Syndecan-1 is required for Wnt-1-induced mammary tumorigenesis in mice

Integrated bioinformatics analysis reveals upregulated extracellular matrix hub genes in pancreatic cancer: Implications for diagnosis, prognosis, immune infiltration, and therapeutic strategies

BACKGROUND

Pancreatic cancer (PC) stands out as one of the most formidable malignancies and exhibits an exceptionally unfavorable clinical prognosis due to the absence of well-defined diagnostic indicators and its tendency to develop resistance to therapeutic interventions. The primary objective of this present study was to identify extracellular matrix (ECM)-related hub genes (HGs) and their corresponding molecular signatures, with the intent of potentially utilizing them as biomarkers for diagnostic, prognostic, and therapeutic applications.

METHODS

Three microarray datasets were sourced from the NCBI database to acquire upregulated differentially expressed genes (DEGs), while MatrisomeDB was employed for filtering ECM-related genes. Subsequently, a protein-protein interaction (PPI) network was established using the STRING database. The created network was visually inspected through Cytoscape, and HGs were identified using the CytoHubba plugin tool. Furthermore, enrichment analysis, expression pattern analysis, clinicopathological correlation, survival analysis, immune cell infiltration analysis, and examination of chemical compounds were carried out using Enrichr, GEPIA2, ULCAN, Kaplan Meier plotter, TIMER2.0, and CTD web platforms, respectively. The diagnostic and prognostic significance of HGs was evaluated through the ROC curve analysis.

RESULTS

Ten genes associated with ECM functions were identified as HGs among 131 DEGs obtained from microarray datasets. Notably, the expression of these HGs exhibited significantly (p < 0.05) higher in PC, demonstrating a clear association with tumor advancement. Remarkably, higher expression levels of these HGs were inversely correlated with the likelihood of patient survival. Moreover, ROC curve analysis revealed that identified HGs are promising biomarkers for both diagnostic (AUC > 0.75) and prognostic (AUC > 0.64) purposes. Furthermore, we observed a positive correlation between immune cell infiltration and the expression of most HGs. Lastly, our study identified nine compounds with significant interaction profiles that could potentially act as effective chemical agents targeting the identified HGs.

CONCLUSION

Taken together, our findings suggest that COL1A1, KRT19, MMP1, COL11A1, SDC1, ITGA2, COL1A2, POSTN, FN1, and COL5A1 hold promise as innovative biomarkers for both the diagnosis and prognosis of PC, and they present as prospective targets for therapeutic interventions aimed at impeding the progression PC.

Roles of extracellular matrix in lung diseases

Extracellular matrix (ECM) is a non-cellular constituent found in all tissues and organs. Although ECM was previously recognized as a mere "molecular glue" that supports the tissue structure of organs such as the lungs, it has recently been reported that ECM has important biological activities for tissue morphogenesis, inflammation, wound healing, and tumor progression. Proteoglycans are the main constituent of ECM, with growing evidence that proteoglycans and their associated glycosaminoglycans play important roles in the pathogenesis of several diseases. However, their roles in the lungs are incompletely understood. Leukocyte migration into the lung is one of the main aspects involved in the pathogenesis of several lung diseases. Glycosaminoglycans bind to chemokines and their interaction fine-tunes leukocyte migration into the affected organs. This review focuses on the role chemokine and glycosaminoglycan interactions in neutrophil migration into the lung. Furthermore, this review presents the role of proteoglycans such as syndecan, versican, and hyaluronan in inflammatory and fibrotic lung diseases.

Metabolic reprogramming by Syntenin-1 directs RA FLS and endothelial cell-mediated inflammation and angiogenesis

A novel rheumatoid arthritis (RA) synovial fluid protein, Syntenin-1, and its receptor, Syndecan-1 (SDC-1), are colocalized on RA synovial tissue endothelial cells and fibroblast-like synoviocytes (FLS). Syntenin-1 exacerbates the inflammatory landscape of endothelial cells and RA FLS by upregulating transcription of IRF1/5/7/9, IL-1β, IL-6, and CCL2 through SDC-1 ligation and HIF1α, or mTOR activation. Mechanistically, Syntenin-1 orchestrates RA FLS and endothelial cell invasion via SDC-1 and/or mTOR signaling. In Syntenin-1 reprogrammed endothelial cells, the dynamic expression of metabolic intermediates coincides with escalated glycolysis along with unchanged oxidative factors, AMPK, PGC-1α, citrate, and inactive oxidative phosphorylation. Conversely, RA FLS rewired by Syntenin-1 displayed a modest glycolytic-ATP accompanied by a robust mitochondrial-ATP capacity. The enriched mitochondrial-ATP detected in Syntenin-1 reprogrammed RA FLS was coupled with mitochondrial fusion and fission recapitulated by escalated Mitofusin-2 and DRP1 expression. We found that VEGFR1/2 and Notch1 networks are responsible for the crosstalk between Syntenin-1 rewired endothelial cells and RA FLS, which are also represented in RA explants. Similar to RA explants, morphological and transcriptome studies authenticated the importance of VEGFR1/2, Notch1, RAPTOR, and HIF1α pathways in Syntenin-1 arthritic mice and their obstruction in SDC-1 deficient animals. Consistently, dysregulation of SDC-1, mTOR, and HIF1α negated Syntenin-1 inflammatory phenotype in RA explants, while inhibition of HIF1α impaired synovial angiogenic imprint amplified by Syntenin-1. In conclusion, since the current therapies are ineffective on Syntenin-1 and SDC-1 expression in RA synovial tissue and blood, targeting this pathway and its interconnected metabolic intermediates may provide a novel therapeutic strategy.

Endothelial cell activation and glycocalyx shedding - potential as biomarkers in patients with lupus nephritis

Lupus nephritis (LN) is a common and severe manifestation of systemic lupus erythematosus and an important cause of acute and chronic kidney injury. Early diagnosis of LN and preventing relapses are key to preserving renal reserve. However, due to the complexity and heterogeneity of the disease, clinical management remains challenging. Kidney biopsy remains the gold standard for confirming the diagnosis of LN and subsequent assessment of kidney histopathology, but it is invasive and cannot be repeated frequently. Current clinical indicators of kidney function such as proteinuria and serum creatinine level are non-specific and do not accurately reflect histopathological changes, while anti-dsDNA antibody and C3 levels reflect immunological status but not kidney injury. Identification of novel and specific biomarkers for LN is prerequisite to improve management. Renal function deterioration is associated with changes in the endothelial glycocalyx, a delicate gel-like layer located at the interface between the endothelium and bloodstream. Inflammation induces endothelial cell activation and shedding of glycocalyx constituents into the circulation. This review discusses the potential role of soluble glycocalyx components as biomarkers of active LN, especially in patients in whom conventional serological and biochemical markers do not appear helpful.

Gene network analyses of larvae under different egg-protecting behaviors provide novel insights into immune response mechanisms of Amphioctopus fangsiao

Amphioctopus fangsiao was a representative economic species in cephalopods, which was vulnerable to marine bacteria. Vibrio anguillarum was a highly infectious pathogen that have recently been found to infect A. fangsiao and inhibit its growth and development. There were significant differences in the immune response mechanisms between egg-protected and egg-unprotected larvae. To explore larval immunity under different egg-protecting behaviors, we infected A. fangsiao larvae with V. anguillarum for 24 h and analyzed the transcriptome data about egg-protected and egg-unprotected larvae infected with 0, 4, 12, and 24 h using weighted gene co-expression networks (WGCNA) and protein-protein interaction (PPI) networks. Network analyses revealed a series of immune response processes after infection, and identified six key modules and multiple immune-related hub genes. Meanwhile, we found that ZNF family, such as ZNF32, ZNF160, ZNF271, ZNF479, and ZNF493 might play significant roles in A. fangsiao immune response processes. We first creatively combined WGCNA and PPI network analysis to deeply explore the immune response mechanisms of A. fangsiao larvae with different egg-protecting behaviors. Our results provided further insights into the immunity of V. anguillarum infected invertebrates, and laid the foundation for exploring the immune differences among cephalopods with different egg protecting behaviors.

Syntenin-1-mediated arthritogenicity is advanced by reprogramming RA metabolic macrophages and Th1 cells

OBJECTIVES

Syntenin-1, a novel endogenous ligand, was discovered to be enriched in rheumatoid arthritis (RA) specimens compared with osteoarthritis synovial fluid and normal synovial tissue (ST). However, the cellular origin, immunoregulation and molecular mechanism of syntenin-1 are undescribed in RA.

