Oxidative damage in an esophageal adenocarcinoma model with rats

Atractylenolide III ameliorated reflux esophagitis via PI3K/AKT/NF-κB/iNOS pathway in rats

Reflux esophagitis (RE), an esophageal inflammation caused by reflux of gastric contents, often damages the lower esophagus, seriously affecting the quality of life of patients. This study aims to investigate the therapeutic effects and underlying molecular mechanisms of atractylenolide III (ATL III) on RE model rats. In this research, the RE rat model is established sequentially following hemipyloric ligation, cardia transection, and hydrochloric acid perfusion. Further, the RE-induced rats are intragastrically administrated with ATL III (0.6, 1.2, and 2.4 mg/kg/D) for 28 days to evaluate ATL III therapeutic effects. To study the molecular mechanism, RE rats are treated with a phosphoinositide-3 kinase (PI3K) agonist (740 Y-P) combined with ATL III. The histopathological changes in the esophagus are eventually observed by hematoxylin & eosin (H&E) staining. In addition to changes in gastric pH and levels of reactive oxygen species (ROS), enzyme-linked immunosorbent assay (ELISA) and Western blot analyses are used to detect the expression levels of tumor necrosis factor-α (TNF-α, mmol/L), interleukin (IL)-8, IL-6, IL-1β in the esophageal tissues. As a result, the lesions in the esophageal tissues of RE rats are alleviated, decreasing the macroscopic observation scores of the esophageal mucosa after ATL III treatment,. The experimental results indicated significantly increased pH value of the gastric contents and reduced ROS, thiobarbituric acid reactants (TBARS), TNF-α, IL-8, IL-6, and IL-1β levels, as well as expression levels of p-PI3K, p-AKT, iNOS, and nuclear NF-κB proteins in esophageal tissues. In conclusion, the study indicated that ATL III could efficiently treat RE in rats by inhibiting oxidative stress and inflammatory damage through the PI3K/AKT/NF-κB/iNOS pathway.

The progress in the relationship between trace elements and acute lymphoblastic leukemia

Trace elements are very important substances with low content in the human body. If the content of some trace elements changes, they are also related to diseases. Acute lymphoblastic leukemia (ALL) is a malignant blood tumor, and its relationship with trace elements has also been a concern by scholars. Not only have the trace element levels in ALL patients changed, but the efficacy of different treatment methods has also been linked to the corresponding trace element changes. The characteristics of ALL may be related to the dysregulation of differentiation and proliferation of lymphoid precursor cells. Cell proliferation and differentiation are often affected by changes in DNA levels. However, trace elements are involved in DNA damage and repair mechanisms. In recent years, as an increasing number of studies believe that ALL is related to the abnormal metabolism of trace elements in the body, this paper intends to discuss the research progress on the relationship between trace elements and ALL to provide more information on trace elements for the diagnosis, treatment, and prevention of ALL.

Pharmacological Mechanism of Zuojin Pill for Gastroesophageal Reflux Disease: A Network Pharmacology Study

Background. Although Zuojin Pill (ZJP) is widely used in China as a traditional prescription to treat gastroesophageal reflux disease (GERD), its exact mechanism of action is still unknown. Therefore, we employed network pharmacology (NP), molecular docking (MD), and molecular dynamics simulation (MDS) to investigate the pharmacological mechanisms of ZJP against GERD. Methods. Active compounds and target genes corresponding to ZJP and target genes related to GERD were identified through analysis of publicly available datasets. Subsequently, the obtained data were subjected to further network pharmacological analysis to explore the potential key active compounds, core target genes, and biological processes (BPs) associated with the effect of ZJP against GERD. Finally, the prediction results of NP were validated by MD, and MDS of the optimal core protein-ligand for each component obtained by MD were performed using Gromacs 2020 software. Results. Twelve active components of ZJP were identified to act on 82 target genes associated with GERD, and ZJP might exert an anti-GERD effect through the regulation of BPs such as reactive oxygen species (ROS) metabolism, response to oxidative stress (OS), and ROS, as well as the activation of signaling pathways such as apoptosis, p53 signaling, chemical carcinogenesis-ROS, and HIF-1 signaling pathways. Furthermore, quercetin, kaempferol, and coptisine, the three key components of ZJP were shown to stably bond with the 14 core target genes, including AKT1, MMP2, TP53, EGFR, JUN, CASP3, CXCL8, HIF1α, IL-1β, MYC, PPARG, MMP9, PTGS2, and FOS. Results from MDS showed that PPARG-quercetin and MMP2-quercetin bound more stably. Conclusions. The findings suggest that ZJP alleviates the symptoms of GERD and improves the prognosis by regulating ROS metabolism, thereby reducing the secretion of proinflammatory cytokines like IL-1β, COX-2, CXCL8, and MMPs, regulating the expression of oncogenes such as JUN and FOS, and maintaining the normal expression of tumor suppressor genes such as TP53 and MYC. However, whether the effect of this modulation of ROS metabolism is positive or negative needs to be further verified by pharmacological experiments.

Pilot Study Showing Feasibility of Phosphoproteomic Profiling of Pathway-Level Molecular Alterations in Barrett’s Esophagus

(1) Background: Barrett’s esophagus is a major risk factor for esophageal adenocarcinoma. In this pilot study, we employed precision mass spectrometry to map global (phospho)protein perturbations in Barrett’s esophagus lesions and adjacent normal tissue to glean insights into disease progression. (2) Methods: Biopsies were collected from two small but independent cohorts. Comparative analyses were performed between Barrett’s esophagus samples and adjacent matched (normal) tissues from patients with known pathology, while specimens from healthy patients served as additional controls. (3) Results: We identified and quantified 6810 proteins and 6395 phosphosites in the discovery cohort, revealing hundreds of statistically significant differences in protein abundances and phosphorylation states. We identified a robust proteomic signature that accurately classified the disease status of samples from the independent patient cohorts. Pathway-level analysis of the phosphoproteomic profiles revealed the dysregulation of specific cellular processes, including DNA repair, in Barrett’s esophagus relative to paired controls. Comparative analysis with previously published transcriptomic profiles provided independent evidence in support of these preliminary findings. (4) Conclusions: This pilot study establishes the feasibility of using unbiased quantitative phosphoproteomics to identify molecular perturbations associated with disease progression in Barrett’s esophagus to define potentially clinically actionable targets warranting further assessment.

Mutperiod: Analysis of periodic mutation rates in nucleosomes

Nucleosomes modulate DNA damage and repair, resulting in periodic mutation rates in nucleosomal DNA. Previous research has characterized these patterns in many sequenced tumor genomes; however, computational tools to identify and quantify these periodicities have not been developed for the broader scientific community. Here, we describe mutperiod, a Python and R based toolset that quantifies nucleosome mutational periodicities and compares them across different genetic and cellular backgrounds. We use mutperiod to demonstrate that DNA mismatch repair contributes to the nucleosome mutational periodicity observed in esophageal adenocarcinomas, and that the strength of this mutational periodicity varies in different chromatin states.

Reactivation of the Hedgehog pathway in esophageal progenitors turns on an embryonic-like program to initiate columnar metaplasia

Columnar metaplasia of the esophagus is the main risk factor for esophageal adenocarcinoma. There is a lack of evidence to demonstrate that esophageal progenitors can be the source of columnar metaplasia. In this study, using transgenic mouse models, lineage tracing, single-cell RNA sequencing, and transcriptomic and epigenetic profiling, we found that the activation of the Hedgehog pathway in esophageal cells modifies their differentiation status in vivo. This process involves an initial step of dedifferentiation into embryonic-like esophageal progenitors. Moreover, a subset of these cells undergoes full squamous-to-columnar conversion and expresses selected intestinal markers. These modifications of cell fate are associated with remodeling of the chromatin and the appearance of Sox9. Using a conditional knockout mouse, we show that Sox9 is required for columnar conversion but not for the step of dedifferentiation. These results provide insight into the mechanisms by which esophageal cells might initiate columnar metaplasia.

