Helicobacter pylori and the molecular pathogenesis of intestinal-type gastric carcinoma

The status quo of short videos as a health information source of Helicobacter pylori: a cross-sectional study

Background

Health education about Helicobacter pylori (H. pylori) is one of the most effective methods to prevent H. pylori infection and standardize H. pylori eradication treatment. Short videos enable people to absorb and remember information more easily and are an important source of health education. This study aimed to assess the information quality of H. pylori-related videos on Chinese short video-sharing platforms.

Methods

A total of 242 H. pylori-related videos from three Chinese short video-sharing platforms with the most users, TikTok, Bilibili, and Kwai, were retrieved. The Global Quality Score (GQS) and the modified DISCERN tool were used to assess the quality and content of videos, respectively. Additionally, comparative analyzes of videos based on different sources and common H. pylori issues were also conducted.

Results

The median GQS score and DISCERN score was 2 for H. pylori-related videos analyzed in this study. Non-gastroenterologists posted the most H. pylori-related videos (136/242, 56.2%). Videos from gastroenterologists (51/242, 21.0%) had the highest GQS and DISCERN scores, with a median of 3. Few videos had content on family-based H. pylori infection control and management (5.8%), whether all H. pylori-positive patients need to undergo eradication treatment (27.7%), and the adverse effects of H. pylori eradication therapy (16.1%).

Conclusion

Generally, the content and quality of the information in H. pylori-related videos were unsatisfactory, and the quality of the video correlated with the source of the video. Videos from gastroenterologists provided more correct guidance with higher-quality information on the prevention and treatment of H. pylori infection.

Biomaterials for Helicobacter pylori therapy: therapeutic potential and future perspectives

Helicobacter pylori (H. pylori) is the main cause of gastric adenocarcinoma. However, the traditional antibiotic treatment of H. pylori is limited due to increased antibiotic resistance and low efficacy; low drug delivery efficiency and difficulties in eradicating H. pylori that is present intracellularly or in biofilms cause further setbacks. Biomaterials that can protect drugs against stomach acid, target lesions, control drug release, destroy biofilms, and exhibit unique antibacterial mechanisms and excellent biocompatibility have emerged as attractive tools for H. pylori eradication, particularly for drug-resistant strains. Herein, we review the virulence mechanisms, current drug treatments, and antibiotic resistance of H. pylori strains. Furthermore, recent advances in the development of biomaterials, including nanoparticles (such as lipid-based nanoparticles, polymeric nanoparticles, and inorganic nanoparticles), microspheres, and hydrogels, for effective and precise therapy of H. pylori and different types of therapeutic mechanisms, as well as future perspectives, have also been summarized.

Diagnostic laparoscopy is underutilized in the staging of gastric adenocarcinoma regardless of hospital type: An US safety net collaborative analysis

BACKGROUND

Diagnostic laparoscopy (DL) is a key component of staging for locally advanced gastric adenocarcinoma (GA). We hypothesized that utilization of DL varied between safety net (SNH) and affiliated tertiary referral centers (TRCs).

METHODS

Patients diagnosed with primary GA eligible for DL were identified from the US Safety Net Collaborative database (2012-2014). Clinicopathologic factors were analyzed for association with use of DL and findings on DL. Overall survival (OS) was analyzed by Kaplan-Meier method.

RESULTS

Among 233 eligible patients, 69 (30%) received DL, of which 24 (35%) were positive for metastatic disease. Forty percent of eligible SNH patients underwent DL compared to 21.5% at TRCs. Lack of insurance was significantly associated with decreased use of DL (OR 0.48, p < 0.01), while African American (OR 6.87, p = 0.02) and Asian race (OR 3.12, p ≤ 0.01), signet ring cells on biopsy (OR 3.14, p < 0.01), and distal tumors (OR 1.62, p < 0.01) were associated with increased use. Median OS of patients with a negative DL was better than those without DL or a positive DL (not reached vs. 32 vs. 12 months, p < 0.005, Figure 1).

CONCLUSIONS

Results from DL are a strong predictor of OS in GA; however, the procedure is underutilized. Patients from racial minority groups were more likely to undergo DL, which likely accounts for higher DL rates among SNH patients.

