Causal role of Helicobacter pylori infection in gastric cancer: An Asian enigma

DNA methylation drives a new path in gastric cancer early detection: Current impact and prospects

Gastric cancer (GC) is one of the most common and deadly cancers worldwide. Early detection offers the best chance for curative treatment and reducing its mortality. However, the optimal population-based early screening for GC remains unmet. Aberrant DNA methylation occurs in the early stage of GC, exhibiting cancer-specific genetic and epigenetic changes, and can be detected in the media such as blood, gastric juice, and feces, constituting a valuable biomarker for cancer early detection. Furthermore, DNA methylation is a stable epigenetic alteration, and many innovative methods have been developed to quantify it rapidly and accurately. Nonetheless, large-scale clinical validation of DNA methylation serving as tumor biomarkers is still lacking, precluding their implementation in clinical practice. In conclusion, after a critical analysis of the recent existing literature, we summarized the evolving roles of DNA methylation during GC occurrence, expounded the newly discovered noninvasive DNA methylation biomarkers for early detection of GC, and discussed its challenges and prospects in clinical applications.

Helicobacter pylori and Its Role in Gastric Cancer

Gastric cancer is a challenging public health concern worldwide and remains a leading cause of cancer-related mortality. The primary risk factor implicated in gastric cancer development is infection with Helicobacter pylori. H. pylori induces chronic inflammation affecting the gastric epithelium, which can lead to DNA damage and the promotion of precancerous lesions. Disease manifestations associated with H. pylori are attributed to virulence factors with multiple activities, and its capacity to subvert host immunity. One of the most significant H. pylori virulence determinants is the cagPAI gene cluster, which encodes a type IV secretion system and the CagA toxin. This secretion system allows H. pylori to inject the CagA oncoprotein into host cells, causing multiple cellular perturbations. Despite the high prevalence of H. pylori infection, only a small percentage of affected individuals develop significant clinical outcomes, while most remain asymptomatic. Therefore, understanding how H. pylori triggers carcinogenesis and its immune evasion mechanisms is critical in preventing gastric cancer and mitigating the burden of this life-threatening disease. This review aims to provide an overview of our current understanding of H. pylori infection, its association with gastric cancer and other gastric diseases, and how it subverts the host immune system to establish persistent infection.

Molecular mechanisms underlying the action of carcinogens in gastric cancer with a glimpse into targeted therapy

BACKGROUND

Gastric cancer imposes a substantial global health burden despite its overall incidence decrease. A broad spectrum of inherited, environmental and infectious factors contributes to the development of gastric cancer. A profound understanding of the molecular underpinnings of gastric cancer has lagged compared to several other tumors with similar incidence and morbidity rates, owing to our limited knowledge of the role of carcinogens in this malignancy. The International Agency for Research on Cancer (IARC) has classified gastric carcinogenic agents into four groups based on scientific evidence from human and experimental animal studies. This review aims to explore the potential comprehensive molecular and biological impacts of carcinogens on gastric cancer development and their interactions and interferences with various cellular signaling pathways.

CONCLUSIONS

In this review, we highlight recent clinical trial data reported in the literature dealing with different ways to target various carcinogens in gastric cancer. Moreover, we touch upon other multidisciplinary therapeutic approaches such as surgery, adjuvant and neoadjuvant chemotherapy. Rational clinical trials focusing on identifying suitable patient populations are imperative to the success of single-agent therapeutics. Novel insights regarding signaling pathways that regulate gastric cancer can potentially improve treatment responses to targeted therapy alone or in combination with other/conventional treatments. Preventive strategies such as control of H. pylori infection through eradication or immunization as well as dietary habit and lifestyle changes may reduce the incidence of this multifactorial disease, especially in high prevalence areas. Further in-depth understanding of the molecular mechanisms involved in the role of carcinogenic agents in gastric cancer development may offer valuable information and update state-of-the-art resources for physicians and researchers to explore novel ways to combat this disease, from bench to bedside. A schematic outlining of the interaction between gastric carcinogenic agents and intracellular pathways in gastric cancer H. pylori stimulates multiple intracellular pathways, including PI3K/AKT, NF-κB, Wnt, Shh, Ras/Raf, c-MET, and JAK/STAT, leading to epithelial cell proliferation and differentiation, apoptosis, survival, motility, and inflammatory cytokine release. EBV can stimulate intracellular pathways such as the PI3K/Akt, RAS/RAF, JAK/STAT, Notch, TGF-β, and NF-κB, leading to cell survival and motility, proliferation, invasion, metastasis, and the transcription of anti-apoptotic genes and pro-inflammatory cytokines. Nicotine and alcohol can lead to angiogenesis, metastasis, survival, proliferation, pro-inflammatory, migration, and chemotactic by stimulating various intracellular signaling pathways such as PI3K/AKT, NF-κB, Ras/Raf, ROS, and JAK/STAT. Processed meat contains numerous carcinogenic compounds that affect multiple intracellular pathways such as sGC/cGMP, p38 MAPK, ERK, and PI3K/AKT, leading to anti-apoptosis, angiogenesis, metastasis, inflammatory responses, proliferation, and invasion. Lead compounds may interact with multiple signaling pathways such as PI3K/AKT, NF-κB, Ras/Raf, DNA methylation-dependent, and epigenetic-dependent, leading to tumorigenesis, carcinogenesis, malignancy, angiogenesis, DNA hypermethylation, cell survival, and cell proliferation. Stimulating signaling pathways such as PI3K/Akt, RAS/RAF, JAK/STAT, WNT, TGF-β, EGF, FGFR2, and E-cadherin through UV ionizing radiation leads to cell survival, proliferation, and immortalization in gastric cancer. The consequence of PI3K/AKT, NF-κB, Ras/Raf, ROS, JAK/STAT, and WNT signaling stimulation by the carcinogenic component of Pickled vegetables and salted fish is the Warburg effect, tumorigenesis, angiogenesis, proliferation, inflammatory response, and migration.

The endemic Helicobacter pylori population in Southern Vietnam has both South East Asian and European origins

Background

The burden of Helicobacter pylori-induced gastric cancer varies based on predominant H. pylori population in various geographical regions. Vietnam is a high H. pylori burden country with the highest age-standardized incidence rate of gastric cancer (16.3 cases/100,000 for both sexes) in Southeast Asia, despite this data on the H. pylori population is scanty. We examined the global context of the endemic H. pylori population in Vietnam and present a contextual and comparative genomics analysis of 83 H. pylori isolates from patients in Vietnam.

Results

There are at least two major H. pylori populations are circulating in symptomatic Vietnamese patients. The majority of the isolates (~ 80%, 66/83) belong to the hspEastAsia and the remaining belong to hpEurope population (~ 20%, 17/83). In total, 66 isolates (66/83) were cagA positive, 64 were hspEastAsia isolates and two were hpEurope isolates. Examination of the second repeat region revealed that most of the cagA genes were ABD type (63/66; 61 were hspEastAsia isolates and two were hpEurope isolates). The remaining three isolates (all from hspEastAsia isolates) were ABC or ABCC types. We also detected that 4.5% (3/66) cagA gene from hspEastAsia isolates contained EPIYA-like sequences, ESIYA at EPIYA-B segments. Analysis of the vacA allelic type revealed 98.8% (82/83) and 41% (34/83) of the strains harboured the s1 and m1 allelic variant, respectively; 34/83 carried both s1m1 alleles. The most frequent genotypes among the cagA positive isolates were vacA s1m1/cagA + and vacA s1m2/cagA + , accounting for 51.5% (34/66) and 48.5% (32/66) of the isolates, respectively.

Conclusions

There are two predominant lineages of H. pylori circulating in Vietnam; most of the isolates belong to the hspEastAsia population. The hpEurope population is further divided into two smaller clusters.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13099-021-00452-2.

Helicobacter pylori in Human Stomach: The Inconsistencies in Clinical Outcomes and the Probable Causes

Pathogenic potentials of the gastric pathogen, Helicobacter pylori, have been proposed, evaluated, and confirmed by many laboratories for nearly 4 decades since its serendipitous discovery in 1983 by Barry James Marshall and John Robin Warren. Helicobacter pylori is the first bacterium to be categorized as a definite carcinogen by the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO). Half of the world’s population carries H. pylori, which may be responsible for severe gastric diseases like peptic ulcer and gastric cancer. These two gastric diseases take more than a million lives every year. However, the role of H. pylori as sole pathogen in gastric diseases is heavily debated and remained controversial. It is still not convincingly understood, why most (80–90%) H. pylori infected individuals remain asymptomatic, while some (10–20%) develop such severe gastric diseases. Moreover, several reports indicated that colonization of H. pylori has positive and negative associations with several other gastrointestinal (GI) and non-GI diseases. In this review, we have discussed the state of the art knowledge on “H. pylori factors” and several “other factors,” which have been claimed to have links with severe gastric and duodenal diseases. We conclude that H. pylori infection alone does not satisfy the “necessary and sufficient” condition for developing aggressive clinical outcomes. Rather, the cumulative effect of a number of factors like the virulence proteins of H. pylori, local geography and climate, genetic background and immunity of the host, gastric and intestinal microbiota, and dietary habit and history of medicine usage together determine whether the H. pylori infected person will remain asymptomatic or will develop one of the severe gastric diseases.

