Glioblastoma Cellular Origin and the Firework Pattern of Cancer Genesis from the Subventricular Zone

Comparison of the biological characteristics of glioblastoma tumorspheres obtained from fresh and cryopreserved glioblastoma tissues

PURPOSE

Glioblastoma (GBM) is the most common and aggressive primary brain tumor. Human GBM tumorspheres (TS) are essential for preclinical drug screening and establishing patient-derived xenograft (PDX) models, but their derivation is often limited to fresh tissue. Whether TS from cryopreserved tissues retain comparable molecular and biological properties to those from fresh tissues remains underexplored. We hypothesized that TS from cryopreserved tissues could provide a reliable alternative for TS derivation, thereby expanding accessibility for GBM research.

METHODS

TS isolation rates were compared across 39 primary GBM samples. Tumor tissues collected during surgical resection were divided into two groups: one processed immediately as fresh tissue, and the other cryopreserved for 1 month before processing. Gene expression profiling via RNA sequencing and biological comparisons, including cell proliferation, neuroglial differentiation, stemness, invasiveness, and responsiveness to radiation and temozolomide, were performed on three matched TS samples from each group. Tumorigenesis was also assessed using PDX models.

RESULTS

TS were successfully isolated from 64.1% of fresh and 58.9% of cryopreserved tissues. Gene expression profiling revealed similar expression patterns in TS derived from both tissue types, despite variations in cancer subtypes. Cell proliferation, neuroglial differentiation, stemness, or invasiveness rates did not differ significantly between TS derived from fresh and cryopreserved tissues. All three GBM TS exhibited comparable responsiveness to temozolomide and radiation, as well as similar tumorigenic potential in the PDX models.

CONCLUSION

These findings suggest an alternative method for isolating TS when immediate processing is not feasible, offering a time-independent approach for GBM research.

Synergistic combination of perphenazine and temozolomide suppresses patient-derived glioblastoma tumorspheres

BACKGROUND

Glioblastoma (GBM), a primary malignant brain tumor, has a poor prognosis, even with standard treatments such as radiotherapy and chemotherapy. In this study, we explored the anticancer effects of the synergistic combination of perphenazine (PER), a dopamine receptor D2/3 (DRD2/3) antagonist, and temozolomide (TMZ), a standard treatment for GBM, in patient-derived human GBM tumorspheres (TSs).

METHODS

The biological effects of the combination of PER and TMZ in GBM TSs were assessed by measuring cell viability, ATP, stemness, invasiveness, and apoptosis. Changes in protein and mRNA expression were analyzed using western blotting and RNA sequencing. Co-administration of PER and TMZ was evaluated in vivo using a mouse orthotopic xenograft model.

RESULTS

The Severance dataset showed that DRD2 and DRD3 expressions were higher in tumor tissues than in the tumor-free cortex of patients with GBM. DRD2/3 knockout by CRISPR/Cas9 in patient-derived human GBM TSs inhibited cell growth and ATP production. The combined treatment with PER and TMZ resulted in superior effects on cell viability and ATP assays compared to those in single treatment groups. Flow cytometry, western blotting, and RNA sequencing confirmed elevated apoptosis in GBM TSs following combination treatment. Additionally, the combination of PER and TMZ downregulated the expression of protein and mRNA associated with stemness and invasiveness. In vivo evaluation showed that combining PER and TMZ extended the survival period of the mouse orthotopic xenograft model.

CONCLUSIONS

The synergistic combination of PER and TMZ has potential as a novel combination treatment strategy for GBM.

Disruption of bioenergetics enhances the radio-sensitivity of patient-derived glioblastoma tumorspheres

BACKGROUND

Despite available treatment approaches, including surgical resection along with chemotherapy and radiotherapy, glioblastoma (GBM), the most prevalent primary brain tumor, remains associated with a grim prognosis. Although radiotherapy is central to GBM treatment, its combination with bioenergetics regulators has not been validated in clinical practice. Here, we hypothesized that bioenergetics regulators can enhance the radio-sensitivity of GBM tumorspheres (TSs).

METHODS

Gene expression profiles of GBM patient-derived TSs were obtained through microarray and RNA-seq. In vitro treatment efficacy was assessed using clonogenic assay, 3D invasion assay, neurosphere formation assay, and flow cytometry. Protein expression was measured via western blot, and γH2AX foci were detected via immunofluorescence. In vivo efficacy was confirmed in an orthotopic xenograft model.

