Decreased expression of catenins (alpha and beta), p120 CTN, and E-cadherin cell adhesion proteins and E-cadherin gene promoter methylation in prostatic adenocarcinomas

Twist2 is NFkB-responsive when p120-catenin is inactivated and EGFR is overexpressed in esophageal keratinocytes

Esophageal squamous cell carcinoma (ESCC) is among the most aggressive and fatal cancer types. ESCC classically progresses rapidly and frequently causes mortality in four out of five patients within two years of diagnosis. Yet, little is known about the mechanisms that make ESCC so aggressive. In a previous study we demonstrated that p120-catenin (p120ctn) and EGFR, two genes associated with poor prognosis in ESCC, work together to cause invasion. Specifically, inactivation of p120ctn combined with overexpression of EGFR induces a signaling cascade that leads to hyperactivation of NFkB and a resultant aggressive cell type. The purpose of this present study was to identify targets that are responsive to NFkB when p120ctn and EGFR are modified. Using human esophageal keratinocytes, we have identified Twist2 as an NFkB-responsive gene. Interestingly, we found that when NFkB is hyperactivated in cells with EGFR overexpression and p120ctn inactivation, Twist2 is significantly upregulated. Inhibition of NFkB activity results in nearly complete loss of Twist2 expression, suggesting that this potential EMT-inducing gene, is a responsive target of NFkB. There exists a paucity of research on Twist2 in any cancer type; as such, these findings are important in ESCC as well as in other cancer types.

Loss of p120ctn causes EGFR-targeted therapy resistance and failure

Epidermal growth factor receptor (EGFR) plays a vital role in cell division and survival signaling pathways. EGFR is activated in nearly every cancer type, and its high expression in tumors is correlated with poor patient outcome. Altogether, EGFR is a prime candidate as a therapeutic target. While targeted EGFR therapy is initially effective in 75% of patients, a majority of patients relapse within the first year due to poorly understood mechanisms of resistance. p120-catenin (p120ctn) has recently been implicated as a biomarker for EGFR therapy. In previous studies, we demonstrated that p120ctn is a tumor suppressor and its loss is capable of inducing cancer. Furthermore, p120ctn down-regulation synergizes with EGFR overexpression to cause a highly invasive cell phenotype. The purpose of this present study was to investigate whether p120ctn down-regulation induced EGFR therapeutic resistance. Using human esophageal keratinocytes, we have found that EGFR-targeting compounds are toxic to cells overexpressing EGFR. Interestingly, these therapies do not cause toxicity in cells with EGFR overexpression and decreased p120ctn expression. These data suggest that decreased p120ctn causes resistance to EGFR therapy. We believe these findings are of utmost importance, as there is an unmet need to discover mechanisms of EGFR resistance.

Minimal residual disease in prostate cancer patients after primary treatment: theoretical considerations, evidence and possible use in clinical management

Minimal residual disease is that not detected by conventional imaging studies and clinically the patient remains disease free. However, with time these dormant cells will awaken and disease progression occurs, resulting in clinically and radiological detectable metastatic disease. This review addresses the concept of tumor cell dissemination from the primary tumor, the micrometastatic niche and tumor cell survival and finally the clinical utility of detecting and characterizing these tumor cells in order to guide management decisions in treating patients with prostate cancer.

Role of epithelial-mesenchymal transition markers E-cadherin, N-cadherin, β-catenin and ZEB2 in laryngeal squamous cell carcinoma

Epithelial-mesenchymal transition (EMT) allows neoplastic cells to gain the invasive phenotype and become migratory, which is required for cancer progression and metastasis. In the present study, the expression of EMT-associated biomarkers and their association with clinicopathological parameters in laryngeal squamous cell carcinoma (LSCC) was investigated. E-cadherin, N-cadherin, β-catenin and zinc finger E-box binding homeobox 2 (ZEB2) protein expression was evaluated with immunohistochemistry in a cohort of 76 patients with operable LSCC. The association between these transition markers, clinicopathological parameters and their prognostic impact in LSCC was analyzed. Immunohistochemical analysis revealed that EMT-associated proteins were differentially expressed between LSCC and adjacent non-neoplastic laryngeal tissue. Negative E-cadherin expression and positive N-cadherin, β-catenin and ZEB2 expression were associated with a later tumor (T) stage, decreasing tumor differentiation and a reduced overall survival (OS) time (OS: E-cadherin, P=0.016; N-cadherin, P=0.003; β-catenin, P=0.002; ZEB2, P=0.0003). E-cadherin/β-catenin co-expression was significantly associated with the majority of clinicopathological parameters assessed, including lymph node metastases, T stage and tumor cell differentiation (P=0.004, P=0.005, and P<0.001, respectively). Multivariate analysis indicated that T stage and the positive expression of β-catenin and ZEB2 were independent risk factors for OS in LSCC (P=0.014, P=0.025 and P=0.003, respectively). It was concluded that EMT mediates tumor progression, and reduces OS time in patients with LSCC. E-cadherin/β-catenin co-expression may be associated with clinicopathological parameters. T stage, and the positive co-expression of β-catenin and ZEB2 may be independent predictors of prognosis in LSCC.

Epithelial-mesenchymal-transition regulators in prostate cancer: Androgens and beyond

Castration resistant prostate cancer (CRPC) remains one of the leading causes of cancer deaths among men. Conventional therapies targeting androgen signaling driven tumor growth have provided limited survival benefit in patients. Recent identification of the critical molecular and cellular events surrounding tumor progression, invasion, and metastasis to the bone as well as other sites provide new insights in targeting advanced disease. Epithelial mesenchymal transition (EMT) is a process via which epithelial cells undergo morphological changes to a motile mesenchymal phenotype, a phenomenon implicated in cancer metastasis but also therapeutic resistance. Therapeutic targeting of EMT has the potential to open a new avenue in the treatment paradigm of CRPC through the reversion of the invasive mesenchymal phenotype to the well differentiated tumor epithelial tumor phenotype. Overcoming therapeutic resistance in metastatic prostate cancer is an unmet need in today's clinical management of advanced disease. This review outlines our current understanding of the contribution of EMT and its reversal to MET in prostate cancer progression and therapeutic resistance, and the impact of selected targeting of mechanisms of resistance via EMT towards a therapeutic benefit in patients with CRPC.

Morphological and immunohistochemical identification of epithelial-to-mesenchymal transition in clinical prostate cancer

Epithelial-to-mesenchymal transition (EMT) is a process known to be associated with aggressive tumor behavior, metastasis and treatment resistance. It is characterized by coincidental upregulation of mesenchymal markers such as vimentin, fibronectin and N-cadherin concurrent with E-cadherin downregulation. Studies on EMT are generally performed in cell lines and mouse models, while the histopathological and phenotypical properties in clinical prostate cancer (PCa) are still unclear.

The objective of this study was to identify EMT in PCa patients. We demonstrated that N-cadherin, vimentin and fibronectin were generally not co-expressed in corresponding tumor regions. Immunofluorescent double stainings confirmed that co-expression of mesenchymal markers was uncommon, as we found no prostate cancer cells that co-expressed N-cadherin with fibronectin and only rare (<1%) cells that co-expressed N-cadherin with vimentin. Downregulation of E-cadherin was demonstrated in all N-cadherin positive tumor cells, but not in vimentin or fibronectin positive tumor cells. We further analyzed N-cadherin expression in morphologically distinct PCa growth patterns in a radical prostatectomy cohort (n = 77) and found that N-cadherin is preferentially expressed in ill-defined Gleason grade 4 PCa. In conclusion, we demonstrate that N-cadherin is the most reliable marker for EMT in clinical PCa and is preferentially expressed in ill-defined Gleason grade 4 growth pattern.

