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

Recurrent Glioblastoma-Molecular Underpinnings and Evolving Treatment Paradigms

Glioblastoma is the most common and lethal central nervous system malignancy with a median survival after progression of only 6-9 months. Major biochemical mechanisms implicated in glioblastoma recurrence include aberrant molecular pathways, a recurrence-inducing tumor microenvironment, and epigenetic modifications. Contemporary standard-of-care (surgery, radiation, chemotherapy, and tumor treating fields) helps to control the primary tumor but rarely prevents relapse. Cytoreductive treatment such as surgery has shown benefits in recurrent glioblastoma; however, its use remains controversial. Several innovative treatments are emerging for recurrent glioblastoma, including checkpoint inhibitors, chimeric antigen receptor T cell therapy, oncolytic virotherapy, nanoparticle delivery, laser interstitial thermal therapy, and photodynamic therapy. This review seeks to provide readers with an overview of (1) recent discoveries in the molecular basis of recurrence; (2) the role of surgery in treating recurrence; and (3) novel treatment paradigms emerging for recurrent glioblastoma.

The Role of Mesenchymal Reprogramming in Malignant Clonal Evolution and Intra-Tumoral Heterogeneity in Glioblastoma

Glioblastoma (GBM) is the most common yet uniformly fatal adult brain cancer. Intra-tumoral molecular and cellular heterogeneities are major contributory factors to therapeutic refractoriness and futility in GBM. Molecular heterogeneity is represented through molecular subtype clusters whereby the proneural (PN) subtype is associated with significantly increased long-term survival compared to the highly resistant mesenchymal (MES) subtype. Furthermore, it is universally recognized that a small subset of GBM cells known as GBM stem cells (GSCs) serve as reservoirs for tumor recurrence and progression. The clonal evolution of GSC molecular subtypes in response to therapy drives intra-tumoral heterogeneity and remains a critical determinant of GBM outcomes. In particular, the intra-tumoral MES reprogramming of GSCs using current GBM therapies has emerged as a leading hypothesis for therapeutic refractoriness. Preventing the intra-tumoral divergent evolution of GBM toward the MES subtype via new treatments would dramatically improve long-term survival for GBM patients and have a significant impact on GBM outcomes. In this review, we examine the challenges of the role of MES reprogramming in the malignant clonal evolution of glioblastoma and provide future perspectives for addressing the unmet therapeutic need to overcome resistance in GBM.

HSPA5 and FGFR1 genes in the mesenchymal subtype of glioblastoma can improve a treatment efficacy

Tyrosine kinase inhibitors (TKIs) have emerged as a potential treatment strategy for glioblastoma multiforme (GBM). However, their efficacy is limited by various drug resistance mechanisms. To devise more effective treatments for GBM, genetic characteristics must be considered in addition to pre-existing treatments. We performed an integrative analysis with heterogeneous GBM datasets of genomic, transcriptomic, and proteomic data from DepMap, TCGA and CPTAC. We found that poor prognosis was induced by co-upregulation of heat shock protein family A member 5 (HSPA5) and fibroblast growth factor receptor 1 (FGFR1). Co-up regulation of these two genes could regulate the PI3K/AKT pathway. GBM cell lines with co-upregulation of these two genes showed higher drug sensitivity to PI3K inhibitors. In the mesenchymal subtype, the co-upregulation of FGFR1 and HSPA5 resulted in the most malignant subtype of GBM. Furthermore, we found this newly discovered subtype was correlated with homologous recombination deficiency (HRD) In conclusion, we discovered novel druggable candidates within the group exhibiting co-upregulation of these two genes in GBM, suggest potential strategies for combination therapy.

Crosstalk between vault RNAs and innate immunity

PURPOSE

Vault (vt) RNAs are noncoding (nc) RNAs transcribed by RNA polymerase III (RNA Pol III) with 5'-triphosphate (5'-PPP) termini that play significant roles and are recognized by innate immune sensors, including retinoic acid-inducible protein 1 (RIG-I). In addition, vtRNAs adopt secondary structures that can be targets of interferon-inducible protein kinase R (PKR) and the oligoadenylate synthetase (OAS)/RNase L system, both of which are important for activating antiviral defenses. However, changes in the expression of vtRNAs have been associated with pathological processes that activate proinflammatory pathways, which influence cellular events such as differentiation, aging, autophagy, apoptosis, and drug resistance in cancer cells.

RESULTS

In this review, we summarized the biology of vtRNAs and focused on their interactions with the innate immune system. These findings provide insights into the diverse roles of vtRNAs and their correlation with various cellular processes to improve our understanding of their biological functions.

"Don't let it to air": A cautionary tale of the potential consequences of surgery of residual cancer

In this issue of the BBI, Haldar et al. demonstrate that major surgical stress from laparotomy caused a significant increase in post-operative metastatic burden in a mouse model of cancer. They identified this metastatic outbreak was driven by a novel mechanism of direct, surgery-induced activation of the primary tumour which, if left in situ, released pro-metastatic factors (IL-6, IL-8, and VEGF). Surgical stress induced significant changes in the transcriptional programming of the primary tumor, with marked activation of NF-κB and down-regulation of IRF-1. Pharmaceutical blockade of post-operative β-adrenergic and prostanoid signalling, by administration of propranolol and etodolac, prevented post-operative activation of the primary tumour and metastatic disease.

Combining Pr3+-Doped Nanoradiosensitizers and Endogenous Protoporphyrin IX for X-ray-Mediated Photodynamic Therapy of Glioblastoma Cells

Glioblastoma multiforme is an aggressive type of brain cancer with high recurrence rates due to the presence of radioresistant cells remaining after tumor resection. Here, we report the development of an X-ray-mediated photodynamic therapy (X-PDT) system using NaLuF₄:25% Pr³⁺ radioluminescent nanoparticles in conjunction with protoporphyrin IX (PPIX), an endogenous photosensitizer that accumulates selectively in cancer cells. Conveniently, 5-aminolevulinic acid (5-ALA), the prodrug that is administered for PDT, is the only drug approved for fluorescence-guided resection of glioblastoma, enabling dual detection and treatment of malignant cells. NaLuF₄:Pr³⁺ nanoparticles were synthesized and spectroscopically evaluated at a range of Pr³⁺ concentrations. This generated radioluminescent nanoparticles with strong emissions from the ¹S₀ excited state of Pr³⁺, which overlaps with the Soret band of PPIX to perform photodynamic therapy. The spectral overlap between the nanoparticles and PPIX improved treatment outcomes for U251 cells, which were used as a model for the thin tumor margin. In addition to sensitizing PPIX to induce X-PDT, our nanoparticles exhibit strong radiosensitizing properties through a radiation dose-enhancement effect. We evaluate the effects of the nanoparticles alone and in combination with PPIX on viability, death, stress, senescence, and proliferation. Collectively, our results demonstrate this as a strong proof of concept for nanomedicine.

Gut microbiota in brain tumors: An emerging crucial player

In recent decades, various roles of the gut microbiota in physiological and pathological conditions have been uncovered. Among the many interacting pathways between the host and gut flora, the gut-brain axis has drawn increasing attention and is generally considered a promising way to understand and treat brain tumors, one of the most lethal neoplasms. In this narrative review, we aimed to unveil and dissect the sophisticated mechanisms by which the gut-brain axis exerts its influence on brain tumors. Furthermore, we summarized the latest research regarding the gastrointestinal microbial landscape and the effect of gut-brain axis malfunction on different brain tumors. Finally, we outlined the ongoing developing approaches of microbial manipulation and their corresponding research related to neuro-malignancies. Collectively, we recapitulated the advances in gut microbial alterations along with their potential interactive mechanisms in brain tumors and encouraged increased efforts in this area.

