Downregulation of Wnt2 and beta-catenin by siRNA suppresses malignant glioma cell growth

PL-hMSC and CH-hMSC derived soluble factors inhibit proliferation but improve hGBM cell migration by activating TGF-β and inhibiting Wnt signaling

Glioblastoma multiforme (GBM) is one of the most common and aggressive brain tumors. GBM resists most chemotherapeutic agents, resulting in a high mortality rate in patients. Human mesenchymal stem cells (hMSCs), which are parts of the cancer stroma, have been shown to be involved in the development and progression of GBM. However, different sources of hMSCs might affect GBM cells differently. In the present study, we established hMSCs from placenta (PL-hMSC) and chorion (CH-hMSC) to study the effects of their released soluble factors on the proliferation, migration, invasion, gene expression, and survival of human GBM cells, U251. We found that the soluble factors derived from CH-hMSCs and PL-hMSCs suppressed the proliferation of U251 cells in a dose-dependent manner. In contrast, soluble factors derived from both hMSC sources increased U251 migration without affecting their invasive property. The soluble factors derived from these hMSCs decreased the expression levels of CyclinD1, E2Fs and MYC genes that promote GBM cell proliferation but increased the expression level of TWIST gene, which promotes EMT and GBM cell migration. The functional study suggests that both hMSCs might exert their effects, at least in part, by activating TGF-β and suppressing Wnt/β-catenin signaling in U251 cells. Our study provides a better understanding of the interaction between GBM cells and gestational tissue-derived hMSCs. This knowledge might be used to develop safer and more effective stem cell therapy that improves the survival and quality of life of patients with GBM by manipulating the interaction between hMSCs and GBM cells.

Glioma Stem Cells-Features for New Therapy Design

On a molecular level, glioma is very diverse and presents a whole spectrum of specific genetic and epigenetic alterations. The tumors are unfortunately resistant to available therapies and the survival rate is low. The explanation of significant intra- and inter-tumor heterogeneity and the infiltrative capability of gliomas, as well as its resistance to therapy, recurrence and aggressive behavior, lies in a small subset of tumor-initiating cells that behave like stem cells and are known as glioma cancer stem cells (GCSCs). They are responsible for tumor plasticity and are influenced by genetic drivers. Additionally, GCSCs also display greater migratory abilities. A great effort is under way in order to find ways to eliminate or neutralize GCSCs. Many different treatment strategies are currently being explored, including modulation of the tumor microenvironment, posttranscriptional regulation, epigenetic modulation and immunotherapy.

TMEM64 aggravates the malignant phenotype of glioma by activating the Wnt/β-catenin signaling pathway

Transmembrane protein 64 (TMEM64), a member of the family of transmembrane protein, is an α-helical membrane protein. Its precise role in various types of tumors, including glioma, is unclear. This study used immunohistochemical (IHC) staining, western blotting, and quantitative reverse transcription polymerase chain reaction (qRT-PCR) techniques to show that TMEM64 expression was significantly higher in glioma cells and tissues compared to normal cells and tissues, respectively. Additionally, a correlation between high TMEM64 expression and higher grade as well as a worse prognosis was found. TMEM64 enhanced cell proliferation and tumorigenicity while inhibiting glioma cell apoptosis in vitro and in vivo, according to loss- and gain-of-function studies. Mechanistically, it was discovered that TMEM64 increased the malignant phenotype of gliomas by accelerating the translocation of β-catenin from the cytoplasm to the nucleus, thereby activating the Wnt/β-catenin signaling pathway. Stimulation with the Wnt/β-catenin signaling pathway activator CHIR-99021 successfully reversed the malignant phenotype of glioma; however, these effects were inhibited upon TMEM64 silencing. Stimulation with the Wnt/β-catenin signaling pathway inhibitor XAV-939 successfully rescued the malignant phenotype of glioma, which was promoted upon TMEM64 overexpression. Our results provide that TMEM64 as a novel prognostic biomarker and a potential treatment target for glioma.

Human neural stem cells repress glioma cell progression in a paracrine manner by downregulating the Wnt/β-catenin signalling pathway

Neural stem cells (NSCs) play crucial roles in neurological disorders and tissue injury repair through exerting paracrine effects. However, the effects of NSC-derived factors on glioma progression remain unclear. This study aimed to evaluate the effects of human NSC-conditioned medium (NSC-CM) on the behaviour of glioma cells using an in vitro co-culture system. Cell counting kit-8 and 5-ethynyl-2'-deoxyuridine assays revealed that NSC-CM inhibited glioma cell proliferation and growth in a fetal bovine serum (FBS)-independent manner. In addition, our wound-healing assay demonstrated that NSC-CM repressed glioma cell migration, while results from transwell and 3D spheroid invasion assays indicated that NSC-CM also reduced the invasion capacity of glioma cells. Flow cytometry showed that NSC-CM prevented cell cycle progression from the G1 to S phase and promoted apoptosis. Western blotting was used to show that the expression of Wnt/β-catenin pathway-related proteins, including β-catenin, c-Myc, cyclin D1, CD44 and Met, was remarkably decreased in NSC-CM-treated glioma cells. Furthermore, the addition of a Wnt/β-catenin pathway activator, CHIR99021, significantly induced the expression of β-catenin and Met and increased the proliferative and invasive capabilities of control medium-treated glioma cells but not those of NSC-CM-treated glioma cells. The use of enzyme-linked immunosorbent assays (ELISA) revealed the secretion of some antitumour factors in human and rat NSCs, including interferon-α and dickkopf-1. Our data suggest that NSC-CM partially inhibits glioma cell progression by downregulating Wnt/β-catenin signalling. This study may serve as a basis for developing future antiglioma therapies based on NSC derivatives.

Wnt Signaling in Brain Tumors: A Challenging Therapeutic Target

The involvement of Wnt signaling in normal tissue homeostasis and disease has been widely demonstrated over the last 20 years. In particular, dysregulation of Wnt pathway components has been suggested as a relevant hallmark of several neoplastic malignancies, playing a role in cancer onset, progression, and response to treatments. In this review, we summarize the current knowledge on the instructions provided by Wnt signaling during organogenesis and, particularly, brain development. Moreover, we recapitulate the most relevant mechanisms through which aberrant Wnt pathway activation may impact on brain tumorigenesis and brain tumor aggressiveness, with a particular focus on the mutual interdependency existing between Wnt signaling components and the brain tumor microenvironment. Finally, the latest anti-cancer therapeutic approaches employing the specific targeting of Wnt signaling are extensively reviewed and discussed. In conclusion, here we provide evidence that Wnt signaling, due to its pleiotropic involvement in several brain tumor features, may represent a relevant target in this context, although additional efforts will be needed to: (i) demonstrate the real clinical impact of Wnt inhibition in these tumors; (ii) overcome some still unsolved concerns about the potential systemic effects of such approaches; (iii) achieve efficient brain penetration.

Modeling cartilage pathology in mucopolysaccharidosis VI using iPSCs reveals early dysregulation of chondrogenic and metabolic gene expression

Mucopolysaccharidosis type VI (MPS VI) is a metabolic disorder caused by disease-associated variants in the Arylsulfatase B (ARSB) gene, resulting in ARSB enzyme deficiency, lysosomal glycosaminoglycan accumulation, and cartilage and bone pathology. The molecular response to MPS VI that results in cartilage pathology in human patients is largely unknown. Here, we generated a disease model to study the early stages of cartilage pathology in MPS VI. We generated iPSCs from four patients and isogenic controls by inserting the ARSB cDNA in the AAVS1 safe harbor locus using CRISPR/Cas9. Using an optimized chondrogenic differentiation protocol, we found Periodic acid-Schiff positive inclusions in hiPSC-derived chondrogenic cells with MPS VI. Genome-wide mRNA expression analysis showed that hiPSC-derived chondrogenic cells with MPS VI downregulated expression of genes involved in TGF-β/BMP signalling, and upregulated expression of inhibitors of the Wnt/β-catenin signalling pathway. Expression of genes involved in apoptosis and growth was upregulated, while expression of genes involved in glycosaminoglycan metabolism was dysregulated in hiPSC-derived chondrogenic cells with MPS VI. These results suggest that human ARSB deficiency in MPS VI causes changes in the transcriptional program underlying the early stages of chondrogenic differentiation and metabolism.

