Emerging evidence indicates that 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) and computed tomography (CT) are useful imaging modalities for evaluating tumor progression in transgenic mouse models of solid human cancers, but the potential of integrated FDG-PET/CT for assessing tumor development in genetically engineered mouse models of liquid human cancers - including neoplasms of immunoglobulin (Ig)-producing plasma cells - has not been established. Here we use a double-transgenic strain of laboratory mice, designated C.IL6Myc, that recapitulates key features of human plasma cell myeloma (a.k.a. multiple myeloma [MM]) to demonstrate that FDG-PET/CT affords a useful research tool for assessing plasma cell tumor (PCT) development in a serial, objective and, importantly, stage- and lesion-specific manner. Supported by serum biomarker analyses (Ig level, paraprotein) and histopathological findings in C.IL6Myc mice undergoing PCT development, the newly generated FDG-PET/CT data set demonstrates the potential of this imaging modality for preclinical basic and translational MM research. PET imaging of genetically engineered mice in which MM-like tumors arise predictably in an intact immunocompetent microenvironment may facilitate the design and testing of new approaches to the treatment and prevention of MM in humans.

Alzheimers disease (AD) is defined as a progressive neurodegenerative disorder that gradually destroys a persons memory and ability to learn. There are three pathological hallmarks of the disease which are necessary for diagnosis of AD, these are; extracellular amyloid plaques composed of [beta]-amyloid (A[beta]) protein, intracellular neurofibrillary tangles and neuronal loss. Amyloid plaques exist as both compact deposits which stain with Congo red and more numerous diffuse deposits. Active immunization against A[beta] 1-42 or passive immunization with monoclonal anti-A[beta] antibodies reduces amyloid deposition and improves cognition in APP transgenic mice. Over several studies of active immunization in APP+PS1 transgenic mice we showed a strong correlation between reduction of compact amyloid deposits and the degree of microglial activation suggesting a potential role of microglia in the removal of A[beta]. Injection of anti-A[beta] antibodies into the frontal cortex and hippocampus of aged APP transgenic mice revealed an early phase of A[beta] removal which was removal of only diffuse amyloid deposits with no associated activation of microglia. A later phase was the removal of compact amyloid deposits. This was associated with significant activation of microglia. Prevention of this microglial activation by anti-A[beta] F(ab)2 fragments or its inhibition by dexamethasone also precluded the removal of compact amyloid deposits but did not affect the removal of the diffuse deposits. Systemic injection of anti-A[beta] antibodies weekly over a period of 1, 2, 3 and 5 months transiently activated microglia associated with the removal of compact amyloid deposits and elevated plasma A[beta], suggesting a peripheral mechanism contributes to removal of brain A[beta]. This systemic administration also dramatically improved cognitive performance in the Y-maze and in the radial-arm water maze. These studies also showed a significant increase in vascular amyloid dependent on the number of antibody injections the mice received. Associated with this increase in vascular amyloid was a dramatic increase in the numbers of microhemorrhages in the brain. Despite this pathology the mice showed cognitive improvement with the treatment. These effects could have major ramifications in humans and should be further investigated prior to any human clinical trials.

