Helicobacter pylori infection recruits bone marrow-derived cells that participate in gastric preneoplasia in mice

Biombalance™, an Oligomeric Procyanidins-Enriched Grape Seed Extract, Prevents Inflammation and Microbiota Dysbiosis in a Mice Colitis Model

Inflammatory bowel disease (IBD) results from genetic factors, environmental factors, and intestinal microbiota interactions. This study investigated the effects of Biombalance™ (BB) in dextran sulphate sodium (DSS)-induced colitis in mice. BB extract exhibits high antioxidant activity, as determined by DPPH and ORAC tests. Mice were fed a standard diet, and BB was administered by gavage for ten days, before administration of 2.75% DSS in drinking water. BB significantly protected mice against DSS effects, as assessed by colon length, disease activity index (DAI) scores and colonic pathological damage. In addition, BB inhibited the expression of proinflammatory markers, such as IL-6, IL-17, CXCL1 and TNF-α, and the inflammatory mediators iNOS, TGF-β, FoxP3 and F4/80, while increasing IL-10 expression in the colon. BB modified microbiota composition, attenuating the microbial diversity lost due to DSS, increasing beneficial bacteria like Muribaculum, Lactobacillus, Muscispirillum, Roseburia and Bifidobacterium, and decreasing potentially harmful bacteria such as Proteobacteria and Enterococcus. Interestingly, microbiota-predicted functions using PICRUSt revealed that BB extract increases the antioxidant superpathway of ubiquinol biosynthesis, including ubiquinol-7, 8, 9 and 10 (CoenzymesQ). These findings suggest that Biombalance™ administration may help to reduce gut inflammation and oxidation, at least partly through modifications of the microbiota and its metabolites.

Chronic Infection With Gastric Helicobacters Induces Hepatic Lesions in Mice

BACKGROUND

Helicobacter pylori infection is one of the most prevalent chronic bacterial infections worldwide. This bacillus colonizes the human stomach lifelong, where it induces chronic gastritis, evolving in some cases to gastro-duodenal ulcers, gastric adenocarcinoma, and mucosa-associated lymphoid tissue lymphoma. H. pylori infection has also been associated with extragastric diseases, and clinical data have suggested a role in liver pathogenesis. This retrospective study evaluated the consequences of chronic infection with gastric Helicobacters on liver pathogenesis in a mouse experimental model.

MATERIALS AND METHODS

C57BL6 mice were infected with either H. felis (n = 12) or five human and mouse-adapted strains of H. pylori (n = 77) for one year. Uninfected mice were used as negative controls (n = 10). Histopathological analysis of paraffin-embedded liver tissue sections was performed, and scores were determined in a double-blind manner for inflammation and steatosis.

RESULTS

Mice infected with H. felis and several H. pylori strains developed more liver parenchymal inflammation and steatosis, known precursor lesions of liver carcinogenesis, compared to non-infected mice. The presence of liver lesions was positively correlated with the detection of lesions of the gastric mucosa, more particularly gastric inflammation and metaplasia.

CONCLUSION

Chronic infection of mice with H. felis and H. pylori induces liver pathogenesis characterized by parenchymal inflammation and steatosis, which may be associated with the severity of gastric histopathological lesions. Understanding H. pylori infection's impact on extragastric lesions could in fine help detect and prevent the emergence of other digestive tract-related diseases.

Helicobacter pylori CagA protein induces gastric cancer stem cell-like properties through the Akt/FOXO3a axis

The presence of Helicobacter pylori (H. pylori) infection poses a substantial risk for the development of gastric adenocarcinoma. The primary mechanism through which H. pylori exerts its bacterial virulence is the cytotoxin CagA. This cytotoxin has the potential to induce inter-epithelial mesenchymal transition, proliferation, metastasis, and the acquisition of stem cell-like properties in gastric cancer (GC) cells infected with CagA-positive H. pylori. Cancer stem cells (CSCs) represent a distinct population of cells capable of self-renewal and generating heterogeneous tumor cells. Despite evidence showing that CagA can induce CSCs-like characteristics in GC cells, the precise mechanism through which CagA triggers the development of GC stem cells (GCSCs) remains uncertain. This study reveals that CagA-positive GC cells infected with H. pylori exhibit CSCs-like properties, such as heightened expression of CD44, a specific surface marker for CSCs, and increased ability to form tumor spheroids. Furthermore, we have observed that H. pylori activates the PI3K/Akt signaling pathway in a CagA-dependent manner, and our findings suggest that this activation is associated with the CSCs-like characteristics induced by H. pylori. The cytotoxin CagA, which is released during H. pylori infection, triggers the activation of the PI3K/Akt signaling pathway in a CagA-dependent manner. Additionally, CagA inhibits the transcription of FOXO3a and relocates it from the nucleus to the cytoplasm by activating the PI3K/Akt pathway. Furthermore, the regulatory function of the Akt/FOXO3a axis in the transformation of GC cells into a stemness state was successfully demonstrated.

Helicobacter pylori-activated fibroblasts as a silent partner in gastric cancer development

The discovery of Helicobacter pylori (Hp) infection of gastric mucosa leading to active chronic gastritis, gastroduodenal ulcers, and MALT lymphoma laid the groundwork for understanding of the general relationship between chronic infection, inflammation, and cancer. Nevertheless, this sequence of events is still far from full understanding with new players and mediators being constantly identified. Originally, the Hp virulence factors affecting mainly gastric epithelium were proposed to contribute considerably to gastric inflammation, ulceration, and cancer. Furthermore, it has been shown that Hp possesses the ability to penetrate the mucus layer and directly interact with stroma components including fibroblasts and myofibroblasts. These cells, which are the source of biophysical and biochemical signals providing the proper balance between cell proliferation and differentiation within gastric epithelial stem cell compartment, when exposed to Hp, can convert into cancer-associated fibroblast (CAF) phenotype. The crosstalk between fibroblasts and myofibroblasts with gastric epithelial cells including stem/progenitor cell niche involves several pathways mediated by non-coding RNAs, Wnt, BMP, TGF-β, and Notch signaling ligands. The current review concentrates on the consequences of Hp-induced increase in gastric fibroblast and myofibroblast number, and their activation towards CAFs with the emphasis to the altered communication between mesenchymal and epithelial cell compartment, which may lead to inflammation, epithelial stem cell overproliferation, disturbed differentiation, and gradual gastric cancer development. Thus, Hp-activated fibroblasts may constitute the target for anti-cancer treatment and, importantly, for the pharmacotherapies diminishing their activation particularly at the early stages of Hp infection.

A comprehensive evaluation of an animal model for Helicobacter pylori-associated stomach cancer: Fact and controversy

Even though Helicobacter pylori infection was the most causative factor of gastric cancer, numerous in vivo studies failed to induce gastric cancer using H. pylori infection only. The utilization of established animal studies in cancer research is crucial as they aim to investigate the coincidental association between suspected oncogenes and pathogenesis as well as generate models for the development and testing of potential treatments. The methods to establish gastric cancer using infected animal models remain limited, diverse in methods, and showed different results. This study investigates the differences in animal models, which highlight different pathological results in gaster by literature research. Electronic databases searched were performed in PubMed, Science Direct, and Cochrane, without a period filter. A total of 135 articles were used in this study after a full-text assessment was conducted. The most frequent animal models used for gastric cancer were Mice, while Mongolian gerbils and Transgenic mice were the most susceptible model for gastric cancer associated with H. pylori infection. Additionally, transgenic mice showed that the susceptibility to gastric cancer progression was due to genetic and epigenetic factors. These studies showed that in Mongolian gerbil models, H. pylori could function as a single agent to trigger stomach cancer. However, most gastric cancer susceptibilities were not solely relying on H. pylori infection, and numerous factors are involved in cancer progression. Further study using Mongolian gerbils and Transgenic mice is crucial to conduct and establish the best models for gastric cancer associated H. pylori.

