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Hypoxia is characterized by an inadequate supply of oxygen to tissues, and hypoxic regions are commonly found in solid tumors. The cellular response to hypoxic conditions is mediated through the activation of hypoxia-inducible factors (HIFs) that control the expression of a large number of target genes. Recent studies have shown that the receptor for advanced glycation end products (RAGE) participates in hypoxia-dependent cellular adaptation. We review recent evidence on the role of RAGE signaling in tumor biology under hypoxic conditions.

Pancreatic ductal adenocarcinoma (PDAC) remains a very difficult cancer to treat. Recent in vitro and in vivo studies suggest that the activation of the receptor for advanced glycation end products (RAGE) by its ligands stimulates pancreatic cancer cell proliferation and tumor growth. Additional studies show that, in the RAGE ligand, the high mobility group box 1 (HMGB1) protein plays an important role in chemoresistance against the cytotoxic agent gemcitabine by promoting cell survival through increased autophagy. We hypothesized that blocking the RAGE/HMGB1 interaction would enhance the cytotoxic effect of gemcitabine by reducing cell survival and autophagy. Using a preclinical mouse model of PDAC and a monoclonal antibody (IgG 2A11) as a RAGE inhibitor, we demonstrate that RAGE inhibition concurrent with gemcitabine treatment enhanced the cytotoxic effect of gemcitabine. The combination of IgG 2A11 and gemcitabine resulted in decreased autophagy compared to treatment with gemcitabine combined with control antibodies. Notably, we also observed that RAGE inhibition protected against excessive weight loss during treatment with gemcitabine. Our data suggest that the combination of gemcitabine with a RAGE inhibitor could be a promising therapeutic approach for the treatment of pancreatic cancer and needs to be further investigated.

The receptor for advanced glycation end products (RAGE) contributes to many cellular aspects of pancreatic cancer including cell proliferation, migration, and survival. Studies have shown that RAGE activation by its ligands promotes pancreatic tumor growth by stimulating both cell proliferation and migration. In this study, we investigated the effect of RAGE up-regulation on the proliferation and migration of the human pancreatic cancer Panc-1 cell-line. We show that moderate overexpression of RAGE in Panc-1 cells results in increased cell proliferation, but decreased cell migration. The observed cellular changes were confirmed to be RAGE-specific and reversible by using RAGE-specific siRNAs and the small molecule RAGE inhibitor FPS-ZM1. At the molecular level, we show that RAGE up-regulation was associated with decreased activity of FAK, Akt, Erk1/2, and NF-&kappa, B signaling pathways and greatly reduced levels of &alpha, 2 and &beta, 1 integrin expression, which is in agreement with the observed decreases in cell migration. We also demonstrate that RAGE up-regulation changes the expression of key molecular markers of epithelial-to-mesenchymal transition (EMT). Our results suggest that in the absence of stimulation by external ligands, RAGE up-regulation can differently modulate cell proliferation and migration in pancreatic cancer cells and regulates partly EMT.

The receptor for advanced glycation end products (RAGE) recognizes damage-associated molecular patterns (DAMPs) and plays a critical role for the innate immune response and sterile tissue inflammation. RAGE overexpression is associated with diabetic complications, neurodegenerative diseases and certain cancers. Yet, the molecular mechanism of ligand recognition by RAGE is insufficiently understood to rationalize the binding of diverse ligands. The N-terminal V-type Ig-domain of RAGE contains a triad of tryptophan residue; Trp51, Trp61 and Trp72. The role of these three Trp residues for domain folding, stability and binding of the RAGE ligand S100B was investigated through site-directed mutagenesis, UV/VIS, CD and fluorescence spectrometry, protein–protein interaction studies, and X-ray crystallography. The data show that the Trp triad stabilizes the folded V-domain by maintaining a short helix in the structure. Mutation of any Trp residue increases the structural plasticity of the domain. Residues Trp61 and Trp72 are involved in the binding of S100B, yet they are not strictly required for S100B binding. The crystal structure of the RAGE-derived peptide W72 in complex with S100B showed that Trp72 is deeply buried in a hydrophobic depression on the S100B surface. The studies suggest that multiple binding modes between RAGE and S100B exist and point toward a not previously recognized role of the Trp residues for RAGE-ligand binding. The Trp triad of the V-domain appears to be a suitable target for novel RAGE inhibitors, either in the form of monoclonal antibodies targeting this epitope, or small organic molecules.

