Prostaglandin E2 Activates YAP and a Positive-Signaling Loop to Promote Colon Regeneration After Colitis but Also Carcinogenesis in Mice

Prostaglandin E2 Induces YAP1 and Agrin Through EP4 in Neonatally-Derived Islet-1+ Stem Cells

Prostaglandin E2 (PGE2) has recently gained attention in the field of regenerative medicine because of the beneficial effects of this molecule on stem cell proliferation and migration. Furthermore, PGE2 has the ability to mitigate immune rejection and fibrosis. In the colon and kidney, PGE2 induces YAP1, a transcription factor critical for cardiac regeneration. Establishing a similar connection in stem cells that can be transplanted in the heart could lead to the development of more effective therapeutics. In this report, we identify the effects of PGE2 on neonatal Islet-1+ stem cells. These stem cells synthesize PGE2, which functions by stimulating the transcription of the extracellular matrix protein Agrin. Agrin upregulates YAP1. Consequently, both YAP1 and Agrin are induced by PGE2 treatment. Our study shows that PGE2 upregulated the expression of both YAP1 and Agrin in Islet-1+ stem cells through the EP4 receptor and stimulated proliferation using the same mechanisms. PGE2 administration further elevated the expression of stemness markers and the matrix metalloproteinase MMP9, a key regulator of remodeling in the extracellular matrix post-injury. The expression of PGE2 in neonatal Islet-1+ cells is a factor which contributes to improving the functional efficacy of these cells for cardiac repair.

Navigating the Landscape of Intestinal Regeneration: A Spotlight on Quiescence Regulation and Fetal Reprogramming

Tissue-specific adult stem cells are pivotal in maintaining tissue homeostasis, especially in the rapidly renewing intestinal epithelium. At the heart of this process are leucine-rich repeat-containing G protein-coupled receptor 5-expressing crypt base columnar cells (CBCs) that differentiate into various intestinal epithelial cells. However, while these CBCs are vital for tissue turnover, they are vulnerable to cytotoxic agents. Recent advances indicate that alternative stem cell sources drive the epithelial regeneration post-injury. Techniques like lineage tracing and single-cell RNA sequencing, combined with in vitro organoid systems, highlight the remarkable cellular adaptability of the intestinal epithelium during repair. These regenerative responses are mediated by the reactivation of conserved stem cells, predominantly quiescent stem cells and revival stem cells. With focus on these cells, this review unpacks underlying mechanisms governing intestinal regeneration and explores their potential clinical applications.

Amphiregulin orchestrates the paracrine immune-suppressive function of amniotic-derived cells through its interplay with COX-2/PGE2/EP4 axis

The paracrine crosstalk between amniotic-derived membranes (AMs)/epithelial cells (AECs) and immune cells is pivotal in tissue healing following inflammation. Despite evidence collected to date, gaps in understanding the underlying molecular mechanisms have hindered clinical applications. The present study represents a significant step forward demonstrating that amphiregulin (AREG) orchestrates the native immunomodulatory functions of amniotic derivatives via the COX-2/PGE2/EP4 axis. The results highlight the immunosuppressive efficacy of PGE2-dependent AREG release, dampening PBMCs' activation, and NFAT pathway in Jurkat reporter cells via TGF-β signaling. Moreover, AREG emerges as a key protein mediator by attenuating acute inflammatory response in Tg(lysC:DsRed2) zebrafish larvae. Notably, the interplay of diverse COX-2/PGE2 pathway activators enables AM/AEC to adapt rapidly to external stimuli (LPS and/or stretching) through a responsive positive feedback loop on the AREG/EGFR axis. These findings offer valuable insights for developing innovative cell-free therapies leveraging the potential of amniotic derivatives in immune-mediated diseases and regenerative medicine.

Insights gained from computational modeling of YAP/TAZ signaling for cellular mechanotransduction

YAP/TAZ signaling pathway is regulated by a multiplicity of feedback loops, crosstalk with other pathways, and both mechanical and biochemical stimuli. Computational modeling serves as a powerful tool to unravel how these different factors can regulate YAP/TAZ, emphasizing biophysical modeling as an indispensable tool for deciphering mechanotransduction and its regulation of cell fate. We provide a critical review of the current state-of-the-art of computational models focused on YAP/TAZ signaling.

In silico screening and in vivo experimental validation of 15-PGDH inhibitors from traditional Chinese medicine promoting liver regeneration

The enzyme 15-hydroxyprostaglandin dehydrogenase (15-PGDH), which acts as a negative regulator of prostaglandin E2 (PGE2) levels and activity, represents a promising pharmacological target for promoting liver regeneration. In this study, we collected data on 15-PGDH homologous family proteins, their inhibitors, and traditional Chinese medicine (TCM) compounds. Leveraging machine learning and molecular docking techniques, we constructed a prediction model for virtual screening of 15-PGDH inhibitors from TCM compound library and successfully screened genistein as a potential 15-PGDH inhibitor. Through further validation, it was discovered that genistein considerably enhances liver regeneration by inhibiting 15-PGDH, resulting in a significant increase in the PGE2 level. Genistein's effectiveness suggests its potential as a novel therapeutic agent for liver diseases, highlighting this study's contribution to expanding the clinical applications of TCM.

Activation of fetal-like molecular programs during regeneration in the intestine and beyond

Tissue regeneration after damage is generally thought to involve the mobilization of adult stem cells that divide and differentiate into progressively specialized progeny. However, recent studies indicate that tissue regeneration can be accompanied by reversion to a fetal-like state. During this process, cells at the injury site reactivate programs that operate during fetal development but are typically absent in adult homeostasis. Here, we summarize our current understanding of the molecular signals and epigenetic mediators that orchestrate "fetal-like reversion" during intestinal regeneration. We also explore evidence for this phenomenon in other organs and species and highlight open questions that merit future examination.

Inhibition of YAP/TAZ pathway contributes to the cytotoxicity of silibinin in MCF-7 and MDA-MB-231 human breast cancer cells

Breast cancer is one of the most common cancers threatening women's health. Our previous study found that silibinin induced the death of MCF-7 and MDA-MB-231 human breast cancer cells. We noticed that silibinin-induced cell damage was accompanied by morphological changes, including the increased cell aspect ratio (cell length/width) and decreased cell area. Besides, the cytoskeleton is also destroyed in cells treated with silibinin. YAP/TAZ, a mechanical signal sensor interacted with extracellular pressure, cell adhesion area and cytoskeleton, is also closely associated with cell survival, proliferation and migration. Thus, the involvement of YAP/TAZ in the cytotoxicity of silibinin in breast cancer cells has attracted our interests. Excitingly, we find that silibinin inhibits the nuclear translocation of YAP/TAZ in MCF-7 and MDA-MB-231 cells, and reduces the mRNA expressions of YAP/TAZ target genes, ACVR1, MnSOD and ANKRD. More importantly, expression of YAP1 gene is negatively correlated with the survival of the patients with breast cancers. Molecular docking analysis reveals high probabilities for binding of silibinin to the proteins in the YAP pathways. DARTS and CETSA results confirm the binding abilities of silibinin to YAP and LATS. Inhibiting YAP pathway either by addition of verteporfin, an inhibitor of YAP/TAZ-TEAD, or by transfection of si-RNAs targeting YAP or TAZ further enhances silibinin-induced cell damage. While enhancing YAP activity by silencing LATS1/2 or overexpressing YAPS127/397A, an active form of YAP, attenuates silibinin-induced cell damage. These findings demonstrate that inhibition of the YAP/TAZ pathway contributes to cytotoxicity of silibinin in breast cancers, shedding lights on YAP/TAZ-targeted cancer therapies.

