Hyaluronan: from extracellular glue to pericellular cue

The 'sweet' and 'bitter' involvement of glycosaminoglycans in lung diseases: pharmacotherapeutic relevance

The extracellular matrix (ECM) plays a significant role in the structure and function of the lung. The ECM is a three-dimensional fibre mesh, comprised of various interconnected and intercalated macromolecules, among which are the glycosaminoglycans (GAG). GAG are long, linear and highly charged, heterogeneous polysaccharides that are composed of a variable number of repeating disaccharide units (macromolecular sugars) and most of them, as their name implies, have a sweet taste. In the lung, GAG support the structure of the interstitium, the subepithelial tissue and the bronchial walls, and are secreted in the airway secretions. Besides maintaining lung tissue structure, GAG also play an important role in lung function as they regulate hydration and water homeostasis, modulate the inflammatory response and influence lung tissue repair and remodelling. However, depending on their size and/or degree of sulphation, and their immobilization or solubilization in the ECM, specific GAG in the lung either live up to their sweet taste/name, supporting normal lung physiology, or they are associated to 'bitter' effects, related to lung pathology. The present review discusses the biological role of GAG in the lung as well as the involvement of these molecules in various respiratory diseases. Given the great structural diversity of GAG, understanding the changes in GAG expression that occur in lung diseases may lead to novel targets for pharmacological intervention in order to prevent and/or to treat a range of lung diseases.

Abrogating drug resistance in malignant peripheral nerve sheath tumors by disrupting hyaluronan-CD44 interactions with small hyaluronan oligosaccharides

Malignant peripheral nerve sheath tumors (MPNST) develop in approximately 10% of neurofibromatosis type-1 patients and are a major contributing factor to neurofibromatosis-1 patient mortality and morbidity. MPNSTs are multidrug resistant, and thus long-term patient survival rates are poor after standard doxorubicin or multiagent chemotherapies. We show that the hyaluronan receptor CD44 forms complexes with multidrug transporters, BCRP (ABCG2) and P-glycoprotein (ABCB1), in the plasma membrane of human MPNST cells. Small hyaluronan oligosaccharides antagonize hyaluronan-CD44-mediated processes and inhibit hyaluronan production. Treatment of MPNST cells with the hyaluronan oligomers causes disassembly of CD44-transporter complexes and induces internalization of CD44, BCRP, and P-glycoprotein. Consequently, the oligomers suppress drug transporter activity and increase sensitivity to doxorubicin treatment in culture. In vivo, systemic administration of hyaluronan oligomers inhibits growth of MPNST xenografts. Moreover, the oligomers and doxorubicin act synergistically in vivo, in that combined suboptimal doses induce tumor regression to a greater extent than the additive effects of each agent alone. These findings indicate that constitutive hyaluronan-CD44 interactions contribute to drug transporter localization and function at the plasma membrane, and that attenuating hyaluronan-CD44 interactions sensitizes MPNSTs to doxorubicin in vitro and in vivo. These results also show the potential efficacy of hyaluronan oligomers, which are nontoxic and nonimmunogenic, as an adjuvant for chemotherapy in MPNST patients.

Aberrant splice variants of HAS1 (Hyaluronan Synthase 1) multimerize with and modulate normally spliced HAS1 protein: a potential mechanism promoting human cancer

Most human genes undergo alternative splicing, but aberrant splice forms are hallmarks of many cancers, usually resulting from mutations initiating abnormal exon skipping, intron retention, or the introduction of a new splice sites. We have identified a family of aberrant splice variants of HAS1 (the hyaluronan synthase 1 gene) in some B lineage cancers, characterized by exon skipping and/or partial intron retention events that occur either together or independently in different variants, apparently due to accumulation of inherited and acquired mutations. Cellular, biochemical, and oncogenic properties of full-length HAS1 (HAS1-FL) and HAS1 splice variants Va, Vb, and Vc (HAS1-Vs) are compared and characterized. When co-expressed, the properties of HAS1-Vs are dominant over those of HAS1-FL. HAS1-FL appears to be diffusely expressed in the cell, but HAS1-Vs are concentrated in the cytoplasm and/or Golgi apparatus. HAS1-Vs synthesize detectable de novo HA intracellularly. Each of the HAS1-Vs is able to relocalize HAS1-FL protein from diffuse cytoskeleton-anchored locations to deeper cytoplasmic spaces. This HAS1-Vs-mediated relocalization occurs through strong molecular interactions, which also serve to protect HAS1-FL from its otherwise high turnover kinetics. In co-transfected cells, HAS1-FL and HAS1-Vs interact with themselves and with each other to form heteromeric multiprotein assemblies. HAS1-Vc was found to be transforming in vitro and tumorigenic in vivo when introduced as a single oncogene to untransformed cells. The altered distribution and half-life of HAS1-FL, coupled with the characteristics of the HAS1-Vs suggest possible mechanisms whereby the aberrant splicing observed in human cancer may contribute to oncogenesis and disease progression.

Chondroitin sulfate increases hyaluronan production by human synoviocytes through differential regulation of hyaluronan synthases: Role of p38 and Akt

OBJECTIVE

To uncover the mechanism by which chondroitin sulfate (CS) enhances hyaluronan (HA) production by human osteoarthritic (OA) fibroblast-like synoviocytes (FLS).

METHODS

The production of HA was investigated by exposing human OA FLS to CS in the presence or absence of interleukin-1beta (IL-1beta). HA levels were determined by enzyme-linked immunosorbent assay, and levels of messenger RNA (mRNA) for HA synthase 1 (HAS-1), HAS-2, and HAS-3 were determined by real-time polymerase chain reaction analysis. The effect of CS and IL-1beta on signaling pathways was assessed by Western blotting. Specific inhibitors were used to determine their effects on both HA production and HAS expression. The molecular size of HA was analyzed by high-pressure liquid chromatography.

RESULTS

CS increased HA production by FLS through up-regulation of the expression of HAS1 and HAS2. This was associated with activation of ERK-1/2, p38, and Akt, although to a lesser extent. Both p38 and Akt were involved in CS-induced HA accumulation. IL-1beta increased HA production and levels of mRNA for HAS1, HAS2, and HAS3. CS enhanced the IL-1beta-induced level of HAS2 mRNA and reduced the level of HAS3 mRNA. IL-1beta-induced activation of p38 and JNK was slightly decreased by CS, whereas that of ERK-1/2 and Akt was enhanced. More high molecular weight HA was found in CS plus IL-1beta-treated FLS than in FLS treated with IL-1beta alone.

CONCLUSION

CS stimulates the synthesis of high molecular weight HA in OA FLS through up-regulation of HAS1 and HAS2. It reduces the IL-1beta-enhanced transcription of HAS3 and increases the production of HA of large molecular sizes. These effects may be beneficial for maintaining viscosity and antiinflammatory properties in the joint.

