi-modal sparse autoencoders for clustering of patient-level multi-omics data

Background

Recent years have witnessed an increasing interest in multi-omics data, because these data allow for better understanding complex diseases such as cancer on a molecular system level. In addition, multi-omics data increase the chance to robustly identify molecular patient sub-groups and hence open the door towards a better personalized treatment of diseases. Several methods have been proposed for unsupervised clustering of multi-omics data. However, a number of challenges remain, such as the magnitude of features and the large difference in dimensionality across different omics data sources.

Results

We propose a multi-modal sparse denoising autoencoder framework coupled with sparse non-negative matrix factorization to robustly cluster patients based on multi-omics data. The proposed model specifically leverages pathway information to effectively reduce the dimensionality of omics data into a pathway and patient specific score profile. In consequence, our method allows us to understand, which pathway is a feature of which particular patient cluster. Moreover, recently proposed machine learning techniques allow us to disentangle the specific impact of each individual omics feature on a pathway score. We applied our method to cluster patients in several cancer datasets using gene expression, miRNA expression, DNA methylation and CNVs, demonstrating the possibility to obtain biologically plausible disease subtypes characterized by specific molecular features. Comparison against several competing methods showed a competitive clustering performance. In addition, post-hoc analysis of somatic mutations and clinical data provided supporting evidence and interpretation of the identified clusters.

Conclusions

Our suggested multi-modal sparse denoising autoencoder approach allows for an effective and interpretable integration of multi-omics data on pathway level while addressing the high dimensional character of omics data. Patient specific pathway score profiles derived from our model allow for a robust identification of disease subgroups.

Receptor tyrosine kinase targeting in glioblastoma: performance, limitations and future approaches

From all central nervous system tumors, gliomas are the most common. Nowadays, researchers are looking for more efficient treatments for these tumors, as well as ways for early diagnosis. Receptor tyrosine kinases (RTKs) are major targets for oncology and the development of small-molecule RTK inhibitors has been proven successful in cancer treatment. Mutations or aberrant activation of the RTKs and their intracellular signaling pathways are linked to several malignant diseases, including glioblastoma. The progress in the understanding of malignant glioma evolution has led to RTK targeted therapies with high capacity to improve the therapeutic response while reducing toxicity. In this review, we present the most important RTKs (i.e. EGFR, IGFR, PDGFR and VEGFR) currently used for developing cancer therapeutics together with the potential of RTK-related drugs in glioblastoma treatment. Also, we focus on some therapeutic agents that are currently at different stages of research or even in clinical phases and proved to be suitable as re-purposing candidates for glioblastoma treatment.

Melatonin and its anti-glioma functions: a comprehensive review

Melatonin (N-acetyl-5-methoxytryptamine) is a naturally synthesized hormone secreted from the pineal gland in a variety of animals and is primarily involved in the regulation of the circadian rhythm, which is the natural cycle controlling sleep in organisms. Melatonin acts on specific receptors and has an important role in overall energy metabolism. This review encompasses several aspects of melatonin activity, such as synthesis, source, structure, distribution, function, signaling and its role in normal physiology. The review highlights the cellular signaling and messenger systems involved in melatonin's action on the body and their wider implications, the distribution and diverse action of different melatonin receptors in specific areas of the brain, and the pharmacological agonists and antagonists that have specific action on these melatonin receptors. This review also incorporates the antitumor effects of melatonin in considerable detail, emphasizing on melatonin's role as an adjuvant therapeutic agent in glioma treatment. We conclude that the diminishing levels of melatonin have significant debilitating effects on normal physiology and can also be associated with malignant conditions such as glioma. Based on the review of the available evidence, our study provides a broad platform for a better understanding of the specific roles of melatonin and serves as a starting point for further investigation into the therapeutic effect of melatonin in glioma as an adjuvant therapeutic agent.

Tumor Copy Number Deconvolution Integrating Bulk and Single-Cell Sequencing Data

Characterizing intratumor heterogeneity (ITH) is crucial to understanding cancer development, but it is hampered by limits of available data sources. Bulk DNA sequencing is the most common technology to assess ITH, but involves the analysis of a mixture of many genetically distinct cells in each sample, which must then be computationally deconvolved. Single-cell sequencing is a promising alternative, but its limitations-for example, high noise, difficulty scaling to large populations, technical artifacts, and large data sets-have so far made it impractical for studying cohorts of sufficient size to identify statistically robust features of tumor evolution. We have developed strategies for deconvolution and tumor phylogenetics combining limited amounts of bulk and single-cell data to gain some advantages of single-cell resolution with much lower cost, with specific focus on deconvolving genomic copy number data. We developed a mixed membership model for clonal deconvolution via non-negative matrix factorization balancing deconvolution quality with similarity to single-cell samples via an associated efficient coordinate descent algorithm. We then improve on that algorithm by integrating deconvolution with clonal phylogeny inference, using a mixed integer linear programming model to incorporate a minimum evolution phylogenetic tree cost in the problem objective. We demonstrate the effectiveness of these methods on semisimulated data of known ground truth, showing improved deconvolution accuracy relative to bulk data alone.

Inverse screening of Simvastatin kinase targets from glioblastoma druggable kinome

The statin drug Simvastatin is a HMG-CoA reductase inhibitor that has been widely used to lower blood lipid. However, the drug is clinically observed to reposition a significant suppressing potency on glioblastoma (GBM) by unexpectedly targeting diverse kinase pathways involved in GBM tumorigensis. Here, an inverse screening strategy is described to discover potential kinase targets of Simvastatin. Various human protein kinases implicated in GBM are enriched to define a druggable kinome; the binding behavior of Simvastatin to the kinome is profiled systematically via an integrative computational approach, from which most kinases have only low or moderate binding potency to Simvastatin, while only few are identified as promising kinase hits. It is revealed that Simvastatin can potentially interact with certain known targets or key regulators of GBM such as ErbB, c-Src and FGFR signaling pathways, but exhibit low affinity to the well-established GBM target of PI3K/Akt/mTOR pathway. Further assays determine that Simvastatin can inhibit kinase hits EGFR, MET, SRC and HER2 at nanomolar level, which are comparable with those of cognate kinase inhibitors. Structural analyses reveal that the sophisticated T790 M gatekeeper mutation can considerably reduce Simvastatin sensitivity to EGFR by inducing the ligand change between different binding modes.

