Mechanistic insights from structural studies of β-catenin and its binding partners

Mechanistic insights into Wnt-β-catenin pathway activation and signal transduction

In multicellular organisms, Wnt proteins govern stem and progenitor cell renewal and differentiation to regulate embryonic development, adult tissue homeostasis and tissue regeneration. Defects in canonical Wnt signalling, which is transduced intracellularly by β-catenin, have been associated with developmental disorders, degenerative diseases and cancers. Although a simple model describing Wnt-β-catenin signalling is widely used to introduce this pathway and has largely remained unchanged over the past 30 years, in this Review we discuss recent studies that have provided important new insights into the mechanisms of Wnt production, receptor activation and intracellular signalling that advance our understanding of the molecular mechanisms that underlie this important cell-cell communication system. In addition, we review the recent development of molecules capable of activating the Wnt-β-catenin pathway with selectivity in vitro and in vivo that is enabling new lines of study to pave the way for the development of Wnt therapies for the treatment of human diseases.

Novel CTNNB1 Gene Variants in Spanish CTNNB1 Syndrome Patients: Clinical and Psychological Manifestations

CTNNB1 Syndrome is a neurodevelopmental disorder caused by de novo pathogenic variants characterized by global cognitive impairment, microcephaly, speech and motor delay, abnormal muscle tone, ophthalmologic impairments, behaviour problems and autistic spectrum disorder (ASD) symptoms. The aim of this study is to carry out a thorough clinical and psychological characterization of Spanish CTNNB1 syndrome patients. We used standard clinical assessment instruments and an ad hoc questionnaire to measure motor functioning, neurodevelopmental milestones, sleep problems, daily life activities, behavioural problems, communication and speech impairments, eating disorders and autistic features in 25 participants with CTNNB1 syndrome (15 females, 10 males; mean age 7.1 ± 4.1). Main clinical manifestations reported were microcephaly, motor impairment, sight problems, sleep disturbances and sensorial problems. Attainment of developmental milestones indicated motoric, language and daily living skills to be generally delayed. All participants had adaptative skills below their chronological age, even though verbal individuals had better functioning compared to nonverbal. Regarding behaviour impairments, CTNNB1 syndrome patients scored significantly high at internalizing and externalizing behavioural problems. Additionally, about 60% presented symptoms of ASD. Our findings have important implications for the psychotherapeutic and clinical approaches of CTNNB1 syndrome patients. We show the importance of early stimulation, given that an early attainment of developmental milestones is related to a current better function of many clinical variables. Moreover, previous underrated symptoms such as sleep problems, impaired adaptative skills and high rates of behavioural symptoms should be taken into consideration due to the harmful impact that have on every day life.

Molecular landscape of clear cell renal cell carcinoma: targeting the Wnt/β-catenin signaling pathway

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal cell carcinoma and is characterized by a complex molecular landscape driven by genetic and epigenetic alternations. Among the crucial signaling pathways implicated in ccRCC, the Wnt/β-catenin pathway plays a significant role in tumor progression and prognosis. This review delves into the molecular basis of ccRCC, highlighting the genetic and epigenetic modifications that contribute to its pathogenesis. We explore the significance of the Wnt/β-catenin pathway, focusing on its role in disease development, particularly the nuclear transport of β-catenin and its activation and downstream effects. Furthermore, we examine the role of antagonist genes in regulating this pathway within the context of ccRCC, providing insights into potential therapeutic targets. Dysregulation of this pathway, which is characterized by abnormal activation and nuclear translocation of β-catenin, plays a significant role in promoting tumor growth and metastasis. We explore the intricate molecular aspects of ccRCC, with a particular emphasis on this topic, underscoring the role of the pathway and emphasizing the importance and relevance of antagonist genes. Understanding the intricate interplay between these molecular mechanisms is crucial for developing innovative strategies to improve ccRCC treatment and patient outcomes.

Advancements in the research of the structure, function, and disease-related roles of ARMC5

The armadillo repeat containing 5 (ARMC5) gene is part of a family of protein-coding genes that are rich in armadillo repeat sequences, are ubiquitously present in eukaryotes, and mediate interactions between proteins, playing roles in various cellular processes. Current research has demonstrated that reduced expression or absence of the ARMC5 gene in various tumor tissues can lead to uncontrolled cell proliferation, thereby inducing a range of diseases. The ARMC5 gene was initially extensively studied in the context of bilateral macronodular adrenocortical disease (BMAD), with harmful pathogenic variants in ARMC5 identified in approximately 50% of BMAD patients. With advancing research, scientists have discovered that ARMC5 pathogenic variants may also have potential effects on other diseases and could be associated with increased susceptibility to certain cancers. This review aims to present the latest research progress on how the ARMC5 gene plays its role in tumors. It outlines the basic structure of ARMC5 and the regions where it functions, as well as the diseases currently proven to be associated with ARMC5. Moreover, some evidence suggests its relation to embryonic development and the regulation of immune system activity. In conclusion, the ARMC5 gene is a crucial focal point in genetic and medical research. Understanding its function and regulation is of great importance for the development of new therapeutic strategies related to diseases associated with its pathogenic variants.

Plakoglobin does not participate in endothelial barrier stabilization mediated by cAMP

Critical for maintenance of endothelial barrier is the remodeling of the actin cytoskeleton and the precise control of junctional integrity. Plakoglobin (PG) is a structural and signaling protein involved in vascular permeability regulation together with key signaling molecules such as cAMP, Rho GTPases and actin-binding proteins. Here, we investigated the role of PG in cAMP-mediated endothelial barrier stabilization by establishing myocardial endothelial cells derived from wild type (WT) and PG knock-out (PG-KO) mice. Under basal conditions, TEER measurements showed increased barrier function of PG-KO, an effect associated with enhanced protein levels and junctional VE-cadherin and β-catenin accumulation. PG-KO cells also displayed more PECAM-1 and VE-PTP-phosphatase and less phosphorylated VE-cadherin, typically linked with modulation of junctional integrity. PG ablation neither changed the composition of VE-cadherin/β-catenin complex nor activities of Rac1 and RhoA but decreased the basal intracellular cAMP concentration. Remarkably, cAMP augmentation led to enhanced Rac1 activity and TEER in both cell lines, but the effect was less prominent in PG-KO. The tighter barrier in WT was paralleled with more VE-cadherin, β-catenin and cortactin, an actin-binding protein, towards junctions. Surprisingly, PG phosphorylation at Ser665 was not required for cAMP-mediated endothelial barrier integrity, which is different to cardiomyocyte and keratinocyte cell adhesion.

Decoding β-catenin associated protein-protein interactions: Emerging cancer therapeutic opportunities

The hyperactive Wnt/β-catenin signaling circuit has been proven to be closely related to the progression of various cancers, with β-catenin serving as a central regulator of pro-tumorigenic processes. Preclinical evidences strongly support β-catenin as a promising therapeutic target. However, it has long been considered "undruggable" due to challenges such as the lack of crystal structures for its N- and C-terminal domains, high mutation rates, and limited availability of inhibitors. Notably, the network of β-catenin-associated protein-protein interactions (PPIs) is vital in the progression of multiple diseases. These interactions form a cancer-specific network that participates in all phases of oncogenesis, from cell metastasis to immunosuppressive microenvironment formation. Thus, researches on these PPIs are essential for unraveling the molecular mechanisms behind tumors with aberrant β-catenin activation, as well as for developing new targeted therapies. In this review, we delve into how β-catenin's PPIs orchestrate cancer progression and highlight biological and clinical dilemmas, proposing frontier technologies and potential challenges in targeting β-catenin for cancer therapy.

Combinatorial Effects of 5-Fluorouracil and Menadione on Wnt/β-Catenin Pathway in Human Colorectal Cancer Cells

The incidence and mortality rates of colorectal cancer (CRC) are alarmingly high, and the scientific community is consistently engaged in developing newer therapeutic options for cancer cure or prevention. The fluoropyrimidine drug, 5-fluorouracil (5FU), remains the first line of treatment against CRC; nevertheless, relapses frequently occur since the cells gain resistance over time through various mechanisms. Studies have highlighted the significance of combinatorial treatment of a Wnt signaling inhibitor and 5FU as a better treatment strategy to overcome 5FU resistance. Small molecules that specifically target and disrupt β-catenin-TCF interaction, a crucial step of the Wnt signaling, are promising in CRC treatment. In this study, we investigated the synergistic cytotoxic activity of menadione with 5FU as the former has previously been shown to downregulate Wnt signaling in CRC cells. Docking and experimental results suggest that the drug combination interfered with key protein-protein interactions in the β-catenin-TCF complex, exerted synergistic anti-cancerous effects in CRC cells, and downregulated the expression of Wnt signaling proteins. Taken together, our data suggest that the simultaneous binding of 5FU and menadione to β-catenin can block Wnt signaling by disrupting β-catenin-TCF interaction and inhibit the proliferation of CRC cells.

