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PG545 does not pass the blood-brain barrier (BBB), reduces flank tumor weight in mice, and causes no weight loss

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Curative therapy for medulloblastoma and other pediatric embryonal brain tumors has improved, but the outcome still remains poor and current treatment causes long-term complications. Malignant brain tumors infiltrate the healthy brain tissue and, thus despite resection, cells that have already migrated cause rapid tumor regrowth. Heparan sulfate proteoglycans (HSPG), major components of the extracellular matrix (ECM), modulate the activities of a variety of proteins. The major enzyme that degrades HS, heparanase (HPSE), is an important regulator of the ECM. Here, we report that the levels of HPSE in pediatric brain tumors are higher than in healthy brain tissue and that treatment of pediatric brain tumor cells with HPSE stimulated their growth. In addition, the latent, 65 kDa form of HPSE (that requires intracellular enzymatic processing for activation) enhanced cell viability and rapidly activated the ERK and AKT signaling pathways, before enzymatically active HPSE was detected. The HPSE inhibitor PG545 efficiently killed pediatric brain tumor cells, but not normal human astrocytes, and this compound also reduced tumor cell invasion in vitro and potently reduced the size of flank tumors in vivo. Our findings indicate that HPSE in malignant brain tumors affects both the tumor cells themselves and their ECM. In conclusion, HPSE plays a substantial role in childhood brain tumors, by contributing to tumor aggressiveness and thereby represents a potential therapeutic target. Mol Cancer Ther; 16(8); 1705–16. ©2017 AACR.

The identity of the glioblastoma (GBM) cell of origin and its contributions to disease progression and treatment response remain largely unknown. We have analyzed how the phenotypic state of the initially transformed cell affects mouse GBM development and essential GBM cell (GC) properties. We find that GBM induced in neural stem-cell-like glial fibrillary acidic protein (GFAP)-expressing cells in the subventricular zone of adult mice shows accelerated tumor development and produces more malignant GCs (mGC1GFAP) that are less resistant to cancer drugs, compared with those originating from more differentiated nestin- (mGC2NES) or 2,′3′-cyclic nucleotide 3′-phosphodiesterase (mGC3CNP)-expressing cells. Transcriptome analysis of mouse GCs identified a 196 mouse cell origin (MCO) gene signature that was used to partition 61 patient-derived GC lines. Human GC lines that clustered with the mGC1GFAP cells were also significantly more self-renewing, tumorigenic, and sensitive to cancer drugs compared with those that clustered with mouse GCs of more differentiated origin.

Curative therapy for medulloblastoma and other pediatric embryonal brain tumors has improved, but the outcome still remains poor and current treatment causes long-term complications. Malignant brain tumors infiltrate the healthy brain tissue and, thus despite resection, cells that have already migrated cause rapid tumor regrowth. Heparan sulfate proteoglycans (HSPG), major components of the extracellular matrix (ECM), modulate the activities of a variety of proteins. The major enzyme that degrades HS, heparanase (HPSE), is an important regulator of the ECM. Here, we report that the levels of HPSE in pediatric brain tumors are higher than in healthy brain tissue and that treatment of pediatric brain tumor cells with HPSE stimulated their growth. In addition, the latent, 65 kDa form of HPSE (that requires intracellular enzymatic processing for activation) enhanced cell viability and rapidly activated the ERK and AKT signaling pathways, before enzymatically active HPSE was detected. The HPSE inhibitor PG545 efficiently killed pediatric brain tumor cells, but not normal human astrocytes, and this compound also reduced tumor cell invasion

Glioblastoma are aggressive astrocytic brain tumours characterized by microvascular proliferation and an abnormal vasculature, giving rise to brain oedema and increased patient morbidity. Here, we ...