RESULTS

Based on radiation response-associated gene expression, GBM TSs were classified into high- or low-radioresistant groups. Among the five bioenergetics regulators, the pentose phosphate pathway inhibitor DHEA and the glycolysis inhibitor 2-DG notably enhanced the efficacy of ionizing radiation (IR) efficacy in vitro, reducing the survival fraction, stemness, and invasiveness in high- and low-radioresistant TSs. Combination with 2-DG further stimulated IR-induced DNA damage response and apoptosis in low-radioresistant GBM TSs. RNA-seq analysis revealed a downregulation of bioenergetics- and cell cycle-associated genes, whereas extracellular matrix- and cell adhesion-associated genes were enhanced by combined IR and 2-DG treatment. This therapeutic regimen extended survival and diminished tumor size in mouse xenograft models.

CONCLUSIONS

Our data suggest that combination with bioenergetics regulator 2-DG enhances the radio-sensitivity of GBM TSs, highlighting the clinical potential of this combined regimen.

Association between the Anatomical Location of Glioblastoma and Its Evaluation with Clinical Considerations: A Systematic Review and Meta-Analysis

Background: Glioblastoma is a primary malignant brain tumor; it is aggressive with a high degree of malignancy and unfavorable prognosis and is the most common type of malignant brain tumor. Glioblastomas can be located in the brain, cerebellum, brainstem, and spinal cord, originating from glial cells, particularly astrocytes. Methods: The databases MEDLINE, Scopus, Web of Science, Google Scholar, and CINAHL were researched up to January 2024. Two authors independently performed the search, study selection, and data extraction. Methodological quality was evaluated with an assurance tool for anatomical studies (AQUA). The statistical mean, standard deviation, and difference of means calculated with the Student's t-test for presence between hemispheres and presence in the frontal and temporal lobes were analyzed. Results: A total of 123 studies met the established selection criteria, with a total of 6224 patients. In relation to the mean, GBM between hemispheres had a mean of 33.36 (SD 58.00) in the right hemisphere and a mean of 34.70 (SD 65.07) in the left hemisphere, due to the difference in averages between hemispheres. There were no statistically significant differences, p = 0.35. For the comparison between the presence of GBM in the frontal lobe and the temporal lobe, there was a mean in the frontal lobe of 23.23 (SD 40.03), while in the temporal lobe, the mean was 22.05 (SD 43.50), and for the difference in means between the frontal lobe and the temporal lobe, there was no statistically significant difference for the presence of GBM, p = 0.178. Conclusions: We believe that before a treatment, it will always be correct to know where the GBM is located and how it behaves clinically, in order to generate correct conservative or surgical treatment guidelines for each patient. We believe that more detailed studies are also needed to show why GBM is associated more with some regions than others, despite the brain structure being homologous to other regions in which GMB occurs less frequently, which is why knowing its predominant presence in brain regions is very important.

Classification of IDH wild-type glioblastoma tumorspheres into low- and high-invasion groups based on their transcriptional program

BACKGROUND

Glioblastoma (GBM), one of the most lethal tumors, exhibits a highly infiltrative phenotype. Here, we identified transcription factors (TFs) that collectively modulate invasion-related genes in GBM.

METHODS

The invasiveness of tumorspheres (TSs) were quantified using collagen-based 3D invasion assays. TF activities were quantified by enrichment analysis using GBM transcriptome, and confirmed by cell-magnified analysis of proteome imaging. Invasion-associated TFs were knocked down using siRNA or shRNA, and TSs were orthotopically implanted into mice.

RESULTS

After classifying 23 patient-derived GBM TSs into low- and high-invasion groups, we identified active TFs in each group-PCBP1 for low invasion, and STAT3 and SRF for high invasion. Knockdown of these TFs reversed the phenotype and invasion-associated-marker expression of GBM TSs. Notably, MRI revealed consistent patterns of invasiveness between TSs and the originating tumors, with an association between high invasiveness and poor prognosis. Compared to controls, mice implanted with STAT3- or SRF-downregulated GBM TSs showed reduced normal tissue infiltration and tumor growth, and prolonged survival, indicating a therapeutic response.

CONCLUSIONS

Our integrative transcriptome analysis revealed three invasion-associated TFs in GBM. Based on the relationship among the transcriptional program, invasive phenotype, and prognosis, we suggest these TFs as potential targets for GBM therapy.

