The dual role of the glycosaminoglycan chondroitin-6-sulfate in the development, progression and metastasis of cancer

The remarkable structural heterogeneity of chondroitin sulfate (CS) and dermatan sulfate (DS) generates biological information that can be unique to each of these glycosaminoglycans (GAGs), and changes in their composition are translated into alterations in the binding profiles of these molecules. CS/DS can bind to various cytokines and growth factors, cell surface receptors, adhesion molecules, enzymes and fibrillar glycoproteins of the extracellular matrix, thereby influencing both cell behavior and the biomechanical and biochemical properties of the matrix. In this review, we summarize the current knowledge concerning CS/DS metabolism in the human cancer stroma. The remodeling of the GAG profile in the tumor niche is manifested as a substantial increase in the CS content and a gradual decrease in the proportion between DS and CS. Furthermore, the composition of CS and DS is also affected, which results in a substantial increase in the 6‐O‐sulfated and/or unsulfated disaccharide content, which is concomitant with a decrease in the 4‐O‐sulfation level. Here, we discuss the possible impact of alterations in the CS/DS sulfation pattern on the binding capacity and specificity of these GAGs. Moreover, we propose potential consequences of the stromal accumulation of chondroitin‐6‐sulfate for the progression and metastasis of cancer.

Effects of a 15-month anti-TNF-α treatment on plasma levels of glycosaminoglycans in women with rheumatoid arthritis

Background

In this study, the effect of 15-month anti-tumor necrosis factor alpha (TNF-α) treatment on circulating levels of plasma sulfated glycosaminoglycans (GAGs) and the nonsulfated GAG hyaluronic acid (HA) in female rheumatoid arthritis (RA) patients was assessed.

Methods

Plasma was obtained from healthy subjects and RA women treated with TNF-α antagonists (etanercept or adalimumab or certolizumab pegol) in combination with methotrexate. GAGs were isolated from plasma samples using ion exchange low-pressure liquid chromatography. Total sulfated GAGs were quantified using a hexuronic acid assay. Plasma levels of keratan sulfate (KS) and HA were measured using immunoassay kits.

Results

Total sulfated GAGs and HA levels were higher in female RA patients before treatment in comparison to healthy subjects. KS levels did not differ between RA women and controls. Anti-TNF-α treatment resulted in normalization of plasma total GAG and HA levels in RA patients, without any effect on KS levels.

Conclusions

Our results suggest that anti-TNF-α therapy has a beneficial effect on extracellular matrix remodeling in the course of RA.

Alterations in the extracellular matrix proteoglycan profile in Dupuytren's contracture affect the palmar fascia

Dupuytren's disease is a palmar fibromatosis associated with changes in fibroblast activity that also affect the metabolism of extracellular matrix components. In contrast to disease connected alterations in collagen and non-collagenous glycoproteins (mainly fibronectin), the metabolism of proteoglycans, being glycosaminoglycan modified glycoproteins, is poorly understood. Thus, the aim of the present study was the characterization of matrix proteoglycans (PGs) derived from normal fascia and Dupuytren's fascia. Extracted and purified PGs (particularly small PGs) were analysed for content, molecular mass, immunoreactivity and glycosaminoglycan chain structure. The matrix of normal fascia mainly contains decorin [small dermatan sulfate (DS) PG] with biglycan (another small DSPG) and large chondroitin sulfate(CS)/DSPG representing minor components. Dupuytren's disease is associated with the remodeling of matrix PG composition. The most prominent alteration is an accumulation of biglycan frequently bearing DS chains with higher molecular masses. Moreover, the amount of large CS/DSPG is increased. In contrast, decorin displays changes affecting mainly DS chain structure reflected in (i) an increase in some chain molecular masses, (ii) an enhanced content of iduronate disaccharide clusters, and (iii) oversulfation of disaccharide repeats. The PG alterations observed in Dupuytren's fascia may influence the matrix properties and contribute to disease progression.

[Methods of collagenous tissue fixation in the preparation of bioprostheses]

The use of biological materials in construction of bioprostheses requires the application of different chemical or physical procedures of fixation increasing bioprostheses resistance to enzymatic or chemical degradation and reducing their antigenicity. Methods typically concentrate on creating additional intra- and intermolecular chemical bonds between collagen molecules. This review focuses on the various methods of stabilization of collagenous tissues including chemical fixatives and physical agents.

