Interaction of S100 proteins with the antiallergic drugs, olopatadine, amlexanox, and cromolyn: identification of putative drug binding sites on S100A1 protein

Benzopyrone, a privileged scaffold in drug discovery: An overview of FDA-approved drugs and clinical candidates

Natural products have always served as an important source of drugs for treating various diseases. Among various privileged natural product scaffolds, the benzopyrone class of compounds has a substantial presence among biologically active compounds. One of the pioneering anticoagulant drugs, warfarin approved in 1954 bears a benzo-α-pyrone (coumarin) nucleus. The widely investigated psoriasis drugs, methoxsalen, and trioxsalen, also contain a benzo-α-pyrone nucleus. Benzo-γ-pyrone (chromone) containing drugs, cromoglic acid, and pranlukast were approved as treatments for asthma in 1982 and 2007, respectively. Numerous other small molecules with a benzopyrone core are under clinical investigation. The present review discusses the discovery, absorption, distribution, metabolism, excretion properties, and synthetic approaches for the Food and Drug Administration-approved and clinical-stage benzopyrone class of compounds. The role of the pyrone core in biological activity has also been discussed. The present review unravels the potential of benzopyrone core in medicinal chemistry and drug development.

Degranulation of Murine Resident Cochlear Mast Cells: A Possible Factor Contributing to Cisplatin-Induced Ototoxicity and Neurotoxicity

Permanent hearing loss is one of cisplatin's adverse effects, affecting 30-60% of cancer patients treated with that drug. Our research group recently identified resident mast cells in rodents' cochleae and observed that the number of mast cells changed upon adding cisplatin to cochlear explants. Here, we followed that observation and found that the murine cochlear mast cells degranulate in response to cisplatin and that the mast cell stabilizer cromoglicic acid (cromolyn) inhibits this process. Additionally, cromolyn significantly prevented cisplatin-induced loss of auditory hair cells and spiral ganglion neurons. Our study provides the first evidence for the possible mast cell participation in cisplatin-induced damage to the inner ear.

S100 Proteins as Novel Therapeutic Targets in Psoriasis and Other Autoimmune Diseases

Psoriasis is one of the most common inflammatory skin diseases affecting about 1-3% of the population. One of the characteristic abnormalities in psoriasis is the excessive production of antimicrobial peptides and proteins, which play an essential role in the pathogenesis of the disease. Antimicrobial peptides and proteins can be expressed differently in normal and diseased skin, reflecting their usefulness as diagnostic biomarkers. Moreover, due to their very important functions in innate immunity, members of host defense peptides and proteins are currently considered to be promising new therapeutic targets for many inflammatory diseases. Koebnerisin (S100A15) belongs to an S100 family of antimicrobial proteins, which constitute the multigenetic group of calcium-binding proteins involved in ion-dependent cellular functions and regulation of immune mechanisms. S100A15 was first discovered to be overexpressed in 'koebnerized' psoriatic skin, indicating its involvement in the disease phenotype and the same promising potential as a new therapeutic target. This review describes the involvement of antimicrobial peptides and proteins in inflammatory diseases' development and therapy. The discussion focuses on S100 proteins, especially koebnerisin, which may be involved in the underlying mechanism of the Köebner phenomenon in psoriasis, as well as other immune-mediated inflammatory diseases described in the last decade.

S100 Proteins in Fatty Liver Disease and Hepatocellular Carcinoma

Non-alcoholic fatty liver disease (NAFLD) is a highly prevalent and slow progressing hepatic pathology characterized by different stages of increasing severity which can ultimately give rise to the development of hepatocellular carcinoma (HCC). Besides drastic lifestyle changes, few drugs are effective to some extent alleviate NAFLD and HCC remains a poorly curable cancer. Among the deregulated molecular mechanisms promoting NAFLD and HCC, several members of the S100 proteins family appear to play an important role in the development of hepatic steatosis, non-alcoholic steatohepatitis (NASH) and HCC. Specific members of this Ca²⁺-binding protein family are indeed significantly overexpressed in either parenchymal or non-parenchymal liver cells, where they exert pleiotropic pathological functions driving NAFLD/NASH to severe stages and/or cancer development. The aberrant activity of S100 specific isoforms has also been reported to drive malignancy in liver cancers. Herein, we discuss the implication of several key members of this family, e.g., S100A4, S100A6, S100A8, S100A9 and S100A11, in NAFLD and HCC, with a particular focus on their intracellular versus extracellular functions in different hepatic cell types. Their clinical relevance as non-invasive diagnostic/prognostic biomarkers for the different stages of NAFLD and HCC, or their pharmacological targeting for therapeutic purpose, is further debated.

Comprehensive analysis of the transcriptional expressions and prognostic value of S100A family in pancreatic ductal adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) remains a treatment-refractory malignancy with poor prognosis. It is urgent to identify novel and valid biomarkers to predict the progress and prognosis of PDAC. The S100A family have been identified as being involved in cell proliferation, migration and differentiation progression of various cancer types. However, the expression patterns and prognostic values of S100As in PDAC remain to be analyzed.

METHODS

We investigated the transcriptional expressions, methylation level and prognostic value of S100As in PDAC patients from the Oncomine, GEPIA2, Linkedomics and cBioPortal databases. Real-time PCR was used to detect the expressions of S100A2/4/6/10/14/16 in four pancreatic cancer cell lines and pancreatic cancer tissues from PDAC patients undergoing surgery. To verify the results further, immunohistochemistry was used to measure the expression of S100A2/4/6/10/14/16 in 43 PDAC patients' tissue samples. The drug relations of S100As were analyzed by using the Drugbank database.

