The liberation of CD44

LOXL2-induced PEAR1 Ser891 phosphorylation suppresses CD44 degradation and promotes triple-negative breast cancer metastasis

CD44 is associated with a high risk of metastasis, recurrence, and drug resistance in various cancers. Here we report that platelet endothelial aggregation receptor 1 (PEAR1) is a CD44 chaperone protein that protected CD44 from endocytosis-mediated degradation and enhances cleavage of the CD44 intracellular domain (CD44-ICD). Furthermore, we found that lysyl oxidase-like protein 2 (LOXL2), an endogenous ligand of PEAR1, bound to the PEAR1-EMI domain and facilitated the interaction between PEAR1 and CD44 by inducing PEAR1 Ser891 phosphorylation in a manner that was independent of its enzyme activity. Levels of PEAR1 protein and PEAR1 phosphorylation at Ser891 were increased in patients with triple-negative breast cancer (TNBC), were positively correlated with expression of LOXL2 and CD44, and were negatively correlated with overall survival. The level of PEAR1 Ser891 phosphorylation was identified as the best independent prognostic factor in TNBC patients. The prognostic efficacy of the combination of PEAR1 phosphorylation at Ser891 and CD44 expression was superior to that of PEAR1 phosphorylation at Ser891 alone. Blocking the interaction between LOXL2 and PEAR1 with monoclonal antibodies significantly inhibited TNBC metastasis, representing a promising therapeutic strategy for TNBC.

The spatial separation of basic amino acids is similar in RHAMM and hyaluronan binding peptide P15-1 despite different sequences and conformations

Peptides that increase pro-reparative responses to injury and disease by modulating the functional organization of hyaluronan (HA) with its cell surface binding proteins (e.g., soluble receptor for hyaluronan-mediated motility [RHAMM] and integral membrane CD44) have potential therapeutic value. The binding of RHAMM to HA is an attractive target, since RHAMM is normally absent or expressed at low levels in homeostatic conditions, but its expression is significantly elevated in the extracellular matrix during tissue stress, response-to-injury, and in cancers and inflammation-based diseases. The HA-binding site in RHAMM contains two closely spaced sequences of clustered basic amino acids, in an alpha-helical conformation. In the present communication, we test whether an alpha-helical conformation is required for effective peptide binding to HA, and competitive disruption of HA-RHAMM interaction. The HA-binding RHAMM-competitive peptide P15-1, identified using the unbiased approach of phage display, was examined using circular dichroism spectroscopy and the conformation-predictive AI-based AlphaFold2 algorithm. Unlike the HA-binding site in RHAMM, peptide P15-1 was found to adopt irregular conformations in solution rather than alpha helices. Instead, our structural analysis suggests that the primary determinant of peptide-HA binding is associated with a specific clustering and spacing pattern of basic amino acids, allowing favorable electrostatic interaction with carboxylate groups on HA.

CD44: a cancer stem cell marker and therapeutic target in leukemia treatment

CD44 is a ubiquitous leukocyte adhesion molecule involved in cell-cell interaction, cell adhesion, migration, homing and differentiation. CD44 can mediate the interaction between leukemic stem cells and the surrounding extracellular matrix, thereby inducing a cascade of signaling pathways to regulate their various behaviors. In this review, we focus on the impact of CD44s/CD44v as biomarkers in leukemia development and discuss the current research and prospects for CD44-related interventions in clinical application.

CD44 Expression in Clear Cell Renal Cell Carcinoma (ccRCC) Correlates with Tumor Grade and Patient Survival and Is Affected by Gene Methylation

Clear cell RCC (ccRCC) represents the most common type of kidney cancer, with surgery being the only potential curative treatment. Almost one-third of ccRCC patients relapse either locally or as cases of distant metastases. Several biomarkers have been employed in order to separate ccRCC patients with better prognosis or to predict treatment outcomes, with limited results. CD44 is a membrane glycoprotein with multiple roles in normal development but also cancer. Recently, the CD44 standard isoform has been implicated in tumor progression and the metastasis cascade through microenvironment interactions. Here, through CD44 immunohistochemical staining of ccRCC patient samples and TCGA data analysis, we sought to elucidate the expression patterns (mRNA and protein) of CD44 in clear cell RCC and correlate its expression with clinicopathological parameters. We were able to show that CD44 expression presents a positive association with tumor grade and overall survival, predicting a worse patient outcome in ccRCC. In addition, our data indicate that the CD44 mRNA upregulation can be attributed to reduced gene methylation, implicating epigenetic gene regulation in ccRCC development and progression.

The role of fibrosis in cardiomyopathies: An opportunity to develop novel biomarkers of disease activity

Cardiomyopathies encompass a spectrum of heart disorders with diverse causes and presentations. Fibrosis stands out as a shared hallmark among various cardiomyopathies, reflecting a common thread in their pathogenesis. This prevalent fibrotic response is intricately linked to the consequences of dysregulated extracellular matrix (ECM) remodeling, emphasizing its significance in the development and progression the disease. This review explores the ECM involvement in various cardiomyopathies and its impact on myocardial stiffness and fibrosis. Additionally, we discuss the potential of ECM fragments as early diagnosis, prognosis, and risk stratification. Biomarkers deriving from turnover of collagens and other ECM proteins hold promise in clinical applications. We outline current clinical management, future directions, and the potential for personalized ECM-targeted therapies with specific focus on microRNAs. In summary, this review examines the role of the fibrosis in cardiomyopathies, highlighting the potential of ECM-derived biomarkers in improving disease management with implications for precision medicine.

Extracellular vimentin as a versatile immune suppressive protein in cancer

The interest in finding new targets in the tumor microenvironment for anti-cancer therapy has increased rapidly over the years. More specifically, the tumor-associated blood vessels are a promising target. We recently found that the intermediate filament protein vimentin is externalized by endothelial cells of the tumor vasculature. Extracellular vimentin was shown to sustain angiogenesis by mimicking VEGF and supporting cell migration, as well as endothelial cell anergy, the unresponsiveness of the endothelium to proinflammatory cytokines. The latter hampers immune cell infiltration and subsequently provides escape from tumor immunity. Other studies showed that extracellular vimentin plays a role in sustained systemic and local inflammation. Here we will review the reported roles of extracellular vimentin with a particular emphasis on its involvement in the interactions between immune cells and the endothelium in the tumor microenvironment. To this end, we discuss the different ways by which extracellular vimentin modulates the immune system. Moreover, we review how this protein can alter immune cell-vessel wall adhesion by altering the expression of adhesion proteins, attenuating immune cell infiltration into the tumor parenchyma. Finally, we discuss how vimentin-targeting therapy can reverse endothelial cell anergy and promote immune infiltration, supporting anti-tumor immunity.

Delivering drugs to tubular cells and organelles: the application of nanodrugs in acute kidney injury

Acute kidney injury (AKI) is a common clinical syndrome with limited treatment options and high mortality rates. Proximal tubular epithelial cells (PTECs) play a key role in AKI progression. Subcellular dysfunctions, including mitochondrial, nuclear, endoplasmic reticulum and lysosomal dysfunctions, are extensively studied in PTECs. These studies have led to the development of potential therapeutic drugs. However, clinical development of those drugs faces challenges such as low solubility, short circulation time and severe systemic side effects. Nanotechnology provides a promising solution by improving drug properties through nanocrystallization and enabling targeted delivery to specific sites. This review summarizes advancements and limitations of nanoparticle-based drug-delivery systems in targeting PTECs and subcellular organelles, particularly mitochondria, for AKI treatment.

