Academic literature on the topic 'Pseudopalisading'

Background: Making an automatic diagnosis based on virtual slides and whole slide imaging or even determining whether a case belongs to a single class, representing a specific disease, is a big challenge. In this work we focus on WHO Classification of Tumours of the Central Nervous System. We try to design a method which allows to automatically distinguish virtual slides which contain histopathologic patterns characteristic of glioblastoma – pseudopalisading necrosis and discriminate cases with neurinoma (schwannoma), which contain similar structures – palisading (Verocay bodies).Methods: Our method is based on computer vision approaches like structural analysis and shape descriptors. We start with image segmentation in a virtual slide, find specific patterns and use a set of features which can describe pseudopalisading necrosis and distinguish it from palisades. Type of structures found in a slide decides about its classification.Results: Described method is tested on a set of 49 virtual slides, captured using robotic microscope. Results show that 82% of glioblastoma cases and 90% of neurinoma cases were correctly identified by the proposed algorithm.Conclusion: Our method is a promising approach to automatic detection of nervous system tumors using virtual slides.

Glioblastoma multiforme (GBM), an aggressive brain tumor, is characterized histologically by the presence of a necrotic center surrounded by so-called pseudopalisading cells. Pseudopalisading necrosis has long been used as a prognostic feature. However, the underlying molecular mechanism regulating the progression of GBMs remains unclear. We hypothesized that the gene expression profiles of individual cancers, specifically necrosis-related genes, would provide objective information that would allow for the creation of a prognostic index. Gene expression profiles of necrotic and nonnecrotic areas were obtained from the Ivy Glioblastoma Atlas Project (IVY GAP) database to explore the differentially expressed genes.A robust signature of seven genes was identified as a predictor for glioblastoma and low-grade glioma (GBM/LGG) in patients from The Cancer Genome Atlas (TCGA) cohort. This set of genes was able to stratify GBM/LGG and GBM patients into high-risk and low-risk groups in the training set as well as the validation set. The TCGA, Repository for Molecular Brain Neoplasia Data (Rembrandt), and GSE16011 databases were then used to validate the expression level of these seven genes in GBMs and LGGs. Finally, the differentially expressed genes (DEGs) in the high-risk and low-risk groups were subjected to gene ontology enrichment, Kyoto Encyclopedia of Genes and Genomes pathway, and gene set enrichment analyses, and they revealed that these DEGs were associated with immune and inflammatory responses. In conclusion, our study identified a novel seven-gene signature that may guide the prognostic prediction and development of therapeutic applications.

Overview: Glioblastoma (GBM) is a highly malignant, rapidly progressive astrocytoma that is distinguished pathologically from lower-grade tumors by necrosis and microvascular hyperplasia. The global pattern of growth changes dramatically with the development of GBM histology and is characterized by hypoxia-driven peripheral expansion from a growing necrotic core. Necrotic foci present centrally in GBM and are typically surrounded by “pseudopalisading” cells—a configuration that is relatively unique and long recognized as an ominous prognostic feature. Theses pseudopalisades are severely hypoxic, overexpress hypoxia inducible factor-1 (HIF-1), and secrete proangiogenic factors, such as vascular endothelial growth factor (VEGF) and interleukin 8 (IL-8). The microvascular hyperplasia that emerges in response promotes peripheral tumor expansion. Recent evidence suggests that pseudopalisades represent a wave of tumor cells actively migrating away from central hypoxia that arises following a vascular insult. Vaso-occlusive and prothrombotic mechanisms in GBM could readily explain the presence of pseudopalisading necrosis in tissue sections, the rapid peripheral expansion on neuroimaging, and the dramatic shift to an accelerated rate of clinical progression as a result of hypoxia-induced angiogenesis. The genetic alterations that coincide with progression to GBM include amplification of epidermal growth factor receptor (EGFR), deletion of CDKN2A, and mutation or deletion of PTEN. Other diagnostic and prognostic tests used in neuro-oncology include assessment of 1p/19q, MGMT promoter methylation, IDH1, and p53. More recently, the Cancer Genome Atlas data have indicated that there are four robust transcriptional classes of GBM, referred to as proneural, neural, classical, and mesenchymal. These classes have genetic associations and may pave the road for future development of targeted therapies.

