Deregulated proliferation and differentiation in brain tumors

Aberrant DNA methylation distorts developmental trajectories in atypical teratoid/rhabdoid tumors

Atypical teratoid/rhabdoid tumors (AT/RTs) are pediatric brain tumors known for their aggressiveness and aberrant but still unresolved epigenetic regulation. To better understand their malignancy, we investigated how AT/RT-specific DNA hypermethylation was associated with gene expression and altered transcription factor binding and how it is linked to upstream regulation. Medulloblastomas, choroid plexus tumors, pluripotent stem cells, and fetal brain were used as references. A part of the genomic regions, which were hypermethylated in AT/RTs similarly as in pluripotent stem cells and demethylated in the fetal brain, were targeted by neural transcriptional regulators. AT/RT-unique DNA hypermethylation was associated with polycomb repressive complex 2 and linked to suppressed genes with a role in neural development and tumorigenesis. Activity of the several NEUROG/NEUROD pioneer factors, which are unable to bind to methylated DNA, was compromised via the suppressed expression or DNA hypermethylation of their target sites, which was also experimentally validated for NEUROD1 in medulloblastomas and AT/RT samples. These results highlight and characterize the role of DNA hypermethylation in AT/RT malignancy and halted neural cell differentiation.

Radiation-Induced Cellular Plasticity: A Strategy for Combatting Glioblastoma

Glioblastoma is the deadliest brain cancer in adults and almost all patients succumb to the tumor. While surgery followed by chemo-radiotherapy significantly delays disease progression, these treatments do not lead to long-term tumor control and targeted therapies or biologics have so far failed to further improve survival. Utilizing a transient radiation-induced state of multipotency we used the adenylcyclase activator forskolin to alter the cellular fate of glioma cells in response to radiation. The combined treatment induced the expression of neuronal markers in glioma cells, reduced proliferation and led to a distinct gene expression profile. scRNAseq revealed that the combined treatment forced glioma cells into a microglia- and neuron-like phenotypes. In vivo this treatment led to a loss of glioma stem cells and prolonged median survival in mouse models of glioblastoma. Collectively, our data suggest that revisiting a differentiation therapy with forskolin in combination with radiation could lead to clinical benefit.

Gliomas: a reflection of temporal gliogenic principles

The hijacking of early developmental programs is a canonical feature of gliomas where neoplastic cells resemble neurodevelopmental lineages and possess mechanisms of stem cell resilience. Given these parallels, uncovering how and when in developmental time gliomagenesis intersects with normal trajectories can greatly inform our understanding of tumor biology. Here, we review how elapsing time impacts the developmental principles of astrocyte (AS) and oligodendrocyte (OL) lineages, and how these same temporal programs are replicated, distorted, or circumvented in pathological settings such as gliomas. Additionally, we discuss how normal gliogenic processes can inform our understanding of the temporal progression of gliomagenesis, including when in developmental time gliomas originate, thrive, and can be pushed towards upon therapeutic coercion.

Calcium dynamics at the neural cell primary cilium regulate Hedgehog signaling-dependent neurogenesis in the embryonic neural tube

The balance between neural stem cell proliferation and neuronal differentiation is paramount for the appropriate development of the nervous system. Sonic hedgehog (Shh) is known to sequentially promote cell proliferation and specification of neuronal phenotypes, but the signaling mechanisms responsible for the developmental switch from mitogenic to neurogenic have remained unclear. Here, we show that Shh enhances Ca2+ activity at the neural cell primary cilium of developing Xenopus laevis embryos through Ca2+ influx via transient receptor potential cation channel subfamily C member 3 (TRPC3) and release from intracellular stores in a developmental stage-dependent manner. This ciliary Ca2+ activity in turn antagonizes canonical, proliferative Shh signaling in neural stem cells by down-regulating Sox2 expression and up-regulating expression of neurogenic genes, enabling neuronal differentiation. These discoveries indicate that the Shh-Ca2+-dependent switch in neural cell ciliary signaling triggers the switch in Shh action from canonical-mitogenic to neurogenic. The molecular mechanisms identified in this neurogenic signaling axis are potential targets for the treatment of brain tumors and neurodevelopmental disorders.

