Syndecans in tumor cell adhesion and signaling

Shaping Oncogenic Microenvironments: Contribution of Fibronectin

The extracellular matrix (ECM) is a complex network of proteins and glycans, dynamically remodeled and specifically tailored to the structure/function of each organ. The malignant transformation of cancer cells is determined by both cell intrinsic properties, such as mutations, and extrinsic variables, such as the mixture of surrounding cells in the tumor microenvironment and the biophysics of the ECM. During cancer progression, the ECM undergoes extensive remodeling, characterized by disruption of the basal lamina, vascular endothelial cell invasion, and development of fibrosis in and around the tumor cells resulting in increased tissue stiffness. This enhanced rigidity leads to aberrant mechanotransduction and further malignant transformation potentiating the de-differentiation, proliferation and invasion of tumor cells. Interestingly, this fibrotic microenvironment is primarily secreted and assembled by non-cancerous cells. Among them, the cancer-associated fibroblasts (CAFs) play a central role. CAFs massively produce fibronectin together with type I collagen. This review delves into the primary interactions and signaling pathways through which fibronectin can support tumorigenesis and metastasis, aiming to provide critical molecular insights for better therapy response prediction.

Sarcoma microenvironment cell states and ecosystems are associated with prognosis and predict response to immunotherapy

Characterization of the diverse malignant and stromal cell states that make up soft tissue sarcomas and their correlation with patient outcomes has proven difficult using fixed clinical specimens. Here, we employed EcoTyper, a machine-learning framework, to identify the fundamental cell states and cellular ecosystems that make up sarcomas on a large scale using bulk transcriptomes with clinical annotations. We identified and validated 23 sarcoma-specific, transcriptionally defined cell states, many of which were highly prognostic of patient outcomes across independent datasets. We discovered three conserved cellular communities or ecotypes associated with underlying genomic alterations and distinct clinical outcomes. We show that one ecotype defined by tumor-associated macrophages and epithelial-like malignant cells predicts response to immune-checkpoint inhibition but not chemotherapy and validate our findings in an independent cohort. Our results may enable identification of patients with soft tissue sarcomas who could benefit from immunotherapy and help develop new therapeutic strategies.

NMR Structural Study of Syndecan-4 Transmembrane Domain with Cytoplasmic Region

Syndecan-4 (SDC4) consists of transmembrane heparan sulfate proteoglycan (HSPG) belonging to the syndecan family. It is present in most cell types of Mammalia. Its structure contains a heparan-sulfate-modified extracellular domain, a single transmembrane domain, and a short C-terminal cytoplasmic domain. Regarding the overall cellular function of SDC4, other cells or ligands can bind to its ecto-domain. In addition, 4,5-bisphosphate phosphatidylinositol (PIP2) or protein kinase Cα can bind to its cyto-domain to activate downstream signaling pathways. To understand the signal transduction mechanism of syndecan, it is important to know the interactions between their actual structure and function in vivo. Therefore, it is important to identify the structure of SDC4 to understand the ligand binding behavior of SDC4. In this study, expression and purification were performed to reveal structures of the short ecto-domain, the transmembrane domain, and the cytoplasmic domain of Syd4-eTC (SDC4). Solution-state NMR spectroscopy and solid-state NMR spectroscopy were used to study the structure of Syd4-eTC in membrane environments and to demonstrate the interaction between Syd4-eTC and PIP2.

Engineered Biomimetic Fibrillar Fibronectin Matrices Regulate Cell Adhesion Initiation, Migration, and Proliferation via α5β1 Integrin and Syndecan-4 Crosstalk

Cells regulate adhesion to the fibrillar extracellular matrix (ECM) of which fibronectin is an essential component. However, most studies characterize cell adhesion to globular fibronectin substrates at time scales long after cells polarize and migrate. To overcome this limitation, a simple and scalable method to engineer biomimetic 3D fibrillar fibronectin matrices is introduced and how they are sensed by fibroblasts from the onset of attachment is characterized. Compared to globular fibronectin substrates, fibroblasts accelerate adhesion initiation and strengthening within seconds to fibrillar fibronectin matrices via α5β1 integrin and syndecan-4. This regulation, which additionally accelerates on stiffened fibrillar matrices, involves actin polymerization, actomyosin contraction, and the cytoplasmic proteins paxillin, focal adhesion kinase, and phosphoinositide 3-kinase. Furthermore, this immediate sensing and adhesion of fibroblast to fibrillar fibronectin guides migration speed, persistency, and proliferation range from hours to weeks. The findings highlight that fibrillar fibronectin matrices, compared to widely-used globular fibronectin, trigger short- and long-term cell decisions very differently and urge the use of such matrices to better understand in vivo interactions of cells and ECMs. The engineered fibronectin matrices, which can be printed onto non-biological surfaces without loss of function, open avenues for various cell biological, tissue engineering and medical applications.

Extracellular Matrix of Echinoderms

This review considers available data on the composition of the extracellular matrix (ECM) in echinoderms. The connective tissue in these animals has a rather complex organization. It includes a wide range of structural ECM proteins, as well as various proteases and their inhibitors. Members of almost all major groups of collagens, various glycoproteins, and proteoglycans have been found in echinoderms. There are enzymes for the synthesis of structural proteins and their modification by polysaccharides. However, the ECM of echinoderms substantially differs from that of vertebrates by the lack of elastin, fibronectins, tenascins, and some other glycoproteins and proteoglycans. Echinoderms have a wide variety of proteinases, with serine, cysteine, aspartic, and metal peptidases identified among them. Their active centers have a typical structure and can break down various ECM molecules. Echinoderms are also distinguished by a wide range of proteinase inhibitors. The complex ECM structure and the variety of intermolecular interactions evidently explain the complexity of the mechanisms responsible for variations in the mechanical properties of connective tissue in echinoderms. These mechanisms probably depend not only on the number of cross-links between the molecules, but also on the composition of ECM and the properties of its proteins.

Increasing cancer permeability by photodynamic priming: from microenvironment to mechanotransduction signaling

The dense cancer microenvironment is a significant barrier that limits the penetration of anticancer agents, thereby restraining the efficacy of molecular and nanoscale cancer therapeutics. Developing new strategies to enhance the permeability of cancer tissues is of major interest to overcome treatment resistance. Nonetheless, early strategies based on small molecule inhibitors or matrix-degrading enzymes have led to disappointing clinical outcomes by causing increased chemotherapy toxicity and promoting disease progression. In recent years, photodynamic therapy (PDT) has emerged as a novel approach to increase the permeability of cancer tissues. By producing excessive amounts of reactive oxygen species selectively in the cancer microenvironment, PDT increases the accumulation, penetration depth, and efficacy of chemotherapeutics. Importantly, the increased cancer permeability has not been associated to increased metastasis formation. In this review, we provide novel insights into the mechanisms by which this effect, called photodynamic priming, can increase cancer permeability without promoting cell migration and dissemination. This review demonstrates that PDT oxidizes and degrades extracellular matrix proteins, reduces the capacity of cancer cells to adhere to the altered matrix, and interferes with mechanotransduction pathways that promote cancer cell migration and differentiation. Significant knowledge gaps are identified regarding the involvement of critical signaling pathways, and to which extent these events are influenced by the complicated PDT dosimetry. Addressing these knowledge gaps will be vital to further develop PDT as an adjuvant approach to improve cancer permeability, demonstrate the safety and efficacy of this priming approach, and render more cancer patients eligible to receive life-extending treatments.

