Biomarkers of Helicobacter pylori-associated gastric cancer

A pattern-recognition-based clustering method for non-invasive diagnosis and classification of various gastric conditions

Conventional endoscopic biopsy tests are not suitable for early detection of the acute onset and progression of peptic ulcer as well as various gastric complications. This also limits its suitability for widespread population-based screening and consequently, many people with complex gastric phenotypes remain undiagnosed. Here, we demonstrate a new non-invasive methodology for accurate diagnosis and classification of various gastric disorders exploiting a pattern-recognition-based cluster analysis of a breathomics dataset generated from a simple residual gas analyzer-mass spectrometry. The clustering approach recognizes unique breathograms and "breathprints" signatures that clearly reflect the specific gastric condition of an individual person. The method can selectively distinguish the breath of peptic ulcer and other gastric dysfunctions like dyspepsia, gastritis, and gastroesophageal reflux disease patients from the exhaled breath of healthy individuals with high diagnostic sensitivity and specificity. Moreover, the clustering method exhibited a reasonable power to selectively classify the early-stage and high-risk gastric conditions with/without ulceration, thus opening a new non-invasive analytical avenue for early detection, follow-up, and fast population-based robust screening strategy of gastric complications in the real-world clinical domain.

Genetic and epigenetic instability induced by betel quid associated chemicals

Over the years, betel quid chewing and tobacco use have attracted considerable interest as they are implicated as the most likely causative risk factors of oral and esophageal cancers. Although areca nut use and betel quid chewing may lead to apoptosis, chronic exposure to areca nut and slaked lime may promote pre-malignant and malignant transformation of oral cells. The putative mutagenic and carcinogenic mechanisms may involve endogenous nitrosation of areca and tobacco alkaloids as well as the presence of direct alkylating agents in betel quid and smokeless tobacco. Metabolic activation of carcinogenic N-nitrosamines by phase-I enzymes is required not only to elicit the genotoxicity via the reactive intermediates but also to potentiate the mutagenicity with the sporadic alkylations of nucleotide bases, resulting in the formation of diverse DNA adducts. Persistent DNA adducts provides the impetus for genetic and epigenetic lesions. The genetic and epigenetic factors cumulatively influence the development and progression of disorders such as cancer. Accumulation of numerous genetic and epigenetic aberrations due to long-term betel quid (with or without tobacco) chewing and tobacco use culminates into the development of head and neck cancers. We review recent evidence that supports putative mechanisms for mutagenicity and carcinogenicity of betel quid chewing along with tobacco (smoking and smokeless) use. The detailed molecular mechanisms of the extent of accumulation and patterns of genetic alterations, indicative of the prior exposure to carcinogens and alkylating agents because of BQ chewing and tobacco use, have not yet been elucidated.

Epigenetic regulation of autophagy by non-coding RNAs in gastrointestinal tumors: Biological functions and therapeutic perspectives

Cancer is the manifestation of changes and mutations in genetic and epigenetic levels. Non-coding RNAs (ncRNAs) are commonly dysregulated in disease pathogenesis, and their role in cancer has been well-documented. The ncRNAs regulate various molecular pathways and mechanisms in cancer that can lead to induction/inhibition of carcinogenesis. Autophagy is a molecular "self-digestion" mechanism its function can be pro-survival or pro-death in tumor cells. The aim of the present review is to evaluate the role of ncRNAs in regulating autophagy in gastrointestinal tumors. The role of the ncRNA/autophagy axis in affecting the progression of gastric, liver, colorectal, pancreatic, esophageal, and gallbladder cancers is investigated. Both ncRNAs and autophagy mechanisms can function as oncogenic or onco-suppressor and this interaction can determine the growth, invasion, and therapy response of gastrointestinal tumors. ncRNA/autophagy axis can reduce/increase the proliferation of gastrointestinal tumors via the glycolysis mechanism. Furthermore, related molecular pathways of metastasis, such as EMT and MMPs, are affected by the ncRNA/autophagy axis. The response of gastrointestinal tumors to chemotherapy and radiotherapy can be suppressed by pro-survival autophagy, and ncRNAs are essential regulators of this mechanism. miRNAs can regulate related genes and proteins of autophagy, such as ATGs and Beclin-1. Furthermore, lncRNAs and circRNAs down-regulate miRNA expression via sponging to modulate the autophagy mechanism. Moreover, anti-cancer agents can affect the expression level of ncRNAs regulating autophagy in gastrointestinal tumors. Therefore, translating these findings into clinics can improve the prognosis of patients.

