Duodenal Reflux Leads to Down Regulation of DNA Mismatch Repair Pathway in an Animal Model of Esophageal Cancer

Pan-cancer landscape of abnormal ctDNA methylation across human tumors

BACKGROUND

The aim of this paper is to explore the correlation between circulating tumor DNA (ctDNA) methylation and mutations and its value in clinical early cancer screening.

METHODS

We performed target region methylation sequencing and genome sequencing on plasma samples. Methylation models to distinguish cancer from healthy individuals have been developed using hypermethylated genes in tumors and validated in training set and prediction set.

RESULTS

We found that patients with cancer had higher levels of ctDNA methylation compared to healthy individuals. The level of ctDNA methylation in cell cycle, p53, Notch pathway in pan-cancer was significantly correlated with the number of mutations, and mutation frequency. Methylation burden in some tumors was significantly correlated with tumor mutational burden (TMB), microsatellite instability (MSI) and PD-L1. The ctDNA methylation differences in cancer patients were mainly concentrated in the Herpes simplex virus 1 infection pathway. The area under curve (AUC) of the training and prediction sets of the methylation model distinguishing cancer from healthy individuals were 0.93 and 0.92, respectively.

CONCLUSION

Our study provides a landscape of methylation levels of important pathways in pan-cancer. ctDNA methylation significantly correlates with mutation type, frequency and number, providing a reference for clinical application of ctDNA methylation in early cancer screening.

Potential Role of Silencing Ribonucleic Acid for Esophageal Cancer Treatment

INTRODUCTION

Esophageal cancer is an aggressive malignancy with high mortality. Optimal treatment of esophageal cancer remains an elusive goal. Ribonucleic acid (RNA) interference is a novel potential targeted approach to treat esophageal cancer. Targeting oncogenes that can alter critical cellular functions with silencing RNA molecules is a promising approach. The silencing of specific oncogenes in esophageal cancer cells in the experimental setting has been shown to decrease the expression of oncogenic proteins. This has resulted in cell apoptosis, reduction in cell proliferation, reduced invasion, migration, epithelial-mesenchymal transition, decrease in tumor angiogenesis and metastasis, and overcoming drug resistance. The Hedgehog (Hh) signaling pathway has been shown to be involved in esophageal adenocarcinoma formation in a reflux animal model. In addition to Hh, we will focus on other targets with clinical potential in the treatment of esophageal cancer.

MATERIALS AND METHODS

We searched for articles published from 2005 to August 2020 that studied the siRNA effects on inhibiting esophageal cancer formation in experimental settings. We used combinations of the following terms for searching: "esophageal cancer," "RNA interference," "small interfering RNA," "siRNA," "silencing RNA," "Smoothened (Smo)," "Gli," "Bcl-2," "Bcl-XL," "Bcl-W,″ "Mcl-1," "Bfl-1," "STAT3,"and "Hypoxia inducible factor (HIF)". A total of 21 relevant articles were found.

RESULTS AND CONCLUSIONS

Several proto-oncogenes/oncogenes including Hh pathway mediators, glioma-associated oncogene homolog 1 (Gli-1), Smoothened (Smo), and antiapoptotic Bcl-2 have potential as targets for silencing RNA in the treatment of esophageal cancer.

Targeting the Hedgehog Pathway Using Itraconazole to Prevent Progression of Barrett's Esophagus to Invasive Esophageal Adenocarcinoma

OBJECTIVE

The aim of the study was to investigate whether inhibition of Sonic Hedgehog (SHH) pathway would prevent progression of Barrett's Esophagus (BE) to esophageal adenocarcinoma.

BACKGROUND

The hedgehog signaling pathway is a leading candidate as a molecular mediator of BE and esophageal adenocarcinoma (EAC). Repurposed use of existing off-patent, safe and tolerable drugs that can inhibit hedgehog, such as itraconazole, could prevent progression of BE to EAC.

METHODS

The efficacy of itraconazole was investigated using a surgical rat reflux model of Barrett's Metaplasia (BM). Weekly intraperitoneal injections of saline (control group) or itraconazole (treatment group; 200 mg/kg) were started at 24 weeks postsurgery. Esophageal tissue was harvested at 40 weeks. The role of the Hh pathway was also evaluated clinically. Esophageal tissue was harvested after 40 weeks for pathological examination and evaluation of the SHH pathway by immunohistochemistry.

