Precancerous nature of intestinal metaplasia with increased chance of conversion and accelerated DNA methylation.
Gut
OBJECTIVE:The presence of intestinal metaplasia (IM) is a risk factor for gastric cancer. However, it is still controversial whether IM itself is precancerous or paracancerous. Here, we aimed to explore the precancerous nature of IM by analysing epigenetic alterations. DESIGN:Genome-wide DNA methylation analysis was conducted by EPIC BeadArray using IM crypts isolated by Alcian blue staining. Chromatin immunoprecipitation sequencing for H3K27ac and single-cell assay for transposase-accessible chromatin by sequencing were conducted using IM mucosa. was induced using Tet-on gene expression system in normal cells. RESULTS:IM crypts had a methylation profile unique from non-IM crypts, showing extensive DNA hypermethylation in promoter CpG islands, including those of tumour-suppressor genes. Also, the IM-specific methylation profile, namely epigenetic footprint, was present in a fraction of gastric cancers with a higher frequency than expected, and suggested to be associated with good overall survival. IM organoids had remarkably high expression, and induction in normal cells led to accelerated induction of aberrant DNA methylation, namely epigenetic instability, by increasing DNA methyltransferase activity. IM mucosa showed dynamic enhancer reprogramming, including the regions involved in higher expression. had open chromatin in IM cells but not in gastric cells, and IM cells had frequent closed chromatin of tumour-suppressor genes, indicating their methylation-silencing. expression in IM-derived organoids was upregulated by interleukin-17A, a cytokine secreted by extracellular bacterial infection. CONCLUSIONS:IM cells were considered to have a precancerous nature potentially with an increased chance of converting into cancer cells, and an accelerated DNA methylation induction due to abnormal expression.
10.1136/gutjnl-2023-329492
Role of lncRNAs in Helicobacter pylori and Epstein-Barr virus associated gastric cancers.
Life sciences
Helicobacter pylori infection is a risk factor for the development of gastric cancer (GC), and the role of co-infection with viruses, such as Epstein-Barr virus, in carcinogenesis cannot be ignored. Furthermore, it is now known that genetic factors such as long non-coding RNAs (lncRNAs) are involved in many diseases, including GC. On the other side, they can also be used as therapeutic goals. Modified lncRNAs can cause aberrant expression of genes encoding proximal proteins, which are essential for the development of carcinoma. In this review, we present the most recent studies on lncRNAs in GC, concentrating on their roles in H. pylori and EBV infections, and discuss some of the molecular mechanisms of these GC-related pathogens. There was also a discussion of the research gaps and future perspectives.
10.1016/j.lfs.2023.122316
Microbiota and gastric cancer.
Seminars in cancer biology
The discovery of Helicobacter pylori in 1982 drew to an end the stomach being considered as a sterile organ. Later, the progress in molecular methods, especially Next Generation Sequencing and metagenomics, has highlighted the fact that a diverse microbiota including five major phyla could also be present in the stomach. However, when present, H. pylori is the essential species and it influences the other bacterial communities in terms of richness and evenness. It is now well accepted that H. pylori is the main risk factor for gastric cancer, especially the strains harboring the cag pathogenicity island and the CagA oncoprotein, but the need for other factors from the host and the environment can explain the important difference between those infected and those developing gastric cancer. Several studies showed a difference between the gastric microbiota of patients at various stages of development of gastric premalignant and malignant lesions, showing globally a reduced microbial diversity and an increase in the presence of intestinal commensals, especially with nitrosative functions. Other studies showed an increase in oral microbiota. These data suggest that the gastric microbiota other than H. pylori may play a role in the last steps of gastric carcinogenesis. It must also be noted that in a limited number of cases, a virus: the Epstein Barr Virus is responsible for the evolution toward gastric cancer, while in others the mycobiota also needs to be explored. Finally, the use of mice models allowed an exploration of the role of different gastric microbiota in addition to H. pylori.
10.1016/j.semcancer.2022.05.001
DNA methylation in gastric cancer, related to Helicobacter pylori and Epstein-Barr virus.