Weaving the nest: extracellular matrix roles in pre-metastatic niche formation

The discovery that primary tumors condition distant organ sites of future metastasis for seeding by disseminating tumor cells through a process described as the pre-metastatic niche (PMN) formation revolutionized our understanding of cancer progression and opened new avenues for therapeutic interventions. Given the inherent inefficiency of metastasis, PMN generation is crucial to ensure the survival of rare tumor cells in the otherwise hostile environments of metastatic organs. Early on, it was recognized that preparing the "soil" of the distal organ to support the outgrowth of metastatic cells is the initiating event in PMN development, achieved through the remodeling of the organ's extracellular matrix (ECM). Remote restructuring of ECM at future sites of metastasis under the influence of primary tumor-secreted factors is an iterative process orchestrated through the crosstalk between resident stromal cells, such as fibroblasts, epithelial and endothelial cells, and recruited innate immune cells. In this review, we will explore the ECM changes, cellular effectors, and the mechanisms of ECM remodeling throughout PMN progression, as well as its impact on shaping the PMN and ultimately promoting metastasis. Moreover, we highlight the clinical and translational implications of PMN ECM changes and opportunities for therapeutically targeting the ECM to hinder PMN formation.

Investigating Trans-differentiation of Glioblastoma Cells in an In Vitro 3D Model of the Perivascular Niche

Glioblastoma multiforme (GBM) is the deadliest form of brain cancer, responsible for over 50% of adult brain tumors. A specific region within the GBM environment is known as the perivascular niche (PVN). This area is defined as within approximately 100 μm of vasculature and plays an important role in the interactions between endothelial cells (ECs), astrocytes, GBM cells, and stem cells. We have designed a 3D in vitro model of the PVN comprising either collagen Type 1 or HyStem-C, human umbilical vein ECs (HUVECs), and LN229 (GBM) cells. HUVECs were encapsulated within the hydrogels to form vascular networks. After 7 days, LN229 cells were co-cultured to investigate changes in both cell types. Over a 14 day culture period, we measured alterations in HUVEC networks, the contraction of the hydrogels, trans-differentiation of LN229 cells, and the concentrations of two chemokines; CXCL12 and TGF-β. Increased cellular proliferation ranging from 10- to 16-fold was exhibited in co-cultures from days 8 to 14. This was accompanied with a decrease in the height of hydrogels of up to 68%. These changes in the biomaterial scaffold indicate that LN229-HUVEC interactions promote changes to the matrix. TGF-β and CXCL12 secretion increased approximately 2-2.6-fold each from day 8 to 14 in all co-cultures. The expression of CXCL12 correlated with cell colocalization, indicating a chemotactic role in enabling the migration of LN229 cells toward HUVECs in co-cultures. von Willebrand factor (vWF) was co-expressed with glial fibrillary acidic protein (GFAP) in up to 15% of LN229 cells after 24 h in co-culture. Additionally, when LN229 cells were co-cultured with human brain microvascular ECs, the percentages of GFAP⁺/vWF⁺ cells were up to 20% higher than that in co-cultures with HUVECs in collagen (2.2 mg/mL) and HyStem-C gels on day 14. The expression of vWF indicates the early stages of trans-differentiation of LN229 cells to an EC phenotype. Designing in vitro models of trans-differentiation may provide additional insights into how vasculature and cellular phenotypes are altered in GBM.

Fibroblast-targeting polymeric nanovehicles to enhance topical wound healing through promotion of PAR-2 receptor-mediated endocytosis

The level of collagen production critically determines skin wound contraction. If an intelligent skin drug delivery technology that enables collagen production in a specific wound skin area is developed, a breakthrough in wound healing treatment would be expected. However, such an intelligent drug delivery technology has not yet been developed as much as in the field of anticancer therapy. In this study, we propose a smart drug delivery system using polymeric nanovehicles (PNVs), in which the periphery is conjugated with a fibroblast-targeting collagen-derived peptide, KTTKS (Lys-Thr-Thr-Lys-Ser). We showed that surface engineering of PNVs with simultaneous PEGylation and peptide patching improved the dispersibility of PNVs, while promoting selective cellular uptake to fibroblasts via PAR-2 receptor-mediated endocytosis. In vitro collagen production and in vivo wound healing assays revealed that curcumin-loaded fibroblast-targeting PNVs significantly enhanced collagen production and wound healing activities, thus promising effective skin tissue regeneration.

HA-DOPE-Modified Honokiol-Loaded Liposomes Targeted Therapy for Osteosarcoma

Purpose

Osteosarcoma (OS) is the most common bone cancer with a high risk of metastasis, high growth rate, and poor prognosis. Honokiol (HNK) is a general ingredient of traditional Chinese medicine, with a potential anti-tumor effect. However, HNK is insoluble in water and lacks drug targeting, which limits its clinical application. To improve the OS therapeutic effect of HNK, we used HNK-loaded liposomes modified with hyaluronic acid-phospholipid conjugates (HA-DOPE) to treat OS based on the HA interaction with CD44.

Methods

The HNK-loaded liposomes were prepared via thin-film hydration and sonication. HA-DOPE was used to combine the HNK-loaded liposomes (HA-DOPE@Lips/HNK) via sonication and co-extrusion. HA-DOPE@Lips/HNK were characterized with respect to size, zeta potential, polymer dispersity index (PDI), and stability, and transmission electron microscopy was performed. Cellular uptake, cell viability, cell apoptosis, cell cycle, and mitochondrial activity were utilized to evaluate the antitumor effect in vitro. The biodistribution, xenograft tumor growth inhibition, and safety of HA-DOPE@Lips/HNK were evaluated in 143B OS xenograft mice in vivo.

Results

The particle size, PDI, and zeta potential of HA-DOPE@Lips/HNK were 146.20±0.26 nm, 0.20±0.01, and −38.45±0.98 mV, respectively. The encapsulation rate and drug loading were 80.14±0.32% and 3.78±0.09%, respectively. HA-DOPE@Lips/HNK could inhibit cell proliferation, cause apoptosis, block the cell cycle and disrupt mitochondrial activity. HA-DOPE@Lips/HNK specially delivered the drug into the tumor and inhibited tumor growth, and showed no obvious toxicity to normal tissues.

Conclusion

HA-DOPE@Lips/HNK could deliver HNK into the tumor site and had a good antitumor ability in vitro and in vivo. In addition, HA-DOPE@Lips/HNK increased the antitumor effects of HNK. Thus, it provides a promising nanocarrier to improve drug delivery in OS therapy.

Novel evaluation of the expression patterns CD44 and MMP9 proteins in intracranial meningiomas and their relationship to the overall survival

Background

Meningiomas are common primary brain neoplasms. CD44 is a cell surface glycoprotein receptor that is involved in matrix-mediated cell signaling and cell–matrix adhesion. Matrix metalloproteinase-9 (MMP-9) plays important role in angiogenesis and tumor invasion. The expression of CD44 protein membranous and cytoplasmic (CD44M and CD44C) has been reported in several tumors (such as lobular carcinoma, renal cell carcinoma, sinonasal melanoma, and lymphoma) except CNS tumors.

Methods

This study addressed the expression of CD44M and CD44C and MMP9 proteins in intracranial meningiomas and their relationship to overall survival. The expression patterns of CD44M&C and MMP-9 proteins were examined in 32 cases of benign meningiomas, 12 cases of atypical meningiomas, and 6 cases of anaplastic meningiomas using immunohistochemical staining methods.

