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

From reflux esophagitis to Barrett’s esophagus and esophageal adenocarcinoma

The occurrence of gastroesophageal reflux disease is common in the human population. Almost all cases of esophageal adenocarcinoma are derived from Barrett’s esophagus, which is a complication of esophageal adenocarcinoma precancerous lesions. Chronic exposure of the esophagus to gastroduodenal intestinal fluid is an important determinant factor in the development of Barrett’s esophagus. The replacement of normal squamous epithelium with specific columnar epithelium in the lower esophagus induced by the chronic exposure to gastroduodenal fluid could lead to intestinal metaplasia, which is closely associated with the development of esophageal adenocarcinoma. However, the exact mechanism of injury is not completely understood. Various animal models of the developmental mechanisms of disease, and theoretical and clinical effects of drug treatment have been widely used in research. Recently, animal models employed in studies on gastroesophageal reflux injury have allowed significant progress. The advantage of using animal models lies in the ability to accurately control the experimental conditions for better evaluation of results. In this article, various modeling methods are reviewed, with discussion of the major findings on the developmental mechanism of Barrett’s esophagus, which should help to develop better prevention and treatment strategies for Barrett’s esophagus.

Intestinal metaplasia of the sinonasal mucosa adjacent to intestinal-type adenocarcinoma. A morphologic, immunohistochemical, and molecular study

It has been hypothesized that the development of sinonasal intestinal-type adenocarcinoma (ITAC) occurs through intestinal metaplasia (IM) of the respiratory and/or glandular epithelium. The aim of this study was to characterize the histological, immunohistochemical, and molecular features of sinonasal IM. Histologic slides from 29 consecutive surgical specimens of ITAC were retrieved. Sections were stained for CDX2, cytokeratin 20 (CK20), MUC2, and p53. The status of TP53 gene exons 4-9 was assessed separately in areas of IM and in ITAC. Foci of IM were detected in eight cases (27.5%). They were all positive for CK20 and CDX2, while MUC2 was detected in six cases (75%). In six cases (75%), the metaplastic foci showed signs of dysplasia, including nuclear enlargement with increased nucleus to cytoplasm ratio, nuclear hyperchromasia, loss of nuclear polarity, and presence of prominent nucleoli. P53 nuclear immunoreactivity was observed in four cases. TP53 gene sequencing was successfully performed in six cases and revealed the same mutation in both IM and ITAC in two cases (c.832C > T and c.215G > C), while another ITAC showed a mutation that was not present in the adjacent IM (c.536A > G). In conclusion, our study suggests a possible clonal relationship between areas of sinonasal IM and ITAC, indicating that IM may represent a precursor lesion of ITAC. Improving the knowledge on the morphological and molecular features of IM is a key step to identify reliable biomarkers to determine the risk of sinonasal ITAC development.

Urinary metabolomic signature of esophageal cancer and Barrett's esophagus

Background

Esophageal adenocarcinoma (EAC) often presents at a late, incurable stage, and mortality has increased substantially, due to an increase in incidence of EAC arising out of Barrett’s esophagus. When diagnosed early, however, the combination of surgery and adjuvant therapies is associated with high cure rates. Metabolomics provides a means for non- invasive screening of early tumor-associated perturbations in cellular metabolism.

Methods

Urine samples from patients with esophageal carcinoma (n = 44), Barrett’s esophagus (n = 31), and healthy controls (n = 75) were examined using ¹H-NMR spectroscopy. Targeted profiling of spectra using Chenomx software permitted quantification of 66 distinct metabolites. Unsupervised (principal component analysis) and supervised (orthogonal partial least-squares discriminant analysis OPLS-DA) multivariate pattern recognition techniques were applied to discriminate between samples using SIMCA-P⁺ software. Model specificity was also confirmed through comparison with a pancreatic cancer cohort (n = 32).

Results

Clear distinctions between esophageal cancer, Barrett’s esophagus and healthy controls were noted when OPLS-DA was applied. Model validity was confirmed using two established methods of internal validation, cross-validation and response permutation. Sensitivity and specificity of the multivariate OPLS-DA models were summarized using a receiver operating characteristic curve analysis and revealed excellent predictive power (area under the curve = 0.9810 and 0.9627 for esophageal cancer and Barrett’s esophagus, respectively). The metabolite expression profiles of esophageal cancer and pancreatic cancer were also clearly distinguishable with an area under the receiver operating characteristics curve (AUROC) = 0.8954.

