Helicobacter pylori CagA protein induces factors involved in the epithelial to mesenchymal transition (EMT) in infected gastric epithelial cells in an EPIYA- phosphorylation-dependent manner

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.

Biofilm and Cancer: Interactions and Future Directions for Cancer Therapy

There is a growing body of evidence supporting the significant role of bacterial biofilms in the pathogenesis of various human diseases, including cancer. Biofilms are polymicrobial communities enclosed within an extracellular matrix composed of polysaccharides, proteins, extracellular DNA, and lipids. This complex matrix provides protection against antibiotics and host immune responses, enabling the microorganisms to establish persistent infections. Moreover, biofilms induce anti-inflammatory responses and metabolic changes in the host, further facilitating their survival. Many of these changes are comparable to those observed in cancer cells. This review will cover recent research on the role of bacterial biofilms in carcinogenesis, especially in colorectal (CRC) and gastric cancers, emphasizing the shared physical and chemical characteristics of biofilms and cancer. This review will also discuss the interactions between bacteria and the tumor microenvironment, which can facilitate oncogene expression and cancer progression. This information will provide insight into developing new therapies to identify and treat biofilm-associated cancers, such as utilizing bacteria as delivery vectors, using bacteria to upregulate immune function, or more selectively targeting biofilms and cancer for their shared traits.

Induction of MMP-3 and MMP-9 expression during Helicobacter pylori infection via MAPK signaling pathways

BACKGROUND AND AIMS

Helicobacter pylori (H. pylori)-induced gastric pathology involves remodeling of extracellular matrix mediated by aberrant activity of matrix metalloproteinases (MMPs). We have previously shown that in vitro H. pylori infection leads to MMP-3 and MMP-9 overexpression, associated with phosphorylation of bacterial oncoprotein CagA. We extended these findings in an in vivo model of H. pylori infection and further assessed the involvement of MAPK pathways in MMP expression.

MATERIALS AND METHODS

C57BL/6 mice were infected with H. pylori strains HPARE, HPARE ΔCagA, and SS1, for 6 and 9 months. Transcriptional expression of Mmp-3 and Mmp-9 was evaluated via qPCR while respective protein levels in the gastric mucosa were determined immunohistochemically. Epithelial cell lines AGS and GES-1 were infected with H. pylori strain P12 in the presence of chemical inhibitors of JNK, ERK1/2, and p38 pathways, for 24 h. mRNA and protein expression of MMP-3 and MMP-9 were determined via qPCR and Western blot, respectively.

RESULTS

We observed transcriptional activation of Mmp-3 and Mmp-9 as well as aberrant MMP-3 and MMP-9 protein expression in murine gastric tissue following H. pylori infection. CagA expression was associated with MMP upregulation, particularly during the early time points of infection. We found that inhibition of ERK1/2 resulted in reduced mRNA and protein expression of MMP-3 and MMP-9 during H. pylori infection, in both cell lines. Expressed protein levels of both MMPs were also found reduced in the presence of JNK pathway inhibitors in both cell lines. However, p38 inhibition resulted in a more complex effect, probably attributed to the accumulation of phospho-p38 and increased phospho-ERK1/2 activity due to crosstalk between MAPK pathways.

CONCLUSIONS

H. pylori colonization leads to the upregulation of MMP-3 and MMP-9 in vivo, which primarily involves ERK1/2 and JNK pathways. Therefore, their inhibition may potentially offer a protective effect against gastric carcinogenesis and metastasis.

Gastric Epithelial Barrier Disruption, Inflammation and Oncogenic Signal Transduction by Helicobacter pylori

Helicobacter pylori exemplifies one of the most favourable bacterial pathogens worldwide. The bacterium colonizes the gastric mucosa in about half of the human population and constitutes a major risk factor for triggering gastric diseases such as stomach cancer. H. pylori infection represents a prime example of chronic inflammation and cancer-inducing bacterial pathogens. The microbe utilizes a remarkable set of virulence factors and strategies to control cellular checkpoints of inflammation and oncogenic signal transduction. This chapter emphasizes on the pathogenicity determinants of H. pylori such as the cytotoxin-associated genes pathogenicity island (cagPAI)-encoded type-IV secretion system (T4SS), effector protein CagA, lipopolysaccharide (LPS) metabolite ADP-glycero-β-D-manno-heptose (ADP-heptose), cytotoxin VacA, serine protease HtrA, and urease, and how they manipulate various key host cell signaling networks in the gastric epithelium. In particular, we highlight the H. pylori-induced disruption of cell-to-cell junctions, pro-inflammatory activities, as well as proliferative, pro-apoptotic and anti-apoptotic responses. Here we review these hijacked signal transduction events and their impact on gastric disease development.

The interaction of Helicobacter pylori with cancer immunomodulatory stromal cells: New insight into gastric cancer pathogenesis

Gastric cancer is the fourth most common cause of cancer-linked deaths in the world. Gastric tumor cells have biological characteristics such as rapid proliferation, high invasiveness, and drug resistance, which result in recurrence and poor survival. Helicobacter pylori (H. pylori) has been proposed as a first-class carcinogen for gastric cancer according to the 1994 world health organization (WHO) classification. One of the important mechanisms by which H. pylori affects the gastric environment and promotes carcinogenesis is triggering inflammation. H. pylori induces an inflammatory response and a plethora of different signal transduction processes, leading to gastric mucosal disturbance, chronic gastritis, and a multi-step complex pathway that initiates carcinogenesis. It seems undeniable that the interaction between various cell types, including immune cells, gastric epithelium, glands, and stem cells, is vital for the progression and development of carcinogenesis concerning H. pylori. The interactions of H. pylori with surrounding cells play a key role in cancer progression. In this review, we discuss the interplay between H. pylori and tumor-supportive cells, including mesenchymal stem cells (MSCs), cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), and myeloid derived-suppressor cells (MDSCs) in gastric cancer. It is hoped that clarifying the specific mechanisms for 'cross-talk' between H. pylori and these cells will provide promising strategies for developing new treatments.

Genotyping Helicobacter pylori and fgf7 gene expression in gastric cancer

BACKGROUND

Helicobacter pylori as the causative agent of the most common chronic bacterial infectious disease in human still involves a range of clinical challenging complications. In this meantime, the survey of the interaction between H. pylori virulence genes expression and its consequences on gastric antral epithelial cells is Controversial. This study surveyed the correlations between H. pylori cag Pathogenicity Island and virulence factors genes with Fgf7 gene expression as an angiogenic factor in developing gastric cancer in gastric antral epithelial cells of patients with H. pylori infection.

