K-ras codon 12 mutations in Barrett's oesophagus and adenocarcinomas of the oesophagus and oesophagogastric junction

PD-1 blockade enhances chemotherapy toxicity in oesophageal adenocarcinoma

Chemotherapy upregulates immune checkpoint (IC) expression on the surface of tumour cells and IC-intrinsic signalling confers a survival advantage against chemotherapy in several cancer-types including oesophageal adenocarcinoma (OAC). However, the signalling pathways mediating chemotherapy-induced IC upregulation and the mechanisms employed by ICs to protect OAC cells against chemotherapy remain unknown. Longitudinal profiling revealed that FLOT-induced IC upregulation on OE33 OAC cells was sustained for up to 3 weeks post-treatment, returning to baseline upon complete tumour cell recovery. Pro-survival MEK signalling mediated FLOT-induced upregulation of PD-L1, TIM-3, LAG-3 and A2aR on OAC cells promoting a more immune-resistant phenotype. Single agent PD-1, PD-L1 and A2aR blockade decreased OAC cell viability, proliferation and mediated apoptosis. Mechanistic insights demonstrated that blockade of the PD-1 axis decreased stem-like marker ALDH and expression of DNA repair genes. Importantly, combining single agent PD-1, PD-L1 and A2aR blockade with FLOT enhanced cytotoxicity in OAC cells. These findings reveal novel mechanistic insights into the immune-independent functions of IC-intrinsic signalling in OAC cells with important clinical implications for boosting the efficacy of the first-line FLOT chemotherapy regimen in OAC in combination with ICB, to not only boost anti-tumour immunity but also to suppress IC-mediated promotion of key hallmarks of cancer that drive tumour progression.

From genetics to signaling pathways: molecular pathogenesis of esophageal adenocarcinoma

Esophageal adenocarcinoma (EAC) has one of the fastest rising incidence rates in the U.S. and many other Western countries. One of the unique risk factors for EAC is gastroesophageal reflux disease (GERD), a chronic digestive condition in which acidic contents from the stomach, frequently mixed with duodenal bile, enter the esophagus resulting in esophageal tissue injury. At the cellular level, progression to EAC is underlined by continuous DNA damage caused by reflux and chronic inflammatory factors that increase the mutation rate and promote genomic instability. Despite recent successes in cancer diagnostics and treatment, EAC remains a poorly treatable disease. Recent research has shed new light on molecular alterations underlying progression to EAC and revealed novel treatment options. This review focuses on the genetic and molecular studies of EAC. The molecular changes that occur during the transformation of normal Barrett's esophagus to esophageal adenocarcinoma are also discussed.

Regulation of RhoB Gene Expression during Tumorigenesis and Aging Process and Its Potential Applications in These Processes

RhoB, a member of the Ras homolog gene family and GTPase, regulates intracellular signaling pathways by interfacing with epidermal growth factor receptor (EGFR), Ras, and phosphatidylinositol 3-kinase (PI3K)/Akt to modulate responses in cellular structure and function. Notably, the EGFR, Ras, and PI3K/Akt pathways can lead to downregulation of RhoB, while simultaneously being associated with an increased propensity for tumorigenesis. Functionally, RhoB, part of the Rho GTPase family, regulates intracellular signaling pathways by interfacing with EGFR, RAS, and PI3K/Akt/mammalian target of rapamycin (mTOR), and MYC pathways to modulate responses in cellular structure and function. Notably, the EGFR, Ras, and PI3K/Akt pathways can lead to downregulation of RhoB, while simultaneously being associated with an increased propensity for tumorigenesis. RHOB expression has a complex regulatory backdrop consisting of multiple histone deacetyltransferase (HDACs 1 and 6) and microRNA (miR-19a, -21, and -223)-mediated mechanisms of modifying expression. The interwoven nature of RhoB’s regulatory impact and cellular roles in regulating intracellular vesicle trafficking, cell motion, and the cell cycle lays the foundation for analyzing the link between loss of RhoB and tumorigenesis within the context of age-related decline in RhoB. RhoB appears to play a tissue-specific role in tumorigenesis, as such, uncovering and appreciating the potential for restoration of RHOB expression as a mechanism for cancer prevention or therapeutics serves as a practical application. An in-depth assessment of RhoB will serve as a springboard for investigating and characterizing this key component of numerous intracellular messaging and regulatory pathways that may hold the connection between aging and tumorigenesis.

HPV, KRAS mutations, alcohol consumption and tobacco smoking effects on esophageal squamous-cell carcinoma carcinogenesis

Esophageal squamous-cell carcinoma (ESCC) is an invasive neoplastic disease generally associated with poor survival rates. The incidence of ESCC is characterized by marked geographic variation, with highest rates noted in developing Southeastern African, Central and Eastern Asian countries. In the developed Western European and North American regions where there is a low disease incidence, heavy alcohol and cigarette consumption constitute major risk factors. The toxic effects of both these risk factors cause chronic irritation and inflammation of the esophageal mucosa, while at the cellular level they further confer mutagenic effects by the activation of oncogenes (e.g., RAS mutations), inhibition of tumor-suppressor genes, and profound DNA damage. Viral infections, particularly with human papillomavirus, may activate specific antiapoptotic, proliferative and malignant cellular responses that may be intensified in combination with the effects of alcohol and tobacco. In countries with a high ESCC incidence, low socioeconomic status and an inadequate diet of poorly preserved food are combined with basic nutritional deficiencies and inadequate medical treatment. These conditions are favorable to the above-mentioned risk factors implicated in ESCC development, which may be present and/or habitually used in certain populations. New perspectives in epidemiological studies of ESCC development and its risk factors allow genome-wide research involving specific environments and habits. Such research should consist of adequately large and representative samples, should use newly designed informative genetic markers, and apply genomic variation analysis of the functional transcripts involved in malignant cell cycle regulation and neoplastic transformation in the multi-step process of ESCC carcinogenesis.

