Neoplastic Astrocytes Research Articles

Neurofibromatosis type 1-associated optic pathway gliomas: pathogenesis and emerging treatments.

Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disorder associated with an increased risk of developing a variety of benign and malignant tumors. Fifteen to 20% of children with NF1 are diagnosed with an optic pathway glioma (NF1-OPG) before 7 years of age, and more than half of them experience visual decline. At present, no effective therapy is available for prevention, restoration, or even stabilization of vision loss in subjects affected by NF1-OPG. This paper aims to review the main emerging pharmacological approaches that have been recently assessed in preclinical and clinical settings. We performed a search of the literature using Embase, PubMed, and Scopus databases to identify articles regarding NF1-OPGs and their treatment up to July 1st, 2022. The reference lists of the analyzed articles were also considered a source of literature information. To search and analyze all relevant English articles, the following keywords were used in various combinations: neurofibromatosis type 1, optic pathway glioma, chemotherapy, precision medicine, MEK inhibitors, VEGF, nerve growth factor. Over the past decade, basic research and the development of genetically engineered mice models of NF1-associated OPG have shed light on the cellular and molecular mechanisms underlying the disease and inspired animal and human testing of several compounds. A promising line of research is focusing on the inhibition of mTOR, a protein kinase controlling proliferation, protein synthesis rate and cell motility that is highly expressed in neoplastic cells. Several mTOR blockers have been tested in clinical trials, the most recent of which employed oral everolimus with encouraging results. A different strategy aims at restoring cAMP levels in neoplastic astrocytes and non-neoplastic neurons, since reduced intracellular cAMP levels contribute to OPG growth and, more importantly, are the major determinant of NF1-OPG-associated visual decline. So far, however, this approach has only been attempted in preclinical studies. Stroma-directed molecular therapies - seeking to target Nf1 heterozygous brain microglia and retinal ganglion cells (RGCs) - are another fascinating field. Microglia-inhibiting strategies have not yet reached clinical trials, but preclinical studies conducted over the last 15 years have provided convincing clues of their potential. The importance of NF1-mutant RGCs in the formation and progression of OPGs also holds promise for clinical translation. The evidence of Vascular Endothelial Growth Factor (VEGF)- Vascular Endothelial Growth Factor (VEGFR) signaling hyperactivity in pediatric low-grade gliomas prompted the use of bevacizumab, an anti-VEGF monoclonal antibody, which was tested in children with low-grade gliomas or OPGs with good clinical results. Neuroprotective agents have also been proposed to preserve and restore RGCs and topical eye administration of nerve growth factor (NGF) has demonstrated encouraging electrophysiological and clinical results in a double-blind, placebo-controlled study. Traditional chemotherapy in patients with NF1-OPGs does not significantly ameliorate visual function, and its effectiveness in halting tumor growth cannot be considered a satisfactory result. Newer lines of research should be pursued with the goal of stabilizing or improving the vision, rather than reducing tumor volume. The growing understanding of the unique cellular and molecular characteristics of NF1-OPG, coupled with the recent publication of promising clinical studies, raise hope for a shift towards precision medicine and targeted therapies as a first-line treatment.

Evaluation of Baculoviruses as Gene Therapy Vectors for Brain Cancer.

We aimed to assess the potential of baculoviral vectors (BV) for brain cancer gene therapy. We compared them with adenoviral vectors (AdV), which are used in neuro-oncology, but for which there is pre-existing immunity. We constructed BVs and AdVs encoding fluorescent reporter proteins and evaluated their transduction efficiency in glioma cells and astrocytes. Naïve and glioma-bearing mice were intracranially injected with BVs to assess transduction and neuropathology. Transgene expression was also assessed in the brain of BV-preimmunized mice. While the expression of BVs was weaker than AdVs in murine and human glioma cell lines, BV-mediated transgene expression in patient-derived glioma cells was similar to AdV-mediated transduction and showed strong correlation with clathrin expression, a protein that interacts with the baculovirus glycoprotein GP64, mediating BV endocytosis. BVs efficiently transduced normal and neoplastic astrocytes in vivo, without apparent neurotoxicity. BV-mediated transgene expression was stable for at least 21 days in the brain of naïve mice, but it was significantly reduced after 7 days in mice systemically preimmunized with BVs. Our findings indicate that BVs efficiently transduce glioma cells and astrocytes without apparent neurotoxicity. Since humans do not present pre-existing immunity against BVs, these vectors may constitute a valuable tool for the delivery of therapeutic genes into the brain.

