E-cadherin expression is commonly downregulated by CpG island hypermethylation in esophageal carcinoma cells

Epigenetic modifications in esophageal cancer: An evolving biomarker

Esophageal cancer is a widespread cancer of the digestive system that has two main subtypes: esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EA). In the diverse range of cancer therapy schemes, the side effects of conventional treatments remain an urgent challenge to be addressed. Therefore, the pursuit of novel drugs with multiple targets, good efficacy, low side effects, and low cost has become a hot research topic in anticancer therapy. Based on this, epigenetics offers an attractive target for the treatment of esophageal cancer, where major mechanisms such as DNA methylation, histone modifications, non-coding RNA regulation, chromatin remodelling and nucleosome localization offer new opportunities for the prevention and treatment of esophageal cancer. Recently, research on epigenetics has remained at a high level of enthusiasm, focusing mainly on translating the basic research into the clinical setting and transforming epigenetic alterations into targets for cancer screening and detection in the clinic. With the increasing emergence of tumour epigenetic markers and antitumor epigenetic drugs, there are also more possibilities for anti-esophageal cancer treatment. This paper focuses on esophageal cancer and epigenetic modifications, with the aim of unravelling the close link between them to facilitate precise and personalized treatment of esophageal cancer.

Role of Cell-Cell Junctions in Oesophageal Squamous Cell Carcinoma

Cell-cell junctions comprise various structures, including adherens junctions, tight junctions, desmosomes, and gap junctions. They link cells to each other in tissues and regulate tissue homeostasis in critical cellular processes. Recent advances in cell-cell junction research have led to critical discoveries. Cell-cell adhesion components are important for the invasion and metastasis of tumour cells, which are not only related to cell-cell adhesion changes, but they are also involved in critical molecular signal pathways. They are of great significance, especially given that relevant molecular mechanisms are being discovered, there are an increasing number of emerging biomarkers, targeted therapies are becoming a future therapeutic concern, and there is an increased number of therapeutic agents undergoing clinical trials. Oesophageal squamous cell carcinoma (ESCC), the most common histological subtype of oesophageal cancer, is one of the most common cancers to affect epithelial tissue. ESCC progression is accompanied by the abnormal expression or localisation of components at cell-cell junctions. This review will discuss the recent scientific developments related to the molecules at cell-cell junctions and their role in ESCC to offer valuable insights for readers, provide a global view of the relationships between position, construction, and function, and give a reference for future mechanistic studies, diagnoses, and therapeutic developments.

ESCC ATLAS: A population wide compendium of biomarkers for Esophageal Squamous Cell Carcinoma

Esophageal cancer (EC) is the eighth most aggressive malignancy and its treatment remains a challenge due to the lack of biomarkers that can facilitate early detection. EC is identified in two major histological forms namely - Adenocarcinoma (EAC) and Squamous cell carcinoma (ESCC), each showing differences in the incidence among populations that are geographically separated. Hence the detection of potential drug target and biomarkers demands a population-centric understanding of the molecular and cellular mechanisms of EC. To provide an adequate impetus to the biomarker discovery for ESCC, which is the most prevalent esophageal cancer worldwide, here we have developed ESCC ATLAS, a manually curated database that integrates genetic, epigenetic, transcriptomic, and proteomic ESCC-related genes from the published literature. It consists of 3475 genes associated to molecular signatures such as, altered transcription (2600), altered translation (560), contain copy number variation/structural variations (233), SNPs (102), altered DNA methylation (82), Histone modifications (16) and miRNA based regulation (261). We provide a user-friendly web interface ( http://www.esccatlas.org , freely accessible for academic, non-profit users) that facilitates the exploration and the analysis of genes among different populations. We anticipate it to be a valuable resource for the population specific investigation and biomarker discovery for ESCC.

ESCC ATLAS: A population wide compendium of biomarkers for Esophageal Squamous Cell Carcinoma

Esophageal cancer (EC) is the eighth most aggressive malignancy and its treatment remains a challenge due to the lack of biomarkers that can facilitate early detection. EC is identified in two major histological forms namely - Adenocarcinoma (EAC) and Squamous cell carcinoma (ESCC), each showing differences in the incidence among populations that are geographically separated. Hence the detection of potential drug target and biomarkers demands a population-centric understanding of the molecular and cellular mechanisms of EC. To provide an adequate impetus to the biomarker discovery for ESCC, which is the most prevalent esophageal cancer worldwide, here we have developed ESCC ATLAS, a manually curated database that integrates genetic, epigenetic, transcriptomic, and proteomic ESCC-related genes from the published literature. It consists of 3475 genes associated to molecular signatures such as, altered transcription (2600), altered translation (560), contain copy number variation/structural variations (233), SNPs (102), altered DNA methylation (82), Histone modifications (16) and miRNA based regulation (261). We provide a user-friendly web interface ( http://www.esccatlas.org , freely accessible for academic, non-profit users) that facilitates the exploration and the analysis of genes among different populations. We anticipate it to be a valuable resource for the population specific investigation and biomarker discovery for ESCC.

E-cadherin: Its dysregulation in carcinogenesis and clinical implications

E-cadherin is a transmembrane glycoprotein which connects epithelial cells together at adherens junctions. In normal cells, E-cadherin exerts its tumour suppressing role mainly by sequestering β-catenin from its binding to LEF (Lymphoid enhancer factor)/TCF (T cell factor) which serves the function of transcribing genes of the proliferative Wnt signaling pathway. Despite the ongoing debate on whether the loss of E-cadherin is the cause or effect of epithelial-mesenchymal transition (EMT), E-cadherin functional loss has frequently been associated with poor prognosis and survival in patients of various cancers. The dysregulation of E-cadherin expression that leads to carcinogenesis happens mostly at the epigenetic level but there are cases of genetic alterations as well. E-cadherin expression has been linked to the cellular functions of invasiveness reduction, growth inhibition, apoptosis, cell cycle arrest and differentiation. Studies on various cancers have shown that these different cellular functions are also interdependent. Recent studies have reported a rapid expansion of E-cadherin clinical relevance in various cancers. This review article summarises the multifaceted effect E-cadherin expression has on cellular functions in the context of carcinogenesis as well as its clinical implications in diagnosis, prognosis and therapeutics.