Comprehensive analysis of the expression and prognostic value of ARMCs in pancreatic adenocarcinoma

BACKGROUND

Pancreatic adenocarcinoma (PAAD) has a very poor prognosis, and there are few treatments for PAAD. Therefore, it is important to find some biomarkers for the diagnosis and treatment of PAAD. Although some members of Armadillo repeat containing proteins (ARMCs) have been implicated in the development of certain cancers, their relationship with PAAD remains unknown. In this study, we aimed to explore the expression and prognostic value of ARMCs in PAAD.

METHODS

We used the The Cancer Genome Atlas (TCGA) database for survival analysis. Then, Gene Expression Profiling Interactive Analysis (GEPIA), the cBioPortal database, the Human Protein Atlas (HPA), Kaplan-Meier Plotter, LinkedOmics Database, Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG), Cytoscape and Timer were used to analyze the relationship between ARMCs and PAAD. In addition, we established a prognostic model of ARMCs for PAAD. Immunohistochemistry (IHC) was also performed. Then Image-J was used to analyze all images obtained from the experiment, and GraphPad-Prism (9.5.1) was used for statistical analysis to verify the expression of ARMCs in PAAD.

RESULTS

In the TCGA database, the expressions of ARMC1, 2, 3, 5, 6, 7, 8, 9 and 10 in PAAD tissues were significantly higher than those in normal tissues. And higher expressions of ARMC1 and 10 were associated with lower survival rate of PAAD patients. In addition, ARMC2, 5, 6, and 10 were positively associated with advanced stages of PAAD. ARMCs mutations occur in 11% of PAAD patients, and missense mutations and amplification of ARMCs account for most of them. In addition, ARMC5 and ARMC10 were independent prognostic factors in univariate and multivariate Cox regression analyses. Finally, through our confirmation experiment, it was found that the expression of ARMC1 and 10 in PAAD tissues was significantly increased compared with those in paracancer tissue.

CONCLUSION

This study suggests that ARMCs may be able to play important roles in PAAD, and they can act as biomarkers, providing valuable clues for the treatment and diagnosis of PAAD.

Development of novel osteoarthritis therapy by targeting AMPK-β-catenin-Runx2 signaling

Osteoarthritis (OA) is a debilitating chronic joint disease affecting large populations of patients, especially the elderly. The pathological mechanisms of OA are currently unknown. Multiple risk factors are involved in OA development. Among these risk factors, alterations of mechanical loading in the joint leading to changes in biological signaling pathways have been known as a key event in OA development. The importance of AMPK-β-catenin-Runx2 signaling in the initiation and progression of OA has been recognized in recent years. In this review, we discuss the recent progress in understanding the role of this signaling pathway and the underlying interaction mechanisms during OA development. We also discuss the drug development aiming to target this signaling pathway for OA treatment.

Pancancer analysis of the interactions between CTNNB1 and infiltrating immune cell populations

Recently, evidence has indicated that CTNNB1 is important in a variety of malignancies. However, how CTNNB1 interacts with immune cell infiltration remains to be further investigated. In this study, we focused on the correlations between CTNNB1 and tumorigenesis, tumor progression, mutation, phosphorylation, and prognosis via gene expression profiling interaction analysis; TIMER 2.0, cBioPortal, GTEx, CPTAC, and GEPIA2 database analyses; and R software. CTNNB1 mutations are most found in uterine endometrioid carcinoma and hepatocellular carcinoma. However, no CTNNB1 mutations were found to be associated with a poor prognosis. In addition, CTNNB1 DNA methylation levels were higher in normal tissues than in tumor tissues in cancer except for breast invasive carcinoma, which had higher methylation levels in tumor tissues. The phosphorylation level of the S675 and S191 sites of CTNNB1 was greater in the primary tumor tissues in the clear cell renal cell carcinoma, liver hepatocellular carcinoma, lung adenocarcinoma, pancreatic adenocarcinoma, and breast cancer datasets but not in the glioblastoma multiform dataset. As for, with respect to immune infiltration, CD8 + T-cell infiltration was negatively correlated with the expression of CTNNB1 in thymoma and uterine corpus endometrial carcinoma. The CTNNB1 level was found to be positively associated with the infiltration index of the corresponding fibroblasts in the TCGA tumors of colon adenocarcinoma, human papillomavirus-negative head and neck squamous cell carcinoma, mesothelioma, testicular germ cell tumor, and thymoma. We also identified the top CTNNB1-correlated genes in the TCGA projects and analyzed the expression correlation between CTNNB1 and selected target genes, including PPP4R2, RHOA, and SPRED1. Additionally, pathway enrichment suggested that NUMB is involved in the Wnt pathway. This study highlights the predictive role of CTNNB1 across cancers, suggesting that CTNNB1 might serve as a potential biomarker for the diagnosis and prognosis evaluation of various malignant tumors.

RESC14 and RESC8 cooperate to mediate RESC function and dynamics during trypanosome RNA editing

Mitochondrial transcripts in Trypanosoma brucei require extensive uridine insertion/deletion RNA editing to generate translatable open reading frames. The RNA editing substrate binding complex (RESC) serves as the scaffold that coordinates the protein-protein and protein-RNA interactions during editing. RESC broadly contains two modules termed the guide RNA binding complex (GRBC) and the RNA editing mediator complex (REMC), as well as organizer proteins. How the protein and RNA components of RESC dynamically interact to facilitate editing is not well understood. Here, we examine the roles of organizer proteins, RESC8 and RESC14, in facilitating RESC dynamics. High-throughput sequencing of editing intermediates reveals an overlapping RESC8 and RESC14 function during editing progression across multiple transcripts. Blue native PAGE analysis demonstrates that RESC14 is essential for incorporation of RESC8 into a large RNA-containing complex, while RESC8 is important in recruiting a smaller ribonucleoprotein complex (RNP) to this large complex. Proximity labeling shows that RESC14 is important for stable RESC protein-protein interactions, as well as RESC-RECC associations. Together, our data support a model in which RESC14 is necessary for assembly of editing competent RESC through recruitment of an RNP containing RESC8, GRBC and gRNA to REMC and mRNA.

Prognostic impact of tumor location and gene expression profile in sporadic desmoid tumor

PURPOSE

Prognostic biomarkers remain necessary in sporadic desmoid tumor (DT) because the clinical course is unpredictable. DT location along with gene expression between thoracic and abdominal wall locations was analyzed.

METHOD

Sporadic DT patients (GEIS Registry) diagnosed between 1982 and 2018 who underwent upfront surgery were enrolled retrospectively in this study. The primary endpoint was relapse-free survival (RFS). Additionally, the gene expression profile was analyzed in DT localized in the thoracic or abdominal wall, harboring the most frequent CTNNB1 T41A mutation.

RESULTS

From a total of 454 DT patients, 197 patients with sporadic DT were selected. The median age was 38.2 years (1.8-89.1) with a male/female distribution of 33.5/66.5. Most of them harbored the CTNNB1 T41A mutation (71.6 %), followed by S45F (17.8 %) and S45P (4.1 %). A significant worse median RFS was associated with males (p = 0.019), tumor size ≥ 6 cm (p = 0.001), extra-abdominal DT location (p < 0.001) and the presence of CTNNB1 S45F mutation (p = 0.013). In the multivariate analysis, extra-abdominal DT location, CTNNB1 S45F mutation and tumor size were independent prognostic biomarkers for worse RFS. DTs harboring the CTNNB1 T41A mutation showed overexpression of DUSP1, SOCS1, EGR1, FOS, LIF, MYC, SGK1, SLC2A3, and IER3, and underexpression of BMP4, PMS2, HOXA9, and WISP1 in thoracic versus abdominal wall locations.

CONCLUSION

Sporadic DT location exhibits a different prognosis in terms of RFS favoring the abdominal wall compared to extra-abdominal sites. A differential gene expression profile under the same CTNNB1 T41A mutation is observed in the abdominal wall versus the thoracic wall, mainly affecting the Wnt/β-catenin, TGFβ, IFN, and TNF pathways.