Despite recent progresses in its treatment, malignant cutaneous melanoma remains a cancer with very poor prognosis. Emerging evidences suggest that the receptor for advance glycation end products (RAGE) plays a key role in melanoma progression through its activation in both cancer and stromal cells. In tumors, RAGE activation is fueled by numerous ligands, S100B and HMGB1 being the most notable, but the role of many other ligands is not well understood and should not be underappreciated. Here, we provide a review of the current role of RAGE in melanoma and conclude that targeting RAGE in melanoma could be an approach to improve the outcomes of melanoma patients.

CD34+ hematopoietic stem/progenitor cells (HSPCs) are vasculogenic and hypoxia is a strong stimulus for the vasoreparative functions of these cells. Angiotensin-converting enzyme 2 (ACE2)/angiotensin-(1-7)/Mas receptor (MasR) pathway stimulates vasoprotective functions of CD34+ cells. This study tested if ACE2 and MasR are involved in the hypoxic stimulation of CD34+ cells. Cells were isolated from circulating mononuclear cells derived from healthy subjects (n = 46) and were exposed to normoxia (20% O2 ) or hypoxia (1% O2 ). Luciferase reporter assays were carried out in cells transduced with lentivirus carrying ACE2- or MasR- or a scramble-3'-untranslated region gene with a firefly luciferase reporter. Expressions or activities of ACE, angiotensin receptor Type 1 (AT1R), ACE2, and MasR were determined. In vitro observations were verified in HSPCs derived from mice undergoing hindlimb ischemia (HLI). In vitro exposure to hypoxia-increased proliferation and migration of CD34+ cells in basal conditions or in response to vascular endothelial growth factor (VEGF) or stromal-derived factor 1α (SDF) compared with normoxia. Expression of ACE2 or MasR was increased relative to normoxia while ACE or AT1R expressions were unaltered. Luciferase activity was increased by hypoxia in cells transfected with the luciferase reporter plasmids coding for the ACE2- or MasR promoters relatively to the control. The effects of hypoxia were mimicked by VEGF or SDF under normoxia. Hypoxia-induced ADAM17-dependent shedding of functional ACE2 fragments. In mice undergoing HLI, increased expression/activity of ACE2 and MasR were observed in the circulating HSPCs. This study provides compelling evidence for the hypoxic upregulation of ACE2 and MasR in CD34+ cells, which likely contributes to vascular repair.

CD34 + stem/progenitor cells have the propensity of re-endothelialization and vascular regeneration. Angiotensin Converting Enzyme-2 (ACE2) generates Angiotensin (Ang)-(1-7), which produces vasoprotection by acting on Mas receptor (MasR). Hypoxic preconditioning has been shown to stimulate vascular repair-relevant functions of CD34 + cells, which was impaired in MasR-deficient HSPCs. The current study tested the hypothesis that hypoxic stimulation of CD34 + cell functions are mediated by ACE2 and MasR. CD34 + cells were isolated from mononuclear cells (MNCs) derived from healthy volunteers (n=46). Cells were exposed to normoxia (20% O 2 ) or hypoxia (1% O 2 ). Protein and mRNA expressions of ACE2 and MasR were determined. ACE2 activity was determined by using an enzyme-specific fluorogenic substrate, and a selective inhibitor, MLN4760. CD34 + cells were transduced with lentiviral particles carrying ACE2- or MasR- or scramble-3’-UTR (Scr) fused downstream to firefly luciferase reporter (flr) gene. Co-transfection luciferase assay was performed using MicroRNA, miR-421 or miR-143 with ACE-2 or MasR luciferase construct, respectively. Luciferase activity was determined by using luciferase assay kit. Hypoxia stimulated mRNA and protein expressions of ACE2 and MasR in CD34 + cells (54.9±4.8% and 51.6±14.7%, respectively, higher than normoxia, n=5, P+ cells, which contribute to their vasoreparative functions.

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with low survival rates. Current therapeutic treatments have very poor response rates due to the high inherent chemoresistance of the pancreatic-cancer cells. Recent studies have suggested that the receptor for advanced glycation end products (RAGE) and its S100 protein ligands play important roles in the progression of PDAC. We will discuss the potential role of S100 proteins and their receptor, RAGE, in the development and progression of pancreatic cancer.

