The role of Pygo2 for Wnt/ß-catenin signaling activity during intestinal tumor initiation and progression

EFNA4 deletion suppresses the migration, invasion, stemness, and angiogenesis of gastric cancer cells through the inactivation of Pygo2/Wnt signaling

Gastric cancer represents an aggressive malignancy and a leading contributor to cancer death. Ephrin-A4 (EFNA4) has been proposed to be related to the immune microenvironment and prognosis of gastric cancer. This study was undertaken to discuss the participation and mechanism of EFNA4 in the development of gastric cancer. RT-qPCR and western blot examined EFNA4 and Pygopus2 (Pygo2) expression in gastric cancer cells. After transfection of EFNA4 interference plasmids or co-transfection of EFNA4 interference plasmids and Pygo2 overexpression plasmids, cell proliferation was detected by the CCK-8 method and EDU staining. Wound healing, Transwell, TUNEL, and endothelial cell tube formation assays detected cell migration, invasion, apoptosis, and angiogenesis, respectively. Western blot examined the expression of metastasis-, apoptosis-, angiogenesis-, and Wnt signaling-associated proteins. Cell stemness was estimated by the sphere formation assay, RT-qPCR, and western blot. Through the experimental data, it was noticed that EFNA4 expression was increased in gastric cancer cells. Knockdown of EFNA4 suppressed the proliferation, migration, invasion, angiogenesis as well as stemness while aggravating the apoptosis of gastric cancer cells. Also, EFNA4 depletion reduced Pygo2 protein expression and then inactivated Wnt/β-catenin signaling. Further elevation of Pygo2 reversed the impacts of EFNA4 silencing on Wnt/β-catenin signaling, cell proliferation, apoptosis, migration, invasion, angiogenesis as well as stemness in gastric cancer. Accordingly, the knockdown of EFNA4 might downregulate Pygo2 and inactivate Wnt/β-catenin signaling to exert protective effects against gastric cancer.

PYGO2 as a novel prognostic biomarker and its correlation with immune infiltrates in liver cancer

OBJECTIVE

The PYGO2 gene plays a significant role in various cancers. However, its prognostic significance and involvement in immune infiltration in liver cancer remain unclear. This study aimed to comprehensively evaluate PYGO2 expression and its associations with prognosis and clinicopathological features in liver cancer.

METHODS

Data from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases were analyzed. Functional enrichment analysis and immune cell infiltration assessments were performed to explore potential pathogenic mechanisms.

RESULTS

PYGO2 was highly expressed in multiple cancer types, including bladder urothelial carcinoma, breast invasive carcinoma, cholangiocarcinoma, diffuse large B-cell lymphoma, and liver cancer. Analysis of 50 paired liver cancer tissues from TCGA revealed significant upregulation of PYGO2 expression. Moreover, high PYGO2 expression was significantly associated with pathological T stage, overall pathological stage, tumor status, and race. Kaplan-Meier survival analysis showed that low PYGO2 expression correlated with improved overall survival (OS), disease-specific survival (DSS), and progression-free interval (PFI) in liver cancer patients. Functional enrichment analysis identified several enriched pathways, including the reactive oxygen species signaling pathway, MYC targets, interferon-alpha response, immune response regulation signaling pathway, and leukocyte migration. Additionally, PYGO2 overexpression was associated with lower proportions of cytotoxic cells, dendritic cells, immature dendritic cells, mast cells, neutrophils, plasmacytoid dendritic cell-like cells, Th17 cells, and regulatory T cells, but a higher proportion of Th2 cells. Furthermore, the high PYGO2 expression group exhibited increased immune checkpoint gene expression, particularly PDCD1.

CONCLUSION

PYGO2 is a promising prognostic biomarker for liver cancer, given its strong associations with clinicopathological features, survival outcomes, and immune-related characteristics.