Conclusions

Urinary metabolomics identified discrete metabolic signatures that clearly distinguished both Barrett’s esophagus and esophageal cancer from controls. The metabolite expression profile of esophageal cancer was also discrete from its precursor lesion, Barrett’s esophagus. The cancer-specific nature of this profile was confirmed through comparison with pancreatic cancer. These preliminary results suggest that urinary metabolomics may have a future potential role in non-invasive screening in these conditions.

Association of methylenetetrahydrofolate reductase C677T-A1298C polymorphisms with risk for esophageal adenocarcinoma, Barrett's esophagus, and reflux esophagitis

Incidence of the esophagus adenocarcinoma has been dramatically increasing in Western countries since the last decade. Gastroesophageal reflux disease and Barrett's esophagus are risk factors for adenocarcinoma. Methylenetetrahydrofolate reductase (MTHFR) genes play a key role not only in folate metabolism but also in esophagus, stomach, pancreatic carcinoma, and acute leukemias. Studies have suggested that genetic polymorphisms of MTHFR (C677T) may clarify the causes and events involved in esophageal carcinogenesis. In this study, we evaluated MTHFR C677T and A1298C polymorphisms, and vitamin B12, folate, and plasma homocystein levels in patients with esophageal adenocarcinoma (EAC), Barrett's esophagus (BE), chronic esophagitis, and healthy controls (n = 26, n = 14, n = 30, and n = 30, respectively). The mean age of patients in the EAC and BE groups was significantly higher compared with the control group (P < 0.001, P = 0.003, respectively). In all patient groups, serum folate levels were significantly lower than that of the control group (P < 0.01, P < 0.05, and P < 0.01, respectively). There was no statistically significant association between folate levels and MTHFR gene polymorphisms. No differences were found in terms of MTHFR gene polymorphisms, homocystein, and B12 levels among the groups. MTHFR gene polymorphisms and folate deficiency are not predictors of early esophageal carcinoma. However, further studies using larger series of patients are needed to evaluate the effect of genetic polymorphisms in the folate metabolic pathway and to clarify the role of folate deficiency and folate metabolism in the development of esophagus adenocarcinoma.

Proliferative and anti-apoptotic activity of esophageal mucosa in gastroesophageal reflux disease is not affected by fundoplication: a 4-year follow-up study

BACKGROUND

The role of fundoplication in the prevention of esophageal adenocarcinoma is controversial. Development of cancer is associated with proliferation and anti-apoptosis, for which little data exist regarding their response to fundoplication.

METHODS

Ki-67 and Bcl-2 expression was assessed in the esophagogastric junction (EGJ) and the distal and proximal esophagus of 20 patients with gastroesophageal reflux disease (GERD) treated by fundoplication and in 7 controls. Endoscopy was performed preoperatively and 6 (20 patients) and 48 months (16 patients) postoperatively.

RESULTS

There were positive correlations between Ki-67 and Bcl-2 levels in the EGJ (p > 0.001) and in the distal (p = 0.001) and proximal esophagus (p = 0.013). Compared to the preoperative level, Ki-67 expression was elevated in the distal (p = 0.012) and proximal (p = 0.007) esophagus at 48 months. In addition, compared to control values, Ki-67 expression was lower at the 6-month follow-up in the EGJ (p = 0.037) and the proximal esophagus (p = 0.003), and higher at the 48-month follow-up in the distal esophagus (p = 0.002). Compared to control values, Bcl-2 was lower at 6 months in the EGJ (p = 0.038).

CONCLUSIONS

Proliferative activity after fundoplication increased in the long term in the distal esophagus despite a normal fundic wrap and healing of GERD.

Cdx genes, inflammation, and the pathogenesis of intestinal metaplasia

Intestinal metaplasia (IM) is a biologically interesting and clinically relevant condition in which one differentiated type of epithelium is replaced by another that is morphologically similar to normal intestinal epithelium. Two classic examples of this are gastric IM and Barrett's esophagus (BE). In both, a chronic inflammatory microenvironment, provoked either by Helicobacter pylori infection of the stomach or acid and bile reflux into the esophagus, precedes the metaplasia. The Caudal-related homeodomain transcription factors Cdx1 and Cdx2 are critical regulators of the normal intestinal epithelial cell phenotype. Ectopic expression of Cdx1 and Cdx2 occurs in both gastric IM as well as in BE. This expression precedes the onset of the metaplasia and implies a causal role for these factors in this process. We review the observations regarding the role of chronic inflammation and the Cdx transcription factors in the pathogenesis of gastric IM and BE.

