Cancer stem cells (CSCs) depend on the tumor microenvironment (TME) to sustain their stem-like properties by recruiting monocytes and reprogramming them into tumor-associated macrophages (TAMs), which in turn promote tumor progression. This review explores CSC-TAM interactions, emphasizing how CSCs drive monocyte recruitment and TAM polarization. We discuss how TAMs enhance CSC stemness and niche maintenance through chemokines, cytokines, exosome-mediated miRNA transfer, direct interactions, and extracellular matrix (ECM) remodeling. Furthermore, we examine therapeutic strategies targeting TAMs, including inhibiting TAM differentiation, reprogramming TAM polarization, and leveraging immune checkpoint blockade and CAR-macrophage immunotherapy to improve cancer treatment outcomes.

Oncogenic codon V600E mutations of the BRAF gene affect 10-15% of colorectal cancers, resulting in activation of the MAPK/ERK signaling pathway and increased cell proliferation and survival. BRAF-mutated colorectal tumors are often microsatellite unstable and characterized by high DNA methylation levels. However, the mechanistic link between BRAF mutations and hypermethylation remains controversial. Understanding this link, particularly in microsatellite stable tumors is of great interest as these often show poor survival. We characterized the metabolomic, epigenetic and transcriptomic patterns of altogether 39 microsatellite stable BRAF-mutated colorectal cancers. Metabolomic analysis of tumor tissue showed low levels of vitamin C and its metabolites in BRAF-mutated tumors. Gene expression analysis indicated dysregulation of vitamin C antioxidant activity in these lesions. As vitamin C is an important cofactor for the activity of TET DNA demethylase enzymes, low vitamin C levels could directly contribute to the high methylation levels in these tumors by decreasing enzymatic TET activity. Vitamin C transporter gene SLC23A1 expression, as well as vitamin C metabolite levels, were inversely correlated with DNA methylation levels. This work proposes a new mechanistic link between BRAF mutations and hypermethylation, inspiring further work on the role of vitamin C in the genesis of BRAF-mutated colorectal cancer.

Peutz-Jeghers syndrome (PJS) is associated with early-onset gastrointestinal polyposis caused by hereditary inactivating pathogenic variants in the tumor suppressor gene STK11 (LKB1). Due to lack of prophylactic therapies, management of PJS polyps requires frequent surveillance. Interestingly, studies in mouse models have revealed that stromal cells drive the polyp formation, but detailed understanding of the cell types and interactions involved has been lacking. Using single-cell RNA sequencing of PJS mouse model polyps, we here identify a polyp-enriched crypt top fibroblast (pCTF) cluster characterized by a transcriptional signature also enriched in PJS patient polyps. The pCTF signature was also noted in primary fibroblasts in vitro following acute STK11 loss. Targeted deletion of Stk11 in crypt top fibroblasts using Foxl1-Cre led to upregulation of the pCTF signature genes and later to polyposis. pCTFs displayed similarity to inflammation-associated fibroblasts, and polyposis was exacerbated by inflammation. Cell-cell communication analysis identified interleukin 11 (IL-11) as a potential pCTF inducer, and consistent with this, IL-11 was required for fibroblast reprogramming toward pCTFs following STK11 loss. Importantly, a neutralizing IL-11 antibody efficiently reduced polyp formation in a PJS model indicating a key, targetable role for IL-11 in polyp development. Together the results characterize pCTFs as a PJS polyp-enriched fibroblast subset and identify IL-11 as a key mediator of fibroblast reprogramming and a potential therapeutic target in PJS. © 2025 The Pathological Society of Great Britain and Ireland.

