Vitamin D receptor deficiency enhances Wnt/β-catenin signaling and tumor burden in colon cancer

Aberrant activation of the Wnt/β-catenin pathway is critical for the initiation and progression of most colon cancers. This activation provokes the accumulation of nuclear β-catenin and the induction of its target genes. Apc(min/+) mice are the most commonly used model for colon cancer. They harbor a mutated Apc allele and develop intestinal adenomas and carcinomas during the first months of life. This phenotype is caused by the mutation of the second Apc allele and the consequent accumulation of nuclear β-catenin in the affected cells. Here we describe that vitamin D receptor (VDR) is a crucial modulator of nuclear β-catenin levels in colon cancer in vivo. By appropriate breeding of Apc(min/+) mice and Vdr(+/-) mice we have generated animals expressing a mutated Apc allele and two, one, or none Vdr wild type alleles. Lack of Vdr increased the number of colonic Aberrant Crypt Foci (ACF) but not that of adenomas or carcinomas in either small intestine or colon. Importantly, colon ACF and tumors of Apc(min/+)Vdr(-/-) mice had increased nuclear β-catenin and the tumors reached a larger size than those of Apc(min/+)Vdr(+/+). Both ACF and carcinomas in Apc(min/+)Vdr(-/-) mice showed higher expression of β-catenin/TCF target genes. In line with this, VDR knock-down in cultured human colon cancer cells enhanced β-catenin nuclear content and target gene expression. Consistently, VDR depletion abrogated the capacity of 1,25(OH)(2)D(3) to promote the relocation of β-catenin from the nucleus to the plasma membrane and to inhibit β-catenin/TCF target genes. In conclusion, VDR controls the level of nuclear β-catenin in colon cancer cells and can therefore attenuate the impact of oncogenic mutations that activate the Wnt/β-catenin pathway.     

Estrogen receptor alpha regulates the Wnt/β-catenin signaling pathway in colon cancer by targeting the NOD-like receptors

It has been reported that estrogen receptors (ERs) participate in carcinogenesis by directly regulating NOD-like receptors (NLRs). However, the expression profiles of ERs and NLRs in tumor and the ER-NLR regulated signaling pathway are not clear. In this study, we summarized gene expression profiles of ERs and NLRs across normal and tumor tissue by comprehensive data mining. Then we explored the ER-NLR regulated signaling pathway by RNA sequencing (RNA-seq). The results showed that the NLRs and ERs were differentially expressed in different neoplasm tissues. Such expression discrepancies might influence inflammatory regulation and tumorigenesis. Importantly, we identified that ER-NLR regulate Wnt/β-catenin pathway in colon cancer. Taking colon adenocarcinoma (COAD) as example, we found that Wnt2b/LRP8/Dvl1/Axin2/GSK3a/APC/β-catenin genes were differentially expressed in ER^−/− mouse colon tissue and colon cancer cells. The selective ERα antagonist could significantly decrease Wnt2b/LRP8/Dvl1 expression, increase destruction complex (Axin2/GSK3a/APC) expression, and promote degradation of β-catenin in colon carcinoma cell by inhibited NLRP3 expression. In short, the research demonstrates that NLRs are potential biomarkers for cancer, and ERs can regulate the Wnt/β-catenin signaling pathway in cancer by targeting the NLRs. Our results provide a possible signaling pathway in which ER-NLR is correlated with Wnt/β-catenin.     

Gastrin-17 induces gastric cancer cell epithelial-mesenchymal transition via the Wnt/β-catenin signaling pathway

Journal of Physiology and Biochemistry - Gastric cancer (GC) is one of the most common cancers, with most patients often succumbing to death as a result of tumor metastasis. Recent work has...     

On the role of Wnt/β-catenin signaling in stem cells

Background

Stem cells are mainly characterized by two properties: self-renewal and the potency to differentiate into diverse cell types. These processes are regulated by different growth factors including members of the Wnt protein family. Wnt proteins are secreted glycoproteins that can activate different intracellular signaling pathways.

