Inhibition of NF-κB signaling ablates the invasive phenotype of glioblastoma

Copper homeostasis and cuproptosis in central nervous system diseases

Copper (Cu), an indispensable micronutrient for the sustenance of living organisms, contributes significantly to a vast array of fundamental metabolic processes. The human body maintains a relatively low concentration of copper, which is mostly found in the bones, liver, and brain. Despite its low concentration, Cu plays a crucial role as an indispensable element in the progression and pathogenesis of central nervous system (CNS) diseases. Extensive studies have been conducted in recent years on copper homeostasis and copper-induced cell death in CNS disorders, including glioma, Alzheimer's disease, Amyotrophic lateral sclerosis, Huntington's disease, and stroke. Cuproptosis, a novel copper-induced cell death pathway distinct from apoptosis, necrosis, pyroptosis, and ferroptosis, has been identified as potentially intricately linked to the pathogenic mechanisms underlying various CNS diseases. Therefore, a systematic review of copper homeostasis and cuproptosis and their relationship with CNS disorders could deepen our understanding of the pathogenesis of these diseases. In addition, it may provide new insights and strategies for the treatment of CNS disorders.

miRNA-194-3p represses NF-κB in gliomas to attenuate iPSC genes and proneural to mesenchymal transition

Severe tumor heterogeneity drives the aggressive and treatment refractory nature of glioblastomas (GBMs). While limiting GBM heterogeneity offers promising therapeutic potential, the underlying mechanisms that regulate GBM plasticity remain poorly understood. We utilized 14 patient-derived and four commercially available cell lines to uncover miR-194-3p as a key epigenetic determinant of stemness and transcriptional subtype in GBM. We demonstrate that miR-194-3p degrades TAB2, an important mediator of NF-κB activity, decreasing NF-κB transcriptional activity. The loss in NF-κB activity following miR-194-3p overexpression or TAB2 silencing decreased expression of induced pluripotent stem cell (iPSC) genes, inhibited the oncogenic IL-6/STAT3 signaling axis, suppressed the mesenchymal transcriptional subtype in relation to the proneural subtype, and induced differentiation from the glioma stem cell (GSC) to monolayer (ML) phenotype. miR-194-3p/TAB2/NF-κB signaling axis acts as an epigenetic switch that regulates GBM plasticity and targeting this signaling axis represents a potential strategy to limit transcriptional heterogeneity in GBMs.

Clinical, pharmacological, and formulation evaluation of disulfiram in the treatment of glioblastoma - a systematic literature review

INTRODUCTION

Glioblastoma (GB) is one of the most challenging central nervous system (CNS) tumors in treatment options and response, urging the development of novel management strategies. The anti-alcoholism drug, disulfiram (DS), has a potential anticancer activity, and its complex mechanism of action is assumed to be well exploited against the heterogeneous GB.

AREA COVERED

Through a systematic literature review about repositioning DS to GB treatment, an evaluation of the clinical, pharmacological, and formulation strategies is provided to specify the challenges of drug delivery and thus to advance its clinical translation. From six databases, 35 articles were selected, including case report (1); clinical trials (3); original articles mainly representing in vitro and preclinical pharmacological data, and 10 dealing with technological approaches.

EXPERT OPINION

The repositioning of DS in GB treatment is facing drug and tumor-associated limitations due to the oral drug's low bioavailability, unwanted metabolism, and inefficient delivery to brain-tumor tissue. Development strategies using molecular encapsulation of DS and the parenteral dosage forms improve the anticancer pharmacology of the drug. The development of optimized drug delivery systems (DDS) shows promise for the clinical translation of DS into GB adjuvant therapy.

Disulfiram in glioma: Literature review of drug repurposing

Gliomas are the most common malignant brain tumors. High-grade gliomas, represented by glioblastoma multiforme (GBM), have a poor prognosis and are prone to recurrence. The standard treatment strategy is tumor removal combined with radiotherapy and chemotherapy, such as temozolomide (TMZ). However, even after conventional treatment, they still have a high recurrence rate, resulting in an increasing demand for effective anti-glioma drugs. Drug repurposing is a method of reusing drugs that have already been widely approved for new indication. It has the advantages of reduced research cost, safety, and increased efficiency. Disulfiram (DSF), originally approved for alcohol dependence, has been repurposed for adjuvant chemotherapy in glioma. This article reviews the drug repurposing method and the progress of research on disulfiram reuse for glioma treatment.

EGFR ligand shifts the role of EGFR from oncogene to tumour suppressor in EGFR-amplified glioblastoma by suppressing invasion through BIN3 upregulation

The epidermal growth factor receptor (EGFR) is a prime oncogene that is frequently amplified in glioblastomas. Here we demonstrate a new tumour-suppressive function of EGFR in EGFR-amplified glioblastomas regulated by EGFR ligands. Constitutive EGFR signalling promotes invasion via activation of a TAB1-TAK1-NF-κB-EMP1 pathway, resulting in large tumours and decreased survival in orthotopic models. Ligand-activated EGFR promotes proliferation and surprisingly suppresses invasion by upregulating BIN3, which inhibits a DOCK7-regulated Rho GTPase pathway, resulting in small hyperproliferating non-invasive tumours and improved survival. Data from The Cancer Genome Atlas reveal that in EGFR-amplified glioblastomas, a low level of EGFR ligands confers a worse prognosis, whereas a high level of EGFR ligands confers an improved prognosis. Thus, increased EGFR ligand levels shift the role of EGFR from oncogene to tumour suppressor in EGFR-amplified glioblastomas by suppressing invasion. The tumour-suppressive function of EGFR can be activated therapeutically using tofacitinib, which suppresses invasion by increasing EGFR ligand levels and upregulating BIN3.

The Anti-Inflammatory Properties of Licorice (Glycyrrhiza glabra)-Derived Compounds in Intestinal Disorders

Intestinal diseases, such as inflammatory bowel diseases (IBDs) and colorectal cancer (CRC), are a significant source of morbidity and mortality worldwide. Epidemiological data have shown that IBD patients are at an increased risk for the development of CRC. IBD-associated cancer develops against a background of chronic inflammation and oxidative stress, and their products contribute to cancer development and progression. Therefore, the discovery of novel drugs for the treatment of intestinal diseases is urgently needed. Licorice (Glycyrrhiza glabra) has been largely used for thousands of years in traditional Chinese medicine. Licorice and its derived compounds possess antiallergic, antibacterial, antiviral, anti-inflammatory, and antitumor effects. These pharmacological properties aid in the treatment of inflammatory diseases. In this review, we discuss the pharmacological potential of bioactive compounds derived from Licorice and addresses their anti-inflammatory and antioxidant properties. We also discuss how the mechanisms of action in these compounds can influence their effectiveness and lead to therapeutic effects on intestinal disorders.

Diisothiocyanate-Derived Mercapturic Acids Are a Promising Partner for Combination Therapies in Glioblastoma

Glioblastoma represents the most aggressive tumor of the central nervous system. Due to invasion of glioblastoma stem cells into the healthy tissue, chemoresistance, and recurrence of the tumor, it is difficult to successfully treat glioblastoma patients, which is demonstrated by the low life expectancy of patients after standard therapy treatment. Recently, we found that diisothiocyanate-derived mercapturic acids, which are isothiocyanate derivatives from plants of the Cruciferae family, provoked a decrease in glioblastoma cell viability. These findings were extended by combining diisothiocyanate-derived mercapturic acids with dinaciclib (a small-molecule inhibitor of cyclin-dependent kinases with anti-proliferative capacity) or temozolomide (TMZ, standard chemotherapeutic agent) to test whether the components have a cytotoxic effect on glioblastoma cells when the dosage is low. Here, we demonstrate that the combination of diisothiocyanate-derived mercapturic acids with dinaciclib or TMZ had an additive or even synergistic effect in the restriction of cell growth dependent on the combination of the components and the glioblastoma cell source. This strategy could be applied to inhibit glioblastoma cell growth as a therapeutic interference of glioblastoma.