C5α secreted by tumor mesenchymal stem-like cells mediates resistance to 5-aminolevulinic acid-based photodynamic therapy against glioblastoma tumorspheres

PURPOSE

Advancements in photodynamic diagnosis (PDD) and photodynamic therapy (PDT) as a standard care in cancer therapy have been limited. This study is aimed to investigate the clinical availability of 5-aminolevulinic acid (5-ALA)-based PDD and PDT in glioblastoma (GBM) patient-derived tumorspheres (TSs) and mouse orthotopic xenograft model.

METHODS

PDT was performed using a 635 nm light-emitting diode (LED). Transcriptome profiles were obtained from microarray data. For knockdown of C5α, siRNA was transfected into tumor mesenchymal stem-like cells (tMSLCs). The invasiveness of TSs was quantified using collagen-based 3D invasion assays.

RESULTS

Treatment with 1 mM 5 ALA induced distinct protoporphyrin IX (PpIX) fluorescence in GBM TSs, but not in non-tumor cells or tissues, including tMSLCs. These observations were negatively correlated with the expression levels of FECH, which catalyzes the conversion of accumulated PpIX to heme. Furthermore, the 5-ALA-treated GBM TSs were sensitive to PDT, thereby significantly decreasing cell viability and invasiveness. Notably, the effects of PDT were abolished by culturing TSs with tMSLC-conditioned media. Transcriptome analysis revealed diverse tMSLC-secreted chemokines, including C5α, and their correlations with the expression of stemness- or mesenchymal transition-associated genes. By adding or inhibiting C5α, we confirmed that acquired resistance to PDT was induced via tMSLC-secreted C5α.

CONCLUSIONS

Our results show substantial therapeutic effects of 5-ALA-based PDT on GBM TSs, suggesting C5α as a key molecule responsible for PDT resistance. These findings could trigger PDT as a standard clinical modality for the treatment of GBM.

Targeting the neural stem cells in subventricular zone for the treatment of glioblastoma: an update from preclinical evidence to clinical interventions

BACKGROUND

Glioblastoma is one of the most common and aggressive adult brain tumors. The conventional treatment strategy, surgery combined with chemoradiotherapy, did not change the fact that the recurrence rate was high and the survival rate was low. Over the years, accumulating evidence has shown that the subventricular zone has an important role in the recurrence and treatment resistance of glioblastoma. The human adult subventricular zone contains neural stem cells and glioma stem cells that are probably a part of reason for therapy resistance and recurrence of glioblastoma.

MAIN BODY

Over the years, both bench and bedside evidences strongly support the view that the presence of neural stem cells and glioma stem cells in the subventricular zone may be the crucial factor of recurrence of glioblastoma after conventional therapy. It emphasizes the necessity to explore new therapy strategies with the aim to target subventricular zone to eradicate neural stem cells or glioma stem cells. In this review, we summarize the recent preclinical and clinical advances in targeting neural stem cells in the subventricular zone for glioblastoma treatment, and clarify the prospects and challenges in clinical application.

CONCLUSIONS

Although there remain unresolved issues, current advances provide us with a lot of evidence that targeting the neural stem cells and glioma stem cells in subventricular zone may have the potential to solve the dilemma of glioblastoma recurrence and treatment resistance.

Regulation of Cell Plasticity by Bromodomain and Extraterminal Domain (BET) Proteins: A New Perspective in Glioblastoma Therapy

BET proteins are a family of multifunctional epigenetic readers, mainly involved in transcriptional regulation through chromatin modelling. Transcriptome handling ability of BET proteins suggests a key role in the modulation of cell plasticity, both in fate decision and in lineage commitment during embryonic development and in pathogenic conditions, including cancerogenesis. Glioblastoma is the most aggressive form of glioma, characterized by a very poor prognosis despite the application of a multimodal therapy. Recently, new insights are emerging about the glioblastoma cellular origin, leading to the hypothesis that several putative mechanisms occur during gliomagenesis. Interestingly, epigenome dysregulation associated with loss of cellular identity and functions are emerging as crucial features of glioblastoma pathogenesis. Therefore, the emerging roles of BET protein in glioblastoma onco-biology and the compelling demand for more effective therapeutic strategies suggest that BET family members could be promising targets for translational breakthroughs in glioblastoma treatment. Primarily, “Reprogramming Therapy”, which is aimed at reverting the malignant phenotype, is now considered a promising strategy for GBM therapy.