Ror1 is expressed inducibly by Notch and hypoxia signaling and regulates stem cell-like property of glioblastoma cells

Ror1 plays a crucial role in cancer progression by regulating cell proliferation and migration. Ror1 is expressed abundantly in various types of cancer cells and cancer stem-like cells. However, the molecular mechanisms regulating expression of Ror1 in these cells remain largely unknown. Ror1 and its putative ligand Wnt5a are expressed highly in malignant gliomas, especially in glioblastomas, and the extents of Ror1 expression are correlated positively with poorer prognosis in patients with gliomas. We show that Ror1 expression can be upregulated in glioblastoma cells under spheroid culture, but not adherent culture conditions. Notch and hypoxia signaling pathways have been shown to be activated in spheroid-forming glioblastoma stem-like cells (GSCs), and Ror1 expression in glioblastoma cells is indeed suppressed by inhibiting either Notch or hypoxia signaling. Meanwhile, either forced expression of the Notch intracellular domain (NICD) in or hypoxic culture of glioblastoma cells result in enhanced expression of Ror1 in the cells. Consistently, we show that both NICD and hypoxia-inducible factor 1 alpha bind to upstream regions within the Ror1 gene more efficiently in GSCs under spheroid culture conditions. Furthermore, we provide evidence indicating that binding of Wnt5a to Ror1, upregulated by Notch and hypoxia signaling pathways in GSCs, might promote their spheroid-forming ability. Collectively, these findings indicate for the first time that Notch and hypoxia signaling pathways can elicit a Wnt5a-Ror1 axis through transcriptional activation of Ror1 in glioblastoma cells, thereby promoting their stem cell-like property.

Molecular Engines, Therapeutic Targets, and Challenges in Pediatric Brain Tumors: A Special Emphasis on Hydrogen Sulfide and RNA-Based Nano-Delivery

Pediatric primary brain tumors represent a real challenge in the oncology arena. Besides the psychosocial burden, brain tumors are considered one of the most difficult-to-treat malignancies due to their sophisticated cellular and molecular pathophysiology. Notwithstanding the advances in research and the substantial efforts to develop a suitable therapy, a full understanding of the molecular pathways involved in primary brain tumors is still demanded. On the other hand, the physiological nature of the blood-brain barrier (BBB) limits the efficiency of many available treatments, including molecular therapeutic approaches. Hydrogen Sulfide (H2S), as a member of the gasotransmitters family, and its synthesizing machinery have represented promising molecular targets for plentiful cancer types. However, its role in primary brain tumors, generally, and pediatric types, particularly, is barely investigated. In this review, the authors shed the light on the novel role of hydrogen sulfide (H2S) as a prominent player in pediatric brain tumor pathophysiology and its potential as a therapeutic avenue for brain tumors. In addition, the review also focuses on the challenges and opportunities of several molecular targeting approaches and proposes promising brain-delivery strategies for the sake of achieving better therapeutic results for brain tumor patients.

Research Progress on the Regulation Mechanism of Key Signal Pathways Affecting the Prognosis of Glioma

As is known to all, glioma, a global difficult problem, has a high malignant degree, high recurrence rate and poor prognosis. We analyzed and summarized signal pathway of the Hippo/YAP, PI3K/AKT/mTOR, miRNA, WNT/β-catenin, Notch, Hedgehog, TGF-β, TCS/mTORC1 signal pathway, JAK/STAT signal pathway, MAPK signaling pathway, the relationship between BBB and signal pathways and the mechanism of key enzymes in glioma. It is concluded that Yap1 inhibitor may become an effective target for the treatment of glioma in the near future through efforts of generation after generation. Inhibiting PI3K/Akt/mTOR, Shh, Wnt/β-Catenin, and HIF-1α can reduce the migration ability and drug resistance of tumor cells to improve the prognosis of glioma. The analysis shows that Notch1 and Sox2 have a positive feedback regulation mechanism, and Notch4 predicts the malignant degree of glioma. In this way, notch cannot only be treated for glioma stem cells in clinic, but also be used as an evaluation index to evaluate the prognosis, and provide an exploratory attempt for the direction of glioma treatment. MiRNA plays an important role in diagnosis, and in the treatment of glioma, VPS25, KCNQ1OT1, KB-1460A1.5, and CKAP4 are promising prognostic indicators and a potential therapeutic targets for glioma, meanwhile, Rheb is also a potent activator of Signaling cross-talk etc. It is believed that these studies will help us to have a deeper understanding of glioma, so that we will find new and better treatment schemes to gradually conquer the problem of glioma.

Research Progress on the Regulation Mechanism of Key Signal Pathways Affecting the Prognosis of Glioma

As is known to all, glioma, a global difficult problem, has a high malignant degree, high recurrence rate and poor prognosis. We analyzed and summarized signal pathway of the Hippo/YAP, PI3K/AKT/mTOR, miRNA, WNT/β-catenin, Notch, Hedgehog, TGF-β, TCS/mTORC1 signal pathway, JAK/STAT signal pathway, MAPK signaling pathway, the relationship between BBB and signal pathways and the mechanism of key enzymes in glioma. It is concluded that Yap1 inhibitor may become an effective target for the treatment of glioma in the near future through efforts of generation after generation. Inhibiting PI3K/Akt/mTOR, Shh, Wnt/β-Catenin, and HIF-1α can reduce the migration ability and drug resistance of tumor cells to improve the prognosis of glioma. The analysis shows that Notch1 and Sox2 have a positive feedback regulation mechanism, and Notch4 predicts the malignant degree of glioma. In this way, notch cannot only be treated for glioma stem cells in clinic, but also be used as an evaluation index to evaluate the prognosis, and provide an exploratory attempt for the direction of glioma treatment. MiRNA plays an important role in diagnosis, and in the treatment of glioma, VPS25, KCNQ1OT1, KB-1460A1.5, and CKAP4 are promising prognostic indicators and a potential therapeutic targets for glioma, meanwhile, Rheb is also a potent activator of Signaling cross-talk etc. It is believed that these studies will help us to have a deeper understanding of glioma, so that we will find new and better treatment schemes to gradually conquer the problem of glioma.

Roles of Non-coding RNAs and Angiogenesis in Glioblastoma

One of the significant hallmarks of cancer is angiogenesis. It has a crucial function in tumor development and metastasis. Thus, angiogenesis has become one of the most exciting targets for drug development in cancer treatment. Here we discuss the regulatory effects on angiogenesis in glioblastoma (GBM) of non-coding RNAs (ncRNAs), including long ncRNA (lncRNA), microRNA (miRNA), and circular RNA (circRNA). These ncRNAs may function in trans or cis forms and modify gene transcription by various mechanisms, including epigenetics. NcRNAs may also serve as crucial regulators of angiogenesis-inducing molecules. These molecules include, metalloproteinases, cytokines, several growth factors (platelet-derived growth factor, vascular endothelial growth factor, fibroblast growth factor, hypoxia-inducible factor-1, and epidermal growth factor), phosphoinositide 3-kinase, mitogen-activated protein kinase, and transforming growth factor signaling pathways.

Knockdown of long non-coding RNA SLC8A1-AS1 attenuates cell invasion and migration in glioma via suppression of Wnt/β-catenin signaling pathways

As the most common aggressive malignant tumor in the central nervous system, glioma is still an insurmountable disease in the neural system. The mechanism of carcinogenesis in glioma remains largely unclear. In the present study, we identified a dysregulated long non-coding RNA (lncRNA) solute carrier family 8 member A1 antisense RNA 1 (SLC8A1-AS1) associated with glioma based on The Cancer Genome Atlas (TCGA) data. A validation experiment was conducted to confirm a high expression level of lncRNA SLC8A1-AS1 in glioma tissues. Down-regulation of lncRNA SLC8A1-AS1 suppressed the proliferation, colony formation, migration, and invasion of glioma cells in vitro and in vivo. Moreover, lncRNA SLC8A1-AS1 silencing decreased the activity of the Wnt/β-catenin pathway and suppressed the epithelial to mesenchymal transition (EMT) in glioma cells. These findings collectively provide novel insights into the function and mechanism of lncRNA SLC8A1-AS1 in the pathogenesis of glioma and highlight its potential as a therapeutic target for glioma intervention.

AEG-1 silencing attenuates M2-polarization of glioma-associated microglia/macrophages and sensitizes glioma cells to temozolomide

Glioma is the most frequent primary malignancy in the brain; temozolomide (TMZ) is the first-line chemotherapeutic agent used to combat this tumor. We showed here that astrocyte elevated gene-1 (AEG-1) was overexpressed in glioma tissues and associated with a worse subtype and a poor prognosis. CCK-8 proliferation assays and clone formation experiments presented that AEG-1 knockdown sensitizes glioma cells to TMZ. The γH2AX foci formation assays indicated that AEG-1 silencing promotes TMZ-induced DNA damage in glioma cells. Glioma-associated microglia/macrophages (GAMs), the largest subpopulation infiltrating glioma, play important roles in the tumor microenvironment. Bioinformatics analyses and functional studies demonstrated that AEG-1 silencing decreased M2-polarization of HMC3 microglia and the secretion of tumor supportive cytokines IL-6 and TGF-β1. The expression of AEG-1 was positively associated with M2 markers in glioma tissues varified by IHC staining. Based on the results of Affymetrix microarray and GSEA analyses, Western blot and Co-Immunoprecipitation assays were conducted to show that AEG-1 activates Wnt/β-catenin signaling by directly interacting with GSK-3β. The co-localization of AEG-1 and GSK-3β in the cytoplasm of glioma cells was detected through immunofluorescence staining. This study raises the possibility that targeting AEG-1 might improve the efficiency of chemotherapy and reduce immunosuppressive M2 GAMs in glioma.

