Goblet Cell Ratio in Combination with Differentiation and Stem Cell Markers in Barrett Esophagus Allow Distinction of Patients with and without Esophageal Adenocarcinoma

Signaling Pathways in the Pathogenesis of Barrett's Esophagus and Esophageal Adenocarcinoma

Barrett's esophagus (BE) is a premalignant lesion that can develop into esophageal adenocarcinoma (EAC). The development of Barrett's esophagus is caused by biliary reflux, which causes extensive mutagenesis in the stem cells of the epithelium in the distal esophagus and gastro-esophageal junction. Other possible cellular origins of BE include the stem cells of the mucosal esophageal glands and their ducts, the stem cells of the stomach, residual embryonic cells and circulating bone marrow stem cells. The classical concept of healing a caustic lesion has been replaced by the concept of a cytokine storm, which forms an inflammatory microenvironment eliciting a phenotypic shift toward intestinal metaplasia of the distal esophagus. This review describes the roles of the NOTCH, hedgehog, NF-κB and IL6/STAT3 molecular pathways in the pathogenesis of BE and EAC.

Telomere shortening accelerates tumor initiation in the L2-IL1B mouse model of Barrett esophagus and emerges as a possible biomarker

Barrett’s esophagus (BE) is a precursor of the esophageal adenocarcinoma (EAC). BE- development and its progression to cancer is associated with gastroesophageal reflux disease. However, there is currently no molecular risk prediction model that accurately identifies patients at high risk for EAC. Here, we investigated the impact of shortened telomeres in a mouse model for Barrett esophagus (L2-IL1B). The L2-IL1B mouse model is characterized by IL-1β-mediated inflammation, which leads to a Barrett-like metaplasia in the transition zone between the squamous forestomach and glandular cardia/stomach. Telomere shortening was achieved by mTERC knockout. In the second generation (G2) of mTERC knockout L2-IL1B.mTERC^−/− G2 mice exhibited telomere dysfunction with significantly shorter telomeres as measured by qFISH compared to L2-IL1B mice, correlating with stronger DNA damage in the form of phosphorylation of H2AX (γH2AX). Macroscopically, tumor area along the squamocolumnar junction (SCJ) was increased in L2-IL1B.mTERC^−/− G2 mice, along with increased histopathological dysplasia. In vitro studies indicated increased organoid formation capacity in BE tissue from L2-IL1B.mTERC^−/− G2 mice. In addition, pilot studies of human BE-, dysplasia- and EAC tissue samples confirmed that BE epithelial cells with or without dysplasia (LGD) had shorter telomeres compared to gastric cardia tissue. Of note, differentiated goblet cells retained longer telomeres than columnar lined BE epithelium. In conclusion, our studies suggest that shortened telomeres are functionally important for tumor development in a mouse model of BE and are associated with proliferating columnar epithelium in human BE. We propose that shortened telomeres should be evaluated further as a possible biomarker of cancer risk in BE patients.

Barrett's esophagus: The pathomorphological and molecular genetic keystones of neoplastic progression

Barrett's esophagus is a widespread chronically progressing disease of heterogeneous nature. A life threatening complication of this condition is neoplastic transformation, which is often overlooked due to lack of standardized approaches in diagnosis, preventative measures and treatment. In this essay, we aim to stratify existing data to show specific associations between neoplastic transformation and the underlying processes which predate cancerous transition. We discuss pathomorphological, genetic, epigenetic, molecular and immunohistochemical methods related to neoplasia detection on the basis of Barrett's esophagus. Our review sheds light on pathways of such neoplastic progression in the distal esophagus, providing valuable insight into progression assessment, preventative targets and treatment modalities. Our results suggest that molecular, genetic and epigenetic alterations in the esophagus arise earlier than cancerous transformation, meaning the discussed targets can help form preventative strategies in at-risk patient groups.

