Characterization of the murine gene encoding the hyaluronan receptor RHAMM

Enhanced Transdermal Absorption of Hyaluronic Acid via Fusion with Pep-1 and a Hyaluronic Acid Binding Peptide

It is always big challenges for hyaluronic acid (HA) in transmembrane absorbing and efficient delivering to the skin. Pep-1, as one of the cell-penetrating peptides, has been documented to permeate various substances across cellular membranes without covalent binding. Here, a novel hyaluronic acid binding peptide (named HaBP) is designed, and then combined with Pep-1 to enhance the cell-penetrating efficiency of HA. The results of ELISA and immunofluorescence assay show that HaBP could bind with HA very well, and a combination of Pep-1 and HaBP could efficiently improve the transmembrane ability of HA. Furthermore, HA gradually enters the dermis from the surface of the skin in mice when it is administrated with both HaBP and Pep-1, while there are no obvious allergies or other adverse reactions during this process. This study finds a new method to promote the efficient transmembrane and transdermal absorption of HA, and throws some light on further research on the development of hyaluronic acid and its related cosmetics or drugs.

Targeting Hyaluronic Acid and Peritoneal Dissemination in Colorectal Cancer

Peritoneal metastasis (PM) from colorectal cancer (CRC) carries a significant mortality rate for patients and treatment is challenging. The development of PM is a multistep process involving detachment, adhesion, invasion and colonization of the peritoneal cavity. Cytoreductive surgery and HIPEC (hyperthermic intraperitoneal chemotherapy) for PM from CRC has some benefit but overall survival is poor and recurrence rates are high. Treatments to prevent the development of peritoneal metastasis could have the potential to improve CRC survival and disease-free outcomes. The ability of cancer cells to invade the peritoneum and become established as metastatic tumors is influenced by a multifactorial process. Hyaluronic acid (HA) has been shown to coat the mesothelial cells of the peritoneum and has been demonstrated to be utilized in various malignancies as part of the metastatic process in peritoneal dissemination. CD44, RHAMM (CD168) and ICAM-1 have all been shown to be binding partners for HA. Targeting HA-mediated binding may prevent adhesion to distant sites within the peritoneum through suppression of interaction of these molecules. Here we review the current literature and discuss key molecules involved with PM dissemination, with the potential to target these mechanisms in the delivery of future treatments.

RHAMM Is a Multifunctional Protein That Regulates Cancer Progression

The functional complexity of higher organisms is not easily accounted for by the size of their genomes. Rather, complexity appears to be generated by transcriptional, translational, and post-translational mechanisms and tissue organization that produces a context-dependent response of cells to specific stimuli. One property of gene products that likely increases the ability of cells to respond to stimuli with complexity is the multifunctionality of expressed proteins. Receptor for hyaluronan-mediated motility (RHAMM) is an example of a multifunctional protein that controls differential responses of cells in response-to-injury contexts. Here, we trace its evolution into a sensor-transducer of tissue injury signals in higher organisms through the detection of hyaluronan (HA) that accumulates in injured microenvironments. Our goal is to highlight the domain and isoform structures that generate RHAMM's function complexity and model approaches for targeting its key functions to control cancer progression.

Decellularized peripheral nerve grafts by a modified protocol for repair of rat sciatic nerve injury

Studies have shown that acellular nerve xenografts do not require immunosuppression and use of acellular nerve xenografts for repair of peripheral nerve injury is safe and effective. However, there is currently no widely accepted standard chemical decellularization method. The purpose of this study is to investigate the efficiency of bovine-derived nerves decellularized by the modified Hudson’s protocol in the repair of rat sciatic nerve injury. In the modified Hudson’s protocol, Triton X-200 was replaced by Triton X-100, and DNase and RNase were used to prepare accelular nerve xenografts. The efficiency of bovine-derived nerves decellularized by the modified Hudson’s protocol was tested in vitro by hematoxylin & eosin, Alcian blue, Masson’s trichrome, and Luxol fast blue staining, immunohistochemistry, and biochemical assays. The decellularization approach excluded cells, myelin, and axons of nerve xenografts, without affecting the organization of nerve xenografts. The decellularized nerve xenograft was used to bridge a 7 mm-long sciatic nerve defect to evaluate its efficiency in the repair of peripheral nerve injury. At 8 weeks after transplantation, sciatic function index in rats subjected to transplantation of acellular nerve xenograft was similar to that in rats undergoing transplantation of nerve allograft. Morphological analysis revealed that there were a large amount of regenerated myelinated axons in acellular nerve xenograft; the number of Schwann cells in the acellular nerve xenograft was similar to that in the nerve allograft. These findings suggest that acellular nerve xenografts prepared by the modified Hudson’s protocol can be used for repair of peripheral nerve injury. This study was approved by the Research Ethics Committee, Research and Technology Chancellor of Guilan University of Medical Sciences, Iran (approval No. IR.GUMS.REC.1395.332) on February 11, 2017.

Cell-specific expression of the transcriptional regulator RHAMM provides a timing mechanism that controls appropriate wound re-epithelialization

Prevention of aberrant cutaneous wound repair and appropriate regeneration of an intact and functional integument require the coordinated timing of fibroblast and keratinocyte migration. Here, we identified a mechanism whereby opposing cell-specific motogenic functions of a multifunctional intracellular and extracellular protein, the receptor for hyaluronan-mediated motility (RHAMM), coordinates fibroblast and keratinocyte migration speed and ensures appropriate timing of excisional wound closure. We found that, unlike in WT mice, in Rhamm-null mice, keratinocyte migration initiates prematurely in the excisional wounds, resulting in wounds that have re-surfaced before the formation of normal granulation tissue, leading to a defective epidermal architecture. We also noted aberrant keratinocyte and fibroblast migration in the Rhamm-null mice, indicating that RHAMM suppresses keratinocyte motility but increases fibroblast motility. This cell context-dependent effect resulted from cell-specific regulation of extracellular signal-regulated kinase 1/2 (ERK1/2) activation and expression of a RHAMM target gene encoding matrix metalloprotease 9 (MMP-9). In fibroblasts, RHAMM promoted ERK1/2 activation and MMP-9 expression, whereas in keratinocytes, RHAMM suppressed these activities. In keratinocytes, loss of RHAMM function or expression promoted epidermal growth factor receptor-regulated MMP-9 expression via ERK1/2, which resulted in cleavage of the ectodomain of the RHAMM partner protein CD44 and thereby increased keratinocyte motility. These results identify RHAMM as a key factor that integrates the timing of wound repair by controlling cell migration.

Matrix Hyaluronan-CD44 Interaction Activates MicroRNA and LncRNA Signaling Associated With Chemoresistance, Invasion, and Tumor Progression

Tumor malignancies involve cancer cell growth, issue invasion, metastasis and often drug resistance. A great deal of effort has been placed on searching for unique molecule(s) overexpressed in cancer cells that correlate(s) with tumor cell-specific behaviors. Hyaluronan (HA), one of the major ECM (extracellular matrix) components have been identified as a physiological ligand for surface CD44 isoforms which are frequently overexpressed in malignant tumor cells during cancer progression. The binding interaction between HA and CD44 isoforms often stimulates aberrant cellular signaling processes and appears to be responsible for the induction of multiple oncogenic events required for cancer-specific phenotypes and behaviors. In recent years, both microRNAs (miRNAs) (with ~20–25 nucleotides) and long non-coding RNAs (lncRNAs) (with ~200 nucleotides) have been found to be abnormally expressed in cancer cells and actively participate in numerous oncogenic signaling events needed for tumor cell-specific functions. In this review, I plan to place a special emphasis on HA/CD44-induced signaling pathways and the presence of several novel miRNAs (e.g., miR-10b/miR-302/miR-21) and lncRNAs (e.g., UCA1) together with their target functions (e.g., tumor cell migration, invasion, and chemoresistance) during cancer development and progression. I believe that important information can be obtained from these studies on HA/CD44-activated miRNAs and lncRNA that may be very valuable for the future development of innovative therapeutic drugs for the treatment of matrix HA/CD44-mediated cancers.

