Mutations in beta-catenin and APC genes are uncommon in esophageal and esophagogastric junction adenocarcinomas

Alteration in DNA methylation patterns: Epigenetic signatures in gastrointestinal cancers

Abnormalities in epigenetic modifications can cause malignant transformations in cells, leading to cancers of the gastrointestinal (GI) tract, which accounts for 20% of all cancers worldwide. Among the epigenetic alterations, DNA hypomethylation is associated with genomic instability. In addition, CpG methylation and promoter hypermethylation have been recognized as biomarkers for different malignancies. In GI cancers, epigenetic alterations affect genes responsible for cell cycle control, DNA repair, apoptosis, and tumorigenic-specific signaling pathways. Understanding the pattern of alterations in DNA methylation in GI cancers could help scientists discover new molecular-based pharmaceutical treatments. This study highlights alterations in DNA methylation in GI cancers. Understanding epigenetic differences among GI cancers may improve targeted therapies and lead to the discovery of new diagnostic biomarkers.

Somatic mutations of esophageal adenocarcinoma: a comparison between Black and White patients

Esophageal adenocarcinoma is the most common histological subtype of esophageal cancer in Western countries and shows poor prognosis with rapid growth. EAC is characterized by a strong male predominance and racial disparity. EAC is up to fivefold more common among Whites than Blacks, yet Black patients with EAC have poorer survival rates. The racial disparity remains largely unknown, and there is limited knowledge of mutations in EAC regarding racial disparities. We used whole-exome sequencing to show somatic mutation profiles derived from tumor samples from 18 EAC male patients. We identified three molecular subgroups based on the pre-defined esophageal cancer-specific mutational signatures. Group 1 is associated with age and NTHL1 deficiency-related signatures. Group 2 occurs primarily in Black patients and is associated with signatures related to DNA damage from oxidative stress and NTHL1 deficiency-related signatures. Group 3 is associated with defective homologous recombination-based DNA often caused by BRCA mutation in White patients. We observed significantly mutated race related genes (LCE2B in Black, SDR39U1 in White) were (q-value < 0.1). Our findings underscore the possibility of distinct molecular mutation patterns in EAC among different races. Further studies are needed to validate our findings, which could contribute to precision medicine in EAC.

Reflux conditions induce E-cadherin cleavage and EMT via APE1 redox function in oesophageal adenocarcinoma

OBJECTIVE

Chronic gastro-oesophageal reflux disease, where acidic bile salts (ABS) reflux into the oesophagus, is the leading risk factor for oesophageal adenocarcinoma (EAC). We investigated the role of ABS in promoting epithelial-mesenchymal transition (EMT) in EAC.

DESIGN

RNA sequencing data and public databases were analysed for the EMT pathway enrichment and patients' relapse-free survival. Cell models, pL2-IL1β transgenic mice, deidentified EAC patients' derived xenografts (PDXs) and tissues were used to investigate EMT in EAC.

RESULTS

Analysis of public databases and RNA-sequencing data demonstrated significant enrichment and activation of EMT signalling in EAC. ABS induced multiple characteristics of the EMT process, such as downregulation of E-cadherin, upregulation of vimentin and activation of ß-catenin signalling and EMT-transcription factors. These were associated with morphological changes and enhancement of cell migration and invasion capabilities. Mechanistically, ABS induced E-cadherin cleavage via an MMP14-dependent proteolytic cascade. Apurinic/apyrimidinic endonuclease (APE1), also known as redox factor 1, is an essential multifunctional protein. APE1 silencing, or its redox-specific inhibitor (E3330), downregulated MMP14 and abrogated the ABS-induced EMT. APE1 and MMP14 coexpression levels were inversely correlated with E-cadherin expression in human EAC tissues and the squamocolumnar junctions of the L2-IL1ß transgenic mouse model of EAC. EAC patients with APE1high and EMThigh signatures had worse relapse-free survival than those with low levels. In addition, treatment of PDXs with E3330 restrained EMT characteristics and suppressed tumour invasion.

CONCLUSION

Reflux conditions promote EMT via APE1 redox-dependent E-cadherin cleavage. APE1-redox function inhibitors can have a therapeutic role in EAC.

Dynamic switch of immunity and antitumor effects of metformin in rat spontaneous esophageal carcinogenesis

Chronic inflammation contributes to tumor development by creating a local microenvironment that facilitates neoplastic transformation and potentiates the progression of cancer. Esophageal cancer (EC) is an inflammation-associated malignancy with a poor prognosis. The nature of the switch between chronic inflammation of the esophagus and EC-related immunological changes remains unclear. Here, we examined the dynamic alterations of immune cells at different stages of chronic esophagitis, Barrett’s esophagus (BE) and EC using an esophageal spontaneous carcinogenesis rat model. We also investigated the anticancer effects of metformin. To stimulate EC carcinogenesis, chronic gastroduodenal reflux esophagitis via esophagojejunostomy was induced in 120 rats in metformin-treated and non-treated (control) groups. After 40 weeks, BE and EC developed in 96.7% and 63.3% of the control group, and in 66.7% and 23.3% of the metformin-treated group, respectively. Flow cytometric analysis demonstrated that the balance of M1/M2-polarized or phospho-Stat3-positive macrophages, regulatory T, cytotoxic T, natural killer (NK), NK T cells, and Th17 T cells was dynamically changed at each stage of the disease and were resolved by metformin treatment. These findings clarify the immunity in esophageal carcinogenesis and suggest that metformin could suppress this disease by improving the immunosuppressive tumor microenvironment and immune evasion.

Family History of Colorectal or Esophageal Cancer in Barrett's Esophagus and Potentially Explanatory Genetic Variants

We aimed to estimate the effects of a family history of colorectal cancer (CRC) or esophageal cancer on the risk of Barrett's esophagus (BE) and identify variants in cancer genes that may explain the association.

In-depth characterization of the Wnt-signaling/β-catenin pathway in an in vitro model of Barrett's sequence

BACKGROUND

An altered Wnt-signaling activation has been reported during Barrett's esophagus progression, but with rarely detected mutations in APC and β-catenin (CTNNB1) genes.

