RESUMEN

BACKGROUND: Gliomas are highly invasive brain neoplasms. MRI is the most important tool to diagnose and monitor glioma but has shortcomings. In particular, the assessment of tumor cell invasion is insufficient. This is a clinical dilemma, as recurrence can arise from MRI-occult glioma cell invasion. HYPOTHESIS: Tumor cell invasion, tumor growth and radiotherapy alter the brain parenchymal microstructure and thus are assessable by diffusion tensor imaging (DTI) and MR elastography (MRE). STUDY TYPE: Experimental, animal model. ANIMAL MODEL: Twenty-three male NMRI nude mice orthotopically implanted with S24 patient-derived glioma cells (experimental mice) and 9 NMRI nude mice stereotactically injected with 1 µL PBS (sham-injected mice). FIELD STRENGTH/SEQUENCE: 2D and 3D T2-weighted rapid acquisition with refocused echoes (RARE), 2D echo planar imaging (EPI) DTI, 2D multi-slice multi-echo (MSME) T2 relaxometry, 3D MSME MRE at 900 Hz acquired at 9.4 T (675 mT/m gradient strength). ASSESSMENT: Longitudinal 4-weekly imaging was performed for up to 4 months. Tumor volume was assessed in experimental mice (n = 10 treatment-control, n = 13 radiotherapy). The radiotherapy subgroup and 5 sham-injected mice underwent irradiation (3 × 6 Gy) 9 weeks post-implantation/sham injection. MRI-/MRE-parameters were assessed in the corpus callosum and tumor core/injection tract. Imaging data were correlated to light sheet microscopy (LSM) and histology. STATISTICAL TESTS: Paired and unpaired t-tests, a P-value ≤0.05 was considered significant. RESULTS: From week 4 to 8, a significant callosal stiffening (4.44 ± 0.22 vs. 5.31 ± 0.29 kPa) was detected correlating with LSM-proven tumor cell invasion. This was occult to all other imaging metrics. Histologically proven tissue destruction in the tumor core led to an increased T2 relaxation time (41.65 ± 0.34 vs. 44.83 ± 0.66 msec) and ADC (610.2 ± 12.27 vs. 711.2 ± 13.42 × 10-6 mm2/s) and a softening (5.51 ± 0.30 vs. 4.24 ± 0.29 kPa) from week 8 to 12. Radiotherapy slowed tumor progression. DATA CONCLUSION: MRE is promising for the assessment of key glioma characteristics. EVIDENCE LEVEL: NA TECHNICAL EFFICACY: Stage 2.

RESUMEN

BACKGROUND: Gliomas differ from meningiomas in their margins, most of which are not separated from the surrounding tissue by a distinct interface. PURPOSE: To characterize the margins of gliomas quantitatively based on the margin sharpness coefficient (MSC) is significant for clinical judgment and invasive analysis of gliomas. MATERIAL AND METHODS: The data for this study used magnetic resonance image (MRI) data from 67 local patients and 15 open patients to quantify the intensity of changes in the glioma margins of the brain using MSC. The accuracy of MSC was assessed by consistency analysis and Bland-Altman test analysis, as well as invasive correlations using receiver operating characteristic (ROC) and Spearman correlation coefficients for subjects. RESULTS: In grading the tumors, the mean MSC values were significantly lower for high-grade gliomas (HGG) than for low-grade gliomas (LGG). The concordance correlation between the measured gradient and the actual gradient was high (HGG: 0.981; LGG: 0.993), and the Bland-Altman mean difference at the 95% confidence interval (HGG: -0.576; LGG: 0.254) and the limits of concordance (HGG: 5.580; LGG: 5.436) indicated no statistical difference. The correlation between MSC and invasion based on the margins of gliomas showed an AUC of 0.903 and 0.911 for HGG and LGG, respectively. The mean Spearman correlation coefficient of the MSC versus the actual distance of invasion was -0.631 in gliomas. CONCLUSION: The relatively low MSC on the blurred margins and irregular shape of gliomas may help in benign-malignant differentiation and invasion prediction of gliomas and has potential application for clinical judgment.