Construction of immune cell infiltration protein network based on clinical low grade glioma cases

Many researchers have studied low-grade glioma and the immune microenvironment have been studied by many researchers. Recent studies suggest that macrophages and dendritic cells trigger part of the local immune dysregulation in the tumor microenvironment, and they have been polarized into a mixed pro-inflammatory and immunosuppressive phenotype. It is suggested that the degree of immune infiltration is related to the survival, therapeutic effect, and prognosis of patients. This opens up new avenues for cancer treatment. On the basis of immune infiltration degree, a protein interaction network (PIN) and a prognosis model were established, and we chose the top 20 pathways from enrichment analysis to provide potential targets for glioma clinical treatment.

Inhibiting PDE7A Enhances the Protective Effects of Neural Stem Cells on Neurodegeneration and Memory Deficits in Sevoflurane-Exposed Mice

Sevoflurane is widely used in general anesthesia, especially for children. However, prolonged exposure to sevoflurane is reported to be associated with adverse effects on the development of brain in infant monkey. Neural stem cells (NSCs), with potent proliferation, differentiation, and renewing ability, provide an encouraging tool for basic research and clinical therapies for neurodegenerative diseases. We aim to explore the functional effects of injecting NSCs with phosphodiesterase 7A (PDE7A) knock-down in infant mice exposed to sevoflurane. The effects of PDE7A in NSCs proliferation and differentiation were determined by cell counting kit-8 (CCK-8) assay and differentiation-related gene expression assay, respectively. The effects of NSCs with modified PDE7A on mice’s long-term memory and learning ability were assessed by behavioral assays. Our data demonstrated that depleting PDE7A promoted, whereas forcing PDE7A suppressed the activation of cAMP/cAMP-response element binding protein (CREB) signaling as well as cell proliferation and neuronal differentiation of NSCs. Inhibition of PDE7A in NSCs exhibited profound improved effects on long-term memory and learning ability of mice exposed to sevoflurane. Our results for the first time show that knock-down of PDE7A improves the neurogenesis of NSCs in vitro and in vivo, and is beneficial for alleviating sevoflurane-induced brain damage in infant mice.

Three-dimensional model of glioblastoma by co-culturing tumor stem cells with human brain organoids

Emerging three-dimensional (3D) cultures of glioblastoma are becoming powerful models to study glioblastoma stem cell behavior and the impact of cell-cell and cell-microenvironment interactions on tumor growth and invasion. Here we describe a method for culturing human glioblastoma stem cells (GSCs) in 3D by co-culturing them with pluripotent stem cell-derived brain organoids. This requires multiple coordinated steps, including the generation of cerebral organoids, and the growth and fluorescence tagging of GSCs. We highlight how to recognize optimal organoid generation and how to efficiently mark GSCs, before describing optimized co-culture conditions. We show that GSCs can efficiently integrate into brain organoids and maintain a significant degree of cell fate heterogeneity, paving the way for the analysis of GSC fate behavior and lineage progression. These results establish the 3D culture system as a viable and versatile GBM model for investigating tumor cell biology and GSC heterogeneity.This article has an associated First Person interview with the first author of the paper.

Trends and challenges in modeling glioma using 3D human brain organoids

The human brain organoids derived from pluripotent cells are a new class of three-dimensional tissue systems that recapitulates several neural epithelial aspects. Brain organoids have already helped efficient modeling of crucial elements of brain development and disorders. Brain organoids’ suitability in modeling glioma has started to emerge, offering another usefulness of brain organoids in disease modeling. Although the current state-of-the organoids mostly reflect the immature state of the brain, with their vast cell diversity, human brain-like cytoarchitecture, feasibility in culturing, handling, imaging, and tractability can offer enormous potential in reflecting the glioma invasion, integration, and interaction with different neuronal cell types. Here, we summarize the current trend of employing brain organoids in glioma modeling and discuss the immediate challenges. Solving them might lay a foundation for using brain organoids as a pre-clinical 3D substrate to dissect the glioma invasion mechanisms in detail.

