Wnt signaling to beta-catenin involves two interactive components. Glycogen synthase kinase-3beta inhibition and activation of protein kinase C

Special Issue "Pathophysiology and Treatment of Alzheimer's Disease"

The majority of clinical trials, whose primary aims were to moderate Alzheimer's dementia (AD), have been based upon the prevailing paradigm, i [...].

High-fat diet plus HNF1A variant promotes polyps by activating β-catenin in early-onset colorectal cancer

The incidence of early-onset colorectal cancer (EO-CRC) is rising and is poorly understood. Lifestyle factors and altered genetic background possibly contribute. Here, we performed targeted exon sequencing of archived leukocyte DNA from 158 EO-CRC participants, which identified a missense mutation at p.A98V within the proximal DNA binding domain of Hepatic Nuclear Factor 1 α (HNF1AA98V, rs1800574). The HNF1AA98V exhibited reduced DNA binding. To test function, the HNF1A variant was introduced into the mouse genome by CRISPR/Cas9, and the mice were placed on either a high-fat diet (HFD) or high-sugar diet (HSD). Only 1% of the HNF1A mutant mice developed polyps on normal chow; however, 19% and 3% developed polyps on the HFD and HSD, respectively. RNA-Seq revealed an increase in metabolic, immune, lipid biogenesis genes, and Wnt/β-catenin signaling components in the HNF1A mutant relative to the WT mice. Mouse polyps and colon cancers from participants carrying the HNF1AA98V variant exhibited reduced CDX2 and elevated β-catenin proteins. We further demonstrated decreased occupancy of HNF1AA98V at the Cdx2 locus and reduced Cdx2 promoter activity compared with WT HNF1A. Collectively, our study shows that the HNF1AA98V variant plus a HFD promotes the formation of colonic polyps by activating β-catenin via decreasing Cdx2 expression.

Exploring the therapeutic and anti-tumor properties of morusin: a review of recent advances

Morusin is a natural product that has been isolated from the bark of Morus alba, a species of mulberry tree. It belongs to the flavonoid family of chemicals, which is abundantly present in the plant world and is recognized for its wide range of biological activities. Morusin has a number of biological characteristics, including anti-inflammatory, anti-microbial, neuro-protective, and antioxidant capabilities. Morusin has exhibited anti-tumor properties in many different forms of cancer, including breast, prostate, gastric, hepatocarcinoma, glioblastoma, and pancreatic cancer. Potential of morusin as an alternative treatment method for resistant malignancies needs to be explored in animal models in order to move toward clinical trials. In the recent years several novel findings regarding the therapeutic potential of morusin have been made. This aim of this review is to provide an overview of the present understanding of morusin's beneficial effects on human health as well as provide a comprehensive and up-to-date discussion of morusin's anti-cancer properties with a special focus on in vitro and in vivo studies. This review will aid future research on the creation of polyphenolic medicines in the prenylflavone family, for the management and treatment of cancers.

Role of Aβ in Alzheimer’s-related synaptic dysfunction

Synaptic dysfunction is closely related to Alzheimer’s disease (AD) which is also recognized as synaptic disorder. β-amyloid (Aβ) is one of the main pathogenic factors in AD, which disrupts synaptic plasticity and mediates the synaptic toxicity through different mechanisms. Aβ disrupts glutamate receptors, such as NMDA and AMPA receptors, which mediates calcium dyshomeostasis and damages synapse plasticity characterized by long-term potentiation (LTP) suppression and long-term depression (LTD) enhancement. As Aβ stimulates and Ca2+ influx, microglial cells and astrocyte can be activated and release cytokines, which reduces glutamate uptake and further impair synapse function. Besides, extracellular glutamate accumulation induced by Aβ mediates synapse toxicity resulting from reduced glutamate receptors and glutamate spillovers. Aβ also mediates synaptic dysfunction by acting on various signaling pathways and molecular targets, disrupting mitochondria and energy metabolism. In addition, Aβ overdeposition aggravates the toxic damage of hyperphosphorylated tau to synapses. Synaptic dysfunction plays a critical role in cognitive impairment of AD. The review addresses the possible mechanisms by which Aβ mediates AD-related synaptic impairment from distant perspectives.

Drugs and Endogenous Factors as Protagonists in Neurogenic Stimulation

Neurogenesis is a biological process characterized by new neurons formation from stem cells. For decades, it was believed that neurons only multiplied during development and in the postnatal period but the discovery of neural stem cells (NSCs) in mature brain promoted a revolution in neuroscience field. In mammals, neurogenesis consists of migration, differentiation, maturation, as well as functional integration of newborn cells into the pre-existing neuronal circuit. Actually, NSC density drops significantly after the first stages of development, however in specific places in the brain, called neurogenic niches, some of these cells retain their ability to generate new neurons and glial cells in adulthood. The subgranular (SGZ), and the subventricular zones (SVZ) are examples of regions where the neurogenesis process occurs in the mature brain. There, the potential of NSCs to produce new neurons has been explored by new advanced methodologies and in neuroscience for the treatment of brain damage and/or degeneration. Based on that, this review highlights endogenous factors and drugs capable of stimulating neurogenesis, as well as the perspectives for the use of NSCs for neurological and neurodegenerative diseases.

Chelerythrine Chloride Inhibits Stemness of Melanoma Cancer Stem-Like Cells (CSCs) Potentially via Inducing Reactive Oxygen Species and Causing Mitochondria Dysfunction

Growing evidence has demonstrated that high heterogeneity contributes to poor prognosis and malignancies. The existence of melanoma cancer stem-like cells (CSCs), which are a small subpopulation of melanoma cells, is responsible for tumour resistance to therapies. Recently, plant secondary metabolites have attracted attention because they are considered promising compounds that are isolated from herbs that could help to target different subpopulations of tumours. In the present study, we aimed to identify the antitumourigenic activities of the medicinal compound chelerythrine chloride (CHE) on melanoma CSCs. CHE (30-40 μmol/L) induced apoptosis in A375 and A2058 CSCs. A relatively low dose of CHE (1-5 μmol/L) inhibited the stemness of melanoma CSCs without inducing apoptosis. Coculture of CHE with A375 and A2058 cells also inhibited sphere formation and decreased stemness factors, including Nanog, Oct4, and Sox2. In functional characterizations, we observed that CHE treatment increased both cellular reactive oxygen species (ROS) and mitochondrial ROS, which resulted in a decrease in mitochondrial energy production and sphere formation. Abolishing CHE-induced ROS by N-acetyl-L-cysteine (NAC), a ROS scavenger, reversed the inhibitory effects of CHE on sphere formation, suggesting that CHE-induced ROS are the potential cause of the inhibition of sphere formation. In conclusion, CHE may exert its antitumour effect as an antistem cell natural compound, suggesting that selection of the antistem cell effects of natural compounds might be a promising strategy to overcome the poor prognosis of melanoma due to the presence of CSCs.

Anticonvulsive and Neuroprotective Effects of Eupafolin in Rats Are Associated with the Inhibition of Glutamate Overexcitation and Upregulation of the Wnt/β-Catenin Signaling Pathway

Several plant compounds have been found to possess neuroactive properties. The aim of this study was to investigate the anticonvulsant effect of eupafolin, a major active component extracted from Salvia plebeia, a herb used in traditional medicine for its anti-inflammatory properties. To this end, we assessed the anticonvulsant effects of eupafolin in rats intraperitoneally (i.p.) injected with kainic acid (KA) to elucidate this mechanism. Treatment with eupafolin (i.p.) for 30 min before KA administration significantly reduced behavioral and electrographic seizures induced by KA, similar to carbamazepine (i.p.), a widely used antiepileptic drug. Eupafolin treatment also significantly decreased KA seizure-induced neuronal cell death and glutamate elevation in the hippocampus. In addition, eupafolin notably reversed KA seizure-induced alterations in α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor subunit GluR2, glutamate decarboxylase 67 (GAD67, GABAergic enzyme), and Wnt signaling-related proteins, including porcupine, Wnt1, phosphorylated-glycogen synthase kinase-3β, β-catenin, and Bcl-2 in the hippocampus. Furthermore, the increased level of Dickkopf-related protein 1 (Dkk-1, a Wnt signaling antagonist) and the decreased level of Disheveled1 (Dvl-1, a Wnt signaling activator) in the hippocampus of KA-treated rats were reversed by eupafolin. This study provides evidence of the anticonvulsant and neuroprotective properties of eupafolin and of the involvement of regulation of glutamate overexcitation and Wnt signaling in the mechanisms of these properties. These findings support the benefits of eupafolin in treating epilepsy.