Centrin 2: A Novel Marker of Mature and Neoplastic Human Astrocytes.

As microtubule-organizing centers (MTOCs), centrosomes play a pivotal role in cell division, neurodevelopment and neuronal maturation. Among centrosomal proteins, centrin-2 (CETN2) also contributes to DNA repair mechanisms which are fundamental to prevent genomic instability during neural stem cell pool expansion. Nevertheless, the expression profile of CETN2 in human neural stem cells and their progeny is currently unknown. To address this question, we interrogated a platform of human neuroepithelial stem (NES) cells derived from post mortem developing brain or established from pluripotent cells and demonstrated that while CETN2 retains its centrosomal location in proliferating NES cells, its expression pattern changes upon differentiation. In particular, we found that CETN2 is selectively expressed in mature astrocytes with a broad cytoplasmic distribution. We then extended our findings on human autoptic nervous tissue samples. We investigated CETN2 distribution in diverse anatomical areas along the rostro-caudal neuraxis and pointed out a peculiar topography of CETN2-labeled astrocytes in humans which was not appreciable in murine tissues, where CETN2 was mostly confined to ependymal cells. As a prototypical condition with glial overproliferation, we also explored CETN2 expression in glioblastoma multiforme (GBM), reporting a focal concentration of CETN2 in neoplastic astrocytes. This study expands CETN2 localization beyond centrosomes and reveals a unique expression pattern that makes it eligible as a novel astrocytic molecular marker, thus opening new roads to glial biology and human neural conditions.

Clinically Manifesting, Naturally Occurring Fowl Glioma in a Leghorn Chicken in Germany.

Fowl glioma-inducing virus (FGV), a strain of avian leukosis virus (ALV) subgroup A, is the causal agent of fowl glioma characterized by multiple nodular astrocytic growths, gliosis, and lymphocytic encephalitis. Also associated with FGV infection are cases of cerebellar hypoplasia, perineuromas, and nonsuppurative myocarditis. Though fowl glioma has been recognized in several countries, most reports of FGV infection come from Japan. A 9-mo-old brown leghorn from a German farm with nine leghorns was presented to a veterinarian with an impaired general health with torticollis, tremor, and incoordination. Histopathology revealed multifocal nodular astrocytic growths, gliosis, and a lymphoplasmacytic encephalitis. Immunohistochemically, neoplastic astrocytes showed positivity for anti-ALV antibody. FGV was detected in the brain with nested reverse transcription-polymerase chain reaction (RT-PCR) and subsequent sequencing of PCR product. The remaining eight birds were screened for the presence of ALV with real-time RT-PCR. Four leghorns tested positive for exogenous ALV in nested RT-PCR with an identical nucleotide sequence as the leghorn with neurological symptoms. To the authors' knowledge this is the first report of a natural FGV infection in a brown leghorn in Germany with clinical manifestation.

Neurotherapeutic implications of sense and respond strategies generated by astrocytes and astrocytic tumours to combat pH mechanical stress.

AimsAstrocytes adapt to acute acid stress. Intriguingly, cancer cells with astrocytic differentiation thrive even better in an acidic microenvironment. How changes in extracellular pH (pHe) are sensed and measured by the cell surface assemblies that first intercept the acid stress, and how this information is relayed downstream for an appropriate survival response remains largely uncharacterized.Methods In vitro cell‐based studies were combined with an in vivo animal model to delineate the machinery involved in pH microenvironment sensing and generation of mechanoadaptive responses in normal and neoplastic astrocytes. The data was further validated on patient samples from acidosis driven ischaemia and astrocytic tumour tissues.ResultsWe demonstrate that low pHe is perceived and interpreted by cells as mechanical stress. GM3 acts as a lipid‐based pH sensor, and in low pHe, its highly protonated state generates plasma membrane deformation stress which activates the IRE1‐sXBP1‐SREBP2‐ACSS2 response axis for cholesterol biosynthesis and surface trafficking. Enhanced surface cholesterol provides mechanical tenacity and prevents acid‐mediated membrane hydrolysis, which would otherwise result in cell leakage and death.ConclusionsIn summary, activating these lipids or the associated downstream machinery in acidosis‐related neurodegeneration may prevent disease progression, while specifically suppressing this key mechanical ‘sense‐respond’ axis should effectively target astrocytic tumour growth.

