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Background: Thymidylate synthase (TS) is known to have a unique 28 bp tandemly repeated sequence in the promoter region, and the majorities of subjects have a heterozygous double repeat/triple repeat genotype in their non-cancerous tissue. Loss of heterozygosity (LOH) at the TS locus is known to occur in cancer patients, but there is no evidence that it is present in precancerous tissue. The aim of this study was to analyze the frequency and timing of LOH at the TS locus in Barrett-associated adenocarcinoma (BA) and its precursory lesions, such as intestinal metaplasia (IM) and dysplasia. Methods: One hundred twenty-three samples (including 37 with gastroesophageal reflux disease (GERD), 29 with IM, 13 with dysplasia, and 44 with BA) were obtained from 100 patients. Biopsies were obtained from the lower esophageal mucosa/IM/dysplasia/BA, when available. Normal squamous tissue from the upper esophagus was taken as a control. All tissues were analyzed for the TS genotype and TS mRNA expression using the real-time reverse-transcription polymerase chain reaction (RT-PCR) method after laser-capture microdissection. Results: Among the patients with informative heterozygous genotype in their control samples, no sample with LOH at the TS locus was observed in the lower esophageal mucosa in GERD patients (0/22 samples). However, 6 out of 21 samples (28.6%) had LOH in IM, 2 of 7 (28.6%) in dysplasia, and 10 of 25 (40.0%) in BA. No significant difference in TS mRNA expression levels was observed between TS genotypes. Conclusion: Our results demonstrate that LOH is a relatively frequent and early event in the IM-BA sequence. [ABSTRACT FROM AUTHOR]

Background: Survivin, a member of the inhibitor-of-apoptosis family, is reported to be overexpressed in esophageal cancer but no data are available about its status in the metaplastic/dysplastic sequence. The aim of this study was to measure survivin gene expression in normal squamous/columnar epithelium and in the various stages of development of Barrett''s adenocarcinoma. Methods: Endoscopic biopsy or operative specimen samples from 5 tissue types were analyzed: (1) squamous epithelium from 3 cm above the gastroesophageal junction in patients with a negative pH study and no histologic injury (n = 17, pH- control); (2) antral tissue from patients with no evidence of Barrett''s, dysplasia, or cancer (n = 29, antral control); (3) specialized intestinal metaplasia from patients with Barrett''s esophagus (n = 16; Barrett''s group); (4) low- or high-grade dysplasia (n = 12, dysplasia group), and (5) adenocarcinoma (n = 45 cancer group). After laser-capture microdissection cellular RNA was extracted from each tissue and reverse transcribed to complementary DNA. Expression levels of survivin were measured by reverse-transcription polymerase chain reaction. Results: Survivin gene expression was greater in columnar (antral) compared with squamous (pH-) control tissues (P = .03). Expression in quiescent Barrett''s epithelium was similar to both control tissues. Expression levels in dysplastic epithelium were greater than in squamous control (P = .01) and Barrett''s tissues (P = .04), but not higher than columnar control tissues, whereas expression in adenocarcinoma was greater than all tissues except dysplasia (P < .001). Conclusions: Survivin expression may be a biomarker in the development of Barrett''s adenocarcinoma that is able to distinguish between quiescent Barrett''s, dysplastic Barrett''s, and Barrett''s adenocarcinoma. [Copyright &y& Elsevier]

Cyclooxygenase (Cox-2) is implicated in the pathogenesis of many cancers including esophageal adenocarcinoma (EAC), whereas the role of the isoform Cox-1 in carcinogenesis is not well understood. To further elucidate the role of these factors in the development of EAC, we measured the gene expressions (mRNA levels) of Cox-2 and Cox-1 by real-time quantitative polymerase chain reaction (QRT-PCR) in tissues from normal esophagus with and without erosive gastroesophageal reflux disease (GERD), Barrett''s esophagus (BE), dysplasia, adenocarcinoma, and in healthy gastric antrum. All tissues were purified by laser capture microdissection from endoscopic or surgical resection specimens. Median Cox-2 gene expression did not differ significantly among the esophageal control groups but was elevated 5-fold in BE, 8-fold in dysplasia and 16-fold in EAC compared to normal esophageal controls with no erosive GERD. Erosive GERD tissue had slightly higher median Cox-2 expression but Cox-2 expression in normal antrum was much higher than that in a normal esophagus, close to that of dysplasia. In contrast to that of Cox-2, Cox-1 expression was significantly decreased in all neoplastic tissues compared to normal controls. Cox-1 and Cox-2 expression varied over a wide range in the neoplastic tissues but over a relatively narrow range in the esophageal normal tissues. The occurrence of substantial alterations in Cox-1 and Cox-2 expression at the BE stage indicates that these are early events in the development of EAC. These results confirm the important role of Cox-2 amplification in the pathogenesis of esophageal adenocarcinoma, but the unexpected down-regulation of Cox-1 raises questions about its role in carcinogenesis. [Copyright &y& Elsevier]

