Alteration of beta-catenin expression in esophageal squamous-cell carcinoma

The Relationship between LRP6 and Wnt/β-Catenin Pathway in Colorectal and Esophageal Cancer

High expression of low-density lipoprotein receptor-related protein 6 (LRP6), a key component of the Wnt/β-catenin signaling pathway, is reported to be associated with malignant potential in some solid tumors including breast cancer and hepatocellular carcinoma. Few reports, however, have examined its function and clinical significance in colorectal cancers (CRC) demonstrating constitutive activation of Wnt signaling. Here, we compared the expression level and function of LRP6 in CRC with that of esophageal squamous cell carcinoma (ESCC) bearing few Wnt/β-catenin pathway mutations. On immunohistochemical staining, high LRP6 expression was noted in three of 68 cases (4.4%), and high β-catenin in 38 of 67 cases (56.7%) of CRC. High LRP6 expression was found in 21 of 82 cases (25.6%), and high β-catenin expression in 29 of 73 cases (39.7%) of ESCC. In our in vitro studies, LRP6 knockdown hardly changed Wnt signaling activity in CRC cell lines with mutations in Wnt signaling downstream genes. In contrast, in ESCC cell lines without Wnt signaling-related mutations, LRP6 knockdown significantly decreased Wnt signaling activity. LRP6 function may depend on constitutive activation of Wnt signaling.

Prediction of recurrence free survival for esophageal cancer patients using a protein signature based risk model

BACKGROUND

Biomarkers to predict the risk of disease recurrence in Esophageal squamous cell carcinoma (ESCC) patients are urgently needed to improve treatment. We developed proteins expression-based risk model to predict recurrence free survival for ESCC patients.

METHODS

Alterations in Wnt pathway components expression and subcellular localization were analyzed by immunohistochemistry in 80 ESCCs, 61 esophageal dysplastic and 47 normal tissues; correlated with clinicopathological parameters and clinical outcome over 86 months by survival analysis. Significant prognostic factors were identified by multivariable Cox regression analysis.

RESULTS

Biomarker signature score based on cytoplasmic β-catenin, nuclear c-Myc, nuclear DVL and membrane α-catenin was associated with recurrence free survival [Hazard ratio = 1.11 (95% CI = 1.05, 1.17), p < 0.001, C-index = 0.68] and added significant prognostic value over clinical parameters (p < 0.001). The inclusion of Slug further improved prognostic utility (p < 0.001, C-index = 0.71). Biomarker Signature Scoreslug improved risk classification abilities for clinical outcomes at 3 years, accurately predicting recurrence in 79% patients in 1 year and 97% in 3 years in high risk group; 73% patients within low risk group did not have recurrence in 1 year, with AUC of 0.76.

CONCLUSIONS

Our comprehensive risk model predictive for recurrence allowed us to determine the robustness of our biomarker panel in stratification of ESCC patients at high or low risk of disease recurrence; high risk patients are stratified for more rigorous personalized treatment while the low risk patients may be spared from harmful side effects of toxic therapy.

Relationship between apical junction proteins, gene expression and cancer

The apical junctional complex (AJC) is a cell-cell adhesion system present at the upper portion of the lateral membrane of epithelial cells integrated by the tight junction (TJ) and the adherens junction (AJ). This complex is crucial to initiate and stabilize cell-cell adhesion, to regulate the paracellular transit of ions and molecules and to maintain cell polarity. Moreover, we now consider the AJC as a hub of signal transduction that regulates cell-cell adhesion, gene transcription and cell proliferation and differentiation. The molecular components of the AJC are multiple and diverse and depending on the cellular context some of the proteins in this complex act as tumor suppressors or as promoters of cell transformation, migration and metastasis outgrowth. Here, we describe these new roles played by TJ and AJ proteins and their potential use in cancer diagnostics and as targets for therapeutic intervention.

Cleistanthin A inhibits the invasion of MDA-MB-231 human breast cancer cells: involvement of the β-catenin pathway

BACKGROUND

Cleistanthin A (CleA), a natural diphyllin glycoside, has been shown to suppress the invasion of cancer cells, but the underlying mechanisms remain unclear. Here, the inhibitory effect of CleA on the invasion of MDA-MB-231 human breast cancer cells was investigated, and the mechanisms involved were clarified.

METHODS

Cell viability was studied by MTT assay. The migration and invasion of MDA-MB-231 cells were assessed by wound healing assay and transwell assay, respectively. The enzymatic activity of matrix metalloproteinases (MMPs) was detected by gelatin zymography. mRNA and protein levels were detected by qRT-PCR and Western blotting, respectively. Nuclear translocation of β-catenin was observed by immunofluorescence and detected by Western blotting.

RESULTS

CleA effectively inhibited the migration and invasion of MDA-MB-231 cells and suppressed the expression and activation of MMP-2/9. Moreover, the expression and nuclear translocation of β-catenin were reduced by CleA treatment, as well as transcription of the Cyclin D1 and c-myc genes. In addition, the inhibitory effect of CleA on the β-catenin pathway was attributed to the promotion of β-catenin degradation by inhibition of GSK3β phosphorylation. When the phosphorylation of GSK3β was induced by LiCl, the inhibitory effect of CleA on the β-catenin pathway and the invasion of MDA-MB-231 cells were almost reversed.

CONCLUSION

CleA suppressed the invasion of MDA-MB-231 cells, likely through the β-catenin pathway.

The Role of Wnt/β-Catenin Signaling and K-Cadherin in the Regulation of Intraocular Pressure

Purpose

Wnt/β-catenin signaling in the trabecular meshwork (TM) is required for maintaining normal intraocular pressure (IOP), although the mechanism(s) behind this are unknown. We hypothesize that Wnt/β-catenin signaling regulates IOP via β-catenin's effects on cadherin junctions.

Methods

Nonglaucomatous primary human TM (NTM) cells were treated with or without 100 ng/ml Wnt3a, 1 μg/ml sFRP1, or both for 4 to 48 hours. Cells were immunostained for β-catenin, total cadherins, or cadherin isoforms. Membrane proteins or whole-cell lysates were isolated for Western immunoblotting and probed for cadherin isoforms. RNA was extracted for cDNA synthesis and qPCR analysis of cadherin expression. Some NTM cells were cultured on electric plates for cell impedance assays. Ad5.CMV recombinant adenoviruses encoding K-cadherin, and/or sFRP1 were injected into eyes of 4- to 6-month-old female BALB/cJ mice (n = 8–10). Conscious IOPs were assessed for 35 days.