Boolean Modeling of Biological Network Applied to Protein-Protein Interaction Network of Autism Patients

Cellular molecules interact with one another in a structured manner, defining a regulatory network topology that describes cellular mechanisms. Genetic mutations alter these networks' pathways, generating complex disorders such as autism spectrum disorder (ASD). Boolean models have assisted in understanding biological system dynamics since Kauffman's 1969 discovery, and various analytical tools for regulatory networks have been developed. This study examined the protein-protein interaction network created in our previous publication of four ASD patients using the SPIDDOR R package, a Boolean model-based method. The aim is to examine how patients' genetic variations in INTS6L, USP9X, RSK4, FGF5, FLNA, SUMF1, and IDS affect mTOR and Wnt cell signaling convergence. The Boolean network analysis revealed abnormal activation levels of essential proteins such as β-catenin, MTORC1, RPS6, eIF4E, Cadherin, and SMAD. These proteins affect gene expression, translation, cell adhesion, shape, and migration. Patients 1 and 2 showed consistent patterns of increased β-catenin activity and decreased MTORC1, RPS6, and eIF4E activity. However, patient 2 had an independent decrease in Cadherin and SMAD activity due to the FLNA mutation. Patients 3 and 4 have an abnormal activation of the mTOR pathway, which includes the MTORC1, RPS6, and eIF4E genes. The shared mTOR pathway behavior in these patients is explained by a shared mutation in two closely related proteins (SUMF1 and IDS). Diverse activities in β-catenin, MTORC1, RPS6, eIF4E, Cadherin, and SMAD contributed to the reported phenotype in these individuals. Furthermore, it unveiled the potential therapeutic options that could be suggested to these individuals.

Transient, nano-scale, liquid-like molecular assemblies coming of age

This review examines the dynamic mechanisms underlying cellular signaling, communication, and adhesion via transient, nano-scale, liquid-like molecular assemblies on the plasma membrane (PM). Traditional views posit that stable, solid-like molecular complexes perform these functions. However, advanced imaging reveals that many signaling and scaffolding proteins only briefly reside in these molecular complexes and that micron-scale protein assemblies on the PM, including cell adhesion structures and synapses, are likely made of archipelagoes of nanoliquid protein islands. Borrowing the concept of liquid-liquid phase separation to form micron-scale biocondensates, we propose that these nano-scale oligomers and assemblies are enabled by multiple weak but specific molecular interactions often involving intrinsically disordered regions. The signals from individual nanoliquid signaling complexes would occur as pulses. Single-molecule imaging emerges as a crucial technique for characterizing these transient nanoliquid assemblies on the PM, suggesting a shift toward a model where the fluidity of interactions underpins signal regulation and integration.

Exploring the effect of 6-BIO and sulindac in modulation of Wnt/β-catenin signaling pathway in chronic phase of temporal lobe epilepsy

The prospective involvement of the Wnt/β-catenin signaling pathway in epilepsy, with the proposed therapeutic uses of its modulators, has been suggested; however, comprehensive knowledge in this regard is currently limited. Despite postulations about the pathway's significance and treatment potential, a systematic investigation is required to better understand its implications in chronic epilepsy. We investigated the role of key proteins like β-catenin, GSK-3β, and their modulators sulindac and 6-BIO, in Wnt/β-catenin pathway during chronic phase of temporal lobe epilepsy. We also evaluated the role of modulators in seizure score, seizure frequency and neurobehavioral parameters in temporal lobe epilepsy. We developed status epilepticus model using lithium-pilocarpine. The assessment of neurobehavioral parameters was done followed by histopathological examination and immunohistochemistry staining of hippocampus as well as RT-qPCR and western blotting to analyse gene and protein expression. In SE rats, seizure score and frequency were significantly high compared to control rats, with notable changes in neurobehavioral parameters and neuronal damage observed in hippocampus. Our study also revealed a substantial upregulation of the Wnt/β-catenin pathway in chronic epilepsy, as evidenced by gene and protein expression studies. Sulindac emerged as a potent modulator, reducing seizure score, frequency, neuronal damage, apoptosis, and downregulating the Wnt/β-catenin pathway when compared to 6-BIO. Our findings emphasize the potential of GSK-3β and β-catenin as promising drug targets for chronic temporal lobe epilepsy, offering valuable treatment options for chronic epilepsy. The promising outcomes with sulindac encourages further exploration in clinical trials to assess its therapeutic potential.

Computational investigations into structure and function impact of novel mutations identified in targeted exons from ovarian cancer cell lines

The lack of sensitive and specific biomarkers for ovarian cancer leads to late stage diagnosis of the disease in a majority of the cases. Mutation accumulation is the basis for cancer progression, thus identifying mutations is an important step in the disease diagnosis. In the present study, a comprehensive analysis of fifteen Next Generation Sequencing samples from thirteen ovarian cancer cell lines was carried out for the identification of new mutations. The study revealed eight clinically significant novel mutations in six ovarian cancer oncogenes, viz. SMARCA4, ARID1A, PPP2R1A, CTNNB1, DICER1 and PIK3CA. In-depth computational analysis revealed that the mutations affected the structure of the proteins in terms of stability, solvent accessible surface area and molecular dynamics. Moreover, the mutations were present in functionally significant domains of the proteins, thereby adversely affecting the protein functionality. PPI network for SMARCA4, CTNNB1, DICER1, PIK3CA, PPP2R1A and ARID1A showed that these genes were involved in certain significant pathways affecting various hallmarks of cancer. For further validation, in vitro studies were performed that revealed hypermutability of the CTNNB1 gene. Through this study we have identified some key mutations and have analysed their structural and functional impact. The study establishes some key mutations, which can be potentially explored as biomarker and drug target.

β-catenin inhibitors in cancer therapeutics: intricacies and way forward

β-catenin is an evolutionary conserved, quintessential, multifaceted protein that plays vital roles in cellular homeostasis, embryonic development, organogenesis, stem cell maintenance, cell proliferation, migration, differentiation, apoptosis, and pathogenesis of various human diseases including cancer. β-catenin manifests both signaling and adhesive features. It acts as a pivotal player in intracellular signaling as a component of versatile WNT signaling cascade involved in embryonic development, homeostasis as well as in carcinogenesis. It is also involved in Ca2+ dependent cell adhesion via interaction with E-cadherin at the adherens junctions. Aberrant β-catenin expression and its nuclear accumulation promote the transcription of various oncogenes including c-Myc and cyclinD1, thereby contributing to tumor initiation, development, and progression. β-catenin's expression is closely regulated at various levels including its stability, sub-cellular localization, as well as transcriptional activity. Understanding the molecular mechanisms of regulation of β-catenin and its atypical expression will provide researchers not only the novel insights into the pathogenesis and progression of cancer but also will help in deciphering new therapeutic avenues. In the present review, we have summarized the dual functions of β-catenin, its role in signaling, associated mutations as well as its role in carcinogenesis and tumor progression of various cancers. Additionally, we have discussed the challenges associated with targeting β-catenin molecule with the presently available drugs and suggested the possible way forward in designing new therapeutic alternatives against this oncogene.

Mechanisms Underlying Rare Inherited Pediatric Retinal Vascular Diseases: FEVR, Norrie Disease, Persistent Fetal Vascular Syndrome

Familial Exudative Vitreoretinopathy (FEVR), Norrie disease, and persistent fetal vascular syndrome (PFVS) are extremely rare retinopathies that are clinically distinct but are unified by abnormal retinal endothelial cell function, and subsequent irregular retinal vascular development and/or aberrant inner blood-retinal-barrier (iBRB) function. The early angiogenesis of the retina and its iBRB is a delicate process that is mediated by the canonical Norrin Wnt-signaling pathway in retinal endothelial cells. Pathogenic variants in genes that play key roles within this pathway, such as NDP, FZD4, TSPAN12, and LRP5, have been associated with the incidence of these retinal diseases. Recent efforts to further elucidate the etiology of these conditions have not only highlighted their multigenic nature but have also resulted in the discovery of pathological variants in additional genes such as CTNNB1, KIF11, and ZNF408, some of which operate outside of the Norrin Wnt-signaling pathway. Recent discoveries of FEVR-linked variants in two other Catenin genes (CTNND1, CTNNA1) and the Endoplasmic Reticulum Membrane Complex Subunit-1 gene (EMC1) suggest that we will continue to find additional genes that impact the neural retinal vasculature, especially in multi-syndromic conditions. The goal of this review is to briefly highlight the current understanding of the roles of their encoded proteins in retinal endothelial cells to understand the essential functional mechanisms that can be altered to cause these very rare pediatric retinal vascular diseases.

Solid pseudopapillary neoplasm: Report of a case of primary ovarian origin and review of the literature

Background

Solid pseudopapillary neoplasms (SPNs) are uncommon tumors of low malignancy with a generally favorable prognosis, mostly originating from the pancreas. To date, 12 cases of SPNs with a primary ovarian origin (SPN-Os) have been reported globally, and their detailed characteristics have not been fully elucidated.