Morusin inhibits the growth of human colorectal cancer HCT116‑derived sphere‑forming cells via the inactivation of Akt pathway

The existence of colorectal cancer stem-like cells (CSC) is responsible for the failure of current treatments against colorectal cancer. Therefore, novel therapies need be developed to target CSCs. Some natural agents, including morusin have been proposed as possible candidates for this purpose. Morusin has been shown to exert antitumor effects. In the present study, it is demonstrated that morusin exerts antitumor effects on colorectal CSCs (CCSCs). The viability of human CCSCs was enhanced when the CCSCs formed spheroids in a serum-free and non-adhesive floating culture system. HCT116 sphere cells exhibited an increased proliferative capacity and a higher expression of stemness markers [octamer-binding transcription factor 4 (Oct4), Sox2 and Nanog]. Morusin inhibited the development of cancer spheroids and suppressed the growth of sphere cells via the induction of cell cycle arrest. Similarly, morusin decreased the expression levels of the stemness markers, Nanog and Oct4. The data partially revealed the molecular mechanisms involved: β-catenin signaling maintains the growth of CSCs and directly modulates the expression of Nanog and Oct4. Morusin suppressed the activity of β-catenin signaling via the inactivation of Akt; the executive β-catenin/TCF4 complex and the downstream targets, c-Myc, survivin and cyclin D1, were also downregulated. Moreover, the morusin-induced inactivation of Akt also increased the expression of p21Cip1/WAF1 and p27Kip, which can block the cell cycle by interacting with cyclin-dependent kinase (CDK) complexes. On the whole, the present study demonstrates that morusin inhibited the growth of colorectal cancer sphere cells, which were enriched with CCSCs via the inactivation of the Akt pathway.

Argonaute 3 (AGO3) promotes malignancy potential of cervical cancer via regulation of Wnt/β-catenin signaling pathway

We aimed to investigate the biological roles of Argonaute 3 (AGO3) in cervical cancer. RNA profiles containing 306 cervical cancer tissues and 13 normal samples revealed that AGO3 was significantly up-regulated in cervical cancer, and the expression of AGO3 was negatively associated with the outcome of cervical cancer patients. Cell proliferation and transwell assays showed that the depletion of AGO3 markedly inhibited cervical cancer cell growth and mobility. Importantly, we detected that knockdown of AGO3 exerted suppressive effect on cellular behaviors via inactivating Wnt/β-catenin signaling pathway. Collectively, we conclude that AGO3 is a novel tumor promoter in cervical cancer and has a potential to be a drug target and prognostic predictor of cervical cancer patients.

Is There Justification to Treat Neurodegenerative Disorders by Repurposing Drugs? The Case of Alzheimer's Disease, Lithium, and Autophagy

Lithium is the prototype mood-stabilizer used for acute and long-term treatment of bipolar disorder. Cumulated translational research of lithium indicated the drug's neuroprotective characteristics and, thereby, has raised the option of repurposing it as a drug for neurodegenerative diseases. Lithium's neuroprotective properties rely on its modulation of homeostatic mechanisms such as inflammation, mitochondrial function, oxidative stress, autophagy, and apoptosis. This myriad of intracellular responses are, possibly, consequences of the drug's inhibition of the enzymes inositol-monophosphatase (IMPase) and glycogen-synthase-kinase (GSK)-3. Here we review lithium's neurobiological properties as evidenced by its neurotrophic and neuroprotective properties, as well as translational studies in cells in culture, in animal models of Alzheimer's disease (AD) and in patients, discussing the rationale for the drug's use in the treatment of AD.

Non-pigmented ciliary epithelium derived extracellular vesicles uptake mechanism by the trabecular meshwork

Consistent with increasing findings, extracellular vesicles (EVs), consider as a major constituents of the aqueous humor, have a role as signaling mediators in glaucoma. Following secretion, EVs hold immense promise for utilization as bio-therapeutics and drug delivery vehicles due to their nature as biological nanoparticles that facilitate intercellular molecular transport. Yet, the specific pathway utilizing for transferring signals by EVs in the ocular drainage system is not fully understood. Hence, the objective of this study was to examine internalization mechanisms by which Non-Pigmented Ciliary Epithelium (NPCE)-derived EVs deliver their signals to the Trabecular Meshwork (TM) cells. EVs were isolated and size and concentration were determined. Internalization study of treated EVs with Proteinase-K to achieve removal of surface membrane proteins on EVs was conducted. Energy dependent uptake mechanism was examined under various temperatures. Using uptake inhibitors endocytosis, phagocytosis, and Wnt-TGFβ2 signaling were investigated. TM cells exposed to NPCE EVs demonstrate a significant decrease in the levels of two proteins in two Wnt-TGFb2 signaling proteins levels: p-GSK3β and β-catenin. A significant decrease in the uptake by TM cells of Proteinase-K-treated EVs was found, followed by attenuation of the Wnt-TGFβ2 proteins expression. Energy dependent uptake revealed a significant decrease in EVs internalization. The exposure of TM cells to endocytosis uptake inhibitors abolished the decrease of the Wnt-TGFβ2 proteins levels. Exposure to phagocytosis uptake inhibitor resulted in a partial inhibition of NPCE EVs effect in TM cells. The attenuation of proteins expression levels following uptake inhibitors treatment or EVs membrane proteins removal indicates that Wnt-TGFβ2 signaling in TM cells is mediated through NPCE EVs surface proteins in an active manner that involves endocytosis-dependent routes.

Small Molecule Inhibitors of Microenvironmental Wnt/β-Catenin Signaling Enhance the Chemosensitivity of Acute Myeloid Leukemia

Wnt/β-catenin signaling has been reported in Acute Myeloid leukemia, but little is known about its significance as a prognostic biomarker and drug target. In this study, we first evaluated the correlation between expression levels of Wnt molecules and clinical outcome. Then, we studied-in vitro and in vivo-the anti-leukemic value of combinatorial treatment between Wnt inhibitors and classic anti-leukemia drugs. Higher levels of β-catenin, Ser675-phospho-β-catenin and GSK-3α (total and Ser 9) were found in AML cells from intermediate or poor risk patients; nevertheless, patients presenting high activity of Wnt/β-catenin displayed shorter progression-free survival (PFS) according to univariate analysis. In vitro, many pharmacological inhibitors of Wnt signalling, i.e., LRP6 (Niclosamide), GSK-3 (LiCl, AR-A014418), and TCF/LEF (PNU-74654) but not Porcupine (IWP-2), significantly reduced proliferation and improved the drug sensitivity of AML cells cultured alone or in the presence of bone marrow stromal cells. In vivo, PNU-74654, Niclosamide and LiCl administration significantly reduced the bone marrow leukemic burden acting synergistically with Ara-C, thus improving mouse survival. Overall, our study demonstrates the antileukemic role of Wnt/β-catenin inhibition that may represent a potential new therapeutics strategy in AML.

