VE-cadherin RGD motifs promote metastasis and constitute a potential therapeutic target in melanoma and breast cancers

VE-cadherin junction dynamics in initial lymphatic vessels promotes lymph node metastasis

The endothelial junction component vascular endothelial (VE)-cadherin governs junctional dynamics in the blood and lymphatic vasculature. Here, we explored how lymphatic junction stability is modulated by elevated VEGFA signaling to facilitate metastasis to sentinel lymph nodes. Zippering of VE-cadherin junctions was established in dermal initial lymphatic vessels after VEGFA injection and in tumor-proximal lymphatics in mice. Shape analysis of pan-cellular VE-cadherin fragments revealed that junctional zippering was accompanied by accumulation of small round-shaped VE-cadherin fragments in the lymphatic endothelium. In mice expressing a mutant VEGFR2 lacking the Y949 phosphosite (Vegfr2 Y949F/Y949F ) required for activation of Src family kinases, zippering of lymphatic junctions persisted, whereas accumulation of small VE-cadherin fragments was suppressed. Moreover, tumor cell entry into initial lymphatic vessels and subsequent metastatic spread to lymph nodes was reduced in mutant mice compared with WT, after challenge with B16F10 melanoma or EO771 breast cancer. We conclude that VEGFA mediates zippering of VE-cadherin junctions in initial lymphatics. Zippering is accompanied by increased VE-cadherin fragmentation through VEGFA-induced Src kinase activation, correlating with tumor dissemination to sentinel lymph nodes.

Proteomic profiling and network biology of colorectal cancer liver metastasis

INTRODUCTION

Tissue-based proteomic studies of colorectal cancer (CRC) metastasis have delivered fragmented results, with very few therapeutic targets and prognostic biomarkers moving beyond the discovery phase. This situation is likely due to the difficulties in obtaining and analyzing large numbers of patient-derived metastatic samples, the own heterogeneity of CRC, and technical limitations in proteomics discovery. As an alternative, metastatic CRC cell lines provide a flexible framework to investigate the underlying mechanisms and network biology of metastasis for target discovery.

AREAS COVERED

In this perspective, we comment on different in-depth proteomic studies of metastatic versus non-metastatic CRC cell lines. Identified metastasis-related proteins are introduced and discussed according to the spatial location in different cellular fractions, with special emphasis on membrane/adhesion proteins, secreted proteins, and nuclear factors, including miRNAs associated with liver metastasis. Moreover, we analyze the biological significance and potential therapeutic applications of the identified liver metastasis-related proteins.

EXPERT OPINION

The combination of protein discovery and functional analysis is the only way to accelerate the progress to clinical translation of the proteomic-derived findings in a relatively fast pace. Patient-derived organoids represent a promising alternative to patient tissues and cell lines, but further optimizations are still required for achieving solid and reproducible results.

Comprehensive analysis of prognostic significance of cadherin (CDH) gene family in breast cancer

Breast cancer is one of the leading deaths in all kinds of malignancies; therefore, it is important for early detection. At the primary tumor site, tumor cells could take on mesenchymal properties, termed the epithelial-to-mesenchymal transition (EMT). This process is partly regulated by members of the cadherin (CDH) family of genes, and it is an essential step in the formation of metastases. There has been a lot of study of the roles of some of the CDH family genes in cancer; however, a holistic approach examining the roles of distinct CDH family genes in the development of breast cancer remains largely unexplored. In the present study, we used a bioinformatics approach to examine expression profiles of CDH family genes using the Oncomine, Gene Expression Profiling Interactive Analysis 2 (GEPIA2), cBioPortal, MetaCore, and Tumor IMmune Estimation Resource (TIMER) platforms. We revealed that CDH1/2/4/11/12/13 messenger (m)RNA levels are overexpressed in breast cancer cells compared to normal cells and were correlated with poor prognoses in breast cancer patients’ distant metastasis-free survival. An enrichment analysis showed that high expressions of CDH1/2/4/11/12/13 were significantly correlated with cell adhesion, the extracellular matrix remodeling process, the EMT, WNT/beta-catenin, and interleukin-mediated immune responses. Collectively, CDH1/2/4/11/12/13 are thought to be potential biomarkers for breast cancer progression and metastasis.

Melanoma Tumour Vascularization and Tissue-Resident Endothelial Progenitor Cells

The aggressiveness of solid cancers, such as melanoma, relies on their metastatic potential. It has become evident that this key cause of mortality is largely conferred by the tumour-associated stromal cells, especially endothelial cells. In addition to their essential role in the formation of the tumour vasculature, endothelial cells significantly contribute to the establishment of the tumour microenvironment, thus enabling the dissemination of cancer cells. Melanoma tumour vascularization occurs through diverse biological processes. Vasculogenesis is the formation of de novo blood vessels from endothelial progenitor cells (EPCs), and recent research has shown the role of EPCs in melanoma tumour vascularization. A more detailed understanding of the complex role of EPCs and how they contribute to the abnormal vessel structures in tumours is of importance. Moreover, anti-angiogenic drugs have a limited effect on melanoma tumour vascularization, and the role of these drugs on EPCs remains to be clarified. Overall, targeting cancer vasculature remains a challenge, and the role of anti-angiogenic drugs and combination therapies in melanoma, a focus of this review, is an area of extensive exploration.