Effective Perturbations of the Amplitude, Gating, and Hysteresis of IK(DR) Caused by PT-2385, an HIF-2α Inhibitor.

PT-2385 is currently regarded as a potent and selective inhibitor of hypoxia-inducible factor-2α (HIF-2α), with potential antineoplastic activity. However, the membrane ion channels changed by this compound are obscure, although it is reasonable to assume that the compound might act on surface membrane before entering the cell´s interior. In this study, we intended to explore whether it and related compounds make any adjustments to the plasmalemmal ionic currents of pituitary tumor (GH3) cells and human 13-06-MG glioma cells. Cell exposure to PT-2385 suppressed the peak or late amplitude of delayed-rectifier K+ current (IK(DR)) in a time- and concentration-dependent manner, with IC50 values of 8.1 or 2.2 µM, respectively, while the KD value in PT-2385-induced shortening in the slow component of IK(DR) inactivation was estimated to be 2.9 µM. The PT-2385-mediated block of IK(DR) in GH3 cells was little-affected by the further application of diazoxide, cilostazol, or sorafenib. Increasing PT-2385 concentrations shifted the steady-state inactivation curve of IK(DR) towards a more hyperpolarized potential, with no change in the gating charge of the current, and also prolonged the time-dependent recovery of the IK(DR) block. The hysteretic strength of IK(DR) elicited by upright or inverted isosceles-triangular ramp voltage was decreased during exposure to PT-2385; meanwhile, the activation energy involved in the gating of IK(DR) elicitation was noticeably raised in its presence. Alternatively, the presence of PT-2385 in human 13-06-MG glioma cells effectively decreased the amplitude of IK(DR). Considering all of the experimental results together, the effects of PT-2385 on ionic currents demonstrated herein could be non-canonical and tend to be upstream of the inhibition of HIF-2α. This action therefore probably contributes to down-streaming mechanisms through the changes that it or other structurally resemblant compounds lead to in the perturbations of the functional activities of pituitary cells or neoplastic astrocytes, in the case that in vivo observations occur.

Can permanent cell lines originate from low-grade astrocytomas: overgrowth of "glia-like" cells in pilocytic and fibrillary (diffuse) astrocytoma cultures.

Due inter alia to wide-spread cell lines cross-contamination it is not clear, which kind of normal or tumoral tissue give rise to permanent cell lines. Few permanent cell lines have been established from low-grade astrocytomas. However, recently some of these have been identified as being cross-contaminated with other cell lines. Morphology, cell growth and GFAP immunophenotype of low-grade astrocytomas were examined on 9 pilocytic and 15 fibrillary (diffuse) tissue cultures. GFAP-positive process-bearing cells were present in all the cultures, mainly during the first days in vitro (DIV). In pilocytic cultures, cells with hairy (piloid) processes were present. GFAP-positive cells completely disappeared by passages 3 to 5 and all the cultures contained only GFAP-negative "glia-like" cells, which underwent cellular senescence within passages 8 to 15. Key differences in the morphology and GFAP expression between the neoplastic astrocytes and normal "glia-like" cells allow the observation of perceptibly more rapid growth of normal cells in astrocytoma cultures. We caution that cultures prepared from macroscopically tumoral brain tissue may contain rapidly proliferating normal cells. Based on this and our previous studies in relation to the high percentage of cross-contaminated cell lines, we conclude that cells in low-grade astrocytoma cultures lack the capacity for spontaneous immortalization (Fig. 14, Ref. 15). Text in PDF www.elis.sk Keywords: pilocytic astrocytoma, fibrillary astrocytoma, "glia-like" cells, glioma cell lines, GFAP.