Barrett's Esophagus: A Comprehensive and Contemporary Review for Pathologists

This review provides a summary of our current understanding of, and the controversies surrounding, the diagnosis, pathogenesis, histopathology, and molecular biology of Barrett's esophagus (BE) and associated neoplasia. BE is defined as columnar metaplasia of the esophagus. There is worldwide controversy regarding the diagnostic criteria of BE, mainly with regard to the requirement to histologically identify goblet cells in biopsies. Patients with BE are at increased risk for adenocarcinoma, which develops in a metaplasia-dysplasia-carcinoma sequence. Surveillance of patients with BE relies heavily on the presence and grade of dysplasia. However, there are significant pathologic limitations and diagnostic variability in evaluating dysplasia, particularly with regard to the more recently recognized unconventional variants. Identification of non-morphology-based biomarkers may help risk stratification of BE patients, and this is a subject of ongoing research. Because of recent achievements in endoscopic therapy, there has been a major shift in the treatment of BE patients with dysplasia or intramucosal cancer away from esophagectomy and toward endoscopic mucosal resection and ablation. The pathologic issues related to treatment and its complications are also discussed in this review article.

Modeling human gastrointestinal inflammatory diseases using microphysiological culture systems

Gastrointestinal illnesses are a significant health burden for the US population, with 40 million office visits each year for gastrointestinal complaints and nearly 250,000 deaths. Acute and chronic inflammations are a common element of many gastrointestinal diseases. Inflammatory processes may be initiated by a chemical injury (acid reflux in the esophagus), an infectious agent (Helicobacter pylori infection in the stomach), autoimmune processes (graft versus host disease after bone marrow transplantation), or idiopathic (as in the case of inflammatory bowel diseases). Inflammation in these settings can contribute to acute complaints (pain, bleeding, obstruction, and diarrhea) as well as chronic sequelae including strictures and cancer. Research into the pathophysiology of these conditions has been limited by the availability of primary human tissues or appropriate animal models that attempt to physiologically model the human disease. With the many recent advances in tissue engineering and primary human cell culture systems, it is conceivable that these approaches can be adapted to develop novel human ex vivo systems that incorporate many human cell types to recapitulate in vivo growth and differentiation in inflammatory microphysiological environments. Such an advance in technology would improve our understanding of human disease progression and enhance our ability to test for disease prevention strategies and novel therapeutics. We will review current models for the inflammatory and immunological aspects of Barrett's esophagus, acute graft versus host disease, and inflammatory bowel disease and explore recent advances in culture methodologies that make these novel microphysiological research systems possible.

High-incidence of PTEN mutations in Chinese patients with primary small cell carcinoma of the esophagus

Background

Primary small cell carcinoma of the esophagus (PSCCE) is a rare and aggressive tumor with poor prognosis. The aim of this study was to investigate the existence of EGFR, KRAS, PIK3CA and PTEN mutations in PSCCE.

Methods

Clinical–pathological data and paraffin-embedded specimens were collected from 38 patients. Exons 18 to 21 of EGFR, KRAS and PIK3CA status were analyzed by real-time PCR based on ARMS and Scorpion technology in all patients, and the PTEN gene was also screened using real-time PCR and high-resolution melting curve analysis (HRMA).

Results

Only 1 (2.63%) out of 38 patients had EGFR mutations in L858R missense, and KRAS and PIK3CA were not found in the mutational spot in all patients. However, PTEN mutations presented in 14 (36.84%) out of 38 patients, including exon 5 coding for PTEN missense mutation (n =4, 10.53%), exon 6 (n =7, 18.42%), concurrent exon 5 and exon 6 (n =2, 5.26%), and exon 8 (n =1, 2.63%). Concurrent mutations of these genes were not detected in all samples. No statistically significant associations were found between the clinicopathological features and the mutation status of PTEN.

Conclusions

The incidence of PTEN mutations in Chinese patients with PSCCE was higher than that of previous reports in other histological subtypes of esophageal cancer.

Characterization of a novel tumorigenic esophageal adenocarcinoma cell line: OANC1

BACKGROUND

Esophageal adenocarcinoma (EAC) has a very high case fatality rate and is one of the fastest rising cancers worldwide. At the same time, research into EAC has been hampered by a relative lack of pre-clinical models, including representative cell lines.

AIM

The purpose of this study was to establish and characterize a new EAC cell line.

METHODS

Tumor cells were isolated from EAC tissue by enzymatic digestion. Origin of the cell line was confirmed by microsatellite based genotyping. A panel of cancer-related genes was screened for mutations by targeted deep sequencing, Sanger sequencing and high resolution melting.CDKN2A promoter methylation was assessed by methylation specific high resolution melting. HER2 amplification was assessed by fluorescent in situ hybridization. Immunohistochemistry was used to assess expression of markers in xenografts grown in SCID mice.

RESULTS

A novel EAC cell line, OANC1, was derived from a Barrett's-associated EAC. Microsatellite-based genotyping of OANC1 and patient DNA confirmed the origin of the cell line. Sequencing of OANC1 DNA identified homozygous TP53 missense (c.856G[A, p.E286K)and SMAD4 nonsense (c.1333C[T, p.R445X) mutations.OANC1 are tumorigenic when injected sub-cutaneously into SCID mice and xenografts were positive for columnar, glandular and intestinal epithelial markers commonly expressed in EAC. Xenografts exhibited strong p53 expression, consistent with a TP53 mutation. Some proteins, including p16, EGFR and b-catenin, had heterogeneous expression patterns across xenograft cross-sections, indicative of tumor heterogeneity.

CONCLUSIONS

OANC1 represents a valuable addition to the limited range of pre-clinical models for EAC. This new cell line will be a useful model system for researchers studying both basic and translational aspects of this disease.

HDM2 regulation by AURKA promotes cell survival in gastric cancer

PURPOSE

Suppression of P53 (tumor protein 53) transcriptional function mediates poor therapeutic response in patients with cancer. Aurora kinase A (AURKA) and human double minute 2 (HDM2) are negative regulators of P53. Herein, we examined the role of AURKA in regulating HDM2 and its subsequent effects on P53 apoptotic function in gastric cancer.

EXPERIMENTAL DESIGN

Primary tumors and in vitro gastric cancer cell models with overexpression or knockdown of AURKA were used. The role of AURKA in regulating HDM2 and cell survival coupled with P53 expression and activity were investigated.

