Notch signaling in human development and disease

Alagille Syndrome

Alagille syndrome is a complex multisystem autosomal dominant disorder with a wide variability in penetrance of clinical features. A majority of patients have pathogenic mutations in either the JAG1 gene, encoding a Notch pathway ligand, or the receptor NOTCH2. No genotype-phenotype correlations have been found in any organ system. Liver disease is a major cause of morbidity in this population, whereas cardiac and vascular involvement accounts for most of the mortality. Current therapies are supportive, but the future is promising for the development of targeted interventions to augment Notch pathway signaling in involved tissues.

Sensitized genetic backgrounds reveal differential roles for EGF repeat xylosyltransferases in Drosophila Notch signaling

In multicellular organisms, glycosylation regulates various developmental signaling pathways including the Notch pathway. One of the O-linked glycans added to epidermal growth factor-like (EGF) repeats in animal proteins including the Notch receptors is the xylose-xylose-glucose-O oligosaccharide. Drosophila glucoside xylosyltransferase (Gxylt) Shams negatively regulates Notch signaling in specific contexts. Since Shams adds the first xylose residue to O-glucose, its loss-of-function phenotype could be due to the loss of the first xylose, the second xylose or both. To examine the contribution of the second xylose residues to Drosophila Notch signaling, we have performed biochemical and genetic analysis on CG11388, which is the Drosophila homolog of human xyloside xylosyltransferase 1 (XXYLT1). Experiments in S2 cells indicated that similar to human XXYLT1, CG11388 can add the second xylose to xylose-glucose-O glycans. Flies lacking both copies of CG11388 (Xxylt) are viable and fertile and do not show gross phenotypes indicative of altered Notch signaling. However, genetic interaction experiments show that in sensitized genetic backgrounds with decreased or increased Notch pathway components, loss of Xxylt promotes Delta-mediated activation of Notch. Unexpectedly, we find that in such sensitized backgrounds, even loss of one copy of the fly Gxylt shams enhances Delta-mediated Notch activation. Taken together, these data indicate that while the first xylose plays a key role in tuning the Delta-mediated Notch signaling in Drosophila, the second xylose has a fine-tuning role only revealed in sensitized genetic backgrounds.

Fibrogenic Secretome of Sirtuin 1-Deficient Endothelial Cells: Wnt, Notch and Glycocalyx Rheostat

Sirtuins (SIRT) are ubiquitous histone and protein deacetylases and a member of this family, SIRT1, is the best-studied one. Its functions in endothelial cells encompass branching angiogenesis, activation of endothelial nitric oxide synthase, regulation of proapoptotic and proinflammatory pathways, among others. Defective SIRT1 activity has been described in various cardiovascular, renal diseases and in aging-associated conditions. Therefore, understanding of SIRT1-deficient, endothelial dysfunctional phenotype has much to offer clinically. Here, we summarize recent studies by several investigative teams of the characteristics of models of global endothelial SIRT1 deficiency, the causes of facilitative development of fibrosis in these conditions, dissect the protein composition of the aberrant secretome of SIRT1-deficient endothelial cells and present several components of this aberrant secretome that are involved in fibrogenesis via activation of fibroblasts to myofibroblasts. These include ligands of Wnt and Notch pathways, as well as proteolytic fragments of glycocalyx core protein, syndecan-4. The latter finding is crucial for understanding the degradation of glycocalyx that accompanies SIRT1 deficiency. This spectrum of abnormalities associated with SIRT1 deficiency in endothelial cells is essential for understanding the origins and features of endothelial dysfunction in a host of cardiovascular and renal diseases.

NOTCH3 expression is linked to breast cancer seeding and distant metastasis

Background

Development of distant metastases involves a complex multistep biological process termed the invasion-metastasis cascade, which includes dissemination of cancer cells from the primary tumor to secondary organs. NOTCH developmental signaling plays a critical role in promoting epithelial-to-mesenchymal transition, tumor stemness, and metastasis. Although all four NOTCH receptors show oncogenic properties, the unique role of each of these receptors in the sequential stepwise events that typify the invasion-metastasis cascade remains elusive.

Methods

We have established metastatic xenografts expressing high endogenous levels of NOTCH3 using estrogen receptor alpha-positive (ERα⁺) MCF-7 breast cancer cells with constitutive active Raf-1/mitogen-associated protein kinase (MAPK) signaling (vMCF-7^Raf-1) and MDA-MB-231 triple-negative breast cancer (TNBC) cells. The critical role of NOTCH3 in inducing an invasive phenotype and poor outcome was corroborated in unique TNBC cells resulting from a patient-derived brain metastasis (TNBC-M25) and in publicly available claudin-low breast tumor specimens collected from participants in the Molecular Taxonomy of Breast Cancer International Consortium database.

Results

In this study, we identified an association between NOTCH3 expression and development of metastases in ERα⁺ and TNBC models. ERα⁺ breast tumor xenografts with a constitutive active Raf-1/MAPK signaling developed spontaneous lung metastases through the clonal expansion of cancer cells expressing a NOTCH3 reprogramming network. Abrogation of NOTCH3 expression significantly reduced the self-renewal and invasive capacity of ex vivo breast cancer cells, restoring a luminal CD44^low/CD24^high/ERα^high phenotype. Forced expression of the mitotic Aurora kinase A (AURKA), which promotes breast cancer metastases, failed to restore the invasive capacity of NOTCH3-null cells, demonstrating that NOTCH3 expression is required for an invasive phenotype. Likewise, pharmacologic inhibition of NOTCH signaling also impaired TNBC cell seeding and metastatic growth. Significantly, the role of aberrant NOTCH3 expression in promoting tumor self-renewal, invasiveness, and poor outcome was corroborated in unique TNBC cells from a patient-derived brain metastasis and in publicly available claudin-low breast tumor specimens.

Conclusions

These findings demonstrate the key role of NOTCH3 oncogenic signaling in the genesis of breast cancer metastasis and provide a compelling preclinical rationale for the design of novel therapeutic strategies that will selectively target NOTCH3 to halt metastatic seeding and to improve the clinical outcomes of patients with breast cancer.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-1020-0) contains supplementary material, which is available to authorized users.

Two novel protein O-glucosyltransferases that modify sites distinct from POGLUT1 and affect Notch trafficking and signaling

The Notch-signaling pathway is normally activated by Notch-ligand interactions. A recent structural analysis suggested that a novel O-linked hexose modification on serine 435 of the mammalian NOTCH1 core ligand-binding domain lies at the interface with its ligands. This serine occurs between conserved cysteines 3 and 4 of Epidermal Growth Factor-like (EGF) repeat 11 of NOTCH1, a site distinct from those modified by protein O-glucosyltransferase 1 (POGLUT1), suggesting that a different enzyme is responsible. Here, we identify two novel protein O-glucosyltransferases, POGLUT2 and POGLUT3 (formerly KDELC1 and KDELC2, respectively), which transfer O-glucose (O-Glc) from UDP-Glc to serine 435. Mass spectrometric analysis of NOTCH1 produced in HEK293T cells lacking POGLUT2, POGLUT3, or both genes showed that either POGLUT2 or POGLUT3 can add this novel O-Glc modification. EGF11 of NOTCH2 does not have a serine residue in the same location for this O-glucosylation, but EGF10 of NOTCH3 (homologous to EGF11 in NOTCH1 and -2) is also modified at the same position. Comparison of the sites suggests a consensus sequence for modification. In vitro assays with POGLUT2 and POGLUT3 showed that both enzymes modified only properly folded EGF repeats and displayed distinct acceptor specificities toward NOTCH1 EGF11 and NOTCH3 EGF10. Mutation of the O-Glc modification site on EGF11 (serine 435) in combination with sensitizing O-fucose mutations in EGF8 or EGF12 affected cell-surface presentation of NOTCH1 or reduced activation of NOTCH1 by Delta-like1, respectively. This study identifies a previously undescribed mechanism for fine-tuning the Notch-signaling pathway in mammals.