Case description

We reported the 13th SPN-O case, which occurred in a 52-year-old woman with an 18.5 cm left ovarian mass. Four imaging methods, including ultrasound, computed tomography, magnetic resonance imaging and positron emission tomography, were utilized before surgery. An elevated level of serum cancer antigen 125 was detected and a total hysterectomy plus bilateral salpingo-oophorectomy was performed. Microscopic examination revealed a typical solid pseudopapillary structure. The tumor cells were stained focally for pan-cytokeratin, synaptophysin, CD99 and CD10, while β-catenin, vimentin and CD56 were diffusely expressed. The Ki-67 proliferation index was 3%, and immunohistochemical (IHC) staining for chromogranin-A, inhibin-a, and E-cadherin was negative. No evidence of recurrence or metastasis was observed by clinical and imaging data during a 5-month postoperative follow-up.

Conclusion

This is a report of an unusual case of a primary ovarian SPN with an up-to-date review of SPN-Os. A minimum combination of imaging methods and IHC stains was proposed for SPN-Os, which may prove beneficial in clinical practice.

Tissue tension permits β-catenin phosphorylation to drive mesoderm specification in human embryonic stem cells

The role of morphogenetic forces in cell fate specification is an area of intense interest. Our prior studies suggested that the development of high cell-cell tension in human embryonic stem cells (hESC) colonies permits the Src-mediated phosphorylation of junctional β-catenin that accelerates its release to potentiate Wnt-dependent signaling critical for initiating mesoderm specification. Using an ectopically expressed nonphosphorylatable mutant of β-catenin (Y654F), we now provide direct evidence that impeding tension-dependent Src-mediated β-catenin phosphorylation impedes the expression of Brachyury (T) and the epithelial-to-mesenchymal transition (EMT) necessary for mesoderm specification. Addition of exogenous Wnt3a or inhibiting GSK3β activity rescued mesoderm expression, emphasizing the importance of force dependent Wnt signaling in regulating mechanomorphogenesis. Our work provides a framework for understanding tension-dependent β-catenin/Wnt signaling in the self-organization of tissues during developmental processes including gastrulation.

Microcystin-LR accelerates follicular atresia in mice via JNK-mediated adherent junction damage of ovarian granulosa cells

Microcystin-LR (MC-LR), one of aquatic environmental contaminants with reproductive toxicity produced by cyanobacterial blooms, but its toxic effects and mechanisms on the ovary are not fully understood. Here, proteomic techniques and molecular biology experiments were performed to study the potential mechanism of MC-LR-caused ovarian toxicity. Results showed that protein expression profile of ovarian granulosa cells (KK-1) was changed by 17 μg/mL MC-LR exposure. Comparing with the control group, 118 upregulated proteins as well as 97 downregulated proteins were identified in MC-LR group. Function of differentially expressed proteins was found to be enriched in pathways related to adherent junction, such as cadherin binding, cell-cell junction, cell adhesion and focal adherens. Furthermore, in vitro experiments, MC-LR significantly downregulated the expression levels of proteins associated with adherent junction (β-catenin, N-cadherin, and α-catenin) as well as caused cytoskeletal disruption in KK-1 cells (P < 0.05), indicating that the adherent junction was damaged. Results of in vivo experiments have shown that after 14 days of acute MC-LR exposure (40 μg/kg), damaged adherent junction and an increased number of atretic follicles were observed in mouse ovaries. Moreover, MC-LR activated JNK, an upstream regulator of adherent junction proteins, in KK-1 cells and mouse ovarian tissues. In contrast, JNK inhibition alleviated MC-LR-induced adherent junction damage in vivo and in vitro, as well as the number of atretic follicles. Taken together, findings from the present study indicated that JNK is involved in MC-LR-induced granulosa cell adherent junction damage, which accelerated follicular atresia. Our study clarified a novel mechanism of MC-LR-caused ovarian toxicity, providing a theoretical foundation for protecting female reproductive health from environmental pollutants.

Mechanisms of mutant β-catenin in endometrial cancer progression

Endometrial carcinoma (EC) is the most diagnosed gynecological malignancy in Western countries. Both incidence and mortality rates of EC have steadily risen in recent years. Despite generally favorable prognoses for patients with the endometrioid type of EC, a subset of patients has been identified with decreased progression-free survival. Patients in this group are distinguished from other endometrioid EC patients by the presence of exon 3 hotspot mutations in CTNNB1, the gene encoding for the β-catenin protein. β-catenin is an evolutionarily conserved protein with critical functions in both adherens junctions and Wnt-signaling. The exact mechanism by which exon 3 CTNNB1 mutations drive EC progression is not well understood. Further, the potential contribution of mutant β-catenin to adherens junctions' integrity is not known. Additionally, the magnitude of worsened progression-free survival in patients with CTNNB1 mutations is context dependent, and therefore the importance of this subset of patients can be obscured by improper categorization. This review will examine the history and functions of β-catenin, how these functions may change and drive EC progression in CTNNB1 mutant patients, and the importance of this patient group in the broader context of the disease.

Genetic and clinical characteristics of 24 mainland Chinese patients with CTNNB1 loss-of-function variants

BACKGROUND

Neurodevelopmental disorder with spastic diplegia and visual defects (NEDSDV) is a rare autosomal dominant syndrome, which is caused by the heterozygous germline loss-of-function variants in CTNNB1.

METHODS

We evaluated the clinical and genetic findings of 24 previously undescribed Chinese patients affected by CTNNB1-related disorders and explored the possible ethnicity-related phenotypic variations.

RESULTS

Twenty-one loss-of-function variants were identified within these 24 NEDSDV patients, including 14 novel CTNNB1 variants and 7 recurrent ones. The prominent clinical manifestations in our cohort are developmental delay/intellectual disability (100%), motor delay (100%), speech impairment (100%), dystonia (87.5%) and microcephaly (69.6%). The common facial dysmorphisms were consistent with previous reports, including wide nasal bridge (58.3%), bulbous nose (45.8%), long philtrum (45.8%) and thin upper lip (45.8%). In addition, 19 patients (79.2%) in our cohort had mild visual defects, while one affected individual (4.2%) had familial exudative vitreoretinopathy. Notably, we discovered that 20 patients (83.3%) exhibited various behavioral abnormalities, which is described in Chinese patients for the first time.

CONCLUSION

We provided the largest known Chinese cohort with pathogenic CTNNB1 variants, which not only helps to expand the variant spectrum of CTNNB1 gene, but further delineates the typical phenotype of this disorder in Chinese population.

The Role of Pharmacotherapeutic Agents in Children with Desmoid Tumors

Desmoid tumors (DT) are rare fibroblastic, soft-tissue tumors that do not metastasize but can aggressively infiltrate tissues causing significant chronic discomfort and/or functional impairment. In the pediatric population, the incidence of DT is greatest during infancy and adolescence but can occur at any age. Dysregulated β-catenin, most commonly resulting from mutations in either CTNNB1 or germline APC (adenomatous polyposis coli) drives DT. Most cases are sporadic but some are associated with predisposition syndromes such as familial adenomatous polyposis (FAP). Historically, treatment has been surgery. However, the recurrence rate after surgery can be high. Various systemic cytotoxic chemotherapy regimens used in other soft-tissue sarcomas have been applied to DT with differing results. Given the chronic and rarely life-threatening nature of this disease and the potential short- and long-term toxicity of these regimens, especially in children, alternative non-cytotoxic interventions have been investigated. Molecularly targeted agents such as tyrosine kinase and gamma secretase inhibitors have shown activity against DT. Innovative local control therapies are being employed as alternatives to surgery and radiation. Periods of prolonged stability and spontaneous regression in the absence of therapy in some patients has prompted wider adoption of an upfront active surveillance approach in the appropriate setting. This review will briefly summarize the epidemiology, pathophysiology, and clinical presentation of DT in children, then focus on historical, current, and future pharmacotherapeutic management and finally, propose areas for future study.

