Here we show that glioblastoma express high levels of branched-chain amino acid transaminase 1 (BCAT1), the enzyme that initiates the catabolism of branched-chain amino acids (BCAAs). Expression of BCAT1 was exclusive to tumors carrying wild-type isocitrate dehydrogenase 1 (IDH1) and IDH2 genes and was highly correlated with methylation patterns in the BCAT1 promoter region. BCAT1 expression was dependent on the concentration of α-ketoglutarate substrate in glioma cell lines and could be suppressed by ectopic overexpression of mutant IDH1 in immortalized human astrocytes, providing a link between IDH1 function and BCAT1 expression. Suppression of BCAT1 in glioma cell lines blocked the excretion of glutamate and led to reduced proliferation and invasiveness in vitro, as well as significant decreases in tumor growth in a glioblastoma xenograft model. These findings suggest a central role for BCAT1 in glioma pathogenesis, making BCAT1 and BCAA metabolism attractive targets for the development of targeted therapeutic approaches to treat patients with glioblastoma.

Malignant gliomas are the most common primary brain tumors, and are associated with frequent resistance to therapy as well as poor prognosis. Here we demonstrate that the nuclear receptor tailless (Tlx), which in the adult is expressed exclusively in astrocyte-like B cells of the subventricular zone, acts as a key regulator of neural stem cell (NSC) expansion and brain tumor initiation from NSCs. Overexpression of Tlx antagonizes age-dependent exhaustion of NSCs in mice and leads to migration of stem/progenitor cells from their natural niche. The increase of NSCs persists with age, and leads to efficient production of newborn neurons in aged brain tissues. These cells initiate the development of glioma-like lesions and gliomas. Glioma development is accelerated upon loss of the tumor suppressor p53. Tlx-induced NSC expansion and gliomagenesis are associated with increased angiogenesis, which allows for the migration and maintenance of brain tumor stem cells in the perivascular niche. We also demonstrate that Tlx transcripts are overexpressed in human primary glioblastomas in which Tlx expression is restricted to a subpopulation of nestin-positive perivascular tumor cells. Our study clearly demonstrates how NSCs contribute to brain tumorgenesis driven by a stem cell-specific transcription factor, thus providing novel insights into the histogenesis and molecular pathogenesis of primary brain tumors.

Purpose: Glioblastoma spheroid cultures are enriched in tumor stem-like cells and therefore may be more representative of the respective primary tumors than conventional monolayer cultures. We exploited the glioma spheroid culture model to find novel tumor-relevant genes. Experimental Design: We carried out array-based comparative genomic hybridization of spheroid cultures derived from 20 glioblastomas. Microarray-based gene expression analysis was applied to determine genes with differential expression compared with normal brain tissue and to nonneoplastic brain spheroids in glioma spheroid cultures. The protein expression levels of three candidates were determined by immunohistochemistry on tissue microarrays and correlated with clinical outcome. Functional analysis of PDPN was done. Results: Genomic changes in spheroid cultures closely resembled those detected in primary tumors of the corresponding patients. In contrast, genomic changes in serumgrown monolayer cultures established from the same patients did not match well with the respective primary tumors. Microarray-based gene expression analysis of glioblastoma spheroid cultures identified a set of novel candidate genes being upregulated or downregulated relative to normal brain. Quantitative real-time PCR analyses of 8 selected candidate genes in 20 clinical glioblastoma samples validated the microarray findings. Immunohistochemistry on tissue microarrays revealed that expression of AJAP1, EMP3, and PDPN was significantly associated with overall survival of astrocytic glioma patients. Invasive capacity and RhoA activity were decreased in PDPN-silenced spheroids. Conclusion: We identified a set of novel candidate genes that likely play a role in glioblastoma pathogenesis and implicate AJAP1, EMP3, and PDPN as molecular markers associated with the clinical outcome of glioma patients. (Clin Cancer Res 2009;15(21):6541-50) Glioblastoma is the most common and most malignant primary brain tumor and has one of the worst survival rates among all human cancers. Despite aggressive multimodal treatment, the median survival time after diagnosis has improved only marginally and is still <1 year in population-based studies (1). A better understanding of the complex molecular and cellular mechanisms leading to glioblastoma is an important prerequisite to

