UBE3C Promotes Growth and Metastasis of Renal Cell Carcinoma via Activating Wnt/β-Catenin Pathway

Renal cell carcinoma (RCC) is the most common primary malignancy of the kidney and one of the most lethal genitourinary malignancies. Clear-cell renal cell carcinoma (ccRCC) has an extremely poor prognosis because of a high potential for tumor growth, vascular invasion, metastasis and recurrence. Unfortunately, the mechanism of RCC growth and metastasis is not well understood. In this report, we for the first time demonstrated ubiquitin protein ligase E3C (UBE3C) as a driving factor for RCC growth and metastasis. UBE3C expression was increased in ccRCC tissues compared with adjacent normal tissues. ccRCC patients with high UBE3C protein expression in tumors were associated with significantly worse postoperative survival. Knockdown of UBE3C expression in ACHN cells inhibited cell proliferation, migrations and invasiveness in vitro while overexpression of UBE3C in 786-O cells exerted the opposite effects. UBE3C up-regulated β-catenin protein levels and promoted β-catenin nuclear accumulation, leading to the activation of the Wnt/β-catenin signal pathway in RCC cells. Collectively, these observations suggest that UBE3C plays an important role in RCC development and progression, and UBE3C may be a novel target for prevention and treatment of ccRCC.     

Bilobalide Induces Neuronal Differentiation of P19 Embryonic Carcinoma Cells via Activating Wnt/β-Catenin Pathway

Bilobalide, a natural product extracted from Ginkgo biloba leaf, is known to exhibit a number of pharmacological activities. So far, whether it could affect embryonic stem cell differentiation is still unknown. The main aim of this study was to investigate the effect of bilobalide on P19 embryonic carcinoma cells differentiation and the underlying mechanisms. Our results showed that bilobalide induced P19 cells differentiation into neurons in a concentration- and time-dependent manner. We also found that bilobalide promoted neuronal differentiation through activation of Wnt/β-catenin signaling pathway. Exposure to bilobalide increased inactive GSK-3β phosphorylation, further induced the nuclear accumulation of β-catenin, and also up-regulated the expression of Wnt ligands Wnt1 and Wnt7a. Neuronal differentiation induced by bilobalide was totally abolished by XAV939, an inhibitor of Wnt/β-catenin pathway. These results revealed a novel role of bilobalide in neuronal differentiation from P19 embryonic cells acting through Wnt/β-catenin signaling pathway, which would provide a better insight into the beneficial effects of bilobalide in brain diseases.     

The Wnt/β-Catenin Pathway Interacts Differentially with PTHrP Signaling to Control Chondrocyte Hypertrophy and Final Maturation

Sequential proliferation, hypertrophy and maturation of chondrocytes are required for proper endochondral bone development and tightly regulated by cell signaling. The canonical Wnt signaling pathway acts through β-catenin to promote chondrocyte hypertrophy whereas PTHrP signaling inhibits it by holding chondrocytes in proliferating states. Here we show by genetic approaches that chondrocyte hypertrophy and final maturation are two distinct developmental processes that are differentially regulated by Wnt/β-catenin and PTHrP signaling. Wnt/β-catenin signaling regulates initiation of chondrocyte hypertrophy by inhibiting PTHrP signaling activity, but it does not regulate PTHrP expression. In addition, Wnt/β-catenin signaling regulates chondrocyte hypertrophy in a non-cell autonomous manner and Gdf5/Bmp signaling may be one of the downstream pathways. Furthermore, Wnt/β-catenin signaling also controls final maturation of hypertrophic chondrocytes, but such regulation is PTHrP signaling-independent.     