RESULTS

BM was present in control animals 29 of 31 (93%) versus itraconazole 22 of 24 (91%). EAC was significantly lower in itraconazole 2 of 24 (8%) versus control 10 of 31 (32%), respectively (P = 0.033). Esophageal SHH levels were lower in itraconazole vs control (P = 0.12). In esophageal tissue from humans with recurrent or persistent dysplastic BE within 24 months of ablative treatment, strong SHH and Indian Hedgehog expression occurred in distal BE versus proximal squamous epithelium, odds ratio = 6.1 (95% confidence interval: 1.6, 23.4) and odds ratio = 6.4 (95% confidence interval: 1.2, 32.8), respectively.

CONCLUSION

Itraconazole significantly decreases EAC development and SHH expression in a preclinical animal model of BM. In humans, BE tissue expresses higher SHH, Indian Hedgehog, and bone morphogenic protein levels than normal squamous esophageal epithelium.

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.

Diagnostic correlation between the expression of the DNA repair enzyme N-methylpurine DNA glycosylase and esophageal adenocarcinoma onset: a retrospective pilot study

EAC in its early stages, when it can potentially be cured, is rarely symptomatic and is associated with high mortality rates because in part of late-stage diagnosis. Given that DNA repair is an important contributory factor of early-stage malignancy, our study focused on the expression of the base excision repair enzyme N-methylpurine DNA glycosylase (MPG) in EAC disease onset. MPG messenger RNA (mRNA) expression levels were determined using quantitative reverse transcriptase polymerase chain reaction from a maximum of 72 patient samples. Immunohistochemistry was further utilized for the detection of MPG protein, and semiquantitative analysis performed using an H-score approach was carried out on a total of 130 archival tissue samples of different esophageal pathologies. Nuclear localized MPG protein was detected in all nonmalignant tissues derived from the enterohepatic system, with H-score values of 3.9-5.5 ± 0.4-1.0. In cancerous tissues derived from the enterohepatic system, a 9.5-fold increase in the level of MPG mRNA expression was specifically observed in the malignant regions located within the esophagus region. Further analysis revealed a 9- and 14-fold increase in MPG mRNA expression in EAC tumor, node, metastasis stages II and III, respectively, suggesting MPG expression to correlate with EAC disease progression. Immunohistochemistry analysis further showed a sevenfold significant increase in MPG protein expression in EAC tissues. Intriguingly, there was a fivefold significant decrease in nuclear localized MPG protein expression in tissues derived from Barrett's esophagus and low-grade dysplasia. Such findings highlight a complex regulatory pattern governing DNA glycosylase base excision repair initiation, as normal tissue undergoes Barrett's metaplasia and later dedifferentiates to EAC. Indeed, disease-stage-specific alterations in the expression of MPG may highlight a potential role for MPG in determining EAC onset and thus potentially be of clinical relevance for early disease detection and increased patient survival.

Effect of hOGG1 over-expression on cisplatin resistance in esophageal squamous carcinoma cells

PURPOSE

Human 8-oxoguanine DNA glycosylase (hOGG1) is an ubiquitous protein. It initiates the DNA base excision repair (BER) pathway to repair the 8-oxoguanine lesion. This may be associated with chemotherapeutics. In this article, the effect of hOGG1 over-expression on cisplatin resistance in esophageal squamous cell carcinoma (ESCC) EC9706 and ET13 cells was investigated.

METHODS

Recombinant adenovirus pAd/CMV/V5-DEST-hogg1 and control adenovirus pAd/CMV/5-GW/lacZ were constructed and transferred into EC9706 and ET13 cells, respectively. The protein expression and localization were determined by Western blot and by immunofluorescence assay. The cell growth viability was determined by 3-(4,5-dimethylthiazol-2yl)-2,5 diphe-nyltetrazolium bromide (MTT) assay and clonogenic survival assay. The apoptotic cells were detected by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) staining and flow cytometry. The oxidative DNA damage (8-Hydroxyguanine [8-oxoG] DNA level) was semi-quantified by immunohistochemistry assay.