Integrated transcriptomics and proteomics data analysis identifies CDH17 as a key cell surface target in colorectal cancer

Immunotherapy development against colorectal cancer (CRC) is hindered by the lack of cell surface target highly expressed in cancer cells but with restricted presence in normal tissues to minimize off-tumor toxicities. In this in silico analysis, a longlist of genes (n = 13,488) expressed in CRCs according to the Human Protein Atlas (HPA) database were evaluated to shortlist for potential surface targets based on the following prerequisites: (i) Absent from the brain and lung tissues to minimize the likelihood of neurologic and pulmonary toxicities; (ii) Restricted expression profile in other normal human tissues; (iii) Genes that potentially encode cell surface proteins and; (iv) At least moderately expressed in CRC cases. Fifteen potential targets were shortlisted and subsequently ranked according to the combination of their transcript and protein expression levels in CRCs derived from multiple datasets (i.e. DepMap, TCGA, CPTAC-2, and HPA CRCs). The top-ranked target with the highest and homogenous expression in CRCs was cadherin 17 (CDH17). Downstream analysis of CRC transcriptomics and proteomics datasets showed that CDH17 was significantly correlated with carcinoembryonic antigen expression. Moreover, CDH17 expression was significantly lower in CRC cases with high microsatellite instability, as well as negatively associated with immune response gene sets and the expression of MHC class I and II molecules. CDH17 represents an optimal target for therapeutic development against CRCs, and this study provides a novel framework to identify key cell surface targets for therapeutic development against other malignancies.

Transcriptional Regulation during Aberrant Activation of NF-κB Signalling in Cancer

The NF-κB signalling pathway is a major signalling cascade involved in the regulation of inflammation and innate immunity. It is also increasingly recognised as a crucial player in many steps of cancer initiation and progression. The five members of the NF-κB family of transcription factors are activated through two major signalling pathways, the canonical and non-canonical pathways. The canonical NF-κB pathway is prevalently activated in various human malignancies as well as inflammation-related disease conditions. Meanwhile, the significance of non-canonical NF-κB pathway in disease pathogenesis is also increasingly recognized in recent studies. In this review, we discuss the double-edged role of the NF-κB pathway in inflammation and cancer, which depends on the severity and extent of the inflammatory response. We also discuss the intrinsic factors, including selected driver mutations, and extrinsic factors, such as tumour microenvironment and epigenetic modifiers, driving aberrant activation of NF-κB in multiple cancer types. We further provide insights into the importance of the interaction of NF-κB pathway components with various macromolecules to its role in transcriptional regulation in cancer. Finally, we provide a perspective on the potential role of aberrant NF-κB activation in altering the chromatin landscape to support oncogenic development.

Epigenetic Underpinnings of Inflammation: A Key to Unlock the Tumor Microenvironment in Glioblastoma

Glioblastoma (GBM) is the most common malignant brain tumor in adults, and immunotherapies and genetic therapies for GBM have evolved dramatically over the past decade, but GBM therapy is still facing a dilemma due to the high recurrence rate. The inflammatory microenvironment is a general signature of tumors that accelerates epigenetic changes in GBM and helps tumors avoid immunological surveillance. GBM tumor cells and glioma-associated microglia/macrophages are the primary contributors to the inflammatory condition, meanwhile the modification of epigenetic events including DNA methylation, non-coding RNAs, and histone methylation and deacetylases involved in this pathological process of GBM, finally result in exacerbating the proliferation, invasion, and migration of GBM. On the other hand, histone deacetylase inhibitors, DNA methyltransferases inhibitors, and RNA interference could reverse the inflammatory landscapes and inhibit GBM growth and invasion. Here, we systematically review the inflammatory-associated epigenetic changes and regulations in the microenvironment of GBM, aiming to provide a comprehensive epigenetic profile underlying the recognition of inflammation in GBM.

CDC42EP3 promotes glioma progression via regulation of CCND1

Gliomas are the most common brain malignancies characterized by high degree of aggressiveness and high mortality. However, the underlying mechanism of glioma progression remains unclear. Here, we probed the role of CDC42EP3 (CDC42 effector protein 3) played in glioma development and its potential downstream mechanism. The expression of CDC42EP3 in tumor and normal brain tissues were examined through immunohistochemistry and we found the likelihood of CDC42EP3 overexpression was positively correlated with pathological grading. Patients with higher expression of CDC42EP3 were more likely to suffer from recurrence as well. Through constructing CDC42EP3-knockdown cell models, we discovered that silencing CDC42EP3 significantly restricted cell proliferation and migration but facilitated cell apoptosis in vitro. Inhibition on tumor growth mediated by CDC42EP3 depletion was further verified in vivo. Regarding downstream target of CDC42EP3, we found that it may positively regulate the expression of CCND1 through c-Myc-mediated transcription. Furthermore, our findings affirmed that effects of CDC42EP3 overexpression on cell proliferation, migration and apoptosis could be confined by depleting CCND1. In a word, this study reported the tumor-promoting role of CDC42EP3 in glioma progression which probably functioned through targeting CCND1.

Microbiomics in Collusion with the Nervous System in Carcinogenesis: Diagnosis, Pathogenesis and Treatment

The influence of the naturally occurring population of microbes on various human diseases has been a topic of much recent interest. Not surprisingly, continuously growing attention is devoted to the existence of a gut brain axis, where the microbiota present in the gut can affect the nervous system through the release of metabolites, stimulation of the immune system, changing the permeability of the blood–brain barrier or activating the vagus nerves. Many of the methods that stimulate the nervous system can also lead to the development of cancer by manipulating pathways associated with the hallmarks of cancer. Moreover, neurogenesis or the creation of new nervous tissue, is associated with the development and progression of cancer in a similar manner as the blood and lymphatic systems. Finally, microbes can secrete neurotransmitters, which can stimulate cancer growth and development. In this review we discuss the latest evidence that support the importance of microbiota and peripheral nerves in cancer development and dissemination.

Macrophage migration inhibitory factor (MIF) inhibitor 4-IPP downregulates stemness phenotype and mesenchymal trans-differentiation after irradiation in glioblastoma multiforme

Radiation therapy is among the most essential treatment methods for glioblastoma multiforme (GBM). Radio-resistance and cancer stem cell properties can cause therapeutic resistance, cancer heterogeneity, and poor prognoses in association with GBM. Furthermore, the GBM subtype transition from proneural to the most malignant mesenchymal subtype after radiation therapy also accounts for high resistance to conventional treatments. Here, we demonstrate that the inhibition of macrophage migration inhibitory factor (MIF) and D-dopachrome tautomerase (DDT) by 4-iodo-6-phenylpyrimidine (4-IPP), a dual inhibitor targeting MIF and DDT, downregulates stemness phenotype, intracellular signaling cascades, mesenchymal trans-differentiation, and induces apoptosis in proneural glioma stem cells (GSCs). In an analysis of The Cancer Genome Atlas, high MIF and DDT expression were associated with poor prognosis. GSC growth was effectively inhibited by 4-IPP in a time- and dose-dependent manner, and 4-IPP combined with radiation therapy led to significantly reduced proliferation compared with radiation therapy alone. The expression of stemness factors, such as Olig2 and SOX2, and the expression of pAKT, indicating PI3K signaling pathway activation, were decreased in association with both 4-IPP monotherapy and combination treatment. The expression of mesenchymal markers, TGM2 and NF-κB, and expression of pERK (indicating MAPK signaling pathway activation) increased in association with radiation therapy alone but not with 4-IPP monotherapy and combination therapy. In addition, the combination of 4-IPP and radiation therapy significantly induced apoptosis compared to the monotherapy of 4-IPP or radiation. In vivo results demonstrated a significant tumor-suppressing effect of 4-IPP when combined with radiation therapy. Collectively, our results showed that the targeted inhibition of MIF and DDT has the potential to strengthen current clinical strategies by enhancing the anticancer effects of radiation therapy.

