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Accueil > Publications > Recherche par années > Années 2010 > 2017

2017

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A 3D model of tumour angiogenic microenvironment to monitor hypoxia effects on cell interactions and cancer stem cell selection

Tumour microenvironment determines the fate of treatments. Reconstitution of tumour conditions is mandatory for alternative in vitro methods devoted to cancer development and the selection of therapeutic strategies. This work describes a 3D model of melanoma growth in its environment. Introducing means to mimic tumour angiogenesis, which turns on tumour progression, the model shows that melanoma tumour spheroids allow reconstitution of solid tumours with stromal cells. Angiogenesis evidenced the differential recruitment of endothelial cells (EC) from early progenitors (EEPCs) to mature ECs. Hypoxia was the key parameter that selected and stabilized melanoma cancer stem like cells (CSCs) phenotype based on aldehyde dehydrogenase expression as the best criterion. The 3D-tumour-model demonstrated the distinct reactivity of ECs toward tumour cells in terms of cellular cross-talk and humoral response. Intra-spheroid cell-to-cell membrane dye exchanges, mediated by intercellular interactions, uncovered the melanoma-to-EEPC cooperation. The resulting changes in tumour milieu were evidenced by the chemokinic composition and hypoxia-related variations in microRNA expression assessed in each cellular component of the spheroids. This method brings new tools to decipher the molecular mechanism of tumour-mediated cell recruitment and for in vitro assessment of therapeutic approaches.

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Efficient synthesis of cysteine-rich cyclic peptides through intramolecular native chemical ligation of N-Hnb-Cys peptide crypto-thioesters

We herein introduce a straightforward synthetic route to cysteine-containing cyclic peptides based on the intramolecular native chemical ligation of in situ generated thioesters. Key precursors are N-Hnb-Cys crypto-thioesters, easily synthesized by Fmoc-based SPPS. The strategy is applied to a representative range of naturally occurring cyclic disulfide-rich peptide sequences.

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Expression and activity of multidrug resistance proteins in mature endothelial cells and their precursors : A challenging correlation

Active cellular transporters of harmful agents-multidrug resistance (mdr) proteins-are present in tumor, stem and endothelial cells, among others. While mdr proteins are broadly studied in tumor cells, their role in non-tumor cells and the significance of their action not connected with removal of harmful xenobiotics is less extensively documented. Proper assessment of mdr proteins expression is difficult. Mdr mRNA presence is most often evaluated but that does not necessarily correlate with the protein level. The protein expression itself is difficult to determine ; usually cells with mdr overexpression are studied, not cells under physiological conditions, in which a low expression level of mdr protein is often insufficient for detection in vitro. Various methods are used to identify mdr mRNA and protein expression, together with functional tests demonstrating their biological drug transporting activities. Data comparing different methods of investigating expression of mdr mRNAs and their corresponding proteins are still scarce. In this article we present the results of a study concerning mdr mRNA and protein expression. Our goal was to search for the best method to investigate the expression level and functional activity of five selected mdr proteins-MDR1, BCRP, MRP1, MRP4 and MRP5-in established in vitro cell lines of human endothelial cells (ECs) and their progenitors. Endothelial cells demonstrated mdr presence at the mRNA level, which was not always confirmed at the protein level or in functional tests. Therefore, several different assays had to be applied for evaluation of mdr proteins expression and functions in endothelial cells. Among them functional tests seemed to be the most conclusive, although not very specific.

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Highly selective capture of minicircle DNA biopharmaceuticals by a novel zinc-histidine peptide conjugate

The use of minicircle DNA (mcDNA) biomolecules as a pharmaceutical product holds remarkable potential due to their improved therapeutic efficacy in comparison with standard non-viral gene expression vectors. However, mcDNA translation into clinical application is still highly restricted due to the lack of robust technologies for minicircles detection and purification. In this study, the potential of a zinc-binding histidine-based peptide to function as a novel ligand for mcDNA recovery was investigated by using high-throughput surface plasmon resonance (SPR) analysis. The histidine-based peptide successfully bound zinc cationic ions and had affinity towards mcDNA biomolecules as confirmed by the dynamic binding responses obtained in SPR experiments. Notably, the obtained results indicate that not only zinc-peptide ligands are able to bind mcDNA with very high affinity (K-D = 4.21 x 10(-10) M), but also that this interaction is mostly dependent on buffer type. In general, the findings indicated that Zn2+ bound peptide has high affinity to mcDNA in low ionic strength buffers, whereas with high salt buffers no binding is detected. Overall, the novel zinc-binding peptide has shown to have suitable properties for mcDNA binding and recovery under experimental conditions that assure genetic material stability. More importantly, the straightforward approach of employing simple biomimetic ligands for mcDNA capture will contribute for development of new technologies to purify DNA biopharmaceuticals.