Lipid Peroxidation Plays an Important Role in Chemotherapeutic Effects of Temozolomide and the Development of Therapy Resistance in Human Glioblastoma

BACKGROUND

Glioblastoma (GBM) is the most malignant primary brain tumor. Relapse occurs regularly, and the clinical behavior seems to be due to a therapy-resistant subpopulation of glioma-initiating cells that belong to the group of cancer stem cells. Aldehyde dehydrogenase (ALDH) has been identified as a marker for this cell population, and we have shown previously that ALDH1A3-positive GBM cells are more resistant against temozolomide (TMZ) treatment. However, it is still unclear how ALDH expression mediates chemoresistance.

MATERIALS AND METHODS

ALDH1A3 expression was analyzed in 112 specimens from primary and secondary surgical resections of 56 patients with GBM (WHO grade IV). All patients received combined adjuvant radiochemotherapy. For experimental analysis, CRISPR-Cas9-induced knockout cells from three established GBM cell lines (LN229, U87MG, T98G) and two glioma stem-like cell lines were investigated after TMZ treatment.

RESULTS

ALDH1A3 knockout cells were more sensitive to TMZ, and oxidative stress seemed to be the molecular process where ALDH1A3 exerts its role in resistance against TMZ. Oxidative stress led to lipid peroxidation, yielding active aldehydes that were detoxified by ALDH enzymatic activity. During the metabolic process, autophagy was induced leading to downregulation of the enzyme, but ALDH1A3 is upregulated to even higher expression levels after finishing the TMZ therapy in vitro. Recurrent GBMs show significantly higher ALDH1A3 expression than the respective samples from the primary tumor, and patients suffering from GBM with high ALDH1A3 expression showed a shorter median survival time (12 months vs 21 months, P < .05).

CONCLUSION

Oxidative stress is an important and clinically relevant component of TMZ-induced therapeutic effects. Cytotoxicity seems to be mediated by aldehydes resulting from lipid peroxidation, and ALDH1A3 is able to reduce the number of toxic aldehydes. Therefore, we present a molecular explanation of the role of ALDH1A3 in therapeutic resistance of human GBM cells.

Glioblastoma multiforme: a glance at advanced therapies based on nanotechnology

Glioblastoma multiforme (GBM, grade IV) is the most common malignant and invasive central nervous system tumor with poor survival outcome. Various pathogenesis signatures such as genetic mutation, hypoxia, necrosis and neo-angiogenesis are involved in GBM. Standard treatment includes surgical resection along with radiation therapy and temozolomide (TMZ) chemotherapy that do not improve the overall survival of patients. In this review, we focused on the diagnosis, risk factors and novel therapies, using advanced therapies such as nanotechnology in drug delivery, gene therapy and hyperthermia that have promising roles in the treatment of aggressive brain tumors.

Open Data for Differential Network Analysis in Glioma

The complexity of cancer diseases demands bioinformatic techniques and translational research based on big data and personalized medicine. Open data enables researchers to accelerate cancer studies, save resources and foster collaboration. Several tools and programming approaches are available for analyzing data, including annotation, clustering, comparison and extrapolation, merging, enrichment, functional association and statistics. We exploit openly available data via cancer gene expression analysis, we apply refinement as well as enrichment analysis via gene ontology and conclude with graph-based visualization of involved protein interaction networks as a basis for signaling. The different databases allowed for the construction of huge networks or specified ones consisting of high-confidence interactions only. Several genes associated to glioma were isolated via a network analysis from top hub nodes as well as from an outlier analysis. The latter approach highlights a mitogen-activated protein kinase next to a member of histondeacetylases and a protein phosphatase as genes uncommonly associated with glioma. Cluster analysis from top hub nodes lists several identified glioma-associated gene products to function within protein complexes, including epidermal growth factors as well as cell cycle proteins or RAS proto-oncogenes. By using selected exemplary tools and open-access resources for cancer research and differential network analysis, we highlight disturbed signaling components in brain cancer subtypes of glioma.

Deep sequencing and automated histochemistry of human tissue slice cultures improve their usability as preclinical model for cancer research

Cancer research requires models closely resembling the tumor in the patient. Human tissue cultures can overcome interspecies limitations of animal models or the loss of tissue architecture in in vitro models. However, analysis of tissue slices is often limited to histology. Here, we demonstrate that slices are also suitable for whole transcriptome sequencing and present a method for automated histochemistry of whole slices. Tumor and peritumoral tissue from a patient with glioblastoma was processed to slice cultures, which were treated with standard therapy including temozolomide and X-irradiation. Then, RNA sequencing and automated histochemistry were performed. RNA sequencing was successfully accomplished with a sequencing depth of 243 to 368 x 10⁶ reads per sample. Comparing tumor and peritumoral tissue, we identified 1888 genes significantly downregulated and 2382 genes upregulated in tumor. Treatment significantly downregulated 2017 genes, whereas 1399 genes were upregulated. Pathway analysis revealed changes in the expression profile of treated glioblastoma tissue pointing towards downregulated proliferation. This was confirmed by automated analysis of whole tissue slices stained for Ki67. In conclusion, we demonstrate that RNA sequencing of tissue slices is possible and that histochemical analysis of whole tissue slices can be automated which increases the usability of this preclinical model.

Prediction of Core Signaling Pathway by Using Diffusion- and Perfusion-based MRI Radiomics and Next-generation Sequencing in Isocitrate Dehydrogenase Wild-type Glioblastoma

