Single-cell transcriptomics uncovers EGFR signaling-mediated gastric progenitor cell differentiation in stomach homeostasis

Organoids in gastrointestinal diseases: from bench to clinic

The etiology of gastrointestinal (GI) diseases is intricate and multifactorial, encompassing complex interactions between genetic predisposition and gut microbiota. The cell fate change, immune function regulation, and microenvironment composition in diseased tissues are governed by microorganisms and mutated genes either independently or through synergistic interactions. A comprehensive understanding of GI disease etiology is imperative for developing precise prevention and treatment strategies. However, the existing models used for studying the microenvironment in GI diseases-whether cancer cell lines or mouse models-exhibit significant limitations, which leads to the prosperity of organoids models. This review first describes the development history of organoids models, followed by a detailed demonstration of organoids application from bench to clinic. As for bench utilization, we present a layer-by-layer elucidation of organoid simulation on host-microbial interactions, as well as the application in molecular mechanism analysis. As for clinical adhibition, we provide a generalized interpretation of organoid application in GI disease simulation from inflammatory disorders to malignancy diseases, as well as in GI disease treatment including drug screening, immunotherapy, and microbial-targeting and screening treatment. This review draws a comprehensive and systematical depiction of organoids models, providing a novel insight into the utilization of organoids models from bench to clinic.

Amphiregulin Switches Progenitor Cell Fate for Lineage Commitment During Gastric Mucosal Regeneration

BACKGROUND & AIMS

Isthmic progenitors, tissue-specific stem cells in the stomach corpus, maintain mucosal homeostasis by balancing between proliferation and differentiation to gastric epithelial lineages. The progenitor cells rapidly adopt an active state in response to mucosal injury. However, it remains unclear how the isthmic progenitor cell niche is controlled during the regeneration of damaged epithelium.

METHODS

We recapitulated tissue recovery process after acute mucosal injury in the mouse stomach. Bromodeoxyuridine incorporation was used to trace newly generated cells during the injury and recovery phases. To define the epithelial lineage commitment process during recovery, we performed single-cell RNA-sequencing on epithelial cells from the mouse stomachs. We validated the effects of amphiregulin (AREG) on mucosal recovery, using recombinant AREG treatment or AREG-deficient mice.

RESULTS

We determined that an epidermal growth factor receptor ligand, AREG, can control progenitor cell lineage commitment. Based on the identification of lineage-committed subpopulations in the corpus epithelium through single-cell RNA-sequencing and bromodeoxyuridine incorporation, we showed that isthmic progenitors mainly transition into short-lived surface cell lineages but are less frequently committed to long-lived parietal cell lineages in homeostasis. However, mucosal regeneration after damage directs the lineage commitment of isthmic progenitors towards parietal cell lineages. During recovery, AREG treatment promoted repopulation with parietal cells, while suppressing surface cell commitment of progenitors. In contrast, transforming growth factor-α did not alter parietal cell regeneration, but did induce expansion of surface cell populations. AREG deficiency impairs parietal cell regeneration but increases surface cell commitment.

CONCLUSIONS

These data demonstrate that different epidermal growth factor receptor ligands can distinctly regulate isthmic progenitor-driven mucosal regeneration and lineage commitment.

Highlights of how single-cell analyses are illuminating differentiation and disease in the gastric corpus

Single-cell RNA-sequencing (scRNA-seq) has emerged as a powerful technique to identify novel cell markers, developmental trajectories, and transcriptional changes during cell differentiation and disease onset and progression. In this review, we highlight recent scRNA-seq studies of the gastric corpus in both human and murine systems that have provided insight into gastric organogenesis, identified novel markers for the various gastric lineages during development and in adults, and revealed transcriptional changes during regeneration and tumorigenesis. Overall, by elucidating transcriptional states and fluctuations at the cellular level in healthy and disease contexts, scRNA-seq may lead to better, more personalized clinical treatments for disease progression.