METHODS

In this study, a robust in-depth expression pattern analysis of frizzled receptors, co-receptors, the Wnt-ligands Wnt3a and Wnt5a, the Wnt-signaling downstream targets Axin2, and CyclinD1, as well as the activation of the intracellular signaling kinases Akt and GSK3β was performed in an in vitro cell culture model of Barrett's esophagus. Representing the Barrett's sequence, we used normal esophageal squamous epithelium (EPC-1, EPC-2), metaplasia (CP-A) and dysplasia (CP-B) to esophageal adenocarcinoma (EAC) cell lines (OE33, OE19) and primary specimens of squamous epithelium, metaplasia and EAC.

RESULTS

A loss of Wnt3a expression was observed beginning from the metaplastic cell line CP-A towards dysplasia (CP-B) and EAC (OE33 and OE19), confirmed by a lower staining index of WNT3A in Barrett's metaplasia and EAC, than in squamous epithelium specimens. Frizzled 1-10 expression analysis revealed a distinct expression pattern, showing the highest expression for Fzd2, Fzd3, Fzd4, Fzd5, Fzd7, and the co-receptor LRP5/6 in EAC cells, while Fzd3 and Fzd7 were rarely expressed in primary specimens from squamous epithelium.

CONCLUSION

Despite the absence of an in-depth characterization of Wnt-signaling-associated receptors in Barrett's esophagus, by showing variations of the Fzd- and co-receptor profiles, we provide evidence to have a significant role during Barrett's progression and the underlying pathological mechanisms.

Modeling Wnt signaling by CRISPR-Cas9 genome editing recapitulates neoplasia in human Barrett epithelial organoids

Primary organoid cultures generated from patient biopsies comprise a novel improved platform for disease modeling, being genetically stable and closely recapitulating in vivo scenarios. Barrett esophagus (BE) is the major risk factor for esophageal adenocarcinoma. There has been a dearth of long-term in vitro expansion models of BE neoplastic transformation. We generated a long-term virus-free organoid expansion model of BE neoplasia from patient biopsies. Both wild-type and paired APC-knockout (APC^KO) BE organoids genome-edited by CRISPR-Cas9 showed characteristic goblet cell differentiation. Autonomous Wnt activation was confirmed in APC^KO organoids by overexpression of Wnt target genes and nuclear-translocated β-catenin expression after withdrawal of Wnt-3A and R-spondin-1. Wnt-activated organoids demonstrated histologic atypia, higher proliferative and replicative activity, reduced apoptosis, and prolonged culturability. Wnt-activated organoids also showed sustained protrusive migration ability accompanied by disrupted basement membrane reorganization and integrity. This CRISPR-Cas9 editing human-derived organoid model recapitulates the critical role of aberrant Wnt/β-catenin signaling activation in BE neoplastic transformation. This system can be used to study other 'driver' pathway alterations in BE-associated neoplasia, avoiding signaling noise present in immortalized or cancer-derived cell lines.

Modeling Wnt signaling by CRISPR-Cas9 genome editing recapitulates neoplasia in human Barrett epithelial organoids

Primary organoid cultures generated from patient biopsies comprise a novel improved platform for disease modeling, being genetically stable and closely recapitulating in vivo scenarios. Barrett esophagus (BE) is the major risk factor for esophageal adenocarcinoma. There has been a dearth of long-term in vitro expansion models of BE neoplastic transformation. We generated a long-term virus-free organoid expansion model of BE neoplasia from patient biopsies. Both wild-type and paired APC-knockout (APC^KO) BE organoids genome-edited by CRISPR-Cas9 showed characteristic goblet cell differentiation. Autonomous Wnt activation was confirmed in APC^KO organoids by overexpression of Wnt target genes and nuclear-translocated β-catenin expression after withdrawal of Wnt-3A and R-spondin-1. Wnt-activated organoids demonstrated histologic atypia, higher proliferative and replicative activity, reduced apoptosis, and prolonged culturability. Wnt-activated organoids also showed sustained protrusive migration ability accompanied by disrupted basement membrane reorganization and integrity. This CRISPR-Cas9 editing human-derived organoid model recapitulates the critical role of aberrant Wnt/β-catenin signaling activation in BE neoplastic transformation. This system can be used to study other 'driver' pathway alterations in BE-associated neoplasia, avoiding signaling noise present in immortalized or cancer-derived cell lines.

Decreased expression of CDH1 or CTNNB1 affects poor prognosis of patients with esophageal cancer

Background

E-cadherin/CDH1 is one of the proteins involved in cell adhesion, and it is known that decreased expression of E-cadherin induces lymph node metastasis in esophageal cancer. Beta catenin/CTNNB1, which is an important component of the Wnt signaling pathway, binds to E-cadherin at the cell membrane, where the complex of these two proteins functions in the stabilization of cell adhesion. However, its role in the pathogenesis of esophageal cancer is still unknown.

Methods

This study included 86 patients with esophageal cancer who underwent surgery between 1998 and 2007. The expression of the E-cadherin/CDH1 gene product (E-cadherin/CDH1) and that of the beta catenin/CTNNB1 protein in the cell membrane were analyzed by immunohistochemistry. We examined the correlations among CDH1 or CTNNB1 expression, clinicopathological factors, and the prognosis of patients with ESCC.

Results

CDH1 and CTNNB1 were expressed in 52.3 % (45/86) and 36.0 % (31/86) of tumor samples, respectively. Both CDH1 and CTNNB1 were co-expressed in 22.1 % (19/86) of esophageal cancer tissues. CDH1 expression correlated with the p-stage (stages I–II vs stages III–IV, p = 0.032), T factor (T1–2 vs T3–4, p = 0.0088), and lymphatic invasion (p = 0.019). However, CDH1 expression did not correlate with the N factor or the blood vessel invasion. CTNNB1 expression correlated with the T factor (T1–2 vs T3–4, p = 0.0015), p-stage (stages I–II vs stages III–IV, p = 0.030), and lymphatic invasion (p = 0.007). The CDH1(+)/CTNNB1(+) phenotype was inversely correlated with the T factor, N factor, p-stage, lymphatic invasion, and blood vessel invasion. Furthermore, patients whose tumors were double-positive for CDH1 and CTNNB1 had a significantly higher survival rate than those whose tumors were negative for CDH1 or CTNNB1 (log-rank test, p = 0.0192). The T factor and N factor had a strong negative correlation with double-positive tumors. These were both independent prognostic factors, as was the double-positive phenotype. A univariate analysis indicated that the T factor, the N factor, and CDH1 and CTNNB1 co-expression were significant variables that predicted survival (hazard ratio, 2.387; 95 % confidence interval, 1.115–5.102; p = 0.025).