Prognostic significance of receptor for hyaluronan acid-mediated motility (CD168) in acute pediatric leukemias - assessment of clinical outcome, post induction, end of treatment and minimal residual disease

INTRODUCTION

The extracellular matrix protein hyaluronan acid plays an active in role in tumor cell proliferation and invasion. Hyaluronan acid receptors, namely CD168 or the receptor for hyaluronan acid-mediated motility (RHAMM) and CD44 have been implicated in promoting malignancy. There is a lacuna in data on the expression of the receptor in pediatric leukemias.

METHODS

Pediatric patients with acute leukemia who were diagnosed, treated and followed up in our center were enrolled. The bone marrow biopsies performed prior to treatment were subjected to immunohistochemical staining (54 biopsies: acute lymphoblastic leukemia - 45, acute myeloid leukemia - 9). Blast counts were carried out at diagnosis, end of the induction phase and end of chemotherapy, the minimal residual disease was assessed and follow up details were collected. Positivity was correlated with initial blast count, post-induction blast count, minimal residual disease and patient survival.

RESULTS

There was no correlation between the initial blast count and the percentage of blasts with RHAMM expression. The positive correlation between percentage of blasts expressing RHAMM and the post-induction blast count was moderate in acute myeloid leukemia (0.74) and mild in acute lymphoblastic leukemia (0.48). There was a statistically significant difference in RHAMM expression between the two minimal residual disease risk groups (p-value = 0.012) with a negative prognostic effect of RHAMM expression. Moreover, a negative prognostic effect of RHAMM expression was noted when patient survival was considered.

CONCLUSION

This study shows that blasts in acute myeloid leukemia show more RHAMM positivity than those of acute lymphoblastic leukemia indicating the aggressive nature of this type of leukemia. In acute leukemias, patients with high percentages of RHAMM-positive blasts had more post-induction blasts, blasts in minimal residual disease and poorer prognosis.

Interactions between Hyaluronan and Its Receptors (CD44, RHAMM) Regulate the Activities of Inflammation and Cancer

The glycosaminoglycan hyaluronan (HA), a major component of extracellular matrices, and cell surface receptors of HA have been proposed to have pivotal roles in cell proliferation, migration, and invasion, which are necessary for inflammation and cancer progression. CD44 and receptor for HA-mediated motility (RHAMM) are the two main HA-receptors whose biological functions in human and murine inflammations and tumor cells have been investigated comprehensively. HA was initially considered to be only an inert component of connective tissues, but is now known as a “dynamic” molecule with a constant turnover in many tissues through rapid metabolism that involves HA molecules of various sizes: high molecular weight HA (HMW HA), low molecular weight HA, and oligosaccharides. The intracellular signaling pathways initiated by HA interactions with CD44 and RHAMM that lead to inflammatory and tumorigenic responses are complex. Interestingly, these molecules have dual functions in inflammations and tumorigenesis. For example, the presence of CD44 is involved in initiation of arthritis, while the absence of CD44 by genetic deletion in an arthritis mouse model increases rather than decreases disease severity. Similar dual functions of CD44 exist in initiation and progression of cancer. RHAMM overexpression is most commonly linked to cancer progression, whereas loss of RHAMM is associated with malignant peripheral nerve sheath tumor growth. HA may similarly perform dual functions. An abundance of HMW HA can promote malignant cell proliferation and development of cancer, whereas antagonists to HA-CD44 signaling inhibit tumor cell growth in vitro and in vivo by interfering with HMW HA-CD44 interaction. This review describes the roles of HA interactions with CD44 and RHAMM in inflammatory responses and tumor development/progression, and how therapeutic strategies that block these key inflammatory/tumorigenic processes may be developed in rodent and human diseases.

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.

Role of receptor for hyaluronan-mediated motility (RHAMM) in human head and neck cancers

The receptor for hyaluronan (HA)-mediated motility (RHAMM) is a HA-binding protein located in the cytoskeleton and centrosome. RHAMM has multiple functions that manifest with different cellular localizations, for example, modulation of growth factor receptor, regulation of cell signaling pathways, and mitotic spindle assembly. In addition, its increased expression has major roles in tumorigenesis and can induce genomic instability and cancer progression. In head and neck cancers, increased expression of RHAMM is associated with high proliferation of cancer cells and decreased survival. CD44, a cell-adhesion molecule and HA receptor, can modulate intracellular signaling by forming complexes with RHAMM to promote invasion and metastasis of cancer cells. In this review, we provide an overview of the biological functions of RHAMM in non-neoplastic cells and cancer cells, as well as its association with CD44, and also introduce studies that particularly implicate RHAMM in the pathogenesis of head and neck cancers.

Toll-like receptor 2 (TLR2), transforming growth factor-β, hyaluronan (HA), and receptor for HA-mediated motility (RHAMM) are required for surfactant protein A-stimulated macrophage chemotaxis

The innate immune system protects the host from bacterial and viral invasion. Surfactant protein A (SPA), a lung-specific collectin, stimulates macrophage chemotaxis. However, the mechanisms regulating this function are unknown. Hyaluronan (HA) and its receptors RHAMM (receptor for HA-mediated motility, CD168) and CD44 also regulate cell migration and inflammation. We therefore examined the role of HA, RHAMM, and CD44 in SPA-stimulated macrophage chemotaxis. Using antibody blockade and murine macrophages, SPA-stimulated macrophage chemotaxis was dependent on TLR2 but not the other SPA receptors examined. Anti-TLR2 blocked SPA-induced production of TGFβ. In turn, TGFβ1-stimulated chemotaxis was inhibited by HA-binding peptide and anti-RHAMM antibody but not anti-TLR2 antibody. Macrophages from TLR2(-/-) mice failed to migrate in response to SPA but responded normally to TGFβ1 and HA, effects that were blocked by anti-RHAMM antibody. Macrophages from WT and CD44(-/-) mice had similar responses to SPA, whereas those from RHAMM(-/-) mice had decreased chemotaxis to SPA, TGFβ1, and HA. In primary macrophages, SPA-stimulated TGFβ production was dependent on TLR2, JNK, and ERK but not p38. Pam3Cys, a specific TLR2 agonist, stimulated phosphorylation of JNK, ERK, and p38, but only JNK and ERK inhibition blocked Pam3Cys-stimulated chemotaxis. We have uncovered a novel pathway for SPA-stimulated macrophage chemotaxis where SPA stimulation via TLR2 drives JNK- and ERK-dependent TGFβ production. TGFβ1, in turn, stimulates macrophage chemotaxis in a RHAMM and HA-dependent manner. These findings are highly relevant to the regulation of innate immune responses by SPA with key roles for specific components of the extracellular matrix.

Overexpression of receptor for hyaluronan-mediated motility (RHAMM) in MC3T3-E1 cells induces proliferation and differentiation through phosphorylation of ERK1/2

Receptor for hyaluronan (HA)-mediated motility (RHAMM) was first described as a soluble HA binding protein released by sub-confluent migrating cells. We previously found that RHAMM was highly expressed and plays an important role in proliferation in the human cementifying fibroma (HCF) cell line, which we previously established. HCF is a benign fibro-osseous neoplasm of the jaw and is composed of fibrous tissue containing varying amounts of mineralized material. However, the pathogenesis of HCF is not clear. In this paper, we examined the roles of RHAMM in osteoblastic cells. We generated RHAMM-overexpressing MC3T3-E1 cells and examined the cell proliferation and differentiation of osteoblastic cells. In MC3T3-E1 cells, overexpressing RHAMM was located intracellular and activated ERK1/2. Interestingly, the ERK1/2 activated by RHAMM overexpression promoted cell proliferation and suppressed the differentiation of osteoblastic cells. Our findings strongly suggest that RHAMM may play a key role in the osteoblastic differentiation process. The rupture of balance from differentiation to proliferation induced by RHAMM overexpression may link to the pathogenesis of bone neoplasms such as HCF.