Natural Plant Compounds: Does Caffeine, Dipotassium Glycyrrhizinate, Curcumin, and Euphol Play Roles as Antitumoral Compounds in Glioblastoma Cell Lines?

Many plant-derived compounds are shown to be promising antitumor therapeutic agents by enhancing apoptosis-related pathways and cell cycle impairment in tumor cells, including glioblastoma (GBM) cell lines. We aimed to review four natural plant compounds effective in GBM cell lines as caffeine, dipotassium glycyrrhizinate (DPG), curcumin, and euphol. Furthermore, antitumoral effect of these plant compounds on GBM cell lines through microRNAs (miRs) modulation was investigated. However, only DPG and curcumin were found as effective on miR modulation. Caffeine arrests GBM cell cycle in G0/G1 phase by cyclin-dependent kinases (CDK) complex inhibition and by decreasing BCL-2 and increasing FOXO1 expression levels causing greater apoptotic activity. Caffeine can also directly inhibit IP3R3, p38 phosphorylation, and rho-associated protein kinase (ROCK), decreasing cell invasion and migration capacity or indirectly by inhibiting the tissue inhibitor metalloproteinase-1 (TIMP-1) and integrins β1 and β3, leading to lower matrix metalloproteinases, MMP-2 and MMP-9. DPG presents antitumoral effect in GBM cells related to nuclear factor kappa B (NF-κB) pathway suppression by IRAK2 and TRAF6-mediating miR-16 and miR-146a, respectively. More recently, it was observed that DPG upregulated miR-4443 and miR-3620, responsible for post-transcriptional inhibition of the NF-κB pathway by CD209 and TNC modulation, respectively leading to lower MMP-9 and migration capacity. Curcumin is able to increase miR-223-3p, miR-133a-3p, miR-181a-5p, miR-34a-5p, miR-30c-5p, and miR-1290 expression leading to serine or threonine kinase (AKT) pathway impairment and also it decreases miR-27a-5p, miR-221-3p, miR-21-5p, miR-125b-5p, and miR-151-3p expression causing p53-BCL2 pathway inhibition and consequently, cellular apoptosis. Interestingly, lower expression of miR-27a by curcumin action enhanced the C/EBP homologous protein(CHOP) expression, leading to paraptosis. Curcumin can inhibit miR-21 expression and consequently activate apoptosis through caspase 3 and death receptor (DR) 4 and 5 activation. Autophagy is controlled by the LC-3 protein that interacts with Atg family for the LC3-II formation and autophagy activation. Euphol can enhance LC3-II levels directly in GBM cells or inhibits tumor invasion and migration through PDK1 modulation.

The chick embryo chorioallantoic membrane as an experimental model to study in vivo angiogenesis in glioblastoma multiforme

Glioblastoma multiforme (GBM) represents the most aggressive form of glioma with an extremely poor prognosis, and is characterized by an intense and aberrant angiogenesis. Among the in vivo models to study tumor angiogenesis, the chick embryo chorioallantoic membrane (CAM) has been used to implant several tumor types as well as malignant cell lines to study their growth rate, angiogenic potential and metastatic capability. The aim of this article is to review the literature data concerning the use of the chick embryo CAM assay to study angiogenesis and metastatic potential in GBM. Different studies have been conducted in the past to investigate the angiogenic and metastatic potential of GBM cell lines and GBM bioptic specimens implanted onto the CAM surface or injected in the CAM circulation. Moreover, it is also possible to investigate the anti-angiogenic potential of different molecules used as anti-angiogenic drugs in the adjuvant treatment of GBM. All these studies have confirmed the utility and versatility of the CAM assay to study tumor progression of human glioblastoma. The CAM assay allows to obtain useful results that can be extrapolate to the biologic behavior of human glioblastoma.

Bcl-XL but Not Bcl-2 Is a Potential Target in Medulloblastoma Therapy

Medulloblastoma (MB) is the most common solid tumour in children and, despite current treatment with a rather aggressive combination therapy, accounts for 10% of all deaths associated with paediatric cancer. Breaking the tumour cells’ intrinsic resistance to therapy-induced cell death should lead to less aggressive and more effective treatment options. In other tumour entities, this has been achieved by modulating the balance between the various pro- and anti-apoptotic members of the Bcl-2 family with small molecule inhibitors. To evaluate the therapeutic benefits of ABT-199 (Venetoclax), a Bcl-2 inhibitor, and ABT-263 (Navitoclax), a dual Bcl-XL/Bcl-2 inhibitor, increasingly more relevant model systems were investigated. Starting from established MB cell lines, progressing to primary patient-derived material and finally an experimental tumour system imbedded in an organic environment were chosen. Assessment of the metabolic activity (a surrogate readout for population viability), the induction of DNA fragmentation (apoptosis) and changes in cell number (the combined effect of alterations in proliferation and cell death induction) revealed that ABT-263, but not ABT-199, is a promising candidate for combination therapy, synergizing with cell death-inducing stimuli. Interestingly, in the experimental tumour setting, the sensitizing effect of ABT-263 seems to be predominantly mediated via an anti-proliferative and not a pro-apoptotic effect, opening a future line of investigation. Our data show that modulation of specific members of the Bcl-2 family might be a promising therapeutic addition for the treatment of MB.

Repurposing Disulfiram for Targeting of Glioblastoma Stem Cells: An In Vitro Study

Mesenchymal glioblastoma stem cells (GSCs), a subpopulation in glioblastoma that are responsible for therapy resistance and tumor spreading in the brain, reportedly upregulate aldehyde dehydrogenase isoform-1A3 (ALDH1A3) which can be inhibited by disulfiram (DSF), an FDA-approved drug formerly prescribed in alcohol use disorder. Reportedly, DSF in combination with Cu2+ ions exerts multiple tumoricidal, chemo- and radio-therapy-sensitizing effects in several tumor entities. The present study aimed to quantify these DSF effects in glioblastoma stem cells in vitro, regarding dependence on ALDH1A3 expression. To this end, two patient-derived GSC cultures with differing ALDH1A3 expression were pretreated (in the presence of CuSO4, 100 nM) with DSF (0 or 100 nM) and the DNA-alkylating agent temozolomide (0 or 30 µM) and then cells were irradiated with a single dose of 0-8 Gy. As read-outs, cell cycle distribution and clonogenic survival were determined by flow cytometry and limited dilution assay, respectively. As a result, DSF modulated cell cycle distribution in both GSC cultures and dramatically decreased clonogenic survival independently of ALDH1A3 expression. This effect was additive to the impairment of clonogenic survival by radiation, but not associated with radiosensitization. Of note, cotreatment with temozolomide blunted the DSF inhibition of clonogenic survival. In conclusion, DSF targets GSCs independent of ALDH1A3 expression, suggesting a therapeutic efficacy also in glioblastomas with low mesenchymal GSC populations. As temozolomide somehow antagonized the DSF effects, strategies for future combination of DSF with the adjuvant standard therapy (fractionated radiotherapy and concomitant temozolomide chemotherapy followed by temozolomide maintenance therapy) are not supported by the present study.

MEST promotes lung cancer invasion and metastasis by interacting with VCP to activate NF-κB signaling

Background

Cell invasion is a hallmark of metastatic cancer, leading to unfavorable clinical outcomes. In this study, we established two highly invasive lung cancer cell models (A549-i8 and H1299-i8) and identified mesoderm-specific transcript (MEST) as a novel invasive regulator of lung cancer. We aim to characterize its biological function and clinical significance in lung cancer metastasis.

Methods

Transwell invasion assay was performed to establish high-invasive lung cancer cell model. Immunohistochemistry (IHC) was used to detect MEST expression in tumor tissues. Mass spectrometry and bioinformatic analyses were used to identify MEST-regulated proteins and binding partners. Co-immunoprecipitation assay was performed to detect the interaction of MEST and VCP. The biological functions of MEST were investigated in vitro and in vivo. Immunofluorescence staining was conducted to explore the colocalization of MEST and VCP.