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Microalgae amino acid extraction and analysis at nanomolar level using electroporation and capillary electrophoresis with laser-induced fluorescence detection

Amino acids play a key role in food analysis, clinical diagnostics, and biochemical research. Capillary electrophoresis with laser-induced fluorescence detection was used for the analysis of several amino acids. Amino acid labeling with fluorescein isothiocyanate was conducted using microwave-assisted derivatization at 80 degrees C (680 W) during only 150 s. Good electrophoretic resolution was obtained using a background electrolyte composed of sodium tetraborate buffer (100 mM ; pH 9.4) and -cyclodextrin (10 mM), and the limits of quantification were 3-30 nM. The developed capillary electrophoresis with laser-induced fluorescence method was used to analyze amino acids in Dunaliella salina green algae grown under different conditions. A simple extraction technique based on electroporation of the cell membrane was introduced. A home-made apparatus allowed the application of direct and alternating voltages across the electrochemical compartment containing a suspension of microalgae in distilled water at 2.5 g/L. A direct voltage of 12 V applied for 4 min gave the optimum extraction yield. Results were comparable to those obtained with accelerated-solvent extraction. The efficiency of electroporation in destroying microalgae membranes was shown by examining the algae surface morphology using scanning electron microscopy. Stress conditions were found to induce the production of amino acids in Dunaliella salina cells.

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MicroRNAs in Neurocognitive Dysfunctions : New Molecular Targets for Pharmacological Treatments ?

BACKGROUND : Neurodegenerative and cognitive disorders are multifactorial diseases (i.e., involving neurodevelopmental, genetic, age or environmental factors) characterized by an abnormal development that affects neuronal function and integrity. Recently, an increasing number of studies revealed that the dysregulation of microRNAs (miRNAs) may be involved in the etiology of cognitive disorders as Alzheimer, Parkinson, and Huntington’s diseases, Schizophrenia and Autism spectrum disorders.
METHODS : From an extensive search in bibliographic databases of peer-reviewed research literature, we identified relevant published studies related to specific key words such as memory, cognition, neurodegenerative disorders, neurogenesis and miRNA. We then analysed, evaluated and summerized scientific evidences derived from these studies.
RESULTS : We first briefly summarize the basic molecular events involved in memory, a process inherent to cognitive disease, and then describe the role of miRNAs in neurodevelopment, synaptic plasticity and memory. Secondly, we provide an overview of the impact of miRNA dysregulation in the pathogenesis of different neurocognitive disorders, and lastly discuss the feasibility of miRNA-based therapeutics in the treatment of these disorders.
CONCLUSION : This review highlights the molecular basis of neurodegenerative and cognitive disorders by focusing on the impact of miRNAs dysregulation in these pathological phenotypes. Altogether, the published reports suggest that miRNAs-based therapy could be a viable therapeutic alternative to current treatment options in the future.

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Petrographical and Mineralogical Applications of Raman Mapping

Raman spectroscopy has undergone rapid development over the last few decades. The ability to acquire a spectrum in only a few tens of milliseconds allows use of Raman mapping as a routine technique. However, with respect to classical single spectrum measurement, this technique is not still as widely used as it could be, in particular for mineralogy and petrography. Here, we explain the advantages of Raman mapping for obtaining additional information compared to single spot analyses. The principle and the limits of the technique are first explained in 2D and 3D. Data processing techniques are then described using different types of rocks and minerals to demonstrate the utility of Raman mapping for obtaining information about the general composition, identification of small phases, as well as for distinguishing minerals that are spectrally very close. More “exotic” uses of the collected signal are also described. Finally, a gallery of images from representative samples is used to illustrate the discussion.

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Pharmacomodulation of microRNA expression in neurocognitive diseases : obstacles and future opportunities

Given the importance of microRNAs (miRNAs) in modulating brain functions and their implications in neurocognitive disorders there are currently significant efforts devoted in the field of miRNA-based therapeutics to correct and/or to treat these brain diseases. The observation that miRNA 29a/b-1 cluster, miRNA 10b and miRNA 7, for instance, are frequently deregulated in the brains of patients with neurocognitive diseases and in animal models of Alzheimer, Huntington’s and Parkinson’s diseases, suggest that correction of miRNA expression using agonist or antagonist miRNA oligonucleotides might be a promising approach to correct or even to cure such diseases. The encouraging results from recent clinical trials allow envisioning that pharmacological approaches based on miRNAs might, in a near future, reach the requirements for successful therapeutic outcomes and will improve the healthcare of patients with brain injuries or disorders. This review will focus on the current strategies used to modulate pharmacological function of miRNA using chemically modified oligonucleotides. We will then review the recent literature on strategies to improve nucleic acid delivery across the blood-brain barrier which remains a severe obstacle to the widespread application of miRNA therapeutics to treat brain diseases. Finally, we provide a state-of-art of current preclinical research performed in animal models for the treatment of neurocognitive disorders using miRNA as therapeutic agents and discuss future developments of miRNA therapeutics.

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Scientific workflows for computational reproducibility in the life sciences : Status, challenges and opportunities

With the development of new experimental technologies, biologists are faced with an avalanche of data to be computationally analyzed for scientific advancements and discoveries to emerge. Faced with the complexity of analysis pipelines, the large number of computational tools, and the enormous amount of data to manage, there is compelling evidence that many if not most scientific discoveries will not stand the test of time : increasing the reproducibility of computed results is of paramount importance.

The objective we set out in this paper is to place scientific workflows in the context of reproducibility. To do so, we define several kinds of reproducibility that can be reached when scientific workflows are used to perform experiments. We characterize and define the criteria that need to be catered for by reproducibility-friendly scientific workflow systems, and use such criteria to place several representative and widely used workflow systems and companion tools within such a framework. We also discuss the remaining challenges posed by reproducible scientific workflows in the life sciences. Our study was guided by three use cases from the life science domain involving in silico experiments.

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