Nectin family of cell-adhesion molecules: structural and molecular aspects of function and specificity

The Systematic Landscape of Nectin Family and Nectin-Like Molecules: Functions and Prognostic Value in Low Grade Glioma

Objective: Nectin and nectin-like molecules (Necls) are molecules that are involved in cell–cell adhesion and other vital cellular processes. This study aimed to determine the expression and prognostic value of nectin and Necls in low grade glioma (LGG).

Materials and Methods: Differentially expressed nectin and Necls in LGG samples and the relationship of nectin family and Necls expression with prognosis, clinicopathological parameters, and survival were explored using The Cancer Genome Atlas (TCGA), the Chinese Glioma Genome Atlas (CGGA), and Repository of Molecular Brain Neoplasia Data (REMBRANDT) databases. Univariate and multivariate Cox analysis models were performed to construct the prognosis-related gene signature. Kaplan-Meier curves and time-dependent receiver operating characteristic (ROC) curves and multivariate Cox regression analysis, were utilized to evaluate the prognostic capacity of the four-gene signature. Gene ontology (GO)enrichment analysis and Gene Set Enrichment Analyses (GSEA) were performed to further understand the underlying molecular mechanisms. The Tumor Immune Estimation Resource (TIMER) was used to explore the relationship between the four-gene signature and tumor immune infiltration.

Results: Several nectin and Necls were differentially expressed in LGG. Kaplan–Meier survival analyses and Univariate Cox regression showed patients with high expression of NECTIN2 and PVR and low expression of CADM2 and NECTIN1 had worse prognosis among TCGA, CGGA, and REMBRANDT database. Then, a novel four-gene signature was built for LGG prognosis prediction. ROC curves, KM survival analyses, and multivariate COX regression indicated the new signature was an independent prognostic indicator for overall survival. Finally, GSEA and GO enrichment analyses revealed that immune-related pathways participate in the molecular mechanisms. The risk score had a strong negative correlation with tumor purity and data of TIMER showed different immune cell proportions (macrophage and myeloid dendritic cell) between high- and low-risk groups. Additionally, signature scores were positively related to multiple immune-related biomarkers (IL 2, IL8 and IFNγ).

Conclusion: Our results offer an extensive analysis of nectin and Necls levels and a four-gene model for prognostic prediction in LGG, providing insights for further investigation of CADM2, NECTIN1/2, and PVR as potential clinical and immune targets in LGG.

Nectin cell adhesion molecule-4 (NECTIN-4): A potential target for cancer therapy

NECTIN-4 [a poliovirus receptor-related-4 (pvrl-4) encoded protein] is a Ca2+ independent immunoglobulin-like protein. Along with other Nectins (Nectin-1, -2 and -3), it is primarily involved in cell-cell adhesion. In contrast to other Nectins, Nectin-4 is specifically enriched in the embryonic and placental tissues but its expression significantly declines in adult life. In recent years, it has been found that Nectin-4 is especially overexpressed and served as a tumor associated inducer in various malignant tumors including breast, lung, colorectal, pancreatic, ovarian cancers etc. Over-expression of Nectin-4 is associated with various aspects of tumor progression like proliferation, angiogenesis, epithelial to mesenchymal transition, metastasis, DNA repair, tumor relapse, poor prognosis in several types of cancer. This review systematically highlights the implications of Nectin-4 in every possible aspect of cancer and the molecular mechanism of Nectin-4 mediated cancer progression. We have further emphasized on the therapeutic strategies that are being proposed to specifically target Nectin-4.

BT7480, a novel fully synthetic Bicycle tumor-targeted immune cell agonist™ (Bicycle TICA™) induces tumor localized CD137 agonism

Background

CD137 (4-1BB) is an immune costimulatory receptor with high therapeutic potential in cancer. We are creating tumor target-dependent CD137 agonists using a novel chemical approach based on fully synthetic constrained bicyclic peptide (Bicycle®) technology. Nectin-4 is overexpressed in multiple human cancers that may benefit from CD137 agonism. To this end, we have developed BT7480, a novel, first-in-class, Nectin-4/CD137 Bicycle tumor-targeted immune cell agonist™ (Bicycle TICA™).

Methods

Nectin-4 and CD137 co-expression analyses in primary human cancer samples was performed. Chemical conjugation of two CD137 Bicycles to a Nectin-4 Bicycle led to BT7480, which was then evaluated using a suite of in vitro and in vivo assays to characterize its pharmacology and mechanism of action.

Results

Transcriptional profiling revealed that Nectin-4 and CD137 were co-expressed in a variety of human cancers with high unmet need and spatial proteomic imaging found CD137-expressing immune cells were deeply penetrant within the tumor near Nectin-4-expressing cancer cells. BT7480 binds potently, specifically, and simultaneously to Nectin-4 and CD137. In co-cultures of human peripheral blood mononuclear cells and tumor cells, this co-ligation causes robust Nectin-4-dependent CD137 agonism that is more potent than an anti-CD137 antibody agonist. Treatment of immunocompetent mice bearing Nectin-4-expressing tumors with BT7480 elicited a profound reprogramming of the tumor immune microenvironment including an early and rapid myeloid cell activation that precedes T cell infiltration and upregulation of cytotoxicity-related genes. BT7480 induces complete tumor regressions and resistance to tumor re-challenge. Importantly, antitumor activity is not dependent on continuous high drug levels in the plasma since a once weekly dosing cycle provides maximum antitumor activity despite minimal drug remaining in the plasma after day 2. BT7480 appears well tolerated in both rats and non-human primates at doses far greater than those expected to be clinically relevant, including absence of the hepatic toxicity observed with non-targeted CD137 agonists.

Conclusion

BT7480 is a highly potent Nectin-4-dependent CD137 agonist that produces complete regressions and antitumor immunity with only intermittent drug exposure in syngeneic mouse tumor models and is well tolerated in preclinical safety species. This work supports the clinical investigation of BT7480 for the treatment of cancer in humans.

Role of Nectin‑4 protein in cancer (Review)

The Nectin cell adhesion molecule (Nectin) family members are Ca2+‑independent immunoglobulin‑like cellular adhesion molecules (including Nectins 1‑4), involved in cell adhesion via homophilic/heterophilic interplay. In addition, the Nectin family plays a significant role in enhancing cellular viability and movement ability. In contrast to enrichment of Nectins 1‑3 in normal tissues, Nectin‑4 is particularly overexpressed in a number of tumor types, including breast, lung, urothelial, colorectal, pancreatic and ovarian cancer. Moreover, the upregulation of Nectin‑4 is an independent biomarker for overall survival in numerous cancer types. A large number of studies have revealed that high expression of Nectin‑4 is closely related to tumor occurrence and development in various cancer types, but the manner in which Nectin‑4 protein contributes to the onset and development of these malignancies is yet unknown. The present review summarizes the molecular mechanisms and functions of Nectin‑4 protein in the biological processes and current advances with regard to its expression and regulation in various cancer types.

Platelet-mediated tumor metastasis mechanism and the role of cell adhesion molecules

Mounting evidence suggests that platelets play an essential role in cancer metastasis. The interactions between platelets and circulating tumor cells (CTCs) promote cancer metastasis. CTCs induce platelet activation and aggregation, and activated platelets gather and protect CTCs from shear stress and natural killer cells. Finally, platelets stimulate CTC anoikis resistance, epithelial-to-mesenchymal transition, angiogenesis, extravasation, and eventually, metastasis. Cell adhesion molecules (CAMs) have been identified as active players during the interaction of CTCs with platelets, but the specific mechanism underlying the contribution of platelet-associated CAMs to CTC metastasis remains unclear. In this review, we introduce the mechanism of platelet-related tumor metastasis and particularly focus on the role of CAMs in it.

Emerging bioadhesives: from traditional bioactive and bioinert to a new biomimetic protein-based approach

Bioadhesives have reached significant milestones over the past two decades. Research has shown not only to produce adhesives capable of adhering to dry tissue but recently wet tissue as well. However, most bioadhesives developed have exhibited high adhesion strength yet lack other properties required for versatility in application, such as elasticity, biocompatibility and biodegradability. Adapting from limitations met from early bioadhesives and meeting the current demand allows novel bioadhesives to reach new milestones for the future. In this review, we overview the progression and variations of bioadhesives, current trends, characterisation techniques and conclude with future perspectives for bioadhesives for tissue engineering applications.