Results

MEST overexpression promoted metastasis of lung cancer cells in vivo and in vitro by activating NF-κB signaling. MEST increased the interaction between VCP and IκBα, which accelerated IκBα degradation and NF-κB activation. Such acceleration was abrogated by VCP silencing, indicating that MEST is an upstream activator of the VCP/IκBα/NF-κB signaling pathway. Furthermore, high expressions of MEST and VCP were associated with poor survival of lung cancer patients.

Conclusion

Collectively, these results demonstrate that MEST plays an important role in driving invasion and metastasis of lung cancer by interacting with VCP to coordinate the IκBα/NF-κB pathway. Targeting the MEST/VCP/IκBα/NF-κB signaling pathway may be a promising strategy to treat lung cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02107-1.

Disulfiram and metformin combination anticancer effect reversible partly by antioxidant nitroglycerin and completely by NF-κB activator mebendazole in hamster fibrosarcoma

We investigated the anticancer effect of disulfiram and metformin combination on fibrosarcoma in hamsters. Hamsters of both sexes (~ 70 g) were randomly allocated to control and experimental groups (8 animals per group). In all 10 groups, 2 × 10⁶ BHK-21/C13 cells in 1 ml were injected subcutaneously into the animals' backs. Peroral treatments were carried out with disulfiram 50 mg/kg daily, or with metformin 500 mg/kg daily, or with their combination. Validation and rescue grups were treated by double doses of the single therapy and by the combination with addition of rescue daily doses of ROS inhibitor nitroglycerin 25 mg/kg or NF-κB stimulator mebendazole 460 mg/kg, via a gastric probe after tumor inoculation. After 19 days all animals were sacrificed. Blood samples were collected for hematological and biochemical analyses, the tumors were excised and weighed, and their diameters and volumes were measured. The tumor samples were pathohistologically and immunohistochemically assessed (Ki-67, PCNA, CD34, CD31, COX4, Cytochrome C, GLUT1, iNOS), and the main organs were toxicologically tested. The combination of disulfiram and metformin significantly inhibited fibrosarcoma growth in hamsters without toxicity, compared to monotherapy or control. The single treatments did not show significant antisarcoma effect. Co-treatment with nitroglycerin partly rescued tumor progression, probably by ROS inhibition, while mebendazole completely blocked anticancer activity of the disulfiram and metformin combination, most likely by NF-κB stimulation. Combination of disulfiram with metformin may be used as an effective and safe candidate for novel nontoxic adjuvant and relapse prevention anticancer therapy.

Natural Small Molecules Targeting NF-κB Signaling in Glioblastoma

Nuclear factor-κB (NF-κB) is a transcription factor that regulates various genes that mediate various cellular activities, including propagation, differentiation, motility, and survival. Abnormal activation of NF-κB is a common incidence in several cancers. Glioblastoma multiforme (GBM) is the most aggressive brain cancer described by high cellular heterogeneity and almost unavoidable relapse following surgery and resistance to traditional therapy. In GBM, NF-κB is abnormally activated by various stimuli. Its function has been associated with different processes, including regulation of cancer cells with stem-like phenotypes, invasion of cancer cells, and radiotherapy resistance identification of mesenchymal cells. Even though multimodal therapeutic approaches such as surgery, radiation therapy, and chemotherapeutic drugs are used for treating GBM, however; the estimated mortality rate for GBM patients is around 1 year. Therefore, it is necessary to find out new therapeutic approaches for treating GBM. Many studies are focusing on therapeutics having less adverse effects owing to the failure of conventional chemotherapy and targeted agents. Several studies of compounds suggested the involvement of NF-κB signaling pathways in the growth and development of a tumor and GBM cell apoptosis. In this review, we highlight the involvement of NF-κB signaling in the molecular understanding of GBM and natural compounds targeting NF-κB signaling.

Gymnema sylvestre Extract Restores the Autophagic Pathway in Human Glioblastoma Cells U87Mg

Simple Summary

The treatment of GBM is extremely difficult and complicated by the heterogeneous nature of neoplastic cells. The problems inherent in treating any central nervous system tumour are due to the anatomical complexity and the limited repair mechanisms of the surrounding unaffected tissues. The choice of the most suitable treatment for GBM depends on several factors: the location of the disease, the extent, and the nature of the tumour. The limit of this choice is mainly due to the degree of complexity of the disease and to the mechanisms of drug resistance that the neoplasm develops during the treatment. Herbal medicines and their derived phytocompounds are increasingly recognised as useful complementary treatments for cancer. Numerous clinical studies have reported the beneficial effects of herbal medicines on survival, immune modulation, and quality of life of cancer patients when used in combination with conventional therapies. In this study, we investigated all the mechanisms that control tumour cell growth after induction with Gymnema sylvestre (GS) extract and the key proteins that regulate these mechanisms in glioblastoma cells. The study is of great translational interest because the natural substances used could be proposed as natural adjuvant drugs for the treatment of glioblastoma, and therefore could act by modulating new molecular targets for the control of brain tumour cell growth.

Abstract

Glioblastoma is a brain tumour, characterised by recurrent or innate resistance to conventional chemoradiotherapy. Novel natural molecules and phyto-extracts have been proposed as adjuvants to sensitise the response to Temozolomide (TMZ). In this study, we investigated the effect of GS extract on human glioblastoma cells U87Mg. According to the IC50-values, GS extract displayed a significant cytotoxicity. This was confirmed by cell growth inhibition and alteration in metabolic activity evaluated by cell count and MTT assay. GS induced reduction in Pro-caspase 9, 3, but not PARP cleavage nor DNA fragmentation. Thus, in GS-induced cytotoxicity, cell death is not associated with apoptosis. In this context, short-term treatment of U87Mg cells with GS extract (1 mg/mL) reduced the phosphorylation levels of mTOR and of its downstream target P70 S6 kinase, highlighting the role of GS extract into autophagy induction. The activation of autophagic flux by GS extract was confirmed by Western blot analysis, which revealed the reduction in p62 and the concomitant increase in LC3B II/I ratio. Immunofluorescence evidenced the accumulation of LC3B puncta in U87Mg cells pretreated with autophagy inhibitor Bafilomycin A1. Furthermore, as main key regulators of type II programmed cell death, p53, p21 and CDK4 were also investigated and were inhibited by GS treatment. In conclusion, GS extract could be considered as an autophagy inducer in glioblastoma cells U87Mg.

Proteases Regulate Cancer Stem Cell Properties and Remodel Their Microenvironment

Proteolytic activity is perturbed in tumors and their microenvironment, and proteases also affect cancer stem cells (CSCs). CSCs are the therapy-resistant subpopulation of cancer cells with tumor-initiating capacity that reside in specialized tumor microenvironment niches. In this review, we briefly summarize the significance of proteases in regulating CSC activities with a focus on brain tumor glioblastoma. A plethora of proteases and their inhibitors participate in CSC invasiveness and affect intercellular interactions, enhancing CSC immune, irradiation, and chemotherapy resilience. Apart from their role in degrading the extracellular matrix enabling CSC migration in and out of their niches, we review the ability of proteases to modulate CSC properties, which prevents their elimination. When designing protease-oriented therapies, the multifaceted roles of proteases should be thoroughly investigated.

Advantages and disadvantages of disulfiram coadministered with popular addictive substances

Disulfiram (DSF) is a well-known anti-alcohol agent that inhibits aldehyde dehydrogenase and results in extreme 'hangover' symptoms when consumed with alcohol. This drug, however, has been suggested as useful in other forms of drug addiction due to its beneficial potential in both drug abuse reduction and withdrawal. However, among other drugs used in alcohol dependence, it carries the greatest risk of pharmacological interactions. Concomitant use of DSF and central nervous system stimulants usually leads to harmful, undesirable effects. To date, there is still limited data regarding the detailed safety profile of DSF as a concomitant drug. In this review article, we outline the current state of knowledge about DSF, its broad pharmacological action, as well as therapeutic effects, with a particular emphasis on the molecular understanding of its potential pharmacodynamic interactions with common addictive substances (e.g., alcohol, cocaine, cannabinoids, opioids) supported by relevant examples.

