Recent advances in the treatment of malignant astrocytoma

Oncogenic long noncoding RNA LINC02283 enhances PDGF receptor A-mediated signaling and drives glioblastoma tumorigenesis

BACKGROUND

Long noncoding RNAs (lncRNAs) regulate the etiology of complex diseases and cancers, including glioblastoma (GBM). However, lncRNA-based therapies are limited because the mechanisms of action of many lncRNAs with their binding partners are not completely understood.

METHODS

We used transcriptomic and genomic data to analyze correlations between LINC02283 and PDGFRA (platelet-derived growth factor receptor A). The biological functions of the novel lncRNA were assessed in vivo using patient-derived glioma stem-like cells (GSCs), and orthotopic GBM xenografts. Immunoblotting, qRT-PCR, RNA pull down, crosslinked RNA immunoprecipitation, fluorescence in situ hybridization, and antisense oligo-mediated knockdown were performed to explore the regulation of LINC02283 on PDGFRA signaling. Expression of LINC02283 in clinical samples was assessed using pathologically diagnosed GBM patient samples.

RESULTS

We identified a novel oncogenic lncRNA, LINC02283, that is highly expressed in the PDGFRA mutation-driven cohort of glioma patients and associated with worse prognosis. LINC02283 gene co-amplifies with the PDGFRA locus and shows high correlation with PDGFRA expression. Deprivation of LINC02283 in GSCs with PDGFRA amplification mutation, attenuated tumorigenicity and enhanced survival in orthotopic GBM xenograft models, while overexpression of LINC02283 in GSCs with wild-type PDGFRA, enhances PDGFRA signaling, and decreases survival. Further, LINC02283 interacts with PDGFRA to enhance its signaling and that of its downstream targets AKT and ERK, thus promoting oncogenesis in GBM.

CONCLUSIONS

Our results provide strong evidence of LINC02283 as a regulator of PDGFRA oncogenic activity and GBM malignancy and support the potential of lncRNAs as possible therapeutic targets.

Silica nanoparticles for brain cancer

INTRODUCTION

Brain cancer is a debilitating disease with a poor survival rate. There are significant challenges for effective treatment due to the presence of the blood-brain barrier (BBB) and blood-tumor barrier (BTB) which impedes drug delivery to tumor sites. Many nanomedicines have been tested in improving both the survival and quality of life of patients with brain cancer with the recent focus on inorganic nanoparticles such as silica nanoparticles (SNPs). This review examines the use of SNPs as a novel approach for diagnosing, treating, and theranostics of brain cancer.

AREAS COVERED

The review provides an overview of different brain cancers and current therapies available. A special focus on the key functional properties of SNPs is discussed which makes them an attractive material in the field of onco-nanomedicine. Strategies to overcome the BBB using SNPs are analyzed. Furthermore, recent advancements in active targeting, combination therapies, and innovative nanotherapeutics utilizing SNPs are discussed. Safety considerations, toxicity profiles, and regulatory aspects are addressed to provide an understanding of SNPs' translational potential.

EXPERT OPINION

SNPs have tremendous prospects in brain cancer research. The multifunctionality of SNPs has the potential to overcome both the BBB and BTB limitations and can be used for brain cancer imaging, drug delivery, and theranostics. The insights provided will facilitate the development of next-generation, innovative strategies, guiding future research toward improved diagnosis, targeted therapy, and better outcomes in brain cancer patients.

RBBP4 regulates the expression of the Mre11-Rad50-NBS1 (MRN) complex and promotes DNA double-strand break repair to mediate glioblastoma chemoradiotherapy resistance

For treatment of glioblastoma (GBM), temozolomide (TMZ) and radiotherapy (RT) exert antitumor effects by inducing DNA double-strand breaks (DSBs), mainly via futile DNA mismatch repair (MMR) and inducing apoptosis. Here, we provide evidence that RBBP4 modulates glioblastoma resistance to chemotherapy and radiotherapy by recruiting transcription factors and epigenetic regulators that bind to their promoters to regulate the expression of the Mre11-Rad50-NBS1(MRN) complex and the level of DNA-DSB repair, which are closely associated with recovery from TMZ- and radiotherapy-induced DNA damage in U87MG and LN229 glioblastoma cells, which have negative MGMT expression. Disruption of RBBP4 induced GBM cell DNA damage and apoptosis in response to TMZ and radiotherapy and enhanced radiotherapy and chemotherapy sensitivity by the independent pathway of MGMT. These results displayed a possible chemo-radioresistant mechanism in MGMT negative GBM. In addition, the RBBP4-MRN complex regulation axis may provide an interesting target for developing therapy-sensitizing strategies for GBM.

Hypoxia-induced circADAMTS6 in a TDP43-dependent manner accelerates glioblastoma progression via ANXA2/ NF-κB pathway

Circular RNAs (circRNAs) play important roles in the malignant progression of tumours. Herein, we identified an unreported circRNA (hsa-circ-0072688, also named circADAMTS6) that is specifically upregulated in the hypoxic microenvironment of glioblastoma and closely correlated with poor prognosis of gliblastoma patients. We found that circADAMTS6 promotes the malignant progression of glioblastoma by promoting cell proliferation and inhibiting apoptosis. Mechanistically, the hypoxic tumour microenvironment upregulates circADAMTS6 expression through transcription factor activator protein 1 (AP-1) and RNA-binding protein TAR DNA-binding protein 43 (TDP43). Moreover, circADAMTS6 accelerates glioblastoma progression by recruiting and stabilising annexin A2 (ANXA2) in a proteasomes-dependent manner. Furthermore, we found T-5224 (AP-1 inhibitor) treatment induces downregulation of circADAMTS6 and then inhibits tumour growth. In conclusion, our findings highlight the important role of the circADAMTS6/ANXA2 axis based on hypoxic microenvironment in glioblastoma progression, as well as its regulation in NF-κB pathway. Targeting circADAMTS6 is thus expected to become a novel therapeutic strategy for glioblastoma.

Do Extent of Resection and Tumor Volume affect the Overall Survival of Anaplastic Astrocytoma? A Retrospective Study from a Single Center

Introduction: Anaplastic astrocytoma (AA) is a rare brain neoplasm that belongs to grade III gliomas according to the World Health Organization (WHO) classification. It represents only 6% of all Central Nervous System (CNS) malignancies, yet; it is associated with low survival rates. We aim to identify the survival rate after tumor resection from 10 years of experience. We also wish to determine the effect of pre and post-operative tumor volumes on the overall survival (OS). Methods: We retrospectively reviewed the records of patients with anaplastic astrocytoma who had surgery between January 2010 and January 2020. Based on Magnetic resonance imaging (MRI) results obtained < 72 hours after surgery, the Extent of Resection (EOR) was calculated by pre-op volume – post-op volume/pre-op volume*100% and classified into five categories. 1)>99% - Gross total resection (GTR) 2) 91-99% as Near-total resection (NTR) 3) 70-90% as Sub-total resection (STR) 4) <70% as Partial resection (PR) and 5) Biopsy. A multivariate proportional hazards regression analysis assessed the independent association of EOR and subsequent OS. Results: 34 patients were finally included in our analysis. The median survival time for all patients was 24.4 months, whereas the histopathological type of AA like IDH mutant was 32 months, and IDH wild type was 16.1 months as OS time. We stratified the observed survival durations for the patients according to the EOR into 5 different classes. We found that the EOR didn't affect the overall median survival. Regression analysis showed no statistically significant association between the pre or post-operative tumor volume and the OS time. Conclusion: Anaplastic astrocytoma is a tumor that carries a poor diagnosis. Gross total resection is essential to increase patients expected survival time. Unfortunately, the extent of tumor resection and tumor volume isn't correlated with the survival time for patients.

Glutamate Signaling and Filopodiagenesis of Astrocytoma Cells in Brain Cancers: Survey and Questions

Astrocytes are non-excitable cells in the CNS that can cause life-threatening astrocytoma tumors when they transform to cancerous cells. Perturbed homeostasis of the neurotransmitter glutamate is associated with astrocytoma tumor onset and progression, but the factors that govern this phenomenon are less known. Herein, we review possible mechanisms by which glutamate may act in facilitating the growth of projections in astrocytic cells. This review discusses the similarities and differences between the morphology of astrocytes and astrocytoma cells, and the role that dysregulation in glutamate and calcium signaling plays in the aberrant morphology of astrocytoma cells. Converging reports suggest that ionotropic glutamate receptors and voltage-gated calcium channels expressed in astrocytes may be responsible for the abnormal filopodiagenesis or process extension leading to astrocytoma cells’ infiltration throughout the brain.