Evaluation of fatty acid synthase expression in oesophageal mucosa of patients with oesophagitis, Barrett's oesophagus and adenocarcinoma

BACKGROUND AND AIM

To evaluate the expression of fatty acid synthase (FAS) in the oesophagitis-Barrett's oesophagus-oesophageal adenocarcinoma sequence compared with p53 and Ki67 expressions, retained for a long time reliable markers of oesophageal cells biological behaviour.

METHODS

In Barrett's oesophagus, oesophagitis and oesophageal adenocarcinoma patients, biopsies were taken from pathologic sites of the mucosa for histological and immuno-histochemical detection of FAS, p53 and Ki67. FAS expression was positive, when a strong granular cytoplasmic staining was observed in oesophageal cells. Ki67 and p53 was defined positive, when nuclear staining was clearly detected at 10x magnification.

RESULTS

A mild expression of FAS was found in 39% of patients with oesophagitis. The amount of FAS expression increased up to 70% in Barrett's oesophagus while this was present in all patients with oesophageal adenocarcinoma (p = 0.0001). In Barrett's oesophagus, p53 was mildly or intensely expressed in 77% and in 15% of cases, respectively, and mildly or intensely expressed in 33% and 67% of patients with oesophageal adenocarcinoma, respectively, (p = 0.0001). Ki67 was mildly expressed in 17% of oesophagitis cases and was absent in the majority of cases. In Barrett's oesophagus, a mild Ki67 expression was present in 46% of cases, and in oesophageal adenocarcinoma it was present prevalently in intense form (67%; p = 0.0001).

CONCLUSIONS

The over-expression of p53, Ki67 and FAS in otherwise similar morphological groups may be useful to stratify patients into selected prognostic subgroups in order to achieve better clinical approaches.

Assessment of chromosomal gains as compared to DNA content changes is more useful to detect dysplasia in Barrett's esophagus brush cytology specimens

Abnormal DNA ploidy status has been suggested as a prognostic factor for Barrett's esophagus progression into esophageal adenocarcinoma (EAC). The aim of the study was to compare image cytometry DNA analysis (ICDA) and fluorescent in situ hybridization (FISH) in the assessment of DNA ploidy status in Barrett's esophagus (BE), and to determine the value of these abnormalities as an adjunct to conventional cytology in detection of dysplasia and EAC. Brush cytology specimens of 90 BE patients were examined using ICDA and FISH with peri-centromeric probes for chromosomes 7 and 17. The results of ICDA and FISH were compared with each other, and with dysplasia grade or EAC as determined by histology and cytology. FISH and ICDA detected abnormalities in 41% (37/90) and 22% (19/90) of the BE cases, respectively. Gains of chromosome 7 and/or 17 were present in 13% of nondysplasia cases, which further increased with dysplasia stage, while overall DNA content aneuploidy was detected predominantly in high grade dysplasia (HGD) and EAC. Using FISH results combined with cytology, we were able to identify IND/LGD (indefinite/ low grade dysplasia) with a sensitivity and specificity of 75 and 76%, respectively. FISH alone detected HGD/EAC with a high sensitivity and specificity of 85 and 84%, which was superior to that of cytology alone. Thus, FISH is more sensitive than ICDA to detect chromosomal abnormalities in BE brush cytology specimens. FISH detects chromosomal gains in early stages of BE and represents a valuable adjunct to conventional cytology to detect dysplasia or EAC.

The usefulness of chromoendoscopy with methylene blue in Barrett's metaplasia and early esophageal carcinoma

BACKGROUND

Barrett's esophagus is a condition that is premalignant for adenocarcinoma of the esophagus and the esophagogastric junction. Early detection of Barrett's metaplasia and dysplasia is very important to decrease the mortality and morbidity from esophageal adenocarcinoma cancer. This study aimed to evaluate the effectiveness of methylene blue-targeted biopsies in the differential diagnosis of intestinal metaplasia, dysplasia, and superficial esophageal carcinoma.