Wee1 kinase inhibitor MK-1775 induces apoptosis of acute lymphoblastic leukemia cells and enhances the efficacy of doxorubicin involving downregulation of Notch pathway

Acute lymphoblastic leukemia (ALL) is an aggressive hematologic malignancy affecting pediatric and adult populations. Although the outcomes of ALL in children have improved markedly in previous years, limited treatment strategies are available at present for adult patients with ALL. Wee1 is a crucial cell cycle checkpoint kinase of G2/M that regulates cell cycle progression and maintains chromatin integrity. MK-1775, a selective inhibitor of Wee1 has recently been identified to be able to induce apoptosis of tumor cells by abrogating G2/M checkpoint. The present study investigated the anti-leukemic activity of MK-1775 alone and in combination with doxorubicin (Adriamycin^®; ADM) in various human ALL cell lines. MK-1775 treatment induced apoptosis of ALL cells, accompanied by unscheduled mitotic entry and downregulation of Notch pathway. The anti-leukemic activity of MK-1775 was in a concentration- and time-dependent manner. The data also indicated that it decreased the half-maximal inhibitory concentration (IC₅₀) of ADM compared with the control group. The combination of MK-1775 and ADM induced an increased apoptotic rate compared with each agent alone. In addition, the human bone marrow stromal cell HS-5 cell line was detected to exhibit an increased IC₅₀ value of MK-1775 treatment in contrast to ALL cell lines. It indicates that the hematopoietic supportive capability may remain intact during the treatment of MK-1775. Taken together, the Wee1 inhibitor MK-1775 may be an attractive agent in the treatment of patients with ALL.

Dll1 Marks Cells of Origin of Ras-Induced Cancer in Mouse Squamous Epithelia

The Notch signaling pathway has been implicated in homeostasis and disease, including cancer, in various tissues. Moreover, it has been involved both in stem cell maintenance and differentiation, in a context-dependent manner. Stem/progenitor cells, on the other hand, have long been suspected to be the cells of origin in various malignancies. In order to gain insight in the role of the Notch ligand Dll1 in mouse development, we generated a knock-in line expressing an inducible Cre recombinase. We have employed in vivo approaches in mice to genetically mark rare subpopulations of cells expressing Dll1 in various adult tissues. Moreover, we conditionally expressed a constitutively active Ras oncoprotein in these cells and showed that within days, mice develop squamous neoplasias in the skin, as well as in the stomach.

RBPJ polymorphisms associated with cerebral infarction diseases in Chinese Han population: A Clinical Trial/Experimental Study (CONSORT Compliant)

TRIAL DESIGN

Cerebral small vessel diseases (CSVDs) are a group of brain pathological processes involving cerebral small arteries, brain venules, and capillaries. The recombination signal-binding protein Jκ (RBPJ) is implicated in the pathogenesis of these diseases but its actual roles need confirmation. The aim of this work was to evaluate variations in RBPJ gene for their possible associations with the disease.

METHODS

The RBPJ gene was sequenced for 400 patients with cerebral infarction disease and 600 normal controls. The statistical analyses and Hardy-Weinberg equilibrium tests of the patients and control populations were conducted using the SPSS software (version 19.0) and Plink (version 1.9), Haploview software, and online software SNPSpD.

RESULTS

We characterized variants rs2871198, rs1397731, rs3822223, rs2077777, rs2270226, and rs2788861 within or near the RBPJ gene. The genetic heterozygosity of rs2871198, rs1397731, rs3822223, rs2077777, and rs2270226 was very high. Statistical analysis showed that the variants rs2270226 and rs2077777 in the gene were associated with the risk of cerebral infarction diseases in the Chinese Han population.

CONCLUSIONS

rs2270226 and rs2077777 in the RBPJ gene were associated with the risk of cerebral infarction diseases in the Chinese Han population.

JAG1 loss‑of‑function mutations contributed to Alagille syndrome in two Chinese families

Alagille syndrome (ALGS) is primarily caused by jagged1 (JAG1) mutations, 70% of which are protein‑truncating mutations. However, no mutation hotspots have been discovered, and the pathogenic mechanism is not fully understood. The aim of the present study was to analyze two protein‑truncating JAG1 mutations detected in three Chinese ALGS patients. Mutation c.1261delT (p.Cys421Valfs) was identified in one patient with hepatic damage, xanthomas, facial abnormalities and cardiovascular defects, which was inherited from his father. The other mutation, c.1382_1383delAC (p.Asp461Glyfs), carried by a pair of monozygotic twins with hepatic damage, facial abnormalities and cardiovascular defects, was de novo. Biological experiments were performed to study the characteristics and function of these mutations. The p.Cys421Valfs and p.Asp461Glyfs mutant proteins appeared to be truncated in western blotting using anti‑Flag bound to the N‑terminus of JAG1. The RBP‑Jκ‑responsive reporter gene assay was used to investigate the ability of mutant JAG1 proteins to activate the Notch signaling pathway. The mutant proteins had a lower luciferase activity than the wild‑type, indicating impaired transcriptional activation ability. Western blotting using soluble JAG1 from the culture medium revealed that the expression levels of the mutant proteins were lower than that of the wild‑type, suggesting that less mutant JAG1 protein underwent proteolytic cleavage than the wild‑type. In conclusion, these two loss‑of‑function JAG1 mutations may be associated with ALGS manifestations in these patients.

Dental implications in Hajdu-Cheney syndrome: A novel case report and review of the literature

OBJECTIVE

To identify the molecular genetic etiology of an individual with a dysmorphic face, unusual teeth mobility, and root resorption.

SUBJECTS AND METHODS

DNA samples were collected from a trio of family members, and whole-exome sequencing was performed.

RESULTS

Mutational analysis revealed a de novo mutation (c.6787C>T) in the last exon of the NOTCH2 gene. This mutation would introduce a premature stop codon [p.(Gln2263*)] and generate a truncated protein without C-terminus, escaping from the nonsense-mediated decay system. Sanger sequencing confirmed that this mutation was generated spontaneously.

CONCLUSIONS

In this study, we identified a novel nonsense mutation in the last exon of the NOTCH2 gene causing Hajdu-Cheney syndrome. We described the genotype and phenotype correlation and the related dental complications. These results will advance the understanding of the NOTCH2 signaling in periodontitis and root resorption.

