The cell adhesion nectin-like molecules (Necl) 1 and 4 suppress the growth and tumorigenic ability of colon cancer cells

Dual role of CASP8AP2/FLASH in regulating epithelial-to-mesenchymal transition plasticity (EMP)

BACKGROUND

Epithelial-to-mesenchymal transition (EMT) is a developmental program that consists of the loss of epithelial features concomitant with the acquisition of mesenchymal features. Activation of EMT in cancer facilitates the acquisition of aggressive traits and cancer invasion. EMT plasticity (EMP), the dynamic transition between multiple hybrid states in which cancer cells display both epithelial and mesenchymal markers, confers survival advantages for cancer cells in constantly changing environments during metastasis.

METHODS

RNAseq analysis was performed to assess genome-wide transcriptional changes in cancer cells depleted for histone regulators FLASH, NPAT, and SLBP. Quantitative PCR and Western blot were used for the detection of mRNA and protein levels. Computational analysis was performed on distinct sets of genes to determine the epithelial and mesenchymal score in cancer cells and to correlate FLASH expression with EMT markers in the CCLE collection.

RESULTS

We demonstrate that loss of FLASH in cancer cells gives rise to a hybrid E/M phenotype with high epithelial scores even in the presence of TGFβ, as determined by computational methods using expression of predetermined sets of epithelial and mesenchymal genes. Multiple genes involved in cell-cell junction formation are similarly specifically upregulated in FLASH-depleted cells, suggesting that FLASH acts as a repressor of the epithelial phenotype. Further, FLASH expression in cancer lines is inversely correlated with the epithelial score. Nonetheless, subsets of mesenchymal markers were distinctly up-regulated in FLASH, NPAT, or SLBP-depleted cells.

CONCLUSIONS

The ZEB1low/SNAILhigh/E-cadherinhigh phenotype described in FLASH-depleted cancer cells is driving a hybrid E/M phenotype in which epithelial and mesenchymal markers coexist.

SynCAMs in Normal Vertebrate Neural Development and Neuropsychiatric Disorders: from the Perspective of the OCAs

Neuronal synaptic junctions connect neurons to enable neuronal signal transmission in the nervous system. The proper establishment of synaptic connections required many adhesion molecules. Malfunctions of these adhesion molecules can result in neural development disorders and neuropsychiatric disorders. How specific synapses are established by various adhesion molecules for proper neural circuitry is a fundamental question of neuroscience. SynCAMs, also named CADMs, Necl, etc., are among the many adhesion proteins found in synapses. Here, we review the current understanding of the physical properties of SynCAMs and their roles in axon pathfinding, myelination, synaptogenesis, and synaptic plasticity. In addition, we discuss the involvement of SynCAMs in neuropsychiatric disorders. Finally, we propose that SynCAM functions can be better viewed and understood from the perspective of orientational cell adhesions (OCAs). In particular, we discuss the possibilities of how SynCAMs can be regulated at the cell-type specific expression, transcription variants, posttranslational modification, and subcellular localization to modulate the diversity of SynCAMs as OCA molecules. Being major components of the synapses, SynCAMs continue to be an important research topic of neuroscience, and many outstanding questions are waiting to be answered.

Clinicopathological Significance of Cell Adhesion Molecule 4 Expression in Gallbladder Cancer and Its Prognostic Role

Cell adhesion molecule 4 (CADM4) is involved in intercellular interactions and is a tumor-suppressor candidate. The role of CADM4 in gallbladder cancer (GBC) has not been reported. Therefore, the clinicopathological significance and prognostic value of CADM4 expression in GBC were evaluated in the present study. Immunohistochemistry (IHC) was performed on 100 GBC tissues to assess CADM4 expression at the protein level. The association between CADM4 expression and the clinicopathological characteristics of GBC was analyzed, and the prognostic significance of CADM4 expression was evaluated. Low CADM4 expression was significantly associated with advanced T category (p = 0.010) and high AJCC stage (p = 0.019). In a survival analysis, low CADM4 expression was associated with shorter overall survival (OS; p = 0.001) and recurrence-free survival (RFS; p = 0.018). In univariate analyses, low CADM4 expression was associated with shorter OS (p = 0.002) and RFS (p = 0.023). In multivariate analyses, low CADM4 expression was an independent prognostic factor of OS (p = 0.013). Low CADM4 expression was associated with tumor invasiveness and poor clinical outcomes in patients with GBC. CADM4 may play an important role in cancer progression and patient survival and can be used as a potential prognostic marker of GBC.

Integrated multi-omics approach to distinct molecular characterization and classification of early-onset colorectal cancer

Incidence of early-onset colorectal cancer (EOCRC), defined by a diagnosed age under 50 years, is increasing, but its heterogeneous etiologies that differ from general CRC remain undetermined. We initially characterize the genome, epigenome, transcriptome, and proteome of tumors from 79 patients in a Chinese CRC cohort. Data for an additional 126 EOCRC subjects are obtained from the International Cancer Genome Consortium Chinese cohort and The Cancer Genome Atlas European cohort. We observe that early-onset tumors have a high tumor mutation burden; increased DNA repair features by mutational signature 3 and multi-layer pathway enrichments; strong perturbations at effects of DNA methylation and somatic copy-number alteration on gene expression; and upregulated immune infiltration as hot tumors underlying immunophenotypes. Notably, LMTK3 exhibits ancestral mutation disparity, potentially being a functional modulator and biomarker that drives molecular alterations in EOCRC development and immunotherapies. This integrative omics study provides valuable knowledge for precision oncology of CRC.