Scope of review

Here we summarize our current knowledge on the role of Wnt/β-catenin signaling with respect to these two main features of stem cells.

Major conclusions

A particular focus is given on the function of Wnt signaling in embryonic stem cells. Wnt signaling can also improve reprogramming of somatic cells towards iPS cells highlighting the importance of this pathway for self-renewal and pluripotency. As an example for the role of Wnt signaling in adult stem cell behavior, we furthermore focus on intestinal stem cells located in the crypts of the small intestine.

General significance

A broad knowledge about stem cell properties and the influence of intrinsic and extrinsic factors on these processes is a requirement for the use of these cells in regenerative medicine in the future or to understand cancer development in the adult. This article is part of a Special Issue entitled Biochemistry of Stem Cells.     

Activation of Wnt/β-catenin protein signaling induces mitochondria-mediated apoptosis in hematopoietic progenitor cells

The canonical Wnt/β-catenin signaling is activated during development, tumorigenesis, and in adult homeostasis, yet its role in maintenance of hematopoietic stem/progenitor cells is not firmly established. Here, we demonstrate that conditional expression of an active form of β-catenin in vivo induces a marked increase in the frequency of apoptosis in hematopoietic stem/progenitor cells (HSCs/HPCs). Activation of Wnt/β-catenin signaling in HPCs in vitro elevates the activity of caspases 3 and 9 and leads to a loss of mitochondrial membrane potential (ΔΨ(m)), indicating that it induces the intrinsic mitochondrial apoptotic pathway. In vivo, expression of activated β-catenin in HPCs is associated with down-regulation of Bcl2 and expression of Casp3. Bone marrow transplantation assays reveal that enhanced cell survival by a Bcl2 transgene re-establishes the reconstitution capacity of HSCs/HPCs that express activated β-catenin. In addition, a Bcl2 transgene prevents exhaustion of these HSCs/HPCs in vivo. Our data suggest that activation of the Wnt/β-catenin pathway contributes to the defective function of HPCs in part by deregulating their survival.     

miR-612 suppresses the stemness of liver cancer via Wnt/β-catenin signaling

Previous research showed that microRNA-612 (miR-612) has inhibitory effects on cell proliferation, migration, invasion, and metastasis of hepatocellular carcinoma (HCC). AKT2 was confirmed to be a direct target of miR-612, through which the epithelial–mesenchymal transition (EMT) and metastasis of HCC were inhibited. Our present findings reveal that miR-612 is able to suppress the stemness of HCC by reducing the number and size of tumorspheres as well as clone formation in soft agar, and to relieve drug resistance to cisplatin and 5-fluorouracil. In addition, miR-612 hampered the capacity of tumorigenesis in NOD/SCID mice and redistributed the tumor invasive frontier of miR-612-modulating cells. Finally, our findings suggest that Wnt/β-catenin signaling is required in the regulation of EMT-associated stem cell-like traits by miR-612.     

Wnt/β-catenin signaling in hepatic organogenesis

Wnt/β-catenin signaling has come to the forefront of liver biology in recent years. This pathway regulates key pathophysiological events inherent to the liver including development, regeneration, and cancer, by dictating several biological processes such as proliferation, apoptosis, differentiation, adhesion, zonation and metabolism in various cells of the liver. This review will examine the studies that have uncovered the relevant roles of Wnt/β-catenin signaling during the process of liver development. We will discuss the potential roles of Wnt/β-catenin signaling during the phases of development, including competence, hepatic induction, expansion, and morphogenesis. In addition, we will discuss the role of negative and positive regulation of this pathway and how the temporal expression of Wnt/β-catenin can direct key processes during hepatic development. We will also identify some of the major deficits in the current understanding of the role of Wnt/β-catenin signaling in liver development in order to provide a perspective for future studies. Thus, this review will provide a contextual overview of the role of Wnt/β-catenin signaling during hepatic organogenesis.     

