Flow-cytometric analysis of growth-regulatory peptides and their receptors in Barrett's oesophagus and oesophageal adenocarcinoma

Chemoprevention in Barrett's Esophagus: Current Status

Chemoprevention in Barrett's esophagus is currently applied only in research settings. Identifying pathways that can be targeted by safe, pharmaceutical or natural compounds is key to expanding the scope of chemoprevention. Defining meaningful surrogate markers of cancer progression is critical to test the efficacy of chemopreventive approaches. Combinatorial chemoprevention that targets multiple components of the same pathway or parallel pathways could reduce the risk and improve the efficacy of chemoprevention. Here we discuss the role of chemoprevention as an independent or an adjuvant management option in BE-associated esophageal adenocarcinoma.

The dichotomy in carcinogenesis of the distal esophagus and esophagogastric junction: intestinal-type vs cardiac-type mucosa-associated adenocarcinoma

Adenocarcinoma of the distal esophagus and esophagogastric junction continues to rise in incidence. An intestinal metaplasia (Barrett esophagus)-dysplasia-carcinoma sequence induced by gastroesophageal reflux disease is well established. However, a significant number of adenocarcinomas in the vicinity of the esophagogastric junction are seen in the background of gastric/cardiac-type mucosa without intestinal metaplasia. Thus, the aim of this study was to investigate the role of Barrett esophagus (intestinal-type mucosa) in the classification and prognosis of tumors of the distal esophagus and esophagogastric junction. Clinicopathological and molecular characteristics were examined in 157 consecutively resected adenocarcinomas of the distal esophagus and esophagogastric junction and were compared between tumors arising in association with intestinal-type and cardiac-type mucosa. Intestinal-type mucosa-associated adenocarcinomas were more likely to be associated with younger age (P=0.0057), reflux symptoms (P<0.0001), proximal location (P=0.0009), lower T stage (P<0.0001), fewer nodal metastases (P=0.0001), absence of lymphatic (P<0.0001), venous (P=0.0060) or perineural (P<0.0001) invasion. Histologically, intestinal-type mucosa-associated tumors were more likely to be low-grade glandular tumors (P=0.0095) of intestinal or mixed immunophenotype (P=0.015) and express nuclear β-catenin (P=0.0080), whereas tumors arising in a background of cardiac-type mucosa were more frequently associated with EGFR amplification (P=0.0051). Five-year overall survival rate was significantly higher in patients with intestinal-type mucosa-associated tumors (28 vs 9%, P=0.0015), although no survival benefit was seen after adjusting for potential confounders. Our findings support the theory that multiple distinct pathways of tumorigenesis exist in the vicinity of the esophagogastric junction, including one in which tumors arise from dysplastic intestinal metaplasia (intestinal pathway), and one potentially involving dysplasia of the cardiac-type mucosa (non-intestinal pathway). Additional studies are warranted to further clarify their pathogenesis and the molecular mechanisms involved.

Risk factors for neoplastic progression in Barrett’s esophagus

Barrett’s esophagus (BE) confers a significant increased risk for development of esophageal adenocarcinoma (EAC), with the pathogenesis appearing to progress through a “metaplasia-dysplasia-carcinoma” (MDC) sequence. Many of the genetic insults driving this MDC sequence have recently been characterized, providing targets for candidate biomarkers with potential clinical utility to stratify risk in individual patients. Many clinical risk factors have been investigated, and associations with a variety of genetic, specific gastrointestinal and other modifiable factors have been proposed in the literature. This review summarizes the current understanding of the mechanisms involved in neoplastic progression of BE to EAC and critically appraises the relative roles and contributions of these putative risk factors from the published evidence currently available.

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.

REG Ialpha protein expression in Barrett's esophagus

BACKGROUND AND AIM

Accelerated cellular proliferation in Barrett's esophagus has been implicated in Barrett's elongation and malignant transformation. Therefore, growth factors may play important roles in the pathophysiology of Barrett's esophagus. Regenerating gene (REG), an epithelial growth factor, has been reported to link mucosal inflammation and subsequent carcinogenesis in the gastrointestinal tract. The aim of this study was to investigate whether REG is expressed in Barrett's esophagus and to elucidate the relationship between REG protein expression and clinicopathological factors of Barrett's esophagus.