PYGO2 promotes resistance to chemotherapy via reducing apoptosis and G2/M cell cycle arrest in esophageal carcinoma cells

5-FU is a widely used chemotherapy drug for esophageal carcinomas, but therapy failure has been observed in 5-FU-resistant patients. Overcoming this resistance is a significant challenge in cancer treatment, requiring identifying and targeting important resistance mechanisms. PYGO2 expression is crucial in developing resistance to various chemotherapy drugs. In this study, we aimed to investigate the impact of PYGO2 overexpression on the sensitivity of YM-1 and KYSE-30 esophageal carcinoma cells against 5-FU. To do this, we compared cell viability, cell cycle arrest, apoptosis rate, and mRNA expressions of various apoptosis-related genes between pcDNA3-PYGO2 transfected and untransfected KYSE-30 and YM-1 esophageal carcinoma cells following treatment with 5-FU. We showed that PYGO2 expression reduces 5-FU sensitivity in YM-1 and KYSE-30 cells. PYGO2-overexpressing cells treated with 5-FU have exhibited a noteworthy reduction in both early and late apoptotic cells compared to controls. Furthermore, a significant decrease in the Bax/Bcl2 ratio and P53 gene expression was observed. 5-FU induces G2/M cell cycle arrest in YM-1 and KYSE-30 cells. However, PYGO2 overexpression impeded G2/M cell cycle arrest in 5-FU-treated cells, thereby suppressing the toxicity of 5-FU. PYGO2 may mediate its apoptotic effect by regulating cell cycle regulatory proteins, specifically cyclin D1 and p21. These results highlight PYGO2's capacity to alter how esophageal cancer cells respond to 5-FU therapy, emphasizing its importance as a potential focal point for treatment strategies.

Histopathological Evaluation of PYGO2 Expression in Esophageal Squamous Cell Carcinoma

Background & Objective

Esophageal squamous cell carcinoma (ESCC) is one of the world's deadliest cancer diseases. Deregulation of developmental signaling pathways such as Wnt/β-catenin is frequently implicated in a wide range of human cancers. The present study was designed to analyze the expression of the Pygopus2 (PYGO2) protein, the main co-activator of the Wnt/β-catenin signaling pathway, in ESCC tissues and evaluate its probable correlation with clinicopathological features of patients.

Methods

In this study, PYGO2 protein expression was assessed in tumors and margin normal tissues from 50 ESCC patients using immunohistochemical analysis, and its clinicopathological relevance in the patients was evaluated.

Results

A significant PYGO2 overexpression was observed in %32 of the tumor cells. Interestingly, PYGO2 expression was significantly correlated with the depth of tumor invasion (P= 0.021).

Conclusion

PYGO2 protein may be highly expressed in ESCC in correlation with the invasiveness of the disease. Therefore, it may be used as a biomarker for diagnosis of invasive ESCC and a putative therapeutic target to inhibit ESCC invasiveness.

PYGO2 increases proliferation and migration capacities through critical signaling pathways in esophageal squamous cell carcinoma

Esophageal cancer, an increasingly prevalent malignancy, is a major concern for global health. The development of esophageal squamous cell carcinoma (ESCC) involves various genetic abnormalities that affect key cell signaling pathways, including Wnt, Hh, Apoptosis, MAPK, EGFR, AKT, Notch, and EMT. Additionally, this malignancy involves some changes in the expression of long noncoding RNAs (LncRNAs). The present study examines the relationship between PYGO2 gene expression and the activity of cell signaling pathways in KYSE-30 and YM-1ESCC cell lines. To this end, several cellular and molecular tests were performed, including cell migration, cell cycle, and apoptosis. Also, expression levels of CD133 and CD44 markers, real-time PCR, and western blot were analyzed after inducing PYGO2 protein expression in the cells. Overexpression of the PYGO2 protein resulted in the upregulation of Wnt pathway-related genes, leading to enhanced cell migration and proliferation and reduced apoptosis in both cell lines. Furthermore, PYGO2 gene expression induction analysis showed the correlation of several involved genes in Wnt, Hh, Apoptosis, MAPK, EGFR, AKT, and EMT pathways with various LncRNAs.

