Glioblastoma multiforme: overview of current treatment and future perspectives

RAPID resistance to BET inhibitors is mediated by FGFR1 in glioblastoma

Bromodomain and extra-terminal domain (BET) proteins are therapeutic targets in several cancers including the most common malignant adult brain tumor glioblastoma (GBM). Multiple small molecule inhibitors of BET proteins have been utilized in preclinical and clinical studies. Unfortunately, BET inhibitors have not shown efficacy in clinical trials enrolling GBM patients. One possible reason for this may stem from resistance mechanisms that arise after prolonged treatment within a clinical setting. However, the mechanisms and timeframe of resistance to BET inhibitors in GBM is not known. To identify the temporal order of resistance mechanisms in GBM we performed quantitative proteomics using multiplex-inhibitor bead mass spectrometry and demonstrated that intrinsic resistance to BET inhibitors in GBM treatment occurs rapidly within hours and involves the fibroblast growth factor receptor 1 (FGFR1) protein. Additionally, small molecule inhibition of BET proteins and FGFR1 simultaneously induces synergy in reducing GBM tumor growth in vitro and in vivo. Further, FGFR1 knockdown synergizes with BET inhibitor mediated reduction of GBM cell proliferation. Collectively, our studies suggest that co-targeting BET and FGFR1 may dampen resistance mechanisms to yield a clinical response in GBM.

Non-coding RNAs as Key Regulators of the Notch Signaling Pathway in Glioblastoma: Diagnostic, Prognostic, and Therapeutic Targets

Glioblastoma multiforme (GBM) is a highly invasive brain malignancy originating from astrocytes, accounting for approximately 30% of central nervous system malignancies. Despite advancements in therapeutic strategies including surgery, chemotherapy, and radiopharmaceutical drugs, the prognosis for GBM patients remains dismal. The aggressive nature of GBM necessitates the identification of molecular targets and the exploration of effective treatments to inhibit its proliferation. The Notch signaling pathway, which plays a critical role in cellular homeostasis, becomes deregulated in GBM, leading to increased expression of pathway target genes such as MYC, Hes1, and Hey1, thereby promoting cellular proliferation and differentiation. Recent research has highlighted the regulatory role of non-coding RNAs (ncRNAs) in modulating Notch signaling by targeting critical mRNA expression at the post-transcriptional or transcriptional levels. Specifically, various types of ncRNAs, including long non-coding RNAs (lncRNAs) and microRNAs (miRNAs), have been shown to control multiple target genes and significantly contribute to the carcinogenesis of GBM. Furthermore, these ncRNAs hold promise as prognostic and predictive markers for GBM. This review aims to summarize the latest studies investigating the regulatory effects of ncRNAs on the Notch signaling pathway in GBM.

Sphingosine-1-Phosphate Recruits Macrophages and Microglia and Induces a Pro-Tumorigenic Phenotype That Favors Glioma Progression

Glioblastoma is the most aggressive brain tumor in adults. Treatment failure is predominantly caused by its high invasiveness and its ability to induce a supportive microenvironment. As part of this, a major role for tumor-associated macrophages/microglia (TAMs) in glioblastoma development was recognized. Phospholipids are important players in various fundamental biological processes, including tumor-stroma crosstalk, and the bioactive lipid sphingosine-1-phosphate (S1P) has been linked to glioblastoma cell proliferation, invasion, and survival. Despite the urgent need for better therapeutic approaches, novel strategies targeting sphingolipids in glioblastoma are still poorly explored. Here, we showed that higher amounts of S1P secreted by glioma cells are responsible for an active recruitment of TAMs, mediated by S1P receptor (S1PR) signaling through the modulation of Rac1/RhoA. This resulted in increased infiltration of TAMs in the tumor, which, in turn, triggered their pro-tumorigenic phenotype through the inhibition of NFkB-mediated inflammation. Gene set enrichment analyses showed that such an anti-inflammatory microenvironment correlated with shorter survival of glioblastoma patients. Inhibition of S1P restored a pro-inflammatory phenotype in TAMs and resulted in increased survival of tumor-bearing mice. Taken together, our results establish a crucial role for S1P in fine-tuning the crosstalk between glioma and infiltrating TAMs, thus pointing to the S1P-S1PR axis as an attractive target for glioma treatment.

Effectiveness of Flattening-Filter-Free versus Flattened Beams in V79 and Glioblastoma Patient-Derived Stem-like Cells

Literature data on the administration of conventional high-dose beams with (FF) or without flattening filters (FFF) show conflicting results on biological effects at the cellular level. To contribute to this field, we irradiated V79 Chinese hamster lung fibroblasts and two patient-derived glioblastoma stem-like cell lines (GSCs-named #1 and #83) using a clinical 10 MV accelerator with FF (at 4 Gy/min) and FFF (at two dose rates 4 and 24 Gy/min). Cell killing and DNA damage induction, determined using the γ-H2AX assay, and gene expression were studied. No significant differences in the early survival of V79 cells were observed as a function of dose rates and FF or FFF beams, while a trend of reduction in late survival was observed at the highest dose rate with the FFF beam. GSCs showed similar survival levels as a function of dose rates, both delivered in the FFF regimen. The amount of DNA damage measured for both dose rates after 2 h was much higher in line #1 than in line #83, with statistically significant differences between the two dose rates only in line #83. The gene expression analysis of the two GSC lines indicates gene signatures mimicking the prognosis of glioblastoma (GBM) patients derived from a public database. Overall, the results support the current use of FFF and highlight the possibility of identifying patients with candidate gene signatures that could benefit from irradiation with FFF beams at a high dose rate.

Epigenetic basis for PARP mutagenesis in glioblastoma: A review

Several modifications in the glioblastoma genes are caused by epigenetic modifications, which are crucial in appropriate developmental processes such as self-renewal and destiny determination of neural stem cells. Poly (ADP-ribose)polymerase (PARP) is an essential cofactor involved in DNA repair as well as several other cellular functions such as transcription and chromatin shape modification. Inhibiting PARP has evolved for triggering cell damage in cancerous cells when paired with certain other anticancer drugs including temozolomide (TMZ). PARP1 is involved with in base excision repair (BER) pathway, however its functionality differs across types of tumours. Epigenomics as well as chromosomal statistics have contributed to the growth of main subgroups of glioma, which serve as foundation for the categorization of central nervous system (CNS) tumours as well as a unique classification based only on DNA methylation information, which demonstrates extraordinary diagnostic accuracy. Unfortunately, not all patients respond to PARP inhibitors (PARPi), and there is no way to anticipate who will and who will not. In this field, PARPi are one of the innovative medicines currently being explored. As a result, cancer cells that also have a homologous recombination defect become fatal synthetically. As well as preparing the tumour microenvironment for immunotherapy, PARPi may enhance the lethal effects of chemotherapy and radiotherapy. This article analyzes the justification and clinical evidence for PARPi in glioma to offer potential therapeutic approaches. Despite the effectiveness of these targeted drugs, researchers have looked into a number of resistance mechanisms as well as the growing usage of PARPi in clinical practice for the treatment of various malignancies.

Dexamethasone and compliance affect TTFields efficacy to glioblastoma patients: a systematic review and meta-analysis

TTFields is a novel treating modality of glioblastoma (GBM) which can significantly prolong the overall survival (OS) of newly diagnosed or recurrent glioblastoma. Some researchers have revealed that a variety of factors can affect the efficacy of TTFields. So, we review the available literature about the influencing factors on efficacy of TTFields and then choose two experimentally supported factors: the dose of dexamethasone and compliance of TTFields to perform a meta-analysis. The PubMed, Embase, and the Cochrane Library are searched. Five articles are identified between 2014 and 2017. Three articles are about the compliance of TTFields. Two articles are about the dose of dexamethasone. The Newcastle-Ottawa Quality Assessment Scale (NOS) is used as an assessment tool to evaluate the methodological quality of all included trials. The scale’s range varies from 0 to 9 stars. According to the Cochrane Handbook for Systematic Reviews of Interventions, articles are graded in six items to evaluate the risk of bias. Two reviewers rate the studies independently and the final decision is reached by consensus.