High-Fructose Diet Alters Intestinal Microbial Profile and Correlates with Early Tumorigenesis in a Mouse Model of Barrett’s Esophagus

Esophageal adenocarcinoma (EAC) is mostly prevalent in industrialized countries and has been associated with obesity, commonly linked with a diet rich in fat and refined sugars containing high fructose concentrations. In meta-organisms, dietary components are digested and metabolized by the host and its gut microbiota. Fructose has been shown to induce proliferation and cell growth in pancreas and colon cancer cell lines and also alter the gut microbiota. In a previous study with the L2-IL-1B mouse model, we showed that a high-fat diet (HFD) accelerated EAC progression from its precursor lesion Barrett’s esophagus (BE) through changes in the gut microbiota. Aiming to investigate whether a high-fructose diet (HFrD) also alters the gut microbiota and favors EAC carcinogenesis, we assessed the effects of HFrD on the phenotype and intestinal microbial communities of L2-IL1B mice. Results showed a moderate acceleration in histologic disease progression, a mild effect on the systemic inflammatory response, metabolic changes in the host, and a shift in the composition, metabolism, and functionality of intestinal microbial communities. We conclude that HFrD alters the overall balance of the gut microbiota and induces an acceleration in EAC progression in a less pronounced manner than HFD.

Randomized Controlled Trial of the Gastrin/CCK2 Receptor Antagonist Netazepide in Patients with Barrett's Esophagus

Hypergastrinemia has been associated with high-grade dysplasia and adenocarcinoma in patients with Barrett's esophagus, and experimental studies suggest proinflammatory and proneoplastic effects of gastrin on Barrett's esophagus. This is of potential concern, as patients with Barrett's esophagus are treated with medications that suppress gastric acid production, resulting in increased physiologic levels of gastrin. We aimed to determine whether treatment with the novel gastrin/CCK₂ receptor antagonist netazepide reduces expression of markers associated with inflammation and neoplasia in Barrett's esophagus. This was a randomized, double-blind, placebo-controlled trial of netazepide in patients with Barrett's esophagus without dysplasia. Subjects were treated for 12 weeks, with endoscopic assessment at baseline and at end of treatment. The primary outcome was within-individual change in cellular proliferation as assessed by Ki67. Secondary analyses included changes in gene expression, assessed by RNA-sequencing, and safety and tolerability. A total of 20 subjects completed the study and were included in the analyses. There was no difference between arms in mean change in cellular proliferation (netazepide: +35.6 Ki67+ cells/mm², SD 620.7; placebo: +307.8 Ki67+ cells/mm², SD 640.3; P = 0.35). Netazepide treatment resulted in increased expression of genes related to gastric phenotype (TFF2, MUC5B) and certain cancer-associated markers (REG3A, PAX9, MUC1), and decreased expression of intestinal markers MUC2, FABP1, FABP2, and CDX1 No serious adverse events related to study drug occurred. The gastrin/CCK₂ receptor antagonist netazepide did not reduce cellular proliferation in patients with nondysplastic Barrett's esophagus. Further research should focus on the biological effects of gastrin in Barrett's esophagus.Prevention Relevance: Treatment of patients with Barrett's esophagus with a gastrin/CCK₂ receptor antagonist did not have obvious chemopreventive effects.

Alteration of protein expression and spliceosome pathway activity during Barrett's carcinogenesis

BACKGROUND

Barrett's esophagus (BE) is a known precursor lesion and the strongest risk factor for esophageal adenocarcinoma (EAC), a common and lethal type of cancer. Prediction of risk, the basis for efficient intervention, is commonly solely based on histologic examination. This approach is challenged by problems such as inter-observer variability in the face of the high heterogeneity of dysplastic tissue. Molecular markers might offer an additional way to understand the carcinogenesis and improve the diagnosis-and eventually treatment. In this study, we probed significant proteomic changes during dysplastic progression from BE into EAC.

