Proteomic screening of a cell line model of esophageal carcinogenesis identifies cathepsin D and aldo-keto reductase 1C2 and 1B10 dysregulation in Barrett's esophagus and esophageal adenocarcinoma

Esophageal adenocarcinoma (EA) incidence is increasing rapidly and is associated with a poor prognosis. Identifying biomarkers of disease development and progression would be invaluable tools to inform clinical practice. Two-dimensional polyacrylamide gel electrophoresis was used to screen 10 esophageal cell lines representing distinct stages in the development of esophageal cancer. Thirty-three proteins were identified by MALDI-TOF-MS which demonstrated differences in expression across the cell lines. Western blotting and qRT-PCR confirmed increased cathepsin D and aldo-keto reductases 1C2 and 1B10 expression in metaplastic and dysplastic cell lines. Expression of these proteins was further assessed in esophageal epithelium from patients with nonerosive (NERD) and erosive gastro-esophageal reflux disease, Barrett's esophagus (BE) and EA. When compared with normal epithelium of NERD patients, (i) cathepsin D mRNA levels demonstrated a stepwise increase in expression (p<0.05) in erosive, metaplastic and EA tissue; (ii) AKR1B10 expression increased (p<0.05) 3- and 9-fold in erosive and Barrett's epithelium, respectively; and (iii) AKR1C2 levels increased (p<0.05) in erosive and Barrett's epithelium, but were reduced (p<0.05) in EA. These proteins may contribute to disease development via effects on apoptosis, transport of bile acids and retinoid metabolism and should be considered as candidates for further mechanistic and clinical investigations.     

Acid, bile, and CDX: the ABCs of making Barrett's metaplasia

Barrett's esophagus, a squamous-to-columnar cell metaplasia that develops as a result of chronic gastroesophageal reflux disease (GERD), is a risk factor for esophageal adenocarcinoma. The molecular events underlying the pathogenesis of Barrett's metaplasia are poorly understood, but recent studies suggest that interactions among developmental signaling pathways, morphogenetic factors, and Caudal homeobox (Cdx) genes play key roles. Strong expression of Cdx genes normally is found in the intestine but not in the esophagus and stomach. When mice are genetically engineered so that their gastric cells express Cdx, the stomach develops a metaplastic, intestinal-type epithelium similar to that of Barrett's esophagus. Exposure to acid and bile has been shown to activate the Cdx promoter in certain esophageal cell lines, and Cdx expression has been found in inflamed esophageal squamous epithelium and in the specialized intestinal metaplasia of Barrett's esophagus. Barrett's metaplasia must be sustained by stem cells, which might be identified by putative, intestinal stem cell markers like leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) and doublecortin and CaM kinase-like-1 (DCAMKL-1). Emerging concepts in tumor biology suggest that Barrett's cancers may develop from growth-promoting mutations in metaplastic stem cells or their progenitor cell progeny. This report reviews the roles of developmental signaling pathways and the Cdx genes in the development of normal gut epithelia and the potential mechanisms whereby GERD may induce the esophageal expression of Cdx genes and other morphogenetic factors that mediate the development of Barrett's metaplasia. The role of stem cells in the development of metaplasia and in carcinogenesis and the potential for therapies directed at those stem cells also is addressed.     

Deoxycholic acid causes DNA damage while inducing apoptotic resistance through NF-κB activation in benign Barrett's epithelial cells