Low to Intermediate (Borderline) Grade Breast Spindle Cell Lesions on Needle Biopsy: Diagnostic Approach and Clinical Management

Spindle cell proliferations of the breast are a heterogeneous group of lesions ranging from benign or reactive lesions to aggressive malignant neoplasms. Diagnosis on core biopsy can be particularly challenging as lesions displaying different lineages associated with variable outcomes share overlapping morphologies (scar vs. fibromatosis-like metaplastic carcinoma) whereas individual entities can exhibit a large variety of appearances (myofibroblastoma). In this review, lesions are grouped into lineage, when possible, including those showing fibroblastic/myofibroblastic differentiation, ranging from entities that require no additional management, such as scar and nodular fasciitis, to those with unpredictable clinical outcomes such as fibromatosis and solitary fibrous tumor or locally aggressive behavior such as dermatofibrosarcoma protuberans. The review of low-grade vascular lesions includes atypical vascular lesion and low-grade angiosarcoma. Also discussed are various adipocytic lesions ranging from lipoma to liposarcoma, and rare smooth muscle and neural entities more commonly encountered in locations outside the breast, such as leiomyoma, neurofibroma, schwannoma, or granular cell tumor. Optimal histological evaluation of these entities merges clinical and radiologic data with morphology and ancillary testing. We present our approach to immunohistochemical and other ancillary testing and highlight issues in pathology correlation with imaging. Recent updates in the management of breast spindle cell lesions are addressed. In a well-sampled lesion with radiographic concordance, the core biopsy diagnosis reliably guides management and we advocate the inclusion of management recommendations in the pathology report. Precise characterization using up to date guidelines is important to identify a subset of patients who may safely avoid unnecessary surgical procedures. A multidisciplinary approach with close collaboration with our clinical colleagues is emphasized.

Targeting fibrosis, mechanisms and cilinical trials

Fibrosis is characterized by the excessive extracellular matrix deposition due to dysregulated wound and connective tissue repair response. Multiple organs can develop fibrosis, including the liver, kidney, heart, and lung. Fibrosis such as liver cirrhosis, idiopathic pulmonary fibrosis, and cystic fibrosis caused substantial disease burden. Persistent abnormal activation of myofibroblasts mediated by various signals, such as transforming growth factor, platelet-derived growth factor, and fibroblast growh factor, has been recongized as a major event in the occurrence and progression of fibrosis. Although the mechanisms driving organ-specific fibrosis have not been fully elucidated, drugs targeting these identified aberrant signals have achieved potent anti-fibrotic efficacy in clinical trials. In this review, we briefly introduce the aetiology and epidemiology of several fibrosis diseases, including liver fibrosis, kidney fibrosis, cardiac fibrosis, and pulmonary fibrosis. Then, we summarise the abnormal cells (epithelial cells, endothelial cells, immune cells, and fibroblasts) and their interactions in fibrosis. In addition, we also focus on the aberrant signaling pathways and therapeutic targets that regulate myofibroblast activation, extracellular matrix cross-linking, metabolism, and inflammation in fibrosis. Finally, we discuss the anti-fibrotic drugs based on their targets and clinical trials. This review provides reference for further research on fibrosis mechanism, drug development, and clinical trials.

Biophysical Survey of Small-Molecule β-Catenin Inhibitors: A Cautionary Tale

The canonical Wingless-related integration site signaling pathway plays a critical role in human physiology, and its dysregulation can lead to an array of diseases. β-Catenin is a multifunctional protein within this pathway and an attractive yet challenging therapeutic target, most notably in oncology. This has stimulated the search for potent small-molecule inhibitors binding directly to the β-catenin surface to inhibit its protein–protein interactions and downstream signaling. Here, we provide an account of the claimed (and some putative) small-molecule ligands of β-catenin from the literature. Through in silico analysis, we show that most of these molecules contain promiscuous chemical substructures notorious for interfering with screening assays. Finally, and in line with this analysis, we demonstrate using orthogonal biophysical techniques that none of the examined small molecules bind at the surface of β-catenin. While shedding doubts on their reported mode of action, this study also reaffirms β-catenin as a prominent target in drug discovery.

CTNNB1 (β-CATENIN) VITREORETINOPATHY: IMAGING CHARACTERISTICS AND SURGICAL MANAGEMENT

PURPOSE

We report a patient with CTNNB1-associated vitreoretinopathy. We discuss imaging findings and surgical management.

METHODS

Case report.

RESULTS

An 18-month-old girl with microcephaly, failure to thrive, developmental delay, and chronic rhinitis presented with bilateral central and peripheral tractional retinal detachments and an anomalous retinal vasculature. She underwent multimodal imaging and genetic testing, and we discuss successful surgical management.

CONCLUSION

CTNNB1 mutations can cause a vision-threatening vitreoretinopathy. We recommend CTNNB1 to be considered as part of the workup of patients presenting with familial exudative vitreoretinopathy-like clinical findings, especially if there are systemic manifestations.

Berberine retarded the growth of gastric cancer xenograft tumors by targeting hepatocyte nuclear factor 4α

BACKGROUND

Gastric cancer is the third deadliest cancer in the world and ranks second in incidence and mortality of cancers in China. Despite advances in prevention, diagnosis, and therapy, the absolute number of cases is increasing every year due to aging and the growth of high-risk populations, and gastric cancer is still a leading cause of cancer-related death. Gastric cancer is a consequence of the complex interaction of microbial agents, with environmental and host factors, resulting in the dysregulation of multiple oncogenic and tumor-suppressing signaling pathways. Global efforts have been made to investigate in detail the genomic and epigenomic heterogeneity of this disease, resulting in the identification of new specific and sensitive predictive and prognostic biomarkers. Trastuzumab, a monoclonal antibody against the HER2 receptor, is approved in the first-line treatment of patients with HER2+ tumors, which accounts for 13%-23% of the gastric cancer population. Ramucirumab, a monoclonal antibody against VEGFR2, is currently recommended in patients progressing after first-line treatment. Several clinical trials have also tested novel agents for advanced gastric cancer but mostly with disappointing results, such as anti-EGFR and anti-MET monoclonal antibodies. Therefore, it is still of great significance to screen specific molecular targets for gastric cancer and drugs directed against the molecular targets.

AIM

To investigate the effect and mechanism of berberine against tumor growth in gastric cancer xenograft models and to explore the role of hepatocyte nuclear factor 4α (HNF4α)-WNT5a/β-catenin pathways played in the antitumor effects of berberine.

METHODS

MGC803 and SGC7901 subcutaneous xenograft models were established. The control group was intragastrically administrated with normal saline, and the berberine group was administrated intragastrically with 100 mg/kg/d berberine. The body weight of nude mice during the experiment was measured to assess whether berberine has any adverse reaction. The volume of subcutaneous tumors during this experiment was recorded to evaluate the inhibitory effect of berberine on the growth of MGC803 and SGC7901 subcutaneous transplantation tumors. Polymerase chain reaction assays were conducted to evaluate the alteration of transcriptional expression of HNF4α, WNT5a and β-catenin in tumor tissues and liver tissues from the MGC803 and SGC7901 xenograft models. Western blotting and IHC were performed to assess the protein expression of HNF4α, WNT5a and β-catenin in tumor tissues and liver tissues from the MGC803 and SGC7901 xenograft models.

RESULTS

In the both MGC803 and SGC7901 xenograft tumor models, berberine significantly reduced tumor volume and weight and thus retarded the growth rate of tumors. In the SGC7901 and MGC803 subcutaneously transplanted tumor models, berberine down-regulated the expression of HNF4α, WNT5a and β-catenin in tumor tissues from both transcription and protein levels. Besides, berberine also suppressed the protein expression of HNF4α, WNT5a and β-catenin in liver tissues.

CONCLUSION

Berberine retarded the growth of MGC803 and SGC7901 xenograft model tumors, and the mechanism behind these anti-growth effects might be the downregulation of the expression of HNF4α-WNT5a/β-catenin signaling pathways both in tumor tissues and liver tissues of the xenograft models.

LRH-1 (liver receptor homolog-1) derived affinity peptide ligand to inhibit interactions between β-catenin and LRH-1 in pancreatic cancer cells: from computational design to experimental validation

Poor prognosis, rapid progression and the lack of an effective treatment make pancreatic cancer one of the most lethal malignancies. Recent studies point to a role for liver receptor homolog-1 (LRH-1) in pathogenesis of pancreatic cancer and suggest prevention of the β-catenin/LRH-1 complex formation as a potential strategy for inhibition of the pancreas cancer cells progression. In the current investigation, we have followed a biomimetic strategy and designed an affinity peptide with sequence DEMEEPQQTE to inhibit formation of the β-catenin/LRH-1 complex. Quantitative real-time PCR experiments on the AsPC-1 pancreatic metastatic cells showed that the peptide has an inhibitory effect on the Wnt signaling proliferation line by reducing the expression levels of the CCND1, CCNE1, and MYC genes. Furthermore, the increased expression level of BAX gene showed that AsPC-1 cells were directed to the apoptosis pathway. At last, POU5F1, KLF4, and CD44 gene expression levels suggested that the peptide has an inhibitory effect on the stemness feature of the AsPC-1 cells. Here, we introduced a novel peptide inhibitor targeting an important protein-protein interaction, the β-catenin/LRH-1 complex, which may provide highly promising starting points for subsequent drug design. Communicated by Ramaswamy H. Sarma.

