Common interactions between S100A4 and S100A9 defined by a novel chemical probe

S100A4 a classical DAMP as a therapeutic target in fibrosis

Fibrosis regardless of aetiology is characterised by persistently activated myofibroblasts that are contractile and secrete excessive amounts of extracellular matrix molecules that leads to loss of organ function. Damage-Associated Molecular Patterns (DAMPs) are endogenous host-derived molecules that are released from cells dying or under stress that can be triggered by a variety of insults, either chemical or physical, leading to an inflammatory response. Among these DAMPs is S100A4, part of the S100 family of calcium binding proteins that participate in a variety of cellular processes. S100A4 was first described in context of cancer as a pro-metastatic factor. It is now appreciated that aside from its role in cancer promotion, S100A4 is intimately involved in tissue fibrosis. The extracellular form of S100A4 exerts its effects through multiple receptors including Toll-Like Receptor 4 and RAGE to evoke signalling cascades involving downstream mediators facilitating extracellular matrix deposition and myofibroblast generation and can play a role in persistent activation of myofibroblasts. S100A4 may be best understood as an amplifier of inflammatory and fibrotic processes. S100A4 appears critical in systemic sclerosis pathogenesis and blocking the extracellular form of S100A4 in vivo in various animal models of disease mitigates fibrosis and may even reverse established disease. This review appraises S100A4's position as a DAMP and its role in fibrotic conditions and highlight therapeutically targeting this protein to halt fibrosis, suggesting that it is a tractable target.

The functions and regulatory pathways of S100A8/A9 and its receptors in cancers

Inflammation primarily influences the initiation, progression, and deterioration of many human diseases, and immune cells are the principal forces that modulate the balance of inflammation by generating cytokines and chemokines to maintain physiological homeostasis or accelerate disease development. S100A8/A9, a heterodimer protein mainly generated by neutrophils, triggers many signal transduction pathways to mediate microtubule constitution and pathogen defense, as well as intricate procedures of cancer growth, metastasis, drug resistance, and prognosis. Its paired receptors, such as receptor for advanced glycation ends (RAGEs) and toll-like receptor 4 (TLR4), also have roles and effects within tumor cells, mainly involved with mitogen-activated protein kinases (MAPKs), NF-κB, phosphoinositide 3-kinase (PI3K)/Akt, mammalian target of rapamycin (mTOR) and protein kinase C (PKC) activation. In the clinical setting, S100A8/A9 and its receptors can be used complementarily as efficient biomarkers for cancer diagnosis and treatment. This review comprehensively summarizes the biological functions of S100A8/A9 and its various receptors in tumor cells, in order to provide new insights and strategies targeting S100A8/A9 to promote novel diagnostic and therapeutic methods in cancers.

Neutralization of S100A4 induces stabilization of atherosclerotic plaques: role of smooth muscle cells

AIMS

During atherosclerosis, smooth muscle cells (SMCs) accumulate in the intima where they switch from a contractile to a synthetic phenotype. From porcine coronary artery, we isolated spindle-shaped (S) SMCs exhibiting features of the contractile phenotype and rhomboid (R) SMCs typical of the synthetic phenotype. S100A4 was identified as a marker of R-SMCs in vitro and intimal SMCs, in pig and man. S100A4 exhibits intra- and extracellular functions. In this study, we investigated the role of extracellular S100A4 in SMC phenotypic transition.

METHODS AND RESULTS

S-SMCs were treated with oligomeric recombinant S100A4 (oS100A4), which induced nuclear factor (NF)-κB activation. Treatment of S-SMCs with oS100A4 in combination with platelet-derived growth factor (PDGF)-BB induced a complete SMC transition towards a pro-inflammatory R-phenotype associated with NF-κB activation, through toll-like receptor-4. RNA sequencing of cells treated with oS100A4/PDGF-BB revealed a strong up-regulation of pro-inflammatory genes and enrichment of transcription factor binding sites essential for SMC phenotypic transition. In a mouse model of established atherosclerosis, neutralization of extracellular S100A4 decreased area of atherosclerotic lesions, necrotic core, and CD68 expression and increased α-smooth muscle actin and smooth muscle myosin heavy chain expression.