Pygo2 activates BRPF1 via Pygo2-H3K4me2/3 interaction to maintain malignant progression in colon cancer

Epigenetic alterations have essential roles during colon adenocarcinoma (COAD) progression. As the coactivator of Wnt/b-catenin signaling, Pygopus 2 (Pygo2) binds H3K4me2/3 and participate in chromatin remodeling in multiple cancers. However, It remains unclear whether the Pygo2-H3K4me2/3 association has significance in COAD. We aimed to elucidate the roles of Pygo2 in COAD. Functionally, Pygo2 inhibition attenuated cell proliferation, self-renewal capacities in vitro. Pygo2 overexpression enhanced in vivo tumor growth. Besides, Pygo2 overexpression could also enhance cell migration ability and in vivo distal metastasis. Mechanistically, Pygo2 correlates positively with BRPF1 expressions, one epigenetic reader of histone acetylation. The luciferase reporter assay and Chromatin Immunoprecipitation (ChIP)-qPCR assay were used to find that Pygo2 coordinated with H3K4me2/3 modifications to activate BRPF1 transcriptions via binding to the promoter. Both Pygo2 and BRPF1 expressed highly in tumors and Pygo2 relied on BRPF1 to accelerate COAD progression, including cell proliferation rate, migration abilities, stemness features and in vivo tumor growth. Targeting BPRF1 (GSK5959) is effective to suppress in vitro growth of Pygo2high cell lines, and has mild effect on Pygo2low cells. The subcutaneous tumor model further demonstrated that GSK5959 could effectively suppress the in vivo growth of Pygo2high COAD, but not the Pygo2low subtype. Collectively, our study represented Pygo2/BRPF1 as an epigenetic vulnerability for COAD treatment with predictive significance.

Targeting the chromatin effector Pygo2 promotes cytotoxic T cell responses and overcomes immunotherapy resistance in prostate cancer

The noninflamed microenvironment in prostate cancer represents a barrier to immunotherapy. Genetic alterations underlying cancer cell-intrinsic oncogenic signaling are increasingly appreciated for their role in shaping the immune landscape. Recently, we identified Pygopus 2 (PYGO2) as the driver oncogene for the amplicon at 1q21.3 in prostate cancer. Here, using transgenic mouse models of metastatic prostate adenocarcinoma, we found that Pygo2 deletion decelerated tumor progression, diminished metastases, and extended survival. Pygo2 loss augmented the activation and infiltration of cytotoxic T lymphocytes (CTLs) and sensitized tumor cells to T cell killing. Mechanistically, Pygo2 orchestrated a p53/Sp1/Kit/Ido1 signaling network to foster a microenvironment hostile to CTLs. Genetic or pharmacological inhibition of Pygo2 enhanced the antitumor efficacy of immunotherapies using immune checkpoint blockade (ICB), adoptive cell transfer, or agents inhibiting myeloid-derived suppressor cells. In human prostate cancer samples, Pygo2 expression was inversely correlated with the infiltration of CD8+ T cells. Analysis of the ICB clinical data showed association between high PYGO2 level and worse outcome. Together, our results highlight a potential path to improve immunotherapy using Pygo2-targeted therapy for advanced prostate cancer.

Chiral Graphene Quantum Dots Enhanced Drug Loading into Exosomes

As nanoscale extracellular vesicles secreted by cells, exosomes have enormous potential as safe and effective vehicles to deliver drugs into lesion locations. Despite promising advances with exosome-based drug delivery systems, there are still challenges to drug loading into exosome, which hinder the clinical applications of exosomes. Herein, we report an exogenous drug-agnostic chiral graphene quantum dots (GQDs) exosome-loading platform, based on chirality matching with the exosome lipid bilayer. Both hydrophobic and hydrophilic chemical and biological drugs can be functionalized or adsorbed onto GQDs by π-π stacking and van der Waals interactions. By tuning the ligands and GQD size to optimize its chirality, we demonstrate drug loading efficiency of 66.3% and 64.1% for Doxorubicin and siRNA, which is significantly higher than other reported exosome loading techniques.

Repulsion and attraction in searching: A hybrid algorithm based on gravitational kernel and vital few for cancer driver gene prediction

By taking a new perspective to combine a machine learning method with an evolutionary algorithm, a new hybrid algorithm is developed to predict cancer driver genes. Firstly, inspired by the search strategy with the capability of global search in evolutionary algorithms, a gravitational kernel is proposed to act on the full range of gene features. Constructed by fusing PPI and mutation features, the gravitational kernel is capable to produce repulsion effects. The candidate genes with greater mutation effects and PPI have higher similarity scores. According to repulsion, the similarity score of these promising genes is larger than ordinary genes, which is beneficial to search for these promising genes. Secondly, inspired by the idea of elite populations related to evolutionary algorithms, the concept of vital few is proposed. Targeted at a local scale, it acts on the candidate genes associated with vital few genes. Under attraction effect, these vital few driver genes attract those with similar mutational effects to them, which leads to greater similarity scores. Lastly, the model and parameters are optimized by using an evolutionary algorithm, so as to obtain the optimal model and parameters for cancer driver gene prediction. Herein, a comparison is performed with six other advanced methods of cancer driver gene prediction. According to the experimental results, the method proposed in this study outperforms these six state-of-the-art algorithms on the pan-oncogene dataset.

