Cadherins as novel targets for anti-cancer therapy

Electromagnetic field as a possible inhibitor of tumor invasion by declining E-cadherin/N-cadherin switching in triple negative breast cancer

Breast cancer has been recognized as the most common cancer affecting women. Extremely low-frequency electromagnetic field (ELF-EMF) exposure can influence cellular activities such as cell-cell junctions and metastasis. However, more research is required to determine these fields' underlying mechanisms of action. Since cadherin switching is an important process during EMT (epithelial-mesenchymal transition), in this study, cadherin switching was regarded as one of the probable mechanisms of the effect of ELF-EMFs on metastasis suppression. For five days, breast cells received a 1 Hz, 100mT ELF-EMF (2 h/day). Cell invasion and migration were assessed in vitro by the Scratch wound healing assay and Transwell culture chambers. The expression of E- and N-cadherin was assessed using real-time PCR, western blotting, and Immunocytochemistry. ELF-EMF dramatically reduced the migration and invasion of MDA-MB 231 malignant cells compared to sham exposure, according to the results of the scratch test and the Transwell invasion test. The mRNA and protein expression levels of E-cadherin showed an increase, while the N-cadherin expression was found with a decrease, in MDA-MB231 cells receiving 1 Hz EMF compared to sham exposure. E-cadherin's mRNA and protein expression levels were enhanced in MCF10A cells receiving 1 Hz EMF compared to sham exposure. ELF-EMF can be used as a method for the multifaceted treatments of invasive breast cancer.

A SIRT6 Inhibitor, Marine-Derived Pyrrole-Pyridinimidazole Derivative 8a, Suppresses Angiogenesis

Angiogenesis refers to the process of growing new blood vessels from pre-existing capillaries or post-capillary veins. This process plays a critical role in promoting tumorigenesis and metastasis. As a result, developing antiangiogenic agents has become an attractive strategy for tumor treatment. Sirtuin6 (SIRT6), a member of nicotinamide adenine (NAD+)-dependent histone deacetylases, regulates various biological processes, including metabolism, oxidative stress, angiogenesis, and DNA damage and repair. Some SIRT6 inhibitors have been identified, but the effects of SIRT6 inhibitors on anti-angiogenesis have not been reported. We have identified a pyrrole-pyridinimidazole derivative 8a as a highly effective inhibitor of SIRT6 and clarified its anti-pancreatic-cancer roles. This study investigated the antiangiogenic roles of 8a. We found that 8a was able to inhibit the migration and tube formation of HUVECs and downregulate the expression of angiogenesis-related proteins, including VEGF, HIF-1α, p-VEGFR2, and N-cadherin, and suppress the activation of AKT and ERK pathways. Additionally, 8a significantly blocked angiogenesis in intersegmental vessels in zebrafish embryos. Notably, in a pancreatic cancer xenograft mouse model, 8a down-regulated the expression of CD31, a marker protein of angiogenesis. These findings suggest that 8a could be a promising antiangiogenic and cancer therapeutic agent.

Cell Adhesion Molecules in Neuroblastoma: Complex Roles, Therapeutic Potential

Neuroblastoma, a biologically heterogeneous tumor derived from neural crest cells, accounts for approximately 15% of childhood deaths from cancer. Recently, scientific literature has explored the role of cell adhesion molecules (CAMs) in cancer metastasis through cell detachment, migration, and invasion. Through a review of the current literature, it is evident that expression of different CAMs on neuroblastoma tumors is associated with favorable or unfavorable clinical prognosis. In patients diagnosed with neuroblastoma, treatment strategies include chemotherapy, surgery, radiotherapy, stem cell transplant, and more recently, immunotherapy and other targeted therapies. Long term survival remains poor despite multimodality treatment, especially for children with high-risk neuroblastoma, making it more necessary to explore innovative targeted therapies. CAMs have immense potential as therapeutic targets, but there is a need for growth and scientific exploration before CAM therapies become clinically useful.

Potential Therapeutic Applications of N-Cadherin Antagonists and Agonists

This review focuses on the cell adhesion molecule (CAM), known as neural (N)-cadherin (CDH2). The molecular basis of N-cadherin-mediated intercellular adhesion is discussed, as well as the intracellular signaling pathways regulated by this CAM. N-cadherin antagonists and agonists are then described, and several potential therapeutic applications of these intercellular adhesion modulators are considered. The usefulness of N-cadherin antagonists in treating fibrotic diseases and cancer, as well as manipulating vascular function are emphasized. Biomaterials incorporating N-cadherin modulators for tissue regeneration are also presented. N-cadherin antagonists and agonists have potential for broad utility in the treatment of numerous maladies.

Cell Plasticity and Prostate Cancer: The Role of Epithelial-Mesenchymal Transition in Tumor Progression, Invasion, Metastasis and Cancer Therapy Resistance

Simple Summary

Although epithelial-to-mesenchymal transition (EMT) is a well-known cellular process involved during normal embryogenesis and wound healing, it also has a dark side; it is a complex process that provides tumor cells with a more aggressive phenotype, facilitating tumor metastasis and even resistance to therapy. This review focuses on the key pathways of EMT in the pathogenesis of prostate cancer and the development of metastases and evasion of currently available treatments.

Abstract

Prostate cancer, the second most common malignancy in men, is characterized by high heterogeneity that poses several therapeutic challenges. Epithelial–mesenchymal transition (EMT) is a dynamic, reversible cellular process which is essential in normal embryonic morphogenesis and wound healing. However, the cellular changes that are induced by EMT suggest that it may also play a central role in tumor progression, invasion, metastasis, and resistance to current therapeutic options. These changes include enhanced motility and loss of cell–cell adhesion that form a more aggressive cellular phenotype. Moreover, the reverse process (MET) is a necessary element of the metastatic tumor process. It is highly probable that this cell plasticity reflects a hybrid state between epithelial and mesenchymal status. In this review, we describe the underlying key mechanisms of the EMT-induced phenotype modulation that contribute to prostate tumor aggressiveness and cancer therapy resistance, in an effort to provide a framework of this complex cellular process.

N-cadherin inhibitor creates a microenvironment that protect TILs from immune checkpoints and Treg cells

BACKGROUND

Few patients with prostate cancer benefit from current immunotherapies. Therefore, we aimed to explore new strategies to change this paradigm.

METHODS

Human tissues, cell lines and in vivo experiments were used to determine whether and how N-cadherin impacts the production of programmed death ligand-1 (PD-L1) and indole amine 2,3-dioxygenase (IDO-1) and whether N-cadherin can increase the production of effector (e)Treg cells. Then, we used PC3-bearing humanized non-obese diabetic/severe combined immunodeficiency IL2Rγnull (hNSG) mice with an intravenous injection of human CD34+ hematopoietic stem cells into the tail vein to evaluate whether the N-cadherin antagonist N-Ac-CHAVC-NH2 (designated ADH-1) could improve the therapeutic effect of tumor-infiltrating lymphocyte (TIL)-related treatment.

RESULTS

N-cadherin dramatically upregulated the expression of PD-L1 and IDO-1 through IFN-γ (interferongamma) signaling and increasing the production of free fatty acids that could promote the generation of eTreg cells. In preclinical experiments, immune reconstitution mediated by TILs slowed tumor growth and extended the survival time; however, this effect disappeared after immune system suppression by PD-L1, IDO-1 and eTreg cells. Furthermore, ADH-1 effectively reduced immunosuppression and enhanced TIL-related therapy.