CONCLUSION

We suggest that the neutralization of extracellular S100A4 promotes the stabilization of atherosclerotic plaques. Extracellular S100A4 could be a new target to influence the evolution of atherosclerotic plaques.

S100A4 exerts robust mucosal adjuvant activity for co-administered antigens in mice

The lack of clinically applicable mucosal adjuvants is a major hurdle in designing effective mucosal vaccines. We hereby report that the calcium-binding protein S100A4, which regulates a wide range of biological functions, is a potent mucosal adjuvant in mice for co-administered antigens, including the SARS-CoV-2 spike protein, with comparable or even superior efficacy as cholera toxin but without causing any adverse reactions. Intranasal immunization with recombinant S100A4 elicited antigen-specific antibody and pulmonary cytotoxic T cell responses, and these responses were remarkably sustained for longer than 6 months. As a self-protein, S100A4 did not stimulate antibody responses against itself, a quality desired of adjuvants. S100A4 prolonged nasal residence of intranasally delivered antigens and promoted migration of antigen-presenting cells. S100A4-pulsed dendritic cells potently activated cognate T cells. Furthermore, S100A4 induced strong germinal center responses revealed by both microscopy and mass spectrometry, a novel label-free technique for measuring germinal center activity. Importantly, S100A4 did not induce olfactory bulb inflammation after nasal delivery, which is often a safety concern for nasal vaccination. In conclusion, S100A4 may be a promising adjuvant in formulating mucosal vaccines, including vaccines against pathogens that infect via the respiratory tract, such as SARS-CoV-2.

S100A4 promotes the progression of lipopolysaccharide-induced acute epididymitis in mice†

S100A4 has been suggested to be a critical regulator of tumor metastasis and is implicated in the progression of inflammation. The aim of this study is to investigate the expression and possible role of S100A4 in epididymitis. Using a mouse model of epididymitis induced by the injection of lipopolysaccharide (LPS) in the deferent duct, we found that LPS administration induced an upregulation of S100a4 transcription (P < 0.05) and a recruitment of S100A4 positive cells in the epididymal interstitium of wild type (WT) mice. Co-immunofluorescence showed that S100A4 was mainly expressed by granulocytes, CD4 lymphocytes, and macrophages. Deficiency of S100A4 reduced epididymal pathological reaction and the mRNA levels of the pro-inflammatory cytokines IL-1β and TNF-α (P < 0.01), suggesting that S100A4 promotes the progression of epididymitis. Furthermore, S100A4 deficiency alleviated the decline of sperm motility and rectified the abnormal expression of sperm membrane protein AMAD3, which suggested that in the progression of epididymitis, S100A4 aggravates the damage to sperm vitality. In addition, both Ki-67 marked cell proliferation and transferase-mediated dUTP-biotin nick end labeling detected cell apoptosis were reduced in S100a4-/- mice compared with WT mice after LPS treatment, indicating that S100A4 promotes both cell proliferation and cell apoptosis in epididymitis. Overall, these results demonstrate that S100A4 promotes the progression of LPS-induced epididymitis and facilitates a decline in sperm vitality, and its function may be related to the process of cell proliferation and apoptosis during inflammation.

S100A4 Is Critical for a Mouse Model of Allergic Asthma by Impacting Mast Cell Activation

Background

The calcium-binding protein S100A4 demonstrates important regulatory roles in many biological processes including tumorigenesis and inflammatory disorders such as allergy. However, the specific mechanism of the contribution of S100A4 to allergic diseases awaits further clarification.

Objective

To address the effect of S100A4 on the regulation of mast cell activation and its impact on allergy.

Methods

Bone marrow-derived cultured mast cells (BMMCs) were derived from wild-type (WT) or S100A4-/- mice for in vitro investigation. WT and S100A4-/- mice were induced to develop a passive cutaneous anaphylaxis (PCA) model, a passive systemic anaphylaxis (PSA) model, and an ovalbumin (OVA)-mediated mouse asthma model.