RESULTS

The over-expression of hOGG1 protein was mainly in the nucleus in hOGG1 cells. After exposure to a common chemotherapeutic agent cisplatin, hOGG1 over-expression cells exhibited longer survival ability, lower cell apoptosis, and less 8-oxoG oxidative damage, compared with vector-treated cells and no-treated cells (p<0.05).

CONCLUSION

BER pathway to repair 8-oxoG lesion may be associated with ESCC sensitivity to cisplatin, and over-expression of hOGG1 in the nucleus can repair more 8-oxoG oxidative damage. The findings implied that over-expression of hOGG1 can protect ESCC cells from cisplatin-induced apoptosis and prolong cancer cell survival time. Modulation of DNA damage repair activity in the nucleus or in the mitochondria may lead to a different approach regarding cisplatin-induced resistance to chemotherapy.

The severity of duodeno-esophageal reflux influences the development of different histological types of esophageal cancer in a rat model

The mechanism through which each histological type of carcinoma arises from the esophageal mucosa remains unknown. This study was designed to investigate whether there is an association between the severity of duodeno-esophageal reflux and the histological type of esophageal cancer. A series of 120 male Fischer rats, weighing ∼180 g, were randomized to receive one of the following procedures: duodeno-forestomach reflux (DFR) with reduced exposure to duodenal contents, duodeno-esophageal reflux (DER) with increased exposure to duodenal contents and three control operations (DFR, DER control and sham). The reflux of bile was estimated with (99m)Tc-PMT scintigraphy. All animals were fed a standard diet without carcinogen. The esophageal mucosa was assessed 50 weeks after surgery for carcinoma. The median scanned fraction rate of duodeno-esophageal reflux was significantly lower for the rodents in the DFR group than those in the DER group. Five of 28 rodents in the DFR group and 17 of the 22 rodents in the DER group developed esophageal carcinoma. None of the controls developed carcinoma. The five rodents in the DFR group developed SCC. Of 22 esophageal carcinomas for the DER group, nine were SCC, 12 ADC and one was adenosquamous carcinoma. The fraction of esophageal SCC for the DFR group was significantly higher than that for the DER group, while the fraction of esophageal ADC for the DFR group was significantly lower than that for the DER group. These observations suggest that the severity of duodeno-esophageal reflux in rodents is related to the development of different histological types of esophageal carcinoma.

Expression and clinical significance of the DNA repair enzyme MYH in esophageal squamous cell carcinoma

MYH is an important enzyme in combating DNA oxidative stress in the occurrence and development of various types of tumors. To investigate the correlation between expression of the DNA repair enzyme MYH in esophageal squamous cell carcinoma and 8-oxoguanine (8-oxoG) oxidative damage, as well as the clinical significance of altered MYH expression, tissues from 175 esophageal carcinoma cases were investigated in the present study. MYH expression and 8-oxoG oxidative damage in squamous cell carcinoma and adjacent normal tissue were assessed by immunohistochemistry and Western blotting. In 82.9% (145/175) of the cases, MYH protein expression in esophageal squamous cell carcinoma was lower than that of adjacent normal tissue (t=4.24, P<0.001). Additionally, 8-oxoG staining was higher in the tumors than in the normal tissue. Lower expression of MYH in esophageal squamous cell carcinoma was associated with depth of invasion, venous invasion, TNM stage and lymph node metastasis (P<0.05). In conclusion, a lower MYH expression level in esophageal cell carcinoma tissue was inversely associated with more severe 8-oxoG oxidative damage, suggesting that changes in MYH activity correspond to increased DNA damage in tumor cells. The use of MYH expression as a postoperative index for esophageal squamous cell carcinoma may guide the formulation of individualized chemotherapy for patients after surgery.