Results

There was more evidence of CD44M expression in atypical and anaplastic meningioma (p =  < 0.001). Interestingly, Spearman correlation analyses revealed significant positive correlation between CD44M and MMP9 protein (r = 0.572, p =  < 0.001) in spite of the negative correlation between MMP9 and CD44 score (r = − 0.035 p = 0.405). There was a significant association between Ki67 protein expression and the grade of meningiomas (p < 0.001) and gender (p = 0.026). There was a significant correlation between overall survival (OS) and age, gender, tumor grade, and Ki-67.

Conclusions

Extensive CD44M expression in high-grade meningioma may reflect a tendency toward more invasive power of meningioma cells into surrounding structures (dura, bone, and brain).CD44M/MMP-9 axis presented by this study is open for future investigations.

Hyaluronic Acid-Based Nanomaterials Applied to Cancer: Where Are We Now?

Cancer cells normally develop the ability to rewire or reprogram themselves to become resistant to treatments that were previously effective. Despite progress in understanding drug resistance, knowledge gaps remain regarding the underlying biological causes of drug resistance and the design of cancer treatments to overcome it. So, resistance acquisition remains a major problem in cancer treatment. Targeted therapeutics are considered the next generation of cancer therapy because they overcome many limitations of traditional treatments. Numerous tumor cells overexpress several receptors that have a high binding affinity for hyaluronic acid (HA), while they are poorly expressed in normal body cells. HA and its derivatives have the advantage of being biocompatible and biodegradable and may be conjugated with a variety of drugs and drug carriers for developing various formulations as anticancer therapies such as micelles, nanogels, and inorganic nanoparticles. Due to their stability in blood circulation and predictable delivery patterns, enhanced tumor-selective drug accumulation, and decreased toxicity to normal tissues, tumor-targeting nanomaterial-based drug delivery systems have been shown to represent an efficacious approach for the treatment of cancer. In this review, we aim to provide an overview of some in vitro and in vivo studies related to the potential of HA as a ligand to develop targeted nanovehicles for future biomedical applications in cancer treatment.

Proteolytic modulation of tumor microenvironment signals during cancer progression

Under normal conditions, the cellular microenvironment is optimized for the proper functioning of the tissues and organs. Cells recognize and communicate with the surrounding cells and extracellular matrix to maintain homeostasis. When cancer arises, the cellular microenvironment is modified to optimize its malignant growth, evading the host immune system and finding ways to invade and metastasize to other organs. One means is a proteolytic modification of the microenvironment and the signaling molecules. It is now well accepted that cancer progression relies on not only the performance of cancer cells but also the surrounding microenvironment. This mini-review discusses the current understanding of the proteolytic modification of the microenvironment signals during cancer progression.

Cisplatin-Chelated Iminodiacetic Acid-Conjugated Hyaluronic Acid Nanogels for the Treatment of Malignant Pleural Mesothelioma in Mice

Malignant pleural mesothelioma (MPM) is one of the intractable cancers that require a more effective therapeutic strategy for clinical practice. Hyaluronic acid (HA) nanogels were prepared by the chelation of cisplatin (CDDP) with different molecular weights of iminodiacetic acid-conjugated hyaluronic acid (HA-IDA). The sizes of the 100, 850, and 2000 kDa HA nanogels were 33, 43, and 44 nm, respectively. MSTO-211H, a human MPM cell line, was more effective in taking up all three HA nanogels compared to AB22, a mouse MPM cell line. In addition, the 850 kDa HA nanogel showed higher anticancer activity against AB22 and MSTO-211H than 100 and 2000 kDa HA nanogels. Furthermore, all the HA nanogels showed a milder cytotoxic effect on normal Met-5A mesothelial cells compared to that exhibited by free CDDP. Finally, the 850 kDa HA nanogel was administrated intrapleurally into both the MSTO-211H xenograft and AB22 allograft mouse models of MPM using an injectable HA-based hydrogel. HA nanogels showed a significant therapeutic effect in both the xenograft and allograft models.

Pathogenesis of glaucoma: Extracellular matrix dysfunction in the trabecular meshwork-A review

The trabecular meshwork regulates aqueous humour outflow from the anterior chamber of the eye. It does this by establishing a tunable outflow resistance, defined by the interplay between cells and their extracellular matrix (ECM) milieu, and the molecular interactions between ECM proteins. During normal tissue homeostasis, the ECM is remodelled and trabecular cell behaviour is modified, permitting increased aqueous fluid outflow to maintain intraocular pressure (IOP) within a relatively narrow physiological pressure. Dysfunction in the normal homeostatic process leads to increased outflow resistance and elevated IOP, which is a primary risk factor for glaucoma. This review delineates some of the changes in the ECM that lead to gross as well as some more subtle changes in the structure and function of the ECM, and their impact on trabecular cell behaviour. These changes are discussed in the context of outflow resistance and glaucoma.

Modulation of Microenvironment Signals by Proteolytic Shedding of Cell Surface Extracellular Matrix Receptors

Multicellular organisms are composed of cells and extracellular matrix (ECM). ECM is a network of multidomain macromolecules that fills gaps between cells. It acts as a glue to connect cells, provides scaffolding for migrating cells, and pools cytokines and growth factors. ECM also directly sends signals to the cells through ECM receptors, providing survival signals and migration cues. Altogether, ECM provides a correct microenvironment for the cells to function in the tissue. Although ECM acts as a signaling molecule, they are insoluble solid molecules, unlike soluble receptor ligands such as cytokines and growth factors. Upon cell binding to the ECM through ECM receptors and signals transmitted, cells then need to have a mechanism to release from ECM to prevent prolonged signals, which may be tumorigenic, and migrate on ECM. One effective means to release the cells from ECM is to cleave the ECM receptors by proteinases. In this mini-review, current knowledge of ECM receptor shedding will be discussed.

MCT1 expression is independently related to shorter cancer-specific survival in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) has been considered a metabolic disease, with loss of von Hippel-Lindau (VHL) gene and consequent overexpression of hypoxia-inducible factor 1 alpha (HIF-1α), which is central for tumor development and progression. Among other effects, HIF-1α is involved in the metabolic reprogramming of cancer cells towards the Warburg effect involved in tumor cell proliferation, migration and survival. In this context, several proteins are expressed by cancer cells, including glucose and lactate transporters as well as different pH regulators. Among them, monocarboxylate transporters (MCTs) can be highlighted. Our aim is to comprehensively analyze the immunoexpression of MCT1, MCT2, MCT4, CD147, CD44, HIF-1α, GLUT1 and CAIX in ccRCC surgical specimens correlating with classical prognostic factors and survival of patients with long follow up. Surgical specimens from 207 patients with ccRCC who underwent radical or partial nephrectomy were used to build a tissue microarray. Immunostaining was categorized into absent/weak or moderate/strong and related to all classic ccRCC prognostic parameters. Kaplan-Meier curves were generated to assess overall and cancer-specific survival, and multivariate analysis was performed to identify independent prognostic factors of survival. Multivariate analysis showed that MCT1 together with tumor size and TNM staging, were independently related to cancer-specific survival. MCT1, CD147, CD44 and GLUT1 expression were significantly associated with poor prognostic factors. We show that MCT1 is an independent prognostic factor for cancer-specific survival in ccRCC justifying the use of new target therapies already being tested in clinical trials.