METHODS

During endoscopic mucosa resection, epithelial and stromal tissue samples were collected by laser capture microdissection from 10 patients with normal BE and 13 patients with high-grade dysplastic/EAC. Samples were analyzed by mass spectrometry-based proteomic analysis. Expressed proteins were determined by label-free quantitation, and gene set enrichment was used to find differentially expressed pathways. The results were validated by immunohistochemistry for two selected key proteins (MSH6 and XPO5).

RESULTS

Comparing dysplastic/EAC to non-dysplastic BE, we found in equal volumes of epithelial tissue an overall up-regulation in terms of protein abundance and diversity, and determined a set of 226 differentially expressed proteins. Significantly higher expressions of MSH6 and XPO5 were validated orthogonally and confirmed by immunohistochemistry.

CONCLUSIONS

Our results demonstrate that disease-related proteomic alterations can be determined by analyzing minute amounts of cell-type-specific collected tissue. Further analysis indicated that alterations of certain pathways associated with carcinogenesis, such as micro-RNA trafficking, DNA damage repair, and spliceosome activity, exist in dysplastic/EAC.

Notch Signaling Mediates Differentiation in Barrett's Esophagus and Promotes Progression to Adenocarcinoma

BACKGROUND & AIMS

Studies are needed to determine the mechanism by which Barrett's esophagus (BE) progresses to esophageal adenocarcinoma (EAC). Notch signaling maintains stem cells in the gastrointestinal tract and is dysregulated during carcinogenesis. We explored the relationship between Notch signaling and goblet cell maturation, a feature of BE, during EAC pathogenesis.

METHODS

We measured goblet cell density and levels of Notch messenger RNAs in BE tissues from 164 patients, with and without dysplasia or EAC, enrolled in a multicenter study. We analyzed the effects of conditional expression of an activated form of NOTCH2 (pL2.Lgr5.N2IC), conditional deletion of NOTCH2 (pL2.Lgr5.N2fl/fl), or loss of nuclear factor κB (NF-κB) (pL2.Lgr5.p65fl/fl), in Lgr5+ (progenitor) cells in L2-IL1B mice (which overexpress interleukin 1 beta in esophagus and squamous forestomach and are used as a model of BE). We collected esophageal and stomach tissues and performed histology, immunohistochemistry, flow cytometry, transcriptome, and real-time polymerase chain reaction analyses. Cardia and forestomach tissues from mice were cultured as organoids and incubated with inhibitors of Notch or NF-kB.

RESULTS

Progression of BE to EAC was associated with a significant reduction in goblet cell density comparing nondysplastic regions of tissues from patients; there was an inverse correlation between goblet cell density and levels of NOTCH3 and JAG2 messenger RNA. In mice, expression of the activated intracellular form of NOTCH2 in Lgr5+ cells reduced goblet-like cell maturation, increased crypt fission, and accelerated the development of tumors in the squamocolumnar junction. Mice with deletion of NOTCH2 from Lgr5+ cells had increased maturation of goblet-like cells, reduced crypt fission, and developed fewer tumors. Esophageal tissues from in pL2.Lgr5.N2IC mice had increased levels of RelA (which encodes the p65 unit of NF-κB) compared to tissues from L2-IL1B mice, and we found evidence of increased NF-κB activity in Lgr5+ cells. Esophageal tissues from pL2.Lgr5.p65fl/fl mice had lower inflammation and metaplasia scores than pL2.Lgr5.N2IC mice. In organoids derived from pL2-IL1B mice, the NF-κB inhibitor JSH-23 reduced cell survival and proliferation.

CONCLUSIONS

Notch signaling contributes to activation of NF-κB and regulates differentiation of gastric cardia progenitor cells in a mouse model of BE. In human esophageal tissues, progression of BE to EAC was associated with reduced goblet cell density and increased levels of Notch expression. Strategies to block this pathway might be developed to prevent EAC in patients with BE.