Anaplastic Ganglioglioma of the Pineal Region – A Case Report

<b>Introduction</b> Gangliogliomas are tumors commonly found in the temporal lobe and related to seizures; their appearance in the pineal region is rarely described. This report characterizes the first case of anaplastic ganglioglioma of the pineal region. <b>Case Report</b> The authors describe the case of a 32-year-old woman that developed progressive headache. An MRI investigation revealed a pineal tumor. The patient tested negative for biomarkers and underwent surgery through supracerebellar infratentorial approach and achieved gross total resection of the tumor in a challenging location. Pathological analysis revealed a biphasic neoplasm with the following two distinct phenotypes in separate fields: an immature neuronal component with several atypical mitoses and a mature astrocytic component with bipolar cells, microcysts, and eosinophilic bodies. The Ki67/MIB1 proliferation index was 20–30% in localized hotspots. Based on the pathological findings, the tumor was defined as an anaplastic ganglioglioma World Health Organization (WHO) grade III. <b>Discussion/Conclusion</b> Gangliogliomas are classified as glioneural neoplasms based on the histologic findings described as a mixture of neoplastic astrocytes and neurons. Moreover, these tumors represent 0.4–1.3% of tumors of the central nervous system. Authors describe de novo anaplastic ganglioglioma as 1% of the largest series. Gross total resection and adjuvant treatment may play important role in patients' prognostic. In this case, due to the malignant anaplastic component of her tumor, the patient received treatment with temozolamide and radiotherapy after gross total resection of the lesion.

ED-22 * CONCURRENCE OF GLIOMAS IN PATIENTS WITH MULTIPLE SCLEROSIS: CASE REPORT AND LITERATURE REVIEW

The concurrence of multiple sclerosis (MS) and gliomas is rare. Even though new symptoms in MS patients are likely due to disease progression, here we report a case demonstrating the importance of thorough clinical and radiologic evaluation and maintaining an open differential when investigating these new complaints. CASE REPORT: 79 year old man with MS diagnosed in 1980 managed on interferon-beta prior to 2009 complained of rapidly progressive cognitive decline in 12/2013 that began 3 months prior. Neurologic examination in 04/2014 revealed significant deterioration in memory and attention, worsened generalized weakness and ataxia, and the presence of aphasia, acalculia, and a left homonymous hemianopsia. A subsequent MRI brain with contrast showed a new extensive, infiltrative mass extending from the right parietoccipital region across a markedly expanded corpus callosum. CSF analysis demonstrated elevated protein, normal cell count, and negative EBV/ JC virus PCR and cytology. Pathology from a stereotactic biopsy confirmed the diagnosis of anaplastic glioma. The family declined further intervention and the patient died five days later in hospice. DISCUSSION: While MS complaints are broad and progressive, attributing all new, especially rapidly progressive, symptoms to MS should be cautioned. This case demonstrates the rare concurrence of MS and glioma. Limited data and epidemiology studies suggest that MS patients are not predisposed to primary brain tumors and coexistence of these entities does not influence the evolution of either disease. Data of long-term effects of immunomodulators used in the management of MS suggests no increased cancer risk. The most common brain tumors reported in MS patients include; oligodendroglioma, astrocytoma, glioblastoma, and gliomatosis cerebri. It is postulated that chronic inflammation in MS plaques induces neoplastic transformation of glial cells. However, contiguity between tumor and potentially neoplastic astrocytes within plaques is not always present. Additional research may determine the presence of any causal relationships.