Neurotrophic factors and target-specific retrograde signaling interactions define the specificity of classical and neuropeptide cotransmitter release at identified Lymnaea synapses

Many neurons concurrently and/or differentially release multiple neurotransmitter substances to selectively modulate the activity of distinct postsynaptic targets within a network. However, the molecular mechanisms that produce synaptic heterogeneity by regulating the cotransmitter release characteristics of individual presynaptic terminals remain poorly defined. In particular, we know little about the regulation of neuropeptide corelease, despite the fact that they mediate synaptic transmission, plasticity and neuromodulation. Here, we report that an identified Lymnaea neuron selectively releases its classical small molecule and peptide neurotransmitters, acetylcholine and FMRFamide-derived neuropeptides, to differentially influence the activity of distinct postsynaptic targets that coordinate cardiorespiratory behaviour. Using a combination of electrophysiological, molecular, and pharmacological approaches, we found that neuropeptide cotransmitter release was regulated by cross-talk between extrinsic neurotrophic factor signaling and target-specific retrograde arachidonic acid signaling, which converged on modulation of glycogen synthase kinase 3. In this context, we identified a novel role for the Lymnaea synaptophysin homologue as a specific and synapse-delimited inhibitory regulator of peptide neurotransmitter release. This study is among the first to define the cellular and molecular mechanisms underlying the differential release of cotransmitter substances from individual presynaptic terminals, which allow for context-dependent tuning and plasticity of the synaptic networks underlying patterned motor behaviour.

Effects of Arsenic on wnt/β-catenin Signaling Pathway: A Systematic Review and Meta-analysis

We aimed to systematically evaluate the regulatory effect of arsenic on wnt/β-catenin signaling pathway and to provide theoretical basis for revealing the mechanism of the relationship between arsenic and cell proliferation. The meta-analysis was carried out using Revman5.2 and Stata13.0 to describe the differences between groups with standard mean difference. We found in normal cells that the levels of wnt3a, β-catenin, glycogen synthase kinase-3β phosphorylated at serine 9 (p-GSK-3β(Ser9)), cyclinD1, proto-oncogene c-myc, and vascular endothelial growth factor (VEGF) in the arsenic intervention group were higher than those in the control group, and the level of glycogen synthase kinase-3β (GSK-3β) was lower than that in the control group (P < 0.05, respectively). Subgroup analysis showed that for a long time period (>24 h), the level of β-catenin in the arsenic intervention group was higher than that in the control group, and the level of GSK-3β of the same long-time period (>24 h) with low-dose (≤5 μM) intervention was lower than those in the control group (P < 0.05, respectively). In cancer cells, the levels of β-catenin, cyclinD1, c-myc, and VEGF in the arsenic intervention group were lower than those in the control group, while the level of GSK-3β in the arsenic intervention group was higher than that in the control group (P < 0.05, respectively). Subgroup analysis showed that the levels of β-catenin, cyclinD1, and c-myc in the high-dose (>5 μM) arsenic intervention group were lower than those in the control group, and the levels of β-catenin and cyclinD1 in the high-dose (>5 μM) arsenic intervention group were lower than those in the low-dose (≤5 μM) arsenic intervention group (P < 0.05, respectively). In addition, the regulation of arsenic on β-catenin was dose-dependent in the range of arsenic concentration from 0 to 7.5 μM. This study revealed that arsenic could upregulate wnt/β-catenin signaling pathway in normal cells and downregulate it in cancer cells, and its effect was affected by time and dose.

Neuropathological Mechanisms Associated with Pesticides in Alzheimer's Disease

Environmental toxicants have been implicated in neurodegenerative diseases, and pesticide exposure is a suspected environmental risk factor for Alzheimer’s disease (AD). Several epidemiological analyses have affirmed a link between pesticides and incidence of sporadic AD. Meanwhile, in vitro and animal models of AD have shed light on potential neuropathological mechanisms. In this paper, a perspective on neuropathological mechanisms underlying pesticides’ induction of AD is provided. Proposed mechanisms range from generic oxidative stress induction in neurons to more AD-specific processes involving amyloid-beta (Aβ) and hyperphosphorylated tau (p-tau). Mechanisms that are more speculative or indirect in nature, including somatic mutation, epigenetic modulation, impairment of adult neurogenesis, and microbiota dysbiosis, are also discussed. Chronic toxicity mechanisms of environmental pesticide exposure crosstalks in complex ways and could potentially be mutually enhancing, thus making the deciphering of simplistic causal relationships difficult.

Insulin activates hepatic Wnt/β-catenin signaling through stearoyl-CoA desaturase 1 and Porcupine

The Wnt/β-catenin pathway plays a pivotal role in liver structural and metabolic homeostasis. Wnt activity is tightly regulated by the acyltransferase Porcupine through the addition of palmitoleate. Interestingly palmitoleate can be endogenously produced by the stearoyl-CoA desaturase 1 (SCD1), a lipogenic enzyme transcriptionally regulated by insulin. This study aimed to determine whether nutritional conditions, and insulin, regulate Wnt pathway activity in liver. An adenoviral TRE-Luciferase reporter was used as a readout of Wnt/β-catenin pathway activity, in vivo in mouse liver and in vitro in primary hepatocytes. Refeeding enhanced TRE-Luciferase activity and expression of Wnt target genes in mice liver, revealing a nutritional regulation of the Wnt/β-catenin pathway. This effect was inhibited in liver specific insulin receptor KO (iLIRKO) mice and upon wortmannin or rapamycin treatment. Overexpression or inhibition of SCD1 expression regulated Wnt/β-catenin activity in primary hepatocytes. Similarly, palmitoleate added exogenously or produced by SCD1-mediated desaturation of palmitate, induced Wnt signaling activity. Interestingly, this effect was abolished in the absence of Porcupine, suggesting that both SCD1 and Porcupine are key mediators of insulin-induced Wnt/β-catenin activity in hepatocytes. Altogether, our findings suggest that insulin and lipogenesis act as potential novel physiological inducers of hepatic Wnt/β-catenin pathway.

Tissue-based metabolomics reveals potential biomarkers for cervical carcinoma and HPV infection

Aberrant metabolic regulation has been observed in human cancers, but the corresponding regulation in human papillomavirus (HPV) infection-associated cervical cancer is not well understood. Here, we explored potential biomarkers for the early prediction of cervical carcinoma based on the metabolic profile of uterine cervical tissue specimens that were positive for HPV16 infection. Fifty-two fresh cervical tissues were collected from women confirmed to have cervical squamous cell carcinoma (SCC; n = 21) or cervical intraepithelial neoplasia (CIN) stages II-III (n = 20). Eleven healthy women constituted the controls (negative controls [NCs]). Real-time polymerase chain reaction (PCR) was performed to detect HPV infection in the tissues. High-resolution magic angle spinning nuclear magnetic resonance was utilized for the analysis of the metabolic profile in the tissues. The expression of rate-limiting enzymes involved in key metabolic pathways was detected by reverse-transcription quantitative PCR. An independent immunohistochemical analysis was performed using 123 cases of paraffin-embedded cervical specimens. A profile of 17 small molecular metabolites that showed differential expression in HPV16-positive cervical SCC or CIN II-III compared with HPV-negative NC group was identified. According to the profile, the levels of α- and β-glucose decreased, those of lactate and low-density lipoproteins increased, and the expression of multiple amino acids was altered. Significantly increased transcript and protein levels of glycogen synthase kinase 3 beta (GSK3β) and glutamate decarboxylase 1 (GAD1) and decreased transcript and protein levels of pyruvate kinase muscle isozyme 2 (PKM2) and carnitine palmitoyltransferase 1A (CPT1A) were observed in the patient group (p < 0.05). HPV infection and cervical carcinogenesis drive metabolic modifications that might be associated with the aberrant regulation of enzymes related to metabolic pathways.

Chelerythrine Chloride Downregulates β-Catenin and Inhibits Stem Cell Properties of Non-Small Cell Lung Carcinoma

Plant secondary metabolites have been seen as alternatives to seeking new medicines for treating various diseases. Phytochemical scientists remain hopeful that compounds isolated from natural sources could help alleviate the leading problem in oncology—the lung malignancy that kills an estimated two million people annually. In the present study, we characterized a medicinal compound benzophenanthridine alkaloid, called chelerythrine chloride for its anti-tumorigenic activities. Cell viability assays confirmed its cytotoxicity and anti-proliferative activity in non-small cell lung carcinoma (NSCLC) cell lines. Immunofluorescence staining of β-catenin revealed that there was a reduction of nuclear content as well as overall cellular content of β-catenin after treating NCI-H1703 with chelerythrine chloride. In functional characterizations, we observed favorable inhibitory activities of chelerythrine chloride in cancer stem cell (CSC) properties, which include soft agar colony-forming, migration, invasion, and spheroid forming abilities. Interesting observations in chelerythrine chloride treatment noted that its action abides to certain concentration-specific-targeting behavior in modulating β-catenin expression and apoptotic cell death. The downregulation of β-catenin implicates the downregulation of CSC transcription factors like SOX2 and MYC. In conclusion, chelerythrine chloride has the potential to mitigate cancer growth due to inhibitory actions toward the tumorigenic activity of CSC in lung cancer and it can be flexibly adjusted according to concentration to modulate specific targeting in different cell lines.

