Wnt Signaling: Paths for Cancer Progression

Wnt-Independent SARS-CoV-2 Infection in Pulmonary Epithelial Cells

The Wnt signaling pathway within host cells regulates infections by several pathogenic bacteria and viruses. Recent studies suggested that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection depends on β-catenin and can be inhibited by the antileprotic drug clofazimine. Since clofazimine has been identified by us as a specific inhibitor of Wnt/β-catenin signaling, these works could indicate a potential role of the Wnt pathway in SARS-CoV-2 infection. Here, we show that the Wnt pathway is active in pulmonary epithelial cells. However, we find that in multiple assays, SARS-CoV-2 infection is insensitive to Wnt inhibitors, including clofazimine, acting at different levels within the pathway. Our findings assert that endogenous Wnt signaling in the lung is unlikely required or involved in the SARS-CoV-2 infection and that pharmacological inhibition of this pathway with clofazimine or other compounds is not a universal way to develop treatments against the SARS-CoV-2 infection. IMPORTANCE The development of inhibitors of the SARS-CoV-2 infection remains a need of utmost importance. The Wnt signaling pathway in host cells is often implicated in infections by bacteria and viruses. In this work, we show that, despite previous indications, pharmacological modulation of the Wnt pathway does not represent a promising strategy to control SARS-CoV-2 infection in lung epithelia.

KISS1 metastasis suppressor in tumor dormancy: a potential therapeutic target for metastatic cancers?

Present therapeutic approaches do not effectively target metastatic cancers, often limited by their inability to eliminate already-seeded non-proliferative, growth-arrested, or therapy-resistant tumor cells. Devising effective approaches targeting dormant tumor cells has been a focus of cancer clinicians for decades. However, progress has been limited due to limited understanding of the tumor dormancy process. Studies on tumor dormancy have picked up pace and have resulted in the identification of several regulators. This review focuses on KISS1, a metastasis suppressor gene that suppresses metastasis by keeping tumor cells in a state of dormancy at ectopic sites. The review explores mechanistic insights of KISS1 and discusses its potential application as a therapeutic against metastatic cancers by eliminating quiescent cells or inducing long-term dormancy in tumor cells.

Matrine restrains the development of colorectal cancer through regulating the AGRN/Wnt/β-catenin pathway

BACKGROUND

Colorectal cancer is a common malignant digestive tract tumor. This study aimed to explore the biological role and potential underlying mechanism of matrine in colorectal cancer.

METHODS

The mRNA expression of AGRN was measured using RT-qPCR. Cell proliferation, migration, invasion and apoptosis were determined using CCK-8, EdU, transwell assays and flow cytometry, respectively. Xenograft tumor experiment was performed to explore the action of matrine and AGRN on tumor growth in colorectal cancer in vivo. Immunohistochemistry (IHC) assay was applied for AGRN, β-catenin, and c-Myc expression in the tumor tissues from mice.

RESULTS

Matrine dramatically repressed cell growth and reduced the level of AGRN in colorectal cancer cells. AGRN expression was boosted colorectal cancer tissues and cells. AGRN downregulation depressed cell proliferation, migration, invasion, and enhanced cell apoptosis in colorectal cancer cells. Moreover, matrine showed the anti-tumor effects on colorectal cancer cells via regulating AGRN expression. AGRN knockdown could inactivate the Wnt/β-catenin pathway in colorectal cancer cells. We found that AGRN downregulation exhibited the inhibition action in the progression of colorectal cancer by modulating the Wnt/β-catenin pathway. In addition, matrine could inhibit the activation of the Wnt/β-catenin pathway through regulating AGRN in colorectal cancer cells. Furthermore, xenograft tumor experiment revealed that matrine treatment or AGRN knockdown repressed the development of colorectal cancer via the Wnt/β-catenin pathway in vivo.

