The Expression of Serglycin Is Required for Active Transforming Growth Factor β Receptor I Tumorigenic Signaling in Glioblastoma Cells and Paracrine Activation of Stromal Fibroblasts via CXCR-2

Serglycin (SRGN) is a pro-tumorigenic proteoglycan expressed and secreted by various aggressive tumors including glioblastoma (GBM). In our study, we investigated the interplay and biological outcomes of SRGN with TGFβRI, CXCR-2 and inflammatory mediators in GBM cells and fibroblasts. SRGN overexpression is associated with poor survival in GBM patients. High SRGN levels also exhibit a positive correlation with increased levels of various inflammatory mediators including members of TGFβ signaling pathway, cytokines and receptors including CXCR-2 and proteolytic enzymes in GBM patients. SRGN-suppressed GBM cells show decreased expressions of TGFβRI associated with lower responsiveness to the manipulation of TGFβ/TGFβRI pathway and the regulation of pro-tumorigenic properties. Active TGFβRI signaling in control GBM cells promotes their proliferation, invasion, proteolytic and inflammatory potential. Fibroblasts cultured with culture media derived by control SRGN-expressing GBM cells exhibit increased proliferation, migration and overexpression of cytokines and proteolytic enzymes including CXCL-1, IL-8, IL-6, IL-1β, CCL-20, CCL-2, and MMP-9. Culture media derived by SRGN-suppressed GBM cells fail to induce the above properties to fibroblasts. Importantly, the activation of fibroblasts by GBM cells not only relies on the expression of SRGN in GBM cells but also on active CXCR-2 signaling both in GBM cells and fibroblasts.

Resistance to hormone therapy in breast cancer cells promotes autophagy and EGFR signaling pathway

Breast cancer is the leading cause of cancer deaths for women worldwide. Endocrine therapies represent the cornerstone for hormone-dependent breast cancer treatment. However, in many cases, endocrine resistance is induced with poor prognosis for patients. In the current study, we have developed MCF-7 cell lines resistant to fulvestrant (MCF-7Fulv) and tamoxifen (MCF-7Tam) aiming at investigating mechanisms underlying resistance. Both resistant cell lines exerted lower proliferation capacity in two-dimensional (2-D) cultures but retain estrogen receptor α (ERα) expression and proliferate independent of the presence of estrogens. The established cell lines tend to be more aggressive exhibiting advanced capacity to form colonies, increased expression of epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER2), and heterodimerization of ERBB family receptors and activation of EGFR downstream pathways like MEK/ERK1/2 and PI3K/AKT. Tyrosine kinase inhibitors tested against resistant MCF-7Fulv and MCF-7Tam cells showed moderate efficacy to inhibit cell proliferation, except for lapatinib, which concomitantly inhibits both EGFR and HER2 receptors and strongly reduced cell proliferation. Furthermore, increased autophagy was observed in resistant MCF-7Fulv and MCF-7Tam cells as shown by the presence of autophagosomes and increased Beclin-1 levels. The increased autophagy in resistant cells is not associated with increased apoptosis, suggesting a cytoprotective role for autophagy that may favor cells' survival and aggressiveness. Thus, by exploiting those underlying mechanisms, new targets could be established to overcome endocrine resistance.NEW & NOTEWORTHY The development of resistance to hormone therapy caused by both fulvestrant and tamoxifen promotes autophagy with concomitant apoptosis evasion, rendering cells capable of surviving and growing. The fact that resistance also triggers ERBB family signaling pathways, which are poorly inhibited by tyrosine kinase inhibitors might attribute to cells' aggressiveness. It is obvious that the development of endocrine therapy resistance involves a complex interplay between deregulated ERBB signaling and autophagy that may be considered in clinical practice.

Enhancement of mesenchymal stem cells' chondrogenic potential by type II collagen-based bioscaffolds

BACKGROUND

Osteoarthritis (OA) is a common degenerative chronic disease accounting for physical pain, tissue stiffness and mobility restriction. Current therapeutic approaches fail to prevent the progression of the disease considering the limited knowledge on OA pathobiology. During OA progression, the extracellular matrix (ECM) of the cartilage is aberrantly remodeled by chondrocytes. Chondrocytes, being the main cell population of the cartilage, participate in cartilage regeneration process. To this end, modern tissue engineering strategies involve the recruitment of mesenchymal stem cells (MSCs) due to their regenerative capacity as to promote chondrocyte self-regeneration.

METHODS AND RESULTS

In the present study, we evaluated the role of type II collagen, as the main matrix macromolecule in the cartilage matrix, to promote chondrogenic differentiation in two MSC in vitro culture systems. The chondrogenic differentiation of human Wharton's jelly- and dental pulp-derived MSCs was investigated over a 24-day culture period on type II collagen coating to improve the binding affinity of MSCs. Functional assays, demonstrated that type II collagen promoted chondrogenic differentiation in both MSCs tested, which was confirmed through gene and protein analysis of major chondrogenic markers.

CONCLUSIONS

Our data support that type II collagen contributes as a natural bioscaffold enhancing chondrogenesis in both MSC models, thus enhancing the commitment of MSC-based therapeutic approaches in regenerative medicine to target OA and bring therapy closer to the clinical use.

Proteoglycans Determine the Dynamic Landscape of EMT and Cancer Cell Stemness

Proteoglycans (PGs) are pivotal components of extracellular matrices, involved in a variety of processes such as migration, invasion, morphogenesis, differentiation, drug resistance, and epithelial-to-mesenchymal transition (EMT). Cellular plasticity is a crucial intermediate phenotypic state acquired by cancer cells, which can modulate EMT and the generation of cancer stem cells (CSCs). PGs affect cell plasticity, stemness, and EMT, altering the cellular shape and functions. PGs control these functions, either by direct activation of signaling cascades, acting as co-receptors, or through regulation of the availability of biological compounds such as growth factors and cytokines. Differential expression of microRNAs is also associated with the expression of PGs and their interplay is implicated in the fine tuning of cancer cell phenotype and potential. This review summarizes the involvement of PGs in the regulation of EMT and stemness of cancer cells and highlights the molecular mechanisms.