Gene Expression Patterns of Osteopontin Isoforms and Integrins in Malignant Melanoma

Osteopontin (OPN) is a multifunctional glycoprotein that physiologically interacts with different types of integrins. It is considered to be a possible prognostic biomarker in certain tumor types; however, various splicing isoforms exist, which have not been investigated in melanoma. We aimed to define the relative expression pattern of five OPN isoforms and clarify the prognostic significance of the splice variants in melanoma. We also aimed to investigate the expression pattern of eight integrins in the same tumors. Gene expression analyses revealed that the relative expression of OPNa, OPNb, and OPNc is significantly higher in metastatic tumors compared to primary lesions (p < 0.01), whereas the expression of OPN4 and OPN5 was low in both. The more aggressive nodular melanomas had higher expression levels compared to the superficial spreading subtype (p ≤ 0.05). The relative expression of the eight tested integrins was low, with only the expression of ITGB3 being detectable in nodular melanoma (Median_log2 = 1.274). A positive correlation was found between Breslow thickness and the expression of OPNc variant, whereby thicker tumors (>4 mm) had significantly higher expression (p ≤ 0.05). The Breslow thickness was negatively correlated with the expression of OPN4, and similarly with ITGA2. OPNc also exhibited significant positive correlation with the presence of metastasis. Our data show that high expression of OPNa, OPNb, and especially OPNc and low expression of OPN4 and ITGA2 are associated with an advanced stage of tumor progression and poor prognosis in melanoma.

The emerging roles of circular RNAs in vessel co-option and vasculogenic mimicry: clinical insights for anti-angiogenic therapy in cancers

Unexpected resistance to anti-angiogenic treatment prompted the investigation of non-angiogenic tumor processes. Vessel co-option (VC) and vasculogenic mimicry (VM) are recognized as primary non-angiogenic mechanisms. In VC, cancer cells utilize pre-existing blood vessels for support, whereas in VM, cancer cells channel and provide blood flow to rapidly growing tumors. Both processes have been implicated in the development of tumor and resistance to anti-angiogenic drugs in many tumor types. The morphology, but rare molecular alterations have been investigated in VC and VM. There is a pressing need to better understand the underlying cellular and molecular mechanisms. Here, we review the emerging circular RNA (circRNA)-mediated regulation of non-angiogenic processes, VC and VM.

Exosomes and organ-specific metastasis

The transmission of information between tumor cells and other cell types in the tumor microenvironment plays an important role in tumor metastasis and is critically modulated by exosomes and other mediators. Tumor-derived exosomes can promote epithelial-mesenchymal transition, angiogenesis, immune escape, formation of the pre-metastatic microenvironment, and transmission of drug-resistant molecules, thereby promoting tumor growth, invasion, and metastasis. Integrins are important regulatory molecules on exosomes that can locate metastatic cells at the initial stage of metastasis and show good organotropism. This fact suggests that a clear understanding of the roles of exosomal integrins will be beneficial for future clinical applications. Follow-up studies on exosomes using continuously updated purification techniques and identification methods are extremely important. In addition to their potential as cancer biomarkers, exosomes also provide new research directions for precision medicine. Currently, exosomes have potential value in disease treatment and provide clinicians with more meaningful judgment standards.

CDH6-activated αIIbβ3 crosstalks with α2β1 to trigger cellular adhesion and invasion in metastatic ovarian and renal cancers

Cadherin 6 (CDH6) is significantly overexpressed in advanced ovarian and renal cancers. However, the role of CDH6 in cancer metastasis is largely unclear. Here, we investigated the impact of CDH6 expression on integrin-mediated metastatic progression. CDH6 preferentially bound to αIIbβ3 integrin, a platelet receptor scarcely expressed in cancer cells, and this interaction was mediated through the cadherin Arginine-glycine-aspartic acid (RGD) motif. Furthermore, CDH6 and CDH17 were found to interact with α2β1 in αIIbβ3low cells. Transient silencing of CDH6, ITGA2B, or ITGB3 genes caused a significant loss of proliferation, adhesion, invasion, and lung colonization through the downregulation of SRC, FAK, AKT, and ERK signaling. In ovarian and renal cancer cells, integrin αIIbβ3 activation appears to be a prerequisite for proper α2β1 activation. Interaction of αIIbβ3 with CDH6, and subsequent αIIbβ3 activation, promoted activation of α2β1 and cell adhesion in ovarian and renal cancer cells. Additionally, monoclonal antibodies specific to the cadherin RGD motif and clinically approved αIIbβ3 inhibitors could block pro-metastatic activity in ovarian and renal tumors. In summary, the interaction between CDH6 and αIIbβ3 regulates α2β1-mediated adhesion and invasion of ovarian and renal cancer metastatic cells and constitutes a therapeutic target of broad potential for treating metastatic progression.

