The Ubiquitin-proteasome pathway regulates Nectin2/CD112 expression and impairs NK cell recognition and killing.

Nectin2 is a member of immunoglobulin-like cell adhesion molecules and plays a prominent role in the establishment of adherens and tight junctions. It is also upregulated on the surface of tumor and virus-infected cells where it functions as a ligand for the activating receptor CD226, thus contributing to cytotoxic lymphocyte-mediated recognition and killing of damaged cells. Little is currently known about the regulation of Nectin2 expression and, in particular, whether posttranscriptional and posttranslational mechanisms are involved. Here, we analyzed Nectin2 expression on a panel of human tumor cell lines and primary cultures and we found that Nectin2 is mainly expressed in cytoplasmic pools. Moreover, we demonstrated that ubiquitination of Nectin2 promotes its degradation and is responsible for protein intracellular retention. Indeed, inhibition of the ubiquitin pathway results in increased Nectin2 surface expression and enhances tumor cell susceptibility to NK cell cytotoxicity. Our results demonstrate a previously unknown mechanism of Nectin2 regulation revealing that the ubiquitin pathway represents a potential target of intervention in order to increase susceptibility to NK cell-mediated lysis.

Identification of targets for prostate cancer immunotherapy.

BACKGROUND: We performed profiling of the immune microenvironment of castration-resistant (CRPC) and castration-sensitive (CSPC) prostate cancer (PC) in order to identify novel targets for immunotherapy. METHODS: PD-L1 and CD3/CD8 immunohistochemistry, PD-L1/2 fluorescent in situ hybridization, tumor mutation burden, microsatellite instability, and RNA-seq of 395 immune-related genes were performed in 19 CRPC and CSPC. Targeted genomic sequencing and fusion analysis were performed in 17 of these specimens. RESULTS: CD276, PVR, and NECTIN2 were highly expressed in PC. Comparison of CRPC versus CSPC and primary versus metastatic tissue revealed the differential expression of immunostimulatory, immunosuppressive, and epithelial-to-mesenchymal transition (EMT)-related genes. Unsupervised clustering of differentially expressed genes yielded two final clusters best segregated by CRPC and CSPC status. CONCLUSION: CD276 and the alternative checkpoint inhibition PVR/NECTIN2/CD226/TIGIT pathway emerged as relevant to PC checkpoint inhibition target development.

Nectin-3 is a new biomarker that mediates the upregulation of MMP2 and MMP9 in ovarian cancer cells.

Nectin-3 is a cell adhesion molecule that functions in tight junctions. Recent reports have implicated nectin-3 in pancreatic adenocarcinoma and lung adenocarcinoma. However, there has been little exploration of the expression, cellular invasion and migration of nectin-3 in ovarian cancer (OC). We evaluated the distribution of cells that were positive for nectin-3 using immunohistochemistry in specimens of human OC and correlated these results with overall survival (OS). The nectin-3 expression was significantly increased accompanied by a degree of malignancy in ovarian tumors; moreover, the expression of matrix metallopeptidases (MMP) 2 and 9 was upregulated. In addition, an increased level of nectin-3 was related to a poorer OS. In summary, we have demonstrated that cellular migration and invasion via nectin-3 mediate the upregulation of MMP2 and MMP9 in OC cells. Nectin-3 may be a new biomarker for OC diagnosis.

Nectin1 expression is frequently decreased in gastric cancers.

Gastric cancer (GC) is rich in many different histological types, but how the histological pattern is defined remains to be proved. The relation between GC histological types and the expression of nectin1, which is one of the cell adhesion molecules that composes adherens junction, has not been reported. According to a publicly available database of 406 GC patients, the median overall survival of Nectin1 high expression patients was 55.4 months and that of low expression patients was 25.6 months (P = 0.0246). Using surgically or endoscopically resected GC samples, nectin1 expression was analyzed by immunohistochemistry. Nectin1 expressed at adherens junction in all the normal epithelial cells. However, nectin1 expressed not at adherens junction but at apical membrane in epithelial cells in intestinal metaplasia. The expression pattern of nectin1 in intestinal type GC resembled to intestinal metaplasia. In order to analyze the difference in nectin1 expression between GC histological types, a total of 116 intestinal type GC and 33 diffuse type GC. The expression of necitin1 in diffuse type GC (3.0%) was remarkably decreased compared to that in intestinal type GC (65.5%) (P < 0.0001). In conclusion, this is the first report showing an association between nectin1 expression and histological subtypes of GC.

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.