Background Next-generation sequencing (NGS) enables highly sensitive cancer genomics analysis, but its clinical implications for therapeutic options from imaging-based prediction have been limited. Purpose To predict core signaling pathways in isocitrate dehydrogenase (IDH) wild-type glioblastoma by using diffusion and perfusion MRI radiomics and NGS. Materials and Methods The radiogenomics model was developed by using retrospective patients with glioma who underwent NGS and anatomic, diffusion-, and perfusion-weighted imaging between March 2017 and February 2019. For testing model performance in predicting core signaling pathway, patients with IDH wild-type glioblastoma from a retrospective analysis from a registry (ClinicalTrials.gov NCT02619890) were evaluated. Radiogenomic feature selection was performed by using t tests, least absolute shrinkage and selection operator penalization, and random forest. Combining radiogenomic features, age, and location, the performance of predicting receptor tyrosine kinase (RTK), tumor protein p53 (P53), and retinoblastoma 1 pathways was evaluated by using the area under the receiver operating characteristic curve (AUC). Results There were 120 patients (52 years ± 13 [standard deviation]; 61 women) who were evaluated. Eighty-five patients (51 years ± 13; 43 men) were in the training set and 35 patients with IDH wild-type glioblastoma (56 years ± 12; 19 women) were in the validation set. Radiogenomics model identified 71 features in the RTK, 17 features in P53, and 35 features in the retinoblastoma pathway. The combined model showed better performance than anatomic imaging-based prediction in the RTK (P = .03) and retinoblastoma (P = .03) and perfusion imaging-based prediction in the P53 pathway (P = .04) in the training set. AUC values of the combined model for the prediction of core signaling pathways were 0.88 (95% confidence interval [CI]: 0.74, 1) for RTK, 0.76 (95% CI: 0.59, 0.92) for P53, and 0.81 (95% CI: 0.64, 0.97) for retinoblastoma in the validation set. Conclusion A diffusion- and perfusion-weighted MRI radiomics model can help characterize core signaling pathways and potentially guide targeted therapy for isocitrate dehydrogenase wild-type glioblastoma. © RSNA, 2019 Online supplemental material is available for this article.

Quinoline-Conjugated Ruthenacarboranes: Toward Hybrid Drugs with a Dual Mode of Action

The role of autophagy in cancer is often complex, ranging from tumor-promoting to -suppressing effects. In this study, two novel hybrid molecules were designed, containing a ruthenacarborane fragment conjugated with a known modulator of autophagy, namely a quinoline derivative. The complex closo-[3-(η6 -p-cymene)-1-(quinolin-8-yl-acetate)-3,1,2-RuC2 B9 H10 ] (4) showed a dual mode of action against the LN229 (human glioblastoma) cell line, where it inhibited tumor-promoting autophagy, and strongly inhibited cell proliferation, de facto blocking cellular division. These results, together with the tendency to spontaneously form nanoparticles in aqueous solution, make complex 4 a very promising drug candidate for further studies in vivo, for the treatment of autophagy-prone glioblastomas.

Nuclear receptor 4A2 (NR4A2) is a druggable target for glioblastomas

INTRODUCTION

The orphan nuclear receptor 4A2 (NR4A2) has been extensively characterized in subcellular regions of the brain and is necessary for the function of dopaminergic neurons. The NR4A2 ligand, 1,1-bis (3¹-indoly1)-1-(p-chlorophenyl)methane (DIM-C-pPhCl) inhibits markers of neuroinflammation and degeneration in mouse models and in this study we investigated expression and function of NR4A2 in glioblastoma (GBM).

METHODS

Established and patient-derived cell lines were used as models and the expression and functions of NR4A2 were determined by western blots and NR4A2 gene silencing by antisense oligonucleotides respectively. Effects of NR4A2 knockdown and DIM-C-pPhCl on cell growth, induction of apoptosis (Annexin V Staining) and migration/invasion (Boyden chamber and spheroid invasion assay) and transactivation of NR4A2-regulated reporter genes were determined. Tumor growth was investigated in athymic nude mice bearing U87-MG cells as xenografts.

RESULTS

NR4A2 knockdown and DIM-C-pPhCl inhibited GBM cell and tumor growth, induced apoptosis and inhibited migration and invasion of GBM cells. DIM-C-pPhCl and related analogs also inhibited NR4A2-regulated transactivation (luciferase activity) confirming that DIM-C-pPhCl acts as an NR4A2 antagonist and blocks NR4A2-dependent pro-oncogenic responses in GBM.

CONCLUSION

We demonstrate for the first time that NR4A2 is pro-oncogenic in GBM and thus a potential druggable target for patients with tumors expressing this receptor. Moreover, our bis-indole-derived NR4A2 antagonists represent a novel class of anti-cancer agents with potential future clinical applications for treating GBM.

Dp71 Expression in Human Glioblastoma

BACKGROUND

Dp71 is the most abundant dystrophin (DMD) gene product in the nervous system. Mutation in the Dp71 coding region is associated with cognitive disturbances in Duchenne muscular dystrophy (DMD) patients, but the function of dystrophin Dp71 in tumor progression remains to be established. This study investigated Dp71 expression in glioblastoma, the most common and aggressive primary tumor of the central nervous system (CNS).

METHODS

Dp71 expression was analyzed by immunofluorescence, immunohistochemistry, RT-PCR, and immunoblotting in glioblastoma cell lines and cells isolated from human glioblastoma multiforme (GBM) bioptic specimens.

RESULTS

Dp71 isoform was expressed in normal human astrocytes (NHA) cell lines and decreased in glioblastoma cell lines and cells isolated from human glioblastoma multiforme bioptic specimens. Moreover, Dp71 was localized in the nucleus in normal cells, while it was localized into the cytoplasm of glioblastoma cells organized in clusters. We have shown, by double labeling, that Dp71 colocalizes with lamin B in normal astrocytes cells, confirming the roles of Dp71 and lamin B in maintaining nuclear architecture. Finally, we demonstrated that decreased Dp71 protein in cells isolated from human bioptic specimens was inversely correlated with the Ki-67 tumor proliferative index.

CONCLUSION

A decreased Dp71 expression is associated with cancer proliferation and poor prognosis in glioblastoma.

Mechanical Compression Regulates Brain Cancer Cell Migration Through MEK1/Erk1 Pathway Activation and GDF15 Expression

Mechanical compression is a common abnormality of brain tumors that has been shown to be responsible for the severe neurological defects of brain cancer patients representing a negative prognostic factor. Indeed, it is of note that patients that undergo resection exhibited higher survival rates than those subjected to biopsy only, suggesting that compressive forces generated during brain tumor growth play a key role in tumor progression. Despite the importance of mechanical compression in brain tumors, there is a lack of studies examining its direct effects on brain cancer cells and the mechanisms involved. In the present study, we used two brain cancer cell lines with distinct metastatic potential, the less aggressive H4 and the highly aggressive A172 cell lines, in order to study the effect of compression on their proliferative and migratory ability. Specifically, we used multicellular tumor spheroids (MCS) embedded in agarose matrix to show that compression strongly impaired their growth. Using mathematical modeling, we estimated the levels of compressive stress generated during the growth of brain MCS and then we applied the respective stress levels on brain cancer cell monolayers using our previously established transmembrane pressure device. By performing a scratch assay, we found that compression strongly induced the migration of the less aggressive H4 cells, while a less pronounced effect was observed for A172 cells. Analysis of the gene expression profile of both cell lines revealed that GDF15 and small GTPases are strongly regulated by mechanical compression, while GDF15 was further shown to be necessary for cells to migrate under compression. Through a phospho-proteomic screening, we further found that compressive stimulus is transmitted through the MEK1/Erk1 signaling pathway, which is also necessary for the migration of brain cancer cells. Finally, our results gave the first indication that GDF15 could regulate and being regulated by MEK1/Erk1 signaling pathway in order to facilitate the compression-induced brain cancer cell migration, rendering them along with small GTPases as potential targets for future anti-metastatic therapeutic innovations to treat brain tumors.