Zika virus E protein dysregulate mir-204/WNT2 signalling in human fetal neural stem cells

Zika Virus (ZIKV) belongs to the family of flaviviruses, and is neurotrophic. It has been known to cause severe congenital disabilities including microcephaly in neonates. The virus has a specific preference towards neural stem cells (NSCs). ZIKV impairs proliferation and differentiation of NSCs during in-utero brain development of the fetus. However, molecular pathways involved in ZIKV induced alteration in NSCs are yet to be explored. In our previous study, we have described that ZIKV E protein dysregulates microRNA circuitry in NSCs and also impairs their proliferative and differentiation abilities. WNT signalling was found to be the target of differentially expressed miRNAs as suggested by PANTHER PATHWAY analysis of differentially expressed miRNA targets. In our current follow-up study, we investigate that WNT2 is downregulated in response to ZIKV E protein in human fetal NSCs and WNT2 is the molecular target of microRNA miR-204-5p. We provide pieces of evidences that miR-204-5p/WNT2 axis is involved in ZIKV induced impairment in the proliferation and immature differentiation of neural stem cells.

The Renin-Angiotensin System in the Tumor Microenvironment of Glioblastoma

Simple Summary

Glioblastoma (GB) is the most aggressive brain cancer in humans. Patient survival outcomes have remained dismal despite intensive research over the past 50 years, with a median overall survival of only 14.6 months. We highlight the critical role of the renin–angiotensin system (RAS) on GB cancer stem cells and the tumor microenvironment which, in turn, influences cancer stem cells in driving tumorigenesis and treatment resistance. We present recent developments and underscore the need for further research into the GB tumor microenvironment. We discuss the novel therapeutic targeting of the RAS using existing commonly available medications and utilizing model systems to further this critical investigation.

Abstract

Glioblastoma (GB) is an aggressive primary brain tumor. Despite intensive research over the past 50 years, little advance has been made to improve the poor outcome, with an overall median survival of 14.6 months following standard treatment. Local recurrence is inevitable due to the quiescent cancer stem cells (CSCs) in GB that co-express stemness-associated markers and components of the renin–angiotensin system (RAS). The dynamic and heterogeneous tumor microenvironment (TME) plays a fundamental role in tumor development, progression, invasiveness, and therapy resistance. There is increasing evidence showing the critical role of the RAS in the TME influencing CSCs via its upstream and downstream pathways. Drugs that alter the hallmarks of cancer by modulating the RAS present a potential new therapeutic alternative or adjunct to conventional treatment of GB. Cerebral and GB organoids may offer a cost-effective method for evaluating the efficacy of RAS-modulating drugs on GB. We review the nexus between the GB TME, CSC niche, and the RAS, and propose re-purposed RAS-modulating drugs as a potential therapeutic alternative or adjunct to current standard therapy for GB.

Tumor Spheroids of an Aggressive Form of Central Neurocytoma Have Transit-Amplifying Progenitor Characteristics with Enhanced EGFR and Tumor Stem Cell Signaling

Central neurocytoma (CN) has been known as a benign neuronal tumor. In rare cases, CN undergoes malignant transformation to glioblastomas (GBM). Here we examined its cellular origin by characterizing differentiation potential and gene expression of CN-spheroids. First, we demonstrate that both CN tissue and cultured primary cells recapitulate the hierarchal cellular composition of subventricular zone (SVZ), which is comprised of neural stem cells (NSCs), transit amplifying progenitors (TAPs), and neuroblasts. We then derived spheroids from CN which displayed EGFR+/MASH+ TAP and BLBP+ radial glial cell (RGC) characteristic, and mitotic neurogenesis and gliogenesis by single spheroids were observed with cycling multipotential cells. CN-spheroids expressed increased levels of pluripotency and tumor stem cell genes such as KLF4 and TPD5L1, when compared to their differentiated cells and human NSCs. Importantly, Gene Set Enrichment Analysis showed that gene sets of GBM-Spheroids, EGFR Signaling, and Packaging of Telomere Ends are enriched in CN-spheroids in comparison with their differentiated cells. We speculate that CN tumor stem cells have TAP and RGC characteristics, and upregulation of EGFR signaling as well as downregulation of eph-ephrin signaling have critical roles in tumorigenesis of CN. And their ephemeral nature of TAPs destined to neuroblasts, might reflect benign nature of CN.

Expression profiles and prognostic significance of WNT family members in glioma via bioinformatic analysis

AIMS

The dysregulation and essential role of WNTs in glioma have been widely implicated. However, there is a paucity of literature on the expression status of all the 19 WNTs in glioma. Our study was aimed to evaluate the expression and prognostic values of the 19 WNTs in glioma.

METHODS

mRNA expression and clinical data were retrieved from the Cancer Genome Atlas (TCGA) database, Chinese Glioma Genome Atlas (CGGA), GTEx and ONCOMINE databases. The 50 frequent neighbor genes of WNT5A and WNT10B were shown with PPI network, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses.

RESULTS

We found that the mRNA expression of WNT5A was significantly higher in glioma; however, the WNT10B expression was significantly lower in glioma. Furthermore, the expression of WNT5A and WNT10B was associated with the clinicopathology of glioma. The survival analysis revealed that the higher expressions of WNT5A and WNT16 were associated poor overall survival (OS) in patients with glioma. Conversely, overexpression of WNT3, WNT5B, and WNT10B was associated with better OS. Finally, Go and KEGG analysis revealed WNT5A was associated with multiple signal translations, and crucial oncogenes (EGFR and MDM2) and 2 important tumor suppressors (PTEN and IKN4a/ARF) were found closely correlated with WNT5A in glioma.

CONCLUSION

Among 19WNTs, WNT5A can serve as a candidate to diagnose and therapy glioma, while WNT10B might be valuable for anti-glioma research. The presumed direction was provided to explore the relation of WNTs signal and multiple pathways in glioma.

Microglia in the Brain Tumor Microenvironment

Microglia are the brain resident phagocytes that act as the primary form of the immune defense in the central nervous system. These cells originate from primitive macrophages that arise from the yolk sac. Advances in imaging and single-cell RNA-seq technologies provided new insights into the complexity of microglia biology.Microglia play an essential role in the brain development and maintenance of brain homeostasis. They are also crucial in injury repair in the central nervous system. The tumor microenvironment is complex and includes neoplastic cells as well as varieties of host and infiltrating immune cells. Microglia are part of the glioma microenvironment and play a critical part in initiating and maintaining tumor growth and spread. Microglia can also act as effector cells in treatments against gliomas. In this chapter, we summarize the current knowledge of how and where microglia are generated. We also discuss their functions during brain development, injury repair, and homeostasis. Moreover, we discuss the role of microglia in the tumor microenvironment of gliomas and highlight their therapeutic implications.

Wnt/beta-catenin and PI3K/Akt/mTOR Signaling Pathways in Glioblastoma: Two Main Targets for Drug Design: A Review

Glioblastoma (GBM) is the most common and malignant astrocytic glioma, accounting for about 90% of all brain tumors with poor prognosis. Despite recent advances in understanding molecular mechanisms of oncogenesis and the improved neuroimaging technologies, surgery, and adjuvant treatments, the clinical prognosis of patients with GBM remains persistently unfavorable. The signaling pathways and the regulation of growth factors of glioblastoma cells are very abnormal. The various signaling pathways have been suggested to be involved in cellular proliferation, invasion, and glioma metastasis. The Wnt signaling pathway with its pleiotropic functions in neurogenesis and stem cell proliferation is implicated in various human cancers, including glioma. In addition, the PI3K/Akt/mTOR pathway is closely related to growth, metabolism, survival, angiogenesis, autophagy, and chemotherapy resistance of GBM. Understanding the mechanisms of GBM's invasion, represented by invasion and migration, is an important tool in designing effective therapeutic interventions. This review will investigate two main signaling pathways in GBM: PI3K/Akt/mTOR and Wnt/beta-catenin signaling pathways.

The role of MiRNA-21 in gliomas: Hope for a novel therapeutic intervention?