Mesenchymal Stem-Like Cells Derived from the Ventricle More Effectively Enhance Invasiveness of Glioblastoma Than Those Derived from the Tumor

PURPOSE

Glioblastoma (GBM) is one of the most lethal human tumors with a highly infiltrative phenotype. Our previous studies showed that GBM originates in the subventricular zone, and that tumor-derived mesenchymal stem-like cells (tMSLCs) promote the invasiveness of GBM tumorspheres (TSs). Here, we extend these studies in terms of ventricles using several types of GBM patient-derived cells.

MATERIALS AND METHODS

The invasiveness of GBM TSs and ventricle spheres (VSs) were quantified via collagen-based 3D invasion assays. Gene expression profiles were obtained from microarray data. A mouse orthotopic xenograft model was used for in vivo experiments.

RESULTS

After molecular and functional characterization of ventricle-derived mesenchymal stem-like cells (vMSLCs), we investigated the effects of these cells on the invasiveness of GBM TSs. We found that vMSLC-conditioned media (CM) significantly accelerated the invasiveness of GBM TSs and VSs, compared to the control and even tMSLC-CM. Transcriptome analyses revealed that vMSLC secreted significantly higher levels of several invasiveness-associated cytokines. Moreover, differentially expressed genes between vMSLCs and tMSLCs were enriched for migration, adhesion, and chemotaxis-related gene sets, providing a mechanistic basis for vMSLC-induced invasion of GBM TSs. In vivo experiments using a mouse orthotopic xenograft model confirmed vMSLC-induced increases in the invasiveness of GBM TSs.

CONCLUSION

Although vMSLCs are non-tumorigenic, this study adds to our understanding of how GBM cells acquire infiltrative features by vMSLCs, which are present in the region where GBM genesis originates.

Dual inhibition of CPT1A and G6PD suppresses glioblastoma tumorspheres

PURPOSE

Limited treatment options are currently available for glioblastoma (GBM), an extremely lethal type of brain cancer. For a variety of tumor types, bioenergetic deprivation through inhibition of cancer-specific metabolic pathways has proven to be an effective therapeutic strategy. Here, we evaluated the therapeutic effects and underlying mechanisms of dual inhibition of carnitine palmitoyltransferase 1A (CPT1A) and glucose-6-phosphate dehydrogenase (G6PD) critical for fatty acid oxidation (FAO) and the pentose phosphate pathway (PPP), respectively, against GBM tumorspheres (TSs).

METHODS

Therapeutic efficacy against GBM TSs was determined by assessing cell viability, neurosphere formation, and 3D invasion. Liquid chromatography-mass spectrometry (LC-MS) and RNA sequencing were employed for metabolite and gene expression profiling, respectively. Anticancer efficacy in vivo was examined using an orthotopic xenograft model.

RESULTS

CPT1A and G6PD were highly expressed in GBM tumor tissues. Notably, siRNA-mediated knockdown of both genes led to reduced viability, ATP levels, and expression of genes associated with stemness and invasiveness. Similar results were obtained upon combined treatment with etomoxir and dehydroepiandrosterone (DHEA). Transcriptome analyses further confirmed these results. Data from LC-MS analysis showed that this treatment regimen induced a considerable reduction in the levels of metabolites associated with the TCA cycle and PPP. Additionally, the combination of etomoxir and DHEA inhibited tumor growth and extended survival in orthotopic xenograft model mice.

CONCLUSION

Our collective findings support the utility of dual suppression of CPT1A and G6PD with selective inhibitors, etomoxir and DHEA, as an efficacious therapeutic approach for GBM.

