The interaction of hyaluronate with the cell surface: the hyaluronate receptor and the core protein

Reprogramming of VEGF-mediated extracellular matrix changes through autocrine signaling

Vascular endothelial growth factor (VEGF) plays key roles in angiogenesis, vasculogenesis, and wound healing. In cancers, including triple negative breast cancer (TNBC), VEGF has been associated with increased invasion and metastasis, processes that require cancer cells to traverse through the extracellular matrix (ECM) and establish angiogenesis at distant sites. To further understand the role of VEGF in modifying the ECM, we characterized VEGF-mediated changes in the ECM of tumors derived from TNBC MDA-MB-231 cells engineered to overexpress VEGF. We established that increased VEGF expression by these cells resulted in tumors with reduced collagen 1 (Col1) fibers, fibronectin, and hyaluronan. Molecular characterization of tumors identified an increase of MMP1, uPAR, and LOX, and a decrease of MMP2, and ADAMTS1. α-SMA, a marker of cancer associated fibroblasts (CAFs), increased, and FAP-α, a marker of a subset of CAFs associated with immune suppression, decreased with VEGF overexpression. Analysis of human data from The Cancer Genome Atlas Program confirmed mRNA differences for several molecules when comparing TNBC with high and low VEGF expression. We additionally characterized enzymatic changes induced by VEGF overexpression in three different cancer cell lines that clearly identified autocrine-mediated changes, specifically uPAR, in these enzymes. Unlike the increase of Col1 fibers and fibronectin mediated by VEGF during wound healing, in the TNBC model, VEGF significantly reduced key protein components of the ECM. These results further expand our understanding of the role of VEGF in cancer progression and identify potential ECM-related targets to disrupt this progression.

The Labeling, Visualization, and Quantification of Hyaluronan Distribution in Tumor-Bearing Mouse Using PET and MR Imaging

PURPOSE

Hyaluronan (HA) based biomaterials are widely used as tissue scaffolds, drug formulations, as well as targeting ligands and imaging probes for diagnosis and drug delivery. However, because of the presence of abundant endogenous HA presented in various tissues in vivo, the pharmacokinetic behavior and biodistribution patterns of exogenously administered HAs have not been well characterized.

METHODS

The HA backbone was modified with Diethylenetriamine (DTPA) to enable the chelation of gadolinium (Gd) and aluminum (Al) ions. Series of PET and MR imaging were taken after the injection of HA-DTPA-Gd and HA-DTPA-Al¹⁸F while using¹⁸F-FDG and Magnevist(DTPA-Gd) as controls. The Tomographic images were analyzed and quantified to reveal the distribution and locations of HA in tumor-bearing mice.

RESULTS

The labeled HAs had good stability in plasma. They retained binding affinity towards CD44s on tumor cell surface. The injected HAs distributed widely in various organs, but were found to be cleared quickly except inside tumor tissues where the signals were higher and persisted longer.

CONCLUSION

Medical imaging tools, including MR and PET, can be highly valuable for examining biomaterial distribution non-invasively. The HA tumor accumulation properties may be explored for the development of active targeting drug carriers and molecular probes.

MicroRNA-146a downregulates the production of hyaluronic acid and collagen I in Graves' ophthalmopathy orbital fibroblasts

The present study aimed to investigate the effect of microRNA (miR)-146a on the secretion of hyaluronic acid (HA) and collagen I in Graves' ophthalmopathy (GO) orbital fibroblasts, and identify potential novel targets for the clinical treatment of GO. Orbital fibroblasts were extracted from orbital connective tissue, and primary cells were identified via immunohistochemistry. The levels of HA and collagen I in orbital fibroblasts of non-GO controls and patients with GO were examined via reverse transcription-quantitative PCR (RT-qPCR). miR-146a was overexpressed or inhibited in primary orbital fibroblasts via lentiviral infection, and the levels of HA and collagen I following miR-146a overexpression or inhibition were detected via ELISA and RT-qPCR. The results indicated that the mRNA expression of HA and collagen I was higher in orbital fibroblasts from patients with GO compared with the non-GO cohort. Overexpression of miR-146a reduced, and inhibition of miR-146a increased the production of HA and collagen I in GO orbital fibroblasts. In conclusion, it was demonstrated that miR-146a downregulated the secretion of HA and collagen I in GO orbital fibroblasts in vitro, which may affect glycosaminoglycan aggregation and collagen deposition in GO.

