Decrease in Fas-induced apoptosis by the γ-secretase inhibitor is dependent on p75(NTR) in a glioblastoma cell line.

International audiencep75(NTR), a member of the tumor necrosis factor superfamily, plays a key role in numerous physiological processes, including cell survival or apoptosis. Yet, the associated signaling pathways remain poorly understood. Similar to Notch, γ-secretase cleavage is implicated in the p75(NTR) signaling pathway leading to nuclear translocation of the intracellular domain and cell death. Fas receptor activation was found to promote cell death apoptosis in several cell lines. The goal of this study was to determine the respective role of p75(NTR) and Notch in the resistance to Fas-induced apoptosis in the U-87 MG glioblastoma cell line. Using the γ-secretase inhibitor, we investigated the modulation of Fas-induced apoptosis dependent on p75(NTR)-Fas receptor interaction. Whereas the U-87 MG cells expressed the Fas receptor at the cell membrane, apoptosis induced by Fas activation was decreased by the γ-secretase inhibitor. These data suggest that γ-secretase is implicated in p75(NTR) and Fas interaction leading to cell death signaling

Experimental methods in chemical engineering: Scanning electron microscopy and X-ray ultra-microscopy—SEM and XuM

Scanning electron microscopy (SEM) produces images at 500 000 times magnification and better than 1 nm resolution to characterize inorganic and organic solid morphology, surface topography, and crystallography. An electron beam interacts with the material and generates secondary electrons (SE) and backscattered electrons (BSE) that detectors capture. Coupled with X-ray energy-dispersive spectroscopy (X-EDS), SEM-EDS identifies elemental composition. X-ray ultra-microscopy (XuM) traverses particles to identify phase changes and areas of high density and voids without slicing through the solids by microtome. Although SEM instrument capability continuously evolves with higher magnification and better resolution, desktop SEMs are becoming standard in laboratories that require frequent imaging and lower magnification. Hand-held cameras (800–1500×) have the advantage of low cost, ease of use, and better colours. SEM depth of field is better than visible light microscopy, but image stacking software has narrowed the gap between the two. Modern user interfaces mean that today's SEM instruments are easier to operate and data acquisition is faster, but operators must be able to select the right technique for the application (e.g., SE vs. BSE). Furthermore, they must understand how operating parameters like probe current, accelerating voltage, spot-diameter, convergence angle, and working distance compromise sample integrity. The number of articles the Web of Science indexes that mention SEM has grown from 1000 in 1990 to over 40 000 in 2021. A bibliometric map identified four clusters of research: mechanical properties and microstructure; nanoparticles, composites, and graphene; antibacterial and green synthesis; and adsorption and wastewater

Clinical Relevance of Tumor Cells with Stem-Like Properties in Pediatric Brain Tumors

BACKGROUND: Primitive brain tumors are the leading cause of cancer-related death in children. Tumor cells with stem-like properties (TSCs), thought to account for tumorigenesis and therapeutic resistance, have been isolated from high-grade gliomas in adults. Whether TSCs are a common component of pediatric brain tumors and are of clinical relevance remains to be determined. METHODOLOGY/PRINCIPAL FINDINGS: Tumor cells with self-renewal properties were isolated with cell biology techniques from a majority of 55 pediatric brain tumors samples, regardless of their histopathologies and grades of malignancy (57% of embryonal tumors, 57% of low-grade gliomas and neuro-glial tumors, 70% of ependymomas, 91% of high-grade gliomas). Most high-grade glioma-derived oncospheres (10/12) sustained long-term self-renewal akin to neural stem cells (>7 self-renewals), whereas cells with limited renewing abilities akin to neural progenitors dominated in all other tumors. Regardless of tumor entities, the young age group was associated with self-renewal properties akin to neural stem cells (P = 0.05, chi-square test). Survival analysis of the cohort showed an association between isolation of cells with long-term self-renewal abilities and a higher patient mortality rate (P = 0.013, log-rank test). Sampling of low- and high-grade glioma cultures showed that self-renewing cells forming oncospheres shared a molecular profile comprising embryonic and neural stem cell markers. Further characterization performed on subsets of high-grade gliomas and one low-grade glioma culture showed combination of this profile with mesenchymal markers, the radio-chemoresistance of the cells and the formation of aggressive tumors after intracerebral grafting. CONCLUSIONS/SIGNIFICANCE: In brain tumors affecting adult patients, TSCs have been isolated only from high-grade gliomas. In contrast, our data show that tumor cells with stem cell-like or progenitor-like properties can be isolated from a wide range of histological sub-types and grades of pediatric brain tumors. They suggest that cellular mechanisms fueling tumor development differ between adult and pediatric brain tumors

