published_or_final_version / Biochemistry / Master / Master of Philosophy

神經母細胞瘤是一種交感神經系統的腫瘤。它是最常見的兒童顱外實體瘤。神經母細胞瘤約佔兒童腫瘤的8-10%，佔15%的兒童腫瘤死亡率。目前神經母細胞瘤的治療方法包括外科手術， 化學藥物治療， 放射治療， 幹細胞移植， 誘導分化治療和免疫治療。 然而，這些治療方法通常會導致許多無法避免的嚴重的副作用。因此，開發能高效抑制神經母細胞瘤但對正常細胞無明顯副作用的新型藥物顯得至關重要。最近，用來源於天然產物或中藥的化合物治療癌症引起了科學家的廣泛關注。靛玉紅-3’-肟（Indirubin-3’-oxime, I3M）和色胺酮（tryptanthrin）分別是從板藍根中分離得到的靛藍生物鹼和吲哚喹唑啉類生物鹼。據研究報導，這兩種生物鹼具有多種生物學和藥理學作用，包括抗菌，抗炎症和抗腫瘤作用。它們對體外的多種人腫瘤細胞具有抗腫瘤作用。然而，它們對人神經母細胞瘤的調節作用和作用機理仍不太清楚。在我的博士研究課題中，我們對板藍根生物鹼包括靛玉紅-3’-肟和色胺酮對人神經母細胞瘤的抗腫瘤活性和作用機制進行了研究和探討。 / 首先，我們研究了靛玉紅-3’-肟對人神經母細胞瘤的抗腫瘤活性和作用機制。實驗結果表明，靛玉紅-3’-肟能夠抑制人神經母細胞瘤LA-N-1, SH-SY5Y 和 SK-N-DZ細胞系的生長，並且其抑制效果呈時間和濃度依賴性。然而，靛玉紅-3’-肟對正常細胞無顯著的細胞毒性作用。對其生長抑制作用機制的研究結果表明靛玉紅-3’-肟能夠特異性地減少LA-N-1細胞系中線粒體的調節子ERR和 PGC-1的表達，從而導致線粒體生成減少，線粒體膜電位降低以及線粒體活性氧（ROS）增加。靛玉紅-3’-肟還增加週期蛋白依賴性蛋白激酶（CDK）抑制蛋白p27{U+1D37}{U+2071}{U+1D56}¹的蛋白水平並降低週期蛋白依賴性蛋白激酶2（CDK2）和細胞週期蛋白E（Cyclin E）的表達，從而導致細胞週期阻滯在G0/G1期。 另外，我們發現靛玉紅-3’-肟能減少SH-SY5Y細胞系的線粒體生成，增加細胞內活性氧的水準從而導致細胞週期停滯在G0/G1期和細胞凋亡。以上結果表明靛玉紅-3’-肟可能通過破壞線粒體的功能從而導致LA-N-1和SH-SY5Y細胞的細胞週期阻滯和誘導SH-SY5Y細胞的細胞凋亡來發揮其抗腫瘤的作用。 / 接著，我們對色胺酮對人神經母細胞瘤的抗腫瘤活性和作用機制進行了探討。我們研究的結果表明，色胺酮可以時間和濃度依賴性地抑制人神經母細胞瘤LA-N-1, SH-SY5Y 和 SK-N-DZ細胞系的生長，而對正常的細胞無顯著的細胞毒性。對色胺酮抑制人神經母細胞瘤生長的機制研究表明，色胺酮能顯著地降低細胞週期蛋白（Cyclin D1和 Cyclin D3）和週期蛋白依賴性蛋白激酶（CDK4和CDK6）的蛋白水平從而導致細胞週期停滯在G0/G1期。色胺酮可以激活半胱氨酸天冬氨酸蛋白酶8,9和3/7（caspase 8, caspase 9 和 caspase 3/7）從而誘導LA-N-1細胞凋亡。色胺酮還可以誘導LA-N-1細胞分化，表現為神經細胞分化的細胞形態，乙醯膽鹼酯酶活性的增加和多種細胞分化的分子標記的表達上調。另外，色胺酮還能降低LA-N-1細胞中N-myc的表達。有趣的是，通過RNA干擾技術降低N-myc的表達能誘導LA-N-1細胞的分化。總的來說，以上結果顯示色胺酮通過誘導細胞週期阻滯，細胞凋亡和細胞分化從而發揮其抗腫瘤的作用。它可能被開發為治療有N-myc基因擴增的高危的人神經母細胞瘤的潛在藥物。 / 此外，我們還研究了靛玉紅-3’-肟和色胺酮是否具有抗血管生成的作用。體外實驗的研究結果表明，靛玉紅-3’-肟和色胺酮能夠濃度依賴性地抑制人微血管上皮細胞 （HMEC-1細胞）的增殖，遷徙和血管生成，但對HMEC-1細胞卻沒有顯著的細胞毒性作用。此外，靛玉紅-3’-肟和色胺酮能顯著地抑制小鼠體內的基質膠栓（Matrigel plug）的血管生成。對它們抑制血管生成的機制的研究表明，靛玉紅-3’-肟能下調血管生成素1（Ang-1）和基質金屬蛋白酶2（MMP2）的表達，上調血管生成素2（Ang-2）的表達。靛玉紅-3’-肟能結合到血管內皮生長因數受體2（VEGFR2） 的ATP結合位點上從而抑制血管內皮生長因數受體2的磷酸化和下游的MEK/ERK和PI3K/AKT/GSK信號轉導通路。色胺酮同樣可以抑制多種血管生成因子（Ang-1,PDGFB 和MMP2）的表達。此外，它可以結合到血管內皮生長因數受體2 的ATP結合位點上從而抑制血管內皮生長因數受體2的磷酸化和血管內皮生長因數受體2介導的ERK1/2信號通路。以上的體外和體內實驗研究結果表明靛玉紅-3’-肟和色胺酮通過靶向血管內皮生長因數受體2介導的信號通路來發揮其抗血管生成的作用。它們可能被開發為治療血管生成相關疾病的潛在藥物。 / 總而言之，我們的研究結果表明靛玉紅-3’-肟和色胺酮通過誘導人神經母細胞瘤細胞的細胞週期阻滯，細胞凋亡或誘導神經細胞分化從而抑制人神經母細胞瘤細胞的生長。然而，它們對正常細胞無顯著的細胞毒性作用。此外，靛玉紅-3’-肟和色胺酮通過靶向血管內皮生長因數受體2介導的信號通路來發揮其抗血管生成的作用。未來的研究將進一步探討靛玉紅-3’-肟和色胺酮對人神經母細胞瘤細胞的分子作用機理。另外，通過人神經母細胞瘤細胞的裸鼠移植瘤動物模型可進一步去了解這些板藍根生物鹼在體內的抗腫瘤效果。 / Neuroblastoma, a tumor of the sympathetic nervous system, is the most common extracranial solid cancer in childhood. It accounts for 8% to 10% of all childhood cancers and for approximately 15% of cancer deaths in children. Current treatment modalities consist of surgery, chemotherapy, radiation therapy, stem cell transplantation, differentiation therapy and immunotherapy. However, these treatments often cause severe and inevitable side effects. It is important to develop novel drugs with higher efficacy on neuroblastoma cells and minimal side effects on normal cells. The use of new promising therapeutic compounds derived from natural products or Chinese herbs have attracted much attention of scientist as an alternative strategy in cancer treatment. Indirubin-3’-oxime (I3M) is an indigo alkaloid and tryptanthrin is an indoloquinazoline alkaloid which can be isolated from the dried roots of medicinal indigo plants known as Banlangen. These two alkaloids have been reported to possess various biological and pharmacological activities, such as anti-microbial, anti-inflammatory, and anti-tumor effects. They