Sera of children with renal tumours contain low-molecular-mass hyaluronic acid

Enzyme variants in biosynthesis and biological assessment of different molecular weight hyaluronan

In the present study, low- and high-molecular-weight hyaluronic acids (LMW-HA and HMW-HA) were synthesized in vitro by truncated Streptococcus equisimilis hyaluronan synthases (SeHAS). The enzyme kinetic parameters were determined for each enzyme variant. The MW, structure, dispersity, and biological activity of polymers were determined by electrophoresis, FTIR spectroscopy, carbazole, cell proliferation, and cell migration assay, respectively. The specific activities were calculated as 7.5, 6.8, 4.9, and 2.8 µgHA µgenzyme-1 min-1 for SeHAS, HAS123, HAS23, and HASIntra, respectively. The results revealed SeHAS produced a polydisperse HMW-HA (268 kDa), while HAS123 and HAS23 produced a polydisperse LMW-HA (< 30 kDa). Interestingly, HASIntra produced a low-disperse LMW-HA. Kinetics studies revealed the truncated variants displayed increased Km values for two substrates when compared to the wild-type enzyme. Biological assessments indicated all LMW-HAs showed a dose-dependent proliferation activity on endothelial cells (ECs), whereas HMW-HAs exhibited an inhibitory effect. Also, LMW-HAs had the highest cell migration effect at 10 µg/mL, while at 200 µg/mL, both LMW- and HMW-HAs postponed the healing recovery rate. The study elucidated that the transmembrane domains (TMDs) of SeHAS affect the enzyme kinetics, HA-titer, HA-size, and HA-dispersity. These findings open new insight into the rational engineering of SeHAS to produce size-defined HA.

Colorectal cancer-associated ~ 6 kDa hyaluronan serves as a novel biomarker for cancer progression and metastasis

Low molecular weight hyaluronan (LMW-HA) is believed to accumulate in tumors and to exert protumor effects. This study aimed to identify colorectal cancer (CRC)-associated LMW-HA, precisely determine its MW, and elucidate its role in predicting tumor progression. The MW distribution of HA extracted from CRC and paired noncancerous tissues was evaluated. We found that the level of HA with a MW below 30 kDa was markedly elevated in CRC tissues, and we defined HA with a MW of ~ 6 kDa as CRC-associated LMW-HA. In line with this finding, ~ 6 kDa HA was significantly accumulated in cancer tissues relative to total HA, and this LMW-HA played a critical role in tumor metastasis. Moreover, serum ~ 6 kDa HA levels in CRC patients were significantly increased and positively correlated with the levels in matched cancer tissues. Elevated serum ~ 6 kDa HA levels could be used to discriminate patients with or without CRC and was associated with early relapse, advanced tumor-node-metastasis stage, lymphovascular invasion, and lymph node (LN) metastasis. Notably, serum ~ 6 kDa HA levels were significantly reduced after tumor resection. Our study suggests that ~ 6 kDa HA may serve as a new biomarker for estimating tumor progression, predicting LN metastasis, and monitoring tumor recurrence.

Registration of the extracellular matrix components constituting the fibroblastic focus in idiopathic pulmonary fibrosis

The extracellular matrix (ECM) in idiopathic pulmonary fibrosis (IPF) drives fibrosis progression; however, the ECM composition of the fibroblastic focus (the hallmark lesion in IPF) and adjacent regions remains incompletely defined. Herein, we serially sectioned IPF lung specimens constructed into tissue microarrays and immunostained for ECM components reported to be deregulated in IPF. Immunostained sections were imaged, anatomically aligned, and 3D reconstructed. The myofibroblast core of the fibroblastic focus (defined by collagen I, α-smooth muscle actin, and procollagen I immunoreactivity) was associated with collagens III, IV, V, and VI; fibronectin; hyaluronan; and versican immunoreactivity. Hyaluronan immunoreactivity was also present at the fibroblastic focus perimeter and at sites where early lesions appear to be forming. Fibrinogen immunoreactivity was often observed at regions of damaged epithelium lining the airspace and the perimeter of the myofibroblast core but was absent from the myofibroblast core itself. The ECM components of the fibroblastic focus were distributed in a characteristic and reproducible manner in multiple patients. This information can inform the development of high-fidelity model systems to dissect mechanisms by which the IPF ECM drives fibrosis progression.

Hyaluronan and Hyaluronan Fragments

The glycosaminoglycan hyaluronan (HA) is a key component of the microenvironment surrounding cells. In healthy tissues, HA molecules have extremely high molecular mass and consequently large hydrodynamic volumes. Tethered to the cell surface by clustered receptor proteins, HA molecules crowd each other, as well as other macromolecular species. This leads to severe nonideality in physical properties of the biomatrix, because steric exclusion leads to an increase in effective concentration of the macromolecules. The excluded volume depends on both polymer concentration and hydrodynamic volume/molecular mass. The biomechanical properties of the extracellular matrix, tissue hydration, receptor clustering, and receptor-ligand interactions are strongly affected by the presence of HA and by its molecular mass. In inflammation, reactive oxygen and nitrogen species fragment the HA chains. Depending on the rate of chain degradation relative to the rates of new synthesis and removal of damaged chains, short fragments of the HA molecules can be present at significant levels. Not only are the physical properties of the extracellular matrix affected, but the HA fragments decluster their primary receptors and act as endogenous danger signals. Bioanalytical methods to isolate and quantify HA fragments have been developed to determine profiles of HA content and size in healthy and diseased biological fluids and tissues. These methods have potential use in medical diagnostic tests. Therapeutic agents that modulate signaling by HA fragments show promise in wound healing and tissue repair without fibrosis.

TGF-β1 Is Present at High Levels in Wound Fluid from Breast Cancer Patients Immediately Post-Surgery, and Is Not Increased by Intraoperative Radiation Therapy (IORT)

In patients with low-risk breast cancer, intraoperative radiotherapy (IORT) during breast-conserving surgery is a novel and convenient treatment option for delivering a single high dose of irradiation directly to the tumour bed. However, edema and fibrosis can develop after surgery and radiotherapy, which can subsequently impair quality of life. TGF- β is a strong inducer of the extracellular matrix component hyaluronan (HA). TGF-β expression and HA metabolism can be modulated by irradiation experimentally, and are involved in edema and fibrosis. We therefore hypothesized that IORT may regulate these factors.Wound fluid (WF) draining from breast lumpectomy sites was collected and levels of TGF-β1 and HA were determined by ELISA. Proliferation and marker expression was analyzed in primary lymphatic endothelial cells (LECs) treated with recombinant TGF-β or WF. Our results show that IORT does not change TGF-β1 or HA levels in wound fluid draining from breast lumpectomy sites, and does not lead to accumulation of sHA oligosaccharides. Nevertheless, concentrations of TGF-β1 were high in WF from patients regardless of IORT, at concentrations well above those associated with fibrosis and the suppression of LEC identity. Consistently, we found that TGF-β in WF is active and inhibits LEC proliferation. Furthermore, all three TGF-β isoforms inhibited LEC proliferation and suppressed LEC marker expression at pathophysiologically relevant concentrations.