Glioblastomas are aggressive astrocytomas characterized by endothelial cell proliferation and abnormal vasculature, which can cause brain edema and increase patient morbidity. We identified the heparin-binding cytokine pleiotrophin as a driver of vascular abnormalization in glioma. Pleiotrophin abundance was greater in high-grade human astrocytomas and correlated with poor survival. Anaplastic lymphoma kinase (ALK), which is a receptor that is activated by pleiotrophin, was present in mural cells associated with abnormal vessels. Orthotopically implanted gliomas formed from GL261 cells that were engineered to produce pleiotrophin showed increased microvessel density and enhanced tumor growth compared with gliomas formed from control GL261 cells. The survival of mice with pleiotrophin-producing gliomas was shorter than that of mice with gliomas that did not produce pleiotrophin. Vessels in pleiotrophin-producing gliomas were poorly perfused and abnormal, a phenotype that was associated with increased deposition of vascular endothelial growth factor (VEGF) in direct proximity to the vasculature. The growth of pleiotrophin-producing GL261 gliomas was inhibited by treatment with the ALK inhibitor crizotinib, the ALK inhibitor ceritinib, or the VEGF receptor inhibitor cediranib, whereas control GL261 tumors did not respond to either inhibitor. Our findings link pleiotrophin abundance in gliomas with survival in humans and mice, and show that pleiotrophin promotes glioma progression through increased VEGF deposition and vascular abnormalization.

Adult low-grade gliomas (LGG) are poorly circumscribed diffusely infiltrative brain tumours localised mainly in the cerebral hemispheres. They affect otherwise healthy individuals with an average age of ∼40 years at the time of diagnosis. Low-grade gliomas in adults are classified as grade II gliomas according to the World Health Organisation (WHO) classification of brain tumours and consist mainly of astrocytomas, oligodendrogliomas and oligoastrocytomas (Louis et al, 2007). The median survival for LGG is 5–10 years, but clinical outcome varies considerably (Lote et al, 1997). For some patients the disease has an indolent course for many years, whereas others experience rapid tumour progression from the time of diagnosis. Treatment is unsatisfactory and there is no cure for LGG (Soffietti et al, 2010). There is consensus but no evidence that maximal surgical resection prolongs survival in LGG (Keles et al, 2001; Duffau, 2009). A large randomised trial designed to define the optimal timing of radiotherapy showed a prolonged symptom-free survival for patients with LGG receiving adjuvant radiotherapy compared with those irradiated at progression, but no difference in overall survival (Karim et al, 2002; van den Bent et al, 2005). For optimal patient management, clinical parameters with an impact on survival have to be taken into account (Pignatti et al, 2002; Soffietti et al, 2010). Negative prognostic factors for survival are old age, astrocytoma histology, neurological deficit at presentation, large tumour diameter, contrast enhancement and tumours crossing midline (Pignatti et al, 2002). The presence of two or less unfavourable factors identifies low-risk groups, and for these low-risk patients it is probably a good strategy to defer radiotherapy until tumour progression (Pignatti et al, 2002). Many treatment decisions, however, remain unsolved. The clinical management of patients with LGG will benefit from prognostic and predictive biomarkers that can guide therapeutic decisions. One such example is the combined loss of chromosomal arms 1p/19q, the molecular hallmark of oligodendrogliomas and a strong prognostic and predictive marker in these tumours (Ohgaki and Kleihues, 2005). PROX1 is a transcription factor expressed in the heart, liver, lens, skeletal muscles, pancreas, kidney and in the CNS (Zinovieva et al, 1996). The Drosophila homologue of PROX1, prospero, resembles a tumour suppressor gene by preventing neuroblast self-renewal. In the absence of prospero, cells accumulate forming brain tumours (Betschinger et al, 2006). It has been suggested that PROX1 has a similar role in human malignancies. Decreased expression of PROX1 was found in hepatocellular carcinomas, sporadic breast cancer and carcinomas of the biliary system (Shimoda et al, 2006; Laerm et al, 2007; Versmold et al, 2007). In contrast, PROX1 was overexpressed in colorectal cancer and found to have a role in promoting cancer progression (Petrova et al, 2008). We have recently shown that PROX1 protein is overexpressed in human astrocytic tumours, with highest levels in grade III and IV astrocytomas (Elsir et al, 2010). These findings suggest that PROX1 may act as a prognostic factor in human gliomas. In the present study, we have studied the presence of PROX1 protein in correlation with patient survival in a cohort of patients with LGG.