The Influence of VE-Cadherin on Adhesion and Incorporation of Breast Cancer Cells into Vascular Endothelium

During metastasis, cancer cells that originate from the primary tumor circulate in the bloodstream, extravasate, and form micrometastases at distant locations. Several lines of evidence suggest that specific interactions between cancer cells and endothelial cells, in particular tumor cell adhesion to the endothelium and transendothelial migration, play a crucial role in extravasation. Here we have studied the role of vascular endothelial (VE)-cadherin which is expressed aberrantly by breast cancer cells and might promote such interactions. By comparing different human breast cancer cell lines, we observed that the number of cancer cells that adhered to endothelium correlated with VE-cadherin expression levels. VE-cadherin silencing experiments confirmed that VE-cadherin enhances cancer cell adhesion to endothelial cells. However, in contrast, the number of cancer cells that incorporated into the endothelium was not dependent on VE-cadherin. Thus, it appears that cancer cell adhesion and incorporation are distinct processes that are governed by different molecular mechanisms. When cancer cells incorporated into the endothelial monolayer, they formed VE-cadherin positive contacts with endothelial cells. On the other hand, we also observed tumor cells that had displaced endothelial cells, reflecting either different modes of incorporation, or a temporal sequence where cancer cells first form contact with endothelial cells and then displace them to facilitate transmigration. Taken together, these results show that VE-cadherin promotes the adhesion of breast cancer cells to the endothelium and is involved in the initial phase of incorporation, but not their transmigration. Thus, VE-cadherin might be of relevance for therapeutic strategies aiming at preventing the metastatic spread of breast cancer cells.

Jatrorrhizine: a review of its pharmacological effects

OBJECTIVES

Jatrorrhizine is an isoquinoline alkaloid found in medicinal plants. It is the main bioactive compound of the Chinese herbs, Coptis chinensis, Rhizoma coptidis, and Phellodendron chinense Schneid, plants that are predominantly used in traditional Chinese medicine (TCM) for the treatment of metabolic disorders, gastritis, stomachache among a host of others. This manuscript aims to provide a comprehensive review of the pharmacological effects of jatrorrhizine, proffer suggestions on research areas that need redress and potentially serve as a reference for future studies.

KEY FINDINGS

Published scientific literature was therefore retrieved from all credible sources including Pubmed, Elsevier, Research Gate, Web of Science, Google Scholar, Science Direct, Europe PMC and Wiley Online library using key words such as 'jatrorrhizine', 'botanical sources', 'pharmacology', 'toxicology', 'pharmacokinetics' or their combinations. A cursory examination of relevant scientific literature using the aforementioned key words produced more than 400 publications.

CONCLUSIONS

Using an inclusion/exclusion criteria the subject matter of this review was adequately addressed. It is our hope that this review will provide a good platform for further research on fully harnessing the potential of this bioactive compound.

The Overexpression of Acyl-CoA Medium-Chain Synthetase-3 (ACSM3) Suppresses the Ovarian Cancer Progression via the Inhibition of Integrin β1/AKT Signaling Pathway

Ovarian cancer is considered as one of the most fatal gynecologic malignancies. This work aimed to explore the effects and regulatory mechanism of Acyl-CoA medium-chain synthetase-3 (ACSM3, a subunit of CoA ligases) in ovarian cancer progression. As well as employing CCK-8 assay, clone formation assay, and cell cycle analysis were carried out to investigate cell proliferation ability. Wound healing assay and transwell assay were subsequently used to assess cell migration and invasion. Mice xenografts were then conducted to measure the effects of ACSM3 on tumor development in vivo. Our bioinformatics analysis suggested that the expression of ACSM3 was down-regulated in ovarian cancer tissues, and the low expression level of ACSM3 might related with poorer overall survival than high mRNA expression of ACSM3 in ovarian cancer patients. We artificially regulated the expression of ACSM3 to evaluate its effects on ovarian cancer malignant phenotypes. Our data revealed that the overexpression of ACSM3 inhibited cell proliferation, migration, and invasion of ovarian cancer cells. In contrast, the knock-down of ACSM3 received the opposite results. Our western blot results showed that the Integrin β1/AKT signaling pathway was negatively regulated by ACSM3 expression. Moreover, ACSM3 overexpression-induced suppression of cell migration and invasion activities were abolished by the overexpression of ITG β1 (Integrin β1). Additionally, the growth of ovarian cancer xenograft tumors was also repressed by the overexpression of ACSM3. And ACSM3 interference obtained the contrary effects in vivo. In summary, ACSM3 acts as a tumor suppressor gene and may be a potential therapeutic target of ovarian cancer.

Exploiting the Natural Properties of Extracellular Vesicles in Targeted Delivery towards Specific Cells and Tissues

Extracellular vesicles (EVs) are important mediators of intercellular communication that participate in many physiological/pathological processes. As such, EVs have unique properties related to their origin, which can be exploited for drug delivery applications in cell regeneration, immunosuppression, inflammation, cancer treatment or cardioprotection. Moreover, their cell-like membrane organization facilitates uptake and accumulation in specific tissues and organs, which can be exploited to improve selectivity of cargo delivery. The combination of these properties with the inclusion of drugs or imaging agents can significantly improve therapeutic efficacy and selectivity, reduce the undesirable side effects of drugs or permit earlier diagnosis of diseases. In this review, we will describe the natural properties of EVs isolated from different cell sources and discuss strategies that can be applied to increase the efficacy of targeting drugs or other contents to specific locations. The potential risks associated with the use of EVs will also be addressed.