Role of Gastric Microorganisms Other than Helicobacter pylori in the Development and Treatment of Gastric Diseases

The microenvironment in the stomach is different from other digestive tracts, mainly because of the secretion of gastric acid and digestive enzymes, bile reflux, special mucus barrier, gastric peristalsis, and so on, which all contribute to the formation of antibacterial environment. Microecological disorders can lead to gastric immune disorders or lead to the decrease of dominant bacteria and the increase of the abundance and virulence of pathogenic microorganisms and then promote the occurrence of diseases. The body performs its immune function through innate and adaptive immunity and maintains microbial balance through the mechanism of immune homeostasis. Microecological imbalance can lead to the invasion of pathogenic microorganisms and damage mucosal barrier and immune system. The coexistence of gastric microorganisms (including viruses and fungi) may play a synergistic or antagonistic role in the pathogenesis of gastric diseases. Probiotics have the ability to compete with intestinal pathogens, increase the secretion of immunoglobulin A (IgA), stimulate the production of mucin, bacteriocin, and lactic acid, regulate the expression and secretion of cytokines, and regulate the growth of microbiota, which all have beneficial effects on the host microbial environment. At present, most studies focused on Helicobacter pylori, ignoring other stomach microbes and the overall stomach microecology. So, in this article, we reviewed advances in human gastric microecology, the relationship between gastric microecology and immunity or gastric diseases, and the treatment of probiotics in gastric diseases, in order to explore new area for further study of gastric microorganisms and treatment of gastric diseases.

Identifying the pre-malignant stomach: from guidelines to practice

Gastric adenocarcinoma develops after stepwise progression from normal mucosa through to adenocarcinoma most commonly after being triggered by Helicobacter pylori (H. pylori) infection. As disease is often diagnosed late, the prognosis for gastric adenocarcinoma is poor. Identifying pre-malignant mucosal lesions such as atrophic gastritis, intestinal metaplasia and dysplasia is one strategy adopted by clinicians to reduce cancer related mortality. Surveillance of high-risk individuals and endoscopic resection of dysplastic lesions is recommended by international and UK guidelines. The early detection and endoscopic management reduce the need for invasive surgery. The advancement of image enhanced endoscopy technology, endoscopic training, risk stratification and histological assessment has proven pivotal to the management of pre-malignant lesions. In this review we outline the development of a high-risk stomach, endoscopic assessment and review practical guidelines on identifying pre-malignant gastric mucosa.

Mechanisms of JARID1B Up-Regulation and Its Role in Helicobacter pylori-Induced Gastric Carcinogenesis

Gastric cancer (GC) is the third leading cause of cancer-related death worldwide. Helicobacter pylori infection can induce GC through a serial cascade of events, with emerging evidence suggesting the important role of epigenetic alterations in the development and progression of the disease. Here, we report on mechanisms responsible for Jumonji AT-rich interactive domain1B (JARID1B) upregulation in GC and its role in the malignant transformation induced by H. pylori infection. We found that upregulation of JARID1B was associated with poorer prognosis, greater tumor purity, and less immune cell infiltration into the tumor. Mechanistically, we showed that the upregulation of JARID1B in human GC was attributed to JARID1B amplification and its induction by H. pylori infection. Furthermore, we identified miR-29c as a negative regulator of JARID1B in GC. H. pylori caused downregulation of miR-29c in human GC and thereby contributed to JARID1B upregulation through relieving posttranscriptional regulation. Functionally, we showed that knockdown of JARID1B reduced GC cell proliferation induced by H. pylori infection. Subsequently, cyclinD1 (CCND1), a key molecule in GC, was shown to be a target gene of JARID1B. In conclusion, these results suggest that JARID1B may be an oncogene upregulated in human GC and could represent a novel therapeutic target to prevent malignant transformation induced by H. pylori infection.

Chemoprevention Against Gastric Cancer

Gastric cancer is the fifth most common cause of cancer and the third leading cause of cancer-related deaths globally. The number of gastric cancer-related deaths is only projected to increase, attributable primarily to the expanding aging population. Prevention is a mainstay of gastric cancer control programs, particularly in the absence of accurate, noninvasive modalities for screening and early detection, and the absence of an infrastructure for this purpose in the majority of countries worldwide. Herein, we discuss the evidence for several chemopreventive agents, along with putative mechanisms. There remains a clear, unmet need for primary chemoprevention trials for gastric cancer.

Impact of the Gut Microbiota Balance on the Health-Disease Relationship: The Importance of Consuming Probiotics and Prebiotics

Gut microbiota is a group of microorganisms that are deposited throughout the entire gastrointestinal tract. Currently, thanks to genomic tools, studies of gut microbiota have pointed towards the understanding of the metabolism of important bacteria that are not cultivable and their relationship with human homeostasis. Alterations in the composition of gut microbiota could explain, at least in part, some epidemics, such as diabetes and obesity. Likewise, dysbiosis has been associated with gastrointestinal disorders, neurodegenerative diseases, and even cancer. That is why several studies have recently been focused on the direct relationship that these types of conditions have with the specific composition of gut microbiota, as in the case of the microbiota-intestine-brain axis. In the same way, the control of microbiota is related to the diet. Therefore, this review highlights the importance of gut microbiota, from its composition to its relationship with the human health-disease condition, as well as emphasizes the effect of probiotic and prebiotic consumption on the balance of its composition.