Nectins and Nectin-like Molecules in Colorectal Cancer: Role in Diagnostics, Prognostic Values, and Emerging Treatment Options: A Literature Review

In 2020, colorectal cancer was the third most common type of cancer worldwide with a clearly visible increase in the number of cases each year. With relatively high mortality rates and an uncertain prognosis, colorectal cancer is a serious health problem. There is an urgent need to investigate its specific mechanism of carcinogenesis and progression in order to develop new strategies of action against this cancer. Nectins and Nectin-like molecules are cell adhesion molecules that take part in a plethora of essential processes in healthy tissues as well as mediating substantial actions for tumor initiation and evolution. Our understanding of their role and a viable application of this in anti-cancer therapy has rapidly improved in recent years. This review summarizes the current data on the role nectins and Nectin-like molecules play in colorectal cancer.

Decreased Expression of Cell Adhesion Molecule 4 in Gastric Adenocarcinoma and Its Prognostic Implications

Cell adhesion molecule 4 (CADM4) is a novel tumor suppressor candidate. The prognostic implications of CADM4 in gastric cancer have not been conclusively elucidated. Therefore, we evaluated the clinicopathological significance and prognostic value of CADM4 expression in a large series of patients with gastric adenocarcinoma. Immunohistochemical staining for CADM4 was performed on 534 gastric adenocarcinomas. We evaluated the associations between CADM4 expression and the clinicopathological and molecular characteristics of the adenocarcinomas. The prognostic effect of CADM4 expression was evaluated by survival analyses. Low CADM4 expression was significantly associated with young age (p = 0.046), aggressive histological type (p < 0.001), high pT category (p < 0.001), nodal metastasis (p < 0.001), high stage (p = 0.002), lymphovascular invasion (p = 0.001), and perineural invasion (p = 0.001). Low CADM4 expression was more frequently observed in tumors without human epidermal growth factor receptor 2 (HER2) amplification (p = 0.002). Low CADM4 expression was associated with worse overall survival (p = 0.007) and recurrence-free survival (p = 0.005) in the survival analyses. Low CADM4 expression was associated with aggressive clinicopathological features and poor clinical outcomes. CADM4 can act as a tumor suppressor in gastric adenocarcinoma and can be considered a prognostic biomarker.

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.

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.

An oncolytic adenovirus delivering TSLC1 inhibits Wnt signaling pathway and tumor growth in SMMC-7721 xenograft mice model

Tumor suppressor in lung cancer-1 (TSLC1) was first identified as a tumor suppressor for lung cancer, and frequently downregulated in various types of cancers including hepatocellular carcinoma (HCC). The Wnt pathway plays a critical role in tumorigenesis, migration, and invasion in HCC. However, the function of TSLC1 in modulating Wnt signaling in HCC is unclear. In this study, we evaluated the effect of TSLC1-armed oncolytic adenovirus (S24-TSLC1) on the Wnt/β-catenin pathway, cell viability, invasion and migration abilities of HCC in vitro and the growth of SMMC-7721-xenografted tumor in mice model. We detected the expression of TSLC1 in tumor samples and HCC cell lines. The results showed that TSLC1 expression was low in HCC, but high in pericarcinomatous tissue and normal cells, which implied that TSLC1 is a tumor suppressor of liver cancer. S24-TSLC1 exhibited an antitumor effect on HCC cell growth in vitro, but did little damage to normal liver cells. Overexpression of TSLC1 downregulated the transcriptional activity of TCF4/β-catenin and inhibited the mRNA or protein expression of Wnt target genes cyclinD1 and c-myc. S24-TSLC1 also inhibited the invasion and migration of HCC cells. Animal experiments further confirmed that S24-TSLC1 significantly inhibited tumor growth of the SMMC-7721-xenografted tumor. In conclusion, TSLC1 could downregulate the Wnt signal pathway and suppress HCC cell growth, migration and invasion, suggesting that S24-TSLC1 may be a potent antitumor agent for future clinical trials in liver cancer treatment.

High expression of cell adhesion molecule 2 unfavorably impacts survival in non-small cell lung cancer patients with brain metastases

Background

Lung cancer is one kind of malignant tumor with a high risk for morbidity and mortality compared to other solid organ malignancies. Brain metastases occur in 30-55% of non-small cell lung cancer (NSCLC) patients. Prognosis of NSCLC patients with brain metastases is very poor. Our previous study showed that cell adhesion molecule 2 (CADM2) could regulate the development of brain metastasis in NSCLC cells. Therefore, the objective of the study is to evaluate the effect of CADM2 on the prognosis of NSCLC patients with brain metastases.

Methods

The expression of CADM2 was detected by quantitative real-time polymerase chain reaction (qRT-PCR) in the tissue of the primary tumor. Patients were followed up and overall survival (OS) was calculated. The relationships between CADM2 and clinicopathological features were analyzed using the chi-square test. Kaplan-Meier analysis was carried out to demonstrate the influence of CADM2 on the OS of patients. Univariate and multivariate Cox analyses were used to determine the prognosis of NSCLC patients with brain metastases.

Results

A total of 139 NSCLC patients with brain metastases from the Affiliated Cancer Hospital & Institute of Guangzhou Medical University, treated between January 2015 and December 2017 were evaluated retrospectively. The expression level of CADM2 in patients ranged from 1 to 17.2677, with a median of 6.0772. Chi-square analysis showed that CADM2 gene expression level was not significantly associated with gender, age, tumor location, histological subtype, tumor T stage, extracranial metastasis, or smoking status. However, CADM2 expression was notably associated with risk for lymph node metastasis. The results of the Kaplan-Meier analysis showed that high expression [CADM2 messenger RNA (mRNA) ≥6.0772] of CADM2 was markedly associated with poor prognosis. Univariate and multivariate Cox analyses demonstrated that CADM2 was an independent risk factor for survival in NSCLC patients with brain metastases (P<0.05).