Molecular Mechanisms of Treatment Resistance in Glioblastoma

Glioblastoma is the most common malignant primary brain tumor in adults and is almost invariably fatal. Despite our growing understanding of the various mechanisms underlying treatment failure, the standard-of-care therapy has not changed over the last two decades, signifying a great unmet need. The challenges of treating glioblastoma are many and include inadequate drug or agent delivery across the blood-brain barrier, abundant intra- and intertumoral heterogeneity, redundant signaling pathways, and an immunosuppressive microenvironment. Here, we review the innate and adaptive molecular mechanisms underlying glioblastoma's treatment resistance, emphasizing the intrinsic challenges therapeutic interventions must overcome-namely, the blood-brain barrier, tumoral heterogeneity, and microenvironment-and the mechanisms of resistance to conventional treatments, targeted therapy, and immunotherapy.

Distinct regional ontogeny and activation of tumor associated macrophages in human glioblastoma

Tumor-associated macrophages (TAMs) constitute up to 50% of tumor bulk in glioblastoma (GBM) and play an important role in tumor maintenance and progression. The recently discovered differences between invading tumour periphery and hypoxic tumor core implies that macrophage biology is also distinct by location. This may provide further insight into the observed treatment resistance to immune modulation. We hypothesize that macrophage activation occurs through processes that are distinct in tumor periphery versus core. We therefore investigated regional differences in TAM recruitment and evolution in GBM by combining open source single cell and bulk gene expression data. We used single cell gene expression data from 4 glioblastomas (total of 3589 cells) and 122 total bulk samples obtained from 10 different patients. Cell identity, ontogeny (bone-marrow derived macrophages-BMDM vs microglia), and macrophage activation state were inferred using verified gene expression signatures. We captured the spectrum of immune states using cell trajectory analysis with pseudotime ordering. In keeping with previous studies, TAMs carrying BMDM identity were more abundant in tumor bulk while microglia-derived TAMs dominated the tumor periphery across all macrophage activation states including pre-activation. We note that core TAMs evolve towards a pro-inflammatory state and identify a subpopulation of cells based on a gene program exhibiting strong, opposing correlation with Programmed cell Death-1 (PD-1) signaling, which may correlate to their response to PD-1 inhibition. By contrast, peripheral TAMs evolve towards anti-inflammatory phenotype and contains a population of cells strongly associated with NFkB signaling. Our preliminary analysis suggests important regional differences in TAMs with regard to recruitment and evolution. We identify regionally distinct and potentially actionable cell subpopulations and advocate the need for a multi-targeted approach to GBM therapeutics.

LAPTM5-CD40 Crosstalk in Glioblastoma Invasion and Temozolomide Resistance

Background: Glioma therapy is challenged by the diffuse and invasive growth of glioma. Lysosomal protein transmembrane 5 (LAPTM5) was identified as an invasion inhibitor by an in vivo screen for invasion-associated genes. The aim of this study was to decipher the function of LAPTM5 in glioblastoma and its interaction with the CD40 receptor which is intensively evaluated as a target in the therapy of diverse cancers including glioma.

Methods: Knockdown of LAPTM5 was performed in different glioma cell lines to analyze the impact on clonogenicity, invasiveness, sensitivity to temozolomide chemotherapy, and tumorigenicity in vitro and in vivo. An expression array was used to elucidate the underlying pathways. CD40 knockdown and overexpression were induced to investigate a potential crosstalk of LAPTM5 and CD40. LAPTM5 and CD40 were correlated with the clinical outcome of glioma patients.

Results: Knockdown of LAPTM5 unleashed CD40-mediated NFκB activation, resulting in enhanced invasiveness, clonogenicity, and temozolomide resistance that was overcome by NFκB inhibition. LAPTM5 expression correlated with better overall survival in glioblastoma patients depending on CD40 expression status.

Conclusion: We conclude that LAPTM5 conveyed tumor suppression and temozolomide sensitation in CD40-positive glioblastoma through the inhibition of CD40-mediated NFκB activation. Hence, LAPTM5 may provide a potential biomarker for sensitivity to temozolomide in CD40-positive glioblastoma.

Inhibition of matrix metalloproteinase expression and cellular invasion by NF-κB inhibitors of microbial origin

Matrix metalloproteinases (MMPs) are zinc-dependent extracellular matrix remodeling endopeptidases. MMPs cleave various matrix proteins such as collagen, elastin, gelatin and casein. MMPs are often implicated in pathological processes, such as cancer progression including metastasis. Meanwhile, microorganisms produce various secondary metabolites having unique structures. We designed and synthesized dehydroxymethylepoxyquinomicin (DHMEQ) based on the structure of epoxyquinomicin C derived from Amycolatopsis as an inhibitor of NF-κB. This compound inhibited cancer cell migration and invasion. Since DHMEQ is comparatively unstable in the body, we designed and synthesized a stable DHMEQ analog, SEMBL. SEMBL also inhibited cancer cell migration and invasion. We also looked for inhibitors of cancer cell migration and invasion from microbial culture filtrates. As a result, we isolated a known compound, ketomycin, from Actinomycetes. DHMEQ, SEMBL, and ketomycin are all NF-κB inhibitors, and inhibited the expression of MMPs in the inhibition of cellular migration and invasion. These are all compounds with comparatively low toxicity, and may be useful for the development of anti-metastasis agents.

Distribution of positively charged amino acid residues in antimicrobial peptide epinecidin-1 is crucial for in vitro glioblastoma cytotoxicity and its underlying mechanisms

Epinecidin-1 (epi) was identified from orange-spotted grouper (Epinephelus coioides) and exhibits diverse biological activities. The aims of this study were to investigate how the distribution of positively charged amino acid residues affects epi-mediated cytotoxicity and to examine the molecular mechanism underlying epi-induced cytotoxicity in U87MG human glioblastoma cells. MTS/PMS and trypan blue exclusion assay were used to measure cell viability. Necrotic cell death was confirmed by detecting cyclophilin A release and propidium iodide incorporation. DNA damage was evaluated by measuring phosphorylated H2AX. Intracellular reactive oxygen species (ROS) were analyzed by flow cytometry using dihydroergotamine. Mitochondrial membrane potential was detected by flow cytometry using tetramethylrhodamine, ethyl ester. Overall, we found that epi caused cytotoxicity in U87MG cells by inducing DNA damage and necrosis through mitochondrial hyperpolarization and subsequent ROS production. The proper folding of epi into an α-helical structure was essential for epi-mediated anti-glioblastoma effects. In addition, NFκB signaling was activated in U87MG cells after exposure to epi. Suppression of NFκB further enhanced epi-induced cytotoxicity, ROS generation and DNA damage, indicating that NFκB may play a protective role in epi-induced cytotoxicity. Our findings may be useful for the design and improvement of antimicrobial peptides with anti-cancer activity.

Inhibition of Gap Junctions Sensitizes Primary Glioblastoma Cells for Temozolomide

Gap junctions have recently been shown to interconnect glioblastoma cells to a multicellular syncytial network, thereby allowing intercellular communication over long distances as well as enabling glioblastoma cells to form routes for brain microinvasion. Against this backdrop gap junction-targeted therapies might provide for an essential contribution to isolate cancer cells within the brain, thus increasing the tumor cells’ vulnerability to the standard chemotherapeutic agent temozolomide. By utilizing INI-0602—a novel gap junction inhibitor optimized for crossing the blood brain barrier—in an oncological setting, the present study was aimed at evaluating the potential of gap junction-targeted therapy on primary human glioblastoma cell populations. Pharmacological inhibition of gap junctions profoundly sensitized primary glioblastoma cells to temozolomide-mediated cell death. On the molecular level, gap junction inhibition was associated with elevated activity of the JNK signaling pathway. With the use of a novel gap junction inhibitor capable of crossing the blood–brain barrier—thus constituting an auspicious drug for clinical applicability—these results may constitute a promising new therapeutic strategy in the field of current translational glioblastoma research.

