Notch Signaling Target Genes Research Articles

Synergistic Effects of Ethanol Extract of Allium sativum (Garlic) with DAPT and ATRA on Notch Signaling Targeted Molecular Action on Lung Cancer Cell line (A549)

Background: The activated oncogenic Notch signalling is an emerging target to treat cancer progression and recurrence. Synthetic inhibitors of Notch receptors are in pre-clinical studies. However, the overexpression of Notch signalling molecules at the gene level needs to be regulated to control cancer progression. Objective: We propose that this can be achieved by gene-regulatory drugs in combination with natural phytochemical compounds. Methods: The ethanol extract of Allium sativum alone and in combination with DAPT and ATRA were evaluated for cytotoxicity on A549 cells by MTT and Trypan blue assays. Their effects on Notch 1, Hes 1 and p53 gene expressions were studied by RT-PCR and qPCR. Their inhibition on metastatic invasion of A549 cells was analyzed by in vitro wound scratch assay. The phytochemicals of the extract were identified by GC-MS analysis. Results: Many organosulfur compounds having anti-cancer potency were identified in GC-MS. The combination treatment with 50μg (IC50) of garlic extract exhibited a highly significant (P≤0.01) synergistic inhibitory effect on A549 cell growth and migration. It has also significantly reduced the expression of Notch 1 and Hes 1 oncogenes and enhanced p53 gene expression, compared with the individual treatments. This indicates the synergistic action of the extract on the downregulation of Notch signalling at the mRNA level. Conclusion: Our study results imply that the combination therapies have potent molecular treatment action via down-regulating Notch signaling target genes and upregulating p53 gene expression as an underlying mechanism of inhibitory action on A549 lung cancer cells.

Directing cellular responses in a nanocomposite 3D matrix for tissue regeneration with nanoparticle-mediated drug delivery

Hydrogels play an important role in tissue engineering due to their native extracellular matrix-like characteristics, but they are insufficient in providing the necessary stimuli to support tissue formation. Efforts to integrate bioactive cues directly into hydrogels are hindered by incompatibility with hydrophobic drugs, issues of burst/uncontrolled release, and rapid degradation of the bioactive molecules. Skeletal muscle tissue repair requires internal stimuli and communication between cells for regeneration, and nanocomposite systems offer to improve the therapeutic effects in tissue regeneration. Here, the versatility of mesoporous silica nanoparticles (MSN) was leveraged to formulate a nanoparticle-hydrogel composite and to combine the benefits of controlled delivery of bioactive cues and cellular support. The tunable surface characteristics of MSNs were exploited to optimize homogeneity and intracellular drug delivery in a 3D matrix. Nanocomposite hydrogels formulated with acetylated or succinylated MSNs achieved high homogeneity in 3D distribution, with succinylated MSNs being rapidly internalized and acetylated MSNs exhibiting slower cellular uptake. MSN-hydrogel nanocomposites simultaneously allowed efficient local intracellular delivery of a hydrophobic model drug. To further study the efficiency of directing cell response, a Notch signaling inhibitor (DAPT) was incorporated into succinylated MSNs and incorporated into the hydrogel. MSN-hydrogel nanocomposites effectively downregulated the Notch signaling target genes, and accelerated and maintained the expression of myogenic markers. The current findings demonstrate a proof-of-concept in effective surface engineering strategies for MSN-based nanocomposites, suited for hydrophobic drug delivery in tissue regeneration with guided cues.

FRI022 The Stress-Response Pathways Of NRF2 And Notch Are Upregulated In The Adipocytes But Not In The Immune Cells Of Obese Subjects Adipose Tissue