Role of Inflammatory Mediators, Macrophages, and Neutrophils in Glioma Maintenance and Progression: Mechanistic Understanding and Potential Therapeutic Applications

Simple Summary

The tumor microenvironment is a complex network comprised of neoplastic and a variety of immune cells, proteins, and inflammatory mediators. Previous studies have shown that during cancer progression, diverse inflammatory molecules, either directly or indirectly via recruiting immune cells, support the process of carcinogenesis. The present review focuses on the mechanistic understanding of the oncogenic role of these inflammatory mediators and immune cells, particularly tumor-associated macrophages (TAMs) and tumor-associated neutrophils (TANs) in glioma maintenance and progression. Moreover, the potential therapeutic benefits of targeting inflammatory mediators, immune cells, and associated signaling pathways in glioma genesis have also been discussed.

Abstract

Gliomas are the most common, highly malignant, and deadliest forms of brain tumors. These intra-cranial solid tumors are comprised of both cancerous and non-cancerous cells, which contribute to tumor development, progression, and resistance to the therapeutic regimen. A variety of soluble inflammatory mediators (e.g., cytokines, chemokines, and chemotactic factors) are secreted by these cells, which help in creating an inflammatory microenvironment and contribute to the various stages of cancer development, maintenance, and progression. The major tumor infiltrating immune cells of the tumor microenvironment include TAMs and TANs, which are either recruited peripherally or present as brain-resident macrophages (microglia) and support stroma for cancer cell expansion and invasion. These cells are highly plastic in nature and can be polarized into different phenotypes depending upon different types of stimuli. During neuroinflammation, glioma cells interact with TAMs and TANs, facilitating tumor cell proliferation, survival, and migration. Targeting inflammatory mediators along with the reprogramming of TAMs and TANs could be of great importance in glioma treatment and may delay disease progression. In addition, an inhibition of the key signaling pathways such as NF-κB, JAK/STAT, MAPK, PI3K/Akt/mTOR, and TLRs, which are activated during neuroinflammation and have an oncogenic role in glioblastoma (GBM), can exert more pronounced anti-glioma effects.

Csnk1a1 inhibition modulates the inflammatory secretome and enhances response to radiotherapy in glioma

Glioblastoma multiforme (GBM), a fatal brain tumour with no available targeted therapies, has a poor prognosis. At present, radiotherapy is one of the main methods to treat glioma, but it leads to an obvious increase in inflammatory factors in the tumour microenvironment, especially IL-6 and CXCL1, which plays a role in tumour to resistance radiotherapy and tumorigenesis. Casein kinase 1 alpha 1 (CK1α) (encoded on chromosome 5q by Csnk1a1) is considered an attractive target for Tp53 wild-type acute myeloid leukaemia (AML) treatment. In this study, we evaluated the anti-tumour effect of Csnk1a1 suppression in GBM cells in vitro and in vivo. We found that down-regulation of Csnk1a1 or inhibition by D4476, a Csnk1a1 inhibitor, reduced GBM cell proliferation efficiently in both Tp53 wild-type and Tp53-mutant GBM cells. On the contrary, overexpression of Csnk1a1 promoted cell proliferation and colony formation. Csnk1a1 inhibition improved the sensitivity to radiotherapy. Furthermore, down-regulation of Csnk1a1 reduced the production and secretion of pro-inflammatory factors. In the preclinical GBM model, treatment with D4476 significantly inhibited the increase in pro-inflammatory factors caused by radiotherapy and improved radiotherapy sensitivity, thus inhibiting tumour growth and prolonging animal survival time. These results suggest targeting Csnk1a1 exert an anti-tumour role as an inhibitor of inflammatory factors, providing a new strategy for the treatment of glioma.

RelB and Neuroinflammation

Neuroinflammation within the central nervous system involves multiple cell types that coordinate their responses by secreting and responding to a plethora of inflammatory mediators. These factors activate multiple signaling cascades to orchestrate initial inflammatory response and subsequent resolution. Activation of NF-κB pathways in several cell types is critical during neuroinflammation. In contrast to the well-studied role of p65 NF-κB during neuroinflammation, the mechanisms of RelB activation in specific cell types and its roles during neuroinflammatory response are less understood. In this review, we summarize the mechanisms of RelB activation in specific cell types of the CNS and the specialized effects this transcription factor exerts during neuroinflammation.

Therapeutic Potential of Selenium in Glioblastoma

Little progress has been made in the long-term management of malignant brain tumors, leaving patients with glioblastoma, unfortunately, with a fatal prognosis. Glioblastoma remains the most aggressive primary brain cancer in adults. Similar to other cancers, glioblastoma undergoes a cellular metabolic reprogramming to form an oxidative tumor microenvironment, thereby fostering proliferation, angiogenesis and tumor cell survival. Latest investigations revealed that micronutrients, such as selenium, may have positive effects in glioblastoma treatment, providing promising chances regarding the current limitations in surgical treatment and radiochemotherapy outcomes. Selenium is an essential micronutrient with anti-oxidative and anti-cancer properties. There is additional evidence of Se deficiency in patients suffering from brain malignancies, which increases its importance as a therapeutic option for glioblastoma therapy. It is well known that selenium, through selenoproteins, modulates metabolic pathways and regulates redox homeostasis. Therefore, selenium impacts on the interaction in the tumor microenvironment between tumor cells, tumor-associated cells and immune cells. In this review we take a closer look at the current knowledge about the potential of selenium on glioblastoma, by focusing on brain edema, glioma-related angiogenesis, and cells in tumor microenvironment such as glioma-associated microglia/macrophages.

Metabolic regulation on the immune environment of glioma through gut microbiota

The gut-brain axis has paved our way in understanding varieties of disease. The gut microbiota especially the bacterial population plays critical roles in immune system development and function. Glioma comprises 80 percent of malignant brain cancer and glioblastoma (GBM) is the most malignant kind. GBM has a reputation for its suppressive immune environment and poor patient prognosis. Moreover, altered metabolites from gut microbiota affect both systemic immune and central nervous system (CNS) immunity. Here we will focus on the crosstalk between gut microbiota and GBM, and further explore how this communication contributes to glioma initiation and development. Finally, we highlight the latest insights on the metabolic regulation of immunity through gut microbiota, which provides a promising therapeutic strategy for GBM.

Identification of a mesenchymal-related signature associated with clinical prognosis in glioma

Malignant glioma with a mesenchymal (MES) signature is characterized by shorter survival time due to aggressive dissemination and resistance to chemoradiotherapy. Here, this study used the TCGA database as the training set and the CGGA database as the testing set. Consensus clustering was performed on the two data sets, and it was found that two groups had distinguished prognostic and molecular features. Cox analysis and Lasso regression analysis were used to construct MES signature-based risk score model of glioma. Our results show that MES signature-based risk score model can be used to assess the prognosis of glioma. Three methods (ROC curve analyses, univariate Cox regression analysis, multivariate Cox regression analysis) were used to investigate the prognostic role of texture parameters. The result showed that the MES-related gene signature was proved to be an independent prognostic factor for glioma. Furthermore, functional analysis of the gene related to the risk signature showed that the genes sets were closely related to the malignant process of tumors. Finally, FCGR2A and EHD2 were selected for functional verification. Silencing these two genes inhibited the proliferation, migration and invasion of gliomas and reduced the expression of mesenchymal marker genes. Collectively, MES-related risk signature seems to provide a novel target for predicting the prognosis and treatment of glioma.

