Nasopharyngeal carcinoma (NPC) has distinctive ethnic and geographic distributions, with the highest incidence in Southern China. Epstein-Barr virus (EBV) infection, non-viral environmental risk factors, and host genetics contribute to the development of NPC. In our previous studies, Fibulin-2 (FBLN2), located at chromosome 3p25.1, has been identified as a candidate tumor suppressor gene (TSG) in nasopharyngeal carcinoma (NPC) by using a chromosome 3 NotI genomic microarray screen, followed by functional assays. FBLN2 belongs to the fibulin family of extracellular matrix glycoproteins. It encodes a large protein consisting of cysteinerich and cysteine-free segments, three anaphylatoxin (AT) modules, a series of cbEGFlike repeated, and a fibulin module. Although FBLN2 was also identified as a candidate TSG in other cancers, its molecular characterization is still largely unknown. In the present study, lentiviral constitutive and inducible transgene expression systems, fluorescent protein labelling and reporter systems, and shRNA-mediated knockdown system were optimized and established for studies in NPC. With the use of lentiviral systems, the FBLN2-mediated signaling pathways and the functions of FBLN2-related p65 signaling pathway were revealed. Lentiviral pWPI-FBLN2 infected HONE1, HK1, and C666 cell lines consistently reduced p65 phosphorylation at serine S536. Also, FBLN2 was shown to inactivate RhoA and Cdc42, resulting in decreased stress fiber and filopodia formation. Full-length and truncated FBLN2 fragments, with the exception of anaphylatoxin module, reduced phosphorylation of p65 as well as suppressed HUVEC tube formation. The p65 pathway was then chosen for in-depth studies. Inactivation of p65 by p65 stable knockdown and IκBα super repressor overexpression showed reduced cell migration, invasion, angiogenesis, in vitro cell growth, and in vivo tumor growth. In contrast, overexpression of wild type p65 and phospho-mimic S536E p65 promotes cell migration, invasion, angiogenesis, in vitro cell growth, and cell cycle progression. Molecular studies suggested that tumorassociated angiogenesis is regulated by p65 through expression of pro-angiogenic factors and the p65 activity controls epithelial-to-mesenchymal transition (EMT)-like properties in NPC. Western blotting and qPCR analyses showed that inactivation of p65 reduced expression of pro-angiogenic factors and mesenchymal markers. Overexpression of p65 induced expression of pro-angiogenic factors and mesenchymal markers as well as enhanced EMT-like properties. The elimination of the p65 feedback mechanism by IκBα knockdown largely induced expression of pro-angiogenic factors and mesenchymal markers, as well as changes in cell morphology. In conclusion, these results suggest that FBLN2 suppresses tumor growth, tumor-associated angiogenesis, migration, and invasion through the regulation of Erk1/2, p65, and Rho GTPase pathways. The important roles of the p65 pathway in angiogenesis and EMT were also revealed. These findings provide a strategic new insight into the understanding of mechanistic role of FBLN2 in NPC and provide a better understanding for the molecular genetic basis of NPC tumorigenesis. / published_or_final_version / Clinical Oncology / Doctoral / Doctor of Philosophy