Serglycin Is Involved in TGF-β Induced Epithelial-Mesenchymal Transition and Is Highly Expressed by Immune Cells in Breast Cancer Tissue

Serglycin is a proteoglycan highly expressed by immune cells, in which its functions are linked to storage, secretion, transport, and protection of chemokines, proteases, histamine, growth factors, and other bioactive molecules. In recent years, it has been demonstrated that serglycin is also expressed by several other cell types, such as endothelial cells, muscle cells, and multiple types of cancer cells. Here, we show that serglycin expression is upregulated in transforming growth factor beta (TGF-β) induced epithelial-mesenchymal transition (EMT). Functional studies provide evidence that serglycin plays an important role in the regulation of the transition between the epithelial and mesenchymal phenotypes, and it is a significant EMT marker gene. We further find that serglycin is more expressed by breast cancer cell lines with a mesenchymal phenotype as well as the basal-like subtype of breast cancers. By examining immune staining and single cell sequencing data of breast cancer tissue, we show that serglycin is highly expressed by infiltrating immune cells in breast tumor tissue.

A guide to the composition and functions of the extracellular matrix

Extracellular matrix (ECM) is a dynamic 3-dimensional network of macromolecules that provides structural support for the cells and tissues. Accumulated knowledge clearly demonstrated over the last decade that ECM plays key regulatory roles since it orchestrates cell signaling, functions, properties and morphology. Extracellularly secreted as well as cell-bound factors are among the major members of the ECM family. Proteins/glycoproteins, such as collagens, elastin, laminins and tenascins, proteoglycans and glycosaminoglycans, hyaluronan, and their cell receptors such as CD44 and integrins, responsible for cell adhesion, comprise a well-organized functional network with significant roles in health and disease. On the other hand, enzymes such as matrix metalloproteinases and specific glycosidases including heparanase and hyaluronidases contribute to matrix remodeling and affect human health. Several cell processes and functions, among them cell proliferation and survival, migration, differentiation, autophagy, angiogenesis, and immunity regulation are affected by certain matrix components. Structural alterations have been also well associated with disease progression. This guide on the composition and functions of the ECM gives a broad overview of the matrisome, the major ECM macromolecules, and their interaction networks within the ECM and with the cell surface, summarizes their main structural features and their roles in tissue organization and cell functions, and emphasizes the importance of specific ECM constituents in disease development and progression as well as the advances in molecular targeting of ECM to design new therapeutic strategies.

Serglycin activates pro-tumorigenic signaling and controls glioblastoma cell stemness, differentiation and invasive potential

Despite the functional role of serglycin as an intracellular proteoglycan, a variety of malignant cells depends on its expression and constitutive secretion to advance their aggressive behavior. Serglycin arose to be a biomarker for glioblastoma, which is the deadliest and most treatment-resistant form of brain tumor, but its role in this disease is not fully elucidated. In our study we suppressed the endogenous levels of serglycin in LN-18 glioblastoma cells to decipher its involvement in their malignant phenotype. Serglycin suppressed LN-18 (LN-18shSRGN) glioblastoma cells underwent astrocytic differentiation characterized by induced expression of GFAP, SPARCL-1 and SNAIL, with simultaneous loss of their stemness capacity. In particular, LN-18shSRGN cells presented decreased expression of glioma stem cell-related genes and ALDH1 activity, accompanied by reduced colony formation ability. Moreover, the suppression of serglycin in LN-18shSRGN cells retarded the proliferative and migratory rate, the invasive potential in vitro and the tumor burden in vivo. The lack of serglycin in LN-18shSRGN cells was followed by G2 arrest, with subsequent reduction of the expression of cell-cycle regulators. LN-18shSRGN cells also exhibited impaired expression and activity of proteolytic enzymes such as MMPs, TIMPs and uPA, both in vitro and in vivo. Moreover, suppression of serglycin in LN-18shSRGN cells eliminated the activation of pro-tumorigenic signal transduction. Of note, LN-18shSRGN cells displayed lower expression and secretion levels of IL-6, IL-8 and CXCR-2. Concomitant, serglycin suppressed LN-18shSRGN cells demonstrated repressed phosphorylation of ERK1/2, p38, SRC and STAT-3, which together with PI3K/AKT and IL-8/CXCR-2 signaling control LN-18 glioblastoma cell aggressiveness. Collectively, the absence of serglycin favors an astrocytic fate switch and a less aggressive phenotype, characterized by loss of pluripotency, block of the cell cycle, reduced ability for ECM proteolysis and pro-tumorigenic signaling attenuation.

Complexity of matrix phenotypes

The extracellular matrix is engaged in an ever-evolving and elegant ballet of dynamic reciprocity that directly and bi-directionally regulates cell behavior. Homeostatic and pathophysiological changes in cell-matrix signaling cascades manifest as complex matrix phenotypes. Indeed, the extracellular matrix can be implicated in virtually every known human disease, thus, making it the most critical and dynamic "organ" in the human body. The overall goal of this Special Issue is to provide an accurate and inclusive functional definition that addresses the inherent complexity of matrix phenotypes. This goal is summarily achieved via a corpus of expertly written articles, reviews and original research, focused at answering this question empirically and fundamentally via state-of-the-art methods and research strategies.

Tumorigenic functions of serglycin: Regulatory roles in epithelial to mesenchymal transition and oncogenic signaling

Numerous studies point out serglycin as an important regulator of tumorigenesis in a variety of malignancies. Serglycin expression correlates with the aggressive phenotype of tumor cells and serves as a poor prognostic indicator for disease progression. Although serglycin is considered as an intracellular proteoglycan, it is also secreted in the extracellular matrix by tumor cells affecting cell properties, oncogenic signaling and exosomes cargo. Serglycin directly interacts with CD44 and possibly other cell surface receptors including integrins, evoking cell adhesion and signaling. Serglycin also creates a pro-inflammatory and pro-angiogenic tumor microenvironment by regulating the secretion of proteolytic enzymes, IL-8, TGFβ2, CCL2, VEGF and HGF. Hence, serglycin activates multiple signaling cascades that drive angiogenesis, tumor cell growth, epithelial to mesenchymal transition, cancer cell stemness and metastasis. The interference with the tumorigenic functions of serglycin emerges as an attractive prospect to target malignancies.

The extracellular matrix as a multitasking player in disease

Extracellular matrices (ECMs) are highly specialized and dynamic three-dimensional (3D) scaffolds into which cells reside in tissues. ECM is composed of a variety of fibrillar components, such as collagens, fibronectin, and elastin, and non-fibrillar molecules as proteoglycans, hyaluronan, and glycoproteins including matricellular proteins. These macromolecular components are interconnected forming complex networks that actively communicate with cells through binding to cell surface receptors and/or matrix effectors. ECMs exert diverse roles, either providing tissues with structural integrity and mechanical properties essential for tissue functions or regulating cell phenotype and functions to maintain tissue homeostasis. ECM molecular composition and structure vary among tissues, and is markedly modified during normal tissue repair as well as during the progression of various diseases. Actually, abnormal ECM remodeling occurring in pathologic circumstances drives disease progression by regulating cell-matrix interactions. The importance of matrix molecules to normal tissue functions is also highlighted by mutations in matrix genes that give rise to genetic disorders with diverse clinical phenotypes. In this review, we present critical and emerging issues related to matrix assembly in tissues and the multitasking roles for ECM in diseases such as osteoarthritis, fibrosis, cancer, and genetic diseases. The mechanisms underlying the various matrix-based diseases are also discussed. Research focused on the highly dynamic 3D ECM networks will help to discover matrix-related causative abnormalities of diseases as well as novel diagnostic tools and therapeutic targets.