Our data shows that the median OS is conspicuously longer in the TTFields group in which the dose of dexamethasone is ≤ 4.1 mg, WMD = 9.23 [95% CI 5.69–12.78]; P < 0.05). And the patients whose compliance of TTFields treatment ≥ 75% (≥ 18 h per day) have a significant lower overall survival risk than the patients whose compliance of TTFields treatment < 75% (HR = 0.57 [95% CI 0.46–0.70]; P < 0.00001).TTFields is a safe and efficient novel treatment modality. The dose of dexamethasone ≤ 4.1 mg of TTFields treatment and the compliance of TTFields treatment ≥ 75%, ≥ 18 h per day are beneficial to the prognosis of the glioblastoma patients.

Posaconazole inhibits the stemness of cancer stem-like cells by inducing autophagy and suppressing the Wnt/β-catenin/survivin signaling pathway in glioblastoma

Posaconazole (POS) has been reported to present potential antitumor activity for glioblastoma (GBM). However, its molecular mechanisms remain unclear. In this study, we found that POS has potent cytotoxicity and inhibits cell viability and proliferation in GBM. In addition, we adopted a sphere formation assay to detect the self-renewal capacity, performed western blotting to measure cancer stem-like cells (CSCs) marker proteins (CD133, SOX2, Nanog and Oct4) and applied flow cytometry to monitor the subpopulation of CD144⁺/CD33⁺ cells, and the results all demonstrated that POS can remarkably weaken CSCs stemness. Furthermore, western blotting, immunoflurescence, transmission electron microscopy and acridine orange staining were performed to detect autophagy-related proteins (LC3, SQSTM1, Beclin 1 and Atg5), count the numbers of endogenous LC3 puncta, visually observe the ultrastructural morphology of autophagosomes and judge the formation of acidic vesicular organelles, respectively, and the results validated that POS promotes autophagy induction. Importantly, the suppressive effect of POS on CSCs stemness was partially relieved when autophagy was blocked by the autophagy inhibitor chloroquine (CQ) or Atg5 shRNA. Bioinformatic techniques, including weighted gene coexpression network analysis (WGCNA), gene set difference analysis (GSVA) and KEGG pathway analysis, combined with experimental validations showed that survivin, which is implicated in both autophagy and the stem cell index, is one of the target proteins of POS and that POS weakens CSCs stemness via suppressing the Wnt/β-catenin signaling pathway in GBM. Besides, POS-induced autophagy and the Wnt/β-catenin signaling pathway are negative regulators for each other. Finally, the antitumor activity of POS was confirmed in GBM xenograft models in vivo. Consistent with the in vitro conclusions, POS upregulated the expression of LC3 and decreased the expression of CD133, survivin and β-catenin, as shown by the immunohistochemistry analysis. In summary, this work provides an experimental foundation for exploiting POS as a CSCs-targeting antitumor drug for GBM treatment.

Senescence Is the Main Trait Induced by Temozolomide in Glioblastoma Cells

First-line drug in the treatment of glioblastoma, the most severe brain cancer, is temozolomide (TMZ), a DNA-methylating agent that induces the critical damage O6-methylguanine (O6MeG). This lesion is cytotoxic through the generation of mismatch repair-mediated DNA double-strand breaks (DSBs), which trigger apoptotic pathways. Previously, we showed that O6MeG also induces cellular senescence (CSEN). Here, we show that TMZ-induced CSEN is a late response which has similar kinetics to apoptosis, but at a fourfold higher level. CSEN cells show a high amount of DSBs, which are located outside of telomeres, a high level of ROS and oxidized DNA damage (8-oxo-guanine), and sustained activation of the DNA damage response and histone methylation. Despite the presence of DSBs, CSEN cells are capable of repairing radiation-induced DSBs. Glioblastoma cells that acquired resistance to TMZ became simultaneously resistant to TMZ-induced CSEN. Using a Tet-On glioblastoma cell system, we show that upregulation of MGMT immediately after TMZ completely abrogated apoptosis and CSEN, while induction of MGMT long-term (>72 h) after TMZ did not reduce apoptosis and CSEN. Furthermore, upregulation of MGMT in the senescent cell population had no impact on the survival of senescent cells, indicating that O6MeG is required for induction, but not for maintenance of the senescent state. We further show that, in recurrent GBM specimens, a significantly higher level of DSBs and CSEN-associated histone H3K27me3 was observed than in the corresponding primary tumors. Overall, the data indicate that CSEN is a key node induced in GBM following chemotherapy.

OCT-Guided Surgery for Gliomas: Current Concept and Future Perspectives

Optical coherence tomography (OCT) has been recently suggested as a promising method to obtain in vivo and real-time high-resolution images of tissue structure in brain tumor surgery. This review focuses on the basics of OCT imaging, types of OCT images and currently suggested OCT scanner devices and the results of their application in neurosurgery. OCT can assist in achieving intraoperative precision identification of tumor infiltration within surrounding brain parenchyma by using qualitative or quantitative OCT image analysis of scanned tissue. OCT is able to identify tumorous tissue and blood vessels detection during stereotactic biopsy procedures. The combination of OCT with traditional imaging such as MRI, ultrasound and 5-ALA fluorescence has the potential to increase the safety and accuracy of the resection. OCT can improve the extent of resection by offering the direct visualization of tumor with cellular resolution when using microscopic OCT contact probes. The theranostic implementation of OCT as a part of intelligent optical diagnosis and automated lesion localization and ablation could achieve high precision, automation and intelligence in brain tumor surgery. We present this review for the increase of knowledge and formation of critical opinion in the field of OCT implementation in brain tumor surgery.

miR-138-5p Inhibits the Growth and Invasion of Glioma Cells by Regulating WEE1

Background. Accumulating evidence has demonstrated the role of differentially expressed miRNAs in glioma progression. Our previous bioinformatics analyses revealed a role of miR-138-5p in glioma. miR-138-5p was decreased in various tumors, and He et al. found that miR-138-5p had an inhibitory effect on glioma cells in 2021. However, the role of miR-138-5p in the development of glioma and the underlying mechanism is unknown. In this study, we explored whether miR-138-5p affects the biology of glioma by regulating WEE1 expression. Methods. miR-138-5p and WEE1 G2 checkpoint kinase (WEE1) RNA and protein expression levels in glioma tissues were detected with qRT-PCR and western blotting, respectively. The effects of miR-138-5p and WEE1 on glioma cell migration and invasion were investigated using Transwell assays. CCK-8 assay was used to measure the effects of miR-138-5p and WEE1 on glioma cell proliferation. The mortality of glioma cells transfected with miR-138-5p and WEE1 was measured with flow cytometry. The relationship between miR-138-5p and WEE1 was explored using a luciferase reporter analysis. Results. Functional studies indicated that overexpression of miR-138-5p suppressed cell proliferation, migration, and invasion and promoted death in glioma cell lines. WEE1 was identified as a target of miR-138-5p, and overexpression of miR-138-5p significantly suppressed the levels of WEE1. Moreover, reintroduction of WEE1 partially abrogated miR-138-5p-induced suppression of motility and invasion in glioma cells. Conclusion. The low expression of miR-138-5p in glioma suggests a tumor suppressor role for this miRNA. miR-138-5p suppresses glioma progression by regulating WEE1. These data provide new insights into the molecular mechanism of glioma.

PIM1 Inhibition Affects Glioblastoma Stem Cell Behavior and Kills Glioblastoma Stem-like Cells

Despite comprehensive therapy and extensive research, glioblastoma (GBM) still represents the most aggressive brain tumor in adults. Glioma stem cells (GSCs) are thought to play a major role in tumor progression and resistance of GBM cells to radiochemotherapy. The PIM1 kinase has become a focus in cancer research. We have previously demonstrated that PIM1 is involved in survival of GBM cells and in GBM growth in a mouse model. However, little is known about the importance of PIM1 in cancer stem cells. Here, we report on the role of PIM1 in GBM stem cell behavior and killing. PIM1 inhibition negatively regulates the protein expression of the stem cell markers CD133 and Nestin in GBM cells (LN-18, U-87 MG). In contrast, CD44 and the astrocytic differentiation marker GFAP were up-regulated. Furthermore, PIM1 expression was increased in neurospheres as a model of GBM stem-like cells. Treatment of neurospheres with PIM1 inhibitors (TCS PIM1-1, Quercetagetin, and LY294002) diminished the cell viability associated with reduced DNA synthesis rate, increased caspase 3 activity, decreased PCNA protein expression, and reduced neurosphere formation. Our results indicate that PIM1 affects the glioblastoma stem cell behavior, and its inhibition kills glioblastoma stem-like cells, pointing to PIM1 targeting as a potential anti-glioblastoma therapy.