Gene co-expression and histone modification signatures are associated with melanoma progression, epithelial-to-mesenchymal transition, and metastasis

BACKGROUND

We have previously developed a murine cellular system that models the transformation from melanocytes to metastatic melanoma cells. This model was established by cycles of anchorage impediment of melanocytes and consists of four cell lines: differentiated melanocytes (melan-a), pre-malignant melanocytes (4C), malignant (4C11-), and metastasis-prone (4C11+) melanoma cells. Here, we searched for transcriptional and epigenetic signatures associated with melanoma progression and metastasis by performing a gene co-expression analysis of transcriptome data and a mass-spectrometry-based profiling of histone modifications in this model.

RESULTS

Eighteen modules of co-expressed genes were identified, and some of them were associated with melanoma progression, epithelial-to-mesenchymal transition (EMT), and metastasis. The genes in these modules participate in biological processes like focal adhesion, cell migration, extracellular matrix organization, endocytosis, cell cycle, DNA repair, protein ubiquitination, and autophagy. Modules and hub signatures related to EMT and metastasis (turquoise, green yellow, and yellow) were significantly enriched in genes associated to patient survival in two independent melanoma cohorts (TCGA and Leeds), suggesting they could be sources of novel prognostic biomarkers. Clusters of histone modifications were also linked to melanoma progression, EMT, and metastasis. Reduced levels of H4K5ac and H4K8ac marks were seen in the pre-malignant and tumorigenic cell lines, whereas the methylation patterns of H3K4, H3K56, and H4K20 were related to EMT. Moreover, the metastatic 4C11+ cell line showed higher H3K9me2 and H3K36me3 methylation, lower H3K18me1, H3K23me1, H3K79me2, and H3K36me2 marks and, in agreement, downregulation of the H3K36me2 methyltransferase Nsd1.

CONCLUSIONS

We uncovered transcriptional and histone modification signatures that may be molecular events driving melanoma progression and metastasis, which can aid in the identification of novel prognostic genes and drug targets for treating the disease.

Vascular mimicry: Triggers, molecular interactions and in vivo models

Vascular mimicry is induced by a wide array of genes with functions related to cancer stemness, hypoxia, angiogenesis and autophagy. Vascular mimicry competent (VM-competent) cells that form de novo blood vessels are common in solid tumors facilitating tumor cell survival and metastasis. VM-competent cells display increased levels of vascular mimicry selecting for stem-like cells in an O₂-gradient-dependent manner in deeply hypoxic tumor regions, while also aiding in maintaining tumor cell metabolism and stemness. Three of the principal drivers of vascular mimicry are EphA2, Nodal and HIF-1α, however, directly or indirectly many of these molecules affect VE-Cadherin (VE-Cad), which forms gap-junctions to bind angiogenic blood vessels together. During vascular mimicry, the endothelial-like functions of VM-competent cancer stem cells co-opt VE-Cad to bind cancer cells together to create cancer cell-derived blood conducting vessels. This process potentially compensates for the lack of access to blood and nutrient in avascular tumors, simultaneously providing nutrients and enhancing cancer invasion and metastasis. Current evidence also supports that vascular mimicry promotes cancer malignancy and metastasis due to the cooperation of oncogenic signaling molecules driving cancer stemness and autophagy. While a number of currently used cancer therapeutics are effective inhibitors of vascular mimicry, developing a new class of vascular mimicry specific inhibitors could allow for the treatment of angiogenesis-resistant tumors, inhibit cancer metastasis and improve patient survival. In this review, we describe the principal vascular mimicry pathways in addition to emphasizing the roles of hypoxia, autophagy and select proangiogenic oncogenes in this process.

The G Protein-Coupled Estrogen Receptor (GPER) Expression Correlates with Pro-Metastatic Pathways in ER-Negative Breast Cancer: A Bioinformatics Analysis

The G protein-coupled estrogen receptor (GPER, formerly known as GPR30) is a seven-transmembrane receptor that mediates estrogen signals in both normal and malignant cells. In particular, GPER has been involved in the activation of diverse signaling pathways toward transcriptional and biological responses that characterize the progression of breast cancer (BC). In this context, a correlation between GPER expression and worse clinical-pathological features of BC has been suggested, although controversial data have also been reported. In order to better assess the biological significance of GPER in the aggressive estrogen receptor (ER)-negative BC, we performed a bioinformatics analysis using the information provided by The Invasive Breast Cancer Cohort of The Cancer Genome Atlas (TCGA) project and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) datasets. Gene expression correlation and the statistical analysis were carried out with R studio base functions and the tidyverse package. Pathway enrichment analysis was evaluated with Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway on the Database for Annotation, Visualization and Integrated Discovery (DAVID) website, whereas gene set enrichment analysis (GSEA) was performed with the R package phenoTest. The survival analysis was determined with the R package survivALL. Analyzing the expression data of more than 2500 primary BC, we ascertained that GPER levels are associated with pro-migratory and metastatic genes belonging to cell adhesion molecules (CAMs), extracellular matrix (ECM)-receptor interaction, and focal adhesion (FA) signaling pathways. Thereafter, evaluating the disease-free interval (DFI) in ER-negative BC patients, we found that the subjects expressing high GPER levels exhibited a shorter DFI in respect to those exhibiting low GPER levels. Overall, our results may pave the way to further dissect the network triggered by GPER in the breast malignancies lacking ER toward a better assessment of its prognostic significance and the action elicited in mediating the aggressive features of the aforementioned BC subtype.

