Small-molecule antagonists of the oncogenic Tcf/beta-catenin protein complex

Protacs in cancer therapy: mechanisms, design, clinical trials, and future directions

Cancer develops as a result of changes in both genetic and epigenetic mechanisms, which lead to the activation of oncogenes and the suppression of tumor suppressor genes. Despite advancements in cancer treatments, the primary approach still involves a combination of chemotherapy, radiotherapy, and surgery, typically providing a median survival of approximately five years for patients. Unfortunately, these therapeutic interventions often bring about substantial side effects and toxicities, significantly impacting the overall quality of life for individuals undergoing treatment. Therefore, urgent need of research required which comes up with effective treatment of cancer. This review explores the transformative role of Proteolysis-Targeting Chimeras (PROTACs) in cancer therapy. PROTACs, an innovative drug development strategy, utilize the cell's protein degradation machinery to selectively eliminate disease-causing proteins. The review covers the historical background, mechanism of action, design, and structure of PROTACs, emphasizing their precision in targeting oncogenic proteins. The discussion extends to the challenges, nanotechnology applications, and ongoing clinical trials, showcasing promising results and clinical progress. The review concludes with insights into patents, future directions, and the potential impact of PROTACs in addressing dysregulated protein expression across various diseases. Overall, it provides a concise yet comprehensive overview for researchers, clinicians, and industry professionals involved in developing targeted therapies.

Perspectives on cancer therapy-synthetic lethal precision medicine strategies, molecular mechanisms, therapeutic targets and current technical challenges

In recent years, synthetic lethality has become an important theme in the field of targeted cancer therapy. Synthetic lethality refers to simultaneous defects in two or more genes leading to cell death, whereas defects in any single gene do not lead to cell death. Taking advantage of the genetic vulnerability that exists within cancer cells, it theoretically has no negative impact on healthy cells and has fewer side effects than non-specific chemotherapy. Currently, targeted cancer therapies focus on inhibiting key pathways in cancer. However, it has been found that over-activation of oncogenic-related signaling pathways can also induce cancer cell death, which is a major breakthrough in the new field of targeted therapies. In this review, we summarize the conventional gene targets in synthetic lethality (PARP, ATR, ATM, WEE1, PRMT) and provide an in-depth analysis of their latest potential mechanisms. We explore the impact of over-activation of pathways such as PI3K/AKT, MAPK, and WNT on cancer cell survival, and present the technical challenges of current research. Important theoretical foundations and insights are provided for the application of synthetic lethal strategies in cancer therapy, as well as future research directions.

Mutational signatures define immune and Wnt-associated subtypes of ampullary carcinoma

BACKGROUND AND OBJECTIVE

Ampullary carcinoma (AMPAC) taxonomy is based on morphology and immunohistochemistry. This classification lacks prognostic reliability and unique genetic associations. We applied an approach of integrative genomics characterising patients with AMPAC exploring molecular subtypes that may guide personalised treatments.

DESIGN

We analysed the mutational landscapes of 170 patients with AMPAC. The discovery included 110 tumour/normal pairs and the validation comprised 60 patients. In a tumour subset, we interrogated the transcriptomes and DNA methylomes. Patients were stratified based on mutational signatures and associated with molecular and clinical features. To evaluate tumour and immune cellularity, 22 tumours were independently assessed histomorphologically and by digital pathology.

RESULTS

We defined three patient clusters by mutational signatures independent of histomorphology. Cluster 1 (C1) was defined by spontaneous deamination of DNA 5-methylcytosine and defective mismatch repair. C2 and C3 were related to the activity of transcription-coupled nucleotide excision repair but C3 was further defined by the polymerase eta mutational process. C1-2 showed enrichment of Wnt pathway alterations, aberrant DNA methylation profiles, immune cell exclusion and patients with poor prognosis. These features were associated with a hypermutator phenotype caused by C>T alterations at CpGs. C3 patients with improved overall survival were associated with activation of immune-related pathways, immune infiltration and elevated expression of immunoinhibitory checkpoint genes.

CONCLUSION

Immunogenicity and Wnt pathway associations, emphasised by the mutational signatures, defined patients with prospective sensitivity to either immunotherapy or Wnt pathway inhibitors. This emphasises a novel mutational signature-based AMPAC classification with prognostic potential, suggesting prospective implications for subgroup-specific management of patients with AMPAC.

Wnt signaling pathways in biology and disease: mechanisms and therapeutic advances

The Wnt signaling pathway is critically involved in orchestrating cellular functions such as proliferation, migration, survival, and cell fate determination during development. Given its pivotal role in cellular communication, aberrant Wnt signaling has been extensively linked to the pathogenesis of various diseases. This review offers an in-depth analysis of the Wnt pathway, detailing its signal transduction mechanisms and principal components. Furthermore, the complex network of interactions between Wnt cascades and other key signaling pathways, such as Notch, Hedgehog, TGF-β, FGF, and NF-κB, is explored. Genetic mutations affecting the Wnt pathway play a pivotal role in disease progression, with particular emphasis on Wnt signaling's involvement in cancer stem cell biology and the tumor microenvironment. Additionally, this review underscores the diverse mechanisms through which Wnt signaling contributes to diseases such as cardiovascular conditions, neurodegenerative disorders, metabolic syndromes, autoimmune diseases, and cancer. Finally, a comprehensive overview of the therapeutic progress targeting Wnt signaling was given, and the latest progress in disease treatment targeting key components of the Wnt signaling pathway was summarized in detail, including Wnt ligands/receptors, β-catenin destruction complexes, and β-catenin/TCF transcription complexes. The development of small molecule inhibitors, monoclonal antibodies, and combination therapy strategies was emphasized, while the current potential therapeutic challenges were summarized. This aims to enhance the current understanding of this key pathway.

Fusobacterium nucleatum modulates the Wnt/β-catenin pathway in colorectal cancer development

The Wnt/β-catenin signalling pathway normally maintains cellular and tissue homeostasis by regulating cellular differentiation and survival in a controlled manner. An aberrantly regulated Wnt/β-catenin signalling pathway can transform into an oncogenic pathway, which is associated with Colorectal cancer (CRC) as well as other cancers. CRC is one of the most frequently occurring gastrointestinal cancers worldwide. In CRC tissues, deregulation of Wnt/β-catenin pathway is observed, which indicates that this oncogenic pathway directly promotes CRC malignancy, cell migration, angiogenesis, chemoresistance, as well as shorter lifespan of a patient. Growing evidence suggests that human commensal microbes have a strong association with carcinogenesis, particularly the prevalence and high enrichment of Fusobacterium nucleatum in CRC progression. The Wnt/β-catenin pathway is one of the targeted pathways by F. nucleatum in CRC, where Fusobacterium adhesin attaches to E-cadherin to initiate infection. Also, Wnt/β-catenin pathway can be a potential target for the treatment of both CRC and F. nucleatum-positive CRC. Here, we discuss the underlying mechanisms of F. nucleatum-positive CRC development through modulation of Wnt/β-catenin signalling and its possibility for the application in targeted therapy of F. nucleatum-positive CRC.