Matrix proteoglycans in tumor inflammation and immunity

Cancer immunoediting progresses through elimination, equilibrium, and escape. Each of these phases is characterized by breaching, remodeling, and rebuilding tissue planes and structural barriers that engage extracellular matrix (ECM) components, in particular matrix proteoglycans. Some of the signals emanating from matrix proteoglycan remodeling are readily co-opted by the growing tumor to sustain an environment of tumor-promoting and immune-suppressive inflammation. Yet other matrix-derived cues can be viewed as part of a homeostatic response by the host, aiming to eliminate the tumor and restore tissue integrity. These latter signals may be harnessed for therapeutic purposes to tip the polarity of the tumor immune milieu toward anticancer immunity. In this review, we attempt to showcase the importance and complexity of matrix proteoglycan signaling in both cancer-restraining and cancer-promoting inflammation. We propose that the era of matrix diagnostics and therapeutics for cancer is fast approaching the clinic.

FN1 encoding fibronectin as a pivotal signaling gene for therapeutic intervention against pancreatic cancer

The delayed diagnosis of pancreatic cancer has resulted in rising mortality rate and low survival rate that can be circumvented using potent theranostics biomarkers. The treatment gets complicated with delayed detection resulting in lowered 5-year relative survival rate. In our present study, we employed systems biology approach to identify central genes that play crucial roles in tumor progression. Pancreatic cancer genes collected from various databases were used to construct a statistically significant interactome with 812 genes that was further analysed thoroughly using topological parameters and functional enrichment analysis. The significant genes in the network were then identified based on the maximum degree parameter. The overall survival analysis indicated through hazard ratio [HR] and gene expression [log Fold Change] across pancreatic adenocarcinoma revealed the critical role of FN1 [HR 1.4; log2(FC) 5.748], FGA [HR 0.78; log2(FC) 1.639] FGG [HR 0.9; log2(FC) 1.597], C3 [HR 1.1; log2(FC) 2.637], and QSOX1 [HR 1.4; log2(FC) 2.371]. The functional significance of the identified hub genes signified the enrichment of integrin cell surface interactions and proteoglycan syndecan-mediated cell signaling. The differential expression, low overall survival and functional significance of FN1 gene implied its possible role in controlling metastasis in pancreatic cancer. Furthermore, alternate splice variants of FN1 gene showed 10 protein coding transcripts with conserved cell attachment site and functional domains indicating the variants' potential role in pancreatic cancer. The strong association of the identified hub-genes can be better directed to design potential theranostics biomarkers for metastasized pancreatic tumor.

Substituted Syndecan-2-Derived Mimetic Peptides Show Improved Antitumor Activity over the Parent Syndecan-2-Derived Peptide

We previously showed that a synthetic peptide (S2-P) corresponding to a portion of the human syndecan-2 (SDC2) sequence can bind to the pro-domain of matrix metalloproteinase-7 (MMP-7) to inhibit colon cancer activities. Since S2-P had a relatively weak binding affinity for the MMP-7 pro-domain, we herein modified the amino acid sequence of S2-P to improve the anticancer potential. On the basis of the interaction structure of S2-P and MMP-7, four peptides were generated by replacing amino acids near Tyr 51, which is critical for the interaction. The SDC2-mimetic peptides harboring an Ala-to-Asp substitution at the C-terminal side of Tyr 51 (S2-D) or with an Ala-to-Phe substitution at the N-terminal side of Tyr 51 and an Ala-to-Asp substitution at the C-terminal side of Tyr 51 (S2-FE) showed improved interaction affinities for the MMP-7 pro-domain. Compared to S2-P, S2-FE was better able to inhibit the SDC2-MMP-7 interaction, the cell surface localization of MMP-7, the gelatin degradation activity of MMP-7, and the cancer activities (cell migration, invasion, and colony-forming activity) of human HCT116 colon cancer cells in vitro. In vivo, S2-FE inhibited the primary tumor growth and lung metastasis of CT26 mouse colon cancer cells in a xenograft mouse model. Together, these data suggest that S2-FE could be useful therapeutic anticancer peptides for colon cancer.

Targeting Syndecan-1: New Opportunities in Cancer Therapy

Syndecan-1 (SDC1, CD138) is one of the heparan sulfate proteoglycans and is essential for maintaining normal cell morphology, interacting with extracellular and intracellular protein repertoire as well as mediating signaling transduction upon environmental stimuli. The critical role of SDC1 in promoting tumorigenesis and metastasis has been increasingly recognized in various cancer types, implying a promising potential of utilizing SDC1 as a novel target for cancer therapy. This review summarizes the current knowledge on SDC1 structure and functions, including its role in tumor biology. We also discuss the highlights and limitations of current SDC1-targeted therapies as well as the obstacles in developing new therapeutic methods, offering our perspective on the future directions to target SDC1 for cancer treatment.

Single-molecule force spectroscopy reveals structural differences of heparan sulfate chains during binding to vitronectin

The syndecans represent an ongoing research field focused on their regulatory roles in normal and pathological conditions. The role of syndecans in cancer progression is well documented, implicating their importance in diagnosis and even proposing various potential cancer treatments. Thus, the characterization of the unbinding properties at the single-molecule level will appeal to their use as targets for therapeutics. In our study, syndecan-1 and syndecan-4 were measured during the interaction with the vitronectin HEP II binding site. Our findings show that syndecans are calcium ion dependent molecules that reveal distinct, unbinding properties indicating the alterations in the structure of heparan sulfate (HS) chains, possibly in the chain sequence or sulfation pattern. In this way, we suppose that HS chain affinity to extracellular matrix proteins may govern cancer invasion by altering the syndecans' ability to interact with cancer-related receptors present in the tumor microenvironment, thereby promoting the activation of various signaling cascades regulating tumor cell behavior.

Cryoglobulins: Identification, classification, and novel biomarkers of mysterious proteins

Cryoglobulins consist of serum immunoglobulins that precipitate below 37°C and resolubilize upon warming. The clinical triad of cryoglobulinemia usually includes purpura, weakness, and arthralgia. Cryoglobulinemic syndrome, clinically defined as a systemic vasculitis, is associated with chronic infection with hepatitis C virus (HCV) and autoimmune disorders and can evolve into B-cell malignancies. While the current literature about HCV-associated cryoglobulinemia is not very limited, little is known about the immunologic and serologic profiles of affected patients. Therefore, comprehension of the pathogenetic mechanisms underlying cryoprecipitation could be very helpful. Due to the persistence of viral antigenic stimulation, biomarkers to use after the worsening progression of HCV infection to lymphoproliferative and/or autoimmune diseases are widely needed. Laboratory methods used to detect and characterize low concentrations of cryoprecipitates and immunotyping patterns could improve patient management. The most critical factor affecting cryoglobulin testing is that the pre-analytical phase is not fully completed at 37°C.

Role of ZEB family members in proliferation, metastasis and chemoresistance of prostate cancer cells: Revealing signaling networks

Prostate cancer (PCa) is one of the leading causes of death worldwide. A variety of strategies including surgery, chemotherapy, radiotherapy and immunotherapy are applied for PCa treatment. PCa cells are responsive towards therapy at early stages, but they can obtain resistance in the advanced stage. Furthermore, their migratory ability is high in advanced stages. It seems that genetic and epigenetic factors play an important in this case. Zinc finger E-box-binding homeobox (ZEB) is a family of transcription with two key members including ZEB1 and ZEB2. ZEB family members are known due to their involvement in promoting cancer metastasis via EMT induction. Recent studies have shown their role in cancer proliferation and inducing therapy resistance. In the current review, we focus on revealing role of ZEB1 and ZEB2 in PCa. ZEB family members that are able to significantly promote proliferation and viability of cancer cells. ZEB1 and ZEB2 enhance migration and invasion of PCa cells via EMT induction. Overexpression of ZEB1 and ZEB2 is associated with poor prognosis of PCa. ZEB1 and ZEB2 upregulation occurs during PCa progression and can provide therapy resistance to cancer cells. PRMT1, Smad2, and non-coding RNAs can function as upstream mediators of the ZEB family. Besides, Bax, Bcl-2, MRP1, N-cadherin and E-cadherin can be considered as downstream targets of ZEB family in PCa.