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

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

Disulfiram repurposing combined with nutritional copper supplement as add-on to chemotherapy in recurrent glioblastoma (DIRECT): Study protocol for a randomized controlled trial

Background: Disulfiram (DSF) is a well-tolerated, inexpensive, generic drug that has been in use to treat alcoholism since the 1950s. There is now independent preclinical data that supports DSF as an anticancer agent, and experimental data suggest that copper may increase its anti-neoplastic properties. There is also some clinical evidence that DSF is a promising anticancer agent in extracranial cancers. In glioblastoma, DSF induced O 6-methylguanine methyltransferase (MGMT) inhibition may increase response to alkylating chemotherapy. A recent phase I study demonstrated the safety of DSF in glioblastoma patients when DSF was administered at doses below 500 mg/day together with chemotherapy. We plan to assess the effects of DSF combined with nutritional copper supplement (DSF-Cu) as an adjuvant to alkylating chemotherapy in glioblastoma treatment. Methods: In an academic, industry independent, multicenter, open label randomized controlled phase II/III trial with parallel group design (1:1) we will assess the efficacy and safety of DSF-Cu in glioblastoma treatment. The study will include 142 patients at the time of first recurrence of glioblastoma where salvage therapy with alkylating chemotherapy is planned. Patients will be randomized to treatment with or without DSF-Cu. Primary end-point is survival at 6 months. Secondary end-points are overall survival, progression free survival, quality of life, contrast enhancing tumor volume and safety. Discussion: There is a need to improve the treatment of recurrent glioblastoma. Results from this randomized controlled trial with DSF-Cu in glioblastoma will serve as preliminary evidence of the future role of DSF-Cu in glioblastoma treatment and a basis for design and power estimations of future studies. In this publication we provide rationale for our choices and discuss methodological issues. Trial registration: The study underwent registration in EudraCT 2016-000167-16 (Date: 30.03.2016,) and Clinicaltrials.gov NCT02678975 (Date: 31.01.2016) before initiating the study.

NF-κB, Mesenchymal Differentiation and Glioblastoma

Although glioblastoma (GBM) has always been recognized as a heterogeneous tumor, the advent of largescale molecular analysis has enabled robust categorization of this malignancy into several specific subgroups. Among the subtypes designated by expression profiling, mesenchymal tumors have been associated with an inflammatory microenvironment, increased angiogenesis, and resistance to therapy. Nuclear factor-κB (NF-κB) is a ubiquitous transcription factor that plays a prominent role in mediating many of the central features associated with mesenchymal differentiation. This review summarizes the mechanisms by which NF-κB proteins and their co-regulating partners induce the transcriptional network that underlies the mesenchymal phenotype. Moreover, both the intrinsic changes within mesenchymal GBM cells and the microenvironmental factors that modify the overall NF-κB response are detailed.

Inhibition of PI3K signalling increases the efficiency of radiotherapy in glioblastoma cells

Glioblastoma, the most common primary brain tumour, is also considered one of the most lethal cancers per se. It is highly refractory to therapeutic intervention, as highlighted by the mean patient survival of only 15 months, despite an aggressive treatment approach, consisting of maximal safe surgical resection, followed by radio- and chemotherapy. Radiotherapy, in particular, can have effects on the surviving fractions of tumour cells, which are considered adverse to the desired clinical outcome: It can induce increased cellular proliferation, as well as enhanced invasion. In this study, we established that differentiated glioblastoma cells alter their DNA repair response following repeated exposure to radiation and, therefore, high single-dose irradiation (SD-IR) is not a good surrogate marker for fractionated dose irradiation (FD-IR), as used in clinical practice. Integrating irradiation into a combination therapy approach, we then investigated whether the pharmacological inhibition of PI3K signalling, the most abundantly activated survival cascade in glioblastoma, enhances the efficacy of radiotherapy. Of note, treatment with GDC-0941, which blocks PI3K-mediated signalling, did not enhance cell death upon irradiation, but both treatment modalities functioned synergistically to reduce the total cell number. Furthermore, GDC-0941 not only prevented the radiation-induced increase in the motility of the differentiated cells, but further reduced their speed below that of untreated cells. Therefore, combining radiotherapy with the pharmacological inhibition of PI3K signalling is a potentially promising approach for the treatment of glioblastoma, as it can reduce the unwanted effects on the surviving fraction of tumour cells.

Fordin: A novel type I ribosome inactivating protein from Vernicia fordii modulates multiple signaling cascades leading to anti-invasive and pro-apoptotic effects in cancer cells in vitro

Fordin, which is derived from Vernicia fordii, is a novel type I ribosome inactivating protein (RIP) with RNA N-glycosidase activity. In the present study, fordin was expressed by Escherichia coli and purified using nickel affinity chromatography. Previous studies have demonstrated RIP toxicity in a variety of cancer cell lines. To understand the therapeutic potential of fordin on tumors, the present study investigated the effects of fordin on the viability of several tumor and normal cell lines. The results demonstrated that fordin induced significant cytotoxicity in four cancer cell lines, compared with the normal cell line. Specifically, profound apoptosis and inhibition of cell invasion were observed following fordin exposure in U-2 OS and HepG2 cells; however, the molecular mechanism underlying the action of RIP remains to be fully elucidated. In the present study, it was found that the anticancer effects of fordin were associated with suppression of the nuclear factor (NF)-κB signaling pathway. In U-2 OS and HepG2 cells, fordin inhibited the expression of inhibitor of NF-κB (IκB) kinase, leading to downregulation of the phosphorylation level of IκB, which quelled the nuclear translocation of NF-κB. Fordin also reduced the mRNA and protein levels of NF-κB downstream targets associated with cell apoptosis and metastasis, particularly B-cell lymphoma-2-related protein A1 (Blf-1) and matrix metalloproteinase (MMP)-9. The inactivation of NF-κB and the reduction in the expression levels of Blf-1 and MMP-9 mediated by fordin were also confirmed by co-treatment with lipopolysaccharide or p65 small interfering RNA. These findings suggested a possible mechanism for the fordin-induced effect on tumor cell death and metastasis. The results of the present study demonstrated the multiple anticancer effects of fordin in U-2 OS and HepG2 cells, in part by inhibiting activation of the NF-κB signaling pathway.

EYA4 inhibits hepatocellular carcinoma growth and invasion by suppressing NF-κB-dependent RAP1 transactivation

Background

Our previous studies demonstrated that eyes absent homolog 4 (EYA4), a member of the eye development-related EYA family in Drosophila, is frequently methylated and silenced in hepatocellular carcinoma (HCC) specimens and associated with shorter survival. The current work aimed to explore the mechanisms through which EYA4 functions as a tumor suppressor in HCC.

Methods

Stable EYA4-expressing plasmid (pEYA4) transfectants of the human HCC cell lines Huh-7 and PLC/PRF/5 (PLC) were established. Xenografts tumors were established via subcutaneous injection of the stable transfectants into BALB/c nude mice. Tissue samples were obtained from 75 pathologically diagnosed HCC patients. Quantitative real-time polymerase chain reaction, Western blotting and immunohistochemistry were performed to determine the expression of EYA4 in cell lines, xenografts and clinical specimens. The cell proliferation, colony formation, invasiveness and tumor formation of stable transfectants were studied. A gene expression microarray was utilized to screen genes regulated by EYA4 expression. The effect of EYA4 on nuclear factor-κB (NF-κB)/RAS-related protein 1 (RAP1) signaling was demonstrated through the co-transfection of pEYA4 and Flag-tagged RAS-related protein 1A gene-expressing plasmid (Flag-RAP1A), functional studies, chromatin immunoprecipitation, immunofluorescence staining and cellular ubiquitination assay.