The Complex Interplay Between Extracellular Matrix and Cells in Tissues

Extracellular matrix (ECM) maintains the structural integrity of tissues and regulates cell and tissue functions. ECM is comprised of fibrillar proteins, proteoglycans (PGs), glycosaminoglycans, and glycoproteins, creating a heterogeneous but well-orchestrated network. This network communicates with resident cells via cell-surface receptors. In particular, integrins, CD44, discoidin domain receptors, and cell-surface PGs and additionally voltage-gated ion channels can interact with ECM components, regulating signaling cascades as well as cytoskeleton configuration. The interplay of ECM with recipient cells is enriched by the extracellular vesicles, as they accommodate ECM, signaling, and cytoskeleton molecules in their cargo. Along with the numerous biological properties that ECM can modify, autophagy and angiogenesis, which are critical for tissue homeostasis, are included. Throughout development and disease onset and progression, ECM endures rearrangement to fulfill cellular requirements. The main responsible molecules for tissue remodeling are ECM-degrading enzymes including matrix metalloproteinases, plasminogen activators, cathepsins, and hyaluronidases, which can modify the ECM structure and function in a dynamic mode. A brief summary of the complex interplay between ECM macromolecules and cells in tissues and the contribution of ECM in tissue homeostasis and diseases is given.

Matrix modeling and remodeling: A biological interplay regulating tissue homeostasis and diseases

The overall structure and architecture of the extracellular matrix undergo dramatic alterations in composition, form, and functionality over time. The stochasticity begins during development, essential for maintaining organismal homeostasis and is heavily implicated in many pathobiological states including fibrosis and cancer. Modeling and remodeling of the matrix is driven by the local cellular milieu and secreted and cell-associated components in a framework of dynamic reciprocity. This collection of expertly-written reviews aims to relay state-of-the-art information concerning the mechanisms of matrix modeling and remodeling in physiological development and disease.

Serglycin promotes breast cancer cell aggressiveness: Induction of epithelial to mesenchymal transition, proteolytic activity and IL-8 signaling

Serglycin is an intracellular proteoglycan that is expressed and constitutively secreted by numerous malignant cells, especially prominent in the highly-invasive, triple-negative MDA-MB-231 breast carcinoma cells. Notably, de novo expression of serglycin in low aggressive estrogen receptor α (ERα)-positive MCF7 breast cancer cells promotes an aggressive phenotype. In this study, we discovered that serglycin promoted epithelial to mesenchymal transition (EMT) in MCF7 cells as shown by increased expression of mesenchymal markers vimentin, fibronectin and EMT-related transcription factor Snail2. These phenotypic traits were also associated with the development of drug resistance toward various chemotherapy agents and induction of their proteolytic potential as shown by the increased expression of matrix metalloproteinases, including MMP-1, MMP-2, MMP-9, MT1-MMP and up-regulation of urokinase-type plasminogen activator. Knockdown of serglycin markedly reduced the expression of these proteolytic enzymes in MDA-MB-231 cells. In addition, serglycin expression was closely linked to a pro-inflammatory gene signature including the chemokine IL-8 in ERα-negative breast cancer cells and tumors. Notably, serglycin regulated the secretion of IL-8 in breast cancer cells independently of their ERα status and promoted their proliferation, migration and invasion by triggering IL-8/CXCR2 downstream signaling cascades including PI3K, Src and Rac activation. Thus, serglycin promotes the establishment of a pro-inflammatory milieu in breast cancer cells that evokes an invasive mesenchymal phenotype via autocrine activation of IL-8/CXCR2 signaling axis.

Insights into the key roles of epigenetics in matrix macromolecules-associated wound healing

Extracellular matrix (ECM) is a dynamic network of macromolecules, playing a regulatory role in cell functions, tissue regeneration and remodeling. Wound healing is a tissue repair process necessary for the maintenance of the functionality of tissues and organs. This highly orchestrated process is divided into four temporally overlapping phases, including hemostasis, inflammation, proliferation and tissue remodeling. The dynamic interplay between ECM and resident cells exerts its critical role in many aspects of wound healing, including cell proliferation, migration, differentiation, survival, matrix degradation and biosynthesis. Several epigenetic regulatory factors, such as the endogenous non-coding microRNAs (miRNAs), are the drivers of the wound healing response. microRNAs have pivotal roles in regulating ECM composition during wound healing and dermal regeneration. Their expression is associated with the distinct phases of wound healing and they serve as target biomarkers and targets for systematic regulation of wound repair. In this article we critically present the importance of epigenetics with particular emphasis on miRNAs regulating ECM components (i.e. glycoproteins, proteoglycans and matrix proteases) that are key players in wound healing. The clinical relevance of miRNA targeting as well as the delivery strategies designed for clinical applications are also presented and discussed.

Strategies to Target Matrix Metalloproteinases as Therapeutic Approach in Cancer

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that are capable of degrading numerous extracellular matrix (ECM) components thus participating in physiological and pathological processes. Apart from the remodeling of ECM, they affect cell-cell and cell-matrix interactions and are implicated in the development and progression of various diseases such as cancer. Numerous studies have demonstrated that MMPs evoke epithelial to mesenchymal transition (EMT) of cancer cells and affect their signaling, adhesion, migration and invasion to promote cancer cell aggressiveness. Various studies have suggested MMPs as suitable targets for treatment of malignancies, and several MMP inhibitors (MMPIs) have been developed. Although initial trials have failed to establish MMPIs as anticancer agents due to lack of specificity and side effects, new MMPIs have been developed with improved action that are currently being investigated. Furthermore, novel strategies that target MMPs for improving drug delivery and regulating their activity in tumors are presented. This review summarizes the implication of MMPs in cancer progression and discusses the advancements in their targeting.