Helicobacter pylori-Induced Inflammation: Possible Factors Modulating the Risk of Gastric Cancer

Chronic inflammation and long-term tissue injury are related to many malignancies, including gastric cancer (GC). Helicobacter pylori (H. pylori), classified as a class I carcinogen, induces chronic superficial gastritis followed by gastric carcinogenesis. Despite a high prevalence of H. pylori infection, only about 1–3% of people infected with this bacterium develop GC worldwide. Furthermore, the development of chronic gastritis in some, but not all, H. pylori-infected subjects remains unexplained. These conflicting findings indicate that clinical outcomes of aggressive inflammation (atrophic gastritis) to gastric carcinogenesis are influenced by several other factors (in addition to H. pylori infection), such as gut microbiota, co-existence of intestinal helminths, dietary habits, and host genetic factors. This review has five goals: (1) to assess our current understanding of the process of H. pylori-triggered inflammation and gastric precursor lesions; (2) to present a hypothesis on risk modulation by the gut microbiota and infestation with intestinal helminths; (3) to identify the dietary behavior of the people at risk of GC; (4) to check the inflammation-related genetic polymorphisms and role of exosomes together with other factors as initiators of precancerous lesions and gastric carcinoma; and (5) finally, to conclude and suggest a new direction for future research.

Management of Helicobacter pylori infection: The Bhubaneswar Consensus Report of the Indian Society of Gastroenterology

The Indian Society of Gastroenterology (ISG) felt the need to organize a consensus on Helicobacter pylori (H. pylori) infection and to update the current management of H. pylori infection; hence, ISG constituted the ISG's Task Force on Helicobacter pylori. The Task Force on H. pylori undertook an exercise to produce consensus statements on H. pylori infection. Twenty-five experts from different parts of India, including gastroenterologists, pathologists, surgeons, epidemiologists, pediatricians, and microbiologists participated in the meeting. The participants were allocated to one of following sections for the meeting: Epidemiology of H. pylori infection in India and H. pylori associated conditions; diagnosis; treatment and retreatment; H. pylori and gastric cancer, and H. pylori prevention/public health. Each group reviewed all published literature on H. pylori infection with special reference to the Indian scenario and prepared appropriate statements on different aspects for voting and consensus development. This consensus, which was produced through a modified Delphi process including two rounds of face-to-face meetings, reflects our current understanding and recommendations for the diagnosis and management of H. pylori infection. These consensus should serve as a reference for not only guiding treatment of H. pylori infection but also to guide future research on the subject.

Helicobacter pylori healthy South Asians

We aimed to estimate the pooled prevalence of Helicobacter pylori among asymptomatic South Asians based on available literature and highlight the importance of screening asymptomatic individuals and implementing preventive strategies for eradicating H. pylori. Electronic databases such as PubMed and Embase, a regional database of WHO South Asian Region, and gray literature sites were searched for relevant studies from 1983 to 5 May 2020. In addition, references of the included studies were thoroughly searched. The random-effect model was used to calculate the pooled prevalence with a 95% confidence interval (CI) along with subgroup analysis. Analysis of 19 studies showed a pooled prevalence of 56.5%, ranging from 10.3 to 91.7%. In subgroup analysis by country, the highest prevalence rate was reported from Bangladesh (86.3%, 95% CI: 0.806-0.921), whereas the lowest prevalence was from Sri Lanka (10.3%, 95% CI: 0.072-0.135). No differences were found between males and females. Prevalence among children and adolescents was 65.3% (95% CI: 0.529-0.777), greater than adults, 56.9% (95% CI: 0.353-0.785). The prevalence rate showed a decreasing trend upon comparison of studies conducted before and after 2000. Our analysis reveals the high prevalence of H. pylori infection among asymptomatic healthy populations in South Asia, particularly in children and adolescents. Public health awareness and sanitation interventions, pure drinking water, and respective strategies on a policy level to eradicate H. pylori and additional extensive multicentric cohort studies are necessary.

Regional variations in Helicobacter pylori infection, gastric atrophy and gastric cancer risk: The ENIGMA study in Chile

BACKGROUND

Regional variations in gastric cancer incidence are not explained by prevalence of Helicobacter pylori, the main cause of the disease, with several areas presenting high H. pylori prevalence but low gastric cancer incidence. The IARC worldwide H. pylori prevalence surveys (ENIGMA) aim at systematically describing age and sex-specific prevalence of H. pylori infection around the world and generating hypotheses to explain regional variations in gastric cancer risk.

METHODS

We selected age- and sex-stratified population samples in two areas with different gastric cancer incidence and mortality in Chile: Antofagasta (lower rate) and Valdivia (higher rate). Participants were 1-69 years old and provided interviews and blood for anti-H. pylori antibodies (IgG, VacA, CagA, others) and atrophy biomarkers (pepsinogens).

RESULTS

H. pylori seroprevalence (Age-standardized to world population) and antibodies against CagA and VacA were similar in both sites. H. pylori seroprevalence was 20% among children <10 years old, 40% among 10-19 year olds, 60% in the 20-29 year olds and close to or above 80% in those 30+ years. The comparison of the prevalence of known and potential H. pylori cofactors in gastric carcinogenesis between the high and the low risk area showed that consumption of chili products was significantly higher in Valdivia and daily non-green vegetable consumption was more common in Antofagasta. Pepsinogen levels suggestive of gastric atrophy were significantly more common and occurred at earlier ages in Valdivia, the higher risk area. In a multivariate model combining both study sites, age, chili consumption and CagA were the main risk factors for gastric atrophy.

CONCLUSIONS

The prevalence of H. pylori infection and its virulence factors was similar in the high and the low risk area, but atrophy was more common and occurred at younger ages in the higher risk area. Dietary factors could partly explain higher rates of atrophy and gastric cancer in Valdivia.

IMPACT

The ENIGMA study in Chile contributes to better understanding regional variations in gastric cancer incidence and provides essential information for public health interventions.

Association of Helicobacter pylori vacA genotypes and peptic ulcer in Iranian population: a systematic review and meta-analysis

BACKGROUND

Helicobacter pylori is accounted as the most etiologic agent for digestive disorders, in particular, the most important of them i.e. peptic ulcer and gastric cancer. In the recent years, association of vacA genotypes and gastrointestinal disorders has attracted a lot of attention. In present study, we assessed the correlation between vacA genotypes (s1, s2, m1, m2, s1m1, s1m2, s2m1 and s2m2) and development to peptic ulcer in Iranian population.

METHODS

In our study, first, 24 original articles containing of information of 3328 patients were evaluated. Statistical analysis was done by Comprehensive Meta-Analysis version 2.0 software (Biostat, Englewood, NJ, USA). In this regards, we used from fixed-effects model for analysis of data with low heterogeneity, while for analysis of data with high heterogeneity (I2 statistic index > 25%, Cochrane Q statistic p value < 0.05), random-effects model was used.

RESULTS

Abundance of each of s1, s2, m1, m2, s1m1, s1m2, s2m1, and s2m2 was estimated 36.24, 28.32, 42.90 29.86, 27.88, 32.34, 15.70, and 25.94%, respectively. According to the results, the m1, s1, and s1m2 genotypes were among the most prevalent genotypes among the Iranian patients, whereas, s2m1 genotype had the lowest frequency.

CONCLUSIONS

Overall, 24 articles (total participants = 3328) were included in this comprehensive analysis. H. pylori infection rate were 90.26% in these cases, so that 33.65% of whom had peptic ulcer. Moreover, the abundance of each vacA genotypes including s1, s2, m1, m2, s1m1, s1m2, s2m1, and s2m2 was estimated as 36.24, 28.32, 42.90 29.86, 27.88, 32.34, 15.70, and 25.94% respectively. We demonstrated that there is a significant relationship between infection of stomach with m1, s1m1, and s2m1 genotypes and development to peptic ulcer disease.

Oral rinses in growth inhibition and treatment of Helicobacter pylori infection

BACKGROUND

Helicobacter pylori (H. pylori) is well-known for its role in chronic gastritis and gastric cancer. Eradication of these carcinogenic bacteria from the gut is one of the challenges for clinicians. The complexity of treatment mainly owes to antibiotic resistance and relapse due to an additional reservoir in the oral cavity. Our study emphases the isolation of H. pylori from distinct habitats of the gut microenvironment (gastric biopsy and gastric juice) and its subsequent characterization. We have also evaluated the effect of various oral rinses on isolated H. pylori from different anatomical locations of included subjects.