Pulsed Microwave-Induced Thermoacoustic Shockwave for Precise Glioblastoma Therapy with the Skin and Skull Intact

Glioblastoma has a dismal prognosis and is a critical and urgent health issue that requires aggressive research and determined clinical efforts. Due to its diffuse and infiltrative growth in the brain parenchyma, complete neurosurgical resection is rarely possible. Here, pulsed microwave-induced thermoacoustic (MTA) therapy is proposed as a potential alternative modality to precisely and effectively eradicate in vivo orthotopic glioblastoma. A nanoparticle composed of polar amino acids and adenosine-based agonists is constructed with high microwave absorbance and selective penetration of the blood-brain barrier (BBB) at the tumor site. This nanoparticle can activate the adenosine receptor on the BBB to allow self-passage and tumor accumulation. The nanoparticle converts absorbed microwaves into ultrasonic shockwaves via the thermoacoustic cavitation effect. The ultrasonic shockwave can mechanically destroy tumor cells within a short range with minimal damage to adjacent normal brain tissue due to the rapid decay of the ultrasonic shockwave intensity. The deep tissue penetration characteristics of the microwave and the rapid decay of the ultrasonic shockwave make MTA therapy a promising glioblastoma cure including intact skin and skull.

Differentiation of Prostate Cancer and Stromal Hyperplasia in the Transition Zone With Monoexponential, Stretched-Exponential Diffusion-Weighted Imaging and Diffusion Kurtosis Imaging in a Reduced Number of b Values: Correlation With Whole-Mount Pathology

OBJECTIVES

The aims of the study were to explore the feasibility of generating a monoexponential model (MEM), stretched-exponential model (SEM) based diffusion-weighted imaging (DWI), and diffusion kurtosis imaging (DKI) by applying the same set of reduced b values and to compare their effectiveness in distinguishing prostate cancer from stromal hyperplasia (SH) in the transition zone (TZ) area.

METHODS

An analysis of 75 patients who underwent preoperative DWI (b values of 0, 700, 1400, 2000 s/mm2) was performed. All lesions were localized on magnetic resonance images according to whole-mount histopathological correlations. The apparent diffusion coefficient (ADC), water molecular diffusion heterogeneity index (α), distributed diffusion coefficient (DDC), mean diffusivity (MD), and mean kurtosis (MK) values were calculated and compared between the TZ cancer and SH groups. Receiver operating characteristic analysis and areas under the receiver operating characteristic curve (AUCs) were carried out for all parameters.

RESULTS

Compared with the SH group, the ADC, DDC, α, and MD values of the TZ cancer group were significantly reduced, while the MK value was significantly increased (all P < 0.05). The AUCs of the ADC, DDC, α, MD, and MK were 0.828, 0.801, 0.813, 0.822, and 0.882, respectively. The AUC of MK was significantly higher than that of the other parameters (all P < 0.05).

CONCLUSIONS

When using the reduced b-value set, all parameters from MEM, SEM, based DWI, and DKI can effectively distinguish TZ cancer from SH. Among them, DKI demonstrated potential clinical superiority over the others in TZ cancer diagnosis.

A Novel Circular RNA CircRFX3 Serves as a Sponge for MicroRNA-587 in Promoting Glioblastoma Progression via Regulating PDIA3

An increasing number of studies have indicated that circular RNAs (circRNAs) participate in the progression of numerous tumors. However, the functions of circRNAs in glioblastoma (GBM) remain largely unknown. In this study, we focused on a novel circRNA (hsa_circRFX3_003) that was spliced from RFX3, which we named circRFX3. We confirmed that the expression of circRFX3 was substantially increased in GBM cell lines and clinical GBM tissues. The results of a series of overexpression and knockdown assays indicated that circRFX3 could boost the proliferation, invasion, and migration of GBM cells. By performing dual-luciferase reporter gene and RNA pull-down assays, we verified that circRFX3 could sponge microRNA-587 (miR-587) to exercise its function as a competing endogenous RNA (ceRNA) in the development of GBM. In addition, PDIA3 was proven to be a downstream target of miR-587 and to regulate the Wnt/β-catenin pathway. In conclusion, circRFX3 could act as a cancer-promoting circRNA to boost the development of GBM and regulate the miR-587/PDIA3/β-catenin axis. This study might provide a novel target for the treatment of GBM with molecular therapy.

Recent developments in drug delivery strategies for targeting DNA damage response in glioblastoma

Glioblastoma is the most frequent and malignant brain tumor. The median survival for this disease is approximately 15 months, and despite all the available treatment strategies employed, it remains an incurable disease. Preclinical and clinical research have shown that the resistance process related to DNA damage repair pathways, glioma stem cells, blood-brain barrier selectivity, and dose-limiting toxicity of systemic treatment leads to poor clinical outcomes. In this context, the advent of drug delivery systems associated with localized treatment seems to be a promising and versatile alternative to overcome the failure of the current treatment approaches. In order to bypass therapeutic tumor resistance mechanisms, more effective combinatorial therapies should be identified, such as the use of cytotoxic drugs combined with the inhibition of DNA damage response (DDR)-related targets. Additionally, critical reasoning about the delivery approach and administration route in brain tumors treatment innovation is essential. The outcomes of future experimental studies regarding the association of delivery systems, alternative treatment routes, and DDR targets are expected to lead to the development of refined therapeutic interventions. Novel therapeutic approaches could improve the life's quality of glioblastoma patients and increase their survival rate.

EZH2 as a new therapeutic target in brain tumors: Molecular landscape, therapeutic targeting and future prospects

Brain tumors are responsible for high mortality and morbidity worldwide. The brain tumor treatment depends on identification of molecular pathways involved in progression and malignancy. Enhancer of zeste homolog 2 (EZH2) has obtained much attention in recent years in field of cancer therapy due to its aberrant expression and capacity in modulating expression of genes by binding to their promoter and affecting methylation status. The present review focuses on EZH2 signaling in brain tumors including glioma, glioblastoma, astrocytoma, ependymomas, medulloblastoma and brain rhabdoid tumors. EZH2 signaling mainly participates in increasing proliferation and invasion of cancer cells. However, in medulloblastoma, EZH2 demonstrates tumor-suppressor activity. Furthermore, EZH2 can regulate response of brain tumors to chemotherapy and radiotherapy. Various molecular pathways can function as upstream mediators of EZH2 in brain tumors including lncRNAs and miRNAs. Owing to its enzymatic activity, EZH2 can bind to promoter of target genes to induce methylation and affects their expression. EZH2 can be considered as an independent prognostic factor in brain tumors that its upregulation provides undesirable prognosis. Both anti-tumor agents and gene therapies such as siRNA have been developed for targeting EZH2 in cancer therapy.

β-elemene combined with temozolomide in treatment of brain glioma

Temozolomide (TMZ) is a widely used chemotherapeutic agent for malignant glioma. β-Elemene has been reported to have the ability of passing through the blood-brain barrier and reverse multidrug resistance. In the present study, transport of drugs through the in vitro blood-brain barrier (BBB) model also suggested that β-elemene can assist in TMZ transport to the brain. Plasma and brain pharmacokinetics demonstrated that when β-elemene is used in combination with TMZ, the metabolic rate of TMZ in plasma is slowed, and mean residence time (MRT) in brain is prolonged. The brain tissue distribution at 1 h indicated that the combination of TMZ and β-elemene promotes the distribution of β-elemene in the brain but slightly reduces the distribution of TMZ in the brain. Furthermore the antitumor effect and toxicity in vivo were also investigated. The combination of β-elemene and TMZ was well tolerated and significantly inhibited tumor growth in glioma xenografts. In summary, the present study indicates a synergistic antitumor effect of β-elemene and TMZ in glioma.

Noninvasive Differentiation of Obstructive Azoospermia and Nonobstructive Azoospermia Using Multimodel Diffusion Weighted Imaging

RATIONALE AND OBJECTIVES

To evaluate the diagnostic performance of parameters derived from multimodel diffusion weighted imaging (monoexponential, stretched-exponential diffusion weighted imaging and diffusion kurtosis imaging [DKI]) from noninvasive magnetic resonance imaging in distinguishing obstructive azoospermia (OA) from nonobstructive azoospermia (NOA).

MATERIALS AND METHODS

Forty-six patients with azoospermia were prospectively enrolled and classified into two groups (21 OA patients and 25 NOA patients). The multimodel parameters of diffusion-weighted imaging (DWI; apparent diffusion coefficient [ADC], distributed diffusion coefficient [DDC], diffusion heterogeneity [α], diffusion kurtosis diffusivity [D_app], and diffusion kurtosis coefficient [K_app]) were derived. The diagnostic performance of these parameters for the differentiation of OA and NOA patients were evaluated using receiver operating characteristic analysis. The area under the curve (AUC) was calculated to evaluate the diagnostic accuracy of each parameter.

RESULTS

All the parameters (ADC, α, DDC, D_app, and K_app) values were significantly different between OA and NOA (P < 0.001 for all). For the differentiation of OA from NOA, K_app showed the highest AUC value (0.965), followed by DDC (0.946), D_app (0.933), ADC (0.922), and α (0.887). K_app had a significantly higher AUC than the conventional ADC (P < 0.05).