Given that TGF-β contributes to edema and plays a role in the regulation of LEC identity, we suggest that inhibition of TGF-β directly after surgery might prevent the development of side effects such as edema and fibrosis.

Recapitulating the Size and Cargo of Tumor Exosomes in a Tissue-Engineered Model

There is a growing interest in the pivotal role of exosomes in cancer and in their use as biomarkers. However, despite the importance of the microenvironment for cancer initiation and progression, monolayer cultures of tumor cells still represent the main in vitro source of exosomes. As a result, their environmental regulation remains largely unknown. Here, we report a three-dimensional tumor model for studying exosomes, using Ewing's sarcoma type 1 as a clinically relevant example. The bioengineered model was designed based on the hypothesis that the 3-dimensionality, composition and stiffness of the tumor matrix are the critical determinants of the size and cargo of exosomes released by the cancer cells. We analyzed the effects of the tumor microenvironment on exosomes, and the effects of exosomes on the non-cancer cells from the bone niche. Exosomes from the tissue-engineered tumor had similar size distribution as those in the patients' plasma, and were markedly smaller than those in monolayer cultures. Bioengineered tumors and the patients' plasma contained high levels of the Polycomb histone methyltransferase EZH2 mRNA relatively to their monolayer counterparts. Notably, EZH2 mRNA, a potential tumor biomarker detectable in blood plasma, could be transferred to the surrounding mesenchymal stem cells. This study provides the first evidence that an in vitro culture environment can recapitulate some properties of tumor exosomes.

Key Roles of Hyaluronan and Its CD44 Receptor in the Stemness and Survival of Cancer Stem Cells

Cancer stem cells (CSCs) represent a unique subpopulation of self-renewing oncogenic cells that drive cancer initiation and progression. CSCs often acquire multidrug and oxidative stress resistance and are thereby thought to be responsible for tumor recurrence following treatment and remission. Although the mechanisms responsible for CSC generation, maintenance, and expansion have become a major focus in cancer research, the molecular characteristics of CSCs remain poorly understood. The stemness and subsequent expansion of CSCs are believed to be highly influenced by changes in microenvironmental signals as well as genetic and epigenetic alterations. Hyaluronan (HA), a major component of the extracellular matrix, has recently been demonstrated to provide a favorable microenvironment for the self-renewal and maintenance of stem cells. HA directly and indirectly affects CSC self-renewal by influencing the behavior of both cancer and stromal cells. For instance, HA in the tumor microenvironment modulates the function of tumor-associated macrophages to support CSC self-renewal, and excessive HA production promotes the acquisition of CSC signatures through epithelial-to-mesenchymal transition. The importance of HA in mediating CSC self-renewal has been strengthened by the finding that interactions between HA and its receptor, CD44, propagate the stemness of CSCs. HA–CD44 interactions evoke a wide range of signals required for CSC self-renewal and maintenance. CD44 also plays a critical role in the preservation and multidrug resistance (MDR) of CSCs by transmitting survival and anti-apoptotic signals. Thus, a better understanding of the molecular mechanisms involved in HA and CD44 control of CSC stemness may help in the design of more effective therapies for cancer patients. In this review, we address the key roles of HA and CD44 in CSC self-renewal and maintenance. We also discuss the involvement of CD44 in the oxidative stress and MDR of CSCs.

Sugars in the microenvironment: the sticky problem of HA turnover in tumors

The properties and behavior of tumor cells are closely regulated by their microenvironment. Accordingly, stromal cells and extracellular matrix components can have a pronounced effect on cancer initiation, growth, and progression. The linear glycosaminoglycan hyaluronan (HA) is a major component of the extracellular matrix. Altered synthesis and degradation of HA in the tumor context has been implicated in many aspects of tumor biology. In particular, the accumulation of small HA oligosaccharides (sHA) in the tumor interstitial space may play a decisive role, due to the ability of sHA to activate a number of biological processes that are not modulated by high molecular weight (HMW)-HA. In this article, we review the normal physiological role and metabolism of HA and then survey the evidence implicating HA in tumor growth and progression, focusing in particular on the potential contribution of sHA to these processes.

The Content and Size of Hyaluronan in Biological Fluids and Tissues

Hyaluronan is a simple repeating disaccharide polymer, synthesized at the cell surface by integral membrane synthases. The repeating sequence is perfectly homogeneous, and is the same in all vertebrate tissues and fluids. The polymer molecular mass is more variable. Most commonly, hyaluronan is synthesized as a high-molecular mass polymer, with an average molecular mass of approximately 1000–8000 kDa. There are a number of studies showing increased hyaluronan content, but reduced average molecular mass with a broader range of sizes present, in tissues or fluids when inflammatory or tissue-remodeling processes occur. In parallel studies, exogenous hyaluronan fragments of low-molecular mass (generally, <200 kDa) have been shown to affect cell behavior through binding to receptor proteins such as CD44 and RHAMM (gene name HMMR), and to signal either directly or indirectly through toll-like receptors. These data suggest that receptor sensitivity to hyaluronan size provides a biosensor of the state of the microenvironment surrounding the cell. Sensitive methods for isolation and characterization of hyaluronan and its fragments have been developed and continue to improve. This review provides an overview of the methods and our current state of knowledge of hyaluronan content and size distribution in biological fluids and tissues.

Targeting hyaluronic acid family for cancer chemoprevention and therapy

Hyaluronic acid or hyaluronan (HA) is perhaps one of the most uncomplicated large polymers that regulates several normal physiological processes and, at the same time, contributes to the manifestation of a variety of chronic and acute diseases, including cancer. Members of the HA signaling pathway (HA synthases, HA receptors, and HYAL-1 hyaluronidase) have been experimentally shown to promote tumor growth, metastasis, and angiogenesis, and hence each of them is a potential target for cancer therapy. Furthermore, as these members are also overexpressed in a variety of carcinomas, targeting of the HA family is clinically relevant. A variety of targeted approaches have been developed to target various HA family members, including small-molecule inhibitors and antibody and vaccine therapies. These treatment approaches inhibit HA-mediated intracellular signaling that promotes tumor cell proliferation, motility, and invasion, as well as induction of endothelial cell functions. Being nontoxic, nonimmunogenic, and versatile for modifications, HA has been used in nanoparticle preparations for the targeted delivery of chemotherapy drugs and other anticancer compounds to tumor cells through interaction with cell-surface HA receptors. This review discusses basic and clinical translational aspects of targeting each HA family member and respective treatment approaches that have been described in the literature.