Asunto(s)

Neoplasias Encefálicas , Glioma , Imagen por Resonancia Magnética , Humanos , Glioma/diagnóstico por imagen , Glioma/patología , Imagen por Resonancia Magnética/métodos , Femenino , Masculino , Persona de Mediana Edad , Neoplasias Encefálicas/diagnóstico por imagen , Neoplasias Encefálicas/patología , Adulto , Anciano , Clasificación del Tumor , Adulto Joven , Adolescente , Estudios Retrospectivos , Anciano de 80 o más Años

RESUMEN

Malignant gliomas are notoriously invasive, a major impediment against their successful treatment. This invasive growth has motivated the use of predictive partial differential equation models, formulated at varying levels of detail, and including (i) "proliferation-infiltration" models, (ii) "go-or-grow" models, and (iii) anisotropic diffusion models. Often, these models use macroscopic observations of a diffuse tumour interface to motivate a phenomenological description of invasion, rather than performing a detailed and mechanistic modelling of glioma cell invasion processes. Here we close this gap. Based on experiments that support an important role played by long cellular protrusions, termed tumour microtubes, we formulate a new model for microtube-driven glioma invasion. In particular, we model a population of tumour cells that extend tissue-infiltrating microtubes. Mitosis leads to new nuclei that migrate along the microtubes and settle elsewhere. A combination of steady state analysis and numerical simulation is employed to show that the model can predict an expanding tumour, with travelling wave solutions led by microtube dynamics. A sequence of scaling arguments allows us reduce the detailed model into simpler formulations, including models falling into each of the general classes (i), (ii), and (iii) above. This analysis allows us to clearly identify the assumptions under which these various models can be a posteriori justified in the context of microtube-driven glioma invasion. Numerical simulations are used to compare the various model classes and we discuss their advantages and disadvantages.

Asunto(s)

Glioma , Humanos , Anisotropía , Simulación por Computador , Difusión , Viaje

RESUMEN

In recent years, tissue clearing has revolutionized the way we view biological materials. This has resulted in considerable advances in neuropathology and brain imaging. Its application to gliomas has the potential to increase understanding of tumor architecture, reveal mechanisms of tumor invasion, and provide valuable insights into diagnostics and treatments. This review outlines numerous tissue-clearing applications and recent developments in glioma research and delineates the limitations of existing technology and potential applications in experimental and clinical oncology.

Asunto(s)

Neoplasias Encefálicas , Glioma , Humanos , Neoplasias Encefálicas/diagnóstico por imagen , Neoplasias Encefálicas/patología , Glioma/diagnóstico por imagen , Glioma/patología , Encéfalo/patología , Imagenología Tridimensional , Microambiente Tumoral

RESUMEN

This work shows that the longitudinal relaxation differences observed at very low magnetic fields between invasion/migration and proliferation processes on glioma mouse models in vivo are related to differences in the transmembrane water exchange basically linked to the aquaporin expression changes. Three glioma mouse models were used: Glio6 and Glio96 as invasion/migration models and U87 as cell proliferation model. In vivo proton longitudinal relaxation-rate constants (R1) at very low fields were measured by fast field cycling NMR (FFC-NMR). The tumor contribution to the observed proton relaxation rate, R1tum (U87: 12.26 ± 0.64 s−1; Glio6: 3.76 ± 0.88 s−1; Glio96: 6.90 ± 0.64 s−1 at 0.01 MHz), and the intracellular water lifetime, τin (U87: 826 ± 19 ms; Glio6: 516 ± 8 ms; Glio96: 596 ± 15 ms), were found to be good diagnostic hallmarks to distinguish invasion/migration from proliferation (p < 0.01 and 0.001). Overexpression of AQP4 and AQP1 were assessed in invasion/migration models, highlighting the pathophysiological role of these two aquaporins in water exchange that, in turn, determine the lower values in the observed R1 relaxation rate constant in glioma invasion/migration. Overall, our findings demonstrate that τin and R1 (measured at very low fields) are relevant biomarkers, discriminating invasion/migration from proliferation in vivo. These results highlight the use of FFC-NMR and FFC-imaging to assess the efficiency of drugs that could modulate aquaporin functions.

