The role of the CD44/ezrin complex in cancer metastasis

Biomimetic "nano-spears" for CAFs-targeting: splintered three "shields" with enhanced cisplatin anti-TNBC efficiency

The treatment dilemma of triple-negative breast cancer (TNBC) revolves around drug resistance and metastasis. Cancer-associated fibroblasts (CAFs) contribute to cisplatin (Cis) resistance and further metastasis in TNBC, making TNBC a difficult-to-treat disease. The dense stromal barrier which restricts drug delivery, invasive phenotype of tumor cells, and immunosuppressive tumor microenvironment (TME) induced by CAFs serve as three "shields" for TNBC against Cis therapy. Here, we designed a silybin-loaded biomimetic nanoparticle coated with anisamide-modified red blood cell membrane (ARm@SNP) as a "nanospear" for CAFs-targeting, which could shatter the "shields" and significantly exhibit inhibitory effect on 4T1 cells in combination with Cis both in vitro and in vivo. The ARm@SNP/Cis elicited 4T1 tumor growth arrest and destroyed three "shields" as follows: disintegrating the stromal barrier by inhibiting blood vessels growth and the expression of fibronectin; decreasing 4T1 cell invasion and metastasis by affecting the TGF-β/Twist/EMT pathway which impeded EMT activation; reversing the immunosuppressive microenvironment by increasing the activity and infiltration of immunocompetent cells. Based on CAFs-targeting, ARm@SNP reversed the resistance of Cis, remodeled the TME and inhibited invasion and metastasis while significantly improving the therapeutic effect of Cis on 4T1 tumor-bearing mice, providing a promising approach for treating intractable TNBC.

ARHGAP18-ezrin functions as an autoregulatory module for RhoA in the assembly of distinct actin-based structures

The location of different actin-based structures is largely regulated by Rho GTPases through specific effectors. We use the apical aspect of epithelial cells as a model system to investigate how RhoA is locally regulated to contribute to two distinct adjacent actin-based structures. Assembly of the non-muscle myosin-2 filaments in the terminal web is dependent on RhoA activity, and assembly of the microvilli also requires active RhoA for phosphorylation and activation of ezrin. We show that the RhoGAP, ARHGAP18, is localized by binding active microvillar ezrin, and this interaction enhances ARHGAP18's RhoGAP activity. We present a model where ezrin-ARHGAP18 acts as a negative autoregulatory module to locally reduce RhoA activity in microvilli. Consistent with this model, loss of ARHGAP18 results in disruption of the distinction between microvilli and the terminal web including aberrant assembly of myosin-2 filaments forming inside microvilli. Thus, ARHGAP18, through its recruitment and activation by ezrin, fine-tunes the local level of RhoA to allow for the appropriate distribution of actin-based structures between the microvilli and terminal web. As RhoGAPs vastly outnumber Rho GTPases, this may represent a general mechanism whereby individual Rho effectors drive specific actin-based structures.

Ezrin Inhibition Overcomes Acquired Resistance to Vemurafenib in BRAFV600E-Mutated Colon Cancer and Melanoma Cells In Vitro

Despite the advancements in targeted therapy for BRAFV600E-mutated metastatic colorectal cancer (mCRC), the development of resistance to BRAFV600E inhibition limits the response rate and durability of the treatment. Better understanding of the resistance mechanisms to BRAF inhibitors will facilitate the design of novel pharmacological strategies for BRAF-mutated mCRC. The aim of this study was to identify novel protein candidates involved in acquired resistance to BRAFV600E inhibitor vemurafenib in BRAFV600E-mutated colon cancer cells using an integrated proteomics approach. Bioinformatic analysis of obtained proteomics data indicated actin-cytoskeleton linker protein ezrin as a highly ranked protein significantly associated with vemurafenib resistance whose overexpression in the resistant cells was additionally confirmed at the gene and protein level. Ezrin inhibition by NSC305787 increased anti-proliferative and pro-apoptotic effects of vemurafenib in the resistant cells in an additive manner, which was accompanied by downregulation of CD44 expression and inhibition of AKT/c-Myc activities. We also detected an increased ezrin expression in vemurafenib-resistant melanoma cells harbouring the BRAFV600E mutation. Importantly, ezrin inhibition potentiated anti-proliferative and pro-apoptotic effects of vemurafenib in the resistant melanoma cells in a synergistic manner. Altogether, our study suggests a role of ezrin in acquired resistance to vemurafenib in colon cancer and melanoma cells carrying the BRAFV600E mutation and supports further pre-clinical and clinical studies to explore the benefits of combined BRAF inhibitors and actin-targeting drugs as a potential therapeutic approach for BRAFV600E-mutated cancers.

Ez-Metastasizing: The Crucial Roles of Ezrin in Metastasis

Ezrin is the cytoskeletal organizer and functions in the modulation of membrane-cytoskeleton interaction, maintenance of cell shape and structure, and regulation of cell-cell adhesion and movement, as well as cell survival. Ezrin plays a critical role in regulating tumor metastasis through interaction with other binding proteins. Notably, Ezrin has been reported to interact with immune cells, allowing tumor cells to escape immune attack in metastasis. Here, we review the main functions of Ezrin, the mechanisms through which it acts, its role in tumor metastasis, and its potential as a therapeutic target.

Amino acid profile changes during enrichment of spheroid cells with cancer stem cell properties in MCF-7 and MDA-MB-231 cell lines

BACKGROUND

Cancer stem cells (CSCs), subpopulations of cancer cells, are responsible for tumor progression, metastasis, and relapse. Changes in amino acid metabolism are linked to breast cancer recurrence and metastasis.

AIMS

This study aimed to evaluate the changes in the amino acid profile in MCF-7 and MDA-MB-231 cells during spheroid formation to discover the specific metabolic properties in CSCs.

METHODS

MCF-7 and MDA-MB-231 breast cancer cells were cultured as spheroids and evaluated to characterize their CSC properties. The characteristics of CSC were evaluated by examining the expression of CSC markers and conducting drug resistance assays. In addition, amino acid profile change during the enrichment of breast cancer stem cells in the spheroids was investigated by high-performance liquid chromatography (HPLC).

RESULTS

The results indicated that out of 20 different amino acids analyzed, 19 of them decreased during the spheroid formation process. Alanine, lysine, phenylalanine, threonine, and glycine showed significant reductions in the conditioned media of both cell lines in the spheroid form compared to the monolayer cells. Only one of the amino acids increased in MCF-7 and MDA-MB-231 spheroids (histidine and serine, respectively).

CONCLUSION

Our results suggest that certain amino acids identified in this study can be used for a better understanding of the molecular mechanisms associated with breast cancer stem cell formation.

FERM domains recruit ample PI(4,5)P2s to form extensive protein-membrane attachments

The four-point-one ezrin-radixin-moesin homology (FERM) protein domain is a multifunctional protein-lipid binding site, constituting an integral part of numerous membrane-associated proteins. Its interaction with the lipid phosphatidylinositol-4,5-bisphosphate (PIP2), located at the inner leaflet of eukaryotic plasma membranes, is important for localization, anchorage, and activation of FERM-containing proteins. FERM-PIP2 complexes structurally determined so far exclusively feature a 1:1 binding stoichiometry of protein and lipid, with a few basic FERM residues neutralizing the -4 charge of the bound PIP2. Whether this picture from static crystal structures also applies to the dynamic interaction of FERM domains on PIP2 membranes is unknown. We here quantified the stoichiometry of FERM-PIP2 binding in a lipid bilayer using atomistic molecular dynamics simulations and experiments on solid supported membranes for the FERM domains of focal adhesion kinase and ezrin. In contrast to the structural data, we find much higher average stoichiometries of FERM-PIP2 binding, amounting to 1:3 or 1:4 ratios, respectively. In simulations, the full set of basic residues at the membrane interface, 7 and 15 residues for focal adhesion kinase and ezrin, respectively, engages in PIP2 interactions. In addition, Na ions enter the FERM-membrane binding interface, compensating negative PIP2 charges in case of high charge surpluses from bound PIP2. We propose the multivalent binding of FERM domains to PIP2 in lipid bilayers to significantly enhance the stability of FERM-membrane binding and to render the FERM-membrane linkage highly adjustable.

