Wnt, RSPO and Hippo Signalling in the Intestine and Intestinal Stem Cells

The intestinal stem cell as a target: A review

Human intestinal epithelium handles several events that may affect health. It is composed of villi and crypts, which contain different types of cells. Each cell type plays an essential role in intestinal functions, including absorption, defense, self-renewal, and regeneration. Intestinal stem cells (ISCs), located at the base of intestinal crypts, play an important role in intestinal homeostasis and renewal. Any disruption in intestinal homeostasis, in which ISCs alter their function, may result in tumor growth. As Wnt and Notch signaling pathways are essential for ISCs homeostasis and for maintaining self-renewal, any defects in these pathways could increase the risk of developing colorectal cancer (CRC). Lgr5+ cells have been identified as intestinal stem cells expressing a leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5), which is involved in the regulation of Wnt signaling. Several studies have reported upregulated expression of LGR5 in CRC. Hence, in this review, we discuss the relationship between LGR5, Wnt signaling, and Notch signaling and the development of CRC, as well as recent therapeutic strategies targeting LGR5, cancer stem cells (CSCs), and the aforementioned signaling pathways.

Overexpression of transcription factor TBX5 inhibits the activation of YAP1-TEAD1 pathway to promote ferroptosis in lung cancer cells

BACKGROUND

Non-small cell lung cancer (NSCLC) accounts for more than 80 % of lung cancer (LC) cases, making it the primary cause of cancer-related mortality worldwide. T-box transcription factor 5 (TBX5) is an important regulator of embryonic and organ development and plays a key role in cancer development. Here, our objective was to investigate the involvement of TBX5 in ferroptosis within LC cells and the underlying mechanisms.

METHODS

First, TBX5 expression was examined in human LC cells. Next, overexpression of TBX5 and Yes1-associated transcriptional regulator (YAP1) and knockdown of TEA domain 1 (TEAD1) were performed in A549 and NCI-H1703 cells. The proliferation ability of A549 and NCI-H1703 cells, GSH, MDA, ROS, and Fe2+ levels were measured. Co-immunoprecipitation (Co-IP) was performed to verify whether TBX5 protein could bind YAP1. Then TBX5, YAP1, TEAD1, GPX4, p53, FTH1, SLC7A11 and PTGS2 protein levels were assessed. Finally, we verified the effect of TBX5 on ferroptosis in LC cells in vivo.

RESULTS

TBX5 expression was down-regulated in LC cells, especially in A549 and NCI-H1703 cells. Overexpression of TBX5 significantly decreased proliferation ability of A549 and NCI-H1703 cells, downregulated GPX4 and GSH levels, and upregulated MDA, ROS, and Fe2+ levels. Co-IP verified that TBX5 protein could bind YAP1. Moreover, oe-YAP1 promoted proliferation ability of A549 and NCI-H1703 cells transfected with Lv-TBX5, upregulated GPX4 and GSH levels and downregulated MDA, ROS, and Fe2+ levels. Additionally, oe-YAP1 promoted FTH1 and SLC7A11 levels and inhibited p53 and PTGS2 levels in A549 and NCI-H1703 cells transfected with Lv-TBX5. However, transfection with si-TEAD1 further reversed these effects. In vivo experiments further validated that TBX5 promoted ferroptosis in LC cells.

CONCLUSIONS

TBX5 inhibited the activation of YAP1-TEAD1 pathway to promote ferroptosis in LC cells.

Context-dependent T-BOX transcription factor family: from biology to targeted therapy

T-BOX factors belong to an evolutionarily conserved family of transcription factors. T-BOX factors not only play key roles in growth and development but are also involved in immunity, cancer initiation, and progression. Moreover, the same T-BOX molecule exhibits different or even opposite effects in various developmental processes and tumor microenvironments. Understanding the multiple roles of context-dependent T-BOX factors in malignancies is vital for uncovering the potential of T-BOX-targeted cancer therapy. We summarize the physiological roles of T-BOX factors in different developmental processes and their pathological roles observed when their expression is dysregulated. We also discuss their regulatory roles in tumor immune microenvironment (TIME) and the newly arising questions that remain unresolved. This review will help in systematically and comprehensively understanding the vital role of the T-BOX transcription factor family in tumor physiology, pathology, and immunity. The intention is to provide valuable information to support the development of T-BOX-targeted therapy.

Genome-wide comparative analysis reveals selection signatures for reproduction traits in prolific Suffolk sheep

The identification of genome-wide selection signatures can reveal the potential genetic mechanisms involved in the generation of new breeds through natural or artificial selection. In this study, we screened the genome-wide selection signatures of prolific Suffolk sheep, a new strain of multiparous mutton sheep, to identify candidate genes for reproduction traits and unravel the germplasm characteristics and population genetic evolution of this new strain of Suffolk sheep. Whole-genome resequencing was performed at an effective sequencing depth of 20× for genomic diversity and population structure analysis. Additionally, selection signatures were investigated in prolific Suffolk sheep, Suffolk sheep, and Hu sheep using fixation index (F ST) and heterozygosity H) analysis. A total of 5,236.338 Gb of high-quality genomic data and 28,767,952 SNPs were obtained for prolific Suffolk sheep. Moreover, 99 selection signals spanning candidate genes were identified. Twenty-three genes were significantly associated with KEGG pathway and Gene Ontology terms related to reproduction, growth, immunity, and metabolism. Through selective signal analysis, genes such as ARHGEF4, CATIP, and CCDC115 were found to be significantly correlated with reproductive traits in prolific Suffolk sheep and were highly associated with the mTOR signaling pathway, the melanogenic pathway, and the Hippo signaling pathways, among others. These results contribute to the understanding of the evolution of artificial selection in prolific Suffolk sheep and provide candidate reproduction-related genes that may be beneficial for the establishment of new sheep breeds.

Multiomics data identifies RSPO2 as a prognostic biomarker in human tumors associated with pan-cancer

RSPO2 protein may provide valuable insights into the mechanism underlying various types of tumorigenesis. The role of RSPO2 in pan-cancer has not been reported so far. Therefore, this study aimed to provide a comprehensive analysis of RSPO2 from a pan-cancer perspective employing multiomics data. The expression profile and function of RSPO2 across different tumors were investigated using various web-based tools UALCAN, GEPIA, TIMER, Human Protein Atlas, cBioPortal, TISIDB, STRING, and Metascape to interpret the expression profile, promoter methylation status, genomic alterations, survival analysis, protein-protein interaction, correlation with immune cell subtypes, tumor immune microenvironment and enrichment analysis. Comprehensive pan-cancer analysis indicated that RSPO2 was significantly downregulated in eleven and upregulated in five tumor types compared to normal tissues, validation results further suggest RSPO2 was downregulated in most of the tumors. The protein level expression of RSPO2 was mostly low in malignant tissues. We found that RSPO2 was significantly related to individual pathological stages in BLCA, COAD, LUAD and LUSC. Prognostic analysis indicates that the high RSPO2 expression was significantly correlated with the poor prognosis in BRCA, KICH, KIRP, READ, and UCES. Furthermore, RSPO2 is frequently amplified, exhibits hypermethylated promoter in most cancers, and is associated with immune subtypes, molecular subtypes and immune cell infiltration. Finally, enrichment analysis showed that RSPO2 is involved in the regulation of the canonical Wnt pathway and neuronal development. The overall comprehensive pan-cancer analysis affirms that RSPO2 could be a promising diagnostic and prognostic biomarker and latent therapy target in the future.

27-Hydroxycholesterol activates the GSK-3β/β-catenin signaling pathway resulting in intestinal fibrosis by inducing oxidative stress: effect of dietary interventions

OBJECTIVE

Intestinal fibrosis, a common and serious complication of inflammatory bowel disease (IBD), results from chronic inflammation. A high-cholesterol diet may be a risk factor for IBD and 27-hydroxylcholesterol (27HC) is the main human cholesterol metabolite. This study investigated whether 27HC can induce intestinal fibrosis.