Clinical management of molecular alterations identified by high throughput sequencing in patients with advanced solid tumors in treatment failure: Real-world data from a French hospital

BackgroundIn the context of personalized medicine, screening patients to identify targetable molecular alterations is essential for therapeutic decisions such as inclusion in clinical trials, early access to therapies, or compassionate treatment. The objective of this study was to determine the real-world impact of routine incorporation of FoundationOne analysis in cancers with a poor prognosis and limited treatment options, or in those progressing after at least one course of standard therapy.MethodsA FoundationOneCDx panel for solid tumor or liquid biopsy samples was offered to 204 eligible patients.ResultsSamples from 150 patients were processed for genomic testing, with a data acquisition success rate of 93%. The analysis identified 2419 gene alterations, with a median of 11 alterations per tumor (range, 0–86). The most common or likely pathogenic variants were on TP53, TERT, PI3KCA, CDKN2A/B, KRAS, CCDN1, FGF19, FGF3, and SMAD4. The median tumor mutation burden was three mutations/Mb (range, 0–117) in 143 patients with available data. Of 150 patients with known or likely pathogenic actionable alterations, 13 (8.6%) received matched targeted therapy. Sixty-nine patients underwent Molecular Tumor Board, which resulted in recommendations in 60 cases. Treatment with genotype-directed therapy had no impact on overall survival (13 months vs. 14 months; p = 0.95; hazard ratio = 1.04 (95% confidence interval, 0.48–2.26)].ConclusionsThis study highlights that an organized center with a Multidisciplinary Molecular Tumor Board and an NGS screening system can obtain satisfactory results comparable with those of large centers for including patients in clinical trials

Development of quantitative techniques for lithium compounds for next generation batteries with focused ion beam scanning electron microscopy

Electric vehicles have started to make their appearance in the transportation industry. At Quebec's scale especially, since electricity is already sustained by an extensive network of dams and reservoir, Hydro-Quebec puts a lot of focus towards green gas emission reduction via transportation electrification. To be widely accepted, batteries used in electric vehicles must have high ranges, long durability, be safe and an economical choice in the long run for its user to abandon gasoline-powered automobiles. In that matter, the company's Center of Excellence in Transportation Electrification and Energy Storage works tirelessly on the development of new generation battery materials using elements available in large quantities, with high performance chemistry. Materials characterization with Scanning Electron Microscopy is one of the most important steps in developing new materials, since it links the microstructure of the material to its fabrication process and properties down to the nanometer scale. This study focuses on the development of quantitative techniques for lithium in battery materials since this light element is the key element in the operation of a battery. In this work energy dispersive X-ray spectroscopy (EDS), electron energy-loss spectroscopy (EELS) and secondary ion mass spectrometry are evaluated in relation to their capabilities to both detect and quantify lithium atoms in battery materials. A portable time-of-flight secondary ion mass spectrometer (TOF-SIMS) that can attach to a standard dual beam microscope(FIB-SEM) was found to fulfill both aspects while allowing high resolution imaging andchemical analysis of the samples. An experimental calibration curve of lithium content in standard nickel cobalt manganese oxide cathodes was built using TOF-SIMS detector. The calibration curve allows identification of lithium content in cathodes with different state of charge and according to different charging rates. TOF-SIMS allows visualization of ionic distributions in material. Furthermore, it can help observe differences in crystallographic orientation with respect to the beam in between primary particles and permits identification of chemical hotspots of lithium.De plus en plus, les voitures électriques font leur apparition sur le marché de l'automobile. À l'échelle du Québec plus particulièrement, comme la majorité de l'électricité utilisée de façon domestique et industrielle provient d'un vaste réseaux hydroélectrique, le focus d'Hydro-Québec envers la réduction des émissions de gaz à effet de serres se tourne vers l'électrification des transports. Pour que le grand public délaisse la voiture à essence au profit de la voiture électrique, les batteries proposées dans ces véhicules doivent permettre une grande autonomie, être durables en plus d'être sécuritaires et se révéler un choix économique à long terme pour l'acheteur. Selon cette perspective, le Centre d'Excellence en Électrification des transports et Stockage d'Énergie d'Hydro-Québec s'acharne à développer des matériaux de batteries utilisant des éléments disponibles en grandes quantités et économiques en plus de d'une chimie de haute performance. La caractérisation des matériaux à l'aide d'un microscope électronique à balayage est l'une des étapes les plus importantes dans la recherche et développement, puisqu'elle peut nous indiquer à chaque étape de la vie utile d'une batterie les liens entre la microstructure, les processus de fabrication et ses propriétés et ce, jusqu'au nanomètre. Ce travail porte sur le développement de techniques quantitatives pour le lithium dans le smatériaux de batteries puisque celui-ci est l'élément clé de leur fonctionnement. Dans cette étude, les techniques de spectroscopie des rayons X par dispersion d'énergie (EDS), de spectroscopie des pertes d'énergie des électrons (EELS) et la spectrométrie de masse à ionisation secondaire (SIMS) seront évaluées par rapport à leur capacité à détecter et à quantifier le lithium dans les matériaux de batteries. Un détecteur portable d'ion secondaires par temps de vol (TOF-SIMS) s'est révélé le meilleur choix parmi ces techniques en permettant l'imagerie haute résolution du lithium et son analyse chimique et quantitative. Une courbe de calibration expérimentale du contenu en lithium dans des cathodes standard d'oxide de nickel cobalt manganese a pu être construite grâce au TOF-SIMS. Cette courbe de calibration permet l'identification de la concentration de lithium dans l'échantillon en fonction de l'état decharge de la cathode et selon différent taux de charge. Le TOF-SIMS permet de surcroît la visualisation des distributions des ions dans le matériaux. Il a permis de voir des différences dans l'orientation cristalline des grains primaires et l'identification de points chaud ou "hotspots" de lithium

