δ-Catenin Increases the Stability of EGFR by Decreasing c-Cbl Interaction and Enhances EGFR/Erk1/2 Signaling in Prostate Cancer

δ-Catenin, a member of the p120-catenin subfamily of armadillo proteins, reportedly increases during the late stage of prostate cancer. Our previous study demonstrates that δ-catenin increases the stability of EGFR in prostate cancer cell lines. However, the molecular mechanism behind δ-catenin-mediated enhanced stability of EGFR was not explored. In this study, we hypothesized that δ-catenin enhances the protein stability of EGFR by inhibiting its lysosomal degradation that is mediated by c-casitas b-lineage lymphoma (c-Cbl), a RING domain E3 ligase. c-Cbl monoubiquitinates EGFR and thus facilitates its internalization, followed by lysosomal degradation. We observed that δ-catenin plays a key role in EGFR stability and downstream signaling. δ-Catenin competes with c-Cbl for EGFR binding, which results in a reduction of binding between c-Cbl and EGFR and thus decreases the ubiquitination of EGFR. This in turn increases the expression of membrane bound EGFR and enhances EGFR/Erk1/2 signaling. Our findings add a new perspective on the role of δ-catenin in enhancing EGFR/Erk1/2 signaling-mediated prostate cancer.

p120 Catenin-Mediated Stabilization of E-Cadherin Is Essential for Primitive Endoderm Specification

E-cadherin-mediated cell-cell adhesion is critical for naive pluripotency of cultured mouse embryonic stem cells (mESCs). E-cadherin-depleted mESC fail to downregulate their pluripotency program and are unable to initiate lineage commitment. To further explore the roles of cell adhesion molecules during mESC differentiation, we focused on p120 catenin (p120ctn). Although one key function of p120ctn is to stabilize and regulate cadherin-mediated cell-cell adhesion, it has many additional functions, including regulation of transcription and Rho GTPase activity. Here, we investigated the role of mouse p120ctn in early embryogenesis, mESC pluripotency and early fate determination. In contrast to the E-cadherin-null phenotype, p120ctn-null mESCs remained pluripotent, but their in vitro differentiation was incomplete. In particular, they failed to form cystic embryoid bodies and showed defects in primitive endoderm formation. To pinpoint the underlying mechanism, we undertook a structure-function approach. Rescue of p120ctn-null mESCs with different p120ctn wild-type and mutant expression constructs revealed that the long N-terminal domain of p120ctn and its regulatory domain for RhoA were dispensable, whereas its armadillo domain and interaction with E-cadherin were crucial for primitive endoderm formation. We conclude that p120ctn is not only an adaptor and regulator of E-cadherin, but is also indispensable for proper lineage commitment.

Characterization of α-, β- and p120-Catenin Expression in Feline Mammary Tissues and their Relation with E- and P-Cadherin

BACKGROUND

Abnormal catenin expression has been related to mammary carcinogenesis in both human and canine species and they are considered tumor- and invasion-suppressor molecules; however, in feline mammary tissues they have been scarcely studied.

MATERIALS AND METHODS

The immunohistochemical expression of α-, β- and p120-catenin was studied in a series of normal feline mammary glands, hyperplastic/dysplastic lesions and benign and malignant mammary tumors. Their relationship with clinicopathological parameters and with E- and P-cadherin expression was assessed.

RESULTS

Normal tissues, hyperplastic/dysplastic lesions and benign tumors expressed α-, β- and p120-catenin in the membrane of more than 75% of the luminal epithelial cells, while in malignant tumors, there was a reduction in their membranous expression and a p120-catenin cytoplasmic expression in 40%. Reduced α-catenin expression was related to tumor features with prognostic value, namely tumor size (p=0.0203) and necrosis (p=0.0205). The expression of α-, β- and p120-catenin were individually related to each other and collectively associated with E-cadherin expression.

CONCLUSION

The results demonstrate a relationship between feline mammary carcinogenesis and decreased expression of catenins, suggesting that they may represent a valuable tool in the diagnosis of feline mammary neoplasms.