Perspective of mesenchymal transformation in glioblastoma

Despite aggressive multimodal treatment, glioblastoma (GBM), a grade IV primary brain tumor, still portends a poor prognosis with a median overall survival of 12–16 months. The complexity of GBM treatment mainly lies in the inter- and intra-tumoral heterogeneity, which largely contributes to the treatment-refractory and recurrent nature of GBM. By paving the road towards the development of personalized medicine for GBM patients, the cancer genome atlas classification scheme of GBM into distinct transcriptional subtypes has been considered an invaluable approach to overcoming this heterogeneity. Among the identified transcriptional subtypes, the mesenchymal subtype has been found associated with more aggressive, invasive, angiogenic, hypoxic, necrotic, inflammatory, and multitherapy-resistant features than other transcriptional subtypes. Accordingly, mesenchymal GBM patients were found to exhibit worse prognosis than other subtypes when patients with high transcriptional heterogeneity were excluded. Furthermore, identification of the master mesenchymal regulators and their downstream signaling pathways has not only increased our understanding of the complex regulatory transcriptional networks of mesenchymal GBM, but also has generated a list of potent inhibitors for clinical trials. Importantly, the mesenchymal transition of GBM has been found to be tightly associated with treatment-induced phenotypic changes in recurrence. Together, these findings indicate that elucidating the governing and plastic transcriptomic natures of mesenchymal GBM is critical in order to develop novel and selective therapeutic strategies that can improve both patient care and clinical outcomes. Thus, the focus of our review will be on the recent advances in the understanding of the transcriptome of mesenchymal GBM and discuss microenvironmental, metabolic, and treatment-related factors as critical components through which the mesenchymal signature may be acquired. We also take into consideration the transcriptomic plasticity of GBM to discuss the future perspectives in employing selective therapeutic strategies against mesenchymal GBM.

MPPED2 is downregulated in glioblastoma, and its restoration inhibits proliferation and increases the sensitivity to temozolomide of glioblastoma cells

Glioblastoma (GBM) is the most aggressive and lethal neoplasia of the central nervous system in adults. Based on the molecular signature genes, GBM has been classified in proneural, neural, mesenchymal and classical subtypes. The Metallophosphoesterase-domain-containing protein 2 (MPPED2) gene encodes a metallophosphodiesterase protein highly conserved throughout the evolution. MPPED2 downregulation, likely due to its promoter hypermethylation, has been found in several malignant neoplasias and correlated with a poor prognosis. In this study, we aimed to investigate the expression and the functional role of MPPED2 in GBM. TCGA and Gravendeel databases were employed to explore the MPPED2 expression levels in this type of tumor. We have found that MPPED2 expression is downregulated in GBM patients, showing a positive correlation with survival. Moreover, TCGA and Gravendeel data also revealed that MPPED2 expression negatively correlates with the most aggressive mesenchymal subtype. Additionally, the restoration of MPPED2 expression in U251 and GLI36 GBM cell lines decreases cell growth, migration and enhanced the sensitivity to the temozolomide, inducing apoptotic cell death, of GBM cells. These findings suggest that the restoration of MPPED2 function can be taken into consideration for an innovative GBM therapy.

miR-504 modulates the stemness and mesenchymal transition of glioma stem cells and their interaction with microglia via delivery by extracellular vesicles

Glioblastoma (GBM) is a highly aggressive tumor with poor prognosis. A small subpopulation of glioma stem cells (GSCs) has been implicated in radiation resistance and tumor recurrence. In this study we analyzed the expression of miRNAs associated with the functions of GSCs using miRNA microarray analysis of these cells compared with human neural stem cells. These analyses identified gene clusters associated with glioma cell invasiveness, axonal guidance, and TGF-β signaling. miR-504 was significantly downregulated in GSCs compared with NSCs, its expression was lower in GBM compared with normal brain specimens and further decreased in the mesenchymal glioma subtype. Overexpression of miR-504 in GSCs inhibited their self-renewal, migration and the expression of mesenchymal markers. The inhibitory effect of miR-504 was mediated by targeting Grb10 expression which acts as an oncogene in GSCs and GBM. Overexpression of exogenous miR-504 resulted also in its delivery to cocultured microglia by GSC-secreted extracellular vesicles (EVs) and in the abrogation of the GSC-induced polarization of microglia to M2 subtype. Finally, miR-504 overexpression prolonged the survival of mice harboring GSC-derived xenografts and decreased tumor growth. In summary, we identified miRNAs and potential target networks that play a role in the stemness and mesenchymal transition of GSCs and the miR-504/Grb10 pathway as an important regulator of this process. Overexpression of miR-504 exerted antitumor effects in GSCs as well as bystander effects on the polarization of microglia via delivery by EVs.

Biogenic silver/silver chloride nanoparticles inhibit human glioblastoma stem cells growth in vitro and Ehrlich ascites carcinoma cell growth in vivo

The importance of biogenic silver/silver chloride nanoparticles has become increasing day by day. In the present study, silver/silver chloride nanoparticles (Ag/AgCl‐NPs) were synthesized from Kaempferia rotunda tuberous rhizome extract to evaluate the antiproliferative activity against human glioblastoma stem cells (GSCs) in vitro and Ehrlich ascites carcinoma (EAC) cells in vivo in mice. Synthesis of nanoparticles was confirmed by colour change and UV‐visible spectrum and characterized by TEM, XRD, TGA, AFM and FTIR. K rotunda and recently synthesized Zizyphus mauritiana fruit extract‐mediated Ag/AgCl‐NPs inhibited 77.2% and 71% of GSCs growth at 32 µg/mL concentration with the IC₅₀ values of 6.8 and 10.4 µg/mL, respectively. Cell morphological studies and caspase‐3 immunofluorescence assay revealed that both biogenic nanoparticles induced apoptosis in GSCs. Expression levels of several genes were checked by real‐time PCR after treatment with K rotunda tuberous rhizome‐mediated Ag/AgCl‐NPs. PARP, EGFR, NOTCH2 and STAT3 gene expression were decreased with the increase of NFκB, TLR9, IL1, TNFα, IKK and p21 gene that would be the cause of induction of apoptosis in GSCs. The cell cycle arrest at G₂/M phase was confirmed by flow cytometric assay. Both nanoparticles were injected intraperitoneally to rapidly growing EAC cells for 5 consecutive days. Approximately, 32.3% and 55% EAC cells growth were inhibited by K rotunda tuberous rhizome‐mediated Ag/AgCl‐NPs at 6 and 12 mg/kg/day doses, respectively while only 20% cell growth inhibition was monitored at 12 mg/kg/day dose of Z mauritiana‐mediated Ag/AgCl‐NPs. From the above results, it can be concluded that presently synthesized nanoparticles would be a potent anticancer agent.

Heterogeneity Matters: Different Regions of Glioblastoma Are Characterized by Distinctive Tumor-Supporting Pathways

Simple Summary

5-ALA Fluorescence Guided Surgery aims at extending the boundaries of glioblastoma (GBM) resection. It is based on the use of a fluorescent dye, 5-aminolevulinic acid (5-ALA). Depending on the fluorescence levels, it is possible to distinguish the core of the tumor, the infiltrating borders and the healthy tissue. Since GBM progression is supported by tumor cells and their interaction with the surrounding microenvironment, we hypothesized that 5-ALA intensity could identify microenvironments with different tumor supporting properties. Taking advantage of glioma-associated stem cells; a human in vitro model of the glioma microenvironment, we demonstrate that all regions of the tumor support the tumor growth, but through different pathways. This study highlights the importance of understanding the TME to obtain key information on GBM biology and develop new therapeutic approaches.

Abstract

The glioblastoma microenvironment plays a substantial role in glioma biology. However, few studies have investigated its spatial heterogeneity. Exploiting 5-ALA Fluorescence Guided Surgery (FGS), we were able to distinguish between the tumor core (ALA+), infiltrating area (ALA-PALE) and healthy tissue (ALA−) of the glioblastoma, based on the level of accumulated fluorescence. The aim of this study was to investigate the properties of the microenvironments associated with these regions. For this purpose, we isolated glioma-associated stem cells (GASC), resident in the glioma microenvironment, from ALA+, ALA-PALE and ALA− samples and compared them in terms of growth kinetic, phenotype and for the expression of 84 genes associated with cancer inflammation and immunity. Differentially expressed genes were correlated with transcriptomic datasets from TCGA/GTEX. Our results show that GASC derived from the three distinct regions, despite a similar phenotype, were characterized by different transcriptomic profiles. Moreover, we identified a GASC-based genetic signature predictive of overall survival and disease-free survival. This signature, highly expressed in ALA+ GASC, was also well represented in ALA PALE GASC. 5-ALA FGS allowed to underline the heterogeneity of the glioma microenvironments. Deepening knowledge of these differences can contribute to develop new adjuvant therapies targeting the crosstalk between tumor and its supporting microenvironment.