YAP upregulates AMPKα1 to induce cancer cell senescence

Yes-associated protein (YAP)-a major effector protein of the Hippo pathway- regulates cell proliferation, differentiation, apoptosis, and senescence. Amp-activated protein kinase (AMPK) is a key sensor that monitors cellular nutrient supply and energy status. Although YAP and AMPK are considered to regulate cellular senescence, it is still unclear whether AMPK is involved in YAP-regulated cellular senescence. Here, we found that YAP promoted AMPKα1 aggregation and localization around mitochondria by co-transfecting CFP-YAP and YFP-AMPKα1 plasmids. Subsequent live cell fluorescence resonance energy transfer (FRET) assay did not exhibit direct interaction between YAP and AMPKα1. FRET, Co-immunoprecipitation, and western blot experiments revealed that YAP directly bound to TEAD, enhancing the expression of AMPKα1 and p-AMPKα. Treatment with verteporfin inhibited YAP's binding to TEAD and reversed the elevated expression of AMPKα1 in the cells overexpressing CFP-YAP. Verteporfin also reduced the proportion of AMPKα1 puncta in the cells co-expressing CFP-YAP and YFP-AMPKα1. In addition, the AMPKα1 puncta were demonstrated to inhibit cell viability, autophagy, and proliferation, and ultimately promote cell senescence. In conclusion, YAP binds to TEAD to upregulate AMPKα1 and promotes the formation of AMPKα1 puncta around mitochondria under the condition of co-expression of CFP-YAP and YFP-AMPKα1, in which AMPKα1 puncta lead to cellular senescence.

GRK2 mediated degradation of SAV1 initiates hyperplasia of fibroblast-like synoviocytes in rheumatoid arthritis

Hyperplasia and migration of fibroblast-like synoviocytes (FLSs) are the key drivers in the pathogenesis of rheumatoid arthritis (RA) and joint destruction. Abundant Yes-associated protein (YAP), which is a powerful transcription co-activator for proliferative genes, was observed in the nucleus of inflammatory FLSs with unknown upstream mechanisms. Using Gene Expression Omnibus database analysis, it was found that Salvador homolog-1 (SAV1), the pivotal negative regulator of the Hippo-YAP pathway, was slightly downregulated in RA synovium. However, SAV1 protein expression is extremely reduced. Subsequently, it was revealed that SAV1 is phosphorylated, ubiquitinated, and degraded by interacting with an important serine-threonine kinase, G protein-coupled receptor (GPCR) kinase 2 (GRK2), which was predominately upregulated by GPCR activation induced by ligands such as prostaglandin E2 (PGE2) in RA. This process further contributes to the decreased phosphorylation, nuclear translocation, and transcriptional potency of YAP, and leads to aberrant FLSs proliferation. Genetic depletion of GRK2 or inhibition of GRK2 by paroxetine rescued SAV1 expression and restored YAP phosphorylation and finally inhibited RA FLSs proliferation and migration. Similarly, paroxetine treatment effectively reduced the abnormal proliferation of FLSs in a rat model of collagen-induced arthritis which was accompanied by a significant improvement in clinical manifestations. Collectively, these results elucidate the significance of GRK2 regulation of Hippo-YAP signaling in FLSs proliferation and migration and the potential application of GRK2 inhibition in the treatment of FLSs-driven joint destruction in RA.

Immune cell-derived signals governing epithelial phenotypes in homeostasis and inflammation

The intestinal epithelium fulfills important physiological functions and forms a physical barrier to the intestinal lumen. Barrier function is regulated by several pathways, and its impairment contributes to the pathogenesis of inflammatory bowel disease (IBD), a chronic inflammatory condition affecting more than seven million people worldwide. Current treatment options specifically target inflammatory mediators and have led to improvement of clinical outcomes; however, a significant proportion of patients experience treatment failure. Pro-repair effects of inflammatory mediators on the epithelium are emerging. In this review we summarize current knowledge on involved epithelial pathways, identify open questions, and put recent findings into clinical perspective, and pro-repair effects. A detailed understanding of epithelial pathways integrating mucosal stimuli in homeostasis and inflammation is crucial for the development of novel, more targeted therapies.

Role of Hippo pathway dysregulation from gastrointestinal premalignant lesions to cancer

BACKGROUND

First identified in Drosophila melanogaster, the Hippo pathway is considered a major regulatory cascade controlling tissue homeostasis and organ development. Hippo signaling components include kinases whose activity regulates YAP and TAZ final effectors. In response to upstream stimuli, YAP and TAZ control transcriptional programs involved in cell proliferation, cytoskeletal reorganization and stemness.

MAIN TEXT

While fine tuning of Hippo cascade components is essential for maintaining the balance between proliferative and non-proliferative signals, pathway signaling is frequently dysregulated in gastrointestinal cancers. Also, YAP/TAZ aberrant activation has been described in conditions characterized by chronic inflammation that precede cancer development, suggesting a role of Hippo effectors in triggering carcinogenesis. In this review, we summarize the architecture of the Hippo pathway and discuss the involvement of signaling cascade unbalances in premalignant lesions of the gastrointestinal tract, providing a focus on the underlying molecular mechanisms.

CONCLUSIONS

The biology of premalignant Hippo signaling dysregulation needs further investigation in order to elucidate the evolutionary trajectories triggering cancer inititation and develop effective early therapeutic strategies targeting the Hippo/YAP pathway.

YAP represses intestinal inflammation through epigenetic silencing of JMJD3

BACKGROUND

Epigenetics plays an important role in the pathogenesis of inflammatory bowel disease (IBD). Some studies have reported that YAP is involved in inflammatory response and can regulate target genes through epigenetic modifications. JMJD3, a histone H3K27me3 demethylase, is associated with some inflammatory diseases. In this study, we investigated the role of YAP in the development of IBD and the underlying epigenetic mechanisms.

RESULTS

YAP expression was significantly increased in both in vitro and in vivo colitis models as well as in patients with IBD. Epithelial-specific knockout of YAP aggravates disease progression in dextran sodium sulfate (DSS)-induced murine colitis. In the TNF-α-activated cellular inflammation model, YAP knockdown significantly increased JMJD3 expression. Coimmunoprecipitation experiments showed that YAP and EZH2 bind to each other, and chromatin immunoprecipitation-PCR (ChIP-PCR) assay indicated that silencing of YAP or EZH2 decreases H3K27me3 enrichment on the promoter of JMJD3. Finally, administration of the JMJD3 pharmacological inhibitor GSK-J4 alleviated the progression of DSS-induced murine colitis.

CONCLUSION

Our findings elucidate an epigenetic mechanism by which YAP inhibits the inflammatory response in colitis through epigenetic silencing of JMJD3 by recruiting EZH2.

Impaired Expression of the Salvador Homolog-1 Gene Is Associated with the Development and Progression of Colorectal Cancer

Salvador homolog-1 (SAV1) is a component of the Hippo pathway that regulates tissue growth and homeostasis by affecting diverse cell processes, including apoptosis, cell division, and differentiation. The aberrant expression of Hippo pathway components has been observed in various human cancers. This study aimed to examine the expression level of the SAV1 gene in colorectal cancer (CRC) and its prognostic value and associations with tumor progression. We obtained matched pairs of tumor tissue and non-cancerous mucosa of the large intestine from 94 CRC patients as well as 40 colon biopsies of healthy subjects collected during screening colonoscopy. The tissue samples and CRC cell lines were quantified for SAV1 mRNA levels using the quantitative polymerase chain reaction method, while SAV1 protein expression was estimated in the paired tissues of CRC patients using immunohistochemistry. The average level of SAV1 mRNA was decreased in 93.6% of the tumor tissues compared to the corresponding non-cancerous tissues and biopsies of healthy colon mucosa. A downregulated expression of SAV1 mRNA was also noted in the CRC cell lines. Although the average SAV1 immunoreactivity was increased in the CRC samples compared to the non-cancerous tissues, a decreased immunoreactivity of the SAV1 protein in the tumor specimens was associated with lymph node involvement and higher TNM disease stage and histological grade. The results of our study suggest that the impaired expression of SAV1 is involved in CRC progression.