Form follows function: Morphological and immunohistological insights into epithelial-mesenchymal transition characteristics of tumor buds

In cancer biology, the architectural concept "form follows function" is reflected by cell morphology, migration, and epithelial-mesenchymal transition protein pattern. In vivo, features of epithelial-mesenchymal transition have been associated with tumor budding, which correlates significantly with patient outcome. Hereby, the majority of tumor buds are not truly detached but still connected to a major tumor mass. For detailed insights into the different tumor bud types and the process of tumor budding, we quantified tumor cells according to histomorphological and immunohistological epithelial-mesenchymal transition characteristics. Three-dimensional reconstruction from adenocarcinomas (pancreatic, colorectal, lung, and ductal breast cancers) was performed as published. Tumor cell morphology and epithelial-mesenchymal transition characteristics (represented by zinc finger E-box-binding homeobox 1 and E-Cadherin) were analyzed qualitatively and quantitatively in a three-dimensional context. Tumor buds were classified into main tumor mass, connected tumor bud, and isolated tumor bud. Cell morphology and epithelial-mesenchymal transition marker expression were assessed for each tumor cell. Epithelial-mesenchymal transition characteristics between isolated tumor bud and connected tumor bud demonstrated no significant differences or trends. Tumor cell count correlated significantly with epithelial-mesenchymal transition and histomorphological characteristics. Regression curve analysis revealed initially a loss of membranous E-Cadherin, followed by expression of cytoplasmic E-Cadherin and subsequent expression of nuclear zinc finger E-box-binding homeobox 1. Morphologic changes followed later in this sequence. Our data demonstrate that connected and isolated tumor buds are equal concerning immunohistochemical epithelial-mesenchymal transition characteristics and histomorphology. Our data also give an insight in the process of tumor budding. While there is a notion that the epithelial-mesenchymal transition zinc finger E-box-binding homeobox 1-E-Cadherin cascade is initiated by zinc finger E-box-binding homeobox 1, our results are contrary and outline other possible pathways influencing the regulation of E-Cadherin.

Cribriform-morular variant of papillary thyroid carcinoma: a distinctive type of thyroid cancer

The aim of this systematic review is to study the features of cribriform-morular variant of papillary thyroid carcinoma (CMV-PTC) by analysing the 129 documented cases in the English literature. The disease occurred almost exclusively in women. The median age of presentation for CMV-PTC was 24 years. Slightly over half of the patients with CMV-PTC had familial adenomatous polyposis (FAP). CMV-PTC presented before the colonic manifestations in approximately half of the patients with FAP. Patients with FAP often have multifocal tumours in the thyroid. Microscopic examination of CMV-PTC revealed predominately cribriform and morular pattern of cancer cells with characteristic nuclear features of papillary thyroid carcinoma. Psammoma body is rare. On immunohistochemical studies, β-catenin is diffusely positive in CMV-PTC. The morular cells in CMV-PTC are strongly positive for CD10, bcl-2 and E-cadherin. Pre-operative diagnosis of CMV-PTC by fine-needle aspiration biopsy could be aided by cribriform architecture, epithelial morules and β-catenin immunostaining. Mutations of APC gene are found in the patients with CMV-PTC associated with FAP. In addition, mutations in CTNNB1, RET/PTC rearrangement and PI3K3CA mutations have been reported. BRAF mutation is negative in all CMV-PTC tested. Compared to conventional papillary thyroid carcinoma, CMV-PTC had a lower frequency of lymph node metastases at presentation (12%) and distant metastases (3%) as well as lower recurrence rates (8.5%) and patients' mortality rates (2%). To conclude, patients with CMV-PTC have distinctive clinical, pathological and molecular profiles when compared to conventional papillary thyroid carcinoma.

DNA Methylation Status of PAX1 and ZNF582 in Esophageal Squamous Cell Carcinoma

Hypermethylation of specific gene promoters is an important mechanism of carcinogenesis. A high frequency of promoter methylation of PAX1 and ZNF582 genes has been detected in cervical cancer. In the present study, we investigated the methylation status of PAX1 and ZNF582 genes in esophageal squamous cell carcinoma (ESCC) tissues. Tumor and paracancerous tissues were obtained from 14 ESCC patients. Genomic DNA was extracted from both tumor and paracancerous tissues, and the concentration of DNA were determined. DNA methylation analysis of PAX1 and ZNF582 genes was carried out using quantitative methylation-specific PCR. To assess the diagnostic performance of the two methylated genes for cancer detection, receiver operating characteristic (ROC) curves were generated. Sensitivities and specificities were tested at cut-offs obtained from the ROC curves. The methylation levels of both PAX1 and ZNF582 genes were significantly higher in tumor tissues compared to non-tumor paracancerous tissues. The methylation rates of PAX1 and ZNF582 in ESCC tumor and paracancerous tissues were 100% and 21.4% (p = 0.006), 85.7% and 0% (p < 0.001), respectively. The sensitivities and specificities of PAX1 and ZNF582 methylation for the detection of cancer were 100% and 85.7%, and 78.6% and 100%, respectively. The DNA methylation levels and frequencies of PAX1 and ZNF582 genes were markedly higher in ESCC tumor tissues compared to those in paracancerous tissues. Moreover, the conclusions were verified by using The Cancer Genome Atlas (TCGA) datasets. DNA methylation status of these two genes showed a relatively good sensitivity and specificity for the detection of ESCC tumors. This data suggests that DNA methylation testing holds a great promise for ESCC screening and warrants further prospective population-based studies.

Identification of Novel FAM134B (JK1) Mutations in Oesophageal Squamous Cell Carcinoma

Mutation of FAM134B (Family with Sequence Similarity 134, Member B) leading to loss of function of its encoded Golgi protein and has been reported induce apoptosis in neurological disorders. FAM134B mutation is still unexplored in cancer. Herein, we studied the DNA copy number variation and novel mutation sites of FAM134B in a large cohort of freshly collected oesophageal squamous cell carcinoma (ESCC) tissue samples. In ESCC tissues, 37% (38/102) showed increased FAM134B DNA copies whereas 35% (36/102) showed loss of FAM134B copies relative to matched non-cancer tissues. Novel mutations were detected in exons 4, 5, 7, 9 as well as introns 2, 4-8 of FAM134B via HRM (High-Resolution Melt) and Sanger sequencing analysis. Overall, thirty-seven FAM134B mutations were noted in which most (31/37) mutations were homozygous. FAM134B mutations were detected in all the cases with metastatic ESCC in the lymph node tested and in 14% (8/57) of the primary ESCC. Genetic alteration of FAM134B is a frequent event in the progression of ESCCs. These findings imply that mutation might be the major driving source of FAM134B genetic modulation in ESCCs.