METHODS

A total of 109 patients (43 women and 66 men; average age, 62.32 +/- 10.61 years; range, 33-82 years) were enrolled for the study. Four groups were designed before endoscopic examinations. The patients for these groups were selected at the conventional endoscopy, and then chromoendoscopy was performed. The esophagus was stained with methylene blue, after which six biopsies were taken from stained and unstained areas.

RESULTS

Conventional and chromoendoscopic assessments were compared with histopathologic examination. The sensitivity of chromoendoscopy for Barrett's epithelium was superior to that of conventional endoscopy (p < 0.05). However, there was no statistical difference between the two methods in the diagnosis of esophagitis or esophageal carcinoma (p > 0.05). Stained biopsies were superior to unstained biopsies in terms of sensitivity for Barrett's epithelium and esophageal carcinoma (p < 0.001).

CONCLUSION

Chromoendoscopy is useful for delineating Barrett's epithelium and for indicating the correct location for securing biopsies where dysplasia or early esophageal cancer is suspected.

Reflux injury of esophageal mucosa: experimental studies in animal models of esophagitis, Barrett's esophagus and esophageal adenocarcinoma

Barrett's esophagus (BE), a gastroesophageal reflux associated complication, is defined as the replacement of normal esophageal squamous mucosa by specialized intestinal columnar mucosa with the appearance of goblet cells. The presence of BE is associated with an increased risk of developing esophageal adenocarcinoma (EAC). Although the exposure of gastroduodenal contents to the esophageal mucosa is considered to be an important risk factor for the development of esophagitis, BE and EAC, the mechanisms of reflux esophageal injury are not fully understood. Animal models are now being used extensively to identify the mechanisms of damage and to devise protective and mitigating strategies. Experimental studies on animal models by mimicking the processing of gastroesophageal reflux injury have bloomed during the past decades, however, there is controversy regarding which experimental model for reflux esophagitis, experimental BE and experimental EAC is best. In this review article we aim to clarify the basic understanding of gastroesophageal reflux injury and its complications of BE and EAC, as well as to present current understanding of the reflux experimental models. The animal models of experimental esophageal injury are summarized with focus on the surgical procedures to guide the investigator in choosing or developing a correct animal model in future studies. In addition, our own experimental studies of the animal models are also briefly discussed.

Alterations in manganese superoxide dismutase expression in the progression from reflux esophagitis to esophageal adenocarcinoma

BACKGROUND

Comprehensive understanding of the basic mechanisms in the progression of esophagitis, Barrett esophagus (BE), and esophageal adenocarcinoma (EAC) is urgently needed to develop a management strategy for an effective screening of BE and management of EAC. The aim of this study is to provide a detailed insight of the histology and the cellular and molecular events associated with the genesis of BE and EAC under the esophagoduodenal reflux conditions.

METHODS

Esophagoduodenal anastomosis (EDA) was performed on rats. Animals were weighed weekly and killed after 1, 2, 3, 4, 5, and 6 months. The entire esophagi were examined for macroscopic and microscopic changes and for manganese superoxide dismutase (MnSOD) expression, and TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labeling) assay was performed.

RESULTS

Morphological transformation from esophagitis (100% of animals) to BE (66% of animals) to EAC was observed after 3 months. There was marked loss of MnSOD expression in animals with esophagitis and BE at 1 and 2 months, with an increase in expression during the transformation to dysplasia and EAC. Increased proliferation and apoptosis was observed and reached a peak at months 1 and 2. Greatly increased levels of 8-hydroxy-deoxyguanosine was found during the progression to EAC.

CONCLUSIONS

The morphological transformation of the esophageal mucosa is an adaptive process, and it is an important foundation for the transdifferentiation of BE and cancer. The significant loss of MnSOD expression to achieve BE and then the adaptive increase in expression to achieve dysplasia and EAC during this transformation may represent a predictive marker in identifying patients who will progress from BE to EAC.