METHODS

Between July 2003 and June 2004, 266 patients with endoscopically and histologically proven Barrett's esophagus were enrolled in this study. Before endoscopic examination, all participants were requested to answer structured questionnaires on gastroesophageal reflux symptoms and drugs usage. Mucin phenotype, cyclooxygenase-2 expression, cellular proliferation, apoptosis and REG Ialpha protein expression were investigated in the biopsy samples taken from Barrett's esophagus. Clinicopathological factors that correlated with REG Ialpha protein expression in patients with Barrett's esophagus were evaluated using multivariate logistic regression analysis.

RESULTS

REG Ialpha protein expression was observed in 48 (18.0%) of 266 patients with Barrett's esophagus by immunohistochemistry. Newly developed squamous re-epithelialization of Barrett's esophagus at biopsy sites, presence of hiatal hernia and aging were shown to correlate with REG Ialpha protein expression.

CONCLUSIONS

The present study is the first to show REG expression in Barrett's esophagus. Expression of REG Ialpha was more frequently observed in patients who showed squamous re-epithelialization of Barrett's esophagus at biopsy sites.

Gain of allelic gene expression for IGF-II occurs frequently in Barrett's esophagus

The IGF-II gene normally exhibits genomic imprinting, a DNA modification that allows the expression of only one of the two inherited alleles. With loss of imprinting, there is a gain of allelic gene expression (GOAGE) due to IGF-II being expressed by both alleles. GOAGE for IGF-II has been demonstrated in a number of malignancies and in normal epithelia surrounding malignancies, but not in epithelia without associated neoplasia. We hypothesized that nonneoplastic Barrett's epithelium might have GOAGE for IGF-II that could facilitate its progression to neoplasia. Endoscopic biopsies were obtained from metaplastic esophageal, normal gastric, and normal duodenal epithelia from 43 patients with Barrett's esophagus. Genomic DNA were analyzed using PCR followed by ApaI restriction enzyme digestion or allele-specific PCR to identify an ApaI polymorphism of IGF-II. cDNA from patients with the ApaI polymorphism were analyzed for IGF-II GOAGE using exon connection PCR, followed by a secondary nested PCR and ApaI restriction enzyme digestion. We found that 13 (30%) of 43 samples of Barrett's metaplasia contained the ApaI polymorphism and were thus informative for IGF-II, and sufficient material was available for GOAGE analysis in 9 of those 13 cases. GOAGE for IGF-II was demonstrated in five (56%) of those nine cases. All patients with GOAGE in Barrett's metaplasia also demonstrated GOAGE in the gastric and duodenal epithelia. In contrast, patients without GOAGE in Barrett's metaplasia also had no GOAGE in their gastric and duodenal epithelia. We conclude that in patients with Barrett's esophagus, GOAGE for IGF-II is found frequently in the metaplastic esophageal epithelium as well as in normal gastric and duodenal epithelia.

Molecular targets for treatment of Barrett's esophagus

SUMMARY. Esophageal cancer is one of the most deadly forms of gastrointestinal cancer with a mortality rate exceeding 90%. The major risk factors for esophageal adenocarcinoma are gastroesophageal reflux disease (GERD) and its sequela, Barrett's esophagus. GERD commonly leads to esophagitis. In a minority of patients however, ongoing GERD leads to replacement of esophageal squamous mucosa with metaplastic, intestinal-type Barrett's mucosa. In the setting of continued peptic injury, Barrett's mucosa can give rise to esophageal adenocarcinoma. Despite the widespread use of potent acid suppressive therapies for patients with GERD, the incidence of esophageal adenocarcinoma, among white men in the USA, the UK and Europe has continued to rise. Cancers in Barrett's esophagus arise through a sequence of genetic events that endow the cells with six essential physiologic hallmarks of cancer as described by Hanahan and Weinberg in 2000. These cancer hallmarks include the ability to proliferate without exogenous stimulation, to resist growth-inhibitory signals, to avoid triggering the programmed death mechanism (apoptosis), to resist cell senescence, to develop new vascular supplies (angiogenesis), and to invade and metastasize. While the acquisition of these essential attributes is not specific to the neoplastic progression of Barrett's esophagus, this review will focus on the genetic alterations that occur in Barrett's cells that contribute to the acquisition of each of the hallmarks. Moreover, potential diagnostic and therapeutic strategies for Barrett's patients aimed at each of these cancer hallmarks will be reviewed.

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.

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.