A Review on Targeting Nanoparticles for Breast Cancer

Chemotherapeutic agents have been used extensively in breast cancer remedy. However, most anticancer drugs cannot differentiate between cancer cells and normal cells, leading to toxic side effects. Also, the resulted drug resistance during chemotherapy reduces treatment efficacy. The development of targeted drug delivery offers great promise in breast cancer treatment both in clinical applications and in pharmaceutical research. Conjugation of nanocarriers with targeting ligands is an effective therapeutic strategy to treat cancer diseases. In this review, we focus on active targeting methods for breast cancer cells through the use of chemical ligands such as antibodies, peptides, aptamers, vitamins, hormones, and carbohydrates. Also, this review covers all information related to these targeting ligands, such as their subtypes, advantages, disadvantages, chemical modification methods with nanoparticles and recent published studies (from 2015 to present). We have discussed 28 different targeting methods utilized for targeted drug delivery to breast cancer cells with different nanocarriers delivering anticancer drugs to the tumors. These different targeting methods give researchers in the field of drug delivery all the information and techniques they need to develop modern drug delivery systems.

Exosomes released upon mitochondrial ASncmtRNA knockdown reduce tumorigenic properties of malignant breast cancer cells

During intercellular communication, cells release extracellular vesicles such as exosomes, which contain proteins, ncRNAs and mRNAs that can influence proliferation and/or trigger apoptosis in recipient cells, and have been proposed to play an essential role in promoting invasion of tumor cells and in the preparation of metastatic niches. Our group proposed the antisense non-coding mitochondrial RNA (ASncmtRNA) as a new target for cancer therapy. ASncmtRNA knockdown using an antisense oligonucleotide (ASO-1537S) causes massive death of tumor cells but not normal cells and strongly reduces metastasis in mice. In this work, we report that exosomes derived from ASO-1537S-treated MDA-MB-231 breast cancer cells (Exo-1537S) inhibits tumorigenesis of recipient cells, in contrast to exosomes derived from control-ASO-treated cells (Exo-C) which, in contrast, enhance these properties. Furthermore, an in vivo murine peritoneal carcinomatosis model showed that Exo-1537S injection reduced tumorigenicity compared to controls. Proteomic analysis revealed the presence of Lactadherin and VE-Cadherin in exosomes derived from untreated cells (Exo-WT) and Exo-C but not in Exo-1537S, and the latter displayed enrichment of proteasomal subunits. These results suggest a role for these proteins in modulation of tumorigenic properties of exosome-recipient cells. Our results shed light on the mechanisms through which ASncmtRNA knockdown affects the preparation of breast cancer metastatic niches in a peritoneal carcinomatosis model.

Melanoma Metabolism: Cell Survival and Resistance to Therapy

Cutaneous melanoma is one of the most aggressive types of cancer, presenting the highest potential to form metastases, both locally and distally, which are associated with high death rates of melanoma patients. A high somatic mutation burden is characteristic of these tumours, with most common oncogenic mutations occurring in the BRAF, NRAS and NF1 genes. These intrinsic oncogenic pathways contribute to the metabolic switch between glycolysis and oxidative phosphorylation metabolisms of melanoma, facilitating tumour progression and resulting in a high plasticity and adaptability to unfavourable conditions. Moreover, melanoma microenvironment can influence its own metabolism and reprogram several immune cell subset functions, enabling melanoma to evade the immune system. The knowledge of the biology, molecular alterations and microenvironment of melanoma has led to the development of new targeted therapies and the improvement of patient care. In this work, we reviewed the impact of melanoma metabolism in the resistance to BRAF and MEK inhibitors and immunotherapies, emphasizing the requirement to evaluate metabolic alterations upon development of novel therapeutic approaches. Here we summarized the current understanding of the impact of metabolic processes in melanomagenesis, metastasis and microenvironment, as well as the involvement of metabolic pathways in the immune modulation and resistance to targeted and immunocheckpoint therapies.

Cadherin Signaling in Cancer: Its Functions and Role as a Therapeutic Target

Cadherin family includes lists of transmembrane glycoproteins which mediate calcium-dependent cell-cell adhesion. Cadherin-mediated adhesion regulates cell growth and differentiation throughout life. Through the establishment of the cadherin-catenin complex, cadherins provide normal cell-cell adhesion and maintain homeostatic tissue architecture. In the process of cell recognition and adhesion, cadherins act as vital participators. As results, the disruption of cadherin signaling has significant implications on tumor formation and progression. Altered cadherin expression plays a vital role in tumorigenesis, tumor progression, angiogenesis, and tumor immune response. Based on ongoing research into the role of cadherin signaling in malignant tumors, cadherins are now being considered as potential targets for cancer therapies. This review will demonstrate the mechanisms of cadherin involvement in tumor progression, and consider the clinical significance of cadherins as therapeutic targets.