METHODS

RA patient myeloid and lymphoid cells, as well as preclinical models, were used to investigate the impact of syntenin-1/syndecan-1 on the inflammatory and metabolic landscape.

RESULTS

Syntenin-1 and syndecan-1 (SDC-1) co-localise on RA ST macrophages (MΦs) and endothelial cells. Intriguingly, blood syntenin-1 and ST SDC-1 transcriptome are linked to cyclic citrullinated peptide, erythrocyte sedimentation rate, ST thickness and bone erosion. Metabolic CD14+CD86+GLUT1+MΦs reprogrammed by syntenin-1 exhibit a wide range of proinflammatory interferon transcription factors, monokines and glycolytic factors, along with reduced oxidative intermediates that are downregulated by blockade of SDC-1, glucose uptake and/or mTOR signalling. Inversely, IL-5R and PDZ1 inhibition are ineffective on RA MΦs-reprogrammed by syntenin-1. In syntenin-1-induced arthritis, F4/80+iNOS+RAPTOR+MΦs represent glycolytic RA MΦs, by amplifying the inflammatory and glycolytic networks. Those networks are abrogated in SDC-1-/- animals, while joint prorepair monokines are unaffected and the oxidative metabolites are moderately replenished. In RA cells and/or preclinical model, syntenin-1-induced arthritogenicity is dependent on mTOR-activated MΦ remodelling and its ability to cross-regulate Th1 cells via IL-12 and IL-18 induction. Moreover, RA and joint myeloid cells exposed to Syntenin-1 are primed to transform into osteoclasts via SDC-1 ligation and RANK, CTSK and NFATc1 transcriptional upregulation.

CONCLUSION

The syntenin-1/SDC-1 pathway plays a critical role in the inflammatory and metabolic landscape of RA through glycolytic MΦ and Th1 cell cross-regulation (graphical abstract).

The cytokine receptor DR3 identifies and promotes the activation of thymic NKT17 cells

Invariant natural killer T (iNKT) cells correspond to a population of thymus-generated T cells with innate-like characteristics and effector functions. Among the various iNKT subsets, NKT17 is the only subset that produces the proinflammatory cytokine IL-17. But, how NKT17 cells acquire this ability and what would selectively trigger their activation remain incompletely understood. Here, we identified the cytokine receptor DR3 being specifically expressed on thymic NKT17 cells and mostly absent on other thymic iNKT subsets. Moreover, DR3 ligation promoted the in vivo activation of thymic NKT17 cells and provided costimulatory effects upon agonistic α-GalCer stimulation. Thus, we identified a specific surface marker for thymic NKT17 cells that triggers their activation and augments their effector functions both in vivo and in vitro. These findings provide new insights for deciphering the role and function of murine NKT17 cells and for understanding the development and activation mechanisms of iNKT cells in general.

Molecular Insights in Uterine Leiomyosarcoma: A Systematic Review

Uterine fibroids (UFs) are the most common benign tumors of female genital diseases, unlike uterine leiomyosarcoma (LMS), a rare and aggressive uterine cancer. This narrative review aims to discuss the biology and diagnosis of LMS and, at the same time, their differential diagnosis, in order to distinguish the biological and molecular origins. The authors performed a Medline and PubMed search for the years 1990–2022 using a combination of keywords on the topics to highlight the many genes and proteins involved in the pathogenesis of LMS. The mutation of these genes, in addition to the altered expression and functions of their enzymes, are potentially biomarkers of uterine LMS. Thus, the use of this molecular and protein information could favor differential diagnosis and personalized therapy based on the molecular characteristics of LMS tissue, leading to timely diagnoses and potential better outcomes for patients.

Coreceptor Functions of Cell Surface Heparan Sulfate Proteoglycans

Receptor-ligand interactions play an important role in many biological processes by triggering specific cellular responses. These interactions are frequently regulated by coreceptors that facilitate, alter, or inhibit signaling. Coreceptors work in parallel with other specific and accessory molecules to coordinate receptor-ligand interactions. Cell surface heparan sulfate proteoglycans (HSPGs) function as unique coreceptors because they can bind to many ligands and receptors through their HS and core protein motifs. Cell surface HSPGs are typically expressed in abundance of the signaling receptors and, thus, are capable of mediating the initial binding of ligands to the cell surface. HSPG coreceptors do not possess kinase domains or intrinsic enzyme activities and, for the most part, binding to cell surface HSPGs does not directly stimulate intracellular signaling. Because of these features, cell surface HSPGs primarily function as coreceptors for many receptor-ligand interactions. Given that cell surface HSPGs are widely conserved, they likely serve fundamental functions to preserve basic physiological processes. Indeed, cell surface HSPGs can support specific cellular interactions with growth factors, morphogens, chemokines, extracellular matrix (ECM) components, and microbial pathogens and their secreted virulence factors. Through these interactions, HSPG coreceptors regulate cell adhesion, proliferation, migration and differentiation, and impact the onset, progression, and outcome of pathophysiological processes, such as development, tissue repair, inflammation, infection, and tumorigenesis. This review seeks to provide an overview of the various mechanisms of how cell surface HSPGs function as coreceptors.

Extracellular Matrix: Surface Proteoglycans

Cell surface proteoglycans, such as syndecans and glypicans, regulate molecular interactions that mediate cell adhesion, migration, proliferation, and differentiation. Through these activities, surface proteoglycans modulate critical biological processes of development, inflammation, infection, tissue repair, and cancer metastasis. Proteoglycans are unique glycoproteins comprised of one or several glycosaminoglycans attached covalently to core proteins. Glycosaminoglycans mediate the majority of ligand-binding functions of proteoglycans. Accumulating evidence indicates that surface proteoglycans regulate the onset, progression, and outcome of lung diseases, including lung injury, infection, fibrosis, and cancer. This article will review key features of surface proteoglycan biology in lung health and disease.

Interleukin-34 Reprograms Glycolytic and Osteoclastic Rheumatoid Arthritis Macrophages via Syndecan 1 and Macrophage Colony-Stimulating Factor Receptor

OBJECTIVE

In rheumatoid arthritis (RA), elevated serum interleukin-34 (IL-34) levels are linked with increased disease severity. IL-34 binds to 2 receptors, macrophage colony-stimulating factor receptor (M-CSFR) and syndecan 1, which are coexpressed in RA macrophages. Expression of both IL-34 and syndecan 1 is strikingly elevated in the RA synovium, yet their mechanisms of action remain undefined. This study was undertaken to investigate the mechanism of action of IL-34 in RA.

METHODS

To characterize the significance of IL-34 in immunometabolism, its mechanism of action was elucidated in joint macrophages, fibroblasts, and T effector cells using RA and preclinical models.

RESULTS

Intriguingly, syndecan 1 activated IL-34-induced M-CSFR phosphorylation and reprogrammed RA naive cells into distinctive CD14+CD86+GLUT1+ M34 macrophages that expressed elevated levels of IL-1β, CXCL8, and CCL2. In murine M34 macrophages, the inflammatory phenotype was accompanied by potentiated glycolytic activity, exhibited by transcriptional up-regulation of GLUT1, c-Myc, and hypoxia-inducible factor 1α (HIF-1α) and amplified pyruvate and l-lactate secretion. Local expression of IL-34 provoked arthritis by expanding the glycolytic F4/80-positive, inducible nitric oxide synthase (iNOS)-positive macrophage population, which in turn attracted fibroblasts and polarized Th1/Th17 cells. The cross-talk between murine M34 macrophages and Th1/Th17 cells broadened the inflammatory and metabolic phenotypes, resulting in the expansion of IL-34 pathogenicity. Consequently, IL-34-instigated joint inflammation was alleviated in RAG-/- mice compared to wild-type mice. Syndecan 1 deficiency attenuated IL-34-induced arthritis by interfering with joint glycolytic M34 macrophage and osteoclast remodeling. Similarly, inhibition of glycolysis by 2-deoxy-d-glucose reversed the joint swelling and metabolic rewiring triggered by IL-34 via HIF-1α and c-Myc induction.

CONCLUSION

IL-34 is a novel endogenous factor that remodels hypermetabolic M34 macrophages and facilitates their cross-regulation with T effector cells to advance inflammatory bone destruction in RA.