Gastroesophageal reflux is associated with adenocarcinoma in Barrett's esophagus, but the incidence of this tumor is rising, despite widespread use of acid-suppressing medications. This suggests that refluxed material other than acid might contribute to carcinogenesis. We looked for potentially carcinogenetic effects of two bile acids, deoxycholic acid (DCA) and ursodeoxycholic acid (UDCA), on Barrett's epithelial cells in vitro and in vivo. We exposed Barrett's (BAR-T) cells to DCA or UDCA and studied the generation of reactive oxygen/nitrogen species (ROS/RNS); expression of phosphorylated H2AX (a marker of DNA damage), phosphorylated IkBα, and phosphorylated p65 (activated NF-κB pathway proteins); and apoptosis. During endoscopy in patients, we took biopsy specimens of Barrett's mucosa before and after esophageal perfusion with DCA or UDCA and assessed DNA damage and NF-κB activation. Exposure to DCA, but not UDCA, resulted in ROS/RNS production, DNA damage, and NF-κB activation but did not increase the rate of apoptosis in BAR-T cells. Pretreatment with N-acetyl-l-cysteine (a ROS scavenger) prevented DNA damage after DCA exposure, and DCA did induce apoptosis in cells treated with NF-κB inhibitors (BAY 11-7085 or AdIκB superrepressor). DNA damage and NF-κB activation were detected in biopsy specimens of Barrett's mucosa taken after esophageal perfusion with DCA, but not UDCA. These data show that, in Barrett's epithelial cells, DCA induces ROS/RNS production, which causes genotoxic injury, and simultaneously induces activation of the NF-κB pathway, which enables cells with DNA damage to resist apoptosis. We have demonstrated molecular mechanisms whereby bile reflux might contribute to carcinogenesis in Barrett's esophagus.     

Differences in activity and phosphorylation of MAPK enzymes in esophageal squamous cells of GERD patients with and without Barrett's esophagus

We hypothesized that, in esophageal squamous epithelial cells, there are differences among individuals in the signal transduction pathways activated by acid reflux that might underlie the development of Barrett's esophagus. To explore that hypothesis, we immortalized nonneoplastic, esophageal squamous cells from patients with gastroesophageal reflux disease (GERD) with (NES-B3T) and without (NES-G2T) Barrett's esophagus and used those cells to study acid effects on MAPK proteins. During endoscopy in patients with GERD with and without Barrett's esophagus, we took biopsy specimens from the distal squamous esophagus to study MAPK proteins before and after esophageal perfusion with 0.1 N HCl. We used immunoblotting and Western blotting to study MEK1/2 phosphorylation at two activating sites (serines 217/221), MEK1 phosphorylation at an inhibitory site (threonine 286), and MEK1/2 activity. After acid exposure, both cell lines exhibited increased MEK1/2 phosphorylation at the activating sites; the NES-B3T cells had higher levels of MEK1 phosphorylation at the inhibitory site, however, and only the NES-G2T cells showed an acid-induced increase in MEK1/2 activity. Similarly, in the squamous epithelium of patients with GERD with and without Barrett's esophagus, acid perfusion increased MEK1/2 phosphorylation at the activating sites in both patient groups; the Barrett's patients had higher levels of MEK1 phosphorylation at the inhibitory site, however, and only the patients without Barrett's demonstrated an acid-induced increase in ERK1/2 phosphorylation. In esophageal squamous cell lines and biopsies from patients with GERD with and without Barrett's esophagus, we have found differences in MAPK pathways activated by acid exposure. We speculate that these differences might underlie the development of Barrett's metaplasia.     

The decreased expression of Beclin-1 correlates with progression to esophageal adenocarcinoma: the role of deoxycholic acid

Beclin-1 has a central role in the regulation of autophagy. Barrett's esophagus (BE) is associated with a significantly increased risk for the development of esophageal adenocarcinoma (EAC). In the current study, we evaluated the role of Beclin-1 and autophagy in the EAC. Biopsies obtained from patients with BE and EAC, tissues from a rat model of BE and EAC, and esophageal cell lines were evaluated for the expression of Beclin-1 by immunohistochemistry, immunoblotting, or RT-PCR. Since reflux of bile acids is important in EAC, we also evaluated the effect of exposure to deoxycholic acid (DCA) on autophagy and Beclin-1 expression. Beclin-1 expression was high in squamous epithelium and nondysplastic BE, whereas its expression was low in dysplastic BE and EAC. The same pattern of expression was observed in rat tissues and in esophageal cell lines. Normal esophageal epithelium and HET-1A cells (derived from normal squamous epithelium) show high levels of Beclin-1, but lower levels of Beclin-1 were found in BE and EAC cell lines (CP-A, CP-C, and OE33). Acute exposure to DCA led to increased Beclin-1 expression and increased autophagy as evaluated by electron microscopy and counting percentage of GFP-LC3-positive BE cells with punctate pattern. In contrast, chronic exposure to DCA did not result in the alteration of Beclin-1 levels or autophagy. In summary, these data suggest that autophagy is initially activated in response to bile acids, but chronic exposure to bile acids leads to decreased Beclin-1 expression and autophagy resistance.     

