Purification of a hyaluronate-binding protein fraction that modifies cell social behavior

miR-9-5p/HMMR regulates the tumorigenesis and progression of clear cell renal cell carcinoma through EMT and JAK1/STAT1 signaling pathway

BACKGROUND

The most common malignant type of kidney cancer is clear cell renal cell carcinoma (ccRCC). The expression levels of hyaluronan-mediated motility receptor (HMMR) in many tumor types are significantly elevated. HMMR is closely associated with tumor-related progression, treatment resistance, and poor prognosis, and has yet to be fully investigated in terms of its expression patterns and molecular mechanisms of action in ccRCC. Further research is imperative to elucidate these aspects.

METHODS

We used The Cancer Genome Atlas (TCGA) database to preliminarily investigate HMMR expression and function in ccRCC and the data for 19 samples from the NCBI GEO database (GSE207493) for single-cell analysis. We assessed the differential expression level of HMMR between ccRCC cancerous tissues and their matched non-tumor tissues. Subsequently, a series of in vivo and in vitro experiments were designed to elucidate the biological function of HMMR in ccRCC, including Transwell assays, CCK-8 assays, clone formation assays and subcutaneous xenograft experiments in nude mice. Through bioinformatics analysis, we identified potential microRNAs (miRNAs) that may regulate HMMR, as well as the possible signaling pathways involved. Finally, we conducted a series of cellular functional experiments to validate our hypotheses regarding the HMMR axis.

RESULTS

HMMR expression was significantly up-regulated in tumor tissues of ccRCC patients, and elevated HMMR expression level showed a strong correlation with ccRCC progression and adverse prognoses of patients. Knocking down HMMR inhibited the proliferative and migratory abilities of ccRCC cells, while its overexpression amplified these oncogenic properties. In nude mice model, reduced HMMR expression inhibited ccRCC tumor proliferation in vivo. Furthermore, overexpression of an upstream transcriptional regulator, miR-9-5p, effectively downregulated HMMR expression and thus impeded ccRCC cells proliferation and migration. HMMR might influence ccRCC growth via the Epithelial-Mesenchymal Transition (EMT) pathway and the Janus Kinase 1/Signal Transducer and Activator of Transcription 1 (JAK1/STAT1) pathway.

CONCLUSIONS

HMMR is overexpressed in ccRCC, and there is a significant link between high HMMR expression and tumor progression, as well as poor patient prognosis. Specifically, HMMR could be targeted and inhibited by miR-9-5p and might modulate the tumorigenesis and progression of ccRCC through both EMT and JAK1/STAT1 signaling pathway.

Mechanobiology of Hyaluronan: Connecting Biomechanics and Bioactivity in Musculoskeletal Tissues

Hyaluronan (HA) plays well-recognized mechanical and biological roles in articular cartilage and synovial fluid, where it contributes to tissue structure and lubrication. An understanding of how HA contributes to the structure of other musculoskeletal tissues, including muscle, bone, tendon, and intervertebral discs, is growing. In addition, the use of HA-based therapies to restore damaged tissue is becoming more prevalent. Nevertheless, the relationship between biomechanical stimuli and HA synthesis, degradation, and signaling in musculoskeletal tissues remains understudied, limiting the utility of HA in regenerative medicine. In this review, we discuss the various roles and significance of endogenous HA in musculoskeletal tissues. We use what is known and unknown to motivate new lines of inquiry into HA biology within musculoskeletal tissues and in the mechanobiology governing HA metabolism by suggesting questions that remain regarding the relationship and interaction between biological and mechanical roles of HA in musculoskeletal health and disease.

Receptor for hyaluronan-mediated motility (RHAMM) defines an invasive niche associated with tumor progression and predicts poor outcomes in breast cancer patients

Breast cancer invasion and metastasis result from a complex interplay between tumor cells and the tumor microenvironment (TME). Key oncogenic changes in the TME include aberrant synthesis, processing, and signaling of hyaluronan (HA). Hyaluronan-mediated motility receptor (RHAMM, CD168; HMMR) is an HA receptor enabling tumor cells to sense and respond to this aberrant TME during breast cancer progression. Previous studies have associated RHAMM expression with breast tumor progression; however, cause and effect mechanisms are incompletely established. Focused gene expression analysis of an internal breast cancer patient cohort confirmed that increased RHAMM expression correlates with aggressive clinicopathological features. To probe mechanisms, we developed a novel 27-gene RHAMM-related signature (RRS) by intersecting differentially expressed genes in lymph node (LN)-positive patient cases with the transcriptome of a RHAMM-dependent model of cell transformation, which we validated in an independent cohort. We demonstrate that the RRS predicts for poor survival and is enriched for cell cycle and TME-interaction pathways. Further analyses using CRISPR/Cas9-generated RHAMM-/- breast cancer cells provided direct evidence that RHAMM promotes invasion in vitro and in vivo. Immunohistochemistry studies highlighted heterogeneous RHAMM protein expression, and spatial transcriptomics associated the RRS with RHAMM-high microanatomic foci. We conclude that RHAMM upregulation leads to the formation of 'invasive niches', which are enriched in RRS-related pathways that drive invasion and could be targeted to limit invasive progression and improve patient outcomes. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

CD44 mediates hyaluronan to promote the differentiation of human amniotic mesenchymal stem cells into chondrocytes

OBJECTIVES

CD44 is the major receptor for hyaluronan (HA), but its effect on HA-induced differentiation of human amnion mesenchymal stem cells into chondrocytes is unclear. This study aimed to investigate the effects and mechanisms of CD44 in HA-induced chondrogenesis.

METHODS

Immunocytochemistry and toluidine blue staining were used to assess the secretion of type II collagen and aggrecan, respectively. qRT-PCR and western blotting were performed to evaluate the expression of key genes and proteins.