CONCLUSIONS

These data show that the N-cadherin antagonist ADH-1 promotes TIL antitumor responses. This important hurdle must be overcome for tumors to respond to immunotherapy.

Cry1A Proteins are Cytotoxic to HeLa but not to SiHa Cervical Cancer Cells

BACKGROUND

Bacillus thuringiensis toxins are effective against multiple biological targets such as insects, nematodes, mites, protozoa, and importantly, human cancer cells. One of the main mechanisms by which Cry toxins to trigger cell death is the specific recognition of cadherin-like membrane cell receptors.

OBJECTIVE

This work aimed to assess the cytotoxicity of the Cry1Ab and Cry1Ac toxins from Bacillus thuringiensis in HeLa, cervical cancer cell line, as well as their antitumor activity in mouse models.

METHODS

We analyzed several biological targets of Cry1Ab and Cry1Ac including erythrocytes, insect larvae, as well as cancer and non-cancer cell lines. The viability of HeLa, SiHa, MCF7 and HaCat cells was assessed by MTT 24 h after the administration of Cry toxins. We also studied apoptosis as a possible cytotoxicity mechanism in HeLa. The capacity of Cry toxins to eliminate tumors in xenograft mouse models was also analyzed.

RESULTS

Both toxins, Cry1Ab and Cry1Ac, showed specific cytotoxic activity in HeLa (HPV18+) cervical cancer cell line, with a Cry1Ab LC50 of 2.5 µg/ml, and of 0.5 µg/ml for Cry1Ac. Apoptosis was differentially induced in HeLa cells using the same concentration of Cry1Ab and Cry1Ac toxins. Cry1Ac eliminated 50% of the tumors at 10 µg/ml, and eliminate 100% of the tumors at 30 and 50 µg/ml.

CONCLUSION

Bacillus thuringiensis Cry1A toxins show dual cytotoxic activity, in insects as well as in HeLa cancer cell line.

Cancer invasion regulates vascular complexity in a three-dimensional biomimetic model

INTRODUCTION

There is a growing appreciation for including a complex, vascularised stroma in three-dimensional (3D) tumour models to recapitulate the native tumour microenvironment in situ.

METHODS

Using a compartmentalised, biomimetic, 3D cancer model, comprising a central cancer mass surrounded by a vascularised stroma, we have tested the invasive capability of colorectal cancer cells.

RESULTS

We show histological analysis of dense collagen I/laminin scaffolds, forming necrotic cores with cellular debris. Furthermore, cancer cells within this 3D matrix form spheroids, which is corroborated with high EpCAM expression. We validate the invasive growth of cancer cells into the stroma through quantitative image analysis and upregulation of known invasive gene markers, including metastasis associated in colon cancer 1, matrix metalloproteinase 7 and heparinase. Tumouroids containing highly invasive HCT116 cancer masses form less complex and less branched vascular networks, recapitulating 'leaky' vasculature associated with highly metastatic cancers. Angiogenic factors regulating this were vascular endothelial growth factor A and hepatocyte growth factor active protein. Where vascular networks were formed with less invasive cancer masses (HT29), higher expression of vascular endothelial cadherin active protein resulted in more complex and branched networks. To eliminate the cell-cell interaction between the cancer mass and stroma, we developed a three-compartment model containing an acellular ring to test the chemoattractant pull from the cancer mass. This resulted in migration of endothelial networks through the acellular ring accompanied by alignment of vascular networks at the cancer/stroma boundary.

DISCUSSION

This work interrogates to the gene and protein level how cancer cells influence the development of a complex stroma, which shows to be directly influenced by the invasive capability of the cancer.

Structure-Based Virtual Screening Allows the Identification of Efficient Modulators of E-Cadherin-Mediated Cell-Cell Adhesion

Cadherins are a large family of transmembrane calcium-dependent cell adhesion proteins that orchestrate adherens junction formation and are crucially involved in tissue morphogenesis. Due to their important role in cancer development and metastasis, cadherins can be considered attractive targets for drug discovery. A recent crystal structure of the complex of a cadherin extracellular portion and a small molecule inhibitor allowed the identification of a druggable interface, thus providing a viable strategy for the design of cadherin dimerization modulators. Here, we report on a structure-based virtual screening approach that led to the identification of efficient and selective modulators of E-cadherin-mediated cell–cell adhesion. Of all the putative inhibitors that were identified and experimentally tested by cell adhesion assays using human pancreatic tumor BxPC-3 cells expressing both E-cadherin and P-cadherin, two compounds turned out to be effective in inhibiting stable cell–cell adhesion at micromolar concentrations. Moreover, at the same concentrations, one of them also showed anti-invasive properties in cell invasion assays. These results will allow further development of novel and selective cadherin-mediated cell–cell adhesion modulators for the treatment of a variety of cadherin-expressing solid tumors and for improving the efficiency of drug delivery across biological barriers.

Differential Expression and Pathway Analysis in Drug-Resistant Triple-Negative Breast Cancer Cell Lines Using RNASeq Analysis

Triple-negative breast cancer (TNBC) is among the most notorious types of breast cancer, the treatment of which does not give consistent results due to the absence of the three receptors (estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) as well as high amount of molecular variability. Drug resistance also contributes to treatment unresponsiveness. We studied differentially expressed genes, their biological roles, as well as pathways from RNA-Seq datasets of two different TNBC drug-resistant cell lines of Basal B subtype SUM159 and MDA-MB-231 treated with drugs JQ1 and Dexamethasone, respectively, to elucidate the mechanism of drug resistance. RNA sequencing(RNA-Seq) data analysis was done using edgeR which is an efficient program for determining the most significant Differentially Expressed Genes (DEGs), Gene Ontology (GO) terms, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. iPathway analysis was further used to obtain validated results using analysis that takes into consideration type, function, and interactions of genes in the pathway. The significant similarities and differences throw light into the molecular heterogeneity of TNBC, giving clues into the aspects that can be focused to overcome drug resistance. From this study, cytokine-cytokine receptor interaction pathway appeared to be a key factor in TNBC drug resistance.

Upregulated N-cadherin expression is associated with poor prognosis in epithelial-derived solid tumours: A meta-analysis

BACKGROUND

N-cadherin is an important molecular in epithelial-mesenchymal transition (EMT) and has been reported to be associated with aggressive behaviours of tumours. However, prognostic value of N-cadherin in solid malignancies remains controversially.

MATERIALS AND METHODS

The Pubmed/MELINE and EMBASE databases were used for a comprehensive literature searching. Pooled risk ratio (RR) and hazard ratio (HR) with their corresponding 95% confidence intervals (CIs) were employed to quantify the prognostic role.

RESULTS

Involving 36 studies with 5705 patients were performed to investigate relationships between N-cadherin upregulation and clinicopathological features, survival. Results suggested upregulated N-cadherin was associated with lymph node metastasis (RR = 1.16, 95% CI [1.00, 1.35]), higher histological grade (RR = 1.36, 95%CI [1.14, 1.62]), angiolymphatic invasion (RR = 1.19, 95% CI [1.06, 1.34]) and advanced clinical stage (RR = 1.32, 95% CI [1.06, 1.64]), while upregulated N-cadherin was apt to be associated with distant metastasis (RR = 1.43, 95% CI [0.99, 2.05]). Moreover, N-cadherin was correlated with poor prognosis of 3-year survival (HR = 1.78, 95% CI [1.51, 2.10]), 5-year survival (HR = 1.57, 95% CI [1.17, 2.10]) and overall survival (OS) (HR = 1.32, 95% CI [1.20, 1.44]). Subgroup analyses according to cancer types were also conducted for applying these conclusions to some tumours more properly. No publication bias was found except subgroup analysis of distant metastasis (P = .652 for Begg's test and 0.023 for Egger's test).