METHOD

Gastric antral biopsy samples collected from patients out of exclusion criteria, including consumption of tobacco, alchohol and anti-H. pylori drugs, were categorized into gastric cancer (case group n:53) and gastritis (control group n:50) with and without H. pylori infection to detect changes in cDNA of fgf7 in gastric antral epithelial cells by using Real Time RT PCR. Extracted total RNA from gastric antral biopsy samples was used to synthesize cDNA for real time PCR. Furthermore, the cDNA of H. pylori cag Pathogenicity Island and other virulence factors genes were detected by using specific designed primers and simple PCR.

RESULTS

Fgf7 gene expression revealed a significantly increase in gastric antral epithelial cells of gastric cancer and H. pylori-positive patients in contrast with gastritis and H. pylori-negative patients (p < 0.05). In the meanwhile, cag Pathogenicity Island and hopQ genotypes showed a positive correlation with Fgf7 gene expression (fold changes of cDNA) in gastric antral epithelial cells (p < 0.05).

CONCLUSION

This study revealed an obvious correlation between Fgf7 gene expression in gastric antral epithelial cells of patients with H. pylori carcinogenic genotypes infection and some host factors including age.

Helicobacter pylori infection induces stem cell-like properties in Correa cascade of gastric cancer

Gastric cancer (GC) is the fourth leading cause of cancer-related death. Its poor prognosis is attributed to unclear pathogenesis. Currently, the most widely accepted model for elucidating the mechanism of GC is the Correa cascade, which covers several histological lesions of the gastric mucosa. GC stem cells (CSCs) are crucial for oncogenesis in the Correa cascade and GC progression. As Helicobacter pylori (H. pylori) is the etiological factor in the Correa cascade, growing evidence suggests that enhancement of gastric stem cell-like properties and increase in CSCs correlate with H. pylori infection. In this paper, we review recent studies that present pathogenic mechanisms by which H. pylori induces gastric stem cell-like properties and CSCs, which may supplement the existing Correa model of GC. First, the dysfunction of developmental signaling pathways associated with H. pylori infection leads to the enhancement of gastric stemness. Second, H. pylori infection promotes alteration of the gastric mucosal microenvironment. In addition, epithelial-mesenchymal transition (EMT) may contribute to H. pylori-induced gastric stemness. Taken together, understanding these pathogeneses will provide potential therapeutic targets for the treatment of CSCs and malignant GC in H. pylori induced-Correa cascade of GC.

Epithelial-to-mesenchymal transition hinders interferon-γ-dependent immunosurveillance in lung cancer cells

The epithelial-to-mesenchymal transition (EMT) is involved in cancer metastasis; nevertheless, interferon (IFN)-γ induces anticancer activities by causing cell growth suppression, cytotoxicity, and migration inhibition. Regarding the poor response to exogenously administered IFN-γ as anticancer therapy, it was hypothesized that malignant cells may acquire a means of escaping from IFN-γ immunosurveillance, likely through an EMT-related process. A genomic analysis of human lung cancers revealed a negative link between the EMT and IFN-γ signaling, while compared to human lung adenocarcinoma A549 cells, IFN-γ-hyporesponsive AS2 cells exhibited mesenchymal characteristics. Chemically, physically, and genetically engineered EMT attenuated IFN-γ-induced IFN regulatory factor 1 transactivation. Poststimulation of transforming growth factor-β induced the EMT and also selectively retarded IFN-γ-responsive gene expression as well as IFN-γ-induced signal transducer and activator of transcription 1 activation, major histocompatibility complex I, and CD54 expression, cell migration/invasion inhibition, and direct/indirect cytotoxicity. Without changes in IFN-γ receptors, excessive oxidative activation of Src homology-2 containing phosphatase 2 (SHP2) in cells undergoing the EMT primarily caused cellular hyporesponsiveness to IFN-γ signaling and cytotoxicity, while combining an SHP2 inhibitor or antioxidant sensitized EMT-associated AS2 and mesenchymal A549 cells to IFN-γ-induced priming effects on tumor necrosis factor-related apoptosis-inducing ligand cytotoxicity. In cell line-derived xenograft models, combined treatment with IFN-γ and an SHP2 inhibitor induced enhanced anticancer activities. These results imply that EMT-associated SHP2 activation inhibits IFN-γ signaling, facilitating lung cancer cell escape from IFN-γ immunosurveillance.

Association between serum vitamin D levels and Helicobacter pylori cytotoxic-associated gene A seropositivity: a cross-sectional study in US adults from NHANES III

OBJECTIVE

To assess the association of serum vitamin D (VD) levels and Helicobacter pylori (H. pylori) cytotoxic-associated gene A (CagA) seropositivity, and further explore potential effect modifiers in this association.

DESIGN

Cross-sectional study.

SETTING

Data from phase I of the National Health and Nutrition Examination Survey (NHANES III, 1988-1991) led by the Center for Disease Control and Prevention.

PARTICIPANTS

A total of 3512 US adults (≥20 years) with both serum VD levels and H. pylori CagA antibody data from NHANES III were included in the analysis.

METHODS

VD deficiency was defined as serum 25(OH)D concentrations<20 ng/mL. Logistic regression models were used to assess the association of serum VD levels and H. pylori CagA seropositivity (VD-Hp CagA+), and stratification analyses were used to explore potential effect modifiers.

RESULTS

There was no significant association of VD-Hp CagA+ in the general population. But serum 25(OH)D concentrations were associated with H. pylori CagA+ in non-Hispanic whites (adjusted OR=1.02, 95% CI: 1.00 to 1.03), other races/ethnicities (adjusted OR=1.08, 95% CI: 1.01 to 1.06), populations born in other countries (adjusted OR=1.09, 95% CI: 1.04 to 1.15) or occasional drinkers (adjusted OR=0.93, 95% CI: 0.88 to 0.99). VD deficiency was associated with H. pylori CagA+ in non-Hispanic whites (adjusted OR=0.69, 95% CI: 0.53 to 0.92), populations born in other countries (adjusted OR=0.47, 95% CI: 0.25 to 0.89), non-drinkers (adjusted OR=0.80, 95% CI: 0.65 to 0.99), occasional drinkers (adjusted OR=2.53, 95% CI: 1.06 to 6.05), population with first quartile level of serum ferritin (adjusted OR=0.70, 95% CI: 0.51 to 0.96) or fourth quartile level of serum folate (adjusted OR=0.63, 95% CI: 0.46 to 0.87).

