Genetic differences between adenocarcinomas arising in Barrett's esophagus and gastric mucosa

Pan-caner analysis identifies PSMA7 as a targets for amplification at 20q13.33 in tumorigenesis

The chromosome 20 long arm (20q) is one of the genomic hotspots where copy number alterations frequently occur in multiple types of tumors. However, it remains elusive which genes are implicated in 20q-related tumorigenesis. Here, by querying TCGA and GEO databases, we observed frequent copy number amplification at 20q and the chromosome subband 20q13.33 was amplificated in multiple cancers. Among those genes at 20q13.33, PSMA7 was found with the strongest correlation with cancers. Further analysis revealed that PSMA7 amplification was the most frequent genetic alteration event conferring adverse prognosis in various cancers. Consistent with the strong positive correlation between PSMA7 amplification and gene expression, elevated PSMA7 expression was observed in 20 of 33 types of cancers with a close link to adverse outcomes in certain tumors. In addition, PSMA7 was essential for the growth of almost 1095 cancer lines. Mechanistically, aberrant PSMA7 most probably influenced the proteasome and protease-related pathways to promote tumorigenesis and might be antagonized by several compounds, e.g., Docetaxel in relevant cancers. The current in-depth pan-cancer analysis refines our understanding of the crucial oncogenic role of copy number amplifications at PSMA7 loci at the novel chromosome amplicon 20q13.33 across different tumors.

Key Molecules of Fatty Acid Metabolism in Gastric Cancer

Fatty acid metabolism is closely linked to the progression of gastric cancer (GC), a very aggressive and life-threatening tumor. This study examines linked molecules, such as Sterol Regulatory Element-Binding Protein 1 (SREBP1), ATP Citrate Lyase (ACLY), Acetyl-CoA Synthases (ACSs), Acetyl-CoA Carboxylase (ACC), Fatty Acid Synthase (FASN), Stearoyl-CoA Desaturase 1 (SCD1), CD36, Fatty Acid Binding Proteins (FABPs), and Carnitine palmitoyltransferase 1 (CPT1), as well as their latest studies and findings in gastric cancer to unveil its core mechanism. The major enzymes of fatty acid de novo synthesis are ACLY, ACSs, ACC, FASN, and SCD1, while SREBP1 is the upstream molecule of fatty acid anabolism. Fatty acid absorption is mediated by CD36 and FABPs, and fatty acid catabolism is mediated by CPT1. If at all possible, we will discover novel links between fatty acid metabolism and a prospective gastric cancer target.

Evidence that polyploidy in esophageal adenocarcinoma originates from mitotic slippage caused by defective chromosome attachments

Polyploidy is present in many cancer types and is increasingly recognized as an important factor in promoting chromosomal instability, genome evolution, and heterogeneity in cancer cells. However, the mechanisms that trigger polyploidy in cancer cells are largely unknown. In this study, we investigated the origin of polyploidy in esophageal adenocarcinoma (EAC), a highly heterogenous cancer, using a combination of genomics and cell biology approaches in EAC cell lines, organoids, and tumors. We found the EAC cells and organoids present specific mitotic defects consistent with problems in the attachment of chromosomes to the microtubules of the mitotic spindle. Time-lapse analyses confirmed that EAC cells have problems in congressing and aligning their chromosomes, which can ultimately culminate in mitotic slippage and polyploidy. Furthermore, whole-genome sequencing, RNA-seq, and quantitative immunofluorescence analyses revealed alterations in the copy number, expression, and cellular distribution of several proteins known to be involved in the mechanics and regulation of chromosome dynamics during mitosis. Together, these results provide evidence that an imbalance in the amount of proteins implicated in the attachment of chromosomes to spindle microtubules is the molecular mechanism underlying mitotic slippage in EAC. Our findings that the likely origin of polyploidy in EAC is mitotic failure caused by problems in chromosomal attachments not only improves our understanding of cancer evolution and diversification, but may also aid in the classification and treatment of EAC and possibly other highly heterogeneous cancers.

ASCL1-regulated DARPP-32 and t-DARPP stimulate small cell lung cancer growth and neuroendocrine tumour cell proliferation

Background

Small cell lung cancer (SCLC) is the most aggressive form of lung cancer, and new molecular insights are necessary for prognostic and therapeutic advances.

Methods

Dopamine and cAMP-regulated phosphoprotein, Mr 32000 (DARPP-32) and its N-terminally truncated splice variant, t-DARPP, were stably overexpressed or ablated in human DMS-53 and H1048 SCLC cells. Functional assays and immunoblotting were used to assess how DARPP-32 isoforms regulate SCLC cell growth, proliferation, and apoptosis. DARPP-32-modulated SCLC cells were orthotopically injected into the lungs of SCID mice to evaluate how DARPP-32 and t-DARPP regulate neuroendocrine tumour growth. Immunostaining for DARPP-32 proteins was performed in SCLC patient-derived specimens. Bioinformatics analysis and subsequent transcription assays were used to determine the mechanistic basis of DARPP-32-regulated SCLC growth.

Results

We demonstrate in mice that DARPP-32 and t-DARPP promote SCLC growth through increased Akt/Erk-mediated proliferation and anti-apoptotic signalling. DARPP-32 isoforms are overexpressed in SCLC patient-derived tumour tissue, but undetectable in physiologically normal lung. Achaete-scute homologue 1 (ASCL1) transcriptionally activates DARPP-32 isoforms in human SCLC cells.

Conclusions

We reveal new regulatory mechanisms of SCLC oncogenesis that suggest DARPP-32 isoforms may represent a negative prognostic indicator for SCLC and serve as a potential target for the development of new therapies.

DARPP-32: from neurotransmission to cancer

Dopamine and cAMP-regulated phosphoprotein Mr 32,000 (DARPP-32), also known as phosphoprotein phosphatase-1 regulatory subunit 1B (PPP1R1B), was initially discovered as a substrate of dopamine-activated protein kinase A (PKA) in the neostriatum in the brain. While phosphorylation at Thr-34 by PKA converts DARPP-32 into a potent inhibitor of protein phosphatase 1 (PP1), phosphorylation at Thr-75 transforms DARPP-32 into an inhibitor of PKA. Through regulation of DARPP-32 phosphorylation and modulation of protein phosphatase and kinase activities, DARPP-32 plays a critical role in mediating the biochemical, electrophysiological, and behavioral effects controlled by dopamine and other neurotransmitters in response to drugs of abuse and psychostimulants. Altered expression of DARPP-32 and its truncated isoform (t-DARPP), specifically in the prefrontal cortex, has been associated with schizophrenia and bipolar disorder. Moreover, cleavage of DARPP-32 by calpain has been implicated in Alzheimer's disease. Amplification of the genomic locus of DARPP-32 at 17q12 has been described in several cancers. DARPP-32 and t-DARPP are frequently overexpressed at the mRNA and protein levels in adenocarcinomas of the breast, prostate, colon, and stomach. Several studies demonstrated the pro-survival, pro-invasion, and pro-angiogenic functions of DARPP-32 in cancer. Overexpression of DARPP-32 and t-DARPP also promotes chemotherapeutic drug resistance and cell proliferation in gastric and breast cancers through regulation of pro-oncogenic signal transduction pathways. The expansion of DARPP-32 research from neurotransmission to cancer underscores the broad scope and implication of this protein in disparate human diseases.