Oncolytic viruses as a promising therapeutic strategy against the detrimental health impacts of air pollution: The case of glioblastoma multiforme

Human livelihood highly depends on applying different sources of energy whose utilization is associated with air pollution. On the other hand, air pollution may be associated with glioblastoma multiforme (GBM) development. Unlike other environmental causes of cancer (e.g., irradiation), air pollution cannot efficiently be controlled by geographical borders, regulations, and policies. The unavoidable exposure to air pollution can modify cancer incidence and mortality. GBM treatment with chemotherapy or even its surgical removal has proven insufficient (100% recurrence rate; patient's survival mean of 15 months; 90% fatality within five years) due to glioma infiltrative and migratory capacities. Given the barrage of attention and research investments currently plowed into next-generation cancer therapy, oncolytic viruses are perhaps the most vigorously pursued. Provision of an insight into the current state of the research and future direction is essential for stimulating new ideas with the potentials of filling research gaps. This review manuscript aims to overview types of brain cancer, their burden, and different causative agents. It also describes why air pollution is becoming a concerning factor. The different opinions on the association of air pollution with brain cancer are reviewed. It tries to address the significant controversy in this field by hypothesizing the air-pollution-brain-cancer association via inflammation and atopic conditions. The last section of this review deals with the oncolytic viruses, which have been used in, or are still under clinical trials for GBM treatment. Engineered adenoviruses (i.e., DNX-2401, DNX-2440, CRAd8-S-pk7 loaded Neural stem cells), herpes simplex virus type 1 (i.e., HSV-1 C134, HSV-1 rQNestin34.5v.2, HSV-1 G207, HSV-1 M032), measles virus (i.e., MV-CEA), parvovirus (i.e., ParvOryx), poliovirus (i.e., Poliovirus PVSRIPO), reovirus (i.e., pelareorep), moloney murine leukemia virus (i.e., Toca 511 vector), and vaccinia virus (i.e., vaccinia virus TG6002) as possible life-changing alleviations for GBM have been discussed. To the best of our knowledge, this review is the first review that comprehensively discusses both (i) the negative/positive association of air pollution with GBM; and (ii) the application of oncolytic viruses for GBM, including the most recent advances and clinical trials. It is also the first review that addresses the controversies over air pollution and brain cancer association. We believe that the article will significantly appeal to a broad readership of virologists, oncologists, neurologists, environmentalists, and those who work in the field of (bio)energy. Policymakers may also use it to establish better health policies and regulations about air pollution and (bio)fuels exploration, production, and consumption.

Etomoxir, a carnitine palmitoyltransferase 1 inhibitor, combined with temozolomide reduces stemness and invasiveness in patient-derived glioblastoma tumorspheres

Introduction

The importance of fatty acid oxidation (FAO) in the bioenergetics of glioblastoma (GBM) is being realized. Etomoxir (ETO), a carnitine palmitoyltransferase 1 (CPT1) inhibitor exerts cytotoxic effects in GBM, which involve interrupting the FAO pathway. We hypothesized that FAO inhibition could affect the outcomes of current standard temozolomide (TMZ) chemotherapy against GBM.

Methods

The FAO-related gene expression was compared between GBM and the tumor-free cortex. Using four different GBM tumorspheres (TSs), the effects of ETO and/or TMZ was analyzed on cell viability, tricarboxylate (TCA) cycle intermediates and adenosine triphosphate (ATP) production to assess metabolic changes. Alterations in tumor stemness, invasiveness, and associated transcriptional changes were also measured. Mouse orthotopic xenograft model was used to elucidate the combinatory effect of TMZ and ETO.

Results

GBM tissues exhibited overexpression of FAO-related genes, especially CPT1A, compared to the tumor-free cortex. The combined use of ETO and TMZ further inhibited TCA cycle and ATP production than single uses. This combination treatment showed superior suppression effects compared to treatment with individual agents on the viability, stemness, and invasiveness of GBM TSs, as well as better downregulation of FAO-related gene expression. The results of in vivo study showed prolonged survival outcomes in the combination treatment group.

Conclusion

ETO, an FAO inhibitor, causes a lethal energy reduction in the GBM TSs. When used in combination with TMZ, ETO effectively reduces GBM cell stemness and invasiveness and further improves survival. These results suggest a potential novel treatment option for GBM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02731-7.

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.

A lignan from Alnus japonica inhibits glioblastoma tumorspheres by suppression of FOXM1