PURPOSE: To process single voxel spectra of low- and high-grade gliomas. To propose correlation analysis of the scatter plots of normalized spectral amplitudes as a pattern recognition tool for the classification (grading) of brain tumors. To propose a spectrum processing approach that improves the differentiation of proton spectra with dominating macromolecule and lipid peaks. MATERIALS AND METHODS: LCModel was used to process spectra. Mean metabolite concentrations and mean normalized spectra were obtained for normal white matter and for gliomas. The mean spectra of macromolecules and lipids (ML) in the range 1.4-0.9 ppm, and mean difference spectra (DS) without ML and lactate were computed. Correlation analysis of the scatter plot of the patient and mean normalized spectral amplitudes and dispersion of the scatter plot points were used for classification and grading of tumors. RESULTS: It was found advantageous to perform the classifications using DS spectra. The shape of ML spectrum and concentration of tCr seem to be a good markers for glioma grade. CONCLUSION: Combining a qualitative comparison of the patient and mean DS spectra of the tumors using correlation analysis of normalized spectra amplitudes with a quantitative comparison of metabolite concentrations is a powerful tool in studying brain lesions.

Amyloid-beta (Abeta) is a major drug target in Alzheimer's disease. Here, we demonstrate that deposited Abeta is SDS insoluble in tgAPP-ArcSwe, a transgenic mouse model harboring the Arctic (E693G) and Swedish (KM670/671NL) APP mutations. Formic acid was needed to extract the majority of deposited Abeta in both tgAPP-ArcSwe and Alzheimer's disease brain, but not in a commonly used type of mouse model with the Swedish mutation alone. Interestingly, the insoluble state of Arctic Abeta was determined early on and did not gradually evolve with time. In tgAPP-ArcSwe, Abeta plaques displayed a patchy morphology with bundles of Abeta fibrils, whereas amyloid cores in tgAPP-Swe were circular with radiating fibrils. Amyloid was more densely stacked in tgAPP-ArcSwe, as demonstrated with a conformation sensitive probe. A reduced increase in plasma Abeta was observed following acute administration of an Abeta antibody in tgAPP-ArcSwe, results that might imply reduced brain to plasma Abeta efflux. TgAPP-ArcSwe, with its insoluble state of deposited Abeta, could serve as a complementary model to better predict the outcome of clinical trials.

Gliomas are primary brain tumors mainly affecting adults. The cellular origin is unknown. The recent identification of tumor-initiating cells in glioma, which share many similarities with normal neural stem cells, has suggested the cell of origin to be a transformed neural stem cell. In previous studies, using the RCAS/tv-a mouse model, platelet-derived growth factor B (PDGF-B)-induced gliomas have been generated from nestin or glial fibrillary acidic protein-expressing cells, markers of neural stem cells. To investigate if committed glial progenitor cells could be the cell of origin for glioma, we generated the Ctv-a mouse where tumor induction would be restricted to myelinating oligodendrocyte progenitor cells (OPCs) expressing 2',3'-cyclic nucleotide 3'-phosphodiesterase. We showed that PDGF-B transfer to OPCs could induce gliomas with an incidence of 33%. The majority of tumors resembled human WHO grade II oligodendroglioma based on close similarities in histopathology and expression of cellular markers. Thus, with the Ctv-a mouse we have showed that the cell of origin for glioma may be a committed glial progenitor cell.