Therapeutic potential of targeting membrane-spanning proteoglycan SDC4 in hepatocellular carcinoma

Syndecan-4 (SDC4) functions as a major endogenous membrane-associated receptor and widely regulates cytoskeleton, cell adhesion, and cell migration in human tumorigenesis and development, which represents a charming anti-cancer therapeutic target. Here, SDC4 was identified as a direct cellular target of small-molecule bufalin with anti-hepatocellular carcinoma (HCC) activity. Mechanism studies revealed that bufalin directly bond to SDC4 and selectively increased SDC4 interaction with substrate protein DEAD-box helicase 23 (DDX23) to induce HCC genomic instability. Meanwhile, pharmacological promotion of SDC4/DDX23 complex formation also inactivated matrix metalloproteinases (MMPs) and augmented p38/JNK MAPKs phosphorylation, which are highly associated with HCC proliferation and migration. Notably, specific knockdown of SDC4 or DDX23 markedly abolished bufalin-dependent inhibition of HCC proliferation and migration, indicating SDC4/DDX23 signaling axis is highly involved in the HCC process. Our results indicate that membrane-spanning proteoglycan SDC4 is a promising druggable target for HCC, and pharmacological regulation of SDC4/DDX23 signaling axis with small-molecule holds great potential to benefit HCC patients.

Biology of the Heparanase-Heparan Sulfate Axis and Its Role in Disease Pathogenesis

Cell surface proteoglycans are important constituents of the glycocalyx and participate in cell-cell and cell-extracellular matrix (ECM) interactions, enzyme activation and inhibition, and multiple signaling routes, thereby regulating cell proliferation, survival, adhesion, migration, and differentiation. Heparanase, the sole mammalian heparan sulfate degrading endoglycosidase, acts as an "activator" of HS proteoglycans, thus regulating tissue hemostasis. Heparanase is a multifaceted enzyme that together with heparan sulfate, primarily syndecan-1, drives signal transduction, immune cell activation, exosome formation, autophagy, and gene transcription via enzymatic and nonenzymatic activities. An important feature is the ability of heparanase to stimulate syndecan-1 shedding, thereby impacting cell behavior both locally and distally from its cell of origin. Heparanase releases a myriad of HS-bound growth factors, cytokines, and chemokines that are sequestered by heparan sulfate in the glycocalyx and ECM. Collectively, the heparan sulfate-heparanase axis plays pivotal roles in creating a permissive environment for cell proliferation, differentiation, and function, often resulting in the pathogenesis of diseases such as cancer, inflammation, endotheliitis, kidney dysfunction, tissue fibrosis, and viral infection.

Overexpression of Human Syndecan-1 Protects against the Diethylnitrosamine-Induced Hepatocarcinogenesis in Mice

Simple Summary

Syndecan-1 is a Janus-faced proteoglycan: depending on the type of cancer, it can promote or inhibit the development of tumors. Our previous in vitro experiments revealed that transfection of human syndecan-1 (hSDC1) into hepatoma cells, initiating hepatocyte-like differentiation. To further confirm the antitumor action of hSDC1 in the context of liver carcinogenesis, mice transgenic for albumin promoter-driven hSDC1 were created with exclusive expression of hSDC1 in the liver. Indeed, hSDC1 interfered with the development of liver cancer in diethylnitrosamine (DEN)-induced hepatocarcinogenesis experiments. The mechanism was found to be related to lipid metabolism that plays an important role in the induction of nonalcoholic liver cirrhosis. Nonalcoholic fatty liver disease is known to promote the development of cancer; therefore, the oncoprotective effect of hSDC1 may be mediated by a beneficial modulation of lipid metabolism.

Abstract

Although syndecan-1 (SDC1) is known to be dysregulated in various cancer types, its implication in tumorigenesis is poorly understood. Its effect may be detrimental or protective depending on the type of cancer. Our previous data suggest that SDC1 is protective against hepatocarcinogenesis. To further verify this notion, human SDC1 transgenic (hSDC1^+/+) mice were generated that expressed hSDC1 specifically in the liver under the control of the albumin promoter. Hepatocarcinogenesis was induced by a single dose of diethylnitrosamine (DEN) at an age of 15 days after birth, which resulted in tumors without cirrhosis in wild-type and hSDC1^+/+ mice. At the experimental endpoint, livers were examined macroscopically and histologically, as well as by immunohistochemistry, Western blot, receptor tyrosine kinase array, phosphoprotein array, and proteomic analysis. Liver-specific overexpression of hSDC1 resulted in an approximately six month delay in tumor formation via the promotion of SDC1 shedding, downregulation of lipid metabolism, inhibition of the mTOR and the β-catenin pathways, and activation of the Foxo1 and p53 transcription factors that lead to the upregulation of the cell cycle inhibitors p21 and p27. Furthermore, both of them are implicated in the regulation of intermediary metabolism. Proteomic analysis showed enhanced lipid metabolism, activation of motor proteins, and loss of mitochondrial electron transport proteins as promoters of cancer in wild-type tumors, inhibited in the hSDC1^+/+ livers. These complex mechanisms mimic the characteristics of nonalcoholic steatohepatitis (NASH) induced human liver cancer successfully delayed by syndecan-1.

Genetic variants associated with expression of TCF19 contribute to the risk of head and neck cancer in Chinese population

BACKGROUND

Squamous cell carcinoma of the head and neck (SCCHN) is one of the most common cancers worldwide and includes cancers arising from the oral cavity, pharynx and larynx. Genome-wide association studies have found several genetic variants related to the risk of SCCHN; however, they could only explain a small fraction of the heritability. Thus, more susceptibility loci associated with SCCHN need to be identified.

METHODS

An association study was conducted by genotyping 555 patients with SCCHN and 1367 controls in a Chinese population. Single-variant association analysis was conducted on 63 373 SNPs, and the promising variants were then confirmed by a two-stage validation with 1875 SCCHN cases and 4637 controls. Bioinformatics analysis and functional assays were applied to uncover the potential pathogenic mechanism of the promising variants and genes associated with SCCHN.

RESULTS

We first identified three novel genetic variants significantly associated with the risk of SCCHN (p=7.45×10^-7 for rs2517611 at 6p22.1, p=1.76×10^-9 for rs2524182 at 6p21.33 and p=2.17×10^-10 for rs3131018 at 6p21.33). Further analysis and biochemical assays showed that rs3094187, which was in a region in high linkage disequilibrium with rs3131018, could modify TCF19 expression by regulating the binding affinity of the transcription factor SREBF1 to the promoter of TCF19. In addition, experiments revealed that the inhibition of TCF19 may affect several important pathways involved in tumourigenesis and attenuate the cell proliferation and migration of SCCHN.

CONCLUSION

These findings offer important evidence that functional genetic variants could contribute to development of SCCHN and that TCF19 may function as a putative susceptibility gene for SCCHN.