Sequencing of Linkage Region on Chromosome 12p11 Identifies PKP2 as a Candidate Gene for Left Ventricular Mass in Dominican Families

Increased left ventricular mass (LVM) is an intermediate phenotype for cardiovascular disease (CVD) and a predictor of stroke. Using families from the Dominican Republic, we have previously shown LVM to be heritable and found evidence for linkage to chromosome 12p11. Our current study aimed to further characterize the QTL by sequencing the 1 LOD unit down region in 10 families from the Dominican Republic with evidence for linkage to LVM. Within this region, we tested 5477 common variants [CVs; minor allele frequency (MAF) ≥5%] using the Quantitative Transmission-Disequilibrium Test (QTDT). Gene-based analyses were performed to test rare variants (RVs; MAF < 5%) in 181 genes using the family-based sequence kernel association test. A sample of 618 unrelated Dominicans from the Northern Manhattan Study (NOMAS) and 12 Dominican families with Exome Array data were used for replication analyses. The most strongly associated CV with evidence for replication was rs1046116 (Discovery families P = 9.0 × 10-4; NOMAS P = 0.03; replication families P = 0.46), a missense variant in PKP2 In nonsynonymous RV analyses, PKP2 was one of the most strongly associated genes (P = 0.05) with suggestive evidence for replication in NOMAS (P = 0.05). PKP2 encodes the plakophilin 2 protein and is a desmosomal gene implicated in arrythmogenic right ventricular cardiomyopathy and recently in arrhythmogenic left ventricular cardiomyopathy, which makes PKP2 an excellent candidate gene for LVM. In conclusion, sequencing of our previously reported QTL identified common and rare variants within PKP2 to be associated with LVM. Future studies are necessary to elucidate the role these variants play in influencing LVM.

Identification of diverse target RNAs that are functionally regulated by human Pumilio proteins

Human Pumilio proteins, PUM1 and PUM2, are sequence specific RNA-binding proteins that regulate protein expression. We used RNA-seq, rigorous statistical testing and an experimentally derived fold change cut-off to identify nearly 1000 target RNAs-including mRNAs and non-coding RNAs-that are functionally regulated by PUMs. Bioinformatic analysis defined a PUM Response Element (PRE) that was significantly enriched in transcripts that increased in abundance and matches the PUM RNA-binding consensus. We created a computational model that incorporates PRE position and frequency within an RNA relative to the magnitude of regulation. The model reveals significant correlation of PUM regulation with PREs in 3' untranslated regions (UTRs), coding sequences and non-coding RNAs, but not 5' UTRs. To define direct, high confidence PUM targets, we cross-referenced PUM-regulated RNAs with all PRE-containing RNAs and experimentally defined PUM-bound RNAs. The results define nearly 300 direct targets that include both PUM-repressed and, surprisingly, PUM-activated target RNAs. Annotation enrichment analysis reveal that PUMs regulate genes from multiple signaling pathways and developmental and neurological processes. Moreover, PUM target mRNAs impinge on human disease genes linked to cancer, neurological disorders and cardiovascular disease. These discoveries pave the way for determining how the PUM-dependent regulatory network impacts biological functions and disease states.

A novel Notch1 missense mutation (C1133Y) in the Abruptex domain exhibits enhanced proliferation and invasion in oral squamous cell carcinoma

Background

Notch1 has been regarded as a fundamental regulator in tissue differentiation and stem cell properties. Recently, Notch1 mutations have been reported intensively both in solid tumors and in hematopoietic malignancies. However, little is known about the biological effect and the clinical implication of these reported mutations. Previously, we discovered several missense mutations in the Notch1 receptor in a Chinese population with oral squamous cell carcinoma (OSCC).

Methods

We selected a ‘hotspot’ mutation in the Abruptex domain (C1133Y). The expression of Notch1 was determined by western blot and real-time qPCR in OSCC cell lines transfected with pcDNA3.1-Notch1^WT, pcDNA3.1-Notch1^C1133Y, or pcDNA3.1 empty vector. CCK-8 assays were used to assess cell proliferation. Flow cytometry and western blot were used to confirm the alteration of cell cycle after transfection. Transwell assays and the detection of Epithelial-to-mesenchymal transition (EMT) markers were used to determine the invasive ability. The effects of Notch1 C1133Y mutation were analyzed by Immunofluorescence staining and the expression of EGFR-PI3K/AKT signaling.

Results

We demonstrated that Notch1^C1133Y mutation inactivated the canonical Notch1 signaling. We identified an oncogenic phenotype of this mutation by promoting cell proliferation, invasion and by inducing EMT in OSCC cell lines. We found that the Notch1^C1133Y mutation exhibited a decreased S1-cleavage due to the impaired transport of Notch1 protein from the endoplasmic reticulum (ER) to the Golgi complex, which was consistent with the observation of the failure of the Notch1^C1133Y mutated receptor to present at the cell surface. Importantly, the mutated Notch1 activated the EGFR-PI3K/AKT signaling pathway, which has been confirmed as an overwhelming modulator in OSCC.

Conclusions

Taken together, our findings revealed for the first time a novel Notch1 mutation that enhances proliferation and invasion in OSCC cell lines. The Notch1 C1133Y mutation impairs the processing of notch1 protein and the critical links between the mutated Notch1 and the activated EGFR-PI3K/AKT signaling pathway.

Electronic supplementary material

The online version of this article (10.1186/s12935-017-0496-5) contains supplementary material, which is available to authorized users.

Structural Insights into Notch Receptor-Ligand Interactions

Pioneering cell aggregation experiments from the Artavanis-Tsakonas group in the late 1980's localized the core ligand recognition sequence in the Drosophila Notch receptor to epidermal growth factor-like (EGF) domains 11 and 12. Since then, advances in protein expression, structure determination methods and functional assays have enabled us to define the molecular basis of the core receptor/ligand interaction and given new insights into the architecture of the Notch complex at the cell surface. We now know that Notch EGF11 and 12 interact with the Delta/Serrate/LAG-2 (DSL) and C2 domains of ligand and that membrane-binding, together with additional protein-protein interactions outside the core recognition domains, are likely to fine-tune generation of the Notch signal. Furthermore, structure determination of O-glycosylated variants of Notch alone or in complex with receptor fragments, has shown that these sugars contribute directly to the binding interface, as well as to stabilizing intra-molecular domain structure, providing some mechanistic insights into the observed modulatory effects of O-glycosylation on Notch activity.Future challenges lie in determining the complete extracellular architecture of ligand and receptor in order to understand (i) how Notch/ligand complexes may form at the cell surface in response to physiological cues, (ii) the role of lipid binding in stabilizing the Notch/ligand complex, (iii) the impact of O-glycosylation on binding and signalling and (iv) to dissect the different pathologies that arise as a consequence of mutations that affect proteins involved in the Notch pathway.

Integration of Drosophila and Human Genetics to Understand Notch Signaling Related Diseases

Notch signaling research dates back to more than one hundred years, beginning with the identification of the Notch mutant in the fruit fly Drosophila melanogaster. Since then, research on Notch and related genes in flies has laid the foundation of what we now know as the Notch signaling pathway. In the 1990s, basic biological and biochemical studies of Notch signaling components in mammalian systems, as well as identification of rare mutations in Notch signaling pathway genes in human patients with rare Mendelian diseases or cancer, increased the significance of this pathway in human biology and medicine. In the 21st century, Drosophila and other genetic model organisms continue to play a leading role in understanding basic Notch biology. Furthermore, these model organisms can be used in a translational manner to study underlying mechanisms of Notch-related human diseases and to investigate the function of novel disease associated genes and variants. In this chapter, we first briefly review the major contributions of Drosophila to Notch signaling research, discussing the similarities and differences between the fly and human pathways. Next, we introduce several biological contexts in Drosophila in which Notch signaling has been extensively characterized. Finally, we discuss a number of genetic diseases caused by mutations in genes in the Notch signaling pathway in humans and we expand on how Drosophila can be used to study rare genetic variants associated with these and novel disorders. By combining modern genomics and state-of-the art technologies, Drosophila research is continuing to reveal exciting biology that sheds light onto mechanisms of disease.