Beyond N-Cadherin, Relevance of Cadherins 5, 6 and 17 in Cancer Progression and Metastasis

Cell-cell adhesion molecules (cadherins) and cell-extracellular matrix adhesion proteins (integrins) play a critical role in the regulation of cancer invasion and metastasis. Although significant progress has been made in the characterization of multiple members of the cadherin superfamily, most of the published work continues to focus in the switch E-/N-cadherin and its role in the epithelial-mesenchymal transition. Here, we will discuss the structural and functional properties of a subset of cadherins (cadherin 17, cadherin 5 and cadherin 6) that have an RGD motif in the extracellular domains. This RGD motif is critical for the interaction with α2β1 integrin and posterior integrin pathway activation in cancer metastatic cells. However, other signaling pathways seem to be affected by RGD cadherin interactions, as will be discussed. The range of solid tumors with overexpression or "de novo" expression of one or more of these three cadherins is very wide (gastrointestinal, gynaecological and melanoma, among others), underscoring the relevance of these cadherins in cancer metastasis. Finally, we will discuss different evidences that support the therapeutic use of these cadherins by blocking their capacity to work as integrin ligands in order to develop new cures for metastatic patients.

Dynamic of VE-cadherin-mediated spermatid-Sertoli cell contacts in the mouse seminiferous epithelium

Spermatids are haploid differentiating cells that, in the meantime they differentiate, translocate along the seminiferous epithelium towards the tubule lumen to be just released as spermatozoa. The success of such a migration depends on dynamic of spermatid-Sertoli cell contacts, the molecular nature of which has not been well defined yet. It was demonstrated that the vascular endothelial cadherin (VEC) is expressed transitorily in the mouse seminiferous epithelium. Here, we evaluated the pattern of VEC expression by immunohistochemistry first in seminiferous tubules at different stages of the epithelial cycle when only unique types of germ cell associations are present. Changes in the pattern of VEC localization according to the step of spermatid differentiation were analysed in detail using testis fragments and spontaneously released germ cells. Utilizing the first wave of spermatogenesis as an in vivo model to have at disposal spermatids at progressive steps of differentiation, we checked for level of looser VEC association with the membrane by performing protein solubilisation under mild detergent conditions and assays through VEC-immunoblotting. Being changes in VEC solubilisation paralleled in changes in phosphotyrosine (pY) content, we evaluated if spermatid VEC undergoes Y658 phosphorylation and if this correlates with VEC solubilisation and spermatid progression in differentiation. Altogether, our study shows a temporally restricted pattern of VEC expression that culminates with the presence of round spermatids to progressively decrease starting from spermatid elongation. Conversely, pY658-VEC signs elongating spermatids; its intracellular polarized compartmentalization suggests a possible involvement of pY658-VEC in the acquisition of spermatid cell polarity.

Integrins as therapeutic targets in the organ-specific metastasis of human malignant melanoma

Integrins are a large family of adhesion molecules that mediate cell-cell and cell-extracellular matrix interactions. Among the 24 integrin isoforms, many have been found to be associated with tumor angiogenesis, tumor cell migration and proliferation, and metastasis. Integrins, especially αvβ3, αvβ5 and α5β1, participate in mediating tumor angiogenesis by interacting with the vascular endothelial growth factor and angiopoietin-Tie signaling pathways. Melanoma patients have a poor prognosis when the primary tumor has generated distant metastases, and the melanoma metastatic site is an independent predictor of the survival of these patients. Different integrins on the melanoma cell surface preferentially direct circulating melanoma cells to different organs and promote the development of metastases at specific organ sites. For instance, melanoma cells expressing integrin β3 tend to metastasize to the lungs, whereas those expressing integrin β1 preferentially generate lymph node metastases. Moreover, tumor cell-derived exosomes which contain different integrins may prepare a pre-metastatic niche in specific organs and promote organ-specific metastases. Because of the important role that integrins play in tumor angiogenesis and metastasis, they have become promising targets for the treatment of advanced cancer. In this paper, we review the integrin isoforms responsible for angiogenesis and organ-specific metastasis in malignant melanoma and the inhibitors that have been considered for the future treatment of metastatic disease.

The Expression and Functional Significance of Vascular Endothelial-Cadherin, CD44, and Vimentin in Oral Squamous Cell Carcinoma

Objectives

Ninety percent of head and neck cancers are squamous cell carcinoma which develops in the oral cavity. Metastasis is the main causative factor for death in 90% of all cancer-related deaths and begins with the invasion of tumor cells through the walls of small blood vessels or lymph vessels. A growing body of evidence has shown that vasculogenic mimicry (VM) facilitates tumor growth and cancer metastasis. The current study aimed to present the role of vascular endothelial (VE)-cadherin, CD44, and vimentin in inducing VM and epithelial-mesenchymal transition (EMT) and to identify the cancer stem cell (CSC) niche in different grades of oral squamous cell carcinoma (OSCC).