Elucidating the Consequences of Heparan Sulfate Binding by Heparanase 2

Unlike the intense research effort devoted to exploring the significance of heparanase in human diseases, very little attention was given to its close homolog, heparanase 2 (Hpa2). The emerging role of Hpa2 in a rare autosomal recessive congenital disease called urofacial syndrome (UFS), clearly indicates that Hpa2 is not a pseudogene but rather a gene coding for an important protein. Hpa2 lacks the heparan sulfate (HS)-degrading activity typical of heparanase, yet exhibits high affinity to HS, affinity that is 10-fold higher than that of heparanase. The consequences of this high-affinity interaction of Hpa2 with plasma membrane HSPG has not been explored yet. Here, we used highly purified Hpa2 protein to examine this aspect. We provide evidence that cells adhere to and spread on dishes coated with Hpa2. We also show that cell migration is attenuated markedly by exogenous addition of Hpa2 to primary and transformed cells, a function that agrees with the anti-cancer properties of Hpa2. Interestingly, we found that exogenous addition of Hpa2 also disrupts the morphology of cell colonies, resulting in cell scattering. This implies that under certain conditions and experimental settings, Hpa2 may exhibit pro-tumorigenic properties. We further developed a panel of anti-Hpa2 monoclonal antibodies (mAb) and show that these properties of Hpa2 are prevented by some of the newly-developed mAb, thus providing new molecular tools to better appreciate the significance of Hpa2 in health and disease.

Transcriptome profiling of different developmental stages of corpus luteum during the estrous cycle in pigs

To better understand the molecular basis of corpus luteum (CL) development and function RNA-Seq was utilized to identify differentially expressed genes (DEGs) in porcine CL during different physiological stages of the estrous cycle viz. early (EL), mid (ML), late (LL) and regressed (R) luteal. Stage wise comparisons obtained 717 (EL vs. ML), 568 (EL vs. LL), 527 (EL vs. R), 786 (ML vs. LL), 474 (ML vs. R) and 534 (LL vs. R) DEGs with log₂(FC) ≥1 and p < 0.05. The process of angiogenesis, steroidogenesis, signal transduction, translation, cell proliferation and tissue remodelling were significantly (p < 0.05) enriched in EL, ML and LL stages, where as apoptosis was most active in regressed stage. Pathway analysis revealed that most annotated genes were associated with lipid metabolism, translation, immune and endocrine system pathways depicting intra-luteal control of diverse CL function. The network analysis identified genes AR, FOS, CDKN1A, which were likely the novel hub genes regulating CL physiology.

Emerging Role of Syndecans in Extracellular Matrix Remodeling in Cancer

The extracellular matrix (ECM) offers a structural basis for regulating cell functions while also acting as a collection point for bioactive molecules and connective tissue cells. To perform pathological functions under a pathological condition, the involved cells need to regulate the ECM to support their altered functions. This is particularly common in the development of cancer. The ECM has been recognized as a key driver of cancer development and progression, and ECM remodeling occurs at all stages of cancer progression. Thus, cancer cells need to change the ECM to support relevant cell surface adhesion receptor-mediated cell functions. In this context, it is interesting to examine how cancer cells regulate ECM remodeling, which is critical to tumor malignancy and metastatic progression. Here, we review how the cell surface adhesion receptor, syndecan, regulates ECM remodeling as cancer progresses, and explore how this can help us better understand ECM remodeling under these pathological conditions.

Metal ions and the extracellular matrix in tumor migration

In this review, we explore the roles of divalent metal ions in structure and function within the extracellular matrix (ECM), specifically, their interaction with glycosaminoglycans (GAGs) during tumor progression. Metals and GAGs have been individually associated with physiological and pathological processes, however, their combined activities in regulating cell behavior and ECM remodeling have not been fully explored to date. During tumor progression, divalent metals and GAGs participate in central processes, such as cell migration and angiogenesis, either by modulating cell surface molecules, as well as soluble signaling factors. In addition, studies on metals and polysaccharides interactions have been of great value, as they provide structural information that can be correlated with function. Finally, we believe that understanding how metals are regulated in physiological and pathological conditions is paramount for the development of new treatment strategies, as well as diagnostic and exploratory tools.

Cumulus cell gene expression in luteal-phase-derived oocytes after double stimulation in one menstrual cycle

RESEARCH QUESTION

Does double stimulation (DuoStim) affect cumulus cell gene expression in luteal-phase-derived oocytes?

DESIGN

This prospective observational study included 39 patients with reduced ovarian reserve. Fifteen patients (group 1) underwent IVF with a gonadotrophin-releasing hormone antagonist in the follicular phase and 24 patients (group 2) underwent DuoStim. A total of 149 cumulus cell samples were divided into two groups according to the phase of the cycle: group 1 included 55 follicular-phase-derived oocytes and group 2 included 94 luteal-phase-derived oocytes. The expression levels of the following genes were assessed using quantitative polymerase chain reaction: HAS2, VCAN, ALCAM, PTGS2, GREM1, ITPKA, TRPM7, SDC4, CALM2, SPSB2, TP53I3, PGR and PFKP.

RESULTS

The expression of 10 out of 13 genes in cumulus cells was similar between DuoStim luteal-phase-derived oocytes and follicular-phase-derived oocytes. A significant increase in the mRNA levels of VCAN (15.542 ± 6.8 versus 20.353 ± 10.58; P = 0.001), SDC4 (1.016 ± 0.65 versus 1.318 ± 0.97; P = 0.013), and TP53I3 (0.185 ± 0.09 versus 0.270 ± 0.11; P = 1.19E-05) was observed in group 2. The number of oocytes collected (5.57 ± 2.3 versus 5.7 ± 2.7; P > 0.05) and the number of blastocysts were comparable between the groups (2.1 ± 2.1 versus 2.7 ± 2.2; P > 0.05).

CONCLUSIONS

The DuoStim approach leads to changes in the follicular environment. It affects the expression levels of VCAN, SDC4, and TP53I3 in the cumulus cells of luteal-phase-derived oocytes. These results, however, did not correlate with oocyte maturation, embryo quality and pregnancy rate.

The surface syndecan protein from Macrobrachium rosenbergii could function as mediator in bacterial infections

Due to the aquatic animal pathogens are numerous and specific, the pathogen invasion mechanisms are more complicated. The cell surface receptors play vital roles to understand these mechanisms. Syndecan is a cell surface protein and could function as a receptor involved bacteria and virus infections. But there are few studies on the function of syndecan in shrimp and their interaction with aquatic bacterial pathogens. In the present study, we identified a syndecan receptor gene from Macrobrachium rosenbergii and analyzed its functions during the bacterial infections. The MrSDC was expressed in various tissues and presented a constitutive expression distribution except in eyestalk. Recombinant MrSDC-his tag protein was expressed in the E. coli BL21 with pET30a/MrSDC plasmid and exhibited a broad bacterial binding activities. The inhibition of MrSDC expression by dsRNA interference and antibody blocked could significantly reduce the number of Aeromonas hydrophila in hepatopancreas compared with the control. The overexpression of MrSDC by mRNA injection could significantly increase the number of A. hydrophila. In addition, the functional role of syndecan heparan sulfate chains in bacterial recognition was also studied. After extra injection of heparan sulfate in vivo, the bacterial numbers and accumulative mortality of M. rosenbergii were significantly higher than control groups and exhibit a dose effect. All these data could indicate that the cell surface syndecan protein could function as mediator in bacterial infections by the heparan sulfate chains. Our present study will provide new insights into the functions of shrimp syndecan.

Similarities and Differences of Blood N-Glycoproteins in Five Solid Carcinomas at Localized Clinical Stage Analyzed by SWATH-MS

Cancer is mostly incurable when diagnosed at a metastatic stage, making its early detection via blood proteins of immense clinical interest. Proteomic changes in tumor tissue may lead to changes detectable in the protein composition of circulating blood plasma. Using a proteomic workflow combining N-glycosite enrichment and SWATH mass spectrometry, we generate a data resource of 284 blood samples derived from patients with different types of localized-stage carcinomas and from matched controls. We observe whether the changes in the patient's plasma are specific to a particular carcinoma or represent a generic signature of proteins modified uniformly in a common, systemic response to many cancers. A quantitative comparison of the resulting N-glycosite profiles discovers that proteins related to blood platelets are common to several cancers (e.g., THBS1), whereas others are highly cancer-type specific. Available proteomics data, including a SWATH library to study N-glycoproteins, will facilitate follow-up biomarker research into early cancer detection.

