New anticancer agents mimicking protein recognition motifs

Mn(OAc)2-promoted [3+2] cyclization of enaminone with isocyanoacetate: Rapid access to pyrrole-2-carboxylic ester derivatives with potent anticancer activity

The practical and facile Mn(OAc)2-promoted [3+2] cycloaddition reaction of enaminones with isocyanoacetate was developed, that delivered a diversity of 3-aroyl pyrrole-2-carboxylic esters with broad substrates scope. The most of the newly synthesized compounds exhibit moderate antiproliferative activity against four cancer cells. Notably, compound 2n demonstrate the most potent activity with average IC50 values of 5.61 μM against four distinct cancer cell lines. Moreover, 2n exhibit favorable anti-migration activity and drug-like properties. The further investigation suggests that compound 2n possesses the ability to inhibit ERK5 activity and exhibits effective binding with the ERK5 protein, making it a promising candidate as a lead compound for a new class of ERK5 inhibitors discovery.

Tetrasubstituted Pyrrole Derivative Mimetics of Protein-Protein Interaction Hot-Spot Residues: A Promising Class of Anticancer Agents Targeting Melanoma Cells

A new series of tetrasubstituted pyrrole derivatives (TSPs) was synthesized based on a previously developed hypothesis on their ability to mimic hydrophobic protein motifs. The resulting new TSPs were endowed with a significant toxicity against human epithelial melanoma A375 cells, showing IC₅₀ values ranging from 10 to 27 μM, consistent with the IC₅₀ value of the reference compound nutlin-3a (IC₅₀ = 15 μM). In particular, compound 10a (IC₅₀ = 10 μM) resulted as both the most soluble and active among the previous and present TSPs. The biological investigation evidenced that the anticancer activity is related to the activation of apoptotic cell-death pathways, supporting our rational design based on the ability of TSPs to interfere with PPI involved in the cell cycle regulation of cancer cells and, in particular, the p53 pathway. A reinvestigation of the TSP pharmacophore by using DFT calculations showed that the three aromatic substituents on the pyrrole core are able to mimic the hydrophobic side chains of the hot-spot residues of parallel and antiparallel coiled coil structures suggesting a possible molecular mechanism of action. A structure-activity relationship (SAR) analysis which includes solubility studies allows us to rationalize the role of the different substituents on the pyrrole core.

Evaluation of Muscle Proteins for Estimating the Post-Mortem Interval in Veterinary Forensic Pathology

Postmortem cadaveric changes are commonly used to estimate the postmortem interval (PMI) in humans and animals. However, these modifications have been poorly investigated in animals of interest to veterinary forensic pathology. The aim of this study was to investigate the potential use of muscle proteins (desmin and dystrophin) as biomarkers for estimating the PMI in dogs. For this study, 10 dead adult dogs were evaluated for 4 days in a temperature-controlled room at 19 ± 1 °C. For each animal, at 3, 24, 48, 72, and 96 h after death, a 1 × 1 × 1 cm cube of muscle tissue was removed from the vastus lateralis and triceps brachii. Protein expression levels were analyzed by immunohistochemical examination and immunoblot analysis. The obtained results showed rapid dystrophin degradation, with complete disappearance at 72 h after death. In contrast, desmin-positive fibers and desmin protein bands detected by immunoblot were observed on all 4 days of observation. Our findings suggest the potential use of muscle proteins as biomarkers for estimating the PMI in dogs.