Targeted Gene Knock Out Using Nuclease-Assisted Vector Integration: Hemi- and Homozygous Deletion of JAG1

Gene editing technologies are revolutionizing fields such as biomedicine and biotechnology by providing a simple means to manipulate the genetic makeup of essentially any organism. Gene editing tools function by introducing double-stranded breaks at targeted sites within the genome, which the host cells repair preferentially by Non-Homologous End Joining. While the technologies to introduce double-stranded breaks have been extensively optimized, this progress has not been matched by the development of methods to integrate heterologous DNA at the target sites or techniques to detect and isolate cells that harbor the desired modification. We present here a technique for rapid introduction of vectors at target sites in the genome that enables efficient isolation of successfully edited cells.

Leukemia-specific delivery of mutant NOTCH1 targeted therapy

NOTCH1 is an attractive cancer target, particularly in T cell acute lymphoblastic leukemia (T-ALL), with activating mutations in this gene identified in more than 50% of cases. In this study, Roti et al. describe the synthesis, characterization, and validation of JQ-FT, a first-in-class NOTCH1 inhibitor that has dual selectivity for leukemia over normal cells and NOTCH1 mutants over wild-type receptors.

On-target drug delivery remains a challenge in cancer precision medicine; it is difficult to deliver a targeted therapy to cancer cells without incurring toxicity to normal tissues. The SERCA (sarco-endoplasmic reticulum Ca²⁺ ATPase) inhibitor thapsigargin inhibits mutant NOTCH1 receptors compared with wild type in T cell acute lymphoblastic leukemia (T-ALL), but its administration is predicted to be toxic in humans. Leveraging the addiction of ALL to folic acid, we conjugated folate to an alcohol derivative of thapsigargin via a cleavable ester linkage. JQ-FT is recognized by folate receptors on the plasma membrane and delivered into leukemia cells as a potent antileukemic agent. In mechanistic and translational models of T-ALL, we demonstrate NOTCH1 inhibition in vitro and in vivo. These proof-of-concept studies support the further optimization of this first-in-class NOTCH1 inhibitor with dual selectivity: leukemia over normal cells and NOTCH1 mutants over wild-type receptors. Furthermore, tumor-specific disruption of Notch signaling may overcome legitimate concerns associated with the tumor suppressor function of nontargeted Notch pathway inhibitors.

The notch pathway is activated in neoplastic progression in esophageal squamous cell carcinoma

The Notch signaling pathway is integral to normal human development and homeostasis and has a deterministic function on cell differentiation. Recent studies suggest aberrant Notch signaling may contribute to neoplastic progression by an increase in stem cell survival, chemoresistance, and the promotion of epithelial-to-mesenchymal transition. The goals of our study were to determine, utilizing quantitative technologies, the expression of activated Notch 1 in esophageal squamous cell carcinoma (SCC) and to determine the relationship between Notch 1 expression and various clinicopathologic parameters. Immunohistochemical staining for Notch intracellular domain (NICD) was performed on 60 consecutive cases of esophageal squamous cell carcinoma, 42 cases of benign esophageal squamous epithelium, and 13 cases of eosinophilic esophagitis diagnosed in our department from 2007 through 2015, and exact nuclear staining and nuclear characteristics were graded using the Vectra imaging system. Clinicopathologic data (gender, age at diagnosis, smoking status, tumor grade, tumor stage, tumor location, and survival) were collected for each SCC case and these were correlated with NICD staining. Cases of esophageal SCC demonstrated significantly higher NICD staining compared to cases of benign and reactive esophageal epithelium (P=.003 and .005, respectively). Among cases of esophageal SCC, nuclear NICD staining was significantly correlated with both tumor grade and stage. Following classification and regression tree analysis, esophageal SCC patients with increased NICD expression were found to be more likely to die from their disease than those with lower levels of expression. Taken together, the findings suggest that increased Notch 1 may contribute to the development and aggressiveness of esophageal SCC.

The developmental biology of genetic Notch disorders

Notch signaling regulates a vast array of crucial developmental processes. It is therefore not surprising that mutations in genes encoding Notch receptors or ligands lead to a variety of congenital disorders in humans. For example, loss of function of Notch results in Adams-Oliver syndrome, Alagille syndrome, spondylocostal dysostosis and congenital heart disorders, while Notch gain of function results in Hajdu-Cheney syndrome, serpentine fibula polycystic kidney syndrome, infantile myofibromatosis and lateral meningocele syndrome. Furthermore, structure-abrogating mutations in NOTCH3 result in CADASIL. Here, we discuss these human congenital disorders in the context of known roles for Notch signaling during development. Drawing on recent analyses by the exome aggregation consortium (EXAC) and on recent studies of Notch signaling in model organisms, we further highlight additional Notch receptors or ligands that are likely to be involved in human genetic diseases.

Human hepatic organoids for the analysis of human genetic diseases

We developed an in vitro model system where induced pluripotent stem cells (iPSCs) differentiate into 3-dimensional human hepatic organoids (HOs) through stages that resemble human liver during its embryonic development. The HOs consist of hepatocytes, and cholangiocytes, which are organized into epithelia that surround the lumina of bile duct-like structures. The organoids provide a potentially new model for liver regenerative processes, and were used to characterize the effect of different JAG1 mutations that cause: (a) Alagille syndrome (ALGS), a genetic disorder where NOTCH signaling pathway mutations impair bile duct formation, which has substantial variability in its associated clinical features; and (b) Tetralogy of Fallot (TOF), which is the most common form of a complex congenital heart disease, and is associated with several different heritable disorders. Our results demonstrate how an iPSC-based organoid system can be used with genome editing technologies to characterize the pathogenetic effect of human genetic disease-causing mutations.

Structural and functional dissection of the interplay between lipid and Notch binding by human Notch ligands

Recent data have expanded our understanding of Notch signalling by identifying a C2 domain at the N-terminus of Notch ligands, which has both lipid- and receptor-binding properties. We present novel structures of human ligands Jagged2 and Delta-like4 and human Notch2, together with functional assays, which suggest that ligand-mediated coupling of membrane recognition and Notch binding is likely to be critical in establishing the optimal context for Notch signalling. Comparisons between the Jagged and Delta family show a huge diversity in the structures of the loops at the apex of the C2 domain implicated in membrane recognition and Jagged1 missense mutations, which affect these loops and are associated with extrahepatic biliary atresia, lead to a loss of membrane recognition, but do not alter Notch binding. Taken together, these data suggest that C2 domain binding to membranes is an important element in tuning ligand-dependent Notch signalling in different physiological contexts.