Critical role of HOX transcript antisense intergenic RNA (HOTAIR) in gliomas

Despite extensive research, gliomas are associated with high morbidity and mortality, mainly attributed to the rapid growth rate, excessive invasiveness, and molecular heterogeneity, as well as regenerative potential of cancer stem cells. Therefore, elucidation of the underlying molecular mechanisms and the identification of potential molecular diagnostic and prognostic biomarkers are of paramount importance. HOX transcript antisense intergenic RNA (HOTAIR) is a well-studied long noncoding RNA, playing an emerging role in tumorigenesis of several human cancers. A growing amount of preclinical and clinical evidence highlights the pro-oncogenic role of HOTAIR in gliomas, mainly attributed to the enhancement of proliferation and migration, as well as inhibition of apoptosis. In vitro and in vivo studies demonstrate that HOTAIR modulates the activity of specific transcription factors, such as MXI1, E2F1, ATF5, and ASCL1, and regulates the expression of cell cycle-associated genes along with related signaling pathways, like the Wnt/β-catenin axis. Moreover, it can interact with specific miRNAs, including miR-326, miR-141, miR-148b-3p, miR-15b, and miR-126-5p. Of importance, HOTAIR has been demonstrated to enhance angiogenesis and affect the permeability of the blood-tumor barrier, thus modulating the efficacy of chemotherapeutic agents. Herein, we provide evidence on the functional role of HOTAIR in gliomas and discuss the benefits of its targeting as a novel approach toward glioma treatment.

Downregulation of the CCL2/CCR2 and CXCL10/CXCR3 axes contributes to antitumor effects in a mouse model of malignant glioma

Glioblastoma multiforme involves glioma stem cells (GSCs) that are resistant to various therapeutic approaches. Here, we studied the importance of paracrine signaling in the glioma microenvironment by focusing on the celecoxib-mediated role of chemokines C–C motif ligand 2 (CCL2), C-X-C ligand 10 (CXCL10), and their receptors, CCR2 and CXCR3, in GSCs and a GSC-bearing malignant glioma model. C57BL/6 mice were injected with orthotopic GSCs intracranially and divided into groups administered either 10 or 30 mg/kg celecoxib, or saline to examine the antitumor effects associated with chemokine expression. In GSCs, we analyzed cell viability and expression of chemokines and their receptors in the presence/absence of celecoxib. In the malignant glioma model, celecoxib exhibited antitumor effects in a dose dependent manner and decreased protein and mRNA levels of Ccl2 and CxcL10 and Cxcr3 but not of Ccr2. CCL2 and CXCL10 co-localized with Nestin⁺ stem cells, CD16⁺ or CD163⁺ macrophages and Iba-1⁺ microglia. In GSCs, celecoxib inhibited Ccl2 and Cxcr3 expression in a nuclear factor-kappa B-dependent manner but not Ccr2 and CxcL10. Moreover, Ccl2 silencing resulted in decreased GSC viability. These results suggest that celecoxib-mediated regulation of the CCL2/CCR2 and CXCL10/ CXCR3 axes may partially contribute to glioma-specific antitumor effects.

The Role of Shcbp1 in Signaling and Disease

Src homolog and collagen homolog (Shc) proteins have been identified as adapter proteins associated with cell surface receptors and have been shown to play important roles in signaling and disease. Shcbp1 acts as a Shc SH2-domain binding protein 1 and is involved in the regulation of signaling pathways, such as FGF, NF-κB, MAPK/ERK, PI3K/AKT, TGF-β1/Smad and β -catenin signaling. Shcbp1 participates in T cell development, the regulation of downstream signal transduction pathways, and cytokinesis during mitosis and meiosis. In addition, Shcbp1 has been demonstrated to correlate with Burkitt-like lymphoma, breast cancer, lung cancer, gliomas, synovial sarcoma, human hepatocellular carcinoma and other diseases. Shcbp1 may play an important role in tumorigenesis and progression. Accordingly, recent studies are reviewed herein to discuss and interpret the role of Shcbp1 in normal cell proliferation and differentiation, tumorigenesis and progression, as well as its interactions with proteins.

LINC01116 promotes tumor proliferation and neutrophil recruitment via DDX5-mediated regulation of IL-1β in glioma cell

Tumor-associated neutrophils (TANs) are important inflammatory infiltrating cells in the tumor microenvironment and are closely related to the development of human tumor. However, the underlying mechanism of TANs recruiting to glioma remains unknown. Herein, we identified that LINC01116 was significantly upregulated in glioma, and positively correlated with clinical malignancy and survival prognosis. LINC01116 regulated the progression of glioma in vitro and in vivo. RNA-seq analysis demonstrated that LINC01116 knockdown affected the expression of IL-1β, which promoted glioma proliferation and neutrophil recruitment. Furthermore, the co-culture of glioma cells and neutrophils showed that the accumulation of TANs promoted tumor proliferation via producing a host of cytokines. Mechanistically, LINC01116 activated IL-1β expression by recruiting the transcriptional regulator DDX5 to the IL-1β promoter. Our findings reveal that LINC01116 can promote glioma proliferation and neutrophil recruitment by regulating IL-1β, and may be served as a novel target for glioma therapy and prognosis.

DDX39B interacts with the pattern recognition receptor pathway to inhibit NF-κB and sensitize to alkylating chemotherapy

Background

Nuclear factor-κB (NF-κB) plays a prominent role in promoting inflammation and resistance to DNA damaging therapy. We searched for proteins that modulate the NF-κB response as a prerequisite to identifying novel factors that affect sensitivity to DNA damaging chemotherapy.

Results

Using streptavidin-agarose pull-down, we identified the DExD/H-box RNA helicase, DDX39B, as a factor that differentially interacts with κB DNA probes. Subsequently, using both RNA interference and CRISPR/Cas9 technology, we demonstrated that DDX39B inhibits NF-κB activity by a general mechanism involving inhibition of p65 phosphorylation. Mechanistically, DDX39B mediates this effect by interacting with the pattern recognition receptor (PRR), LGP2, a pathway that required the cellular response to cytoplasmic double-stranded RNA (dsRNA). From a functional standpoint, loss of DDX39B promoted resistance to alkylating chemotherapy in glioblastoma cells. Further examination of DDX39B demonstrated that its protein abundance was regulated by site-specific sumoylation that promoted its poly-ubiquitination and degradation. These post-translational modifications required the presence of the SUMO E3 ligase, PIASx-β. Finally, genome-wide analysis demonstrated that despite the link to the PRR system, DDX39B did not generally inhibit interferon-stimulated gene expression, but rather acted to attenuate expression of factors associated with the extracellular matrix, cellular migration, and angiogenesis.

Conclusions

These results identify DDX39B, a factor with known functions in mRNA splicing and nuclear export, as an RNA-binding protein that blocks a subset of the inflammatory response. While these findings identify a pathway by which DDX39B promotes sensitization to DNA damaging therapy, the data also reveal a mechanism by which this helicase may act to mitigate autoimmune disease.