Role of HSPGs in Systemic Bacterial Infections

Heparan sulfate proteoglycans (HSPGs) are at the forefront of host-microbe interactions. Cell surface HSPGs are thought to promote infection as attachment and internalization receptors for many bacterial pathogens and as soluble inhibitors of host immunity when released from the cell surface by ectodomain shedding. However, the importance of HSPG-pathogen interactions in vivo has yet to be clearly established. Here we describe several representative methods to study the role of HSPGs in systemic bacterial infections, such as bacteremia and sepsis. The overall experimental strategy is to use mouse models to establish the physiological significance of HSPGs, to determine the identity of HSPGs that specifically promote infection, and to define key structural features of HSPGs that enhance bacterial virulence in systemic infections.

CD138 expression is a molecular signature but not a developmental requirement for RORγt+ NKT17 cells

Invariant NKT (iNKT) cells are potent immunomodulatory cells that acquire effector function during their development in the thymus. IL-17-producing iNKT cells are commonly referred to as NKT17 cells, and they are unique among iNKT cells to express the heparan sulfate proteoglycan CD138 and the transcription factor RORγt. Whether and how CD138 and RORγt contribute to NKT17 cell differentiation, and whether there is an interplay between RORγt and CD138 expression to control iNKT lineage fate, remain mostly unknown. Here, we showed that CD138 expression was only associated with and not required for the differentiation and IL-17 production of NKT17 cells. Consequently, CD138-deficient mice still generated robust numbers of IL-17-producing RORγt+ NKT17 cells. Moreover, forced expression of RORγt significantly promoted the generation of thymic NKT17 cells, but did not induce CD138 expression on non-NKT17 cells. These results indicated that NKT17 cell generation and IL-17 production were driven by RORγt, employing mechanisms that were independent of CD138. Therefore, our study effectively dissociated CD138 expression from the RORγt-driven molecular pathway of NKT17 cell differentiation.

Syndecan-3 enhances anabolic bone formation through WNT signaling

Osteoporosis is the most common age‐related metabolic bone disorder, which is characterized by low bone mass and deterioration in bone architecture, with a propensity to fragility fractures. The best treatment for osteoporosis relies on stimulation of osteoblasts to form new bone and restore bone structure, however, anabolic therapeutics are few and their use is time restricted. Here, we report that Syndecan‐3 increases new bone formation through enhancement of WNT signaling in osteoblasts. Young adult Sdc3^−/− mice have low bone volume, reduced bone formation, increased bone marrow adipose tissue, increased bone fragility, and a blunted anabolic bone formation response to mechanical loading. This premature osteoporosis‐like phenotype of Sdc3^−/− mice is due to delayed osteoblast maturation and impaired osteoblast function, with contributing increased osteoclast‐mediated bone resorption. Indeed, overexpressing Sdc3 in osteoblasts using the Col1a1 promoter rescues the low bone volume phenotype of the Sdc3^−/− mice, and also increases bone volume in WT mice. Mechanistically, SDC3 enhances canonical WNT signaling in osteoblasts through stabilization of Frizzled 1, making SDC3 an attractive target for novel bone anabolic drug development.

Heparanase modulation by Wingless/INT (Wnt)

Heparanase is an endo-beta-glucuronidase, the only enzyme in mammals capable of cleaving heparan sulfate/heparin chains from proteoglycans. The oligosaccharides generated by heparanase present extensive biological functions since such oligosaccharides interact with adhesion molecules, growth factors, angiogenic factors and cytokines, modulating cell proliferation, migration, inflammation, and carcinogenesis. However, the regulation of heparanase activity is not fully understood. It is known that heparanase is synthesized as an inactive 65 kDa isoform and that post-translation processing forms an active 50 kDa enzyme. In the present study, we are interested in investigating whether heparanase is regulated by its own substrate as observed with many other enzymes. Wild-type Chinese hamster (Cricetulus griséus) ovary cells (CHO-K1) were treated with different doses of heparin. Heparanase expression was analyzed by Real-time PCR and flow cytometry. Also, heparanase activity was measured. The heparanase activity assay was performed using a coated plate with biotinylated heparan sulfate. In the present assay, a competitive heparin inhibition scenario was set aside. Exogenous heparin trigged a cell signaling pathway that increased heparanase mRNA and protein levels. The Wnt/beta-catenin pathway, judged by TCF-driven luciferase activity, seems to be involved to enhance heparanase profile during treatment with exogenous heparin. Lithium chloride treatment, an activator of the Wnt/beta-catenin pathway, confirmed such mechanism of transduction in vivo using zebrafish embryos and in vitro using CHO-K1 cells. Taken together the results suggest that heparin modulates heparanase expression by Wnt/beta-catenin.

Serum syndecan-1, hyaluronan and thrombomodulin levels in patients with lupus nephritis

OBJECTIVES

We investigated circulating syndecan-1, HA and thrombomodulin levels in patients with biopsy-proven Class III/IV ± V LN and their clinico-pathological associations. Patients with non-renal SLE or non-lupus chronic kidney disease, and healthy subjects served as controls.

METHODS

Serum syndecan-1, HA and thrombomodulin levels were determined by ELISAs.

RESULTS

Syndecan-1, HA and thrombomodulin levels were significantly higher during active LN compared with remission (P < 0.01, for all), and correlated with the level of proteinuria, estimated glomerular filtration rate, anti-dsDNA antibodies, complement 3 and serum creatinine. Longitudinal studies showed that syndecan-1 and thrombomodulin levels increased prior to clinical renal flare by 3.6 months, while HA level increased at the time of nephritic flare, and the levels decreased in parallel with treatment response. Receiver operating characteristic curve analysis showed that syndecan-1 and thrombomodulin levels distinguished patients with active LN from healthy subjects, LN patients in remission, patients with active non-renal lupus and patients with non-lupus chronic kidney disease (receiver operating characteristic area under curve of 0.98, 0.91, 0.82 and 0.95, respectively, for syndecan-1; and area under curve of 1.00, 0.84, 0.97 and 0.79, respectively, for thrombomodulin). HA level distinguished active LN from healthy subjects, LN patients in remission and non-lupus chronic kidney disease (receiver operating characteristic area under curve of 0.82, 0.71 and 0.90, respectively) but did not distinguish between renal vs non-renal lupus. Syndecan-1 and thrombomodulin levels correlated with the severity of interstitial inflammation, while HA level correlated with chronicity grading in kidney biopsies of active LN.

CONCLUSION

Our findings suggest potential utility of serum syndecan-1, thrombomodulin and HA levels in clinical management, and their potential contribution to LN pathogenesis.

Syndecan-1 (CD138), Carcinomas and EMT

Cell surface proteoglycans are known to be important regulators of many aspects of cell behavior. The principal family of transmembrane proteoglycans is the syndecans, of which there are four in mammals. Syndecan-1 is mostly restricted to epithelia, and bears heparan sulfate chains that are capable of interacting with a large array of polypeptides, including extracellular matrix components and potent mediators of proliferation, adhesion and migration. For this reason, it has been studied extensively with respect to carcinomas and tumor progression. Frequently, but not always, syndecan-1 levels decrease as tumor grade, stage and invasiveness and dedifferentiation increase. This parallels experiments that show depletion of syndecan-1 can be accompanied by loss of cadherin-mediated adhesion. However, in some tumors, levels of syndecan-1 increase, but the characterization of its distribution is relevant. There can be loss of membrane staining, but acquisition of cytoplasmic and/or nuclear staining that is abnormal. Moreover, the appearance of syndecan-1 in the tumor stroma, either associated with its cellular component or the collagenous matrix, is nearly always a sign of poor prognosis. Given its relevance to myeloma progression, syndecan-1-directed antibody—toxin conjugates are being tested in clinical and preclinical trials, and may have future relevance to some carcinomas.

From Oncogenic Signaling Pathways to Single-Cell Sequencing of Immune Cells: Changing the Landscape of Cancer Immunotherapy

Over the past decade, there have been remarkable advances in understanding the signaling pathways involved in cancer development. It is well-established that cancer is caused by the dysregulation of cellular pathways involved in proliferation, cell cycle, apoptosis, cell metabolism, migration, cell polarity, and differentiation. Besides, growing evidence indicates that extracellular matrix signaling, cell surface proteoglycans, and angiogenesis can contribute to cancer development. Given the genetic instability and vast intra-tumoral heterogeneity revealed by the single-cell sequencing of tumoral cells, the current approaches cannot eliminate the mutating cancer cells. Besides, the polyclonal expansion of tumor-infiltrated lymphocytes in response to tumoral neoantigens cannot elicit anti-tumoral immune responses due to the immunosuppressive tumor microenvironment. Nevertheless, the data from the single-cell sequencing of immune cells can provide valuable insights regarding the expression of inhibitory immune checkpoints/related signaling factors in immune cells, which can be used to select immune checkpoint inhibitors and adjust their dosage. Indeed, the integration of the data obtained from the single-cell sequencing of immune cells with immune checkpoint inhibitors can increase the response rate of immune checkpoint inhibitors, decrease the immune-related adverse events, and facilitate tumoral cell elimination. This study aims to review key pathways involved in tumor development and shed light on single-cell sequencing. It also intends to address the shortcomings of immune checkpoint inhibitors, i.e., their varied response rates among cancer patients and increased risk of autoimmunity development, via applying the data from the single-cell sequencing of immune cells.

