Role Of Cell Surface Proteoglycans Research Articles

The microRNA-cell surface proteoglycan axis in cancer progression.

Proteoglycans consist one of the major extracellular matrix class of biomolecules that demonstrate nodal roles in cancer progression. Modern diagnostic and therapeutic approaches include proteoglycan detection and pharmacological targeting in various cancer types. Proteoglycans orchestrate critical signaling pathways for cancer development and progression through dynamic interactions with matrix components. It is well established that the epigenetic signatures of cancer cells play critical role in guiding their functional properties and metastatic potential. Secreted microRNAs (miRNAs) reside in a complex network with matrix proteoglycans, thus affecting cell-cell and cell-matrix communication. This mini-review aims to highlight current knowledge on the cell-surface proteoglycan-mediated signaling cascades that regulate miRNA biogenesis in cancer. Moreover, the miRNA-mediated proteoglycan regulation during cancer progression and mechanistic aspects on the way that proteoglycans affect miRNA expression are presented. Recent advances on the role of cell surface proteoglycans in exosome biogenesis and miRNA packaging and expression are also discussed.

Role of cell surface proteoglycans in cancer immunotherapy.

Over the past few decades, understanding how tumor cells evade the immune system and their communication with their tumor microenvironment, has been the subject of intense investigation, with the aim of developing new cancer immunotherapies. The current therapies against cancer such as monoclonal antibodies against checkpoint inhibitors, adoptive T-cell transfer, cytokines, vaccines, and oncolytic viruses have managed to improve the clinical outcome of the patients. However, in some tumor entities, the response is limited and could benefit from the identification of novel therapeutic targets. It is known that tumor-extracellular matrix interplay and matrix remodeling are necessary for anti-tumor and pro-tumoral immune responses. Proteoglycans are dominant components of the extracellular matrix and are a highly heterogeneous group of proteins characterized by the covalent attachment of a specific linear carbohydrate chain of the glycosaminoglycan type. At cell surfaces, these molecules modulate the expression and activity of cytokines, chemokines, growth factors, adhesion molecules, and function as signaling co-receptors. By these mechanisms, proteoglycans influence the behavior of cancer cells and their microenvironment during the progression of solid tumors and hematopoietic malignancies. In this review, we discuss why cell surface proteoglycans are attractive pharmacological targets in cancer, and we present current and recent developments in cancer immunology and immunotherapy utilizing proteoglycan-targeted strategies.

ChemInform Abstract: Nervous Tissue Proteoglycans

The structure, biosynthesis, localization, and possible functional roles of nervous tissue glycosaminoglycans and proteoglycans were last reviewed several years ago70,74. Since that time, there has been an exponential increase in publications on the neurobiology of proteoglycans. This review will therefore focus on reports which have appeared in the period after 1988, and especially on those concerning the properties of individual characterized nervous tissue proteoglycans. Related areas such as the regulation of glycosaminoglycan biosynthesis and the roles of cell surface proteoglycans in adhesion and growth control are covered in other contributions to this special topic issue.

The Role of Syndecan‐1 in Arterial Mechanotransduction

Hemodynamic forces induced by blood flow are potent regulators of vascular homeostasis and arterial structure. While previous work has focused on the role of integrin receptors in mechanotransduction, little is known about the role of cell surface proteoglycans in these processes. This work focuses specifically on the role of the cell surface heparan sulfate proteoglycan syndecan‐1 in vascular cell mechanotransduction. We isolated vascular smooth muscle cells from syndecan‐1 knockout mice and tranfected them with wild‐type and mutated forms of syndecan‐1 using lentiviral vectors. Wild‐type, syndecan‐1 knockout and mutated syndecan‐1 overexpressing mouse vascular smooth muscle cells were cultured in plates with collagen coated silicone membranes. The cells were then subjected to 10% strain at 1 Hz biaxial or uniaxial loads for up to two hours. We found that syndecan‐1 knockout or deletion of the cytoplasmic region of syndecan‐1 caused an increase in actin stress fibers and focal adhesion sites in response to mechanical strain. Further, knockout of syndecan‐1 led to enhanced ERK and Src phosphorylation in response to mechanical strain. These findings support that syndecan‐1 is an important mediator of mechanotransduction in vascular cells.