Mechanisms of oxidant production in esophageal squamous cell and Barrett's cell lines

We hypothesized that differences among individuals in reflux-induced oxidant production by esophageal squamous epithelial cells might contribute to the development of Barrett's esophagus. We studied the effects of acid and bile acids on the production of reactive oxygen species (ROS) in esophageal squamous cell lines derived from gastroesophageal reflux disease patients with (NES-B3T) and without (NES-G2T) Barrett's esophagus and in a Barrett's epithelial cell line (BAR-T). Cells were incubated with an ROS-sensitive probe and exposed to acidic medium, neutral bile acid medium, or acidic bile acid medium. ROS were quantified in the presence and absence of diphenyleneiodonium chloride (DPI, an NADPH oxidase inhibitor), N(G)-monomethyl-l-arginine (l-NMMA, a nitric oxide synthase inhibitor), and rotenone (a mitochondrial electron transport chain inhibitor). Acidic bile acid medium induced ROS production in both squamous cell lines; however, only DPI blocked ROS production by NES-B3T cells, whereas both DPI and l-NMMA blocked ROS production by NES-G2T cells. In BAR-T cells, acidic medium and acidic bile acid medium induced the production of ROS; l-NMMA prevented ROS production after exposure to acidic medium, whereas ROS production induced by acidic bile acid medium was blocked by DPI. These studies demonstrate that there are differences between esophageal squamous cells and Barrett's epithelial cells and between esophageal squamous cells from gastroesophageal reflux disease patients with and without Barrett's esophagus in the mechanisms of oxidant production induced by exposure to acid and bile acids.     

Downregulation of p63 upon exposure to bile salts and acid in normal and cancer esophageal cells in culture

p63 is a member of the p53 protein family that regulates differentiation and morphogenesis in epithelial tissues and is required for the formation of squamous epithelia. Barrett's mucosa is a glandular metaplasia of the squamous epithelium that develops in the lower esophagus in the context of chronic, gastroesophageal reflux and is considered as a precursor for adenocarcinoma. Normal or squamous cancer esophageal cells were exposed to deoxycholic acid (DCA, 50, 100, or 200 microM) and chenodeoxycholic and taurochenodeoxycholic acid at pH 5. p63 and cyclooxygenase-2 (COX-2) expressions were studied by Western blot and RT-PCR. DCA exposure at pH 5 led to a spectacular decrease in the levels of all isoforms of the p63 proteins. This decrease was observed within minutes of exposure, with a synergistic effect between DCA and acid. Within the same time frame, levels of p63 mRNA were relatively unaffected, whereas levels of COX-2, a marker of stress responses often induced in Barrett's mucosa, were increased. Similar results were obtained with chenodeoxycholic acid but not its taurine conjugate at pH 5. Proteasome inhibition by lactacystin or MG-132 partially blocked the decrease in p63, suggesting a posttranslational degradation mechanism. These results show that combined exposure to bile salt and acid downregulates a critical regulator of squamous differentiation, providing a mechanism to explain the replacement of squamous epithelium by a glandular metaplasia upon exposure of the lower esophagus to gastric reflux.     

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.     

Production of prostaglandinE2 via bile acid is enhanced by trypsin and acid in normal human esophageal epithelial cells

