published_or_final_version / Chinese Medicine / Doctoral / Doctor of Philosophy

Colorectal cancer is the third most common cancer and cause of death due to cancer in the United States. Death due to colorectal cancer is generally caused by hepatic metastasis rather than the primary tumor itself. The five-year survival rate is only 10% for patients whose colorectal cancer metastasized, which indicates the need for more effective therapies to treat colon cancer. The diet contains (1) preformed vitamin A as retinyl esters in animal-derived food sources and (2) provitamin A carotenoids in plant-derived food sources. Once absorbed, retinol is re-esterified and transported to the liver, the major site of vitamin A storage. Therefore, dietary vitamin A supplementation can increase retinol levels in the colon and liver, potentially affecting both primary colon tumors and liver metastases of the primary tumors. All-trans--retinoic acid (ATRA) is thought to regulate most of the effects of retinoids, via the ATRA/RAR/RARE pathway exerting an inhibitory effect on cancer growth and progression. As cancer progresses, colon cancer acquires the resistance to ATRA. The purpose of this study is to understand the mechanism by which retinol decreased the growth and progression of ATRA-resistant human colon cancer in vivo and in vitro. We first demonstrated that retinol decreased the growth of ATRA-resistant colon cancer cells by arresting cell cycle progression independent of the ATRA/RAR/RARE pathway. Next, we showed retinol inhibited ATRA-resistant human colon cancer cell invasion by decreasing MMP-2, -9 and PI3K activity in vitro. Finally, dietary vitamin A supplementation decreased the incidence and multiplicity of liver metastases in nude mice intrasplenically injected with ATRA-resistant human colon cancer cells. Taken together, these data suggest the possibility of dietary vitamin A supplementation for colon cancer therapy and prevention.

Secondly, we incorporate knowledge of the physiology, or how we expect the anatomy to change due to treatment. We can represent these changes using the Jacobian of the deformation, which describes the local size and type of change. This is used to regularise the registration, and can be incorporated simultaneously with the iterations of the registration. The final result is an accurate and robust registration result that is clinically useful for finding corresponding features on pre- and post-treatment datasets.

Background: Colorectal cancer is the third most common cancer and cause of related deaths worldwide. Early colorectal cancer diagnosis is vital in reducing incidence and mortality. There is a need for the development of non-invasive screening tools for enhancing the detection of the disease. Cancer specific peptides are useful cancer targeting agents that can be used to specifically improve early detection strategies. Several cancer targeting peptides have been identified. Previous work investigated the specific binding of three of these peptides (p.C, p.L and p.14) conjugated to quantum dots and were found to bind to colorectal cancer cell lines (HT-29 and Caco-2). However, their uptake, localization and biodistribution in an in vitro and in vivo colorectal cancer model have not been determined. This is essential in gaining an understanding for future diagnostic or therapeutic based applications. Primary Aim: The aim of this study was investigate the localization of three selected peptides p.C, p.L and p.14 conjugated to gold nanoparticles in an in vitro and in vivo colorectal cancer model using HRTEM. Methodology: The AuNP/peptide conjugates were characterized by HRTEM and DLS. For in vitro studies; HT-29, Caco-2 and C3A cells were exposed to the AuNP-p.C, AuNP-p.L and AuNP-p.14, collected and processed for HRTEM to assess targeting and localization. For in vivo studies; the establishment of a colorectal cancer model using the AOM/DSS model 1 and 2 was conducted. Wistar rats were assigned to 6 groups, five experimental and 1 control group. Group 1 received AOM/DSS method 1 and was treated with AuNP-p.L. Group 2 and 3 received AOM/DSS method 2 and were treated with AuNP-p.C and AuNP-p.14. Group 4 and 5 remained healthy and treated with AuNP-p.C and AuNP-p.14. Group 6 remained healthy receiving no nanoparticle treatment. After treatment, rats were sacrificed and tissue was processed for HRTEM. Tissue chosen for HRTEM analysis included: Group 1 (inflamed colon, rectum, pancreatic and kidney), Group 4 (kidney) and Group 5 (liver). Results: results obtained from nanoparticle characterization suggested that nanoparticles were conjugated to their respective peptides and were stable in dispersion. For in vitro studies, results suggested no AuNP targeting and localization in HT-29 cell lines. For in vivo studies, no colorectal cancer tumours were induced. TEM micrographs did not indicate the presence of nanoparticles in colon, rectum, pancreatic, kidney and liver tissue. However, AuNPs were found in the kidney tissue (group 4). Conclusion: Although the overall objectives were not met, this study provided insight into TEM cell preparation and optimization for future nanoparticle cell interaction research. This study also demonstrated the absence of AuNPs in healthy tissue and the presence of AuNPs in healthy kidney tissue through renal clearance, a favourable quality for diagnostic or therapeutic applications.

