The Role of Acid Suppression in Barrett's Esophagus

The Role of PARP ‐1 and NF‐κB in Bile‐Induced DNA Damage and Oncogenic Profile in Hypopharyngeal Cells

OBJECTIVES/HYPOTHESIS

We recently documented that acidic bile, a gastroesophageal reflux content, can cause invasive hypopharyngeal squamous cell carcinoma, by inducing widespread DNA damage and promoting nuclear factor kappa B (NF-κB)-related oncogenic molecular events. Poly or adenosine diphosphate (ADP)-ribose polymerase-1 (PARP-1), a sensitive sensor of DNA damage, may interact with NF-κB. We hypothesized that PARP-1 is activated in hypopharyngeal cells (HCs) with marked DNA damage caused by acidic bile, hence there is an association between PARP-1 and NF-κB activation or its related oncogenic profile, in this process.

STUDY DESIGN

In vitro study.

METHODS

We targeted PARP-1 and NF-κB(p65), using pharmacologic inhibitors, 1.0 μM Rucaparib (AG014699) and 10 μM BAY 11-7082 {3-[4=methylphenyl)sulfonyl]-(2E)-propenenitrile}, respectively, or silencing their gene expression (siRNAs) and used immunofluorescence, luciferase, cell viability, direct enzyme-linked immunosorbent assays, and qPCR analysis to detect the effect of targeting PARP-1 or NF-κB in acidic bile-induced DNA damage, PARP-1, p-NF-κB, and B-cell lymphoma 2 (Bcl-2) expression, as well as NF-κB transcriptional activity, cell survival, and mRNA oncogenic phenotype in HCs.

RESULTS

We showed that (i) PARP-1 is overexpressed by acidic bile, (ii) targeting NF-κB adequately prevents the acidic bile-induced DNA double-strand breaks (DSBs) by gamma H2A histone family member X (γH2AX), oxidative DNA/RNA damage, PARP-1 overexpression, anti-apoptotic mRNA phenotype, and cell survival, whereas (iii) targeting PARP-1 preserves elevated DNA damage, NF-κB activation, and anti-apoptotic phenotype.

CONCLUSION

We document for the first time that the activation of PARP-1 is an early event during bile reflux-related head and neck carcinogenesis and that NF-κB can mediate DNA damage and PARP-1 activation. Our data encourage further investigation into how acidic bile-induced activated NF-κB mediates DNA damage in hypopharyngeal carcinogenesis.

LEVEL OF EVIDENCE

NA Laryngoscope, 133:1146-1155, 2023.

Proton pump inhibitors may reduce the risk of high-grade dysplasia and/or esophageal adenocarcinoma in Barrett's esophagus: a systematic review and meta-analysis

BACKGROUND

Barrett's esophagus (BE) is an important risk factor for high-grade dysplasia (HGD) and/or esophageal adenocarcinoma (EAC). The effect of proton pump inhibitors (PPIs) on the chemoprevention of HGD and/or EAC arising from BE remains controversial.

RESEARCH DESIGN AND METHODS

PubMed, EMBASE, and Cochrane Library databases were systematically searched. Risk ratios (RRs) or odds ratios (ORs) with 95% confidence intervals (CIs) were pooled by a random-effect model. Heterogeneity and its potential source were assessed.

RESULTS

Fifteen studies with 26,291 BE patients were included. Meta-analysis of eight cohort studies showed that PPIs can significantly reduce the risk of HGD and/or EAC in BE patients (RR = 0.46; P < 0.001), but meta-analysis of six case-control studies showed no significant benefit of PPIs (OR = 0.64; P = 0.334). Heterogeneity was significant among both cohort and case-control studies, which might be attributed to the information sources of PPIs. There was no significant protective effect of high-dose PPIs on HGD and/or EAC in one RCT (RR = 0.84; P = 0.21), meta-analysis of two cohort studies (RR = 0.61; P = 0.28), or meta-analysis of two case-control studies (OR = 0.32; P = 0.08).

CONCLUSIONS

Chemoprevention of HGD and/or EAC by PPIs may be considered in BE patients. However, there might not be further preventive effect of high-dose PPIs.

Nrf2/Keap1-Pathway Activation and Reduced Susceptibility to Chemotherapy Treatment by Acidification in Esophageal Adenocarcinoma Cells

Simple Summary

Inflammation caused by acidic reflux contributes to disease progression in Barrett’s esophagus. Little is known, whether esophageal cancer cells are influenced by acidic reflux and whether reflux influences cancer cell physiology, targeting the Nrf2/Kepa1- and the NFκB-pathway. The understanding mechanisms of the acidic susceptibility in cells from advanced stages of Barrett’s esophagus will provide further evidence, whether it should be prevented during chemotherapy for EAC treatment.