RESULTS

Overexpression of AURKA enhanced the HDM2 protein level; conversely, knockdown of endogenous AURKA decreased expression of HDM2 in AGS and SNU-1 cells. Dual co-immunoprecipitation assay data indicated that AURKA was associated with HDM2 in a protein complex. The in vitro kinase assay using recombinant AURKA and HDM2 proteins followed by co-immunoprecipitation revealed that AURKA directly interacts and phosphorylates HDM2 protein in vitro. The activation of HDM2 by AURKA led to induction of P53 ubiquitination and attenuation of cisplatin-induced activation of P53 in gastric cancer cells. Inhibition of AURKA using an investigational small-molecule specific inhibitor, alisertib, decreased the HDM2 protein level and induced P53 transcriptional activity. These effects markedly decreased cell survival in vitro and xenograft tumor growth in vivo. Notably, analysis of immunohistochemistry on tissue microarrays revealed significant overexpression of AURKA and HDM2 in human gastric cancer samples (P < 0.05).

CONCLUSION

Collectively, our novel findings indicate that AURKA promotes tumor growth and cell survival through regulation of HDM2-induced ubiquitination and inhibition of P53. Clin Cancer Res; 20(1); 76-86. ©2013 AACR.

A systematic approach to therapeutic target selection in oesophago-gastric cancer

OBJECTIVE

The success of personalised therapy depends on identification and inhibition of the oncogene(s) on which that tumour is dependent. We aimed to determine whether a receptor tyrosine kinase (RTK) array could be used to select the most effective therapeutic strategies in molecularly heterogeneous oesophago-gastric adenocarcinomas.

DESIGN

Gene expression profiling from oesophago-gastric tumours (n=75) and preinvasive stages (n=57) identified the active signalling pathways, which was confirmed using immunohistochemistry (n=434). RTK arrays on a cell line panel (n=14) determined therapeutic targets for in vitro cytotoxic testing. Feasibility of this personalised approach was tested in tumour samples (n=46).

RESULTS

MAPK was the most frequently activated pathway (32/75 samples (42.7%)) with progressive enrichment in preinvasive disease stages (p<0.05) and ERK phosphorylation in 148/434 (34.3%) independent samples. Cell lines displayed a range of RTK activation profiles. When no RTKs were activated, tyrosine kinase inhibitors (TKIs) and a Mek inhibitor were not useful (MKN1). In lines with a dominant phosphorylated RTK (OE19, MKN45 and KATOIII), selection of this TKI or Mek in nM concentrations induced cytotoxicity and inhibited Erk and Akt phosphorylation. In cells lines with complex activation profiles (HSC39 and OE33), a combination of TKIs or Mek inhibition (in nM concentrations) was necessary for cytotoxicity and inhibition of Erk and Akt phosphorylation. Human tumours demonstrated diverse activation profiles and 65% of cases had two or more active RTKs.

CONCLUSIONS

The MAPK pathway is commonly activated in oesophago-gastric cancer following activation of a variety of RTKs. Molecular phenotyping can inform a rational choice of targeted therapy.

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.

Epidermal growth factor receptor, phosphatidylinositol-3-kinase catalytic subunit/PTEN, and KRAS/NRAS/BRAF in primary resected esophageal adenocarcinomas: loss of PTEN is associated with worse clinical outcome

Alterations of the epidermal growth factor receptor (EGFR) can be observed in a significant subset of esophageal adenocarcinomas (EACs), and targeted therapy against EGFR may become an interesting approach for the treatment of these tumors. Mutations of KRAS, NRAS, BRAF, and phosphatidylinositol-3-kinase catalytic subunit (PIK3CA) and deregulation of PTEN expression influence the responsiveness against anti-EGFR therapy in colorectal carcinomas. We investigated the prevalence of these events in a collection of 117 primary resected EACs, correlated the findings with EGFR expression and amplification, and determined their clinicopathologic impact. KRAS mutations were detected in 4 (3%) of 117 tumors (3× G12D and 1 G12V mutation). One tumor had a PIK3CA E545K mutation. Neither NRAS nor BRAF mutations were detected. Sixteen (14%) of 117 cases were negative for PTEN expression, determined by immunohistochemistry. Loss of PTEN was observed predominantly in advanced tumor stages (P = .004). There was no association between PTEN and EGFR status. Loss of PTEN was associated with shorter overall and disease-free survival (P < .001 each) and also an independent prognostic factor in multivariate analysis (P = .015). EGFR status had no prognostic impact in this case collection. In summary, loss of PTEN can be detected in a significant subset of EAC and is associated with an aggressive phenotype. Therefore, PTEN may be useful as a prognostic biomarker. In contrast, mutations of RAS/RAF/PIK3CA appear only very rarely, if at all, in EAC. A possible predictive role of PTEN in anti-EGFR treatment warrants further investigations, whereas determination of RAS/RAF/PIK3CA mutations may only have a minor impact in this context.

The combination of alisertib, an investigational Aurora kinase A inhibitor, and docetaxel promotes cell death and reduces tumor growth in preclinical cell models of upper gastrointestinal adenocarcinomas

BACKGROUND

Upper gastrointestinal adenocarcinomas (UGCs) respond poorly to current chemotherapeutic regimes. The authors and others have previously reported frequent Aurora kinase A (AURKA) gene amplification and mRNA and protein overexpression in UGCs. The objective of the current study was to determine the therapeutic potential of alisertib (MLN8237) alone and in combination with docetaxel in UGCs.

METHODS

After treatment with alisertib and/or docetaxel, clonogenic cell survival, cell cycle analyses, Western blot analyses, and tumor xenograft growth assays were carried out to measure cell survival, cell cycle progression, apoptotic protein expression, and tumor xenograft volumes, respectively.

RESULTS

By using the AGS, FLO-1, and OE33 UGC cell lines, which have constitutive AURKA overexpression and variable tumor protein 53 (p53) status, significantly enhanced inhibition of cancer cell survival was observed with alisertib and docetaxel treatment in combination (P < .001), compared with single-agent treatments. Cell cycle analyses, after 48 hours of treatment with alisertib, produced a significant increase in the percentage of polyploidy in UGC cells (P < .01) that was further enhanced by docetaxel (P < .001). In addition, an increase in the percentage of cells in sub-G1-phase observed with alisertib (P < .01) was significantly enhanced with the combination treatment (P < .001). Western blot analysis demonstrated higher induction of cleaved caspase 3 protein expression with the combined treatment compared with single-agent treatments. In addition, FLO-1 and OE33 cell xenograft models demonstrated enhanced antitumor activity for the alisertib and docetaxel combination compared with single-agent treatments (P < .001).

