Identification, design and synthesis of tubulin-derived peptides as novel hyaluronan mimetic ligands for the receptor for hyaluronan-mediated motility (RHAMM/HMMR)

A biological guide to glycosaminoglycans: current perspectives and pending questions

Mammalian glycosaminoglycans (GAGs), except hyaluronan (HA), are sulfated polysaccharides that are covalently attached to core proteins to form proteoglycans (PGs). This article summarizes key biological findings for the most widespread GAGs, namely HA, chondroitin sulfate/dermatan sulfate (CS/DS), keratan sulfate (KS), and heparan sulfate (HS). It focuses on the major processes that remain to be deciphered to get a comprehensive view of the mechanisms mediating GAG biological functions. They include the regulation of GAG biosynthesis and postsynthetic modifications in heparin (HP) and HS, the composition, heterogeneity, and function of the tetrasaccharide linkage region and its role in disease, the functional characterization of the new PGs recently identified by glycoproteomics, the selectivity of interactions mediated by GAG chains, the display of GAG chains and PGs at the cell surface and their impact on the availability and activity of soluble ligands, and on their move through the glycocalyx layer to reach their receptors, the human GAG profile in health and disease, the roles of GAGs and particular PGs (syndecans, decorin, and biglycan) involved in cancer, inflammation, and fibrosis, the possible use of GAGs and PGs as disease biomarkers, and the design of inhibitors targeting GAG biosynthetic enzymes and GAG-protein interactions to develop novel therapeutic approaches.

CD44 and RHAMM Are Microenvironmental Sensors with Dual Metastasis Promoter and Suppressor Functions

The progression of primary tumors to metastases remains a significant roadblock to the treatment of most cancers. Emerging evidence has identified genes that specifically affect metastasis and are potential therapeutic targets for managing tumor progression. However, these genes can have dual tumor promoter and suppressor functions that are contextual in manifestation, and that complicate their development as targeted therapies. CD44 and RHAMM/HMMR are examples of multifunctional proteins that can either promote or suppress metastases, as demonstrated in experimental models. These two proteins can be viewed as microenvironmental sensors and this minireview addresses the known mechanistic underpinnings that may determine their metastasis suppressor versus promoter functions. Leveraging this mechanistic knowledge for CD44, RHAMM, and other multifunctional proteins is predicted to improve the precision of therapeutic targeting to achieve more effective management of metastasis.

The role of RHAMM in cancer: Exposing novel therapeutic vulnerabilities

Receptor for hyaluronic acid-mediated motility (RHAMM) is a cell surface receptor for hyaluronic acid that is critical for cell migration and a cell cycle protein involved in microtubule assembly and stability. These functions of RHAMM are required for cellular stress responses and cell cycle progression but are also exploited by tumor cells for malignant progression and metastasis. RHAMM is often overexpressed in tumors and is an independent adverse prognostic factor for a number of cancers such as breast and prostate. Interestingly, pharmacological or genetic inhibition of RHAMM in vitro and in vivo ablates tumor invasiveness and metastatic spread, implicating RHAMM as a potential therapeutic target to restrict tumor growth and improve patient survival. However, RHAMM’s pro-tumor activity is dependent on its subcellular distribution, which complicates the design of RHAMM-directed therapies. An alternative approach is to identify downstream signaling pathways that mediate RHAMM-promoted tumor aggressiveness. Herein, we discuss the pro-tumoral roles of RHAMM and elucidate the corresponding regulators and signaling pathways mediating RHAMM downstream events, with a specific focus on strategies to target the RHAMM signaling network in cancer cells.

Proteoglycans in Toll-like receptor responses and innate immunity

The extracellular matrix (ECM) is an active and dynamic feature of tissues that not only provides gross structure but also plays key roles in cellular responses. The ever-changing microenvironment responds dynamically to cellular and external signals, and in turn influences cell fate, tissue development, and response to environmental injury or microbial invasion. It is therefore paramount to understand how the ECM components interact with each other, the environment and cells, and how they mediate their effects. Among the ECM components that have recently garnered increased attention, proteoglycans (PGs) deserve special note. Recent evidence strongly suggests that they play a crucial role both in health maintenance and disease development. In particular, proteoglycans dictate whether homeostasis or cell death will result from a given injury, by triggering and modulating activation of the innate immune system, via a conserved array of receptors that recognize exogenous (infectious) or endogenous (tissue damage) molecular patterns. Innate immune activation by proteoglycans has important implications for the understanding of cell-matrix interactions in health and disease. In this review, we will summarize the current state of knowledge of innate immune signaling by proteoglycans, discuss the implications, and explore future directions to define progress in this area of extracellular matrix biology.

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.

