Glioma Differentiation Research Articles

Differentiation between recurrent gliomas and radiation necrosis using arterial spin labeling perfusion imaging.

Arterial spin labeling (ASL) magnetic resonance (MR) perfusion imaging has been proposed as an effective method to measure brain tumor perfusion. The aim of the present study was to evaluate the utility of this technique in the differentiation of recurrent gliomas from radiation necrosis. Twenty-one patients with surgically treated primary gliomas, including 16 cases of recurrent glioma and 5 of radiation necrosis were examined using 3.0T MR imaging (MRI). ASL and dynamic susceptibility contrast-weighted (DSC) perfusion MRI scans were performed. Maps of normalized cerebral blood flow (CBF) in ASL imaging and cerebral blood volume (CBV) in DSC imaging were computed and analyzed in the regions of interest. In cases of glioma recurrence, the normalized ASL-CBF ratio (4.45±2.72) was higher than that in cases of radiation injury (1.22±0.61) (P<0.01). The normalized DSC-relative CBV ratio was also significantly higher in glioma recurrence (3.38±2.08) than it was in radiation injury (1.09±0.55) (P<0.05). A close linear correlation was found between the ASL and DSC MRI techniques (linear regression coefficient, R=0.85; P=0.005) in the differentiation of recurrent glioma from radiation injury. The results indicate that ASL perfusion is an accurate method of distinguishing between glioma recurrence and radiation necrosis.

Overexpression of ubiquitin-specific protease 2a (USP2a) and nuclear factor erythroid 2-related factor 2 (Nrf2) in human gliomas

BackgroundGliomas are among the most frequent adult primary brain tumors. Recent studies have shown that there are novel opportunities for developing therapeutics by targeting the differentiation and self-renewal features of glioma. ObjectiveThe aim of this study was to evaluate the expression levels of USP2a an Nrf2 in patients with glioma and their association with prognosis of gliomas that was detected with immunohistochemical staining. MethodsIn this study, 40 patient's tissue samples with primary gliomas were collected between January 2009 and December 2013. MRI of patients was done before and within 24h after surgery. USP2a and Nrf2 expression levels were examined by immunohistochemistry. Data were analyzed using the SPSS 16.0, X2 test, log-rank test and Kaplan-Meier method. ResultsImmunohistochemistry indicated that USP2a expression was increased in glioma cells than normal brain tissues. The increased USP2a staining was markedly correlated with advanced tumor grade (P=0.02) and age (P=0.016). Our result showed that Nrf2 expression was significantly higher in glioma cells as compared to normal brain tissues. The high expression level of Nrf2 was markedly linked to age (P=0.007), and tumor grade (P=0.03). Kaplan-Meier survival and log-rank analysis indicated that patients with low expression of USP2a had longer overall survival than those with high levels (log-rank test P<0.001). Moreover, patients with high Nrf2 expression had shorter overall survival than those with low levels (log-rank test P<0.001). In the univariate analysis, the high expression of Nrf2 and USP2a (P=0.004; P=0.006), age (P=0.025), and tumor grade (P=0.001) were correlated with poor survival. Multivariate Cox proportional hazards model indicated that, high Nrf2 and USP2a staining (P=0.001; P=0.003), advanced tumor grade (P=0.01) and age (P=0.033) were independent predictor of overall survival. ConclusionIn summary, the result of this study showed USP2a and Nrf2 may be as prognostic marker in patients with gliomas.

Lipid and metabolite profiles of human brain tumors by desorption electrospray ionization-MS

Examination of tissue sections using desorption electrospray ionization (DESI)-MS revealed phospholipid-derived signals that differ between gray matter, white matter, gliomas, meningiomas, and pituitary tumors, allowing their ready discrimination by multivariate statistics. A set of lower mass signals, some corresponding to oncometabolites, including 2-hydroxyglutaric acid and N-acetyl-aspartic acid, was also observed in the DESI mass spectra, and these data further assisted in discrimination between brain parenchyma and gliomas. The combined information from the lipid and metabolite MS profiles recorded by DESI-MS and explored using multivariate statistics allowed successful differentiation of gray matter (n = 223), white matter (n = 66), gliomas (n = 158), meningiomas (n = 111), and pituitary tumors (n = 154) from 58 patients. A linear discriminant model used to distinguish brain parenchyma and gliomas yielded an overall sensitivity of 97.4% and a specificity of 98.5%. Furthermore, a discriminant model was created for tumor types (i.e., glioma, meningioma, and pituitary), which were discriminated with an overall sensitivity of 99.4% and a specificity of 99.7%. Unsupervised multivariate statistics were used to explore the chemical differences between anatomical regions of brain parenchyma and secondary infiltration. Infiltration of gliomas into normal tissue can be detected by DESI-MS. One hurdle to implementation of DESI-MS intraoperatively is the need for tissue freezing and sectioning, which we address by analyzing smeared biopsy tissue. Tissue smears are shown to give the same chemical information as tissue sections, eliminating the need for sectioning before MS analysis. These results lay the foundation for implementation of intraoperative DESI-MS evaluation of tissue smears for rapid diagnosis.