Discovery of a novel 2,4-thiazolidinedione derivative as dual inhibitor of β-catenin/TCF4 interaction and tubulin polymerization in colon cancer cells

Hyperactivation of the Wnt/β-catenin signaling pathway has been widely recognized as a pathogenic mechanism for colorectal cancer (CRC). Based on a previously reported lead compound, iCRT14, a series of 2,4-thiazolidinedione derivatives were designed, synthesized, and evaluated in vitro for their antiproliferative activity against colon cancer cells. Compound 15k exhibited the most potent activity against the HCT116 and SW480 cell lines. Compound 15k inhibited Wnt/β-catenin signaling by disrupting the protein-protein interactions between β-catenin and TCF4. Compound 15k simultaneously inhibited tubulin polymerization, disorganized the microtubule network, and arrested the cell cycle at the G2/M phase, offering an additional mechanism of action and 15k induced cell apoptosis by activating caspase-3 and poly(ADP-ribose) polymerase. Additionally, compound 15k inhibited cell migration without affecting the levels of β-catenin protein. These results offer guidance for developing the current series as potential new anticancer therapeutics.

Exploring the therapeutic potential of "Zhi-Zhen" formula for oxaliplatin resistance in colorectal cancer: an integrated study combining UPLC-QTOF-MS/MS, bioinformatics, network pharmacology, and experimental validation

Background

Chemoresistance is a critical factor compromising the survival of patients with colorectal cancer (CRC). The "Zhi-Zhen" formula (ZZF), a traditional prescription developed by Chinese national medicine masters, has been extensively used in clinical practice to treat gastrointestinal cancer. Notably, ZZF has the potential to enhance tumor sensitivity to chemotherapy. Although previous in vitro studies have demonstrated the efficacy of ZZF in overcoming chemoresistance in colorectal cancer (CRC), its precise molecular mechanisms remain poorly understood.

Materials and methods

We used an integrated approach of bioinformatics and network pharmacology to predict the potential active ingredients and targets of ZZF in alleviating chemoresistance. The top five active ingredients identified by degree in the network analysis were validated using mass spectrometry. We then established an oxaliplatin-resistant CRC cell model to explore the potential targets and regulatory mechanisms through which ZZF overcomes chemoresistance at the cellular level.

Results

Network pharmacology and bioinformatics analyses jointly identified 29 active compounds and 13 potential key targets of ZZF, associated with chemoresistance. Among these targets, the differential expression of CASP7 significantly affected the progression-free survival of patients with CRC. We established two oxaliplatin-resistant CRC cell lines and observed an upregulation of CASP7 expression in these resistant cells. Furthermore, ZZF increases the expression and activation of CASP7 in resistant cells, promoting apoptosis, and thereby ameliorating chemoresistance. Additionally, β-catenin knockdown led to an upregulation of CASP7 expression, whereas activation of the Wnt/β-catenin signaling pathway reduced CASP7 protein levels. ZZF decreases the activity of the Wnt/β-catenin signaling pathway by decreasing β-catenin transcription and nuclear localization.

Conclusion

ZZF has potential clinical value in the treatment of chemoresistance in CRC by inhibiting the transcription and nuclear localization of β-catenin, thereby increasing the expression of CASP7 and enhancing the apoptotic response in chemoresistant CRC cells.

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.

Regulation of Natural Products on Wnt/β-Catenin Signaling Pathway in Diseases

The Wnt/β-catenin signaling pathway plays a crucial role in both physiological and pathological conditions. Targeting molecules associated with the Wnt/β-catenin signaling pathway presents a promising approach for disease treatment. The use of natural products in treating various diseases is widespread due to their favorable biocompatibility, low toxicity, and high biological activity. Research has shown that natural products such as curcumin and resveratrol can regulate multiple signaling pathways under disease conditions, including the Wnt/β-catenin signaling pathway. However, the regulatory mechanisms of natural products remain incompletely understood. This review aims to explore the regulatory effects of natural products on the Wnt/β-catenin signaling pathway in certain diseases, especially in the process of tumor progression. It outlines the composition and mechanisms of the Wnt/β-catenin signaling pathway. Furthermore, we predicted the potential binding sites of these natural products to this pathway, summarized the effects of diverse natural products on this signaling pathway, and conducted a preliminary exploration ofd the mechanisms of the effects of natural products. In addition, we considered and discussed the limitations of natural products, such as potential side effects from long-term use and the precision in targeting the Wnt/β-catenin signaling pathway. This review provides a theoretical basis for the targeted strategy of the Wnt/β-catenin signaling pathway.

Wnt Signaling Pathway in Tumor Biology

Relapse and metastasis are the major challenges that stand in the way of cancer healing and survival, mainly attributed to cancer stem cells (CSCs). Their capabilities of self-renewal and tumorigenic potential leads to treatment resistance development. CSCs function through signaling pathways such as the Wnt/β-catenin cascade. While commonly involved in embryogenesis and adult tissues homeostasis, the dysregulation of the Wnt pathway has direct correlations with tumorigenesis, metastasis, and drug resistance. The development of therapies that target CSCs and bulk tumors is both crucial and urgent. However, the extensive crosstalk present between Wnt and other signaling networks (Hedgehog and Notch) complicates the development of efficient long-term therapies with minimal side-effects on normal tissues. Despite the obstacles, the emergence of Wnt inhibitors and subsequent modulation of the signaling pathways would provide dynamic therapeutic approaches to impairing CSCs and reversing resistance mechanisms.

Emerging roles and biomarker potential of WNT6 in human cancers

The WNT6 ligand is a well-known activator of the WNT signaling pathway, considered a vital player in several important physiologic processes during embryonic development and maintaining homeostasis throughout life, regulating the proliferation and differentiation of multiple stem/progenitor cell types. More recently, as it is the case for many key molecular regulators of embryonic development, dysregulation of WNT6 has been implicated in cancer development and progression in multiple studies. In this review, we overview the most significant recent findings regarding WNT6 in the context of human malignancies, exploring its influence on multiple dimensions of tumor pathophysiology and highlighting the putative underlying WNT6-associated molecular mechanisms. We also discuss the potential clinical implications of WNT6 as a prognostic and therapeutic biomarker. This critical review highlights the emerging relevance of WNT6 in multiple human cancers, and its potential as a clinically-useful biomarker, addressing key unanswered questions that could lead to new opportunities in patient diagnosis, stratification, and the development of rationally-designed precision therapies.