CONCLUSION

Matrine retarded colorectal cancer development by modulating AGRN to inactivate the Wnt/β-catenin pathway.

miR-4757-3p Inhibited the Migration and Invasion of Lung Cancer Cell via Targeting Wnt Signaling Pathway

Lung cancer accounts for the vast majority of cancer-related deaths worldwide, and aberrant miRNA expression is commonly observed as the disease progresses. The current study aimed to determine the role of miR-4757-3p in the development of lung cancer. The real-time PCR test was performed to determine the expression of miR-4757-3p in lung cancer cell lines. miR-4757-3p was downregulated in A549 cells. CCK8 and transwell assays demonstrated that overexpression of miR-4757-3p significantly reduced A549 cell invasion and migration. Bioinformatic analysis by the TargetScan database predicted the possible targets of miR-4757-3p. A luciferase activity test was used to determine the direct relationship between miR-4757-3p, Wnt5a, and Wnt8b. The overexpression of miR-4757-3p drastically inhibited the expression of Wnt5a and Wnt8b. Furthermore, we discovered that silencing Wnt5a and Wnt8b significantly lowered β-catenin expression and hampered invasion and migration. Finally, miR-4757-3p inhibited lung cancer cell migration and invasion by inhibiting the activation of the Wnt signaling pathway. Our study provided evidence that miR-4757-3p could be developed as an indicator or an anticancer target in the clinical application.

Integrated analysis of necroptosis-related genes for evaluating immune infiltration and colon cancer prognosis

Background

Colon cancer (CC) is the second most common gastrointestinal malignancy. About one in five patients have already developed distant metastases at the time of initial diagnosis, and up to half of patients develop distant metastases from initial local disease, which leads to a poor prognosis for CC patients. Necroptosis plays a key role in promoting tumor growth in different tumors. The purpose of this study was to construct a prognostic model composed of necroptosis-related genes (NRGs) in CC.

Methods

The Cancer Genome Atlas was used to obtain information on clinical features and gene expression. Gene expression differential analysis, weighted gene co-expression network analysis, univariate Cox regression analysis and the least absolute shrinkage and selection operator regression algorithm were utilized to identify prognostic NRGs. Thereafter, a risk scoring model was established based on the NRGs. Biological processes and pathways were identified by gene ontology and gene set enrichment analysis (GSEA). Further, protein-protein interaction and ceRNA networks were constructed based on mRNA-miRNA-lncRNA. Finally, the effect of necroptosis related risk score on different degrees of immune cell infiltration was evaluated.

Results

CALB1, CHST13, and SLC4A4 were identified as NRGs of prognostic significance and were used to establish a risk scoring model. The time-dependent receiver operating characteristic curve analysis revealed that the model could well predict the 1-, 3-, and 5-year overall survival (OS). Further, GSEA suggested that the NRGs may participate in biological processes, such as the WNT pathway and JAK-Stat pathway. Eight key hub genes were identified, and a ceRNA regulatory network, which comprised 1 lncRNA, 5 miRNAs and 3 mRNAs, was constructed. Immune infiltration analysis revealed that the low-risk group had significantly higher immune-related scores than the high-risk group. A nomogram of the model was constructed based on the risk score, necroptosis, and the clinicopathological features (age and TNM stage). The calibration curves implied that the model was effective at predicting the 1-, 3-, and 5-year OS of CC.

Conclusion

Our NRG-based prognostic model can assist in the evaluation of CC prognosis and the identification of therapeutic targets for CC.

ERO1L promotes the proliferation and metastasis of lung adenocarcinoma via the Wnt2/β-catenin signaling pathway

PURPOSE

This study aimed to explore the role and underlying mechanism of action of Endoplasmic reticulum oxidoreductin-1 L (ERO1L) in lung adenocarcinoma (LUAD).