ENO1 promotes liver carcinogenesis through YAP1-dependent arachidonic acid metabolism

Enolase 1 (ENO1) is a glycolytic enzyme that plays essential roles in various pathological activities including cancer development. However, the mechanisms underlying ENO1-contributed tumorigenesis are not well explained. Here, we uncover that ENO1, as an RNA-binding protein, binds to the cytosine-uracil-guanine-rich elements of YAP1 messenger RNA to promote its translation. ENO1 and YAP1 positively regulate alternative arachidonic acid (AA) metabolism by inverse regulation of PLCB1 and HPGD (15-hydroxyprostaglandin dehydrogenase). The YAP1/PLCB1/HPGD axis-mediated activation of AA metabolism and subsequent accumulation of prostaglandin E2 (PGE2) are responsible for ENO1-mediated cancer progression, which can be retarded by aspirin. Finally, aberrant activation of ENO1/YAP1/PLCB1 and decreased HPGD expression in clinical hepatocellular carcinoma samples indicate a potential correlation between ENO1-regulated AA metabolism and cancer development. These findings underline a new function of ENO1 in regulating AA metabolism and tumorigenesis, suggesting a therapeutic potential for aspirin in patients with liver cancer with aberrant expression of ENO1 or YAP1.

Downregulation of 15-PGDH enhances MASH-HCC development via fatty acid-induced T-cell exhaustion

Background & Aims

Hepatocellular carcinoma (HCC) mainly develops from chronic hepatitis. Metabolic dysfunction-associated steatohepatitis (MASH) has gradually become the main pathogenic factor for HCC given the rising incidence of obesity and metabolic diseases. 15-Hydroxyprostaglandin dehydrogenase (15-PGDH) degrades prostaglandin 2 (PGE2), which is known to exacerbate inflammatory responses. However, the role of PGE2 accumulation caused by 15-PGDH downregulation in the development of MASH-HCC has not been determined.

Methods

We utilised the steric animal model to establish a MASH-HCC model using wild-type and 15-Pgdh+/- mice to assess the significance of PGE2 accumulation in the development of MASH-HCC. Additionally, we analysed clinical samples obtained from patients with MASH-HCC.

Results

PGE2 accumulation in the tumour microenvironment induced the production of reactive oxygen species in macrophages and the expression of cell growth-related genes and antiapoptotic genes. Conversely, the downregulation of fatty acid metabolism in the background liver promoted lipid accumulation in the tumour microenvironment, causing a decrease in mitochondrial membrane potential and CD8+ T-cell exhaustion, which led to enhanced development of MASH-HCC.

Conclusions

15-PGDH downregulation inactivates immune surveillance by promoting the proliferation of exhausted effector T cells, which enhances hepatocyte survival and proliferation and leads to the development of MASH-HCC.

Impact and implications

The suppression of PGE2-related inflammation and subsequent lipid accumulation leads to a reduction in the severity of MASH and inhibition of subsequent progression toward MASH-HCC.

Partial in vivo reprogramming enables injury-free intestinal regeneration via autonomous Ptgs1 induction

Tissue regeneration after injury involves the dedifferentiation of somatic cells, a natural adaptive reprogramming that leads to the emergence of injury-responsive cells with fetal-like characteristics. However, there is no direct evidence that adaptive reprogramming involves a shared molecular mechanism with direct cellular reprogramming. Here, we induced dedifferentiation of intestinal epithelial cells using OSKM (Oct4, Sox2, Klf4, and c-Myc) in vivo. The OSKM-induced forced dedifferentiation showed similar molecular features of intestinal regeneration, including a transition from homeostatic cell types to injury-responsive-like cell types. These injury-responsive-like cells, sharing gene signatures of revival stem cells and atrophy-induced villus epithelial cells, actively assisted tissue regeneration following damage. In contrast to normal intestinal regeneration involving Ptgs2 induction, the OSKM promotes autonomous production of prostaglandin E2 via epithelial Ptgs1 expression. These results indicate prostaglandin synthesis is a common mechanism for intestinal regeneration but involves a different enzyme when partial reprogramming is applied to the intestinal epithelium.

YAP/TAZ: Molecular pathway and disease therapy

The Yes-associated protein and its transcriptional coactivator with PDZ-binding motif (YAP/TAZ) are two homologous transcriptional coactivators that lie at the center of a key regulatory network of Hippo, Wnt, GPCR, estrogen, mechanical, and metabolism signaling. YAP/TAZ influences the expressions of downstream genes and proteins as well as enzyme activity in metabolic cycles, cell proliferation, inflammatory factor expression, and the transdifferentiation of fibroblasts into myofibroblasts. YAP/TAZ can also be regulated through epigenetic regulation and posttranslational modifications. Consequently, the regulatory function of these mechanisms implicates YAP/TAZ in the pathogenesis of metabolism-related diseases, atherosclerosis, fibrosis, and the delicate equilibrium between cancer progression and organ regeneration. As such, there arises a pressing need for thorough investigation of YAP/TAZ in clinical settings. In this paper, we aim to elucidate the signaling pathways that regulate YAP/TAZ and explore the mechanisms of YAP/TAZ-induce diseases and their potential therapeutic interventions. Furthermore, we summarize the current clinical studies investigating treatments targeting YAP/TAZ. We also address the limitations of existing research on YAP/TAZ and propose future directions for research. In conclusion, this review aims to provide fresh insights into the signaling mediated by YAP/TAZ and identify potential therapeutic targets to present innovative solutions to overcome the challenges associated with YAP/TAZ.

The Hippo Pathway Effectors YAP/TAZ-TEAD Oncoproteins as Emerging Therapeutic Targets in the Tumor Microenvironment

Various cancer cell-associated intrinsic and extrinsic inputs act on YAP/TAZ proteins to mediate the hyperactivation of the TEAD transcription factor-based transcriptome. This YAP/TAZ-TEAD activity can override the growth-limiting Hippo tumor-suppressor pathway that maintains normal tissue homeostasis. Herein, we provide an integrated summary of the contrasting roles of YAP/TAZ during normal tissue homeostasis versus tumor initiation and progression. In addition to upstream factors that regulate YAP/TAZ in the TME, critical insights on the emerging functions of YAP/TAZ in immune suppression and abnormal vasculature development during tumorigenesis are illustrated. Lastly, we discuss the current methods that intervene with the YAP/TAZ-TEAD oncogenic signaling pathway and the emerging applications of combination therapies, gut microbiota, and epigenetic plasticity that could potentiate the efficacy of chemo/immunotherapy as improved cancer therapeutic strategies.

YAP at the progression of inflammation

Yes-associated protein (YAP) is a transcriptional regulator that affects cell proliferation, organ size and tissue development and regeneration, and has therefore, been an important object of study. In recent years, there has been an increasing research focus on YAP in inflammation and immunology, and the role of YAP in the development of inflammation and in immune escape by tumors has been progressively elucidated. Because YAP signaling involves a variety of different signal transduction cascades, the full range of functions in diverse cells and microenvironments remains incompletely understood. In this article, we discuss the complex involvement of YAP in inflammation, the molecular mechanisms through which it exercises pro- and anti-inflammatory effects under different conditions, and the progress achieved in elucidating the functions of YAP in inflammatory diseases. A thorough understanding of YAP signaling in inflammation will provide a foundation for its use as a therapeutic target in inflammatory diseases.

Insights into recent findings and clinical application of YAP and TAZ in cancer

Decades of research have mapped out the basic mechanics of the Hippo pathway. The paralogues Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ), as the central transcription control module of the Hippo pathway, have long been implicated in the progression of various human cancers. The current literature regarding oncogenic YAP and TAZ activities consists mostly of context-specific mechanisms and treatments of human cancers. Furthermore, a growing number of studies demonstrate tumour-suppressor functions of YAP and TAZ. In this Review we aim to synthesize an integrated perspective of the many disparate findings regarding YAP and TAZ in cancer. We then conclude with the various strategies for targeting and treating YAP- and TAZ-dependent cancers.