A novel role of low molecular weight hyaluronan in breast cancer metastasis

Low molecular weight hyaluronan (LMW-HA), a degradation fragment of the extracellular matrix component hyaluronan (HA), has been proven to play a crucial role in cancer progression. However, no systematic clinical study of breast cancer has been performed to correlate LMW-HA levels with metastasis. In the present study, we analyzed 176 serum specimens and found for the first time that the serum LMW-HA (but not total HA) level significantly correlated with lymph node metastasis, suggesting that serum LMW-HA represents a better prognostic indicator of breast cancer progression than HA. Similarly, we found that breast cancer cell lines displaying higher invasive potential had a higher LMW-HA concentration than less-invasive cell lines. This higher LMW-HA level was accompanied by the overexpression of hyaluronan synthase (HAS2) and hyaluronidase (both HYAL1 and HYAL2). Of great importance, decreasing LMW-HA production significantly inhibited breast cancer cell migration and invasion. Overall, our results suggest that during cancer progression, cancer cells may actively remodel their microenvironment via an autocrine/paracrine-like process, resulting in elevated LMW-HA levels, which in turn may facilitate cancer progression by promoting the migration and invasion of cancer cells. Therefore, cancer-associated LMW-HA may be a more promising molecular biomarker than total HA for detecting metastasis and may have further applications in breast cancer treatment.

Biological functions of hyaluronan and cytokine-inducible deubiquitinating enzymes

The modification of proteins through post-translation and degradation by the ubiquitin-proteasome system plays a pivotal role in a broad array of biological processes. Reversal of this process by deubiquitination is a central step in the maintenance and regulation of cellular homeostasis. It now appears that the regulation of ubiquitin pathways by deubiquitinating enzymes (DUBs) could be used as targets for anticancer therapy. Recent success in inducing apoptosis in cancerous cells by USP17, a cytokine-inducible DUB encoding two hyaluronan binding motifs (HABMs) showing direct interaction with hyaluronan (HA), could prove a promising step in the development of DUBs containing HABMs as agents in anticancer therapeutics. In this review, we summarize the importance of hyaluronan (HA) in cancer, the role played by DUBs in apoptosis, and a possible relationship between DUBs and HA in cancerous cells, suggesting new strategies for applying DUB enzymes as potential anticancer therapeutics.

Accumulation of small hyaluronan oligosaccharides in tumour interstitial fluid correlates with lymphatic invasion and lymph node metastasis

BACKGROUND

Association studies have implicated the glycosaminoglycan hyaluronan (hyaluronic acid, HA) and its degrading enzymes the hyaluronidases in tumour progression and metastasis. Oligosaccharides of degraded HA have been ascribed a number of biological functions that are not exerted by high-molecular-weight HA (HMW-HA). However, whether these small HA oligosaccharides (sHA) have a role in tumour progression currently remains uncertain due to an inability to analyse their concentration in tumours.

METHODS

We report a novel method to determine the concentration of sHA ranging from 6 to 25 disaccharides in tumour interstitial fluid (TIF). Levels of sHA were measured in TIF from experimental rat tumours and human colorectal tumours.

RESULTS

While the majority of HA in TIF is HMW-HA, concentrations of sHA up to 6 μg ml(-1) were detected in a subset of tumours, but not in interstitial fluid from healthy tissues. In a cohort of 72 colorectal cancer patients we found that increased sHA concentrations in TIF are associated with lymphatic vessel invasion by tumour cells and the formation of lymph node metastasis.

CONCLUSIONS

These data document for the first time the pathophysiological concentration of sHA in tumours, and provide evidence of a role for sHA in tumour progression.

Low molecular weight hyaluronan induces lymphangiogenesis through LYVE-1-mediated signaling pathways

Hyaluronan (HA), a large nonsulfated glycosaminogycan in the extracellular matrix, whose degraded fragments termed as low molecular weight hyaluronan (LMW-HA), has been reported as an important regulator of angiogenesis. However, little is known about the influence of LMW-HA on lymphangiogenesis. In this study, we try to explore the in vitro effects of LMW-HA on lymphangiogenesis and identify the underlying molecular mechanisms. Our results showed that LMW-HA stimulation significantly increased lymphatic endothelial cells (LECs) proliferation, migration and tube formation. Further experiments demonstrated that LMW-HA altered actin cytoskeleton rearrangement and increased the formation of intense stress fibers, lamellipodia and filopodia. Mechanistically, LMW-HA stimulation resulted in rapid tyrosine phosphorylation of protein kinase C α/βII (PKCα/βII) and extracellular-regulated kinase 1/2 (ERK1/2). Lymphalic vessel endotheilial hyaluronan receptor 1 (LYVE-1), a homologue of CD44, is the main cell surface receptor for HA in LECs. Blocking the binding interaction of LMW-HA with LYVE-1 using neutralizing anti-LYVE-1 antibodies significantly inhibited LECs proliferation, migration, tube formation and signal transduction induced by LMW-HA, suggesting that LMW-HA may play a critical role in the processes required for lymphangiogenesis through interactions with its receptor LYVE-1 and triggering intracellular signal cascades.

Development of a novel metastatic breast cancer score based on hyaluronic acid metabolism

Tumor metastasis involves the dissemination of malignant cells into the basement membrane, and the vascular system contributes to the circulating pool of these markers. In this context, our aim has been focused on the development of a non-invasive score based on degradation of the backbone of glycosaminoglycans of the extracellular matrix; namely hyaluronic acid (HA), for the assessment of metastasis in patients with breast cancer. HA level was determined by enzyme-linked immunosorbent assay; CA 15.3 was determined by microparticle enzyme immunoassay; hyaluronidase, N-acetyl-β-D-glucosaminidase, β-glucuronidase, glucuronic acid, and glucosamine were assayed by standard colorimetric techniques in 217 patients with breast cancer. Statistical analyses were performed by logistic regression and receiver-operating characteristic analysis curves. The multivariate discriminant analysis selects a score based on absolute values of the six biochemical markers: metastatic breast cancer score (MBCS) = [1.04 (Numerical constant) + 0.003 × CA 15.3 (U/l) + 0.001 × HA (ng/ml) + 0.004 × hyaluronidase (mg N-acetyl-β-D-glucosamine/ml/18 h) + 0.001 × N-acetyl-β-D-glucosaminidase (μmol/ml/min) + 0.026 × glucuronic acid (ng/ml) + 0.003 × glucosamine (μg/dl)]. This function correctly classified 87 % of metastatic breast cancer at cut-off value = 0.85 (i.e., great than 0.85 indicates patients with metastatic breast cancer and less than 0.85 indicates patients with non-metastatic breast cancer). MBCS is a novel, non-invasive, and simple score which can be applied to discriminate patients with metastatic breast cancer.