CONCLUSIONS

Taken together, upregulation of N-cadherin is associated with more aggressive behaviours of epithelial-derived solid malignancies and can be regarded as a predictor of poor survival.

Homeobox B3 promotes tumor cell proliferation and invasion in glioblastoma

Glioblastoma (GBM) is the most aggressive brain tumor in adults with the highest mortality rate. Despite advances achieved in treatment and research, the median survival for patients with GBM remains <1.5 years. This figure prompted the present study to identify novel genes associated with GBM development and progression to ultimately improve GBM treatment. The current study sought to determine the role of homeobox B3 (HOXB3) in GBM cell invasion and proliferation. HOXB3 was highly expressed in GBM tissues and glioma cell lines. To establish in vitro cell models for investigation, U87-MG and U251-MG, two typical GBM cells, were selected to generate corresponding cells lines that constitutively silenced HOXB3 expression using a lentivirus-mediated RNA interference approach. The results of the knockdown revealed that glioma cells stably expressing HOXB3 short hairpin RNA exhibited significantly decreased proliferation levels when compared with untransfected cells. The effect of HOXB3 on glioma cell invasion was also examined. Silencing of HOXB3 resulted in a marked reduction in invasiveness. Furthermore, HOXB3 silencing led to the upregulation of E-cadherin and downregulation of mesenchymal markers, N-cadherin and vimentin. Taken together, the findings of the present study indicate that HOXB3 promotes cell proliferation and invasion.

Deep analysis of N-cadherin/ADH-1 interaction: a computational survey

Due to the considerable role of N-cadherin in cancer metastasis, tumor growth, and progression, inhibition of this protein has been highly regarded in recent years. Although ADH-1 has been known as an appropriate inhibitor of N-cadherin in clinical trials, its chemical nature and binding mode with N-cadherin have not been precisely specified yet. Accordingly, in this study, quantum mechanics calculations were used to investigate the chemical nature of ADH-1. These calculations clarify the molecular properties of ADH-1 and determine its reactive sites. Based on the results, the oxygen atoms are suitable for electrophilic reactivity, while the hydrogen atoms that are connected to nitrogen atoms are the favorite sites for nucleophilic reactivity. The higher electronegativity of the oxygen atoms makes them the most reactive portions in this molecule. Molecular docking and molecular dynamics (MD) simulation have also been applied to specify the binding mode of ADH-1 with N-cadherin and determine the important residues of N-cadherin involving in the interaction with ADH-1. Moreover, the verified model by MD simulation has been studied to extract the free energy value and find driving forces. These calculations and molecular electrostatic potential map of ADH-1 indicated that hydrophobic and electrostatic interactions are almost equally involved in the implantation of ADH-1 in the N-cadherin binding site. The presented results not only enable a closer examination of N-cadherin in complex with ADH-1 molecule, but also are very beneficial in designing new inhibitors for N-cadherin and can help to save time and cost in this field.

Hypoxia activates cadherin-22 synthesis via eIF4E2 to drive cancer cell migration, invasion and adhesion

Hypoxia is a driver of cell movement in processes such as development and tumor progression. The cellular response to hypoxia involves a transcriptional program mediated by hypoxia-inducible factors, but translational control has emerged as a significant contributor. In this study, we demonstrate that a cell-cell adhesion molecule, cadherin-22, is upregulated in hypoxia via mTORC1-independent translational control by the initiation factor eIF4E2. We identify new functions of cadherin-22 as a hypoxia-specific cell-surface molecule involved in cancer cell migration, invasion and adhesion. Silencing eIF4E2 or cadherin-22 significantly impaired MDA-MB-231 breast carcinoma and U87MG glioblastoma cell migration and invasion only in hypoxia, while reintroduction of the respective exogenous gene restored the normal phenotype. Cadherin-22 was evenly distributed throughout spheroids and required for their formation and support of a hypoxic core. Conversely, E-cadherin translation was repressed by hypoxia and only expressed in the oxygenated cells of U87MG spheroids. Furthermore, immunofluorescence on paraffin-embedded human tissue from 40 glioma and 40 invasive ductal breast carcinoma patient specimens revealed that cadherin-22 expression colocalized with areas of hypoxia and significantly correlated with tumor grade and progression-free survival or stage and tumor size, respectively. This study broadens our understanding of tumor progression and metastasis by highlighting cadherin-22 as a potential new target of cancer therapy to disable hypoxic cancer cell motility and adhesion.

Cadherin composition and multicellular aggregate invasion in organotypic models of epithelial ovarian cancer intraperitoneal metastasis

During epithelial ovarian cancer (EOC) progression, intraperitoneally disseminating tumor cells and multi-cellular aggregates (MCAs) present in ascites fluid adhere to the peritoneum and induce retraction of the peritoneal mesothelial monolayer prior to invasion of the collagen-rich sub-mesothelial matrix and proliferation into macro-metastases. Clinical studies have shown heterogeneity among EOC metastatic units with respect to cadherin expression profiles and invasive behavior, however the impact of distinct cadherin profiles on peritoneal anchoring of metastatic lesions remains poorly understood. In the current study, we demonstrate that metastasis-associated behaviors of ovarian cancer cells and MCAs are influenced by cellular cadherin composition. Our results show that mesenchymal N-cadherin expressing (Ncad+) cells and MCAs invade much more efficiently than E-cadherin expressing (Ecad+) cells. Ncad+ MCAs exhibit rapid lateral dispersal prior to penetration of three-dimensional collagen matrices. When seeded as individual cells, lateral migration and cell-cell junction formation precede matrix invasion. Neutralizing the Ncad extracellular domain with the monoclonal antibody GC-4 suppresses lateral dispersal and cell penetration of collagen gels. In contrast, use of a broad spectrum matrix metalloproteinase (MMP) inhibitor (GM6001) to block endogenous membrane type 1 matrix metalloproteinase (MT1-MMP) activity does not fully inhibit cell invasion. Using intact tissue explants, Ncad+ MCAs were also shown to efficiently rupture peritoneal mesothelial cells, exposing the sub-mesothelial collagen matrix. Acquisition of Ncad by E-cadherin expressing cells (Ecad+) increased mesothelial clearance activity, but was not sufficient to induce matrix invasion. Furthermore, co-culture of Ncad+ with Ecad+ cells did not promote a “leader-follower” mode of collective cell invasion, demonstrating that matrix remodeling and creation of invasive micro-tracks are not sufficient for cell penetration of collagen matrices in the absence of Ncad. Collectively, our data emphasize the role of Ncad in intraperitoneal seeding of EOC and provide the rationale for future studies targeting Ncad+ in pre-clinical models of EOC metastasis.

Celastrus orbiculatus extract inhibits the migration and invasion of human glioblastoma cells in vitro

BACKGROUND

Gliomas are highly aggressive tumors of the nervous system, and current treatments fail to improve patient survival. To identify substances that can be used as treatments for gliomas, we examined the effect of Celastrus orbiculatus extract (COE) on the invasion and migration of human glioblastoma U87 and U251 cells in vitro.