CONCLUSIONS

The current study demonstrated that alisertib combined with docetaxel can mediate a better therapeutic outcome in UGC cell lines.

pERK activation in esophageal carcinomas: clinicopathological associations

MAPK (mitogen-activated protein kinase) pathway is considered a control regulator in various malignant tumors but its role in esophageal carcinomas remains elusive. In our study, we examined the possible prognostic significance of MAPK pathway in human esophageal cancer. We searched for mutations in exons 18-21 of EGFR gene, codons 12 and 13 of K-RAS gene and exon 15 of B-RAF gene by high resolution melting analysis (HRMA) and pyrosequencing in 44 esophageal carcinomas. Immunohistochemistry was performed in 29 cases in order to evaluate expression levels of pERK (extracellular-signal regulated kinase). In one laser microdissected squamous cell carcinoma, a somatic K-RAS mutation at codon 12 was detected, whereas none of the cases displayed mutations in EGFR and B-RAF genes. Elevated nuclear as well as cytoplasmic pERK expression (100% and 62% of cases respectively) was observed independently of EGFR and B-RAF mutational status. Increasing pERK nuclear and cytoplasmic expression as well as the intensity of nuclear staining was found to be significantly correlated with tumor grade in univariate and multivariate statistical analysis. Our findings depict the presence of activated ERK despite the low frequency of upstream alterations, implicating ERK activation in the acquisition of a more aggressive phenotype in esophageal cancer.

Phase II trial of modified FOLFOX6 and erlotinib in patients with metastatic or advanced adenocarcinoma of the oesophagus and gastro-oesophageal junction

BACKGROUND

There is increased recognition that cancers of the upper GI tract comprise distinct epidemiological and molecular entities. Erlotinib has shown activity in patients with adenocarcinoma of the oesophagus/gastro-oesophageal junction (GEJ), but not in distal gastric cancer. mFOLFOX6 is one of several active regimens used to treat adenocarcinoma of the Eso/GEJ. This study evaluates the efficacy and safety of mFOLFOX6 and erlotinib in patients with metastatic or advanced Eso/GEJ cancers.

METHODS

Patients with previously untreated advanced or metastatic Eso/GEJ adenocarcinoma are treated with oxaliplatin 85 mg m(-2), 5-FU 400 mg m(-2), LV 400 mg m(-2) on day 1, 5-FU 2400 mg m(-2) over 48 h and erlotinib 150 mg PO daily. Treatment was repeated every 14 days. The primary objective was response rate (RR), secondary objectives include toxicity, progression-free survival (PFS), overall survival (OS) and to correlate clinical outcome with expression patterns and molecular alterations in the epidermal growth factor receptor-dependent pathways.

RESULTS

A total of 33 patients were treated and evaluable: there were two complete responses, 15 partial responses for an objective RR of 51.5% (95% CI, 34.5-68.6%). Median PFS was 5.5 months (95% CI, 3.1-7.5 months) and median OS was 11.0 months (95% CI, 8.0-17.4 months). The most common grade 3-4 toxicities were: diarrhoea (24%), nausea/vomiting (11%), skin rash (8%) and peripheral neuropathy (8%). The frequency of alterations was KRAS mutations (8%), EGFR mutations (0%) and HER2 amplification (19%).

CONCLUSION

In patients with Eso/GEJ adenocarcinoma, mFOLFOX6 and erlotinib is active, has an acceptable toxicity profile and FOLFOX ± erlotinib could be considered for further development.

Evidence for DNA damage checkpoint activation in barrett esophagus

Barrett esophagus is an epithelial metaplasia that predisposes to adenocarcinoma. Better markers of cancer risk are urgently needed to identify those patients who are likely to benefit most from emerging methods of endoscopic ablation. Disease progression is associated with genomic DNA changes (segmental gains, losses, or loss of heterozygosity). Although these changes are not easily assayed directly, we hypothesized that the underlying DNA damage should activate a DNA damage response (DDR), detectable by immunohistochemical (IHC) assays of checkpoint proteins and the resulting replicative phase cell cycle delays. Surgical specimens and endoscopic biopsies (N = 28) were subjected to IHC for the cell cycle markers cyclin A and phosphorylated histone H3 (P-H3), the DDR markers gammaH2AX and phosphorylated ATM/ATR substrates (P-ATM/ATRsub), and the DNA damage-responsive tumor suppressors p16 and p53. Correlations were made with histologic diagnoses. The fractions of cells that stained for cyclin A, P-H3, and gammaH2AX increased in parallel in dysplastic tissue, consistent with checkpoint-mediated cell cycle delays. Foci of nuclear gammaH2AX and P-ATM/ATRsub were demonstrated by standard and confocal immunofluorescence. Staining for p16 was more prevalent in early-stage disease with lower staining for gammaH2AX and P-H3. Staining for p53 was moderately increased in some early-stage disease and strongly increased in some advanced disease, consistent with checkpoint-mediated induction and mutational inactivation of p53, respectively. We suggest that IHC for DDR-associated markers may help stratify risk of disease progression in Barrett.

Identification of EGFR and KRAS mutations in Chinese patients with esophageal squamous cell carcinoma

The prognosis of esophageal squamous cell carcinoma (ESCC) is poor. It is urgent to improve this situation. Epidermal growth factor receptor (EGFR)-targeted therapy possesses a promising clinical efficacy. Mutations of EGFR and V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) have been identified in esophageal carcinoma, but corresponding Chinese data are limited. So we investigated the mutation status of EGFR and KRAS in Chinese patients with ESCC, and explored their correlations with clinicopathological features. Formalin-fixed paraffin-embedded surgically resected tumor samples were obtained from 50 randomly selected Chinese patients with ESCC. EGFR mutations in exons 18-21 were detected by Scorpions amplification refractory mutation system technology. KRAS mutations in codons 12, 13 were detected by direct sequencing of polymerase chain reaction products. The correlations between clinicopathological features and the mutation status of EGFR and KRAS were analyzed using the Statistical Package for the Social Sciences. In the present study, EGFR mutations were found in 7 (14%) out of 50 patients, including G719X missense mutation (n= 1), in-frame deletion (n= 2), and L858R missense mutation (n= 5). Six (12%) out of 50 patients had KRAS mutations in codon 12. Concurrent EGFR and KRAS mutations were detected in one sample. The presences of EGFR and KRAS mutations were not associated with gender, age, smoking history, cell differentiation, or cancer stage. In conclusion, the incidence of EGFR mutations in Chinese patients with ESCC was higher than that of previous reports, and the incidence of KRAS mutations was not low. EGFR and KRAS mutations were mainly located in exons 19 and 21 and codon 12, respectively. Unlike in NSCLC, concurrent EGFR and KRAS mutations existed.