Biomimetic regeneration of elastin matrices using hyaluronan and copper ion cues

Current efforts to tissue engineer elastin-rich vascular constructs and grafts are limited because of the poor elastogenesis of adult vascular smooth muscle cells (SMCs) and the unavailability of appropriate cues to upregulate and enhance cross-linking of elastin precursors (tropoelastin) into organized, mature elastin fibers. We earlier showed that hyaluronan (HA) fragments greatly enhance tropo- and matrix-elastin synthesis by SMCs, although the yield of matrix elastin is low. To improve matrix yields, here we investigate the benefits of adding copper (Cu(2+)) ions (0.01 M and 0.1 M), concurrent with HA (756-2000 kDa), to enhance lysyl oxidase (LOX)-mediated elastin cross-linking machinery. Although absolute elastin amounts in test groups were not different from those in controls, on a per-cell basis, 0.1 M of Cu(2+) ions slowed cell proliferation (5.6 +/- 2.3-fold increase over 21 days vs 22.9 +/- 4.2-fold for non-additive controls), stimulated synthesis of collagen (4.1 +/- 0.4-fold), tropoelastin (4.1 +/- 0.05-fold) and cross-linked matrix elastin (4.2 +/- 0.7-fold). LOX protein synthesis increased 2.5 times in the presence of 0.1 M of Cu(2+) ions, and these trends were maintained even in the presence of HA fragments, although LOX functional activity remained unchanged in all cases. The abundance of elastin and LOX in cell layers cultured with 0.1 M of Cu(2+) ions and HA fragments was qualitatively confirmed using immunoflourescence. Scanning electron microscopy images showed that SMC cultures supplemented with 0.1 M of Cu(2+) ions and HA oligomers and large fragments exhibited better deposition of mature elastic fibers ( approximately 1 mum diameter). However, 0.01 M of Cu(2+) ions did not have any beneficial effect on elastin regeneration. In conclusion, the results suggest that supplying 0.1 M of Cu(2+) ions to SMCs to concurrently (a) enhance per-cell yield of elastin matrix while allowing cells to remain viable and synthetic and not density-arrested in long-term culture because of their moderating effects on otherwise rapid cell proliferation and (b) provide additional benefits of enhanced elastin fiber formation and cross-linking within these tissue-engineered constructs.

Hyaluronan substratum induces multidrug resistance in human mesenchymal stem cells via CD44 signaling

Little information is available concerning multidrug resistance (MDR) in mesenchymal stem cells, although several studies have reported that MDR is associated with hyaluronan in neoplastic cells. We have evaluated whether a hyaluronan-coated surface modulates MDR in placenta-derived human mesenchymal stem cells (PDMSCs). We have found that PDMSCs cultured on a tissue-culture polystyrene surface coated with 30 microg/cm(2) hyaluronan are more resistant than control PDMSCs to doxorubicin. Inhibiting PI3K/Akt signaling has shown that the PI3K/Akt pathway modulates both P-glycoprotein activity and doxorubicin resistance. In addition, 10 microM verapamil dramatically suppresses the doxorubicin resistance induced by the hyaluronan-coated surface, indicating that P-glycoprotein activity is necessary for MDR. We have further found that PDMSCs treated with CD44 small interfering RNA (siRNA) and grown on a polystyrene surface coated with 30 microg/cm(2) hyaluronan have fewer P-glycoprotein(+) cells and lower CD44 expression levels (less than 60% in both cases) than PDMSCs not treated with CD44 siRNA and grown on the hyaluronan-coated surface. Moreover, treatment with CD44 siRNA suppresses the hyaluronan-substratum-induced doxorubicin resistance. We conclude that a hyaluronan substratum induces MDR in PDMSCs through CD44 signaling.

Rheology and confocal reflectance microscopy as probes of mechanical properties and structure during collagen and collagen/hyaluronan self-assembly

In this work, the gelation of three-dimensional collagen and collagen/hyaluronan (HA) composites is studied by time sweep rheology and time lapse confocal reflectance microscopy (CRM). To investigate the complementary nature of these techniques, first collagen gel formation is investigated at concentrations of 0.5, 1.0, and 1.5 mg/mL at 37 degrees C and 32 degrees C. The following parameters are used to describe the self-assembly process in all gels: the crossover time (t(c)), the slope of the growth phase (k(g)), and the arrest time (t(a)). The first two measures are determined by rheology, and the third by CRM. A frequency-independent rheological measure of gelation, t(g), is also measured at 37 degrees C. However, this quantity cannot be straightforwardly determined for gels formed at 32 degrees C, indicating that percolation theory does not fully capture the dynamics of collagen network formation. The effects of collagen concentration and gelation temperature on k(g), t(c), and t(a) as well as on the mechanical properties and structure of these gels both during gelation and at equilibrium are elucidated. Composite collagen/HA gels are also prepared, and their properties are monitored at equilibrium and during gelation at 37 degrees C and 32 degrees C. We show that addition of HA subtly alters mechanical properties and structure of these systems both during the gelation process and at equilibrium. This occurs in a temperature-dependent manner, with the ratio of HA deposited on collagen fibers versus that distributed homogeneously between fibers increasing with decreasing gelation temperature. In addition to providing information on collagen and collagen/HA structure and mechanical properties during gelation, this work shows new ways in which rheology and microscopy can be used complementarily to reveal details of gelation processes.

Cyclooxygenase inhibitors repress vascular hyaluronan-synthesis in murine atherosclerosis and neointimal thickening

Hyaluronan (HA) is a key molecule of the extracellular matrix that is thought to be critically involved in both atherosclerosis and restenosis. Recently, it has been demonstrated that the cyclooxygenase (COX) products, prostacyclin and prostaglandin E(2), induce HA synthesis in vitro by transcriptional up-regulation of HA-synthase 2 (HAS2) and HAS1. The relative roles in atherosclerotic and restenotic artery disease of tissue specifically expressed COX-1 and COX-2 are still under debate. Thus, the present study aimed to investigate the effect of COX isoform inhibition on HA-accumulation and regulation of HAS isoform expression in two models of pathologic artery remodelling in vivo. Firstly, ApoE-deficient mice were treated with a prototypic isoform non-selective inhibitor, indomethacin or with a prototypic COX-2 selective inhibitor, rofecoxib, for 8 weeks. Aortic HAS mRNA expression and HA-accumulation in atherosclerotic aortic root lesions were analyzed. Secondly, neointimal hyperplasia was induced by carotid artery ligation in ApoE-deficient mice on a high fat diet and the effects of the COX inhibitors were determined after 4 weeks of treatment. Intimal HA-accumulation was markedly reduced in both models by indomethacin and rofecoxib. This coincided with a strong inhibition of HAS1 mRNA expression in both models and with decreased HAS2 mRNA in the aorta of ApoE-deficient mice. HAS3 was not affected. The repression of HA-accumulation by both COX-2 selective and non-selective COX inhibition implicates COX-2 in the regulation of HA synthesis via stimulation of HAS1 and HAS2 expression in vivo. Modulation of vascular HA-accumulation might play a role in chronic effects of COX inhibitors on the progression of atherosclerosis.