Integrated molecular analysis reveals complex interactions between genomic and epigenomic alterations in esophageal adenocarcinomas

The incidence of esophageal adenocarcinoma (EAC) is rapidly rising in the United States and Western countries. In this study, we carried out an integrative molecular analysis to identify interactions between genomic and epigenomic alterations in regulating gene expression networks in EAC. We detected significant alterations in DNA copy numbers (CN), gene expression levels, and DNA methylation profiles. The integrative analysis demonstrated that altered expression of 1,755 genes was associated with changes in CN or methylation. We found that expression alterations in 84 genes were associated with changes in both CN and methylation. These data suggest a strong interaction between genetic and epigenetic events to modulate gene expression in EAC. Of note, bioinformatics analysis detected a prominent K-RAS signature and predicted activation of several important transcription factor networks, including β-catenin, MYB, TWIST1, SOX7, GATA3 and GATA6. Notably, we detected hypomethylation and overexpression of several pro-inflammatory genes such as COX2, IL8 and IL23R, suggesting an important role of epigenetic regulation of these genes in the inflammatory cascade associated with EAC. In summary, this integrative analysis demonstrates a complex interaction between genetic and epigenetic mechanisms providing several novel insights for our understanding of molecular events in EAC.

Linkage and related analyses of Barrett's esophagus and its associated adenocarcinomas

Background

Familial aggregation and segregation analysis studies have provided evidence of a genetic basis for esophageal adenocarcinoma (EAC) and its premalignant precursor, Barrett's esophagus (BE). We aim to demonstrate the utility of linkage analysis to identify the genomic regions that might contain the genetic variants that predispose individuals to this complex trait (BE and EAC).

Methods

We genotyped 144 individuals in 42 multiplex pedigrees chosen from 1000 singly ascertained BE/EAC pedigrees, and performed both model‐based and model‐free linkage analyses, using S.A.G.E. and other software. Segregation models were fitted, from the data on both the 42 pedigrees and the 1000 pedigrees, to determine parameters for performing model‐based linkage analysis. Model‐based and model‐free linkage analyses were conducted in two sets of pedigrees: the 42 pedigrees and a subset of 18 pedigrees with female affected members that are expected to be more genetically homogeneous. Genome‐wide associations were also tested in these families.

Results

Linkage analyses on the 42 pedigrees identified several regions consistently suggestive of linkage by different linkage analysis methods on chromosomes 2q31, 12q23, and 4p14. A linkage on 15q26 is the only consistent linkage region identified in the 18 female‐affected pedigrees, in which the linkage signal is higher than in the 42 pedigrees. Other tentative linkage signals are also reported.

Conclusion

Our linkage study of BE/EAC pedigrees identified linkage regions on chromosomes 2, 4, 12, and 15, with some reported associations located within our linkage peaks. Our linkage results can help prioritize association tests to delineate the genetic determinants underlying susceptibility to BE and EAC.

Genetic Insights in Barrett's Esophagus and Esophageal Adenocarcinoma

Beginning in the 1980s, an alarming rise in the incidence of esophageal adenocarcinoma (EA) led to screening of patients with reflux to detect Barrett's esophagus (BE) and surveillance of BE to detect early EA. This strategy, based on linear progression disease models, resulted in selective detection of BE that does not progress to EA over a lifetime (overdiagnosis) and missed BE that rapidly progresses to EA (underdiagnosis). Here we review the historical thought processes that resulted in this undesired outcome and the transformation in our understanding of genetic and evolutionary principles governing neoplastic progression that has come from application of modern genomic technologies to cancers and their precursors. This new synthesis provides improved strategies for prevention and early detection of EA by addressing the environmental and mutational processes that can determine "windows of opportunity" in time to detect rapidly progressing BE and distinguish it from slowly or nonprogressing BE.

Different roles for p16(INK) (4a) -Rb pathway and INK4a/ARF methylation between adenocarcinomas of gastric cardia and distal stomach

BACKGROUND AND AIM

The incidence of distal gastric adenocarcinoma has significantly decreased, but gastric cardia adenocarcinoma has been on the rise. Cardia adenocarcinoma might be a specific entity distinct from the carcinoma of the rest stomach. The aim was to explore putative differences in p16(INK) (4a) -retinoblastoma (Rb) pathway and INK4a/ARF methylation between gastric cardia and distal adenocarcinomas.

METHODS

Ninety-six cardia adenocarcinomas and 79 distal samples were analyzed for comparing p16(INK) (4a) -Rb expressions, INK4a/ARF deletion, and methylation using immunohistochemistry, polymerase chain reaction, and methylation-specific polymerase chain reaction.

RESULTS

The expression of p16(INK) (4a) in cardia adenocarcinoma (43.2%) was significantly lower than in distal cases (75.0%, P < 0.05). As well, cardia adenocarcinoma showed lower expression of p14(ARF) compared with distal cases (34.1% vs 57.5%, P < 0.05). The incidence of p16(INK) (4a) deletion was 20.5% and 15.0%, while p14(ARF) deletion was 18.2% and 10.0% in cardia and distal adenocarcinomas, respectively, showing no significant differences between two entities. However, the incidences of p14(ARF) and p16(INK) (4a) methylation in cardia adenocarcinoma were significantly higher than in distal samples (p14(ARF) : 61.5% vs 43.6%; p16(INK) (4a) : 73.1% vs 51.3%, P < 0.05). INK4a/ARF methylations were more prevalent in poorly differentiated cardia carcinoma compared with poorly differentiated distal cases.

CONCLUSIONS

There were differences in p16(INK) (4a) -Rb immunotypes and INK4a/ARF methylation between two entities, indicating that cardia adenocarcinoma may be different in cell proliferation, differentiation, and gene biomarkers compared with distal gastric adenocarcinoma.

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.

AURKA governs self-renewal capacity in glioma-initiating cells via stabilization/activation of β-catenin/Wnt signaling

Glioma-initiating cells (GIC), which are characterized by their self-renewal capacity and tumorigenicity, were recently identified as a highly tumorigenic subpopulation of glioblastoma multiforme and are considered responsible for glioblastoma recurrence and chemo/radiation resistance. Previously, it was revealed that Wnt signaling activation is critical to the self-renewal of GICs. However, the molecular mechanism underlying the high expression of β-catenin, the key transcription factor of the Wnt signaling pathway, remains elusive. In this investigation, it was determined that aurora kinase A (AURKA) regulates the self-renewal and tumorigenicity of GICs by stabilizing β-catenin. In GICs, AURKA directly interacts with AXIN and disrupts the AXIN/GSK3β/β-catenin destruction complex and stabilizes β-catenin, thereby activating Wnt signaling to promote self-renewal. Stable knockdown of AURKA destabilizes β-catenin by increasing phosphorylated β-catenin bound to AXIN and suppresses Wnt signaling, which inhibits the ability of GICs to self-renew. This effect is rescued by expression of an AURKA kinase dead mutant, D274A, which lacks the ability to phosphorylate GSK3β, indicating that stabilization of β-catenin by AURKA in GICs is independent from phosphorylation of GSK3β. Functional experiments confirm that inhibition of AUKRA in GICs could suppress their "stemness," self-renewal ability, and tumorigenicity both in vitro and in vivo, and these effects could be rescued by stabilized β-catenin mutant. These findings indicate that AURKA competes away the binding of AXIN from β-catenin, induces β-catenin stabilization, and activates Wnt signaling in GICs.

IMPLICATIONS

AURKA kinase inhibition could effectively attenuate Wnt signaling, thereby inhibiting the self-renewal and tumorigenicity of GICs, and may be a novel target for glioblastoma treatment strategies.