Invasion of interstitial matrix by a novel cell line from primary peritoneal carcinosarcoma, and by established ovarian carcinoma cell lines: role of cell–matrix adhesion molecules, proteinases, and E-cadherin expression

Objective Primary peritoneal carcinosarcomas are similar to ovarian carcinomas in that they can metastasize by intraperitoneal dissemination; therefore, invasion of the submesothelial interstitial (stromal) matrix is an integral part of the pathology. Our objective was to study cell–matrix interactions that may influence invasive behavior of a novel, primary peritoneal carcinosarcoma cell line (PC880), and to assess how these cell–matrix interactions are different from frequently studied cultured ovarian carcinoma cells NIH:OVCAR-3, SKOV-3, and ES-2. We also wanted to determine how the expression of the cell–cell adhesion molecule E-cadherin is related to invasive behavior. Methods The PC880 cell line was established from ascites fluid of a patient diagnosed with primary peritoneal carcinosarcoma. Adhesion assays were done in titer plates coated with individual matrix components. Cell migration in monolayer cultures was assessed by the scratch wound assay method. Invasion assays were done using a three-dimensional type I collagen gel. Cytokeratin, vimentin, and E-cadherin were detected by Western blotting. E-cadherin mRNA was detected by RT-PCR. Results PC880 cells adhered well to fibronectin, laminin, and vitronectin in an integrin-dependent manner. The cells also adhered to type I collagen and invaded a three-dimensional type I collagen matrix. The invasiveness of the PC880 cells was moderated by pretreatment of the collagen matrix with heparin or chondroitin sulfate (82 and 63% of control invasiveness, respectively), indicating a role of cell surface proteoglycans in promoting invasive phenotype. Treatment of PC880 cells with sodium chlorate also decreased invasiveness (80% of control), further confirming the role of cell surface proteoglycans. Treatment of PC880 cells with function-blocking antibody to α2 integrin decreased invasiveness (57% of control), indicating the role of integrins in promoting the invasive phenotype. The protease inhibitors GM6001, E-64, and AEBSF decreased invasiveness (35, 57, and 37% of control, respectively) of PC880 cells. The ES-2 cells also adhered to type I collagen, and invaded the three-dimensional type I collagen matrix; however, inhibitors such as heparin, chondroitin sulfate, function-blocking antibody to α2 integrin, E-64, and AEBSF were less effective in moderating the invasiveness. Inhibition of invasiveness with sodium chlorate was the same as in PC880 cell, while GM6001 did not inhibit invasiveness at all. The NIH:OVCAR-3 and SK-OV-3 cells were previously found to adhere to type I collagen, but these cells did not invade the three-dimensional type I collagen matrix. In a monolayer culture PC880 and ES-2 cells had significantly higher motility than NIH:OVCAR-3 and SK-OV-3 cells. Only these noninvasive cell lines expressed E-cadherin protein or mRNA. Conclusions PC880 is the first cell line established from primary peritoneal carcinosarcoma, and the cytoskeletal composition indicated that these cells represent the sarcomatous elements of the tumor. PC880 cells, similar to ES-2 cells, adhered to type I collagen, and invaded a three-dimensional collagen matrix. The invasion of the interstitial matrix by both the peritoneal carcinosarcoma and the ovarian carcinoma cell line was mediated by cell surface proteoglycans, α2 integrin, and proteases. The invasive cell behavior of PC880 and ES-2 cells correlated with a high degree of motility, and with the lack of expression of the cell–cell adhesion molecule E-cadherin.

Heparan sulfate proteoglycans mediate the invasion of cardiomyocytes by Trypanosoma cruzi.

Cytoadherence is an important step for the invasion of a mammalian host cell by Trypanosoma cruzi. Cell surface macromolecules are implicated in the T. cruzi-cardiomyocyte recognition process. Therefore, we investigated the role of cell surface proteoglycans during this invasion process and analyzed their expression after the parasite infected the target cells. Treatment of trypomastigote forms of T. cruzi with soluble heparan sulfate resulted in a significant inhibition in successful invasion, while chondroitin sulfate had no effect. Removal of sulfated glycoconjugates from the cardiomyocyte surface using glycosaminoglycan (GAG) lyases demonstrated the specific binding of the parasites to heparan sulfate proteoglycans. Infection levels were reduced by 42% whenthe host cells were previously treated with heparitinase II. No changes were detected in the expression of GAGs infected cardiomyocytes even after 96 h of infection. Our data demonstrate that heparan sulfate proteoglycans, but not chondroitin sulfate, mediate both attachment and invasion of cardiomyocytes by T. cruzi.