Gliomas are the most common primary brain tumors in adults. They are generally very resistant to treatment and are therefore associated with negative outcomes. MicroRNAs (miRNAs) are small, non-coding RNA molecules that affect many cellular processes by regulating gene expression and, post-transcriptionally, the translation of mRNAs. MiRNA-21 has been consistently shown to be upregulated in glioma and research has shown that it is involved in a wide variety of biological pathways, promoting tumor cell survival and invasiveness. Furthermore, it has been implicated in resistance to treatment, both against chemotherapy and radiotherapy. In this review, we gathered the existent data on miRNA-21 and gliomas, in terms of its expression levels, association with grade and prognosis, the pathways it involves and its targets in glioma, and finally how it leads to treatment resistance. Furthermore, we discuss how this knowledge could be applied in clinical practice in the years to come. To our knowledge, this is the first review to assess in extent and depth the role of miRNA-21 in gliomas.

Improving Radiation Response in Glioblastoma Using ECO/siRNA Nanoparticles Targeting DNA Damage Repair

Simple Summary

Glioblastoma (GBM) is the most common form of brain cancer and among the most lethal of human cancers. Radiation therapy is a mainstay in the standard of care for GBM, killing tumor cells by creating DNA damage. Inhibiting DNA damage repair (DDR) proteins enhances radiation therapy by not allowing tumor cells to repair the DNA damage caused by radiation. The aim of our study was to investigate whether the novel nanoparticle material, ECO, could be used to deliver small interfering RNA (siRNA) to GBM tumor cells and temporarily reduce the production of DDR proteins to improve radiation therapy outcomes. SiRNAs can be designed to target an innumerable number of genes and with the right delivery vehicle can be used in a variety of disease settings. Our work provides support for the use of the novel ECO material for delivery of siRNA in GBM.

Abstract

Radiation therapy is a mainstay in the standard of care for glioblastoma (GBM), thus inhibiting the DNA damage response (DDR) is a major strategy to improve radiation response and therapeutic outcomes. Small interfering RNA (siRNA) therapy holds immeasurable potential for the treatment of GBM, however delivery of the siRNA payload remains the largest obstacle for clinical implementation. Here we demonstrate the effectiveness of the novel nanomaterial, ECO (1-aminoethylimino[bis(N-oleoylcysteinylaminoethyl) propionamide]), to deliver siRNA targeting DDR proteins ataxia telangiectasia mutated and DNA-dependent protein kinase (DNApk-cs) for the radiosensitzation of GBM in vitro and in vivo. ECO nanoparticles (NPs) were shown to efficiently deliver siRNA and silence target protein expression in glioma (U251) and glioma stem cell lines (NSC11, GBMJ1). Importantly, ECO NPs displayed no cytotoxicity and minimal silencing of genes in normal astrocytes. Treatment with ECO/siRNA NPs and radiation resulted in the prolonged presence of γH2AX foci, indicators of DNA damage, and increased radiosensitivity in all tumor cell lines. In vivo, intratumoral injection of ECO/siDNApk-cs NPs with radiation resulted in a significant increase in survival compared with injection of NPs alone. These data suggest the ECO nanomaterial can effectively deliver siRNA to more selectively target and radiosensitize tumor cells to improve therapeutic outcomes in GBM.

Regulation of β-catenin by IGFBP2 and its cytoplasmic actions in glioma

PURPOSE

IGFBP2 is one of the highly expressed genes in glioblastoma (GBM). It has both IGF dependent and independent activities. IGF independent actions are mediated by the activation of integrin signalling through its RGD motif present at C-terminal domain. One of the actions of IGFBP2 is to regulate β-catenin by the inactivation of GSK3β, which preferentially accumulates in the cytoplasm. The mechanism of nuclear β-catenin regulation by IGFBP2 and role of cytoplasmic β-catenin is not clear. We aimed to understand the mechanism in GBM cell lines.

METHODS

The gene expression studies were performed by RT-PCR, western blot analysis; the knockdown of genes was performed by shRNA transfection; RNAIP and luciferase reporter assays were utilized to study the cytoplasmic regulation of genes by β-catenin; neurosphere assays were performed to study the stemness of cells.

RESULTS

IGFBP2 overexpression or treatment in GBM cells regulates β-catenin, TRIM33 (E3 ubiquitin ligase) and Oct4 genes. TRIM33 was induced by IGFBP2. β-catenin was found to accumulate predominantly in the cytoplasm and nuclear β-catenin was depleted by IGFBP2 induced TRIM33. IGFBP2 regulated cytoplasmic β-catenin binds to 3' UTR of Oct4 RNA. IGFBP2 was also able to induce stemness of glioma cells.

CONCLUSIONS

IGFBP2 induces TRIM33 which regulates the nuclear β-catenin protein. In addition, IGFBP2 stabilizes the cytoplasmic β-catenin which is involved in the regulation of Oct4 transcript and consequently induction of stemness of glioma cells.

A novel molecular link between HOXA9 and WNT6 in glioblastoma identifies a subgroup of patients with particular poor prognosis

Despite much effort to improve treatments, patients with malignant glioma still present a very poor prognosis that has not changed significantly in the last decades. In this context, it is crucial to better understand glioma pathogenesis to identify new molecular prognostic subgroups and therapeutic targets. WNT6 was recently identified as a new oncogenic molecule in glioblastoma (GBM), with prognostic value in patients, but the mechanisms underlying WNT6 aberrant expression in glioma are still unknown. WNT6 was overexpressed in a subset of gliomas independently of IDH mutations, 1p/19q codeletion status, and WNT6 gene copy number. Interestingly, WNT6 expression is associated with the DNA methylation levels of particular CpG regions at both the WNT6 promoter and the gene body in glioma patient samples. HOXA9, a transcription factor previously associated with poorer clinical outcome in GBM, was identified as a novel transcriptional regulator of WNT6, activating the WNT/β‐catenin pathway in vitro and in vivo. In various cohorts of glioma patients, mRNA levels of WNT6 and HOXA9 were significantly correlated, extending our in vitro and in vivo findings into the clinical setting. Interestingly, this novel molecular link between WNT6 and HOXA9 was not limited to glioma, as they were co‐expressed also in patients with other tumor types. Clinically, WNT6 was a prognostic biomarker of shorter survival in GBM, independently of HOXA9 expression. Concomitant high expression of both WNT6 and HOXA9 identified a subgroup of patients with particularly dismal survival. These findings describe novel WNT6 regulatory mechanisms in GBM, establishing particular DNA methylation patterns and HOXA9 as critical regulators of WNT6 expression in glioma. This HOXA9‐WNT6 molecular link supports WNT signaling in GBM cells and is a powerful prognostic biomarker, highlighting the clinical relevance of this axis in patients. Novel therapies targeting WNT6‐HOXA9 signaling may thus be useful for this deadly disease.

An update on Wnt signaling pathway in cancer

Wnt signaling involves many aspects of development, cell biology and physiology. Mutations in the Wnt gene can lead to abnormal embryonic development and cancer formation, including various aspects that affect proliferation, morphogenesis, and differentiation. The occurrence and development of tumors is a complex process involving multiple factors. The Wnt signaling pathway participates in this process as an anti-tumor target by activating multiple gene transcriptions. The emergence of Wnt pathway inhibitors and targeted drugs has opened up a new world of cancer treatment. This review focuses on the mechanism of action of the Wnt signaling pathway in different cancers. Secondly, we have organized and introduced the latest Wnt anti-tumor drugs.

The Plant-Derived Compound Resveratrol in Brain Cancer: A Review

Despite intensive research, malignant brain tumors are among the most difficult to treat due to high resistance to conventional therapeutic approaches. High-grade malignant gliomas, including glioblastoma and anaplastic astrocytoma, are among the most devastating and rapidly growing cancers. Despite the ability of standard treatment agents to achieve therapeutic concentrations in the brain, malignant gliomas are often resistant to alkylating agents. Resveratrol is a plant polyphenol occurring in nuts, berries, grapes, and red wine. Resveratrol crosses the blood‒brain barrier and may influence the central nervous system. Moreover, it influences the enzyme isocitrate dehydrogenase and, more importantly, the resistance to standard treatment via various mechanisms, such as O6-methylguanine methyltransferase. This review summarizes the anticancer effects of resveratrol in various types of brain cancer. Several in vitro and in vivo studies have presented promising results; however, further clinical research is necessary to prove the therapeutic efficacy of resveratrol in brain cancer treatment.

Aberrant expression of long non-coding RNAs (lncRNAs) is involved in brain glioma development

INTRODUCTION

Aberrant expression of long non-coding RNAs (lncRNAs) has been implicated in various diseases, including cancer. However, little is known about lncRNAs in human brain gliomas.

MATERIAL AND METHODS

We examined lncRNA profiles from three glioma specimens using lncRNA expression profiling microarrays. Quantitative real-time RT-PCR was used to analyze the differential expression of raw intensities of lncRNA expression in glioma and peritumoral tissues.