Genetic and Epigenetic Mechanisms Promote IDH1-Mutant Glioma Progression

Abstract Genetic and epigenetic changes drive cell growth and inhibit differentiation of IDH1-mutant glioma.

Abscisic-acid-induced cellular apoptosis and differentiation in glioma via the retinoid acid signaling pathway.

Retinoid acid (RA) plays critical roles in regulating differentiation and apoptosis in a variety of cancer cells. Abscisic acid (ABA) and RA are direct derivatives of carotenoids and share structural similarities. Here we proposed that ABA may also play a role in cellular differentiation and apoptosis by sharing a similar signaling pathway with RA that may be involved in glioma pathogenesis. We reported for the first time that the ABA levels were twofold higher in low-grade gliomas compared with high-grade gliomas. In glioma tissues, there was a positive correlation between the ABA levels and the transcription of cellular retinoic acid-binding protein 2 (CRABP2) and a negative correlation between the ABA levels and transcription of fatty acid-binding protein 5 (FABP5). ABA treatment induced a significant increase in the expression of CRABP2 and a decrease in the expression of peroxisome proliferator-activated receptor (PPAR) in glioblastoma cells. Remarkably, both cellular apoptosis and differentiation were increased in the glioblastoma cells after ABA treatment. ABA-induced cellular apoptosis and differentiation were significantly reduced by selectively silencing RAR-α, while RAR-α overexpression exaggerated the ABA-induced effects. These results suggest that ABA may play a role in the pathogenesis of glioma by promoting cellular apoptosis and differentiation through the RA signaling pathway.

RACK1 affects glioma cell growth and differentiation through the CNTN2-mediated RTK/Ras/MAPK pathway

Receptor for activated C kinase 1 (RACK1) and contactin-2 (CNTN2) are known to be abnormally expressed in gliomas; however, the association between RACK1 and CNTN2, and the effects of RACK1 and CNTN2 on glioma cell differentiation and the related molecular mechanisms remain largely unknown. The present study aimed to investigate the interaction between RACK1 and CNTN2, and to examine whether RACK1/CNTN2/receptor tyrosine kinase (RTK)/Ras/mitogen-activated protein kinase (MAPK) axis plays a role in glioma growth and differentiation. The results from western blot analysis revealed that the protein expression levels of RACK1 and CNTN2 were higher in high‑grade glioma tissues and cells, and lower in low-grade glioma tissues and cells. A co-immunoprecipitation assay demonstrated that RACK1 interacts with CNTN2, and RACK1 upregulated the expression of CNTN2. Gain-of‑function and loss-of‑function experiments indicated that both RACK1 and CNTN2 promoted glioma cell proliferation, inhibited glioma cell differentiation and activated the RTK/Ras/MAPK pathway. However, the effects of RACK1 on glioma cell proliferation, differentiation and the activation of the RTK/Ras/MAPK signaling pathway were abolished by the knockdown of CNTN2 using siRNA. In Therefore, the findings of this study firstly demonstrate that RACK1 interacts with CNTN2, and that the effects of RACK1 on glioma cell growth and differentiation are mediated by CNTN2. The RACK1/CNTN2/RTK/Ras/MAPK axis exists in glioma cells, and it may be a potential therapeutic target in gliomas.