Interplay between extracellular matrix components and cellular and molecular mechanisms in kidney fibrosis

Chronic kidney disease (CKD) is characterized by pathological accumulation of extracellular matrix (ECM) proteins in renal structures. Tubulointerstitial fibrosis is observed in glomerular diseases as well as in the regeneration failure of acute kidney injury (AKI). Therefore, finding antifibrotic therapies comprises an intensive research field in Nephrology. Nowadays, ECM is not only considered as a cellular scaffold, but also exerts important cellular functions. In this review, we describe the cellular and molecular mechanisms involved in kidney fibrosis, paying particular attention to ECM components, profibrotic factors and cell-matrix interactions. In response to kidney damage, activation of glomerular and/or tubular cells may induce aberrant phenotypes characterized by overproduction of proinflammatory and profibrotic factors, and thus contribute to CKD progression. Among ECM components, matricellular proteins can regulate cell-ECM interactions, as well as cellular phenotype changes. Regarding kidney fibrosis, one of the most studied matricellular proteins is cellular communication network-2 (CCN2), also called connective tissue growth factor (CTGF), currently considered as a fibrotic marker and a potential therapeutic target. Integrins connect the ECM proteins to the actin cytoskeleton and several downstream signaling pathways that enable cells to respond to external stimuli in a coordinated manner and maintain optimal tissue stiffness. In kidney fibrosis, there is an increase in ECM deposition, lower ECM degradation and ECM proteins cross-linking, leading to an alteration in the tissue mechanical properties and their responses to injurious stimuli. A better understanding of these complex cellular and molecular events could help us to improve the antifibrotic therapies for CKD.

A CD44/Brg1 nuclear complex confers mesenchymal progenitor cells with enhanced fibrogenicity in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease. We previously identified fibrogenic mesenchymal progenitor cells (MPCs) in the lungs of patients with IPF who serve as drivers of progressive fibrosis. Recent single-cell RNA sequencing work revealed that IPF MPCs with the highest transcriptomic network entropy differ the most from control MPCs and that increased CD44 was a marker of these IPF MPCs. We hypothesize that IPF MPCs with high CD44 (CD44^hi) expression will display enhanced fibrogenicity. We demonstrate that CD44-expressing MPCs are present at the periphery of the IPF fibroblastic focus, placing them in regions of active fibrogenesis. In a humanized mouse xenograft model, CD44^hi IPF MPCs are more fibrogenic than CD44^lo IPF MPCs, and knockdown of CD44 diminishes their fibrogenicity. CD44^hi IPF MPCs display increased expression of pluripotency markers and enhanced self-renewal compared with CD44^lo IPF MPCs, properties potentiated by IL-8. The mechanism involves the accumulation of CD44 within the nucleus, where it associates with the chromatin modulator protein Brahma-related gene 1 (Brg1) and the zinc finger E-box binding homeobox 1 (Zeb1) transcription factor. This CD44/Brg1/Zeb1 nuclear protein complex targets the Sox2 gene, promoting its upregulation and self-renewal. Our data implicate CD44 interaction with the epigenetic modulator protein Brg1 in conveying IPF MPCs with cell-autonomous fibrogenicity.

The role of CD44 in cancer chemoresistance: A concise review

CD44 is a cell surface adhesion molecule, which is overexpressed on cancer stem cells. The interaction of CD44 with hyaluronan is responsible for tumor development, metastasis, and expression of the chemoresistant phenotype. The overexpression of CD44 impedes the cytotoxic effect of chemotherapy medications in various cancers. Therefore, the high expression of CD44 is associated with a poor prognosis in affected patients. This high expression of CD44 in various cancers has provided an ample opportunity for the treatment of patients with chemoresistant malignancy. This review aims to demonstrate the various cross-talk between CD44 and intracellular and extracellular factors and highlight its role in developing chemoresistant tumors in some troublesome cancers.

Immuno-Electron and Confocal Laser Scanning Microscopy of the Glycocalyx

Simple Summary

The glycocalyx (GCX) is a hydrated, gel-like layer of biological macromolecules attached to the cell membrane. The GCX acts as a barrier and regulates the entry of external substances into the cell. The function of the GCX is highly dependent on its structure and composition. Pathogenic factors can affect the protective structure of the GCX. We know very little about the three-dimensional organization of the GXC. The tiny and delicate structures of the GCX are difficult to study by microscopic techniques. In this study, we evaluated a method to preserve and label sensitive GCX components with antibodies for high-resolution microscopy analysis. High-resolution microscopy is a powerful tool because it allows visualization of ultra-small components and biological interactions. Our method can be used as a tool to better understand the role of the GCX during the development and progression of diseases, such as viral infections, tumor invasion, and the development of atherosclerosis.

Abstract

The glycocalyx (GCX), a pericellular carbohydrate rich hydrogel, forms a selective barrier that shields the cellular membrane, provides mechanical support, and regulates the transport and diffusion of molecules. The GCX is a fragile structure, making it difficult to study by transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Sample preparation by conventional chemical fixation destroys the GCX, giving a false impression of its organization. An additional challenge is to process the GCX in a way that preserves its morphology and enhanced antigenicity to study its cell-specific composition. The aim of this study was to provide a protocol to preserve both antigen accessibility and the unique morphology of the GCX. We established a combined high pressure freezing (HPF), osmium-free freeze substitution (FS), rehydration, and pre-embedding immunogold labeling method for TEM. Our results showed specific immunogold labeling of GCX components expressed in human monocytic THP-1 cells, hyaluronic acid receptor (CD44) and chondroitin sulfate (CS), and maintained a well-preserved GCX morphology. We adapted the protocol for antigen localization by CLSM and confirmed the specific distribution pattern of GCX components. The presented combination of HPF, FS, rehydration, and immunolabeling for both TEM and CLSM offers the possibility for analyzing the morphology and composition of the unique GCX structure.

CD44 and Tumor-Derived Extracellular Vesicles (TEVs). Possible Gateway to Cancer Metastasis

Cancer metastasis, the final stage of tumor progression, is a complex process governed by the interplay of multiple types of cells and the tumor microenvironment. One of the aspects of this interplay involves the release of various factors by the tumor cells alone or by forcing other cells to do so. As a consequence of these actions, tumor cells are prepared in favorable conditions for their dissemination and spread to other sites/organs, which guarantees their escape from immunosurveillance and further progression. Tumor-derived extracellular vesicles (TEVs) represent a heterogeneous population of membrane-bound vesicles that are being actively released by different tumors. The array of proteins (i.e., receptors, cytokines, chemokines, etc.) and nucleic acids (i.e., mRNA, miR, etc.) that TEVs can transfer to other cells is often considered beneficial for the tumor’s survival and proliferation. One of the proteins that is associated with many different tumors as well as their TEVs is a cluster of differentiation 44 in its standard (CD44s) and variant (CD44v) form. This review covers the present information regarding the TEVs-mediated CD44s/CD44v transfer/interaction in the context of cancer metastasis. The content and the impact of the transferred cargo by this type of TEVs also are discussed with regards to tumor cell dissemination.

