WNT inhibition creates a BRCA-like state in Wnt-addicted cancer

Epigenetic silencing ZSCAN23 promotes pancreatic cancer growth by activating Wnt signaling

Pancreatic ductal adenocarcinoma (PDAC) is the most malignant tumor. Zinc finger and SCAN domain-containing protein 23 (ZSCAN23) is a new member of the SCAN domain family. The expression regulation and biological function remain to be elucidated. In this study, we explored the epigenetic regulation and the function of ZSCAN23 in PDAC. ZSCAN23 was methylated in 60.21% (171/284) of PDAC and its expression was regulated by promoter region methylation. The expression of ZSCAN23 inhibited cell proliferation, colony formation, migration, invasion, and induced apoptosis and G1/S phase arrest. ZSCAN23 suppressed Panc10.05 cell xenograft growth in mice. Mechanistically, ZSCAN23 inhibited Wnt signaling by interacting with myosin heavy chain 9 (MYH9) in pancreatic cancer cells. ZSCAN23 is frequently methylated in PDAC and may serve as a detective marker. ZSCAN23 suppresses PDAC cell growth both in vitro and in vivo.

PARP1-stabilised FOXQ1 promotes ovarian cancer progression by activating the LAMB3/WNT/β-catenin signalling pathway

Metastasis is an important factor that causes ovarian cancer (OC) to become the most lethal malignancy of the female reproductive system, but its molecular mechanism is not fully understood. In this study, through bioinformatics analysis, as well as analysis of tissue samples and clinicopathological characteristics and prognosis of patients in our centre, it was found that Forkhead box Q1 (FOXQ1) was correlated with metastasis and prognosis of OC. Through cell function experiments and animal experiments, the results show that FOXQ1 can promote the progression of ovarian cancer in vivo and in vitro. Through RNA-seq, chromatin immunoprecipitation sequencing (ChIP-seq), Kyoto Encyclopedia of Genes and Genomes (KEGG), gene set enrichment analysis (GSEA), Western blotting (WB), quantitative real-time polymerase chain reaction (qRT‒PCR), immunohistochemistry (IHC), luciferase assay, and ChIP-PCR, it was demonstrated that FOXQ1 can mediate the WNT/β-catenin pathway by targeting the LAMB promoter region. Through coimmunoprecipitation (Co-IP), mass spectrometry (MS), ubiquitination experiments, and immunofluorescence (IF), the results showed that PARP1 could stabilise FOXQ1 expression via the E3 ubiquitin ligase Hsc70-interacting protein (CHIP). Finally, the whole mechanism pathway was verified by animal drug combination experiments and clinical specimen prognosis analysis. In summary, our results suggest that PARP1 can promote ovarian cancer progression through the LAMB3/WNT/β-catenin pathway by stabilising FOXQ1 expression.

The cholesterol biosynthesis enzyme FAXDC2 couples Wnt/β-catenin to RTK/MAPK signaling

Wnts, cholesterol, and MAPK signaling are essential for development and adult homeostasis. Here, we report that fatty acid hydroxylase domain containing 2 (FAXDC2), a previously uncharacterized enzyme, functions as a methyl sterol oxidase catalyzing C4 demethylation in the Kandutsch-Russell branch of the cholesterol biosynthesis pathway. FAXDC2, a paralog of MSMO1, regulated the abundance of the specific C4-methyl sterols lophenol and dihydro-T-MAS. Highlighting its clinical relevance, FAXDC2 was repressed in Wnt/β-catenin-high cancer xenografts, in a mouse genetic model of Wnt activation, and in human colorectal cancers. Moreover, in primary human colorectal cancers, the sterol lophenol, regulated by FAXDC2, accumulated in the cancerous tissues and not in adjacent normal tissues. FAXDC2 linked Wnts to RTK/MAPK signaling. Wnt inhibition drove increased recycling of RTKs and activation of the MAPK pathway, and this required FAXDC2. Blocking Wnt signaling in Wnt-high cancers caused both differentiation and senescence; and this was prevented by knockout of FAXDC2. Our data show the integration of 3 ancient pathways, Wnts, cholesterol synthesis, and RTK/MAPK signaling, in cellular proliferation and differentiation.