Cellular/intramuscular myxoma and grade I myxofibrosarcoma are characterized by distinct genetic alterations and specific composition of their extracellular matrix

Cellular myxoma and grade I myxofibrosarcoma are mesenchymal tumours that are characterized by their abundant myxoid extracellular matrix (ECM). Despite their histological overlap, they differ clinically. Diagnosis is therefore difficult though important. We investigated their (cyto) genetics and ECM. GNAS1-activating mutations have been described in intramuscular myxoma, and lead to downstream activation of cFos. KRAS and TP53 mutations are commonly involved in sarcomagenesis whereby KRAS subsequently activates c-Fos. A well-documented series of intramuscular myxoma (three typical cases and seven cases of the more challenging cellular variant) and grade I myxofibrosarcoma (n= 10) cases were karyotyped, analyzed for GNAS1, KRAS and TP53 mutations and downstream activation of c-Fos mRNA and protein expression. ECM was studied by liquid chromatography mass spectrometry and expression of proteins identified was validated by immunohistochemistry and qPCR. Grade I myxofibrosarcoma showed variable, non-specific cyto-genetic aberrations in 83,5% of cases (n= 6) whereas karyotypes of intramuscular myxoma were all normal (n= 7). GNAS1-activating mutations were exclusively found in 50% of intramuscular myxoma. Both tumour types showed over-expression of c-Fos mRNA and protein. No mutations in KRAS codon 12/13 or in TP53 were detected. Liquid chromatography mass spectrometry revealed structural proteins (collagen types I, VI, XII, XIV and decorin) in grade I myxofibrosarcoma lacking in intramuscular myxoma. This was confirmed by immunohistochemistry and qPCR. Intramuscular/cellular myxoma and grade I myxofibrosarcoma show different molecular genetic aberrations and different composition of their ECM that probably contribute to their diverse clinical behaviour. GNAS1 mutation analysis can be helpful to distinguish intramuscular myxoma from grade I myxofibrosarcoma in selected cases.

Delivery of CD44 shRNA/nanoparticles within cancer cells: perturbation of hyaluronan/CD44v6 interactions and reduction in adenoma growth in Apc Min/+ MICE

Our studies have shown that constitutive interactions between hyaluronan and CD44 on tumor cells induces various anti-apoptotic cell survival pathways through the formation of a multimeric signaling complex that contains activated receptor tyrosine kinases. Inhibition of the hyaluronan-CD44 interactions on tumor cells by hyaluronan-CD44 interaction antagonists suppresses these activities by disassembling the complex. Although the anti-tumor activity of hyaluronan-oligosaccharides, a hyaluronan-CD44 interaction antagonist, is effective in sensitizing tumor cells to chemotherapeutic agents and reducing tumor growth in xenografts, hyaluronan-oligosaccharide alone was not effective in reducing tumor progression in Apc Min/+ mice. We now show in vitro and in vivo that targeted inhibition of the expression of CD44v6 depletes the ability of the colon tumor cells to signal through hyaluronan-CD44v6 interactions. First, we cloned oligonucleotides coding CD44v6 shRNA into a conditionally silenced pSico vector. Second, using pSico-CD44v6 shRNA and a colon-specific Fabpl promoter-driven Cre recombinase expression vector packaged into transferrin-coated nanoparticles, we successfully delivered the CD44v6 shRNA within pre-neoplastic and neoplastic colon malignant cells. Third, using the Apc Min/+ mice model, we demonstrated that inhibition of the CD44v6 expression reduces the signaling through a hyaluronan/CD44v6-pErbB2-Cox-2 interaction pathway and reduced adenoma number and growth. Together, these data provide insight into the novel therapeutic strategies of short hairpin RNA/nanoparticle technology and its potential for silencing genes associated with colon tumor cells.

Spontaneous metastasis of prostate cancer is promoted by excess hyaluronan synthesis and processing

Accumulation of extracellular hyaluronan (HA) and its processing enzyme, the hyaluronidase Hyal1, predicts invasive, metastatic progression of human prostate cancer. To dissect the roles of hyaluronan synthases (HAS) and Hyal1 in tumorigenesis and metastasis, we selected nonmetastatic 22Rv1 prostate tumor cells that overexpress HAS2, HAS3, or Hyal1 individually, and compared these cells with co-transfectants expressing Hyal1 + HAS2 or Hyal1 + HAS3. Cells expressing only HAS were less tumorigenic than vector control transfectants on orthotopic injection into mice. In contrast, cells co-expressing Hyal1 + HAS2 or Hyal1 + HAS3 showed greater than sixfold and twofold increases in tumorigenesis, respectively. Fluorescence and histological quantification revealed spontaneous lymph node metastasis in all Hyal1 transfectant-implanted mice, and node burden increased an additional twofold when Hyal1 and HAS were co-expressed. Cells only expressing HAS were not metastatic. Thus, excess HA synthesis and processing in concert accelerate the acquisition of a metastatic phenotype by prostate tumor cells. Intratumoral vascularity did not correlate with either tumor size or metastatic potential. Analysis of cell cycle progression revealed shortened doubling times of Hyal1-expressing cells. Both adhesion and motility on extracellular matrix were diminished in HA-overproducing cells; however, motility was increased twofold by Hyal1 expression and fourfold to sixfold by Hyal1/HAS co-expression, in close agreement with observed metastatic potential. This is the first comprehensive examination of these enzymes in a relevant prostate cancer microenvironment.

CD44 variant isoforms promote metastasis formation by a tumor cell-matrix cross-talk that supports adhesion and apoptosis resistance

CD44 designates a large family of proteins with a considerable structural and functional diversity, which are generated from one gene by alternative splicing. As such, the overexpression of CD44 variant isoform (CD44v) has been causally related to the metastatic spread of cancer cells. To study the underlying mechanism, stable knockdown clones with deletion of exon v7 containing CD44 isoforms (CD44v(kd)) of the highly metastatic rat adenocarcinoma line BSp73ASML (ASML(wt)) were established. ASML-CD44v(kd) clones hardly form lung metastases after intrafootpad application and the metastatic load in lymph nodes is significantly reduced. Rescuing, albeit at a reduced level, CD44v expression in ASML-CD44v(kd) cells (ASML-CD44v(rsc)) restores the metastatic potential. The following major differences in ASML(wt), ASML-CD44v(kd), and ASML-CD44v(rsc) clones were observed: (a) ASML(wt) cells produce and assemble a matrix in a CD44v-dependent manner, which supports integrin-mediated adhesion and favors survival. This feature is lost in the ASML-CD44v(kd) cells. (b) CD44v cross-linking initiates phosphatidylinositol 3-kinase/Akt activation in ASML(wt) cells. Accordingly, apoptosis resistance is strikingly reduced in ASML-CD44v(kd) cells. The capacity to generate an adhesive matrix but not apoptosis resistance is restored in ASML-CD44v(rsc) cells. These data argue for a 2-fold effect of CD44v on metastasis formation: CD44v-mediated matrix formation is crucial for the settlement and growth at a secondary site, whereas apoptosis resistance supports the efficacy of metastasis formation.