RESULTS

The possible strains isolated from two different habitats of the same subject shows a striking difference in their growth pattern. Promisingly, some of the included oral rinses are efficient in growth inhibition as per recommended 30 s treatment. The subsequent evaluation shows that oral rinse B (among A-E) is most effective and down-regulates the expression of one of the potent H. pylori gene, CagA, in the infected gastric adenocarcinoma (AGS) cells.

CONCLUSION

Our study, for the first time, revealed that H. pylori, isolated from the different habitat of the same subject, show a different growth pattern. The expression of H. pylori pathogenic gene (CagA) was down-regulated by the use of oral rinses. Hence, oral rinses will reduce the H. pylori in the oral cavity and help to control its migration from oral to the gastric compartment and may be used as an adjuvant treatment option for its re-infection.

Ketamine exhibits anti-gastric cancer activity via induction of apoptosis and attenuation of PI3K/Akt/mTOR

INTRODUCTION

Gastric cancer (GC) is the most widespread type of cancer after lung and liver cancer in men and after breast cancer in women. Thus, the present study was intended to evaluate the effect of ketamine (KET) on gastric cancer cells.

MATERIAL AND METHODS

The effect of KET was analyzed in vitro by the MTT assay against human gastric cancer cell lines BGC-823, MKN-45 and MKN-28. The effect KET on apoptosis, cell migration and cell cycle arrest was also quantified. Western blot analysis was performed to estimate the effect of KET on apoptosis mediators and PI3K/AKT/mTOR pathway mediators. A mouse xenograft assay was also conducted to further confirm the anticancer activity.

RESULTS

KET causes reduction of cellular viability of BGC-823, MKN-45 and MKN-28, with a more significant effect against BGC-823 cells. The KET treatment showed a dose-dependent increase in apoptotic cells among BGC-823 cells. KET causes a significant dose-dependent decline in migration of treated cells. It causes induction of apoptosis mediated via the mitochondrial pathway, where it causes a decline in Bcl2 and mitochondrial cytochrome c level together with increase in expression of Bax, cytosolic cytochrome c and cytosolic apoptotic protease activating factor-1 (Apaf-1). The level of p-PI3K, p-mTOR, p-GSK3β and p-AKT was found to be downregulated in a dose-dependent manner in KET-treated cells. In a mouse xenograft model, KET causes a reduction in relative tumour volume and tumour weight.

CONCLUSIONS

Our results suggest that ketamine has the ability to inhibit progression of gastric cancer via induction of apoptosis and attenuation of PI3K/Akt/mTOR.

Helicobacter pylori Infection, Virulence Genes' Distribution and Accompanying Clinical Outcomes: The West Africa Situation

Data on Helicobacter pylori (H. pylori) infection and virulence factors in countries across West Africa are scattered. This systematic review seeks to present an update on the status of H. pylori infection focusing on prevalence rate, distribution of virulent genes, and their link to clinical outcomes across countries in the western part of Africa. This information is expected to broaden the knowledge base of clinicians and researchers regarding H. pylori infection and associated virulence factors in West African countries. Search Method. A comprehensive search of the scientific literature in PubMed and ScienceDirect was conducted using the search terms including “Helicobacter pylori infection in West Africa”. Databases were sourced from January 1988 to December 2018. Results. Data on the incidence of H. pylori infection and related pathological factors were found for some countries, whereas others had no information on it. Smoking, alcohol, exposure to high levels of carcinogens and diet were reported to be involved in the pathogenesis of gastroduodenal diseases and gastric cancer. Besides the environmental factors and genetic characteristics, there are important characteristics of H. pylori such as the ability to infect, replicate, and persist in a host that have been associated with the pathogenesis of various gastroduodenal diseases. Concluding Remarks. This systematic search has provided information so far available on H. pylori virulence factors and clinical outcomes in West Africa. Accordingly, this piece has identified gaps in the body of knowledge highlighting the need for more studies to clarify the role of H. pylori virulence factors and associated clinical outcomes in the burden of this bacterial infection in West Africa, as data from these countries do not give the needed direct relation.

Helicobacter pylori infection and inflammatory bowel disease: a crosstalk between upper and lower digestive tract

Helicobacter pylori has coexisted with humans for approximately 60,000 years and greater than 50% of the global population is infected with H. pylori. H. pylori was successfully cultured in vitro in 1983 and studies of H. pylori have achieved substantial advances over the last 35 years. Since then, H. pylori has been characterized as the primary pathogenic factor for chronic gastritis, peptic ulcer, and gastric malignancy. Numerous patients have received H. pylori eradication treatment, but only 1-2% of H. pylori-infected individuals ultimately develop gastric cancer. Recently, numerous epidemiological and basic experimental studies suggested a role for chronic H. pylori infection in protecting against inflammatory bowel disease (IBD) by inducing systematic immune tolerance and suppressing inflammatory responses. Here we summarize the current research progress on the association between H. pylori and IBD, and further describe the detailed molecular mechanism underlying H. pylori-induced dendritic cells (DCs) with the tolerogenic phenotype and immunosuppressive regulatory T cells (Tregs). Based on the potential protective role of H. pylori infection on IBD, we suggest that the interaction between H. pylori and the host is complicated, and H. pylori eradication treatment should be administered with caution, especially for children and young adults.

Genome-Wide Association of Genetic Variation in the PSCA Gene with Gastric Cancer Susceptibility in a Korean Population

PURPOSE

Half of the world's gastric cancer cases and the highest gastric cancer mortality rates are observed in Eastern Asia. Although several genome-wide association studies (GWASs) have revealed susceptibility genes associated with gastric cancer, no GWASs have been conducted in the Korean population, which has the highest incidence of gastric cancer.

Materials and Methods

We performed genome scanning of 450 gastric cancer cases and 1,134 controls via Affymetrix Axiom Exome 319 arrays, followed by replication of 803 gastric cancer cases and 3,693 healthy controls.

RESULTS

We showed that the rs2976394 in the prostate stem cell antigen (PSCA) gene is a gastriccancer-susceptibility gene in a Korean population, with genome-wide significance and an odds ratio (OR) of 0.70 (95% confidence interval [CI], 0.64 to 0.77). A strong linkage disequilibrium with rs2294008 was also found, indicating an association with susceptibility. Individuals with the CC genotype of the PSCA gene showed an approximately 2-fold lower risk of gastric cancer compared to those with the TT genotype (OR, 0.47; 95% CI, 0.39 to 0.57). The effect of the PSCA gene on gastric cancer was more prominent in the female population and for diffuse type gastric cancer.

CONCLUSION

Our result confirmed that the PSCA gene may be the most important susceptibility gene for gastric cancer risk in a Korean population.

Lessons learnt from the epidemiology of Helicobacter pylori infection in Malaysia: JGHF Marshall and Warren Lecture 2017

The study of Helicobacter pylori in Malaysia has given several important insights into the epidemiology of the infection and pathogenesis of disease. Malaysia has a multiracial Asian population with three major Asian races living together-Malay, Chinese, and Indian. Races remain fairly distinct because of a paucity of interracial marriages. The "Racial Cohort Hypothesis" proposes that the infection occurs within racial groups rather than between. As such, the high prevalence among Indians (> 50%) and Chinese (40-50%) reflects the high prevalence in their countries of origin even though migration had taken place more than two generations before. The Malays have a comparatively low prevalence of about 10-20%. Despite the high prevalence of H. pylori, the Indians have a low gastric cancer incidence of less than 10 per 100 000 per year. This is in contrast to the Chinese who has an incidence in excess of 20 per 100 000 per year. We have called this the "Indian Enigma." The reason for this enigma is unclear and is the result of interaction between bacterial virulence factors, host susceptibility, and environmental factors. Phylogenetically, Chinese bacterial strains are distinct from Indians and Malays and are predominantly hpEastAsia/hsp EAsia. CagA EPIYA motifs among Chinese belong predominantly to the more virulent ABD motif. There is no clear distinguishing profile among host genetic factors. Environmental factors particularly diet may play an important role. Indians consume chilies and curries, which may be gastro protective, whereas Chinese consume more preserved and salted foods, which are thought to be carcinogenic.

Gastric cancer in Latin America

Every year, cancer affects more than one million Latin Americans. The increasing incidence of cancer could be secondary to an aging population, westernization of life style, and urbanization. LA has among the highest incidence rates of gastric cancer, compared to other countries. In this review, different studies on gastric cancer and its relation with risks factors, such as infections, diet and life styles typical of LA, besides the different molecular alterations of that specific population (mainly at a genetic polymorphism level) are analyzed. An exhaustive research was made in PubMed, MEDLINE and Embase of the most relevant studies conducted in the last 27 years (1990-2017) in LA.