METHODS

The effects of COE on cell viability and adhesion were tested using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay and cell adhesion assay, respectively. The effects of COE on cell migration and invasion were assessed by a wound-healing assay and transwell migration and invasion assays. The effects of COE on the expression of epithelial-mesenchymal transition (EMT)-related proteins and matrix metalloproteinases (MMPs) were evaluated using western blot and gelatin zymography, respectively. Finally, the effect of COE on actin assembly was observed using phalloidin-tetramethylrhodamine isothiocyanate labeling and confocal laser scanning microscopy.

RESULTS

We found that COE inhibited the adhesion, migration, and invasion of U87 and U251 cells in a dose-dependent manner. COE reduced N-cadherin and vimentin expression, increased E-cadherin expression, and reduced MMP-2 and MMP-9 expression in U87 and U251 cells. Furthermore, COE inhibited actin assembly in U87 and U251 cells.

CONCLUSIONS

COE attenuates EMT, MMP expression, and actin assembly in human glioblastoma cells, thereby inhibiting their adhesion, migration, and invasion in vitro.

Selecting Targets for Tumor Imaging: An Overview of Cancer-Associated Membrane Proteins

Tumor targeting is a booming business: The global therapeutic monoclonal antibody market accounted for more than $78 billion in 2012 and is expanding exponentially. Tumors can be targeted with an extensive arsenal of monoclonal antibodies, ligand proteins, peptides, RNAs, and small molecules. In addition to therapeutic targeting, some of these compounds can also be applied for tumor visualization before or during surgery, after conjugation with radionuclides and/or near-infrared fluorescent dyes. The majority of these tumor-targeting compounds are directed against cell membrane-bound proteins. Various categories of targetable membrane-bound proteins, such as anchoring proteins, receptors, enzymes, and transporter proteins, exist. The functions and biological characteristics of these proteins determine their location and distribution on the cell membrane, making them more, or less, accessible, and therefore, it is important to understand these features. In this review, we evaluate the characteristics of cancer-associated membrane proteins and discuss their overall usability for cancer targeting, especially focusing on imaging applications.

Overexpression of p42.3 promotes cell proliferation, migration, and invasion in human gastric cancer cells

As a newly discovered tumor-specific gene, p42.3 is overexpressed in most of human gastric cancers (GC). However, the role of p42.3 in GC progression remains unclear. To assess the role of p42.3 in gastric cancers, immunohistochemistry and western blot were performed to detect the p42.3 expression in human GC tissues and cells. We also investigated the role of p42.3 in GC cell proliferation, migration, and invasion. Our results showed that the p42.3 expression was increased dramatically in human GC tissue and cells. In addition, we found that overexpression of p42.3 promotes GC cell proliferation, migration, and invasion abilities. Furthermore, p42.3 expression suppressed the E-cadherin protein level and promoted the β-catenin and p-ERK protein level. Taken together, overexpressed p42.3 is correlated with gastric cancer cell proliferation, migration, and invasion, suggesting its use as a biological marker in gastric cancer.

Epidermal Growth Factor Receptor Mutation Enhances Expression of Cadherin-5 in Lung Cancer Cells

Epidermal growth factor receptor (EGFR) activation has been shown to play a critical role in tumor angiogenesis. In this study, we investigate the correlation between EGFR mutations and cadherin-5 (CDH5), which is an angiogenic factor, in lung cancer cells. Increased expression CDH5 is observed in lung cancer cells with EGFR mutations. Stable lung cancer cell lines expressing mutant (exon 19 deletion E746-A750, and exon 21 missense mutation L858R) and wild type EGFR genes are established. A significantly higher expression of CDH5 is observed in exon 19 deletion stable lung cancer cells and mouse xenografts. Further studies show that expression of CDH5 is decreased after the inhibition of EGFR and downstream Akt pathways in lung cancer cells with EGFR mutation. In addition, mutant EGFR genes potentiates angiogenesis in lung cancer cells, which is inhibited by CDH5 siRNA, and potentiates migration and invasion in lung cancer cells. Our study shows that mutant EGFR genes are associated with overexpression of CDH5 through increased phosphorylation of EGFR and downstream Akt pathways. Our result may provide an insight into the association of mutant EGFR and CDH5 expression in lung cancer and aid further development of target therapy for NSCLC in the future.

Serum replacement with albumin-associated lipids prevents excess aggregation and enhances growth of induced pluripotent stem cells in suspension culture

Suspension culture systems are currently under investigation for the mass production of pluripotent stem (PS) cells for tissue engineering; however, the control of cell aggregation in suspension culture remains challenging. Existing methods to control aggregation such as microwell culture are difficult to scale up. To address this issue, in this study a novel method that incorporates the addition of KnockOut Serum Replacement (KSR) to the PS cell culture medium was described. The method regulated cellular aggregation and significantly improved cell growth (a 2- to 10-fold increase) without any influence on pluripotency. In addition, albumin-associated lipids as the major working ingredient of KSR responsible for this inhibition of aggregation were identified. This is one of the simplest methods described to date to control aggregation and requires only chemically synthesizable reagents. Thus, this method has the potential to simplify the mass production process of PS cells and thus lower their cost. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1009-1016, 2016.

Crystal Structure of Human E-Cadherin-EC1EC2 in Complex with a Peptidomimetic Competitive Inhibitor of Cadherin Homophilic Interaction

Cadherins are transmembrane cell adhesion proteins whose aberrant expression often correlates with cancer development and proliferation. We report the crystal structure of an E-cadherin extracellular fragment in complex with a peptidomimetic compound that was previously shown to partially inhibit cadherin homophilic adhesion. The structure reveals an unexpected binding mode and allows the identification of a druggable cadherin interface, thus paving the way to a future structure-guided design of cell adhesion inhibitors against cadherin-expressing solid tumors.

Synthesis, characterization and biological evaluation of a (67)Ga-labeled (η(6)-Tyr)Ru(η(5)-Cp) peptide complex with the HAV motif

Heterobimetallic complexes with the evolutionary, well-preserved, histidyl-alanyl-valinyl (HAV) sequence for cadherin targeting, an organometallic Ru core with anticancer activity and a radioactive moiety for imaging may hold potential as theranostic agents for cancer. Visible-light irradiation of the HAVAY-NH2 pentapeptide in the presence of [(η(5)-Cp)Ru(η(6)-naphthalene)](+) resulted in the formation of a full sandwich type complex, (η(6)-Tyr-RuCp)-HAVAY-NH2 in aqueous solution, where the metal ion is connected to the Tyr (Y) unit of the peptide. Conjugation of this complex to 2,2'-(7-(1-carboxy-4-((4-isothiocyanatobenzyl)amino)-4-oxobutyl)-1,4,7-triazonane-1,4-diyl)diacetic acid (NODA-GA) and subsequent metalation of the resulting product with stable ((nat)Ga) and radioactive ((67)Ga) isotope yielded (nat)Ga/(67)Ga-NODA-GA-[(η(6)-Tyr-RuCp)-HAVAY-NH2]. The non-radioactive compounds were characterized by NMR spectroscopy and Mass Spectrometry. The cellular uptake and cytotoxicity of the radioactive and non-radioactive complexes, respectively, were evaluated in various human cancer cell lines characterized by different levels of N- or E-cadherins expression. Results from these studies indicate moderate cellular uptake of the radioactive complexes. However, the inhibition of the cell proliferation was not relevant.