Results

Upon Wnt3a treatment, total cadherin expression increased and β-catenin accumulated at the TM cell membrane and on processes formed between TM cells. qPCR showed that Wnt3a significantly increased K-cadherin expression in NTM cells (P < 0.01, n = 3), and Western immunoblotting showed that Wnt3a increased K-cadherin in NTM cells, which was inhibited by the addition of sFRP1. Cell impedance assays showed that Wnt3a treatment increased transcellular resistance and anti-K-cadherin siRNA decreased transcellular resistance (P < 0.001, n = 4–6). Our in vivo study showed that K-cadherin significantly decreased sFRP1-induced ocular hypertension (P < 0.05, n = 6). Western immunoblotting also showed that K-cadherin alleviated sFRP1-induced β-catenin decrease in mouse anterior segments.

Conclusions

Our results suggest that cadherins play important roles in the regulation of TM homeostasis and IOP via the Wnt/β-catenin pathway.

HMQ-T-F2 exert antitumour effects by upregulation of Axin in human cervical HeLa cells

Looking for novel, effective and less toxic therapies for cervical cancer is of significant importance. In this study, we reported that HMQ‐T‐F2(F2) significantly inhibited cell proliferation and transplantable tumour growth. Mechanistically, HMQ‐T‐F2 inhibited HeLa cell growth through repressing the expression and nuclear translocation of β‐catenin, enhancing Axin expression, as well as downregulating the Wnt downstream targeted proteins. Knock‐down of a checkpoint β‐catenin by siRNA significantly attenuated HeLa cell proliferation. Furthermore, XAV939, an inhibitor of β‐catenin, was used to treat HeLa cells and the results demonstrated that HMQ‐T‐F2 inhibited proliferation and migration via the inhibition of the Wnt/β‐catenin pathway.

Downregulation of MicroRNA-644a Promotes Esophageal Squamous Cell Carcinoma Aggressiveness and Stem Cell-like Phenotype via Dysregulation of PITX2

PURPOSE

We previously reported the oncogenic role of paired-like homeodomain 2 (PITX2) in esophageal squamous cell carcinoma (ESCC). In this study, we aimed to identify the miRNA regulators of PITX2 and the mechanism underlying the pathogenesis of ESCC.

EXPERIMENTAL DESIGN

Using miRNA profiling and bioinformatics analyses, we identified miR-644a as a negative mediator of PITX2 in ESCC. A series of in vivo and in vitro assays were performed to confirm the effect of miR-644a on PITX2-mediated ESCC malignancy.

RESULTS

ESCC cells and tissues expressed less miR-644a than normal epithelial controls. In patient samples, lower expression of miR-644a in ESCC tissues was significantly correlated with tumor recurrence and/or metastasis, such that miR-644a, PITX2, and the combination of the two were independent prognostic indicators for ESCC patient's survival (P < 0.05). Gain- and loss-of-function studies demonstrated that miR-644a inhibited ESCC cell growth, migration, and invasion in vitro and suppressed tumor growth and metastasis in vivo In addition, miR-644a dramatically suppressed self-renewal and stem cell-like traits in ESCC cells. Furthermore, the effect of upregulation of miR-644a was similar to that of PITX2 knockdown in ESCC cells. Mechanistic studies revealed that miR-644a attenuates ESCC cells' malignancy and stem cell-associated phenotype, at least partially, by inactivation of the Akt/GSK-3β/β-catenin signaling pathway through PITX2. Furthermore, promoter hypermethylation caused downregulation of miR-644a in ESCC.

CONCLUSIONS

Downregulation of miR-644a plays an important role in promoting both aggressiveness and stem-like traits of ESCC cells, suggesting that miR-644a may be useful as a novel prognostic biomarker or therapeutic target for the disease. Clin Cancer Res; 23(1); 298-310. ©2016 AACR.

Transcriptomic analyses of genes differentially expressed by high-risk and low-risk human papilloma virus E6 oncoproteins

Human papilloma virus is the causative agent for cervical cancer with 99 % of cervical cancer cases containing HPV. The high risk HPV-16, 18 and 31 are the major causative agents. The low risk HPV-6, 11 have been reported to cause penile, laryngeal, bronchogenic and oesophageal cancer. Since E6 oncoprotein is frequently over expressed in cancers, we did gene expression studies to compare between the E6 genes of high-risk (HPV18) or low-risk (HPV11)stably transfected in epithelial cell line EPC-2 or mock transfected with the basic vector pCDNA3.1. Microarray studies showed a total of 697 genes showing differential expression between the samples. Genes involved in several key cellular processes such as cell adhesion, angiogenesis, transcription regulation, cell cycle regulation and cell division showed altered expression between the samples. Gene Ontology mapping of 44 genes according cellular pathways revealed 13 pathways namely angiogenesis, alzhemier's, Wnt, p53, interleukin, TGF-β, cadherin, integrin, PI3-kinase, catennin, insulin, chemokine and G protein signalling pathways. The microarray results were confirmed by quantitative real-time PCR for some representative genes like IFI27, CTNNA1, OSMR, CYP1B1, TNFSF13, LAMA2 and COL5A3. Analysis of differentially expressed genes by high-risk and low-risk HPV E6 proteins might help in identification of potential biomarkers for diagnosis, progression and therapy of oesophageal cancer. The understanding of mechanisms of activation of these genes as well as the function of gene products will give a further insight into their roles in oesophageal cancer.

β-catenin in oral cancer: an update on current knowledge

β-Catenin is a multiple function protein. These functions derive from its interactions with other cell proteins, both on the cell membrane, in the cytoplasm and in the nucleus. β-Catenin forms a complex with the adhesion molecule E-cadherin, promoting cell-cell adhesion and thereby preventing the cell dissociation that is required for cancer invasion and progression mechanisms. There is also a dynamic pool of cytoplasmic β-catenin that serves as connection between the extracellular microenvironment and the nucleus. Cytoplasmic β-catenin acts as a transcription factor for the nucleus in the canonical Wnt pathway, activating the transcription of various genes. Structural or functional alterations of β-catenin can promote cancer progression. This review addresses the current knowledge on the implications of β-catenin in the development of oral cancer.