CONCLUSIONS

Racial/ethnic differences and different serum ferritin or serum folate levels may be effect modifiers for the association of VD-Hp CagA+.

Matrix Metalloproteinases in Helicobacter pylori-Associated Gastritis and Gastric Cancer

Gastric cancer is one of the leading causes of the cancer-related mortality worldwide. The etiology of this disease is complex and involves genetic predisposition and environmental factors, including Helicobacter pylori. Infection of the stomach with H. pylori leads to gastritis and gastric atrophy, which can progress stepwise to gastric cancer. Matrix metalloproteinases (MMPs) actively participate in the pathology development. The further progression of gastric cancer seems to be less dependent on bacteria but of intra-tumor cell dynamics. Bioinformatics data confirmed an important role of the extracellular matrix constituents and specific MMPs in stomach carcinoma invasion and metastasis, and revised their potential as predictors of the disease outcome. In this review, we describe, in detail, the impact of MMPs in H. pylori-associated gastritis and gastric cancer.

Helicobacter pylori cagA status and gastric mucosa-associated lymphoid tissue lymphoma: a systematic review and meta-analysis

Background

Recent studies have investigated the role of Helicobacter pylori infection in the development of gastric mucosa-associated lymphoid tissue (MALT) lymphoma. It is estimated that approximately 0.1% of people infected with H. pylori develop gastric MALT lymphoma. However, the role of the CagA antigen, the highest causative agent of H. pylori, in increasing the risk of gastric MALT lymphoma remains unclear and controversial. A systematic review and meta-analysis were conducted to evaluate the effect of cagA status on the development of gastric MALT lymphoma.

Methods

All articles evaluating the status of the cagA gene in the development of gastric MALT lymphoma were collected using systematic searches in online databases, including PubMed, Scopus, Embase, and Google Scholar, regardless of publication date. The association between cagA and gastric MALT lymphoma was assessed using the odds ratio (OR) summary. In addition, a random-effects model was used in cases with significant heterogeneity.

Results

A total of 10 studies met our inclusion criteria, among which 1860 patients participated. No association between cagA status and the development of MALT lymphoma (extranodal marginal zone B-cell lymphoma) was found in this study (OR 1.30; 0.906–1.866 with 95% CIs; I²: 45.83; Q-value: 12.92). Surprisingly, a meaningful association was observed between cagA status and diffuse large B-cell lymphoma (OR 6.43; 2.45–16.84 with 95% CIs). We also observed an inverse association between vacA and gastric MALT lymphoma risk (OR 0.92; 0.57–1.50 with 95% CIs).

Conclusions

It seems that the infection with cagA-positive H. pylori strains does not have a meaningful effect on the gastric MALT lymphoma formation, while translocated CagA antigen into the B cells plays a crucial role in the development of diffuse large B-cell lymphoma.

Elucidated tumorigenic role of MAML1 and TWIST1 in gastric cancer is associated with Helicobacter pylori infection

BACKGROUND

Epithelial-mesenchymal transition (EMT) has a fundamental role in tumor initiation, progression, and metastasis. Helicobacter pylori (HP) induces EMT and thus causes gastric cancer (GC) by deregulating multiple signaling pathways involved in EMT. TWIST1 and MAML1 have been confirmed to be critical inducers of EMT via diverse signaling pathways such as Notch signaling. This study aimed to investigate for the first time possible associations between TWIST1/MAML1 mRNA expression levels, HP infection, and clinicopathological characteristics in GC patients.

METHOD

TWIST1 and MAML1 mRNA expression levels were evaluated in tumoral and adjacent normal tissues in 73 GC patients using the quantitative reverse transcription PCR (RT-qPCR) method. PCR technique was also applied to examine the infection with HP in GC samples.

RESULTS

Upregulation of TWIST1 and MAML1 expression was observed in 35 (48%) and 34 (46.6%) of 73 tumor samples, respectively. Co-overexpression of these genes was found in 26 of 73 (35.6%) tumor samples; meanwhile, there was a significant positive correlation between MAML1 and TWIST1 mRNA expression levels (P < 0.001). MAML1 overexpression exhibited meaningful associations with advanced tumor stages (P = 0.006) and nodal metastases (P ˂ 0.001). 34 of 73 (46.6%) tumors tested positive for HP, and meanwhile, MAML1 expression was positively related with T (P = 0.05) and grade (P = 0.0001) in these HP-positive samples. Increased TWIST1 expression was correlated with patient sex (P = 0.035) and advanced tumor grade (P = 0.017) in HP-infected tumors. Furthermore, TWIST1 and MAML1 expression levels were inversely linked with histologic grade in HP-negative tumor samples (P = 0.021 and P = 0.048, respectively).

CONCLUSION

We propose TWIST1 and MAML1 as potential biomarkers of advanced-stage GC that determine the characteristics and aggressiveness of the disease. Based on accumulating evidence and our findings, they can be introduced as promising therapeutic targets to modify functional abnormalities in cells that promote GC progression. Moreover, HP may enhance GC growth and metastasis by disrupting TWIS1/MAML1 expression patterns and related pathways.

Helicobacter pylori in gastric cancer: Features of infection and their correlations with long-term results of treatment

BACKGROUND

Helicobacter pylori (H. pylori) is a spiral-shaped bacterium responsible for the development of chronic gastritis, gastric ulcer, gastric cancer (GC), and MALT-lymphoma of the stomach. H. pylori can be present in the gastric mucosa (GM) in both spiral and coccoid forms. However, it is not known whether the severity of GM contamination by various vegetative forms of H. pylori is associated with clinical and morphological characteristics and long-term results of GC treatment.

AIM

To establish the features of H. pylori infection in patients with GC and their correlations with clinical and morphological characteristics of diseases and long-term results of treatment.

METHODS

Of 109 patients with GC were included in a prospective cohort study. H. pylori in the GM and tumor was determined by rapid urease test and by immunohistochemically using the antibody to H. pylori. The results obtained were compared with the clinical and morphological characteristics and prognosis of GC. Statistical analysis was performed using the Statistica 10.0 software.