Inhibition of human esophageal squamous cell carcinomas by targeted silencing of tumor enhancer genes: an overview

Esophageal cancer has been reported as the ninth most common malignancy and ranks as the sixth most frequent cause of death worldwide. Esophageal cancer treatment involves surgery, chemotherapy, radiation therapy, or combination therapy. Novel strategies are needed to boost the oncologic outcome. Recent advances in the molecular biology of esophageal cancer have documented the role of genetic alterations in tumorigenesis. Oncogenes serve a pivotal function in tumorigenesis. Targeted therapies are directed at the unique molecular signature of cancer cells for enhanced efficacy with low toxicity. RNA interference (RNAi) technology is a powerful tool for silencing endogenous or exogenous genes in mammalian cells. Related results have shown that targeting oncogenes with siRNAs, specifically the mRNA, effectively reduces tumor cell proliferation and induces apoptotic cell death. This article will briefly review studies on silencing tumor enhancer genes related to the induction of esophageal cancer.

The role of DNA methyltransferase 3b in esophageal squamous cell carcinoma

BACKGROUND

The identification of potential tumor markers can improve therapeutic planning and patient management. The objective of this study was to highlight the role of DNA methyltransferase 3b (DNMT3b) in esophageal squamous cell carcinoma (SCC).

METHODS

One hundred seventy-three esophageal SCC samples were analyzed using immunohistochemical staining to correlate the expression of DNMT3b with clinical outcome. Furthermore, a human esophageal SCC cell line, CE81T, was selected for cellular and animal experiments to investigate changes in tumor behavior and treatment response after the manipulation of DNMT3b expression.

RESULTS

The incidence of nuclear DNMT3b immunoreactivity in esophageal cancer specimens was significantly higher than in nonmalignant epithelium, and this incidence was linked positively to developing distant metastasis (56% in localized disease vs 80% in distant metastasis; P = .002). Furthermore, increased expression of DNMT3b was linked significantly to lower treatment response rates (P = .002) and reduced survival rates (P = .000). Inhibition of DNMT3b expression resulted in slower cellular proliferation, increased cell death, a less invasive capacity, and less epithelial-mesenchymal-transition changes. Moreover, DNMT3b silencing vectors sensitized esophageal cancer cells to irradiation and cisplatin treatment. The current results also indicated that constitutional activation of signal transducer and activator of transcription 3 (STAT3) signaling associated with inhibited expression of suppressor of cytokine signaling 3 (SOCS3) may be the mechanism underlying more aggressive tumor growth in DNMT3b-positive esophageal cancer.

CONCLUSIONS

DNMT3b was linked significantly to a poor prognosis for patients with esophageal cancer. Moreover, the current results indicated that targeting this enzyme may be a promising strategy for treating esophageal cancer, as evidenced by inhibited aggressive tumor behavior and treatment resistance.

Promoter methylation of tumor suppressor genes in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a prevalent and fatal cancer in China and other Asian countries. Epigenetic silencing of key tumor suppressor genes (TSGs) is critical to ESCC initiation and progression. Recently, many novel TSGs silenced by promoter methylation have been identified in ESCC, and these genes further serve as potential tumor markers for high-risk group stratification, early detection, and prognosis prediction. This review summarizes recent discoveries on aberrant promoter methylation of TSGs in ESCC, providing better understanding of the role of disrupted epigenetic regulation in tumorigenesis and insight into diagnostic and prognostic biomarkers for this malignancy.

Adherens junctions and cancer

Cadherins and catenins are the central cell-cell adhesion molecules in adherens junctions (AJs). This chapter reviews the knowledge concerning the role of cadherins and catenins in epithelial cancer and examines the published literature demonstrating the changes in the expression and function of these proteins in human cancer and the association of these changes with patient outcomes. The chapter also covers the mechanistic studies aiming at uncovering the significance of changes in cadherin and catenin expression in cancer and potential molecular mechanisms responsible for the causal role of AJs in cancer initiation and progression.

Serum soluble E-cadherin is a potential prognostic marker in esophageal squamous cell carcinoma

E-cadherin is a well-documented tumor suppressor with downregulated expression in many cancer types. Upon proteolytic cleavage, a soluble form of 80-kDa degradation fragment, known as soluble E-cadherin (s-Ecad), is present in circulation; its level in sera of cancer patients is significantly associated with metastasis, recurrence, and prognosis in some malignancies. The present study investigated the association of s-Ecad with clinicopathological characteristics of patients with esophageal squamous cell carcinoma (ESCC) and its prognostic significance. A cohort of 97 patients who underwent surgery alone (n= 56) or neoadjuvant chemoradiation therapy and surgery (CRT) (n= 41) was recruited for this study. Serum samples were collected at operation (surgery group) and pre- and post-CRT treatment (CRT group) for measurement of s-Ecad protein by enzyme linked immunosorbent assay. Serum s-Ecad levels were correlated with clinicopathological parameters as well as survival. Univariate analysis showed no significant relationship between serum s-Ecad level and clinicopathological parameters for all sets of samples. Survival analysis showed that in patients who had surgical resection only, those with s-Ecad levels equal to or below the median value survived significantly longer than those with levels above the median (median survival 25.6 vs. 14.1 months, P= 0.012). Multivariate analysis showed that pathological N stage, M stage, R category, and serum s-Ecad level were significant independent prognostic factors for ESCC patients who underwent surgery only. The hazard ratio for s-Ecad was 1.104 (95% CI: 1.026-1.187) and P= 0.008. Serum s-Ecad was detected in ESCC patients and its potential as an independent prognostic marker requires further investigation.