The Laminin-α1 Chain-Derived Peptide, AG73, Binds to Syndecans on MDA-231 Breast Cancer Cells and Alters Filopodium Formation

Breast cancer is one of the most common forms of cancer affecting women in the United States, second only to skin cancers. Although treatments have been developed to combat primary breast cancer, metastasis remains a leading cause of death. An early step of metastasis is cancer cell invasion through the basement membrane. However, this process is not yet well understood. AG73, a synthetic laminin-α1 chain peptide, plays an important role in cell adhesion and has previously been linked to migration, invasion, and metastasis. Thus, we aimed to identify the binding partner of AG73 on breast cancer cells that could mediate cancer progression. We performed adhesion assays using MCF10A, T47D, SUM1315, and MDA-231 breast cell lines and found that AG73 binds to syndecans (Sdcs) 1, 2, and 4. This interaction was inhibited when we silenced Sdcs 1 and/or 4 in MDA-231 cells, indicating the importance of these receptors in this relationship. Through actin staining, we found that silencing of Sdc 1, 2, and 4 expression in MDA-231 cells exhibits a decrease in the length and number of filopodia bound to AG73. Expression of mouse Sdcs 1, 2, and 4 in MDA-231 cells provides rescue in filopodia, and overexpression of Sdcs 1 and 2 leads to increased filopodium length and number. Our findings demonstrate an intrinsic interaction between AG73 in the tumor environment and the Sdcs on breast cancer cells in supporting tumor cell adhesion and invasion through filopodia, an important step in cancer metastasis.

N-terminal syndecan-2 domain selectively enhances 6-O heparan sulfate chains sulfation and promotes VEGFA165-dependent neovascularization

The proteoglycan Syndecan-2 (Sdc2) has been implicated in regulation of cytoskeleton organization, integrin signaling and developmental angiogenesis in zebrafish. Here we report that mice with global and inducible endothelial-specific deletion of Sdc2 display marked angiogenic and arteriogenic defects and impaired VEGFA165 signaling. No such abnormalities are observed in mice with deletion of the closely related Syndecan-4 (Sdc4) gene. These differences are due to a significantly higher 6-O sulfation level in Sdc2 versus Sdc4 heparan sulfate (HS) chains, leading to an increase in VEGFA165 binding sites and formation of a ternary Sdc2-VEGFA165-VEGFR2 complex which enhances VEGFR2 activation. The increased Sdc2 HS chains 6-O sulfation is driven by a specific N-terminal domain sequence; the insertion of this sequence in Sdc4 N-terminal domain increases 6-O sulfation of its HS chains and promotes Sdc2-VEGFA165-VEGFR2 complex formation. This demonstrates the existence of core protein-determined HS sulfation patterns that regulate specific biological activities.

Vascular Endothelial Cell Behavior in Complex Mechanical Microenvironments

The vascular mechanical microenvironment consists of a mixture of spatially and temporally changing mechanical forces. This exposes vascular endothelial cells to both hemodynamic forces (fluid flow, cyclic stretching, lateral pressure) and vessel forces (basement membrane mechanical and topographical properties). The vascular mechanical microenvironment is "complex" because these forces are dynamic and interrelated. Endothelial cells sense these forces through mechanosensory structures and transduce them into functional responses via mechanotransduction pathways, culminating in behavior directly affecting vascular health. Recent in vitro studies have shown that endothelial cells respond in nuanced and unique ways to combinations of hemodynamic and vessel forces as compared to any single mechanical force. Understanding the interactive effects of the complex mechanical microenvironment on vascular endothelial behavior offers the opportunity to design future biomaterials and biomedical devices from the bottom-up by engineering for the cellular response. This review describes and defines (1) the blood vessel structure, (2) the complex mechanical microenvironment of the vascular endothelium, (3) the process in which vascular endothelial cells sense mechanical forces, and (4) the effect of mechanical forces on vascular endothelial cells with specific attention to recent works investigating the influence of combinations of mechanical forces. We conclude this review by providing our perspective on how the field can move forward to elucidate the effects of the complex mechanical microenvironment on vascular endothelial cell behavior.

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.

The transcriptional factor ZEB1 represses Syndecan 1 expression in prostate cancer

Syndecan 1 (SDC-1) is a cell surface proteoglycan with a significant role in cell adhesion, maintaining epithelial integrity. SDC1 expression is inversely related to aggressiveness in prostate cancer (PCa). During epithelial to mesenchymal transition (EMT), loss of epithelial markers is mediated by transcriptional repressors such as SNAIL, SLUG, or ZEB1/2 that bind to E-box promoter sequences of specific genes. The effect of these repressors on SDC-1 expression remains unknown. Here, we demonstrated that SNAIL, SLUG and ZEB1 expressions are increased in advanced PCa, contrarily to SDC-1. SNAIL, SLUG and ZEB1 also showed an inversion to SDC-1 in prostate cell lines. ZEB1, but not SNAIL or SLUG, represses SDC-1 as demonstrated by experiments of ectopic expression in epithelial prostate cell lines. Inversely, expression of ZEB1 shRNA in PCa cell line increased SDC-1 expression. The effect of ZEB1 is transcriptional since ectopic expression of this gene represses SDC-1 promoter activity and ZEB1 binds to the SDC-1 promoter as detected by ChIP assays. An epigenetic mark associated to transcription repression H3K27me3 was bound to the same sites that ZEB1. In conclusion, this study identifies ZEB1 as a key repressor of SDC-1 during PCa progression and point to ZEB1 as a potentially diagnostic marker for PCa.

Comparison of Syndecan-1 Immunohistochemical Expression in Lobular and Ductal Breast Carcinoma with Nodal Metastases

Syndecan-1 (Sdc1) is a transmembrane heparan sulfate proteoglycan, an extracellular matrix receptor involved in intercellular communication, proliferation, angiogenesis, and metastasis. This study determined and compared Sdc1 expression in the tumor cells and stroma of 30 invasive lobular and 30 invasive ductal breast carcinomas (ILCs/IDCs), also in the axillary node metastases of ductal type, and correlated it with clinical and tumor parameters. Sdc1 was expressed in the epithelium of 90% carcinoma of both histological types. Also, it was most frequently expressed in their tumor stroma, but in ILC, stromal expression was negative in 40%. Sdc1 was expressed in 86.7% of the metastatic epithelium of IDC nodal metastases (in even 50% as high expression), while the nodal stroma was negative in 46.7%. Primary IDC showed a negative correlation between epithelial Sdc1 and progesterone receptors (PRs), whereas ILC showed a positive correlation between stromal Sdc1 and histological gradus. In the metastatic epithelium, Sdc1 was negatively correlated with a patient's age, estrogen receptors (ERs), and PRs in the primary tumors, while the stroma of metastases demonstrated a positive correlation with the focus number in primary tumors and a negative correlation with PRs in primary tumors. This research revealed identical overall epithelial Sdc1 expression in both breast carcinomas with no statistically significant difference in its stromal expression and confirmed the role of Sdc1 in the progression of both tumor types and in the development of ductal carcinoma's metastatic potential.

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.