Abstract Disclosure: D. Chartoumpekis: None. I. Georgakopoulos-Soares: None. Introduction: Obesity is characterized by increased reactive oxygen species (ROS) in adipose tissue. Nrf2 is a transcription factor which regulates antioxidant and cytoprotective genes. ROS react with cysteines of Keap1, the cytoplasmic inhibitor of Nrf2, leading to conformational changes which render Keap1 unable to bind to Nrf2 molecules and lead them to degradation by the proteasome. Thus, Nrf2 accumulates, enters the nucleus and induces the expression of its target genes. Notch signaling is known for its roles in development, cell fate, cell differentiation, apoptosis and proliferation. Notch is a family of intermembrane receptors. The extracellular part of Notch interacts with a ligand of a neighboring cell and triggers two successive proteolytic cleavages by proteases. This permits the release of Notch Intracellular Domain (NICD) to enter the nucleus and induce the expression of target genes. ROS have been recently shown to activate the metalloproteases ADAM 10/17 and facilitate the cleavage of NICD and thus the activation of Notch pathway. A bidirectional transcriptional regulation of Nrf2-Notch has also been described. Hence, both Nrf2 and Notch can be considered as pathways that respond to oxidative stress. Hypothesis: We hypothesized that Nrf2 and Notch pathways are upregulated in the adipose tissue of obese subjects in response to increased ROS levels. Methods: We identified publicly available (series GSE176171) single-cell RNA sequencing data from adipose tissue from humans with BMI<25 kg/m2 (normal weight) or BMI>30 kg/m2 (obese) and from C57BL6 mice fed a high-fat diet (60% kcal fat) or a normal chow diet (6.4% kcal fat) for 13 weeks. R studio read RDS and fetchdata functions were employed to analyze the data in the different cell types of adipose tissue (vascular, immune, mesothelial cells and adipocytes). Results: An at least a 2-fold increase was seen in the RNA levels of several cytoprotective genes (such as NQO1, TXNRD1, GCLC, HMOX1, GSTA4), that are known to be regulated by Nrf2, in adipocytes from obese humans compared to the normal weight ones. Similar changes were found in the murine adipocytes of obese subjects. Interestingly, no significant differences were detected in these gene sets in immune cells from the mouse and human adipose tissue between lean and obese individuals. Notch 1-3 RNA was also found increased at least 2-fold in human adipocytes of obese patients while only Notch3 RNA was increased in adipocytes of obese mice. A common target gene of Notch signaling, Hes1, showed increased expression in both human (2-fold) and murine (4-fold) adipocytes of obese subjects. These changes were not seen in the immune cells of both species. Conclusions: This increased Nrf2 and Notch signaling in adipocytes in the obese state warrants further investigation as it may play roles in the homeostasis and the capacity of the adipose tissue and in the resulting metabolic phenotype. Presentation: Friday, June 16, 2023

Significance of NOTCH1 Expression in the Progression of Human Lung and Colorectal Cancers.

Lung and colorectal cancers are the most common types of cancer characterized by a poor prognosis and a high mortality rate. Mutations in the genes encoding components of the main intra- and extracellular signaling pathways, in particular the NOTCH1 gene (Notch1, a member of the Notch family of receptors), play one of the key roles in progression of these malignancies. Notch signaling is involved in maintaining homeostasis of the intestinal epithelium and structural and functional lung elements. Therefore, it is not surprising that the constitutive activity and hyperactivity of Notch signaling due to somatic mutations in genes coding for the products directly involved into its activation, could lead to the progression of these cancer types. The aim of our study was to investigate how the NOTCH1 downregulation via RNA interference (RNAi) affects the phenotype, characteristics, and Notch-dependent signaling of human A549 lung and HCT116 colorectal carcinoma cells. Several small harpin RNAs (shRNAs) were selected using the bioinformatic analysis and tested for their ability to suppress the NOTCH1 expression. The most efficient one was used to produce the A549 and HCT116 cells with NOTCH1 knockdown. The obtained cell lines demonstrated decreased proliferation rates, reduced colony-forming capacity under adhesive conditions, and decreased migration activity in a Boyden chamber. The NOTCH1 knockdown also significantly decreased expression of some Notch signaling target genes potentially involved in the acquisition and maintenance of more invasive and malignant cell phenotype. In vivo experiments in immunodeficient athymic female Balb/c nu/nu mice confirmed the results obtained in vitro: the NOTCH1 inhibition decreased the growth rates of the subcutaneous xenografts formed by A549 and HCT116 tumor cells. Therefore, downregulation of the gene encoding the Notch1 receptor potentially reduces malignant characteristics of human lung and colorectal carcinoma cells.