Protective role of p120-catenin in maintaining the integrity of adherens and tight junctions in ventilator-induced lung injury

BACKGROUND

Ventilator-induced lung injury (VILI) is one of the most common complications for patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). Although p120 is an important protein in the regulation of cell junctions, further mechanisms should be explored for prevention and treatment of VILI.

METHODS

Mouse lung epithelial cells (MLE-12), which were transfected with p120 small interfering (si)RNA, p120 cDNA, wild-type E-cadherin juxtamembrane domain or a K83R mutant juxtamembrane domain (K83R-JMD), were subjected to 20% cyclic stretches for 2 or 4 h. Furthermore, MLE-12 cells and mice, which were pretreated with the c-Src inhibitor PP2 or RhoA inhibitor Y27632, underwent 20% cyclic stretches or mechanical stretching, respectively. Moreover, wild-type C57BL/6 mice were transfected with p120 siRNA-liposome complexes before mechanical ventilation. Cell lysates and lung tissues were then analyzed to detect lung injury.

RESULTS

cyclic stretches of 20% actived c-Src, which induced degradation of E-cadherin, p120 and occludin. However, loss of p120 increased the degradation and endocytosis of E-cadherin. Immunoprecipitation and Immunofluorescence results showed a decrease in the association between p120 and E-cadherin, while gap formation increased in p120 siRNA and K83R-JMD groups after 20% cyclic stretches. Loss of p120 also reduced the occludin level and decreased the association of occludin and ZO-1 by enhancing RhoA activity. However, the altered levels of occludin and E-cadherin were reversed by PP2 or Y27632 treatments compared with the cyclic stretch group. Consistently, the expression, redistribution and disassociation of junction proteins were all restored in the p120 overexpression group after 20% cyclic stretches. Moreover, the role of p120 in VILI was confirmed by increased wet/dry weigh ratio and enhanced production of cytokines (tumor necrosis factor-α and interleukin-six) in p120-depleted mice under mechanical ventilation.

CONCLUSIONS

p120 protected against VILI by regulating both adherens and tight junctions. p120 inhibited E-cadherin endocytosis by increasing the association between p120 and juxtamembrane domain of E-cadherin. Furthermore, p120 reduced the degradation of occludin by inhibiting RhoA activity. These findings illustrated further mechanisms of p120 in the prevention of VILI, especially for patients with ALI or ARDS.

Epithelial-mesenchymal transition (EMT) markers have prognostic impact in multiple primary oral squamous cell carcinoma

Multiple primary tumors can occur in up to 35 % of the patients with head and neck cancer, however its clinicopathological features remain controversial. Deregulation of epithelial-mesenchymal transition (EMT) signaling has been associated with aggressive malignancies and tumor progression to metastasis in several cancer types. This study is the first to explore EMT process in multiple primary oral squamous cell carcinomas (OSCC). Immunohistochemical analysis of E-cadherin, catenin (α, β, and γ), APC, collagen IV, Ki-67, cyclin D1, and CD44 were performed in a tissue microarray containing multiple representative areas from 102 OSCC patients followed-up by at least 10 years. Results were analysed in relation to clinicopathological characteristics and survival rates in patients presenting multiple primary tumors versus patients without second primary tumors or metastatic disease. Significant association was observed among multiple OSCCs and protein expression of E-cadherin (P = 0.002), β-catenin (P = 0.047), APC (P = 0.017), and cyclin D1 (P = 0.001) as well as between lymph nodes metastasis and Ki-67 staining (P = 0.021). OSCCs presenting vascular embolization were associated with negative β-catenin membrane expression (P = 0.050). There was a significantly lower survival probability for patients with multiple OSCC (log-rank test, P < 0.0001), for tumors showing negative protein expression for E-cadherin (log-rank test, P = 0.003) and β-catenin (log-rank test, P = 0.031). Stratified multivariate survival analysis revealed a prognostic interdependence of E-cadherin and β-catenin co-downexpression in predicting the worst overall survival (log-rank test, P = 0.007). EMT markers have a predicted value for invasiveness related to multiple primary tumors in OSCC and co-downregulation of E-cadherin and β-catenin has a significant prognostic impact in these cases.