Decursin and Decursinol Angelate Suppress Adipogenesis through Activation of β-catenin Signaling Pathway in Human Visceral Adipose-Derived Stem Cells

Visceral adiposity is closely associated with metabolic disorders and cardiovascular diseases. Angelica gigas Nakai (AGN) has been reported to possess anti-obesity effects and higher amounts of coumarin compounds are present in AGN. However, the active compounds suppressing adipogenesis in AGN and mechanisms of action have not been investigated in adipose-derived stem cells (ASCs) isolated from visceral adipose tissue (VAT). Among four coumarin compounds of AGN, decursin (D) and decursinol angelate (DA) significantly inhibited adipocyte differentiation from ASCs. D and DA downregulated CCAAT/enhancer binding protein α (C/EBPα), peroxisome proliferator-activated receptor γ (PPARγ), adipocyte fatty acid binding protein (aP2), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC) at both mRNA and protein levels. Next, treatment with adipogenic differentiation medium (ADM) on ASCs downregulated β-catenin expression at protein level, while addition of D and DA could restore protein expression and nuclear translocation of β-catenin suppressed by ADM. D and DA treatment on ADM treated ASCs increased inhibitory phosphorylation of Glycogen synthase kinase (GSK)-3β, thereby preventing β-catenin from degradation. Additionally, si-β-catenin transfection significantly upregulated protein expression of C/EBPα and PPARγ, alleviating the anti-adipogenic effect of D and DA on ADM treated ASCs. Overall, D and DA, active compounds from AGN, suppressed adipogenesis through activation of β-catenin signaling pathway in ASCs derived from human VAT, possibly using as natural anti-visceral adiposity agents.

The Alteration of CTNNBIP1 in Lung Cancer

β-catenin is a major component of the Wnt/β-catenin signaling pathway, and is known to play a role in lung tumorigenesis. β-catenin-interacting protein 1 (CTNNBIP1) is a known repressor of β-catenin transactivation. However, little is known about the role of CTNNBIP1 in lung cancer. The aim of this study was to carry out a molecular analysis of CTNNBIP1 and its effect on β-catenin signaling, using samples from lung cancer patients and various lung cancer cell lines. Our results indicate a significant inverse correlation between the CTNNBIP1 mRNA expression levels and the CTNNBIP1 promoter hypermethylation, which suggests that the promoter hypermethylation is responsible for the low levels of CTNNBIP1 present in many lung cancer patient samples. The ectopic expression of CTNNBIP1 is able to reduce the β-catenin transactivation; this then brings about a decrease in the expression of β-catenin-targeted genes, such as matrix metalloproteinase 7 (MMP7). Conversely, CTNNBIP1 knockdown is able to increase β-catenin transactivation and the expression of MMP7. In agreement with these findings, a low level of CTNNBIP1 was found to be correlated with a high level of MMP7 when a publicly available microarray dataset for lung cancer was analyzed. Also, in agreement with the above, the ectopic expression of CTNNBIP1 inhibits the migration of lung cancer cells, whereas the CTNNBIP1 knockdown increases cancer cell migration. Our findings suggest that CTNNBIP1 is a suppressor of cancer migration, thus making it a potential prognostic predictor for lung cancer.

Inhibition of protein kinase C activity inhibits osteosarcoma metastasis

INTRODUCTION

For some cancers bone is the preferred site for metastasis and involves a cascade involving transition of epithelial cells to mesenchymal cells and subsequent intravasation to the blood and lymph vessels, and finally hematogenous dissemination to perivascular niches of the bone marrow sinusoids. It has been shown that protein kinase C can aid metastasis to bone. Hence, pharmacological inhibition of protein kinase C (PKC) activity is thought of as a potential therapeutic option in bone metastatic lesions. The objective of the current study was to investigate how PKCs exert their effect on bone cancer metastasis and to test the efficacy of pharmacological inhibition of PKC on bone metastasis.

MATERIAL AND METHODS

The effect of the PKC inhibitor Go6983 on epithelial and mesenchymal cell marker expression in the osteosarcoma cell line DAN was determined by immunoblot and immunofluorescence analysis. The in vivo effect of Go6983 was evaluated with a xenograft model using DAN cells.

RESULTS

Treatment with transforming growth factor β (TGF-β) led to loss of the epithelial cell marker and gain of mesenchymal cell markers in the osteosarcoma cell line, DAN. This transition occurred concomitantly with PKC activation. TGF-β-mediated PKC activation resulted in activation of ribosomal protein 6 (S6), but not S6K1. Pharmacological inhibition of PKC activation attenuated these effects. In a xenograft model of experimental metastasis, pharmacological inhibition of PKC activation over a period of 4 weeks reduced both tumor burden and metastasis to lungs.

CONCLUSIONS

Our results indicate that PKC potentiates tumor metastasis to the bone by potentiating translation increase and can be putatively inhibited by pharmacological inhibition.

Cell Signaling in Neuronal Stem Cells

The defining characteristic of neural stem cells (NSCs) is their ability to multiply through symmetric divisions and proliferation, and differentiation by asymmetric divisions, thus giving rise to different types of cells of the central nervous system (CNS). A strict temporal space control of the NSC differentiation is necessary, because its alterations are associated with neurological dysfunctions and, in some cases, death. This work reviews the current state of the molecular mechanisms that regulate the transcription in NSCs, organized according to whether the origin of the stimulus that triggers the molecular cascade in the CNS is internal (intrinsic factors) or whether it is the result of the microenvironment that surrounds the CNS (extrinsic factors).

Melatonin ameliorates Aβ42 -induced alteration of βAPP-processing secretases via the melatonin receptor through the Pin1/GSK3β/NF-κB pathway in SH-SY5Y cells

Melatonin is involved in the physiological regulation of the β-amyloid precursor protein (βAPP)-cleaving secretases which are responsible for generation of the neurotoxic amyloid beta (Aβ) peptide, one of the hallmarks of Alzheimer's disease (AD) pathology. In this study, we aimed to determine the underlying mechanisms of this regulation under pathological conditions. We establish that melatonin prevents Aβ₄₂ -induced downregulation of a disintegrin and metalloproteinase domain-containing protein 10 (ADAM10) as well as upregulation of β-site APP-cleaving enzyme 1 (BACE1) and presenilin 1 (PS1) in SH-SY5Y cell cultures. We also demonstrate that the intrinsic mechanisms of the observed effects occurred via regulation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and glycogen synthase kinase (GSK)-3β as melatonin reversed Aβ₄₂ -induced upregulation and nuclear translocation of NF-κBp65 as well as activation of GSK3β via its receptor activation. Furthermore, specific blocking of the NF-κB and GSK3β pathways partially abrogated the Aβ₄₂ -induced reduction in the BACE1 and PS1 levels. In addition, GSK3β blockage affected α-secretase cleavage and modulated nuclear translocation of NF-κB. Importantly, our study for the first time shows that peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) is a crucial target of melatonin. The compromised levels and/or genetic variation of Pin1 are associated with age-dependent tau and Aβ pathologies and neuronal degeneration. Interestingly, melatonin alleviated the Aβ₄₂ -induced reduction of nuclear Pin1 levels and preserved the functional integrity of this isomerase. Our findings illustrate that melatonin attenuates Aβ₄₂ -induced alterations of βAPP-cleaving secretases possibly via the Pin1/GSK3β/NF-κB pathway.

