Increased expression of delta-catenin/neural plakophilin-related armadillo protein is associated with the down-regulation and redistribution of E-cadherin and p120ctn in human prostate cancer

GSK-3 phosphorylates delta-catenin and negatively regulates its stability via ubiquitination/proteosome-mediated proteolysis

Delta-catenin was first identified because of its interaction with presenilin-1, and its aberrant expression has been reported in various human tumors and in patients with Cri-du-Chat syndrome, a form of mental retardation. However, the mechanism whereby delta-catenin is regulated in cells has not been fully elucidated. We investigated the possibility that glycogen-synthase kinase-3 (GSK-3) phosphorylates delta-catenin and thus affects its stability. Initially, we found that the level of delta-catenin was greater and the half-life of delta-catenin was longer in GSK-3beta(-/-) fibroblasts than those in GSK-3beta(+/+) fibroblasts. Furthermore, four different approaches designed to specifically inhibit GSK-3 activity, i.e. GSK-3-specific chemical inhibitors, Wnt-3a conditioned media, small interfering RNAs, and GSK-3alpha and -3beta kinase dead constructs, consistently showed that the levels of endogenous delta-catenin in CWR22Rv-1 prostate carcinoma cells and primary cortical neurons were increased by inhibiting GSK-3 activity. In addition, it was found that both GSK-3alpha and -3beta interact with and phosphorylate delta-catenin. The phosphorylation of DeltaC207-delta-catenin (lacking 207 C-terminal residues) and T1078A delta-catenin by GSK-3 was noticeably reduced compared with that of wild type delta-catenin, and the data from liquid chromatography-tandem mass spectrometry analyses suggest that the Thr(1078) residue of delta-catenin is one of the GSK-3 phosphorylation sites. Treatment with MG132 or ALLN, specific inhibitors of proteosome-dependent proteolysis, increased delta-catenin levels and caused an accumulation of ubiquitinated delta-catenin. It was also found that GSK-3 triggers the ubiquitination of delta-catenin. These results suggest that GSK-3 interacts with and phosphorylates delta-catenin and thereby negatively affects its stability by enabling its ubiquitination/proteosome-mediated proteolysis.

Rapid Molecular and Morphological Responses of Prostate Cell Lines to Cell–Cell Contact

Cell-cell adhesion in 2-D PZ-HPV-7 prostate epithelial and DU-145 prostate cancer cell aggregates (monolayers), synchronously and rapidly (within 30 s) formed in suspension in an ultrasound trap has been examined over 60 min. The intracellular distributions of the cadherin/catenin complex components for both cell lines were time-dependent and were clearly identifiable as early as 150 s following cell-cell contact in the trap, while equilibrium positions were reached within 60 min following cell-cell contact. The accumulation of E-cadherin at the cell-cell interface was greater for PZ-HPV-7 than for DU-145 cells over 60 min in the trap, with the apparent formation of adherens junctions over that time scale in PZ-HPV-7 but not in DU-145 cells. The amounts of F-actin, alpha-, beta-, and gamma-catenins recruited to the cell-cell interface of PZ-HPV-7 cells were on average 2.4 times higher than those of DU-145 cells. The ability of different cell types to spread along neighboring cells was 1.5-fold greater for the PZ-HPV-7 than for the DU-145 cells. These results, discussed also in the context of earlier studies of cell adhesion in an ultrasound trap, characterize a reduced adhesiveness of DU-145 cells compared to PZ-HPV-7 cells.