Lipoprotein lipase mediates an increase in selective uptake of HDL-associated cholesteryl esters by cells in culture independent of scavenger receptor BI

Scavenger receptor class B type I (SR-BI) mediates the selective uptake of HDL cholesteryl esters (CEs) by the liver. LPL promotes this selective lipid uptake independent of lipolysis. In this study, the role of SR-BI in the mechanism of this LPL-mediated increase in selective CE uptake was explored. Baby hamster kidney (BHK) cells were transfected with the SR-BI cDNA, and significant SR-BI expression could be detected in immunoblots, whereas no SR-BI was visualized in control cells. Y1-BS1 murine adrenocortical cells were cultured without or with adrenocorticotropic hormone, and cells with no detectable or with SR-BI were obtained. These cells incubated without or with LPL in medium containing 125I/[3H]cholesteryl oleyl ether-labeled HDL3; tetrahydrolipstatin inhibited the catalytic activity of LPL. In BHK and in Y1-BS1 cells without or with SR-BI expression, apparent HDL3 selective CE uptake ([3H]CEt–125I) was detectable. Cellular SR-BI expression promoted HDL3 selective CE uptake by ~250–1,900%. In BHK or Y1-BS1 cells, LPL mediated an increase in apparent selective CE uptake. Quantitatively, this stimulating LPL effect was very similar in control cells and in cells with SR-BI expression. The uptake of radiolabeled HDL3 was also investigated in human embryonal kidney 293 (HEK 293) cells that are an established SR-BI-deficient cell model. LPL stimulated [3H]cholesteryl oleyl ether uptake from labeled HDL3 by HEK 293 cells substantially, showing that LPL can induce selective CE uptake from HDL3 independent of SR-BI. To explore the role of cell surface proteoglycans on lipoprotein uptake, we induced proteoglycan deficiency by heparinase treatment. Proteoglycan deficiency decreased the LPL-mediated promotion of HDL3 selective CE uptake. In summary, evidence is presented that the stimulating effect of LPL on HDL3 selective CE uptake is independent of SR-BI and lipolysis. However, cell surface proteoglycans are required for the LPL action on selective CE uptake. It is suggested that pathways distinct from SR-BI mediate selective CE uptake from HDL.—Rinninger, F., M. Brundert, I. Brosch, N. Donarski, R. M. Budzinski, and H. Greten. Lipoprotein lipase mediates an increase in selective uptake of HDL-associated cholesteryl esters by cells in culture independent of scavenger receptor BI.

Syndecans: transmembrane modulators of adhesion and matrix assembly.

Syndecans are transmembrane heparan sulfate proteoglycans (HSPGs) that are present on most cell types. HSPGs have been known for some time to regulate a variety of biological processes, ranging from coagulation cascades, growth factor signaling, lipase binding and activity, cell adhesion to ECM and subsequent cytoskeletal organization, to infection of cells with microorganisms. They are complex molecules, with specific core protein to which a variable number of glycosaminoglycan (GAG) chains are attached. Not only the number of chains varies; although syndecans mainly bear heparan sulfate GAGs, some have additional chondroitin/dermatan sulfate chains. Furthermore, heparan sulfate chains can vary in length, epimerization of glucuronic acid to iduronic acid, overall sulfation of the chains, and position of sulfation of the monosaccharides. Early studies relied on structurally nonspecific approaches such as competition with heparin or treatment with heparinases or chlorate to remove GAG chains or prevent their sulfation, respectively. These approaches defined a number of interacting ligands for heparan sulfates including insoluble ECM components and soluble growth factors and cytokines, and they helped to implicate HSPGs in a variety of biological processes (1–5). Cell surface HSPGs, including syndecans, appear to play modulatory roles, such as presenting growth factors to their primary receptors or increasing the infectivity of viruses by interacting with their primary receptors. In addition, these molecules can modify adhesion mediated by the integrins, the major family of receptors for ECM. This last function establishes a parallel between the syndecans (as well as other cell surface HSPGs) and the secreted matricellular proteins discussed elsewhere in this Perspective series. This is an exciting time to be in the field of syndecan research. Recently, there has been a surge of interest in the role of HSPGs and in identifying both the specific sequences of monosaccharides and sulfation patterns involved in ligand binding. With the cloning of various core proteins, it has become possible to study the features of these proteins that affect the ligand-binding ability and subsequent biological responses (reviewed in ref. 5; Table ​Table1).1). Now that tools are available to analyze individual protein cores, and techniques are becoming available to determine the sequence of their GAG chains, it is becoming evident that the protein and carbohydrate components of these molecules each play specific biological roles. Recent advances in “sequencing” of GAG chains present on individual proteoglycans have begun to allow structure to be correlated with function in these complex molecules. For example, a decasaccharide containing 2-O-sulfated iduronic acid and 6-O-sulfated N-acetylglucosamine is needed to potentiate the interaction of FGF-2 with its receptor. In contrast, a less specific sequence of seven to eight N-sulfated disaccharides containing iduronic acid (with or without 2-O-sulfation) serves to bind the higher affinity heparin-binding domain of fibronectin (HepII; ref. 5). This Perspective will concentrate on the syndecan family of transmembrane HSPGs and their roles in adhesion to ECM and subsequent matrix modification. In addition, it will address how syndecans may be pivotal in coordinating growth factor and adhesion signaling mechanisms. For discussion of some recent advances concerning the roles of cell surface proteoglycans in other fundamental biological processes, see refs. 2, 5, 6, and 7 and references therein. Table 1 Known ligands for HSPGs, where sulfation/epimerization patterns have been determined

Regulation of anti-HIV-1 activity of RANTES by heparan sulfate proteoglycans.