RESULTS

The expression of aggrecan and type II collagen was downregulated after using the anti-CD44 antibody (A3D8). The transcriptional levels of chondrocytes‑associated genes SRY‑box transcription factor 9, aggrecan, and collagen type II alpha 1 chain were also decreased. Thus, CD44 may mediate HA-induced differentiation of hAMSCs into chondrocytes. Further investigation indicated that expression of phosphorylated (p)‑Erk1/2 and p‑Smad2 decreased following CD44 inhibition. The changes in the expression of p-Erk1/2 and p-Smad2 were consistent after using the ERK1/2 inhibitor (U0126) and agonist (EGF), respectively. After administering the p-Smad2 inhibitor, the expression levels of p-ERK1/2 and p-Smad2 appeared downregulated. The results showed crosstalk between Erk1/2 and Smad2. Moreover, inhibition of p-Erk1/2 and p-Smad2 significantly reduced the accumulation of aggrecan and type II collagen.

CONCLUSION

These data indicate that CD44 mediates HA-induced differentiation of hAMSCs into chondrocytes by regulating Erk1/2 and Smad2 signaling.

An original amino acid formula favours in vitro corneal epithelial wound healing by promoting Fn1, ITGB1, and PGC-1α expression

Corneal disorders are frequent, involving most diabetic patients; among its manifestations, they include delayed wound healing. Since maintenance of mitochondrial homeostasis is fundamental for the cell, stimulation of mitochondrial biogenesis represents a unique therapeutic tool for preventing and treating disorders with a deficit in energy metabolism. We have recently demonstrated that a branched-chain amino acid (BCAA)-enriched mixture (BCAAem) supported mitochondrial biogenesis in cardiac and skeletal muscle, reduced liver damage caused by alcohol, and prevented the doxorubicin-dependent mitochondrial damage in cardiomyocytes. The present study aimed to investigate a new amino acid mixture, named six amino acids (6AA), to promote corneal epithelial wound healing by regulating mitochondrial biogenesis. A murine epithelium cell line (TKE2) exposed to this mixture showed increased mitochondrial biogenesis markers, fibronectin 1 (Fn1) and integrin beta 1 (ITGB1) involved in extracellular matrix synthesis and cell migration. Most importantly, the 6AA mixture completely restored the wound in scratch assays, confirming the potential of this new formula in eye disorders like keratopathy. Moreover, our results demonstrate for the first time that peroxisome proliferator-receptor γ coactivator 1 α (PGC-1α) is expressed in TKE2 cells, which controls mitochondrial function and corneal repair process. These results could be relevant for the treatment mainly focused on corneal re-epithelialisation.

Mapping the biogenesis of forward programmed megakaryocytes from induced pluripotent stem cells

Platelet deficiency, known as thrombocytopenia, can cause hemorrhage and is treated with platelet transfusions. We developed a system for the production of platelet precursor cells, megakaryocytes, from pluripotent stem cells. These cultures can be maintained for >100 days, implying culture renewal by megakaryocyte progenitors (MKPs). However, it is unclear whether the MKP state in vitro mirrors the state in vivo, and MKPs cannot be purified using conventional surface markers. We performed single-cell RNA sequencing throughout in vitro differentiation and mapped each state to its equivalent in vivo. This enabled the identification of five surface markers that reproducibly purify MKPs, allowing us insight into their transcriptional and epigenetic profiles. Last, we performed culture optimization, increasing MKP production. Together, this study has mapped parallels between the MKP states in vivo and in vitro and allowed the purification of MKPs, accelerating the progress of in vitro-derived transfusion products toward the clinic.

RHAMMB-mediated bifunctional nanotherapy targeting Bcl-xL and mitochondria for pancreatic neuroendocrine tumor treatment

The incidence of pancreatic neuroendocrine tumor (PNET) has continued to rise. Due to their indolent feature, PNET patients often present with incurable, metastatic diseases. Novel therapies are urgently needed. We have previously shown that Receptor for Hyaluronic Acid-Mediated Motility isoform B (RHAMM^B) and Bcl-xL are upregulated in PNETs and both of them promote PNET metastasis. Because RHAMM protein is undetectable in most adult tissues, we hypothesized that RHAMM^B could be a gateway for nanomedicine delivery into PNETs. To test this, we developed a RHAMM^B-targeting nanoparticle (NP). Inside this NP, we assembled small interfering RNA (siRNA) against Bcl-xL (siBcl-xL) and mitochondria-fusing peptide KLA. We demonstrated that RHAMM^B-positive PNETs picked up the RHAMM^B-targeting NPs. siBcl-xL or KLA alone killed only 30% of PNET cells. In contrast, a synergistic killing effect was achieved with the co-delivery of siBcl-xL and KLA peptide in vitro. Unexpectedly, siBcl-xL induced cell death before reducing Bcl-xL protein levels. The systemically injected RHAMM^B-targeting NPs carrying siBcl-xL and KLA peptide significantly reduced tumor burden in mice bearing RHAMM^B-positive PNETs. Together, these findings indicate that the RHAMM^B-targeting nanotherapy serves as a promising drug delivery system for PNET and possibly other malignancies with upregulated RHAMM^B. The combination of siBcl-xL and KLA peptide can be a therapy for PNET treatment.

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.

High levels of truncated RHAMM cooperate with dysfunctional p53 to accelerate the progression of pancreatic cancer

Pancreatic cancer has the lowest survival rate out of all types of cancer. Pancreatic cancer patients are often diagnosed at advanced stages, hence an urgent need for a better therapeutic development of this devastating disease. Receptor for hyaluronan-mediated motility (RHAMM), not expressed in adult normal pancreas, has been suggested as a prognostic factor and a potential therapeutic target for pancreatic ductal adenocarcinoma (PDAC) and pancreatic neuroendocrine tumor (PNET). In this study, we initially sought to determine whether genetic deletion of RHAMM would slow down pancreatic cancer progression using Rhamm^-/- mice. However, we found that Rhamm^-/- mice expressed a truncated HMMR^Δexon8-16 protein at higher abundance levels than wild-type RHAMM. While HMMR^Δexon8-16 did not enable malignant progression of pancreatic intraepithelial neoplasia in p48-Cre; LSL-KRAS^G12D mice, it accelerated the formation of invasive PDAC and shortened the survival of p48-Cre; LSL-KRAS^G12D mice with heterozygous p53 knockout. Kras^G12D PDAC mice with homozygous p53 knockout mice died around 10 weeks, and the effect of HMMR^Δexon8-16 was not apparent in these short lifespan mice. In addition, HMMR^Δexon8-16 shortened the survival of PNET-bearing RIP-Tag mice, which had inactivated p53. In our analysis of TCGA dataset, pancreatic cancer patients with mutant TP53 or loss of one copy of TP53 had higher RHAMM expression, which, combined, predicted worse outcomes. Taken together, by collaborating with dysfunctional p53, high levels of HMMR^Δexon8-16 , which lacks the centrosome targeting domain and degrons for interaction with the Anaphase-Promoting Complex (APC), accelerated pancreatic cancer progression.