Inflammation and Barrett's carcinogenesis

Barrett's esophagus (BE) is one of the most common premalignant lesions in which normal squamous epithelium of the esophagus is replaced by metaplastic columnar epithelium. Esophageal adenocarcinoma (EA) develops through progression from BE to low- and high-grade dysplasia (LGD/HGD) and to adenocarcinoma. It is widely accepted that inflammation can increase cancer risk, promoting tumor progression. Therefore, inflammation is regarded as the seventh hallmark of cancer. In recent years, the inflammation-cancer connection of Barrett's carcinogenesis has been intensively studied, unraveling genetic abnormalities. Besides genetic alterations, inflammation is also epigenetically linked to loss of protein expression through transcriptional silencing via promoter methylation. Key mediators linking inflammation and Barrett's carcinogenesis include reactive oxygen species (ROS), NFκB, inflammatory cytokines, prostaglandins, and specific microRNAs (miRNAs). Therefore, the decipherment of molecular pathways that contain these and novel inflammatory key mediators is of major importance for diagnosis, therapy, and prognosis. The detailed elucidation of the signaling molecules involved in Barrett's carcinogenesis will be important for the development of pharmaceutical inhibitors. We herein give an overview of the current knowledge of the inflammation-mediated genetic and epigenetic alterations involved in Barrett's carcinogenesis. We highlight the role of oxidative stress and deregulated DNA damage checkpoints besides the NFκB pathway.

Effect of low-proof alcoholic beverages on duodenogastro-esophageal reflux in health and GERD

BACKGROUND

Alcoholic beverages are known to increase acidic gastro-esophageal reflux (GER) and the risk of esophagitis. Moreover, duodenogastro-esophageal reflux (DGER), containing bile acids, was shown to harmfully alter the esophageal mucosa, alone and synergistically with HCl and pepsin. However, studies directly addressing potential effects of different low proof alcoholic beverages on DGER in health and disease are missing.

METHODS

Bilitec readings for beer and white, rose, and red wine were obtained in vitro from pure and from mixtures with bile. One-hour DGER monitoring and pH-metry were performed in 12 healthy subjects and nine reflux patients with DGER after ingestion of a standardized liquid meal together with 300 mL of water, white wine, and in the volunteers, beer and rose wine.

KEY RESULTS

Bilitec measurement was found to be feasible in the presence of beer, white wine, and using a threshold of 0.25, rose wine. However, the presence of red wine resulted in extinction values above this threshold. The consumption of all investigated alcoholic beverages, especially of white wine, triggered increased acidic GER, both in healthy participants and patients with reflux disease. In contrast, no relevant DGER was found after intake of alcoholic beverages.

CONCLUSIONS & INFERENCES

Fiber-optic bilirubin monitoring can be used for DGER monitoring in combination with alcoholic beverages, except with red wine. Low-proof alcoholic beverages are a strong trigger of GER, but not of DGER, both in healthy subjects and patients with reflux disease.

The expression of 8-hydroxydeoxyguanosine in oesophageal tissues and tumours

PURPOSE

The most common marker of oxidative DNA damage is 8-hydroxydeoxyguanosine (8-OHdG), which is linked with several malignancies. In the present study we investigated whether DNA damage linked to oxidative stress (as 8-OHdG) is present in Barrett's mucosa with or without associated adenocarcinoma or high-grade dysplasia and in normal controls' squamous mucosa.

EXPERIMENTAL DESIGN

We measured 8-OHdG in 51 patients (13 Barrett's metaplasia, six Barrett's oesophagus with high-grade dysplasia, 18 adenocarcinoma of the distal oesophagus/oesophagogastric junction and 14 normal controls). The amount of DNA damage was determined by high-performance liquid chromatography in oesophagus samples obtained either from endoscopy or as samples from surgery. The median 8-OHdG concentration was expressed as the ratio of 8-OHdG per 10(5) deoxyguanosine.

RESULTS

Analysis revealed that 8-OHdG was present in both Barrett's metaplasia with and without dysplasia as well as in adenocarcinoma of the oesophagus/oesophagogastric junction. Although the study group was small the amount of 8-OHdG was significantly increased in the distal oesophagus both in Barrett's epithelium 1.26 (0.08-29.47) and in high-grade dysplasia 1.35 (1.04-1.65) as well as in adenocarcinoma of oesophagus/oesophagogastric junction 1.08 (0.59-1.94) compared to controls 0.06 (0-4.08) (p=0.002, p=0.012, p=0.001, respectively). Barrett's patients had no significant difference in 8-OHdG levels between their distal and proximal oesophageal samples.

CONCLUSIONS

Our results show the presence of oxidative DNA damage in the distal oesophagus of patients with Barrett's oesophagus and adenocarcinoma of the oesophagus/oesophagogastric junction. This may have a connection to carcinogenesis in Barrett's oesophagus.