Pyroptosis: mechanisms and diseases

Currently, pyroptosis has received more and more attention because of its association with innate immunity and disease. The research scope of pyroptosis has expanded with the discovery of the gasdermin family. A great deal of evidence shows that pyroptosis can affect the development of tumors. The relationship between pyroptosis and tumors is diverse in different tissues and genetic backgrounds. In this review, we provide basic knowledge of pyroptosis, explain the relationship between pyroptosis and tumors, and focus on the significance of pyroptosis in tumor treatment. In addition, we further summarize the possibility of pyroptosis as a potential tumor treatment strategy and describe the side effects of radiotherapy and chemotherapy caused by pyroptosis. In brief, pyroptosis is a double-edged sword for tumors. The rational use of this dual effect will help us further explore the formation and development of tumors, and provide ideas for patients to develop new drugs based on pyroptosis.

H. pylori infection alters repair of DNA double-strand breaks via SNHG17

Chronic infections can lead to carcinogenesis through inflammation-related mechanisms. Chronic infection of the human gastric mucosa with Helicobacter pylori is a well-known risk factor for gastric cancer. However, the mechanisms underlying H. pylori-induced gastric carcinogenesis are incompletely defined. We aimed to screen and clarify the functions of long noncoding RNAs (lncRNAs) that are differentially expressed in H. pylori-related gastric cancer. We found that lncRNA SNHG17 was upregulated by H. pylori infection and markedly increased the levels of double-strand breaks (DSBs). SNHG17 overexpression correlated with poor overall survival in patients with gastric cancer. The recruitment of NONO by overabundant nuclear SNHG17, along with the role of cytoplasmic SNHG17 as a decoy for miR-3909, which regulates Rad51 expression, shifted the DSB repair balance from homologous recombination toward nonhomologous end joining. Notably, during chronic H. pylori infection, SNHG17 knockdown inhibited chromosomal aberrations. Our findings suggest that spatially independent deregulation of the SNHG17/NONO and SNHG17/miR-3909/RING1/Rad51 pathways upon H. pylori infection promotes tumorigenesis in gastric cancer by altering the DNA repair system, which is critical for the maintenance of genomic stability. Upregulation of SNHG17 by H. pylori infection might be an undefined link between cancer and inflammation.

Microbiome and Gastric Cancer

The late 1800s Louis Pasteur and Robert Koch introduced and popularized the germ theory of disease. At that time, gastric cancer was the most common cause of cancer deaths in most countries making the stomach an early site of microbial research with a focus on gastric luminal and mucosal bacteria and the role of Boas-Oppler bacillus (Lactobacillus) in the diagnosis of gastric cancer. In the 1970s, the research focus evolved to studies of the gastric microbiome in the production of nitrosamines and included development of the Correa cascade. Interest in nitrosamine production peaked in the late 1980s and was replaced by studies of the newly described Helicobacter pylori and studies of its role in gastritis, gastric atrophy, and gastric cancer. The last decade has witnessed a rebirth in interest in the gastric microbiota as part of worldwide interest in the human microbiome. Although fungi were prominent in the studies of gastric microbiology in the nineteenth century, their potential role in disease pathogenesis has yet to be addressed using modern techniques. Overall, current studies of the gastric bacterial microbiome do not provide convincing evidence to expand the role of the gastric microbiome in cancer pathogenesis beyond what is directly attributable to the oncogenic potential of H. pylori and its role in persisting acute-on-chronic inflammation.

Gastric Damage and Cancer-Associated Biomarkers in Helicobacter pylori-Infected Children

Helicobacter pylori (H. pylori) is well-known to be involved in gastric carcinogenesis, associated with deregulation of cell proliferation and epigenetic changes in cancer-related genes. H. pylori infection is largely acquired during childhood, persisting long-term in about half of infected individuals, a subset of whom will go on to develop peptic ulcer disease and eventually gastric cancer, however, the sequence of events leading to disease is not completely understood. Knowledge on carcinogenesis and gastric damage-related biomarkers is abundant in adult populations, but scarce in children. We performed an extensive literature review focusing on gastric cancer related biomarkers identified in adult populations, which have been detected in children infected with H. pylori. Biomarkers were related to expression levels (RNA or protein) and/or methylation levels (DNA) in gastric tissue or blood of infected children as compared to non-infected controls. In this review, we identified 37 biomarkers of which 24 are over expressed, three are under expressed, and ten genes are significantly hypermethylated in H. pylori-infected children compared to healthy controls in at least 1 study. Only four of these biomarkers (pepsinogen I, pepsinogen II, gastrin, and SLC5A8) have been studied in asymptomatically infected children. Importantly, 13 of these biomarkers (β-catenin, C-MYC, GATA-4, DAPK1, CXCL13, DC-SIGN, TIMP3, EGFR, GRIN2B, PIM2, SLC5A8, CDH1, and VCAM-1.) are consistently deregulated in infected children and in adults with gastric cancer. Future studies should be designed to determine the clinical significance of these changes in infection-associated biomarkers in children and their persistence over time. The effect of eradication therapy over these biomarkers in children if proven significant, could lead to modifications in treatment guidelines for younger populations, and eventually promote the development of preventive strategies, such as vaccination, in the near future.