were found to exhibit potent anti-tumor activities on various types of human cancer cells in vitro. However, their modulatory effects on human neuroblastoma and the underlying mechanisms remain poorly understood. In my PhD project, the possible anti-tumor activities and action mechanisms of Banlangen alkaloids, including I3M and tryptanthrin, on human neuroblastoma cells were investigated. / Firstly, the anti-cancer effects of I3M on human neuroblastoma cells and the underlying mechanisms were investigated. I3M was found to inhibit the growth of the human neuroblastoma LA-N-1, SH-SY5Y and SK-N-DZ cells in a concentration- and time-dependent manner, but exhibited little, if any, direct cytotoxicity on normal cells. Mechanistic studies showed that I3M specifically decreased the expression of mitochondrial regulators ERRγ and PGC-1βand resulted in decreased mitochondrial mass and altered mitochondrial function characterized by reduction in mitochondrial membrane potential and elevation of reactive oxygen species (ROS) level in LA-N-1 cells. I3M also increased the level of cyclin-dependent kinase (CDK) inhibitor p27{U+1D37}{U+2071}{U+1D56}¹ and reduced the levels of CDK2 and cyclin E in LA-N-1 cells, leading to cell cycle arrest at the G0/G1 phase. In addition, I3M was also found to reduce the mitochondrial mass and increase the ROS level leading to cell cycle arrest at G0/G1 phase and apoptosis in SH-SY5Y cells. These results, when taken together, suggest that I3M might exert its anti-tumor activity by causing mitochondrial dysfunction which led to cell cycle arrest in LA-N-1 cells and resulted in cycle arrest and apoptosis in SH-SY5Y cells. / The anti-tumor effects and action mechanisms of tryptanthrin on the human neuroblastoma cells were also examined. Our results showed that tryptanthrin inhibited the growth of the human neuroblastoma LA-N-1, SH-SY5Y and SK-N-DZ cells in a concentration- and time-dependent manner, but exhibited little, if any, direct cytotoxicity on normal cells. Mechanistic studies indicated that tryptanthrin significantly reduced the protein levels of cyclin D1, cyclin D3, CDK4 and CDK6 leading to cell cycle arrest at G0/G1 phase. In addition, tryptanthrin activated caspase 8, caspase 9 and caspase 3/7 resulting in apoptosis of the human neuroblastoma LA-N-1 cells. Moreover, tryptanthrin induced neuronal differentiation of LA-N-1 cells, as assessed by morphological criteria, enhancement of acetylcholine esterase activity and up-regulation of various differentiation markers. Tryptanthrin treatment also led to the significant reduction of N-myc expression in LA-N-1 cells. Interestingly, down-regulating N-myc expression using siRNA induced neuronal differentiation of LA-N-1 cells. Collectively, these results indicate that tryptanthrin might exert its anti-tumor activity on the human neuroblastoma LA-N-1 cells by inducing cell cycle arrest, apoptosis and neuronal differentiation. It might be exploited as a potential therapeutic candidate for the treatment of high-risk neuroblastomas with N-myc-amplification. / Moreover, the anti-angiogenic activities of I3M and tryptanthrin were studied. Our results showed that I3M and tryptanthrin inhibited the proliferation, migration, and tube formation of the human microvascular endothelial HMEC-1 cells in vitro in a concentration-dependent manner but exhibited no significant cytotoxicity on these cells. Moreover, I3M and tryptanthrin markedly suppressed