RESULTS

The results suggested that, the expression levels of S100A2/4/6/10/14/16 were elevated to PDAC tissues than in normal pancreatic tissues, and the promoter methylation levels of S100A S100A2/4/6/10/14/16 in PDAC (n = 10) were lower compared with normal tissue (n = 184) (P < 0.05). In addition, their expressions were negatively correlated with PDAC patient survival.

CONCLUSIONS

Taken together, these results suggest that S100A2/4/6/10/14/16 might be served as prognostic biomarkers for survivals of PDAC patients.

Epigenetic programming underpins B-cell dysfunction in peanut and multi-food allergy

OBJECTIVE

Rates of IgE-mediated food allergy (FA) have increased over the last few decades, and mounting evidence implicates disruption of epigenetic profiles in various immune cell types in FA development. Recent data implicate B-cell dysfunction in FA; however, few studies have examined epigenetic changes within these cells.

METHODS

We assessed epigenetic and transcriptomic profiles in purified B cells from adolescents with FA, comparing single-food-allergic (peanut only), multi-food-allergic (peanut and ≥1 other food) and non-allergic (control) individuals. Adolescents represent a phenotype of persistent and severe FA indicative of a common immune deviation.

RESULTS

We identified 144 differentially methylated probes (DMPs) and 116 differentially expressed genes (DEGs) that distinguish B cells of individuals with FA from controls, including differential methylation of the PM20D1 promoter previously associated with allergic disorders. Subgroup comparisons found 729 DMPs specific to either single-food- or multi-food-allergic individuals, suggesting epigenetic distinctions between allergy groups. This included two regions with increased methylation near three S100 genes in multi-food-allergic individuals. Ontology results of DEGs specific to multi-food-allergic individuals revealed enrichment of terms associated with myeloid cell activation. Motif enrichment analysis of promoters associated with DMPs and DEGs showed differential enrichment for motifs recognised by transcription factors regulating B- and T-cell development, B-cell lineage determination and TGF-β signalling pathway between the multi-food-allergic and single-food-allergic groups.

CONCLUSION

Our data highlight epigenetic changes in B cells associated with peanut allergy, distinguishing features of the epigenome between single-food- and multi-food-allergic individuals and revealing differential developmental pathways potentially underpinning these distinct phenotypes.

Piperidine-Mediated [3 + 3] Cyclization of 2-Amino-4H-chromen-4-ones and 2-Benzylidenemalononitriles: To Access 2-Aminochromeno[2,3-b]pyridine Derivatives

Piperidine-mediated [3 + 3] cyclization of 2-amino-4H-chromen-4-ones and substituted 2-benzylidenemalononitriles was developed for the synthesis of 2-amino-4-aryl-5H-chromeno[2,3-b]pyridin-5-one derivatives. This novel transformation provides a highly efficient and facile route to functionalized 5H-chromeno[2,3-b]pyridines from readily available substrates under mild reaction conditions.

The S100 Protein Family as Players and Therapeutic Targets in Pulmonary Diseases

The S100 protein family consists of over 20 members in humans that are involved in many intracellular and extracellular processes, including proliferation, differentiation, apoptosis, Ca₂⁺ homeostasis, energy metabolism, inflammation, tissue repair, and migration/invasion. Although there are structural similarities between each member, they are not functionally interchangeable. The S100 proteins function both as intracellular Ca²⁺ sensors and as extracellular factors. Dysregulated responses of multiple members of the S100 family are observed in several diseases, including the lungs (asthma, chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, cystic fibrosis, pulmonary hypertension, and lung cancer). To this degree, extensive research was undertaken to identify their roles in pulmonary disease pathogenesis and the identification of inhibitors for several S100 family members that have progressed to clinical trials in patients for nonpulmonary conditions. This review outlines the potential role of each S100 protein in pulmonary diseases, details the possible mechanisms observed in diseases, and outlines potential therapeutic strategies for treatment.

Could calgranulins and advanced glycated end products potentiate acromegaly pathophysiology?

Growth hormone (GH) exerts a diverse set of effects across many tissues including fat, muscle, bone, kidney, heart, and liver. GH is also a diabetogenic hormone in that it inhibits the actions of insulin. Acromegaly, a condition traditionally characterized by increased levels of growth hormone secretion as a result of pituitary adenoma, results in increased tissue growth, lipolysis, and can result in patients with hyperglycemia and hyperinsulinemia. While current treatment modalities have greatly improved prognoses for most patients, a significant number present clinical symptoms of acromegaly with elevated levels of IGF-1 in the absence of increased GH levels, a phenomenon known as micromegaly. This condition presents a challenge to most currently used treatments since the high circulating IGF-1 levels are independent of elevated levels of GH. It has been previously shown that advanced glycation end products (AGE) can stimulate IGF-1 secretion by human monocytes in vitro, demonstrating a possible mechanism for increased IGF-1 levels. To further investigate AGE/GH/IGF-1 interaction, we have reanalyzed a publicly available RNAseq dataset from subcutaneous adipose tissue of patients with acromegaly. S100A1, a member of the calgranulin family of proteins and ligand of the AGE receptor, was shown to be significantly upregulated in patients with acromegaly. These findings identify an important consideration that may help explain the counterintuitive nature of micromegaly, while simultaneously providing new insight into the role of GH in diabetic, inflammatory, and immune pathologies.