Histone deacetylase inhibition promotes regenerative neurogenesis after stab wound injury in the adult zebrafish optic tectum

The central nervous system (CNS) of adult zebrafish is capable of recovering from injury, unlike the CNS of mammals such as humans or rodents. Previously, we established a stab wound injury model of the optic tectum (OT) in the adult zebrafish and showed that the radial glial cells (RG) proliferation and neuronal differentiation contributes to OT regeneration. In the present study, we analyzed the function of histone deacetylases (HDACs) as potential regulators of OT regeneration. The expression of both hdac1 and hdac3 was found to be significantly decreased in the injured OT. In order to analyze the roles of HDACs in RG proliferation and differentiation after injury, we performed pharmacological experiments using the HDAC inhibitor trichostatin A. We found that HDAC inhibition after stab wound injury suppressed RG proliferation but promoted neuronal differentiation. Moreover, HDAC inhibition suppressed the injury-induced decline in expression of Notch signaling target genes, her4.1 and her6 after OT injury. These results suggest that HDACs regulate regenerative neurogenesis through changes in Notch target gene expression by histone deacetylation. HDACs and histone acetylation are promising molecular targets for neuronal regeneration and further studies about the molecular mechanisms behind the regulation of regeneration by histone acetylation are necessary.

CHK1/2 Inhibitor Prexasertib Suppresses NOTCH Signaling and Enhances Cytotoxicity of Cisplatin and Radiation in Head and Neck Squamous Cell Carcinoma.

Platinum-based chemoradiotherapy is a mainstay of organ-preserving therapy for patients with head and neck squamous cell carcinoma cancer (HNSCC). However, the disease eventually becomes resistant to treatment necessitating new therapies. Checkpoint kinase 1 and 2 (CHK1/2) are serine/threonine kinases that activate cell-cycle checkpoints and serve a critical role in the DNA-damage response (DDR). As resistance to cisplatin and radiation may involve a heightened DDR, we hypothesized that prexasertib, an inhibitor of CHK1/2, may enhance the cytotoxicity induced by cisplatin and irradiation in HNSCC. In this study, we found that combining prexasertib with cisplatin and radiation significantly decreased the in vitro survival fraction in HNSCC cell lines both with and without radiotherapy. Reduced survival was accompanied by inhibition of DNA repair checkpoint activation, which resulted in persistent DNA damage and increased apoptosis. In addition, NanoString analysis with the PanCancer Pathways Panel revealed that prexasertib downregulated NOTCH signaling target genes (NOTCH1, NOTCH2, and NOTCH3) and their associated ligands (JAG1, JAG2, SKP2, MAML2, and DLL1). Prexasertib also reduced NOTCH1, NOTCH3 and HES1 protein expression. Importantly, a significant tumor growth delay was observed in vivo in both human papillomavirus (HPV)-positive UM-SCC47 and HPV-negative UM-SCC1 cell line xenografts treated with prexasertib, cisplatin, and radiotherapy without increased toxicity as measured by mouse body weight. Taken together, prexasertib reduced NOTCH signaling and enhanced the in vitro and in vivo response of HNSCCs to cisplatin and radiation, suggesting combination therapy may increase clinical benefit. A clinical trial has recently completed accrual (NCT02555644).

Salidroside suppresses the metastasis of hepatocellular carcinoma cells by inhibiting the activation of the Notch1 signaling pathway.