Wnt/β-catenin signaling pathway in carcinogenesis and cancer therapy

The Wnt/β-catenin signaling pathway plays a crucial role in various physiological processes, encompassing development, tissue homeostasis, and cell proliferation. Under normal physiological conditions, the Wnt/β-catenin signaling pathway is meticulously regulated. However, aberrant activation of this pathway and downstream target genes can occur due to mutations in key components of the Wnt/β-catenin pathway, epigenetic modifications, and crosstalk with other signaling pathways. Consequently, these dysregulations contribute significantly to tumor initiation and progression. Therapies targeting the Wnt/β-catenin signaling transduction have exhibited promising prospects and potential for tumor treatment. An increasing number of medications targeting this pathway are continuously being developed and validated. This comprehensive review aims to summarize the latest advances in our understanding of the role played by the Wnt/β-catenin signaling pathway in carcinogenesis and targeted therapy, providing valuable insights into acknowledging current opportunities and challenges associated with targeting this signaling pathway in cancer research and treatment.

RSPO2 as Wnt signaling enabler: Important roles in cancer development and therapeutic opportunities

R-spondins are secretory proteins localized in the endoplasmic reticulum and Golgi bodies and are processed through the secretory pathway. Among the R-spondin family, RSPO2 has emanated as a novel regulator of Wnt signaling, which has now been acknowledged in numerous in vitro and in vivo studies. Cancer is an abnormal growth of cells that proliferates and spreads uncontrollably due to the accumulation of genetic and epigenetic factors that constitutively activate Wnt signaling in various types of cancer. Colorectal cancer (CRC) begins when cells in the colon and rectum follow an indefinite pattern of division due to aberrant Wnt activation as one of the key hallmarks. Decades-long progress in research on R-spondins has demonstrated their oncogenic function in distinct cancer types, particularly CRC. As a critical regulator of the Wnt pathway, it modulates several phenotypes of cells, such as cell proliferation, invasion, migration, and cancer stem cell properties. Recently, RSPO mutations, gene rearrangements, fusions, copy number alterations, and altered gene expression have also been identified in a variety of cancers, including CRC. In this review, we addressed the recent updates regarding the recurrently altered R-spondins with special emphasis on the RSPO2 gene and its involvement in potentiating Wnt signaling in CRC. In addition to the compelling physiological and biological roles in cellular fate and regulation, we propose that RSPO2 would be valuable as a potential biomarker for prognostic, diagnostic, and therapeutic use in CRC.

Colorectal cancer: Genetic alterations, novel biomarkers, current therapeutic strategies and clinical trials

Colorectal cancer (CRC) is the third most commonly detected cancer with a serious global health issue. The rates for incidence and mortality for CRC are alarming, especially since the prognosis is abysmal when the CRC is diagnosed at an advanced or metastatic stage. Both type of (modifiable/ non-modifiable) types of risk factors are established for CRC. Despite the advances in recent technology and sophisticated research, the survival rate is still meager due to delays in diagnosis. Therefore, there is urgently required to identify critical biomarkers aiming at early diagnosis and improving effective therapeutic strategies. Additionally, a complete understanding of the dysregulated pathways like PI3K/Akt, Notch, and Wnt associated with CRC progression and metastasis is very beneficial in designing a therapeutic regimen. This review article focused on the dysregulated signaling pathways, genetics and epigenetics alterations, and crucial biomarkers of CRC. This review also provided the list of clinical trials targeting signaling cascades and therapies involving small molecules. This review discusses up-to-date information on novel diagnostic and therapeutic strategies alongside specific clinical trials.

Oncofetal reprogramming in tumor development and progression: novel insights into cancer therapy

Emerging evidence indicates that cancer cells can mimic characteristics of embryonic development, promoting their development and progression. Cancer cells share features with embryonic development, characterized by robust proliferation and differentiation regulated by signaling pathways such as Wnt, Notch, hedgehog, and Hippo signaling. In certain phase, these cells also mimic embryonic diapause and fertilized egg implantation to evade treatments or immune elimination and promote metastasis. Additionally, the upregulation of ATP-binding cassette (ABC) transporters, including multidrug resistance protein 1 (MDR1), multidrug resistance-associated protein 1 (MRP1), and breast cancer-resistant protein (BCRP), in drug-resistant cancer cells, analogous to their role in placental development, may facilitate chemotherapy efflux, further resulting in treatment resistance. In this review, we concentrate on the underlying mechanisms that contribute to tumor development and progression from the perspective of embryonic development, encompassing the dysregulation of developmental signaling pathways, the emergence of dormant cancer cells, immune microenvironment remodeling, and the hyperactivation of ABC transporters. Furthermore, we synthesize and emphasize the connections between cancer hallmarks and embryonic development, offering novel insights for the development of innovative cancer treatment strategies.

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.

Systematic profiling of conditional pathway activation identifies context-dependent synthetic lethalities

The paradigm of cancer-targeted therapies has focused largely on inhibition of critical pathways in cancer. Conversely, conditional activation of signaling pathways as a new source of selective cancer vulnerabilities has not been deeply characterized. In this study, we sought to systematically identify context-specific gene-activation-induced lethalities in cancer. To this end, we developed a method for gain-of-function genetic perturbations simultaneously across ~500 barcoded cancer cell lines. Using this approach, we queried the pan-cancer vulnerability landscape upon activating ten key pathway nodes, revealing selective activation dependencies of MAPK and PI3K pathways associated with specific biomarkers. Notably, we discovered new pathway hyperactivation dependencies in subsets of APC-mutant colorectal cancers where further activation of the WNT pathway by APC knockdown or direct β-catenin overexpression led to robust antitumor effects in xenograft and patient-derived organoid models. Together, this study reveals a new class of conditional gene-activation dependencies in cancer.

Stem Cell Properties of Gastric Cancer Stem-Like Cells under Stress Conditions Are Regulated via the c-Fos/UCH-L3/β-Catenin Axis

Gastric cancer stem-like cells (GCSCs) possess stem cell properties, such as self-renewal and tumorigenicity, which are known to induce high chemoresistance and metastasis. These characteristics of GCSCs are further enhanced by autophagy, worsening the prognosis of patients. Currently, the mechanisms involved in the induction of stemness in GCSCs during autophagy remain unclear. In this study, we compared the cellular responses of GCSCs with those of gastric cancer intestinal cells (GCICs) whose stemness is not induced by autophagy. In response to glucose starvation, the levels of β-catenin and stemness-related genes were upregulated in GCSCs, while the levels of β-catenin declined in GCICs. The pattern of deubiquitinase ubiquitin C-terminal hydrolase-L3 (UCH-L3) expression in GCSCs and GCICs was similar to that of β-catenin expression depending on glucose deprivation. We also observed that inhibition of UCH-L3 activity reduced β-catenin protein levels. The interaction between UCH-L3 and β-catenin proteins was confirmed, and it reduced the ubiquitination of β-catenin. Our results suggest that UCH-L3 induces the stabilization of β-catenin, which is required to promote stemness during autophagy activation. Also, UCH-L3 expression was regulated by c-Fos, and the levels of c-Fos increased in response to autophagy activation. In summary, our findings suggest that the inhibition of UCH-L3 during nutrient deprivation could suppress stress resistance of GCSCs and increase the survival rates of gastric cancer patients.