Expression of the Receptor for Hyaluronic Acid-Mediated Motility (RHAMM) in Endometrial Cancer is Associated With Adverse Histologic Parameters and Tumor Progression

Endometrial cancer is one of the most common gynecologic malignancies worldwide. Only 2 agents have been approved by Food and Drug Administration for endometrial cancer since 1971. There is a need to identify molecular targets to treat advanced endometrial cancer. The receptor for hyaluronic acid-mediated motility (RHAMM) is upregulated in various types of cancer. Here, we aimed to determine the clinical significance of RHAMM expression in endometrial cancer. Two hundred twenty-five cases of endometrial cancer, including serous and endometrioid types, and 8 cases of normal endometrium were used for studying RHAMM protein levels. The Cancer Genome Atlas database was also queried for RHAMM mRNA expression in endometrial cancer. Increased expression of RHAMM protein was seen in endometrial cancer compared with no or weak expression in normal endometrium. RHAMM expression positively correlated with tumor grade. RHAMM expression was significantly increased in endometrial serous carcinomas, which are high-grade, aggressive types of endometrial cancer, compared with the relatively less aggressive endometrioid carcinomas. RHAMM expression also correlated with the presence of lymphovascular invasion. RHAMM mRNA expression correlated with decreased survival in The Cancer Genome Atlas cohort. Therefore, increased RHAMM expression in endometrial cancer is associated with high-grade tumors and is indicative of more aggressive behavior. These findings suggest RHAMM as a prognostic factor in endometrial cancer and as a potential therapeutic target in advanced endometrial cancer for future studies.

Co-localization and crosstalk between CD44 and RHAMM depend on hyaluronan presentation

CD44 and the receptor for hyaluronic acid-mediated motility (RHAMM) are the main hyaluronan (HA) receptors. They are commonly overexpressed in different cancers activating signaling pathways related to tumor progression, metastasis and chemoresistance. Besides their involvement in signal transduction via interaction with HA, currently, there is a little information about the possible crosstalk between CD44 and RHAMM and the role of HA in this process. In the present work, we used immunocytochemistry combined with Förster resonance energy transfer (FRET) microscopy and co-immunoprecipitation to elucidate the involvement of HA in CD44 and RHAMM expression, co-localization and crosstalk. We studied breast cancer cells lines with different degrees of invasiveness and expression of these receptors in the absence of exogenous HA and compared the data with the results obtained for cultures supplemented with either soluble HA or seeded on substrates with end-on immobilized HA. Our results demonstrated that cells response depends on the HA presentation: CD44/RHAMM complexation was upregulated in all cell lines upon interaction with immobilized HA, but not with its soluble form. Moreover, the results showed that the expression of both CD44 and RHAMM is regulated via interactions with HA indicating cell-specific feedback loop(s) in the signaling cascade.

A novel mutation combining with rs66612022 in a Chinese pedigree suggests a new pathogenesis to osteogenesis imperfecta via whole genome sequencing

Osteogenesis imperfecta (OI) is a rare heritable disease with systemic connective tissue disorder. Most of the patients represent autosomal dominant form of OI, and are usually resulting from the mutations in type I collagen genes. However, the gene mutations reported previously only account for ∼70% of the OI cases. Here, in a Chinese OI family, we examined seven patients and nine normal individuals using the whole genome sequencing and molecular genetic analysis. The mutation of rs66612022 (COL1A2:p.Gly328Ser) related to glycine substitution was found in the seven patients. Moreover, we identified a novel missense mutation (HMMR:p.Glu2Gln). Interestingly, the individuals of this family with both the mutations were suffering from OI, while the others carried one or none of them are normal. The mutations of COL1A2 and HMMR and their combined effect on OI would further expand the genetic spectrum of OI.

Hyaluronan biology: A complex balancing act of structure, function, location and context

Cell-matrix interactions are fundamental to many developmental, homeostatic, immune and pathologic processes. Hyaluronan (HA), a critical component of the extracellular matrix (ECM) that regulates normal structural integrity and development, also regulates tissue responses during injury, repair, and regeneration. Though simple in its primary structure, HA regulates biological responses in a highly complex manner with balanced contributions from its molecular size and concentration, synthesis versus enzymatic and/or oxidative-nitrative fragmentation, interactions with key HA binding proteins and cell associated receptors, and its cell context-specific signaling. This review highlights the different, but inter-related factors that dictate the biological activity of HA and introduces the overarching themes that weave throughout this special issue of Matrix Biology on hyaluronan.

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.

A truncated RHAMM protein for discovering novel therapeutic peptides

The receptor for hyaluronan mediated motility (RHAMM, gene name HMMR) belongs to a group of proteins that bind to hyaluronan (HA), a high-molecular weight anionic polysaccharide that has pro-angiogenic and inflammatory properties when fragmented. We propose to use a chemically synthesized, truncated version of the protein (706-767), 7 kDa RHAMM, as a target receptor in the screening of novel peptide-based therapeutic agents. Chemical synthesis by Fmoc-based solid-phase peptide synthesis, and optimization using pseudoprolines, results in RHAMM protein of higher purity and yield than synthesis by recombinant protein production. 7 kDa RHAMM was evaluated for its secondary structure, ability to bind the native ligand, HA, and its bioactivity. This 62-amino acid polypeptide replicates the HA binding properties of both native and recombinant RHAMM protein. Furthermore, tubulin-derived HA peptide analogues that bind to recombinant RHAMM and were previously reported to compete with HA for interactions with RHAMM, bind with a similar affinity and specificity to the 7 kDa RHAMM. Therefore, in terms of its key binding properties, the 7 kDa RHAMM mini-protein is a suitable replacement for the full-length recombinant protein.