N-Substituted l-Iminosugars for the Treatment of Sanfilippo Type B Syndrome

Sanfilippo syndrome comprises a group of four genetic diseases due to the lack or decreased activity of enzymes involved in heparan sulfate (HS) catabolism. HS accumulation in lysosomes and other cellular compartments results in tissue and organ dysfunctions, leading to a wide range of clinical symptoms including severe neurodegeneration. To date, no approved treatments for Sanfilippo disease exist. Here, we report the ability of N-substituted l-iminosugars to significantly reduce substrate storage and lysosomal dysfunctions in Sanfilippo fibroblasts and in a neuronal cellular model of Sanfilippo B subtype. Particularly, we found that they increase the levels of defective α-N-acetylglucosaminidase and correct its proper sorting toward the lysosomal compartment. Furthermore, l-iminosugars reduce HS accumulation by downregulating protein levels of exostosin glycosyltransferases. These results highlight an interesting pharmacological potential of these glycomimetics in Sanfilippo syndrome, paving the way for the development of novel therapeutic approaches for the treatment of such incurable disease.

Eudraguard® Natural and Protect: New "Food Grade" Matrices for the Delivery of an Extract from Sorbus domestica L. Leaves Active on the α-Glucosidase Enzyme

(1) Background: Eudraguard^® Natural (EN) and Protect (EP) are polymers regulated for use in dietary supplements in the European Union and the United States to carry natural products, mask unpleasant smells and tastes, ameliorate product handling, and protect products from moisture, light, and oxidation. Moreover, EN and EP can control the release of encapsulated compounds. The aim of this work was the development, preparation, and control of Eudraguard^® spray-drying microparticles to obtain powders with easy handling and a stable dietary supplement containing a polar functional extract (SOE) from Sorbus domestica L. leaves. (2) Methods: SOE was characterized using HPLC, NMR, FTIR, DSC, and SEM methods. Furthermore, the SOE's antioxidant/free radical scavenging activity, α-glucosidase inhibition, MTT assay effect on viability in normal cells, and shelf life were evaluated in both the extract and final formulations. (3) Results: The data suggested that SOE, rich in flavonoids, is a bioactive and safe extract; however, from a technological point of view, it was sticky, difficult to handle, and had low aqueous solubility. Despite the fact that EN and EP may undergo changes with spray-drying, they effectively produced easy-to-handle micro-powders with a controlled release profile. Although EN had a weaker capability to coat SOE than EP, EN acted as a substrate that was able to swell, drawing in water and improving the extract solubility and dissolution/release; however, EP was also able to carry the extract and provide SOE with controlled release. (4) Conclusion: Both Eudraguard^® products were capable of carrying SOE and improving its antioxidant and α-glucosidase inhibition activities, as well as the extract stability and handling.

Structural Refinement of 2,4-Thiazolidinedione Derivatives as New Anticancer Agents Able to Modulate the BAG3 Protein

The multidomain BAG3 protein is a member of the BAG (Bcl-2-associated athanogene) family of co-chaperones, involved in a wide range of protein-protein interactions crucial for many key cellular pathways, including autophagy, cytoskeletal dynamics, and apoptosis. Basal expression of BAG3 is elevated in several tumor cell lines, where it promotes cell survival signaling and apoptosis resistance through the interaction with many protein partners. In addition, its role as a key player of several hallmarks of cancer, such as metastasis, angiogenesis, autophagy activation, and apoptosis inhibition, has been established. Due to its involvement in malignant transformation, BAG3 has emerged as a potential and effective biological target to control multiple cancer-related signaling pathways. Recently, by using a multidisciplinary approach we reported the first synthetic BAG3 modulator interfering with its BAG domain (BD), based on a 2,4-thiazolidinedione scaffold and endowed with significant anti-proliferative activity. Here, a further in silico-driven selection of a 2,4-thiazolidinedione-based compound was performed. Thanks to a straightforward synthesis, relevant binding affinity for the BAG3BD domain, and attractive biological activities, this novel generation of compounds is of great interest for the development of further BAG3 binders, as well as for the elucidation of the biological roles of this protein in tumors. Specifically, we found compound 6 as a new BAG3 modulator with a relevant antiproliferative effect on two different cancer cell lines (IC₅₀: A375 = 19.36 μM; HeLa = 18.67 μM).