Integrated analysis of Helicobacter pylori-related prognostic gene modification patterns in the tumour microenvironment of gastric cancer

BACKGROUND

Helicobacter pylori (HP) infection is one of the leading causes of gastric cancer (GC). However, the interaction between HP and the TME, and its carcinogenic mechanism remains unknown.

METHODS

The HP-related prognostic genes were identified based on HP infection-related gene markers and HP infection sample datasets by risk method and NMF algorithm. Principal component analysis (PCA) algorithm was used to constructed the HPscore system. The "limma" R package was employed to determine differentially expressed genes. In addition, the R packages, such as "xCell" and "GSVA", was used to analyze the relationship between the HPscore and tumor microenvironment. Finally, quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to verify the expression levels of 28 HP-related prognostic genes in tissues.

RESULTS

We successfully identified 28 HP-related prognostic genes that accurately classified the GC population. There are significant differences in survival between different subgroups (high-, low-risk and cluster_1,2). Thereafter, the HPscore system was constructed to evaluate the signatures of the 28 HP-related prognostic genes. The overall survival rate in the high-HPscore group was poor and immunological surveillance was reduced, whereas the low-HPscore group had a survival advantage and was related to the inflammatory response. HPscore was also strongly correlated with the tumour stage, TME cell infiltration and stemness. The qRT-PCR results showed that DOCK4 expression level of 28 HP-related prognostic genes was higher in gastric cancer tissues than in adjacent tissues.

CONCLUSIONS

HP signatures play a crucial role in the TME and tumourigenesis. HPscore evaluation of a single tumour sample can help identify the TME characteristics and the carcinogenic mechanism of GC patients infected with HP, based on which personalized treatment can be administered.

The origin of gastric cancer stem cells and their effects on gastric cancer: Novel therapeutic targets for gastric cancer

Gastric cancer (GC) is one of the most prevalent malignancies and the most common causes of cancer-related mortality worldwide. Furthermore, the prognosis of advanced GC remains poor even after surgery combined with chemoradiotherapy. As a small group of cells with unlimited differentiation and self-renewal ability in GC, accumulating evidence shows that GC stem cells (GCSCs) are closely associated with the refractory characteristics of GC, such as drug resistance, recurrence, and metastasis. With the extensive development of research on GCSCs, GCSCs seem to be promising therapeutic targets for GC. However, the relationship between GCSCs and GC is profound and intricate, and its mechanism of action is still under exploration. In this review, we elaborate on the source and key concepts of GCSCs, systematically summarize the role of GCSCs in GC and their underlying mechanisms. Finally, we review the latest information available on the treatment of GC by targeting GCSCs. Thus, this article may provide a theoretical basis for the future development of the novel targets based on GCSCs for the treatment of GC.

Effects of helicobacter pylori on tumor microenvironment and immunotherapy responses

Helicobacter pylori is closely associated with gastric cancer. During persistent infection, Helicobacter pylori can form a microenvironment in gastric mucosa which facilitates the survival and colony formation of Helicobacter pylori. Tumor stromal cells are involved in this process, including tumor-associated macrophages, mesenchymal stem cells, cancer-associated fibroblasts, and myeloid-derived suppressor cells, and so on. The immune checkpoints are also regulated by Helicobacter pylori infection. Helicobacter pylori virulence factors can also act as immunogens or adjuvants to elicit or enhance immune responses, indicating their potential applications in vaccine development and tumor immunotherapy. This review highlights the effects of Helicobacter pylori on the immune microenvironment and its potential roles in tumor immunotherapy responses.

Evidence of Stem Cells Mobilization in the Blood of Patients with Pancreatitis: A Potential Link with Disease Severity

A growing number of studies indicate the potential involvement of various populations of bone marrow-derived stem cells (BMSCs) in tissue repair. However, the mobilization of BMSCs to the peripheral blood (PB) in acute and chronic pancreatitis (AP and CP) has not been investigated. A total of 78 patients were assigned into AP, CP, and healthy control groups in this study. Using flow cytometry, we found that VSELs, EPCs, and CD133+SCs were mobilized to the PB of patients with both AP and CP. Interestingly, AP and CP patients exhibited lower absolute number of circulating MSCs in the PB compared to healthy individuals. SC mobilization to the PB was more evident in patients with AP than CP and in patients with moderate/severe AP than mild AP. Using ELISA, we found a significantly increased HGF concentration in the PB of patients with AP and SDF1α in the PB of patients with CP. We noted a significant positive correlation between SDF1α concentration and the mobilized population of CD133+SCs in AP and between C5a and the mobilized population of VSELs moderate/severe AP. Thus, bone marrow-derived SCs may play a role in the regeneration of pancreatic tissue in both AP and CP, and mobilization of VSELs to the PB depends on the severity of AP.

Impact of Cancer Stem Cells on Therapy Resistance in Gastric Cancer

Gastric cancer (GC) is the fourth leading cause of cancer death worldwide, with an average 5-year survival rate of 32%, being of 6% for patients presenting distant metastasis. Despite the advances made in the treatment of GC, chemoresistance phenomena arise and promote recurrence, dissemination and dismal prognosis. In this context, gastric cancer stem cells (gCSCs), a small subset of cancer cells that exhibit unique characteristics, are decisive in therapy failure. gCSCs develop different protective mechanisms, such as the maintenance in a quiescent state as well as enhanced detoxification procedures and drug efflux activity, that make them insusceptible to current treatments. This, together with their self-renewal capacity and differentiation ability, represents major obstacles for the eradication of this disease. Different gCSC regulators have been described and used to isolate and characterize these cell populations. However, at the moment, no therapeutic strategy has achieved the effective targeting of gCSCs. This review will focus on the properties of cancer stem cells in the context of therapy resistance and will summarize current knowledge regarding the impact of the gCSC regulators that have been associated with GC chemoradioresistance.

The gut microbiota can be a potential regulator and treatment target of bone metastasis

The gut microbiota, an often forgotten organ, have a tremendous impact on human health. It has long been known that the gut microbiota are implicated in cancer development, and more recently, the gut microbiota have been shown to influence cancer metastasis to distant organs. Although one of the most common sites of distant metastasis is the bone, and the skeletal system has been shown to be a subject of interactions with the gut microbiota to regulate bone homeostasis, little research has been done regarding how the gut microbiota control the development of bone metastasis. This review will discuss the mechanisms through which the gut microbiota and derived microbial compounds (i) regulate gastrointestinal cancer disease progression and metastasis, (ii) influence skeletal remodeling and potentially modulate bone metastasis, and (iii) affect and potentially enhance immunotherapeutic treatments for bone metastasis.

Helicobacter pylori Infection and Serum Pepsinogen Level With the Risk of Gastric Precancerous Conditions: A Cross-sectional Study of High-risk Gastric Cancer Population in China

BACKGROUND AND AIM

Gastric precancerous conditions are generally considered to play an essential role in the gastric carcinogenesis cascade. This study identified risk factors of gastric precancerous conditions in a nationwide multicenter cross-sectional study.