MATERIALS AND METHODS

The Gene expression profiling interactive analysis database was used to analyze the expression of ERO1L in LUAD cases. The expression of ERO1L and Wnt2 in LUAD tissue was evaluated using immunohistochemistry. We also used western blotting to assess the expression of ERO1L or Wnt2 and the phosphorylation of β-catenin in LUAD cell lines. Plasmid transfection and small interfering RNA were used for overexpression and knockdown of ERO1L in LUAD cells, respectively. The proliferation, invasion and migration of LUAD cells were analyzed using cell viability, Transwell invasion and wound healing assays. The growth of LUAD tumors in animal models was assessed using tumor xenograft experiments.

RESULTS

This study revealed that elevated ERO1L expression was associated with a poor prognosis in LUAD patients. In addition, ERO1L expression was significantly associated with lymph-node metastasis, TNM stage and tumor size. The expression of Wnt2 was positively associated with ERO1L expression in LUAD tissue samples and cell lines. ERO1L overexpression upregulated the expression of Wnt2 and β-catenin phosphorylation in vitro. Additionally, ERO1L was essential for the ubiquitination of Wnt2. Last, ERO1L promoted the proliferation and metastasis of LUAD via the Wnt2 signaling pathway in vitro and in vivo.

CONCLUSION

These findings suggest that ERO1L was highly expressed in LUAD tissue, and it promoted the proliferation and metastasis of LUAD by activating the Wnt2/β-catenin signaling pathway.

Treated dentin matrix induces odontogenic differentiation of dental pulp stem cells via regulation of Wnt/β-catenin signaling

Treated dentin matrix (TDM) is an ideal scaffold material containing multiple extracellular matrix factors. The canonical Wnt signaling pathway is necessary for tooth regeneration. Thus, this study investigated whether the TDM can promote the odontogenic differentiation of human dental pulp stem cells (hDPSCs) and determined the potential role of Wnt/β-catenin signaling in this process. Different concentrations of TDM promoted the dental differentiation of the hDPSCs and meanwhile, the expression of GSK3β was decreased. Of note, the expression of the Wnt/β-catenin pathway-related genes changed significantly in the context of TDM induction, as per RNA sequencing (RNA seq) data. In addition, the experiment showed that new dentin was visible in rat mandible cultured with TDM, and the thickness was significantly thicker than that of the control group. In addition, immunohistochemical staining showed lower GSK3β expression in new dentin. Consistently, the GSK3β knockdown hDPSCs performed enhanced odotogenesis compared with the control groups. However, GSK3β overexpressing could decrease odotogenesis of TDM-induced hDPSCs. These results were confirmed in immunodeficient mice and Wistar rats. These suggest that TDM promotes odontogenic differentiation of hDPSCs by directly targeting GSK3β and activating the canonical Wnt/β-catenin signaling pathway and provide a theoretical basis for tooth regeneration engineering.

GTPBP2 positively regulates the invasion, migration and proliferation of non-small cell lung cancer

Lung cancer is one of the most common malignant tumors in the world, and the mortality rate ranks first among various malignant tumors. GTP-binding proteins (guanosine 5'-triphosphate-binding proteins, GTPBPs) are a type of protein with signal transduction function, have GTP hydrolase activity, and play an important role in cell signal transmission, cytoskeletal regulation, protein synthesis and other activities. GTPBP2 is one of the members of the G protein superfamily. Research on GTPBP2 is currently focused on human genetics, and its research in tumors has not been reported. First, Western blot and quantitative real-time PCR were used to analyze the expression differences of 12 cases of GTPBP2 in human NSCLC fresh cancer tissues and adjacent tissues. Then we selected 112 cases of NSCLC cancer tissues and 65 adjacent tissues for immunohistochemistry experiments to analyze the relationships between the expression of GTPBP2 and clinical pathological parameters and prognosis, we found that GTPBP2 is highly expressed in NSCLC cancer tissues, and the high expression of GTPBP2 is related to pTNM stage and lymph node metastasis. In addition, after GTPBP2 knockdown, GTPBP2 can promote the proliferation and invasion of NSCLC cell lines by up-regulating RhoC and MMP-9, and up-regulate cyclinD1, CDK4 and c-myc, and down-regulate P27 to promote the invasion of NSCLC cell lines. In addition, GTPBP2 negatively regulates Axin to promote β-catenin expression, thereby activating Wnt/β-catenin signaling, and promoting the occurrence of NSCLC.