CONCLUSION

Parameters derived from multimodels of DWI have the potential for the noninvasive differentiation of OA and NOA. The K_app value derived from the DKI model might serve as a useful imaging marker for the differentiation of azoospermia.

High expression of miR-195 is related to favorable prognosis in cytogenetically normal acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) is a heterogeneous blood disease with poor treatment effect and high recurrence rate. With the deepening of non-coding RNA research, more and more miRNAs have been found to participate in various physiological processes of tumors. In this study, we tried to find the miRNA related to the prognosis of AML.

METHODS

Collect gene expression data and clinical information of AML patients in the Cancer Genome Atlas database for statistical analysis. The expression level of miR-195 of each patient was standardized by logCPM and then produced as a box plot according to subtype classification. TargetScan was used to predict the target genes of miR-195, and these genes were subjected to GO pathway enrichment analysis by Metascape. Differential miRNAs were screened through the DESeq2 package in the R language. Survival rates were estimated using the Kaplan-Meier method and the log-rank test. The multivariate Cox proportional hazard models of EFS and OS were established.

RESULTS

We found that the expression of miR-195 was the lowest in cytogenetically normal (CN-) AML, and high expression of miR-195 only promoted the prognosis of chemotherapy-only CN-AML patients (EFS: P = 0.016; OS: P = 0.035). Multivariate analysis showed that miR-195^high was a favorable and independent factor for CN-AML (both P < 0.05). Further analysis showed that miR-195 may affect signal transduction through ANHAK2 in AML.

CONCLUSION

We found that high expression of miR-195 can increase prognosis time of chemotherapy-only CN-AML patients, providing a new possibility for treatment.

Difference in the malignancy between RAS and GLI1-transformed astrocytes is associated with frequency of p27KIP1-positive cells in xenograft tissues

We demonstrate that the introduction of GLI1 is sufficient for immortalized human astrocytes to be transformed whereas FOXM1 fails to induce malignant transformation, suggesting differences between GLI1 and FOXM1 in terms of transforming ability despite both transcription factors being overexpressed in malignant gliomas. Moreover, in investigations of mechanisms underlying relatively less-malignant features of GLI1-transformed astrocytes, we found that p27KIP1-positive cells were frequently observed in xenografts derived from GLI1-transformed astrocytes compared to those from RAS-transformed cells. As shRNA-mediated knockdown of p27KIP1 accelerates tumor progression of GLI1-transformed astrocytes, downregulation of p27KIP1 contributes to malignant features of transformed astrocytes. We propose that the models using immortalized/transformed astrocytes are useful to identify the minimal and most crucial set of changes required for glioma formation.

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

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

Differentiating Between Low- and High-grade Glioma Tumors Measuring Apparent Diffusion Coefficient Values in Various Regions of the Brain

Objectives

Our study aimed to apply the apparent diffusion coefficient (ADC) values to quantify the differences between low- and high-grade glioma tumors.

Methods

We conducted a multicenter, retrospective study between September to December 2019. Magnetic resonance imaging (MRI) diffusion-weighted images (DWIs), and the pathologic findings of 56 patients with glioma tumors (low grade = 28 and high grade = 28) were assessed to measure the ADC values in the tumor center, tumor edema, boundary area between tumor with normal tissue, and inside the healthy hemisphere. These values were compared between the two groups, and cut-off values were calculated using the receiver operating characteristic curve.

Results

We saw significant differences between the mean ADC values measured in the tumor center and edema between high- and low-grade tumors (p< 0.005). The ADC values in the boundary area between tumors with normal tissue and inside healthy hemisphere did not significantly differ in the groups. The ADC values at tumor center and edema were higher than 1.12 × 10^-3 mm²/s (sensitivity = 100% and specificity = 96.0%) and 1.15 × 10^-3 mm²/s (sensitivity = 75.0% and specificity = 64.0%), respectively, could be classified as low-grade tumors.

Conclusions

The ADC values from the MRI DWIs in the tumor center and edema could be used as an appropriate method for investigating the differences between low- and high-grade glioma tumors. The ADC values in the boundary area and healthy tissues had no diagnostic values in grading the glioma tumors.

A role for GLUT3 in glioblastoma cell invasion that is not recapitulated by GLUT1

The multifaceted roles of metabolism in invasion have been investigated across many cancers. The brain tumor glioblastoma (GBM) is a highly invasive and metabolically plastic tumor with an inevitable recurrence. The neuronal glucose transporter 3 (GLUT3) was previously reported to correlate with poor glioma patient survival and be upregulated in GBM cells to promote therapeutic resistance and survival under restricted glucose conditions. It has been suggested that the increased glucose uptake mediated by GLUT3 elevation promotes survival of circulating tumor cells to facilitate metastasis. Here we suggest a more direct role for GLUT3 in promoting invasion that is not dependent upon changes in cell survival or metabolism. Analysis of glioma datasets demonstrated that GLUT3, but not GLUT1, expression was elevated in invasive disease. In human xenograft derived GBM cells, GLUT3, but not GLUT1, elevation significantly increased invasion in transwell assays, but not growth or migration. Further, there were no changes in glycolytic metabolism that correlated with invasive phenotypes. We identified the GLUT3 C-terminus as mediating invasion: substituting the C-terminus of GLUT1 for that of GLUT3 reduced invasion. RNA-seq analysis indicated changes in extracellular matrix organization in GLUT3 overexpressing cells, including upregulation of osteopontin. Together, our data suggest a role for GLUT3 in increasing tumor cell invasion that is not recapitulated by GLUT1, is separate from its role in metabolism and survival as a glucose transporter, and is likely broadly applicable since GLUT3 expression correlates with metastasis in many solid tumors.

Cancer-specific loss of TERT activation sensitizes glioblastoma to DNA damage

Glioblastoma is a highly lethal form of brain cancer with no current treatment options that substantially improve patient outcomes. A key therapeutic challenge is the identification of methods that reduce tumor burden while leaving normal cells unaffected. We show that TERT-promoter mutations, common in glioblastoma, lead to TERT reactivation through increased binding of GABPB1L-isoform–containing transcription factor complexes. In turn, we find that cancer-cell–specific inhibition of TERT through GABPB1L reduction results in near-term anti-growth effects and an impaired DNA damage response that profoundly increase the sensitivity of glioblastoma tumors to frontline chemotherapy. Our results thus provide rationale for GABPB1L inhibition combined with temozolomide chemotherapy treatment as a promising therapeutic strategy for glioblastoma.

Most glioblastomas (GBMs) achieve cellular immortality by acquiring a mutation in the telomerase reverse transcriptase (TERT) promoter. TERT promoter mutations create a binding site for a GA binding protein (GABP) transcription factor complex, whose assembly at the promoter is associated with TERT reactivation and telomere maintenance. Here, we demonstrate increased binding of a specific GABPB1L-isoform–containing complex to the mutant TERT promoter. Furthermore, we find that TERT promoter mutant GBM cells, unlike wild-type cells, exhibit a critical near-term dependence on GABPB1L for proliferation, notably also posttumor establishment in vivo. Up-regulation of the protein paralogue GABPB2, which is normally expressed at very low levels, can rescue this dependence. More importantly, when combined with frontline temozolomide (TMZ) chemotherapy, inducible GABPB1L knockdown and the associated TERT reduction led to an impaired DNA damage response that resulted in profoundly reduced growth of intracranial GBM tumors. Together, these findings provide insights into the mechanism of cancer-specific TERT regulation, uncover rapid effects of GABPB1L-mediated TERT suppression in GBM maintenance, and establish GABPB1L inhibition in combination with chemotherapy as a therapeutic strategy for TERT promoter mutant GBM.

Exploring the interstitial system in the brain: the last mile of drug delivery

Brain interstitial system (ISS) is a nanoscale network of continuously connected tubes and sheets surrounding each neural cell in the central nervous system. ISS usually accounts for ∼20% of the brain volume, far more than the cerebral blood vessels, which account for 3%. The neuronal function, signaling pathways, and drug delivery are all closely related to the microenvironment provided by ISS. The objective of this paper is to give the readers a clear outline of detection, anatomy, function, and applications of ISS. This review describes the techniques propelling the exploration for ISS in chronological order, physiological function and pathological dysfunction of ISS, and strategies for drug delivery based on ISS. Biophysical features are the focus of ISS research, in which the diffusion characteristics have dominated. The various techniques that explore ISS take advantage of this feature. ISS provides an essential microenvironment for the health of cells and brain homeostasis, which plays an important functional role in brain health and disease. Direct intracranial administration allows the diffusion of drugs directly through ISS to successfully bypass the blood-brain barrier that prevents most drugs from reaching the brain. With the deepening of understanding of the brain ISS, the new research model that takes into account brain cells, cerebral vessels, and ISS will provide a new perspective and direction for understanding, utilizing, and protecting the brain.