Targeting Oncogenic Wnt/β-Catenin Signaling in Adrenocortical Carcinoma Disrupts ECM Expression and Impairs Tumor Growth

Adrenocortical carcinoma (ACC) is a rare but highly aggressive cancer with limited treatment options and poor survival for patients with advanced disease. An improved understanding of the transcriptional programs engaged in ACC will help direct rational, targeted therapies. Whereas activating mutations in Wnt/β-catenin signaling are frequently observed, the β-catenin-dependent transcriptional targets that promote tumor progression are poorly understood. To address this question, we analyzed ACC transcriptome data and identified a novel Wnt/β-catenin-associated signature in ACC enriched for the extracellular matrix (ECM) and predictive of poor survival. This suggested an oncogenic role for Wnt/β-catenin in regulating the ACC microenvironment. We further investigated the minor fibrillar collagen, collagen XI alpha 1 (COL11A1), and found that COL11A1 expression originates specifically from cancer cells and is strongly correlated with both Wnt/β-catenin activation and poor patient survival. Inhibition of constitutively active Wnt/β-catenin signaling in the human ACC cell line, NCI-H295R, significantly reduced the expression of COL11A1 and other ECM components and decreased cancer cell viability. To investigate the preclinical potential of Wnt/β-catenin inhibition in the adrenal microenvironment, we developed a minimally invasive orthotopic xenograft model of ACC and demonstrated that treatment with the newly developed Wnt/β-catenin:TBL1 inhibitor Tegavivint significantly reduced tumor growth. Together, our data support that the inhibition of aberrantly active Wnt/β-catenin disrupts transcriptional reprogramming of the microenvironment and reduces ACC growth and survival. Furthermore, this β-catenin-dependent oncogenic program can be therapeutically targeted with a newly developed Wnt/β-catenin inhibitor. These results show promise for the further clinical development of Wnt/β-catenin inhibitors in ACC and unveil a novel Wnt/β-catenin-regulated transcriptome.

Wnt Signaling in Brain Tumors: A Challenging Therapeutic Target

The involvement of Wnt signaling in normal tissue homeostasis and disease has been widely demonstrated over the last 20 years. In particular, dysregulation of Wnt pathway components has been suggested as a relevant hallmark of several neoplastic malignancies, playing a role in cancer onset, progression, and response to treatments. In this review, we summarize the current knowledge on the instructions provided by Wnt signaling during organogenesis and, particularly, brain development. Moreover, we recapitulate the most relevant mechanisms through which aberrant Wnt pathway activation may impact on brain tumorigenesis and brain tumor aggressiveness, with a particular focus on the mutual interdependency existing between Wnt signaling components and the brain tumor microenvironment. Finally, the latest anti-cancer therapeutic approaches employing the specific targeting of Wnt signaling are extensively reviewed and discussed. In conclusion, here we provide evidence that Wnt signaling, due to its pleiotropic involvement in several brain tumor features, may represent a relevant target in this context, although additional efforts will be needed to: (i) demonstrate the real clinical impact of Wnt inhibition in these tumors; (ii) overcome some still unsolved concerns about the potential systemic effects of such approaches; (iii) achieve efficient brain penetration.

Role of β-Catenin Activation in the Tumor Immune Microenvironment and Immunotherapy of Hepatocellular Carcinoma

Recently, the therapeutic combination of atezolizumab and bevacizumab was widely used to treat advanced hepatocellular carcinoma (HCC). According to recent clinical trials, immune checkpoint inhibitors (ICIs) and molecular target agents are expected to be key therapeutic strategies in the future. Nonetheless, the mechanisms underlying molecular immune responses and immune evasion remain unclear. The tumor immune microenvironment plays a vital role in HCC progression. The infiltration of CD8-positive cells into tumors and the expression of immune checkpoint molecules are key factors in this immune microenvironment. Specifically, Wnt/β catenin pathway activation causes "immune exclusion", associated with poor infiltration of CD8-positive cells. Some clinical studies suggested an association between ICI resistance and β-catenin activation in HCC. Additionally, several subclassifications of the tumor immune microenvironment were proposed. The HCC immune microenvironment can be broadly divided into inflamed class and non-inflamed class, with several subclasses. β-catenin mutations are important factors in immune subclasses; this may be useful when considering therapeutic strategies as β-catenin activation may serve as a biomarker for ICI. Various types of β-catenin modulators were developed. Several kinases may also be involved in the β-catenin pathway. Therefore, combinations of β-catenin modulators, kinase inhibitors, and ICIs may exert synergistic effects.

The Relationship between LRP6 and Wnt/β-Catenin Pathway in Colorectal and Esophageal Cancer

High expression of low-density lipoprotein receptor-related protein 6 (LRP6), a key component of the Wnt/β-catenin signaling pathway, is reported to be associated with malignant potential in some solid tumors including breast cancer and hepatocellular carcinoma. Few reports, however, have examined its function and clinical significance in colorectal cancers (CRC) demonstrating constitutive activation of Wnt signaling. Here, we compared the expression level and function of LRP6 in CRC with that of esophageal squamous cell carcinoma (ESCC) bearing few Wnt/β-catenin pathway mutations. On immunohistochemical staining, high LRP6 expression was noted in three of 68 cases (4.4%), and high β-catenin in 38 of 67 cases (56.7%) of CRC. High LRP6 expression was found in 21 of 82 cases (25.6%), and high β-catenin expression in 29 of 73 cases (39.7%) of ESCC. In our in vitro studies, LRP6 knockdown hardly changed Wnt signaling activity in CRC cell lines with mutations in Wnt signaling downstream genes. In contrast, in ESCC cell lines without Wnt signaling-related mutations, LRP6 knockdown significantly decreased Wnt signaling activity. LRP6 function may depend on constitutive activation of Wnt signaling.