Demethylation of E-cadherin gene in nasopharyngeal carcinoma could serve as a potential therapeutic strategy

E-cadherin has been proven to be widely down-regulated and tightly associated with tumour invasion and metastasis in multiple human cancer types. Recent research demonstrated that aberrant methylation around gene promoter region attributes to E-cadherin silencing. However, the detailed information about this epigenetic inactivation in nasopharyngeal carcinoma (NPC) is rare. The aim of this study was to probe more into the basic mechanism of E-cadherin methylation in NPC and elucidate the application of demethylating agents to restore E-cadherin expression. To address this question, we initially studied E-cadherin methylation status in NPC primary tumours and cell lines by methylation-specific PCR, and compared it with E-cadherin expression. Methylated E-cadherin was detected in 13 of 20 (65%) NPC clinical specimens and 2 of 2 (100%) NPC cell lines (HNE-1 and CNE-2), which was inversely correlated with E-cadherin expression. The detailed methylation profile at individual CpGs within CpG island of E-cadherin promoter region was confirmed by bisulphite sequencing. E-cadherin gene could be demethylated and reactivated in HNE-1 and CNE-2 cells upon treatment with 5-aza-dC, a DNA demethylating agent. Our findings indicate that frequent aberrant methylation of E-cadherin may play an important role in downregulation of E-cadherin, and demethylation therapy could serve as a promising strategy for NPC patients. Furthermore, a high frequency of E-cadherin methylation (9/20, 45%) in peripheral blood of NPC patients suggests its potential clinical application as an early diagnostic or predictive marker.

Expression of esophageal cancer related gene 4 (ECRG4), a novel tumor suppressor gene, in esophageal cancer and its inhibitory effect on the tumor growth in vitro and in vivo

The ECRG4 gene was initially identified and cloned in our laboratory from human normal esophageal epithelium (GenBank accession no. AF325503). We revealed the expression of ECRG4 protein was downregulated in 68.5% (89/130) ESCC samples using tissue microarray. The low ECRG4 protein expression was significantly associated with regional lymph node metastasis, primary tumor size, and tumor stage in ESCC (p < 0.05). ECRG4 mRNA expression was downregulated in ESCC due to the hypermethylation in the gene promoter. The treatment with 5-aza-2'-deoxycytidine, which is a DNA methyltransferase inhibitor restored ECRG4 mRNA expression in ESCC cells. The result indicated that promoter hypermethylation may be 1 main mechanism leading to the silencing of ECRG4. The high expression of ECRG4 in patients with ESCC was associated with longer survival compared with those with low ECRG4 expression by Kaplan-Meier survival analysis (p < 0.05). ECRG4 protein was an independent prognostic factor for ESCC by multivariable Cox proportional hazards regression analysis (p < 0.05). The restoration of ECRG4 expression in ESCC cells inhibited cell proliferation, colony formation, anchorage-independent growth, cell cycle progression and tumor growth in vivo (p < 0.05). The transfection of ECRG4 gene in ESCC cells inhibited the expression of NF-kappaB and nuclear translocation, in addition to the expression of COX-2, a NF-kappaB target gene, was attenuated. Taken together, ECRG4 is a novel candidate tumor suppressor gene in ESCC, and ECRG4 protein is a candidate prognostic marker for ESCC.

The presence of aberrant DNA methylation in noncancerous esophageal mucosae in association with smoking history: a target for risk diagnosis and prevention of esophageal cancers

BACKGROUND

Esophageal squamous cell carcinomas (ESCCs) tend to have multiple primary lesions, and it is believed that they arise from background mucosae with accumulation of genetic/epigenetic alterations. In this study, the objective was to elucidate the effects of smoking and drinking on the accumulation of epigenetic alterations in background mucosae.

METHODS

Genes that are silenced in human ESCCs were searched for by treating 3 ESCC cell lines with the demethylating agent, 5-aza-2'-deoxycytidine and performing oligonucleotide microarrays. Methylation levels were analyzed by quantitative methylation-specific polymerase chain reaction analysis of 60 ESCCs and their corresponding background mucosae.

RESULTS

Forty-seven genes were identified as methylation-silenced in at least 1 of the 3 ESCC cell lines, and 14 of those genes (claudin 6 [CLDN6]; G protein-coupled receptor 158 [GPR158]; homeobox A9 [HOXA9]; metallothionein 1M [MT1M]; neurofilament, heavy polypeptide 200 kDa [NEFH]; plakophilin 1 [PKP1]; protein phosphatase 1, regulatory [inhibitor] subunit 14A [PPP1R14A]; pyrin domain and caspase recruitment domain containing [PYCARD]; R-spondin family, member 4 [RSPO4]; testis-specific protein, Y-encoded-like 5 [TSPYL5]; ubiquitin carboxyl-terminal esterase L1 [UCHL1]; zinc-finger protein 42 homolog [ZFP42]; zinc-finger protein interacting with K protein 1 homolog [ZIK1]; and zinc-finger and SCAN domain containing 18 [ZSCAN18]) were used as markers. In the background mucosae, methylation levels of 5 genes (HOXA9, MT1M, NEFH, RSPO4, and UCHL1) had significant correlations with smoking duration (rho=.268; P=.044; rho=.405; P=.002; rho=.285; P=.032; rho=.300; P=.024; and rho=.437; P=.001, respectively). In contrast, an inverse correlation between PYCARD methylation levels and alcohol intake was observed (rho=-.334, P=.025) among individuals with the inactive aldehyde dehydrogenase 2 (ALDH2) genotype.

CONCLUSIONS

The current results suggested that ESCCs developed from an epigenetic field for cancerization, which was induced by exposure to carcinogenic factors, such as tobacco smoking. The epigenetic field defect will be a novel target for risk diagnosis and prevention of ESCCs.

Hereditary diffuse gastric cancer and lost cell polarity: a short path to cancer

The mechanisms that underlie the initiation of human cancer are poorly understood. Here, we describe the development of hereditary diffuse gastric cancer and argue that it arises from the disruption of the regenerative processes that are inherent to all epithelial tissues. This model supports the cancer stem cell hypothesis, in which tumors contain a subpopulation of cells with the key stem cell characteristics of capacity for self renewal, differentiation and limitless replication. We argue that epigenetic modifications induced by common environmental and physiological pressures are able to initiate this disruption. The carcinogenic effects of these modifications are potentially reversible through the use of epigenetic therapies such as DNA demethylating agents and histone deacetylation inhibitors.