A diagnostic and prognostic value of blood-based circulating long non-coding RNAs in Thyroid, Pancreatic and Ovarian Cancer

Several studies have demonstrated the potential of circulating long non-coding RNAs (lncRNAs) as promising cancer biomarkers. Herein, we addressed the regulatory role of circulating lncRNAs and their potential value as diagnostic/prognostic markers for thyroid, pancreatic and ovarian cancers. Furthermore, we analyzed and measured the clinical implications and association of lncRNAs with sensitivity, specificity, and area under the ROC curve (AUC). Based on our meta-analysis, we found that GAS8-AS1 could discriminate thyroid cancer from non-cancer and other cancers with higher accuracy (AUC = 0.746; sensitivity = 61.70%, and specificity = 90.00%). Similarly, for ovarian cancer, lncRNA RP5-837J1.2 was found to have ideal diagnostic potential with critical clinical specifications of AUC = 0.996; sensitivity = 97.30% and specificity = 94.60%. Whereas we could not find any lncRNA having high diagnostic/prognostic efficiency in pancreatic cancer. We believe that lncRNAs mentioned above may explore clinical settings for the diagnosis and prognosis of cancer patients.

Nuclear Expression of Pygo2 Correlates with Poorly Differentiated State Involving c-Myc, PCNA and Bcl9 in Myanmar Hepatocellular Carcinoma

In Myanmar, hepatocellular carcinoma (HCC) is commonly seen in young adult and associated with poor prognosis, while the molecular mechanisms that characterize HCC in Myanmar are unknown. As co-activation of Wnt/β-catenin signaling and c-Myc (Myc) are reported to associate with malignancy of HCC, we immunohistochemically investigated the expression of Pygo2 and Bcl9, the co-activators of the Wnt/β-catenin signaling, Myc and PCNA in 60 cases of Myanmar HCC. Pygo2 expression was confirmed by in situ hybridization. The signal intensity was measured by image analyzer and then statistically analyzed. As a result, the expression of Pygo2 was significantly higher in HCC compared to normal liver tissue and the nuclear signal was the most intense in poorly differentiated HCC. Cytoplasmic Bcl9 was expressed in the normal liver tissue but decreased in HCC with the progression of histopathological grade. Myc was significantly higher in poorly differentiated HCC, whereas PCNA labeling index increased with the progression of histopathological grade. Nuclear Pygo2 showed strong correlation with nuclear Myc (P < 0.01) and PCNA (P < 0.001), and inversely correlated with cytoplasmic Bcl9 (P < 0.01). Our results suggested Wnt/β-catenin and Myc signaling is commonly activated in Myanmar HCC and that the correlative upregulation of nuclear Pygo2 and Myc characterizes the malignant features of HCC in Myanmar.

TBX3 acts as tissue-specific component of the Wnt/β-catenin transcriptional complex

BCL9 and PYGO are β-catenin cofactors that enhance the transcription of Wnt target genes. They have been proposed as therapeutic targets to diminish Wnt signaling output in intestinal malignancies. Here we find that, in colorectal cancer cells and in developing mouse forelimbs, BCL9 proteins sustain the action of β-catenin in a largely PYGO-independent manner. Our genetic analyses implied that BCL9 necessitates other interaction partners in mediating its transcriptional output. We identified the transcription factor TBX3 as a candidate tissue-specific member of the β-catenin transcriptional complex. In developing forelimbs, both TBX3 and BCL9 occupy a large number of Wnt-responsive regulatory elements, genome-wide. Moreover, mutations in Bcl9 affect the expression of TBX3 targets in vivo, and modulation of TBX3 abundance impacts on Wnt target genes transcription in a β-catenin- and TCF/LEF-dependent manner. Finally, TBX3 overexpression exacerbates the metastatic potential of Wnt-dependent human colorectal cancer cells. Our work implicates TBX3 as context-dependent component of the Wnt/β-catenin-dependent transcriptional complex.