Despite recent advances in gastric cancer therapy, chemotherapy resistance and lack of methods for selecting combination regimens remain major problems. Organoids, which provide a culture system that more closely resembles tumor cell organization than traditional cell lines, can be established from surgical specimens with a high success rate and are widely used for drug sensitivity assays. In this study, we aimed to identify a novel biomarker for predicting multidrug resistance using gastric cancer organoids (GCOs). We evaluated 5-fluorouracil or oxaliplatin-resistant GCOs to find novel biomarkers that reflect multidrug resistance in gastric cancer. To examine the resistance mechanisms, RNA-sequencing analysis and ex vivo drug sensitivity testing were performed. The association of biomarkers with patient prognosis and chemotherapy efficacy was evaluated using three original cohorts with a total of 230 cases. The results were also validated with two independent public cohorts and single-cell RNA sequence data. Increased expression of peptidase inhibitor 3 (PI3) was detected in all 5-fluorouracil or oxaliplatin-resistant GCOs. Our findings suggest a potential association of PI3 expression with ribosome biosynthesis and RNA metabolism under organoid conditions. We also found that PI3 overexpression promoted 5-fluorouracil/oxaliplatin/cisplatin resistance but not paclitaxel resistance. Immunohistochemical evaluation of PI3 expression revealed that the PI3-positive gastric cancer group had a poorer outcome, especially in terms of time to recurrence. PI3 positivity was also an independent predictor of relapse after chemotherapy with DNA-damaging agents. PI3 promotes DNA-damaging drug resistance through multiple downstream regulations related to RNA and ribosomal metabolism. PI3 may be useful as a biomarker for the therapeutic selection of non-DNA-damaging agents. © 2025 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Gastrin is secreted following a rise in gastric pH, leading to gastric acid secretion. Sleeve gastrectomy (SG), a bariatric surgery where 80% of the gastric corpus is excised, presents a challenge for gastric pH homeostasis. Using histology, and single-cell RNA sequencing of the gastric epithelium in 12 women, we observed that SG is associated with an increase in a sub-population of acid-secreting parietal cells that overexpress respiratory enzymes and an increase in histamine-secreting enterochromaffin-like cells (ECLs). ECLs of SG-operated patients overexpressed genes coding for biosynthesis of neuropeptides and serotonin. Mathematical modeling showed that pH homeostasis by gastrin is analogous to non-linear proportional and integral control, that drives adaptation of the epithelium to acid-secretion demand. Quantitative model predictions were validated in patients. The results demonstrate human gastric epithelium remodeling following SG at the molecular and cellular levels, and more generally how trophic hormones enable robust adaptation of tissue function to meet physiological demand.

Organoid technology provides a transformative approach to understand human physiology and pathology, offering valuable insights for scientific research and therapeutic development. Human gastric organoids, in particular, have gained significant interest for applications in disease modeling, drug discovery, and studies of tissue regeneration and homeostasis. However, the lack of standardized quality control has limited their extensive clinical applications. The "Human Gastric Organoids" is part of a series of guidelines for human gastric organoids in China, which establishes comprehensive standards on terminology, technical specifications, testing methods, inspection rules, usage instructions, labeling, transportation, and storage, developed by experts from the Chinese Society for Cell Biology and its branch societies. Released on October 29, 2024, this guideline aims to establish standardized protocols, enhance institutional practices, and promote international standardization for clinical and research applications of human gastric organoids.

Cell plasticity refers to the deviation of cells from normal terminal differentiation states when faced with environmental and genetic toxic stresses, resulting in the phenomenon of transforming into other cell or tissue phenotypes. Unlocking phenotype plasticity has been defined as a hallmark of malignant tumors. The stomach is one of the organs in the body with the highest degree of self-renewal and exhibits significant cell plasticity. In this paper, based on the review of the characteristics of normal differentiation of gastric epithelial cells and their markers, the four main phenotypes of gastric epithelial cell remodeling and their relationship with gastric cancer (GC) are drawn. Furthermore, we summarize the regulatory factors and mechanisms that affect gastric epithelial cell plasticity and outline the current status of research and future prospection for the treatment targeting gastric epithelial cell plasticity. This study has important theoretical reference value for the in-depth exploration of epithelial cell plasticity and the tumor heterogeneity caused by it, as well as for the precise treatment of GC.

Chronic atrophic gastritis (CAG) is a prevalent digestive system disease characterized by atrophy of the gastric mucosa and the disappearance of inherent gastric glands. According to the theory of Correa's cascade, CAG is an important pathological stage in the transformation from normal condition to gastric carcinoma. In recent years, the global incidence of CAG has been increasing due to pathogenic factors, including Helicobacter pylori infection, bile reflux, and the consumption of processed meats. In this review, we comprehensively described the etiology and clinical diagnosis of CAG. We focused on elucidating the regulatory mechanisms and promising therapeutic targets in CAG, with the expectation of providing insights and theoretical support for future research on CAG.

