鼻咽癌(nasopharyngeal carcinoma, NPC)與艾巴氏病毒(Epstein-Barr virus, EBV)和遺傳及表現遺傳變異有連串關係。儘管鼻咽癌腫瘤的發生機制仍然未知,最近研究顯示微核糖核酸(microRNA, miRNA)通過調節細胞增殖凋亡遷移和侵襲等方式對鼻咽癌的生成起著至關重要的作用。為了確定微核糖核酸與鼻咽癌發生的相關機制及其扮演的角色，我們集中研究微核糖核酸在鼻咽癌腫瘤中所發生的變異，探討這些異常表達的微核糖核酸的功能，並揭開與幹細胞相關的微核糖核酸在鼻咽癌幹細胞樣細胞(cancer stem-like cell, CSC)裏所扮演的角色。 / 通過使用微陣列技術(Agilent Microarray)， 我們運用了 866個人類與 89個病毒微核糖核酸探針,以識別出多個帶有艾巴氏病毒的鼻咽癌腫瘤細胞系裏的微核糖核酸表達圖譜。相比正常的鼻咽上皮細胞系NP69，113個微核糖核酸在鼻咽癌中的差異表達已被鑒定出來。其中58個在鼻咽癌裏下調的微核糖核酸表達，miR-31的轉錄下調現象在鼻咽癌腫瘤細胞系和原發腫瘤中被不斷地發現。在7個帶有艾巴氏病毒的腫瘤細胞系樣本裏, 其中6個(86%)樣本呈miR-31下調跡象。與此同時，以顯微切割技術所得的38個原發腫瘤樣本中全部(100%)都顯示有miR-31下調的跡象。相比之下，所有正常的鼻咽上皮細胞都顯出高表達的miR-31。 / miR-31位於染色體9p21.3上，距離CDKN2A (p16) 0.5Mb處。這是在鼻咽癌細胞裏通常缺失的位置。在X1915和X99186腫瘤細胞系中，已證實在miR-31和CDKN2A位點上都出現了純合性缺失。在四株不具備miR-31缺失的腫瘤細胞系裏，甲基化特異性聚合酶連鎖反應 (methylation-specific PCR, MSP) 和亞硫酸氫鈉測序法(bisulfite sequencing)發現了高甲基化的CpG島。使用5-aza-2’-deoxycytidine (5-Aza-dC) 治療後，鼻咽癌細胞株C666-1被證實恢復了miR-31轉錄。這些結果表明，純合性缺失和啟動子高甲基化是造成miR-31在鼻咽癌裏轉錄失效的主要發生機制。 / 微陣列技術和生物信息學分析找出了一些可能受miR-31影響的基因。其中FIH1和MCM2被確定為在鼻咽癌細胞裏受miR-31影響的基因。我們證實miR-31與FIH1和MCM2 信使核糖核酸的3’UTR處結合會抑制螢光素酶的活性。在鼻咽癌細胞裏miR-31的異位表達也會壓抑FIH1和MCM2蛋白的表達。更重要的是，恢復正常的miR-31表達或敲除FIH1表達能顯著地抑制C666-1細胞的增殖和移動能力。C666-1細胞的克隆形成能力和錨定依賴性生長都顯著地被miR-31的表達所抑制。穩定的miR-31表達亦能抑制鼻咽癌腫瘤在裸鼠體內的生長。此外，FIH1的敲除加強了p21和磷酸化p53 (Ser15) 的表達。這些結果暗示了miR-31是一個與鼻咽癌至關重要的微核糖核酸。 它通過了對FIH1的壓制，負面地調節細胞的增殖和移動。 / 使用微核糖核酸微陣列分析後，我們在鼻咽癌細胞中培養的懸浮細胞球裏篩選出差異表達的微核糖核酸。同樣地，實時螢光定量逆轉錄聚合酶鏈反應(qRT-PCR) 亦證實了miR-96和miR-183在C666-1懸浮細胞球裏是被抑制的。此外，miR-96和miR-183的異位表達顯著地降低了C666-1懸浮細胞球形成和克隆形成的能力。這項研究結果暗示, miR-96和miR-183的抑制對鼻咽癌幹細胞樣細胞的形成非常重要。 / 總的來說，某些微核糖核酸已被確定為潛在的鼻咽癌腫瘤抑制基因。 在帶艾巴氏病毒的鼻咽癌裏，miR-31的表達被證實是因純合性缺失和啟動子高甲基化而被下調的。miR-31抑制鼻咽癌細胞的增殖錨定依賴性生長細胞遷移和體內腫瘤的生長。同時，miR-96和miR-183也被發現對維持鼻咽癌的幹細胞樣特性起著一定作用。這些結果表明微核糖核酸對鼻咽癌腫瘤的生成扮演著抑制的角色。對微核糖核酸的機制作進一步全面了解將改進鼻咽癌的治療策略。 / Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC) has been reported to be related to a number of genetic and epigenetic changes, however, the molecular mechanism leading to NPC tumorigenesis still remains unclear. Recently, microRNAs (miRNAs) have been demonstrated to play vital roles in NPC development via regulating cell proliferation, apoptosis, and cell migration and invasion. In this study, we aim to elucidate the role of miRNAs in NPC tumorigenesis in this study by identifying the miRNA aberration, investigating the possible functions of these aberrantly expressed miRNAs, and unraveling the role of stemness-related miRNAs in NPC cancer stem-like cells (CSCs). / By using Agilent Microarray with 866 human and 89 viral miRNA probes, miRNA expression profiles of multiple EBV-associated NPC tumor lines were generated. Compared to NP69, a nonmalignant nasopharyngeal epithelial cell line, 113 differentially expressed miRNAs were identified. Among the 58 down-regulated miRNAs in NPC, transcriptional silencing of miR-31 was consistently found in both NPC tumor lines and primary tumors. Down-regulation of miR-31 was detected in 6 of 7 (86%) EBV-positive tumor lines and 38 of 38 (100%) microdissected primary tumors, while all normal nasopharyngeal epithelia showed high expression of miR-31. / miR-31 is located at 0.5 Mb telomeric to CDKN2A (p16) on chromosome 9p21.3, which is commonly deleted in NPC. Homozygous deletion of both miR-31 and CDKN2A loci was confirmed in tumor lines X1915 and X99186. In the four