Syndecan-1 and stromal heparan sulfate proteoglycans: key moderators of plasma cell biology and myeloma pathogenesis

Plasma cells no longer express a B-cell antigen receptor and are hence deprived of signals crucial for survival throughout B-cell development. Instead, normal plasma cells, as well as their malignant myeloma counterparts, heavily rely on communication with the bone marrow (BM) microenvironment for survival. The plasma cell heparan sulfate proteoglycan (HSPG) syndecan-1 (CD138) and HSPGs in the BM microenvironment act as master regulators of this communication by co-opting specific growth and survival factors from the BM niche. This designates syndecan-1/HSPGs and their synthesis machinery as potential treatment targets in multiple myeloma.

Generation of extracellular morphogen gradients: the case for diffusion

Cells within developing tissues rely on morphogens to assess positional information. Passive diffusion is the most parsimonious transport model for long-range morphogen gradient formation but does not, on its own, readily explain scaling, robustness and planar transport. Here, we argue that diffusion is sufficient to ensure robust morphogen gradient formation in a variety of tissues if the interactions between morphogens and their extracellular binders are considered. A current challenge is to assess how the affinity for extracellular binders, as well as other biophysical and cell biological parameters, determines gradient dynamics and shape in a diffusion-based transport system. Technological advances in genome editing, tissue engineering, live imaging and in vivo biophysics are now facilitating measurement of these parameters, paving the way for mathematical modelling and a quantitative understanding of morphogen gradient formation and modulation.

Syndecans and Pancreatic Ductal Adenocarcinoma

Pancreatic Ductal Adenocarcinoma (PDAC) is a fatal disease with poor prognosis because patients rarely express symptoms in initial stages, which prevents early detection and diagnosis. Syndecans, a subfamily of proteoglycans, are involved in many physiological processes including cell proliferation, adhesion, and migration. Syndecans are physiologically found in many cell types and their interactions with other macromolecules enhance many pathways. In particular, extracellular matrix components, growth factors, and integrins collect the majority of syndecans associations acting as biochemical, physical, and mechanical transducers. Syndecans are transmembrane glycoproteins, but occasionally their extracellular domain can be released from the cell surface by the action of matrix metalloproteinases, converting them into soluble molecules that are capable of binding distant molecules such as extracellular matrix (ECM) components, growth factor receptors, and integrins from other cells. In this review, we explore the role of syndecans in tumorigenesis as well as their potential as therapeutic targets. Finally, this work reviews the contribution of syndecan-1 and syndecan-2 in PDAC progression and illustrates its potential to be targeted in future treatments for this devastating disease.

Syndecan receptors: pericellular regulators in development and inflammatory disease

The syndecans are the major family of transmembrane proteoglycans, usually bearing multiple heparan sulfate chains. They are present on virtually all nucleated cells of vertebrates and are also present in invertebrates, indicative of a long evolutionary history. Genetic models in both vertebrates and invertebrates have shown that syndecans link to the actin cytoskeleton and can fine-tune cell adhesion, migration, junction formation, polarity and differentiation. Although often associated as co-receptors with other classes of receptors (e.g. integrins, growth factor and morphogen receptors), syndecans can nonetheless signal to the cytoplasm in discrete ways. Syndecan expression levels are upregulated in development, tissue repair and an array of human diseases, which has led to the increased appreciation that they may be important in pathogenesis not only as diagnostic or prognostic agents, but also as potential targets. Here, their functions in development and inflammatory diseases are summarized, including their potential roles as conduits for viral pathogen entry into cells.

The heparan sulfate proteoglycan Syndecan-1 influences local bone cell communication via the RANKL/OPG axis

The heparan sulfate proteoglycan Syndecan-1, a mediator of signals between the extracellular matrix and cells involved is able to interact with OPG, one of the major regulators of osteoclastogenesis. The potential of osteoblasts to induce osteoclastogenesis is characterized by a switch of OPG (low osteoclastogenic potential) towards RANKL production (high osteoclastogenic potential). In the present study, we investigated the influence of endogenous Syndecan-1 on local bone-cell-communication via the RANKL/OPG-axis in murine osteoblasts and osteoclasts in wild type and Syndecan-1 lacking cells. Syndecan-1 expression and secretion was increased in osteoblasts with high osteoclastogenic potential. Syndecan-1 deficiency led to increased OPG release by osteoblasts that decreased the availability of RANKL. In co-cultures of Syndecan-1 deficient osteoblasts with osteoclast these increased OPG in supernatant caused decreased development of osteoclasts. Syndecan-1 and RANKL level were increased in serum of aged WT mice, whereas Syndecan-1 deficient mice showed high serum OPG concentration. However, bone structure of Syndecan-1 deficient mice was not different compared to wild type. In conclusion, Syndecan-1 could be regarded as a new modulator of bone-cell-communication via RANKL/OPG axis. This might be of high impact during bone regeneration or bone diseases like cancer where Syndecan-1 expression is known to be even more prevalent.

Wnt signaling in breast cancer: biological mechanisms, challenges and opportunities

Wnt signaling is a highly conserved signaling pathway that plays a critical role in controlling embryonic and organ development, as well as cancer progression. Genome-wide sequencing and gene expression profile analyses have demonstrated that Wnt signaling is involved mainly in the processes of breast cancer proliferation and metastasis. The most recent studies have indicated that Wnt signaling is also crucial in breast cancer immune microenvironment regulation, stemness maintenance, therapeutic resistance, phenotype shaping, etc. Wnt/β-Catenin, Wnt-planar cell polarity (PCP), and Wnt-Ca2+ signaling are three well-established Wnt signaling pathways that share overlapping components and play different roles in breast cancer progression. In this review, we summarize the main findings concerning the relationship between Wnt signaling and breast cancer and provide an overview of existing mechanisms, challenges, and potential opportunities for advancing the therapy and diagnosis of breast cancer.

Cell-surface heparan sulfate proteoglycans as multifunctional integrators of signaling in cancer

Proteoglycans (PGs) represent a large proportion of the components that constitute the extracellular matrix (ECM). They are a diverse group of glycoproteins characterized by a covalent link to a specific glycosaminoglycan type. As part of the ECM, heparan sulfate (HS)PGs participate in both physiological and pathological processes including cell recruitment during inflammation and the promotion of cell proliferation, adhesion and motility during development, angiogenesis, wound repair and tumor progression. A key function of HSPGs is their ability to modulate the expression and function of cytokines, chemokines, growth factors, morphogens, and adhesion molecules. This is due to their capacity to act as ligands or co-receptors for various signal-transducing receptors, affecting pathways such as FGF, VEGF, chemokines, integrins, Wnt, notch, IL-6/JAK-STAT3, and NF-κB. The activation of those pathways has been implicated in the induction, progression, and malignancy of a tumor. For many years, the study of signaling has allowed for designing specific drugs targeting these pathways for cancer treatment, with very positive results. Likewise, HSPGs have become the subject of cancer research and are increasingly recognized as important therapeutic targets. Although they have been studied in a variety of preclinical and experimental models, their mechanism of action in malignancy still needs to be more clearly defined. In this review, we discuss the role of cell-surface HSPGs as pleiotropic modulators of signaling in cancer and identify them as promising markers and targets for cancer treatment.

Syndecan-1 and Glypican-1 Knockout Alters Body Water Balance and Urine Response to Fluid Challenge in Mice

Syndecan-1 (Sdc-1) and glypican-1 (Gpc-1) are 2 important proteoglycans found in the glycocalyx and believed to govern transvascular distribution of fluid and protein. In this translational study, we assessed Sdc-1 and Gpc-1 knockout (KO) on whole body water balance after an intravenous volume challenge. Sdc-1 and Gpc-1 KO mice had higher starting blood water content versus strain-matched controls. Sdc-1 KO mice exhibited a significantly higher diuretic response (87%; p < 0.05), higher excreted volume/infusion volume ratio (p < 0.01), higher extravascular/infused ratio, and greater tissue water concentration (60 vs. 52%). Collectively, these suggest differences in kidney response and greater fluid efflux from peripheral vessels. The CD1 strain and Gpc-1 KO had a 2-3-fold larger urine output relative to C57 strain, but Gpc-1 KO reduced the excreted/infused ratio relative to controls (p < 0.01) and they maintained plasma dilution longer. Thus, genetic KO of Sdc-1 and Gpc-1 resulted in markedly different phenotypes. This work establishes the feasibility of performing fluid balance studies in mice.