Extracellular matrix and its therapeutic potential for cancer treatment

The extracellular matrix (ECM) is one of the major components of tumors that plays multiple crucial roles, including mechanical support, modulation of the microenvironment, and a source of signaling molecules. The quantity and cross-linking status of ECM components are major factors determining tissue stiffness. During tumorigenesis, the interplay between cancer cells and the tumor microenvironment (TME) often results in the stiffness of the ECM, leading to aberrant mechanotransduction and further malignant transformation. Therefore, a comprehensive understanding of ECM dysregulation in the TME would contribute to the discovery of promising therapeutic targets for cancer treatment. Herein, we summarized the knowledge concerning the following: (1) major ECM constituents and their functions in both normal and malignant conditions; (2) the interplay between cancer cells and the ECM in the TME; (3) key receptors for mechanotransduction and their alteration during carcinogenesis; and (4) the current therapeutic strategies targeting aberrant ECM for cancer treatment.

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.

Design of peptide mimetics to block pro-inflammatory functions of HA fragments

Hyaluronan is a simple extracellular matrix polysaccharide that actively regulates inflammation in tissue repair and disease processes. The native HA polymer, which is large (>500 kDa), contributes to the maintenance of homeostasis. In remodeling and diseased tissues, polymer size is strikingly polydisperse, ranging from <10 kDa to >500 kDa. In a diseased or stressed tissue context, both smaller HA fragments and high molecular weight HA polymers can acquire pro-inflammatory functions, which result in the activation of multiple receptors, triggering pro-inflammatory signaling to diverse stimuli. Peptide mimics that bind and scavenge HA fragments have been developed, which show efficacy in animal models of inflammation. These studies indicate both that HA fragments are key to driving inflammation and that scavenging these is a viable therapeutic approach to blunting inflammation in disease processes. This mini-review summarizes the peptide-based methods that have been reported to date for blocking HA signaling events as an anti-inflammatory therapeutic approach.

Thymosin α1 Interacts with Hyaluronic Acid Electrostatically by Its Terminal Sequence LKEKK

Thymosin α1 (Tα1), is a peptidic hormone, whose immune regulatory properties have been demonstrated both in vitro and in vivo and approved in different countries for treatment of several viral infections and cancers. Tα1 assumes a conformation in negative membranes upon insertion into the phosphatidylserine exposure as found in several pathologies and in apoptosis. These findings are in agreement with the pleiotropy of Tα1, which targets both normal and tumor cells, interacting with multiple cellular components, and have generated renewed interest in the topic. Hyaluronan (HA) occurs ubiquitously in the extracellular matrix and on cell surfaces and has been related to a variety of diseases, and developmental and physiological processes. Proteins binding HA, among them CD44 and the Receptor for HA-mediated motility (RHAMM) receptors, mediate its biological effects. NMR spectroscopy indicated preliminarily that an interaction of Tα1 with HA occurs specifically around lysine residues of the sequence LKEKK of Tα1 and is suggestive of a possible interference of Tα1 in the binding of HA with CD44 and RHAMM. Further studies are needed to deepen these observations because Tα1 is known to potentiate the T-cell immunity and anti-tumor effect. The binding inhibitory activity of Tα1 on HA-CD44 or HA-RHAMM interactions can suppress both T-cell reactivity and tumor progression.

[Effect of injectable composites of calcium sulfate and hyaluronate in enhancing osteogenesis]

Objective

To fabricate an injectable composite bone substitute with hyaluronic acid (HA) and calcium sulfate and to evaluate the biocompatibility and effect of the composite on cell proliferation, osteogenic differentiation in vitro and osteogenic capability in vivo.

Methods

Calcium sulfate powder was mixed with HA solution, cross-linked HA solution, and phosphate buffer solution (PBS) in a ratio of 2∶1 ( W/ V) to get composites of CA+HA, CA+HAC, and CA. The standard extracts from above 3 materials were prepared according to ISO10993-5, and were used to culture mouse MC3T3-E1 cells. The composite biocompatibility and cell proliferation in different concentrations of extract were tested with cell counting kit-8 (CCK-8). The cells were cultured with standard medium as a control. The optimal concentration was selected for osteogenic differentiation test, and ELISA Kit was used to determine the alkaline phosphatase (ALP), collagen type I (COL-I), and osteocalcin (OCN). The femoral condylar bone defect was made on New Zealand white rabbits and repaired with CA+HA, CA+HAC, and CA. Micro-CT was done to evaluate new bone formation with bone volume/tissue volume (BV/TV) ratio at 6 and 12 weeks. HE staining was used to observe bone formation.

Results

CA+HA and CA+HAC were better in injectability and stability in PBS than CA. The biocompatibility test showed that absorbance ( A) value of CA group was significantly lower than that of control group ( P<0.05) at 6, 12, and 24 hours after culture, but no significant difference was found in A values between CA+HA group or CA+HAC group and control group ( P>0.05). The proliferation test showed 25% and 50% extract of all 3 materials had significantly higher A value than control group ( P<0.05). For 75% and 100% extract, only CA+HA group had significantly higher A value than control group ( P<0.05). And 50% extract was selected for osteogenic differentiation test. At 14 and 21 days, ALP, COL-I and OCN concentrations of CA+HA group and CA+HAC group were significantly higher than those of CA group and control group ( P<0.05). Micro-CT results showed higher BV/TV in CA+HA group and CA+HAC group than CA group at 6 and 12 weeks ( P<0.05), but no significant difference was found between CA+HA group and CA+HAC group ( P>0.05). HE staining revealed that a little bone tissue was seen in CA+HA group and CA+HAC group, but there was no bone formation in CA group at 6 weeks; more streak bone tissue in CA+HA group and CA+HAC group than CA group at 12 weeks.