Helicobacter pylori infection predisposes carriers to a high risk of developing gastric cancer. The cell-of-origin of antral gastric cancer is the Lgr5+ stem cell. Here, we show that infection of antrum-derived gastric organoid cells with H. pylori increases the expression of the stem cell marker Lgr5 as determined by immunofluorescence microscopy, qRT-PCR, and Western blotting, both when cells are grown and infected as monolayers and when cells are exposed to H. pylori in 3D structures. H. pylori exposure increases stemness properties as determined by spheroid formation assay. Lgr5 expression and the acquisition of stemness depend on a functional type IV secretion system (T4SS) and at least partly on the T4SS effector CagA. The pharmacological inhibition or genetic ablation of NF-κB reverses the increase in Lgr5 and spheroid formation. Constitutively active Wnt/β-catenin signaling because of Apc inactivation exacerbates H. pylori-induced Lgr5 expression and stemness, both of which persist even after eradication of the infection. The combined data indicate that H. pylori has stemness-inducing properties that depend on its ability to activate NF-κB signaling.

WNT signaling is central to spatial tissue arrangement and regulating stem cell activity, and it represents the hallmark of gastrointestinal cancers. Although its role in driving intestinal tumors is well characterized, WNT's role in gastric tumorigenesis remains elusive.

We have developed mouse models to control the specific expression of an oncogenic form of β-catenin (CTNNB1) in combination with MYC activation in Lgr5+ cells of the gastric antrum. We used multiomics approaches applied in vivo and in organoid models to characterize their cooperation in driving gastric tumorigenesis.

We report that constitutive β-catenin stabilization in the stomach has negligible oncogenic effects and requires MYC activation to induce gastric tumor formation. Although physiologically low MYC levels in gastric glands limit β-catenin transcriptional activity, increased MYC expression unleashes the WNT oncogenic transcriptional program, promoting β-catenin enhancer invasion without a direct transcriptional cooperation. MYC activation induces a metabolic rewiring that suppresses lysosomal biogenesis through mTOR and ERK activation and MiT/TFE inhibition. This prevents EPCAM degradation by macropinocytosis, promoting β-catenin chromatin accumulation and activation of WNT oncogenic transcription.

Our results uncovered a new signaling framework with important implications for the control of gastric epithelial architecture and WNT-dependent oncogenic transformation.

The existence of heterogeneity has plunged cancer treatment into a challenging dilemma. We profiled malignant epithelial cells from 5 gastric adenocarcinoma patients through single-cell sequencing (scRNA-seq) analysis, demonstrating the heterogeneity of gastric adenocarcinoma (GA), and identified the CCKBR+ stem cell-like cancer cells associated poorly differentiated and worse prognosis. We further conducted targeted analysis using single-cell transcriptome libraries, including 40 samples, to confirm these screening results. In addition, we revealed that FOXOs are involved in the progression and development of CCKBR+ gastric adenocarcinoma. Inhibited the expression of FOXOs and disrupting cancer cell stemness reduce the CCKBR+ GA organoid formation and impede tumor progression. Mechanically, CUT&Tag sequencing and Lectin pulldown revealed that FOXOs can activate ST3GAL3/4/5 as well as ST6GALNAC6, promoting elevated sialyation levels in CCKBR+ tumor cells. This FOXO-sialyltransferase axis contributes to the maintenance of homeostasis and the growth of CCKBR+ tumor cells. This insight provides novel perspectives for developing targeted therapeutic strategies aimed at the treating CCKBR associated gastric cancer.