The expression of δ-catenin in esophageal squamous cell carcinoma and its correlations with prognosis of patients

As a member of the catenin family, expression of δ-catenin and its clinical implication in numerous tumors remain unclear. In the present study, expression of δ-catenin in esophageal squamous cell carcinoma (ESCC) and its correlations with patient prognosis were explored. We detected the expression of δ-catenin, by immunohistochemistry, in ESCC tissues from 299 cases and analyzed the correlation between δ-catenin expression and patient clinicopathological features. Compared with a lack of expression in adjacent normal esophageal epithelium (0%, 0/47), the frequency of δ-catenin protein was increased in ESCC tissues to 41.5% (124/299, P < .001) and expression correlated with TNM stage and lymph node metastasis (P = .025 and .019, respectively). Furthermore, Kaplan-Meier survival analysis revealed that patients with high δ-catenin expression had shorter survival than patients with low expression (P = .010), and multivariate Cox analysis revealed that high δ-catenin expression was also an independent prognostic factor (P = .001). In transwell assays, migration of ESCC cells was enhanced by δ-catenin overexpression, whereas proliferation of ESCC cells was unchanged. Together, our results suggest that δ-catenin acts as an oncoprotein when overexpressed in ESCC, and its expression is associated with poor prognosis and malignant cell behavior.

Co-expression of delta-catenin and RhoA is significantly associated with a malignant lung cancer phenotype

Delta-catenin, a member of the p120-catenin subfamily, and the Rho GTPase RhoA both have roles in the regulation of the cytoskeleton. In this study, we found that delta-catenin positive expression and RhoA over-expression is consistently found in non-small cell lung cancer, but not in normal lung tissue, and that their co-expression was significantly associated with histological type, differentiation, pTNM stage, lymphatic metastasis and a poor prognosis. We also demonstrate that delta-catenin can directly interact with RhoA and regulate its activity, which in turn mediates tumor invasion and metastasis.

Cordial connections: molecular ensembles and structures of adhering junctions connecting interstitial cells of cardiac valves in situ and in cell culture

Remarkable efforts have recently been made in the tissue engineering of heart valves to improve the results of valve transplantations and replacements, including the design of artificial valves. However, knowledge of the cell and molecular biology of valves and, specifically, of valvular interstitial cells (VICs) remains limited. Therefore, our aim has been to determine and localize the molecules forming the adhering junctions (AJs) that connect VICs in situ and in cell culture. Using biochemical and immunolocalization methods at the light- and electron-microscopic levels, we have identified, in man, cow, sheep and rat, the components of VIC-connecting AJs in situ and in cell culture. These AJs contain, in addition to the transmembrane glycoproteins N-cadherin and cadherin-11, the typical plaque proteins alpha- and beta-catenin as well as plakoglobin and p120, together with minor amounts of protein p0071, i.e. a total of five plaque proteins of the armadillo family. While we can exclude the occurrence of desmogleins, desmocollins and desmoplakin, we have noted with surprise that AJs of VICs in cell cultures, but not those growing in the valve tissue, contain substantial amounts of the desmosomal plaque protein, plakophilin-2. Clusters of AJs occur not only on the main VIC cell bodies but are also found widely dispersed on their long filopodia thus forming, in the tissue, a meshwork that, together with filopodial attachments to paracrystalline collagen fiber bundles, establishes a three-dimensional suprastructure, the role of which is discussed with respect to valve formation, regeneration and function.