Age-Dependent Impaired Neurogenic Differentiation Capacity of Dental Stem Cell is Associated with Wnt/β-Catenin Signaling

Two kinds of dental stem cells (DSCs), dental pulp stem cells (DPSCs) and stem cells from human-exfoliated deciduous teeth (SHED), have been identified as novel populations of mesenchymal stem cells that can be induced to differentiate into osteoblasts, chondrocytes, adipocytes, and neuron-like cells in vitro. As we know, both of them originate from the neural crest, but have distinct characteristics and functions in vitro and in vivo. The regeneration potential of DSCs declines with advanced age; however, the mechanism of the impaired potential in DSCs has not been fully explored. In this study, we investigated whether declined neurogenic differentiation capacity is associated with an altered expression of Wnt signaling-related proteins in vitro. We compared stem cells isolated from human dental pulp in two age groups: the exfoliated deciduous teeth (5–12 years), and the third permanent teeth (45–50 years). We found that the expression levels of neuron markers, such as βIII-tubulin, microtubule-associated protein 2(MAP2), tyrosine hydroxylase (TH), and Nestin were lower in the DPSCs group compared with that in the SHED group; however, in supplementation with human recombinant Wnt1 in the medium, the DPSCs were prone to neural differentiation and expressed higher levels of neurogenic markers. In summary, our study demonstrated that Wnt/β-catenin signaling may play a vital role in the age-dependent neural differentiation of DSCs. Therefore, DSCs may provide an ideal source of stem cells that can further extend their therapeutic application in nerve injury and neurodegenerative diseases.     

Resveratrol Inhibits Breast Cancer Stem-Like Cells and Induces Autophagy via Suppressing Wnt/β-Catenin Signaling Pathway

Resveratrol, a natural polyphenolic compound, is abundantly found in plant foods and has been extensively studied for its anti-cancer properties. Given the important role of CSCs (Cancer Stem Cells) in breast tumorigenesis and progression, it is worth investigating the effects of resveratrol on CSCs. The article is an attempt to investigate the effects of resveratrol on breast CSCs. Resveratrol significantly inhibits the proliferation of BCSCs (breast cancer stem-like cells) isolated from MCF-7 and SUM159, and decreased the percentage of BCSCs population, consequently reduced the size and number of mammospheres in non-adherent spherical clusters. Accordingly, the injection of resveratrol (100 mg/kg/d) in NOD/SCID (nonobese diabetic/severe combined immunodeficient) mice effectively inhibited the growth of xenograft tumors and reduced BCSC population in tumor cells. After the reimplantation of primary tumor cells into the secondary mice for 30 d, all 6 control inoculations produced tumors, while tumor cells derived from resveratrol-treated mice only caused 1 tumor of 6 inoculations. Further studies by TEM (Transmission electron microscopy) analysis, GFP-LC3-II puncta formation assay and western blot for LC3-II, Beclin1 and Atg 7, showed that resveratrol induces autophagy in BCSCs. Moreover, resveratrol suppresses Wnt/β-catenin signaling pathway in BCSCs; over-expression of β-catenin by transfecting the plasmid markedly reduced resveratrol-induced cytotoxicity and autophagy in BCSCs. Our findings indicated that resveratrol inhibits BCSCs and induces autophagy via suppressing Wnt/β-catenin signaling pathway.     

Aluminum Trichloride Inhibited Osteoblastic Proliferation and Downregulated the Wnt/β-Catenin Pathway

Aluminum (Al) exposure inhibits bone formation. Osteoblastic proliferation promotes bone formation. Therefore, we inferred that Al may inhibit bone formation by the inhibition of osteoblastic proliferation. However, the effects and molecular mechanisms of Al on osteoblastic proliferation are still under investigation. Osteoblastic proliferation can be regulated by Wnt/β-catenin signaling pathway. To investigate the effects of Al on osteoblastic proliferation and whether Wnt/β-catenin signaling pathway is involved in it, osteoblasts from neonatal rats were cultured and exposed to 0, 0.4 mM (1/20 IC₅₀), 0.8 mM (1/10 IC₅₀), and 1.6 mM (1/5 IC₅₀) of aluminum trichloride (AlCl₃) for 24 h, respectively. The osteoblastic proliferation rates; Wnt3a, lipoprotein receptor-related protein 5 (LRP-5), T cell factor 1 (TCF-1), cyclin D1, and c-Myc messenger RNA (mRNA) expressions; and p-glycogen synthase kinase 3β (GSK3β), GSK3β, and β-catenin protein expressions indicated that AlCl₃ inhibited osteoblastic proliferation and downregulated Wnt/β-catenin signaling pathway. In addition, the AlCl₃ concentration was negatively correlated with osteoblastic proliferation rates and the mRNA expressions of Wnt3a, c-Myc, and cyclin D1, while the osteoblastic proliferation rates were positively correlated with mRNA expressions of Wnt3a, c-Myc, and cyclin D1. Taken together, these findings indicated that AlCl₃ inhibits osteoblastic proliferation may be associated with the inactivation of Wnt/β-catenin signaling pathway.     

