Enhanced de novo lipogenesis mediated by sterol regulatory element–binding proteins (SREBPs) is thought to be involved in nonalcoholic steatohepatitis (NASH) pathogenesis. In this study, we assessed the impact of SREBP inhibition on NASH and liver cancer development in murine models. Unexpectedly, SREBP inhibition via deletion of the SREBP cleavage–activating protein (SCAP) in the liver exacerbated liver injury, fibrosis, and carcinogenesis despite markedly reduced hepatic steatosis. These phenotypes were ameliorated by restoring SREBP function. Transcriptome and lipidome analyses revealed that SCAP/SREBP pathway inhibition altered the fatty acid (FA) composition of phosphatidylcholines due to both impaired FA synthesis and disorganized FA incorporation into phosphatidylcholine via lysophosphatidylcholine acyltransferase 3 (LPCAT3) downregulation, which led to endoplasmic reticulum (ER) stress and hepatocyte injury. Supplementation with phosphatidylcholines significantly improved liver injury and ER stress induced by SCAP deletion. The activity of the SCAP/SREBP/LPCAT3 axis was found to be inversely associated with liver fibrosis severity in human NASH. SREBP inhibition also cooperated with impaired autophagy to trigger liver injury. Thus, excessively strong and broad lipogenesis inhibition was counterproductive for NASH therapy; this will have important clinical implications in NASH treatment.

Several stem cell markers within the gastrointestinal epithelium have been identified in mice. One of the best characterized is Lgr5 (leucine-rich repeat-containing G-protein coupled receptor 5) and evidence suggests that Lgr5+ cells in the gut are the origin of gastrointestinal cancers. Reserve or facultative stem or progenitor cells with the ability to convert to Lgr5+ cells following injury have also been identified. Unlike the intestine, where Lgr5+ cells at the crypt base act as active stem cells, the stomach may contain unique stem cell populations, since gastric Lgr5+ cells seem to behave as a reserve rather than active stem cells, both in the corpus and in the antral glands. Gastrointestinal stem cells are supported by a specific microenvironment, the stem cell niche, which also promotes tumorigenesis. This review focuses on stem cell markers in the gut and their supporting niche factors. It also discusses the molecular mechanisms that regulate stem cell function and tumorigenesis.

Nerves can regulate tumorigenesis and cancer progression. However, clarification of the role of axon guidance molecules in tumorigenesis, innervation, and metastasis is required to better understand the tumor-promoting functions of nerves. Using murine KrasG12D-mutant pancreatic organoids, we screened axon guidance molecules and identified netrin-1 upregulation. Netrin-1 was also upregulated in vivo during pancreatic tumorigenesis in humans and mice. Mutant KRAS and β-adrenergic signaling upregulated netrin-1 and its receptor NEO1 in epithelial cells in part through the MAPK pathway. Ex vivo culture of celiac ganglia showed that netrin-1 promoted the axonogenesis of sympathetic neurons through nerve NEO1. In the Pdx1-Cre;LSL-KrasG12D/+ model, knockout (KO) of Ntn1, which encodes netrin-1, decreased sympathetic innervation and the development of pancreatic intraepithelial neoplasia. Treatment of pancreatic tumor organoids with recombinant netrin-1 enhanced cell growth, epithelial–mesenchymal transition (EMT), and cancer stemness with the upregulation of ZEB1 and SOX9 through NEO1-mediated activation of focal adhesion kinase (FAK). In Pdx1-Cre;LSL-KrasG12D/+;LSL-Trp53R172H/+ mice, Ntn1 KO reduced innervation, FAK phosphorylation, and the features of EMT and stemness to extend mouse survival. In a liver metastasis model of pancreatic ductal adenocarcinoma (PDAC), treatment with a netrin-1–neutralizing antibody or tumoral KO of Neo1 reduced ZEB1 and SOX9 and decreased tumor progression. In contrast, netrin-1 overexpression promoted innervation and the progression of PDAC liver metastasis. These data suggest that the netrin-1/NEO1 axis is a key regulator of PDAC progression, directly influencing cancer cell stemness and EMT while indirectly promoting tumor growth through nerves. Inhibiting the netrin-1 pathway could represent a potential therapeutic approach for PDAC. Significance: Netrin-1 promotes pancreatic tumorigenesis and metastasis directly and indirectly through nerves, highlighting the importance of tumor cell-nerve cross-talk in cancer and the potential of netrin-1 blockade as a treatment strategy.

The mechanism of H. pylori-induced atrophy and metaplasia has not been fully understood. Here, we demonstrate the novel role of Apoptosis signal-regulating kinase 1 (ASK1) and downstream MAPKs as a regulator of host immune responses and epithelial maintenance against H. pylori infection. ASK1 gene deficiency resulted in enhanced inflammation with numerous inflammatory cells including Gr-1+CD11b+ myeloid-derived suppressor cells (MDSCs) recruited into the infected stomach. Increase of IL-1β release from apoptotic macrophages and enhancement of TH1-polarized immune responses caused STAT1 and NF-κB activation in epithelial cells in ASK1 knockout mice. Dysregulated immune and epithelial activation in ASK1 knockout mice led to dramatic expansion of gastric progenitor cells and massive metaplasia development. Bone marrow transplantation experiments revealed that ASK1 in inflammatory cells is critical for inducing immune disorder and metaplastic changes in epithelium, while ASK1 in epithelial cells regulates cell proliferation in stem/progenitor zone without changes in inflammation and differentiation. These results suggest that H. pylori-induced immune cells may regulate epithelial homeostasis and cell fate as an inflammatory niche via ASK1 signaling.

Objective Reflux oesophagitis (RO) is one of the most common diseases encountered by gastroenterologists and primary care physicians. However, few epidemiological studies have investigated the association of medication use and RO. This study aimed to investigate the prevalence of RO and its risk factors, particularly with respect to medication use. Methods This retrospective, cross-sectional study included consecutive patients who underwent oesophagogastroduodenoscopy (OGD) and were assessed using questionnaires at the National Center for Global Health and Medicine (Shinjuku, Tokyo, Japan) between October 2015 and December 2021. The questionnaire collected data on patient characteristics, medical history, smoking and alcohol consumption, and medications that patients were taking at the time of OGD. Results Among the 13 993 eligible patients, the prevalence of RO was 11.8%. Multivariate logistic regression analysis indicated that male sex (OR=1.52 (95% CI 1.35 to 1.72), p<0.001); obesity (OR=1.57 (95% CI 1.40 to 1.77), p<0.001); smoking (OR=1.19 (95% CI 1.02 to 1.38), p=0.026); alcohol consumption (OR=1.20 (95% CI 1.07 to 1.35), p=0.002); diabetes (OR=1.19 (95% CI 1.02 to 1.39), p=0.029); hiatal hernia (OR=3.10 (95% CI 2.78 to 3.46), p<0.001); absence of severe gastric atrophy (OR=2.14 (95% CI 0.39 to 0.56), p<0.001); and the use of calcium channel blockers (CCBs) (OR=1.22 (95% CI 1.06 to 1.40), p=0.007), theophylline (OR=2.13 (95% CI 1.27 to 3.56), p=0.004), and non-steroidal anti-inflammatory drugs (NSAIDs) (OR=1.29 (95% CI 1.03 to 1.61), p=0.026) were independent predictors of RO. Conclusion RO was present in 11.8% of patients. Use of CCBs, theophylline, and NSAIDs were independent predictors of RO.