Several reports suggest that duodenogastroesophageal reflux may produce esophagitis, Barrett's esophagus and esophageal carcinoma. And it is well known that the incidence of adenocarcinoma arising from Barrett's esophagus has been increasing during the past decade. On the other hand, cyclooxygenase-2 and prostaglandins, produced by the catalytic reaction of cyclooxygenase-2, are considered to relate to carcinogenesis of the digestive tract and other malignant tumors. Recent reports suggest that cyclooxygenase-2 is induced in Barrett's esophagus and esophageal carcinoma. The purpose of this study is to investigate the reaction of cyclooxygenase-2 expression and prostaglandinE2 production on normal human esophageal epithelial cells cultured with gastroduodenal components. Normal human esophageal epithelial cells were cultured with chenodeoxycholic acid, trypsin and in acidic condition, individually and with different combinations of these three factors. After culturing, cyclooxygenase-2 expression in the cells and amount of prostglandinE2 in culture media was evaluated by immunoblotting and enzyme-immunoassay, respectively after culturing the cells. Cyclooxygenase-2 expression was up-regulated by bile acid and prostaglandinE2 production was enhanced by bile acid with trypsin, acidic condition or both of these components, without a synergistic effect on cyclooxygenase-2 expression. Production of prostaglandinE2 via these factors was suppressed by the cyclooxygenase-2 selective inhibitor JTE-522.The results suggest that duodenogastroesophageal reflux may induce cyclooxygenase-2 expression and prostaglandinE2 production in esophageal epithelial cells, cyclooxygenase-2 specific inhibitors may have a chemopreventive effect on esophageal carcinoma.     

Reduction of E-cadherin by human defensin-5 in esophageal squamous cells

Barrett’s esophagus (BE) is metaplastic columnar epithelium converted from normal squamous epithelia in the distal esophagus that is thought to be a precancerous lesion of esophageal adenocarcinoma. BE is attributed to gastroesophageal reflux disease (GERD), and therefore gastric acid or bile acids are thought to be factors that cause epithelial cell damage and inflammation in the gastro-esophageal junction. The decrease of adherent junction molecules, E-cadherin has been reported to be associated with the progression of the Barrett’s carcinoma, but the initiation of BE is not sufficiently understood. BE is characterized by the presence of goblet cells and occasionally Paneth cells are observed at the base of the crypts. The Paneth cells possess dense granules, in which human antimicrobial peptide human defensin-5 (HD-5) are stored and secreted out of the cells. This study determined the roles of HD-5 produced from metaplastic Paneth cells against adjacent to squamous cells in the gastro-esophageal junction. A human squamous cell line Het-1A, was incubated with the synthetic HD-5 peptide as a model of squamous cell in the gastro-esophageal junctions, and alterations of E-cadherin were investigated. Immunocytochemistry, flowcytometry, and Western blotting showed that the expression of E-cadherin protein was decreased. And a partial recovery from the decrease was observed by treatment with a CD10/neprilysin inhibitor (thiorphan). In conclusion, E-cadherin expression in squamous cells was reduced by HD-5 using in vitro experiments. In gastro-esophageal junction, HD-5 produced from metaplastic Paneth cells may therefore accelerate the initiation of BE.     

Immunohistochemical evaluation of pRb2/p130, VEGF, EZH2, p53, p16, p21waf-1, p27, and PCNA in Barrett's esophagus

Control of the G1/S-phase transition as well as angiogenic switch are two of the most studied mechanisms in cancer. The current study examined the correlation between the immunohistochemical expression of pRb2/p130, VEGF, EZH2, p53, p16, p21waf-1, p27, and PCNA in Barrett's esophagus (BE). Overall, p53 showed a much higher expression in BE patients (up to 50%) than in controls (1-10%) (P < 0.005). Also p21 showed a downregulation in BE when compared to normal esophagus (70% of cells vs. 65%), but the difference did not show any statistical significance (P = 0.45). pRb2/p130 was detected in 80% of cells in normal controls, but showed positive in only 20% of cells in BE biopsies. Additionally, Rb2/p130 expression was inversely correlated to that of VEGF, EZH2, and PCNA (P < 0.0001, P = 0.0032, P < 0.001, respectively). p27 stained more intensely and in a widespread manner (70%) cells in normal esophageal tissues but about only 30% in BE samples (P < 0.001). Lastly, in accordance with other reports, we also found p16 expressed by immunohistochemistry at high levels in normal controls and at low levels in BE (P < 0.001). In conclusion, p16, p21, p27, and p53 staining confirmed previously published data. Interestingly, pRb2/p130 expression was found significantly decreased in metaplastic epithelium compared to normal controls and showed significant inverse correlation with the expression of other markers, such as VEGF, EZH2, and PCNA. These data, taken together, indicate that these molecular events occurring in Barrett's metaplasia (BM) may represent one of the many steps taking place during esophageal malignant progression such as impairment of cell-cycle control, altered differentiation, and unbalanced angiogenesis.     