Biology of Barrett's esophagus and esophageal adenocarcinoma

The past few years have brought new advances in our understanding of the molecular mechanisms underlying the development of Barrett's esophagus and esophageal adenocarcinoma. Although knowledge of the genetic basis for these conditions has not yet translated into clinically useful biomarkers, the current pace of biomedical discovery holds endless possibilities for molecular medicine to improve the diagnosis and management of patients with these conditions. This article provides a useful conceptual basis for understanding the molecular events involved in the making of Barrett metaplasia and in its neoplastic progression, and provides a rationale for evaluating studies on the application of molecular medicine to the diagnosis and management of patients with Barrett's esophagus and esophageal adenocarcinoma.

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.

Malignant transformation of non-neoplastic Barrett's epithelial cells through well-defined genetic manipulations

Background

Human Barrett's cancer cell lines have numerous, poorly-characterized genetic abnormalities and, consequently, those lines have limited utility as models for studying the early molecular events in carcinogenesis. Cell lines with well-defined genetic lesions that recapitulate various stages of neoplastic progression in Barrett's esophagus would be most useful for such studies.

Methodology/Principal Findings

To develop such model cell lines, we started with telomerase-immortalized, non-neoplastic Barrett's epithelial (BAR-T) cells, which are spontaneously deficient in p16, and proceeded to knock down p53 using RNAi, to activate Ras by introducing oncogenic H-Ras^G12V, or both. BAR-T cells infected with either p53 RNAi or oncogenic H-Ras^G12V alone maintained cell-to-cell contact inhibition and did not exhibit anchorage-independent growth in soft agar. In contrast, the combination of p53 RNAi knockdown with expression of oncogenic H-Ras^G12V transformed the p16-deficient BAR-T cells, as evidenced by their loss of contact inhibition, by their formation of colonies in soft agar, and by their generation of tumors in immunodeficient mice.

Conclusions/Significance

Through these experiments, we have generated a number of transformed and non-transformed cell lines with well-characterized genetic abnormalities recapitulating various stages of carcinogenesis in Barrett's esophagus. These lines should be useful models for the study of carcinogenesis in Barrett's esophagus, and for testing the efficacy of chemopreventive and chemotherapeutic agents.

Circulating microRNAs: Novel biomarkers for esophageal cancer

Esophageal carcinogenesis is a multi-stage process, involving a variety of changes in gene expression and physiological structure change. MicroRNAs (miRNAs) are a class of small non-coding endogenous RNA molecules. Recent innovation in miRNAs profiling technology have shed new light on the pathology of esophageal carcinoma (EC), and also heralded great potential for exploring novel biomarkers for both EC diagnosis and treatment. Frequent dysregulation of miRNA in malignancy highlights the study of molecular factors upstream of gene expression following the extensive investigation on elucidating the important role of miRNA in carcinogenesis. We herein present a thorough review of the role of miRNAs in EC, addressing miRNA functions, their putative role as oncogenes or tumor suppressors and their potential target genes. The recent progresses in discovering the quantifiable circulating cancer-associated miRNAs indicate the potential clinical use of miRNAs as novel minimally invasive biomarkers for EC and other cancers. We also discuss the potential role of miRNAs in detection, screening and surveillance of EC as miRNAs can be a potential target in personalized treatment of EC.

Silencing of tumor necrosis factor receptor 1 by siRNA in EC109 cells affects cell proliferation and apoptosis

Tumor necrosis factor receptor 1 (TNFR1) is a membrane receptor able to bind TNF-α or TNF-β. TNFR1 can suppress apoptosis by activating the NF-κB or JNK/SAPK signal transduction pathway, or it can induce apoptosis through a series of caspase cascade reactions; the particular effect may depend on the cell line. In the present study, we first showed that TNFR1 is expressed at both the gene and protein levels in the esophageal carcinoma cell line EC109. Then, by applying a specific siRNA, we silenced the expression of TNFR1; this resulted in a significant time-dependent promotion of cell proliferation and downregulation of the apoptotic rate. These results suggest that TNFR1 is strongly expressed in the EC109 cell line and that it may play an apoptosis-mediating role, which may be suppressed by highly activated NF-κB.

MicroRNA expression signatures in Barrett's esophagus and esophageal adenocarcinoma

PURPOSE

Esophageal adenocarcinoma is a highly aggressive malignancy that frequently develops from Barrett's esophagus, a premalignant pathologic change occurring in the lower end of the esophagus. Identifying Barrett's esophagus patients at high risk of malignant transformation is essential to the prevention of esophageal adenocarcinoma. Although microRNA (miRNA) expression signatures have been associated with the etiology and prognosis of several types of cancers, their roles in the development of esophageal adenocarcinoma have not been extensively evaluated.

EXPERIMENTAL DESIGN

In this study, we analyzed the expression patterns of 470 human miRNAs using Agilent miRNA microarray in 32 disease/normal-paired tissues from 16 patients diagnosed with Barrett's esophagus of either low- or high-grade dysplasia, or esophageal adenocarcinoma.

RESULTS

Using unsupervised hierarchical clustering and class comparison analyses, we found that miRNA expression profiles in tissues of Barrett's esophagus with high-grade dysplasia were significantly different from their corresponding normal tissues. Similar findings were observed for esophageal adenocarcinoma, but not for Barrett's esophagus with low-grade dysplasia. The expression patterns of selected miRNAs were further validated using quantitative reverse transcription real-time PCR in an independent set of 75 pairs of disease/normal tissues. Finally, we identified several miRNAs that were involved in the progressions from low grade-dysplasia Barrett's esophagus to esophageal adenocarcinoma.