Immunohistochemical analysis of RHAMM expression in normal and neoplastic human tissues: a cell cycle protein with distinctive expression in mitotic cells and testicular germ cells

Expression of Receptor for Hyaluronic Acid Mediated Motility (RHAMM) increases cellular motility and RHAMM overexpression promotes invasive phenotype and metastasis of cancer cells. RHAMM has been suggested as a biomarker for poor prognosis in several tumor types, including lung, breast, colorectal, gastric, pancreatic ductal, and ovarian cancers. RNA studies showed restricted RHAMM expression in normal tissues, but its protein expression data in tissues were limited. In light of its potential as a prognostic marker and a therapeutic target, we performed immunohistochemical analysis to systematically characterize RHAMM expression in normal and neoplastic human tissues. Among 29 normal adult tissues, RHAMM protein showed restricted expression and was observed in the thymus, lymph node/tonsil, small intestine, colon, skin, bone marrow, placenta, and testis. The cellular distribution patterns of RHAMM in these normal tissues were consistent with RHAMM being a G2/M cell cycle protein, and this was further supported in comparison to the expression of cyclin B2, another G2/M protein. However, unlike the subcellular localization of cyclin B2, RHAMM decorated mitotic spindles in both anaphase and metaphase. RHAMM expression in tumor tissues is variable; and higher RHAMM protein expression is associated with histologically higher-grade tumors in general. Distinct from its expression in somatic tissues, RHAMM showed diffuse, strong, stage-specific expression in the spermatocyte stage of germ cells in adult testis. The neoplastic counterpart, spermatocytic tumor, also showed strong RHAMM expression. This unique expression in testis suggests that RHAMM may function during normal testicular germ cell maturation.

Expression of the receptor for hyaluronic acid mediated motility (RHAMM) is associated with poor prognosis and metastasis in non-small cell lung carcinoma

The receptor for hyaluronic acid-mediated motility (RHAMM) is upregulated in various cancers, but its role in primary and metastatic non-small cell lung carcinoma (NSCLC) remains to be determined. Here, we investigate the clinical relevance of RHAMM expression in NSCLC. RHAMM protein expression correlates with histological differentiation stages and extent of the primary tumor (T stages) in 156 patients with primary NSCLC. Importantly, while focal RHAMM staining pattern is present in 57% of primary NSCLC, intense RHAMM protein expression is present in 96% of metastatic NSCLC cases. In a publicly available database, The Cancer Genome Atlas (TCGA), RHAMM mRNA expression is 12- and 10-fold higher in lung adenocarcinoma and squamous lung carcinoma than in matched normal lung tissues, respectively. RHAMM mRNA expression correlates with stages of differentiation and inferior survival in more than 400 cases of lung adenocarcinoma in the Director's Challenge cohort. Of 4 RHAMM splice variants, RHAMMv3 (also known as RHAMMB) is the dominant variant in NSCLC. Moreover, shRNA-mediated knockdown of RHAMM reduced the migratory ability of two lung adenocarcinoma cell lines, H1975 and H3255. Taken together, RHAMM, most likely RHAMMv3 (RHAMMB), can serve as a prognostic factor for lung adenocarcinomas and a potential therapeutic target in NSCLC to inhibit tumor migration.

Hypoxia Potentiates Anabolic Effects of Exogenous Hyaluronic Acid in Rat Articular Cartilage

Hyaluronic acid (HA) is used clinically to treat osteoarthritis (OA), but its pharmacological effects under hypoxic conditions remain unclear. Articular chondrocytes in patients with OA are exposed to a hypoxic environment. This study investigated whether hypoxia could potentiate the anabolic effects of exogenous HA in rat articular cartilage and whether these mechanisms involved HA receptors. HA under hypoxic conditions significantly enhanced the expression of extracellular matrix genes and proteins in explant culture, as shown by real-time reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, and dimethylmethylene blue (DMMB) assays. Staining with Safranin-O and immunohistochemical staining with antibody to type II collagen were also enhanced in pellet culture. The expression of CD44 was increased by hypoxia and significantly suppressed by transfection with siRNAs targeting hypoxia-inducible factor 1 alpha (siHIF-1α). These findings indicate that hypoxia potentiates the anabolic effects of exogenous HA by a mechanism in which HIF-1α positively regulates the expression of CD44, enhancing the binding affinity for exogenous HA. The anabolic effects of exogenous HA may increase as OA progresses.

Candidate genes and pathogenesis investigation for sepsis-related acute respiratory distress syndrome based on gene expression profile

Background

Acute respiratory distress syndrome (ARDS) is a potentially devastating form of acute inflammatory lung injury as well as a major cause of acute respiratory failure. Although researchers have made significant progresses in elucidating the pathophysiology of this complex syndrome over the years, the absence of a universal detail disease mechanism up until now has led to a series of practical problems for a definitive treatment. This study aimed to predict some genes or pathways associated with sepsis-related ARDS based on a public microarray dataset and to further explore the molecular mechanism of ARDS.

Results

A total of 122 up-regulated DEGs and 91 down-regulated differentially expressed genes (DEGs) were obtained. The up- and down-regulated DEGs were mainly involved in functions like mitotic cell cycle and pathway like cell cycle. Protein–protein interaction network of ARDS analysis revealed 20 hub genes including cyclin B1 (CCNB1), cyclin B2 (CCNB2) and topoisomerase II alpha (TOP2A). A total of seven transcription factors including forkhead box protein M1 (FOXM1) and 30 target genes were revealed in the transcription factor-target gene regulation network. Furthermore, co-cited genes including CCNB2-CCNB1 were revealed in literature mining for the relations ARDS related genes.

Conclusions

Pathways like mitotic cell cycle were closed related with the development of ARDS. Genes including CCNB1, CCNB2 and TOP2A, as well as transcription factors like FOXM1 might be used as the novel gene therapy targets for sepsis related ARDS.