Targeted Metabolomic Analysis of a Mucopolysaccharidosis IIIB Mouse Model Reveals an Imbalance of Branched-Chain Amino Acid and Fatty Acid Metabolism

Mucopolysaccharidoses (MPSs) are inherited disorders of the glycosaminoglycan (GAG) metabolism. The defective digestion of GAGs within the intralysosomal compartment of affected patients leads to a broad spectrum of clinical manifestations ranging from cardiovascular disease to neurological impairment. The molecular mechanisms underlying the progression of the disease downstream of the genetic mutation of genes encoding for lysosomal enzymes still remain unclear. Here, we applied a targeted metabolomic approach to a mouse model of PS IIIB, using a platform dedicated to the diagnosis of inherited metabolic disorders, in order to identify amino acid and fatty acid metabolic pathway alterations or the manifestations of other metabolic phenotypes. Our analysis highlighted an increase in the levels of branched-chain amino acids (BCAAs: Val, Ile, and Leu), aromatic amino acids (Tyr and Phe), free carnitine, and acylcarnitines in the liver and heart tissues of MPS IIIB mice as compared to the wild type (WT). Moreover, Ala, Met, Glu, Gly, Arg, Orn, and Cit amino acids were also found upregulated in the liver of MPS IIIB mice. These findings show a specific impairment of the BCAA and fatty acid catabolism in the heart of MPS IIIB mice. In the liver of affected mice, the glucose-alanine cycle and urea cycle resulted in being altered alongside a deregulation of the BCAA metabolism. Thus, our data demonstrate that an accumulation of BCAAs occurs secondary to lysosomal GAG storage, in both the liver and the heart of MPS IIIB mice. Since BCAAs regulate the biogenesis of lysosomes and autophagy mechanisms through mTOR signaling, impacting on lipid metabolism, this condition might contribute to the progression of the MPS IIIB disease.

Tetra-substituted pyrrole derivatives act as potent activators of p53 in melanoma cells

Cutaneous melanoma, the most aggressive form of skin cancer, is characterized by activating BRAF mutations. Despite the initial success of selective BRAF inhibitors, only few patients exhibited complete responses, whereas many showed disease progression. Melanoma is one of the few types of cancer in which p53 is not frequently mutated, but p53 inactivation can be indirectly achieved by a stable activation of MDM2 induced by a deletion in CDKN2A (Cyclin Dependent Kinase Inhibitor 2A) locus, encoding for p16INK4A and p14ARF, two tumor suppressor genes. In this study, we tested the efficacy of the previously synthesized tetra-substituted pyrrole derivatives, 8 g, 8 h and 8i, in melanoma cell lines, and we compared the effects of the most active of these, the 8i compound, with that exerted by Nutlin 3, a well-known inhibitor of p53-MDM2 interaction. The obtained results showed that 8i potentiates the inhibitory effect of Nutlin 3 and the combined use of 8i and Nutlin 3 triggers apoptosis and significantly impairs melanoma viability. Finally, the 8i compound reduces p53-MDM2 interaction and induces p53-HSP90 complex formation, suggesting that the observed raise in p53 transcriptional activity could be mediated by HSP90. Because the main feature of melanoma is the resistance to most chemotherapeutics, our studies suggest that the 8i tetra-substituted pyrrole derivative, restoring p53 functions and its transcriptional activities, may have potential application, at least as adjuvant, in the treatment of human melanoma.

BAG3 Protein Is Involved in Endothelial Cell Response to Phenethyl Isothiocyanate