Matsusaka Keisuke,Funata Sayaka,Fukayama Masashi,Kaneda Atsushi
World journal of gastroenterology
Gastric cancer is a leading cause of cancer death worldwide, and significant effort has been focused on clarifying the pathology of gastric cancer. In particular, the development of genome-wide analysis tools has enabled the detection of genetic and epigenetic alterations in gastric cancer; for example, aberrant DNA methylation in gene promoter regions is thought to play a crucial role in gastric carcinogenesis. The etiological viewpoint is also essential for the study of gastric cancers, and two distinct pathogens, Helicobacter pylori (H. pylori) and Epstein-Barr virus (EBV), are known to participate in gastric carcinogenesis. Chronic inflammation of the gastric epithelium due to H. pylori infection induces aberrant polyclonal methylation that may lead to an increased risk of gastric cancer. In addition, EBV infection is known to cause extensive methylation, and EBV-positive gastric cancers display a high methylation epigenotype, in which aberrant methylation extends to not only Polycomb repressive complex (PRC)-target genes in embryonic stem cells but also non-PRC-target genes. Here, we review aberrant DNA methylation in gastric cancer and the association between methylation and infection with H. pylori and EBV.
10.3748/wjg.v20.i14.3916
Single-cell transcriptomic profiling uncovers cellular complexity and microenvironment in gastric tumorigenesis associated with Helicobacter pylori.
Journal of advanced research
INTRODUCTION:Helicobacter pylori (H. pylori) infection is the main risk for gastric cancer (GC). However, the cellular heterogeneity and underlying molecular mechanisms in H. pylori-driven gastric tumorigenesis are poorly understood. OBJECTIVE:Here, we generated a single-cell atlas of gastric tumorigenesis comprising 18 specimens of gastritis, gastric intestinal metaplasia (IM) and GC with or without H. pylori infection. METHODS:Single-cell RNA sequencing (scRNA-seq) was performed. Immunofluorescence, immunohistochemistry and qRT-PCR analysis were applied in a second human gastric tissues cohort for validation. Bioinformatics analyses of public TCGA and GEO datasets were applied. RESULTS:Single-cell RNA profile highlights cellular heterogeneity and alterations in tissue ecology throughout the progression of gastric carcinoma. Various cell lineages exhibited unique cancer-associated expression profiles, such as tumor-like epithelial cell subset (EPC), inflammatory cancer-associated fibroblasts (iCAFs) and Tumor-associated macrophage (TAM). Notably, we revealed that the specific epithelial subset enterocytes from the precancerous lesion GIM, exhibited elevated expression of genes related to lipid metabolism, and HNF4G was predicted as its specific transcription factor. Furthermore, we identified differentially expressed genes in H. pylori-positive and negative epithelial cells, fibroblasts and myeloid cells were identified. Futhermore, H. pylori-positive specimens exhibited enriched cell-cell communication, characterized by significantly active TNF, SPP1, and THY1 signaling networks. CONCLUSIONS:Our study provides a comprehensive landscape of the gastric carcinogenesis ecosystem and novel insights into the molecular mechanisms of different cell types in H. pylori-induced GC.
10.1016/j.jare.2024.10.012
The beta1 integrin activates JNK independent of CagA, and JNK activation is required for Helicobacter pylori CagA+-induced motility of gastric cancer cells.
Snider Jared L,Allison Cody,Bellaire Bryan H,Ferrero Richard L,Cardelli James A
The Journal of biological chemistry
The Helicobacter pylori CagA protein is translocated into gastric epithelial cells through a type IV secretion system (TFSS), and published studies suggest CagA is critical for H. pylori-associated carcinogenesis. CagA is thought to be necessary and sufficient to induce the motogenic response observed in response to CagA+ strains, as CagA interacts with proteins involved in adhesion and motility. We report that H. pylori strain 60190 stimulated AGS cell motility through a CagA- and TFSS-dependent mechanism, because strains 60190DeltacagA or 60190DeltacagE (TFSS-defective) did not increase motility. The JNK pathway is critical for H. pylori-dependent cell motility, as inhibition using SP600125 (JNK1/2/3 inhibitor) or a JNK2/3-specific inhibitor blocked motility. JNK mediates H. pylori-induced cell motility by activating paxillin, because JNK inhibition blocked paxillinTyr-118 phosphorylation, and paxillin expression knockdown completely abrogated bacteria-induced motility. Furthermore, JNK and paxillinTyr-118 were activated by 60190DeltacagA but not 60190DeltacagE, demonstrating CagA-independent signaling critical for cell motility. A beta1 integrin-blocking antibody significantly inhibited JNK and paxillinTyr-118 phosphorylation and cell scattering, demonstrating that CagA-independent signaling required for cell motility occurs through beta1. The requirement of both Src and focal adhesion kinase for signaling and motility further suggests the importance of integrin signaling in H. pylori-induced cell motility. Finally, we show that JNK activation occurs independent of known upstream kinases and signaling molecules, including Nod1, Cdc42, Rac1, MKK4, and MKK7, which demonstrates novel signaling leading to JNK activation. We report for the first time that H. pylori mediates CagA-independent signaling that promotes cell motility through the beta1 integrin pathway.