Although aberrant activation of the KRAS and PI3K pathway alongside TP53 mutations account for frequent aberrations in human gastric cancers, neither the sequence nor the individual contributions of these mutations have been clarified. Here, we establish an allelic series of mice to afford conditional expression in the glandular epithelium of KrasG12D;Pik3caH1047R or Trp53R172H and/or ablation of Pten or Trp53. We find that KrasG12D;Pik3caH1047R is sufficient to induce adenomas and that lesions progress to carcinoma when also harboring Pten deletions. An additional challenge with either Trp53 loss- or gain-of-function alleles further accelerated tumor progression and triggered metastatic disease. While tumor-intrinsic STAT3 signaling in response to gp130 family cytokines remained as a gatekeeper for all stages of tumor development, metastatic progression required a mutant Trp53-induced interleukin (IL)-11 to IL-6 dependency switch. Consistent with the poorer survival of patients with high IL-6 expression, we identify IL-6/STAT3 signaling as a therapeutic vulnerability for TP53-mutant gastric cancer.

The 43rd Annual Conference of the Indian Association of Cancer Research (IACR) was held between 19th and 22nd January 2024 at the Indian Institute of Education and Research (IISER), Pune, India. Cancer is the second leading cause of death globally; efforts have been made to understand and treat this deadly disease for several decades. The 43rd IACR, organised by Mayurika Lahiri, Kundan Sengupta, Nagaraj Balasubramanian, Mridula Nambiar, Krishanpal Karmodiya, and Siddhesh Kamat, highlighted recent advances in cancer research, with implications in therapeutics at the forefront of the discussions. The meeting proved to be a promising platform for cancer researchers ranging from graduate and postdoctoral students to subject experts in varied aspects of cancer biology to showcase their research, ideate with their peers, and form collaborations.

Nanoparticles of a particular, evolutionarily old inorganic polymer found across the biological kingdoms have attracted increasing interest in recent years not only because of their crucial role in metabolism but also their potential medical applicability: it is inorganic polyphosphate (polyP). This ubiquitous linear polymer is composed of 10-1000 phosphate residues linked by high-energy anhydride bonds. PolyP causes induction of gene activity, provides phosphate for bone mineralization, and serves as an energy supplier through enzymatic cleavage of its acid anhydride bonds and subsequent ATP formation. The biomedical breakthrough of polyP came with the development of a successful fabrication process, in depot form, as Ca- or Mg-polyP nanoparticles, or as the directly effective polymer, as soluble Na-polyP, for regenerative repair and healing processes, especially in tissue areas with insufficient blood supply. Physiologically, the platelets are the main vehicles for polyP nanoparticles in the circulating blood. To be biomedically active, these particles undergo coacervation. This review provides an overview of the properties of polyP and polyP nanoparticles for applications in the regeneration and repair of bone, cartilage, and skin. In addition to studies on animal models, the first successful proof-of-concept studies on humans for the healing of chronic wounds are outlined.

Gastric cancer is a significant global health concern with complex molecular underpinnings influencing disease progression and patient outcomes. Various molecular drivers were reported, and these studies offered potential avenues for targeted therapies, biomarker discovery, and the development of precision medicine strategies. However, it was posed that the heterogeneity of the disease and the complexity of the molecular interactions are still challenging. By seamlessly integrating data from single-cell RNA sequencing (scRNA-seq) and bulk RNA sequencing (bulk RNA-seq), we embarked on characterizing molecular signatures and establishing a prognostic signature for this complex malignancy. We offered a holistic view of gene expression landscapes in gastric cancer, identified 226 candidate marker genes from 3 different dimensions, and unraveled key players' risk stratification and treatment decision-making. The convergence of molecular insights in gastric cancer progression occurs at multiple biological scales simultaneously. The focal point of this study lies in developing a prognostic model, and we amalgamated four molecular signatures (COL4A1, FKBP10, RNASE1, SNCG) and three clinical parameters using advanced machine-learning techniques. The model showed high predictive accuracy, with the potential to revolutionize patient care by using clinical variables. This will strengthen the reliability of the model and enable personalized therapeutic strategies based on each patient's unique molecular profile. In summary, our research sheds light on the molecular underpinnings of gastric cancer, culminating in a powerful prognostic tool for gastric cancer. With a firm foundation in biological insights and clinical implications, our study paves the way for future validations and underscores the potential of integrated molecular analysis in advancing precision oncology.