Proteolytic Processing of CD44 and Its Implications in Cancer

CD44 is a transmembrane glycoprotein expressed in several healthy and tumor tissues. Modifications in its structure contribute differently to the activity of this molecule. One modification that has provoked interest is the consecutive cleavage of the CD44 extracellular ectodomain by enzymes that belong mainly to the family of metalloproteases. This process releases biologically active substrates, via alternative splice forms of CD44, that generate CD44v3 or v6 isoforms which participate in the transcriptional regulation of genes and proteins associated to signaling pathways involved in the development of cancer. These include the protooncogene tyrosine-protein kinase Src (c-Src)/signal transducer and activator of transcription 3 (STAT3), the epithelial growth factor receptor, the estrogen receptor, Wnt/βcatenin, or Hippo signaling pathways all of which are associated to cell proliferation, differentiation, or cancer progression. Whereas CD44 still remains as a very useful prognostic cell marker in different pathologies, the main topic is that the generation of CD44 intracellular fragments assists the regulation of transcriptional proteins involved in the cell cycle, cell metabolism, and most importantly, the regulation of some stem cell-associated markers.

Cardiac ECM: Its Epigenetic Regulation and Role in Heart Development and Repair

The extracellular matrix (ECM) is the non-cellular component in the cardiac microenvironment, and serves essential structural and regulatory roles in establishing and maintaining tissue architecture and cellular function. The patterns of molecular and biochemical ECM alterations in developing and adult hearts depend on the underlying injury type. In addition to exploring how the ECM regulates heart structure and function in heart development and repair, this review conducts an inclusive discussion of recent developments in the role, function, and epigenetic guidelines of the ECM. Moreover, it contributes to the development of new therapeutics for cardiovascular disease.

Cell-surface heparan sulfate proteoglycans as multifunctional integrators of signaling in cancer

Proteoglycans (PGs) represent a large proportion of the components that constitute the extracellular matrix (ECM). They are a diverse group of glycoproteins characterized by a covalent link to a specific glycosaminoglycan type. As part of the ECM, heparan sulfate (HS)PGs participate in both physiological and pathological processes including cell recruitment during inflammation and the promotion of cell proliferation, adhesion and motility during development, angiogenesis, wound repair and tumor progression. A key function of HSPGs is their ability to modulate the expression and function of cytokines, chemokines, growth factors, morphogens, and adhesion molecules. This is due to their capacity to act as ligands or co-receptors for various signal-transducing receptors, affecting pathways such as FGF, VEGF, chemokines, integrins, Wnt, notch, IL-6/JAK-STAT3, and NF-κB. The activation of those pathways has been implicated in the induction, progression, and malignancy of a tumor. For many years, the study of signaling has allowed for designing specific drugs targeting these pathways for cancer treatment, with very positive results. Likewise, HSPGs have become the subject of cancer research and are increasingly recognized as important therapeutic targets. Although they have been studied in a variety of preclinical and experimental models, their mechanism of action in malignancy still needs to be more clearly defined. In this review, we discuss the role of cell-surface HSPGs as pleiotropic modulators of signaling in cancer and identify them as promising markers and targets for cancer treatment.

Resident CD34-positive cells contribute to peri-endothelial cells and vascular morphogenesis in salivary gland after irradiation

Salivary gland (SG) hypofunction is a common post-radiotherapy complication. Besides the parenchymal damage after irradiation (IR), there are also effects on mesenchymal stem cells (MSCs) which were shown to contribute to regeneration and repair of damaged tissues by differentiating into stromal cell types or releasing vesicles and soluble factors supporting the healing processes. However, there are no adequate reports about their roles during SG damage and regeneration so far. Using an irradiated SG mouse model, we performed certain immunostainings on tissue sections of submandibular glands at different time points after IR. Immunostaining for CD31 revealed that already one day after IR, vascular impairment was induced at the level of capillaries. In addition, the expression of CD44—a marker of acinar cells—diminished gradually after IR and, by 20 weeks, almost disappeared. In contrast, the number of CD34-positive cells significantly increased 4 weeks after IR and some of the CD34-positive cells were found to reside within the adventitia of arteries and veins. Laser confocal microscopic analyses revealed an accumulation of CD34-positive cells within the area of damaged capillaries where they were in close contact to the CD31-positive endothelial cells. At 4 weeks after IR, a fraction of the CD34-positive cells underwent differentiation into α-SMA-positive cells, which suggests that they may contribute to regeneration of smooth muscle cells and/or pericytes covering the small vessels from the outside. In conclusion, SG-resident CD34-positive cells represent a population of progenitors that could contribute to new vessel formation and/or remodeling of the pre-existing vessels after IR and thus, might be an important player during SG tissue healing.

Role of CD44 in breast cancer

Breast cancer (BC) is among the most prevalent type of malignancy affecting females worldwide. BC is classified into different types according to the status of the expression of receptors such as estrogen receptor (ER), human epidermal growth factor receptor 2 (HER2), and progesterone receptor (PR). Androgen receptor (AR) appears to be a promising therapeutic target of BC. Binding of 5α-dihydrotestosterone (DHT) to AR controls the expression of microRNA (miRNA) molecules in BC, consequently, affecting protein expression. One of these proteins is the transmembrane glycoprotein cluster of differentiation 44 (CD44). Remarkably, CD44 is a common marker of cancer stem cells in BC. It functions as a co-receptor for a broad diversity of extracellular matrix ligands. Several ligands, primarily hyaluronic acid (HA), can interact with CD44 and mediate its functions. CD44 promotes a variety of functions independently or in cooperation with other cell-surface receptors through activation of varied signaling pathways like Rho GTPases, Ras-MAPK, and PI3K/AKT pathways to regulate cell adhesion, migration, survival, invasion, and epithelial-mesenchymal transition. In this review, we present the relations between AR, miRNA, and CD44 and their roles in BC.

The Role of Proteoglycans in Cancer Metastasis and Circulating Tumor Cell Analysis

Circulating tumor cells (CTCs) are accessible by liquid biopsies via an easy blood draw. They represent not only the primary tumor site, but also potential metastatic lesions, and could thus be an attractive supplement for cancer diagnostics. However, the analysis of rare CTCs in billions of normal blood cells is still technically challenging and novel specific CTC markers are needed. The formation of metastasis is a complex process supported by numerous molecular alterations, and thus novel CTC markers might be found by focusing on this process. One example of this is specific changes in the cancer cell glycocalyx, which is a network on the cell surface composed of carbohydrate structures. Proteoglycans are important glycocalyx components and consist of a protein core and covalently attached long glycosaminoglycan chains. A few CTC assays have already utilized proteoglycans for both enrichment and analysis of CTCs. Nonetheless, the biological function of proteoglycans on clinical CTCs has not been studied in detail so far. Therefore, the present review describes proteoglycan functions during the metastatic cascade to highlight their importance to CTCs. We also outline current approaches for CTC assays based on targeting proteoglycans by their protein cores or their glycosaminoglycan chains. Lastly, we briefly discuss important technical aspects, which should be considered for studying proteoglycans.

Identification of sequence-specific interactions of the CD44-intracellular domain with RUNX2 in the transcription of matrix metalloprotease-9 in human prostate cancer cells

Aim

The Cluster of differentiation 44 (CD44) transmembrane protein is cleaved by γ-secretase, the inhibition of which blocks CD44 cleavage. This study aimed to determine the biological consequence of CD44 cleavage and its potential interaction with Runt-related transcription factor (RUNX2) in a sequence-specific manner in PC3 prostate cancer cells.

Methods

Using full-length and C-terminal deletion constructs of CD44-ICD (D1-D5) expressed as stable green fluorescent protein-fusion proteins in PC3 cells, we located possible RUNX2-binding sequences.