Association of CDH1 single nucleotide polymorphisms with susceptibility to esophageal squamous cell carcinomas and gastric cardia carcinomas

E-cadherin (CDH1) is a tumor suppressor involved in epithelial cell-cell interactions. Single nucleotide polymorphisms (SNP) in the CDH1 gene, -160C/A and -347G/GA in the 5'-promoter region and +54C/T in the 3'-untranslated region (UTR) have been shown to be associated with tumor development and progression via modifying transcriptional activity, mRNA stability or protein expression. To investigate the influence of CDH1 SNP on susceptibility to esophageal squamous cell carcinomas (ESCC) and gastric cardia adenocarcinomas (GCA), a case-control study was conducted among 333 ESCC patients, 239 GCA patients and 343 controls from a northern Chinese population. CDH1 polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism analysis. The results showed that; (i) genotypes with the +54C allele (C/C or C/T) significantly increased the risk of developing both ESCC and GCA compared to the +54T/T genotype (age and gender adjusted odds ratio [OR] = 1.45 and 2.28, 95% confidence interval [CI] = 1.06-1.99 and 1.58-3.30, respectively), and this association was significant only among non-smokers (OR = 1.68 and 2.64, 95% CI = 1.01-2.80 and 1.43-4.87 for ESCC and GCA, respectively), and individuals without a family history of upper gastrointestinal cancer (OR = 2.63 and 2.97, 95% CI = 1.36-5.10 and 95% CI = 1.32-6.68 for ESCC and GCA, respectively); (ii) compared with the -347G/G genotype, the -347GA and GA/GA genotypes significantly increased the risk of developing GCA (OR = 1.45, 95 % CI = 1.03-2.04); (iii) there was a significant association of CDH1-160C/-347G/+54C and -160C/-347GA/+54C haplotypes with the development of GCA, compared with the -160C/-347G/+54T haplotype (OR = 1.80 and 2.21, 95% CI = 1.33-2.44 and 1.43-3.42, respectively); and (iv) the influence of CDH1 SNP on the depth of tumor invasion and lymphatic metastasis in ESCC and GCA patients was not observed in this study. The present study indicates that CDH1 polymorphisms might modify susceptibility to ESCC and/or GCA.

Epithelial-mesenchymal transition events during human embryonic stem cell differentiation

Epithelial-mesenchymal transition (EMT) occurs during embryonic development and may also be associated with the metastatic spread of epithelial tumors. During EMT, E-cadherin is down-regulated and this correlates with increased motility and invasion of cells. We show that differentiation of human embryonic stem (ES) cells in monolayer culture is associated with an E- to N-cadherin switch, increased vimentin expression, up-regulation of E-cadherin repressor molecules (Snail and Slug proteins), and increased gelatinase (matrix metalloproteinases; MMP-2 and MMP-9) activity and cellular motility, all characteristic EMT events. The 5T4 oncofetal antigen, previously shown to be associated with early human ES cell differentiation, is also part of this process. Abrogation of E-cadherin-mediated cell-cell contact in undifferentiated ES cells using neutralizing antibody (nAb) SHE78.7 resulted in increased cellular motility, altered actin cytoskeleton arrangement and a mesenchymal phenotype together with presentation of the 5T4 antigen at the cell surface. nAb-treated ES cells remained in an undifferentiated state, as assessed by OCT-4 protein expression, and did not express EMT-associated transcripts. Removal of nAb from ES cells resulted in the restoration of cell-cell contact, absence of cell surface 5T4, decreased mesenchymal cellular morphology and motility, and enabled the differentiation of the cells to the three germ layers upon their removal from the fibroblast feeder layer. We conclude that E-cadherin functions in human ES cells to stabilize the cortical actin cyoskeletal arrangement and this prevents cell surface localization of the 5T4 antigen. Furthermore, human ES cells represent a useful model system with which to study EMT events relevant to embryonic development and tumor cell metastasis.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

E-cadherin inhibits cell surface localization of the pro-migratory 5T4 oncofetal antigen in mouse embryonic stem cells

Epithelial-mesenchymal transition (EMT) events occur during embryonic development and are important for the metastatic spread of epithelial tumors. We show here that spontaneous differentiation of mouse embryonic stem (ES) cells is associated with an E- to N-cadherin switch, up-regulation of E-cadherin repressor molecules (Snail and Slug proteins), gelatinase activity (matrix metalloproteinase [MMP]-2 and -9), and increased cellular motility, all characteristic EMT events. The 5T4 oncofetal antigen, previously shown to be associated with very early ES cell differentiation and altered motility, is also a part of this coordinated process. E- and N-cadherin and 5T4 proteins are independently regulated during ES cell differentiation and are not required for induction of EMT-associated transcripts and proteins, as judged from the study of the respective knockout ES cells. Further, abrogation of E-cadherin-mediated cell-cell contact in undifferentiated ES cells using neutralizing antibody results in a reversible mesenchymal phenotype and actin cytoskeleton rearrangement that is concomitant with translocation of the 5T4 antigen from the cytoplasm to the cell surface in an energy-dependent manner. E-cadherin null ES cells are constitutively cell surface 5T4 positive, and although forced expression of E-cadherin cDNA in these cells is sufficient to restore cell-cell contact, cell surface expression of 5T4 antigen is unchanged. 5T4 and N-cadherin knockout ES cells exhibit significantly decreased motility during EMT, demonstrating a functional role for these proteins in this process. We conclude that E-cadherin protein stabilizes cortical actin cytoskeletal arrangement in ES cells, and this can prevent cell surface localization of the promigratory 5T4 antigen.

Methylation in esophageal carcinogenesis

Genetic abnormalities of proto-oncogenes and tumor suppressor genes have been demonstrated to be changes that are frequently involved in esophageal cancer pathogenesis. However, hypermethylation of CpG islands, an epigenetic event, is coming more and more into focus in carcinogenesis of the esophagus. Recent studies have proved that promoter hypermethylation of tumor suppressor genes is frequently observed in esophageal carcinomas and seems to play an important role in the pathogenesis of this tumor type. In this review, we will discuss current research on genes that are hypermethylated in human esophageal cancer and precancerous lesions of the esophagus. We will also discuss the potential use of hypermethylated genes as targets for detection, prognosis and treatment of esophageal cancer.