Role of syndecan-1 in the interaction between dendritic cells and T cells

Syndecan-1 (Sdc-1) is a heparan sulfate proteoglycan that can bind cytokines and chemokines via its heparan sulfate side chains, and has immunomodulatory properties in experimental models. Sdc-1 expression has been reported on dendritic cells (DC) and T cells. The potential role of Sdc-1 in DC-T cell interaction has not been investigated yet. We postulate that Sdc-1 is involved in DC-T cell interaction and may influence graft survival in an allogeneic transplant model. Sdc-1 expression on bone marrow-derived DC and T cells was analyzed by flow cytometry. Unstimulated and LPS stimulated Sdc-1 deficient DC were evaluated in vitro for phenotype and stimulatory capacity in mixed lymphocyte reaction. Sdc-1 deficient T cells were evaluated for proliferative capacity and differentiation in a mixed lymphocyte reaction and a proliferation assay. Allograft survival was evaluated in a fully MHC mismatched heterotopic heart transplant model, with either Sdc-1 deficient donors or recipients. Sdc-1 was expressed on the cell surface of unstimulated and LPS matured DC. Sdc-1 deficiency had no effect on expression of co-stimulatory molecules, cytokine production or T cell stimulatory capacity as compared to WT DC. Sdc-1 expression was not detectable on WT T cells, although intracellular Sdc-1 expression could be demonstrated after ConA activation. Sdc-1 deficient T cells showed reduced proliferation upon DC or ConA stimulation and reduced IL-17 production upon ConA stimulation, compared to WT T cells. Sdc-1 deficiency of either allograft or recipient did not prolong allograft survival. In conclusion, Sdc-1 is expressed on the cell surface of DC, where its absence does not affect DC phenotype or T cell stimulatory capacity. Sdc-1 is intracellularly expressed in ConA activated T cells. Sdc-1 deficiency in T cells results in a reduced proliferative response in vitro, as induced by DC and ConA. Sdc-1 deficiency in donor or recipient does not affect allograft survival.

Heparanase Promotes Syndecan-1 Expression to Mediate Fibrillar Collagen and Mammographic Density in Human Breast Tissue Cultured ex vivo

Mammographic density (MD) is a strong and independent factor for breast cancer (BC) risk and is increasingly associated with BC progression. We have previously shown in mice that high MD, which is characterized by the preponderance of a fibrous stroma, facilitates BC xenograft growth and metastasis. This stroma is rich in extracellular matrix (ECM) factors, including heparan sulfate proteoglycans (HSPGs), such as the BC-associated syndecan-1 (SDC1). These proteoglycans tether growth factors, which are released by heparanase (HPSE). MD is positively associated with estrogen exposure and, in cell models, estrogen has been implicated in the upregulation of HPSE, the activity of which promotes SDC expression. Herein we describe a novel measurement approach (single-sided NMR) using a patient-derived explant (PDE) model of normal human (female) mammary tissue cultured ex vivo to investigate the role(s) of HPSE and SDC1 on MD. Relative HSPG gene and protein analyses determined in patient-paired high vs. low MD tissues identified SDC1 and SDC4 as potential mediators of MD. Using the PDE model we demonstrate that HPSE promotes SDC1 rather than SDC4 expression and cleavage, leading to increased MD. In this model system, synstatin (SSTN), an SDC1 inhibitory peptide designed to decouple SDC1-ITGαvβ3 parallel collagen alignment, reduced the abundance of fibrillar collagen as assessed by picrosirius red viewed under polarized light, and reduced MD. Our results reveal a potential role for HPSE in maintaining MD via its direct regulation of SDC1, which in turn physically tethers collagen into aligned fibers characteristic of MD. We propose that inhibitors of HPSE and/or SDC1 may afford an opportunity to reduce MD in high BC risk individuals and reduce MD-associated BC progression in conjunction with established BC therapies.

The heparan sulfate proteoglycan syndecan-1 regulates colon cancer stem cell function via a focal adhesion kinase-Wnt signaling axis

In colon cancer, downregulation of the transmembrane heparan sulfate proteoglycan syndecan-1 (Sdc-1) is associated with increased invasiveness, metastasis, and dedifferentiation. As Sdc-1 modulates signaling pathways relevant to stem cell function, we tested the hypothesis that it may regulate a tumor-initiating cell phenotype. Sdc-1 small-interfering RNA knockdown in the human colon cancer cell lines Caco2 and HT-29 resulted in an increased side population (SP), enhanced aldehyde dehydrogenase 1 activity, and higher expression of CD133, LGR5, EPCAM, NANOG, SRY (sex-determining region Y)-box 2, KLF2, and TCF4/TCF7L2. Sdc-1 knockdown enhanced sphere formation, cell viability, Matrigel invasiveness, and epithelial-to-mesenchymal transition-related gene expression. Sdc-1-depleted HT-29 xenograft growth was increased compared to controls. Decreased Sdc-1 expression was associated with an increased activation of β1-integrins, focal adhesion kinase (FAK), and wingless-type (Wnt) signaling. Pharmacological FAK and Wnt inhibition blocked the enhanced stem cell phenotype and invasive growth. Sequential flow cytometric SP enrichment substantially enhanced the stem cell phenotype of Sdc-1-depleted cells, which showed increased resistance to doxorubicin chemotherapy and irradiation. In conclusion, Sdc-1 depletion cooperatively enhances activation of integrins and FAK, which then generates signals for increased invasiveness and cancer stem cell properties. Our findings may provide a novel concept to target a stemness-associated signaling axis as a therapeutic strategy to reduce metastatic spread and cancer recurrence. DATABASES: The GEO accession number of the Affymetrix transcriptomic screening is GSE58751.

R-spondins engage heparan sulfate proteoglycans to potentiate WNT signaling

R-spondins (RSPOs) amplify WNT signaling during development and regenerative responses. We previously demonstrated that RSPOs 2 and 3 potentiate WNT/β-catenin signaling in cells lacking leucine-rich repeat-containing G-protein coupled receptors (LGRs) 4, 5 and 6 (Lebensohn and Rohatgi, 2018). We now show that heparan sulfate proteoglycans (HSPGs) act as alternative co-receptors for RSPO3 using a combination of ligand mutagenesis and ligand engineering. Mutations in RSPO3 residues predicted to contact HSPGs impair its signaling capacity. Conversely, the HSPG-binding domains of RSPO3 can be entirely replaced with an antibody that recognizes heparan sulfate (HS) chains attached to multiple HSPGs without diminishing WNT-potentiating activity in cultured cells and intestinal organoids. A genome-wide screen for mediators of RSPO3 signaling in cells lacking LGRs 4, 5 and 6 failed to reveal other receptors. We conclude that HSPGs are RSPO co-receptors that potentiate WNT signaling in the presence and absence of LGRs.

The Tumor Microenvironment: Focus on Extracellular Matrix

The extracellular matrix (ECM) regulates the development and maintains tissue homeostasis. The ECM is composed of a complex network of molecules presenting distinct biochemical properties to regulate cell growth, survival, motility, and differentiation. Among their components, proteoglycans (PGs) are considered one of the main components of ECM. Its composition, biomechanics, and anisotropy are exquisitely tuned to reflect the physiological state of the tissue. The loss of ECM's homeostasis is seen as one of the hallmarks of cancer and, typically, defines transitional events in tumor progression and metastasis. In this chapter, we discuss the types of proteoglycans and their roles in cancer. It has been observed that the amount of some ECM components is increased, while others are decreased, depending on the type of tumor. However, both conditions corroborate with tumor progression and malignancy. Therefore, ECM components have an increasingly important role in carcinogenesis and this leads us to believe that their understanding may be a key in the discovery of new anti-tumor therapies. In this book, the main ECM components will be discussed in more detail in each chapter.