Synthesis and cellular uptake of fluorescently labeled multivalent hyaluronan disaccharide conjugates of oligonucleotide phosphorothioates

Clustered hyaluronan disaccharides were studied as mediators of cellular delivery of antisense oligonucleotides through receptor-mediated endocytosis. For this purpose, a synthetic route for preparation of an appropriately protected hyaluronic acid dimer bearing an aldehyde tether (1) was devised. Up to three non-nucleosidic phosphoramidite building blocks (2), each bearing two phthaloyl protected aminooxy groups, were then inserted into the 3'-terminus of the desired phosphorothioate oligodeoxyribonucleotide, and 6-FAM phosphoramidite was introduced into the 5'-terminus. After completion of the chain assembly, the aldehyde-tethered sugar ligands were attached to the deprotected aminooxy functions by on-support oximation. Three fluorescein-labeled phosphorothioate oligonucleotide glycoconjugates (28-30) containing two, four, or six hyaluronan disaccharides were prepared. The influence of the hyaluronan moieties on the cellular uptake of the thioated oligonucleotides was tested in a cell line expressing the hyaluronan receptor CD44. Specific uptake was not detected with this combination of multiple hyaluronan disaccharides.

The role of the extracellular matrix and specific growth factors in the regulation of inflammation and remodelling in asthma

Asthma is a disease characterised by persistent inflammation and structural changes in the airways, referred to as airway remodelling. The mechanisms underlying these processes may be interdependent or they may be separate processes that are driven by common factors. The levels of a variety of growth factors (including transforming growth factor beta, granulocyte macrophage colony stimulating factor, and vascular endothelial growth factor) are known to be changed in the asthmatic airway. These and other growth factors can contribute to the development and persistence of inflammation and remodelling. One of the prominent features of the structural changes of the airways is the increased deposition and alterations in the composition of the extracellular matrix proteins. These proteins include fibronectin, many different collagen types and hyaluronan. There is a dynamic relationship between the extracellular matrix proteins and the airway mesenchymal cells such that the changes in the extracellular matrix proteins can also contribute to the persistence of inflammation and the airway remodelling. This review aims to summarise the role growth factors and extracellular matrix proteins play in the regulation of inflammation and airway remodelling in the asthmatic airway.

Targeting stromal-cancer cell interactions with siRNAs

Tumors are composed of both malignant and normal cells, including fibroblasts, endothelial cells, mesenchymal stem cells, and inflammatory immune cells such as macrophages. These various stromal components interact with cancer cells to promote growth and metastasis. For example, macrophages, attracted by colony-stimulating factor-1 (CSF-1) produced by tumor cells, in turn produce various growth factors such as vascular endothelial growth factor, which supports the growth of tumor cells and their interaction with blood vessels leading to enhanced tumor cell spreading. The activation of autocrine and paracrine oncogenic signaling pathways by stroma-derived growth factors and cytokines has been implicated in promoting tumor cell proliferation and metastasis. Furthermore, matrix metalloproteinases (MMPs) derived from both tumor cells and the stromal compartment are regarded as major players assisting tumor cells during metastasis. Collectively, these recent findings indicate that targeting tumor-stroma interactions is a promising strategy in the search for novel treatment modalities in human cancer. This chapter summarizes our current understanding of the tumor microenvironment and highlights some potential targets for therapeutic intervention with small interfering RNAs.

Hyaluronan induces cell death in activated T cells through CD44

In the immune system, leukocyte activation induces CD44 to bind hyaluronan, a component of the extracellular matrix. Here we used gain and loss of hyaluronan-binding mutants of CD44 to examine the consequence of hyaluronan binding in T cells. Jurkat T cells transfected with CD44 mutated at S180, which prevented the addition of chondroitin sulfate, displayed constitutively high levels of hyaluronan binding. These cells were more susceptible to activation-induced cell death, whereas cells expressing a CD44 mutant unable to bind hyaluronan (R41A) were resistant to cell death. In TCR or PMA activated Jurkat T cells, hyaluronan induced rapid cell death. This depended on the level of hyaluronan binding by the cell, and the amount and size of hyaluronan. High molecular mass hyaluronan had the greatest effect and cell death occurred independently of Fas and caspase activation. In splenic T cells, high hyaluronan binding occurred in a subpopulation of cells undergoing activation-induced cell death. In addition, hyaluronan induced cell death in approximately 10% of reactivated splenic T cells when Fas-dependent apoptosis was prevented by Ab blocking or in Fas negative MRL/lpr T cells. This demonstrates that hyaluronan can induce cell death in activated, high hyaluronan binding T cells via a Fas-independent mechanism.

Hyaluronan-binding receptors: possible involvement in osteoarthritis

Our objectives were to compare the expression of the hyaluronan receptors CD44 and RHAMM in knee synovial tissue of patients with and without advanced osteoarthritis (OA). Both receptors were detected immunohistochemically; the staining appeared more intense in the tissues from the patients with advanced OA. Expression of CD44 and RHAMM were each significantly increased (p < 0.05) in synovial tissue from patients with OA, as determined by means of Western-blot analysis. The findings suggested that changes in levels of the HA-binding proteins might be implicated in the development or progression of OA.

In vivo water state measurements in breast cancer using broadband diffuse optical spectroscopy

Structural changes in water molecules are related to physiological, anatomical and pathological properties of tissues. Near infrared (NIR) optical absorption methods are sensitive to water; however, detailed characterization of water in thick tissues is difficult to achieve because subtle spectral shifts can be obscured by multiple light scattering. In the NIR, a water absorption peak is observed around 975 nm. The precise NIR peak's shape and position are highly sensitive to water molecular disposition. We introduce a bound water index (BWI) that quantifies shifts observed in tissue water absorption spectra measured by broadband diffuse optical spectroscopy (DOS). DOS quantitatively measures light absorption and scattering spectra and therefore reveals bound water spectral shifts. BWI as a water state index was validated by comparing broadband DOS to magnetic resonance spectroscopy, diffusion-weighted MRI and conductivity in bound water tissue phantoms. Non-invasive DOS measurements of malignant and normal breast tissues performed in 18 subjects showed a significantly higher fraction of free water in malignant tissues (p < 0.0001) compared to normal tissues. BWI of breast cancer tissues inversely correlated with Nottingham-Bloom-Richardson histopathology scores. These results highlight broadband DOS sensitivity to molecular disposition of water and demonstrate the potential of BWI as a non-invasive in vivo index that correlates with tissue pathology.