Docosahexaenoic acid inhibits 12-O-tetradecanoylphorbol-13- acetate-induced fascin-1-dependent breast cancer cell migration by suppressing the PKCδ- and Wnt-1/β-catenin-mediated pathways

Fascin-1, an actin-bundling protein, plays an important role in cancer cell migration and invasion; however, the underlying mechanism remains unclear. On the basis of a 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced cell migration model, it was shown that TPA increased fascin-1 mRNA and protein expression and fascin-1-dependent cell migration. TPA dose- and time-dependently increased PKCδ and STAT3α activation and GSK3β phosphorylation; up-regulated Wnt-1, β-catenin, and STAT3α expression; and increased the nuclear translocation of β-catenin and STAT3α. Rottlerin, a PKCδ inhibitor, abrogated the increases in STAT3α activation and β-catenin and fascin-1 expression. WP1066, a STAT3 inhibitor, suppressed TPA-induced STAT3α DNA binding activity and β-catenin expression. Knockdown of β-catenin attenuated TPA-induced fascin-1 and STAT3α expression as well as cell migration. In addition to MCF-7, migration of Hs578T breast cancer cells was inhibited by silencing fascin-1, β-catenin, and STAT3α expression as well. TPA also induced Wnt-1 expression and secretion, and blocking Wnt-1 signaling abrogated β-catenin induction. DHA pretreatment attenuated TPA-induced cell migration, PKCδ and STAT3α activation, GSK3β phosphorylation, and Wnt-1, β-catenin, STAT3α, and fascin-1 expression. Our results demonstrated that TPA-induced migration is likely associated with the PKCδ and Wnt-1 pathways, which lead to STAT3α activation, GSK3β inactivation, and β-catenin increase and up-regulation of fascin-1 expression. Moreover, the anti-metastatic potential of DHA is partly attributed to its suppression of TPA-activated PKCδ and Wnt-1 signaling.

Lentiviral Modulation of Wnt/β-Catenin Signaling Affects In Vivo LTP

Wnt signaling is involved in hippocampal development and synaptogenesis. Numerous recent studies have been focused on the role of Wnt ligands in the regulation of synaptic plasticity. Inhibitors and activators of canonical Wnt signaling were demonstrated to decrease or increase, respectively, in vitro long-term potentiation (LTP) maintenance in hippocampal slices (Chen et al. in J Biol Chem 281:11910-11916, 2006; Vargas et al. in J Neurosci 34:2191-2202, 2014, Vargas et al. in Exp Neurol 264:14-25, 2015). Using lentiviral approach to down- and up-regulate the canonical Wnt signaling, we explored whether Wnt/β-catenin signaling is critical for the in vivo LTP. Chronic suppression of Wnt signaling induced an impairment of in vivo LTP expression 14 days after lentiviral suspension injection, while overexpression of Wnt3 was associated with a transient enhancement of in vivo LTP magnitude. Both effects were related to the early phase LTP and did not affect LTP maintenance. A loss-of-function study demonstrated decreased initial paired pulse facilitation ratio, β-catenin, and phGSK-3β levels. A gain-of-function study revealed not only an increase in PSD-95, β-catenin, and Cyclin D1 protein levels, but also a reduced phGSK-3β level and enhanced GSK-3β kinase activity. These results suggest a presynaptic dysfunction predominantly underlying LTP impairment while postsynaptic modifications are primarily involved in transient LTP amplification. This study is the first demonstration of the involvement of Wnt/β-catenin signaling in synaptic plasticity regulation in an in vivo LTP model.

Wnt signaling and podocyte dysfunction in diabetic nephropathy

Nephropathy is a major microvascular complication of diabetes mellitus and often leads to terminal renal failure in addition to contributing significantly to cardiovascular morbidity and mortality. Despites continuous advances, the pathogenesis of diabetic nephropathy remains poorly understood. Recent studies have underscored the significance of structural and functional changes in podocytes in the development and progression of diabetic nephropathy. The role of podocytes in health and diabetic nephropathy and abnormalities including podocyte hypertrophy, effacement, and apoptosis, and a detailed discussion on the role played by the Wnt-β-catenin signaling pathway in podocyte injury and dysfunction are the focus of this review. In addition, the role played by Wnt signaling in mediating the effects of known therapeutic strategies for diabetic nephropathy is also discussed.

Potential lung carcinogenicity induced by chronic exposure to PM2.5 in the rat

Exposure to fine particulate matter (PM_2.5) may increase lung cancer risk, but the underlying mechanisms are poorly understood. This study explored the potential carcinogenicity in rat lung induced by chronic exposure to PM_2.5. Adult male rats (200-220 g) were treated with PM_2.5 (10 mg/kg body weight) by tracheal perfusion once per week for 1 year; the rats were killed, and expression of tumor markers (carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), squamous cell carcinoma antigen (SCCA)), cancer-related genes, and pathological changes were detected. Chronic treatment with PM_2.5 significantly increased SCCA and NSE expression in rat lung tissue and serum. Damaged lung tissue structure was observed by hematoxylin and eosin staining. Although no evidence of tumors was detected, the Wnt/β-catenin signaling, epithelial-mesenchymal transition, vascular endothelial growth factor, and epidermal growth factor receptor pathways were all activated or overexpressed and likely involved in the potential carcinogenicity in the rat model. Additionally, abnormal expression of the proto-oncogenes c-Myc and K-Ras and tumor suppressor p53 can be seen in lung tissue induced by PM_2.5 exposure. Chronic exposure to PM_2.5 has the potential to be carcinogenic in rat lung.

In Vitro Human Umbilical Vein Endothelial Cells Response to Ionic Dissolution Products from Lithium-Containing 45S5 Bioactive Glass

Since lithium (Li⁺) plays roles in angiogenesis, the localized and controlled release of Li⁺ ions from bioactive glasses (BGs) represents a promising alternative therapy for the regeneration and repair of tissues with a high degree of vascularization. Here, microparticles from a base 45S5 BG composition containing (wt %) 45% SiO₂, 24.5% Na₂O, 24.5% CaO, and 6% P₂O₅, in which Na₂O was partially substituted by 5% Li₂O (45S5.5Li), were obtained. The results demonstrate that human umbilical vein endothelial cells (HUVECs) have greater migratory and proliferative response and ability to form tubules in vitro after stimulation with the ionic dissolution products (IDPs) of the 45S5.5Li BG. The results also show the activation of the canonical Wnt/β-catenin pathway and the increase in expression of proangiogenic cytokines insulin like growth factor 1 (IGF1) and transforming growth factor beta (TGFβ). We conclude that the IDPs of 45S5.5Li BG would act as useful inorganic agents to improve tissue repair and regeneration, ultimately stimulating HUVECs behavior in the absence of exogenous growth factors.

In-Depth Proteomic Analysis of the Hippocampus in a Rat Model after Cerebral Ischaemic Injury and Repair by Danhong Injection (DHI)

Stroke is the second most common cause of death worldwide. A systematic description and characterization of the strokes and the effects induced in the hippocampus have not been performed so far. Here, we analysed the protein expression in the hippocampus 24 h after cerebral ischaemic injury and repair. Drug intervention using Danhong injection (DHI), which has been reported to have good therapeutic effects in a clinical setting, was selected for our study of cerebral ischaemia repair in rat models. A larger proteome dataset and total 4091 unique proteins were confidently identified in three biological replicates by combining tissue extraction for rat hippocampus and LC-MS/MS analysis. A label-free approach was then used to quantify the differences among the four experimental groups (Naive, Sham, middle cerebral artery occlusion (MCAO) and MCAO + DHI groups) and showed that about 2500 proteins on average were quantified in each of the experiment group. Bioinformatics analysis revealed that in total 280 unique proteins identified above were differentially expressed (P < 0.05). By combining the subcellular localization, hierarchical clustering and pathway information with the results from injury and repair phase, 12 significant expressed proteins were chosen and verified with respect to their potential as candidates for cerebral ischaemic injury by Western blot. The primary three signalling pathways of the candidates related may be involved in molecular mechanisms related to cerebral ischaemic injury. In addition, a glycogen synthase kinase-3β (Gsk-3β) inhibitor of the candidates with the best corresponding expression trends between western blotting (WB) and label-free quantitative results were chosen for further validation. The results of Western blot analysis of protein expression and 2,3,5- chloride three phenyl tetrazole (TTC) staining of rat brains showed that DHI treatment and Gsk-3β inhibitor are both able to confer protection against ischaemic injury in rat MCAO model. The observations of the present study provide a novel understanding regarding the regulatory mechanism of cerebral ischaemic injury.

