Design, synthesis, and structure-activity relationship exploration of 1-substituted 4-aroyl-3-hydroxy-5-phenyl-1H-pyrrol-2(5H)-one analogues as inhibitors of the annexin A2-S100A10 protein interaction

S100A10 promotes cancer metastasis via recruitment of MDSCs within the lungs

Tumor-derived exosomes bind to organ resident cells, activating S100 molecules during the remodeling of the local immune microenvironment. However, little is known regarding how organ resident cell S100A10 mediates cancer metastatic progression. Here, we provided evidence that S100A10 plays an important role in regulating the lung immune microenvironment and cancer metastasis. S100A10-deficient mice reduced cancer metastasis in the lung. Furthermore, the activation of S100A10 within lung fibroblasts via tumor-derived exosomes increased the expression of CXCL1 and CXCL8 chemokines, accompanied by the myeloid-derived suppressor cells (MDSCs) recruitment. S100A10 inhibitors such as 1-Substituted-4-Aroyl-3-hydroxy-5-Phenyl-1 H-5-pyrrol-2(5 H)-ones inhibit lung metastasis in vivo. Our findings highlight the crucial role of S100A10 in driving MDSC recruitment in order to remodel the lung immune microenvironment and provide potential therapeutic targets to block cancer metastasis to the lung.

Synthetic Approaches to Novel Human Carbonic Anhydrase Isoform Inhibitors Based on Pyrrol-2-one Moiety

New dihydro-pyrrol-2-one compounds, featuring dual sulfonamide groups, were synthesized through a one-pot, three-component approach utilizing trifluoroacetic acid as a catalyst. Computational analysis using density functional theory (DFT) and condensed Fukui function explored the structure-reactivity relationship. Evaluation against human carbonic anhydrase isoforms (hCA I, II, IX, XII) revealed potent inhibition. The widely expressed cytosolic hCA I was inhibited across a range of concentrations (KI 3.9-870.9 nM). hCA II, also cytosolic, exhibited good inhibition as well. Notably, all compounds effectively inhibited tumor-associated hCA IX (KI 1.9-211.2 nM) and hCA XII (low nanomolar). Biological assessments on MCF7 cancer cells highlighted the compounds' ability, in conjunction with doxorubicin, to significantly impact tumor cell viability. These findings underscore the potential therapeutic relevance of the synthesized compounds in cancer treatment.

Novel antimicrobial iodo-dihydro-pyrrole-2-one compounds

Aim: A series of new hybrid molecules with two iodine atoms on the sides were synthesized. Methods: A one-pot, two-component method with trifluoroacetic acid as an effective catalyst to obtain dihydro-pyrrol-2-one compounds was developed. Short reaction times, a cheap catalyst, high yields and clean work-up are benefits of this method. Results: The chemical structures of the newly synthesized compounds were verified through spectroscopic techniques. Their antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans was tested in vitro. Conclusion: NC- and OH- radicals confer broad-spectrum antimicrobial activity, including against Gram-positive and Gram-negative bacteria and yeasts. Compounds 3g >7 and >9 were most active on the two bacterial species, while 3l >9 and >3i were most active against the fungal strain.

Modular approach to non-aromatic and aromatic pyrroles through gold-catalyzed [3 + 2] cycloaddition of 2H-azirines and ynamides

The developed modular approach to hard-to-reach non-aromatic 3H- and 2H-pyrroles is based on the integration of 2H-azirines and ynamides.

Gold-catalyzed oxidative cyclization of amide-alkynes: access to functionalized γ-lactams

An efficient gold-catalyzed oxidative cyclization of amide-alkynes is developed. A series of functionalized γ-lactams are easily accessed by employing this strategy. The tandem reaction proceeds through alkyne oxidation, carbene/alkyne metathesis, and donor/donor carbene oxidation.

Cu(i)- and Au(i)-catalyzed regioselective oxidation of diynes: divergent synthesis of N-heterocycles

The efficient and divergent construction of two types of valuable N-heterocycle is achieved easily, with the first example of the generation of α-oxo copper carbenes via copper-catalyzed oxidation of non-polarized alkynes.