Glioblastoma Multiforme (GBM) is the most frequent adult primary malignant brain tumor that remains incurable despite aggressive treatment. The cell of origin (COO) for GBM is unknown but assumed to be a glial stem or progenitor cell. GBM harbours hierarchical tumor cells called glioma stem cells (GSCs) that maintain tumor growth, drive tumor progression and cause tumor relapse due to their increased resistance to therapy. We have analyzed the significance of cellular origin for GBM development and GSC properties by comparing mouse GBMs and GSCs derived thereof induced in neural stem cells (NSCs), glial-restricted precursor cells (GPCs) or oligodendrocyte precursor cells (OPCs) by identical mutations. There were striking differences in GBM development and the phenotypes of GSCs and their response to drugs owing to the COO. Global gene expression analysis of mouse GSC lines displayed a clear separation due to COO and differential gene expression analysis identified a COO gene signature of 175 genes. Cross-species bioinformatics analyses were performed. First we analyzed the human cancer genome atlas (TCGA) GBM tissue samples and the mouse GSC expression data for a collection of TCGA GBM subtype signature genes. This showed that we could model both Proneural and Mesenchymal GBMs in mice by merely switching the COO. Next, we used the mouse COO gene signature to stratify a large number of newly established human glioma stem cell lines. This produced two groups of human GSCs; the NSC origin group and the progenitor cell (PC) origin group in which the mouse GPC- and OPC-derived genes were combined. Importantly, patient survival was significantly different between the NSC and PC COO groups with a better prognosis for the PC group patients. Thus, the cell of origin is essential for GBM biology and needs to be considered for more accurate patient stratification, target identification and drug discovery.

Stem cells, believed to be the cellular origin of glioma, are able to generate gliomas, according to experimental studies. Here we investigated the potential and circumstances of more differentiated cells to generate glioma development. We and others have shown that oligodendrocyte precursor cells (OPCs) can also be the cell of origin for experimental oligodendroglial tumors. However, the question of whether OPCs have the capacity to initiate astrocytic gliomas remains unanswered. Astrocytic and oligodendroglial tumors represent the two most common groups of glioma and have been considered as distinct disease groups with putatively different origins. Here we show that mouse OPCs can give rise to both types of glioma given the right circumstances. We analyzed tumors induced by K-RAS and AKT and compared them to oligodendroglial platelet-derived growth factor B-induced tumors inCtv-amice with targeted deletions ofCdkn2a(p16Ink4a−/−, p19Arf−/−, Cdkn2a−/−). Our results showed that glioma can originate from OPCs through overexpression of K-RAS and AKT when combined with p19Arfloss, and these tumors displayed an astrocytic histology and high expression of astrocytic markers. We argue that OPCs have the potential to develop both astrocytic and oligodendroglial tumors given loss of p19Arf, and that oncogenic signaling is dominant to cell of origin in determining glioma phenotype. Our mouse data are supported by the fact that human astrocytoma and oligodendroglioma display a high degree of overlap in global gene expression with no clear distinctions between the two diagnoses.

Background The Arctic mutation (p.E693G/p.E22G)fs within the β-amyloid (Aβ) region of the β-amyloid precursor protein gene causes an autosomal dominant disease with clinical picture of typical Alzheimer’s disease. Here we report the special character of Arctic AD neuropathology in four deceased patients. Results Aβ deposition in the brains was wide-spread (Thal phase 5) and profuse. Virtually all parenchymal deposits were composed of non-fibrillar, Congo red negative Aβ aggregates. Congo red only stained angiopathic vessels. Mass spectrometric analyses showed that Aβ deposits contained variably truncated and modified wild type and mutated Aβ species. In three of four Arctic AD brains, most cerebral cortical plaques appeared targetoid with centres containing C-terminally (beyond aa 40) and variably N-terminally truncated Aβ surrounded by coronas immunopositive for Aβx-42. In the fourth patient plaque centres contained almost no Aβ making the plaques ring-shaped. The architectural pattern of plaques also varied between different anatomic regions. Tau pathology corresponded to Braak stage VI, and appeared mainly as delicate neuropil threads (NT) enriched within Aβ plaques. Dystrophic neurites were scarce, while neurofibrillary tangles were relatively common. Neuronal perikarya within the Aβ plaques appeared relatively intact. Conclusions In Arctic AD brain differentially truncated abundant Aβ is deposited in plaques of variable numbers and shapes in different regions of the brain (including exceptional targetoid plaques in neocortex). The extracellular non-fibrillar Aβ does not seem to cause overt damage to adjacent neurons or to induce formation of neurofibrillary tangles, supporting the view that intracellular Aβ oligomers are more neurotoxic than extracellular Aβ deposits. However, the enrichment of NTs within plaques suggests some degree of intra-plaque axonal damage including accumulation of hp-tau, which may impair axoplasmic transport, and thereby contribute to synaptic loss. Finally, similarly as the cotton wool plaques in AD resulting from exon 9 deletion in the presenilin-1 gene, the Arctic plaques induced only modest glial and inflammatory tissue reaction.