tumor lines with intact miR-31, hypermethylation of 5’ CpG islands was detected by methylation-specific PCR (MSP) and bisulfite sequencing analysis. Restoration of miR-31 transcription was demonstrated in the EBV-positive NPC cell line C666-1 treated with 5-aza-2’-deoxycytidine. These findings suggested that homozygous deletion and promoter hypermethylation are the major mechanisms for transcriptional silencing of miR-31 in NPC. / By microarray and bioinformatic analysis, a number of putative targets of miR-31 were identified. Among these candidates, FIH1 and MCM2 were found to be the targets of miR-31 in NPC. We have shown that binding of miR-31 on FIH1 and MCM2 mRNA 3’UTR suppressed their luciferase activity. Ectopic expression of miR-31 in NPC cells resulted in repression of FIH1 and MCM2 protein expression. Importantly, the restoration of miR-31 or knockdown of FIH1 expression significantly suppressed proliferation as well as migration of C666-1 cells. Clone-forming ability and anchorage-independent growth of C666-1 were significantly inhibited by miR-31 expression. Stably expressed miR-31 was also demonstrated to inhibit NPC tumor growth in nude mice. Furthermore, expression of p21 and phospho-p53 (Ser15) was found to be increased by FIH1 knockdown. These results implied that miR-31 is a critical NPC-associated miRNA which negatively regulates cell proliferation and migration via FIH1 repression. / By miRNA microarray analysis, we have screened for differentially expressed miRNAs in sphere-forming cells of EBV-associated NPC. In concordance with microarray findings, suppression of miR-96 and miR-183 in C666-1 spheroids was confirmed by qRT-PCR. Ectopic expression of miR-96 and miR-183 significantly reduced the sphere-forming and clone-forming ability of C666-1 cells. The findings implied that miR-96 and miR-183 repression is important in the formation of NPC CSCs. / In summary, several miRNAs were identified as potential tumor suppressor genes in NPC. miR-31 was found down-regulated by homozygous deletion or promoter hypermethylation in EBV-associated NPC. It plays roles in NPC pathogenesis by suppressing NPC cell proliferation, clone-forming ability, cell anchorage-independent growth, migration and in vivo tumor growth. Moreover, miR-96 and miR-183 were found to have a role in the maintenance of NPC stem-like properties. These findings suggested important tumor suppressive roles of miRNAs in regulating NPC tumorigenesis, and a better understanding on the miRNA mechanisms may potentiate better therapeutic strategies for NPC. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Cheung, Ching Mei. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 177-209). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / Abstract --- p.i / 摘要 --- p.iv / Thesis / Assessment Committee --- p.vii / Acknowledgements --- p.viii / Table of contents --- p.ix / List of figures --- p.xv / List of tables --- p.xviii / List of publications --- p.xix / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Nasopharyngeal carcinoma (NPC) --- p.1 / Chapter 1.1.1 --- Histopathology and epidemiology --- p.1 / Chapter 1.1.2 --- Etiology --- p.2 / Chapter 1.1.2.1 --- Environmental factors --- p.2 / Chapter 1.1.2.2 --- Genetic factors --- p.3 / Chapter 