Molecular and biologic basis of upper gastrointestinal malignancy--esophageal carcinoma

Esophageal cancer is one of the most deadly forms of gastrointestinal cancer. Even though the incidence of esophageal adenocarcinoma has been rising in Western populations over the past two decades, esophageal squamous cell carcinoma remains the predominant type of esophageal malignancy in the remainder of the world. With the recent advances in molecular biology, high-output genome wide screening has provided comprehensive profiles of molecular alterations in human esophageal carcinomas. The elucidation of the basic mechanisms of esophageal carcinogenesis brings with it the promise of developing treatment and preventive strategies that are based on the molecular biology of these tumors. The genetic alterations discussed in this article are not unique to the formation of esophageal carcinomas and represent only a fraction of the molecular changes found in these tumors. The goal of this article is to provide the clinician with a useful conceptual basis for evaluating studies on the molecular mechanisms underlying the development of esophageal carcinomas.

Review article: a conceptual approach to understanding the molecular mechanisms of cancer development in Barrett's oesophagus

Oesophageal adenocarcinoma is one of the most deadly human malignancies. Gastro-oesophageal reflux disease (GERD) has been established as a strong risk factor for oesophageal adenocarcinoma, and more than 40% of adult Americans experience regular GERD symptoms. GERD can be complicated by oesophagitis, and by replacement of oesophageal squamous mucosa with metaplastic, intestinal-type epithelium (Barrett's oesophagus) that is predisposed to malignancy. Cancers in Barrett's oesophagus arise through a sequence of genetic alterations which endow unlimited proliferative capacity upon the cells by affecting components of the cell cycle clock apparatus-the pivotal molecular machinery in the cell nucleus that controls whether a cell will proliferate, differentiate, become quiescent or die. This report describes how the genetic abnormalities that have been recognized in Barrett's oesophagus might promote carcinogenesis through effects on the cell cycle clock machinery. The goal of this review is to provide the clinician with a useful conceptual basis for evaluating studies on the molecular mechanisms underlying the progression from metaplasia to carcinoma in Barrett's oesophagus.

Molecular biology of Barrett's adenocarcinoma

OBJECTIVE

To review the current knowledge on the genetic alterations involved in the development and progression of Barrett's esophagus-associated neoplastic lesions.

SUMMARY BACKGROUND DATA

Barrett's esophagus (BE) is a premalignant condition in which the normal squamous epithelium of the esophagus is replaced by metaplastic columnar epithelium. BE predisposes patients to the development of esophageal adenocarcinoma. Endoscopic surveillance can detect esophageal adenocarcinomas when they are early and curable, but most of the adenocarcinomas are detected at an advanced stage. Despite advances in multimodal therapy, the prognosis for invasive esophageal adenocarcinoma is poor. A better understanding of the molecular evolution of the Barrett's metaplasia to dysplasia to adenocarcinoma sequence may allow improved diagnosis, therapy, and prognosis.

METHODS

The authors reviewed data from the published literature to address what is known about the molecular changes thought to be important in the pathogenesis of BE-associated neoplastic lesions.

RESULTS

The progression of Barrett's metaplasia to adenocarcinoma is associated with several changes in gene structure, gene expression, and protein structure. Some of the molecular alterations already showed promise as markers for early cancer detection or prognostication. Among these, alterations in the p53 and p16 genes and cell cycle abnormalities or aneuploidy appear to be the most important and well-characterized molecular changes. However, the exact sequence of events is not known, and probably multiple molecular pathways interact and are involved in the progression of BE to adenocarcinoma.

CONCLUSIONS

Further research into the molecular biology of BE-associated adenocarcinoma will enhance our understanding of the genetic events critical for the initiation and progression of Barrett's adenocarcinoma, leading to more effective surveillance and treatment.

Computerized quantitative pathology for the grading of dysplasia in surveillance biopsies of Barrett's oesophagus