MiR-18a-5p inhibits endothelial-mesenchymal transition and cardiac fibrosis through the Notch2 pathway

Hyperglycemia plays a crucial role in the pathogenesis of diabetic complications; however, the mechanisms underlying diabetic cardiac fibrosis remain unclear. Endothelial cells are known to contribute to cardiac fibrosis through endothelial-mesenchymal transition (EndMT) under high glucose stimulation. Here we investigated the expression of miR-18a-5p and examined its functional role in human aortic valvular endothelial cells (HAVECs). Using HAVECs, we revealed that miR-18a-5p regulated high glucose-induced EndMT. Moreover, high glucose levels induced Notch2 expression, which promoted EndMT, resulting in the downregulation of vascular endothelial cadherin and CD31 and upregulation of fibroblast-specific protein-1, α-smooth muscle actin, fibronectin, and vimentin. Furthermore, Notch2 was identified as a target of miR-18a-5p. Our data showed that the overexpression of miR-18a-5p could downregulate Notch2 expression and subsequently suppress EndMT. In conclusion, our findings demonstrated that miR-18a-5p/Notch2 signaling pathway participates in the regulation of high glucose-induced EndMT, and may act as a novel promising target for myocardial fibrosis in diabetic cardiomyopathy.

Endothelial Hey2 deletion reduces endothelial-to-mesenchymal transition and mitigates radiation proctitis in mice

The current study evaluated the role of Hey2 transcription factor in radiation-induced endothelial-to-mesenchymal transition (EndoMT) and its impact on radiation-induced tissue damage in mice. Phenotypic modifications of irradiated, Hey2 siRNA- and Hey2 vector plasmid-transfected human umbilical vein endothelial cells (HUVECs) resembling EndoMT were monitored by qPCR, immunocytochemistry and western blots. Subsequently, in mice, a Cre-LoxP strategy for inactivation of Hey2 specifically in the endothelium was used to study the biological consequences. Total body irradiation and radiation proctitis were monitored to investigate the impact of conditional Hey2 deletion on intestinal stem cells and microvascular compartment radiosensitivity, EndoMT and rectal damage severity. We found that EndoMT occurs in irradiated HUVECs with concomitant Hey2 mRNA and protein increase. While Hey2 silencing has no effect on radiation-induced EndoMT in vitro, Hey2 overexpression is sufficient to induce phenotypic conversion of endothelial cells. In mice, the conditional deletion of Hey2 reduces EndoMT frequency and the severity of rectal tissue damage. Our data indicate that the reduction in mucosal damage occurs through decline in stem/clonogenic epithelial cell loss mediated by microvascular protection. EndoMT is involved in radiation proctitis and this study demonstrates that a strategy based on the reduction of EndoMT mitigates intestinal tissue damage.

Notch system is differentially expressed and activated in pituitary adenomas of distinct histotype, tumor cell lines and normal pituitaries

Pituitary adenomas are among the most frequent intracranial neoplasms and treatment depends on tumor subtype and clinical features. Unfortunately, non responder cases occur, then new molecular targets are needed.

Notch system component expression and activation data are scarce in pituitary tumorigenesis, we therefore aimed to characterize Notch system in pituitary tumors of different histotype. In human pituitary adenomas we showed NOTCH1-4 receptors, JAGGED1 ligand and HES1 target gene expression with positive correlations between NOTCH1,2,4 and HES1, and NOTCH3 and JAGGED1 denoting Notch system activation in a subset of tumors. Importantly, NOTCH3 positive cells were higher in corticotropinomas and somatotropinomas compared to non functioning adenomas. In accordance, Notch activation was evidenced in AtT20 tumor corticotropes, with higher levels of NOTCH1-3 active domains, Jagged1 and Hes1 compared to normal pituitary.

In the prolactinoma cell lines GH3 and MMQ, in vivo GH3 tumors and normal glands, Notch system activation was lower than in corticotropes. In MMQ cells only the NOTCH2 active domain was increased, whereas NOTCH1 active domain was higher in GH3 tumors. High levels of Jagged1 and Dll1 were found solely in GH3 cells, and Hes1, Hey1 and Hey2 were expressed in a model dependent pattern.

Prolactinomas harbored by lacDrd2KO mice expressed high levels of NOTCH1 active domain and reduced Hes1.

We show a differential expression of Notch system components in tumoral and normal pituitaries and specific Notch system involvement depending on adenoma histotype, with higher activation in corticotropinomas. These data suggest that targeting Notch pathway may benefit non responder pituitary adenomas.

Maternal intake of high n-6 polyunsaturated fatty acid diet during pregnancy causes transgenerational increase in mammary cancer risk in mice

BACKGROUND

Maternal and paternal high-fat (HF) diet intake before and/or during pregnancy increases mammary cancer risk in several preclinical models. We studied if maternal consumption of a HF diet that began at a time when the fetal primordial germ cells travel to the genital ridge and start differentiating into germ cells would result in a transgenerational inheritance of increased mammary cancer risk.

METHODS

Pregnant C57BL/6NTac mouse dams were fed either a control AIN93G or isocaloric HF diet composed of corn oil high in n-6 polyunsaturated fatty acids between gestational days 10 and 20. Offspring in subsequent F1-F3 generations were fed only the control diet.

RESULTS

Mammary tumor incidence induced by 7,12-dimethylbenz[a]anthracene was significantly higher in F1 (p < 0.016) and F3 generation offspring of HF diet-fed dams (p < 0.040) than in the control offspring. Further, tumor latency was significantly shorter (p < 0.028) and burden higher (p < 0.027) in F1 generation HF offspring, and similar trends were seen in F3 generation HF offspring. RNA sequencing was done on normal mammary glands to identify signaling differences that may predispose to increased breast cancer risk by maternal HF intake. Analysis revealed 1587 and 4423 differentially expressed genes between HF and control offspring in F1 and F3 generations, respectively, of which 48 genes were similarly altered in both generations. Quantitative real-time polymerase chain reaction analysis validated 13 chosen up- and downregulated genes in F3 HF offspring, but only downregulated genes in F1 HF offspring. Ingenuity Pathway Analysis identified upregulation of Notch signaling as a key alteration in HF offspring. Further, knowledge-fused differential dependency network analysis identified ten node genes that in the HF offspring were uniquely connected to genes linked to increased cancer risk (ANKEF1, IGFBP6, SEMA5B), increased resistance to cancer treatments (SLC26A3), poor prognosis (ID4, JAM3, TBX2), and impaired anticancer immunity (EGR3, ZBP1).

CONCLUSIONS

We conclude that maternal HF diet intake during pregnancy induces a transgenerational increase in offspring mammary cancer risk in mice. The mechanisms of inheritance in the F3 generation may be different from the F1 generation because significantly more changes were seen in the transcriptome.

NOVEL GENETIC FINDINGS IN A CHINESE FAMILY WITH EARLY-ONSET FEMALE-RELATED TYPE 2 DIABETES

No inheritance of early-onset female-related type 2 diabetes was reported within Chinese families. In this study, we aim to describe the inheritance pattern of type 2 diabetes in a 3-generation family and identify the gene responsible for type 2 diabetes. Genome-wide multipoint parametric linkage analysis revealed a maximum multipoint logarithm of odds (lod) score of 2.1 for a locus being associated with type 2 diabetes in this family on chromosome 20p11.2-12 between 23.5~30.8cM. Type 2 diabetes may be transmitted as an autosomal dominant trait with a high female-related penetrance in this family. Here we describe the first genetic locus for type 2 diabetes at chromosome 20p11.2-12. This region contains 8 known or predicted genes (PLCB1, PLCB4, LAMP5, PAK7, ANKEF1, SNAP25, SLX4IP, and JAG1). Gene SNAP25 which linked to energy or glucose homeostasis associated phenotypes may play a role in the development of type 2 diabetes in this family.