METHODS

Individuals who made their visit to 115 hospitals in China for gastric cancer screening were recruited. Lifestyle habits and personal information were collected through a series of questionnaires. Serum biomarker test (pepsinogen I, pepsinogen II, gastrin-17, and anti-Helicobacter pylori immunoglobulin G antibody) and endoscopy were then performed. Risk factors for gastric precancerous conditions were identified by univariate and multivariate analyses.

RESULTS

Of 14,929 subjects eligible for analysis, 4477 (30.0%) developed gastric precancerous conditions and 405 (2.71%) developed gastric cancer. In multiple logistic regression, precancerous conditions were associated with advanced age [odds ratio (OR)=1.027; 95% confidence interval (Cl), 1.023-1.032; P<0.001], male gender (OR=1.303; 95% Cl, 1.188-1.429; P<0.001), H. pylori infection (OR=1.377; 95% Cl, 1.272-1.490, P<0.001), and smoking (OR=1.142; 95% Cl, 1.005-1.298, P=0.004), whereas they were inversely correlated with white meat intake (OR=0.731; 95% Cl, 0.673-0.794; P<0.001) and pepsinogen I level (30 to 70 subgroup OR=1.536; 95% Cl, 1.163-2.028; P=0.002; <30 subgroup OR=1.354; 95% Cl, 1.206-1.520; P<0.001). Also, the authors observed a statistically lower prevalence of reflux esophagitis (2.8% vs. 4.7%) and of gastric polyps (11.0% vs. 13.7%) in H. pylori-infected population.

CONCLUSIONS

Patients with H. pylori have a 1.4-fold higher risk of having gastric precancerous conditions. Besides, precancerous conditions were associated with advanced age, male gender, H. pylori infection, and smoking in a large population. However, regular white meat intake and higher pepsinogen I level were associated with reduced risk of having precancerous lesions.

The role of bone marrow-derived cells in the origin of liver cancer revealed by single-cell sequencing

Objective: Epithelial cancers often originate from progenitor cells, while the origin of hepatocellular carcinoma (HCC) is still controversial. HCC, one of the deadliest cancers, is closely linked with liver injuries and chronic inflammation, which trigger massive infiltration of bone marrow-derived cells (BMDCs) during liver repair. Methods: To address the possible roles of BMDCs in HCC origination, we established a diethylnitrosamine (DEN)-induced HCC model in bone marrow transplanted mice. Immunohistochemistry and frozen tissue immunofluorescence were used to verify DEN-induced HCC in the pathology of the disease. The cellular origin of DEN-induced HCC was further studied by single cell sequencing, single-cell nested PCR, and immunofluorescence-fluorescence in situ hybridization. Results: Studies by using single cell sequencing and biochemical analysis revealed that HCC cells in these mice were coming from donor mice BMDCs, and not from recipient mice. Furthermore, the copy numbers of mouse orthologs of several HCC-related genes previously reported in human HCC were also altered in our mouse model. DEN-induced HCCs exhibited a similar histological phenotype and genomic profile as human HCCs. Conclusions: These results suggested that BMDCs are an important origin of HCC, which provide important clues to HCC prevention, detection, and treatments.

Helicobacters and cancer, not only gastric cancer?

The Helicobacter genus actually comprises 46 validly published species divided into two main clades: gastric and enterohepatic Helicobacters. These bacteria colonize alternative sites of the digestive system in animals and humans, and contribute to inflammation and cancers. In humans, Helicobacter infection is mainly related to H. pylori, a gastric pathogen infecting more than half of the world's population, leading to chronic inflammation of the gastric mucosa that can evolve into two types of gastric cancers: gastric adenocarcinomas and gastric MALT lymphoma. In addition, H. pylori but also non-H. pylori Helicobacter infection has been associated with many extra-gastric malignancies. This review focuses on H. pylori and its role in gastric cancers and extra-gastric diseases, as well as malignancies induced by non-H. pylori Helicobacters. Their different virulence factors and their involvement in carcinogenesis is discussed. This review highlights the importance of both gastric and enterohepatic Helicobacters in gastrointestinal and liver cancers.

THBS4/integrin α2 axis mediates BM-MSCs to promote angiogenesis in gastric cancer associated with chronic Helicobacter pylori infection

Background: BM-MSCs contribute to Helicobacter pylori (H. pylori)-induced gastric cancer, but their mechanism is still unclear. The aim of our study was to investigate the specific role and mechanism of BM-MSCs in H. pylori-induced gastric cancer.

Main methods: Mice received total bone marrow transplants and were then infected with H. pylori. BM-MSCs were extracted and transplanted into the gastric serosal layer of mice chronically infected with H. pylori. Hematoxylin and eosin staining, immunohistochemistry staining and immunofluorescence were performed to detect tumor growth and angiogenesis in mouse stomach tissues. Chicken chorioallantoic membrane assays, xenograft tumor models, and human umbilical vein endothelial cell tube formation assays were used for in vivo and in vitro angiogenesis studies. THBS4 was screened from RNA-seq analysis of gastric tissues of BM-MSCs transplanted into H. pylori-infected mice.

Results: BM-MSCs can migrate to the site of chronic mucosal injury and promote tumor angiogenesis associated with chronic H. pylori infection. Migration of BM-MSCs to the site of chronic mucosal injury induced the upregulation of THBS4, which was also evident in human gastric cancer and correlated with increased blood vessel formation and worse outcome. The THBS4/integrin α2 axis promoted angiogenesis by facilitating the PI3K/AKT pathway in endothelial cells.

Conclusions: Our results revealed a novel proangiogenic effect of BM-MSCs in the chronic H. pylori infection microenvironment, primarily mediated by the THBS4/integrin α2 axis, which activates the PI3K/AKT pathway in endothelial cells and eventually induces the formation of new tumor vessels.

Helicobacter pylori and Gastric Cancer

Helicobacter pylori is present in approximately one-half of the world's population. There are significant differences in prevalence based on region, age, race/ethnicity, and socioeconomic status. H pylori is the most common cause of infection-related cancers. Studies have demonstrated the relationship between H pylori infection and gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma. H pylori has features and enzymatic properties allowing it to survive in the acidic stomach environment, and has specific virulence factors that promote an increased risk of gastric pathology. Eradication of H pylori is first-line therapy for mucosa-associated lymphoid tissue lymphoma and decreases the risk of gastric adenocarcinoma.

Knock down of BMSC-derived Wnt3a or its antagonist analogs attenuate colorectal carcinogenesis induced by chronic Fusobacterium nucleatum infection

By establishing the Fusobacterium nucleatum (F. nucleatum) infected-bone mesenchymal stem cells (BMSCs) transplantation model in APCMin/+ mice, we investigated the role of BMSCs in the development of intestinal tumors induced by F. nucleatum. ApcMin/++F. nucleatum + BMSCs mice showed increased susceptibility to intestinal tumors and accelerated tumor growth. BMSCs could also enhance tumor-initiating capability, invasive traits after F. nucleatum infection in vitro, and tumorigenicity in a nude murine model. Mechanistically, BMSCs were recruited to the submucosa, migrated to the mucosal layer, and might activate the canonical Wnt/β-catenin/TGIF axis signaling. Further mechanistic results illustrated increased production of the Wnt3a protein was found in ApcMin/++F. nucleatum + BMSCs mice, and BMSCs were likely the major source of Wnt3a. Intriguingly, a deletion of Wnt3a via BMSC interference or antagonist analogs led to a significantly attenuated capacity of ApcMin/++F. nucleatum mice to generate intestinal tumors. The findings suggest that BMSCs have the potential to migrate and accelerate F. nucleatum-induced colorectal tumorigenesis by modulating Wnt3a secretion; knockdown of BMSC-derived Wnt3a or antagonist analogs could attenuate carcinogenesis. Thus, Wnt3a might be a potential pharmaceutical target for the prevention and treatment of F. nucleatum-related colorectal cancer.