Decision models for surveillance of Barrett's oesophagus (BO) are governed by the grade of dysplasia on endoscopic biopsy, but subjective grading is prone to observer variation. Computerized morphometry and immunoquantitation can objectively discriminate between different grades of dysplasia in oesophagectomy specimens with BO. The present study evaluated the feasibility of such quantitative analysis on surveillance biopsies of BO. Biopsy criteria for quantitative analysis were defined, excluding 101 (21%) of 472 archival BO surveillance biopsies. In the remaining haematoxylin and eosin (H&E) sections, 105 areas that distinctively displayed no dysplasia (ND), low-grade dysplasia (LGD) or high-grade dysplasia (HGD) were demarcated. Agreement on double-blind examination by two experienced pathologists was reached in 66 areas (63%; kappa: 0.44). For 21 ND/LGD and 11 LGD/HGD disagreement areas, corresponding sections for p53 and Ki67 immunohistochemistry were available. The best combination of two discriminating features was stratification index (SI) with p53 area % for ND versus LGD (89% correct classification), and SI with Ki67 area % for LGD versus HGD (91% correct classification). Fifteen of the 21 ND/LGD disagreement areas could be classified uniquely as either ND or LGD by SI and p53, and eight of the 11 LGD/HGD disagreement areas as either LGD or HGD by SI and Ki67. Correlation coefficients for repeated measurements of SI, Ki67, and p53 by the same observer were 0.94, 0.92, and 0.86, and by two independent observers 0.86, 0.93, and 0.92, respectively. Computerized quantitative pathology on BO surveillance biopsies is feasible provided that well-defined biopsy criteria are used. Using a combination of features associated with cellular differentiation and proliferation, such as SI, p53, and Ki67, quantitative pathological analysis assists in reducing diagnostic variability in the grading of dysplasia during surveillance of BO.

Computerized quantitative pathology for the grading of dysplasia in surveillance biopsies of Barrett's oesophagus

Decision models for surveillance of Barrett's oesophagus (BO) are governed by the grade of dysplasia on endoscopic biopsy, but subjective grading is prone to observer variation. Computerized morphometry and immunoquantitation can objectively discriminate between different grades of dysplasia in oesophagectomy specimens with BO. The present study evaluated the feasibility of such quantitative analysis on surveillance biopsies of BO. Biopsy criteria for quantitative analysis were defined, excluding 101 (21%) of 472 archival BO surveillance biopsies. In the remaining haematoxylin and eosin (H&E) sections, 105 areas that distinctively displayed no dysplasia (ND), low-grade dysplasia (LGD) or high-grade dysplasia (HGD) were demarcated. Agreement on double-blind examination by two experienced pathologists was reached in 66 areas (63%; kappa: 0.44). For 21 ND/LGD and 11 LGD/HGD disagreement areas, corresponding sections for p53 and Ki67 immunohistochemistry were available. The best combination of two discriminating features was stratification index (SI) with p53 area % for ND versus LGD (89% correct classification), and SI with Ki67 area % for LGD versus HGD (91% correct classification). Fifteen of the 21 ND/LGD disagreement areas could be classified uniquely as either ND or LGD by SI and p53, and eight of the 11 LGD/HGD disagreement areas as either LGD or HGD by SI and Ki67. Correlation coefficients for repeated measurements of SI, Ki67, and p53 by the same observer were 0.94, 0.92, and 0.86, and by two independent observers 0.86, 0.93, and 0.92, respectively. Computerized quantitative pathology on BO surveillance biopsies is feasible provided that well-defined biopsy criteria are used. Using a combination of features associated with cellular differentiation and proliferation, such as SI, p53, and Ki67, quantitative pathological analysis assists in reducing diagnostic variability in the grading of dysplasia during surveillance of BO.

Eradication of Helicobacter pylori normalizes elevated mucosal levels of epidermal growth factor and its receptor

OBJECTIVE

Helicobacter pylori (H. pylori) infection has been linked to gastric cancer. The factors that promote carcinogenesis remain unknown. Epidermal growth factor (EGF) has been shown to be a potent epithelial mitogen and oncoprotein when sustained over expression occurs. Our aim was to compare gastric mucosal levels of EGF and its receptor (EGFR) among controls, H. pylori infected subjects, and subjects following H. pylori eradication using quantitative flow cytometric analysis.

METHODS

Patients referred for evaluation of dyspepsia underwent EGD and six antral biopsies were performed (two each for rapid urease testing (RUT), histopathology, and flow cytometry). Controls were those found to be H. pylori negative while subjects had confirmed infection. The study patients were treated, then had repeat EGD with biopsies.

RESULTS

There were 17 controls and 28 cases. Mean EGF and EGFR values were 2.69 and 2.46 for controls and 4.67 and 4.64 for subjects. Subjects' mean EGF was 73% higher (p = .035) and EGFR was 88% higher (p = 0.029) than controls. After treatment, the subjects' mean values declined 55% (p = 0.0001) for EGF and 40% (p = 0.002) for EGFR. Three subjects had persistent infection and showed no change in their EGF/EGFR levels. No difference was found among factor levels with respect to endoscopic findings.