The role of the microbiome and the use of probiotics in gastrointestinal disorders in adults in the Asia-Pacific region - background and recommendations of a regional consensus meeting

The Asia-Pacific region is diverse, with regard to ethnicity, culture, and economic development incorporating some of the world's least and most developed nations. Gastrointestinal diseases are common in the Asia-Pacific region, and their prevalence, presentation, and management vary considerably within the region. There is growing evidence for an important role for the human gut microbiota in gastrointestinal health. As a consequence, geographic variations in the composition of the gut microbiota may contribute to variations in both the prevalence and response to therapy of specific diseases. Probiotics have been proposed as a valuable option in the prevention and treatment of a number of gastrointestinal illnesses, but the quality of available evidence to support their efficacy is variable. A meeting of international experts in adult and pediatric gastroenterology was held at the Sorbonne University, Paris, France, on April 11 and 12, 2016, to discuss current evidence supporting the use of probiotics in gastrointestinal disorders in the Asia-Pacific region. This article provides an overview of the discussions held at this meeting and recommends the formation of an Asia-Pacific Consortium on Gut Microbiota similar to those established in Europe and North America.

Can Diet Modulate Helicobacter pylori-associated Gastric Pathogenesis? An Evidence-Based Analysis

Helicobacter pylori is involved in the pathogenesis of gastritis, peptic ulcer, and gastric cancer. The infection is prevalent in more than half of the world's population. Although the infection may lead to detrimental consequences, still the majority of the infected individuals only develop mild gastritis. Several factors are behind this paradoxical outcome including virulence of the infecting H. pylori strains, genetic background of the host, and factors related to lifestyle such as dietary habits. Among these, lifestyle including dietary factors was not in the limelight, until recently, as one of the important factors that could modulate H. pylori-linked gastric diseases. This review is directed to gather and elucidate the role of dietary components in augmenting or attenuating pathological processes initiated by H. pylori. Available evidence strongly supports the notion that the diet may play a critical role in defining the final outcome of H. pylori infection particularly if certain dietary components are taken on a regular basis for a long time. Despite a recent surge in research related to the role of dietary ingredients, further studies involving large-scale clinical trials are required to gain a better understanding of the precise role played by the dietary ingredients in H. pylori-associated pathogenesis.

Cancer research priorities and gaps in Iran: the influence of cancer burden on cancer research outputs between 1997 and 2014

OBJECTIVES

As a developing country, Iran is experiencing the increasing burden of cancers, which are currently the third leading cause of mortality in Iran. This study aims to demonstrate that cancer research in Iran concentrates on the cancer research priorities based on the global burden of disease (GBD) reports.

STUDY DESIGN

Descriptive evaluation of all cancers disability-adjusted life years (DALYs) was performed using GBD data. Also a comprehensive search was conducted using cancer-associated keywords to obtain all cancer-related publications from Iran, indexed in Web of Science.

METHOD

Multiple regression analysis and correlation coefficients (R²) were used to evaluate the possible associations between cancer research publications and GBD.

RESULTS

During 1996-2014, the majority of cancer-related publications in Iran focused on breast cancer, leukaemia and stomach cancer, respectively. This study found hypothetical correlations between cancer publications in Iran in line with the burden of cancer as reported by GBD. Particularly, correlations between years lived with disability (YLD) and cancer-related publications were more obvious.

CONCLUSION

This study introduces a new outline in setting cancer research priorities in the region.

Fermented Foods: Are They Tasty Medicines for Helicobacter pylori Associated Peptic Ulcer and Gastric Cancer?

More than a million people die every year due to gastric cancer and peptic ulcer. Helicobacter pylori infection in stomach is the most important reason for these diseases. Interestingly, only 10-20% of the H. pylori infected individuals suffer from these gastric diseases and rest of the infected individuals remain asymptomatic. The genotypes of H. pylori, host genetic background, lifestyle including smoking and diet may determine clinical outcomes. People from different geographical regions have different food habits, which also include several unique fermented products of plant and animal origins. When consumed raw, the fermented foods bring in fresh inocula of microbes to gastrointestinal tract and several strains of these microbes, like Lactobacillus and Saccharomyces are known probiotics. In vitro and in vivo experiments as well as clinical trials suggest that several probiotics have anti-H. pylori effects. Here we discuss the possibility of using natural probiotics present in traditional fermented food and beverages to obtain protection against H. pylori induced gastric diseases.

Intervention effect of pinelliae decoction for purging stomach-fire on malignant transformation of bone marrow mesenchymal stem cells in the gastric cancer microenvironment

OBJECTIVE

The study aimed to simulate the microenvironment of gastric cancer to promote the malignant transformation of bone marrow mesenchymal stem cells (BMSCs) and further evaluate the effect of Pinelliae Decoction for Purging Stomach-Fire and its disassembled prescriptions on BMSCs.

METHODS

Transwell co-culture was performed on the human gastric cancer cell strains BGC-823 and BMSCs to simulate the microenvironment of gastric cancer. The drug-containing serum prepared by Pinelliae Decoction for Purging Stomach-Fire and its disassembled prescriptions was used, and its influence on BMSCs with malignant transformation was observed.

RESULTS

BMSCs were harvested successfully from the rat bone marrow, and flow cytometer identification indicated that CD44+/CD34- cells accounted for 70.64%. The co-culture of BGC-823 cells can induce malignant transformation of BMSCs. And the drug-containing serum can induce G2 phase arrest, inhibit cell proliferation, simultaneously inhibit TERT and c-myc expression, lower the cellular ability of chemotactic migration, inhibit the tumor-forming ability of BGC-823 in nude rats and promote the tumor apoptosis.

CONCLUSION

The effective components of Pinelliae Decoction for Purging Stomach-Fire in gastric cancer treatment are pinelliae and dried ginger, and the main acting mechanism is to inhibit tumor cell proliferation and chemotactic migration and promote apoptosis.

Helicobacter pylori associated Asian enigma: Does diet deserve distinction?

Helicobacter pylori (H. pylori) is one of the most widespread infections in humans worldwide that chronically infects up to 50% of the world’s population. The infection is involved in the pathogenesis of chronic active gastritis, peptic ulcer, mucosa-associated lymphoid tissue lymphoma and gastric cancer, therefore, it has been classified as class I definite carcinogen by the World Health Organization. Despite the established etiological role of H. pylori, its actual distribution and association with related diseases is controversial and there is a large intercountry variation especially among Asian countries. H. pylori infection is more frequent in developing countries like India, Pakistan, and Bangladesh as compared to developed Asian countries like Japan, China and South Korea. However, the frequency of gastric cancer is comparatively lower in India, Pakistan, and Bangladesh with that of Japan, China and South Korea. Such phenomenon of clinical diversity, defined as enigma, is judged by genetic variability of the infecting H. pylori strains, differences in the host genetic background in various ethnic groups, and environmental factors such as dietary habits. Most of the studies have so far focused on the bacterial factor while environmental issues, including dietary components, were not given due attention as one of the factors related with H. pylori associated gastric carcinogenesis. The dietary factor has been suggested to play an important role in H. pylori related carcinogenesis, and in this respect several studies have corroborated the intake of various dietary components as modulatory factors for gastric cancer risk. In this review, such studies, from in vitro experiments to clinical trials, are being focused in detail with respect to enigma associated with H. pylori. It may be conceivably concluded from the available evidence that dietary factor can be a game changer in the scenario of Asian enigma, particularly in high risk population infected with virulent H. pylori strains, however further affirmation studies are desperately needed to achieve conclusive outcomes.

Anti-Inflammatory Effects of Capsaicin and Piperine on Helicobacter pylori-Induced Chronic Gastritis in Mongolian Gerbils

BACKGROUND

Spices have been used for thousands of years, and recent studies suggest that certain spices confer beneficial effects on gastric disorders. The purpose of this study was to evaluate possible chemopreventive effects of spice-derived compounds on Helicobacter pylori (H. pylori)-induced gastritis.

METHODS

We examined the inhibitory effects of curcumin, capsaicin, and piperine on H. pylori in vitro by determining the colony-forming units and real-time RT-PCR in H. pylori stimulated AGS gastric cancer cells. For in vivo analysis, 6-week-old SPF male Mongolian gerbils were infected with H. pylori, fed diets containing 5000 ppm curcumin, 100 ppm capsaicin, or 100 ppm piperine, and sacrificed after 13 weeks.

RESULTS

All three compounds inhibited in vitro proliferation of H. pylori, with curcumin being the most effective. Infiltration of neutrophils and mononuclear cells was suppressed by piperine both in the antrum and corpus of H. pylori-infected gerbils. Capsaicin also decreased neutrophils in the antrum and corpus and mononuclear cell infiltration and heterotopic proliferative glands in the corpus. mRNA expression of Tnf-α and formation of phospho-IκB-α in the antrum were reduced by both capsaicin and piperine. In addition, piperine suppressed expression of Il-1β, Ifn-γ, Il-6, and iNos, while H. pylori UreA and other virulence factors were not significantly attenuated by any compounds.