Integrated transcriptome and cell phenotype analysis suggest involvement of PARP1 cleavage, Hippo/Wnt, TGF-β and MAPK signaling pathways in ovarian cancer cells response to cannabis and PARP1 inhibitor treatment

Introduction: Cannabis sativa is utilized mainly for palliative care worldwide. Ovarian cancer (OC) is a lethal gynecologic cancer. A particular cannabis extract fraction ('F7') and the Poly(ADP-Ribose) Polymerase 1 (PARP1) inhibitor niraparib act synergistically to promote OC cell apoptosis. Here we identified genetic pathways that are altered by the synergistic treatment in OC cell lines Caov3 and OVCAR3. Materials and methods: Gene expression profiles were determined by RNA sequencing and quantitative PCR. Microscopy was used to determine actin arrangement, a scratch assay to determine cell migration and flow cytometry to determine apoptosis, cell cycle and aldehyde dehydrogenase (ALDH) activity. Western blotting was used to determine protein levels. Results: Gene expression results suggested variations in gene expression between the two cell lines examined. Multiple genetic pathways, including Hippo/Wnt, TGF-β/Activin and MAPK were enriched with genes differentially expressed by niraparib and/or F7 treatments in both cell lines. Niraparib + F7 treatment led to cell cycle arrest and endoplasmic reticulum (ER) stress, inhibited cell migration, reduced the % of ALDH positive cells in the population and enhanced PARP1 cleavage. Conclusion: The synergistic effect of the niraparib + F7 may result from the treatment affecting multiple genetic pathways involving cell death and reducing mesenchymal characteristics.

Hallmarks of stemness in mammalian tissues

All adult tissues experience wear and tear. Most tissues can compensate for cell loss through the activity of resident stem cells. Although the cellular maintenance strategies vary greatly between different adult (read: postnatal) tissues, the function of stem cells is best defined by their capacity to replace lost tissue through division. We discuss a set of six complementary hallmarks that are key enabling features of this basic function. These include longevity and self-renewal, multipotency, transplantability, plasticity, dependence on niche signals, and maintenance of genome integrity. We discuss these hallmarks in the context of some of the best-understood adult stem cell niches.

ELISL: early-late integrated synthetic lethality prediction in cancer

MOTIVATION

Anti-cancer therapies based on synthetic lethality (SL) exploit tumour vulnerabilities for treatment with reduced side effects, by targeting a gene that is jointly essential with another whose function is lost. Computational prediction is key to expedite SL screening, yet existing methods are vulnerable to prevalent selection bias in SL data and reliant on cancer or tissue type-specific omics, which can be scarce. Notably, sequence similarity remains underexplored as a proxy for related gene function and joint essentiality.

RESULTS

We propose ELISL, Early-Late Integrated SL prediction with forest ensembles, using context-free protein sequence embeddings and context-specific omics from cell lines and tissue. Across eight cancer types, ELISL showed superior robustness to selection bias and recovery of known SL genes, as well as promising cross-cancer predictions. Co-occurring mutations in a BRCA gene and ELISL-predicted pairs from the HH, FGF, WNT, or NEIL gene families were associated with longer patient survival times, revealing therapeutic potential.

AVAILABILITY AND IMPLEMENTATION

Data: 10.6084/m9.figshare.23607558 & Code: github.com/joanagoncalveslab/ELISL.

Single-cell transcriptomics identifies a WNT7A-FZD5 signaling axis that maintains fallopian tube stem cells in patient-derived organoids

The study of fallopian tube (FT) function in health and disease has been hampered by limited knowledge of FT stem cells and lack of in vitro models of stem cell renewal and differentiation. Using optimized organoid culture conditions to address these limitations, we find that FT stem cell renewal is highly dependent on WNT/β-catenin signaling and engineer endogenous WNT/β-catenin signaling reporter organoids to biomark, isolate, and characterize these cells. Using functional approaches, as well as bulk and single-cell transcriptomics analyses, we show that an endogenous hormonally regulated WNT7A-FZD5 signaling axis is critical for stem cell renewal and that WNT/β-catenin pathway-activated cells form a distinct transcriptomic cluster of FT cells enriched in extracellular matrix (ECM) remodeling and integrin signaling pathways. Overall, we provide a deep characterization of FT stem cells and their molecular requirements for self-renewal, paving the way for mechanistic work investigating the role of stem cells in FT health and disease.

