Acidic fibroblast growth factor is expressed sequentially in the progression from Barrett's esophagus to esophageal adenocarcinoma

Proposal for an Organ-Specific Chronic Inflammation–Remodeling–Carcinoma Sequence

An organ-specific chronic inflammation–remodeling–carcinoma sequence has been proposed, mainly for the alimentary tract. As representative diseases, gastroesophageal reflux disease, chronic gastritis and inflammatory bowel disease (ulcerative colitis and Crohn’s disease of the colitis type) were adopted for this discussion. Tissue remodeling is such an important part of tumorigenesis in this sequence that an organ-specific chronic inflammation–remodeling–carcinoma sequence has been proposed in detail. Chronic inflammation accelerates the cycle of tissue injury and regeneration; in other words, cell necrosis (or apoptosis) and proliferation result in tissue remodeling in long-standing cases of inflammation. Remodeling encompasses epithelial cell metaplasia and stromal fibrosis, and modifies epithelial–stromal cell interactions. Further, the accumulation of genetic, epigenetic and molecular changes—as well as morphologic disorganization—also occurs during tissue remodeling. The expression of mucosal tissue adapted to chronic inflammatory injury is thought to occur at an early stage. Subsequently, dysplasia and carcinoma develop on a background of remodeling due to continuous, active inflammation. Accordingly, organ-specific chronic inflammation should be ameliorated or well controlled with appropriate monitoring if complete healing is unachievable.

Genetic alterations in a telomerase-immortalized human esophageal epithelial cell line: implications for carcinogenesis

Ectopic expression of viral oncoproteins disrupts cellular functions and limits the value of many existing immortalization models as models for carcinogenesis, especially for cancers without definitive viral etiology. Our newly established telomerase-immortalized human esophageal epithelial cell line, NE2-hTERT, retained nearly-diploid and non-tumorigenic characteristics, but exhibited genetic and genomic alterations commonly found in esophageal cancer, including progressive loss of the p16(INK4a) alleles, upregulation of anti-apoptotic proteins, epithelial-mesenchymal transition, whole-chromosome 7 gain and duplicated 5q arm. Our data also revealed a novel positive regulation of p16(INK4a) on cyclin D1. These findings probably represent early crucial events and mechanisms in esophageal carcinogenesis.

Overexpression of Slug is associated with malignant progression of esophageal adenocarcinoma

AIM: To characterise expression of known E-cadherin repressors; Snail, Slug and Twist in the development of esophageal adenocarcinoma.

METHODS: E-cadherin, Slug, Snail and Twist mRNA expression in Barrett's metaplasia and esophageal adenocarcinoma specimens was examined by real-time reverse transcription-polymerase chain reaction (RT-PCR). Semi-quantitative immunohistochemistry was used to examine cellular localization and protein levels. The effect of Slug on epithelial mesenchymal transition (EMT) markers was examined by transfection of Slug into an adenocarcinoma line OE33.

RESULTS: Cellular localization of Slug in Barrett’s metaplasia was largely cytoplasmic whilst in adenocarcinoma it was nuclear. Semi-quantitative analysis indicated that Slug was more abundant in adenocarcinoma compared to matched Barrett's metaplastic specimens. Snail and Twist were expressed in adenocarcinoma but were cytoplasmic in location and not induced compared to Barrett's mucosa. These observations were supported by mRNA studies where only Slug mRNA was shown to be over-expressed in adenocarcinoma and inversely correlated to E-cadherin expression. Overexpression of Slug in OE33 mediated E-cadherin repression and induced the mesenchymal markers vimentin and fibronectin.

CONCLUSION: Progression to adenocarcinoma is associated with increased Slug expression and this may represent a mechanism of E-cadherin silencing.

Modification of insulin-like growth factor 1 receptor, c-Src, and Bcl-XL protein expression during the progression of Barrett's neoplasia

Oncogenes, growth factors, cell surface receptors, and cell-cycle and apoptotic regulatory proteins have been implicated in the growth regulation and progression of Barrett's-associated neoplasia. Among these, insulin-like growth factor 1 receptor (IGF1-R) and c-Src are reported to be key regulators of mitogenesis and tumorigenesis. In addition, c-Src may exert its transforming capability by inducing increased expression of IGF1-R on the neoplastic cells. Bcl-X(L), a member of the Bcl-2 family, blocks apoptosis and has been reported to increase in Barrett's-associated neoplasia. To study the modifications in IGF1-R, c-Src, and Bcl-X(L) protein expression during the progression of Barrett's-associated neoplasia, we analyzed 34 resected gastroesophagectomy specimens by immunohistochemistry using antibodies to human IGF1-R, c-Src, and Bcl-X(L). In these cases, we found 22 intestinal (Barrett's) metaplasias (IMs), 25 low-grade dysplasias (LGDs), 28 high-grade dysplasias (HGDs), 34 invasive adenocarcinomas (CAs), and 19 lymph node metastases. High IGF1-R cytoplasmic staining was present in 14 of 19 (74%) node metastases, in 28 of 34 (82%) CAs, in 18 of 28 (64%) HGDs, in 13 of 25 (52%) LGDs, and in 5 of 22 (23%) IMs. Strong and diffuse c-Src expression was identified in 17 of 19 (89%) node metastases, in 29 of 34 (85%) Cas, in 26 of 28 (93%) HGDs, in 18 of 25 (72%) LGDs, and in 9 of 22 (41%) IMs. Bcl-X(L) cytoplasmic staining was evident in 12 of 19 (63%) node metastases, in 20 of 34 (59%) Cas, in 20 of 28 (71%) HGDs, in 15 of 25 (60%) LGDs, and in 6 of 22 (27%) IMs. In 11 cases, c-Src activity was measured by kinase assay and reflected the immunohistochemical results. Our data indicate that expression levels of IGF1-R, c-Src, and Bcl-X(L) proteins are coordinately elevated in Barrett's-associated neoplasia. These findings indicate important roles of these growth regulatory proteins in the malignant progression of Barrett's-associated neoplasia.

Barrett esophagus

A number of publications have provided valuable insight into and data on the epidemiology, pathogenesis, diagnosis, risk factor evaluation, and treatment of patients with Barrett esophagus. Although the incidence of esophageal adenocarcinoma has rapidly increased over the past two decades, it is not clear whether there has been a parallel increase in the frequency of Barrett esophagus. The issue of surveillance endoscopy in patients with Barrett esophagus remains controversial; prospective data are still lacking. Bile reflux plays an important role in the pathogenesis of Barrett esophagus; however, this usually occurs in the presence of acid. Newer technology and techniques, including chromoendoscopy, magnification endoscopy, optical coherence tomography, and spectroscopy, have opened the field by providing a more accurate and "nonbiopsy" diagnosis of intestinal metaplasia and dysplasia. The field of biomarkers remains continues to expand and is providing insight into risk stratification of patients with Barrett esophagus. The exact role of acid suppression in patients with this premalignant disease remains controversial, and endoscopic therapies appear promising.