Lactobacillus species inhibitory effect on colorectal cancer progression through modulating the Wnt/β-catenin signaling pathway

Probiotic bacteria are known to exert a wide range of anticancer activities on their animal hosts. In the present study, the anticancer effect of a cocktail of several potential probiotic Lactobacillus species (potential probiotic L.C) was investigated in vitro and in vivo. MTT and Flow cytometry tests results showed that administration of live potential probiotic L.C significantly decreased the HT-29 and CT-26 cells proliferation and induced late apoptotis in a time-dependent manner. In addition, quantitative real-time polymerase chain reaction (qPCR) results showed that exposure of potential probiotic L.C to both HT-29 and CT-26 cells during the incubation times resulted in the upregulation (apc and CSNK1ε for HT-29, CSNK1ε and gsk3β for CT-26) and downregulation (CTNNB1, CCND1, pygo2, axin2 and id2) of the Wnt/β- catenin pathway-related genes in a time-dependent manner. The significance of in vitro anticancer effect of potential probiotic L.C was further confirmed in an experimental tumor model. Data from the murine model of colorectal cancer (CRC) induced by Azoxymethane (AOM) and Dextran Sulfate Sodium (DSS) showed significantly alleviated inflammation and tumor development in AOM/DSS/L.C-injected mice compared to the AOM/DSS-injected mice. Tumor growth inhibition was accompanied by potential probiotic L.C-driven upregulation and downregulation of the Wnt/β-catenin pathway-related genes, similar to the in vitro results. These results showed that potential probiotic L.C inhibited the tumor growth, and that its anticancer activity was at least partially mediated through suppressing the Wnt/β-catenin pathway. Overall, the present study suggested that this probiotic could be used clinically as a supplement for CRC prevention and treatment.

Augmentation of Myc-Dependent Mitotic Gene Expression by the Pygopus2 Chromatin Effector

Mitotic segregation of chromosomes requires precise coordination of many factors, yet evidence is lacking as to how genes encoding these elements are transcriptionally controlled. Here, we found that the Pygopus (Pygo)2 chromatin effector is indispensable for expression of the MYC-dependent genes that regulate cancer cell division. Depletion of Pygo2 arrested SKOV-3 cells at metaphase, which resulted from the failure of chromosomes to capture spindle microtubules, a critical step for chromosomal biorientation and segregation. This observation was consistent with global chromatin association findings in HeLa S3 cells, revealing the enrichment of Pygo2 and MYC at promoters of biorientation and segmentation genes, at which Pygo2 maintained histone H3K27 acetylation. Immunoprecipitation and proximity ligation assays demonstrated MYC and Pygo2 interacting in nuclei, corroborated in a heterologous MYC-driven prostate cancer model that was distinct from Wnt/β-catenin signaling. Our evidence supports a role for Pygo2 as an essential component of MYC oncogenic activity required for mitosis.

LOTUS: A single- and multitask machine learning algorithm for the prediction of cancer driver genes

Cancer driver genes, i.e., oncogenes and tumor suppressor genes, are involved in the acquisition of important functions in tumors, providing a selective growth advantage, allowing uncontrolled proliferation and avoiding apoptosis. It is therefore important to identify these driver genes, both for the fundamental understanding of cancer and to help finding new therapeutic targets or biomarkers. Although the most frequently mutated driver genes have been identified, it is believed that many more remain to be discovered, particularly for driver genes specific to some cancer types. In this paper, we propose a new computational method called LOTUS to predict new driver genes. LOTUS is a machine-learning based approach which allows to integrate various types of data in a versatile manner, including information about gene mutations and protein-protein interactions. In addition, LOTUS can predict cancer driver genes in a pan-cancer setting as well as for specific cancer types, using a multitask learning strategy to share information across cancer types. We empirically show that LOTUS outperforms five other state-of-the-art driver gene prediction methods, both in terms of intrinsic consistency and prediction accuracy, and provide predictions of new cancer genes across many cancer types.