CONCLUSIONS

Both EGF and EGFR from gastric antral biopsies are increased nearly 2-fold in infection with H. pylori. Infection eradication reduces levels of both factors to those of controls. One major pathogenic mechanism for gastric mucosal hyperproliferation and possibly carcinogenesis related to H. pylori may be the over expression of EGF and increased receptor density of EGFR on gastric mucosal cells.

The molecular basis for carcinogenesis in metaplastic columnar-lined esophagus

A wide variety of biologic events and mechanisms appear to have roles in the development and progression of Barrett's esophagus-associated neoplastic lesions. Figure 5 is a schematic depiction of these events. This is known as an infernogram (named after Dante's Inferno) (S. Kern, unpublished presentations, 1996). Events at the bottom rings of the inferno are high-frequency mutations; nearer to the top of the inferno are the less common events. The next several years promise many further discoveries of not only high-frequency and low-frequency events, but also their application. Some of the molecular alterations already studied show promise as markers for early cancer detection or prognostication. Eventually, applications of these discoveries should yield new and more effective means of preventing and treating the deadly complications of this troublesome premalignant condition.

Biomarkers for malignancy in the columnar-lined esophagus

The biological mechanisms underlying the progression from normal esophageal squamous mucosa to Barrett's epithelium associated with dysplasia and finally to esophageal adenocarcinoma is becoming increasingly well understood. Histologic determination of Barrett's-associated dysplasia remains of paramount importance; however, genetic and biochemical biomarkers of Barrett's metaplasia and dysplasia will facilitate clinical diagnosis, endoscopic surveillance, and monitoring of new therapeutic interventions as they evolve. This article covers conventional and novel biomarkers in Barrett's esophagus.

Morphological analysis of gastro-esophageal diseases by molecular cell techniques

The molecular cell sciences have had a great impact in the analysis of the genetic and epigenetic events of esophageal and gastric tumorigenesis. In other regions of the alimentary tract such as the colon, the serial identification of the molecular events in the corresponding morphological lesions is perhaps most advanced. This is, in part, due to the relative ease of the histological characterisation of the premalignant lesions. In this regard the analysis of morphological and molecular adaptation in the alimentary tract is inextricable. This review aims, therefore, to judiciously assess the relative applications of contemporary techniques in investigative histopathology.

Expansion of the Ki-67 proliferative compartment correlates with degree of dysplasia in Barrett's esophagus

BACKGROUND

Barrett's esophagus is a histologically defined premalignant lesion of the esophagus in which normal squamous epithelium is replaced by intestinalized columnar epithelium. In a multistep progression from Barrett's esophagus to fully developed carcinoma, accelerated proliferation may indicate or precede genomic instability and, therefore, may be an important factor in the pathogenesis and/or prediction of malignant transformation. Ki-67 is a nuclear antigen expressed in proliferating cells, (G1, S, G2, and M phases) but not in resting cells (G0 phase). This study was undertaken to determine if Ki-67 expression correlates with the degree of dysplasia and if Ki-67 expression can help to differentiate those patients with or without dysplasia.

METHODS

The Ki-67 proliferation fraction in 87 paraffin embedded esophageal biopsies from 43 patients with the Ki-67 antibody (MIB-1) was analyzed using immunohistochemistry. Using a computerized proliferation index program (QNA v2.54, Becton Dickinson Cellular Imaging Systems, Inc., Elmhurst, IL), a Ki-67 score was derived for the luminal surface, upper esophageal crypt, lower crypt, and underlying glandular zone of the columnar-lined esophagus.

RESULTS

Significant differences in Ki-67 scores were noted in each zone among different histologic categories: normal gastric ([NG] n = 17); Barrett's without dysplasia ([ND] n = 17); low grade dysplasia ([LG] n = 21); high grade dysplasia ([HG] n = 14); and adenocarcinoma ([CA] n = 5). The pattern of Ki-67 expression was associated strongly with each histologic category. The percentage of Ki-67 positive nuclei in each mucosal zone statistically separated high grade from low grade dysplasia (P < 0.001). In high grade dysplastic tissues, the Ki-67 positive nuclei were found predominantly on the surface epithelium and upper crypt zones, whereas in low grade dysplasia, the majority of Ki-67 positive nuclei were found in the lower crypt zone. The number of Ki-67 positive nuclei in each mucosal component also was significantly different in Barrett's esophagus without dysplasia when compared with Barrett's esophagus with low grade dysplastic tissues. (P < 0.001) Staining patterns of indefinite for dysplasia by H & E staining separated into several distinct patterns (five LG, seven ND, one NG) whereas six biopsies with low grade dysplasia had a Ki-67 expression pattern more consistent with that of high grade dysplasia.