Roles of Annexin A protein family in autophagy regulation and therapy

Annexin A is a kind of calcium-dependent phospholipid-binding proteins, which contributes to the formation of the cell membranes and cytoskeleton and played a part as a membrane skeleton to stabilize lipid bilayer. Autophagy is one of the most important programmed cell death mechanisms. And recently some reports suggest that annexin A family protein is associated with autophagy for annexin A can regulate the formation of vesicular lipid membranes and promote cell exocytosis. In this review, we summarized the roles of annexin A protein family in autophagy regulation and targeted medical treatment for better diagnoses and therapies.

Stereoselective, Multicomponent Approach to Quaternary Substituted Hydroindole Scaffolds

The Amaryllidaceae alkaloids have been a target of synthesis for decades due to their complex architectures and biological activity. A central feature of these natural product cores is a quaternary substituted hydroindole heterocycle. Building off the foundation of our previous multicomponent approach to highly functionalized pyrrolidinones, herein we report a highly convergent, diastereoselective, multicomponent approach to access the hydroindole cores present within crinine, haemanthamine, pretazettine, and various other bioactive alkaloids. These scaffolds are additionally useful as building blocks for druglike molecules and natural product like library generation.

S100 family proteins in inflammation and beyond

The S100 family proteins possess a variety of intracellular and extracellular functions. They interact with multiple receptors and signal transducers to regulate pathways that govern inflammation, cell differentiation, proliferation, energy metabolism, apoptosis, calcium homeostasis, cell cytoskeleton and microbial resistance. S100 proteins are also emerging as novel diagnostic markers for identifying and monitoring various diseases. Strategies aimed at targeting S100-mediated signaling pathways hold a great potential in developing novel therapeutics for multiple diseases. In this chapter, we aim to summarize the current knowledge about the role of S100 family proteins in health and disease with a major focus on their role in inflammatory conditions.

Oxidative cross-dehydrogenative [2 + 3] annulation of α-amino ketones with α-keto esters: concise synthesis of clausenamide analogues

A one-pot oxidative cross-dehydrogenative [2 + 3] annulation of α-amino ketones with α-keto esters at room temperature is reported.

S100A10 and Cancer Hallmarks: Structure, Functions, and its Emerging Role in Ovarian Cancer

S100A10, which is also known as p11, is located in the plasma membrane and forms a heterotetramer with annexin A2. The heterotetramer, comprising of two subunits of annexin A2 and S100A10, activates the plasminogen activation pathway, which is involved in cellular repair of normal tissues. Increased expression of annexin A2 and S100A10 in cancer cells leads to increased levels of plasmin—which promotes the degradation of the extracellular matrix—increased angiogenesis, and the invasion of the surrounding organs. Although many studies have investigated the functional role of annexin A2 in cancer cells, including ovarian cancer, S100A10 has been less studied. We recently demonstrated that high stromal annexin A2 and high cytoplasmic S100A10 expression is associated with a 3.4-fold increased risk of progression and 7.9-fold risk of death in ovarian cancer patients. Other studies have linked S100A10 with multidrug resistance in ovarian cancer; however, no functional studies to date have been performed in ovarian cancer cells. This article reviews the current understanding of S100A10 function in cancer with a particular focus on ovarian cancer.

Annexin A2 in Virus Infection

Viral life cycles consist of three main phases: (1) attachment and entry, (2) genome replication and expression, and (3) assembly, maturation, and egress. Each of these steps is intrinsically reliant on host cell factors and processes including cellular receptors, genetic replication machinery, endocytosis and exocytosis, and protein expression. Annexin A2 (AnxA2) is a membrane-associated protein with a wide range of intracellular functions and a recurrent host factor in a variety of viral infections. Spatially, AnxA2 is found in the nucleus and cytoplasm, vesicle-bound, and on the inner and outer leaflet of the plasma membrane. Structurally, AnxA2 exists as a monomer or in complex with S100A10 to form the AnxA2/S100A10 heterotetramer (A2t). Both AnxA2 and A2t have been implicated in a vast array of cellular functions such as endocytosis, exocytosis, membrane domain organization, and translational regulation through RNA binding. Accordingly, many discoveries have been made involving AnxA2 in viral pathogenesis, however, the reported work addressing AnxA2 in virology is highly compartmentalized. Therefore, the purpose of this mini review is to provide information regarding the role of AnxA2 in the lifecycle of multiple epithelial cell-targeting viruses to highlight recurrent themes, identify discrepancies, and reveal potential avenues for future research.