Targeting Leukemia Inhibitory Factor in Pancreatic Adenocarcinoma

INTRODUCTION

Leukemia Inhibitory Factor (LIF) is a member of the interleukin-6 (IL-6) cytokine family. Known to induce differentiation of myeloid leukemia cells, evidence has accumulated supporting its role in cancer evolution though regulating cell differentiation, renewal, and survival. LIF has recently emerged as a biomarker and therapeutic target for pancreatic ductal adenocarcinoma (PDAC). The first-in-human clinical trial has shown promising safety profile and has suggested a potential role for LIF inhibitor in combination regimen.

AREAS COVERED

Herein, we summarize, discuss, and give an expert opinion on the role of LIF in PDAC promotion, and its potential role as a biomarker and target of anti-cancer therapy. We conducted an exhaustive PubMed search for English-language articles published from January 1, 1970, to August 1, 2022.

EXPERT OPINION

PDAC carries a devastating prognosis for patients, highlighting the need for advancing drug development. The results of the phase 1 trial with MSC-1 demonstrated tolerability and safety but modest efficacy. Future research should focus on investigating LIF targets in combination with current standard-of-care chemotherapy and immunotherapy can be a promising approach. Further, larger multicenter clinical trials are needed to define the use of LIF as a new biomarker in PDAC patients.

Targeting Hippo pathway: A novel strategy for Helicobacter pylori-induced gastric cancer treatment

The Hippo pathway plays an important role in cell proliferation, apoptosis, and differentiation; it is a crucial regulatory pathway in organ development and tumor growth. Infection with Helicobacter pylori (H. pylori) increases the risk of developing gastric cancer. In recent years, significant progress has been made in understanding the mechanisms by which H. pylori infection promotes the development and progression of gastric cancer via the Hippo pathway. Exploring the Hippo pathway molecules may yield new diagnostic and therapeutic targets for H. pylori-induced gastric cancer. The current article reviews the composition and regulatory mechanism of the Hippo pathway, as well as the research progress of the Hippo pathway in the occurrence and development of H. pylori-related gastric cancer, in order to provide a broader perspective for the study and prevention of gastric cancer.

The Role and Mechanism of Action of Mitophagy in Various Liver Diseases

Significance: Liver disease is one of the biggest threats to public health, affecting as much as 5.5 million people worldwide. Mitochondrial dysfunction is associated with various acute and chronic liver diseases. Mitophagy, a selective form of autophagy for damaged/excessive mitochondria, plays a key role either in the pathogenesis or in maintaining hepatic homeostasis in response to various liver diseases. Recent Advances: Significant progress has been achieved to ascertain the causes of liver disease. The conserved pathways for mitochondrial degradation via mitophagy, the deregulation of mitophagy in liver diseases, and pharmacological or genetic maneuvers that alter the mitophagic flux for liver disease treatment have been widely studied but yet to be comprehensively reviewed. Critical Issues: Liver disease is considered a leading cause of mortality globally, causing the heavy burden of disability and the increased health care utilization that needs to be settled urgently. Mitophagy plays an important role in protecting liver from tissue damage to maintain hepatic homeostasis or in pathogenesis of liver disease. Elaborating mitophagy implicated in the pathogenesis of liver disease, as well as potential therapeutic regimens by targeting mitophagy is of great significance for the understanding and treatment of liver disease. Future Directions: This review comprehensively describes the distinct mitophagy signaling pathways and their interplay with various liver diseases. Given that mitophagy affects a wide array of physiological processes, a deeper understanding of how to modulate mitophagy could provide innovative avenues for precise therapy. Future studies based on pharmacologically or genetically targeting mitophagy-relevant factors will uncover the links between intact mitophagic responses and hepatic homeostasis in physiological and pathological settings. This will allow us to overcome obstacles of applying mitophagy as the therapeutic target in the clinic. Antioxid. Redox Signal. 38, 529-549.

Stromal regulation of the intestinal barrier

The intestinal barrier is a complex structure that allows the absorption of nutrients while ensuring protection against intestinal pathogens and balanced immunity. The development and maintenance of a functional intestinal barrier is a multifactorial process that is only partially understood. Here we review novel findings on the emerging role of mesenchymal cells in this process using insights gained from lineage tracing approaches, Cre-based gene deletion, and single-cell transcriptomics. The current evidence points toward a key organizer role for distinct mesenchymal lineages in intestinal development and homeostasis, regulating both epithelial and immune components of the intestinal barrier. We further discuss recent findings on functional mesenchymal heterogeneity and implications for intestinal regeneration and inflammatory intestinal pathologies.

Brusatol suppresses the tumor growth and metastasis of colorectal cancer via upregulating ARRDC4 expression through modulating PI3K/YAP1/TAZ Pathway

BACKGROUND

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers with high metastasis and lethality. Arrestin domain-containing 4 (ARRDC4) is involved in inhibiting cancer glycolytic phenotypes. Brusatol (BR), extracted from Bruceae Fructus, exerts good anti-cancer effects against a number of cancers.

PURPOSE

In the present study, we aimed to explore the efficacy of BR on inhibiting CRC metastasis and elucidate the underlying mechanisms involving the upregulation of the ARRDC4 expression.

METHODS

Cell viability, colony formation, wound healing and transwell assay were used to detect the anti-proliferative and anti-metastatic effects of BR against CRC in vitro. Microarray analysis was performed to find out differential genes in CRC cells after treatment with BR. Analysis of the CRC patients tumor samples and GEPIA database were first conducted to identify the expression of ARRDC4 on CRC. Stable overexpression and knockdown of ARRDC4 CRC cells were established by lentiviral transfection. The role of ARRDC4 in mediating the anti-metastatic effects of BR on CRC was measured using qRT-PCR, western blotting, immunohistochemical and immunofluorescence analysis. Orthotopic xenograft and pulmonary metastasis mouse models of CRC were established to determine the anti-cancer and anti-metastatic effects of ARRDC4 and BR.

RESULTS

BR markedly suppressed the cell proliferation, migration, invasion and inhibited tumor growth and tumor metastasis. Microarray analysis demonstrated that BR treatment markedly increased the gene expression of ARRDC4 in CRC cells. ARRDC4 was significantly repressed in CRC in the clinical samples and GEPIA analysis. ARRDC4 overexpression plus BR produced better inhibitory effects on CRC metastasis than BR treatment alone, while ARRDC4 knockdown could partially eliminate the inhibitory effects of BR against CRC metastasis. BR exerted anti-metastatic effects against CRC via upregulating ARRDC4 and inhibiting epithelial-mesenchymal transition (EMT) processing through modulating PI3K/Hippo pathway.

CONCLUSION

This study reported for the first time that BR is a potent ARRDC4 agonist, and is worthy of further development into a new therapeutic strategy for CRC.

The Hippo signalling pathway and its implications in human health and diseases

As an evolutionarily conserved signalling network, the Hippo pathway plays a crucial role in the regulation of numerous biological processes. Thus, substantial efforts have been made to understand the upstream signals that influence the activity of the Hippo pathway, as well as its physiological functions, such as cell proliferation and differentiation, organ growth, embryogenesis, and tissue regeneration/wound healing. However, dysregulation of the Hippo pathway can cause a variety of diseases, including cancer, eye diseases, cardiac diseases, pulmonary diseases, renal diseases, hepatic diseases, and immune dysfunction. Therefore, therapeutic strategies that target dysregulated Hippo components might be promising approaches for the treatment of a wide spectrum of diseases. Here, we review the key components and upstream signals of the Hippo pathway, as well as the critical physiological functions controlled by the Hippo pathway. Additionally, diseases associated with alterations in the Hippo pathway and potential therapies targeting Hippo components will be discussed.