Proteome derangement in malignant epithelial cells and its stroma following exposure to 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone

Discovering novel changes in the proteome of malignant lung epithelial cells and/or the tumor-microenvironment is paramount for diagnostic, prognostic, and/or therapy development. A time-dependent 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced mouse lung tumor model was used to screen the proteome of lung tumors. NNK-transformed human lung epithelial BEAS-2B cells were then established to evaluate the epithelial cell-specific protein changes. A duration-dependent increase of tumor burden was observed in NNK-treated mice, 2/12 (17%), 8/12 (67%), 9/12 (75%), and 10/10 (100%) at weeks 8, 12, 16, and 20 after the NNK exposure, respectively. A total of 25 differentially expressed proteins (≥ twofold change), predominantly structural, signaling, and metabolic proteins, were detected by two-dimensional difference gel electrophoresis and identified by mass spectrometry. Calregulin, ezrin, histamine releasing factor (HRF), and inorganic pyrophosphatase 1 (PPA1) exhibited changes and were further confirmed via immunoblotting. In addition, immunohistochemistry (IHC) analysis indicated upregulated E-cadherin and decreased vimentin expression in epithelial cells of tumor tissues. Acquisition of a neoplastic phenotype in NNK-transformed BEAS-2B cells was demonstrated by enhanced wound closure and increased anchorage independent colony formation. In transformed BEAS-2B cells, protein expression of E-cadherin, ezrin, and PPA1 (but not calregulin and HRF) was upregulated, as was observed in tumor tissues IHC staining using mouse lung tumor tissues further revealed that HRF upregulation was not lung epithelial cell specific. Altogether, tumorigenesis after NNK exposure may be initiated by protein dysregulation in lung epithelial cells together with proteome derangement derived from other cell types existing in the tumor-microenvironment.

Glioblastoma Spheroid Invasion through Soft, Brain-Like Matrices Depends on Hyaluronic Acid-CD44 Interactions

Increased secretion of hyaluronic acid (HA), a glycosaminoglycan abundant in the brain extracellular matrix (ECM), correlates with worse clinical outcomes for glioblastoma (GBM) patients. GBM cells aggressively invade the brain parenchyma while encountering spatiotemporal changes in their local ECM, including HA concentration. To investigate how varying HA concentrations affect GBM invasion, patient-derived GBM cells are cultured within a soft, 3D matrix in which HA concentration is precisely varied and cell migration observed. Data demonstrate that HA concentration can determine the invasive activity of patient-derived GBM cells in a biphasic and highly sensitive manner, where the absolute concentration of HA at which cell migration peaked is specific to each patient-derived line. Furthermore, evidence that this response relies on phosphorylated ezrin, which interacts with the intracellular domain of HA-engaged CD44 to effectively link the actin cytoskeleton to the local ECM is provided. Overall, this study highlights CD44-HA binding as a major mediator of GBM cell migration that acts independently of integrins and focal adhesion complexes and suggests that targeting HA-CD44-ezrin interactions represents a promising therapeutic strategy to prevent tumor cell invasion in the brain.

PLEKHH2 binds β-arrestin1 through its FERM domain, activates FAK/PI3K/AKT phosphorylation, and promotes the malignant phenotype of non-small cell lung cancer

PLEKHH2 is an important FERM domain containing-protein. However, the role of PLEKHH2 in human solid tumors has not been reported yet. We report that PLEKHH2 showed enhanced cytoplasmic expression in non-small cell lung cancer (NSCLC). Its overexpression was positively correlated with high TNM stage, low differentiation, lymphatic node metastasis, and poor prognosis. In A549 and H1299 cells, high expression of PLEKHH2 significantly promoted cell proliferation, migration, invasion, and increased the expression of proliferation- and invasion-related proteins. It also enhanced the phosphorylation of FAK and promoted the activity of the PI3K/AKT pathway. Immunofluorescence and co-immunoprecipitation analyses were performed to elucidate the molecular mechanism underlying PLEKHH2-mediated regulation of proliferation and invasion in lung cancer cells. Upon transfection of full length PLEKHH2 or its FERM domain, we observed enhanced binding of PLEKHH2 to β-arrestin1, whereas FAK- β-arrestin1 binding was diminished and this led to an increase in FAK phosphorylation. PLEKHH2-mutant plasmids without the FERM domain could not effectively promote its binding to β-arrestin1, activation of FAK phosphorylation, PI3K/AKT activation, or the malignant phenotype. Our findings suggested that PLEKHH2 is an important oncogene in NSCLC. PLEKHH2 binding to β-arrestin1 through the FERM domain competitively inhibits β-arrestin1 binding to FAK, which causes the dissociation of FAK from the FAK-β-arrestin1 complex. Furthermore, the dissociation of FAK promotes its autophosphorylation, activates the PI3K/AKT signaling pathway, and subsequently promotes lung cancer cell proliferation, migration, and invasion. These results provide evidence for the potential use of PLEKHH2 inhibition as an anticancer therapy.

Cell-in-Cell Events in Oral Squamous Cell Carcinoma

For over a century, cells within other cells have been detected by pathologists as common histopathological findings in tumors, being generally identified as “cell-in-cell” structures. Despite their characteristic morphology, these structures can originate from various processes, such as cannibalism, entosis and emperipolesis. However, only in the last few decades has more attention been given to these events due to their importance in tumor development. In cancers such as oral squamous cell carcinoma, cell-in-cell events have been linked to aggressiveness, metastasis, and therapeutic resistance. This review aims to summarize relevant information about the occurrence of various cell-in-cell phenomena in the context of oral squamous cell carcinoma, addressing their causes and consequences in cancer. The lack of a standard terminology in diagnosing these events makes it difficult to classify the existing cases and to map the behavior and impacts of these structures. Despite being frequently reported in oral squamous cell carcinoma and other cancers, their impacts on carcinogenesis aren’t fully understood. Cell-in-cell formation is seen as a survival mechanism in the face of a lack of nutritional availability, an acid microenvironment and potential harm from immune cell defense. In this deadly form of competition, cells that engulf other cells establish themselves as winners, taking over as the predominant and more malignant cell population. Understanding the link between these structures and more aggressive behavior in oral squamous cell carcinoma is of paramount importance for their incorporation as part of a therapeutic strategy.

CD44 In Sarcomas: A Comprehensive Review and Future Perspectives

It is widely accepted that the tumor microenvironment, particularly the extracellular matrix, plays an essential role in the development of tumors through the interaction with specific protein-membrane receptors. One of the most relevant proteins in this context is the transmembrane protein CD44. The role of CD44 in tumor progression, invasion, and metastasis has been well established in many cancers, although a comprehensive review concerning its role in sarcomas has not been published. CD44 is overexpressed in most sarcomas and several in vitro and in vivo experiments have shown a direct effect on tumor progression, dissemination, and drug resistance. Moreover, CD44 has been revealed as a useful marker for prognostic and diagnostic (CD44v6 isoform) in osteosarcoma. Besides, some innovative treatments such as HA-functionalized liposomes therapy have become an excellent CD44-mediated intracellular delivery system for osteosarcoma. Unfortunately, the reduced number of studies deciphering the prognostic/diagnostic value of CD44 in other sarcoma subgroups, neither than osteosarcoma, in addition to the low number of patients involved in those studies, have produced inconclusive results. In this review, we have gone through the information available on the role of CD44 in the development, maintenance, and progression of sarcomas, analyzing their implications at the prognostic, therapeutic, and mechanistic levels. Moreover, we illustrate how research involving the specific role of CD44 in the different sarcoma subgroups could suppose a chance to advance towards a more innovative perspective for novel therapies and future clinical trials.

Pathophysiological Roles of Actin-Binding Scaffold Protein, Ezrin

Ezrin is one of the members of the ezrin/radixin/moesin (ERM) family of proteins. It was originally discovered as an actin-binding protein in the microvilli structure about forty years ago. Since then, it has been revealed as a key protein with functions in a variety of fields including cell migration, survival, and signal transduction, as well as functioning as a structural component. Ezrin acts as a cross-linker of membrane proteins or phospholipids in the plasma membrane and the actin cytoskeleton. It also functions as a platform for signaling molecules at the cell surface. Moreover, ezrin is regarded as an important target protein in cancer diagnosis and therapy because it is a key protein involved in cancer progression and metastasis, and its high expression is linked to poor survival in many cancers. Small molecule inhibitors of ezrin have been developed and investigated as candidate molecules that suppress cancer metastasis. Here, we wish to comprehensively review the roles of ezrin from the pathophysiological points of view.