Cancer-Specific Delivery of Proteolysis-Targeting Chimeras (PROTACs) and Their Application to Cancer Immunotherapy

Proteolysis-targeting chimeras (PROTACs) are rapidly emerging as a potential therapeutic strategy for cancer therapy by inducing the degradation of tumor-overexpressing oncogenic proteins. They can specifically catalyze the degradation of target oncogenic proteins by recruiting E3 ligases and utilizing the ubiquitin-proteasome pathway. Since their mode of action is universal, irreversible, recyclable, long-lasting, and applicable to 'undruggable' proteins, PROTACs are gradually replacing the role of conventional small molecular inhibitors. Moreover, their application areas are being expanded to cancer immunotherapy as various types of oncogenic proteins that are involved in immunosuppressive tumor microenvironments. However, poor water solubility and low cell permeability considerably restrict the pharmacokinetic (PK) property, which necessitates the use of appropriate delivery systems for cancer immunotherapy. In this review, the general characteristics, developmental status, and PK of PROTACs are first briefly covered. Next, recent studies on the application of various types of passive or active targeting delivery systems for PROTACs are introduced, and their effects on the PK and tumor-targeting ability of PROTACs are described. Finally, recent drug delivery systems of PROTACs for cancer immunotherapy are summarized. The adoption of an adequate delivery system for PROTAC is expected to accelerate the clinical translation of PROTACs, as well as improve its efficacy for cancer therapy.

Medicinal Chemistry Strategies for the Development of Inhibitors Disrupting β-Catenin's Interactions with Its Nuclear Partners

Dysregulation of the Wnt/β-catenin signaling pathway is strongly associated with various aspects of cancer, including tumor initiation, proliferation, and metastasis as well as antitumor immunity, and presents a promising opportunity for cancer therapy. Wnt/β-catenin signaling activation increases nuclear dephosphorylated β-catenin levels, resulting in β-catenin binding to TCF and additional cotranscription factors, such as BCL9, CBP, and p300. Therefore, directly disrupting β-catenin's interactions with these nuclear partners holds promise for the effective and selective suppression of the aberrant activation of Wnt/β-catenin signaling. Herein, we summarize recent advances in biochemical techniques and medicinal chemistry strategies used to identify potent peptide-based and small-molecule inhibitors that directly disrupt β-catenin's interactions with its nuclear binding partners. We discuss the challenges involved in developing drug-like inhibitors that target the interactions of β-catenin and its nuclear binding partner into therapeutic agents.

PCLassoLog: A protein complex-based, group Lasso-logistic model for cancer classification and risk protein complex discovery

Risk gene identification has attracted much attention in the past two decades. Since most genes need to be translated into proteins and cooperate with other proteins to form protein complexes to carry out cellular functions, which significantly extends the functional diversity of individual proteins, revealing the molecular mechanism of cancer from a comprehensive perspective needs to shift from identifying individual risk genes toward identifying risk protein complexes. Here, we embed protein complexes into the regularized learning framework and propose a protein complex-based, group Lasso-logistic model (PCLassoLog) to discover risk protein complexes. Experiments on deep proteomic data of two cancer types show that PCLassoLog yields superior predictive performance on independent datasets. More importantly, PCLassoLog identifies risk protein complexes that not only contain individual risk proteins but also incorporate close partners that synergize with them. Furthermore, selection probabilities are calculated and two other protein complex-based models are proposed to complement PCLassoLog in identifying reliable risk protein complexes. Based on PCLassoLog, a pan-cancer analysis is performed to identify risk protein complexes in 12 cancer types. Finally, PCLassoLog is used to discover risk protein complexes associated with gene mutation. We implement all protein complex-based models as an R package PCLassoReg, which may serve as an effective tool to discover risk protein complexes in various contexts.

Wnt Signaling in the Development of Bone Metastasis

Wnt signaling occurs through evolutionarily conserved pathways that affect cellular proliferation and fate decisions during development and tissue maintenance. Alterations in these highly regulated pathways, however, play pivotal roles in various malignancies, promoting cancer initiation, growth and metastasis and the development of drug resistance. The ability of cancer cells to metastasize is the primary cause of cancer mortality. Bone is one of the most frequent sites of metastases that generally arise from breast, prostate, lung, melanoma or kidney cancer. Upon their arrival to the bone, cancer cells can enter a long-term dormancy period, from which they can be reactivated, but can rarely be cured. The activation of Wnt signaling during the bone metastasis process was found to enhance proliferation, induce the epithelial-to-mesenchymal transition, promote the modulation of the extracellular matrix, enhance angiogenesis and immune tolerance and metastasize and thrive in the bone. Due to the complexity of Wnt pathways and of the landscape of this mineralized tissue, Wnt function during metastatic progression within bone is not yet fully understood. Therefore, we believe that a better understanding of these pathways and their roles in the development of bone metastasis could improve our understanding of the disease and may constitute fertile ground for potential therapeutics.

Response to BRAF-targeted Therapy Is Enhanced by Cotargeting VEGFRs or WNT/β-Catenin Signaling in BRAF-mutant Colorectal Cancer Models

The fact that 10% of colorectal cancer tumors harbor BRAF V600E mutations suggested targeting BRAF as a potential therapy. However, BRAF inhibitors have only limited single-agent efficacy in this context. The potential for combination therapy has been shown by the BEACON trial where targeting the EGF receptor with cetuximab greatly increased efficacy of BRAF inhibitors in BRAF-mutant colorectal cancer. Therefore, we explored whether efficacy of the mutant BRAF inhibitor vemurafenib could be enhanced by cotargeting of either oncogenic WNT/β-catenin signaling or VEGFR signaling. We find the WNT/β-catenin inhibitors pyrvinium, ICG-001 and PKF118-310 attenuate growth of colorectal cancer cell lines in vitro with BRAF-mutant lines being relatively more sensitive. Pyrvinium combined with vemurafenib additively or synergistically attenuated growth of colorectal cancer cell lines in vitro. The selective and potent VEGFR inhibitor axitinib was most effective against BRAF-mutant colorectal cancer cell lines in vitro, but the addition of vemurafenib did not significantly increase these effects. When tested in vivo in animal tumor models, both pyrvinium and axitinib were able to significantly increase the ability of vemurafenib to attenuate tumor growth in xenografts of BRAF-mutant colorectal cancer cells. The magnitude of these effects was comparable with that induced by a combination of vemurafenib and cetuximab. This was associated with additive effects on release from tumor cells and tumor microenvironment cell types of substances that would normally aid tumor progression. Taken together, these preclinical data indicate that the efficacy of BRAF inhibitor therapy in colorectal cancer could be increased by cotargeting either WNT/β-catenin or VEGFRs with small-molecule inhibitors.

Emerging Direct Targeting β-Catenin Agents

Aberrant accumulation of β-catenin in the cell nucleus as a result of deregulation of the Wnt/β-catenin pathway is found in various types of cancer. Direct β-catenin targeting agents are being researched despite obstacles; however, specific β-catenin drugs for clinical treatments have not been approved so far. We focused on direct β-catenin targeting of potential therapeutic value as anticancer agents. This review provides recent advances on small molecule β-catenin agents. Structure-activity relationships and biological activities of reported inhibitors are discussed. This work provides useful knowledge in the discovery of β-catenin agents.