Catenin expression in T1/2 carcinomas of the floor of the mouth

Reduction of the expression of catenin is a crucial step in the pathogenesis, progression and prognosis of many epithelial cancers including squamous cell carcinomas (SCCs). Catenin expression in oral carcinomas was evaluated in relation to clinico-pathological features in order to determine its value as a prognostic marker. Eighty-five patients with histologically proven T1/2 squamous cell carcinoma of the oral floor who underwent surgical treatment were eligible for the study. A tissue microarray consisting of multiple representative tissue cores of each carcinoma was composed. The expression levels of alpha, beta and gamma-catenins were determined immunohistologically. Correlation between clinical features and the expression of catenin proteins was evaluated statistically using Kaplan-Meier curves, log-rank tests and chi(2)-tests. Loss of alpha-catenin expression in carcinoma of the floor of the mouth correlated significantly with poor prognosis (P=0.05). Conversely, significantly reduced rates of lymph-node metastases were observed in alpha- and beta-catenin-positive T1 and T2 SCCs. Loss of gamma-catenin expression indicated a reduced survival rate in nodal-negative tumours (P=0.02). Catenin expression in carcinomas of the floor of the mouth seems to be a predictive parameter in the prognosis of T1 and T2 SSCs.

The green tea compound, (-)-epigallocatechin-3-gallate downregulates N-cadherin and suppresses migration of bladder carcinoma cells

Green tea has been reported as potential dietary protection against numerous cancers and has been shown to have activity in bladder tumor inhibition in different animal models. The goal of this study was to examine the effects of (-)-epigallocatechin gallate (EGCG-the major phytochemical in green tea) on growth inhibition and behavior of human bladder carcinoma cells and to identify the altered signaling pathway(s) underlying the response to EGCG exposure. EGCG inhibited the in vitro growth of invasive bladder carcinoma cells with an IC(50) range of 70-87 microM. At a concentration of 20 microM, EGCG decreased the migratory potential of bladder carcinoma cells with concomitant activation of p42/44 MAPK and STAT3 and inactivation of Akt. Using biochemical inhibitors of MAPK/ERK, and siRNA to knockdown STAT3 and Akt, inhibition of migration was recorded associated with Akt but not MAPK/ERK or STAT3 signaling in bladder cells. In addition, EGCG downregulated N-cadherin in a dose-dependent manner where reduction in N-cadherin expression paralleled declining migratory potential. Continuous feeding of EGCG to mice prior to and during the establishment of bladder carcinoma xenografts in vivo revealed >50% reduction in mean final tumor volume (P </= 0.05) with no detectable toxicity. EGCG inhibited bladder carcinoma cell growth and suppressed the in vitro migration capacity of cells via downregulation of N-cadherin and inactivation of Akt signaling. Continuous administration of EGCG to mice revealed significant inhibition of tumor growth in vivo indicating a possible preventative role for green tea in bladder cancer.

The prognostic value of E-cadherin and the cadherin-associated molecules alpha-, beta-, gamma-catenin and p120ctn in prostate cancer specific survival: a long-term follow-up study

OBJECTIVES

To determine the value of loss of expression of E-cadherin and cadherin associated molecules as prognostic markers for prostate cancer patients in a long-term follow-up study.

METHODS

Sixty-five prostate cancer specimens, obtained from patients with different stages of prostate cancer who underwent a radical prostatectomy or TUR-P between 1987 and 1991, were used for immunohistochemical analysis of the expression pattern of E-cadherin, alpha-, beta-, gamma-catenin and p120(ctn). Clinical records of these patients were studied for follow-up data and the prognostic value of expression of these adhesion molecules was determined by Kaplan-Meier survival analyses and multivariable proportional hazard regression analysis.

RESULTS

Normal staining patterns were found in 36 cases (55.4%) for E-cadherin, 37 cases (56.9%) for alpha-catenin, 40 cases (61.5%) for beta-catenin, 25 cases (38.5%) for gamma-catenin, and 40 cases (61.5%) for p120(ctn). Overall, a strong correlation was found between the expression of E-cadherin and other cadherin-associated molecules. The 5-year survival rates for each staining were as follows: E-cadherin (normal 79.2%, aberrant 26.8%), alpha-catenin (normal 79.2%, aberrant 26.8%), beta-catenin (normal 73.1%, aberrant 27.3%), gamma-catenin (normal 86.4%, aberrant 37.1%), and p120(ctn) (normal 72.8%, aberrant 30.0%). There was a significant difference in survival between normal and aberrant expression in each staining (log rank P < 0.0001). The proportional hazard regression model including tumor stage and Gleason score revealed alpha-catenin expression as the best prognostic marker for patients with prostate cancer.