Tyrosine kinase Eph receptor A6 sensitizes glioma-initiating cells towards bone morphogenetic protein-induced apoptosis

Bone morphogenetic protein (BMP) signaling plays important roles in glioblastoma multiforme (GBM), a lethal form of brain tumor. BMP reduces GBM tumorigenicity through its differentiation‐ and apoptosis‐inducing effects on glioma‐initiating cells (GIC). However, some GIC do not respond to the tumor suppressive effects of BMP. Using a phosphoreceptor tyrosine kinase array, we found that EPHA6 (erythropoietin‐producing hepatocellular carcinoma receptor A6) phosphorylation was regulated by BMP‐2 signaling in some GIC. Analysis of The Cancer Genome Atlas showed that EPHA6 expression was lower in patients with GBM than in the normal brain, and that high EPHA6 expression was correlated with better prognosis. EPHA6 receptor increased the susceptibility of both sensitive and resistant GIC to BMP‐2‐induced apoptosis. The cooperative effect on apoptosis induction depended on the kinase activity of BMP type I receptor but was independent of EPHA6 kinase function. Overexpression of the EPHA6 receptor in GIC resulted in the formation of a protein complex of EPHA6 receptor and the BMP type I receptor ALK‐2, which was associated with BMP‐induced apoptosis in GIC. Intracranial injection of GIC into nude mice showed that gain‐of‐function of EPHA6 together with BMP‐2 pretreatment slowed GBM tumor progression in the mouse brain and promoted mouse survival. In summary, EPHA6 together with BMP‐2 signaling led to apoptotic cell death in GIC, and thus is a putative tumor suppressor in GBM.

GFAP alternative splicing regulates glioma cell-ECM interaction in a DUSP4-dependent manner

Gliomas are the most common primary brain tumors. Their highly invasive character and the heterogeneity of active oncogenic pathways within single tumors complicate the development of curative therapies and cause poor patient prognosis. Glioma cells express the intermediate filament protein glial fibrillary acidic protein (GFAP), and the level of its alternative splice variant GFAP-δ, relative to its canonical splice variant GFAP-α, is higher in grade IV compared with lower-grade and lower malignant glioma. In this study we show that a high GFAP-δ/α ratio induces the expression of the dual-specificity phosphatase 4 (DUSP4) in focal adhesions. By focusing on pathways up- and downstream of DUSP4 that are involved in the cell-extracellular matrix interaction, we show that a high GFAP-δ/α ratio equips glioma cells to better invade the brain. This study supports the hypothesis that glioma cells with a high GFAP-δ/α ratio are highly invasive and more malignant cells, thus making GFAP alternative splicing a potential therapeutic target.-Van Bodegraven, E. J., van Asperen, J. V., Sluijs, J. A., van Deursen, C. B. J., van Strien, M. E., Stassen, O. M. J. A., Robe, P. A. J., Hol, E. M. GFAP alternative splicing regulates glioma cell-ECM interaction in a DUSP4-dependent manner.

Current and Future Trends on Diagnosis and Prognosis of Glioblastoma: From Molecular Biology to Proteomics

Glioblastoma multiforme is the most aggressive malignant tumor of the central nervous system. Due to the absence of effective pharmacological and surgical treatments, the identification of early diagnostic and prognostic biomarkers is of key importance to improve the survival rate of patients and to develop new personalized treatments. On these bases, the aim of this review article is to summarize the current knowledge regarding the application of molecular biology and proteomics techniques for the identification of novel biomarkers through the analysis of different biological samples obtained from glioblastoma patients, including DNA, microRNAs, proteins, small molecules, circulating tumor cells, extracellular vesicles, etc. Both benefits and pitfalls of molecular biology and proteomics analyses are discussed, including the different mass spectrometry-based analytical techniques, highlighting how these investigation strategies are powerful tools to study the biology of glioblastoma, as well as to develop advanced methods for the management of this pathology.

The synthesis of a novel Crizotinib heptamethine cyanine dye conjugate that potentiates the cytostatic and cytotoxic effects of Crizotinib in patient-derived glioblastoma cell lines

We describe the synthesis of drug-dye conjugate 1 between anaplastic lymphoma kinase inhibitor Crizotinib and heptamethine cyanine dye IR-786. The drug-dye conjugate 1 was evaluated in three different patient-derived glioblastoma cell lines and showed potent cytotoxic activity with nanomolar potency (EC₅₀: 50.9 nM). We also demonstrate evidence for antiproliferative activity of 1 with single digit nanomolar potency (IC₅₀: 4.7 nM). Furthermore, the cytotoxic effects conveyed a dramatic, 110-fold improvement over Crizotinib. This improvement was even more pronounced (492-fold) when 1 was combined with Temozolomide, the standard drug for treatment for glioblastoma. This work lays the foundation for future exploration of similar tyrosine kinase inhibitor drug-dye conjugates for the treatment of glioblastoma.