Inflammation-Related Carcinogenesis: Lessons from Animal Models to Clinical Aspects

Simple Summary

In multicellular organisms, inflammation is the body’s most primitive and essential protective response against any external agent. Inflammation, however, not only causes various modern diseases such as cardiovascular disorders, neurological disorders, autoimmune diseases, metabolic syndrome, infectious diseases, and cancer but also shortens the healthy life expectancy. This review focuses on the onset of carcinogenesis due to chronic inflammation caused by pathogen infections and inhalation/ingestion of foreign substances. This study summarizes animal models associated with inflammation-related carcinogenesis by organ. By determining factors common to inflammatory carcinogenesis models, we examined strategies for the prevention and treatment of inflammatory carcinogenesis in humans.

Abstract

Inflammation-related carcinogenesis has long been known as one of the carcinogenesis patterns in humans. Common carcinogenic factors are inflammation caused by infection with pathogens or the uptake of foreign substances from the environment into the body. Inflammation-related carcinogenesis as a cause for cancer-related death worldwide accounts for approximately 20%, and the incidence varies widely by continent, country, and even region of the country and can be affected by economic status or development. Many novel approaches are currently available concerning the development of animal models to elucidate inflammation-related carcinogenesis. By learning from the oldest to the latest animal models for each organ, we sought to uncover the essential common causes of inflammation-related carcinogenesis. This review confirmed that a common etiology of organ-specific animal models that mimic human inflammation-related carcinogenesis is prolonged exudation of inflammatory cells. Genotoxicity or epigenetic modifications by inflammatory cells resulted in gene mutations or altered gene expression, respectively. Inflammatory cytokines/growth factors released from inflammatory cells promote cell proliferation and repair tissue injury, and inflammation serves as a “carcinogenic niche”, because these fundamental biological events are common to all types of carcinogenesis, not just inflammation-related carcinogenesis. Since clinical strategies are needed to prevent carcinogenesis, we propose the therapeutic apheresis of inflammatory cells as a means of eliminating fundamental cause of inflammation-related carcinogenesis.

Differential Expression Profiles of Oxidative Stress Levels, 8-oxo-dG and 4-HNE, in Barrett's Esophagus Compared to Esophageal Adenocarcinoma

Barrett’s esophagus (BE), a chronic inflammatory condition, is the leading risk factor for esophageal adenocarcinoma (EAC). In inflammation to cancer pathways, oxidative stress profiles have been linked to cancer progression. However, the relevance of oxidative stress profiles along the BE-disease sequence remains to be elucidated. In this study, markers of oxidative stress; DNA adducts (8-oxo-dG) and lipoperoxidation (4-HNE), and markers of proliferation (Ki67) were measured in patient biopsies representing the BE-disease sequence. Differences in expression of these markers in Barrett’s patients with cancer-progression and non-progression were examined. Proliferation was reduced in Barrett’s specialized intestinal metaplasia (SIM) compared with EAC (p < 0.035). Correcting for cell proliferation levels, a confounding factor, linked to oxidative stress profiles, SIM demonstrated increased levels of 8-oxo-dG and 4-HNE (p < 0.05) compared with EAC. Longitudinal analysis of Barrett’s patients demonstrated decreased levels of 8-oxo-dG in SIM cancer progression (p < 0.05). BE is an environment of increased oxidative stress and inflammation. Patients with progressive disease demonstrated reduced oxidative stress levels in 8-oxo-dG. Perhaps these alterations facilitate Barrett’s progression, whereas in non-progressive disease, cells follow the rules of increased oxidative stress ultimately triggers cell apoptosis, thereby preventing propagation and survival.

From genetics to signaling pathways: molecular pathogenesis of esophageal adenocarcinoma

Esophageal adenocarcinoma (EAC) has one of the fastest rising incidence rates in the U.S. and many other Western countries. One of the unique risk factors for EAC is gastroesophageal reflux disease (GERD), a chronic digestive condition in which acidic contents from the stomach, frequently mixed with duodenal bile, enter the esophagus resulting in esophageal tissue injury. At the cellular level, progression to EAC is underlined by continuous DNA damage caused by reflux and chronic inflammatory factors that increase the mutation rate and promote genomic instability. Despite recent successes in cancer diagnostics and treatment, EAC remains a poorly treatable disease. Recent research has shed new light on molecular alterations underlying progression to EAC and revealed novel treatment options. This review focuses on the genetic and molecular studies of EAC. The molecular changes that occur during the transformation of normal Barrett's esophagus to esophageal adenocarcinoma are also discussed.

Miniaturized omnidirectional flexible side-view endoscope for rapid monitoring of thin tubular biostructures

Endoscopic imaging allows longitudinal observation of epithelial pathologies in tubular organs throughout the body. However, the imaging and optical diagnosis of tubular biostructures such as small animal models and small pediatric organs require appropriately miniaturized devices. A miniaturized catadioptric flexible side-view endoscope is proposed with omnidirectional field of view (FOV) in the transverse direction and sub-mm-scale feature resolution. The FOV in the longitudinal direction is 50°. Images are unwrapped and stitched together to form composite images of the target by two different algorithms, revealing a composite FOV of more than 3.5 cm × 360°. The endoscope is well suited for minimally invasive rapid monitoring of thin tubular organs in pediatric patients, as well as for imaging of small animal disease models at near-cellular resolution.

Protective effects of Artemisia campestris extract against gastric acid reflux-induced esophageal mucosa injuries

Artemisia campestris L. has been widely used in alternative medicine to treat digestive system diseases, particularly gastroesophageal disorders. In the present investigation, we studied the putative protective effect of Artemisia campestris aqueous extract (ACAE) against gastro-esophageal reflux (GER)-induced esophagitis in rats. The experimental ophagitis was induced by the ligation of the pylorus as well as the junction between the forestomach and the corpus. We firstly found that ACAE administration at 100, 200 and 400 mg/kg, b.w., p.o. significantly protected GER-induced macroscopic and histological injuries in the esophagus tissue. Our extract also counteracted GER-induced esophagus lipoperoxidation, restored the depletion of antioxidant enzyme activities such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) as well as thiol groups levels. Furthermore, we showed that acute GER provoked an increase in esophagus mucosa hydrogen peroxide (H₂O₂), free iron and calcium levels, whereas ACAE treatment reversed all GER-induced intracellular mediators' disturbances. In conclusion, we suggested that ACAE had potent protective effects against esophagitis due, in part, to its antioxidant properties as well as its opposite effect on some intracellular mediators.

Metaplasia: tissue injury adaptation and a precursor to the dysplasia-cancer sequence

Metaplasia is the replacement of one differentiated somatic cell type with another differentiated somatic cell type in the same tissue. Typically, metaplasia is triggered by environmental stimuli, which may act in concert with the deleterious effects of microorganisms and inflammation. The cell of origin for intestinal metaplasia in the oesophagus and stomach and for pancreatic acinar-ductal metaplasia has been posited through genetic mouse models and lineage tracing but has not been identified in other types of metaplasia, such as squamous metaplasia. A hallmark of metaplasia is a change in cellular identity, and this process can be regulated by transcription factors that initiate and/or maintain cellular identity, perhaps in concert with epigenetic reprogramming. Universally, metaplasia is a precursor to low-grade dysplasia, which can culminate in high-grade dysplasia and carcinoma. Improved clinical screening for and surveillance of metaplasia might lead to better prevention or early detection of dysplasia and cancer.