Genomic and expression profiling of adrenocortical carcinoma: application to diagnosis, prognosis and treatment

Adrenocortical carcinoma (ACC) is an aggressive endocrine tumor with a poor 5-year survival rate of 10–20%. Current therapy is often ineffective and may be associated with intolerable side effects. Although ACC is extremely rare, recent advances in genomic and expression profiling, coupled with knowledge gained from the study of the inherited syndromes that increase ACC risk, are beginning to bring together a picture of a tumor type dependent on p53, the G2/M cell cycle transition and IGF2 stimulation. Nevertheless, ACC remains a heterogeneous disease. Only recently have sufficient tumors been characterized and results published to permit an exploration of this diversity. Advances in treatment will depend on exploiting those pathways already implicated in ACC, along with those yet to be identified, and testing those treatments in better models of the disease than the three cell lines that currently exist and are widely available to the community.

delta-Catenin promotes prostate cancer cell growth and progression by altering cell cycle and survival gene profiles

Background

δ-Catenin is a unique member of β-catenin/armadillo domain superfamily proteins and its primary expression is restricted to the brain. However, δ-catenin is upregulated in human prostatic adenocarcinomas, although the effects of δ-catenin overexpression in prostate cancer are unclear. We hypothesized that δ-catenin plays a direct role in prostate cancer progression by altering gene profiles of cell cycle regulation and cell survival.

Results

We employed gene transfection and small interfering RNA to demonstrate that increased δ-catenin expression promoted, whereas its knockdown suppressed prostate cancer cell viability. δ-Catenin promoted prostate cancer cell colony formation in soft agar as well as tumor xenograft growth in nude mice. Deletion of either the amino-terminal or carboxyl-terminal sequences outside the armadillo domains abolished the tumor promoting effects of δ-catenin. Quantitative RT² Profiler™ PCR Arrays demonstrated gene alterations involved in cell cycle and survival regulation. δ-Catenin overexpression upregulated cyclin D1 and cdc34, increased phosphorylated histone-H3, and promoted the entry of mitosis. In addition, δ-catenin overexpression resulted in increased expression of cell survival genes Bcl-2 and survivin while reducing the cell cycle inhibitor p21^Cip1.

Conclusion

Taken together, our studies suggest that at least one consequence of an increased expression of δ-catenin in human prostate cancer is the alteration of cell cycle and survival gene profiles, thereby promoting tumor progression.

Identification of extracellular delta-catenin accumulation for prostate cancer detection

BACKGROUND

Prostate cancer is the second leading cause of cancer death in men, and early detection is essential to reduce mortality and increase survival. delta-Catenin is a unique beta-catenin superfamily protein primarily expressed in the brain but is upregulated in human prostatic adenocarcinomas. Despite its close correlation with the disease, it is unclear whether delta-catenin presents the potential in prostate cancer screening because it is an intracellular protein. In this study, we investigated the hypothesis of delta-catenin accumulation in the urine of prostate cancer patients and its potential pathways of excretion into extracellular milieu.

METHODS

Prostate cancer cell cultures, human tissue biopsies, and voided urines were characterized to determine extracellular delta-catenin accumulation and co-isolation with exosomes/prostasomes.

RESULTS

We identified delta-catenin in culture media and in the stroma of human prostate cancer tissues. In PC-3 cells in culture, delta-catenin was partially co-localized and co-isolated with raft-associated membrane protein caveolin-1 and glycosylphosphatidylinositol-anchored protein CD59, suggesting its potential excretion into extracellular milieu through exosome/prostasome associated pathways. Interference with endocytic pathway using wortmannin did not block prostasome excretion, but delta-catenin overexpression promoted the extracellular accumulation of caveolin-1. delta-Catenin, caveolin-1, and CD59 were all detected in cell-free human voided urine prostasomes. delta-Catenin immunoreactivity was significantly increased in the urine of prostate cancer patients (P < 0.0005).

CONCLUSIONS

This study demonstrated, for the first time, the extracellular accumulation of delta-catenin in urine supporting its potential utility for non-invasive prostate cancer detection.