Alzheimer's Disease and Helicobacter pylori Infection: Inflammation from Stomach to Brain?

Despite extensive research, the origin of Alzheimer's disease (AD) remains unknown. The role of infectious pathogens has recently emerged. Epidemiological studies have shown that Helicobacter pylori infection increases the risk of developing AD. We hypothesized that H. pylori-induced gastritis may be associated with a systemic inflammation and finally neuroinflammation. C57BL/6 mice were infected with H. pylori (n = 15) or Helicobacter felis (n = 13) or left uninfected (n = 9) during 18 months. Gastritis, amyloid deposition, astroglial and microglial cell area, and systemic and brain cytokines were assessed. The infection (H. felis> H. pylori) induced a severe gastritis and an increased neuroinflammation but without brain amyloid deposition or systemic inflammation.

TAZ Controls Helicobacter pylori-Induced Epithelial-Mesenchymal Transition and Cancer Stem Cell-Like Invasive and Tumorigenic Properties

Helicobacter pylori infection, the main risk factor for gastric cancer (GC), leads to an epithelial–mesenchymal transition (EMT) of gastric epithelium contributing to gastric cancer stem cell (CSC) emergence. The Hippo pathway effectors yes-associated protein (YAP) and transcriptional co-activator with PDZ binding motif (TAZ) control cancer initiation and progression in many cancers including GC. Here, we investigated the role of TAZ in the early steps of H. pylori-mediated gastric carcinogenesis. TAZ implication in EMT, invasion, and CSC-related tumorigenic properties were evaluated in three gastric epithelial cell lines infected by H. pylori. We showed that H. pylori infection increased TAZ nuclear expression and transcriptional enhancer TEA domain (TEAD) transcription factors transcriptional activity. Nuclear TAZ and zinc finger E-box-binding homeobox 1 (ZEB1) were co-overexpressed in cells harboring a mesenchymal phenotype in vitro, and in areas of regenerative hyperplasia in gastric mucosa of H. pylori-infected patients and experimentally infected mice, as well as at the invasive front of gastric carcinoma. TAZ silencing reduced ZEB1 expression and EMT phenotype, and strongly inhibited invasion and tumorsphere formation induced by H. pylori. In conclusion, TAZ activation in response to H. pylori infection contributes to H. pylori-induced EMT, invasion, and CSC-like tumorigenic properties. TAZ overexpression in H. pylori-induced pre-neoplastic lesions and in GC could therefore constitute a biomarker of early transformation in gastric carcinogenesis.

Personalizing Gastric Cancer Screening With Predictive Modeling of Disease Progression Biomarkers

Gastric cancer (GC) remains the third most common cause of cancer-related death worldwide. Infection with Helicobacter pylori is responsible for over 70% of GC incidence; colonization induces chronic inflammation, which can facilitate progression to intestinal metaplasia, dysplasia, and GC (Correa pathway). Although H. pylori eradication is a necessary first step in GC prevention, some patients continue to progress to advanced stage disease if substantial tissue damage has occurred or inflammation persists. This progression is often asymptomatic until cancer reaches stage IV, yet efficient, cost-effective screening protocols for patients who present with early stages of the Correa pathway do not exist. Given the high interpatient heterogeneity in progression time through this pathway, such screening protocols must necessarily be personalized. This requires the identification of reliable and longitudinally assessable biomarkers of patient-specific progression. Several gastric stem cell (GSC) markers including CD44, CD133, and Lgr5 are upregulated in GC. Here we show a significant stepwise increase in immunohistochemical staining for these markers in biopsies at different stages of the Correa pathway, suggesting GSC fraction to be a promising candidate biomarker for early detection of malignant transformation. We present a mathematical model capable of both simulating clinically observed increases in GSC fraction in longitudinal biopsy samples of individual patients, and forecasting patient-specific disease progression trajectories based only on characteristics identified from immunohistochemistry at initial presentation. From these forecasts, personalized screening schedules may be identified that would allow early stratification of high-risk patients, and potentially earlier detection of dysplasia or early-stage GC.

Whole-Genome Sequencing and Bioinformatics as Pertinent Tools to Support Helicobacteracae Taxonomy, Based on Three Strains Suspected to Belong to Novel Helicobacter Species

The present study describes three putative novel species received at the French National Reference Center for Campylobacters & Helicobacters (CNRCH). The CNRCH 2005/566H strain was isolated in 2005 from the feces of a patient with a hepatocellular carcinoma and gastroenteritis. Strain 48519 was isolated in 2017 from the blood of a male patient suffering from a bacteremia. Strain Cn23e was isolated from a gastric biopsy from a dog suffering from chronic gastritis. Biochemical and growth characteristics and electron microscopy for these three strains were studied. Their genomes were also sequenced. gyrA based phylogeny built with 72 nucleotide sequences placed CNRCH 2005/566H among the unsheathed enterohepatic helicobacters, close to Helicobacter valdiviensis; strain 48519 among the sheathed enterohepatic helicobacters, close to Helicobacter cinaedi; and strain Cn23e among gastric helicobacters, close to Helicobacter felis. 16S rRNA gene phylogeny showed similar results, but with weak discriminant strength. Average nucleotide identity and in silico DNA–DNA hybridization analyses revealed that CNRCH 2005/566H and 48519 strains belong to new putative species, but confirmed that Cn23e corresponds to H. felis. Cn23e was able to infect C57BL6 mice and to induce gastric inflammation. The genomics data, together with their different morphological and biochemical characteristics, revealed that these two strains represent novel Helicobacter species. We propose the following names: ‘Helicobacter burdigaliensis,’ with the type strain CNRCH 2005/566H ( =CECT 8850 =CIP 111660), and ‘Helicobacter labetoulli,’ with the type strain 48519 ( =CCUG 73475 =CIP 1111659). This study highlights that the diversity of the Helicobacteraceae family remains to be fully explored.

The Gastrointestinal Tumor Microenvironment: An Updated Biological and Clinical Perspective

Gastrointestinal cancers are still responsible for high numbers of cancer-related deaths despite advances in therapy. Tumor-associated cells play a key role in tumor biology, by supporting or halting tumor development through the production of extracellular matrix, growth factors, cytokines, and extracellular vesicles. Here, we review the roles of these tumor-associated cells in the initiation, angiogenesis, immune modulation, and resistance to therapy of gastrointestinal cancers. We also discuss novel diagnostic and therapeutic strategies directed at tumor-associated cells and their potential benefits for the survival of these patients.

Transformed bone marrow cells generate neoplasms of distinct histogenesis. a murine model of cancer transplantation

The last several years have witnessed renewed interest regarding the contribution of cancer stem cells in tumorigenesis and neoplastic heterogeneity. It has been reported that patients who undergo bone marrow transplantation are more prone to develop a malignancy during their life time; usually hematological tumors, but solid neoplasms may also develop, which in certain instances are donor-derived. It has also been well documented that multipotent bone marrow derived cells can migrate to diverse organs, differentiating into various histological lineages. The present study reports an experimental syngeneic transplantation model, using fluorescently tagged bone marrow cells from p53 null male mice into female wild-type counterparts. We found that transplanted non-neoplastic mutant bone marrow cells can generate tumors of distinct histogenesis, including thymic lymphomas, sarcomas, and carcinomas after carcinogen induction, providing evidence that multipotent cancer-prone stem cells can reside in the bone marrow and are transplantable.