Cancer development is driven by mutations and dysfunction of important, so-called cancer driver genes, that could be targeted by specific therapies. While a number of such cancer genes have already been identified, it is believed that many more remain to be discovered. To help prioritize experimental investigations of candidate genes, several computational methods have been proposed to rank promising candidates based on their mutations in large cohorts of cancer cases, or on their interactions with known driver genes in biological networks. We propose LOTUS, a new computational approach to identify genes with high oncogenic potential. LOTUS implements a machine learning approach to learn an oncogenic potential score from known driver genes, and brings two novelties compared to existing methods. First, it allows to easily combine heterogeneous sources of information into the scoring function, which we illustrate by learning a scoring function from both known mutations in large cancer cohorts and interactions in biological networks. Second, using a multitask learning strategy, it can predict different driver genes for different cancer types, while sharing information between them to improve the prediction for every type. We provide experimental results showing that LOTUS significantly outperforms several state-of-the-art cancer gene prediction software.

PYGO2 as an independent diagnostic marker expressed in a majority of colorectal cancers

Colorectal cancer (CRC) is one of the most common gastrointestinal cancers worldwide. Detection of CRC at the early stages of disease can play an important role in decrease of associated mortality rates. The Wnt signaling pathway is crucial for the progression of different cellular and developmental processes and Wnt pathway deregulation has been well characterized in a variety of cancers, particularly in CRC. The aim of this study was to analyze protein expression of Pygopus2 (PYGO2), the main transcription factor of Wnt pathway, in CRC tissues and evaluate its probable correlation with clinicopathological features of the patients. The expression pattern of PYGO2 was evaluated by immunohistochemistry in tumor tissues and their margin normal which is the piece of normal, or unaffected tissue excised from the surrounding the visible tumors in 46 CRC patients. A defined scoring system was applied to analyze immunostaining results. The expression of PYGO2 protein was detected in all tumor tissues. Furthermore, this expression was significantly higher in CRC samples than in normal tissues. There was a significant association between PYGO2 protein expression in CRC and tumor cell metastasis to the lymph nodes. Considering the significant expression of PYGO2 protein in colorectal tumor cells and its correlation with lymph node metastasis, this protein may be used as a biomarker for metastatic CRC as well as a putative therapeutic target to inhibit aggressiveness and metastasis of CRC.

Bcl9 and Pygo synergise downstream of Apc to effect intestinal neoplasia in FAP mouse models

Bcl9 and Pygo are Wnt enhanceosome components that effect β-catenin-dependent transcription. Whether they mediate β-catenin-dependent neoplasia is unclear. Here we assess their roles in intestinal tumourigenesis initiated by Apc loss-of-function (ApcMin), or by Apc1322T encoding a partially-functional Apc truncation commonly found in colorectal carcinomas. Intestinal deletion of Bcl9 extends disease-free survival in both models, and essentially cures Apc1322T mice of their neoplasia. Loss-of-Bcl9 synergises with loss-of-Pygo to shift gene expression within Apc-mutant adenomas from stem cell-like to differentiation along Notch-regulated secretory lineages. Bcl9 loss also promotes tumour retention in ApcMin mice, apparently via relocating nuclear β-catenin to the cell surface, but this undesirable effect is not seen in Apc1322T mice whose Apc truncation retains partial function in regulating β-catenin. Our results demonstrate a key role of the Wnt enhanceosome in β-catenin-dependent intestinal tumourigenesis and reveal the potential of BCL9 as a therapeutic target during early stages of colorectal cancer.

The Effects of Berberine on the Gut Microbiota in Apc min/+ Mice Fed with a High Fat Diet

Background: Berberine (BBR) has been extensively reported to inhibit colorectal cancer (CRC) development, though its bioavailability is poor. Nowadays, an increasing number of studies have shown that BBR significantly accumulates in the intestines and could regulate gut microbiota in obesity. The purpose of this study was to further explore the effects of BBR on gut microbiota in Apc ^min/+ mice receiving a high fat diet (HFD). Methods: Apc ^min/+ mice received either HFD alone or HFD and BBR for 12 weeks. The intestinal tissues were collected to evaluate the efficiency of BBR on neoplasm development by hematoxylin and eosin staining. Meanwhile, immunohistochemistry was conducted to investigate the effects of BBR on cyclin D1 and β-catenin in colon tissues. Fecal samples were subjected to 16S rRNA sequencing. Results: BBR significantly reduced intestinal tumor development and altered the structure of gut microbiota in Apc ^min/+ mice fed with an HFD. At the phylum level, it was able to significantly inhibit the increase in Verrucomicrobia. At the genus level, it was able to suppress Akkermansia and elevate some short chain fat acid (SCFA)-producing bacteria. Conclusions: BBR significantly alleviated the development of CRC in Apc ^min/+ mice fed with HFD and restored the enteric microbiome community.