Liposomes are representative lipid nanoparticles widely used for delivering anticancer drugs, DNA fragments, or siRNA to cancer cells. Upon targeting, various internal and external triggers have been used to increase the rate for contents release from the liposomes. Among the internal triggers, decreased pH within the cellular lysosomes has been successfully used to enhance the rate for releasing contents. However, imparting pH sensitivity to liposomes requires the synthesis of specialized lipids with structures that are substantially modified at a reduced pH. Herein, we report an alternative strategy to render liposomes pH sensitive by encapsulating a precursor which generates gas bubbles in situ in response to acidic pH. The disturbance created by the escaping gas bubbles leads to the rapid release of the encapsulated contents from the liposomes. Atomic force microscopic studies indicate that the liposomal structure is destroyed at a reduced pH. The gas bubbles also render the liposomes echogenic, allowing ultrasound imaging. To demonstrate the applicability of this strategy, we have successfully targeted doxorubicin-encapsulated liposomes to the pancreatic ductal carcinoma cells that overexpress the folate receptor on the surface. In response to the decreased pH in the lysosomes, the encapsulated anticancer drug is efficiently released. Contents released from these liposomes are further enhanced by the application of continuous wave ultrasound (1 MHz), resulting in substantially reduced viability for the pancreatic cancer cells (14%).

The ability to map multiple biomarkers at the same time has far-reaching biomedical and diagnostic applications. Here, a series of biocompatible poly(D,L-lactic-co-glycolic acid) and polyethylene glycol particles for multicolor and multiplexed imaging are reported. More than 30 particle formulations that exhibit distinct emission signatures (ranging from the visible to NIR wavelength region) are designed and synthesized. These particles are encapsulated with combinations of carbocyanine-based fluorophores DiO, Dil, DiD, and DiR, and are characterized as

The use of plant derived polysaccharides as health promoters has gained immense interest in the past few years. Arabinoxylan (AX) is the predominant non-starch polysaccharide in cereals and grasses including wheat. The current research aimed to investigate the structure-function relationship of arabinoxylan hydrolyzates (AXH), obtained by the enzymatic hydrolysis of AX using xylanase and arabinofuranosidase as immunomodulators in two colon cancer cell lines: Caco-2 and HT-29. Fine structural details had a strong correlation with the immunological properties of the wheat AXH. As a general trend, as the presence of arabinose substitution increased in the AXH, the production of proinflammatory cytokines, IL-8 and TNF-α, decreased in both cell lines. Thus, AXH with a higher degree of arabinose substitution might be better adept in lowering inflammation in colon cancer cells.

Inflammation is an important healthy immune response of the body during lesions and infection. However, uncontrolled excessive inflammation can be damaging to the cells. The specific objective of this research was to evaluate the effect of structural details of enzymatically derived wheat arabinoxylan hydrolyzates (AXH) on their immunomodulatory properties. Out of the 30 AXH, six AXH showed statistically significant reduction in NO production compared to the control, causing an approximately 24 to 12% reduction in NO production. Five AXH exhibited statistically significant pro-inflammatory properties in the LPS induced cells, causing an approximately 10 to 14% increase compared to the control. A negative correlation was seen between NO production and total arabinoxylan (AX) × amount of 1,4-linked xylose with arabinose substituted at the O-3 position. Thus, AXH with higher AX and substitution at the O-3 position are favorable candidates to reduce the lipopolysaccharide induced inflammation. These results suggest that there may be a structure-function relationship for these AXH as immunomodulators.

Physiologically relevant reactive carbonyl compounds vary greatly in their glycation reactivity and the resulting advanced glycation endproducts (AGE) are likely to have distinct structural and biological properties. We characterized a panel of twenty AGE-BSA preparations in terms of (i) their biophysical properties, (ii) their binding to the receptor for advanced glycation endproducts (RAGE) and galectin-3, and (iii) their effects on cellular proliferation. We could establish correlations between lysine glycation and changes in secondary structure. Circular dichroism and differential scanning calorimetry experiments showed that glycation causes albumin to adopt folding properties of a molten globule. Binding studies between AGE-albumin and RAGE or galectin-3 indicate that binding to the isolated receptor domains was weak. Only AGE compounds derived by glycation with ribose were able to bind tightly (K(d) < 10 μM) to both AGE receptors. Cell based assays using an engineered melanoma cell line demonstrated correlations between the extent of (i) lysine side chain modification, (ii) β-sheet content and (iii) albumin multimerization with stimulation of cell proliferation. However, in addition to structural properties of the protein, the chemical structures of the AGE-modifications were important for receptor binding and biological activity as well.