Processing of syndecan-2 by matrix metalloproteinase-14 and effect of its cleavage on VEGF-induced tube formation of HUVECs

Syndecans (SDCs) are transmembrane proteoglycans that are involved in cell adhesion and cell communication. Specifically, SDC2 plays a key role in tumorigenesis, metastasis, and angiogenesis. Previously, we found that rat SDC2 is shed by matrix metalloproteinase-7 (MMP-7) in colon cancer cells. Here, we analyzed the susceptibility of rat SDC2 to various MMPs. We found that the rat SDC2 ectodomain (ECD) fused to the C-terminal Fc region, which was expressed in mammalian cells, was cleaved more efficiently by MMP-14 than MMP-7. Likewise, when anchored on the surface of HeLa cells, rat SDC2 was cleaved more efficiently by the treatment of MMP-14 than MMP-7 and was shed more readily by membrane-anchored MMP-14 than soluble MMP-14. Furthermore, MMP-14 cleaved recombinant SDC2-ECD expressed in Escherichia coli into multiple fragments. Using N-terminal amino acid sequencing and the top-down proteomics approach, we determined that the major cleavage sites were S⁸⁸↓L⁸⁹, T⁹⁸↓M⁹⁹, T¹⁰⁰↓L¹⁰¹, D¹³²↓P¹³³, and N¹⁴⁸↓L¹⁴⁹ for rat SDC2-ECD and S⁵⁵↓G⁵⁶, S⁶⁵↓P⁶⁶, P⁷⁵↓K⁷⁶, N⁹²↓I⁹³ D¹²²↓P¹²³, and S¹³⁸↓L¹³⁹ for human SDC2-ECD. Finally, the rat and human SDC2-ECD lost the ability to suppress vascular endothelial growth factor-induced formation of capillary-like tubes by human umbilical vein endothelial cells following cleavage by MMP-14, but its major cleavage-site mutant of rat SDC2-ECD did not. These results suggest that MMP-14 is a novel enzyme responsible for degrading SDC2 and impairing its physiological roles including angiogenesis.

Immunohistochemical Expression Profiles of Cell Adhesion Molecules, Matrix Metalloproteinases and their Tissue Inhibitors in Central and Peripheral Neoplastic Foci of Feline Mammary Carcinoma

Feline mammary carcinoma (FMC) is a common cancer with high metastatic potential and high mortality rate. Loss of cell-cell interactions and degradation of the extracellular matrix by proteinases enhances tumour invasion and metastasis. Peripheral neoplastic foci (PNF) are defined as the presence of discrete tumour cell clusters, splitting off from central neoplastic foci (CNF) and lodging around these CNF. PNF therefore locate at the tumour-host interface at the site of invasion. The aim of this study was to evaluate immunohistochemically the expression of cell adhesion molecules (e-cadherin [CDH-1], syndecan 1 [SDC-1] and nectin-2), matrix metalloproteinases (matrix metalloproteinase [MMP]-2, MMP-7 and MMP-9) and their tissue inhibitors (tissue inhibitor of matrix metalloproteinase [TIMP]-1 and TIMP-2) together with the cellular proliferation marker, Ki67, in CNF and PNF of FMCs of different clinical stages and histological grades. Compared with control sections from areas of mammary gland hyperplasia, lower expression of MMP-7 and TIMP-2 was observed in all stages. Increased expression of TIMP-1 was observed in PNF in early-stage disease with no metastasis, while marked expression of CDH-1 and Ki67 occurred in late-stage FMC. In addition, the expression of MMP-2, MMP-9 and TIMP-1 in PNF of tumours with high histological grade (grade III) was higher than in low-grade tumours. The observed divergent protein expression in PNF could potentially form the basis of acting as novel markers in FMC. Potential markers may include the expression of TIMP-1 in PNF in early stage lesions, the expression of CDH-1 and Ki67 in late stages and the expression of MMP-2, MMP-9 and TIMP-1 in high-grade tumours.

Cell Adhesion Molecule CD166/ALCAM Functions Within the Crypt to Orchestrate Murine Intestinal Stem Cell Homeostasis

BACKGROUND & AIMS

Intestinal epithelial homeostasis is maintained by active-cycling and slow-cycling stem cells confined within an instructive crypt-based niche. Exquisite regulating of these stem cell populations along the proliferation-to-differentiation axis maintains a homeostatic balance to prevent hyperproliferation and cancer. Although recent studies focus on how secreted ligands from mesenchymal and epithelial populations regulate intestinal stem cells (ISCs), it remains unclear what role cell adhesion plays in shaping the regulatory niche. Previously we have shown that the cell adhesion molecule and cancer stem cell marker, CD166/ALCAM (activated leukocyte cell adhesion molecule), is highly expressed by both active-cycling Lgr5⁺ ISCs and adjacent Paneth cells within the crypt base, supporting the hypothesis that CD166 functions to mediate ISC maintenance and signal coordination.

METHODS

Here we tested this hypothesis by analyzing a CD166^-/- mouse combined with immunohistochemical, flow cytometry, gene expression, and enteroid culture.

RESULTS

We found that animals lacking CD166 expression harbored fewer active-cycling Lgr5⁺ ISCs. Homeostasis was maintained by expansion of the transit-amplifying compartment and not by slow-cycling Bmi1⁺ ISC stimulation. Loss of active-cycling ISCs was coupled with deregulated Paneth cell homeostasis, manifested as increased numbers of immature Paneth progenitors due to decreased terminal differentiation, linked to defective Wnt signaling. CD166^-/- Paneth cells expressed reduced Wnt3 ligand expression and depleted nuclear β-catenin.

CONCLUSIONS

These data support a function for CD166 as an important cell adhesion molecule that shapes the signaling microenvironment by mediating ISC-niche cell interactions. Furthermore, loss of CD166 expression results in decreased ISC and Paneth cell homeostasis and an altered Wnt microenvironment.

Coupling of vinculin to F-actin demands Syndecan-4 proteoglycan

Syndecans are heparan sulfate proteoglycans characterized as transmembrane receptors that act cooperatively with the cell surface and extracellular matrix proteins. Syn4 knockdown was performed in order to address its role in endothelial cells (EC) behavior. Normal EC and shRNA-Syn4-EC cells were studied comparatively using complementary confocal, super-resolution and non-linear microscopic techniques. Confocal and super-resolution microscopy revealed that Syn4 knockdown alters the level and arrangement of essential proteins for focal adhesion, evidenced by the decoupling of vinculin from F-actin filaments. Furthermore, Syn4 knockdown alters the actin network leading to filopodial protrusions connected by VE-cadherin-rich junction. shRNA-Syn4-EC showed reduced adhesion and increased migration. Also, Syn4 silencing alters cell cycle as well as cell proliferation. Moreover, the ability of EC to form tube-like structures in matrigel is reduced when Syn4 is silenced. Together, the results suggest a mechanism in which Syndecan-4 acts as a central mediator that bridges fibronectin, integrin and intracellular components (actin and vinculin) and once silenced, the cytoskeleton protein network is disrupted. Ultimately, the results highlight Syn4 relevance for balanced cell behavior.