Abstract

Chronic acid reflux causes cellular damage and inflammation in the lower esophagus. Due to these irritating insults, the squamous epithelium is replaced by metaplastic epithelium, which is a risk factor for the development of esophageal adenocarcinoma (EAC). In this study, we investigated the acid susceptibility in a Barrett’s cell culture in vitro model, using six cell lines, derived from squamous epithelium (EPC1 and EPC2), metaplasia (CP-A), dysplasia (CP-B), and EAC (OE33 and OE19) cells. Cells exposed to acidic pH showed a decreased viability dependent on time, pH, and progression status in the Barrett’s sequence, with the highest acid susceptibility in the squamous epithelium (EPC1 and EPC2), and the lowest in EAC cells. Acid pulsing was accompanied with an activation of the Nrf2/Keap1- and the NFκB-pathway, resulting in an increased expression of HO1—independent of the cellular context. OE33 showed a decreased responsiveness towards 5-FU, when the cells were grown in acidic conditions (pH 6 and pH 5.5). Our findings suggest a strong damage of squamous epithelium by gastroesophageal reflux, while Barrett’s dysplasia and EAC cells apparently exert acid-protective features, which lead to a cellular resistance against acid reflux.

Microbiota Detection Patterns Correlate With Presence and Severity of Barrett's Esophagus

Background

The microbiome has been increasingly associated with different disease processes, but its role in esophagus is largely unknown. Our goal was to determine the associations of the esophageal microbiota with Barrett’s esophagus.

Methods

A total of 74 patients were included in this prospective study, including 34 patients with Barrett’s esophagus and 40 patients without Barrett’s esophagus. Esophageal swabs were obtained from the uvula, and mucosal biopsies were obtained from the proximal esophagus and distal esophagus in each patient. The microbiome of each sample was assessed using a customized Esophageal Microbiome qPCR array (EMB). For each clinical sample, we completed a detection/non-detection analysis for each organism in the EMB. The limit of detection (LOD) for each target was established by analysis of plasmid dilutions.

Results

Average age was 60.2 years. There were significantly different microbial detection patterns in patients with Barrett’s esophagus compared to the control population. There were a greater number of organisms which had different likelihoods of detection in the distal esophagus, compared to the proximal esophagus or uvula. In addition, as the length of the Barrett’s column increased, multiple organisms were less likely to be detected. This decreased likelihood occurred only in the distal esophagus. Beside Barrett’s esophagus, no other demographic factors were associated with differences in detection patterns.

Conclusions

Microbial community structures differ between patients with and without Barrett’s esophagus. Certain organisms are less likely to be detected as the severity of Barrett’s esophagus worsens. These results suggest that particular organisms may have a protective effect against the development of Barrett’s esophagus.

Novel Ex Vivo Model to Examine the Mechanism and Relationship of Esophageal Microbiota and Disease

Rates of esophageal cancer have increased over the last 40 years. Recent clinical research has identified correlations between the esophageal microbiome and disease. However, mechanisms of action have been difficult to elucidate performing human experimentation. We propose an ex vivo model, which mimics the esophagus and is ideal for mechanistic studies on the esophageal microbiome and resultant transcriptome. To determine the microbiome and transcriptome profile of the human distal esophagus, the microbiome was assessed in 74 patients and the transcriptome profile was assessed in 37 patients with and without Barrett’s esophagus. Thereafter, an ex vivo model of the esophagus was created using an air–liquid interfaced (ALI) design. This design created a sterile apical surface and a nutrient-rich basal surface. An epithelial layer was grown on the apical surface. A normal microbiome and Barrett’s microbiome was harvested and created from patients during endoscopic examination of the esophagus. There was a distinct microbiome in patients with Barrett’s esophagus. The ex vivo model was successfully created with a squamous epithelial layer on the apical surface of the ex vivo system. Using this ex vivo model, multiple normal esophageal and Barrett’s esophageal cell lines will be created and used for experimentation. Each microbiome will be inoculated onto the sterile apical surface of each cell line. The resultant microbiome and transcriptome profile on each surface will be measured and compared to results in the human esophagus to determine the mechanism of the microbiome interaction.

Association of Common Use Pharmaceuticals in Reducing Risk of Esophageal Adenocarcinoma: A SEER-Medicare Analysis