Investigation of DNA Double-Strand Breaks Induced in Host Cells Following Infection with Genotoxic Bacteria

Carcinogenesis is caused by genome instability, one of the major causes of which is double-strand DNA breaks (DSBs). Interestingly, infection by particular species of bacteria can induce DSBs in host cells. For example, several reports suggest an association between periodontal disease and oral cancer. Aggregatibacter actinomycetemcomitans, a common periodontal pathogen, causes DSBs in the host cell. Pulsed-field gel electrophoresis (PFGE) is often used to identify DSBs in host cells. However, as established during investigation of A. actinomycetemcomitans infection, it is often difficult to determine whether broken DNA fragments are indeed from human chromosomes or whether they are bacterial in origin using PFGE-based methods. Because the method involves the coculture of human cells with bacteria, both bacterial and human DNA fragments may be present in the broken DNA fraction. To address this problem, we have developed a method to detect only human chromosomal DNA upon PFGE analysis. Human chromosomes were prelabeled with halogenated deoxyuridine (e.g., BrdU and IdU) before being fractionated by PFGE and visualized by immunoblotting. As proof of concept, we successfully used this method to investigate the mechanism of DSB formation in host chromosomes following infection with genotoxic bacterial species.

Inhibition of polarity-regulating kinase PAR1b contributes to Helicobacter pylori inflicted DNA Double Strand Breaks in gastric cells

The serine/threonine kinase Par1 is a core component of the machinery that sets up polarity in the embryo and regulates cell fate decisions but its role in the homeostasis of adult tissues is poorly understood. Inhibition of Par1 by the bacterium Helicobacter pylori (H. pylori) represents the only established pathology that affects Par1 function in an adult epithelium. Thus, during chronic H. pylori infection of the gastric mucosa Par1 is one of the targets of the non-obligate H.pylori cytotoxic protein and oncogene CagA, which stimulates inflammation and triggers morphological changes, both believed to contribute to the gastric cancer risk imposed by H. pylori infection. Based on Par1's role in cell polarity, it has been speculated that Par1 inhibition affects epithelial polarity. Here we report the unexpected finding that CagA-mediated Par1-inhibition promotes the generation of DNA Double Strand Breaks in primary gastric epithelial cells, which likely contributes to the reported accumulation of mutations in chronically infected mucosal cells. Abbreviations: AGS: human gastric adenocarcinoma cell line; CM: CagA Multimerization (and Par1 binding) domain; H. pylori: Helicobacter pylori; DSB: Double Strand Break; HGECs: human (primary) gastric epithelial cells; IB: immunoblot; IF: immunofluorescence; MOI: Multiplicity of Infection; ROS: reactive oxygen species; Par1: Partitioning Defective 1 kinase; WT: wild type.

Guilt by association: intestinal metaplasia does not progress to gastric cancer

PURPOSE OF REVIEW

This review integrates the new thinking about relationships between gastric cancer and intestinal metaplasia/pseudopyloric metaplasia (SPEM). We address whether recent studies have closed or widened the knowledge gap regarding gastric cancer pathogenesis in mice or humans.

RECENT FINDINGS

Recent studies in mouse models have provided a variety of new insights into the cellular origin and progression of events resulting in gastric cancer. Many suggest a direct transformation from intestinal metaplasia/pseudopyloric metaplasia/SPEM to gastric cancer. However, results from different investigator and models are conflicting and often describe events not present in studies in humans.

SUMMARY

Both Helicobacter pylori-associated and autoimmune gastritis may produce gastric atrophy with extensive intestinal metaplasia and an abnormal gastric microbiome. However, only H. pylori gastritis carries a risk for adenocarcinoma. The differences reported with mouse models can best be explained as the results of different models of regeneration and repair rather than as models of gastric cancer. Overall, the data remains consistent with the original hypothesis that gastric cancer results from increased genetic instability of gastric stem cells rather than a direct transition from metaplasia to cancer. Intestinal metaplasia, pseudopyloric metaplasia, and SPEM have all been falsely accused based on guilt by association.