Polysaccharide Multilayer Films in Sensors for Detecting Prostate Tumor Cells Based on Hyaluronan-CD44 Interactions

The increasing need for point-of-care diagnosis has sparked the development of label-free sensing platforms, some of which are based on impedance measurements with biological cells. Here, interdigitated electrodes were functionalized with layer-by-layer (LbL) films of hyaluronan (HA) and chitosan (CHI) to detect prostatic tumor cells (PC3 line). The deposition of LbL films was confirmed with atomic force microscopy and polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), which featured the vibrational modes of the HA top layer capable of interacting specifically with glycoprotein CD44 receptors overexpressed in tumor cells. Though the CHI/HA LbL films cannot be considered as a traditional biosensor due to their limited selectivity, it was possible to distinguish prostate tumor cells in the range from 50 to 600 cells/µL in in vitro experiments with impedance spectroscopy. This was achieved by treating the impedance data with information visualization methods, which confirmed the distinguishing ability of the films by observing the absence of false positives in a series of control experiments. The CD44–HA interactions may, therefore, be exploited in clinical analyses and point-of-care diagnostics for cancer, particularly if computational methods are used to process the data.

CD44 mediates the catch-bond activated rolling of HEPG2Iso epithelial cancer cells on hyaluronan

The attachment of cancer cells to the endothelium is an essential step during metastatic dissemination. The cell surface receptor CD44 is capable of binding to hyaluronan (HA) produced by tumor cells and by cells of the tumor microenvironment, including blood endothelial cells. Here, we investigated the role of CD44 in the interaction between the liver cancer cell line HepG2Iso and HA surfaces. The rolling interaction was quantitatively analyzed using a microfluidic shear force setup. It was found that rolling of the liver cancer cells on HA depends on CD44, which mediates a catch-bond interaction and thus a flow-induced rolling of the cells. Reduction of CD44 expression by means of siRNA, inhibition of the interaction of CD44 with HA by antibody blocking, and treatment with low molecular weight HA inhibited liver cancer cell rolling on HA-coated surfaces. The results not only clearly show the dependency of the shear-induced catch-bond interaction of HepG2Iso cells on CD44 and HA, but also for the first time demonstrate CD44-mediated rolling for epithelium-derived cells that are typically adherent.

Sodium hyaluronate eye drops treatment for superficial corneal abrasion caused by mechanical damage: a randomized clinical trial in the People's Republic of China

PURPOSE

To evaluate the effectiveness and safety of 0.3% sodium hyaluronate (HA) compared to recombinant bovine basic fibroblast growth factor (rb-bFGF) for the treatment of corneal epithelial abrasion caused by mechanical damage in Chinese patients.

METHODS

Thirty patients were randomly assigned to the HA or rb-bFGF treatment group. The HA group was treated with 0.3% HA and 0.5% levofloxacin, and the rb-bFGF group was treated with topical rb-bFGF and 0.5% levofloxacin. The primary endpoint was the clinical effectiveness rates at day 3. Secondary endpoints were the dimensions of the wound area and the percentage of wound closure.

RESULTS

After 3 days of treatment, the clinical effectiveness rates of the HA group and the rb-bFGF group were 86.67% (13/15) and 93.33% (14/15), respectively. The dimensions of the wound area were reduced from 9.83±8.50 to 0.02±0.06 mm(2) for the HA group at day 7, and from 10.58±9.94 to 0.02±0.07 mm(2) for the rb-bFGF group. At day 3, the wound closure was almost complete in both groups; 94.73% in the HA group compared to 95.77% in the rb-bFGF group (P>0.05).