Conclusions

Decreased expression of CDH1 or CTNNB1 in the cell membranes of cancer cells is associated with poor survival of patients with esophageal cancer.

Wnt/β-Catenin Signaling Activation beyond Robust Nuclear β-Catenin Accumulation in Nondysplastic Barrett's Esophagus: Regulation via Dickkopf-1

INTRODUCTION: Wnt/β-catenin signaling activation has been reported only during the late steps of Barrett’s esophagus (BE) neoplastic progression, but not in BE metaplasia, based on the absence of nuclear β-catenin. However, β-catenin transcriptional activity has been recorded in absence of robust nuclear accumulation. Thus, we aimed to investigate the Wnt/β-catenin signaling in nondysplastic BE. METHODS: Esophageal tissues from healthy and BE patients without dysplasia were analyzed for Wnt target gene expression by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and immunohistochemistry. Esophageal squamous (EPC1-& EPC2-hTERT), BE metaplastic (CP-A), and adenocarcinoma (OE33) cell lines were characterized for Wnt activation by qRT-PCR, Western blot, and luciferase assay. Wnt activity regulation was examined by using recombinant Wnt3a and Dickkopf-1 (Dkk1) as well as Dkk1 short interfering RNA. RESULTS: Wnt target genes (AXIN2, c-MYC, Cyclin D1, Dkk1) and Wnt3a were significantly upregulated in nondysplastic BE compared with squamous mucosa. Elevated levels of dephosphorylated β-catenin were detected in nondysplastic BE. Nuclear active β-catenin and TOPflash activity were increased in CP-A and OE33 cells compared with squamous cells. Wnt3a-mediated β-catenin signaling activation was abolished by Dkk1 in CP-A cells. TOPFlash activity was elevated following Dkk1 silencing in CP-A but not in OE33 cells. Dysplastic and esophageal adenocarcinoma tissues demonstrated further Dkk1 and AXIN2 overexpression. CONCLUSIONS: Despite the absence of robust nuclear accumulation, β-catenin is transcriptionally active in nondysplastic BE. Dkk1 overexpression regulates β-catenin signaling in BE metaplastic but not in adenocarcinoma cells, suggesting that early perturbation of Dkk1-mediated signaling suppression may contribute to BE malignant transformation.

Dysregulation of WNT5A/ROR2 Signaling Characterizes the Progression of Barrett-Associated Esophageal Adenocarcinoma

The mechanism underlying the progression of normal esophageal mucosa to esophageal adenocarcinoma remains elusive. WNT5A is a noncanonical WNT, which mainly functions via the receptor tyrosine kinase-like orphan receptor 2 (ROR2), and has an unclear role in carcinogenesis. In this study, we aimed to determine the role of WNT5A/ROR2 signaling in esophageal adenocarcinoma. Analysis of WNT5A and ROR2 expression patterns in healthy controls, Barrett and esophageal adenocarcinoma patients' esophageal clinical specimens as well as in various esophageal cell lines demonstrated a ROR2 overexpression in esophageal adenocarcinoma tissues compared with Barrett and healthy mucosa, whereas WNT5A expression was found significantly downregulated toward esophageal adenocarcinoma formation. Treatment of esophageal adenocarcinoma OE33 cells with human recombinant WNT5A (rhWNT5A) significantly suppressed proliferation, survival, and migration in a dose-dependent fashion. rhWNT5A was found to inhibit TOPflash activity in ROR2 wild-type cells, whereas increased TOPflash activity in ROR2-knockdown OE33 cells. In addition, ROR2 knockdown alone abolished cell proliferation and weakened the migration properties of OE33 cells. These findings support an early dysregulation of the noncanonical WNT5A/ROR2 pathway in the pathogenesis of esophageal adenocarcinoma, with the loss of WNT5A expression together with the ROR2 overexpression to be consistent with tumor promotion.

IMPLICATIONS

The dysregulation of WNT5A/ROR2 noncanonical WNT signaling in Barrett-associated esophageal adenocarcinoma introduces possible prognostic markers and novel targets for tailored therapy of this malignancy. Mol Cancer Res; 14(7); 647-59. ©2016 AACR.

SOX10, a novel HMG-box-containing tumor suppressor, inhibits growth and metastasis of digestive cancers by suppressing the Wnt/β-catenin pathway

SOX10 was identified as a methylated gene in our previous cancer methylome study. Here we further analyzed its epigenetic inactivation, biological functions and related cell signaling in digestive cancers (colorectal, gastric and esophageal cancers) in detail. SOX10 expression was decreased in multiple digestive cancer cell lines as well as primary tumors due to its promoter methylation. Pharmacologic or genetic demethylation reversed SOX10 silencing. Ectopic expression of SOX10in SOX10-deficient cancer cells inhibits their proliferation, tumorigenicity, and metastatic potentials in vitro and in vivo. SOX10 also suppressed the epithelial to mesenchymal transition (EMT) and stemness properties of digestive tumor cells. Mechanistically, SOX10 competes with TCF4 to bind β-catenin and transrepresses its downstream target genes via its own DNA-binding property. SOX10 mutations that disrupt the SOX10-β-catenin interaction partially prevented tumor suppression. SOX10is thus a commonly inactivated tumor suppressor that antagonizes Wnt/β-catenin signaling in cancer cells from different digestive tissues.