The Hippo Kinase LATS2 Controls Helicobacter pylori-Induced Epithelial-Mesenchymal Transition and Intestinal Metaplasia in Gastric Mucosa

BACKGROUND & AIMS

Gastric carcinoma is related mostly to CagA+-Helicobacter pylori infection, which disrupts the gastric mucosa turnover and elicits an epithelial-mesenchymal transition (EMT) and preneoplastic transdifferentiation. The tumor suppressor Hippo pathway controls stem cell homeostasis; its core, constituted by the large tumor suppressor 2 (LATS2) kinase and its substrate Yes-associated protein 1 (YAP1), was investigated in this context.

METHODS

Hippo, EMT, and intestinal metaplasia marker expression were investigated by transcriptomic and immunostaining analyses in human gastric AGS and MKN74 and nongastric immortalized RPE1 and HMLE epithelial cell lines challenged by H pylori, and on gastric tissues of infected patients and mice. LATS2 and YAP1 were silenced using small interfering RNAs. A transcriptional enhanced associated domain (TEAD) reporter assay was used. Cell proliferation and invasion were evaluated.

RESULTS

LATS2 and YAP1 appear co-overexpressed in the infected mucosa, especially in gastritis and intestinal metaplasia. H pylori via CagA stimulates LATS2 and YAP1 in a coordinated biphasic pattern, characterized by an early transient YAP1 nuclear accumulation and stimulated YAP1/TEAD transcription, followed by nuclear LATS2 up-regulation leading to YAP1 phosphorylation and targeting for degradation. LATS2 and YAP1 reciprocally positively regulate each other's expression. Loss-of-function experiments showed that LATS2 restricts H pylori-induced EMT marker expression, invasion, and intestinal metaplasia, supporting a role of LATS2 in maintaining the epithelial phenotype of gastric cells and constraining H pylori-induced preneoplastic changes.

CONCLUSIONS

H pylori infection engages a number of signaling cascades that alienate mucosa homeostasis, including the Hippo LATS2/YAP1/TEAD pathway. In the host-pathogen conflict, which generates an inflammatory environment and perturbations of the epithelial turnover and differentiation, Hippo signaling appears as a protective pathway, limiting the loss of gastric epithelial cell identity that precedes gastric carcinoma development.

Mesenchymal stem cells co-cultured with colorectal cancer cells showed increased invasive and proliferative abilities due to its altered p53/TGF-β1 levels

Signaling between cancer cells, their neighboring cells, and mesenchymal stem cells (MSCs) forms the tumor microenvironment. The complex heterogeneity of this microenvironment varies depending on the tumor type and its origins. However, most of the existing cancer-based studies have focused on cancer cells. In this study, we used a direct co-culture system (cross-talk signaling) to induce cross-interaction between cancer cells and mesenchymal stem cells. This induced deformation of MSCs. MSCs showed a diminished ability to maintain homeostasis. In particular, increase in the invasion ability of MSCs by TGF-β1 and decrease in p53, which plays a key role in cancer development, is an important discovery. It can thus be deduced that blocking these changes can effectively inhibit metastatic colorectal cancer. In conclusion, understanding the interactions and changes in MSCs associated with cancer will help develop novel therapeutic strategies for cancer.

Cytolethal distending toxin induces the formation of transient messenger-rich ribonucleoprotein nuclear invaginations in surviving cells

Humans are frequently exposed to bacterial genotoxins involved in digestive cancers, colibactin and Cytolethal Distending Toxin (CDT), the latter being secreted by many pathogenic bacteria. Our aim was to evaluate the effects induced by these genotoxins on nuclear remodeling in the context of cell survival. Helicobacter infected mice, coculture experiments with CDT- and colibactin-secreting bacteria and hepatic, intestinal and gastric cells, and xenograft mouse-derived models were used to assess the nuclear remodeling in vitro and in vivo. Our results showed that CDT and colibactin induced-nuclear remodeling can be associated with the formation of deep cytoplasmic invaginations in the nucleus of giant cells. These structures, observed both in vivo and in vitro, correspond to nucleoplasmic reticulum (NR). The core of the NR was found to concentrate ribosomes, proteins involved in mRNA translation, polyadenylated RNA and the main components of the complex mCRD involved in mRNA turnover. These structures are active sites of mRNA translation, correlated with a high degree of ploidy, and involve MAPK and calcium signaling. Additional data showed that insulation and concentration of these adaptive ribonucleoprotein particles within the nucleus are dynamic, transient and protect the cell until the genotoxic stress is relieved. Bacterial genotoxins-induced NR would be a privileged gateway for selected mRNA to be preferably transported therein for local translation. These findings offer new insights into the context of NR formation, a common feature of many cancers, which not only appears in response to therapies-induced DNA damage but also earlier in response to genotoxic bacteria.

Humans are frequently exposed to bacterial genotoxins linked to cancers, colibactin and Cytolethal Distending Toxin (CDT). These genotoxins induce DNA damage and can promote formation of nucleoplasmic reticulum (NR), deeply invaginated in the nucleoplasm of giant nuclei both in vivo and in vitro. Our cellular models showed that these structures can be observed together with profound nuclear reorganization corresponding to remodeling of nuclear material. The core of the genotoxin-induced NRs concentrates protein production machinery of the cell as well as controlling elements of protein turnover. These genotoxin-induced dynamic structures may also be signaling hubs controlling mRNA turnover and translation of selected mRNAs and thus correspond to a privileged gateway for the synthesis of selected mRNA which are preferentially transported from the nucleus through pores and translated therein. These transient and reversible hubs allow the cell to pause and repair the DNA damage caused by bacterial genotoxins in order to maintain cell survival. As NR formation is a common feature of many cancers, similar mechanism could occur and contribute to the resistance of cancer cells to radiotherapies and some chemotherapies aimed at inducing DNA damage.

Crosstalk Between DNA Damage and Inflammation in the Multiple Steps of Gastric Carcinogenesis

Over the last years, intensive investigations in molecular biology and cell physiology extended tremendously the knowledge about the association of inflammation and cancer. In frame of this paradigm, the human pathogen Helicobacter pylori triggers gastritis and gastric ulcer disease, and contributes to the development of gastric cancer. Mechanisms, by which the bacteria-induced inflammation in gastric mucosa leads to intestinal metaplasia and carcinoma, are represented in this review. An altered cell-signaling response and increased production of free radicals by epithelial and immune cells account for the accumulation of DNA damage in gastric mucosa, if infection stays untreated. Host genetics and environmental factors, especially diet, can accelerate the process, which offers the opportunity of intervention based on a balanced nutrition. It is supposed that inflammation might influence stem- or progenitor cells in gastric tissue predisposing for metaplasia or tumor relapse. Herein, DNA is strongly mutated and labile, which restricts therapy options. Thus, the understanding of the mechanisms that underlie gastric carcinogenesis will be of preeminent importance for the development of strategies for screening and early detection. As most gastric cancer patients face late-stage disease with a poor overall survival, the development of multi-targeted therapeutic intervention strategies is a major challenge for the future.