NICD inhibits cell proliferation and promotes apoptosis and autophagy in PC12 cells

Pheochromocytoma is a tumor of the adrenal medulla for which surgical resection is the only therapy. Though the Notch1 signaling pathway has been suggested as a target for pheochromocytoma treatment, the effect of Notch1 intracellular domain (NICD) on pheochromocytoma cell growth remains unknown. In the present study, the effect of NICD on pheochromocytoma cell growth was examined, by use of a tetracycline‑inducible system for NICD overexpression in the PC12 pheochromocytoma cell line. Flow cytometry was used to determine the effect of NICD on cell cycle phase distribution and apoptosis in PC12 cells. Protein expression levels of microtubule associated protein 1 light chain 3 B (LC3B), Beclin 1, autophagy‑related (ATG) 5 and ATG7 were examined using western blot analysis. Untreated PC12 cells lack NICD expression, while treatment with doxycycline resulted in a significant NICD overexpression. NICD overexpression promoted cell apoptosis and suppressed cell proliferation via regulating S‑phase arrest. In addition, NICD overexpression stimulated the expression of autophagy‑related proteins LC3B, Beclin 1, ATG5 and ATG7. In conclusion, NICD promoted cell apoptosis, suppressed cell proliferation, and stimulated autophagy‑related protein expression in PC12 cells. The present data indicate that overexpression of NICD may be a promising potential therapy for pheochromocytoma.

lncRNA H19 mediates BMP9-induced osteogenic differentiation of mesenchymal stem cells (MSCs) through Notch signaling

Mesenchymal stem cells (MSCs) are multipotent progenitor cells that can undergo self-renewal and differentiate into multiple lineages. Osteogenic differentiation from MSCs is a well-orchestrated process and regulated by multiple signaling pathways. We previously demonstrated that BMP9 is one of the most potent osteogenic factors. However, molecular mechanism through which BMP9 governs osteoblastic differentiation remains to be fully understood. Increasing evidence indicates noncoding RNAs (ncRNAs) may play important regulatory roles in many physiological and/or pathologic processes. In this study, we investigate the role of lncRNA H19 in BMP9-regulated osteogenic differentiation of MSCs. We demonstrated that H19 was sharply upregulated at the early stage of BMP9 stimulation of MSCs, followed by a rapid decease and gradual return to basal level. This process was correlated with BMP9-induced expression of osteogenic markers. Interestingly, either constitutive H19 expression or silencing H19 expression in MSCs significantly impaired BMP9-induced osteogenic differentiation in vitro and in vivo, which was effectively rescued by the activation of Notch signaling. Either constitutive H19 expression or silencing H19 expression led to the increased expression of a group of miRNAs that are predicted to target Notch ligands and receptors. Thus, these results indicate that lncRNA H19 functions as an important mediator of BMP9 signaling by modulating Notch signaling-targeting miRNAs. Our findings suggest that the well-coordinated biphasic expression of lncRNA H19 may be essential in BMP9-induced osteogenic differentiation of MSCs, and that dysregulated H19 expression may impair normal osteogenesis, leading to pathogenic processes, such as bone tumor development.

From the outside, from within: Biological and therapeutic relevance of signal transduction in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological cancer that arises from clonal expansion of transformed T-cell precursors. In this review we summarize the current knowledge on the external stimuli and cell-intrinsic lesions that drive aberrant activation of pivotal, pro-tumoral intracellular signaling pathways in T-cell precursors, driving transformation, leukemia expansion, spread or resistance to therapy. In addition to their pathophysiological relevance, receptors and kinases involved in signal transduction are often attractive candidates for targeted drug development. As such, we discuss also the potential of T-ALL signaling players as targets for therapeutic intervention.

COX-2 regulates Snail expression in gastric cancer via the Notch1 signaling pathway

The conversion of arachidonic acid into prostaglandins by cyclooxygenase (COX)-2 contributes to the biological properties of malignant tumours. During the initiation and development of various tumours, the Notch family plays a key role. However, the association between COX‑2 and the Notch family in gastric cancer (GC) remains unclear. The present study aimed to clarify the mechanisms through which COX‑2 participates in the pathogenesis of GC. Quantitative PCR and western blot analysis were used to detect the expression of Notch family members and COX‑2 in human GC and paracancerous tissues, GES‑1 cells and GC cell lines (AGS, SGC‑7901, BGC‑823, and MGC‑803) treated with or without celecoxib, prostaglandin E2 and small interfering RNA (siRNA). A CCK‑8 assay was performed to detect the proliferation of GC cells transfected with siRNA against COX‑2 (si‑COX‑2). A high mRNA expression of Notch1 and a decreased expression of Notch-1 intracellular active domain (N1IC) in GC were found to be related to the depth of invasion and TNM staging. The mRNA levels of Notch2, Notch3, Jagged1 and N2IC were found to be high in GC. A High expression of COX‑2 was associated with poorly differentiated and deeply invasive GC. COX‑2 and Notch1 exhibited an inverse expression pattern in the GES‑1 cells and different GC cell lines; the inhibition of COX‑2 increased Notch1 expression and activated the GC cells, whereas Notch1 downregulation had the opposite effect. Notch1 exhibited varying effects on Snail in the GC cell lines. The downregulation of COX‑2 expression significantly inhibited the proliferation of GC cells. On the whole, the expression of Notch signalling molecules differed in GC. COX‑2 inversely regulated Notch1 in GC and partially depended on the Notch1 signalling pathway in altering the expression of Snail.

Alagille syndrome: Genetics and Functional Models

Purpose of review

We review the genetics of the autosomal dominant, multi-system disorder, Alagille syndrome and provide a summary on how current functional models and emerging biotechnologies are equipped to guide scientists towards novel therapies. The importance of haploinsufficiency as a disease mechanism will be underscored throughout this discussion.

Recent findings

Alagille syndrome, a human disorder affecting the liver, heart, vasculature, kidney, and other systems, is caused by mutations in the Notch signaling pathway ligand, Jagged1 (JAG1) or the receptor, NOTCH2. Current advances in animal modeling, in vitro cell culture, and human induced pluripotent stem cells, provide new opportunities in which to study disease mechanisms and manifestations.

Summary

We anticipate that the availability of innovative functional models will allow scientists to test new gene therapies or small molecule treatments in physiologically-relevant systems. With these advances, we look forward to the development of new methods to help Alagille syndrome patients.

Using zebrafish to model liver diseases-Where do we stand?

Purpose of Review

The liver is the largest internal organ and performs both exocrine and endocrine function that is necessary for survival. Liver failure is among the leading causes of death and represents a major global health burden. Liver transplantation is the only effective treatment for end-stage liver diseases. Animal models advance our understanding of liver disease etiology and hold promise for the development of alternative therapies. Zebrafish has become an increasingly popular system for modeling liver diseases and complements the rodent models.

Recent Findings

The zebrafish liver contains main cell types that are found in mammalian liver and exhibits similar pathogenic responses to environmental insults and genetic mutations. Zebrafish have been used to model neonatal cholestasis, cholangiopathies, such as polycystic liver disease, alcoholic liver disease, and non-alcoholic fatty liver disease. It also provides a unique opportunity to study the plasticity of liver parenchymal cells during regeneration.