The Valuable Role of ARMC1 in Invasive Breast Cancer as a Novel Biomarker

Background

Invasive breast carcinoma (BRCA) is a common type of breast cancer with a high clinical incidence. Thus, it is significant to find effective biomarkers for BRCA diagnosis and treatment. Although some members of armadillo (ARM) repeat family of proteins are confirmed to be biomarkers in cancers, the role of armadillo repeat-containing 1 (ARMC1) in BRCA remains unknown.

Methods

We firstly analyzed the ARMC1 expression in normal breast tissues and BRCA samples and its association with overall survival by the public database. Next, the χ 2 test was used to evaluate the prognostic significance of ARMC1 expression in TCGA-BRCA patient samples. The ARMC1 mutations in BRCA were explored in the cBioportal database. Besides, the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were used to explore the biological functions of ARMC1 in BRCA. Finally, immunohistochemistry and immunofluorescence staining were performed to validate the ARMC1 expression in BRCA.

Results

ARMC1 expression in tumor samples was significantly higher than that in normal tissues, and higher expression of ARMC1 was related to lower survival. Moreover, the tumor stage and histology of BRCA patients were associated with ARMC1 expression. ARMC1 genetic mutations occurred in 32% of BRCA patients, and the amplification and high expression of ARMC1 accounted for most of them. Furthermore, functional enrichment analysis suggested that ARMC1 might be involved in the cell cycle in BRCA. Ultimately, increased ARMC1 expression was found in clinical breast carcinoma tissues by our confirmatory experiments.

Conclusions

ARMC1 may play a significant role in BRCA and act as a biomarker, which provides valuable clues for the treatment and diagnosis of BRCA.

Advances in targeting the WNT/β-catenin signaling pathway in cancer

WNT/β-catenin signaling orchestrates various physiological processes, including embryonic development, growth, tissue homeostasis, and regeneration. Abnormal WNT/β-catenin signaling is associated with various cancers and its inhibition has shown effective antitumor responses. In this review, we discuss the pathway, potential targets for the development of WNT/β-catenin inhibitors, available inhibitors, and their specific molecular interactions with the target proteins. We also discuss inhibitors that are in clinical trials and describe potential new avenues for therapeutically targeting the WNT/β-catenin pathway. Furthermore, we introduce emerging strategies, including artificial intelligence (AI)-assisted tools and technology-based actionable approaches, to translate WNT/β-catenin inhibitors to the clinic for cancer therapy.

Targeting the Wnt Signaling Pathway in Liver Fibrosis for Drug Options: An Update

Liver fibrosis is a life-threatening disease, with challenging morbidity and mortality for healthcare systems worldwide. It imparts an enormous economic burden to societies, making continuous research and informational updates about its pathogenesis and treatment crucial. This review's focus is on the current knowledge about the Wnt signaling pathway, serving as an important pathway in liver fibrosis development and activation of hepatic stellate cells (HSCs). Two types of Wnt pathways are distinguished, namely the ß-catenin-dependent canonical and non-canonical Ca2+ or planar cell polarity (PCP)-dependent pathway. The dynamic balance of physiologically healthy liver and hepatocytes is disturbed by repeated liver injuries. Activation of the ß-catenin Wnt pathway prevents the regeneration of hepatocytes by the replacement of extracellular matrix (ECM), leading to the appearance of scar tissue and the formation of regenerated nodular hepatocytes, lacking the original function of healthy hepatocytes. Therefore, liver function is reduced due to the severely advanced disease. Selective inhibition of ß-catenin inhibits inflammatory processes (since chemokines and pro-inflammatory cytokines are produced during Wnt activation), reduces growth of activated HSCs and reduces collagen synthesis and angiogenesis, thereby reducing the progression of liver fibrosis in vivo. While the canonical Wnt pathway is usually inactive in a physiologically healthy liver, it shows activity during cell regeneration or renewal and in certain pathophysiological conditions, such as liver diseases and cancer. Targeted blocking of some of the basic components of the Wnt pathway is a therapeutic approach. These include the frizzled transmembrane receptor (Fz) receptors using the secreted frizzled-related protein family (sFRP), Fz-coreceptors low-density LRP 5/6 through dickkopf-related protein 1 (DKK1) or niclosamide, glycogen kinase-3 beta (GSK-3β) using SB-216763, cyclic-AMP response element-binding protein (CBP) using PRI-724 and ICG-001, the lymphoid enhancer binding factor (LEF)/T cell-specific transcription factor (TCF) system as well as Wnt inhibitory factor 1 (WIF1) and miR-17-5p using pinostilbene hydrate (PSH). Significant progress has been made in inhibiting Wnt and thus stopping the progression of liver fibrosis by diminishing key components for its action. Comprehending the role of the Wnt signaling pathway in liver fibrosis may lead to discovery of novel targets in liver fibrosis therapeutic strategies' development.

Structural overview and perspectives of the nuclear receptors, a major family as the direct targets for small-molecule drugs

The nuclear receptors (NRs) are an evolutionarily related family of transcription factors, which share certain common structural characteristics and regulate the expressions of various genes by recognizing different response elements. NRs play important roles in cell differentiation, proliferation, survival and apoptosis, rendering them indispensable in many physiological activities including growth and metabolism. As a result, dysfunctions of NRs are closely related to a variety of diseases, such as diabetes, obesity, infertility, inflammation, the Alzheimer's disease, cardiovascular diseases, prostate and breast cancers. Meanwhile, small-molecule drugs directly targeting NRs have been widely used in the treatment of above diseases. Here we summarize recent progress in the structural biology studies of NR family proteins. Compared with the dozens of structures of isolated DNA-binding domains (DBDs) and the striking more than a thousand of structures of isolated ligand-binding domains (LBDs) accumulated in the Protein Data Bank (PDB) over thirty years, by now there are only a small number of multi-domain NR complex structures, which reveal the integration of different NR domains capable of the allosteric signal transduction, or the detailed interactions between NR and various coregulator proteins. On the other hand, the structural information about several orphan NRs is still totally unavailable, hindering the further understanding of their functions. The fast development of new technologies in structural biology will certainly help us gain more comprehensive information of NR structures, inspiring the discovery of novel NR-targeting drugs with a new binding site beyond the classic LBD pockets and/or a new mechanism of action.

Super-enhancer-driven lncRNA-DAW promotes liver cancer cell proliferation through activation of Wnt/β-catenin pathway

Aberrant expression of long non-coding RNAs (lncRNAs) has been reported in multiple cancers. However, the underlying mechanisms mediated by super-enhancers remain elusive. Here we sought to define the role of a novel lncRNA termed lncRNA-DAW in tumorigenesis. Our results revealed that lncRNA-DAW was driven by a liver-specific super-enhancer and transcriptionally activated by HNF4G, leading to frequent elevation in hepatocellular carcinoma (HCC) specimens. Ectopic expression of lncRNA-DAW promoted both in vivo and in vitro tumor growth. By using RNA sequencing, Wnt2 was screened out as a downstream effector of lncRNA-DAW. We next found that lncRNA-DAW physically interacted with EZH2, a negative regulator of Wnt2. This interplay subsequently potentiated CDK1-EZH2 interaction, leading to the phosphorylation and ubiquitination of EZH2. The lncRNA-DAW-mediated EZH2 degradation facilitated the de-repression of Wnt2 transcription, which eventually activated the Wnt/β-catenin pathway. Furthermore, we verified that Wnt2 potentiated in vitro and in vivo cancer cell growth by activating the Wnt/β-catenin pathway. Finally, Wnt2 amplification was confirmed as a common event in liver cancer, and the expression of lncRNA-DAW was positively correlated with Wnt2 in HCC specimens. Collectively, we are the first to identify lncRNA-DAW as a novel candidate oncogene in liver cancer, and this lncRNA may serve as a novel clinical diagnosis biomarker for liver cancer.

Wnt signaling in dental pulp homeostasis and dentin regeneration

OBJECTIVE

Wnt signaling is crucial in the physiological and pathological processes of dental pulp tissues. The present study described the effects of Wnt signaling in dental pulp homeostasis and regeneration.

DESIGN

Publications in Pubmed and Scopus database were searched, and a narrative review was performed. The roles of Wnt signaling in dental pulp tissue were reviewed and discussed.

RESULT

In vitro and in vivo evidence have confirmed the involvement of Wnt signaling in tooth development, dental pulp homeostasis, and physiological processes in dental pulp responses. Manipulating Wnt signaling components generates beneficial effects on pulp healing, dentin repair, and epigenetic regulation related to stemness maintenance, implying that Wnt signaling is a potential therapeutic target for future clinical dental applications. Additionally, an overview of the epigenetic control of dental pulp stem cells by Wnt signaling is provided.