The significance of serum levels of adiponectin, leptin, and hyaluronic acid in hepatocellular carcinoma of cirrhotic and noncirrhotic patients

It is well established that hepatocellular carcinoma (HCC) develops in a multistep process, from chronic hepatitis, cirrhosis to HCC. Adipose tissue is not simply an energy storage organ but also a secretory organ, producing a variety of bioactive molecules known as adipokines, including adiponectin and leptin. Hyaluronic acid (HA) is an extracellular matrix protein, often associated with a variety of human cancers. Our retrospective study determines serum levels of adiponectin, leptin, and HA in HCC of cirrhotic and noncirrhotic patients and compares these levels to patients with cirrhosis and normal subjects. Noncirrhotic HCC (n = 19), cirrhotic HCC (n = 50), cirrhosis (n = 36) patients and twenty one age-, sex-, and body mass index (BMI)-matched normal healthy controls were subjected in the present study. Serum adiponectin, leptin, and HA levels were determined using enzyme-linked immunosorbent assay technique. Levels of serum adiponectin were significantly higher in the cirrhosis and cirrhotic HCC groups than in the normal subjects, whereas serum HA levels were found to significantly increase in all three patients groups. The elevation of serum leptin in our HCC patients, regardless of being cirrhotic or noncirrhotic, but not in the patients with cirrhosis, may shed some light on the significance of serum leptin level in HCC. Further studies are recommended to evaluate the prognostic value of serum leptin level in HCC.

Serum hyaluronic acid and laminin as potential tumor markers for upper gastrointestinal cancers

BACKGROUND

Early diagnosis of patients with upper gastrointestinal cancer is important because many cases are diagnosed in advanced stages and have poor prognosis. Several studies have reported increased serum levels of hyaluronic acid and laminin in various cancers and the correlation of the levels with poor prognosis. However, little data on the use of serum hyaluronic acid and laminin levels for early detection of esophageal and gastric cancers are available.

METHODS

We assessed serum hyaluronic acid and laminin levels using enzyme-linked immunosorbent assay in 20 gastric cardia cancer, 23 gastric noncardia cancer and 20 esophageal squamous cell carcinoma incident cases and 25 controls in the Golestan Province, northern Iran, a high risk area for upper gastrointestinal cancers.

RESULTS

Mean serum hyaluronic acid and laminin concentrations in cancer cases were higher than in controls in crude analyses. Significant correlations were observed between hyaluronic acid levels and gastric noncardia cancer (Beta-coefficient=0.390; P=0.01) and esophageal squamous cell carcinoma (Beta-coefficient=0.332; P=0.05) and between laminin levels and gastric cardia cancer (Beta-coefficient=0.454; P=0.003) in multivariate models. For esophageal squamous cell carcinoma, gastric cardia cancer, and gastric noncardia cancer, area under ROC curve (AUC) of hyaluronic acid was 0.708, 0.694, and 0.770, and of laminin was 0.706, 0.828, and 0.671.

CONCLUSIONS

Our study suggests that hyaluronic acid and laminin may be used to identify potentially high-risk groups of upper gastrointestinal cancers for further diagnostic work-ups, particularly in high incidence areas. Nevertheless, further studies with larger sample size and tumor staging information are warranted to clarify the clinical significance of hyaluronic acid and laminin in those cancers.

Smart nanocarrier based on PEGylated hyaluronic acid for cancer therapy

Tumor targetability and site-specific drug release of therapeutic nanoparticles are key factors for effective cancer therapy. In this study, poly(ethylene glycol) (PEG)-conjugated hyaluronic acid nanoparticles (P-HA-NPs) were investigated as carriers for anticancer drugs including doxorubicin and camptothecin (CPT). P-HA-NPs were internalized into cancer cells (SCC7 and MDA-MB-231) via receptor-mediated endocytosis, but were rarely taken up by normal fibroblasts (NIH-3T3). During in vitro drug release tests, P-HA-NPs rapidly released drugs when incubated with cancer cells, extracts of tumor tissues, or the enzyme Hyal-1, which is abundant in the intracellular compartments of cancer cells. CPT-loaded P-HA-NPs (CPT-P-HA-NPs) showed dose-dependent cytotoxicity to cancer cells (MDA-MB-231, SCC7, and HCT 116) and significantly lower cytotoxicity against normal fibroblasts (NIH-3T3) than free CPT. Unexpectedly, high concentrations of CPT-P-HA-NPs demonstrated greater cytotoxicity to cancer cells than free CPT. An in vivo biodistribution study indicated that P-HA-NPs selectively accumulated into tumor sites after systemic administration into tumor-bearing mice, primarily due to prolonged circulation in the blood and binding to a receptor (CD44) that was overexpressed on the cancer cells. In addition, when CPT-P-HA-NPs were systemically administrated into tumor-bearing mice, we saw no significant increases in tumor size for at least 35 days, implying high antitumor activity. Overall, P-HA-NPs showed promising potential as a drug carrier for cancer therapy.

Hyaluronic acid-based nanocarriers for intracellular targeting: interfacial interactions with proteins in cancer

The therapeutic efficacy of most drugs is greatly depends on their ability to cross the cellular barrier and reach their intracellular target sites. To transport the drugs effectively through the cellular membrane and to deliver them into the intracellular environment, several interesting smart carrier systems based on both synthetic or natural polymers have been designed and developed. In recent years, hyaluronic acid (HA) has emerged as a promising candidate for intracellular delivery of various therapeutic and imaging agents because of its innate ability to recognize specific cellular receptors that overexpressed on diseased cells. The aim of this review is to highlight the significance of HA in cancer, and to explore the recent advances of HA-based drug carriers towards cancer imaging and therapeutics.