Conclusions

CADM2 expression is up-regulated and closely associated with disease progression and poor prognosis in NSCLC patients with brain metastases. CADM2 expression warrants special consideration given its potential prognostic significance that might help inform clinical decision making.

Cell adhesion molecule 4 suppresses cell growth and metastasis by inhibiting the Akt signaling pathway in non-small cell lung cancer

Cell adhesion molecule 4 (CADM4) is downregulated in many human cancers. However, CADM4 expression levels in human non-small cell lung cancer (NSCLC) tissues and its roles in NSCLC progression remain unknown. Our study aims to address these issues. We examined CADM4 levels in NSCLC tissues using real-time PCR and western blot. A549 and NCI-H1299 cells were then transfected with pcDNA3.1-CADM4 plasmid or siCADM4 to overexpress or knock down CADM4. Cell proliferation, cell cycle distribution, migration, and invasion were evaluated. NSCLC cells transfected with pcDNA3.1-CADM4 plasmid or siCADM4 were treated with SC79 or LY294002, respectively, to investigate the involvement of the Akt signaling pathway. Male nude mice were subcutaneously injected with stably transfected cells (1 × 10⁶ cells/mice) to observe tumor growth. Stable transfectants were injected into nude mice (1 × 10⁶ cells/mice) via tail vein to observe tumor metastasis. The results showed that CADM4 gene and protein levels in NSCLC tissues were significantly lower than those in corresponding adjacent tissues. CADM4 overexpression markedly inhibited cell proliferation, migration, and invasion. We also found that matrix metalloproteinase 9 (MMP-9) and MMP-2 activities were reduced. Moreover, CADM4 overexpression arrested the cell cycle at G1 phase, with the changes in expression of cell cycle regulators. The Akt signaling pathway was inhibited by CADM4 overexpression. In contrast, CADM4 knockdown showed the opposite effects. Additionally, SC79 and LY294002 reversed the effects of CADM4 overexpression and CADM4 knockdown in vitro, respectively. In xenograft models, CAMD4 overexpression suppressed, while CADM4 knockdown promoted tumor growth, accompanied by changes in Ki67 expression. In in vivo metastasis assay, CADM4 overexpression decreased, while CADM4 knockdown increased numbers of metastatic nodules in lung and liver. These evidences suggest that CADM4 may regulate NSCLC progression via the Akt signaling pathway. CADM4 may be a potential therapeutic target for NSCLC.

Genome-wide methylation and expression profiling identify methylation-associated genes in colorectal cancer

Aim: To identify methylation-associated genes in the carcinogenesis of colorectal cancer (CRC). Materials & methods: Genome-wide patterns of DNA methylation and gene expression in CRC tissues and adjacent normal tissues were determined and further validated in The Cancer Genome Atlas data and Chinese CRC patients, respectively. Gene overexpression and knockdown cells were constructed to investigate their biological roles in CRC. Results: After validations, hypermethylation of eight genes were found to be correlated with their reduced transcription, and hypomethyaltion of three genes were associated with their upregulation. CADM3, CNRIP1, GRHL2, GRIA4, GSTM2 and NRXN1 were associated with the overall survival of CRC patients. CNRIP1 and GSTM2 were mainly responsible for the proliferation in CRC cells. Conclusion: A total of 11 genes may be promising biomarkers for CRC.

CADM1 is a TWIST1-regulated suppressor of invasion and survival

Metastatic cancer remains a clinical challenge; however, patients diagnosed prior to metastatic dissemination have a good prognosis. The transcription factor, TWIST1 has been implicated in enhancing the migration and invasion steps within the metastatic cascade, but the range of TWIST1-regulated targets is poorly described. In this study, we performed expression profiling to identify the TWIST1-regulated transcriptome of melanoma cells. Gene ontology pathway analysis revealed that TWIST1 and epithelial to mesenchymal transition (EMT) were inversely correlated with levels of cell adhesion molecule 1 (CADM1). Chromatin immunoprecipitation (ChIP) studies and promoter assays demonstrated that TWIST1 physically interacts with the CADM1 promoter, suggesting TWIST1 directly represses CADM1 levels. Increased expression of CADM1 resulted in significant inhibition of motility and invasiveness of melanoma cells. In addition, elevated CADM1 elicited caspase-independent cell death in non-adherent conditions. Expression array analysis suggests that CADM1 directed non-adherent cell death is associated with loss of mitochondrial membrane potential and subsequent failure of oxidative phosphorylation pathways. Importantly, tissue microarray analysis and clinical data from TCGA indicate that CADM1 expression is inversely associated with melanoma progression and positively correlated with better overall survival in patients. Together, these data suggest that CADM1 exerts tumor suppressive functions in melanoma by reducing invasive potential and may be considered a biomarker for favorable prognosis.