Downregulation of sFRP-2 by epigenetic silencing activates the β-catenin/Wnt signaling pathway in esophageal basaloid squamous cell carcinoma

Basaloid squamous cell carcinoma (BSCC) of the esophagus is a rare variant of typical squamous cell carcinoma (SCC) associated with poor survival. A characteristic feature is nuclear accumulation of β-catenin, without a mutation of the gene. We studied the methylation status of Wnt antagonist genes, such as secreted frizzled-related protein (sFRP) gene family members, Wnt inhibitory factor-1 (WIF-1), Dickkopf-1 (Dkk-1), and human Dapper protein-1 (HDPR-1), and alterations of the APC, Axin1, and Axin2 genes in 30 cases of esophageal BSCC. β-catenin and sFRP (sFRP-1, sFRP-2, sFRP-4, sFRP-5) protein expression was examined by immunohistochemistry. APC, Axin1, and Axin2 gene mutations were detected in 3, 2, and 2 cases, respectively, and 6 cases (20 %) harbored at least 1 alteration in these genes. Methylation of the sFRP-2 promoter region was observed in all cases, and methylation was frequent in sFRP-1 and sFRP-5, but infrequent in Dkk-1, WIF-1, sFRP-4, and HDPR-1. sFRP-2 expression was almost completely absent in 25 cases (83 %), consistent with the methylation status. Nuclear accumulation of β-catenin was observed in all cases. sFRP-5 expression was associated with a low nuclear β-catenin labeling index. These results show that sFRP-2 is a target gene of hypermethylation in esophageal BSCC and suggest that sFRP-2 might contribute to BSCC tumorigenesis through the Wnt/β-catenin signaling pathway.

Down-regulated desmocollin-2 promotes cell aggressiveness through redistributing adherens junctions and activating beta-catenin signalling in oesophageal squamous cell carcinoma

In contrast to the well-recognized loss of adherens junctions in cancer progression, the role of desmosomal components in cancer development has not been well explored. We previously demonstrated that desmocollin-2 (DSC2), a desmosomal cadherin protein, is reduced in oesophageal squamous cell carcinoma (ESCC), and is associated with enhanced tumour metastasis and poor prognosis. Here, we report that restoration of DSC2 in ESCC cells impeded cell migration and invasion both in vitro and in vivo, whereas siRNA-mediated suppression of DSC2 expression increased cell motility. In E-cadherin-expressing ESCC cells, DSC2 restoration strengthened E-cadherin-mediated adherens junctions and promoted the localization of β-catenin at these junctions, which indirectly inhibited β-catenin-dependent transcription. These effects of DSC2 were not present in EC109 cells that lacked E-cadherin expression. ESCC patients with tumours that had reduced E-cadherin and negative DSC2 had poorer clinical outcomes than patients with tumours that lacked either E-cadherin or DSC2, implying that the invasive potential of ESCC cells was restricted by both DSC2 and E-cadherin-dependent junctions. Further studies revealed that DSC2 was a downstream target of miR-25. Enhanced miR-25 promoted ESCC cell invasiveness, whereas restoration of DSC2 abolished these effects. Collectively, our work suggests that miR-25-mediated down-regulation of DSC2 promotes ESCC cell aggressiveness through redistributing adherens junctions and activating beta-catenin signalling.

PITX2: a promising predictive biomarker of patients' prognosis and chemoradioresistance in esophageal squamous cell carcinoma

The paired-like homeodomain transcription factor 2 (PITX2), a downstream effector of wnt/β-catenin signaling, is well known to play critical role during normal embryonic development. However, the possible involvement of PITX2 in human tumorigenesis remains unclear. In this study, we extend its function in human esophageal squamous cell carcinoma (ESCC). The real-time PCR, Western blotting and immunohistochemistry (IHC) methods were applied to examine expression pattern of PITX2 in two different cohorts of ESCC cases treated with definitive chemoradiotherapy (CRT). Receiver operating characteristic (ROC) curve analysis was used to determine the cutoff point for PITX2 high expression in the training cohort. The ROC-derived cutoff point was then subjected to analyze the association of PITX2 expression with patients' survival and clinical characteristics in training and validation cohort, respectively. The expression level of PITX2 was significantly higher in ESCCs than that in normal esophageal mucosa. There was a positive correlation between PITX2 expression and clinical aggressiveness of ESCC. Importantly, high expression of PITX2 was observed more frequently in CRT resistant group than that in CRT effective group (p < 0.05). Furthermore, high expression of PITX2 was associated with poor disease-specific survival (p < 0.05) in ESCC. Then, the MTS, clonogenic survival fraction and cell apoptosis experiments showed that knockdown of PITX2 substantially increased ESCC cells sensitivity to ionizing radiation (IR) or cisplatin in vitro. Thus, the expression of PITX2, as detected by IHC, may be a useful tool for predicting CRT resistance and serves as an independent molecular marker for poor prognosis of ESCC patients treated with definite CRT.

Immunohistochemical and oncogenetic analyses of the esophageal basaloid squamous cell carcinoma in comparison with conventional squamous cell carcinomas

Basaloid squamous cell carcinoma of the esophagus is a rare variant of squamous cell carcinoma. We reviewed 878 cases of esophageal squamous cell carcinoma and detected 22 cases (3%) of basaloid squamous cell carcinoma. These tumors and stage-matched paired conventional squamous cell carcinomas were investigated for clinicopathologic features and immunoreactivity of cytokeratin subtypes, p53, B-cell lymphoma 2 (bcl-2), β-catenin, and epidermal growth factor receptor. Molecular aberrations in p53, CTNNB1 (the gene encoding β-catenin), and epidermal growth factor receptor (EGFR) were also determined. Patients with basaloid squamous cell carcinomas demonstrated a 5-year survival rate of 42%, significantly worse than those with well-differentiated squamous cell carcinoma (P<.01). Histologically, solid nests with central necrosis and a cribriform pattern were identified in almost all (≥95%) cases, and ductal differentiation was less frequent (45%) but associated with significantly better survival (P<.05). Compared with conventional squamous cell carcinomas, the basaloid squamous cell carcinomas were less immunoreactive for cytokeratin 14, cytokeratin 903, and membranous β-catenin (P<.01-.001) but more reactive for bcl-2, nuclear β-catenin, epidermal growth factor receptor, and Ki-67 (P<.05-.001). Direct sequencing showed mutations of p53 (36%), EGFR (14%), but not CTNNB1; fluorescent in situ hybridization detected amplification of the epidermal growth factor receptor gene (22%). In basaloid squamous cell carcinomas, low-level expression of cytokeratin 14/cytokeratin 903 and mutations of p53 and EGFR had a significant influence on worse survival (P<.05-.001). We conclude that the esophageal basaloid squamous cell carcinoma, a neoplasm with particularly aggressive biologic behavior, should be differentiated from conventional squamous cell carcinomas. In this context, immunohistochemical assessment of several markers might provide a useful adjunct diagnostic tool. Aberrations of p53 and epidermal growth factor receptor genes are possibly involved in progression of esophageal basaloid squamous cell carcinoma.