Embryological signaling pathways in Barrett's metaplasia development and malignant transformation; mechanisms and therapeutic opportunities

Barrett's metaplasia of the esophagus (BE) is the precursor lesion of esophageal adenocarcinoma (EAC), a deadly disease with a 5-year overall survival of less than 20%. The molecular mechanisms of BE development and its transformation to EAC are poorly understood and current surveillance and treatment strategies are of limited efficacy. Increasing evidence suggests that aberrant signaling through pathways active in the embryological development of the esophagus contributes to BE development and progression to EAC. We discuss the role that the Bone morphogenetic protein, Hedgehog, Wingless-Type MMTV Integration Site Family (WNT) and Retinoic acid signaling pathways play during embryological development of the esophagus and their contribution to BE development and malignant transformation. Modulation of these pathways provides new therapeutic opportunities. By integrating findings in developmental biology with those from translational research and clinical trials, this review provides a platform for future studies aimed at improving current management of BE and EAC.

High resolution integrative analysis reveals widespread genetic and epigenetic changes after chronic in-vitro acid and bile exposure in Barrett's epithelium cells

Barrett's epithelium (BE) is a premalignant condition resulting from chronic gastroesophageal reflux that may progress to esophageal adenocarcinoma (EAC). Early intervention holds promise in preventing BE progression. However, identification of high-risk BE patients remains challenging due to inadequate biomarkers for early diagnosis. We investigated the effect of prolonged chronic acid and bile exposure on transcriptome, methylome, and mutatome of cells in an in-vitro BE carcinogenesis (BEC) model. Twenty weeks acid and bile exposed cells from the BEC model (BEC20w) were compared with their naïve predecessors HiSeq Illumina based RNA sequencing was performed on RNA from both the cells for gene expression and mutational analysis. HELP Tagging Assay was performed for DNA methylation analysis. Ingenuity pathway, Gene Ontology, and KEGG PATHWAY analyses were then performed on datasets. Widespread aberrant genetic and epigenetic changes were observed in the BEC20w cells. Combinatorial analyses revealed 433 from a total of 863 downregulated genes had accompanying hypermethylation of promoters. Simultaneously, 690 genes from a total of 1,492 were upregulated with accompanying promoter hypomethylation. In addition, 763 mutations were identified on 637 genes. Ingenuity pathway analysis, Gene Ontology, and KEGG PATHWAY analyses associated the genetic and epigenetic changes in BEC20w cells with cellular and biological functions. Integration of high resolution comparative analyses of naïve BAR-T and BEC20w cells revealed striking genetic and epigenetic changes induced by chronic acid and bile exposure that may disrupt normal cellular functions and promote carcinogenesis. This novel study reveals several potential targets for future biomarkers and therapeutic development.

Signaling pathways in the molecular pathogenesis of adenocarcinomas of the esophagus and gastroesophageal junction

Esophageal adenocarcinoma develops in response to severe gastroesophageal reflux disease through the precursor lesion Barrett esophagus, in which the normal squamous epithelium is replaced by a columnar lining. The incidence of esophageal adenocarcinoma in the United States has increased by over 600% in the past 40 years and the overall survival rate remains less than 20% in the community. This review highlights some of the signaling pathways for which there is some evidence of a role in the development of esophageal adenocarcinoma. An increasingly detailed understanding of the biology of this cancer has emerged recently, revealing that in addition to the well-recognized alterations in single genes such as p53, p16, APC, and telomerase, there are interactions between the components of the reflux fluid, the homeobox gene Cdx2, and the Wnt, Notch, and Hedgehog signaling pathways.

Exome and whole-genome sequencing of esophageal adenocarcinoma identifies recurrent driver events and mutational complexity

The incidence of esophageal adenocarcinoma (EAC) has risen 600% over the last 30 years. With a 5-year survival rate of ~15%, the identification of new therapeutic targets for EAC is greatly important. We analyze the mutation spectra from whole-exome sequencing of 149 EAC tumor-normal pairs, 15 of which have also been subjected to whole-genome sequencing. We identify a mutational signature defined by a high prevalence of A>C transversions at AA dinucleotides. Statistical analysis of exome data identified 26 significantly mutated genes. Of these genes, five (TP53, CDKN2A, SMAD4, ARID1A and PIK3CA) have previously been implicated in EAC. The new significantly mutated genes include chromatin-modifying factors and candidate contributors SPG20, TLR4, ELMO1 and DOCK2. Functional analyses of EAC-derived mutations in ELMO1 identifies increased cellular invasion. Therefore, we suggest the potential activation of the RAC1 pathway as a contributor to EAC tumorigenesis.

Activation of Wnt signalling promotes development of dysplasia in Barrett's oesophagus

Barrett's oesophagus is a precursor of oesophageal adenocarcinoma, via intestinal metaplasia and dysplasia. Risk of cancer increases substantially with dysplasia, particularly high-grade dysplasia. Thus, there is a clinical need to identify and treat patients with early-stage disease (metaplasia and low-grade dysplasia) that are at high risk of cancer. Activated Wnt signalling is critical for normal intestinal development and homeostasis, but less so for oesophageal development. Therefore, we asked whether abnormally increased Wnt signalling contributes to the development of Barrett's oesophagus (intestinal metaplasia) and/or dysplasia. Forty patients with Barrett's metaplasia, dysplasia or adenocarcinoma underwent endoscopy and biopsy. Mice with tamoxifen- and β-naphthoflavone-induced expression of activated β-catenin were used to up-regulate Wnt signalling in mouse oesophagus. Immunohistochemistry of β-catenin, Ki67, a panel of Wnt target genes, and markers of intestinal metaplasia was performed on human and mouse tissues. In human tissues, expression of nuclear activated β-catenin was found in dysplasia, particularly high grade. Barrett's metaplasia did not show high levels of activated β-catenin. Up-regulation of Ki67 and Wnt target genes was also mostly associated with high-grade dysplasia. Aberrant activation of Wnt signalling in mouse oesophagus caused marked tissue disorganization with features of dysplasia, but only selected molecular indicators of metaplasia. Based on these results in human tissues and a mouse model, we conclude that abnormal activation of Wnt signalling likely plays only a minor role in initiation of Barrett's metaplasia but a more critical role in progression to dysplasia.

