Peptoids: Smart and Emerging Candidates for the Diagnosis of Cancer, Neurological and Autoimmune Disorders.

Early detection of fatal and disabling diseases such as cancer, neurological and autoimmune dysfunctions is still desirable yet challenging to improve quality of life and longevity. Peptoids (N-substituted glycine oligomers) are a relatively new class of peptidomimetics, being highly versatile and capable of mimicking the architectures and the activities of the peptides but with a marked resistance to proteases and a propensity to cross the cellular membranes over the peptides themselves. For these properties, they have gained an ever greater interest in applications in bioengineering and biomedical fields.

High-Resolution Conformational Analysis of RGDechi-Derived Peptides Based on a Combination of NMR Spectroscopy and MD Simulations.

The crucial role of integrin in pathological processes such as tumor progression and metastasis formation has inspired intense efforts to design novel pharmaceutical agents modulating integrin functions in order to provide new tools for potential therapies. In the past decade, we have investigated the biological proprieties of the chimeric peptide RGDechi, containing a cyclic RGD motif linked to an echistatin C-terminal fragment, able to specifically recognize αvβ3 without cross reacting with αvβ5 and αIIbβ3 integrin. Additionally, we have demonstrated using two RGDechi-derived peptides, called RGDechi1-14 and ψRGDechi, that chemical modifications introduced in the C-terminal part of the peptide alter or abolish the binding to the αvβ3 integrin.

Screening a Molecular Fragment Library to Modulate the PED/PEA15-Phospholipase D1 Interaction in Cellular Lysate Environments.

The overexpression of PED/PEA15, the phosphoprotein enriched in diabetes/phosphoprotein enriched in the astrocytes 15 protein (here referred simply to as PED), observed in some forms of type II diabetes, reduces the transport of insulin-stimulated glucose by binding to the phospholipase D1 (PLD1). The inhibition of the PED/PLD1 interaction was shown to restore basal glucose transport, indicating PED as a pharmacological target for the development of drugs capable of improving insulin sensitivity and glucose tolerance. We here report the identification and selection of PED ligands by means of NMR screening of a library of small organic molecules, NMR characterization of the PED/PLD1 interaction in lysates of cells expressing PLD1, and modulation of such interactions using BPH03, the best selected ligand.

An Overview of Peptide-Based Molecules as Potential Drug Candidates for Multiple Sclerosis.

Multiple sclerosis (MS) belongs to demyelinating diseases, which are progressive and highly debilitating pathologies that imply a high burden both on individual patients and on society. Currently, several treatment strategies differ in the route of administration, adverse events, and possible risks. Side effects associated with multiple sclerosis medications range from mild symptoms, such as flu-like or irritation at the injection site, to serious ones, such as progressive multifocal leukoencephalopathy and other life-threatening events.

A novel approach for studying receptor-ligand interactions on living cells surface by using NUS/T1ρ-NMR methodologies combined with computational techniques: The RGDechi15D-αβ integrin complex.

Structural investigations of receptor-ligand interactions on living cells surface by high-resolution Nuclear Magnetic Resonance (NMR) are problematic due to their short lifetime, which often prevents the acquisition of experiments longer than few hours. To overcome these limitations, we developed an on-cell NMR-based approach for exploring the molecular determinants driving the receptor-ligand recognition mechanism under native conditions. Our method relies on the combination of high-resolution structural and dynamics NMR data with Molecular Dynamics simulations and Molecular Docking studies.

Selective Targeting of αvβ5 Integrin in HepG2 Cell Line by RGDechi15D Peptide.

Recently, the research community has become increasingly concerned with the receptor αvβ5, a member of the well-known integrin family. Different ongoing studies have evidenced that αvβ5 integrin regulates not only physiological processes but also a wide array of pathological events, suggesting the receptor as a valuable biomarker to specifically target for therapeutic/diagnostic purposes. Remarkably, in some tumors the involvement of the receptor in cell proliferation, tumor dissemination and angiogenesis is well-documented.

A Multi-Targeting Approach to Fight SARS-CoV-2 Attachment.

The public health has declared an international state of emergency due to the spread of a new coronavirus (SARS-CoV-2) representing a real pandemic threat so that to find potential therapeutic agents is a dire need. To this aim, the SARS-CoV-2 spike (S) glycoprotein represents a crucial target for vaccines, therapeutic antibodies, and diagnostics. Since virus binding to ACE-2 alone could not be sufficient to justify such severe infection, in order to facilitate medical countermeasure development and to search for new targets, two further regions of S protein have been taken into consideration here.