Proteoglycans remodeling in cancer: Underlying molecular mechanisms

Extracellular matrix is a highly dynamic macromolecular network. Proteoglycans are major components of extracellular matrix playing key roles in its structural organization and cell signaling contributing to the control of numerous normal and pathological processes. As multifunctional molecules, proteoglycans participate in various cell functions during morphogenesis, wound healing, inflammation and tumorigenesis. Their interactions with matrix effectors, cell surface receptors and enzymes enable them with unique properties. In malignancy, extensive remodeling of tumor stroma is associated with marked alterations in proteoglycans' expression and structural variability. Proteoglycans exert diverse functions in tumor stroma in a cell-specific and context-specific manner and they mainly contribute to the formation of a permissive provisional matrix for tumor growth affecting tissue organization, cell-cell and cell-matrix interactions and tumor cell signaling. Proteoglycans also modulate cancer cell phenotype and properties, the development of drug resistance and tumor stroma angiogenesis. This review summarizes the proteoglycans remodeling and their novel biological roles in malignancies with particular emphasis to the underlying molecular mechanisms.

The role of heparins and nano-heparins as therapeutic tool in breast cancer

Glycosaminoglycans are integral part of the dynamic extracellular matrix (ECM) network that control crucial biochemical and biomechanical signals required for tissue morphogenesis, differentiation, homeostasis and cancer development. Breast cancer cells communicate with stromal ones to modulate ECM mainly through release of soluble effectors during cancer progression. The intracellular cross-talk between cell surface receptors and estrogen receptors is important for the regulation of breast cancer cell properties and production of ECM molecules. In turn, reorganized ECM-cell surface interface modulates signaling cascades, which regulate almost all aspects of breast cell behavior. Heparan sulfate chains present on cell surface and matrix proteoglycans are involved in regulation of breast cancer functions since they are capable of binding numerous matrix molecules, growth factors and inflammatory mediators thus modulating their signaling. In addition to its anticoagulant activity, there is accumulating evidence highlighting various anticancer activities of heparin and nano-heparin derivatives in numerous types of cancer. Importantly, heparin derivatives significantly reduce breast cancer cell proliferation and metastasis in vitro and in vivo models as well as regulates the expression profile of major ECM macromolecules, providing strong evidence for therapeutic targeting. Nano-formulations of the glycosaminoglycan heparin are possibly novel tools for targeting tumor microenvironment. In this review, the role of heparan sulfate/heparin and its nano-formulations in breast cancer biology are presented and discussed in terms of future pharmacological targeting.

Extracellular matrix structure

Extracellular matrix (ECM) is a non-cellular three-dimensional macromolecular network composed of collagens, proteoglycans/glycosaminoglycans, elastin, fibronectin, laminins, and several other glycoproteins. Matrix components bind each other as well as cell adhesion receptors forming a complex network into which cells reside in all tissues and organs. Cell surface receptors transduce signals into cells from ECM, which regulate diverse cellular functions, such as survival, growth, migration, and differentiation, and are vital for maintaining normal homeostasis. ECM is a highly dynamic structural network that continuously undergoes remodeling mediated by several matrix-degrading enzymes during normal and pathological conditions. Deregulation of ECM composition and structure is associated with the development and progression of several pathologic conditions. This article emphasizes in the complex ECM structure as to provide a better understanding of its dynamic structural and functional multipotency. Where relevant, the implication of the various families of ECM macromolecules in health and disease is also presented.

Advances and advantages of nanomedicine in the pharmacological targeting of hyaluronan-CD44 interactions and signaling in cancer

Extensive experimental evidence in cell and animal tumor models show that hyaluronan-CD44 interactions are crucial in both malignancy and resistance to cancer therapy. Because of the intimate relationship between the hyaluronan-CD44 system and tumor cell survival and growth, it is an increasingly investigated area for applications to anticancer chemotherapeutics. Interference with the hyaluronan-CD44 interaction by targeting drugs to CD44, targeting drugs to the hyaluronan matrix, or interfering with hyaluronan matrix/tumor cell-associated CD44 interactions is a viable strategy for cancer treatment. Many of these methods can decrease tumor burden in animal models but have yet to show significant clinical utility. Recent advances in nanomedicine have offered new valuable tools for cancer detection, prevention, and treatment. The enhanced permeability and retention effect has served as key rationale for using nanoparticles to treat solid tumors. However, the targeted and uniform delivery of these particles to all regions of tumors in sufficient quantities requires optimization. An ideal nanocarrier should be equipped with selective ligands that are highly or exclusively expressed on target cells and thus endow the carriers with specific targeting capabilities. In this review, we describe how the hyaluronan-CD44 system may provide such an alternative in tumors expressing specific CD44 variants.

Insights into the key roles of proteoglycans in breast cancer biology and translational medicine

Proteoglycans control numerous normal and pathological processes, among which are morphogenesis, tissue repair, inflammation, vascularization and cancer metastasis. During tumor development and growth, proteoglycan expression is markedly modified in the tumor microenvironment. Altered expression of proteoglycans on tumor and stromal cell membranes affects cancer cell signaling, growth and survival, cell adhesion, migration and angiogenesis. Despite the high complexity and heterogeneity of breast cancer, the rapid evolution in our knowledge that proteoglycans are among the key players in the breast tumor microenvironment suggests their potential as pharmacological targets in this type of cancer. It has been recently suggested that pharmacological treatment may target proteoglycan metabolism, their utilization as targets for immunotherapy or their direct use as therapeutic agents. The diversity inherent in the proteoglycans that will be presented herein provides the potential for multiple layers of regulation of breast tumor behavior. This review summarizes recent developments concerning the biology of selected proteoglycans in breast cancer, and presents potential targeted therapeutic approaches based on their novel key roles in breast cancer.

ADAMTS expression in colorectal cancer

ADAMTSs are a family of secreted proteinases that share the metalloproteinase domain with matrix metalloproteinases (MMPs). By acting on a large panel of extracellular substrates, they control several cell functions such as fusion, adhesion, proliferation and migration. Through their thrombospondin motifs they also possess anti-angiogenic properties. We investigated whether ADAMTSs participate in colorectal cancer progression and invasion. Their expression was investigated at both mRNA and protein levels. Using RT-PCR, the expression of ADAMTS-1, -4, -5 and ADAMTS-20 was estimated in colorectal tumors of different cancer stage and anatomic site and 3 cell lines of different aggressiveness. An overexpression of ADAMTS-4 and -5 was observed, especially in tissue samples, whereas ADAMTS-1 and -20 were found to be down-regulated. Western blot analysis further supported the RT-PCR findings, revealing in addition the degradation of ADAMTS-1 and -20 in cancer. In situ expression and localization of ADAMTS-1, -4, -5 and -20 was also investigated by immunohistochemical analysis. Our data suggest a positive correlation between ADAMTS-4 and -5 expression and cancer progression, in contrast with the anti-angiogenic members of the family, ADAMTS-1 and -20, which were found to be down-regulated. Our findings support the notion that overexpression of ADAMTS-4 and ADAMTS-5 in colorectal cancer might be a possible invasive mechanism of cancer cells in order to degrade proteoglycans of ECM.