Results

Following OVA/alum-based sensitization and provocation, S100A4-/- mice demonstrated overall suppressed levels of serum anti-OVA IgE and IgG antibodies and proinflammatory cytokines in serum, bronchoalveolar lavage fluid (BALF), and lung exudates. S100A4-/- mice exhibited less severe asthma signs which included inflammatory cell infiltration in the lung tissue and BALF, and suppressed mast cell recruitment in the lungs. Reduced levels of antigen reencounter-induced splenocyte proliferation in vitro were recorded in splenocytes from OVA-sensitized and challenged mice that lacked S100A4-/-. Furthermore, deficiency in the S100A4 gene could dampen mast cell activation both in vitro and in vivo, evidenced by reduced β-hexosaminidase release and compromised PCA and PSA reaction. We also provided evidence supporting the expression of S100A4 by mast cells.

Conclusion

S100A4 is required for mast cell functional activation, and S100A4 may participate in the regulation of allergic responses at least partly through regulating the activation of mast cells.

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.

Is the impact of high reward sensitivity and poor cognitive control on adolescent risk-taking more visible in rewarding conditions?

Adolescents are expected to take more risks than adults. The presented study was designed to determine whether adolescent risk-taking results from high reward sensitivity and poor cognitive control. In particular, we aimed to examine whether the impact of these variables is more visible in rewarding than non-rewarding conditions. Ninety adolescents (aged 13–16) and 95 young adults (aged 20–28) took part in the study. We used a driving task in rewarded and non-rewarded conditions to measure risk-taking. We also used tasks measuring reward sensitivity, cognitive control and impulsivity. Additionally we used self-report measures of reward sensitivity, self-control and everyday risk-taking to see whether the effects observed for self-reports mimic the effects observed for behavioral tasks. We found that the higher the reward sensitivity, the more adolescents (but not adults) risk in the rewarded condition of a driving task. We found no impact of cognitive control or impulsivity on risk-taking, regardless of age and condition. At the self-report level, we found that the higher the reward sensitivity and the poorer the self-control, the more both adolescents and adults displayed everyday risk-taking behavior.

The S100 calcium-binding protein A4 level is elevated in the lungs of patients with idiopathic pulmonary fibrosis

BACKGROUND

Fibroblast dysfunction is the main pathogenic mechanism of idiopathic pulmonary fibrosis (IPF). S100 calcium-binding protein A4 (S100A4) plays critical roles in the proliferation of fibroblasts and in the development of pulmonary, hepatic, and renal fibrosis. However, the clinical implications of S100A4 in IPF have not been evaluated.

METHODS AND MATERIALS

The S100A4 mRNA and protein levels were measured by real-time PCR and immunoblotting in fibroblasts from IPF patients and controls. The S100A4 level was measured by enzyme-linked immunosorbent assay in bronchoalveolar lavage fluid (BALF) from the normal controls (NCs; n = 33) and from patients with IPF (n = 87), non-specific interstitial pneumonia (NSIP; n = 22), hypersensitivity pneumonitis (HP; n = 19), and sarcoidosis (n = 9). S100A4 localization was evaluated by immunofluorescence staining.

RESULTS

The S100A4 mRNA and protein levels were significantly higher in fibroblasts from IPF patients (n = 14) than in those from controls (n = 10, p < 0.001). The S100A4 protein level in BALF was significantly higher in the IPF (89.25 [49.92-203.02 pg/mL]), NSIP (74.53 [41.88-131.45 pg/mL]), HP (222.36 [104.92-436.92 pg/mL]) and sarcoidosis (101.62 [59.36-300.62 pg/mL]) patients than in the NCs (7.57 [1.31-14.04 pg/mL], p < 0.01, respectively). Cutoff S100A4 levels of 18.85 and 28.88 pg/mL had 87.4% and 87.8% accuracy, respectively, for discriminating IPF and other lung diseases from NCs.

CONCLUSIONS

S100A4 is expressed by α-SMA-positive cells in the interstitium of the IPF patients. S100A4 may participate in the development of IPF, and its protein level may be a candidate diagnostic and therapeutic marker for IPF.