Abstract Context.—Classic diagnostic neuropathologic teachings have cautioned against making the diagnosis of neoplasia in the presence of a macrophage population. The knowledge of macrophage distribution should prove useful when confronted with an infiltrating glioma containing macrophages. Objective.—To identify macrophages in untreated, infiltrating gliomas using the monoclonal antibody HAM56, and to confirm their presence in an untreated glioblastoma multiforme (GBM) with the serial analysis of gene expression (SAGE) method. Methods.—We evaluated the presence of macrophages in 16 cases of untreated, supratentorial infiltrating gliomas with the macrophage monoclonal antibody HAM56. We performed SAGE for one case of GBM and for normal brain tissue. Results.—In World Health Organization (WHO) grade II well-differentiated astrocytoma and oligodendroglioma, HAM56 reactivity was noted only in endothelial cells, and unequivocal macrophages were not identified. In WHO grade III anaplastic astrocytoma and anaplastic oligodendroglioma, rare HAM56-positive macrophages were noted in solid areas of tumor. In WHO grade IV GBM, HAM56-positive macrophages were identified in areas of solid tumor (mean labeling index, 8.6%). In all cases of GBM, nonquantitated HAM56-positive macrophages were identified in foci of pseudopalisading cells abutting necrosis and in foci of microvascular proliferations. In none of the cases were granulomas or microglial nodules found, and there was no prior history of surgical intervention, radiation therapy, chemotherapy, or head trauma in these cases. By SAGE, the macrophage-related proteins osteopontin and macrophage-capping protein were overexpressed 12-fold and eightfold, respectively, in one untreated GBM compared with normal brain tissue. In this case, numerous HAM56-positive macrophages (labeling index, 24.5%) were present in the solid portion of tumor, and abundant nonquantified macrophages were identified in foci of pseudopalisading cells abutting necrosis and in foci of microvascular proliferations. Conclusions.—This study confirms the utility of the monoclonal antibody HAM56 in identifying macrophages within untreated infiltrating gliomas. The overexpression of macrophage-related proteins in one case of GBM as detected by SAGE signifies that macrophages may be present in untreated GBMs.

✓ The distribution of transferrin receptor (TfR) in normal human brain-tissue obtained at autopsy and in brain-tumor biopsy specimens from 27 patients was determined by immunohistochemistry using two specific murine monoclonal antibodies against human TfR. The tumors studied included 10 glioblastomas multiforme (GBM's), nine other glial tumors, and eight meningiomas. In normal brain, TfR was detected primarily in endothelial cells; rare glial cells also contained immunoreactive product. All tumors contained TfR-positive cells, although the intensity (number of cells stained) and pattern (focal vs. diffuse) of staining varied with the histopathological type of the tumor. Among gliomas, the most intense staining was seen in GBM's, especially in areas of pseudopalisading where virtually all cells were stained. A rough correlation between tumor grade, number of positively stained cells, and staining pattern was seen in the other astrocytic tumors. By contrast, all meningiomas demonstrated an identical and characteristic focal staining pattern. Considering the differential immunostaining for TfR between normal and neoplastic tissue, the authors conclude that TfR may be an appropriate target for monoclonal antibody-directed brain-tumor immunotherapy, especially in more malignant tumors such as GBM's.

Abstract The difficulty in treatment of glioblastoma is a consequence of its natural infiltrative growth and the existence of a population of therapy-resistant glioma cells that contribute to growth and recurrence. To identify cells more likely to have these properties, we examined the expression in tumor specimens of several protein markers important for glioma progression including the intermediate filament protein, Nestin (NES), a glucose transporter (Glut1/SLC2A1), the glial lineage marker, glial fibrillary acidic protein, and the proliferative indicator, Ki-67. We also examined the expression of von Willebrand factor, a marker for endothelial cells as well as the macrophage/myeloid markers CD163 and CD15. Using a multicolor immunofluorescence and hematoxylin and eosin staining approach with archival formalin-fixed, paraffin embedded tissue from primary, recurrent, and autopsy IDH1 wildtype specimens combined with high-resolution tissue image analysis, we have identified highly proliferative NES(+)/Glut1(–) cells that are preferentially perivascular. In contrast, Glut1(+)/NES(–) cells are distant from blood vessels, show low proliferation, and are preferentially located at the borders of pseudopalisading necrosis. We hypothesize that Glut1(+)/NES(–) cells would be naturally resistant to conventional chemotherapy and radiation due to their low proliferative capacity and may act as a reservoir for tumor recurrence.

Abstract Cancer cells optimize nutrient utilization to supply energetic and biosynthetic pathways. These metabolic processes also include redox maintenance and epigenetic regulation through nucleic acid and protein methylation, enhancing tumorigenicity and clinical resistance. But less is known about how cancer cells exhibit metabolic flexibility to sustain cell growth and survival from nutrient starvation. Here, we identify a key role for serine availability and one-carbon metabolism in the survival of glioma cells from glutamine deprivation. To identify metabolic response to glutamine deprivation in glioma cells, we analyzed metabolites using gas chromatography and mass spectroscopy (GC/MS) in glioma cells cultured in glutamine-deprived medium and examined gene expression of key enzymes for one-carbon units using RT-PCR and western blotting methods. These expressions were also confirmed by immunohistochemical staining in glioma clinical samples Metabolome studies indicated serine, cysteine, and methionine as key differentiating amino acids between control and glutamine-deprived groups. Serine synthesis was mediated through autophagy rather than glycolysis. Gene expression analysis identified upregulation of Methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) to regulate serine synthesis and one-carbon metabolism. Importantly, suppression of this metabolite impaired glioma cell survival in glutamine deprivation. In human glioma samples. MTHFD2 expressions were highest in poorly nutrient regions around “pseudopalisading necrosis”. Serine-dependent one-carbon metabolism has a key role for glioma cells to survive glutamine starvation. These results may suggest the new therapeutic strategies targeting critical glioma cells adapting the tumor microenvironment.