Barrett's esophagus (BE), a recognized risk factor for esophageal adenocarcinoma (EAC), is routinely managed with proton pump inhibitors (PPIs) when symptomatic. Several lines of evidence suggest that PPIs may prevent malignant transformation. Chronic use of other common drugs, namely, statins nonsteroidal anti-inflammatory drugs (NSAIDs) and metformin, may also interfere with BE carcinogenesis, but confirmatory evidence is lacking. We identified 1,943 EAC cases and 19,430 controls (matched 10:1) between 2007 and 2013 that met our specified inclusion criteria in the SEER-Medicare database. Conditional logistic regression was used to generate odds ratios (OR) and 95% confidence intervals (95% CI). Wald χ² tests were used to assess significance of covariates. Compared with controls, EAC cases had a higher prevalence of BE (26.2%). Use of PPIs, NSAIDs, statins, or metformin reduced the odds of EAC (PPIs: 0.10; 95% CI, 0.09-0.12; NSAIDs: 0.62; 95% CI, 0.51-0.74; statins: 0.15; 95% CI, 0.13-0.17; metformin: 0.76; 95% CI, 0.62-0.93). When stratified by BE, these associations persisted, though no association was found between NSAID use and EAC risk for participants with BE. Dual use of PPIs with NSAIDs or statins, and NSAID, statin, or metformin use alone also showed significant EAC risk reduction among all participants and those without BE. Use of PPIs alone and with NSAIDs, statins, or metformin was associated with reduced risk of EAC; however, a history of BE may diminish drug efficacy. These results indicate that common pharmacologic agents alone or in combination may decrease EAC development.Prevention Relevance: The use of common drugs, such as proton pump inhibitors, statins, non-steroidal anti-inflammatory drugs, or metformin, may reduce one's risk of developing esophageal adenocarcinoma. These results suggest that repurposing agents often used for common chronic conditions may be a new strategy for cancer prevention efforts.

Adversarial convolutional network for esophageal tissue segmentation on OCT images

Automatic segmentation is important for esophageal OCT image processing, which is able to provide tissue characteristics such as shape and thickness for disease diagnosis. Existing automatical segmentation methods based on deep convolutional networks may not generate accurate segmentation results due to limited training set and various layer shapes. This study proposed a novel adversarial convolutional network (ACN) to segment esophageal OCT images using a convolutional network trained by adversarial learning. The proposed framework includes a generator and a discriminator, both with U-Net alike fully convolutional architecture. The discriminator is a hybrid network that discriminates whether the generated results are real and implements pixel classification at the same time. Leveraging on the adversarial training, the discriminator becomes more powerful. In addition, the adversarial loss is able to encode high order relationships of pixels, thus eliminating the requirements of post-processing. Experiments on segmenting esophageal OCT images from guinea pigs confirmed that the ACN outperforms several deep learning frameworks in pixel classification accuracy and improves the segmentation result. The potential clinical application of ACN for detecting eosinophilic esophagitis (EoE), an esophageal disease, is also presented in the experiment.

The role of bile reflux and its related NF-κB activated pathway in progression of hypopharyngeal squamous cell cancer

BACKGROUND

Prognosis for hypopharyngeal cancer is usually poor, and recurrence is common. Identifying new factors or related mechanisms that promote its progression may have clinical implications. Although, recent studies support bile reflux in hypopharyngeal carcinogenesis, it remains to be explored how bile and its related NF-κB activated pathway may further affects its progression in already established hypopharyngeal cancer.

METHODS

Hypopharyngeal squamous cell carcinoma (HSCC) cell lines, FaDu and UMSCC11A, both negative for HPV, were repetitively exposed to bile acids (400 μM) at variable pH points (4.0, 5.5 and 7.0). Immunofluorescence, western blotting, luciferase assay, and qPCR were used to detect NF-κB activation, bcl-2 overexpression and gene expression.

RESULTS

Bile at strongly acidic pH (4.0) potentiated the activation of NF-κB and its related mRNA phenotype in HSCC cells. IL-6, TNF-α, and BCL2 were found among the highest overexpressed genes as was previously found in HSCCs excised from patients with documented biliary reflux. An enhanced transcriptional activity of EGFR, RELA, STAT3, and WNT5Α and higher survival rates were observed in HSCC cells exposed to acidic bile compared to those exposed to bile at weakly acidic or neutral pH.

CONCLUSION

Our novel findings support the observation that bile reflux has the potential for actively influencing the progression of hypopharyngeal cancer, mediated by NF-κB. In patients with hypopharyngeal cancer and known gastroesophageal reflux disease, antacid therapy may exert a role in furthering control of disease recurrence and progression.

Recent advances in Barrett's esophagus

Barrett's esophagus (BE) is the only known precursor of esophageal adenocarcinoma, one of the few cancers with increasing incidence in developed countries. The pathogenesis of BE is unclear with regard to either the cellular origin of this metaplastic epithelium or the manner in which malignant transformation occurs, although recent data indicate a possible junctional origin of stem cells for BE. Treatment of BE may be achieved using endoscopic eradication therapy; however, there is a lack of discriminatory tools to identify individuals at sufficient risk for cancer development in whom intervention is warranted. Reduction in gastroesophageal reflux of gastric contents including acid is mandatory to achieve remission from BE after endoscopic ablation, and can be achieved using medical or nonmedical interventions. Research topics of greatest interest include the mechanism of BE development and transformation to cancer, risk stratification methods to identify individuals who may benefit from ablation of BE, optimization of eradication therapy, and surveillance methods to ensure that remission is maintained after eradication is achieved.