CONCLUSION

Topical 0.3% HA provided a promising treatment for superficial corneal abrasion caused by mechanical damage in a manner similar to rb-bFGF.

Hyaluronan fragments as mediators of inflammation in allergic pulmonary disease

Asthma is frequently caused and/or exacerbated by sensitization to allergens, which are ubiquitous in many indoor and outdoor environments. Severe asthma is characterized by airway hyperresponsiveness and bronchial constriction in response to an inhaled allergen, leading to a disease course that is often very difficult to treat with standard asthma therapies. As a result of interactions among inflammatory cells, structural cells, and the intercellular matrix of the allergic lung, patients with sensitization to allergens may experience a greater degree of tissue injury followed by airway wall remodeling and progressive, accumulated pulmonary dysfunction as part of the disease sequela. In addition, turnover of extracellular matrix (ECM) components is a hallmark of tissue injury and repair. This review focuses on the role of the glycosaminoglycan hyaluronan (HA), a component of the ECM, in pulmonary injury and repair with an emphasis on allergic asthma. Both the synthesis and degradation of the ECM are critical contributors to tissue repair and remodeling. Fragmented HA accumulates during tissue injury and functions in ways distinct from the larger native polymer. There is gathering evidence that HA degradation products are active participants in stimulating the expression of inflammatory genes in a variety of immune cells at the injury site. In this review, we will consider recent advances in the understanding of the mechanisms that are associated with HA accumulation and inflammatory cell recruitment in the asthmatic lung.

Stimulation of TLR4 by LMW-HA induces metastasis in human papillary thyroid carcinoma through CXCR7

In inflammatory sites, high molecular weight hyaluronan fragments are degraded into lower molecular weight hyaluronan fragments (LMW-HA) to regulate immune responses. However, the function of LMW-HA in PTC progression remains to be elucidated. In this study, we found that receptor of LMW-HA, TLR4, was aberrantly overexpressed in PTC tissues and cell line W3. Exposure of W3 cells to LMW-HA promoted cell proliferation and migration via TLR4. Knockdown of TLR4 has provided evidence that TLR4 is essential for LMW-HA-induced CXCR7 expression, which is responsible for LMW-HA-induced proliferation and migration of W3 cells. In tumor-bearing adult nude mice, stimulation of LMW-HA on W3 cells promotes CXCR7 expression in tumor masses (P = 0.002) and tumor growth (P < 0.001). To further confirm our findings, we investigated the clinicopathologic significance of TLR4 and CXCR7 expression using immumohistochemistry in 135 human PTC tissues and 56 normal thyroid tissue samples. Higher rates of TLR4 (53%) and CXCR7 (24%) expression were found in PTC tissues than in normal tissues. Expression of TLR4 or CXCR7 is associated with tumor size and lymph node metastasis. Therefore, LMW-HA may contribute to the development of PTC via TLR4/CXCR7 pathway, which may be a novel target for PTC immunomodulatory therapy.

The interaction between LYVE-1 with hyaluronan on the cell surface may play a role in the diversity of adhesion to cancer cells

Hyaluronan (HA), a simple disaccharide unit, can polymerize and is considered a primary component of the extracellular matrix, which has a wide range of biological functions. In recent years, HA was found on the surface of tumor cells. According to previous reports, differing HA content on the cell surface of tumor cells is closely related to lymph node metastases, but the mechanisms mediating this process remained unclear. This research intended to study the surface content of HA on tumor cells and analyze cell adhesive changes caused by the interaction between HA and its lymphatic endothelial receptor (LYVE-1). We screened and observed high HA content on HS-578T breast cells and low HA content on MCF-7 breast cells through particle exclusion, immunofluorescence and flow cytometry experiments. The expression of LYVE-1, the lymph-vessel specific HA receptor, was consistent with our previous report and enhanced the adhesion of HA^high-HS-578T cells to COS-7^LYVE-1(+) through HA in cell static adhesion and dynamic parallel plate flow chamber experiments. MCF-7 breast cells contain little HA on the surface; however, our results showed little adhesion difference between MCF-7 cells and COS-7^LYVE-1(+) and COS-7^LYVE-1(−) cells. Similar results were observed concerning the adhesion of HS-578T cells or MCF-7 cells to SVEC4-10 cells. Furthermore, we observed for the first time that the cell surface HA content of high transfer tumor cells was rich, and we visualized the cross-linking of HA cable structures, which may activate LYVE-1 on lymphatic endothelial cells, promoting tumor adhesion. In summary, high-low cell surface HA content of tumor cells through the interaction with LYVE-1 leads to adhesion differences.