Background: Angiogenesis is implicated in many pathological conditions. The role of the proteins involved remains largely unknown, and few vascular-specific drug targets have been discovered. Previously, in a screen for angiogenesis regulators, we identified Paladin (mouse: X99384, human: KIAA1274), a protein containing predicted S/T/Y phosphatase domains. Results: We present a mouse knockout allele for Paladin with a b-galactosidase reporter, which in combination with Paladin antibodies demonstrate that Paladin is expressed in the vasculature. During mouse embryogenesis, Paladin is primarily expressed in capillary and venous endothelial cells. In adult mice Paladin is predominantly expressed in arterial pericytes and vascular smooth muscle cells. Paladin also displays vascular-restricted expression in human brain, astrocytomas, and glioblastomas. Conclusions: Paladin, a novel putative phosphatase, displays a dynamic expression pattern in the vasculature. During embryonic stages it is broadly expressed in endothelial cells, while in the adult it is selectively expressed in arterial smooth muscle cells. Developmental Dynamics 241:770–786, 2012. V 2012 Wiley Periodicals, Inc.

The Arctic (p. E693G) mutation in the amyloid-β precursor protein (AβPP) facilitates amyloid-β (Aβ) protofibril formation and generates clinical symptoms of Alzheimer's disease (AD). Here, molecular details of Aβ in post mortem brain were investigated with biochemical and morphological techniques. The basic structure of Arctic plaques resembled cotton wool plaques. However, they appeared ring-formed with Aβ42-specific antibodies, but were actually targetoid, since the periphery and center of many parenchymal Aβ deposits stained differently with mid-domain, N- and C-terminal Aβ antibodies. Aβ fibrils were similar in shape, albeit shorter than in sporadic AD brain, when examined by electron microscopy. Aβwild-type and Aβarctic codeposited and parenchymal deposits were highly enriched in both N- and C-terminally truncated Aβ. In contrast, cerebral amyloid angiopathy (CAA) contained a substantial amount of Aβ1-40. The absence of plaques with cores of fibrillary Aβ might be due to the scarcity of full-length Aβ, although other mechanisms could be involved. Our findings are discussed in relation to mechanisms and relevance of amyloid formation and to the clinical features of AD.

Glioblastoma are aggressive astrocytic brain tumours characterized by microvascular proliferation and an abnormal vasculature, giving rise to brain oedema and increased patient morbidity. Here, we have characterized the transcriptome of tumour-associated blood vessels and describe a gene signature clearly associated with pleomorphic, pathologically altered vessels in human glioblastoma (grade IV glioma). We identified 95 genes differentially expressed in glioblastoma vessels, while no significant differences in gene expression were detected between vessels in non-malignant brain and grade II glioma. Differential vascular expression of ANGPT2, CD93, ESM1, ELTD1, FILIP1L and TENC1 in human glioblastoma was validated by immunohistochemistry, using a tissue microarray. Through qPCR analysis of gene induction in primary endothelial cells, we provide evidence that increased VEGF-A and TGFβ2 signalling in the tumour microenvironment is sufficient to invoke many of the changes in gene expression noted in glioblastoma vessels. Notably, we found an enrichment of Smad target genes within the distinct gene signature of glioblastoma vessels and a significant increase of Smad signalling complexes in the vasculature of human glioblastoma in situ. This indicates a key role of TGFβ signalling in regulating vascular phenotype and suggests that, in addition to VEGF-A, TGFβ2 may represent a new target for vascular normalization therapy.