Study on Relationship between Differentiation and Autophagy of Glioma Stem/Progenitor Cells

Study on Relationship between Differentiation and Autophagy of Glioma Stem/Progenitor Cells

Fractal analysis: fractal dimension and lacunarity from MR images for differentiating the grades of glioma

Glioma, the heterogeneous tumors originating from glial cells, generally exhibit varied grades and are difficult to differentiate using conventional MR imaging techniques. When this differentiation is crucial in the disease prognosis and treatment, even the advanced MR imaging techniques fail to provide a higher discriminative power for the differentiation of malignant tumor from benign ones. A powerful image processing technique applied to the imaging techniques is expected to provide a better differentiation. The present study focuses on the fractal analysis of fluid attenuation inversion recovery MR images, for the differentiation of glioma. For this, we have considered the most important parameters of fractal analysis, fractal dimension and lacunarity. While fractal analysis assesses the malignancy and complexity of a fractal object, lacunarity gives an indication on the empty space and the degree of inhomogeneity in the fractal objects. Box counting method with the preprocessing steps namely binarization, dilation and outlining was used to obtain the fractal dimension and lacunarity in glioma. Statistical analysis such as one-way analysis of variance and receiver operating characteristic (ROC) curve analysis helped to compare the mean and to find discriminative sensitivity of the results. It was found that the lacunarity of low and high grade gliomas vary significantly. ROC curve analysis between low and high grade glioma for fractal dimension and lacunarity yielded 70.3% sensitivity and 66.7% specificity and 70.3% sensitivity and 88.9% specificity, respectively. The study observes that fractal dimension and lacunarity increases with an increase in the grade of glioma and lacunarity is helpful in identifying most malignant grades.

Differentiation of high-grade and low-grade diffuse gliomas by intravoxel incoherent motion MR imaging.

Our aim was to assess the diagnostic performance of intravoxel incoherent motion (IVIM) MR imaging for differentiating high-grade gliomas (HGGs) from low-grade gliomas (LGGs). Forty-five patients with diffuse glioma (age 50.9 ± 20.4 y; 26 males, 19 females) were assessed with IVIM imaging using 13 b-values (0-1000 s/mm(2)) at 3T. The perfusion fraction (f), true diffusion coefficient (D), and pseudo-diffusion coefficient (D*) were calculated by fitting the bi-exponential model. The apparent diffusion coefficient (ADC) was obtained with 2 b-values (0 and 1000 s/mm(2)). Relative cerebral blood volume was measured by the dynamic susceptibility contrast method. Two observers independently measured D, ADC, D*, and f, and these measurements were compared between the LGG group (n = 16) and the HGG group (n = 29). Both D (1.26 ± 0.37 mm(2)/s in LGG, 0.94 ± 0.19 mm(2)/s in HGG; P < .001) and ADC (1.28 ± 0.35 mm(2)/s in LGG, 1.03 ± 0.19 mm(2)/s in HGG; P < .01) were lower in the HGG group. D was lower than ADC in the LGG (P < .05) and HGG groups (P < .0001). D* was not different between the groups. The f-values were significantly larger in HGG (17.5 ± 6.3%) than in LGG (5.8 ± 3.8%; P < .0001) and correlated with relative cerebral blood volume (r = 0.85; P < .0001). Receiver operating characteristic analyses showed areas under curve of 0.95 with f, 0.78 with D, 0.73 with ADC, and 0.60 with D*. IVIM imaging is useful in differentiating HGGs from LGGs.

Grading of Gliomas by Using Monoexponential, Biexponential, and Stretched Exponential Diffusion-weighted MR Imaging and Diffusion Kurtosis MR Imaging.

To quantitatively compare the potential of various diffusion parameters obtained from monoexponential, biexponential, and stretched exponential diffusion-weighted imaging models and diffusion kurtosis imaging in the grading of gliomas. This study was approved by the local ethics committee, and written informed consent was obtained from all subjects. Both diffusion-weighted imaging and diffusion kurtosis imaging were performed in 69 patients with pathologically proven gliomas by using a 3-T magnetic resonance (MR) imaging unit. An isotropic apparent diffusion coefficient (ADC), true ADC, pseudo-ADC, and perfusion fraction were calculated from diffusion-weighted images by using a biexponential model. A water molecular diffusion heterogeneity index and distributed diffusion coefficient were calculated from diffusion-weighted images by using a stretched exponential model. Mean diffusivity, fractional anisotropy, and mean kurtosis were calculated from diffusion kurtosis images. All values were compared between high-grade and low-grade gliomas by using a Mann-Whitney U test. Receiver operating characteristic and Spearman rank correlation analysis were used for statistical evaluations. ADC, true ADC, perfusion fraction, water molecular diffusion heterogeneity index, distributed diffusion coefficient, and mean diffusivity values were significantly lower in high-grade gliomas than in low-grade gliomas (U = 109, 56, 129, 6, 206, and 229, respectively; P < .05). Pseudo-ADC and mean kurtosis values were significantly higher in high-grade gliomas than in low-grade gliomas (U = 98 and 8, respectively; P < .05). Both water molecular diffusion heterogeneity index (area under the receiver operating characteristic curve [AUC] = 0.993) and mean kurtosis (AUC = 0.991) had significantly greater AUC values than ADC (AUC = 0.866), mean diffusivity (AUC = 0.722), and fractional anisotropy (AUC = 0.500) in the differentiation of low-grade and high-grade gliomas (P < .05). Water molecular diffusion heterogeneity index and mean kurtosis values may provide additional information and improve the grading of gliomas compared with conventional diffusion parameters.