High expression of GNB4 predicts poor prognosis in patients with Helicobacter pylori-positive advanced gastric cancer

Background

Helicobacter pylori (H. pylori) is recognized as the most evident etiologic factor of infection-related gastric cancer (GC) and its involvement in GC initiation and progression has been well investigated. However, only a limited number of studies were performed to identify prognostic biomarkers and evaluate their clinical significance in GC patients infected with H. pylori. This study was conducted to investigate the clinical significance as well as its potential prognostic value of GNB4 in H. pylori-positive GC patients receiving standard treatment.

Methods

Retrospective statistical analysis was performed on 448 H. pylori-positive GC patients, with 137 early gastric cancer (EGC) patients undergoing radical gastrectomy alone and 311 advanced gastric cancer (AGC) patients receiving the same surgical procedure followed by fluorouracil-based chemotherapy. GNB4 expression was detected by immunohistochemistry staining on patient samples. H. pylori infection was routinely examined on endoscopic biopsy and/or surgical specimen of GC patients.

Results

High expression of GNB4 was 65.7% (90/137) in EGC and 62.7% (195/311) in AGC patients infected with H. pylori, respectively. In EGC patients, GNB4 expression was not associated with either clinicopathological parameters or 5-year overall survival (OS). In AGC patients however, high expression of GNB4 was significantly associated with patient’s pathological stage (P=0.047). Univariate analysis showed that tumor invasion depth (P=0.001), lymph node metastasis (P<0.001), pathological stage (P<0.001) as well as high expression of GNB4 (P=0.002) were significantly associated with 5-year OS. Multivariate analysis further identified lymph node metastasis (P=0.013) and GNB4 high expression (P=0.020) as independent prognostic factors for long-term outcome of H. pylori-positive AGC patients.

Conclusions

This study demonstrates that high expression of GNB4 is significantly associated with pathological stage of AGC patients with H. pylori infection. GNB4 expression independently predicts the 5-year OS of H. pylori-positive AGC patients undergoing radical gastrectomy and adjuvant chemotherapy.

BCAP31 drives TNBC development by modulating ligand-independent EGFR trafficking and spontaneous EGFR phosphorylation

Identification of novel targets for triple-negative breast cancer (TNBC) is an urgent task as targeted therapies have increased the lifespans of Oestrogen Receptor +/ Progesterone Receptor + and HER2+ cancer patients. Methods: genes involved in protein processing in the endoplasmic reticulum, which have been reported to be key players in cancer, were used in loss-of-function screening to evaluate the oncogenic roles of these genes to identify candidate target genes in TNBC. In vitro and in vivo function assays as well as clinical prognostic analysis were used to study the oncogenic role of the gene. Molecular and cell based assays were further employed to investigate the mechanisms. Results: B Cell Receptor Associated Protein 31 (BCAP31), the expression of which is correlated with early recurrence and poor survival among patients, was identified an oncogene in our assay. In vitro studies further suggested that BCAP31 acts as a key oncogene by promoting TNBC development. We also showed that BCAP31 interacts with epidermal growth factor receptor (EGFR) and serves as an inhibitor of ligand-independent EGFR recycling, sustaining EGFR autophosphorylation and activation of downstream signalling. Conclusion: These findings reveal the functional role of BCAP31, an ER-related protein, in EGFR dysregulation and TNBC development.

Up-Regulation of miR-21, miR-25, miR-93, and miR-106b in Gastric Cancer

BACKGROUND

Differential expression profile of microRNAs (miRNAs) could be a diagnosis signature for monitoring gastric cancer (GC) progression. In this study, we focus on the comparison of expression levels of miR-21, miR-25, miR-93, miR-106b, and miR-375 during the sequential pattern of GC development, including normal gastric, gastric dysplasia, and GC sample.

METHODS

We used SYBR Green-based quantitative-PCR to quantify miRNAs expression.

RESULTS

Our analysis revealed the increased expression levels of miR-21 (p = 0.034), miR-25 (p = 0.0003), miR-93 (p = 0.0406), and miR-106b (p = 0.023) in GC samples. In addition, GC patients with positive lymph node metastasis showed the up-regulation of miR-25, miR-93, and miR-106b (p < 0.05).

CONCLUSION

Our findings suggested that the expression of miR-21, miR-25, miR-93, and miR-106b altered in GC, and some of them may be further investigated as biomarkers for GC early detection and prognosis prediction.