Chromatin-regulating genes are associated with postoperative prognosis and isocitrate dehydrogenase mutation in astrocytoma

Background

Abnormality in chromatin regulation is a major determinant in the progression of multiple neoplasms. Astrocytoma is a malignant histologic morphology of glioma that is commonly accompanied by chromatin dysregulation. However, the systemic interpretation of the expression characteristics of chromatin-regulating genes in astrocytoma is unclear.

Methods

In this study, we investigated the expression profile of chromatin regulation genes in 194 astrocytoma patients sourced from The Cancer Genome Atlas (TCGA) database. The relevance of gene expression and postoperative survival outcomes was assessed.

Results

Based on the expression patterns of chromatin regulation genes, two primary clusters and three subclusters with significantly different survival outcomes were identified. The patients in cluster_1 (or subcluster_1) had a poorer prognosis than the other groups, and this particular cohort were older, with a more advanced grade of tumor and isocitrate dehydrogenase-wildtype distribution. Detection of the differentially expressed genes revealed that the group with poor prognosis was characterized by downregulation of H2AFY2, WAC, HDAC5, ZMYND11, TET1, SATB1, and MYST4, and overexpression of EYA4. Moreover, all eight genes were significantly correlated with overall survival (OS) in astrocytoma. Age-associated genes were investigated and the expression levels of EYA4, TET1, SATB1, WAC, ZMYND11, and H2AFY2 were found to be closely correlated with advanced age. Regression analysis suggested that the expression levels of H2AFY2, HILS1, EYA1, EYA4, and KDM5B were independently associated with IDH mutation status. The differential expressions of 34 common genes were significantly associated with age, grade, and IDH mutant.

Conclusions

The study revealed that the expression pattern of chromatin regulation genes was significantly associated with postoperative prognosis in astrocytoma. Moreover, the differential expression of particular genes was strongly associated with clinical characteristics such as age, grade, and IDH subtype. These results suggest that the genes involved in chromatin regulation play important roles in the biological process of astrocytoma progression, and these molecules could potentially serve as therapeutic targets in astrocytoma.

NF-κB inhibitor with Temozolomide results in significant apoptosis in glioblastoma via the NF-κB(p65) and actin cytoskeleton regulatory pathways

Glioblastoma (GBM) is the most malignant brain tumor characterized by intrinsic or acquired resistance to chemotherapy. GBM tumors show nuclear factor-κB (NF-κB) activity that has been associated with tumor formation, growth, and increased resistance to therapy. We investigated the effect of NF-κB inhibitor BAY 11-7082 with Temozolomide (TMZ) on the signaling pathways in GBM pathogenesis. GBM cells and patient-derived GBM cells cultured in 3D microwells were co-treated with BAY 11-7082 and TMZ or BAY 11-7082 and TMZ alone, and combined experiments of cell proliferation, apoptosis, wound healing assay, as well as reverse-phase protein arrays, western blot and immunofluorescence staining were used to evaluate the effects of drugs on GBM cells. The results revealed that the co-treatment significantly altered cell proliferation by decreasing GBM viability, suppressed NF-κB pathway and enhanced apoptosis. Moreover, it was found that the co-treatment of BAY 11-7082 and TMZ significantly contributed to a decrease in the migration pattern of patient-derived GBM cells by modulating actin cytoskeleton pathway. These findings suggest that in addition to TMZ treatment, NF-κB can be used as a potential target to increase the treatment's outcomes. The drug combination strategy, which is significantly improved by NF-κB inhibitor could be used to better understand the underlying mechanism of GBM pathways in vivo and as a potential therapeutic tool for GBM treatment.

Early imaging marker of progressing glioblastoma: a window of opportunity

PURPOSE

Therapeutic intervention at glioblastoma (GBM) progression, as defined by current assessment criteria, is arguably too late as second-line therapies fail to extend survival. Still, most GBM trials target recurrent disease. We propose integration of a novel imaging biomarker to more confidently and promptly define progression and propose a critical timepoint for earlier intervention to extend therapeutic exposure.

METHODS

A retrospective review of 609 GBM patients between 2006 and 2019 yielded 135 meeting resection, clinical, and imaging inclusion criteria. We qualitatively and quantitatively analyzed 2000+ sequential brain MRIs (initial diagnosis to first progression) for development of T2 FLAIR signal intensity (SI) within the resection cavity (RC) compared to the ventricles (V) for quantitative inter-image normalization. PFS and OS were evaluated using Kaplan-Meier curves stratified by SI. Specificity and sensitivity were determined using a 2 × 2 table and pathology confirmation at progression. Multivariate analysis evaluated SI effect on the hazard rate for death after adjusting for established prognostic covariates. Recursive partitioning determined successive quantifiers and cutoffs associated with outcomes. Neurological deficits correlated with SI.

RESULTS

Seventy-five percent of patients developed SI on average 3.4 months before RANO-assessed progression with 84% sensitivity. SI-positivity portended neurological decline and significantly poorer outcomes for PFS (median, 10 vs. 15 months) and OS (median, 20 vs. 29 months) compared to SI-negative. RC/V ratio ≥ 4 was the most significant prognostic indicator of death.

CONCLUSION

Implications of these data are far-reaching, potentially shifting paradigms for glioma treatment response assessment, altering timepoints for salvage therapeutic intervention, and reshaping glioma clinical trial design.

Multiple mathematical models of diffusion-weighted imaging for endometrial cancer characterization: Correlation with prognosis-related risk factors

PURPOSE

To investigate mono-exponential, bi-exponential, and stretched-exponential models of diffusion-weighted imaging (DWI) for evaluation of prognosis-related risk factors of endometrial cancer (EC).

METHOD

Sixty-one consecutive patients with EC who preoperatively underwent pelvic MRI with multiple b value DWI between September 2016 and May 2018 were enrolled. The apparent-diffusion-coefficient (ADC), bi-exponential model parameters (D, D* and f) and stretched-exponential model parameters (DDC and α) were measured and compared to analyze the following prognosis-related risk factors confirmed by pathology: histological grade, depth of myometrial invasion, cervical stromal infiltration (CSI) and lymphovascular invasion (LVSI). A stepwise multilvariate logistic regression and the receiver operating characteristic (ROC) curves were performed for further statistical analysis.

RESULTS

Lower ADC, D, f, and DDC were observed in tumor with high grade compared with a low-grade group, and the largest area under curve (AUC) was obtained when combining f and DDC values. ADC, D, f, DDC, and α were significantly different in patients with deep myometrial invasion (DMI) compared to those without DMI; the combination of f, DDC and α showed the highest AUC. Significantly different ADC and f were found between patients' presence and absence CSI; the f values showed the highest diagnostic performance with an AUC of 0.825. Regarding the LVSI, ADC, D*, f, and DDC were significantly lower in tumors with LVSI compared to those without LVSI; the combination of f and DDC showed the largest AUC.

CONCLUSION

Multiple mathematical DWI models are a useful approach for the prediction of prognosis-related risk factors in EC.

Development of an Aryloxazole Derivative as a Brain-Permeable Anti-Glioblastoma Agent

Glioblastoma drug development has been difficult due to the extremely low blood brain barrier (BBB) penetration of conventional anti-cancer agents. P-glycoprotein, an efflux membrane transporter, is responsible for the poor brain uptake of small and hydrophobic drug substances. To develop brain-penetrable anti-tumor agents, we designed colchicine derivatives containing an aryloxazole moiety, which is known to inhibit P-glycoprotein. Among those tested, an aryloxazole derivative named KIST-G1 showed the strongest anti-glioblastoma cell proliferation activity (IC₅₀ = 3.2 ± 0.8 nM). Compared to colchicine, KIST-G1 showed dramatically increased BBB-permeable properties presenting 51.7 ± 0.5 (10^-6 cm/s) parallel artificial membrane permeability assay (PAMPA) permeability and 45.0 ± 6.0% of P-gp inhibition. Aid by the BBB-permeable properties, KIST-G1 (5 mg/kg) suppressed glioblastoma cell growth and migration almost completely in the brain of glioblastoma xenograft models by showing 98.2 ± 0.1% reduced tumor area compared with phosphate buffered saline (PBS)-injected control. In comparison, temozolomide, which is the most widely used drug for glioblastoma, showed only moderate effects. Our results demonstrate the effectiveness of an aryloxazole moiety in targeting brain tumors and suggest KIST-G1 as a potent anti-glioblastoma agent.

HOXC13-AS-miR-122-5p-SATB1-C-Myc feedback loop promotes migration, invasion and EMT process in glioma

Purpose

Differentially expressed long non-coding ribonucleic acids (lncRNAs) have been reported as a key factor of glioma carcinogenesis, but the underlying mechanism involved is still unknown.

Materials and methods

In the present study, lncRNA HOXC13 antisense RNA (HOXC13-AS) was identified as a potential oncogene in glioma, and Western blotting, wound healing and Transwell assays were carried out to explore the effects of HOXC13-AS on the epithelial-mesenchymal transition (EMT) process as well as the migration and invasion of glioma cells.