Long Non-Coding RNAs: The Key Players in Glioma Pathogenesis.

Long non-coding RNAs (LncRNAs) represent a novel class of RNAs with no functional protein-coding ability, yet it has become increasingly clear that interactions between lncRNAs with other molecules are responsible for important gene regulatory functions in various contexts. Given their relatively high expressions in the brain, lncRNAs are now thought to play important roles in normal brain development as well as diverse disease processes including gliomagenesis. Intriguingly, certain lncRNAs are closely associated with the initiation, differentiation, progression, recurrence and stem-like characteristics in glioma, and may therefore be exploited for the purposes of sub-classification, diagnosis and prognosis. LncRNAs may also serve as potential therapeutic targets as well as a novel biomarkers in the treatment of glioma. In this article, the functional aspects of lncRNAs, particularly within the central nervous system (CNS), will be briefly discussed, followed by highlights of the important roles of lncRNAs in mediating critical steps during glioma development. In addition, the key lncRNA players and their possible mechanistic pathways associated with gliomagenesis will be addressed.

Mathematical modeling reveals a critical role for cyclin D1 dynamics in phenotype switching during glioma differentiation

Glioma differentiation therapy is a novel modality to increase anti-glioma effects using specific drugs to induce glioma cell differentiation to glia-like cells. However, the molecular mechanisms underlying glioma differentiation remain poorly understood. In this study, we built an experiment-integrated mathematical model for glioma differentiation signaling pathways. Our modeling and experimental analysis revealed that a “one-way-switch” bifurcation of cyclin D1 dynamics was critical for controlling the phenotypic transition of glioma cells. We also quantitatively evaluated drug combinations toward a synergistic therapeutic effect. These results provide insights into the molecular mechanisms underlying glioma differentiation and implications for the design of novel therapeutic targets in anti-cancer therapy.

Analysis of IDH1-R132 mutation, BRAF V600 mutation and KIAA1549-BRAF fusion transcript status in central nervous system tumors supports pediatric tumor classification.

Gliomas are the leading cause of cancer-related morbidity in children and comprise a clinical, histological and molecular heterogenous group of CNS tumors. Appropriate treatment of these tumors relies on correct classification into tumor types and malignancy grades. We examined 170 (0-18 years) pediatric and 131 (19-35 years) young adult brain tumors including pilocytic astrocytomas (PAs), pilomyxoid astrocytomas (PMAs), diffuse astrocytomas (DAs), gangliogliomas, dysembryoplastic neuroepithelial tumors (DNTs) and pleomorphic xanthoastrocytomas (PXAs) for IDH1 and BRAF mutation/BRAF fusion gene status. The obtained data were compared to results in 464 (<35 years) adult brain tumors. In 32 tumors with an oligodendroglial or mixed glioma differentiation, additionally the LOH1p/19q status was determined. By combining immunohistochemistry and molecular methods, IDH1/2 mutations were observed in 6 pediatric, 35 young adult and 43 adult tumors of the astrocytic/oligodendroglial lineage. BRAF V600E mutations (20 pediatric, 7 young adults and 2 adults) were found mostly in gangliogliomas, PXAs, few astrocytomas and few DNTs. Except for one DA case, BRAF fusions (35 pediatric, 8 young adults and 2 adults) were restricted to PA and PMA and associated with age and infratentorial location. All mutations were mutually exclusive and always present in the primary tumor. Two-thirds of all pediatric samples harbored one of the three examined mutations. Combination of IDH1-R132, BRAF V600 and KIAA1549-BRAF fusion analysis is therefore a useful tool to increase diagnostic accuracy in pediatric gliomas.

