Therapeutic potential of targeting the Wnt/β-catenin pathway in the treatment of pancreatic cancer

The Wnt/β-catenin pathway is an important, dysregulated pathway in several tumor types, including pancreatic ductal adenocarcinoma. Although the activation of this pathway is an important component of normal development, its aberrant activation resulting from activating or inactivating mutations in the CTNNB1 gene locus, or in the negative regulators AXIN and APC involving stabilization of β-catenin, and activation of target genes leads to a more aggressive phenotype, suggesting its potential value as a therapeutic target in the treatment of pancreatic ductal adenocarcinoma. A number of small molecule and biologic agents have now been developed for targeting this pathway. This review summarizes the current knowledge about the therapeutic potential of targeting the Wnt pathway with particular emphasis on preclinical/clinical studies in the treatment of pancreatic ductal adenocarcinoma.     

Wnt/β-catenin signaling pathway in severe preeclampsia

This study aims to elucidate the mechanisms of Wnt/β-catenin signaling pathway in the development of preeclampsia (PE). The mRNA levels of Wnt1, β-catenin, c-myc and cyclinD1 were determined by real-time PCR in the placentas. Moreover, the expression levels of Wnt1, β-catenin, Dickkopf-1 (DKK1) and glycogen synthase kinase 3β (GSK-3β) proteins were detected by Western blot. Immunohistochemistry was used in placental tissue microarray to localize the expression of Wnt1, β-catenin, DKK1 proteins in the placentas of two groups. Compared with the control placentas, the mRNA levels of Wnt1, β-catenin, c-myc and cyclinD1 were decreased in the severe preeclamptic placentas. The Western blot results showed that the expression levels of Wnt1, β-catenin, and GSK-3β proteins were significantly elevated in the control group, while the expression level of DKK1 was significantly decreased. In addition, the staining intensity of Wnt1, β-catenin were weaker in the placentas of the severe PE group while the staining intensity of DKK1 was significantly stronger in the placentas of the severe PE group. Wnt/β-catenin signaling pathway may play a significant role in the pathogenesis of PE by regulating the invasion and proliferation of trophoblast.     

The E6 oncoprotein from HPV16 enhances the canonical Wnt/β-catenin pathway in skin epidermis in vivo

The contribution of the Wnt signaling pathway to human papilloma virus (HPV)-induced carcinogenesis is poorly understood. In high-grade dysplastic lesions that are caused by high-risk HPVs (HR-HPV), β-catenin is often located in the cell nucleus, which suggests that Wnt pathway may be involved in the development of HPV-related carcinomas. Most of the oncogenic potential of HR-HPVs resides on the PDZ-binding domain of E6 protein. We hypothesized that the PDZ-binding domain of the HPV16-E6 oncoprotein induces the nuclear accumulation of β-catenin due to its capacity to degrade PDZ-containing cellular targets. To test this hypothesis, we evaluated the staining pattern of β-catenin in the skin epidermis of transgenic mice expressing the full-length E6 oncoprotein (K14E6 mice) and measured LacZ gene expression in K14E6 mice that were crossed with a strain expressing LacZ that was knocked into the Axin2 locus (Axin2(+/LacZ) mice). Here, we show that the E6 oncoprotein enhances the nuclear accumulation of β-catenin, the accumulation of cellular β-catenin-responsive genes, and the expression of LacZ. None of these effects were observed when a truncated E6 oncoprotein that lacks the PDZ-binding domain was expressed alone (K14E6ΔPDZ mice) or in combination with Axin2(+/LacZ). Conversely, cotransfection with either E6 or E6ΔPDZ similarly enhanced canonical Wnt signaling in short-term in vitro assays that used a luciferase Wnt/β-catenin/TCF-dependent promoter. We propose that the activation of canonical Wnt signaling could be induced by the HPV16-E6 oncoprotein; however, the participation of the E6 PDZ-binding domain seems to be important in in vivo models only.     

Gene–gene interactions of the Wnt/β-catenin signaling pathway in knee osteoarthritis

Molecular Biology Reports - This study was designed to investigate whether genetic polymorphisms of the Wnt/β-catenin signaling pathway and its interactions are involved in the development of...     

Activation of the Wnt/β-catenin signaling pathway by mechanical ventilation is associated with ventilator-induced pulmonary fibrosis in healthy lungs

Background

Mechanical ventilation (MV) with high tidal volumes (V_T) can cause or aggravate lung damage, so-called ventilator induced lung injury (VILI). The relationship between specific mechanical events in the lung and the cellular responses that result in VILI remains incomplete. Since activation of Wnt/β-catenin signaling has been suggested to be central to mechanisms of lung healing and fibrosis, we hypothesized that the Wnt/β-catenin signaling plays a role during VILI.