SOX9 drives WNT pathway activation in prostate cancer

The transcription factor SOX9 is critical for prostate development, and dysregulation of SOX9 is implicated in prostate cancer (PCa). However, the SOX9-dependent genes and pathways involved in both normal and neoplastic prostate epithelium are largely unknown. Here, we performed SOX9 ChIP sequencing analysis and transcriptome profiling of PCa cells and determined that SOX9 positively regulates multiple WNT pathway genes, including those encoding WNT receptors (frizzled [FZD] and lipoprotein receptor-related protein [LRP] family members) and the downstream β-catenin effector TCF4. Analyses of PCa xenografts and clinical samples both revealed an association between the expression of SOX9 and WNT pathway components in PCa. Finally, treatment of SOX9-expressing PCa cells with a WNT synthesis inhibitor (LGK974) reduced WNT pathway signaling in vitro and tumor growth in murine xenograft models. Together, our data indicate that SOX9 expression drives PCa by reactivating the WNT/β-catenin signaling that mediates ductal morphogenesis in fetal prostate and define a subgroup of patients who would benefit from WNT-targeted therapy.

Promoter methylation and polymorphism of E-cadherin gene may confer a risk to prostate cancer: a meta-analysis based on 22 studies

Emerging evidence has suggested that -160C/A polymorphism and promoter methylation of E-cadherin gene may contribute to the risk of prostate cancer. However, the results are still conflicting. We aim to systematically evaluate the potential of promoter methylation and polymorphism in E-cadherin gene to confer a risk to prostate cancer through meta-analysis. PubMed, Embase, Web of Science, Cochrane Library, and Chinese National Knowledge Infrastructure (CNKI) databases were searched to identify eligible studies published before April 1, 2014. Pooled odds ratios (ORs) with their 95 % confidence intervals (95 % CIs) were calculated by using the random-effect model or the fixed-effect model, according to heterogeneity test. Subgroup analyses were also performed to explore the potential sources of heterogeneity. Sensitivity and publication bias analyses were used to test the robustness of our results. We performed a meta-analysis of 22 included studies, with 11 on -160C/A polymorphism and another 11 on promoter methylation of E-cadherin gene. Our meta-analysis results suggested that E-cadherin -160C/A polymorphism may be a potential risk factor for prostate cancer. Furthermore, we observed that the frequencies of promoter methylation of E-cadherin gene in the prostate cancer tissues were significantly higher than those of normal tissues, indicating that promoter methylation of E-cadherin gene may play an important role in prostate carcinogenesis. In conclusion, the present meta-analysis provides further evidence that promoter methylation and -160C/A polymorphism of E-cadherin gene may confer a risk to prostate cancer. Identifying these risk factors for prostate cancer will improve early detection, allow for selective chemoprevention, and provide further insights into its disease mechanisms.

Expression of β-catenin and mesenchymal markers in canine prostatic hyperplasia and carcinoma

β-catenin is a nuclear signalling molecule that is associated with human prostatic neoplasia and the epithelial-mesenchymal transition (EMT) process. The present study evaluates immunohistochemically the expression of β-catenin and the mesenchymal markers vimentin, desmin, calponin and smooth muscle actin (SMA) in four normal canine prostates and prostate samples from 15 dogs with benign prostatic hyperplasia (BPH) and six with prostatic carcinoma (PC). β-catenin was located on the membrane of normal epithelial cells, while the same marker had both cytoplasmic and membrane expression in hyperplastic cells and a nuclear redistribution in PC. Vimentin-positive luminal cells were observed in two of the 15 cases of BPH and in all PC samples, suggesting the conversion of neoplastic epithelial cells to a mesenchymal type. SMA was consistently negative in PC, but there was mild desmin and calponin immunoreactivity in these lesions. As in men, β-catenin is involved in canine prostatic carcinogenesis, thus further validating the use of this animal model to study human prostatic disease.

p120 catenin: an essential regulator of cadherin stability, adhesion-induced signaling, and cancer progression

p120 catenin is the best studied member of a subfamily of proteins that associate with the cadherin juxtamembrane domain to suppress cadherin endocytosis. p120 also recruits the minus ends of microtubules to the cadherin complex, leading to junction maturation. In addition, p120 regulates the activity of Rho family GTPases through multiple interactions with Rho GEFs, GAPs, Rho GTPases, and their effectors. Nuclear signaling is affected by the interaction of p120 with Kaiso, a transcription factor regulating Wnt-responsive genes as well as transcriptionally repressing methylated promoters. Multiple alternatively spliced p120 isoforms and complex phosphorylation events affect these p120 functions. In cancer, reduced p120 expression correlates with reduced E-cadherin function and with tumor progression. In contrast, in tumor cells that have lost E-cadherin expression, p120 promotes cell invasion and anchorage-independent growth. Furthermore, p120 is required for Src-induced oncogenic transformation and provides a potential target for future therapeutic interventions.

LRP5 knockdown: effect on prostate cancer invasion growth and skeletal metastasis in vitro and in vivo

Prostate cancer (PCa) is a common hormone-dependent malignancy associated with the development of skeletal metastases. This is due to the increased expression of a number of growth factors, cytokines, and proteases which collectively drive the metastatic cascade in general and increased propensity to develop skeletal metastasis in particular. While a number of signaling pathways have been implicated in PCa progression, the highly complex wnt/β-catenin pathway is unique due to its ability to regulate gene expression, cell invasion, migration, survival, proliferation, and differentiation to contribute in the initiation and progression of PCa. Members of the wnt family bind to the Frizzle proteins or lipoprotein-related receptor proteins 5, 6 (LRP5, -6) to activate this key pathway. In the current study, we have investigated the role of wnt/β-catenin pathway in PCa progression, skeletal metastasis, and gene expression using the dominant negative plasmid of LRP5 (DN-LRP5) and human PCa cells PC-3. Inactivation of LRP5 resulted in mesenchymal to epithelial shift, lack of translocation of β-catenin to cell surface, increased tumor cell proliferation, decreased colony formation, migration and invasion in vitro. These effects were attributed to decreased expression of pro-invasive and pro-metastatic genes. In in vivo studies, PC-3-DN-LRP5 cells developed significantly smaller tumors and a marked decrease in skeletal lesion area and number as determined by X-ray, micro (μ) CT and histological analysis. Collectively results from these studies demonstrate the dominant role of this key pathway in PCa growth and skeletal metastasis and its potential as a viable therapeutic target.

Nuclear Kaiso indicates aggressive prostate cancers and promotes migration and invasiveness of prostate cancer cells

Kaiso, a p120 catenin-binding protein, is expressed in the cytoplasmic and nuclear compartments of cells; however, the biological consequences and clinical implications of a shift between these compartments have yet to be established. Herein, we report an enrichment of nuclear Kaiso expression in cells of primary and metastatic prostate tumors relative to the normal prostate epithelium. Nuclear expression of Kaiso correlates with Gleason score (P < 0.001) and tumor grade (P < 0.001). There is higher nuclear expression of Kaiso in primary tumor/normal matched samples and in primary tumors from African American men (P < 0.0001). We further found that epidermal growth factor (EGF) receptor up-regulates Kaiso at the RNA and protein levels in prostate cancer cell lines, but more interestingly causes a shift of cytoplasmic Kaiso to the nucleus that is reversed by the EGF receptor-specific kinase inhibitor, PD153035. In both DU-145 and PC-3 prostate cancer cell lines, Kaiso inhibition (short hairpin RNA-Kaiso) decreased cell migration and invasion even in the presence of EGF. Further, Kaiso directly binds to the E-cadherin promoter, and inhibition of Kaiso in PC-3 cells results in increased E-cadherin expression, as well as re-establishment of cell-cell contacts. In addition, Kaiso-depleted cells show more epithelial morphology and a reversal of the mesenchymal markers N-cadherin and fibronectin. Our findings establish a defined oncogenic role of Kaiso in promoting the progression of prostate cancer.