Validated capillary electrophoretic assays for disaccharide composition analysis of galactosaminoglycans in biologic samples and drugs/nutraceuticals

Capillary electrophoresis is a separation technique with high resolving power and sensitivity with applications in glycosaminoglycan analysis. In this chapter, we present validated protocols for determining the variously sulfated chondroitin or dermatan sulfate-derived disaccharides. These approaches involve degradation of the polysaccharides with specific chondro/dermato-lyases and electrophoretic analysis with capillary zone electrophoresis in a low pH operating buffer and reversed polarity. This methodology has been applied to drug/nutraceutical formulations or to biologic samples (blood serum, lens capsule) and has been validated. Analysis of biologic tissue samples is often more demanding in terms of detection sensitivity, and thus concentration pretreatment steps and/or a derivatization step with 2-aminoacridone are often advisable.

Cell-matrix interactions: focus on proteoglycan-proteinase interplay and pharmacological targeting in cancer

Proteoglycans are major constituents of extracellular matrices, as well as cell surfaces and basement membranes. They play key roles in supporting the dynamic extracellular matrix by generating complex structural networks with other macromolecules and by regulating cellular phenotypes and signaling. It is becoming evident, however, that proteolytic enzymes are required partners for matrix remodeling and for modulating cell signaling via matrix constituents. Proteinases contribute to all stages of diseases, particularly cancer development and progression, and contextually participate in either the removal of damaged products or in the processing of matrix molecules and signaling receptors. The dynamic interplay between proteoglycans and proteolytic enzymes is a crucial biological step that contributes to the pathophysiology of cancer and inflammation. Moreover, proteoglycans are implicated in the expression and secretion of proteolytic enzymes and often modulate their activities. In this review, we describe the emerging biological roles of proteoglycans and proteinases, with a special emphasis on their complex interplay. We critically evaluate this important proteoglycan-proteinase interactome and discuss future challenges with respect to targeting this axis in the treatment of cancer.

Syndecans as modulators and potential pharmacological targets in cancer progression

Extracellular matrix (ECM) components form a dynamic network of key importance for cell function and properties. Key macromolecules in this interplay are syndecans (SDCs), a family of transmembrane heparan sulfate proteoglycans (HSPGs). Specifically, heparan sulfate (HS) chains with their different sulfation pattern have the ability to interact with growth factors and their receptors in tumor microenvironment, promoting the activation of different signaling cascades that regulate tumor cell behavior. The affinity of HS chains with ligands is altered during malignant conditions because of the modification of chain sequence/sulfation pattern. Furthermore, matrix degradation enzymes derived from the tumor itself or the tumor microenvironment, like heparanase and matrix metalloproteinases, ADAM as well as ADAMTS are involved in the cleavage of SDCs ectodomain at the HS and protein core level, respectively. Such released soluble SDCs "shed SDCs" in the ECM interact in an autocrine or paracrine manner with the tumor or/and stromal cells. Shed SDCs, upon binding to several matrix effectors, such as growth factors, chemokines, and cytokines, have the ability to act as competitive inhibitors for membrane proteoglycans, and modulate the inflammatory microenvironment of cancer cells. It is notable that SDCs and their soluble counterparts may affect either the behavior of cancer cells and/or their microenvironment during cancer progression. The importance of these molecules has been highlighted since HSPGs have been proposed as prognostic markers of solid tumors and hematopoietic malignancies. Going a step further down the line, the multi-actions of SDCs in many levels make them appealing as potential pharmacological targets, either by targeting directly the tumor or indirectly the adjacent stroma.

Serglycin: at the crossroad of inflammation and malignancy

Serglycin has been initially characterized as an intracellular proteoglycan expressed by hematopoietic cells. All inflammatory cells highly synthesize serglycin and store it in granules, where it interacts with numerous inflammatory mediators, such as proteases, chemokines, cytokines, and growth factors. Serglycin is implicated in their storage into the granules and their protection since they are secreted as complexes and delivered to their targets after secretion. During the last decade, numerous studies have demonstrated that serglycin is also synthesized by various non-hematopoietic cell types. It has been shown that serglycin is highly expressed by tumor cells and promotes their aggressive phenotype and confers resistance against drugs and complement system attack. Apart from its direct beneficial role to tumor cells, serglycin may promote the inflammatory process in the tumor cell microenvironment thus enhancing tumor development. In the present review, we discuss the role of serglycin in inflammation and tumor progression.

Serglycin is implicated in the promotion of aggressive phenotype of breast cancer cells

Serglycin is a proteoglycan expressed by some malignant cells. It promotes metastasis and protects some tumor cells from complement system attack. In the present study, we show for the first time the in situ expression of serglycin by breast cancer cells by immunohistochemistry in patients' material. Moreover, we demonstrate high expression and constitutive secretion of serglycin in the aggressive MDA-MB-231 breast cancer cell line. Serglycin exhibited a strong cytoplasmic staining in these cells, observable at the cell periphery in a thread of filaments near the cell membrane, but also in filopodia-like structures. Serglycin was purified from conditioned medium of MDA-MB-231 cells, and represented the major proteoglycan secreted by these cells, having a molecular size of ~ 250 kDa and carrying chondroitin sulfate side chains, mainly composed of 4-sulfated (~ 87%), 6-sulfated (~ 10%) and non-sulfated (~ 3%) disaccharides. Purified serglycin inhibited early steps of both the classical and the lectin pathways of complement by binding to C1q and mannose-binding lectin. Stable expression of serglycin in less aggressive MCF-7 breast cancer cells induced their proliferation, anchorage-independent growth, migration and invasion. Interestingly, over-expression of serglycin lacking the glycosaminoglycan attachment sites failed to promote these cellular functions, suggesting that glycanation of serglycin is a pre-requisite for its oncogenic properties. Our findings suggest that serglycin promotes a more aggressive cancer cell phenotype and may protect breast cancer cells from complement attack supporting their survival and expansion.