Receptor for Hyaluronic Acid-Mediated Motility is Associated with Poor Survival in Pancreatic Ductal Adenocarcinoma

Receptor for hyaluronic acid (HA)-mediated motility (RHAMM) is a nonintegral cell surface receptor involved in the aggressive phenotype in a wide spectrum of human malignancies, but the significance of RHAMM in pancreatic ductal adenocarcinoma (PDAC) remains unknown. In this study, we investigated the expression of RHAMM and its clinical relevance in PDAC. RHAMM mRNA expression was examined in 8 PDAC cell lines and in primary pancreatic cancer and adjacent non-tumor tissues from 14 patients using real-time RT-PCR. Western blotting was carried out to analyze the expression of RHAMM protein in PDAC cell lines. We also investigated the expression patterns of RHAMM protein in tissue samples from 70 PDAC patients using immunohistochemistry. The RHAMM mRNA expression was increased in some PDAC cell lines as compared to a non-tumorous pancreatic epithelial cell line HPDE. The RHAMM mRNA expression was significantly higher in PDAC tissues as compared to corresponding non-tumorous pancreatic tissues (P < 0.0001). The RHAMM protein expression was higher in the vast majority of PDAC cell lines relative to the expression in HPDE. The immunohistochemical analysis revealed strong expression of RHAMM in 52 (74%) PDAC tissues. Strong expression of RHAMM was significantly associated with a shorter survival time (P = 0.038). In multivariate analysis, tumor stage (P = 0.039), residual tumor (P = 0.015), and strong RHAMM expression (P = 0.034) were independent factors predicting poor survival. Strong expression of RHAMM may predict poor survival in PDAC patients and may provide prognostic and, possibly, therapeutic value.

Hyaluronan/RHAMM interactions in mesenchymal tumor pathogenesis: role of growth factors

Fibrosarcoma belongs to the sarcoma cancer group, which are spindle cell malignancies of mesenchymal origin, and owe their name to the predominant cell line that is present within the tumor. The extracellular matrix (ECM) is a complicated structure that surrounds and supports cells within tissues. Its main components are proteoglycans, collagens, glycoproteins, hyaluronan (HA), and several matrix-degrading enzymes. During cancer progression, significant changes can be observed in the structural and mechanical properties of ECM components. The ECM provides a physical scaffold to which tumor cells attach and migrate. Thus, it is required for key cellular events such as cell motility, adhesion, proliferation, invasion, and metastasis. Importantly, fibrosarcomas were shown to have a high content and turnover of ECM components including HA, proteoglycans, collagens, fibronectin, and laminin. In this review, we will focus on the HA component of fibrosarcoma ECM and critically discuss its role and involved mechanisms during fibrosarcoma pathogenesis.

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.

Biological functions of hyaluronan and cytokine-inducible deubiquitinating enzymes

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

CD44 and RHAMM hyaluronan receptors in human ocular surface inflammation

BACKGROUND

CD44 and RHAMM hyaluronan (HA) receptors have been studied in several systemic diseases such as osteoarthritis and cancer. However, not too much is known about their role in ocular surface disorders. The purpose of this research was to determine if CD44 and RHAMM are implicated in human ocular surface inflammation.

METHODS

Upper tarsal conjunctival epithelial samples from patients with active ocular surface inflammation (n = 17) and healthy controls (n = 14) were recovered by brush cytology. Patients were evaluated by an ophthalmologist and classified in different groups according to the etiology (immune atopic diseases or immune non-atopic diseases) and inflammation intensity (mild/moderate or severe). CD44, RHAMM, and p53 mRNAs were measured using real-time PCR.

RESULTS

CD44, RHAMM, and p53 mRNAs were detected in all samples. In immune atopic diseases, higher levels of CD44 and RHAMM mRNAs were present, reaching a 300 % increase for RHAMM in severe inflammation (p < 0.001). In contrast, in immune non-atopic diseases, the HA receptors were downregulated. CD44 tended to decrease up to 30 % in severe patients (p = 0.06), and RHAMM decreased 40 % in severe inflammation (p = 0.021).

CONCLUSIONS

RHAMM may be implicated in severe ocular surface inflammation affecting the upper tarsal conjunctiva.

Hyaluronan: a simple polysaccharide with diverse biological functions

Hyaluronan (HA) is a linear polysaccharide with disaccharide repeats of d-glucuronic acid and N-acetyl-d-glucosamine. It is evolutionarily conserved and abundantly expressed in the extracellular matrix (ECM), on the cell surface and even inside cells. Being a simple polysaccharide, HA exhibits an astonishing array of biological functions. HA interacts with various proteins or proteoglycans to organize the ECM and to maintain tissue homeostasis. The unique physical and mechanical properties of HA contribute to the maintenance of tissue hydration, the mediation of solute diffusion through the extracellular space and the lubrication of certain tissues. The diverse biological functions of HA are manifested through its complex interactions with matrix components and resident cells. Binding of HA with cell surface receptors activates various signaling pathways, which regulate cell function, tissue development, inflammation, wound healing and tumor progression and metastasis. Taking advantage of the inherent biocompatibility and biodegradability of HA, as well as its susceptibility to chemical modification, researchers have developed various HA-based biomaterials and tissue constructs with promising and broad clinical potential. This paper illustrates the properties of HA from a matrix biology perspective by first introducing the principles underlying the biosynthesis and biodegradation of HA, as well as the interactions of HA with various proteins and proteoglycans. It next highlights the roles of HA in physiological and pathological states, including morphogenesis, wound healing and tumor metastasis. A deeper understanding of the mechanisms underlying the roles of HA in various physiological processes can provide new insights and tools for the engineering of complex tissues and tissue models.