Cereal derived arabinoxylans (AX) have been shown to possess immunomodulatory properties. However, AX are complex molecules that can exist with different degree of polymerization (DP) and degree of arabinose substitution (DS). We investigated the effect of these structural differences on the immunomodulatory property of xylo-oligosaccharides (XOS), arabinoxylo-oligosaccharides (AXOS) and AX polysaccharides. We investigated the effect of these substrates on RAW264.7 cells with respect to nitric oxide (NO) and TNF-α production. XOS did not display an immunomodulatory activity with respect to NO production except for X3, which decreased NO production compared to control. AXOS which contained arabinose substitution were better capable of decreasing NO production in macrophages. AX polysaccharides on the other hand were inducers of NO production acting as inmmunostimulators. High molecular weight AX polysaccharide (AX H) was immunostimulators with respect to TNF-α production as well. AX H also displayed a dose dependent relationship with TNF-α production in RAW264.7 cells. These results suggest that exploring high molecular weight AX polysaccharides as immunomodulators could be beneficial compared to smaller molecular weight unsubstituted oligosaccharides.

In the genesis of Alzheimer's disease (AD), converging lines of evidence suggest that amyloid-β peptide (Aβ) triggers a pathogenic cascade leading to neuronal loss. It was long assumed that Aβ had to be assembled into extracellular amyloid fibrils or aggregates to exert its cytotoxic effects. Over the past decade, characterization of soluble oligomeric Aβ species in the brains of AD patients and in transgenic models has raised the possibility that different conformations of Aβ may contribute to AD pathology via different mechanisms. The receptor for advanced glycation end products (RAGE), a member of the Ig superfamily, is a cellular binding site for Aβ. Here, we investigate the role of RAGE in apoptosis induced by distinct well characterized Aβ conformations: Aβ oligomers (AβOs), Aβ fibrils (AβFs), and Aβ aggregates (AβAs). In ourin vitrosystem, treatment with polyclonal anti-RAGE antibodies significantly improves SHSY-5Y cell and neuronal survival exposed to either AβOs or AβAs but does not affect AβF toxicity. Interestingly, using site-specific antibodies, we demonstrate that targeting of the Vddomain of RAGE attenuates AβO-induced toxicity in both SHSY-5Y cells and rat cortical neurons, whereas inhibition of AβA-induced apoptosis requires the neutralization of the C1ddomain of the receptor. Thus, our data indicate that distinct regions of RAGE are involved in Aβ-induced cellular and neuronal toxicity with respect to the Aβ aggregation state, and they suggest the blockage of particular sites of the receptor as a potential therapeutic strategy to attenuate neuronal death.

The prion protein, and an increasing number of other cellular proteins, can undergo conformational transitions leading to soluble oligomers and insoluble aggregates. We have previously shown that the transition of the prion protein from its native form to its infectious (PrP(Sc)) conformation can be monitored with epitope specific antibodies while the protein is immobilized on the surface of a Biacore surface plasmon resonance sensor chip. (Leclerc et al EMBO J 20:1547-1554 2001). The folding pathways leading to insoluble aggregates (amyloids) and soluble oligomers are believed to be distinct. We report here the use of epitope-specific antibody Fab fragments and surface plasmon resonance measurements on immobilized PrP to investigate the conditions leading to either folding pathway. We found that full-length SHaPrP(29-231) and truncated SHaPrP(90-231) prion protein can be induced to undergo the transition to proteinase K-resistant PrP(Sc) aggregates on a sensor chip. This transition is temperature and buffer dependent and can be blocked by the presence of antibody Fab fragments binding to epitopes important for the conformational change. We demonstrate that the use of monoclonal antibodies combined with surface plasmon resonance technology is suitable to monitor the environmental conditions leading to conformational changes in the prion protein. The methodology is applicable to other amyloid- and oligomer-forming proteins and should be useful for the evaluation of antibodies or small molecules preventing protein misfolding.