Molecular screening of gastric cancer by proteome analysis

Gastric cancer affects annually more than 800,000 individuals worldwide and remains a challenge for clinicians and oncologists. Most patients with gastric cancer are diagnosed in advanced stages, when a curative resection is impossible, which leads to an overall poor prognosis. Finding new diagnostic and treatment procedures is of paramount importance to improve patient prognosis, which will be improved most dramatically by techniques that allow the detection of gastric cancer in its early stages. So far the value of conventional tumour markers such as Ca72-4 or carcinoembryonic antigen is limited, and even markers developed from molecular biological studies on the carcinogenesis of gastric cancer, such as E-cadherin and others, have not proved to be of adequate sensitivity and specificity to allow the early detection of gastric cancer. With the development of innovative diagnostic tools, such as proteome analysis, new biomarkers may be identified that may allow early diagnosis and thus screening for gastric cancer, particularly in at-risk patient populations. Recent studies have indicated that these biomarkers may be derived from the tumour itself or reflect a specific metabolic or immunological response to cancer that can be used to find gastric cancer patients at an early and putatively curative stage of the disease.

CpG island hypermethylation in progression of esophageal and gastric cancer

The upper gastrointestinal (GI) cancers have various carcinogenic pathways and precursor lesions, such as dysplasia for esophageal squamous cell carcinoma, Barrett esophagus for esophageal adenocarcinoma, and intestinal metaplasia for the intestinal-type of gastric cancer. Recently, many epigenetic events in carcinogenic pathways have been revealed, along with genomic and genetic alterations. This information has provided deeper insight into an understanding of the mechanisms of upper GI carcinogenesis. Moreover, detection methods of aberrant methylation have been applied to clinical fields to stratify high-risk groups, detect early cancer, and to predict clinical outcomes. In this review, a variety of information is summarized regarding gene hypermethylation in esophageal and gastric cancer.

Regulatory mechanisms controlling human E-cadherin gene expression

In cancer cells, loss of E-cadherin gene expression caused dysfunction of the cell-cell junction system, triggering cancer invasion and metastasis. Therefore, E-cadherin is an important tumor-suppressor gene. To understand how E-cadherin gene expression is regulated in cancer cells, we have used E-cadherin-positive and -negative expressing cells to find out the possible up- or down regulating transcription factors in human E-cadherin regulatory sequences. Functional analysis of human E-cadherin regulatory sequences constructs indicated that AML1, Sp1, and p300 may play important roles in promoting E-cadherin expression. In addition, we found there are four HNF3-binding sites in human E-cadherin regulatory sequences. The exogenous HNF3 can enhance the E-cadherin promoter activity in metastatic breast cancer cells and the metastatic breast cancer cells stably transfected with HNF3 showed re-expression of E-cadherin. The HNF3 stable transfectants changed from mesenchymal-like into epithelial morphology. The transwell assays showed the re-expressed E-cadherin reduced cell motility of metastatic breast cancer cells. These results suggested HNF3 may play important roles in the upregulation of the E-cadherin promoter, with the consequent re-expression of E-cadherin, thus reducing the metastatic potential of breast cancer cells. These findings suggested HNF3 plays important roles in the upregulation of the E-cadherin gene and may be able to reduce the motility of metastatic breast cancer cells.

DNA methylation of genes linked to retinoid signaling in squamous cell carcinoma of the esophagus: DNA methylation of CRBP1 and TIG1 is associated with tumor stage

Hypermethylation of CpG islands is associated with the silencing of various tumor suppressor genes. Retinoic acid receptor-beta (RAR-beta), cellular retinol-binding protein 1 (CRBP1), and tazarotene-induced gene 1 (TIG1) have been linked to retinoic acid signaling. Little is known about the involvement of these three genes in esophageal squamous cell carcinoma (ESCC). In this study, we investigated the methylation status of these genes and analyzed the role of methylation of their DNA in ESCC. Methylation-specific polymerase chain reaction (PCR) was performed to study the methylation of CpG islands in 28 ESCC (stages I, II, and III) and 10 samples of corresponding non-neoplastic mucosa. The mRNA expression levels of the three genes were measured by quantitative reverse transcription-PCR. DNA hypermethylation of RAR-beta was found in seven (25.0%) of the 28 ESCC, of CRBP1 in five (17.9%), and of TIG1 in five (17.9%). DNA methylation of RAR-beta was identified in one of 10 samples of corresponding non-neoplastic mucosa (10.0%), whereas no DNA methylation of CRBP1 or TIG1 was detected. In total, at least one of the three genes was hypermethylated in 12 (42.9%) ESCC. Reduced expression of RAR-beta, CRBP1, and TIG1 was found in 14 (50.0%), 15 (53.6%), and 13 (46.4%) ESCC, respectively. DNA methylation of each gene was significantly associated with reduced expression of the respective mRNA. No correlation was found between the DNA methylation status of RAR-beta and clinicopathological factors such as depth of invasion, lymph node metastasis, or tumor stage. In contrast, DNA methylation of both CRBP1 and TIG1 was observed only in stage III ESCC. These results show that inactivation of the retinoic acid signaling-associated genes RAR-beta, CRBP1, and TIG1 by DNA methylation occurs frequently in ESCC.

Novel molecular targeted therapy for esophageal cancer

Esophageal cancers are highly lethal neoplasms which are generally refractory to conventional multidisciplinary interventions. Recent elucidation of the mechanisms of esophageal carcinogenesis, as well as preclinical studies utilizing chromatin remodeling agents and inhibitors of oncogene signaling in conjunction with conventional chemotherapeutic agents provide new opportunities for the development of potentially efficacious molecular targeted therapies for these malignancies.