Biomarkers of tumor invasiveness in proteomics (Review)

Over the past two decades, quantitative proteomics has emerged as an important tool for deciphering the complex molecular events involved in cancers. The number of references involving studies on the cancer metastatic process has doubled since 2010, while the last 5 years have seen the development of novel technologies combining deep proteome coverage capabilities with quantitative consistency and accuracy. To highlight key findings within this huge amount of information, the present review identified a list of tumor invasive biomarkers based on both the literature and data collected on a biocollection of experimental cell lines, tumor models of increasing invasiveness and tumor samples from patients with colorectal or breast cancer. Crossing these different data sources led to 76 proteins of interest out of 1,245 mentioned in the literature. Information on these proteins can potentially be translated into clinical prospects, since they represent potential targets for the development and evaluation of innovative therapies, alone or in combination. Herein, a systematical review of the biology of each of these proteins, including their specific subcellular/extracellular or multiple localizations is presented. Finally, as an important advantage of quantitative proteomics is the ability to provide data on all these molecules simultaneously in cell pellets, body fluids or paraffin‑embedded sections of tumors/invaded tissues, the significance of some of their interconnections is discussed.

S100A4 is a Biomarker of Tumorigenesis, EMT, Invasion, and Colonization of Host Organs in Experimental Malignant Mesothelioma

Recent findings suggest that S100A4, a protein involved in communication between stromal cells and cancer cells, could be more involved than previously expected in cancer invasiveness. To investigate its cumulative value in the multistep process of the pathogenesis of malignant mesothelioma (MM), SWATH-MS (sequential window acquisition of all theoretical fragmentation spectra), an advanced and robust technique of quantitative proteomics, was used to analyze a collection of 26 preneoplastic and neoplastic rat mesothelial cell lines and models of MM with increasing invasiveness. Secondly, proteomic and histological analyses were conducted on formalin-fixed paraffin-embedded sections of liver metastases vs. primary tumor, and spleen from tumor-bearing rats vs. controls in the most invasive MM model. We found that S100A4, along with 12 other biomarkers, differentiated neoplastic from preneoplastic mesothelial cell lines, and invasive vs. non-invasive tumor cells in vitro, and MM tumors in vivo. Additionally, S100A4 was the only protein differentiating preneoplastic mesothelial cell lines with sarcomatoid vs. epithelioid morphology in relation to EMT (epithelial-to-mesenchymal transition). Finally, S100A4 was the most significantly increased biomarker in liver metastases vs. primary tumor, and in the spleen colonized by MM cells. Overall, we showed that S100A4 was the only protein that showed increased abundance in all situations, highlighting its crucial role in all stages of MM pathogenesis.

Cell non-autonomous functions of S100a4 drive fibrotic tendon healing

Identification of pro-regenerative approaches to improve tendon healing is critically important as the fibrotic healing response impairs physical function. In the present study we tested the hypothesis that S100a4 haploinsufficiency or inhibition of S100a4 signaling improves tendon function following acute injury and surgical repair in a murine model. We demonstrate that S100a4 drives fibrotic tendon healing primarily through a cell non-autonomous process, with S100a4 haploinsufficiency promoting regenerative tendon healing. Moreover, inhibition of S100a4 signaling via antagonism of its putative receptor, RAGE, also decreases scar formation. Mechanistically, S100a4 haploinsufficiency decreases myofibroblast and macrophage content at the site of injury, with both cell populations being key drivers of fibrotic progression. Moreover, S100a4-lineage cells become α-SMA+ myofibroblasts, via loss of S100a4 expression. Using a combination of genetic mouse models, small molecule inhibitors and in vitro studies we have defined S100a4 as a novel, promising therapeutic candidate to improve tendon function after acute injury.

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.

S100A4+ Macrophages Are Necessary for Pulmonary Fibrosis by Activating Lung Fibroblasts