Patients with metastatic melanoma still experience poor prognosis despite the recent approval of new therapeutic agents. It is therefore essential to continue searching for new therapeutic targets and approaches. In recent year, studies have suggested that the receptor for advanced glycation end products (RAGE) could be a potential therapeutic target in metastatic melanoma. Animal studies have shown that blocking RAGE with targeted antibodies could reduce tumor growth and metastases formation. We will discuss here evidence suggesting that RAGE and its ligands contribute significantly to metastatic melanoma and that blocking RAGE activation could be a valid approach for treating this disease.

The receptor for advanced glycation end products (RAGE) is an important cell surface receptor being pursued as a therapeutic target because it has been implicated in complications arising from diabetes and chronic inflammatory conditions. RAGE is a single membrane spanning receptor containing a very small approximately 40 residue cytosolic domain and a large extracellular region composed of 3 Ig-like domains. In this study, high level bacterial expression systems and purification protocols were generated for the extracellular region of RAGE (sRAGE) and the five permutations of single and tandem domain constructs to enable biophysical and structural characterization of its tertiary and quaternary structure. The structure and stability of each of these six protein constructs was assayed by biochemical methods including limited proteolysis, dynamic light scattering, CD, and NMR. A homology model of sRAGE was constructed to aid in the interpretation of the experimental data. Our results show that the V and C1 domains are not independent domains, but rather form an integrated structural unit. In contrast, C2 is attached to VC1 by a flexible linker and is fully independent. The interaction with a known RAGE ligand, Ca2+-S100B, was mapped to VC1, with the major contribution from the V domain but clearly defined secondary effects from the C1 domain. The implications of these results are discussed with respect to models for RAGE signaling.

Arabinoxylan (AX) is a non-starch polysaccharide found in many cereal grains and is considered as a dietary fiber. Despite their general structure, there is structural heterogeneity among AX originating from different botanical sources. Furthermore, the extraction procedure and hydrolysis by xylolytic enzymes can further render differences to theses AX. The aim of this review was to address the effects of AX on the gut bacteria and their immunomodulatory properties. Given the complex structure of AX, we also aimed to discuss how the structural heterogeneity of AX affects its role in bacterial growth and immunomodulation. The existing literature indicates the role of fine structural details of AX on its potential as polysaccharides that can impact the gut associated microbial growth and immune system.

RAGE is a multi-ligand receptor involved in various human diseases including diabetes, cancer or Alzheimer's disease. Engagement of RAGE by its ligands triggers activation of key cellular signalling pathways such as the MAP kinase and NF-kappaB pathways. Whereas the main isoform of RAGE is a transmembrane receptor with both extra- and intracellular domains, a secreted soluble isoform (sRAGE), corresponding to the extracellular part only, has the ability to block RAGE signalling and suppress cellular activation. Administration of sRAGE to animal models of cancer or multiple sclerosis blocked successfully tumour growth and the course of the autoimmune disease. These findings demonstrate that sRAGE may have a potential as therapeutic. We present here a fast and simple purification protocol of sRAGE from the yeast Pichia pastoris. The identity of the protein was confirmed by mass spectrometry and Western blot. The protein was N-glycosylated and 95-98% pure as judged by SDS-PAGE.

Recent studies have suggested that the receptor for advanced glycation end products (RAGE) participates in melanoma progression by promoting tumor growth. However, the mechanisms of RAGE activation in melanoma tumors are not clearly understood. To get deeper insights into these mechanisms, we transfected a melanoma cell line, which was established from a human melanoma primary tumor, with RAGE, and studied the effect of RAGE overexpression on cell proliferation and migration in vitro. We observed that overexpression of RAGE in these cells not only resulted in significantly increased migration rates compared to control cells, but also in decreased proliferation rates (Meghnani et al., 2014). In the present study, we compared the growth of xenograft tumors established from RAGE overexpressing WM115 cells, to that of control cells. We observed that when implanted in mice, RAGE overexpressing cells generated tumors faster than control cells. Analysis of protein tumor extracts showed increased levels of the RAGE ligands S100B, S100A2, S100A4, S100A6 and S100A10 in RAGE overexpressing tumors compared to control tumors. We show that the tumor growth was significantly reduced when the mice were treated with anti-RAGE antibodies, suggesting that RAGE, and probably several S100 proteins, were involved in tumor growth. We further demonstrate that the anti-RAGE antibody treatment significantly enhanced the efficacy of the alkylating drug dacarbazine in reducing the growth rate of RAGE overexpressing tumors.