All trans-retinoic acid induces apoptosis via p38 and caspase pathways in metaplastic Barrett's cells

Retinoids such as all trans-retinoic acid (ATRA) have been used as chemopreventive agents for a number of premalignant conditions. To explore a potential role for retinoids as chemopreventive agents for Barrett's esophagus, we studied ATRA's effects on apoptosis in a nonneoplastic, telomerase-immortalized, metaplastic Barrett's cell line. We treated the Barrett's cells with ATRA in the presence and absence of inhibitors to p53 (pSRZ-siRNA-p53), p38 (SB-203580 and p38 siRNA), and the caspase cascade (z-Val-Ala-Asp-fluoromethyl ketone). We determined the effects of ATRA and the various inhibitors on apoptosis using cell morphology, terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling staining, cleaved caspase-3 immunofluorescence, and Annexin V staining. We also determined how ATRA in the presence and absence of the inhibitors affected apoptosis following low-dose UV-B irradiation. ATRA induced apoptosis and increased the expression of p53 protein in a dose-dependent fashion. The apoptotic effect of ATRA was abolished by treatment with inhibitors of both p38 and caspase, but not by p53 interfering RNA (RNAi). Inhibition of p38 also prevented expression of cleaved caspase-3, suggesting that ATRA activates p38 upstream of the caspase cascade. We found that ATRA sensitized immortalized Barrett's cells to apoptosis induced by low-dose UV-B irradiation via a similar mechanism. ATRA induces apoptosis in Barrett's epithelial cells and sensitizes them to apoptosis induced by UV-B irradiation via activation of p38 and the caspase cascade, but not through p53. This study elucidates molecular pathways whereby retinoid treatment might prevent carcinogenesis in Barrett's metaplasia and suggests a potential role for the use of safer retinoids for chemoprevention in Barrett's esophagus.     

GERD is associated with shortened telomeres in the squamous epithelium of the distal esophagus

Telomeres are repetitive DNA sequences located at the ends of chromosomes. Telomeres are shortened by repeated cell divisions and by oxidative DNA damage, and cells with critically shortened telomeres cannot divide. We hypothesized that chronic gastroesophageal reflux disease (GERD)-induced injury of the esophageal squamous epithelium results in progressive telomeric shortening that eventually might interfere with mucosal healing. To address our hypothesis, we compared telomere length and telomerase activity in biopsy specimens of esophageal squamous epithelium from GERD patients and control patients. Endoscopic biopsies were taken from the esophageal squamous epithelium of 38 patients with GERD [10 long-segment Barrett's esophagus (LSBE), 15 short-segment (SSBE), 13 GERD without Barrett's esophagus] and 16 control patients without GERD. Telomere length was assessed using the terminal restriction fragment assay, and telomerase activity was studied by the PCR-based telomeric repeat amplification protocol assay. Patients with GERD had significantly shorter telomeres in the distal esophagus than controls [8.3 +/- 0.5 vs. 10.9 +/- 1.5 (SE) Kbp, P = 0.043]. Among the patients with GERD, telomere length in the distal esophagus did not differ significantly in those with and without Barrett's esophagus (LSBE 7.9 +/- 0.8, SSBE 8.6 +/- 0.9, GERD without BE 8.7 +/- 1.0 Kbp). No significant differences in telomerase activity in the distal esophagus were noted between patients with GERD and controls (4.0 +/- 0.39 vs. 5.2 +/- 0.53 RIUs). Telomeres in the squamous epithelium of the distal esophagus of patients who have GERD, with and without Barrett's esophagus, are significantly shorter than those of patients without GERD despite similar levels of telomerase activity.     