The CD112R/CD112 axis: a breakthrough in cancer immunotherapy

The recent discovery of immune checkpoint inhibitors is a significant milestone in cancer immunotherapy research. However, some patients with primary or adaptive drug resistance might not benefit from the overall therapeutic potential of immunotherapy in oncology. Thus, it is becoming increasingly critical for oncologists to explore the availability of new immune checkpoint inhibitors. An emerging co-inhibitory receptor, CD112R (also called PVRIG), is most commonly expressed on natural killer (NK) and T cells. It binds to its ligand (CD112 or PVRL2/nectin-2) and inhibits the strength with which T cells and NK cells respond to cancer. Therefore, CD112R is being presented as a new immune checkpoint inhibitor with high potential in cancer immunotherapy. CD112 is easily detectable on antigen-presenting or tumor cells, and its high level of expression has been linked with tumor progression and poor outcomes in most cancer patients. This review explores the molecular and functional relationship between CD112R, TIGIT, CD96, and CD226 in T cell responses. In addition, this review comprehensively discusses the recent developments of CD112R/CD112 immune checkpoints in cancer immunotherapy and prognosis.

Expression of Nectin-4 in Bladder Urothelial Carcinoma, in Morphologic Variants, and Nonurothelial Histotypes

The antibody-drug conjugate enfortumab-vedotin acts by targeting nectin-4, a protein that is nearly ubiquitously expressed in conventional urothelial cancer. However, expression of nectin-4 in morphologic variants of urothelial carcinoma and nonurothelial histotypes was unknown. Immunohistochemistry for nectin-4 using was performed on 169 patients including 83 with nonmuscle invasive bladder cancer and 86 patients with muscle invasive bladder cancer. Staining was scored for intensity (0 to 3) and extent (% positive cells) using the histological score system, where >15 was considered positive. Overall, 72/83 (87%) samples of nonmuscle invasive urothelial carcinoma were positive, including 29/30 (97%) noninvasive papillary urothelial carcinomas, 7/8 (87.5%) carcinomas in situ, 36/45 (80%) papillary urothelial carcinomas invading the lamina propria. Overall, 50/86 muscle invasive tumors were positive, including 15/22 (68.2%) urothelial carcinomas, 7/10 (70%) squamous cell carcinomas, 3/11 (28%) micropapillary tumors, 4/6 (66%) adenocarcinomas, 2/4 (50%) nested carcinomas, 5/8 (63%) plasmacytoid, 1/10 (10%) sarcomatoid carcinomas, and 0/15 (0%) small cell carcinomas. Whole transcriptome RNA sequencing revealed that compared with conventional urothelial carcinomas, most sarcomatoid carcinomas and all but 2 small cell carcinomas expressed very low levels of nectin-4 mRNA but expressed significant levels of either trop2 or ERBB2, which are the molecular targets of 2 other antibody-drug conjugates-sacituzumab gavitecan (trop2) or trastuzumab deruxtecan (ERBB2/HER2). In summary, our study demonstrates that there is heterogeneity of expression of nectin-4 in morphologic variants of urothelial cancer and nonurothelial histotypes, and suggests that testing expression of nectin-4 should be considered in morphologic variants or nonurothelial histotypes found to have lower expression.

Immunoglobulin-fold containing bacterial adhesins: molecular and structural perspectives in host tissue colonization and infection

Immunoglobulin (Ig) domains are one of the most widespread protein domains encoded by the human genome and are present in a large array of proteins with diverse biological functions. These Ig domains possess a central structure, the immunoglobulin-fold, which is a sandwich of two β sheets, each made up of anti-parallel β strands, surrounding a central hydrophobic core. Apart from humans, proteins containing Ig-like domains are also distributed in a vast selection of organisms including vertebrates, invertebrates, plants, viruses and bacteria where they execute a wide array of discrete cellular functions. In this review, we have described the key structural deviations of bacterial Ig-folds when compared to the classical eukaryotic Ig-fold. Further, we have comprehensively grouped all the Ig-domain containing adhesins present in both Gram-negative and Gram-positive bacteria. Additionally, we describe the role of these particular adhesins in host tissue attachment, colonization and subsequent infection by both pathogenic and non-pathogenic Escherichia coli as well as other bacterial species. The structural properties of these Ig-domain containing adhesins, along with their interactions with specific Ig-like and non Ig-like binding partners present on the host cell surface have been discussed in detail.

Emerging roles of the nectin family of cell adhesion molecules in tumour-associated pathways

Tumour cells achieve maximum survival by modifying cellular machineries associated with processes such as cell division, migration, survival, and apoptosis, resulting in genetically complex and heterogeneous populations. While nectin and nectin-like cell adhesion molecules control development and maintenance of multicellular organisation in higher vertebrates by mediating cell-cell adhesion and related signalling processes, recent studies indicate that they also critically regulate growth and development of different types of cancers. In this review, we detail current knowledge about the role of nectin family members in various tumours. Furthermore, we also analyse the seemingly opposing roles of some members of nectin family in tumour-associated pathways, as they function as both tumour suppressors and oncogenes. Understanding this functional duality of nectin family in tumours will further our knowledge of molecular mechanisms regulating tumour development and progression, and contribute to the advancement of tumour diagnosis and therapy.

Targeting nectin-4 by antibody-drug conjugates for the treatment of urothelial carcinoma

INTRODUCTION

Nectin-4 is a tumor-associated antigen overexpressed in urothelial carcinoma and several other malignancies. It has emerged as a compelling target for novel tumor-directed therapies, particularly as a component of antibody-drug conjugates (ADCs), a growing class of anti-cancer therapeutic agents. Development of nectin-4-directed therapies has been led by enfortumab vedotin (EV), an ADC comprised of a fully human monoclonal antibody specific for nectin-4 conjugated via a cleavable linker to the microtubule inhibitor MMAE. EV was approved in 2019 as a first-in-class agent for the treatment of urothelial carcinoma.

AREAS COVERED

This article discusses general principles relevant to ADC design and our current understanding of nectin-4 in normal physiology and malignancy, followed by a review of the development of EV as well as additional drug conjugate strategies targeting nectin-4.

EXPERT OPINION

EV offers proof-of-concept for the clinical utility of nectin-4-directed therapies and provides further support for ADCs as an important class of anti-cancer agents. Future development of nectin-4-targeted approaches will benefit from a deeper understanding of nectin-4 biology in both health and disease, as well as a detailed exploration of the mechanisms underlying therapeutic activity and resistance.

Nectin Cell Adhesion Molecule 4 (NECTIN4) Expression in Cutaneous Squamous Cell Carcinoma: A New Therapeutic Target?

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer, and its incidence is rising because of the aging population. Nectin cell adhesion molecule 4 (NECTIN4) is involved in the progression of tumors and has attracted interest as a potential therapeutic target. However, little is known about the expression and significance of NECTIN4 in cSCC. The aim of this study was to determine the expression and function of NECTIN4 in cSCC. Immunohistological NECTIN4 expression was investigated in tissues from 34 cSCC patients. Using an A431 human SCC cell line, the role of NECTIN4 in the regulation of cell–cell attachment and migration and proliferation was assessed. NECTIN4 was expressed in most cSCC tissues and on the plasma membrane of A431 cells. Silencing of NECTIN4 prevented cell–cell attachment and induced the expression migration-related molecules, leading to an increase in cell migration. Knockdown of NECTIN4 downregulated extracellular signal-regulated kinase signaling, decreased cyclin D1 expression, and inhibited cell proliferation. These results show that NECTIN4 is expressed in cSCC and functions in the regulation of cell–cell interactions, as well as in the migration and proliferation of SCC cells. NECTIN4-targeted therapy may serve as a novel and promising treatment for cSCC.

The NEAT1_2/miR-491 Axis Modulates Papillary Thyroid Cancer Invasion and Metastasis Through TGM2/NFκb/FN1 Signaling

NEAT1 (nuclear paraspeckle assembly transcript 1) is an oncogenic long non-coding RNA (lncRNA) that facilitates tumorigenesis in multiple cancers. In papillary thyroid cancer (PTC), the molecular mechanism by which NEAT1 affects invasion and metastasis remains elusive. RNA sequencing was used to discover differentially expressed NEAT1_2 downstream genes. Protein and RNA expression analyses and immunohistochemistry detected the expression of NEAT1_2, Transglutaminase 2 (TGM2), and microRNA-491 (miR-491) among PTC and non-cancerous tissues. Transwell and wound healing assays, and a mouse model of lung metastasis were used for further functional analyses. Bioinformatics was performed to predict miRNAs binding to both NEAT1_2 and TGM2. Rescue experiments and dual-luciferase reporter assays were performed. In PTC tissues, NEAT1_2 expression was markedly increased and regulated TGM2 expression. TGM2 was overexpressed in PTC, correlating positively with exthyroidal extension and lymph node metastasis. TGM2 knockdown significantly inhibited invasion and metastasis. NEAT1_2 sponged miR-491, acting as a competing endogenous RNA to regulate TGM2 expression. Fibronectin 1 (FN1) was predicted as a TGM2 target. TGM2 could transcriptionally activate FN1 by promoting nuclear factor kappa B (NFκb) p65 nuclear translocation, ultimately promoting PTC invasion/metastasis. These findings identify that NEAT1_2 sponges miR-491 to regulate TGM2 expression. TGM2 activates FN1 via NFκb to promote PTC invasion and metastasis.