An In Vivo Screen Identifies PYGO2 as a Driver for Metastatic Prostate Cancer

Advanced prostate cancer displays conspicuous chromosomal instability and rampant copy number aberrations, yet the identity of functional drivers resident in many amplicons remain elusive. Here, we implemented a functional genomics approach to identify new oncogenes involved in prostate cancer progression. Through integrated analyses of focal amplicons in large prostate cancer genomic and transcriptomic datasets as well as genes upregulated in metastasis, 276 putative oncogenes were enlisted into an in vivo gain-of-function tumorigenesis screen. Among the top positive hits, we conducted an in-depth functional analysis on Pygopus family PHD finger 2 (PYGO2), located in the amplicon at 1q21.3. PYGO2 overexpression enhances primary tumor growth and local invasion to draining lymph nodes. Conversely, PYGO2 depletion inhibits prostate cancer cell invasion in vitro and progression of primary tumor and metastasis in vivo In clinical samples, PYGO2 upregulation associated with higher Gleason score and metastasis to lymph nodes and bone. Silencing PYGO2 expression in patient-derived xenograft models impairs tumor progression. Finally, PYGO2 is necessary to enhance the transcriptional activation in response to ligand-induced Wnt/β-catenin signaling. Together, our results indicate that PYGO2 functions as a driver oncogene in the 1q21.3 amplicon and may serve as a potential prognostic biomarker and therapeutic target for metastatic prostate cancer.Significance: Amplification/overexpression of PYGO2 may serve as a biomarker for prostate cancer progression and metastasis. Cancer Res; 78(14); 3823-33. ©2018 AACR.

Canonical WNT/β-Catenin Signaling Plays a Subordinate Role in Rhabdomyosarcomas

The development of skeletal muscle from immature precursors is partially driven by canonical WNT/β-catenin signaling. Rhabdomyosarcomas (RMS) are immature skeletal muscle-like, highly lethal cancers with a variably pronounced blockade of muscle differentiation. To investigate whether canonical β-catenin signaling in RMS is involved in differentiation and aggressiveness of RMS, we analyzed the effects of WNT3A and of a siRNA-mediated or pharmacologically induced β-catenin knock-down on proliferation, apoptosis and differentiation of embryonal and alveolar RMS cell lines. While the canonical WNT pathway was maintained in all cell lines as shown by WNT3A induced AXIN expression, more distal steps including transcriptional activation of its key target genes were consistently impaired. In addition, activation or inhibition of canonical WNT/β-catenin only moderately affected proliferation, apoptosis or myodifferentiation of the RMS tumor cells and a conditional knockout of β-catenin in RMS of Ptch ^del/+ mice did not alter RMS incidence or multiplicity. Together our data indicates a subordinary role of the canonical WNT/β-catenin signaling for RMS proliferation, apoptosis or differentiation and thus aggressiveness of this malignant childhood tumor.

Pharmacological interventions in the Wnt pathway: inhibition of Wnt secretion versus disrupting the protein-protein interfaces of nuclear factors

Mutations in components of the Wnt pathways are a frequent cause of many human diseases, particularly cancer. Despite the fact that a causative link between aberrant Wnt signalling and many types of human cancers was established more than a decade ago, no Wnt signalling inhibitors have made it into the clinic so far. One reason for this is that no pathway-specific kinase is known. Additionally, targeting the protein-protein interactions needed to transduce the signal has not met with success so far. Complicating the search for and use of inhibitors is the complexity of the cascades triggered by the Wnts and their paramount biological importance. Wnt/β-catenin signalling is involved in virtually all aspects of embryonic development and in the control of the homeostasis of adult tissues. Encouragingly, however, in recent years, first successes with Wnt-pathway inhibitors have been reported in mouse models of disease. In this review, we summarize possible roads to follow during the quest to pharmacologically modulate the Wnt signalling pathway in cancer.

LINKED ARTICLES

This article is part of a themed section on WNT Signalling: Mechanisms and Therapeutic Opportunities. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.24/issuetoc.