Reviewing the Crystal Structure of S100Z and Other Members of the S100 Family: Implications in Calcium-Regulated Quaternary Structure

This paper takes the cue from the previously solved crystal structure of human apo-S100Z and compares it with that of the calcium-bound S100Z from zebrafish in order to stress, for this particular S100, the significant role of the presence of calcium in promoting supramolecular assemblies with likely biological meaning. This consideration is then expanded through a wider review on analogous situations concerning all other S100s for which there is crystallographic o biochemical evidence of how the presence of calcium promotes the formation of quaternary complexes.The paper also deals with some considerations on the quality of the crystals obtained for the solved members of this family and on the need for experimental phasing for solving some of the structures where the good general sequence homology among the members of the family would have suggested molecular replacement (MR) as the easiest way to solve them.These considerations, along with the PCA analysis carried out on all the known S100s, further demonstrate that calcium plays a fundamental role in triggering quaternary structure formation for several members of this family of proteins.

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.

Mast cells regulate myofilament calcium sensitization and heart function after myocardial infarction

Ngkelo et al. use a mast cell–deficient mouse model to reveal a protective role of mast cells in myocardial infarction, through regulation of the cardiac contractile machinery.

Acute myocardial infarction (MI) is a severe ischemic disease responsible for heart failure and sudden death. Inflammatory cells orchestrate postischemic cardiac remodeling after MI. Studies using mice with defective mast/stem cell growth factor receptor c-Kit have suggested key roles for mast cells (MCs) in postischemic cardiac remodeling. Because c-Kit mutations affect multiple cell types of both immune and nonimmune origin, we addressed the impact of MCs on cardiac function after MI, using the c-Kit–independent MC-deficient (Cpa3^Cre/+) mice. In response to MI, MC progenitors originated primarily from white adipose tissue, infiltrated the heart, and differentiated into mature MCs. MC deficiency led to reduced postischemic cardiac function and depressed cardiomyocyte contractility caused by myofilament Ca²⁺ desensitization. This effect correlated with increased protein kinase A (PKA) activity and hyperphosphorylation of its targets, troponin I and myosin-binding protein C. MC-specific tryptase was identified to regulate PKA activity in cardiomyocytes via protease-activated receptor 2 proteolysis. This work reveals a novel function for cardiac MCs modulating cardiomyocyte contractility via alteration of PKA-regulated force–Ca²⁺ interactions in response to MI. Identification of this MC-cardiomyocyte cross-talk provides new insights on the cellular and molecular mechanisms regulating the cardiac contractile machinery and a novel platform for therapeutically addressable regulators.

S100 proteins in cancer

In humans, the S100 protein family is composed of 21 members that exhibit a high degree of structural similarity, but are not functionally interchangeable. This family of proteins modulates cellular responses by functioning both as intracellular Ca(2+) sensors and as extracellular factors. Dysregulated expression of multiple members of the S100 family is a common feature of human cancers, with each type of cancer showing a unique S100 protein profile or signature. Emerging in vivo evidence indicates that the biology of most S100 proteins is complex and multifactorial, and that these proteins actively contribute to tumorigenic processes such as cell proliferation, metastasis, angiogenesis and immune evasion. Drug discovery efforts have identified leads for inhibiting several S100 family members, and two of the identified inhibitors have progressed to clinical trials in patients with cancer. This Review highlights new findings regarding the role of S100 family members in cancer diagnosis and treatment, the contribution of S100 signalling to tumour biology, and the discovery and development of S100 inhibitors for treating cancer.

S100P antibody-mediated therapy as a new promising strategy for the treatment of pancreatic cancer

Despite progresses in diagnosis and treatment, pancreatic cancer continues to have the worst prognosis of all solid malignant tumors. Recent evidences suggest that the metastasis-promoting protein S100P stimulates pancreatic tumor proliferation, survival, invasion and metastasis progression through extracellular functions. Moreover, its expression is strongly correlated with poor prognosis in patients with several types of cancer although the entire molecular mechanism responsible for the diverse biological functions is not fully understood. We showed that extracellular S100P stimulates pancreatic carcinoma BxPC3 cell line by promoting cell proliferation. We also demonstrated that S100P induces, in this cell line, the phosphorylation of IκBα and the secretion of matrix metalloproteinase 9 (MMP-9). In addition, treatment with S100P protected cells from injuries induced by the cytotoxic agent Gemcitabine. On the basis of these results, we developed function-blocking anti-S100P monoclonal antibodies (mAbs) that abolished all of its in vitro activities. Furthermore, in vivo treatment with the candidate 2H8 antibody decreased tumor growth and liver metastasis formation in a subcutaneous and orthotopic BxPC3 tumor model. We conclude here that a therapeutic strategy blocking the extracellular activity of S100P by means of specific mAbs could be an attractive therapeutic approach as a single agent or in combination with target-directed or chemotherapeutic drugs to treat pancreatic cancer.

Suramin is a novel activator of PP5 and biphasically modulates S100-activated PP5 activity

Suramin is an activator of ryanodine receptors and competitively binds to the calmodulin-binding site. In addition, S100A1 and calmodulin compete for the same binding site on ryanodine receptors. We therefore studied the effects of suramin on protein phosphatase 5 (PP5) and S100-activated PP5. In the absence of S100 proteins, suramin bound to the tetratricopeptide repeat (TPR) domain of PP5 and activated the enzyme in a dose-dependent manner. In the presence of S100A2/Ca(2+), lower concentrations of suramin dose-dependently inhibited PP5 activity as an S100 antagonist, whereas higher concentrations of suramin reactivated PP5. Although the C-terminal fragment of heat shock protein 90 (HspC90) also weakly activated PP5, the binding site of suramin and HspC90 may be different, and addition of suramin showed no clear effect on the phosphatase activity of PP5. Similar biphasic effects of suramin were observed with S100A1-, S100B- or S100P-activated PP5. However, the inhibitory effects of lower concentrations of suramin on S100A6-activated PP5 are weak and high concentrations of suramin further activated PP5. SPR and the cross-linking study showed inhibition of the interaction between S100 protein and PP5 by suramin. Our results revealed that suramin is a novel PP5 activator and modulates S100-activated PP5 activity by competitively binding to the TPR domain.

