Notch signaling plays an important role in developmental and pathological angiogenesis. Notch ligands, Dll4 and Jag1, have been implicated in tumor angiogenesis. Inhibition of Dll4-mediated Notch signaling results in hypersprouting of non-functional vasculature in tumors. We have constructed and analyzed pan-Notch ligand inhibitors, Notch1 decoys 1-24 and 1-36, which are based on the extracellular EGF-like repeats of Notch1. Both Notch1 decoys block angiogenesis in in vitro endothelial cell-based assays and in the mouse retina. We also show that they similarly inhibit Dll4- and Jag1-induced Notch signaling in vitro and result in a significant decrease in tumor growth and tumor vasculature in mouse and human tumor xenograft models. Interestingly, truncated Notch1 decoy variants, Notch1 decoys 1-13 and 10-24, act as ligand-specific Notch inhibitors. Notch1 decoy 1-13 is Dll4-specific whereas Notch1 decoy 10-24 is Jag1-specific. Ligand-specific Notch1 decoys effectively reduce tumor growth in tumor xenograft models in the mouse, including Mm5MT-FGF4, KP1-VEGF, LLC, and B16-F10. Notch1 decoy 1-13 has been demonstrated to increase tumor vasculature by increasing endothelial sprouting and number of tip cells. However, similar to the previously reported effects of Dll4 blockade, the tumor vessels are poorly perfused and hardly functional. On the other hand, Jag1-specific Notch1 decoy 10-24 significantly reduces tumor vessel density and disrupting endothelial-pericyte interactions, causing the impaired vascular structure and attenuated vascular perfusion. In addition, Notch1 decoys 1-13, 10-24, and 1-24 show an anti-metastatic potential in causing a delay of lung metastasis in the B16-F10 tumor model. Unlike gamma-secretase inhibitors and Dll4-blocking agents, Notch1 decoys do not cause GI-associated toxicity or vascular neoplasms. Therefore, our Notch1 decoys may represent a novel alternative and may hold future promise for Notch-targeted cancer therapy.

Non-alcoholic steatohepatitis (NASH) is a chronic liver disease associated with the worldwide spread of obesity. NASH predisposes development of fibrosis and hepatocellular carcinoma (HCC), but has no approved therapy due to incomplete understanding of the pathogenesis. Notch signaling normally specifies cell fate during development, but here we investigate how this pathway becomes dysregulated in NASH and contributes to fibrosis and cancer. In the first study, we show that hepatocyte Notch activity tracks with disease severity and treatment response in NASH patients, and is similarly increased in a mouse model of diet-induced NASH and liver fibrosis. Different genetic models demonstrate causatively that hepatocyte Notch induces liver fibrosis via secretion of the fibrogenic factor Osteopontin that activates hepatic stellate cells (HSCs), while pharmacologic inhibition of hepatocyte Notch could ameliorate NASH-associated fibrosis. In the second study, we research how hepatocyte Notch activation leads to HCC in mice on NASH diet. Transcriptomic analysis reveals nerve growth factor (NGF) as a Notch target gene in hepatocytes, and the abundance of hepatocyte NGF precursor protein (proNGF) is uniquely associated with HCC. We provide evidence that proNGF may facilitate HCC growth and expansion in a non-cell autonomous manner by inducing HSC deactivation and fibrosis remodeling. In summary, hepatocyte Notch maladaptively contributes to fibrogenesis and possibly HCC expansion by directly signaling to HSCs at different stages of NASH progression, and could be an accessible target for treatment of NASH-associated liver pathologies.