Increased nucleotide polymorphic changes in the 5'-untranslated region of delta-catenin (CTNND2) gene in prostate cancer

Cancer pathogenesis involves multiple genetic and epigenetic alterations, which result in oncogenic changes in gene expression. delta-Catenin (CTNND2) is overexpressed in cancer, although the mechanisms of its upregulation are highly variable. Here we report that in prostate cancer, the methylation of CpG islands in the delta-catenin promoter was not a primary regulatory event. There was also no delta-catenin gene amplification. However, using the single-strand conformation polymorphism analysis, we observed the increased nucleotide changes in the 5'-untranslated region of delta-catenin gene in human prostate cancer. At least one such change (-9 G>A) is a true somatic point mutation associated with a high Gleason's score, poorly differentiated prostatic adenocarcinoma. Laser capture microdissection coupled with PCR analyses detected the mutation only in cancerous but not in the adjacent benign prostatic tissues. Using chimeric genes encoding the luciferase reporter, we found that this mutation, but not a random mutation or a mutation that disrupts an upstream open reading frame, resulted in a remarkably higher expression and enzyme activity. This mutation did not affect transcriptional efficiency, suggesting that it promotes delta-catenin translation. This is the first report of delta-catenin gene mutation in cancer and supports the notion that multiple mechanisms contribute to its increased expression in carcinogenesis.

E-Cadherin negatively modulates delta-catenin-induced morphological changes and RhoA activity reduction by competing with p190RhoGEF for delta-catenin

delta-Catenin is a member of the p120-catenin subfamily of armadillo proteins. Here, we describe distinctive features of delta-catenin localization and its association with E-cadherin in HEK293 epithelial cells. In HEK293 cells maintained in low cell densities, approximately 15% of cells overexpressing delta-catenin showed dendrite-like process formation, but there was no detectable change in RhoA activity. In addition, delta-catenin was localized mainly in the cytoplasm and was associated with p190RhoGEF. However, at high cell densities, delta-catenin localization was shifted to the plasma membrane. The association of delta-catenin with E-cadherin was strengthened, whereas its interaction with p190RhoGEF was weakened. In mouse embryonic fibroblast cell, ectopic expression of E-cadherin decreased the effect of delta-catenin on the reduction of RhoA activity as well as on dendrite-like process formation. These results suggest that delta-catenin is more dominantly bound to E-cadherin than to p190RhoGEF, and that delta-catenin's function is dependent on its cellular binding partner.

Activating NK cell receptor ligands are differentially expressed during progression to cervical cancer

Human papillomavirus-induced cervical carcinomas often show impaired expression of MHC class I molecules resulting in the inability of tumor cells to directly present viral peptides to cytotoxic T lymphocytes. Loss of MHC class I expression combined with the expression of activating NK cell receptor ligands renders tumor cells potentially susceptible to NK cell attack. Thus, in this study, we analyzed the expression of activating NK cell receptor ligands, NK cell accumulation and activation status in situ in normal ectocervical tissue (NCT), cervical intraepithelial neoplasia (CIN) and squamous cervical carcinoma (CxCa). We observed that expression of the DNAM-1 ligand CD155 was frequently upregulated in CxCa, but not in CIN. The NKG2D ligand MICA was upregulated in fewer CxCa biopsies. In contrast, another NKG2D ligand ULBP2 was preferentially expressed in differentiated epithelial cells of NCT. Increased numbers of NK cells were detected in CIN as compared to NCT and CxCa. Expression of activating NK cell receptor ligands combined with loss of MHC class I was not correlated with enhanced NK cell accumulation or activation status. Furthermore, we demonstrate that cervical cancer cell lines are killed by the NK cell line, NKL, in a NKG2D- and DNAM-1-dependent manner in vitro. Since a significant number of CxCa biopsies showed low MHC class I expression combined with high expression of one or more of the tested activating NK cell receptor ligands, we conclude that CxCa might be a promising target for NK cell-based adoptive immunotherapy.

A delta-catenin signaling pathway leading to dendritic protrusions

Delta-catenin is a synaptic adherens junction protein pivotally positioned to serve as a signaling sensor and integrator. Expression of delta-catenin induces filopodia-like protrusions in neurons. Here we show that the small GTPases of the Rho family act coordinately as downstream effectors of delta-catenin. A dominant negative Rac prevented delta-catenin-induced protrusions, and Cdc42 activity was dramatically increased by delta-catenin expression. A kinase dead LIMK (LIM kinase) and a mutant Cofilin also prevented delta-catenin-induced protrusions. To link the effects of delta-catenin to a physiological pathway, we noted that (S)-3,5-dihydroxyphenylglycine (DHPG) activation of metabotropic glutamate receptors induced dendritic protrusions that are very similar to those induced by delta-catenin. Furthermore, delta-catenin RNA-mediated interference can block the induction of dendritic protrusions by DHPG. Interestingly, DHPG dissociated PSD-95 and N-cadherin from the delta-catenin complex, increased the association of delta-catenin with Cortactin, and induced the phosphorylation of delta-catenin within the sites that bind to these protein partners.