P17.10 * GEMISTOCYTIC ASTROCYTOMAS: MONO-INSTITUTIONAL EXPERIENCE

Gemistocytic astrocytoma (GA) is variant of diffuse astrocytoma, characterized by the presence of at least 20% gemistocytic neoplastic astrocytes (usually around 35%, in the past 60%). They represent 9-19% of astrocytic tumors with median age at diagnosis of 40 years. Population-based studies on low grade gliomas suggest a worse prognosis for GA compared to fibrillary or protoplasmatic variants. WHO classification does not qualify GA as a high grade astrocytoma, since there is insufficient data to define gemistocytic morphology as an independent prognostic indicator. The mOS reported is 2.5 years, with a 5-year survival rate of 30%. In the present study we retrospectively identified all consecutive patients with proven gemistocytic astrocytoma diagnosed and treated in our Institution between 1985 and 2012 with the aim to correlate the clinical and histopathological findings with survival. Primary endpoint was OS in the whole group of patients and secondary endpoint was OS correlated to age and presence of anaplasia. A total of 78 patients (28 female, and 58 male), with median age at diagnosis 46 years, underwent surgical procedure at diagnosis (42% second surgery and 8% third surgery). In 32% (25/78 patients) of patients focal signs of anaplasia were described at diagnosis. 63% (49/78) underwent postoperative radiotherapy and 70.5% (55/78) underwent chemotherapy at different time points and with different schedules and drugs (nitrosureas, PCV, fotemustine, temozolomide). Median OS (in 78 patients) was 54 months (range 3-327 months). 26 patients were alive at the end of 2012. The mOS in 53 patients without anaplasia was 86 months (p 0,7 95%CI), mOS in 25 patients with anaplasia was 51 months (p 0,7 95%CI), mOS in 51 patients < 50 years was 86 months (p 0,27 95% CI), mOS in 27 patients ≥ 50 years was 42 months (p 0,27 95%CI). Despite several limitations of the study, our data show a median OS similar to other studies, with a better prognosis in patients younger than 50 years and in patients without focal anaplasia at diagnosis (data not statistically significant). Gemistocytic astrocytoma still continues to be enigmatic both in terms of definition and prognostic implications. Whether these tumors should be considered high grade astrocytomas remains open. Future prospective studies should clarify the value of gemistocytic morphology as an independent prognostic factor, and should investigate the molecular mechanisms that promote the formation of gemistocytes.

Cytoplasmic non-epithelial mucin accumulation associated with CD44 in an astrocytic tumor with signet ring features

We report a case of an atypical astrocytic tumor rich in signet ring cells with cytoplasmic mucin and glycogen in the left lower temporal lobe of the brain found in a Japanese female tricenarian. The signet ring cell cytoplasm contained bovine testicular hyaluronidase sensitive non-epithelial mucin together with CD44 and laminin. Glycogen was also detected. After subtotal resection, the residual tumor rapidly enlarged; hence, it was finally extirpated 8 months later followed by post-surgical irradiation. The recurrent tumor did not have signet ring cells and was entirely comprised of solid nests of large pale polygonal cells filled with glycogen and hyperchromatic nuclei. Mucin was not demonstrated in their cytoplasm, but their surface was diffusely coated with non-epithelial mucin together with CD44. The results of our analysis revealed that non-epithelial mucin could accumulate in or on the surface of neoplastic astrocytes in close association with CD44, findings that give new insights into the spectrum of non-epithelial mucin metabolism in astrocytic tumors. The tumor has not recurred for more than 3 years after the irradiation therapy following the second surgery, but further clinical observation is needed to evaluate the exact clinical behavior of this unusual tumor.

GFAP-Positive Neoplastic Astrocytes in Spontaneous Oligodendrogliomas and Mixed Gliomas of Rats

It is generally said that neoplastic cells are immunohistochemically negative for glial fibrillary acidic protein (GFAP) in rat spontaneous astrocytomas, and there are no reports describing the existence of GFAP-positive neoplastic astrocytes in rat spontaneous oligodendrogliomas and mixed gliomas which contain neoplastic astrocytes. In the present study, to clarify whether GFAP-positive neoplastic astrocytes exist in rat spontaneous oligodendrogliomas and mixed gliomas or not, immunohistochemical examination was performed on spontaneous oligodendrogliomas (26 cases) and mixed gliomas (5 cases) collected from the carcinogenicity studies and short-term toxicity studies. The neoplastic cells that constitute oligodendrogliomas and mixed gliomas were morphologically classified into five types: round A, round B, round C, spindle, and bizarre. The cells of round A, B, and C types were thought to be neoplastic oligodendrocytes because of their positive immunostainability for Olig2. The origin of bizarre cells was obscure because they were negative for Olig2, GFAP, and nestin. The spindle cells were considered to be neoplastic astrocytes, because some of them were positive for GFAP or nestin, and GFAP-positive spindle cells could be morphologically distinguished from reactive astrocytes. In conclusion, the present study clarified for the first time that GFAP-positive neoplastic astrocytes exist in rat spontaneous gliomas.

