Gastrointestinal neoplasia: carcinogenic interaction between bile acids and Helicobacter pylori in the stomach

The role of metal ions in the occurrence, progression, drug resistance, and biological characteristics of gastric cancer

Metal ions exert pivotal functions within the human body, encompassing essential roles in upholding cell structure, gene expression regulation, and catalytic enzyme activity. Additionally, they significantly influence various pathways implicated in divergent mechanisms of cell death. Among the prevailing malignant tumors of the digestive tract worldwide, gastric cancer stands prominent, exhibiting persistent high mortality rates. A compelling body of evidence reveals conspicuous ion irregularities in tumor tissues, encompassing gastric cancer. Notably, metal ions have been observed to elicit distinct contributions to the progression, drug resistance, and biological attributes of gastric cancer. This review consolidates pertinent literature on the involvement of metal ions in the etiology and advancement of gastric cancer. Particular attention is directed towards metal ions, namely, Na, K, Mg, Ca, Fe, Cu, Zn, and Mn, elucidating their roles in the initiation and progression of gastric cancer, cellular demise processes, drug resistance phenomena, and therapeutic approaches.

NNMT enriches for AQP5+ cancer stem cells to drive malignant progression in early gastric cardia adenocarcinoma

OBJECTIVE

Early gastric cardia adenocarcinoma (EGCA) is a highly heterogeneous cancer, and the understanding of its classification and malignant progression is limited. This study explored the cellular and molecular heterogeneity in EGCA using single-cell RNA sequencing (scRNA-seq).

DESIGN

scRNA-seq was conducted on 95 551 cells from endoscopic biopsies of low-grade intraepithelial neoplasia, well/moderately/poorly differentiated EGCA and their paired adjacent nonmalignant biopsy samples. Large-scale clinical samples and functional experiments were employed.

RESULTS

Integrative analysis of epithelial cells revealed that chief cells, parietal cells and enteroendocrine cells were rarely detected in the malignant epithelial subpopulation, whereas gland and pit mucous cells and AQP5+ stem cells were predominant during malignant progression. Pseudotime and functional enrichment analyses showed that the WNT and NF-κB signalling pathways were activated during the transition. Cluster analysis of heterogeneous malignant cells revealed that NNMT-mediated nicotinamide metabolism was enriched in gastric mucin phenotype cell population, which was associated with tumour initiation and inflammation-induced angiogenesis. Furthermore, the expression level of NNMT was gradually increased during the malignant progression and associated with poor prognosis in cardia adenocarcinoma. Mechanistically, NNMT catalysed the conversion of nicotinamide to 1-methyl nicotinamide via depleting S-adenosyl methionine, which led to a reduction in H3K27 trimethylation (H3K27me3) and then activated the WNT signalling pathway to maintain the stemness of AQP5+ stem cells during EGCA malignant progression.

CONCLUSION

Our study extends the understanding of the heterogeneity of EGCA and identifies a functional NNMT+/AQP5+ population that may drive malignant progression in EGCA and could be used for early diagnosis and therapy.

Helicobacter pylori promotes gastric intestinal metaplasia through activation of IRF3-mediated kynurenine pathway

BACKGROUND

Metabolic reprogramming is a critical event for cell fate and function, making it an attractive target for clinical therapy. The function of metabolic reprogramming in Helicobacter pylori (H. pylori)-infected gastric intestinal metaplasia remained to be identified.

METHODS

Xanthurenic acid (XA) was measured in gastric cancer cells treated with H. pylori or H. pylori virulence factor, respectively, and qPCR and WB were performed to detect CDX2 and key metabolic enzymes expression. A subcellular fractionation approach, luciferase and ChIP combined with immunofluorescence were applied to reveal the mechanism underlying H. pylori mediated kynurenine pathway in intestinal metaplasia in vivo and in vitro.