Qualitative analysis of Adenomatous Polyposis Coli promoter: hypermethylation, engagement and effects on survival of patients with esophageal cancer in a high risk region of the world, a potential molecular marker

Background

Squamous cell carcinoma of esophagus (SCCE) occurs at a high incidence rate in certain parts of the world. This feature necessitates that different aspects of the disease and in particular genetic characteristics be investigated in such regions. In addition, such investigations might lead to achievement of molecular markers helpful for early detection, successful treatment and follow up of the disease. Adenomatous Polyposis Coli (APC) promoter hypermethylation has been shown to be a suitable marker for both serum and solid tumors of adenocarcinoma of esophagus. We investigated the status of APC promoter hypermethylation in Iranian patients, compared the results with the former studies, and evaluated its applicability as a candidate molecular marker by examining association between survival of SCCE patients and APC promoter methylation.

Methods

For evaluating the status of APC promoter hypermethylation and its association with SCCE, a qualitative methylation specific PCR (MSP) was used. DNA was extracted and digested with an appropriate restriction enzyme, treated with sodium bisulfite in agarose beads and amplified in two-step PCR reaction by applying either methylated or unmethylated promoter specific primers. Universally methylated DNA and methylase treated blood DNA of healthy donors were used as positive controls as well. Survival of patients was followed up for two years after treatment and survival rate of patients with methylated APC promoter was compared with that of unmethylated patients.

Results

Assessment of APC promoter methylation revealed that normal tissues were unmethylated, while twenty out of forty five (44.4%) tumor tissues were hypermethylated either in one or both alleles of APC. Among the tissues in which methylation was detected, seven were hypermethylated in both alleles while the other thirteen were hypermethylated in one of the two alleles of APC. Analyzing two-year survival rate of patients with respect to promoter hypermethylation showed a lower rate of survival for patients with methylated APC promoter following their treatment. Further investigation into the association between promoter hypermethylation and tumor differentiation status indicated that patients with well differentiated tumors were more likely to develop promoter hypermethylation.

Conclusion

Observing similar level of APC promoter hypermethylation in patients with SCCE in this high risk region and comparing it with other parts of the world could support the hypothesis that a common molecular mechanism might be involved in tumorigenesis of SCCE. In addition, the higher rate of two-year survival for patients with unmethylated APC promoter as well as its relationship with tumor differentiation would suggest that this tumor suppressor could be an appropriate candidate molecular marker for evaluating tumor malignancy and predicting survival of patients subsequent to treatment.

Epigenetic inactivation of the canonical Wnt antagonist SRY-box containing gene 17 in colorectal cancer

SRY-box containing gene 17 (Sox17) is a member of the high mobility group (HMG) transcription factor superfamily, which plays critical roles in the regulation of development and stem/precursor cell function, at least partly through repression of Wnt pathway activity. Modulators controlling aberrant Wnt signaling activation are frequently disrupted in human cancers through complementary effects of epigenetic and genetic changes. Our recent global analysis of CpG island hypermethylation and gene expression in colorectal cancer (CRC) cell lines revealed that SOX17 gene silencing is associated with DNA hypermethylation of a CpG island in the promoter region. Here, we report that CpG island methylation-dependent silencing of SOX17 occurs in 100% of CRC cell lines, 86% of colorectal adenomas, 100% of stage I and II CRC, 89% of stage III CRC, 89% of primary esophageal cancer, and 50% of non-small cell lung cancer. Overexpression of SOX17 in HCT116 CRC cells inhibits colony growth and beta-catenin/T-cell factor-dependent transcription. Structure-based deletion analysis further shows the presence of a Wnt signaling repression domain in the SOX17 HMG box. Together, our studies suggest that SOX17 is a negative modulator of canonical Wnt signaling, and that SOX17 silencing due to promoter hypermethylation is an early event during tumorigenesis and may contribute to aberrant activation of Wnt signaling in CRC.

Targeting the Wnt signaling pathway to treat Barrett’s esophagus

Barrett's esophagus (BE) is an acquired condition in which the normal squamous epithelium in the distal esophagus is replaced by a metaplastic columnar epithelium, as a complication of chronic gastroesophageal reflux. The clinical significance of this disease is its associated predisposition to esophageal adenocarcinoma (EAC). Recently, and similarly to other human malignancies, the Wnt signaling pathway and its key component beta-catenin have been implicated in the carcinogenesis of BE. Although mutations in adenomatous polyposis coli (APC) or beta-catenin are rare in EAC, alterations of upstream components, such as overexpression of Wnt2 ligand or downregulation of Wnt antagonists may play dominant roles in the activation of the Wnt pathway. Increasing evidence suggests that inhibiting the Wnt pathway may be a new targeted therapy for the treatment of cancers and could, therefore, be promising for the cure of EAC, which remains a highly lethal disease.

Differences in the histological findings, phenotypic marker expressions and genetic alterations between adenocarcinoma of the gastric cardia and distal stomach