Two cases of desmoplastic non⁃infantile astrocytoma with review of the literature

Objective To investigate clinical pathological characteristics, diagnosis and differentiation of desmoplastic non ⁃ infantile astrocytoma (DNIA). Methods & Results Two female patients with DNIA aged 5 and 10 years old, respectively. The patient of case 1 had repeated unconsciousness with limbs twitch, MR image showed a mass in the inner part of the left temporal horn, the tumor was located in the underside of cortex of temporal lobe, about 3.00 cm × 3.50 cm × 3.50 cm in size with yellow in color and medium blood supply, the boundaries of the tumor were fairly clear and the mass was completely dissected. The patient of case 2 had recurrent headache with vomiting, MR image showed a large cystic solid mass in the right frontal temporal lobe⁃lateral ventricle. The tumor was located at 1 cm under the subcortex and drew off yellow cyst fluid about 80 ml. The tumor was about 11.00 cm × 10.00 cm × 10.00 cm in size with yellow in color and brittle texture and abundant blood supply, adhesion to the brain tissue and was completely dissected. Histology showed obvious interstitial fibrosis associated with neoplastic astrocytes with primary neuroepithelium. Immunohistochemical staining indicated that the expression of both tumor cells was positive for vimentin, GFAP, S⁃100, Nestin, and negative for CK, EMA, NeuN, the expression of primary cells was positive for Syn; Ki ⁃ 67 labeling index was 6% and 10% , respectively. Histochemical staining showed that the tumor cells were surrounded by reticular fibers. Patients were followed up for 18 and 52 months, respectively, both had no recurrence and metastasis. Conclusion DNIA is a rare supratentorial neuroepithelial tumor. The prognosis is generally good. It needs to be differentiated from other tumors, especially malignant glioma. DOI：10.3969/j.issn.1672⁃6731.2012.03.015

Expression of Interleukin-8 Receptor CXCR2 and Suppressor of Cytokine Signaling-3 in Astrocytic Tumors

The aim was to expand recently published information regarding the significance of the interleukin (IL)-8/p-STAT-3 (signal transducer and activator of transcription) pathway in astrocytomas, focusing on the IL-8 receptor, chemokine (C-X-C motif) receptor 2 (CXCR2), and the STAT-3 inhibitor SOCS-3 (suppressors of cytokine signaling). A total of 91 paraffin-embedded human astrocytoma tissues (grades II-IV) were investigated for the association of SOCS-3 and CXCR2 expression with clinicopathologic and morphometric microvascular characteristics, vascular endothelial growth factor (VEGF), IL-8 and p-STAT-3 expression and patient survival. Peripheral IL-8 secretion levels were assessed by enzyme-linked immunosorbent spot (ELISPOT). SOCS-3, p-STAT-3 and CXCR2 protein levels were also quantified by Western immunoblotting in six cases, and the protein levels of SOCS-3 and CXCR2 were correlated with the immunohistochemical expression of the respective proteins. All CXCR2-positive cases by Western immunoblotting displayed increased peripheral IL-8 secretion levels. Treatment of primary glioblastoma cell cultures with exogenous IL-8 enhanced proliferation, and this effect was inhibited by treatment with a neutralizing anti-CXCR2 antibody. SOCS-3 and CXCR2 were expressed by neoplastic astrocytes in 92.4% and 48.78% of cases, respectively, with their levels increasing with histological grade and extent of necrosis. VEGF expression and microvessel density, CXCR2 and IL-8 levels were interrelated. SOCS-3 and p-STAT-3 were co-expressed in 85.7% of cases, although they were not interrelated. In univariate survival analysis, increased SOCS-3 expression and the presence of CXCR2 adversely affected survival, whereas in multivariate analysis, only CXCR2 remained significant. The prognostic significance of CXCR2 was validated in an independent set of 63 patients. Our data implicate IL-8/CXCR2 signaling pathway in the progression and regulation of angiogenesis in astrocytomas and provide a rationale for CXCR2 therapeutic exploitation in these tumors.