METHODS

The effects of cholesterol and 27HC on intestinal fibrosis were assessed in zebrafish and human intestinal epithelial Caco-2 cells.

RESULTS

Cholesterol and 27HC induced intestinal inflammation and collagen deposition, inhibited E-cadherin (E-ca) expression in the intestinal epithelium, and promoted nuclear translocation of β-catenin in zebrafish. Cholesterol and 27HC up-regulated expression of COL-1, α-SMA, CTGF, TIMP1, N-cadherin, vimentin, glycogen synthesis kinase-3β (GSK-3β) and β-catenin, but inhibited E-ca, in Caco-2 cells. The expression of these proteins was inhibited by CYP27A1 knockdown and β-catenin knockdown. 27HC-induced nuclear translocation of β-catenin occurs in Caco-2 cells. p38, ERK, and AKT activate β-catenin and thereby participate in 27HC-induced epithelia-mesenchymal transition (EMT) and fibrosis. 27HC-increased oxidative stress and the fibrosis and EMT markers, the nuclear translocation of β-catenin, and the up-regulation of p-cell kinase proteins promoted by 27HC were inhibited by N-acetyl-L-cysteine (NAC). Folic acid (FA), resveratrol (RES), and NAC all ameliorated the 27HC-induced effects in Caco-2 cells and zebrafish.

CONCLUSION

A high-cholesterol diet caused intestinal fibrosis in zebrafish, mediated by a major cholesterol metabolite, 27HC. 27HC increased oxidative stress and activated p38, ERK, AKT, and β-catenin, leading to EMT of epithelial cells and intestinal fibrosis. FA and RES both ameliorated intestinal fibrosis by restraining 27HC-induced β-catenin activation.

Potential Application of Intestinal Organoids in Intestinal Diseases

To accurately reveal the scenario and mecahnism of gastrointestinal diseases, the establishment of in vitro models of intestinal diseases and drug screening platforms have become the focus of attention. Over the past few decades, animal models and immortalized cell lines have provided valuable but limited insights into gastrointestinal research. In recent years, the development of intestinal organoid culture system has revolutionized in vitro studies of intestinal diseases. Intestinal organoids are derived from self-renewal and self-organization intestinal stem cells (ISCs), which can replicate the genetic characteristics, functions, and structures of the original tissues. Consequently, they provide new stragety for studying various intestinal diseases in vitro. In the review, we will discuss the culture techniques of intestinal organoids and describe the use of intestinal organoids as research tools for intestinal diseases. The role of intestinal epithelial cells (IECs) played in the pathogenesis of inflammatory bowel diseases (IBD) and the treatment of intestinal epithelial dysfunction will be highlighted. Besides, we review the current knowledge on using intestinal organoids as models to study the pathogenesis of IBD caused by epithelial dysfunction and to develop new therapeutic approaches. Finally, we shed light on the current challenges of using intestinal organoids as in vitro models.

Mettl14-mediated m6 A modification regulates the abnormal differentiation of small intestinal epithelial stem cells in diabetic state

Diabetes mellitus (DM) and its related complications are a global epidemic characterized by high morbidity and mortality. However, little is known about diabetic enteropathy (DE) and its the potential underlying mechanism. Intestinal epithelial stem cells (IESCs) were harvested from experimental mice, and the levels of dominant N6-methyladenosine (m6 A)-related enzyme were detected by RT-PCR, Western blotting, immunohistochemistry. The role of Mettl14 in the abnormal differentiation of intestinal epithelial cells (IECs) during DM was confirmed by knockdown experiments. RT-PCR, MeRIP, and bioinformatics analysis were carried out to confirm the downstream target of Mettl14. Through bioinformatics analysis, RT-PCR, and Western blotting, we further analyzed the differentiation-related gene in the IECs from mice with DM. In this study, the levels of Mettl14 and m6 A were higher in db/db mice than that in control mice. And abnormal differentiation of IECs in DM was associated with Mettl14 overexpression. Additionally, Mettl14 is a major determinant of IESCs identity and organoid-forming upon DM state. Mechanistically, we revealed that the candidate binding target of Mettl14 was Fzd2 mRNA and affected Fzd2 stability. Moreover, Mettl14 downregulation was observed to attenuate the abnormal differentiation of IECs through modulating Fzd2 m6A modification in DM state. Together, our results provide definitive evidence for the essential role of Mettl14 in differentiation of IESCs in DM state.

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.

Enhanced binding of β-catenin and β-TrCP mediates LMPt's anti-CSCs activity in colorectal cancer

Cancer stem cells (CSCs), a subpopulation of tumor cells with the features of self-renewal, tumor initiation, and insensitivity to common physical and chemical agents, are the key to cancer relapses, metastasis, and resistance. Accessible CSCs inhibitory strategies are primarily based on small molecule drugs, yet toxicity limits their application. Here, we report a liposome loaded with low toxicity and high effectiveness of miriplatin, lipo-miriplatin (LMPt) with high miriplatin loading, and robust stability, exhibiting a superior inhibitory effect on CSCs and non-CSCs. LMPt predominantly inhibits the survival of oxaliplatin-resistant (OXA-resistant) cells composed of CSCs. Furthermore, LMPt directly blocks stemness features of self-renewal, tumor initiation, unlimited proliferation, metastasis, and insensitivity. In mechanistic exploration, RNA sequencing (RNA-seq) revealed that LMPt downregulates the levels of pro-stemness proteins and that the β-catenin-mediated stemness pathway is enriched. Further research shows that either in adherent cells or 3D-spheres, the β-catenin-OCT4/NANOG axis, the vital pathway to maintain stemness, is depressed by LMPt. The consecutive activation of the β-catenin pathway induced by mutant β-catenin (S33Y) and OCT4/NANOG overexpression restores LMPt's anti-CSCs effect, elucidating the key role of the β-catenin-OCT4/NANOG axis. Further studies revealed that the strengthened binding of β-catenin and β-TrCP initiates ubiquitination and degradation of β-catenin induced by LMPt. In addition,the Apc^Min/+transgenicmouse model, in which colon tumors are spontaneously formed, demonstrates LMPt's potent anti-non-CSCs activity in vivo.

Targeting Wnt/β-Catenin Pathway by Flavonoids: Implication for Cancer Therapeutics

The Wnt pathway has been recognized for its crucial role in human development and homeostasis, but its dysregulation has also been linked to several disorders, including cancer. Wnt signaling is crucial for the development and metastasis of several kinds of cancer. Moreover, members of the Wnt pathway have been proven to be effective biomarkers and promising cancer therapeutic targets. Abnormal stimulation of the Wnt signaling pathway has been linked to the initiation and advancement of cancer in both clinical research and in vitro investigations. A reduction in cancer incidence rate and an improvement in survival may result from targeting the Wnt/β-catenin pathway. As a result, blocking this pathway has been the focus of cancer research, and several candidates that can be targeted are currently being developed. Flavonoids derived from plants exhibit growth inhibitory, apoptotic, anti-angiogenic, and anti-migratory effects against various malignancies. Moreover, flavonoids influence different signaling pathways, including Wnt, to exert their anticancer effects. In this review, we comprehensively evaluate the influence of flavonoids on cancer development and metastasis by focusing on the Wnt/β-catenin signaling pathway, and we provide evidence of their impact on a number of molecular targets. Overall, this review will enhance our understanding of these natural products as Wnt pathway modulators.

Regulation and functions of cell division in the intestinal tissue

In multicellular organisms, epithelial cells are key elements of tissue organization. In developing epithelial tissues, cellular proliferation and differentiation are under the tight regulation of morphogenetic programs to ensure correct organ formation and functioning. In these processes, proliferation rates and division orientation regulate the speed, timing and direction of tissue expansion but also its proper patterning. Moreover, tissue homeostasis relies on spatio-temporal modulations of daughter cell behavior and arrangement. These aspects are particularly crucial in the intestine, which is one of the most proliferative tissues in adults, making it a very attractive adult organ system to study the role of cell division on epithelial morphogenesis and organ function. Although epithelial cell division has been the subject of intense research for many years in multiple models, it still remains in its infancy in the context of the intestinal tissue. In this review, we focus on the current knowledge on cell division and regulatory mechanisms at play in the intestinal epithelial tissue, as well as their importance in developmental biology and physiopathology.