The neurotoxicity of amyloid β-protein oligomers is reversible in a primary neuron model

Alzheimer’s disease (AD) is characterized by the accumulation of extracellular amyloid β-protein (Aβ) and intracellular hyperphosphorylated tau proteins. Recent evidence suggests that soluble Aβ oligomers elicit neurotoxicity and synaptotoxicity, including tau abnormalities, and play an initiating role in the development of AD pathology. In this study, we focused on the unclarified issue of whether the neurotoxicity of Aβ oligomers is a reversible process. Using a primary neuron culture model, we examined whether the neurotoxic effects induced by 2-day treatment with Aβ42 oligomers (Aβ-O) are reversible during a subsequent 2-day withdrawal period. Aβ-O treatment resulted in activation of caspase-3 and eIF2α, effects that were considerably attenuated following Aβ-O removal. Immunocytochemical analyses revealed that Aβ-O induced aberrant phosphorylation and caspase-mediated cleavage of tau, both of which were mostly reversed by Aβ-O removal. Furthermore, Aβ-O caused intraneuronal dislocation of β-catenin protein and a reduction in its levels, and these alterations were partially reversed upon Aβ-O withdrawal. The dislocation of β-catenin appeared to reflect synaptic disorganization. These findings indicate that removal of extracellular Aβ-O can fully or partially reverse Aβ-O-induced neurotoxic alterations in our neuron model. Accordingly, we propose that the induction of neurotoxicity by Aβ oligomers is a reversible process, which has important implications for the development of AD therapies.

Novel Non-phosphorylated Serine 9/21 GSK3β/α Antibodies: Expanding the Tools for Studying GSK3 Regulation

Glycogen synthase kinase 3 (GSK3) β and α are serine/threonine kinases involved in many biological processes. A primary mechanism of GSK3 activity regulation is phosphorylation of N-terminal serine (S) residues (S9 in GSK3β, S21 in GSK3α). Phosphorylation is inhibitory to GSK3 kinase activity because the phosphorylated N-terminus acts as a competitive inhibitor for primed substrates. Despite widespread interest in GSK3 across most fields of biology, the research community does not have reagents that specifically react with nonphosphoS9/21 GSK3β/α (the so-called "active" form). Here, we describe two novel monoclonal antibodies that specifically react with nonphosphoS9/21 GSK3β/α in multiple species (human, mouse, and rat). One of the antibodies is specific for nonphospho-S9 GSK3β (clone 12B2) and one for nonphospho-S9/21 GSK3β/α (clone 15C2). These reagents were validated for specificity and reactivity in several biochemical and immunochemical assays, and they show linear detection of nonphosphoS GSK3. Finally, these reagents provide significant advantages in studying GSK3β regulation. We used both antibodies to study the regulation of S9 phosphorylation by Akt and protein phosphatases. We used 12B2 (due to its specificity for GSK3β) and to demonstrate that protein phosphatase inhibition reduces nonphospho-S9 GSK3β levels and lowers kinase activity within cells. The ability to use the same reagent across biochemical, immunohistological and kinase activity assays provides a powerful approach for studying serine-dependent regulation of GSK3β/α.

Neuronal NOS Induces Neuronal Differentiation Through a PKCα-Dependent GSK3β Inactivation Pathway in Hippocampal Neural Progenitor Cells

We investigated the role of neuronal nitric oxide synthase (nNOS) in the neuronal differentiation of neural progenitor cells (NPCs) from hippocampi of E16.5 rat embryos. The production of nitric oxide (NO) and nNOS expression increased markedly during neuronal differentiation as did the expression of neurotrophin-3 (NT3), neurotrophin-4/5 (NT 4/5), and synapsin I. nNOS siRNA or the nNOS inhibitor, 7-nitroindazole (7-NI), decreased expression of the neurotrophins and synapsin I, and suppressed neurite outgrowth. These results suggest that nNOS plays a critical role in neuronal differentiation of hippocampal NPCs. nNOS-mediated neuronal differentiation is controlled by calcineurin since cyclosporin A (CsA), a calcineurin inhibitor, decreased nNOS activation and NO production, and inhibited neurite outgrowth. We found that inactivation of glycogen synthase kinase-3 beta (GSK3β) resulting from activation of protein kinase C alpha (PKCα) is involved in the nNOS-mediated neuronal differentiation. Moreover, lithium chloride (LiCl), a GSK3β inhibitor, increased neuronal differentiation by inhibiting the proliferation of NPCs. Taken together, these results suggest that neuronal differentiation is dependent on calcineurin-mediated activation of nNOS; this induces PKCα-dependent inactivation of GSK3β, which leads to inhibition of the proliferation of hippocampal NPCs.

Inositol depletion, GSK3 inhibition and bipolar disorder

Valproic acid and lithium are widely used to treat bipolar disorder, a severe illness characterized by cycles of mania and depression. However, their efficacy is limited, and treatment is often accompanied by serious side effects. The therapeutic mechanisms of these drugs are not understood, hampering the development of more effective treatments. Among the plethora of biochemical effects of the drugs, those that are common to both may be more related to therapeutic efficacy. Two common outcomes include inositol depletion and GSK3 inhibition, which have been proposed to explain the efficacy of both valproic acid and lithium. Here, we discuss the inositol depletion and GSK3 inhibition hypotheses, and introduce a unified model suggesting that inositol depletion and GSK3 inhibition are inter-related.

Glycogen Synthase Kinase 3β Is Positively Regulated by Protein Kinase Cζ-Mediated Phosphorylation Induced by Wnt Agonists

The molecular events that drive Wnt-induced regulation of glycogen synthase kinase 3β (GSK-3β) activity are poorly defined. In this study, we found that protein kinase Cζ (PKCζ) and GSK-3β interact mainly in colon cancer cells. Wnt stimulation induced a rapid GSK-3β redistribution from the cytoplasm to the nuclei in malignant cells and a transient PKC-mediated phosphorylation of GSK-3β at a different site from serine 9. In addition, while Wnt treatment induced a decrease in PKC-mediated phosphorylation of GSK-3β in nonmalignant cells, in malignant cells, this phosphorylation was increased. Pharmacological inhibition and small interfering RNA (siRNA)-mediated silencing of PKCζ abolished all of these effects, but unexpectedly, it also abolished the constitutive basal activity of GSK-3β. In vitro activity assays demonstrated that GSK-3β phosphorylation mediated by PKCζ enhanced GSK-3β activity. We mapped Ser147 of GSK-3β as the site phosphorylated by PKCζ, i.e., its mutation into alanine abolished GSK-3β activity, resulting in β-catenin stabilization and increased transcriptional activity, whereas phosphomimetic replacement of Ser147 by glutamic acid maintained GSK-3β basal activity. Thus, we found that PKCζ phosphorylates GSK-3β at Ser147 to maintain its constitutive activity in resting cells and that Wnt stimulation modifies the phosphorylation of Ser147 to regulate GSK-3β activity in opposite manners in normal and malignant colon cells.