Inhibition of HAS2 induction enhances the radiosensitivity of cancer cells via persistent DNA damage

Hyaluronan synthase 2 (HAS2), a synthetic enzyme for hyaluronan, regulates various aspects of cancer progression, including migration, invasion and angiogenesis. However, the possible association of HAS2 with the response of cancer cells to anticancer radiotherapy, has not yet been elucidated. Here, we show that HAS2 knockdown potentiates irradiation-induced DNA damage and apoptosis in cancer cells. Upon exposure to radiation, all of the tested human cancer cell lines exhibited marked (up to 10-fold) up-regulation of HAS2 within 24h. Inhibition of HAS2 induction significantly reduced the survival of irradiated radioresistant and -sensitive cells. Interestingly, HAS2 depletion rendered the cells to sustain irradiation-induced DNA damage, thereby leading to an increase of apoptotic death. These findings indicate that HAS2 knockdown sensitizes cancer cells to radiation via persistent DNA damage, further suggesting that the irradiation-induced up-regulation of HAS2 contributes to the radioresistance of cancer cells. Thus, HAS2 could potentially be targeted for therapeutic interventions aimed at radiosensitizing cancer cells.

The roles of hyaluronan/RHAMM/CD44 and their respective interactions along the insidious pathways of fibrosarcoma progression

Fibrosarcomas are rare malignant mesenchymal tumors originating from fibroblasts. Importantly, fibrosarcoma cells were shown to have a high content and turnover of extracellular matrix (ECM) components including hyaluronan (HA), proteoglycans, collagens, fibronectin, and laminin. ECMs are complicated structures that surround and support cells within tissues. During cancer progression, significant changes can be observed in the structural and mechanical properties of the ECM components. Importantly, hyaluronan deposition is usually higher in malignant tumors as compared to benign tissues, predicting tumor progression in some tumor types. Furthermore, activated stromal cells are able to produce tissue structure rich in hyaluronan in order to promote tumor growth. Key biological roles of HA result from its interactions with its specific CD44 and RHAMM (receptor for HA-mediated motility) cell-surface receptors. HA-receptor downstream signaling pathways regulate in turn cellular processes implicated in tumorigenesis. Growth factors, including PDGF-BB, TGFβ2, and FGF-2, enhanced hyaluronan deposition to ECM and modulated HA-receptor expression in fibrosarcoma cells. Indeed, FGF-2 through upregulation of specific HAS isoforms and hyaluronan synthesis regulated secretion and net hyaluronan deposition to the fibrosarcoma pericellular matrix modulating these cells' migration capability. In this paper we discuss the involvement of hyaluronan/RHAMM/CD44 mediated signaling in the insidious pathways of fibrosarcoma progression.

Loss of the hyaluronan receptor RHAMM prevents constrictive artery wall remodeling

OBJECTIVE

Constrictive extracellular matrix (ECM) remodeling contributes significantly to restenosis after arterial reconstruction, but its molecular regulation is poorly defined. Hyaluronan (HA) accumulates within ECM at sites of injury where it is thought to facilitate smooth muscle cell (SMC) trafficking and collagen remodeling analogous to its role in cutaneous wound healing. SMC receptors for HA include receptor for hyaluronan-mediated motility (RHAMM), which mediates HA-induced migration. We hypothesized RHAMM would also mediate SMC-matrix interactions to alter the extent of constrictive remodeling.

METHODS

We studied the role of RHAMM in SMC attachment to collagen, migration, and contraction of collagen gels using blocking antibodies and SMC from RHAMM -/- knockout mice. We then determined the role of RHAMM in constrictive artery wall remodeling by comparing changes in wall geometry in RHAMM -/- vs wild-type (WT) RHAMM +/+ controls 1 month after carotid ligation.

RESULTS

HA increased SMC attachment to collagen-coated plates, but blocking RHAMM reduced adhesion (P = .025). RHAMM -/- SMC also demonstrated reduced adhesion (% adherent: 36.1 ± 2.2 vs 76.3 ± 1.9; P < .05). SMC contraction of collagen gels was enhanced by HA and further increased by RHAMM blockade (P < .01) or knockout (gel diameter, mm: RHAMM -/-, 6.7 ± 0.1 vs WT 9.8 ± 0.1; P < .01). RHAMM promoted constrictive remodeling in vivo as carotid artery size was significantly larger in knockout mice 1 month after ligation. Neointimal thickening, however, was not affected in RHAMM -/- (P = NS vs WT), but lumen size was significantly larger (lumen area, μm(2): 52.4 ± 1.4 × 10(3) vs 10.4 ± 1.8 × 10(3); P = .01) because artery size constricted less (external elastic lamina area, μm(2): RHAMM -/-, 92.4 ± 4.7 × 10(3) vs WT, 51.3 ± 5.9 × 10(3); P = .015). Adventitial thickening and collagen deposition were also more extensive in ligated RHAMM -/- carotids (adventitial thickness, μm: 218 ± 12.2 vs 109 ± 7.9; P = .01).

CONCLUSIONS

HA activation of RHAMM significantly impacts SMC-ECM adhesive interactions and contributes to constrictive artery wall remodeling in mice. Strategies to block RHAMM at sites of vessel injury may prove useful in the prevention of clinical restenosis.

Immune responses to RHAMM in patients with acute myeloid leukemia after chemotherapy and allogeneic stem cell transplantation

Leukemic blasts overexpress immunogenic antigens, so-called leukemia-associated antigens like the receptor for hyaluronan acid-mediated motility (RHAMM). Persistent RHAMM expression and decreasing CD8⁺ T-cell responses to RHAMM in the framework of allogeneic stem cell transplantation or chemotherapy alone might indicate the immune escape of leukemia cells. In the present study, we analyzed the expression of RHAMM in 48 patients suffering from acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Furthermore, we correlated transcripts with the clinical course of the disease before and after treatment. Real-time quantitative reverse transcriptase polymerase chain reaction was performed from RNA of peripheral blood mononuclear cells. T cell responses against RHAMM were assessed by tetramer staining (flow cytometry) and enzyme-linked immunospot (ELISPOT) assays. Results were correlated with the clinical outcome of patients. The results of the present study showed that almost 60% of the patients were RHAMM positive; specific T-cells recognizing RHAMM could be detected, but they were nonfunctional in terms of interferon gamma or granzyme B release as demonstrated by ELISPOT assays. Immunotherapies like peptide vaccination or adoptive transfer of RHAMM-specific T cells might improve the immune response and the outcome of AML/MDS patients.