the in vivo angiogenesis in Matrigel plugs in mice. Mechanistic studies indicated that I3M down-regulated the expression of Ang-1 and MMP2 and up-regulated the expression of Ang-2. It also bound to the ATP-binding site of VEGFR2 and inhibited the phosphorylation of VEGFR2 leading to suppression of the down-stream MEK/ERK and PI3K/AKT/GSK signaling pathways in HMEC-1 cells. Similarly, tryptanthrin also reduced the expression of several angiogenic factors (Ang-1, PDGFB and MMP2) in HMEC-1 cells. In addition, tryptanthrin also bound to the ATP-binding site of VEGFR2 and suppressed the phosphorylation of VEGFR2 and VEGFR2-mediated ERK1/2 signaling pathway in HMEC-1 cells. Collectively, our results demonstrated that I3M and tryptanthrin exhibited anti-angiogenic activity both in vitro and in vivo by specifically targeting the VEGFR2-mediated signaling pathways and might be exploited as potential therapeutic candidates for the treatment of angiogenesis-related diseases. / In conclusion, our findings indicate that I3M and tryptanthrin might exert their growth-inhibitory effect on the human neuroblastoma cells by causing cell cycle arrest, inducing apoptosis or inducing neuronal differentiation. However, they exhibited minimal cytotoxicity towards the normal cells. Moreover, I3M and tryptanthrin were found to possess anti-angiogenic activities by targeting the VEGFR2-mediated signaling pathways. In the future, investigations should be focused on further elucidation of the molecular action mechanisms of I3M and tryptanthrin on human neuroblastoma cells and to test the anti-tumor efficacy of I3M and tryptanthrin in animal models, using human neuroblastoma xenografts in nude mice. / 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. / Liao, Xuemei. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 206-229). / Abstract also in Chinese. / Acknowledgments --- p.i / Abbreviations --- p.ii / Publications --- p.vi / Abstract --- p.vii / 摘要 --- p.xii / Table of Contents --- p.xvi / Chapter One / General Introduction --- p.1 / Chapter 1.1 --- Neuroblastoma --- p.2 / Chapter 1.1.1 --- Epidemiology of neuroblastoma --- p.2 / Chapter 1.1.2 --- Classification of neuroblastoma --- p.6 / Chapter 1.1.3 --- Clinical symptoms and diagnosis of neuroblastoma --- p.10 / Chapter 1.1.4 --- Molecular pathogenesis of neuroblastoma --- p.13 / Chapter 1.1.4.1 --- Genetic alterations in neuroblastoma --- p.13 / Chapter 1.1.4.2 --- Disruption of cell division cycle, apoptotic and signaling pathways --- p.16 / Chapter 1.1.5 --- Treatment strategies --- p.19 / Chapter 1.1.5.1 --- Low-risk neuroblastoma treatment strategy --- p.19 / Chapter 1.1.5.2 --- Intermediate-risk neuroblastoma treatment strategy --- p.20 / Chapter 1.1.5.3 --- High-risk neuroblastoma treatment strategy --- p.21 / Chapter 1.1.5.4 --- Side effects of treatment --- p.23 / Chapter 1.2 --- Banlangen alkaloids --- p.23 / Chapter 1.2.1 --- Overview of Banlangen alkaloids --- p.23 / Chapter 1.2.2 --- Biological and pharmacological effects of Banlangen alkaloids --- p.28 / Chapter 1.2.2.1 --- Anti-inflammatory activity --- p.28 / Chapter 1.2.2.2 --- Anti-microbial activity --- p.29 / Chapter 1.2.2.3 --- Anti-tumor activity --- p.30 / Chapter 1.2.2.4 --- Other biological activities --- p.32 / Chapter 1.2.3 --- Bioavailability of Banlangen alkaloids --- p.33 / Chapter 1.2.4 --- Toxicity of Banlangen alkaloids --- p.34 / Chapter 1.3 --- Aims and scope of this project --- p.36 / Chapter