Mammalian hyaluronidase induces ovarian granulosa cell apoptosis and is involved in follicular atresia

During ovarian folliculogenesis, the vast majority of follicles will undergo atresia by apoptosis, allowing a few dominant follicles to mature. Mammalian hyaluronidases comprise a family of six to seven enzymes sharing the same catalytic domain responsible for hyaluronan hydrolysis. Interestingly, some of these enzymes have been shown to induce apoptosis. In the ovary, expression of three hyaluronidases (Hyal-1, Hyal-2, and Hyal-3) has been documented. However, their precise cellular localization and role in ovarian regulation have not yet been defined. We herein investigated the possible involvement of these enzymes in ovarian atresia. First, we established a mouse model for ovarian atresia (gonadotropin withdrawal by anti-equine chorionic gonadotropin treatment) and showed that the mRNA levels of Hyal-1, Hyal-2, and Hyal-3 were significantly increased in apoptotic granulosa cells as well as in atretic follicles. Second, using ovaries of normally cycling mice, we demonstrated the correlation of Hyal-1 mRNA and protein expression with cleavage of caspase-3. In addition, we showed that expression of all three hyaluronidases induced apoptosis in transfected granulosa cells. Significantly, the induction of apoptosis by hyaluronidases was independent of catalytic activity, because enzymatically inactive Hyal-1 mutant (D157A/E159A) was as efficient as the wild-type enzyme in apoptosis induction. The activation of the extrinsic apoptotic signaling pathway was involved in this induction, because increased levels of cleaved caspase-8, caspase-3, and poly-ADP-ribose polymerase (PARP) were observed upon hyaluronidase ectopic expression. Our present findings provide a better understanding of the role of hyaluronidases in ovarian functions, showing for the first time their involvement in follicular atresia.

Hyaluronan substratum holds mesenchymal stem cells in slow-cycling mode by prolonging G1 phase

We examined, in vitro, whether hyaluronan induces slow cycling in placenta-derived mesenchymal stem cells (PDMSCs) by comparing cell growth on a hyaluronan-coated surface with cell growth on a tissue-culture polystyrene surface. The hyaluronan-coated surface significantly downregulated the proliferation of PDMSCs, more of which were maintained in the G(0)/G(1) phases than were cells on the tissue-culture polystyrene surface. Both PKH-26 labeling and BrdU incorporation assays showed that most PDMSCs grown on a hyaluronan-coated surface duplicated during cultivation indicating that the hyaluronan-coated surface did not inhibit PDMSCs from entering the cell cycle. Mitotic synchronization showed that the G(1)-phase transit was prolonged in PDMSCs growing on a hyaluronan-coated surface. Increases in p27(Kip1) and p130 were the crucial factors that allowed hyaluronan to lengthen the G(1) phase. Thus, hyaluronan might be a promising candidate for maintaining stem cells in slow-cycling mode by prolonging their G(1)-phase transit.

Targeting hyaluronan interactions in spinal cord astrocytomas and diffuse pontine gliomas

Although significant advances have been made in treating malignant pediatric central nervous system tumors such as medulloblastoma, no effective therapy exists for diffuse pontine glioma or intramedullary spinal astrocytoma. Biology of these 2 tumors is poorly understood, in part because diffuse pontine gliomas are not treated surgically, and tumor specimens from intramedullary spinal astrocytomas are rare and minuscule. At the 2007 Neurobiology of Disease in Children Symposium, we presented evidence that malignant glioma behaviors, including antiapoptosis, invasiveness, and treatment resistance, are enhanced by hyaluronan, an extracellular glycosaminoglycan. We review the clinical course of pediatric intramedullary spinal astrocytoma and diffuse pontine glioma, and show expression of membrane proteins that interact with hyaluronan: CD44, extracellular matrix metalloproteinase inducer, and breast cancer resistance protein (BCRP/ABCG2). Furthermore, we describe novel animal models of these tumors for preclinical studies. These findings suggest that hyaluronan antagonism has potential therapeutic value in malignant central nervous system tumors.

Hyaluronan regulates ceruloplasmin production by gliomas and their treatment-resistant multipotent progenitors

Ceruloplasmin (glycosylphosphatidylinositol-linked ferroxidase associated with normal astrocytes) can also be secreted by glioma cells, where its function is unknown. Ceruloplasmin is not only present in glioma cells and in human glioma specimens but also is enriched in highly malignant glioma stem-like cells. Hyaluronan is a large extracellular glycosaminoglycan that enhances malignant glioma behaviors by interacting with CD44 receptors and by downstream activation of signaling proteins and transporters associated with malignancy. We examined the relationship between hyaluronan and ceruloplasmin expression in glioma stem-like cells. Antagonism of hyaluronan interactions with short-fragment hyaluronan oligomers decreased ceruloplasmin expression in parental and stem-like glioma cells in vivo and in cell culture, implying that hyaluronan regulates ceruloplasmin expression. Further gain and loss-of-function studies are needed to fully define the relationship between hyaluronan and ceruloplasmin, and ceruloplasmin's effect on malignant behaviors.

Regulation of vascular permeability by sphingosine 1-phosphate

A significant and sustained increase in vascular permeability is a hallmark of acute inflammatory diseases such as acute lung injury (ALI) and sepsis and is an essential component of tumor metastasis, angiogenesis, and atherosclerosis. Sphingosine 1-phosphate (S1P), an endogenous bioactive lipid produced in many cell types, regulates endothelial barrier function by activation of its G-protein coupled receptor S1P(1). S1P enhances vascular barrier function through a series of profound events initiated by S1P(1) ligation with subsequent downstream activation of the Rho family of small GTPases, cytoskeletal reorganization, adherens junction and tight junction assembly, and focal adhesion formation. Furthermore, recent studies have identified transactivation of S1P(1) signaling by other barrier-enhancing agents as a common mechanism for promoting endothelial barrier function. This review summarizes the state of our current knowledge about the mechanisms through which the S1P/S1P(1) axis reduces vascular permeability, which remains an area of active investigation that will hopefully produce novel therapeutic agents in the near future.

A simple assay for hyaluronidase activity using fluorescence polarization

Hyaluronan is a large glycosaminoglycan and is a major constituent of the extracellular matrix, interacting with cell surface receptors such as CD44. We previously reported that fragmented hyaluronan, with the size frequently detected in cancer patients, induces CD44 cleavage and concomitantly enhances tumor cell migration. Although hyaluronan degradation to smaller fragments has been revealed to be a key reaction in regulating cancer progression, simple methods for continuously detecting hyaluronidase activity have not been established. Here, we show that fluorescently-labeled hyaluronan serves as a substrate for continuous assay of hyaluronidase activity. A very simple assay was established to measure degradation of hyaluronan based on fluorescence polarization. The developed assay method would provide a way for continuous measurement of cellular hyaluronidase activity and also for measurement of binding of hyaluronan to its receptors, and thus should be useful for investigation of the function of hyaluronan in cancer progression.