To process single voxel spectra of low- and high-grade gliomas. To propose correlation analysis of the scatter plots of normalized spectral amplitudes as a pattern recognition tool for the classification (grading) of brain tumors. To propose a spectrum processing approach that improves the differentiation of proton spectra with dominating macromolecule and lipid peaks.LCModel was used to process spectra. Mean metabolite concentrations and mean normalized spectra were obtained for normal white matter and for gliomas. The mean spectra of macromolecules and lipids (ML) in the range 1.4-0.9 ppm, and mean difference spectra (DS) without ML and lactate were computed. Correlation analysis of the scatter plot of the patient and mean normalized spectral amplitudes and dispersion of the scatter plot points were used for classification and grading of tumors.It was found advantageous to perform the classifications using DS spectra. The shape of ML spectrum and concentration of tCr seem to be a good markers for glioma grade.Combining a qualitative comparison of the patient and mean DS spectra of the tumors using correlation analysis of normalized spectra amplitudes with a quantitative comparison of metabolite concentrations is a powerful tool in studying brain lesions.

Glioblastomas (GBs) are malignant CNS tumors often associated with devastating symptoms. Patients with GB have a very poor prognosis, and despite treatment, most of them die within 12 months from diagnosis. Several pathways, such as the RAS, tumor protein 53 (TP53), and phosphoinositide kinase 3 (PIK3) pathways, as well as the cell cycle control pathway, have been identified to be disrupted in this tumor. However, emerging data suggest that these aberrations represent only a fraction of the genetic changes involved in gliomagenesis. In this study, we have applied a 32K clone-based genomic array, covering 99% of the current assembly of the human genome, to the detailed genetic profiling of a set of 78 GBs. Complex patterns of aberrations, including high and narrow copy number amplicons, as well as a number of homozygously deleted loci, were identified. Amplicons that varied both in number (three on average) and in size (1.4 Mb on average) were frequently detected (81% of the samples). The loci encompassed not only previously reported oncogenes (EGFR, PDGFRA, MDM2, and CDK4) but also numerous novel oncogenes as GRB10, MKLN1, PPARGC1A, HGF, NAV3, CNTN1, SYT1, and ADAMTSL3. BNC2, PTPLAD2, and PTPRE, on the other hand, represent novel candidate tumor suppressor genes encompassed within homozygously deleted loci. Many of these genes are already linked to several forms of cancer; others represent new candidate genes that may serve as prognostic markers or even as therapeutic targets in the future. The large individual variation observed between the samples demonstrates the underlying complexity of the disease and strengthens the demand for an individualized therapy based on the genetic profile of the patient.

Mutations in the progranulin (PGRN) gene have recently been identified in families with frontotemporal lobar degeneration and ubiquitin-positive brain inclusions linked to chromosome 17q21. We have previously described a Swedish family displaying frontotemporal dementia with rapid progression and linkage to chromosome 17q21. In this study, we performed an extended clinical and neuropathological investigation of affected members of the family and a genetic analysis of the PGRN gene. There was a large variation of the initial presenting symptoms in this family, but common clinical features were non-fluent aphasia and loss of spontaneous speech as well as personality and behavioural changes. Mean age at onset was 54 years with disease duration of close to 4 years. Neuropathological examination revealed frontotemporal neurodegeneration with ubiquitin and TAR DNA binding protein-43 immunoreactive intraneuronal inclusions. Mutation screening of the PGRN gene identified a 1 bp deletion in exon 1 causing a frameshift of the coding sequence and introducing a premature termination codon in exon 2 (Gly35GlufsX19). Analysis of PGRN messenger RNA (mRNA) levels revealed a considerable decrease in lymphoblasts from mutation carriers and fragment size separation, and sequence analysis confirmed that the mutated mRNA allele was almost absent in these samples. In conclusion, the PGRN Gly35fs mutation causes frontotemporal dementia with variable clinical presentation in a large Swedish family, most likely through nonsense-mediated decay of mutant PGRN mRNA and resulting haploinsufficiency.