S100 proteins as therapeutic targets

The human genome codes for 21 S100 protein family members, which exhibit cell- and tissue-specific expression patterns. Despite sharing a high degree of sequence and structural similarity, the S100 proteins bind a diverse range of protein targets and contribute to a broad array of intracellular and extracellular functions. Consequently, the S100 proteins regulate multiple cellular processes such as proliferation, migration and/or invasion, and differentiation, and play important roles in a variety of cancers, autoimmune diseases, and chronic inflammatory disorders. This review focuses on the development of S100 neutralizing antibodies and small molecule inhibitors and their potential therapeutic use in controlling disease progression and severity.

Selective Synthesis of Diaryl Sulfoxides and m-Arylthio Sulfones from Arylsulfinic Acids and Arenes via BF3-Promoted C-S Bond Formation

A novel and efficient method for selective synthesis of diaryl sulfoxides and m-arylthio sulfones has been achieved from readily available arylsulfinic acids and arenes via an unusual sulfinyl cation, providing a range of structurally diverse products in good to excellent yields under mild conditions. Notably, mechanistic investigations suggested m-arylthio sulfones were generated from diaryl sulfoxides and sulfinyl cation by a sequence of redox reaction and electrophilic aromatic substitution process.

Regulation of von-Willebrand Factor Secretion from Endothelial Cells by the Annexin A2-S100A10 Complex

Endothelial cells serve as gatekeepers of vascular hemostasis and local inflammatory reactions. They can rapidly respond to changes in the environment, caused, for example, by blood vessel injury, tissue damage or infection, by secreting in a strictly regulated manner factors regulating these processes. These factors include adhesion receptors for circulating leukocytes and platelets, P-selectin and von-Willebrand factor (VWF) that are stored in specialized secretory granules of endothelial cells, the Weibel-Palade bodies (WPB). Acute exposure of these adhesion molecules converts the endothelial cell surface from an anti-adhesive state enabling unrestricted flow of circulating blood cells to an adhesive one capable of capturing leukocytes (through P-selectin) and platelets (through VWF). While these are important (patho)physiological responses, compromised or dysregulated WPB secretion can cause pathologies such as excessive bleeding or vascular occlusion. Several factors are involved in regulating the exocytosis of WPB and thus represent potential targets for therapeutic interventions in these pathologies. Among them, the annexin A2 (AnxA2)-S100A10 complex has been shown to participate in the tethering/docking of secretion-competent WPB at the plasma membrane, and interference with AnxA2/S100A10 expression or complex formation significantly reduces acute WPB exocytosis and VWF release. Thus, developing specific means to efficiently block AnxA2-S100A10 complex formation in endothelial cells could lead to novel avenues towards interfering with acute vascular thrombosis.

4-Aroyl-3-hydroxy-5-phenyl-1H-pyrrol-2(5H)-ones as N-formyl peptide receptor 1 (FPR1) antagonists