Results

A further mechanistic study showed that HOXC13-AS sponged miR-122-5p to indirectly regulate SATB1 expression and affect the EMT process via the Wnt/β-catenin pathway. Meanwhile, the promoter activity was significantly increased via c-Myc, a key factor of the Wnt/β-catenin pathway, thus forming a positive HOXC13-AS-miR-122-5p-SATB1-c-Myc feedback loop to drive the malignant behavior in glioma.

Discussion

This study evidences the constitutive HOXC13-AS-miR-122-5p-SATB1-c-Myc feedback loop and provides a potential therapeutic target for glioma treatment.

Long noncoding RNA HAS2-AS1 promotes tumor progression in glioblastoma via functioning as a competing endogenous RNA

Glioblastoma multiforme (GBM) is a refractory tumor with poor prognosis and requires more effective treatment regimens. It has been confirmed that long noncoding RNAs (lncRNAs) substantially regulate various human disease including GBM. However, the biological roles and its underlying molecular mechanisms still need to be further investigated. In this study, the biological function and potential molecular mechanism of lncHAS2-AS1 in GBM were explored. It was discovered that HAS2-AS1 was elevated in glioma tissues and correlated with the prognosis of patients with glioma. Reduction of HAS2-AS1 suppressed the migration and invasion in vitro and in vivo. The transcription factor STAT1 could raise HAS2-AS1 by binding to its promoter region. Besides, HAS2-AS1 could adjust PRPS1 via sponging miR-608 in a direct manner. On the whole, the results of this study evidence that HAS2-AS1 is an oncogene and a potential therapeutic target for GBM.

circ_0001730 promotes proliferation and invasion via the miR-326/Wnt7B axis in glioma cells

Aim: To study the role of circRNA (circ_0001730) in glioblastoma. Materials & methods: The interaction between circ_0001730 and miR-326 was confirmed by FISH, RNA pull down, RNA-binding protein immunoprecipitation and luciferase reporter assays. Cell proliferation and growth were determined by MTT, EdU and colony formation assays. Cell migration was assessed by the Boyden assay. Results: The levels of circ_0001730 were elevated in glioblastoma cell lines and tissues. circ_0001730 downregulation suppressed migration and proliferation in glioblastoma cells. SP1 bounds to the promoter of circ_0001730 host gene EPHB4 thereby increasing the expression of circ_0001730. circ_0001730 activated the Wnt/β-catenin pathway via the miR-326/Wnt7B axis. Conclusion: circ_000173 promoted growth and invasion in glioblastoma cells via the miR-326/Wnt7B axis.

A New Label-Free Approach to Glioblastoma Cancer Stem Cell Sorting and Detection

Cancer stem cells (CSCs) play critical roles in cancer, making them important targets for new diagnostic and therapeutic approaches. Since CSCs are heterogeneous and not abundant in tumors, and few specific markers for these cells currently exist, new methods to isolate and characterize them are required. To address this issue, we developed a new label-free methodology to isolate, enrich, and identify CSCs from an heterogeneous tumor cell subpopulation using a cell sorting method (sedimentation field flow fractionation, SdFFF) and a biosensor as a detector. Enrichment was optimized using an original protocol and U87-MG glioblastoma cells cultured in a normal (N) or defined (D) medium (± fetal bovine serum, FBS) under normoxic (N, p_O2 = 20%) or hypoxic (H, p_O2 < 2%) conditions to obtain four cell populations: NN, NH, DN, and DH. After elution of CSCs via SdFFF using the hyperlayer mode (inertial elution mode for micrometer-sized species), we isolated eight subpopulations with distinct CSC contents based on phenotypical and functional properties, ranging from NN F1 with a lower CSC content to DH F3 with a higher CSC content. Reflecting biological differences, the intrinsic intracellular dielectric permittivity increased from NN to DH conditions. The largest difference in electromagnetic signature was observed between NN F1 and DH F3, in which the CSC content was lowest and highest, respectively. The results demonstrate that microwave dielectric spectroscopy can be used to reliably and efficiently distinguish stem cell characteristics. This new instrumental and methodological approach is an important innovation that allows both enrichment and detection of CSCs, opening the door to novel diagnostic and therapeutic approaches.

Silencing of microRNA-708 promotes cell growth and epithelial-to-mesenchymal transition by activating the SPHK2/AKT/β-catenin pathway in glioma

Aberrant microRNA-708 (miR-708) expression is frequently reported in cancer studies; however, its role in glioma has not been examined in detail. We investigated miR-708 function in glioma and revealed that miR-708 expression was significantly down-regulated in glioma tissues and cell lines. Restoration of miR-708 inhibited glioma cell growth and invasion both in vitro and in vivo. The oncogene SPHK2 (sphingosine kinase 2) was identified as a downstream target of miR-708 using luciferase and western blot assays. miR-708 inhibited AKT/β-catenin signaling, which is activated by SPHK2. In addition, we revealed that miR-708 was transcriptionally repressed by EZH2 (enhancer of zeste homolog 2)-induced histone H3 lysine 27 trimethylation and promoter methylation. In summary, our findings revealed that miR-708 is a glioma tumor suppressor and suggest that miR-708 is a potential therapeutic target for glioma patients.

ATP1A1 Integrates AKT and ERK Signaling via Potential Interaction With Src to Promote Growth and Survival in Glioma Stem Cells

Glioma stem cells (GSCs) have been considered to be responsible for treatment failure due to their self-renewal and limitless proliferative property. Recently, the Na⁺/K⁺-ATPase a1 (ATP1A1) subunit was described as a novel therapeutic target for gliomas. Interestingly, our previous proteomics study revealed that ATP1A1 is remarkably overexpressed in GSCs. In the current study, we investigated the role of ATP1A1 in regulating growth, survival, and tumorigenicity of primary human GSCs and the underlying molecular mechanism. We tested RNA and protein expression of ATP1A1 in glioma tissues and GSCs. In addition, we knocked down ATP1A1 in GSCs and assessed the effects thereof on growth, survival, and apoptosis. The role of ATP1A1 in signaling pathways was investigated in vitro. We found that the ATP1A1 expression level was associated with the grade of glioma. Knockdown of ATP1A1 in GSCs in vitro inhibited cell proliferation and survival, increased apoptosis, and halted cell-cycle progression at the G1 phase. Cell proliferation and survival were resumed upon rescue of ATP1A1 expression in ATP1A1-knockdown GSCs. The ERK1/2 and AKT pathways were inhibited through suppression of Src phosphorylation by ATP1A1 knockdown. Collectively, our findings suggest that ATP1A1 overexpression promotes GSC growth and proliferation by affecting Src phosphorylation to activate the ERK1/2 and AKT signaling pathways.

Monoexponential, Biexponential, and stretched-exponential models using diffusion-weighted imaging: A quantitative differentiation of breast lesions at 3.0T

BACKGROUND

Diffusion-weighted imaging (DWI) plays an important role in the differentiation of malignant and benign breast lesions.

PURPOSE

To investigate the utility of various diffusion parameters obtained from monoexponential, biexponential, and stretched-exponential DWI models in the differential diagnosis of breast lesions.

STUDY TYPE

Prospective.

POPULATION

Sixty-one patients (age range: 25-68 years old; mean age: 46 years old) with 31 malignant lesions, 42 benign lesions, and 28 normal breast tissues diagnosed initially by clinical palpation, ultrasonography, or conventional mammography were enrolled in the study from January to September 2016.

FIELD STRENGTH

3.0T MR scanner, T₁ WI, T₂ WI, DWI (conventional and multi-b values), dynamic contrast-enhanced.

ASSESSMENT

The apparent diffusion coefficient (ADC) was calculated by monoexponential analysis. The diffusion coefficient (ADC_slow ), pseudodiffusion coefficient (ADC_fast ), and perfusion fraction (f) were calculated using the biexponential model. The distributed diffusion coefficient (DDC) and water molecular diffusion heterogeneity index (α) were obtained using a stretched-exponential model. All parameters were compared for malignant tumors, benign tumors, and normal breast tissues. A receiver operating characteristic curve was used to compare the ability of these parameters, in order to differentiate benign and malignant breast lesions.

STATISTICAL TESTS

All statistical analyses were performed using statistical software (SPSS).

RESULTS

ADC, ADC_slow , f, DDC, and α values were significantly lower in malignant tumors when compared with normal breast tissues and benign tumors (P < 0.05). However, ADC and f had higher area under the receiver operating characteristic curve (AUC) values (0.889 and 0.919, respectively).

DATA CONCLUSION

The parameters derived from the biexponential and stretched-exponential DWI could provide additional information for differentiating between benign and malignant breast tumors when compared with conventional diffusion parameters.

LEVEL OF EVIDENCE

4 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2019;50:1461-1467.

Serum Levels of APRIL Increase in Patients with Glioma, Meningioma and Schwannoma

Objective:

Brain tumors are of high mortality and morbidity for which there is still no cure. The TNF family cytokine, A Proliferation Inducing Ligand (APRIL), is shown to help proliferation and development of tumor cells. We assessed serum levels of APRIL in patients with glioma, meningioma and schwannoma in comparison to healthy individuals.