Benefits of concurrent delivery of hyaluronan and IGF-1 cues to regeneration of crosslinked elastin matrices by adult rat vascular cells

Elastin, a major component of vascular matrices, critically determines vascular mechanics and maintains the quiescence of smooth muscle cells (SMCs). Attempts to regenerate elastin in elastin-compromised blood vessels using tissue-engineering approaches is limited by the unavailability of elastogenic cues to upregulate poor elastin output and matrix assembly by adult vascular cells. We previously showed that hyaluronan (HA) elastogenically stimulates aortic SMCs, although these effects are highly specific to HA fragment size. The elastogenic response of SMCs can also be modulated with growth factors such as insulin-like growth factor (IGF-1). Here, we evaluate the benefits of concurrent delivery of HA fragments (0.76-2000 kDa) and IGF-1 (500 ng/ml) to elastin synthesis, organization and crosslinking. The study outcomes show that, relative to supplement-free cultures, IGF-1 and long-chain HA/large HA fragments, but not HA oligomers, together induce multifold increases in the synthesis of elastin precursors, structural elastin matrix yields and crosslink densities within cell layers, and encourage elastic fibre formation. These outcomes are not all obtained when either of the cues is provided separately. IGF-1 and large HA fragments (>20 kDa) also together inhibit cell proliferation, a concern in elastin-compromised vessels, where SMC hyperproliferation is common. The results will benefit efforts to provide exogenous or scaffold-based elastogenic cues (IGF-1 + HMW HA/large HA fragments) to enable robust and faithful regeneration of elastin matrix structures in vivo or in vitro. The present outcomes may be used to restore elastin matrix homeostasis in de-elasticized vessels and tissue-engineered constructs that may be grafted as a substitute.

Cutaneous mucinosis in shar-pei dogs is due to hyaluronic acid deposition and is associated with high levels of hyaluronic acid in serum

Cutaneous mucinosis affects primarily shar-pei dogs. Hyaluronic acid (HA) is considered to be the main component of mucin and CD44 is the major cell surface receptor of HA, necessary for its uptake and catabolism. The aims of this study were to identify the composition of the mucin in cutaneous mucinosis of shar-pei dogs, investigate the correlation between the deposition of HA and the expression of CD44, and determine whether shar-pei dogs with cutaneous mucinosis presented with elevated levels of serum HA. In skin biopsies, the mucinous material was stained intensely with Alcian blue and bound strongly by the hyaluronan-binding protein. No correlation was found between the degree of HA deposition in the dermis and the expression of CD44 in the skin of shar-pei dogs affected or unaffected by cutaneous mucinosis. A clear positive correlation was found between the existence of clinical mucinosis and the serum HA concentration. In control dogs, serum HA ranged from 155.53 to 301.62 microg L(-1) in shar-pei dogs; without mucinosis it ranged from 106.72 to 1251.76 microg L(-1) and in shar-pei dogs with severe mucinosis it ranged between 843.51 to 2330.03 microg L(-1). Altogether, the results reported here suggest that mucinosis of shar-pei dogs is probably the consequence of a genetic defect in the metabolism of HA.

Collagens, stromal cell-derived factor-1alpha and basic fibroblast growth factor increase cancer cell invasiveness in a hyaluronan hydrogel

OBJECTIVE

Beyond to control of cell migration, differentiation and proliferation, the extracellular matrix (ECM) also contributes to invasiveness of human cancers. As the roles of hyaluronan (HA) and collagens in this process are still controversial, we have investigated their involvement in cancer pathogenesis.

MATERIALS AND METHODS

With this aim in view, we developed a three-dimensional matrix, as reticulate HA hydrogel alone or coated with different collagens, in which cells could invade and grow.

RESULTS

We show that cancer cells, which were non-invasive in a single HA hydrogel, acquired this capacity in the concomitant presence of type I or III collagens. Both types of ECM compound, HA and collagens, possess the capacity to stimulate production of metalloprotease-2, recognized otherwise as a factor for poor cancer prognosis. HA-provoked cellular invasiveness resulted from CD44-mediated increase in cytosolic [Ca2+] and its subsequent hydrolysis due to ADAM (a disintegrin and metalloprotease) proteolytic activity. Interestingly, this mechanism seemed to be absent in non-invasive cancer cell lines.

CONCLUSION

Furthermore, using basic fibroblast growth factor and stromal cell-derived factor-1alpha, we also show that this three-dimensional reticulate matrix may be considered as a valuable model to study chemokinetic and chemotactic potentials of factors present in tumour stroma.

Impact of the hyaluronan-rich tumor microenvironment on cancer initiation and progression

Hyaluronan acts as a microenvironmental stimulus that can influence the malignant phenotype of cancer cells. During cancer progression, hyaluronan assembles an extracellular matrix that is favorable for both the motility and proliferation of cancer cells and the recruitment of inflammatory and bone marrow-derived progenitor cells. The varied roles of this polysaccharide are regulated via multiple mechanisms involving biosynthesis, degradation, binding with other extracellular molecules, and activation of signaling pathways. Recent animal studies have provided evidence that aberrant biosynthesis of hyaluronan accelerates tumor growth through a diverse repertoire of host-tumor interactions, such as stromal cell recruitment, angiogenesis, lymphangiogenesis, and inflammation. Hyaluronan in the tumor microenvironment thus significantly impacts cancer initiation and progression via stroma-cancer cell interactions.

Epigenetic regulation of HYAL-1 hyaluronidase expression. identification of HYAL-1 promoter

HYAL-1 (hyaluronoglucosaminidase-1) belongs to the hyaluronidase family of enzymes that degrade hyaluronic acid. HYAL-1 is a marker for cancer diagnosis and a molecular determinant of tumor growth, invasion, and angiogenesis. The regulation of HYAL-1 expression is unknown. Real time reverse transcription-PCR using 11 bladder and prostate cancer cells and 69 bladder tissues showed that HYAL-1 mRNA levels are elevated 10-30-fold in cells/tissues that express high hyaluronidase activity. Although multiple transcription start sites (TSS) for HYAL-1 mRNA were detected in various tissues, the major TSS in many tissues, including bladder and prostate, was at nucleotide 27274 in the cosmid clone LUCA13 (AC002455). By analyzing the 1532 base sequence 5' to this TSS, using cloning and luciferase reporter assays, we identified a TACAAA sequence at position -31 and the minimal promoter region between nucleotides -93 and -38. Mutational analysis identified that nucleotides -73 to -50 (which include overlapping binding consensus sites for SP1, Egr-1, and AP-2), bases C(-71) and C(-59), and an NFkappaB-binding site (at position -15) are necessary for promoter activity. The chromatin immunoprecipitation assay identified that Egr-1, AP-2, and NFkappaB bind to the promoter in HYAL-1-expressing cells, whereas SP1 binds to the promoter in non-HYAL-1-expressing cells. 5-Aza-2'-deoxycytidine treatment, bisulfite DNA sequencing, and methylation-specific PCR revealed that HYAL-1 expression is regulated by methylation at C(-71) and C(-59); both Cs are part of the SP1/Egr-1-binding sites. Thus, HYAL-1 expression is epigenetically regulated by the binding of different transcription factors to the methylated and unmethylated HYAL-1 promoter.

