published_or_final_version / Medicine / Master / Doctor of Medicine

Abstract not available. / Pak Wai Martin. / Adviser: Charles Andrew van Hasselt. / Source: Dissertation Abstracts International, Volume: 72-10, Section: B, page: . / Thesis (M.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 245-269). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.

Nasopharyngeal carcinoma (NPC) is closely associated with Epstein-Barr Virus (EBV).Early diagnosis of NPC will improve the overall survival. However, traditional EBV markers do not perform well in high-risk individuals or for early detection of NPC. Aberrant promoter hypermethylation of tumor suppressor genes (TSGs) is an important epigenetic change in early tumorigenesis. This study identified a promising panel of methylation markers for early detection of NPC and assessed the clinical usefulness of these markers using nasopharyngeal (NP) brushing and blood specimens. Methylation-sensitive high resolution melting (MS-HRM) assays were carried out to assess the methylation status of a selected panel of four TSGs (RASSF1A, WIF1, DAPK1, RAR2)in biopsies, NP brushings and cell-free plasma from NPC patients. NP brushing and blood samples from high-risk and cancer-free groups were used as controls. The DNA methylation panel showed higher sensitivity and specificity than the EBV DNA markerincell-free plasma for early stage (Iand II) NPC (sensitivity: 64.6% vs. 51.2% and specificity: 96.0% vs. 88.0%, respectively). In combination with plasma EBV DNA, testing for DNA methylation in plasma and NP brushings using the four-gene MS-HRM test significantly increased the detection rate for all stages of NPC(94.1% for stages I-II, 98.4% for stages III-IV) as well as recurrence(93.5%). Aberrant activation of the Wnt signaling pathway is a common mechanism for cell transformation and tumor development in a variety of human cancers. A high frequency of promoter hypermethylation of WIF1was observed in NPC cell lines (100%), primary tumor biopsies(89.7%), NP brushings (80.2%), and cell-free plasma (51.8%),with no significant correlation with NPC stage. Simultaneously, expression of WIF1 was completely silenced in NPC cell lines (HONE1, HK1, HNE1, SUNE1, CNE1, CNE2, and C666),but not in immortalized NP epithelial cells (NP460 and NP69). These together suggested an important role of WIF1 in NPC development. In vitro and in vivo functional assays revealed a tumor suppressive role of WIF1in NPC. Restoration of WIF1expression in NPC cells significantly suppressed anchorage-independent growth, in vivo tumorigenicity, invasion, migration, and angiogenesis of NPC cells. A number of important angiogenesis-related genes were down-regulated by WIF1expression, including IL6,IL8,VEGF165,VEGFA, PDGFB, and MCP1. There is inhibition of the Wnt/β-catenin signaling pathway, manifested as decreased β-catenin expression and TCF/LEF Wnt promoter activity. These data indicated the important regulatory role of Wnt signaling pathway in NPC tumorigenicity, invasion, migration, and angiogenesis, by interacting with the complex signaling network in NPC cells. To conclude, the MS-HRM assay on the selected gene panel in combination with the EBV DNA test, increases the sensitivity for NPC detection at an early stage and detection of recurrence and has great potential to become a non-invasive test for early diagnosis and disease monitoring after treatment. Collectively, results from this study reveal that WIF1is not only a sensitive biomarker, but also a tumor suppressor gene in NPC. Understanding the molecular regulatory role ofWIF1in NPC will facilitate the diagnosis of NPC, and development of novel NPC therapeutic strategy. / published_or_final_version / Clinical Oncology / Doctoral / Doctor of Philosophy

1. Study on improving the diagnostic accuracy of treatment-naive nasopharyngeal carcinoma. / 2. Study on diagnostic accuracy of EBV-DNA on recurrent nasopharyngeal carcinoma. / 3. Studies on EBV-DNA as a screening tool for nasopharyngeal carcinoma. Part 1. To define the detection rate of NPC and the false-positive rate of IgA-VCA in an IgA-VCA-based screening problem, and to define the specificity of IgA-EA in IgA-VCA-positive screenees. Part 2. To define the specificity of EBV-DNA in IgA-VCA-positive screenees. Part 3. To define the sensitivity of IgA-EA, and EBV-DNA in IgA-positive NPC patients. / 4. Studies on pre-therapy prognostication of nasopharyngeal carcinoma Study Part 1. Objective. To assess the role of EBV-DNA in pre-therapy prognostication of early-stage NPC. / Background. The specific association between nasopharyngeal carcinoma (NPC) and the Epstein-Barr virus (EBV) had been exploited to develop a spectrum of EBV-antibodies-based blood markers. Among these markers, the Immunoglobulin A antibody against the viral capsid antigen (IgA-VCA) of the EBV has been the most popularly employed marker to assist diagnosis of NPC. There is however a relative paucity of data on the application of blood markers for screening, for detection of relapse, and for prognostification of patient cohorts managed in present-day therapy oncology protocols. Peripheral blood EBV-DNA, measured by quantitative polymerase chain reaction assay, is a newly-developed marker, and represents a prototype model of a nuclei acid-based, as opposed to antibody-based, EBV tumor marker for NPC. The present thesis describes the translation of this basic scientific advance into clinical applications, through several prospective and retrospective studies that address the diagnosis of treatment-naive NPC, the detection of recurrent NPC, the screening of individuals at risk of NPC, the pre-therapy prognostication for NPC to guide for choice of therapy. The role of integration of conventional markers and EBV-DNA in clinical applications was also examined. / Study Part 2. Objectives. To assess whether incorporation of EBV-DNA data to TNM staging improves prognostic discrimination of patients subsets within individual cancer stage, to assess if EBV-DNA is an independent prognostic factor for survival after ontological therapy. (Abstract shortened by UMI.) / Leung Sing-fai. / "February 2005." / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3695. / Thesis (M.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / School code: 1307.