CONCLUSIONS

We showed that miRNAs were involved in the development and progression of esophageal adenocarcinoma. The identified significant miRNAs that may become potential targets for early detection, chemoprevention, and treatment of esophageal cancer.

Cigarette smoking and K-ras mutations in pancreas, lung and colorectal adenocarcinomas: etiopathogenic similarities, differences and paradoxes

Surprisingly different frequencies and patterns of K-ras mutations are observed in human adenocarcinomas of the pancreas, colorectum and lung. Their respective relationships with smoking are apparently paradoxical. We evaluated all the available types of clinical and epidemiological studies on the relationship between tobacco smoking and the occurrence of K-ras mutations in human adenocarcinomas of the pancreas, colorectum and lung. We identified 8, 7 and 12 studies that analyzed the relationship between K-ras mutations and tobacco smoking in human neoplasms of the pancreas, colorectum and lung, respectively. A meta-analysis was undertaken for each site separately. In pancreatic adenocarcinomas lifetime history of tobacco consumption was not significantly associated with the frequency of K-ras mutations (OR=1.26; 95% CI=0.82-1.94). Similarly, no association was observed between smoking and K-ras mutations in colorectal adenocarcinomas (OR=0.94; CI=0.79-1.12), neither when colorectal adenomas and adenocarcinomas were jointly analyzed (OR=0.96; 95% CI=0.83-1.13). In lung adenocarcinoma, where only 15-25% of cases harbor a K-ras mutation, tumors from smokers were more likely to have K-ras mutations than tumors from non-smokers (OR=3.67; 95% CI=2.47-5.45). Furthermore, in lung adenocarcinomas K-ras mutations have a pattern different from that in pancreatic and colorectal adenocarcinomas. Results support the hypothesis that smoking influences the risk of pancreatic cancer - and possibly colorectal cancer - through events other than K-ras mutations. In adenocarcinoma of the lung, smoking may play a role in the occurrence of K-ras mutations. If the influence of tobacco products in the induction, acquisition and persistence of K-ras mutations had some tissue specificity, or was dependent on different factors in different organs, the corresponding mechanisms would deserve detailed research.

Clinical relevance of EGFR- and KRAS-status in colorectal cancer patients treated with monoclonal antibodies directed against the EGFR

The epidermal growth factor receptor (EGFR) plays an important role in tumorigenesis and tumor progression of colorectal cancer (CRC). As a result, the EGFR has evolved as a relevant target in the treatment of metastatic CRC. KRAS serves as a mediator between extracellular ligand binding and intracellular transduction of signals from the EGFR to the nucleus. The presence of activating KRAS mutations has been identified as a potent predictor of resistance to EGFR-directed antibodies such as cetuximab or panitumumab. These agents should therefore be applied only in tumors with a wild-type status of the KRAS gene. Further parameters of resistance are lack of EGFR amplification, PTEN loss or BRAF mutation. However, they are less well studied or associated with less consistent data and therefore require prospective analyses before integration into clinical decision making. Future studies need to identify patterns of single or multiple mutations to further increase the power of patient selection for anti-EGFR therapy. While molecular parameters help to predict treatment efficacy upfront, skin toxicity has been accepted as an independent predictor of response during exposure to anti-EGFR therapy.

Esophageal adenocarcinoma arising in Barrett esophagus

The major risk factors for esophageal adenocarcinoma are gastroesophageal reflux disease (GERD) and Barrett esophagus, a squamous-to-columnar cell metaplasia that predisposes to malignancy. Adenocarcinomas in Barrett esophagus are thought to arise through a sequence of growth-promoting, genetic alterations that accumulate until the cells have acquired the physiologic hallmarks of cancer proposed by Hanahan and Weinberg. Moreover, GERD and Barrett esophagus are associated with chronic esophagitis, and inflammation is a well known risk factor for cancer formation. The cell that gives rise to Barrett metaplasia is not known. It has been proposed that the metaplasia may arise from a change in the differentiation pattern of stem cells that either reside in the esophagus or are recruited to the esophagus from the bone marrow. Alternatively, it is possible that Barrett metaplasia develops through the conversion of one differentiated cell type into another. Regardless of the cell of origin, Barrett metaplasia ultimately must be sustained by stem cells, which might be identified by intestinal stem cell markers. An emerging concept in tumor biology is that cancer stem cells are responsible for sustaining tumor growth. If Barrett cancers develop from Barrett stem cells, then a therapy targeted at those stem cells might prevent esophageal adenocarcinoma. This report reviews the risk factors for Barrett esophagus and esophageal adenocarcinoma, the mechanisms by which genetic alterations might contribute to carcinogenesis in Barrett esophagus, and the role of stem cells in the development of Barrett metaplasia and adenocarcinoma.

Statins in esophageal cancer cell lines: promising lead?

Barrett's-associated esophageal adenocarcinoma (BEAC) is an important health concern in many western populations owing to its increasing incidence and the paucity of effective treatments. Statins have recently been suggested to induce anticancer effects against a variety of cancers in several, but not all, in vitro, in vivo, and epidemiologic studies. In the accompanying article by Ogunwobi and Beales, three statins were shown to inhibit proliferation and stimulate apoptosis in two EAC cell lines. These effects were achieved by reducing Ras, extracellular signal-regulated kinase (ERK), and protein kinase B (Akt)-related cellular signaling. Although these results are promising, they are clearly preliminary, and much additional work is needed to confirm or refute the potential anticancer effects of statins in human BEAC. In addition, the work of Ogunwobi and Beales highlights the importance of developing better, more predictive in vitro and in vivo models of BEAC, and of taking promising, low-risk agents, such as statins, into early-phase therapeutic and preventive clinical trials involving cancer patients and patients with Barrett's metaplasia/dysplasia, respectively.

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.