RESUMEN

BACKGROUND: Tumor invasion, a hallmark of malignant gliomas, involves reorganization of cell polarity and changes in the expression and distribution of scaffolding proteins associated with polarity complexes. The scaffolding proteins of the DLG family are usually downregulated in invasive tumors and regarded as tumor suppressors. Despite their important role in regulating neurodevelopmental signaling, the expression and functions of DLG proteins have remained almost entirely unexplored in malignant gliomas. METHODS: Western blot, immunohistochemistry, and analysis of gene expression were used to quantify DLG members in glioma specimens and cancer datasets. Over-expression and knockdown of DLG5, the highest-expressed DLG member in glioblastoma, were used to investigate its effects on tumor stem cells and tumor growth. qRT-PCR, Western blotting, and co-precipitation assays were used to investigate DLG5 signaling mechanisms. RESULTS: DLG5 was upregulated in malignant gliomas compared to other solid tumors, being the predominant DLG member in all glioblastoma molecular subtypes. DLG5 promoted glioblastoma stem cell invasion, viability, and self-renewal. Knockdown of this protein in vivo disrupted tumor formation and extended survival. At the molecular level, DLG5 regulated Sonic Hedgehog (Shh) signaling, making DLG5-deficient cells insensitive to Shh ligand. Loss of DLG5 increased the proteasomal degradation of Gli1, underlying the loss of Shh signaling and tumor stem cell sensitization. CONCLUSIONS: The high expression and pro-tumoral functions of DLG5 in glioblastoma, including its dominant regulation of Shh signaling in tumor stem cells, reveal a novel role for this protein that is strikingly different from its proposed tumor-suppressor role in other solid tumors.

Asunto(s)

Glioblastoma , Glioma , Proteínas Hedgehog , Proteínas de la Membrana , Proteínas Supresoras de Tumor , Línea Celular Tumoral , Regulación Neoplásica de la Expresión Génica , Glioblastoma/patología , Glioma/patología , Proteínas Hedgehog/genética , Humanos , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Células Madre Neoplásicas/metabolismo , Factores de Transcripción/genética , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismo , Proteína con Dedos de Zinc GLI1/genética , Proteína con Dedos de Zinc GLI1/metabolismo

RESUMEN

Our objective was to study NMR relaxometry of glioma invasion/migration at very low field (<2 mT) by fast-field-cycling NMR (FFC-NMR) and to decipher the pathophysiological processes of glioma that are responsible for relaxation changes in order to open a new diagnostic method that can be extended to imaging. The phenotypes of two new glioma mouse models, Glio6 and Glio96, were characterized by T2w -MRI, HE histology, Ki-67 immunohistochemistry (IHC) and CXCR4 RT-qPCR, and were compared with the U87 model. R1 dispersions of glioma tissues were acquired at low field (0.1 mT-0.8 T) ex vivo and were fitted with Lorentzian and power-law models to extract FFC biomarkers related to the molecular dynamics of water. In order to decipher relaxation changes, three main invasion/migration pathophysiological processes were studied: hypoxia, H2 O2 function and the water-channel aquaporin-4 (AQP4). Glio6 and Glio96 were characterized with invasion/migration phenotype and U87 with high cell proliferation as a solid glioma. At very low field, invasion/migration versus proliferation was characterized by a decrease in the relaxation-rate constant (ΔR1 ≈ -32% at 0.1 mT) and correlation time (≈-40%). These decreases corroborated the AQP4-IHC overexpression (Glio6/Glio96: +92%/+46%), suggesting rapid transcytolemmal water exchange, which was confirmed by the intracellular water-lifetime τIN decrease (ΔτIN ≈ -30%). In functional experiments, AQP4 expression, τIN and the relaxation-rate constant at very low field were all found to be sensitive to hypoxia and to H2 O2 stimuli. At very low field the role of water exchanges in relaxation modulation was confirmed, and for the first time it was linked to the glioma invasion/migration and to its main pathophysiological processes: hypoxia, H2 O2 redox signaling and AQP4 expression. The method appears appropriate to evaluate the effect of drugs that can target these pathophysiological mechanisms. Finally, FFC-NMR operating at low field is demonstrated to be sensitive to invasion glioma phenotype and can be straightforwardly extended to FFC-MRI as a new cancer invasion imaging method in the clinic.