Molecular Dosimetry of Temozolomide: Quantification of Critical Lesions, Correlation to Cell Death Responses, and Threshold Doses

Temozolomide (TMZ) is a DNA-methylating agent used in cancer chemotherapy, notably for glioblastoma multiforme (GBM), where it is applied as a front-line drug. One of the DNA alkylation products of TMZ is the minor lesion O⁶ -methylguanine (O⁶ MeG), which is responsible for nearly all genotoxic, cytotoxic, and cytostatic effects induced in the low-dose range relevant for cancer therapy. Here, we addressed the question of how many O⁶ MeG adducts are required to elicit cytotoxic responses. Adduct quantification revealed that O⁶ MeG increases linearly with dose. The same was observed for DNA double-strand breaks (DSB) and p53ser15. Regarding apoptosis, hockeystick modeling indicated a possible threshold for A172 cells at 2.5 μmol/L TMZ, whereas for LN229 cells no threshold was detected. Cellular senescence, which is the main cellular response, also increased linearly, without a threshold. Using a dose of 20 μmol/L, which is achievable in a therapeutic setting, we determined that 14,000 adducts give rise to 32 DSBs (γH2AX foci) in A172 cells. This leads to 12% cell death and 35% of cells entering senescence. In LN229 cells, 20 μmol/L TMZ induced 20,600 O⁶ MeG adducts, 66 DSBs (γH2AX foci), 24% apoptosis, and 52% senescence. The linear dose response and the genotoxic and cytotoxic effects observed at therapeutically relevant dose levels make it very likely that the TMZ target concentration triggers a significant cytotoxic and cytostatic effect in vivo Despite a linear increase in the O⁶ MeG adduct level, DSBs, and p53 activation, the low curative effect of TMZ results presumably from the low rate of apoptosis compared to senescence.

Adjusting the Molecular Clock: The Importance of Circadian Rhythms in the Development of Glioblastomas and Its Intervention as a Therapeutic Strategy

Gliomas are solid tumors of the central nervous system (CNS) that originated from different glial cells. The World Health Organization (WHO) classifies these tumors into four groups (I-IV) with increasing malignancy. Glioblastoma (GBM) is the most common and aggressive type of brain tumor classified as grade IV. GBMs are resistant to conventional therapies with poor prognosis after diagnosis even when the Stupp protocol that combines surgery and radiochemotherapy is applied. Nowadays, few novel therapeutic strategies have been used to improve GBM treatment, looking for higher efficiency and lower side effects, but with relatively modest results. The circadian timing system temporally organizes the physiology and behavior of most organisms and daily regulates several cellular processes in organs, tissues, and even in individual cells, including tumor cells. The potentiality of the function of the circadian clock on cancer cells modulation as a new target for novel treatments with a chronobiological basis offers a different challenge that needs to be considered in further detail. The present review will discuss state of the art regarding GBM biology, the role of the circadian clock in tumor progression, and new chrono-chemotherapeutic strategies applied for GBM treatment.

Adjusting the Molecular Clock: The Importance of Circadian Rhythms in the Development of Glioblastomas and Its Intervention as a Therapeutic Strategy

Gliomas are solid tumors of the central nervous system (CNS) that originated from different glial cells. The World Health Organization (WHO) classifies these tumors into four groups (I-IV) with increasing malignancy. Glioblastoma (GBM) is the most common and aggressive type of brain tumor classified as grade IV. GBMs are resistant to conventional therapies with poor prognosis after diagnosis even when the Stupp protocol that combines surgery and radiochemotherapy is applied. Nowadays, few novel therapeutic strategies have been used to improve GBM treatment, looking for higher efficiency and lower side effects, but with relatively modest results. The circadian timing system temporally organizes the physiology and behavior of most organisms and daily regulates several cellular processes in organs, tissues, and even in individual cells, including tumor cells. The potentiality of the function of the circadian clock on cancer cells modulation as a new target for novel treatments with a chronobiological basis offers a different challenge that needs to be considered in further detail. The present review will discuss state of the art regarding GBM biology, the role of the circadian clock in tumor progression, and new chrono-chemotherapeutic strategies applied for GBM treatment.

Tumor-Treating Fields for the treatment of glioblastoma: a systematic review and meta-analysis

BACKGROUND

Tumor-Treating Fields (TTFields) is an emerging treatment modality for glioblastoma (GBM). Studies have shown a good safety profile alongside improved efficacy in newly diagnosed GBM (ndGBM), while a less clear effect was shown for recurrent GBM (rGBM). Despite regulatory support, sectors of the neuro-oncology community have been reluctant to accept it as part of the standard treatment protocol. To establish an objective understanding of TTFields' mechanism of action, safety, efficacy, and economical implications, we conducted a systematic literature review and meta-analysis.

METHODS

A systematic search was conducted in PubMed, Scopus, and Cochrane databases. Twenty studies met the pre-defined inclusion criteria, incorporating 1636 patients (542 ndGBM and 1094 rGBM), and 11 558 patients (6403 ndGBM and 5155 rGBM) analyzed for the clinical outcomes and safety endpoints, respectively.

RESULTS

This study demonstrated improved clinical efficacy and a good safety profile of TTFields. For ndGBM, pooled median overall survival (OS) and progression-free survival (PFS) were 21.7 (95%CI = 19.6-23.8) and 7.2 (95%CI = 6.1-8.2) months, respectively. For rGBM, pooled median OS and PFS were 10.3 (95%CI = 8.3-12.8) and 5.7 (95%CI = 2.8-10) months, respectively. Compliance of ≥75% was associated with an improved OS and the predominant adverse events were dermatologic, with a pooled prevalence of 38.4% (95%CI = 32.3-44.9). Preclinical studies demonstrated TTFields' diverse molecular mechanism of action, its potential synergistic efficacy, and suggest possible benefits for certain populations.

CONCLUSIONS

This study supports the use of TTFields for GBM, alongside the standard-of-care treatment protocol, and provides a practical summary, discussing the current clinical and preclinical aspects of the treatment and their implication on the disease course.

AMOTL2‑knockdown promotes the proliferation, migration and invasion of glioma by regulating β‑catenin nuclear localization

Glioblastoma multiforme (GBM) is the most prevalent type of malignant cancer in the adult central nervous system; however, its mechanism remains unclear. Angiomotin-like 2 (AMOTL2) is a member of the motin family of angiostatin-binding proteins. It has been reported as an oncogene in cervical and breast cancer, but its association with glioma remains unknown. The aim of the present study was to investigate AMOTL2-regulated processes in glioma cell lines using extensive in vitro assays and certain bioinformatics tools. These results revealed that AMOTL2 was downregulated in high-grade glioma cells and tissues, with patients with glioma exhibiting a high AMOTL2 expression having a higher survival rate. The results of the glioma cell phenotype experiment showed that AMOTL2 suppressed GBM proliferation, migration and invasion. In addition, immunoblotting, co-immunoprecipitation and immunofluorescence assays demonstrated that AMOTL2 could directly bind to β-catenin protein, the key molecule of the Wnt signaling pathway, and regulate its downstream genes by regulating β-catenin nuclear translocation. In conclusion, the present study demonstrated that AMOTL2 inhibited glioma proliferation, migration and invasion by regulating β-catenin nuclear localization. Thus, AMOTL2 may serve as a therapeutic target to further improve the prognosis and prolong survival time of patients with glioma.

The Acidic Brain-Glycolytic Switch in the Microenvironment of Malignant Glioma

Malignant glioma represents a fatal disease with a poor prognosis and development of resistance mechanisms against conventional therapeutic approaches. The distinct tumor zones of this heterogeneous neoplasm develop their own microenvironment, in which subpopulations of cancer cells communicate. Adaptation to hypoxia in the center of the expanding tumor mass leads to the glycolytic and angiogenic switch, accompanied by upregulation of different glycolytic enzymes, transporters, and other metabolites. These processes render the tumor microenvironment more acidic, remodel the extracellular matrix, and create energy gradients for the metabolic communication between different cancer cells in distinct tumor zones. Escape mechanisms from hypoxia-induced cell death and energy deprivation are the result. The functional consequences are more aggressive and malignant behavior with enhanced proliferation and survival, migration and invasiveness, and the induction of angiogenesis. In this review, we go from the biochemical principles of aerobic and anaerobic glycolysis over the glycolytic switch, regulated by the key transcription factor hypoxia-inducible factor (HIF)-1α, to other important metabolic players like the monocarboxylate transporters (MCTs)1 and 4. We discuss the metabolic symbiosis model via lactate shuttling in the acidic tumor microenvironment and highlight the functional consequences of the glycolytic switch on glioma malignancy. Furthermore, we illustrate regulation by micro ribonucleic acids (miRNAs) and the connection between isocitrate dehydrogenase (IDH) mutation status and glycolytic metabolism. Finally, we give an outlook about the diagnostic and therapeutic implications of the glycolytic switch and the relation to tumor immunity in malignant glioma.