Synthesis and selective cytotoxicity of a hyaluronic acid-antitumor bioconjugate

A cell-targeted prodrug was developed for the anti-cancer drug Taxol, using hyaluronic acid (HA) as the drug carrier. HA-Taxol bioconjugates were synthesized by linking the Taxol 2'-OH via a succinate ester to adipic dihydrazide-modified HA (HA-ADH). The coupling of Taxol-NHS ester and HA-ADH provided several HA bioconjugates with different levels of ADH modification and different Taxol loadings. A fluorescent BODIPY-HA was also synthesized to illustrate cell targeting and uptake of chemically modified HA using confocal microscopy. HA-Taxol conjugates showed selective toxicity toward the human cancer cell lines (breast, colon, and ovarian) that are known to overexpress HA receptors, while no toxicity was observed toward a mouse fibroblast cell line at the same concentrations used with the cancer cells. The drug carrier HA-ADH was completely nontoxic. The selective cytotoxicity is consistent with the results from confocal microscopy, which demonstrated that BODIPY-HA only entered the cancer cell lines.

Cell surface glycoconjugates and the extracellular matrix of the developing mouse embryo epicardium

Cell surface glycoconjugates and the extracellular matrix (ECM) of the proepicardium and the developing epicardium were studied in early mouse embryos by light and electron microscopy with histochaemical and immunocytochaemical techniques. The extracardially located proepicardium consists of polarized mesothelial cells forming the proepicardial vesicles. These vesicles contain a fine proteoglycan network and an acellular ECM rich in hyaluronic acid. Membrane-bound glycoconjugates are shown with cuprolinic blue, alcian blue and ruthenium red on the apical (outer) cell surface, while fibronectin and laminin are present on the basal (luminal) cell surface. These membrane and matrix components of the proepicardium might be involved in specific attachment of proepicardial cells to the bare heart tube and might facilitate the initial migration of epicardial cells over the myocardial surface. In the cell coat of the cardiomyocytes of the bare heart tube the fibronectin and laminin are concentrated in patches. The formation of the epicardial covering is a rapid process, requiring only about 2 days (9-11 days) to ensheath the entire heart tube from the inflow to the outflow segment. The subepicardial matrix between the newly formed epicardial covering and myocardial layer is acellular at first, but contains a condensing proteoglycan network, membrane and matrix fibronectin, type IV collagen and laminin on the myocardial cell surface. The formation and the distribution of the subepicardial ECM show regional characteristics. The accumulating ECM forms wide subepicardial spaces and protuberances in the atrioventricular and interventricular sulci. The sulci of the heart seem to provide the optimum microenvironment for haematopoiesis and vasculogenesis. Haematopoietic islands and coronary vessel forerunners appear and concentrate in the regularly spaced surface protuberances. The vasculogenesis proceeds from the inflow to the outflow segment of the heart. The first blood capillaries appear in the sinoatrial sulcus of the 10-day embryo. By 11-13 days the subepicardial blood vessels form an interconnected network and establish the coronary artery orifices.