Asunto(s)

Glioma , Agua , Animales , Biomarcadores , Movimiento Celular , Glioma/patología , Hipoxia , Campos Magnéticos , Imagen por Resonancia Magnética/métodos , Ratones , Simulación de Dinámica Molecular

RESUMEN

Gliomas are the most common and fatal brain tumors worldwide. Abnormal DNA promoter methylation is an important mechanism for gene loss of tumor suppressors. A long non-coding RNA colorectal adenocarcinoma hypermethylated (CAHM) has been reported to be nearly deleted in glioblastomas (GBMs). Nevertheless, the roles of CAHM in gliomas remain unknown up to now. In the present study, 969 glioma samples downloaded from the CGGA and Gravendeel databases were included. We found that CAHM expression was correlated with glioma grades, molecular subtype, IDH mutation status, and 1q/19p codel status. In glioma cells, CAHM is hypermethylated by DNA methyltransferase1 (DNMT1) and the loss of CAHM expression could be reversed by 5-Aza-2'-deoxycytidine (5-Aza), a specific inhibitor of DNA methyltransferases. Besides, the expression of CAHM was negatively associated with overall survival in both primary and recurrent gliomas. Moreover, the result of Gene Ontology (GO) analysis suggested that CAHM participated in negatively regulating cell development, nervous system development, neurogenesis, and integrin-mediated signaling pathway. Overexpression of CAHM inhibited glioma cell proliferation, clone formation, and invasion. Further exploring results showed that CAHM overexpression suppressed glioma migration and invasion through SPAK/MAPK pathway. Collectively, this study disclosed that CAHM might be a suppressor in gliomas.

Asunto(s)

Adenocarcinoma , Neoplasias Encefálicas , Neoplasias Colorrectales , Glioma , ARN Largo no Codificante , Adenocarcinoma/genética , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patología , Línea Celular Tumoral , Proliferación Celular/genética , Neoplasias Colorrectales/genética , ADN , ADN (Citosina-5-)-Metiltransferasa 1 , Metilación de ADN/genética , Metilasas de Modificación del ADN , Decitabina , Regulación Neoplásica de la Expresión Génica , Glioma/genética , Glioma/patología , Humanos , Integrinas/genética , Sistema de Señalización de MAP Quinasas , ARN Largo no Codificante/genética

RESUMEN

Glioblastoma (GBM) possesses glioma stem cells (GSCs) that exhibit aggressive invasion behavior in the brain. Current preclinical GBM invasion assays using mouse brain xenografts are time consuming and less efficient. Here, we demonstrate an array of methods that allow rapid and efficient assaying of GSCs invasion in human brain organoids. The assays are versatile to characterize various aspects of GSCs, such as invasion, integration, and interaction with mature neurons of brain organoids. Tissue clearing and quantitative 3D imaging of GSCs in host organoids reveal that invasiveness is inversely correlated with the organoids' age. Importantly, the described invasion assays can distinguish the invasive behaviors of primary and recurrent GSCs. The assays are also amenable to test pharmacological agents. As an example, we show that GI254023X, an inhibitor of ADAM10, could prevent the integration of GSCs into the organoids.

Asunto(s)

Encéfalo/fisiopatología , Glioblastoma/fisiopatología , Organoides/fisiopatología , Humanos

RESUMEN

Widespread tumor cell invasion is a fundamental property of diffuse gliomas and is ultimately responsible for their poor prognosis. A greater understanding of basic mechanisms underlying glioma invasion is needed to provide insights into therapies that could potentially counteract them. While none of the currently available in vitro models can fully recapitulate the complex interactions of glioma cells within the brain tumor microenvironment, if chosen and developed appropriately, these models can provide controlled experimental settings to study molecular and cellular phenomena that are challenging or impossible to model in vivo. Therefore, selecting the most appropriate in vitro model, together with its inherent advantages and limitations, for specific hypotheses and experimental questions achieves primary significance. In this review, we describe and discuss commonly used methods for modeling and studying glioma invasion in vitro, including platforms, matrices, cell culture, and visualization techniques, so that choices for experimental approach are informed and optimal.