Adenocarcinoma of the gastric cardia (C-Ca) is possibly a specific subtype of gastric carcinoma. The purpose of this study was to clarify the differences in the clinicopathological characteristics between C-Ca and adenocarcinoma of the distal stomach (D-Ca), and also the differences in the expressions of gastric and intestinal phenotypic markers and genetic alterations between the two. The clinicopathological findings in 72 cases with C-Ca were examined and compared with those in 170 cases with D-Ca. The phenotypic marker expressions examined were those of human gastric mucin (HGM), MUC6, MUC2 and CD10. Furthermore, the presence of mutations in the APC, K-ras and p53 genes and the microsatellite instability status of the tumour were also determined. C-Ca was associated with a significantly higher incidence of differentiated-type tumours and lymphatic vessel invasion (LVI) as compared with D-Ca (72.2 vs 48.2%, P=0.0006 and 72.2 vs 55.3%, P=0.0232, respectively). Oesophageal invasion by the tumour beyond the oesophago-gastric junction (OGJ) was found in 56.9% of cases with C-Ca; LVI in the area of oesophageal invasion was demonstrated in 61% of these cases. Also, LVI was found more frequently in cases of C-Ca with oesophageal invasion than in those without oesophageal invasion (82.9 vs 58.1%, P=0.0197). The incidence of undifferentiated-type tumours was significantly higher in cases with advanced-stage C-Ca than in those with early-stage C-Ca (5 vs 36.5%, P=0.0076). A significantly greater frequency of HGM expression in early-stage C-Ca and significantly lower frequency of MUC2 expression in advanced-stage C-Ca was observed as compared with the corresponding values in cases of D-Ca (78.9 vs 52.2%, P=0.0402 and 51.5 vs 84.6%, P=0.0247, respectively). Mutation of the APC gene was found in only one of all cases of C-Ca, and the frequency of mutation of the APC gene was significantly lower in cases of C-Ca than in those of D-Ca (2.4 vs 20.0%, P=0.0108). The observations in this study suggest that C-Ca is a more aggressive tumour than D-Ca. The differences in biological behavior between C-Ca and D-Ca may result from the different histological findings in the wall of the OGJ and the different genetic pathways involved in the carcinogenesis.

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.

The molecular biology of esophageal adenocarcinoma

BACKGROUND

Barrett's esophagus is an acquired metaplastic change that occurs in the distal esophagus secondary to chronic gastroesophageal reflux. This premalignant condition forms the most important risk factor for developing esophageal adenocarcinoma, which is an extremely aggressive tumor with a 5-year survival rate of less than 25%. Carcinomas that arise in the setting of Barrett's esophagus are thought to develop as part of the metaplasia-dysplasia-carcinoma sequence.

OBJECTIVE

To review the current knowledge on the genomic alterations involved in the development of Barrett's esophagus and its progression to dysplasia and/or cancer.

RESULTS

Several changes in gene structure, gene expression, and protein structure are associated with the progression of Barrett's esophagus to adenocarcinoma. Accumulation of these changes seems to be essential, rather than the exact sequence of these changes. Multiple molecular pathways are involved and interact with each other. Alterations in tumor suppressor genes, amongst which p53 and p16, are early events in the metaplasia-dysplasia-adenocarcinoma sequence, followed by loss of cell cycle checkpoints. Ongoing genomic instability leads to cumulative genetic errors and thereby the generation of multiple clones of transformed cells.

CONCLUSIONS

Within the multistep process of esophageal adenocarcinogenesis, to date no single molecular marker came forward able to predict who will and who will not develop cancer in the setting of Barrett's esophagus. Instead, panels of markers need to be developed in the future allowing to indicate disease progression. Identification of crucial molecular pathways involved in esophageal adenocarcinogenesis would ultimately improve therapy and facilitate development of new treatment strategies.

Loss of Heterozygosity and Immunohistochemistry of Adenocarcinomas of the Esophagus and Gastric Cardia

PURPOSE

Adenocarcinomas of the distal esophagus and gastric cardia are two tumors that have many features in common. They have similar prognoses, treatment modalities, and patterns of dissemination. The etiology is different, with gastroesophageal reflux disease playing a major role for esophageal adenocarcinoma, in contrast to adenocarcinoma of the gastric cardia. In the present study, we investigated several genetic and immunohistochemical features of adenocarcinomas of the distal esophagus and gastric cardia.

EXPERIMENTAL DESIGN

Sixty-two resection specimens of either adenocarcinoma of the esophagus or adenocarcinoma of the gastric cardia were carefully selected. The genetic analysis included loss of heterozygosity of several tumor suppressor genes known to be involved in esophagogastric carcinogenesis. Immunohistochemical studies included the analysis of p53, c-Met, c-erbB-2, beta-catenin, and cyclooxygenase-2. In addition, a mutation analysis of the Tcf1 gene was done by direct sequencing.

RESULTS

Patients with cardiac carcinoma had a significantly worse tumor stage and poorer differentiation on histology. Loss of heterozygosity analysis did not reveal significant differences between esophageal adenocarcinoma and cardiac adenocarcinoma. Immunohistochemical analysis revealed significantly more nuclear accumulation of beta-catenin and overexpression of cyclooxygenase-2 in patients with esophageal adenocarcinoma, compared with patients with cardiac carcinoma. No mutation was found in the Tcf1 gene in either tumor type.

CONCLUSIONS

Although adenocarcinomas of the distal esophagus and gastric cardia have many features in common, we have found some evidence that they might form two different entities.

Biomarkers of esophageal adenocarcinoma and Barrett's esophagus

The rising incidence and poor prognosis of esophageal adenocarcinoma in the Western world have intensified research efforts into earlier methods of detection of this disease and its relationship to Barrett's esophagus. The progression of Barrett's esophagus to adenocarcinoma has been the focus of particular scrutiny, and a number of potential tissue and serum-based disease biomarkers have emerged. The epidemiology and pathogenesis of esophageal adenocarcinoma are outlined. Tissue biomarkers allowing risk stratification of Barrett's are reviewed as well as strategies currently being used to discover novel biomarkers that will facilitate the early detection of esophageal adenocarcinoma. Finally, the uses of biomarkers as predictive tests for targeted treatments and as surrogate endpoints in chemoprevention trials are considered.