1.1.2.3 --- Epstein-Barr virus (EBV) infection --- p.3 / Chapter 1.2 --- Molecular pathogenesis of NPC --- p.5 / Chapter 1.2.1 --- Cytogenetic changes --- p.5 / Chapter 1.2.2 --- NPC-associated tumor suppressor genes (TSGs) --- p.6 / Chapter 1.2.3 --- NPC-associated oncogenes --- p.8 / Chapter 1.3 --- MicroRNAs --- p.10 / Chapter 1.3.1 --- Biogenesis of microRNAs --- p.10 / Chapter 1.3.2 --- MicroRNAs and cancers --- p.15 / Chapter 1.3.2.1 --- MicroRNAs - tumor suppressors --- p.15 / Chapter 1.3.2.2 --- MicroRNAs - oncogenes --- p.16 / Chapter 1.4 --- MicroRNAs in nasopharyngeal carcinoma --- p.18 / Chapter 1.4.1 --- MicroRNA profiling in NPC --- p.18 / Chapter 1.4.2 --- OncomiRs in NPC --- p.20 / Chapter 1.4.3 --- Tumor suppressor miRNAs in NPC --- p.22 / Chapter 1.4.4 --- miRNAs and cancer stem-like cells (CSCs) --- p.27 / Chapter 1.4.5 --- Clinical implication of miRNAs in NPC --- p.29 / Chapter 1.5 --- Aims of study --- p.32 / Chapter Chapter 2 --- Materials and methods --- p.34 / Chapter 2.1 --- Patient biopsies --- p.34 / Chapter 2.2 --- NPC cell lines and xenografts --- p.34 / Chapter 2.2.1 --- Cell lines --- p.34 / Chapter 2.2.2 --- Xenografts --- p.36 / Chapter 2.3 --- Total RNA Isolation --- p.39 / Chapter 2.4 --- DNA extraction --- p.39 / Chapter 2.5 --- Protein Extraction --- p.40 / Chapter 2.6 --- Western Blotting --- p.40 / Chapter 2.7 --- Microarray analysis --- p.43 / Chapter 2.7.1 --- MicroRNA microarray --- p.43 / Chapter 2.7.2 --- Gene expression microarray --- p.44 / Chapter 2.8 --- Quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR) --- p.45 / Chapter 2.8.1 --- Conventional qRT-PCR --- p.45 / Chapter 2.8.2 --- Stem-looped qRT-PCR --- p.46 / Chapter 2.9 --- Preparation of stable clone of miR-31 --- p.51 / Chapter 2.9.1 --- Cloning and plasmid DNA preparation --- p.51 / Chapter 2.9.1.1 --- Bacterial Transformation --- p.51 / Chapter 2.9.1.2 --- Plasmid DNA Extraction --- p.51 / Chapter 2.9.2 --- DNA Sequencing --- p.52 / Chapter 2.9.3 --- Stable transfection --- p.52 / Chapter 2.9.4 --- Clone selection --- p.53 / Chapter 2.10 --- Transient transfection --- p.55 / Chapter 2.11 --- Flow cytometry --- p.55 / Chapter 2.11.1 --- Apoptosis analysis by Annexin V --- p.55 / Chapter 2.11.2 --- Cell cycle analysis by propidium iodide (PI) --- p.56 / Chapter 2.11.3 --- Detection of stem-like cell markers --- p.56 / Chapter 2.12 --- Cell proliferation analysis --- p.56 / Chapter 2.12.1 --- WST-1 assay --- p.56 / Chapter 2.12.2 --- BrdU assay --- p.57 / Chapter 2.13 --- Anchorage-independent growth assay --- p.58 / Chapter 2.14 --- Clone formation assay --- p.58 / Chapter 2.15 --- Cell migration assay --- p.54 / Chapter 2.16 --- In vivo tumorigenicity --- p.59 / Chapter 2.17 --- Dual luciferase reporter assay --- p.60 / Chapter 2.17.1 --- Luciferase reporter vectors --- p.60 / Chapter 2.17.2 --- Luciferase reporter assay --- p.60 / Chapter 2.18 --- Mapping homozygous deletion and genes in chromosome 9p21.3 --- p.64 / Chapter 2.19 --- 5-aza-2’-deoxycytidine (5-Aza-dC) and Trichostatin A (TSA) treatments --- p.64 / Chapter 2.20 --- Methylation specific-PCR (MSP) and bisulfite sequencing analysis --- p.68 / Chapter 2.20.1 --- Bisulfite modification --- p.68 / Chapter 2.20.2 --- Methylation specific-PCR (MSP) --- p.69 / Chapter 2.20.3 --- Bisulfite sequencing analysis --- p.69 / Chapter 2.21 --- Statistical analysis --- p.70 / Chapter 2.22 --- In situ hybridization (ISH) analysis --- p.73 / Chapter Chapter 3 --- Identification of novel deregulated microRNAs in nasopharyngeal carcinoma --- p.74 / Chapter 3.1 --- Introduction --- p.74 / Chapter 3.2 --- Results --- p.80 / Chapter 3.2.1 --- Aberrant expression of microRNAs in NPC --- p.80 / Chapter 3.2.2 --- Homozygous deletion of miR-31 in NPC --- p.90 / Chapter 3.2.3 --- Hypermethylation of 5’ CpG islands of miR-31 in NPC --- p.92 / Chapter 3.2.4 --- Detection of miR-31 expression in normal epithelia and NPC by in situ hybridization --- p.99 / Chapter 3.3 --- Discussion --- p.101 / Chapter Chapter 4 --- Characteristics of miR-31 and its targets in NPC --- p.105 / Chapter 4.1 --- Introduction --- p.105 / Chapter 4.2 --- Results --- p.107 / Chapter 4.2.1 --- Effects of exogenous miR-31 on NPC cells --- p.107 / Chapter 4.2.1.1 --- miR-31 effect on C666-1 cell proliferation and cell cycle progression --- p.107 / Chapter 4.2.1.2 --- Clone-forming ability and anchorage-independent growth of C666-1 --- p.113 / Chapter 4.2.1.3 --- Migration ability of C666-1 --- p.113 / Chapter 4.2.2 --- Effects of stably expressed miR-31 on NPC cells --- p.117 / Chapter 4.2.2.1 --- Stable clones selection by restoring precursor of miR-31 into C666-1 --- p.117 / Chapter 4.2.2.2 --- Cell proliferation and cell cycle progression in stable clones of miR-31 --- p.117 / Chapter 4.2.2.3 --- Anchorage-independent growth of C666-1 stable clones --- p.117 / Chapter 4.2.2.4 --- Tumorigenicity of C666-1 stable clones expressing miR-31 in vivo --- p.118 / Chapter 4.2.3 --- Identification of miR-31 targets in NPC cells --- p.125 / Chapter 4.2.3.1 --- miR-31 targets FIH1 and MCM2 --- p.125 / Chapter 4.2.3.2 --- Other reported targets of miR-31 in NPC --- p.131 / Chapter 4.2.4 --- Functional analysis of FIH1 in NPC cells --- p.133 / Chapter 4.2.4.1 --- Repression of FIH1 by siRNAs --- p.133 / Chapter 4.2.4.2 --- Proliferation of C666-1 with FIH1 knockdown --- p.133 / Chapter 4.2.4.3 --- Clone-forming and migration ability of C666-1 transfected with siFIH1 --- p.133 / Chapter 4.2.4.4 --- Putative downstream targets of FIH1 --- p.139 / Chapter 4.2.5 --- Identification of novel miR-31 targets by gene expression microarray --- p.139 / Chapter 4.3 --- Discussion --- p.145 / Chapter Chapter 5 --- MicroRNAs regulation on NPC stem-like properties --- p.154 / Chapter 5.1 --- Introduction --- p.154 / Chapter 5.2 --- Results --- p.156 / Chapter 5.2.1 --- MicroRNA expression profiles in NPC sphere-forming cells --- p.155 / Chapter 5.2.2 --- Ectopic expression of miR-183 family and miR-203 in NPC --- p.161 / Chapter 5.2.2.1 --- Sphere-forming ability of NPC cells --- p.161 / Chapter 5.2.2.2 --- Clone-forming ability of C666-1 --- p.161 / Chapter 5.2.3 --- Sphere-forming ability of NPC cells transfected with anti-miR-96 and anti-miR-183 --- p.164 / Chapter 5.2.4 --- Expression of cacner stem cell markers in NPC cells transfected with miR-96 and miR-183 --- p.164 / Chapter 5.3 --- Discussion --- p.167 / Chapter Chapter 6 --- General discussion --- p.170 / Reference --- p.177

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.