Asunto(s)

Neoplasias Encefálicas , Glioma , Encéfalo , Humanos , Invasividad Neoplásica , Microambiente Tumoral

RESUMEN

Diffuse brain invasion by glioma cells prevents effective surgical or molecular-targeted therapy and underlies a detrimental outcome. Migrating glioma cells are guided by complex anatomical brain structures but the exact mechanisms remain poorly defined. To identify adhesion receptor systems and matrix structures supporting glioma cell invasion into brain-like environments we used 2D and 3D organotypic invasion assays in combination with antibody-, peptide- and RNA-based interference. Combined interference with ß1 and αV integrins abolished the migration of U-251 and E-98 glioma cells on reconstituted basement membrane; however, invasion into primary brain slices or 3D astrocyte-based scaffolds and migration on astrocyte-deposited matrix was only partly inhibited. Any residual invasion was supported by vascular structures, as well as laminin 511, a central constituent of basement membrane of brain blood vessels. Multi-targeted interference against ß1, αV and α6 integrins expressed by U-251 and E-98 cells proved insufficient to achieve complete migration arrest. These data suggest that mechanocoupling by integrins is relatively resistant to antibody- or peptide-based targeting, and cooperates with additional, as yet unidentified adhesion systems in mediating glioma cell invasion in complex brain stroma.

Asunto(s)

Glioma/metabolismo , Animales , Astrocitos/citología , Astrocitos/metabolismo , Membrana Basal/metabolismo , Línea Celular Tumoral , Movimiento Celular/fisiología , Citometría de Flujo , Técnica del Anticuerpo Fluorescente , Glioma/patología , Técnicas In Vitro , Integrina alfa3/metabolismo , Integrinas/metabolismo , Laminina/metabolismo , Espectrometría de Masas , Ratones

RESUMEN

Glioblastoma multiforme is the most common brain tumor in adults. Because of its highly invasive nature, it is not easy to treat, resulting in high mortality rates. Stromal interacting molecule 1 (Stim1) plays important roles in regulating store-operated Ca2+ entry, and controls invasion by cancer cells. However, the mechanisms and functions of Stim1 in glioma progression are still unclear. In this study, we investigated the effects of targeting Stim1 expression on glioma cell invasion. By analyzing profiles of glioblastoma multiforme patients from RNA-sequencing data in The Cancer Genome Atlas, higher expression levels of STIM1 were correlated with the poor survival. Furthermore, signaling pathways associated with tumor malignancy, including the epithelial-to-mesenchymal transition (EMT), were activated in patients with high STIM1 expression according to gene set enrichment analyses. Higher Stim1 levels were found in glioma cells compared to human astrocytes, and these higher levels enhanced glioma cell invasion. Xanthohumol (XN), a prenylated flavonoid extracted from the hop plant Humulus lupulus L. (Cannabaceae), significantly reduced cell invasion through inhibiting Stim1 expression. From an micro(mi)RNA array analysis, miR-4725-3p was up-regulated by XN treatment. Over-expression of miR-4725-3p inhibited glioma cell invasion via directly targeting the 3'-untranslated region of STIM1. The extracellular signal-regulated kinase/c-Fos pathway was also validated to participate in XN-up-regulated miR-4725-3p expression according to promoter and chromatin immunoprecipitation assays. These results emphasize that miR-4725-3p-inhibited STIM1 signaling is involved in XN-attenuated glioma cell invasion. These findings may provide insights into novel therapeutic strategies for future glioblastoma therapy and drug development. Open Data: Materials are available on https://cos.io/our-services/open-science-badges/ https://osf.io/93n6m/.

Asunto(s)

Antineoplásicos/farmacología , Flavonoides/farmacología , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Glioblastoma/patología , MicroARNs/metabolismo , Proteínas de Neoplasias/metabolismo , Propiofenonas/farmacología , Transducción de Señal/efectos de los fármacos , Molécula de Interacción Estromal 1/metabolismo , Anciano , Anciano de 80 o más Años , Línea Celular Tumoral , Inmunoprecipitación de Cromatina , Colágeno , Combinación de Medicamentos , Femenino , Humanos , Laminina , Masculino , MicroARNs/genética , Persona de Mediana Edad , Mutagénesis/efectos de los fármacos , Mutagénesis/genética , Invasividad Neoplásica , Proteínas de Neoplasias/genética , Regiones Promotoras Genéticas/genética , Proteoglicanos , Proteínas Proto-Oncogénicas c-fos/genética , Proteínas Proto-Oncogénicas c-fos/metabolismo , ARN Mensajero/metabolismo , Molécula de Interacción Estromal 1/genética