Relationship between SDC1 and cadherin signalling activation in cancer

E-cadherin and SDC1 are markers of epithelial-to-mesenchymal transition (EMT) that can be used to assess tumour prognosis. SDC1 has different effects in various types of cancers. On the one hand, reduced expression of SDC1 can leads to advantage stages of some cancers, such as gastric and colorectal cancer. On the other hand, SDC1 overexpression can also promote the growth and proliferation of cancer cells in pancreatic and breast cancer. However, the function of SDC1 is influenced and regulated by many factors. Exfoliated extracellular domain HS chain can mediate the function of SDC1 and play an important role in the occurrence and development of cancer. SDC1 binds to various ligands and influences the growth and reproduction of cancer cells via the activation of Wnt, the long isoform of FLICE-inhibitory protein (FLIP long), vascular endothelial growth factor receptor (VEGFR), mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) and MAPK/c-Jun N-terminal kinase (JNK) and other pathways. Cadherins occur in several types, but this review focuses on classical cadherins. N-cadherin and P-cadherin are activated during tumour development, whereas E-cadherin is a tumour suppressor. The cellular signalling pathways involved in classical cadherins, such as Wnt and VEGFR pathways, are also related to SDC1. The activation of E-cadherin caused by SDC1 knockdown has also been observed. Despite this evidence, no articles regarding the relationship of SDC1 and cadherin activation have been published. This review summarises the expressions of these two molecules in different cancers and analyses their possible relationship to provide insights into future cancer research and clinical treatment.

A shift from membranous and stromal syndecan-1 (CD138) expression to cytoplasmic CD138 expression is associated with poor prognosis in breast cancer

Syndecan-1 (CD138) is a transmembrane proteoglycan expressed in normal and malignant tissues. It is of interest because of a possible prognostic effect in tumors and as a target for Indatuximab, a monoclonal antibody coupled to a cytotoxic agent. To assess the prognostic role of CD138 expression in breast cancer (BCa), a tissue microarray containing 1535 BCa specimens was analyzed by immunohistochemistry. Cytoplasmic, membranous, and stromal CD138 staining was separately analyzed. In normal breast tissue, CD138 staining was limited to epithelial cell membranes. In cancers, membranous staining tended to become weaker or even disappeared (38.3% of cancers with absence of membranous staining) but cytoplasmic and stromal staining newly appeared in 29.7% and 58.1% of cancers. Loss of membranous epithelial CD138 staining as well as presence of cytoplasmic and stromal CD138 positivity were-to a variable degree-associated with high pT, high grade, nodal metastasis, estrogen receptor-negative, progesterone receptor-negative, human epidermal growth factor receptor 2+, and poor overall patient survival. A combined analysis of epithelial and stromal CD138 expression revealed a link to overall patient survival (P < .0001) with best prognosis for patients with stromal positivity and absence of cytoplasmic staining, the worst prognosis for cancers with cytoplasmic staining and stromal negativity and intermediate prognosis for patients having either cytoplasmic staining or stromal negativity. In multivariate analyses, CD138 was not independent of established prognostic features. In summary, these data reveal a compartment depending prognostic effect of CD138 expression in BCa with cytoplasmic positivity being linked to aggressive cancer and stromal CD138 being linked to a more favorable prognosis.

Dynamic CD138 surface expression regulates switch between myeloma growth and dissemination

The canonical plasma cell marker CD138 (syndecan-1) is highly expressed on the myeloma cell surface, but its functional role in vivo is unclear, as well as the ontogeny of CD138-high and CD138-negative (neg) myeloma cells. In this study we used an in vivo murine Vk*MYC myeloma model where CD138 is heterogeneously expressed depending on tumor size. We find that in comparison to CD138-neg myeloma cells, the CD138-high subset of myeloma cells is highly proliferative, less apoptotic, and enhanced IL-6R signaling, which is known to promote survival. In addition CD138-high myeloma engrafts better than its CD138-neg counterpart. In contrast, CD138-neg cells are more motile both in vitro and in vivo, and more readily disseminate and spread to other bones in vivo than CD138-high subset. Neutralizing CD138 rapidly triggers migration of myeloma cells in vivo and leads to intravasation, which results in increased dissemination to other bones. Both murine and human myeloma cells can rapidly recycle CD138 surface expression through endocytic trafficking, in response to serum levels. Blocking CD138 enhances myeloma sensitivity to bortezomib chemotherapy and significantly reduces tumor size compared to bortezomib treatment alone. Thus, our data show that CD138 surface expression dynamically regulates a switch between growth vs. dissemination for myeloma, in response to nutrient conditions.

Syndecan-1 promotes lung fibrosis by regulating epithelial reprogramming through extracellular vesicles

Idiopathic pulmonary fibrosis (IPF) is a chronic and fatal lung disease. A maladaptive epithelium due to chronic injury is a prominent feature and contributor to pathogenic cellular communication in IPF. Recent data highlight the concept of a "reprogrammed" lung epithelium as critical in the development of lung fibrosis. Extracellular vesicles (EVs) are potent mediator of cellular crosstalk, and recent evidence supports their role in lung pathologies such as IPF. Here, we demonstrate that syndecan-1 is overexpressed by the epithelium in the lungs of IPF patients and in murine models after bleomycin injury. Moreover, we find that syndecan-1 is a pro-fibrotic signal that alters alveolar type II (ATII) cell phenotypes by augmenting TGFβ and Wnt signaling among other pro-fibrotic pathways. Importantly, we demonstrate that syndecan-1 controls the packaging of several anti-fibrotic microRNAs into EVs that have broad effects over several fibrogenic signaling networks as a mechanism of regulating epithelial plasticity and pulmonary fibrosis. Collectively, our work reveals new insight into how EVs orchestrate cellular signals that promote lung fibrosis and demonstrate the importance of syndecan-1 in coordinating these programs.

Syndecan-1 facilitates breast cancer metastasis to the brain

PURPOSE

Although survival rates for patients with localized breast cancer have increased, patients with metastatic breast cancer still have poor prognosis. Understanding key factors involved in promoting breast cancer metastasis is imperative for better treatments. In this study, we investigated the role of syndecan-1 (Sdc1) in breast cancer metastasis.

METHODS

To assess the role of Sdc1 in breast cancer metastasis, we silenced Sdc1 expression in the triple-negative breast cancer human MDA-MB-231 cell line and overexpressed it in the mouse mammary carcinoma 4T1 cell line. Intracardiac injections were performed in an experimental mouse metastasis model using both cell lines. In vitro transwell blood-brain barrier (BBB) and brain section adhesion assays were utilized to specifically investigate how Sdc1 facilitates brain metastasis. A cytokine array was performed to evaluate differences in the breast cancer cell secretome when Sdc1 is silenced.

RESULTS

Silencing expression of Sdc1 in breast cancer cells significantly reduced metastasis to the brain. Conversely, overexpression of Sdc1 increased metastasis to the brain. We found that silencing of Sdc1 expression had no effect on attachment of breast cancer cells to brain endothelial cells or astrocytes, but migration across the BBB was reduced as well as adhesion to the perivascular regions of the brain. Loss of Sdc1 also led to changes in breast cancer cell-secreted cytokines/chemokines, which may influence the BBB.

CONCLUSIONS

Taken together, our study demonstrates a role for Sdc1 in promoting breast cancer metastasis to the brain. These findings suggest that Sdc1 supports breast cancer cell migration across the BBB through regulation of cytokines, which may modulate the BBB. Further elucidating this mechanism will allow for the development of therapeutic strategies to combat brain metastasis.

New SDC function prediction based on protein-protein interaction using bioinformatics tools

The precise roles for SDC have been complex to specify. Assigning and reanalyzing protein and peptide identification to novel protein functions is one of the most important challenges in postgenomic era. Here, we provide SDC molecular description to support, contextualize and reanalyze the corresponding protein-protein interaction (PPI). From SDC-1 data mining, we discuss the potential of bioinformatics tools to predict new biological rules of SDC. Using these methods, we have assembled new possibilities for SDC biology from PPI data, once, the understanding of biology complexity cannot be capture from one simple question.