Structure of the heterophilic interaction between the nectin-like 4 and nectin-like 1 molecules

Nectin-like (Necl) molecules are Ca²⁺-independent Ig-like transmembrane cell adhesion molecules that participate in junctions between different cell types. The specific cell-cell adhesions mediated by Necl proteins are important in neural development and have been implicated in neurodegenerative diseases. Here, we present the crystal structure of the mouse Necl-4 full ectodomain and the structure of the heterophilic Necl ectodomain complex formed by the mNecl-4 and mNecl-1 ectodomains. We demonstrate that, while the ectodomain of mNecl-4 is monomeric, it forms a stable heterodimer with Ig1 of mNecl-1, with an affinity significantly higher than that observed for self-dimerization of the mNecl-1 ectodomain. We validated our structural characterizations by performing a surface plasmon resonance assay and an Fc fusion protein binding assay in mouse primary dorsal root ganglia neurites and Schwann cells and identified a selection of residues important for heterophilic interactions. Finally, we proposed a model of Necl binding specificity that involves an induced-fit conformational change at the dimerization interface.

Genome-wide identification of microRNAs in decidual natural killer cells from patients with unexplained recurrent spontaneous abortion

PROBLEM

This study revealed miRNA regulation and functional microarray-based profiles of miRNAs in the natural killer (NK) cells of the decidual tissue obtained from patients with unexplained recurrent spontaneous abortion (URSA).

METHOD OF STUDY

Patients with URSA were categorized based on the occurrence of at least two or more successive spontaneous abortions between 7th and 10th gestational week. Total RNA was isolated from the NK cells of the decidual tissue obtained from patients with induced abortion at about the 8th gestational week. The potential contribution of regulatory miRNAs to a genetic predisposition to URSA was characterized by comparison with healthy and fertile controls and bioinformatics analyses.

RESULTS

Analysis of the miRNA expression profiles identified 50 miRNAs that were differentially expressed, including one down-regulated and 49 up-regulated miRNAs in the URSA group. MiRNA-Gene-Network, miRNA-GO-Network and miRNA-Gene-TF-Network were constructed. The key miRNAs, genes, GOs and core TFs in the network were determined.

CONCLUSION

Our results suggest that a close relationship exists between the aberrant miRNAs and URSA. Furthermore, these findings support the notion that altered expression of miRNAs may contribute to the clinical diagnosis of URSA and the potential to develop novel strategies for therapeutic targets against URSA.

CADM2, as a new target of miR-10b, promotes tumor metastasis through FAK/AKT pathway in hepatocellular carcinoma

BACKGROUND

Cell adhesion molecules (CADMs) comprise of a protein family whose functions include maintenance of cell polarity and tumor suppression. Hypo-expression of CADM2 gene expression has been observed in several cancers including hepatocellular carcinoma (HCC). However, the role and mechanisms of CADM2 in HCC remain unclear.

METHODS

The expression of CADM2 and miRNA-10b (miR-10b) in HCC tissues and cell lines were detected using real-time PCR and Western blotting. Immunofluorescence was used to detect Epithelial-mesenchymal transition (EMT) progression in HCC cell lines. Dual-luciferase reporter assay was used to determine miR-10b binding to CADM2 3'UTR. Wound healing assay and Transwell assay were performed to examine the migration and invasion of HCC cells.

RESULTS

We report the effect of CADM2 as a tumor suppressor in HCC. Firstly, we confirmed that CADM2 expression was significantly down regulated in HCC tissues compared to normal tissues according to TCGA data analysis and fresh HCC sample detection. Secondly, overexpression of CADM2 could inhibit EMT process, migratory and invasion ability of HCC cells. Furthermore, the results indicated that CADM2 is a direct target of miR-10b in HCC cells and miR-10b/CADM2 modulates EMT process and migration ability via focal adhesion kinase (FAK) /AKT signaling pathway in HCC.

CONCLUSIONS

Our study demonstrates that miR-10b-CADM2-FAK/AKT axis plays an important role in HCC metastasis, which might be a novel potential therapeutic option for HCC treatment.

Clinicopathological significance of Necl-4 expression in pancreatic ductal adenocarcinoma

AIMS

The loss, or decreased expression, of nectin-like molecule 4 (Necl-4; an immunoglobulin-like cell adhesion molecule) is reported to be associated with the development and progression of certain types of cancer. We investigated the clinicopathological significance of Necl-4 expression in patients with pancreatic ductal adenocarcinoma (PDAC).

METHODS

Immunohistochemical analyses of Necl-4 (n=258) and E-cadherin (n=256) expression were performed using tissue microarray blocks of PDAC samples. Necl-4 expression of 38 pancreatic intraepithelial neoplasia (PanIN) lesions included in tissue microarray cores was also evaluated. Necl-4 and E-cadherin expression was considered positive if >30% of cells were stained, and negative if ≤30% of cells were stained.

RESULTS

Necl-4 expression was positive in 45.7% (n=118) and negative in 54.3% (n=140) of PDAC cases. Necl-4 staining was positive in 96.7% (n=29) and negative in 3.3% (n=1) of low-grade PanIN cases, and positive in 62.5% (n=5) and negative in 37.5% (n=3) of high-grade PanIN cases. The number of cases with positive Necl-4 expression decreased in the order low-grade PanIN>high-grade PanIN>PDAC (p<0.001). Negative Necl-4 expression was significantly associated with a larger tumour size of >30 mm, perineural invasion, lymphatic involvement, lymph node metastasis (pN1), an advanced TNM (tumour, node, metastases) stage (stage IIB-IV), an advanced histological grade (G2/3), and shorter overall survival. E-cadherin staining was positive in 46.1% (n=118) and negative in 53.9% (n=138) of PDAC cases. Necl-4 expression correlated positively with E-cadherin expression (r=0.405, p<0.001).

CONCLUSIONS

The results suggest that Necl-4 is associated with carcinogenesis and aggressiveness of PDAC.