Transcriptional upregulation of microtubule-associated protein 2 is involved in the protein kinase A-induced decrease in the invasiveness of glioma cells.

Malignant glioma is the most lethal primary tumor of the central nervous system, with notable cell invasion causing significant recurrence. Suppression of glioma invasion is very important for improving clinical outcomes. Drugs that directly disrupt the cytoskeleton have been developed for this purpose; however, drug resistance and unsatisfactory selectivity have limited their clinical use. Previously, we reported that protein kinase A (PKA, also known as cyclic-AMP dependent protein kinase) activation induced the differentiation of glioma cells. We used several small molecular inhibitors and RNA interference, combined with wound healing assays, Matrigel transwell assay, and microscopic observation, to determine whether activation of the PKA pathway could inhibit the invasion of human glioma cells. Activation of PKA decreased the invasion of glioma cells. The mechanism operated via transcriptional upregulation of microtubule-associated protein 2 (MAP2), which was activated by the PKA pathway and led to ossification of microtubule dynamics via polymerization of tubulin. This resulted in morphological changes and a reduction in glioma cell invasion. Furthermore, chromosome immunoprecipitation and quantitative real-time polymerase chain reaction showed that signal transducer and activator of transcription 3 (STAT3) is involved in the transcriptional upregulation of MAP2. Our findings suggested that PKA may represent a potential target for anti-invasion glioma therapy and that the downstream modulators (eg, STAT3/MAP2) partially mediate the effects of PKA.

Differential expression of insulin-like growth factor binding protein- 3 in the different grades of glioma and its correlation with malignancy of glial tumors

Objective To explore the differential expression of insulin- like growth factor- binding protein- 3(IGFBP- 3)in normal brain tissue and different grades of gliomas,and its corralation with the differentiation and malignance of gliomas. Methods By real- time quantitative polymerase chain reaction (Real- time PCR)and immunohistochemical staining methods, the expression of IGFBP- 3 was detected in 11 cases of grade-Ⅱglioma tissue samples, 14 cases of grade-Ⅲglioma tissue specimens, 9 cases of grade-Ⅳgrade glioma tissue samples,and 16 specimens of normal brain tissue. Results The average optical density values of IGFBP- 3 in normal brain tissue specimens and the specimens of grade-Ⅱ,-Ⅲ,-Ⅳgliomas were 1.082 2±0.334 7, 1.535 0±0.226 7, 4.383 1±0.521 8, and 5.094 1±0.652 5 respectively.Single factor analysis of variance(One- way ANOVA)and LSD, SNK- t analysis comparison showed there was significant difference in the expression of IGFBP- 3 between human gliomas and normal brain tissue(P< 0.05), and between grade-Ⅱand grade-Ⅲor grade-Ⅳgliomas(P< 0.05).By immunohistochemical staining methods,the positive expression rate of IGFBP- 3 was 20.0% in normal brain tissue specimens, which was significantly lower than in grade-Ⅱ(33.3%),-Ⅲ(57.1%), and-Ⅳ(80.0%)glimas(P<0.05 for all).There was no significant difference among different grades of gliomas. Conclusion The expression of IGFBP- 3 was significantly reduced in gliomas,and closely related with disease progression. Key words: Glioma; Insulin- like growth factor binding protein- 3; Promote apoptosis

Glucose-corrected standardized uptake value in the differentiation of high-grade glioma versus post-treatment changes.