Blockade of STAT3 Signaling Contributes to Anticancer Effect of 5-Acetyloxy-6,7,8,4'-Tetra-Methoxyflavone, a Tangeretin Derivative, on Human Glioblastoma Multiforme Cells

Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor with poor prognosis, largely due to resistance to current radiotherapy and Temozolomide chemotherapy. The constitutive activation of Signal Transducer and Activator of Transcription 3 (STAT3) is evidenced as a pivotal driver of GBM pathogenesis and therapy resistance, and hence, is a promising GBM drug target. 5-acetyloxy-6,7,8,4'-tetramethoxyflavone (5-AcTMF) is an acetylated derivative of Tangeretin which is known to exert anticancer effects on breast, colon, lung, and multiple myeloma; however, its effect on GBM remains elusive. Herein, we reported that 5-AcTMF suppressed the viability and clonogenicity along with inducing apoptosis in multiple human GBM cell lines. Mechanistic analyses further revealed that 5-AcTMF lowered the levels of Tyrosine 705-phosphorylated STAT3 (p-STAT3), a canonical marker of STAT3 activation, but also dampened p-STAT3 upregulation elicited by Interleukin-6. Notably, ectopic expression of dominant-active STAT3 impeded 5-AcTMF-induced suppression of viability and clonogenicity plus apoptosis induction in GBM cells, confirming the prerequisite of STAT3 blockage for the inhibitory action of 5-AcTMF on GBM cell survival and growth. Additionally, 5-AcTMF impaired the activation of STAT3 upstream kinase JAK2 but also downregulated antiapoptotic BCL-2 and BCL-xL in a STAT3-dependent manner. Moreover, the overexpression of either BCL-2 or BCL-xL abrogated 5-AcTMF-mediated viability reduction and apoptosis induction in GBM cells. Collectively, we, for the first time, revealed the anticancer effect of 5-AcTMF on GBM cells, which was executed via thwarting the JAK2-STAT3-BCL-2/BCL-xL signaling axis. Our findings further implicate the therapeutic potential of 5-AcTMF for GBM treatment.

Circulating monocytes and tumor-associated macrophages express recombined immunoglobulins in glioblastoma patients

BACKGROUND

Glioblastoma is the most common and malignant brain tumor in adults. Glioblastoma is usually fatal 12-15 months after diagnosis and the current possibilities in therapy are mostly only palliative. Therefore, new forms of diagnosis and therapy are urgently needed. Since tumor-associated macrophages are key players in tumor progression and survival there is large potential in investigating their immunological characteristics in glioblastoma patients. Recent evidence shows the expression of variable immunoglobulins and TCRαβ in subpopulations of monocytes, in vitro polarized macrophages and macrophages in the tumor microenvironment. We set out to investigate the immunoglobulin sequences of circulating monocytes and tumor-associated macrophages from glioblastoma patients to evaluate their potential as novel diagnostic or therapeutic targets.

RESULTS

We routinely find consistent expression of immunoglobulins in tumor-associated macrophages (TAM) and circulating monocytes from all glioblastoma patients analyzed in this study. However, the immunoglobulin repertoires of circulating monocytes and TAM are generally more restricted compared to B cells. Furthermore, the immunoglobulin expression in the macrophage populations negatively correlates with the tumor volume. Interestingly, the comparison of somatic mutations, V-chain usage, CDR3-length and the distribution of used heavy chain genes on the locus of chromosome 14 of the immunoglobulins from myeloid to B cells revealed virtually no differences.

CONCLUSIONS

The investigation of the immunoglobulin repertoires from TAM and circulating monocytes in glioblastoma-patients revealed a negative correlation to the tumor volume, which could not be detected in the immunoglobulin repertoires of the patients' B lymphocytes. Furthermore, the immunoglobulin repertoires of monocytes were more diverse than the repertoires of the macrophages in the tumor microenvironment from the same patients suggesting a tumor-specific immune response which could be advantageous for the use as diagnostic or therapeutic target.

Brain targeted delivery of anticancer drugs: prospective approach using solid lipid nanoparticles

A brain tumour is amongst most devastating and challenging condition to overcome with suitable treatment as the drug has to cross the blood-brain barrier (BBB) with several physiological barriers like opsonisation by the reticuloendothelial system. Presently various techniques such as surgical, chemotherapeutic agents, and radiotherapy techniques have performed to extend the lifespan of patients diagnosed with glioblastoma, which did not maximise the overall survival of patients with a tumour. Nanotechnology is relied upon to diminish the requirement for intrusive methods for conveyance of therapeutics to the central nervous system. Colloidal nanocarriers sizing range 1-1000 nm have been utilised to cross BBB delivers the drug at cell levels with enhanced bioavailability and reduced toxicity. However, solid lipid nanoparticles (SLNs) are considered a highly flexible carrier for more successful remedially in brain tumour. The treatment of a brain tumour via SLNs is gaining greater potency due to its inimitable size and lipidic nature. This review focuses and represents the current strategies of SLNs in the brain tumour treatment with appropriate techniques adopted are highlighted. Based on this review, the authors concluded that SLNs embrace exclusive promising lipidic nanocarrier that could be utilised to target a brain tumour effectively.

The kinase inhibitor SI113 induces autophagy and synergizes with quinacrine in hindering the growth of human glioblastoma multiforme cells

Background

Glioblastoma multiforme (GBM), due to its location, aggressiveness, heterogeneity and infiltrative growth, is characterized by an exceptionally dismal clinical outcome. The small molecule SI113, recently identified as a SGK1 inhibitor, has proven to be effective in restraining GBM growth in vitro and in vivo, showing also encouraging results when employed in combination with other antineoplastic drugs or radiotherapy. Our aim was to explore the pharmacological features of SI113 in GBM cells in order to elucidate the pivotal molecular pathways affected by the drug. Such knowledge would be of invaluable help in conceiving a rational offensive toward GBM.

Methods

We employed GBM cell lines, either established or primary (neurospheres), and used a Reverse-Phase Protein Arrays (RPPA) platform to assess the effect of SI113 upon 114 protein factors whose post-translational modifications are associated with activation or repression of specific signal transduction cascades.

Results

SI113 strongly affected the PI3K/mTOR pathway, evoking a pro-survival autophagic response in neurospheres. These results suggested the use of SI113 coupled, for maximum efficiency, with autophagy inhibitors. Indeed, the association of SI113 with an autophagy inhibitor, the antimalarial drug quinacrine, induced a strong synergistic effect in inhibiting GBM growth properties in all the cells tested, including neurospheres.

Conclusions

RPPA clearly identified the molecular pathways influenced by SI113 in GBM cells, highlighting their vulnerability when the drug was administered in association with autophagy inhibitors, providing a strong molecular rationale for testing SI113 in clinical trials in associative GBM therapy.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1212-1) contains supplementary material, which is available to authorized users.