The Bradykinin-BDKRB1 Axis Regulates Aquaporin 4 Gene Expression and Consequential Migration and Invasion of Malignant Glioblastoma Cells via a Ca2+-MEK1-ERK1/2-NF-κB Mechanism

Glioblastoma multiforme (GBM) is the most common form of brain tumor and is very aggressive. Rapid migration and invasion of glioblastoma cells are two typical features driving malignance of GBM. Bradykinin functionally prompts calcium influx via activation of bradykinin receptor B1/B2 (BDKRB1/2). In this study, we evaluated the roles of bradykinin in migration and invasion of glioblastoma cells and the possible mechanisms. Expressions of aquaporin 4 (AQP4) mRNA and protein were upregulated in human glioblastomas. Furthermore, exposure of human U87 MG glioblastoma cells to bradykinin specifically increased levels of BDKRB1. Successively, bradykinin stimulated influx of calcium, phosphorylation of MEK1 and extracellular signal-regulated kinase (ERK)1/2, translocation and transactivation of nuclear factor-kappaB (NF-κB), and expressions of AQP4 mRNA and protein. Concomitantly, migration and invasion of human glioblastoma cells were elevated by bradykinin. Knocking-down BDKRB1 concurrently decreased AQP4 mRNA expression and cell migration and invasion. The bradykinin-induced effects were further confirmed in murine GL261 glioblastoma cells. Therefore, bradykinin can induce AQP4 expression and subsequent migration and invasion through BDKRB1-mediated calcium influx and subsequent activation of a MEK1-ERK1/2-NF-κB pathway. The bradykinin-BDKRB1 axis and AQP4 could be precise targets for treating GBM patients.

Identification of Periostin as a Potential Biomarker in Gliomas by Database Mining

BACKGROUND

Bioinformatics analysis integrating microenvironmental factors and single cell analysis segregated the glioblastoma (GBM) subtype into 3 subtypes: proneural, classic, and mesenchymal. Mesenchymal GBM tends to have the worst survival but benefits from aggressive treatment protocols. Therefore, it is clinically meaningful to identify relevant biomarkers to distinguish the mesenchymal subtype. Moreover, in developing nations with limited resources, rigorous examinations are costly and inefficient for patient care.

METHODS

In this study, we analyzed The Cancer Genome Atlas (TCGA)-Glioblastoma and TCGA-Low-Grade Glioma RNA sequencing (RNAseq) cohorts and confirmed that the mesenchymal subtype was associated with the worst prognosis.

RESULTS

We identified periostin (POSTN) as a mesenchymal subtype biomarker with prognostic value across histologic grades and confirmed the reliability of POSTN by gene expression meta-analysis combining TCGA, Chinese Glioma Genome Atlas (CGGA) and REMBRANDT (Repository for Molecular Brain Neoplasia Data) GBM cohorts (hazard ratio, 1.71 [range, 1.47-2.07], n = 693) and LGG cohorts (hazard ratio, 2.55 [range, 1.61-4.05], n = 1226).

CONCLUSIONS

By using available online glioma databases, our study provided an insight into the expression of POSTN as an independent predictor for patients with glioma (GBM and LGG) and could be useful for diagnostic simplification to identify high-risk groups.

Mesenchymal transition and increased therapy resistance of glioblastoma cells is related to astrocyte reactivity

Grade IV astrocytoma/glioblastoma multiforme (GBM) is essentially incurable, partly due to its heterogenous nature, demonstrated even within the glioma-initiating cell (GIC) population. Increased therapy resistance of GICs is coupled to transition into a mesenchymal (MES) cell state. The GBM MES molecular signature displays a pronounced inflammatory character and its expression vary within and between tumors. Herein, we investigate how MES transition of GBM cells relates to inflammatory responses of normal astroglia. In response to CNS insults astrocytes enter a reactive cell state and participate in directing neuroinflammation and subsequent healing processes. We found that the MES signature show strong resemblance to gene programs induced in reactive astrocytes. Likewise, astrocyte reactivity gene signatures were enriched in therapy-resistant MES-like GIC clones. Variable expression of astrocyte reactivity related genes also largely defined intratumoral GBM cell heterogeneity at the single-cell level and strongly correlated with our previously defined therapy-resistance signature (based on linked molecular and functional characterization of GIC clones). In line with this, therapy-resistant MES-like GIC secreted immunoregulatory and tissue repair related proteins characteristic of astrocyte reactivity. Moreover, sensitive GIC clones could be made reactive through long-term exposure to the proinflammatory cytokine interleukin 1 beta (IL1β). IL1β induced a slow MES transition, increased therapy resistance, and a shift in DNA methylation profile towards that of resistant clones, which confirmed a slow reprogramming process. In summary, GICs enter through MES transition a reactive-astrocyte-like cell state, connected to therapy resistance. Thus, from a biological point of view, MES GICs would preferably be called 'reactive GICs'. The ability of GBM cells to mimic astroglial reactivity contextualizes the immunomodulatory and microenvironment reshaping abilities of GBM cells that generate a tumor-promoting milieu. This insight will be important to guide the development of future sensitizing therapies targeting treatment-resistant relapse-driving cell populations as well as enhancing the efficiency of immunotherapies in GBM. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

An Inflammatory Landscape for Preoperative Neurologic Deficits in Glioblastoma

Introduction: Patients with glioblastoma (GBM), one of the most aggressive forms of primary brain tumors, exhibit a wide range of neurologic signs, ranging from headaches to neurologic deficits and cognitive impairment, at first clinical presentation. While such variability is attributed to inter-individual differences in increased intracranial pressure, tumor infiltration, and vascular compromise, a direct association with disease stage, tumor size and location, edema, and necrotic cell death has yet to be established. The lack of specificity of neurologic symptoms often confounds the diagnosis of GBM. It also limits clinicians' ability to elect treatment regimens that not only prolong survival but also promote symptom management and high quality of life. Methods: To decipher the heterogeneous presentation of neurologic symptoms in GBM, we investigated differences in the molecular makeup of tumors from patients with and without preoperative neurologic deficits. We used the Ivy GAP (Ivy Glioblastoma Atlas Project) database to integrate RNA sequencing data from histologically defined GBM tumor compartments and neurologic examination records for 41 patients. We investigated the association of neurologic deficits with various tumor and patient attributes. We then performed differential gene expression and co-expression network analysis to identify a transcriptional signature specific to neurologic deficits in GBM. Using functional enrichment analysis, we finally provided a comprehensive and detailed characterization of involved pathways and gene interactions. Results: An exploratory investigation of the association of tumor and patient variables with the early development of neurologic deficits in GBM revealed a lack of robust and consistent clinicopathologic prognostic factors. We detected significant differences in the expression of 728 genes (FDR-adjusted p-value ≤ 0.05 and relative fold-change ≥ 1.5), unique to the cellular tumor (CT) anatomical compartment, between neurologic deficit groups. Upregulated differentially expressed genes in CT were enriched for mesenchymal subtype-predictive genes. Applying a systems approach, we then identified co-expressed gene sets that correlated with neurological deficit manifestation (FDR-adjusted p-value < 0.1). Collectively, these findings uncovered significantly enriched immune activation, oxidative stress response, and cytokine-mediated proinflammatory processes. Conclusion: Our study posits that inflammatory processes, as well as a mesenchymal tumor subtype, are implicated in the pathophysiology of preoperative neurologic deficits in GBM.

RelB acts as a molecular switch driving chronic inflammation in glioblastoma multiforme

Glioblastoma multiforme (GBM) is a primary brain tumor characterized by extensive necrosis and immunosuppressive inflammation. The mechanisms by which this inflammation develops and persists in GBM remain elusive. We identified two cytokines interleukin-1β (IL-1) and oncostatin M (OSM) that strongly negatively correlate with patient survival. We found that these cytokines activate RelB/p50 complexes by a canonical NF-κB pathway, which surprisingly drives expression of proinflammatory cytokines in GBM cells, but leads to their inhibition in non-transformed astrocytes. We discovered that one allele of the gene encoding deacetylase Sirtuin 1 (SIRT1), needed for repression of cytokine genes, is deleted in 80% of GBM tumors. Furthermore, RelB specifically interacts with a transcription factor Yin Yang 1 (YY1) in GBM cells and activates GBM-specific gene expression programs. As a result, GBM cells continuously secrete proinflammatory cytokines and factors attracting/activating glioma-associated microglia/macrophages and thus, promote a feedforward inflammatory loop.