Image-based state-of-the-art techniques for the identification and classification of brain diseases: a review

Detection and classification methods have a vital and important role in identifying brain diseases. Timely detection and classification of brain diseases enable an accurate identification and effective management of brain impairment. Brain disorders are commonly most spreadable diseases and the diagnosing process is time-consuming and highly expensive. There is an utmost need to develop effective and advantageous methods for brain diseases detection and characterization. Magnetic resonance imaging (MRI), computed tomography (CT), and other various brain imaging scans are used to identify different brain diseases and disorders. Brain imaging scans are the efficient tool to understand the anatomical changes in brain in fast and accurate manner. These different brain imaging scans used with segmentation techniques and along with machine learning and deep learning techniques give maximum accuracy and efficiency. This paper focuses on different conventional approaches, machine learning and deep learning techniques used for the detection, and classification of brain diseases and abnormalities. This paper also summarizes the research gap and problems in the existing techniques used for detection and classification of brain disorders. Comparison and evaluation of different machine learning and deep learning techniques in terms of efficiency and accuracy are also highlighted in this paper. Furthermore, different brain diseases like leukoariaosis, Alzheimer's, Parkinson's, and Wilson's disorder are studied in the scope of machine learning and deep learning techniques.

Organoid Models of Glioblastoma to Study Brain Tumor Stem Cells

Glioblastoma represents an aggressive form of brain cancer characterized by poor prognosis and a 5-year survival rate of only 3–7%. Despite remarkable advances in brain tumor research in the past decades, very little has changed for patients, due in part to the recurrent nature of the disease and to the lack of suitable models to perform genotype-phenotype association studies and personalized drug screening. In vitro culture of cancer cells derived from patient biopsies has been fundamental in understanding tumor biology and for testing the effect of various drugs. These cultures emphasize the role of in vitro cancer stem cells (CSCs), which fuel tumor growth and are thought to be the cause of relapse after treatment. However, it has become clear over the years that a 2D monolayer culture of these CSCs has certain disadvantages, including the lack of heterogeneous cell-cell and cell-environment interactions, which can now be partially overcome by the introduction of 3D organoid cultures. This is a novel and expanding field of research and in this review, I describe the emerging 3D models of glioblastoma. I also discuss their potential to advance our knowledge of tumor biology and CSC heterogeneity, while debating their current limitations.

Role of non-coding RNA networks in leukemia progression, metastasis and drug resistance

Early-stage detection of leukemia is a critical determinant for successful treatment of the disease and can increase the survival rate of leukemia patients. The factors limiting the current screening approaches to leukemia include low sensitivity and specificity, high costs, and a low participation rate. An approach based on novel and innovative biomarkers with high accuracy from peripheral blood offers a comfortable and appealing alternative to patients, potentially leading to a higher participation rate.

Recently, non-coding RNAs due to their involvement in vital oncogenic processes such as differentiation, proliferation, migration, angiogenesis and apoptosis have attracted much attention as potential diagnostic and prognostic biomarkers in leukemia. Emerging lines of evidence have shown that the mutational spectrum and dysregulated expression of non-coding RNA genes are closely associated with the development and progression of various cancers, including leukemia. In this review, we highlight the expression and functional roles of different types of non-coding RNAs in leukemia and discuss their potential clinical applications as diagnostic or prognostic biomarkers and therapeutic targets.

MicroRNA-144 represses gliomas progression and elevates susceptibility to Temozolomide by targeting CAV2 and FGF7

Malignant gliomas are the most common tumor in central nervous system with poor prognosis. Due to the limitation of histological classification in earlier diagnosis and individualized medicine, it is necessary to combine the molecular signatures and the pathological characteristics of gliomas. Lots of microRNAs presented abnormal expression in gliomas and modulated gliomas development. Exploration the miRNAs profile is helpful for the diagnosis, therapy and prognosis of gliomas. It has been demonstrated that miR-144 plays important roles in solid tumors. However, the detail mechanisms remained unrevealed. In this study, we have demonstrated the level of miR-144 decreased in glioma tissues from patients, especially in gliomas with higher grades. MiR-144 was also validated have lower expression in glioma cell lines compared with cortical neuron cell by using qRT-PCR. The in vitro functional experiment indicated miR-144 improved gliomas progression through repressing proliferation, sensitizing to chemotherapeutics and inhibiting metastasis. We further identified fibroblast growth factor 7 (FGF7) and Caveolin 2 (CAV2) were target genes of miR-144 by luciferase reporter assay and western blotting. The mechanisms study suggested forced FGF7 expression elevated Akt activation and decreased reactive oxygen species (ROS) generation. The MTT and cell cycle assay indicated miR-144 suppressed glioma cells proliferation through modulating FGF mediated Akt signaling pathway. Meanwhile, miR-144 promoted Temozolomide (TMZ) induced apoptosis in glioma cells via increasing ROS production by using FACS. On the other hand, CAV2, as another target of miR-144, accelerated glioma cells migration and invasion via promoting glioma cells EMT progress. Retrieved expression of FGF7 or CAV2 rescued the proliferation and migration function mediated by miR-144. Furthermore, the in vivo experiments in PDX models displayed the anti-tumor function of miR-144, which could be retrieved by overexpression of FGF7 and CAV2. Taken together, these findings indicated miR-144 acted as a potential target against gliomas progression and uncovered a novel regulatory mechanism, which may provide a new therapeutic strategy and prognostic indicator for gliomas.