Modeling Esophagitis Using Human Three-Dimensional Organotypic Culture System

Esophagitis, whether caused by acid reflux, allergic responses, graft-versus-host disease, drugs, or infections, is a common condition of the gastrointestinal tract affecting nearly 20% of the US population. The instigating agent typically triggers an inflammatory response. The resulting inflammation is a risk factor for the development of esophageal strictures, Barrett esophagus, and esophageal adenocarcinoma. Research into the pathophysiology of these conditions has been limited by the availability of animal and human model systems. Three-dimensional organotypic tissue culture (OTC) is an innovative three-dimensional multicellular in vitro platform that recapitulates normal esophageal epithelial stratification and differentiation. We hypothesized that this platform can be used to model esophagitis to better understand the interactions between immune cells and the esophageal epithelium. We found that human immune cells remain viable and respond to cytokines when cultured under OTC conditions. The acute inflammatory environment induced in the OTC significantly affected the overlying epithelium, inducing a regenerative response marked by increased cell proliferation and epithelial hyperplasia. Moreover, oxidative stress from the acute inflammation induced DNA damage and strand breaks in epithelial cells, which could be reversed by antioxidant treatment. These findings support the importance of immune cell-mediated esophageal injury in esophagitis and confirms the utility of the OTC platform to characterize the underlying molecular events in esophagitis.

Autophagy levels are elevated in barrett's esophagus and promote cell survival from acid and oxidative stress

Autophagy is a highly conserved mechanism that is activated during cellular stress. We hypothesized that autophagy may be induced by acid reflux, which causes injury, and inflammation, and therefore, contributes to the pathogenesis of Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC). Currently, the role of autophagy in BE and EAC is poorly studied. We quantitatively define autophagy levels in human BE cell lines, a transgenic mouse model of BE, and human BE, and EAC biopsies. Human non-dysplastic BE had the highest basal number of autophagic vesicles (AVs), while AVs were reduced in normal squamous cells and dysplastic BE cells, and nearly absent in EAC. To demonstrate a functional role for autophagy in BE pathogenesis, normal squamous (STR), non-dysplastic BE (CPA), dysplastic BE (CPD), and EAC (OE19) cell lines were exposed to an acid pulse (pH 3.5) followed by incubation in the presence or absence of chloroquine, an autophagy inhibitor. Acid exposure increased reactive oxygen species (ROS) levels in STR and CPA cells. Chloroquine alone had a small impact on intracellular ROS or cell survival. However, combination of chloroquine with the acid pulse resulted in a significant increase in ROS levels at 6 h in STR and CPA cells, and increased cell death in all cell lines. These findings establish increased numbers of AVs in human BE compared to normal squamous or EAC, and suggest that autophagy functions to improve cell survival after acid reflux injury. Autophagy may thus play a critical role in BE pathogenesis and progression. © 2015 Wiley Periodicals, Inc.

Ameliorative and antioxidant effects of myrtle berry seed (Myrtus communis) extract during reflux-induced esophagitis in rats

Context Myrtle, Myrtus communis L. (Myrtaceae), is a medicinal plant well known for its richness in phenolic compounds and its beneficial effects for the treatment of gastrointestinal disorders.Objective In the present work, the protective effect of the myrtle berry seed aqueous extract (MBSAE) against esophageal reflux (ER)-induced damage in esophagus mucosa as well as the mechanisms implicated was determined.Materials and methods In this respect, adult male Wistar rats were used and divided into seven groups: Control, ER, ER + various doses of MBSAE, ER + famotidine or ER + gallic acid. The ER was induced and animals were per orally (p.o.) treated with MBSAE or reference molecules during 6 h. The phytochemical screening was determined using colourimetric analysis.Results MBSAE is rich in total polyphenols and anthocyanins and exhibited an important in vitro antioxidant activity. In vivo, we firstly found that ER led to marked macroscopic and histopathological changes in esophagus. The results showed, also, that the ER was accompanied by a state of oxidative stress as assessed by an increase of lipid peroxidation, a decrease of the sulphhydryl groups and glutathione levels, as well as antioxidant enzyme activities depletion. MBSAE abrogated all morphological, histopathological and biochemical alterations. We showed also that ER increased esophageal calcium, hydrogen peroxide (H₂O₂) and free iron levels while MBSAE treatment protected against intracellular mediators deregulation.Conclusion Our data suggest that MBSAE exerted a potential protective effect against ER-induced damage in rat esophagus, at least in part, due to its antioxidant properties.

Barrett's esophagus and β-carotene therapy: symptomatic improvement in GERD and enhanced HSP70 expression in esophageal mucosa

INTRODUCTION

Epidemiological studies suggest a protective role for β-carotene with several malignancies. Esophageal adenocarcinoma frequently arises from Barrett's esophagus (BE). We postulated that β-carotene therapy maybe protective in BE.

MATERIALS AND METHOD

We conducted a prospective study in which 25 mg of β-carotene was administered daily for six-months to six patients. Each patient underwent upper endoscopy before and after therapy and multiple mucosal biopsies were obtained. Additionally, patients completed a gastroesophageal reflux disease (GERD) symptoms questionnaire before and after therapy and severity score was calculated. To study the effect of β-carotene at molecular level, tissue extracts of the esophageal mucosal biopsy were subjected to assessment of heat-shock protein 70 (HSP70).

RESULTS

A significant (p<0.05) reduction in mean GERD symptoms severity score from 7.0±2.4 to 2.7±1.7 following β-carotene therapy was noted. Measurement of Barrett's segment also revealed a significant reduction in mean length after therapy. In fact, two patients had complete disappearance of intestinal metaplasia. Furthermore, marked enhancement of HSP70 expression was demonstrated in biopsy specimens from Barrett's epithelium in four cases that were tested.

CONCLUSIONS

Long- term β-carotene therapy realizes amelioration of GERD symptoms along with restitution of the histological and molecular changes in esophageal mucosa of patients with BE, associated with concurrent increase in mucosal HSP70 expression.

Etiology and Prevention of Esophageal Cancer

BACKGROUND

Esophageal cancer (EC) occurs commonly, especially in Asia, and is the sixth leading cause of cancer deaths worldwide. Recently, great progress has been made in research on the etiology and prevention of EC.

SUMMARY

The major risk factors for esophageal squamous cell carcinoma (ESCC) are tobacco smoking and alcohol drinking, which act synergistically. Dietary parameters, including dietary carcinogens and insufficiency of micronutrients, could also be important risk factors in certain areas. A common etiological factor for both EC and some other cancers are low levels of intake of fruits and vegetables. With improvements in diet and drinking water in developing countries, the incidence of ESCC decreased. However, in economically well-developed countries, the incidence of esophageal adenocarcinoma (EAC) has markedly increased in the past 40 years. The major etiological factor for EAC is gastroesophageal reflux, which is also an etiological factor for gastric cardia adenocarcinoma (GCA). In certain areas of China, the occurrence of GCA is closely related to ESCC. Susceptibility genes for EC are starting to be discovered, and this may help to identify high-risk groups that have more need for preventive measures. Mitigation of the risk factors, early detection and treatment of precancerous lesions are effective approaches for prevention. Smoking cessation, avoidance of excessive alcohol, meat and caloric consumption, increasing physical activity and frequent consumption of vegetables and fruits are prudent lifestyle modifications for the prevention of EC as well as other diseases.