Conclusion

Composites prepared with calcium sulfate and HA or with cross-linked HA are stable, injectable, and biocompatible. The materials have excellent effect on proliferation and differentiation of mouse MC3T3-E1 cells. They also show good osteogenic capability in vivo. So it is a potential bone substitutes for bone defective diseases.

RHAMM-target peptides inhibit invasion of breast cancer cells

RHAMM is hyaluronan- receptor with multiple functions in the cell, RHAMM is involved in proliferation, motility, migration, invasion, mitotic spindle formation in tumour cells. Therefore, RHAMM could be a relevant target for molecular targeted therapies against tumors.The role of RHAMM-target peptides in inhibition invasion for preventing breast cancer has not yet been investigated. Base on this, we analyzed the RHAMM-target peptides for their therapeutic activity against breast cancer cells. In the present study, we examined the effect of RHAMM-target peptides on the invasion of breast cancer cells (MDAMB- 231), using confocal microscopy. We shown that RHAMM-target peptides decreased formation of invadopodia of breast cancer cells. The treatment of breast cancer cells by RHAMM -target peptides inhibited the invasion up to 99 %. Additionally, RHAMM-target peptides induced the morphological changes of of breast cancer cells. Therefore, based on these results, we can conclude that RHAMM-target peptides may be potential anti-cancer agents.

Receptor for hyaluronan mediated motility (RHAMM/HMMR) is a novel target for promoting subcutaneous adipogenesis

Hyaluronan, CD44 and the Receptor for Hyaluronan-Mediated Motility (RHAMM, gene name HMMR) regulate stem cell differentiation including mesenchymal progenitor differentiation. Here, we show that CD44 expression is required for subcutaneous adipogenesis, whereas RHAMM expression suppresses this process. We designed RHAMM function blocking peptides to promote subcutaneous adipogenesis as a clinical and tissue engineering tool. Adipogenic RHAMM peptides were identified by screening for their ability to promote adipogenesis in culture assays using rat bone marrow mesenchymal stem cells, mouse pre-adipocyte cell lines and primary human subcutaneous pre-adipocytes. Oil red O uptake into fat droplets and adiponectin production were used as biomarkers of adipogenesis. Positive peptides were formulated in either collagen I or hyaluronan (Orthovisc) gels then assessed for their adipogenic potential in vivo following injection into dorsal rat skin and mammary fat pads. Fat content was quantified and characterized using micro CT imaging, morphometry, histology, RT-PCR and ELISA analyses of adipogenic gene expression. Injection of screened peptides increased dorsal back subcutaneous fat pad area (208.3 ± 10.4 mm²versus control 84.11 ± 4.2 mm²; p < 0.05) and mammary fat pad size (45 ± 11 mg above control background, p = 0.002) in female rats. This effect lasted >5 weeks as detected by micro CT imaging and perilipin 1 mRNA expression. RHAMM expression suppresses while blocking peptides promote expression of PPARγ, C/EBP and their target genes. Blocking RHAMM function by peptide injection or topical application is a novel and minimally invasive method for potentially promoting subcutaneous adipogenesis in lipodystrophic diseases and a complementary tool to subcutaneous fat augmentation techniques.

Carcinoma Cell Hyaluronan as a "Portable" Cancerized Prometastatic Microenvironment

Hyaluronan (HA) is a structurally simple polysaccharide, but its ability to act as a template for organizing pericellular matrices and its regulated synthesis and degradation are key to initiating repair responses. Importantly, these HA functions are usurped by tumor cells to facilitate progression and metastasis. Recent advances have identified the functional complexities associated with the synthesis and degradation of HA-rich matrices. Three enzymes synthesize large HA polymers while multiple hyaluronidases or tissue free radicals degrade these into smaller bioactive fragments. A family of extracellular and cell-associated HA-binding proteins/receptors translates the bioinformation encrypted in this complex polymer mixture to activate signaling networks required for cell survival, proliferation, and migration in an actively remodeling microenvironment. Changes in HA metabolism within both the peritumor stroma and parenchyma are linked to tumor initiation, progression, and poor clinical outcome. We review evidence that metastatic tumor cells must acquire the capability to autonomously synthesize, assemble, and process their own "portable" HA-rich microenvironments to survive in the circulation, metastasize to ectopic sites, and escape therapeutic intervention. Strategies to disrupt the HA machinery of primary tumor and circulating tumor cells may enhance the effectiveness of current conventional and targeted therapies. Cancer Res; 76(9); 2507-12. ©2016 AACR.