Role of receptor for hyaluronic acid-mediated motility (RHAMM) in low molecular weight hyaluronan (LMWHA)-mediated fibrosarcoma cell adhesion

Hyaluronan (HA) modulates key cancer cell functions through interaction with its CD44 and receptor for hyaluronic acid-mediated motility (RHAMM) receptors. HA was recently found to regulate the migration of fibrosarcoma cells in a manner specifically dependent on its size. Here, we investigated the effect of HA/RHAMM signaling on the ability of HT1080 fibrosarcoma cells to adhere onto fibronectin. Low molecular weight HA (LMWHA) significantly increased (p ≤ 0.01) the adhesion capacity of HT1080 cells, which high molecular weight HA inhibited. The ability of HT1080 RHAMM-deficient cells, but not of CD44-deficient ones, to adhere was significantly decreased (p ≤ 0.001) as compared with control cells. Importantly, the effect of LMWHA on HT1080 cell adhesion was completely attenuated in RHAMM-deficient cells. In contrast, adhesion of RHAMM-deficient cells was not sensitive to high molecular weight HA treatment, which identifies RHAMM as a specific conduit of the LMWHA effect. Western blot and real time-PCR analyses indicated that LMWHA significantly increased RHAMM transcript (p ≤ 0.05) and protein isoform levels (53%, 95 kDa; 37%, 73 kDa) in fibrosarcoma cells. Moreover, Western blot analyses showed that LMWHA in a RHAMM-dependent manner enhanced basal and adhesion-dependent ERK1/2 and focal adhesion kinase (FAK) phosphorylation in HT1080 cells. Utilization of a specific ERK1/2 inhibitor completely inhibited (p ≤ 0.001) LMWHA-dependent adhesion, suggesting that ERK1/2 is a downstream effector of LMWHA/RHAMM signaling. Likewise, the utilization of the specific ERK1 inhibitor resulted in a strong down-regulation of FAK activation in HT1080 cells, which identifies ERK1/2 as a FAK upstream activator. In conclusion, our results suggest that RHAMM/HA interaction regulates fibrosarcoma cell adhesion via the activation of FAK and ERK1/2 signaling pathways.

NCI First International Workshop on The Biology, Prevention and Treatment of Relapse after Allogeneic Hematopoietic Cell Transplantation: report from the committee on prevention of relapse following allogeneic cell transplantation for hematologic malignancies

Prevention of relapse after allogeneic hematopoietic stem cell transplantation is the most likely approach to improve survival of patients treated for hematologic malignancies. Herein we review the limits of currently available transplant therapies and the innovative strategies being developed to overcome resistance to therapy or to fill therapeutic modalities not currently available. These novel strategies include nonimmunologic therapies, such as targeted preparative regimens and posttransplant drug therapy, as well as immunologic interventions, including graft engineering, donor lymphocyte infusions, T cell engineering, vaccination, and dendritic cell-based approaches. Several aspects of the biology of the malignant cells as well as the host have been identified that obviate success of even these newer strategies. To maximize the potential for success, we recommend pursuing research to develop additional targeted therapies to be used in the preparative regimen or as maintenance posttransplant, better characterize the T cell and dendritic cells subsets involved in graft-versus-host disease and the graft-versus-leukemia/tumor effect, identify strategies for timing immunologic or nonimmunologic therapies to eliminate the noncycling cancer stem cell, identify more targets for immunotherapies, develop new vaccines that will not be limited by HLA, and develop methods to identify populations at very high risk for relapse to accelerate clinical development and avoid toxicity in patients not at risk for relapse.

Immunotherapy of AML

The applications of chemotherapy for the treatment of AML have been unchanged over the past three decades, with only 30% of patients demonstrating disease-free survival (DFS) [118]. Despite achieving CR following induction chemotherapy, the majority of patients relapse and succumb to their disease [6]. In view of the limitations encountered by cytarabine/anthracycline based regimes, attention has shifted to immunotherapy as a means to treat AML and provide significant long-term DFS. This chapter will discuss the role of the immune system and recent advances in immunotherapy for the treatment of AML, focusing on cellular and non-cellular approaches.

The role of hyaluronic acid in hemopoietic stem cell biology

The adult mammalian hemopoietic system maintains an extraordinarily large, yet well regulated supply of mature blood cells within the circulation throughout life. The system is capable of rapid recovery and compensation following injury, environmental stress or as a result of genetic disease such as the hemoglobinopathies. Despite the vast amount of research conducted there is still an incomplete understanding of hemopoietic regulation. Nevertheless, it is evident from transplantation studies that ongoing blood cell production is absolutely dependent upon hemopoietic stem cells (HSCs). These rare and potent cells have the capacity for extensive proliferation and the ability to differentiate into all blood cell types. An understanding of HSC regulation is fundamental to understanding hemopoiesis. There is now considerable evidence to demonstrate that in vivo, HSCs are located within defined anatomical sites or niches within the bone marrow. Regulation of HSC fate is mediated by both cell-autonomous mechanisms and extrinsic cues resulting from interactions between cells and extracellular components within the niche. This review focuses on the role of hyaluronic acid, a component of the HSC niche and moreover a HSC-associated glycosaminoglycan, in hemopoiesis and specifically HSC regulation. It is now evident that hyaluronic acid not only provides a physical scaffold or support within the marrow to facilitate localization and retention of HSCs to the stem cell niche but moreover, through ligation with its counter-receptors is able to directly affect the cellular functions of HSCs.

Regenerative medicine and developmental biology: the role of the extracellular matrix

The principles and ultimate goals of regenerative medicine and developmental biology involve a complex sequence of events, culminating in the formation of structurally and functionally normal tissues and organs. The molecular composition of the extracellular matrix (ECM) plays a critical role in cellular migration and differentiation events. Mammalian ECM, derived from various tissues and organs, has been used as a biologic scaffold for therapeutic regenerative applications. Hundreds of thousands of human patients have benefited from the use of biologic scaffolds composed of naturally occurring ECM. The mechanisms by which ECM induces constructive remodeling instead of scar tissue formation are only beginning to be understood. This article reviews composition of mammalian ECM, its poorly understood role in developmental biology, and the clinical applications that have resulted from the use of this naturally occurring scaffold.

Expression and role of the hyaluronan receptor RHAMM in inflammation after bleomycin injury

Lung injury is associated with increased concentrations of hyaluronan (hyaluronic acid, HA). HA modifies cell behavior through interaction with cell-associated receptors such as receptor for HA-mediated motility (RHAMM, CD168). Using a function blocking anti-RHAMM antibody (R36), we investigated the expression and role of RHAMM in the inflammatory response to intratracheal bleomycin in rats. Immunostaining showed increased expression of RHAMM in macrophages 4-7 d after injury. Surface biotin labeling of cells isolated by lavage confirmed increased surface expression of a 70-kD RHAMM after lung injury, and in situ hybridization demonstrated increased RHAMM mRNA in macrophages responding to injury. Time-lapse cinemicrography demonstrated a 5-fold increase in motility of alveolar macrophages from bleomycin-treated animals that was completely blocked by R36 in vitro. Further, HA-stimulated macrophage chemotaxis was also inhibited by R36. Daily administration of R36 to injured animals resulted in a 40% decrease in macrophage accumulation 7 d after injury. Further, H&E staining of tissue sections showed that bleomycin-mediated changes in lung architecture were improved with R36 treatment. Taken together with previous results showing the inhibitory effects of HA-binding peptide on inflammation and fibrosis, we conclude that the interaction of RHAMM with HA is a critical component of the recruitment of inflammatory cells to the lung after injury.