Different expression pattern and significance of p14ARF-Mdm2-p53 pathway and Bmi-1 exist between gastric cardia and distal gastric adenocarcinoma

Recent studies have suggested that adenocarcinoma of gastric cardia (GCA) is distinct from distal stomach, with different risk factors, tumor characteristics, and biological behavior. The aim of this study is to evaluate the possible difference in the expressions of p14ARF, Mdm2, p53, and Bmi-1 by immunohistochemical staining on paraffin-embedded tissues of gastric cardia adenocarcinoma (GCA; n = 74) and distal gastric adenocarcinoma (DGA; n = 41). The results showed that the percentage of p14ARF-negative expression, Mdm2 overexpression, p53-positive expression, and p53 pathway abnormality (p14ARF(-)/Mdm2(+)/p53(+)) were all significantly higher in GCA than those in DGA (P < .05). Further analysis showed that in GCA, the negative expression of p14ARF was significantly associated with poor differentiation, Mdm2 overexpression with tumor stage and lymph node metastasis, and positive p53 expression with tumor stage (P < .05), whereas in DGA, only Mdm2 overexpression was related with well/moderate differentiation (P < .05). Abnormality of the p53 pathway was significantly correlated with poorer differentiation only in GCA (P < .05). The positive expression of Bmi-1 in all cases of GCA and DGA was significantly higher than normal gastric mucosa epithelium, but no difference was found between GCA and DGA (P > .05). Thus, the results in this study confirmed that different expression pattern and clinicopathologic significance of the p14ARF-Mdm2-p53 pathway did exist between GCA and DGA. The results further support the hypothesis that different mechanisms may be involved in the development and progression of adenocarcinoma from cardia and distal portion of stomach.

Meta-analysis demonstrates that the NAD(P)H: quinone oxidoreductase 1 (NQO1) gene 609 C>T polymorphism is associated with increased gastric cancer risk in Asians

The association between the NAD(P)H: quinone oxidoreductase 1 (NQO1) gene C609T polymorphism and gastric cancer has been widely evaluated, yet with conflicting results. Data were available from seven study populations involving 2600 subjects. Overall, comparison of alleles 609T and 609C indicated a significantly increased risk (46%) for gastric cancer (95% confidence interval (95%CI) for odds ratio (OR) = 1.20-1.79) in individuals with the T allele. The tendency was increased in the homozygous comparison (609TT versus 609CC), with an OR = 2.04 (95%CI = 1.37-3.05). Stratified analysis by study design demonstrated stronger associations in population-based studies than in hospital-based studies, based on OR. Ethnicity-based analysis demonstrated a significant association in Asians but not in Caucasians. Additionally, in the subgroup analyses by the type of gastric cancer, a significantly increased risk was found with all genetic models in the gastric adenocarcinoma subgroup compared to the others. We conclude that the NQO1 gene C609T polymorphism increases the risk for gastric cancer, especially in Asian populations.

Angiogenesis-related agents in esophageal cancer

INTRODUCTION

Esophageal cancer is an aggressive disease with poor prognosis. The majority of the patients are diagnosed at an advanced stage and many with early stage disease will develop recurrent disease.

AREAS COVERED

Angiogenesis is essential to the progress and aggressiveness of solid malignancies. Success of anti-angiogenic therapy in colorectal, lung and breast cancers is a proof of principle. Thus far, evidence for benefit from anti-angiogenic therapy in esophageal cancer is lacking. Several Phase II trials with different agents have provided mixed results and the only Phase III trial in the esophageal and gastric cancer failed to show that these agents improve overall survival (OS). However, lack of observed benefit could be due to the challenges specific to the management of esophageal cancers as well as issues with the design of clinical trials for anti-angiogenic therapy.

EXPERT OPINION

An understanding of the biology of the esophageal cancer and its management is essential to the development of anti-angiogenic therapy in this disease. This article reviews the management of esophageal cancer and elaborates on the challenges in the development of anti-angiogenic therapy in esophageal cancer. At the end, strategies are proposed for successful development of anti-angiogenic therapy in esophageal cancer.

CHFR: a key checkpoint component implicated in a wide range of cancers

CHFR (Checkpoint with Forkhead-associated and RING finger domains) has been implicated in a checkpoint regulating entry into mitosis. However, the details underlying its roles and regulation are unclear due to conflicting lines of evidence supporting different notions of its functions. We provide here an overview of how CHFR is thought to contribute towards regulating mitotic entry and present possible explanations for contradictory observations published on the functions and regulation of CHFR. Furthermore, we survey key data showing correlations between promoter hypermethylation or down-regulation of CHFR and cancers, with a view on the likely reasons why different extents of correlations have been reported. Lastly, we explore the possibilities of exploiting CHFR promoter hypermethylation status in diagnostics and therapeutics for cancer patients. With keen interest currently focused on the association between hypermethylation of CHFR and cancers, details of how CHFR functions require further study to reveal how its absence might possibly contribute to tumorigenesis.

Esophageal carcinoma advances in treatment results for locally advanced disease: review

The treatment results of patients with locally advanced esophageal carcinomas have evolved since the publication of the first trial of concurrent mitomycin C and 5-fluorouracil with radiotherapy (RT) in 1983. Subsequent studies refined and improved on the concurrent chemotherapy (chemo) with administration of cisplatin and 5-fluorouracil infusion (PF). Chemo (PF) before surgery improved overall survival (OS) in those patients in most of the randomized trials and in meta-analyses. Two courses of PF concurrent with irradiation followed by additional two courses of PF were superior to RT alone without surgery for both groups. Concurrent chemoradiotherapy followed by surgery was found to have statistically improved OS as compared with surgery only in randomized trials and meta-analyses. In most of these studies, it was found that those patients with pathologic complete response to the initial treatment(s) did better than those who had no improvement at all. Current treatment outcome for these diseases is disappointing; newer strategies including induction chemo with the optimal combination, proper dosage of each drug, and proper number of courses before concurrent chemoradiotherapy; improvement in RT; and immunotherapy with or without subsequent surgery are exciting and definitely need to be investigated in prospective randomized trial(s).

An individual coding polymorphism and the haplotype of the SPARC gene predict gastric cancer recurrence

The 5-year survival rate for gastric adenocarcinoma (GA) remains only 40% and biomarkers to identify patients at high risk of tumor recurrence are urgently needed. Secreted protein acidic and rich in cysteine (SPARC) is an extracellular matrix glycoprotein that mediates cell matrix interactions, and upregulation of SPARC can promote tumor progression and metastasis. This study investigated whether single-nucleotide polymorphisms (SNPs) in SPARC impact the prognosis of GA. Blood or formalin-fixed, paraffin-embedded tissues were obtained from 137 GA patients at the University of Southern California and Memorial Sloan-Kettering Cancer Center medical facilities. DNA was isolated and five SNPs in the SPARC 3'-untranslated region (UTR) were evaluated by DNA sequencing or PCR-restriction fragment length polymorphism. Associations between SNPs and time to tumor recurrence (TTR) were analyzed using Kaplan-Meier curves, log-rank tests, and likelihood-ratio test within logistic or Cox regression model as appropriate. Patients carrying at least one G allele of the SPARC rs1059829 polymorphism (GG, AG) showed a median TTR of 3.7 years compared with 2.1 years TTR for patients with AA (hazard ratio (HR) 0.57; P=0.033). In a multivariate analysis adjusted for T and N category as covariates and stratified by race, hospital and chemotherapy, patients with at least one SPARC rs1059829 G allele (GG, AG) remained significantly associated with superior TTR than patients with AA genotype (adjusted P=0.026). In addition, patients harboring the G-A-A haplotype had the highest risk of tumor recurrence (HR 1.892; adjusted P=0.016). Our findings suggest that SPARC 3'-UTR SNPs may be useful in predicting GA patients at increased risk of recurrence.