Necl 4 and RNase 5 Are Important Biomarkers for Gastric and Colon Adenocarcinomas

BACKGROUND There is a need to identify new prognostic factors that may be used in addition to the known risk factors in gastrointestinal adenocarcinomas. In this study, we aimed to determine the expression of Necl 4 and RNase 5 biomarkers in gastric and colon adenocarcinomas, as well as the prognostic efficacy of these biomarkers in gastric and colon adenocarcinomas. MATERIAL AND METHODS Ninety-two cases resected due to stomach and colon adenocarcinoma were included in the study. The expression of Necl 4 and RNase 5 biomarkers was evaluated by immunohistochemical staining of the stomach and colon normal mucosa and adenocarcinoma areas. RESULTS In colon adenocarcinomas, there was a significant association between Necl 4 and lymphovascular invasion, vascular invasion, and perineural invasion (p<0.05). There was a significant association between RNase 5 and histological differentiation in colon adenocarcinomas (p<0.05). There was no association between RNase 5 and Necl 4 in gastric or colon adenocarcinomas. CONCLUSIONS Necl 4 may have prognostic value in colon adenocarcinomas, but it is difficult to ascertain in gastric adenocarcinomas.

Measles Virus Enters Breast and Colon Cancer Cell Lines through a PVRL4-Mediated Macropinocytosis Pathway

Measles virus (MeV) is a member of the family Paramixoviridae that causes a highly contagious respiratory disease but has emerged as a promising oncolytic platform. Previous studies of MeV entry focused on the identification of cellular receptors. However, the endocytic and trafficking pathways utilized during MeV entry remain poorly described. The contribution of each endocytic pathway has been examined in cells that express the MeV receptors SLAM (signaling lymphocyte-activating molecule) and PVRL4 (poliovirus receptor-like 4) (nectin-4). Recombinant MeVs expressing either firefly luciferase or green fluorescent protein together with a variety of inhibitors were used. The results showed that MeV uptake was dynamin independent in the Vero.hPVRL4, Vero.hSLAM, and PVRL4-positive MCF7 breast cancer cell lines. However, MeV infection was blocked by 5-(N-ethyl-N-propyl)amiloride (EIPA), the hallmark inhibitor of macropinocytosis, as well as inhibitors of actin polymerization. By using phalloidin staining, MeV entry was shown to induce actin rearrangements and the formation of membrane ruffles accompanied by transient elevated fluid uptake. Small interfering RNA (siRNA) knockdown of p21-activated kinase 1 (PAK1) demonstrated that MeV enters both Vero.hPVRL4 and Vero.hSLAM cells in a PAK1-independent manner using a macropinocytosis-like pathway. In contrast, MeV entry into MCF7 human breast cancer cells relied upon Rac1 and its effector PAK1 through a PVRL4-mediated macropinocytosis pathway. MeV entry into DLD-1 colon and HTB-20 breast cancer cells also appeared to use the same pathway. Overall, these findings provide new insight into the life cycle of MeV, which could lead to therapies that block virus entry or methods that improve the uptake of MeV by cancer cells during oncolytic therapy.IMPORTANCE In the past decades, measles virus (MeV) has emerged as a promising oncolytic platform. Previous studies concerning MeV entry focused mainly on the identification of putative receptors for MeV. Nectin-4 (PVRL4) was recently identified as the epithelial cell receptor for MeV. However, the specific endocytic and trafficking pathways utilized during MeV infections are poorly documented. In this study, we demonstrated that MeV enters host cells via a dynamin-independent and actin-dependent endocytic pathway. Moreover, we show that MeV gains entry into MCF7, DLD-1, and HTB-20 cancer cells through a PVRL4-mediated macropinocytosis pathway and identified the typical cellular GTPase and kinase involved. Our findings provide new insight into the life cycle of MeV, which may lead to the development of therapies that block the entry of the virus into the host cell or alternatively promote the uptake of oncolytic MeV into cancer cells.

SRC-2-mediated coactivation of anti-tumorigenic target genes suppresses MYC-induced liver cancer

Hepatocellular carcinoma (HCC) is the fifth most common solid tumor in the world and the third leading cause of cancer-associated deaths. A Sleeping Beauty-mediated transposon mutagenesis screen previously identified mutations that cooperate with MYC to accelerate liver tumorigenesis. This revealed a tumor suppressor role for Steroid Receptor Coactivator 2/Nuclear Receptor Coactivator 2 (Src-2/Ncoa2) in liver cancer. In contrast, SRC-2 promotes survival and metastasis in prostate cancer cells, suggesting a tissue-specific and context-dependent role for SRC-2 in tumorigenesis. To determine if genetic loss of SRC-2 is sufficient to accelerate MYC-mediated liver tumorigenesis, we bred Src-2-/- mice with a MYC-induced liver tumor model and observed a significant increase in liver tumor burden. RNA sequencing of liver tumors and in vivo chromatin immunoprecipitation assays revealed a set of direct target genes that are bound by SRC-2 and exhibit downregulated expression in Src-2-/- liver tumors. We demonstrate that activation of SHP (Small Heterodimer Partner), DKK4 (Dickkopf-4), and CADM4 (Cell Adhesion Molecule 4) by SRC-2 suppresses tumorigenesis in vitro and in vivo. These studies suggest that SRC-2 may exhibit oncogenic or tumor suppressor activity depending on the target genes and nuclear receptors that are expressed in distinct tissues and illuminate the mechanisms of tumor suppression by SRC-2 in liver.

Serum nectin-2 levels are diagnostic and prognostic in patients with colorectal carcinoma

INTRODUCTION

Nectins are a family of integral protein and immunoglobulin-like cell adhesion molecules involved in the formation of functioning adherence and tight junctions. Aberrant expression is associated with cancer progression, apoptosis and cell proliferation but little is known how these effects change in cell behavior. The objective of this study was to evaluate the serum levels of nectin-2 with regard to diagnostic, predictive and prognostic value in colorectal cancer (CRC) patients.