Potential effects of nicotine on glioblastoma and chemoradiotherapy: a review

Introduction: Glioblastoma multiforme (GBM) has a poor prognosis despite maximal surgical resection with subsequent multi-modal radiation and chemotherapy. Use of tobacco products following diagnosis and during the period of treatment for non-neural tumors detrimentally affects treatment and prognosis. Approximately, 16-28% of patients with glioblastoma continue to smoke after diagnosis and during treatment. The literature is sparse for information-pertaining effects of smoking and nicotine on GBM treatment and prognosis. Areas covered: This review discusses cellular pathways involved in GBM progression that might be affected by nicotine, as well as how nicotine may contribute to resistance to treatment. Similarities of GBM pathways to those in non-neural tumors are investigated for potential effects by nicotine. English language papers were identified using PubMed, Medline and Scopus databases using a combination of keywords including but not limited to the following: nicotine, vaping, tobacco, e-cigarettes, smoking, vaping AND glioblastoma or brain cancer OR/AND temozolomide, carmustine, methotrexate, procarbazine, lomustine, vincristine, and neural tumor cell lines. Expert opinion: Understanding the impact of nicotine on treatment and resistance to chemotherapeutics should allow physicians to educate their patients with GBM with evidence-based recommendations about the effects of continuing to use nicotine-containing products after diagnosis and during treatment.

Amentoflavone Effectively Blocked the Tumor Progression of Glioblastoma via Suppression of ERK/NF- κ B Signaling Pathway

Glioblastoma is the most common primary malignant tumor of the central nervous system, with an annual incidence of 5.26 per 100000 people. The clinical outcome of standard therapy and the survival rate remain poor; therefore, there is an unmet need for a new strategy to treat this lethal disease. Although amentoflavone was known to have anticancer potential in various types of cancers, its antiglioblastoma ability and mechanism remain unrecognized. We demonstrated that amentoflavone may suppress glioblastoma invasion and migration by transwell assay. Moreover, we established NF- κ B reporter gene system and used that for verifying NF- κ B inhibition efficacy of amentoflavone on in vitro and in vivo studies. Here, we indicated that amentoflavone not only diminished NF- κ B activation, but also reduced NF- κ B-mediated downstream oncogenes expression, such as MMP-2, MMP-9, XIAP, cyclinD1 and VEGF, which was elucidated by Western blot and immunohistochemistry (IHC). Tumor growth inhibition and NF- κ B reduction was found in the amentoflavone treatment group, which was revealed by the glioblastoma-bearing animal model. In this study, we also used ERK inhibitor and NF- κ B inhibitor (QNZ) to confirm whether the beneficial result of amentoflavone on glioblastoma was mainly regulated by blockage of ERK/NF- κ B signaling. In summary, ERK/NF- κ B signaling pathway has a role in the inhibition of tumor growth by amentoflavone in glioblastoma.

Advancements of Annexin A1 in inflammation and tumorigenesis

Annexin A1 is a Ca²⁺-dependent phospholipid binding protein involved in a variety of pathophysiological processes. Accumulated evidence has indicated that Annexin A1 has important functions in cell proliferation, apoptosis, differentiation, metastasis, and inflammatory response. Moreover, the abnormal expression of Annexin A1 is closely related to the occurrence and development of tumors. In this review article, we focus on the structure and function of Annexin A1 protein, especially the recent evidence of Annexin A1 in the pathophysiological role of inflammatory and cancer. This summary will be very important for further investigation of the pathophysiological role of Annexin A1 and for the development of novel therapeutics of inflammatory and cancer based on targeting Annexin A1 protein.

Multifaceted Functional Role of Semaphorins in Glioblastoma

Glioblastoma (GBM) is the most malignant tumor type affecting the adult central nervous system. Despite advances in therapy, the prognosis for patients with GBM remains poor, with a median survival of about 15 months. To date, few treatment options are available and recent trials based on the molecular targeting of some of the GBM hallmark pathways (e.g., angiogenesis) have not produced any significant improvement in overall survival. The urgent need to develop more efficacious targeted therapies has led to a better molecular characterization of GBM, revealing an emerging role of semaphorins in GBM progression. Semphorins are a wide group of membrane-bound and secreted proteins, originally identified as axon guidance cues, signaling through their receptors, neuropilins, and plexins. A number of semaphorin signals involved in the control of axonal growth and navigation during development have been found to furthermore participate in crosstalk with different dysfunctional GBM pathways, controlling tumor cell proliferation, migration, and invasion, as well as tumor angiogenesis or immune response. In this review, we summarize the regulatory activities mediated by semaphorins and their receptors on the oncogenic pathways implicated in GBM growth and invasive/metastatic progression.

The Role of SVZ Stem Cells in Glioblastoma

As most common primary brain cancer, glioblastoma is also the most aggressive and malignant form of cancer in the adult central nervous system. Glioblastomas are genetic and transcriptional heterogeneous tumors, which in spite of intensive research are poorly understood. Over the years conventional therapies failed to affect a cure, resulting in low survival rates of affected patients. To improve the clinical outcome, an important approach is to identify the cells of origin. One potential source for these are neural stem cells (NSCs) located in the subventricular zone, which is one of two niches in the adult nervous system where NSCs with the capacity of self-renewal and proliferation reside. These cells normally give rise to neuronal as well as glial progenitor cells. This review summarizes current findings about links between NSCs and cancer stem cells in glioblastoma and discusses current therapeutic approaches, which arise as a result of identifying the cell of origin in glioblastoma.

Discovery of Small-Molecule Inhibitors of the HSP90-Calcineurin-NFAT Pathway against Glioblastoma

Glioblastoma (GBM) is among the most common and malignant types of primary brain tumors in adults, with a dismal prognosis. Although alkylating agents such as temozolomide are widely applied as the first-line treatment for GBM, they often cause chemoresistance and remain ineffective with recurrent GBM. Alternative therapeutics against GBM are urgently needed in the clinic. We report herein the discovery of a class of inhibitors (YZ129 and its derivatives) of the calcineurin-NFAT pathway that exhibited potent anti-tumor activity against GBM. YZ129-induced GBM cell-cycle arrest at the G2/M phase promoted apoptosis and inhibited tumor cell proliferation and migration. At the molecular level, YZ129 directly engaged HSP90 to antagonize its chaperoning effect on calcineurin to abrogate NFAT nuclear translocation, and also suppressed other proto-oncogenic pathways including hypoxia, glycolysis, and the PI3K/AKT/mTOR signaling axis. Our data highlight the potential for targeting the cancer-promoting HSP90 chaperone network to treat GBM.