Salidroside (SDS) is a phenylpropanoid glycoside isolated from Rhodiola rosea L. It exhibits multiple pharmacological properties in clinical medicine and has been commonly used in traditional Chinese medicine. The present study investigated the inhibitory effects of SDS on tumor invasion and migration, and the expression of metastasis‑related genes in highly metastatic hepatocellular carcinoma (HCC) cells (MHCC97H)invitro. The underlying mechanisms of SDS on the tumor metastasis were also explored. SDS was found to significantly reduce wound closure areas and inhibit cell migration. In addition, SDS markedly inhibited the invasion of these cells into Matrigel‑coated membranes. SDS markedly downregulated the expression of Notch1, Snail, COX‑2, MMP‑2, MMP‑9 genes and upregulated the expression of E‑cadherin in a dose‑dependent manner. Furthermore, SDS inhibited the expression of the Notch signaling target genes, Hey1, Hes1 and Hes5. On the whole, the findings of this study suggest that SDS inhibits HCC cell metastasis by modulating the activity of the Notch1 signaling pathway.

Contribution of NOTCH signaling pathway along with TNF-α in the intestinal inflammation of ulcerative colitis.

The aim of this study was to determine gene expression levels of TNF-α, NOTCH1, and HES1 in patients with UC. Intestinal inflammation and epithelial injury are the leading actors of inflammatory bowel disease (IBD), causing an excessive expression of pro-inflammatory cytokines such as TNF-α. Also, target genes of NOTCH signaling are involved in the regulation of intestinal homeostasis. Previous studies have demonstrated that TNF-α increases in ulcerative colitis (UC) patients, but the relationship between TNF-α and NOTCH signaling pathway in UC etiopathology needs further study. Twelve active UC patients and twelve healthy controls were enrolled in this study. RNA was extracted and the mRNA expression levels of TNF-α, NOTCH1, and HES1 were examined using real-time PCR analyses. Further, transcriptome data deposited in Gene Expression Omnibus (GEO) database were analyzed to detect the differential expression of TNF superfamily and NOTCH1 gene in IBD patients. Finally, the interaction of TNF-α and NOTCH signaling was obtained from The SIGnaling Network Open Resource 2.0 (SIGNOR 2.0) database. The transcription levels of TNF-α, NOTCH1, and HES1 genes were significantly elevated in UC patients compared with control (p < 0.05). In addition, GEO results confirmed our expression results. SIGNOR analysis showed that TNF-α interacts with NOTCH signaling components. Based on our data, we observed that NOTCH1 and HES1 in co-operation of TNF-α, may play an important role in pathogenesis of UC. The members of NOTCH signaling pathway can be ideal candidates to target the therapy of IBD.

Involvement of sonic hedgehog and notch signaling in regenerative neurogenesis in adult zebrafish optic tectum after stab injury.

Unlike humans and other mammals, adult zebrafish have the superior capability to recover from central nervous system (CNS) injury. We previously found that proliferation of radial glia (RG) is induced in response to stab injury in optic tectum and that new neurons are generated from RG after stab injury. However, molecular mechanisms which regulate proliferation and differentiation of RG are not well known. In the present study, we investigated Shh and Notch signaling as potential mechanisms regulating regeneration in the optic tectum of adult zebrafish. We used Shh reporter fish and confirmed that canonical Shh signaling is activated specifically in RG after stab injury. Moreover, we have shown that Shh signaling promotes RG proliferation and suppresses their differentiation into neurons after stab injury. In contrast, Notch signaling was down-regulated after stab injury, indicated by the decrease in the expression level of her4 and her6, a target gene of Notch signaling. We also found that inhibition of Notch signaling after stab injury induced more proliferative RG, but that inhibition of Notch signaling inhibited generation of newborn neurons from RG after stab injury. These results suggest that high level of Notch signaling keeps RG quiescent and that appropriate level of Notch signaling is required for generation of newborn neurons from RG. Under physiological condition, activation of Shh signaling or inhibition of Notch signaling also induced RG proliferation. In adult optic tectum of zebrafish, canonical Shh signaling and Notch signaling play important roles in proliferation and differentiation of RG in physiological and regenerative conditions.

Downregulation of Hes1 expression in experimental biliary atresia and its effects on bile duct structure.