MATERIALS AND METHODS

One-hundred and forty CRC patients were enrolled in this study. Serum nectin-2 levels were determined by enzyme-linked immunosorbent assay method. Age- and sex-matched 40 healthy controls were included in the analysis.

RESULTS

Median age of patients was 60 years old, range 24-84 years. The localization of tumor in majority of the patients was colon (n = 81, 58 %). Non-metastatic (stage II and III) and metastatic patients' baseline serum nectin-2 levels were significantly higher than those in the healthy control group (p < 0.001; for two group). However, known clinical variables including response to CTx (chemotherapy) were not found to be correlated with serum nectin-2 concentrations (p > 0.05). While non-metastatic group patients with elevated serum nectin-2 levels showed significant adverse effect on PFS, metastatic group patients with elevated serum nectin-2 levels showed no significant adverse effect on PFS (p = 0.05 and p = 0.29, respectively). On the other hand, our study results did not show statistically significant serum nectin-2 concentrations regarding overall survival rates.

CONCLUSION

Serum levels of nectin-2 may have diagnostic roles for CRC patients. Moreover, our study results show the prognostic role of nectin-2 in non-metastatic group patients.

Nectins and nectin-like molecules in development and disease

Nectins and nectin-like molecules (Necls)/Cadms are Ca(2+)-independent immunoglobulin superfamily cell adhesion molecules, expressed in most cell types. Nectins mediate not only homotypic but also heterotypic cell-cell adhesion, in contrast to classic cadherins which participate only in homophilic adhesion. Nectins and Necls function in organogenesis of the eye, inner ear, tooth, and cerebral cortex and in a variety of developmental processes including spermatogenesis, axon guidance, synapse formation, and myelination. They are also involved in various diseases, such as viral infection, hereditary ectodermal dysplasia, Alzheimer's disease, autism spectrum disorder, and cancer. Thus, nectins and Necls are crucial for both physiology and pathology. This review summarizes recent advances in research on these cell adhesion molecules in development and pathogenesis.

Low CADM2 expression predicts high recurrence risk of hepatocellular carcinoma patients after hepatectomy

PURPOSE

To investigate the expression and clinical significance of CADM2 in hepatocellular carcinomas (HCC).

METHODS

The level of expression of CADM2 mRNA was assessed in frozen tumor specimens and adjacent noncancerous tissues from 30 HCC patients by real-time PCR. The protein level was determined by immunohistochemistry on a tissue microarray containing tumor and adjacent noncancerous tissues from 234 HCC patients. Clinicopathological characteristics associated analysis was performed through SPSS18 .

RESULTS

CADM2 was strikingly down regulated in HCC. CADM2 expression was associated with differentiation (P = 0.000), serum alpha-fetoprotein (P = 0.003), vascular invasion (P = 0.001), and hepatitis B surface antigen (HBsAg, P = 0.038). Furthermore, patients with low CADM2 expression had significantly poorer recurrence-free survival (RFS) (40.8 and 34.2 % vs. 56.3 and 50.1 % in 3- and 5-year RFS, respectively, P = 0.005). Subgroup analysis revealed that the difference in RFS between groups with low- and high-CADM2 expression still existed among patients belonging to stage 0 or A of BCLC staging system (P = 0.008), patients with tumor ≤5 cm in size (P = 0.013), and alpha-fetoprotein-negative patients (P = 0.003). Moreover, low expression was more frequently observed in the early recurrence group (within 2 years, P = 0.007). Further multivariate Cox regression analysis indicated that CADM2 expression level, tumor size, tumor number, vascular invasion, HBsAg were independent risk factors for HCC recurrence.

CONCLUSION

CADM2 serves as a novel predictor of RFS in HCC patients after curative resection.

Interaction of Necl-4/CADM4 with ErbB3 and integrin α6 β4 and inhibition of ErbB2/ErbB3 signaling and hemidesmosome disassembly

Nectin-like molecule 4 (Necl-4)/CADM4, a transmembrane cell-cell adhesion molecule with three Ig-like domains, was shown to serve as a tumor suppressor, but its mode of action has not been elucidated. In this study, we showed that Necl-4 interacted in cis with ErbB3 through their extracellular regions, recruited PTPN13 and inhibited the heregulin-induced activation of the ErbB2/ErbB3 signaling. In addition, we extended our previous finding that Necl-4 interacts in cis with integrin α6 β4 through their extracellular regions and found that Necl-4 inhibited the phorbol ester-induced disassembly of hemidesmosomes. These results indicate that Necl-4 serves as a tumor suppressor by inhibiting the ErbB2/ErbB3 signaling and hemidesmosome disassembly.