Man, Cheuk Him. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 219-263). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.vi / Table of Contents --- p.vii / List of Figures --- p.xii / List of Tables --- p.xvi / List of Publications --- p.xvii / Chapter Ch.l --- Introduction --- p.1 / Chapter 1.1 --- Aim of study --- p.1 / Chapter 1.2 --- Literature review --- p.3 / Chapter 1.2.1 --- Nasopharyngeal carcinoma (NPC) --- p.3 / Chapter 1.2.1.1 --- Structure and function of nasopharynx --- p.3 / Chapter 1.2.1.2 --- Histopathology of NPC --- p.3 / Chapter 1.2.1.3 --- Epidemiology of NPC --- p.4 / Chapter 1.2.2 --- Etiology of NPC --- p.6 / Chapter 1.2.2.1 --- Genetic factors --- p.6 / Chapter 1.2.2.2 --- Environment factors --- p.13 / Chapter 1.2.2.3 --- Epstein-Barr virus (EBV) infection --- p.14 / Chapter 1.2.3 --- Therapeutic treatment of NPC --- p.24 / Chapter 1.2.3.1 --- Radiotherapy (RT) --- p.24 / Chapter 1.2.3.2 --- Chemotherapy --- p.25 / Chapter 1.2.4 --- Notch signaling pathway --- p.26 / Chapter 1.2.4.1 --- Notch receptors and their ligands --- p.26 / Chapter 1.2.4.2 --- Activation of Notch signaling pathway --- p.29 / Chapter 1.2.4.3 --- Regulators of Notch signaling pathway --- p.32 / Chapter 1.2.4.4 --- Effectors of Notch signaling pathway --- p.32 / Chapter 1.2.5 --- Role of Notch signaling pathway in tumorigenesis --- p.33 / Chapter 1.2.5.1 --- Cell proliferation --- p.34 / Chapter 1.2.5.2 --- Cell survival --- p.35 / Chapter 1.2.5.3 --- Angiogenesis --- p.36 / Chapter 1.2.5.4 --- Cell invasion and metastasis --- p.36 / Chapter 1.2.6 --- Notch and oncogenic virus --- p.37 / Chapter 1.2.7 --- Crosstalk between Notch and other signaling pathways --- p.38 / Chapter 1.2.7.1 --- NFkB signaling pathway --- p.38 / Chapter 1.2.7.2 --- Ras signaling pathway --- p.39 / Chapter 1.2.7.3 --- Wnt signaling pathway --- p.40 / Chapter 1.2.7.4 --- Akt signaling pathway --- p.40 / Chapter 1.2.7.5 --- ErbB2 signaling pathway --- p.41 / Chapter 1.2.8 --- Notch as therapeutic target for cancer --- p.41 / Chapter Ch.2 --- Materials and Methods --- p.45 / Chapter 2.1 --- "Cell lines, xenografts and primary tumors" --- p.45 / Chapter 2.1.1 --- Cell lines --- p.45 / Chapter 2.1.2 --- Xenografts --- p.46 / Chapter 2.1.3 --- Primary tumors --- p.48 / Chapter 2.2 --- Reverse-transcription polymerase chain reaction (RT-PCR) --- p.50 / Chapter 2.2.1 --- Sample preparation for RT-PCR --- p.50 / Chapter 2.2.1.1 --- RNA extraction --- p.50 / Chapter 2.2.1.2 --- Quantitation of total RNA --- p.50 / Chapter 2.2.2 --- Conventional RT-PCR --- p.51 / Chapter 2.2.3 --- Quantitative RT-PCR --- p.51 / Chapter 2.3 --- Western immunoblot --- p.55 / Chapter 2.3.1 --- Protein extraction --- p.55 / Chapter 2.3.2 --- SDS-PAGE and immunoblotting --- p.55 / Chapter 2.4 --- Immunohistochemistry --- p.59 / Chapter 2.5 --- Cloning and plasmid DNA preparation --- p.62 / Chapter 2.5.1 --- Polymerase chain reaction (PCR) and purification of PCR products --- p.62 / Chapter 2.5.2 --- Restriction enzyme double digestion --- p.65 / Chapter 2.5.3 --- Ligation of plasmid and insert sequence --- p.65 / Chapter 2.5.4 --- Bacterial transformation --- p.66 / Chapter 2.5.5 --- Plasmid DNA extraction --- p.66 / Chapter 2.5.6 --- DNA sequencing --- p.67 / Chapter 2.6 --- Transient transfection of NPC cell lines --- p.67 / Chapter 2.7 --- Drug treatment on NPC cell lines --- p.69 / Chapter 2.8 --- Cell proliferation assays --- p.71 / Chapter 2.8.1 --- WST-1 assay --- p.71 / Chapter 2.8.2 --- BrdU assay --- p.71 / Chapter 2.9 --- Flow cytometry analysis --- p.72 / Chapter 2.9.1 --- Sample preparation --- p.72 / Chapter 2.9.2 --- Cell cycle analysis by propidium iodide staining --- p.73 / Chapter 2.9.3 --- Apoptosis analysis by AnnexinV-PI staining --- p.73 / Chapter 2.10 --- Apoptosis analysis by Caspase-3 activity assay --- p.74 / Chapter 2.11 --- RBP-Jk reporter assay --- p.75 / Chapter 2.12 --- NFKB1 reporter assay --- p.77 / Chapter 2.13 --- Dual luciferase reporter assay --- p.77 / Chapter 2.14 --- Expression array --- p.78 / Chapter 2.15 --- Statistical analysis --- p.79 / Chapter Ch.3 --- Characterization of Notch Signaling Molecules in NPC --- p.80 / Chapter 3.1 --- Introduction --- p.80 / Chapter 3.2 --- Results --- p.81 / Chapter 3.2.1 --- "Expression of Notch ligands, receptors, effectors and regulators in NPC cell lines and xenografts" --- p.81 / Chapter 3.2.2 --- "Expression of Notch ligands, receptors, regulators and effectors in NPC primary tumors" --- p.104 / Chapter 3.3 --- Discussion --- p.111 / Chapter 3.3.1 --- Overexpression of Jagl and D114 in NPC --- p.112 / Chapter 3.3.2 --- Overexpression of Notch receptors in NPC --- p.114 / Chapter 3.3.3 --- "Downregulation of Negative regulator, Numb, in NPC" --- p.116 / Chapter 3.3.4 --- Overexpression of Notch effectors in NPC --- p.117 / Chapter 3.4 --- Summary --- p.119 / Chapter Ch.4 --- Mechanisms of Activation of Notch Signaling Pathway in NPC --- p.120 / Chapter 4.1 --- Introduction --- p.120 / Chapter 4.2 --- Results --- p.122 / Chapter 4.2.1 --- EBV mediated Notch activation --- p.122 / Chapter 4.2.1.1 --- No effect of EBERs and EBNA1 on the expression of Notch Components --- p.122 / Chapter 4.2.1.2 --- LMP1 induces expression of Notch components --- p.129 / Chapter 4.2.1.3 --- LMP2A induces expression of Notch components --- p.133 / Chapter 4.2.2 --- Effect of CXCR4 on Notch signaling pathway in C666-1 --- p.137 / Chapter 4.3 --- Discussion --- p.139 / Chapter 4.3.1 --- EBV-mediated induction of Notch components --- p.139 / Chapter 4.3.2 --- Regulation of Notch expression by CXCR4 signaling pathway --- p.142 / Chapter 4.4 --- Summary --- p.145 / Chapter Ch.5 --- Investigation of the Oncogenic Role of Notch3 --- p.146 / Chapter 5.1 --- Introduction --- p.146 / Chapter 5.2 --- Results --- p.148 / Chapter 5.2.1 --- Effect of knockdown Notch 1 by siRNA on the growth of C666-1 --- p.148 / Chapter 5.2.2 --- Effect of knockdown Notch3 by siRNA on the growth of C666-1 --- p.151 / Chapter 5.2.2.1 --- Effect of knockdown Notch3 by siRNA on the RBP-Jk promoter activity of C666-1 --- p.153 / Chapter 5.2.2.2 --- Effect of knockdown Notch3 by siRNA on the proliferation of C666-1 --- p.155 / Chapter 5.2.2.3 --- Effect of knockdown Notch3 by siRNA on cell cycle progression of C666-1 --- p.158 / Chapter 5.2.2.4 --- Effect of knockdown Notch3 by siRNA on resistant to apoptosis in C666-1 --- p.160 / Chapter 5.2.3 --- Investigation of the anti-proliferation effect of therapeutic agents