The interaction of serine/threonine-phosphorylated calmodulin with synthetic peptides corresponding to the calmodulin-binding domains of six enzymes has been studied by fluorescence spectroscopy. For five peptides, the dissociation constant of the calmodulin-peptide complex (Kd) increased when calmodulin was phosphorylated. An increase of more than one order of magnitude was observed with peptides derived from smooth-muscle myosin light-chain kinase and cAMP phosphodiesterase. In contrast, only a slight increase in Kd was noted with two peptides derived from the plasma membrane Ca2+-ATPase and for the peptide derived from nitric oxide synthase. No significant change in affinity was detected with the peptide derived from calcineurin. In contrast, a decrease in the dissociation constant was observed with the peptide derived from the Ca2+-calmodulin dependent kinase II. Phosphorylation also affected the peptide-calmodulin binding stoichiometry: a decrease from two to one binding sites was observed with the peptides derived from myosin light-chain kinase and phosphodiesterase.

Previous work has shown that calmodulin (CaM) is constitutively phosphorylated in rat liver, probably by casein kinase II [Quadroni, M., James, P., and Carafoli, E. (1994) J. Biol. Chem. 269, 16116-16122]. A procedure is now described for the isolation of the phosphorylated forms of calmodulin (PCaM) free from CaM, since in vitro phosphorylation experiments yield a 50:50 mixture of 3-4 times phosphorylated CaM and native CaM. The activation of six target enzymes by PCaM was tested: myosin light chain kinase, 3',5'-cyclic nucleotide phosphodiesterase, plasma membrane Ca2+-ATPase, Ca2+-CaM-dependent protein phosphatase 2B (calcineurin), neuronal nitric oxide synthase, and CaM-kinase II. In general, the phosphorylation of CaM caused a decrease in enzyme binding affinity, increasing the Kact by 2-4-fold for MLCK, PDE, PM Ca2+-ATPase, and calcineurin. The Vmax at saturating concentrations of PCaM was less affected, with the exception of CaM-kinase II, which was only minimally activated by PCaM and NOS whose Vmax was increased 2.6 times by PCaM with respect to CaM. Phosphorylation of calmodulin had very little effect on the binding of calcium to the enzyme despite the fact that Ser 101 which is phosphorylated is located in the third calcium binding loop. CD measurements performed on CaM and PCaM indicated that phosphorylation causes a marked decrease in the alpha-helical content of the protein. Phosphorylated CaM is very prone to dephosphorylation and was thus tested as a substrate for several phosphatases. It was unaffected by calcineurin (PP2B), but was a reasonable substrate for the pleiotropic phosphatases PP1gamma and PP2A.

Surface plasmon resonance (SPR) is a label-free biophysical method that allows to measure the binding parameters (ka, kd, K(D)) of the interaction between two molecules. In this method, one protein/molecule (ligand) is immobilized on the surface of a sensor chip, while the other molecule (analyte) is in solution. We describe here the use of SPR to measure the binding parameters of the interaction between S100 proteins and isolated domains of the receptor for advanced glycation endproducts (RAGE). In particular, we present the protocols that allow to measure the binding of S100B to RAGE V domain, and the binding of S100A1 and S100A6 to RAGE V-C1-C2 domain fused to a Glutathione S-Transferase (GST) moiety (GST-RAGE).

Recent studies suggest that the Receptor for Advanced Glycation End Products (RAGE) and its ligands (S100P or HMGB1) are important contributors to the progression of pancreatic cancer. Being a cell surface receptor, RAGE possesses a large extracellular domain that binds its activating ligands. We reasoned that monoclonal antibodies that block the interaction between RAGE and its ligands could impact the progression of pancreatic cancer. We have generated a panel of antibodies recognizing different domains of the receptor and are currently testing their inhibitory effects, in pancreatic cancer cells and in small animal models. Citation Format: Priyanka Swami, Venkata Indurthi, Stefan W. Vetter, Estelle Leclerc.{Authors}. Targeting RAGE in pancreatic cancer using monoclonal antibodies. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr A37.

Surface plasmon resonance (SPR) is a label-free biophysical method that allows to measure the binding parameters (ka, kd, K(D)) of the interaction between two molecules. In this method, one protein/molecule (ligand) is immobilized on the surface of a sensor chip, while the other molecule (analyte) is in solution. We describe here the use of SPR to measure the binding parameters of the interaction between S100 proteins and isolated domains of the receptor for advanced glycation endproducts (RAGE). In particular, we present the protocols that allow to measure the binding of S100B to RAGE V domain, and the binding of S100A1 and S100A6 to RAGE V-C1-C2 domain fused to a Glutathione S-Transferase (GST) moiety (GST-RAGE).

