Truncated DCC reduces N-cadherin/catenin expression and calcium-dependent cell adhesion in neuroblastoma cells

Cell Adhesion Molecules in Neuroblastoma: Complex Roles, Therapeutic Potential

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

De Novo Pathogenic Variants in N-cadherin Cause a Syndromic Neurodevelopmental Disorder with Corpus Collosum, Axon, Cardiac, Ocular, and Genital Defects

Cadherins constitute a family of transmembrane proteins that mediate calcium-dependent cell-cell adhesion. The extracellular domain of cadherins consists of extracellular cadherin (EC) domains, separated by calcium binding sites. The EC interacts with other cadherin molecules in cis and in trans to mechanically hold apposing cell surfaces together. CDH2 encodes N-cadherin, whose essential roles in neural development include neuronal migration and axon pathfinding. However, CDH2 has not yet been linked to a Mendelian neurodevelopmental disorder. Here, we report de novo heterozygous pathogenic variants (seven missense, two frameshift) in CDH2 in nine individuals with a syndromic neurodevelopmental disorder characterized by global developmental delay and/or intellectual disability, variable axon pathfinding defects (corpus callosum agenesis or hypoplasia, mirror movements, Duane anomaly), and ocular, cardiac, and genital anomalies. All seven missense variants (c.1057G>A [p.Asp353Asn]; c.1789G>A [p.Asp597Asn]; c.1789G>T [p.Asp597Tyr]; c.1802A>C [p.Asn601Thr]; c.1839C>G [p.Cys613Trp]; c.1880A>G [p.Asp627Gly]; c.2027A>G [p.Tyr676Cys]) result in substitution of highly conserved residues, and six of seven cluster within EC domains 4 and 5. Four of the substitutions affect the calcium-binding site in the EC4-EC5 interdomain. We show that cells expressing these variants in the EC4-EC5 domains have a defect in cell-cell adhesion; this defect includes impaired binding in trans with N-cadherin-WT expressed on apposing cells. The two frameshift variants (c.2563_2564delCT [p.Leu855Valfs^∗4]; c.2564_2567dupTGTT [p.Leu856Phefs^∗5]) are predicted to lead to a truncated cytoplasmic domain. Our study demonstrates that de novo heterozygous variants in CDH2 impair the adhesive activity of N-cadherin, resulting in a multisystemic developmental disorder, that could be named ACOG syndrome (agenesis of corpus callosum, axon pathfinding, cardiac, ocular, and genital defects).

Epithelial-mesenchymal transition promotes SOX2 and NANOG expression in bladder cancer

Bladder cancer is the most common malignant tumor of the urothelium and is classified into non-muscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC). Stemness markers such as SOX2 and NANOG are frequently overexpressed in various aggressive cancers, including MIBC; epithelial-mesenchymal transition (EMT) has been proposed as a potential trigger of stemness in cancers. To determine whether cancer stemness is acquired via EMT in bladder cancer, we studied the effect of EMT on the expression of SOX2 and NANOG in bladder cancer cell lines. We also analyzed their expression in clinical tissue samples. Our results revealed that a potent EMT inducer (transforming growth factor β1) reduced the expression of the epithelial marker E-cadherin and increased expression of both SOX2 and NANOG in epithelial-type bladder cancer cells. As for clinical bladder cancer samples, in NMIBC, E-cadherin expression was slightly diminished, and the expression of both SOX2 and NANOG was negligible. In contrast, in MIBC, E-cadherin expression was highly and heterogeneously diminished, while the expression of both SOX2 and NANOG was increased. We also noticed that either E-cadherin or SOX2 (or NANOG) was expressed (ie, in a manner exclusive of each other). In addition, the concentration of E-cadherin showed a significant negative correlation with tumor grade and stage, while expression of SOX2 and NANOG positively correlated with those clinicopathological parameters. These findings suggest that EMT promotes stemness of bladder cancer cells, contributing to tumor aggressiveness. This EMT-cancer stemness axis may also play an important role in the pathogenesis of NMIBC and MIBC.Laboratory Investigation advance online publication, 27 February 2017; doi:10.1038/labinvest.2017.17.

PKC inhibition increases gap junction intercellular communication and cell adhesion in human neuroblastoma

Gap junction intercellular communication and cell-cell adhesion are essential for maintaining a normal cellular phenotype, including the control of growth and proliferation. Loss of either cell-cell adhesion or communication is common in cancers, while restoration of function is associated with tumor suppression. Protein kinase C (PKC) isozymes regulate a broad spectrum of cellular functions including growth and proliferation, and their overexpression has been correlated with carcinogenesis. Consequently, PKC inhibitors are currently undergoing clinical trials as an anti-cancer agents although the precise cellular alterations induced by PKC inhibitors remain to be elucidated. In the current study, the effects of PKC inhibitors on cell interactions were investigated using human neuroblastoma (IMR32, SKNMC, and SHSY-5Y) cell lines. An analysis of intercellular communication revealed an increase in gap junctional coupling with PKC inhibition. The observed increase in coupling was not associated with a change in Connexin 43 distribution or an alteration of phosphorylation status of the protein. There was also an increase in cell-cell adhesion with PKC inhibitor treatment as indicated by a cell aggregation assay. Therefore, the growth suppressive abilities of PKC inhibition on tumors may be due to the cancer suppressive effects of increased gap junction intercellular communication and cell-cell adhesion.