Cell Surface Sialylation and Fucosylation Are Regulated by L1 via Phospholipase Cγ and Cooperate to Modulate Neurite Outgrowth,Cell Survival and Migration

Background

Cell surface glycosylation patterns are markers of cell type and status. However, the mechanisms regulating surface glycosylation patterns remain unknown.

Methodology/Principal Findings

Using a panel of carbohydrate surface markers, we have shown that cell surface sialylation and fucosylation were downregulated in L1^−/y neurons versus L1^+/y neurons. Consistently, mRNA levels of sialyltransferase ST6Gal1, and fucosyltransferase FUT9 were significantly reduced in L1^−/y neurons. Moreover, treatment of L1^+/y neurons with L1 antibodies, triggering signal transduction downstream of L1, led to an increase in cell surface sialylation and fucosylation compared to rat IgG-treated cells. ShRNAs for both ST6Gal1 and FUT9 blocked L1 antibody-mediated enhancement of neurite outgrowth, cell survival and migration. A phospholipase Cγ (PLCγ) inhibitor and shRNA, as well as an Erk inhibitor, reduced ST6Gal1 and FUT9 mRNA levels and inhibited effects of L1 on neurite outgrowth and cell survival.

Conclusions

Neuronal surface sialylation and fucosylation are regulated via PLCγ by L1, modulating neurite outgrowth, cell survival and migration.     

S100A8和S100A9通过Wnt/β-catenin通路影响鼻咽癌细胞生物行为的研究

为探讨S100A8和S100A9对鼻咽癌细胞系CNE2的影响及是否通过Wnt/β-catenin通路而发挥作用,以培养基添加1μg/m L S100A8/S100A9培养CNE2为实验组,采用划痕、黏附和平板克隆实验分别检测S100A8/S100A9对CNE2细胞的生物学行为影响,同时运用Western blotting检测CNE2细胞中β-catenin蛋白的累积。实验结果显示,S100A8/S100A9起促进CNE2细胞迁移(p0.05,p0.01)、基质黏附(p0.01)和平板克隆(p0.01)的作用,且添加S100A8/S100A9蛋白后1 h,CNE2细胞中β-catenin的累积明显上调。以上结果显示S100A8/S100A9可促进鼻咽癌细胞CNE2侵袭和迁移及细胞干性增强等生物学行为,其机制可能有Wnt/β-catenin通路的参与。     

Ca2+-mediated Mitochondrial Reactive Oxygen Species Metabolism Augments Wnt/β-Catenin Pathway Activation to Facilitate Cell Differentiation

Emerging evidence suggests that reactive oxygen species (ROS) can stimulate the Wnt/β-catenin pathway in a number of cellular processes. However, potential sources of endogenous ROS have not been thoroughly explored. Here, we show that growth factor depletion in human neural progenitor cells induces ROS production in mitochondria. Elevated ROS levels augment activation of Wnt/β-catenin signaling that regulates neural differentiation. We find that growth factor depletion stimulates the release of Ca²⁺ from the endoplasmic reticulum stores. Ca²⁺ subsequently accumulates in the mitochondria and triggers ROS production. The inhibition of mitochondrial Ca²⁺ uptake with simultaneous growth factor depletion prevents the rise in ROS metabolism. Moreover, low ROS levels block the dissociation of the Wnt effector Dishevelled from nucleoredoxin. Attenuation of the response amplitudes of pathway effectors delays the onset of the Wnt/β-catenin pathway activation and results in markedly impaired neuronal differentiation. Our findings reveal Ca²⁺-mediated ROS metabolic cues that fine-tune the efficiency of cell differentiation by modulating the extent of the Wnt/β-catenin signaling output.     