Two / Materials and Methods --- p.38 / Chapter 2.1 --- Materials --- p.39 / Chapter 2.1.1 --- Animals --- p.39 / Chapter 2.1.2 --- Cell lines --- p.39 / Chapter 2.1.3 --- Cell culture media --- p.41 / Chapter 2.1.4 --- Drugs and chemicals --- p.42 / Chapter 2.1.5 --- Reagents and buffers for cell culture --- p.44 / Chapter 2.1.6 --- General staining solutions --- p.47 / Chapter 2.1.7 --- Reagents and buffers for cell growth assays --- p.48 / Chapter 2.1.8 --- Reagents and buffers for flow cytometry --- p.48 / Chapter 2.1.9 --- Reagents and buffers for acetylcholine esterase activity assay --- p.50 / Chapter 2.1.10 --- Reagents and buffers for immunocytochemistry --- p.51 / Chapter 2.1.11 --- Reagents and buffers for total RNA extraction --- p.53 / Chapter 2.1.12 --- Reagents and buffers for reverse transcription --- p.54 / Chapter 2.1.13 --- Reagents for quantitative real-time polymerase chain reaction (qRT-PCR) --- p.56 / Chapter 2.1.14 --- Reagents and buffers for Western blotting --- p.59 / Chapter 2.1.15 --- Assay kits --- p.65 / Chapter 2.2 --- Methods --- p.68 / Chapter 2.2.1 --- Culture of cells --- p.68 / Chapter 2.2.2 --- MTT assay --- p.69 / Chapter 2.2.3 --- Cell proliferation assay --- p.70 / Chapter 2.2.4 --- Trypan blue exclusion test --- p.70 / Chapter 2.2.5 --- Cytotoxicity assay --- p.71 / Chapter 2.2.6 --- Colony-forming assay --- p.72 / Chapter 2.2.7 --- Cell cycle analysis --- p.72 / Chapter 2.2.8 --- Assessment of apoptosis --- p.73 / Chapter 2.2.9 --- Caspase activity determination --- p.74 / Chapter 2.2.10 --- Mitochondrial mass assay --- p.75 / Chapter 2.2.11 --- Reactive oxygen species (ROS) assay --- p.75 / Chapter 2.2.12 --- Mitochondrial membrane potential determination --- p.76 / Chapter 2.2.13 --- Morphological detection of cell differentiation --- p.76 / Chapter 2.2.14 --- Acetylcholine esterase activity determination --- p.77 / Chapter 2.2.15 --- Immunocytochemistry --- p.77 / Chapter 2.2.16 --- RNA interference --- p.78 / Chapter 2.2.17 --- Wound healing assay --- p.79 / Chapter 2.2.18 --- Tube formation assay --- p.79 / Chapter 2.2.19 --- In vivo Matrigel plug assay --- p.80 / Chapter 2.2.20 --- Phospho-VEGFR2 Sandwich ELISA assay --- p.80 / Chapter 2.2.21 --- Isolation of total cellular RNA --- p.81 / Chapter 2.2.22 --- Reverse transcription (RT) --- p.82 / Chapter 2.2.23 --- Quantitative real-time PCR --- p.83 / Chapter 2.2.24 --- Total protein extraction --- p.84 / Chapter 2.2.25 --- Protein concentration determination --- p.84 / Chapter 2.2.26 --- Sodium dodecyl sulphate-Polyacrylamide gel electrophoresis (SDS-PAGE) --- p.85 / Chapter 2.2.27 --- Semi-dry Western blotting --- p.85 / Chapter 2.2.28 --- Enhanced chemiluminescence (ECL) assay --- p.87 / Chapter 2.2.29 --- Molecular docking --- p.87 / Chapter 2.2.30 --- Statistical analysis --- p.88 / Chapter Three / Modulatory effects and action mechanisms of indirubin-3'-oxime on human neuroblastoma cells --- p.89 / Chapter 3.1 --- Introduction --- p.90 / Chapter 3.2 --- Results --- p.94 / Chapter 3.2.1 --- Indirubin-3’-oxime inhibited the growth and colony formation of human neuroblastoma cells in vitro --- p.94 / Chapter 3.2.2 --- Indirubin-3’-oxime exhibited no significant cytotoxicity on normal cells --- p.101 / Chapter 3.2.3 --- Indirubin-3’-oxime induced G0/G1 cell cycle arrest in LA-N-1 cells --- p.103 / Chapter 3.2.4 --- Indirubin-3’-oxime caused mitochondrial dysfunction in LA-N-1 cells --- p.106 / Chapter 3.2.5 --- Indirubin-3’-oxime selectively reduced ERR γ and PGC-1β protein and mRNA levels in LA-N-1 cells --- p.111 / Chapter 3.2.6 --- Indirubin-3’-oxime induced cell cycle arrest at G0/G1 phase and apoptosis of SH-SY5Y cells --- p.113 / Chapter 3.2.7 --- Indirubin-3’-oxime reduced mitochondrial mass and elevated mitochondrial ROS level in SH-SY5Y cells --- p.115 / Chapter 3.2.8 --- Indirubin-3’-oxime increased the caspase 8, caspase 9 and caspase 3/7 activities in SH-SY5Y cells --- p.117 / Chapter 3.3 --- Discussion --- p.119 / Chapter Four / Modulatory effects and action mechanisms of tryptanthrin on human neuroblastoma cells --- p.125 / Chapter 4.1 --- Introduction --- p.126 / Chapter 4.2 --- Results --- p.129 / Chapter 4.2.1 --- Tryptanthrin inhibited the cell growth and colony formation of human neuroblastoma cells --- p.129 / Chapter 4.2.2 --- Tryptanthrin exhibited no significant cytotoxicity on normal cells --- p.136 / Chapter 4.2.3 --- Tryptanthrin induced cell cycle arrest at G0/G1 phase --- p.138 / Chapter 4.2.4 --- Tryptanthrin induced apoptosis of LA-N-1 cells --- p.140 / Chapter 4.2.5 --- Tryptanthrin induced morphological neuronal differentiation in LA-N-1 cells --- p.143 / Chapter 4.2.6 --- Tryptanthrin induced the expression of neuronal differentiation markers --- p.146 / Chapter 4.2.7 --- Tryptanthrin down-regulated the expression of N-myc in LA-N-1 cells --- p.149 / Chapter 4.3 --- Discussion --- p.152 / Chapter Five / Anti-angiogenesis effects and action mechanisms of indirubin-3'-oxime and tryptanthrin --- p.158 / Chapter 5.1 --- Introduction --- p.159 / Chapter 5.2 --- Results --- p.163 / Chapter 5.2.1 --- Indirubin-3’-oxime and tryptanthrin inhibited the proliferation of endothelial cells --- p.163 / Chapter 5.2.3 --- Indirubin-3’-oxime and tryptanthrin reduced the tube formation of endothelial cells --- p.168 / Chapter 5.2.4 --- Indirubin-3’-oxime and tryptanthrin blocked angiogenesis in the in vivo Matrigel plug model --- p.171 / Chapter 5.2.5 --- Indirubin-3’-oxime and tryptanthrin reduced the angiogenic gene expression in endothelial cells --- p.174 / Chapter 5.2.6 --- Indirubin-3’-oxime and tryptanthrin attenuated VEGFR2-mediated signaling pathways in endothelial cells --- p.176 / Chapter 5.2.7 --- Indirubin-3’-oxime bound to the ATP-binding site of VEGFR2 kinase domain --- p.181 / Chapter 5.2.8 --- Tryptanthrin bound to the ATP-binding site of VEGFR2 kinase domain --- p.182 / Chapter 5.3 --- Discussion --- p.184 / Chapter Six / Conclusions and future perspectives --- p.191 / References --- p.206

Yip, Hon Yan Kelvin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 218-242). / Abstracts in English and Chinese. / ACKNOWLEDGEMENTS --- p.i / ABBREVIATIONS --- p.ii / ABSTRACT --- p.vii / CHINESE ABSTRACT (摘要） --- p.xi / PUBLICATIONS --- p.xiv / TABLE OF CONTENTS --- p.xv / Chapter CHAPTER 1: --- GENERAL INTRODUCTION --- p.1 / Chapter 1.1 --- Neuroblastoma --- p.2 / Chapter 1.1.1 --- An overview of neuroblastoma --- p.2 / Chapter 1.1.2 --- Epidemiology of neuroblastoma --- p.3 / Chapter 1.1.3 --- Clinical presentations of neuroblastoma --- p.5 / Chapter 1.1.4 --- Diagnosis and clinical assessment of neuroblastoma --- p.8 / Chapter 1.1.5 --- Staging of neuroblastoma --- p.10 / Chapter 1.1.6 --- Genetic aberrations of neuroblastoma --- p.12 / Chapter 1.1.7 --- Therapies of neuroblastoma --- p.15 / Chapter 1.2 --- Banlangen alkaloids --- p.20 / Chapter 1.2.1 --- An overview of Banlangen