Summary

In this review, we summarize the recent work of building zebrafish models of liver diseases. We highlight how these studies have brought new knowledge of disease mechanisms. We also discuss the advantages and challenges of using zebrafish to model liver diseases.

Patient complexity and genotype-phenotype correlations in biliary atresia: a cross-sectional analysis

Background

Biliary Atresia (BA) is rare and genetically complex, and the pathogenesis is elusive. The disease course is variable and can represent heterogeneity, which hinders effective disease management. Deciphering the BA phenotypic variance is a priority in clinics and can be achieved by the integrative analysis of genotype and phenotype. We aim to explore the BA phenotypic features and to delineate the source of its variance.

Methods

The study is a cross-sectional observational study collating with case/control association analysis. One-hundred-and-eighty-one type III non-syndromic BA patients and 431 controls were included for case–control association tests, including 89 patients (47.19% males, born June 15th, 1981 to September 17th, 2007) have detailed clinical records with follow-up of the disease course (median ~17.2 years). BA-association genes from the genome-wide gene-based association test on common genetic variants (CV) and rare copy-number-variants (CNVs) from the genome-wide survey, the later comprise only CNVs > 100 kb and found in the BA patients but not in the local population (N = 1,381) or the database (N = 11,943). Hereby comorbidity is defined as a chronic disease that affects the BA patients but has no known relationship with BA or with the BA treatment. We examined genotype-phenotype correlations of CNVs, connectivity of these novel variants with BA-associated CVs, and their role in the BA candidate gene network.

Results

Of the 89 patients, 41.57% have comorbidities, including autoimmune-allergic disorders (22.47%). They carried 29 BA-private CNVs, including 3 CNVs underpinning the carriers’ immunity comorbidity and one JAG1 micro-deletion. The BA-CNV-intersected genes (N = 102) and the CV-tagged genes (N = 103) were both enriched with immune-inflammatory pathway genes (FDR q < 0.20), and the two gene sets were interconnected (permutation p = 0.039). The molecular network representing CVs and rare-CNV association genes fit into a core/periphery structure, the immune genes and their related modules are found at the coherence core of all connections, suggesting its dominant role in the BA pathogenesis pathway.

Conclusions

The study highlights a patient-complexity phenomenon as a novel BA phenotypic feature, which is underpinned by rare-CNVs that biologically converge with CVs into the immune-inflammatory pathway and drives the BA occurrence and the likely BA association with immune diseases in clinics.

Electronic supplementary material

The online version of this article (doi:10.1186/s12920-017-0259-0) contains supplementary material, which is available to authorized users.

The lysine deacetylase Sirtuin 1 modulates the localization and function of the Notch1 receptor in regulatory T cells

The ability to tune cellular functions in response to nutrient availability has important consequences for immune homeostasis. The activity of the receptor Notch in regulatory T (T_reg) cells, which suppress the functions of effector T cells, is indispensable for T_reg cell survival under conditions of diminished nutrient supply. Anti-apoptotic signaling induced by the Notch1 intracellular domain (NIC) originates from the cytoplasm and is spatially decoupled from the nuclear, largely transcriptional functions of NIC. We showed that Sirtuin 1 (Sirt1), which is an NAD⁺ (nicotinamide adenine dinucleotide)-dependent lysine deacetylase that inhibits NIC-dependent gene transcription, stabilized NIC proximal to the plasma membrane to promote the survival and function of activated T_reg cells. Sirt1 was required for NIC-dependent protection from apoptosis in cell lines but not for the activity of the anti-apoptotic protein Bcl-xL. In addition, a variant NIC protein in which four lysines were mutated to arginines (NIC4KR) retained anti-apoptotic activity, but was not regulated by Sirt1, and reconstituted the functions of nonnuclear NIC in Notch1-deficient T_reg cells. Loss of Sirt1 compromised T_reg cell survival, resulting in antigen-induced T cell proliferation and inflammation in two mouse models. Thus, the Sirt1-Notch interaction may constitute an important checkpoint that tunes noncanonical Notch1 signaling.

The role of Notch signaling in the mammalian ovary

The Notch pathway is a contact-dependent, or juxtacrine, signaling system that is conserved in metazoan organisms and is important in many developmental processes. Recent investigations have demonstrated that the Notch pathway is active in both the embryonic and postnatal ovary and plays important roles in events including follicle assembly and growth, meiotic maturation, ovarian vasculogenesis and steroid hormone production. In mice, disruption of the Notch pathway results in ovarian pathologies affecting meiotic spindle assembly, follicle histogenesis, granulosa cell proliferation and survival, corpora luteal function and ovarian neovascularization. These aberrations result in abnormal folliculogenesis and reduced fertility. The knowledge of the cellular interactions facilitated by the Notch pathway is an important area for continuing research, and future studies are expected to enhance our understanding of ovarian function and provide critical insights for improving reproductive health. This review focuses on the expression of Notch pathway components in the ovary, and on the multiple functions of Notch signaling in follicle assembly, maturation and development. We focus on the mouse, where genetic investigations are possible, and relate this information to the human ovary.

Notch signaling is important for epithelial-mesenchymal transition induced by low concentrations of doxorubicin in osteosarcoma cell lines

Osteosarcoma is an aggressive pediatric tumor affecting growing bones that typically occurs in adolescents and young adults. Although advances in treatment have been made in recent years, a high proportion of patients relapse due to metastases, which are frequently resistant to chemotherapy and pose a significant threat to long-term survival. Previous studies have demonstrated that the epithelial-mesenchymal transition (EMT) is associated with cancer occurrence and metastasis, and our previous study demonstrated the occurrence of EMT in osteosarcoma. Notch is a regulator involved in several cellular processes, and previous studies have identified that the Notch signaling pathway may be activated during chemotherapy. However, whether chemotherapy affects the EMT remains to be elucidated. To address this issue, in the present study osteosarcoma cells were exposed to sublethal doses of doxorubicin, which resulted in upregulation of the expression of genes in the Notch signaling pathway and its target genes. Furthermore, doxorubicin treatment promoted mesenchymal-like properties and enhanced the migration and invasion of cells. In addition, treatment with the selective γ-secretase inhibitor DAPT was able to prevent the EMT and inhibit the in vitro migration of osteosarcoma cells. The results of this study suggested that there is a significant correlation between the Notch signaling pathway and the EMT, and revealed an underlying molecular mechanism by which doxorubicin may induce the EMT via Notch signaling.

Zebrafish phenotypic screen identifies novel Notch antagonists

Zebrafish represents a powerful in vivo model for phenotype-based drug discovery to identify clinically relevant small molecules. By utilizing this model, we evaluated natural product derived compounds that could potentially modulate Notch signaling that is important in both zebrafish embryogenesis and pathogenic in human cancers. A total of 234 compounds were screened using zebrafish embryos and 3 were identified to be conferring phenotypic alterations similar to embryos treated with known Notch inhibitors. Subsequent secondary screens using HEK293T cells overexpressing truncated Notch1 (HEK293TΔE) identified 2 compounds, EDD3 and 3H4MB, to be potential Notch antagonists. Both compounds reduced protein expression of NOTCH1, Notch intracellular domain (NICD) and hairy and enhancer of split-1 (HES1) in HEK293TΔE and downregulated Notch target genes. Importantly, EDD3 treatment of human oral cancer cell lines demonstrated reduction of Notch target proteins and genes. EDD3 also inhibited proliferation and induced G₀/G₁ cell cycle arrest of ORL-150 cells through inducing p27^KIP1. Our data demonstrates the utility of the zebrafish phenotypic screen and identifying EDD3 as a promising Notch antagonist for further development as a novel therapeutic agent.