CONCLUSION

These results suggest that capsaicin and piperine have anti-inflammatory effects on H. pylori-induced gastritis in gerbils independent of direct antibacterial effects and may thus have potential for use in the chemoprevention of H. pylori-associated gastric carcinogenesis.

The Gastric Mucosa from Patients Infected with CagA+ or VacA+ Helicobacter pylori Has a Lower Level of Dual Oxidase-2 Expression than Uninfected or Infected with CagA-/VacA- H. pylori

BACKGROUND

Helicobacter pylori (H. pylori) is a well-recognized gastroduodenal pathogen and class I carcinogen. Dual oxidase-2 (DUOX2), a member of NADPH oxidase family, has several critical physiological functions, including thyroid hormone biosynthesis and host mucosal defense.

AIM

To investigate the effect of H. pylori infection on DUOX2 gene expression in human stomach.

MATERIALS AND METHODS

The biopsies were obtained from patients who underwent endoscopic diagnosis. The patient serum was assayed for two virulence factors of H. pylori, CagA IgG and VacA. The inflammation in gastric mucosa was analyzed with histology. Real-time quantitative PCR was used to detect the expression of three members of NADPH oxidase, NOX1, NOX2, and DUOX2, as well as lactoperoxidase (LPO) in the gastric mucosa. NOX2, DUOX2, and myeloperoxidase (MPO) protein levels were quantified by Western blots or immunohistochemistry.

RESULTS

The H. pylori-infected gastric mucosa had more severe inflammation than uninfected samples. However, the expression of DUOX2 mRNA and protein was lower in gastric mucosa of patients with H. pylori infection compared to the uninfected. Among the H. pylori-infected patients, those having CagA IgG or VacA in the serum had lower DUOX2 expression levels than those infected with H. pylori without either virulence factor. The NOX2 and MPO levels were higher in those patients infected with H. pylori irrespective of the virulence factors than those uninfected patients. NOX1 and LPO mRNA were undetectable in the gastric mucosa.

CONCLUSION

CagA+ or VacA+ H. pylori in the stomach of patients may suppress DUOX2 expression to promote its own survival. Increased NOX2 could not eliminate H. pylori infection.

Association between pro-(IL-8) and anti-inflammatory (IL-10) cytokine variants and their serum levels and H. pylori-related gastric carcinogenesis in northern India

BACKGROUND

Interleukin (IL)-8 -251 T/A and IL-10 (-1082 G/A and -819/592 C/T) polymorphisms and their expression may influence gastritis, atrophy, intestinal metaplasia (IM) and gastric cancer (GC) following H. pylori infection.

METHODS

Genotyping of these genes was performed (ASO-PCR) in 200, 182 and 250 with GC, functional dyspepsia (FD) and healthy controls (HC), respectively. Anti-H. pylori IgG-antibody was tested in all and serums IL-8 and IL-10 were measured randomly in 60 subjects of each group by ELISA.

RESULTS

Pro-(IL-8)-251 AA and anti-inflammatory (IL-10)-819 TT genotypes were commoner among GC than HC (p = 0.023, OR 1.86 [1.09-3.2] and p = 0.020, OR 2.0 [1.11-3.5]) but comparable with FD. IL-8 AA and IL-10-819 T allele carriage was also commoner in H. pylori-infected GC than HC (p = 0.011, OR 2.47 [1.23-5.0], and p = 0.018, OR 2.3 (1.16-4.59). IL-10-1082 G/A genotype and haplotypes (ACC, GCC, ATA and GTA) were comparable in all groups. Circulating levels of IL-8 and IL-10 were higher among GC than HC but comparable to FD (IL-8; 57.64 [6.44-319.46] vs. 54.35 [4.24-318.96] and 26.33 [4.67-304.54] pg/ml, p < 0.001 and IL-10; 15.47 [1.01-270.87] vs. 12.28 [0.96-64.88] and 3.79 [1.24-56.65], p < 0.001 for GC vs. HC). IL-8/IL-10 ratio was lower among GC than HC but higher than FD (3.7 [0.18-38.41] vs. 6.59 [0.98-130.2], p < 0.001 and 4.22 [0.15-61.4], p < 0.01). Circulating levels of IL-8, IL-10 and IL-8/lL-10 ratios were different among H. pylori-infected and non-infected GC than HC (p < 0.001, p < 0.001 and p < 0.01).

CONCLUSIONS

Pro-(IL-8)-251 T/A and anti-inflammatory (IL-10)-819 C/T gene polymorphisms and their circulating levels may play a role in H. pylori-associated gastric carcinogenesis in northern India.

Overall Survival Is Impacted by Birthplace and Not Extent of Surgery in Asian Americans with Resectable Gastric Cancer

Survival from gastric cancer in the USA still lags behind Asia. Genetic, environmental, and tumor biology differences, along with extent of surgery have been implicated. Our aim was to evaluate survival outcomes in Asian-American gastric cancer patients undergoing surgical resection by comparing place of birth and clinicopathologic characteristics (including evaluation of 15 lymph nodes).The Surveillance, Epidemiology, and End Results database was queried to identify patients treated surgically for gastric cancer with curative intent in the USA (2000-2010). US-born versus foreign-born Asian-American patients were analyzed for survival. Secondary comparison was made to non-Asian patients. Stage IV and non-surgical patients were excluded. Of 10,089 patients identified, 1467 patients were Asian: 271 were born in the USA, and 1196 were born outside the USA. Median survival was 32 months for non-Asians and 29 months for US-born Asians versus 61 months for Asian immigrants (p < 0.001). On multivariable analysis of overall survival in Asian patients, only US birthplace, older age, and higher stage yielded a significantly poorer outcome. Asian-American patients have a worse prognosis if born in the USA. Anatomic and surgical differences do not explain this disparity; environmental factors may be responsible.

Significant Association of Interleukin4 Intron 3 VNTR Polymorphism with Susceptibility to Gastric Cancer in a South Indian Population from Telangana

BACKGROUND

Gastric cancer (GC) is the fifth most common malignancy and remains a considerable public health burden worldwide. Genetic variations in genes encoding cytokines and their receptors influence the intensity of the Helicobacter pylori associated inflammatory response, which may contribute to individual differences in the outcome and severity of the disease. Interleukin4 is a typical pleiotropic T helper 2 (Th2) cytokine and is a critical mediator of Th1/Th2 balance. It is involved in the regulation of inflammation-mediated carcinogenesis in human organs, including gastric cancer.

OBJECTIVE

The present retrospective case control study was undertaken to evaluate the association of IL4 intron 3 VNTR polymorphism with the susceptibility to GC in a south Indian population from Telangana state.

MATERIALS AND METHODS

A total of 182 patients with diagnosed GC and 326 randomly selected healthy controls were enrolled in the present study. Genomic DNA was extracted from peripheral leukocytes and genotyping was determined by PCR-based assay. Association between genotypes and gastric cancer was examined by unconditional logistic regression analysis.

RESULT

The variant 3R/2R and 2R/2R genotypes of IL4 exon3 VNTR polymorphism had about 1.9 fold and 3fold increased GC risk, respectively, when compared with 3R/3R genotype [3R/2R vs. 3R/3R: adjusted odds ratio (AOR) = 1.90, 95% confidence interval (CI) = 1.23-2.95 P = 0.004 and 2R/2R vs. 3R/3R: AOR (95%CI) = 2.96 (1.29-6.82), P = 0.011]. Furthermore, a significant increased risk of GC was found for the 2R allele carriers (3R/2R + 2R/2R) compared with the 3R/3R genotype (AOR (95%CI) = 2.04 (1.35-3.10), P = <0.000). The IL4 2R allele frequency was 0.28 among the GC group and 0.18 among the controls, and the difference was statistically significant (P = <0.000).

CONCLUSION

The present study revealed an association of 2R allele and 2R carrier genotypes in the etiopathogenesis of GC in south Indian population.

Association between pro-(IL-8) and anti-inflammatory (IL-10) cytokine variants and their serum levels and H. pylori-related gastric carcinogenesis in northern India

BACKGROUND

Interleukin (IL)-8 -251 T/A and IL-10 (-1082 G/A and -819/592 C/T) polymorphisms and their expression may influence gastritis, atrophy, intestinal metaplasia (IM) and gastric cancer (GC) following H. pylori infection.

METHODS

Genotyping of these genes was performed (ASO-PCR) in 200, 182 and 250 with GC, functional dyspepsia (FD) and healthy controls (HC), respectively. Anti-H. pylori IgG-antibody was tested in all and serums IL-8 and IL-10 were measured randomly in 60 subjects of each group by ELISA.