AIMTo analyze the expression and function of the Notch signaling target gene Hes1 in a rhesus rotavirus-induced mouse biliary atresia model.METHODSThe morphologies of biliary epithelial cells in biliary atresia patients and in a mouse model were examined by immunohistochemical staining. Then, the differential expression of Notch signaling pathway-related molecules was investigated. Further, the effects of the siRNA-mediated inhibition of Hes1 expression were examined using a biliary epithelial cell 3D culture system.RESULTSBoth immature (EpCAM+) and mature (CK19+) biliary epithelial cells were detected in the livers of biliary atresia patients without a ductile structure and in the mouse model with a distorted bile duct structure. The hepatic expression of transcripts for most Notch signaling molecules were significantly reduced on day 7 but recovered to normal levels by day 14, except for the target molecule Hes1, which still exhibited lower mRNA and protein levels. Expression of the Hes1 transcriptional co-regulator, RBP-Jκ was also reduced. A 3D gel culture system promoted the maturation of immature biliary epithelial cells, with increased expression of CK19+ cells and the formation of a duct-like structure. The administration of Hes1 siRNA blocked this process. As a result, the cells remained in an immature state, and no duct-like structure was observed.CONCLUSIONOur data indicated that Hes1 might contribute to the maturation and the cellular structure organization of biliary epithelial cells, which provides new insight into understanding the pathology of biliary atresia.

Ketamine Modulates Zic5 Expression via the Notch Signaling Pathway in Neural Crest Induction.

Ketamine is a potent dissociative anesthetic and the most commonly used illicit drug. Many addicts are women at childbearing age. Although ketamine has been extensively studied as a clinical anesthetic, its effects on embryonic development are poorly understood. Here, we applied the Xenopus model to study the effects of ketamine on development. We found that exposure to ketamine from pre-gastrulation (stage 7) to early neural plate (stage 13.5) resulted in disruption of neural crest (NC) derivatives. Ketamine exposure did not affect mesoderm development as indicated by the normal expression of Chordin, Xbra, Wnt8, and Fgf8. However, ketamine treatment significantly inhibited Zic5 and Slug expression at early neural plate stage. Overexpression of Zic5 rescued ketamine-induced Slug inhibition, suggesting the blockage of NC induction was mediated by Zic5. Furthermore, we found Notch signaling was altered by ketamine. Ketamine inhibited the expression of Notch targeted genes including Hes5.2a, Hes5.2b, and ESR1 and ketamine-treated embryos exhibited Notch-deficient somite phenotypes. A 15 bp core binding element upstream of Zic5 was induced by Notch signaling and caused transcriptional activation. These results demonstrated that Zic5 works as a downstream target gene of Notch signaling in Xenopus NC induction. Our study provides a novel teratogenic mechanism whereby ketamine disrupts NC induction via targeting a Notch-Zic5 signaling pathway.

Cell type-specific effects of Notch signaling activation on intervertebral discs: Implications for intervertebral disc degeneration.

Intervertebral disc (IVD) degeneration is the major cause of back pain. Notch signaling is activated in annulus fibrosus (AF) and nucleus pulposus (NP) tissues of degenerated IVDs, and induced by IL1-β and TNF-α in NP cells. However, the role of Notch activatin in the pathogenesis of IVD degeneration is largely unknown. In this study, we overexpressed the Notch1 intracellular domain (NICD1) in AF, NP, and chondrogenic ATDC5 cells via adenoviruses. Overexpression of NICD1 activated transcription of Notch signaling target genes in AF, NP, and ATDC5 cells, and caused cell type-specific effects on expression of matrix anabolic and catabolic genes. Activation of Notch signaling promoted expression of matrix catabolic genes and inhibited expression of matrix anabolic genes in both AF and ATDC5 cells, whereas its activation suppressed expression of matrix catabolic genes (including Mmp3, Mmp13, Adamts4, and Adamts5) and attenuated TNF-α and inflammatory macrophage-induced Mmp13 expression in NP cells. Consistently, sustained activation of Notch1 signaling in postnatal IVDs in mice severely disrupted growth plate and endplate cartilage tissues, but did not overly affect NP tissues. Together, these data indicated that activation of Notch signaling exerted differential and cell type-specific effects in intervertebral discs, and specific Notch signaling regulation may be considered during the treatment of IVD degeneration.