Macrophage Migration Inhibitory Factor Promotes Proliferation and Neuronal Differentiation of Neural Stem/Precursor Cells through Wnt/β-Catenin Signal Pathway

Macrophage migration inhibitory factor (MIF) is a highly conserved and evolutionarily ancient mediator with pleiotropic effects. Recent studies demonstrated that the receptors of MIF, including CD44, CXCR2, CXCR4 and CD74, are expressed in the neural stem/progenitor cells (NSPCs). The potential regulatory effect of MIF on NSPCs proliferation and neuronal differentiation, however, is largely unknown. Here, we investigated the effect of MIF on NSPC proliferation and neuronal differentiation, and further examined the signal pathway by which MIF transduced these signal effects in mouse NSPCs in vitro. The results showed that both Ki67-positive cells and neurosphere volumes were increased in a dose-dependent manner following MIF treatment. Furthermore, the expression of nuclear β-catenin was significantly stronger in MIF-stimulated groups than that in control groups. Conversely, administration of IWR-1, the inhibitor of Wnt/β-catenin pathway, significantly inhibited the proliferative effect of MIF on NSPCs. Immunostaining and Western blot further indicated that doublecortin (DCX) and Tuj 1, two neuronal markers, were evidently increased with MIF stimulation during NSPC differentiation, and there were more Tuj1-positive cells migrated out from neurospheres in MIF-stimulated groups than those in control groups. During NSPC differentiation, MIF increased the activity of β-galactosidase that responds to Wnt/β-catenin signaling. Wnt1 and β-catenin proteins were also up-regulated with MIF stimulation. Moreover, the expression of DCX and Tuj 1 was inhibited significantly by IWR-1. Taken together, the present study indicated that MIF enhances NSPC proliferation and promotes the neuronal differentiation, by activating Wnt/β-catenin signal pathway. The interaction between MIF and Wnt/β-catenin signal pathway may play an important role in modulating NSPC renewal and fate during brain development.     

Isoquercitrin Suppresses Colon Cancer Cell Growth in Vitro by Targeting the Wnt/β-Catenin Signaling Pathway

Flavonoids are plant-derived polyphenolic molecules that have potential biological effects including anti-oxidative, anti-inflammatory, anti-viral, and anti-tumoral effects. These effects are related to the ability of flavonoids to modulate signaling pathways, such as the canonical Wnt signaling pathway. This pathway controls many aspects of embryonic development and tissue maintenance and has been found to be deregulated in a range of human cancers. We performed several in vivo assays in Xenopus embryos, a functional model of canonical Wnt signaling studies, and also used in vitro models, to investigate whether isoquercitrin affects Wnt/β-catenin signaling. Our data provide strong support for an inhibitory effect of isoquercitrin on Wnt/β-catenin, where the flavonoid acts downstream of β-catenin translocation to the nuclei. Isoquercitrin affects Xenopus axis establishment, reverses double axes and the LiCl hyperdorsalization phenotype, and reduces Xnr3 expression. In addition, this flavonoid shows anti-tumoral effects on colon cancer cells (SW480, DLD-1, and HCT116), whereas exerting no significant effect on non-tumor colon cell (IEC-18), suggesting a specific effect in tumor cells in vitro. Taken together, our data indicate that isoquercitrin is an inhibitor of Wnt/β-catenin and should be further investigated as a potential novel anti-tumoral agent.     

S100A8 and S100A9—oxidant scavengers in inflammation

S100A8 and S100A9 are generally considered proinflammatory. Hypohalous acids generated by activated phagocytes promote novel modifications in murine S100A8 but modifications to human S100A8 are undefined and there is no evidence that these proteins scavenge oxidants in human disease. Recombinant S100A8 was exquisitely sensitive to equimolar ratios of HOCl, which generated sulfinic and sulfonic acid intermediates and novel oxathiazolidine oxide/dioxide forms (mass additions, m/z +30 and +46) on the single Cys₄₂ residue. Met₇₈(O) and Trp₅₄(+16) were also present. HOBr generated sulfonic acid intermediates and oxidized Trp₅₄(+16). Evidence for oxidation of the single Cys₃ residue in recS100A9 HOCl was weak; Met₆₃, Met₈₁, Met₈₃, and Met₉₄ were converted to Met(O) in vitro. Oxidized S100A8 was prominent in lungs from patients with asthma and significantly elevated in sputum compared to controls, whereas S100A8 and S100A9 were not significantly increased. Oxidized monomeric S100A8 was the major component in asthmatic sputum, and modifications, including the oxathiazolidine adducts, were similar to those generated by HOCl in vitro. Oxidized Met₆₃, Met₈₁, and Met₉₄ were variously present in S100A9 from asthmatic sputum. Results have broad implications for conditions under which hypohalous acid oxidants are generated by activated phagocytes. Identification in human disease of the novel S100A8 Cys derivatives typical of those generated in vitro strongly supports the notion that S100A8 contributes to antioxidant defense during oxidative stress.     