CONCLUSION

The Ki-67 staining pattern correlated with histologic findings in Barrett's esophagus and may represent an additional parameter for differentiating patients with or without dysplasia.

Association of transforming growth factor alpha (TGFA) and its precursors with malignant change in Barrett's epithelium: biological and clinical variables

Adenocarcinomas of the gastro-esophageal junction (GEJ) and those arising in Barrett's esophagus (BE) are increasing in the West and have a poorer prognosis than distal stomach cancers. This has been attributed mainly to anatomical location, but biological factors such as growth-regulatory molecules have been implicated. We have investigated the expression of one of these factors, TGF alpha, and its precursor prepro TGF alpha in 82 adenocarcinomas of GEJ (32 resected specimens and 50 biopsies) as well as in 48 BE biopsies without tumor, by immunohistochemistry and by Western-blot analysis. TGF alpha staining was shown in the cytoplasm and membrane of cells. Western blot confirmed that most immunoreactivity was against mature TGF alpha (5.6 kDa), but higher-molecular-weight bands were also identifiable, suggesting some reactivity with prepro protein. TGF alpha expression was more extense and intense in intestinal metaplasia and cancer. The tubular histological type of adenocarcinoma was more often positive than the signet-ring type. Primary tumors with lymph-node metastases also had increased TGF alpha expression. We conclude, therefore, that there is differential regulation of the expression of TGF alpha and its precursors during esophageal tumorigenesis.

Barrett's esophagus, dysplasia, and adenocarcinoma

In Barrett's esophagus the normal stratified squamous epithelium lining the esophagus becomes replaced by metaplastic columnar epithelium containing goblet cells; it develops as a complication of chronic gastroesophageal reflux disease and predisposes the patient to adenocarcinoma. The frequency with which it leads to adenocarcinoma is not established with certainty, but the reported prevalence averages approximately 10% when the diagnosis of Barrett's esophagus is first made. The estimated incidence of adenocarcinoma varies from one in 152 to one in 441 cases per patient year, or a 30- to 125-fold excess risk. Esophageal adenocarcinoma arises only in patients with metaplastic columnar epithelium. Dysplasia precedes adenocarcinoma in Barrett's esophagus and arises from the metaplastic epithelium; it has been proposed as a marker for detecting patients at high risk for developing carcinoma. Problems with the use of dysplasia as a marker for cancer risk include difficulty in differentiating it from reactive change, variability in diagnosis and grading between observers and when the same observer interprets the sections on different occasions, and lack of understanding of its natural history. Methods other than dysplasia for detecting patients at highest risk for developing carcinoma have been sought, but flow cytometric analysis of DNA content is the only one proven to be valuable to date. Flow cytometric abnormalities correlate well with histological progression in Barrett's esophagus. The prevalence of elevated S phase and G2/tetraploid fractions and of aneuploid cell populations increases with histological progression from metaplasia to indefinite/low grade dysplasia to high grade dysplasia and cancer. Flow cytometric abnormalities in endoscopic biopsy specimens identify those patients with a higher risk of progression to high grade dysplasia or adenocarcinoma.

p53 expression in Barrett's oesophagus, dysplasia, and adenocarcinoma using antibody DO-7

Barrett's oesophagus has a well-recognized association with oesophageal adenocarcinoma, with phenotypic progression through dysplasia to malignancy. The nuclear phosphoprotein p53 is a putative tumour suppressor with mutations resulting in both loss of negative growth regulatory function and possible gain of oncogene function. Many mutant forms have a prolonged half-life and are demonstrable with immunohistochemical techniques. We examined 62 endoscopic oesophageal biopsies and 36 oesophageal resections for p53 overexpression using the monoclonal antibody DO-7 on paraffin-embedded tissue. The series included 40 cases of Barrett's metaplasia, 13 cases of dysplasia, and 81 cases of adenocarcinoma. None of the cases of metaplasia was p53-positive, compared with 4/13 cases of dysplasia and 52/81 cases of adenocarcinoma. There was no association between the degree of dysplasia and p53 expression, although a trend emerged of increasing p53 expression with higher tumour grade. We conclude that p53 overexpression is frequent in oesophageal adenocarcinoma and may be related to tumour grade. p53 overexpression is not restricted to neoplastic lesions and mutation of this tumour suppressor may occur early in the malignant progression of Barrett's oesophagus.