Assembly of pericellular matrices by COS-7 cells transfected with CD44 lymphocyte-homing receptor genes

The capacity to assemble and retain a pericellular matrix is correlated with the expression of the cell surface binding sites specific for the extracellular matrix macromolecule hyaluronan. These binding proteins have been termed hyaluronan receptors. The lymphocyte-homing receptor CD44 may have identity with these hyaluronan receptors. To determine whether hyaluronan receptors function independently in this capacity for matrix assembly, mammalian cells were transfected with cDNA encoding the putative hyaluronan receptor CD44. After transfection with CD44 cDNA, COS cells gained the capacity to assemble hyaluronan-dependent pericellular matrices in the presence of exogenously added hyaluronan and proteoglycan. Thus, CD44 receptors do function as matrix-organizing, matrix-anchoring hyaluronan-binding proteins. In addition, the expression of CD44/hyaluronan receptors alone is sufficient to direct this matrix assembly. If matrix assembly is a function of cells in vivo that express hyaluronan receptors, this raises interesting possibilities for the role of the receptors in cell migration, when new extracellular matrix environments are encountered.

Effects of hyaluronic acid on macrophage phagocytosis and active oxygen release

The effects of hyaluronic acid (HA) on macrophage function, in terms of the phagocytosis of latex beads and superoxide anion and hydrogen peroxide release stimulated by phorbol myristate acetate (PMA), were studied in guinea-pig peritoneal macrophages. Phagocytosis was inhibited in a dose- and molecular-weight-dependent manner by HA. The addition of PMA to the culture, at a dose of more than 10 ng ml-1, caused an increase in the release of active oxygens. The release of active oxygens was inhibited by high molecular weight HA (MW 2.02 x 10(6), HA-202) in a dose-dependent manner. In cell-free systems, HA-202 had a negligible effect in scavenging these active oxygens. Of the three molecular sizes of HA (MW: 0.28 x 10(6), 0.98 x 10(6) and 2.02 x 10(6)), HA-202 most strongly inhibited the active oxygen release. These results indicate that high-molecular-weight HA acts directly on macrophages to inhibit phagocytosis and active oxygen formation, which, in turn, ameliorates the progression of chronic inflammation.

Endocytosis of hyaluronan in rat Kupffer cells

The binding, uptake and degradation of hyaluronan (HA) labelled with 3H in its acetyl group were studied in cultured rat Kupffer cells (KC). At 4 degrees C the binding increased with increasing concentrations of HA in the culture medium up to at least 1 microgram/ml, when saturation occurred. Binding could be prevented efficiently by the addition of an excess of unlabelled HA, and to a lesser extent by chondroitin sulphate and oligosaccharide fragments of HA, consisting of four sugars or more. The labelled HA bound to the cells could be removed by incubating the cells with Streptomyces hyaluronidase, or trypsin, indicating that the HA-binding sites are located on the cell surface. At 37 degrees C HA was internalized in a concentration-dependent manner, and degradation products appeared in the supernatant after 1-5 h, depending on the concentration applied. At 50 ng of free HA/ml, each KC accumulated 60 ag of the polysaccharide/min in the first 1 h, and degraded a total amount of 10 fg of HA during an 8 h period. Addition of the negatively charged polysaccharide dextran sulphate reduced binding, and to an even greater extent internalization, of HA in KC, while no effect was observed with dextran. Depletion of intracellular potassium caused a marked reduction in the rate of endocytosis of cell-membrane-associated HA into KC, without affecting binding. Addition of KCl to the culture medium returned endocytosis of [3H]HA to normal levels. There was no effect on binding and a partial effect on internalization by depletion of bivalent cations or in the presence of EDTA. The degradation of [3H]HA by KC cultures was abolished in the presence of weak bases, NH4Cl and chloroquine, supporting the idea that HA is endocytosed into lysosomes prior to degradation. The fluid-phase marker [14C]sucrose was internalized in the cells at much lower rate than was HA. Rates of binding, internalization and degradation of HA in KC point therefore to a specific endocytosis followed by an intracellular degradation to low-M(r) compounds. It was estimated that, under physiological conditions, KC only clear a minor proportion of circulating HA.