Characterizing caspase-1 involvement during esophageal disease progression

Barrett's esophagus (BE) is an inflammatory condition and a neoplastic precursor to esophageal adenocarcinoma (EAC). Inflammasome signaling, which contributes to acute and chronic inflammation, results in caspase-1 activation leading to the secretion of IL-1β and IL-18, and inflammatory cell death (pyroptosis). This study aimed to characterize caspase-1 expression, and its functional importance, during disease progression to BE and EAC. Three models of disease progression (Normal-BE-EAC) were employed to profile caspase-1 expression: (1) a human esophageal cell line model; (2) a murine model of BE; and (3) resected tissue from BE-associated EAC patients. BE patient biopsies and murine BE organoids were cultured ex vivo in the presence of a caspase-1 inhibitor, to determine the importance of caspase-1 for inflammatory cytokine and chemokine secretion.Epithelial caspase-1 expression levels were significantly enhanced in BE (p < 0.01). In contrast, stromal caspase-1 levels correlated with histological inflammation scores during disease progression (p < 0.05). Elevated secretion of IL-1β from BE explanted tissue, compared to adjacent normal tissue (p < 0.01), confirmed enhanced activity of caspase-1 in BE tissue. Caspase-1 inhibition in LPS-stimulated murine BE organoids caused a significant reduction in IL-1β (p < 0.01) and CXCL1 (p < 0.05) secretion, confirming the importance of caspase-1 in the production of cytokines and chemokines associated with disease progression from BE to EAC. Targeting caspase-1 activity in BE patients should therefore be tested as a novel strategy to prevent inflammatory complications associated with disease progression.

DCLK1 inhibition attenuates tumorigenesis and improves chemosensitivity in esophageal squamous cell carcinoma by inhibiting β-catenin/c-Myc signaling

Doublecortin-like kinase 1 (DCLK1) is involved in tumorigenesis, tumor growth and metastasis, and epithelial-to-mesenchymal transition in many digestive tract tumors. It is reportedly highly expressed in Barrett's esophagus and esophageal adenocarcinoma, but its effects on the occurrence and progression of esophageal squamous cell carcinoma (ESCC) remain unclear. In this study, real-time PCR and western blot analysis confirmed significant upregulation of DCLK1 expression in human ESCC tissues and cell lines. CCK-8 assay showed that transfection with siRNA against DCLK1 (si-DCLK1) markedly inhibited cell proliferation and colony formation in the ESCC cell lines Eca109 and TE1. Transwell assay revealed that si-DCLK1 transfection inhibited the migratory and invasive capacities of Eca109 and TE1 cells. Moreover, si-DCLK1 increased the chemosensitivity of these cells to cisplatin, as indicated by inhibited cell viability and colony formation, and increased ROS and apoptosis in cisplatin-treated cells. Western blot assay revealed that expression of nuclear β-catenin and c-Myc was significantly increased in ESCC tissues and that si-DCLK1 markedly downregulated nuclear β-catenin and c-Myc in Eca109 cells. Treatment with lithium chloride, an activator of β-catenin signaling, partially abolished the si-DCLK1-induced inhibition of proliferation, migration, invasion, and chemoresistance of ESCC cells. These findings suggest that knockdown of DCLK1 may inhibit the progression of ESCC by regulating proliferation, migration, invasion, and chemosensitivity via suppressing the β-catenin/c-Myc pathway, supporting a promising therapeutic target against ESCC.

Columnar metaplasia and Barrett’s esophagus: morphological heterogeneity and immunohistochemical phenotype