RESUMEN

Glioblastoma are notorious for their highly invasive growth, diffusely infiltrating adjacent brain structures that precludes complete resection, and is a major obstacle for cure. To characterize this "invisible" tumor part, we designed a high resolution multimodal imaging approach assessing in vivo the metabolism of invasively growing glioma xenografts in the mouse brain. Animals were subjected longitudinally to magnetic resonance imaging (MRI) and 1 H spectroscopy (MRS) at ultra high field (14.1 Tesla) that allowed the measurement of 16 metabolic biomarkers to characterize the metabolic profiles. As expected, the neuronal functionality was progressively compromised as indicated by decreasing N-acetyl aspartate, glutamate and gamma-aminobutyric acid and reduced neuronal TCA cycle (-58%) and neurotransmission (-50%). The dynamic metabolic changes observed, captured differences in invasive growth that was modulated by re-expression of the tumor suppressor gene WNT inhibitory factor 1 (WIF1) in the orthotopic xenografts that attenuates invasion. At late stage mice were subjected to 13 C MRS with infusion of [1,6-13 C]glucose and 18 FDG positron emission tomography (PET) to quantify cell-specific metabolic fluxes involved in glucose metabolism. Most interestingly, this provided the first in vivo evidence for significant glucose oxidation in glioma cells. This suggests that the infiltrative front of glioma does not undergo the glycolytic switch per se, but that environmental triggers may induce metabolic reprograming of tumor cells.

Asunto(s)

Proteínas Adaptadoras Transductoras de Señales/genética , Neoplasias Encefálicas/diagnóstico por imagen , Encéfalo/metabolismo , Fluorodesoxiglucosa F18/metabolismo , Glioma/diagnóstico por imagen , Glucosa/metabolismo , Proteínas Represoras/genética , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Animales , Ácido Aspártico/análogos & derivados , Ácido Aspártico/metabolismo , Encéfalo/diagnóstico por imagen , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , Línea Celular Tumoral , Glioma/genética , Glioma/metabolismo , Ácido Glutámico/metabolismo , Humanos , Masculino , Ratones , Trasplante de Neoplasias , Oxidación-Reducción , Tomografía de Emisión de Positrones/métodos , Espectroscopía de Protones por Resonancia Magnética/métodos , Proteínas Represoras/metabolismo , Ácido gamma-Aminobutírico/metabolismo

RESUMEN

Malignant gliomas are primary tumors of the central nervous system characterized by diffuse infiltration into the brain and a high recurrence rate. Advances in comprehensive genomic studies have provided unprecedented insight into the genetic and molecular heterogeneity of these tumors and refined our understanding of their evolution from low to high grade. However, similar levels of phenotypic characterization are indispensable to understanding the complexity of malignant gliomas. Experimental glioma models have also achieved great progress in recent years. Advances in transgenic technologies and cell culture have allowed the establishment of mouse models that mirror the human disease with increasing fidelity and which support single-cell resolution for phenotypic analyses. Here we review the major types of preclinical glioma models, with an emphasis on how recent developments in experimental modeling have shed new light on two fundamental aspects of glioma phenotype, their cell of origin and their invasive potential.

Asunto(s)

Neoplasias Encefálicas/patología , Glioma/patología , Animales , Humanos , Ratones , Ratones Transgénicos , Invasividad Neoplásica , Trasplante de Neoplasias , Análisis de la Célula Individual

RESUMEN

Adult gliomas are aggressive brain tumours associated with low patient survival rates and limited life expectancy. The most important hallmark of this type of tumour is its invasive behaviour, characterized by a markedly phenotypic plasticity, infiltrative tumour morphologies and the ability of malignant progression from low- to high-grade tumour types. Indeed, the widespread infiltration of healthy brain tissue by glioma cells is largely responsible for poor prognosis and the difficulty of finding curative therapies. Meanwhile, mathematical models have been established to analyse potential mechanisms of glioma invasion. In this review, we start with a brief introduction to current biological knowledge about glioma invasion, and then critically review and highlight future challenges for mathematical models of glioma invasion.