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.

I-8, a novel inhibitor of mutant IDH1, inhibits cancer progression in vitro and in vivo

Isocitrate dehydrogenase 1 mutations have been discovered in an array of hematologic malignancies and solid tumors. These mutations could cause the production of high levels of 2-hydroxyglutarate, which in turn implicated in epigenetic changes and impaired cell differentiation. Here, we described the characterization of compound I-8, a novel mutant IDH1 inhibitor, both in vitro and in vivo. Compound I-8 specifically inhibited 2-HG production, reduced histone methylation levels, induced differentiation and depleted stem characteristics in engineered and endogenous IDH1 mutant cells. In addition, oral administration of I-8 also significantly suppressed 2-HG production and histone methylation with dose of 150 mg/kg. And I-8 treatment also could induce differentiation and attenuate stem characteristics in tumor tissue. Together, these studies indicated that compound I-8 has clinical potential in tumor therapies as a effective mutant IDH1 inhibitor, and provided scientific guidance for the development of mutant IDH1 inhibitor in the future.

A Review on a Deep Learning Perspective in Brain Cancer Classification

A World Health Organization (WHO) Feb 2018 report has recently shown that mortality rate due to brain or central nervous system (CNS) cancer is the highest in the Asian continent. It is of critical importance that cancer be detected earlier so that many of these lives can be saved. Cancer grading is an important aspect for targeted therapy. As cancer diagnosis is highly invasive, time consuming and expensive, there is an immediate requirement to develop a non-invasive, cost-effective and efficient tools for brain cancer characterization and grade estimation. Brain scans using magnetic resonance imaging (MRI), computed tomography (CT), as well as other imaging modalities, are fast and safer methods for tumor detection. In this paper, we tried to summarize the pathophysiology of brain cancer, imaging modalities of brain cancer and automatic computer assisted methods for brain cancer characterization in a machine and deep learning paradigm. Another objective of this paper is to find the current issues in existing engineering methods and also project a future paradigm. Further, we have highlighted the relationship between brain cancer and other brain disorders like stroke, Alzheimer’s, Parkinson’s, and Wilson’s disease, leukoriaosis, and other neurological disorders in the context of machine learning and the deep learning paradigm.

The role of E2F1-topoIIβ signaling in regulation of cell cycle exit and neuronal differentiation of human SH-SY5Y cells

This study aims to test the role of E2F1-topoIIβ signaling in neuronal differentiation of SH-SY5Y cells. With retinoic acid (RA) induction, a high percentage of cells were found to be arrested at the G₀/G₁ phase, with decreased levels of cyclinD1, CDK4, phosphorylation status of pRb and E2F1, in addition to an elevated level of p27. The cells were shown to differentiate into neuronal phenotypes characterized by highly expressed neuronal markers, MAP2 and enriched topoIIβ, and remarkable neurite outgrowth. Exogenously forced E2F1 expression with a specific E2F1 plasmid led to suppression of topoIIβ expression and disruption of the neuronal differentiation of SH-SY5Y cells. On further examination using the ChIP assay, we found that E2F1 bound directly to the promoter region of topoIIβ, and its binding ability was inversely correlated with topoIIβ expression in response to RA induction. Thus, our findings suggest that E2F1-topoIIβ signaling may play a role in regulation of cell cycle exit and neuronal differentiation.