Prognostic significance of cadherin-based adhesion molecules in cutaneous malignant melanoma

BACKGROUND

The need for novel molecular prognostic markers that can supplement validated clinicopathologic correlates for cutaneous malignant melanoma is well recognized. Proteins that mediate the epithelial-mesenchymal transition, the process by which a cancer cell disengages from its parent tumor, are important candidates.

METHODS

The prognostic relevance of E-cadherin, N-cadherin, and P-cadherin, calcium-dependent transmembrane glycoproteins that regulate cell-cell adhesion, and their adaptors, alpha-catenin, beta-catenin, and p120-catenin, was evaluated on a cohort of 201 primary and 274 metastatic melanoma tumors using fluorescence-based immunohistochemical methods and Automated Quantitative Analysis of protein expression on digitally captured photomicrographs.

RESULTS

Increasing levels of N-cadherin expression improved overall survival (log-rank = 7.31; P = 0.03) but did not retain significance following adjustment for established clinicopathologic correlates (P = 0.50). Higher levels of E-cadherin approached significance for favorable prognosis on both univariate (P = 0.13) and multivariable (P = 0.10) analyses. Hierarchical clustering of the composite profiles for all six markers identified four unique clusters that yielded differential overall survival (log-rank = 10.54; P = 0.01). Cluster 4, expressing high E-cadherin and N-cadherin levels, possessed the most favorable outcome and cluster 2, featuring low E-cadherin and alpha-catenin but modest N-cadherin, showed least favorable outcomes. Cluster 2 remained significant on multivariable analysis (hazard ratio, 3.29; 95% confidence interval, 1.50-7.19; P = 0.003).

CONCLUSIONS

Although none of the cadherin-based adhesion molecules were independently prognostic, multimarker profiles were significant. Similar to epithelial-derived tumors, loss of E-cadherin correlates with poor outcome. In contrast, for neural crest-derived cutaneous malignant melanoma, N-cadherin overexpression can be associated with either a successful epithelial-mesenchymal transition or a favorably differentiated tumor. Additional cadherin profiles are needed to discriminate these distinctive phenotypes.

Automated quantitative analysis of DCC tumor suppressor protein in ovarian cancer tissue microarray shows association with β-catenin levels and outcome in patients with epithelial ovarian cancer

BACKGROUND

The deleted in colorectal cancer (DCC) protein, the product of DCC tumor suppressor gene, is frequently altered in cancer. Preclinical data demonstrate that DCC regulates beta-catenin levels. Here, we sought to determine the association of DCC with beta-catenin protein levels, clinicopathological parameters and patient outcome in ovarian cancer using a method of in situ compartmentalized protein analysis.

METHODS

A tissue array composed of 150 advanced-stage ovarian cancers, treated with surgical debulking and platinum-paclitaxel (Taxol) combination chemotherapy, was constructed. For evaluation of protein expression, we used an immunofluorescence-based method of automated in situ quantitative measurement of protein analysis (AQUA).

RESULTS

One hundred and twelve patients (74%) had sufficient tissue for AQUA. The median follow-up time for the entire cohort was 33 months. Patients with low nuclear DCC expression had a 3-year progression-free survival (PFS) rate of 0% compared with 33% of those with high DCC expression (P = 0.0067). In multivariate analysis, low nuclear DCC expression level retained its prognostic significance for PFS. Between DCC and beta-catenin, a significant relationship was found, where tumors with low DCC had low beta-catenin and vice versa (P = 0.003).

CONCLUSIONS

Low nuclear DCC levels predict for poor patient outcome in epithelial ovarian cancer. DCC may exert its antitumor function, in part, through regulation of beta-catenin levels.

Multiple intracranial seeding of craniopharyngioma after repeated surgery--case report

A 17-year-old woman presented with a rare case of intracranial seeding of craniopharyngioma after repeated surgery. She initially presented with secondary amenorrhea and visual impairment. Magnetic resonance imaging revealed a suprasellar mass. Subtotal removal of the tumor was performed. The diagnosis was adamantinomatous craniopharyngioma. Seven months later, the patient underwent a second operation for recurrence of the craniopharyngioma. Subsequently, ventriculoperitoneal (VP) shunting and gamma knife surgery were performed. Twenty-seven months after the first operation, multiple cystic lesions were found in the right frontal and temporal lobes. Positive tumor cytology was observed in the cerebrospinal fluid obtained from the VP shunt chamber. These tumors were subtotally resected. However, the patient died from consecutive tumor recurrence 4 years after the initial diagnosis.