Celecoxib is a COX-2 selective non-steroidal anti-inflammatory drug which has been shown to inhibit growth and induce apoptosis in various cancer cell lines. Using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and an apoptosis detection kit, we demonstrated that celecoxib was able to induce growth inhibition and apoptosis in a dose-dependent manner in 3 NPC cell lines: HK-1, Hone-1, and C666-1. Afterwards, a proteomic approach was used to study the underlying mechanisms involved in celecoxib-mediated effects on two COX-2 positive NPC cell lines (HK-1 and C666-1). Results showed that a total of 18 protein spots were differentially expressed in the HK-1 and C666-1 cells. On the other hand, we also compared the proteomic expression profile between an NPC cell line (C666-1) and a normal nasopharynx cell line (NP69) in order to study whether those differentially expressed proteins after celecoxib treatment were also involved in NPC carcinogenesis. Proteomics results with confirmation using Western blotting discovered that HSP27 phosphorylated of serine 82 (HSP27-pSer82) protein was up-regulated in C666-1 cells when compared with that in NP69 cells. After treatment with celecoxib, expression of HSP27-pSer82 protein was down-regulated in both HK-1 and C666-1 cells. These findings suggest that down-regulation of HSP27-pSer82 protein expression may have mediated the growth-inhibitory effects of celecoxib in HK-1 and C666-1 cells. Finally, other differential expressed proteins identified from proteomics with confirmation by immunocytochemical staining in the 2 NPC cell lines and 40 NPC patient specimens showed that down-regulation of annexin 2 and beta2-tubulin may be important in NPC formation. / COX-2 over-expression has been found in various cancers such as colorectal cancer, liver cancer and lung cancer. In vivo studies have shown that mice overexpressing COX-2 developed breast cancer whereas COX-2 knockout mice had reduced rates of cancer formation in the intestines and skin. In the present study, COX-2 expression in NPC patient biopsies was examined and correlated with the clinicopathological data of the patients. Immunocytochemical staining showed that COX-2 protein was over-expressed in 84.6% (66/78) of non-metastatic NPC patients and was associated with an advanced nodal stage (P<0.05). All these data support an important role for COX-2 in NPC pathogenesis. / In summary, this study is the first to identify HSP27-pSer82 protein as a potential target of celecoxib in NPC cells. Detailed investigations of the functional role of molecular targets identified in this study would improve our understanding of the chemotherapeutic effects of celecoxib and, in the long run, may lead to a more effective chemotherapeutic treatment to this common cancer. / Nasopharyngeal carcinoma (NPC) is prevalent in southern China. Although early stage patients have a high rate of cure with radiotherapy alone, the prognosis for those with stage III or IV disease remains poor due to subsequent development of distant metastases. Therefore there is an urgent need to develop novel biologic agents to improve treatment outcomes. / Chan, Ming Lok. / Adviser: Anthony T.C. Chan. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3418. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 141-171). / 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 and Chinese. / 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.