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.

Differential gene expression in oligodendrocyte progenitor cells, oligodendrocytes and type II astrocytes

Oligodendrocyte precursor cells (OPCs) are bipotential progenitor cells that can differentiate into myelin-forming oligodendrocytes or functionally undetermined type II astrocytes. Transplantation of OPCs is an attractive therapy for demyelinating diseases. However, due to their bipotential differentiation potential, the majority of OPCs differentiate into astrocytes at transplanted sites. It is therefore important to understand the molecular mechanisms that regulate the transition from OPCs to oligodendrocytes or astrocytes. In this study, we isolated OPCs from the spinal cords of rat embryos (16 days old) and induced them to differentiate into oligodendrocytes or type II astrocytes in the absence or presence of 10% fetal bovine serum, respectively. RNAs were extracted from each cell population and hybridized to GeneChip with 28,700 rat genes. Using the criterion of fold change > 4 in the expression level, we identified 83 genes that were up-regulated and 89 genes that were down-regulated in oligodendrocytes, and 92 genes that were up-regulated and 86 that were down-regulated in type II astrocytes compared with OPCs. The up-regulated genes, such as activating transcription factor 3 and myelin basic protein in oligodendrocytes or claudin 11 in type II astrocytes, might contribute to OPC differentiation and represent constitutive components of oligodendrocytes or type II astrocytes. The down-regulated genes in both oligodendrocytes and type II astrocytes, such as transcription factor 19, might be involved in maintaining self-renewal and/or represent the property of OPCs. These results provide new insights into the elucidation of the molecular mechanisms, by which OPCs differentiate to oligodendrocytes or type II astrocytes.

Mechanisms involved in suppression of NGF-induced neuronal differentiation of PC12 cells by hyaluronic acid

In the present study, we found that hyaluronic acid (HA) suppressed the neuronal differentiation mediated by nerve growth factor (NGF). In addition, we examined the mechanism by which HA inhibits the NGF-induced neurite outgrowth of PC12 cells. We elucidated the direct interaction between NGF and HA, and found that HA did not bind to NGF directly using a quartz-crystal microbalance. Western blot analysis revealed that HA suppressed NGF-induced phosphorylation of p38 MAPK, ERKs, and transcriptional factor CREB in PC12 cells. Furthermore, HA inhibited the luciferase activity of pCRE-Luc transfected PC12 cells in the presence of NGF. We confirmed that the p38 MAPK inhibitor SB203580 and ERK inhibitor U0126 suppressed NGF-induced neurite outgrowth of PC12 cells, and found that the inhibitory effects of HA on phosphorylation of ERKs, but not of p38 MAPK, were restored by the anti-RHAMM antibody. The number of PC12 cells with neurites increased remarkably when pre-cultured with the anti-RHAMM antibody, then treated with NGF and HA. Our findings indicate that HA inhibits NGF-induced neuronal differentiation of PC12 cells partially by inhibiting ERK phosphorylation through RHAMM, and suggest that the binding of HA to RHAMM modifies the signaling pathways in PC12 cells treated with NGF.

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

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

The role of a cell-associated hyaluronan-binding protein in fibroblast behaviour

In a model culture system hyaluronan has been shown to promote cell ruffling and random cell locomotion. At the same time it promotes both protein tyrosine phosphorylation and phospholipid breakdown. These results indicate that this glycosaminoglycan, in addition to its previously described role as a regulator of adhesion and cytoskeletal organization, may also influence cell behaviour via second messenger formation. A cell-associated hyaluronan-binding protein (cell-HABP) has been isolated from locomoting fibroblasts that may represent one binding site that transduces these effects of hyaluronan. This protein is concentrated in the lamellae and ruffles of migrating fibroblasts but is lost from the cell surface as cell locomotion slows. It is a large (molecular mass estimated at 1-2 x 10(6) daltons) complex of proteins that includes a hyaluronan-binding site and a protein kinase. The protein kinase is responsive to hyaluronan and is related, antigenically, to the pp60src protein kinase. The function of cell-HABP has not been characterized but its location, regulated distribution and enzyme characteristics suggest that it may be involved in hyaluronan-regulated cell locomotion.

Functions of proteoglycans at the cell surface

Proteoglycans (primarily heparan sulphate proteoglycans) are found at the surface of most adherent eukaryotic cells. Earlier studies suggest that these molecules can be associated with the cell surface principally by two different mechanisms. Proteoglycans may occur as membrane-intercalated glycoproteins, where the core protein of the proteoglycan is anchored in the lipid interior of the plasma membrane, or they may be bound via the polysaccharide components of the molecule to specific anchoring proteins present at the cell surface. A number of functions have been proposed for cell surface-associated proteoglycans, including: regulation of cell-substrate adhesion; regulation of cell proliferation; participation in the binding and uptake of extracellular components; and participation in the regulation of extracellular matrix formation. Evidence is discussed suggesting that the cell-associated heparan sulphate helps to connect the intracellular cytoskeleton to the extracellular matrix in focal adhesions. This evidence includes: the co-localization of actin and heparan sulphate proteoglycan during the process of cell spreading, and in isolated focal adhesions; biochemical analyses of a hydrophobic heparan sulphate proteoglycan from isolated focal adhesions; and the formation of focal adhesions on substrates made from isolated fibronectin fragments requires the presence of a heparan sulphate-binding site.

Rhamm-/- fibroblasts are defective in CD44-mediated ERK1,2 motogenic signaling, leading to defective skin wound repair

Rhamm (receptor for hyaluronan-mediated motility) is an hyaluronan binding protein with limited expression in normal tissues and high expression in advanced cancers. To understand its physiological functions and identify the molecular mechanisms underlying these functions, we created mice with a genetic deletion of Rhamm. We show that Rhamm^−/− fibroblasts fail to resurface scratch wounds >3 mm or invade hyaluronan-supplemented collagen gels in culture. We identify a requirement for Rhamm in the localization of CD44 to the cell surface, formation of CD44–ERK1,2 (extracellular-regulated kinase 1,2) complexes, and activation/subcellular targeting of ERK1,2 to the cell nucleus. We also show that cell surface Rhamm, restricted to the extracellular compartment by linking recombinant protein to beads, and expression of mutant active mitogen-activated kinase kinase 1 (Mek1) are sufficient to rescue aberrant signaling through CD44–ERK1,2 complexes in Rh^−/− fibroblasts. ERK1,2 activation and fibroblast migration/differentiation is also defective during repair of Rh^−/− excisional skin wounds and results in aberrant granulation tissue in vivo. These results identify Rhamm as an essential regulator of CD44–ERK1,2 fibroblast motogenic signaling required for wound repair.