Wnt/β-Catenin Signaling as a Driver of Stemness and Metabolic Reprogramming in Hepatocellular Carcinoma

Simple Summary

Aberrant Wnt/β-catenin signaling has been reported to play crucial role in pathogenesis of hepatocellular carcinoma (HCC). In this review, we focus on the regulatory role of Wnt/β-catenin signaling in cancer stemness and metabolic reprogramming, which are two emerging hallmarks of cancer. Understanding the role of Wnt/β-catenin signaling in regulation of the above processes reveals novel therapeutic strategy against this deadly disease.

Abstract

Hepatocellular carcinoma (HCC) is a major cause of cancer death worldwide due to its high rates of tumor recurrence and metastasis. Aberrant Wnt/β-catenin signaling has been shown to play a significant role in HCC development, progression and clinical impact on tumor behavior. Accumulating evidence has revealed the critical involvement of Wnt/β-catenin signaling in driving cancer stemness and metabolic reprogramming, which are regarded as emerging cancer hallmarks. In this review, we summarize the regulatory mechanism of Wnt/β-catenin signaling and its role in HCC. Furthermore, we provide an update on the regulatory roles of Wnt/β-catenin signaling in metabolic reprogramming, cancer stemness and drug resistance in HCC. We also provide an update on preclinical and clinical studies targeting Wnt/β-catenin signaling alone or in combination with current therapies for effective cancer therapy. This review provides insights into the current opportunities and challenges of targeting this signaling pathway in HCC.

Stabilizing and upregulating Axin with tankyrase inhibitor reverses 5-fluorouracil chemoresistance and proliferation by targeting the WNT/caveolin-1 axis in colorectal cancer cells

Chemoresistance is a main obstacle for colorectal cancer treatment. In this study, we evaluated the effects and mechanisms of the WNT/β-catenin signaling pathway on the chemoresistance of SW480 and SW620 colorectal cancer cells. The activity of β-catenin was activated/inhibited by the small molecule compound GSK-3 inhibitor 6-bromo-indirubin-3'-oxime and the tankyrase inhibitor XAV939. The downstream target genes of the WNT/β-catenin signaling pathway were screened using a cDNA microarray and bioinformatics analysis. Apoptosis induced by 5-Fu, cell cycle distribution and expression levels of WNT/β-catenin/TCF12/caveolin-1 and multidrug resistance proteins were examed by flow cytometry and western blot after β-catenin activation/inhibition and caveolin-1 overexpression/interference. The effect and mechanism of XAV939 on proliferation and apoptosis induced by 5-Fu in xenograft tumors of nude mice were evaluated by immunohistochemistry and TUNEL staining. 6-Bromo-indirubin-3'-oxime treatment increased β-catenin expression by regulating GSK-3β phosphorylation, accompanied by upregulation of TCF12, caveolin-1, P-gp, and MRP2 and downregulation of apoptosis induced by 5-Fu. Conversely, XAV939 treatment decreased β-catenin expression by upregulating Axin, accompanied by downregulation of TCF12, Caveolin-1, P-gp, and MRP2 and upregulation of apoptosis induced by 5-Fu. The caveolin-1 gene was identified as an important downstream gene of the WNT/β-catenin signaling pathway. Caveolin-1 overexpression upregulated β-catenin expression, increased P-gp and MRP2 expression and decreased apoptosis induced by 5-Fu; conversely, caveolin-1 interference caused the opposite effects. In addition, in vivo experiments showed that XAV939 treatment reduced β-catenin expression, increased apoptosis induced by 5-Fu and repressed xenograft tumor growth. Our findings suggested that inhibition of WNT/β-catenin/TCF12/caveolin-1 provides a new promising therapeutic strategy for colorectal cancer treatment.

Targeting the interaction of β-catenin and TCF/LEF transcription factors to inhibit oncogenic Wnt signaling

The Wnt/β-catenin signaling pathway is crucially involved in embryonic development, stem cell maintenance and tissue renewal. Hyperactivation of this pathway is associated with the development and progression of various types of cancers. The transcriptional coactivator β-catenin represents a pivotal component of the pathway and its interaction with transcription factors of the TCF/LEF family is central to pathway activation. Inhibition of this crucial protein-protein interaction via direct targeting of β-catenin is considered a promising strategy for the inactivation of oncogenic Wnt signaling. This review summarizes advances in the development of Wnt antagonists that have been shown to directly bind β-catenin.

What we have learnt from Drosophila model organism: the coordination between insulin signaling pathway and tumor cells

Cancer development is related to a variety of signaling pathways which mediate various cellular processes including growth, survival, division and competition of cells, as well as cell-cell interaction. The insulin signaling pathway interacts with different pathways and plays a core role in the regulations of all these processes. In this study, we reviewed recent studies on the relationship between the insulin signaling pathway and tumors using the Drosophila melanogaster model. We found that on one hand, the insulin pathway is normally hyperactive in tumor cells, which promotes tumor growth, and on the other hand, tumor cells can suppress the growth of healthy tissues via inhibition of their insulin pathway. Moreover, systematic disruption in glucose homeostasis also facilitates cancer development by different mechanisms. The studies on how the insulin network regulates the behaviors of cancer cells may help to discover new therapeutic treatments for cancer.

Signaling pathways and their potential therapeutic utility in esophageal squamous cell carcinoma

Esophageal cancer is a complex gastrointestinal malignancy with an extremely poor outcome. Approximately 80% of cases of this malignancy in Asian countries including India are of squamous cell origin, termed Esophageal Squamous Cell Carcinoma (ESCC).The five-year survival rate in ESCC patients is less than 20%. Neo-adjuvant chemo-radiotherapy (NACRT) followed by surgical resection remains the major therapeutic strategy for patients with operable ESCC. However, resistance to NACRT and local recurrence after initial treatment are the leading cause of dismal outcomes in these patients. Therefore, an alternative strategy to promote response to the therapy and reduce the post-operative disease recurrence is highly needed. At the molecular level, wide variations have been observed in tumor characteristics among different populations, nevertheless, several common molecular features have been identified which orchestrate disease progression and clinical outcome in the malignancy. Therefore, determination of candidate molecular pathways for targeted therapy remains the mainstream idea of focus in ESCC research. In this review, we have discussed the key signaling pathways associated with ESCC, i.e., Notch, Wnt, and Nrf2 pathways, and their crosstalk during disease progression. We further discuss the recent developments of novel agents to target these pathways in the context of targeted cancer therapy. In-depth research of the signaling pathways, gene signatures, and a combinatorial approach may help in discovering targeted therapy for ESCC.