BackgroundStandardized uptake values (SUVs) of fluorine-18 fluorodeoxyglucose PET (18F-FDG PET) are used widely to differentiate residual or recurrent high-grade gliomas from post-treatment changes in patients with brain tumors. The aim of this study is to assess the accuracy of SUV corrected by blood glucose level (SUVgluc) compared with various quantitative methods in this role.Materials and methodsIn 55 patients with dynamic 18F-FDG PET scans, there were 97 glioma lesions: glioblastoma (n=60), grade III gliomas (n=22), grade III or IV gliomas (n=6), grade I/II (n=7), and prebiopsy lesions (n=2). The final actual diagnosis was made on the basis of pathology (n=33) and clinical outcome (n=64). Dynamic 18F-FDG PET scans were processed to generate parametric images of SUVgluc, SUVmax, and glucose metabolic rate (GMR). Lesion to cerebellum ratios (SUVRc) and contralateral white matter ratios (SUVRw) were also measured. The SUVgluc was calculated as SUVmax×blood glucose level/100.ResultsUsing the thresholds of SUVmax>4.6, SUVRc>0.9, SUVRw>1.8, SUVgluc>4.3, and GMR>12.2 μmol/min/100 g to represent positivity for viable tumors, the accuracies were the same for the SUVgluc and SUVRw (80%) and were higher than the conventional SUVmax (72%). The area under the receiver operating characteristic curve for the SUVgluc (0.8933) was better than that for the SUVmax (0.8266) (P<0.01) and was similar to those of the GMR (0.8622), SUVRc (0.8606), and SUVRw (0.8981).ConclusionThese results suggest that SUVgluc may aid in the differentiation of residual or recurrent high-grade tumor from post-treatment changes in patients with abnormal blood glucose levels. The simplicity of the SUVgluc avoids the complexity of kinetic analysis or the requirement of a reference tissue.

BI-03 * DLX HOMEOBOX GENES REGULATE NEURONAL VS OLIGODENDROGLIAL CELL FATE DECISIONS: POTENTIAL RELEVANCE TO PEDIATRIC GLIONEURONAL TUMORS AND HIGH GRADE GLIOMAS

BACKGROUND: Pediatric high grade gliomas (pHGG) are localized to different neuroanatomic compartments with significant differences in their gene expression profiles. In Histone H3.3 G34V/R mutants, DLX2 homeobox gene expression is increased with a corresponding decrease in myelin transcription factor (MYT1) expression. DLX genes are necessary for tangential migration and differentiation of inhibitory interneurons during CNS development. Neural progenitors derived from DLX1/DLX2 double knockout (DKO) mice transplanted into a wild-type forebrain differentiate into oligodendrocytes, providing support for the DLX homeobox genes in neuronal-glial cell fate decisions. METHODS: Chromatin immunoprecipitation (ChIP) assays using a DLX2 antibody were followed by qPCR. ChIP-reChIP assays were performed using antibodies that recognize specific histone modifications. Electrophoretic mobility shift assays (EMSA) were performed using recombinant DLX2 protein and oligonucleotide probes from ChIP-specified promoter regions. Reporter gene assays provided functional assessment of protein-DNA interactions in vitro. Target gene expression was assessed comparing wild-type (WT) and DLX1/DLX2 DKO tissues. RESULTS: Homeodomain binding sites were localized to the promoters of Olig2, Myt1, Nkx2.2 and others in silico. ChIP assays confirmed promoter occupancy by DLX2. ChIPseq experiments are underway. EMSA studies demonstrated specific DLX2-promoter complexes. Luciferase assays showed repression of Olig2 and Nkx2.2 reporter gene expression, consistent with co-occupancy of H3K27me3 in WT and increased target gene expression in DLX1/DLX2 DKO embryonic tissues. We also demonstrated DLX2 expression in a cohort of gangliogliomas. CONCLUSIONS: Our results support a role for DLX transcription factors in controlling neural progenitor specification by activating GABAergic and inhibiting oligodendroglial cell fates through transcriptional repression of a suite of genes required for oligodendrocyte differentiation. Understanding how pHGG and glioneuronal tumors co-opt these neurodevelopmental programs will lead to novel pharmacologic approaches that promote glioma differentiation.