PBA regulates neurogenesis and cognition dysfunction after repeated electroconvulsive shock in a rat model

Electroconvulsive therapy (ECT) was widely used to treat the refractory depression. But ECT led to the cognitive deficits plaguing the depression patients. The underlying mechanisms of the cognitive deficits remain elusive. Repeated electroconvulsive shock (rECS) was used to simulate ECT and explore the mechanisms of ECT during the animal studies. Previous studies showed rECS could lead to neurogenesis and cognitive impairment. But it was well known that neurogenesis could improve the cognition. So these suggested that the mechanism of the cognitive deficit after rECS was very complex. In present study, we explored the probable mechanisms of the cognitive deficit after rECS from neurogenesis aspect. We found the cognitive deficit was reversible and neurogenesis could bring a long-term beneficial effect on cognition. Astrogliosis and NR1 down-regulation probably participated in the reversible cognitive deficits after rECS. Phenylbutyric acid (PBA), generally as an agent to investigate the roles of histone acetylation, could prevent the reversible cognitive dysfunction, but PBA could diminish the long-term effect of enhanced cognition by rECS. These suggested that ECT could possibly bring the long-term beneficial cognitive effect by regulating neurogenesis.

Osthole promotes neuronal differentiation and inhibits apoptosis via Wnt/β-catenin signaling in an Alzheimer's disease model

Neurogenesis is the process by which neural stem cells (NSCs) proliferate and differentiate into neurons. This is diminished in several neurodegenerative disorders such as Alzheimer's disease (AD), which is characterized by the deposition of amyloid (A)β peptides and neuronal loss. Stimulating NSCs to replace lost neurons is therefore a promising approach for AD treatment. Our previous study demonstrated that osthole modulates NSC proliferation and differentiation, and may reduce Aβ protein expression in nerve cells. Here we investigated the mechanism underlying the effects of osthole on NSCs. We found that osthole enhances NSC proliferation and neuronal differentiation while suppressing apoptosis, effects that were exerted via activation of Wnt/β-catenin signaling. These results provide evidence that osthole can potentially be used as a therapeutic agent in the treatment of AD and other neurodegenerative disorders.

Regulation of β-catenin transcription activity by leupaxin in hepatocellular carcinoma

In human cancers, β-catenin is accumulated in the nucleus and activates mRNA transcription of many oncogenic genes, such as cyclin D1 and c-myc. However, the mechanism of β-catenin-mediated transcriptional activation remains largely unknown. In the present study, we identified leupaxin, an adaptor protein sharing homology with the focal adhesion protein, as a novel coactivator for β-catenin in human hepatocellular carcinoma (HCC). We show that leupaxin could interact with β-catenin and enhance its transcriptional activity through recruitment of coactivator complex, including steroid receptor coactivator 1 (SRC-1) and P300. As a result, leupaxin regulates HCC cell proliferation and cell-cycle progression in the presence of intact Wnt/β-catenin signaling. Furthermore, leupaxin is overexpressed in HCC tissues and correlated with mRNA levels of cyclin D1 and c-myc. Therefore, this is the first demonstration of a role for the leupaxin in the regulation of HCC progression, at least in part, by enhancing β-catenin transcription activity.

Wnt-5a prevents Aβ-induced deficits in long-term potentiation and spatial memory in rats

Although the neurotoxicity of amyloid β (Aβ) protein in Alzheimer's disease (AD) has been reported widely, the exact molecular mechanism underlying the Aβ-induced synaptic dysfunction and memory impairment remains largely unclear. Growing evidence indicates that wingless-type (Wnt) signaling plays an important role in neuronal development, synapse formation and synaptic plasticity. In the present study, we investigated the neuroprotective action of Wnt-5a against the synaptic damage and memory deficit induced by Aβ25-35 by using in vivo electrophysiological recording and Morris water maze (MWM) test. We found that intracerebroventricular (i.c.v.) injection of Aβ25-35 alone did not affect the baseline field excitatory postsynaptic potentials (fEPSPs) and the paired-pulse facilitation (PPF) in the hippocampal CA1 region of rats, but significantly suppressed high frequency stimulation (HFS) induced long-term potentiation (LTP); pretreatment with Wnt-5a prevented the Aβ25-35-induced suppression of hippocampal LTP in a dose-dependent manner; soluble Frizzled-related protein (sFRP), a specific Wnt antagonist, effectively attenuated the protective effects of Wnt-5a. In MWM test, Aβ25-35 alone significantly disrupted spatial learning and memory ability of rats, while pretreatment with Wnt-5a effectively prevented the impairments induced by Aβ25-35. These results in the present study demonstrated for the first time the neuroprotective effects of Wnt-5a against Aβ-induced in vivo synaptic plasticity impairment and memory disorder, suggesting that Wnt signaling pathway is one of the important targets of Aβ neurotoxicity and Wnt-5a might be used as one of the putative candidates for the therapeutic intervention of AD.

Novel cancer chemotherapy hits by molecular topology: dual Akt and Beta-catenin inhibitors

Background and Purpose

Colorectal and prostate cancers are two of the most common types and cause of a high rate of deaths worldwide. Therefore, any strategy to stop or at least slacken the development and progression of malignant cells is an important therapeutic choice. The aim of the present work is the identification of novel cancer chemotherapy agents. Nowadays, many different drug discovery approaches are available, but this paper focuses on Molecular Topology, which has already demonstrated its extraordinary efficacy in this field, particularly in the identification of new hit and lead compounds against cancer. This methodology uses the graph theoretical formalism to numerically characterize molecular structures through the so called topological indices. Once obtained a specific framework, it allows the construction of complex mathematical models that can be used to predict physical, chemical or biological properties of compounds. In addition, Molecular Topology is highly efficient in selecting and designing new hit and lead drugs. According to the aforementioned, Molecular Topology has been applied here for the construction of specific Akt/mTOR and β-catenin inhibition mathematical models in order to identify and select novel antitumor agents.

Experimental Approach

Based on the results obtained by the selected mathematical models, six novel potential inhibitors of the Akt/mTOR and β-catenin pathways were identified. These compounds were then tested in vitro to confirm their biological activity.

Conclusion and Implications

Five of the selected compounds, CAS n° 256378-54-8 (Inhibitor n°1), 663203-38-1 (Inhibitor n°2), 247079-73-8 (Inhibitor n°3), 689769-86-6 (Inhibitor n°4) and 431925-096 (Inhibitor n°6) gave positive responses and resulted to be active for Akt/mTOR and/or β-catenin inhibition. This study confirms once again the Molecular Topology’s reliability and efficacy to find out novel drugs in the field of cancer.

Extracellular superoxide dismutase regulates the expression of small gtpase regulatory proteins GEFs, GAPs, and GDI

Extracellular superoxide dismutase (SOD3), which catalyzes the dismutation of superoxide anions to hydrogen peroxide at the cell membranes, regulates the cellular growth in a dose-dependent manner. This enzyme induces primary cell proliferation and immortalization at low expression levels whereas it activates cancer barrier signaling through the p53-p21 pathway at high expression levels, causing growth arrest, senescence, and apoptosis. Because previous reports suggested that the SOD3–induced reduction in the rates of cellular growth and migration also occurred in the absence of functional p53 signaling, in the current study we investigated the SOD3-induced growth-suppressive mechanisms in anaplastic thyroid cancer cells. Based on our data, the robust over-expression of SOD3 increased the level of phosphorylation of the EGFR, ERBB2, RYK, ALK, FLT3, and EPHA10 receptor tyrosine kinases with the consequent downstream activation of the SRC, FYN, YES, HCK, and LYN kinases. However, pull-down experiments focusing on the small GTPase RAS, RAC, CDC42, and RHO revealed a reduced level of growth and migration signal transduction, such as the lack of stimulation of the mitogen pathway, in the SOD3 over-expressing cells, which was confirmed by MEK1/2 and ERK1/2 Western blotting analysis. Interestingly, the mRNA expression analyses indicated that SOD3 regulated the expression of guanine nucleotide-exchange factors (RHO GEF16, RAL GEF RGL1), GTPase-activating proteins (ARFGAP ADAP2, RAS GAP RASAL1, RGS4), and a Rho guanine nucleotide-disassociation inhibitor (RHO GDI 2) in a dose dependent manner, thus controlling signaling through the small G protein GTPases. Therefore, our current data may suggest the occurrence of dose-dependent SOD3–driven control of the GTP loading of small G proteins indicating a novel growth regulatory mechanism of this enzyme.