Mir-139-5p inhibits glioma cell proliferation and progression by targeting GABRA1

Glioma is an extremely aggressive malignant neoplasm of the central nervous system. MicroRNA (miRNA) are known to bind to specific target mRNA to regulate post-transcriptional gene expression and are, therefore, currently regarded as promising biomarkers for glioma diagnosis and prognosis. The aim of the present study was to examine the pathogenesis and potential molecular markers of glioma by comparing the differential expression of miRNA and mRNA between glioma tissue and peritumor brain tissue. We explored the impact of screened core miRNA and mRNA on cell proliferation, invasion, and migration of glioma. An miRNA expression profile dataset (GSE90603) and a transcriptome profile dataset (GSE90598) were downloaded from combined miRNA-mRNA microarray chips in the Gene Expression Omnibus (GEO) database. Overall, 59 differentially expressed miRNAs (DEMs) and 419 differentially expressed genes (DEGs) were identified using the R limma software package. FunRich software was used to predict DEM target genes and miRNA-gene pairs, and Perl software was used to find overlapping genes between DEGs and DEM target genes. There were 129 overlapping genes regulated by nine miRNAs between target genes of the DEMs and DEGs. The Chinese Glioma Genome Atlas(CGGA) was analyzed in order to identify miRNAs with diagnostic and prognostic significance. MiR-139-5p, miR-137, and miR-338-3p were validated to be significantly linked to prognosis in glioma patients. Finally, we validated that miR-139-5p affected glioma malignant biological behavior via targeting gamma-aminobutyric acid A receptor alpha 1(GABRA1) through rescue experiments. Low miR-139-5p expression was correlated with survival probability and World Health Organization (WHO) grade. MiR-139-5p overexpression inhibited cell proliferation, migration, and invasion of glioma in vitro. GABRA1 was identified as a functional downstream target of miR-139-5p. Decreased GABRA1 expression was related to similar biological roles as miR-139-5p overexpression while upregulation of GABRA1 effectively reversed the inhibition effects of miR-139-5p. These results demonstrate a novel axis for miR-139-5p/GABRA1 in glioma progression and provide potential prognostic predictors and therapeutic target for glioma patients.

MCT4 Promotes Tumor Malignancy in F98 Glioma Cells

Monocarboxylate transporter 4 (MCT4, SLC16A3) is elevated under hypoxic conditions in many malignant tumors including gliomas. Moreover, MCT4 expression is associated with shorter overall survival. However, the functional consequences of MCT4 expression on the distinct hallmarks of cancer have not yet been explored at the cellular level. Here, we investigated the impact of MCT4 overexpression on proliferation, survival, cell death, migration, invasion, and angiogenesis in F98 glioma cells. Stable F98 glioma cell lines with MCT4 overexpression, normal expression, and knockdown were generated. Distinct hallmarks of cancer were examined using in silico analysis, various in vitro cell culture assays, and ex vivo organotypic rat brain slice culture model. Consistent with its function as lactate and proton exporter, MCT4 expression levels correlated inversely with extracellular pH and proportionally with extracellular lactate concentrations. Our results further indicate that MCT4 promotes proliferation and survival by altered cell cycle regulation and cell death mechanisms. Moreover, MCT4 overexpression enhances cell migration and invasiveness via reorganization of the actin cytoskeleton. Finally, MCT4 inhibition mitigates the induction of angiogenesis, suggesting that MCT4 also plays a crucial role in tumor-related angiogenesis. In summary, our data highlight MCT4/SLC16A3 as a key gene for distinct hallmarks of tumor malignancy in glioma cells.

Frontiers in the treatment of glioblastoma: Past, present and emerging

Glioblastoma (GBM) is one of the most aggressive cancers of the brain. Despite extensive research over the last several decades, the survival rates for GBM have not improved and prognosis remains poor. To date, only a few therapies are approved for the treatment of GBM with the main reasons being: 1) significant tumour heterogeneity which promotes the selection of resistant subpopulations 2) GBM induced immunosuppression and 3) fortified location of the tumour in the brain which hinders the delivery of therapeutics. Existing therapies for GBM such as radiotherapy, surgery and chemotherapy have been unable to reach the clinical efficacy necessary to prolong patient survival more than a few months. This comprehensive review evaluates the current and emerging therapies including those in clinical trials that may potentially improve both targeted delivery of therapeutics directly to the tumour site and the development of agents that may specifically target GBM. Particular focus has also been given to emerging delivery technologies such as focused ultrasound, cellular delivery systems nanomedicines and immunotherapy. Finally, we discuss the importance of developing novel materials for improved delivery efficacy of nanoparticles and therapeutics to reduce the suffering of GBM patients.

Assessment of the effect of therapy in a rat model of glioblastoma using [18F]FDG and [18F]FCho PET compared to contrast-enhanced MRI

Objective

We investigated the potential of [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG) and [¹⁸F]Fluoromethylcholine ([¹⁸F]FCho) PET, compared to contrast-enhanced MRI, for the early detection of treatment response in F98 glioblastoma (GB) rats.

Methods

When GB was confirmed on T2- and contrast-enhanced T1-weighted MRI, animals were randomized into a treatment group (n = 5) receiving MRI-guided 3D conformal arc micro-irradiation (20 Gy) with concomitant temozolomide, and a sham group (n = 5). Effect of treatment was evaluated by MRI and [¹⁸F]FDG PET on day 2, 5, 9 and 12 post-treatment and [¹⁸F]FCho PET on day 1, 6, 8 and 13 post-treatment. The metabolic tumor volume (MTV) was calculated using a semi-automatic thresholding method and the average tracer uptake within the MTV was converted to a standard uptake value (SUV).

Results

To detect treatment response, we found that for [¹⁸F]FDG PET (SUV_mean x MTV) is superior to MTV only. Using (SUV_mean x MTV), [¹⁸F]FDG PET detects treatment effect starting as soon as day 5 post-therapy, comparable to contrast-enhanced MRI. Importantly, [¹⁸F]FDG PET at delayed time intervals (240 min p.i.) was able to detect the treatment effect earlier, starting at day 2 post-irradiation. No significant differences were found at any time point for both the MTV and (SUV_mean x MTV) of [¹⁸F]FCho PET.

Conclusions

Both MRI and particularly delayed [¹⁸F]FDG PET were able to detect early treatment responses in GB rats, whereas, in this study this was not possible using [¹⁸F]FCho PET. Further comparative studies should corroborate these results and should also include (different) amino acid PET tracers.

Involvement of N-methylpurine DNA glycosylase in resistance to temozolomide in patient-derived glioma cells

Chemotherapy for high-grade astrocytic tumors is mainly based on the use of temozolomide (TMZ), whose efficacy is limited by resistance mechanisms. Despite many investigations pointing to O6-methylguanine-DNA-methyltransferase (MGMT) as being responsible for tumor chemo-resistance, its expression does not predict an accurate response in most gliomas, suggesting that MGMT is not the only determinant of response to treatment. In this sense, several reports indicate that N-methylpurine-DNA-glycosylase (MPG) may be involved in that resistance. With that in mind, we evaluated for the first time the degree of resistance to TMZ treatment in 18 patient-derived glioma cells and its association with MGMT and MPG mRNA levels. Viability cell assays showed that TMZ treatment hardly caused growth inhibition in the patient-derived cells, even in high concentrations, indicating that all primary cultures were chemo-resistant. mRNA expression analyses showed that the TMZ-resistant phenotype displayed by cells is associated with an elevated expression of MPG to a greater extent than it is with transcript levels of MGMT. Our findings suggest that not only is MGMT implicated in resistance to TMZ but MPG, the first enzyme in base excision repair processing, is also involved, supporting its potential role as a target in anti-resistance chemotherapy for astrocytoma and glioblastoma.