Grade II gliomas are morphologically and clinically heterogeneous tumors for which histopathological typing remains the major tool for clinical classification. To what extent the major histological subtypes - astrocytomas, oligodendrogliomas, and oligoastrocytomas - constitute true biological entities is largely unresolved. Furthermore, morphological classification is often ambiguous and would be facilitated by specific subtype markers. In this study, 23 grade II gliomas were expression-profiled and subjected to hierarchical clustering. All six oligodendrogliomas were grouped together in one of two major clusters; a significant correlation was thus observed between gene expression and histopathological subtype. Supervised analyses were performed to identify genes differentiating oligodendrogliomas from other grade II tumors. In a leave-one-out test using 10 features for classification, 20 out of 23 tumors were correctly classified. Among the most differentially expressed genes was rPTPbeta/zeta. The expression of the rPTP beta/zeta protein in oligodendrogliomas and astrocytomas was further validated by immunohistochemistry in an independent set of tumors. All 11 oligodendrogliomas of this set displayed strong staining. In contrast, neoplastic astrocytes were mostly negative for rPTPbeta/zeta staining. In summary, this study demonstrates a correlation between gene expression pattern and histological subtype in grade II gliomas. Furthermore, the results from the immunohistochemical analyses of rPTPbeta/zeta expression should prompt further evaluation of this protein as a novel oligodendroglioma marker.

In a previously published insertional mutagenesis screen for candidate brain tumor genes in the mouse using a Moloney mouse leukemia virus encoding platelet-derived growth factor (PDGF)-B, the Sox10 gene was tagged in five independent tumors. The proviral integrations suggest an enhancer effect on Sox10. All Moloney murine leukemia virus/PDGFB tumors had a high protein expression of Sox10 independently of malignant grade or tumor type. To investigate the role of Sox10 in gliomagenesis, we used the RCAS/tv-a mouse model in which the expression of retroviral-encoded genes can be directed to glial progenitor cells (Ntv-a mice). Both Ntv-a transgenic mice, wild-type, and Ntv-a p19Arf null mice were injected with RCAS-SOX10 alone or in combination with RCAS-PDGFB. Infection with RCAS-SOX10 alone did not induce any gliomas. Combined infection of RCAS-SOX10 and RCAS-PDGFB in wild-type Ntv-a mice yielded a tumor frequency of 12%, and in Ntv-a Arf−/− mice the tumor frequency was 30%. This indicates that Sox10 alone is not sufficient to induce gliomagenesis but acts synergistically with PDGFB in glioma development. All induced tumors displayed characteristics of PNET-like structures and oligodendroglioma. The tumors had a strong and widely distributed expression of Sox10 and PDGFR-α. We investigated the expression of Sox10 in other human tumors and in a number of gliomas. The Sox10 expression was restricted to gliomas and melanomas. All glioma types expressed Sox10, and tumors of low-grade glioma had a much broader distribution of Sox10 compared with high-grade gliomas. (Mol Cancer Res 2007;5(9):891–7)

Oligoastrocytomas are glial tumours consisting of a mixture of neoplastic astrocytic and oligodendroglial cells. Genetic alterations of oligoastrocytomas include loss of heterozygosity of chromosomes 1p and/or 19q (LOH 1p/19q), typically occurring in oligodendrogliomas, and mutations of TP53, frequently occurring in astrocytomas. To investigate whether these neoplastic cell types in oligoastrocytomas have different genetic profiles, we examined the two different components of oligoastrocytomas in comparison with the histological diagnosis of the specific tumour area for LOH 1p/19q and TP53 mutations by using microdissection technique. We found a variety of lost markers for 1p and 19q, and the presence of two different TP53 mutations in the tumour samples. In the majority of cases (9/11), the oligodendroglial and astrocytic components of an individual oligoastrocytoma displayed the same genotype. We present two cases of biphasic oligoastrocytomas with aberrant findings, suggesting the coexistence of genetically and morphologically distinct tumour cell clones in these tumours. In one case, the oligodendroglial part of the tumour showed LOH19q, whereas the astrocytic part showed TP53 mutation (codon 273). In another case, we found LOH 1p/19q in the oligodendroglial component, but two retained areas on chromosome 1p in the astrocytic component of the tumour. No evidence was found for the coexistence of tumour cells with the two genotypical changes within the same morphological region of one individual tumour. The two cases of biphasic oligoastrocytomas in our sample that display a different genotype in the astrocytic and oligodendroglial part of the tumour show that different components of an oligoastrocytoma may be derived from different cell clones during neoplastic transformation.