TP63 P2 promoter functional analysis identifies β-catenin as a key regulator of ΔNp63 expression

The ΔNp63 protein, a product of the TP63 gene that lacks the N-terminal domain, has a critical role in the maintenance of self renewal and progenitor capacity in several types of epithelial tissues. ΔNp63 is frequently overexpressed in squamous cell carcinoma (SCC) and in some other epithelial tumours. This overexpression may contribute to tumour progression through dominant-negative effects on the transcriptionally active (TA) isoforms of the p53 family (TAp63, TAp73 and p53), as well as through independent mechanisms. However, the molecular basis of ΔNp63 overexpression is not fully understood. Here, we show that the expression of ΔNp63 is regulated by the Wnt/β-catenin pathway in human hepatocellular carcinoma (HCC) and SCC cell lines. This regulation operates in particular through TCF/LEF sites present in the P2 promoter of TP63. In addition, we show that ΔNp63 and β-catenin are frequently coexpressed and accumulated in oesophageal SCC, but not in HCC. These results suggest that activation of the β-catenin pathway may contribute to overexpression of ΔNp63 during tumour progression, in a cell type-specific manner.

Prognostic relevance of β-catenin expression in T2-3N0M0 esophageal squamous cell carcinoma

AIM: To study the expression of β-catenin in esophageal squamous cell carcinoma (ESCC) at stage T2-3N0M0 and its relation with the prognosis of ESCC patients.

METHODS: Expression of β-catenin in 227 ESCC specimens was detected by immunohistochemistry (IHC). A reproducible semi-quantitative method which takes both staining percentage and intensity into account was applied in IHC scoring, and receiver operating characteristic curve analysis was used to select the cut-off score for high or low IHC reactivity. Then, correlation of β-catenin expression with clinicopathological features and prognosis of ESCC patients was determined.

RESULTS: No significant correlation was observed between β-catenin expression and clinicopathological parameters in terms of gender, age, tumor size, tumor grade, tumor location, depth of invasion and pathological stage. The Kaplan-Meier survival curve showed that the up-regulated expression of β-catenin indicated a poorer post-operative survival rate of ESCC patients at stage T2-3N0M0 (P = 0.004), especially of those with T3 lesions (P = 0.014) or with stage IIB diseases (P = 0.007). Multivariate analysis also confirmed that β-catenin was an independent prognostic factor for the overall survival rate of ESCC patients at stage T2-3N0M0 (relative risk = 1.642, 95% CI: 1.159-2.327, P = 0.005).

CONCLUSION: Elevated β-catenin expression level may be an adverse indicator for the prognosis of ESCC patients at stage T2-3N0M0, especially for those with T3 lesions or stage IIB diseases.

beta-Catenin/TCF pathway plays a vital role in selenium induced-growth inhibition and apoptosis in esophageal squamous cell carcinoma (ESCC) cells

Epidemiological and experimental studies have indicated selenium could reduce the risk of some cancers. In our present study, growth inhibition and apoptosis were detected upon methylseleninic acid (MSA) treatment in human esophageal squamous cell carcinoma cell lines EC9706 and KYSE150. MSA reduced beta-catenin protein levels, while there was no significant change observed on transcriptional levels. Moreover, we found MSA accelerated the degradation of beta-catenin and activated glycogen synthase kinase 3beta (GSK-3beta). Some targets of beta-catenin/TCF pathway and apoptosis-related genes altered after MSA treatment. Notably, utilizing the inducible 293-TR/beta-catenin cell line, we found the apoptotic phenotypes induced by MSA were partially reversed by the overexpression of beta-catenin. Overall, our data indicate the effects induced by MSA in ESCC cells may act on the inhibition of beta-catenin/TCF pathway.

WNT-5A, but not matrix metalloproteinase 3 or beta-catenin protein, expression is related to early stages of lip carcinogenesis

BACKGROUND

Oncogenic Wnt/beta-catenin signaling occurs in numerous types of cancers, but little is known about the role of the Wnt protein family member, WNT-5A, in lip carcinogenesis. The aim of this study was to investigate WNT-5A, beta-catenin, and matrix metalloproteinase (MMP)-3 protein expression in actinic cheilitis (AC), and lip squamous cell carcinoma (LSCC).

METHODS

Twenty-one cases of AC, and fifty-one cases of LSCC were analyzed, with normal lip mucosa used as a control. Qualitative and semi-quantitative analyses of WNT-5A, beta-catenin, and MMP-3 immunostaining pattern and cellular distribution were performed.

RESULTS

WNT-5A was observed in more than 50% of the cells, scattered in all layers of AC, in contrast to the absence of immunostaining in normal lip mucosa. AC presented a higher level of WNT-5A expression than LSCC (P = 0.0289, Fisher test), while MMP-3 immunoexpression was statistically more significant in LSCC than in AC (P = 0.0285, Fisher test). Immunolabeling of beta-catenin protein was differentially distributed between samples; the majority of AC cases (61.90%) demonstrated a membranous-cytoplasmic pattern, while a considerable number of LSCC cases (29.41%) revealed a cytoplasmic pattern, instead of the usual membranous pattern.

CONCLUSIONS

The present results suggest that WNT-5A may be an important marker during initial events of AC malignant transformation, in which non-canonical and canonical Wnt/beta-catenin signaling pathways could be involved. Additionally, WNT-5A might recruit other events in LSCC, such as MMP-3 protein synthesis, as its presence is increased in established malignant processes without beta-catenin dependency.

Gene silencing of beta-catenin by RNAi inhibits cell proliferation in human esophageal cancer cells in vitro and in nude mice

beta-Catenin, which is frequently overexpressed in a variety of human cancers including esophageal cancer, mediates cancer cell proliferation and tumor growth. In the present study, we used a human U6 promoter-driven DNA-template approach to induce short hairpin RNA (shRNA)-triggered RNA interference to silence beta-catenin gene expression in human esophageal squamous cell carcinoma cell line Eca-109, and then evaluated its effects on the proliferation and growth of tumor cells in vitro and in nude mice. beta-Catenin expression levels decreased markedly in Eca-109 cells transfected with a plasmid expressing shRNA for beta-catenin. Downregulation of beta-catenin was concomitantly accompanied by reduction of cyclin D1, colony formation, and growth inhibition of Eca-109 cells in vitro. The mechanism appears to be the G0/G1 phase arrest but not induction of apoptosis. In vivo, treatment of Eca-109 cells with beta-catenin shRNA greatly impeded tumor growth in nude mice. We conclude that plasmid vector-mediated beta-catenin RNA interference holds great promise as a novel treatment on human esophageal cancer with beta-catenin overexpression.