Liu Bonnie Pui-ling. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 134-163). / Abstracts in English and Chinese. / Acknowledgments --- p.i / Abbreviations --- p.ii / Abstract / English --- p.1 / Chinese --- p.3 / Chapter Chapter 1 --- General Introduction / Chapter 1.1 --- Colorectal Cancer Statistics --- p.5 / Chapter 1.2 --- Colon Cancer --- p.5 / Chapter 1.3 --- Treatment --- p.6 / Chapter 1.4 --- Effects of Cytotoxic Drug Treatment --- p.7 / Chapter 1.5 --- Cell Cycle --- p.8 / Chapter 1.6 --- Oxidases --- p.9 / Chapter 1.7 --- Chemistry of Novel β-carboline: Tangutorine --- p.11 / Chapter 1.8 --- Aim of Study --- p.14 / Chapter Chapter 2 --- Cytotoxicity / Chapter 2.1 --- Introduction --- p.15 / Chapter 2.2 --- Materials and Methods --- p.18 / Chapter 2.3 --- Results --- p.23 / Chapter 2.4 --- Discussion --- p.44 / Chapter Chapter 3 --- Oxidase Activity and Protein Oxidation / Chapter 3.1 --- Introduction --- p.48 / Chapter 3.2 --- Materials and Methods --- p.54 / Chapter 3.3 --- Results --- p.60 / Chapter 3.4 --- Discussion --- p.80 / Chapter Chapter 4 --- Cell Cycle / Chapter 4.1 --- Introduction --- p.89 / Chapter 4.2 --- Materials and Methods --- p.93 / Chapter 4.3 --- Results --- p.96 / Chapter 4.4 --- Discussion --- p.118 / Chapter Chapter 5 --- General Discussion --- p.126 / References --- p.134

Colon cancer is one of the most common cancers in both the United States (US) and throughout the world. Over the last 30 years, despite the development of multiple classes of effective anti-tumor agents, colon cancer has consistently remained the second leading cause of mortality amongst all cancers and is today responsible for over 50,000 deaths a year in the US alone. Among the greatest challenges to the successful treatment of colon cancer is its heterogeneity in terms of drug-sensitivity, whereby it is often difficult to identify which patients will benefit from a specific class of anti-tumor agents before treatment has begun. It is therefore imperative to identify predictive biomarkers that can be leveraged to distinguish which colon tumors are most likely to respond to individual anti-cancer drugs. This will help develop new therapeutic algorithms that can maximize patient survival by rapidly matching individual patients with the specific treatment combinations that are most likely to benefit them as well as sparing them the toxicities from drugs that would be ineffective. Previous studies have reported that human colon carcinomas lacking expression of the caudal-type homeobox 2 (CDX2) transcription factor can be leveraged as a predictor of benefit from adjuvant chemotherapy containing 5-fluorouracil (5-FU). Lack of CDX2 expression associates with microsatellite instability (MSI), as well as several histopathological and molecular features that associate with exceptionally poor prognosis such as poor differentiation, lympho-vascular invasion, and BRAF mutation. However, the molecular mechanisms linking lack of CDX2 expression with increased drug sensitivity are currently unknown. In the first section of this study, we conducted a high throughput screen (HTS) aimed at identifying clinically approved anti-tumor drugs that display selective activity against colon carcinomas lacking CDX2 expression (CDX2-negative). The results of our screening, which compared an isogenic pair of CDX2+/+ and CDX2-/- cell lines generated by genetic inactivation of CDX2 using CRISPR/Cas9 constructs, revealed that CDX2-negative colon cancer cells display increased sensitivity to anti-tumor drugs that are substrates of the ATP binding cassette sub-family B member 1 (ABCB1) transporter. ABCB1 is a drug-efflux protein known for its capacity to extrude multiple classes of anti-tumor agents from the cytoplasm, therefore contributing to drug-resistance in cancer cells. Importantly, analysis of CDX2 and ABCB1 expression in two independent gene-expression databases (NCBI-GEO: n=2115; TCGA: n=478) revealed that a lack of CDX2 expression is invariably associated