Results

The restoration of EYA4 expression in HCC cell lines suppressed cell proliferation, inhibited clonogenic outgrowth, reduced cell invasion and restrained xenograft tumor growth, and Flag-RAP1A reversed the suppressive effects of pEYA4 in vitro. Activation of NF-κB with tumor necrosis factor-α (TNF-α) increased the binding of p65 to the RAP1A gene promoter and up-regulated RAP1 protein expression. The inhibition of NF-κB with BAY 11-7085 and p65 siRNA successfully blocked TNF-α-induced RAP1 up-regulation. EYA4 antagonized the TNF-α-induced phosphorylation and ubiquitination of inhibitor of NF-κBα (IκBα) as well as the nuclear translocation and transactivation of p65, resulting in repressed NF-κB activity and RAP1 expression. Blocking the serine/threonine phosphatase activity of EYA4 with calyculin A notably abrogated its suppressive effect on NF-κB activity. In addition, EYA4 expression was inversely correlated with IκBα/RAP1 activity in clinical HCC specimens.

Conclusion

Our findings provide a functional and mechanistic basis for identifying EYA4 as a bona fide tumor suppressor that disrupts aberrant activation of the NF-κB/RAP1 signaling pathway and thus orchestrates a physiological impediment to HCC growth and invasion.

Blocking distinct interactions between Glioblastoma cells and their tissue microenvironment: A novel multi-targeted therapeutic approach

Due to the highly invasive nature of Glioblastoma (GB), complete surgical resection is not feasible, while motile tumour cells are often associated with several specific brain structures that enhance treatment-resistance. Here, we investigate the therapeutic potential of Disulfiram and Carbenoxolone, that inhibit two distinct interactions between GB and the brain tissue microenvironment: stress-induced cell-matrix adhesion and gap junction mediated cell-cell communication, respectively. Increase in cell numbers of tumour-initiating cells, which are cultured in suspension as cell clusters, and adherent differentiated cells can be blocked to a similar extent by Carbenoxolone, as both cell populations form gap junctions, but the adherent differentiated cells are much more sensitive to Disulfiram treatment, which - via modulation of NF-κB signalling - interferes with cell-substrate adhesion. Interestingly, inducing adhesion in tumour-initiating cells without differentiating them does not sensitize for Disulfiram. Importantly, combining Disulfiram, Carbenoxolone and the standard chemotherapeutic drug Temozolomide reduces tumour size in an orthotopic mouse model. Isolating GB cells from their direct environment within the brain represents an important addition to current therapeutic approaches. The blockage of cellular interactions via the clinically relevant substances Disulfiram and Carbenoxolone, has distinct effects on different cell populations within a tumour, potentially reducing motility and/or resistance to apoptosis.

Role of Microenvironment in Glioma Invasion: What We Learned from In Vitro Models

The invasion properties of glioblastoma hamper a radical surgery and are responsible for its recurrence. Understanding the invasion mechanisms is thus critical to devise new therapeutic strategies. Therefore, the creation of in vitro models that enable these mechanisms to be studied represents a crucial step. Since in vitro models represent an over-simplification of the in vivo system, in these years it has been attempted to increase the level of complexity of in vitro assays to create models that could better mimic the behaviour of the cells in vivo. These levels of complexity involved: 1. The dimension of the system, moving from two-dimensional to three-dimensional models; 2. The use of microfluidic systems; 3. The use of mixed cultures of tumour cells and cells of the tumour micro-environment in order to mimic the complex cross-talk between tumour cells and their micro-environment; 4. And the source of cells used in an attempt to move from commercial lines to patient-based models. In this review, we will summarize the evidence obtained exploring these different levels of complexity and highlighting advantages and limitations of each system used.

The effects of PI3K-mediated signalling on glioblastoma cell behaviour

The PI3K/Akt/mTOR signalling network is activated in almost 90% of all glioblastoma, the most common primary brain tumour, which is almost invariably lethal within 15 months of diagnosis. Despite intensive research, modulation of this signalling cascade has so far yielded little therapeutic benefit, suggesting that the role of the PI3K network as a pro-survival factor in glioblastoma and therefore a potential target in combination therapy should be re-evaluated. Therefore, we used two distinct pharmacological inhibitors that block signalling at different points of the cascade, namely, GDC-0941 (Pictilisib), a direct inhibitor of the near apical PI3K, and Rapamycin which blocks the side arm of the network that is regulated by mTOR complex 1. While both substances, at concentrations where they inhibit their primary target, have similar effects on proliferation and sensitisation for temozolomide-induced apoptosis, GDC-0941 appears to have a stronger effect on cellular motility than Rapamycin. In vivo GDC-0941 effectively retards growth of orthotopic transplanted human tumours in murine brains and significantly prolongs mouse survival. However, when looking at genetically identical cell populations that are in alternative states of differentiation, i.e. stem cell-like cells and their differentiated progeny, a more complex picture regarding the PI3K/Akt/mTOR pathway emerges. The pathway is differently regulated in the alternative cell populations and, while it contributes to the increased chemo-resistance of stem cell-like cells compared to differentiated cells, it only contributes to the motility of the latter. Our findings are the first to suggest that within a glioblastoma tumour the PI3K network can have distinct, cell-specific functions. These have to be carefully considered when incorporating inhibition of PI3K-mediated signals into complex combination therapies.

Tumor-derived fibulin-3 activates pro-invasive NF-κB signaling in glioblastoma cells and their microenvironment

Molecular profiling of glioblastomas has revealed the presence of key signaling hubs that contribute to tumor progression and acquisition of resistance. One of these main signaling mechanisms is the NF-κB pathway, which integrates multiple extracellular signals into transcriptional programs for tumor growth, invasion, and maintenance of the tumor-initiating population. We show here that an extracellular protein released by glioblastoma cells, fibulin-3, drives oncogenic NF-κB in the tumor and increases NF-κB activation in peritumoral astrocytes. Fibulin-3 expression correlates with a NF-κB-regulated “invasive signature” linked to poorer survival, being a possible tissue marker for regions of active tumor progression. Accordingly, fibulin-3 promotes glioblastoma invasion in a manner that requires NF-κB activation both in the tumor cells and their microenvironment. Mechanistically, we found that fibulin-3 activates the metalloprotease ADAM17 by competing with its endogenous inhibitor, TIMP3. This results in sustained release of soluble TNFα by ADAM17, which in turn activates TNF receptors and canonical NF-κB signaling. Taken together, our results underscore fibulin-3 as a novel extracellular signal with strong activating effect on NF-κB in malignant gliomas. Because fibulin-3 is produced de novo in these tumors and is absent from normal brain we propose that targeting the fibulin-3/NF-κB axis may provide a novel avenue to disrupt oncogenic NF-κB signaling in combination therapies for malignant brain tumors.

Cancer stem cells: The potential role of autophagy, proteolysis, and cathepsins in glioblastoma stem cells

One major obstacle in cancer therapy is chemoresistance leading to tumor recurrence and metastasis. Cancer stem cells, in particular glioblastoma stem cells, are highly resistant to chemotherapy, radiation, and immune recognition. In case of immune recognition, several survival mechanisms including, regulation of autophagy, proteases, and cell surface major histocompatibility complex class I molecules, are found in glioblastoma stem cells. In different pathways, cathepsins play a crucial role in processing functional proteins that are necessary for several processes and proper cell function. Consequently, strategies targeting these pathways in glioblastoma stem cells are promising approaches to interfere with tumor cell survival and will be discussed in this review.

Elucidation of the genetic and epigenetic landscape alterations in RNA binding proteins in glioblastoma

RNA binding proteins (RBPs) have been implicated in cancer development. An integrated bioinformatics analysis of RBPs (n = 1756) in various datasets (n = 11) revealed several genetic and epigenetically altered events among RBPs in glioblastoma (GBM). We identified 13 mutated and 472 differentially regulated RBPs in GBM samples. Mutations in AHNAK predicted poor prognosis. Copy number variation (CNV), DNA methylation and miRNA targeting contributed to RBP differential regulation. Two sets of differentially regulated RBPs that may be implicated in initial astrocytic transformation and glioma progression were identified. We have also identified a four RBP (NOL3, SUCLG1, HERC5 and AFF3) signature, having a unique expression pattern in glioma stem-like cells (GSCs), to be an independent poor prognostic indicator in GBM. RBP risk score derived from the signature also stratified GBM into low-risk and high-risk groups with significant survival difference. Silencing NOL3, SUCLG1 and HERC5 inhibited GSC maintenance. Gene set enrichment analysis of differentially regulated genes between high-risk and low-risk underscored the importance of inflammation, EMT and hypoxia in high-risk GBM. Thus, we provide a comprehensive overview of genetic and epigenetic regulation of RBPs in glioma development and progression.