Metabolic and behavioral parameters of mice with reduced expression of Syndecan-1

Energy balance is essential for all species. Ligand-receptor interactions mediate processes that regulate body activities like reproduction and metabolism based on the energy status. Such receptors are the heparan sulfate proteoglycans and specifically the family of syndecans. Therefore we investigated the differences of metabolic parameters of heterozygous Syndecan 1 mice (Sdc1^+/-) with reduced expression of Sdc1 and the corresponding wild type mice. Sdc1^+/- mice have a reduced body weight although they show increased leptin and decreased corticosterone levels. Furthermore, their food and water intake is increased. This is accompanied with less adipose tissue, smaller adipocytes and thus an increased density of adipocytes. For the detailed analysis of the metabolism the automated PhenoMaster system has been used, which allowed continuous and undisturbed recording of food and water intake, energy expenditure and movement. The reason for the lower body weight was the higher energy expenditure of these animals compared to controls. Additionally, female Sdc1^+/- mice showed an increased locomotor activity. Referring to organs, the intestine in Sdc1^+/- mice was heavier and longer, but no differences at the cellular level could be observed. These findings were independent of normal mating or vice versa embryo transfers of Sdc1^+/- and wild type embryos in recipient females of the other genotype. Herein we showed that the reduced expression of Sdc1 led to an altered metabolism on fetal as well as on maternal side, which may play a role in the growth restriction observed in human pregnancy pathologies and in mice lacking Sdc1.

Estrogen receptor α regulates the expression of syndecan-1 in human breast carcinoma cells

Breast cancer (BC) is the primary cause of cancer-related mortality among women. Patients who express the estrogen receptor (ER), which mediates the tumorigenic effects of estrogens, respond to antihormonal therapy. Loss of ER expression or acquired resistance to E2 is associated with aggressive malignant phenotypes, which lead to relapse. These BC subtypes overexpress syndecan-1 (SDC1), a transmembrane heparan sulfate proteoglycan that mediates angiogenesis as well as the proliferation and invasiveness of cancer cells. We showed here that the activation of ER-alpha (ERα) by estrogens induces downregulation of SDC1 expression in ER(+) MCF7 cells but not in T47D cells. Loss of ERα expression, induced by RNA interference or a selective ER downregulator, led to subsequent SDC1 overexpression. E2-dependent downregulation of SDC1 expression required de novo protein synthesis and was antagonized by treatment with BAY 11-7085, an irreversible inhibitor of IκBα phosphorylation, which inhibits the activation of NFκB. Downregulation of SDC1 expression required ERα and activation of IKK, but was independent to downstream transcriptional regulators of NFκB. BAY 11-7085 prevented E2-mediated phosphorylation of ERα on Ser118, increasing its proteasomal degradation, suggesting that IKK stabilized E2-activated ERα, leading to subsequent downregulation of SDC1 expression. Our results showed that sustained ER signaling inhibits SDC1 expression. Such antagonism elucidates the inverse correlation between SDC1 and ER expression in ER(+) BC as well as the overexpression of SDC1 in hormone receptor-negative BC subtypes with the most aggressive phenotypes. These results identify SDC1 as an attractive therapeutic target for BC as well as for other endocrine-associated cancers.

Syndecan 1 is a critical mediator of macropinocytosis in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) remains recalcitrant to all forms of cancer treatment and carries a dismal 5-year survival rate of 8%¹. Inhibition of oncogenic KRAS (hereafter KRAS*), the earliest lesion in disease development that is present in >90% of PDAC, and its signaling surrogates has yielded encouraging preclinical results with experimental agents^2-4. However, KRAS*-independent disease recurrence following genetic extinction of Kras* in mouse models anticipates the need for co-extinction strategies^5,6. Multiple oncogenic processes are initiated at the cell surface, where KRAS* physically and functionally interacts to direct signaling essential for malignant transformation and tumor maintenance. Insights into the complexity of the functional surfaceome have been technologically limited until recently, and, in the case of PDAC, the genetic control of the function and composition of the PDAC surfaceome in the context of KRAS* signaling remains largely unexplored. Here, we developed an unbiased, functional target discovery platform to query KRAS*-dependent changes of the PDAC surfaceome, which uncovered syndecan-1 (SDC1) as a protein upregulated at the cell surface by KRAS*. Cell surface localization of SDC1 is essential for disease maintenance and progression, where it regulates macropinocytosis, an essential metabolic pathway that fuels PDAC cell growth. Thus, our study forges a mechanistic link between KRAS* signaling and a targetable molecule driving nutrient salvage pathways in PDAC and validates oncogene-driven surfaceome annotation as a strategy to identify cancer-specific vulnerabilities.

Physiological and anatomical aspects of the reproduction of mice with reduced Syndecan-1 expression

BACKGROUND

Syndecan-1 is a heparan sulfate proteoglycan acting as a co-receptor for cytokines and growth factors mediating developmental, immunological and angiogenic processes. In human, the uteroplacental localization of Syndecan-1 and its reduced expression in pregnancy-associated pathologies, such as the intrauterine growth restriction, suggests an influence of Syndecan-1 in embryo-maternal interactions. The aim of the present study was to identify the effect of a reduced expression of Syndecan-1 on the reproductive phenotype of mice and their progenies.

METHODS

Reproductive characteristics have been investigated using animals with reduced Syndecan-1 and their wildtype controls after normal mating and after vice versa embryo transfers. Female mice were used to measure the estrus cycle length and the weight gain during pregnancy, as well as for histological examination of ovaries. Male mice were examined for the concentration, motility, viability and morphology of spermatozoa. Organs like heart, lung, liver, kidney, spleen, brain and ovaries or testes and epididymis of 6-month-old animals were isolated and weighed. Statistical analyses were performed using two-tailed students t-test with P < .05 and P < .02, chi square test (P < .05) and Fisher's Exact Test (P < .05). A linear and a non-linear mixed-effects model were generated to analyze the weight gain of pregnant females and of the progenies.

RESULTS

Focusing on the pregnancy outcome, the Syndecan-1 reduced females gave birth to larger litters. However, regarding the survival of the offspring, a higher percentage of pups with less Syndecan-1 died during the first postnatal days. Even though the ovaries and the testes of Syndecan-1 reduced mice showed no histological differences and the ovaries showed a similar number of primary and secondary follicles and corpora lutea, the spermatozoa of Syndecan-1 reduced males showed more tail and midpiece deficiencies. Concerning the postnatal and juvenile development the pups with reduced Syndecan-1 expression remained lighter and smaller regardless whether carried by mothers with reduced Syndecan-1 or wildtype foster mothers. With respect to anatomical differences kidneys of both genders as well as testes and epididymis of male mice with reduced syndecan-1 expression weighed less compared to controls.

CONCLUSIONS

These data reveal that the effects of Syndecan-1 reduction are rather genotype- than parental-dependent.

Mechanisms of Wnt signaling and control

The Wnt signaling pathway is a highly conserved system that regulates complex biological processes across all metazoan species. At the cellular level, secreted Wnt proteins serve to break symmetry and provide cells with positional information that is critical to the patterning of the entire body plan. At the organismal level, Wnt signals are employed to orchestrate fundamental developmental processes, including the specification of the anterior-posterior body axis, induction of the primitive streak and ensuing gastrulation movements, and the generation of cell and tissue diversity. Wnt functions extend into adulthood where they regulate stem cell behavior, tissue homeostasis, and damage repair. Disruption of Wnt signaling activity during embryonic development or in adults results in a spectrum of abnormalities and diseases, including cancer. The molecular mechanisms that underlie the myriad of Wnt-regulated biological effects have been the subject of intense research for over three decades. This review is intended to summarize our current understanding of how Wnt signals are generated and interpreted. This article is categorized under: Biological Mechanisms > Cell Signaling Developmental Biology > Stem Cell Biology and Regeneration.

Cancer Cell Glycocalyx and Its Significance in Cancer Progression

Cancer is a malignant tumor that threatens the health of human beings, and has become the leading cause of death in urban and rural residents in China. The glycocalyx is a layer of multifunctional glycans that covers the surfaces of a variety of cells, including vascular endothelial cells, smooth muscle cells, stem cells, epithelial, osteocytes, as well as cancer cells. The glycosylation and syndecan of cancer cell glycocalyx are unique. However, heparan sulfate (HS), hyaluronic acid (HA), and syndecan are all closely associated with the processes of cancer progression, including cell migration and metastasis, tumor cell adhesion, tumorigenesis, and tumor growth. The possible underlying mechanisms may be the interruption of its barrier function, its radical role in growth factor storage, signaling, and mechanotransduction. In the later sections, we discuss glycocalyx targeting therapeutic approaches reported in animal and clinical experiments. The study concludes that cancer cells’ glycocalyx and its role in cancer progression are beginning to be known by more groups, and future studies should pay more attention to its mechanotransduction of interstitial flow-induced shear stress, seeking promising therapeutic targets with less toxicity but more specificity.