Neural Stem Cell Dysfunction in Human Brain Disorders

Neural stem cells (NSCs) give rise to the entire nervous system. Animal models suggest that defects in NSC proliferation and differentiation contribute to several brain disorders (e.g., microcephaly, macrocephaly, autism, schizophrenia, and Huntington's disease). However, animal models of such diseases do not fully recapitulate all disease-related phenotypes because of substantial differences in brain development between rodents and humans. Therefore, additional human-based evidence is required to understand the mechanisms that are involved in the development of neurological diseases that result from human NSC (hNSC) dysfunction. Human-induced pluripotent stem cells provide a new model to investigate the contribution of hNSCs to various neurological pathologies. In this chapter, we review the role of hNSCs in both neurodevelopment- and neurodegeneration-related human brain pathologies, with an emphasis on recent evidence that has been obtained using embryonic stem cell- or induced pluripotent stem cell-derived hNSCs and progenitors.

Resistance to Cell Death and Its Modulation in Cancer Stem Cells

Accumulating evidence has demonstrated that human cancers arise from various tissues of origin that initiate from cancer stem cells (CSCs) or cancer-initiating cells. The extrinsic and intrinsic apoptotic pathways are dysregulated in CSCs, and these cells play crucial roles in tumor initiation, progression, cell death resistance, chemo- and radiotherapy resistance, and tumor recurrence. Understanding CSC-specific signaling proteins and pathways is necessary to identify specific therapeutic targets that may lead to the development of more efficient therapies selectively targeting CSCs. Several signaling pathways-including the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR), maternal embryonic leucine zipper kinase (MELK), NOTCH1, and Wnt/Β-catenin&and expression of the CSC markers CD133, CD24, CD44, Oct4, Sox2, Nanog, and ALDH1A1 maintain CSC properties. Studying such pathways may help to understand CSC biology and lead to the development of potential therapeutic interventions to render CSCs more sensitive to cell death triggered by chemotherapy and radiation therapy. Moreover, recent demonstrations of dedifferentiation of differentiated cancer cells into CSC-like cells have created significant complexity in the CSCs hypothesis. Therefore, any successful therapeutic agent or combination of drugs for cancer therapy must eliminate not only CSCs but differentiated cancer cells and the entire bulk of tumor cells. This review article expands on the CSC hypothesis and paradigm with respect to major signaling pathways and effectors that regulate CSC apoptosis resistance. Moreover, selective CSC apoptotic modulators and their therapeutic potential for making tumors more responsive to therapy are discussed. The use of novel therapies, including small-molecule inhibitors of specific proteins in signaling pathways that regulate stemness, proliferation and migration of CSCs, immunotherapy, and noncoding microRNAs may provide better means of treating CSCs.

ING5 activity in self-renewal of glioblastoma stem cells via calcium and follicle stimulating hormone pathways

Stem cell-like brain tumor initiating cells (BTICs) cause recurrence of glioblastomas, with BTIC 'stemness' affected by epigenetic mechanisms. The ING family of epigenetic regulators (ING1-5) function by targeting histone acetyltransferase (HAT) or histone deacetylase complexes to the H3K4me3 mark to alter histone acetylation and subsequently, gene expression. Here we find that ectopic expression of ING5, the targeting subunit of HBO1, MOZ and MORF HAT complexes increases expression of the Oct4, Olig2 and Nestin stem cell markers, promotes self-renewal, prevents lineage differentiation and increases stem cell pools in BTIC populations. This activity requires the plant homeodomain region of ING5 that interacts specifically with the H3K4me3 mark. ING5 also enhances PI3K/AKT and MEK/ERK activity to sustain self-renewal of BTICs over serial passage of stem cell-like spheres. ING5 exerts these effects by activating transcription of calcium channel and follicle stimulating hormone pathway genes. In silico analyses of The Cancer Genome Atlas data suggest that ING5 is a positive regulator of BTIC stemness, whose expression negatively correlates with patient prognosis, especially in the Proneural and Classical subtypes, and in tumors with low SOX2 expression. These data suggest that altering histone acetylation status and signaling pathways induced by ING5 may provide useful clinical strategies to target tumor resistance and recurrence in glioblastoma.