10.1074/jbc.M800289200
H. pylori infection alters repair of DNA double-strand breaks via SNHG17.
Han Taotao,Jing Xiaohui,Bao Jiayu,Zhao Lianmei,Zhang Aidong,Miao Renling,Guo Hui,Zhou Baoguo,Zhang Shang,Sun Jiazeng,Shi Juan
The Journal of clinical investigation
Chronic infections can lead to carcinogenesis through inflammation-related mechanisms. Chronic infection of the human gastric mucosa with Helicobacter pylori is a well-known risk factor for gastric cancer. However, the mechanisms underlying H. pylori-induced gastric carcinogenesis are incompletely defined. We aimed to screen and clarify the functions of long noncoding RNAs (lncRNAs) that are differentially expressed in H. pylori-related gastric cancer. We found that lncRNA SNHG17 was upregulated by H. pylori infection and markedly increased the levels of double-strand breaks (DSBs). SNHG17 overexpression correlated with poor overall survival in patients with gastric cancer. The recruitment of NONO by overabundant nuclear SNHG17, along with the role of cytoplasmic SNHG17 as a decoy for miR-3909, which regulates Rad51 expression, shifted the DSB repair balance from homologous recombination toward nonhomologous end joining. Notably, during chronic H. pylori infection, SNHG17 knockdown inhibited chromosomal aberrations. Our findings suggest that spatially independent deregulation of the SNHG17/NONO and SNHG17/miR-3909/RING1/Rad51 pathways upon H. pylori infection promotes tumorigenesis in gastric cancer by altering the DNA repair system, which is critical for the maintenance of genomic stability. Upregulation of SNHG17 by H. pylori infection might be an undefined link between cancer and inflammation.
10.1172/JCI125581
P27kip1 regulates the apoptotic response of gastric epithelial cells to Helicobacter pylori.
Eguchi H,Carpentier S,Kim S S,Moss S F
Gut
BACKGROUND:Helicobacter pylori infection increases the risk of gastric cancer but the molecular mechanisms responsible are not well understood. Gastric cells chronically exposed to H pylori in vitro develop resistance to apoptosis associated with low levels of p27, a cyclin dependent kinase inhibitor and haplo insufficient tumour suppressor gene that is downregulated in gastric cancer. AIM:To determine whether the low level of p27 protein is responsible for the resistance to apoptosis of gastric cancer cells. METHODS:The effects of increasing the expression of p27 protein were examined by transiently and stably transfecting a plasmid encoding full length p27 mRNA into apoptosis resistant gastric cancer cell lines with low p27 expression that were derived from AGS gastric cancer cells by chronic H pylori coculture followed by dilutional cloning. RESULTS:Low p27 expression in the apoptosis resistant derivative cell lines was associated with an approximate 30% decrease in p27 mRNA and an 80% decrease in p27 protein that was not due to increased proteasome dependent degradation of p27 protein. Transient or stable transfection with p27 constructs partially restored the sensitivity of the apoptosis resistant cells to 5-fluorouracil and H pylori induced apoptosis without altering spontaneous apoptotic cell death. CONCLUSIONS:These results demonstrate that p27 positively regulates, at least in part, the apoptotic response of gastric epithelial cells to H pylori. Low gastric p27 may promote gastric carcinogenesis associated with H pylori infection by inhibiting apoptotic pathways.
10.1136/gut.2003.032144
Upregulation of oncogene Activin A receptor type I by Helicobacter pylori infection promotes gastric intestinal metaplasia via regulating CDX2.