Cell adhesion and urothelial bladder cancer: the role of cadherin switching and related phenomena

Cadherins are mediators of cell-cell adhesion in epithelial tissues. E-cadherin is a known tumour suppressor and plays a central role in suppressing the invasive phenotype of cancer cells. However, the abnormal expression of N- and P-cadherin ('cadherin switching', CS) has been shown to promote a more invasive and m̀alignant phenotype of cancer, with P-cadherin possibly acting as a key mediator of invasion and metastasis in bladder cancer. Cadherins are also implicated in numerous signalling events related to embryonic development, tissue morphogenesis and homeostasis. It is these wide ranging effects and the serious implications of CS that make the cadherin cell adhesion molecules and their related pathways strong candidate targets for the inhibition of cancer progression, including bladder cancer. This review focuses on CS in the context of bladder cancer and in particular the switch to P-cadherin expression, and discusses other related molecules and phenomena, including EpCAM and the development of the cancer stem cell phenotype.

N-cadherin antagonists as oncology therapeutics

The cell adhesion molecule (CAM), N-cadherin, has emerged as an important oncology therapeutic target. N-cadherin is a transmembrane glycoprotein mediating the formation and structural integrity of blood vessels. Its expression has also been documented in numerous types of poorly differentiated tumours. This CAM is involved in regulating the proliferation, survival, invasiveness and metastasis of cancer cells. Disruption of N-cadherin homophilic intercellular interactions using peptide or small molecule antagonists is a promising novel strategy for anti-cancer therapies. This review discusses: the discovery of N-cadherin, the mechanism by which N-cadherin promotes cell adhesion, the role of N-cadherin in blood vessel formation and maintenance, participation of N-cadherin in cancer progression, the different types of N-cadherin antagonists and the use of N-cadherin antagonists as anti-cancer drugs.

Synergistic Antiproliferative Effects of a New Cucurbitacin B Derivative and Chemotherapy Drugs on Lung Cancer Cell Line A549

Nonsmall cell lung cancer (NSCLC) represents an important cause of mortality worldwide due to its aggressiveness and growing resistance to currently available therapy. Cucurbitacins have emerged as novel potential anticancer agents showing strong antiproliferative effects and can be promising candidates for combined treatments with clinically used anticancer agents. This study investigates the synergistic antiproliferative effects of a new semisynthetic derivative of cucurbitacin B (DACE) with three chemotherapy drugs: cisplatin (CIS), irinotecan (IRI), and paclitaxel (PAC) on A549 cells. The most effective combinations were selected for studies of the mechanism of action. Using an in silico tool, DACE seems to act by a different mechanism of action when compared with that of different classes of drugs already used in clinical settings. DACE also showed potent synergic effects with drugs, and the most potent combinations induced G2/M cell cycle arrest by modulating survivin and p53 expression, disruption of F-actin cytoskeleton, and cell death by apoptosis. These treatments completely inhibited the clonogenic potential and did not reduce the proliferation of nontumoral lung cells (MRC-5). DACE also showed relevant antimigratory and anti-invasive effects, and combined treatments modulated cell migration signaling pathways evolved with metastasis progression. The effects of DACE associated with drugs was potentiated by the oxidant agent l-buthionine-sulfoximine (BSO), and attenuated by N-acetilcysteine (NAC), an antioxidant agent. The antiproliferative effects induced by combined treatments were attenuated by a pan-caspase inhibitor, indicating that the effects of these treatments are dependent on caspase activity. Our data highlight the therapeutic potential of DACE used in combination with known chemotherapy drugs and offer important insights for the development of more effective and selective therapies against lung cancer.

Computational design of novel peptidomimetic inhibitors of cadherin homophilic interactions

We report a first set of peptidomimetic ligands mimicking the adhesive interface identified by recent crystallographic structures of E- and N-cadherin. Compounds 2 and 3 inhibit adhesion of epithelial ovarian cancer (EOC) cells with improved efficacy compared to the ADH-1 peptide, a N-cadherin antagonist that is in early clinical trials in EOC patients.

Ex Vivo Maintenance of Primary Human Multiple Myeloma Cells through the Optimization of the Osteoblastic Niche

We previously reported a new approach for culturing difficult-to-preserve primary patient-derived multiple myeloma cells (MMC) using an osteoblast (OSB)-derived 3D tissue scaffold constructed in a perfused microfluidic environment and a culture medium supplemented with patient plasma. In the current study, we used this biomimetic model to show, for the first time, that the long-term survival of OSB is the most critical factor in maintaining the ex vivo viability and proliferative capacity of MMC. We found that the adhesion and retention of MMC to the tissue scaffold was meditated by osteoblastic N-cadherin, as one of potential mechanisms that regulate MMC-OSB interactions. However, in the presence of MMC and patient plasma, the viability and osteogenic activity of OSB became gradually compromised, and consequently MMC could not remain viable over 3 weeks. We demonstrated that the long-term survival of both OSB and MMC could be enhanced by: (1) optimizing perfusion flow rate and patient-derived plasma composition in the culture medium and (2) replenishing OSB during culture as a practical means of prolonging MMC's viability beyond several weeks. These findings were obtained using a high-throughput well plate-based perfusion device from the perspective of optimizing the ex vivo preservation of patient-derived MM biospecimens for downstream use in biological studies and chemosensitivity analyses.

New Insights into the Molecular Mechanism of E-Cadherin-Mediated Cell Adhesion by Free Energy Calculations

Three-dimensional domain swapping is an important mode of protein association leading to the formation of stable dimers. Monomers associating via this mechanism mutually exchange a domain to form a homodimer. Classical cadherins, an increasingly important target for anticancer therapy, use domain swapping to mediate cell adhesion. However, despite its importance, the molecular mechanism of domain swapping is still debated. Here, we study the conformational changes that lead to activation and dimerization via domain swapping of E-cadherin. Using state-of-the-art enhanced sampling atomistic simulations, we reconstruct its conformational free energy landscape, obtaining the free energy profile connecting the inactive and active form. Our simulations predict that the E-cadherin monomer populates the open and closed forms almost equally, which is in agreement with the proposed "selected fit" mechanism in which monomers in an active conformational state bind to form a homodimer, analogous to the conformational selection mechanism often observed in ligand-target binding. Moreover, we find that the open state population is increased in the presence of calcium ions at the extracellular boundary, suggesting their possible role as allosteric activators of the conformational change.

Matrine inhibits the invasive properties of human glioma cells by regulating epithelial‑to‑mesenchymal transition

Matrine is reported to be effective in tumor therapies; however, the anti‑metastatic effect and molecular mechanism(s) of matrine on glioma remain poorly understood. Therefore, the purpose of this study was to assess the effects of matrine on glioma and the associated mechanism(s). In the study, we demonstrated that matrine inhibited the proliferation of glioma cells. We also observed that matrine inhibited the migration and invasion of glioma cells at non‑toxic concentrations. Matrine also decreased the expression of E‑cadherin and increased the expression of N‑cadherin. These results suggest that the anti‑metastatic effect of matrine may be correlated with epithelial‑to‑mesenchymal transition (EMT). Moreover, matrine could reduce the phosphorylation levels of p38 and AKT proteins. In conclusion, these results suggest matrine may be a potential alternative against invasive glioma cells via the p38 MAPK and AKT signaling‑dependent inhibition of EMT.