Research progress in the treatment of small cell lung cancer

Small cell lung cancer (SCLC) accounts for approximately 10-15% of all lung cancers. No significant improvement has been made for patients with SCLC in the past several decades. The main progresses were the thoracic radiation and prophylactic cranial irradiation (PCI) that improved the patient survival rate. For patients with limited disease and good performance status (PS), concurrent chemoradiotherapy (CCRT) followed by PCI should be considered. For extensive disease, the combination of etoposide and platinum-based chemotherapy remains the standard treatment and consolidative thoracic radiotherapy is beneficial for patients who have a significant respond to initial chemotherapy. However, the prognosis still remains poor. Recently, efforts have been focused on molecular targets and immunotherapy. But numerous molecular targets methods have failed to show a significant clinical benefit in patients with SCLC. It is anticipated that further development of research will depend on the on-going trials for molecular targeted therapy and immunotherapy which are promising and may improve the outcomes for SCLC in the next decade.

Clinical implications of APEX1 and Jagged1 as chemoresistance factors in biliary tract cancer

Purpose

Biliary cancer is a highly malignant neoplasm with poor prognosis and most patients need to undergo palliative chemotherapy, however major clinical problem associated with the use of chemotherapy is chemoresistance. So far, we aimed at investigating clinical implications of apurinic/apyrimidinic endodeoxyribonuclease 1 (APEX1) and Jagged1 as chemoresistance factors in biliary tract cancer.

Methods

We used 5 human biliary tract cancer cell lines (SNU-245, SNU-308, SNU-478, SNU-1079, and SNU-1196), and investigated the chemosensitivity of APEX1 and Jagged1 through 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and Western blot. Alternately, the 10 patients of advanced biliary cancer consist of 2 group according to the chemotherapy response examined by immunohistochemistry using APEX1 and Jagged1 antibody, and protein expression level was scored for staining intensity and percent positive cell.

Results

The result of MTT assay after APEX1 knockdown showed that strong coexpression of APEX1 and Jagged1 cell line (SNU-245, SNU-1079, and SNU-1196) showed a greater decrease in IC₅₀ of chemotherapeutic agent (5-fluorouracil, gemcitabine and cisplatin). The Western blot analysis of APEX1 and Jagged1 expression in biliary cancer cell lines after APEX1 knockdown definitively demonstrated decreased Jagged1 expression. The APEX1 and Jagged1expression level of immunohistochemistry represented that chemorefractory patients had higher than chemoresponsive patients.

Conclusion

These results demonstrate that simultaneous high expression of APEX1 and Jagged1 is associated with chemoresistance in biliary cancer and suggest that is a potential therapeutic target for chemoresistance in advanced biliary cancer.

Mammalian Polycistronic mRNAs and Disease

Our understanding of gene expression has come far since the 'one-gene one-polypeptide' hypothesis proposed by Beadle and Tatum. In this review, we address the gradual recognition that a growing number of polycistronic genes, originally discovered in viruses, are being identified within the mammalian genome, and that these may provide new insights into disease mechanisms and treatment. We carried out a systematic literature review identifying 13 mammalian genes for which there is evidence for polycistronic expression via translation through an internal ribosome entry site (IRES). Although the canonical mechanism of translation initiation has been studied extensively, here we highlight a process of noncanonical translation, IRES-mediated translation, that is a growing source for understanding complex inheritance, the elucidation of disease mechanisms, and the discovery of novel therapeutic targets. Identification of additional polycistronic genes may provide new insights into disease therapy and allow for new discoveries of both translational and disease mechanisms.

Jagged 1 is a major Notch ligand along cholangiocarcinoma development in mice and humans

Intrahepatic cholangiocarcinoma (ICC) is a rare yet deadly malignancy with limited treatment options. Activation of the Notch signalling cascade has been implicated in cholangiocarcinogenesis. However, while several studies focused on the Notch receptors required for ICC development, little is known about the upstream inducers responsible for their activation. Here, we show that the Jagged 1 (Jag1) ligand is almost ubiquitously upregulated in human ICC samples when compared with corresponding non-tumorous counterparts. Furthermore, we found that while overexpression of Jag1 alone does not lead to liver tumour development, overexpression of Jag1 synergizes with activated AKT signalling to promote liver carcinogenesis in AKT/Jag1 mice. Histologically, tumours consisted exclusively of ICC, with hepatocellular tumours not occurring in AKT/Jag1 mice. Furthermore, tumours from AKT/Jag1 mice exhibited extensive desmoplastic reaction, an important feature of human ICC. At the molecular level, we found that both AKT/mTOR and Notch cascades are activated in AKT/Jag1 ICC tissues, and that the Notch signalling is necessary for ICC development in AKT/Jag1 mice. In human ICC cell lines, silencing of Jag1 via specific small interfering RNA reduces proliferation and increases apoptosis. Finally, combined inhibition of AKT and Notch pathways is highly detrimental for the in vitro growth of ICC cell lines. In summary, our study demonstrates that Jag1 is an important upstream inducer of the Notch signalling in human and mouse ICC. Targeting Jag1 might represent a novel therapeutic strategy for the treatment of this deadly disease.

Family Based Whole Exome Sequencing Reveals the Multifaceted Role of Notch Signaling in Congenital Heart Disease

Left-ventricular outflow tract obstructions (LVOTO) encompass a wide spectrum of phenotypically heterogeneous heart malformations which frequently cluster in families. We performed family based whole-exome and targeted re-sequencing on 182 individuals from 51 families with multiple affected members. Central to our approach is the family unit which serves as a reference to identify causal genotype-phenotype correlations. Screening a multitude of 10 overlapping phenotypes revealed disease associated and co-segregating variants in 12 families. These rare or novel protein altering mutations cluster predominantly in genes (NOTCH1, ARHGAP31, MAML1, SMARCA4, JARID2, JAG1) along the Notch signaling cascade. This is in line with a significant enrichment (Wilcoxon, p< 0.05) of variants with a higher pathogenicity in the Notch signaling pathway in patients compared to controls. The significant enrichment of novel protein truncating and missense mutations in NOTCH1 highlights the allelic and phenotypic heterogeneity in our pediatric cohort. We identified novel co-segregating pathogenic mutations in NOTCH1 associated with left and right-sided cardiac malformations in three independent families with a total of 15 affected individuals. In summary, our results suggest that a small but highly pathogenic fraction of family specific mutations along the Notch cascade are a common cause of LVOTO.

Left-ventricular outflow tract obstructions comprise a group of developmental heart disorders that are genetically and phenotypically heterogeneous, with no single gene accounting for the majority of cases. In order to identify mutations contributing to disease, we selected patients from 51 families with a history of congenital cardiac malformations. We interrogated the entire coding sequences of 106 patients and identified a small but highly pathogenic fraction of mutations that are likely to contribute to disease in 12 families (23.5%). Furthermore, we present a strategy for identifying candidate mutations based on familial segregation in a genetically heterogeneous disorder.