Asunto(s)

Neoplasias Encefálicas , Encéfalo , Glioma , Modelos Biológicos , Encéfalo/metabolismo , Encéfalo/patología , Encéfalo/fisiopatología , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patología , Neoplasias Encefálicas/fisiopatología , Glioma/metabolismo , Glioma/patología , Glioma/fisiopatología , Humanos , Invasividad Neoplásica

RESUMEN

Diffuse invasion of glioma cells into the brain parenchyma leads to nonresectable brain tumors and poor prognosis of glioma disease. In vivo, glioma cells can adopt a range of invasion strategies and routes, by moving as single cells, collective strands and multicellular networks along perivascular, perineuronal and interstitial guidance cues. Current in vitro assays to probe glioma cell invasion, however, are limited in recapitulating the modes and adaptability of glioma invasion observed in brain parenchyma, including collective behaviours. To mimic in vivo-like glioma cell invasion in vitro, we here applied three tissue-inspired 3D environments combining multicellular glioma spheroids and reconstituted microanatomic features of vascular and interstitial brain structures. Radial migration from multicellular glioma spheroids of human cell lines and patient-derived xenograft cells was monitored using (1) reconstituted basement membrane/hyaluronan interfaces representing the space along brain vessels; (2) 3D scaffolds generated by multi-layered mouse astrocytes to reflect brain interstitium; and (3) freshly isolated mouse brain slice culture ex vivo. The invasion patterns in vitro were validated using histological analysis of brain sections from glioblastoma patients and glioma xenografts infiltrating the mouse brain. Each 3D assay recapitulated distinct aspects of major glioma invasion patterns identified in mouse xenografts and patient brain samples, including individually migrating cells, collective strands extending along blood vessels, and multicellular networks of interconnected glioma cells infiltrating the neuropil. In conjunction, these organotypic assays enable a range of invasion modes used by glioma cells and will be applicable for mechanistic analysis and targeting of glioma cell dissemination.

Asunto(s)

Astrocitos/patología , Vasos Sanguíneos/patología , Neoplasias Encefálicas/patología , Glioma/patología , Esferoides Celulares/patología , Animales , Humanos , Ratones , Células Tumorales Cultivadas

RESUMEN

The p75 neurotrophin receptor (p75NTR, a.k.a. CD271), a transmembrane glycoprotein and a member of the tumor necrosis family (TNF) of receptors, was originally identified as a nerve growth factor receptor in the mid-1980s. While p75NTR is recognized to have important roles during neural development, its presence in both neural and nonneural tissues clearly supports the potential to mediate a broad range of functions depending on cellular context. Using an unbiased in vivo selection paradigm for genes underlying the invasive behavior of glioma, a critical characteristic that contributes to poor clinical outcome for glioma patients, we identified p75NTR as a central regulator of glioma invasion. Herein we review the expanding role that p75NTR plays in glioma progression with an emphasis on how p75NTR may contribute to the treatment refractory nature of glioma. Based on the observation that p75NTR is expressed and functional in two critical glioma disease reservoirs, namely, the highly infiltrative cells that evade surgical resection, and the radiation- and chemotherapy-resistant brain tumor-initiating cells (also referred to as brain tumor stem cells), we propose that p75NTR and its myriad of downstream signaling effectors represent rationale therapeutic targets for this devastating disease. Lastly, we provide the provocative hypothesis that, in addition to the well-documented cell autonomous signaling functions, the neurotrophins, and their respective receptors, contribute in a cell nonautonomous manner to drive the complex cellular and molecular composition of the brain tumor microenvironment, an environment that fuels tumorigenesis.

Asunto(s)

Carcinogénesis/metabolismo , Glioma/metabolismo , Modelos Neurológicos , Factores de Crecimiento Nervioso/metabolismo , Proteínas del Tejido Nervioso/agonistas , Receptores de Factor de Crecimiento Nervioso/agonistas , Transducción de Señal , Animales , Antineoplásicos/uso terapéutico , Carcinogénesis/patología , Resistencia a Antineoplásicos , Glioma/tratamiento farmacológico , Glioma/inmunología , Glioma/patología , Humanos , Macrófagos/citología , Macrófagos/inmunología , Macrófagos/metabolismo , Macrófagos/patología , Microglía/citología , Microglía/inmunología , Microglía/metabolismo , Microglía/patología , Invasividad Neoplásica , Proteínas de Neoplasias/agonistas , Proteínas de Neoplasias/metabolismo , Células Madre Neoplásicas/inmunología , Células Madre Neoplásicas/metabolismo , Células Madre Neoplásicas/patología , Proteínas del Tejido Nervioso/metabolismo , Células-Madre Neurales/citología , Células-Madre Neurales/inmunología , Células-Madre Neurales/metabolismo , Células-Madre Neurales/patología , Receptores de Factor de Crecimiento Nervioso/metabolismo , Transducción de Señal/efectos de los fármacos , Microambiente Tumoral/efectos de los fármacos