with lack of ABCB1 expression in human primary colon carcinomas. Furthermore, our molecular studies revealed that forced expression of CDX2 in human CDX2-negative colon cancer cells was capable of inducing expression of ABCB1, while genetic inactivation of CDX2 in human CDX2-positive cancer cells using CRISPR/Cas9 constructs resulted in loss of ABCB1 expression, thus establishing CDX2 as a direct mechanistic regulator of ABCB1 expression. Amongst all of the anti-tumor drugs identified as being ABCB1 substrates with preferential activity against CDX2-negative colon cancer cells, we observed that paclitaxel was the FDA-approved drug with the greatest degree of selectivity with a 10-fold difference in IC50. When tested in vivo against a collection of human patient derived xenograft (PDX) lines representative of both CDX2-negative and CDX2-positive colon carcinomas, paclitaxel displayed selective activity against CDX2-negative models, often inducing volumetric regression of established lesions. Our study, therefore, identified paclitaxel as a clinically approved anti-tumor agent that should be investigated for use in the treatment of CDX2-negative colon carcinomas. In the second portion of our study, we sought to conduct a preliminary evaluation of the possibility of using immune checkpoint inhibitors (ICIs) for the treatment of CDX2-negative colon carcinomas. ICIs have been shown to display substantial anti-tumor activity against colon carcinomas with microsatellite instability (MSI) and against epithelial malignancies over-expressing the immune-suppressive molecule PD-L1/CD274. Because CDX2-negative tumors are enriched for MSI and high levels of PD-L1/CD274, they are predicted to include a subgroup that is responsive to ICIs. However, not all MSI tumors respond to ICIs and, contrary to the majority of MSI tumors, the subgroup of MSI tumors characterized by a CDX2-negative phenotype is often associated with poor prognosis. Because the clinical activity of ICIs is dependent upon expression of class-I HLA molecules by tumor cells, we decided to evaluate whether CDX2-negative tumors were associated with inactivating mutations in class-I HLA genes. Our attention focused on a highly conserved poly-cytosine repeat region in the coding sequence of HLA-A (c.621_627) and HLA-B (c.621_626) genes. Because this sequence fulfilled the molecular definition of microsatellite, we predicted it to be highly susceptible to frameshift mutations (insertions or deletions) in MSI colon tumors. Indeed, a search across three independent genetic databases (TCGA, COSMIC, EBI) confirmed that this highly conserved poly-cytosine repeat region was targeted by recurrent and deleterious mutations in at least one HLA-A or HLA-B allele of at least 13% (n=21/156) of human MSI colon tumors, as compared to 0.3% (n=2/770) of human colon tumors with a microsatellite stable (MSS) phenotype (p<0.0001). Among tumors assessable for CDX2 expression, this specific type of class-I HLA mutations was more frequent among CDX2-negative (12%; n=6/49) as compared to CDX2-positive (1.5%; n=5/340) colon tumors (p<0.001), but was similar within MSI CDX2-negative (21%; n=6/28) and MSI CDX2-positive (17%; n=5/30) subgroups. In summary, this work achieved two main results: 1) it identified paclitaxel, a clinically approved anti-tumor drug, as a new treatment option for patients with CDX2-negative colon cancers, which represents an extremely aggressive subgroup of colorectal malignancies; 2) it revealed that, in human MSI colon tumors, class-I HLA genes are prone to recurrent frameshift mutations in a genomic hotspot, mutations that are likely to associate with tumor resistance to ICIs and that they are therefore likely to represent a new class of actionable predictive biomarkers for both MSI and CDX2-negative colon carcinomas. These findings will help advance our understanding of colon cancer biology, and hopefully improve treatment algorithms for the clinical management of colon cancer patients.