Functional copy-number alterations in cancer

Understanding the molecular basis of cancer requires characterization of its genetic defects. DNA microarray technologies can provide detailed raw data about chromosomal aberrations in tumor samples. Computational analysis is needed (1) to deduce from raw array data actual amplification or deletion events for chromosomal fragments and (2) to distinguish causal chromosomal alterations from functionally neutral ones. We present a comprehensive computational approach, RAE, designed to robustly map chromosomal alterations in tumor samples and assess their functional importance in cancer. To demonstrate the methodology, we experimentally profile copy number changes in a clinically aggressive subtype of soft-tissue sarcoma, pleomorphic liposarcoma, and computationally derive a portrait of candidate oncogenic alterations and their target genes. Many affected genes are known to be involved in sarcomagenesis; others are novel, including mediators of adipocyte differentiation, and may include valuable therapeutic targets. Taken together, we present a statistically robust methodology applicable to high-resolution genomic data to assess the extent and function of copy-number alterations in cancer.

A switch from E-cadherin to N-cadherin expression indicates epithelial to mesenchymal transition and is of strong and independent importance for the progress of prostate cancer

PURPOSE

Cell adhesion molecules are of crucial importance in cancer invasion and metastasis. Epithelial to mesenchymal transition, characterized by reduced E-cadherin and increased N-cadherin expression, has been recognized as a feature of aggressive tumors, but the importance of this phenotype has not been settled in human prostate cancer. We here present novel data, with special focus on the independent relationship between an E-cadherin to N-cadherin switch (EN-switch) and patient prognosis.

EXPERIMENTAL DESIGN

Tissue microarray sections from a consecutive series of 104 radical prostatectomies during 1988 to 1994 with detailed clinicopathologic data and long follow-up were studied immunohistochemically for the expression of E-cadherin, N-cadherin, P-cadherin, beta-catenin, and p120(CTN).

RESULTS

Low E-cadherin expression was significantly associated with adverse clinicopathologic features, whereas other biomarkers were mostly related to Gleason score. In univariate survival analyses, cadherin switching (high N-cadherin and low E-cadherin) showed strong and significant associations with multiple end points of progression and cancer-specific death. Expression of the "basal cell marker" P-cadherin was associated with shorter time to skeletal metastasis (P = 0.036). In multivariate analysis of time to clinical recurrence, the "EN-switch" (hazard ratio, 4.3; P < 0.0005) had strong and independent prognostic effect, together with Gleason score.

CONCLUSION

These novel data unravel the importance of epithelial to mesenchymal transition for prostate cancer progression, and demonstration of a switch from E-cadherin to N-cadherin expression could have significant effect on the care of prostate cancer patients.

Identification of E2F1 as a positive transcriptional regulator for delta-catenin

delta-Catenin is upregulated in human carcinomas. However, little is known about the potential transcriptional factors that regulate delta-catenin expression in cancer. Using a human delta-catenin reporter system, we have screened several nuclear signaling modulators to test whether they can affect delta-catenin transcription. Among beta-catenin/LEF-1, Notch1, and E2F1, E2F1 dramatically increased delta-catenin-luciferase activities while beta-catenin/LEF-1 induced only a marginal increase. Rb suppressed the upregulation of delta-catenin-luciferase activities induced by E2F1 but did not interact with delta-catenin. RT-PCR and Western blot analyses in 4 different prostate cancer cell lines revealed that regulation of delta-catenin expression is controlled mainly at the transcriptional level. Interestingly, the effects of E2F1 on delta-catenin expression were observed only in human cancer cells expressing abundant endogenous delta-catenin. These studies identify E2F1 as a positive transcriptional regulator for delta-catenin, but further suggest the presence of strong negative regulator(s) for delta-catenin in prostate cancer cells with minimal endogenous delta-catenin expression.