RESULTS

We found 4858 lncRNAs to be differentially expressed between tumor tissue and peritumoral tissue. Of these, 2845 lncRNAs were up-regulated (fold change > 3.0) and 2013 were down-regulated (fold change < 1/3). A total of 4084 messenger RNAs were also differentially expressed, including 2280 up-regulated transcripts (fold change > 3.0) and 1804 that were down-regulated (fold change < 1/3). Consistent with the microarray data, qPCR confirmed differential expression of these 6 lncRNAs (ak125809, ak098473, uc002ehu.1, bc043564, NR_027322, and uc003qmb.2) between tumor and peritumoral tissue. We next established co-expression networks of differentially expressed lncRNAs and mRNAs. Many mRNAs, such as LOC729991, NUDCD1, SHC3, PDGFA, and MDM2, and lncRNAs, such as ENST00000425922, ENST00000455568, uc002ukz.1, ENST00000502715, and NR_027873, have been shown to play important roles in glioma development. Consistent with this, pathway analysis revealed that "GLIOMA" (KEGG Pathway ID: hsa05214) was significantly enriched in tumor tissue.

CONCLUSIONS

Our data suggest that altered expression of lncRNAs may be a critical determinant of tumorigenesis in glioma patients.

The diagnosis and prognosis values of WNT mRNA expression in colon adenocarcinoma

WNT family genes have participated in the progression and development of many cancers, however, the association between colon adenocarcinoma (COAD) and WNTs have been rarely reported. This study investigated the significance of WNT genes expression in COAD from the standpoint of diagnosis and prognosis. The RNA-sequencing dataset of COAD was downloaded from The Cancer Genome Atlas and University of California, Santa Cruz Xena browser. The biology functions of WNT genes were investigated by biological analysis. Biological analysis of WNT family genes indicated that WNT genes were noticeably enriched in the complex process of WNT signaling pathway. The Pearson correlation analysis suggested WNT1 and WNT9B had a strong correlation. And receiver operating characteristic curves suggested that most of the genes could serve as a significant diagnostic makers in COAD (P < .05), especially WNT2 and WNT7B had high diagnostic values that the area under curve were 0.997 (95% confidence interval [0.994-1.000]) and 0.961 (95%CI [0.939-0.983]), respectively. And our multivariate survival analysis suggested the downregulated of WNT10B (P < .05) showed a favor prognosis in COAD overall survival. And the risk score model predicted that the upregulated expression of WNT10B might increase the risk of death. The very study we had conducted suggested that WNT genes had a certain connection with the diagnosis and prognosis of COAD. The messenger RNA expression of WNT2 and WNT7B might become potentially diagnostic biomarkers, and WNT10B might serve as an independent prognosis indicator for COAD.

A review of predictive, prognostic and diagnostic biomarkers for brain tumours: towards personalised and targeted cancer therapy

Background:

Brain tumours are relatively rare disease but present a large medical challenge as there is currently no method for early detection of the tumour and are typically not diagnosed until patients have progressed to symptomatic stage which significantly decreases chances of survival and also minimises treatment efficacy. However, if brain cancers can be diagnosed at early stages and also if clinicians have the potential to prospectively identify patients likely to respond to specific treatments, then there is a very high potential to increase patients’ treatment efficacy and survival. In recent years, there have been several investigations to identify biomarkers for brain cancer risk assessment, early detection and diagnosis, the likelihood of identifying which group of patients will benefit from a particular treatment and monitoring patient response to treatment.

Materials and methods:

This paper reports on a review of 21 current clinical and emerging biomarkers used in risk assessment, screening for early detection and diagnosis, and monitoring the response of treatment of brain cancers.

Conclusion:

Understanding biomarkers, molecular mechanisms and signalling pathways can potentially lead to personalised and targeted treatment via therapeutic targeting of specific genetic aberrant pathways which play key roles in malignant brain tumour formation. The future holds promising for the use of biomarker analysis as a major factor for personalised and targeted brain cancer treatment, since biomarkers have the potential to measure early disease detection and diagnosis, the risk of disease development and progression, improved patient stratification for various treatment paradigms, provide accurate information of patient response to a specific treatment and inform clinicians about the likely outcome of a brain cancer diagnosis independent of the treatment received.

Biological Functions of TNKS1 and Its Relationship with Wnt/β-Catenin Pathway in Astrocytoma

Background

Tankyrase1 (TNKS1), which often shows abnormal expression in many malignant tumor cells, plays an important role in tumor progression. In our previous study, we found that TNKS1 is also closely related to pathologic grade in human astrocytoma and its expression level is positively correlated with the Wnt/β-catenin pathway. This study is aimed to further elucidate the biological functions of TNKS1 as well as its relationship with the Wnt/β-catenin pathway.

Methods

TNSK1 overexpression and knockdown vectors were constructed and transfected into glioblastoma cell lines U251 MG and U87, respectively. Viability, apoptosis, cell cycle and cell invasiveness in the treated cells were investigated.

Results

In comparison with untreated cells, U251 and U87 cells overexpressing TNSK1 showed significantly increased cell viability and decreased apoptosis, while the TNKS1 knockdown U251 and U87 cells had reduced cell invasive ability and increased apoptosis, respectively. In addition, immunoprecipitation study showed that TNKS1 could be detected by β-catenin antibody after pull-down, indicating that TNKS1 directly interacts with β-catenin, further indicating that TNKS1 could be regarded as a positive regulator of the Wnt/β-catenin pathway in astrocytoma. Moreover, knockdown of TNKS1 in U251 and U87 cells also leads to suppressed Wnt/β-catenin signaling, and subsequent decrease of cell growth and proliferation, reduced invasion ability and increased apoptosis.

Conclusion

Our findings suggest that TNKS1 might be a potential new therapeutic target for human astrocytoma in gene therapy.

The human cytomegalovirus-encoded G protein-coupled receptor UL33 exhibits oncomodulatory properties

Herpesviruses can rewire cellular signaling in host cells by expressing viral G protein-coupled receptors (GPCRs). These viral receptors exhibit homology to human chemokine receptors, but some display constitutive activity and promiscuous G protein coupling. Human cytomegalovirus (HCMV) has been detected in multiple cancers, including glioblastoma, and its genome encodes four GPCRs. One of these receptors, US28, is expressed in glioblastoma and possesses constitutive activity and oncomodulatory properties. UL33, another HCMV-encoded GPCR, also displays constitutive signaling via Gα_q, Gα_i, and Gα_s proteins. However, little is known about the nature and functional effects of UL33-driven signaling. Here, we assessed UL33's signaling repertoire and oncomodulatory potential. UL33 activated multiple proliferative, angiogenic, and inflammatory signaling pathways in HEK293T and U251 glioblastoma cells. Notably, upon infection, UL33 contributed to HCMV-mediated STAT3 activation. Moreover, UL33 increased spheroid growth in vitro and accelerated tumor growth in different in vivo tumor models, including an orthotopic glioblastoma xenograft model. UL33-mediated signaling was similar to that stimulated by US28; however, UL33-induced tumor growth was delayed. Additionally, the spatiotemporal expression of the two receptors only partially overlapped in HCMV-infected glioblastoma cells. In conclusion, our results unveil that UL33 has broad signaling capacity and provide mechanistic insight into its functional effects. UL33, like US28, exhibits oncomodulatory properties, elicited via constitutive activation of multiple signaling pathways. UL33 and US28 might contribute to HCMV's oncomodulatory effects through complementing and converging cellular signaling, and hence UL33 may represent a promising drug target in HCMV-associated malignancies.

Apigenin inhibits fibroblast proliferation and reduces epidural fibrosis by regulating Wnt3a/β-catenin signaling pathway

BACKGROUND

Failed back surgery syndrome (FBSS) is a common complication after the laminectomy. Epidural fibrosis is the major cause of lower back pain and other complications. Numerous studies have shown that apigenin (API) could treat various fibrotic diseases by regulating various signaling pathways, whereas no study has discussed whether API can inhibit fibroblast proliferation and reduce epidural fibrosis after the laminectomy by regulating Wnt3a/β-catenin signaling pathway.

METHODS

Human fibroblasts were cultured and treated with API in different concentrations for 24 h. CCK-8 detection and EdU incorporation assay were performed to detect cell viability and cell proliferation. Western blotting analysis was applied to detect expressions of proliferative proteins, Wnt3a, and its downstream proteins. Moreover, the Wnt3a gene was overexpressed in fibroblasts to define the relationship between Wnt3a/β-catenin signaling pathway and fibroblast proliferation. Wnt3a overexpressed fibroblasts were treated with API to verify if it could reverse the effects of API treatment. Twenty-four Sprague-Dawley rats were randomly divided into four groups. Laminectomy was performed and the rats were gavaged with different doses of API or 5% sodium carboxyl methyl cellulose (CMC-Na) solution for 1 month. The abilities of API to inhibit fibroblast proliferation and to reduce epidural fibrosis were evaluated using histological and immunohistochemical analysis.