KEY MESSAGE

The etiology of EC includes tobacco smoking, alcohol drinking, low levels of intake of fruits and vegetables as well as gastroesophageal reflux and susceptibility genes.

PRACTICAL IMPLICATIONS

A healthy lifestyle including smoking cessation, increasing physical activity, consumption of vegetables as well as reduction of alcohol intake and caloric consumption are major approaches to the prevention of EC.

Animal Models of Barrett's Esophagus and Esophageal Adenocarcinoma-Past, Present, and Future

Esophageal adenocarcinoma is the fastest rising cancer in the United States. It develops from long-standing gastroesophageal reflux disease which affects >20% of the general population. It carries a very poor prognosis with 5-year survival <20%. The disease is known to sequentially progress from reflux esophagitis to a metaplastic precursor, Barrett's esophagus and then onto dysplasia and esophageal adenocarcinoma. However, only few patients with reflux develop Barrett's esophagus and only a minority of these turn malignant. The reason for this heterogeneity in clinical progression is unknown. To improve patient management, molecular changes which facilitate disease progression must be identified. Animal models can provide a comprehensive functional and anatomic platform for such a study. Rats and mice have been the most widely studied but disease homology with humans has been questioned. No animal model naturally simulates the inflammation to adenocarcinoma progression as in humans, with all models requiring surgical bypass or destruction of existing antireflux mechanisms. Valuable properties of individual models could be utilized to holistically evaluate disease progression. In this review paper, we critically examined the current animal models of Barrett's esophagus, their differences and homologies with human disease and how they have shaped our current understanding of Barrett's carcinogenesis.

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.

Strategies for the prevention of oesophageal adenocarcinoma

The incidence of oesophageal adenocarcinoma has increased by 500% over the past 30 years [1]. Improved understanding of the mechanisms of neoplastic progression provides an opportunity to reverse this trend. A thorough review of emerging strategies aiming to prevent the formation of oesophageal malignancy is presented. These include dietary modification, chemoprevention, early endoscopic identification and treatment of premalignant disease, and the potential for a non-endoscopic screening test. Oesophageal adenocarcinoma has become a major public health problem in the West and it is essential that clinicians are fully informed of risk reduction strategies so that they can be actively promoted in the community.

Nrf2 deficiency impairs the barrier function of mouse oesophageal epithelium

OBJECTIVE

As a major cellular defence mechanism, the Nrf2/Keap1 pathway regulates expression of genes involved in detoxification and stress response. Here we hypothesise that Nrf2 is involved in oesophageal barrier function and plays a protective role against gastro-oesophageal reflux disease (GERD).

DESIGN

Human oesophageal biopsy samples, mouse surgical models and Nrf2(-/-) mice were used to assess the role of the Nrf2/Keap1 pathway in oesophageal barrier function. Trans-epithelial electrical resistance (TEER) was measured with mini-Ussing chambers. HE staining and transmission electron microscopy were used to examine tissue morphology, while gene microarray, immunohistochemistry, western blotting and chromatin immunoprecipitation (ChIP) analysis were used to assess gene expression.

RESULTS

Nrf2 was expressed in normal oesophageal epithelium and activated in GERD of both humans and mice. Nrf2 deficiency and gastro-oesophageal reflux in mice, alone or in combination, reduced TEER and increased intercellular space in oesophageal epithelium. Nrf2 target genes and gene sets associated with oxidoreductase activity, mitochondrial biogenesis and energy production were downregulated in the oesophageal epithelium of Nrf2(-/-) mice. Consistent with the antioxidative function of Nrf2, a DNA oxidative damage marker (8OHdG) dramatically increased in oesophageal epithelial cells of Nrf2(-/-) mice compared with those of wild-type mice. Interestingly, ATP biogenesis, Cox IV (a mitochondrial protein) and Claudin 4 (Cldn4) expression were downregulated in the oesophageal epithelium of Nrf2(-/-) mice, suggesting that energy-dependent tight junction integrity was subject to Nrf2 regulation. ChIP analysis confirmed the binding of Nrf2 to Cldn4 promoter.

CONCLUSIONS

Nrf2 deficiency impairs oesophageal barrier function through disrupting energy-dependent tight junction.

Deferasirox (ICL670A) effectively inhibits oesophageal cancer growth in vitro and in vivo

BACKGROUND AND PURPOSE

Growing evidence implicates iron in the aetiology of gastrointestinal cancer. Furthermore, studies demonstrate that iron chelators possess potent anti-tumour activity, although whether iron chelators show activity against oesophageal cancer is not known.

EXPERIMENTAL APPROACH

The effect of the iron chelators, deferoxamine (DFO) and deferasirox, on cellular iron metabolism, viability and proliferation was assessed in two oesophageal adenocarcinoma cell lines, OE33 and OE19, and the squamous oesophageal cell line, OE21. A murine xenograft model was employed to assess the effect of deferasirox on oesophageal tumour burden. The ability of chelators to overcome chemoresistance and to enhance the efficacy of standard chemotherapeutic agents (cisplatin, fluorouracil and epirubicin) was also assessed.

KEY RESULTS

Deferasirox and DFO effectively inhibited cellular iron acquisition and promoted intracellular iron mobilization. The resulting reduction in cellular iron levels was reflected by increased transferrin receptor 1 expression and reduced cellular viability and proliferation. Treating oesophageal tumour cell lines with an iron chelator in addition to a standard chemotherapeutic agent resulted in a reduction in cellular viability and proliferation compared with the chemotherapeutic agent alone. Both DFO and deferasirox were able to overcome cisplatin resistance. Furthermore, in human xenograft models, deferasirox was able to significantly suppress tumour growth, which was associated with decreased tumour iron levels.

CONCLUSIONS AND IMPLICATIONS

The clinically established iron chelators, DFO and deferasirox, effectively deplete iron from oesophageal tumour cells, resulting in growth suppression. These data provide a platform for assessing the utility of these chelators in the treatment of oesophageal cancer patients.

The OGG1 Ser326Cys polymorphism and the risk of esophageal cancer: a meta-analysis

BACKGROUND

The oxoguanine DNA glycosylase (OGG1) Ser326Cys polymorphism has been implicated in susceptibility to esophageal cancer. Several studies investigated the association of this polymorphism with esophageal cancer in different populations. However, the results were contradictory. A meta-analysis was conducted to assess the association between the OGG1 Ser326Cys polymorphism and esophageal cancer susceptibility.

METHODS

Databases, including PubMed, EMBASE, China National Knowledge Infrastructure (CNKI), and Weipu Database were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of associations. A random-effects model was used.

RESULTS

Twelve studies involving 2363 cases and 3621 controls were included. Overall, a significant association between the OGG1 Ser326Cys polymorphism and esophageal cancer was observed for Cys/Cys versus Cys/Ser+Ser/Ser (OR=1.40; 95% CI 1.12-1.74; p=0.003; Pheterogeneity=0.18). In the subgroup analysis by ethnicity, a significant association was found among Asians (OR=1.51; 95% CI 1.15-1.96; p=0.002; Pheterogeneity=0.22), but not among Caucasians (OR=1.21; 95% CI 0.81-1.81; p=0.35; Pheterogeneity=0.21). In the subgroup analysis by pathologic type, we found that the Cys/Cys genotype was associated with increased esophageal squamous cell carcinoma risk (OR=1.86; 95% CI 1.36-2.53; p<0.0001; Pheterogeneity=0.73).