Disorganized vascular structures in sporadic venous malformations: a possible correlation with balancing effect between Tie2 and TGF-β

Venous malformations (VMs) are among the most common slow-flow vascular malformations characterized by irregular venous channels, luminal thrombi, and phleboliths. To systematically manifest the disorganized vascular structures in sporadic VMs, we initially evaluated histopathological characteristics, perivascular cell coverage, adhesion molecules expression and vascular ultrastructures. Then, the expression of Tie2 and TGF-β in VMs was detected. Meanwhile, the in vitro studies were performed for mechanism investigation. Our data showed that the perivascular α-SMA⁺ cell coverage and expression of adhesion molecules in VMs were significantly decreased compared with those in the normal skin tissues. We also found that the expression and phosphorylation levels of Tie2 were upregulated, whereas TGF-β was downregulated in VMs, and they were negatively correlated. Moreover, the in vitro results also revealed a possible balancing effect between Tie2 and TGF-β, as demonstrated by the findings that Ang-1 (agonist of Tie2) treatment significantly downregulated TGF-β expression, and treatment with recombinant TGF-β could also suppress Tie2 expression and phosphorylation. This study provided strong evidence supporting the disorganized vascular structures and dysregulation of related molecules in sporadic VMs, and demonstrated a possible balancing effect between Tie2 and TGF-β, which might help to develop novel therapeutics for vascular disorganization-related disorders.

RY10-4 suppressed metastasis of MDA-MB-231 by stabilizing ECM and E-cadherin

In the article, we investigated the anti-metastasis mechanism of RY10-4, an anti-tumor compound derived from protoapigenone, in breast tumor cells MB-MDA-231. The analog of protoapigenone with an unaromatic B-ring was verified to suppress the proliferation of several tumor cells by previous research that also showed that several tumor progression such as inducing apoptosis and anti-angiogenesis could be acted on by RY10-4. In the article, we investigated the mechanism about how RY10-4 suppressed the invasion of MDA-MB-231. Firstly, the transwells assays with and without matrigel were adapted to evaluate the anti-metastasis and anti-invasion activity. Much research had demonstrated that the ECM and E-cadherin/β-catenin complex play an important role in cell adhesion and the formation of the cell skeleton, and as we knew the abnormal and absent expression of ECM and E-cadherin/β-catenin complex are found in many malignant cells. The result demonstrated that the amount and distribution of E-cadherin/β-catenin complex were backed on track by RY10-4, and the expression of MMP-2/9 in MDA-MB-231, which functions as a major negative factor of ECM, was down-regulated after co-cultured with RY10-4. Furthermore the pathway related to MMP-2/9 and E-cadherin was assessed by the western blot. As the results showed, the MAPK pathway and the spread of β-catenin were affected by RY10-4 to exert the anti-metastasis on MDA-MB-231. Collectively, the research revealed a novel anti-tumor ability of RY10-4 by inhibiting migration and invasion in MDA-MB-231.

Identification and characterization of the X-dimer of human P-cadherin: implications for homophilic cell adhesion

Cell adhesion mediated by cadherins depends critically on the homophilic trans-dimerization of cadherin monomers from apposing cells, generating the so-called strand-swap dimer (ss-dimer). Recent evidence indicates that the ss-dimer is preceded by an intermediate species known as the X-dimer. Until now, the stabilized form of the X-dimer had only been observed in E-cadherin among the classical type I cadherins. Herein, we report the isolation and characterization of the analogous X-dimer of human P-cadherin. Small-angle X-ray scattering (SAXS) and site-directed mutagenesis data indicates that the overall architecture of the X-dimer of human P-cadherin is similar to that of E-cadherin. The X-dimerization is triggered by Ca(2+) and governed by specific protein-protein interactions. The attachment of three molecules of Ca(2+) with high affinity (Kd = 9 μM) stabilizes the monomeric conformation of P-cadherin (ΔTm = 17 °C). The Ca(2+)-stabilized monomer subsequently dimerizes in the X-configuration by establishing protein-protein interactions that require the first two extracellular domains of the cadherin. The homophilic X-dimerization is very specific, as the presence of the highly homologous E-cadherin does not interfere with the self-recognition of P-cadherin. These data suggest that the X-dimer could play a key role in the specific cell-cell adhesion mediated by human P-cadherin.

N-cadherin and P-cadherin are biomarkers for invasion, metastasis, and poor prognosis of gallbladder carcinomas

Gallbladder cancer (GBC) is a rare, but highly aggressive cancer. The most common type of gallbladder cancer is adenocarcinoma (AC), while squamous cell/adenosquamous carcinoma (SC/ASC) is a rare type of gallbladder cancer. The clinicopathologic and biological characteristics of SC/ASC have not been well documented. In this study, the protein expression of N-cadherin and P-cadherin in 46 SC/ASCs and 80 ACs was measured using immunohistochemistry. We demonstrated that positive N-cadherin and P-cadherin expression were significantly associated with large tumor size, invasion, and lymph node metastasis of both SC/ASC and AC. In contrast, positive N-cadherin and P-cadherin expression were significantly associated with differentiation and TNM stage in only AC. Univariate Kaplan-Meier analysis showed that positive N-cadherin and P-cadherin expression, differentiation, tumor size, TNM stage, invasion, lymph node metastasis, and surgical curability were significantly associated with overall survival in both SC/ASC and AC patients. Multivariate Cox regression analysis showed that positive N-cadherin and P-cadherin expression are independent poor-prognostic factors in both SC/ASC and AC patients. Our study suggested that positive N-cadherin and P-cadherin expression closely correlated with clinicopathological and biological behaviors, and poor-prognosis of gallbladder cancer.

Cell adhesion molecules in metastatic neuroblastoma models

Several cell adhesion molecules (CAMs) including selectins, integrins, cadherins and immunoglobulin-like CAMs are involved in leukocyte adhesion especially at sites of inflammation. In cancer cells, these CAMs have been associated with the growth and metastatic behavior in several malignant entities. In this study adhesion of LAN 1 and SK-N-SH neuroblastoma cells to selectins, hyaluronan and endothelial cells were determined under flow conditions. Furthermore cells were injected subcutaneously into wildtype and selectin deficient scid mice and their growth and metastatic behavior were analyzed. Under shear stress SK-N-SH cells firmly adhered to E-selectin-Fc-fusion protein, hyaluronan and endothelial cells, while LAN 1 cells showed less or hardly any adhesive events by comparison. In the SK-N-SH xenograft model metastasis formation was slightly dependent on the expression of selectins, while LAN 1 cells developed metastases completely independent of selectin expression. The different adhesive and metastatic properties of LAN 1 and SK-N-SH cells are reflected by a different expression profile of several CAMs. The results indicate that endothelial selectins are not essential for metastasis formation of human LAN 1 and SK-N-SH cells. However, other CAMs namely CD44, N-cadherin, NCAM and integrins were upregulated or downregulated, respectively, in SK-N-SH and LAN 1 cells and are potential adhesion molecules involved in the metastatic cascade of these cells.