Formyl peptide receptors (FPRs) are expressed on a variety of leukocytes and play important roles in inflammation. Thus, FPR antagonists may represent novel therapeutics for modulating innate immunity and treating inflammatory diseases. Previously, 1H-pyrrol-2(5H)-ones were reported to be potent and competitive FPR1 antagonists. In the present studies, 42 additional 1H-pyrrol-2(5H)-one analogs were evaluated for FPR1 antagonist activity. We identified a number of novel competitive FPR1 antagonists that inhibited N-formylmethionyl-leucyl-phenylalanine (fMLF)-induced intracellular Ca2+ mobilization in FPR1-transfected HL60 cells and effectively competed with WKYMVm-FITC for binding to FPR1 in FPR1-transfected RBL cells. The most active pyrroles inhibited human neutrophil Ca2+ flux, chemotaxis, and adhesion to human epithelial cells, with the most potent being compounds 14 (4-benzoyl-1-hexyl-3-hydroxy-5-(4-hydroxy-3-methoxyphenyl)-2,5-dihydro-1H-pyrrol-2-one) and 17 (4-benzoyl-5-(2,5-dimethoxyphenyl)-3-hydroxy-1-(2-methoxyethyl)-2,5-dihydro-1H-pyrrol-2-one). In addition, these FPR1 antagonists inhibited fMLF-induced phosphorylation of extracellular signal-regulated kinases (ERK1/2) in FPR1-RBL cells, differentiated HL-60 cells, and human neutrophils. Most of the antagonists were specific for FPR1 and did not inhibit WKYMVM/WKYMVm-induced intracellular Ca2+ mobilization in FPR2-HL60 cells, FPR3-HL60 cells, or interleukin 8-induced Ca2+ flux in human neutrophils. Moreover, molecular modeling showed that the active pyrroles had a significantly higher degree of similarity with the FPR1 antagonist pharmacophore template as compared to inactive analogs. Thus, the 4-aroyl-3-hydroxy-5-phenyl-1H-pyrrol-2(5H)-one scaffold represents an important backbone for the development of novel FPR1 antagonists and could provide important clues for understanding the molecular structural requirements of FPR1 antagonists.

Stereoselective Synthesis of Quaternary Pyrrolidine-2,3-diones and β-Amino Acids

A facile, diastereoselective synthesis of highly substituted pyrrolidine-2,3-diones is reported, along with the one-step conversion of these heterocycles to novel β-amino acids and further functionalized derivatives. This method involves an unusually mild, one-pot, three-component cyclization/allylation followed by a Claisen rearrangement to provide unusual pyrrolidinone products that are densely functionalized and contain an all-carbon quaternary stereocenter. The reported reaction sequence is operationally simple, exquisitely diastereoselective, and provides gram-scale access to valuable heterocyclic scaffolds and β-amino acids not readily accessible via existing approaches.

Disruption of Annexin II /p11 Interaction Suppresses Leukemia Cell Binding, Homing and Engraftment, and Sensitizes the Leukemia Cells to Chemotherapy

The bone marrow microenvironment plays an important role in acute lymphoblastic leukemia (ALL) cell proliferation, maintenance, and resistance to chemotherapy. Annexin II (ANX2) is abundantly expressed on bone marrow cells and complexes with p11 to form ANX2/p11-hetero-tetramer (ANX2T). We present evidence that p11 is upregulated in refractory ALL cell lines and patient samples. A small molecule inhibitor that disrupts ANX2/p11 interaction (ANX2T inhibitor), an anti-ANX2 antibody, and knockdown of p11, abrogated ALL cell adhesion to osteoblasts, indicating that ANX2/p11 interaction facilitates binding and retention of ALL cells in the bone marrow. Furthermore, ANX2T inhibitor increased the sensitivity of primary ALL cells co-cultured with osteoblasts to dexamethasone and vincristine induced cell death. Finally, in an orthotopic leukemia xenograft mouse model, the number of ALL cells homing to the bone marrow was reduced by 40-50% in mice injected with anti-ANX2 antibody, anti-p11 antibody or ANX2T inhibitor compared to respective controls. In a long-term engraftment assay, the percentage of ALL cells in mouse blood, bone marrow and spleen was reduced in mice treated with agents that disrupt ANX2/p11 interaction. These data show that disruption of ANX2/p11 interaction results in reduced ALL cell adhesion to osteoblasts, increased ALL cell sensitization to chemotherapy, and suppression of ALL cell homing and engraftment.

State-of-the-art strategies for targeting protein-protein interactions by small-molecule inhibitors

Targeting protein-protein interactions (PPIs) has emerged as a viable approach in modern drug discovery. However, the identification of small molecules enabling us to effectively interrupt their interactions presents significant challenges. In the recent past, significant advances have been made in the development of new biological and chemical strategies to facilitate the discovery process of small-molecule PPI inhibitors. This review aims to highlight the state-of-the-art technologies and the achievements made recently in this field. The "hot spots" of PPIs have been proved to be critical for small molecules to bind. Three strategies including screening, designing, and synthetic approaches have been explored for discovering PPI inhibitors by targeting the "hot spots". Although the classic high throughput screening approach can be used, fragment screening, fragment-based drug design and newly improved virtual screening are demonstrated to be more effective in the discovery of PPI inhibitors. In addition to screening approaches, design strategies including anchor-based and small molecule mimetics of secondary structures involved in PPIs have become powerful tools as well. Finally, constructing new chemically spaced libraries with high diversity and complexity is becoming an important area of interest for PPI inhibitors. The successful cases from the recent five year studies are used to illustrate how these approaches are implemented to uncover and optimize small molecule PPI inhibitors and notably some of them have become promising therapeutics.