The raft cytoskeleton binding protein complexes personate functional regulators in cell behaviors

Several cytoskeleton proteins interact with raft proteins to form raft-cytoskeleton binding protein complexes (RCPCs) that control cell migration and adhesion. The purpose of this paper is to review the latest research on the modes and mechanisms by which a RCPC controls different cellular functions. This paper discusses RCPC composition and its role in cytoskeleton reorganization, as well as the latest developments in molecular mechanisms that regulate cell adhesion and migration under normal conditions. In addition, the role of some external stimuli (such as stress and chemical signals) in this process is further debated, and meanwhile potential mechanisms for RCPC to regulate lipid raft fluidity is proposed. Thus, this review mainly contributes to the understanding of RCPC signal transduction in cells. Additionally, the targeted signal transduction of RCPC and its mechanism connection with cell behaviors will provide a logical basis for the development of unified interventions to combat metastasis related dysfunction and diseases.

CD44 Variant Exon 6 Isoform Expression as a Potential Predictor of Lymph Node Metastasis in Invasive Breast Carcinoma of No Special Type

Background

Invasive breast carcinoma of no special type (IBC-NST) is the most widespread invasive carcinoma subtype causing primarily regional metastases of the lymphatic node (LNM). The capacity of CD44 variant exon 6 (CD44v6) expression as an LNM predictor biomarker in IBC-NST was explored.

Methods

We conducted a cross-sectional research with 48 paraffin blocks containing IBC-NST primary tumors that were divided into two groups by LNM. The assessment has been carried out in terms of age, tumor size, tumor grade, lymphovascular invasion (LVI), and CD44v6 expression. The expression of CD44v6 was analyzed on the grounds of immunohistochemical (IHC) staining, while other data were taken from archives. Statistical analysis is carried out by univariate, multivariate, and AUROC.

Results

CD44v6 exhibits a dominant expression in IBC-NST tumor cells. Univariate analysis revealed a significant association between CD44v6 and LNM status (p = 0.001). Multiple logistic regression results showed that CD44v6 expression and LVI were significantly associated with LNM with OR 10.7 (95% CI: 2.43 to 47.08) and 6.22 (95% CI: 1.4 to 27.88), respectively. CD44v6 expression was able to discriminate against LNM with AUROC 0.863 ± 0.053 (95% CI: 0.759 to 0.967) at the H-score cut-off 133.889 (75% sensitivity and 83.3% specificity).

Conclusion

CD44v6 expression and LVI are potential predictors of LNM in IBC-NST. The H-score cut-off of the CD44v6 expression can also be used as a threshold for classification in further investigation.

Epitope Mapping of the Anti-CD44 Monoclonal Antibody (C44Mab-46) Using the REMAP Method

CD44 functions as a major hyaluronan receptor on most cell types, with roles in cell adhesion, migration, proliferation, differentiation, and survival. The CD44 gene comprises 20 exons, with alternative splicing producing many different isoforms. CD44 variant isoforms exhibit tissue-specific expression patterns and have been studied as therapeutic targets for several cancers; therefore, anti-CD44 monoclonal antibodies (mAbs) are useful for investigating CD44 expression in various cancers. Previously, we established an anti-CD44 mAb, C₄₄Mab-46 (IgG₁, κ), by immunizing mice with the CD44v3-10 ectodomain. Although C₄₄Mab-46 recognized all CD44 isoforms, the binding epitope of C₄₄Mab-46 has not been determined. In this study, we first checked the reactivity of C₄₄Mab-46 to several CD44v3-10 deletion mutants such as dN79, dN124, dN147, and dN224. We found the N-terminus of the C₄₄Mab-46-binding epitope between residues 147 and 224 of CD44v3-10. We next investigated this epitope using a novel mapping system: RIEDL insertion for epitope mapping (REMAP) method. We constructed 31 CD44 standard (CD44s) mutants where the RIEDL tag was inserted into the expected epitope region in CD44s. We observed that the C₄₄Mab-46 epitope constituted five amino acids: ₁₇₄-TDDDV-₁₇₈ of CD44s. Thus, the REMAP method could be used to determine mAb binding epitopes for membrane proteins.

The CD44/COL17A1 pathway promotes the formation of multilayered, transformed epithelia

At the early stage of cancer development, oncogenic mutations often cause multilayered epithelial structures. However, the underlying molecular mechanism still remains enigmatic. By performing a series of screenings targeting plasma membrane proteins, we have found that collagen XVII (COL17A1) and CD44 accumulate in RasV12-, Src-, or ErbB2-transformed epithelial cells. In addition, the expression of COL17A1 and CD44 is also regulated by cell density and upon apical cell extrusion. We further demonstrate that the expression of COL17A1 and CD44 is profoundly upregulated at the upper layers of multilayered, transformed epithelia in vitro and in vivo. The accumulated COL17A1 and CD44 suppress mitochondrial membrane potential and reactive oxygen species (ROS) production. The diminished intracellular ROS level then promotes resistance against ferroptosis-mediated cell death upon cell extrusion, thereby positively regulating the formation of multilayered structures. To further understand the functional role of COL17A1, we performed comprehensive metabolome analysis and compared intracellular metabolites between RasV12 and COL17A1-knockout RasV12 cells. The data imply that COL17A1 regulates the metabolic pathway from the GABA shunt to mitochondrial complex I through succinate, thereby suppressing the ROS production. Moreover, we demonstrate that CD44 regulates membrane accumulation of COL17A1 in multilayered structures. These results suggest that CD44 and COL17A1 are crucial regulators for the clonal expansion of transformed cells within multilayered epithelia, thus being potential targets for early diagnosis and preventive treatment for precancerous lesions.

Role of Cholesterol and Lipid Rafts in Cancer Signaling: A Promising Therapeutic Opportunity?

Cholesterol is a lipid molecule that plays an essential role in a number of biological processes, both physiological and pathological. It is an essential structural constituent of cell membranes, and it is fundamental for biosynthesis, integrity, and functions of biological membranes, including membrane trafficking and signaling. Moreover, cholesterol is the major lipid component of lipid rafts, a sort of lipid-based structures that regulate the assembly and functioning of numerous cell signaling pathways, including those related to cancer, such as tumor cell growth, adhesion, migration, invasion, and apoptosis. Considering the importance of cholesterol metabolism, its homeostasis is strictly regulated at every stage: import, synthesis, export, metabolism, and storage. The alterations of this homeostatic balance are known to be associated with cardiovascular diseases and atherosclerosis, but mounting evidence also connects these behaviors to increased cancer risks. Although there is conflicting evidence on the role of cholesterol in cancer development, most of the studies consistently suggest that a dysregulation of cholesterol homeostasis could lead to cancer development. This review aims to discuss the current understanding of cholesterol homeostasis in normal and cancerous cells, summarizing key findings from recent preclinical and clinical studies that have investigated the role of major players in cholesterol regulation and the organization of lipid rafts, which could represent promising therapeutic targets.

Bioinformatics analysis of lncRNA‑associated ceRNA network in melanoma

Melanoma is an extremely malignant tumor with early metastasis and high mortality. Little is known about the process of by which melanoma occurs, as its mechanism is very complex and only limited data are available on its long non-coding RNA (lncRNA)-associated competing endogenous RNAs (ceRNAs). The purpose of this study was to screen out potential prognostic molecules and identify a ceRNA network related to the occurrence of melanoma. We screened 169 differentially expressed mRNAs (DEmRNAs) from E-MTAB-1862 and GSE3189; gene ontology (GO) enrichment analysis showed that these genes were closely related to the development of skin. In the protein-protein interaction network, we screened out a total of 19 hub genes. Furthermore, we predicted the microRNAs (miRNAs) that regulate hub genes using the miRWalk database and then intersected these with GSE35579, resulting in nine DEmiRNAs. We also predicted the lncRNAs that regulate the miRNAs using the LncBasev.2 database. According to the ceRNA hypothesis, and based on the intersection of the DElncRNAs with merged GTEx and TCGA data, we obtained 20 DElncRNAs. A total of four DEmRNAs, nine DEmiRNAs, and 20 DElncRNAs were included in the ceRNA network. Based on Cox stepwise regression and survival analysis, we identified five biomarkers, ZSCAN16-AS1, LINC00520, XIST, DTL, and let-7a-5p, and obtained risk scores. The results showed that most of the differentially expressed genes were related to epithelial-mesenchymal transition (EMT) in melanoma. Finally, we obtained a LINC00520/let-7a-5p/DTL molecular regulatory network. These results suggest that ceRNA networks have an important role in evaluating the prognosis of patients with melanoma and provide a new experimental basis for exploring the EMT process in the development of melanoma.