RESULTS

CCK-8 detection and EdU incorporation assay demonstrated that API could inhibit the viability and proliferation rate of fibroblasts in a concentration-dependent manner. The Western blotting analysis revealed that API could inhibit the expressions of PCNA, cyclinD1, Wnt3a, and its downstream proteins. The overexpression of Wnt3a in fibroblasts could upregulate the expressions of proliferative proteins such as PCNA and cyclinD1. The inhibitory effect of API on PCNA, Wnt3a, and its downstream proteins was partially reversed by overexpression of Wnt3a. Moreover, the results of the histological and immunohistochemical analysis revealed that API could reduce the epidural fibrosis in rats by inhibiting fibroblast proliferation in a dose-dependent manner.

CONCLUSIONS

API can inhibit fibroblast proliferation and reduce epidural fibrosis by suppressing Wnt3a/β-catenin signaling pathway, which can be adopted as a new option to prevent epidural fibrosis after the laminectomy.

miR-516a-3p inhibits breast cancer cell growth and EMT by blocking the Pygo2/Wnt signalling pathway

miR‐516a‐3p has been reported to play a suppressive role in several types of human tumours. However, the expression level, biological function and fundamental mechanisms of miR‐516a‐3p in breast cancer remain unclear. In the present study, we found that miR‐516a‐3p expression was down‐regulated and Pygopus2 (Pygo2) expression was up‐regulated in human breast cancer tissues and cells. Through analysing the clinicopathological characteristics, we demonstrated that low miR‐516a‐3p expression or positive Pygo2 expression was a predictor of poor prognosis for patients with breast cancer. The results of a dual luciferase reporter assay and Western blot analysis indicated that Pygo2 was a target gene of miR‐516a‐3p. Moreover, overexpression of miR‐516a‐3p inhibited cell growth, migration and invasion as well as epithelial‐mesenchymal transition (EMT) of breast cancer cells, whereas reduced miR‐516a‐3p expression promoted breast cancer cell growth, migration, invasion and EMT. Furthermore, we showed that miR‐516a‐3p suppressed cell proliferation, metastasis and EMT of breast cancer cells by inhibiting Pygo2 expression. We confirmed that miR‐516a‐3p exerted an anti‐tumour effect by inhibiting the activation of the Wnt/β‐catenin pathway. Finally, xenograft tumour models were used to show that miR‐516a‐3p inhibited breast cancer cell growth and EMT via suppressing the Pygo2/Wnt signalling pathway. Taken together, these results show that miR‐516a‐3p inhibits breast cancer cell growth, metastasis and EMT by blocking the Pygo2/ Wnt/β‐catenin pathway.

Oligonucleotide Therapeutics as a New Class of Drugs for Malignant Brain Tumors: Targeting mRNAs, Regulatory RNAs, Mutations, Combinations, and Beyond

Malignant brain tumors are rapidly progressive and often fatal owing to resistance to therapies and based on their complex biology, heterogeneity, and isolation from systemic circulation. Glioblastoma is the most common and most aggressive primary brain tumor, has high mortality, and affects both children and adults. Despite significant advances in understanding the pathology, multiple clinical trials employing various treatment strategies have failed. With much expanded knowledge of the GBM genome, epigenome, and transcriptome, the field of neuro-oncology is getting closer to achieve breakthrough-targeted molecular therapies. Current developments of oligonucleotide chemistries for CNS applications make this new class of drugs very attractive for targeting molecular pathways dysregulated in brain tumors and are anticipated to vastly expand the spectrum of currently targetable molecules. In this chapter, we will overview the molecular landscape of malignant gliomas and explore the most prominent molecular targets (mRNAs, miRNAs, lncRNAs, and genomic mutations) that provide opportunities for the development of oligonucleotide therapeutics for this class of neurologic diseases. Because malignant brain tumors focally disrupt the blood-brain barrier, this class of diseases might be also more susceptible to systemic treatments with oligonucleotides than other neurologic disorders and, thus, present an entry point for the oligonucleotide therapeutics to the CNS. Nevertheless, delivery of oligonucleotides remains a crucial part of the treatment strategy. Finally, synthetic gRNAs guiding CRISPR-Cas9 editing technologies have a tremendous potential to further expand the applications of oligonucleotide therapeutics and take them beyond RNA targeting.

Antiproliferative Effects of Ellagic Acid on DU145 Cells

Background:

Prostate Cancer (PC) represents a leading cause of tumor-related death among men in the Western world. Above all, DU145 cell line represents the most particular cells model of PC, derived from a central nervous system metastasis. In recent years, functional and healthy diet has gained a pivotal role in society, allowing the possibility to deal with cancer before its emergence or progression, profiting by anti-tumor properties of dietary phytochemicals. Among them, Ellagic Acid (EA) is found in several fruits and vegetables, whose juice demonstrated antioxidant, anti-carcinogenic and anti-fibrotic properties.

Methods:

DU145 prostate cancer cell line was used to determine the effects of ellagic acid on cell viability. In order to evaluate metastatic feature of DU145, VEGF-A and OPG levels by ELISA assay were assessed. Expression of β-catenin, HO-1, HO-2 and SIRT1, markers of proliferative and defense capacities, were determined by western blotting. To strengthen the study, cell transfection with siRNA β-catenin was performed.

Results:

In the presence of EA, the viability of DU145 cells was reduced by about 40 and 50%, respectively after the exposure to 50 and 100 μM concentrations. We also observed a reduction of both levels of VEGF-A and OPG, confirming the important role of EA in facing the metastasis development. EA treatment (50 μM) induced a significant reduction of β-catenin and SIRT1 levels and, similarly, there was a decrease of HO protein expression, more pronounced for HO-2, showing EA activity on the proliferative feature of DU145 cells. Knockdown of β-catenin by siRNA, in the presence of EA treatment, inhibited cell proliferation.

Conclusion:

Ellagic acid exhibits significant antiproliferative effects in ourin vitromodel of prostate cancer’s metastasis, suggesting that, the use of EA as a multitarget natural compound, may represent a possible strategy for cancer chemoprevention.

MicroRNA regulating stanniocalcin-1 is a metastasis and dissemination promoting factor in glioblastoma

BACKGROUND

MicroRNAs (miRs) regulate many biological processes, such as invasion, angiogenesis, and metastasis. Glioblastoma (GBM) patients with metastasis/metastatic dissemination have a very poor prognosis; therefore, inhibiting metastasis/metastatic dissemination has become an important therapeutic strategy for GBM treatment.

METHODS

Using 76 GBM tissues, we examined the expression levels of 23 GBM-related miRs and compared the miRs' expression levels between GBMs with metastasis/metastatic dissemination and GBMs without metastasis/metastatic dissemination. Using the bioinformatics web site, we searched the target genes of miRs. To analyze the function of target gene, several biological assays and survival analysis by the Kaplan-Meier method were performed.

RESULTS

We found that eight miRs were significantly decreased in GBM with metastasis/metastatic dissemination. By the bioinformatics analysis, we identified stanniocalcin-1 (STC1) as the most probable target gene against the combination of these miRs. Four miRs (miR-29B, miR-34a, miR-101, and miR-137) have predictive binding sites in STC1 mRNA, and mRNA expression of STC1 was downregulated by mimics of these miRs. Also, mimics of these miRs and knockdown of STC1 by siRNA suppressed invasion in GBM cells. GBM with metastasis/metastatic dissemination had significantly higher levels of STC1 than GBM without metastasis/metastatic dissemination. Finally, Kaplan-Meier analysis demonstrated that GBMs with high STC1 level had significantly shorter survival than GBMs with low STC1 level.

CONCLUSIONS

STC1 may be a novel metastasis/metastatic dissemination promoting factor regulated by several miRs in GBM. Because STC1 is a secreted glycoprotein and functions via the autocrine/paracrine signals, inhibiting STC1 signal may become a novel therapeutic strategy for GBM.

