The dynamics of cell signalling are critical to cell fate decisions. Human Epidermal growth factor Receptors (HERs)-mediated Ras/Raf/MEK/ERK and PI3K/Akt signalling cascades relay extracellular signals from the plasma membrane to targets in the nucleus and cytoplasm and play pivotal roles in cell fate determination including proliferation, differentiation and cell survival. Both pathways, once activated, are further regulated by complex feedback loops which may exert either positive or negative effects on cascade components and can result in signalling oscillation. In this study, heregulin (HRG) - and epidermal growth factor (EGF)- stimulated oscillation of both p-ERK1/2 and p-Akt expression in breast cancer cell lines was demonstrated. The oscillation was cell line dependent and was observed in MCF-7 and MCF-7/HER2-18 cells but not in BT474 cells. The oscillation was augmented by cycloheximide implicating transcriptional involvement. Gene expression analysis identified 29 genes as possible candidates involved in the transcriptional feedback regulation. Apart from the feedback regulation, feedforward regulation was also observed. To expedite the analyses In-cell Western and Reverse Phase Protein Array (RPPA) assays were developed. A scheme of transcriptional feedback loops regulating the oscillation in the ERK1/2 pathway is proposed, including negative feedback loops to ERK1/2 from DUSPs, early positive and late negative feedback loops to MEK1/2 and positive feedback loops to HER-3 from AREG, HB-EGF, CYR61 and CTGF. Two HER-2-targeted inhibitory monoclonal antibodies were investigated – trastuzumab and pertuzumab. Trastuzumab not only inhibited the growth of HER-2 over-expressing MCF-7/HER2- 18 cells and BT474 cells but also that of EGF-driven MCF-7 cells which expressed low/moderate HER-2 levels. Pertuzumab blocked the growth of both MCF-7 and MCF-7/HER2-18 driven by either EGF or HRG. When used in combination with trastuzumab, pertuzumab had much more potent activity in inhibiting cell growth and signalling than either single drug. Trastuzumab and pertuzumab had opposing effects on immediate p-ERK1/2 signalling and trastuzumab’s effects on signalling could be mimicked by the PI3K inhibitor LY294002. PTPN13, a non-receptor type tyrosine protein phosphatase, is a proposed tumour suppressor in breast cancer. This was investigated as a candidate regulator of the signalling oscillation and although not observed as a transcriptional modulator of the oscillation, its high expression level was observed to be associated with cell growth inhibition in MCF-7/HER2-18 cells by trastuzumab. Moreover, immunohistochemical analysis of 121 clinical tumours which had received trastuzumab treatment revealed the correlation between the expression level of PTPN13 and the mutation status of PIK3CA. In conclusion, the observed oscillation may contribute to the elucidation of the complex regulation of signalling pathways, which is vital to the different cell fate decision made through the same core pathway. The synergy between trastuzumab and pertuzumab supports the clinical use of the combination treatment and suggested PI3K/Akt pathway as the major pathway in controlling tumour growth.