CONCLUSIONS

This meta-analysis suggested that the OGG1 Ser326Cys polymorphism was a risk factor of esophageal cancer.

Poultry and fish intake and risk of esophageal cancer: A meta-analysis of observational studies

AIM

Mixed results regarding the association between white meat (including poultry and fish) intake and the risk of esophageal cancer (EC) have been reported. We performed a meta-analysis to provide a quantitative assessment of this association.

METHOD(S)

Relevant studies were identified in MEDLINE until December 31, 2012. Summary relative risks (SRRs) with 95% confidence intervals (CIs) were pooled with a random-effects model.

RESULTS

A total of 20 articles, including 3990 cases with EC, were included in this meta-analysis. Compared to individuals with the lowest level of fish intake, individuals with the highest fish intake were found to have reduced risk of EC (SRRs = 0.69; 95% CIs: 0.57-0.85), while poultry intake was not associated with EC (SRRs = 0.83; 95% CIs: 0.62-1.12). Total fish consumption is associated with reduced esophageal squamous cell carcinoma (ESCC) risk, while poultry consumption was not associated with ESCC risk. Additionally, neither poultry nor fish consumption was associated with esophageal adenocarcinoma risk.

CONCLUSION(S)

Our results suggest that fish consumption may have a potential role in EC prevention, while poultry intake has no effect. However, because the majority of data was from case-control studies, further well-designed prospective studies are warranted.

Defective antioxidant systems in cervical cancer

Cervical cancer remains a great problem for woman health, as it is the second deadly cancer of females worldwide. The infection of human papilloma virus (HPV) is the major risk factor for this cancer, although several other factors are also associated. Oxidative stress or antioxidant deficiency has been frequently identified to be associated with cervical cancer. Defects in the antioxidant enzyme systems are reported to play important role behind this antioxidant deficiency, which is responsible for the production of reactive oxygen species and ultimately, DNA damage in cervical cells. In response, cells become more vulnerable to HPV infection for cervical cancer development. Recently, antioxidant therapies or dietary supplementation of antioxidants have gained considerable interests in the cervical cancer treatment. In this study, we have reviewed the association of defective antioxidant systems and cervical cancer development. The recent advances in both of the basic and clinical research focusing on possible antioxidant therapy have also been discussed.

Cigarette smoke induces nuclear translocation of heme oxygenase 1 (HO-1) in prostate cancer cells: nuclear HO-1 promotes vascular endothelial growth factor secretion

Prostate cancer is the second leading cause of male-cancer related death in the United States. Despite a number of evidence-based studies which strongly suggest an association between cigarette smoking and prostate cancer, the underlying biological mechanism is largely unknown. Heme oxygenase 1 (HO-1) has been implicated in maintaining cellular homeostasis, but also in tumor angiogenesis. Nuclear HO-1 protein expression has been observed in various types of tumors including prostate cancer. These studies, however, were reported as clinical and pathological observations, and failed to investigate nuclear HO-1 at the molecular level in cancer. The present study explores the relationship between cigarette smoke and nuclear HO-1-modulated promotion of vascular endothelial growth factor (VEGF) secretion. We have demonstrated that cigarette smoke medium (SM)-induced HO-1 mRNA expression and upregulated HO-1 protein levels in the prostate cancer cell lines DU145 and PC3. We also observed that SM significantly induced nuclear expression of HO-1, and enhanced secretion of VEGF in cells. Nuclear-directed expression of HO-1 activated the transcriptional activity of VEGF and promoted VEGF secretion in prostate cancer cells. This study provides new insights into the molecular mechanism by which cigarette smoke-induced nuclear translocation of HO-1 promotes VEGF secretion in prostate cancer cells. Nuclear HO-1 may, therefore, constitute an attractive therapeutic target to inhibit angiogenesis and the progression of prostate cancer.

Radical decisions in cancer: redox control of cell growth and death

Free radicals play a key role in many physiological decisions in cells. Since free radicals are toxic to cellular components, it is known that they cause DNA damage, contribute to DNA instability and mutation and thus favor carcinogenesis. However, nowadays it is assumed that free radicals play a further complex role in cancer. Low levels of free radicals and steady state levels of antioxidant enzymes are responsible for the fine tuning of redox status inside cells. A change in redox state is a way to modify the physiological status of the cell, in fact, a more reduced status is found in resting cells while a more oxidative status is associated with proliferative cells. The mechanisms by which redox status can change the proliferative activity of cancer cells are related to transcriptional and posttranscriptional modifications of proteins that play a critical role in cell cycle control. Since cancer cells show higher levels of free radicals compared with their normal counterparts, it is believed that the anti-oxidative stress mechanism is also increased in cancer cells. In fact, the levels of some of the most important antioxidant enzymes are elevated in advanced status of some types of tumors. Anti-cancer treatment is compromised by survival mechanisms in cancer cells and collateral damage in normal non-pathological tissues. Though some resistance mechanisms have been described, they do not yet explain why treatment of cancer fails in several tumors. Given that some antitumoral treatments are based on the generation of free radicals, we will discuss in this review the possible role of antioxidant enzymes in the survival mechanism in cancer cells and then, its participation in the failure of cancer treatments.

NRF2 mutation confers malignant potential and resistance to chemoradiation therapy in advanced esophageal squamous cancer

Esophageal squamous cancer (ESC) is one of the most aggressive tumors of the gastrointestinal tract. A combination of chemotherapy and radiation therapy (CRT) has improved the clinical outcome, but the molecular background determining the effectiveness of therapy remains unknown. NRF2 is a master transcriptional regulator of stress adaptation, and gain of-function mutation of NRF2 in cancer confers resistance to stressors including anticancer therapy. Direct resequencing analysis revealed that Nrf2 gain-of-function mutation occurred recurrently (18/82, 22%) in advanced ESC tumors and ESC cell lines (3/10). The presence of Nrf2 mutation was associated with tumor recurrence and poor prognosis. Short hairpin RNA-mediated down-regulation of NRF2 in ESC cells that harbor only mutated Nrf2 allele revealed that themutant NRF2 conferred increased cell proliferation, attachment-independent survival, and resistance to 5-fluorouracil and γ-irradiation. Based on the Nrf2 mutation status, gene expression signatures associated with NRF2 mutation were extracted from ESC cell lines, and their potential utility for monitoring and prognosis was examined in a cohort of 33 pre-CRT cases of ESC. The molecular signatures of NRF2 mutation were significantly predictive and prognostic for CRT response. In conclusion, recurrent NRF2 mutation confers malignant potential and resistance to therapy in advanced ESC, resulting in a poorer outcome. Molecular signatures of NRF2 mutation can be applied as predictive markers of response to CRT, and efficient inhibition of aberrant NRF2 activation could be a promising approach in combination with CRT.

The association of manganese superoxide dismutase expression in Barrett's esophageal progression with MnTBAP and curcumin oil therapy

BACKGROUND

The aim of this study was to investigate the relationship between reflux induced bile insult and MnSOD expression, as well as to examine therapies to preserve MnSOD expression. Additionally, we sought to examine the relationship between MnSOD protein expression and MnSOD enzymatic activity.

METHODS

MnSOD protein expression was determined by Western blot assay and enzymatic activity was determined by SOD assay. The enzymatic activity of the Het-1A and Bar-T cells were compared both before and after treatments.