Insights into the inhibition of stomach cancer MKN45 cell growth by Poria cocos ethanol-soluble extract based on MAPK/PI3K signaling pathways and components cell fishing

ETHNOPHARMACOLOGICAL RELEVANCE

Poria cocos F.A. Wolf is an edible fungus with forming sclerotia, which has the effects of promoting diuresis, exuding dampness, invigorating the spleen, and regulating the stomach. P. cocos has a high application in the clinic of traditional Chinese medicine, and some studies have indicated that P. cocos has a good effect on tumor diseases. According to ancient records and modern studies, P. cocos wine offers beneficial effects in terms of strengthening tendons and bones and anti-tumor effects.

AIM OF THE STUDY

To understand the substance composition of P. cocos ethanol-soluble extract (PESE) and then further study the effect and potential mechanism of PESE components on gastric cancer.

MATERIALS AND METHODS

In vitro and in vivo experiments were performed to detect the cell activity and apoptotic condition. Differential expression analysis and pathway enrichment were performed based on transcriptomics and were verified by real-time polymerase chain reaction and western blotting. The mice of the stomach cancer tumor model were randomly categorized into three groups. The weight and tumor volume of the mice were measured, and the pathological characteristics of tumor tissue and immunohistochemical changes were determined. Then, the main active components of PESE were detected by MKN45 cell fishing.

RESULTS

In vitro experiments showed that PESE inhibited the proliferation of MKN45 cells, but it did not induce apoptosis. Based on the transcriptome and western blotting results, the inhibition of MKN45 proliferation by PESE may be influenced by mitogen-activated protein kinase (MAPK) and phosphoinositide-3-kinase-protein kinase B (PI3K-Akt) signaling pathways. In vivo experiments showed that PESE inhibited tumor growth in mice and caused partial necrosis of tumor cells but had no toxic effect on mice. Cell fishing identified nine triterpenoids of P. cocos as the major active components of PESE.

CONCLUSIONS

The results indicated that PESE has a significant inhibitory effect on stomach cancer, and its mechanism probably commonly affects the MAPK and PI3K-Akt signaling pathways, which could be due to the triterpenoid components.

Transforming Growth Factor α Evokes Aromatase Expression in Gastric Parietal Cells during Rat Postnatal Development

Estrogen, well known as a female hormone, is synthesized primarily by ovarian aromatase. However, extra-glandular tissues also express aromatase and produce estrogen. It is noteworthy that aromatase in gastric parietal cells begins expression around 20 days after birth and continues secreting considerable amounts of estrogen into the portal vein throughout life, supplying it to the liver. Estrogen, which is secreted from the stomach, is speculated to play a monitoring role in blood triglyceride, and its importance is expected to increase. Nevertheless, the regulatory mechanisms of the aromatase expression remain unclear. This study investigated the influence of transforming growth factor α (TGFα) on gastric aromatase expression during postnatal development. The administration of TGFα (50 μg/kg BW) to male Wistar rats in the weaning period resulted in enhanced aromatase expression and increased phosphorylated ERK1+2 in the gastric mucosa. By contrast, administration of AG1478 (5 mg/kg BW), a protein tyrosine kinase inhibitor with high selectivity for the epidermal growth factor receptor and acting as an antagonist of TGFα, led to the suppression of aromatase expression. In fact, TGFα expression in the gastric fundic gland isthmus began around 20 days after birth in normal rats as did that of aromatase, which indicates that TGFα might induce the expression of aromatase in the parietal cells concomitantly.

Covalent inhibition of epidermal growth factor receptor using a long-lived iridium(III)-afatinib probe

The overexpression and overactivation of epidermal growth factor receptor (EGFR) are frequently observed in human cancers, including squamous cell carcinoma and adenocarcinoma. In this study, a covalent EGFR probe was developed by conjugating afatinib to an iridium(III) scaffold. Complex 1 showed enhanced luminescence in living epidermoid squamous carcinoma A431 cells compared to other cell lines, via engaging EGFR as confirmed via CETSA and knockdown experiments. Moreover, complex 1 inhibited downstream targets of EGFR in cellulo with repression persisting after removal of the complex, indicating an irreversible mode of inhibition. Finally, complex 1 showed potent antiproliferative activity against A431 cells with comparable potency to afatinib alone. To our knowledge, complex 1 is the first EGFR covalent inhibitor based on an iridium scaffold reported in the literature, with the potential to be further explored as a theranostic agent in the future.