targeting Notch signaling pathway in NPC cells --- p.168 / Chapter 5.2.3.1 --- "Effect of DAPT on the proliferation of HEK293T, C666-1 and HK-1" --- p.168 / Chapter 5.2.3.2 --- Effect of AMD3100 on Notch signaling pathway and proliferation of NPC cells --- p.172 / Chapter 5.2.4 --- Study of downstream targets of Notch3 in NPC cells --- p.178 / Chapter 5.3 --- Discussion --- p.200 / Chapter 5.3.1 --- Oncogenic role of Notch3 in C666-1 --- p.200 / Chapter 5.3.2 --- Potential therapeutic approach in treating NPC via Notch inhibition --- p.206 / Chapter 5.3.2.1 --- "Gamma secretase inhibitor, DAPT" --- p.206 / Chapter 5.3.2.2 --- "CXCR4 antagonist, AMD3100" --- p.207 / Chapter 5.4 --- Summary --- p.209 / Chapter Ch.6 --- General Discussion --- p.210 / Chapter Ch.7 --- Conclusion --- p.217 / Reference --- p.219 / Appendices --- p.263 / Appendix 1 Summary of immunohistochemical staining results on 23 primary NPC samples --- p.264 / Appendix 2 Summary of 581 selected genes from the expression array --- p.265

Indiana University-Purdue University Indianapolis (IUPUI) / The heart is a complex organ that is composed of numerous cell types, which must integrate their programs for proper specification, differentiation, and cardiac morphogenesis. During cardiac development the basic helix-loop-helix transcription factor Hand2 is dynamically expressed within the endocardium and extra-cardiac lineages such as the epicardium, cardiac neural crest cells (cNCCs), and NCC derived components of the autonomic nervous system. To investigate Hand2 function within these populations we utilized multiple murine Hand2 Conditional Knockout (H2CKO) genetic models. These studies establish for the first time a functional requirement for Hand2 within the endocardium, as several distinct phenotypes including hypotrabeculation, tricuspid atresia, aberrant septation, and precocious coronary development are observed in endocardial H2CKOs. Molecular analyses reveal that endocardial Hand2 functions within the Notch signaling pathway to regulate expression of Nrg1, which encodes a crucial secreted growth factor. Furthermore, we demonstrate that Notch signaling regulates coronary angiogenesis via Hand2 mediated modulation of Vegf signaling. Hand2 is strongly expressed within midgestation NCC and endocardium derived cardiac cushion mesenchyme. To ascertain the function of Hand2 within these cells we employed the Periostin Cre (Postn-Cre), which marks cushion mesenchyme, a small subset of the epicardium, and components of the autonomic nervous system, to conditionally ablate Hand2. We find that Postn-Cre H2CKOs die shortly after birth despite a lack of cardiac structural defects. Gene expression analyses demonstrate that Postn-Cre ablates Hand2 from the adrenal medulla, causing downregulation of Dopamine Beta Hydroxylase (Dbh), a gene encoding a crucial catecholaminergic biosynthetic enzyme. Electrocardiograms demonstrate that 3-day postnatal Postn-Cre H2CKO pups exhibit significantly slower heart rates than control littermates. In conjunction with the aforementioned gene expression analyses, these results indicate that loss of Hand2 function within the adrenal medulla results in a catecholamine deficiency and subsequent heart failure.