Helicobacter
BACKGROUND:Activin A receptor type I (ACVR1) is involved in tumorigenesis. However, the underlying molecular mechanisms of ACVR1 in gastric cancer (GC) and its association with Helicobacter pylori remained unclear. MATERIALS AND METHODS:The Cancer Genome Atlas (TCGA) and Gene Expression Profiling Interactive Analysis (GEPIA) database were utilized to explore the ACVR1 expression in GC and normal control and its association with survival. The ACVR1 was knocked out using CRISPR/Cas-9; RNA sequencing analysis was performed in AGS cells with ACVR1 knockout and normal control. Functional experiments (CCK-8, colony-forming, and transwell assays) were conducted to demonstrate the role of ACVR1 in cell proliferation, invasion, and metastasis. H. pylori-infected C57/BL6 models were established. ACVR1, p-Smad1/5, and CDX2 were detected in AGS cells cocultured with H. pylori strains. The CDX2 and key elements of BMP signaling pathway were detected in AGS cells with ACVR1 knockout and normal control. In addition, Immunohistochemistry was performed to detect the ACVR1 and CDX2 expression in gastric samples. RESULTS:ACVR1 expression was higher in GC than normal control from TCGA, GEPIA, and samples collected from our hospital (p < 0.05). ACVR1 promoted cell proliferation, migration, and invasion in vitro. Both cagA and cagA H. pylori could upregulate the expression ACVR1 (p < 0.05). Downregulation of ACVR1 inhibited the H. pylori-induced cell proliferation, migration, and invasion (p < 0.05). H. pylori increased the expression of p-Smad 1/5 and CDX2. The CDX2 and key elements of BMP signaling pathway were downregulated in AGS cells with ACVR1 knockout. ACVR1 and CDX2 were upregulated in the stage of intestinal metaplasia (IM). Moreover, ACVR1 and CDX2 expressions were higher in H. pylori-positive group than H. pylori-negative group (p < 0.05). CONCLUSION:Our data indicate that H. pylori infection increases ACVR1 expression, promoting gastric IM via regulating CDX2, which is an essential step in H. pylori carcinogenesis.
10.1111/hel.12849
CagA protein of Helicobacter pylori: a hijacker of gastric epithelial cell signaling.
Handa Osamu,Naito Yuji,Yoshikawa Toshikazu
Biochemical pharmacology
Epidemiological study has shown strong correlation between the Helicobacter pylori (H. pylori) infection and gastric carcinogenesis. However, the mechanism by which H. pylori induces gastric carcinogenesis is not known. In this review, we focused on the product of cytotoxin-associated gene A (CagA), one of the important virulence factors of H. pylori. H. pylori injects CagA protein into the host gastric epithelial cells through its needle-like structure, type IV secretion system. Injected CagA hijacks physiological signal transduction and causes pathological cellular response such as increased cell proliferation, motility, apoptosis and morphological change through different mechanisms. H. pylori has been shown to produce reactive oxygen species (ROS) in infected gastric mucosa. Although the main source of ROS production is possibly host neutrophil, we propose novel source of ROS production in this review; CagA itself can induce ROS production in gastric epithelial cell. Excessive ROS production in gastric epithelial cells can cause DNA damage and thus might involve in gastric carcinogenesis. Understanding the molecular mechanism by which H. pylori-induced carcinogenesis is important for developing new strategies against gastric cancer.
10.1016/j.bcp.2006.10.022
Comprehensive Integration of Genome-Wide Association and Gene Expression Studies Reveals Novel Gene Signatures and Potential Therapeutic Targets for -Induced Gastric Disease.
Frontiers in immunology
is a gram-negative bacterium that colonizes the human gastric mucosa and can lead to gastric inflammation, ulcers, and stomach cancer. Due to the increase in antimicrobial resistance new methods to identify the molecular mechanisms of induced pathology are urgently needed. Here we utilized a computational biology approach, harnessing genome-wide association and gene expression studies to identify genes and pathways determining disease development. We mined gene expression data related to infection and its complications from publicly available databases to identify four human datasets as discovery datasets and used two different multi-cohort analysis pipelines to define a induced gene signature. An initial -signature was curated using the MetaIntegrator pipeline and validated in cell line model datasets. With this approach we identified cell line models that best match gene regulation in human pathology. A second analysis pipeline through NetworkAnalyst was used to refine our initial signature. This approach defined a 55-gene signature that is stably deregulated in disease conditions. The 55-gene signature was validated in datasets from human gastric adenocarcinomas and could separate tumor from normal tissue. As only a small number of patients develop cancer, this gene-signature must interact with other host and environmental factors to initiate tumorigenesis. We tested for possible interactions between our curated gene signature and host genomic background mutations and polymorphisms by integrating genome-wide association studies (GWAS) and known oncogenes. We analyzed public databases to identify genes harboring single nucleotide polymorphisms (SNPs) associated with gastric pathologies and driver genes in gastric cancers. Using this approach, we identified 37 genes from GWA studies and 61 oncogenes, which were used with our 55-gene signature to map gene-gene interaction networks. In conclusion, our analysis defines a unique gene signature driven by infection at early phases and that remains relevant through different stages of pathology up to gastric cancer, a stage where itself is rarely detectable. Furthermore, this signature elucidates many factors of host gene and pathway regulation in infection and can be used as a target for drug repurposing and testing of infection models suitability to investigate human infection.
10.3389/fimmu.2021.624117