The incidence of melanoma continues to rise worldwide and increases annually by 4% to 6% in the United States (Darrell and Rigel 2010). Once metastatic, invasive melanoma offers poor prognosis to patients (Bhatia, Tykodi and Thompson, 2009). The classic prognostic factors in melanoma include primary tumor thickness, patient gender, primary melanoma ulceration, mitotic activity and the presence of tumor infiltrating lymphocytes (Spatz et al. 2010). Besides these established prognostic markers, the S100 protein family member S100B has emerged in recent years as a new prognostic marker and is now incorporated into the American Joint Committee on Cancer (AJCC) melanoma staging system for stage IV melanoma patients (Balch et al. 2009; Chun et al. 2008; Gogas et al. 2009). High S100B serum concentration correlates with poor survival rate (Hauschild et al. 1999). Current studies are also analyzing the prognostic value of S100B in earlier melanoma stages (IIB-III) (Bouwhuis et al. 2010). The role of S100B in the progression of melanoma is not clearly understood. For instance, although it is established that S100B is released from melanoma tumor cells, its role in tumor development, invasion and metastasis is currently under investigation. This chapter will discuss the role of S100B and other members of the S100 protein family in the biology of melanoma. We will focus on the relation between the S100 proteins and their common receptor, the receptor for advanced glycation endproducts (RAGE), in the context of melanoma.

The Receptor for Advanced Glycation Endproducts (RAGE) is a multiligand receptor involved in a large number of human disorders. Identified first as the receptor for the Advanced Glycation Endproducts (AGEs), RAGE has emerged in recent years as a major receptor for many members of the S100 calcium and zinc binding protein family. The interaction with and the signaling triggered by several S100 proteins such as S100B and S100A12 have been studied in details and have shown concentration and cell type dependent signaling cascades. The S100 protein family consists of more than 20 members which present high amino-acid sequence and structural similarities. These small EF-hand calcium binding proteins interact with a large number of protein targets and are almost all been shown to be involved in cancer. In this review we discuss the recent knowledge about the role of S100 proteins and RAGE in human disorders.

Scope: Advanced glycation endproducts (AGEs) are suspected to stimulate inflammatory signaling pathways in target tissues via activation of the receptor for AGEs. Endotoxins are generally recognized as potential contamination of AGE preparations and stimulate biological actions that are very similar as or identical to those induced by AGEs. Methods and results: In our study, we used glycolaldehyde-modified β-lactoglobulin preparations as model AGEs and employed two methods to remove endotoxin using either affinity columns or extraction with Triton X-114 (TX-114). Affinity column-purified AGEs retained their ability to stimulate inflammatory signaling as measured by mRNA expression of inflammatory cytokines in the human lung epithelial cell line Beas2b. However, glycolaldehyde-modified AGEs purified by extraction with TX-114 did not show any stimulation of mRNA expression of inflammatory cytokines. The presence of a cell stimulating endotoxin-like activity was demonstrated in the detergent phase after extraction with TX-114, thus indicating that not AGEs but a lipophilic contamination was responsible for the stimulation of inflammatory signaling. Conclusion: Our results demonstrate that glycolaldehyde-modified AGEs are unable to induce inflammatory signaling in receptor for AGE-expressing cells. The observed cell-activating activity can be ascribed to an endotoxin-like lipophilic contamination present in AGE preparations and affinity column purification was insufficient to remove this contamination.

Increasing evidence suggests that the small EF-hand calcium-binding protein S100B plays an important role in Alzheimer's disease. Among other evidences are the increased levels of both S100B and its receptor, the Receptor for Advanced Glycation Endproducts (RAGEs) in the AD diseased brain. The regulation of RAGE signaling by S100B is complex and probably involves other ligands including the amyloid beta peptide (A), the Advanced Glycation Endproducts (AGEs), or transtheyretin. In this paper we discuss the current literature regarding the role of S100B/RAGE activation in Alzheimer's disease.