Anti-neoplastic Potential of Flavonoids and Polysaccharide Phytochemicals in Glioblastoma

Clinically, gliomas are classified into four grades, with grade IV glioblastoma multiforme being the most malignant and deadly, which accounts for 50% of all gliomas. Characteristically, glioblastoma involves the aggressive proliferation of cells and invasion of normal brain tissue, outcomes as poor patient prognosis. With the current standard therapy of glioblastoma; surgical resection and radiotherapy followed by adjuvant chemotherapy with temozolomide, it remains fatal, because of the development of drug resistance, tumor recurrence, and metastasis. Therefore, the need for the effective therapeutic option for glioblastoma remains elusive. Previous studies have demonstrated the chemopreventive role of naturally occurring pharmacological agents through preventing or reversing the initiation phase of carcinogenesis or arresting the cancer progression phase. In this review, we discuss the role of natural phytochemicals in the amelioration of glioblastoma, with the aim to improve therapeutic outcomes, and minimize the adverse side effects to improve patient's prognosis and enhancing their quality of life.

Cytotoxic and Senolytic Effects of Methadone in Combination with Temozolomide in Glioblastoma Cells

Methadone is an analgesic drug used for pain treatment and heroin substitution. Recently, methadone has been proposed to be useful also for cancer therapy, including glioblastoma multiforme (GBM), the most severe form of brain cancer, because experiments on cultured glioma cells treated with doxorubicin showed promising results. Doxorubicin, however, is not used first-line in GBM therapy. Therefore, we analyzed the cytotoxic effect of methadone alone and in combination with temozolomide, a DNA-alkylating drug that is first-line used in GBM treatment, utilizing GBM-derived cell lines and a human fibroblast cell line. We show that methadone is cytotoxic on its own, inducing apoptosis and necrosis, which was observed at a concentration above 20 µg/mL. Methadone was similar toxic in isogenic MGMT expressing and non-expressing cells, and in LN229 glioblastoma and VH10T human fibroblasts. The apoptosis-inducing activity of methadone is not bound on the opioid receptor (OR), since naloxone, a competitive inhibitor of OR, did not attenuate methadone-induced apoptosis/necrosis. Administrating methadone and temozolomide together, temozolomide had no impact on methadone-induced apoptosis (which occurred 3 days after treatment), while temozolomide-induced apoptosis (which occurred 5 days after treatment) was unaffected at low (non-toxic) methadone concentration (5 µg/mL), and at high (toxic) methadone concentration (20 µg/mL) the cytotoxic effects of methadone and temozolomide were additive. Methadone is not genotoxic, as revealed by comet and γH2AX assay, and did not ameliorate the genotoxic effect of temozolomide. Further, methadone did not induce cellular senescence and had no effect on temozolomide-induced senescence. Although methadone was toxic on senescent cells, it cannot be considered a senolytic drug since cytotoxicity was not specific for senescent cells. Finally, we show that methadone had no impact on the MGMT promoter methylation. Overall, the data show that methadone on glioblastoma cells in vitro is cytotoxic and induces apoptosis/necrosis at doses that are above the level that can be achieved in vivo. It is not genotoxic, and does not ameliorate the cell killing or the senescence-inducing effect of temozolomide (no synergistic effect), indicating it has no impact on temozolomide-induced signaling pathways. The data do not support the notion that concomitant methadone treatment supports temozolomide-based chemotherapy.

Predicting Individual Prognosis and Grade of Patients with Glioma Based on Preoperative Eosinophil and Neutrophil-to-Lymphocyte Ratio

Purpose

Eosinophils are proven to play a role in the prognosis of some malignant-tumors. The prognostic value of eosinophils in glioma patients is, however, scarcely reported. The authors of this article have designed a novel prognostic indicator based on eosinophils and the neutrophil-to-lymphocyte ratio (NLR), named ENS, to predict the survival of patients with glioma.

Methods

A retrospective study was conducted on 217 glioma patients. The cut-off values for eosinophil, NLR, and other clinical variables were determined by the receiver operating characteristic (ROC) curve analysis. Patients with both low eosinophil count (<0.08 ×10⁹/L) and high NLR (≥1.70) were given a score of 2. Those with one or neither got a score of 1 or 0, respectively. The nomogram was based on ENS and several other clinical variables, its performance was determined by the concordance index (c-index).

Results

Our results showed that ENS is an independent prognostic indicator for overall survival (OS). The three-year OS rates for low-grade glioma patients (LGGs) were 84.0%, 69.0%, and 46.4% for ENS=0, ENS=1, and ENS=2, respectively (P=0.014). The three-year OS incidence for LGGs stratified into eosinophils count ≥0.08×109/L and<0.08×109/L subgroups were 88.1% and 80.0%, respectively (P=0.043). ENS was positively correlated with glioma grade (r=0.311, P<0.001). The c-index for OS prognosis was 0.80 using this nomogram in LGGs.

Conclusion

Preoperative ENS can predict OS to some extent for LGGs and can increase prognostic accuracy for individual OS in LGGs postoperatively when incorporating other clinical variables compose a nomogram.

Dequalinium chloride inhibits the growth of human glioma cells in vitro and vivo: a study on molecular mechanism and potential targeted agents

BACKGROUND

Our current understanding of the role of dequalinium chloride (DECA) in the progression of glioma remains very limited. This study was aimed to investigate the effect of DECA on human glioma cell lines in vitro and vivo.

METHODS

The underlying molecular mechanism was analyzed for developing potential targeted agents. MTT assay, genomic DNA electrophoresis, DAPI staining, TUNEL staining, and wound scratch assay were performed to evaluate the effect of DECA on human glioma cell lines. Bioinformatics methods were used to screen the possible signaling pathway proteins, and the expression of these proteins and the corresponding mRNA was measured.

RESULTS

DECA significantly inhibited the growth and proliferation of human glioma cells. Screening of apoptosis-related proteins showed the mRNA expression level of 6 genes was significantly changed after DECA administration.

CONCLUSION

This study shows that DECA effectively inhibits the growth of glioma cells in vitro and vivo. DECA may promote glioma cell apoptosis by affecting the expression of NFKB2, HRAS, NF1, CBL, RAF1, and BCL-2 genes.

ST1926 inhibits glioma progression through regulating mitochondrial complex II

The antitumor activity of atypical adamantyl retinoid ST1926 has been frequently reported in cancer studies; nevertheless, its effect on glioma has not been fully understood. Mitochondria are critical in regulating tumorigenesis and are defined as a promising target for anti-tumor therapy. In the present study, we found that ST1926 might be a mitochondria-targeting anti-glioma drug. ST1926 showed significantly inhibitory role in the viability of glioma cells mainly through inducing apoptosis and autophagy. The results showed that ST1926 alleviated mitochondria-regulated bioenergetics in glioma cells via reducing ATP production and promoting reactive oxygen species production. Importantly, ST1926 significantly impaired complex II (CII) function, which was associated with the inhibition of succinate dehydrogenase (SDH) activity. In addition, the effects of ST1926 on the induction of apoptosis and ROS were further promoted by the treatment of CII inhibitors, including TTFA and 3-NPA. Furthermore, the in vivo experiments confirmed the role of ST1926 in suppressing xenograft tumor growth with few toxicity. Therefore, ST1926 might be an effective anti-glioma drug through targeting CII.