Hey1 functions as a positive regulator of odontogenic differentiation in odontoblast‑lineage cells.

Substantial evidence has indicated that Notch and bone morphogenetic protein (BMP) signaling may regulate odontoblastic differentiation. Hairy/enhancer-of-split related with YRPW motif 1 (Hey1), a downstream target gene of Notch and BMP signaling, is expressed in dental pulp tissues and has been demonstrated to be responsible for osteoblast mineralization. The aim of this study was to investigate the effects of Hey1 on odontoblast differentiation. The results of the study demonstrated that Hey1 expression in odontoblast-lineage cells (OLCs) was upregulated by stimulation of osteoblastic/odontoblastic differentiation medium containing ascorbic acid, β-glycerol phosphate and dexamethasone. Furthermore, stable Hey1-overexpressing cells expressed higher levels of dentin sialophosphoprotein (DSPP) and exhibited higher mineralization capabilities following stimulation by differentiation medium. Furthermore, RNA interference-mediated knockdown of Hey1 downregulated the expression levels of DSPP in OLCs stimulated by differentiation medium. Taken together, the findings indicate that Hey1 may be a positive regulator of odontoblastic differentiation. The present study broadens the understanding of odontoblast differentiation and biomineralization.

High Bone Turnover in Mice Carrying a Pathogenic Notch2 Mutation Causing Hajdu-Cheney Syndrome.

Hajdu-Cheney syndrome (HCS) is a rare autosomal-dominant disorder primarily characterized by acro-osteolysis and early-onset osteoporosis. Genetically, HCS is caused by nonsense or deletion mutations within exon 34 of the NOTCH2 gene, resulting in premature translational termination and production of C-terminally truncated NOTCH2 proteins that are predicted to activate NOTCH2-dependent signaling. To understand the role of Notch2 in bone remodeling, we developed a mouse model of HCS by introducing a pathogenic mutation (6272delT) into the murine Notch2 gene. By μCT and undecalcified histology, we observed generalized osteopenia in two independent mouse lines derived by injection of different targeted embryonic stem (ES) cell clones, yet acro-osteolysis did not occur until the age of 52 weeks. Cellular and dynamic histomorphometry revealed a high bone turnover situation in Notch2+/HCS mice, since osteoblast and osteoclast indices were significantly increased compared with wild-type littermates. Whereas ex vivo cultures failed to uncover cell-autonomous gain-of-functions within the osteoclast or osteoblast lineage, an unbiased RNA sequencing approach identified Tnfsf11 and Il6 as Notch-signaling target genes in bone marrow cells cultured under osteogenic conditions. Because we further observed that the high-turnover pathology of Notch2+/HCS mice was fully normalized by alendronate treatment, our results demonstrate that mutational activation of Notch2 does not directly control osteoblast activity but favors a pro-osteoclastic gene expression pattern, which in turn triggers high bone turnover. © 2017 American Society for Bone and Mineral Research.

Dual Mechanism of Action of Resveratrol in Notch Signaling Pathway Activation in Osteosarcoma

Purpose: To demonstrate the effect of resveratrol on Notch signaling in MG-63 and U2OS osteosarcoma cell lines. Methods: Cell Counting Kit 8 reagent was used to analyze cell proliferation while TRIzol® reagent was employed for the extraction of total RNA. High Capacity cDNA reverse transcription chain reaction kit was used to transcribe 2 μg RNA. Western blot analysis was performed to examine Hes1 and Hey1 expression. Results: The results revealed that resveratrol treatment exhibited dual mechanisms of action on the activation of Notch signaling in osteosarcoma cells. The osteosarcoma cell lines, MG-63 and U2OS, when exposed to 20 μM concentration of resveratrol for 48 h showed significant toxicity compared to untreated cells. However, 30 μM concentration of resveratrol induced higher toxicity which was lethal to cell growth. The results from RT qPCR and Western blot data revealed a concentration-dependent effect of resveratrol on the expression of Notch signaling genes including Hes1, Hes5, Hey1, Hey2 and HeyL in U2OS cells. Treatment of U2OS cells with 20 μM concentration of resveratrol for 48 h induced a marked increase in the expression of Hes1, Hes5, Hey1, Hey2 and HeyL mRNA compared to the untreated cells. However, at a concentration of 30 μM, resveratrol inhibited the activation of Notch signaling pathway. This was evident by a decrease in the expression of Hes1, Hes5, Hey1, Hey2 and HeyL, Notch signaling target genes. Conclusion: Resveratrol plays an important role in the activation of Notch signaling pathway and may be of therapeutic benefit in the treatment of osteosarcoma. Keywords: Osteosarcoma, Dual action mechanism, Notch signaling pathway, Toxicity, Cell growth inhibition