The Gut-Brain Axis, Paving the Way to Brain Cancer

The gut-brain axis formed by blood and lymphatic vessels paves the way for microbiota to impact the brain. Bacterial populations in the gut are a good candidate for a nongenetic factor contributing substantively to brain tumor development and to the success of therapy. Specifically, suppression of the immune system and induction of inflammation by microbiota sustain proliferative signaling, limit cell death, and induce angiogenesis as well as invasiveness. In addition, altered microbial metabolites and their levels could stimulate cell proliferation. We propose here a novel gear model connecting these complex interdisciplinary fields. Our model may impact mechanistic studies of brain cancer and better treatment outcomes through precision oncology.

The Small Molecule Ephrin Receptor Inhibitor, GLPG1790, Reduces Renewal Capabilities of Cancer Stem Cells, Showing Anti-Tumour Efficacy on Preclinical Glioblastoma Models

Therapies against glioblastoma (GBM) show a high percentage of failure associated with the survival of glioma stem cells (GSCs) that repopulate treated tumours. Forced differentiation of GSCs is a promising new approach in cancer treatment. Erythropoietin-producing hepatocellular (Eph) receptors drive tumourigenicity and stemness in GBM. We tested GLPG1790, a first small molecule with inhibition activity versus inhibitor of various Eph receptor kinases, in preclinical GBM models using in vitro and in vivo assays. GLPG1790 rapidly and persistently inhibited Ephrin-A1-mediated phosphorylation of Tyr⁵⁸⁸ and Ser⁸⁹⁷, completely blocking EphA2 receptor signalling. Similarly, this compound blocks the ephrin B2-mediated EphA3 and EphB4 tyrosine phosphorylation. This resulted in anti-glioma effects. GLPG1790 down-modulated the expression of mesenchymal markers CD44, Sox2, nestin, octamer-binding transcription factor 3/4 (Oct3/4), Nanog, CD90, and CD105, and up-regulated that of glial fibrillary acidic protein (GFAP) and pro-neural/neuronal markers, βIII tubulin, and neurofilaments. GLPG1790 reduced tumour growth in vivo. These effects were larger compared to radiation therapy (RT; U251 and T98G xenografts) and smaller than those of temozolomide (TMZ; U251 and U87MG cell models). By contrast, GLPG1790 showed effects that were higher than Radiotherapy (RT) and similar to Temozolomide (TMZ) in orthotopic U87MG and CSCs-5 models in terms of disease-free survival (DFS) and overall survival (OS). Further experiments were necessary to study possible interactions with radio- and chemotherapy. GLPG1790 demonstrated anti-tumor effects regulating both the differentiative status of Glioma Initiating Cells (GICs) and the quality of tumor microenvironment, translating into efficacy in aggressive GBM mouse models. Significant common molecular targets to radio and chemo therapy supported the combination use of GLPG1790 in ameliorative antiglioma therapy.

DR7 encoded by human herpesvirus 6 promotes glioma development and progression

Purpose

We previously identified human herpesvirus 6 (HHV-6) infection in the pathogenesis of glioma. Direct repeat (DR)7, encoded by HHV-6, has been reported to possess malignant transforming activity and involved in Hodgkin's lymphoma carcinogenesis. Here, we aimed to determine the role of DR7 in the development and progression of glioma.

Patients and methods

A total of 27 glioma and 30 normal brain tissues were collected for detection of DR7. Glioma cell proliferation, colony formation, cell cycle, migration, invasion and angiogenesis were evaluated by Cell Counting Kit-8 (CCK-8), soft agar, propidium iodide staining, wound healing, Transwell and chick embryo chorioallantoic membrane assays, respectively. The potential mRNA targets of DR7 were determined using mRNA microarray and validated via Western blot and ELISA.

Results

DR7 could be detected in the 13 glioma tissues with a positive rate of 48.15%, but only the 5 normal brain tissues with a lower positive rate of 16.7%. The two strains of cells isolated from glioma tissues were also found to express DR7. CCK-8 and soft agar assays showed enhanced proliferation and colony formation in the cells expressing DR7 which might be in relation to acceleration of the G1/S phase transition by DR7. Further analyses showed that DR7 could promote glioma cell migration, invasion and angiogenesis. Expression profiles identified hundreds of differentially expressed mRNAs, among which P53, extracellular matrix (ECM) fibronectin, integrin receptor ITGβ5 and specific inhibitors of MMPs, tissue inhibitor of MMPs (TIMP)-2 and TIMP-4, were downregulated, whereas ECM-degrading proteinase MMP-3, proinflammatory cytokines IL-1β, IL-6 and IL-8, were upregulated by DR7, respectively.

Conclusion

We observed existence of DR7 in the glioma tissues, and overexpression of DR7 could promote glioma cell development and progression, which might be through creating an inflammatory microenvironment and enhancing degradation of ECM.

Hybrids by tumor-associated macrophages × glioblastoma cells entail nuclear reprogramming and glioblastoma invasion

Hybrid formation is a fundamental process in normal development and tissue homeostasis, while the presence and the biological role of hybrids between tumor-associated macrophages (TAMs) and glioblastoma (GBM) cells remain elusive. In this study, we observed that TAM-GBM cell hybrids existed in human GBM specimens as demonstrated by co-expression of glioma biomarkers (GFAP, IDH1^R132H and PDGFRA) and macrophage biomarkers (CD68 and CD14). Furthermore, TAM-GBM cell hybrids could also be found in C57BL/6 mice orthotopically inoculated with mouse GBM cells labeled with RFP and after co-culture of bone marrow-derived macrophages from GFP-expressed mice with RFP-labeled GBM cells. The hybrids underwent nuclear reprogramming with unique gene expression profile as compared to parental cells. Moreover, glioma invasion-associated genes were enriched in the hybrids that possessed higher invasiveness, and more hybrids in the invasive margin of GBM were observed as compared to GBM core area. Our data demonstrate the presence of TAM-GBM cell hybrids that enhance GBM invasion. With a better understanding of TAM-GBM cell hybrids, new therapeutic strategies targeting GBM will be developed to treat GBM patients.

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.

Interactions between tumor-associated macrophages and tumor cells in glioblastoma: unraveling promising targeted therapies

INTRODUCTION

Glioblastoma (GBM) is the deadliest primary malignant central nervous system (CNS) tumor with a median overall survival of 15 months despite a very intensive therapeutic regimen including maximal safe surgery, radiotherapy, and chemotherapy. Therefore, GBM treatment still raises major biological and therapeutic challenges. Areas covered: One of the hallmarks of the GBM is its tumor microenvironment including tumor-associated macrophages (TAM). TAM, accounting for approximately 30% of the GBM bulk cell population, may explain, at least in part, the immunosuppressive features of GBMs. The TAM are active and highly plastic immune cells and include two major ontogenetically different cell populations: (i) microglia and, (ii) monocytes-derived macrophages (MDM). TAM recruited to the tumor bulk can be reprogramed by GBM cells resulting in an ineffective anti-tumor response. Interestingly, interactions between TAM and GBM cells promote tumor oncogenesis (i.e. tumor cells proliferation and migration/invasion). This review aims to explore TAM targeting in GBM as a promising therapeutic option in the near future. Expert Commentary: A better understanding of TAM-GBM interactions and dynamics will certainly uncover new anti-GBM therapeutic avenues.