RESULTS

Pro-(IL-8)-251 AA and anti-inflammatory (IL-10)-819 TT genotypes were commoner among GC than HC (p = 0.023, OR 1.86 [1.09-3.2] and p = 0.020, OR 2.0 [1.11-3.5]) but comparable with FD. IL-8 AA and IL-10-819 T allele carriage was also commoner in H. pylori-infected GC than HC (p = 0.011, OR 2.47 [1.23-5.0], and p = 0.018, OR 2.3 (1.16-4.59). IL-10-1082 G/A genotype and haplotypes (ACC, GCC, ATA and GTA) were comparable in all groups. Circulating levels of IL-8 and IL-10 were higher among GC than HC but comparable to FD (IL-8; 57.64 [6.44-319.46] vs. 54.35 [4.24-318.96] and 26.33 [4.67-304.54] pg/ml, p < 0.001 and IL-10; 15.47 [1.01-270.87] vs. 12.28 [0.96-64.88] and 3.79 [1.24-56.65], p < 0.001 for GC vs. HC). IL-8/IL-10 ratio was lower among GC than HC but higher than FD (3.7 [0.18-38.41] vs. 6.59 [0.98-130.2], p < 0.001 and 4.22 [0.15-61.4], p < 0.01). Circulating levels of IL-8, IL-10 and IL-8/lL-10 ratios were different among H. pylori-infected and non-infected GC than HC (p < 0.001, p < 0.001 and p < 0.01).

CONCLUSIONS

Pro-(IL-8)-251 T/A and anti-inflammatory (IL-10)-819 C/T gene polymorphisms and their circulating levels may play a role in H. pylori-associated gastric carcinogenesis in northern India.

Allergies, Helicobacter pylori and the continental enigmas

Helicobacter pylori, a gastric pathogen, is known to be associated with gastric and duodenal ulcers, and is also a strong risk factor for the development of gastric cancer and lymphoma of the mucosal-associated lymphoid tissue. Ordinarily, this should make a strong case for its eradication at par with any other infectious disease. However, the unique biology of H. pylori and the complexity of its interactions with humans, its only known natural host, do not permit the recommendation of unambiguous preventive and therapeutic measures. Moreover, this organism has co-evolved with humans as a practically universal member of the natural gastric microbiota over at least 100,000 years. H. pylori persists for a lifetime in mostly asymptomatic hosts, and causes clinical disease only in a minority of infections. Therefore, its potential contribution to the maintenance of human immune homeostasis, as is the case with the better-studied members of the intestinal microbiota, is certainly worthy of serious investigation. In this paper, we summarize some interesting and often anecdotal data drawn from recent studies, and examine their significance in the context of the hygiene hypothesis. We also examine whether the lower incidence of gastric cancer over large parts of the world in spite of a high prevalence of infection (the Asian and African enigmas) may be re-interpreted in terms of the hygiene hypothesis. Finally, it is suggested that an evolutionary-ecological approach to the study of H. pylori infection may help in the formulation of strategies for the management of this infection. This may well be an infectious disease wherein medical interventions may have to be personalized to ensure optimal outcomes.

A Patient with a Large Gastric Tumor and Protein-Losing Gastroenteropathy Successfully Treated with Neoadjuvant TS-1 Combined with CDDP Therapy

Gastric cancer with protein-losing gastroenteropathy is relatively rare worldwide. The most important problem for the treatment of these patients is their low nutritional status and protein level, which can cause severe postoperative complications. We report a 49-year-old Japanese female with a large gastric tumor and protein-losing gastroenteropathy successfully treated with neoadjuvant TS-1 combined with CDDP therapy. She had a type 5 tumor with partially cauliflower-like appearance. Her blood chemistry revealed low serum total protein (3.3 g/dl) and low albumin (1.7 g/dl). She was additionally diagnosed with protein-losing gastroenteropathy based on ^99mTc-human serum albumin scintigraphy. Initial neoadjuvant chemotherapy decreased the size of the tumor and led to a marked improvement in her serum protein levels. She then underwent a total gastrectomy and lymph node dissection (D2) with a combined resection of the spleen and gallbladder. Therefore, neoadjuvant chemotherapy may provide a safe treatment before definitive surgery for gastric cancer with protein-losing gastroenteropathy.

Age, period, and cohort effects on gastric cancer mortality

BACKGROUND

The incidence of gastric cancer varies both within and among populations and can change rapidly without a corresponding decline in Helicobacter pylori prevalence. Here, we describe the changes in gastric cancer mortality in Japan in relation to age-period-cohort effects as well as the decline in H. pylori prevalence.

METHODS

We used data from Japanese for men and women aged 30-94 for birth years 1875-1970 (calendar time 1950-2000) to observe the age, period and cohort effects on gastric cancer mortality rates. Additionally, we used Poisson regression to simultaneously adjust for concurrent age, period and cohort effects as well as for declining H. pylori prevalence in the Japanese population.

RESULTS

There was an approximate 60 % decline in gastric cancer mortality between 1965 and 1995. Detailed age, period and cohort analyses and Poisson regression analysis showed these factors interact in complex ways, analyses focused on one or two of these effects, such as birth cohort without considering concurrent age and period would obscure important interactions that affected different age groups at different times to produce this composite effect.

CONCLUSION

The underlying complexity in population-disease dynamics requires population-specific descriptions of trends using multiple methods to provide an in-depth analysis while simultaneously allowing for necessary statistical adjustments as well as identification of interactions. More thorough descriptions of the population-specific general trends in relation to changes in the population structure (age-period-cohort) enable better prevention and health care policy planning, and further, the descriptions enable hypothesis generation regarding causes of population-specific disease patterns.

SNPs of excision repair cross complementing group 5 and gastric cancer risk in Chinese populations

We conducted a case-control study to determine the association between several potential SNPs of excision repair cross complementing group 5 (XPG) and gastric cancer susceptibility, and roles of XPG polymorphisms in combination with H.pylori infection in determining risk of gastric cancer. In our study, we collected 337 newly diagnosed gastric cancer cases and 347 health controls. Three SNPs of XPG, rs2296147T>C, rs2094258C>T and rs873601G>A, were genotyped using the Taqman real-time PCR method with a 7900 HT sequence detector system. H. pylori infection was diagnosed by ELISA. By multivariate logistic regression analysis, the rs2296147 CC genotype was associated with a decreased risk of gastric cancer (OR=0.52, 95% CI=0.27-0.97), and rs2094258 TT was associated with elevated risk (OR=2.13, 95% CI=1.22-3.35). Positive H.pylori individuals with rs2094258 TT genotypes demonstrated increased risk of gastric cancer (OR=2.13, 95% CI=1.22-3.35), while rs2296147 CC was associated with lower risk among patients with negative H.pylori (OR=0.45, 95%CI=0.22-0.89). Our findings suggested that XPG polymorphisms might contribute to risk of gastric cancer among Chinese populations, but the effect needs to be further validated by larger sample size studies.

Helicobacter pylori infection: New pathogenetic and clinical aspects

Helicobacter pylori (H. pylori) infects more than half of the world’s human population, but only 1% to 3% of infected people consequently develop gastric adenocarcinomas. The clinical outcome of the infection is determined by host genetic predisposition, bacterial virulence factors, and environmental factors. The association between H. pylori infection and chronic active gastritis, peptic ulcer disease, gastric cell carcinoma, and B cell mucosa-associated lymphoid tissue lymphoma has been well established. With the exception of unexplained iron deficiency anemia and idiopathic thrombocytopenic purpura, H. pylori infection has no proven role in extraintestinal diseases. On the other hand, there is data showing that H. pylori infection could be beneficial for some human diseases. The unpredictability of the long-term consequences of H. pylori infection and the economic challenge in eradicating it is why identification of high-risk individuals is crucial.

Genetic polymorphism of cytochrome P450 (CYP) 1A1, CYP1A2, and CYP2E1 genes modulate susceptibility to gastric cancer in patients with Helicobacter pylori infection

BACKGROUND

Activity of cytochrome P450 (CYP), a polymorphic carcinogen-activating enzyme, is exaggerated following Helicobacter pylori infection. We studied the role of CYP2E1, CYP1A2 (rs762551), and CYP1A1 (rs4646903) polymorphisms in association with H. pylori infection in gastric carcinogenesis.

METHODS

Genotyping of CYP2E1 (96-bp insertion), CYP1A2 (164A to C), and CYP1A1 (3801C to T) was carried out in 88, 76, 53, and 170 patients with gastric cancer (GC), functional dyspepsia (FD), peptic ulcer (PU), and healthy controls (HC), respectively. Serum IgG antibody (all subjects), rapid urease test, and histology (GC, FD, and PU patients) were used to test for H. pylori.