Methodology/Principal Findings

Prospective, randomized, controlled animal study using adult, healthy, male Sprague-Dawley rats. Animals (n = 6/group) were randomized to spontaneous breathing or two strategies of MV for 4 hours: low tidal volume (V_T) (6 mL/kg) or high V_T (20 mL/kg). Histological evaluation of lung tissue, measurements of WNT5A, total β-catenin, non-phospho (Ser33/37/Thr41) β-catenin, matrix metalloproteinase-7 (MMP-7), cyclin D1, vascular endothelial growth factor (VEGF), and axis inhibition protein 2 (AXIN2) protein levels by Western blot, and WNT5A, non-phospho (Ser33/37/Thr41) β-catenin, MMP-7, and AXIN2 immunohistochemical localization in the lungs were analyzed. High-V_T MV caused lung inflammation and perivascular edema with cellular infiltrates and collagen deposition. Protein levels of WNT5A, non-phospho (Ser33/37/Thr41) β-catenin, MMP-7, cyclin D1, VEGF, and AXIN2 in the lungs were increased in all ventilated animals although high-V_T MV was associated with significantly higher levels of WNT5A, non-phospho (Ser33/37/Thr41) β-catenin, MMP-7, cyclin D1, VEGF, and AXIN2 levels.

Conclusions/Significance

Our findings demonstrate that the Wnt/β-catenin signaling pathway is modulated very early by MV in lungs without preexistent lung disease, suggesting that activation of this pathway could play an important role in both VILI and lung repair. Modulation of this pathway might represent a therapeutic option for prevention and/or management of VILI.     

Regulation of cadherin expression in the chicken neural crest by the Wnt/β-catenin signaling pathway

In neural crest cell development, the expression of the cell adhesion proteins cadherin-7 and cadherin-11 commences after delamination of the neural crest cells from the neuroepithelium. The canonical Wnt signaling pathway is known to drive this delamination step and is a candidate for inducing expression of these cadherins at this time. This project was initiated to investigate the role of canonical Wnt signaling in the expression of cadherin-7 and cadherin-11 by treating neural crest cells with Wnt3a ligand. Expression of cadherin-11 was first confirmed in the neural crest cells for the chicken embryo. The changes in the expression level of cadherin-7 and -11 following the treatment with Wnt3a were studied using real-time RT-PCR and immunostaining. Statistically significant upregulation in the mRNA expression of cadherin-7 and cadherin-11 and in the amount of cadherin-7 and cadherin-11 protein found in cell-cell interfaces between neural crest cells was observed in response to Wnt, demonstrating that cadherin-7 and cadherin-11 expressed by the migrating neural crest cells can be regulated by the canonical Wnt pathway.Key words: neural crest, Wnt, cadherin-7, cadherin-11     

Wnk kinases are positive regulators of canonical Wnt/β-catenin signalling

Wnt/β-catenin signalling is central to development and its regulation is essential in preventing cancer. Using phosphorylation of Dishevelled as readout of pathway activation, we identified Drosophila Wnk kinase as a new regulator of canonical Wnt/β-catenin signalling. WNK kinases are known for regulating ion co-transporters associated with hypertension disorders. We demonstrate that wnk loss-of-function phenotypes resemble canonical Wnt pathway mutants, while Wnk overexpression causes gain-of-function canonical Wnt-signalling phenotypes. Importantly, knockdown of human WNK1 and WNK2 also results in decreased Wnt signalling in mammalian cell culture, suggesting that Wnk kinases have a conserved function in ensuring peak levels of canonical Wnt signalling.     

Functions of the Wnt/β-catenin pathway in an anemia-induced zebrafish model of cardiomyopathy are location dependent

Recent evidence that the heart is not a terminally-differentiated organ has provided more credence to investigations of pathways involved in inducing cardiomyocyte (CM) hyperplasia as a therapy for heart disease. Here, we leveraged zebrafish as a novel vertebrate model of cardiomyopathy to explore the therapeutic potential based on the Wnt/β-catenin signaling. In the anemia-induced zebrafish model of cardiomyopathy (tr265), we detected differently regulated CM hyperplasia and CM hypertrophy in the compact region and the trabecular region. To assess the effects of the Wnt/β-catenin pathway on these two regions, the anemia line was crossed with heat shock-inducible transgenic fish to upregulate or downregulate the pathway. Upregulation resulted in increased cardiomyocyte hyperplasia in the heart and increased cardiomyocyte hypertrophy in the trabecular region, while downregulation resulted in reduced cardiomyocyte hyperplasia in the heart and reduced cardiomyocyte hypertrophy in the trabecular region. Importantly, upregulation of the pathway resulted in improved fish survival, while downregulation decreased it. In summary, our data suggested that (1) the compact region and the trabecular region respond differently during cardiac remodeling; (2) activation of the Wnt/β-catenin pathway might exert a cardioprotective function via promoting cardiomyocyte hyperplasia.     

Distinctive microRNA signature associated of neoplasms with the Wnt/β-catenin signaling pathway

As the crucial biological regulators, microRNAs that act by suppressing their target genes are involved in a variety of pathophysiological processes. It is generally accepted that microRNAs are often dysregulated in many types of neoplasm and other human diseases. In neoplasm, microRNAs may function as oncogenes or tumor suppressors. As constitutive activation of the Wnt signaling pathway is a common feature of neoplasm and contributes to its development, progression and metastasis in various cancers, numerous studies have revealed that microRNA-mediated gene regulation are interconnected with the Wnt/β-catenin signaling pathway, forming a Wnt/β-catenin–microRNA regulatory network, which is critical to successful targeting of the Wnt/β-catenin pathway for oncotherapy. In this review, we aim to accumulate recent advances on microRNAs that work in tandem with Wnt/β-catenin signaling in tumorigenesis, with particular focus on how microRNAs affect Wnt/β-catenin activity as well as how microRNAs are regulated through the Wnt/β-catenin pathway.