Results

Chromatin immunoprecipitation assays demonstrated that the C-terminal amino acid residues between amino acids 671 and 706 in D1 to D3 constructs were indispensable for sequence-specific binding of RUNX2. This binding was minimal for sequences in the D4 and D5 constructs. Correspondingly, an increase in matrix metalloprotease-9 (MMP-9) expression was observed at the mRNA and protein levels in PC3 cells stably expressing D1-D3 constructs.

Conclusion

These results provide biochemical evidence for the possible sequence-specific CD44-ICD/RUNX2 interaction and its functional relationship to MMP-9 transcription in the promoter region.

The peridural membrane of the spine has characteristics of synovium

The peridural membrane (PDM) is a well-defined structure between dura mater and the wall of the spinal canal. The spine may be viewed as a multi-segmented joint, with the epidural cavity and neural foramina as joint spaces and PDM as synovial lining. The objective of this investigation was to determine if PDM has histological characteristics of synovium. Samples of the PDM of the thoraco-lumbar spine were taken from 23 human cadavers and analyzed with conventional light microscopy and confocal microscopy. Results were compared to reports on similar analyses of synovium in the literature. Histological distribution of areolar, fibrous, and adipose connective tissue in PDM was similar to synovium. The PDM has an intima and sub-intima. No basement membrane was identified. CD68, a marker for macrophage-like-synoviocytes, and CD55, a marker for fibroblast-like synoviocytes, were seen in the lining and sub-lining of the PDM. Multifunctional hyaluronan receptor CD44 and hyaluronic acid synthetase 2 marker HAS2 were abundantly present throughout the membrane. Marked presence of CD44, CD55, and HAS2 in the well-developed tunica muscularis of blood vessels and in the body of the PDM suggests a role in the maintenance and lubrication of the epidural cavity and neural foramina. Presence of CD68, CD55, and CD44 suggests a scavenging function and a role in the inflammatory response to noxious stimuli. Thus, the human PDM has histological and immunohistochemical characteristics of synovium. This suggests that the PDM may be important for the homeostasis of the flexible spine and the neural structures it contains.

Anticancer activities of phytoconstituents and their liposomal targeting strategies against tumor cells and the microenvironment

Various bioactive ingredients have been extracted from Chinese herbal medicines (CHMs) that affect tumor progression and metastasis. To further understand the mechanisms of CHMs in cancer therapy, this article summarizes the effects of five categories of CHMs and their active ingredients on tumor cells and the tumor microenvironment. Despite their treatment potential, the undesirable physicochemical properties (poor permeability, instability, high hydrophilicity or hydrophobicity, toxicity) and unwanted pharmacokinetic profiles (short half-life in blood and low bioavailability) restrict clinical studies of CHMs. Therefore, development of liposomes through relevant surface modifying techniques to achieve targeted CHM delivery for cancer cells, i.e., extracellular and intracellular targets and targets in tumor microenvironment or vasculature, have been reviewed. Current challenges of liposomal targeting of these phytoconstituents and future perspective of CHM applications are discussed to provide an informative reference for interested readers.

Hyaluronic Acid-Based Theranostic Nanomedicines for Targeted Cancer Therapy

Hyaluronic acid (HA) is a natural mucopolysaccharide and has many useful advantages, including biocompatibility, non-immunogenicity, chemical versatility, non-toxicity, biodegradability, and high hydrophilicity. Numerous tumor cells overexpress several receptors that have a high binding affinity for HA, while these receptors are poorly expressed in normal body cells. HA-based drug delivery carriers can offer improved solubility and stability of anticancer drugs in biological environments and allow for the targeting of cancer treatments. Based on these benefits, HA has been widely investigated as a promising material for developing the advanced clinical cancer therapies in various formulations, including nanoparticles, micelles, liposomes, and hydrogels, combined with other materials. We describe various approaches and findings showing the feasibility of improvement in theragnosis probes through the application of HA.

Biphasic MIF and SDF1 expression during podocyte injury promote CD44-mediated glomerular parietal cell migration in focal segmental glomerulosclerosis

Glomerular parietal epithelial cell (PEC) activation, as revealed by de novo expression of CD44 and cell migration toward the injured filtration barrier, is a hallmark of podocyte injury-driven focal segmental glomerulosclerosis (FSGS). However, the signaling pathway that mediates activation of PECs in response to podocyte injury is unknown. The present study focused on CD44 signaling, particularly the roles of two CD44-related chemokines, migration inhibitory factor (MIF) and stromal cell-derived factor 1 (SDF1), and their common receptor, chemokine (C-X-C motif) receptor 4 (CXCR4), in the NEP25/LMB2 mouse podocyte-toxin model of FSGS. In the early phase of the disease, CD44-positive PECs were locally evident on the opposite side of the intact glomerular tuft and subsequently increased in the vicinity of synechiae with podocyte loss. Expression of MIF and SDF1 was first increased in injured podocytes and subsequently transferred to activated PECs expressing CD44 and CXCR4. In an immortalized mouse PEC (mPEC) line, recombinant MIF and SDF1 (rMIF and rSDF1, respectively) individually increased CD44 and CXCR4 mRNA and protein levels. rMIF and rSDF1 stimulated endogenous MIF and SDF1 production. rMIF- and rSDF1-induced mPEC migration was suppressed by CD44 siRNA. However, MIF and SDF1 inhibitors failed to show any impact on proteinuria, podocyte number, and CD44 expression in NEP25/LMB2 mice. Our data suggest that injured podocytes upregulate MIF and SDF1 that stimulate CD44 expression and CD44-mediated migration, which is enhanced by endogenous MIF and SDF1 in PECs. This biphasic expression pattern of the chemokine-CD44 axis in podocytes and PECs may be a novel mechanism of "podocyte-PEC cross-talk" signaling underlying podocyte injury-driven FSGS.

Targeted Drug Delivery via the Use of ECM-Mimetic Materials

The use of drug delivery vehicles to improve the efficacy of drugs and to target their action at effective concentrations over desired periods of time has been an active topic of research and clinical investigation for decades. Both synthetic and natural drug delivery materials have facilitated locally controlled as well as targeted drug delivery. Extracellular matrix (ECM) molecules have generated widespread interest as drug delivery materials owing to the various biological functions of ECM. Hydrogels created using ECM molecules can provide not only biochemical and structural support to cells, but also spatial and temporal control over the release of therapeutic agents, including small molecules, biomacromolecules, and cells. In addition, the modification of drug delivery carriers with ECM fragments used as cell-binding ligands has facilitated cell-targeted delivery and improved the therapeutic efficiency of drugs through interaction with highly expressed cellular receptors for ECM. The combination of ECM-derived hydrogels and ECM-derived ligand approaches shows synergistic effects, leading to a great promise for the delivery of intracellular drugs, which require specific endocytic pathways for maximal effectiveness. In this review, we provide an overview of cellular receptors that interact with ECM molecules and discuss examples of selected ECM components that have been applied for drug delivery in both local and systemic platforms. Finally, we highlight the potential impacts of utilizing the interaction between ECM components and cellular receptors for intracellular delivery, particularly in tissue regeneration applications.