Small molecule inhibitors of the annexin A2 heterotetramer prevent human papillomavirus type 16 infection

OBJECTIVES

High-risk human papillomavirus (HPV) infection leads to the development of several human cancers that cause significant morbidity and mortality worldwide. HPV type 16 (HPV16) is the most common of the cancer-causing genotypes and gains entry to the basal cells of the epithelium through a non-canonical endocytic pathway that involves the annexin A2/S100A10 heterotetramer (A2t). A2t is composed of two annexin A2 monomers bound to an S100A10 dimer and this interaction is a potential target to block HPV16 infection. Here, recently identified small molecule inhibitors of A2t (A2ti) were investigated for their ability to prevent HPV16 infection in vitro.

METHODS

A2ti were added to HeLa cells in increasing concentrations prior to the addition of HPV16. Cytotoxicity was evaluated via trypan blue exclusion. HPV16 pseudovirion infection and fluorescently labelled HPV16 capsid internalization was measured with flow cytometry.

RESULTS

A2ti blocked HPV16 infection by 100% without substantial cellular toxicity or reduction in cell growth. Furthermore, A2ti blocked HPV16 entry into epithelial cells by 65%, indicating that the observed inhibition of HPV16 infection is in part due to a block in entry and that non-infectious entry may occur in the absence of A2t binding.

CONCLUSIONS

These results demonstrate that targeting A2t may be an effective strategy to prevent HPV16 infection.

An integrated biological approach to guide the development of metal-chelating inhibitors of influenza virus PA endonuclease

The influenza virus PA endonuclease, which cleaves capped cellular pre-mRNAs to prime viral mRNA synthesis, is a promising target for novel anti-influenza virus therapeutics. The catalytic center of this enzyme resides in the N-terminal part of PA (PA-Nter) and contains two (or possibly one or three) Mg(2+) or Mn(2+) ions, which are critical for its catalytic function. There is great interest in PA inhibitors that are optimally designed to occupy the active site and chelate the metal ions. We focused here on a series of β-diketo acid (DKA) and DKA-bioisosteric compounds containing different scaffolds, and determined their structure-activity relationship in an enzymatic assay with PA-Nter, in order to build a three-dimensional pharmacophore model. In addition, we developed a molecular beacon (MB)-based PA-Nter assay that enabled us to compare the inhibition of Mn(2+) versus Mg(2+), the latter probably being the biologically relevant cofactor. This real-time MB assay allowed us to measure the enzyme kinetics of PA-Nter or perform high-throughput screening. Several DKA derivatives were found to cause strong inhibition of PA-Nter, with IC50 values comparable to that of the prototype L-742,001 (i.e., below 2 μM). Among the different compounds tested, L-742,001 appeared unique in having equal activity against either Mg(2+) or Mn(2+). Three compounds ( 10: , with a pyrrole scaffold, and 40: and 41: , with an indole scaffold) exhibited moderate antiviral activity in cell culture (EC99 values 64-95 μM) and were proven to affect viral RNA synthesis. Our approach of integrating complementary enzymatic, cellular, and mechanistic assays should guide ongoing development of improved influenza virus PA inhibitors.

Hierarchical virtual screening approaches in small molecule drug discovery

Virtual screening has played a significant role in the discovery of small molecule inhibitors of therapeutic targets in last two decades. Various ligand and structure-based virtual screening approaches are employed to identify small molecule ligands for proteins of interest. These approaches are often combined in either hierarchical or parallel manner to take advantage of the strength and avoid the limitations associated with individual methods. Hierarchical combination of ligand and structure-based virtual screening approaches has received noteworthy success in numerous drug discovery campaigns. In hierarchical virtual screening, several filters using ligand and structure-based approaches are sequentially applied to reduce a large screening library to a number small enough for experimental testing. In this review, we focus on different hierarchical virtual screening strategies and their application in the discovery of small molecule modulators of important drug targets. Several virtual screening studies are discussed to demonstrate the successful application of hierarchical virtual screening in small molecule drug discovery.