Role of LGR5-positive mesenchymal cells in craniofacial development

Leucine Rich Repeat Containing G Protein-Coupled Receptor 5 (LGR5), a Wnt pathway member, has been previously recognised as a stem cell marker in numerous epithelial tissues. In this study, we used Lgr5-EGFP-CreERT2 mice to analyse the distribution of LGR5-positive cells during craniofacial development. LGR5 expressing cells were primarily located in the mesenchyme adjacent to the craniofacial epithelial structures undergoing folding, such as the nasopharyngeal duct, lingual groove, and vomeronasal organ. To follow the fate of LGR5-positive cells, we performed lineage tracing using an inducible Cre knock-in allele in combination with Rosa26-tdTomato reporter mice. The slight expansion of LGR5-positive cells was found around the vomeronasal organ, in the nasal cavity, and around the epithelium in the lingual groove. However, most LGR5 expressing cells remained in their original location, possibly supporting their signalling function for adjacent epithelium rather than exerting their role as progenitor cells for the craniofacial structures. Moreover, Lgr5 knockout mice displayed distinct defects in LGR5-positive areas, especially in the reduction of the nasopharyngeal duct, the alteration of the palatal shelves shape, abnormal epithelial folding in the lingual groove area, and the disruption of salivary gland development. The latter defect manifested as an atypical number and localisation of the glandular ducts. The gene expression of several Wnt pathway members (Rspo1-3, Axin2) was altered in Lgr5-deficient animals. However, the difference was not found in sorted EGFP-positive cells obtained from Lgr5 +/+ and Lgr5 -/- animals. Expression profiling of LGR5-positive cells revealed the expression of several markers of mesenchymal cells, antagonists, as well as agonists, of Wnt signalling, and molecules associated with the basal membrane. Therefore, LGR5-positive cells in the craniofacial area represent a very specific population of mesenchymal cells adjacent to the epithelium undergoing folding or groove formation. Our results indicate a possible novel role of LGR5 in the regulation of morphogenetic processes during the formation of complex epithelial structures in the craniofacial areas, a role which is not related to the stem cell properties of LGR5-positive cells as was previously defined for various epithelial tissues.

TROP2 Represents a Negative Prognostic Factor in Colorectal Adenocarcinoma and Its Expression Is Associated with Features of Epithelial-Mesenchymal Transition and Invasiveness

Trophoblastic cell surface antigen 2 (TROP2) is a membrane glycoprotein overexpressed in many solid tumors with a poor prognosis, including intestinal neoplasms. In our study, we show that TROP2 is expressed in preneoplastic lesions, and its expression is maintained in most colorectal cancers (CRC). High TROP2 positivity correlated with lymph node metastases and poor tumor differentiation and was a negative prognostic factor. To investigate the role of TROP2 in intestinal tumors, we analyzed two mouse models with conditional disruption of the adenomatous polyposis coli (Apc) tumor-suppressor gene, human adenocarcinoma samples, patient-derived organoids, and TROP2-deficient tumor cells. We found that Trop2 is produced early after Apc inactivation and its expression is associated with the transcription of genes involved in epithelial-mesenchymal transition, the regulation of migration, invasiveness, and extracellular matrix remodeling. A functionally similar group of genes was also enriched in TROP2-positive cells from human CRC samples. To decipher the driving mechanism of TROP2 expression, we analyzed its promoter. In human cells, this promoter was activated by β-catenin and additionally by the Yes1-associated transcriptional regulator (YAP). The regulation of TROP2 expression by active YAP was verified by YAP knockdown in CRC cells. Our results suggest a possible link between aberrantly activated Wnt/β-catenin signaling, YAP, and TROP2 expression.

Bmal1- and Per2-mediated regulation of the osteogenic differentiation and proliferation of mouse bone marrow mesenchymal stem cells by modulating the Wnt/β-catenin pathway

BACKGROUND

Bmal1 and Per2 are the core components of the circadian clock genes (CCGs). Bmal1-/- mice exhibit premature aging, as indicated by hypotrichosis and osteoporosis, with a loss of proliferation ability. The same occurs in Per2-/- mice, albeit to a less severe degree. However, whether the effects of Bmal1 and Per2 on proliferation and osteogenic differentiation are synergistic or antagonistic remains unclear. Thus, our study aimed to explore the effects and specific mechanism.

METHODS AND RESULTS

Lentiviral and adenoviral vectors were constructed to silence or overexpress Bmal1 or Per2 and MTT, flow cytometry, RT-qPCR, WB, immunohistochemistry, alizarin red staining and ChIP-Seq analyses were applied to identify the possible mechanism. The successful knockdown and overexpression of Bmal1/Per2 were detected by fluorescence microcopy. Flow cytometry found out that Bmal1 or Per2 knockdown resulted in G1-phase cell cycle arrest. RT-qPCR showed the different expression levels of Wnt-3a, c-myc1 and axin2 in the Wnt/β-catenin signaling pathway as well as the gene expression change of Rorα and Rev-erbα. Meanwhile, related proteins such as β-catenin, TCF-1, and P-GSK-3β were detected. ALP activity and the amount of mineral nodules were compared. ChIP-Seq results showed the possible mechanism.

CONCLUSIONS

Bmal1 and Per2, as primary canonical clock genes, showed synergistic effects on the proliferation and differentiation of BMSCs. They would inhibit the Wnt/β-catenin signaling pathway by downregulating Rorα expression or upregulating Rev-erbα expression, both of which were also key elements of CCGs. And this may be the mechanism by which they negatively regulate the osteogenic differentiation of BMSCs. Bmal1 and Per2 show synergistic effects in the proliferation of BMSCs. In addition, they play a synergistic role in negatively regulating the osteogenic differentiation ability of BMSCs. Bmal1 and Per2 may regulate the aging of BMSCs by altering cell proliferation and osteogenic differentiation through Rorα and Rev-erbα to affect Wnt/β-catenin pathway.

Overview of Three Proliferation Pathways (Wnt, Notch, and Hippo) in Intestine and Immune System and Their Role in Inflammatory Bowel Diseases (IBDs)

Inflammatory bowel disease (IBD) is a disorder, which involves the gastrointestinal (GI) tract consisting Crohn's disease (CD) and ulcerative colitis (UC). The etiology of this disease is not yet clear and, hence, there are numerous medications and treatments for patients with IBD, although a definite and permanent treatment is still missing. Therefore, finding novel therapeutic approaches are vital for curing patients with IBD. In the GI tract, there are various lineages of cells with different roles that their existence is necessary for the barrier function of intestinal epithelial cells (IECs). Therefore, signaling pathways, which manage the hemostasis of cell lineages in intestine, such as Wnt, Notch, and Hippo, could have crucial roles in regulation of barrier function in the intestine. Additionally, these signaling pathways function as a governor of cell growth, tissue homeostasis, and organ size. In patients with IBD, recent studies have revealed that these signaling pathways are dysregulated that it could result in depletion or excess of a cell lineage in the intestine. Moreover, dysregulation of these signaling pathways in different cell lineages of the immune system could lead to dysregulation of the immune system's responses in IBD. In this article, we summarized the components and signaling of Wnt, Notch, and Hippo pathways and their role in the intestine and immune system. Furthermore, we reviewed latest scientific literature on the crosstalk among these three signaling pathways in IBD. An overview of these three signaling pathways and their interactions in IBD could provide a novel insight for prospective study directions into finding efficient medications or treatments.