ET-08 * DEMETHYLATING THERAPY INDUCES DIFFERENTATION AND THERAPEUTIC RESPONSE IN IDH1 MUTANT MALIGNANT GLIOMAS

Isocitrate Dehydrogenase 1 (IDH1) mutations are frequent in progressive GBMs and the grade II and III gliomas from which they arise. The mutant IDH1 enzyme pathologically produces 2-hydroxyglutarate (2-HG) that metabolically inhibits α-ketogluterate dependent histone and DNA demethylases. This results in abnormal hypermethylation of genomic DNA that subsequently suppress cellular differentiation. We have investigated the use of the FDA approved drug, 5-azacytidine, and have shown it to be an effective agent in two preclinical models of IDH1 mutant glioma. To accurately model the IDH1 mutation oncogenic process, we developed a patient derived IDH1 mutant anaplastic astrocytoma model which produces 2-HG and shows a hypermethylated genome. Using this genetically and molecularly accurate model we have demonstrated the preclinical efficacy and mechanism of action of the FDA approved demethylating drug 5-azacytidine in vivo. Long term administration of 5-azacytidine resulted in reduction of DNA methylation of promoter loci, induction of glial differentiation, reduction of cell proliferation and significantly reduced tumor growth. Nearly complete tumor regression was observed by 14 weeks, resulting in a sustainable response and significant survival benefit. The sequence of events leading to a therapeutic response in IDH1 mutant gliomas appear to be first, inactivation of DNMT1, Loci specific genome demethylation, key alterations in the gene expression pattern, cellular differentiation followed by growth arrest. Overall, our goal is to find the most effective combination strategy for forcing differentiation in IDH1 mutant gliomas. It is based on targeting the epigenetic mechanism of transformation specific to the tumor, and xenograft models that have the native mutation. In is hoped that the results from this work will allow a better clinical trial design specific for IDH1 mutant glioma, as well as key biomarkers for therapeutic response.

Circulating endothelial progenitor cells are involved in VEGFR-2-related endothelial differentiation in glioma.

Endothelial progenitor cells (EPCs) play important roles in maintaining endothelial integrity and tumor vascularization. However, the differentiation of EPCs in the neoangiogenesis of gliomas has not yet been fully elucidated. The purpose in this study was to investigate the profile of EPC differentiation in rat C6 glioma using magnetic resonance imaging (MRI), a non-invasive monitoring assay. To achieve this goal, we isolated EPCs from rat bone marrow and identified them by detecting CD34, CD133, and VEGFR-2, the markers of EPCs. Coexpression of Ac-LDL and UEA-1 in EPCs was also determined. To dynamically monitor the migration of circulating cells, the EPCs were labeled with ultrasmall superparamagnetic iron oxide(USPIO) and injected by tail vein into rats bearing C6 glioma. MRI was performed at 24, 48, and 96h after injection. The distribution and differentiation of EPCs were confirmed by histology. We found that the USPIO-labeled EPCs appeared at the tumor periphery where a large number of CD105-positive cells appeared at 24h after injection by using MRI scanning. Ninety-six hours after injection, immunohistochemistry and Prussian blue staining were used to observe the labeled EPCs in the tumor tissue. We found that many of the labeled EPCs were overlapped with VEGFR-2-positive endothelial cells, but not CD105- or CD34-positive cells. These results suggest that EPCs can cross the blood-brain barrier from peripheral blood and home to tumors, where they differentiate into endothelial cells, including VEGFR-2-positive endothelial cells. MRI is a useful method for dynamically tracking the migration of USPIO-labeled EPCs.

Fast spectroscopic multiple analysis (FASMA) for brain tumor classification: a clinical decision support system utilizing multi-parametric 3T MR data.

A clinical decision support system (CDSS) for brain tumor classification can be used to assist in the diagnosis and grading of brain tumors. A Fast Spectroscopic Multiple Analysis (FASMA) system that uses combinations of multiparametric MRI data sets was developed as a CDSS for brain tumor classification. MRI metabolic ratios and spectra, from long and short TE, respectively, as well as diffusion and perfusion data were acquired from the intratumoral and peritumoral area of 126 patients with untreated intracranial tumors. These data were categorized based on the pathology, and different machine learning methods were evaluated regarding their classification performance for glioma grading and differentiation of infiltrating versus non-infiltrating lesions. Additional databases were embedded to the system, including updated literature values of the related MR parameters and typical tumor characteristics (imaging and histological), for further comparisons. Custom Graphical User Interface (GUI) layouts were developed to facilitate classification of the unknown cases based on the user's available MR data. The highest classification performance was achieved with a support vector machine (SVM) using the combination of all MR features. FASMA correctly classified 89 and 79% in the intratumoral and peritumoral area, respectively, for cases from an independent test set. FASMA produced the correct diagnosis, even in the misclassified cases, since discrimination between infiltrative versus non-infiltrative cases was possible. FASMA is a prototype CDSS, which integrates complex quantitative MR data for brain tumor characterization. FASMA was developed as a diagnostic assistant that provides fast analysis, representation and classification for a set of MR parameters. This software may serve as a teaching tool on advanced MRI techniques, as it incorporates additional information regarding typical tumor characteristics derived from the literature.