RESULTS

H. pylori was detected in the adjacent to the tumor GM in 84.5% of cases, of which a high degree of contamination was noted in 50.4% of the samples. Coccoid forms of H. pylori were detected in 93.4% of infected patients, and only coccoid-in 68.9%. It was found that a high degree of GM contamination by the coccoid forms of H. pylori was observed significantly more often in diffuse type of GC (P = 0.024), in poorly differentiated GC (P = 0.011), in stage T3-4 (P = 0.04) and in N1 (P = 0.011). In cases of moderate and marked concentrations of H. pylori in GM, a decrease in 10-year relapse free and overall survival from 55.6% to 26.3% was observed (P = 0.02 and P = 0.07, respectively). The relationship between the severity of the GM contamination by the spiral-shaped forms of H. pylori and the clinical and morphological characteristics and prognosis of GC was not revealed.

CONCLUSION

The data obtained indicates that H. pylori may be associated not only with induction but also with the progression of GC.

Emerging therapeutic targets for gastric cancer from a host-Helicobacter pylori interaction perspective

INTRODUCTION

Gastric cancer (GC) has the higher genetic, cytologic, and architectural heterogeneity compared to other gastrointestinal cancers. By inducing gastric inflammation, Helicobacter pylori (HP) may lead to GC through combining bacterial factors with host factors. In this regard, identification of the major therapeutic targets against the host-HP interactions plays a critical role in GC prevention, diagnosis, and treatment.

AREAS COVERED

This study offers new insights into the promising therapeutic targets against the angiogenesis, invasion, or metastasis of GC from a host-HP interaction perspective. To this end, MEDLINE, EMBASE, LILACS, AIM, and IndMed databases were searched for relevant articles since 1992.

EXPERT OPINION

Wnt signaling and COX pathway have a well-documented history in the genesis of GC by HP and might be considered as the most promising targets for early GC treatment. Destroying HP may decrease the risk of GC, but it cannot fully hinder the GC development induced by HP infection. Therefore, targeting HP-activated pathways, especially COX-2/Wnt/beta-catenin/VEGF, TLR2/TLR9/COX-2, COX2-PGE2, and NF-κB/COX-2, as well as EPHA2, MMPs, and miR-543/SIRT1 axis, can be an effective measure in the early treatment of GC. However, different clinical trials and large, multi-center cohorts are required to validate these potentially effective targets for GC therapy.

Helicobacter Pylori Variants with ABC-Type Tyrosine Phosphorylation Motif in Gastric Biopsies of Ghanaian Patients

BACKGROUND

Helicobacter pylori pathogenicity and disease severity are determined by the tyrosine phosphorylation motifs of CagA protein. This study is aimed at detecting the presence of H. pylori and identifying the CagA tyrosine phosphorylation motifs in Ghanaian patients. Material and Methods. A total of 94 archival genomic DNA samples from gastric biopsies were used for the study, and H. pylori was detected by amplifying the 16S rRNA gene. The 3'-end variable region of the cagA gene was amplified, and the entire 3'-end was sequenced and translated into amino acids.

RESULTS

H. pylori was detected in 53.2% (50/94) of the samples, and all the detected bacteria harboured the cagA gene. Two variants of the bacteria were identified based on the size of the amplified cagA gene: 207 bp and 285 bp. The 207 bp and 285 bp variants accounted for 74% and 22%, respectively, and 4% showed both fragments. Translated amino acid sequence of the cagA gene showed EPIYA-A, EPIYA-B, and EPIYA-C (ABC type) motifs, indicating the Western variant. The CagA protein C-terminal showed insertion of amino acids in the sequence flanking the EPIYA-A motif at the N-terminal and a complete deletion of the EPIYA-CC and EPIYA-CCC motifs together with the flanking sequences.

CONCLUSIONS

H. pylori identified were Western variant (ABC type) with unique amino acid insertions, suggesting unique variants in Ghanaian patients. Further investigation is however required to understand the role of the molecular diversity of the variant in gastric disease outcome.

The novel ZEB1-upregulated protein PRTG induced by Helicobacter pylori infection promotes gastric carcinogenesis through the cGMP/PKG signaling pathway

Helicobacter pylori (H. pylori) is listed as a class I carcinogen in human gastric cancer; however, the underlying mechanisms are poorly understood. In this study, we identified Protogenin (PRTG) was upregulated in both gastric cancer tissues and H. pylori-infected tissues by analyzing dysregulated genes in TCGA and GEO databases. Importantly, upregulated PRTG predicted poor prognosis of gastric cancer patients and integrative analysis revealed that PRTG served as an oncogenic protein in gastric cancer and was required for H. pylori-mediated tumorigenic activities in in vitro cellular and in vivo tumor-bearing mouse models. Mechanistically, H. pylori infection enhanced PRTG expression by promoting transcriptional factor ZEB1 stabilization and recruitment to the PRTG promoter, and which then activated the sub-following cGMP/PKG signaling pathway in bioinformatic and cellular studies. Cellular studies further confirmed that PRTG depended on activating cGMP/PKG axis to promote proliferation, metastasis, and chemoresistance of gastric cancer cells. The PKG inhibitor KT5823 played synergistic anti-tumor effects with cisplatin and paclitaxel to gastric cancer cells in in vitro cellular and in vivo tumor-bearing mouse models. Taken together, our findings suggested that H. pylori infection depends on ZEB1 to induce PRTG upregulation, and which leading to the development and progression of gastric cancer through activating cGMP/PKG signaling pathway. Blocking PRTG/cGMP/PKG axis, therefore, presents a promising novel therapeutic strategy for gastric cancer.