From Hair to Colon: Hair Follicle-Derived MSCs Alleviate Pyroptosis in DSS-Induced Ulcerative Colitis by Releasing Exosomes in a Paracrine Manner

Ulcerative colitis (UC) has attracted intense attention due to its high recurrence rate and the difficulty of treatment. Pyroptosis has been suggested to be crucial in the development of UC. Although mesenchymal stem cells (MSCs) are broadly used for UC therapy, they have rarely been studied in the context of UC pyroptosis. Hair follicle-derived MSCs (HFMSCs) are especially understudied with regard to UC and pyroptosis. In this study, we aimed to discover the effects and potential mechanisms of HFMSCs in UC. We administered HFMSCs to dextran sulfate sodium- (DSS-) treated mice and found that the HFMSCs significantly inhibited pyroptosis to alleviate DSS-induced UC. A transwell system and GW4869, an exosome inhibitor, were used to prove the paracrine mechanism of HFMSCs. HFMSC supernatant reduced pyroptosis-related protein expression and promoted cell viability, but these effects were attenuated by GW4869, suggesting a role for HFMSC-released exosomes (Exos) in pyroptosis. Next, Exos were extracted and administered in vitro and in vivo to explore their roles in pyroptosis and UC. In addition, the biodistribution of Exos in mice was tracked using an imaging system and immunofluorescence. The results suggested that Exos not only improved DSS-induced pyroptosis and UC but also were internalized into the injured colon. Furthermore, the therapeutic efficacy of Exos was dose dependent. Among the Exo treatments, administration of 400 μg of Exos per mouse twice a week exhibited the highest efficacy. The differentially expressed miRNAs (DEmiRNAs) between MSCs and MSC-released Exos suggested that Exos might inhibit pyroptosis through tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) signalling and interferon- (IFN-) gamma pathways. Our study reveals that HFMSCs can alleviate pyroptosis in UC by releasing DEmiRNA-containing Exos in a paracrine manner. This finding may lead to new treatments for UC.

Recent insight into the role and therapeutic potential of YAP/TAZ in gastrointestinal cancers

With the rapid development of cancer treatment, gastrointestinal (GI) cancers are still the most prevalent malignancies with high morbidity and mortality worldwide. Dysregulation of the Hippo signaling pathway has been recognized to play a critical role during cancer development and adopted for monitoring disease progression and therapy response. Despite the well-documented tumor proliferation and metastasis, recent efforts in two core Hippo components, Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ), have identified as the driving forces behind cancer metabolism, stemness, tumor immunity, and therapy resistance. Understanding the molecular mechanisms by which YAP/TAZ facilitates the tumorigenesis and progression of GI cancer, and identifying novel therapeutic strategies for targeting YAP/TAZ are crucial to GI cancer treatment and prevention. In this study, we summarize the latest findings on the function and regulatory mechanisms of YAP/TAZ in GI cancers, and highlight the translational significance of targeting YAP/TAZ for cancer therapies.

Tumor microenvironmental 15-PGDH depletion promotes fibrotic tumor formation and angiogenesis in pancreatic cancer

The arachidonic acid cascade is a major inflammatory pathway that produces prostaglandin E₂ (PGE2). Although inhibition of 15‐hydroxyprostaglandin dehydrogenase (15‐PGDH) is reported to lead to PGE2 accumulation, the role of 15‐PGDH expression in the tumor microenvironment remains unclear. We utilized Panc02 murine pancreatic cancer cells for orthotopic transplantation into wild‐type and 15‐pgdh^+/− mice and found that 15‐pgdh depletion in the tumor microenvironment leads to enhanced tumorigenesis accompanied by an increase in cancer‐associated fibroblasts (CAFs) and the promotion of fibrosis. The fibrotic tumor microenvironment is widely considered to be hypovascular; however, we found that the angiogenesis level is maintained in 15‐pgdh^+/− mice, and these changes were also observed in a genetically engineered PDAC mouse model. Further confirmation revealed that fibroblast growth factor 1 (FGF1) is secreted by pancreatic cancer cells after PGE2 stimulation, consequently promoting CAF proliferation and vascular endothelial growth factor A (VEGFA) expression in the tumor microenvironment. Finally, in 15‐pgdh^+/−Acta2‐TK mice, depletion of fibroblasts inhibited angiogenesis and cancer cell viability in orthotopically transplanted tumors. These findings highlighted the role of 15‐pgdh downregulation in enhancing PGE2 accumulation in the pancreatic tumor microenvironment and in subsequently maintaining the angiogenesis level in fibrotic tumors along with CAF expansion.

Identification of hub genes and pathways in colitis-associated colon cancer by integrated bioinformatic analysis

Background

Colitis-associated colon cancer (CAC) patients have a younger age of onset, more multiple lesions and invasive tumors than sporadic colon cancer patients. Early detection of CAC using endoscopy is challenging, and the incidence of septal colon cancer remains high. Therefore, identifying biomarkers that can predict the tumorigenesis of CAC is in urgent need.

Results

A total of 275 DEGs were identified in CAC. IGF1, BMP4, SPP1, APOB, CCND1, CD44, PTGS2, CFTR, BMP2, KLF4, and TLR2 were identified as hub DEGs, which were significantly enriched in the PI3K-Akt pathway, stem cell pluripotency regulation, focal adhesion, Hippo signaling, and AMPK signaling pathways. Sankey diagram showed that the genes of both the PI3K-AKT signaling and focal adhesion pathways were upregulated (e.g., SPP1, CD44, TLR2, CCND1, and IGF1), and upregulated genes were predicted to be regulated by the crucial miRNAs: hsa-mir-16-5p, hsa-mir-1-3p, et al. Hub gene-TFs network revealed FOXC1 as a core transcription factor. In ulcerative colitis (UC) patients, KLF4, CFTR, BMP2, TLR2 showed significantly lower expression in UC-associated cancer. BMP4 and IGF1 showed higher expression in UC-Ca compared to nonneoplastic mucosa. Survival analysis showed that the differential expression of SPP1, CFRT, and KLF4 were associated with poor prognosis in colon cancer.

Conclusion

Our study provides novel insights into the mechanism underlying the development of CAC. The hub genes and signaling pathways may contribute to the prevention, diagnosis and treatment of CAC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12863-022-01065-7.

Macrophage orchestration of epithelial and stromal cell homeostasis in the intestine

The intestinal tract is a complex ecosystem where numerous cell types of epithelial, immune, neuronal, and endothelial origin coexist in an intertwined, highly organized manner. The functional equilibrium of the intestine relies heavily on the proper crosstalk and cooperation among each cell population. Furthermore, macrophages are versatile, innate immune cells that participate widely in the modulation of inflammation and tissue remodeling. Emerging evidence suggest that macrophages are central in orchestrating tissue homeostasis. Herein, we describe how macrophages interact with epithelial cells, neurons, and other types of mesenchymal cells under the context of intestinal inflammation, followed by the therapeutic implications of cellular crosstalk pertaining to the treatment of inflammatory bowel disease.

Increased Neutrophil Infiltration and Epithelial Cell Proliferation in Sinonasal Inverted Papilloma Compared to Contralateral Nasal Polyps

BACKGROUND

Sinonasal inverted papilloma (IP) is a rare and benign epithelial tumor in the sinonasal tract. Recent study suggested the potential role of chronic inflammation in the pathogenesis of IP. This study aims to compare the inflammatory pattern, the capacity of epithelial cell proliferation and EGFR mutation status of unilateral IP with contralateral polyp tissue.

METHODS

Sixteen patients with unilateral IP and contralateral nasal polyps (NP) were identified through a retrospective chart review. The neutrophil and eosinophil infiltration in IP and NP were assessed by immunostaining for neutrophil elastase and major basic protein (MBP). Immunohistochemistry was also used to assess the expression of FoxM1, Ki67 and cyclin D1 in IP tissue and contralateral NP. Sanger sequencing was used to evaluate the EGFR mutations.

RESULTS

The neutrophil count in IP was significantly higher than contralateral NP and 68.8% patients presented with neutrophilic inflammation, whereas only 37.5% contralateral NP tissue showed neutrophilic inflammation. The percentage of positive FoxM1-staining cells was significantly increased in IP, and positively correlated with the percentage of cells with positive staining for cyclin D1 and ki67 as well as neutrophil counts. EGFR exon 20 insertions were detected in 14 (87.5%) IP samples and no EGFR mutations were found in contralateral NP sample.