Transitioning from preclinical to clinical chemopreventive assessments of lyophilized black raspberries: interim results show berries modulate markers of oxidative stress in Barrett's esophagus patients

Increased fruit and vegetable consumption is associated with decreased risk of a number of cancers of epithelial origin, including esophageal cancer. Dietary administration of lyophilized black raspberries (LBRs) has significantly inhibited chemically induced oral, esophageal, and colon carcinogenesis in animal models. Likewise, berry extracts added to cell cultures significantly inhibited cancer-associated processes. Positive results in preclinical studies have supported further investigation of berries and berry extracts in high-risk human cohorts, including patients with existing premalignancy or patients at risk for cancer recurrence. We are currently conducting a 6-mo chemopreventive pilot study administering 32 or 45 g (female and male, respectively) of LBRs to patients with Barrett's esophagus (BE), a premalignant esophageal condition in which the normal stratified squamous epithelium changes to a metaplastic columnar-lined epithelium. BE's importance lies in the fact that it confers a 30- to 40-fold increased risk for the development of esophageal adenocarcinoma, a rapidly increasing and extremely deadly malignancy. This is a report on interim findings from 10 patients. To date, the results support that daily consumption of LBRs promotes reductions in the urinary excretion of two markers of oxidative stress, 8-epi-prostaglandin F2alpha (8-Iso-PGF2) and, to a lesser more-variable extent, 8-hydroxy-2'-deoxyguanosine (8-OHdG), among patients with BE.

Mitochondrial perturbation attenuates bile acid-induced cytotoxicity

Hydrophobic bile acids such as deoxycholate (DOC) are known to damage liver cells during cholestasis and promote colon cancer. Cellular stresses induced by bile acids, which include mitochondrial and endoplasmic reticulum (ER) stresses, can result in apoptosis. We found that inhibition of mitochondrial complexes I-V with rotenone, thenoyltrifluoroacetone (TTFA), antimycin A, myxothiazol or oligomycin strongly protected against DOC-induced apoptosis of HCT-116 cells. To understand the mechanism of this protection, we explored the ability of these specific inhibitors to reduce DOC-induced mitochondrial and ER stresses. Different inhibitors markedly reduced DOC-induction of mitochondrial condensation, the DOC-induced decrease in mitochondrial membrane potential and the DOC-induced dilatation of the ER (evidence of ER stress). A dramatic induction of nucleolar segregation by antimycin A and myxothiazol, two distinct complex III inhibitors, was also observed. These findings strongly implicate mitochondrial crosstalk with apoptotic signaling pathways and mitochondrial-nucleolar crosstalk in the development of apoptosis resistance in the colon.

Altered expression of TFF-1 and CES-2 in Barrett's Esophagus and associated adenocarcinomas

Identification of biomarkers to recognize individuals with Barrett's esophagus (BE) predisposed to develop malignancy is currently a pressing issue. We utilized gene expression profiling to compare molecular signatures of normal esophagus and stomach, BE, and adenocarcinoma (AC) to identify such potential biomarkers. Over 22,000 genes were analyzed by oligonucleotide microarrays on 38 unique RNA Unsupervised and supervised clusterings were performed on a subset of 2849 genes that varied most significantly across the specimens. Immunohistochemistry (IHC) for two of the significantly differentially expressed gene products was performed on tissue microarrays. Unsupervised clustering identified two discernable molecular BE profiles, one of which was similar to normal gastric tissue ("BE1"), and another that was shared by several of the AC specimens ("BE2"). The BE1 profile included expression of several genes that have been described as tumor-suppressor genes, most notably trefoil factor 1 (TFF-1). The BE2 profile included expression of genes previously found overexpressed in cancers, such as carboxylesterase-2 (CES-2). IHC demonstrated the loss of TFF-1 late in the progression of BE to AC. It also revealed CES-2 as being upregulated in AC documented to have arisen in the presence of BE. These potential biomarkers, as well as the relative expression of genes from BE1 versus those from BE2, may be validated in the future to aid in risk stratification and guide treatment protocols in patients with BE and associated AC.

Gastroesophageal reflux and cancer

The causal relationship between GERD and esophageal adenocarcinoma, although unclear just a few decades ago, now is established fairly well. The physiologic changes and the biocellular alterations of the damaged esophageal mucosa are documented better. Despite this knowledge, the dramatic increase in the incidence of esophageal cancer cannot be explained. The absolute risk of esophageal adenocarcinoma arising from GERD is low, and, at present, does not justify population-screening programs. Still, with the notion that adenocarcinoma of the esophagus is an aggressive cancer once documented, important questions still are in need of answers for patients suffering from reflux symptoms. Patients who have reflux disease are not necessarily symptomatic. It remains unclear if patients experiencing reflux symptoms should undergo mandatory endoscopy with biopsies at the esophagogastric junction. Furthermore, metaplasia of the lower esophagus often is not readily recognizable at endoscopy, and only biopsies can document abnormal histology. A severe and prolonged history of reflux always should orient to the possibility of a reflux-related columnar-lined esophagus. Once documented, Barrett's esophagus needs to be seen as a premalignant condition not necessarily leading to adenocarcinoma formation; despite their increased risk of tumor formation, most patients who have Barrett's esophagus die of other causes. During regular endoscopic follow-up, multilevel circumferential biopsies should document the evolution of the histologic changes in the lower esophagus and at the gastroesophageal junction of these patients. It is the only method available to document the appearance of dysplasia. It still is unclear if medicine or surgery provides the best quality of life and the best protection against the development of dysplasia and the possible progression toward adenocarcinoma formation when intestinal metaplasia is present in the esophagus.