Syndecan-1 induction in lung microenvironment supports the establishment of breast tumor metastases

Background

Syndecan-1 (Sdc1), a cell surface heparan sulfate proteoglycan normally expressed primarily by epithelia and plasma cells, is aberrantly induced in stromal fibroblasts of breast carcinomas. Stromal fibroblast-derived Sdc1 participates in paracrine growth stimulation of breast carcinoma cells and orchestrates stromal extracellular matrix fiber alignment, thereby creating a migration and invasion-permissive microenvironment. Here, we specifically tested the role of stromal Sdc1 in metastasis.

Methods

The metastatic potential of the aggressive mouse mammary carcinoma cell lines, 4T1 and E0776, was tested in wild-type and genetically Sdc1-deficient host animals. Metastatic lesions were characterized by immunohistochemical analysis.

Results

After orthotopic inoculation, the lung metastatic burden was reduced in Sdc1−/− animals by 97% and more than 99%, in BALB/cJ and C57BL/6 animals, respectively. The difference in metastatic efficiency was maintained when the tumor cells were injected into the tail vein, suggesting that host Sdc1 exerts its effect during later stages of the metastatic cascade. Co-localization studies identified Sdc1 expression in stromal fibroblasts within the metastatic microenvironment and in normal airway epithelial cells but not in other cells (endothelial cells, α-smooth muscle actin positive cells, leucocytes, macrophages). The Ki67 proliferation index and the rate of apoptosis of the metastatic tumor cells were diminished in Sdc1−/− vs. Sdc1+/+ animals, and leucocyte density was indistinguishable. Sdc1-mediated metastatic efficiency was abolished when the animals were housed at a thermoneutral ambient temperature of 31 °C, suggesting that the host Sdc1 effect on metastasis requires mild cold stress.

Conclusions

In summary, Sdc1 is induced in the lung microenvironment after mammary carcinoma cell dissemination and promotes outgrowth of metastases in a temperature-dependent manner.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-0995-x) contains supplementary material, which is available to authorized users.

Increased soluble heterologous expression of a rat brain 3-O-sulfotransferase 1 - A key enzyme for heparin biosynthesis

Heparan sulfate (HS), is a glycosaminoglycan (GAG) involved in various biological processes, including blood coagulation, wound healing and embryonic development. HS 3-O-sulfotransferases (3-OST), which transfer the sulfo group to the 3-hydroxyl group of certain glucosamine residues, is a key enzyme in the biosynthesis of a number of biologically important HS chains. The 3-OST-1 isoform is one of the 7 known 3-OST isoforms and is important for the biosynthesis of anticoagulant HS chains. In this study, we cloned 3-OST-1 from the rat brain by reverse transcription-polymerase chain reaction (RT-PCR). After codon optimization and removal of the signal peptide, the recombinant plasmid was transformed into Escherichia coli BL21 (DE3) to obtain a His tagged-3-OST-1 fusion protein. SDS-PAGE analysis showed that the expressed 3-OST-1 was mainly found in inclusion bodies. The 3-OST-1 was purified by Ni affinity column and refolded by dialysis. The activity of obtained 3-OST-1 was 0.04 U/mL with a specific activity of 0.55 U/mg after renaturation. Furthermore, a co-expressed recombinant plasmid pET-28a-3-OST-1 with the chaperone expression system (pGro7) was constructed and transferred to E. coli BL21 (DE3) to co-express recombinant strain E. coli BL21 (DE3)/pET-28a-3-OST-1 + pGro7. The soluble expression of 3-OST-1 was significantly improved in the co-expressed recombinant strain, with enzyme activity reaching 0.06 U/mL and having a specific activity of 0.83 U/mg. N-sulfo, N-acetylheparosan (NSNAH) was modified by the recombinant expressed 3-OST-1 and the product was confirmed by ¹H NMR showing the sulfo group was successfully transferred to NSNAH.

Identification of key genes and pathways in uterine leiomyosarcoma through bioinformatics analysis

Uterine leiomyosarcoma (uLMS) is a rare but malignant gynaecological tumour with a poor survival outcome. The present study was aimed at identifying the key genes and pathways in the development of uLMS through bioinformatics analysis. To minimize the frequency of false-positive results of the bioinformatics analysis, 3 microarrays including GSE764, GSE64763 and GSE68312 were downloaded from Gene Expression Omnibus (GEO). Differentially expressed genes (DEGs) were screened out using the online tool GEO2R. Then, Gene Ontology and Kyoto Encyclopaedia of Genes and Genomes pathway enrichment analyses were performed using the Database for Annotation, Visualization and Integrated Discovery. Finally, a protein-protein interaction (PPI) network of the DEGs was constructed using Cytoscape, and module analysis was conducted using the plug-in MCODE. A total of 95 DEGs including 21 upregulated genes and 74 downregulated genes were identified. The upregulated DEGs were annotated with 'DNA metabolic process', 'nucleobase-containing compound biosynthetic process' and 'cellular macromolecule biosynthetic process', while the downregulated DEGs were annotated with 'cellular response to chemical stimulus', 'movement of cell or subcellular component' and 'response to inorganic substances'. The results of the PPI network analysis demonstrated that matrix metallopeptidase 9, apolipoprotein E, cyclin E1 and syndecan 1 were the predominant upregulated genes in uLMS. Additionally, the genes in the main module were enriched in 'proteoglycans in cancer', 'p53 signalling pathway' and 'extracellular matrix-receptor interaction'. The key genes and pathways identified in the present study may provide valuable clues for clarifying the molecular mechanism underlying the development of uLMS and demonstrate promise for use as diagnostic markers and therapeutic targets.

Drosophila Glypicans Regulate Follicle Stem Cell Maintenance and Niche Competition

Adult stem cells reside in specialized microenvironments called niches, which provide signals for stem cells to maintain their undifferentiated and self-renewing state. To maintain stem cell quality, several types of stem cells are known to be regularly replaced by progenitor cells through niche competition. However, the cellular and molecular bases for stem cell competition for niche occupancy are largely unknown. Here, we show that two Drosophila members of the glypican family of heparan sulfate proteoglycans (HSPGs), Dally and Dally-like (Dlp), differentially regulate follicle stem cell (FSC) maintenance and competitiveness for niche occupancy. Lineage analyses of glypican mutant FSC clones showed that dally is essential for normal FSC maintenance. In contrast, dlp is a hypercompetitive mutation: dlp mutant FSC progenitors often eventually occupy the entire epithelial sheet. RNA interference knockdown experiments showed that Dally and Dlp play both partially redundant and distinct roles in regulating Jak/Stat, Wg, and Hh signaling in FSCs. The Drosophila FSC system offers a powerful genetic model to study the mechanisms by which HSPGs exert specific functions in stem cell replacement and competition.

Syndecans in chronic inflammatory and autoimmune diseases: Pathological insights and therapeutic opportunities

Syndecans (SDCs) are a family of heparan sulfate proteoglycans (HSPGs) glycoproteins ubiquitously expressed on the cell surfaces and extracellular matrix of all mammalian tissues. There are four mammalian syndecans, SDC-1 thorough 4, which play a critical role in cell adhesion, migration, proliferation, differentiation, and angiogenesis through independent and growth factor mediated signaling. An altered expression of SDCs is often observed in autoimmune disorders, cancer, HIV infection, and many other pathological conditions. SDCs modulate disease progression by interacting with a diverse array of ligands, receptors, and other proteins, including extracellular matrix, glycoproteins, integrins, morphogens, and various growth factors and chemokines, along with their receptors and kinases. Specifically, SDCs present on cell surface can bind directly to chemokines to enhance their binding to receptors, downstream signaling, and migration. Alternatively, SDCs can be cleaved and shed to mediate negative regulation of chemokine and growth factor signaling pathways and ligand sequestration. Importantly, SDC shedding may be a biomarker of inflammation, especially in chronic inflammatory diseases. While the current therapies for cancer and several autoimmune disorders have revolutionized treatment outcomes, understanding the pathophysiological role of SDCs and the use of HSPG mimetic or antagonists on cytokine signaling networks may uncover potentially novel targeted therapeutic approaches. This review mainly summarizes the current findings on the role of individual SDCs in disease processes, mechanisms through which SDCs mediate their biological functions, and the possibility of targeting SDCs as future potential therapeutic approaches.

Syndecan-1 promotes Wnt/β-catenin signaling in multiple myeloma by presenting Wnts and R-spondins

HS chains decorating syndecan-1 promote autocrine and paracrine Wnt signaling in MM. Loss of HS inhibits MM cell growth by attenuating Wnt signaling.