Hyaluronic acid facilitates the recovery of hematopoiesis following 5-fluorouracil administration

The fate of hematopoietic stem cells (HSCs) is determined by microenvironmental niches, but the molecular structure of these local networks is not yet completely characterized. Our recent observation that glycosaminoglycan hyaluronic acid (HA), a major component of the bone marrow extracellular matrix, is required for in vitro hematopoiesis led us to suggest a role for HA in structuring the hematopoietic niche. Accordingly, HA deprivation induced by various treatments might lead to an imbalance of normal HSC homeostasis. Since 5-fluorouracil (5-FU) administration sharply decreases the amount of cell surface-associated HA in bone marrow, we examined whether the administration of exogenous HA enhances suppressed hematopoiesis in 5-FU-treated mice. HA administered to mice following 5-FU infusion facilitated the recovery of leukocytes and thrombocytes in the peripheral blood. Intravenously infused HA was found in the bone marrow, where it bound endothelial cells and resident macrophages and increased expression of the hematopoiesis-supportive cytokines interleukin-1 and interleukin-6. In agreement with these observations, enhanced hematopoietic activity was detected in the bone marrow, as measured by elevated counts of long-term culture-initiating cells (LTC-ICs), committed progenitors, and the total number of mature bone marrow cells. Overall, our results suggest that HA is required for regulation of the hematopoiesis-supportive function of bone marrow accessory cells and, therefore, participates in hematopoietic niche assembly.

Xenogeneic extracellular matrix as a scaffold for tissue reconstruction

Bioscaffolds derived from xenogeneic extracellular matrix (ECM) have been used in numerous tissue engineering applications. The safety and efficacy of such scaffolds when used for the repair and reconstruction of numerous body tissues including musculoskeletal, cardiovascular, urogenital and integumentary structures has been shown in both preclinical animal studies and in human clinical studies. More than 200,000 human patients have been implanted with xenogeneic ECM scaffolds. These ECM scaffolds are typically prepared from porcine organs such as small intestine or urinary bladder, which are subjected to decellularization and terminal sterilization without significant loss of the biologic effects of the ECM. The composition of these bioscaffolds includes the structural and functional proteins that are part of native mammalian extracellular matrix. The three-dimensional organization of these molecules distinguishes ECM scaffolds from synthetic scaffold materials and is associated with constructive tissue remodeling instead of scar tissue. The biologic response to these xenogeneic bioscaffolds, including the immune response, is discussed herein.

Hyaluronic acid: its role in voice

The extracellular matrix (ECM), once regarded simply as a structural scaffold, is now recognized as an important modulator of cellular behavior and function. One component that plays a prominent role in this process is hyaluronic acid (HA)--a molecule found in many different tissues. Research into the roles of HA indicates that it plays a key role in tissue viscosity, shock absorption, and space filling. Specifically, research into the role of HA in laryngology indicates that it has profound effects on the structure and viscosity of vocal folds. This article provides an introduction to the structure and biological functions of HA and its importance in voice. In addition, an overview of the pharmaceutical applications of HA is discussed.

The hyaluronan receptor RHAMM/IHABP in astrocytoma cells: expression of a tumor-specific variant and association with microtubules

Hyaluronan binding to its cellular receptors CD44 and ICAM-1 appears to enhance the malignant behavior of tumors, including astrocytomas. RHAMM/IHABP, another hyaluronan receptor, has been identified in breast carcinoma cells, but its presence in astrocytomas is yet undetermined. Herein, we report that a monoclonal antibody against plectin (a cytoskeletal protein linker) recognizes on Western blots of U-373 MG glioblastoma cells, a 300-kDa band corresponding to plectin and two bands of 86 and 70 kDa. cDNA cloning and Northern blotting reveals that these two bands represent isoforms of RHAMM/IHABP. Sequence comparisons suggest that the plectin monoclonal antibody recognizes RHAMM/IHABP because this protein and plectin share short peptide sequences of similar primary and secondary structure. Western blotting demonstrates that most human astrocytoma tissues and cell lines express the 86- and 70-kDa isoforms of RHAMM/IHABP. Interestingly, the 70-kDa variant is undetectable in normal brain tissues and in primary cultures of astrocytes suggesting that its expression is tumor-specific. Transfection experiments with epitope-tagged RHAMM/IHABP cDNA established that RHAMM/IHABP associates with microtubules in astrocytoma cells, while in normal astrocytes it either co-localizes with microtubules or has a diffuse cytoplasmic distribution. This suggests that RHAMM/IHABP has the capacity to bind to microtubules in normal and transformed astrocytes, and that neoplasia may favor this association.

Peptides that mimic glycosaminoglycans: high-affinity ligands for a hyaluronan binding domain

BACKGROUND

Hyaluronan (HA) is a non-sulfated glycosaminoglycan (GAG) that promotes motility, adhesion, and proliferation in mammalian cells, as mediated by cell-surface HA receptors. We sought to identify non-carbohydrate ligands that would bind to and activate cell-surface HA receptors. Such analogs could have important therapeutic uses in the treatment of cancer, wound healing, and arthritis, since such ligands would be resistant to degradation by hyaluronidase (HAse).

RESULTS

Peptide ligands that bind specifically to the recombinant HA binding domain (BD) of the receptor for hyaluronan-mediated motility (RHAMM) were obtained by screening two peptide libraries: (i) random 8-mers and (ii) biased 8-mers with alternating acidic side chains, i.e. XZXZXZXZ (X=all-L-amino acids except Cys, Lys, or Arg; Z=D-Asp, L-Asp, D-Glu, or L-Glu). Selectivity of the peptide ligands for the HABD was established by (i) detection of binding of biotin- or fluorescein-labeled peptides to immobilized proteins and (ii) fluorescence polarization of FITC-labeled peptides with the HABD in solution. HA competitively displaced binding of peptides to the HABD, while other GAGs were less effective competitors. The stereochemistry of four biased octapeptides was established by synthesis of the 16 stereoisomers of each peptide. Binding assays demonstrated a strong preference for alternating D and L configurations for the acidic residues, consistent with the calculated orientation of glucuronic acid moieties of HA.

CONCLUSIONS

Two classes of HAse-resistant peptide mimetics of HA were identified with high affinity, HA-compatible binding to the RHAMM HABD. This demonstrated that non-HA ligands specific to a given HA binding protein could be engineered, permitting receptor-specific targeting.

Identification of sequence, protein isoforms, and distribution of the hyaluronan-binding protein RHAMM in adult and developing rat brain

The protein RHAMM (for "receptor for hyaluronan-mediated motility"; CD168) is a member of the hyaladherin family of hyaluronan-binding proteins. RHAMM has a role in cell signaling, migration, and adhesion via interactions with hyaluronan, microtubules, actin, calmodulin, and components of the extracellular regulated kinase (erk) signaling pathway. Based on previous findings of potentially similar roles in neural cells in culture, we investigated the molecular characteristics, protein expression profile, and distribution of RHAMM in rat brain. Reverse transcriptase-polymerase chain reaction (RT-PCR) using RNA isolated from adult rat brain yielded a single RHAMM sequence of 2.1 kilobases encoding a protein of 82.4 kDa. RHAMM is subject to alternate splicing in other systems, but no RT-PCR evidence was found for splice variants in brain, although our analysis does not rule out this possibility. The amino acid sequence displayed homology with human and murine RHAMM (74% and 80%, respectively) but contained only one copy of a 21-amino-acid sequence that is repeated five times in the murine homologue. By using anti-RHAMM antibodies, several RHAMM isoforms were identified in brain. Immunohistochemically, RHAMM was found in the vast majority of neurons and in many oligodendrocytes throughout brain, with heterogeneous levels among cell populations, and was confined to the somata and initial processes of these cells. RHAMM was detected in neurons of cerebral cortex and most subcortical and brainstem structures at postnatal day 1 and exhibited an adult distribution pattern by postnatal day 5. High levels were detected in oligodendrocytes by postnatal day 10. The widespread expression of RHAMM in adult and developing brain implies a role for this protein and its ligand hyaluronan in key events of cell signaling and cytoskeletal regulation in the CNS.