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.

A novel β-catenin/BCL9 complex inhibitor blocks oncogenic Wnt signaling and disrupts cholesterol homeostasis in colorectal cancer

Dysregulated Wnt/β-catenin signaling is implicated in the pathogenesis of many human cancers, including colorectal cancer (CRC), making it an attractive clinical target. With the aim of inhibiting oncogenic Wnt activity, we developed a high-throughput screening AlphaScreen assay to identify selective small-molecule inhibitors of the interaction between β-catenin and its coactivator BCL9. We identified a compound that consistently bound to β-catenin and specifically inhibited in vivo native β-catenin/BCL9 complex formation in CRC cell lines. This compound inhibited Wnt activity, down-regulated expression of the Wnt/β-catenin signature in gene expression studies, disrupted cholesterol homeostasis, and significantly reduced the proliferation of CRC cell lines and tumor growth in a xenograft mouse model of CRC. This study has therefore identified a specific small-molecule inhibitor of oncogenic Wnt signaling, which may have value as a probe for functional studies and has important implications for the development of novel therapies in patients with CRC.

Current Approaches in Hepatoblastoma-New Biological Insights to Inform Therapy

PURPOSE OF REVIEW

As the most common pediatric primary liver cancer with rising incidence, hepatoblastoma remains challenging to treat. Here, we review the current understanding of the biology of hepatoblastoma and discuss how recent advances may lead to new treatment modalities.

RECENT FINDINGS

Standard chemotherapy regimens including cisplatin, in addition to surgery, have led to high cure rates among patients with low stage hepatoblastoma; however, metastatic and relapsed disease continue to have poor outcomes. Recent genomics and functional studies in cell lines and mouse models have established a central role for the Wnt/β-catenin pathway in tumorigenesis. Targeted agents and immunotherapy approaches are emerging as potential treatment avenues. With recent gains in knowledge of the genomic and transcriptomic landscape of hepatoblastoma, new therapeutic mechanisms can now be explored to improve outcomes for metastatic and relapsed hepatoblastoma and to reduce the toxicity of current treatments.

Abrogating the Interaction Between p53 and Mortalin (Grp75/HSPA9/mtHsp70) for Cancer Therapy: The Story so far

p53 is a transcription factor that activates the expression of a set of genes that serve as a critical barrier to oncogenesis. Inactivation of p53 is the most common characteristic in sporadic human cancers. Mortalin is a differentially sub-cellularly localized member of the heat shock protein 70 family of chaperones that has essential mitochondrial and extra-mitochondrial functions. Elevated mortalin levels in multiple cancerous tissues and tumor-derived cell lines emphasized its key role in oncogenesis. One of mortalin’s major oncogenic roles is the inactivation of p53. Mortalin binds to p53 sequestering it in the cytoplasm. Hence, p53 cannot freely shuttle to the nucleus to perform its tumor suppressor functions as a transcription factor. This protein-protein interaction was reported to be cancer-specific, hence, a selective druggable target for a rationalistic cancer therapeutic strategy. In this review article, the chronological identification of mortalin-p53 interactions is summarized, the challenges and general strategies for targeting protein-protein interactions are briefly discussed, and information about compounds that have been reported to abrogate mortalin-p53 interaction is provided. Finally, the reasons why the disruption of this druggable interaction has not yet been applied clinically are discussed.

β-Catenin signaling in hepatocellular carcinoma

Deregulated Wnt/β-catenin signaling is one of the main genetic alterations in human hepatocellular carcinoma (HCC). Comprehensive genomic analyses have revealed that gain-of-function mutation of CTNNB1, which encodes β-catenin, and loss-of-function mutation of AXIN1 occur in approximately 35% of human HCC samples. Human HCCs with activation of the Wnt/β-catenin pathway demonstrate unique gene expression patterns and pathological features. Activated Wnt/β-catenin synergizes with multiple signaling cascades to drive HCC formation, and it functions through its downstream effectors. Therefore, strategies targeting Wnt/β-catenin have been pursued as possible therapeutics against HCC. Here, we review the genetic alterations and oncogenic roles of aberrant Wnt/β-catenin signaling during hepatocarcinogenesis. In addition, we discuss the implication of this pathway in HCC diagnosis, classification, and personalized treatment.

Wnt/β-catenin signalling: function, biological mechanisms, and therapeutic opportunities

The Wnt/β-catenin pathway comprises a family of proteins that play critical roles in embryonic development and adult tissue homeostasis. The deregulation of Wnt/β-catenin signalling often leads to various serious diseases, including cancer and non-cancer diseases. Although many articles have reviewed Wnt/β-catenin from various aspects, a systematic review encompassing the origin, composition, function, and clinical trials of the Wnt/β-catenin signalling pathway in tumour and diseases is lacking. In this article, we comprehensively review the Wnt/β-catenin pathway from the above five aspects in combination with the latest research. Finally, we propose challenges and opportunities for the development of small-molecular compounds targeting the Wnt signalling pathway in disease treatment.

Targeted β-catenin ubiquitination and degradation by multifunctional stapled peptides

Aberrant activation of the Wnt signaling pathway has been identified in numerous types of cancer. One common feature of oncogenic Wnt regulation involves an increase in the cellular levels of β-catenin due to interference with its constitutive ubiquitin-dependent degradation. Targeting β-catenin has therefore emerged as an appealing approach for the treatment of Wnt-dependent cancers. Here, we report a strategy that employs multifunctional stapled peptides to recruit an E3 ubiquitin ligase to β-catenin, thereby rescuing β-catenin degradation by hijacking the endogenous ubiquitin-proteasome pathway. Specifically, we designed, synthesized, and evaluated a panel of multifunctional stapled peptides that have a β-catenin binding moiety (StAx-35) covalently linked to a second stapled peptide moiety (SAH-p53-8), which is capable to interact with the E3 ubiquitin ligase MDM2. We found that in vitro these multifunctional peptides can recruit the MDM2 protein to β-catenin and induce poly-ubiquitination on β-catenin. In cellulo, treatment of the human colorectal cancer cell line SW480 with the multifunctional stapled peptides showed dose-dependent degradation of endogenous β-catenin levels. In addition, a luciferase reporter assay showed that the multifunctional stapled peptides can suppress β-catenin-mediated gene expression via the Wnt signaling pathway. Therefore, these multifunctional stapled peptides provide a unique research tool for examining the Wnt signaling pathway by targeted knockdown of β-catenin at the protein level, and may serve as leads for potential drug candidates in the treatment of Wnt-dependent cancers.