Bioengineered probiotics enable new opportunities to improve colorectal cancer (CRC) prevention, screening, and treatment strategies. With CRC incidence on the rise in younger populations, there is an increased need to engineer technologies that enhance patient access to diagnostic exams and disease management. This dissertation presents the development of an orally-delivered probiotic to screen for and treat early CRC lesions with a particular emphasis on translatability factors including: safety of probiotic use, exploration of oral delivery, and testing in clinically relevant models. At the interface of immunology, synthetic biology, and the microbiome fields is the overarching concept that microbes play a critical role in the tumor microenvironment (TME). The innate ability of bacteria to seek out tumor-specific signatures and proliferate within their necrotic cores due to reduced immune surveillance enables the precise immunoengineering of the local TME. Here, we will design, characterize, and test a probiotic encoded with a lysis mechanism to aid in biocontainment and maximize the release of recombinantly-produced diagnostic and immunotherapeutic cargo. In this lysis circuit, bacteria grow to a critical density within tumors and synchronously lyse, locally releasing their payload. A small fraction of bacteria remains to reseed the population and the cycle continues, resulting in repeated and sustained drug delivery. Drawing from advancements in immunology, we engineered bacteria to produce immune checkpoint inhibitors. Monoclonal antibodies targeting immune checkpoints have revolutionized cancer therapy, but only work in a subset of patients and can lead to a multitude of toxicities, suggesting the need for more targeted delivery systems. Due to their preferential colonization of tumors, bacteria are a natural chassis for the localized delivery of such therapeutics. Therefore, we engineered a commercially available probiotic, E.coli Nissle 1917 (EcN), for the controlled production and intratumoral release of nanobodies targeting programmed cell death protein – ligand 1 (PD-L1) and cytotoxic T- lymphocyte-associated protein-4 (CTLA-4) using the described lysing release mechanism. We demonstrate that a single injection of this engineered probiotic enhanced therapeutic response compared to analogous clinically-relevant antibodies, resulting in tumor regression in syngeneic mouse models. In an effort to create a more effective therapeutic for poorly immunogenic cancers, we utilized the modularity of our platform to slow tumor growth in mouse models of established CRC by combining it with a probiotically-produced cytokine, granulocyte-macrophage colony stimulating factor (GM-CSF). We sought to expand upon the relevance of this approach for early-stage CRC screening and treatment, by characterizing the platform in CRC precancerous lesions, or adenomas. When orally-delivered, EcN robustly colonized adenomas in genetically-engineered and orthotopic murine models of CRC, and human CRC patients. Leveraging adenoma-specific colonization, we probed for EcN presence in fecal matter, demonstrating its utility as a non-invasive screen for adenomas. For more accessible testing, we engineered EcN to produce salicylate and showed that it could be detected in the urine of tumor-bearing mice for days after oral delivery of the probiotic. Moreover, we demonstrated that the therapeutic effectiveness of our previously engineered therapeutic strain, producing PD-L1, CTLA-4 and GM-CSF, was maintained when delivered orally, ultimately resulting in significant adenoma reduction. Altogether, this dissertation aims to highlight the potential for engineered EcN to be used as a safe, orally-deliverable screening and therapeutic platform for early-stage CRC disease. While we have chosen to focus on CRC here, we will conclude by discussing efforts to adapt this platform to work in combination with other cellular therapies and therapeutic indications, ultimately engineering a platform to impact a broader patient population.