Solution structure and dynamics of human S100A14

Human S100A14 is a member of the EF-hand calcium-binding protein family that has only recently been described in terms of its functional and pathological properties. The protein is overexpressed in a variety of tumor cells and it has been shown to trigger receptor for advanced glycation end products (RAGE)-dependent signaling in cell cultures. The solution structure of homodimeric S100A14 in the apo state has been solved at physiological temperature. It is shown that the protein does not bind calcium(II) ions and exhibits a "semi-open" conformation that thus represents the physiological structure of the S100A14. The lack of two ligands in the canonical EF-hand calcium(II)-binding site explains the negligible affinity for calcium(II) in solution, and the exposed cysteines and histidine account for the observed precipitation in the presence of zinc(II) or copper(II) ions.

Evidence questioning cromolyn's effectiveness and selectivity as a 'mast cell stabilizer' in mice

Cromolyn, widely characterized as a 'mast cell stabilizer', has been used in mice to investigate the biological roles of mast cells in vivo. However, it is not clear to what extent cromolyn can either limit the function of mouse mast cells or influence biological processes in mice independently of effects on mast cells. We confirmed that cromolyn (at 10 mg/kg in vivo or 10-100 μM in vitro) can inhibit IgE-dependent mast cell activation in rats in vivo (measuring Evans blue extravasation in passive cutaneous anaphylaxis (PCA) and increases in plasma histamine in passive systemic anaphylaxis (PSA)) and in vitro (measuring peritoneal mast cell (PMC) β-hexosaminidase release and prostaglandin D(2) synthesis). However, under the conditions tested, cromolyn did not inhibit those mast cell-dependent responses in mice. In mice, cromolyn also failed to inhibit the ear swelling or leukocyte infiltration at sites of PCA. Nor did cromolyn inhibit IgE-independent degranulation of mouse PMCs induced by various stimulators in vitro. At 100 mg/kg, a concentration 10 times higher than that which inhibited PSA in rats, cromolyn significantly inhibited the increases in plasma concentrations of mouse mast cell protease-1 (but not of histamine) during PSA, but had no effect on the reduction in body temperature in this setting. Moreover, this concentration of cromolyn (100 mg/kg) also inhibited LPS-induced TNF production in genetically mast cell-deficient C57BL/6-Kit(W-sh/W-sh) mice in vivo. These results question cromolyn's effectiveness and selectivity as an inhibitor of mast cell activation and mediator release in the mouse.

Post-translational S-nitrosylation is an endogenous factor fine tuning the properties of human S100A1 protein

BACKGROUND

S100A1 protein is a proposed target of molecule-guided therapy for heart failure.

RESULTS

S-Nitrosylation of S100A1 is present in cells, increases Ca(2+) binding, and tunes the overall protein conformation.

CONCLUSION

Thiol-aromatic molecular switch is responsible for NO-related modification of S100A1 properties.

SIGNIFICANCE

Post-translational S-nitrosylation may provide functional diversity and specificity to S100A1 and other S100 protein family members. S100A1 is a member of the Ca(2+)-binding S100 protein family. It is expressed in brain and heart tissue, where it plays a crucial role as a modulator of Ca(2+) homeostasis, energy metabolism, neurotransmitter release, and contractile performance. Biological effects of S100A1 have been attributed to its direct interaction with a variety of target proteins. The (patho)physiological relevance of S100A1 makes it an important molecular target for future therapeutic intervention. S-Nitrosylation is a post-translational modification of proteins, which plays a role in cellular signal transduction under physiological and pathological conditions. In this study, we confirmed that S100A1 protein is endogenously modified by Cys(85) S-nitrosylation in PC12 cells, which are a well established model system for studying S100A1 function. We used isothermal calorimetry to show that S-nitrosylation facilitates the formation of Ca(2+)-loaded S100A1 at physiological ionic strength conditions. To establish the unique influence of the S-nitroso group, our study describes high resolution three-dimensional structures of human apo-S100A1 protein with the Cys(85) thiol group in reduced and S-nitrosylated states. Solution structures of the proteins are based on NMR data obtained at physiological ionic strength. Comparative analysis shows that S-nitrosylation fine tunes the overall architecture of S100A1 protein. Although the typical S100 protein intersubunit four-helix bundle is conserved upon S-nitrosylation, the conformation of S100A1 protein is reorganized at the sites most important for target recognition (i.e. the C-terminal helix and the linker connecting two EF-hand domains). In summary, this study discloses cysteine S-nitrosylation as a new factor responsible for increasing functional diversity of S100A1 and helps explain the role of S100A1 as a Ca(2+) signal transmitter sensitive to NO/redox equilibrium within cells.

CF2-containing acetylenephosphonates in heterocyclization reactions: the first synthesis of 2-difluoromethyl azaxanth-3-ylphosphonates

Acetylenephosphonates carrying the XCF(2) group have been studied in a base-mediated heterocyclization reaction with selected 2-amino-3-formylchromones to give 2-difluoromethyl azaxanth-3-ylphosphonates. The presence of the fluorinated substituent determined the regioselectivity as well as the reactivity of this process.