Cadherin-mediated host-pathogen interactions

Cell adhesion molecules mediate cell-to-cell and cell-to-matrix adhesions and play an immense role in a myriad of physiological processes during the growth and development of a multicellular organism. Cadherins belong to a major group of membrane-bound cell surface proteins that, in coordination with nectins, drive the formation and maintenance of adherens junctions for mediating cell to cell adhesion, cellular communication and signalling. Alongside adhesive function, the involvement of cadherins in mediating host-pathogen interactions has been extensively explored in recent years. In this review, we provide an in-depth understanding of microbial pathogens and their virulence factors that exploit cadherins for their strategical invasion into the host cell. Furthermore, macromolecular interactions involving cadherins and various microbial factors such as secretory toxins and adhesins lead to the disintegration of host cell junctions followed by the entry of the pathogen or triggering downstream signalling pathways responsible for successful invasion of the pathogenic microbes are discussed. Besides providing a comprehensive insight into some of the structural complexes involving cadherins and microbial factors to offer the mechanistic details of host-pathogen interactions, the current review also highlights novel constituents of various cell signalling events such as endocytosis machinery elicited upon microbial infections.

Phosphodiesterase-5a Knock-out Suppresses Inflammation by Down-Regulating Adhesion Molecules in Cardiac Rupture Following Myocardial Infarction

Cardiac rupture is a fatal complication of acute myocardial infarction (MI), associated with increased inflammation and damaged extracellular matrix. C57BL/6 J wild type (WT) and Pde5a knockout (Pde5a^-/-) mice were selected to establish MI model. The rupture rate of Pde5a^-/- mice was significantly reduced (P < 0.01) within 7 days post MI. The cardiac function of Pde5a^-/- mice was better than WT mice both at day 3 and 7 post MI. Immunohistochemical staining and flow cytometry showed neutrophils and macrophages were decreased in Pde5a^-/- mouse hearts. Inflammatory factors expression such as IL-1β, IL-6, IL-8, Mcp-1, TNF-α significantly decreased in Pde5a^-/- mice post MI. Moreover, western blot showed the inhibition of inflammatory response was accompanied by down-regulation of intercellular adhesion molecule-1(ICAM-1) and vascular cell adhesion molecule-1(VCAM-1) in Pde5a^-/- mice. Knockout of Pde5a reduced inflammatory cells infiltration by down-regulating the expression of ICAM-1 and VCAM-1, and prevented early cardiac rupture after MI. All authors declare that they have no conflicts of interest. This article does not contain any studies with human participants performed by any of the authors. All applicable international, national, and institutional guidelines for the care and use of animals were followed.

NECTIN4: A Novel Therapeutic Target for Melanoma

Malignant melanoma is the most common lethal skin cancer and causes death in a short time when metastasized. Although BRAF inhibitors (BRAFi) have greatly improved the prognosis of BRAF-mutated melanoma, drug resistance is a major concern even when they are combined with MEK inhibitors. Alternative treatments for BRAFi-resistant melanoma are highly anticipated. Nectin cell adhesion molecule 4 (NECTIN4) is highly expressed and associated with progression in tumors. We aimed to investigate the role of NECTIN4 in melanoma and its potency as a therapeutic target using 126 melanoma samples and BRAFi-resistant cells. Immunohistochemically, most of the clinical samples expressed NECTIN4, at least in part. NECTIN4 was highly expressed in BRAF-mutated melanoma and its high expression was associated with disease-free survival. In BRAFi-resistant melanoma cells, NECTIN4 and the PI3K/Akt pathway were upregulated, along with the acquisition of BRAFi resistance. Monomethyl auristatin E, a cytotoxic part of NECTIN4-targeted antibody-drug conjugate, was effective for BRAF-mutated or BRAFi-resistant melanoma cells. NECTIN4 inhibition increased the sensitivity of BRAFi-resistant cells to BRAFi and induced apoptosis. In conclusion, we revealed the expression and roles of NECTIN4 in melanoma. Targeted therapies against NECTIN4 can be a novel treatment strategy for melanoma, even after the acquisition of BRAFi resistance.

Enfortumab Vedotin in urothelial cancer

The treatment landscape for metastatic urothelial cancer (mUC) beyond first-line platinum-based chemotherapy has changed significantly over the last 5 years with the recent approvals of the immune checkpoint inhibitors (ICIs), fibroblast growth factor receptor (FGFR) inhibitors and most recently Enfortumab Vedotin (EV). EV is a novel antibody–drug conjugate (ADC), that delivers monomethyl auristatin E (MMAE), a microtubule-disrupting agent, inside cells harboring the cell surface nectin-4 receptor. In mUC, EV has shown encouraging response rates and received accelerated approval from the Food and Drug Administration (FDA) in December 2019 in the post-platinum and ICI setting. EV is generally well tolerated, with the main toxicities being neuropathy, skin rash, alopecia and fatigue. Notably EV can also be administered to patients with renal dysfunction, which is commonly a concern in this patient population. EV is now being tested in combination strategies and in earlier disease settings in urothelial cancers. In this review, we will discuss its mechanism of action, clinical trials leading to FDA approval as well as ongoing trials and future directions.

Prospects for Using Expression Patterns of Paramyxovirus Receptors as Biomarkers for Oncolytic Virotherapy

Simple Summary

Some non-pathogenic viruses that do not cause serious illness in humans can efficiently target and kill cancer cells and may be considered candidates for cancer treatment with virotherapy. However, many cancer cells are protected from viruses. An important goal of personalized cancer treatment is to identify viruses that can kill a certain type of cancer cells. To this end, researchers investigate expression patterns of cell entry receptors, which viruses use to bind to and enter host cells. We summarized and analyzed the receptor expression patterns of two paramyxoviruses: The non-pathogenic measles and the Sendai viruses. The receptors for these viruses are different and can be proteins or lipids with attached carbohydrates. This review discusses the prospects for using these paramyxovirus receptors as biomarkers for successful personalized virotherapy for certain types of cancer.

Abstract

The effectiveness of oncolytic virotherapy in cancer treatment depends on several factors, including successful virus delivery to the tumor, ability of the virus to enter the target malignant cell, virus replication, and the release of progeny virions from infected cells. The multi-stage process is influenced by the efficiency with which the virus enters host cells via specific receptors. This review describes natural and artificial receptors for two oncolytic paramyxoviruses, nonpathogenic measles, and Sendai viruses. Cell entry receptors are proteins for measles virus (MV) and sialylated glycans (sialylated glycoproteins or glycolipids/gangliosides) for Sendai virus (SeV). Accumulated published data reviewed here show different levels of expression of cell surface receptors for both viruses in different malignancies. Patients whose tumor cells have low or no expression of receptors for a specific oncolytic virus cannot be successfully treated with the virus. Recent published studies have revealed that an expression signature for immune genes is another important factor that determines the vulnerability of tumor cells to viral infection. In the future, a combination of expression signatures of immune and receptor genes could be used to find a set of oncolytic viruses that are more effective for specific malignancies.

An evolutionarily conserved charged residue dictates the specificity of heterophilic interactions among nectins

Nectins are a family of four cell surface glycoproteins belonging to the immunoglobulin superfamily that mediate cell-cell adhesion and associated signalling pathways, thereby regulating several physiological processes including morphogenesis, growth and development of multicellular organisms. Nectins interact among themselves through their extracellular domains from the adjacent cells in both homophilic and heterophilic fashions to support cell-cell adhesion. Although nectins form homodimers as demonstrated in experimental set-ups, only the specific heterophilic interactions among nectins are physiologically relevant as shown by in vivo studies. It has been hypothesised that a conserved charged residue present at the binding interface acts as the molecular switch for heterophilic nectin-nectin recognitions. In this work, we have analysed the energetics of homophilic and heterophilic interactions of nectins, followed by surface plasmon resonance-based binding studies and complementary in silico analyses. Our findings confirm that the conserved charged residues at the binding interfaces dictate the specificity of the nectin-nectin heterophilic interactions. Furthermore, these residues also play a role in conferring higher affinity to the heterophilic interactions, thereby making them physiologically more prevalent compared to homophilic interactions. Thus, this work reveals the molecular basis of heterophilic recognitions among nectins that contribute to their physiological functions.