Signal transduction pathways and resistance to targeted therapies in glioma

Although surgical techniques and adjuvant therapies have undergone progressive development for decades, the therapeutic outcomes for treating glioblastoma (GBM) remain poor. The main reasons for the poor prognosis of gliomas are that limited tumor tissue that can be resected (to preserve brain functions) and that residual tumors are often resistant to irradiation and chemotherapy. Therefore, overcoming the resistance of residual tumors against adjuvant therapy is urgently needed for glioma treatment. Recent large cohort studies of genetic alterations in GBM demonstrated that both genetic information and intracellular molecular signaling are networked in gliomas and that such information may help clarify which molecules or signals serve essential roles in resistance against radiation or chemotherapy, highlighting them as potential novel therapeutic targets against refractory gliomas. In this review, we summarize the current understanding of molecular networks that govern glioma biology, mainly based on cohort studies or recent evidence, with a focus on how intracellular signaling molecules in gliomas associate with each other and regulate refractoriness against current therapy.

Receptor-Targeted Glial Brain Tumor Therapies

Among primary brain tumors, malignant gliomas are notably difficult to manage. The higher-grade tumors represent an unmet need in medicine. There have been extensive efforts to implement receptor-targeted therapeutic approaches directed against gliomas. These approaches include immunotherapies, such as vaccines, adoptive immunotherapy, and passive immunotherapy. Targeted cytotoxic radio energy and pro-drug activation have been designed specifically for brain tumors. The field of targeting through receptors progressed significantly with the discovery of an interleukin 13 receptor alpha 2 (IL-13RA2) as a tumor-associated receptor over-expressed in most patients with glioblastoma (GBM) but not in normal brain. IL-13RA2 has been exploited in novel experimental therapies with very encouraging clinical responses. Other receptors are specifically over-expressed in many patients with GBM, such as EphA2 and EphA3 receptors, among others. These findings are important in view of the heterogeneity of GBM tumors and multiple tumor compartments responsible for tumor progression and resistance to therapies. The combined targeting of multiple receptors in different tumor compartments should be a preferred way to design novel receptor-targeted therapeutic approaches in gliomas.

Mutational Landscape of Secondary Glioblastoma Guides MET-Targeted Trial in Brain Tumor

Low-grade gliomas almost invariably progress into secondary glioblastoma (sGBM) with limited therapeutic option and poorly understood mechanism. By studying the mutational landscape of 188 sGBMs, we find significant enrichment of TP53 mutations, somatic hypermutation, MET-exon-14-skipping (METex14), PTPRZ1-MET (ZM) fusions, and MET amplification. Strikingly, METex14 frequently co-occurs with ZM fusion and is present in ∼14% of cases with significantly worse prognosis. Subsequent studies show that METex14 promotes glioma progression by prolonging MET activity. Furthermore, we describe a MET kinase inhibitor, PLB-1001, that demonstrates remarkable potency in selectively inhibiting MET-altered tumor cells in preclinical models. Importantly, this compound also shows blood-brain barrier permeability and is subsequently applied in a phase I clinical trial that enrolls MET-altered chemo-resistant glioma patients. Encouragingly, PLB-1001 achieves partial response in at least two advanced sGBM patients with rarely significant side effects, underscoring the clinical potential for precisely treating gliomas using this therapy.

GSK461364A, a Polo-Like Kinase-1 Inhibitor Encapsulated in Polymeric Nanoparticles for the Treatment of Glioblastoma Multiforme (GBM)

Glioblastoma Multiforme (GBM) is a common primary brain cancer with a poor prognosis and a median survival of less than 14 months. Current modes of treatment are associated with deleterious side effects that reduce the life span of the patients. Nanomedicine enables site-specific delivery of active pharmaceutical ingredients and facilitates entrapment inside the tumor. Polo-like kinase 1 (PLK-1) inhibitors have shown promising results in tumor cells. GSK461364A (GSK) is one such targeted inhibitor with reported toxicity issues in phase 1 clinical trials. We have demonstrated in our study that the action of GSK is time dependent across all concentrations. There is a distinct 15−20% decrease in cell viability via apoptosis in U87-MG cells dosed with GSK at low concentrations (within the nanomolar and lower micromolar range) compared to higher concentrations of the drug. Additionally, we have confirmed that PLGA-PEG nanoparticles (NPs) containing GSK have shown significant reduction in cell viability of tumor cells compared to their free equivalents. Thus, this polymeric nanoconstruct encapsulating GSK can be effective even at low concentrations and could improve the effectiveness of the drug while reducing side effects at the lower effective dose. This is the first study to report a PLK-1 inhibitor (GSK) encapsulated in a nanocarrier for cancer applications.

Targeted Theranostic Nanoparticles for Brain Tumor Treatment

The poor prognosis and rapid recurrence of glioblastoma (GB) are associated to its fast-growing process and invasive nature, which make difficult the complete removal of the cancer infiltrated tissues. Additionally, GB heterogeneity within and between patients demands a patient-focused method of treatment. Thus, the implementation of nanotechnology is an attractive approach considering all anatomic issues of GB, since it will potentially improve brain drug distribution, due to the interaction between the blood⁻brain barrier and nanoparticles (NPs). In recent years, theranostic techniques have also been proposed and regarded as promising. NPs are advantageous for this application, due to their respective size, easy surface modification and versatility to integrate multiple functional components in one system. The design of nanoparticles focused on therapeutic and diagnostic applications has increased exponentially for the treatment of cancer. This dual approach helps to understand the location of the tumor tissue, the biodistribution of nanoparticles, the progress and efficacy of the treatment, and is highly useful for personalized medicine-based therapeutic interventions. To improve theranostic approaches, different active strategies can be used to modulate the surface of the nanotheranostic particle, including surface markers, proteins, drugs or genes, and take advantage of the characteristics of the microenvironment using stimuli responsive triggers. This review focuses on the different strategies to improve the GB treatment, describing some cell surface markers and their ligands, and reports some strategies, and their efficacy, used in the current research.