Cancer stemness is recognized as a key component of tumor development. Previously coined "cancer stem cells" (CSCs) and believed to be a rare population with rigid hierarchical organization, there is good evidence to suggest that these cells exhibit a plastic cellular state influenced by dynamic CSC-niche interplay. This revelation underscores the need to reevaluate the hallmarks of cancer stemness. Herein, we summarize the techniques used to identify and characterize the state of these cells and discuss their defining and emerging hallmarks, along with their enabling and associated features. We also highlight potential future directions in this field of research.

Chronic atrophic gastritis (AG) is initiated mainly by Helicobacter pylori infection, which may progress to stomach cancer following the Correa's cascade. The current treatment regimen is H. pylori eradication, yet evidence is lacking that this treatment is effective on later stages of AG especially gastric gland atrophy. Here, using AG mouse model, patient samples, gastric organoids, and lineage tracing, this study unraveled gastric stem cell (GSC) defect as a crucial pathogenic factor in AG in mouse and human. Moreover, a natural peptide is isolated from a traditional Chinese medicine that activated GSCs to regenerate gastric epithelia in experimental AG models and revitalized the atrophic gastric organoids derived from patients. It is further shown that the peptide exerts its functions by stabilizing the EGF-EGFR complex and specifically activating the downstream ERK and Stat1 signaling. Overall, these findings advance the understanding of AG pathogenesis and open a new avenue for AG treatment.

Gastric cancer presents a formidable challenge, marked by its debilitating nature and often dire prognosis. Emerging evidence underscores the pivotal role of tumor stem cells in exacerbating treatment resistance and fueling disease recurrence in gastric cancer. Thus, the identification of genes contributing to tumor stemness assumes paramount importance. Employing a comprehensive approach encompassing ssGSEA, WGCNA, and various machine learning algorithms, this study endeavors to delineate tumor stemness key genes (TSKGs). Subsequently, these genes were harnessed to construct a prognostic model, termed the Tumor Stemness Risk Genes Prognostic Model (TSRGPM). Through PCA, Cox regression analysis and ROC curve analysis, the efficacy of Tumor Stemness Risk Scores (TSRS) in stratifying patient risk profiles was underscored, affirming its ability as an independent prognostic indicator. Notably, the TSRS exhibited a significant correlation with lymph node metastasis in gastric cancer. Furthermore, leveraging algorithms such as CIBERSORT to dissect immune infiltration patterns revealed a notable association between TSRS and monocytes and other cell. Subsequent scrutiny of tumor stemness risk genes (TSRGs) culminated in the identification of CDC25A for detailed investigation. Bioinformatics analyses unveil CDC25A's implication in driving the malignant phenotype of tumors, with a discernible impact on cell proliferation and DNA replication in gastric cancer. Noteworthy validation through in vitro experiments corroborated the bioinformatics findings, elucidating the pivotal role of CDC25A expression in modulating tumor stemness in gastric cancer. In summation, the established and validated TSRGPM holds promise in prognostication and delineation of potential therapeutic targets, thus heralding a pivotal stride towards personalized management of this malignancy.

Endoplasmic reticulum (ER) stress and the adaptive response that follows, termed the unfolded protein response (UPR), are crucial molecular mechanisms to maintain cellular integrity by safeguarding proper protein synthesis. Next to being important in protein homeostasis, the UPR is intricate in cell fate decisions such as proliferation, differentiation, and stemness. In the intestine, stem cells are critical in governing epithelial homeostasis and they are the cell of origin of gastrointestinal malignancies. In this review, we will discuss the role of ER stress and the UPR in the gastrointestinal tract, focusing on stem cells and carcinogenesis. Insights in mechanisms that connect ER stress and UPR with stemness and carcinogenesis may broaden our understanding in the development of cancer throughout the gastrointestinal tract and how we can exploit these mechanisms to target these malignancies.