Macrophage migration inhibitory factor (MIF) expression in human malignant gliomas contributes to immune escape and tumour progression

Macrophage migration inhibitory factor (MIF), which inhibits apoptosis and promotes angiogenesis, is expressed in cancers suppressing immune surveillance. Its biological role in human glioblastoma is, however, only poorly understood. We examined in-vivo expression of MIF in 166 gliomas and 23 normal control brains by immunohistochemistry. MIF immunoreactivity was enhanced in neoplastic astrocytes in WHO grade II glioma and increased significantly in higher tumour grades (III-IV). MIF expression was further assessed in 12 glioma cell lines in vitro. Quantitative RT-PCR showed that MIF mRNA expression was elevated up to 800-fold in malignant glioma cells compared with normal brain. This translated into high protein levels as assessed by immunoblotting of total cell lysates and by ELISA-based measurement of secreted MIF. Wild-type p53-retaining glioma cell lines expressed higher levels of MIF, which may be connected with the previously described role of MIF as a negative regulator of wild-type p53 signalling in tumour cells. Stable knockdown of MIF by shRNA in glioma cells significantly increased tumour cell susceptibility towards NK cell-mediated cytotoxicity. Furthermore, supernatant from mock-transfected cells, but not from MIF knockdown cells, induced downregulation of the activating immune receptor NKG2D on NK and CD8+ T cells. We thus propose that human glioma cell-derived MIF contributes to the immune escape of malignant gliomas by counteracting NK and cytotoxic T-cell-mediated tumour immune surveillance. Considering its further cell-intrinsic and extrinsic tumour-promoting effects and the availability of small molecule inhibitors, MIF seems to be a promising candidate for future glioma therapy.

A biobehavioral perspective on depressive symptoms in patients with cerebral astrocytoma.

More than 51,000 individuals are diagnosed with a primary brain tumor in the United States each year, and for those with the most common type of malignant tumor, an astrocytoma, almost 75% will die within 5 years of diagnosis. Although surgery, radiation, and chemotherapy have improved length of survival, mortality remains high, which underscores the need to understand how other factors affect the disease trajectory. Several recent studies have shown that depressive symptoms are independently associated with reduced quality of life and survival time after controlling for other variables in patients with an astrocytoma. Thus, depressive symptoms represent a significant risk factor for adverse outcomes in this patient population. A growing body of evidence indicates that depressive symptoms are linked to underlying biological phenomena, particularly inflammatory activation modulated through increased peripheral levels of proinflammatory cytokines. Recent research has shown that neoplastic astrocytes respond to elevated proinflammatory cytokine levels by secreting immune mediators within the central nervous system, including cytokines and glial fibrillary acidic protein that promote astrogliosis and angiogenesis and may increase tumor growth and metastasis. However, because these biological factors have not as yet been measured in conjunction with depressive symptoms in these patients, little is known about the interactions that potentially influence the treatment trajectory. To guide future research and to provide a deeper understanding of the factors that may influence depressive symptoms and length of survival in patients with an astrocytoma, a review of the literature was undertaken. Publications over the past 10 years were analyzed to examine the theoretical models and measures of depressive symptoms used in previous research. Although numerous studies have documented the relationship between depression and reduced length of survival, there were several methodological concerns identified, and there were no studies that included biological variables. Yet, research in the basic sciences provides compelling evidence of specific neuroendocrine-immune interactions orchestrated by astrocytes that can cause depressive symptoms and alter the tumor microenvironment so that standard treatments are not as effective. These findings support the need for clinically based research so that we can begin to understand the potentially modifiable biobehavioral mechanisms underlying depressive symptoms in patients with an astrocytoma. Grounded in the biobehavioral research paradigm of psychoneuroimmunology, a novel research program is presented that may provide a new level of understanding regarding the high prevalence of depressive symptoms in patients with an astrocytoma and lead to new treatment strategies, with possible implications for improved symptom management and quality of life in patients with brain tumors.

WT1 Is Not a Reliable Marker to Distinguish Reactive from Neoplastic Astrocyte Populations in the Central Nervous System

A diagnostic difficulty in neuropathology practice is distinguishing reactive from neoplastic astrocyte populations. This is particularly true in small biopsy samples that lack evidence of increased cellularity or mitotic activity, microvascular proliferation, or necrosis. We performed the current study to validate the previously reported finding that in the central nervous system, the expression of WT1 is limited to neoplastic astrocytes. We retrospectively studied WT1 protein expression by immunohistochemistry (IHC) in 100 formalin-fixed, paraffin-embedded brain tissue samples consisting of 3 normal control tissues, 44 cases of reactive gliosis, 49 gliomas and 4 lesions suspicious for glioma. In normal human cortex, WT1 staining was restricted to vascular endothelium. Most cases of reactive gliosis (82%) showed at least focal WT1 positivity, and analysis of specimens with electrode monitoring lesions showed an inverse relationship between WT1 expression intensity and the number of days from electrode placement to tissue resection. All glioma samples (100%) and all cases suspicious for glioma (100%) showed at least focal WT1 positivity. Our results likely differ from those in the prior report because of differences in tissue fixation and IHC methodology. Thus, our findings indicate that WT1 expression alone is not a reliable feature to distinguish reactive from neoplastic astrocytes.