The role of tissue microarrays in prostate cancer biomarker discovery

Tissue microarrays (TMAs) offer the potential to rapidly translate genomics and basic science research findings to practical clinical application. This is particularly true in the field of cancer biomarker research, where TMAs can be used for candidate biomarker validation and association with patient clinical, pathologic, and outcomes parameters. In this review, we examine the effect of TMA use on prostate cancer biomarker research, focusing on the types of TMAs that have been used, and the biomarkers that have been examined. The results demonstrate that TMAs have been very effective in screening candidate biomarkers for subsequent, extended evaluation in large patient populations. In addition, the use of TMAs in multiple biomarker series allows for the statistical analysis of sets of biomarkers as diagnostic or prognostic tests. The processes used here can be applied to any tumor type to improve patient diagnosis, prognosis, and treatment response prediction.

Altered E-cadherin expression and p120 catenin localization in esophageal squamous cell carcinoma

BACKGROUND

E-cadherin is a well-known tumor suppressor and its dysregulated expression correlates with tumor differentiation, metastasis and survival in esophageal squamous cell carcinoma (ESCC). p120 catenin is an Armadillo protein normally bound to E-cadherin in the cadherin-catenin complex at the adherens junction. Dysregulated expression and mislocalization of p120ctn affect the protective function of the complex. The objective of the present study was to evaluate the clinical significance of E-cadherin and p120ctn expression in ESCC.

METHODS

Immunohistochemistry was performed to investigate the expression of E-cadherin and p120ctn proteins in 71 patients with ESCC. The relationships between protein expression and clinicopathological characteristics were analyzed.

RESULTS

Reduced E-cadherin and p120ctn expressions were observed in 42.3% and 8.5% of ESCC cases, respectively. Reduction of membranous p120ctn was observed in 33.8% of cases. Membranous E-cadherin was preserved when p120ctn co-localized on the membrane of tumor cells (72.3%, P = 0.001). High level E-cadherin expression and membranous p120ctn preservation positively correlated with tumor differentiation (P = 0.001 and P = 0.008, respectively). p120ctn expression was also significantly related to lymph node metastasis (P = 0.003). Heterogeneous expression of both E-cadherin and p120ctn was observed in dysplasia.

CONCLUSIONS

Altered E-cadherin expression and p120ctn localization were related to tumor differentiation, indicating their important roles in the pathogenesis of ESCC.

Diverse functions of p120ctn in tumors

p120ctn is a member of the Armadillo protein family. It stabilizes the cadherin-catenin adhesion complex at the plasma membrane, but also has additional roles in the cytoplasm and nucleus. Extensive alternative mRNA splicing and multiple phosphorylation sites generate additional complexity. Evidence is emerging that complete loss, downregulation or mislocalization of p120ctn correlates with progression of different types of human tumors. It remains to be determined whether a causal relationship exists between specific isoform expression, subcellular localization or selective phosphorylation of p120ctn on the one hand and tumor prognosis on the other.

Developmental functions of the P120-catenin sub-family

For more than a decade, cell, developmental and cancer investigators have brought about a wide interest in the biology of catenin proteins, an attraction being their varied functions within differing cellular compartments. While the diversity of catenin localizations and roles has been intriguing, it has also posed a challenge to the clear interpretation of loss- or gain-of-function developmental phenotypes. The most deeply studied member of the larger catenin family is beta-catenin, whose contributions span areas including cell adhesion and intracellular signaling/ transcriptional control. More recently, attention has been directed towards p120-catenin, which in conjunction with the p120-catenin sub-family members ARVCF- and delta-catenins, are the subjects of this review. Although the requirement for vertebrate versus invertebrate p120-catenin are at variance, vertebrate p120-catenin sub-family members may each inter-link cadherin, cytoskeletal and gene regulatory functions in embryogenesis and disease.