In vivo antitumor effect of cromolyn in PEGylated liposomes for pancreatic cancer

A PEGylated liposomal formulation of cromolyn, composed of dipalmitoylphosphatidylcholine (DPPC), dimyristoylphosphatidylcholine (DMPC), distearoylphosphatidylcholine (DSPC) and 1,2-distearoyl-sn-glycero-3-phospho-ethanolamine-N-[methoxy(polyethyleneglycol)-2000] (DSPE-mPEG2000), has been developed with the purpose of improving the antitumor activity of cromolyn for human pancreatic adenocarcinoma. In stability study, the amount of proteins adsorbed onto the PEGylated liposomes encapsulating cromolyn was 4.5-fold lower than the non-PEGylated liposome. In vitro study showed that the cromolyn in PEGylated liposome exhibited better anti-proliferative effect in BxPC-3 cells than in Panc-1 cells, which indicates higher level of endogenous S100P protein in BxPC-3 cells than in Panc-1 cells as a target protein for this drug. Moreover, the combination of cromolyn with gemcitabine in PEGylated liposomes demonstrated the strongest cytotoxicity to BxPC-3 pancreatic cancer cells in vitro and the highest anti-tumor activity against the BxPC-3 tumor bearing nude mice in vivo. Thus, this PEGylated liposomal formulation of cromolyn is expected to provide a novel approach to the treatment of pancreatic cancer in the future.

Regulation of nuclear localization signal-importin α interaction by Ca2+/S100A6

Although the precise intracellular roles of S100 proteins are not fully understood, these proteins are thought to be involved in Ca(2+)-dependent diverse signal transduction pathways. In this report, we identified importin α as a novel target of S100A6. Importin α contains armadillo repeats, essential for binding to nuclear localization signals. Based on the results from GST pull-down assay, gel-shift assay, and co-immunoprecipitation, we demonstrated that S100A6 specifically interacts with the armadillo repeats of importin α in a Ca(2+)-dependent manner, resulting in inhibition of the nuclear localization signal (NLS)-importin α complex formation in vitro and in vivo. These results indicate S100A6 may regulate the nuclear transport of NLS-cargos in response to increasing concentrations of intracellular Ca(2+).

S100P: a novel therapeutic target for cancer

S100P expression is described in many different cancers, and its expression is associated with drug resistance, metastasis, and poor clinical outcome. S100P is member of the S100 family of small calcium-binding proteins that have been reported to have either intracellular or extracellular functions, or both. Extracellular S100P can bind with the receptor for advanced glycation end products (RAGE) and activate cellular signaling. Through RAGE, S100P has been shown to mediate tumor growth, drug resistance, and metastasis. S100P is specifically expressed in cancer cells in the adult. Therefore, S100P is a useful marker for differentiating cancer cells from normal cells, and can aid in the diagnosis of cancer by cytological examination. The expression of S100P in cancer cells has been related to hypomethylation of the gene. Multiple studies have confirmed the beneficial effects of blocking S100P/RAGE in cancer cells, and different blockers are being developed including small molecules and antagonist peptides. This review summarizes the role and significance of S100P in different cancers.

The effect of asthma therapeutics on signalling and transcriptional regulation of airway smooth muscle function

SCOPE OF THE REVIEW

Our knowledge of the multifunctional nature of airway smooth muscle (ASM) has expanded rapidly in the last decade, but the underlying molecular mechanisms and how current therapies for obstructive airway diseases, such as asthma and chronic obstructive pulmonary disease (COPD), affect these are still being elucidated. Our current knowledge has built on the pharmacology of human ASM contraction and relaxation established prior to that and which is reviewed in detail elsewhere in this issue. The advent of methods to isolate and culture ASM cells, especially human ASM cells, has made it possible to study how they may contribute to airway remodelling through their synthetic, proliferative, and migratory capacities. Now the underlying molecular mechanisms of ASM growth factor secretion, extracellular matrix (ECM) production, proliferation and migration, as well as contraction and relaxation, are being determined. A complex network of signalling pathways leading to gene transcription in ASM cells permits this functional plasticity in healthy and diseased airways. This review is an overview of the effects of current therapies, and some of those in development, on key signalling pathways and transcription factors involved in these ASM functions.

Interactions of S100A2 and S100A6 with the tetratricopeptide repeat proteins, Hsp90/Hsp70-organizing protein and kinesin light chain

S100A2 and S100A6 interact with several target proteins in a Ca2+-regulated manner. However, the exact intracellular roles of the S100 proteins are unclear. In this study we identified Hsp70/Hsp90-organizing protein (Hop) and kinesin light chain (KLC) as novel targets of S100A2 and S100A6. Hop directly associates with Hsp70 and Hsp90 through the tetratricopeptide (TPR) domains and regulates Hop-Hsp70 and Hop-Hsp90 complex formation. We have found that S100A2 and S100A6 bind to the TPR domain of Hop, resulting in inhibition of the Hop-Hsp70 and Hop-Hsp90 interactions in vitro. Although endogenous Hsp70 and Hsp90 interact with Hop in resting Cos-7 cells, but not with S100A6, stimulation of these cells with ionomycin caused a Hop-S100A6 interaction, resulting in the dissociation of Hsp70 and Hsp90 from Hop. Similarly, glutathione S-transferase pulldown and co-immunoprecipitation experiments revealed that S100A6 binds to the TPR domain of KLC, resulting in inhibition of the KLC-c-Jun N-terminal kinase (JNK)-interacting protein 1 (JIP-1) interaction in vitro. The transiently expressed JIP-1 interacts with KLC in resting Cos-7 cells but not with S100A6. Stimulation of these cells with ionomycin also caused a KLC-S100A6 interaction, resulting in dissociation of JIP-1 from KLC. These results strongly suggest that the S100 proteins modulate Hsp70-Hop-Hsp90 multichaperone complex formation and KLC-cargo interaction via Ca2+-dependent S100 protein-TPR protein complex formation in vivo as well as in vitro. Moreover, we have shown that S100A2 and S100A6 interact with another TPR protein Tom70 and regulate the Tom70-ligand interaction in vitro. Thus, our findings suggest a new intracellular Ca2+-signaling pathway via S100 proteins-TPR motif interactions.