RESULTS

MnSOD expression in Het-1A cells was decreased after bile salt exposure. The cells that received MnTBAP or curcumin oil pretreatment showed increased MnSOD expression compared with control untreated cells. The Bar-T cells showed an increase in MnSOD expression after treatment with bile salts. The cells that were pretreated with MnTBAP displayed a larger increase in MnSOD expression compared with the cells that were not pretreated prior to bile salt exposure. The MnSOD activity was significantly different between the untreated cell lines (P = 0.01) and after treatment with bile salt (P = 0.03). Additionally, Bar-T cells had significantly less MnSOD activity than Het-1A cells after each of the pretreatments.

CONCLUSIONS

We demonstrated preservation of MnSOD expression in Het-1A cells that were pretreated with antioxidants including MnTBAP, curcumin oil, and certain berry extracts. Additionally, we demonstrated that Bar-T cells have significantly less MnSOD activity than Het-1A cells. These finding have important implications for future studies regarding chemoprevention and the treatment of esophageal cancer.

Dietary fat and meat intakes and risk of reflux esophagitis, Barrett's esophagus and esophageal adenocarcinoma

The aim of our study was to investigate whether dietary fat and meat intakes are associated with reflux esophagitis (RE), Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC). In this all-Ireland case-control study, dietary intake data were collected using a food frequency questionnaire in 219 RE patients, 220 BE patients, 224 EAC patients and 256 frequency-matched controls between 2002 and 2005. Unconditional multiple logistic regression analysis was used to examine the association between dietary variables and disease risk using quartiles of intake, to attain odds ratios (ORs) and 95% confidence intervals (95% CIs), while adjusting for potential confounders. Patients in the highest quartile of total fat intake had a higher risk of RE (OR = 3.54; 95% CI = 1.32-9.46) and EAC (OR = 5.44; 95% CI = 2.08-14.27). A higher risk of RE and EAC was also reported for patients in the highest quartile of saturated fat intake (OR = 2.79; 95% CI = 1.11-7.04; OR = 2.41; 95% CI = 1.14-5.08, respectively) and monounsaturated fat intake (OR = 2.63; 95% CI = 1.01-6.86; OR = 5.35; 95% CI = 2.14-13.34, respectively). Patients in the highest quartile of fresh red meat intake had a higher risk of EAC (OR = 3.15; 95% CI = 1.38-7.20). Patients in the highest category of processed meat intake had a higher risk of RE (OR = 4.67; 95% CI = 1.71-12.74). No consistent associations were seen for BE with either fat or meat intakes. Further studies investigating the association between dietary fat and food sources of fat are needed to confirm these results.

p73 protein regulates DNA damage repair

Although the p53 tumor suppressor is relatively well characterized, much less is known about the functions of other members of the p53 family, p73 and p63. Here, we present evidence that in specific pathological conditions caused by exposure of normal cells to bile acids in acidic conditions, p73 protein plays the predominant role in the DNA damage response. These pathological conditions frequently occur during gastric reflux in the human esophagus and are associated with progression to esophageal adenocarcinoma. We found that despite strong DNA damage induced by bile acid exposure, only p73 (but not p53 and p63) is selectively activated in a c-Abl kinase-dependent manner. The activated p73 protein induces DNA damage repair. Using a human DNA repair PCR array, we identified multiple DNA repair genes affected by p73. Two glycosylases involved in base excision repair, SMUG1 and MUTYH, were characterized and found to be transcriptionally regulated by p73 in DNA damage conditions. Using a surgical procedure in mice, which recapitulates bile acid exposure, we found that p73 deficiency is associated with increased DNA damage. These findings were further investigated with organotypic and traditional cell cultures. Collectively our studies demonstrate that p73 plays an important role in the regulation of DNA damage repair.

Inflammation and oxidative stress in gastroesophageal reflux disease

The etiology of esophageal mucosal injury is complex, since it may involve the reflux of gastric acid, bile acid, and pancreatic juice, external factors such as drugs and alcohol, or functional factors such as esophagogastric motility. The mechanism of esophageal mucosal injury has gradually been understood at the molecular biological level. It is particularly important that pro-inflammatory factors, such as inflammatory cytokines (interleukin-6 and -8), leukocytes and oxidative stress, have been demonstrated to be involved in the development of gastroesophageal reflux disease (GERD) including nonerosive reflux disease (NERD). In addition, nociceptors such as acid-sensitive vanilloid receptors, protease-activated receptors and substance P have also been implicated in the pathogenesis of neurogenic inflammation in NERD patients with esophageal hypersensitivity. The development of new therapy with anti-inflammatory and anti-oxidant effects is expected to assist in the treatment of intractable NERD/GERD and the prevention of carcinogenesis.

Iron intake and markers of iron status and risk of Barrett's esophagus and esophageal adenocarcinoma

OBJECTIVE

To investigate the association between iron intake and iron status with Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC).

METHODS

A total of 220 BE patients, 224 EAC patients, and 256 frequency-matched controls completed a lifestyle and food frequency questionnaire and provided serum and toenail samples between 2002 and 2005. Using multiple logistic regression, odds ratios (OR) and 95% confidence intervals (95% CI) were calculated within quartiles of intake/status.

RESULTS

Comparing the fourth to the first quartile, ferritin (OR 0.47; 95% CI: 0.23, 0.97) and transferrin saturation (OR 0.41; 95% CI: 0.20, 0.82) were negatively associated with BE; while total iron binding capacity was positively associated per 50 μg/dl increment (OR 1.47; 95% CI: 1.12, 1.92). Comparing the fourth to the first quartile, iron intake (OR 0.50; 95% CI: 0.25, 0.98), non-heme iron intake per 10 mg/day increment (OR 0.29; 95% CI: 0.08, 0.99), and toenail iron (OR 0.40; 95% CI: 0.17, 0.93) were negatively associated with EAC; while heme iron intake was positively associated (OR 3.11 95% CI: 1.46, 6.61).

PRINCIPAL CONCLUSION

In contrast to the hypothesis that increased iron intakes and higher iron stores are a risk factor for BE and EAC, this study suggests that higher iron intakes and stores may have a protective association with BE and EAC, with the exception of what was found for heme iron intake.

Dietary factors and the risks of oesophageal adenocarcinoma and Barrett's oesophagus

Incidence rates for oesophageal adenocarcinoma have increased by over 500% during the past few decades without clear reasons. Gastro-oesophageal reflux disease, obesity and smoking have been identified as risk factors, although the demographic distribution of these risk factors is not consistent with the demographic distribution of oesophageal adenocarcinoma, which is substantially more common among whites and males than any other demographic groups. Numerous epidemiological studies have suggested associations between dietary factors and the risks of oesophageal adenocarcinoma and its precursor, Barrett's oesophagus, though a comprehensive review is lacking. The main aim of the present review is to consider the evidence linking dietary factors with the risks of oesophageal adenocarcinoma, Barrett's oesophagus, and the progression from Barrett's oesophagus to oesophageal adenocarcinoma. The existing epidemiological evidence is strongest for an inverse relationship between intake of vitamin C, β-carotene, fruits and vegetables, particularly raw fruits and vegetables and dark green, leafy and cruciferous vegetables, carbohydrates, fibre and Fe and the risk of oesophageal adenocarcinoma and Barrett's oesophagus. Patients at higher risk for Barrett's oesophagus and oesophageal adenocarcinoma may benefit from increasing their consumption of fruits and vegetables and reducing their intake of red meat and other processed food items. Further research is needed to evaluate the relationship between diet and the progression of Barrett's oesophagus to oesophageal adenocarcinoma. Evidence from cohort studies will help determine whether randomised chemoprevention trials are warranted for the primary prevention of Barrett's oesophagus or its progression to cancer.