The Barrett''s multistage process is characterized histopathologically by progression from Barrett''s intestinal metaplasia to Barrett''s esophagus with dysplasia and ultimately adenocarcinoma. Understanding of the molecular alterations in this multistage process may contribute to improved diagnosis and treatment. Retinoid X receptors (RXR) play an important role in regulating the morphogenesis, development, growth, and differentiation of cells. Alterations in RXR expression have been observed in a variety of solid tumors; however, the role in Barrett''s esophagus disease has yet to be determined. The aim of this study was to assess the prevalence and timing of RXR messenger RNA expression in the Barrett''s metaplasia-dysplasia-adenocarcinoma sequence and to investigate its role in the development and progression of this disease. We analyzed the mRNA expression of all three RXR subtypes (RXR-alpha, RXR-beta, and RXR-gamma) by using a quantitative real-time reverse transcription–polymerase chain reaction method in 108 specimens from 19 patients with Barrett''s esophagus without carcinoma (BE group), 20 patients with Barrett''s-associated adenocarcinoma (EA group), and a control group of 10 patients without evidence of gastroesophageal reflux disease (CG). RXR-α mRNA expression was significantly decreased (P < 0.001; Kruskal-Wallis test), and RXR-γ was significantly increased (P < 0.001) at higher stages in Barrett''s esophagus. RXR-β expression was highest in Barrett''s tissues and was significantly increased compared to normal squamous tissues (P = 0.01; Wilcoxon test) and adenocarinoma tissues (P = 0.018, Mann-Whitney test). RXR-α and RXR-β mRNA expression was significantly associated in normal squamous esophagus tissues (r2 = 0.49; P < 0.001; Spearman test), Barrett''s tissues (r2 = 0.63; P < 0.001), and adenocarcinoma tissues (r2 = 0.68; P = 0.001). There were significant differences in RXR-α (P = 0.011) and RXR-β (P = 0.005) mRNA expression in histopathologically normal squamous esophagus tissues in patients with cancer and the control group without evidence of gastroesophageal reflux disease. These findings suggest that alterations in the mRNA expression of all three RXR subtypes are frequent events in the development and progression of Barrett''s esophagus and associated adenocarcinoma, that RXR mRNA expression levels may be useful biomarkers for this disease, and that a widespread “field-effect” is present in the normal esophagus of patients with esophageal adenocarcinoma. [Copyright &y& Elsevier]

These studies investigated the role of cyclooxygenase gene expression in esophageal diseases. The study from Germany by Zimmerman et al. detected cytoplasmic cyclooxygenase- 2 (COX-2) protein expression by immunohistochemistry in 156 of 172 (91%) esophageal squamous cell carcinomas (SCC) and in 21 of 27 (78%) Barrett's-associated esophageal adenocarcinomas. There was a wide range in COX-2 immunoreactivity in different cancer specimens, and also within individual specimens. Western blot analysis of COX-2 protein levels was performed for some of the SCC samples, confirming the immunohistochemistry results. No COX-2 protein expression was detected immunohistochemically in Barrett's intestinal metaplasia tissues. There were no significant associations between COX immunoreactivity and tumor stage for either cancer type, except for a higher frequency of local lymph node metastases in SCC patients with low COX-2 expression. In vitro studies using SCC cell lines showed that expression of COX-2 at the mRNA level was associated with production of both COX-2 protein and high prostaglandin (PGE2 and 6-keto-PGFlα) levels. Finally, this study showed that treatment of the COX-2-expressing SCC cells with the COX inhibitors flusolide and NS-398 inhibited prostaglandin synthesis, suppressed proliferative and mitotic activity, and induced widespread apoptosis (the apoptotic effect was assessed with flusolide only). In the non-COX- 2-expressing cell line, none of these effects were observed. The earlier publication, by Wilson et al., from the University of Maryland School of Medicine, used a reverse transcriptase-polymerase chain reaction method to detect elevated COX-2 mRNA levels in 15 of 19 (79%) Barrett's intestinal metaplasia specimens, 2 of 2 (100%) Barrett's dysplasia specimens, and 5 of 5 (100%) Barrett's-associated adenocarcinomas. Increased levels of COX-2 protein, inducible nitric oxide synthase mRNA, and transforming growth factor-α mRNA were also present in similar proportions in Barrett's esophagus and adenocarcinoma tissues. [ABSTRACT FROM AUTHOR]