EGCG inhibited bladder cancer SW780 cell proliferation and migration both in vitro and in vivo via down-regulation of NF-κB and MMP-9

Epigallocatechin-3-gallate (EGCG), the bioactive polyphenol in green tea, has been demonstrated to have various biological activities. Our study aims to investigate the antiproliferation and antimigration effects of EGCG against bladder cancer SW780 cells both in vitro and in vivo. Our results showed that treatment of EGCG resulted in significant inhibition of cell proliferation by induction of apoptosis, without obvious toxicity to normal bladder epithelium SV-HUC-1 cells. EGCG also inhibited SW780 cell migration and invasion at 25-100 μM. Western blot confirmed that EGCG induced apoptosis in SW780 cells by activation of caspases-8, -9 and -3, Bax, Bcl-2 and PARP. Besides, animal study demonstrated that EGCG [100 mg/kg, intraperitoneal (i.p.) injection daily for 3 weeks] decreased the tumor volume significantly in mice bearing SW780 tumors, as well as the tumor weight (decreased by 68.4%). In addition, EGCG down-regulated the expression of nuclear factor-kappa B (NF-κB) and matrix metalloproteinase (MMP)-9 in both protein and mRNA level in tumor and SW780 cells. When NF-κB was inhibited, EGCG showed no obvious effect in cell proliferation and migration. In conclusion, our study demonstrated that EGCG was effective in inhibition SW780 cell proliferation and migration, and presented first evidence that EGCG inhibited SW780 tumor growth by down-regulation of NF-κB and MMP-9.

KLF6 depletion promotes NF-κB signaling in glioblastoma

Dysregulation of the NF-κB transcription factor occurs in many cancer types. Krüppel-like family of transcription factors (KLFs) regulate the expression of genes involved in cell proliferation, differentiation and survival. Here, we report a new mechanism of NF-κB activation in glioblastoma through depletion of the KLF6 tumor suppressor. We show that KLF6 transactivates multiple genes negatively controlling the NF-κB pathway and consequently reduces NF-κB nuclear localization and downregulates NF-κB targets. Reconstitution of KLF6 attenuates their malignant phenotype and induces neural-like differentiation and senescence, consistent with NF-κB pathway inhibition. KLF6 is heterozygously deleted in 74.5% of the analyzed glioblastomas and predicts unfavorable patient prognosis suggesting that haploinsufficiency is a clinically relevant means of evading KLF6-dependent regulation of NF-κB. Together, our study identifies a new mechanism by which KLF6 regulates NF-κB signaling, and how this mechanism is circumvented in glioblastoma through KLF6 loss.

Inflammatory landscape of human brain tumors reveals an NFκB dependent cytokine pathway associated with mesenchymal glioblastoma

The tumor microenvironment is being increasingly recognized as a key factor in cancer aggressiveness. In this study, we characterized the inflammatory gene signatures altered in glioma cell lines and tumor specimens of differing histological and molecular subtypes. The results showed that glioblastoma multiforme (GBM) shows upregulation of a subset of inflammatory genes when compared to astrocytomas and oligodendrogliomas. With molecular subtypes of GBM, the expression of inflammatory genes is heterogeneous, being enriched in mesenchymal and downregulated in Proneural/GCIMP. Other inflammation-associated processes such as tumor-associated macrophage (TAM) signatures are upregulated in mesenchymal, and a subset of 33 mesenchymal-enriched inflammatory and TAM markers showed correlation with poor survival. We found that various GBM tumor-upregulated genes such as IL6, IL8 and CCL2 are also actively expressed in glioma cell lines, playing differential and cooperative roles in promoting proliferation, invasion, angiogenesis and macrophage polarization in vitro. These genes can be stimulated by pathways typically altered in GBM, including the EGFR, PDGFR, MEK1/2-ERK1/2, PI3K/Akt and NFκB cascades. Taken together, the results presented herein depict some inflammatory pathways altered in gliomas and highlight potentially relevant targets to therapy improvement.

Targeting Deubiquitinating Enzymes in Glioblastoma Multiforme: Expectations and Challenges

Glioblastoma (GBM) is regarded as the most common primary intracranial neoplasm. Despite standard treatment with tumor resection and radiochemotherapy, the outcome remains gloomy. It is evident that a combination of oncogenic gain of function and tumor-suppressive loss of function has been attributed to glioma initiation and progression. The ubiquitin-proteasome system is a well-orchestrated system that controls the fate of most proteins by striking a dynamic balance between ubiquitination and deubiquitination of substrates, having a profound influence on the modulation of oncoproteins, tumor suppressors, and cellular signaling pathways. In recent years, deubiquitinating enzymes (DUBs) have emerged as potential anti-cancer targets due to their targeting several key proteins involved in the regulation of tumorigenesis, apoptosis, senescence, and autophagy. This review attempts to summarize recent studies of GBM-associated DUBs, their roles in various cellular processes, and discuss the relation between DUBs deregulation and gliomagenesis, especially how DUBs regulate glioma stem cells pluripotency, microenvironment, and resistance of radiation and chemotherapy through core stem-cell transcriptional factors. We also review recent achievements and progress in the development of potent and selective reversible inhibitors of DUBs, and attempted to find a potential GBM treatment by DUBs intervention.

Biased signalling is an essential feature of TLR4 in glioma cells

A distinct feature of the Toll-like receptor 4 (TLR4) is its ability to trigger both MyD88-dependent and MyD88-independent signalling, culminating in activation of pro-inflammatory NF-κB and/or the antiviral IRF3. Although TLR4 agonists (lipopolysaccharides; LPSs) derived from different bacterial species have different endotoxic activity, the impact of LPS chemotype on the downstream signalling is not fully understood. Notably, different TLR4 agonists exhibit anti-tumoural activity in animal models of glioma, but the underlying molecular mechanisms are largely unknown. Thus, we investigated the impact of LPS chemotype on the signalling events in the human glioma cell line U251. We found that LPS of Escherichia coli origin (LPS_EC) leads to NF-κB-biased downstream signalling compared to Salmonella minnesota-derived LPS (LPS_SM). Exposure of U251 cells to LPS_EC resulted in faster nuclear translocation of the NF-κB subunit p65, higher NF-κB-activity and expression of its targets genes, and higher amount of secreted IL-6 compared to LPS_SM. Using super-resolution microscopy we showed that the biased agonism of TLR4 in glioma cells is neither a result of differential regulation of receptor density nor of formation of higher order oligomers. Consistent with previous reports, LPS_EC-mediated NF-κB activation led to significantly increased U251 proliferation, whereas LPS_SM-induced IRF3 activity negatively influenced their invasiveness. Finally, treatment with methyl-β-cyclodextrin (MCD) selectively increased LPS_SM-induced nuclear translocation of p65 and NF-κB activity without affecting IRF3. Our data may explain how TLR4 agonists differently affect glioma cell proliferation and migration.

Disulfiram when Combined with Copper Enhances the Therapeutic Effects of Temozolomide for the Treatment of Glioblastoma

PURPOSE

Glioblastoma is one of the most lethal cancers in humans, and with existing therapy, survival remains at 14.6 months. Current barriers to successful treatment include their infiltrative behavior, extensive tumor heterogeneity, and the presence of a stem-like population of cells, termed brain tumor-initiating cells (BTIC) that confer resistance to conventional therapies.

EXPERIMENTAL DESIGN

To develop therapeutic strategies that target BTICs, we focused on a repurposing approach that explored already-marketed (clinically approved) drugs for therapeutic potential against patient-derived BTICs that encompass the genetic and phenotypic heterogeneity of glioblastoma observed clinically.