Annexin A2 complexes with S100 proteins: structure, function and pharmacological manipulation

Annexin A2 (AnxA2) was originally identified as a substrate of the pp60v-src oncoprotein in transformed chicken embryonic fibroblasts. It is an abundant protein that associates with biological membranes as well as the actin cytoskeleton, and has been implicated in intracellular vesicle fusion, the organization of membrane domains, lipid rafts and membrane-cytoskeleton contacts. In addition to an intracellular role, AnxA2 has been reported to participate in processes localized to the cell surface including extracellular protease regulation and cell-cell interactions. There are many reports showing that AnxA2 is differentially expressed between normal and malignant tissue and potentially involved in tumour progression. An important aspect of AnxA2 function relates to its interaction with small Ca²⁺-dependent adaptor proteins called S100 proteins, which is the topic of this review. The interaction between AnxA2 and S100A10 has been very well characterized historically; more recently, other S100 proteins have been shown to interact with AnxA2 as well. The biochemical evidence for the occurrence of these protein interactions will be discussed, as well as their function. Recent studies aiming to generate inhibitors of S100 protein interactions will be described and the potential of these inhibitors to further our understanding of AnxA2 S100 protein interactions will be discussed.

Design, synthesis and SAR exploration of tri-substituted 1,2,4-triazoles as inhibitors of the annexin A2-S100A10 protein interaction

Recent target validation studies have shown that inhibition of the protein interaction between annexin A2 and the S100A10 protein may have potential therapeutic benefits in cancer. Virtual screening identified certain 3,4,5-trisubstituted 4H-1,2,4-triazoles as moderately potent inhibitors of this interaction. A series of analogues were synthesized based on the 1,2,4-triazole scaffold and were evaluated for inhibition of the annexin A2–S100A10 protein interaction in competitive binding assays. 2-[(5-{[(4,6-Dimethylpyrimidin-2-yl)sulfanyl]methyl}-4-(furan-2-ylmethyl)-4H-1,2,4-triazol-3-yl)sulfanyl]-N-[4-(propan-2-yl)phenyl]acetamide (36) showed improved potency and was shown to disrupt the native complex between annexin A2 and S100A10.

Significance of expression of PKCα, Annexin A2 and S100A10 proteins in gastric cancer

AIM: To investigate the clinical significance of expression of protein kinase C (PKC), Annexin A2 and S100A10 proteins in gastric cancer and provide valuable data for finding diagnosis related proteins in gastric cancer.

METHODS: The expression of PKCα, Annexin A2 and S100A10 proteins was detected by Western blot in normal gastric mucosa and gastric cancer tissues. Moreover, their expression was analyzed by immunohistochemistry in a tissue array containing normal gastric mucosa and gastric cancer tissues. The clinicopathologic significance of their expression was evaluated.

RESULTS: Western blot analysis showed that the expression of PKCα, Annexin A2 and S100A10 proteins was significantly higher in gastric cancer tissue than in normal gastric mucosa tissue (P < 0.01 for all). Immunohistochemistry analysis showed that the positive expression rates of PKCα, Annexin A2 and S100A10 proteins were significantly lower in normal gastric mucosa tissue than in gastric cancer tissue [8.82% (3/34) vs 76.54% (62/81), 5.88% (2/34) vs 79.01% (64/81), 2.94% (1/34) vs 59.26% (48/81); P < 0.01 for all].

CONCLUSION: The expression of PKCα, Annexin A2 and S100A10 proteins is up-regulated in gastric cancer tissue compared with normal gastric mucosa tissue and may be related with the occurrence and differentiation degree of gastric cancer.