The gene PTPN11 was identified in the early 1990s, and encodes the non-transmembrane protein tyrosine phosphatase SHP2. SHP2 is expressed ubiquitously in cells, and plays an important role in cancer. Unlike most phosphatases, SHP2 positively regulates several signaling pathways including the Ras/MAPK and Src signaling pathways and acts as a proto-oncogene. SHP2 is also a cancer essential gene in certain types of carcinomas, and promotes growth, survival, and epithelial to mesenchymal transformation. Gain of function (GOF) SHP2 mutations are known leukemic oncogenes, and have been identified to a smaller extent in solid tumors as well. Currently, the roles of SHP2 in lung carcinoma are not fully understood. While GOF SHP2 mutations have been detected in lung cancer, their contributions to cellular transformation had not been established. In addition, SHP2 is known to promote EGF growth factor receptor (EGFR) signaling. Since GOF EGFR mutations induce transformation of lung epithelial cells, it is possible that SHP2 plays a role in promoting GOF EGFR mutant driven tumorigenesis. The objective of this dissertation is to determine whether SHP2 can act as an oncogene in lung epithelial cells and whether SHP2 inhibition can affect GOF EGFR mutant induced lung cancer. To achieve these aims, we generated two novel doxycycline (Dox) inducible transgenic mouse models which express either the GOF SHP2E76K leukemic oncogene or the dominant negative SHP2CSDA mutant under the control of the Clara cell secretory protein (CCSP) promoter to regulate transgene expression to type II pneumocytes. To determine whether SHP2 plays a role in promoting GOF EGFR mutant signaling, we started by disrupting SHP2 function in vitro. Two non small lung cancer cell lines were used for this project: HCC827 carries the LREA deletion in exon 19, and H1975 co-expresses the EGFRL858R point mutation and the EGFRT790M gatekeeper mutation. After SHP2 PTP inhibition or knock-down by shRNA and siRNA, both cell lines exhibited decreased cell proliferation and reduced levels of pErk1/2 and c-Myc. Based on these results, we acquired a transgenic mouse line which expresses the EGFRL858R mutant under the control of the tet-O promoter and generated bitransgenic CCSP-rtTA/tetO-EGFRL858R and tritransgenic CCSP-rtTA/tetO-EGFRL858R/tetO-SHP2CSDA mice to study the effects of the dominant negative SHP2CDSA mutant on EGFRL858R mediated carcinogenesis in vivo. After 4, 6, and 8 weeks of Dox induction, pErk1/2 and pSrc levels were increased in the lungs of bitransgenic mice compared to wild type controls. Both kinases were suppressed by SHP2CSDA expression in tritransgenic mice. In addition, SHP2CSDA expression delayed tumor onset and prevented progression to a more aggressive phenotype. Tritransgenic mice also developed a smaller tumor burden compared to bitransgenic animals. These results suggest that SHP2 is critical for GOF EGFR mutant mediated lung tumorigenesis and describe a new role of SHP2 as a potential therapeutic target for the development of novel NSCLC drugs. Once we generated our CCSP-rtTA/tetO-SHP2E76K transgenic mouse model, we administered Dox for one month and found that SHP2E76K expression upregulates pErk1/2, pSrc, pGab1, c-Myc and Mdm2 levels in the lungs of bitransgenic mice compared to controls. After six to nine months of Dox induction, SHP2E76K expression caused formation of lung adenomas and adenocarcinoma. We then took advantage of the reversible feature of our mouse model to test whether lung tumors are dependent on sustained SHP2E76K expression for survival. MRI analysis of lung adenocarcinomas showed full regression of the lung tumors after Dox withdrawal. Histological evaluation of lung tissues revealed residual hyperplastic lesions as well as evidence of necrosis, while biochemical analysis showed that pGab1, pErk1/2, pSrc and c-Myc returned to basal levels. These results demonstrate that sustained SHP2E76K expression is required for lung tumor maintenance. Moreover, this data describe a novel function of SHP2E76K as an oncogene in lung carcinoma.

Abstract not available

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Thesis (M. Phil.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Includes list of papers and publications by the author Includes bibliographical references (leaves 198-231) Reports on studies aimed at increasing the efficiency of livestock transgenesis programs. Overall the experiments provide an improved basis for understanding the application of animal biotechnology to the pig.