The evolving role of endoscopy in the diagnosis of premalignant gastric lesions

Gastric adenocarcinoma is a disease that is often detected late, at a stage when curative treatment is unachievable. This must be addressed through changes in our approach to the identification of patients at increased risk by improving the detection and risk assessment of premalignant changes in the stomach, including chronic atrophic gastritis and intestinal metaplasia. Current guidelines recommend utilising random biopsies in a pathology-led approach in order to stage the extent and severity of gastritis and intestinal metaplasia. This random method is poorly reproducible and prone to sampling error and fails to acknowledge recent advances in our understanding of the progression to gastric cancer as a non-linear, branching evolutionary model. Data suggest that recent advances in endoscopic imaging modalities, such as narrow band imaging, can achieve a high degree of accuracy in the stomach for the diagnosis of these premalignant changes. In this review, we outline recent data to support a paradigm shift towards an endoscopy-led approach to diagnosis and staging of premalignant changes in the stomach. High-quality endoscopic interrogation of the chronically inflamed stomach mucosa, supported by targeted biopsies, will lead to more accurate risk assessment, with reduced rates of under or missed diagnoses.

Risk of gastric cancer development after eradication of Helicobacter pylori

Helicobacter pylori (H. pylori) infection is the most important risk factor for gastric cancer (GC) development through the Correa’s gastric carcinogenesis cascade. However, H. pylori eradication alone does not eliminate GC, as pre-neoplastic lesions (atrophic gastritis, intestinal metaplasia and dysplasia) may have already developed in some patients. It is therefore necessary to identify patients at high-risk for gastric cancer after H. pylori eradication to streamline the management plan. If the patients have not undergone endoscopy with histologic assessment, the identification of certain clinical risk factors and non-invasive testing (serum pepsinogen) can predict the risk of atrophic gastritis. For those with suspected atrophic gastritis, further risk stratification by endoscopy with histologic assessment according to validated histologic staging systems would be advisable. Patients with higher stages may require long-term endoscopic surveillance. Apart from secondary prevention to reduce deaths by diagnosing GC at an early stage, identifying medications that could potentially modify the GC risk would be desirable. The potential roles of a number of medications have been suggested by various studies, including proton pump inhibitors (PPIs), aspirin, statins and metformin. However, there are currently no randomized clinical trials to address the impact of these medications on GC risk after H. pylori eradication. In addition, most of these studies failed to adjust for the effect of concurrent medications on GC risk. Recently, large population-based retrospective cohort studies have shown that PPIs were associated with an increased GC risk after H. pylori eradication, while aspirin was associated with a lower risk. The roles of other agents in reducing GC risk after H. pylori eradication remain to be determined.

Quantitative real-time PCR-based assessment of tile drainage management influences on bacterial pathogens in tile drainage and groundwater

This study compared the impact of controlled tile drainage (CD) and freely draining (FD) systems on the prevalence and quantitative real-time PCR-based enumeration of four major pathogens including Arcobacter butzleri, Campylobacter jejuni, Campylobacter coli, and Helicobacter pylori in tile- and groundwater following a fall liquid swine manure (LSM) application on clay loam field plots. Although the prevalence of all target pathogens were detected in CD and FD systems, the loads of A. butzleri, C. jejuni, and C. coli were significantly lower in CD tile-water (p<0.05), in relation to FD tile-water. However, concentrations of A. butzleri were significantly greater in CD than FD tile-water (p<0.05). In shallow groundwater (1.2m depth), concentrations of A. butzleri, C. coli, and H. pylori showed no significant difference between CD and FD plots, while C. jejuni concentrations were significantly higher in FD plots (p<0.05). No impact of CD on the H. pylori was observed since quantitative detection in tile- and groundwater was scarce. Although speculative, H. pylori occurrence may have been related to the application of municipal biosolids four years prior to the LSM experiment. Overall, CD can be used to help minimize off-field export of pathogens into surface waters following manure applications to land, thereby reducing waterborne pathogen exposure risks to humans.