Evaluation of the heme oxygenase-1 expression in esophagitis and esophageal cancer induced by different reflux experimental models and diethylnitrosamine

PURPOSE: To study the expression of heme-oxygenase-1 (HO-1), an enzyme induced by oxidative stress, in specimens obtained from an experimental model in rats that evaluated the role of gastric and duodenal reflux in esophageal carcinogenesis. METHODS: Esophageal specimens embedded in paraffin obtained from different experimental groups of rats were used for immunohistochemistry analysis of HO-1 expression. The rats had been divided into the following groups and were killed after 22 weeks: (1) cardioplasty to induce acid reflux; (2) esophagoduodenal anastomosis to induce duodenal reflux; (3) no treatment; (4) cardioplasty + diethylnitrosamine (DEN); (5) esophagoduodenal anastomosis + DEN; and (6) DEN. The study sample comprised 3 specimens from each group with the most severe histopathological lesions found on each study branch. RESULTS: The expression of HO-1 was seen only in rat specimens submitted to esophagoduodenal anastomosis (Groups 2 and 5), and the analysis of mean fluorescence intensity revealed a significant increase of HO-1 expression (4.8 and 4.6 fold, respectively) when compared with the control group (Group 3) (p<0.05). The main target for HO-1 induction was the inflammatory cells inside the tumor or in subepithelial areas. Rats exposed to gastric reflux had no HO-1 expression. CONCLUSION: Reflux esophagitis induced by reflux of duodenal contents, which provoked considerable oxidative stress, may play an important role in esophageal carcinogenesis. Acid reflux did not induce oxidative stress in this experimental model.

Urinary 8-OHdG: A marker of oxidative stress to DNA and total antioxidant status in essential hypertension with South Indian population

Establishment of non-invasive urinary biomarker for the early prediction of essential hypertension (EH) is important. We evaluated whether estimation of urinary DNA, serves as a marker to predict the extent of cellular oxidative stress in essential hypertension. A total of 180 South Indian subjects aged 30-65 were recruited for the study. Of these hypertensive subjects investigated, 30 were newly diagnosed and were not on any antihypertensive drugs, but had systolic blood pressure 140-160 mmHg and diastolic blood pressure 95-100 mmHg and 75 hypertensive patients who already on drug therapy for one year and 75 were South Indian normotensive healthy controls with blood pressure ≤ 120/80 mmHg. The 8-OHdG level in urine was significantly increased in hypertensive patients (both newly diagnosed and who already on drug therapy) compared with control group. The significant increase in 8-OHdG was observed in newly diagnosed hypertensive patients compared with hypertensive patients who already on drug therapy. There was a significant decrease in serum TAS value in essential hypertensive group when compared to control group. The urinary 8-OHdG was independently correlated with serum TAS. Decreased TAS levels, which reflect to increased oxidative stress, may be the reason of increased urinary 8-OHdG in South Indian hypertensive patients. Our preliminary data suggest that the competitive ELISA for 8-OHdG appears to be a simple method for quantifying the extent of oxidative stress.

Positive correlation of image analysis by mini-endoscopy with micro-PET scan and histology in rats after esophagoduodenal anastomosis

BACKGROUND

Visual inspection of induced carcinogenic transformation is of crucial interest when evaluating growth patterns and therapeutic effects. In previous studies we have used micro-PET scan to analyze the esophageal adenocarcinoma (EAC) transformation in an intact rat model of esophagoduodenal anastomosis (EDA), in which intestinal metaplasia and EAC were reproduced successfully. Our current study aimed to test the feasibility of evaluating the outcomes of our EDA model with a recently developed mini-endoscope.

METHODS

EDA was performed as described previously. Postoperative rats underwent evaluation with upper endoscopy with the mini-endoscope (±endoscopic biopsy) and a micro-PET scan with (18)F-FDG 3 months after the EDA procedure. Rats were euthanized and the esophagi were collected for histological observation, immunohistochemical staining, and TdT labeling assay. We compared the endoscopic images with the radiographic images of (18)F-FDG uptake by micro-PET scan and correlated the endoscopic images with the histological changes in the EDA rats.

RESULTS

The endoscope provided visualization of the entire esophageal tract and upper stomach, with the smallest detectable lesion being 0.5 mm in diameter. Mini-endoscopy was performed regularly and was tolerated without any significant procedure-related alterations in the esophageal tract. The visualized esophageal lesion correlated well with the micro-PET image and the histological changes in the EDA rats.

CONCLUSIONS

The new mini-endoscope constitutes a practical and reliable tool for diagnosis and regular follow-up of the esophagus in rats. Lesions identified by endoscopic observation were consistent with the changes found in the micro-PET scan, histopathology, and alteration of cellular and molecular events in esophageal mucosa. This instrument will allow for serial endoscopic evaluations, similar to endoscopic screening in humans, which will significantly enhance the preclinical development and evaluation of experimental intravesical antitumor therapies.

Successful evaluation of a new animal model using mice for esophageal adenocarcinoma

INTRODUCTION

For the better understanding of the pathophysiological events occurring in the sequence inflammation-metaplasia-carcinoma in esophageal adenocarcinoma, an animal model would be desirable. In the past, several rat models have been used yielding conflicting results. Some demonstrated a sequence similar to the human situation whereas others failed to initiate true esophageal adenocarcinoma or even Barrett's metaplasia. For the study of the molecular events involved in the carcinogenesis of Barrett's carcinoma, a mouse model would be much more promising since most of the genetically altered animals are mice. However, as of now no such model exists, in the past predominately due to the high mortality involved with the surgical procedure to create a mixed duodenogastric reflux.

METHODS

Forty BALB-C mice weighing between 22 and 25 g underwent an esophagojejunostomy. The animals were sacrificed at 3, 4, and 5 months. Pathological evaluation was performed with HE staining.

RESULTS

Overall mortality was 17%. However, mortality within the first ten animals was 30%. Reasons were technical problems with the anastomosis, opening of the pleural cavity, or bleeding events. All animals had a severe esophagitis regardless of the time. Intestinal metaplasia could be found in 60% of the animals after 4 months and esophageal adenocarcinoma in 55% after 5 months. One animal showed multiple lung metastases.

CONCLUSION

After a certain learning curve esophagojejunostomy is feasible in mice with an acceptable mortality rate and leads to esophageal adenocarcinoma.

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.

Diet composition affects surgery-associated weight loss in rats with a compromised alimentary tract

BACKGROUND

Esophageal adenocarcinoma (EAC) is the fastest growing cancer in terms of incidence and has a high mortality rate. The animal model to study EAC uses esophagoduodenal anastomosis (EDA) to induce mixed-reflux (bile/acid) causing esophagitis, Barrett's esophagus, and EAC sequence within 6 mo. However, the lack of fully functional stomach in these rats leads to the development of malnutrition.

METHODS

We have assessed the ability of a chemically pure, purified ingredient diet (AIN-93M) to reduce surgery-associated malnutrition in rats that have undergone the EDA-surgery. Animals were either sham- (SH) or EDA-operated and fed either a grain-based rodent diet (RD) (SH-RD, n=3; EDA-RD, n=10) or a purified diet (PD) (SH-PD, n=4; EDA-PD, n=11). The animals were weighed periodically for assessment of weight gain and euthanized at the end of 24 wk to measure esophageal tumor incidence.