RNA-Seq of human breast ductal carcinoma in situ models reveals aldehyde dehydrogenase isoform 5A1 as a novel potential target

Breast ductal carcinoma in situ (DCIS) is being found in great numbers of women due to the widespread use of mammography. To increase knowledge of DCIS, we determined the expression changes that are common among three DCIS models (MCF10.DCIS, SUM102 and SUM225) compared to the MCF10A model of non-tumorigenic mammary epithelial cells in three dimensional (3D) overlay culture with reconstituted basement membrane (rBM). Extracted mRNA was subjected to 76 cycles of deep sequencing (RNA-Seq) using Illumina Genome Analyzer GAIIx. Analysis of RNA-Seq results showed 295 consistently differentially expressed transcripts in the DCIS models. These differentially expressed genes encode proteins that are associated with a number of signaling pathways such as integrin, fibroblast growth factor and TGFβ signaling, show association with cell-cell signaling, cell-cell adhesion and cell proliferation, and have a notable bias toward localization in the extracellular and plasma membrane compartments. RNA-Seq data was validated by quantitative real-time PCR of selected differentially expressed genes. Aldehyde dehydrogenase 5A1 (ALDH5A1) which is an enzyme that is involved in mitochondrial glutamate metabolism, was over-expressed in all three DCIS models at both the mRNA and protein levels. Disulfiram and valproic acid are known to inhibit ALDH5A1 and are safe for chronic use in humans for other disorders. Both of these drugs significantly inhibited net proliferation of the DCIS 3D rBM overlay models, but had minimal effect on MCF10A 3D rBM overlay models. These results suggest that ALDH5A1 may play an important role in DCIS and potentially serve as a novel molecular therapeutic target.

Canonical Wnt suppressor, Axin2, promotes colon carcinoma oncogenic activity

Aberrant activation of canonical Wingless-type MMTV integration site family (Wnt) signaling is pathognomonic of colorectal cancers (CRC) harboring functional mutations in either adenomatous polyposis coli or β-catenin. Coincident with Wnt cascade activation, CRCs also up-regulate the expression of Wnt pathway feedback inhibitors, particularly the putative tumor suppressor, Axin2. Because Axin2 serves as a negative regulator of canonical Wnt signaling in normal cells, recent attention has focused on the utility of increasing Axin2 levels in CRCs as a means to slow tumor progression. However, rather than functioning as a tumor suppressor, we demonstrate that Axin2 acts as a potent promoter of carcinoma behavior by up-regulating the activity of the transcriptional repressor, Snail1, inducing a functional epithelial-mesenchymal transition (EMT) program and driving metastatic activity. Silencing Axin2 expression decreases Snail1 activity, reverses EMT, and inhibits CRC invasive and metastatic activities in concert with global effects on the Wnt-regulated cancer cell transcriptome. The further identification of Axin2 and nuclear Snail1 proteins at the invasive front of human CRCs supports a revised model wherein Axin2 acts as a potent tumor promoter in vivo.

Analysis of cell adhesion during early stages of colon cancer based on an extended multi-valued logic approach

Cell adhesion in the normal colon is typically associated with differentiated cells, whereas in cancerous colon it is associated with advanced tumors. For advanced tumors growing evidence supports the existence of stem-like cells that have originated from transdifferentiation. Because stem cells can also be transformed in their own niche, at the base of the Lieberkühn's crypts, we conjectured that cell adhesion can also be critical in early tumorigenesis. To assess this hypothesis we built an annotated, multi-valued logic model addressing cell adhesion of normal and tumorigenic stem cells in the human colon. The model accounts for (i) events involving intercellular adhesion structures, (ii) interactions involving cytoskeleton-related structures, (iii) compartmental distribution of α/β/γ/δ-catenins, and (iv) variations in critical cell adhesion regulators (e.g., ILK, FAK, IQGAP, SNAIL, Caveolin). We developed a method that can deal with graded multiple inhibitions, something which is not possible with conventional logical approaches. The model comprises 315 species (including 26 genes), interconnected by 269 reactions. Simulations of the model covered six scenarios, which considered two types of colonic cells (stem vs. differentiated cells), under three conditions (normal, stressed and tumor). Each condition results from the combination of 92 inputs. We compared our multi-valued logic approach with the conventional Boolean approach for one specific example and validated the predictions against published data. Our analysis suggests that stem cells in their niche synthesize high levels of cytoplasmatic E-cadherin and CdhEP(Ser684,686,692), even under normal-mitogenic stimulus or tumorigenic conditions. Under these conditions, E-cadherin would be incorporated into the plasmatic membrane, but only as a non-adhesive CdhE_β-catenin_IQGAP complex. Under stress conditions, however, this complex could be displaced, yielding adhesive CdhE_β-catenin((cis/trans)) complexes. In the three scenarios tested with stem cells, desmosomes or tight junctions were not assembled. Other model predictions include expected levels of the nuclear complex β-catenin_TCF4 and the anti-apoptotic protein Survivin for both normal and tumorigenic colonic stem cells.

Immunoglobulin superfamily receptors and adherens junctions

The immunogroblin (Ig) superfamily proteins characterized by the presence of Ig-like domains are involved in various cellular functions. The properties of the Ig-like domains to form rod-like structures and to bind specifically to other proteins make them ideal for cell surface receptors and cell adhesion molecules (CAMs). Ig-CAMs, nectins in mammals and Echinoid in Drosophila, are crucial components of cadherin-based adherens junctions in the epithelium. Nectins form cell-cell adhesion by their trans-interactions and recruit cadherins to the nectin-initiated cell-cell adhesion site to establish adherens junctions. Thereafter junction adhesion molecules, occludin, and claudins, are recruited to the apical side of adherens junctions to establish tight junctions. The recruitment of these molecules by nectins is mediated both by the direct and indirect interactions of afadin with many proteins, such as catenins, and zonula occludens proteins, and by the nectin-induced reorganization of the actin cytoskeleton. Nectins contribute to the formation of both homotypic and heterotypic types of cell-cell junctions, such as synapses in the brain, contacts between pigment and non-pigment cell layers of the ciliary epithelium in the eye, Sertoli cell-spermatid junctions in the testis, and sensory cells and supporting cells in the sensory organs. In addition, cis- and trans-interactions of nectins with various cell surface proteins, such as integrins, growth factor receptors, and nectin-like molecules (Necls) play important roles in the regulation of many cellular functions, such as cell polarization, movement, proliferation, differentiation, survival, and cell sorting. Furthermore, the Ig-CAMs are implicated in many human diseases including viral infections, ectodermal dysplasia, cancers, and Alzheimer's disease.