Identification of DK419, a potent inhibitor of Wnt/β-catenin signaling and colorectal cancer growth

The Wnt signaling pathway is critical for normal tissue development and is an underlying mechanism of disease when dysregulated. Previously, we reported that the drug Niclosamide inhibits Wnt/β-catenin signaling by decreasing the cytosolic levels of Dishevelled and β-catenin, and inhibits the growth of colon cancers both in vitro and in vivo. Since the discovery of Niclosamide’s anthelmintic activity, a growing body of literature indicates that Niclosamide is a multifunctional drug. In an effort to identify derivatives of Niclosamide with improved pharmacokinetic properties that maintain the multifunctional drug activity of Niclosamide for clinical evaluation, we designed DK419, a derivative containing a 1H-benzo[d]imidazole-4-carboxamide substructure, using the structure-activity relationships (SAR) of the Niclosamide salicylanilide chemotype. Similar to Niclosamide, we found DK419 inhibited Wnt/β-catenin signaling, altered cellular oxygen consumption rate and induced production of pAMPK. Moreover, we found DK419 inhibited the growth of CRC tumor cells in vitro, had good plasma exposure when dosed orally, and inhibited the growth of patient derived CRC240 tumor explants in mice dosed orally. DK419, a derivative of Niclosamide with multifunctional activity and improved pharmacokinetic properties, is a promising agent to treat colorectal cancer, Wnt-related diseases and other diseases in which Niclosamide has demonstrated functional activity.     

Roles of Wnt/β-catenin signaling in the gastric cancer stem cells proliferation and salinomycin treatment

The Wnt1 protein, a secreted ligand that activates Wnt signaling pathways, contributes to the self-renewal of cancer stem cells (CSCs) and thus may be a major determinant of tumor progression and chemoresistance. In a series of gastric cancer specimens, we found strong correlations among Wnt1 expression, CD44 expression, and the grade of gastric cancer. Stable overexpression of Wnt1 increased AGS gastric cancer cells'' proliferation rate and spheroids formation, which expressed CSC surface markers Oct4 and CD44. Subcutaneous injection of nude mice with Wnt1-overexpressing AGS cells resulted in larger tumors than injection of control AGS cells. Salinomycin, an antitumor agent, significantly reduced the volume of tumor caused by Wnt1-overexpressing AGS cells in vivo. This is achieved by inhibiting the proliferation of CD44+Oct4+ CSC subpopulation, at least partly through the suppression of Wnt1 and β-catenin expression. Taken together, activation of Wnt1 signaling accelerates the proliferation of gastric CSCs, whereas salinomycin acts to inhibit gastric tumor growth by suppressing Wnt signaling in CSCs. These results suggest that Wnt signaling might have a critical role in the self-renewal of gastric CSCs, and salinomycin targeting Wnt signaling may have important clinical applications in gastric cancer therapy.     

Urolithin B suppresses tumor growth in hepatocellular carcinoma through inducing the inactivation of Wnt/β-catenin signaling

Consumption of dietary ellagitannins (ETs) has been proven to benefit multiple chronic health disorders including cancers and cardiovascular diseases. Urolithins, gut microbiota metabolites derived from ETs, are considered as the molecules responsible for these health effects. Previous studies have demonstrated that urolithins exhibit antiproliferative effects on prostate, breast, and colon cancers. However, as for hepatocellular carcinoma (HCC), it remains elusive. Herein, we aim to investigate the function of urolithin B (UB), a member of urolithins family, in HCC. The effects of UB on cell viability, cell cycle and apoptosis were evaluated in HCC cells, and we found UB could inhibit the proliferation of HCC cells, which resulted from cell cycle arrest and apoptosis. Furthermore, UB could increase phosphorylated β-catenin expression and block its translocation from nuclear to cytoplasm, thus inducing the inactivation of Wnt/β-catenin signaling. Using a xenograft mice model, UB was found to suppress tumor growth in vivo. In conclusion, our data demonstrated that UB could inhibit the proliferation of HCC cells in vitro and in vivo via inactivating Wnt/β-catenin signaling, suggesting UB could be a promising candidate in the development of anticancer drugs targeting HCC.     