Involvement of hyaluronidases in colorectal cancer

BACKGROUND

Hyaluronidases belong to a class of enzymes that degrade, predominantly, hyaluronan. These enzymes are known to be involved in physiological and pathological processes, such as tumor growth, infiltration and angiogenesis, but their exact role in tumor promotion or suppression is not clear yet. Advanced colorectal cancer is associated with elevated amounts of hyaluronan of varying size. The aim of the present study was therefore to illuminate the importance of hyaluronidases in colon carcinoma progression.

METHODS

The patients' samples (macroscopically normal and cancerous) were subjected to sequential extraction with PBS, 4 M GdnHCl and 4 M GdnHCl --1% Triton X-100. The presence of the various hyaluronidases in the extracts was examined by zymography and western blotting. Their expression was also examined by RT-PCR.

RESULTS

Among hyaluronidases examined, Hyal-1, -2, -3 and PH-20 were detected. Their activity was higher in cancerous samples. Hyal-1 and Hyal-2 were overexpressed in cancerous samples, especially in advanced stages of cancer. Both isoforms were mainly extracted with PBS. Hyal-3 was observed only in the third extract of advanced stages of cancer. PH-20 was abundant in all three extracts of all stages of cancer. The expression of only Hyal-1 and PH-20 was verified by RT-PCR.

CONCLUSION

A high association of hyaluronidases in colorectal cancer was observed. Each hyaluronidase presented different tissue distribution, which indicated the implication of certain isoforms in certain cancer stages. The results provided new evidence on the mechanisms involved in the progression of colorectal cancer.

Final report of the safety assessment of hyaluronic acid, potassium hyaluronate, and sodium hyaluronate

Hyaluronic acid, sodium hyaluronate, and potassium hyaluronate function in cosmetics as skin conditioning agents at concentrations up to 2%. Hyaluronic acid, primarily obtained from bacterial fermentation and rooster combs, does penetrate to the dermis. Hyaluronic acid was not toxic in a wide range of acute animal toxicity studies, over several species and with different exposure routes. Hyaluronic acid was not immunogenic, nor was it a sensitizer in animal studies. Hyaluronic acid was not a reproductive or developmental toxicant. Hyaluronic acid was not genotoxic. Hyaluronic acid likely does not play a causal role in cancer metastasis; rather, increased expression of hyaluronic acid genes may be a consequence of metastatic growth. Widespread clinical use of hyaluronic acid, primarily by injection, has been free of significant adverse reactions. Hyaluronic acid and its sodium and potassium salts are considered safe for use in cosmetics as described in the safety assessment.

Role of hyaluronan in glioma invasion

Gliomas are the most common primary intracranial tumors. Their distinct ability to infiltrate into the extracellular matrix (ECM) of the brain makes it impossible to treat these tumors using surgery and radiation therapy. A number of different studies have suggested that hyaluronan (HA), the principal glycosaminoglycan (GAG) in the ECM of the brain, is the critical factor for glioma invasion. HA-induced glioma invasion was driven by two important molecular events: matrix metalloproteinase (MMP) secretion and up-regulation of cell migration. MMP secretion was triggered by HA-induced focal adhesion kinase (FAK) activation, which transmits its signal through ERK activation and nuclear factor kappa B (NF-kappaB) translocation. Another important molecular event is osteopontin (OPN) expression. OPN expression by AKT activation triggers cell migration. These results suggest that HA-induced glioma invasion is tightly regulated by signaling mechanisms, and a detailed understanding of this molecular mechanism will provide important clues for glioma treatment.

Hyaluronan and hyaluronidase in genitourinary tumors

Genitourinary cancers are the most frequently diagnosed cancers in men and the fifth most common in women. Management of disease through accurate and cost effective early diagnostic markers, as well as identification of valid prognostic indicators, has contributed significantly to improved treatment outcomes. In this review, we will discuss the function, regulation and clinical utility of hyaluronan (HA), genes encoding its metabolic enzymes and receptors that mediate its cellular effects. Specific HA synthase (HAS) and hyaluronidase (HAase) genes encode the enzymes that produce HA polymers and oligosaccharides, respectively. Differential effects of these enzymes in progression of genitourinary tumors are determined by the relative balance between HAS and HAase levels, as well as the distribution of receptors. The genes are regulated in a complex fashion at the transcriptional and post-translational levels, but also by epigenetic events, alternative mRNA splicing, and subcellular localization. Importantly, the major tumor-derived HAase enzyme, HYAL-1, either alone or together with HA, is an accurate diagnostic and prognostic marker for genitourinary tumors.

Hyaluronidases in cancer biology

Hyaluronan is a megadalton glycosaminoglycan polymer critical for maintaining the integrity of the extracellular matrix. It can exist in a protein-bound state with aggregating proteoglycans, where it expands the extracellular matrix and modulates cell-cell interactions. It also exists in lower molecular weight forms that participate in a myriad of biological functions. It is unique in that much of it is degraded within hours of its synthesis. High molecular weight hyaluronan, a reflection of intact healthy tissues, is normally produced by hyaluronan synthases at the plasma membrane. It is catabolized by the action of an extracellular plasma membrane-tethered hyaluronidase that is coordinated with intracellular lysosomal hyaluronidases and exoglycosidases. This occurs in local tissues and lymph, with the remainder being cleared by the sinusoidal liver endothelium upon entering the vascular compartment. Elevated extracellular levels of hyaluronan and its partially catabolized oligomers are found in certain malignancies, potentially due to decoupled synthesis and degradation. Furthermore, partially depolymerized hyaluronan in the extracellular environment may have properties not found in the multivalent high molecular weight polymer in malignancies. Functional perturbations of hyaluronan synthesis and degradation have revealed active roles of the synthases and hyaluronidases in epithelial mesenchymal conversion, stroma and vascular formation, interstitial fluid pressure and chemosensitivity. While at least three confirmed hyaluronidases exist in the human genome (HYAL1, HYALl2 and PH20), functional perturbation of these genes in mice have failed to identify a simple linear catabolic circuit. The family of enzymes responsible for the synthesis and degradation of hyaluronan are being characterized. The fragmented forms of hyaluronan, largely a sign of cellular distress, occur in abundance in many malignancies. These small hyaluronan oligomers are assumed to be largely a result of hyaluronidase activity. Precisely how particular-sized fragments are generated and maintained is not known. Presumably, hyaluronan-binding proteins, in addition to the proteoglycans, participate in this process. Hyaluronidase inhibitors are now recognized, as well as growth factors that enhance the synthetic enzymes. A complete understanding of the anabolic and catabolic systems for hyaluronan may provide new dimensions into our understanding of cancer progression, as well as new opportunities for therapeutic intervention.