RESUMEN

Malignant gliomas are devastating tumors, frequently killing those diagnosed in little over a year. The profuse infiltration of glioma cells into healthy tissue surrounding the main tumor mass is one of the major obstacles limiting the improvement of patient survival. Migration along the abluminal side of blood vessels is one of the salient features of glioma cell invasion. Invading glioma cells are attracted to the vascular network, in part by the neuropeptide bradykinin, where glioma cells actively modify the gliovascular interface and undergo volumetric alterations to navigate the confined space. Critical to these volume modifications is a proposed hydrodynamic model that involves the flux of ions in and out of the cell, followed by osmotically obligated water. Ion and water channels expressed by the glioma cell are essential in this model of invasion and make opportune therapeutic targets. Lastly, there is growing evidence that vascular-associated glioma cells are able to control the vascular tone, presumably to free up space for invasion and growth. The unique mechanisms that enable perivascular glioma invasion may offer critical targets for therapeutic intervention in this devastating disease. Indeed, a chloride channel-blocking peptide has already been successfully tested in human clinical trials.

Asunto(s)

Vasos Sanguíneos/patología , Glioma/metabolismo , Glioma/patología , Canales Iónicos/metabolismo , Animales , Transporte Biológico , Tamaño de la Célula , Glioma/irrigación sanguínea , Humanos , Invasividad Neoplásica

RESUMEN

Autophagy is a tightly regulated process activated in response to metabolic stress and other microenvironmental changes. Astrocyte elevated gene 1 (AEG-1) reportedly induces protective autophagy. Our results indicate that AEG-1 also enhances the susceptibility of malignant glioma cells to TGF-ß1-triggered epithelial-mesenchymal transition (EMT) through induction of autophagy. TGF-ß1 induced autophagy and activated AEG-1 via Smad2/3 phosphorylation in malignant glioma cells. Also increased was oncogene cyclin D1 and EMT markers, which promoted tumor progression. Inhibition of autophagy using siRNA-BECN1 and siRNA-AEG-1 suppressed EMT. In tumor samples from patients with malignant glioma, immunohistochemical assays showed that expression levels of TGF-ß1, AEG-1, and markers of autophagy and EMT, all gradually increase with glioblastoma progression. In vivo siRNA-AEG-1 administration to rats implanted with C6 glioma cells inhibited tumor growth and increased the incidence of apoptosis among tumor cells. These findings shed light on the mechanisms underlying the invasiveness and progression of malignant gliomas.

Asunto(s)

Neoplasias Encefálicas/patología , Moléculas de Adhesión Celular/metabolismo , Transición Epitelial-Mesenquimal/fisiología , Glioma/patología , Factor de Crecimiento Transformador beta1/metabolismo , Animales , Autofagia , Neoplasias Encefálicas/metabolismo , Línea Celular Tumoral , Femenino , Glioma/metabolismo , Humanos , Masculino , Proteínas de la Membrana , Proteínas de Unión al ARN , Ratas , Ratas Sprague-Dawley

RESUMEN

Glioma is a common type of primary brain tumour, with a strongly invasive potential, often exhibiting non-uniform, highly irregular growth. This makes it difficult to assess the degree of extent of the tumour, hence bringing about a supplementary challenge for the treatment. It is therefore necessary to understand the migratory behaviour of glioma in greater detail. In this paper, we propose a multiscale model for glioma growth and migration. Our model couples the microscale dynamics (reduced to the binding of surface receptors to the surrounding tissue) with a kinetic transport equation for the cell density on the mesoscopic level of individual cells. On the latter scale, we also include the proliferation of tumour cells via effects of interaction with the tissue. An adequate parabolic scaling yields a convection-diffusion-reaction equation, for which the coefficients can be explicitly determined from the information about the tissue obtained by diffusion tensor imaging (DTI). Numerical simulations relying on DTI measurements confirm the biological findings that glioma spread along white matter tracts.

Asunto(s)

Neoplasias Encefálicas/patología , Imagen de Difusión Tensora , Glioma/patología , Modelos Teóricos , Neoplasias Encefálicas/diagnóstico por imagen , Glioma/diagnóstico por imagen , Humanos