Dual Loading of Nanoparticles with Doxorubicin and Icotinib for the Synergistic Suppression of Non-Small Cell Lung Cancer

Background: Combination chemotherapy plays an important role in the clinical therapy of non-small cell lung cancer (NSCLC). However, the pharmacokinetic differences between drugs are an insurmountable barrier in traditional treatment. For the synergistic therapy of NSCLC, synergistic nanoparticles (EDS NPs) loaded with both an EGFR inhibitor and doxorubicin (DOX) were designed and prepared. Methods: Erlotinib, apatinib and icotinib were evaluated for optimal combination with DOX in treatment of NSCLC via CCK-8 assay. Then the cationic amphipathic starch (CSaSt) and hyaluronic acid (HA) were applied to coencapsulate DOX and EGFR inhibitor to form the EDS NPs. EDS NPs were evaluated in NSCLC cell lines (A549, NCI-H1975 and PC9) and NSCLC xenograft mouse models. Results: Icotinib was found to be the optimal synergistic drug in combination with DOX in the tested. Subsequently, icotinib and DOX were coencapsulated in the NPs. EDS NPs were roughly spherical with an average size of 65.7±6.2 nm and possessed stable loading and releasing properties. In the in vitro investigation, EDS NPs could efficiently deliver payloads into cells, exhibited cytotoxicity and produced strong anti-migration properties. In vivo hypotoxicity was confirmed by acute toxicity and hemolytic assays. The in vivo distribution showed that EDS NPs could enhance accumulation in tumors and decrease nonspecific accumulation in normal organs. EDS NPs significantly promoted the in vivo synergistic effects of icotinib and DOX in the mouse model. Conclusions: The study suggests that EDS NPs possess noteworthy potential for development as therapeutics for NSCLC clinical chemotherapy.

Docetaxel and Doxorubicin Codelivery by Nanocarriers for Synergistic Treatment of Prostate Cancer

Combination chemotherapy has been proven to be an efficient strategy for the treatment of prostate cancer (PCA). However, the pharmacokinetic distinction between the relevant drugs is an insurmountable barrier to the realization of their synergistic use against cancer. To overcome the disadvantages of combination chemotherapy in the treatment of PCA, targeted nanoparticles (NPs), which can codeliver docetaxel (DOC) and doxorubicin (DOX) at optimal synergistic proportions, have been designed. In this study, the DOC and DOX codelivery nanoparticles (DDC NPs) were constructed by hyaluronic acid (HA) and cationic amphipathic starch (CSaSt) through a self-assembly process. Human PCA cell lines (PC-3, DU-145, and LNCap) and mouse models were then used for evaluation in vitro and in vivo, respectively, of delivery and antitumor effects. The DDC NPs were spherical with rough surfaces, and the size and zeta potential were 68.4 ± 7.1 nm and -22.8 ± 2.2 mV, respectively. The encapsulation efficiencies of DOC and DOX in the NPs were 96.1 ± 2.3% and 91.4 ± 3.7%, respectively, while the total drug loading was 9.1 ± 1.7%. Moreover, the ratio of DOC to DOX in the DDC NPs was approximately 1:400, which aligned with the optimal synergistic proportions of the drugs. The DDC NPs exhibited excellent loading capacities, performed sustained and enzymatic release, and were stable in PBS, medium, and serum. After investigations in vitro, the DDC NPs were as effective as the dual drug combination in terms of cytotoxicity, antimigration, and apoptosis. Internalization results indicated that the DDC NPs could effectively deliver and fully release the payloads into PCA cells, and the process was mediated by the ligand-receptor interaction of HA with the CD44 protein. Low toxicity in vivo was confirmed by acute toxicity and hemolytic assays. The distribution in vivo showed that DDC NPs could enhance the accumulation of drugs in tumors and decrease nonspecific accumulation in normal organs. More importantly, DDC NPs significantly promoted the curative effect of the DOC and DOX combination in the PCA cell xenograft mouse model, indicating that the drugs with NPs did indeed act synergistically. This study suggests that the DDC NPs possess noteworthy potential as prospects for the development of PCA clinical chemotherapy.

Binding and Internalization in Receptor-Targeted Carriers: The Complex Role of CD44 in the Uptake of Hyaluronic Acid-Based Nanoparticles (siRNA Delivery)

CD44 is an endocytic hyaluronic acid (HA) receptor, and is overexpressed in many carcinomas. This has encouraged the use of HA to design CD44-targeting carriers. This paper is about dissecting the mechanistic role of CD44. Here, HA-decorated nanoparticles are used to deliver siRNA to both tumoral (AsPC-1, PANC-1, HT-29, HCT-116) and non-tumoral (fibroblasts, differently polarized THP-1 macrophages, HUVEC) human cell lines, evaluating the initial binding of the nanoparticles, their internalization rate, and the silencing efficiency (cyclophilin B (PPIB) gene). Tumoral cells internalize faster and experience higher silencing than non-tumoral cells. This is promising as it suggests that, in a tumor, HA nanocarriers may have limited off-target effects. More far-reaching is the inter-relation between the four parameters of the study: CD44 expression, HA binding on cell surfaces, internalization rate, and silencing efficiency. No correlation is found between binding (an early event) and any of the other parameters, whereas silencing correlates both with speed of the internalization process and CD44 expression. This study confirms on one hand that HA-based carriers can perform a targeted action, but on the other it suggests that this may not be due to a selective binding event, but rather to a later recognition leading to selective internalization.

Involvement of hyaluronan and CD44 in cancer and viral infections

Hyaluronan and its major receptor CD44 are ubiquitously distributed. They have important structural as well as signaling roles, regulating tissue homeostasis, and their expression levels are tightly regulated. In addition to signaling initiated by the interaction of the intracellular domain of CD44 with cytoplasmic signaling molecules, CD44 has important roles as a co-receptor for different types of receptors of growth factors and cytokines. Dysregulation of hyaluronan-CD44 interactions is seen in diseases, such as inflammation and cancer. In the present communication, we discuss the mechanism of hyaluronan-induced signaling via CD44, as well as the involvement of hyaluronan-engaged CD44 in malignancies and in viral infections.

Characterization of CD44 intracellular domain interaction with RUNX2 in PC3 human prostate cancer cells

BACKGROUND

Expression of CD44 receptor is associated with the onset of several tumors. The intracellular domain of CD44 (CD44-ICD) has been implicated as a co-transcription factor for RUNX2 in the regulation of expression of MMP-9 in breast carcinoma cells. Previous studies from our laboratory demonstrated the role of CD44 in migration and invasion of PC3 prostate cells through activation of MMP-9. CD44 signaling regulates the phosphorylation and hence the localization of RUNX2 in the nucleus. The role of CD44-ICD has not been studied in prostate cancer cells. This study aimed to explore the role of CD44-ICD and RUNX2 in the regulation of expression of metastasis-related genes.

METHODS

PC3 and PC3 cells overexpressing RUNX2 protein were analyzed for RUNX2/CD44-ICD interaction by immunoprecipitation, immunoblotting, and Immunofluorescence analyses. Wound healing and tumorsphere formation analyses were also done in these cells. The real-time PCR analysis was used to detect the expression levels of different genes.

RESULTS

Expression of CD44 and RUNX2 was observed only in PC3 cells (androgen receptor positive) and not in LNCaP or PCa2b cells (androgen receptor negative). Therefore, CD44-ICD fragment (~ 15-16 kDa) was observed in PC3 cells. Moreover, localization of CD44-ICD was more in the nucleus than in the cytoplasm of PC3 cells. Inhibition of cleavage of CD44 with a γ-secretase inhibitor, DAPT reduced the formation of CD44-ICD; however, accumulation of CD44-external truncation fragments (~ 20 and ~ 25 kDa) was detected. RUNX2 and CD44-ICD interact in the nucleus of PC3 cells, and this interaction was more in PC3 cells transfected with RUNX2 cDNA. Overexpression of RUNX2 augments the expression of metastasis-related genes (e.g., MMP-9 and osteopontin) which resulted in increased migration and tumorsphere formation.