Screening of tissue microarrays for ubiquitin proteasome system components in tumors

The turnover of key proteins that mediate development, cellular proliferation, and a host of essential biological processes is controlled by the ubiquitin proteasome system (UPS). In several well-studied examples, notably in the cell cycle, regulatory proteins that control ubiquitin-dependent destruction are themselves substrates of the UPS, creating a multilayered system to ensure precise and dynamic control of protein stability. UPS regulators controlled at the level of protein stability--including the F-box protein Skp2 and the VHL protein (substrate adapter proteins for multicomponent E3 ubiquitin ligases)-- seem to be misregulated in tumors. In these cases, especially, measuring levels of critical regulatory and target proteins will often present a more biologically meaningful picture than examining relative mRNA levels, which do not always reflect corresponding protein levels. Tissue microarrays (TMAs) allow simultaneous screening of large numbers of tumors for expression of specific proteins by immunohistochemical staining of a single microscope slide prepared from a TMA paraffin block. Replicate slides prepared from the same block can be immunostained for multiple proteins functioning in a related pathway, and a semiquantitative protein expression profile for a given subset of UPS pathway components, or other subsets of proteins of interest, can be assembled. Protein expression profiles of individual tumors or tissue types can be compared and visualized by hierarchical clustering methods. These expression profiles may be used as screening tools to investigate the relative abundance of components of a biochemical pathway in tumors or other tissues. TMAs have an exciting future as tools for basic research, diagnostic pathology, and drug targeting. In this article, we provide an introduction to the use of TMAs to study the expression of UPS component proteins and substrates in tumors by immunohistochemistry.

Aberrant nuclear localization of beta-catenin without genetic alterations in beta-catenin or Axin genes in esophageal cancer

Background

β-catenin is a multifunctional protein involved in two apparently independent processes: cell-cell adhesion and signal transduction. β-catenin is involved in Wnt signaling pathway that regulates cellular differentiation and proliferation. In this study, we investigated the expression pattern of β-catenin and cyclin D1 using immunohistochemistry and searched for mutations in exon 3 of the β-catenin gene and Axin gene in esophageal squamous cell carcinoma.

Materials and methods

Samples were obtained from 50 esophageal cancer patients. Immunohistochemical staining for β-catenin and cyclin D1 was done. Mutational analyses of the exon3 of the β-catenin gene and Axin gene were performed on tumors with nuclear β-catenin expression.

Results

Four (8%) esophageal cancer tissues showed high nuclear β-catenin staining. Overexpression of cyclin D1 was observed in 27 out of 50 (54%) patients. All four cases that showed nuclear β-catenin staining overexpressed cyclin D1. No relationship was observed between the expression pattern of β-catenin and cyclin D1 and age, sex, tumor size, stage, differentiation grade, lymph node metastasis, response to chemotherapy, or survival. No mutational change was found in β-catenin exon 3 in the four cases with nuclear β-catenin staining. Sequencing analysis of the Axin cDNA revealed only a splicing variant (108 bp deletion, position 2302–2409) which was present in the paired normal mucosa.

Conclusion

A fraction of esophageal squamous cell carcinomas have abnormal nuclear accumulation of β-catenin accompanied with increased cyclin D1 expression. Mutations in β-catenin or axin genes are not responsible for this abnormal localization of β-catenin.

Microsatellite analysis of the APC gene and immunoexpression of E-cadherin, catenin, and tubulin in esophageal squamous cell carcinoma

The histological features that accompany the development and progression of solid tumors are known to be controlled by a distinct cascade of molecular events. One such event is the inactivation of tumor suppressor genes, such as the adenomatous polyposis coli (APC) gene. Disruption of the cadherin-catenin cell adhesion complex also plays a role in the initial steps of cancer invasion and metastasis whereas alterations in cell structural molecules, such as tubulin, may contribute to the cancer phenotype. The understanding of the status of these molecules in ESSC may provide novel markers that could impact on management of the disease. The present study examined alterations in the microsatellite sequence of the APC gene via fluorescent-based polymerase chain reaction in 100 cases of primary esophageal squamous cell carcinoma. In addition, the expression of E-cadherin, alpha- and beta-catenin, and alpha- and beta-tubulin was analyzed using immunohistochemistry. These data were then statistically compared with each other as well as the relevant clinicopathologic data. Although the APC markers (D5S210, D5S346, D5S299, and D5S82) tested did show an overall high frequency of allelic imbalance/loss of heterozygosity (62.48%) and microsatellite instability (41.27%), they did not show prognostic significance in the study cohort and were not correlated with the immunohistochemical data. The tubulin proteins showed no significant change in expression in the tumor tissue The decreased immunoreactivity of E-cadherin was statistically correlated with the presence of lymph node metastases (P = .0180). Although alpha- and beta-catenin as well as E-cadherin showed no direct prognostic value, E-cadherin may warrant further investigation as an indirect prognostic indicator by allowing more accurate prediction of lymph node metastases.

beta-Catenin splice variants and downstream targets as markers for neoplastic progression of esophageal cancer

This study characterizes the frequency of exon 3 CTNNB1 mutations and compares the expression of CTNNB1 transcript variants and downstream targets MYC and WAF1 (p21) across the neoplastic progression of esophageal squamous cell carcinomas (ESCCs). Mutational analysis was performed on 56 tumors and corresponding germline DNA, using primers to exon 3 of CTNNB1 and SSCP DNA sequencing gels. Quantitative Real Time RT-PCR was performed on 45 foci representing the histological spectrum from normal to invasive cancer, using specific primer sets for alternative splice variants that differ by the presence (16A) or absence (16B) of a 159-bp noncoding segment of exon 16 of CTNNB1, in conjunction with downstream targets MYC and WAF1. Two unique mutations were identified, S37F in the SxxxS repeat region, and a germline polymorphism, T59A. Thus, mutation of CTNNB1 exon 3 is a rare event in this population. RT-PCR analysis successfully confirmed the presence of both beta-catenin splice variants in histologically normal and preneoplastic squamous epithelium, and invasive tumors of the esophagus, and identified a significant reduction in the 16A/16B ratio (P = 0.014) and an accompanying significant increase in the MYC/WAF1 expression ratio (P = 0.001) with progression from normal mucosa to dysplasia. This represents the first identification of two CTNNB1 transcripts in histologically "normal" esophageal squamous cells, squamous dysplasia, and invasive ESCC. These results show an increase in the minor mRNA (16B) isoform and changes in the expression of downstream markers consistent with increased transcription during the histological progression from normal to squamous dysplasia.