Cross-talk between estradiol receptor and EGFR/IGF-IR signaling pathways in estrogen-responsive breast cancers: focus on the role and impact of proteoglycans

In hormone-dependent breast cancer, estrogen receptors are the principal signaling molecules that regulate several cell functions either by the genomic pathway acting directly as transcription factors in the nucleus or by the non-genomic pathway interacting with other receptors and their adjacent pathways like EGFR/IGFR. It is well established in literature that EGFR and IGFR signaling pathways promote cell proliferation and differentiation. Moreover, recent data indicate the cross-talk between ERs and EGFR/IGFR signaling pathways causing a transformation of cell functions as well as deregulation on normal expression pattern of matrix molecules. Specifically, proteoglycans, a major category of extracellular matrix (ECM) and cell surface macromolecules, are modified during malignancy and cause alterations in cancer cell signaling, affecting eventually functional cell properties such as proliferation, adhesion and migration. The on-going strategies to block only one of the above signaling effectors result cancer cells to overcome such inactivation using alternative signaling pathways. In this article, we therefore review the underlying mechanisms in respect to the role of ERs and the involvement of cross-talk between ERs, IGFR and EGFR in breast cancer cell properties and expression of extracellular secreted and cell bound proteoglycans involved in cancer progression. Understanding such signaling pathways may help to establish new potential pharmacological targets in terms of using ECM molecules to design novel anticancer therapies.

Cell-surface serglycin promotes adhesion of myeloma cells to collagen type I and affects the expression of matrix metalloproteinases

Serglycin (SG) is mainly expressed by hematopoetic cells as an intracellular proteoglycan. Multiple myeloma cells constitutively secrete SG, which is also localized on the cell surface in some cell lines. In this study, SG isolated from myeloma cells was found to interact with collagen type I (Col I), which is a major bone matrix component. Notably, myeloma cells positive for cell-surface SG (csSG) adhered significantly to Col I, compared to cells lacking csSG. Removal of csSG by treatment of the cells with chondroitinase ABC or blocking of csSG by an SG-specific polyclonal antibody significantly reduced the adhesion of myeloma cells to Col I. Significant up-regulation of expression of the matrix metalloproteinases MMP-2 and MMP-9 at both the mRNA and protein levels was observed when culturing csSG-positive myeloma cells on Col I-coated dishes or in the presence of soluble Col I. MMP-9 and MMP-2 were also expressed in increased amounts by myeloma cells in the bone marrow of patients with multiple myeloma. Our data indicate that csSG of myeloma cells affects key functional properties, such as adhesion to Col I and the expression of MMPs, and imply that csSG may serve as a potential prognostic factor and/or target for pharmacological interventions in multiple myeloma.

Preclinical evaluation of zoledronate using an in vitro mimetic cellular model for breast cancer metastatic bone disease

BACKGROUND

The interactions between metastatic breast cancer cells and host cells of osteoclastic lineage in bone microenvironment are essential for osteolysis. In vitro studies to evaluate pharmacological agents are mainly limited to their direct effects on cell lines. To mimic the communication between breast cancer cells and human osteoclasts, a simple and reproducible cellular model was established to evaluate the effects of zoledronate (zoledronic acid, ZOL), a bisphosphonate which exerts antiresorptive properties.

METHODS

Human precursor osteoclasts were cultured on bone-like surfaces in the presence of stimuli (sRANKL, M-CSF) to ensure their activation. Furthermore, immature as well as activated osteoclasts were co-cultured with MDA-MB-231 breast cancer cells. TRAP5b and type I collagen N-terminal telopeptide (NTx) were used as markers. Osteoclasts' adhesion to bone surface and subsequent bone breakdown were evaluated by studying the expression of cell surface receptors and certain functional matrix macromolecules in the presence of ZOL.

RESULTS

ZOL significantly suppresses the precursor osteoclast maturation, even when the activation stimuli (sRANKL and M-SCF) are present. Moreover, it significantly decreases bone osteolysis and activity of MMPs as well as precursor osteoclast maturation by breast cancer cells. Additionally, ZOL inhibits the osteolytic activity of mature osteoclasts and the expression of integrin β3, matrix metalloproteinases and cathepsin K, all implicated in adhesion and bone resorption.

CONCLUSIONS

ZOL exhibits a beneficial inhibitory effect by restricting activation of osteoclasts, bone particle decomposition and the MMP-related breast cancer osteolysis.

GENERAL SIGNIFICANCE

The proposed cellular model can be reliably used for enhancing preclinical evaluation of pharmacological agents in metastatic bone disease.

Efficient TGFβ-induced epithelial-mesenchymal transition depends on hyaluronan synthase HAS2

Epithelial-mesenchymal transition (EMT) is a developmental program, which can be adopted by cancer cells to increase their migration and ability to form metastases. Transforming growth factor β (TGFβ) is a well-studied inducer of EMT. We demonstrate that TGFβ potently stimulates hyaluronan synthesis via upregulation of hyaluronan synthase 2 (HAS2) in NMuMG mammary epithelial cells. This stimulatory effect requires the kinase active type I TGFβ receptor and is dependent on Smad signaling and activation of the p38 mitogen-activated protein kinase. Knockdown of HAS2 inhibited the TGFβ-induced EMT by about 50%, as determined by the phase contrast microscopy and immunostaining using the EMT marker ZO-1. Furthermore, real-time PCR analysis of the EMT markers fibronectin, Snail1 and Zeb1 revealed decreased expressions upon HAS2 suppression, using specific small interfering RNA (siRNA) for HAS2. Removal of the extracellular hyaluronan by Streptomyces hyaluronidase or inhibiting the binding to its cell surface receptor CD44 by blocking antibodies, did not inhibit TGFβ-induced EMT. Interestingly, HAS2 suppression completely abolished the TGFβ-induced cell migration, whereas CD44 knockdown did not. These observations suggest that TGFβ-dependent HAS2 expression, but not extracellular hyaluronan, has an important regulatory role in TGFβ-induced EMT.