alkaloids --- p.20 / Chapter 1.2.2 --- "Pharmacokinetics of indirubin, tryptanthrin and their derivatives" --- p.24 / Chapter 1.2.2.1 --- Bioavailability of indirubin and its derivatives --- p.24 / Chapter 1.2.2.2 --- Toxicity of indirubin and its derivatives --- p.25 / Chapter 1.2.2.3 --- Bioavailability of tryptanthrin --- p.26 / Chapter 1.2.2.4 --- Toxicity of tryptanthrin --- p.27 / Chapter 1.2.3 --- "Pharmacological effects of indirubin, tryptanthrin and their derivatives" --- p.28 / Chapter 1.2.3.1 --- Selective inhibitor on kinases --- p.29 / Chapter 1.2.3.2 --- Anti-inflammatory activities --- p.31 / Chapter 1.2.3.3 --- Anti-tumour activities --- p.32 / Chapter 1.2.3.3.1 --- Anti-leukemic activity --- p.32 / Chapter 1.2.3.3.2 --- Apoptosis-inducing activity --- p.34 / Chapter 1.2.3.4 --- Anti-viral properties --- p.37 / Chapter 1.2.3.5 --- Anti-microbial properties --- p.37 / Chapter 1.3 --- Aims and Scope of This Study --- p.39 / Chapter CHAPTER 2: --- MATERIALS AND METHODS --- p.41 / Chapter 2.1 --- Materials --- p.42 / Chapter 2.1.1 --- Cell lines --- p.42 / Chapter 2.1.2 --- "Cell culture media, reagents and buffers" --- p.43 / Chapter 2.1.3 --- General staining solutions --- p.46 / Chapter 2.1.4 --- Drugs and chemicals --- p.47 / Chapter 2.1.5 --- Reagent for primary cultures preparation --- p.48 / Chapter 2.1.6 --- Reagents for cell proliferation assay --- p.48 / Chapter 2.1.7 --- Reagents for DNA extraction --- p.50 / Chapter 2.1.8 --- Reagents for gel electrophoresis of nucleic acids --- p.51 / Chapter 2.1.9 --- Reagents and buffers for flow cytometry --- p.53 / Chapter 2.1.10 --- Reagents and buffers for measuring caspase activity --- p.54 / Chapter 2.1.11 --- "Reagents, buffers and materials for Western blot analysis" --- p.58 / Chapter 2.1.12 --- Reagent for Hoechst staining --- p.68 / Chapter 2.2 --- Methods --- p.69 / Chapter 2.2.1 --- Culture of cell lines --- p.69 / Chapter 2.2.2 --- Determination of cell viability --- p.70 / Chapter 2.2.3 --- Determination of cell proliferation by tritiated thymidine ([ 3H]-TdR) incorporation assay --- p.72 / Chapter 2.2.4 --- "Isolation, culture and cytotoxicity test of murine peritoneal macrophages" --- p.73 / Chapter 2.2.5 --- "Isolation, culture and cytotoxicity test of murine bone marrow cells" --- p.74 / Chapter 2.2.6 --- Cytotoxicity test of primary cortical neurons from SD rats --- p.75 / Chapter 2.2.7 --- Determination of colony forming ability --- p.75 / Chapter 2.2.8 --- Analysis of cell cycle profile /DNA content by flow cytometry --- p.76 / Chapter 2.2.9 --- Detection of DNA fragmentation by agarose gel electrophoresis --- p.77 / Chapter 2.2.10 --- Quantitative detection of DNA fragmentation by Cell Death ELISAplus kit --- p.78 / Chapter 2.2.11 --- Detection of intracellular reactive oxygen species (ROS) generation --- p.80 / Chapter 2.2.12 --- Measurement of caspase activity --- p.81 / Chapter 2.2.13 --- Hoechst 33342 staining --- p.83 / Chapter 2.2.14 --- Cell morphological study --- p.83 / Chapter 2.2.15 --- Analysis of morphological changes by flow cytometry --- p.84 / Chapter 2.2.16 --- Assay for acetylcholine esterase (AChE) activity --- p.85 / Chapter 2.2.17 --- Protein expression study --- p.86 / Chapter 2.2.18 --- Statistical analysis --- p.89 / Chapter CHAPTER 3: --- IN VITRO STUDIES ON THE ANTI PROLIFERATIVE EFFECT OF INDIRUBIN-3'-OXIME AND TRYPTANTHRIN ON NEUROBLASTOMA CELLS --- p.90 / Chapter 3.1 --- Introduction --- p.91 / Chapter 