Overexpression of SHCBP1 promotes migration and invasion in gliomas by activating the NF-κB signaling pathway

Gliomas are common, aggressive central nervous system tumors with poor overall survival rates. Despite improvements in neurosurgery, chemotherapy, and radiotherapy, the outcomes of patients with malignant gliomas remain poor. Therefore, increased knowledge of the molecular mechanisms that regulate glioma progression is crucial to identify novel therapeutic targets. Here, we reported that SHCBP1, a member of Src homolog and collagen homolog (Shc) family, was significantly overexpressed in glioma tissues and glioma cell lines compared to the corresponding normal tissues and cells. Ectopic overexpression of SHCBP1 promoted glioma cell migration and invasion, whereas knockdown of endogenous SHCBP1 had the opposite effects. Importantly, we demonstrated that SHCBP1 promoted aggressiveness in gliomas by activating the NF-κB signaling pathway. Collectively, our study indicates that SHCBP1 plays a pivotal role to promote progression in gliomas and targeting the oncogenic effects of SHCBP1 may provide a clinical strategy to treat gliomas.

Neurofibromin knockdown in glioma cell lines is associated with changes in cytokine and chemokine secretion in vitro

The neurofibromin-1 tumor suppressor gene (NF1) is altered in approximately 20% of sporadic glioblastoma (GBM) cases. NF1 deficient GBM frequently shows a mesenchymal gene expression signature, suggesting a relationship between NF1 status and the tumor microenvironment. To identify changes in the production of secreted cytokines/chemokines in NF1 deficient glioma, we applied cytokine arrays to conditioned media from a panel of three GBM cell lines after siRNA-mediated NF1 knockdown. We identified increased secretion of platelet-derived growth factor AA (PDGF-AA), chitinase-3-like protein 1 (CHI3L1), interleukin-8 (IL-8), and endoglin (ENG) in different subsets of these cell lines. Secretion was associated with induction of the corresponding messenger RNA, suggesting a mechanism involving transcriptional upregulation. By contrast, in non-transformed immortalized normal human astrocytes, PDGF-AA secretion was increased upon NF1 knockdown, while secreted CHI3L1, ENG, and IL-8 were reduced or unchanged. Analysis of The Cancer Genome Atlas confirmed a relationship between glioma NF1 status and ENG and CHI3L1 in tumor samples. Overall, this study identifies candidate changes in secreted proteins from NF1 deficient glioma cells that could influence the tumor microenvironment, and suggests a direct link between NF1 loss and increased tumor cell production of CHI3L1 and endoglin, two factors implicated in mesenchymal identity in glioblastoma.

Role of the NFκB-signaling pathway in cancer

Cancer is a group of cells that malignantly grow and proliferate uncontrollably. At present, treatment modes for cancer mainly comprise surgery, chemotherapy, radiotherapy, molecularly targeted therapy, gene therapy, and immunotherapy. However, the curative effects of these treatments have been limited thus far by specific characteristics of tumors. Abnormal activation of signaling pathways is involved in tumor pathogenesis and plays critical roles in growth, progression, and relapse of cancers. Targeted therapies against effectors in oncogenic signaling have improved the outcomes of cancer patients. NFκB is an important signaling pathway involved in pathogenesis and treatment of cancers. Excessive activation of the NFκB-signaling pathway has been documented in various tumor tissues, and studies on this signaling pathway for targeted cancer therapy have become a hot topic. In this review, we update current understanding of the NFκB-signaling pathway in cancer.

NFAT1-regulated IL6 signalling contributes to aggressive phenotypes of glioma

Background

We previously demonstrated that the local immune status correlated with the glioma prognosis. Interleukin-6 (IL6) was identified as an important local immune-related risk marker related to unfavourable prognosis. In this study, we further investigated the role and regulation of IL6 signalling in glioma.

Methods

The expression and prognostic value of IL6 and the IL6 receptor (IL6R) were explored in The Cancer Genome Atlas (TCGA) and REMBRANDT databases and clinical samples. Functional effects of genetic knockdown and overexpression of IL6R or IL6 stimulation were examined in vitro and in tumours in vivo. The effects of the nuclear factor of activated T cells-1 (NFAT1) on the promoter activities of IL6R and IL6 were also examined.

Results

High IL6- and IL6R-expression were significantly associated with mesenchymal subtype and IDH-wildtype gliomas, and were predictors of poor survival. Knockdown of IL6R decreased cell proliferation, invasion and neurosphere formation in vitro, and inhibited tumorigenesis in vivo. IL6R overexpression or IL6 stimulation enhanced the invasion and growth of glioma cells. TCGA database searching revealed that IL6- and IL6R-expression were correlated with that of NFAT1. In glioma cells, NFAT1 enhanced the promoter activities of IL6R and IL6, and upregulated the expression of both IL6R and IL6.

Conclusion

NFAT1-regulated IL6 signalling contributes to aggressive phenotypes of gliomas, emphasizing the role of immunomodulatory factors in glioma malignant progression.

Electronic supplementary material

The online version of this article (10.1186/s12964-017-0210-1) contains supplementary material, which is available to authorized users.

Blocking interleukin-6 signaling inhibits cell viability/proliferation, glycolysis, and colony forming activity of human medulloblastoma cells

Elevated levels of the pro-inflammatory cytokine interleukin-6 (IL-6) have tumor-promoting activity and are associated with poor survival outcomes in many cancers. Additionally, the IL-6/GP130/STAT3 axis has been widely studied due to its pivotal role in tumor development and maintenance in a number of tissue types, including the cerebellum. However, the connection between IL-6 signaling and medulloblastoma progression is largely unexplored. In the present study, we observed that IL-6 induced medulloblastoma cell viability, cell proliferation and glycolysis. Furthermore, it also upregulated the expression of phosphorylated STAT3, indicating that the IL-6/GP130/STAT3 pathway plays a central role in medulloblastoma. The FDA-approved drug bazedoxifene, a blocker of the formation of the hexameric IL-6/IL-6R/GP130 complex, was re-purposed in this study to inhibit the IL-6/GP130/STAT3 signaling pathway. Bazedoxifene not only inhibited IL-6 mediated cell viability and cell proliferation, and increased phosphorylated STAT3 expression, but it also decreased cell glycolysis, demonstrating a certain level of therapeutic efficacy in vitro. Collectively, our findings offer new insight into the molecular mechanism underlying the biological aggressiveness of medulloblastoma, the roles of IL-6 in these processes and a possible efficacious adjuvant therapy for medulloblastoma.

Linc00152 promotes malignant progression of glioma stem cells by regulating miR-103a-3p/FEZF1/CDC25A pathway

BACKGROUND

Glioma is one of the most frequent intracranial malignant tumors. LncRNAs have been identified as new modulators in the origination and progression of glioma.

METHODS

Quantitative real-time PCR were conducted to evaluate the expression of linc00152 and miRNA-103a-3p in glioma tissues and cells. Western blot were used to determine the expression of FEZF1 and CDC25A in glioma tissues and cells. Stable knockdown of linc00152 or over-expression of miR-103a-3p in glioma stem cells (GSCs) were established to explore the function of linc00152 and miR-103a-3p in GSCs. Further, luciferase reports were used to investigate the correlation between linc00152 and miR-103a-3p. Cell Counting Kit-8, transwell assays, and flow cytometry were used to investigate the function of linc00152 and miR-103a-3p in GSC malignant biological behaviors. ChIP assays were employed to ascertain the correlations between FEZF1 and CDC25A.

RESULTS

Linc00152 was up-regulated in glioma tissues as well as in GSCs. Knockdown of linc00152 inhibited cell proliferation, migration and invasion, while promoted GSC apoptosis. Linc00152 regulated the malignant behavior of GSCs by binding to miR-103a-3p, which functions as a tumor suppressor. In addition, knockdown of linc00152 down-regulated forebrain embryonic zinc finger protein 1 (FEZF1), a direct target of miR-103a-3p which played an oncogenic role in GSCs. FEZF1 elevated promoter activities and up-regulated expression of the oncogenic gene cell division cycle 25A (CDC25A). CDC25A over-expression activated the PI3K/AKT pathways, which regulated the malignant behavior of GSCs.

CONCLUSIONS

Linc00152/miR-103a-3p/FEZF1/CDC25A axis plays a novel role in regulating the malignant behavior of GSCs, which may be a new potential therapeutic strategy for glioma therapy.