4-Methylumbelliferone as a potent and selective antitumor drug on a glioblastoma model

Glioblastoma (GBM), the most frequent primary tumor of the central nervous system, has a median survival of 14.6 months. 4-Methylumbelliferone (4MU) is a coumarin derivative widely used as a hyaluronan synthesis inhibitor with proven antitumor activity and without toxic effects reported. We aim to evaluate the antitumor effect of 4MU alone or combined with temozolomide (TMZ) on a GBM cell line, its absence of toxicity on brain cells and its selectivity for tumor cells. The antitumor effect of 4MU alone or combined with TMZ was evaluated on GL26 cells by assessing the metabolic activity through the XTT assay, cell proliferation by BrdU incorporation assay, migration by the wound healing assay, cell death by fluorescein diacetate/propidium iodide (FDA/PI) staining, apoptosis by membrane asymmetry and DNA fragmentation and metalloproteinase activity by zymography. The levels of hyaluronan and its capacity to counteract the effects of 4MU and the expression of RHAMM and CD44 were also determined. The toxicity and selectivity of 4MU were determined by XTT assay and PI staining on normal brain primary cell culture (NBPC-GFP) and GL26/NBPC-GFP cocultures. The GL26 cells expressed RHAMM but not CD44 while synthetized hyaluronan. 4MU decreased hyaluronan synthesis, diminished proliferation and induced apoptosis while reducing cell migration and the activity of metalloproteinases, which was restored by addition of hyaluronic acid. Furthermore, 4MU sensitized GL26 cells to the TMZ effect and showed selective toxicity on tumor cells without exhibiting neurotoxic effects. We demonstrated for the first time the cytotoxic effect of 4MU on GBM cells, highlighting its potential usefulness to improve GBM treatment.

A Novel Scoring System Based on Peripheral Blood Test in Predicting Grade and Prognosis of Patients with Glioma

Purpose

To explore the value of F-NLR-AGR score based on preoperative fibrinogen, neutrophil to lymphocyte ratio (NLR), and albumin to globulin ratio (AGR) in predicting the prognosis in patients with glioma.

Patients and methods

203 glioma patients were retrospectively analyzed. Receiver-operating characteristic (ROC) curve analysis was used to determine the optimal cut-off values for NLR, AGR, and fibrinogen. According to these cut-off values, patients with high NLR (>1.90), low AGR (<1.54), and elevated fibrinogen (>2.61 g/L) were defined as a score of 3, if none of the patients' three parameters met these standards they were given a score of 0, if any two or one parameter met these standards they were scored as 2 or 1, respectively. The correlation between F-NLR-AGR score and glioma grade was also evaluated.

Results

The three-year overall survival (OS) rate and the mean overall survival in patients with F-NLR-AGR=3 were lower than those of patients with F-NLR-AGR = 2, 1 or 0 [17.6% vs 35.2%, 66.9% or 83.7% (26.0 vs 39.0, 64.0 or 81.0 months), P<0.001]. Multivariate analysis revealed that age (HR=2.071; 95% CI=1.195-3.588; P=0.009), WHO grade (P<0.001), and F-NLR-AGR score (P<0.001) were independent prognostic factors for OS. Spearman's rank correlation analysis revealed that F-NLR-AGR score was positively correlated with glioma grade (r=0.278, P<0.01).

Conclusion

Preoperative F-NLR-AGR score was correlated with glioma grading, high F-NLR-AGR score was an independent predictor of poor prognosis in glioma. Therefore, the scoring system may be applied in clinical practice to identify high-risk patients.

Intensity-modulated radiotherapy, coplanar volumetric-modulated arc, therapy, and noncoplanar volumetric-modulated arc therapy in, glioblastoma: A dosimetric comparison

OBJECTIVE

Advanced techniques such as volumetric-modulated arc therapy (VMAT) may reduce radiation damage and improve the quality of life for patients.We performed a study comparing dose distributions to the planning target volumes(PTVs) and other organs at risk (OARs) of intensity-modulated radiotherapy (IMRT),coplanar VMAT (coVMAT), and non-coplanar VMAT (ncVMAT).

PATIENTS AND METHODS

13 patients with GBM who had undergone postoperative radiotherapy were enrolled. Three plans for each patient were created, namely, IMRT, coVMAT, and ncVMAT. Prescription doses and normal-tissue constraints were identical for these three plans. The dosimetric differences of target dose distribution, conformity index (CI), homogeneity index (HI), the gradient index (GI), dose of OARs, monitor units (MUs) and beam-on times among these three plans were investigated.

RESULTS

These three techniques resulted in comparable maximum, minimum, and mean PTV doses. Small but insignificant differences were observed in GI,CI, and HI. Compared with IMRT, VMAT plans showed statistically significant reductions in the mean doses to the optic chiasm (P < 0.05). Compared with IMRT, VMAT techniques significantly reduced the number of MUs and less beam-on time than IMRT techniques (P ＜ 0.05). However, calculation times were significantly longer for ncVMAT and coVMAT plans at 12 and 12.3 min, versus 2.6 min for IMRT. Our study showed that IMRT or VMAT planning is feasible and efficient for patients with GBM.Compared to IMRT plans, ncVMAT or coVMAT plans showed similar PTV coverage and comparable OARs sparing. VMAT plans significantly reduces the mean doses to the optic chiasm than IMRT plans.

CONCLUSION

There was no obvious superiority of ncVMAT over coVMAT in target coverage and sparing of OARs.Compared with IMRT, VMAT techniques significantly reduced the number of MUs and beam-on time but extended the calculation times.

Tibolone Effects on Human Glioblastoma Cell Lines

BACKGROUND

Ovarian steroid hormones are involved in modulating the growth of glioblastomas (the most common, aggressive, and lethal brain tumor) through the interaction with their intracellular receptors. Activation of sex hormone receptors is involved in glioblastomas progression. Tibolone (TIB) is a selective tissue estrogenic activity regulator widely prescribed to treat menopausal symptoms and to prevent bone lost. The effects of TIB on the growth of glioblastoma are unknown.

AIM OF THE STUDY

To evaluate the effects of TIB on cell number, migration, and invasion of two derived human glioblastoma cell lines (U251 MG and U87), as well as the role of this steroid in estrogen and progesterone receptors activity and content.

METHODS

U251-MG and U87 human glioblastoma cell lines were grown with different doses of TIB. The number of cells was determined and migration and invasion tests were carried out. Protein expression was performed by Western blot.

RESULTS

We observed that TIB (10 nM) increased the number of cells by inducing proliferation with no effects on cell migration or invasion. The increase in cell proliferation induced by TIB was blocked by estrogen (ERs) or progesterone receptor (PRs) antagonists, ICI 182, 780 and RU 486, suggesting that these receptors mediate proliferating actions of TIB; TIB also modified the content of ERs and PRs by increasing ER-α, ER-β, and PR-B, while decreased PR-A.

CONCLUSION

Our results suggest that TIB increases cell number and proliferation of human glioblastoma cells through the regulation of ERs and PRs actions and content.

Technical feasibility of [18F]FET and [18F]FAZA PET guided radiotherapy in a F98 glioblastoma rat model

Background

Glioblastoma (GB) is the most common primary malignant brain tumor. Standard medical treatment consists of a maximal safe surgical resection, subsequently radiation therapy (RT) and chemotherapy with temozolomide (TMZ). An accurate definition of the tumor volume is of utmost importance for guiding RT. In this project we investigated the feasibility and treatment response of subvolume boosting to a PET-defined tumor part.

Method

F98 GB cells inoculated in the rat brain were imaged using T2- and contrast-enhanced T1-weighted (T1w) MRI. A dose of 20 Gy (5 × 5 mm²) was delivered to the target volume delineated based on T1w MRI for three treatment groups. Two of those treatment groups received an additional radiation boost of 5 Gy (1 × 1 mm²) delivered to the region either with maximum [¹⁸F]FET or [¹⁸F]FAZA PET tracer uptake, respectively. All therapy groups received intraperitoneal (IP) injections of TMZ. Finally, a control group received no RT and only control IP injections. The average, minimum and maximum dose, as well as the D₉₀-, D₅₀- and D₂- values were calculated for nine rats using both RT plans. To evaluate response to therapy, follow-up tumor volumes were delineated based on T1w MRI.

Results

When comparing the dose volume histograms, a significant difference was found exclusively between the D₂-values. A significant difference in tumor growth was only found between active therapy and sham therapy respectively, while no significant differences were found when comparing the three treatment groups.

Conclusion

In this study we showed the feasibility of PET guided subvolume boosting of F98 glioblastoma in rats. No evidence was found for a beneficial effect regarding tumor response. However, improvements for dose targeting in rodents and studies investigating new targeted drugs for GB treatment are mandatory.

Electronic supplementary material

The online version of this article (10.1186/s13014-019-1290-4) contains supplementary material, which is available to authorized users.