Serum matrix-degrading enzymes in rats intoxicated with selenium

The effect of poisoning doses of selenium on serum matrix-degrading enzymes activity was investigated in rats intoxicated with selenium. Fifteen animals were receiving orally sodium selenite in a daily dose of 300 microg/kg body weight. Intoxication with selenium was carried out for 10 weeks. The present study revealed significant increase in activities of enzymes involved in the connective tissue matrix metabolism i.e. beta-glucuronidase, N-acetyl-beta-glucosaminidase, elastase and collagen peptidase. There was no change in the cathepsin activity. The relative enzyme activities calculated over protein level resulted in higher values than those found in direct measurements. Serum enzyme activity was increased most for elastase (about 31%) and N-acetyl-beta-glucosaminidase (about 33%) based on activity per gram of protein. The current data indicate that lysosomes are target organelles for selenium toxicity. Generalized increase in lysosomal enzymes activity contributes to the altered metabolism of the connective tissue in selenium-intoxicated animals. The mechanisms that lead to the increase of lysosomal enzymes activity in rats receiving poisoning doses of selenium could be related to biochemical disturbances caused by selenium toxicity.

An accumulation of proteoglycans in scarred fascia

A little is known about proteoglycan (PG) changes, occuring in the course of scarring of tissues another than skin. The aim of present study was biochemical characterization of glycosaminoglycans (GAGs) and proteoglycans (PGs) of normal and scarred fascia. Samples of normal fascia lata were taken at autopsy from 23 individuals and samples of scarred fascia lata were removed from 23 patients at reoperations for femoral fracture. The obtained tissues were divided into two samples: first of them was submitted to GAG isolation and the second one to PG isolation. GAGs were extracted by extensive papain digestion followed by the fractionation using cetylpyridinium chloride. In order to qualitative and quantitative characterization GAGs were submitted to electrophoresis on cellulose acetate before and after treatment with enzymes, specifically depolymerizing some kinds of GAGs. PGs were extracted using 4 M guanidine HCl followed by purification by forming complexes with Alcian blue. PGs were submitted to gel permeation chromatography on Sepharose 4B. In order to obtain core proteins PGs were depolymerized with chondroitinase ABC. The purified PGs and their core proteins were separated with sodium dodecyl sulphate/polyacrylamide gel electrophoresis (SDS/PAGE). It was found that total GAGs content was significantly elevated in scarred fascia. Both types of fascia contained chondroitin-, dermatan- and heparan sulphates and hyaluronic acid. Dermatan sulphates (DS) were the predominant GAGs of normal and scarred fascia. The contents of all GAG types were increased in scarred fascia. Both types of fascia contained two kinds of dermatan sulphate proteoglycans (DSPGs); first being similar to biglycan and the second one similar to decorin, as it was judged by molecular weight of their native molecules and core proteins as well as type of GAG components. Densitometric analysis showed that decorin is a predominant DSPG in both fascia types, but in scarred tissue the ratio of biglycan to decorin is considerably higher. Moreover, in scarred fascia a large chondroitin sulphate proteoglycan (CSPG) was also observed. The obtained results have shown that the scar formation is accompanied by quantitative and qualitative alterations in GAGs/PGs resembling those observed in hypertrophic skin scars. The biochemical modification of the scarred fascia lata may partly explain the clinically manifested damage to biomechanical properties of this tissue.

Glycosaminoglycans of human serum and their alterations in diabetes mellitus

Human serum contains several glycosaminoglycans (GAGs), mainly chondroitin sulphates and significantly less of heparan sulphate + heparin and dermatan sulphate. The non-insulin-dependent diabetes mellitus (with vascular complications) was associated with a significant increase in total serum GAG concentration, mainly of chondroitin sulphates and dermatan sulphate, with a simultaneous decrease in heparan sulphate + heparin level. These alterations were much more evident in patients with poor metabolic control. Hyaluronic acid (undetectable in healthy subjects and in patients with good metabolic control) appeared only in trace amounts in poorly controlled diabetic individuals. The obtained data allow to conclude that the diabetes mellitus-associated disturbances in tissue GAG metabolism lead to significant alterations in serum GAG composition.