Background: Hidradenitis suppurativa (HS) is a neglected chronic inflammatory disease with long delay in diagnosis. Besides pain, purulent discharge, and destruction of skin architecture, HS patients experience metabolic, musculoskeletal, and psychological disorders. Objectives: To determine the delay in HS diagnosis and its consequences for patients and the healthcare system. Methods: This was a prospective, multicenter, epidemiologic, non-interventional cross-sectional trial carried out in Germany and based on self-reported questionnaires and medical examinations performed by dermatologists. In total, data of 394 adult HS patients were evaluated. Results: The average duration from manifestation of first symptoms until HS diagnosis was 10.0 ± 9.6 (mean ± SD) years. During this time, HS patients consulted on average more than 3 different physicians-most frequently general practitioners, dermatologists, surgeons, gynecologists-and faced more than 3 misdiagnoses. Diagnosis delay was longer in younger and non-smoking patients. In most cases, HS was correctly diagnosed by dermatologists. The longer the delay of diagnosis, the greater the disease severity at diagnosis. Delayed HS diagnosis was also associated with an increased number of surgically treated sites, concomitant diseases, and days of work missed. Conclusion: This study demonstrates an enormous delay in the diagnosis of HS, which results in more severe disease. It also shows for the first time that a delay in diagnosis of a chronic inflammatory disease leads to a higher number of concomitant systemic disorders. In addition to the impaired health status, delayed diagnosis of HS was associated with impairment of the professional life of affected people.

The concept of cancer stem-like cells (CSCs) has gained considerable attention in various solid tumors including glioblastoma, the most common primary brain tumor. This sub-population of tumor cells has been intensively investigated and their role in therapy resistance as well as tumor recurrence has been demonstrated. In that respect, development of therapeutic strategies that target CSCs (and possibly also the tumor bulk) appears a promising approach in patients suffering from primary brain tumors. In the present study, we utilized RNA interference (RNAi) to screen the complete human kinome and phosphatome (682 and 180 targets, respectively) in order to identify genes and pathways relevant for the survival of brain CSCs and thereby potential therapeutical targets for glioblastoma. We report of 46 putative candidates including known survival-related kinases and phosphatases. Interestingly, a number of genes identified are involved in metabolism, especially glycolysis, such as PDK1 and PKM2 and, most prominently PFKFB4. In vitro studies confirmed an essential role of PFKFB4 in the maintenance of brain CSCs. Furthermore, high PFKFB4 expression was associated with shorter survival of primary glioblastoma patients. Our findings support the importance of the glycolytic pathway in the maintenance of malignant glioma cells and brain CSCs and imply tumor metabolism as a promising therapeutic target in glioblastoma.

To identify novel glioma‐associated pathomechanisms and molecular markers, we performed an array‐based comparative genomic hybridization analysis of 131 diffuse astrocytic gliomas, including 87 primary glioblastomas (pGBIV), 13 secondary glioblastomas (sGBIV), 19 anaplastic astrocytomas (AAIII) and 12 diffuse astrocytomas (AII). All tumors were additionally screened for IDH1 and IDH2 mutations. Expression profiling was performed for 74 tumors (42 pGBIV, 11 sGBIV, 13 AAIII, 8 AII). Unsupervised and supervised bioinformatic analyses revealed distinct genomic and expression profiles separating pGBIV from the other entities. Classifier expression signatures were strongly associated with the IDH1 gene mutation status. Within pGBIV, the rare subtype of IDH1 mutant tumors shared expression profiles with IDH1 mutant sGBIV and was associated with longer overall survival compared with IDH1 wild‐type tumors. In patients with IDH1 wild‐type pGBIV, PDGFRA gain or amplification as well as 19q gain were associated with patient outcome. Array‐CGH analysis additionally revealed homozygous deletions of the FGFR2 gene at 10q26.13 in 2 pGBIV, with reduced FGFR2 mRNA levels being frequent in pGBIV and linked to poor outcome. In conclusion, we report that diffuse astrocytic gliomas can be separated into 2 major molecular groups with distinct genomic and mRNA profiles as well as IDH1 gene mutation status. In addition, our results suggest FGFR2 as a novel glioma‐associated candidate tumor suppressor gene on the long arm of chromosome 10.

Recently, we found strong overexpression of the mucin-type glycoprotein podoplanin (PDPN) in human astrocytic brain tumors, specifically in primary glioblastoma multiforme (GB). In the current study, we show an inverse correlation between PDPN expression and PTEN levels in primary human GB and glioma cell lines, and we report elevated PDPN protein levels in the subventricular zone of brain tissue sections of PTEN-deficient mice. In human glioma cells lacking functional PTEN, reintroduction of wild-type PTEN, inhibition of the PTEN downstream target protein kinase B/AKT, or interference with transcription factor AP-1 function resulted in efficient downregulation of PDPN expression. In addition, we observed hypoxia-dependent PDPN transcriptional control and demonstrated that PDPN expression is subject to negative transcriptional regulation by promoter methylation in human GB and in glioma cell lines. Treatment of PTEN-negative glioma cells with demethylating agents induced expression of PDPN. Together, our findings show that increased PDPN expression in human GB is caused by loss of PTEN function and activation of the PI3K-AKT-AP-1 signaling pathway, accompanied by epigenetic regulation of PDPN promoter activity. Silencing of PDPN expression leads to reduced proliferation and migration of glioma cells, suggesting a functional role of PDPN in glioma progression and malignancy. Thus, specific targeting of PDPN expression and/or function could be a promising strategy for the treatment of patients with primary GB.

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