Epstein-Barr virus latent membrane protein 2A upregulates UDP-glucose dehydrogenase gene expression via ERK and PI3K/Akt pathway

The Epstein-Barr virus latent membrane protein 2A (LMP2A) is frequently detected in nasopharyngeal carcinoma (NPC), a tumour of high metastatic capacity. A recent microarray assay notes that expression of the UDP-glucose dehydrogenase (UGDH) gene, participating in glycosaminoglycan synthesis, shows high correlation with LMP2A levels in NPC biopsies. This study extends the finding and demonstrates that the UGDH transcript and protein quantities, the enzyme activity, and glycosaminoglycan contents increase in LMP2A overexpressed human embryonic kidney 293 (HEK293) cells. The luciferase reporter gene assay demarcates that a region from 630 to 486 bp upstream of the transcription start is critical for LMP2A-mediated gene expression. Moreover, a specificity protein 1 (Sp1) binding site mutation in this region reduces the LMP2A-responsive expression of the UGDH gene. Consistent with these findings, cell motility enhancement by LMP2A diminishes by treating the cells with Sp1-specific inhibitor and small interference RNA (siRNA). Using a signalling pathway-specific inhibitor, it is revealed that phosphatidylinositol 3-kinase (PI3K)/Akt and extracellular signal-regulated kinase (ERK), not c-Jun N-terminal kinase (JNK) and p38, participate in LMP2A-induced UGDH expression. This study provides a model for molecular mechanism participating in LMP2A-mediated UGDH gene activation.

Extracellular matrix of the central nervous system: from neglect to challenge

The basic concept, that specialized extracellular matrices rich in hyaluronan, chondroitin sulfate proteoglycans (aggrecan, versican, neurocan, brevican, phosphacan), link proteins and tenascins (Tn-R, Tn-C) can regulate cellular migration and axonal growth and thus, actively participate in the development and maturation of the nervous system, has in recent years gained rapidly expanding experimental support. The swift assembly and remodeling of these matrices have been associated with axonal guidance functions in the periphery and with the structural stabilization of myelinated fiber tracts and synaptic contacts in the maturating central nervous system. Particular interest has been focused on the putative role of chondroitin sulfate proteoglycans in suppressing central nervous system regeneration after lesions. The axon growth inhibitory properties of several of these chondroitin sulfate proteoglycans in vitro, and the partial recovery of structural plasticity in lesioned animals treated with chondroitin sulfate degrading enzymes in vivo have significantly contributed to the increased awareness of this long time neglected structure.

Cell-surface and mitotic-spindle RHAMM: moonlighting or dual oncogenic functions?

Tumor cells use a wide variety of post-translational mechanisms to modify the functional repertoire of their transcriptome. One emerging but still understudied mechanism involves the export of cytoplasmic proteins that then partner with cell-surface receptors and modify both the surface-display kinetics and signaling properties of these receptors. Recent investigations demonstrate moonlighting roles for the proteins epimorphin, FGF1, FGF2, PLK1 and Ku80, to name a few, during oncogenesis and inflammation. Here, we review the molecular mechanisms of unconventional cytoplasmic-protein export by focusing on the mitotic-spindle/hyaluronan-binding protein RHAMM, which is hyper-expressed in many human tumors. Intracellular RHAMM associates with BRCA1 and BARD1; this association attenuates the mitotic-spindle-promoting activity of RHAMM that might contribute to tumor progression by promoting genomic instability. Extracellular RHAMM-CD44 partnering sustains CD44 surface display and enhances CD44-mediated signaling through ERK1 and ERK2 (ERK1/2); it might also contribute to tumor progression by enhancing and/or activating the latent tumor-promoting properties of CD44. The unconventional export of proteins such as RHAMM is a novel process that modifies the roles of tumor suppressors and promoters, such as BRCA1 and CD44, and might provide new targets for therapeutic intervention.

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.

Extracellular matrix mediates a molecular balance between vascular morphogenesis and regression

PURPOSE OF REVIEW

We discuss very recent studies that address the critical role of extracellular matrix in controlling the balance between vascular morphogenesis and regression. Much of this work suggests that a balance mechanism exists for controlling the extent of tissue vascularization involving downstream signaling events regulating endothelial cell behaviors in relation to their interactions with extracellular matrix molecules.

RECENT FINDINGS

Endothelial gene expression changes and signaling lead to events that not only stimulate vascular morphogenesis but also suppress mechanisms mediated through pro-regression factors such as Rho kinase. At the same time, vascular networks are susceptible to regression mediated by factors such as matrix metalloproteinase-1, matrix metalloproteinase-10, thrombospondin-1, extracellular matrix matricryptic fragments and angiopoietin-2. Pericyte recruitment to such vascular tubes can prevent regression events by delivering molecules such as tissue inhibitor of metalloproteinase-3 and angiopoietin-1 that promote vascular stabilization by decreasing tube susceptibility to these regression stimuli.

SUMMARY

Extracellular matrix-derived signals lead to critical morphologic changes mediated through cytoskeletal rearrangements that control the shape, function and signaling events in endothelial cell-lined vessels regulating tube formation, remodeling, stabilization and regression. These signals control both vascular morphogenic and regression events, and thus a molecular balance exists to control the extent and function of vascular tube networks within tissues.

Pericellular hyaluronan coat visualized in live cells with a fluorescent probe is scaffolded by plasma membrane protrusions

Many cell types wear up to 20-mum-wide hyaluronidase-sensitive surface coats, detected by exclusion of sedimenting particles like fixed erythrocytes. The structure of the coat is enigmatic, being apparently too thick to be accounted by random coils or even extended chains of just hyaluronan attached to cell surface. We have shown that hyaluronan synthesis enforced by green fluorescent protein-hyaluronan synthase transfection creates microvillous protrusions. The idea that the plasma membrane protrusions rather than hyaluronan alone is responsible for the exclusion space was studied with a fluorescent probe for hyaluronan and a dye with membrane affinity, applied to live cell cultures. Mesothelial and smooth muscle cells, fibroblasts, and chondrocytes, all known for their endogenously active hyaluronan synthesis, showed hyaluronan-coated plasma membrane protrusions, barely visible in phase contrast microscopy. Treatment with hyaluronidase and inhibition of hyaluronan synthesis caused retraction of the protrusions unless they were attached to substratum. Hyaluronan and the exclusion space were reduced, but did not disappear, by purified hyaluronan hexasaccharides that compete with hyaluronan attached to CD44. The results suggest that slender plasma membrane protrusions are an inherent feature of hyaluronan coats, form their scaffold, and largely result from ongoing hyaluronan synthesis in their plasma membrane. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.