Frequent loss of the AXIN1 locus but absence of AXIN1 gene mutations in adenocarcinomas of the gastro-oesophageal junction with nuclear beta-catenin expression

Up to 60% of gastro-oesophageal junction (GEJ) adenocarcinomas show nuclear β-catenin expression, pointing to activated T-cell factor (TCF)/β-catenin-driven gene transcription. We demonstrate in five human GEJ adenocarcinoma cell lines that nuclear β-catenin expression indeed correlates with enhanced TCF-mediated transcription of a reporter gene. In several tumour types, TCF/β-catenin activation is caused by mutations in either adenomatous polyposis coli (APC), β-catenin exon 3, AXIN1, AXIN2 or β-transducin repeat-containing protein (β-TrCP). In GEJ adenocarcinomas, very few APC and β-catenin mutations have been found. Therefore, the mechanism of Wnt pathway activation remains unclear. In the present study, we did not find AXIN1 gene mutations in 17 GEJ tumours with nuclear β-catenin expression (without β-catenin exon 3 mutations). Six intragenic single nucleotide polymorphisms (SNPs) were identified. One of these, the AXIN1 gene T1942C SNP, has a frequency of 21% but is only very recently described despite numerous AXIN1 gene mutational studies. We provide evidence why this SNP was missed in single strand conformation polymorphism analyses. The AXIN1 gene G2063A variation was previously described as a gene mutation but we demonstrate that this is a polymorphism. With these six SNPs loss of heterozygosity (LOH) was found in 11 of 15 (73%) informative tumours. To investigate a possible AXIN1 gene dosage effect in GEJ tumours expressing nuclear β-catenin, AXIN1 locus LOH was determined in 20 tumours expressing membranous and no nuclear β-catenin. LOH was found in 10 of 13 (77%) informative cases. AXIN1 protein immunohistochemistry revealed cytoplasmic expression in all tumours irrespective of the presence of AXIN1 locus LOH. These data indicate that nuclear β-catenin expression is indicative for activated Wnt signalling and that neither AXIN1 gene mutations nor AXIN1 locus LOH are involved in Wnt pathway activation in GEJ adenocarcinomas.

Down-regulation of beta catenin inhibits the growth of esophageal carcinoma cells

INTRODUCTION

Esophageal cancer remains a highly lethal malignancy, with therapeutic options of limited efficacy in the majority of patients. Understanding the molecular events involved in the pathogenesis of esophageal cancer offers insight into potential targets for treatment. Beta catenin and Wnt signaling abnormalities are involved in the development of both adenocarcinoma and squamous carcinoma of the esophagus. We hypothesized that down-regulation of beta catenin would inhibit the growth of human esophageal cancer.

METHODS

A human esophageal squamous cell carcinoma cell line (TE10) was treated with phosphorothioate antisense oligonucleotides to beta catenin. The cells were subsequently assayed for beta catenin mRNA and protein by real-time polymerase chain reaction and Western blot. Beta catenin transcriptional activity was determined by TOPFlash assay. Cell viability and growth was assessed by methyl-thiazol-diphenyl-tetrazolium assay and trypan blue exclusion. A colorimetric assay was employed to assess caspase 3 activity, and flow cytometry was done to determine percentage of cells in a given phase of the cell cycle.

RESULTS

Following antisense treatment, beta catenin mRNA and protein concentration were decreased. There was corresponding decrease in beta catenin-transcription factor-dependent transcription. Treatment with beta catenin antisense resulted in significantly decreased cell viability and proliferation. The mechanism appears to be increased induction of apoptosis.

CONCLUSIONS

These data suggest a potential role for the targeting of beta catenin in the treatment of esophageal cancer.

Adenomatous polyposis coli gene, beta-catenin, and E-cadherin expression in proximal and distal gastric cancers and precursor lesions: an immunohistochemical study using tissue microarrays

The aims of this study were (1) to compare protein expression of adenomatous polyposis coli (APC) gene, beta-catenin, and E-cadherin between proximal and distal gastric adenocarcinomas and (2) to investigate their use as markers of cancer risk in intestinal metaplasia (IM). The epidemiology of proximal (cardia and gastroesophageal junction) and distal (antrum and corpus) gastric carcinomas is strikingly different despite similar morphologies. Carcinoma of the distal stomach is decreasing in incidence, whereas proximal carcinomas are increasing in incidence more than any other cancer in the Western world. This phenomenon has so far not been satisfactorily explained. IM is a well-established precursor for adenocarcinoma in the distal stomach but less so in the proximal stomach. However, its specificity as a predictor of gastric carcinoma is very low. Abnormalities of APC, beta-catenin, and E-cadherin are implicated in carcinogenesis of the stomach and may show aberrant expression at early stages of the neoplastic process. This study evaluated their immunoprofiles in 3 groups: biopsies showing normal mucosa (n = 108), biopsies showing IM (n = 99), and gastric cancer resections (n = 117). In the last group, carcinoma and noninvolved mucosa were studied. All groups included material from both proximal and distal locations. The results of this study showed that there were no differences between proximal and distal locations with regard to APC, beta-catenin, or E-cadherin expression. In both locations, high normal expression rates for all 3 molecules were present in biopsies showing normal gastric mucosa or IM and noninvolved mucosa from gastric cancer resections. In carcinomas, there was a significant decrease in both APC and E-cadherin expression, whereas beta-catenin showed abnormal cytoplasmic and nuclear staining. Diffuse-type cancers showed significantly lower E-cadherin expression than intestinal types. Noninvolved mucosa from cancer resections showed normal APC, beta-catenin, and E-cadherin expression regardless of adjacent tumor type and whether the mucosa was morphologically normal or showed IM. In conclusion, proximal and distal gastric carcinomas show no differences in expression of APC, beta-catenin, or E-cadherin; thus, the observed abnormalities do not seem to contribute to the observed epidemiologic differences between these tumors. Because loss of APC, decreased E-cadherin, or abnormal beta-catenin expression did not occur in IM, even when associated with carcinoma these immunostains are unlikely to be of value in the assessment of malignant potential in IM.

Caught up in a Wnt storm: Wnt signaling in cancer

The Wnt signaling pathway, named for its most upstream ligands, the Wnts, is involved in various differentiation events during embryonic development and leads to tumor formation when aberrantly activated. Molecular studies have pinpointed activating mutations of the Wnt signaling pathway as the cause of approximately 90% of colorectal cancer (CRC), and somewhat less frequently in cancers at other sites, such as hepatocellular carcinoma (HCC). Ironically, Wnts themselves are only rarely involved in the activation of the pathway during carcinogenesis. Mutations mimicking Wnt stimulation-generally inactivating APC mutations or activating beta-catenin mutations-result in nuclear accumulation of beta-catenin which subsequently complexes with T-cell factor/lymphoid enhancing factor (TCF/LEF) transcription factors to activate gene transcription. Recent data identifying target genes has revealed a genetic program regulated by beta-catenin/TCF controlling the transcription of a suite of genes promoting cellular proliferation and repressing differentiation during embryogenesis, carcinogenesis, and in the post-embryonic regulation of cell positioning in the intestinal crypts. This review considers the spectra of tumors arising from active Wnt signaling and attempts to place perspective on recent data that begin to elucidate the mechanisms prompting uncontrolled cell growth following induction of Wnt signaling.