Gastric cancer (GC) contains subpopulations of cancer stem cells (CSCs), which are described as the main contributors in tumor initiation and metastasis. It is necessary to clarify the molecular mechanism underlying CSCs phenotype and develop novel biomarkers and therapeutic targets for gastric cancer. Here, we show that POLQ positively regulates stem cell-like characteristics of gastric cancer cells, knockdown of POLQ suppressed the stemness of GC cells in vitro and in vivo. Further mechanistic studies revealed that POLQ knockdown could downregulate the expression of dihydroorotate dehydrogenase (DHODH). DHODH overexpression rescued the reduced stemness resulted by POLQ knockdown. Furthermore, we found that POLQ expression correlated with resistance to ferroptosis, and POLQ inhibition renders gastric cancer cells more vulnerable to ferroptosis. Further investigation revealed that POLQ regulated DHODH expression via the transcription factors E2F4, thereby regulating ferroptosis resistance and stemness of gastric cancer cells. Given the importance of POLQ in stemness and ferroptosis resistance of GC, we further evaluated the therapeutic potential of POLQ inhibitor novobiocin, the results show that novobiocin attenuates the stemness of GC cells and increased ferroptosis sensitivity. Moreover, the combination of POLQ inhibitor and ferroptosis inducer synergistically suppressed MGC-803 xenograft tumor growth and diminished metastasis. Our results identify a POLQ-mediated stemness and ferroptosis defense mechanism and provide a new therapeutic strategy for gastric cancer.

Diffuse-type gastric adenocarcinoma (DGAC) is a deadly cancer often diagnosed late and resistant to treatment. While hereditary DGAC is linked to CDH1 mutations, the role of CDH1/E-cadherin inactivation in sporadic DGAC tumorigenesis remains elusive. We discovered CDH1 inactivation in a subset of DGAC patient tumors. Analyzing single-cell transcriptomes in malignant ascites, we identified two DGAC subtypes: DGAC1 (CDH1 loss) and DGAC2 (lacking immune response). DGAC1 displayed distinct molecular signatures, activated DGAC-related pathways, and an abundance of exhausted T cells in ascites. Genetically engineered murine gastric organoids showed that Cdh1 knock-out (KO), KrasG12D, Trp53 KO (EKP) accelerates tumorigenesis with immune evasion compared with KrasG12D, Trp53 KO (KP). We also identified EZH2 as a key mediator promoting CDH1 loss-associated DGAC tumorigenesis. These findings highlight DGAC's molecular diversity and potential for personalized treatment in CDH1-inactivated patients.

The cancer stem cell model hopes to explain solid tumour carcinogenesis, tumour progression and treatment failure in cancers. However, the cancer stem cell model has led to minimal clinical translation to cancer stem cell biomarkers and targeted therapies in solid tumours. Many reasons underlie the challenges, one being the imperfect understanding of the cancer stem cell model. This review hopes to spur further research into clinically translatable cancer stem cell biomarkers through first defining cancer stem cells and their associated models. With a better understanding of these models there would be a development of more accurate biomarkers. Making the clinical translation of biomarkers into diagnostic tools and therapeutic agents more feasible.

Intestinal metaplasia (IM) is a pre-malignant condition of the gastric mucosa associated with increased gastric cancer (GC) risk. Analyzing 1,256 gastric samples (1,152 IMs) across 692 subjects from a prospective 10-year study, we identify 26 IM driver genes in diverse pathways including chromatin regulation (ARID1A) and intestinal homeostasis (SOX9). Single-cell and spatial profiles highlight changes in tissue ecology and IM lineage heterogeneity, including an intestinal stem-cell dominant cellular compartment linked to early malignancy. Expanded transcriptome profiling reveals expression-based molecular subtypes of IM associated with incomplete histology, antral/intestinal cell types, ARID1A mutations, inflammation, and microbial communities normally associated with the healthy oral tract. We demonstrate that combined clinical-genomic models outperform clinical-only models in predicting IMs likely to transform to GC. By highlighting strategies for accurately identifying IM patients at high GC risk and a role for microbial dysbiosis in IM progression, our results raise opportunities for GC precision prevention and interception.

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).

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.

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.

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.

The extrahepatic branches of the biliary tree have glands that connect to the surface epithelium through narrow pits. The duct epithelia undergo homeostatic renewal, yet the identity and multiplicity of cells that maintain this tissue is unknown. Using marker-free and targeted clonal fate mapping in mice, we provide evidence that the extrahepatic bile duct is compartmentalized. Pit cholangiocytes of extramural glands renewed the surface epithelium, whereas basally oriented cholangiocytes maintained the gland itself. In contrast, basally positioned cholangiocytes replenished the surface epithelium in mural glands. Single-cell sequencing identified genes enriched in the base and surface epithelial populations, with trajectory analysis showing graded gene expression between these compartments. Epithelia were plastic, changing cellular identity upon fasting and refeeding. Gain of canonical Wnt signaling caused basal cell expansion, gastric chief cell marker expression, and a decrease in surface epithelial markers. Our results identify the cellular hierarchy governing extrahepatic biliary epithelial renewal.