Polycomb complex mediated epigenetic reprogramming alters TGF-β signaling via a novel EZH2/miR-490/TGIF2 axis thereby inducing migration and EMT potential in glioblastomas

Recent advancement in understanding cancer etiology has highlighted epigenetic deregulation as an important phenomenon leading to poor prognosis in glioblastoma (GBM). Polycomb repressive complex 2 (PRC2) is one such important epigenetic modifier reportedly altered in GBM. However, its defined mechanism in tumorigenesis still remains elusive. In present study, we analyzed our in-house ChIPseq data for H3k27me3 modified miRNAs and identified miR-490-3p to be the most common target in GBM with significantly downregulated expression in glioma patients in both TCGA and GBM patient cohort. Our functional analysis delineates for the first time, a central role of PRC2 catalytic unit EZH2 in directly regulating expression of this miRNA and its host gene CHRM2 in GBM. In accordance, cell line treatment with EZH2 siRNA and 5-azacytidine also confirmed its coregulation by CpG and histone methylation based epigenetic mechanisms. Furthermore, induced overexpression of miR-490-3p in GBM cell lines significantly inhibited key hallmarks including cellular proliferation, colony formation and spheroid formation, as well as epithelial-to-mesenchymal transition (EMT), with downregulation of multiple EMT transcription factors and promigratory genes (MMP9, CCL5, PIK3R1, ICAM1, ADAM17 and NOTCH1). We also for the first time report TGFBR1 and TGIF2 as two direct downstream effector targets of miR-490-3p that are also deregulated in GBM. TGIF2, a novel target, was shown to promote migration and EMT that could partially be rescued by miR-490-3p overexpression. Overall, this stands as a first study that provides a direct link between epigenetic modulator EZH2 and oncogenic TGF-β signaling involving novel miR-490-3p/TGIF2/TGFBR1 axis, that being targetable might be promising in developing new therapeutic intervention strategies for GBM.

Prognostic Value of MTV, SUVmax and the T/N Ratio of PET/CT in Patients with Glioma: A Systematic Review and Meta-Analysis

Background: In the past decade, positron emission tomography/computed tomography (PET/CT) has become an important imaging tool for clinical assessment of tumor patients. Our meta-analysis aimed to compare the predictive value of PET/CT parameters regard to overall survival (OS) and progression-free survival (PFS) outcomes in glioma.

Methods: Relevant articles were systematically searched in PMC, PubMed, EMBASE and WEB of science. Studies involving the prognostic roles of PET/CT parameters with OS and PFS in glioma patients were evaluated. The impact of metabolic tumor volume (MTV), maximal standard uptake value (SUVmax), and the ratio of uptake in tumor to normal (T/N ratio) on survival was measured by calculating combined hazard ratios (HRs) and 95% confidence intervals (CIs).

Results: A total of 32 articles with 1715 patients were included. The combined HRs of higher MTV, higher SUVmax and higher T/N ratio for OS were 1.14 (95% CI: 0.98-1.32, P heterogeneity<0.001), 1.69 (95% CI: 1.18-2.41, P heterogeneity<0.001) and 1.68 (95% CI: 1.40-2.01, P heterogeneity< 0.001), respectively. Regarding PFS, the combined HRs were 1.04 (95% CI: 0.97-1.11, P heterogeneity=0.002) with higher MTV, 1.45 (95% CI: 1.11-1.90, P heterogeneity<0.001) with higher SUVmax and 2.07 (95% CI: 1.45-2.95, P heterogeneity<0.001) with higher T/N ratio. Results remained similar in the sub-group analyses.

Conclusion: PET/CT parameters T/N ratio may be a significant prognostic factor in patients with glioma. Evidence of SUVmax and MTV needed more large-scale studies performed to validate. PET/CT scan could be a promising technique to provide prognostic information for these patients.

Loquat-Inspired Janus Drug Delivery System for Flexible and Robust Tumor Targeting Therapy

With the inspiration of the shape of the loquat fruit, here, we developed a similarly shaped Janus carrier. This peculiar gold rod-partially exposed structure not only significantly increased the drug loading capability but also improved its infrared response efficiency. A better effect of drug-photothermal treatment thus could be realized. With the aid of an external 3D printed drug guiding device, this carrier could accurately reach different affected areas. The subsequent infrared triggered multiple tumor therapy, thus, could be conducted in the designated location. The corresponding experimental results demonstrated the reliability, flexibility, and biocompatibility of the proposed drug delivery system for two different tumor targeting treatments.

DNA aptamers from whole-cell SELEX as new diagnostic agents against glioblastoma multiforme cells

Glioma is a cancer derived from transformed glial cells, which are often invasive and display a heterogeneous cell population. Currently, no trustworthy biomarkers for the detection and risk stratification of glioma have been discovered. The objective of the present research was to select DNA aptamers to facilitate early diagnosis and effective therapy of glioma. Using cell-SELEX, three aptamers (WYZ-37, WYZ-41, WYZ-50), which can specifically recognize the molecular differences between target cells T98G and negative cells SVGp12, were identified. The best binding sequences WYZ-41 and WYZ-50 were optimized in length, resulting in aptamer sequences WYZ-41a and WYZ-50a. The Kd values of the aptamers WYZ-41a and WYZ-50a against the target cell line were found to be 1.0 ± 0.2 nM and 2.8 ± 0.6 nM, respectively, which are better than the Kds for full-length aptamers WYZ-41 and WYZ-50. Flow cytometry analysis results show that the aptamers WYZ-41a and WYZ-50a do not influence each other in mutual binding, and that they effectively detect the target even in complex mixtures, such as undiluted fetal bovine serum (FBS) and cerebral spinal fluid (CSF), indicating that aptamers WYZ-41a and WYZ-50a have excellent potential as aptamer pairs to improve the accuracy of glioma diagnosis.

Doxorubicin and indocyanine green loaded superparamagnetic iron oxide nanoparticles with PEGylated phospholipid coating for magnetic resonance with fluorescence imaging and chemotherapy of glioma

Background

Glioma represents the most common malignant brain tumor. Outcomes of surgical resection are often unsatisfactory due to low sensitivity or resolution of imaging methods. Moreover, the use of traditional chemotherapeutics, such as doxorubicin (DOX), is limited due to their low blood-brain barrier (BBB) permeability. Recently, the development of nanotechnology could overcome these obstacles.

Materials and methods

Hydrophobic superparamagnetic iron oxide nanoparticles (SPIO NPs) were prepared with the use of thermal decomposition method. They were coated with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-PEG 2000) and DOX using a thin-film hydration method followed by loading of indocyanine green (ICG) into the phospholipid layers. Details regarding the characteristics of NPs were determined. The in vitro biocompatibility and antitumor efficacy were established with the use of MTT assay. In vivo fluorescence and magnetic resonance (MR) imaging were used to evaluate BBB penetration and accumulation of NPs at the tumor site. Antitumor efficacy was evaluated using measures of tumor size, median survival times, body weights, and H&E staining.

Results

The multifunctional NPs generated had an average diameter of 22.9 nm, a zeta potential of -38.19 mV, and were capable of providing a sustained release of DOX. In vitro experiments demonstrated that the SPIO@DSPE-PEG/DOX/ICG NPs effectively enhanced cellular uptake of DOX as compared with that of free DOX. In vivo fluorescence and MR imaging revealed that the NPs not only effectively crossed the BBB but selectively accumulated at the tumor site. Meanwhile, among all groups studied, C6 glioma-bearing rats treated with the NPs exhibited the maximal degree of therapeutic efficacy, including smallest tumor volume, lowest body weight loss, and longest survival times, with no obvious side effects.

Conclusion

These results suggest that the SPIO@DSPE-PEG/DOX/ICG NPs can not only function as a nanoprobe for MR and fluorescence bimodal imaging, but also as a vehicle to deliver chemotherapeutic drugs to the tumor site, to achieve the theranostic treatment of glioma.

Magnetic resonance imaging-guided radiation therapy using animal models of glioblastoma

Glioblastoma is the most aggressive and most common malignant primary brain tumour in adults and has a high mortality and morbidity. Because local tumour control in glioblastoma patients is still elusive in the majority of patients, there is an urgent need for alternative treatment strategies. However, to implement changes to the existing clinical standard of care, research must be conducted to develop alternative treatment strategies. A novel approach in radiotherapy is the introduction of pre-clinical precision image-guided radiation research platforms. The aim of this review is to give a brief overview of the efforts that have been made in the field of radiation research using animal models of glioblastoma. Because MRI has become the reference imaging technique for treatment planning and assessment of therapeutic responses in glioblastoma patients, we will focus in this review on small animal radiotherapy combined with MRI.