The molecular mechanism by which saturated lysophosphatidylcholine attenuates the metastatic capacity of melanoma cells

Lysophophatidylcholine (LysoPC) is an abundant constituent in human plasma. Patients with malignant cancer diseases have attenuated LysoPC plasma levels, and thus LysoPC has been examined as a metabolic biomarker for cancer prediction. Preclinical studies have shown that solid tumor cells drastically degrade LysoPCs by incorporating their free fatty acids into cell membrane phospholipids. In this way, LysoPC C18:0 reduced the metastatic spread of murine melanoma B16.F10 cells in mice. Although membrane rigidification may have a key role in the attenuation of metastasis, evidence for this has yet to be shown. Therefore, the present study aimed to determine how LysoPC reduces the metastatic capacity of B16.F10 cells. Following cellular preincubation with LysoPC C18:0 at increasing concentrations and lengths of time, cell migration was most significantly attenuated with 450 μm LysoPC C18:0 at 72 h. Biosensor measurements suggest that, despite their abundance in B16.F10 cells, LysoPC‐sensitive G protein‐coupled receptors do not appear to contribute to this effect. Instead, the attenuated migration appears to result from changes in cell membrane properties and their effect on underlying signaling pathways, most likely the formation of focal adhesion complexes. Treatment with 450 μm LysoPC C18:0 activates protein kinase C (PKC)δ to phosphorylate syndecan‐4, accompanied by deactivation of PKCα. Subsequently, focal adhesion complex formation was attenuated, as confirmed by the reduced activity of focal adhesion kinase (FAK). Interestingly, 450 μm LysoPC C18:1 did not affect FAK activity, explaining its lower propensity to affect migration and metastasis. Therefore, membrane rigidification by LysoPC C18:0 appears to prevent the formation of focal adhesion complexes, thus affecting integrin activity as a key for metastatic melanoma spread.

A comparative study of syndecan-1 expression in different odontogenic tumors

BACKGROUND

Expression of various cellular/molecular factors change during the course of tumor formation from odontogenic tissues of the tooth germ. Evaluation of these factors can help provide a better perception of the tumorigenesis and biologic behavior of odontogenic tumors (OTs). Syndecan-1 is a heparan sulfate proteoglycan which has not been extensively investigated in these lesions. The objective of the present study was to assess the immunohistochemical expression of CD138 in adenomatoid odontogenic tumor (AOT), ameloblastic fibroma (AF) and odontogenic myxoma (OM) and to compare it with ameloblastoma and keratocystic odontogenic tumor (KCOT).

METHOD

A total of 58 OTs consisting of 7 AOTs, 5 OMs, 7 AFs, 29 KCOTs and 10 ameloblastomas were immunohistochemically stained with monoclonal antibody against syndecan-1 and the percentage and intensity of the immunostained cells was assessed. Kruskal-Wallis test followed by Bonferroni analysis was used for comparisons (P < 0.05).

RESULTS

Syndecan-1 was expressed in all samples except for OMs. Both percentage and intensity of syndecan-1 expression were statistically different among the studied OTs (P < 0.001). Pairwise comparisons showed significant difference only between OMs and each of the other tumors.

CONCLUSION

Syndecan-1 may be involved in the pathogenesis of AOT, AF, KCOT and ameloblastoma. However, considering the different behaviors of these tumors along with their similar expression of syndecan-1, it seems that its effect on clinical aggressiveness is limited. The significance of negative immunoexpression of this protein in OM requires further investigation.

Lapatinib resistance in HER2+ cancers: latest findings and new concepts on molecular mechanisms

In the era of new and mostly effective molecular targeted therapies, human epidermal growth factor receptor 2 positive (HER2+) cancers are still intractable diseases. Lapatinib, a dual epidermal growth factor receptor (EGFR) and HER2 tyrosine kinase inhibitor, has greatly improved breast cancer prognosis in recent years after the initial introduction of trastuzumab (Herceptin). However, clinical evidence indicates the existence of both primary unresponsiveness and secondary lapatinib resistance, which leads to the failure of this agent in HER2+ cancer patients. It remains a major clinical challenge to target the oncogenic pathways with drugs having low resistance. Multiple pathways are involved in the occurrence of lapatinib resistance, including the pathways of receptor tyrosine kinase, non-receptor tyrosine kinase, autophagy, apoptosis, microRNA, cancer stem cell, tumor metabolism, cell cycle, and heat shock protein. Moreover, understanding the relationship among these mechanisms may contribute to future tumor combination therapies. Therefore, it is of urgent necessity to elucidate the precise mechanisms of lapatinib resistance and improve the therapeutic use of this agent in clinic. The present review, in the hope of providing further scientific support for molecular targeted therapies in HER2+ cancers, discusses about the latest findings and new concepts on molecular mechanisms underlying lapatinib resistance.

Heparanase: From basic research to therapeutic applications in cancer and inflammation

Heparanase, the sole heparan sulfate degrading endoglycosidase, regulates multiple biological activities that enhance tumor growth, angiogenesis and metastasis. Heparanase expression is enhanced in almost all cancers examined including various carcinomas, sarcomas and hematological malignancies. Numerous clinical association studies have consistently demonstrated that upregulation of heparanase expression correlates with increased tumor size, tumor angiogenesis, enhanced metastasis and poor prognosis. In contrast, knockdown of heparanase or treatments of tumor-bearing mice with heparanase-inhibiting compounds, markedly attenuate tumor progression further underscoring the potential of anti-heparanase therapy for multiple types of cancer. Heparanase neutralizing monoclonal antibodies block myeloma and lymphoma tumor growth and dissemination; this is attributable to a combined effect on the tumor cells and/or cells of the tumor microenvironment. In fact, much of the impact of heparanase on tumor progression is related to its function in mediating tumor-host crosstalk, priming the tumor microenvironment to better support tumor growth, metastasis and chemoresistance. The repertoire of the physio-pathological activities of heparanase is expanding. Specifically, heparanase regulates gene expression, activates cells of the innate immune system, promotes the formation of exosomes and autophagosomes, and stimulates signal transduction pathways via enzymatic and non-enzymatic activities. These effects dynamically impact multiple regulatory pathways that together drive inflammatory responses, tumor survival, growth, dissemination and drug resistance; but in the same time, may fulfill some normal functions associated, for example, with vesicular traffic, lysosomal-based secretion, stress response, and heparan sulfate turnover. Heparanase is upregulated in response to chemotherapy in cancer patients and the surviving cells acquire chemoresistance, attributed, at least in part, to autophagy. Consequently, heparanase inhibitors used in tandem with chemotherapeutic drugs overcome initial chemoresistance, providing a strong rationale for applying anti-heparanase therapy in combination with conventional anti-cancer drugs. Heparin-like compounds that inhibit heparanase activity are being evaluated in clinical trials for various types of cancer. Heparanase neutralizing monoclonal antibodies are being evaluated in pre-clinical studies, and heparanase-inhibiting small molecules are being developed based on the recently resolved crystal structure of the heparanase protein. Collectively, the emerging premise is that heparanase expressed by tumor cells, innate immune cells, activated endothelial cells as well as other cells of the tumor microenvironment is a master regulator of the aggressive phenotype of cancer, an important contributor to the poor outcome of cancer patients and a prime target for therapy.

Potential signaling pathway involved in sphingosine-1-phosphate-induced epithelial-mesenchymal transition in cancer

The developmental process of epithelial-mesenchymal transition (EMT) occurs when epithelial cells acquire invasive mesenchymal cell characteristics, and the activation of this process has been indicated to be involved in tumor progression. EMT could be induced by growth factors, cytokines and matrix metalloproteinases (MMPs). sphingosine-1-phosphate (S1P) is a biologically-active lipid that plays an important role in cancer metastasis. S1P also contributes to the activation of EMT. However, the mechanism underlying S1P-induced EMT is unclear. Increased evidence has demonstrated that the cell surface glycocalyx is closed associated with S1P and plays an important role in tumor progression, suggesting that S1P-induced EMT could be Snail-MMP signaling-dependent. Thus, we hypothesize that an S1P-glycocalyx-Snail-MMP signaling axis mediates S1P-induced EMT. This is an essential step towards improved understanding of the underlying mechanism involved in S1P-regulted EMT, and the development of novel diagnostic and anticancer therapeutic strategies.