The Role of MicroRNAs in the Regulation of Gastric Cancer Stem Cells: A Meta-Analysis of the Current Status

Gastric cancer (GC) remains one of the major causes of cancer-related mortality worldwide. As for other types of cancers, several limitations to the success of current therapeutic GC treatments may be due to cancer drug resistance that leads to tumor recurrence and metastasis. Increasing evidence suggests that cancer stem cells (CSCs) are among the major causative factors of cancer treatment failure. The research of molecular CSC mechanisms and the regulation of their properties have been intensively studied. To date, molecular gastric cancer stem cell (GCSC) characterization remains largely incomplete. Among the GCSC-targeting approaches to overcome tumor progression, recent studies have focused their attention on microRNA (miRNA). The miRNAs are short non-coding RNAs which play an important role in the regulation of numerous cellular processes through the modulation of their target gene expression. In this review, we summarize and discuss recent findings on the role of miRNAs in GCSC regulation. In addition, we perform a meta-analysis aimed to identify novel miRNAs involved in GCSC homeostasis.

The study of drug resistance properties of ABCG2 (ATP-binding cassette G2) in contact with thymoquinone, gallic acid, and hesperetin antioxidants

Introduction: ATP-binding cassette (ABC) transporters are a group of intra membrane proteins that play key roles in the transmission and exchange of vital compounds on both sides of the membrane. These proteins can specially transport anti-cancer drugs out of cancer cells. ABCG2 is a member of this family that is extremely expressed in many cancers. This study, aims to evaluate the binding affinity of three antioxidants thymoquinone (TQ), gallic acid (GA), and hesperetin (HP) to ABCG2 compared with an anti-cancer drug, mitoxantrone (Mit), to export cells. Methods: The PDB file of ABCG2 was obtained from the protein data bank server (http://www.rcsb.org) with ID: 5NJ3. After 200 stages of molecular docking running on ABCG2 protein in AutoDock v.4.2 software, the amino acids involved in the binding site of each compound were identified using the LigPlot+ software. Results: HP had the lowest (-6.36 kcal/mol) and GA had the highest (-3.93 kcal/mol) binding energy in comparison with Mit (-0.06 kcal/mol) for binding to ABCG2. Effective concentration required to perform the reaction between ABCG2 was higher in GA (1.31 mM) than TQ (42.69 μM) and HP (21.74 μM). GA, HP, and TQ formed 17, 18, and 22 hydrogen and hydrophobic bonds at the binding site of ABCG2. Conclusion: It seems that GA has the lowest affinity to make contact with ABCG2 binding site. So, GA tends to remain in the cell but TQ and HP tend to leave the cell easily via ABCG2 transporter.

Pathogenicity of Helicobacter pylori in cancer development and impacts of vaccination

Helicobacter pylori affect around 50% of the population worldwide. More importantly, the gastric infection induced by this bacterium is deemed to be associated with the progression of distal gastric carcinoma and gastric mucosal lymphoma in the human. H. pylori infection and its prevalent genotype significantly differ across various geographical regions. Based on numerous virulence factors, H. pylori can target different cellular proteins to modulate the variety of inflammatory responses and initiate numerous "hits" on the gastric mucosa. Such reactions lead to serious complications, including gastritis and peptic ulceration, gastric cancer and gastric mucosa-associated lymphoid structure lymphoma. Therefore, H. pylori have been considered as the type I carcinogen by the Global Firm for Research on Cancer. During the two past decades, different reports revealed that H. pylori possess oncogenic potentials in the gastric mucosa through a complicated interplay between the bacterial factors, various facets, and the environmental factors. Accordingly, numerous signaling pathways could be triggered in the development of gastrointestinal diseases (e.g., gastric cancer). Therefore, the main strategy for the treatment of gastric cancer is controlling the disease far before its onset using preventive/curative vaccination. Increasing the efficiency of vaccines may be achieved by new trials of vaccine modalities, which is used to optimize the cellular immunity. Taken all, H. pylori infection may impose severe complications, for resolving of which extensive researches are essential in terms of immune responses to H. pylori. We envision that H. pylori-mediated diseases can be controlled by advanced vaccines and immunotherapies.

Bone marrow-derived epithelial cells and hair follicle stem cells contribute to development of chronic cutaneous neoplasms

We used allogeneic bone marrow transplantation (BMT) and a mouse multistage cutaneous carcinogenesis model to probe recruitment of bone marrow-derived epithelial cells (BMDECs) in skin tumors initiated with the carcinogen, dimethylbenz[a]anthracene (DMBA), and promoted with 12-O-tetradecanolyphorbol-13-acetate (TPA). BMDECs clustered in the lesional epithelium, expressed cytokeratins, proliferated, and stratified. We detected cytokeratin induction in plastic-adherent bone marrow cells (BMCs) cultured in the presence of filter-separated keratinocytes (KCs) and bone morphogenetic protein 5 (BMP5). Lineage-depleted BMCs migrated towards High Mobility Group Box 1 (HMGB1) protein and epidermal KCs in ex vivo invasion assays. Naive female mice receiving BMTs from DMBA-treated donors developed benign and malignant lesions after TPA promotion alone. We conclude that BMDECs contribute to the development of papillomas and dysplasia, demonstrating a systemic contribution to these lesions. Furthermore, carcinogen-exposed BMCs can initiate benign and malignant lesions upon tumor promotion. Ultimately, these findings may suggest targets for treatment of non-melanoma skin cancers.

Efficiency of All-Trans Retinoic Acid on Gastric Cancer: A Narrative Literature Review

Gastric cancer (GC) is the third leading cause of cancer-related death worldwide with a five-year survival rate of around 25%, and 4% when diagnosed at a metastatic stage. Cancer stem cells (CSC) have recently been characterized as being responsible for resistance to radio/chemotherapies and metastasis formation, opening up perspectives for new targeted therapies. Those CSCs express biomarkers such as cluster of differentiation 44 (CD44) and display high aldehyde dehydrogenase activity that converts vitamin A-derived retinal into retinoic acids. All-trans retinoic acid (ATRA), which has pro-differentiating properties, has revolutionized the prognosis of acute promyelotic leukemia by increasing its remission rate from 15% to 85%. Recent studies have started to show that ATRA also has an anti-tumoral role on solid cancers such as GC. The purpose of this review is therefore to summarize the work that evaluated the effects of ATRA in GC and to evaluate whether its anti-cancerous action involves gastric CSCs targeting. It has been demonstrated that ATRA can block the cell cycle, enhance apoptosis, and decrease gastric CSCs properties in GC cell lines, tumorspheres, and patient-derived xenograft mice models. Therefore, retinoids and new synthetic retinoids seem to be a promising step forward in targeted therapy of gastric CSC in combination with existing chemotherapies. Future studies should probably focus on these points.

Tumor heterogeneity of gastric cancer: From the perspective of tumor-initiating cell

Gastric cancer (GC) remains one of the most common and malignant types of cancer due to its rapid progression, distant metastasis, and resistance to conventional chemotherapy, although efforts have been made to understand the underlying mechanism of this resistance and to improve clinical outcome. It is well recognized that tumor heterogeneity, a fundamental feature of malignancy, plays an essential role in the cancer development and chemoresistance. The model of tumor-initiating cell (TIC) has been proposed to explain the genetic, histological, and phenotypical heterogeneity of GC. TIC accounts for a minor subpopulation of tumor cells with key characteristics including high tumorigenicity, maintenance of self-renewal potential, giving rise to both tumorigenic and non-tumorigenic cancer cells, and resistance to chemotherapy. Regarding tumor-initiating cell of GC (GATIC), substantial studies have been performed to (1) identify the putative specific cell markers for purification and functional validation of GATICs; (2) trace the origin of GATICs; and (3) decode the regulatory mechanism of GATICs. Furthermore, recent studies demonstrate the plasticity of GATIC and the interaction between GATIC and its surrounding factors (TIC niche or tumor microenvironment). All these investigations pave the way for the development of GATIC-targeted therapy, which is in the phase of preclinical studies and clinical trials. Here, we interpret the heterogeneity of GC from the perspectives of TIC by reviewing the above-mentioned fundamental and clinical studies of GATICs. Problems encountered during the GATIC investigations and the potential solutions are also discussed.