Genome-Wide DNA Methylation Analysis of Mammary Gland Tissues From Chinese Holstein Cows With Staphylococcus aureus Induced Mastitis

Staphylococcus aureus intramammary infection is one of the most common causes of chronic mastitis in dairy cows, whose development may be associated with epigenetic changes in the expression of important host defense genes. This study aimed to construct a genome-wide DNA methylation profile of the mammary gland of Chinese Holstein cows (n = 3) following experimentally induced S. aureus mastitis, and to explore the potential gene regulatory mechanisms affected by DNA methylation during S. aureus mastitis. DNA was extracted from S. aureus-positive (n = 3) and S. aureus-negative (n = 3) mammary gland quarters and subjected to methylation-dependent restriction-site associated DNA sequencing (Methyl-RAD Seq). Results showed that CmCGG/CmCWGG DNA methylation sites were unevenly distributed and concentrated on chromosomes 5, 11, and 19, and within intergenic regions and intron regions of genes. Compared with healthy control quarters, 9,181 significantly differentially methylated (DM) CmCGG sites and 1,790 DM CmCWGG sites were found in the S. aureus-positive quarters (P < 0.05, |log2FC| > 1). Furthermore, 363 CmCGG differently methylated genes (DMGs) and 301 CmCWGG DMGs (adjusted P < 0.05, |log2FC| > 1) were identified. Gene ontology and KEGG enrichment analysis indicated that CmCGG DMGs are involved in immune response pathways, while the CmCWGG DMGs were mainly enriched in gene ontology terms related to metabolism. The mRNAs of 526 differentially methylated CmCGG genes and 124 differentially methylated CmCWGG genes were also significantly differentially expressed (RNA-Seq data) in the same samples, herein denoted differentially methylated and expressed genes (DMEGs) (P < 0.05). Functional enrichment analysis of DMEGs revealed roles related to biological processes, especially the regulation of immune response to diseases. CmCGG DMEGs like IL6R, TNF, BTK, IL1R2, and TNFSF8 enriched in several immune-related GO terms and pathways indicated their important roles in host immune response and their potential as candidate genes for S. aureus mastitis. These results suggest potential regulatory roles for DNA methylation in bovine mammary gland processes during S. aureus mastitis and serves as a reference for future epigenetic regulation and mechanistic studies.

Enfortumab Vedotin-ejfv: A First-in-Class Anti-Nectin-4 Antibody-Drug Conjugate for the Management of Urothelial Carcinoma

OBJECTIVE

To evaluate the pharmacology, pharmacokinetics, clinical efficacy, safety, dosing, cost, and clinical implications of enfortumab vedotin-ejfv (EV) in the treatment of locally advanced or metastatic urothelial carcinoma (UC).

DATA SOURCES

A literature search of PubMed (inception to August 2020) was conducted using the terms enfortumab, vedotin, Padcev, and Nectin. Data were also obtained from package inserts, meeting abstracts, and ongoing studies from ClinicalTrials.gov.

STUDY SELECTION AND DATA EXTRACTION

All relevant published articles, package inserts, and meeting abstracts evaluating EV for the treatment of UC were analyzed.

DATA SYNTHESIS

Antibody-drug conjugates (ADCs) deliver potent cytotoxic agents using highly selective monoclonal antibodies. Targeting the near-universal expression of Nectin-4 on UC cells is a viable therapeutic strategy. In a pivotal phase II trial, EV demonstrated an overall response rate of 44%, and a median duration of response of 7.6 months. Estimated overall survival was 11.7 months with a median estimated progression-free survival of 5.6 months. Results were similar among difficult-to-treat patients, including those with liver metastases. Unique toxicity concerns with EV require careful consideration and monitoring.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

EV, a first-in-class anti-Nectin-4 ADC, provides impressive response rates with manageable toxicities, making it a promising treatment option for patients with multiply relapsed or refractory UC.

CONCLUSION

The US Food and Drug Administration-approved EV demonstrates antitumor activity in heavily pretreated patients with UC but harbors important adverse effects and financial concerns. Additional studies are required to identify the optimal sequencing, patient population, and place in therapy for EV.

Antibody-drug conjugates for the treatment of urothelial carcinoma

INTRODUCTION

The therapeutic landscape for urothelial carcinoma has changed significantly over the past few years with the addition of immunotherapy to platinum-based chemotherapy. Targeted therapy against FGFR (fibroblast growth factor receptor) is now also approved for the minority of patients with FGFR aberrations. Antibody-drug conjugates (ADCs) are of great interest in urothelial carcinoma, with a recent FDA approval for enfortumab vedotin (EV) and others in development.

AREAS COVERED

This review will provide an overview of treatment of advanced urothelial carcinoma and detail the various ADCs being studied in this disease.

EXPERT OPINION

ADCs are an important therapeutic option for urothelial carcinoma. Responses to EV exceeded 40% in heavily pre-treated patients, while the response rate to EV combined with pembrolizumab in a phase 1b trial was ~70% in treatment-naïve patients. EV has already been approved in the United States and we await randomized data to confirm a survival benefit with EV. Meanwhile, studies of other ADCs, including in biomarker-selected populations, are ongoing. ADCs will undoubtedly play an increasing role in the management of urothelial carcinoma and will likely be offered earlier in the disease course, resulting in significant changes to treatment algorithms in urothelial cancer in the coming years.

Selectins-The Two Dr. Jekyll and Mr. Hyde Faces of Adhesion Molecules-A Review

Selectins belong to a group of adhesion molecules that fulfill an essential role in immune and inflammatory responses and tissue healing. Selectins are glycoproteins that decode the information carried by glycan structures, and non-covalent interactions of selectins with these glycan structures mediate biological processes. The sialylated and fucosylated tetrasaccharide sLe^x is an essential glycan recognized by selectins. Several glycosyltransferases are responsible for the biosynthesis of the sLe^x tetrasaccharide. Selectins are involved in a sequence of interactions of circulated leukocytes with endothelial cells in the blood called the adhesion cascade. Recently, it has become evident that cancer cells utilize a similar adhesion cascade to promote metastases. However, like Dr. Jekyll and Mr. Hyde’s two faces, selectins also contribute to tissue destruction during some infections and inflammatory diseases. The most prominent function of selectins is associated with the initial stage of the leukocyte adhesion cascade, in which selectin binding enables tethering and rolling. The first adhesive event occurs through specific non-covalent interactions between selectins and their ligands, with glycans functioning as an interface between leukocytes or cancer cells and the endothelium. Targeting these interactions remains a principal strategy aimed at developing new therapies for the treatment of immune and inflammatory disorders and cancer. In this review, we will survey the significant contributions to and the current status of the understanding of the structure of selectins and the role of selectins in various biological processes. The potential of selectins and their ligands as therapeutic targets in chronic and acute inflammatory diseases and cancer will also be discussed. We will emphasize the structural characteristic of selectins and the catalytic mechanisms of glycosyltransferases involved in the biosynthesis of glycan recognition determinants. Furthermore, recent achievements in the synthesis of selectin inhibitors will be reviewed with a focus on the various strategies used for the development of glycosyltransferase inhibitors, including substrate analog inhibitors and transition state analog inhibitors, which are based on knowledge of the catalytic mechanism.

Tracing the evolution of nectin and nectin-like cell adhesion molecules

Nectin and nectin-like cell adhesion molecules (collectively referred as nectin family henceforth) are known to mediate cell-cell adhesion and related functions. While current literature suggests that nectins are prevalent in vertebrates, there are no in-depth analyses regarding the evolution of nectin family as a whole. In this work, we examine the evolutionary origin of the nectin family, using selected multicellular metazoans representing diverse clades whose whole genome sequencing data is available. Our results show that this family may have appeared earlier during metazoan evolution than previously believed. Systematic analyses indicate the order in which various members of nectin family seem to have evolved, with some nectin-like molecules appearing first, followed by the evolution of other members. Furthermore, we also found a few possible ancient homologues of nectins. While our study confirms the previous grouping of the nectin family into nectins and nectin-like molecules, it also shows poliovirus receptor (PVR/nectin-like-5) to possess characteristics that are intermediate between these two groups. Interestingly, except for PVR, the other nectins show surprising sequence conservations across species, suggesting evolutionary constraints due to critical roles played by these proteins.