Imbalance of MMP-2 and MMP-9 expression versus TIMP-1 and TIMP-2 reflects increased invasiveness of human testicular germ cell tumours

The histological classification of testicular germ cell tumours (TGCTs) to seminoma or non-seminomatous germ cell tumours is at present the main criterion for the clinical outcome and selection of the treatment strategy. In view of the need to identify novel prognostic biomarkers for TGCTs, we investigated the expression of the matrix metalloproteinases MMP-2 and MMP-9 in testicular tumour tissues and cell lines of both seminoma and non-seminoma origin. Immunohistochemistry and zymography analysis of tumoural tissues showed significantly higher levels of MMP-2 and MMP-9 compared with normal testis with the active forms detected only in the tumour tissues. Three cell lines representative of the different tumour types, JKT-1 seminoma, NCCIT teratocarcinoma and NTERA2/D1 embryonal carcinoma were also evaluated for their expression of these MMPs using qPCR and zymography and for their invasive properties. The more invasive non-seminomatous teratocarcinoma and embryonal cells expressed considerably more MMP-2 and MMP-9 compared with seminoma cells exhibiting lower invasiveness. Furthermore, an inverse relation was observed between invasiveness and the expression of endogenous inhibitors TIMP-1 and TIMP-2. The MMP inhibitor Marimastat inhibited invasion in all cell lines, the highest inhibition was observed in the more invasive NTERA2/D1 and NCCIT cells, which presented the highest ratio of MMP-2 and MMP-9 vs. TIMP-1 and TIMP-2. These results highlight the importance of MMP-2 and MMP-9 in the invasiveness of testicular tumours and suggest that their levels, vs. those of TIMP-1 and TIMP-2, may represent potential biomarkers for testicular malignancy.

Pathophysiology and pharmacological targeting of tumor-induced bone disease: current status and emerging therapeutic interventions

Bone disease is a common complication of metastatic solid tumors but also of primary hematological malignancies such as multiple myeloma. Our understanding of the molecular mechanisms underlying the development of bone disease by solid tumors and multiple myeloma has been significantly improved. A complex inter-dependence exists between bone disease and malignant cell growth, creating a vicious cycle of extensive bone destruction and tumor progression. Although myeloma and solid tumors share a number of common molecular pathogenetic mechanisms, they involve distinct pathophysiological pathways, resulting in osteoclastic bone resorption and inhibition of bone formation. In this review, we analyze the molecular mechanisms, involved in tumor-induced bone disease and discuss the current therapeutic approaches and the most recent clinical developments of emerging targeted therapies.

Versican but not decorin accumulation is related to malignancy in mammographically detected high density and malignant-appearing microcalcifications in non-palpable breast carcinomas

Background

Mammographic density (MD) and malignant-appearing microcalcifications (MAMCs) represent the earliest mammographic findings of non-palpable breast carcinomas. Matrix proteoglycans versican and decorin are frequently over-expressed in various malignancies and are differently involved in the progression of cancer. In the present study, we have evaluated the expression of versican and decorin in non-palpable breast carcinomas and their association with high risk mammographic findings and tumor characteristics.

Methods

Three hundred and ten patients with non-palpable suspicious breast lesions, detected during screening mammography, were studied. Histological examination was carried out and the expression of decorin, versican, estrogen receptor α (ERα), progesterone receptor (PR) and c-erbB2 (HER-2/neu) was assessed by immunohistochemistry.

Results

Histological examination showed 83 out of 310 (26.8%) carcinomas of various subtypes. Immunohistochemistry was carried out in 62/83 carcinomas. Decorin was accumulated in breast tissues with MD and MAMCs independently of the presence of malignancy. In contrast, versican was significantly increased only in carcinomas with MAMCs (median ± SE: 42.0 ± 9.1) and MD (22.5 ± 10.1) as compared to normal breast tissue with MAMCs (14.0 ± 5.8), MD (11.0 ± 4.4) and normal breast tissue without mammographic findings (10.0 ± 2.0). Elevated levels of versican were correlated with higher tumor grade and invasiveness in carcinomas with MD and MAMCs, whereas increased amounts of decorin were associated with in situ carcinomas in MAMCs. Stromal deposition of both proteoglycans was related to higher expression of ERα and PR in tumor cells only in MAMCs.

Conclusions

The specific accumulation of versican in breast tissue with high MD and MAMCs only in the presence of malignant transformation and its association with the aggressiveness of the tumor suggests its possible use as molecular marker in non-palpable breast carcinomas.

Glycosaminoglycans as key molecules in atherosclerosis: the role of versican and hyaluronan

Cardiovascular disease is the largest cause of death in Western societies and it primarily results from atherosclerosis of large and medium-sized vessels. Atherosclerosis leads to myocardial infarction, when it occurs in the coronary arteries, or stroke, when it occurs in the cerebral arteries. Pathological processes involved in macrovascular disease include the accumulation of lipids which are retained by extracellular matrix (ECM) molecules, especially by the chondroitin sulfate/dermatan sulfate (CS/DS) proteoglycans (CS/DSPGs), such as versican, biglycan and decorin. The sulfation pattern of CS is a key player in protein interactions causing atherosclerosis. Several studies have shown that lipoproteins bind CSPGs via their glycosaminoglycan chains. Galactosaminoglycans, such as CS and DS, bind low density lipoproteins (LDL), affecting the role of these molecules in the arterial wall. In this article, the role of CS and versican in atherosclerosis and hyaluronan in atherogenesis as well as the up to date known mechanisms that provoke this pathological condition are presented and discussed.

Serglycin inhibits the classical and lectin pathways of complement via its glycosaminoglycan chains: implications for multiple myeloma

Serglycin (SG) is a proteoglycan expressed by hematopoietic cells and is constitutively secreted by multiple myeloma (MM) cells. SG participates in the regulation of various inflammatory events. We found that SG secreted by human MM cell lines inhibits both the classical and lectin pathways of complement, without influencing alternative pathway activity. The inhibitory effect of SG is due to direct interactions with C1q and mannose-binding lectin (MBL). C1q-binding is mediated through the glycosaminoglycan moieties of SG, whereas MBL binds additionally to SG protein core. Interactions between SG and C1q as well as MBL are diminished in the presence of chondroitin sulfate type E. In addition, we localized the SG-binding site to the collagen-like stalk of C1q. Interactions between SG and C1q as well as MBL are ionic in character and only the interaction with MBL was found to be partially dependent on the presence of calcium. We found the serum levels of SG to be elevated in patients with MM compared to healthy controls. Moreover, we found that SG expressed from myeloma plasma cells protects these cells from complement activation induced by treatment with anti-thymocyte immunoglobulins. This might protect myeloma cells during immunotherapy and promote survival of malignant cells.