Forkhead Box M1 (FOXM1) is known to regulate cell proliferation, apoptosis and tumorigenesis. The lignan, (-)-(2R,3R)-1,4-O-diferuloylsecoisolariciresinol (DFS), from Alnus japonica has shown anti-cancer effects against colon cancer cells by suppressing FOXM1. The present study hypothesized that DFS can have anti-cancer effects against glioblastoma (GBM) tumorspheres (TSs). Immunoprecipitation and luciferase reporter assays were performed to evaluate the ability of DFS to suppress nuclear translocation of β-catenin through β-catenin/FOXM1 binding. DFS-pretreated GBM TSs were evaluated to assess the ability of DFS to inhibit GBM TSs and their transcriptional profiles. The in vivo efficacy was examined in orthotopic xenograft models of GBM. Expression of FOXM1 was higher in GBM than in normal tissues. DFS-induced FOXM1 protein degradation blocked β-catenin translocation into the nucleus and consequently suppressed downstream target genes of FOXM1 pathways. DFS inhibited cell viability and ATP levels, while increasing apoptosis, and it reduced tumorsphere formation and the invasiveness of GBM TSs. And DFS reduced the activities of transcription factors related to tumorigenesis, stemness, and invasiveness. DFS significantly inhibited tumor growth and prolonged the survival rate of mice in orthotopic xenograft models of GBM. It suggests that DFS inhibits the proliferation of GBM TSs by suppressing FOXM1. DFS may be a potential therapeutic agent to treat GBM.

Patterns of recurrence according to the extent of resection in patients with IDH-wild-type glioblastoma: a retrospective study

OBJECTIVE

In glioblastoma (GBM) patients, controlling the microenvironment around the tumor using various treatment modalities, including surgical intervention, is essential in determining the outcome of treatment. This study was conducted to elucidate whether recurrence patterns differ according to the extent of resection (EOR) and whether this difference affects prognosis.

METHODS

This single-center study included 358 eligible patients with histologically confirmed isocitrate dehydrogenase (IDH)-wild-type GBM from November 1, 2005, to December 31, 2018. Patients were assigned to one of three separate groups according to EOR: supratotal resection (SupTR), gross-total resection (GTR), and subtotal resection (STR) groups. The patterns of recurrence were classified as local, marginal, and distant based on the range of radiation. The relationship between EOR and recurrence pattern was statistically analyzed.

RESULTS

Observed tumor recurrence rates for each group were as follows: SupTR group, 63.4%; GTR group, 75.3%; and STR group, 80.5% (p = 0.072). Statistically significant differences in patterns of recurrences among groups were observed with respect to local recurrence (SupTR, 57.7%; GTR, 76.0%; STR, 82.8%; p = 0.036) and distant recurrence (SupTR, 50.0%; GTR, 30.1%; STR, 23.2%; p = 0.028). Marginal recurrence showed no statistical difference between groups. Both overall survival and progression-free survival were significantly increased in the SupTR group compared with the STR and GTR groups (p < 0.0001).

CONCLUSIONS

In this study, the authors investigated the association between EOR and patterns of recurrence in patients with IDH-wild-type GBM. The findings not only show that recurrence patterns differ according to EOR but also provide clinical evidence supporting the hypothesized mechanism by which distant recurrence occurs.

A novel biguanide (IM1761065) inhibits bioenergetics of glioblastoma tumorspheres

PURPOSE

Glioblastoma (GBM) is a rapidly growing tumor in the central nervous system with altered metabolism. Depleting the bioenergetics of tumors with biguanides have been suggested as an effective therapeutic approach for treating GBMs. The purpose of this study was to determine the effects of IM1761065, a novel biguanide with improved pharmacokinetics, on GBM-tumorspheres (TSs).

METHODS

The biological activities of IM1761065 on GBM-TSs, including their effects on viability, ATP levels, cell cycle, stemness, invasive properties, and transcriptomes were examined. The in vivo efficacy of IM1761065 was tested in a mouse orthotopic xenograft model.

RESULTS

IM1761065 decreased the viability and ATP levels of GBM-TSs in a dose-dependent manner, and reduced basal and spare respiratory capacity in patient-derived GBM-TS, as measured by the oxygen consumption rate. Sphere formation, expression of stemness-related proteins, and invasive capacity of GBM-TSs were also significantly suppressed by IM1761065. A gene-ontology comparison of IM1761065-treated groups showed that the expression levels of stemness-related, epithelial mesenchymal transition-related, and mitochondrial complex I genes were also significantly downregulated by IM1761065. An orthotopic xenograft mouse model showed decreased bioluminescence in IM1761065-treated cell-injected mice at 5 weeks. IM1761065-treated group showed longer survival than the control group (P = 0.0289, log-rank test).

CONCLUSION

IM1761065 is a potent inhibitor of oxidative phosphorylation. The inhibitory effect of IM1761065 on the bioenergetics of GBM-TS suggests that this novel compound could be used as a new drug for the treatment of GBM.