Yung, Kam Fai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 107-129). / Abstracts in English and Chinese. / ABSTRACT --- p.ii / 摘要 --- p.iv / ACKNOWLEDGEMENTS --- p.vi / TABLE OF CONTENTS --- p.vii / PUBLICATION --- p.ix / LIST OF TABLES --- p.x / LIST OF FIGURES --- p.xi / LIST OF ABBREVIATIONS --- p.xii / Chapter SECTION I: --- BACKGROUND --- p.1 / Chapter CHAPTER 1: --- "The biology, diagnostics and management of lung cancer" --- p.2 / Chapter 1.1 --- "Basic biology, classification and diagnostics" --- p.2 / Chapter 1.1.1 --- Epidemiology and etiology of lung cancer --- p.2 / Chapter 1.1.2 --- Clinical Presentation and Diagnostics of Lung Cancer --- p.3 / Chapter 1.2 --- Treatment of lung cancer --- p.9 / Chapter 1.2.2 --- Radiotherapy --- p.10 / Chapter 1.2.3 --- Chemotherapy --- p.11 / Chapter CHAPTER 2: --- Epidermal Growth Factor Receptor Mutations in Lung Cancer --- p.13 / Chapter 2.1 --- The Epidermal Growth Factor Receptor --- p.13 / Chapter 2.2 --- Overexpression of EGFR in NSCLC --- p.14 / Chapter 2.3 --- The development of EGFR inhibitors --- p.15 / Chapter 2.3.1 --- Monoclonal Antibodies --- p.16 / Chapter 2.3.2 --- Small-molecule inhibitors --- p.17 / Chapter 2.3.2.1 --- Gefitinib --- p.17 / Chapter 2.3.2.2 --- Erlotinib --- p.19 / Chapter 2.3.2.3 --- Other small-molecule inhibitors --- p.20 / Chapter 2.4 --- Mutations of EGFR in NSCLC --- p.21 / Chapter 2.4.1 --- Activating Mutations conferring sensitivity to tyrosine kinase inhibitors --- p.21 / Chapter 2.4.2 --- Secondary mutations associated with resistance to tyrosine kinase inhibitors --- p.23 / Chapter 2.5 --- EGFR gene amplification --- p.24 / Chapter 2.6 --- Detection of EGFR mutations --- p.25 / Chapter 2.7 --- Aim of the thesis --- p.31 / Chapter SECTION II: --- DETECTION OF EGFR MUTATIONS IN TUMOR AND PLASMA SAMPLES BY MASS SPECTROMETRY AND DIGITAL PCR --- p.33 / Chapter CHAPTER 3: --- Detection of EGFR mutations by mass spectrometric methods --- p.34 / Chapter 3.1 --- Introduction --- p.34 / Chapter 3.1.1 --- Principles of Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) --- p.34 / Chapter 3.1.2 --- The MassARRAY Homogenous MassEXTEND (hME) assay --- p.35 / Chapter 3.1.3 --- The Single-Allele Base Extension Reaction (SABER) and the Allele-Specific Base Extension Reaction (ASBER) --- p.36 / Chapter 3.2 --- Materials and Methods --- p.36 / Chapter 3.2.1 --- The protocol for the detection of EGFR exon 21 point mutation by Mass Spectrometric Methods --- p.37 / Chapter 3.3 --- Results --- p.42 / Chapter 3.4 --- Discussion --- p.49 / Chapter CHAPTER 4: --- Evaluation of the detection limit and sensitivity of the digital PCR assays --- p.51 / Chapter 4.1 --- Introduction --- p.51 / Chapter 4.1.1 --- The theoretical basis of digital PCR quantification and the relationship with the Poisson distribution --- p.51 / Chapter 4.1.2 --- Assessment of Assay Detection Limit --- p.54 / Chapter 4.1.3 --- Comparing Digital PCR with sequencing after conformation sensitive gel electrophoresis (CSGE) --- p.59 / Chapter 4.2 --- Materials and Methods --- p.59 / Chapter 4.2.1 --- Design of digital PCR assay for the detection of EGFR exon21 L858R point mutation --- p.59 / Chapter 4.2.2 --- Design of digital PCR assay for the detection of EGFR exon19 deletion --- p.60 / Chapter 4.2.3 --- The protocols of digital PCR assays for EGFR mutation detection --- p.64 / Chapter 4.2.4 --- Single molecule detection test --- p.65 / Chapter 4.2.5 --- Artificial mixtures of mutant and wild-type DNA --- p.66 / Chapter 4.2.6 --- Sequencing after CSGE --- p.66 / Chapter 4.3 --- Results --- p.67 / Chapter 4.3.1 --- Results of the single molecule detection test and artificial mixture analysis --- p.67 / Chapter 4.3.2 --- Results of CSGE and sequencing compared with digital PCR --- p.73 / Chapter 4.4 --- Discussion --- p.75 / Chapter CHAPTER 5: --- Detection of EGFR mutations in prospectively collected tumor samples of NSCLC patients --- p.77 / Chapter 5.1 --- Introduction --- p.77 / Chapter 5.2 --- Materials and Methods --- p.78 / Chapter 5.2.1 --- Sample preparation and DNA extraction of tumor tissues --- p.78 / Chapter 5.3 --- Results --- p.79 / Chapter 5.4 --- Discussion --- p.82 / Chapter CHAPTER 6: --- Detection of EGFR mutations in prospectively collected plasma samples of NSCLC patients --- p.85 / Chapter 6.1 --- Introduction --- p.85 / Chapter 6.2 --- Materials and Methods --- p.87 / Chapter 6.2.1 --- Sample preparation and DNA extraction of plasma samples --- p.87 / Chapter 6.3 --- Results --- p.88 / Chapter 6.3.1 --- Digital PCR analysis of EGFR mutations in plasma samples of NSCLC patient --- p.88 / Chapter 6.3.2 --- Variations in plasma EGFR mutation concentration after TKI treatment --- p.93 / Chapter 6.4 --- Discussion --- p.96 / Chapter SECTION III: --- CONCLUDING REMARKS --- p.100 / Chapter CHAPTER 7: --- Conclusion and future perspectives --- p.101 / Chapter 7.1 --- Mass spectrometric analysis --- p.101 / Chapter 7.2 --- Microfluidics Digital PCR --- p.102 / Chapter 7.3 --- Future perspectives --- p.105 / References --- p.107