The impact of reactive oxygen species in the development of cardiometabolic disorders: a review

Oxidative stress, an alteration in the balance between reactive oxygen species (ROS) generation and antioxidant buffering capacity, has been implicated in the pathogenesis of cardiometabolic disorders (CMD). At physiological levels, ROS functions as signalling mediators, regulates various physiological functions such as the growth, proliferation, and migration endothelial cells (EC) and smooth muscle cells (SMC); formation and development of new blood vessels; EC and SMC regulated death; vascular tone; host defence; and genomic stability. However, at excessive levels, it causes a deviation in the redox state, mediates the development of CMD. Multiple mechanisms account for the rise in the production of free radicals in the heart. These include mitochondrial dysfunction and uncoupling, increased fatty acid oxidation, exaggerated activity of nicotinamide adenine dinucleotide phosphate oxidase (NOX), reduced antioxidant capacity, and cardiac metabolic memory. The purpose of this study is to discuss the link between oxidative stress and the aetiopathogenesis of CMD and highlight associated mechanisms. Oxidative stress plays a vital role in the development of obesity and dyslipidaemia, insulin resistance and diabetes, hypertension via various mechanisms associated with ROS-led inflammatory response and endothelial dysfunction.

Ezrin is essential for the entry of Japanese encephalitis virus into the human brain microvascular endothelial cells

Japanese encephalitis virus (JEV) remains the predominant cause of viral encephalitis worldwide. It reaches the central nervous system upon crossing the blood-brain barrier through pathogenic mechanisms that are not completely understood. Here, using a high-throughput siRNA screening assay combined with verification experiments, we found that JEV enters the primary human brain microvascular endothelial cells (HBMEC) through a caveolae-mediated endocytic pathway. The role of ezrin, an essential host factor for JEV entry based on our screening, in caveolae-mediated JEV internalization was investigated. We observed that JEV internalization in HBMEC is largely dependent on ezrin-mediated actin cytoskeleton polymerization. Moreover, Src, a protein predicted by a STRING database search, was found to be required in JEV entry. By a variety of pharmacological inhibition and immunoprecipitation assays, we found that Src, ezrin, and caveolin-1 were sequentially activated and formed a complex during JEV infection. A combination of in vitro kinase assay and subcellular analysis demonstrated that ezrin is essential for Src-caveolin-1 interactions. In vivo, both Src and ezrin inhibitors protected ICR suckling mice against JEV-induced mortality and diminished mouse brain viral load. Therefore, JEV entry into HBMEC requires the activation of the Src-ezrin-caveolin-1 signalling axis, which provides potential targets for restricting JEV infection.

CD44 cross-linking increases malignancy of breast cancer via upregulation of p-Moesin

Background

CD44 is highly expressed in most cancer cells and its cross-linking pattern is closely related to tumor migration and invasion. However, the underlying molecular mechanism regarding CD44 cross-linking during cancer cell metastasis is poorly understood. Therefore, the purpose of this study was to explore whether disruption of CD44 cross-linking in breast cancer cells could prevent the cells migration and invasion and determine the effects of CD44 cross-linking on the malignancy of the cancer cells.

Methods

The expression of CD44, CD44 cross-linking and Moesin phosphorylation in breast cancer cells was assessed by Western Blot assays. Effects of CD44 cross-linking on tumor metastasis were evaluated by Transwell assay. The effects of CD44 cross-linking disruption on cell viability were assessed using CCK-8 assays. The expression of p-Moesin between normal and breast cancer tissues was examined by immunohistochemical staining.

Results

High expression of CD44 cross-linking was found in invasive breast cancer cells (BT-549 and MDA-MB-231), which is associated with the malignancy of breast cancer. The expressions of ERM complex in a panel of breast cancer cell lines indicate that Moesin and its phosphorylation may play a significant role in cell metastasis. Moesin phosphorylation was inhibited by CD44 de-crosslinking in breast cancer cells and Moesin shRNA knockdown attenuated the promotion of CD44 cross-linking on cell migration and invasion. Finally, immunohistochemistry results demonstrated that p-Moesin was overexpressed in primary and metastatic cancers.

Conclusions

Our study suggested that CD44 cross-linking could elevate p-Moesin expression and further affect migration and invasion of breast cancer cells. These results also indicate that p-Moesin may be useful in future targeted cancer therapy.

Tumour suppression through modulation of neprilysin signaling: A comprehensive review

Peptidases are emerging as promising drug targets in tumour suppression. Neprilysin, also known as neutral endopeptidase, is a cell surface peptidase that degrades various peptides such as angiotensin II, endothelin I, Substance P, etc., and reduces their local concentration. Neprilysin is expressed in various tissues such as kidney, prostate, lung, breast, brain, intestine, adrenal gland, etc. The tumour-suppressor mechanisms of neprilysin include its peptidase activity that degrades mitogenic growth factors such as fibroblast growth factor-2 and insulin-like growth factors, and the protein-protein interaction of neprilysin with phosphatase and tensin homolog, focal adhesion kinase, ezrin/radixin/moesin, and phosphoinositide 3-kinase. Studies have shown that the levels of neprilysin play an important role in malignancies. NEP is downregulated in prostate, renal, lung, breast, urothelial, cervical, hepatic cancers, etc. Histone deacetylation and hypermethylation of the neprilysin promoter region are the common mechanisms involved in the downregulation of neprilysin. Downregulation of the peptidase promotes angiogenesis, cell survival and cell migration. This review presents an overview of the role of neprilysin in malignancy, the tumour suppression mechanisms of neprilysin, the epigenetic mechanisms responsible for downregulation of neprilysin, and the potential pharmacological approaches to upregulate neprilysin levels and its activity.

The Role of CD44 and RHAMM in Endometrial (Endometrioid Type) Cancer: An Immunohistochemical Study

Hyaluronan controls cell migration, differentiation, and proliferation, and it is involved in tumor invasion. The extracellular matrix containing hyaluronan regulates cell behavior via cell surface receptors such as CD44 and receptor for hyaluronan-mediated motility (RHAMM, CD168). We investigated the expression of CD44 and RHAMM in tissue samples of endometrial cancer and the relation of their expression with clinicopathologic parameters of patients. In order to evaluate the value of CD44 and RHAMM as prognostic factors, we investigated the relation of their expression with patients' survival. Our results demonstrated a statistically significant correlation with the depth of myometrial invasion, lymphovascular invasion (LVSI), The International Federation of Gynecology and Obstetrics stage of disease, and, in the case of RHAMM expression, a significant correlation with histologic tumor grade as well. CD44 expression was present in the cell membrane in all cases, but in a proportion of tumors in the cytoplasm as well. In this group of patients, we noticed a significantly greater number of cases with deeper myometrial invasion and LVSI. Finally, we sorted out the group of tumors with simultaneous strong CD44 and strong RHAMM expression, and found a statistically significant correlation with the depth of myometrial invasion and LVSI. Using an univariate analysis, we demonstrated that, in our sample of patients, CD44 expression showed a statistically significant influence on patients' 5-year survival. However, using a multivariate Cox regression analysis, neither CD44 nor RHAMM confirmed themselves as independent prognostic factors.

Deciphering the Molecular Landscape of Cutaneous Squamous Cell Carcinoma for Better Diagnosis and Treatment

Cutaneous squamous cell carcinoma (cSCC) is a common type of neoplasia, representing a terrible burden on patients' life and clinical management. Although it seldom metastasizes, and most cases can be effectively treated with surgical intervention, once metastatic cSCC displays considerable aggressiveness leading to the death of affected individuals. No consensus has been reached as to which features better characterize the aggressive behavior of cSCC, an achievement hindered by the high mutational burden caused by chronic ultraviolet light exposure. Even though some subtypes have been recognized as high risk variants, depending on certain tumor features, cSCC that are normally thought of as low risk could pose an increased danger to the patients. In light of this, specific genetic and epigenetic markers for cutaneous SCC, which could serve as reliable diagnostic markers and possible targets for novel treatment development, have been searched for. This review aims to give an overview of the mutational landscape of cSCC, pointing out established biomarkers, as well as novel candidates, and future possible molecular therapies for cSCC.

Ezrin T567 phosphorylation regulates migration and invasion of ectopic endometrial stromal cells by changing actin cytoskeleton

AIMS

The enhanced ability of endometrial cell migration and invasion is the foundation for formation of ectopic lesions in endometriosis. Ezrin has been reported to regulate cell motility by remodeling the cytoskeleton. However, little is known about the mechanisms through which ezrin remodels the cytoskeleton and cell structure to promote cell motility in endometriosis.

METHODS

In our study, expression and distribution of ezrin, and Rho pathway were detected through immunohistochemical analysis. The effects of inhibiting ezrin T567 phosphorylation on Rho signaling pathway and cytoskeleton were investigated through western blot, transmission electron microscopy and immunofluorescence analysis.