Cell adhesion molecules and their relation to (cancer) cell stemness

Despite decades of search for anticancer drugs targeting solid tumors, this group of diseases remains largely incurable, especially if in advanced, metastatic stage. In this review, we draw comparison between reprogramming and carcinogenesis, as well as between stem cells (SCs) and cancer stem cells (CSCs), focusing on changing garniture of adhesion molecules. Furthermore, we elaborate on the role of adhesion molecules in the regulation of (cancer) SCs division (symmetric or asymmetric), and in evolving interactions between CSCs and extracellular matrix. Among other aspects, we analyze the role and changes of expression of key adhesion molecules as cancer progresses and metastases develop. Here, the role of cadherins, integrins, as well as selected transcription factors like Twist and Snail is highlighted, not only in the regulation of epithelial-to-mesenchymal transition but also in the avoidance of anoikis. Finally, we briefly discuss recent developments and new strategies targeting CSCs, which focus on adhesion molecules or targeting tumor vasculature.

Decreased interleukin-20 level in patients with systemic sclerosis: are they related with angiogenesis?

In this study, we aimed to evaluate the relation between angiogenesis indicators and T helper 17 cytokine group in patients with systemic sclerosis (SSc) which is a disease characterized by impaired angiogenesis and autoimmune response. In our study, patients with SSc are compared with patients with primary Raynaud's phenomenon (RP) and healthy controls. Forty SSc patients, 18 primary RP cases, and 20 healthy controls were included in our study. The demographic and clinical features of patients with SSc were recorded. The serum levels of vascular endothelial growth factor (VEGF), vascular endothelial (VE)-cadherin, interleukin (IL)-20, IL-22, and IL-23 were assessed. In the SSc group, IL-20 level was significantly lower than in both primary RP group and controls (p values <0.001). VE-cadherin level in SSc was significantly higher than in primary RP (p = 0.016). The IL-22 and IL-23 and VEGF levels of SSc, primary RP, and control groups were similar (p values >0.05). In SSc patients, IL-23 correlated negatively with VEGF (r = -0.36, p = 0.025) and positively with VE-cadherin (r = 0.55, p < 0.001). IL-20 levels in SSc patients correlated with disease duration (r = 0.32, p = 0.044). SSc patients with limited involvement had significantly higher VE-cadherin levels than SSc patients with diffuse involvement (p = 0.044). We observed that IL-20 which is an IL-10 group angiogenesis indicator was observed to be suppressed in SSc, suggesting abnormal angiogenesis.

Upregulated expression levels of ADAM10 and EGFR and downregulated expression levels of E-cadherin in hepatocellular carcinomas

The aim of this study was to investigate the expression and significance of a disintegrin and metalloproteinase 10 (ADAM10), epidermal growth factor receptor (EGFR) and E-cadherin protein in hepatocellular carcinomas. The expression levels of ADAM10, EGFR and E-cadherin were analyzed in 40 cases of hepatocellular carcinoma using immunohistochemistry and quantitative polymerase chain reaction (qPCR). The expression levels of ADAM10, EGFR and E-cadherin were significantly correlated with portal vein thrombosis, intrahepatic metastasis, differentiation degree and tumor size (P<0.05). In hepatocellular carcinoma, the expression levels of ADAM10 and EGFR were increased and the levels of E-cadherin were decreased compared with those in the adjacent tissues. The elevated expression levels of ADAM10 and EGFR may be associated with the malignancy of the tumors. E-cadherin expression is negatively correlated with the degree of malignancy. The detection of ADAM10, EGFR and E-cadherin expression levels may contribute to an understanding of the oncogenesis and development of hepatocellular carcinomas.

Anti-cadherin-17 antibody modulates beta-catenin signaling and tumorigenicity of hepatocellular carcinoma

Cadherin-17 (CDH17) is an oncofetal molecule associated with poor prognostic outcomes of hepatocellular carcinoma (HCC), for which the treatment options are very limited. The present study investigates the therapeutic potential of a monoclonal antibody (Lic5) that targets the CDH17 antigen in HCC. In vitro experiments showed Lic5 could markedly reduce CDH17 expression in a dose-dependent manner, suppress β-catenin signaling, and induce cleavages of apoptotic enzymes caspase-8 and -9 in HCC cells. Treatment of animals in subcutaneous HCC xenograft model similarly demonstrated significant tumor growth inhibition (TGI) using Lic5 antibody alone (5 mg/kg, i.p., t.i.w.; ca.60–65% TGI vs. vehicle at day 28), or in combination with conventional chemotherapy regimen (cisplatin 1 mg/kg; ca. 85–90% TGI). Strikingly, lung metastasis was markedly suppressed by Lic5 treatments. Immunohistochemical and western blot analyses of xenograft explants revealed inactivation of the Wnt pathway and suppression of Wnt signaling components in HCC tissues. Collectively, anti-CDH17 antibody promises as an effective biologic agent for treating malignant HCC.

Significance of preoperative tissue levels of vascular-endothelial cadherin, liver-intestine cadherin and vascular endothelial growth factor in gastric cancer

BACKGROUND/AIMS

The aims of this study were to examine the expressions of endothelium specific VE-cadherin, intestine specific LI-cadherin, and vascular endothelial growth factor (VEGF), and to determine their relationships with the clinicopathological parameters of gastric cancer.

METHODS

A total 47 patients with gastric cancer who underwent surgery were enrolled. Endoscopic biopsies were obtained from the cancer and normal mucosa, respectively. Using semiquantitative RT-PCR, the mRNA expression levels of VE-cadherin, LI-cadherin and VEGF were measured by tumor/normal (T/N) ratios. The protein expressions of VE-cadherin, LI-cadherin and VEGF were examined by Western blot and immunohistochemical stain in surgically resected tissues. The clinicopathological variables were reviewed and analyzed, retrospectively.

RESULTS

Twenty two cases (46.8%) of VE-cadherin, 25 cases (53.2%) of LI-cadherin and 27 cases (51.1%) of VEGF mRNA expressions were overexpressed in gastric cancer compared to normal tissue. There was a tendency for T/N ratio of VE-cadherin mRNA to correlate with the lymphatic invasion (p=0.07) and the lymph node metastasis (p=0.099) in advanced gastric cancer. The T/N ratio of LI-cadherin mRNA showed significant association with distant metastasis (p=0.031) and lymphatic invasion especially in advanced gastric cancer (p=0.023). There was a tendency for the T/N ratio of VEGF mRNA to correlate with the distant metastasis (p=0.073) in advanced gastric cancer.

CONCLUSIONS

As increased mRNA expression of LI-cadherin was associated with distant metastasis and lymphatic invasion especially in the biopsy specimen of advanced gastric cancer before surgery, it may provide useful preoperative information on tumor aggressiveness.

Hitting Them Where They Live: Targeting the Glioblastoma Perivascular Stem Cell Niche

Glioblastoma growth potential and resistance to therapy is currently largely attributed to a subset of tumor cells with stem-like properties. If correct, this means that cure will not be possible without eradication of the stem cell fraction and abrogation of those mechanisms through which stem cell activity is induced and maintained. Glioblastoma stem cell functions appear to be non-cell autonomous and the consequence of tumor cell residence within specialized domains such as the perivascular stem cell niche. In this review we consider the multiple cellular constituents of the perivascular niche, the molecular mechanisms that support niche structure and function and the implications of the perivascular localization of stem cells for anti-angiogenic approaches to cure.