Fas-associated factor 1 inhibits tumor growth by suppressing Helicobacter pylori-induced activation of NF-κB signaling in human gastric carcinoma

Loss of Fas-associated factor 1 (FAF1) may act as a pro-survival signal in diseased cells, but whether this is true in gastric carcinoma remains unclear. Here we report that FAF1 was expressed at low levels in gastric carcinoma tissues and cell lines, and its expression correlated with larger tumors, higher histology grade, higher TNM stage, tumor infiltration, and lymph node metastasis. Univariate analysis and survival curve analysis identified low FAF1 expression as a predictor of poor prognosis. FAF1 overexpression in HGC-27 gastric cancer cells induced cell apoptosis and inhibited cell proliferation and growth. It also reduced colony formation in vitro and tumor growth in mice. We found that Helicobacter pylori, a risk factor for gastric cancer, down-regulated FAF1 expression via NF-κB signaling. Knock-down of IKKβ or p65 expression in gastric cancer cells reversed H. pylori-induced down-regulation of FAF1 expression and partially blocked H. pylori-induced secretion of inflammatory cytokines TNF-α and IL-8. Our results suggest that loss of FAF1 contributes to human gastric carcinogenesis by allowing H. pylori to activate NF-κB signaling.

Aggregatibacter actinomycetemcomitans infection causes DNA double-strand breaks in host cells

Periodontal disease, an inflammatory disease, is caused by infection with periodontal pathogens. Long-term periodontal disease increases the risk of oral carcinogenesis. Similar to other peptic cancers, oral carcinogenesis also requires multiple genome instabilities; however, the risk factors related to the accumulation of genome instabilities are poorly understood. Here, we suggested that specific periodontal pathogens may increase the risk of genome instability. Accordingly, we screened several periodontal pathogens based on the ability to induce DNA double-strand breaks (DSBs) in host cells. We found that Aggregatibacter actinomycetemcomitans Y4 infection induced DSB formation in host cells. To assess whether DSB formation induced by infection with A. actinomycetemcomitans occurred through apoptotic chromosome fragmentation, cells were treated with a caspase inhibitor, Z-VAD-FMK. DSB accumulation induced by infection with A. actinomycetemcomitans was observed, even in the presence of Z-VAD-FMK, suggesting that this breakage occurred independently of apoptosis. These results suggested that some periodontal pathogens can increase the risk of genome instabilities in host cells and subsequently increase the risk of carcinogenesis.

Gastric Cancer as Preventable Disease

Gastric cancer, 1 of the 5 most common causes of cancer death, is associated with a 5-year overall survival rate less than 30%. A minority of cancers occurs as part of syndromic diseases; more than 90% of adenocarcinomas are considered as the ultimate consequence of a longstanding mucosal inflammation. Helicobacter pylori infection is the leading etiology of non-self-limiting gastritis, which may result in atrophy of the gastric mucosa and impaired acid secretion. Gastric atrophy establishes a field of cancerization prone to further molecular and phenotypic changes, possibly resulting in cancer growth. This well-understood natural history provides the clinicopathologic rationale for primary and secondary cancer prevention strategies. A large body of evidence demonstrates that combined primary (H pylori eradication) and secondary (mainly endoscopy) prevention efforts may prevent or limit the progression of gastric oncogenesis. This approach, which is tailored to different country-specific gastric cancer incidence, socioeconomic, and cultural factors, requires that the complementary competences of gastroenterologists, oncologists, and pathologists be amalgamated into a common strategy of health policy.

Helicobacter pylori as an oncogenic pathogen, revisited

Gastric cancer is an inflammation-associated malignancy aetiologically related to infection with the bacterium, Helicobacter pylori, which is considered a necessary but insufficient cause. Unless treated, H. pylori causes life-long acute and chronic gastric inflammation resulting in progressive gastric mucosal damage that may result in gastric cancer. The rate of progression from superficial gastritis, to an atrophic metaplastic mucosa, and ultimately to cancer relates to the virulence of the infecting H. pylori as well as host and environmental factors. H. pylori virulence is a reflection of its propensity to cause severe gastric inflammation. Both mucosal inflammation and H. pylori can cause host genomic instability, including dysregulation of DNA mismatch repair, stimulation of expression of activation-induced cytidine deaminase, abnormal DNA methylation and dysregulation of  micro RNAs, which may result in an accumulation of mutations and loss of normal regulation of cell growth. The difference in cancer risk between the most and least virulent H. pylori strain is only approximately 2-fold. Overall, none of the putative virulence factors identified to date have proved to be disease-specific. The presence, severity, extent and duration of inflammation appear to be the most important factors and current evidence suggests that any host, environmental or bacterial factor that reliably enhances the inflammatory response to the H. pylori infection increases the risk of gastric cancer.