Znf179 induces differentiation and growth arrest of human primary glioblastoma multiforme in a p53-dependent cell cycle pathway

Malignant glioblastoma multiforme (GBM) is an aggressive brain tumor with strong local invasive growth and a poor prognosis. One probable way to manipulate GBM cells toward a less invasive status is to reprogram the most malignant GBM cells to a more differentiated and less oncogenic phenotype. Herein, we identified a novel role of a RING finger protein Znf179 in gliomagenesis. Znf179 overexpression induced differentiation of primary GBM cells, which were accompanied with elevated glial fibrillary acidic protein (GFAP) expression through up-regulating several cell-cycle-related factors, p53, p21, and p27, and allowed the cell-cycle arrest in the G₀/G₁ phase. In addition, Znf179 was highly correlated with the prognosis and survival rates of glioma patients. The expression levels of Znf179 was relatively lower in glioma patients compared to normal people, and glioma patients with lower expression levels of Znf179 mRNA had poorer prognosis and lower survival rates. In conclusion, we provide novel insight that Znf179 can reprogram GBM cells into a more-differentiated phenotype and prevent the progression of gliomas to a more-malignant state through p53-mediated cell-cycle signaling pathways. Understanding the molecular mechanism of Znf179 in gliomagenesis could help predict prognostic consequences, and targeting Znf179 could be a potential biomarker for glioma progression.

Immunohistochemical investigation of topoIIβ, H3K27me3 and JMJD3 expressions in medulloblastoma

Topoisomerase IIβ (topoIIβ) is a nuclear enzyme specifically expressed in neurons, and plays an important role in the development of the cerebellum. To date, the expression of topoIIβ protein in medulloblastoma (MB) has not been investigated. In this study, 16 MB specimens including 10 classical subtypes of MB and 6 desmoplastic subtypes of MB (DMB), along with 5 normal cerebellum samples, were obtained from clinics. With immunohistochemical staining, prominently expressed topoIIβ was seen in normal cerebellar tissues, while there was no or less pronounced staining in classical MB cells. Interestingly, on comparing topoIIβ expression in different regions of DMB samples, relatively high levels of topoIIβ were revealed within nodules composed of differentiated neurocytic cells, which are known to predict a favorable clinical outcome for MB. We also examined the expression of two epigenetic factors, H3K27me3 and JMJD3 in the different tissues. Very high levels of H3K27me3 were found in all MB samples, except the intranodules of DMB, where JMJD3 expression was more prominent. Furthermore, a negative correlation between topoIIβ and H3K27me3 in MB was revealed in this study. Thus, our data primarily indicate that topoIIβ can be used to estimate neuronal differentiation in MB, and may serve as a target for improving the survival rates for this condition. We speculate that H3K27me3 repression of topoIIβ at the transcriptional level may occur, although this needs to be verified using larger numbers of MB samples in future experiments.

DNA methylation analysis of paediatric low-grade astrocytomas identifies a tumour-specific hypomethylation signature in pilocytic astrocytomas

Low-grade gliomas (LGGs) account for about a third of all brain tumours in children. We conducted a detailed study of DNA methylation and gene expression to improve our understanding of the biology of pilocytic and diffuse astrocytomas. Pilocytic astrocytomas were found to have a distinctive signature at 315 CpG sites, of which 312 were hypomethylated and 3 were hypermethylated. Genomic analysis revealed that 182 of these sites are within annotated enhancers. The signature was not present in diffuse astrocytomas, or in published profiles of other brain tumours and normal brain tissue. The AP-1 transcription factor was predicted to bind within 200 bp of a subset of the 315 differentially methylated CpG sites; the AP-1 factors, FOS and FOSL1 were found to be up-regulated in pilocytic astrocytomas. We also analysed splice variants of the AP-1 target gene, CCND1, which encodes cell cycle regulator cyclin D1. CCND1a was found to be highly expressed in both pilocytic and diffuse astrocytomas, but diffuse astrocytomas have far higher expression of the oncogenic variant, CCND1b. These findings highlight novel genetic and epigenetic differences between pilocytic and diffuse astrocytoma, in addition to well-described alterations involving BRAF, MYB and FGFR1.

miR-340 suppresses glioblastoma multiforme

Deregulation of microRNAs (miRs) contributes to tumorigenesis. Down-regulation of miR-340 is observed in multiple types of cancers. However, the biological function of miR-340 in glioblastoma multiforme (GBM) remains largely unknown. In the present study, we demonstrated that expression of miR-340 was downregulated in both glioma cell lines and tissues. Survival of GBM patients with high levels of miR-340 was significantly extended in comparison to patients expressing low miR-340 levels. Biological functional experiments showed that the restoration of miR-340 dramatically inhibited glioma cell proliferation, induced cell-cycle arrest and apoptosis, suppressed cell motility and promoted autophagy and terminal differentiation. Mechanistic studies disclosed that, miR-340 over-expression suppressed several oncogenes including p-AKT, EZH2, EGFR, BMI1 and XIAP. Furthermore, ROCK1 was validated as a direct functional target miR-340 and silencing of ROCK1 phenocopied the anti-tumor effect of mR-340. Our findings indicate an important role of miR-340 as a glioma killer, and suggest a potential prognosis biomarker and therapeutic target for GBM.