Development and characterization of an organotypic model of Barrett's esophagus

Understanding the molecular and cellular processes underlying the development, maintenance, and progression of Barrett's esophagus (BE) presents an empirical challenge because there are no simple animal models and standard 2D cell culture can distort cellular processes. Here we describe a three-dimensional (3D) cell culture system to study BE. BE cell lines (CP-A, CP-B, CP-C, and CP-D) and esophageal squamous keratinocytes (EPC2) were cultured on a matrix consisting of esophageal fibroblasts and collagen. Comparison of growth and cytokeratin expression in the presence of all-trans retinoic acid or hydrochloric acid was made by immunohistochemistry and Alcian Blue staining to determine which treatments produced a BE phenotype of columnar cytokeratin expression in 3D culture. All-trans retinoic acid differentially affected the growth of BE cell lines in 3D culture. Notably, the non-dyplastic metaplasia-derived cell line (CP-A) expressed reduced squamous cytokeratins and enhanced columnar cytokeratins upon ATRA treatment. ATRA altered the EPC2 squamous cytokeratin profile towards a more columnar expression pattern. Cell lines derived from patients with high-grade dysplasia already expressed columnar cytokeratins and therefore did not show a systematic shift toward a more columnar phenotype with ATRA treatment. ATRA treatment, however, did reduce the squamoid-like multilayer stratification observed in all cell lines. As the first study to demonstrate long-term 3D growth of BE cell lines, we have determined that BE cells can be cultured for at least 3 weeks on a fibroblast/collagen matrix and that the use of ATRA causes a general reduction in squamous-like multilayered growth and an increase in columnar phenotype with the specific effects cell-line dependent.     

Immunohistochemical demonstration of IgA and secretory component in relation to epithelial cell differentiation in normal colorectal mucosa and metaplastic polyp: a semiquantitative study

Summary The metaplastic polyp is a non-neoplastic epithelial lesion found within the human colorectum. Although not regarded as precancerous, recent studies have demonstrated the expression of multiple cancerassociated phenotypes. This might indicate a possible indirect relationship between metaplastic polyps and colorectal cancer. Epithelial secretory component and IgA were demonstrated by the immunoperoxidase technique and staining intensities were assessed semiquantitatively. The findings were related to cellular differentiation in normal colorectal epithelium as compared to the metaplastic polyp. The crypt base cells and also the surface epithelial cells stained with similar intensity in both types of epithelium. However, the expected increase in staining characterizing normal lower and upper crypt columnar cells and reduction in staining associated with the switch from crypt to surface columnar cell was not observed in the metaplastic polyp. Metaplastic crypt columnar cells showed significantly reduced staining for both IgA and secretory component as compared to their normal counterparts. There was also a significant reduction in the number of IgA-secreting plasma cells in the lamina propria of the metaplastic polyp. These findings are consistent with the concept of a premature switch to mature surface cell characteristics within the metaplastic polyp. They are discussed in the light of other changes in phenotype associated with this lesion.     

p53 and the malignant progression of Barrett's esophagus

Barrett's esophagus (BE) is a metaplastic disorder in which specialized columnar epithelium replaces healthy squamous epithelium (intestinal metaplasia). Even though its pathophysiology and the steps of its neoplastic progression are not completely understood, BE can be considered as a complication of gastroesophageal reflux disease (GERD). Given that esophageal adenocarcinoma, which is continually increasing in the Western world, still has a poor prognosis and suffers from late diagnosis, and because BE is a precancerous lesion, there is a strong need for good molecular markers of malignant progression in Barrett's metaplasia (BM). The aim of this review is to examine the published data regarding the role that assessment of p53 may play in the management of BE, trying to understand if it may be a useful marker to early diagnose BE malignant transformation.     

CCN1 is critical for acid-induced esophageal epithelial cell transformation

CCN1 is a matricellular protein involved in both wound healing and cancer cell invasion. Increased CCN1 expression has been associated with the development of Barrett’s esophagus and the increased risk of progression to esophageal adenocarcinoma. In both cases, acid reflux is a major contributor. Low pH has been shown to induce CCN1 gene expression in esophageal epithelial cells. Here we demonstrated that both CCN1 and low pH could cause esophageal epithelial cell transformation, including loss of E-cadherin, disruption of cell-cell junctions, and expression of mesenchymal markers. Furthermore, knockdown of CCN1 through RNA interference sufficiently attenuated acid-driven cell phenotypic changes, while over-expression of CCN1 exacerbated these effects, indicating a critical role of CCN1 in acid-induced esophageal epithelial cell transformation. Given the pivotal role of low pH in gastro-esophageal reflux disease and its progression towards esophageal adenocarcinoma, our study identified CCN1 as a key molecule mediating this process.