S100A4, a calcium-binding protein, can promote pulmonary fibrosis via fibroblast activation. Due partly to its various cellular origins, the exact role of S100A4 in the development of lung fibrosis remains elusive. Here, we show that in the bronchoalveolar lavage fluid, numbers of S100A4⁺ macrophages correlated well with S100A4 protein levels and occurrence of idiopathic pulmonary fibrosis (IPF) in patients. A mouse model of bleomycin-induced pulmonary fibrosis demonstrated S100A4⁺ macrophages as main source for extracellular S100A4 in the inflammatory phase. In vitro studies revealed that extracellular S100A4 could activate both mouse and human lung fibroblasts by upregulation of α-SMA and type I collagen, during which sphingosine-1-phosphate (S1P) increased. Inhibiting the S1P receptor subtypes S1P₁/S1P₃ abrogated fibroblast activation. Accordingly, absence or neutralization of S100A4 significantly attenuated bleomycin-induced lung fibrosis in vivo. Importantly, adoptive transfer of S100A4⁺ but not of S100A4⁻ macrophages installed experimental lung injury in S100A4^−/− mice that were otherwise not sensitive to fibrosis induction. Taken together, S100A4 released by macrophages promotes pulmonary fibrosis through activation of lung fibroblasts which is associated with S1P. This suggests that extracellular S100A4 or S100A4⁺ macrophages within the lung as promising targets for early clinical diagnosis or therapy of IPF.

Coevolution of the Toll-Like Receptor 4 Complex with Calgranulins and Lipopolysaccharide

Toll-like receptor 4 (TLR4) induces inflammation in response to both pathogen- and host-derived molecules. Lipopolysaccharide (LPS) recognition by TLR4 has been shown to occur across the amniotes, but endogenous signaling through TLR4 has not been validated outside of placental mammals. To determine whether endogenous danger signaling is also shared across amniotes, we studied the evolution of TLR4-activation by the calgranulin proteins (S100A8, S100A9, and S100A12), a clade of host molecules that potently activate TLR4 in placental mammals. We performed phylogenetic and syntenic analysis and found MRP-126—a gene in birds and reptiles—is likely orthologous to the mammalian calgranulins. We then used an ex vivo TLR4 activation assay to establish that calgranulin pro-inflammatory activity is not specific to placental mammals, but is also exhibited by representative marsupial and sauropsid species. This activity is strongly dependent on the cofactors CD14 and MD-2 for all species studied, suggesting a conserved mode of activation across the amniotes. Ortholog complementation experiments between the calgranulins, TLR4, CD14, and MD-2 revealed extensive lineage specific-coevolution and multi-way interactions between components that are necessary for the activation of NF-κB signaling by calgranulins and LPS. Our work demonstrates that calgranulin activation of TLR4 evolved at least ~320 million years ago and has been conserved in the amniote innate immune system.

Regulation of Receptor for Advanced Glycation End Products (RAGE) Ectodomain Shedding and Its Role in Cell Function

The receptor for advanced glycation end products (RAGE) is a multiligand transmembrane receptor that can undergo proteolysis at the cell surface to release a soluble ectodomain. Here we observed that ectodomain shedding of RAGE is critical for its role in regulating signaling and cellular function. Ectodomain shedding of both human and mouse RAGE was dependent on ADAM10 activity and induced with chemical activators of shedding (ionomycin, phorbol 12-myristate 13-acetate, and 4-aminophenylmercuric acetate) and endogenous stimuli (serum and RAGE ligands). Ectopic expression of the splice variant of RAGE (RAGE splice variant 4), which is resistant to ectodomain shedding, inhibited RAGE ligand dependent cell signaling, actin cytoskeleton reorganization, cell spreading, and cell migration. We found that blockade of RAGE ligand signaling with soluble RAGE or inhibitors of MAPK or PI3K blocked RAGE-dependent cell migration but did not affect RAGE splice variant 4 cell migration. We finally demonstrated that RAGE function is dependent on secretase activity as ADAM10 and γ-secretase inhibitors blocked RAGE ligand-mediated cell migration. Together, our data suggest that proteolysis of RAGE is critical to mediate signaling and cell function and may therefore emerge as a novel therapeutic target for RAGE-dependent disease states.

Involvement of fibroblast-specific protein 1 (S100A4) and matrix metalloproteinase-13 (MMP-13) in CCl4-induced reversible liver fibrosis

INTRODUCTION

The intense basic research on the molecular and cellular mechanisms of liver fibrosis regression intends to translate these findings into new therapies targeting such pathways in human liver disease. Fibrosis regression is rapidly initiated in mouse models of fibrosis within days after termination of the cause, so in this study, we investigated the expression of S100A4 and MMP-13 during liver fibrogenesis and remodeling.