Precision Medicine Approaches to Prevent Gastric Cancer

Gastric cancer remains one of the most common causes of cancer-related death worldwide, although the incidence is declining gradually. The primary risk factor for gastric cancer is Helicobacter pylori infection. The Kyoto global consensus report recommends eradication of H. pylori in all infected patients. However, because it is difficult to stratify the risk of carcinogenesis among patients with a history of H. pylori infection, annual endoscopic surveillance is performed for everyone after eradication. This review summarizes the current approaches used to screen for novel molecules that could assist in the diagnosis of gastric cancer and reduce mortality. Most well-studied molecules are tissue protein biomarkers expressed by the gastric epithelium and associated with metaplasia-dysplasia-carcinoma sequences. Other strategies focus on the origin of cancer stem cell-related markers, such as CD44, and immune reaction-related markers, such as matrix metallopeptidases. Noninvasive methods such as blood-based approaches are more attractive. Serum pepsinogen levels predict the severity of gastric mucosal atrophy before H. pylori eradication, whereas plasma ghrelin levels are associated with atrophy even after eradication. Cell-free DNAs and RNAs are attractive tools for the early detection of cancer. These ideas could lead to the development of more personalized strategies for cancer prevention based on cutting-edge technologies.

Impact of Helicobacter pylori Infection and Its Major Virulence Factor CagA on DNA Damage Repair

Helicobacter pylori infection induces a plethora of DNA damages. Gastric epithelial cells, in order to maintain genomic integrity, require an integrous DNA damage repair (DDR) machinery, which, however, is reported to be modulated by the infection. CagA is a major H. pylori virulence factor, associated with increased risk for gastric carcinogenesis. Its pathogenic activity is partly regulated by phosphorylation on EPIYA motifs. Our aim was to identify effects of H. pylori infection and CagA on DDR, investigating the transcriptome of AGS cells, infected with wild-type, ΔCagA and EPIYA-phosphorylation-defective strains. Upon RNA-Seq-based transcriptomic analysis, we observed that a notable number of DDR genes were found deregulated during the infection, potentially resulting to base excision repair and mismatch repair compromise and an intricate deregulation of nucleotide excision repair, homologous recombination and non-homologous end-joining. Transcriptome observations were further investigated on the protein expression level, utilizing infections of AGS and GES-1 cells. We observed that CagA contributed to the downregulation of Nth Like DNA Glycosylase 1 (NTHL1), MutY DNA Glycosylase (MUTYH), Flap Structure-Specific Endonuclease 1 (FEN1), RAD51 Recombinase, DNA Polymerase Delta Catalytic Subunit (POLD1), and DNA Ligase 1 (LIG1) and, contrary to transcriptome results, Apurinic/Apyrimidinic Endodeoxyribonuclease 1 (APE1) upregulation. Our study accentuates the role of CagA as a significant contributor of H. pylori infection-mediated DDR modulation, potentially disrupting the balance between DNA damage and repair, thus favoring genomic instability and carcinogenesis.

Gut Microbiota and Colon Cancer: A Role for Bacterial Protein Toxins?

Accumulating evidence indicates that the human intestinal microbiota can contribute to the etiology of colorectal cancer. Triggering factors, including inflammation and bacterial infections, may favor the shift of the gut microbiota from a mutualistic to a pro-carcinogenic configuration. In this context, certain bacterial pathogens can exert a pro-tumoral activity by producing enzymatically-active protein toxins that either directly induce host cell DNA damage or interfere with essential host cell signaling pathways involved in cell proliferation, apoptosis, and inflammation. This review is focused on those toxins that, by mimicking carcinogens and cancer promoters, could represent a paradigm for bacterially induced carcinogenesis.

Mechanisms of the Epithelial-Mesenchymal Transition and Tumor Microenvironment in Helicobacter pylori-Induced Gastric Cancer

Helicobacter pylori (H. pylori) is one of the most common human pathogens, affecting half of the world’s population. Approximately 20% of the infected patients develop gastric ulcers or neoplastic changes in the gastric stroma. An infection also leads to the progression of epithelial–mesenchymal transition within gastric tissue, increasing the probability of gastric cancer development. This paper aims to review the role of H. pylori and its virulence factors in epithelial–mesenchymal transition associated with malignant transformation within the gastric stroma. The reviewed factors included: CagA (cytotoxin-associated gene A) along with induction of cancer stem-cell properties and interaction with YAP (Yes-associated protein pathway), tumor necrosis factor α-inducing protein, Lpp20 lipoprotein, Afadin protein, penicillin-binding protein 1A, microRNA-29a-3p, programmed cell death protein 4, lysosomal-associated protein transmembrane 4β, cancer-associated fibroblasts, heparin-binding epidermal growth factor (HB-EGF), matrix metalloproteinase-7 (MMP-7), and cancer stem cells (CSCs). The review summarizes the most recent findings, providing insight into potential molecular targets and new treatment strategies for gastric cancer.

HP-CagA+ Regulates the Expression of CDK4/CyclinD1 via reg3 to Change Cell Cycle and Promote Cell Proliferation

Previous studies have shown that regeneration gene 3 (reg3) is significantly expressed in gastric mucosa tissues with Helicobacter pylori (HP) cytotoxin-associated gene A (CagA)-positive (HP-CagA+). CagA-positive HP increases the risk of gastric cancer. The purpose of this study was to investigate the correlation between reg3 and HP-CagA+ and explore the effects of reg3 on the proliferation of gastric cancer cells and the development of tissues and organs. We analyzed the expression of reg3 in human tissues and organs. The results showed that reg3 expression in gastric tissues was significantly higher than that in other tissues and organs. In addition, reg3 influenced the prognosis of gastric, lung, and ovarian cancers. Immunohistochemical analysis indicated that the expression of reg3 and CagA in cancerous tissues was higher than that in adjacent tissues. HP-CagA⁺ infection of gastric cancer cells promotes reg3 expression, suggesting that reg3 may be a target gene of CagA in gastric cancer, which together affects the formation and development of gastric cancer. reg3 and CagA promote cell proliferation, and then affect the development of mouse tissues and organs by regulating G1/S phase transition of the cell cycle via the formation of the cell cycle-dependent complex CDK4/CyclinD1. This is the first study that shows the influence of CagA on the cell cycle and induction of cell proliferation by promoting reg3 expression.