CONCLUSION

Our study demonstrated distinct inflammatory pattern between IP and contralateral NP and implied the oncogenic role of neutrophils in the pathogenesis of IP. EGFR mutations may be the early event to initiate IP development by enhancing epithelial cell proliferation.

Adaptive differentiation promotes intestinal villus recovery

Loss of differentiated cells to tissue damage is a hallmark of many diseases. In slow-turnover tissues, long-lived differentiated cells can re-enter the cell cycle or transdifferentiate to another cell type to promote repair. Here, we show that in a high-turnover tissue, severe damage to the differentiated compartment induces progenitors to transiently acquire a unique transcriptional and morphological postmitotic state. We highlight this in an acute villus injury model in the mouse intestine, where we identified a population of progenitor-derived cells that covered injured villi. These atrophy-induced villus epithelial cells (aVECs) were enriched for fetal markers but were differentiated and lineage committed. We further established a role for aVECs in maintaining barrier integrity through the activation of yes-associated protein (YAP). Notably, loss of YAP activity led to impaired villus regeneration. Thus, we define a key repair mechanism involving the activation of a fetal-like program during injury-induced differentiation, a process we term "adaptive differentiation."

YAP/TAZ: Key Players for Rheumatoid Arthritis Severity by Driving Fibroblast Like Synoviocytes Phenotype and Fibro-Inflammatory Response

Objective

The role of YAP/TAZ, two transcriptional co-activators involved in several cancers, was investigated in rheumatoid arthritis (RA).

Methods

Fibroblast like synoviocytes (FLS) from patients with RA or osteoarthritis were cultured in 2D or into 3D synovial organoids. Arthritis rat model (n=28) and colitis mouse model (n=21) were used. YAP/TAZ transcriptional activity was inhibited by verteporfin (VP). Multiple techniques were used to assess gene and/or protein expression and/or localization, cell phenotype (invasion, proliferation, apoptosis), bone erosion, and synovial stiffness.

Results

YAP/TAZ were transcriptionally active in arthritis (19-fold increase for CTGF expression, a YAP target gene, in RA vs. OA organoids; p<0.05). Stiff support of culture or pro-inflammatory cytokines further enhanced YAP/TAZ transcriptional activity in RA FLS. Inhibiting YAP/TAZ transcriptional activity with VP restored a common phenotype in RA FLS with a decrease in apoptosis resistance, proliferation, invasion, and inflammatory response. Consequently, VP blunted hyperplasic lining layer formation in RA synovial organoids. In vivo, VP treatment strongly reduced arthritis severity (mean arthritic index at 3.1 in arthritic group vs. 2.0 in VP treated group; p<0.01) by restoring synovial homeostasis and decreasing systemic inflammation. YAP/TAZ transcriptional activity also enhanced synovial membrane stiffening in vivo, thus creating a vicious loop with the maintenance of YAP/TAZ activation over time in FLS. YAP/TAZ inhibition was also effective in another inflammatory model of mouse colitis.

Conclusion

Our work reveals that YAP/TAZ were critical factors during arthritis. Thus, their transcriptional inhibition could be relevant to treat inflammatory related diseases.

Injury-Induced Cellular Plasticity Drives Intestinal Regeneration

The epithelial lining of the intestine, particularly the stem cell compartment, is affected by harsh conditions in the luminal environment and also is susceptible to genotoxic agents such as radiation and chemotherapy. Therefore, the ability for intestinal epithelial cells to revert to a stem cell state is an important physiological damage response to regenerate the intestinal epithelium at sites of mucosal injury. Many signaling networks involved in maintaining the stem cell niche are activated as part of the damage response to promote cellular plasticity and regeneration. The relative contribution of each cell type and signaling pathway is a critical area of ongoing research, likely dependent on the nature of injury as well as the regional specification within the intestine. Here, we review the current understanding of the multicellular cooperation to restore the intestinal epithelium after damage.

Chemoprevention by aspirin against inflammation-related colorectal cancer in mice

Inflammation is a primary risk factor for cancer. Epidemiological studies previously demonstrated that aspirin decreased the incidence of cancer and specifically reduced the risk of colorectal cancer. However, the number of animal studies that have confirmed the efficacy of aspirin remains limited. Therefore, the purpose of the present study was to investigate the mechanisms by which aspirin prevents colorectal cancer in mice. ICR mice were treated with azoxymethane and the ulcerative colitis inducer, dextran sodium sulfate, to induce colorectal tumors. Aspirin was orally administered three times per week for 12 weeks. Aspirin significantly reduced the number and size of colorectal tumors. Aspirin also significantly decreased tumor necrosis factor alpha and reactive oxygen species (ROS) levels in the plasma. Immunohistochemical analyses and western blots showed that cyclooxygenase 2 (COX2), inducible nitric oxide synthase (iNOS), and the active form of Yes-associated protein 1 (YAP1), and cytosolic high mobility group box 1 (HMGB1) were strongly expressed at colorectal tumor sites and clearly suppressed by aspirin. An indicator of inflammation-related DNA damage, 8-nitroguanine, also accumulated in the colorectal tissues and was suppressed by aspirin. The present results suggest that the ingestion of aspirin suppressed carcinogenesis caused by inflammation through decreases in COX2 and ROS levels, resulting in reductions in DNA damage and oncogenic YAP1.

Renal subcapsular delivery of PGE2 promotes kidney repair by activating endogenous Sox9+ stem cells

Prostaglandin E₂ (PGE₂) has recently been recognized to play a role in immune regulation and tissue regeneration. However, the short half-life of PGE₂ limits its clinical application. Improving the delivery of PGE₂ specifically to the target organ with a prolonged release method is highly desirable. Taking advantage of the adequate space and proximity of the renal parenchyma, renal subcapsular delivery allows minimally invasive and effective delivery to the entire kidney. Here, we report that by covalently cross-linking it to a collagen matrix, PGE₂ exhibits an adequate long-term presence in the kidney with extensive intraparenchymal penetration through renal subcapsular delivery and significantly improves kidney function. Sox9 cell lineage tracing with intravital microscopy revealed that PGE₂ could activate the endogenous renal progenitor Sox9⁺ cells through the Yap signaling pathway. Our results highlight the prospects of utilizing renal subcapsular-based drug delivery and facilitate new applications of PGE₂-releasing matrices for regenerative therapy.

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PGE₂ exhibits an adequate long-term release by being covalently cross-linked to collagen

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The renal subcapsular space serves as a reservoir for the delivery of PGE₂

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Sox9⁺ renal progenitor cells can be lineage traced intravitally by microscopy

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PGE₂ activates the endogenous renal progenitor Sox9⁺ cells through the YAP pathway

Role of the extracellular matrix and YAP/TAZ in cell reprogramming

Stem cells are crucial in the fields of regenerative medicine and cell therapy. Mechanical signals from the cellular microenvironment play an important role in inducing the reprogramming of somatic cells into stem cells in vitro, but the mechanisms of this process have yet to be fully explored. Mechanical signals may activate a physical pathway involving the focal adhesions-cytoskeleton-LINC complex axis, and a chemical pathway involving YAP/TAZ. ENH protein likely plays an important role in connecting and regulating these two pathways. Such mechanisms illustrate one way in which mechanical signals from the cellular microenvironment can induce reprogramming of somatic cells to stem cells, and lays the foundation for a new strategy for inducing and regulating such reprogramming in vitro by means of physical processes related to local mechanical forces.