The time-resolved genomic impact of Wnt/β-catenin signaling

Wnt signaling orchestrates gene expression via its effector, β-catenin. However, it is unknown whether β-catenin binds its target genomic regions simultaneously and how this impacts chromatin dynamics to modulate cell behavior. Using a combination of time-resolved CUT&RUN against β-catenin, ATAC-seq, and perturbation assays in different cell types, we show that Wnt/β-catenin physical targets are tissue-specific, β-catenin "moves" on different loci over time, and its association to DNA accompanies changing chromatin accessibility landscapes that determine cell behavior. In particular, Wnt/β-catenin progressively shapes the chromatin of human embryonic stem cells (hESCs) as they undergo mesodermal differentiation, a behavior that we define as "plastic." In HEK293T cells, on the other hand, Wnt/β-catenin drives a transient chromatin opening, followed by re-establishment of the pre-stimulation state, a response that we define as "elastic." Future experiments shall assess whether other cell communication mechanisms, in addition to Wnt signaling, are ruled by time, cellular idiosyncrasies, and chromatin constraints. A record of this paper's transparent peer review process is included in the supplemental information.

Tumor cell plasticity in targeted therapy-induced resistance: mechanisms and new strategies

Despite the success of targeted therapies in cancer treatment, therapy-induced resistance remains a major obstacle to a complete cure. Tumor cells evade treatments and relapse via phenotypic switching driven by intrinsic or induced cell plasticity. Several reversible mechanisms have been proposed to circumvent tumor cell plasticity, including epigenetic modifications, regulation of transcription factors, activation or suppression of key signaling pathways, as well as modification of the tumor environment. Epithelial-to-mesenchymal transition, tumor cell and cancer stem cell formation also serve as roads towards tumor cell plasticity. Corresponding treatment strategies have recently been developed that either target plasticity-related mechanisms or employ combination treatments. In this review, we delineate the formation of tumor cell plasticity and its manipulation of tumor evasion from targeted therapy. We discuss the non-genetic mechanisms of targeted drug-induced tumor cell plasticity in various types of tumors and provide insights into the contribution of tumor cell plasticity to acquired drug resistance. New therapeutic strategies such as inhibition or reversal of tumor cell plasticity are also presented. We also discuss the multitude of clinical trials that are ongoing worldwide with the intention of improving clinical outcomes. These advances provide a direction for developing novel therapeutic strategies and combination therapy regimens that target tumor cell plasticity.

The Roles of Secreted Wnt Ligands in Cancer

Wnt ligands are secreted signaling proteins that display a wide range of biological effects. They play key roles in stimulating Wnt signaling pathways to facilitate processes such as tissue homeostasis and regeneration. Dysregulation of Wnt signaling is a hallmark of many cancers and genetic alterations in various Wnt signaling components, which result in ligand-independent or ligand-dependent hyperactivation of the pathway that have been identified. Recently, research is focusing on the impact of Wnt signaling on the interaction between tumor cells and their micro-environment. This Wnt-mediated crosstalk can act either in a tumor promoting or suppressing fashion. In this review, we comprehensively outline the function of Wnt ligands in different tumor entities and their impact on key phenotypes, including cancer stemness, drug resistance, metastasis, and immune evasion. Lastly, we elaborate approaches to target Wnt ligands in cancer therapy.

PMCA inhibition reverses drug resistance in clinically refractory cancer patient-derived models

BACKGROUND

Cancer cells have developed molecular strategies to cope with evolutionary stressors in the dynamic tumor microenvironment. Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α) is a metabolic rheostat that regulates diverse cellular adaptive behaviors, including growth and survival. However, the mechanistic role of PGC1α in regulating cancer cell viability under metabolic and genotoxic stress remains elusive.

METHODS

We investigated the PGC1α-mediated survival mechanisms in metabolic stress (i.e., glucose deprivation-induced metabolic stress condition)-resistant cancer cells. We established glucose deprivation-induced metabolic stress-resistant cells (selected cells) from parental tumor cells and silenced or overexpressed PGC1α in selected and parental tumor cells.