Aberrant DNA methylation and prostate cancer

Prostate cancer (PCa) is the most prevalent cancer, a significant contributor to morbidity and a leading cause of cancer-related death in men in Western industrialized countries. In contrast to genetic changes that vary among individual cases, somatic epigenetic alterations are early and highly consistent events. Epigenetics encompasses several different phenomena, such as DNA methylation, histone modifications, RNA interference, and genomic imprinting. Epigenetic processes regulate gene expression and can change malignancy-associated phenotypes such as growth, migration, invasion, or angiogenesis. Methylations of certain genes are associated with PCa progression. Compared to normal prostate tissues, several hypermethylated genes have also been identified in benign prostate hyperplasia, which suggests a role for aberrant methylation in this growth dysfunction. Global and gene-specific DNA methylation could be affected by environmental and dietary factors. Among other epigenetic changes, aberrant DNA methylation might have a great potential as diagnostic or prognostic marker for PCa and could be tested in tumor tissues and various body fluids (e.g., serum, urine). The DNA methylation markers are simple in nature, have high sensitivity, and could be detected either quantitatively or qualitatively. Availability of genome-wide screening methodologies also allows the identification of epigenetic signatures in high throughput population studies. Unlike irreversible genetic changes, epigenetic alterations are reversible and could be used for PCa targeted therapies.

Integrin-linked kinase (ILK) expression correlates with tumor severity in clear cell renal carcinoma

Integrin-linked kinase (ILK) is an unique intracellular serine/threonine kinase and adapter protein. When dysregulated, it has been associated with increased cell proliferation, anchorage-independent cell growth, evasion of apoptosis, angiogenesis, invasion of surrounding tissues, downregulation of E-cadherin expression, nuclear translocation of β-catenin and metastasis, all features of tumoral malignancy. The objective of the present work was to evaluate the expression of ILK in clear cell renal carcinomas (CCRC) as a possible prognostic indicator. ILK immunoexpression was evaluated in a tissue microarray (TMA) with 45 human CCRCs. In addition, the apoptotic and proliferative indices and the immuno-expression of β-catenin and E-cadherin were also evaluated. E-cadherin expression was significantly decreased in tumors with positive ILK expression in relation to those with negative immunoexpression (p = 0.011). ILK immunostaining was significantly increased in high-grade in comparison to low-grade CCRCs (p = 0.0008). ILK expression was also associated with increased proliferative index (p = 0.020), tumor size >7.0 cm (p = 0.018) and with renal vein and capsule invasion (p = 0.003 and p = 0.00). Finally, tumors stage I and II (noninvasive) presented significantly reduced ILK immunoexpression when compared to stage III (locally invasive) (p = 0.0028). ILK immunoexpression in CCRC increases with loss of intercellular adhesion, nuclear grading, increased proliferative index and Robson stage. Altogether, our data suggest a possible role for ILK in the progression of CRCC.

Wnt/β-catenin signalling in prostate cancer

The Wnts are secreted cysteine-rich glycoproteins that have important roles in the developing embryo as well as in tissue homeostasis in adults. Dysregulation of Wnt signalling can lead to several types of cancer, including prostate cancer. A hallmark of the signalling pathway is the stabilization of the transcriptional co-activator β-catenin, which not only regulates expression of many genes implicated in cancer but is also an essential component of cadherin cell adhesion complexes. β-catenin regulates gene expression by binding members of the T-cell-specific transcription factor/lymphoid enhancer-binding factor 1 (TCF/LEF-1) family of transcription factors. In addition, β-catenin associates with the androgen receptor, a key regulator of prostate growth that drives prostate cancer progression. Wnt/β-catenin signalling can be controlled by secreted Wnt antagonists, many of which are downregulated in cancer. Activation of the Wnt/β-catenin pathway has effects on prostate cell proliferation, differentiation and the epithelial-mesenchymal transition, which is thought to regulate the invasive behaviour of tumour cells. However, whether targeting Wnt/β-catenin signalling is a good therapeutic option for prostate cancer remains unclear.

The cadherin-catenin complex in laryngeal squamous cell carcinoma

Abnormal Wnt signaling and impaired cell–cell adhesion due to abnormal E-cadherin and β-catenin function have been implicated in many cancers, but have not been fully explored in laryngeal squamous cell carcinoma. In this study, β-catenin cellular location and E-cadherin expression levels were analyzed in 16 laryngeal squamous cell carcinomas (LSCCs) (9 glottic and 7 supraglottic) and 11 samples of non-tumoral inflammatory larynx tissue, using immunohistochemical methods. All non-tumoral tissues showed equally strong membranous expression of β-catenin, while cytoplasmic expression was found in only 3 of the 11 samples. By contrast, whereas 8/9 glottic LSCCs exhibited only membranous expression of β-catenin, 6/7 supraglottic LSCCs displayed both membranous and cytoplasmic expression (p = 0.003). Strong E-cadherin staining was observed in 9/11 non-tumoral tissues and 7/9 glottic LSCCs, whereas 4/7 supraglottic LSCCs exhibited weak expression. Reduced membrane expression of E-cadherin and cytoplasmic retention of β-catenin in supraglottic LSCC seems to be related with more aggressive biological behavior which has been described in clinical studies. Further research is required to clarify the involvement of β-catenin in the mechanism associated with malignant transformation in laryngeal tissues.

Epigenetic regulation of prostate cancer

Prostate cancer is a commonly diagnosed cancer in men and a leading cause of cancer deaths. Whilst the underlying mechanisms leading to prostate cancer are still to be determined, it is evident that both genetic and epigenetic changes contribute to the development and progression of this disease. Epigenetic changes involving DNA hypo- and hypermethylation, altered histone modifications and more recently changes in microRNA expression have been detected at a range of genes associated with prostate cancer. Furthermore, there is evidence that particular epigenetic changes are associated with different stages of the disease. Whilst early detection can lead to effective treatment, and androgen deprivation therapy has a high response rate, many tumours develop towards hormone-refractory prostate cancer, for which there is no successful treatment. Reliable markers for early detection and more effective treatment strategies are, therefore, needed. Consequently, there is a considerable interest in the potential of epigenetic changes as markers or targets for therapy in prostate cancer. Epigenetic modifiers that demethylate DNA and inhibit histone deacetylases have recently been explored to reactivate silenced gene expression in cancer. However, further understanding of the mechanisms and the effects of chromatin modulation in prostate cancer are required. In this review, we examine the current literature on epigenetic changes associated with prostate cancer and discuss the potential use of epigenetic modifiers for treatment of this disease.

Aberrant β-catenin expression in the histologic differentiation of oral squamous cell carcinoma and verrucous carcinoma: an immunohistochemical study

β-Catenin acts as a structural protein at cell-cell adherens junctions and as a transcription activator mediating Wnt signal transduction. Altered β-catenin expression has been associated with loss of cell differentiation and acquisition of an invasive phenotype. In the present study, β-catenin expression was compared immunohistochemically between oral squamous cell carcinoma (30 cases) and verrucous carcinoma (30 cases), and correlated with different histological grades of oral squamous cell carcinoma. Positivity for β-catenin was seen in 17 cases (56.6%) of oral squamous cell carcinoma and 25 cases (83.3%) of verrucous carcinoma, and was significantly correlated with the grade of oral squamous cell carcinoma, whereas no significant correlation of β-catenin expression was observed between oral squamous cell carcinoma and verrucous carcinoma. In oral squamous cell carcinoma, the number of β-catenin-positive cases and the intensity of expression decreased as cancers became more poorly differentiated. Decreased membranous localization and intense cytoplasmic staining were observed in poorly differentiated squamous cell carcinoma. In verrucous carcinoma, β-catenin was demonstrable mainly in the membrane. Down-regulation of β-catenin was significantly correlated with lack of differentiation in oral squamous cell carcinoma. Reduced membranous expression and predominant cytoplasmic localization were prominent among higher-grade tumors, suggesting stabilization of β-catenin and its role as a signaling molecule. Predominant membranous expression in verrucous carcinoma was similar to that observed in well differentiated squamous cell carcinoma, thus corroborating its role in cell adhesion in these subgroups.