METHODS

Thirty rats were divided into three groups: control group, fibrotic group, and fibrotic resolution group (10 each). The rats were sacrificed 48h and 96h after cessation of CCL-4, respectively. Liver tissue levels of S100A4 mRNA and S100A4 protein, MMP-13 mRNA and serum levels of serum TGF-β1, ALT and AST were determined.

RESULTS

Expression of S100A4 was increased during fibrotic stage and declined during resolution which was in correlation with the pro-fibrotic marker TGF-β1 with concordance about 90%, while MMP-13 expression increased in both stages reaching to 40 fold during resolution.

CONCLUSION

These findings suggested that S100A4 level in the liver tissue was related positively with liver fibrosis making it a good marker for liver fibrogenesis and also a good target for novel antifibrotic strategies.

S100A9 expressed in ER(-)PgR(-) breast cancers induces inflammatory cytokines and is associated with an impaired overall survival

Background:

Breast cancer is the most common cancer form among women today. Depending on hormone receptor status, breast cancers are divided into different subtypes with vastly varying prognosis. S100A9 is a calcium-binding protein that is associated with inflammation and expressed not only in myeloid cells but also in some tumours. The role for S100A9 in the malignant cells is not well characterised; however, previous studies have shown that the protein could have important immune-modulating properties.

Methods:

Using a human breast cancer cohort consisting of 144 tumour samples and in vitro analysis of human breast cancer cell lines, we investigated the expression and function of S100A9 in human breast cancer.

Results:

We show that S100A9 expression in breast cancer correlated with the ER⁻PgR⁻ breast tumour subtype (P<0.001) and with Ki67 (P=0.024) and was expressed both in the malignant cells and in the tumour-infiltrating anti-inflammatory CD163⁺ myeloid cells (P<0.001). Stromal expression of S100A9 also correlated to nodal stage, tumour size and Her2 positivity. Within the ER⁻PgR⁻ subgroup, all Her2⁺ and EGFR⁺ tumours expressed S100A9 in the cytoplasm. Both cytoplasmic staining in the malignant cells as well as stromal S100A9 expression in myeloid cells correlated with a decreased overall survival in breast cancer patients. Furthermore, rS100A9 homodimers induced expression of pro-inflammatory cytokines (IL-6, IL-8 and IL-1β) in a TLR4- and EGFR-dependent manner in human breast cancer cells in vitro.

Conclusion:

We suggest that S100A9 could be viewed as a novel therapeutic target for patients with ER⁻PgR⁻ breast cancers.

Diminished levels of the soluble form of RAGE are related to poor survival in malignant melanoma

RAGE is a central driver of tumorigenesis by sustaining an inflammatory tumor microenvironment. This study links the soluble forms of RAGE (sRAGE and esRAGE) with clinical outcome of melanoma patients. Moreover, tissue expression of RAGE was analyzed using immunohistochemistry on two independent tissue microarrays (TMA) containing 35 or 257 primary melanomas, and 41 or 22 benign nevi, respectively. Serum concentrations of sRAGE and esRAGE were measured in 229 Stage III-IV patients using ELISA and plasma concentrations of sRAGE were analyzed in an independent second cohort with 173 samples of Stage I-IV patients. In this cohort, three well-described SNPs in the RAGE gene were analyzed. RAGE protein expression was highly upregulated in primary melanomas compared to benign nevi in the two TMA (p < 0.001 and p = 0.005) as well as in sun-exposed melanomas (p = 0.046). sRAGE and esRAGE were identified as prognostic markers for survival as diminished sRAGE (p = 0.034) and esRAGE (p = 0.012) serum levels correlated with poor overall survival (OS). Multivariate Cox regression analysis showed that diminished serum sRAGE was independently associated with poor survival (p = 0.009). Moreover, diminished sRAGE was strongly associated with impaired OS in the second cohort (p < 0.001). Multivariate Cox regression analysis including the investigated SNPs revealed an independent correlation of the two interacting promoter SNPs with impaired OS. In conclusion, the soluble forms of RAGE and variants in its genetic locus are prognostic markers for survival in melanoma patients with high risk for progression.