RESULTS

Several in vitro and in vivo mouse experiments were conducted to elucidate the contribution of PGC1α to cell viability in metabolic stress conditions. Interestingly, in the mouse xenograft model of patient-derived drug-resistant cancer cells, each group treated with an anti-cancer drug alone showed no drastic effects, whereas a group that was co-administered an anti-cancer drug and a specific PMCA inhibitor (caloxin or candidate 13) showed marked tumor shrinkage.

CONCLUSIONS

Our results suggest that PGC1α is a key regulator of anti-apoptosis in metabolic and genotoxic stress-resistant cells, inducing PMCA expression and allowing survival in glucose-deprived conditions. We have discovered a novel therapeutic target candidate that could be employed for the treatment of patients with refractory cancers.

β-Catenin activity induces an RNA biosynthesis program promoting therapy resistance in T-cell acute lymphoblastic leukemia

Understanding the molecular mechanisms that contribute to the appearance of chemotherapy resistant cell populations is necessary to improve cancer treatment. We have now investigated the role of β-catenin/CTNNB1 in the evolution of T-cell Acute Lymphoblastic Leukemia (T-ALL) patients and its involvement in therapy resistance. We have identified a specific gene signature that is directly regulated by β-catenin, TCF/LEF factors and ZBTB33/Kaiso in T-ALL cell lines, which is highly and significantly represented in five out of six refractory patients from a cohort of 40 children with T-ALL. By subsequent refinement of this gene signature, we found that a subset of β-catenin target genes involved with RNA-processing function are sufficient to segregate T-ALL refractory patients in three independent cohorts. We demonstrate the implication of β-catenin in RNA and protein synthesis in T-ALL and provide in vitro and in vivo experimental evidence that β-catenin is crucial for the cellular response to chemotherapy, mainly in the cellular recovery phase after treatment. We propose that combination treatments involving chemotherapy plus β-catenin inhibitors will enhance chemotherapy response and prevent disease relapse in T-ALL patients.

Blocking the Wnt/β‑catenin signaling pathway to treat colorectal cancer: Strategies to improve current therapies (Review)

Colorectal cancer (CRC) is one of the most common malignant tumor types occurring in the digestive system. The incidence of CRC has exhibits yearly increases and the mortality rate among patients with CRC is high. The Wnt/β‑catenin signaling pathway, which is associated with carcinogenesis, is abnormally activated in CRC. Most patients with CRC have adenomatous polyposis coli mutations, while half of the remaining patients have β‑catenin gene mutations. Therefore, targeting the Wnt/β‑catenin signaling pathway for the treatment of CRC is of clinical value. In recent years, with in‑depth research on the Wnt/β‑catenin signaling pathway, inhibitors have been developed that are able to suppress or hinder the development and progression of CRC. In the present review, the role of the Wnt/β‑catenin signaling pathway in CRC is summarized, the research status on Wnt/β‑catenin pathway inhibitors is outlined and potential targets for inhibition of this pathway are presented.

Phytocannabinoid Compositions from Cannabis Act Synergistically with PARP1 Inhibitor against Ovarian Cancer Cells In Vitro and Affect the Wnt Signaling Pathway

Ovarian cancer (OC) is the single most lethal gynecologic malignancy. Cannabis sativa is used to treat various medical conditions, and is cytotoxic to a variety of cancer types. We sought to examine the effectiveness of different combinations of cannabis compounds against OC. Cytotoxic activity was determined by XTT assay on HTB75 and HTB161 cell lines. Apoptosis was determined by flow cytometry. Gene expression was determined by quantitative PCR and protein localization by confocal microscopy. The two most active fractions, F5 and F7, from a high Δ9-tetrahydrocannabinol (THC) cannabis strain extract, and their standard mix (SM), showed cytotoxic activity against OC cells and induced cell apoptosis. The most effective phytocannabinoid combination was THC+cannabichromene (CBC)+cannabigerol (CBG). These fractions acted in synergy with niraparib, a PARP inhibitor, and were ~50-fold more cytotoxic to OC cells than to normal keratinocytes. The F7 and/or niraparib treatments altered Wnt pathway-related gene expression, epithelial-mesenchymal transition (EMT) phenotype and β-catenin cellular localization. The niraparib+F7 treatment was also effective on an OC patient's cells. Given the fact that combinations of cannabis compounds and niraparib act in synergy and alter the Wnt signaling pathway, these phytocannabinoids should be examined as effective OC treatments in further pre-clinical studies and clinical trials.