The cadherin-catenin complex in nasopharyngeal carcinoma

Abnormal Wnt signaling and impaired cell–cell adhesion due to abnormal E-cadherin and β-catenin function have been implicated in many cancers, but have not been fully explored in nasopharyngeal carcinoma. The aim of this study was to analyze β-Catenin cellular location and E-cadherin expression levels in nasopharyngeal carcinoma. E-cadherin expression levels were also correlated with clinical data and underlying pathology. β-Catenin and E-cadherin expression were examined in 18 nasopharyngeal carcinoma and 7 non-tumoral inflammatory pharynx tissues using immunohistochemical methods. Patient clinical data were collected, and histological evaluation was performed by hematoxylin/eosin staining. β-catenin was detected in membrane and cytoplasm in all cases of nasopharyngeal carcinoma, regardless of histological type; in non-tumoral tissues, however, β-catenin was observed only in the membrane. As for E-cadherin expression levels, strong staining was observed in most non-tumoral tissues, but staining was only moderate in nasopharyngeal carcinoma tissues. E-cadherin expression was associated with β-catenin localization, study group, metastatic disease, and patient outcomes. Reduced levels of E-cadherin protein observed in nasopharyngeal carinoma may play an important role in invasion and metastasis. Cytoplasmic β-catenin in nasopharyngeal carcinoma may impair cell–cell adhesion, promoting invasive behavior and a metastatic tumor phenotype.

Altered expression of cell adhesion molecules leads to differential uptake of hypericin in urothelial cancer

OBJECTIVE

To elucidate the mechanism behind selective uptake of hypericin in bladder cancer after intravesical instillation for photodynamic diagnosis of urothelial cell carcinoma of bladder.

PATIENTS AND METHODS

Clinical studies were done on a series of 60 bladder cancer biopsies obtained from 28 patients who received intravesical instillations with 8 μM hypericin. Serial 5 μm cryosections were cut from 43 biopsies, and expression of the E-cadherin and associated catenins were determined using immunohistochemical and immunofluorescence staining. Hypericin was assessed using fluorescence confocal laser scanning microscopy. In addition, mRNA expression of these cell-adhesion molecules was analyzed in 17 biopsies using reverse transcription-PCR.

RESULTS

Increased variability in the expression of E-cadherin and associated molecules was found in high-grade, advanced stage bladder carcinoma. An inverse association was found between immunoreactivity for E-cadherin, β- and γ-catenin, and both stage and grade of cancer (P < 0.05). A positive association was observed between the hypericin fluorescence and tumor grade. There was a significant down-regulation of E-cadherin and β-catenin mRNA in grade 2 and 3 tumors. Although a small sample size was studied, it provided sufficient proof to support the hypothesis that altered expression of cell adhesion molecules would lead to preferential hypericin uptake in urothelial cell carcinoma.

CONCLUSIONS

Our study has unraveled one of the many factors contributing to the selective uptake of hypericin in bladder cancer. We have thus identified the effects of alteration of E-cadherin-catenin complex and transformed intercellular junction in the modified paracellular uptake of hypericin that provides the rationale for using this photosensitizer in photodynamic diagnosis of bladder carcinoma.

p120ctn and P-cadherin but not E-cadherin regulate cell motility and invasion of DU145 prostate cancer cells

Background

Adherens junctions consist of transmembrane cadherins, which interact intracellularly with p120ctn, ß-catenin and α-catenin. p120ctn is known to regulate cell-cell adhesion by increasing cadherin stability, but the effects of other adherens junction components on cell-cell adhesion have not been compared with that of p120ctn.

Methodology/Principal Findings

We show that depletion of p120ctn by small interfering RNA (siRNA) in DU145 prostate cancer and MCF10A breast epithelial cells reduces the expression levels of the adherens junction proteins, E-cadherin, P-cadherin, ß-catenin and α-catenin, and induces loss of cell-cell adhesion. p120ctn-depleted cells also have increased migration speed and invasion, which correlates with increased Rap1 but not Rac1 or RhoA activity. Downregulation of P-cadherin, β-catenin and α-catenin but not E-cadherin induces a loss of cell-cell adhesion, increased migration and enhanced invasion similar to p120ctn depletion. However, only p120ctn depletion leads to a decrease in the levels of other adherens junction proteins.

Conclusions/Significance

Our data indicate that P-cadherin but not E-cadherin is important for maintaining adherens junctions in DU145 and MCF10A cells, and that depletion of any of the cadherin-associated proteins, p120ctn, ß-catenin or α-catenin, is sufficient to disrupt adherens junctions in DU145 cells and increase migration and cancer cell invasion.

Breast carcinoma cells re-express E-cadherin during mesenchymal to epithelial reverting transition

BACKGROUND

Epithelial to mesenchymal transition (EMT), implicated as a mechanism for tumor dissemination, is marked by loss of E-cadherin, disruption of cell adhesion, and induction of cell motility and invasion. In most intraductal breast carcinomas E-cadherin is regulated epigenetically via methylation of the promoter. E-cadherin expression is therefore dynamic and open to modulation by the microenvironment. In addition, it has been observed that metastatic foci commonly appear more differentiated than the primary tumor, suggesting that cancer cells may further undergo a mesenchymal to epithelial reverting transition (MErT) in the secondary organ environment following the EMT that allows for escape.

RESULTS

We first examined E-cadherin expression in primary breast tumors and their corresponding metastases to liver, lung and brain and discovered that 62% (10/16) of cases showed increased E-cadherin expression in the metastases compared to the primaries. These observations led to the question of whether the positive metastatic foci arose from expansion of E-cadherin-positive cells or from MErT of originally E-cadherin-negative disseminated cells. Thus, we aimed to determine whether it was possible for the mesenchymal-like MDA-MB-231 breast cancer cells to undergo an MErT through the re-expression of E-cadherin, either through exogenous introduction or induction by the microenvironment. Ectopic expression of full-length E-cadherin in MDA-MB-231 cells resulted in a morphological and functional reversion of the epithelial phenotype, with even just the cytosolic domain of E-cadherin yielding a partial phenotype. Introduction of MDA-MB-231 cells or primary explants into a secondary organ environment simulated by a hepatocyte coculture system induced E-cadherin re-expression through passive loss of methylation of the promoter. Furthermore, detection of E-cadherin-positive metastatic foci following the spontaneous metastasis of MDA-MB-231 cells injected into the mammary fat pad of mice suggests that this re-expression is functional.

CONCLUSIONS

Our clinical observations and experimental data indicate that the secondary organ microenvironment can induce the re-expression of E-cadherin and consequently MErT. This phenotypic change is reflected in altered cell behavior and thus may be a critical step in cell survival at metastatic sites.

E-cadherin and beta-catenin loss of expression related to bone metastasis in prostate cancer

OBJECTIVES

E-cadherin and beta-catenin are adhesion molecules responsible for the maintenance of normal epithelial cell phenotype. A disturbance in epithelial cell adhesion, which leads to a more invasive and metastatic phenotype, is a hallmark of tumor progression. Several immunohistochemical studies have reported a strong correlation between loss of their expression to higher stage and grade in prostate carcinoma, but their influence in metastatic process is not yet known. The aim of this study is to verify the role of adhesion molecules in the progression of prostate cancer (PC), assessing the expression of E-cadherin and beta-catenin in bone metastasis.

MATERIALS AND METHODS

Twenty-eight bone metastases of prostate carcinoma were submitted to immunohistochemistry analysis for E-cadherin and beta-catenin expression. In 6 patients, we were able to assess the expression of the adhesion molecules in the primary tumors and their respective metastases. The definition of normal expression for both antibodies was strong and diffuse expression in more than 70% of tumor cells.