Graduation date: 1995

Le tissu adipeux, outre son rôle de réserve énergétique, joue un rôle essentiel dans le contrôle de l'homéostasie du métabolisme ainsi que dans la physiopathologie de différentes affections, telles que diabète de type 2, dyslipidémies ou athérosclérose. Ce rôle est en partie assuré par des substances sécrétées par le tissu adipeux dans le plasma et regroupées sous le terme d'adipokines. Il s'agit notamment du tumor necrosis factor (TNF)-α, de la leptine, résistine ou encore de l'adiponectine (ApN). L'ApN se distingue des autres adipokines car, contrairement à l'augmentation des concentrations plasmatiques de leptine, de résistine ou de TNF-α observée dans l'obésité, ses taux sont corrélés de façon négative à l'indice de masse corporelle et de façon positive à la sensibilité à l'insuline. L'ApN joue donc un rôle très important dans la modulation du métabolisme lipidique et glucidique et/ou dans la régulation de l'insulinosensibilité. Afin d'étudier les répercussions in vivo d'une expression précoce et chronique d'ApN spécifiquement dans le tissu adipeux, nous avons créé des souris transgéniques où l'ADNc de l'ApN (forme complète) a été placé sous contrôle d'un promoteur adipocytaire. Selon le nombre de copies du transgène intégré dans le génome, nous obtenons des phénotypes forts différents, voire opposés. Dans notre étude réalisée chez des souris ayant intégré un nombre modeste de copies du transgène (6 copies), nous observons une diminution de l'expression (ARNm) et du contenu protéique en ApN du tissu adipeux. Ce rétrocontrôle négatif de la production d'ApN est associé à un phénotype d'intolérance au glucose et d'insulinorésistance, à une adiposité accrue probablement suite à la faible expression des molécules impliquées dans la dissipation d'énergie et à l'accroissement de la lipogenèse. Nous assistons également à une faible expression d'AdipoR2, l'isoforme du récepteur responsable de l'action de l'ApN sous sa forme complète. A l'inverse, les souris ayant intégré un grand nombre (100) de copies du transgène présentent une augmentation de l'expression et du contenu en ApN dans différents sites du tissu adipeux blanc (le phénomène de rétrocontrôle de l'ApN endogène étant masqué par une surexpression plus prononcée de l'ApN exogène). Cette surexpression d'ApN est associée à une amélioration attendue de l'homéostasie glucidique et du profil lipidique. De plus, ces souris présentent une nette réduction de leur adiposité secondaire à une augmentation de la dépense énergétique et, fait original, à une diminution de la différenciation adipocytaire. Le remaniement du tissu adipeux résulte en de petits adipocytes, caractérisés par une diminution d'expression des enzymes lipogéniques et de marqueurs adipocytaires, ainsi que par une augmentation d'expression de protéines découplantes et d'un marqueur préadipocytaire (Pref-1). Chez ces souris, l'expression d'AdipoR2 est accrue, peut-être suite à une réduction locale de TNFα. / Adipose tissue regulates fuel homeostasis and is implicated in the pathophysiology of several components of the metabolic syndrome, such as diabetes of type 2, dyslipidemia or atherosclerosis. The secretion of regulatory peptides, often referred to as adipocytokines, mediates in part these adipose functions. The best-known adipokines include tumor necrosis factor α (TNFα), leptin, resistin and adiponectin (ApN). Unlike the other adipokines, which are elevated in obesity, plasma ApN levels are negatively correlated to body mass index and positively to insulin sensitivity. Thus, ApN plays a fundamental role in regulating lipid and glucose metabolism, and insulin action. To study in vivo the chronic effects of ApN specifically on adipose tissue, we generated transgenic mouse lines allowing persistent and moderate expression of native full-length ApN targeted to white adipose tissue. We have obtained two different phenotypes according to the number of transgene copies integrated into the genome In our mouse lines with a modest copy number (6), we observed a decrease of expression (ARNm) and protein content of ApN in adipose tissue. This negative feedback on ApN production was associated with a phenotype of the glucose intolerance and insulin resistance, and with an increased adiposity due to low expression of molecules involved in energy expenditure, and to increased lipogenesis. We also observed a weak expression of AdipoR2, the receptor isoform responsible for the action of full-length ApN. On the contrary, mice with a high copy number (100), clearly overexpressed ApN in various sites of white fat (the downregulation of endogenous ApN being masked by the marked overexpression of exogenous ApN). This overexpression of ApN was associated with an expected improvement of glucose homeostasis and lipid profile. Furthermore, these mice showed reduced adiposity, due to increased energy expenditure and decreased adipocyte differentiation. Adipose tissue remodelling resulted in smaller (younger) adipocytes, characterized by a decrease of lipogenic enzymes and of adipocyte markers, as well as by an increased expression of uncoupling proteins and a preadipocyte marker (Pref-1). In this group of mice, the expression of AdipoR2 was enhanced possibly because of a local reduction of TNFα.