Carboxylesterase Notum Is a Druggable Target to Modulate Wnt Signaling

Regulation of the Wnt signaling pathway is critically important for a number of cellular processes in both development and adult mammalian biology. This Perspective will provide a summary of current and emerging therapeutic opportunities in modulating Wnt signaling, especially through inhibition of Notum carboxylesterase activity. Notum was recently shown to act as a negative regulator of Wnt signaling through the removal of an essential palmitoleate group. Inhibition of Notum activity may represent a new approach to treat disease where aberrant Notum activity has been identified as the underlying cause. Reliable screening technologies are available to identify inhibitors of Notum, and structural studies are accelerating the discovery of new inhibitors. A selection of these hits have been optimized to give fit-for-purpose small molecule inhibitors of Notum. Three noteworthy examples are LP-922056 (26), ABC99 (27), and ARUK3001185 (28), which are complementary chemical tools for exploring the role of Notum in Wnt signaling.

The role and mechanism of β-arrestin2 in signal transduction

β-arrestin2 is a ubiquitously expressed scaffold protein localized on the cytoplasm and plasma membrane. It was originally found to bind to GPCRs, uncoupling G proteins and receptors' binding and inhibiting the signal transduction of the GPCRs. Further investigations have revealed that β-arrestin2 not only mediates the desensitization of GPCRs but also serves as a multifunctional scaffold to mediate receptor internalization, kinase activation, and regulation of various signaling pathways, such as TLR4/NF-κB, MAPK, Wnt, TGF-β, and AMPK/mTOR pathways. β-arrestin2 regulates cell invasion, migration, autophagy, angiogenesis, and anti-inflammatory effects by regulating various signaling pathways, which play a vital role in many physiological and pathological processes. This paper reviews the structure and function of β-arrestin2, the regulation of β-arrestin2 based signaling pathways. The role and mechanism of β-arrestin2 signaling have been delineated in sufficient detail. The prospect of regulating the expression and activity of β-arrestin2 in multisystem diseases holds substantial therapeutic promise.

Oxysterols and mesenchymal stem cell biology

Mesenchymal stem cells have the ability to differentiate into several cell types when exposed to determined substances, including oxysterols. Oxysterols are cholesterol products derived from its auto-oxidation by reactive species or from enzymatic action. They are present in the body in low quantities under physiological conditions and exhibit several physiological and pharmacological actions according to both the types of oxysterol and tissue. Some of them are cytotoxic while others have been shown to promote cell differentiation through the action on several different receptors, such as nuclear LXR receptors and Smoothened receptor ligands. Here, we review the main pathways by which oxysterols have been associated with cell differentiation and death of mesenchymal stem cells.

Mining Natural Compounds to Target WNT Signaling: Land and Sea Tales

WNT signaling plays paramount roles in organism development, physiology, and disease, representing a highly attractive target for drug development. However, no WNT-modulating drugs have been approved, with several candidates trudging through the early clinical trials. This delay instigates alternative approaches to discover WNT-modulating drugs. Natural products were the source of therapeutics for centuries, but the chemical diversity they offer, especially when looking at different taxonomic groups and habitats, is still to a large extent unexplored. These considerations urge researchers to screen natural compounds for the WNT-modulatory activities. Since several reviews on such endeavors exist, we here have attempted to present these efforts as "Land and sea tales" (citing the book title by Rudyard Kipling) superimposing them onto the traditional pipeline of drug discovery and early development. In doing so, we illustrate each step of the pipeline with case studies stemming from our own research. It will become obvious that several steps of the pipeline need to be modified when applied to natural products rather than to synthetic libraries. Yet the main message of this chapter is that natural compounds represent a powerful source for the WNT signaling modulators and can be developed towards drug candidates against WNT-dependent maladies.