Activity and Functional Importance of Helicobacter pylori Virulence Factors

Helicobacter pylori is a very successful Gram-negative pathogen colonizing the stomach of humans worldwide. Infections with this bacterium can generate pathologies ranging from chronic gastritis and peptic ulceration to gastric cancer. The best characterized H. pylori virulence factors that cause direct cell damage include an effector protein encoded by the cytotoxin-associated gene A (CagA), a type IV secretion system (T4SS) encoded in the cag-pathogenicity island (cag PAI), vacuolating cytotoxin A (VacA), γ-glutamyl transpeptidase (GGT), high temperature requirement A (HtrA, a serine protease) and cholesterol glycosyl-transferase (CGT). Since these H. pylori factors are either surface-exposed, secreted or translocated, they can directly interact with host cell molecules and are able to hijack cellular functions. Studies on these bacterial factors have progressed substantially in recent years. Here, we review the current status in the characterization of signaling cascades by these factors in vivo and in vitro, which comprise the disruption of cell-to-cell junctions, induction of membrane rearrangements, cytoskeletal dynamics, proliferative, pro-inflammatory, as well as, pro-apoptotic and anti-apoptotic responses or immune evasion. The impact of these signal transduction modules in the pathogenesis of H. pylori infections is discussed.

The Cancer Microbiota: EMT and Inflammation as Shared Molecular Mechanisms Associated with Plasticity and Progression

With the advent of novel molecular platforms for high-throughput/next-generation sequencing, the communities of commensal and pathogenic microorganisms that inhabit the human body have been defined in depth. In the last decade, the role of microbiota-host interactions in driving human cancer plasticity and malignant progression has been well documented. Germ-free preclinical models provided an invaluable tool to demonstrate that the human microbiota can confer susceptibility to various types of cancer and can also modulate the host response to therapeutic treatments. Of interest, besides the detrimental effects of dysbiosis on cancer etiopathogenesis, specific microorganisms have been shown to exert protective activities against cancer growth. This has strong clinical implications, as restoration of the physiologic microbiota is being rapidly implemented as a novel anticancer therapeutic strategy. Here, we reviewed past and recent literature depicting the role of microbiota-host interactions in modulating key molecular mechanisms that drive human cancer plasticity and lead to malignant progression. We analyzed microbiota-host interactions occurring in the gut as well as in other anatomic sites, such as oral and nasal cavities, lungs, breast, esophagus, stomach, reproductive tract, and skin. We revealed a common ground of biological alterations and pathways modulated by a dysbiotic microbiota and potentially involved in the control of cancer progression. The molecular mechanisms most frequently affected by the pathogenic microorganisms to induce malignant progression involve epithelial-mesenchymal transition- (EMT-) dependent barrier alterations and tumor-promoting inflammation. This evidence may pave the way to better stratify high-risk cancer patients based on unique microenvironmental/microbial signatures and to develop novel, personalized, biological therapies.

Helicobacter pylori infection and gastric cancer biology: tempering a double-edged sword

Helicobacter pylori (H. pylori) infection affects an estimated 4.4 billion people globally. Moreover, H. pylori presents the most significant risk factor for gastric cancer and low-grade mucosa-associated lymphoid tissue (MALT) lymphoma, and it is the first example of bacterial infection linked to carcinogenesis. Here, we contend that H. pylori research, which focuses on a cancer-causing pathogen resident in a relatively accessible organ, the stomach, could constitute an exemplar for microbial-related carcinogenesis in less tractable organs, such as the pancreas and lung. In this context, molecular biological approaches that could reap rewards are reviewed, including: (1) gastric cancer dynamics, particularly the role of stem cells and the heterogeneity of neoplastic cells, which are currently being investigated at the single-cell sequencing level; (2) mechanobiology, and the role of three-dimensional organoids and matrix metalloproteases; and (3) the connection between H. pylori and host pathophysiology and the gut microbiome. In the context of H. pylori's contribution to gastric cancer, several important conundrums remain to be fully elucidated. From among them, this article discusses (1) why H. pylori infection, which causes both gastric and duodenal inflammation, is only linked to gastric cancer; (2) whether a "precision oncomicrobiology" approach could enable a fine-tuning of the expression of only cancer-implicated H. pylori genes while maintaining beneficial H. pylori-mediated factors in extra-gastric tissues; and (3) the feasibility of using antibiotics targeting the microbial DNA damage system, which shares commonalities with mechanisms for human cell replication, as chemopreventives. Additional therapeutic perspectives are also discussed.

Virulence factor genotyping of Helicobacter pylori isolated from Costa Rican dyspeptic patients

BACKGROUND AND AIMS

Costa Rica is one of the countries with the highest incidence and mortality rates for gastric cancer. Helicobacter pylori infection rates are high in the whole country. We have previously shown that H. pylori CagA+ is significantly associated with atrophic gastritis (AG) of the antrum in a dyspeptic population. The aim of this work is to determine if other H. pylori virulence factors (vacA, dupA, oipA, iceA and babA2) are associated with atrophic gastritis (AG) or duodenal ulcer (DU).

METHODS

The presence of virulence genes in Costa Rican H. pylori isolates was analyzed by PCR in 151 cultured strains from patients with dyspeptic symptoms. Endoscopic and histopathological diagnoses were available. Odds-ratio and 95% confidence intervals for AG patients vs. non-atrophic gastritis (NAG) or DU patients vs. no duodenal ulcer (NDU) patients were calculated.

RESULTS

Amongst the studied isolates, 82% had the cagA⁺, 76.2% had the vacA s1m1, 97.0% had the oipA⁺, 21.0% had the icea1, 79.0% had the iceA2, 44.0% had the babA2⁺ and 76.0% the dupA⁺ genotypes. Infection with H pylori cagA⁺, dupA⁺, oipA⁺, iceA, babA2⁺, and vacA s1m1 genotypes was not associated with AG risk. The frequency of the dupA gene was 78.7 and 60.9% in isolates from patients with NDU and DU, respectively, and its presence was significantly associated with decreased risk of duodenal ulcer [odds-ratio: 0.33, p = 0.024, confidence interval 95% (0.11-0.85)].

CONCLUSION

H. pylori dupA genotype is inversely associated with DU risk in this population.

Priming the seed: Helicobacter pylori alters epithelial cell invasiveness in early gastric carcinogenesis

Helicobacter pylori (H. pylori) infection is a well-established risk factor for the development of gastric cancer (GC), one of the most common and deadliest neoplasms worldwide. H. pylori infection induces chronic inflammation in the gastric mucosa that, in the absence of treatment, may progress through a series of steps to GC. GC is only one of several clinical outcomes associated with this bacterial infection, which may be at least partially attributed to the high genetic variability of H. pylori. The biological mechanisms underlying how and under what circumstances H. pylori alters normal physiological processes remain enigmatic. A key aspect of carcinogenesis is the acquisition of traits that equip preneoplastic cells with the ability to invade. Accumulating evidence implicates H. pylori in the manipulation of cellular and molecular programs that are crucial for conferring cells with invasive capabilities. We present here an overview of the main findings about the involvement of H. pylori in the acquisition of cell invasive behavior, specifically focusing on the epithelial-to-mesenchymal transition, changes in cell polarity, and deregulation of molecules that control extracellular matrix remodeling.