Subcellular distribution, calmodulin interaction, and mitochondrial association of the hyaluronan-binding protein RHAMM in rat brain

The CNS contains high levels of the glycosaminoglycan hyaluronan, and neural cells express a variety of proteins that are members of the hyaladherin family of hyaluronan-binding proteins. We have previously shown that the hyaladherin RHAMM (receptor for hyaluronan-mediated motility; CD168) is expressed by neural cells in culture; plays a role in astrocyte motility, neurite migration, and axonal growth; and is widely distributed in neurons and oligodendrocytes of developing and adult rat CNS. Here we demonstrate differential localization of various forms of RHAMM in subcellular fractions of adult rat brain. Western blotting indicated the presence of 66, 75, and 85-90 kDa molecular weight RHAMM forms in whole-brain homogenates. Subfractionation revealed enrichment of the 66 and 85-90 kDa forms in soluble fractions, whereas the 75 kDa form was enriched in mitochondrial fractions. This latter form was retained in osmotically shocked mitochondria, but was liberated by alkali carbonate, suggesting a nonintrinsic mitochondrial membrane association. By double immunohistochemical labeling for RHAMM and the mitochondrial marker cytochrome oxidase, RHAMM was localized to isolated mitochondria in vitro and to neuronal mitochondria in vivo. Hyaluronan-sepharose chromatography and cetylpiridinium chloride precipitation confirmed the hyaluronan-binding capacity of RHAMM forms. By calmodulin-affinity chromatography, endogenously expressed brain RHAMM was demonstrated to bind calmodulin in a Ca2+-dependent manner. These results, together with reports of RHAMM association with actin and microtubules in other systems, suggest a role of RHAMM in calmodulin-mediated cell signaling to cytoskeletal elements and/or mitochondria in the CNS and invoke novel functions of its interactions with hyaluronan.

Sequence, protein expression and extracellular-regulated kinase association of the hyaladherin RHAMM (receptor for hyaluronan mediated motility) in PC12 cells

Differentiation of PC12 cells by nerve growth factor (NGF) or fibroblast growth factor-2 (FGF2) is dependent on signaling mediated by extracellular regulated kinase (ERK). We investigated the involvement of receptor for hyaluronan mediated motility (RHAMM) in this signaling pathway. A single RHAMM 3.2 kb transcript was detected in PC12 RNA. Reverse transcriptase-polymerase chain reaction generated a 2141 bp cDNA that had identical sequence to rat brain RHAMM and showed no evidence of alternate splicing. Several RHAMM species were identified by Western blotting. Immunohistochemistry showed RHAMM localization to the cytoskeleton, neurites and growth cones. Following stimulation of PC12 cells with NGF or FGF2 RHAMM was co-immunoprecipitated by phosphorylation-specific anti-ERK antibodies, indicating a role for RHAMM in ERK signaling in PC12 cells.

Hyaluronate receptors mediating glioma cell migration and proliferation

The extracellular matrix (ECM) of the central nervous system (CNS) is enriched in hyaluronate (HA). Ubiquitous receptors for HA are CD44 and the Receptor for HA-Mediated Motility known as RHAMM. In the present study, we have investigated the potential role of CD44 and RHAMM in the migration and proliferation of human astrocytoma cells. HA-receptor expression in brain tumor cell lines and surgical specimens was determined by immunocytochemistry and western blot analyses. The ability of RHAMM to bind ligand was determined through cetylpyridinium chloride (CPC) precipitations of brain tumor lysates in HA-binding assays. The effects of HA, CD44 blocking antibodies, and RHAMM soluble peptide on astrocytoma cell growth and migration was determined using MTT and migration assays. Our results show that the expression of the HA-receptors, CD44, and RHAMM, is virtually ubiquitous amongst glioma cell lines, and glioma tumor specimens. There was a gradient of expression amongst gliomas with high grade gliomas expressing more RHAMM and CD44 than did lower grade lesions or did normal human astrocytes or non-neoplastic specimens of human brain. Specific RHAMM variants of 85- and 58-kDa size were shown to bind avidly to HA following CPC precipitations. RHAMM soluble peptide inhibited glioma cell line proliferation in a dose-dependent fashion. Finally, while anti-CD44 antibodies did not inhibit the migration of human glioma cells, soluble peptides directed at the HA-binding domain of RHAMM inhibited glioma migration both on and off an HA-based ECM. These data support the notion that HA-receptors contribute to brain tumor adhesion, proliferation, and migration, biological features which must be better understood before more effective treatment strategies for these tumors can be found.

Tracking the invasiveness of human astrocytoma cells by using green fluorescent protein in an organotypical brain slice model

OBJECT

Although it is known that malignant astrocytomas infiltrate diffusely into regions of normal brain, it is frequently difficult to identify unequivocally the solitary, invading astrocytoma cell in histopathological preparations or experimental astrocytoma models. The authors describe an experimental system that facilitates the tracking of astrocytoma cells by using nonneoplastic cerebral tissue as the substrate for invasion.

METHODS

Cerebral tissue was cut into 1-mm-thick slices and cultured in the upper chamber of a Transwell culture dish on top of a polyester membrane (0.4-mm pore size) that was bathed in medium supplied by the lower chamber. Two astrocytoma cell lines, U-87 MG (U87) and U343 MG-A (U343), were selected because of their differing basal cell motilities in monolayer cultures. The astrocytoma cells were stably transfected with vectors that expressed green fluorescent protein (GFP), either alone or as a fusion protein with the receptor for hyaluronic acid-mediated motility (RHAMM) in either sense or antisense orientations. Stably transfected clones that had high levels of GFP expression were selected using the direct visualization provided by fluorescence microscopy and fluorescence-activated cell-sorter analysis. The GFP-expressing astrocytoma cell clones were implanted into the center of the brain slice and the degree of astrocytoma invasion into brain tissue was measured at different time points by using the optical sectioning provided by the confocal laser microscope. The authors observed that GFP-expressing astrocytoma cells could be readily tracked and followed in this model system. Individual astrocytoma cells that exhibited green fluorescence could be readily identified following their migration through the brain slices. The GFP-labeled U87 astrocytoma cells migrated farther into the brain slice than the U343 astrocytoma cells. The RHAMM-transfected GFP-labeled astrocytoma cells also infiltrated farther than the GFP-labeled astrocytoma cells themselves. The expression of antisense RHAMM virtually abrogated the invasion of the brain slices by both astrocytoma cell lines.

CONCLUSIONS

The authors believe that this organotypical culture system may be of considerable utility in studying the process of astrocytoma invasion, not only because it provides a better representation of the extracellular matrix molecules normally encountered by invading astrocytoma cells, but also because the GFP tag enables tracking of highly migratory and invasive astrocytoma cells under direct vision.

Differences in hyaluronic acid-mediated functions and signaling in arterial, microvessel, and vein-derived human endothelial cells

Hyaluronic acid (HA), a nonsulfated glycosaminoglycan, regulates cell adhesion and migration. Small HA fragments (3-25 disaccharide units) induce neovascularization. We investigated the effect of HA and a HA fragment (10-15 disaccharide units, F1) on primary human endothelial cells (ECs). Human pulmonary ECs (HPAEC) and lung microvessel ECs (HMVEC-L) bound HA (K(d) approximately 1 and 2.3 nm, respectively) and expressed 17,780 and 16,690 HA binding sites, respectively. Both ECs showed HA-mediated cell adhesion; however, HMVEC-L was 1.5-fold better. Human umbilical vein ECs neither bound HA nor showed HA-mediated adhesion. All three ECs expressed CD44 ( approximately 110 kDa). The expression of receptor for HA-mediated motility (RHAMM) (approximately 80 kDa) was the highest in HMVEC-L, followed by HPAEC and human umbilical vein ECs. RHAMM, not CD44, bound HA in all three ECs. F1 was better than HA and stimulated a 2. 5- and 1.8-fold mitogenic response in HMVEC-L and HPAEC, respectively. Both HA and F1 induced tyrosine phosphorylation of p125(FAK), paxillin, and p42/44 ERK in HMVEC-L and HPAEC, which was blocked by an anti-RHAMM antibody. These results demonstrate that RHAMM is the functional HA receptor in primary human ECs. Heterogeneity exists among primary human ECs of different vascular origins, with respect to functional HA receptor expression and function.