Differences of immunophenotypic markers and signaling molecules between adenocarcinomas of gastric cardia and distal stomach

During the past decades, the subsites of gastric carcinoma underwent significant changes. The incidence of the adenocarcinoma at distal stomach has been decreased, whereas cardiac adenocarcinoma remained increasing in many countries. The aim of this study was to investigate the differences between gastric cardiac and distal adenocarcinomas. We detected expressions of cytokeratins (cytokeratins 7, 14, 19, and 20) and mucins (mucins 1, 2, and 5AC) by immunohistochemistry and signaling molecules (p38, mitogen-activated protein kinase-interacting kinase 1 (MNK1), extracellular signal-regulated kinase, Jun N-terminal kinase, and phosphoinositide 3 kinase) by reverse transcription-polymerase chain reaction in both groups. The incidence of mucin 2 expression was lower in total (50.0%) and advanced-stage cases (52.0%) with cardiac adenocarcinomas than those in distal cases with total (70.2%) and advanced stage (71.4%), respectively. However, the staining for cytokeratin 14 was also significantly higher in total or advanced-stage tumors from the cardia. Our data showed no significant difference of cytokeratin 7/cytokeratin 20 pattern between 2 groups, but cytokeratin 20 expression was significantly higher in advanced-stage carcinomas of the cardia (58.7%) than in distal ones with advanced stage (38.3%). A multivariate analysis demonstrated different relationships between immunophenotypic markers and pathologic parameters in adenocarcinomas of the cardia and distal stomach. Moreover, significantly lower expressions of MNK1 and p38 in cardiac tumors were also detected. In summary, we found significant differences in patterns of immunophenotypic markers and expressions of signaling molecules between the 2 groups. It is indicated that adenocarcinoma of the cardia was different in histotype and histologic origin from distal adenocarcinoma. The cardiac adenocarcinoma might be a special subtype or an independent entity of gastric carcinoma in China.

Esophageal adenocarcinoma: treatment modalities in the era of targeted therapy

Esophageal adenocarcinoma is an aggressive malignancy with a poor outcome, and its incidence continues to rise at an alarming rate. Current treatment strategies combining chemotherapy, radiation, and surgery are plagued with high rates of recurrence and metastasis. Multiple molecular pathways including the epidermal growth factor receptor, vascular endothelial growth factor, v-erb-b2 erythroblastic leukemia viral oncogene homolog (ERBB2), and Aurora kinase pathways are activated in many esophageal adenocarcinomas. In many cases, these pathways have critical roles in tumor progression. Research on the mechanisms by which these pathways contribute to disease progression has resulted in numerous biologic agents and small molecules with the potential to improve outcome. The promise of targeted therapy and personalized medicine in improving the clinical outcome is now closer than it has ever been.

Epigenetic and genetic silencing of CHFR in esophageal adenocarcinomas

BACKGROUND

The checkpoint with forkhead-associated domain and RING-finger domain (CHFR) is a mitotic checkpoint protein with tumor-suppressor functions. In this study, the authors investigated the epigenetic and genetic mechanisms that regulate CHFR expression in esophageal adenocarcinomas (EACs).

METHODS

Quantitative reverse transcriptase polymerase chain reaction analysis demonstrated downregulation of CHFR transcript in 79% of EACs (44 of 56) compared with 41 normal samples (P < .001). Immunohistochemical analysis of CHFR protein expression showed absence or weak immunostaining for CHFR in 75% of EACs (56 of 75) compared with normal tissue samples. The authors next examined the promoter DNA hypermethylation of CHFR by using quantitative bisulfite pyrosequencing technology. They detected significant CHFR promoter DNA hypermethylation in 31% of tumor samples (18 of 58) compared with normal samples (P < .001). Treatment of OE33 cells with 5-Aza-deoxycytidine led to reduction in the promoter DNA methylation levels with restoration of the CHFR mRNA expression, which confirmed promoter DNA methylation as an epigenetic mechanism regulating CHFR expression. However, they identified several EACs where the CHFR mRNA expression was silenced in the absence of notable methylation. Therefore, the authors examined the relative DNA copy number level of CHFR compared with normal samples.

RESULTS

The results confirmed a decrease or absence of the relative CHFR DNA copy number levels in 59% of tumor samples. Nine tumors that showed loss of CHFR mRNA expression, in absence of promoter DNA hypermethylation, demonstrated a significant loss of relative CHFR DNA copy numbers.

CONCLUSIONS

Taken together, their findings demonstrated that both epigenetic and genetic mechanisms were involved in silencing CHFR expression in EACs.

Genetic profiles of gastroesophageal cancer: combined analysis using expression array and tiling array--comparative genomic hybridization

We aimed to characterize the genomic profiles of adenocarcinomas in the gastroesophageal junction in relation to cancers in the esophagus and the stomach. Profiles of gains/losses as well as gene expression profiles were obtained from 27 gastroesophageal adenocarcinomas by means of 32k high-resolution array-based comparative genomic hybridization and 27k oligo gene expression arrays, and putative target genes were validated in an extended series. Adenocarcinomas in the distal esophagus and the gastroesophageal junction showed strong similarities with the most common gains at 20q13, 8q24, 1q21-23, 5p15, 13q34, and 12q13, whereas different profiles with gains at 5p15, 7p22, 2q35, and 13q34 characterized gastric cancers. CDK6 and EGFR were identified as putative target genes in cancers of the esophagus and the gastroesophageal junction, with upregulation in one quarter of the tumors. Gains/losses and gene expression profiles show strong similarity between cancers in the distal esophagus and the gastroesophageal junction with frequent upregulation of CDK6 and EGFR, whereas gastric cancer displays distinct genetic changes. These data suggest that molecular diagnostics and targeted therapies can be applied to adenocarcinomas of the distal esophagus and gastroesophageal junction alike.

Genome-wide gene copy number and expression analysis of primary gastric tumors and gastric cancer cell lines

Background

Gastric cancer is one of the most common malignancies worldwide and the second most common cause of cancer related death. Gene copy number alterations play an important role in the development of gastric cancer and a change in gene copy number is one of the main mechanisms for a cancer cell to control the expression of potential oncogenes and tumor suppressor genes.

Methods

To highlight genes of potential biological and clinical relevance in gastric cancer, we carried out a systematic array-based survey of gene expression and copy number levels in primary gastric tumors and gastric cancer cell lines and validated the results using an affinity capture based transcript analysis (TRAC assay) and real-time qRT-PCR.

Results

Integrated microarray analysis revealed altogether 256 genes that were located in recurrent regions of gains or losses and had at least a 2-fold copy number- associated change in their gene expression. The expression levels of 13 of these genes, ALPK2, ASAP1, CEACAM5, CYP3A4, ENAH, ERBB2, HHIPL2, LTB4R, MMP9, PERLD1, PNMT, PTPRA, and OSMR, were validated in a total of 118 gastric samples using either the qRT-PCR or TRAC assay. All of these 13 genes were differentially expressed between cancerous samples and nonmalignant tissues (p < 0.05) and the association between copy number and gene expression changes was validated for nine (69.2%) of these genes (p < 0.05).

Conclusion

In conclusion, integrated gene expression and copy number microarray analysis highlighted genes that may be critically important for gastric carcinogenesis. TRAC and qRT-PCR analyses validated the microarray results and therefore the role of these genes as potential biomarkers for gastric cancer.