The Wnt signaling pathway and its role in tumor development

Cancer development depends on the aberrant activation of signal transduction pathways that control cell growth and survival and play important roles in normal embryonic development. This review will focus on one of the most powerful pathways, the canonical Wnt signal transduction cascade, which has been originally described in vertebrate and non-vertebrate embryogenesis and subsequently associated with the development of a multitude of different tumor types, mainly of gastrointestinal origin. In recent years, a variety of novel interacting components and functions have been identified in the Wnt pathway revealing not only the complexity of Wnt signaling but also its potency. Here we will concentrate on the role of the Wnt pathway in cancer development with emphasis placed on the molecular defects known to promote neoplastic transformation in humans and in animal models.

Immunohistochemical profile of common epithelial neoplasms arising in the kidney

To distinguish common epithelial tumors arising in the kidney may have significant implications, in terms of molecular ontogeny and prognosis. It is important to investigate the distribution of immunoexpression of commonly used markers among renal neoplasms and to develop a useful panel as an adjunct to histologic examination, which could lead to the accurate diagnosis of both primary and metastatic tumors. Immunohistochemical stains for CD10, vimentin (VIM), E-cadherin (E-CD), cytokeratins (CK) 7, 8, 19, and 20, high molecular weight keratin (HCK), and peanut lectin agglutinin (PL) (Arachis hypogaea) were performed on 45 (96 for CK7, CK20) conventional (CC), 20 papillary (PC), and 6 (24 for CK7, CK20) chromophobe renal carcinomas (CPC); 12 oncocytomas (OC); 5 collecting duct carcinomas (CDC), and 25 urothelial carcinomas of the renal pelvis (UC). Reactivity for CD10 was evaluated on the basis of the presence of cell surface staining; that for all CKs, cytoplasmic/membranous staining; and that for PL, luminal staining. Both CD10 and VIM were predominantly expressed in CC and PC; E-CD in CPC, OC, and UC; CK7 in PC, CPC, and UC; CK8 and CK19 in CDC and UC; CK20 in UC; HCK in CDC and UC; and PL in CDC. CC and OC were predominantly CK7-/CK20-; PC, CK7+/20-; CPC, CK7+/CK20- or CK7-/CK20-; and UC, CK7+/CK20- or CK7+/CK20+. CDC showed slight predominance of CK7-/20- over CK7+/CK20-. CC was most frequently CD10+/CK7-/HCK-/PL-; PC, CD10+/CK7+/HCK-/PL-; CPC, CD10-/CK7+/HCK-/PL-; OC, CD10-/CK7-/HCK-/ PL-; CDC, CD10-/CK7+/HCK-/PL+ or CD10-/CK7-/ HCK+/PL+; and UC, CD10-/CK7+/HCK+/PL-. Discriminant analysis suggested that CD10/CK7/HCK/PL may be a useful primary immunopanel for distinguishing among CC, PC, CDC, and UC.

Beta-catenin expression and its association with prognostic factors in adenocarcinoma developed in Barrett esophagus

The majority of the adenocarcinomas arising in Barrett esophagus manifest clinically at an advanced stage and have a poor prognosis. As a result of this poor prognosis, much attention has been directed toward the exploration of markers for neoplastic progression in Barrett esophagus. The objective of the present study was to determine the expression of beta-catenin by immunohistochemical analysis in 70 adenocarcinomas developed in Barrett esophagus and to examine its relationship to various prognostic factors currently in use. Abnormal beta-catenin expression, consisting of the loss of membranous staining and the appearance of the nuclear staining, was found in 43 cases (61%). Of patients with the 43 tumors showing abnormal beta-catenin expression, 25 (58%) survived more than 1 year. In contrast, only 7 (26%) of 27 patients with tumors showing normal beta-catenin expression survived longer than 1 year. Most of the superficial (Tis-T1) tumors (83% [10/12]) exhibited abnormal beta-catenin expression compared with only 53% (31/58) in the T2-T3 group. These results suggest a possible correlation among beta-catenin expression, tumor stage, and length of survival as prognostic factors in patients with adenocarcinoma in Barrett esophagus.

Superficial fibromatoses are genetically distinct from deep fibromatoses

Whereas deep fibromatoses (abdominal, extra-abdominal, mesenteric) display locally aggressive behavior, superficial fibromatoses typically remain small and less likely to recur despite essentially identical morphology. Somatic beta-catenin or APC gene mutations have been reported in < or =74% of sporadic deep fibromatoses and in virtually 100% of Gardner syndrome-associated fibromatoses, whereas genetic events in superficial fibromatoses remain less well characterized. We performed immunohistochemical staining for beta-catenin on 29 superficial fibromatoses (22 palmar, 5 plantar, 1 penile, and 1 infantile digital fibromatosis) and 5 deep fibromatoses. Mutations of beta-catenin and APC genes were analyzed in cases of superficial fibromatoses by direct DNA sequencing of the beta-catenin gene on Exon 3 encompassing the GSK-3 36 phosphorylation region and of the APC gene on the mutation cluster region. Nuclear accumulation of beta-catenin was present in 86% (25/29) of superficial fibromatosis cases ranging from 5 to 100% of nuclei (mean, 13%; median, 10%), though in a minority of nuclei in most examples. Deep fibromatoses had 60 to 100% nuclear staining in all five cases. No somatic mutations of beta-catenin or APC genes were identified in any of the superficial fibromatoses. In contrast to deep fibromatoses, superficial fibromatoses lack beta-catenin and APC gene mutations; the significance of focal nuclear beta-catenin accumulation is unclear. This difference may account inpart for their divergent clinical manifestations despite their morphologic resemblance to deep fibromatoses.