Cyclin A and beta-catenin expression in actinic keratosis, Bowen's disease and invasive squamous cell carcinoma of the skin

BACKGROUND

Actinic keratosis (AK) has been defined as a precancerous lesion or an early phase in the evolution of squamous cell carcinoma (SCC) and histological changes seen in the individual cells of an AK are indistinguishable from those seen in SCC, which invade the dermis. Cyclin A is an increasingly utilized proliferation marker that has functions in both S phase (DNA replication) and initiation of mitosis, whereas alterations of beta-catenin, the molecule involved in cell-cell adhesion and in signalling transduction, could promote invasive and proliferative capacities of malignant tumours.

OBJECTIVES

To determine cyclin A and beta-catenin expression pattern in cutaneous SCC and in in situ lesions classified as keratinocytic intraepidermal neoplasia (KIN) and, using traditional terms, as AK and Bowen's disease (BD), and to analyse it in relation to SCC differentiation, diameter and thickness.

METHODS

Immunohistochemical staining was performed on 110 formalin-fixed paraffin-embedded tissue samples with the streptavidin-biotin technique using antibodies to cyclin A and beta-catenin. On histological examination, 53 lesions were diagnosed as AK, 16 as BD and 41 as SCC-11 well differentiated (WD), 16 moderately differentiated (MD) and 14 poorly differentiated (PD). Using KIN classification, 22 lesions were KIN1, 23 were KIN2 and 24 were KIN3. For cyclin A, distribution and labelling index (LI), and for beta-catenin, level of membranous staining and presence of aberrant (nuclear/cytoplasmic) localization were examined.

RESULTS

Diffuse cyclin A presence was observed more frequently in BD than in AK (P < 0.0001) or SCC (P = 0.0002), and in SCC-PD compared with SCC-WD (P < 0.0001) or SCC-MD (P = 0.0003). Differences between KIN3 and KIN2, as well as KIN3 and KIN1 lesions, were statistically significant (P < 0.0001), and the same result appeared when KIN1 and KIN2 cases were grouped and compared with those of KIN3 (P < 0.0001). Cyclin A LI was significantly lower (P < 0.05) in AK than in BD or SCC, but no difference between BD and SCC was found, and LI in BD was even higher than in SCC-WD or SCC-MD, while analysis regarding SCC differentiation and KIN classification revealed the same correlation as for the cyclin A distribution. Reduced or absent beta-catenin membranous staining was found in 90 cases (81.8%), more often in SCC than in AK (P = 0.03) or in AK and BD grouped together (P = 0.02). There was no statistical difference between SCCs of various level of differentiation, or between different KIN grades. Diffuse loss of membranous beta-catenin staining showed 36 lesions (32.7%), more frequently SCC than AK (P = 0.003) or AK and BD grouped (P = 0.006), as well as SCC-PD compared with SCC-WD (P = 0.01) and SCC-MD (P = 0.03), whereas all KIN comparisons remained nonsignificant. Aberrant beta-catenin cellular localization demonstrated 28 lesions (25.5%), most often in the basal or peripheral parts and in the lesions with diffuse beta-catenin loss (P = 0.009), but revealed no correlation with the histological type, SCC level of differentiation or KIN grades. Diffuse loss of membranous beta-catenin staining was found to be significantly more frequent in SCC thicker than 4 mm (P = 0.03), while all other comparisons between cyclin A or beta-catenin with the tumour size remained nonsignificant. Cyclin A LI was higher in cases with diffuse loss of membranous staining (P = 0.001) or with aberrant cellular localization of beta-catenin (P = 0.002).

CONCLUSIONS

Cyclin A LI showed greater difference between AK and BD than between BD and SCC, suggesting that increased proliferation (measured by cyclin A LI) characterizes progression of in situ lesions from AK to BD, whereas reduced beta-catenin expression separates more clearly SCC from the in situ lesions. Diffuse pattern of loss of membranous beta-catenin staining correlated better with the type of lesion, SCC differentiation and tumour size than reduced expression in general or aberrant cellular localization of beta-catenin. KIN classification does not seem to be supported by our findings, except when KIN1 and KIN2 lesions (in situ, partial thickness) are grouped.

Mutations of the APC, beta-catenin, and axin 1 genes and cytoplasmic accumulation of beta-catenin in oral squamous cell carcinoma

PURPOSE

The Wnt pathway is involved in carcinogenesis and three regulatory genes of the Wnt pathway, APC, beta-catenin and Axin are mutated in some primary human cancers. Mutations in these genes can impair the down regulation of beta-catenin, which results in the stabilization of beta-catenin, accumulation of free beta-catenin and subsequent activation of the Wnt pathway. To clarify the genetic alterations of components of the Wnt pathway in oral squamous cell carcinoma (SCC), we examined mutations in the APC, beta-catenin and Axin genes and subcellular localization of beta-catenin.

METHODS

20 oral SCC tissues and four cell lines derived from oral SCC were used. Mutational analysis was performed by a single-strand conformation polymorphism (SSCP) method and direct sequencing analysis. The samples were also examined by immunohistochemical staining and immunoblot analysis.

RESULTS

In 3 of 4 cell lines, mutations were observed in the APC and Axin1 genes without amino acid substitutions. In a clinical sample, a mutation in the Axin1 gene was detected; a T insertion at codon 250 resulted in the formation of a stop codon at codon 259. In addition, cytoplasmic accumulation of beta-catenin was observed in 3 (75%) of 4 cell lines and 18 (90%) of 20 cancer tissue samples.

CONCLUSION

The Axin1 gene may be one of the mutational target in oral SCC. In addition, the cytoplasmic accumulation of beta-catenin is a common characteristic of oral SCC, but is not closely associated with mutational alterations in the APC, beta-catenin and Axin1 genes.

Role of cell adhesion signal molecules in hepatocellular carcinoma cell apoptosis

AIM: Cell adhesion molecules and their signal molecules play a very important role in carcinogenesis. The aim of this study is to elucidate the role of these molecules and the signal molecules of integrins and E-cadherins, such as (focal adhesion kinase) FAK, (integrin linked kinase) ILK, and β-catenin in hepatocellular carcinoma cell apoptosis.

METHODS: We first synthesized the small molecular compound, S-(1,2-dichlorovinyl)-L-cysteine (DCVC), and identified it, by element analysis and ¹H NMR. To establish the apoptosis model of the SMMC-7721 hepatocellular carcinoma cell, we treated cells with DCVC in EBSS for different concentrations or for various length times in the presence of 20 μmol/L N,N’-diphenyl-p-phenylenediamine, which blocks necrotic cell death and identified this model by flow cytometry and DNA ladder. Then we studied the changes of FAK, ILK, β-catenin, and PKB in this apoptotic model by Western blot.