published_or_final_version / Microbiology / Master / Master of Philosophy

published_or_final_version / Anatomy / Master / Master of Philosophy

published_or_final_version / Radiation Oncology / Master / Master of Philosophy

published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy

Nasopharyngeal carcinoma (NPC) is an aggressive head and neck cancer ranked as the 5th most common in Hong Kong. We aimed to study the role of dynamic contrast-enhanced MRI (DCE-MRI) and dynamic 2-deoxy-2-[fluorine-18]fluoro -D-glucose positron emission tomography (FDG-PET) for characterizing NPC tumors in newly-diagnosed patients, and to quantitatively evaluate the intratumoral heterogeneity of NPC. In Chapter 2 we employed semi-quantitative analysis of DCE-MRI to study the dynamic enhancement pattern by analyzing the time-intensity curves in 25 NPC patients. Our findings suggested that high blood flow caused a high initial intensity enhancement rate (ER), and that neovasculature due to tumor angiogenesis in tumors of larger volume or higher T-stage caused more accumulation of contrast agent which can be detected by DCE-MRI. PET and semi-quantitative DCE-MRI parameters were not correlated and may reflect different physiological/molecular processes in the microenvironment of NPC tumor. However the major limitation of semi-quantitative analysis was that the physiological correlates of these parameters were unclear. In Chapter 3 we applied quantitative analysis of DCE-MRI to study the permeability and perfusion characteristics in the same cohort as in Chapter 2. Our findings implied that the permeability may be high compared to blood flow in NPC tumor. We also observed significant correlations between iAUC (the initial area under the time-intensity curve) by semi-quantitative analysis and ve (the volume fraction of extravascular extracellular space) by quantitative analysis, and between the two rate constants (kep’s) from these two methods, which showed that semi-quantitative analysis was a feasible alternative in reflecting the physiological characteristics of NPC. However, we did not observe any significant correlation between PET and DCE-MRI quantitative parameters, also suggesting that PET and DCE-MRI reflected different physiological information in NPC. In Chapter 4 we applied dynamic PET scan to study the glucose metabolism in 18 NPC tumors (16 included in DCE-MRI cohort). Our findings showed that the overall FDG uptake was mainly composed of the FDG in tissue compartment (Ki), which was governed by the phosphorylation (k3) but not the transport of FDG (K1). This finding may further indicate a potential role of the phosphorylation rate k3 in NPC. Dynamic PET parameters did not correlate with DCE-MRI, indicating that the two modalities reflect different molecular information in NPC. In Chapter 5, intratumoral heterogeneity in NPC tumors of 40 patients was studied using 18F-FDG PET scan. Our findings showed that as tumors grew to a larger volume and higher T-stage, they showed more heterogeneous glucose metabolism. It was found that more heterogeneous tumor was associated with worse disease-free survival, indicating that tumor metabolic heterogeneity may play an important role for NPC patient prognosis. To summarize, these results showed that DCE-MRI and dynamic PET improved our understanding about the physiological/molecular process of NPC, and, these two modalities reflected different physiological information in the microenvironment of NPC tumors. This indicated that the relationship between supply of nutrients such as glucose and blood flow/permeability is complex and not directly related. Moreover, intratumoral heterogeneity by PET scan was also of importance in prognostication. / published_or_final_version / Diagnostic Radiology / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--University of Hong Kong, 1995. / Includes bibliographical references.

published_or_final_version / abstract / Medicine / Master / Doctor of Medicine

Nasopharyngeal carcinoma (NPC) is the 7th commonest cancer in Hong Kong. Improvements in radiotherapy had increased the cure. Unfortunately, up to 10% of the patient still suffered from local recurrence. Because of the deep location, nasopharyngectomy was considered a difficult operation. Developments in surgical approaches had now established nasopharyngectomy as a standard salvage for locally recurrent NPC. With improvements of endonasal endoscopic instruments and endoscopic techniques, endoscopic nasopharyngectomy as a minimally invasive surgery for salvaging small locally recurrent NPC have been reported in several cohorts with encouraging results. Robotic nasopharyngectomy remained difficult due to tight operation space and instrument considerations. The da Vinci surgical robot was marketed in 1999 as a tool to assist surgeons in performing complex surgical manipulations in tight spaces. It was later adapted to be used in the upper aerodigestive tract for endoscopic resection of small cancers transorally. As the da Vinci surgical robot was not designed for head and neck operations, adaptations are required when we tried to apply it to resect tumours in the nasopharynx. The present study aimed to develop the use of the da Vinci surgical robot to perform minimally invasive operations on the nasopharynx in a cadaveric model. Ten procedures on 3 cadavers were performed with the surgical robot. Due to instrument clutter, a transoral approach was preferred over transnasal approach. In transoral approach, the soft palate obstructs the access to the nasopharynx. We devised three approaches, namely palatal suspension approach, midline palatal split approach and lateral palatal flap approach. We also assess the advantages and limitations of the three approaches. From 2010-2014, 18 robotic nasopharyngectomies were performed. Median operation time was 232 minutes (range 125-574). Estimated median blood loss was 100ml (range 100-1800). Negative margins were achieved in 14 patients. The two-year actuarial local control was 83% and estimated mean survival was 42.7 months (95% confidence interval 35.0-50.3 months). A positive or close margin was significant associated with poor local control but not overall survival. Results were comparable to open or endoscopic nasopharyngectomy. There was no 30 days post-operative mortality but one patient suffered from hypoxic brain damage after developing angioedema in the recovery room. Two patients developed permanent palatal fistulas and one patient had severe trismus after operation. Symptomatic osteoradionecrosis occurred in three patients. When comparing the quality of life assessment with patients after open maxillary swing nasopharyngectomy operation, robotic nasopharyngectomy patients have a higher score in social functioning scale and lower symptoms scores on pain, mouth opening and social eating. The global health score and other functioning scores were statistically not different. Robotic nasopharyngectomy is a feasible minimally invasive operation for resecting selected cases of locally recurrent NPC. The operation is associated with minor long-term complications and better quality of life. Early oncological results in are also encouraging. With rapid development of medical robotic technologies, further research in the field should be continued. / published_or_final_version / Surgery / Master / Master of Surgery

published_or_final_version / Clinical Oncology / Doctoral / Doctor of Philosophy