KEY FINDINGS

We found that the expression of ezrin and Rho pathway was higher in ectopic endometrium. NSC305787 inhibited the phosphorylation of ezrin T567, resulting in decreased expression of Rho pathway and reduced filopodia formation in ectopic endometrial stromal cells.

SIGNIFICANCE

Taken together, our study suggested that ezrin T567 phosphorylation modulated migration and invasion of ectopic ESCs through actin reconstructions, which may serve as a novel therapeutic target in ovarian endometriosis.

Ezrin interacts with L-periaxin by the "head to head and tail to tail" mode and influences the location of L-periaxin in Schwann cell RSC96

In the peripheral nervous system (PNS), Schwann cells (SCs) are required for the myelination of axons. Periaxin (PRX), one of the myelination proteins expressed in SCs, is critical for the normal development and maintenance of PNS. As a member of the ERM (ezrin-radxin-moesin) protein family, ezrin holds our attention since their link to the formation of the nodes of Ranvier. Furthermore, PRX and ezrin are co-expressed in cytoskeletal complexes with periplakin and desmoyokin in lens fiber cells. In the present study, we observed that L-periaxin and ezrin interacted in a "head to head and tail to tail" mode in SC RSC96 through NLS3 region of L-periaxin with F3 subdomain of ezrin interaction, and the region of L-periaxin (residues 1368-1461) with ezrin (residues 475-557) interaction. A phosphorylation-mimicking mutation of ezrin resulted in L-periaxin accumulation on SC RSC96 membrane. Ezrin could inhibit the self-association of L-periaxin, and ezrin overexpression in sciatic nerve injury rats could facilitate the repair of impaired myelin sheath. Therefore, the interaction between L-periaxin and ezrin may adopt a close form to complete protein accumulation and to participate in myelin sheath maintenance.

CD44 contributes to hyaluronan-mediated insulin resistance in skeletal muscle of high-fat-fed C57BL/6 mice

Extracellular matrix hyaluronan is increased in skeletal muscle of high-fat-fed insulin-resistant mice, and reduction of hyaluronan by PEGPH20 hyaluronidase ameliorates diet-induced insulin resistance (IR). CD44, the main hyaluronan receptor, is positively correlated with type 2 diabetes. This study determines the role of CD44 in skeletal muscle IR. Global CD44-deficient (cd44^-/-) mice and wild-type littermates (cd44^+/+) were fed a chow diet or 60% high-fat diet for 16 wk. High-fat-fed cd44^-/- mice were also treated with PEGPH20 to evaluate its CD44-dependent action. Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp (ICv). High-fat feeding increased muscle CD44 protein expression. In the absence of differences in body weight and composition, despite lower clamp insulin during ICv, the cd44^-/- mice had sustained glucose infusion rate (GIR) regardless of diet. High-fat diet-induced muscle IR as evidenced by decreased muscle glucose uptake (Rg) was exhibited in cd44^+/+ mice but absent in cd44^-/- mice. Moreover, gastrocnemius Rg remained unchanged between genotypes on chow diet but was increased in high-fat-fed cd44^-/- compared with cd44^+/+ when normalized to clamp insulin concentrations. Ameliorated muscle IR in high-fat-fed cd44^-/- mice was associated with increased vascularization. In contrast to previously observed increases in wild-type mice, PEGPH20 treatment in high-fat-fed cd44^-/- mice did not change GIR or muscle Rg during ICv, suggesting a CD44-dependent action. In conclusion, genetic CD44 deletion improves muscle IR, and the beneficial effects of PEGPH20 are CD44-dependent. These results suggest a critical role of CD44 in promoting hyaluronan-mediated muscle IR, therefore representing a potential therapeutic target for diabetes.

Transcriptional profiling of circulating tumor cells in multiple myeloma: a new model to understand disease dissemination

The reason why a few myeloma cells egress from the bone marrow (BM) into peripheral blood (PB) remains unknown. Here, we investigated molecular hallmarks of circulating tumor cells (CTCs) to identify the events leading to myeloma trafficking into the bloodstream. After using next-generation flow to isolate matched CTCs and BM tumor cells from 32 patients, we found high correlation in gene expression at single-cell and bulk levels (r ≥ 0.94, P = 10^-16), with only 55 genes differentially expressed between CTCs and BM tumor cells. CTCs overexpressed genes involved in inflammation, hypoxia, or epithelial-mesenchymal transition, whereas genes related with proliferation were downregulated in CTCs. The cancer stem cell marker CD44 was overexpressed in CTCs, and its knockdown significantly reduced migration of MM cells towards SDF1-α and their adhesion to fibronectin. Approximately half (29/55) of genes differentially expressed in CTCs were prognostic in patients with newly-diagnosed myeloma (n = 553; CoMMpass). In a multivariate analysis including the R-ISS, overexpression of CENPF and LGALS1 was significantly associated with inferior survival. Altogether, these results help understanding the presence of CTCs in PB and suggest that hypoxic BM niches together with a pro-inflammatory microenvironment induce an arrest in proliferation, forcing tumor cells to circulate in PB and seek other BM niches to continue growing.

Targeting tumor phenotypic plasticity and metabolic remodeling in adaptive cross-drug tolerance

Metastable phenotypic state transitions in cancer cells can lead to the development of transient adaptive resistance or tolerance to chemotherapy. Here, we report that the acquisition of a phenotype marked by increased abundance of CD44 (CD44^Hi) by breast cancer cells as a tolerance response to routinely used cytotoxic drugs, such as taxanes, activated a metabolic switch that conferred tolerance against unrelated standard-of-care chemotherapeutic agents, such as anthracyclines. We characterized the sequence of molecular events that connected the induced CD44^Hi phenotype to increased activity of both the glycolytic and oxidative pathways and glucose flux through the pentose phosphate pathway (PPP). When given in a specific order, a combination of taxanes, anthracyclines, and inhibitors of glucose-6-phosphate dehydrogenase (G6PD), an enzyme involved in glucose metabolism, improved survival in mouse models of breast cancer. The same sequence of the three-drug combination reduced the viability of patient breast tumor samples in an explant system. Our findings highlight a convergence between phenotypic and metabolic state transitions that confers a survival advantage to cancer cells against clinically used drug combinations. Pharmacologically targeting this convergence could overcome cross-drug tolerance and could emerge as a new paradigm in the treatment of cancer.

Perspectives for Ezrin and Radixin in Astrocytes: Kinases, Functions and Pathology

Astrocytes are increasingly perceived as active partners in physiological brain function and behaviour. The structural correlations of the glia–synaptic interaction are the peripheral astrocyte processes (PAPs), where ezrin and radixin, the two astrocytic members of the ezrin-radixin-moesin (ERM) family of proteins are preferentially localised. While the molecular mechanisms of ERM (in)activation appear universal, at least in mammalian cells, and have been studied in great detail, the actual ezrin and radixin kinases, phosphatases and binding partners appear cell type specific and may be multiplexed within a cell. In astrocytes, ezrin is involved in process motility, which can be stimulated by the neurotransmitter glutamate, through activation of the glial metabotropic glutamate receptors (mGluRs) 3 or 5. However, it has remained open how this mGluR stimulus is transduced to ezrin activation. Knowing upstream signals of ezrin activation, ezrin kinase(s), and membrane-bound binding partners of ezrin in astrocytes might open new approaches to the glial role in brain function. Ezrin has also been implicated in invasive behaviour of astrocytomas, and glial activation. Here, we review data pertaining to potential molecular interaction partners of ezrin in astrocytes, with a focus on PKC and GRK2, and in gliomas and other diseases, to stimulate further research on their potential roles in glia-synaptic physiology and pathology.

The interaction of lncRNA EZR-AS1 with SMYD3 maintains overexpression of EZR in ESCC cells

EZR, a member of the ezrin-radixin-moesin (ERM) family, is involved in multiple aspects of cell migration and cancer. SMYD3, a histone H3–lysine 4 (H3–K4)-specific methyltransferase, regulates EZR gene transcription, but the molecular mechanisms of epigenetic regulation remain ill-defined. Here, we show that antisense lncRNA EZR-AS1 was positively correlated with EZR expression in both human esophageal squamous cell carcinoma (ESCC) tissues and cell lines. Both in vivo and in vitro studies revealed that EZR-AS1 promoted cell migration through up-regulation of EZR expression. Mechanistically, antisense lncRNA EZR-AS1 formed a complex with RNA polymerase II to activate the transcription of EZR. Moreover, EZR-AS1 could recruit SMYD3 to a binding site, present in a GC-rich region downstream of the EZR promoter, causing the binding of SMYD3 and local enrichment of H3K4me3. Finally, the interaction of EZR-AS1 with SMYD3 further enhanced EZR transcription and expression. Our findings suggest that antisense lncRNA EZR-AS1, as a member of an RNA polymerase complex and through enhanced SMYD3-dependent H3K4 methylation, plays an important role in enhancing transcription of the EZR gene to promote the mobility and invasiveness of human cancer cells.