Early events during neoplastic progression in Barrett's esophagus

Barrett's esophagus is a condition in which the stratified squamous epithelium of the distal esophagus is replaced by specialized intestinal metaplasia. Clinical management of Barrett's esophagus, like many other "premalignant" conditions, is characterized by overdiagnosis of benign early changes that will not cause death or suffering during the lifetime of an individual and underdiagnosis of life-threatening early disease. Recent studies of a number of different types of cancer have revealed much greater genomic complexity than was previously suspected. This genomic complexity could create challenges for early detection and prevention if it develops in premalignant epithelia prior to cancer. Neoplastic progression unfolds in space and time, and Barrett's esophagus provides one of the best models for rapid advances, including "gold standard" cohort studies, to distinguish individuals who do and do not progress to cancer. Specialized intestinal metaplasia has many properties that appear to be protective adaptations to the abnormal environment of gastroesophageal reflux. A large body of evidence accumulated over several decades implicates chromosome instability in neoplastic progression from Barrett's esophagus to esophageal adenocarcinoma. Small, spatial scale studies have been used to infer the temporal order in which genomic abnormalities develop during neoplastic progression in Barrett's esophagus. These spatial studies have provided the basis for prospective cohort studies of biomarkers, including DNA content abnormalities (tetraploidy, aneuploidy) and a biomarker panel of 9p LOH, 17p LOH and DNA content abnormalities. Recent advances in SNP array technology provide a uniform platform to assess chromosome instability.

Differences in the molecular biology of adenocarcinoma of the esophagus, gastric cardia, and upper gastric third

Adenocarcinoma of the distal esophagus, gastric cardia, and upper gastric third are grouped in type I-III by the Siewert classification. This classification is based on the endoscopic localisation of the tumor center, and is the most important diagnostic tool to group these tumors. On a molecular level, there is currently no marker that would allow to differentiate the three different types. Furthermore, the Siewert classification was not uniformly used in the recent literature, making interpretation and generalization of these results difficult. However, several potential targets have been identified that may help to separate these tumors by molecular markers, and are summarized in this chapter.

Chromosomal instability and copy number alterations in Barrett's esophagus and esophageal adenocarcinoma

PURPOSE

Chromosomal instability, as assessed by many techniques, including DNA content aneuploidy, loss of heterozygosity, and comparative genomic hybridization, has consistently been reported to be common in cancer and rare in normal tissues. Recently, a panel of chromosome instability biomarkers, including loss of heterozygosity and DNA content, has been reported to identify patients at high and low risk of progression from Barrett's esophagus (BE) to esophageal adenocarcinoma (EA), but required multiple platforms for implementation. Although chromosomal instability involving amplifications and deletions of chromosome regions have been observed in nearly all cancers, copy number alterations (CNA) in premalignant tissues have not been well characterized or evaluated in cohort studies as biomarkers of cancer risk.

EXPERIMENTAL DESIGN

We examined CNAs in 98 patients having either BE or EA using Bacterial Artificial Chromosome (BAC) array comparative genomic hybridization to characterize CNAs at different stages of progression ranging from early BE to advanced EA.

RESULTS

CNAs were rare in early stages (less than high-grade dysplasia) but were progressively more frequent and larger in later stages (high-grade dysplasia and EA), including high-level amplifications. The number of CNAs correlated highly with DNA content aneuploidy. Patients whose biopsies contained CNAs involving >70 Mbp were at increased risk of progression to DNA content abnormalities or EA (hazards ratio, 4.9; 95% confidence interval, 1.6-14.8; P = 0.0047), and the risk increased as more of the genome was affected.

CONCLUSIONS

Genome-wide analysis of CNAs provides a common platform for the evaluation of chromosome instability for cancer risk assessment as well as for the identification of common regions of alteration that can be further studied for biomarker discovery.

The aurora kinase A regulates GSK-3beta in gastric cancer cells

Aurora kinase A (AURKA) is located at 20q13, a region that is frequently amplified in gastric cancer. In this study, we have investigated the role of AURKA in regulating glycogen synthase kinase (GSK)-3beta and beta-catenin/TCF complex in gastric cancer cells. Our results demonstrate a significant increase in the phosphorylation of GSK-3beta at Ser 9 following the overexpression of AURKA in AGS cells. The immunoprecipitation with antibodies specific for AURKA and GSK-3beta indicated that the two proteins coexist in the same protein complex. The recombinant human AURKA protein phosphorylated the GSK-3beta protein at Ser 9 in a concentration-dependent manner, in vitro. The phosphorylation of beta-catenin (Ser33/37/Thr41) by GSK-3beta is known to target beta-catenin towards degradation. In line with our findings, the increase in phospho-GSK-3beta level was accompanied by a significant decrease in beta-catenin phosphorylation (Ser33/37/Thr41) and accumulation of beta-catenin protein. The knockdown of AURKA reversed the phosphorylation of GSK-3beta and the beta-catenin protein levels. The immunofluorescence analysis demonstrated colocalization of AURKA and GSK-3beta proteins and a significant increase in the nuclear beta-catenin levels in cells overexpressing AURKA. The beta-catenin/TCF transcription activity was measured using the pTopFlash and its mutant pFopFlash luciferase reporter vectors. Indeed, AURKA overexpression led to a significant increase in the pTopFlash reporter activity, whereas kinase dead AURKA mutant (D274A) had no effect. Consistent with these findings, we detected a significant mRNA up-regulation of several direct targets of the beta-catenin/TCF transcription complex (cyclin D1, c-MYC, c-MYC-binding protein, CLDN1, FGF18 and vascular endothelial growth factor), and a two-fold increase in the proliferation rate in AURKA overexpressing cells. We conclude that the AURKA/GSK-3beta interaction is important in regulating beta-catenin, underscoring a novel oncogenic potential for AURKA in gastric tumorigenesis.

Single nucleotide polymorphism-based genome-wide chromosome copy change, loss of heterozygosity, and aneuploidy in Barrett's esophagus neoplastic progression

Chromosome copy gain, loss, and loss of heterozygosity (LOH) involving most chromosomes have been reported in many cancers; however, less is known about chromosome instability in premalignant conditions. 17p LOH and DNA content abnormalities have been previously reported to predict progression from Barrett's esophagus (BE) to esophageal adenocarcinoma (EA). Here, we evaluated genome-wide chromosomal instability in multiple stages of BE and EA in whole biopsies. Forty-two patients were selected to represent different stages of progression from BE to EA. Whole BE or EA biopsies were minced, and aliquots were processed for flow cytometry and genotyped with a paired constitutive control for each patient using 33,423 single nucleotide polymorphisms (SNP). Copy gains, losses, and LOH increased in frequency and size between early- and late-stage BE (P < 0.001), with SNP abnormalities increasing from <2% to >30% in early and late stages, respectively. A set of statistically significant events was unique to either early or late, or both, stages, including previously reported and novel abnormalities. The total number of SNP alterations was highly correlated with DNA content aneuploidy and was sensitive and specific to identify patients with concurrent EA (empirical receiver operating characteristic area under the curve = 0.91). With the exception of 9p LOH, most copy gains, losses, and LOH detected in early stages of BE were smaller than those detected in later stages, and few chromosomal events were common in all stages of progression. Measures of chromosomal instability can be quantified in whole biopsies using SNP-based genotyping and have potential to be an integrated platform for cancer risk stratification in BE.

Esophageal adenocarcinoma arising from Barrett's epithelium in Taiwan

The prevalence of Barrett's esophagus (BE) in Eastern countries is rising to match the prevalence in the West. However, a corresponding trend of BE-associated adenocarcinoma has yet to be observed in Asia. Historically, adenocarcinoma complicating BE has been considered a rare event in Taiwan. In the present report, we collected three Taiwanese cases of esophageal adenocarcinoma arising from BE. The first case was a 37-year-old man with an advanced cancer that developed on pre-existing BE after a 3-year interval without endoscopic surveillance. The second case was a 63-year-old man who presented with odynophagia and was found to have an ulcerative tumor centered on the characteristic Barrett's mucosa. The final case was a 44-year-old man who presented with gradual-onset dysphagia and weight loss, without typical reflux symptom. Our report emphasizes the need for an updated epidemiologic study to determine the incidence of BE-associated adenocarcinoma in Taiwan.