Group B streptococcus exploits vaginal epithelial exfoliation for ascending infection

Thirteen percent of pregnancies result in preterm birth or stillbirth, accounting for fifteen million preterm births and three and a half million deaths annually. A significant cause of these adverse pregnancy outcomes is in utero infection by vaginal microorganisms. To establish an in utero infection, vaginal microbes enter the uterus by ascending infection; however, the mechanisms by which this occurs are unknown. Using both in vitro and murine models of vaginal colonization and ascending infection, we demonstrate how a vaginal microbe, group B streptococcus (GBS), which is frequently associated with adverse pregnancy outcomes, uses vaginal exfoliation for ascending infection. GBS induces vaginal epithelial exfoliation by activation of integrin and β-catenin signaling. However, exfoliation did not diminish GBS vaginal colonization as reported for other vaginal microbes. Rather, vaginal exfoliation increased bacterial dissemination and ascending GBS infection, and abrogation of exfoliation reduced ascending infection and improved pregnancy outcomes. Thus, for some vaginal bacteria, exfoliation promotes ascending infection rather than preventing colonization. Our study provides insight into mechanisms of ascending infection by vaginal microbes.

Involvement of microRNAs-MMPs-E-cadherin in the migration and invasion of gastric cancer cells infected with Helicobacter pylori

It has been found that Helicobacter pylori （H. pylori）is not only the main cause of gastric cancer, but also closely related to its metastasis. E-cadherin cleavage induced by matrix metalloproteinases (MMPs) plays an important role in the tumor metastasis. In the present study, we investigated the role of microRNAs-MMPs-E-cadherin in migration and invasion of gastric cancer cells treated with H. pylori. The results showed that H. pylori induced migration and invasion of SGC-7901 cells with a down-regulation of E-cadherin expression, which were abolished by MMPs knock down, E-cadherin overexpression, mimics of miR128 and miR148a. MiR128/miR148a inhibitors restored MMP-3/MMP-7 expression, down-regulated E-cadherin level, and accelerated cellular migration and invasion. This study suggests that H. pylori induces migration and invasion of gastric cancer cells through reduction of E-cadherin function by activation of MMP-3, - 7. The present results also suggest that the activated MMPs/E-cadherin pathway is related with down-regulation of miR128/miR148a in the human gastric cancer cells infected with H. pylori.

Creation and Initial Characterization of Isogenic Helicobacter pylori CagA EPIYA Variants Reveals Differential Activation of Host Cell Signaling Pathways

The polymorphic CagA toxin is associated with Helicobacter pylori-induced disease. Previous data generated using non-isogenic strains and transfection models suggest that variation surrounding the C-terminal Glu-Pro-Ile-Tyr-Ala (EPIYA) motifs as well as the number of EPIYA motifs influence disease outcome. To investigate potential CagA-mediated effects on host cell signaling, we constructed and characterized a large panel of isogenic H. pylori strains that differ primarily in the CagA EPIYA region. The number of EPIYA-C motifs or the presence of an EPIYA-D motif impacted early changes in host cell elongation; however, the degree of elongation was comparable across all strains at later time points. In contrast, the strain carrying the EPIYA-D motif induced more IL-8 secretion than any other EPIYA type, and a single EPIYA-C motif induced comparable IL-8 secretion as isolates carrying multiple EPIYA-C alleles. Similar levels of ERK1/2 activation were induced by all strains carrying a functional CagA allele. Together, our data suggest that polymorphism in the CagA C-terminus is responsible for differential alterations in some, but not all, host cell signaling pathways. Notably, our results differ from non-isogenic strain studies, thus highlighting the importance of using isogenic strains to study the role of CagA toxin polymorphism in gastric cancer development.

Membrane-bound β-catenin degradation is enhanced by ETS2-mediated Siah1 induction in Helicobacter pylori-infected gastric cancer cells

β-catenin has two different cellular functions: intercellular adhesion and transcriptional activity. The E3 ubiquitin ligase Siah1 causes ubiquitin-mediated degradation of the cytosolic β-catenin and therefore, impairs nuclear translocation and oncogenic function of β-catenin. However, the effect of Siah1 on the cell membrane bound β-catenin has not been studied. In this study, we identified that the carcinogenic bacterium H. pylori increased ETS2 transcription factor-mediated Siah1 protein expression in gastric cancer cells (GCCs) MKN45, AGS and Kato III. Siah1 protein level was also noticeably higher in gastric adenocarcinoma biopsy samples as compared to non-cancerous gastric epithelia. Siah1 knockdown significantly decreased invasiveness and migration of H. pylori-infected GCCs. Although, Siah1 could not increase degradation of the cytosolic β-catenin and its nuclear translocation, it enhanced degradation of the membrane-bound β-catenin in the infected GCCs. This loss of membrane-bound pool of β-catenin was not associated with the proteasomal degradation of E-cadherin. Thus, this work delineated the role of Siah1 in increasing invasiveness of H. pylori-infected GCCs.

Proteolysis in Helicobacter pylori-Induced Gastric Cancer

Persistent infections with the human pathogen and class-I carcinogen Helicobacter pylori (H. pylori) are closely associated with the development of acute and chronic gastritis, ulceration, gastric adenocarcinoma and lymphoma of the mucosa-associated lymphoid tissue (MALT) system. Disruption and depolarization of the epithelium is a hallmark of H. pylori-associated disorders and requires extensive modulation of epithelial cell surface structures. Hence, the complex network of controlled proteolysis which facilitates tissue homeostasis in healthy individuals is deregulated and crucially contributes to the induction and progression of gastric cancer through processing of extracellular matrix (ECM) proteins, cell surface receptors, membrane-bound cytokines, and lateral adhesion molecules. Here, we summarize the recent reports on mechanisms how H. pylori utilizes a variety of extracellular proteases, involving the proteases Hp0169 and high temperature requirement A (HtrA) of bacterial origin, and host matrix-metalloproteinases (MMPs), a disintegrin and metalloproteinases (ADAMs) and tissue inhibitors of metalloproteinases (TIMPs). H. pylori-regulated proteases represent predictive biomarkers and attractive targets for therapeutic interventions in gastric cancer.