New Molecular Concepts of Barrett’s Esophagus: Clinical Implications and Biomarkers

Barrett's esophagus (BE) represents the most serious histological consequence of gastroesophageal reflux disease (GERD) that develops in 5-10% of patients with GERD. Given that BE is the only known precursor to esophageal adenocarcinoma (EA), a systematic endoscopic biopsy protocol can detect EAs at an early stage. However, endoscopic and histopathological evaluation of BE are not adequate for effective screening of high risk patients. Therefore, molecular abnormalities associated with BE have been considered as surrogate markers and their use as such is proposed. Flow cytometry is the most useful adjunct to histology, and ploidy status of BE is an independent risk factor. Cyclin D1 overexpression is inversely correlated with survival in EA. C-erbB2 (+) patients have poorer prognosis. High plasma adenomatous polyposis coli levels correlate with reduced patient survival. p53 expression allows patient risk for EA stratification. Nuclear factor-kappaB overexpression inversely correlates with good response to adjuvant chemotherapy and radiotherapy in EA. Patients with cyclooxygenase-2 overexpression have reduced survival rates. Increased E-cadherin staining is associated with shorter survival in EA patients who received chemoradiotherapy. Finally, existing data cannot rule out a correlation between EA and colorectal tumors. Seventeen BE molecular alterations yielded noteworthy clinical implications. Apart from endoscopy and histology, these data allow for better risk stratification for patients with BE and for more efficient and timely therapeutic approaches.

Colonic Paneth cell metaplasia is pre-neoplastic condition of colonic cancer or not?

Background

The carcinogenesis of colorectal cancer has been accepted by a model for a cascade of genetic alterations, named the adenoma-carcinoma sequence. In order to elucidate the carcinogenesis of the colorectal cancer more clearly, the genetic abnormalies of the non-neoplastic mucosal epithelium of the colon and rectum should be investigated. It has been speculated that colonic Paneth cell metaplasia (PaM) is one of the pre-neoplastic mucosa of colonic cancer. Therefore, we studied the propria mucosa of the right colon with PaM from the standpoints of the frequency of the K-ras codon 12 mutations (K-ras), which is initial genetic abnormality in colorectal cancer, and the loss of heterozygosity of microsatellite markers (LOH-MS), which has a relationship to development of colorectal cancer.

Methods

Fifty-two regions with PaM histopathologically from 12 surgically resected right colon specimens were studied. DNA extraction of the colonic mucosa with PaM was obtained using a microdissection method, and the frequency of the K-ras of PaM was investigated by enriched polymerase chain reaction-enzyme linked mini-sequence assay, and the frequency of the LOH-MS (D2S123, D17S250 and D5S346) of PaM was examined by high resolution fluorescenced labeled PCR primers.

Results

K-ras mutation was detected in fifteen regions among 52 PaM (28.9%). All mutations were a single mutation and GGT changed to AGT in eleven and GAT in four. LOH-MS were detected in twenty-one regions among 52 PaM (40.4%) (D2S123: 35.4%, 17/48 regions, D17S250: 13.7%, 7/51 regions, and D5S346: 0%, 0/52 regions). No K-ras mutations and LOH-MS were detected in the controls (Colorectal mucosa with no PaM).

Conclusions

Colonic mucosa with Paneth cell metaplasia may be one of the pre-neoplastic mucosa in the development of the colonic epithelial neoplasia.

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.

K-ras codon 12 mutations of the super-minute dysplasia in Barrett's esophagus by DNA extraction using a microdissection method

The aim of this study was to clarify the histogenesis of Barrett's cancer. First, 28 lesions of the super-minute dysplasia <or= 1 mm in diameter were detected by pathological examinations for Barrett's esophagus. Secondly, the K-ras codon 12 mutations in these super-minute neoplasias of the Barrett's esophagus were examined by DNA extraction using a microdissection. It was found that seven of 28 (25%) super-minute dysplasia lesions in the Barrett's esophagus showed K-ras mutation, and were a single mutation, with AGT being detected in three lesions and GAT being detected in four lesions. Also, these dysplasia lesions could be divided into two groups according to p53-LI. Two among three lesions with p53-LI over 90%, which were considered to be morphologically high grade dysplasia or intramucosal adenocarcinoma, showed K-ras mutations (both lesions: GGT-->AGT), and 5 among 25 lesions with an average p53-LI of 58%, which were considered to be morphologically low grade dysplasia, showed K-ras mutation (four lesions: GGT-->GAT, 1 lesion: GGT-->AGT). This current study shows that some dysplasia lesions have K-ras mutations in their initial condition, whether these atypical tubule lesions are low grade dysplasia or high grade dysplasia (intramucosal adenocarcinoma), and supports the dysplasia-carcinoma sequence in the histogenesis of Barrett's cancer and synchronously suggests that there is a different route to it.

Antireflux surgery for Barrett's oesophagus

Barrett's oesophagus is usually the result of severe reflux disease. Relief of reflux symptoms is the primary aim of treatment in patients with Barrett's oesophagus who do not have high-grade dysplasia. Some studies with medium-term (2-5 years) follow up show that antireflux surgery can provide good or excellent symptom control, with normal oesophageal acid exposure, in more than 90% of patients with Barrett's oesophagus. Antireflux surgery, but not medical therapy, can also reduce duodenal nonacid reflux to normal levels. There is no conclusive evidence that antireflux surgery can prevent the development of dysplasia or cancer, or that it can reliably induce regression of dysplasia, and patients with Barrett's oesophagus should therefore remain in a surveillance programme after operation. Some data suggest that antireflux surgery can prevent the development of intestinal metaplasia (IM) in patients with reflux disease but no IM. The combination of antireflux surgery plus an endoscopic ablation procedure is a promising treatment for patients with Barrett's oesophagus with low-grade dysplasia.

Vascular endothelial growth factor and basic fibroblast growth factor expression in esophageal adenocarcinoma and Barrett esophagus

OBJECTIVE

This study was undertaken to investigate the role of the angiogenic factors vascular endothelial growth factor and basic fibroblast growth factor in the development and progression of Barrett esophagus and adenocarcinomas of the esophagus and gastroesophageal junction.

METHODS

Vascular endothelial growth factor and basic fibroblast growth factor messenger RNA expression levels, relative to the control gene encoding beta-actin, were measured by using a quantitative reverse transcription-polymerase chain reaction method (ABI 7700 Sequence Detector system) in specimens of Barrett intestinal metaplasia (n = 16), dysplasia (n = 11), adenocarcinoma (n = l 5), and matching normal squamous esophageal tissues (n = 35). Vascular endothelial growth factor and basic fibroblast growth factor protein expression and CD31(+) microvessel density were assessed by means of immunohistochemistry in 25 tissue sections that included representative areas for each of these Barrett stages.