Oncogramme, a new promising method for individualized breast tumour response testing for cancer treatment.

International audienceBACKGROUND:Breast cancer is the most widely spread cancer in the world, attracting much research and individualized tumour response testing (ITRT) methods are now used to individualize patient chemotherapeutic administrations. A new ITRT method was developed with optimized processing.MATERIALS AND METHODS:Breast tumour fragments were separated and the cells seeded in a foetal calf serum-free defined medium. After various chemotherapeutic treatments, cytotoxicity was determined by cell death detection with calcein acetoxymethyl and ethidium homodimer labelling.RESULTS:The culture medium allowed breast tumour cell proliferation in culture, while preventing fibroblastic cell survival. Moreover, the cell death analysis gave rise to a chemoresistance profile called an Oncogramme, with statistically significant values.CONCLUSION:The Oncogramme is a new ITRT method which can predict patient cell sensitivities to chemotherapeutics and should be validated by a new phase I clinical trial

Autophagy and Extracellular Vesicles, Connected to rabGTPase Family, Support Aggressiveness in Cancer Stem Cells

Even though cancers have been widely studied and real advances in therapeutic care have been made in the last few decades, relapses are still frequently observed, often due to therapeutic resistance. Cancer Stem Cells (CSCs) are, in part, responsible for this resistance. They are able to survive harsh conditions such as hypoxia or nutrient deprivation. Autophagy and Extracellular Vesicles (EVs) secretion are cellular processes that help CSC survival. Autophagy is a recycling process and EVs secretion is essential for cell-to-cell communication. Their roles in stemness maintenance have been well described. A common pathway involved in these processes is vesicular trafficking, and subsequently, regulation by Rab GTPases. In this review, we analyze the role played by Rab GTPases in stemness status, either directly or through their regulation of autophagy and EVs secretion

Nanoscale Lithium Quantification in LiXNiyCowMnZO2 as Cathode for Rechargeable Batteries

Abstract Time-of-flight secondary ion mass spectrometry (TOF-SIMS) using a focused ion-beam scanning electron microscope (FIB-SEM) is a promising and economical technique for lithium detection and quantification in battery materials because it overcomes the limitations with detecting low Li content by energy dispersive spectroscopy (EDS). In this work, an experimental calibration curve was produced, which to our best knowledge allowed for the first time, the quantification of lithium in standard nickel manganese cobalt oxide (NMC-532) cathodes using 20 nm resolution. The technique overcomes matrix effects and edges effects that makes quantification complex. This work shows the high potential of TOF-SIMS tool for analytical characterization of battery materials, and demonstrates its tremendous capabilities towards identification of various chemical or electrochemical phenomena in the cathodes via high-resolution ion distributions. Various phenomena in the ion distributions are also assessed, such as edge effects or measurement artifacts from real signal variations