Crystal structure of bovine herpesvirus 1 glycoprotein D bound to nectin-1 reveals the basis for its low-affinity binding to the receptor

Bovine herpesvirus 1 (BHV-1) has received increasing attention for its potential oncolytic applications. BHV-1 recognizes nectin-1 for cell entry via viral glycoprotein D (gD) but represents a low-affinity nectin-1 binding virus. The molecular basis underlying this low receptor-binding affinity, however, remains unknown. Here, the crystal structures of BHV-1 gD in the free and nectin-1-bound forms are presented. While showing an overall resembled nectin-1 binding mode to other alphaherpesvirus gDs, BHV-1 gD has a unique G-strand/α2-helix interloop that disturbs gD/nectin-1 interactions. Residue R188 residing in this loop is observed to otherwise cause strong steric hindrance with the bound receptor, making a large conformational change of the loop a prerequisite for nectin-1 engagement. Subsequently, substitution of R188 with glycine markedly enhances the affinity of the BHV-1-gD/nectin-1 interaction (by about fivefold). These structural and functional data delineate the receptor-recognition basis for BHV-1, which might facilitate BHV-1-based oncolytic design in the future.

EV-101: A Phase I Study of Single-Agent Enfortumab Vedotin in Patients With Nectin-4-Positive Solid Tumors, Including Metastatic Urothelial Carcinoma

PURPOSE

To assess the safety/tolerability and antitumor activity of enfortumab vedotin (EV), a novel investigational antibody-drug conjugate that delivers the microtubule-disrupting agent, monomethyl auristatin E, to cells that express Nectin-4.

METHODS

EV-101 is a phase I dose escalation/expansion study that enrolled patients with Nectin-4-expressing solid tumors (eg, metastatic urothelial carcinoma [mUC]) who progressed on ≥ 1 prior chemotherapy regimen and/or programmed death-1 receptor/programmed death ligand-1 [PD-(L)1] inhibitor, including a cohort of patients with mUC who received prior anti-PD-(L)1 therapy. Patients received escalating doses of EV up to 1.25 mg/kg on days 1, 8, and 15 of every 28-day cycle. Primary objectives were evaluation of safety/tolerability and pharmacokinetics; antitumor activity was a secondary objective.

RESULTS

Enrolled patients with mUC (n = 155) were heavily pretreated, with 96% having prior platinum-based chemotherapy and 29% receiving ≥ 3 lines of prior treatment. Maximum tolerated dose of EV was not established; however, the recommended phase II dose was identified as 1.25 mg/kg. Rash, peripheral neuropathy, fatigue, alopecia, and nausea were the most common treatment-related adverse events (TRAEs); the most common TRAEs were grade 1-2 in severity. Among the 112 patients with mUC treated with single-agent EV 1.25 mg/kg, the investigator-assessed confirmed objective response rate (ORR) was 43%, and duration of response was 7.4 months. Median overall survival (OS) was 12.3 months, and the OS rate at 1 year was 51.8%. Similar ORR and estimated median OS were observed in patients ≥ 75 years of age with and without prior anti-PD-(L)1 treatment, liver metastases, or upper-tract disease.

CONCLUSION

Single-agent EV was generally well tolerated and provided clinically meaningful and durable responses in patients with mUC; survival data are encouraging. A pivotal phase II and a confirmatory phase III study are ongoing.

Relationship between apical junction proteins, gene expression and cancer

The apical junctional complex (AJC) is a cell-cell adhesion system present at the upper portion of the lateral membrane of epithelial cells integrated by the tight junction (TJ) and the adherens junction (AJ). This complex is crucial to initiate and stabilize cell-cell adhesion, to regulate the paracellular transit of ions and molecules and to maintain cell polarity. Moreover, we now consider the AJC as a hub of signal transduction that regulates cell-cell adhesion, gene transcription and cell proliferation and differentiation. The molecular components of the AJC are multiple and diverse and depending on the cellular context some of the proteins in this complex act as tumor suppressors or as promoters of cell transformation, migration and metastasis outgrowth. Here, we describe these new roles played by TJ and AJ proteins and their potential use in cancer diagnostics and as targets for therapeutic intervention.

From Bound Cells Comes a Sound Mind: The Role of Neuronal Growth Regulator 1 in Psychiatric Disorders

Cell-to-cell adhesion is important for maintenance of brain structure and function. Abnormal neuronal cell adhesion and loss of its connectivity are considered a main cause of psychiatric disorders such as major depressive disorder (MDD). Various cell adhesion molecules (CAMs) are involved in neuronal cell adhesions and thereby affect brain functions such as learning and memory, cognitive functions, and psychiatric functions. Compared with other CAMs, neuronal growth regulator 1 (Negr1) has a distinct functioning mechanism in terms of its cross-talk with cytokine receptor signaling. Negr1 is a member of the immunoglobulin LON (IgLON) family of proteins and is involved in neuronal outgrowth, dendritic arborization, and synapse formation. In humans, Negr1 is a risk gene for obesity based on a genome-wide association study. More recently, accumulating evidence supports that it also plays a critical role in psychiatric disorders. In this review, we discuss the recent findings on the role of Negr1 in MDD, focusing on its regulatory mechanism. We also provide evidence of putative involvement of Negr1 in other psychiatric disorders based on the novel behavioral phenotypes of Negr1 knockout mice.

Fibroblast growth factor receptor-like-1: a new therapeutic target and unfavorable prognostic indicator for rectal adenocarcinoma

Fibroblast growth factor receptor-like-1 (FGFRL1) is important to cell motility and links with tumorigenic potential in various types of cancers. To investigate the biological function and underlying mechanism of FGFRL1 in rectal adenocarcinoma, we conducted this study. TCGA and Oncomine databases were used to analyze FGFRL1 expression and its association with clinical characteristics or overall survival (OS) in rectal adenocarcinoma patients. siRNA strategy was implemented to knockdown FGFRL1 expression in rectal adenocarcinoma cells. CCK8, colony formation, wound healing, and transwell assays were implemented to measure cell behaviors. qRT-PCR and western blot were utilized to identify mRNA and protein expression levels. FGFRL1 was significantly increased in rectal adenocarcinoma tissue samples, either colon or rectum. High-regulation of FGFRL1 expression induced poorer outcome of rectal adenocarcinoma patients. Downregulation of FGFRL1 inhibited the proliferation, colony formation, migration, and invasion of SW837 cells. The MAPK pathway-related proteins, phosphorylation of MEK and ERK, were also decreased after si-FGFRL1 transfection. These findings demonstrated that FGFRL1, acting as a potential inducator, may promote the progression of rectal adenocarcinoma via activating the MAPK signaling pathway.

Alpha-hemolysin of uropathogenic Escherichia coli induces GM-CSF-mediated acute kidney injury

Uropathogenic Escherichia coli (UPEC) is the leading cause of urinary tract infections (UTIs), inducing acute pyelonephritis and may result in permanent renal scarring and failure. Alpha-hemolysin (HlyA), a key UPEC toxin, causes serious tissue damage; however, the mechanism through which HlyA induces kidney injury remains unclear. In the present study, granulocyte-macrophage colony-stimulating factor (GM-CSF) secreted by renal epithelial cells was upregulated by HlyA in vitro and in vivo, which induced M1 macrophage accumulation in kidney, and ADAM10 was found involved in HlyA-induced GM-CSF. Macrophage elimination or GM-CSF neutralization protected against acute kidney injury in mice, and increased GM-CSF was detected in urine of patients infected by hlyA-positive UPEC. In addition, HlyA was found to promote UPEC invasion into renal epithelial cells by interacting with Nectin-2 in vitro. However, HlyA did not affect bacterial titers during acute kidney infections, and HlyA-induced invasion did not contribute to GM-CSF upregulation in vitro, which indicate that HlyA-induced GM-CSF is independent of bacteria invasion. The role of GM-CSF in HlyA-mediated kidney injury may lead to novel strategies to treat acute pyelonephritis.