The intracellular hyaluronan receptor RHAMM/IHABP interacts with microtubules and actin filaments

We reported recently on the intracellular localisation of the hyaluronan receptor RHAMM/IHABP in human cancer cells. Here we describe the colocalisation of RHAMM/IHABP proteins with microtubules, both in interphase and dividing cells, suggesting that RHAMM/IHABP represents a novel member of the family of microtubule-associated proteins (MAPs). We have identified four different splice variants of RHAMM/IHABP, all of which colocalise, at least transiently, with microtubules when expressed as GFP fusion proteins in HeLa cells. Using microtubule-binding assays and transient transfection experiments of deletion-bearing RHAMM/IHABP mutants, we localised the microtubule-binding region to the extreme N terminus of RHAMM/IHABP. This interaction domain is composed of two distinct subdomains, one of which is sufficient to mediate binding to the mitotic spindle while both domains are required for binding of RHAMM/IHABP proteins to interphase microtubules. Sequence analysis revealed that the projection domain of RHAMM/IHABP is predicted to form coiled-coils, implying that RHAMM/IHABP represents a filamentous protein capable of interacting with other proteins and we found that RHAMM/IHABP interacts with actin filaments in vivo and in vitro. Moreover, in vitro translated RHAMM/IHABP isoforms efficiently bind to immobilised calmodulin in a Ca(2+)-dependent manner via a calmodulin-binding site within the projection domain of RHAMM/IHABP (residues 574–602). Taken together, our results strongly suggest that RHAMM/IHABP is a ubiquitously expressed, filamentous protein capable of interacting with microtubules and microfilaments and not, as numerous previous reports suggest, a cell surface receptor for the extracellular matrix component hyaluronan.

Potential Role for Hyaluronan and the Hyaluronan Receptor RHAMM in Mobilization and Trafficking of Hematopoietic Progenitor Cells

Although the mechanism(s) underlying mobilization of hematopoietic progenitor cells (HPCs) is unknown, detachment from the bone marrow (BM) microenvironment and motility are likely to play a role. This work analyzes the motile behavior of HPCs and the receptors involved. CD34+45lo/medScatterlo/med HPCs from granulocyte colony-stimulating factor (G-CSF)–mobilized blood and mobilized BM were compared with steady-state BM for their ability to bind hyaluronan (HA), their expression of the HA receptors RHAMM and CD44, and their motogenic behavior. Although RHAMM and CD44 are expressed by mobilized blood HPCs, function blocking monoclonal antibodies (MoAbs) identified RHAMM as a major HA binding receptor, with a less consistent participation by CD44. Permeabilization of mobilized blood HPCs showed a pool of intracellular (ic) RHAMM and a smaller pool of icCD44. In contrast, steady-state BM HPCs have significantly larger pools of icRHAMM and icCD44. Also, in contrast to mobilized blood HPCs, for steady-state BM HPCs, MoAbs to RHAMM and CD44 act as agonists to upregulate HA binding. The comparison between mobilized and steady-state BM HPCs suggests that G-CSF mobilization is associated with depletion of intracellular stores of HA receptors and modulates HA receptor usage. To confirm that mobilization alters the HA receptor distribution and usage by HPCs, samples of BM were collected at the peak of G-CSF mobilization in parallel with mobilized blood samples. HA receptor distribution of mobilized BM HPCs was closely matched with mobilized blood HPCs and different from steady-state BM HPCs. Mobilized BM HPCs had lower pools of icHA receptors, similar to those of mobilized blood HPCs. Treatment of mobilized BM HPCs with anti-RHAMM MoAb decreased HA binding, in contrast to steady-state BM HPCs. Thus, G-CSF mobilization may stimulate an autocrine stimulatory loop for HPCs in which HA interacts with basal levels of RHAMM and/or CD44 to stimulate receptor recycling. Consistent with this, treatment of HPCs with azide, nystatin, or cytochalasin B increased HA binding, implicating an energy-dependent process involving lipid rafts and the cytoskeleton. Of the sorted HPCs, 66% were adherent and 27% were motile on fibronectin plus HA. HPC adherence was inhibited by MoAbs to β1 integrin and CD44, but not to RHAMM, whereas HPC motility was inhibited by MoAb to RHAMM and β1 integrin, but not to CD44. This finding suggests that RHAMM and CD44 play reciprocal roles in adhesion and motility by HPCs. The G-CSF–associated alterations in RHAMM distribution and the RHAMM-dependent motility of HPCs suggest a potential role for HA and RHAMM in trafficking of HPCs and the possible use of HA as a mobilizing agent in vivo.

Potential Role for Hyaluronan and the Hyaluronan Receptor RHAMM in Mobilization and Trafficking of Hematopoietic Progenitor Cells

Although the mechanism(s) underlying mobilization of hematopoietic progenitor cells (HPCs) is unknown, detachment from the bone marrow (BM) microenvironment and motility are likely to play a role. This work analyzes the motile behavior of HPCs and the receptors involved. CD34+45lo/medScatterlo/med HPCs from granulocyte colony-stimulating factor (G-CSF)–mobilized blood and mobilized BM were compared with steady-state BM for their ability to bind hyaluronan (HA), their expression of the HA receptors RHAMM and CD44, and their motogenic behavior. Although RHAMM and CD44 are expressed by mobilized blood HPCs, function blocking monoclonal antibodies (MoAbs) identified RHAMM as a major HA binding receptor, with a less consistent participation by CD44. Permeabilization of mobilized blood HPCs showed a pool of intracellular (ic) RHAMM and a smaller pool of icCD44. In contrast, steady-state BM HPCs have significantly larger pools of icRHAMM and icCD44. Also, in contrast to mobilized blood HPCs, for steady-state BM HPCs, MoAbs to RHAMM and CD44 act as agonists to upregulate HA binding. The comparison between mobilized and steady-state BM HPCs suggests that G-CSF mobilization is associated with depletion of intracellular stores of HA receptors and modulates HA receptor usage. To confirm that mobilization alters the HA receptor distribution and usage by HPCs, samples of BM were collected at the peak of G-CSF mobilization in parallel with mobilized blood samples. HA receptor distribution of mobilized BM HPCs was closely matched with mobilized blood HPCs and different from steady-state BM HPCs. Mobilized BM HPCs had lower pools of icHA receptors, similar to those of mobilized blood HPCs. Treatment of mobilized BM HPCs with anti-RHAMM MoAb decreased HA binding, in contrast to steady-state BM HPCs. Thus, G-CSF mobilization may stimulate an autocrine stimulatory loop for HPCs in which HA interacts with basal levels of RHAMM and/or CD44 to stimulate receptor recycling. Consistent with this, treatment of HPCs with azide, nystatin, or cytochalasin B increased HA binding, implicating an energy-dependent process involving lipid rafts and the cytoskeleton. Of the sorted HPCs, 66% were adherent and 27% were motile on fibronectin plus HA. HPC adherence was inhibited by MoAbs to β1 integrin and CD44, but not to RHAMM, whereas HPC motility was inhibited by MoAb to RHAMM and β1 integrin, but not to CD44. This finding suggests that RHAMM and CD44 play reciprocal roles in adhesion and motility by HPCs. The G-CSF–associated alterations in RHAMM distribution and the RHAMM-dependent motility of HPCs suggest a potential role for HA and RHAMM in trafficking of HPCs and the possible use of HA as a mobilizing agent in vivo.