Extending the viability of human precision-cut intestinal slice model for drug metabolism studies

Human Precision-cut intestinal slices (hPCIS) are used to study intestinal physiology, pathophysiology, drug efficacy, toxicology, kinetics, and metabolism. However, the use of this ex vivo model is restricted to approximately a 24 h timeframe because of declining viability of the hPCIS during traditional culture. We hypothesized that we could extend the hPCIS viability by using organoid medium. Therefore, we cultured hPCIS for up to 72 h in organoid media [expansion medium (Emed) and differentiation medium (Dmed)]. After incubation, we assessed culture-induced changes on viability markers, specific cell type markers and we assessed the metabolic activity of enterocytes by measuring midazolam metabolite formation. We show that the adenosine triphosphate (ATP)/protein ratio of Emed-cultured hPCIS and morphology of both Emed- and Dmed-cultured hPCIS was improved compared to WME-cultured hPCIS. Emed-cultured hPCIS showed an increased expression of proliferation and stem cell markers, whereas Dmed-cultured hPCIS showed an increased expression of proliferation and enterocyte markers, along with increased midazolam metabolism. Using the Emed, the viability of hPCIS could be extended for up to 72 h, and proliferating stem cells remained preserved. Using Dmed, hPCS also remained viable for up to 72 h, and specifically rescued the metabolizing enterocytes during culture. In conclusion, by using two different organoid culture media, we could extend the hPCIS viability for up to 72 h of incubation and specifically steer stem cells or enterocytes towards their original function, metabolism, and proliferation, potentially allowing pharmacokinetic and toxicology studies beyond the 24 h timeframe.

Dietary Inclusion of Seabuckthorn (Hippophae rhamnoides) Mitigates Foodborne Enteritis in Zebrafish Through the Gut-Liver Immune Axis

To help prevent foodborne enteritis in aquaculture, several feed additives, such as herbal medicine, have been added to fish diets. Predictions of effective herb medicines for treating fish foodborne enteritis from key regulated DEGs (differentially expressed genes) in transcriptomic data can aid in the development of feed additives using the Traditional Chinese Medicine Integrated Database. Seabuckthorn has been assessed as a promising candidate for treating grass carp soybean-induced enteritis (SBMIE). In the present study, the SBMIE zebrafish model was used to assess seabuckthorn's therapeutic or preventative effects. The results showed that intestinal and hepatic inflammation was reduced when seabuckthorn was added, either pathologically (improved intestinal villi morphology, less oil-drops) or growth-related (body fat deposition). Moreover, seabuckthorn may block the intestinal p53 signaling pathway, while activating the PPAR signaling pathway and fatty acid metabolism in the liver. 16S rRNA gene sequencing results also indicated a significant increase in OTU numbers and skewed overlapping with the fish meal group following the addition of seabuckthorn. Additionally, there were signs of altered gut microbiota taxa composition, particularly for reduced TM7, Sphingomonas, and Shigella, following the addition of seabuckthorn. Hindgut imaging of fluorescent immune cells in SBMIE larvae revealed the immune regulatory mechanisms at the cellular level. Seabuckthorn may significantly inhibit the inflammatory gathering of neutrophils, macrophages, and mature T cells, as well as cellular protrusions' formation. On the other hand, in larvae, seabuckthorn inhibited the inflammatory aggregation of lck+ T cells but not immature lymphocytes, indicating that it affected intestinal adaptive immunity. Although seabuckthorn did not affect the distribution of intestinal CD4+ cells, the number of hepatic CD4+ cells were reduced in fish from the seabuckthorn supplementation group. Thus, the current data indicate that seabuckthorn may alleviate foodborne gut-liver symptoms by enhancing intestinal mucosal immunity and microbiota while simultaneously inhibiting hepatic adipose disposition, making it a potential additive for preventing fish foodborne gut-liver symptoms.

Intestinal Wnt in the transition from physiology to oncology

Adult stem cells are necessary for self-renewal tissues and regeneration after damage. Especially in the intestine, which self-renews every few days, they play a key role in tissue homeostasis. Therefore, complex regulatory mechanisms are needed to prevent hyperproliferation, which can lead in the worst case to carcinogenesis or under-activation of stem cells, which can result in dysfunctional epithelial. One main regulatory signaling pathway is the Wnt/β-catenin signaling pathway. It is a highly conserved pathway, with β-catenin, a transcription factor, as target protein. Translocation of β-catenin from cytoplasm to nucleus activates the transcription of numerous genes involved in regulating stem cell pluripo-tency, proliferation, cell differentiation and regulation of cell death. This review presents a brief overview of the Wnt/β-catenin signaling pathway, the regulatory mechanism of this pathway and its role in intestinal homeostasis. Additionally, this review highlights the molecular mechanisms and the histomorphological features of Wnt hyperactivation. Furthermore, the central role of the Wnt signaling pathway in intestinal carcinogenesis as well as its clinical relevance in colorectal carcinoma are discussed.

PERCC1, a new member of the Yap/TAZ/FAM181 transcriptional co-regulator family

Motivation

Disrupted PERCC1 gene expression causes an intractable congenital diarrhoea in infants. However, this gene's molecular mechanism is unknown and no homologous proteins have been reported.

Results

Our detailed evolutionary analysis of PERCC1 sequence reveals it to be a previously unappreciated member of the YAP/TAZ/FAM181 family of homologous transcriptional regulators. Like YAP and TAZ, PERCC1 likely interacts with DNA via binding to TEA/ATTS domain transcription factors (TEADs) using its conserved interface-2 and -3 sequences. We compare the expression patterns of PERCC1 with those of YAP, TAZ, TEADs. Our report provides the identification and first in-depth bioinformatic analysis of a YAP/TAZ homologue, and a likely new regulator of the YAP/TAZ-TEAD transcriptional complex.

Availability and implementation

The data underlying this article are available in UniProt Database.

Supplementary information

Supplementary data are available at Bioinformatics Advances online.

Role of YAP1 Signaling in Biliary Development, Repair, and Disease

Yes-associated protein 1 (YAP1) is a transcriptional coactivator that activates transcriptional enhanced associate domain transcription factors upon inactivation of the Hippo signaling pathway, to regulate biological processes like proliferation, survival, and differentiation. YAP1 is most prominently expressed in biliary epithelial cells (BECs) in normal adult livers and during development. In the current review, we will discuss the multiple roles of YAP1 in the development and morphogenesis of bile ducts inside and outside the liver, as well as in orchestrating the cholangiocyte repair response to biliary injury. We will review how biliary repair can occur through the process of hepatocyte-to-BEC transdifferentiation and how YAP1 is pertinent to this process. We will also discuss the liver's capacity for metabolic reprogramming as an adaptive mechanism in extreme cholestasis, such as when intrahepatic bile ducts are absent due to YAP1 loss from hepatic progenitors. Finally, we will discuss the roles of YAP1 in the context of pediatric pathologies afflicting bile ducts, such as Alagille syndrome and biliary atresia. In conclusion, we will comprehensively discuss the spatiotemporal roles of YAP1 in biliary development and repair after biliary injury while describing key interactions with other well-known developmental pathways.

HIPPO signaling-related signature for predicting prognosis and therapeutic response in gastric cancer

Background: Gastric cancer (GC) is a multifactorial progressive disease with high mortality and heterogeneous prognosis. Effective prognostic biomarkers for GC were critically needed. Hippo signaling pathway is one of the critical mechanisms regulating the occurrence and development of GC, and has potential clinical application value for the prognosis and treatment of GC patients. However, there is no effective signature based on Hippo signaling pathway-related genes (HSPRGs) to predict the prognosis and treatment response of GC patients. Our study aimed to build a HSPRGs signature and explore its performance in improving prognostic assessment and drug therapeutic response in GC. Methods: Based on gene expression profiles obtained from The Cancer Genome Atlas (TCGA) database, we identified differentially expressed HSPRGs and conducted univariate and the least absolute shrinkage and selection operator (LASSO) Cox regression analysis to construct a multigene risk signature. Subsequently, the Kaplan-Meier curve and receiver operating characteristic (ROC) were performed to evaluate the predictive value of the risk signature in both training and validation cohort. Furthermore, we carried out univariate and multivariate Cox regression analysis to investigate the independent prognostic factors and establish a predictive nomogram. The enriched signaling pathways in risk signature were analyzed by gene set enrichment analysis (GSEA). Tumor immune dysfunction and exclusion (TIDE) and drug sensitivity analysis were performed to depict therapeutic response in GC. Results: In total, 38 differentially expressed HSPRGs were identified, and final four genes (DLG3, TGFB3, TGFBR1, FZD6) were incorporated to build the signature. The ROC curve with average 1-, 3-, and 5-year areas under the curve (AUC) equal to .609, .634, and .639. Clinical ROC curve revealed that risk signature was superior to other clinicopathological factors in predicting prognosis. Calibration curves and C-index (.655) of nomogram showed excellent consistency. Besides, in the immunotherapy analysis, exclusion (p < 2.22 × 10^-16) and microsatellite instability (p = .0058) performed significantly differences. Finally, our results suggested that patients in the high-risk group were more sensitive to specific chemotherapeutic agents. Conclusion: Results support the hypothesis that Hippo-related signature is a novel prognostic biomarker and predictor, which could help optimize GC prognostic stratification and inform clinical medication decisions.