Infiltrating leukocytes confound the detection of E-cadherin promoter methylation in tumors

Promoter hypermethylation is known to result in transcriptional downregulation of many genes including the CDH1 gene. In this study we set out to determine CDH1 promoter methylation in breast tumors with decreased or absent E-cadherin protein expression and without CDH1 gene mutations by methylation-specific PCR (MSP). Interestingly, some tumor samples with normal E-cadherin expression yielded a methylation-specific PCR product. We hypothesized that other cells than tumor cells contribute to these products. Since in normal breast tissue no CDH1 promoter methylation is detected, infiltrating leukocytes, often present in tumors, might account for these methylation-specific fragments. Indeed, a methylation-specific fragment is found in all twelve leukocyte samples tested. Furthermore, activated T-cells also yielded a methylation-specific fragment. Sequencing of these fragments reveals two distinct methylation profiles. Leukocytes have only partial methylation of some CpGs, while the tumor-associated methylation profile shows complete methylation of most CpGs. Therefore, to assess whether CDH1 methylation is tumor associated, sequencing of MSP products is a prerequisite. Here we show that out of six lobular tumors lacking E-cadherin protein expression, three have tumor-associated CDH1 promoter methylation while in three other tumors no methylation is detected.

Molecular aspects of esophageal squamous cell carcinoma carcinogenesis

BACKGROUND

The development of human esophageal cancer is a multistep, progressive process. An early indicator of this process is an increased proliferation of esophageal epithelial cells morphologically including basal cell hyperplasia, dysplasia, carcinoma in situ and advanced esophageal squamous cell carcinoma. The process of tumorigenesis at cellular level is related to disorders of the control of cell proliferation and differentiation and controlled cell death (apoptosis). Most of cancer cells contain genetic alterations related to the control of these processes, including transcription factors and apoptosis related proteins.

AIM

In this review, the current knowledge of the genetic profile of this subtype of esophageal tumor is discussed, focusing on the potential of the development of novel tools for clinical management of esophageal squamous cell carcinoma.

CONCLUSIONS

The advances in the field of molecular biology have let us to deeper our knowledge of the process of carcinogenesis of esophagus. Ideally, this knowledge should be translated in benefits for patients suffering from cancer. Thus, better understanding of molecular alterations during carcinogenesis is expected to improve tumor control and prevention and also may lead to better disease management.

Downregulation of retinoic acid receptor-β2 expression is linked to aberrant methylation in esophageal squamous cell carcinoma cell lines

AIM: To study the role of hypermethylation in the loss of retinoic acid receptor β₂ (RARβ₂) in esophageal squamous cell carcinoma (ESCC).

METHODS: The role of hypermethylation in RARβ₂ gene silencing in 6 ESCC cell lines was determined by methylation-specific PCR (MSP), and its methylation status was compared with RARβ₂ mRNA expression by RT-PCR. The MSP results were confirmed by bisulfite sequencing of RARβ₂ promoter regions.

RESULTS: Methylation was detected in 4 of the 6 cell lines, and the expression of RARβ₂ was markedly downregulated in 3 of the 4 methylated cell lines. The expression of RARβ₂ was restored in one RARβ₂ -downregulated cell line with the partial demethylation of promoter region of RARβ₂ after 5-aza-2’-deoxycytidine (5-aza-dc) treatment.

CONCLUSION: The methylation of the 5’ region may play an important role in the downregulation of RARβ₂ in some ESCC cell lines, suggesting that multiple mechanisms contribute to the loss of RARβ₂ expression in ESCC cell lines. This study may have clinical applications for treatment and prevention of ESCC.

Cadherins in cancer

The presence of a functional E-cadherin/catenin cell-cell adhesion complex is a prerequisite for normal development and maintenance of epithelial structures in the mammalian body. This implies that the acquisition of molecular abnormalities that disturb the expression or function of this complex is related to the development and progression of most, if not all, epithelial cell-derived tumors, i.e. carcinomas. E-cadherin downregulation is indeed correlated with malignancy parameters such as tumor progression, loss of differentiation, invasion and metastasis, and hence poor prognosis. Moreover, E-cadherin has been shown to be a potent invasion suppressor as well as a tumor suppressor. Disturbed expression profiles of the E-cadherin/catenin complex have been demonstrated in histological sections of many human tumor types. In different kinds of carcinomas, biallelic downregulation of the E-cadherin gene, resulting in tumor-restricted decrease or even complete loss of E-cadherin expression, appears to be caused by a variety of inactivation mechanisms. Gene deletion due to loss of heterozygosity of the CDH1 locus on 16q22.1 frequently occurs in many carcinoma types. However, somatic inactivating mutations resulting in aberrant E-cadherin expression by loss of both wild-type alleles is rare and restricted to only a few cancer types. A majority of carcinomas thus seems to show deregulated E-cadherin expression by other mechanisms. The present evidence proposes transcriptional repression as a powerful and recurrent molecular mechanism for silencing E-cadherin expression. The predominant mechanisms emerging in most carcinomas are hypermethylation of the E-cadherin promoter and expression of transrepressor molecules such as SIP1, Snail, and Slug that bind sequence elements in the proximal E-cadherin promoter. Interestingly, complex differential expression of other cadherins seems to be associated with loss of E-cadherin and to reinforce effects of this loss on tumor progression. Multiple agents can upregulate and stabilize the E-cadherin/catenin complex. Especially for those tumors with transcriptional and thus reversible downregulation of E-cadherin expression, these drug agents offer important therapeutic opportunities.

Upregulated expression of Ezrin and invasive phenotype in malignantly transformed esophageal epithelial cells

AIM: To investigate the correlation between ezrin expression and invasive phenotype formation in malignantly transformed esophageal epithelial cells.

METHODS: The experimental cell line employed in the present study was originated form the progressive induction of a human embryonic esophageal epithelial cell line (SHEE) by the E6E7 genes of human papillomavirus (HPV) type 18. The cells at the 35^th passage after induction called SHEEIMM were in a state of immortalized phase and used as the control, while that of the 85^th passage denominated as SHEEMT represented the status of cells that were malignantly transformed. The expression changes of ezrin and its mRNA in both cell passages were respectively analyzed by RT-PCR and Western blot. Invasive phenotype was assessed in vivo by inoculating these cells into the severe combined immunodeficient (SCID) mice via subcutaneous and intraperitoneal injection, and in vitro by inoculating them on the surface of the amnion membranes, which then was determined by light microscopy and scanning electron microscopy.