RESULTS: We found that the loss or decrease of cell adhesion signal molecules is an important reason in apoptosis of SMMC-7721 hepatocellular carcinoma cell and the apoptosis of SMMC-7721 cell was preceded by the loss or decrease of FAK, ILK, PKB, and β-catenin or the damage of cell-matrix and cell-cell adhesion.

CONCLUSION: Our results suggested that the decrease of adhesion signal molecules, FAK, ILK, PKB, and β-catenin, could induce hepatocellular carcinoma cell apoptosis.

Accumulation of cytoplasmic beta-catenin correlates with reduced expression of E-cadherin, but not with phosphorylated Akt in esophageal squamous cell carcinoma: Immunohistochemical study

Accumulation of beta-catenin in cytoplasm occurs frequently during the pathogenesis of esophageal squamous cell carcinoma (ESCC). The mechanism leading to this alteration, however, is largely unknown. In the present study, immunohistochemistry was performed for beta-catenin, E-cadherin and Ser473 phosphorylated Akt (P-Akt) in 44 tissue samples of ESCC and corresponding normal esophageal epithelium. Exon 3 of the beta-catenin gene was analyzed by using single-strand conformation polymorphism and direct sequencing. In addition to the reduced expression of E-cadherin and membranous beta-catenin observed in 65.9% and 68% of ESCC tested, respectively, cytoplasmic accumulation of beta-catenin was also detected in 68% (30/44) cases. However, only two cases were found to have the same beta-catenin gene mutation. The data showed that cytoplasmic accumulation of beta-catenin was significantly associated with reduced expression of E-cadherin (P < 0.05) and that of membranous beta-catenin (P < 0.05). Furthermore, cytoplasmic beta-catenin was correlated significantly with lymph node metastasis (P < 0.05). In contrast, although strong staining of P-Akt occurred in 14 of 44 cases (32%), there was no significant correlation between the positive staining of P-Akt and cytoplasmic beta-catenin. Taken together these results suggest that the lost membranous beta-catenin might translocate to cytoplasm depending on reduced expression of E-cadherin, while Akt seems unlikely to play a role in this process.

Overexpression of human pituitary tumor transforming gene (hPTTG), is regulated by beta-catenin /TCF pathway in human esophageal squamous cell carcinoma

Overexpression of human pituitary tumor transforming gene (PTTG) is wildly detected in many tumors, including esophageal cancer. Besides overexpression of PTTG in esophageal squamous cell carcinoma (ESCC) tissues and cells, we detected accumulation of cytoplasmic beta-catenin in ESCC. In our study, a putative TCF4-binding element (TBE) was identified in PTTG promoter region. The activity of PTTG promoter containing the TBE was activated by S37Abeta-catenin and inhibited by dominant-negative TCF. Furthermore, the activation by S37Abeta-catenin was mostly abrogated among PTTG promoter region without the TBE or with a mutant one. By using biotin-streptavidin pull-down assay, we also found that the TBE among PTTG promoter bound to TCF-4 protein. Moreover, levels of PTTG mRNA and protein were increased by S37Abeta-catenin. Finally, it is noticeable that we detected a correlation between beta-catenin localization and PTTG expression in 69 primary ESCC (p<0.01). In brief, our study shows that overexpression of PTTG in ESCC is likely due to the activation of beta-catenin/WNT signaling. As a target gene of beta-catenin/TCF pathway, PTTG may play an important role in tumorigenesis of human ESCC.

E6/E7 proteins of HPV type 16 and ErbB-2 cooperate to induce neoplastic transformation of primary normal oral epithelial cells

Head and neck squamous cell carcinomas (HNSCC) are characterized by a marked propensity for local invasion and spread to cervical lymph nodes, with distant metastases developing in 30-40% of cases. HPV-16 is an important risk factor for HNSCC. How HPV enhances susceptibility to HNSCC is not fully understood, but seems to involve cofactors. In this study, we examined the effect of the cooperation between HPV-16 and the tyrosine kinase receptor ErbB-2 on E-cadherin/catenin complex patterns and neoplastic transformation of human normal oral epithelial (NOE) cells. We report that overexpression of ErbB-2 or E6/E7 alone does not affect E-cadherin/catenin complex patterns nor does it induce cell transformation of NOE cells. In contrast, coexpression of E6/E7 and ErbB-2 downregulates E-cadherin and catenin expression. This is accompanied by cytoplasmic localization of E-cadherin, as well as nuclear translocation of alpha, beta, and gamma-catenins. Furthermore, we demonstrate that E6/E7 cooperate with overexpressed ErbB-2 to induce tumor formation in nude mice and to upregulate cyclin D1 and c-myc expression. Our data suggest that E6/E7 cooperate with ErbB-2 in head and neck carcinogenesis, at least in part, via the conversion of beta-catenin from a cell adhesion to a nuclear function, that is, to act as a potential transcriptional regulator. This conversion leads to the upregulation of cyclin D1, c-myc and other oncoproteins necessary for alteration of the E-cadherin/catenin complex and cell transformation of NOE cells.

Cadherins, catenins and APC in pleural malignant mesothelioma

Malignant mesothelioma is an aggressive disease of the pleura, and less commonly the peritoneum, with a very poor prognosis. The present study has examined the expression of cell adhesion molecules including cadherins, catenins, and APC in order to determine whether abnormal expression of components of the Wnt signalling pathway contribute to the variable phenotype of malignant mesothelioma. Sixty-three malignant mesotheliomas and nine cases of reactive mesothelial hyperplasia were analysed by immunohistochemistry for E-cadherin, N-cadherin, alpha-catenin, beta-catenin, and the C- and N-terminals of APC. In addition, DNA was extracted from formalin-fixed, paraffin wax blocks, and a 226 bp fragment of exon 3 of the beta-catenin gene was amplified, sequenced, and screened for activating mutations in the glycogen synthase kinase 3beta (GSK-3beta) phosphorylation targets. E-cadherin expression was detected in 48% of the epithelioid mesotheliomas but was observed in only 7% of sarcomatoid mesotheliomas. N-cadherin, alpha-catenin, beta-catenin, and the C- and N-terminals of APC did not show differential expression between the mesothelioma phenotypes. Abnormal nuclear localization of beta-catenin was demonstrated in 19% of mesotheliomas. Mutations of beta-catenin phosphorylation sites were not detected in any of the 62 mesotheliomas examined. Positive staining for the N-terminal of APC was seen in all of the cases of reactive mesothelial hyperplasia, as well as in all the mesotheliomas. Staining for the C-terminal of APC was negative in 23% mesotheliomas, despite being present in all the cases of reactive hyperplasia. The present study provides the first evidence that beta-catenin accumulates in the nucleus in malignant mesotheliomas. In addition, APC expression was altered in some mesotheliomas, suggesting that a truncated APC gene product may contribute to abnormal Wnt signalling and dysregulation of cell proliferation in malignant mesothelioma.