CONCLUSION

This review provides basic knowledge on Wnt signaling and outlines its functions in dental pulp tissues, focusing on their potential as therapeutic treatments by targeting the Wnt signaling pathway.

An insight into crosstalk among multiple signaling pathways contributing to epileptogenesis

Despite the years of research, epilepsy remains uncontrolled in one-third of afflicted individuals and poses a health and economic burden on society. Currently available anti-epileptic drugs mainly target the excitatory-inhibitory imbalance despite targeting the underlying pathophysiology of the disease. Recent research focuses on understanding the pathophysiologic mechanisms that lead to seizure generation and on possible new treatment avenues for preventing epilepsy after a brain injury. Various signaling pathways, including the mechanistic target of rapamycin (mTOR) pathway, mitogen-activated protein kinase (MAP-ERK) pathway, JAK-STAT pathway, wnt/β-catenin signaling, cAMP pathway, and jun kinase pathway, have been suggested to play an essential role in this regard. Recent work suggests that the mTOR pathway intervenes epileptogenesis and proposes that mTOR inhibitors may have antiepileptogenic properties for epilepsy. In the same way, several animal studies have indicated the involvement of the Wnt signaling pathway in neurogenesis and neuronal death induced by seizures in different phases (acute and chronic) of seizure development. Various studies have also documented the activation of JAK-STAT signaling in epilepsy and cAMP involvement in epileptogenesis through CREB (cAMP response element-binding protein). Although studies are there, the mechanism for how components of these pathways mediate epileptogenesis requires further investigation. This review summarises the current role of various signaling pathways involved in epileptogenesis and the crosstalk among them. Furthermore, we will also discuss the mechanical base for the interaction between these pathways and how these interactions could be a new emerging promising target for future epilepsy therapies.

Metabolic Contributions of Wnt Signaling: More Than Controlling Flight

The canonical Wnt signaling pathway is ubiquitous throughout the body and influences a diverse array of physiological processes. Following the initial discovery of the Wnt signaling pathway during wing development in Drosophila melanogaster, it is now widely appreciated that active Wnt signaling in mammals is necessary for the development and growth of various tissues involved in whole-body metabolism, such as brain, liver, pancreas, muscle, and adipose. Moreover, elegant gain- and loss-of-function studies have dissected the tissue-specific roles of various downstream effector molecules in the regulation of energy homeostasis. This review attempts to highlight and summarize the contributions of the Wnt signaling pathway and its downstream effectors on whole-body metabolism and their influence on the development of metabolic diseases, such as diabetes and obesity. A better understanding of the Wnt signaling pathway in these tissues may aid in guiding the development of future therapeutics to treat metabolic diseases.

Reconstitution of the destruction complex defines roles of AXIN polymers and APC in β-catenin capture, phosphorylation, and ubiquitylation

The Wnt/β-catenin pathway is a highly conserved, frequently mutated developmental and cancer pathway. Its output is defined mainly by β-catenin's phosphorylation- and ubiquitylation-dependent proteasomal degradation, initiated by the multi-protein β-catenin destruction complex. The precise mechanisms underlying destruction complex function have remained unknown, largely because of the lack of suitable in vitro systems. Here we describe the in vitro reconstitution of an active human β-catenin destruction complex from purified components, recapitulating complex assembly, β-catenin modification, and degradation. We reveal that AXIN1 polymerization and APC promote β-catenin capture, phosphorylation, and ubiquitylation. APC facilitates β-catenin's flux through the complex by limiting ubiquitylation processivity and directly interacts with the SCFβ-TrCP E3 ligase complex in a β-TrCP-dependent manner. Oncogenic APC truncation variants, although part of the complex, are functionally impaired. Nonetheless, even the most severely truncated APC variant promotes β-catenin recruitment. These findings exemplify the power of biochemical reconstitution to interrogate the molecular mechanisms of Wnt/β-catenin signaling.

Membrane Localization of β-Catenin in Prostate Cancer PC3 Cells Treated with Teucrium persicum Boiss. Extract

Teucrium persicum Boiss. is an Iranian endemic plant which belongs to the Lamiaceae family and has been used to relieve pains in traditional Iranian medicine. We have previously found that treatment of prostate cancer PC3 cells with Teucrium persicum extract leads to the formation of small populations of epithelial cells. β-Catenin is a component of cell adherens junctions in epithelial cells and therefore, in this study, we have investigated the effect of Teucrium persicum extract on expression, cellular localization, and transcriptional activity of β-Catenin protein in PC-3 cells. Indirect immunofluorescence microscopy results showed that the cells treated with T. persicum extract had higher levels of β-Catenin protein at the cell membrane. Western blotting experiments produced consistent results. Gene expression studies by using a few β-Catenin-target genes including c-MYC, CYCLIN D1, and a reporter Luciferase gene under the control of several β-Catenin/TCF binding elements showed that treatment of PC3 cells with the methanolic extract of T. persicum decreases the transcriptional activities of β-Catenin. The results of this study provide further support for the anticancer properties of T. persicum. Definitely, more detailed molecular investigations are needed to find the mechanism(s) behind these effects. Highlightsβ-Catenin protein is a main component of Wnt signaling pathway and adherens junction.Activation of Wnt signaling pathway affects translocation of β-Catenin.Teucrium persicum extract induces β-Catenin localization at cell membrane.Teucrium persicum affects the transcriptional activity of β-Catenin.It stabilizes E-cadherin/β-Catenin protein complex and adherens junction.

Advanced glycation end products induce endothelial hyperpermeability via β-catenin phosphorylation and subsequent up-regulation of ADAM10

Endothelial hyperpermeability is the initial event in the development of diabetic microvascular complications, and advanced glycation end products (AGEs) are suggested to cause much of the endothelial hyperpermeability associated with diabetes mellitus, but the molecular mechanism remains to be characterized. β-catenin reportedly plays dual functions in maintaining normal endothelial permeability by serving both as an adhesive component and a signal transduction component. Here, we found that AGEs induced the phosphorylation of β-catenin at residues Y654 and Y142 and the endothelial hyperpermeability was reversed when the two residues were blocked. In mechanism, phosphorylation of Y654 was blocked by Src inactivation, whereas phosphorylation of Y142 was reduced by a focal adhesion kinase inhibitor. β-catenin Y654 phosphorylation induced by AGEs facilitated the dissociation of vascular endothelial (VE)-cadherin/β-catenin and the impairment of adherens junctions (AJs), whereas β-catenin Y142 phosphorylation favoured the dissociation of β-catenin and α-catenin. Further investigation revealed that β-catenin Y142 phosphorylation was required for AGEs-mediated β-catenin nuclear translocation, and this nuclear-located β-catenin subsequently activated the TCF/LEF pathway. This pathway promotes the transcription of the Wnt target, ADAM10 (a disintegrin and metalloprotease 10), which mediates VE-cadherin shedding and leads to further impairment of AJs. In summary, our study showed the role of β-catenin Y654 and Y142 phosphorylation in AGEs-mediated endothelial hyperpermeability through VE-cadherin/β-catenin/α-catenin dissociation and up-regulation of ADAM10, thereby advancing our understanding of the underlying mechanisms of AGEs-induced microvascular hyperpermeability.

Spindle cell lesions of the breast: a diagnostic approach

Spindle cell lesions of the breast comprise a heterogeneous group of lesions, ranging from reactive and benign processes to aggressive malignant tumours. Despite their rarity, they attract the attention of breast pathologists due to their overlapping morphological features and diagnostic challenges, particularly on core needle biopsy (CNB) specimens. Pathologists should recognise the wide range of differential diagnoses and be familiar with the diverse morphological appearances of these lesions to make an accurate diagnosis and to suggest proper management of the patients. Clinical history, immunohistochemistry, and molecular assays are helpful in making a correct diagnosis in morphologically challenging cases. In this review, we present our approach for the diagnosis of breast spindle cell lesions, highlighting the main features of each entity and the potential pitfalls, particularly on CNB. Breast spindle cell lesions are generally classified into two main categories: bland-appearing and malignant-appearing lesions. Each category includes a distinct list of differential diagnoses and a panel of immunohistochemical markers. In bland-appearing lesions, it is important to distinguish fibromatosis-like spindle cell metaplastic breast carcinoma from other benign entities and to distinguish fibromatosis from scar tissue. The malignant-appearing category includes spindle cell metaplastic carcinoma, stroma rich malignant phyllodes tumour, other primary and metastatic malignant spindle cell tumours of the breast, including angiosarcoma and melanoma, and benign mimics such as florid granulation tissue and nodular fasciitis.