Transcriptional oncogenomic hot spots in Barrett's adenocarcinomas: serial analysis of gene expression

Serial analysis of gene expression (SAGE) provides quantitative and comprehensive expression profiling in a given cell population. In our efforts to define gene expression alterations in Barrett's-related adenocarcinomas (BA), we produced eight SAGE libraries and obtained a total of 457,894 expressed tags with 32,035 (6.9%) accounting for singleton tags. The tumor samples produced an average of 71,804 tags per library, whereas normal samples produced an average of 42,669 tags per library. Our libraries contained 67,200 unique tags representing 16,040 known gene symbols. Five hundred and sixty-eight unique tags were differentially expressed between BAs and normal tissue samples (at least twofold; P<or=0.05), 395 of these matched to known genes. Interestingly, the distribution of altered genes was not uniform across the human genome. Overexpressed genes tended to cluster in well-defined hot spots located in certain chromosomes. For example, chromosome 19 had 26 overexpressed genes, of which 18 mapped to 19q13. Using the gene ontology approach for functional classification of genes, we identified several groups that are relevant to carcinogenesis. We validated the SAGE results of five representative genes (ANPEP, ECGF1, PP1201, EIF5A1, and GKN1) using quantitative real-time reverse-transcription PCR on 31 BA samples and 26 normal samples. In addition, we performed an immunohistochemistry analysis for ANPEP, which demonstrated overexpression of ANPEP in 6/7 (86%) Barrett's dysplasias and 35/65 (54%) BAs. ANPEP is a secreted protein that may have diagnostic and/or prognostic significance for Barrett's progression. The use of genomic approaches in this study provided useful information about the molecular pathobiology of BAs.

Rodent endosonography to monitor esophageal cancer

Animal models of luminal cancers are important to understand and assess chemopreventive and chemotherapeutic interventions. However, the ability to assess tumor growth and response without animal sacrifice is limited. We assessed the ability of luminal sonography to assess the presence of tumor and its size in a surgical esophagojejunostomy model of esophageal cancer. Luminal sonography had a sensitivity of 88%, specificity of 100%, and accuracy of 93% in identifying the esophageal cancers. The tumor dimensions on luminal sonography were within 11% of autopsy measurements. Minimal tumor dimension was 2 mm and maximum 6.2 mm. The procedure was feasible without technical difficulty. In conclusion, rodent endosonography is a useful technique that can accurately determine the presence of tumors as well as their dimensions.

Identification of overexpressed genes in hepatocellular carcinoma, with special reference toubiquitin-conjugating enzyme E2Cgene expression

This study consisted of 2 aims: (i) to determine genes associated with hepatocellular carcinoma (HCC) by microarray analysis; and (ii) to evaluate the clinicopathological significance of human ubiquitin-conjugating enzyme E2C (Ube2c) found to be overexpressed in HCC from microarray analysis. Laser microdissection and cDNA-microarray were performed to identify genes associated with HCC. We then focused on the Ube2c gene. Using real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR), Ube2c expression status and clinicopathological significance were studied in 65 clinical HCC samples. A number of genes upregulated in HCC cells compared to noncancerous liver cells were identified, one of which was the Ube2c gene. Ube2c gene expression in the cancer tissue was higher than in the corresponding noncancerous tissue in 62 of the 65 cases (95.4%, p < 0.01). Tumors with high Ube2c expression showed higher frequencies of tumor invasion to capsular formation (fc-inf), invasion to portal vein (vp) and tumor de-differentiation (p < 0.05). Patients with high Ube2c expression also showed significantly worse disease-free survival rates than those with low Ube2c expression (p < 0.01). In addition, Ube2c expression was found to be an independent prognostic factor for disease-free survival rate in multivariate analysis. We identified differentially expressed genes between HCC and normal liver tissues. Of those, the Ube2c gene appeared to be associated with HCC progression, and may be useful as a prognostic indicator for HCC patients.

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.

Expression of calcium-binding proteins S100A2 and S100A4 in Barrett's adenocarcinomas

In this study, we investigated the mRNA and protein expression of S100A2 and S100A4 in adenocarcinomas of the stomach and esophagus. Real-time reverse transcription-polymerase reaction analysis on 72 tumors revealed frequent overexpression of S100A2 and S100A4 in Barrett's adenocarcinomas (BAs) (P < .01). Immunohistochemical analysis on tumor tissue microarrays that contained 187 tumors showed absent to weak staining for S100A2 in all normal gastric mucosa samples, whereas normal esophageal mucosa samples demonstrated moderate to strong nuclear staining. Contrary to the nuclear expression of S100A2 in normal esophageal mucosa, two thirds of Barrett's dysplasia and BAs that overexpressed S100A2 demonstrated stronger cytosolic staining than nuclear staining (P < .001). Overexpression of S100A2 protein was more frequently seen in well-differentiated tumors than in others (P = .02). Moderate to strong staining of S100A4 was detected in two thirds of tumors and was frequently observed in the presence of Barrett's esophagus (P = .02). Similar to S100A2, the expression of S100A4 was predominantly cytosolic in two thirds of the tumors (P = .001). There was a significant correlation between S100A4 overexpression and lymph node metastasis (N(2)-N(4)) (P = .027). These results demonstrate frequent cytosolic overexpression of S100A2 and S100A4 in BAs. Further studies are ongoing to understand the biological significance of these S100A proteins in Barrett's tumorigenesis.

Molecular dissection of 17q12 amplicon in upper gastrointestinal adenocarcinomas

DNA amplification at 17q is frequently detected in upper gastrointestinal adenocarcinomas (UGC; stomach and esophagus). In this study, we did fluorescence in situ hybridization on a tissue microarray that contained 304 UGCs and 89 normal stomach samples using a approximately 168-kb BAC clone (CTD-2019C10) that maps to 17q12-q21.1. This 168-kb region contains the following genes: PPP1R1B/DARPP-32, STARD3, TCAP, PNMT, PERLD1, ERBB2, C17orf37, and GRB7 as well as the first two exons of ZNFN1A3. DNA amplification (> or =5 signals) was detected in 85 of 282 (30%) of UGCs, and high-level amplification (> or =10 signals) was seen in 28 of 282 (10%) of all tumors. Adenocarcinomas of gastroesophageal junction and lower esophagus had the highest frequency of amplification (45%) compared with stomach tumors (27%; P = 0.04). On the other hand, 38% of tumors with intestinal-type morphology had amplification compared with 26% of diffuse-type tumors (P = 0.02). We further did quantitative real-time reverse transcription-PCR on 74 frozen tissue samples from UGCs for 11 genes located within or adjacent to the boundaries of this approximately 168-kb genomic region. These genes include all 9 genes that are fully or partially located inside the CTD-2019C10 clone as well as 2 additional adjacent genes (NEUROD and TOP2A). Overexpression of PPP1R1B/DARPP-32, TCAP, and TOP2A was seen in approximately half of the tumors, whereas STARD3 and ZNFN1A3 were rarely overexpressed (12%). Interestingly, there was a statistical correlation between expression of all 8 genes that map between PPP1R1B/DARPP-32 and GRB7, whereas expression of NEUROD, ZNFN1A3, and TOP2A that are partially inside or adjacent to the boundaries of the CTD-2019C10 clone did not correlate with the expression of any of these 8 genes. These data show a transcriptionally active oncogenomic region bounded by PPP1R1B/DARPP-32 and GRB7 in UGCs and provide further insight into expression levels of several critical genes.