Methods:

Peripheral blood samples of 68 patients with brain tumors, divided into three groups of gliomas (n=25), meningiomas (n=30) and schwannomas (n=13), as well as 45 healthy individuals were obtained. Serum samples were prepared and stored in -40°C until usage. Using a commercial ELISA method, APRIL concentration was measured in each serum sample. The obtained data were then analyzed using SPSS software.

Results:

APRIL serum levels were higher in all patients compared to the controls (P<0.001). Moreover, APRIL serum levels were higher in each of the tumor bearing groups (gliomas, meningiomas and schwannomas) in comparison to the controls (P<0.001, <0.001 and =0.001, respectively). Comparing APRIL between the patients groups showed no significant difference. Age and gender showed no significant correlation with serum APRIL levels, although the age of patients in glioma group was significantly lower than controls (P=0.017). The serum APRIL levels in gliomas with histological grade showed no difference, but in meningiomas, it was lower in tumors with higher grades (P= 0.011).

Conclusion:

Increased serum levels of APRIL in patients with meningioma and schwannoma as well as glioma may indicate a common role of this cytokine in brain tumors.

HPCAL1 promotes glioblastoma proliferation via activation of Wnt/β-catenin signalling pathway

Glioblastoma (GBM) is the most prevalent primary malignancy of the central nervous system with obvious aggressiveness, and is associated with poor clinical outcome. Studies have indicated that calcium ion (Ca²⁺) can positively regulate the initiation of malignancy with regard to GBM by modulating quiescence, proliferation, migration and maintenance. Hippocalcin like‐1 protein (HPCAL1) serves as a sensor of Ca²⁺. However, the understanding of HPCAL1 activity in GBM is limited. The present study revealed that the gene HPCAL1 was up‐regulated by Ca²⁺ in the tissues and cells of GBM. Ectopic expression of HPCAL1 promoted proliferation of cells. Exhaustion of HPCAL1 inhibited cell growth not only in vivo, but also in vitro. In addition, HPCAL1 enhanced the Wnt pathway by stimulating β‐catenin accumulation and nuclear translocation in GBM cells, while β‐catenin silencing significantly inhibited the proliferation and growth of the GBM cells. Our results showed that Ser9 phosphorylation of GSK3β was significantly decreased after HPCAL1 knockdown in GBM cells, and knockdown of the gene GSK3β in GBM cells enhanced cell proliferation and promoted transcription of the genes CCND1 and c‐Myc. Furthermore, the phosphorylation of ERK was decreased in the cells with HPCAL1 knockdown, while it was promoted via overexpression of HPCAL1. The suppression or depletion of the gene ERK decreased proliferation triggered by overexpression of HPCAL1 and impaired transcription of the genes c‐Myc and CCND1. These studies elucidate the tumour‐promoting activity of HPCAL1. They also offer an innovative therapeutic strategy focusing on the HPCAL1‐Wnt/β‐catenin axis to regulate proliferation and development of GBM.

PIK3CB/p110β is a selective survival factor for glioblastoma

Background

Glioblastoma (GBM) is difficult to treat. Phosphoinositide 3-kinase (PI3K) is an attractive therapeutic target for GBM; however, targeting this pathway to effectively treat GBM is not successful because the roles of PI3K isoforms remain to be defined. The aim of this study is to determine whether PIK3CB/p110β, but not other PI3K isoforms, is a biomarker for GBM recurrence and important for cell survival.

Methods

Gene expression and clinical relevance of PI3K genes in GBM patients were analyzed using online databases. Expression/activity of PI3K isoforms was determined using immunoblotting. PI3K genes were inhibited using short hairpin RNAs or isoform-selective inhibitors. Cell viability/growth was assessed by the MTS assay and trypan blue exclusion assay. Apoptosis was monitored using the caspase activity assay. Mouse GBM xenograft models were used to gauge drug efficacy.

Results

PIK3CB/p110β was the only PI3K catalytic isoform that significantly correlated with high incidence rate, risk, and poor survival of recurrent GBM. PIK3CA/p110α, PIK3CB/p110β, and PIK3CD/p110δ were differentially expressed in GBM cell lines and primary tumor cells derived from patient specimens, whereas PIK3CG/p110γ was barely detected. PIK3CB/p110β protein levels presented a stronger association with the activities of PI3K signaling than other PI3K isoforms. Blocking p110β deactivated PI3K signaling, whereas inhibition of other PI3K isoforms had no effect. Specific inhibitors of PIK3CB/p110β, but not other PI3K isoforms, remarkably suppressed viability and growth of GBM cells and xenograft tumors in mice, with minimal cytotoxic effects on astrocytes.

Conclusions

PIK3CB/p110β is a biomarker for GBM recurrence and selectively important for GBM cell survival.

Total RNA Isolation from Separately Established Monolayer and Hydrogel Cultures of Human Glioblastoma Cell Line

Astrocytoma is an invasive carcinoma occurring in the nervous system and currently lacks effective treatment options. A deeper understanding of the mechanisms of tumorigenesis and tumor progression is needed in order to develop novel therapeutic strategies. Recent advances in in vitro culture systems have demonstrated that the use of three-dimensional (3D) culture models could be more relevant for this purpose as compared to monolayer or two-dimensional (2D) models due to their resemblance to in vivo cancer pathology. High-throughput techniques such as RNA sequencing, microarray analyses and cloning could provide useful insights into the relevance of these systems to the native tissue. Previous studies have reported RNA extraction protocols needed for such applications. We have modified these protocols to suit the isolation of total RNA from monolayer and hydrogel cultures of astrocytoma established using basement membrane matrix, Geltrex™. We have used this method to demonstrate the differences in the expression of genes involved in autophagy, a process deregulated in many cancer types, in monolayer and hydrogel cultures using quantitative polymerase chain reaction (qPCR). This protocol can be adopted by the researchers who wish to understand the molecular basis of gene expression in hydrogel cultures of normal as well as cancer cell lines.

MicroRNA-770 affects proliferation and cell cycle transition by directly targeting CDK8 in glioma

Background

MicroRNAs play crucial roles in tumorigenesis and tumor progression. miR-770 has been reported to be downregulated in several cancers and affects cancer cell proliferation, apoptosis, metastasis and drug resistance. However, the role and underlying molecular mechanism of miR-770 in human glioma remain unknown and need to be further elucidated.

Methods

The expression of miR-770 in glioma tissues and cell lines was measured by quantitative real-time PCR (qRT-PCR) to explore the association of miR-770 expression with clinicopathological characteristics. The expression of CDK8 was detected by qRT-PCR and Western blotting in glioma tissues. A target prediction program and a dual-luciferase reporter assay were used to confirm that CDK8 is a target gene of miR-770. MTT and cell counting assays were used to assess the effect of miR-770 on glioma cell proliferation. The cell cycle distribution and apoptosis were examined by flow cytometry. CDK8 siRNA and overexpression were used to further confirm the function of the target gene.

Results

We demonstrated that miR-770 expression was downregulated in human glioma tissues and cell lines. The overexpression of miR-770 inhibited glioma cell proliferation and cell cycle G1-S transition and induced apoptosis. The inhibition of miR-770 facilitated cell proliferation and G1-S transition and suppressed apoptosis. miR-770 expression was inversely correlated with CDK8 expression in glioma tissues. CDK8 was confirmed to be a direct target of miR-770 by using a luciferase reporter assay. The overexpression of miR-770 decreased CDK8 expression at both the mRNA and protein levels, and the suppression of miR-770 increased CDK8 expression. Importantly, CDK8 silencing recapitulated the cellular and molecular effects observed upon miR-770 overexpression, and CDK8 overexpression eliminated the effects of miR-770 overexpression on glioma cells. Moreover, both exogenous expression of miR-770 and silencing of CDK8 resulted in suppression of the Wnt/β-catenin signaling pathway.

Conclusions

Our study demonstrates that miR-770 inhibits glioma cell proliferation and G1-S transition and induces apoptosis through suppression of the Wnt/β-catenin signaling pathway by targeting CDK8. These findings suggest that miR-770 plays a significant role in glioma progression and serves as a potential therapeutic target for glioma.

Targeting glioblastoma-derived pericytes improves chemotherapeutic outcome

Glioblastoma is the most common malignant brain cancer in adults, with poor prognosis. The blood-brain barrier limits the arrival of several promising anti-glioblastoma drugs, and restricts the design of efficient therapies. Recently, by using state-of-the-art technologies, including thymidine kinase targeting system in combination with glioblastoma xenograft mouse models, it was revealed that targeting glioblastoma-derived pericytes improves chemotherapy efficiency. Strikingly, ibrutinib treatment enhances chemotherapeutic effectiveness, by targeting pericytes, improving blood-brain barrier permeability, and prolonging survival. This study identifies glioblastoma-derived pericyte as a novel target in the brain tumor microenvironment during carcinogenesis. Here, we summarize and evaluate recent advances in the understanding of pericyte's role in the glioblastoma microenvironment.