Advanced-stage nasopharyngeal carcinoma (NPC) presents very difficult scenarios for radiation therapy (RT) planning. The infiltration of tumor to the skull base and beyond means that the tumor is very close to critical normal organs (organs at risk, OARs). Despite the advent of intensity-modulated radiotherapy (IMRT) treatment technique---the state-of-art RT technique, conflicting requirements between organ protection and target dose conformity is still problematic. The objectives of the present research are (1) to investigate the dosimetry properties of IMRT treatment in advanced-stage NPC in respect of its dosimetric limitations and planning problems, (2) to develop new methods and tools to resolve such problems, in particular to improve the quality of treatment plans and efficiency of the dose planning and optimization process. A series of four inter-linked studies were conducted to address these issues. / In conclusion, the solutions to several major problems in IMRT planning for advanced-stage NPC were investigated and established. It has been demonstrated in this research that, by applying these methods and tools, significant improvement in the dosimetry and efficiency of IMRT treatment planning can be accomplished as compared with conventional IMRT planning techniques. It is expected that such would translate into an improvement in treatment throughput, better tumor control and reduction in normal tissues complications. The methods developed have potential to be applied to all stages of NPC and to other tumor sites. / The first study was to improve the efficacy in target coverage and organs sparing using an "organ-splitting" approach. The OARs which overlapped with targets were split into target-overlapping and non-overlapping segments and each segment was assigned with different constraints parameters to increase the degree of flexibility during optimization. As a result, a steep gradient in the dose distribution at the regions of interface between the targets and normal critical organs could be achieved and treatment quality was improved. In the second study, a thorough dosimetric comparison between conventional 2-dimensional (2D) RT and IMRT plans was conducted to determine, with reference to outcome of 2D treatments, the extended tolerance dose limits for the critical organs, especially that of the brainstem and spinal cord, and their planning organ at risk volume. Such data could then serve as reference in IMRT planning when the dose of critical organs need be exceeded in order to allow adequate dose to a very close by target. In the third study, the feasibility of using interpolated contours for segmentation of targets and OARs in IMRT planning was investigated. The result indicated that the use of interpolated contours in IMRT planning could significantly reduce the contouring time by about 50% without degrading the target coverage and OARS sparing. In the final study, an array of dose constraint templates that could accommodate different degrees of overlap between the targets and OARs, together with a template selection program, were developed to improve the efficiency of IMRT planning. By applying the methods and tools developed, IMRT treatment planning of advanced NPC could become more efficient and less dependent on planner's experience. / Chau, Ming Chun. / Adviser: Anthony Chan Tak Cheung. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 0948. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 118-128). / 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. / Abstract also in Chinese. / School code: 1307.

A comprehensive immunohistochemical study was carried out to investigate the phenotypes and prevalence of intraepithelial lymphocytes in NPC samples semi-quantitatively. CD25+/FOXP3+ T-cells were highly prevalent in primary NPCs, suggesting the presence of the immunosuppressive Tregs in tumor microenvironments. The low abundance of CD4+ T-cells, and the positive correlation between FOXP3 and CD8 staining in NPC samples imply that CD8+FOXP3+ Tregs may be present and play role in the suppression of anti-tumor immune response in NPC patients. The involvement of chemokine in the migration of tumor-infiltrating lymphocytes was studied. Chemokine ligand 20 (CCL20) was overexpressed in all EBV-positive NPC cell lines and xenografts compared to EBV-negative NPC, and immortalized normal nasopharynx epithelial cell lines. The presence of CCL20 was also found in primary tumors but not in normal epithelium. Furthermore, the ability of LMP1 to upregulate CCL20 expression in epithelial cells indicates that EBV may induce the production of chemokine involved in lymphocyte migration. / Epstein-Barr virus (EBV) is invariably associated with the development of nasopharyngeal carcinoma (NPC). Although the association of EBV and cancer has been reported for about four decades, it is still not clear how EBV latent infection contributes to the transformation of nasopharyngeal epithelial cells. The aims of this study are to identify EBV-regulated cellular genes and pathways and to determine the potential role of EBV in the modulation of anti-tumor immune responses in NPC. / In summary, EBV plays critical roles in the development of NPC by regulation of multiple cellular genes and pathways such as the Notch signaling cascade, and modulation of anti-tumor immune responses through the induction of chemokine important in migration of immune cells. / Notch signaling pathway functions in diverse cellular processes