Roles of matrix metalloproteinases in cancer progression and their pharmacological targeting

Matrix metalloproteinases (MMPs) consist of a multigene family of zinc-dependent extracellular matrix (ECM) remodeling endopeptidases implicated in pathological processes, such as carcinogenesis. In this regard, their activity plays a pivotal role in tumor growth and the multistep processes of invasion and metastasis, including proteolytic degradation of ECM, alteration of the cell-cell and cell-ECM interactions, migration and angiogenesis. The underlying premise of the current minireview is that MMPs are able to proteolytically process substrates in the extracellular milieu and, in so doing, promote tumor progression. However, certain members of the MMP family exert contradicting roles at different stages during cancer progression, depending among other factors on the tumor stage, tumor site, enzyme localization and substrate profile. MMPs are therefore amenable to therapeutic intervention by synthetic and natural inhibitors, providing perspectives for future studies. Multiple therapeutic agents, called matrix metalloproteinase inhibitors (MMPIs) have been developed to target MMPs, attempting to control their enzymatic activity. Even though clinical trials with these compounds do not show the expected results in most cases, the field of MMPIs is ongoing. This minireview critically evaluates the role of MMPs in relation to cancer progression, and highlights the challenges, as well as future prospects, for the design, development and efficacy of MMPIs.

Proteoglycans in health and disease: novel roles for proteoglycans in malignancy and their pharmacological targeting

The expression of proteoglycans (PGs), essential macromolecules of the tumor microenvironment, is markedly altered during malignant transformation and tumor progression. Synthesis of stromal PGs is affected by factors secreted by cancer cells and the unique tumor-modified extracellular matrix may either facilitate or counteract the growth of solid tumors. The emerging theme is that this dual activity has intrinsic tissue specificity. Matrix-accumulated PGs, such as versican, perlecan and small leucine-rich PGs, affect cancer cell signaling, growth and survival, cell adhesion, migration and angiogenesis. Furthermore, expression of cell-surface-associated PGs, such as syndecans and glypicans, is also modulated in both tumor and stromal cells. Cell-surface-associated PGs bind various factors that are involved in cell signaling, thereby affecting cell proliferation, adhesion and motility. An important mechanism of action is offered by a proteolytic processing of cell-surface PGs known as ectodomain shedding of syndecans; this facilitates cancer and endothelial cell motility, protects matrix proteases and provides a chemotactic gradient of mitogens. However, syndecans on stromal cells may be important for stromal cell/cancer cell interplay and may promote stromal cell proliferation, migration and angiogenesis. Finally, abnormal PG expression in cancer and stromal cells may serve as a biomarker for tumor progression and patient survival. Enhanced understanding of the regulation of PG metabolism and the involvement of PGs in cancer may offer a novel approach to cancer therapy by targeting the tumor microenvironment. In this minireview, the implication of PGs in cancer development and progression, as well as their pharmacological targeting in malignancy, are presented and discussed.

Immunization with Specific Polysaccharide Antigen Reduces Alterations in Corneal Proteoglycans During Experimental Slime-ProducingStaphylococcus epidermidisKeratitis

PURPOSE

Staphylococcus epidermidis is a leading cause of bacterial keratitis associated with corneal damage. Corneal integrity is closely associated with matrix macromolecules, such as proteoglycans (PGs) and collagen. The aim of this study was to examine whether active immunization (AI) using a major immunogenic polysaccharide determinant of slime (20-kDa PS) as antigen, and passive immunization (PI) after administration of specific antibodies toward 20-kDa PS affect the distribution of PGs as well as corneal lesions in an experimental model of slime-producing S. epidermidis keratitis.

METHODS

For AI, seven rabbits were immunized with 20-kDa PS, whereas for PI, seven rabbits received specific antibodies against 20-kDa PS. Lesions were graded clinically for a 21-day period. Levels of 20-kDa PS antibodies in serum and aqueous humor in both immunization groups were determined by ELISA. The distribution of certain extracellular matrix PGs during corneal healing was analyzed immunohistochemically.

RESULTS

Levels of specific anti-20-kDa PS antibodies in serum and aqueous humor obtained after either AI or PI were significantly higher as compared with those in the respective nonimmunized control groups (p<0.001). Clinical grading showed that both AI and PI rabbits had a significantly less corneal damage as compared with infected nontreated rabbits. Immunohistochemical analyses for PGs exhibited significant differences to the wounded regions as compared with noninfected corneal tissue. Accumulation of keratan sulfate PGs and decorin was observed in the corneal stroma of infected rabbits and of heparan sulfate PGs around the new-formed vessels. This phenomenon was significantly reduced in immunized animals in accordance with macroscopically decreased corneal damage observed in these animals.

CONCLUSIONS

Results of this study suggest a key role of 20-kDa PS and its antibodies as prophylactic and therapeutic agents in keratitis caused by slime-producing S. epidermidis.

Glycosaminoglycan in cerebrum, cerebellum and brainstem of young sheep brain with particular reference to compositional and structural variations of chondroitin-dermatan sulfate and hyaluronan

Recent advances in the structural biology of chondroitin sulfate chains have suggested important biological functions in the development of the brain. Several studies have demonstrated that the composition of chondroitin sulfate chains changes with aging and normal brain maturation. In this study, we determined the concentration of all glycosaminoglycan types, i.e. chondroitin sulfate, dermatan sulfate, keratan sulfate, heparan sulfate, hyaluronan and chondroitin in cerebrum, cerebellum and brainstem of young sheep brain. In all cases, chondroitin sulfate was the predominant glycosaminoglycan type, comprising about 54-58% of total glycosaminoglycans, with hyaluronan being present also in significant amounts of about 19-28%. Of particular interest was the increased presence of the disulfated disaccharides and dermatan sulfate in cerebellum and brainstem, respectively, as well as the detectable and measurable occurrence of chondroitin in young sheep brain. Among the three brain areas, cerebrum was found to be significantly richer in chondroitin sulfate and hyaluronan, two major extracellular matrix components. These findings imply that the extracellular matrix of the cerebrum is different from those of cerebellum and brainstem, and probably this fact is related to the particular histological and functional characteristics of each anatomic area of the brain.

Estradiol-estrogen receptor: a key interplay of the expression of syndecan-2 and metalloproteinase-9 in breast cancer cells

Estrogens are related with the growth and development of target tissues and play a critical role in breast cancer progression. The effects of estrogens are mediated by the estrogen receptors ERalpha and ERbeta, which are members of the nuclear steroid receptor superfamily. To date, it is not known how these hormones elicit many of their effects on extracellular matrix molecules and how these effects can be connected with ER expression. For this purpose, the effect of estradiol on ER expression as well as on proteoglycan and metalloproteinase expression was studied. The effect of E2 on extracellular matrix molecule expression has been studied using ERalpha suppression in breast cancer cells. Our studies using ERalpha-positive MCF-7 cells show that estradiol affects the expression of syndecan-2, but not of syndecan-4, through ERalpha. Furthermore, the ability of estradiol to affect MMP-9 and TIMP-1 expression is connected with ERalpha status. Together, these data demonstrate the significant role of ERalpha on mediating the effect of estradiol on extracellular matrix molecules.