Inhibition of Ezrin suppresses cell migration and invasion in human nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is one of the most severe types of malignant cancer of the head and neck as it is difficult to treat. Ezrin is highly expressed in numerous types of cancer. However, the role of Ezrin in NPC has not been fully investigated and further studies are required in order to uncover its therapeutic potential in the treatment of NPC. The aim of the present study was to investigate the expression of Ezrin in human NPC and to evaluate the effect of knockdown of Ezrin using small interfering (si)-RNA on NPC cell migration and invasion. The expression levels of Ezrin were determined using reverse transcription-quantitative polymerase chain reaction, immunohistochemical staining and western blotting. Following transfection of Ezrin-siRNA into NPC cells, cell invasion and migration were analyzed and the mRNA expression levels of matrix metalloproteinase(MMP)-2 and MMP9 were determined. The results revealed that the expression of Ezrin was markedly increased in human NPC tissue samples compared with normal adjacent nasopharyngeal tissue samples. Ezrin was also highly expressed in the NPC cell lines 6-10B and C6661 when compared with the normal nasopharyngeal cell line NP69. Transfection of NPC cell lines with siRNA targeting Ezrin significantly inhibited NPC cell migration and invasion, and downregulated the mRNA expression level of MMP2; however, no effect was observed on MMP9 mRNA expression. At the same time, knockdown of Ezrin significantly decreased the expression levels of phosphatidylinositol 3-kinase (PI3K) and phosphorylated protein kinase B (Akt), which downregulated the mRNA expression of MMP2. In conclusion, the results revealed that knockdown of Ezrin suppressed NPC migration and invasion by reducing the mRNA expression of MMP2 via the PI3K/Akt signaling pathway. These results highlight the important role of Ezrin in NPC cell migration and invasion. In addition, they indicate that silencing of Ezrin may serve as a potential therapeutic strategy to treat human NPC.

MicroRNA Dysregulation in Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (CSCC) is the second most frequent cancer in humans and it can be locally invasive and metastatic to distant sites. MicroRNAs (miRNAs or miRs) are endogenous, small, non-coding RNAs of 19–25 nucleotides in length, that are involved in regulating gene expression at a post-transcriptional level. MicroRNAs have been implicated in diverse biological functions and diseases. In cancer, miRNAs can proceed either as oncogenic miRNAs (onco-miRs) or as tumor suppressor miRNAs (oncosuppressor-miRs), depending on the pathway in which they are involved. Dysregulation of miRNA expression has been shown in most of the tumors evaluated. MiRNA dysregulation is known to be involved in the development of cutaneous squamous cell carcinoma (CSCC). In this review, we focus on the recent evidence about the role of miRNAs in the development of CSCC and in the prognosis of this form of skin cancer.

Novel CD44-downstream signaling pathways mediating breast tumor invasion

CD44, also known as homing cell adhesion molecule is a multi-structural cell molecule involved in cell-cell and cell-extracellular matrix communications. CD44 regulates a number of central signaling pathways, including PI3K/AKT, Rho GTPases and the Ras-MAPK pathways, but also acts as a growth/arrest sensor, and inhibitor of angiogenesis and invasion, in response to signals from the microenvironment. The function of CD44 has been very controversial since it acts as both, a suppressor and a promoter of tumor growth and progression. To address this discrepancy, we have previously established CD44-inducible system both in vitro and in vivo. Next, using microarray analysis, we have identified and validated Survivin, Cortactin and TGF-β2 as novel CD44-downstream target genes, and characterized their signaling pathways underpinning CD44-promoted breast cancer (BC) cell invasion. This report aims to update the literature by adding and discussing the impact of these novel three signaling pathways to better understand the CD44-signaling pathways involved in BC tumor cell invasion.

A novel monoclonal antibody KMP1 has potential antitumor activity of bladder cancer by blocking CD44 in vivo and in vitro

Bladder cancer becomes a serious medical and social concern due to its high recurrence and mortality rates. Thus, it is urgent to search a novel prognostic biomarker and targeted therapy with high sensitivity and specificity. In this study, we used the human bladder cancer cell line EJ as an immunogen to generate a novel mouse monoclonal antibody KMP1 that specifically bound to bladder cancer, and then, the antitumor effect of KMP1 against bladder cancer was investigated both in vivo and in vitro. The results showed that expression of the KMP1 epitope is consistent with clinical severity and prognosis of bladder cancer. Furthermore, KMP1 not only significantly inhibited the proliferation, migration, and adhesion of EJ cells in vivo, but also suppressed the xenograft tumor growth in nude mice compared with the control group treated with mIgG. Subsequently, the underlying mechanism of KMP1 against bladder cancer was explored via antigen affinity chromatography and mass spectrometry. CD44 located on the cytomembrane was found as the antigen of KMP1. Using RNA interference technology to knock down CD44 expression, we further identified that KMP1 has the antitumor activity by binding to CD44 and blocking its functions. In conclusion, KMP1 might be valuable for development as a promising specific diagnostic biomarker or targeted agent for bladder cancer.

Forecast of actin-binding proteins as the oncotarget in osteosarcoma - a review of mechanism, diagnosis and therapy

Osteosarcoma (OS) is the most common bone malignant tumor with a high rate of lung metastasis and principally emerges in children and adolescents. Although neoadjuvant chemotherapy is widely used around the world, a high rate of chemoresistance occurs and frequently generates a poor prognosis. Therefore, finding a new appropriate prognostic marker for OS is a valuable research direction, which will give patients a better chance to receive proper therapy. Actin-binding proteins (ABPs) are a group of proteins that interact with actin cytoskeleton and play a crucial role in the regulation of the cell motility and morphology in eukaryotes. Meanwhile, ABPs also act as a bridge between the cytomembrane and nucleus, which transmit the outside-in and inside-out signals in cytoplasm. Furthermore, ABPs alter the dynamic structure of actin and regulate the invasion and metastasis of cancer. Hence, ABPs have a wide application in predicting the prognosis, and may be new targets, in tumor therapy. This review focuses on a series of ABPs and discusses their modulatory functions. It provides a new insight into the classification of ABPs’ functions in the process of invasion and metastasis in OS and illuminates the potential ability in predicting the prognosis of OS patients.

LPA-induced migration of ovarian cancer cells requires activation of ERM proteins via LPA1 and LPA2

Lysophosphatidic acid (LPA) has been implicated in the pathology of human ovarian cancer. This phospholipid elicits a wide range of cancer cell responses, such as proliferation, trans-differentiation, migration, and invasion, via various G-protein-coupled LPA receptors (LPARs). Here, we explored the cellular signaling pathway via which LPA induces migration of ovarian cancer cells. LPA induced robust phosphorylation of ezrin/radixin/moesin (ERM) proteins, which are membrane-cytoskeleton linkers, in the ovarian cancer cell line OVCAR-3. Among the LPAR subtypes expressed in these cells, LPA₁ and LPA₂, but not LPA₃, induced phosphorylation of ERM proteins at their C-termini. This phosphorylation was dependent on the Gα_12/13/RhoA pathway, but not on the Gα_q/Ca²⁺/PKC or Gα_s/adenylate cyclase/PKA pathway. The activated ERM proteins mediated cytoskeletal reorganization and formation of membrane protrusions in OVCAR-3 cells. Importantly, LPA-induced migration of OVCAR-3 cells was completely abolished not only by gene silencing of LPA₁ or LPA₂, but also by overexpression of a dominant negative ezrin mutant (ezrin-T567A). Taken together, this study demonstrates that the LPA₁/LPA₂/ERM pathway mediates LPA-induced migration of ovarian cancer cells. These findings may provide a potential therapeutic target to prevent metastatic progression of ovarian cancer.