Overexpression of the Receptor for Hyaluronan-Mediated Motility (RHAMM) Characterizes the Malignant Clone in Multiple Myeloma: Identification of Three Distinct RHAMM Variants

The receptor for hyaluronan (HA)-mediated motility (RHAMM) controls motility by malignant cells in myeloma and is abnormally expressed on the surface of most malignant B and plasma cells in blood or bone marrow (BM) of patients with multiple myeloma (MM). RHAMM cDNA was cloned and sequenced from the malignant B and plasma cells comprising the myeloma B lineage hierarchy. Three distinct RHAMM gene products, RHAMMFL, RHAMM−48, and RHAMM−147, were cloned from MM B and plasma cells. RHAMMFL was 99% homologous to the published sequence of RHAMM. RHAMM−48 and RHAMM−147 variants align with RHAMMFL, but are characterized by sequence deletions of 48 bp (16 amino acids [aa]) and 147 bp (49 aa), respectively. The relative frequency of these RHAMM transcripts in MM plasma cells was determined by cloning of reverse-transcriptase polymerase chain reaction (RT-PCR) products amplified from MM plasma cells. Of 115 randomly picked clones, 49% were RHAMMFL, 47% were RHAMM−48, and 4% were RHAMM−147. All of the detected RHAMM variants contain exon 4, which is alternatively spliced in murine RHAMM, and had only a single copy of the exon 8 repeat sequence detected in murine RHAMM. RT-PCR analysis of sorted blood or BM cells from 22 MM patients showed that overexpression of RHAMM variants is characteristic of MM B cells and BM plasma cells in all patients tested. RHAMM also appeared to be overexpressed in B lymphoma and B-chronic lymphocytic leukemia (CLL) cells. In B cells from normal donors, RHAMMFL was only weakly detectable in resting B cells from five of eight normal donors or in chronically activated B cells from three patients with Crohn’s disease. RHAMM−48 was detectable in B cells from one of eight normal donors, but was undetectable in B cells of three donors with Crohn’s disease. RHAMM−147 was undetectable in normal and Crohn’s disease B cells. In situ RT-PCR was used to determine the number of individual cells with aggregate RHAMM transcripts. For six patients, 29% of BM plasma cells and 12% of MM B cells had detectable RHAMM transcripts, while for five normal donors, only 1.2% of B cells expressed RHAMM transcripts. This work suggests that RHAMMFL, RHAMM−48, and RHAMM−147 splice variants are overexpressed in MM and other B lymphocyte malignancies relative to resting or in vivo–activated B cells, raising the possibility that RHAMM and its variants may contribute to the malignant process in B-cell malignancies such as lymphoma, CLL, and MM.

Overexpression of the Receptor for Hyaluronan-Mediated Motility (RHAMM) Characterizes the Malignant Clone in Multiple Myeloma: Identification of Three Distinct RHAMM Variants

The receptor for hyaluronan (HA)-mediated motility (RHAMM) controls motility by malignant cells in myeloma and is abnormally expressed on the surface of most malignant B and plasma cells in blood or bone marrow (BM) of patients with multiple myeloma (MM). RHAMM cDNA was cloned and sequenced from the malignant B and plasma cells comprising the myeloma B lineage hierarchy. Three distinct RHAMM gene products, RHAMMFL, RHAMM−48, and RHAMM−147, were cloned from MM B and plasma cells. RHAMMFL was 99% homologous to the published sequence of RHAMM. RHAMM−48 and RHAMM−147 variants align with RHAMMFL, but are characterized by sequence deletions of 48 bp (16 amino acids [aa]) and 147 bp (49 aa), respectively. The relative frequency of these RHAMM transcripts in MM plasma cells was determined by cloning of reverse-transcriptase polymerase chain reaction (RT-PCR) products amplified from MM plasma cells. Of 115 randomly picked clones, 49% were RHAMMFL, 47% were RHAMM−48, and 4% were RHAMM−147. All of the detected RHAMM variants contain exon 4, which is alternatively spliced in murine RHAMM, and had only a single copy of the exon 8 repeat sequence detected in murine RHAMM. RT-PCR analysis of sorted blood or BM cells from 22 MM patients showed that overexpression of RHAMM variants is characteristic of MM B cells and BM plasma cells in all patients tested. RHAMM also appeared to be overexpressed in B lymphoma and B-chronic lymphocytic leukemia (CLL) cells. In B cells from normal donors, RHAMMFL was only weakly detectable in resting B cells from five of eight normal donors or in chronically activated B cells from three patients with Crohn’s disease. RHAMM−48 was detectable in B cells from one of eight normal donors, but was undetectable in B cells of three donors with Crohn’s disease. RHAMM−147 was undetectable in normal and Crohn’s disease B cells. In situ RT-PCR was used to determine the number of individual cells with aggregate RHAMM transcripts. For six patients, 29% of BM plasma cells and 12% of MM B cells had detectable RHAMM transcripts, while for five normal donors, only 1.2% of B cells expressed RHAMM transcripts. This work suggests that RHAMMFL, RHAMM−48, and RHAMM−147 splice variants are overexpressed in MM and other B lymphocyte malignancies relative to resting or in vivo–activated B cells, raising the possibility that RHAMM and its variants may contribute to the malignant process in B-cell malignancies such as lymphoma, CLL, and MM.

Characterisation of the murine gene encoding the intracellular hyaluronan receptor IHABP (RHAMM)

We have recently shown that the published cDNA sequence encoding the murine cell surface receptor for hyaluronan-mediated motility (RHAMM) in fact represents a partial sequence of the cDNA encoding a new intracellular hyaluronic acid binding protein (IHABP). Here we publish the genomic organisation, including 700bp sequences of the promoter region, of the IHABP gene. The IHABP gene consists of 18 exons and spans more than 25kb. Part of the IHABP gene is identical with the published data on RHAMM. The IHABP gene apparently possesses one promoter region with one major transcriptional start point. IHABP is ubiquitously expressed at the mRNA and the protein level in all murine tissues, suggesting that the function of this intracellular hyaluronan binding protein is not restricted to migrating cells.

The hyaluronan receptor RHAMM in noradrenergic fibers contributes to axon growth capacity of locus coeruleus neurons in an intraocular transplant model

The hyaluronan receptor for hyaluronic acid-mediated motility (RHAMM) plays a role in cell migration and motility in many systems. Recent observations on the involvement of RHAMM in neurite motility in vitro suggest that it might also be important in axon outgrowth in situ. This was addressed directly by investigating both RHAMM expression in the rat CNS and the ability of anti-RHAMM reagents to interfere with tissue growth and axon outgrowth in intraocular brainstem transplants. By western blotting, anti-RHAMM antibody detected a RHAMM isoform of 75,000 mol. wt in both whole brain homogenate and synaptosome preparations, and a 65,000 mol. wt isoform in synaptosomes. Immunofluorescence of adult brain sections revealed RHAMM-like immunoreactivity in varicose fibers that were also positive for the noradrenergic marker dopamine-beta-hydroxylase. Not all noradrenergic fibers contained RHAMM, nor was RHAMM detected in other monoaminergic fiber types. Lesions of noradrenergic fiber systems with beta-halobenzylamine-N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) eliminated RHAMM-positive fibers, but noradrenergic axons that sprouted extensively after this treatment were strongly RHAMM-positive. To assess RHAMM's role in fiber outgrowth, fetal brainstem tissue containing noradrenergic neurons was grafted into the anterior chamber of the eye. Treatment of grafts with anti-RHAMM antibody caused significant inhibition of tissue growth and axon outgrowth, as did a peptide corresponding to a hyaluronan binding domain of RHAMM. These agents had no such effects on transplants containing serotonergic and dopaminergic neurons. These results suggest that RHAMM, an extracellular matrix receptor previously shown to contribute to migratory and contact behavior of cells, may also be important in the growth and/or regenerative capacity of central noradrenergic fibers originating from the locus coeruleus.