The Opposing Contribution of SMS1 and SMS2 to Glioma Progression and Their Value in the Therapeutic Response to 2OHOA

Background: 2-Hydroxyoleic acid (2OHOA) is particularly active against glioblastoma multiforme (GBM) and successfully finished a phase I/IIA trial in patients with glioma and other advanced solid tumors. However, its mechanism of action is not fully known. Methods: The relationship between SMS1 and SMS2 expressions (mRNA) and overall survival in 329 glioma patients was investigated, and so was the correlation between SMS expression and 2OHOA's efficacy. The opposing role of SMS isoforms in 2OHOA's mechanism of action and in GBM cell growth, differentiation and death, was studied overexpressing or silencing them in human GBM cells. Results: Patients with high-SMS1 plus low-SMS2 expression had a 5-year survival ~10-fold higher than patients with low-SMS1 plus high-SMS2 expression. SMS1 and SMS2 also had opposing effect on GBM cell survival and 2OHOA's IC₅₀ correlated with basal SMS1 levels and treatment induced changes in SMS1/SMS2 ratio. SMSs expression disparately affected 2OHOA's cancer cell proliferation, differentiation, ER-stress and autophagy. Conclusions: SMS1 and SMS2 showed opposite associations with glioma patient survival, glioma cell growth and response to 2OHOA treatment. SMSs signature could constitute a valuable prognostic biomarker, with high SMS1 and low SMS2 being a better disease prognosis. Additionally, low basal SMS1 mRNA levels predict positive response to 2OHOA.

Vasculogenesis and angiogenesis initiation under normoxic conditions through Wnt/β-catenin pathway in gliomas

The canonical Wnt/β-catenin pathway is up-regulated in gliomas and involved in proliferation, invasion, apoptosis, vasculogenesis and angiogenesis. Nuclear β-catenin accumulation correlates with malignancy. Hypoxia activates hypoxia-inducible factor (HIF)-1α by inhibiting HIF-1α prolyl hydroxylation, which promotes glycolytic energy metabolism, vasculogenesis and angiogenesis, whereas HIF-1α is degraded by the HIF prolyl hydroxylase under normoxic conditions. We focus this review on the links between the activated Wnt/β-catenin pathway and the mechanisms underlying vasculogenesis and angiogenesis through HIF-1α under normoxic conditions in gliomas. Wnt-induced epidermal growth factor receptor/phosphatidylinositol 3-kinase (PI3K)/Akt signaling, Wnt-induced signal transducers and activators of transcription 3 (STAT3) signaling, and Wnt/β-catenin target gene transduction (c-Myc) can activate HIF-1α in a hypoxia-independent manner. The PI3K/Akt/mammalian target of rapamycin pathway activates HIF-1α through eukaryotic translation initiation factor 4E-binding protein 1 and STAT3. The β-catenin/T-cell factor 4 complex directly binds to STAT3 and activates HIF-1α, which up-regulates the Wnt/β-catenin target genes cyclin D1 and c-Myc in a positive feedback loop. Phosphorylated STAT3 by interleukin-6 or leukemia inhibitory factor activates HIF-1α even under normoxic conditions. The activation of the Wnt/β-catenin pathway induces, via the Wnt target genes c-Myc and cyclin D1 or via HIF-1α, gene transactivation encoding aerobic glycolysis enzymes, such as glucose transporter, hexokinase 2, pyruvate kinase M2, pyruvate dehydrogenase kinase 1 and lactate dehydrogenase-A, leading to lactate production, as the primary alternative of ATP, at all oxygen levels, even in normoxic conditions. Lactate released by glioma cells via the monocarboxylate lactate transporter-1 up-regulated by HIF-1α and lactate anion activates HIF-1α in normoxic endothelial cells by inhibiting HIF-1α prolyl hydroxylation and preventing HIF labeling by the von Hippel-Lindau protein. Increased lactate with acid environment and HIF-1α overexpression induce the vascular endothelial growth factor (VEGF) pathway of vasculogenesis and angiogenesis under normoxic conditions. Hypoxia and acidic pH have no synergistic effect on VEGF transcription.

WNT6 is a novel oncogenic prognostic biomarker in human glioblastoma

Glioblastoma (GBM) is a universally fatal brain cancer, for which novel therapies targeting specific underlying oncogenic events are urgently needed. While the WNT pathway has been shown to be frequently activated in GBM, constituting a potential therapeutic target, the relevance of WNT6, an activator of this pathway, remains unknown.

Methods: WNT6 protein and mRNA levels were evaluated in GBM. WNT6 levels were silenced or overexpressed in GBM cells to assess functional effects in vitro and in vivo. Phospho-kinase arrays and TCF/LEF reporter assays were used to identify WNT6-signaling pathways, and significant associations with stem cell features and cancer-related pathways were validated in patients. Survival analyses were performed with Cox regression and Log-rank tests. Meta-analyses were used to calculate the estimated pooled effect.

Results: We show that WNT6 is significantly overexpressed in GBMs, as compared to lower-grade gliomas and normal brain, at mRNA and protein levels. Functionally, WNT6 increases typical oncogenic activities in GBM cells, including viability, proliferation, glioma stem cell capacity, invasion, migration, and resistance to temozolomide chemotherapy. Concordantly, in in vivo orthotopic GBM mice models, using both overexpressing and silencing models, WNT6 expression was associated with shorter overall survival, and increased features of tumor aggressiveness. Mechanistically, WNT6 contributes to activate typical oncogenic pathways, including Src and STAT, which intertwined with the WNT pathway may be critical effectors of WNT6-associated aggressiveness in GBM. Clinically, we establish WNT6 as an independent prognostic biomarker of shorter survival in GBM patients from several independent cohorts.

Conclusion: Our findings establish WNT6 as a novel oncogene in GBM, opening opportunities to develop more rational therapies to treat this highly aggressive tumor.

Opposite Interplay Between the Canonical WNT/β-Catenin Pathway and PPAR Gamma: A Potential Therapeutic Target in Gliomas

In gliomas, the canonical Wingless/Int (WNT)/β-catenin pathway is increased while peroxisome proliferator-activated receptor gamma (PPAR-γ) is downregulated. The two systems act in an opposite manner. This review focuses on the interplay between WNT/β-catenin signaling and PPAR-γ and their metabolic implications as potential therapeutic target in gliomas. Activation of the WNT/β-catenin pathway stimulates the transcription of genes involved in proliferation, invasion, nucleotide synthesis, tumor growth, and angiogenesis. Activation of PPAR-γ agonists inhibits various signaling pathways such as the JAK/STAT, WNT/β-catenin, and PI3K/Akt pathways, which reduces tumor growth, cell proliferation, cell invasiveness, and angiogenesis. Nonsteroidal anti-inflammatory drugs, curcumin, antipsychotic drugs, adiponectin, and sulforaphane downregulate the WNT/β-catenin pathway through the upregulation of PPAR-γ and thus appear to provide an interesting therapeutic approach for gliomas. Temozolomide (TMZ) is an antiangiogenic agent. The downstream action of this opposite interplay may explain the TMZ-resistance often reported in gliomas.

Downregulation of N‑Myc inhibits neuroblastoma cell growth via the Wnt/β‑catenin signaling pathway

Neuroblastoma, one of the most common types of cancer in childhood, is commonly treated with surgery, radiation and chemotherapy. However, prognosis and survival remain poor for children with high‑risk neuroblastoma. Therefore, the identification of novel, effective therapeutic targets is necessary. N‑Myc, a proto‑oncogene protein encoded by the v‑myc avial myelocytomatosis viral oncogene neuroblastoma derived homolog (MYCN) gene, is associated with tumorigenesis. In the present study, the effect of N‑Myc silencing on MYCN‑amplified CHP134 and BE‑2C neuroblastoma cells was evaluated, and the underlying molecular mechanism was investigated. N‑Myc was successfully knocked down using an N‑Myc‑specific small interfering RNA, the efficacy of interference efficiency confirmed by reverse transcription‑quantitative polymerase chain reaction and western blotting. Cell viability was evaluated by MTT assay and apoptosis was measured by ELISA assay. The results indicated that MYCN silencing significantly decreased cell viability and promoted apoptosis. Subsequently, the expression levels of key Wnt/β‑catenin signaling pathway proteins were detected by western blotting, and MYCN silencing was demonstrated to inhibit Wnt/β‑catenin signaling, decreasing the expression ofanti‑apoptosis proteins and increasing the expression of pro‑apoptosis protein. This suggested that N‑Myc regulated survival and growth of CHP134 and BE‑2C neuroblastoma cells, potentially through Wnt/β‑catenin signaling. Furthermore, associated proteins, N‑Myc and STAT interactor and dickkopf Wnt signaling pathway inhibitor 1, were demonstrated to be involved in this regulation. Therefore, N‑Myc and its downstream targets may provide novel therapeutic targets for the treatment of neuroblastoma.