In vitro culture and phenotypic and molecular characterization of gastric stem cells from human stomach

BACKGROUND

Human gastric mucosa shows continuous self-renewal via differentiation from stem cells that remain poorly characterized.

METHODS

We describe an original protocol for culture of gastric stem/progenitor cells from adult human stomach. The molecular characteristics of cells were studied using TaqMan low-density array and qRT-PCR analyses using the well-characterized H1 and H9 embryonic stem cells as reference. Epithelial progenitor cells were challenged with H. pylori to characterize their inflammatory response.

RESULTS

Resident gastric stem cells expressed specific molecular markers of embryonic stem cells (SOX2, NANOG, and OCT4), as well as others specific to adult stem cells, particularly LGR5 and CD44. We show that gastric stem cells spontaneously differentiate into epithelial progenitor cells that can be challenged with H. pylori. The epithelial progenitor response to H. pylori showed a cag pathogenicity island-dependent induction of matrix metalloproteinases 1 and 3, chemokine (CXCL1, CXCL5, CXCL8, CCL20) and interleukine 33 expression.

CONCLUSION

This study opens new outlooks for investigation of gastric stem cell biology and pathobiology as well as host-H. pylori interactions.

CDH1 (E-cadherin) expression independently affects clinical outcome in acute myeloid leukemia with normal cytogenetics

BACKGROUND

Epithelial-mesenchymal transition (EMT) is a critical process which involves in tumor metastasis. As an important EMT marker gene, CDH1 (E-cadherin) expression and its clinical implication in acute myeloid leukemia (AML) remain largely elusive.

METHODS

Real-time quantitative PCR (RQ-PCR) was carried out to examine CDH1 transcript level in 123 de novo AML patients and 34 controls.

RESULTS

Compared with controls, CDH1 was significantly downregulated in AML (p<0.001). The median level of CDH1 expression divided total AML patients into CDH1 low-expressed (CDH11ow) and CDH1 high-expressed (CDH1high) groups. There were no significant differences between the two groups in age, peripheral blood cell counts, complete remission (CR) rate, and the distribution of FAB/WHO subtypes as well as karyotypes/karyotypic classifications (p>0.05). However, CDH11ow group tended to have a higher bone marrow (BM) blasts (p=0.093). The spearman correlation analysis further illustrated a trend towards a negative correlation between CDH1 expression level and BM blasts (r=-0.214, p=0.052). CDH1low group had a tendency towards a lower frequency of N/K-RAS mutations (p=0.094). Furthermore, CDH1low patients had markedly shorter overall survival (OS) time in cytogenetic normal AML (CN-AML) (p=0.019). Both univariate and multivariate analyses confirmed the prognostic value of CDH1 expression in CN-AML patients (p=0.027 and 0.033, respectively).

CONCLUSIONS

CDH1 downregulation acted as an independent prognostic biomarker in CN-AML patients.

Microbial carcinogenic toxins and dietary anti-cancer protectants

Several toxins are known which account for the ability of some bacteria to initiate or promote carcinogenesis. These ideas are summarised and evidence is discussed for more specific mechanisms involving chymotrypsin and the bacterial chymotryptic enzyme subtilisin. Subtilisin and Bacillus subtilis are present in the gut and environment and both are used commercially in agriculture, livestock rearing and meat processing. The enzymes deplete cells of tumour suppressors such as deleted in colorectal cancer (DCC) and neogenin, so their potential presence in the food chain might represent an important link between diet and cancer. Over-eating increases secretion of chymotrypsin which is absorbed from the gut and could contribute to several forms of cancer linked to obesity. Inhibition of these serine proteases by Bowman–Birk inhibitors in fruit and vegetables could account for some of the protective effects of a plant-rich diet. These interactions represent previously unknown non-genetic mechanisms for the modification of tumour suppressor proteins and provide a plausible explanation contributing to both the pro-oncogenic effects of meat products and the protective activity of a plant-rich diet. The data suggest that changes to farming husbandry and food processing methods to remove these sources of extrinsic proteases might significantly reduce the incidence of several cancers.

Modification of Bacterial Effector Proteins Inside Eukaryotic Host Cells

Pathogenic bacteria manipulate their hosts by delivering a number of virulence proteins -called effectors- directly into the plant or animal cells. Recent findings have shown that such effectors can suffer covalent modifications inside the eukaryotic cells. Here, we summarize the recent reports where effector modifications by the eukaryotic machinery have been described. We restrict our focus on proteins secreted by the type III or type IV systems, excluding other bacterial toxins. We describe the known examples of effectors whose enzymatic activity is triggered by interaction with plant and animal cell factors, including GTPases, E2-Ubiquitin conjugates, cyclophilin and thioredoxins. We focus on the structural interactions with these factors and their influence on effector function. We also review the described examples of host-mediated post-translational effector modifications which are required for proper subcellular location and function. These host-specific covalent modifications include phosphorylation, ubiquitination, SUMOylation, and lipidations such as prenylation, fatty acylation and phospholipid binding.

Molecular mechanisms of gastric cancer initiation and progression by Helicobacter pylori

PURPOSE OF REVIEW

Infection with the Gram-negative, microaerophilic pathogen Helicobacter pylori results in gastric cancer in a subset of infected individuals. As such, H. pylori is the only WHO classified bacterial class I carcinogen. Numerous studies have identified mechanisms by which H. pylori alters host cell signaling pathways to cause disease. The purpose of this review is to highlight recent studies that explore mechanisms associated with induction of gastric cancer.

RECENT FINDINGS

Over the last year and a half, new mechanisms contributing to the etiology of H. pylori-associated gastric cancer development have been discovered. In addition to utilizing the oncogenic CagA toxin to alter host cell signaling pathways, H. pylori also induces host DNA damage and alters DNA methylation to perturb downstream signaling. Furthermore, H. pylori activates numerous host cell pathways and proteins that result in epithelial-to-mesenchymal transition and induction of cell survival and proliferation.

SUMMARY

Mounting evidence suggests that H. pylori promotes gastric carcinogenesis using a multifactorial approach. Intriguingly, many of the targeted pathways and mechanisms show commonality with diverse forms of cancer.