GSK-3β suppresses the proliferation of rat hepatic oval cells through modulating Wnt/β-catenin signaling pathway

AIM

Glycogen synthase kinase 3β (GSK-3β) plays a crucial role in hepatic biology, including liver development, regeneration, proliferation and carcinogenesis. In this study we investigated the role of GSK-3β in regulation of growth of hepatic oval cells in vitro and in liver regeneration in partially hepatectomized rats.

METHODS

WB-F344 cells, the rat hepatic stem-like epithelial cells, were used as representative of oval cells. Cell viability was examined using a WST-8 assay. The cells were transfected with a recombinant lentivirus expressing siRNA against GSK-3β (GSK-3βRNAiLV) or a lentivirus that overexpressed GSK-3β (GC-GSK-3βLV). Adult rats underwent partial (70%) hepatectomy, and liver weight and femur length were measured at d 7 after the surgery. The expression of GSK-3β, phospho-Ser9-GSK-3β, β-catenin and cyclin D1 was examined with immunoblotting assays or immunohistochemistry.

RESULTS

Treatment of WB-F344 cells with the GSK-3β inhibitor SB216763 (5 and 10 μmol/L) dose-dependently increased the levels of phospho-Ser9-GSK-3β, but not the levels of total GSK-3β, and promoted the cell proliferation. Knockout of GSK-3β with GSK-3βRNAiLV increased the cell proliferation, whereas overexpression of GSK-3β with GC-GSK-3βLV decreased the proliferation. Both SB216763 and GSK-3βRNAiLV significantly increased the levels of β-catenin and cyclin D1 in the cells, whereas GSK-3β overexpression decreased their levels. In rats with a partial hepatectomy, administration of SB216763 (2 mg/kg, ip) significantly increased the number of oval cells, the levels of phospho-Ser9-GSK-3β, β-catenin and cyclin D1 in liver, as well as the ratio of liver weight to femur length at d 7 after the surgery.

CONCLUSION

GSK-3β suppresses the proliferation of hepatic oval cells by modulating the Wnt/β-catenin signaling pathway.

Region-specific dysregulation of glycogen synthase kinase-3β and β-catenin in the postmortem brains of subjects with bipolar disorder and schizophrenia

OBJECTIVES

There is both direct and indirect evidence suggesting abnormalities of glycogen synthase kinase (GSK)-3β and β-catenin, two important components of the Wingless-type (Wnt) signaling pathway, in the pathophysiology of bipolar illness and possibly schizophrenia (SZ). In order to further clarify the role of the Wnt signaling pathway in the pathophysiology of bipolar disorder (BP) and SZ, we studied GSK-3β and β-catenin in the postmortem brains of subjects with these disorders.

METHODS

We determined the protein expression of GSK-3β, phosphorylated form at serine 9 position (pGSK-3-ser-9), and β-catenin using the western blot technique, and mRNA using the quantitative polymerase chain reaction (qPCR) method, in the dorsolateral prefrontal cortex (DLPFC), cingulate gyrus (CG), and temporal cortex (TEMP) obtained from 19 subjects with BP, 20 subjects with SZ, and 20 normal control (NC) subjects.

RESULTS

We found that the protein expression of GSK-3β, pGSK-3β-ser-9, and β-catenin was significantly decreased in the DLPFC and TEMP, but not in the CG, of subjects with BP compared with NC subjects. The mRNA expression of GSK-3β and β-catenin was significantly decreased in the DLPFC and TEMP, but not in the CG, of subjects with BP compared with NC subjects. There were no significant differences in the protein or mRNA expression of GSK-3β, pGSK-3β-ser-9, or β-catenin between subjects with SZ and NC subjects in any of the brain areas studied.

CONCLUSIONS

These studies show region-specific abnormalities of both protein and mRNA expression of GSK-3β and β-catenin in postmortem brains of subjects with BP but not subjects with SZ. Thus, abnormalities of the Wnt signaling pathway may be associated with the pathophysiology of bipolar illness.

Antiproliferative effect of the methanol extract from the roots of Petasites japonicus on Hep3B hepatocellular carcinoma cells in vitro and in vivo

Traditional medicinal plants have been used in the treatment of various diseases for centuries. A number of plant-derived compounds have been proposed as anticancer agents and are currently undergoing medical development. Petasites japonicus (PJ), also known as Butterbur, is a herb cultivated in East Asia that is used as a traditional herbal medicine. The aim of the present study was to investigate whether a methanol extract of PJ demonstrated anticancer activity against Hep3B hepatocellular carcinoma (HCC) cells. The anticancer property and underlying mechanism of the extract were evaluated by assessing the effect on cell viability, nuclear morphology and the expression of phosphorylated (p)-mTOR, p-Akt, β-catenin and p-glycogen synthase kinase-3β, which are markers for cancer cell proliferation and metastasis. These results were obtained by the MTT assay, fluorescence microscopy and Western blot analysis. The methanol extract of PJ was shown to decrease the cell viability in a concentration-dependent manner. In addition, the methanol extract of PJ was found to inhibit the growth of Hep3B HCC cells through inhibiting the Akt/mTOR and Wnt signaling pathways. These results suggest that the methanol extract of PJ exerts an anticancer effect on Hep3B HCC cells.

Canonical Wnt signaling activity in early stages of chick lung development

Wnt signaling pathway is an essential player during vertebrate embryonic development which has been associated with several developmental processes such as gastrulation, body axis formation and morphogenesis of numerous organs, namely the lung. Wnt proteins act through specific transmembrane receptors, which activate intracellular pathways that regulate cellular processes such as cell proliferation, differentiation and death. Morphogenesis of the fetal lung depends on epithelial-mesenchymal interactions that are governed by several growth and transcription factors that regulate cell proliferation, fate, migration and differentiation. This process is controlled by different signaling pathways such as FGF, Shh and Wnt among others. Wnt signaling is recognized as a key molecular player in mammalian pulmonary development but little is known about its function in avian lung development. The present work characterizes, for the first time, the expression pattern of several Wnt signaling members, such as wnt-1, wnt-2b, wnt-3a, wnt-5a, wnt-7b, wnt-8b, wnt-9a, lrp5, lrp6, sfrp1, dkk1, β-catenin and axin2 at early stages of chick lung development. In general, their expression is similar to their mammalian counterparts. By assessing protein expression levels of active/total β-catenin and phospho-LRP6/LRP6 it is revealed that canonical Wnt signaling is active in this embryonic tissue. In vitro inhibition studies were performed in order to evaluate the function of Wnt signaling pathway in lung branching. Lung explants treated with canonical Wnt signaling inhibitors (FH535 and PK115-584) presented an impairment of secondary branch formation after 48 h of culture along with a decrease in axin2 expression levels. Branching analysis confirmed this inhibition. Wnt-FGF crosstalk assessment revealed that this interaction is preserved in the chick lung. This study demonstrates that Wnt signaling is crucial for precise chick lung branching and further supports the avian lung as a good model for branching studies since it recapitulates early mammalian pulmonary development.

Preclinical toxicity of AZD7969: Effects of GSK3β inhibition in adult stem cells

AZD7969 is a potent inhibitor of glycogen synthase kinase 3 (GSK3β), which is a multifunctional serine/threonine kinase that negatively regulates the Wnt/β-catenin signaling pathway. Treatment of rats and dogs with AZD7969 for periods of up to 4 weeks resulted in a number of changes, the most significant of which was a dose-dependent, and treatment-related, increase in proliferation in a number of tissues that was thought to arise from derepression of Wnt/β-catenin signaling in the stem cell compartment. Phenotypically, this resulted in hyperplasia that either maintained normal tissue architecture in the gastrointestinal tract, liver, kidney, and adrenals or effaced normal tissue architecture within the bones, incisor teeth, and femorotibial joint. In addition to these changes, we noted a treatment-related increase in iron loading in the liver and proximal small intestines. This off-target effect was robust, potent, and occurred in both dogs and rats suggesting that AZD7969 might be a useful tool compound to study iron storage disorders in the laboratory.