Exposure to ACEI/ARB and β-Blockers Is Associated with Improved Survival and Decreased Tumor Progression and Hospitalizations in Patients with Advanced Colon Cancer

BACKGROUND: Advanced colon cancer is associated with weight loss and decreased survival. Studies suggest that angiotensin and β-adrenergic blockade decrease colon cancer progression and ameliorate weight loss. This study aims to determine whether exposure to β-adrenoceptor blockers (BBs), angiotensin-converting enzyme inhibitors (ACEIs), or angiotensin receptor blockers (ARBs) is associated with decreased mortality, tumor progression, number of hospitalizations, or weight loss in colorectal cancer. METHODS: Retrospective chart review included patients with advanced colorectal cancer. Survival, stage, hospitalization, cancer progression, cancer treatment, and body weight history were collected. RESULTS: Two hundred sixty-two of 425 new stage III to IV colorectal cancer cases reviewed met the study criteria. Those exposed to ACEI/ARB, BB, or both were more likely to have diabetes, hypertension, and stage III colorectal cancer. Adjusting for age, presence of hypertension and diabetes, and stage, ACEI/ARB + BB exposure was associated with decreased mortality compared to unexposed individuals [hazard ratio (HR) = 0.5, confidence interval (CI) = 0.29–0.85; Cox regression, P = .01]. Fewer total and cancer-related hospitalizations and decreased cancer progression in the ACEI/ARB + BB group versus the unexposed group (HR = 0.59, CI = 0.36–0.99, P = .047) were seen. Exposure did not affect weight changes; furthermore, body weight changes from both prediagnosis and at diagnosis to 6, 12, 18, and 24 months postdiagnosis predicted survival. CONCLUSIONS: We have observed an association between exposure to a combination of ACEI/ARB + BB and increased survival, decreased hospitalizations, and decreased tumor progression in advanced colorectal cancer. Future studies will be needed to replicate these results and generalize them to broader populations. Determination of causality will require a randomized controlled trial.     

Targeted BRAF Inhibition Impacts Survival in Melanoma Patients with High Levels of Wnt/β-Catenin Signaling

Unprecedented clinical responses have been reported in advanced stage metastatic melanoma patients treated with targeted inhibitors of constitutively activated mutant BRAF, which is present in approximately half of all melanomas. We and others have previously observed an association of elevated nuclear β-catenin with improved survival in molecularly-unselected melanoma patients. This study sought to determine whether levels of Wnt/β-catenin signaling in melanoma tumors prior to treatment might predict patient responses to BRAF inhibitors (BRAFi). We performed automated quantification of β-catenin immunohistochemical expression in pretreatment BRAF-mutant tumors from 32 BRAFi-treated melanoma patients. Unexpectedly, patients with higher nuclear β-catenin in their tumors did not exhibit the survival advantage previously observed in molecularly-unselected melanoma patients who did not receive BRAFi. In cultured melanoma cells treated with long-term BRAFi, activation of Wnt/β-catenin signaling is markedly inhibited, coinciding with a loss of the enhancement of BRAFi-induced apoptosis by WNT3A observed in BRAFi-naïve cells. Together, these observations suggest that long-term treatment with BRAFi can impact the interaction between BRAF/MAPK and Wnt/β-catenin signaling to affect patient outcomes. Studies with larger patient cohorts are required to determine whether nuclear β-catenin expression correlates with clinical responses to BRAFi and to specific mechanisms of acquired resistance to BRAFi. Understanding these pathway interactions will be necessary to facilitate efforts to individualize therapies for melanoma patients.