ROR2 regulates cellular plasticity in pancreatic neoplasia and adenocarcinoma

Cellular plasticity is a hallmark of pancreatic ductal adenocarcinoma (PDAC) starting from the conversion of normal cells into precancerous lesions to the progression of carcinoma subtypes associated with aggressiveness and therapeutic response. We discovered that normal acinar cell differentiation, maintained by the transcription factor Pdx1, suppresses a broad gastric cell identity that is maintained in metaplasia, neoplasia, and the classical subtype of PDAC in mouse and human. We have identified the receptor tyrosine kinase Ror2 as marker of a gastric metaplasia (SPEM)-like identity in the pancreas. Ablation of Ror2 in a mouse model of pancreatic tumorigenesis promoted a switch to a gastric pit cell identity that largely persisted through progression to the classical subtype of PDAC. In both human and mouse pancreatic cancer, ROR2 activity continued to antagonize the gastric pit cell identity, strongly promoting an epithelial to mesenchymal transition, conferring resistance to KRAS inhibition, and vulnerability to AKT inhibition.

Protective effect of Amauroderma rugosum ethanol extract and its primary bioactive compound, ergosterol, against acute gastric ulcers based on LXR-mediated gastric mucus secretions

BACKGROUND

Amauroderma rugosum (Blume & T. Nees) Torrend (Ganodermataceae) is an edible mushroom with a wide range of medicinal values. Our previous publication demonstrated the therapeutic effects of the water extract of A. rugosum (WEA) against gastric ulcers. However, the protective effects of the ethanol extract of A. rugosum (EEA) on gastric mucosa and its major active constituents have not yet been elucidated.

PURPOSE

This study aims to evaluate the gastroprotective effects and underlying mechanisms of EEA and its fat-soluble constituent, ergosterol, in acute gastric ulcers.

STUDY DESIGN AND METHOD

SD rats were pre-treated with EEA (50, 100, and 200 mg/kg) or ergosterol (5, 10, and 20 mg/kg), and acute gastric ulcer models were constructed using ethanol, gastric mucus secretion inhibitor (indomethacin) or pyloric-ligation. The gastric ulcer area, histological structure alterations (H&E staining), and mucus secretion (AB-PAS staining) were recorded. Additionally, Q-PCR, western blotting, immunohistochemistry, ELISA, molecular docking, molecular dynamics simulations, MM-GBSA analysis, and surface plasmon resonance assay (SPR) were used to investigate the underlying mechanisms of the gastroprotective effect.

RESULT

Compared with WEA, which primarily exerts its anti-ulcer effects by inhibiting inflammation, EEA containing fat-soluble molecules showed more potent gastroprotective effect through the promotion of gastric mucus secretion, as the anti-ulcer activity was partly blocked by indomethacin. Meanwhile, EEA exhibited anti-inflammatory effects by suppressing the production of IL-6, IL-1β, TNF-α, and NO, thereby inhibiting the MAPK pathway. Significantly, ergosterol (20 mg/kg), the bioactive water-insoluble compound in EEA, exhibited a gastroprotective effect comparable to that of lansoprazole (30 mg/kg). The promotion of gastric mucus secretion contributed to the effects of ergosterol, as indomethacin can completely block it. The upregulations of COX1-PGE2 and C-fos, an activator protein 1 (AP-1) transcription factor, were observed after the ergosterol treatment. Ergosterol acted as an LXRβ agonist via van der Waals binding and stabilizing the LXRβ protein without compromising its flexibility, thereby inducing the upregulation of AP-1 and COX-1.

CONCLUSION

EEA and its primary bioactive compound, ergosterol, exert anti-ulcer effects by promoting gastric mucus secretion through the LXRβ/C-fos/COX-1/PGE2 pathway.

Role of PDGFRA+ cells and a CD55+ PDGFRALo fraction in the gastric mesenchymal niche

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.