Role of extracellular matrix and microenvironment in regulation of tumor growth and LAR-mediated invasion in glioblastoma

The cellular dispersion and therapeutic control of glioblastoma, the most aggressive type of primary brain cancer, depends critically on the migration patterns after surgery and intracellular responses of the individual cancer cells in response to external biochemical cues in the microenvironment. Recent studies have shown that miR-451 regulates downstream molecules including AMPK/CAB39/MARK and mTOR to determine the balance between rapid proliferation and invasion in response to metabolic stress in the harsh tumor microenvironment. Surgical removal of the main tumor is inevitably followed by recurrence of the tumor due to inaccessibility of dispersed tumor cells in normal brain tissue. In order to address this complex process of cell proliferation and invasion and its response to conventional treatment, we propose a mathematical model that analyzes the intracellular dynamics of the miR-451-AMPK- mTOR-cell cycle signaling pathway within a cell. The model identifies a key mechanism underlying the molecular switches between proliferative phase and migratory phase in response to metabolic stress in response to fluctuating glucose levels. We show how up- or down-regulation of components in these pathways affects the key cellular decision to infiltrate or proliferate in a complex microenvironment in the absence and presence of time delays and stochastic noise. Glycosylated chondroitin sulfate proteoglycans (CSPGs), a major component of the extracellular matrix (ECM) in the brain, contribute to the physical structure of the local brain microenvironment but also induce or inhibit glioma invasion by regulating the dynamics of the CSPG receptor LAR as well as the spatiotemporal activation status of resident astrocytes and tumor-associated microglia. Using a multi-scale mathematical model, we investigate a CSPG-induced switch between invasive and non-invasive tumors through the coordination of ECM-cell adhesion and dynamic changes in stromal cells. We show that the CSPG-rich microenvironment is associated with non-invasive tumor lesions through LAR-CSGAG binding while the absence of glycosylated CSPGs induce the critical glioma invasion. We illustrate how high molecular weight CSPGs can regulate the exodus of local reactive astrocytes from the main tumor lesion, leading to encapsulation of non-invasive tumor and inhibition of tumor invasion. These different CSPG conditions also change the spatial profiles of ramified and activated microglia. The complex distribution of CSPGs in the tumor microenvironment can determine the nonlinear invasion behaviors of glioma cells, which suggests the need for careful therapeutic strategies.

The special stemness functions of Tbx3 in stem cells and cancer development

The T-box factors belong to an ancient protein family, which comprises a cluster of evolutionarily-conserved transcription factors that regulate gene expression and that are crucial to embryonic development. T-box transcription factor 3 (Tbx3) is a member of this family, is expressed in some tissues, and is a key regulator in many critical organs, including the heart, mammary gland, and limbs. Overexpression of Tbx3 is associated with a number of cancers, including head and neck squamous cell carcinoma, gastric, breast, ovary, cervical, pancreatic, bladder and liver cancers, as well as melanoma. Tbx3 promotes tumor development by modulating cell proliferation, tumor formation, metastasis, cell survival and drug resistance. Moreover, there is strong evidence that Tbx3 regulates stem cell maintenance by controlling stem cell self-renewal and differentiation. Verification of the upstream regulatory factors and potential molecular mechanism of Tbx3, being able to explain the function of Tbx3 in carcinogenic effects and stem cell maintenance, will make a valuable contribution to stem cell and cancer research. This review provides an insight into the current research on Tbx3 and explores the significance of Tbx3 in stem cells and tumorigenesis.

Elucidating the microRNA-203 specific biological processes in glioblastoma cells from comprehensive RNA-sequencing transcriptome profiling

Glioblastoma (GBM) is the most common primary malignant intracranial adult brain tumor. Allelic deletion on chromosome 14q plays an essential role in GBM pathogenesis, and this chromosome 14q site was thought to harbor multiple tumor suppressor genes associated with GBM, a region that also encodes microRNA-203 (miR-203). This study was conducted to identify whole transcriptome profile changes associated with miR-203 expression by high-throughput RNA sequencing. Enrichment analyses for gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that miR-203 expression had a strong, negative effect on a number of fundamental and interconnected biological processes involved in cell growth and proliferation. The biological processes mostly influenced were p53 signaling pathway, FoxO signaling pathway, DNA replication, cell cycle, MAPK signaling pathway, and apoptosis. In total, 847 upregulated and 345 downregulated differentially expressed genes were identified in control versus miR-203 expressing glioma cells. After GO enrichment, the downregulated differentially expressed genes such as BCL2, SPARC were found to be mainly enriched in cell cycle regulation and apoptosis processes, whereas the upregulated differentially expressed genes such as CCND1, E2F1 were involved in the DNA replication and cell cycle regulation. We also performed miR-203 target analysis and found BCL2, AKT, SPARC, ROBO1, c-JUN, PDGFA, and CREB were predicted target of miR-203 and miR-203 expression suppressed the protein and mRNA levels of these target genes by western blotting and qRT-PCR analysis. Moreover, co-transfection experiments using a luciferase-based reporter assay demonstrated that miR-203 directly regulated BCL-2 expression and BCL-2 overexpression suppressed miR-203 mediated glioma cell apoptosis. These results indicate that overexpression of miR-203 coordinately regulates several oncogenic pathways in GBM.

Discovery and Therapeutic Exploitation of Mechanisms of Resistance to MET Inhibitors in Glioblastoma

PURPOSE

Glioblastoma (GBM) is the most common and most lethal primary malignant brain tumor. The receptor tyrosine kinase MET is frequently upregulated or overactivated in GBM. Although clinically applicable MET inhibitors have been developed, resistance to single modality anti-MET drugs frequently occurs, rendering these agents ineffective. We aimed to determine the mechanisms of MET inhibitor resistance in GBM and use the acquired information to develop novel therapeutic approaches to overcome resistance.Experimental Design: We investigated two clinically applicable MET inhibitors: crizotinib, an ATP-competitive small molecule inhibitor of MET, and onartuzumab, a monovalent monoclonal antibody that binds to the extracellular domain of the MET receptor. We developed new MET inhibitor-resistant cells lines and animal models and used reverse phase protein arrays (RPPA) and functional assays to uncover the compensatory pathways in MET inhibitor-resistant GBM.

RESULTS

We identified critical proteins that were altered in MET inhibitor-resistant GBM including mTOR, FGFR1, EGFR, STAT3, and COX-2. Simultaneous inhibition of MET and one of these upregulated proteins led to increased cell death and inhibition of cell proliferation in resistant cells compared with either agent alone. In addition, in vivo treatment of mice bearing MET-resistant orthotopic xenografts with COX-2 or FGFR pharmacological inhibitors in combination with MET inhibitor restored sensitivity to MET inhibition and significantly inhibited tumor growth.

CONCLUSIONS

These data uncover the molecular basis of adaptive resistance to MET inhibitors and identify new FDA-approved multidrug therapeutic combinations that can overcome resistance.