Pathogenesis and classification of cancer around the gastroesophageal junction--not so different in Japan

Japanese patients with early adenocarcinoma of the esophagus have well-preserved gastric acid secretion, consistent with other parts of the world, reinforcing the likely importance of the luminal environment for pathogenesis. Progress in researching carcinomas that occur around the gastroesophageal junction would be facilitated by consensus-based review of the inadequate approaches currently used for classification of these tumors with subsequent development and widespread adoption of improved criteria.

Overexpression of CEBPbeta correlates with decreased TFF1 in gastric cancer

CCAAT element binding protein beta (C/EBPbeta) is an important regulator of cell growth, differentiation and in promoting tumor invasiveness. C/EBPbeta is located on chromosome 20q, which is amplified in many solid tumors including gastric cancers (GC). We sought to characterize the status of C/EBPbeta expression in GCs, which was recently found to repres TFF1 gene. Microarray analysis revealed overexpression of C/EBPbeta in 25 of 27 (93%) GC when compared to 12 normal gastric tissue samples. RT-PCR analysis confirmed the overexpression of C/EBPbeta transcripts in 54 of 59 (91%) GC. In total, 15 of 18 gastric tumors exhibited at least fivefold higher C/EBPbeta transcript levels compared to their corresponding adjacent normal gastric tissue samples. Moreover, immunohistochemistry analysis demonstrated increased nuclear staining of C/EBPbeta in 10 of 13 GC and at least fourfold overexpression of C/EBPbeta in three primary GC compared to adjacent normal gastric tissue. Furthermore, a striking correlation of decreased TFF1 expression with increased C/EBPbeta was observed in the gastric tumors studied. Microarray analysis demonstrated a loss of TFF1 expression in all 27 GC cases examined, of which 25 exhibited high C/EBPbeta expression compared to normal gastric tissue. RT-PCR analysis revealed loss of TFF1 expression in 56 of 59 gastric tumors in which 54 of these tumors exhibited overexpression of C/EBPbeta. Immunohistochemical analysis revealed overexpression of C/EBPbeta in 10 of 13 gastric tumors that exhibited low expression of TFF1 at the protein level. Thus, overexpression of the transcription factor C/EBPbeta in the majority of GCs is a novel finding.

Expression of tight-junction protein claudin-7 is an early event in gastric tumorigenesis

Trefoil factor-1 (Tff1) expression is remarkably down-regulated in nearly all human gastric cancers. Therefore, we used the Tff1 knockout mouse model to detect molecular changes in preneoplastic gastric dysplasia. Oligonucleotide microarray gene expression analysis of gastric dysplasia of Tff1-/- mice was compared to that of normal gastric mucosa of wild-type mice. The genes most overexpressed in Tff1-/- mice included claudin-7 (CLDN7), early growth response-1 (EGR1), and epithelial membrane protein-1 (EMP1). Quantitative real-time reverse transcriptase-polymerase chain reaction and immunohistochemistry showed that Cldn7 was overexpressed in all 10 Tff1-/- gastric dysplasia samples. Comparison with our serial analysis of gene expression database of human gastric cancer revealed similar deregulation in human gastric cancers. Quantitative real-time reverse transcriptase-polymerase chain reaction of human gastric adenocarcinoma samples indicated that, of these three genes, CLDN7 was the most frequently up-regulated gene. Using immunohistochemistry, both mouse and human gastric glands overexpressed Cldn7 in dysplastic but not surrounding normal glands. Cldn7 expression was observed in 30% of metaplasia, 80% of dysplasia, and 70% of gastric adenocarcinomas. Interestingly, 82% of human intestinal-type gastric adenocarcinomas expressed Cldn7 whereas diffuse-type gastric adenocarcinomas did not (P < 0.001). These results suggest that Cldn7 expression is an early event in gastric tumorigenesis that is maintained throughout tumor progression.

UbcH10 overexpression may represent a marker of anaplastic thyroid carcinomas

The hybridisation of an Affymetrix HG_U95Av2 oligonucleotide array with RNAs extracted from six human thyroid carcinoma cell lines and a normal human thyroid primary cell culture led us to the identification of the UbcH10 gene that was upregulated by 150-fold in all of the carcinoma cell lines in comparison to the primary culture cells of human normal thyroid origin. Immunohistochemical studies performed on paraffin-embedded tissue sections showed abundant UbcH10 levels in thyroid anaplastic carcinoma samples, whereas no detectable UbcH10 expression was observed in normal thyroid tissues, in adenomas and goiters. Papillary and follicular carcinomas were only weakly positive. These results were further confirmed by RT-PCR and Western blot analyses. The block of UbcH10 protein synthesis induced by RNA interference significantly reduced the growth rate of thyroid carcinoma cell lines. Taken together, these results would indicate that UbcH10 overexpression is involved in thyroid cell proliferation, and may represent a marker of thyroid anaplastic carcinomas.

Molecular biology of esophageal cancer in the genomics era

The incidence of esophageal adenocarcinoma is rising in the United States and Western countries. Significant differences exist between esophageal adenocarcinoma and squamous cell carcinoma in the molecular mechanisms responsible for the tumorigenesis process. State-of-the-art techniques such as gene microarrays and proteomics will greatly aid in the development of new therapies targeting specific molecular pathways,ultimately leading to improved survival in patients who have esophageal cancer.

Transcriptional repression of TFF1 in gastric epithelial cells by CCAAT/enhancer binding protein-beta

TFF1 is a member of a unique family of gastrointestinal peptides. Loss of TFF1 expression has been observed in the majority of human gastric cancers and the biological significance of this loss has been demonstrated in a Tff1 knockout mouse model. However, few TFF1 gene mutations or allelic loss have also been documented. To understand the molecular mechanism repressing the TFF1 gene expression, the 5'-flanking region of the human TFF1 gene was characterized. We found a repressor region (-241 to -84), which is active in MKN45 and IMGE5 cells expressing endogenous TFF1 gene. A consensus binding site for C/EBPbeta was identified and EMSA analysis demonstrated specific binding of CEBPbeta. Mutation of this C/EBPbeta element potentiated the transactivation of TFF1 by 50% and 145% for MKN45 and IMGE5 cells respectively. Furthermore, co-transfection of C/EBPbeta isoforms specifically decreased TFF1 promoter activity. These findings suggest that C/EBPbeta is involved in the down-regulating of TFF1 gene expression and this mode of repression may account at least in part for the loss of TFF1 gene expression in transformed human and mice gastric epithelial cells.

Differential Response to Preoperative Chemoradiation and Surgery in Esophageal Adenocarcinomas Based on Presence of Barrett's Esophagus and Symptomatic Gastroesophageal Reflux

BACKGROUND

Barrett's esophagus and gastroesophageal reflux disease (GERD) are recognized to predispose to esophageal adenocarcinoma. Abdel-Latif and colleagues recently suggested that esophageal adenocarcinoma patients with GERD might be resistant to multimodality treatment. In this study, we investigated potential differences in clinical outcomes in esophageal adenocarcinoma patients based on the presence of identifiable Barrett's mucosa and/or history of symptomatic GERD.

METHODS

Eighty-four patients with resectable esophageal adenocarcinoma, who completed the planned preoperative chemoradiation and underwent a potentially curative esophageal resection were retrospectively evaluated. Postoperative survival was compared between patients with or without underlying Barrett's esophagus and history of symptomatic GERD. Patients with pathologic complete response (path CR) and those with partial or no response (path PR) were compared to determine if presence of Barrett's esophagus and history of symptomatic GERD influence the path CR rates.