Helicobacter pylori Infection Is Associated with Decreased Expression of SLC5A8, a Cancer Suppressor Gene, in Young Children

Background:Helicobacter pylori infects half of the world's population and causes gastric cancer in a subset of infected adults. Previous blood microarray findings showed that apparently healthy children, persistently infected with H. pylori have differential gene expression compared to age-matched, non-infected children. SLC5A8, a cancer suppressor gene with decreased expression among infected children, was chosen for further study based on bioinformatics analysis. Methods: A pilot study was conducted using specific qRT-PCR amplification of SLC5A8 in blood samples from H. pylori infected and non-infected children, followed by a larger, blinded, case-control study. We then analyzed gastric tissue from H. pylori infected and non-infected children undergoing endoscopy for clinical purposes. Results: Demographics, clinical findings, and family history were similar between groups. SLC5A8 expression was decreased in infected vs. non-infected children in blood, 0.12 (IQR: 0-0.89) vs. 1.86 (IQR: 0-8.94, P = 0.002), and in gastric tissue, 0.08 (IQR: 0.04-0.15) vs. 1.88 (IQR: 0.55-2.56; P = 0.001). Children who were both stool positive and seropositive for H. pylori had the lowest SLC5A8 expression levels. Conclusions:H. pylori infection is associated with suppression of SCL5A8, a cancer suppressor gene, in both blood and tissue samples from young children. Key Points: Young children, persistently infected with Helicobacter pylori show decreased expression of SLC5A8 mRNA in both blood and tissue samples as compared to non-infected children.

Oncogenic viruses: Lessons learned using next-generation sequencing technologies

Fifteen percent of cancers are driven by oncogenic human viruses. Four of those viruses, hepatitis B virus, human papillomavirus, Merkel cell polyomavirus, and human T-cell lymphotropic virus, integrate the host genome. Viral oncogenesis is the result of epigenetic and genetic alterations that happen during viral integration. So far, little data have been available regarding integration mechanisms and modifications in the host genome. However, the emergence of high-throughput sequencing and bioinformatic tools enables researchers to establish the landscape of genomic alterations and predict the events that follow viral integration. Cooperative working groups are currently investigating these factors in large data sets. Herein, we provide novel insights into the initiating events of cancer onset during infection with integrative viruses. Although much remains to be discovered, many improvements are expected from the clinical point of view, from better prognosis classifications to better therapeutic strategies.

Prostate stem cell antigen gene TT genotype and development of intestinal metaplasia in Helicobacter pylori infection

OBJECTIVES

Gastric cancer is etiologically related to interactions between Helicobacter pylori (H. pylori) infection, environmental and host factors. Gastric carcinoma is associated with a cascade of increasing atrophic gastric mucosal damage. Prostate stem cell antigen (PSCA) polymorphisms have been associated with an increased risk of gastric cancer. We aimed to examine the interaction between PSCA polymorphisms and H. pylori in the progression of H. pylori-related gastritis.

METHODS

The genotypes (TT, TC and CC) of PSCA single nucleotide polymorphism rs2294008 among H. pylori infected and uninfected Bhutanese were compared with the severity of H. pylori-related gastritis [neutrophils, monocytes, atrophy scores, H. pylori density, and the presence and extent of intestinal metaplasia (IM)] using the updated Sydney system.

RESULTS

Biopsies from 339 participants were included. The proportion of biopsies with IM was significantly (P < 0.05) greater in those with the TT genotype than in either those with the CT or CC genotype. Although no significant differences were found in inflammation or H. pylori density scores, the scores for IM at both gastric corpus and antrum among participants infected by H. pylori with the TT genotype was significantly (P < 0.05) greater than in the C allele carriers.

CONCLUSION

PSCA TT genotype is associated with a more than a threefold increase in the prevalence and the extent of gastric mucosal IM compared to C allele carriers among H. pylori-infected Bhutanese.

Effect of Helicobacter pylori Eradication on Long-Term Survival after Distal Gastrectomy for Gastric Cancer

Purpose

Negative Helicobacter pylori status has been identified as a poor prognostic factor for survival in gastric cancer (GC) patients who underwent surgery. The aim of this study was to examine the effect of H. pylori eradication on long-term outcomes after distal gastrectomy for GC.

Materials and Methods

We analyzed the survival of 169 distal GC patients enrolled in a prospective randomized trial evaluating histologic changes of gastric mucosa after H. pylori eradication in the remnant stomach. The outcomes measured were overall survival (OS) and GC recurrence rates.

Results

The median follow-up duration was 9.4 years. In the modified intention-to-treat analysis including patients who underwent H. pylori treatment (n=87) or placebo (n=82), 5-year OS rates were 98.9% in the treatment group and 91.5% in the placebo group, and Kaplan-Meier analysis showed no significant difference in OS (p=0.957) between groups. In multivariate analysis, no difference in overall mortality was observed between groups (adjusted hazard ratio [aHR] for H. pylori treatment, 0.75; p=0.495) or H. pylori-eradicated status (aHR for positive H. pylori status, 1.16; p=0.715), while old age, male sex, and advanced stage ≥ IIIa were independent risk factors. Six patients in the treatment group (6.9%) and seven patients in the placebo group (8.5%) had GC recurrences, and GC recurrence rates were not different according to H. pylori treatment (5-year GC recurrence rates, 4.6% in the treatment group vs. 8.5% in the placebo group; p=0.652).