Anti-metastatic and anti-angiogenic activities of sulfated polysaccharide of Sepiella maindroni ink

A previous study demonstrated that SIP-SII, a sulfated Sepiella maindroni ink polysaccharide, suppressed the invasion and migration of cancer cells via the inhibition of the proteolytic activity of matrix metalloproteinase-2 (MMP-2). Therefore, this study investigated the anti-metastatic effect of SIP-SII in vivo. SIP-SII (15 and 30 mg/kg d) markedly decreased B16F10 pulmonary metastasis in mice models by 85.9% and 88.0%, respectively. Immunohistochemistry showed that SIP-SII decreased the expression of the intercellular adhesion molecule 1 (ICAM-1) and basic fibroblast growth factor (bFGF) in lung metastasis nodules. In addition, SIP-SII inhibited neovascularization in chick chorioallantoic membrane assay at 0.08-2 mg/mL. In the in vitro experiments, SIP-SII (0.8-500 μg/mL) significantly decreased the protein and mRNA expression of ICAM-1 and bFGF in SKOV3 and EA.hy926 cells, respectively. These results suggested that SIP-SII might suppress melanoma metastasis via the inhibition of the tumor adhesion mediated by ICAM-1 and the angiogenesis mediated by bFGF, as well as resulting in depression of the invasion and migration of carcinoma cells.

Prostaglandins in cancer cell adhesion, migration, and invasion

Prostaglandins exert a profound influence over the adhesive, migratory, and invasive behavior of cells during the development and progression of cancer. Cyclooxygenase-2 (COX-2) and microsomal prostaglandin E₂ synthase-1 (mPGES-1) are upregulated in inflammation and cancer. This results in the production of prostaglandin E₂ (PGE₂), which binds to and activates G-protein-coupled prostaglandin E_1–4 receptors (EP_1–4). Selectively targeting the COX-2/mPGES-1/PGE₂/EP_1–4 axis of the prostaglandin pathway can reduce the adhesion, migration, invasion, and angiogenesis. Once stimulated by prostaglandins, cadherin adhesive connections between epithelial or endothelial cells are lost. This enables cells to invade through the underlying basement membrane and extracellular matrix (ECM). Interactions with the ECM are mediated by cell surface integrins by “outside-in signaling” through Src and focal adhesion kinase (FAK) and/or “inside-out signaling” through talins and kindlins. Combining the use of COX-2/mPGES-1/PGE₂/EP_1–4 axis-targeted molecules with those targeting cell surface adhesion receptors or their downstream signaling molecules may enhance cancer therapy.

N-cadherin in neuroblastoma disease: expression and clinical significance

One of the first and most important steps in the metastatic cascade is the loss of cell-cell and cell-matrix interactions. N-cadherin, a crucial mediator of homotypic and heterotypic cell-cell interactions, might play a central role in the metastasis of neuroblastoma (NB), a solid tumor of neuroectodermal origin. Using Reverse Transcription Quantitative PCR (RT-qPCR), Western blot, immunocytochemistry and Tissue MicroArrays (TMA) we demonstrate the expression of N-cadherin in neuroblastoma tumors and cell lines. All neuroblastic tumors (n = 356) and cell lines (n = 10) expressed various levels of the adhesion protein. The N-cadherin mRNA expression was significantly lower in tumor samples from patients suffering metastatic disease. Treatment of NB cell lines with the N-cadherin blocking peptide ADH-1 (Exherin, Adherex Technologies Inc.), strongly inhibited tumor cell proliferation in vitro by inducing apoptosis. Our results suggest that N-cadherin signaling may play a role in neuroblastoma disease, marking involvement of metastasis and determining neuroblastoma cell viability.

Roles of STAT3 and ZEB1 proteins in E-cadherin down-regulation and human colorectal cancer epithelial-mesenchymal transition

The progression of colorectal carcinoma (CRC) to invasive and metastatic disease may involve localized occurrences of epithelial-mesenchymal transition (EMT). However, mechanisms of the EMT process in CRC progression are not fully understood. We previously showed that knockdown of signal transducer and activator of transcription 3 (STAT3) up-regulated E-cadherin (a key component in EMT progression) in CRC. In this study, we examined the roles of STAT3 in CRC EMT and ZEB1, an EMT inducer, in STAT3-induced down-regulation of E-cadherin. Knockdown of STAT3 significantly increased E-cadherin and decreased N-cadherin and vimentin expressions in highly invasive LoVo CRC cells. Meanwhile, overexpression of STAT3 significantly reduced E-cadherin and enhanced N-cadherin and vimentin expressions in weakly invasive SW1116 CRC cells. Activation of STAT3 significantly increased CRC cell invasiveness and resistance to apoptosis. Knockdown of STAT3 dramatically enhanced chemosensitivity of CRC cells to fluorouracil. STAT3 regulated ZEB1 expression in CRC cells, and the STAT3-induced decrease in E-cadherin and cell invasion depended on activation of ZEB1 in CRC cells. Additionally, pSTAT3(Tyr-705) and ZEB1 expressions were significantly correlated with TNM (tumor, lymph node, and metastasis stages) (p < 0.01). In conclusion, STAT3 may directly mediate EMT progression and regulate ZEB1 expression in CRC. ZEB1 may participate in STAT3-induced cell invasion and E-cadherin down-regulation in CRC cells. The expressions of pSTAT3(Tyr-705) and ZEB1 may be positively associated with CRC metastasis. Our data may provide potential targets to prevent and/or treat CRC invasion and metastasis.

E-N-cadherin heterodimers define novel adherens junctions connecting endoderm-derived cells

Intercellular junctions play a pivotal role in tissue development and function and also in tumorigenesis. In epithelial cells, decrease or loss of E-cadherin, the hallmark molecule of adherens junctions (AJs), and increase of N-cadherin are widely thought to promote carcinoma progression and metastasis. In this paper, we show that this "cadherin switch" hypothesis does not hold for diverse endoderm-derived cells and cells of tumors derived from them. We show that the cadherins in a major portion of AJs in these cells can be chemically cross-linked in E-N heterodimers. We also show that cells possessing E-N heterodimer AJs can form semistable hemihomotypic AJs with purely N-cadherin-based AJs of mesenchymally derived cells, including stroma cells. We conclude that these heterodimers are the major AJ constituents of several endoderm-derived tissues and tumors and that the prevailing concept of antagonistic roles of these two cadherins in developmental and tumor biology has to be reconsidered.

The cancer stem cell niche--there goes the neighborhood?

The niche is the environment in which stem cells reside and is responsible for the maintenance of unique stem cell properties such as self-renewal and an undifferentiated state. The heterogeneous populations which constitute a niche include both stem cells and surrounding differentiated cells. This network of heterogeneity is responsible for the control of the necessary pathways that function in determining stem cell fate. The concept that cancer stem cells, a subpopulation of cells responsible for tumor initiation and formation, reside in their own unique niche is quickly evolving and it is of importance to understand and identify the processes occurring within this environment. The necessary intrinsic pathways that are utilized by this cancer stem cell population to maintain both self-renewal and the ability to differentiate are believed to be a result of the environment where cancer stem cells reside. The ability of a specific cancer stem cell niche to provide the environment in which this population can flourish is a critical aspect of cancer biology that mandates intense investigation. This review focuses on current evidence demonstrating that homeostatic processes such as inflammation, epithelial to mesenchymal transition, hypoxia and angiogenesis contribute to the maintenance and control of cancer stem cell fate by providing the appropriate signals within the microenvironment. It is necessary to understand the key processes occurring within this highly specialized cancer stem cell niche to identify potential therapeutic targets that can serve as the basis for development of more effective anticancer treatments.