Phenethyl isothiocyanate (PEITC), a cruciferous vegetable-derived compound, is a versatile cancer chemopreventive agent that displays the ability to inhibit tumor growth during initiation, promotion, and progression phases in several animal models of carcinogenesis. In this report, we dissect the cellular events induced by noncytotoxic concentrations of PEITC in human umbilical vein endothelial cells (HUVECs). In the early phase, PEITC treatment elicited cells' morphological changes that comprise reduction in cell volume and modification of actin organization concomitantly with a rapid activation of the PI3K/Akt pathway. Downstream to PI3K, PEITC also induces the activity of Rac1 and activation of c-Jun N-terminal kinase (JNK), well-known regulators of actin cytoskeleton dynamics. Interestingly, PEITC modifications of the actin cytoskeleton were abrogated by pretreatment with JNK inhibitor, SP600125. JNK signaling led also to the activation of the c-Jun transcription factor, which is involved in the upregulation of several genes; among them is the BAG3 protein. This protein, a member of the BAG family of heat shock protein (Hsp) 70 cochaperones, is able to sustain survival in different tumor cell lines and neoangiogenesis by directly regulating the endothelial cell cycle. Furthermore, BAG3 is involved in maintaining actin folding. Our findings indicate that BAG3 protein expression is induced in endothelial cells upon exposure to a noncytotoxic concentration of PEITC and its expression is requested for the recovery of normal cell size and morphology after the stressful stimuli. This assigns an additional role for BAG3 protein in the endothelial cells after a stress event.

Investigating the Neuroprotective Effects of Turmeric Extract: Structural Interactions of β-Amyloid Peptide with Single Curcuminoids

A broad biophysical analysis was performed to investigate the molecular basis of the neuroprotective action of Curcuma longa extracts in Alzheimer's disease. By combining circular dichroism and electron paramagnetic resonance experiments with molecular modeling calculations, the minor components of Curcuma longa extracts, such as demethoxycurcumin (2, DMC), bisdemethoxycurcumin (3, BDMC) and cyclocurcumin (4, CYC), were analyzed in a membrane environment mimicking the phospholipid bilayer. Our study provides the first evidence on the relative role of single curcuminoids interacting with Aβ-peptide. When the CYC and curcumin metabolite tetrahydrocurcumin (5, THC) were inserted into an anionic lipid solution, a significant modification of the Aβ CD curves was detected. These data were implemented by EPR experiments, demonstrating that CYC reaches the inner part of the bilayer, while the other curcuminoids are localized close to the membrane interface. Computational studies provided a model for the curcuminoid-Aβ interaction, highlighting the importance of a constrained "semi-folded" conformation to interact with Aβ analogously to the pattern observed in α-helical coiled-coil peptide structures. This combined approach led to a better understanding of the intriguing in vitro and in vivo activity of curcuminoids as anti-Alzheimer agents, paving a new path for the rational design of optimized druggable analogues.

Discovery of Novel Isatin-Based p53 Inducers

A series of isatin Schiff base derivatives were identified during in silico screening of the small molecule library for novel activators of p53. The compounds selected based on molecular docking results were further validated by a high-content screening assay using U2OS human osteosarcoma cells with an integrated EGFP-expressing p53-dependent reporter. The hit compounds activated and stabilized p53, as shown by Western blotting, at higher rates than the well-known positive control Nutlin-3. Thus, the p53-activating compounds identified by this approach represent useful molecular probes for various cancer studies.

Apoptosis therapy in cancer: the first single-molecule co-activating p53 and the translocator protein in glioblastoma

In the complex scenario of cancer, treatment with compounds targeting multiple cell pathways has been emerging. In Glioblastoma Multiforme (GBM), p53 and Translocator Protein (TSPO), both acting as apoptosis inducers, represent two attractive intracellular targets. On this basis, novel indolylglyoxylyldipeptides, rationally designed to activate TSPO and p53, were synthesized and biologically characterized. The new compounds were able to bind TSPO and to reactivate p53 functionality, through the dissociation from its physiological inhibitor, murine double minute 2 (MDM2). In GBM cells, the new molecules caused Δψm dissipation and inhibition of cell viability. These effects resulted significantly higher with respect to those elicited by the single target reference standards applied alone, and coherent with the synergism resulting from the simultaneous activation of TSPO and p53. Taken together, these results suggest that TSPO/MDM2 dual-target ligands could represent a new attractive multi-modal opportunity for anti-cancer strategy in GBM.