Glioma cell dispersion is driven by [alfa]5 integrin-mediated cell-matrix and cell-cell interactions

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Environmentally Sensitive Fluorescent Sensors Based on Synthetic Peptides

Biosensors allow the direct detection of molecular analytes, by associating a biological receptor with a transducer able to convert the analyte-receptor recognition event into a measurable signal. We review recent work aimed at developing synthetic fluorescent molecular sensors for a variety of analytes, based on peptidic receptors labeled with environmentally sensitive fluorophores. Fluorescent indicators based on synthetic peptides are highly interesting alternatives to protein-based sensors, since they can be synthesized chemically, are stable, and can be easily modified in a site-specific manner for fluorophore coupling and for immobilization on solid supports

Oncotarget

Distant metastases arise in 20-30% of patients with squamous cell carcinoma of the head and neck (HNSCC) in the 2 years following treatment. Therapeutic options are limited and the outcome of the patients is poor. The identification of predictive biomarkers of patient at risk for distant metastasis and therapies are urgently needed. We previously identified a clinical subgroup, called "R1" characterized by high propensity for rapid distant metastasis. Here, we showed that "R1" patients do not or at very low level express caveolin-1 (Cav1). Low or no expression of Cav1 is of bad prognosis. Disappearance of Cav1 enables cells to undergo epithelial-mesenchymal transition (EMT). EMT is associated with enhanced migration and invasion. Our study uncovered a new target, α5β1 integrin. Targeting α5β1 integrins might not only prevent metastasis of HNSCC but also delay the development of the primary tumor by reducing tumor cell viability. Cav1 detection might be taken into consideration in the future in the clinic not only to identify patients at high risk of metastasis but also to select patient who might benefit from an anti-integrin therapy

Aptamères ciblant des cellules de glioblastome exprimant l'intégrine α5β1

Sciences de la vie et de la sant

Synergistic activity of the ninth and tenth FIII domains of human fibronectin depends upon structural stability.

The ninth and tenth FIII domains (FIII9-10) of human fibronectin act in synergy to promote cell adhesion via the interaction with integrin receptors. Here we describe the functional and structural properties of a set of recombinant FIII9-10 mutants containing various alanine substitutions within the key synergistic site, DRVPHSRN in FIII9, either alone or in combination with another substitution (Leu(1408) to Pro), on the opposite face of FIII9, that increases stability and the functional capacity of FIII9-10. We show that the introduction of mutations into the synergistic sequence of FIII9-10 has a negative effect on the adhesion of baby hamster kidney fibroblasts and results in reduced ability of these ligands to recognize integrin alpha(5)beta(1). Conformational stability of the FIII9 domain in the synergy site mutants is likewise reduced in comparison with native FIII9. The Leu(1408) to Pro substitution in mutant FIII9-10 proteins carrying substitutions in the synergy site results in a substantial recovery of the adhesive activity of the mutants and affinity to alpha(5)beta(1). In keeping with the enhancement of functional activity, the Leu(1408) to Pro substitution in the FIII9-10 synergy site mutants also causes a significant increase in conformational stability of FIII9. These observations imply a strong positive correlation between the biological activity and conformational stability of the assessed FIII9-10 mutants and suggest that a Leu(1408) to Pro substitution restores the biological activity of the mutants via their ability to restore their conformational stability. We conclude that domain stability may be a major determinant of the synergistic potential of FIII9. Our data underscore the value of using more than one approach in such structure-function studies and the requirement for validating the global structural integrity of protein ligands in which sequences that disrupt function have been perturbed

Selection of Nucleic Acid Aptamers Targeting Tumor Cell-Surface Protein Biomarkers

Aptamers are nucleic acids referred to as chemical antibodies as they bind to their specific targets with high affinity and selectivity. They are selected via an iterative process known as ‘selective evolution of ligands by exponential enrichment’ (SELEX). Aptamers have been developed against numerous cancer targets and among them, many tumor cell-membrane protein biomarkers. The identification of aptamers targeting cell-surface proteins has mainly been performed by two different strategies: protein- and cell-based SELEX, when the targets used for selection were proteins and cells, respectively. This review aims to update the literature on aptamers targeting tumor cell surface protein biomarkers, highlighting potentials, pitfalls of protein- and cell-based selection processes and applications of such selected molecules. Aptamers as promising agents for diagnosis and therapeutic approaches in oncology are documented, as well as aptamers in clinical development

Role of Integrins in Resistance to Therapies Targeting Growth Factor Receptors in Cancer

International audienc

SPR identification of mild elution conditions for affinity purification of E6 oncoprotein, using a multivariate experimental design.

The purification of "difficult" proteins for structural and functional studies remains a challenge. A widely used approach is their production as fusions with an affinity tag, so that a generic tag-based purification protocol can be applied. Alternatively, immuno-affinity using a protein-specific antibody allows purification of unmodified proteins in a single step, if mild elution conditions can be identified for dissociating the complex without disrupting the folding of the protein. Here, we describe a quantitative structure activity relationship (QSAR) strategy to predict optimized elution conditions from a mathematical model that relates target/antibody dissociation to environmental changes. We illustrate the strategy with the E6 protein of the human papilloma virus (HPV) 16, a highly unstable protein central to HPV-induced carcinogenesis. Surface plasmon resonance (SPR) was used to measure the kinetics of dissociation of an E6 peptide from an E6-specific antibody in a set of multivariate conditions, where three environmental factors (pH, NaCl concentration, and temperature) were varied. The QSAR model indicated that dissociation is favored at pH or = 10 if the temperature is high. We verified that the conclusions of the QSAR study with the peptide were valid for the scFv1F4/E6 protein complex, and that the recovered protein was capable of mediating p53 degradation. Finally, we demonstrated that the optimized elution conditions (pH 10, 35 degrees C) were adequate for purifying the recombinant E6 protein from crude cell extracts

Antibody Binding Selectivity: Alternative Sets of Antigen Residues Entail High-Affinity Recognition

International audienc