3.2 --- Results --- p.95 / Chapter 3.2.1 --- Effects of indirubin-3'-oxime and tryptanthrin on the proliferation of human and the murine neuroblastoma cells --- p.95 / Chapter 3.2.2 --- Kinetic and reversibility studies of the anti-proliferative effect of indirubin-3'-oxime and tryptanthrin on the murine neuroblastoma Neuro-2a BU-1 cells --- p.107 / Chapter 3.2.3 --- Cytotoxic effect of indirubin-3'-oxime and tryptanthrin on the murine neuroblastoma Neuro-2a BU-1 cells --- p.115 / Chapter 3.2.4 --- Effects of indirubin-3'-oxime and tryptanthrin on the clonogenicity of the murine neuroblastoma Neuro-2a BU-1 cells --- p.120 / Chapter 3.2.5 --- Cytotoxicity of indirubin-3'-oxime and tryptanthrin on primary cells --- p.123 / Chapter 3.2.6 --- Effects of tryptanthrin on the cell cycle profile and expression of cyclins and cyclin-dependent kinases (CDKs) in the murine neuroblastoma Neuro-2a BU-1 cells --- p.132 / Chapter 3.2.7 --- Effect of indirubin-3'-oxime on the cell cycle profile in the murine neuroblastoma Neuro-2a BU-1 cells --- p.133 / Chapter 3.3 --- Discussion --- p.142 / Chapter CHAPTER 4: --- IN VITRO STUDIES ON THE APOPTOSIS-INDUCING EFFECT OF INDIRUBIN-3'-OXIME ON NEUROBLASTOMA CELLS --- p.150 / Chapter 4.1 --- Introduction --- p.151 / Chapter 4.2 --- Results --- p.156 / Chapter 4.2.1 --- Induction of DNA fragmentation in the indirubin-3'-oxime-treated murine neuroblastoma Neuro-2a BU-1 cells --- p.156 / Chapter 4.2.2 --- Induction of chromatin condensation in the indirubin-3 '-oxime-treated murine neuroblastoma Neuro-2a BU-1 cells --- p.160 / Chapter 4.2.3 --- Induction of caspase activities in the indirubin-3 '-oxime-treated murine neuroblastoma Neuro-2a BU-1 cells --- p.162 / Chapter 4.2.4 --- Induction of Reactive Oxygen Species (ROS) in the indirubin-3' -oxime-treated murine neuroblastoma Neuro-2a BU-1 cells --- p.169 / Chapter 4.2.5 --- Expression of pro-apoptotic and anti-apoptotic proteins in the indirubin-3 '-oxime-treated murine neuroblastoma Neuro-2a BU-1 cells --- p.173 / Chapter 4.3 --- Discussion --- p.177 / Chapter CHAPTER 5: --- STUDIES ON THE DIFFERENTIATION-INDUCING ACTIVITY OF TRYPTANTHRIN ON NEUROBLASTOMA CELLS --- p.188 / Chapter 5.1 --- Introduction --- p.189 / Chapter 5.2 --- Results --- p.193 / Chapter 5.2.1 --- Effects of tryptanthrin on the cell size and cellular complexity of the murine neuroblastoma Neuro-2a BU-1 cells --- p.193 / Chapter 5.2.2 --- Morphological studies on tryptanthrin-treated murine neuroblastoma Neuro-2a BU-1 cells --- p.196 / Chapter 5.2.3 --- Effect of tryptanthrin on the acetylcholine esterase (AChE) activity in the murine neuroblastoma Neuro-2a BU-1 cells --- p.198 / Chapter 5.2.4 --- Effects of tryptanthrin on the expression of tau protein and other mediators involved in the differentiation pathway --- p.200 / Chapter 5.3 --- Discussion --- p.204 / Chapter CHAPTER 6: --- CONCLUSIONS AND FUTURE PERSPECTIVES --- p.209 / REFERENCES --- p.218

published_or_final_version / Biochemistry / Master / Master of Science

published_or_final_version / Chinese Medicine / Master / Master of Philosophy

No description available.

published_or_final_version / Biochemistry / Doctoral / Doctor of Philosophy