RESULTS

Herein, we, for the first time, demonstrated that H. pylori contributed to gastric intestinal metaplasia characterized by enhanced Caudal-related homeobox transcription factor-2 (CDX2) and mucin2 (MUC2) expression, which was attributed to activation of kynurenine pathway. H. pylori promoted kynurenine aminotransferase II (KAT2)-mediated kynurenine pathway of tryptophan metabolism, leading to XA production, which further induced CDX2 expression in gastric epithelial cells. Mechanically, H. pylori activated cyclic guanylate adenylate synthase (cGAS)-interferon regulatory factor 3 (IRF3) pathway in gastric epithelial cells, leading to enhance IRF3 nuclear translocation and the binding of IRF3 to KAT2 promoter. Inhibition of KAT2 could significantly reverse the effect of H. pylori on CDX2 expression. Also, the rescue phenomenon was observed in gastric epithelial cells treated with H. pylori after IRF3 inhibition in vitro and in vivo. Most importantly, phospho-IRF3 was confirmed to be a clinical positive relationship with CDX2.

CONCLUSION

These finding suggested H. pylori contributed to gastric intestinal metaplasia through KAT2-mediated kynurenine pathway of tryptophan metabolism via cGAS-IRF3 signaling, targeting the kynurenine pathway could be a promising strategy to prevent gastric intestinal metaplasia caused by H. pylori infection. Video Abstract.

Endoscopic Transoral Outlet Reduction for the Treatment of Biliary Reflux Symptoms in Patients After One-Anastomosis Gastric Bypass-a Case Series

PURPOSE

OAGB is the third most common bariatric surgery. Biliary reflux (BR) is an inherent complication of this unique anatomy, although there is still controversy regarding its significance and long-term risks including carcinogenesis. To date, there is no effective treatment for BR with conversion to RYGB reserved for refractory patients. TORe is an effective treatment for weight-regain and dumping syndrome after RYGB. We hypothesized that narrowing the anastomosis would decrease the amount of bile refluxate entering the stomach and esophagus in patients with BR symptoms after OAGB and alleviate symptoms. The purpose of this study is to evaluate the efficacy of TORe for the treatment of BR symptoms after OAGB.

MATERIALS AND METHODS

BR was diagnosed clinically in patients after OAGB using the gastroesophageal reflux disease health-related quality of life (GERD-HRQL) instrument after treatment with high-dose proton pump inhibitor (PPI) excluded possible acid reflux. TORe was carried out using a suture pattern that narrowed and elongated the anastomosis. All patients were prospectively followed.

RESULTS

Twelve patients, post-OAGB, underwent TORe for BR. Symptoms resolved in 9 (75%) patients. GERD-HRQL score at 6 months declined from an average of 33.7 (SD 1.9) before the procedure to 16.1 (SD 10, p < 0.001). In one case, a small perforation was identified during the procedure and was immediately sutured with no further sequela.

DISCUSSION

TORe appears a safe and effective treatment for BR symptoms after OAGB, at least in the short term. Accurate tools for BR diagnosis, a larger cohort, and longer follow-up periods are needed to better show the effectiveness and durability of this treatment option.

Bioactive polysaccharides promote gut immunity via different ways

Numerous kinds of bioactive polysaccharides are identified as having intestinal immunomodulatory activity; however, the ways in which the different polysaccharides work differ. Therefore, we selected nine representative bioactive polysaccharides, including xanthan gum, inulin, guar gum, arabinogalactan, carrageenan, glucomannan, araboxylan, xylan, and fucoidan, and compared their intestinal immunomodulatory mechanisms. A cyclophosphamide (CTX)-induced immunosuppressed model was used in this experiment, and the effects of these polysaccharides on the number of T cells in the intestinal mucosa, expression of transcription factors and inflammatory factors, intestinal metabolome and gut microbiota were compared and discussed. The results revealed that the nine polysaccharides promote intestinal immunity in different ways. In detail, guar gum, inulin and glucomannan better alleviated immune suppression in intestinal mucosal T cells. Inulin improved the intestinal microenvironment by significantly upregulating the abundance of Lactobacillus and Monoglobus and promoted short chain fatty acid (SCFA) production. Fucoidan and carrageenan promoted the colonization of the beneficial bacteria Rikenella and Roseburia. In addition, fucoidan, inulin and carrageenan inhibited the colonization of harmful bacteria Helicobacter, upregulated the abundance of Clostridia_UCG-014 and alleviated the accumulation of amino acids, bile acids and indoles in the large intestine. In conclusion, our study uncovered the different intestinal immunomodulatory mechanisms of the different polysaccharides and provided a guideline for the development of superior intestinal immunomodulatory polysaccharides.