Glucose regulated proteins 78 and 75 bind to the receptor for hyaluronan mediated motility in interphase microtubules

The receptor for hyaluronan mediated motility (RHAMM), which is a hyaluronan-binding protein, is a centrosomal and microtubal protein. Here, we have identified two RHAMM-binding proteins, glucose regulated protein (GRP) 78 and GRP75, using co-immunoprecipitation analysis. These two proteins directly bound to glutathione-S-transferase-RHAMM fusion proteins. By double immunostaining, GRP78 and GRP75 colocalized with RHAMM in interphase microtubules, but were separated in mitotic spindles. Prevention of microtubule polymerization by TN-16 and vincristine sulfate induced RHAMM overexpression without a significant change in GRP78/75. Taken together, GRP78/75 and RHAMM complexes may stabilize microtubules in the interphase, associated with a downregulation of RHAMM. These results reveal a new biochemical activity of RHAMM.

Expression of the CD44 Receptor in the Blood Vessel System: An Experimental Study in Rat

The CD44 receptor is a transmembrane glycoprotein expressed on a variety of cells like endothelial, epithelial and smooth muscle cells. This molecule has many important functions, e.g. in cell-cell and cell-matrix interactions and signal transduction. The main ligand for CD44 is hyaluronan (HYA). HYA is a glycosaminoglycan with structural and cell biological properties. The localization of HYA in the vessel wall of arteries and veins in the healthy adult and newborn rat has been described earlier. In this study the occurrence of the CD44 receptor was investigated in the same vessels and compared to the localization of HYA. Both CD44 and its ligand showed an increased expression in the vessel wall of newborn rats compared to that of adult rats. Although HYA is abundant in the adventitia of adult rats, virtually no expression of CD44 was observed. Our results indicate that the CD44 receptor expression is increased during the stage of maturation of the vessel tree whereas the CD44 receptor is less needed by HYA in the healthy vessel wall.

Engineering of Biomaterials Surfaces by Hyaluronan

This review addresses the area of study that defines the field of surface modification of biomedical materials and devices by hyaluronan (HA), as related to the exploitation of HA biological properties. To provide a comprehensive view of the subject matter, initial sections give a quick introduction to basic information on HA-protein and HA-cell interactions, together with some discussion on the bioactive role of HA in wound healing and related phenomena. This is followed by a description of current theories that correlate HA properties to its molecular structure in aqueous media, underlying how HA molecular details are crucial for its biological interaction and role. Finally, existing approaches to surface modification by HA are reviewed, stressing the need for HA-surface engineering founded on the knowledge and control of the surface-linked HA molecular conformation at the solid/aqueous interface.

Receptor for Hyaluronan-Mediated Motility Correlates with Centrosome Abnormalities in Multiple Myeloma and Maintains Mitotic Integrity

Elevated expression of receptor for hyaluronan-mediated motility (RHAMM) within ex vivo diagnostic multiple myeloma plasma cells predicts for aggressive disease and patient survival. Here, we investigate the relationship between RHAMM and centrosomal abnormalities within multiple myeloma patient samples. We report that myeloma patient samples contain pervasive structural and numerical centrosomal abnormalities. Structural, but not numerical, centrosomal abnormalities strongly correlate with elevated RHAMM expression. As others have shown that excess pericentriolar material strongly associates with abnormal mitoses, we modeled centrosomal abnormalities with exogenous RHAMM overexpression. RHAMM overexpression in vitro resulted in centrosomal and mitotic defects. To elucidate a mechanism for RHAMM-mediated spindle defects, we further investigated RHAMM mitotic function. RHAMM mitotic localization mirrors that of targeting protein for Xklp2 (TPX2), and RHAMM interacts with the spindle assembly factors dynein and TPX2. Like TPX2, RHAMM expression is up-regulated during mitosis. Moreover, inhibition of function experiments reveals that RHAMM and TPX2 functions converge to maintain spindle integrity after spindle assembly. We postulate that augmentation of RHAMM expression within human cancers, including myeloma, can directly affect centrosomal structure and spindle integrity and potentially modulate apoptotic and cell cycle progression pathways.

Genetic deletion of receptor for hyaluronan-mediated motility (Rhamm) attenuates the formation of aggressive fibromatosis (desmoid tumor)

Aggressive fibromatosis (desmoid tumor) is a locally invasive soft tissue neoplasm associated with mutations resulting in beta-catenin-mediated transcriptional activation. This tumor is composed of cells with histological and molecular characteristics common to proliferating mesenchymal cells of dermal wounds. Using immunohistochemistry and RT-PCR, we show that Rhamm, a protein with an important role in wound healing and neoplastic progression, is also expressed at high levels in aggressive fibromatosis. A mouse harboring a targeted deletion in Rhamm was generated, resulting in viable Rhamm-/- animals. Rhamm-/- mice were crossed with Apc/Apc1638N mice, which harbor a targeted mutation in the Apc gene predisposing animals to gastrointestinal and aggressive fibromatosis tumors. Rhamm deficiency significantly decreased the number of aggressive fibromatosis tumors formed, but did not alter the number of gastrointestinal polyps. Cell culture studies show that Rhamm regulates cell proliferation in both fibroblasts and fibromatosis cells under conditions of low density, but not high density. These results suggest that Rhamm regulates proliferation of cells with sparse cell-cell contacts, such as occurs in aggressive fibromatosis; provides the first genetic evidence implicating Rhamm in tumor pathology; and suggest Rhamm blockade as a potential therapeutic target for this otherwise difficult-to-treat neoplasm.

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.