Upregulated microRNA-301a in breast cancer promotes tumor metastasis by targeting PTEN and activating Wnt/β-catenin signaling

MicroRNAs (miRNAs) are strongly implicated in many cancers, including breast cancer. Recently, microRNA-301a (miR-301a) has been proved to play a substantial role in gastric cancer, but its functions in the context of breast cancer remain unknown. Here we report that miR-301a was markedly upregulated in primary tumor samples from patients with distant metastases and pro-metastatic breast cancer cell lines. Gain-of-function and loss-of-function studies showed that ectopic overexpression of miR-301a promoted breast cancer cell migration, invasion and metastasis both in vitro and in vivo. Notably, Wnt/β-catenin signaling was hyperactivated in metastatic breast cancer cells that express miR-301a, and mediated miR-301a-induced invasion and metastasis. Furthermore, miR-301a directly targeted and suppressed PTEN, one negative regulator of the Wnt/β-catenin signaling cascade. These results demonstrate that miR-301a maintains constitutively activated Wnt/β-catenin signaling by directly targeting PTEN, which promotes breast cancer invasion and metastasis. Taken together, our findings reveal a new regulatory mechanism of miR-301a and suggest that miR-301a might be a potential target in breast cancer therapy.     

Requirement of Wnt/β-catenin signaling in pronephric kidney development

The pronephric kidney controls water and electrolyte balance during early fish and amphibian embryogenesis. Many Wnt signaling components have been implicated in kidney development. Specifically, in Xenopus pronephric development as well as the murine metanephroi, the secreted glycoprotein Wnt-4 has been shown to be essential for renal tubule formation. Despite the importance of Wnt signals in kidney organogenesis, little is known of the definitive downstream signaling pathway(s) that mediate their effects. Here we report that inhibition of Wnt/β-catenin signaling within the pronephric field of Xenopus results in significant losses to kidney epithelial tubulogenesis with little or no effect on adjoining axis or somite development. We find that the requirement for Wnt/β-catenin signaling extends throughout the pronephric primordium and is essential for the development of proximal and distal tubules of the pronephros as well as for the development of the duct and glomus. Although less pronounced than effects upon later pronephric tubule differentiation, inhibition of the Wnt/β-catenin pathway decreased expression of early pronephric mesenchymal markers indicating it is also needed in early pronephric patterning. We find that upstream inhibition of Wnt/β-catenin signals in zebrafish likewise reduces pronephric epithelial tubulogenesis. We also find that exogenous activation of Wnt/β-catenin signaling within the Xenopus pronephric field results in significant tubulogenic losses. Together, we propose Wnt/β-catenin signaling is required for pronephric tubule, duct and glomus formation in Xenopus laevis, and this requirement is conserved in zebrafish pronephric tubule formation.     

A diterpenoid derivative 15-oxospiramilactone inhibits Wnt/β-catenin signaling and colon cancer cell tumorigenesis

The Wnt/β-catenin signaling pathway is a highly conserved pathway in organism evolution and regulates many biological processes. Aberrant activation of the Wnt/β-catenin signaling pathway is closely related to tumorigenesis. In order to identify potent small molecules to treat the over-activated Wnt signaling-mediated cancer, such as colon cancer, we established a mammalian cell line-based reporter gene screening system. The screen revealed a diterpenoid derivative, 15-oxospiramilactone (NC043) that inhibits Wnt3a or LiCl-stimulated Top-flash reporter activity in HEK293T cells and growth of colon cancer cells, SW480 and Caco-2. Treatment of SW480 cells with NC043 led to decreases in the mRNA and/or protein expression of Wnt target genes Axin2, Cyclin D1 and Survivin , as well as decreases in the protein levels of Cdc25c and Cdc2. NC043 did not affect the cytosol-nuclear distribution and protein level of soluble β-catenin, but decreased β-catenin/TCF4 association in SW480 cells. Moreover, NC043 inhibited anchorage-independent growth and xenograft tumorigenesis of SW480 cells. Collectively these results demonstrate that NC043 is a novel small molecule that inhibits canonical Wnt signaling downstream of β-catenin stability and may be a potential compound for treating colorectal cancer.