Treatment of acromegaly by rosiglitazone via upregulating 15-PGDH in both pituitary adenoma and liver

Rosiglitazone, a synthetic peroxisome proliferator-activated receptor γ (PPARγ) ligand, has been reported to reduce growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in 10 patients with acromegaly. However, the mechanisms remain unknown. Here, we reveal that PPARγ directly enhances 15-hydroxyprostaglandin dehydrogenase (15-PGDH) expression, whose expression is decreased and negatively correlates with tumor size in acromegaly. Rosiglitazone decreases GH production and promotes apoptosis and autophagy in GH3 and primary somatotroph adenoma cells and suppresses hepatic GH receptor (GHR) expression and IGF-1 secretion in HepG2 cells. Activating the PGE2/cAMP/PKA pathway directly increases GHR expression. Rosiglitazone suppresses tumor growth and decreases GH and IGF-1 levels in mice inoculated subcutaneously with GH3 cells. The above effects are all dependent on 15-PGDH expression. Rosiglitazone as monotherapy effectively decreases GH and IGF-1 levels in all nineteen patients with active acromegaly. Evidence suggests that rosiglitazone may be an alternative pharmacological approach for acromegaly by targeting both pituitary adenomas and liver.

Role of prostaglandin E2 in tissue repair and regeneration

Tissue regeneration following injury from disease or medical treatment still represents a challenge in regeneration medicine. Prostaglandin E2 (PGE2), which involves diverse physiological processes via E-type prostanoid (EP) receptor family, favors the regeneration of various organ systems following injury for its capabilities such as activation of endogenous stem cells, immune regulation, and angiogenesis. Understanding how PGE2 modulates tissue regeneration and then exploring how to elevate the regenerative efficiency of PGE2 will provide key insights into the tissue repair and regeneration processes by PGE2. In this review, we summarized the application of PGE2 to guide the regeneration of different tissues, including skin, heart, liver, kidney, intestine, bone, skeletal muscle, and hematopoietic stem cell regeneration. Moreover, we introduced PGE2-based therapeutic strategies to accelerate the recovery of impaired tissue or organs, including 15-hydroxyprostaglandin dehydrogenase (15-PGDH) inhibitors boosting endogenous PGE2 levels and biomaterial scaffolds to control PGE2 release.

Biomaterials for intestinal organoid technology and personalized disease modeling

Recent advances in intestinal organoid technologies have paved the way for in vitro recapitulation of the homeostatic renewal of adult tissues, tissue or organ morphogenesis during development, and pathogenesis of many disorders. In vitro modelling of individual patient diseases using organoid systems have been considered key in establishing rational design of personalized treatment strategies and in improving therapeutic outcomes. In addition, the transplantation of organoids into diseased tissues represents a novel approach to treat currently incurable diseases. Emerging evidence from intensive studies suggests that organoid systems' development and functional maturation depends on the presence of an extracellular matrix with suitable biophysical properties, where advanced synthetic hydrogels open new avenues for theoretical control of organoid phenotypes and potential applications of organoids in therapeutic purposes. In this review, we discuss the status, applications, challenges and perspectives of intestinal organoid systems emphasising on hydrogels and their properties suitable for intestinal organoid culture. We provide an overview of hydrogels used for intestinal organoid culture and key factors regulating their biological activity. The comparison of different hydrogels would be a theoretical basis for establishing design principles of synthetic niches directing intestinal cell fates and functions. STATEMENT OF SIGNIFICANCE: Intestinal organoid is an in vitro recapitulation of the gut, which self-organizes from intestinal stem cells and maintains many features of the native tissue. Since the development of this technology, intestinal organoid systems have made significant contribution to rapid progress in intestinal biology. Prevailing methodology for organoid culture, however, depends on animal-derived matrices and suffers from variability and potential risk for contamination of pathogens, limiting their therapeutic application. Synthetic scaffold matrices, hydrogels, might provide solutions to these issues and deepen our understanding on how intestinal cells sense and respond to key biophysical properties of the surrounding matrices. This review provides an overview of developing intestinal models and biomaterials, thereby leading to better understanding of current intestinal organoid systems for both biologists and materials scientists.

Delta-5-desaturase: A novel therapeutic target for cancer management

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D5D is an independent prognostic factor in cancer.

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D5D aggravates cancer progression via mediating AA/PGE₂ production from DGLA.

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AA/PGE₂ promotes cancer progression via regulating the tumor microenvironment.

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Inhibition of D5D redirects COX-2 catalyzed DGLA peroxidation, producing 8-HOA.

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8-HOA suppress cancer by regulating proliferation, apoptosis, and metastasis.

Delta-5 desaturase (D5D) is a rate-limiting enzyme that introduces double-bonds to the delta-5 position of the n-3 and n-6 polyunsaturated fatty acid chain. Since fatty acid metabolism is a vital factor in cancer development, several recent studies have revealed that D5D activity and expression could be an independent prognostic factor in cancers. However, the mechanistic basis of D5D in cancer progression is still controversial. The classical concept believes that D5D could aggravate cancer progression via mediating arachidonic acid (AA)/prostaglandin E₂ production from dihomo-γ-linolenic acid (DGLA), resulting in activation of EP receptors, inflammatory pathways, and immunosuppression. On the contrary, D5D may prevent cancer progression through activating ferroptosis, which is iron-dependent cell death. Suppression of D5D by RNA interference and small-molecule inhibitor has been identified as a promising anti-cancer strategy. Inhibition of D5D could shift DGLA peroxidation pattern from generating AA to a distinct anti-cancer free radical byproduct, 8-hydroxyoctanoic acid, resulting in activation of apoptosis pathway and simultaneously suppression of cancer cell survival, proliferation, migration, and invasion. Hence, understanding the molecular mechanisms of D5D on cancer may therefore facilitate the development of novel therapeutical applications. Given that D5D may serve as a promising target in cancer, in this review, we provide an updated summary of current knowledge on the role of D5D in cancer development and potentially useful therapeutic strategies.

Emerging roles for the YAP/TAZ transcriptional regulators in brain tumour pathology and targeting options

The transcriptional co-activators Yes-associated protein 1/transcriptional co-activator with PDZ-binding motif (YAP/TAZ) have emerged as significant regulators of a wide variety of cellular and organ functions with impact in early embryonic development, especially during the expansion of the neural progenitor cell pool. YAP/TAZ signalling regulates organ size development, tissue homeostasis, wound healing and angiogenesis by participating in a complex network of various pathways. However, recent evidence suggests an association of these physiologic regulatory effects of YAP/TAZ with pro-oncogenic activities. Herein, we discuss the physiological functions of YAP/TAZ as well as the extensive network of signalling pathways that control their expression and activity, leading to brain tumour development and progression. Furthermore, we describe current targeting approaches and drug options including direct YAP/TAZ and YAP-TEA domain transcription factor (TEAD) interaction inhibitors, G-protein coupled receptors (GPCR) signalling modulators and kinase inhibitors, which may be used to successfully attack YAP/TAZ-dependent tumours.

A resident stromal cell population actively restrains innate immune response in the propagation phase of colitis pathogenesis in mice

Inflammatory bowel disease (IBD) affects 0.3% of the global population, yet the etiology remains poorly understood. Anti-inflammation therapy has shown great success, but only 60% of patients with IBD benefit from it, indicating that new targets are needed. Here, we report the discovery of an intrinsic counter regulatory mechanism in colitis pathogenesis that may be targeted for IBD treatment. In response to microbial invasion, resident Vimentin⁺ stromal cells, connective tissue cells genetically marked by Twist2, are activated during the propagation phase of the disease, but not during initiation and resolution phases, and become a primary source of prostaglandin E₂ (PGE₂). PGE₂ induction requires a nuclear factor κB-independent, TLR4-p38MAPK-Cox2 pathway activation. Ablation of each of the pathway genes, but not Rela or Tgfb1, in Twist2 cells enhanced M1 macrophage polarization and granulocyte/T helper 1 (T_H1)/T_H17 infiltration and aggravated colitis development. PGE₂ administration ameliorated colitis in mouse models with defective PGE₂ production but not in animals with normal PGE₂ induction. Analysis of clinical samples and public domain data revealed increased expression of Cox2, the rate-limiting enzyme of PGE₂ biosynthesis, in inflamed tissues, and especially in colon Vimentin⁺Twist2⁺ stromal cells, in about 60% of patients with active Crohn's disease or ulcerative colitis. Moreover, Cox2 protein expression was negatively correlated with disease severity, suggesting an involvement of stromal cells in IBD pathogenesis. Thus, the study uncovers an active immune pathway in colitic inflammation that may be targeted to treat patients with IBD with defects in PGE₂ production.