Structure of calcium-bound human S100A13 at pH 7.5 at 1.8 A resolution

S100A13 is a member of the S100 family of EF-hand-containing calcium-binding proteins. S100A13 plays an important role in the secretion of fibroblast growth factor-1 and interleukin 1 alpha, two pro-angiogenic factors released by the nonclassical endoplasmic reticulum/Golgi-independent secretory pathway. The X-ray crystal structure of human S100A13 at pH 7.5 was determined at 1.8 A resolution. The structure was solved by molecular replacement and was refined to a final R factor of 19.0%. The structure revealed that human S100A13 exists as a homodimer with two calcium ions bound to each protomer. The protomer is composed of four alpha-helices (alpha(1)-alpha(4)), which form a pair of EF-hand motifs. Dimerization occurs by hydrophobic interactions between helices alpha(1) and alpha(4) and by intermolecular hydrogen bonds between residues from helix alpha(1) and the residues between alpha(2) and alpha(3) of both chains. Despite the high similarity of the backbone conformation in each protomer, the crystal structures of human S100A13 at pH 7.5 (this study) and at pH 6.0 [Li et al. (2007), Biochem. Biophys. Res. Commun. 356, 616-621] exhibit recognizable differences in the relative orientation ( approximately 2.5 degrees) of the protomers within the dimer and also remarkable differences in the side-chain conformations of several amino-acid residues.

Olopatadine suppresses the migration of THP-1 monocytes induced by S100A12 protein

Olopatadine hydrochloride (olopatadine) is an antiallergic drug with histamine H(1) receptor antagonistic activity. Recently, olopatadine has been shown to bind to S100A12 which is a member of the S100 family of calcium-binding proteins, and exerts multiple proinflammatory activities including chemotaxis for monocytes and neutrophils. In this study, we examined the possibility that the interaction of olopatadine with S100A12 inhibits the proinflammatory effects of S100A12. Pretreatment of olopatadine with S100A12 reduced migration of THP-1, a monocyte cell line, induced by S100A12 alone, but did not affect recombinant human regulated upon activation, normal T cell expressed and secreted (RANTES)-induced migration. Amlexanox, which also binds to S100A12, inhibited the THP-1 migration induced by S100A12. However, ketotifen, another histamine H(1) receptor antagonist, had little effect on the activity of S100A12. These results suggest that olopatadine has a new mechanism of action, that is, suppression of the function of S100A12, in addition to histamine H(1) receptor antagonistic activity.

Effect of cromolyn on S100P interactions with RAGE and pancreatic cancer growth and invasion in mouse models

BACKGROUND

We previously found that S100P, a member of the S100 protein family, is expressed in more than 90% of pancreatic tumors and is associated with tumor growth and invasion. In the current study, we investigated the ability of the antiallergy drug, cromolyn, to block S100P function.

METHODS

Interactions between cromolyn and S100P were investigated using a drug affinity column and by examining cromolyn's effects on coimmunoprecipitation of S100P and receptor for advanced glycation end-products (RAGE). The effects of cromolyn on cell growth, invasion, and nuclear factor-kappaB (NFkappaB) activity of pancreatic cancer cells with (BxPC-3 and MPanc-96) and without (Panc-1) endogenous S100P were investigated by cell proliferation assay, by cell invasion assay, and by luciferase reporter gene assay, respectively. The effects of cromolyn on tumor growth in vivo were investigated in three orthotopic models (n = 20 mice per model) by administration of cromolyn (5 mg/kg body weight, daily) with and without gemcitabine (125 mg/kg body weight, biweekly), the drug currently used to treat pancreatic cancer. Tumor growth was assayed by reporter gene expression. All statistical tests were two-sided.

RESULTS

S100P was retained on a cromolyn affinity column. Cromolyn blocked the coimmunoprecipitation of S100P and RAGE. In vitro, cromolyn (100 microM) inhibited S100P-stimulated Panc-1 cell proliferation (S100P, mean = 0.93 U, versus S100P + cromolyn, mean = 0.56 U, difference = 0.37 U; 95% confidence interval [CI] = 0.24 to 0.49 U; P = .001, n = 3), invasion (S100P, mean = 58.0%, versus S100P + cromolyn, mean = 9.4%, difference = 48.6%; 95% CI = 38.8% to 58.8%; P<.001, n = 3), and NFkappaB activity (S100P, mean = 14,460, versus S100P + cromolyn, mean = 7360 photons/s, difference = 7100 photons/s; 95% CI = 3689 to 10 510 photons/s; P = .005, n = 3). In vivo, cromolyn inhibited tumor growth in mice bearing tumor with endogenous S100P (BxPC-3: control, mean = 1.6 x 10(9) photons/s, versus cromolyn, mean = 4.4 x 10(8) photons/s, difference = 1.2 x 10(9) photons/s; 95% CI = 6.2 x 10(8) to 1.6 x 10(9) photons/s; P<.001, n = 5; MPanc-96: control, mean = 1.1 x 10(10) photons/s, versus cromolyn, mean = 4.8 x 10(9) photons/s, difference = 6.2 x 10(9) photons/s; 95% CI = 1.9 x 10(9) to 1.0 x 10(10) photons/s; P = .009, n = 5) and increased the effectiveness of gemcitabine (BxPC-3: gemcitabine, mean = 9.2 x 10(8) photons/s, versus combination, mean = 1.8 x 10(8) photons/s, difference = 7.4 x 10(8) photons/s; 95% CI = 4.5 x 10(8) to 1.0 x 10(9) photons/s; P<.001; MPanc-96: gemcitabine, mean = 4.1 x 10(9) photons/s, versus combination, mean = 2.0 x 10(9) photons/s, difference = 2.1 x 10(9) photons/s; 95% CI = 4.4 x 10(8) to 3.8 x 10(9) photons/s; P<.001). However, cromolyn had no effect on growth of tumors lacking S100P (Panc-1).