CONCLUSIONS

Our data revealed a strong correlation between E-cadherin expression and other cadherin-associated molecules. Among these markers, alpha-catenin seems the best prognostic marker for prostate cancer specific survival. Larger studies are needed to confirm this result.

[Expresion of E-cadherin and catenins in urothelial carcinomas]

OBJECTIVE

We examined the presence of E-cadherin and alpha, beta and gamma catenins detected by immunohistochemistry and correlated with the classic variables: grade, stage and recurrence.

MATERIAL AND METHOD

The authors evaluated 37 transitional cell carcinomas. Biopsy specimens included no recurrent transitional cell carcinoma (n=19) and recurrent transitional cell carcinoma (n=18). Association of E-cadherin and alpha, beta and gamma catenins immunoreactivity with tumor grade, clinical stage and tumor recurrence was examined.

RESULTS

E-cadherin and gamma catenin expression were related to the clinical stage of the disease, alpha and beta catenins were not correlated with grade, stage and recurrence of disease.

CONCLUSIONS

Decreased E cadherin and gamma catenin expression were associated with advanced stage of the disease.

Down-regulation of MUC1 in cancer cells inhibits cell migration by promoting E-cadherin/catenin complex formation

MUC1, a tumor associated glycoprotein, is over-expressed in most cancers and can promote proliferation and metastasis. The objective of this research was to study the role of MUC1 in cancer metastasis and its potential mechanism. Pancreatic (PANC1) and breast (MCF-7) cancer cells with stable 'knockdown' of MUC1 expression were created using RNA interference. beta-Catenin and E-cadherin protein expression were upregulated in PANC1 and MCF-7 cells with decreased MUC1 expression. Downregulation of MUC1 expression also induced beta-catenin relocation from the nucleus to the cytoplasm, increased E-cadherin/beta-catenin complex formation and E-cadherin membrane localization in PANC1 cells. PANC1 cells with 'knockdown' MUC1 expression had decreased in vitro cell invasion. This study suggested that MUC1 may affect cancer cell migration by increasing E-cadherin/beta-catenin complex formation and restoring E-cadherin membrane localization.

Overexpression of ICAT highlights a role for catenin-mediated canonical Wnt signalling in early T cell development

Transcription factors of the T cell factor/lymphoid enhancing factor (Tcf/Lef) family are key regulators in the development of T cell precursors to the CD4+8+ stage. These factors are known targets of the canonical Wnt signalling pathway, and regulate transcription of Wnt target genes following interaction with the armadillo repeat-containing protein beta-catenin. However, as recent studies show normal thymocyte maturation in the absence of either beta-catenin or its homologue gamma-catenin, the role of Wnt signalling in Tcf/Lef activation during T cell development is controversial. To directly investigate the importance of catenin-mediated Wnt signalling in early thymocytes, we have compared the expression of beta- and gamma-catenin and analysed distinct stages of T cell precursor maturation following overexpression of inhibitor of beta-catenin and Tcf (ICAT), which inhibits Wnt signalling by preventing binding of armadillo repeat-containing proteins to Tcf/Lef. By direct retroviral gene targeting of CD4-8- and CD4+8+ precursors, we show that ICAT overexpression inhibits the CD4-8--to-CD4+8+ transition, but not the CD4+8+-to-CD4+8- or -CD4-8+ transition. Collectively, our data support a model in which canonical Wnt signalling influences T cell development in the thymus by playing an essential role in the maturation of CD4-8- but not CD4+8+ thymocytes.

Expression pattern of adhesion molecules in junctional epithelium differs from that in other gingival epithelia

BACKGROUND AND OBJECTIVE

The gingival epithelium is the physiologically important interface between the bacterially colonized gingival sulcus and periodontal soft and mineralized connective tissues, requiring protection from exposure to bacteria and their products. However, of the three epithelia comprising the gingival epithelium, the junctional epithelium has much wider intercellular spaces than the sulcular epithelium and oral gingival epithelium. Hence, the aim of the present study was to characterize the cell adhesion structure in the junctional epithelium compared with the other two epithelia.