The potential for remodelling the tumour vasculature in glioblastoma

Despite significant improvements in the clinical management of glioblastoma, poor delivery of systemic therapies to the entire population of tumour cells remains one of the biggest challenges in the achievement of more effective treatments. On the one hand, the abnormal and dysfunctional tumour vascular network largely limits blood perfusion, resulting in an inhomogeneous delivery of drugs to the tumour. On the other hand, the presence of an intact blood-brain barrier (BBB) in certain regions of the tumour prevents chemotherapeutic drugs from permeating through the tumour vessels and reaching the diseased cells. In this review we analyse in detail the implications of the presence of a dysfunctional vascular network and the impenetrable BBB on drug transport. We discuss advantages and limitations of the currently available strategies for remodelling the tumour vasculature aiming to ameliorate the above mentioned limitations. Finally we review research methods for visualising vascular dysfunction and highlight the power of DCE- and DSC-MRI imaging to assess changes in blood perfusion and BBB permeability.

Long noncoding RNA TSLNC8 suppresses cell proliferation and metastasis and promotes cell apoptosis in human glioma

Glioma is among the most common primary brain tumors and one of the most aggressive and lethal forms of human cancer. Long noncoding RNAs (lncRNAs) have demonstrated great importance in the development and progression of cancer. The present study aimed to investigate the role of the novel tumor suppressive lncRNA on Chromosome 8p12 (TSLNC8), in cell proliferation, metastasis and apoptosis in human glioma. It was initially reported that the relative transcript levels of TSLNC8 were significantly decreased in human glioma tissues and cultured glioma cells, as evidenced by RT‑qPCR. Among clinical variables, the expression of TSLNC8 was negatively associated with tumor size, distant metastasis, and tumor, node and metastasis stage. MTT assay demonstrated that overexpression of TSLNC8 in glioma cell lines U25‑MG and SWO38 decreased, whereas knockdown of TSLNC8 in glioma cells SHG‑44 and BT325 increased the cell proliferative rate over 5 consecutive days. Additionally, cell metastasis was inhibited in U251 and SWO38 cells when cells were transfected with TSLNC8‑expressing plasmid as observed via Transwell and wound‑healing assays. Furthermore, cell apoptotic rate was upregulated in TSLNC8 plasmid‑treated U251 and SWO38 cells, and inhibited by siRNA against TSLNC8 in SHG‑44 and BT325 cells by cell apoptotic assay. The relative activities of caspase‑3 and caspase‑9 were increased by TSLNC8 overexpression and decreased by TSLNC depletion; however, the activity of caspase‑8 remained unchanged. The results of the present study demonstrated the inhibitory effects of TSLNC8 in human glioma, which may contribute to advancement in the diagnosis and treatment of patients with glioma in clinic.

Overexpression of HOXC10 promotes angiogenesis in human glioma via interaction with PRMT5 and upregulation of VEGFA expression

High levels of angiogenesis are associated with poor prognosis in patients with gliomas. However, the molecular mechanisms underlying tumor angiogenesis remain unclear.

Methods: The effect of homeobox C10 (HOXC10) on tube formation, migration, and proliferation of human umbilical vein endothelial cells (HUVECs) and on chicken chorioallantoic membranes (CAMs) was examined. An animal xenograft model was used to examine the effect of HOXC10 on xenograft angiogenesis or the effect of bevacizumab, a monoclonal antibody against vascular endothelial growth factor A (VEGFA), on HOXC10-overexpressing xenografts. A chromatin immunoprecipitation assay was applied to investigate the mechanism in which HOXC10 regulated VEGFA expression.

Results: Overexpressing HOXC10 enhanced the capacity of glioma cells to induce tube formation, migration and proliferation of HUVECs, and neovascularization in CAMs, while silencing HOXC10 had the opposite result. We observed that CD31 staining was significantly increased in tumors formed by HOXC10-overexpressing U251MG cells but reduced in HOXC10-silenced tumors. Mechanistically, HOXC10 could transcriptionally upregulate VEGFA expression by binding to its promoter. Strikingly, treatment with bevacizumab, a monoclonal antibody against VEGFA, significantly inhibited the growth of HOXC10-overexpressing tumors and efficiently impaired angiogenesis. Protein arginine methyltransferase 5 (PRMT5) and WD repeat domain 5 (WDR5), both of which regulate histone post-translational modifications, were required for HOXC10-mediated VEGFA upregulation. Importantly, a significant correlation between HOXC10 levels and VEGFA expression was observed in a cohort of human gliomas.

Conclusions: This study suggests that HOXC10 induces glioma angiogenesis by transcriptionally upregulating VEGFA expression, and may represent a potential target for antiangiogenic therapy in gliomas.

Angiopep-2/IP10-EGFRvIIIscFv modified nanoparticles and CTL synergistically inhibit malignant glioblastoma

Preparation of agents that can successfully traverse the blood-brain-barrier (BBB) is a key challenge in brain cancer therapeutics. In this study, angiopep-2 was used as a brain-targeting peptide for preparing multifunctional Angiopep-2-modified poly nanoparticles, angiopep-2 and IP10-EGFRvIIIscFv fusion protein modified nanoparticles. In vitro experiments showed a greater uptake of Angiopep-2 modified nanoparticles, also angiopep-2 and IP10-EGFRvIIIscFv fusion protein modified nanoparticles by bEnd.3 cells versus nanoparticles and nanoparticles modified by IP10-EGFRvIIIscFv. Angiopep-2 and IP10-EGFRvIIIscFv fusion protein modified nanoparticles accumulated in brain tissue after intravenous injection and recruited activated CD8⁺ T lymphocytes to location of glioblastoma cells. In vivo experiments to assess anti-glioblastoma effect of angiopep-2 and IP10-EGFRvIIIscFv fusion protein modified nanoparticles showed significantly reduced tumor volume in angiopep-2 and IP10-EGFRvIIIscFv fusion protein modified nanoparticles⁺ CD8⁺ cytotoxic T lymphocytes group versus in NPs modified by IP10-EGFRvIIIscFv⁺ CD8⁺ cytotoxic T lymphocytes, CD8⁺ cytotoxic T lymphocytes, Angiopep-2 modified nanoparticles⁺ CD8⁺ cytotoxic T lymphocytes, angiopep-2 and IP10-EGFRvIIIscFv fusion protein modified nanoparticles and PBS groups. Leukocytes infiltrated in brain tissues showed strong anti-glioblastoma activity in angiopep-2 and IP10-EGFRvIIIscFv fusion protein modified nanoparticles⁺ CD8⁺ cytotoxic T lymphocytes treated mice. Thus, angiopep-2 and IP10-EGFRvIIIscFv fusion protein modified nanoparticles may be useful for brain-targeted delivery and recruitment of activated CD8⁺ T lymphocytes to glioblastoma cells.

Decreased circular RNA hsa_circ_0001649 predicts unfavorable prognosis in glioma and exerts oncogenic properties in vitro and in vivo

Glioma is a devastating disease with increasing incidence worldwide. Circular RNAs (circRNAs) was demonstrated to be involved in a wide range of pathophysiological processes, including tumorigenesis and development. Recently, the abnormally expressed hsa_circ_0001649 was found in several malignancies. In the current study, the expression levels of hsa_circ_0001649 in glioma and its clinical significance were explored. The biological functions including cell growth, colony-forming ability and apoptosis altered by hsa_circ_0001649 were further investigated in vitro. Tumor formation assay was also carried out to elucidate the oncogenic properties of hsa_circ_0001649. The data documented a decrease of hsa_circ_0001649 expression in glioma specimens and cell lines. In addition, down-regulated hsa_circ_0001649 is linked to larger tumor size (p = 0.002) and advanced WHO grade (p = 0.023). Additionally, hsa_circ_0001649 may be an independent prognostic marker for glioma patients after surgery (p = 0.046). Moreover, up-regulated hsa_circ_0001649 inhibits glioma cell growth in vitro and in vivo. Importantly, increased expression of hsa_circ_0001649 facilitates apoptosis by regulating Bcl-2/caspase-3 pathway. Ultimately, this study suggests that hsa_circ_0001649 may be a potential glioma-related prognostic/therapeutic target.

Oligosaccharyltransferase Inhibition Reduces Receptor Tyrosine Kinase Activation and Enhances Glioma Radiosensitivity

PURPOSE

Parallel signaling reduces the effects of receptor tyrosine kinase (RTK)-targeted therapies in glioma. We hypothesized that inhibition of protein N-linked glycosylation, an endoplasmic reticulum co- and posttranslational modification crucial for RTK maturation and activation, could provide a new therapeutic approach for glioma radiosensitization.Experimental Design: We investigated the effects of a small-molecule inhibitor of the oligosaccharyltransferase (NGI-1) on EGFR family receptors, MET, PDGFR, and FGFR1. The influence of glycosylation state on tumor cell radiosensitivity, chemotherapy-induced cell toxicity, DNA damage, and cell-cycle arrest were determined and correlated with glioma cell receptor expression profiles. The effects of NGI-1 on xenograft tumor growth were tested using a nanoparticle formulation validated by in vivo molecular imaging. A mechanistic role for RTK signaling was evaluated through the expression of a glycosylation-independent CD8-EGFR chimera.