RIP3 mediates IL-33 production in gastric epithelial cells with intestinal metaplasia

AIM

To explore the relationship between receptor-interacting protein kinase 3 (RIP3) signaling pathway and gastric intestinal metaplasia (GIM), and the regulatory effect of this signaling pathway on inflammatory cytokines.

METHODS

Gastric tissues from healthy controls, patients with chronic non-atrophic gastritis, patients with GIM, and patients with dysplasia were collected to detect the expression of RIP3 in GIM by immunohistochemistry and RT-PCR. Human gastric epithelial cell line GES-1 was stimulated with sodium deoxycholate (DCA) to observe the relationship between CDX2, a key gene involved in intestinal metaplasia, and RIP3 signaling pathway. The regulation of inflammatory cytokines by RIP3 was also assessed.

RESULTS

Compared with the control and chronic non-atrophic gastritis groups, the expression of RIP3 mRNA in the gastric mucosa of GIM patients and dysplasia patients was up-regulated, and the expression of RIP3 protein in the gastric epithelium of GIM patients and dysplasia patients was also up-regulated. In GES-1 cells stimulated with DCA, the expression of CDX2 protein and the RIP3 signaling pathway-associated proteins was increased in a concentration-dependent manner, accompanied by up-regulation of IL-33 expression. Necrostatin-1 (Nec-1), a specific inhibitor of the RIP3 signaling pathway, had no effect on CDX2 expression, but significantly down-regulated the expression of RIP3 and IL-33.

CONCLUSION

RIP3 has no effect on the occurrence of GIM, but it may affect GIM progression by regulating the expression of IL-33 in gastric epithelial cells with intestinal metaplasia, suggesting that it may be a potential therapeutic target for preventing GIM progression.

A signalling cascade of IL-33 to IL-13 regulates metaplasia in the mouse stomach

OBJECTIVE

Alternatively activated macrophages (M2) are associated with the progression of spasmolytic polypeptide-expressing metaplasia (SPEM) in the stomach. However, the precise mechanism(s) and critical mediators that induce SPEM are unknown.

DESIGN

To determine candidate genes important in these processes, macrophages from the stomach corpus of mice with SPEM (DMP-777-treated) or advanced SPEM (L635-treated) were isolated and RNA sequenced. Effects on metaplasia development after acute parietal cell loss induced by L635 were evaluated in interleukin (IL)-33, IL-33 receptor (ST2) and IL-13 knockout (KO) mice.

RESULTS

Profiling of metaplasia-associated macrophages in the stomach identified an M2a-polarised macrophage population. Expression of IL-33 was significantly upregulated in macrophages associated with advanced SPEM. L635 induced metaplasia in the stomachs of wild-type mice, but not in the stomachs of IL-33 and ST2 KO mice. While IL-5 and IL-9 were not required for metaplasia induction, IL-13 KO mice did not develop metaplasia in response to L635. Administration of IL-13 to ST2 KO mice re-established the induction of metaplasia following acute parietal cell loss.

CONCLUSIONS

Metaplasia induction and macrophage polarisation after parietal cell loss is coordinated through a cytokine signalling network of IL-33 and IL-13, linking a combined response to injury by both intrinsic mucosal mechanisms and infiltrating M2 macrophages.

Native and bone marrow-derived cell mosaicism in gastric carcinoma in H. pylori-infected p27-deficient mice

Objective

Chronic Helicobacter pylori (H. pylori) infection promotes non-cardia gastric cancer. Some mouse models suggest that bone marrow derived cells (BMDC) contribute to Helicobacter-associated gastric carcinogenesis. We determined whether this increased susceptibility to Helicobacter-induced gastric carcinogenesis of p27-deficient mice is dependent upon their p27-null BMDC or their p27-null gastric epithelial cells.

Design

Female mice (recipients) were irradiated and transplanted with BMDC from male donors. Wild type (WT) mice in group 1 (control) received BMDC from male GFP-transgenic mice. Female WT and p27 KO mice were engrafted with male p27KO mice BMDC (Group 2) or GFP-transgenic WT BMDC (Group 3). Recipients were infected with H. pylori SS1 for one year.

Results

Mice lacking p27 in either the BM pool or gastric epithelium developed significantly more advanced gastric pathology, including high-grade dysplasia. Co-staining of donor BMDC in dysplastic gastric glands was confirmed by immunofluorescence. Gastric expression of IL-1 beta protein was reduced in groups 2 and 3 (p < 0.05 vs control) whereas expression of IFN-γ and chemokines MIP-1 beta, MIG, IP-10 and RANTES in group 2 were significantly higher than group 3.

Conclusions

Both bone marrow-derived and gastric epithelial cells contribute to the increased gastric cancer susceptibility of p27-deficient H. pylori-infected mice.

Multiscale positive feedbacks contribute to unidirectional gastric disease progression induced by helicobacter pylori infection

Background

Helicobacter Pylori (HP) is the most common risk factor for gastric cancer. Nearly half the world’s population is infected with HP, but only a small percentage of those develop significant pathology. The bacteria itself does not directly cause cancer; rather it promotes an environment that is conducive to tumor formation. Upon infection, HP induces transcriptional changes in the host, leading to enhanced proliferation and host immune response. In addition, HP causes direct damage to gastric epithelial cells.

Results

We present a multiscale mechanistic model of HP induced changes. The model includes four modules representing the host transcriptional changes in response to infection, gastric atrophy, the Hedgehog pathway response, and the restriction point that controls cell cycle. This model was able to recapture a number of literature reported observations and was used as an “in silico” representation of the biological system for further analysis. Dynamical analysis of the model revealed that HP might induce the activation of multiple interplayed positive feedbacks, which in turn might result in a “ratchet ladder” system that promotes a unidirectional progression of gastric disease.

Conclusions

The current multiscale model is able to recapitulate the observed experimental features of HP host interactions and provides dynamic insights on the epidemiologically observed heterogeneity in disease progression. This model provides a solid framework that can be further expanded and validated to include additional experimental evidence, to understand the complex multi-pathway interactions characterizing HP infection, and to design novel treatment protocols for HP induced diseases.

Electronic supplementary material

The online version of this article (10.1186/s12918-017-0497-y) contains supplementary material, which is available to authorized users.

Species-specific role of gene-adjacent retroelements in human and mouse gastric carcinogenesis

Helicobacter pylori (HP) infection promotes the recruitment of bone marrow stem cells into chronic gastritis lesions. Some of these marrow stem cells can differentiate into gastric epithelial cells and neoplastic cells. We propose that HP-associated methylation could stabilize trans-differentiation of marrow-derived stem cells and that an unstable methylation status is associated with a risk of gastric cancer. Pathobiologic behavior of experimental mouse gastric cancer is mild compared to invasive and metastatic human gastric cancer. Differences in epigenetic stabilization of adult cell phenotypes between humans and mice could provide a foundation to explore the development of invasive and metastatic gastric cancer. Retroelements are highly repetitive sequences that play an essential role in the generation of species diversity. In this review, we analyzed retroelements adjacent to human and mouse housekeeping genes and proposed a possible epigenetic mechanism for HP-associated carcinogenesis.