RESULTS: Upregulated expression of ezrin protein and its mRNA was observed in SHEEMT compared with that in SHEEIMM cells. The SHEEMT cells inoculated in SCID mice were observed forming tumor masses in both visceral organs and soft tissues in a period of 40 d with a special propensity to invading mesentery and pancreas, but did not exhibit hepatic metastases. Pathologically, these tumor cells harboring larger nucleus, nucleolus and less cytoplasm could infiltrate and destroy adjacent tissues. In the in vitro study, the inoculated SHEEMT cells could grow in cluster on the amniotic epithelial surface and intrude into the amniotic stroma. In contrast, unrestricted growth and invasiveness were not found in SHEEIMM cells in both in vivo and in vitro experiment.

CONCLUSION: The upregulated ezrin expression is one of the important factors that are possibly associated with the invasive phenotype formation in malignantly transformed esophageal epithelial cells.

Expression of ECRG4, a novel esophageal cancer-related gene, downregulated by CpG island hypermethylation in human esophageal squamous cell carcinoma

AIM: To study the mechanisms responsible for inactivation of a novel esophageal cancer related gene 4 (ECRG4) in esophageal squamous cell carcinoma (ESCC).

METHODS: A pair of primers was designed to amplify a 220 bp fragment, which contains 16 CpG sites in the core promoter region of the ECRG 4 gene. PCR products of bisulfite-modified CpG islands were analyzed by denaturing high-performance liquid chromatography (DHPLC), which were confirmed by DNA sequencing. The methylation status of ECRG 4 promoter in 20 cases of esophageal cancer and the adjacent normal tissues, 5 human tumor cell lines (esophageal cancer cell line-NEC, EC109, EC9706; gastric cancer cell line- GLC; human embryo kidney cell line-Hek293) and 2 normal esophagus tissues were detected. The expression level of the ECRG 4 gene in these samples was examined by RT-PCR.

RESULTS: The expression level of ECRG 4 gene was varied. Of 20 esophageal cancer tissues, nine were unexpressed, six were lowly expressed and five were highly expressed compared with the adjacent tissues and the 2 normal esophageal epithelia. In addition, 4 out of the 5 human cell lines were also unexpressed. A high frequency of methylation was revealed in 12 (8 unexpressed and 4 lowly expressed) of the 15 (80%) downregulated cancer tissues and 3 of the 4 unexpressed cell lines. No methylation peak was observed in the two highly expressed normal esophageal epithelia and the methylation frequency was low (3/20) among the 20 cases in the highly expressed adjacent tissues. The methylation status of the samples was consistent with the result of DNA sequencing.

CONCLUSION: These results indicate that the inactivation of ECRG 4 gene by hypermethylation is a frequent molecular event in ESCC and may be involved in the carcinogenesis of this cancer.

Expression of MUC1 in esophageal squamous-cell carcinoma and its relationship with prognosis of patients from Linzhou city, a high incidence area of northern China

AIM: To further characterize the possible relationship between the molecular changes and prognosis of ESC and to elucidate the possible mechanisms involved.

METHODS: 114 specimens of ESC were collected from Linzhou city, and all patients were followed up for more than 5 years after resection. Histopathological analysis and immunohistochemical staining (ABC) were employed to detect the alteration of MUC1.

RESULTS: The positive immunostaining rate for MUC1 was 79% (90/114), and the high-expression rate was 63% (72/114). The mean survival periods (months) of those with high- and low-expression rates of MUC1 were 41 (95%CI: 35, 47) and 52 (95%CI: 45, 59), respectively. Patients in the low-expression group obviously survived longer than those in high-expression group, and the difference was significant (P < 0.05). The expression of MUC1 protein in the esophageal carcinoma specimens with metastasis was stronger than those without metastasis, the difference was also significant (P < 0.05). The stepwise multivariate analysis showed that “differentiation”, “expression of MUC1” and “TNM staging” were the most important factors affecting the prognosis of esophageal carcinoma patients (P < 0.05).

CONCLUSION: A good correlation between the alteration of MUC1 and the regional lymph node metastasis was observed. Furthermore, high-expression of MUC1 was associated with poor prognosis for esophageal cancer patients. These results indicated that MUC1 is a promising biomarker for predicting lymph node metastasis and prognosis in esophageal cancer.

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.

Epigenetic versus genetic alterations in the inactivation of E-cadherin

Genetic mutation of genes that inhibit the formation of tumours has long been known to be one of the main driving forces in the development of cancer. Inactivation of one such gene, E-cadherin, is thought to be an important step in the development of most, or all, epithelial derived tumour types. Mutations within the E-cadherin gene have been identified as the cause of familial gastric cancer and loss of expression of E-cadherin has been found to be widespread in sporadically occurring epithelial tumours. Despite this, mutations of the E-cadherin gene have been only rarely found in most types of sporadic cancers. However, recent evidence has identified a second mechanism potentially responsible for inactivation of E-cadherin, and other important genes, during tumourigenesis, namely DNA methylation. This review will examine the importance of genetic (mutation) versus epigenetic (DNA methylation) mechanisms in the inactivation of E-cadherin during tumour development and also discuss potential differences in the functional consequences between inactivation by epigenetic or genetic means.

Molecular staging of lung and esophageal cancer

In both esophageal and NSCLC, the TNM stage at diagnosis remains the most important determinant of survival. Significant research to investigate the biology of NSCLC and esophageal carcinoma is ongoing, and the roles of proto-oncogenes, tumor suppressor genes, angiogenic factors, extracellular matrix proteases, and adhesion molecules are being elucidated. While evidence is accumulating that various markers are involved in NSCLC and esophageal tumor virulence, the current studies are compromised by small sample sizes, heterogeneous populations, and variations in techniques. Large prospective studies with homogenous groups designed to evaluate the role of these various markers should clarify their potential involvement in NSCLC and esophageal cancer. Identification of occult micrometastases in lymph nodes and bone marrow using immunohistochemical techniques and rt-PCR is intriguing. These techniques are promising as a method to more accurately stage patients, and therefore to predict outcomes and to determine therapies. Perhaps the most promising area of research is the development of novel drugs whose mechanism of action targets the pathways of various molecular markers. Molecular biologic substaging offers an opportunity to individualize a chemotherapeutic regimen based on the molecular profile of the tumor, thus providing the potential for improved outcomes with less morbidity in patients with both NSCLC and esophageal cancer.