Continuous Dynamic Modeling of Regulated Cell Adhesion: Sorting, Intercalation, and Involution

Cell-cell adhesion is essential for tissue growth and multicellular pattern formation and crucial for the cellular dynamics during embryogenesis and cancer progression. Understanding the dynamical gene regulation of cell adhesion molecules (CAMs) responsible for the emerging spatial tissue behaviors is a current challenge because of the complexity of these nonlinear interactions and feedback loops at different levels of abstraction-from genetic regulation to whole-organism shape formation. To extend our understanding of cell and tissue behaviors due to the regulation of adhesion molecules, here we present a novel, to our knowledge, model for the spatial dynamics of cellular patterning, growth, and shape formation due to the differential expression of CAMs and their regulation. Capturing the dynamic interplay between genetic regulation, CAM expression, and differential cell adhesion, the proposed continuous model can explain the complex and emergent spatial behaviors of cell populations that change their adhesion properties dynamically because of inter- and intracellular genetic regulation. This approach can demonstrate the mechanisms responsible for classical cell-sorting behaviors, cell intercalation in proliferating populations, and the involution of germ layer cells induced by a diffusing morphogen during gastrulation. The model makes predictions on the physical parameters controlling the amplitude and wavelength of a cellular intercalation interface, as well as the crucial role of N-cadherin regulation for the involution and migration of cells beyond the gradient of the morphogen Nodal during zebrafish gastrulation. Integrating the emergent spatial tissue behaviors with the regulation of genes responsible for essential cellular properties such as adhesion will pave the way toward understanding the genetic regulation of large-scale complex patterns and shapes formation in developmental, regenerative, and cancer biology.

RNA-seq transcriptome profiling of porcine lung from two pig breeds in response to Mycoplasma hyopneumoniae infection

Background

Mycoplasma hyopneumoniae (Mhp) is the main pathogen causing respiratory disease in the swine industry. Mhp infection rates differ across pig breeds, with Chinese native pig breeds that exhibit high fecundity (e.g., Jiangquhai, Meishan, Erhualian) more sensitive than Duroc, Landrace, and other imported pig breeds. However, the genetic basis of the immune response to Mhp infection in different pig breeds is largely unknown.

Aims

The aims of this study were to determine the relative Mhp susceptibility of the Chinese native Jiangquhai breed compared to the Duroc breed, and identify molecular mechanisms of differentially expressed genes (DEGs) using an RNA-sequencing (RNA-seq) approach.

Methods

Jiangquhai and Duroc pigs were artificially infected with the same Mhp dose. The entire experiment lasted 28 days. Daily weight gain, Mhp-specific antibody levels, and lung lesion scores were measured to evaluate the Mhp infection susceptibility of different breeds. Experimental pigs were slaughtered on the 28th day. Lung tissues were collected for total RNA extraction. RNA-seq was performed to identify DEGs, which were enriched by gene ontology (GO) and the Kyoto Encyclopedia annotation of Genes and Genomes (KEGG) databases. DEGs were validated with real-time quantitative polymerase chain reaction (RT-qPCR).

Results

Infection with the same Mhp dose produced a more serious condition in Jiangquhai pigs than in Duroc pigs. Jiangquhai pigs showed poorer growth, higher Mhp antibody levels, and more serious lung lesions compared with Duroc pigs. RNA-seq identified 2,250 and 3,526 DEGs in lung tissue from Jiangquhai and Duroc pigs, respectively. The two breeds shared 1,669 DEGs, which were involved in immune-relevant pathways including cytokine-cytokine receptor interaction, PI3K-Akt signaling pathway, and chemokine signaling pathway. Compared to Jiangquhai pigs, more chemokines, interferon response factors, and interleukins were specifically activated in Duroc pigs; CXCL10, CCL4, IL6 and IFNG genes were significantly up-regulated, which may help Duroc pigs enhance immune response and reduce Mhp susceptibility.

Conclusion

This study demonstrated differential immune-related DEGs in lung tissue from the two breeds, and revealed an important role of genetics in the immune response to Mhp infection. The biological functions of these important DEGs should be further confirmed and maybe applied as molecular markers that improve pig health.

A Vaccinomics Approach for the Identification of Tick Protective Antigens for the Control of Ixodes ricinus and Dermacentor reticulatus Infestations in Companion Animals

Ticks and tick-borne pathogens affect health and welfare of companion animals worldwide, and some human tick-borne diseases are associated with exposure to domestic animals. Vaccines are the most environmentally friendly alternative to acaracides for the control of tick infestations, and to reduce the risk for tick-borne diseases affecting human and animal health. However, vaccines have not been developed or successfully implemented for most vector-borne diseases. The main limitation for the development of effective vaccines is the identification of protective antigens. To address this limitation, in this study we used an experimental approach combining vaccinomics based on transcriptomics and proteomics data with vaccination trials for the identification of tick protective antigens. The study was focused on Ixodes ricinus and Dermacentor reticulatus that infest humans, companion animals and other domestic and wild animals, and transmit disease-causing pathogens. Tick larvae and adult salivary glands were selected for analysis to target tick organs and developmental stages playing a key role during tick life cycle and pathogen infection and transmission. Two I. ricinus (heme lipoprotein and uncharacterized secreted protein) and five D. reticulatus (glypican-like protein, secreted protein involved in homophilic cell adhesion, sulfate/anion exchanger, signal peptidase complex subunit 3, and uncharacterized secreted protein) proteins were identified as the most effective protective antigens based on the criteria of vaccine E > 80%. The putative function of selected protective antigens, which are involved in different biological processes, resulted in vaccines affecting multiple tick developmental stages. These results suggested that the combination of some of these antigens might be considered to increase vaccine efficacy through antigen synergy for the control of tick infestations and potentially affecting pathogen infection and transmission. These antigens were proposed for commercial vaccine development for the control of tick infestations in companion animals, and potentially in other hosts for these tick species.

Cell Adhesion Molecules and Their Roles and Regulation in the Immune and Tumor Microenvironment

The immune system and cancer have a complex relationship with the immune system playing a dual role in tumor development. The effector cells of the immune system can recognize and kill malignant cells while immune system-mediated inflammation can also promote tumor growth and regulatory cells suppress the anti-tumor responses. In the center of all anti-tumor responses is the ability of the immune cells to migrate to the tumor site and to interact with each other and with the malignant cells. Cell adhesion molecules including receptors of the immunoglobulin superfamily and integrins are of crucial importance in mediating these processes. Particularly integrins play a vital role in regulating all aspects of immune cell function including immune cell trafficking into tissues, effector cell activation and proliferation and the formation of the immunological synapse between immune cells or between immune cell and the target cell both during homeostasis and during inflammation and cancer. In this review we discuss the molecular mechanisms regulating integrin function and the role of integrins and other cell adhesion molecules in immune responses and in the tumor microenvironment. We also describe how malignant cells can utilize cell adhesion molecules to promote tumor growth and metastases and how these molecules could be targeted in cancer immunotherapy.

Family of neural wiring receptors in bilaterians defined by phylogenetic, biochemical, and structural evidence

The evolution of complex nervous systems was accompanied by the expansion of numerous protein families, including cell-adhesion molecules, surface receptors, and their ligands. These proteins mediate axonal guidance, synapse targeting, and other neuronal wiring-related functions. Recently, 32 interacting cell surface proteins belonging to two newly defined families of the Ig superfamily (IgSF) in fruit flies were discovered to label different subsets of neurons in the brain and ventral nerve cord. They have been shown to be involved in synaptic targeting and morphogenesis, retrograde signaling, and neuronal survival. Here, we show that these proteins, Dprs and DIPs, are members of a widely distributed family of two- and three-Ig domain molecules with neuronal wiring functions, which we refer to as Wirins. Beginning from a single ancestral Wirin gene in the last common ancestor of Bilateria, numerous gene duplications produced the heterophilic Dprs and DIPs in protostomes, along with two other subfamilies that diversified independently across protostome phyla. In deuterostomes, the ancestral Wirin evolved into the IgLON subfamily of neuronal receptors. We show that IgLONs interact with each other and that their complexes can be broken by mutations designed using homology models based on Dpr and DIP structures. The nematode orthologs ZIG-8 and RIG-5 also form heterophilic and homophilic complexes, and crystal structures reveal numerous apparently ancestral features shared with Dpr-DIP complexes. The evolutionary, biochemical, and structural relationships we demonstrate here provide insights into neural development and the rise of the metazoan nervous system.

Targeting advanced urothelial carcinoma-developing strategies

PURPOSE OF REVIEW

Advanced urothelial carcinoma is a heterogeneous disease with high burden of morbidity, mortality, and cost. Significant progress has been made in understanding the biology of the disease and the development of immunotherapies and targeted therapies. In this review, we summarize the current and future therapeutic approaches in the management of urothelial carcinoma.

RECENT FINDINGS

Advances in immune checkpoint inhibitors resulted in the Food and Drug Administration (FDA) approvals of atezolizumab in 2016, and pembrolizumab, avelumab, durvalumab, and nivolumab in 2017 for the treatment of advanced urothelial carcinoma. More recently, development of inhibitors targeting the fibroblast growth factor receptor genetic alterations and antibody-drug conjugates targeting specific cell surface antigens (trop2, nectin4, and SLITRK6) resulted in several FDA breakthrough designations for urothelial carcinoma.