MATERIAL AND METHODS

Gingival epithelia excised at therapeutic flap surgery from patients with periodontitis were examined for expression of adhesion molecules by immunofluorescence.

RESULTS

In the oral gingival epithelium and sulcular epithelium, but not in the junctional epithelium, desmoglein 1 and 2 in cell-cell contact sites were more abundant in the upper than the suprabasal layers. E-cadherin, the main transmembranous molecule of adherens junctions, was present in spinous layers of the oral gingival epithelium and sulcular epithelium, but was scarce in the junctional epithelium. In contrast, desmoglein 3 and P-cadherin were present in all layers of the junctional epithelium as well as the oral gingival epithelium and sulcular epithelium. Connexin 43 was clearly localized to spinous layers of the oral gingival epithelium, sulcular epithelium and parts of the junctional epithelium. Claudin-1 and occludin were expressed in the cell membranes of a few superficial layers of the oral gingival epithelium.

CONCLUSION

These findings indicated that the junctional epithelium contains only a few desmosomes, composed of only desmoglein 3; adherens junctions are probably absent because of defective E-cadherin. Thus, the anchoring junctions connecting junctional epithelium cells are lax, causing widened intercellular spaces. In contrast, the oral gingival epithelium, which has a few tight junctions, functions as a barrier.

Derangement of the E-cadherin/catenin complex is involved in transformation of differentiated to anaplastic thyroid carcinoma

BACKGROUND

Anaplastic thyroid cancer arises, or transforms, from pre-existing differentiated thyroid cancer. E-cadherin functions as a cell-cell adhesion molecule that complexes with catenin proteins for function. The objective of this study was to evaluate the change in E-cadherin/beta-catenin expression in the transformation of differentiated to anaplastic thyroid carcinoma.

METHODS

A tissue microarray was constructed from 12 anaplastic thyroid tumors and their adjacent associated differentiated foci. Immunohistochemistry was used to evaluate tumor expression of E-cadherin and beta-catenin.

RESULTS

There was decreased expression of E-cadherin and beta-catenin by the anaplastic tumors when compared with the differentiated thyroid tumors from which they evolved. The expression of E-cadherin and beta-catenin was 92% and 67%, respectively, by the differentiated thyroid carcinoma, and 17% and 50%, respectively, by the anaplastic tumors.

CONCLUSIONS

This report shows that derangement of the E-cadherin/catenin complex is associated with the transformation of differentiated into anaplastic thyroid carcinoma.

Cadherins and catenins in clival chordomas: correlation of expression with tumor aggressiveness

The local invasiveness and occasional rapid growth of chordomas, despite optimal treatment, highlight the need to develop ways to predict their biologic behavior. Alterations in adhesion proteins have been shown to participate in proliferation, invasiveness, and metastasis in epithelial tumors. We therefore analyzed the expression of E-cadherin, N-cadherin, as well as their cytosolic binding proteins alpha-catenin, beta-catenin, and gamma-catenin, in 51 paraffin archived and 17 cryopreserved chordoma specimens. In the majority of chordomas, E-cadherin and N-cadherin expression was inversely correlated, whereas beta-catenin and gamma-catenin expression was directly correlated. By multivariate analysis, N-cadherin up-regulation correlated with a diminished recurrence-free survival, and E-cadherin down-regulation strongly correlated with increased probabilities of death as determined by the Kaplan-Meier log-rank test. There was a 3.28-fold increased probability of having a tumor recurrence and a 10.98-fold increased probability of dying when, respectively, N-cadherin was up-regulated and E-cadherin down-regulated. These results suggest that changes in the relative expression of the cadherin-catenin complex reflect chordoma aggressiveness; and that decreased expression of E-cadherin and increased expression of N-cadherin may underlie the transition from a less to a more aggressive tumor phenotype.