Up-Regulation of miR-21, miR-25, miR-93, and miR-106b in Gastric Cancer

Background:

Differential expression profile of microRNAs (miRNAs) could be a diagnosis signature for monitoring gastric cancer (GC) progression. In this study, we focus on the comparison of expression levels of miR-21, miR-25, miR-93, miR-106b, and miR-375 during the sequential pattern of GC development, including normal gastric, gastric dysplasia, and GC sample.

Methods:

We used SYBR Green-based quantitative-PCR to quantify miRNAs expression.

Results:

Our analysis revealed the increased expression levels of miR-21 (p = 0.034), miR-25 (p = 0.0003), miR-93 (p = 0.0406), and miR-106b (p = 0.023) in GC samples. In addition, GC patients with positive lymph node metastasis showed the up-regulation of miR-25, miR-93, and miR-106b (p < 0.05).

Conclusion:

Our findings suggested that the expression of miR-21, miR-25, miR-93, and miR-106b altered in GC, and some of them may be further investigated as biomarkers for GC early detection and prognosis prediction.

Evaluation of altered expression of miR-9 and miR-106a as an early diagnostic approach in gastric cancer

Background

The role of microRNAs (miRNAs) in cellular processes such as growth, apoptosis, differentiation and proliferation verifies the importance of miRNAs in carcinogenesis. Moreover, levels of miRNAs are dysregulated in cancer cells, so they could be used as novel classes of biomarkers for diagnosing cancer. The oncogenic role of miR-106a and its increased expression have been demonstrated in some cancers. In contrast, there is no consensus for miR-9 expression rate in different cancers. Therefore, this study was done to investigate the role of miR-106a and miR-9 in gastric cancer (GC).

Methods

The current study was performed on 31 GC tissues as case, and 31 healthy adjacent tissues as a control group. Quantitative reverse transcriptase (q-RT) PCR was used for studying the expression rate of both miR-106a and miR-9.

Results

The expression rate of both miRNAs in cancerous tissues was significantly higher than healthy adjacent tissues (≈10 folds) (P<0.05).

Conclusions

The results showed that the expression rate of both markers was significantly increased in cancerous tissues. Therefore, they can be suggested as potential biomarkers for cancer diagnosis and prognosis as well as targets for therapy.

Host pathogen interactions in Helicobacter pylori related gastric cancer

Helicobacter pylori (H. pylori), discovered in 1982, is a microaerophilic, spiral-shaped gram-negative bacterium that is able to colonize the human stomach. Nearly half of the world's population is infected by this pathogen. Its ability to induce gastritis, peptic ulcers, gastric cancer and mucosa-associated lymphoid tissue lymphoma has been confirmed. The susceptibility of an individual to these clinical outcomes is multifactorial and depends on H. pylori virulence, environmental factors, the genetic susceptibility of the host and the reactivity of the host immune system. Despite the host immune response, H. pylori infection can be difficult to eradicate. H. pylori is categorized as a group I carcinogen since this bacterium is responsible for the highest rate of cancer-related deaths worldwide. Early detection of cancer can be lifesaving. The 5-year survival rate for gastric cancer patients diagnosed in the early stages is nearly 90%. Gastric cancer is asymptomatic in the early stages but always progresses over time and begins to cause symptoms when untreated. In 97% of stomach cancer cases, cancer cells metastasize to other organs. H. pylori infection is responsible for nearly 60% of the intestinal-type gastric cancer cases but also influences the development of diffuse gastric cancer. The host genetic susceptibility depends on polymorphisms of genes involved in H. pylori-related inflammation and the cytokine response of gastric epithelial and immune cells. H. pylori strains differ in their ability to induce a deleterious inflammatory response. H. pylori-driven cytokines accelerate the inflammatory response and promote malignancy. Chronic H. pylori infection induces genetic instability in gastric epithelial cells and affects the DNA damage repair systems. Therefore, H. pylori infection should always be considered a pro-cancerous factor.

Julian Davies and the discovery of kanamycin resistance transposon Tn5

This paper recounts some of my fond memories of a collaboration between Julian Davies and myself that started in 1974 in Geneva and that led to our serendipitous discovery of the bacterial kanamycin resistance transposon Tn5, and aspects of the lasting positive impact of our interaction and discovery on me and the community. Tn5 was one of the first antibiotic resistance transposons to be found. Its analysis over the ensuing decades provided valuable insights into mechanisms and control of transposition, and led to its use as a much-valued tool in diverse areas of molecular genetics, as also will be discussed here.