RESULTS

Expression levels were significantly increased in adenocarcinoma compared with in either normal squamous mucosa (P <.0001 for both genes) or intestinal metaplasia (vascular endothelial growth factor, P =.002; basic fibroblast growth factor, P <.0001). Vascular endothelial growth factor levels were also significantly higher in cancer tissues compared with dysplasia tissues (P =.024, Mann-Whitney U test). Basic fibroblast growth factor expression was also significantly increased in Barrett dysplastic mucosa compared with in intestinal metaplasia or normal esophageal mucosa. Microvessel density was generally higher in adenocarcinoma compared with in preneoplastic Barrett tissues. The pattern of vascular endothelial growth factor and basic fibroblast growth factor protein expression was similar to the messenger RNA expression pattern, with the exception that mucin-containing goblet cells stained intensely for vascular endothelial growth factor and only weak vascular endothelial growth factor staining was present in some adenocarcinomas.

CONCLUSIONS

Vascular endothelial growth factor and basic fibroblast growth factor messenger RNA expression levels are significantly upregulated in esophageal and gastroesophageal junction adenocarcinomas, suggesting a role for these angiogenic factors in the development of these cancers. Vascular endothelial growth factor and basic fibroblast growth factor messenger RNA expression levels are also increased in some Barrett esophagus tissues, with this increase occurring at an earlier stage for basic fibroblast growth factor than for vascular endothelial growth factor. Basic fibroblast growth factor protein expression pattern is similar to the messenger RNA expression pattern, but unlike the messenger RNA findings, vascular endothelial growth factor protein expression is strongest in goblet cells.

Genetic pathways involved in the progression of Barrett's metaplasia to adenocarcinoma

BACKGROUND

The prediction of which patients with Barrett's metaplasia will develop cancer is difficult. Better genetic characterization of the condition may aid clinicians in devising more effective management and follow-up strategies.

METHODS

A review was undertaken of the accumulated genetic data relating to the progression of squamous epithelium to adenocarcinoma. The normal functions of a number of cancer-related genes are described and an explanation is given of how alterations in these genes interfere with normal cell processes and lead to cancer.

RESULTS AND CONCLUSION

The main genetic alterations accompanying the progression through dysplasia to adenocarcinoma were collated from 135 papers. The principal genetic changes implicated are the loss of p16 gene expression (by deletion or hypermethylation), the loss of p53 expression (by mutation and deletion), the increase in cyclin D1 expression, the induction of aneuploidy and the losses of the Rb, DCC and APC chromosomal loci.

Cellular and molecular mechanisms responsible for progression of Barrett's metaplasia to esophageal carcinoma

Barrett's metaplasia is found in approximately 12% to 18% of patients undergoing upper endoscopy for symptoms of reflux. Barrett's metaplasia is a premalignant condition and remains the number one risk factor for developing esophageal adenocarcinoma. There has been an increase in the incidence of esophageal adenocarcinoma in the past two decades, making it the most rapidly rising cancer in the United States and Western Europe. This article describes the progression from Barrett's metaplasia to esophageal adenocarcinoma and predictors for the development of adenocarcinoma in Barrett's metaplasia. Barrett's metaplasia represents a histological mosaic, with dysplastic tissue adjacent to non-dysplastic tissue. The histologic changes leading to adenocarcinoma are accompanied by alterations at the molecular level, including the accumulation of gene mutations and changes in gene expression. The determination of the molecular events that occur in the transition from normal esophageal squamous mucosa to dysplasia and to esophageal adenocarcinoma have lead to a better understanding of the process of the transformation to adenocarcinoma. This knowledge will lead to better biomarkers to diagnose and assess cancer risk.

Molecular staging of lung and esophageal cancer

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

Clinical significance of p53 mutations in adenocarcinoma of the esophagus and cardia

OBJECTIVE

To compare the frequency and spectrum of p53 gene mutations in adenocarcinomas of the esophagus and cardia and to compare clinical and pathologic features in patients with p53 mutant and nonmutant cancers.

SUMMARY BACKGROUND DATA

The p53 gene is commonly mutated in human cancers, and a p53 mutation is reported to be present in more than 50% of esophageal adenocarcinomas. Although many studies have investigated the frequency of p53 protein overexpression in adenocarcinomas of the esophagus or esophagogastric junction, few studies have assessed the frequency and clinical significance of p53 mutations in these tumors. In particular, the prognostic importance of p53 mutation is uncertain. Adenocarcinomas of the esophagus and cardia share many epidemiologic and pathologic features, but it is controversial whether they represent the same tumor. A comparison of the frequency and spectrum of mutations in adenocarcinomas of the esophagus and cardia would test whether these tumors are also similar at the molecular level.

METHODS

DNA was isolated from microdissected paraffin-embedded tumor tissues of patients who underwent esophagogastrectomy for adenocarcinoma of the esophagus (n = 19), cardia (esophagogastric junction, n = 12), or subcardia (n = 6). Exons 5 to 8 of the p53 gene were analyzed for the presence of mutations using the polymerase chain reaction with single-strand conformation polymorphism and DNA sequencing of bands showing abnormal mobility. The presence of mutation was confirmed by selective hybridization of a mutant-specific oligonucleotide to DNA isolated from the tumor.

RESULTS

p53 mutations were identified in 18 of 37 (48.6%) tumors. Patients with p53 mutant tumors were significantly younger and had a significantly poorer prognosis. There was a similar prevalence of p53 mutations in adenocarcinomas of the esophagus (53%) and cardia (58%). In contrast, mutations were relatively uncommon in subcardia adenocarcinomas (one mutant tumor [17%]). The types of mutations found in the esophageal and the cardia cancers were also similar.

CONCLUSIONS

Adenocarcinomas of the esophagus and cardia have a similar frequency and spectrum of p53 gene mutations, suggesting that these tumors have a common pathogenesis. Patients with mutations are younger, have signs of more advanced disease, and have a poorer prognosis than patients without mutations.