such as proliferation, apoptosis, adhesion, and epithelial to mesenchymal transition. In the current study, aberrant expression of activated Notch1 receptor (NICD), Notch ligand (Jagged1), negative regulator of Notch ( NUMB) and Notch downstream effector (HEY1) was detected in NPC cell lines and xenografts. Overexpression of NICD, Jagged1 and HEY1 proteins was also commonly found in primary tumors of NPC. / Transfection of Jagged1 to normal nasopharynx epithelial cells resulted in increased cell proliferation. Moreover, EBERs, which is abundantly expressed in EBV-positive NPC tumors, was capable of inducing the expression of Jagged1 in epithelial cells. The current data shows that Notch signaling pathway is aberrantly activated by the deregulated expression of multiple Notch components in NPC. The induction of Jagged1 by EBERs also implies the potential role of EBV in the activation of Notch signaling cascade in NPC. / Using high-density oligonucleotide microarray, expression profiles of EBV-infected NPC cell lines, HK1+EBV and HONE1+EBV, and their uninfected counterparts, HK1 and HONE, were generated. From the microarray results, six EBV-upregulated (JDP2, IL8, ATP6V0E2L, PLAP, PIK3C2B and AKR1B10 ) and three EBV-downregulated genes (BACE2, PADI3 and MMP1) were identified in both HK1 and HONE1 cells upon EBV latent infection. One hundred and thirty-eight and seventy-six genes were also found to be differentially modulated by EBV in HK1 and HONE1 cells, respectively. This study shows that cellular genes involved in wide range of biological processes and cellular functions are differentially regulated by EBV, which suggest that EBV modulates multiple pathways and processes during NPC tumorigenesis. / Hui, Wai Ying. / Adviser: Kw Lo. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 0806. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 166-204). / 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. / Abstract also in Chinese. / School code: 1307.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Pathology / Master / Master of Medical Sciences

Medical imaging informatics is one of the important research areas in radiology that studies how information available on medical images is retrieved, analyzed, and enhanced. Recent development in medical imaging informatics has resulted in improvement of diagnostic accuracy based on imaging examinations, as well as efficiency in clinical workflow. Computer aided diagnosis (CAD) and electronic patient record system (ePR) are both topics in medical imaging informatics that have matured from research concepts into commercially available computerized systems in clinical environment. The current challenges are to further broaden their scope of applications. In this thesis project, I developed a CAD system for interpreting PET/CT examinations and an ePR system for patient data integration in neurosurgery suites. Specifically, the CAD system in this project was designed to automatically diagnose nasopharyngeal carcinoma (NPC) on Positron emission tomography/computed tomography (PET/CT) examinations, which aimed to detect and classify both the primary NPC and its nodal metastasis. The regions of interests (ROIs) were segmented from the PET images and registered onto the CT in order to combine the imaging features from both modalities and the a priori anatomical knowledge of the suspicious lesion. These combined features were then classified by a support vector machine (SVM) to generate the final diagnosis result. The system was validated with 25 PET/CT examinations from 10 patients suffering from NPC, and the result produced by the system was compared to the gold standard of lesions manually contoured by experienced radiologists. The results confirmed that the system successfully distinguished all 53 genuine lesions from the mimickers due to normal physiological uptake and artifacts that also produced potentially confusing signals. The second part of the project involved development of an electronic patient record system (ePR) that integrated all the myriad of images and different types of clinical information before, during, and after neurosurgery operations, in order to enhance efficiency of work flow in this unique clinical environment. The system comprises of pre-, intra-, and post-operation modules which correspond to the different stages of the neurosurgery. The pre-op module was developed to store and categorize all images and data before the procedure to assist the surgeons in planning operation. The intra-op module integrates all the input signals, waveforms, images and videos that are produced by different imaging and physiological monitoring devices in the operation room during the surgery, and displays all the relevant information in a single large screen in real time to ease monitoring of the procedure. The post-op module helps surgeons to review all the data acquired from all the prior stages for follow-up of the treatment outcome. One-tumor case was utilized to test the pre-op module, and the signals and waveforms simulators were used to evaluate the performance of the intra-op module. In summary, two different medical informatics systems, a CAD and an ePR system were developed. Both showed promising results in laboratory tests. Future work would involve performance enhancement and feedback of the systems, and ultimately evaluation of these systems in the clinical environment. / published_or_final_version / Diagnostic Radiology / Master / Master of Philosophy