Barrett’s esophagus (BE) is a pathologically confirmed intestinal metaplasia (CM) of the distal esophagus. BE is recognized as a potential complication of gastroesophageal reflux disease (GERD) and a premalignant condition with a high risk of neoplastic progression. The aim of this study was to compare the morphology of biopsied BE segments and CM segments extending < 1 cm and > 1 cm above the gastroesophageal junction (GEJ), as well as to perform the immunohistochemical analysis of biopsies with BE and CM > 1 cm above GEJ with or without dysplasia. The study recruited 92 patients with GERD: 42 patients with BE, 24 patients with CM > 1 cm above GEJ (С0М1.5–С13M14) and 26 patients with CM < 1 cm above GEJ (С0М0.3–0.8). Comparative analysis of tissue morphology revealed an association between the reactive changes in the epithelium and the severity of esophagitis in all groups. Reactive changes were detected significantly more often in BE segments than in CM segments > 1 cm (Mann-Whitney U, p < 0.05). Eight patients with BE (19.05%) were found to have low-grade dysplasia. One patient with CM > 1 cm above GEJ (4.2%) had high-grade dysplasia with cardiac-type metaplasia and immunohistochemical features of submorphological enteralization. Immunohistochemical testing for the intestinal and gastric markers of cell differentiation revealed the signs of submorphological enteralisation in all esophageal specimens with cardiac and fundic type metaplasia and in the specimens with BE in the areas lacking goblet cells.

Origins of Metaplasia in the Esophagus: Is This a GE Junction Stem Cell Disease?

The incidence of esophageal adenocarcinoma (EAC) and its precursor lesion Barrett's esophagus (BE) has been increasing steadily in the western world in recent decades. Understanding the cellular origins of BE and the conditions responsible for their malignant transformation would greatly facilitate risk assessment and identification of patients at risk of progression, but this topic remains a source of debate. Here, we review recent findings that have provided support for the gastroesophageal junction (GEJ) as the main source of stem cells that give rise to BE and EAC. These include both gastric cardia cells and transitional basal cells. Furthermore, we discuss the role of chronic injury and inflammation in a tumor microenvironment as a major factor in promoting stem cell expansion and proliferation as well as transformation of the GEJ-derived stem cells and progression to EAC. We conclude that there exists a large amount of empirical support for the GEJ as the likely source of BE stem cells. While BE seems to resemble a successful adaptation to esophageal damage, carcinogenesis appears as a consequence of natural selection at the level of GEJ stem cells, and later glands, that expand into the esophagus wherein the local ecology creates the selective landscape for cancer progression.

The metaplastic mosaic of Barrett's oesophagus

Barrett's oesophagus surveillance biopsies represent a significant share of the daily workload for a busy histopathology department. Given the emphasis on endoscopic detection and dysplasia grading, it is easy to forget that the benefits of these screening programs remain unproven. The majority of patients are at low risk of progression to oesophageal adenocarcinoma, and periodic surveillance of these patients is burdensome and costly. Here, we investigate the parallels in the development of Barrett's oesophagus and other scenarios of wound healing in the intestine. There is now increased recognition of the full range of glandular phenotypes that can be found in patients' surveillance biopsies, and emerging evidence suggests parallel pathways to oesophageal adenocarcinoma. Greater understanding of the conditions that favour progression to cancer in the distal oesophagus will allow us to focus resources on patients at increased risk.

Esophageal Cancer: Genomic and Molecular Characterization, Stem Cell Compartment and Clonal Evolution

Esophageal cancer (EC) is the eighth most common cancer and is the sixth leading cause of death worldwide. The incidence of histologic subtypes of EC, esophageal adenocarcinoma (EAC) and esophageal squamous carcinoma (ESCC), display considerable geographic variation. EAC arises from metaplastic Barrett's esophagus (BE) in the context of chronic inflammation secondary to exposure to acid and bile. The main risk factors for developing ESCC are cigarette smoking and alcohol consumption. The main somatic genetic abnormalities showed a different genetic landscape in EAC compared to ESCC. EAC is a heterogeneous cancer dominated by copy number alterations, a high mutational burden, co-amplification of receptor tyrosine kinase, frequent TP53 mutations. The cellular origins of BE and EAC are still not understood: animal models supported a cellular origin either from stem cells located in the basal layer of esophageal epithelium or from progenitors present in the cardia region. Many studies support the existence of cancer stem cells (CSCs) able to initiate and maintain EAC or ESCC. The exact identification of these CSCs, as well as their role in the pathogenesis of EAC and ESCC remain still to be demonstrated. The reviewed studies suggest that current molecular and cellular characterization of EAC and ESCC should serve as background for development of new treatment strategies.