Thesis (Ph. D.)--University of Oklahoma. / Bibliography: leaves 132-165.

Thesis (Ph. D.)--University of Virginia, 2008. / Title from title page. Includes bibliographical references. Also available online through Digital Dissertations.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 38-51).

L'hypervascularisation artérielle bronchique des dilatations des bronches contribue à l'afflux local de cellules inflammatoires et de protéines plasmatiques et favorise la survenue de saignements bronchiques. Les mécanismes de l'angiogénèse des vaisseaux bronchiques dans les dilatations des bronches sont peu connus, mais pourraient impliquer la voie du facteur de croissance endothélial (VEGF)-A.Nous avons émis l'hypothèse que l'infection bronchique dans les dilatations des bronches contribue à l'angiogénèse des vaisseaux bronchiques. Nous avons développé chez la souris un modèle d'infection bronchique persistante par l'instillation intratrachéale de billes d'agarose contenant du Pseudomonas aeruginosa. Nos résultats indiquent que l'infection bactérienne provoque l'angiogénèse des vaisseaux péribronchiques en 7 jours. P. aeruginosa induit la synthèse de VEGF-A par l'épithélium respiratoire in vitro et chez la souris par l'activation du récepteur de l'epidermal growth factor (EGF).Nous avons ensuite évalué l'effet de la perte de fonction de CFTR, l'anomalie caractéristique de la mucoviscidose (une cause génétique de dilatation des bronches), sur l'angiogénèse bronchique et l'expression de facteurs pro-angiogéniques. Ces études ont été menées à partir de poumons de patients mucoviscidosiques, chez des souris mutées pour le gène cftr et par inhibition de CFTR sur des cultures de cellules épithéliales.Nos données indiquent que l'infection bronchique contribue à l'angiogénèse péribronchique, qui nécessiterait une communication épithélium/endothélium. L'épithélium bronchique de la mucoviscidose est dans un état pro-angiogénique en l'absence d'infection. / Abnormal proliferation of bronchial arteries in subjects with bronchiectasis contributes to the recruitment of inflammatory cells and plasma protein within the airways, and promotes endobronchial bleeding. Mechanisms of bronchial angiogenesis in bronchiectasis are largely unknown, but could implicate the vascular endothelial growth factor (VEGF)-A pathway.We hypothesized that bronchial infection that occurs in bronchiectasis contributes to angiogenesis of bronchial blood vessels. We developed a mouse model of persistent bronchial infection by intratracheal instillation of agarose beads containing Pseudomonas aeruginosa. Our results indicate that bacterial infection promotes angiogenesis of peribronchial blood vessels within 7 days. Further, P. aeruginosa induces VEGF-A synthesis in airway epithelium in vitro and in mouse in vivo via activation of the epidermal growth factor (EGF) receptor.Next we examined the role of CFTR defect, associated with cystic fibrosis (CF, a genetic cause of bronchiectasis), on bronchial angiogenesis and expression angiogenic growth factors. These studies were conducted using lung tissues obtained in CF subjects, in various strains of mice mutated for the cftr gene, and by inhibition of CFTR function in cultured airway epithelial cells.Our data indicate that bronchial infection contributes to peribronchial angiogenesis, which probably necessitate interaction of epithelial and endothelial cells. Cystic fibrosis airway epithelium may exhibit a pro-angiogenic phenotype in the absence of infection.