CONCLUSIONS

We have shown here a strong functional relationship between CD44-ICD and RUNX2 in PC3 cells. RUNX2 forms a complex with CD44-ICD as a co-transcriptional factor, and this complex formation not only activates the expression of metastasis-related genes but also contributes to migration and tumorsphere formation. Therefore, RUNX2 and CD44-ICD are potential targets for anti-cancer therapy, and attenuation of their interaction may validate the regulatory effects of these proteins on cancer migration and progression.

Immunohistochemical expression of CD44, matrix metalloproteinase2 and matrix metalloproteinase9 in renal cell carcinomas

PURPOSE

The aim of our study was to investigate the clinicopathologic values of the expression of CD44, matrix metalloproteinase (MMP)2, and MMP9 in renal cell carcinoma (RCC).

PATIENTS AND METHODS

A total of 107 clear cell RCCs (ccRCCs) and 32 nonclear cell RCCs (non-ccRCCs) were examined for CD44, MMP2, and MMP9 expression by immunohistochemistry. The membrane and cytoplasmic expression levels of the 3 proteins were scored by semiquantitative methods, and the correlations of the 3 proteins with clinicopathological parameters were verified.

RESULTS

The expression levels of CD44, MMP2, and MMP9 were positively correlated with nuclear grade (grade 1-2 vs. grade 3-4) (P = 0.003, P < 0.001 and P < 0.001, respectively) in the ccRCCs, while in the non-ccRCCs, only CD44 expression was correlated with higher nuclear grade (grade 1-3 vs. grade 4) (P = 0.001). Furthermore, CD44 expression in ccRCCs and non-ccRCCs was correlated with shorter overall survival in the univariate analyses (P < 0.001 and P = 0.015, respectively). In the multivariate analysis, which accounted for age, sex, nuclear grade, and pathologic stage, CD44 expression was an independent predictor of shorter overall survival only in ccRCCs. Correlations among the 3 proteins were all positive in ccRCCs, but in non-ccRCCs, only MMP2 and MMP9 were positively correlated.

CONCLUSION

CD44 expression may play an important role in the progression of both ccRCC and non-ccRCC. CD44 expression in ccRCC may be associated with elevated MMP2 and MMP9 expression levels, which is in contrast to non-ccRCC. The different correlations between CD44, MMP2, and MMP9 in ccRCC and non-ccRCC can be useful in understanding the mechanisms of carcinogenesis and stratifying patients for therapeutic purposes.

Do Different Stemness Markers Identify Different Pools of Cancer Stem Cells in Malignancies: A Study on ER+ and ER-Breast Cancer Cell Lines

In view of popularity of cancer stem cell (CSC) model all events in evolution of cancer are being explained in that context. Breast cancer is first solid tumor in which CSCs were identified. We aimed to compare stemness profile of two major subtypes [Estrogen receptor positive (ER⁺) and negative (ER^-)] breast cancer using different sets of markers. Expression of CD44/CD24, CK/Vimentin, E-Cadherin/Fibronectin and percentage of side population (SP) was studied in ER⁺ (T47D) and ER^- (MDA-MB-231) cell lines by flow cytometry. Breast CSCs (BCSCs) were sorted using CD44⁺/CD24^-/low expression and SP analysis and cultured. BCSCs were then compared with Non-CSCs (NCSCs) for response to drugs (Paclitaxel and Cisplatin), Ki67 and ER expression. Results showed higher expression of stemness markers (CD44⁺/CD24^-/low, CK⁺/Vimentin⁺ and E-Cadherin^-/Fibrinectin^F+) in MDA-MB-231 cells. Percentage SP representing BCSCs was found to be significantly more in later (3.20 ± 0.002 cf. T47D 1.25% ± 0.0007). BCSCs were found to be more resistant to drugs as compared to NCSCs in both cell lines. ER expression was weak in BCSCs sorted from T47D as compared to NCSCs. Ki67 was expressed in both BCSCs and NCSCs. Differences in expression of stemness markers help to explain aggressive behavior, higher recurrence rate and metastatic potential of MDA-MB-231 cells. However, no correlation amongst different markers used suggests that they may be identifying varied populations of cells in tumor hierarchy. A weak ER expression in BCSCs may be strategy used by BCSCs to escape effect of hormone therapy in ER⁺ breast cancers.

Standard CD44 modulates YAP1 through a positive feedback loop in hepatocellular carcinoma

High expression levels of CD44 and YAP have been identified as poor prognostic factors in hepatocellular carcinoma (HCC). However, the mechanistic relationship between CD44 and YAP during HCC tumorigenesis remains largely unknown. To investigate the mutual regulation between standard CD44 (CD44S) and YAP1 in HCC cell lines and tissue samples, CD44S and YAP1 expression in 40 pairs of tumor samples and matched distal normal tissues from HCC patients was examined by immunohistochemical staining. High expression of either CD44S or YAP1 was associated with a younger age and worse pathology grade. In addition, high levels of CD44S and YAP1 were associated with increased vascular invasion and more severe liver cirrhosis, respectively. CD44S expression was positively correlated with YAP1 expression in these HCC tissues. In vitro experiments suggested that CD44S could positively regulate the expression of YAP1 and its target genes via the PI3K/Akt pathway in HCC cells. Moreover, CD44S is regulated by the YAP1/TEAD axis. These results reveal a novel positive feedback loop involving CD44S and YAP1, in which CD44S functions as both an upstream regulator and a downstream effector of YAP1 in HCC. This feedback loop might constitute a broadly conserved module for regulating cell proliferation and invasion during HCC tumorigenesis. Blocking this positive feedback loop that involves CD44S and YAP1 might represent a new approach for HCC treatment.

Antibody-modified liposomes for tumor-targeting delivery of timosaponin AIII

Introduction

Timosaponin AIII (TAIII), as a steroid saponin in Anemarrhena asphodeloides, has favorable potential as an antitumor candidate. However, its hydrophobicity and low bioavailability severely limit its in vivo antitumor efficacy.

Methods

To overcome this drawback, TAIII-loaded liposomes (LP) were prepared to improve TAIII solubility and extend its circulation time. Furthermore, anti-CD44 antibody-modified LP (CD44-LP) was prepared to enhance the therapeutic index of TAIII. The LP and CD44-LP were also characterized through their biological activity, target selective binding and uptake, and in vivo pharmacokinetics.

Results

Compared with free TAIII, both LP and CD44-LP possessed a desirable sustained-release profile in vitro, with ~14.2- and 10.7-fold longer TAIII half-life, respectively, and 1.7- and 1.9-fold larger area under the curve, respectively. LP and CD44-LP enhanced TAIII antitumor activity against HepG2 cells and in a xenograft mouse model without detectable toxicity. In particular, CD44-LP exhibited notably higher cytotoxicity than did LP, with a lower half-maximal inhibitory concentration (48 h). CD44-LP exhibited stronger tumor inhibition, and the tumor inhibitory effect was 1.3-fold that of LP. Furthermore, confocal laser scanning microscopy and in vivo near-infrared imaging of a xenograft mouse model revealed that compared with LP, CD44-LP could effectively enhance tumor accumulation.

Conclusion

Taken together, the results indicate that both CD44-LP and LP can considerably extend TAIII circulation time, increase tumor-targeted accumulation, and enhance antitumor activity. Thus, the anti-CD44 antibody-modified liposome is a promising candidate for treating CD44-positive cancer with considerable antitumor effects.