Parallel and Sequential Pathways of Molecular Recognition of a Tandem-Repeat Protein and Its Intrinsically Disordered Binding Partner

The Wnt signalling pathway plays an important role in cell proliferation, differentiation, and fate decisions in embryonic development and the maintenance of adult tissues. The twelve armadillo (ARM) repeat-containing protein β-catenin acts as the signal transducer in this pathway. Here, we investigated the interaction between β-catenin and the intrinsically disordered transcription factor TCF7L2, comprising a very long nanomolar-affinity interface of approximately 4800 Å2 that spans ten of the twelve ARM repeats of β-catenin. First, a fluorescence reporter system for the interaction was engineered and used to determine the kinetic rate constants for the association and dissociation. The association kinetics of TCF7L2 and β-catenin were monophasic and rapid (7.3 ± 0.1 × 107 M-1·s-1), whereas dissociation was biphasic and slow (5.7 ± 0.4 × 10-4 s-1, 15.2 ± 2.8 × 10-4 s-1). This reporter system was then combined with site-directed mutagenesis to investigate the striking variability in the conformation adopted by TCF7L2 in the three different crystal structures of the TCF7L2-β-catenin complex. We found that the mutation had very little effect on the association kinetics, indicating that most interactions form after the rate-limiting barrier for association. Mutations of the N- and C-terminal subdomains of TCF7L2 that adopt relatively fixed conformations in the crystal structures had large effects on the dissociation kinetics, whereas the mutation of the labile sub-domain connecting them had negligible effect. These results point to a two-site avidity mechanism of binding with the linker region forming a "fuzzy" complex involving transient contacts that are not site-specific. Strikingly, the two mutations in the N-terminal subdomain that had the largest effects on the dissociation kinetics showed two additional phases, indicating partial flux through an alternative dissociation pathway that is inaccessible to the wild type. The results presented here provide insights into the kinetics of the molecular recognition of a long intrinsically disordered region with an elongated repeat-protein surface, a process found to involve parallel routes with sequential steps in each.

Mitofusin-2 stabilizes adherens junctions and suppresses endothelial inflammation via modulation of β-catenin signaling

Endothelial barrier integrity is ensured by the stability of the adherens junction (AJ) complexes comprised of vascular endothelial (VE)-cadherin as well as accessory proteins such as β-catenin and p120-catenin. Disruption of the endothelial barrier due to disassembly of AJs results in tissue edema and the influx of inflammatory cells. Using three-dimensional structured illumination microscopy, we observe that the mitochondrial protein Mitofusin-2 (Mfn2) co-localizes at the plasma membrane with VE-cadherin and β-catenin in endothelial cells during homeostasis. Upon inflammatory stimulation, Mfn2 is sulfenylated, the Mfn2/β-catenin complex disassociates from the AJs and Mfn2 accumulates in the nucleus where Mfn2 negatively regulates the transcriptional activity of β-catenin. Endothelial-specific deletion of Mfn2 results in inflammatory activation, indicating an anti-inflammatory role of Mfn2 in vivo. Our results suggest that Mfn2 acts in a non-canonical manner to suppress the inflammatory response by stabilizing cell-cell adherens junctions and by binding to the transcriptional activator β-catenin.

Getting a Grip on the Undrugged: Targeting β-Catenin with Fragment-Based Methods

Aberrant WNT pathway activation, leading to nuclear accumulation of β-catenin, is a key oncogenic driver event. Mutations in the tumor suppressor gene APC lead to impaired proteasomal degradation of β-catenin and subsequent nuclear translocation. Restoring cellular degradation of β-catenin represents a potential therapeutic strategy. Here, we report the fragment-based discovery of a small molecule binder to β-catenin, including the structural elucidation of the binding mode by X-ray crystallography. The difficulty in drugging β-catenin was confirmed as the primary screening campaigns identified only few and very weak hits. Iterative virtual and NMR screening techniques were required to discover a compound with sufficient potency to be able to obtain an X-ray co-crystal structure. The binding site is located between armadillo repeats two and three, adjacent to the BCL9 and TCF4 binding sites. Genetic studies show that it is unlikely to be useful for the development of protein-protein interaction inhibitors but structural information and established assays provide a solid basis for a prospective optimization towards β-catenin proteolysis targeting chimeras (PROTACs) as alternative modality.

Sec62 promotes stemness and chemoresistance of human colorectal cancer through activating Wnt/β-catenin pathway

BACKGROUND

Cancer stem cell (CSC)-related chemoresistance leads to poor outcome of the patients with colorectal cancer (CRC). In this study, we identified the chemoresistance-relevant molecules and decipher the involved mechanisms to provide potential therapeutic target for CRC. We focused on Sec62, a novel target with significantly increased expression in chemoresistant CRC tissues, and further investigated its role in the progression of CRC.

METHODS

Through analyzing the differentially-expressed genes between chemoresistant and chemosensitive CRCs, we selected Sec62 as a novel chemoresistance-related target in CRC. The expression and clinical significance of Sec62 were determined by immunoblotting and immunohistochemistry in tissues and cell lines of CRC. The roles of Sec62 in drug resistance, stemness and tumorigenesis were evaluated in vitro and in vivo using functional experiments. GST pull-down, western blot, coimmunoprecipitation and Me-RIP assays were performed to further explore the downstream molecular mechanisms.

RESULTS

Sec62 upregulation was associated with the chemoresistance of CRC and poor outcome of CRC patients. Depletion of Sec62 sensitized CRC cells to chemotherapeutic drugs. Sec62 promoted the stemness of CRC cells through activating Wnt/β-catenin signaling. Mechanistically, Sec62 bound to β-catenin and inhibited the degradation of β-catenin. Sec62 competitively disrupted the interaction between β-catenin and APC to inhibit the β-catenin destruction complex assembly. Moreover, Sec62 expression was upregulated by the m6A-mediated stabilization of Sec62 mRNA.

CONCLUSIONS

Sec62 upregulated by the METTL3-mediated m6A modification promotes the stemness and chemoresistance of CRC by binding to β-catenin and enhancing Wnt signalling. Thus, m6A modification-Sec62-β-catenin molecular axis might act as therapeutic targets in improving treatment of CRC.

Mutations of Intrinsically Disordered Protein Regions Can Drive Cancer but Lack Therapeutic Strategies

Many proteins contain intrinsically disordered regions (IDRs) which carry out important functions without relying on a single well-defined conformation. IDRs are increasingly recognized as critical elements of regulatory networks and have been also associated with cancer. However, it is unknown whether mutations targeting IDRs represent a distinct class of driver events associated with specific molecular and system-level properties, cancer types and treatment options. Here, we used an integrative computational approach to explore the direct role of intrinsically disordered protein regions driving cancer. We showed that around 20% of cancer drivers are primarily targeted through a disordered region. These IDRs can function in multiple ways which are distinct from the functional mechanisms of ordered drivers. Disordered drivers play a central role in context-dependent interaction networks and are enriched in specific biological processes such as transcription, gene expression regulation and protein degradation. Furthermore, their modulation represents an alternative mechanism for the emergence of all known cancer hallmarks. Importantly, in certain cancer patients, mutations of disordered drivers represent key driving events. However, treatment options for such patients are currently severely limited. The presented study highlights a largely overlooked class of cancer drivers associated with specific cancer types that need novel therapeutic options.

Direct interaction of β-catenin with nuclear ESM1 supports stemness of metastatic prostate cancer

Wnt/β-catenin signaling is frequently activated in advanced prostate cancer and contributes to therapy resistance and metastasis. However, activating mutations in the Wnt/β-catenin pathway are not common in prostate cancer, suggesting alternative regulations may exist. Here, we report that the expression of endothelial cell-specific molecule 1 (ESM1), a secretory proteoglycan, is positively associated with prostate cancer stemness and progression by promoting Wnt/β-catenin signaling. Elevated ESM1 expression correlates with poor overall survival and metastasis. Accumulation of nuclear ESM1, instead of cytosolic or secretory ESM1, supports prostate cancer stemness by interacting with the ARM domain of β-catenin to stabilize β-catenin-TCF4 complex and facilitate the transactivation of Wnt/β-catenin signaling targets. Accordingly, activated β-catenin in turn mediates the nuclear entry of ESM1. Our results establish the significance of mislocalized ESM1 in driving metastasis in prostate cancer by coordinating the Wnt/β-catenin pathway, with implications for its potential use as a diagnostic or prognostic biomarker and as a candidate therapeutic target in prostate cancer.