<p>Collagen crosslinking with a polypropyleneimine octaamine dendrimers, via carbodiimide chemistry, was further exploited to demonstrate the ability of this technology for various tissue engineering strategies, including tissue engineered corneal equivalents (TECE) and blood-contacting biomaterials. In addition, modification with extracellular matrix components and other biomimetic molecules may enhance tissue-host interactions for greater <em>in vivo </em>compatibility.</p> <p>First, the efficacy of the dendrimer crosslinking technology was further validated with commercially available collagen-based materials, from bovine or human sources (Chapter 4: Paper 1), as determined via transmittance, water uptake, differential scanning calorimetry, collagenase stability and <em>in vitro </em>cell compatibility. Despite gel formation, the matrix integrity was compromised with collagen-based materials manufactured under acidic conditions and purified via freeze-drying.</p> <p>To continue the theme of dendrimer crosslinked collagen gels as TECE materials, growth factor incorporation was investigated with epidermal growth factor (EGF) and heparin-binding EGF (HB-EGF), as a method for improving device epithelialization and subsequent host integration. However, given the short half lives of these growth factors, an effective growth factor delivery system is necessary to protect growth factor bioactivity. As heparan sulphate proteoglycans sequester and release heparin-binding growth factors <em>in vivo</em>, the use of heparinized dendrimer crosslinked collagen (CHG) gels for HB-EGF delivery would provide prolonged, controlled delivery, while maintaining growth factor effectiveness (Chapter 5: Paper 2). HB-EGF release was prolonged and capable of inducing human cornea epithelial cell (HCEC) proliferation. Thus, HB-EGF delivery from CHG gels could aid in TECE device retention through enhanced device-host integration via epithelialization.</p> <p>Alternatively, tethering EGF or HB-EGF to dendrimer crosslinked collagen (CG) gels could also supply growth factor stimulation in a manner that maintains bioactivity, while stimulating growth factor receptors continually with minute concentrations (Chapter 6: Paper 3). Growth factor uptake and bioactivity was assessed with radiolabeled growth factor and through <em>in vitro </em>epithelial cell culture, respectively. Surface-modification of CG gels with growth factors demonstrated greater bioactivity, compared to growth factor bulk-modification of CG gels.</p> <p>Finally, dendrimer crosslinked collagen gels, with pre-activated heparin (PH gels) were investigated as a tissue engineered blood-contacting biomaterial (Chapter 7: Paper 4), as we hypothesized that biomaterial induced coagulation is not only influenced by an anticoagulant surface, but also by the underlying material and that improved blood-biomaterial interactions may be achieved by utilizing a natural polymer that emulates biomimetic properties. Pre-activation of heparin was utilized to increase heparin gel content, while antithrombotic properties were evaluated via antithrombin and fibrinogen adsorption and plasma recalcification times. PH gels had increased heparinization, but extensive crosslinking compromised antithrombin-heparin interactions, compared to CHG gels. CHG gels demonstrated improved antithrombotic properties and further evaluation of these gels for blood-contacting applications is warranted.</p> / Doctor of Philosophy (PhD)

published_or_final_version / Zoology / Doctoral / Doctor of Philosophy

published_or_final_version / Biochemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Paediatrics / Doctoral / Doctor of Philosophy