The hyaluronan receptor (CD44) participates in the uptake and degradation of hyaluronan

The hyaluronan receptor belongs to the polymorphic family of CD44 glycoproteins, which have been implicated in a variety of cellular functions including adhesion to hyaluronan and collagen, the binding of lymphocytes to high endothelial cells during extravasation, and conferring metastatic potential to carcinoma cells. Here, we demonstrate that the receptor also participates in the uptake and degradation of hyaluronan by both transformed fibroblasts (SV-3T3 cells) and alveolar macrophages. These cells were incubated with isotopically labeled hyaluronan for various periods of time, and the extent of degradation was determined by either molecular-sieve chromatography or centrifugation through Centricon 30 microconcentrators. The macrophages degraded the hyaluronan at a faster rate than the SV-3T3 cells, which may reflect the fact that they contained a greater number of receptors. More importantly, in both cell types, the degradation of hyaluronan was specifically blocked by antibodies directed against the receptor. However, the receptor by itself did not have the ability to degrade hyaluronan, since preparations of SV-3T3 membranes containing the receptor did not break down hyaluronan. Subsequent experiments revealed that macrophages can internalize fluorescein-tagged hyaluronan, and this process was blocked by antibodies against the receptor. Furthermore, the subsequent degradation of hyaluronan was inhibited by agents that block the acidification of lysosomes (chloroquine and NH4Cl). Thus, the most likely explanation for these results is that the receptor mediates the uptake of hyaluronan into the cell where it can be degraded by acid hydrolases in lysosomes. The ability of cells expressing the receptor to degrade hyaluronan may be important during tissue morphogenesis and cell migration.

Distinct effects of two CD44 isoforms on tumor growth in vivo

Tumor growth is dependent in part on interactions between tumor cells and the extracellular matrix of host tissues. Expression of the cell surface glycoprotein CD44/Pgp-1, which mediates cell-substrate interactions is increased in many types of malignancies, but the role of CD44 in tumor growth is largely undefined. Recently, two isoforms of CD44 have been identified: an 80-90 kD form, which has high affinity for cell bound hyaluronate and a 150 kD form which does not mediate attachment to hyaluronate-coated surfaces. In this work, human B cell lymphoma cells stably transfected with cDNA clones encoding either of the two CD44 isoforms were compared for tumorigenicity and metastatic potential in nude mice. Expression of the 80-90 kD form but not the 150 kD form of CD44 greatly enhanced both local tumor formation and metastatic proclivity of the lymphoma cells. Our results suggest that CD44 polypeptides may play an important role in regulating primary and metastatic tumor development in vivo.

Purification and characterization of a hyaluronan-binding protein from rat chondrosarcoma

Swarm rat chondrosarcoma contains a hyaluronan-binding protein of molecular mass 102 kDa (HABP102). The protein is present in 4 M-guanidinium chloride extracts of the chondrosarcoma and can be incorporated into reconstituted proteoglycan aggregates, but it is not present in native proteoglycan aggregates or in 0.5 M-guanidinium chloride extracts. HABP102 is unlikely to be an integral membrane protein, as it does not require detergent for extraction, is not enriched in hydrophobic amino acids and does not bind avidly to octyl-Sepharose. The protein stains poorly with Coomassie Blue and is only visible on PAGE gels after staining with silver. Disulphide bonds are essential for the binding of HABP102 to hyaluronan, and bivalent cations are not required for this interaction. HABP102 can be purified from dissociative chondrosarcoma extracts by sequential density-gradient centrifugation, hyaluronan-Sepharose affinity chromatography and hydrophobic-interaction chromatography. The amino acid composition is similar to that of domains 1-4 of the chondrosarcoma proteoglycan core protein, but peptide analysis after digestion with Staphylococcus aureus V8 proteinase and chymotrypsin and different immunoreactivity suggest that HABP102 is not closely related to proteoglycan hyaluronan-binding region. HABP102 is a glycoprotein containing N-acetylgalactosamine, N-acetylglucosamine, mannose and galactose.