3-aroylmethylene-2,3,6,7-tetrahydro-1H-pyrazino[2,1-a]isoquinolin-4(11bH)-ones as potent Nrf2/ARE inducers in human cancer cells and AOM-DSS treated mice

Nrf2-mediated activation of ARE regulates expression of cytoprotective enzymes against oxidative stress, inflammation, and carcinogenesis. We have discovered a novel structure (1) as an ARE inducer via luciferase reporter assay to screen the in-house database of our laboratory. The potency of 1 was evaluated by the expression of NQO-1, HO-1, and nuclear translocation of Nrf2 in HCT116 cells. In vivo potency of 1 was studied using AOM-DSS models, showing that the development of colorectal adenomas was significantly inhibited. Administration with 1 lowered the expression of IL-6, IL-1β, and promoted Nrf2 nuclear translocation. These results indicated that 1 is a potent Nrf2/ARE activator, both in vitro and in vivo. Forty-one derivatives were synthesized for SAR study, and a more potent compound 17 was identified. To our knowledge, this is a potent ARE activator. Besides, its novel structure makes it promising for further optimization.

Functions of S100 proteins

The S100 protein family consists of 24 members functionally distributed into three main subgroups: those that only exert intracellular regulatory effects, those with intracellular and extracellular functions and those which mainly exert extracellular regulatory effects. S100 proteins are only expressed in vertebrates and show cell-specific expression patterns. In some instances, a particular S100 protein can be induced in pathological circumstances in a cell type that does not express it in normal physiological conditions. Within cells, S100 proteins are involved in aspects of regulation of proliferation, differentiation, apoptosis, Ca2+ homeostasis, energy metabolism, inflammation and migration/invasion through interactions with a variety of target proteins including enzymes, cytoskeletal subunits, receptors, transcription factors and nucleic acids. Some S100 proteins are secreted or released and regulate cell functions in an autocrine and paracrine manner via activation of surface receptors (e.g. the receptor for advanced glycation end-products and toll-like receptor 4), G-protein-coupled receptors, scavenger receptors, or heparan sulfate proteoglycans and N-glycans. Extracellular S100A4 and S100B also interact with epidermal growth factor and basic fibroblast growth factor, respectively, thereby enhancing the activity of the corresponding receptors. Thus, extracellular S100 proteins exert regulatory activities on monocytes/macrophages/microglia, neutrophils, lymphocytes, mast cells, articular chondrocytes, endothelial and vascular smooth muscle cells, neurons, astrocytes, Schwann cells, epithelial cells, myoblasts and cardiomyocytes, thereby participating in innate and adaptive immune responses, cell migration and chemotaxis, tissue development and repair, and leukocyte and tumor cell invasion.

Protein interactions between surface annexin A2 and S100A10 mediate adhesion of breast cancer cells to microvascular endothelial cells

Annexin A2 (AnxA2) and S100A10 are known to form a molecular complex. Using fluorescence-based binding assays, we show that both proteins are localised on the cell surface, in a molecular form that allows mutual interaction. We hypothesized that binding between these proteins could facilitate cell-cell interactions. For cells that express surface S100A10 and surface annexin A2, cell-cell interactions can be blocked by competing with the interaction between these proteins. Thus an annexin A2-S100A10 molecular bridge participates in cell-cell interactions, revealing a hitherto unexplored function of this protein interaction.

In vivo screening of S100B inhibitors for melanoma therapy

S100 proteins are markers for numerous cancers, and in many cases high S100 protein levels are a prognostic indicator for poor survival. One such case is S100B, which is overproduced in a very large percentage of malignant melanoma cases. Elevated S100B protein was more recently validated to have causative effects towards cancer progression via down-regulating the tumor suppressor protein, p53. Towards eliminating this problem in melanoma, targeting S100B with small molecule inhibitors was initiated. This work relies on numerous chemical biology technologies including structural biology, computer-aided drug design, compound screening, and medicinal chemistry approaches. Another important component of drug development is the ability to test compounds and various molecular scaffolds for their efficacy in vivo. This chapter briefly describes the development of S100B inhibitors, termed SBiXs, for melanoma therapy with a focus on the inclusion of in vivo screening at an early stage in the drug discovery process.