RESULTS

CYP2E1 gene polymorphism was more common among patients with GC than HC and PU [48/88 (54.5 %) vs. 67/170 (39.4 %); OR 1.9, 95 % CI 1.1-3.2, p = 0.016) and [PU 18/53 (34 %); OR 2.3 (1-4.7), p = 0.02]. CYP1A2 CC or CT genotypes was lower among patients with GC than HC [50/88 (56.8 %) vs. 120/170 (70.6 %); OR 0.54 (0.31-0.92), p = 0.023]. CYP1A1 polymorphism and CYP1A1-CYP1A2 haplotypes were comparable among different groups. CYP2E1 was also more common in patients with GC than HC and PU in the absence of H. pylori [33/60 (55 %) vs. 19/52 (36.5 %); OR 4 (1.5-11.4), p = 0.007 and PU 7/22 (31.8 %); OR 3.4 (1-11.6), p = 0.05]. CYP1A1 (CT + TT) was more common in patients with GC than PU in presence of H. pylori [17/26 (65.4 %) vs. 11/29 (38 %); OR 3.0 (1.03-9.3), p = 0.045].

CONCLUSIONS

The presence of CYP2E1 (96-bp insertion) is associated with increased risk of GC even in absence of H. pylori. CYP1A2 CC or CT is associated with reduced risk of GC.

Oxidative DNA damage as a potential early biomarker of Helicobacter pylori associated carcinogenesis. Pathol Oncol Res. 2014;20:839-846. [PMID: 24664859 DOI: 10.1007/s12253-014-9762-1]

Helicobacter pylori infection is an established risk factor for gastritis, gastric ulcer, peptic ulcer and gastric cancer. CagA +ve H. pylori has been associated with oxidative DNA damage of gastric mucosa but their combined role in the development of gastric cancer is still unknown. Here we compare the combined expression of cagA and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in normal, gastritis and gastric cancer tissues. Two hundred gastric biopsies from patients with dyspeptic symptoms, 70 gastric cancer tissue samples and 30 gastric biopsies from non-dyspeptic individuals (controls) were included in this study and 8-OHdG was detected by immunohistochemistry (IHC). Histological features and the presence of H. pylori infection were demonstrated by Hematoxylin and Eosin (HE), Giemsa and alcian blue-periodic acid-Schiff ± diastase (AB-PAS ± D) staining. DNA was extracted from tissues and polymerase chain reaction (PCR) performed to determine the presence of ureaseA and cagA genes of H. pylori. The results showed the presence of H. pylori in 106 (53 %) gastric biopsies out of 200 dyspeptic patients, including 70 (66 %) cases of cagA + ve H. pylori. The presence of cagA gene and high expression of 8-OHdG was highly correlated with severe gastric inflammation and gastric cancer particularly, in cases with infiltration of chronic inflammatory cells (36.8 % cagA + ve, 18 %), neutrophilic activity (47.2 %, 25.5 %), intestinal metaplasia (77.7 %, 35.7 %) and intestinal type gastric cancer (95 %, 95.4 %) (p ≤ 0.01). In conclusion, H. Pylori cagA gene expression and the detection of 8-OHdG adducts in gastric epithelium can serve as potential early biomarkers of H. Pylori-associated gastric carcinogenesis.

Epidemiology of gastric cancer in the gangetic areas of west bengal

There is marked geographical variation in the distribution and incidence of stomach cancer. We tried here to describe the pattern of relationships of age, sex, religion distribution, symptom profile, histological subtypes and Helicobacter pylori (H. pylori) infection with gastric cancer in Gangetic West Bengal. This study was done over a period of five years (2006–2010). The patients residing in the Gangetic areas of West Bengal presenting with upper gastrointestinal symptoms underwent UGI endoscopy. Among gastric cancer patients, demographic characteristics, symptomatology, macroscopic and histologic lesions and H. pylori status were analyzed. At confidence level 95%, “Z” and “P” value were calculated to find significance. Among 23851 patients underwent UGI endoscopy, 14106 were males, 9745 females, 17889 Hindus and 5962 Muslims. Among 462 gastric cancer patients, Male : Female 2.7 : 1, Hindus : Muslim 3 : 1, abdominal pain, indigestion, and weight-loss were commonest presentations. Antrum was the commonest site whereas ulceroproliferative type was commonest type. H. pylori positivity was 80.89% in adenocarcinoma with statistically significant relation with intestinal type. In future, our target will be to modify risk factors; it will need further demographic studies and analysis, so that we can detect it earliest.

Quantitative assessment of the influence of glutathione S-transferase T1 null variant on gastric cancer risk

Glutathione S-transferase T1 (GSTT1) catalyzes reactions between glutathione and lipophilic compounds with electrophilic centers, leading to neutralization of toxic compounds, xenobiotics, and products of oxidative stress. In the past decade, a number of case-control studies have been carried out to investigate the relationship between the GSTT1 null polymorphism and gastric cancer (GC), but the results have been inconclusive. To investigate this inconsistency, we performed a meta-analysis of 46 studies involving a total of 9012 GC cases and 14,215 controls for null variant of the GSTT1 gene to evaluate the effect of GSTT1 on genetic susceptibility for GC. Potential sources of heterogeneity including ethnicity, source of control, and sample size were also assessed. Overall, significantly increased GC risk was associated with GSTT1 null polymorphism with OR of 1.20 (95% CI, 1.10-1.32; P < 0.05). In the subgroup analysis by ethnicity, significantly increased risks were found in East Asians and Indians, while no significant associations were found among Caucasian, and Middle Eastern and African populations. By pooling data from 19 studies that considered combinations of GSTT1 and GSTM1 genotypes, a statistically significant increased risk for GC (OR = 2.04, 95% CI, 1.49-2.64; P < 0.05) was detected for individuals with dual deletion in both genes compared with positive genotypes. In addition, we found that cigarette smoking and alcohol drinking may modified the association of GSTT1 null genotypes with the risk of GC. In conclusion, this meta-analysis suggests that GSTT1 null polymorphism is associated with elevated GC risk, but these associations vary in different ethnic populations.

Association of microsomal epoxide hydrolase exon 3 Tyr113His and exon 4 His139Arg polymorphisms with gastric cancer in India

BACKGROUND

Microsomal epoxide hydrolase, an important phase II xenobiotic enzyme, exhibits polymorphisms at exon 3 (Tyr113His [T/C]) and exon 4 (His139Arg [A/G]), which modulate enzyme activity; this may affect susceptibility to cancers. We studied association between these polymorphisms and gastric cancer (GC).

METHODS

In a prospective study, 77 patients with GC, 50 with peptic ulcer, and 160 healthy controls (HC) were genotyped for exon 3 (PCR-RFLP followed by sequencing) and exon 4 (PCR-RFLP). Helicobacter pylori was considered to be present if two of three tests (histology, rapid urease test, and IgG antibody) were positive.

RESULTS

Tyr113His and His139Arg genotypes and haplotypes were comparable among groups. 113His carriers were commoner among H. pylori-negative patients with GC than HC (p-value = 0.019, odds ratio (OR) = 2.5, 95 % confidence interval (CI) = 1.2-5.4). Haplotype combination of exons 3 and 4 113Tyr-139Arg (TA) were associated with higher and reduced risk in patients with GC than HC in presence and absence of H. pylori (25 % vs. 11 %; p-value = 0.033, OR = 2.61, 95 % CI = 1.08-6.3 and 11.6 % vs. 28.7 %; p-value = 0.004, OR = 0.33, 95 % CI = 0.15-0.7, respectively).

CONCLUSIONS

Though 113Tyr-139Arg was associated with GC in presence of H. pylori, in its absence, it appeared to be protective. Exon 3, 113His, however, was associated with GC even in absence of H. pylori infection.

Genetic polymorphism of glutathione S-transferases M1 and T1, tobacco habits and risk of stomach cancer in Mizoram, India

AIM

The incidence of stomach cancer in Mizoram is highest in India. We have conducted a population based matched case-control study to identify environmental and genetic risk factors in this geographical area.

METHODS

A total of 102 histologically confirmed stomach cancer cases and 204 matched healthy population controls were recruited. GSTM1 and GSTT1 genotypes were determined by PCR and H. pylori infections were determined by ELISA.

RESULTS

Tobacco-smoking was found to be an important risk factor for high incidence of stomach cancer in Mizoram. Meiziol (local cigarette) smoking was a more important risk factor than other tobacco related habits. Cigarette, tuibur (tobacco smoke infused water) and betel nut consumption synergistically increased the risk of stomach cancer. Polymorphisms of GSTM1 and GSTT1 genes were not found to be directly associated with stomach cancer in Mizoram. However, they appeared to be effect modifiers. Persons habituated with tobacco smoking and/or tuibur habit had increased risk of stomach cancer if they carried the GSTM1 null genotype and GSTT1 non-null genotype.

CONCLUSION

Tobacco smoking, especially meiziol is the important risk factor for stomach cancer in Mizoram. GSTM1 and GSTT1 genes modify the effect of tobacco habits. This study is a first step in understanding the epidemiology of stomach cancer in Mizoram, India.