The glioma cell edge – winning by engulfing the enemy?

Malignant glioma and glioblastoma multiforme form the largest group of highly malignant brain tumours, for which there is yet no definitive cure. Different approaches to treatment have been tried, in vain or with minimal benefit for the patient. In addition to surgery, radiation and chemotherapy, immunotherapy aiming at evoking an inflammatory reaction against the tumour itself has been tried. Immunotherapy has shown good results in an experimental mouse model, but no convincing efficacy/success in patients. Why are the gliomas always winning, how do they take the lead? The following phenomena lead us to propose an hypothesis about the reason for the glioma lead: the reported findings of phagocytic activity in reactive and neoplastic astrocytes in animal models and humans; the frequently observed ingested "non-self material"/debris in glioma cells; the markedly high contents of tumour cells with phagocytic phenotype in gliomas and the signs of only limited and temporary inflammatory reactions in different immunotherapy attempts. Whether it being a true phagocytosis, an engulfing or comparable activity by the glioma cells, contributing to the tumour's self defense against e.g. antitumoural therapies, it should be beneficial to attempt hampering these self defense properties e.g. by blocking their engulfing capacity.

EGR‐1 is Regulated by N‐Methyl‐D‐Aspartate‐Receptor Stimulation and Associated with Patient Survival in Human High Grade Astrocytomas

Early growth response-1 (EGR-1) is considered a central regulator in tumor cell proliferation, migration and angiogenesis and a promising candidate for gene therapy in human astrocytomas. However, conflicting data have been reported suggesting that both tumor promoting and anti-tumor activity of EGR-1 and its regulation, expression and prognostic significance still remain enigmatic. Our study explored EGR-1 expression and regulation in astrocytomas and its association with patient survival. As we detected two EGR-1 mRNA variants, one containing a N-methyl-D-aspartate-receptor (NMDA-R) responsive cytoplasmic polyadenylation element (CPE), further experiments were performed to determine the functional role of this pathway. After NMDA stimulation of SV-FHAS and neoplastic astrocytes, real-time polymerase chain reaction showed an increase of the CPE, containing EGR-1 splice variant only in astrocytoma cells. The surface expression and functionality of NMDA-R were demonstrated by flow cytometric analysis and measurement of increased intracellular Ca(2+). EGR-1 was mainly restricted to tumor cells expressing NMDA-R and significantly up-regulated in astrocytic tumors compared with normal brain. Further, EGR-1 expression was significantly (P < 0.007) associated with enhanced patient survival and was an independent prognostic factor in multivariate analysis in high grade astrocytomas. The NMDA-R-mediated EGR-1 expression, therefore, seems to be a promising target for novel clinical approaches to astrocytoma treatment.

Epilepsy in glioblastoma multiforme: correlation with glutamine synthetase levels

The hypothesis addressed by this study is that a glutamine synthetase (GS) deficiency in neoplastic astrocytes is a possible molecular basis associated with seizure generation in glioblastoma multiforme (GBM). Quantitative Western blot analysis of GS was performed in 20 individuals operated for malignant glioma. The levels of GS in patients with GBM and epilepsy were significantly lower (range 0.04-1.15; mean 0.35 +/- 0.36; median 0.25) than in non-epileptic GBM individuals (range 0.78-3.97; mean 1.64 +/- 0.99; median 1.25; P = 0.002). No relationship has been found between histological features (i.e. necrosis, gliosis, stroma, inflammatory cells, giant cells, and haemosiderine) and GS expression or epilepsy. Even though the epileptogenesis in glioma is multifactorial, it is conceivable that a down-regulation of GS may have an important pro-epileptogenic role in GBM, through the slowing of glutamate-glutamine cycle. This study suggests that seizures in GBM are coupled with a highly localized enzyme deficiency. The manipulation of GS activity might constitute a novel principle for inhibiting seizures in patients with glioma epilepsy.