CONCLUSION

Cromolyn binds S100P, prevents activation of RAGE, inhibits tumor growth, and increases the effectiveness of gemcitabine in experimental models.

Effect of an antiallergic drug (Olopatadine hydrochloride) on TARC/CCL17 and MDC/CCL22 production by PBMCs from patients with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by the predominant infiltration of Th2-type cells in lesional skin. Thymus and activation-regulated chemokine (TARC/CCL17) and monocyte-derived chemokine (MDC/CCL22) are Th2-type cytokines, and it has been reported that serum CCL17 and CCL22 levels are associated with AD disease activity. Olopatadine hydrochloride (Olopatadine) is an antiallergic drug with selective histamine H(1) receptor antagonist activity. The effect of Olopatadine on chemokine production by peripheral blood mononuclear cells (PBMCs) in AD patients has not been completely elucidated.

OBJECTIVES

This study was undertaken to clarify the effects of Olopatadine on CCL17 and CCL22 production by PBMCs from patients with AD during the treatment.

METHODS

We measured plasma levels of CCL17, CCL22, IFNgamma, IL-12 and IL-18 in 15 patients with AD before and after treatment with oral Olopatadine (10 mg/day) for 4 weeks. We also examined disease activity using SCORAD index, eosinophil numbers in peripheral blood and serum levels of LDH. PBMCs from the patients were taken before and after the treatment and cultured with or without dust mite allergen extract (DME) for 3 or 5 days. CCL17, CCL22, IFNgamma, IL-12 and IL-18 levels in the supernatants of cultured PBMCs were measured.

RESULTS

SCORAD index and eosinophil numbers in peripheral blood significantly decreased during treatment of AD patients with oral Olopatadine and topical corticosteroids for 4 weeks. The plasma levels of CCL17 and CCL22 significantly decreased after the treatment compared with before the treatment (p<0.05) and were significantly correlated with SCORAD index. PBMCs from AD patients taken after the treatment and cultured with DME for 5 days, showed significantly lower levels of CCL17 production than those taken before the treatment (p=0.018). PBMCs from AD patients taken after the treatment and cultured with DME for 5 days, also showed significantly lower levels of IFNgamma production than those taken before the treatment (p=0.012).

CONCLUSION

Our data demonstrate that Olopatadine inhibits CCL17 and CCL22 production by PBMCs from AD patients, which are important regulators of Th2 recruitment in the skin.

Identification of intracellular target proteins of the calcium-signaling protein S100A12

In this report, we have focused our attention on identifying intracellular mammalian proteins that bind S100A12 in a Ca2+-dependent manner. Using S100A12 affinity chromatography, we have identified cytosolic NADP+-dependent isocitrate dehydrogenase (IDH), fructose-1,6-bisphosphate aldolase A (aldolase), glyceraldehyde-3-phosphate dehydrogenese (GAPDH), annexin V, S100A9, and S100A12 itself as S100A12-binding proteins. Immunoprecipitation experiments indicated the formation of stable complexes between S100A12 and IDH, aldolase, GAPDH, annexin V and S100A9 in vivo. Surface plasmon resonance analysis showed that the binding to S100A12, of S100A12, S100A9 and annexin V, was strictly Ca2+-dependent, whereas that of GAPDH and IDH was only weakly Ca2+-dependent. To localize the site of S100A12 interaction, we examined the binding of a series of C-terminal truncation mutants to the S100A12-immobilized sensor chip. The results indicated that the S100A12-binding site on S100A12 itself is located at the C-terminus (residues 87-92). However, cross-linking experiments with the truncation mutants indicated that residues 87-92 were not essential for S100A12 dimerization. Thus, the interaction between S100A12 and S100A9 or immobilized S100A12 should not be viewed as a typical S100 homo- or heterodimerization model. Ca2+-dependent affinity chromatography revealed that C-terminal residues 75-92 are not necessary for the interaction of S100A12 with IDH, aldolase, GAPDH and annexin V. To analyze the functional properties of S100A12, we studied its action in protein folding reactions in vitro. The thermal aggregation of IDH or GAPDH was facilitated by S100A12 in the absence of Ca2+, whereas in the presence of Ca2+ the protein suppressed the aggregation of aldolase to less than 50%. These results suggest that S100A12 may have a chaperone/antichaperone-like function which is Ca2+-dependent.