Qingchang Wenzhong Decoction Accelerates Intestinal Mucosal Healing Through Modulation of Dysregulated Gut Microbiome, Intestinal Barrier and Immune Responses in Mice

Inflammatory bowel disease (IBD), a group of multifactorial and inflammatory infirmities, is closely associated with dysregulation of gut microbiota and host metabolome, but effective treatments are currently limited. Qingchang Wenzhong Decoction (QCWZD) is an effective and classical traditional herbal prescription for the treatment of IBD and has been proved to attenuate intestinal inflammation in a model of acute colitis. However, the role of QCWZD in recovery phase of colitis is unclear. Here, we demonstrated that mice treated with QCWZD showed a faster recovery from dextran sulfate sodium (DSS)-induced epithelial injury, accompanied by reduced mucosal inflammation and attenuated intestinal dysbiosis using bacterial 16S rRNA amplicon sequencing compared to those receiving sterile water. The protective effects of QCWZD are gut microbiota dependent, as demonstrated by fecal microbiome transplantation and antibiotics treatment. Gut microbes transferred from QCWZD-treated mice displayed a similar role in mucosal protection and epithelial regeneration as QCWZD on colitis in mice, and depletion of the gut microbiota through antibiotics treatments diminished the beneficial effects of QCWZD on colitis mice. Moreover, metabolomic analysis revealed metabolic profiles alternations in response to the gut microbiota reprogrammed by QCWZD intervention, especially enhanced tryptophan metabolism, which may further accelerate intestinal stem cells-mediated epithelial regeneration to protect the integrity of intestinal mucosa through activation of Wnt/β-catenin signals. Collectively, our results suggested that orally administrated QCWZD accelerates intestinal mucosal healing through the modulation of dysregulated gut microbiota and metabolism, thus regulating intestinal stem cells-mediated epithelial proliferation, and hold promise for novel microbial-based therapies in the treatment of IBD.

miR‑125a‑5p reverses epithelial‑mesenchymal transition and restores drug sensitivity by negatively regulating TAFAZZIN signaling in breast cancer

MicroRNA (miR)‑125a‑5p represses tafazzin phospholipid‑lysophospholipid transacylases (TAFAZZIN) expression and inhibits the epithelial‑mesenchymal transition (EMT) of ovarian cancer cells. EMT was found to have a crucial role in the acquisition of chemoresistance. Thus, the present study aimed to determine whether miR‑125a‑5p reverses EMT and restores drug sensitivity by negatively regulating TAFAZZIN in breast cancer. The expression of miR‑125a‑5p/TAFAZZIN and its association with chemotherapy response were determined in tissue samples from patients with breast cancer. Furthermore, the effects of miR‑125a‑5p on breast cancer cells were elucidated using cell proliferation and cell apoptosis assays. Then, the regulatory mechanism of miR‑125a‑5p in breast cancer was investigated by reverse transcription‑quantitative PCR, western blotting, dual‑luciferase reporter and RNA immunoprecipitation assays. The results demonstrated that miR‑125a‑5p inhibited the EMT of MCF‑7/adriamycin (Adr) breast cancer cells, as well as decreased the proliferation and increased the apoptosis of breast cancer cells treated with Adr/docetaxel. In addition, miR‑125a‑5p downregulated the expression levels of TAFAZZIN, Transglutaminase 2, phosphorylated‑AKT, N‑cadherin, vimentin and proliferating cell nuclear antigen, and significantly increased those of E‑cadherin, cleaved caspase-3 and Bax in MCF7/Adr cells. Similar results were obtained with small interfering RNA‑TAFAZZIN. Moreover, TAFAZZIN was identified as a direct target of miR‑125a‑5p in MCF7/Adr breast cancer cells. In addition, increased miR‑125a‑5p expression was observed in breast tumors from patients exhibiting a chemotherapy response, and TAFAZZIN mRNA expression was elevated in patients with no chemotherapy response. Hence, miR‑125a‑5p expression was negatively correlated with TAFAZZIN mRNA expression in breast cancer tissues. All these data suggested that miR‑125a‑5p reverses EMT and restores drug sensitivity by negatively regulating TAFAZZIN in breast cancer and, therefore, has potential as a novel therapeutic target for this disease.

Yes-associated protein expression is associated with poor prognosis in patients with colorectal cancer

Colorectal cancer (CRC) is the third leading cause of cancer-related death worldwide. The aim of the present study was to investigate the expression of yes-associated protein (YAP) in CRC tissues, and to determine the relationship between the expression levels of YAP and the clinicopathological characteristics and prognosis of patients with CRC. Bioinformatics analysis was conducted to examine the expression of YAP and its correlation with clinicopathological characteristics and key genes, using functional enrichment analysis. Immunohistochemistry was used to detect YAP expression in 181 CRC tissue samples and 30 normal colorectal mucosa samples. Western blotting and reverse transcription-quantitative PCR were performed to detect the expression of YAP and β-catenin in CRC cells, and cellular proliferation was assessed using a Cell Counting Kit-8 assay. Finally, apoptosis was analyzed using flow cytometry. Immunohistochemical staining indicated that the positive expression rate of YAP in CRC tissues was 73.5%, which was significantly higher than that in normal colorectal mucosa samples. The expression of YAP in CRC was associated with histological differentiation, lymph node metastasis and Duke's stage. However, no significant associations were observed between YAP expression and age, sex and T stage. Downregulation of YAP promoted the proliferation and the inhibited apoptosis of CRC cells, and YAP expression was positively correlated with that of β-catenin in both CRC tissues and cells. Furthermore, YAP expression was upregulated in CRC tissues, which was correlated with tumor progression and prognosis. Therefore, YAP expression may be used as an independent predictor of poor prognosis in patients with CRC, and the underling molecular mechanism may be associated with the combined effect of Hippo and Wnt/β-catenin signaling.

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.

Inhibition of cyclooxygenase-2 enhanced intestinal epithelial homeostasis via suppressing β-catenin signalling pathway in experimental liver fibrosis

The intestinal barrier dysfunction is crucial for the development of liver fibrosis but can be disturbed by intestinal chronic inflammation characterized with cyclooxygenase‐2 (COX‐2) expression. This study focused on the unknown mechanism by which COX‐2 regulates intestinal epithelial homeostasis in liver fibrosis. The animal models of liver fibrosis induced with TAA were established in rats and in intestinal epithelial–specific COX‐2 knockout mice. The impacts of COX‐2 on intestinal epithelial homeostasis via suppressing β‐catenin signalling pathway were verified pharmacologically and genetically in vivo. A similar assumption was tested in Ls174T cells with goblet cell phenotype in vitro. Firstly, disruption of intestinal epithelial homeostasis in cirrhotic rats was ameliorated by celecoxib, a selective COX‐2 inhibitor. Then, β‐catenin signalling pathway in cirrhotic rats was associated with the activation of COX‐2. Furthermore, intestinal epithelial–specific COX‐2 knockout could suppress β‐catenin signalling pathway and restore the disruption of ileal epithelial homeostasis in cirrhotic mice. Moreover, the effect of COX‐2/PGE2 was dependent on the β‐catenin signalling pathway in Ls174T cells. Therefore, inhibition of COX‐2 may enhance intestinal epithelial homeostasis via suppression of the β‐catenin signalling pathway in liver fibrosis.