MicroRNA-31 Regulates Expression of Wntless in Both Drosophila melanogaster and Human Oral Cancer Cells

Recent comparative studies have indicated distinct expression profiles of short, non-coding microRNAs (miRNAs) in various types of cancer, including oral squamous cell carcinoma (OSCC). In this study, we employed a hybrid approach using Drosophila melanogaster as well as OSCC cell lines to validate putative targets of oral cancer-related miRNAs both in vivo and in vitro. Following overexpression of Drosophila miR-31, we found a significant decrease in the size of the imaginal wing discs and downregulation of a subset of putative targets, including wntless (wls), an important regulator of the Wnt signaling pathway. Parallel experiments performed in OSCC cells have also confirmed a similar miR-31-dependent regulation of human WLS that was not initially predicted as targets of human miR-31. Furthermore, we found subsequent downregulation of cyclin D1 and c-MYC, two of the main transcriptional targets of Wnt signaling, suggesting a potential role of miR-31 in regulating the cell cycle and proliferation of OSCC cells. Taken together, our Drosophila-based in vivo system in conjunction with the human in vitro platform will thus provide a novel insight into a mammal-to-Drosophila-to-mammal approach to validate putative targets of human miRNA and to better understand the miRNA-target relationships that play an important role in the pathophysiology of oral cancer.

RBBP4 promotes colon cancer malignant progression via regulating Wnt/β-catenin pathway

BACKGROUND

Our previous study demonstrated that RBBP4 was upregulated in colon cancer and correlated with poor prognosis of colon cancer and hepatic metastasis. However, the potential biological function of RBBP4 in colon cancer is still unknown.

AIM

To investigate the biological role and the potential mechanisms of RBBP4 in colon cancer progression.

METHODS

Real-time polymerase chain reaction and western blot analysis were used to detect the expression of RBBP4 in colon cancer cell lines. The cell proliferation and viability of SW620 and HCT116 cells with RBBP4 knockdown was detected by Cell Counting Kit-8 and 5-ethynyl-2’-deoxyuridine staining. The transwell assay was used to detect the invasion and migration capabilities of colon cancer cells with RBBP4 knockdown. Flow cytometry apoptosis assay was used to detect the apoptosis of colon cancer cells. Western blotting analysis was used to detect the expression of epithelial-mesenchymal transition and apoptosis related markers in colon cancer. The nuclear translocation of β-catenin was examined by Western blotting analysis in colon cancer cells with RBBP4 knockdown. The TOPFlash luciferase assay was used to detect the effect of RBBP4 on Wnt/β-catenin activation. The rescue experiments were performed in colon cancer cells treated with Wnt/β-catenin activator LiCl and RBBP4 knockdown.

RESULTS

We found that RBBP4 was highly expressed in colon cancer cell lines. The 5-ethynyl-2’-deoxyuridine assay showed that knockdown of RBBP4 significantly inhibited cell proliferation. RBBP4 inhibition reduced cell invasion and migration via regulating proteins related to epithelial-mesenchymal transition. Knockdown of RBBP4 significantly inhibited survivin-mediated apoptosis. Mechanistically, the TOPFlash assay showed that RBBP4 knockdown increased activity of the Wnt/β-catenin pathway. Meanwhile, RBBP4 knockdown suppressed nuclear translocation of β-catenin. With Wnt/β-catenin activator, rescue experiments suggested that the role of RBBP4 in colon cancer progression was dependent on Wnt/β-catenin pathway.

CONCLUSION

RBBP4 promotes colon cancer development via increasing activity of the Wnt/β-catenin pathway. RBBP4 may serve as a novel therapeutic target in colon cancer.