The PROX1 transcription factor, also known as Prospero in flies, plays a critical role in the development of various organs especially the lymphatic and central nervous systems. Mutations in Prospero induce brain tumor development in flies due to the lack of normal asymmetric neural stem cell division. Less is known about the expression and function of PROX1 in human brain tumors. First, we investigated expression of PROX1 using immunohistochemistry in 56 human astrocytic gliomas of different grades. PROX1 was found to be overexpressed in the majority of high grade tumors but not in grade I tumors or control tissue. Secondly, we addressed the prognostic value of PROX1 in a clinical cohort of patients with grade II gliomas (n=116). The number of PROX1 immunoreactive cells was used as a variable in survival analysis. Patients with tumors showing high PROX1 protein expression had poor outcome in the univariate analysis as well as in the multivariate analysis compared to those with low PROX1 expression. Thirdly, we found that PROX1 was expressed in glioma cell lines and we noted an apparent positive correlation between expression of PROX1 and the pluripotency factor SOX2. Depletion of SOX2 using siRNA inhibited glioma cell proliferation and reduced the levels of PROX1. Acute loss of PROX1 did not impair glioma cell proliferation in vitro. We conclude that PROX1 may constitute a useful tool for diagnosing and grading of astrocytic glioma distinguishing grade III and IV tumors from grade I and II tumors. PROX1 is also a novel predictor of survival for grade II gliomas. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5560. doi:1538-7445.AM2012-5560

Extensive angiogenesis, formation of new capillaries from pre-existing blood vessels, is an important feature of malignant glioma. Several antiangiogenic drugs targeting vascular endothelial growth factor (VEGF) or its receptors are currently in clinical trials as therapy for high-grade glioma and bevacizumab was recently approved by the FDA for treatment of recurrent glioblastoma. However, the modest efficacy of these drugs and emerging problems with anti-VEGF treatment resistance welcome the development of alternative antiangiogenic therapies. One potential candidate is histidine-rich glycoprotein (HRG), a plasma protein with antiangiogenic properties that can inhibit endothelial cell adhesion and migration. We have used the RCAS/TV-A mouse model for gliomas to investigate the effect of HRG on brain tumor development. Tumors were induced with platelet-derived growth factor-B (PDGF-B), in the presence or absence of HRG. We found that HRG had little effect on tumor incidence but could significantly inhibit the development of malignant glioma and completely prevent the occurrence of grade IV tumors (glioblastoma).

Curative therapy for medulloblastoma and other pediatric embryonal brain tumors has improved, but the outcome still remains poor and current treatment causes long-term complications. Malignant brain tumors infiltrate the healthy brain tissue and, thus despite resection, cells that have already migrated cause rapid tumor regrowth. Heparan sulfate proteoglycans (HSPG), major components of the extracellular matrix (ECM), modulate the activities of a variety of proteins. The major enzyme that degrades HS, heparanase (HPSE), is an important regulator of the ECM. Here, we report that the levels of HPSE in pediatric brain tumors are higher than in healthy brain tissue and that treatment of pediatric brain tumor cells with HPSE stimulated their growth. In addition, the latent, 65 kDa form of HPSE (that requires intracellular enzymatic processing for activation) enhanced cell viability and rapidly activated the ERK and AKT signaling pathways, before enzymatically active HPSE was detected. The HPSE inhibitor PG545 efficiently killed pediatric brain tumor cells, but not normal human astrocytes, and this compound also reduced tumor cell invasion in vitro and potently reduced the size of flank tumors in vivo. Our findings indicate that HPSE in malignant brain tumors affects both the tumor cells themselves and their ECM. In conclusion, HPSE plays a substantial role in childhood brain tumors, by contributing to tumor aggressiveness and thereby represents a potential therapeutic target. Mol Cancer Ther; 16(8); 1705–16. ©2017 AACR.