Hyaluronan fragments: an information-rich system

Hyaluronan is a straight chain, glycosaminoglycan polymer of the extracellular matrix composed of repeating units of the disaccharide [-D-glucuronic acid-beta1,3-N-acetyl-D-glucosamine-beta1,4-]n. Hyaluronan is synthesized in mammals by at least three synthases with products of varying chain lengths. It has an extraordinary high rate of turnover with polymers being funneled through three catabolic pathways. At the cellular level, it is degraded progressively by a series of enzymatic reactions that generate polymers of decreasing sizes. Despite their exceedingly simple primary structure, hyaluronan fragments have extraordinarily wide-ranging and often opposing biological functions. There are large hyaluronan polymers that are space-filling, anti-angiogenic, immunosuppressive, and that impede differentiation, possibly by suppressing cell-cell interactions, or ligand access to cell surface receptors. Hyaluronan chains, which can reach 2 x 10(4) kDa in size, are involved in ovulation, embryogenesis, protection of epithelial layer integrity, wound repair, and regeneration. Smaller polysaccharide fragments are inflammatory, immuno-stimulatory and angiogenic. They can also compete with larger hyaluronan polymers for receptors. Low-molecular-size polymers appear to function as endogenous "danger signals", while even smaller fragments can ameliorate these effects. Tetrasaccharides, for example, are anti-apoptotic and inducers of heat shock proteins. Various fragments trigger different signal transduction pathways. Particular hyaluronan polysaccharides are also generated by malignant cells in order to co-opt normal cellular functions. How the small hyaluronan fragments are generated is unknown, nor is it established whether the enzymes of hyaluronan synthesis and degradation are involved in maintaining proper polymer sizes and concentration. The vast range of activities of hyaluronan polymers is reviewed here, in order to determine if patterns can be detected that would provide insight into their production and regulation.

Tumor cells enhance their own CD44 cleavage and motility by generating hyaluronan fragments

Hyaluronan (HA) is an extracellular matrix glycosaminoglycan that interacts with cell-surface receptors, including CD44. Although HA usually exists as a high molecular mass polymer, HA of a much lower molecular mass that shows a variety of biological activities can be detected under certain pathological conditions, particularly in tumors. We previously reported that low molecular weight HAs (LMW-HAs) of a certain size range induce the proteolytic cleavage of CD44 from the surface of tumor cells and promote tumor cell migration in a CD44-dependent manner. Here, we show that MIA PaCa-2, a human pancreatic carcinoma cell line, secreted hyaluronidases abundantly and generated readily detectable levels of LMW-HAs ranging from approximately 10- to 40-mers. This occurred in the absence of any exogenous stimulation. The tumor-derived HA oligosaccharides were able to enhance CD44 cleavage and tumor cell motility. Inhibition of the CD44-HA interaction resulted in the complete abrogation of these cellular events. These results are consistent with the concept that tumor cells generate HA oligosaccha-rides that bind to tumor cell CD44 through the expression of their own constitutive hyaluronidases. This enhances their own CD44 cleavage and cell motility, which would subsequently promote tumor progression. Such an autocrine/paracrine-like process may represent a novel activation mechanism that would facilitate and promote the malignant potential of tumor cells.

Chemotaxis towards hyaluronan is dependent on CD44 expression and modulated by cell type variation in CD44-hyaluronan binding

The accumulation of the extracellular matrix glycosaminoglycan hyaluronan by tumours and tumour-associated stroma promotes cancer cell invasion and metastasis. Using the Dunn chamber chemotaxis assay, we demonstrate for the first time that high molecular mass hyaluronan acts as a soluble chemoattractant promoting the directional migration of MDA-MB-468 and MDA-MB-231 breast cancer cells. Moreover, chemotaxis towards hyaluronan, but not foetal bovine serum, can be abrogated following treatment of the cells with siRNA oligonucleotides to downregulate CD44 expression. These data indicate that CD44 is the principal receptor mediating this response and that CD44 expression is not a general requirement for cell migration and gradient sensing, rather it elicits a ligand-specific response. However, expression of CD44 alone is not sufficient to drive chemotaxis towards hyaluronan, as NIH-3T3 fibroblasts were unable to respond to a hyaluronan gradient even when transfected with high levels of human CD44. For NIH-3T3 cells to bind exogenous hyaluronan, it was necessary to both increase the level of receptor expression and remove a hyaluronan pericellular matrix. Together, these studies reveal a direct mechanism for promoting cell invasion into the hyaluronan-rich matrix and predict that in the complex multicellular environment in vivo, multiple mechanisms exist to regulate the ability of a cell to respond to a chemotactic hyaluronan gradient.

Hyaluronan-oligosaccharide-induced transcription of metalloproteases

Activated dendritic epidermal Langerhans cells and metastatic tumour cells share many properties. Both cell types can invade the surrounding tissue, enter the lymphatic system and travel to regional lymph nodes. We have recently shown that fragments of the extracellular matrix component hyaluronan, which are typically produced at sites of inflammation, can activate dendritic cells. Upon activation, dendritic cells upregulate expression of matrix metalloproteases (MMPs). These observations prompted us to investigate whether exposure to hyaluronan fragments also induces MMP expression in tumour cells. Here, we report that MMP-9, MMP-13 and urokinase plasminogen activator are upregulated in murine 3LL tumour cells after exposure to mixed-size hyaluronan. Similarly upregulated MMP-9 and MMP-13 expression was observed in primary fibroblasts. By using size-fractionated hyaluronan preparations, we show that the enhanced expression of MMP-9 and MMP-13 is only induced by small hyaluronan (HA) fragments. Although our data suggest that HA-fragment-induced MMP-9 and MMP-13 expression is receptor mediated, they rule out an involvement of the hyaluronan receptors CD44, RHAMM/IHAP and TLR-4. Finally, we show that HA fragment-induced MMP-9 transcription is mediated via NF-κB. Our results suggest that the metastasis-associated HA degradation in tumours might promote invasion by inducing MMP expression.