Correlation of Helicobacter pylori and interleukin-8 mRNA expression in high risk gastric cancer population prediction

AIM: To evaluate (1) the association of the Helicobacter pylori (H. pylori) test and interleukin-8 (IL-8) mRNA expression alone and the severity of gastric cancer (GC); (2) the association of both tests were added to patients' characteristics to identifli Thai suspected patients of gastric cancer who would receive the most benefit; and (3) diagnostic value of levels of IL-8 mRNA expression for gastric cancer.

METHODS: A cross-sectional analytical study was completed with 220 patients with 86 GC patients who underwent endoscopy with gastric surgery divided into non-metastasis and metastasis groups, and 134 patients with benign lesions who underwent endoscopic examination, at the Gastrointestinal Surgery and Endoscopy Unit, Chiang Mai University Hospital between 2006 and 2010. Of 220 patients, 86 cases of diagnosed gastric adenocarcinoma were in an advanced stage and 134 cases were non-cancer patients.

RESULTS: The IL-8 mRNA expression showed predominant association with advanced GC when compared to H. pylori infection alone [OR (95%CI); 0.86 (0.49-1.53) vs 5.44 (3.08-9.62)] when including the patients’ characteristics the highest of the area under the receiver operating characteristic curves (AuROC) of the model were males older than 40 years of age [AuROC (95%CI); 0.81 (0.75-0.86)]. However, preliminary testing for diagnostic indices of four cut-off points of IL-8 mRNA expression to predict the severity of GC cases found an increasing suboptimal trend from the likelihood ratio of positive to differentiate the severity in the GC group. The IL-8 mRNA expression showed a predominant association with GC when compared to H. pylori infection, especially in males older than 40 years of age who may benefit most from this test.

CONCLUSION: The future research of IL-8 mRNA expression to predict severity in the gastric cancer group should be warranted.

Progress and remaining challenges for cancer control in Latin America and the Caribbean

Cancer is one of the leading causes of mortality worldwide, and an increasing threat in low-income and middle-income countries. Our findings in the 2013 Commission in The Lancet Oncology showed several discrepancies between the cancer landscape in Latin America and more developed countries. We reported that funding for health care was a small percentage of national gross domestic product and the percentage of health-care funds diverted to cancer care was even lower. Funds, insurance coverage, doctors, health-care workers, resources, and equipment were also very inequitably distributed between and within countries. We reported that a scarcity of cancer registries hampered the design of credible cancer plans, including initiatives for primary prevention. When we were commissioned by The Lancet Oncology to write an update to our report, we were sceptical that we would uncover much change. To our surprise and gratification much progress has been made in this short time. We are pleased to highlight structural reforms in health-care systems, new programmes for disenfranchised populations, expansion of cancer registries and cancer plans, and implementation of policies to improve primary cancer prevention.

MiR-181a suppresses autophagy and sensitizes gastric cancer cells to cisplatin

A number of chemotherapy drugs can induce autophagy. This inducible autophagy is a pro-survival mechanism and contributes to the development of acquired drug resistance. Emerging evidence indicates that miRNA regulates autophagy via targeting autophagy related genes and is involved in drug resistance. We previously demonstrated that miR-181a plays an important role in gastric cancer. The present study aimed to explore the effect of miR-181a on autophagy regulation and cisplatin resistance. We revealed that miR-181a is a novel negative regulator of autophagy in cisplatin-resistant cells SGC7901/CDDP. Then we indicated that ATG5 was a potential target of miR-181a. Furthermore, overexpression of miR-181a significantly enhanced the sensitivity of SGC7901/CDDP cells to cisplatin in vitro and reduced the volumes of gastric tumor xenografts in nude mice. Our finding provides evidence that miR-181a functions as a primary autophagy-related modulator and reverses cisplatin-resistance in GC cells.

Dietary amelioration of Helicobacter infection

We review herein the basis for using dietary components to treat and/or prevent Helicobacter pylori infection, with emphasis on (a) work reported in the last decade, (b) dietary components for which there is mechanism-based plausibility, and (c) components for which clinical results on H pylori amelioration are available. There is evidence that a diet-based treatment may reduce the levels and/or the virulence of H pylori colonization without completely eradicating the organism in treated individuals. This concept was endorsed a decade ago by the participants in a small international consensus conference held in Honolulu, Hawaii, USA, and interest in such a diet-based approach has increased dramatically since then. This approach is attractive in terms of cost, treatment, tolerability, and cultural acceptability. This review, therefore, highlights specific foods, food components, and food products, grouped as follows: bee products (eg, honey and propolis); probiotics; dairy products; vegetables; fruits; oils; essential oils; and herbs, spices, and other plants. A discussion of the small number of clinical studies that are available is supplemented by supportive in vitro and animal studies. This very large body of in vitro and preclinical evidence must now be followed up with rationally designed, unambiguous human trials.