Involvement of afadin in barrier function and homeostasis of mouse intestinal epithelia

Afadin interacts with the cytoplasmic region of nectins, which are immunoglobulin-like cell adhesion molecules at adherens junctions, and links them to the actin cytoskeleton. Afadin regulates activities of cells in culture such as directional motility, proliferation and survival. We used Cre-loxP technology to generate mice conditionally lacking afadin specifically in the intestinal epithelia after birth. The loss of afadin caused increased paracellular permeability in the intestinal mucosa and enhanced susceptibility to the tissue destruction induced by dextran sulfate sodium. The junctional architecture of the intestinal epithelia appeared to be preserved, whereas the deficiency of afadin caused the mislocalization of nectin-2 and nectin-3 from adherens junctions to basolateral membrane domains but not that of other components of apical junctions. By contrast, such phenotypic changes were undetected in mice lacking nectin-2, nectin-3 or both. These findings suggest that afadin plays crucial roles, independently of the role as the nectin-afadin module, in barrier function and homeostasis of the intestinal epithelia once the epithelial structure has been established.

Hypoexpression and epigenetic regulation of candidate tumor suppressor gene CADM-2 in human prostate cancer

PURPOSE

Cell adhesion molecules (CADM) comprise a newly identified protein family whose functions include cell polarity maintenance and tumor suppression. CADM-1, CADM-3, and CADM-4 have been shown to act as tumor suppressor genes in multiple cancers including prostate cancer. However, CADM-2 expression has not been determined in prostate cancer.

EXPERIMENTAL DESIGN

The CADM-2 gene was cloned and characterized and its expression in human prostatic cell lines and cancer specimens was analyzed by reverse transcription-PCR and an immunohistochemical tissue array, respectively. The effects of adenovirus-mediated CADM-2 expression on prostate cancer cells were also investigated. CADM-2 promoter methylation was evaluated by bisulfite sequencing and methylation-specific PCR.

RESULTS

We report the initial characterization of CADM-2 isoforms: CADM-2a and CADM-2b, each with separate promoters, in human chromosome 3p12.1. Prostate cancer cell lines, LNCaP and DU145, expressed negligible CADM-2a relative to primary prostate tissue and cell lines, RWPE-1 and PPC-1, whereas expression of CADM-2b was maintained. Using immunohistochemistry, tissue array results from clinical specimens showed statistically significant decreased expression in prostate carcinoma compared with normal donor prostate, benign prostatic hyperplasia, prostatic intraepithelial neoplasia, and normal tissue adjacent to tumor (P < 0.001). Adenovirus-mediated CADM-2a expression suppressed DU145 cell proliferation in vitro and colony formation in soft agar. The decrease in CADM-2a mRNA in cancer cell lines correlated with promoter region hypermethylation as determined by bisulfite sequencing and methylation-specific PCR. Accordingly, treatment of cells with the demethylating agent 5-aza-2'-deoxycytidine alone or in combination with the histone deacetylase inhibitor trichostatin A resulted in the reactivation of CADM-2a expression.

CONCLUSIONS

CADM-2a protein expression is significantly reduced in prostate cancer. Its expression is regulated in part by promoter methylation and implicates CADM-2 as a previously unrecognized tumor suppressor gene in a proportion of human prostate cancers.

[Nectin and nectin-like molecules as markers, actors and targets in cancer]

Nectin and nectin-like (necl) proteins form a family of 9 adhesion molecules that belong to the immunoglobulin superfamily. They play a key role in different biological processes such as cell polarity, proliferation, differentiation and migration in epithelial, endothelial, immune and nervous systems. Besides their role in physiology, they have been involved in different pathological processes in humans. They serve as virus receptors (poliovirus and herpes simplex virus), they are involved in orofacial malformation (CLPED1) and recently they have been described as markers, actors and potential therapeutics targets in cancer. Among them, necl-5, nectin-2 and nectin-4 are overexpressed in tumors, and are associated with a poor prognosis. On the opposite, necl-1, necl-2 and necl-4 act as tumor suppressors and are repressed in cancer. The involvement of nectins and necls molecules in cancer and their potential used in therapy is discussed in this review.

Neoplastic stem cells: current concepts and clinical perspectives

Neoplastic stem cells have initially been characterized in myeloid leukemias where NOD/SCID mouse-repopulating progenitors supposedly reside within a CD34+/Lin- subset of the malignant clone. These progenitors are considered to be self-renewing cells responsible for the in vivo long-term growth of neoplastic cells in leukemic patients. Therefore, these cells represent an attractive target of therapy. In some lymphoid leukemias, NOD/SCID mouse-repopulating cells were also reported to reside within the CD34+/Lin- subfraction of the clone. More recently, several attempts have been made to transfer the cancer stem cell concept to solid tumors and other non-hematopoietic neoplasms. In several of these tumors, the cell surface antigens AC133 (CD133) and CD44 are considered to indicate the potential of a cell to initiate permanent tumor formation in vivo. However, several questions concerning the phenotype, self-renewal capacity, stroma-dependence, and other properties of cancer- or leukemia-initiating cells remain to be solved. The current article provides a summary of our current knowledge on neoplastic (cancer) stem cells, with special emphasis on clinical implications and therapeutic options as well as a discussion about conceptual and technical limitations.