Hyaluronan oligosaccharides induce CD44 cleavage and promote cell migration in CD44-expressing tumor cells

CD44 is an adhesion molecule that serves as a cell surface receptor for several extracellular matrix components, including hyaluronan (HA). The proteolytic cleavage of CD44 from the cell surface plays a critical role in the migration of tumor cells. Although this cleavage can be induced by certain stimuli such as phorbol ester and anti-CD44 antibodies in vitro, the physiological inducer of CD44 cleavage in vivo is unknown. Here, we demonstrate that HA oligosaccharides of a specific size range induce CD44 cleavage from tumor cells. Fragmented HA containing 6-mers to 14-mers enhanced CD44 cleavage dose-dependently by interacting with CD44, whereas a large polymer HA failed to enhance CD44 cleavage, although it bound to CD44. Examination using uniformly sized HA oligosaccharides revealed that HAs smaller than 36 kDa significantly enhanced CD44 cleavage. In particular, the 6.9-kDa HA (36-mers) not only enhanced CD44 cleavage but also promoted tumor cell motility, which was completely inhibited by an anti-CD44 monoclonal antibody. These results raise the possibility that small HA oligosaccharides, which are known to occur in various tumor tissues, promote tumor invasion by enhancing the tumor cell motility that may be driven by CD44 cleavage.

Hyaluronan is not elevated in urine or serum in Hutchinson-Gilford Progeria Syndrome

Elevations in urinary hyaluronan have been used as the principal laboratory indicator for diagnosis of Hutchinson-Gilford Progeria Syndrome (HGPS). Previous reports have provided evidence suggesting that children with HGPS have altered hyaluronan metabolism as indicated by a mean 17-fold increase in urinary hyaluronan over normal values. In addition, adults with Werner's syndrome have elevated urinary hyaluronan and even more prominent elevations in serum hyaluronan over age-matched controls. It is not known whether serum hyaluronan is elevated or whether serum hyaluronan levels correlate with urinary hyaluronan levels in children with HGPS. In a large cohort of 19 HGPS patients, we sought to confirm elevations in urinary hyaluronan concentration, to establish whether serum hyaluronan is elevated, to measure the size of urinary hyaluronan, and to determine whether serum or urine hyaluronidase levels are altered. We have analyzed urinary and serum hyaluronan levels in patients with HGPS and control patients (1) by using an enzyme-linked immunosorbent assay (ELISA)-like method in which sample hyaluronan in solution and hyaluronan in solid phase compete for a solution of biotinylated hyaluronan-binding protein, and (2) by fluorophore-assisted carbohydrate electrophoresis. The size of urinary hyaluronan was measured by using Sepharose CL-6B size exclusion chromatography. Serum and urinary hyaluronidases were evaluated quantitatively, by using ELISA, and qualitatively, by using a gel detection method. HGPS patients did not show a significant elevation in either urinary or serum hyaluronan. We detected no difference in the size of urinary hyaluronan between HGPS children and age-matched controls. Serum and urinary hyaluronidase levels were not significantly different in normal and HGPS patients. These studies indicate that neither serum nor urinary hyaluronan concentration is a reliable diagnostic or prognostic marker for HGPS and underscore a difference between adult and childhood progerias.

Serum creatine kinase levels parallel the clinical course for rhabdomyomatous Wilms tumor

A right-sided renal mass in an 11-month-old girl was diagnosed by percutaneous needle biopsy as Wilms tumor, which on histologic examination was found to be predominantly rhabdomyomatous. As part of the examination, serum creatine kinase (CK) and CK-MB levels were measured and were significantly elevated at 994 U/L (reference range, 42-180 U/L) and 40 U/L (reference range, 0-3 U/L), respectively. Subsequently, an 8-month-old girl was admitted to the hospital with septicemia and was found to have an abdominal mass. A diagnosis of bilateral Wilms tumor was made following percutaneous biopsy of both kidneys; histologic examination confirmed that the tumor was predominantly rhabdomyomatous. Serum CK and CK-MB levels also were measured and were significantly elevated at 685 U/L and 84.4 U/L, respectively. In both cases, the serum CK and CK-MB levels reflected the clinical course; elevation in serum levels was associated with tumor recurrence, infarction, or chemotherapy-related necrosis. We conclude that these enzymes have clinical usefulness as markers for Wilms tumor showing rhabdomyomatous morphologic features.

Fibrotic healing of adult and late gestation fetal wounds correlates with increased hyaluronidase activity and removal of hyaluronan

The lack of scarring and fibrosis in healing fetal skin wounds may relate to a prolonged presence of hyaluronan (HA). It has been suggested that fetal wounds may lack hyaluronidase, but the hyaluronidase levels in fetal wounds remain unknown. The size of HA influences its biological action, especially in relation to angiogenesis, which is also reduced in fetal wound healing. The present study determined the levels and size of HA, as well as hyaluronidase levels, in fetal and adult lamb wounds. Wire mesh cylinders, or polyvinyl acetate sponges, were placed subcutaneously in fetal lambs at 75, 100 or 120 days gestation. Wound fluid and wound tissue were harvested 3, 7 or 14 days later. Samples were digested with papain and both HA and hyaluronidase activity were determined in a competitive ELISA assay. Size distribution of HA was estimated using a Sephacryl S1000 column and fractions were collected for HA determination. Adult wound fluid HA remained low (4-5 micrograms/ml) over the 14 days. Fetal fluids were similar on day 3, but increased to 15-25 micrograms/ml by day 7. In 75/100-day wounds, HA remained elevated at 14 days, but in 120-day fluids decreased to levels similar to adult fluid. The HA in all fluids was polydisperse with a main peak at 200 kDa. Hyaluronidase levels were detected in all samples, reaching a peak 7 days post-wounding. In adult wound fluids hyaluronidase was much higher than the fetal wound fluids. These data suggest that lower hyaluronidase levels in fetal wounds may underlie the different pattern of HA deposition seen in fetal wounds.

The relationship between hyaluronidase activity and hyaluronic acid concentration in sera from normal controls and from patients with disseminated neoplasm

Serum hyaluronidase activity (HAE) and hyaluronic acid (HA) concentration were measured in sera from patients with disseminated neoplasm and compared to those of normal controls. The serum HAE activity in disseminated neoplasm (mean, 12.6 mumol N-acetylglucosamine (NAG)/min/1; range, 5.2-24.7 mumol NAG/min/1) was significantly lower (t = 6.7, p < 0.001) than in normal controls (mean, 17.1 mumol NAG/min/1; range, 11.5-27.0 mumol NAG/min/1). The serum HA concentration in patients with disseminated neoplasm (mean, 8199.7 micrograms/l; range, 42.0-496,000 micrograms/l) was significantly higher (t = 2.63, 0.01 > p> 0.001) than in normal age-matched controls (mean, 55.6 micrograms/l; range, 10.0-348.0 micrograms/l). A negative correlation was found between the serum HAE activity and the HA concentration (r = -0.45, t = 5.92, p < 0.001). The possible reasons for the low serum HAE activity and the raised serum HA concentration in patients with disseminated neoplasm and the negative correlation between the results are discussed.