Bile acids as carcinogens in the colon and at other sites in the gastrointestinal system

Colon cancer incidence is associated with a high-fat diet. Such a diet is linked to elevated levels of bile acids in the gastrointestinal system and the circulation. Secondary bile acids are produced by microorganisms present at high concentrations in the colon. Recent prospective studies and a retrospective study in humans associate high circulating blood levels of secondary bile acids with increased risk of colon cancer. Feeding mice a diet containing a secondary bile acid, so their feces have the bile acid at a level comparable to that in the feces of humans on a high-fat diet, also causes colon cancer in the mice. Studies using human cells grown in culture illuminate some mechanisms by which bile acids cause cancer. In human cells, bile acids cause oxidative stress leading to oxidative DNA damage. Increased DNA damage increases the occurrence of mutations and epimutations, some of which provide a cellular growth advantage such as apoptosis resistance. Cells with such mutations/epimutations increase by natural selection. Apoptosis, or programmed cell death, is a beneficial process that eliminates cells with unrepaired DNA damage, whereas apoptosis-resistant cells are able to survive DNA damage using inaccurate repair processes. This results in apoptosis-resistant cells having more frequent mutations/epimutations, some of which are carcinogenic. The experiments on cultured human cells have provided a basis for understanding at the molecular level the human studies that recently reported an association of bile acids with colon cancer, and the mouse studies showing directly that bile acids cause colon cancer. Similar, but more limited, findings of an association of dietary bile acids with other cancers of the gastrointestinal system suggest that understanding the role of bile acids in colon carcinogenesis may contribute to understanding carcinogenesis in other organs.

Liuwei Dihuang formula ameliorates chronic stress-induced emotional and cognitive impairments in mice by elevating hippocampal O-GlcNAc modification

A substantial body of evidence has indicated that intracerebral O-linked N-acetyl-β-D-glucosamine (O-GlcNAc), a generalized post-translational modification, was emerging as an effective regulator of stress-induced emotional and cognitive impairments. Our previous studies showed that the Liuwei Dihuang formula (LW) significantly improved the emotional and cognitive dysfunctions in various types of stress mouse models. In the current study, we sought to determine the effects of LW on intracerebral O-GlcNAc levels in chronic unpredictable mild stress (CUMS) mice. The dynamic behavioral tests showed that anxiety- and depression-like behaviors and object recognition memory of CUMS mice were improved in a dose-dependent manner after LW treatment. Moreover, linear discriminate analysis (LEfSe) of genera abundance revealed a significant difference in microbiome among the study groups. LW showed a great impact on the relative abundance of these gut microbiota in CUMS mice and reinstated them to control mouse levels. We found that LW potentially altered the Uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) biosynthesis process, and the abundance of O-GlcNAcase (OGA) and O-GlcNAc transferase (OGT) in CUMS mice, which was inferred using PICRUSt analysis. We further verified advantageous changes in hippocampal O-GlcNAc modification of CUMS mice following LW administration, as well as changes in the levels of OGA and OGT. In summary, LW intervention increased the levels of hippocampal O-GlcNAc modification and ameliorated the emotional and cognitive impairments induced by chronic stress in CUMS mice. LW therefore could be considered a potential prophylactic and therapeutic agent for chronic stress.