Novel inflammatory biomarkers in primary hyperparathyroidism

OBJECTIVE

Primary hyperparathyroidism (PHPT) has been associated with low-grade inflammation and increased risk of cardiovascular disease (CVD). The aim of the study was to investigate systemic levels of pro-inflammatory proteins that previously have not been examined in patients with PHPT. The selection of the pro-inflammatory biomarkers included in this study, MMP9, S100A4, S100A8/A9 and the receptors sCD14 and RAGE, was based on a previous microarray screen of mRNAs in adipose tissue from PHPT patients.

DESIGN

A prospective study was conducted on a total of 57 patients with PHPT and a control group of 20 healthy blood donors.

METHODS

PHPT patients with normalisation of serum calcium levels after parathyroidectomy were followed for 6 months. Forty-two patients participated in the longitudinal study, in which blood samples were taken at inclusion, and 1, 3 and 6 months after surgery.

RESULTS

We observed increased serum levels of MMP9 (P=0.029), S100A4 (P<0.001) and sCD14 (P=0.002) in the 57 patients with PHPT compared to the control-group. During 6 months of follow up, S100A4 (P=0.022) and sCD14 (0.002) decreased significantly, while serum levels of MMP9 increased (P=0.025).

CONCLUSIONS

The results demonstrate an increased inflammatory response in PHPT patients shown by elevated MMP9, S100A4 and sCD14 at inclusion. During the 6 months of follow-up, MMP9 increased further, possibly due to the tissue repair process after parathyroidectomy. S100A4 and sCD14 decreased after surgery demonstrating a partial reversal of the systemic inflammation.

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.

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.

S100A4 promotes liver fibrosis via activation of hepatic stellate cells

BACKGROUND & AIMS

S100A4 has been linked to the fibrosis of several organs due to its role as a fibroblast-specific marker. However, the role of S100A4 itself in the development of fibrosis has not been much investigated. Here, we determined whether S100A4 regulates liver fibrogenesis and examined its mechanism by focusing on the activation of hepatic stellate cells (HSCs).

METHODS

S100A4 deficient mice were used to determine the role of S100A4 in liver fibrogenesis. The effect of S100A4 on HSC activation was estimated by using primary mouse HSCs and the human HSC cell line LX-2. Serum levels of S100A4 in cirrhotic patients were determined by ELISA.

RESULTS

S100A4 was found to be secreted by a subpopulation of macrophages and to promote the development of liver fibrosis. It accumulated in the liver during the progression of liver fibrosis and activated HSCs in mice. In vitro studies demonstrated that S100A4 induced the overexpression of alpha-smooth muscle actin through c-Myb in HSCs. Both, the selective depletion of S100A4-expressing cells and knockdown of S100A4 in the liver by RNA interference, resulted in a reduction of liver fibrosis following injury. Importantly, increased S100A4 levels in both the liver tissue and serum correlated positively with liver fibrosis in humans.

CONCLUSIONS

S100A4 promotes liver fibrosis by activating HSCs, which may represent a potential target for anti-fibrotic therapies.

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.

Mechanisms of action of tasquinimod on the tumour microenvironment

Tasquinimod is a small molecule with pleiotropic effects on the tumour microenvironment. Tasquinimod inhibits the growth and metastasis of tumour cells in vitro and in vivo. It targets the tumour microenvironment, enhancing the host immune response and inhibiting the angiogenic response. Tasquinimod influences infiltrating myeloid cells in the tumour milieu shifting the balance towards a less immunosuppressive phenotype. Myeloid-derived suppressor cells and tumour-associated macrophages are major components of the immunosuppressive microenvironment and as a result promote tumour growth and favour angiogenesis and metastasis formation. Growing evidence indicates that tasquinimod targets these myeloid cells and modulates local tumour immunity by blocking the interaction between the multifunctional protein S100A9 and its ligands receptor of advanced glycation end products and Toll-like receptor 4. Its anti-angiogenic effects are achieved at least in part through these effects on regulatory myeloid cells and also potentially through inactivating histone deacetylase-4 and reducing expression of hypoxia-inducible factor 1-controlled genes. The aim is to comprehensively review the mode of action of tasquinimod as a novel oral anti-cancer agent. Based on its unique combination of effects, tasquinimod is a novel agent with clinical therapeutic potential in various solid tumours, both alone and as part of rational combination therapy.