Drug discovery efforts toward inhibitors of canonical Wnt/β-catenin signaling pathway in the treatment of cancer: A composition-of-matter review (2010-2020)

The Wnt/β-catenin pathway has a crucial role in the proliferation and differentiation of normal cells as well as the self-renewal and pluripotency of stem cells, including cancer stem cells (CSCs). Targeting this pathway with small-molecule chemotherapeutics, discovered via conventional efforts, has proved difficult. Recently, computer-aided drug discovery efforts have produced promising chemotherapeutics. A concerted effort to develop inhibitors of this pathway through more efficient and cost-effective drug discovery methods could lead to a significant increase in clinically relevant therapeutics. Herein, patents from 2010 to 2020 are reviewed to identify those that have disclosed composition of matter for small-molecule inhibitors of the Wnt/ β-catenin pathway for cancer. We believe that such efforts will provide insights for future therapeutic candidate discovery and development in this field.

Epigenetic Regulation of the Wnt/β-Catenin Signaling Pathway in Cancer

Studies over the past four decades have elucidated the role of Wnt/β-catenin mediated regulation in cell proliferation, differentiation and migration. These processes are fundamental to embryonic development, regeneration potential of tissues, as well as cancer initiation and progression. In this review, we focus on the epigenetic players which influence the Wnt/β-catenin pathway via modulation of its components and coordinated regulation of the Wnt target genes. The role played by crosstalk with other signaling pathways mediating tumorigenesis is also elaborated. The Hippo/YAP pathway is particularly emphasized due to its extensive crosstalk via the Wnt destruction complex. Further, we highlight the recent advances in developing potential therapeutic interventions targeting the epigenetic machinery based on the characterization of these regulatory networks for effective treatment of various cancers and also for regenerative therapies.

The Wnt signaling pathway in tumorigenesis, pharmacological targets, and drug development for cancer therapy

Wnt signaling was initially recognized to be vital for tissue development and homeostasis maintenance. Further studies revealed that this pathway is also important for tumorigenesis and progression. Abnormal expression of signaling components through gene mutation or epigenetic regulation is closely associated with tumor progression and poor prognosis in several tissues. Additionally, Wnt signaling also influences the tumor microenvironment and immune response. Some strategies and drugs have been proposed to target this pathway, such as blocking receptors/ligands, targeting intracellular molecules, beta-catenin/TCF4 complex and its downstream target genes, or tumor microenvironment and immune response. Here we discuss the roles of these components in Wnt signaling pathway in tumorigenesis and cancer progression, the underlying mechanisms that is responsible for the activation of Wnt signaling, and a series of drugs targeting the Wnt pathway provide multiple therapeutic values. Although some of these drugs exhibit exciting anti-cancer effect, clinical trials and systematic evaluation should be strictly performed along with multiple-omics technology.

C644-0303, a small-molecule inhibitor of the Wnt/β-catenin pathway, suppresses colorectal cancer growth

The Wnt/β‐catenin signaling pathway plays an important role in tissue homeostasis, and its malignant activation is closely related to the occurrence and development of many cancers, especially colorectal cancer with adenomatous polyposis coli (APC) and CTNNB1 mutations. By applying a TCF/lymphoid‐enhancing factor (LEF) luciferase reporter system, the high‐throughput screening of 18 840 small‐molecule compounds was performed. A novel scaffold compound, C644‐0303, was identified as a Wnt/β‐catenin signaling inhibitor and exhibited antitumor efficacy. It inhibited both constitutive and ligand activated Wnt signals and its downstream gene expression. Functional studies showed that C644‐0303 causes cell cycle arrest, induces apoptosis, and inhibits cancer cell migration. Moreover, transcription factor array indicated that C644‐0303 could suppress various tumor‐promoting transcription factor activities in addition to Wnt/β‐catenin. Finally, C644‐0303 suppressed tumor spheroidization in a 3‐dimensional cell culture model and inhibited xenograft tumor growth in mice. In conclusion, we report a novel structural small molecular inhibitor targeting the Wnt/β‐catenin signaling pathway that has therapeutic potential for colorectal cancer treatment.

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.

Deregulation of signaling pathways controlling cell survival and proliferation in cancer cells alters induction of cytochrome P450 family 1 enzymes

Cytochrome P450 family 1 (CYP1) enzymes contribute both to metabolism of xenobiotics and to the control of endogenous levels of ligands of the aryl hydrocarbon receptor (AhR). Their activities, similar to other CYPs, can be altered in tumor tissues. Here, we examined a possible role of proliferative/survival pathways signaling, which is often deregulated in tumor cells, and possible links with p300 histone acetyltransferase (a transcriptional co-activator) in the control of CYP1 expression, focusing particularly on CYP1A1. Using cell models derived from human liver, we observed that the induction of CYP1A1 expression, as well as other CYP1 enzymes, was reduced in exponentially growing cells, as compared with their non-dividing counterparts. The siRNA-mediated inhibition of proliferation/pro-survival signaling pathway effectors (such as β-catenin and/or Hippo pathway effectors YAP/TAZ) increased the AhR ligand-induced CYP1A1 mRNA levels in liver HepaRG cells, and/or in colon carcinoma HCT-116 cells. The activation of proliferative Wnt/β-catenin signaling in HCT-116 cells reduced both the induction of CYP1 enzymes and the binding of p300 to the promoter of CYP1A1 or CYP1B1 genes. These results seem to indicate that aberrant proliferative signaling in tumor cells could suppress induction of CYP1A1 (or other CYP1 enzymes) via competition for p300 binding. This mechanism could be involved in modulation of the metabolism of both endogenous and exogenous substrates of CYP1A1 (and other CYP1 enzymes), with possible further consequences for alterations of the AhR signaling in tumor cells, or additional functional roles of CYP1 enzymes.

Wnt signaling activation: targets and therapeutic opportunities for stem cell therapy and regenerative medicine

Wnt proteins are secreted morphogens that play critical roles in embryonic development, stem cell proliferation, self-renewal, tissue regeneration and remodeling in adults. While aberrant Wnt signaling contributes to diseases such as cancer, activation of Wnt/β-catenin signaling is a target of interest in stem cell therapy and regenerative medicine. Recent high throughput screenings from chemical and biological libraries, combined with improved gene expression reporter assays of Wnt/β-catenin activation together with rational drug design, led to the development of a myriad of Wnt activators, with different mechanisms of actions. Among them, Wnt mimics, antibodies targeting Wnt inhibitors, glycogen-synthase-3β inhibitors, and indirubins and other natural product derivatives are emerging modalities to treat bone, neurodegenerative, eye, and metabolic disorders, as well as prevent ageing. Nevertheless, the creation of Wnt-based therapies has been hampered by challenges in developing potent and selective Wnt activators without off-target effects, such as oncogenesis. On the other hand, to avoid these risks, their use to promote ex vivo expansion during tissue engineering is a promising application.