RESULTS

In bone metastases, there was loss of expression of E-cadherin and beta-catenin in 86% and 82%, respectively. Among the primary tumors, E-cadherin and beta-catenin expression was normal in 83% and 50% cases, respectively. Considering the 6 patients with paired primary and bone metastasis, we found loss of expression for both E-cadherin and beta-catenin in most of the cases.

CONCLUSIONS

Comparing primary PC and its metastasis, we showed persistent loss of E-cadherin and beta-catenin expression. This phenomenon may be related to metastatic potential in PC, because we have shown underexpression for E-cadherin and beta-catenin in 86% and 82% of bone metastases.

APC promoter hypermethylation is an early event in endometrial tumorigenesis

The aim of the current study was to investigate the role of promoter methylation of adenomatous polyposis coli (APC) and epithelial cadherin (E-cadherin) genes in endometrial tumorigenesis. The methylation status of both genes was investigated in 43 cases of normal endometrium, 21 simple hyperplasia, 17 atypical hyperplasia, and 86 endometrial carcinoma (EC). Additionally, the methylation pattern of both genes was analyzed in 24 primary ECs and their corresponding metastases. DNA methylation of the APC gene increased from atypical hyperplasia (23.5%) to endometrial carcinoma, reaching its highest level of 77.4% in early stage cancer (FIGO I and II) and decreasing stepwise to 24.2% in advanced stage carcinomas (FIGO III and IV). No methylation of APC was found in normal endometrium or simple hyperplasia. Methylation of E-cadherin was found only in EC (22.1%). The mean age of the patients with aberrant APC methylation was 68.8 years and was significantly higher compared to the mean age (60.9 years) of the patients without methylation of APC promoter (P = 0.02). APC promoter methylation significantly correlated with decreased protein expression of APC (P = 0.039), with increased expression of the Ki-67 proliferative marker (P = 0.006) and decreased metastatic potential (P = 0.002). There was no correlation between APC and E-cadherin methylation patterns and the other clinicopathologic features, nor with patient outcome. Our results suggest that hypermethylation of APC promoter region is an early event in endometrial tumorigenesis.

β-Catenin expression in benign and malignant salivary gland tumors

OBJECTIVE

To assess the expression of β-catenin in benign and malignant salivary gland tumors and to investigate the possible role of β-catenin in the behavior of salivary gland tumors.

STUDY DESIGN

Paraffin embedded tissues from 45 salivary gland tumors were studied immunohistochemically for expression of β-catenin.

RESULT

Reduced/aberrant β-catenin expression was seen in benign and malignant salivary gland tumors. Cytoplasmic localization and reduced membranous expression were comparatively observed more in malignant salivary gland tumors. Additionally, in pleomorphic adenomas (PAs), β-catenin exhibited intense staining in cells arranged in the form of ducts/tubules, whereas cells in clusters and sheets showed weaker immunoreactivity.

CONCLUSION

Reduced and cytoplasmic localization of β-catenin could indicate lack of differentiation, invasive potential, and aggressive behavior in malignant salivary gland tumors. Furthermore, change in expression based on the arrangement of tumor cells may suggest that β-catenin may have a role in morphological variations seen in PAs.

Estrogen regulates DNA methyltransferase 3B expression in Ishikawa endometrial adenocarcinoma cells

It is well-known that exposure to unopposed estrogen is considered as an important risk factor for endometrial cancer. Recent studies have shown that over-expression of DNA methyltransferases (DNMTs) are involved in the development of endometrial cancer. Therefore, the present study was undertaken to elucidate the impact of estrogen on the expression of DNMTs in endometrial cancer. Ishikawa cell line was used. Flow cytometry analysis demonstrated that 17 beta-estradiol (E(2)) enhanced the cell proliferation with a peak at 10(-8) M. Over-expression of DNMT3B treated with E(2) was confirmed by real-time PCR and western blotting analysis. Furthermore, the up-regulation of DNMT3B expression induced by E(2) was suppressed by the addition of ICI182780. However, we did not observe changes in the expression of DNMT1. Our study suggests that estrogen up-regulating the expression of DNMT3B in an ER-dependent pathway may be a possible mechanism for estrogen facilitates the malignant transformation of endometrial cancer cells.

BCCIP associates with the receptor protein tyrosine phosphatase PTPmu

The receptor protein tyrosine phosphatase PTPmu belongs to a family of adhesion molecules that contain cell-cell adhesion motifs in their extracellular segments and catalytic domains within their intracellular segments. The ability of PTPmu both to mediate adhesion and exhibit enzymatic activity makes PTPmu an excellent candidate to transduce signals in response to cell-cell adhesion. In an effort to identify downstream signaling partners of PTPmu, we performed a modified yeast two-hybrid screen using the first tyrosine phosphatase domain of PTPmu as bait. We isolated an interacting clone encoding BRCA2 and CDKN1A interacting protein (BCCIP) from a HeLa cell library. BCCIP is a p21 and BRCA2 interacting protein that has been shown to play roles in both cell cycle arrest and DNA repair. In this manuscript, we confirm the interaction between BCCIP and PTPmu identified in yeast using in vitro biochemical studies and characterize BCCIP as a PTPmu binding protein. We demonstrate that BCCIP is phosphorylated by the Src tyrosine kinase and dephosphorylated by the PTPmu tyrosine phosphatase in vitro. Furthermore, we show that BCCIP is required for both the permissive and repulsive functions of PTPmu in neurite outgrowth assays, suggesting BCCIP and PTPmu are in a common signal transduction pathway.

Analysis of APC, alpha-, beta-catenins, and N-cadherin protein expression in aggressive fibromatosis (desmoid tumor)

The aims of this study were to analyze the cadherin/catenin adhesion complex in cells from abdominal and extra-abdominal aggressive fibromatosis tumors, and to estimate the correlation between the expression of the tested proteins and the clinical data of the desmoid patients. Immunohistochemistry was used to examine the expression of the cadherin/catenin adhesion complex: APC protein, alpha-, beta-catenin, and N-cadherin in archival material derived from 15 cases of extra-abdominal desmoid tumor (E-AD) and 20 cases of abdominal (AD) desmoid tumor. The tested proteins demonstrated cytoplasmic (c) staining. Furthermore, nuclear (n) or cytoplasmic and nuclear (c+n) staining was observed for beta-catenin. The mean values of the percentage of positive cells for the tested proteins between E-AD vs. AD did not demonstrate any statistically significant difference except for alpha-catenin. In the E-AD group, in both cases of recurrent tumors, no alpha-catenin expression was observed but the expression of this protein was detected in primary tumors. In the groups investigated, no statistically significant correlation was found between alpha-catenin, beta-catenin (c), (n) and (c+n) expression, and tumor size (p>0.1). The results regarding beta-catenin expression obtained in our study confirm the previous findings that nuclear accumulation of this protein plays a crucial role in the pathogenesis of aggressive fibromatosis.

Suppression of Wnt/beta-catenin signaling inhibits prostate cancer cell proliferation

Although mounting evidence has demonstrated an important role of Wnt/beta-catenin signaling in the development and progression of cancer, the therapeutic potential of small molecules that target this pathway for prostate cancer remains largely unknown. We reported herein that the highly invasive androgen-independent PC-3 and DU145 human prostate cancer cells exhibited higher levels of Wnt/beta-catenin signaling than the androgen-dependent LNCaP prostate cancer cells and non-cancerous PZ-HPV-7 and PWR-1E prostate cells, and that exogenous Wnt3A treatment exaggerated the difference of the Wnt/beta-catenin signaling levels among these prostate cells. Furthermore, we demonstrated that the non-steroidal anti-inflammatory drug, sulindac sulfide, the cyclooxygenase-2 (COX-2) selective inhibitor, celecoxib, and the nitric oxide-donating aspirin derivative, NO-ASA, blocked Wnt/beta-catenin signaling in PC-3 and DU145 cells. These effects occurred at concentrations comparable to those required to inhibit cell proliferation, indicating that the inhibitory effect of these drugs on prostate cancer cell proliferation may involve the suppression of Wnt/beta-catenin signaling. Finally, we showed that a novel small molecule inhibitor of Wnt/beta-catenin signaling, PKF118- 310, inhibited Wnt/beta-catenin signaling and proliferation in prostate cancer cells within the same concentration range. Together, these results suggest that small molecules that inhibit Wnt/beta-catenin signaling have therapeutic potential for the prevention or treatment of prostate cancer.