PDGFRA-expressing mesenchyme supports intestinal stem cells. Stomach epithelia have related niche dependencies, but their enabling mesenchymal cell populations are unknown, in part because previous studies pooled the gastric antrum and corpus. Our high-resolution imaging, transcriptional profiling, and organoid assays identify regional subpopulations and supportive capacities of purified mouse corpus and antral PDGFRA+ cells. Sub-epithelial PDGFRAHi myofibroblasts are principal sources of BMP ligands and two molecularly distinct pools distribute asymmetrically along antral glands but together fail to support epithelial growth in vitro. In contrast, PDGFRALo CD55+ cells strategically positioned beneath gastric glands promote epithelial expansion in the absence of other cells or factors. This population encompasses a small fraction expressing the BMP antagonist Grem1. Although Grem1+ cell ablation in vivo impairs intestinal stem cells, gastric stem cells are spared, implying that CD55+ cell activity in epithelial self-renewal derives from other subpopulations. Our findings shed light on spatial, molecular, and functional organization of gastric mesenchyme and the spectrum of signaling sources for epithelial support.

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.

Gastric cancer (GC) stem cells play an important role in GC progression. Circular RNAs (circRNAs) act as microRNA (miRNA) sponges and inhibit the biological function of miRNAs in GC cytoplasm. MiRNAs also participate in GC progress. circ_0051246 was shown to be associated with miR-375 after analyzing GC microarray data GSE78091 and GSE83521. The oncoprotein Yes-associated protein 1 (YAP1) is targeted by miR-375 and can be inactivated via the Hippo tumor suppressor pathway. Due to insufficient research on circ_0051246, this study aimed to investigate its relationship with miR-375 and YAP1 in cancer stem cells (CSCs).

SGC-7901 CSCs were used to establish knockdown/overexpression models of circ_0051246, miR-375, and YAP1. Malignant phenotypes of CSCs were assessed using Cell Counting Kit 8, colony/sphere formation, 5-Ethynyl-2'-deoxyuridine assay, flow cytometry, Transwell, and wound healing assays. To detect the interactions between circ_0051246, miR-375, and YAP1 in CSCs, a dual-luciferase reporter assay and fluorescence in situ hybridization were performed. In addition, 24 BALB/c nude mice were used to establish orthotopic xenograft tumor models. Four groups of mice were injected with CSCs (1 × 106 cells/100 µL) with circ_0051246 knockdown, miR-375 overexpression, or their respective control cells, and tumor progression and gene expression were observed by hematoxylin-eosin staining, immunohistochemistry. Western blot and quantitative real-time PCR were utilized to examine protein and gene expression, respectively.

Circ_0051246 silencing reduced viability, promoted apoptosis, and inhibited proliferation, migration and invasion of CSCs. The functional effects of miR-375 mimics were comparable to those of circ_0051246 knockdown; however, the opposite was observed after miR-375 inhibitors treatment of CSCs. Furthermore, circ_0051246-overexpression antagonized the miR-375 mimics' effects on CSCs. Additionally, YAP1 overexpression promoted CSC features, such as self-renewal, migration, and invasion, inhibited apoptosis and E-cadherin levels, and upregulated the expression of N-cadherin, vimentin, YAP1, neurogenic locus notch homolog protein 1, and jagged canonical notch ligand 1. Conversely, YAP1-silenced produced the opposite effect. Moreover, miR-375 treatment antagonized the malignant effects of YAP1 overexpression in CSCs. Importantly, circ_0051246 knockdown and miR-375 activation suppressed CSC tumorigenicity in vivo.

This study highlights the promotion of circ_0051246-miR-375-YAP1 axis activation in GC progression and provides a scientific basis for research on the molecular mechanism of CSCs.