Influence of the Amount of Fresh Specimen on the Isolation of Tumor Mesenchymal Stem-Like Cells from High-Grade Glioma

PURPOSE

A critical indicator of the overall survival of patients with high-grade glioma is the successful isolation of tumor mesenchymal stem-like cells (tMSLCs), which play important roles in glioma progression. However, attempts to isolate tMSLCs from surgical specimens have not always been successful, and the reasons for this remain unclear. Considering that the amount of surgical high-grade glioma specimens varies, we hypothesized that larger surgical specimens would be better for tMSLC isolation.

MATERIALS AND METHODS

We assessed 51 fresh, high-grade glioma specimens and divided them into two groups according to the success or failure of tMSLC isolation. The success of tMSLC isolation was confirmed by plastic adherence, presenting antigens, tri-lineage differentiation, and non-tumorigenicity. Differences in characteristics between the two groups were tested using independent two sample t-tests, chi-square tests, or Kaplan-Meier survival analysis.

RESULTS

The mean specimen weights of the groups differed from each other (tMSLC-negative group: 469.9±341.9 mg, tMSLC positive group: 546.7±618.9 mg), but the difference was not statistically significant. The optimal cut-off value of specimen weight was 180 mg, and the area under the curve value was 0.599.

CONCLUSION

Our results suggested a minimum criterion for specimen collection, and found that the specimen amount was not deeply related to tMSLC detection. Collectively, our findings imply that the ability to isolate tMSLCs is determined by factors other than the specimen amount.

Fluorescence-Guided Surgery for High-Grade Gliomas: State of the Art and New Perspectives

High-grade gliomas are aggressive tumors that require multimodal management and gross total resection is considered to be the first crucial step of treatment. Because of their infiltrative nature, intraoperative differentiation of neoplastic tissue from normal parenchyma can be challenging. For these reasons, in the recent years, neurosurgeons have increasingly performed this surgery under the guidance of tissue fluorescence. Sodium fluoresceine and 5-aminolevulinic acid represent the 2 main compounds that allow real-time identification of residual malignant tissue and have been associated with improved gross total resection and radiological outcomes. Though presenting different profiles of sensitivity and specificity and further investigations concerning cost-effectiveness are need, Sodium fluoresceine, 5-aminolevulinic acid and new phluorophores, such as Indocyanine green, represent some of the most important tools in the neurosurgeon’s hands to achieve gross total resection.

Combinatorial Therapeutic Effect of Inhibitors of Aldehyde Dehydrogenase and Mitochondrial Complex I, and the Chemotherapeutic Drug, Temozolomide against Glioblastoma Tumorspheres

Resident cancer cells with stem cell-like features induce drug tolerance, facilitating survival of glioblastoma (GBM). We previously showed that strategies targeting tumor bioenergetics present a novel emerging avenue for treatment of GBM. The objective of this study was to enhance the therapeutic effects of dual inhibition of tumor bioenergetics by combination of gossypol, an aldehyde dehydrogenase inhibitor, and phenformin, a biguanide compound that depletes oxidative phosphorylation, with the chemotherapeutic drug, temozolomide (TMZ), to block proliferation, stemness, and invasiveness of GBM tumorspheres (TSs). Combination therapy with gossypol, phenformin, and TMZ induced a significant reduction in ATP levels, cell viability, stemness, and invasiveness compared to TMZ monotherapy and dual therapy with gossypol and phenformin. Analysis of differentially expressed genes revealed up-regulation of genes involved in programmed cell death, autophagy, and protein metabolism and down-regulation of those associated with cell metabolism, cycle, and adhesion. Combination of TMZ with dual inhibitors of tumor bioenergetics may, therefore, present an effective strategy against GBM by enhancing therapeutic effects through multiple mechanisms of action.

Co-expression of cancer driver genes: IDH-wildtype glioblastoma-derived tumorspheres

BACKGROUND

Driver genes of GBM may be crucial for the onset of isocitrate dehydrogenase (IDH)-wildtype (WT) glioblastoma (GBM). However, it is still unknown whether the genes are expressed in the identical cluster of cells. Here, we have examined the gene expression patterns of GBM tissues and patient-derived tumorspheres (TSs) and aimed to find a progression-related gene.