RESULTS

NGI-1 reduced glycosylation, protein levels, and activation of most RTKs. NGI-1 also enhanced the radiosensitivity and cytotoxic effects of chemotherapy in those glioma cells with elevated ErbB family activation, but not in cells without high levels of RTK activation. NGI-1 radiosensitization was associated with increases in both DNA damage and G₁ cell-cycle arrest. Combined treatment of glioma xenografts with fractionated radiotherapy and NGI-1 significantly reduced tumor growth compared with controls. Expression of the CD8-EGFR eliminated the effects of NGI-1 on G₁ arrest, DNA damage, and cellular radiosensitivity, identifying RTK inhibition as the principal mechanism for the NGI-1 effect.

CONCLUSIONS

This study suggests that oligosaccharyltransferase inhibition with NGI-1 is a novel approach to radiosensitize malignant gliomas with enhanced RTK signaling.See related commentary by Wahl and Lawrence, p. 455.

Role of amino-acid PET in high-grade gliomas: limitations and perspectives

Positron emission tomography (PET) using radiolabeled amino-acids was recently recommended by the Response Assessment in Neuro-Oncology (RANO) working group as an additional tool in the diagnostic assessment of brain tumors. The aim of this review is to summarize available literature data on the role of amino-acid PET imaging in high-grade gliomas (HGGs), with regard to diagnosis, treatment planning and follow-up of these tumors. Indeed, amino-acid PET applications are multiple throughout the evolution of HGGs. However, certain limitations such as lack of specificity, uncertain value for grading and prognostication or the limited data for treatment monitoring should to be taken into account, the latter of which are further developed in this review. Notwithstanding these limitations, amino-acid PET is becoming increasingly accessible in many nuclear medicine centers. Larger prospective cohort prospective studies are thus needed in order to increase the clinical value of this modality and enable its extended use to the largest number of patients.

Methylation-mediated silencing of microRNA-211 promotes cell growth and epithelial to mesenchymal transition through activation of the AKT/β-catenin pathway in GBM

Aberrant expression of miR-211 has frequently been reported in cancer studies; however, its role in glioblastoma multiforme (GBM) has not been examined in detail. We investigated the function and the underlying mechanism of miR-211 in GBM. We revealed that miR-211 was downregulated in GBM tissues and cell lines. Restoration of miR-211 inhibited GBM cell growth and invasion both in vitro and in vivo. The epithelial to mesenchymal transition (EMT) phenotype was reversed when miR-211 expression was restored. HMGA2 was identified as a down-stream target of miR-211. MiR-211 had an inhibitory effect on AKT/β-catenin signaling, which was reversed by HMGA2 overexpression or miR-211 restoration. In addition, miR-211 was transcriptionally repressed by EZH2-induced H3K27 trimethylation and promoter methylation. Overall, our findings revealed miR-211 as a tumor suppressor in GBM and mir-211 may be a potential therapeutic target for GBM patients.

Comparison of O-(2-18F-Fluoroethyl)-L-Tyrosine Positron Emission Tomography and Perfusion-Weighted Magnetic Resonance Imaging in the Diagnosis of Patients with Progressive and Recurrent Glioma: A Hybrid Positron Emission Tomography/Magnetic Resonance Study

OBJECTIVE

To compare the diagnostic performance of O-(2-¹⁸F-fluoroethyl)-L-tyrosine (¹⁸F-FET) positron emission tomography (PET) and perfusion-weighted magnetic resonance imaging (PWI) for the diagnosis of progressive or recurrent glioma.

METHODS

Thirty-two pretreated gliomas (25 progressive or recurrent tumors, 7 treatment-related changes) were investigated with ¹⁸F-FET PET and PWI via a hybrid PET/magnetic resonance scanner. Volumes of interest with a diameter of 16 mm were centered on the maximum of abnormality in the tumor area in PET and PWI maps (relative cerebral blood volume, relative cerebral blood flow, mean transit time) and the contralateral unaffected hemisphere. Mean and maximum tumor-to-brain ratios as well as dynamic data for ¹⁸F-FET uptake were calculated. Diagnostic accuracies were evaluated by receiver operating characteristic analyses, calculating the area under the curve.

RESULTS

¹⁸F-FET PET showed a significant greater sensitivity to detect abnormalities in pretreated gliomas than PWI (76% vs. 52%, P = 0.03). The maximum tumor-to-brain ratio of ¹⁸F-FET PET was the only parameter that discriminated treatment-related changes from progressive or recurrent gliomas (area under the curve, 0.78; P = 0.03, best cut-off 2.61; sensitivity 80%, specificity 86%, accuracy 81%). Among patients with signal abnormality in both modalities, 75% revealed spatially incongruent local hot spots.

CONCLUSIONS

This pilot study suggests that ¹⁸F-FET PET is superior to PWI to diagnose progressive or recurrent glioma.

Prognostic Implication of Clinical and Pathologic Features in Patients with Glioblastoma Multiforme Treated with Concomitant Radiation plus Temozolomide

Aims and background

Glioblastoma multiforme is the most common and most malignant primary brain tumor in adults. The current standard of care for glioblastoma is surgical resection to the extent feasible, followed by adjuvant radiotherapy plus temozolomide, given concomitantly with and after radiotherapy. This report is a prospective observational study of 43 cases treated in the Department of Radiotherapy, University of Rome La Sapienza, Italy. We examine the relationship between pathologic features and objective response rate in adult patients treated with concomitant radiation plus temozolomide to identify clinical, neuroradiologic, pathologic, and molecular factors with prognostic significance.

Methods

Forty-three consecutive patients (24 males and 19 females), ages 15-77 years (median, 57) with newly diagnosed glioblastoma multiforme, were included in this trial between 2002 and 2004 at our department. All patients were treated with surgery (complete resection in 81%, incomplete in 19%) followed by concurrent temozolomide (75 mg/m2/day) and radiotherapy (median tumor dose, 60 Gy), followed by temozolomide, 200 mg/m2/day for 5 consecutive days every 28 days. Neurologic evaluations were performed monthly and cranial magnetic resonance bimonthly. We analyzed age, clinical manifestations at diagnosis, seizures, Karnofsky performance score, tumor location, extent of resection, proliferation index (Ki-67 expression), p53, platelet-derived growth factor and epidermal growth factor receptor immunohistochemical expression as prognostic factors in the patients. The Kaplan-Meier statistical method and logrank test were used to assess correlation with survival.

Results

Fourteen patients (32%) manifested clinical and neuroradiographic evidence of tumor progression within 6 months of surgery. In contrast, 5 patients (12%) showed no disease progression for 18 months from the beginning of treatment. Median overall survival was 19 months. Multivariate analysis revealed that an age of 60 years or older (P <0.03), a postoperative performance score ≤70 (P = 0.04), the nontotal tumor resection (P = 0.03), tumor size >4 cm (P = 0.01) and proliferation index overexpression (P = 0.001) were associated with the worst prognosis. p53, PDGF and EGFR overexpression were not significant prognostic factors associated with survival.

Conclusions

The results suggest that analysis of prognostic markers in glioblastoma multiforme is complex. In addition to previously recognized prognostic variables such as age and Karnofsky performance score, tumor size, total resection and proliferation index overexpression were identified as predictors of survival in a series of patients with glioblastoma multiforme.

A comparison between oral chemotherapy combined with radiotherapy and radiotherapy for newly diagnosed glioblastoma: A systematic review and meta-analysis

The prognosis of glioblastoma (GBM), a major subtype of grade IV glioma, is rather poor nowadays. The efficiency of chemotherapy serving as the adjunct to radiotherapy (RT) for treating GBM is still controversial. In this study, we aim to investigate the overall survival (OS) and progression-free survival (PFS) in patients with newly diagnosed GBM received RT plus chemotherapy or with RT alone.Literatures were searched from the PubMed, Embase, and Cochrane Library between January 2001 and June 2015. Study selection was conducted based on the following criteria: randomized clinical trial (RCT) of adjuvant RT plus chemotherapy versus RT alone; studies comparing OS and/or PFS; and studies including cases medically confirmed of newly diagnosed GBM.Five RCTs (1655 patients) were eligible in this study. The meta-analysis showed a significant improvement in OS of patients treated with RT plus oral chemotherapy compared with that of RT alone (hazard ratio 0.70; 95% confidence interval, 0.56-0.88, P = .002).Adjuvant chemotherapy confers a survival benefit in patients newly diagnosed with GBM.