A global burden of gastric cancer: the major impact of China

Gastric cancer (GC) is a highly aggressive cancer and a major cause of cancer-related deaths worldwide. Approximately half of the world's GC cases and deaths occur in china. GC presents challenges in early diagnosis and effective therapy due to a lack of understanding of the underlying molecular biology. The primary goals of this review are to outline current GC research in china and describe future trends in this field. Areas covered: This review mainly focuses on a series of GC-related advances China has achieved. Considerable progress has been made in understanding the role of H. pylori in GC by a series of population-based studies in well-established high-risk areas; A few germline and somatic alterations have been identified by 'omics' studies; Studies on the mechanisms of malignant phenotypes have helped us to form an in-depth understanding of GC and advance drug discovery. Moreover, identification of potential biomarkers and targeted therapies have facilitated the diagnosis and treatment of GC. However, many challenges remain. Expert commentary: To combat GC, sufficient funding is important. More attention should be paid on early diagnosis and the discovery of novel efficient biomarkers and the development of biomarker-based or targeted therapeutics in GC.

Deregulation of MicroRNAs in Gastric Lymphomagenesis Induced in the d3Tx Mouse Model of Helicobacter pylori Infection

Helicobacter pylori infection is considered as an excellent model of chronic inflammation-induced tumor development. Our project focuses on gastric MALT lymphoma (GML) related to H. pylori infection and mediated by the chronic inflammatory process initiated by the infection. Recently, microRNAs (miRNAs) have emerged as a new class of gene regulators, which play key roles in inflammation and carcinogenesis acting as oncogenes or tumor suppressors. Their precise characterization in the development of inflammation and their contribution in regulating host cells responses to infection by H. pylori have been little explored. Our goal was to analyze the changes in miRNAs in a GML mouse model using BALB/c mice thymectomized at day 3 post-birth (d3Tx model) and to clarify their implication in GML pathogenesis. PCR array followed by RT-qPCR identified five miRNAs (miR-21a, miR-135b, miR-142a, miR-150, miR-155) overexpressed in the stomachs of GML-developing d3Tx mice infected by H. pylori. The analysis of their putative targets allowed us to identify TP53INP1, an anti-proliferative and pro-apoptotic protein, as a common target of 4 of the 5 up-regulated miRNAs. We postulate that these miRNAs may act in synergy to promote the development of GML. miR-142a was also overexpressed in mouse sera samples and therefore could serve as a diagnostic marker. In situ hybridization on gastric samples with miR-142a revealed a global up-regulation of this miRNA by the tumor microenvironment at the lymphoma stage. Dysregulation of miR-21a, miR-135b, miR-142a, miR-150, miR-155 could play a critical role in the pathogenesis of GML and might offer potential applications as therapeutic targets and novel biomarkers for this disease.

A unified model of the hierarchical and stochastic theories of gastric cancer

Gastric cancer (GC) is a life-threatening disease worldwide. Despite remarkable advances in treatments for GC, it is still fatal to many patients due to cancer progression, recurrence and metastasis. Regarding the development of novel therapeutic techniques, many studies have focused on the biological mechanisms that initiate tumours and cause treatment resistance. Tumours have traditionally been considered to result from somatic mutations, either via clonal evolution or through a stochastic model. However, emerging evidence has characterised tumours using a hierarchical organisational structure, with cancer stem cells (CSCs) at the apex. Both stochastic and hierarchical models are reasonable systems that have been hypothesised to describe tumour heterogeneity. Although each model alone inadequately explains tumour diversity, the two models can be integrated to provide a more comprehensive explanation. In this review, we discuss existing evidence supporting a unified model of gastric CSCs, including the regulatory mechanisms of this unified model in addition to the current status of stemness-related targeted therapy in GC patients.

The self-renewal signaling pathways utilized by gastric cancer stem cells

Gastric cancer is a leading cause of cancer-related mortality worldwide. Cancer stem cells are the source of tumor recurrence and metastasis. Self-renewal is a marker of cancer stem cells and also the basis of long-lasting survival and tumor progression. Although the mechanism of gastric cancer stem cell self-renewal is not clear, there are several signaling pathways and environmental factors known to be involved. This mini review describes recent developments in the self-renewal signaling pathway of gastric cancer stem cell research. Advancements made in this field of research will likely support the development of novel therapeutic strategies for gastric cancer.

Clinical significance of spasmolytic polypeptide-expressing metaplasia and intestinal metaplasia in Epstein-Barr virus-associated and Epstein-Barr virus-negative gastric cancer

Spasmolytic polypeptide-expressing metaplasia (SPEM) and intestinal metaplasia (IM) have been recognized as neoplastic precursors in gastric carcinogenesis. We explored the relationship between SPEM and IM in Epstein-Barr virus-associated (EBVaGC) and Epstein-Barr virus-negative (EBVnGC) gastric cancer. Sixty-four EBVaGC and one hundred and fifty-four EBVnGC patients were included. EBV positivity was identified using Epstein-Barr virus-encoded RNA-1 in situ hybridization. SPEM was subclassified into absent, early, and advanced SPEM. Acute and chronic inflammation was graded as absent, mild, moderate, and marked. Univariate and multivariate logistic regression analyses were conducted to analyze the correlation between SPEM, IM, and inflammation. Our study revealed that SPEM was detected in 87.5% EBVaGC and 85.1% EBVnGC patients. Distribution of patients according to the SPEM classification was significantly different between EBVaGC and EBVnGC groups (P=.038). IM was observed less frequently in EBVaGC when compared with EBVnGC patients (P<.001). No difference was observed between EBVaGC and EBVnGC in the levels of acute and chronic inflammation. A positive correlation between IM and SPEM status was observed in both EBVaGC and EBVnGC patients. Furthermore, advanced SPEM was an independent influential factor to IM in EBVnGC (P=.013). In conclusion, SPEM was associated with both EBVaGC and EBVnGC more frequently than IM. Moreover, advanced SPEM had a stronger association with IM than early SPEM in EBVnGC. These results suggest that identification of SPEM should be used as a high-risk indicator for detecting early gastric carcinoma, and should be brought to the attention of pathologists and clinicians.

Deletion of IQGAP1 promotes Helicobacter pylori-induced gastric dysplasia in mice and acquisition of cancer stem cell properties in vitro

Helicobacter pylori infection is responsible for gastric carcinogenesis but host factors are also implicated. IQGAP1, a scaffolding protein of the adherens junctions interacting with E-cadherin, regulates cellular plasticity and proliferation. In mice, IQGAP1 deficiency leads to gastric hyperplasia. The aim of this study was to elucidate the consequences of IQGAP1 deletion on H. pylori-induced gastric carcinogenesis.Transgenic mice deleted for iqgap1 and WT littermates were infected with Helicobacter sp., and histopathological analyses of the gastric mucosa were performed. IQGAP1 and E-cadherin expression was evaluated in gastric tissues and in gastric epithelial cell lines in response to H. pylori infection. The consequences of IQGAP1 deletion on gastric epithelial cell behaviour and on the acquisition of cancer stem cell (CSC)-like properties were evaluated. After one year of infection, iqgap1+/- mice developed more preneoplastic lesions and up to 8 times more gastro-intestinal neoplasia (GIN) than WT littermates. H. pylori infection induced IQGAP1 and E-cadherin delocalization from cell-cell junctions. In vitro, knock-down of IQGAP1 favoured the acquisition of a mesenchymal phenotype and CSC-like properties induced by H. pylori infection.Our results indicate that alterations in IQGAP1 signalling promote the emergence of CSCs and gastric adenocarcinoma development in the context of an H. pylori infection.