New insights into the important roles of tumor cell-intrinsic PD-1

PD-1 (Programmed cell death protein-1) is mainly expressed in various immune cells, while its ligands PD-L1/PD-L2 (Programmed death ligand-1/Programmed death ligand-2) are mostly expressed in tumor cells. Generally, the binding of PD-L1/PD-L2 and PD-1 could lead to the tumor immune evasion. However, some recent studies showed that PD-1 could also be expressed in tumor cells and could activate mTOR (Mammalian Target of Rapamycin) or Hippo signaling pathway, therefore facilitating tumor proliferation independent of the immune system. While there was evidence that tumor cell-intrinsic PD-1 inhibited the activation of AKT and ERK1/2 pathways, thereby inhibiting tumor cell growth. Based on TCGA and CCLE database, we found that PD-1 was expressed in a variety of tumors and was associated with patient's prognosis. Besides, we found that PD-1 may be involved in many carcinogenic signaling pathway on the basis of PD-1 gene enrichment analysis of cancer tissues and cancer cells. Our understanding of the tumor cell-intrinsic PD-1 function is still limited. This review is aimed at elaborating the potential effects of tumor cell-intrinsic PD-1 on carcinogenesis, providing a novel insight into the effects of anti-PD-1/PD-L1 immunotherapy, and helping to open a major epoch of combination therapy.

Rspo3 regulates the abnormal differentiation of small intestinal epithelial cells in diabetic state

Background

The complications caused by diabetes mellitus (DM) are the focus of clinical treatment. However, little is known about diabetic enteropathy (DE) and its potential underlying mechanism.

Methods

Intestinal epithelial cells (IECs) and intestinal epithelial stem cells (IESCs) were harvested from BKS.Cg-Dock7^m+/+Lepr^db/JNju (DM) mice, and the expression of R-Spondin 3 (Rspo3) was detected by RT-qPCR, Western blotting, immunohistochemistry, and immunofluorescence. The role of Rspo3 in the abnormal differentiation of IECs during DM was confirmed by knockdown experiments. Through miRNA expression profiling, bioinformatics analysis, and RT-qPCR, we further analyzed the differentiation-related miRNAs in the IECs from mice with DM.

Results

Abnormal differentiation of IECs was observed in the mice with DM. The expression of Rspo3 was upregulated in the IECs from the mice with DM. This phenomenon was associated with Rspo3 overexpression. Additionally, Rspo3 is a major determinant of Lgr5+ stem cell identity in the diabetic state. Microarray analysis, bioinformatics analysis, and luciferase reporter assays revealed that microRNA (miR)-380-5p directly targeted Rspo3. Moreover, miR-380-5p upregulation was observed to attenuate the abnormal differentiation of IECs by regulating Rspo3 expression.

Conclusions

Together, our results provide definitive evidence of the essential role of Rspo3 in the differentiation of IECs in DM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02385-8.

Mutant Presenilin 1 Dysregulates Exosomal Proteome Cargo Produced by Human-Induced Pluripotent Stem Cell Neurons

The accumulation and propagation of hyperphosphorylated tau (p-Tau) is a neuropathological hallmark occurring with neurodegeneration of Alzheimer's disease (AD). Extracellular vesicles, exosomes, have been shown to initiate tau propagation in the brain. Notably, exosomes from human-induced pluripotent stem cell (iPSC) neurons expressing the AD familial A246E mutant form of presenilin 1 (mPS1) are capable of inducing tau deposits in the mouse brain after in vivo injection. To gain insights into the exosome proteome cargo that participates in propagating tau pathology, this study conducted proteomic analysis of exosomes produced by human iPSC neurons expressing A246E mPS1. Significantly, mPS1 altered the profile of exosome cargo proteins to result in (1) proteins present only in mPS1 exosomes and not in controls, (2) the absence of proteins in the mPS1 exosomes which were present only in controls, and (3) shared proteins which were upregulated or downregulated in the mPS1 exosomes compared to controls. These results show that mPS1 dysregulates the proteome cargo of exosomes to result in the acquisition of proteins involved in the extracellular matrix and protease functions, deletion of proteins involved in RNA and protein translation systems along with proteasome and related functions, combined with the upregulation and downregulation of shared proteins, including the upregulation of amyloid precursor protein. Notably, mPS1 neuron-derived exosomes displayed altered profiles of protein phosphatases and kinases involved in regulating the status of p-tau. The dysregulation of exosome cargo proteins by mPS1 may be associated with the ability of mPS1 neuron-derived exosomes to propagate tau pathology.

Mechanism of MicroRNA-375 Promoter Methylation in Promoting Ovarian Cancer Cell Malignancy

Objective:

Ovarian cancer (OC) ranks one of the most prevalent fatal tumors of female genital organs. Aberrant promoter methylation triggers changes of microRNA (miR)-375 in OC. Our study aimed to evaluate the mechanism of methylated miR-375 promoter region in OC cell malignancy and to seek the possible treatment for OC.

Methods:

miR-375 promoter methylation level in OC tissues and cells was detected. miR-375 expression in OC tissues and cell lines was compared with that in demethylated cells. Role of miR-375 in OC progression was measured. Dual-luciferase reporter gene assay was utilized to verify the targeting relationship between miR-375 and Yes-associated protein 1 (YAP1). Then, Wnt/β-catenin pathway-related protein expression was tested. Moreover, xenograft transplantation was applied to confirm the in vitro experiments.

Results:

Highly methylated miR-375 was seen in OC tissues and cell lines, while its expression was decreased as the promoter methylation increased. Demethylation in OC cells brought miR-375 back to normal level, with obviously declined cell invasion, migration and viability and improved apoptosis. Additionally, miR-375 targeted YAP1 to regulate the Wnt/β-catenin pathway protein expression. Overexpressed YAP1 reversed the protein expression, promoted cell invasion, migration and viability while reduced cell apoptosis. Overexpressed miR-375 in vivo inhibited OC progression.

Conclusion:

Our study demonstrated that demethylated miR-375 inhibited OC growth by targeting YAP1 and downregulating the Wnt/β-catenin pathway. This investigation may offer novel insight for OC treatment.

Porcine colonoids and enteroids keep the memory of their origin during regeneration

The development of alternative in vitro culture methods has increased in the last decade as three-dimensional organoids of various tissues, including those of the small and large intestines. Due to their multicellular composition, organoids offer advantages over traditionally used immortalized or primary cell lines. However, organoids must be accurate models of their tissues of origin. This study compared gene expression profiles with respect to markers of specific cell types (stem cells, enterocytes, goblet, and enteroendocrine cells) and barrier maturation (tight junctions) of colonoid and enteroid cultures with their tissues of origin and colonoids with enteroids. Colonoids derived from three healthy pigs formed multilobed structures with a monolayer of cells similar to the crypt structures in colonic tissue. Colonoid and enteroid gene expression signatures were more similar to those found for the tissues of their origin than to each other. However, relative to their derived tissues, organoids had increased gene expression levels of stem cell markers Sox9 and Lgr5 encoding sex-determining region Y-box 9 and leucine-rich repeat-containing G protein-coupled rector 5, respectively. In contrast, expression levels of Occl and Zo1 encoding occludin and zonula occludens 1, respectively, were decreased. Expression levels of the cell lineage markers Atoh1, Cga, and Muc2 encoding atonal homolog 1, chromogranin A, and mucin 2, respectively, were decreased in colonoids, whereas Sglt1 and Apn encoding sodium-glucose transporter 1 and aminopeptidase A, respectively, were decreased in enteroids. These results indicate colonoid and enteroid cultures were predominantly comprised of undifferentiated cell types with decreased barrier maturation relative to their tissues of origin.