Production and characterization of monoclonal antibodies specific for canine CD138 (syndecan-1) for nuclear medicine preclinical trials on spontaneous tumours

We isolated 11 antibodies specific for canine CD138 (cCD138) to validate the interest of CD138 antigen targeting in dogs with spontaneous mammary carcinoma. The affinity of the monoclonal antibodies in the nanomolar range is suitable for immunohistochemistry and nuclear medicine applications. Four distinct epitopes were recognized on cCD138 by this panel of antibodies. CD138 expression in canine healthy tissues is comparable to that reported in humans. CD138 is frequently expressed in canine mammary carcinomas corresponding to the human triple negative breast cancer subtype, with cytoplasmic and membranous expression. In canine diffuse large B-cell lymphoma, CD138 expression is associated with the 'non-germinal center' phenotype corresponding to the most aggressive subtype in humans. This homology of CD138 expression between dogs and humans confirms the relevance of tumour-bearing dogs as spontaneous models for nuclear medicine applications, especially for the evaluation of new tumour targeting strategies for diagnosis by phenotypic imaging and radio-immunotherapy.

Anti-human CD138 monoclonal antibodies and their bispecific formats: generation and characterization

Syndecan-1 (CD138), a heparan sulfate proteoglycan, acts as a co-receptor for growth factors and chemokines and is a molecular marker associated with the epithelial-mesenchymal transition during development and carcinogenesis. In this study, we generated two specific mouse anti-human CD138 monoclonal antibodies (mAbs, clone ID: 480CT5.4.3, 587CT7.3.6.5) using hybridoma technology and identified their immunological characteristics. After hybridoma sequencing, the single-chain variable fragments (ScFvs) cloned from two hybridoma cells were combined with anti-CD3 OKT-3 ScFv to generate two recombinant bispecific antibodies (h-STL002, m-STL002) against CD138 and CD3 molecules, respectively. The bispecific antibodies were able to specifically target CD138 + multiple myeloma (MM) cells and CD3 + T cells, and showed the potent cytotoxicity against MM RPMI-8226 cell line through T cell activation. However, these bispecific antibodies without T cells did not cause toxic side effect on MM cells. Overall, the two hybridoma clones and their bispecific formats have great potential to promote diagnosis and immunotherapy of plasma cell malignancy.

The heparan sulfate mimetic PG545 interferes with Wnt/β-catenin signaling and significantly suppresses pancreatic tumorigenesis alone and in combination with gemcitabine

The heparan sulfate mimetic PG545 has been shown to exert anti-angiogenic and anti-metastatic activity in vitro and in vivo cancer models. Although much of this activity has been attributed to inhibition of heparanase and heparan sulfate-binding growth factors, it was hypothesized that PG545 may additionally disrupt Wnt signaling, an important pathway underlying the malignancy of pancreatic cancer. We show that PG545, by directly interacting with Wnt3a and Wnt7a, inhibits Wnt/β-catenin signaling leading to inhibition of proliferation in pancreatic tumor cell lines. Additionally, we demonstrate for the first time that the combination of PG545 with gemcitabine has strong synergistic effects on viability, motility and apoptosis induction in several pancreatic cell lines. In an orthotopic xenograft mouse model, combination of PG545 with gemcitabine efficiently inhibited tumor growth and metastasis compared to single treatment alone. Also, PG545 treatment alone decreased the levels of β-catenin and its downstream targets, cyclin D1, MMP-7 and VEGF which is consistent with our in vitro data. Collectively, our findings suggest that PG545 exerts anti-tumor activity by disrupting Wnt/β-catenin signaling and combination with gemcitabine should be considered as a novel therapeutic strategy for pancreatic cancer treatment.

Heparanase-induced shedding of syndecan-1/CD138 in myeloma and endothelial cells activates VEGFR2 and an invasive phenotype: prevention by novel synstatins

Multiple myeloma arises when malignant plasma cells invade and form multiple tumors in the bone marrow. High levels of heparanase (HPSE) correlate with poor prognosis in myeloma patients. A likely target of the enzyme is the heparan sulfate (HS) proteoglycan syndecan-1 (Sdc1, CD138), which is highly expressed on myeloma cells and contributes to poor prognosis in this disease. We find that HPSE promotes an invasive phenotype mediated by the very late antigen-4 (VLA-4, or α4β1 integrin) in myeloma cells plated on either fibronectin (FN) or vascular endothelial cell adhesion molecule-1 (VCAM-1), ligands that are prevalent in the bone marrow. The phenotype depends on vascular endothelial cell growth factor receptor-2 (VEGFR2), which is aberrantly expressed in myeloma, and is characterized by a highly protrusive lamellipodium and cell invasion. HPSE-mediated trimming of the HS on Sdc1 and subsequent matrix metalloproteinase-9-mediated shedding of the syndecan exposes a juxtamembrane site in Sdc1 that binds VEGFR2 and VLA-4, thereby coupling VEGFR2 to the integrin. Shed Sdc1 can be mimicked by recombinant Sdc1 ectodomain or by a peptide based on its binding motif, which causes VLA-4 to re-orient from the lagging edge (uropod) to the leading edge of migrating cells, couple with and activate VEGFR2. Peptides (called 'synstatins') containing only the VLA-4 or VEGFR2 binding sites competitively inhibit invasion, as they block coupling of the receptors. This mechanism is also utilized by vascular endothelial cells, in which it is also activated by HPSE, during endothelial cell tube formation. Collectively, our findings reveal for the first time the mechanism through which HPSE modulates Sdc1 function to promote both tumor cell invasion and angiogenesis, thereby driving multiple myeloma progression. The inhibitory synstatins, or inhibitors of HPSE enzyme activity, are likely to show promise as therapeutics against myeloma extravasation and spread.

Syndecan-1-Induced ECM Fiber Alignment Requires Integrin αvβ3 and Syndecan-1 Ectodomain and Heparan Sulfate Chains

Expression of the cell surface proteoglycan syndecan-1 (Sdc1) is frequently induced in stromal fibroblasts of invasive breast carcinomas. We have recently identified a correlation between stromal Sdc1 expression and extracellular matrix (ECM) fiber alignment, both in vitro and in vivo. ECMs derived from Sdc1-positive human mammary fibroblasts (HMF) showed an aligned fiber architecture, which contrasted markedly with the more random fiber arrangement in the ECM produced by Sdc1-negative HMFs. We further demonstrated that aligned fiber architecture promotes the directional migration and invasion of breast carcinoma cells. To decipher the molecular mechanisms governing the formation of an aligned, invasion-permissive ECM, a series of Sdc1 mutants was introduced into HMF. We found that both the ectodomain and heparan sulfate chains of Sdc1 were required for full activity of Sdc1 in regulating ECM alignment, while transmembrane and cytoplasmic domains were dispensable. Sdc1 regulates the activities of several integrins via its ectodomain. Integrins are key players in the assembly of fibronectin-rich ECM. In addition, integrins are capable of regulating cell morphology and cell shape and orientation may affect ECM architecture. Therefore, we investigated the role of integrins in Sdc1-mediated ECM fiber alignment. Sdc1-overexpressing HMF gained an enhanced spindle-shaped morphology when cultured in an overconfluent state under conditions permissive for ECM production, which was partially reversed by siRNA-mediated silencing of β3 integrin expression. Moreover, suppression of αvβ3 integrin activity by a function-blocking antibody or β3 knockdown largely abolished the aligned ECM fiber architecture and consequently the invasion-permissive properties of the ECM induced by Sdc1. The results suggest that Sdc1 may modulate fibronectin fibrillogenesis and/or alter cell morphology during ECM production through αvβ3 integrin, thereby mediating ECM fiber alignment. Understanding the mechanisms governing ECM organization may lead to the development of novel stroma-targeted therapy for breast cancer, aiming at converting an invasion-permissive to an invasion-restrictive microenvironment.