The Anti-Adipogenic Potential of COUP-TFII Is Mediated by Downregulation of the Notch Target Gene Hey1.

BackgroundChicken ovalbumin upstream promoter transcription factor II (COUP-TFII) belongs to the steroid/thyroid hormone receptor superfamily and may contribute to the pathogenesis of obesity. It has not conclusively been established, however, whether its role is pro- or anti-adipogenic.Methods and ResultsGene silencing of Coup-tfII in 3T3-F442A preadipocytes resulted in enhanced differentiation into mature adipocytes. This was associated with upregulation of the Notch signaling target gene Hey1. A functional role of Hey1 was confirmed by gene silencing in 3T3-F442A preadipocytes, resulting in impaired differentiation. In vivo, de novo fat pad formation in NUDE mice was significantly stimulated following injection of preadipocytes with Coup-tfII gene silencing, but impaired with Hey1 gene silencing. Moreover, expression of Coup-tfII was lower and that of Hey1 higher in isolated adipocytes of obese as compared to lean adipose tissue.ConclusionsThese in vitro and in vivo data support an anti-adipogenic role of COUP-TFII via downregulating the Notch signaling target gene Hey1.

The vascular delta-like ligand-4 (DLL4)-Notch4 signaling correlates with angiogenesis in primary glioblastoma: an immunohistochemical study.

Delta-like ligand-4 (DLL4)-Notch signaling is known to play a pivotal role in the regulation of tumor angiogenesis. We had previously found that DLL4 was overexpressed, while Notch1 receptor, which binds to DLL4 during angiogenesis, was absent in the majority of human primary glioblastomas. Thus, DLL4-Notch signaling pathway in the regulation of tumor angiogenesis in primary glioblastoma remains unknown. Tumor tissues from 70 patients with primary glioblastoma were analyzed by immunohistochemistry for expression of components of DLL4-Notch signaling, vascular endothelial growth factor (VEGF), and microvessel density (MVD). Immunohistochemistry results showed that the positive staining of DLL4 and Notch4 was primarily distributed in tumor vascular endothelial cells but rarely detected in tumor cells. However, VEGF, hairy/enhancer of split-1 (HES1; a target gene of Notch signaling), and Notch1-3 expression was seen in both tumor vascular endothelial cells and tumor cells. Univariate analysis showed that the expression levels of VEGF and DLL4, HES1, and Notch4 in tumor endothelial cells were significantly associated with MVD in primary glioblastoma (P < 0.001). Binary logistic regression analysis showed that high expression levels of DLL4, HES1, and Notch4 in tumor endothelial cells were associated with a decrease of MVD in primary glioblastoma, while MVD increased with elevated VEGF expression in contrast. In addition, DLL4, Notch4, and HES1 expression were positively correlated in tumor vascular endothelial cells (P < 0.05). We conclude that the vascular DLL4-Notch4 signaling and VEGF signaling complementing each other plays an important role in the progression of tumor angiogenesis in primary glioblastoma. Graphical abstract A, positive staining of DLL4 in human kidney; B, positive staining of VEGF in human breast cancer; C, positive staining of CD34 in human lung cancer; D, positive staining of HES1 in human breast cancer; E-H, positive staining of Notch1-4: E-F in human lung cancer; G-H in human kidney.

Meta-analysis reveals the correlation of Notch signaling with non-small cell lung cancer progression and prognosis.