Gold-Speckled SPION@SiO Nanoparticles Decorated with Thiocarbohydrates for ASGPR1 Targeting: Towards HCC Dual Mode Imaging Potential Applications.

Efforts are made to perform an early and accurate detection of hepatocellular carcinoma (HCC) by simultaneous exploiting multiple clinically non-invasive imaging modalities. Original nanostructures derived from the combination of different inorganic domains can be used as efficient contrast agents in multimodal imaging. Superparamagnetic iron oxide nanoparticles (SPIONs) and Au nanoparticles (NPs) possess well-established contrasting features in magnetic resonance imaging (MRI) and X-ray computed tomography (CT), respectively.

On-Bead Peptoid Dimerization Induced by Incorporation of Glycosylated Bridging Units in Submonomer Solid-Phase Approach to Glycopeptoids.

A study on submonomer solid-phase synthesis of S-glycopeptoids has been carried out by screening different parameters. Dimeric species, featuring glycosylated bridging amino monomers, were found under suitable conditions. These dimers arise from an on-resin cross-linking reaction occurring with the incorporation of a glycoamino submonomer into the growing chain and subsequent nucleophilic attack of the resulting secondary amine to a still unreacted bromoacetylated unit.

Conformational studies of RGDechi peptide by natural-abundance NMR spectroscopy.

Integrins are heterodimeric cell-surface proteins that play important roles during developmental and pathological processes. Diverse human pathologies involve integrin adhesion including thrombotic diseases, inflammation, tumour progression, fibrosis, and infectious diseases. Although in the past decade, novel integrin-inhibitor drugs have been developed for integrin-based medical applications, the structural determinants modulating integrin-ligands recognition mechanisms are still poorly understood, reducing the number of integrin subtype exclusive antagonists.

Therapeutic Potential of a Novel αβ₃ Antagonist to Hamper the Aggressiveness of Mesenchymal Triple Negative Breast Cancer Sub-Type.

The mesenchymal sub-type of triple negative breast cancer (MES-TNBC) has a highly aggressive behavior and worse prognosis, due to its invasive and stem-like features, that correlate with metastatic dissemination and resistance to therapies. Furthermore, MES-TNBC is characterized by the expression of molecular markers related to the epithelial-to-mesenchymal transition (EMT) program and cancer stem cells (CSCs). The altered expression of αβ₃ integrin has been well established as a driver of cancer progression, stemness, and metastasis.

[Tc][Tc(N)PNP43]-Labeled RGD Peptides As New Probes for a Selective Detection of αvβ Integrin: Synthesis, Structure-Activity and Pharmacokinetic Studies.

New integrin-selective molecules suitable for therapeutic or imaging purposes are currently of interest in development of effective personalized medical platforms. RGDechi is a bifunctional peptide selective for integrin αβ. Herein, RGDechi and three truncated derivatives functionalized with a cysteine (1-4) were synthesized and labeled with the [Tc][Tc(N)PNP43]-synthon ([PNP43 = (CH)P(CH)N(CHOCH)(CH)P(CH)]) (Tc1-4) as a basis for selective integrin recognition.

Chemical Modification for Proteolytic Stabilization of the Selective αβ Integrin RGDechi Peptide: in Vitro and in Vivo Activities on Malignant Melanoma Cells.

Herein, we report the synthesis and biological characterization of the new peptide ψRGDechi as the first step toward novel-targeted theranostics in melanoma. This pseudopeptide is designed from our previously reported RGDechi peptide, known to bind selectively αβ integrin, and differs for a modified amide bond at the main protease cleavage site. This chemical modification drastically reduces the enzymatic degradation in serum, compared to its parental peptide, resulting in an overall magnification of the biological activity on a highly expressing αβ human metastatic melanoma cell line.

Insights into the anticancer properties of the first antimicrobial peptide from Archaea.

Background: The peptide VLL-28, identified in the sequence of an archaeal protein, the transcription factor Stf76 from Sulfolobus islandicus, was previously identified and characterized as an antimicrobial peptide, possessing a broad-spectrum antibacterial activity.

Methods: Through a combined approach of NMR and Circular Dichroism spectroscopy, Dynamic Light Scattering, confocal microscopy and cell viability assays, the interaction of VLL-28 with the membranes of both parental and malignant cell lines has been characterized and peptide mechanism of action has been studied.

Results: It is here demonstrated that VLL-28 selectively exerts cytotoxic activity against murine and human tumor cells.

A Combined NMR and Computational Approach to Determine the RGDechi-hCit-αv β3 Integrin Recognition Mode in Isolated Cell Membranes.