Unmethylated E-cadherin gene expression is significantly associated with metastatic human prostate cancer cells in bone

BACKGROUND

The concurrent determination of methylation status of E-cadherin gene and E-cadherin protein expression remains scant in metastatic prostate cancer cells in bone, the most prevalent site for metastatic growth. Therefore, the study was undertaken to ascertain the methylation status of E-cadherin gene, a most frequent and known epigenetic mechanism of its regulation, and the protein expression in prostate tissue biopsy specimen.

METHODS

The methylation of E-cadherin gene was determined by methylation specific-PCR and the protein expression by immunohistochemical method in the consecutive sections of each prostate tissue biopsy specimen.

RESULTS

The unmethylated E-cadherin gene and homogeneous E-cadherin protein expression was significantly associated with BPH as compared to the primary prostate carcinoma (Fisher's Exact P < 0.001). A significant association was observed between the concurrent methylated gene and markedly reduced expression of the protein in the primary prostate cancer cells as compared to the BPH cells, suggesting methylation-dependent regulation of the gene expression in these cases. In contrast to the primary cancer, a highly significant increase in the frequency of metastatic prostate cancer cells in bone exhibited the concurrent expression of unmethylated gene and homogeneous protein (Fisher's Exact P < 0.001).

CONCLUSIONS

The study clearly demonstrated a significant association of the concurrent expression of unmethylated E-cadherin gene and E-cadherin protein with metastatic prostate cancer cells in bone, and that its expression may have a role in the intercellular adhesion in the formation of metastatic lesions in bone.

Derailed endocytosis: an emerging feature of cancer

Once engaged by soluble or matrix-anchored ligands, cell surface proteins are commonly sorted to lysosomal degradation through several endocytic pathways. Defective vesicular trafficking of growth factor receptors, as well as unbalanced recycling of integrin- and cadherin-based adhesion complexes, has emerged in the past 5 years as a multifaceted hallmark of malignant cells. In line with the cooperative nature of endocytic machineries, multiple oncogenic alterations underlie defective endocytosis, such as altered ubiquitylation (Cbl and Nedd4 ubiquitin ligases, for example), altered cytoskeletal interactions and alterations to Rab family members. Pharmaceutical interception of the propensity of tumour cells to derail their signalling and their adhesion receptors may constitute a novel target for cancer therapy.

Benign, malignant salivary gland tumors: comparison of immunohistochemical expression of e-cadherin

The aim of the present study was to assess any variation in the immunohistochemical expression of E-cadherin in benign and malignant salivary gland tumors. A total of 60 cases of benign and malignant salivary gland tumors were evaluated immunohistochemically for E-cadherin expression. These included 10 cases of pleomorphic adenoma (PA), 2 cases of canalicular adenoma (CA), 2 cases of myoepithelioma (MY), 24 cases of adenoid cystic carcinoma (ACC), 12 cases of mucoepidermoid carcinoma (MEC), 9 cases of adenocarcinoma (AC) and 1 case of carcinoma ex pleomorphic adenoma (Ca Ex PA). 48 cases (80%) showed positive expression, in which benign tumors exhibited relatively increased reactivity (85.7%) as compared to the malignant tumors (78.3%). 10 PA, 2 MY, 20 ACC, 9 MEC, 6 AC and 1 Ca Ex PA expressed E-cadherin. Negative expression was evident in CA, ACC, MEC and AC. Statistically significant reduction in reactivity was evident in mucoepidermoid carcinoma and adenocarcinoma, when compared to pleomorphic adenoma.

Gene panel model predictive of outcome in men at high-risk of systemic progression and death from prostate cancer after radical retropubic prostatectomy

PURPOSE

In men who are at high-risk of prostate cancer, progression and death from cancer after radical retropubic prostatectomy (RRP), limited prognostic information is provided by established prognostic features. The objective of this study was to develop a model predictive of outcome in this group of patients.

METHODS

Candidate genes were identified from microarray expression data from 102 laser capture microdissected prostate tissue samples. Candidates were overexpressed in tumor compared with normal prostate and more frequently in Gleason patterns 4 and 5 than in 3. A case control study of 157 high-risk patients, matched on Gleason score and stage with systemic progression or death of prostate cancer as the end point, was used to evaluate the expression of candidate genes and build a multivariate model. Tumor was collected from the highest Gleason score in paraffin-embedded blocks and the gene expression was quantified by real-time reverse transcription polymerase chain reaction. Validation of the final model was performed on a separate case-control study of 57 high-risk patients who underwent RRP.

RESULTS

A model incorporating gene expression of topoisomerase-2a, cadherin-10, the fusion status based on ERG, ETV1, and ETV4 expression, and the aneuploidy status resulted in a 0.81 area under the curve (AUC) in receiver operating characteristic statistical analysis for the identification of men with systemic progression and death from high grade prostate cancer. The AUC was 0.79 in the independent validation study.

CONCLUSION

The model can identify men with high-risk prostate cancer who may benefit from more intensive postoperative follow-up and adjuvant therapies.

Alterations in beta-catenin expression and localization in prostate cancer

BACKGROUND

Wnt signaling is thought to be important in prostate cancer, in part because proteins such as beta-catenin can also affect androgen receptor signaling. beta-Catenin forms a cell adhesion complex with E-cadherin raising the possibility that loss of expression or a change in beta-catenin distribution in the cell could also alter downstream signaling, decreased inter-cellular adhesion and the promotion of metastasis. A number of studies have reported the altered expression and/or localization of beta-catenin as a biomarker in prostate cancer.

METHODS

Tissue microarrays comprised of BPH and low, moderate and high-grade prostate cancer (n=77) were assessed for beta-catenin expression and distribution using immunohistochemistry. Staining was also performed on a tissue microarray containing tissue from patients before and after hormone manipulation. The effects of fixation and different antibodies was assessed on fixed LNCaP cell pellets and small prostate tissue microarrays.

RESULTS

We have observed increased beta-catenin expression in only high Gleason score (>7) prostate cancer. A nuclear re-distribution of beta-catenin has previously been reported. We noted nuclear beta-catenin in benign prostatic hyperplasia and a gradual loss in nuclear distribution with increasing Gleason grade. We found no evidence for an alteration in beta-catenin expression or re-distribution with hormone ablation. Altered fixation, antibodies and antibody concentration did affect the intensity and specificity of staining.

CONCLUSIONS

A loss of nuclear beta-catenin is the most consistent feature in prostate cancer rather than absolute levels of expression. We also suggest that variation in immunohistochemical protocols may explain variations in the reported literature.

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.

Overexpression of E-cadherin and beta-catenin proteins in metastatic prostate cancer cells in bone

BACKGROUND

The expression of E-cadherin in the intercellular adhesion of metastatic prostate cancer cells in bone, which is the most prevalent site of metastatic growth, remains elusive.

METHODS

The aim of the study was to compare the concurrent membranous expression of E-cadherin and beta-catenin proteins, the state which is known to be associated with the cellular adhesion function of E-cadherin, in prostate biopsy tissue specimens by immunohistochemical staining method. The expression patterns of E-cadherin or beta-catenin were classified as homogeneous (most cells exhibiting positively), heterogeneous (a few scattered patches of cells with positivity) or negative.