Various studies have assessed the clinicopathological and prognostic value of Notch1 and Notch3 expression in Non-small cell lung cancer (NSCLC), but their results remain controversial. This meta-analysis was conducted to address the above issues by using a total of 19 studies involving 3663 patients. The correlations between Notch1 and Notch3 expression and clinicopathological features and NSCLC prognosis were analyzed. The meta-analysis indicated that higher expression of Notch1 was associated with greater possibility of lymph node metastasis and higher TNM stages. Moreover, patients with Notch1 overexpression and Notch3 overexpression showed significantly poor overall survival (Notch1: HR, 1.29; 95% CI, 1.06–1.57, p = 0.468 and I2 = 0.0%; Notch3: HR, 1.57; 95%CI, 1.04-2.36, p = 0.445 and I2 = 0.0%). Furthermore, there are statistically significant association between overall survival of NSCLC patients and the expression of Notch signaling ligand DLL3 and target gene HES1. Our meta-analysis supports that Notch signaling is a valuable bio-marker to predict progression and targeting Notch signaling could benefit subpopulation of NSCLC patients.

Serum induces transcription of Hey1 and Hey2 genes by Alk1 but not Notch signaling in endothelial cells.

The transcriptional repressors Hey1 and Hey2 are primary target genes of Notch signaling in the cardiovascular system and induction of Hey gene expression is often interpreted as activation of Notch signaling. Here we report that treatment of primary human endothelial cells with serum or fresh growth medium led to a strong wave of Hey1 and Hey2 transcription lasting for approximately three hours. Transcription of other Notch target genes (Hes1, Hes5, ephrinB2, Dll4) was however not induced by serum in endothelial cells. Gamma secretase inhibition or expression of dominant-negative MAML1 did not prevent the induction of Hey genes indicating that canonical Notch signaling is dispensable. Pretreatment with soluble BMP receptor Alk1, but not Alk3, abolished Hey gene induction by serum. Consequently, the Alk1 ligand BMP9 stimulated Hey gene induction in endothelial cells. Several other cell types however did not show such a strong BMP signaling and consequently only a very mild induction of Hey genes. Taken together, the experiments revealed that bone morphogenic proteins within the serum of cell culture medium are potent inducers of endothelial Hey1 and Hey2 gene expression within the first few hours after medium change.

Osteocytes mediate the anabolic actions of canonical Wnt/β-catenin signaling in bone

Osteocytes, >90% of the cells in bone, lie embedded within the mineralized matrix and coordinate osteoclast and osteoblast activity on bone surfaces by mechanisms still unclear. Bone anabolic stimuli activate Wnt signaling, and human mutations of components along this pathway underscore its crucial role in bone accrual and maintenance. However, the cell responsible for orchestrating Wnt anabolic actions has remained elusive. We show herein that activation of canonical Wnt signaling exclusively in osteocytes [dominant active (da)βcat(Ot) mice] induces bone anabolism and triggers Notch signaling without affecting survival. These features contrast with those of mice expressing the same daß-catenin in osteoblasts, which exhibit decreased resorption and perinatal death from leukemia. daßcat(Ot) mice exhibit increased bone mineral density in the axial and appendicular skeleton, and marked increase in bone volume in cancellous/trabecular and cortical compartments compared with littermate controls. daßcat(Ot) mice display increased resorption and formation markers, high number of osteoclasts and osteoblasts in cancellous and cortical bone, increased bone matrix production, and markedly elevated periosteal bone formation rate. Wnt and Notch signaling target genes, osteoblast and osteocyte markers, and proosteoclastogenic and antiosteoclastogenic cytokines are elevated in bones of daßcat(Ot) mice. Further, the increase in RANKL depends on Sost/sclerostin. Thus, activation of osteocytic β-catenin signaling increases both osteoclasts and osteoblasts, leading to bone gain, and is sufficient to activate the Notch pathway. These findings demonstrate disparate outcomes of β-catenin activation in osteocytes versus osteoblasts and identify osteocytes as central target cells of the anabolic actions of canonical Wnt/β-catenin signaling in bone.