The critical role of integrins in tumor progression and metastasis has stimulated intense efforts to identify pharmacological agents that can modulate integrin function. In recent years, αv β3 and αv β5 integrin antagonists were demonstrated to be effective in blocking tumor progression. RGDechi-hCit, a chimeric peptide containing a cyclic RGD motif linked to an echistatin C-terminal fragment, is able to recognize selectively αv β3 integrin both in vitro and in vivo.

Straightforward entry to S-glycosylated fmoc-amino acids and their application to solid phase synthesis of glycopeptides and glycopeptidomimetics.

Streamlined access to S-glycosylated Fmoc-amino acids was developed. The process provides diverse glycosylated modified amino acids in high yield and stereoselectivity taking advantage of the in situ generation of a glycosylthiolate obtained from carbohydrate acetates in a few steps. Mild basic conditions make the conjugation reaction compatible with Fmoc-iodo-amino acids.

RGDechi-hCit: αvβ3 selective pro-apoptotic peptide as potential carrier for drug delivery into melanoma metastatic cells.

αvβ3 integrin is an important tumor marker widely expressed on the surface of cancer cells. Recently, we reported some biological features of RGDechi-hCit, an αvβ3 selective peptide antagonist. In the present work, we mainly investigated the pro-apoptotic activity of the molecule and its ability to penetrate the membrane of WM266 cells, human malignant melanoma cells expressing high levels of αvβ3 integrin.

Structural Zn(II) implies a switch from fully cooperative to partly downhill folding in highly homologous proteins.

In the funneled landscape, proteins fold to their native states through a stochastic process in which the free energy decreases spontaneously and unfolded, transition, native, and possible intermediate states correspond to local minima or saddle points. Atomic description of the folding pathway appears therefore to be essential for a deep comprehension of the folding mechanism. In metallo-proteins, characterization of the folding pathways becomes even more complex, and therefore, despite their fundamental role in critical biological processes, little is known about their folding and assembly.

In vitro activity of the αvβ3 integrin antagonist RGDechi-hCit on malignant melanoma cells.

Background: In malignant melanoma (MM), overexpression of αvβ3 integrin is linked to a more metastatic phenotype. Development of anti-αvβ3 agents able to counteract melanoma progression would be helpful for disease treatment. A new selective ligand of αvβ3, RGDechi-hCit, has anti-angiogenic properties against endothelial cells in animal angiogenesis models.

Gold nanoparticles capped by a GC-containing peptide functionalized with an RGD motif for integrin targeting.

Gold nanoparticles were obtained by reduction of a tetrachloroaurate aqueous solution in the presence of a RGD-(GC)(2) peptide as stabilizer. As comparison, the behavior of the (GC)(2) peptide has been studied. The (GC)(2) and RGD-(GC)(2) peptides were prepared ad hoc by Fmoc synthesis.

Structure-based design of a potent artificial transactivation domain based on p53.

Malfunctions in transcriptional regulation are associated with a number of critical human diseases. As a result, there is considerable interest in designing artificial transcription activators (ATAs) that specifically control genes linked to human diseases. Like native transcriptional activator proteins, an ATA must minimally contain a DNA-binding domain (DBD) and a transactivation domain (TAD) and, although there are several reliable methods for designing artificial DBDs, designing artificial TADs has proven difficult.

Zinc to cadmium replacement in the A. thaliana SUPERMAN Cys₂ His₂ zinc finger induces structural rearrangements of typical DNA base determinant positions.

Among heavy metals, whose toxicity cause a steadily increasing of environmental pollution, cadmium is of special concern due to its relatively high mobility in soils and potential toxicity at low concentrations. Given their ubiquitous role, zinc fingers domains have been proposed as mediators for the toxic and carcinogenic effects exerted by xenobiotic metals. To verify the structural effects of zinc replacement by cadmium in zinc fingers, we have determined the high resolution structure of the single Cys₂ His₂ zinc finger of the Arabidopsis thaliana SUPERMAN protein (SUP37) complexed to the cadmium ion by means of UV-vis and NMR techniques.

Characterization of a designed vascular endothelial growth factor receptor antagonist helical peptide with antiangiogenic activity in vivo.

Angiogenesis is a fundamental process underlining physiological and pathological conditions. It is mainly regulated by the vascular endothelial growth factor (VEGF) and its receptors, which are the main targets of molecules able to modulate the angiogenic response. Pharmaceutical therapies based on antiangiogenic drugs represent a promising approach for the treatment of several socially important diseases.