CONCLUSION

The development of novel therapies targeting the immune and molecular pathways of advanced urothelial carcinoma is promising for the improvement of outcomes in this lethal disease. Ongoing efforts are poised to optimize therapeutic options in the post-chemotherapy arena. In the era of precision medicine, the future of urothelial carcinoma lies in using less cytotoxic chemotherapy, more targeted therapy and immunotherapy, and possibly a combination of these therapeutic approaches.

Over-expression of Nectin-4 promotes progression of esophageal cancer and correlates with poor prognosis of the patients

Background

Nectin-4, also known as PVRL4 (poliovirus-receptor-like 4), is specifically expressed in the embryo and placenta. Recent studies have reported that the Nectin-4 is over-expressed in multiple human cancers, and such abnormal expression is associated with cancer progression and poor prognosis of the patients. In the present study, we aimed to characterize the expression pattern of Nectin-4 in human esophageal cancer (EC) tissues, and to investigate its clinical implications, prognostic value and regulatory effects on cellular functions of EC cells.

Methods

In the present study, we first examined Nectin-4 expression in human EC tissues by using immunohistochemistry (IHC) assay and analyzed the clinical associations. Then the cellular studies in vitro and the nude mice tumor model in vivo were used to examine the regulatory role of Nectin-4 in the progression of EC.

Results

Our results demonstrated that over-expression of Nectin-4 in human EC tissues was significantly associated with tumor size, depth of tumor invasion, and poor prognosis of the patients. The intervention of Nectin-4 expression in EC cell lines showed that the increased Nectin-4 expression could significantly promote the cell viability, migration, invasion and tumor formation.

Conclusions

Our present data unveiled that Nectin-4 played an important role in tumor biology and could serve as a useful prognostic predictor of human EC.

The polymeric immunoglobulin receptor-like protein from Marsupenaeus japonicus is a receptor for white spot syndrome virus infection

Viral entry into the host cell is the first step towards successful infection. Viral entry starts with virion attachment, and binding to receptors. Receptor binding viruses either directly release their genome into the cell, or enter cells through endocytosis. For DNA viruses and a few RNA viruses, the endocytosed viruses will transport from cytoplasm into the nucleus followed by gene expression. Receptors on the cell membrane play a crucial role in viral infection. Although several attachment factors, or candidate receptors, for the infection of white spot syndrome virus (WSSV) were identified in shrimp, the authentic entry receptors for WSSV infection and the intracellular signaling triggering by interaction of WSSV with receptors remain unclear. In the present study, a receptor for WSSV infection in kuruma shrimp, Marsupenaeus japonicus, was identified. It is a member of the immunoglobulin superfamily (IgSF) with a transmembrane region, and is similar to the vertebrate polymeric immunoglobulin receptor (pIgR); therefore, it was designated as a pIgR-like protein (MjpIgR for short). MjpIgR was detected in all tissues tested, and its expression was significantly induced by WSSV infection at the mRNA and protein levels. Knockdown of MjpIgR, and blocking MjpIgR with its antibody inhibited WSSV infection in shrimp and overexpression of MjpIgR facilitated the invasion of WSSV. Further analyses indicated that MjpIgR could independently render non-permissive cells susceptible to WSSV infection. The extracellular domain of MjpIgR interacts with envelope protein VP24 of WSSV and the intracellular domain interacts with calmodulin (MjCaM). MjpIgR was oligomerized and internalized following WSSV infection and the internalization was associated with endocytosis of WSSV. The viral internalization facilitating ability of MjpIgR could be blocked using chlorpromazine, an inhibitor of clathrin dependent endocytosis. Knockdown of Mjclathrin and its adaptor protein AP-2 also inhibited WSSV internalization. All the results indicated that MjpIgR-mediated WSSV endocytosis was clathrin dependent. The results suggested that MjpIgR is a WSSV receptor, and that WSSV enters shrimp cells via the pIgR-CaM-Clathrin endocytosis pathway.

White Spot Syndrome Virus (WSSV) is one of the most virulent pathogens in shrimp farming. Several viral candidate receptors, or attachment factors were reported in previous studies, however, most of them are not authentic transmembrane proteins. In particular, the protein receptor(s) required the intracellular signaling triggering by interaction of WSSV with receptors remain unclear. In the present study, a polymeric immunoglobulin receptor (pIgR) like protein, a bona fide transmembrane receptor, was identified in kuruma shrimp, Marsupenaeus japonicus (MjpIgR for short). Knockdown of MjpIgR by RNA interference, and blocking it by its antibody prevented WSSV infection in shrimp and overexpression of MjpIgR facilitated the invasion of WSSV. Further study found that MjpIgR could independently render non-permissive cells susceptible to WSSV infection. The extracellular cellular domain of MjpIgR interacts with envelope protein VP24 of WSSV and the intracellular domain interacts with calmodulin (MjCaM). MjpIgR was oligomerized and internalized following WSSV infection and the internalization was associated with endocytosis of WSSV. The viral internalization facilitating ability of MjpIgR could be blocked using chlorpromazine, an inhibitor of clathrin dependent endocytosis, indicating that MjpIgR-mediated WSSV endocytosis was clathrin dependent. The results suggested that MjpIgR is a WSSV receptor, and that WSSV enters shrimp cells via the pIgR-CaM-Clathrin endocytosis pathway. This study provides a new target for WSSV control in shrimp aquaculture.

Expression and (Lacking) Internalization of the Cell Surface Receptors of Clostridioides difficile Toxin B

Toxin-producing strains of Clostridioides difficile and Clostridium perfringens cause infections of the gastrointestinal tract in humans and ruminants, with the toxins being major virulence factors, essential for the infection, and responsible for the onset of severe symptoms. C. difficile toxin A (TcdA) and toxin B (TcdB), and the large cytotoxin (TpeL) from C. perfringens are single chain bacterial protein toxins with an AB-like toxin structure. The C-terminal delivery domain mediates cell entry of the N-terminal glycosyltransferase domain by receptor-mediated endocytosis. Several cell surface proteins have been proposed to serve as toxin receptors, including chondroitin-sulfate proteoglycan 4 (CSPG4), poliovirus receptor-like 3 (PVRL3), and frizzled-1/2/7 (FZD1/2/7) for TcdB and LDL-receptor-related protein-1 (LRP1) for TpeL. The expression of the TcdB receptors was investigated in human intestinal organoids (HIOs) and in cultured cell lines. HIOs from four human donors exhibited a comparable profile of receptor expression, with PVRL3, LRP1, and FZD7 being expressed and CSPG4 and FZD2 not being expressed. In human epithelial Caco-2 cells and HT29 cells as well as in immortalized murine fibroblasts, either receptor FZD2/7, CSPG4, PVRL3, and LRP1 was expressed. The question whether the toxins take advantage of the normal turnover of their receptors (i.e., constitutive endocytosis and recycling) from the cell surface or whether the toxins activity induce the internalization of their receptors has not yet been addressed. For the analysis of receptor internalization, temperature-induced uptake of biotinylated toxin receptors into immortalized mouse embryonic fibroblasts (MEFs) and Caco-2 cells was exploited. Solely LRP1 exhibited constitutive endocytosis from the plasma membrane to the endosome, which might be abused by TpeL (and possibly TcdB as well) for cell entry. Furthermore, internalization of CSPG4, PVRL3, FZD2, and FZD7 was observed neither in MEFs nor in Caco-2 cells. FZD2/7, CSPG4, and PVRL3 did thus exhibit no constitutive recycling. The presence of TcdB and the p38 activation induced by anisomycin were not able to induce or enhance CSPG4 or PVRL3 uptake in MEFs. In conclusion, FZD2/7, CSPG4, and PVRL3 seem to serve as cell surface binding receptors rather than internalizing receptors of TcdB.

microRNA-4516 Contributes to Different Functions of Epithelial Permeability Barrier by Targeting Poliovirus Receptor Related Protein 1 in Enterovirus 71 and Coxsackievirus A16 Infections

Enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16) remain the predominant etiological agents of hand, foot, and mouth disease (HFMD). The clinical manifestations caused by the two viruses are obviously different. CV-A16 usually triggers a repeated infection, and airway epithelial integrity is often the potential causative factor of respiratory repeated infections. Our previous studies have demonstrated that there were some differentially expressed miRNAs involved in the regulation of adhesion function of epithelial barrier in EV-A71 and CV-A16 infections. In this study, we compared the differences between EV-A71 and CV-A16 infections on the airway epithelial barrier function in human bronchial epithelial (16HBE) cells and further screened the key miRNA which leaded to the formation of these differences. Our results showed that more rapid proliferation, more serious destruction of 16HBE cells permeability, more apoptosis and disruption of intercellular adhesion-associated molecules were found in CV-A16 infection as compared to EV-A71 infection. Furthermore, we also identified that microRNA-4516 (miR-4516), which presented down-regulation in EV-A71 infection and up-regulation in CV-A16 infection was an important regulator of intercellular junctions by targeting Poliovirus receptor related protein 1(PVRL1). The expressions of PVRL1, claudin4, ZO-1 and E-cadherin in CV-A16-infected cells were significantly less than those in EV-A71-infected cells, while the expressions of these proteins were subverted when pre-treated with miR-4516-overexpression plasmid in EV-A71 infected and miR-4516-knockdown plasmid in CV-A16 infected 16HBE cells. Thus, these data suggested that the opposite expression of miR-4516 in EV-A71 and CV-A16 infections might be the initial steps leading to different epithelial impairments of 16HBE cells by destroying intercellular adhesion, which finally resulted in different outcomes of EV-A71 and CV-A16 infections.