METHODS

We retrospectively collected primary IDH-WT GBM tissue samples (n = 58) and tumor-free cortical tissue samples (control, n = 20). TSs are isolated from the IDH-WT GBM tissue with B27 neurobasal medium. Associations among the driver genes were explored in the bulk tissue, bulk cell, and a single cell RNAsequencing techniques (scRNAseq) considering the alteration status of TP53, PTEN, EGFR, and TERT promoter as well as MGMT promoter methylation. Transcriptomic perturbation by temozolomide (TMZ) was examined in the two TSs.

RESULTS

We comprehensively compared the gene expression of the known driver genes as well as MGMT, PTPRZ1, or IDH1. Bulk RNAseq databases of the primary GBM tissue revealed a significant association between TERT and TP53 (p < 0.001, R = 0.28) and its association increased in the recurrent tumor (p  < 0.001, R = 0.86). TSs reflected the tissue-level patterns of association between the two genes (p < 0.01, R = 0.59, n = 20). A scRNAseq data of a TS revealed the TERT and TP53 expressing cells are in a same single cell cluster. The driver-enriched cluster dominantly expressed the glioma-associated long noncoding RNAs. Most of the driver-associated genes were downregulated after TMZ except IGFBP5.

CONCLUSIONS

GBM tissue level expression patterns of EGFR, TERT, PTEN, IDH1, PTPRZ1, and MGMT are observed in the GBM TSs. The driver gene-associated cluster of the GBM single cells were enriched with the glioma-associated long noncoding RNAs.

Ambient carbon monoxide exposure and elevated risk of mortality in the glioblastoma patients: A double-cohort retrospective observational study

An increasing number of studies indicate air pollutants infiltrate into the brain. We aimed to find the association of cumulative air pollution exposure in the main body of primary brain tumor: glioblastoma (GBM). In this double-cohort, retrospective analysis study with a protocol, we compared the health effect of air pollution on the GBM patients from the SEER (Surveillance, Epidemiology, and End Results Program) in 27 U.S. counties from 10 states and GBM patients of Severance cohort of Korea. From 2000 to 2015, 10621 GBM patients of the SEER were individually evaluated for the cumulative average exposure for each pollutant, and 9444 (88.9%) mortality events were reported. From 2011 to 2018, 398 GBM patients of the Severance with the same protocol showed 259 (65.1%) mortality events. The multi-pollutant models show that the association level of risk with CO is increased in the SEER (HR 1.252; 95% CI 1.141-1.373) with an increasing linear trend of relative death rate in the spline curve. The Severance GBM data showed such a statistically significant result of the health impact of CO on GBM patients. The overall survival gain of the less exposure group against CO was 2 and 3 months in the two cohorts. Perioperative exposure to CO may increase the risk of shorter survival of GBM patients of the SEER and the Severance cohort.

Combined effects of niclosamide and temozolomide against human glioblastoma tumorspheres

PURPOSE

Glioblastoma (GBM) is the most aggressive type of brain tumor and has poor survival outcomes, even after a combination of surgery, radiotherapy, and chemotherapy. Temozolomide is the only agent that has been shown to be effective against GBM, suggesting that combination of temozolomide with other agents may be more effective. Niclosamide, an FDA approved anthelmintic agent, has shown anti-cancer effects against human colon, breast, prostate cancers as well as GBM. However, the efficacy of the combination of niclosamide with temozolomide against GBM tumorspheres (TSs) has not been determined. We hypothesized that the combined treatment could effectively suppress GBM TSs.

METHODS

GBM TSs (TS15-88, GSC11) were treated with niclosamide and/or temozolomide. Combined effects of two drugs were evaluated by measuring viability, neurosphere formation, and 3D-invasion in collagen matrix. Transcriptional profiles of GBM TS were analyzed using RNA sequencing. In vivo anticancer efficacy of combined drugs was tested in a mouse orthotopic xenograft model.

RESULTS

Combination treatment of niclosamide and temozolomide significantly inhibited the cell viability, stemness, and invasive properties of GBM TSs. This combined treatment significantly down-regulated the expression of epithelial mesenchymal transition-related markers, Zeb1, N-cadherin, and β-catenin. The combined treatment also significantly decreased tumor growth in orthotopic xenograft models.

CONCLUSION

The combination of niclosamide and temozolomide effectively decreased the stemness and invasive properties of GBM TSs, suggesting that this regimen may be therapeutically effective in treating patients with GBM.