Hyaluronan-CD44 pathway regulates orientation of mitotic spindle in normal epithelial cells

Orientation of mitotic spindle and cell division axis can impact normal physiological processes, including epithelial tissue branching and neuron generation by asymmetric cell division. Microtubule dynamics and its interaction with cortical proteins regulate the orientation of mitotic spindle axis. However, the nature of extracellular signals that control proper orientation of mitotic spindle axis is largely unclear. Here, we show that signals from two distinct surface contact, "bi-surface-contact," sites are required for the orientation of mitotic spindle axis in normal epithelial cells. We identified apical and basal surface-membrane as required bi-surface-contact sites. We showed that high molecular weight (HMW) hyaluronan (HA)-CD44 signaling from the apical surface-membrane regulated the orientation of mitotic spindle axis to align parallel to the basal extracellular matrix (ECM). The same effect was achieved by fibronectin-integrin alphavbeta6 signaling from the basal surface-membrane or by inhibition of ROCK activity. On the contrary, HMW HA-CD44 signaling from the basal surface-membrane regulated the orientation of mitotic spindle axis to align oblique-perpendicular to the basal ECM. We also found that microtubule dynamics is required for HMW HA-CD44 mediated regulation of mitotic spindle orientation. Our findings thus provide a novel mechanism for the regulation of mitotic spindle orientation.

Hyaluronan constitutively regulates activation of COX-2-mediated cell survival activity in intestinal epithelial and colon carcinoma cells

Hyaluronan is a major component of the pericellular matrix surrounding tumor cells, including colon carcinomas. Elevated cycooxygenase-2 levels have been implicated in several malignant properties of colon cancer. We now show for the first time a strong link between hyaluronan-CD44 interaction and cyclooxygenase-2 in colon cancer cells. First, we have shown that increased expression of hyaluronan synthase-2 induces malignant cell properties, including increased proliferation, anchorage-independent growth, and epithelial-mesenchymal transition in HIEC6 cells. Second, constitutive hyaluronan-CD44 interaction stimulates a signaling pathway involving ErbB2, phosphoinositide 3-kinase/AKT, beta-catenin, and cyclooxygenase-2/prostaglandin E(2) in HCA7 colon carcinoma cells. Third, the HA/CD44-activated ErbB2 --> phosphoinositide 3-kinase/AKT --> beta-catenin pathway stimulates cell survival/cell proliferation through COX-2 induction in hyaluronan-overexpressing HIEC6 cells and in HCA7 cells. Fourth, perturbation of hyaluronan-CD44 interaction by hyaluronan oligomers or CD44-silencing RNA decreases cyclooxygenase-2 expression and enzyme activity, and inhibition of cyclooxygenase-2 decreases hyaluronan production suggesting the possibility of an amplifying positive feedback loop between hyaluronan and cyclooxygenase-2. We conclude that hyaluronan is an important endogenous regulator of colon cancer cell survival properties and that cyclooxygenase-2 is a major mediator of these hyaluronan-induced effects. Defining hyaluronan-dependent cyclooxygenase-2/prostaglandin E(2)-associated signaling pathways will provide a platform for developing novel therapeutic approaches for colon cancer.

Targeting hyaluronan interactions in malignant gliomas and their drug-resistant multipotent progenitors

PURPOSE

To determine if hyaluronan oligomers (o-HA) antagonize the malignant properties of glioma cells and treatment-resistant glioma side population (SP) cells in vitro and in vivo.

EXPERIMENTAL DESIGN

A single intratumoral injection of o-HA was given to rats bearing spinal cord gliomas 7 days after engraftment of C6 glioma cells. At 14 days, spinal cords were evaluated for tumor size, invasive patterns, proliferation, apoptosis, activation of Akt, and BCRP expression. C6SP were isolated by fluorescence-activated cell sorting and tested for the effects of o-HA on BCRP expression, activation of Akt and epidermal growth factor receptor, drug resistance, and glioma growth in vivo.

RESULTS

o-HA treatment decreased tumor cell proliferation, increased apoptosis, and down-regulated activation of Akt and the expression of BCRP. o-HA treatment of C6SP inhibited activation of epidermal growth factor receptor and Akt, decreased BCRP expression, and increased methotrexate cytotoxicity. In vivo, o-HA also suppressed the growth of gliomas that formed after engraftment of C6 or BCRP+ C6SP cells, although most C6SP cells lost their expression of BCRP when grown in vivo. Interestingly, the spinal cord gliomas contained many BCRP+ cells that were not C6 or C6SP cells but that expressed nestin and/or CD45; o-HA treatment significantly decreased the recruitment of these BCRP+ progenitor cells into the engrafted gliomas.

CONCLUSIONS

o-HA suppress glioma growth in vivo by enhancing apoptosis, down-regulating key cell survival mechanisms, and possibly by decreasing recruitment of host-derived BCRP+ progenitor cells. Thus, o-HA hold promise as a new biological therapy to inhibit HA-mediated malignant mechanisms in glioma cells and treatment-resistant glioma stem cells.

Hyaluronan, CD44 and Emmprin: partners in cancer cell chemoresistance

Hyaluronan not only is an important structural component of extracellular matrices but also interacts with cells during dynamic cell processes such as those occurring in cancer. Consequently, interactions of hyaluronan with tumor cells play important cooperative roles in various aspects of malignancy. Hyaluronan binds to several cell surface receptors, including CD44, thus leading to co-regulation of signaling pathways that are important in regulation of multidrug resistance to anticancer drugs, in particular anti-apoptotic pathways induced by activation of receptor tyrosine kinases. Emmprin, a cell surface glycoprotein of the Ig superfamily, stimulates hyaluronan production and downstream signaling consequences. Emmprin and CD44 also interact with various multidrug transporters of the ABC family and monocarboxylate transporters associated with resistance to cancer therapies. Moreover, hyaluronan-CD44 interactions are critical to these properties in the highly malignant, chemotherapy-resistant cancer stem-like cells. Perturbations of the hyaluronan-CD44 interaction at the plasma membrane by various antagonists result in attenuation of receptor tyrosine kinase and transporter activities and inhibition of tumor progression in vivo. These antagonists, especially small hyaluronan oligomers, may be useful in therapeutic strategies aimed at preventing tumor refractoriness or recurrence due to drug-resistant sub-populations within malignant cancers.

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.