S100A1 Is a Novel Molecular Chaperone and a Member of the Hsp70/Hsp90 Multichaperone Complex

Although calmodulin is known to be a component of the Hsp70/Hsp90 multichaperone complex, the functional role of the protein remains uncertain. In this study, we have identified S100A1, but not calmodulin or other S100 proteins, as a potent molecular chaperone and a new member of the multichaperone complex. Glutathione S-transferase pull-down assays and co-immunoprecipitation experiments indicated the formation of stable complexes between S100A1 and Hsp90, Hsp70, FKBP52, and CyP40 both in vitro and in mammalian cells. S100A1 potently protected citrate synthase, aldolase, glyceraldehyde-3-phosphate dehydrogenase, and rhodanese from heat-induced aggregation and suppressed the aggregation of chemically denatured rhodanese and citrate synthase during the refolding pathway. In addition, S100A1 suppressed the heat-induced inactivation of citrate synthase activity, similar to that for Hsp90 and p23. The chaperone activity of S100A1 was antagonized by calmodulin antagonists, such as fluphenazine and prenylamine, that is, indeed an intrinsic function of the protein. The overexpression of S100A1 in COS-7 cells protected transiently expressed firefly luciferase and Escherichia coli beta-galactosidase from inactivation during heat shock. The results demonstrate a novel physiological function for S100A1 and bring us closer to a comprehensive understanding of the molecular mechanisms of the Hsp70/Hsp90 multichaperone complex.

Terfenadine antagonism against interleukin-4-modulated gene expression of T cell cytokines

Here, we investigated whether an anti-allergy drug, terfenadine, affects interleukin-4-modulated cytokine expression in peripheral T cells. Peripheral blood T cells were first stimulated with recombinant interleukin-4 and then tested for modulation of the mRNA of a panel of cytokines using the reverse transcription-polymerase chain reaction followed by Southern blot analysis. It was found that T cells constitutively expressed mRNA specific to T helper 1 cytokines (interleukin-2, interferon-gamma, tumor necrosis factor-alpha), which was markedly downregulated upon stimulation with interleukin-4, whereas mRNA for T helper 2 cytokines such as interleukins 4, 5, and 6 was induced in response to interleukin-4. Interestingly, the interleukin-4-induced expression of all T helper 2 cytokines examined was markedly downregulated by terfenadine. Among T helper 1 cytokines, interleukin-4-mediated suppression of tumor necrosis factor-alpha was not affected by terfenadine, which, however, markedly restored mRNA expression of interferon-gamma or interleukin-2. Electrophoretic mobility shift assays using [32P]-labeled synthetic oligonucleotides encoding the consensus binding motif of activator protein-1 demonstrated that interleukin-4-induced binding of activator protein-1 composed of JunB was interfered by terfenadine. This study indicates that terfenadine, at least partially, interferes with interleukin-4-activated signaling, leading to terfenadine antagonism against the modulatory impact of interleukin-4 on T cell cytokines.

Anti-allergic drug olopatadine suppresses murine contact hypersensitivity and downmodulates antigen-presenting ability of epidermal Langerhans cells

Olopatadine hydrochloride is an H1-receptor-blocker but has other anti-allergic pharmacological potencies. We investigated whether olopatadine inhibits murine contact hypersensitivity, focussing on its modulatory action on epidermal Langerhans cells serving as antigen-presenting cells. While BALB/c mice were sensitized and challenged epicutaneously with hapten, they were administered intraperitoneally with olopatadine. Olopatadine at 1 or 0.2 mg/kg of weight significantly suppressed the sensitivity when injected at least once before sensitization or challenge. In olopatadine-injected mice, the ability of Langerhans cells to present hapten to primed T cells was reduced with decreased expression of MHC class II and co-stimulatory molecules. Langerhans cells exposed in vitro to 10(-5) or 10(-6) M olopatadine had less antigen-presenting activity than control, whereas neither T cell proliferation nor keratinocyte production of IL-1alpha and IP-10 was affected at these doses. These findings suggest that olopatadine downmodulates contact hypersensitivity at least partly by interfering with the antigen-presenting ability of Langerhans cells.

Molecular mechanisms of S100-target protein interactions

S100 proteins have no known enzymatic activity and exert their intracellular effects via interaction with and regulation of the activity of other proteins, termed target proteins, in both a Ca(2+)-dependent and Ca(2+)-independent manner. Structural studies have identified the linker region between the two EF-hand Ca(2+) binding domains and the C-terminus as Ca(2+)-dependent target protein binding sites in several S100 family members. In fact, C-terminal aromatic residues are obligatory for interaction of S100A1 with several of its Ca(2+)-dependent target proteins. Pharmacological studies suggest the presence of additional Ca(2+)-dependent binding motifs on some family members. A minimum of seven family members interact with and regulate the activity of aldolase A in a Ca(2+)-independent manner. In the case of S100A1, Ca(2+)-independent target protein interactions utilize a binding motif distinct from the C-terminal Ca(2+)-dependent target protein binding site. Several studies suggest that ionic interactions participate in the interaction of S100 family members with Ca(2+)-independent target proteins. While some target proteins are activated by multiple family members, other target proteins exhibit family member-specific activation, i.e., they are activated by a single family member. As predicted, family member specific interactions appear to be mediated by regions that exhibit the most divergence in amino acid sequence among family members, the linker or "hinge" region and the C terminus. Further specificity in S100-target protein interactions may arise from the different biochemical/biophysical properties of the individual family members, including affinity for metal ions (Ca(2+), Zn(2+), and Cu(2+)), oligomerization properties, heterodimerization, post-translational modifications, and lipid-binding. Delineation of the structural motifs that mediate S100-target protein interactions and determination of the in vivo relevance of these interactions are needed to fully understand the role of S100 proteins in normal and diseased cells.