CD147 receptor is essential for TFF3-mediated signaling regulating colorectal cancer progression

Major gaps in understanding the molecular mechanisms of colorectal cancer (CRC) progression and intestinal mucosal repair have hampered therapeutic development for gastrointestinal disorders. Trefoil factor 3 (TFF3) has been reported to be involved in CRC progression and intestinal mucosal repair; however, how TFF3 drives tumors to become more aggressive or metastatic and how TFF3 promotes intestinal mucosal repair are still poorly understood. Here, we found that the upregulated TFF3 in CRC predicted a worse overall survival rate. TFF3 deficiency impaired mucosal restitution and adenocarcinogenesis. CD147, a membrane protein, was identified as a binding partner for TFF3. Via binding to CD147, TFF3 enhanced CD147-CD44s interaction, resulting in signal transducer and activator of transcription 3 (STAT3) activation and prostaglandin G/H synthase 2 (PTGS2) expression, which were indispensable for TFF3-induced migration, proliferation, and invasion. PTGS2-derived PGE2 bound to prostaglandin E2 receptor EP4 subtype (PTGER4) and contributed to TFF3-stimulated CRC progression. Solution NMR studies of the TFF3-CD147 interaction revealed the key residues critical for TFF3 binding and the induction of PTGS2 expression. The ability of TFF3 to enhance mucosal restitution was weakened by a PTGS2 inhibitor. Blockade of TFF3-CD147 signaling using competitive inhibitory antibodies or a PTGS2 inhibitor reduced CRC lung metastasis in mice. Our findings bring strong evidence that CD147 is a novel receptor for TFF3 and PTGS2 signaling is critical for TFF3-induced mucosal restitution and CRC progression, which widens and deepens the understanding of the molecular function of trefoil factors.

Taking a Step Back: Insights into the Mechanisms Regulating Gut Epithelial Dedifferentiation

Despite the environmental constraints imposed upon the intestinal epithelium, this tissue must perform essential functions such as nutrient absorption and hormonal regulation, while also acting as a critical barrier to the outside world. These functions depend on a variety of specialized cell types that are constantly renewed by a rapidly proliferating population of intestinal stem cells (ISCs) residing at the base of the crypts of Lieberkühn. The niche components and signals regulating crypt morphogenesis and maintenance of homeostatic ISCs have been intensely studied over the last decades. Increasingly, however, researchers are turning their attention to unraveling the mechanisms driving gut epithelial regeneration due to physical damage or infection. It is now well established that injury to the gut barrier triggers major cell fate changes, demonstrating the highly plastic nature of the gut epithelium. In particular, lineage tracing and transcriptional profiling experiments have uncovered several injury-induced stem-cell populations and molecular markers of the regenerative state. Despite the progress achieved in recent years, several questions remain unresolved, particularly regarding the mechanisms driving dedifferentiation of the gut epithelium. In this review, we summarize the latest studies, primarily from murine models, that define the regenerative processes governing the gut epithelium and discuss areas that will require more in-depth investigation.

Reprogramming cellular identity during intestinal regeneration

The intestine is a vital organ mediating absorption of nutrients and water. Following tissue damage, the intestine mounts a remarkable regenerative response by reprogramming cellular identity to facilitate reinstatement of homeostasis. Here we review recent advances within intestinal regenerative biology and the emerging concept of fetal-like reprogramming, in which the adult intestinal epithelium transiently enters a repair-associated state reminiscent of ontologically pre-existing stages. We focus on molecular mechanisms governing reprogramming of cellular identity via epithelial-mesenchymal crosstalk, and how novel approaches in organoid technologies enable identification and characterisation of cell-autonomous repair responses within epithelial cells. Transitioning from the single-cell level to tissue scale, we discuss clonal selection following regeneration and associated pathological repurcussions such as cancer and chronic inflammatory diseases.

Anterior Gradient Protein 2 Promotes Mucosal Repair in Pediatric Ulcerative Colitis

Mucosal healing comprises a key goal of ulcerative colitis (UC) treatment. Anterior gradient protein 2 (AGR2) plays an important role in maintaining intestinal homeostasis in UC. However, the role of AGR2 in the repair of mucosal injury is not yet clear. This study is aimed at investigating the expression of AGR2 in the intestinal tissues of children with UC and its role in repairing mucosal injury. Forty UC patients who were hospitalized in the Pediatric Gastroenterology Ward of Shengjing Hospital affiliated with China Medical University between July 1, 2013, and May 31, 2020, and 20 children who had normal colonoscopy results during the same period (control group) made up the study sample. The disease activity of UC was evaluated based on the pediatric ulcerative colitis activity index, and the ulcerative colitis endoscopic index was evaluated according to the Rachmilewitz score. Immunohistochemical staining was employed to examine the differences in AGR2 expression in the intestinal mucosa between groups. The protective effect of AGR2 in a model of tumor necrosis factor-alpha- (TNF-α-) induced intestinal mucosal barrier injury and the underlying molecular mechanism were explored through in vitro experiments. The results showed that compared with the normal control group, UC patients in the remission or active period had significantly higher expression of AGR2 in the intestine. AGR2 expression was positively correlated with Ki67, an intestinal epithelial cell proliferation marker, but negatively correlated with the degree of endoscopic mucosal injury. In an in vitro model, AGR2 overexpression promoted cell proliferation and migration and inhibited TNF-α-induced intestinal epithelial barrier damage by activating yes-associated protein (YAP). Collectively, our study suggests that AGR2 might serve as a valuable biomarker to help assess the condition and mucosal healing status of UC patients. In vitro, AGR2 promoted the repair of intestinal mucosal barrier injury by activating YAP.

M2 Macrophage-Derived Exosomal miR-590-3p Attenuates DSS-Induced Mucosal Damage and Promotes Epithelial Repair via the LATS1/YAP/ β-Catenin Signalling Axis

BACKGROUND AND AIMS

M2 phenotype macrophages are involved in the resolution of inflammation and intestinal repair. Exosomes are emerging as important mediators of intercellular communication in the mucosal microenvironment.

METHODS

M2 macrophages were transfected with or without miR-590-3p. Exosomes derived from M2 macrophages were isolated and identified. Proliferation and wound healing were tested in vitro and compared between groups. The mechanism involving LATS1, and activation of YAP and β-catenin signalling was investigated by using plasmid transfection, western blotting, immunofluorescence and luciferase reporter assays. The effect of exosomes in vivo was detected in dextran saline sulphate [DSS]-induced murine colitis.

RESULTS

First, we demonstrated that M2 macrophages promoted colonic epithelial cell proliferation in an exosome-dependent manner. Epithelial YAP mediated the effect of M2 macrophage-derived exosomes [M2-exos] in epithelial proliferation. Moreover, miR-590-3p, which was significantly enriched in M2-exos, could be transferred from macrophages into epithelial cells, resulting in the enhanced proliferation and wound healing of epithelial cells. Mechanistically, miR-590-3p suppressed the expression of LATS1 by binding to its coding sequence and subsequently activated the YAP/β-catenin-modulated transcription process to improve epithelial cell wound-healing ability. miR-590-3p also inhibited the induction of pro-inflammatory cytokines, including tumour necrosis factor-α, interleukin-1β [IL-1β] and IL-6. More importantly, repression of miR-590-3p in M2-exos resulted in more severe mucosal damage and impaired colon repair of mice compared with those in M2-exo-treated mice after DSS-induced colitis.

CONCLUSION

M2 macrophage-derived exosomal miR-590-3p reduces inflammatory signals and promotes epithelial regeneration by targeting LATS1 and subsequently activating YAP/β-catenin-regulated transcription, which could offer a new opportunity for clinical therapy for ulcerative colitis.