RESULTS

Benign prostate hyperplasia cells exhibited homogeneous expression of both E-cadherin and beta-catenin in 9 of 11 (82%), whereas the primary prostate cancer cells were homogeneously positive for both proteins only in 4 of 22 (18%) of the cases. The results are similar to those reported in literature. However, in contrast to the primary cancer, a significantly increased frequency of the metastatic prostate cancer cells in bone exhibited homogeneous expression of E-cadherin and beta-catenin in 12 of 17 (71%) of the cases. A statistically significant association was observed between the overexpression of both proteins and the metastatic prostate cancer cells in bone (Fisher's exact P < 0.001).

CONCLUSIONS

The result of the study demonstrated for the first time that the membranous overexpression of E-cadherin and beta-catenin are significantly associated with the metastatic prostate cancer cells in bone and that the high frequency of expression suggest their involvement in the intercellular adhesion of the metastatic cells in bone.

Bench to bedside and back again: molecular mechanisms of alpha-catenin function and roles in tumorigenesis

The cadherin/catenin complex, comprised of E-cadherin, beta-catenin and alpha-catenin, is essential for initiating cell-cell adhesion, establishing cellular polarity and maintaining tissue organization. Disruption or loss of the cadherin/catenin complex is common in cancer. As the primary cell-cell adhesion protein in epithelial cells, E-cadherin has long been studied in cancer progression. Similarly, additional roles for beta-catenin in the Wnt signaling pathway has led to many studies of the role of beta-catenin in cancer. Alpha-catenin, in contrast, has received less attention. However, recent data demonstrate novel functions for alpha-catenin in regulating the actin cytoskeleton and cell-cell adhesion, which when perturbed could contribute to cancer progression. In this review, we use cancer data to evaluate molecular models of alpha-catenin function, from the canonical role of alpha-catenin in cell-cell adhesion to non-canonical roles identified following conditional alpha-catenin deletion. This analysis identifies alpha-catenin as a prognostic factor in cancer progression.

Quantitative fluorescence imaging analysis for cancer biomarker discovery: application to beta-catenin in archived prostate specimens

The surprising disparity between the number of protein-encoding genes ( approximately 30,000) in the human genome and the number of proteins ( approximately 300,000) in the human proteome has inspired the development of translational proteomics aimed at protein expression profiling of disease states. Translational proteomics, which offers the promise of early disease detection and individualized therapy, requires new methods for the analysis of clinical specimens. We have developed quantitative fluorescence imaging analysis (QFIA) for accurate, reproducible quantification of proteins in slide-mounted tissues. The method has been validated for the analysis of beta-catenin in archived prostate specimens fixed in formalin. QFIA takes advantage of the linearity of fluorescence antibody signaling for tissue epitope content, a feature validated for beta-catenin in methacarn-fixed prostate specimens analyzed by reverse-phase protein array analysis and QFIA (r = 0.97). QFIA of beta-catenin in formaldehyde-fixed tissues correlated directly with beta-catenin content (r = 0.86). Application of QFIA in a cross-sectional study of biopsies from 42 prostate cancer (PC) cases and 42 matched controls identified beta-catenin as a potential field marker for PC. Receiver operating characteristic plots revealed that beta-catenin expression in the normal-appearing acini of cancerous glands identified 42% (95% confidence intervals, 26-57%) of cancer cases, with 88% (95% confidence intervals, 80-96%) specificity. The marker may contribute to a PC biomarker panel. In conclusion, we report the development and validation of a new method for fluorescence quantification of proteins in archived tissues and its application to archived specimens for an evaluation of beta-catenin expression as a biomarker for PC.

Co-culturing human prostate carcinoma cells with hepatocytes leads to increased expression of E-cadherin

Metastasis is a multi-step process wherein tumour cells detach from the primary mass, migrate through barrier matrices, gain access to conduits to disseminate, and subsequently survive and proliferate in an ectopic site. During the initial invasion stage, prostate carcinoma cells undergo epithelial–mesenchymal-like transition with gain of autocrine signalling and loss of E-cadherin, hallmarks that appear to enable invasion and dissemination. However, some metastases express E-cadherin, and we found close connections between prostate carcinoma cells and hepatocytes in a liver microtissue bioreactor. We hypothesise that phenotypic plasticity occurs late in prostate cancer progression at the site of ectopic seeding. Immunofluorescence staining for E-cadherin in co-cultures of hepatocytes and DU-145 prostate cancer cells revealed E-cadherin upregulation at peripheral sites of contact by day 2 of co-culture; E-cadherin expression also increased in PC-3 cells in co-culture. These carcinoma cells bound to hepatocytes in an E-cadherin-dependent manner. Although the signals by which the hepatocytes elicited E-cadherin expression remain undetermined, it appeared related to downregulation of epidermal growth factor receptor (EGFR) signalling. Inhibition of autocrine EGFR signalling increased E-cadherin expression and cell–cell heterotypic adhesion; further, expression of a downregulation-resistant EGFR variant prevented E-cadherin upregulation. These findings were supported by finding E-cadherin and catenins but not activated EGFR in human prostate metastases to the liver. We conclude that the term epithelial–mesenchymal transition only summarises the transient downregulation of E-cadherin for invasion with re-expression of E-cadherin being a physiological consequence of metastatic seeding.

15-Lipoxygenase 2 (15-LOX2) is a functional tumor suppressor that regulates human prostate epithelial cell differentiation, senescence, and growth (size)

15-Lipoxygenase 2 (15-LOX2) is the major mammalian lipoxygenase expressed in normal human adult prostate and its expression is decreased or lost in high-grade prostate intraepithelial neoplasia (HGPIN) and prostate cancer (PCa). Our recent work has demonstrated that (1) 15-LOX2 has multiple alternatively spliced isoforms and is a negative cell-cycle regulator in normal human prostate (NHP) epithelial cells; (2) 15-LOX2 in NHP cells is positively regulated by Sp1 and negatively regulated by Sp3; (3) 15-LOX2 in NHP cells may be partially involved in cell differentiation; (4) 15-LOX2 is cell-autonomously upregulated in cultured NHP cells and its induction is associated with NHP cell senescence; and (5) 15-LOX2 is a functional prostate tumor suppressor. Here we summarize these new findings to provide a concise view of the potential biological functions of 15-LOX2 in NHP cells and of its deregulation in PCa development.

p120-ctn: A nexus for contextual signaling via Rho GTPases

p120 catenin (p120) is the prototypic member of a subfamily of armadillo repeat domain proteins involved in intercellular adhesion. Recent evidence indicates that p120 associates with classical cadherins and regulates their stability. Ectopic p120 expression results in a variety of morphological effects, and promotes cell migration. There is now strong evidence that p120 acts, at least in part, through regulation of Rho GTPases. The data suggest that p120 may act as a signaling nexus, conveying messages from the cellular micro- and macro-environment to the cell's interior. By regulating Rho GTPases in a context-dependent manner p120 can exert profound effects on cellular responses from synaptic plasticity to vesicle trafficking, as well as regulate the motile vs. sessile, and possibly the proliferative vs. quiescent phenotype of epithelial cells. Here, we review the new evidence on the relationship of p120 to Rho GTPases, and discuss potential roles for the p120-Rho connection in normal and malignant cells.

Epigenetics of prostate cancer: beyond DNA methylation

Epigenetic mechanisms permit the stable inheritance of cellular properties without changes in DNA sequence or amount. In prostate carcinoma, epigenetic mechanisms are essential for development and progression, complementing, amplifying and diversifying genetic alterations. DNA hypermethylation affects at least 30 individual genes, while repetitive sequences including retrotransposons and selected genes become hypomethylated. Hypermethylation of several genes occurs in a coordinate manner early in carcinogenesis and can be exploited for cancer detection, whereas hypomethylation and further hypermethylation events are associated with progression. DNA methylation alterations interact with changes in chromatin proteins. Prominent alterations at this level include altered patterns of histone modification, increased expression of the EZH2 polycomb histone methyltransferase, and changes in transcriptional corepressors and coactivators. These changes may make prostate carcinoma particularly susceptible to drugs targeting chromatin and DNA modifications. They relate to crucial alterations in a network of transcription factors comprising ETS family proteins, the androgen receptor, NKX3.1, KLF, and HOXB13 homeobox proteins. This network controls differentiation and proliferation of prostate epithelial cells integrating signals from hormones, growth factors and cell adhesion proteins that are likewise distorted in prostate cancer. As a consequence, prostate carcinoma cells appear to be locked into an aberrant state, characterized by continued proliferation of largely differentiated cells. Accordingly, stem cell characteristics of prostate cancer cells appear to be secondarily acquired. The aberrant differentiation state of prostate carcinoma cells also results in distorted mutual interactions between epithelial and stromal cells in the tumor that promote tumor growth, invasion, and metastasis.