The human hyaluronan receptor RHAMM is expressed as an intracellular protein in breast cancer cells

The receptor for hyaluronan mediated motility (RHAMM) has been reported to mediate migration, transformation, and metastatic spread of murine fibroblasts. Here we describe the expression of two human RHAMM isoforms, which are generated by alternative splicing of the primary gene transcript, by a series of human breast carcinoma cell lines. A polyclonal antibody, raised against a bacterially expressed RHAMM fusion protein, detected an 85–90 kDa protein by western blot analysis. No correlation between the level of RHAMM mRNA and protein expression with known metastatic/malignant potential of the tumour cell lines was observed. Interestingly, we found that the antibody did not stain the cell surface but the cytoplasm of breast cancer cells. The intracellular localisation of RHAMM was confirmed by subcellular fractionation studies. RHAMM proteins were capable of binding to hyaluronan, but not to heparin or chondroitin sulphate, in an vitro binding assay. We also provide evidence that a potential hyaluronan-binding motif in the N terminus of the protein is not involved in the interaction of RHAMM with hyaluronan. Our findings lead us to conclude that RHAMM does not function as a conventional motility receptor for HA in human breast cancer cells and we suggest the term RHAMM be substituted by ‘intracellular hyaluronic acid binding protein’ (IHABP).

Identification of IHABP, a 95 kDa intracellular hyaluronate binding protein

The extracellular matrix component hyaluronan is believed to play important roles in various processes of organogenesis, cell migration and cancer. Recognition of and binding to hyaluronan is mediated by cell surface receptors. Three of them, CD44, ICAM-1 and RHAMM (receptor for hyaluronic acid mediated motility), have been identified. A cDNA clone designated RHAMM turned out to possess transforming capacity. Based on this published sequence, we isolated the complete cDNA of the murine gene. The cDNA comprises an open reading frame of 2.3 kb and encodes a 95 kDa protein. The protein carries a hyaluronan binding motif which binds to hyaluronan in vitro but not to heparin or chondroitin sulphate. It is ubiquitously expressed in normal cells and in all tumour cell lines irrespective of their metastatic properties. One tumour cell line, the metastatic Lewis lung carcinoma, expresses a larger 105 kDa variant form of the protein due to a genomic rearrangement. Antibodies raised against the 95 kDa protein were used for subcellular localization studies. The hyaluronan binding protein is not detectable at the cell surface but is rather localized exclusively intracellularly. Clearly, the sequence we have identified encodes a protein with properties substantially different to the RHAMM protein. We tentatively name the protein intracellular hyaluronic acid binding protein, IHABP.

The hyaluronan receptor RHAMM regulates extracellular-regulated kinase

We have identified two RHAMM (receptor for hyaluronan-mediated motility) isoforms that encode an alternatively spliced exon 4 (Hall, C. L., Yang, B., Yang, X., Zhang, S., Turley, M., Samuel, S., Lange, L. A., Wang, C., Curpen, G. D., Savani, R. C., Greenberg, A. H., and Turley, E. A. (1995) Cell 82, 19-26 and Wang, C., Entwistle, J., Hou, G., Li, Q., and Turley, E. A. (1996) Gene 174, 299-306). One of these, RHAMM variant 4 (RHAMMv4), is transforming when overexpressed and regulates Ras signaling (Hall et al.). Here we note using flow cytometry and confocal analysis that RHAMM isoforms encoding exon 4 occur both on the cell surface and in the cytoplasm. Epitope-tagging experiments indicate that RHAMMv4 occurs only in the cytoplasm. Several observations suggest that both cell surface RHAMM isoforms and RHAMMv4 are involved in regulating extracellular-regulated kinase (ERK) activity. Affinity-purified anti-RHAMM exon 4 antibodies block the ability of platelet-derived growth factor to activate ERK, and these reagents modify the protein tyrosine phosphorylation profile of proteins resulting from treatment with platelet-derived growth factor. A dominant negative form of RHAMMv4 inhibits mutant active Ras activation of ERK and coimmunoprecipitates with both mitogen-activated protein kinase kinase and ERK, suggesting that the intracellular RHAMMv4 acts downstream of Ras, possibly at the level of mitogen-activated protein kinase kinase-ERK interactions. Consistent with this, overexpression of RHAMMv4 constitutively activates ERK. These results identify a novel mechanism for the regulation of the Ras-ERK signaling pathway and suggest that RHAMM plays multiple roles in this regulation.

The characterization of a human RHAMM cDNA: conservation of the hyaluronan-binding domains

A full-length human RHAMM cDNA clone was isolated by a combination of screening a human breast cDNA expression library with the murine RHAMM 2 cDNA as well as 5' RACE and RT-PCR using messenger RNA from human breast cell line (MCF-10A). The full-length cDNA contained 725 aa that encoded an 84 kDa protein. Although the coding region of the human RHAMM cDNA resembles the murine RHAMM v4, it has additional unique N-terminal (489 bp) and C-terminal (33 bp) regions. Also, only 1 of 5 repeat sequences encoded in the murine cDNA are present in human cDNA. The overall homology between the overlapping region of human and mouse RHAMM v4 cDNA clone is 85%, but the HA binding motif (B[X7]B), shown to be critical for the signaling capability of this receptor, is 100% conserved.

HA receptors: regulators of signalling to the cytoskeleton

Hyaluronan (HA) is a ubiquitous component of the extracellular matrix (ECM) and occurs transiently in both the cell nucleus and cytoplasm. It has been shown to promote cell motility, adhesion, and proliferation and thus it has an important role in such processes as morphogenesis, wound repair, inflammation, and metastasis. These processes require massive cell movement and tissue reorganization and are always accompanied by elevated levels of HA. Many of the effects of HA are mediated through cell surface receptors, three of which have been molecularly characterized, namely CD44, RHAMM, and ICAM-1. Binding of the HA ligand to its receptors triggers signal transduction events which, in concert with other ECM and cytoskeletal components, can direct cell trafficking during physiological and pathological events. The HA mediated signals are transmitted, at least in part, by the activation of protein phosphorylation cascades, cytokine release, and the stimulation of cell cycle proteins. A variety of extracellular signals regulate the expression of both HA and the receptors necessitating that HA-receptor signalling is a tightly controlled process. Regulated production of soluble forms of the receptors, alternately spliced cell surface isoforms, and glycosylation variants of these receptors can dramatically modulate HA binding, ligand specificity, and stimulation of the signalling pathway. When these processes are deregulated cell behaviour becomes uncontrolled leading to developmental abnormalities, abnormal physiological responses, and tumorigenesis. The elucidation of the molecular mechanisms regulating HA-mediated events will not only contribute greatly to our understanding of a variety of disease processes but will also offer many new avenues of therapeutic intervention.

Overexpression of the hyaluronan receptor RHAMM is transforming and is also required for H-ras transformation

Overexpression of the RHAMM gene by transfection into fibroblasts is transforming and causes spontaneous metastases in the lung. H-ras-transformed fibrosarcomas transfected with a dominant suppressor mutant of RHAMM exhibit a so-called revertant phenotype and are completely nontumorigenic and nonmetastatic. Conversely, fibroblasts stably expressing low levels of RHAMM as a result of antisense transfection are resistant to ras transformation. Collectively, these results indicate that RHAMM acts downstream of ras. The loss of functional RHAMM ablates signaling within focal adhesions, in particular changes in focal adhesion kinase phosphorylation, and as a result these focal adhesions are unable to turn over in response to hyaluronan. These results provide evidence of the oncogenic potential of a novel extracellular matrix receptor and establish a functional link between transformation by ras and signaling within focal adhesions that are required for transformation by this oncogene.