RESULTS

Animals that underwent sham surgery continued to gain weight throughout the study period and no tumors were detected. The EDA-operated animals had significantly lower weight gain compared with sham animals. There was no significant difference in weight gain among EDA animals fed two different types of diets until 9 wk after the surgery. After 9 wk, EDA-RD continued to lose weight significantly, whereas the weight loss leveled in EDA-PD (P<0.001). At termination, neither tissue histopathology nor tumor incidence was significantly different between the groups.

CONCLUSION

These results show that compared with a natural ingredient diet, a purified ingredient diet can reduce surgery-associated weight loss in rats with a compromised alimentary tract. This reduction in malnutrition has the potential to reduce the confounding effects of weight loss on future animal studies reported.

CDX2 hox gene product in a rat model of esophageal cancer

Background

Barrett's mucosa is the precursor of esophageal adenocarcinoma. The molecular mechanisms behind Barrett's carcinogenesis are largely unknown. Experimental models of longstanding esophageal reflux of duodenal-gastric contents may provide important information on the biological sequence of the Barrett's oncogenesis.

Methods

The expression of CDX2 hox-gene product was assessed in a rat model of Barrett's carcinogenesis. Seventy-four rats underwent esophago-jejunostomy with gastric preservation. Excluding perisurgical deaths, the animals were sacrificed at various times after the surgical treatment (Group A: <10 weeks; Group B: 10–30 weeks; Group C: >30 weeks).

Results

No Cdx2 expression was detected in either squamous epithelia of the proximal esophagus or squamous cell carcinomas. De novo Cdx2 expression was consistently documented in the proliferative zone of the squamous epithelium close to reflux ulcers (Group A: 68%; Group B: 64%; Group C: 80%), multilayered epithelium and intestinal metaplasia (Group A: 9%; Group B: 41%; Group C: 60%), and esophageal adenocarcinomas (Group B: 36%; Group C: 35%). A trend for increasing overall Cdx2 expression was documented during the course of the experiment (p = 0.001).

Conclusion

De novo expression of Cdx2 is an early event in the spectrum of the lesions induced by experimental gastro-esophageal reflux and should be considered as a key step in the morphogenesis of esophageal adenocarcinoma.

Inflammation and esophageal carcinogenesis

The incidence of esophageal adenocarcinoma is increasing largely in Western populations, and patients diagnosed with this cancer continue to have a poor prognosis. The major risk factors are gastroesophageal reflux disease and Barrett's esophagus, both of which are associated with inflammation of the esophageal squamous epithelium, a condition called reflux esophagitis. The cellular mechanisms contributing to cancer development in the esophagus are poorly understood. The chronic inflammation that is present in Barrett's esophagus creates an environment suitable for DNA damage and altered expression of genes involved in cellular proliferation and inhibition of apoptosis. Key players in the inflammatory cascade include generation of free radicals, activation of kinases pathways and transcription factors, and production of cytokines and inflammatory enzymes. The current review highlights the link between reflux-induced inflammation and esophageal carcinogenesis. Understanding the molecular pathways involved in inflammation-associated esophageal tumorigenesis could enable the development of targeted therapies and offer a better therapeutic treatment in esophageal cancer.

Hemochromatosis gene status as a risk factor for Barrett's esophagus

Conditions causing high iron levels, such as hemochromatosis, are proposed risk factors for esophageal adenocarcinoma. Although this hypothesis is supported by animal models, no human data currently exist. We conducted a case-control study of persons with a new Barrett's esophagus diagnosis (cases), persons with gastroesophageal reflux disease (GERD) (without Barrett's esophagus), and population controls. Subjects completed detailed examinations and assays for hemochromatosis mutations and serum iron stores. We evaluated 317 cases, 306 GERD patients, and 308 population controls. There was no significant association between Barrett's esophagus and any hemochromatosis gene defect (odds ratio [OR] = 1.32, 95% confidence interval [CI]: 0.95-1.84), a moderate or severe mutation (OR = 1.54, 95% CI: 0.94-2.52), or a severe mutation (C282Y homozygote or C282Y/H63D heterozygote; OR = 0.77, 95% CI: 0.24-2.48) compared with the population controls. As expected, gene defects were associated with increased iron stores. We can conclude from our findings that Barrett's esophagus was not associated with hemochromatosis gene defects, although we cannot exclude small effects.

Iron intake and body iron stores as risk factors for Barrett's esophagus: a community-based study

OBJECTIVE

High iron stores are a proposed modifiable risk factor for esophageal adenocarcinoma, but minimal human data exist. We evaluated whether iron intake and iron stores were associated with Barrett's esophagus, a metaplastic change that is a strong risk factor for esophageal adenocarcinoma.

METHODS

We conducted a case-control study within the Kaiser Permanente Northern California population. We identified all persons with a new diagnosis of Barrett's esophagus (cases); they were matched to persons with GERD (without Barrett's esophagus) and to population controls. Subjects completed examinations, dietary questionnaires, and testing for serum iron stores (ferritin and transferrin saturation). Analyses used unconditional logistic regression.

RESULTS

We evaluated 319 cases, 312 GERD patients, and 313 population controls. Compared with population controls, Barrett's esophagus patients had lower dietary iron intakes (4th vs 1st quartiles, odds ratio [OR]= 0.37, 95% confidence interval [CI] 0.17-0.80), similar total iron intakes (including supplement use), and lower iron stores (4th vs 1st quartiles, ferritin OR = 0.24, 95% CI 0.14-0.40;% transferrin saturation OR = 0.66, 95% CI 0.41-1.04; P value trend <0.01 and 0.03, respectively). Similar associations were observed in comparisons with GERD controls and among subjects without clear sources of blood loss on endoscopy.

CONCLUSIONS

Patients with Barrett's esophagus had lower dietary iron intakes and lower serum iron stores than controls in our population. These findings do not provide support for the current hypothesis that high iron stores or a high iron intake are risk factors for Barrett's esophagus, a potential early event in the carcinogenic sequence for esophageal adenocarcinoma.

8-Hydroxy-2'-deoxy-guanosine is a risk factor for development of hepatocellular carcinoma in patients with chronic hepatitis C virus infection

BACKGROUND AND AIM

Increased production of reactive oxygen species, which cause oxidative DNA damage, is considered to be related to hepatocarcinogenesis. 8-Hydroxy-2'-deoxy-guanosine (8-OHdG) is a useful marker of DNA damage induced by oxidative stress. The aim of this study was to determine whether expression of 8-OHdG is a risk factor for the development of hepatocellular carcinoma (HCC) in patients with hepatitis C virus (HCV) infection.

METHODS

The expression of 8-OHdG in liver biopsy specimens was assessed immunohistochemically. In total, 104 patients with chronic HCV infection who were diagnosed on liver biopsy between January 1987 and December 2002 were studied retrospectively. Univariate and multivariate analyses using age, gender, habitual drinking, tobacco exposure, diabetes mellitus, serum alanine aminotransferase level, HCV genotype, hepatic fibrosis, inflammation, steatosis, and 8-OHdG expression in liver biopsy specimens were conducted to identify factors related to the development of HCC.

RESULTS

On multivariate analysis, 8-OHdG and fibrosis were independent and significant risk factors for HCC development (relative risk, 2.48; P = 0.023; relative risk, 5.35; P = 0.001, respectively). Furthermore, the cumulative incidence rate of HCC in 39 patients with high 8-OHdG expression levels was significantly greater than that in 65 patients with low 8-OHdG expression levels (P = 0.043). In addition, liver 8-OHdG expression was correlated with hepatic inflammation.

CONCLUSIONS

8-OHdG is a risk factor for the development of HCC in patients with chronic HCV infection. Patients with chronic HCV who express 8-OHdG should be monitored carefully for the development of HCC.