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.

The role of kallikrein-related peptidases in prostate cancer: potential involvement in an epithelial to mesenchymal transition

Several members of the kallikrein-related peptidase family of serine proteases have proteolytic activities that may affect cancer progression; however, the in vivo significance of these activities remains uncertain. We have demonstrated that expression of PSA or KLK4, but not KLK2, in PC-3 prostate cancer cells changed the cellular morphology from epithelial to spindle-shaped, markedly reduced E-cadherin expression, increased vimentin expression and increased cellular migration. These changes are indicative of an epithelial to mesenchymal transition (EMT), a process important in embryonic development and cancer progression. The potential novel role of kallikrein-related peptidases in this process is the focus of this brief review.

Clinical evaluation of E-cadherin expression and its regulation mechanism in epithelial ovarian cancer

E-cadherin plays an important role in maintaining tissue architecture. Loss of E-cadherin expression has often been associated with cancer metastasis. This study assessed the immuno-expression of E-cadherin and methylation of CDH1 and correlated them with clinical features in primary epithelial ovarian cancer. Moreover, epithelial ovarian cancer cell SKOV3 was used to explore the mechanism how the demethylating agent 5-Aza inhibited cancer metastasis. Of 80 patients with primary ovarian cancer, we found that decreased immunoexpression pattern of E-cadherin was associated with clinical stage, lymph node metastasis, and degree of differentiation. Methylation of CDH1 detected by MSP occurred frequently and was correlated with reduced expression of E-cadherin protein. 5-Aza treatment could lead to re-expression of functional E-cadherin, followed by decreased MMP-2 and MMP-9 activity and inhibition of cell invasion in SKOV3 cells. Therefore, we conclude that assessment of E-cadherin immunoreactivity or methylation of CDH1 may be a useful prognostic indicator in ovarian cancer, complementary to established prognostic factors. The mechanism underlying 5-Aza's anti-metastasis activity is associated with restored functional expression of E-cadherin and decreased MMPs activity. Correction of aberrant DNA methylation by 5-Aza may provide a new strategy for ovarian cancer prevention and therapy.

E-cadherin polymorphisms and haplotypes influence risk for prostate cancer

BACKGROUND

The E-cadherin (CDH1) gene has been implicated in prostate cancer (PCA) risk, however, the exact mechanism is unknown. Several polymorphisms, such as the C/A variant -160 base pairs from the transcription start site, in the CDH1 gene promoter region have been associated with cancer risk, mainly in European descent populations.

METHODS

We screened the entire coding region and 3.0 kilobases of the CDH1 promoter for polymorphisms in 48 African Americans using dHPLC. Twenty-one (21) polymorphisms were observed. Four polymorphisms, including -160C/A, were genotyped in a genetic association study using incident PCA cases (N = 427) and unaffected controls (N = 337) of similar age from three different ethnic groups consisting of African Americans, Jamaicans, and European Americans.

RESULTS

We observed a significantly higher frequency of the -160A allele among European American PCA patients (27.5%) compared to the control group (19.7%) (P = 0.04). More importantly, among men of European ancestry under the age of 65 who possess the -160 A allele there was over three times increased risk for prostate cancer (P = 0.05). Also, the AACT haplotype bearing the -160A allele was significantly associated with PCA in European Americans (P = 0.04).

CONCLUSIONS

Our data indicate that CDH1 likely is a low-penetrant PCA susceptibility gene, however, population differences in linkage disequilibrium within the CDH1 gene region may influence the effect of susceptibility alleles such as -160A.

Reduced p120ctn expression correlates with poor survival in patients with adenocarcinoma of the gastroesophageal junction

BACKGROUND AND OBJECTIVES

P120-catenin (p120ctn) is a member of the E-cadherin-catenin cell-cell adhesion complex. Impairment of one or more of the components of this complex is associated with tumorigenesis. The role of p120ctn in malignancy is not clear yet. We studied the in vivo expression and cellular localization of p120ctn in adenocarcinomas of the gastroesophageal junction.

METHODS

Immunohistochemical staining for p120ctn was performed on 96 tumor samples, 20 cases of Barretts metaplasia and 13 lymph node metastases. The relationship with pathological characteristics and patient survival was also assessed.

RESULTS

Loss of normal surface p120ctn expression was found in 4/20 (20%) Barretts metaplasia, in 65/96 (68%) tumors, and 11/13 (85%) lymph node metastases. Nuclear immunoreactivity for p120ctn was seen in five tumors. Loss of normal expression of p120ctn was associated with a higher tumor grade (P < 0.0001) but not with pTNM-stage. Reduced expression of p120ctn was correlated with poor survival (P = 0.0002). Cox regression analysis showed that p120ctn is an independent prognostic marker.

CONCLUSIONS

Abnormal p120ctn expression is frequently seen in adenocarcinomas of the gastroesophageal junction, and may be a useful as a prognostic marker in these tumors.

Interaction of nuclear receptors with the Wnt/beta-catenin/Tcf signaling axis: Wnt you like to know?

The cross-regulation of Wnt/beta-catenin/Tcf ligands, kinases, and transcription factors with members of the nuclear receptor (NR) family has emerged as a clinically and developmentally important area of endocrine cell biology. Interactions between these signaling pathways result in a diverse array of cellular effects including altered cellular adhesion, tissue morphogenesis, and oncogenesis. Analyses of NR interactions with canonical Wnt signaling reveal two broad themes: Wnt/beta-catenin modulation of NRs (theme I), and ligand-dependent NR inhibition of the Wnt/beta-catenin/Tcf cascade (theme II). Beta-catenin, a promiscuous Wnt signaling member, has been studied intensively in relation to the androgen receptor (AR). Beta-catenin acts as a coactivator of AR transcription and is also involved in co-trafficking, increasing cell proliferation, and prostate pathogenesis. T cell factor, a transcriptional mediator of beta-catenin and AR, engages in a dynamic reciprocity of nuclear beta-catenin, p300/CREB binding protein, and transcriptional initiation factor 2/GC receptor-interaction protein, thereby facilitating hormone-dependent coactivation and transrepression. Beta-catenin responds in an equally dynamic manner with other NRs, including the retinoic acid (RA) receptor (RAR), vitamin D receptor (VDR), glucocorticoid receptor (GR), progesterone receptor, thyroid receptor (TR), estrogen receptor (ER), and peroxisome proliferator-activated receptor (PPAR). The NR ligands, vitamin D(3), trans/cis RA, glucocorticoids, and thiazolidines, induce dramatic changes in the physiology of cells harboring high Wnt/beta-catenin/Tcf activity. Wnt signaling regulates, directly or indirectly, developmental processes such as ductal branching and adipogenesis, two processes dependent on NR function. Beta-catenin has been intensively studied in colorectal cancer; however, it is now evident that beta-catenin may be important in cancers of the breast, prostate, and thyroid. This review will focus on the cross-regulation of AR and Wnt/beta-catenin/Tcf but will also consider the dynamic manner in which RAR/RXR, GR, TR, VDR, ER, and PPAR modulate canonical Wnt signaling. Although many commonalities exist by which NRs interact with the Wnt/beta-catenin signaling pathway, striking cell line and tissue-specific differences require deciphering and application to endocrine pathology.