Glulathione-S-transferases gene polymorphism in prediction of gastric cancer risk by smoking and Helicobacter pylori infection status

AIM

To evaluate the association of glutathione S-transferases gene polymorphisms with the risk of gastric cancer, with reference to smoking and Helicobacter pylori infection.

METHODS

We conducted a 1:1 matched case-control study with 410 gastric cancer cases and 410 cancer-free controls. Polymorphisms of GSTM1, GSTT1 and GSTP1 were determined using PCR-CTPP.

RESULTS

The GSTM1 and GSTT1 null genotypes were significantly associated with the risk of gastric cancer after adjusting for potential confounding factors (OR=1.68, 95% CI=1.32-2.23 for null GSTM1, OR=1.73; 95% CI=1.24-2.13 for null GSTT1). The combination of null GSTM1 and null GSTT1 conferred an elevated risk (OR=2.54, 95% CI=1.55-3.39). However, no association was found for GSTP1 polymorphism The smoking modified the association of GSTM1 and GSTT1 null genotypes with the risk of gastric cancer.

CONCLUSION

GSTM1 and GSTT1 null genotypes are associated with increased risk of gastric cancer, and smoking modifies the association.

Association between the GSTP1 codon 105 polymorphism and gastric cancer risk: an updated meta-analysis

OBJECTIVE

The current meta-analysis was performed to address a more accurate estimation of the association between glutathione S-transferase P1 (GSTP1) codon 105 polymorphism and risk of gastric cancer (GC), which has been widely reported with conflicting results.

METHODS

A comprehensive literature search was conducted to identify all the relevant studies. Fixed or random effect models were selected based on the heterogeneity test. Publication bias was estimated using Begg's funnel plots and Egger's regression test.

RESULTS

A total of 20 studies containing 2,821 GC cases and 6,240 controls were finally included in the analyses. Overall, no significant association between GSTP1 polymorphism and GC risk was observed in worldwide populations. However, subgroup analysis stratified by ethnicity showed that GSTP1 polymorphism was significantly associated with increased risk of GC in Asians (G vs. A, OR = 1.273, 95%CI=1.011-1.605; GG vs. AA, OR=2.103, 95%CI=1.197- 3.387; GG vs. AA+AG, OR =2.103, 95%CI=1.186-3.414). In contrast, no significant association was found in Caucasians in any genetic models, except for with AG vs. AA (OR=0.791, 95%CI=0.669-0.936). Furthermore, the GSTP1 polymorphism was found to be significantly associated with GC in patients with H. pylori infection and in those with a cardiac GC. Subgroup analysis stratified by Lauren's classification and smoking status showed no significant association with any genetic model. No studies were found to significantly influence the pooled effects in each genetic mode, and no potential publication bias was detected.

CONCLUSIONS

This meta-analysis suggested that the GSTP1 polymorphism might be associated with increased risk of GC in Asians, while GSTP1 heterozygote genotype seemed to be associated with reduced risk of GC. Since potential confounders could not be ruled out completely, further studies are needed to confirm these results.

Role of tumor necrosis factor-α -308 G/A promoter polymorphism in gastric cancer

BACKGROUND/AIM

Gastric cancer (GC) is the fourth most common cancer and the second most common cause of cancer death world-wide after lung cancer. It is a multifactorial disease with the involvement of both genetic and environmental risk factors. Genetic variation in genes encoding cytokines and their receptors, determine the intensity of the inflammatory response, which may contribute to individual differences in severity of outcome of the disease. Tumor necrosis factor alpha (TNF-α) is a potent pro-inflammatory cytokine and acid inhibitor. A bi allelic G to A polymorphism at -308 upstream from the transcription initiation site of the promoter is associated with elevated TNF levels. The present study is aimed at evaluating the role of TNF-α-308 (G → A) gene polymorphism and susceptibility to GC.

SUBJECTS AND METHODS

A case-control study was carried out in 114 GC patients and 229 healthy control subjects. TNF-α genotyping at position-308 (G → A) was carried out by amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) method followed by agarose gel electrophoresis.

RESULTS

The distribution of TNF-α genotypes at -308 (G → A) were GG 28.07%, GA 66.67% and AA 5.26% in GC patients and GG 33.19%, GA 55.89% and AA 10.92% in control subjects. The frequencies of alleles G and A were 0.614 and 0.386 in GC patients and 0.611 and 0.389 in control subjects respectively.

CONCLUSION

The study showed no significant difference in the distribution of genotype and allelic frequencies between GC patients and control subject.

Development of a simplified diagnostic indicators scoring system and validation for peptic ulcer perforation in a developing country

Objective:

To perform and confirm a simplified diagnostic indicators scoring system for predicting peptic ulcer perforation (PUP).

Methods:

A case–control study was conducted including 812 consecutive patients with PUP from retrospective medical records. Each diagnostic indicator measurable at the time of admittance was analyzed by a multiple regression. Stepwise logistic regression was applied with backward elimination of statistically significant predictors from the full model, with P ≥ 0.05 for exclusion. The item scores were transformed from regression coefficients and computed to a total score. The risk of PUP was interpreted using total scores as a simple predictor. This system was internally validated in 218 consecutive patients and compared to existing systems.

Results:

A PUP risk score was determined from the diagnostic indicators associated with PUP: gender, age, nonsteroidal antiinflammatory drugs used, history of peptic ulcer, intense abdominal pain, guarding, X-ray free air positive, and referral from other hospitals. Item scores ranged from 0–6.0 and the total score ranged from 0–34.0. The area under the receiver operating characteristic curve shows that there was 91.73% accuracy in the total scores predicting the likelihood of PUP. The likelihood of PUP among low risk (scores <10.5), moderate risk (scores 11–21), and high risk (scores ≥ 21.5) patients was 0.13, 11.44, and 1.95, respectively.

Conclusion:

This scoring system is an effective diagnostic indicator for identifying the complex cases of PUP. It is a simple system and can help guide clinicians, providing them with a more efficient way to accurately subgroup patients while also reducing potential biases.

Prevalence of Helicobacter pylori infection measured with urinary antibody in an urban area of Japan, 2008-2010

Helicobacter pylori (H. pylori) has expanded to infect about half the world's population. Although there were many studies on the prevalence of H. pylori infection for defined areas in the 1990s throughout the world, there were only limited sources tracking its latest prevalence among large populations. In the present study, we estimated the prevalence of H. pylori among the inhabitants of Nagoya, an urban area of Japan. Study subjects were 5167 participants (1467 males and 3700 females) aged 35 to 69 years from the Daiko Study, a part of the Japan Multi-Institutional Collaborative Cohort Study (J-MICC Study). A urinary anti-H. pylori antibody was used to detect H. pylori infection. The history of eradication treatments for H. pylori infection was obtained using self-administered questionnaires. The prevalence detected by the urinary test included 19.6% (95% confidence interval; 16.8-22.6%) for those aged 35-39 years, 25.8% (23.5-28.2%) for 40-49 years, 39.4% (36.8-42.1%) for 50-59 years, 50.3% (47.8-52.7%) for 60-69 years, and 36.4% (35.1-37.7%). Among 5167 participants, 266 (5.1%) stated that they had received an eradication treatment. Since 167 subjects with negative urinary tests replied that they had been seropositive for H. pylori in the past, they were included among the ever-infected inhabitant group. Consequently, the overall rate of those with a history of persistent infection was 39.6% (38.3-40.9%). The prevalence of H. pylori infection observed in Nagoya seemed to be lower than the corresponding prevalence reported in other studies of Japan. That lower rate might be due to the reduced exposure from improved urban sanitary conditions.

Rationale in diagnosis and screening of atrophic gastritis with stomach-specific plasma biomarkers

BACKGROUND AND AIMS

Atrophic gastritis (AG) results most often from Helicobacter pylori (H. pylori) infection. AG is the most important single risk condition for gastric cancer that often leads to an acid-free or hypochlorhydric stomach. In the present paper, we suggest a rationale for noninvasive screening of AG with stomach-specific biomarkers.

METHODS

The paper summarizes a set of data on application of the biomarkers and describes how the test results could be interpreted in practice.

RESULTS

In AG of the gastric corpus and fundus, the plasma levels of pepsinogen I and/or the pepsinogen I/pepsinogen II ratio are always low. The fasting level of gastrin-17 is high in AG limited to the corpus and fundus, but low or non-elevated if the AG occurs in both antrum and corpus. A low fasting level of G-17 is a sign of antral AG or indicates high intragastric acidity. Differentiation between antral AG and high intragastric acidity can be done by assaying the plasma G-17 before and after protein stimulation, or before and after administration of the proton pump inhibitors (PPI). Amidated G-17 will rise if the antral mucosa is normal in structure. H. pylori antibodies are a reliable indicator of helicobacter infection, even in patients with AG and hypochlorhydria.

CONCLUSIONS

Stomach-specific biomarkers provide information about the stomach health and about the function of stomach mucosa and are a noninvasive tool for diagnosis and screening of AG and acid-free stomach.