Orientador: Liana Maria Cardoso Verinaud, Roger Chammas
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Gliomas são tumores primários do sistema nervoso central e o glioblastoma multiforme é sua forma clínica mais comum e de pior prognóstico. Na tentativa de entender sua biologia, a linhagem NG97 foi estabelecida, demonstrando características de glioblastoma com atipia nuclear e elevadas taxas de mitose. Recentemente, descobriu-se que esta é uma linhagem híbrida humano-murina derivada da fusão de células de astrocitoma humano e estroma murino que provavelmente ocorreu no processo de estabelecimento desta linhagem, a qual foi posteriormente denominada NG97ht. Esta linhagem apresenta crescimento de massas tumorais quando inoculada em camundongos imunodeficientes, demonstrando características histopatológicas de pseudopaliçada, comuns a glioblastomas. Estas são regiões hipercelulares que margeiam ambientes necróticos e postula-se que sejam células migrantes de ambientes necróticos/hipóxicos. Além disso, estas áreas têm como característica a expressão de moléculas relacionadas à adaptação a hipóxia, como o fator induzido por hipóxia (HIF), atuando na sobrevivência celular pela indução de diferentes genes. É visto que em hipóxia há aumento da produção de galectina-3, a qual está envolvida em diversos processos celulares e que é somente expressa nestas regiões de pseudopaliçada, não sendo detectada em suas áreas tumorais adjacentes. A galectina-3 é uma lectina que possui ligação a beta-galactosídeos e se relaciona com o aumento da mobilidade, adesão, crescimento e progressão tumoral. Além disso, estudos indicam que em alguns tipos tumorais, a metilação do promotor de galectina-3 é responsável pela modulação de sua expressão. Nossos resultados apresentados neste trabalho demonstraram que a hipóxia é capaz de modular positivamente a expressão de galectina-3, tanto em câmara de hipóxia quanto em cloreto cobaltoso, composto químico capaz de mimetizar a hipóxia, apresentando aumento de expressão de galectina-3 em meio completo ou privado de soro fetal bovino, mimetizando ambientes necróticos com pouco oxigênio e nutrientes. Além disso, foi demonstrado que a regulação da expressão gênica de galectina-3 in vitro e in vivo não é realizada pela metilação de seu promotor. Ensaios utilizando a técnica de interferência por RNA demonstraram que o knockdown de galectina-3, em situação in vitro com privação de oxigênio e nutrientes, induziu aumento das taxas de morte celular. Estes dados podem indicar também que a galectina-3 protege as células tumorais dentro de ambientes necróticos em glioblastomas, criando as áreas de pseudopaliçada. Em conclusão, estes experimentos demonstram as propriedades da galectina-3 de proteção contra a morte em privação de oxigênio e nutrientes, comuns dentro de tumores, destacando sua importância como alvo para agentes anti-neoplásicos.
Abstract: Gliomas are primary Central Nervous System tumors. Among them, glioblastomas are the most common clinical forms and have the worst prognosis. In an attempt to understand glioma biology, the NG97 cell line was established. This cell line presents glioblastoma's characteristics, showing nuclear atipia and high growth rate. Recently, it was discovered that this is a human-murine hybrid cell line derived from the fusion between human astrocytoma and murine stroma cells that likely occurred in the process of cell line establishment. The cell line was therefore renamed NG97ht. This cell line grows as tumors in immunodeficient mice displaying histopathological characteristics of pseudopalisades commonly seen in glioblastomas. These areas are comprised by hypercellular regions in the edge of necrotic environments and are possibly constituted by actively migrating cells out of necrotic/hypoxic environments. Besides, these pseudopalisades show the expression of molecules related to adaptation to oxygen deprivation, like Hypoxia Inducible Factor (HIF), which is involved in cell survival through the induction of many genes. Also, it has been shown that under hypoxia, galectin-3 production is stimulated, a protein involved in diverse cellular processes and that is only present in these pseudopalisades in glioblastomas, not being detected in its adjacent areas. Galectin-3 is a lectin that binds to beta-galactosides and is related to increased motility, adhesion, tumor growth and progression. Also, studies describe that galectin-3 expression is related to its promoter methylation degree in some tumor types. Our results presented here demonstrated that assays performed in hypoxic chamber and in a chemical condition mimicking hypoxia (incubation with cobaltous chloride) showed galectin-3 induction in either complete medium or deprived of fetal bovine serum, mimicking tumor's necrotic areas deprived of oxygen and nutrients. Besides, it was demonstrated that galectin-3 modulation in vitro and in vivo is not due to promoter methylation. Tests related to galectin-3 knockdown in oxygen and nutrient deprivation demonstrated that this protein has a key role in protection against cell death. It is possible that these results may indicate that galectin-3 can also protect tumor cells inside glioblastoma's necrotic areas, acting as a survival factor in disadvantageous environments with low concentrations of oxygen and nutrients. In conclusion, these experiments demonstrate galectin-3 properties related to protection against cell death in environments deprived of oxygen and nutrients, commonly found inside tumors, highlighting its importance as a target to antineoplastic agents.
Mestrado
Imunologia
Mestre em Genética e Biologia Molecular