Conclusion

H. pylori eradication for GC patients who underwent distal gastrectomy did not compromise long-term survival after surgery.

Helicobacter pylori update: gastric cancer, reliable therapy, and possible benefits

Helicobacter pylori infection contributes to the development of diverse gastric and extragastric diseases. The infection is necessary but not sufficient for the development of gastric adenocarcinoma. Its eradication would eliminate a major worldwide cause of cancer death, therefore there is much interest in identifying how, if, and when this can be accomplished. There are several mechanisms by which H pylori contributes to the development of gastric cancer. Gastric adenocarcinoma is one of many cancers associated with inflammation, which is induced by H pylori infection, yet the bacteria also cause genetic and epigenetic changes that lead to genetic instability in gastric epithelial cells. H pylori eradication reduces both. However, many factors must be considered in determining whether treating this bacterial infection will prevent cancer or only reduce its risk-these must be considered in designing reliable and effective eradication therapies. Furthermore, H pylori infection has been proposed to provide some benefits, such as reducing the risks of obesity or childhood asthma. When tested, these hypotheses have not been confirmed and are therefore most likely false.

Roadmap for elimination of gastric cancer in Korea

Most gastric cancers are caused by infection with the common human bacterial pathogen, Helicobacter pylori. It is now accepted that gastric cancer can be prevented and virtually eliminated by H. pylori eradication and this knowledge was responsible for country-wide H. pylori eradication combined with secondary cancer prevention for those with residual risk that was introduced in Japan in 2013. Korea is a high H. pylori prevalence and high gastric cancer incidence country and a good candidate for a gastric cancer elimination program. The presence of an H. pylori infection is now considered as an indication for treatment of the infection. However, antimicrobial drug resistance is common among H. pylori in Korea making effective therapy problematic. Country-wide studies of the local and regional antimicrobial resistance patterns are needed to choose the most appropriate therapies. H. pylori and gastric cancer eradication can be both efficient and cost effective making it possible and practical to make Korea H. pylori and gastric cancer free. There is no reason to delay.

Individual risk stratification of gastric cancer: evolving concepts and their impact on clinical practice

Gastric cancer (GC) is the third leading cause of cancer-related death worldwide and it mostly develops in long-standing inflammatory conditions, and Helicobacter pylori-gastritis, in particular. Despite the increasing understanding of both the phenotypic alterations and the molecular mechanisms occurring during GC multi-step carcinogenesis, no reliable biomarker is available to be reliably implemented into GC secondary prevention strategies. Multidisciplinary diagnostic approaches integrating endoscopy, serology, histology and molecular profiling currently appears as the most appropriate approach for patients' stratification into different GC risk classes.

An Update on Helicobacter pylori as the Cause of Gastric Cancer

BACKGROUND

Gastric cancer is the second most common cause of cancer deaths worldwide. The vast majority of gastric cancers are inflammation-related cancers caused by infection with Helicobacter pylori. H. pylori-induced oxidative stress damages DNA, resulting in genetic instability. In addition, H. pylori itself can cause DNA damage and epigenetic changes that trigger genetic instability and neoplastic transformation.

SUMMARY

H. pylori strain-specific components act in combination with host factors and environmental and dietary factors to greatly enhance the inflammatory response and thus the cancer risk. Variations in several key factors, such as the cag pathogenicity island and the VacA protein, can trigger a greater inflammatory response in host cells. Genetic polymorphisms in the host such as in the IL-1β gene, and chromosomes 9p21.3 and 10q23 also play a contributing role. Finally, diet is a major external factor that modulates the risk of gastric cancer.

KEY MESSAGE

The majority of gastric cancers are inflammation-related cancers caused by infection with H. pylori. Eradication of H. pylori is important for the prevention and treatment of gastric cancer.

PRACTICAL IMPLICATIONS

H. pylori eradication results in healing of gastritis and prevention of further H. pylori-induced genetic damage. Eradication of H. pylori prior to development of atrophic gastritis can prevent the development of gastric cancer. Japan has undertaken a nationwide program to identify and eliminate H. pylori, along with surveillance for those who underwent H. pylori eradication too late to eliminate cancer risk. Population-wide eradication of H. pylori will result in gastric cancer becoming a vanishingly rare disease.