Ubiquitin ligases and medulloblastoma: genetic markers of the four consensus subgroups identified through transcriptome datasets

The ubiquitin proteasome system regulates key cellular processes in normal and in cancer cells. Herein, we review published data on the role of ubiquitin ligases in the four major subgroups of medulloblastoma (MB). While conventional literature serves as an initial source of information on cellular pathways in MB, large publicly available datasets of gene expression can be used to add information not previously identified in the literature. By analysing the publicly available Cavalli dataset, we show that increased expression of ZNRF3 characterizes the WNT subgroup of MB. The ZNRF3 gene codes for an E3 ligase associated with WNT receptors. Loss of a copy of chromosome 6 in a subtype of the WNT group was associated with decreased expression of the gene encoding the E3 ligase RNF146. While the E3 ligase SMURF regulates SHH receptors, increased expression of the gene encoding the Cullin Ring E3 adaptor PPP2R2C was statistically a better genetic marker of the SHH group. Genes whose expression was statistically strongly related to Group 3 included the E3 ligase gene TRIM58, and the gene for the E3 ligase adaptor, PPP2R2B. Group 4 MB was associated with expression of genes encoding several E3 ligases and E3 ligase adaptors involved in ribosome biogenesis. Increased expression of the genes encoding the E3 ligase adaptors and transcription repressors ZBTB18 and ZBTB38 were also noted in subgroup 4. These data suggest that several E3 ligases and their adaptors should be investigated as therapeutic targets for subgroup specific MB brain tumors.

Canonical WNT/β-Catenin Signaling Activated by WNT9b and RSPO2 Cooperation Regulates Facial Morphogenesis in Mice

The R-spondin (RSPO) family of proteins potentiate canonical WNT/β-catenin signaling and may provide a mechanism to fine-tune the strength of canonical WNT signaling. Although several in vitro studies have clearly demonstrated the potentiation of canonical WNT signaling by RSPOs, whether this potentiation actually occurs in normal development and tissue function in vivo still remains poorly understood. Here, we provide clear evidence of the potentiation of canonical WNT signaling by RSPO during mouse facial development by analyzing compound Wnt9b and Rspo2 gene knockout mice and utilizing ex vivo facial explants. Wnt9b;Rspo2 double mutant mice display facial defects and dysregulated gene expression pattern that are significantly more severe than and different from those of Wnt9b or Rspo2 null mutant mice. Furthermore, we found suggestive evidence that the LGR4/5/6 family of the RSPO receptors may play less critical roles in WNT9b:RSPO2 cooperation. Our results suggest that RSPO-induced cooperation is a key mechanism for fine-tuning canonical WNT/β-catenin signaling in mouse facial development.

Human Colorectal Cancer from the Perspective of Mouse Models

Colorectal cancer (CRC) is a heterogeneous disease that includes both hereditary and sporadic types of tumors. Tumor initiation and growth is driven by mutational or epigenetic changes that alter the function or expression of multiple genes. The genes predominantly encode components of various intracellular signaling cascades. In this review, we present mouse intestinal cancer models that include alterations in the Wnt, Hippo, p53, epidermal growth factor (EGF), and transforming growth factor β (TGFβ) pathways; models of impaired DNA mismatch repair and chemically induced tumorigenesis are included. Based on their molecular biology characteristics and mutational and epigenetic status, human colorectal carcinomas were divided into four so-called consensus molecular subtype (CMS) groups. It was shown subsequently that the CMS classification system could be applied to various cell lines derived from intestinal tumors and tumor-derived organoids. Although the CMS system facilitates characterization of human CRC, individual mouse models were not assigned to some of the CMS groups. Thus, we also indicate the possible assignment of described animal models to the CMS group. This might be helpful for selection of a suitable mouse strain to study a particular type of CRC.

PTPRU, As A Tumor Suppressor, Inhibits Cancer Stemness By Attenuating Hippo/YAP Signaling Pathway

Background

PTPRU is an important signaling molecule that regulates a variety of cellular processes; however, the role of PTPRU in cancer development has remained elusive. Here, we report that PTPRU serves as a tumor suppressor that inhibits cancer stemness by attenuating Hippo/YAP signaling pathway.

Methods

Primary cancer cells and cell line cells were used in the study. The gene expression data were downloaded from R2 analysis and visualization platform and Kaplan–Meier analysis was performed to study the relationship between survival and PTPRU expression. qRT-PCR and Western blot were employed to study the expression of target genes in tissues and cells. Sphere and colony formation, proliferation, migration activities and the expression of stem cell and EMT markers were employed for characterizing the stemness. Gene manipulation was achieved by lentivirus-mediated gene delivery system. Luciferase reporter gene assay was used to study the transcriptional activity of the promoter, and ChIP-qPCR was employed to study the target binding sequence of the protein. Spearman correlation analysis was performed to study the correlation between two genes. Student’s t-test was used for determination of the significance between two experimental groups.

Results

PTPRU is downregulated in colorectal and gastric cancer tissues and cancer stem cells. High expression of PTPRU predicts poor prognosis. Overexpression of PTPRU attenuates the stemness of gastric cancer stem cells and knockdown of PTRPU improves the maintenance of the stemness of cancer stem cells. Mechanistic analysis showed that PTPRU inhibits Hippo/YAP signaling by suppressing the expression of YAP in a transcriptional level. Overexpression of YAP restored PTPRU-induced inhibited stemness of gastric cancer stem cells.

Conclusion

PTPRU serves as a tumor suppressor that inhibits the stemness of cancer stem cell by inhibiting Hippo/YAP signaling pathway.

Intracellular Signals Activated by Canonical Wnt Ligands Independent of GSK3 Inhibition and β-Catenin Stabilization

In contrast to non-canonical ligands, canonical Wnts promote the stabilization of β-catenin, which is a prerequisite for formation of the TCF4/β-catenin transcriptional complex and activation of its target genes. This pathway is initiated by binding of Wnt ligands to the Frizzled/LRP5/6 receptor complex, and it increases the half-life of β-catenin by precluding the phosphorylation of β-catenin by GSK3 and its binding to the βTrCP1 ubiquitin ligase. Other intercellular signals are also activated by Wnt ligands that do not inhibit GSK3 and increase β-catenin protein but that either facilitate β-catenin transcriptional activity or stimulate other transcriptional factors that cooperate with it. In this review, we describe the layers of complexity of these signals and discuss their crosstalk with β-catenin in activation of transcriptional targets.

Role and molecular mechanism of stem cells in colorectal cancer initiation

In recent years, the rate of colorectal cancer has sharply increased, especially in China, where it ranks second for the number of cancer fatalities. Currently, the treatment of colorectal cancer patients involves the combination of resection surgery and treatment with postoperative anticancer drugs such as 5-FU and oxaliplatin. However, recurrence and metastasis after treatment are still the dominant reasons for the low survival rate. Colorectal cancer stem cells (CSCs) are regarded as the key contributors to tumour recurrence and metastasis due to their resistance to chemotherapy drugs and their extremely high tumourigenicity. Once CSCs overcome chemotherapy treatment, they continue to survive and reinitiate proliferation to form tumours, leading to recurrence. The dominant reason for CSC resistance is that most anticancer drugs are aimed at inhibiting proliferative pathways in cancer cells that differ from those in CSCs. Therefore, studies on the characteristics of CSCs and their intracellular molecular pathways are essential for the exploration of CSC-targeted drugs. In this report, we review recent advances in the research of CSCs and, in particular, review the important intracellular molecular pathways, such as HOXA5-catenin, STRAP-NOTCH and YAP/TAZ, related to the maintenance and differentiation of stem cells to generate a theoretical basis for the exploration of CSC-targeted drugs.