MicroRNA-320a acts as a tumor suppressor by targeting BCR/ABL oncogene in chronic myeloid leukemia

Accumulating evidences demonstrated that the induction of epithelial-mesenchymal transition (EMT) and aberrant expression of microRNAs (miRNAs) are associated with tumorigenesis, tumor progression, metastasis and relapse in cancers, including chronic myeloid leukemia (CML). We found that miR-320a expression was reduced in K562 and in CML cancer stem cells. Moreover, we found that miR-320a inhibited K562 cell migration, invasion, proliferation and promoted apoptosis by targeting BCR/ABL oncogene. As an upstream regulator of BCR/ABL, miR-320a directly targets BCR/ABL. The enhanced expression of miR-320a inhibited the phosphorylation of PI3K, AKT and NF-κB; however, the expression of phosphorylated PI3K, AKT and NF-κB were restored by the overexpression of BCR/ABL. In K562, infected with miR-320a or transfected with SiBCR/ABL, the protein levels of fibronectin, vimentin, and N-cadherin were decreased, but the expression of E-cadherin was increased. The expression of mesenchymal markers in miR-320a-expressing cells was restored to normal levels by the restoration of BCR/ABL expression. Generally speaking, miR-320a acts as a novel tumor suppressor gene in CML and miR-320a can decrease migratory, invasive, proliferative and apoptotic behaviors, as well as CML EMT, by attenuating the expression of BCR/ABL oncogene.

Peroxynitrite-mediated glyoxalase I epigenetic inhibition drives apoptosis in airway epithelial cells exposed to crystalline silica via a novel mechanism involving argpyrimidine-modified Hsp70, JNK, and NF-κB

Glyoxalase I (Glo1) is a cellular defense enzyme involved in the detoxification of methylglyoxal (MG), a cytotoxic by-product of glycolysis, and MG-derived advanced glycation end products (AGEs). Argpyrimidine (AP), one of the major AGEs coming from MG modification of protein arginines, is a proapoptotic agent. Crystalline silica is a well-known occupational health hazard, responsible for a relevant number of pulmonary diseases. Exposure of cells to crystalline silica results in a number of complex biological responses, including apoptosis. The present study was aimed at investigating whether, and through which mechanism, Glo1 was involved in Min-U-Sil 5 crystalline silica-induced apoptosis. Apoptosis, by TdT-mediated dUTP nick-end labeling assay, and transcript and protein levels or enzymatic activity, by quantitative real-time PCR, Western blot, and spectrophotometric methods, respectively, were evaluated in human bronchial BEAS-2B cells exposed or not (control) to crystalline silica and also in experiments with appropriate inhibitors. Reactive oxygen species were evaluated by coumarin-7-boronic acid or Amplex red hydrogen peroxide/peroxidase methods for peroxynitrite (ONOO(-)) or hydrogen peroxide (H2O2) measurements, respectively. Our results showed that Min-U-Sil 5 crystalline silica induced a dramatic ONOO(-)-mediated inhibition of Glo1, leading to AP-modified Hsp70 protein accumulation that, in a mechanism involving JNK and NF-κB, triggered an apoptotic mitochondrial pathway. Inhibition of Glo1 occurred at both functional and transcriptional levels, the latter occurring via ERK1/2 MAPK and miRNA 101 involvement. Taken together, our data demonstrate that Glo1 is involved in the Min-U-Sil 5 crystalline silica-induced BEAS-2B cell mitochondrial apoptotic pathway via a novel mechanism involving Hsp70, JNK, and NF-κB. Because maintenance of an intact respiratory epithelium is a critically important determinant of normal respiratory function, the knowledge of the mechanisms underlying its disruption may provide insight into the genesis, and possibly the prevention, of a number of pathological conditions commonly occurring in silica dust occupational exposure.

Proteomic analysis of human sonic hedgehog (SHH) medulloblastoma stem-like cells

First proteomic characterization of sonic hedgehog human medulloblastoma stem-like cells.