CD44/CD44v6 a Reliable Companion in Cancer-Initiating Cell Maintenance and Tumor Progression

Metastasis is the leading cause of cancer death, tumor progression proceeding through emigration from the primary tumor, gaining access to the circulation, leaving the circulation, settling in distant organs and growing in the foreign environment. The capacity of a tumor to metastasize relies on a small subpopulation of cells in the primary tumor, so called cancer-initiating cells (CIC). CIC are characterized by sets of markers, mostly membrane anchored adhesion molecules, CD44v6 being the most frequently recovered marker. Knockdown and knockout models accompanied by loss of tumor progression despite unaltered primary tumor growth unraveled that these markers are indispensable for CIC. The unexpected contribution of marker molecules to CIC-related activities prompted research on underlying molecular mechanisms. This review outlines the contribution of CD44, particularly CD44v6 to CIC activities. A first focus is given to the impact of CD44/CD44v6 to inherent CIC features, including the crosstalk with the niche, apoptosis-resistance, and epithelial mesenchymal transition. Following the steps of the metastatic cascade, we report on supporting activities of CD44/CD44v6 in migration and invasion. These CD44/CD44v6 activities rely on the association with membrane-integrated and cytosolic signaling molecules and proteases and transcriptional regulation. They are not restricted to, but most pronounced in CIC and are tightly regulated by feedback loops. Finally, we discuss on the engagement of CD44/CD44v6 in exosome biogenesis, loading and delivery. exosomes being the main acteurs in the long-distance crosstalk of CIC with the host. In brief, by supporting the communication with the niche and promoting apoptosis resistance CD44/CD44v6 plays an important role in CIC maintenance. The multifaceted interplay between CD44/CD44v6, signal transducing molecules and proteases facilitates the metastasizing tumor cell journey through the body. By its engagement in exosome biogenesis CD44/CD44v6 contributes to disseminated tumor cell settlement and growth in distant organs. Thus, CD44/CD44v6 likely is the most central CIC biomarker.

Determination of brain injury biomarkers by surface-enhanced Raman scattering using hollow gold nanospheres

The development of rapid, highly sensitive detection methods for neuron-specific enolase (NSE) and S100-β protein is very important as the levels of NSE and S100-β protein in the blood are closely related to brain injury.

Synthetic 8-hydroxydeoxyguanosine inhibited metastasis of pancreatic cancer through concerted inhibitions of ERM and Rho-GTPase

8-hydroxydeoxyguanosine (8-OHdG) is generated consequent to oxidative stress, but its paradoxical anti-oxidative, anti-inflammatory, and anti-mutagenic effects via Rho-GTPase inhibition were noted in various models of inflammation and cancer. Metastasis occurs through cell detachment, epithelial-mesenchymal transition (EMT), and cell migration; during these processes, changes in cell morphology are initiated through Rho-GTPase-dependent actin cytoskeleton polymerization. In this study, we explored the anti-metastatic mechanisms of 8-OHdG in Panc-1 pancreatic cancer cells. 8-OHdG inhibits cell migration by inactivating ERM and Rho-GTPase proteins, and inhibiting focal adhesion kinase (FAK) and matrix metalloproteinases (MMPs). At 15min, 8-OHdG significantly inactivated ERM (p < 0.05) and led to a significant retardation of wound healing; siERM and H1152 (ROCK inhibitor) had similar effects (p < 0.05). However, FAK inhibitor 14, DPI (NOX inhibitor), and NAC (antioxidant) significantly delayed wound healing without inhibiting ERM or CD44 (p < 0.05). In the experiments on cell migration, siERM, siCD44, DPI, and 8-OHdG significantly inhibited MMPs. 8-OHdG significantly decreased DCF-DA activation in Panc-1 pancreatic cancer cells and down-regulated NOXs (nox-1, nox-2, and nox-3). Finally, all of these anti-migration actions of 8-OHdG resulted in significant inhibition of EMT, as evidenced by the up-regulation of ZO-1 and claudin-1 and down-regulation of vimentin. We found significant inhibition of lung metastasis of Panc-1 cells by 8-OHdG. In conclusion, exogenous 8-OHdG had potent anti-metastasis effects mediated by either ERM or Rho GTPase inhibition in metastasis-prone pancreatic cancer cells.

Effects of Prisma® Skin dermal regeneration device containing glycosaminoglycans on human keratinocytes and fibroblasts

Prisma® Skin is a new pharmaceutical device developed by Mediolanum Farmaceutici S.p.a. It includes alginates, hyaluronic acid and mainly mesoglycan. The latter is a natural glycosaminoglycan preparation containing chondroitin sulfate, dermatan sulfate, heparan sulfate and heparin and it is used in the treatment of vascular disease. Glycosaminoglycans may contribute to the re-epithelialization in the skin wound healing, as components of the extracellular matrix. Here we describe, for the first time, the effects of Prisma® Skin in in vitro cultures of adult epidermal keratinocytes and dermal fibroblasts. Once confirmed the lack of cytotoxicity by mesoglycan and Prisma® Skin, we have shown the increase of S and G2 phases of fibroblasts cell cycle distribution. We further report the strong induction of cell migration rate and invasion capability on both cell lines, two key processes of wound repair. In support of these results, we found significant cytoskeletal reorganization, following the treatments with mesoglycan and Prisma® Skin, as confirmed by the formation of F-actin stress fibers. Additionally, together with a significant reduction of E-cadherin, keratinocytes showed an increase of CD44 expression and the translocation of ezrin to the plasma membrane, suggesting the involvement of CD44/ERM (ezrin-radixin-moesin) pathway in the induction of the analyzed processes. Furthermore, as showed by immunofluorescence assay, fibroblasts treated with mesoglycan and Prisma® Skin exhibited the increase of Fibroblast Activated Protein α and a remarkable change in shape and orientation, two common features of reactive stromal fibroblasts. In all experiments Prisma® Skin was slightly more potent than mesoglycan. In conclusion, based on these findings we suggest that Prisma® Skin may be able to accelerate the healing process in venous skin ulcers, principally enhancing re-epithelialization and granulation processes.

Ezrin interacts with S100A4 via both its N- and C-terminal domains

Ezrin belongs to the ERM (ezrin, radixin, moesin) protein family that has a role in cell morphology changes, adhesion and migration as an organizer of the cortical cytoskeleton by linking actin filaments to the apical membrane of epithelial cells. It is highly expressed in a variety of human cancers and promotes metastasis. Members of the Ca2+-binding EF-hand containing S100 proteins have similar pathological properties; they are overexpressed in cancer cells and involved in metastatic processes. In this study, using tryptophan fluorescence and stopped-flow kinetics, we show that S100A4 binds to the N-terminal ERM domain (N-ERMAD) of ezrin with a micromolar affinity. The binding involves the F2 lobe of the N-ERMAD and follows an induced fit kinetic mechanism. Interestingly, S100A4 binds also to the unstructured C-terminal actin binding domain (C-ERMAD) with similar affinity. Using NMR spectroscopy, we characterized the complex of S100A4 with the C-ERMAD and demonstrate that no ternary complex is simultaneously formed with the two ezrin domains. Furthermore, we show that S100A4 co-localizes with ezrin in HEK-293T cells. However, S100A4 very weakly binds to full-length ezrin in vitro indicating that the interaction of S100A4 with ezrin requires other regulatory events such as protein phosphorylation and/or membrane binding, shifting the conformational equilibrium of ezrin towards the open state. As both proteins play an important role in promoting metastasis, the characterization of their interaction could shed more light on the molecular events contributing to this pathological process.

Hyaluronan synthesis by developing cortical neurons in vitro

Hyaluronan is a linear glycosaminoglycan that forms the backbone of perineuronal nets around neurons in the cerebral cortex. However, it remains controversial whether neurons are capable of independent hyaluronan synthesis. Herein, we examined the expression of hyaluronan and hyaluronan synthases (HASs) throughout cortical neuron development in vitro. Enriched cultures of cortical neurons were established from E16 rats. Neurons were collected at days in vitro (DIV) 0 (4 h), 1, 3, 7, 14, and 21 for qPCR or immunocytochemistry. In the relative absence of glia, neurons exhibited HAS1–3 mRNA at all time-points. By immunocytochemistry, puncta of HAS2–3 protein and hyaluronan were located on neuronal cell bodies, neurites, and lamellipodia/growth cones from as early as 4 h in culture. As neurons matured, hyaluronan was also detected on dendrites, filopodia, and axons, and around synapses. Percentages of hyaluronan-positive neurons increased with culture time to ~93% by DIV21, while only half of neurons at DIV21 expressed the perineuronal net marker Wisteria floribunda agglutinin. These data clearly demonstrate that neurons in vitro can independently synthesise hyaluronan throughout all maturational stages, and that hyaluronan production is not limited to neurons expressing perineuronal nets. The specific structural localisation of hyaluronan suggests potential roles in neuronal development and function.