Redistribution of β-catenin in response to EGF and lithium signalling in human oesophageal squamous carcinoma cell lines

BACKGROUND

The β-catenin link between membrane-bound cadherins and the actin cytoskeleton regulates cell adhesion and consequently metastasis. Abnormal stabilisation of β-catenin enhances its transcriptional activities. Factors affecting β-catenin's functions are important in understanding metastatic diseases such as oesophageal squamous cell carcinoma (SCC).

RESULTS

In human oesophageal SCCs β-catenin localises predominantly to the plasma membrane. The presence of free β-catenin in the cytoplasm/nucleus was low. This indicates that β-catenin's activities are skewed towards cell-cell adhesion in these oesophageal SCCs. Exposure to EGF or Li alone, produced a slight increase in membrane concentrations but only Li induced β-catenin stabilisation in the cytoplasm. In combination, EGF and Li decreased membrane-associated β-catenin, concomitantly increasing cytoplasmic concentrations. Convergence of these signalling pathways appears to induce a β-catenin shift from the membrane into the cytoplasm.

CONCLUSION

Therefore, although the adhesive role of β-catenin appears to be intact, exogenous signals increase the stability of free β-catenin thereby reducing cell-cell adhesion in these tumours.

Expression of e-cadherin and β-catenin in human esophageal squamous cell carcinoma: relationships with prognosis

AIM: To elucidate the expression of E-cadherin and β-catenin correlating with its clinical outcome in patients with esophageal squamous cell carcinoma (ESCC), by analyzing their interrelationship with clinicopathological variables and their effects on progress and prognosis.

METHODS: Expression of E-cadherin and β-catenin was determined by SP immunohistochemical technique in patients with ESCC consecutively, their correlation with clinical characteristics was evaluated and analyzed by multivariate analysis.

RESULTS: The rate of expression of E-cadherin decreased to 66.03% (70/106) in ESCC and the protein level was negative correlated with histologic grade, tumor size, clinical staging, lymph node metastasis and venous invasion. Whereas the expression rate of β-catenin was reduced to 69.8% (74/106) and the level of protein expression correlated only with histologic grade. There obviously existed inverse correlation between level of E-cadherin protein and survival, especially in stage I, IIa, IIb (P = 0.0033), Patients with low-expressing tumors for β-catenin and non-expressing tumors for E-cadherin/β-catenin had lower survival period than those with normal-expressing ones (P = 0.0501 and P = 0.0080, respectively). Patients with diminished expression of E-cadherin as grade II or III had shorter survival period than those with normally expressing and grade I, no significance existed between grade I and grade II or III with respect to different status of E-cadherin expression. Furthermore, Correlation analysis showed level of E-cadherin correlated with that of β-catenin (P = 0.005). Cox proportional hazards model analysis suggested downregulation of E-cadherin was an important factor indicating poor prognosis.

CONCLUSION: As a probable independent prognostic factor, it correlates with overall and disease free survival period, expression of E-cadherin but not β-catenin may predict prognosis in patients with ESCC.

Identification of genes associated with head and neck carcinogenesis by cDNA microarray comparison between matched primary normal epithelial and squamous carcinoma cells

In order to identify genes involved in head and neck carcinogenesis, we compared the gene expression profile in matched primary normal epithelial cells and primary head and neck cancer cells from the same patients. A cDNA microarray analysis consisting of 12 530 human genes revealed significant changes in the expression of 213 genes, with 91 genes being up-regulated and 122 being down-regulated. This comprehensive list of genes includes those associated with signal transduction (growth factors), cell structure, cell cycle, transcription, apoptosis, and cell-cell adhesion. Further analysis of nine genes involved in cell-cell interaction, using Western blot and/or reverse transcription (RT)-PCR of four paired cell lines supported the reliability of our microarray analysis. More specifically, our study provides the first evidence that claudin-7 and connexin 31.1 are down-regulated in head and neck squamous cell carcinomas (HNSCC) compared to normal cells. These findings provide a large body of information regarding gene expression profiles associated with head and neck carcinogenesis, and also represent a source of potential targets for HNSCC prevention and/or therapeutics.

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

BACKGROUND

Catenin/E-cadherin complex proteins play an important role in cell-cell adhesion with decreased expression correlating with adverse prognostic variables in several human malignancies.

METHODS

Archival formalin fixed, paraffin embedded (FFPE) sections from 118 prostatic adenocarcinomas (PACs) were immunostained by an automated method (Ventana Medical Systems, Tuscon, AZ) using monoclonal antibodies to catenins alpha and beta, p120 CTN, and E-cadherin proteins. Immunoreactivity was semiquantitatively graded, and results correlated with traditional prognostic parameters. In a subset of 10 randomly selected cases, E-cadherin gene promoter methylation status was determined on FFPE tissues using sodium bisulfite/hydroquinone DNA modification and polymerase chain reaction (PCR) with methylation specific primers (CpG wiz E-cadherin methylation assay; Intergen Co., Purchase, NY).

RESULTS

Decreased expression of alpha-catenin (17%), beta catenin (4%), p120 CTN (45%), and E-cadherin (25%) proteins was noted in PACs with downregulation of each protein correlating with high tumor grade (P = 0.01-0.0001). In addition, p120 CTN and E-cadherin expression levels correlated with pathologic stage (P = 0.05; P = 0.02), aneuploidy (P = 0.001; P = 0.0001), and alpha-catenin with aneuploidy (P = 0.0001). p120 CTN loss also correlated with preoperative serum prostate specific antigen (P = 0.05). Two of 10 cases featured no evidence of E-cadherin gene promoter methylation by PCR and both cases retained expression of E-cadherin protein on immunohistochemistry. Of the 8 cases that showed E-cadherin methylation, 5 (68%) featured loss of expression of the protein on immunohistochemistry (P = 0.11). There was no correlation between E-cadherin methylation and adverse prognostic variables.

CONCLUSIONS

Decreased expression of catenin/E-cadherin complex cell adhesion proteins is associated with aggressive phenotype in prostatic adenocarcinoma. E-cadherin gene promote methylation is a common event in prostate carcinoma but does not appear to bear prognostic significance in the subset of cases analyzed.