High expression of Nectin-4 is associated with unfavorable prognosis in gastric cancer

Nectins are Ca²⁺-independent immunoglobulin-like cell adhesion molecules that belong to a family of four members that function in a number of biological cellular activities. Nectin-4 is overexpressed in several types of human cancer; however, the functional and prognostic significance of Nectin-4 in gastric cancer (GC) remains unclear. In the present study, the reverse transcription-quantitative polymerase chain reaction and tissue microarray immunohistochemical analysis were used to investigate the expression of Nectin-4 in GC as well as its function in the prognosis of patients with GC. The results indicated that mRNA and protein expression of Nectin-4 were increased in tumor tissues compared with the matched non-tumor tissues. Expression of Nectin-4 was closely associated with differentiation (P=0.004), primary tumor (P=0.001), lymph node metastasis (P<0.001) and tumor-node-metastasis (TNM) stage (P<0.001). Positive Nectin-4 expression (P=0.001) and advanced TNM stage (P<0.001) were demonstrated to be associated with overall survival time in multivariate analyses. These results suggest that Nectin-4 may serve a significant function in GC and may serve as a novel clinic pathological biomarker and therapeutic target in GC.

Spatiotemporal coordination of cellular differentiation and tissue morphogenesis in organ of Corti development

The organ of Corti, an acoustic sensory organ, is a specifically differentiated epithelium of the cochlear duct, which is a part of the membranous labyrinth in the inner ear. Cells in the organ of Corti are generally classified into two kinds; hair cells, which transduce the mechanical stimuli of sound to the cell membrane electrical potential differences, and supporting cells. These cells emerge from homogeneous prosensory epithelium through cell fate determination and differentiation. In the organ of Corti organogenesis, cell differentiation and the rearrangement of their position proceed in parallel, resulting in a characteristic alignment of mature hair cells and supporting cells. Recently, studies have focused on the signaling molecules and transcription factors that regulate cell fate determination and differentiation processes. In comparison, less is known about the mechanism of the formation of the tissue architecture; however, this is important in the morphogenesis of the organ of Corti. Thus, this review will introduce previous findings that focus on how cell fate determination, cell differentiation, and whole tissue morphogenesis proceed in a spatiotemporally and finely coordinated manner. This overview provides an insight into the regulatory mechanisms of the coordination in the developing organ of Corti.

Elevated Nectin-2 expression is involved in esophageal squamous cell carcinoma by promoting cell migration and invasion

Nectin-2 is overexpressed in cancer cells and is associated with poor prognosis in patients with various types of cancers. However, its involvement in esophageal squamous cell carcinoma (ESCC) remains unknown. The present study aimed to investigate the expression pattern of Nectin-2, its clinical significance and its roles in the malignant phenotypes of ESCC. Expression levels of Nectin-2 mRNA and protein were respectively detected by reverse transcription-quantitative polymerase chain reaction, western blotting and immunohistochemistry, based on 106 newly diagnosed ESCC patients. The associations between Nectin-2 expression and clinicopathological characteristics of ESCC patients were statistically analyzed. The effects of Nectin-2 in migration and invasion were then determined by wound healing and Transwell assays performed using ESCC cell lines (ECA109 and KYSE510) transfected with small interfering (si) RNA against Nectin-2. It was found that Nectin-2 expression was significantly elevated at the mRNA and protein levels in ESCC tissues, compared with the normal esophageal mucosa (P<0.001). Nectin-2-positive immunoreactivity was mainly localized in the cytoplasm of cancer cells in ESCC tissues. In addition, the expression levels of Nectin-2 protein in ESCC tissues with advanced tumor stage (P=0.006) and poor differentiation (P=0.02) were increased compared with patients with early tumor stage and well to moderate differentiation. Additionally, knockdown of Nectin-2 in the 2 ESCC cell lines could effectively suppress the cell migration and invasion abilities (P<0.05). In conclusion, these findings revealed that Nectin-2 is generally overexpressed in ESCC and associated with aggressive cancer progression. The present data also indicated that the silencing of Nectin-2 with siRNA in ESCC cells may inhibit cell malignant biological properties, indicating its potential as a potential marker or a therapeutic target for ESCC.

Nectin-4 promotes gastric cancer progression via the PI3K/AKT signaling pathway

Nectin-4, a member of the Nectin family that includes 4 Ca+-independent immunoglobulin-like cell adhesion molecules, plays a carcinogenic role in multiple cancers. However, Nectin-4 expression and its biological role in gastric cancer (GC) remain largely unknown. In this study, quantitative real-time polymerase chain reaction, Western blotting, and immunohistochemistry were used to evaluate the expression patterns of Nectin-4 in GC specimens and cell lines. We observed that high expression of Nectin-4 in GC patients was associated with TNM stage and lymph node metastasis status, and poor prognosis. In addition, cell proliferation and cell migration assays in vitro and tumorigenicity in vivo were performed to observe the effects of up-regulation and down-regulation of Nectin-4 expression on GC cell phenotypes. In further studies, the PI3K/AKT signaling pathway was revealed to be involved in Nectin-4-mediated GC progression. These results demonstrated that Nectin-4 had a promoter effect on human GC cell growth and motility, indicating that Nectin-4 may serve as an effective therapeutic target in GC.

Identification and validation of an 18-gene signature highly-predictive of bladder cancer metastasis

We found two deviant groups that were unpredictable with clinical models predicting bladder cancer metastasis. The group G consists of patients at high risk of pN+ , but they have pN0. The group P consists of patients at low risk of pN+ , but they have pN+ . We aimed to determine the genetic differences between these two groups. 1603 patients from SEER database were enrolled to build a multivariate model. This model was applied to patients from the TCGA database to distinguish groups G and P. Differentially expressed genes between the two groups were identified. RT-qPCR was used to validate the results in a cohort from FUSCC. Two deviant groups were identified both in the SEER population and the TCGA population. Expression of 183 genes was significantly different between the two groups. 18 genes achieved significant statistical power in predicting lymph node metastasis excluding these two deviant groups. The 18-gene signature outperformed 3 other bladder cancer lymph node prediction tools in 2 external GEO datasets. RT-qPCR results of our own cohort identified NECTIN2 (P = 0.036) as the only gene that could predict metastasis. Our study showed a novel gene screening method and proposed an 18-gene signature highly predictive of bladder cancer metastasis.

TIGIT and CD96: new checkpoint receptor targets for cancer immunotherapy

While therapies targeting the co-inhibitory or immune checkpoint receptors PD-1 and CTLA-4 have shown remarkable success in many cancers, not all patients benefit from these therapies. This has catalyzed enormous interest in the targeting of other immune checkpoint receptors. In this regard, TIGIT and CD96 have recently entered the limelight as novel immune checkpoint receptor targets. TIGIT and CD96 together with the co-stimulatory receptor CD226 form a pathway that is analogous to the CD28/CTLA-4 pathway, in which shared ligands and differential receptor:ligand affinities fine-tune the immune response. Although the roles of TIGIT and CD96 as immune checkpoint receptors in T cell and natural killer cell biology are just beginning to be uncovered, accumulating data support the targeting of these receptors for improving anti-tumor immune responses. A clear understanding of the immune cell populations regulated by TIGIT and CD96 is key to the design of immunotherapies that target these receptors in combination with other existing immune checkpoint blockade therapies.