Lauryl Gallate Induces Apoptotic Cell Death through Caspase-dependent Pathway in U87 Human Glioblastoma Cells In Vitro

BACKGROUND/AIM

The treatment of human glioma tumor is still an unmet medical need. Natural products are always promising resources for discovery of anticancer drugs. Lauryl gallate (LG) is one of the derivatives of gallic acid, widely present in plants, that has been shown to induce anticancer activities in many human cancer cell lines; however, it has not been studied in human glioma cell lines. Thus, the effects of LG on human glioblastoma U87 cells were investigated in the present in vitro study.

MATERIALS AND METHODS

Cell morphology and viability were examined by phase-contrast microscopy. Annexin V/Propidium iodide (PI) double staining were performed and assayed by flow cytometry to confirm that viable cell number reduction was due to the induction of apoptosis. Furthermore, U87 cells were exposed to LG in various concentrations and were analyzed by caspase activity assay. To further confirm that LG induced apoptotic cell death, the expression of apoptosis-associated proteins in LG-treated U87 cells was tested by western blot.

RESULTS

LG induced morphological changes and decreased viability in U87 cells. Annexin V/PI double staining revealed that LG induced apoptotic cell death in U87 cells in a dose-dependent manner. The increased activities of caspase-2, -3, -8 and -9 demonstrated that LG induced U87 cell apoptosis through a caspase-dependent pathway. In terms of molecular level, LG increased pro-apoptotic proteins Bax and Bak and decreased anti-apoptotic protein Bcl-2 in U87 cells. Furthermore, LG also suppressed the expression of p-Akt, Pak1, Hif-1α and Hif-2α, β-catenin and Tcf-1 in U87 cells.

CONCLUSION

These results suggest that LG induced apoptotic cell death via the caspase-dependent pathway in U87 cells.

FoxG1 facilitates proliferation and inhibits differentiation by downregulating FoxO/Smad signaling in glioblastoma

BACKGROUND

To investigate the effects and underlying molecular mechanisms of FoxG1 expression on glioblastoma multiforme (GBM) models.

METHODS

Expression levels of FoxG1 and other cancer-related biomarkers were evaluated by qRT-PCR, immunoblotting and immunohistochemistry. Crystal violet staining and MTT assay and were applied in this study to verify cell proliferation ability and viability of GBM cell models with/without drug treatment.

RESULTS

Immunohistochemical and qRT-PCR assays showed that endogenous FoxG1 expression levels were positively correlated to the GBM disease progression. Overexpression of FoxG1 protein resulted in increased cell viability, G2/M cell cycle arrest, as well as the downregulation of p21 and cyclin B1. In addition, western blot assays reported that enforced expression of FoxG1 suppressed GAPF and facilitated the expression of Sox2 and Sox5. Meanwhile the downstream targets of FoxG1, such as FoxO1 and pSmad1/5/8 were activated. Overexpression of FoxG1 under TMZ treatment restored the cell viability as well as the expression levels of Sox2 and Sox5, yet downregulated expression levels of p21 and cyclin B1. The downstream FoxG1-induced FoxO/Smad signaling was re-inhibited under TMZ treatments.

CONCLUSIONS

Our findings suggest that FoxG1 functions as an onco-factor by promoting proliferation, as well as inhibiting differential responses in glioblastoma by downregulating FoxO/Smad signaling.

Efficacy of D,L-methadone in the treatment of glioblastoma in vitro

AIM

Recently, D,L-methadone has been put forward as adjuvant treatment in glioblastoma (GBM).

METHODS

We analyzed the μ-opioid receptor expression in a set of GBM cell lines and investigated the efficacy of D,L-methadone alone and in combination with temozolomide (TMZ). Results & conclusion: Expression of the μ-opioid receptor was similar in the tested cell lines. High concentrations of D,L-methadone induced apoptosis in all cell lines and showed treatment interaction with TMZ. However, in lower dosages, reflecting clinically attainable concentrations, D,L-methadone alone showed no efficacy, and induced even higher proliferation in one specific cell line. Also, no interaction with TMZ was observed. These results suggest caution to the premature use of D,L-methadone in the treatment of GBM patients.

VDAC1 is a molecular target in glioblastoma, with its depletion leading to reprogrammed metabolism and reversed oncogenic properties

Background

Glioblastoma (GBM), an aggressive brain tumor with frequent relapses and a high mortality, still awaits an effective treatment. Like many cancers, GBM cells acquire oncogenic properties, including metabolic reprogramming, vital for growth. As such, tumor metabolism is an emerging avenue for cancer therapy. One relevant target is the voltage-dependent anion channel 1 (VDAC1), a mitochondrial protein controlling cell energy and metabolic homeostasis.

Methods

We used VDAC1-specific short interfering (si)RNA (si-VDAC1) to treat GBM cell lines and subcutaneous or intracranial-orthotopic GBM xenograft mouse models. Tumors were monitored using MRI, immunohistochemistry, immunoblotting, immunofluorescence, quantitative real-time PCR, transcription factor expression, and DNA microarray analyses.

Results

Silencing VDAC1 expression using si-VDAC1 in 9 glioblastoma-related cell lines, including patient-derived cells, led to marked decreases in VDAC1 levels and cell growth. Using si-VDAC1 in subcutaneous or intracranial-orthotopic GBM models inhibited tumor growth and reversed oncogenic properties, such as reprogrammed metabolism, stemness, angiogenesis, epithelial-mesenchymal transition, and invasiveness. In cells in culture, si-VDAC1 inhibits cancer neurosphere formation and, in tumors, targeted cancer stem cells, leading to their differentiation into neuronal-like cells. These VDAC1 depletion-mediated effects involved alterations in transcription factors regulating signaling pathways associated with cancer hallmarks.

Conclusion

VDAC1 offers a target for GBM treatment, allowing for attacks on the interplay between metabolism and oncogenic signaling networks, leading to tumor cell differentiation into neuron- and astrocyte-like cells. Simultaneously attacking all of these processes, VDAC1 depletion overcame GBM heterogeneity and can replace several anticancer drugs that separately target angiogenesis, proliferation, or metabolism.

Mitochondrial VDAC1-based peptides: Attacking oncogenic properties in glioblastoma

Glioblastoma multiforme (GBM), a primary brain malignancy characterized by high morbidity, invasiveness, proliferation, relapse and mortality, is resistant to chemo- and radiotherapies and lacks effective treatment. GBM tumors undergo metabolic reprograming and develop anti-apoptotic defenses. We targeted GBM with a peptide derived from the mitochondrial protein voltage-dependent anion channel 1 (VDAC1), a key component of cell energy, metabolism and apoptosis regulation. VDAC1-based cell-penetrating peptides perturbed cell energy and metabolic homeostasis and induced apoptosis in several GBM and GBM-derived stem cell lines. We found that the peptides simultaneously attacked several oncogenic properties of human U-87MG cells introduced into sub-cutaneous xenograft mouse model, inhibiting tumor growth, invasion, and cellular metabolism, stemness and inducing apoptosis. Peptide-treated tumors showed decreased expression of all tested metabolism-related enzymes and transporters, and elevated levels of apoptotic proteins, such as p53, cytochrome c and caspases. Retro-Tf-D-LP4, containing the human transferrin receptor (TfR)-recognition sequence, crossed the blood-brain barrier (BBB) via the TfR that is highly expressed in the BBB to strongly inhibit tumor growth in an intracranial xenograft mouse model. In summary, the VDAC1-based peptides tested here offer a potentially affordable and innovative new conceptual therapeutic paradigm that might overcome GBM stemness and invasiveness and reduce relapse rates.

Long non-coding RNAs: potential molecular biomarkers for gliomas diagnosis and prognosis

The current grade classification system of gliomas is based on the histopathological features of these tumors and has great significance in defining groups of patients for clinical assessment. However, this classification system is also associated with a number of limitations, and as such, additional clinical assessment criteria are required. Long non-coding RNAs (lncRNAs) play a critical role in cellular functions and are currently regarded as potential biomarkers for glioma diagnosis and prognosis. Therefore, the molecular classification of glioma based on lncRNA expression may provide additional information to assist in the systematic identification of glioma. In the present paper, we review the emerging evidence indicating that specific lncRNAs may have the potential for use as key novel biomarkers and thus provide a powerful tool for the systematic diagnosis of glioma.