A One-pot Multi-component Synthesis of N-aryl-3-aminodihydropyrrol-2-one-4-carboxylates Catalysed by Oxalic Acid Dihydrate

A simple synthesis of N-aryl-3-aminodihydropyrrol-2-one-4-carboxylates via one-pot multi-component reaction of amines, dialkyl acetylenedicarboxylates and formaldehyde in the presence of oxalic acid dihydrate (20 mol%) as catalyst in methanol is described. This homogeneous catalytic procedure offers advantages including mild reaction conditions, good to high yields, short reaction time, simple and readily available starting materials, easy work-up and there is no need for column chromatography.

Src kinase-induced phosphorylation of annexin A2 mediates glucocorticoid resistance in MLL-rearranged infant acute lymphoblastic leukemia

MLL-rearranged infant acute lymphoblastic leukemia (ALL) (<1 year of age) are frequently resistant to glucocorticoids, like prednisone and dexamethasone. As poor glucocorticoid responses are strongly associated with therapy failure, overcoming glucocorticoid resistance may be a crucial step towards improving prognosis. Unfortunately, the mechanisms underlying glucocorticoid resistance in MLL-rearranged ALL largely remain obscure. We here defined a gene signature that accurately discriminates between prednisolone-resistant and prednisolone-sensitive MLL-rearranged infant ALL patient samples, demonstrating that, among other genes, high-level ANXA2 is associated with prednisolone resistance in this type of leukemia. Further investigation demonstrated that the underlying factor of this association was the presence of Src kinase-induced phosphorylation (activation) of annexin A2, a process requiring the adapter protein p11 (encoded by human S100A10). shRNA-mediated knockdown of either ANXA2, FYN, LCK or S100A10, all led to inhibition of annexin A2 phosphorylation and resulted in marked sensitization to prednisolone. Likewise, exposure of prednisolone-resistant MLL-rearranged ALL cells to different Src kinase inhibitors exerting high specificity towards FYN and/or LCK had similar effects. In conclusion, we here present a novel mechanism of prednisolone resistance in MLL-rearranged leukemias, and propose that inhibition of annexin A2 phosphorylation embodies a therapeutic strategy for overcoming resistance to glucocorticoids in this highly aggressive type of leukemia.

Approach to the library of 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones through a three-component condensation

A convenient procedure for the parallel synthesis of 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones through a three-component condensation of active methylene compounds, aldehydes, and amines was developed. It was shown that the use of acetic acid as the reaction medium was suitable for the considerably reactive substrates with no additional functionalities. The substrates with low reactivity and those possessing carboxylic groups or additional basic centers required the use of DMF as the solvent and chlorotrimethylsilane as the reaction promoter was necessary. More than 3000 pyrrolones were synthesized by the developed procedure. To demonstrate the scope of the described approach 114 library representatives were fully characterized.

Enols as feasible acid components in the Ugi condensation

Heterocyclic enols are used for the first time as acid components in an Ugi-type multicomponent condensation. For that purpose, we have chosen enols containing a Michael acceptor, in order to facilitate an irreversible rearrangement of the primary Ugi adduct. The new four-component process leads readily and efficiently to heterocyclic enamines containing at least six elements of diversity.

Discovery, synthesis, and biological evaluation of orally active pyrrolidone derivatives as novel inhibitors of p53-MDM2 protein-protein interaction

The p53-MDM2 interaction has been proved to be a valuable target to develop effective antitumor agents. Novel p53-MDM2 inhibitors bearing pyrrolidone scaffolds were successfully identified by structure-based design. The nanomolar inhibitor 5 possessed good p53-MDM2 inhibitory activity (K(i) = 780 nM) due to its hydrophobic and hydrogen bonding interactions with MDM2. Further hit optimization led to the discovery of a number of highly potent pyrrolidone derivatives with improved p53-MDM2 inhibitory activity and in vitro antiproliferative potency. Compounds 41 (K(i) = 260.0 nM) and 60a (K(i) = 150.0 nM) showed good and selective activity against tumor cells with deleted p53. In addition, these two compounds also effectively inhibited the tumor growth in the A549 xenograft model. Interestingly, compound 41 was proved to be a potent MDM2/MDMX dual inhibitor. The novel pyrrolidone p53-MDM2 inhibitors represent promising lead structures for the development of novel antitumor agents.