Materials and Methods

A total of 63 OSCC samples (21 samples each grade) were collected from the archive of Pathology Department of Besat educational hospital, Hamadan, Iran, from 2000 to 2015. VE-cadherin, CD44, and vimentin/periodic acid-Schiff (PAS) double-staining were used to validate VM. VM was identified by the detection of PAS-positive loops surrounded by tumor cells. Chi-square test was used to examine the differences between the variables. Significant level was set at 0.05. Pearson's correlation was used to assess the co-localization of the markers.

Results

There were statistically significant differences between tumor grade and the expression levels of VE-cadherin, CD44, and vimentin (P = 0.000). In addition, significant differences were found between tumor grade and microvessel density (P = 0.000) and between tumor grade and VM (P = 0.000).

Conclusion

Our results may disclose a definite relationship between VE-cadherin, CD44 and vimentin expression levels, VM formation, EMT, CSCs, and microvessel count in OSCC samples. For this reason, it is suggested that VE-cadherin, CD44, and vimentin are related to angiogenesis and VM formation in OSCC, therefore, in tumor progression and metastasis. Recently, antitumor angiogenic therapies have been challenged. The presence of VM may explain the failure of antiangiogenic treatments.

HIF-2α promotes the formation of vasculogenic mimicry in pancreatic cancer by regulating the binding of Twist1 to the VE-cadherin promoter

Vasculogenic mimicry (VM) is a blood supply modality that occurs independently of endothelial cell angiogenesis. Hypoxia and the epithelial-mesenchymal transition (EMT) induce VM formation by remodeling the extracellular matrix. Our previous study demonstrated that hypoxia-inducible factor-2 alpha (HIF-2α) promotes the progress of EMT in pancreatic cancer; however, whether HIF-2α promotes VM formation in pancreatic cancer remains unknown. In this study, we investigated HIF-2α expression and VM by immunohistochemistry in 70 pancreatic cancer patients as well as the role of Twist1and Twist2 in HIF-2α-induced VM in vitro and in vivo. We found that the overexpression of HIF-2α and VM were correlated with poor tumor differentiation, late clinical stage and lymph node metastasis, and a poor prognosis in pancreatic cancer. Moreover, the upregulation of HIF-2α in SW1990 cells induced VM formation, whereas the opposite results were found after silencing HIF-2α in AsPC-1 cells. A mechanistic study indicated that HIF-2α might regulate the binding of twist1 to vascular endothelial cadherin (VE-cadherin) to promote VM formation in pancreatic cancer cells, and that the P1 (-421bp) and P4 (-2110bp) regions of the Twist1 binding sequences are positive regulatory elements for VE-cadherin. In addition, we confirmed that the overexpression of HIF-2α increased Twist1 expression and promoted tumor growth and VM formation in pancreatic cancer xenografts in nude mice. These findings indicated that HIF-2α might play a critical role in VM and that HIF-2α and the pathway of HIF-2α inducing VM formation are potential therapeutic targets for pancreatic cancer.

RGD cadherins and α2β1 integrin in cancer metastasis: A dangerous liaison

We propose a new cadherin family classification comprising epithelial cadherins (cadherin 17 [CDH17], cadherin 16, VE-cadherin, cadherin 6 and cadherin 20) containing RGD motifs within their sequences. Expression of some RGD cadherins is associated with aggressive forms of cancer during the late stages of metastasis, and CDH17 and VE-cadherin have emerged as critical actors in cancer metastasis. After binding to α2β1 integrin, these cadherins promote integrin β1 activation, and thereby cell adhesion, invasion and proliferation, in liver and lung metastasis. Activation of α2β1 integrin provokes an affinity increase for type IV collagen, a major component of the basement membrane and a critical partner for cell anchoring in liver and other metastatic organs. Activation of α2β1 integrin by RGD motifs breaks an old paradigm of integrin classification and supports an important role of this integrin in cancer metastasis. Recently, synthetic peptides containing the RGD motif of CDH17 elicited highly specific and selective antibodies that block the ability of CDH17 RGD to activate α2β1 integrin. These monoclonal antibodies inhibit metastatic colonization in orthotopic mouse models of liver and lung metastasis for colorectal cancer and melanoma, respectively. Hopefully, blocking the cadherin RGD ligand capacity will give us control over the integrin activity in solid tumors metastasis, paving the way for development of new agents of cancer treatment.

The tyrosine-kinase inhibitor sunitinib targets vascular endothelial (VE)-cadherin: a marker of response to antitumoural treatment in metastatic renal cell carcinoma

Background

Vascular endothelial (VE)-cadherin is an endothelial cell-specific protein responsible for endothelium integrity. Its adhesive properties are regulated by post-translational processing, such as tyrosine phosphorylation at site Y⁶⁸⁵ in its cytoplasmic domain, and cleavage of its extracellular domain (sVE). In hormone-refractory metastatic breast cancer, we recently demonstrated that sVE levels correlate to poor survival. In the present study, we determine whether kidney cancer therapies had an effect on VE-cadherin structural modifications and their clinical interest to monitor patient outcome.