Targeting ligand-dependent wnt pathway dysregulation in gastrointestinal cancers through porcupine inhibition

Gastrointestinal cancers are responsible for more cancer deaths than any other system of the body. This review summarises how Wnt pathway dysregulation contributes to the development of the most common gastrointestinal cancers, with a particular focus on the nature and frequency of upstream pathway aberrations. Tumors with upstream aberrations maintain a dependency on the presence of functional Wnt ligand, and are predicted to be tractable to inhibitors of Porcupine, an enzyme that plays a key role in Wnt secretion. We summarise available pre-clinical efficacy data from Porcupine inhibitors in vitro and in vivo, as well as potential toxicities and the data from early phase clinical trials. We appraise the rationale for biomarker-defined targeted approaches, as well as outlining future opportunities for combination with other therapeutics.

The Wnt Pathway: From Signaling Mechanisms to Synthetic Modulators

The Wnt pathway is central to a host of developmental and disease-related processes. The remarkable conservation of this intercellular signaling cascade throughout metazoan lineages indicates that it coevolved with multicellularity to regulate the generation and spatial arrangement of distinct cell types. By regulating cell fate specification, mitotic activity, and cell polarity, Wnt signaling orchestrates development and tissue homeostasis, and its dysregulation is implicated in developmental defects, cancer, and degenerative disorders. We review advances in our understanding of this key pathway, from Wnt protein production and secretion to relay of the signal in the cytoplasm of the receiving cell. We discuss the evolutionary history of this pathway as well as endogenous and synthetic modulators of its activity. Finally, we highlight remaining gaps in our knowledge of Wnt signal transduction and avenues for future research. Expected final online publication date for the Annual Review of Biochemistry, Volume 91 is June 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

The multidimensional role of the Wnt/β-catenin signaling pathway in human malignancies

Several signaling pathways have been identified as important for developmental processes. One of such important cascades is the Wnt/β-catenin signaling pathway, which can regulate various physiological processes such as embryonic development, tissue homeostasis, and tissue regeneration; while its dysregulation is implicated in several pathological conditions especially cancers. Interestingly, deregulation of the Wnt/β-catenin pathway has been reported to be closely associated with initiation, progression, metastasis, maintenance of cancer stem cells, and drug resistance in human malignancies. Moreover, several genetic and experimental models support the inhibition of the Wnt/β-catenin pathway to answer the key issues related to cancer development. The present review focuses on different regulators of Wnt pathway and how distinct mutations, deletion, and amplification in these regulators could possibly play an essential role in the development of several cancers such as colorectal, melanoma, breast, lung, and leukemia. Additionally, we also provide insights on diverse classes of inhibitors of the Wnt/β-catenin pathway, which are currently in preclinical and clinical trial against different cancers.

WNT Signaling as a Therapeutic Target for Glioblastoma

The WNT (Wingless/Integrated) signaling pathway is implicated in various stages of glioblastoma, which is an aggressive brain tumor for which therapeutic options are limited. WNT has been recognized as a hallmark of therapeutic challenge due to its context-dependent role and critical function in healthy tissue homeostasis. In this review, we deeply scrutinize the WNT signaling pathway and its involvement in the genesis of glioblastoma as well as its acquired therapy resistance. We also provide an analysis of the WNT pathway in terms of its therapeutic importance in addition to an overview of the current targeted therapies under clinical investigation.

Wnt signaling inhibition confers induced synthetic lethality to PARP inhibitors

Despite considerable efforts, therapeutic strategies targeting the Wnt pathway are still not clinically available. The pervasive role of Wnt‐βcatenin signaling for the control of stem cells during normal tissue homeostasis makes the on‐target toxicity of available therapeutic grade molecules an important limitation preventing their clinical introduction. The article in this issue of EMBO Molecular Medicine by Kaur et al (2021) reveals that treatment of Wnt‐addicted cancer cells with inhibitors of Wnt signaling induces a state of BRCAness leading to hypersensitivity to PARP inhibitors. This is a new example of induced synthetic lethality that could pave the way for new indications for PARP inhibitors or may contribute to the long‐awaited clinical introduction of therapeutic agents targeting the Wnt pathway.