RESULTS

Using a high-throughput in vitro drug screen, we found that montelukast, clioquinol, and disulfiram (DSF) were cytotoxic against a large panel of patient-derived BTICs. Of these compounds, disulfiram, an off-patent drug previously used to treat alcoholism, in the presence of a copper supplement, showed low nanomolar efficacy in BTICs including those resistant to temozolomide and the highly infiltrative quiescent stem-like population. Low dose DSF-Cu significantly augmented temozolomide activity in vitro, and importantly, prolonged in vivo survival in patient-derived BTIC models established from both newly diagnosed and recurrent tumors. Moreover, we found that in addition to acting as a potent proteasome inhibitor, DSF-Cu functionally impairs DNA repair pathways and enhances the effects of DNA alkylating agents and radiation. These observations suggest that DSF-Cu inhibits proteasome activity and augments the therapeutic effects of DNA-damaging agents (temozolomide and radiation).

CONCLUSIONS

DSF-Cu should be considered as an adjuvant therapy for the treatment of patients with glioblastoma in both newly diagnosed and recurrent settings. Clin Cancer Res; 22(15); 3860-75. ©2016 AACR.

Novel Approaches to Apoptosis-Inducing Therapies

Induction of apoptotic programmed cell death is one of the underlying principles of most current cancer therapies. In this review, we discuss the limitations and drawbacks of this approach and identify three distinct, but overlapping strategies to avoid these difficulties and further enhance the efficacy of apoptosis-inducing therapies. We postulate that the application of multi-targeted small molecule inhibitor cocktails will reduce the risk of the cancer cell populations developing resistance towards therapy. Following from these considerations regarding population genetics and ecology, we advocate the reconsideration of therapeutic end points to maximise the benefits, in terms of quantity and quality of life, for the patients. Finally, combining both previous points, we also suggest an altered focus on the cellular and molecular targets of therapy, i.e. targeting the (cancer cells') interaction with the tumour microenvironment.

A Benzochalcone Derivative, (E)-1-(2-hydroxy-6-methoxyphenyl)-3-(naphthalen-2-yl)prop-2-en-1-one (DK-512), Inhibits Tumor Invasion through Inhibition of the TNFα-Induced NF-κB/MMP-9 Axis in MDA-MB-231 Breast Cancer Cells

Tumor invasion is a critical step in tumor metastasis. In this study, we synthesized a novel benzochalcone derivative, (E)-1-(2-hydroxy-6-methoxyphenyl)-3-(naphthalen-2-yl) prop-2-en-1-one (DK-512), and characterized its effects on tumor invasion and its mechanism of action. We found that DK-512 strongly inhibited invasion of metastatic MDA-MB-231 breast cancer cells as revealed by a three-dimensional spheroid culture system. Tumor invasion and metastasis require disruption of the extracellular matrix. Matrix metalloproteinase-9 (MMP-9) is an endopeptidase that degrades extracellular matrix components. DK-512 significantly reduced tumor necrosis factor-α- (TNFα-) induced MMP-9 mRNA expression through the inhibition of RelA nuclear factor- (NF-)κB transcription factor. As our study was assessedin vitro, further works aboutin vivoefficacy of DK-512 are needed to gain further insights into whether DK-512 could be utilized as a scaffold for the development of antimetastatic agents for breast cancer.

CUSP9* treatment protocol for recurrent glioblastoma: aprepitant, artesunate, auranofin, captopril, celecoxib, disulfiram, itraconazole, ritonavir, sertraline augmenting continuous low dose temozolomide

CUSP9 treatment protocol for recurrent glioblastoma was published one year ago. We now present a slight modification, designated CUSP9*. CUSP9* drugs--aprepitant, artesunate, auranofin, captopril, celecoxib, disulfiram, itraconazole, sertraline, ritonavir, are all widely approved by regulatory authorities, marketed for non-cancer indications. Each drug inhibits one or more important growth-enhancing pathways used by glioblastoma. By blocking survival paths, the aim is to render temozolomide, the current standard cytotoxic drug used in primary glioblastoma treatment, more effective. Although esthetically unpleasing to use so many drugs at once, the closely similar drugs of the original CUSP9 used together have been well-tolerated when given on a compassionate-use basis in the cases that have come to our attention so far. We expect similarly good tolerability for CUSP9*. The combined action of this suite of drugs blocks signaling at, or the activity of, AKT phosphorylation, aldehyde dehydrogenase, angiotensin converting enzyme, carbonic anhydrase -2,- 9, -12, cyclooxygenase-1 and -2, cathepsin B, Hedgehog, interleukin-6, 5-lipoxygenase, matrix metalloproteinase -2 and -9, mammalian target of rapamycin, neurokinin-1, p-gp efflux pump, thioredoxin reductase, tissue factor, 20 kDa translationally controlled tumor protein, and vascular endothelial growth factor. We believe that given the current prognosis after a glioblastoma has recurred, a trial of CUSP9* is warranted.

Expression of TYMS in lymph node metastasis from low-grade glioma

The aim of the present study was to investigate the expression of thymidylate synthase (TYMS) in the primary foci and metastatic lymph nodes of low-grade glioma, and to analyze the function of TYMS in the lymph node metastases from low-grade glioma. The study included 93 cases of surgically resected and pathologically confirmed low-grade glioma, form patients treated at Huaihe Hospital of Henan University (Kaifeng, China). The following clinical data was obtained from each patient: Gender, age, subjective symptoms (dizziness, headache, a feeling of pressure in the head, etc.), site of disease, tumor type, pathological stage, degree of differentiation and lymph node involvement. The surgically resected gliomas and dissected cervical lymph nodes were immunohistochemically stained, and DNA was extracted from the tumor and lymph node tissues samples for polymerase chain reaction sequencing and amplification. The expression of TYMS in the primary foci and metastatic lymph nodes of low-grade glioma was examined. Additionally, the association between pathological features and the postoperative survival rate of the patients was analyzed. The primary lesions of all 93 cases exhibited positive TYMS expression and 43/157 (27.39%) lymph nodes exhibited positive TYMS expression. Factors that significantly influenced the postoperative survival rate of the patients, included the metastasis of the cervical lymph nodes (P<0.01), the number of dissected cervical lymph nodes (P<0.01) and the degree of differentiation (P<0.05). The metastasis of the cervical lymph nodes was the only independent risk factor affecting postoperative disease-free survival. The risk of recurrence in patients with metastasis of the cervical lymph nodes was 6.3-fold higher than in those without metastasis (P<0.01). Thus, the results of the present study provide a theoretical basis for accurately predicting the prognosis of patients with low-grade malignant brain glioma, reducing the conjecture involved in selecting postoperative treatment strategies and improving therapeutic efficacy.

NF-κB-dependent DNA damage-signaling differentially regulates DNA double-strand break repair mechanisms in immature and mature human hematopoietic cells

Hematopoietic stem and progenitor cells (HSPC), that is, the cell population giving rise not only to all mature hematopoietic lineages but also the presumed target for leukemic transformation, can transmit (adverse) genetic events, such as are acquired from chemotherapy or ionizing radiation. Data on the repair of DNA double-strand-breaks (DSB) and its accuracy in HSPC are scarce, in part contradictory, and mostly obtained in murine models. We explored the activity, quality and molecular components of DSB repair in human HSPC as compared with mature peripheral blood lymphocytes (PBL). To consider chemotherapy/radiation-induced compensatory proliferation, we established cycling HSPC cultures. Comparison of pathway-specific repair activities using reporter systems revealed that HSPC were severely compromised in non-homologous end joining and homologous recombination but not microhomology-mediated end joining. We observed a more pronounced radiation-induced accumulation of nuclear 53BP1 in HSPC relative to PBL, despite evidence for comparable DSB formation from cytogenetic analysis and γH2AX signal quantification, supporting differential pathway usage. Functional screening excluded a major influence of phosphatidylinositol-3-OH-kinase (ATM/ATR/DNA-PK)- and p53-signaling as well as chromatin remodeling. We identified diminished NF-κB signaling as the molecular component underlying the observed differences between HSPC and PBL, limiting the expression of DSB repair genes and bearing the risk of an inaccurate repair.