Methods

The effects of kidney cancer biotherapies were tested on an endothelial monolayer model mimicking the endothelium lining blood vessels and on a homotypic and heterotypic 3D cell model mimicking tumour growth. sVE was quantified by ELISA in renal cell carcinoma patients initiating sunitinib (48 patients) or bevacizumab (83 patients) in the first-line metastatic setting (SUVEGIL and TORAVA trials).

Results

Human VE-cadherin is a direct target for sunitinib which inhibits its VEGF-induced phosphorylation and cleavage on endothelial monolayer and endothelial cell migration in the 3D model. The tumour cell environment modulates VE-cadherin functions through MMPs and VEGF. We demonstrate the presence of soluble VE-cadherin in the sera of mRCC patients (n = 131) which level at baseline, is higher than in a healthy donor group (n = 96). Analysis of sVE level after 4 weeks of treatment showed that a decrease in sVE level discriminates the responders vs. non-responders to sunitinib, but not bevacizumab.

Conclusions

These data highlight the interest for the sVE bioassay in future follow-up of cancer patients treated with targeted therapies such as tyrosine-kinase inhibitors.

Expression of Vascular Endothelial-Cadherin in Mucoepidermoid Carcinoma: Role in Cancer Development

Objectives:

Mucoepidermoid carcinoma (MEC) accounts for 35% of all malignant salivary gland tumors. Previous investigations have shown that vasculogenic mimicry (VM) exists in many cancers which can be used as a prognostic factor of poor prognosis. Elevated expression level of vascular endothelial (VE)-cadherin has been implicated in cancer neovascularization, growth, and progression. The current study aimed to study the presence of VE-cadherin in VM channels and tumor cells in different grades of MEC.

Materials and Methods:

A total of 63 MEC samples (21 samples in each grade) were collected from the archive of pathology department of Besat Educational Hospital, Hamadan, Iran, from 2002 to 2016. Hematoxylin and eosin staining was performed to confirm the previous diagnosis. The specimens were then processed for immunohistochemistry analysis. Then, periodic acid–Schiff staining was performed. Analyses were conducted through SPSS software version 22.0 (SPSS, Inc., Chicago, IL, USA). Chi-square test was used to examine the differences between categorical variables. Significance level was set at 0.05. Pearson's correlation was used to assess the co-localization of the marker.

Results:

A total of 63 samples (35 men; 55.6%, and 28 women; 44.4%) were used for immunohistochemical study. There were statistically significant differences between tumor grade and the expression levels of VE-cadherin (P = 0.000), between tumor grade and VM formation (P = 0.000), and also between tumor grade and microvessel density (MVD) (P = 0.000). Additionally, there was a strong positive correlation between tumor grade and VE-cadherin expression level (Pearson's r = 0.875, P < 0.000).

Conclusions:

Our results may disclose a definite relationship between VE-cadherin expression level, VM, epithelial–mesenchymal transition, cancer stem cells, and MVD in MEC samples. Thus, it is reasonable to suggest that VE-cadherin is related to angiogenesis and VM formation in MECs.

Monoclonal Antibodies Directed against Cadherin RGD Exhibit Therapeutic Activity against Melanoma and Colorectal Cancer Metastasis

Purpose: New targets are required for the control of advanced metastatic disease. We investigated the use of cadherin RGD motifs, which activate the α2β1integrin pathway, as targets for the development of therapeutic monoclonal antibodies (mAb).Experimental Design: Cadherin 17 (CDH17) fragments and peptides were prepared and used for immunization and antibody development. Antibodies were tested for inhibition of β1 integrin and cell adhesion, proliferation, and invasion assays using cell lines from different cancer types (colorectal, pancreatic, melanoma, and breast cancer). Effects of the mAbs on cell signaling were determined by Western blot analysis. Nude mice were used for survival analysis after treatment with RGD-specific mAbs and metastasis development.Results: Antibodies against full-length CDH17 failed to block the binding to α2β1 integrin. However, CDH17 RGD peptides generated highly selective RGD mAbs that blocked CDH17 and vascular-endothelial (VE)-cadherin-mediated β1 integrin activation in melanoma and breast, pancreatic, and colorectal cancer cells. Antibodies provoked a significant reduction in cell adhesion and proliferation of metastatic cancer cells. Treatment with mAbs impaired the integrin signaling pathway activation of FAK in colorectal cancer, of JNK and ERK kinases in colorectal and pancreatic cancers, and of JNK, ERK, Src, and AKT in melanoma and breast cancer. In vivo, RGD-specific mAbs increased mouse survival after inoculation of melanoma and colorectal cancer cell lines to cause lung and liver metastasis, respectively.Conclusions: Blocking the interaction between RGD cadherins and α2β1 integrin with highly selective mAbs constitutes a promising therapy against advanced metastatic disease in colon cancer, melanoma, and, potentially, other cancers. Clin Cancer Res; 24(2); 433-44. ©2017 AACRSee related commentary by Marshall, p. 253.