(1) MRI is shown to be an accurate test for detecting NPC and one which has the potential to be used in screening to (a) screen out normal patients who do not require endoscopie biopsy; and (b) identify small tumours that would be missed on endoscopy. / (2) At diagnosis staging NPC by MRI reveals that oropharyngeal and maxillary sinus invasion are markers of more advanced disease than reflected in current staging system. Tumour involvement of the preclival/prevertebral region, skull base and retropharyngeal nodes are more common than previously recognised by computed tomography, while parapharyngeal tumour invasion is less common. The latter resuits from the superior ability of MRI to differentiate primary tumours with true parapharyngeal invasion from those contained within the nasopharynx which are causing bowing of the wall or lie adjacent to a retropharyngeal node. / (3) Post treatment complications were detected by MRI in over 50% of patients. Neural damage, especially to the temporal lobes and 12th cranial nerves, was the most frequent complication (48%), followed by osteoradionecrosis (20%) involving the mandible, upper cervical spine and skull base, the latter including destruction of the roof of the nasopharynx. Malignant tumours and unusual benign masses (6%) showed radiological features useful in the differential diagnosis from NPC recurrence. Malignant tumours were mainly squamous cell carcinomas or sarcomas showing a predilection for the maxillary region, tongue and external auditory canal. The unusual benign masses were found in the nasopharynx/sphenoid sinus. / (4) Finally functional MRI using DWI and 1H-MRS are feasible in the technically challenging region of the head and neck. Choline ratios and ADC values of NPC are established. The successful demonstration of differences between the biomarkers of NPC and those of lymphoma and squamous cell carcinoma, show that functional MRI is a new tool for the evaluation of NPC, opening up the possibility that these biomarkers can be used for monitoring NPC treatment response in the future. / Magnetic resonance imaging (MRI) provides excellent anatomical detail and functional information about cancer. This thesis explores the role of MRI in the assessment of nasopharyngeal carcinoma (NPC) from detection through to the long term complications of radiotherapy treatment. / Ann D King. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3468. / Thesis (M.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 180-191). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English only. / School code: 1307.

Nasopharyngeal Carcinoma (NPC) as a typical malignancy that occurs in high-incidence areas, e.g. southern China region, including Hong Kong, and it has aroused wide interests for local researchers to study. The Epstein-Barr virus (EBV) was reported as a vital herpes virus for the growth of NPC. Two significant proteins in EBV, namely Epstein-Barr Nuclear Antigen 1 (EBNA1) and latent infection membrane protein 1 (LMP1) are crucial for virus maintenance and EBV-infected cell development, and essential for cell proliferation and differentiation of EBV latent life cycle, respectively. Thus, inhibition of EBNA1 and LMP1 can be regarded as effective and potent therapy on EBV-associated cancers. In this thesis, the conjugation of core-shell structured upconversion nanoparticles (UCNPs) with distinct EBV-specific peptides including EBNA1 and LMP1 targeting peptides to achieve both impressive inhibition on EBV-positive cancers in vitro/in vivo and visualization on EBV-positive cells with responsive upconversion emission signals were investigated. Taking advantage of lanthanide-based UCNPs, their unique photophysical properties offer deep tissue penetration depth, negligible photobleaching and photocytotoxicity, and therefore provides a solid foundation for convincible theranostic studies. Furthermore, desired inhibitory performance was achieved, it was shown that ~50 mg/mL of nanoprobes can inhibit half of EBV-infected cell viability and only 0.25 mg/tumor of nanoprobes dosage via intravenous injection can prohibit 64.7% of growth inhibition of an EBV-positive tumor