Implementation of gastric cancer screening - the global experience

Gastric cancer (GC) is still an important global healthcare problem, and in absolute figures it is going to remain at the present level in foreseeable future. In general, survival of patients with GC is poor mainly due to advanced-stage diagnosis. Early-stage GC can be cured by endoscopic resection or less invasive surgical treatment. Unfortunately, there is no appropriate screening strategy available for global application. This article provides a description of established national and regional GC screening programs and the screening modalities used. This review also summarizes current approaches to develop cancer-screening biomarkers. Although candidates with initial promising results have been suggested, moving discovery into clinical practice is still a major challenge. Well-designed biomarker studies, with systematic validation steps, are needed to decrease the burden of this fatal disease.

Circulating mitochondrial DNA level, a noninvasive biomarker for the early detection of gastric cancer

BACKGROUND

Gastric cancer represents a major health burden worldwide and is often diagnosed at an advanced stage. Biomarkers for screening and prevention of gastric cancer are missing. Changes in peripheral blood mitochondrial DNA (mtDNA) have emerged as a potential preventive/diagnosis biomarker for cancer risk. We aimed to determine whether peripheral leukocytes mtDNA levels are associated with stages of the gastric carcinogenesis cascade.

METHODS

We measured mtDNA by quantitative real-time PCR assay in peripheral leukocytes of 28 patients with non-atrophic gastritis (NAG), 74 patients with gastric cancer, and 48 matched asymptomatic controls. In parallel, the serologic level of IL8 was determined.

RESULTS

Mean mtDNA level was higher in patients with gastric cancer (P = 0.0095) than in controls, with values >8.46 significantly associated with gastric cancer (OR, 3.93). Three ranges of mtDNA values were identified: interval I, <2.0; interval II, 2.0-20; and interval III, >20. Interval I included mainly NAG cases, and few gastric cancer samples and interval III corresponded almost exclusively to patients with gastric cancer. All controls fell in interval II, together with some NAG and gastric cancer cases. IL8 levels were significantly higher in patients with gastric cancer (P < 0.05), with levels >50 pg/mL observed exclusively in patients with gastric cancer, allowing to distinguish them within interval II. We validated mtDNA results in a second cohort of patients, confirming that mtDNA was significantly higher in gastric cancer than in patients with preneoplasia.

CONCLUSIONS

Circulating levels of mtDNA and IL8 constitute a potential biomarker for the early detection of gastric cancer.

IMPACT

Our findings lead us to propose a new noninvasive method to detect patients with gastric cancer risk.

The gastric microbial community, Helicobacter pylori colonization, and disease

Long thought to be a sterile habitat, the stomach contains a diverse and unique community of bacteria. One particular inhabitant, Helicobacter pylori, colonizes half of the world's human population and establishes a decades-long infection that can be asymptomatic, pathogenic, or even beneficial for the host. Many host and bacterial factors are known to influence an individual's risk of gastric disease, but another potentially important determinant has recently come to light: the host microbiota. Although it is unclear to what extent H. pylori infection perturbs the established gastric microbial community, and H. pylori colonization seems generally resistant to disturbances in the host microbiota, it can modulate H. pylori pathogenicity. Interactions between H. pylori and bacteria at non-gastric sites are likely indirect--via programming of the pro-inflammatory vs. regulatory T lymphocytes--which may have a significant impact on human health.

Intestinal microbiome and digoxin inactivation: meal plan for digoxin users?

There is an increasing interest in the role of intestinal microbiome in human diseases and therapeutic agents' bioavailability, activity and toxicity. Epidemiological data show that the bioavailability of digoxin, a widely used agent for heart disease, varies among individuals. The inactivation of digoxin was found when it was incubated with gut bacterium Eggerthella lenta in vitro decades ago. However, the underlying mechanisms of digoxin inactivation are still unclear. A recent study using animal models uncovered this mystery, which suggested that arginine supplements might be a potential intervention in increasing digoxin activity by inhibiting the expression of cardiac glycoside reductase gene operons that inactivated digoxin. This perspective summarizes the connections among the intestinal microbiome, the digoxin inactivation, the metabolism of arginine. We also discuss several issues yet to be addressed in the future, making better strategies in the application of dietary arginine supplements for digoxin users.