The role of cell surface proteoglycans in CC chemokine-mediated anti-HIV-1 activity in T cells and macrophages was investigated. Enzyme digestion of heparan sulfate (HS), but not chondroitin sulfate, from the surface of PM1(CD26H) cells (a human T cell line selected for high CD26 expression) rendered them resistant to the antiviral effects of RANTES and macrophage-inflammatory protein-1beta at otherwise inhibitory chemokine concentrations. HIV-1 infection of macrophages, however, was inhibited only partially, even at high concentrations of RANTES, and this inhibition was not prevented by HS removal. Flow cytometry revealed that digestion of cell surface proteoglycans, including HS, prevented the binding of RANTES at 10 to 100 nM concentrations to PM1(CD26H) cells. However, the binding of RANTES to activated macrophages occurred only at higher concentrations (100-300 nM) and was mostly chondroitin sulfate, and not HS, dependent. These results support a role for HS in facilitating the interaction of CC chemokines with the cell surface and the consequent inhibition of HIV-1 infection. The absence of HS-dependent binding of RANTES at lower concentrations to macrophages is consistent with the resistance of these cells to the antiviral effects of chemokines.

Nervous tissue proteoglycans.

The structure, biosynthesis, localization, and possible functional roles of nervous tissue glycosaminoglycans and proteoglycans were last reviewed several years ago. Since that time, there has been an exponential increase in publications on the neurobiology of proteoglycans. This review will therefore focus on reports which have appeared in the period after 1988, and especially on those concerning the properties of individual characterized nervous tissue proteoglycans. Related areas such as the regulation of glycosaminoglycan biosynthesis and the roles of cell surface proteoglycans in adhesion and growth control are covered in other contributions to this special topic issue.

Nervous tissue proteoglycans.

The structure, biosynthesis, localization, and possible functional roles of nervous tissue glycosaminoglycans and proteoglycans were last reviewed several years ago. Since that time, there has been an exponential increase in publications on the neurobiology of proteoglycans. This review will therefore focus on reports which have appeared in the period after 1988, and especially on those concerning the properties of individual characterized nervous tissue proteoglycans. Related areas such as the regulation of glycosaminoglycan biosynthesis and the roles of cell surface proteoglycans in adhesion and growth control are covered in other contributions to this special topic issue.

Cell-Surface Heparan Sulfate Proteoglycan Mediates HIV-1 Infection of T-Cell Lines

The role of cell-surface proteoglycans in human immunodeficiency virus (HIV) infection of T-cell lines was investigated. HIV-1-susceptible lymphoblastic T-cell lines, MT-4 and H9, were analyzed for proteoglycan synthesis and found to make heparan sulfate (HS) and chondroitin sulfate proteoglycans. Enzymatic treatment of these cells with heparitinase, but not chondroitinase, significantly prevented HIV-1(IIIB) infection as measured by inhibition of cytopathicity, reverse transcriptase production, and syncytia formation. Sulfation of glycosaminoglycans HS chains was critical to viral entry as shown by inhibition of viral infection with sodium chlorate and its specific reversal with exogenous sulfate addition. Quantitation of direct virus binding to cells showed that treatment of cells with heparitinase inhibited HIV-1 binding to the T-cell surface. Exogenous HS added to cultures inhibited virus infection in a manner analogous to dextran sulfate, further supporting a functional role for HS in HIV-1 binding. These results provide evidence for participation of cell-surface HS proteoglycans in HIV-cell attachment and virus entry.

Nervous Tissue Proteoglycans

The structure, biosynthesis, localization, and possible functional roles of nervous tissue glycosaminoglycans and proteoglycans were last reviewed several years ago70,74. Since that time, there has been an exponential increase in publications on the neurobiology of proteoglycans. This review will therefore focus on reports which have appeared in the period after 1988, and especially on those concerning the properties of individual characterized nervous tissue proteoglycans. Related areas such as the regulation of glycosaminoglycan biosynthesis and the roles of cell surface proteoglycans in adhesion and growth control are covered in other contributions to this special topic issue.