Similar expression pattern of NHERF1 and EZRIN in papillary but not in solid areas of human serous ovarian carcinomas

NHERF1 is an adaptor protein expressed in the apical membrane of polarized epithelia, which interacts with the EZRIN-Radixin-Moesin (ERM) family of proteins connecting signaling pathways to the cell cytoskeleton. NHERF1 and EZRIN cooperate in the maintenance of the apical microvilli in polarized epithelial cells. In several types of cancers, NHERF1 and EZRIN are displaced from the apical compartment to the cytoplasm and nuclei of cancer cells. At the present, the distribution of NHERF1 in ovarian tumors is not well known. In this study, NHERF1 expression was examined by immunohistochemistry in cyst adenofibromas, serous borderline tumors, and serous ovarian carcinomas. We observed a strong staining of NHERF1 and EZRIN at the membrane level of borderline tumors and areas of papillary structures in ovarian carcinomas. In tumors without papillary structures and compact structure, NHERF1 was exclusively expressed in the apical pole of the cells at the edges of the clefts of luminal spaces. In contrast, positive expression of EZRIN was found in the membrane of tumor cells within the solid tumor where NHERF1 was not expressed. In summary, this study shows, for the first time, the distribution of NHERF1 in ovarian cancer and reveals a different regulation of NHERF1 and EZRIN expression in ovarian tumors which represents the complexity of the molecular changes of this disease.

Expression of Ezrin and Estrogen Receptors During Cervical Carcinogenesis

RATIONALE

Development of cervical squamous carcinoma (CXCA) is accompanied by changes in estrogen receptors (ERs, ERα and ERβ) and ezrin expression; however, reports have been conflicting. Using histologically documented staging of cervical biopsies, we determined ezrin and ER relationships during CXCA development.

METHODS

Immunoreactive (ir) ezrin, ir-ERα, and ir-ERβ were studied in normal epithelium, carcinoma in situ/cervical intraepithelial neoplasia (CIN) 1 to 3, and local invasion or metastatic CXCA. Results were compared using H scoring. Cultures of Caski metastatic CXCA cells were treated with estradiol and/or tamoxifen and studied for ER-driven ir-ezrin and the morphologic response.

RESULTS

Koilocytosis was present and indicated viral presence. The ezrin H score increased from CIN1 to CIN3, reaching significant differences from normal by CIN3 ( P = .004) and 2× normal in metastatic CXCA. Estrogen receptor α and ERβ H scores fell, reaching significance by CIN3 (ERα, P = .0001; ERβ, P = .024). During estradiol treatment, ezrin in Caski cells increased and localized to the periphery, in ruffles and processes. The selective ER modulator tamoxifen blocked the estradiol-induced changes.

CONCLUSIONS

During cervical carcinogenesis, the usual relationship between estrogen and ezrin induction is abridged. This is consistent with the effects of human papilloma virus viral proteins such as E6 and E7 that upregulate SIX1, a protein that induces ezrin. Cervical carcinogenesis is progressive but arrests at the preinvasive stage for varying lengths of time. These studies suggest that changes in ezrin may be associated with the development of the invasive phenotype and penetration of the basement membrane. They also raise the possibility that inhibiting ezrin expression could be a target for the prevention of invasive CXCA.

Establishment and Characterization of a Human Small Cell Osteosarcoma Cancer Stem Cell Line: A New Possible In Vitro Model for Discovering Small Cell Osteosarcoma Biology

Osteosarcoma (OSA) is the most common primary malignant bone tumor, usually arising in the long bones of children and young adults. There are different subtypes of OSA, among which we find the conventional OS (also called medullary or central osteosarcoma) which has a high grade of malignancy and an incidence of 80%. There are different subtypes of high grade OS like chondroblastic, fibroblastic, osteoblastic, telangiectatic, and the small cell osteosarcoma (SCO). In this study, for the first time, we have isolated, established, and characterized a cell line of cancer stem cells (CSCs) from a human SCO. First of all, we have established a primary finite cell line of SCO, from which we have isolated the CSCs by the sphere formation assay. We have proved their in vitro mesenchymal and embryonic stem phenotype. Additionally, we have showed their neoplastic phenotype, since the original tumor bulk is a high grade osteosarcoma. This research demonstrates the existence of CSCs also in human primary SCO and highlights the establishment of this particular stabilized cancer stem cell line. This will represent a first step into the study of the biology of these cells to discover new molecular targets molecules for new incisive therapeutic strategies against this highly aggressive OSA.

The Importance of CD44 as a Stem Cell Biomarker and Therapeutic Target in Cancer

CD44 is a cell surface HA-binding glycoprotein that is overexpressed to some extent by almost all tumors of epithelial origin and plays an important role in tumor initiation and metastasis. CD44 is a compelling marker for cancer stem cells of many solid malignancies. In addition, interaction of HA and CD44 promotes EGFR-mediated pathways, consequently leading to tumor cell growth, tumor cell migration, and chemotherapy resistance in solid cancers. Accumulating evidence indicates that major HA-CD44 signaling pathways involve a specific variant of CD44 isoforms; however, the particular variant almost certainly depends on the type of tumor cell and the stage of the cancer progression. Research to date suggests use of monoclonal antibodies against different CD44 variant isoforms and targeted inhibition of HA/CD44-mediated signaling combined with conventional radio/chemotherapy may be the most favorable therapeutic strategy for future treatments of advanced stage malignancies. Thus, this paper briefly focuses on the association of the major CD44 variant isoforms in cancer progression, the role of HA-CD44 interaction in oncogenic pathways, and strategies to target CD44-overexpressed tumor cells.

NGF-induced TrkA/CD44 association is involved in tumor aggressiveness and resistance to lestaurtinib

There is accumulating evidence that TrkA and its ligand Nerve Growth Factor (NGF) are involved in cancer development. Staurosporine derivatives such as K252a and lestaurtinib have been developed to block TrkA kinase signaling, but no clinical trial has fully demonstrated their therapeutic efficacy. Therapeutic failures are likely due to the existence of intrinsic signaling pathways in cancer cells that impede or bypass the effects of TrkA tyrosine kinase inhibitors. To verify this hypothesis, we combined different approaches including mass spectrometry proteomics, co-immunoprecipitation and proximity ligation assays. We found that NGF treatment induced CD44 binding to TrkA at the plasma membrane and subsequent activation of the p115RhoGEF/RhoA/ROCK1 pathway to stimulate breast cancer cell invasion. The NGF-induced CD44 signaling was independent of TrkA kinase activity. Moreover, both TrkA tyrosine kinase inhibition with lestaurtinib and CD44 silencing with siRNA inhibited cell growth in vitro as well as tumor development in mouse xenograft model; combined treatment significantly enhanced the antineoplastic effects of either treatment alone. Altogether, our results demonstrate that NGF-induced tyrosine kinase independent TrkA signaling through CD44 was sufficient to maintain tumor aggressiveness. Our findings provide an alternative mechanism of cancer resistance to lestaurtinib and indicate that dual inhibition of CD44 and TrkA tyrosine kinase activity may represent a novel therapeutic strategy.

Expression of F-actin-capping protein subunit beta, CAPZB, is associated with cell growth and motility in epithelioid sarcoma

BACKGROUND

A previous proteomics study demonstrated the overexpression of F-actin capping protein subunit beta (CAPZB) in tissue specimens of epithelioid sarcoma (EpiS). The aim of the present study was to elucidate the function of CAPZB in EpiS.

METHODS

Cellular functional assays were performed in two EpiS cell lines using CAPZB siRNAs. In addition, comparative protein expression analyses using Isobaric Tags for Relative and Absolute Quantitation (i-TRAQ) method were performed to identify the specific proteins whose expression was dysregulated by CAPZB, and analysed the data with the Ingenuity Pathways Analysis (IPA) system using the obtained protein profiles to clarify the functional pathway networks associated with the oncogenic function of CAPZB in EpiS. Additionally, we performed functional assays of the INI1 protein using INI1-overexpressing EpiS cells.

RESULTS

All 15 EpiS cases showed an immunohistochemical expression of CAPZB, and two EpiS cell lines exhibited a strong CAPZB expression. Silencing of CAPZB inhibited the growth, invasion and migration of the EpiS cells. Analysis of protein profiles using the IPA system suggested that SWI/SNF chromatin-remodeling complexes including INI1 may function as a possible upstream regulator of CAPZB. Furthermore, silencing of CAPZB resulted in a decreased expression of INI1 proteins in the INI1-positive EpiS cells, whereas the induction of INI1 in the INI1-deficient EpiS cells resulted in an increased CAPZB mRNA expression.

CONCLUSIONS

CAPZB is involved in tumor progression in cases of EpiS, irrespective of the INI1 expression, and may be a potential therapeutic target. The paradoxical relationship between the tumor suppressor INI1 and the oncoprotein CAPZB in the pathogenesis of EpiS remains to be clarified.