Propofol inhibits Wnt signaling and exerts anticancer activity in glioma cells

Aberrant activation of Wnt signaling is implicated in gliomagenesis. Propofol, the most commonly used intravenous anesthetic agent in clinics, exhibits potent antitumor activity in a variety of cancer cells through different mechanisms. However, the role of propofol on Wnt signaling and glioma cell growth remains to be fully elucidated. In the present study, propofol was identified as a potent inhibitor of Wnt signaling. In 293T cells transfected with Wnt1 or Wnt3 expression plasmids or treated with Wnt3A-conditioned medium, propofol significantly inhibited the transcriptional activity of the SuperTopFlash reporter and the expression of Wnt target genes. The inhibitory effect of propofol on Wnt signaling was also observed in glioma cells. Further experiments demonstrated that propofol suppressed glioma cell growth by decreasing cell proliferation and enhancing cell apoptosis. Finally, the potential antitumor efficiency of propofol was confirmed using xenograft experiments in vivo. Taken together, the results indicated a novel mechanism for the anticancer activity of propofol and provide supporting evidence for its use as a prospective anticancer drug to treat glioma in patients with deregulated Wnt signaling.

miR-129-5p targets Wnt5a to block PKC/ERK/NF-κB and JNK pathways in glioblastoma

Therapeutic application of microRNAs (miRNAs) in Wnt-driven glioma has been valuable; however, their specific roles and mechanisms have not been completely investigated. Real-time quantitative PCR (RT-qPCR) was used to analyse the expression of microRNA-129-5p (miR-129-5p) in human glioma samples. Cell-Counting Kit 8 (CCK-8), flow cytometry, EdU, angiogenesis, Transwell invasion, wound healing, in vitro 3D migration and neurosphere formation assays were employed to assess the role of miR-129-5p in glioblastoma multiforme (GBM) cells. Moreover, we performed the luciferase reporter assay and the RNA-ChIP (chromatin immunoprecipitation) assay to confirm whether Wnt5a was a direct target of miR-129-5p. We also confirmed the correlation between the expression profile of miR-129-5p and Wnt5a in glioma patients from the Chinese Glioma Genome Atlas (CGGA) and investigated the overall survival of GBM patients using two data sets, namely, TCGA and GSE16011, according to their Wnt5a expression status. MiR-129-5p expression levels were downregulated and inversely correlated with Wnt5a expression levels in CGGA glioma patients. Restored expression of miR-129-5p blocked GBM cell proliferation, invasion, migration, angiogenesis, neurosphere formation and resistance to temozolomide. We reported that miR-129-5p directly targeted Wnt5a in glioma. Furthermore, we observed that overexpression of miR-129-5p inhibited the expression of Wnt5a, thus blocking the protein kinase C(PKC)/ERK/NF-κB and JNK pathways. Inhibiting Wnt5a rescued the effects of miR-129-5p loss and increased Wnt5a expression was associated with reduced overall survival of GBM patients. We also demonstrated the inhibitory effect of miR-129-5p on tumour growth in GBM using an in vivo model. The miR-129-5p/Wnt5a-axis-mediated PKC/ERK/NF-κB and JNK pathways have therapeutic potential in GBM treatment.

Nerve growth factor modulates the tumor cells migration in ovarian cancer through the WNT/β-catenin pathway

Nerve growth factor (NGF)/nerve growth factor receptors (NGFRs) axis and canonical WNT/β-catenin pathway have shown to play crucial roles in tumor initiation, progression and prognosis. But little did we know the relationship between them in modulation of tumor progress. In this report, we found that NGF/NGFRs and β-catenin were coexpression in ovarian cancer cell lines, and NGF can decrease the expression level of β-catenin and affect its activities, which may be related to the NGF-induced down-regulation of B-cell CLL/lymphoma 9-like (BCL9L, BCL9-2). Furthermore, NGF can also increase or decrease the downstream target gene expression levels of WNT/β-catenin depending on the cell types. Especially, we created a novel in vitro cell growth model based on a microfluidic device to intuitively observe the effects of NGF/NGFRs on the motility behaviors of ovarian cancer cells. The results showed that the migration area and maximum distance into three dimensional (3D) matrigel were decreased in CAOV3 and OVCAR3 cells, but increased in SKOV3 cells following the stimulation with NGF. In addition, we found that the cell colony area was down-regulated in CAOV3 cells, however, it was augmented in OVCAR3 cells after treatment with NGF. The inhibitors of NGF/NGFRs, such as Ro 08-2750, K252a and LM11A-31,can all block NGF-stimulated changes of gene expression or migratory behavior on ovarian cancer cells. The different results among ovarian cancer cells illustrated the heterogeneity and complexity of ovarian cancer. Collectively, our results suggested for the first time that NGF is functionally linked to β-catenin in the migration of human ovarian cancer cells, which may be a novel therapeutic perspective to prevent the spread of ovarian carcinomas by studying the interaction between NGF/NGFRs and canonical WNT/β-catenin signaling.

MicroRNA-target cross-talks: Key players in glioblastoma multiforme

The role of microRNAs in brain cancer is still naive. Some act as oncogene and others as tumor suppressors. Discovery of efficient biomarkers is mandatory to debate that aggressive disease. Bioinformatically selected microRNAs and their targets were investigated to evaluate their putative signature as diagnostic and prognostic biomarkers in primary glioblastoma multiforme. Expression of a panel of seven microRNAs (hsa-miR-34a, hsa-miR-16, hsa-miR-17, hsa-miR-21, hsa-miR-221, hsa-miR-326, and hsa-miR-375) and seven target genes ( E2F3, PI3KCA, TOM34, WNT5A, PDCD4, DFFA, and EGFR) in 43 glioblastoma multiforme specimens were profiled compared to non-cancer tissues via quantitative reverse transcription-polymerase chain reaction. Immunohistochemistry staining for three proteins (VEGFA, BAX, and BCL2) was performed. Gene enrichment analysis identified the biological regulatory functions of the gene panel in glioma pathway. MGMT ( O-6-methylguanine-DNA methyltransferase) promoter methylation was analyzed for molecular subtyping of tumor specimens. Our data demonstrated a significant upregulation of five microRNAs (hsa-miR-16, hsa-miR-17, hsa-miR-21, hsa-miR-221, and hsa-miR-375), three genes ( E2F3, PI3KCA, and Wnt5a), two proteins (VEGFA and BCL2), and downregulation of hsa-miR-34a and three other genes ( DFFA, PDCD4, and EGFR) in brain cancer tissues. Receiver operating characteristic analysis revealed that miR-34a (area under the curve = 0.927) and miR-17 (area under the curve = 0.900) had the highest diagnostic performance, followed by miR-221 (area under the curve = 0.845), miR-21 (area under the curve = 0.836), WNT5A (area under the curve = 0.809), PDCD4 (area under the curve = 0.809), and PI3KCA (area under the curve = 0.800). MGMT promoter methylation status was associated with high miR-221 levels. Moreover, patients with VEGFA overexpression and downregulation of TOM34 and BAX had poor overall survival. Nevertheless, miR-17, miR-221, and miR-326 downregulation were significantly associated with high recurrence rate. Multivariate analysis by hierarchical clustering classified patients into four distinct groups based on gene panel signature. In conclusion, the explored microRNA-target dysregulation could pave the road toward developing potential therapeutic strategies for glioblastoma multiforme. Future translational and functional studies are highly recommended to better understand the complex bio-molecular signature of this difficult-to-treat tumor.

Expression profile and clinical significance of Wnt signaling in human gliomas

Wnt signaling has been identified as a critical regulator of human tumor development in vitro. However, there remains a lack of studies systematically examining the expression pattern and clinical relevance of the core molecules of Wnt signaling in glioma tissues. In the present study, it was identified that the mRNA expression levels of Wnt3a and 5a, and their receptors frizzled 2, 6 and 7 increased, whereas Wnt7b was markedly decreased in glioma relative to non-tumor tissue. The mRNA levels of β-catenin, adenomatous polyposis coli gene product, glycogen synthase kinase 3β (GSK3β) and AXIN1 and its target genes cyclin D1 and AXIN2 did not differ. Similarly, the protein levels of Wnt2b, 3a and 5a were increased in gliomas, while β-catenin, GSK3β and cyclin D1 were not. Furthermore, based on data from the R2: Genomics Analysis and Visualization Platform, the expression of Wnt2b and 5a, and frizzled 2, 6 and 7 were highly associated with the prognosis of patients with glioma. Taken together, the results of the present study demonstrate that β-catenin is not upregulated in gliomas and that the Wnt signaling pathway may promote glioma development via noncanonical or alternative pathways.

Challenges and Recent Advances in Medulloblastoma Therapy

Medulloblastoma (MB) is the most common childhood brain tumor, which occurs in the posterior fossa. MB tumors are highly heterogeneous and have diverse genetic make-ups, with differential microRNA (miRNA) expression profiles and variable prognoses. MB can be classified into four subgroups, each with different origins, pathogenesis, and potential therapeutic targets. miRNA and small-molecule targeted therapies have emerged as a potential new therapeutic paradigm in MB treatment. However, the development of chemoresistance due to surviving cancer stem cells and dysregulation of miRNAs remains a challenge. Combination therapies using multiple drugs and miRNAs could be effective approaches. In this review we discuss various MB subtypes, barriers, and novel therapeutic options which may be less toxic than current standard treatments.