Serum hyaluronan as a disease marker

Hyaluronan is a connective tissue polysaccharide which has also been found in blood serum in concentrations < 100 micrograms/L (average 30-40 micrograms/L in middle-aged persons). The serum level is regulated by the influx of the polysaccharide from the tissues via lymph and its receptor-mediated clearance by liver endothelial cells. Markedly high serum levels are noted in certain liver diseases, especially in patients with cirrhosis, when the clearance is impaired. In these cases serum hyaluronan can be used to follow the development of the disease. Serum hyaluronan is also a sensitive marker for impending rejection of liver transplants. Patients with rheumatoid arthritis constitute another major group with increased serum hyaluronan, but in this case the level varies markedly during the day corresponding to physical activity. There are good indications that in these subjects the excess hyaluronan comes from the joints. Under stringent sampling conditions of serum it should be possible to extract interesting information on the inflammatory joint process. Increased hyaluronan levels are also seen in other inflammatory diseases and it is of special interest that high hyaluronan levels in patients with septic conditions is a sign of poor prognosis. Certain tumours, notably Wilms' tumour and mesothelioma, produce factors which activate synthesis of hyaluronan and increase its serum level. Rare hereditary diseases with disturbances of hyaluronan metabolism and elevated blood levels have also been discovered, e.g. Werner's syndrome and cutaneous hyaluronanosis. Information accumulated during the last decade regarding the metabolism of hyaluronan has made this polysaccharide an interesting clinical marker for a number of pathological conditions.

The role of hyaluronan in tumour neovascularization (review)

Tumour growth and metastasis are totally dependant upon neovascularization. The target cell for tumour neovascularization is the blood-vessel endothelial cell, and specific angiogenic molecules produced or induced by the tumour are believed to initiate the process. In this report, we review one of these angiogenic molecules, the glycosaminoglycan hyaluronan (HA), which appears to have differing roles in neovascularization depending on its molecular mass. High-molecular-mass HA is anti-angiogenic whereas oligosaccharides of HA, of specific size, actively stimulate endothelial-cell proliferation and migration, 2 of the key events associated with neovascularization, and induce angiogenesis in vivo. We provide details of the action of HA oligosaccharides on endothelial cells, from binding to cell-surface receptors, through activation of signal transduction pathways and gene expression to protein synthesis, cell proliferation and cell migration. We also suggest a model to account for HA of differing molecular mass being present, at different locations, within a single tumour and how this HA aids both general tumour growth and tumour metastasis.

Urinary hyaluronic acid is a Wilms' tumor marker

Wilms' tumor is a renal neoplasm that is histologically similar to fetal kidney tissue. Both Wilms' tumor and the fetal kidney have high levels of the glycosaminoglycan hyaluronic acid (HA) in the extracellular matrix. Preliminary studies suggest that urinary HA levels are elevated in Wilms' tumor patients. To test the utility of urinary HA as a Wilms' tumor marker, the authors compared HA levels in urine specimens from 105 Wilms' tumor patients with those of 17 age-matched controls. Preoperative urine samples (n = 92), early postoperative samples, obtained from 1 to 3 weeks after surgery (n = 63), and late postoperative samples, obtained from 1 to 6 months after surgery (n = 58) were collected from patients at 30 institutions between 1989 and 1993. The HA levels were determined in triplicate by a competitive enzyme-linked immunosorbent binding assay. Seventy-four percent of the preoperative urine specimens contained elevated HA levels compared with the controls. The preoperative HA levels were significantly higher than the early postoperative (P < .01), late postoperative (P < .01), and control levels (P < .01). There was significant correlation between preoperative HA levels and clinical tumor staging. The mean preoperative HA level for patients with histological evidence of nephroblastomatosis was higher than that for patients without nephroblastomatosis. In the late postoperative period, patients with relapse or persistent disease had higher levels of urinary HA than did the disease-free patients (P < .05). In Wilms' tumor patients, urinary HA levels are elevated preoperatively and decline progressively after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Inverse relationship between hyaluronan and collagens in development and angiogenesis

The extracellular matrix plays a vital role in regulating normal tissue development and function--largely via the specific arrangement of macromolecules such as collagens, proteoglycans, glycosaminoglycans and glycoproteins. Previous reports have concentrated on associations between combinations of collagens/proteoglycans, collagens/glycoproteins and proteoglycans/glycosaminoglycans whilst little information is available on associations between collagens and free glycosaminoglycans. In this review, we discuss possible associations between collagens and the glycosaminoglycan hyaluronan; macromolecules which are known to exhibit changes in amount and composition during development and under pathological conditions. We demonstrate two types of collagen/hyaluronan association in vivo: the first, during the formation of extracellular matrix structures where neither collagens nor hyaluronan are degraded, resulting in the regulation of collagen fibrillogenesis, and the second, involving an inverse correlation between collagen synthesis and hyaluronan degradation and vice versa. We suggest that associations between collagens and hyaluronan play an important role in the initiation and maintenance of angiogenesis and put forward a model of cartilage vascularisation which relies on these associations.

Serum biological markers and paraneoplastic syndromes in Wilms tumor

Various tumors secrete tumor-specific substances capable of producing signs and symptoms in host organs not caused by direct tumor invasion or organ destruction. These symptoms are collectively referred to as "remote effects" or "paraneoplastic syndromes" of malignancy. Paraneoplastic syndromes are uncommon in childhood cancer. In Wilms tumor several distinct paraneoplastic syndromes have been reported: hypertension, erythrocytosis, hypercalcemia, Cushing syndrome, and acquired Von Willebrand disease. In addition some tumor-specific substances are known to be elevated in patients with a malignancy without causing specific symptoms. These so called "tumor markers" can be used to detect early recurrence in previously treated patients, or in the evaluation of patients undergoing adjuvant therapy. Five of particular interest are erythropoietin, neuron-specific enolase (NSE), hyaluronic acid (HA), hyaluronic acid-stimulating activity (HSA), and hyaluronidase.

Prognostic relevance of serum hyaluronan levels in patients with breast cancer

The serum hyaluronan (HA) level of 238 women with breast cancer was measured by means of a specific radiometric assay. The results show no significant increase in serum HA when compared to levels in 120 control sera. A number of prognostic factors were evaluated including stage of disease, lymph-node involvement, tumour size, histology and presence of oestrogen and progesterone receptors in the tumour. No correlation was found with serum HA concentration and we conclude that serum HA level is of no prognostic significance in breast cancer.