HNF4α and CDX2 Regulate Intestinal YAP1 Promoter Activity

The Hippo pathway is important for tissue homeostasis, regulation of organ size and growth in most tissues. The co-transcription factor yes-associated protein 1 (YAP1) serves as a main downstream effector of the Hippo pathway and its dysregulation increases cancer development and blocks colonic tissue repair. Nevertheless, little is known about the transcriptional regulation of YAP1 in intestinal cells. The aim of this study to identify gene control regions in the YAP1 gene and transcription factors important for intestinal expression. Bioinformatic analysis of caudal type homeobox 2 (CDX2) and hepatocyte nuclear factor 4 alpha (HNF4α) chromatin immunoprecipitated DNA from differentiated Caco-2 cells revealed potential intragenic enhancers in the YAP1 gene. Transfection of luciferase-expressing YAP1 promoter-reporter constructs containing the potential enhancer regions validated one potent enhancer of the YAP1 promoter activity in Caco-2 and T84 cells. Two potential CDX2 and one HNF4α binding sites were identified in the enhancer by in silico transcription factor binding site analysis and protein-DNA binding was confirmed in vitro using electrophoretic mobility shift assay. It was found by chromatin immunoprecipitation experiments that CDX2 and HNF4α bind to the YAP1 enhancer in Caco-2 cells. These results reveal a previously unknown enhancer of the YAP1 promoter activity in the YAP1 gene, with importance for high expression levels in intestinal epithelial cells. Additionally, CDX2 and HNF4α binding are important for the YAP1 enhancer activity in intestinal epithelial cells.

Exosomes, metastases, and the miracle of cancer stem cell markers

Cancer-initiating cells (CIC) are the driving force in tumor progression. There is strong evidence that CIC fulfill this task via exosomes (TEX), which modulate and reprogram stroma, nontransformed cells, and non-CIC. Characterization of CIC, besides others, builds on expression of CIC markers, many of which are known as metastasis-associated molecules. We here discuss that the linkage between CIC/CIC-TEX and metastasis-associated molecules is not fortuitously, but relies on the contribution of these markers to TEX biogenesis including loading and TEX target interactions. In addition, CIC markers contribute to TEX binding- and uptake-promoted activation of signaling cascades, transcription initiation, and translational control. Our point of view will be outlined for pancreas and colon CIC highly expressing CD44v6, Tspan8, EPCAM, claudin7, and LGR5, which distinctly but coordinately contribute to tumor progression. Despite overwhelming progress in unraveling the metastatic cascade and the multiple tasks taken over by CIC-TEX, there remains a considerable gap in linking CIC biomarkers, TEX, and TEX-initiated target modulation with metastasis. We will try to outline possible bridges, which could allow depicting pathways for new and expectedly powerful therapeutic interference with tumor progression.

Genetic ablation of TAZ induces HepG2 liver cancer cell apoptosis through activating the CaMKII/MIEF1 signaling pathway

Background and objective

Transcriptional coactivator with PDZ-binding motif (TAZ) has been found to be associated with tumor progression. Mitochondrial homeostasis regulates cancer cell viability and metastasis. However, the roles of TAZ and mitochondrial homeostasis in liver cancer viability have not been explored. The aim of our study was to investigate the influence of TAZ on HepG2 liver cancer cell apoptosis.

Materials and methods

HepG2 liver cancer cell was used in the present study, and shRNA against TAZ was transfected into HepG2 cell to knockdown TAZ expression. Mitochondrial function was analyzed using Western blotting, immunofluorescence assay, and flow cytometry. Pathway blocker was used to confirm the role of CaMKII pathway in TAZ-mediated cancer cell death.

Results

Our results indicated that TAZ deletion induced death in HepG2 cell via apoptosis. Biological analysis demonstrated that mitochondrial stress, including mitochondrial bioenergetics disorder, mitochondrial oxidative stress, and mitochondrial apoptosis, were activated by TAZ deletion. Furthermore, we found that TAZ affected mitochondrial stress by triggering mitochondrial elongation factor 1 (MIEF1)-related mitochondrial dysfunction. The loss of MIEF1 sustained mitochondrial function and promoted cancer cell survival. Molecular investigation illustrated that TAZ regulated MIEF1 expression via the CaMKII signaling pathway. Blockade of the CaMKII pathway prevented TAZ-mediated MIEF1 upregulation and improved cancer cell survival.

Conclusion

Taken together, our results highlight the key role of TAZ as a master regulator of HepG2 liver cancer cell viability via the modulation of MIEF1-related mitochondrial stress and the CaMKII signaling pathway. These findings define TAZ and MIEF1-related mitochondrial dysfunction as tumor suppressors that act by promoting cancer apoptosis via the CaMKII signaling pathway, with potential implications for new approaches to liver cancer therapy.

The protective roles of NLRP6 in intestinal epithelial cells

The evolution of chronic inflammatory diseases is thought to be due to a combination of host genetic variations and environmental factors that include the alteration of intestinal flora, termed "dysbiosis." The intestinal mucosal barrier includes a chemical barrier and physical barrier that have important roles in protecting the intestine against inflammatory injury. The chemical barrier includes antimicrobial peptides (AMPs), and the physical barrier includes a mucous layer, a monolayer of intestinal epithelial cells and cell junctions. The intestinal mucosal barrier is not a static barrier, but rather, it strongly interacts with the gut microbiome and cells of the immune system. Correct expression of AMPs, together with mucus and balanced epithelial cell proliferation, prevents the occurrence of disease. NLRP6, a member of the nucleotide-binding domain, leucine-rich repeat-containing (NLR) innate immune receptor family, participates in the progression of intestinal inflammation and enteric pathogen infections. It has become apparent in recent years that NLRP6 is important in disease pathogenesis, as it responds to internal ligands that lead to the release of AMPs and mucus, thus regulating the regeneration of intestinal epithelial cells. This review summarizes the activation of NLRP6 and its protective role in the intestinal epithelial cell.

Yes-Associated Protein 1 as a Novel Prognostic Biomarker for Gastrointestinal Cancer: A Meta-Analysis

Background

Yes-associated protein 1 (YAP1) is an effector of Hippo pathway, which plays a significant role in cell proliferation and tumor progression. The relationship between YAP1 and gastrointestinal cancer has been explored in many previous studies. We conducted a meta-analysis to explore the prognostic effect of YAP1 in patients with gastrointestinal cancer.

Methods

A systematic search was performed through the PubMed, Web of Science, Embase, and Cochrane library databases to collect eligible studies. The pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were used to evaluate the relationship between YAP1 expression and gastrointestinal cancer clinical outcomes.

Results

A total of 2941 patients from 18 studies were enrolled. The results showed that elevated YAP1 expression predicted a poor prognosis in gastrointestinal cancer (HR = 1.56; 95% CI: 1.29-1.89; P < 0.001). Subgroup analyses indicated significant association between YAP1 overexpression and shorter OS of patients with esophageal squamous cell carcinoma (HR = 1.85; 95% CI: 1.25-2.73; P = 0.002), gastric cancer (HR = 1.41,95% CI: 1.02-1.95; P = 0.037), and colorectal cancer (pooled HR = 1.75; 95% CI: 1.42-2.15; P < 0.001). However, YAP1 expression did not affect DFS of patients with gastrointestinal cancer (pooled HR = 1.33; 95% CI: 0.95-1.88; P = 0.101).

Conclusion

Elevated YAP1 expression in patients with gastrointestinal cancer might be related to shorter OS. YAP1 protein could serve as a potential predictor of poor prognosis in gastrointestinal cancer.

Wnt Signalling in Intestinal Stem Cells: Lessons from Mice and Flies

Adult stem cells play critical roles in the basal maintenance of tissue integrity, also known as homeostasis, and in tissue regeneration following damage. The highly conserved Wnt signalling pathway is a key regulator of stem cell fate. In the gastrointestinal tract, Wnt signalling activation drives homeostasis and damage-induced repair. Additionally, deregulated Wnt signalling is a common hallmark of age-associated tissue dysfunction and cancer. Studies using mouse and fruit fly models have greatly improved our understanding of the functional contribution of the Wnt signalling pathway in adult intestinal biology. Here, we summarize the latest knowledge acquired from mouse and Drosophila research regarding canonical Wnt signalling and its key functions during stem cell driven intestinal homeostasis, regeneration, ageing and cancer.