The Receptor for Advanced Glycation Endproducts (RAGE) has been suggested to play an important role in melanoma. Animal studies with anti-RAGE antibodies have shown that RAGE blockade leads to reduced melanoma tumor growth and metastasis formation. RAGE is a multiligand receptor and among its ligands are the Ca-binding S100 proteins. Certain S100 proteins are differentially expressed in melanoma. For example, S100B is currently used as a reliable prognostic biomarker in patients with malignant melanoma. We have surveyed 40 human melanoma tumor samples for the transcription of RAGE and five of its known S100 protein ligands. Compared to normal skin tissue, we found highly significant (p0.0001) over-expression of S100B and underexpression of S100A2, whereas no significant difference in transcription of S100A6 and S100A10 was observed. RAGE showed slightly increased transcription in stage IV. Between individual tumor samples tremendous differences in transcription of the S100 proteins were observed, whereas RAGE expression showed relatively little variance. We also analyzed three well-characterized melanoma cell lines for S100 and RAGE expression. The S100 protein transcription profile showed clear differences between cultured melanoma cells and melanoma tumor tissue. Detailed profiling of S100 and RAGE transcription in melanoma tumors in combination with imunohisto-chemical and clinical data may lead to improved molecular diagnostic of melanoma and subsequently may facilitate improved treatment in the future.

Advanced glycation endproducts (AGEs) containing carboxymethyllysine (CML) modifications are generally thought to be ligands of the receptor for AGEs, RAGEs. It has been argued that this results in the activation of pro-inflammatory pathways and diseases. However, it has not been shown conclusively that a CML-modified protein can interact directly with RAGE. Here, we have analyzed whether beta-lactoglobulin (bLG) or human serum albumin (HSA) modified chemically to contain only CML (10-40% lysine modification) can (i) interact with RAGE in vitro and (ii) interact with and activate RAGE in lung epithelial cells. Our results show that CML-modified bLG or HSA are unable to bind to RAGE in a cell-free assay system (Biacore). Furthermore, they are unable to activate pro-inflammatory signaling in the cellular system. Thus, CML probably does not form the necessary structure(s) to interact with RAGE and activate an inflammatory signaling cascade in RAGE-expressing cells.

S100 proteins are EF-hand calcium-binding proteins with various intracellular functions including cell proliferation, differentiation, migration, and apoptosis. Some S100 proteins are also secreted and exert extracellular paracrine and autocrine functions. Experimental results suggest that the receptor for advanced glycation end products (RAGE) plays important roles in mediating S100 protein-induced cellular signaling. Here we compared the interaction of two S100 proteins, S100B and S100A6, with RAGE by in vitro assay and in culture of human SH-SY5Y neuroblastoma cells. Our in vitro binding data showed that S100B and S100A6, although structurally very similar, interact with different RAGE extracellular domains. Our cell assay data demonstrated that S100B and S100A6 differentially modulate cell survival. At micromolar concentration, S100B increased cellular proliferation, whereas at the same concentration, S100A6 triggered apoptosis. Although both S100 proteins induced the formation of reactive oxygen species, S100B recruited phosphatidylinositol 3-kinase/AKT and NF-kappaB, whereas S100A6 activated JNK. More importantly, we showed that S100B and S100A6 modulate cell survival in a RAGE-dependent manner; S100B specifically interacted with the RAGE V and C(1) domains and S100A6 specifically interacted with the C(1) and C(2) RAGE domains. Altogether these results highlight the complexity of S100/RAGE cellular signaling.

Nervous system development and plasticity require regulation of cell proliferation, survival, neurite outgrowth and synapse formation by specific extracellular factors. The EF-hand protein S100B is highly expressed in human brain. In the extracellular space, it promotes neurite extension and neuron survival via the receptor RAGE (receptor for advanced glycation end products). The X-ray structure of human Ca(2+)-loaded S100B was determined at 1.9 A resolution. The structure revealed an octameric architecture of four homodimeric units arranged as two tetramers in a tight array. The presence of multimeric forms in human brain extracts was confirmed by size-exclusion experiments. Recombinant tetrameric, hexameric and octameric S100B were purified from Escherichia coli and characterised. Binding studies show that tetrameric S100B binds RAGE with higher affinity than dimeric S100B. Analytical ultracentrifugation studies imply that S100B tetramer binds two RAGE molecules via the V-domain. In line with these experiments, S100B tetramer caused stronger activation of cell growth than S100B dimer and promoted cell survival. The structural and the binding data suggest that tetrameric S100B triggers RAGE activation by receptor dimerisation.