Analysis of protein expression patterns in Barrett's esophagus using MALDI mass spectrometry, in search of malignancy biomarkers

In order to detect early changes of malignant degeneration in Barrett's esophagus (BE), and to reduce the cost of surveillance, molecular biomarkers of early malignancy have been sought, with limited success, using genomic and immunohistochemical tools. We postulate that direct analysis of epithelial proteins using mass spectrometry will provide protein profiles capable of identifying patients at high risk of developing malignancy. Our aim is to find transitional protein signals that show a cancer profile within histologically benign BE, which can be used as indicators of early malignant change. Fourteen fresh-frozen, resected esophageal cancer specimens were analyzed using laser capture microdissection and matrix-assisted laser desorption/ionization mass spectrometry. Samples of squamous epithelium, and both benign and malignant Barrett's epithelium, were compared for differences in protein expression. Reliable differentiation of squamous and Barrett's epithelium was demonstrated. A comparison of benign and malignant Barrett's epithelium identified a number of cancer-specific protein peaks that were deletion or expression variations from benign epithelium. In four instances the proteins (7350, 8446, 10850, and 14693) appeared to be early malignant changes in histologically benign BE. Mass spectrometry performed upon fresh-frozen Barrett's epithelium, obtained by laser-capture microdissection, displays reproducible, tissue-specific, protein profiles. Distinct differences are demonstrated between benign and malignant epithelium, some of which appear to be candidate biomarkers of early malignant change. This technique reliably displays cellular protein expression in esophageal epithelium and deserves further study as a tool to identify early malignant degeneration in BE.

Do 40% of patients resected for barrett esophagus with high-grade dysplasia have unsuspected adenocarcinoma?

Results of studies conducted in the last 2 decades suggest that the detection of high-grade dysplasia in patients with Barrett esophagus is the harbinger of a synchronous adenocarcinoma, which remains undetected even by rigorous biopsy protocols but is discovered during resection of the esophagus. The reported prevalence of synchronous carcinomas ranges from 0% to 75%. Other researchers maintain that appropriate surveillance programs can be used to detect carcinomas at a curable stage and to prevent unnecessary esophagectomies. Both logistical difficulties and potential methodological pitfalls have plagued many studies designed to investigate this issue. A large multicenter study that would stratify participants for hitherto unexplored variables (eg, age, gender, and ethnic background) may be required before the 40% occult cancer prevalence can be either confirmed or refuted. However, the large scale needed for such a study to provide reliable data and new developments in endoscopic imaging (eg, magnification endoscopy and optical coherence tomography) and endoscopic therapy (eg, mucosectomy) are likely to make such a study both ethically unacceptable and logistically and financially unfeasible. Future research should utilize the combination of new endoscopic technologies with the continuing search for validated biomarkers that help predict the biological behavior of Barrett epithelium in individual patients, with a particular focus on the possible development of preneoplastic and neoplastic lesions. Pathologists who chose to shift their focus from the traditional morphological investigation of dysplasia to the search for usable biomarkers can position themselves at the center of innovative research projects that could radically modify the management of patients with Barrett esophagus.

p27 and Barrett's esophagus: a review*

The rising prevalence of Barrett's esophagus and Barrett's associated adenocarcinoma in the Western world has stimulated increasing interest in this disease. This has resulted in a plethora of articles concerning its molecular biology, but the tumor suppressor gene, p27, has received little attention. In this article, we review the literature concerning the role of p27 in Barrett's esophagus and its malignant transformation, and we evaluate its possible role as an important clinical biomarker, as well as potential chemopreventive clinical agents aimed at substituting its antitumoral activity.