Baicalein is known to be a potent antifungal agent and induces programmed cell death in Candida albicans. In the present study, we found that baicalein also inhibited the growth of C. krusei isolates. The minimal inhibitory concentrations of baicalein against eight C. krusei isolates were 1.35--2.70 microg/ml. One-hour exposure to baicalein elicited a consistent and moderate post-antifungal effect on the C. krusei isolates. Further flow cytometric study demonstrated a depolarization of mitochondrial membrane potential. However, both the levels of reactive oxygen species and DNA fragmentation were not significantly changed after baicalein treatment in C. krusei. It can be concluded that the antifungal activity of baicalein was mitochondria-dependent in both C. krusei and C. albicans, but the antifungal mechanism was different. Reactive oxygen species may not play a direct role and baicalein does not initiate programmed cell death or apoptosis in C. krusei. The structure-activity relationship study showed that the three hydroxyl groups in baicalein were essential for its antifungal potency. / Candidiasis has become a serious infection with very high mortality and morbidity in the world if not providing effective treatments. However, due to clinical limitation and resistance of the current antifungal agents, there is an urgent need to search for novel antifungals. In this study, after screening a compound library (n=400) for antifungal activity, three members (metergoline, purpurin and baicalein) were chosen for further study. Their antifungal characteristics and the antifungal mechanisms were investigated. / Metergoline, a serotonin receptor antagonist, was found to have potent antifungal activity against the intrinsically fluconazole-resistant human fungal pathogen Candida krusei. The minimal inhibitory concentration and minimal fungicidal concentration of metergoline against C. krusei were 4 microg/ml and 8 microg/ml respectively. Metergoline induced post-antifungal effect. Significant synergism was found in combination of metergoline with amphotericin B by a checkerboard assay, which may be due to the perturbation of cell permeability and increase in the intracellular accumulation of antifungal agents. Metergoline also inhibited extracellular phospholipase production in C. krusei. To gain insights into the mechanisms, intracellular changes that accompany apoptosis were examined by flow cytometry and spectrophotometry. The results showed an increase in the level of reactive oxygen species, depolarization of mitochondrial membrane potential, phosphatidylserine externalization, and positive terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labelling in the metergoline-treated C. krusei . Taken together, we conclude that metergoline may promote apoptosis in C. krusei through reactive oxygen species production and perturbation in mitochondrial homeostasis, implying its antifungal potential to treat candidiasis. / The antifungal activity of purpurin, a natural red anthraquinone pigment in madder root (Rubia tinctorum L.), was evaluated against Candida isolates by a broth microdilution assay. The minimal inhibitory concentrations of purpurin against Candida species isolates were 1.28--5.12 microg/ml. Mechanistic studies indicated that purpurin inhibited energy-dependent efflux pumps of Candida isolates. Furthermore, purpurin demonstrated a depolarization of mitochondrial membrane potential, suggesting a possible linkage of the antifungal mechanism of purpurin to Candida apoptosis. / Kang, Kai. / Adviser: Fong Wing Ping. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 98-123). / 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. / Abstract also in Chinese.