RESULTS

We found significantly lower postoperative survival in patients with Barrett's associated adenocarcinoma (vs adenocarcinoma arising de novo, p = 0.031) and patients with symptomatic GERD (vs patients without symptomatic GERD, p = 0.019). Furthermore, the subset of patients with path PR (vs path CR) after chemoradiation have a significantly higher proportion of patients with Barrett's esophagus (HR = 4.38, confidence interval [CI] = 1.39 to 13.83, p = 0.012) and patients with GERD (HR = 2.71, CI = 1.13 to 6.50, p = 0.026).

CONCLUSIONS

Patients with esophageal adenocarcinoma may have differences in response to preoperative chemoradiation based on the presence of Barrett's esophagus and history of symptomatic GERD.

Aurora B overexpression associates with the thyroid carcinoma undifferentiated phenotype and is required for thyroid carcinoma cell proliferation

Alterations in chromosome number (aneuploidy) are common in human neoplasias. Loss of mitotic regulation is believed to induce aneuploidy in cancer cells and act as a driving force during the malignant progression. The serine/theronine protein kinases of aurora family genes play a critical role in the regulation of key cell cycle processes. Aurora B mediates chromosome segregation by ensuring orientation of sister chromatids and overexpression of Aurora B in diploid human cells NHDF (normal human diploid fibroblast) induces multinuclearity. We analyzed Aurora B expression in human thyroid carcinomas. Cell lines originating from different histotypes showed an increase in Aurora B expression. Immunohistochemical analysis of archive samples showed a high expression of Aurora B in anaplastic thyroid carcinomas; conversely, Aurora B expression was not detectable in normal thyroid tissue. Real-time PCR analysis confirmed a strong expression of Aurora B in anaplastic thyroid carcinomas. The block of Aurora B expression induced by RNA interference or by using an inhibitor of Aurora kinase activity significantly reduced the growth of thyroid anaplastic carcinoma cells.

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.

Overexpression, genomic amplification and therapeutic potential of inhibiting the UbcH10 ubiquitin conjugase in human carcinomas of diverse anatomic origin

Gene expression profiling of anatomically diverse carcinomas and their corresponding normal tissues was used to identify genes with cancer-associated expression. We show here that the ubiquitin conjugase, UbcH10, is significantly overexpressed in many different types of cancers and is associated with the degree of tumor differentiation in carcinomas of the breast, lung, ovary and bladder, as well as in glioblastomas. We also show that UbcH10 overexpression in gastro-esophageal, and probably other carcinomas may be a direct consequence of chromosomal amplification at the UbcH10 locus, 20q13.1, a region known to be amplified in diverse tumors. To evaluate whether inhibition of UbcH10 function may be therapeutically relevant in cancer, we used small interfering RNAs (siRNAs) to silence UbcH10 transcription selectively. Diminution of UbcH10 expression significantly inhibited both tumor and normal cell proliferation without inducing cell death. However, when combined with agonists of the DR5/TRAIL receptor, siRNAs directed against the UbcH10 transcript dramatically enhanced killing of cancer cells, but not of proliferating primary human epithelial cells or fibroblasts. Together, these data demonstrate that UbcH10 plays an important role in tumor development and that its inhibition in combination with agonists of the TRAIL receptor may provide an enhanced therapeutic index.

Hypermethylation of tumor suppressor genes (p16INK4A, p14ARF and APC) in adenocarcinomas of the upper gastrointestinal tract

Aberrant promoter methylation is an important mechanism for gene silencing. In the present study, 50 Barrett's esophagus-associated esophageal adenocarcinomas (ADC), 50 cardiac ADC and 50 gastric ADC were investigated by means of methylation-specific real-time PCR for hypermethylation in the tumor suppressor genes APC, p16(INk4A) and p14(ARF). Additionally, expression of p16(INK4A) protein in the carcinomas was assessed using immunohistochemistry. Marked differences in hypermethylation were found between esophageal, cardiac and gastric ADC in the APC gene (78% vs. 32% vs. 84%) and in the p16(INK4A) gene (54% vs. 36% vs. 10%). Hypermethylation of p14(ARF) was absent from esophageal ADC and present infrequently in cardiac (2%) and gastric ADC (10%). Complete loss of p16(INK4A) protein expression was detectable in 45% of all tumors and was significantly associated with hypermethylation of the p16(INK4A) gene (p<0.0001, chi(2)-test). Our results suggest that hypermethylation of p16(INK4A) and APC are frequent findings in esophageal, cardiac and gastric ADC. Additionally, the data point to a tumor specific methylation pattern in upper gastrointestinal ADC.

Molecular biology of sporadic gastric cancer: prognostic indicators and novel therapeutic approaches

Both the availability of multiple treatment modalities and novel therapeutic targets make the correct prognostic stratification and the identification of truly predictive factors an issue of major debate in gastric cancer. Along with "classic" prognostic factors such as those related to the diffusion of the tumour at diagnosis (i.e., depth of gastric wall infiltration, locoregional lymph nodes or distant metastases) or those concerning the pathologic characteristics of the tumour, other, innovative, factors should be considered if a better definition of the characteristics of the tumour is to be given. These biological factors are often derived from the genetic process, which is thought to represent a crucial step to gastric cancer (DNA copy number changes, microsatellite instability, thymidilate synthase, E-cadherin, beta-catenin, mucin antigen, p53, c-erb B-2, COX-2, matrix metalloproteinases, VEGFR and EGFR). Some of those putative prognostic indicators can also be considered predictive of response to therapy as they are a molecular target either to chemotherapeutics (i.e., thymidilate synthase that is targeted by 5FU) or to a new class of antineoplastic molecules (i.e., c-erb B-2 targeted by trastuzumab, COX-2 by NSAIDs, matrix metalloproteinases, EGFR and VEGFR by specific inhibitors).

Chromosomal gains and genomic loss of p53 and p16 genes in Barrett's esophagus detected by fluorescence in situ hybridization of cytology specimens

Endoscopic brush cytology is a promising surveillance technique for Barrett's esophagus. Ancillary markers are sought to increase the sensitivity of cytology and allow identification of patients at increased risk for disease progression. To determine if there are specific genetic changes in Barrett's esophagus with associated high-grade dysplasia/intramucosal adenocarcinoma compared to those without dysplasia, we performed fluorescence in situ hybridization (FISH) on cytologic specimens using probes to chromosomes and genomic regions previously described as altered in this disease. We studied archival brush cytology slides from 40 Barrett's esophagus patients: 21 with biopsy-proven high-grade dysplasia/carcinoma and 19 with no dysplasia and a minimum 5 years of negative follow-up. Centromeric enumeration probes (CEP) for chromosomes 6, 7, 11, and 12, and locus-specific probes (LSI) for 9p21 (p16 gene), and 17p13.1 (p53 gene) loci along with their corresponding CEP (9 and 17, respectively) were used in this study. A positive FISH result was defined as the presence of cells with >2 CEP signals or with a loss of the LSI signals relative to their corresponding CEP. p53 locus loss and/or aneusomy of chromosomes 6, 7, 11, and 12 abnormalities could be detected by FISH in routinely processed endoscopic brush cytology specimens from 95% of biopsy-positive cases with a specificity of 100%. Interestingly, all five cases with cytologic changes classified as indefinite for dysplasia from patients with a positive biopsy showed changes by FISH. Loss of the p16 locus was seen commonly in patients both with and without dysplasia/carcinoma. Selected biomarkers from this study merit further investigation to determine their potential to detect genetic changes in patients with Barrett's esophagus prior to the development of high-grade dysplasia.