強心苷是一類多年普遍用於心力衰竭治療的化合物,包括蟾蜍靈和地高辛。鈉泵（也可稱為鈉鉀ATP酶）是強心苷的受體。最近流行病學研究，體外實驗，動物實驗和臨床試驗表明，強心苷具有癌症治療的強大潛力。 / 大腸癌是全球第三大殺手，約有一半的大腸癌患者需要手術切除後的輔助治療。因此，通過化療殺死腫瘤細胞，是一個可行的辦法來治療大腸癌患者。在本課題的研究中，強心苷抗人結腸癌的作用在HT-29和Caco-2細胞上進行了評價與闡釋。在結腸癌細胞研究模型中，蟾蜍靈誘導caspase非依賴性的細胞死亡，伴隨沒有早期凋亡，沒有聚（ADP-核糖）聚合酶(PARP)與caspase-3裂解，這些發現與強心苷誘發其它類腫瘤細胞凋亡的機製完全不同。相反，蟾蜍靈激活自噬途徑，促進LC3-II積累和自噬流動。此外，其它強心苷如地高辛與烏本苷也促使LC3-II在HT-29細胞內聚集。沉默ATG5和Beclin-1顯著降低蟾蜍靈誘導的LC3- II積累和細胞死亡。蟾蜍靈誘導的自噬與活性氧（ROS）產生和JNK活化相關。我們的研究結果揭示了蟾蜍靈藥物對抗結腸癌細胞的一種新的機制，開闢了強心苷通過自噬途徑來治療大腸癌的可能性。 / 最近的研究表明，強心苷誘導多種癌細胞系的細胞包括促使凋亡與自噬的細胞週期阻滯在G2／M期。然而，沒有詳細的信息闡述強心苷如何阻滯細胞週期進展。在本課題研究中，我們研究了強心苷介導的細胞週期阻滯的分子機制。蟾蜍靈處理的HeLa H2B-YFP細胞被阻滯在前中期，伴隨姐妹染色單體凝聚，染色體未排列在赤道板，未退出有絲分裂期。這一結果被蟾蜍靈誘導的四倍DNA含量細胞既不在四倍體G1期也不在胞質分裂期進一步證明。此後，我們檢測了紡錘體組裝和染色體分離所需的Aurora激酶和Polo-like kinase 1 (Plk1)。結果發現，在HT-29和HeLa細胞上，蟾蜍靈和其它強心苷能顯著降低總蛋白質和磷酸化的Aurora激酶與Plk1。此外，我們還發現，蟾蜍靈通過PI3K下調有絲分裂酶的活性。這些結果已經通過沉默鈉泵α做了驗證。總之，我們的結果表明, 蟾蜍靈和其它強心苷鈉鉀泵抑製劑強有力的抑制細胞在前中期是通過PI3K/HIF-1α/NF-κB途徑下調Aurora激酶的蛋白質和磷酸化水平和Plk1的蛋白質水平。我們的研究發現在了解如何利用強心苷的潛能治療癌症以及認知鈉泵在細胞週期中的功能方面提供了有用的信息。 / The sodium pump (also known as Na+/K+-ATPase) is the receptor for cardiac glycosides, a group of compounds including bufalin and digoxin which have been commonly used for heart failure treatment for many years. Recent epidemiological studies, in vitro studies, animal studies and clinical trials have shown that cardiac glycosides have potential applications for cancer treatment. / Colorectal cancer is the third leading cause of cancer death worldwide and about half of the patients with colorectal cancer require adjuvant therapy after surgical resection. Therefore, the eradication of cancer cells via chemotherapy constitutes a viable approach to treat patients with colorectal cancer. In this study, the effects of cardiac glycosides were evaluated and characterized in HT-29 and Caco-2 human colon cancer cells. Contrary to their well documented apoptosis-promoting activity in other cancer cells, bufalin did not cause caspase-dependent cell death in colon cancer cells, as indicated by the absence of significant early apoptosis, as well as poly(ADP-ribose) polymerase (PARP) and caspase-3 cleavage. Instead, bufalin activated an autophagy pathway, as characterized by the accumulation of LC3-II and the stimulation of autophagic flux. Moreover, other cardiac glycosides digoxin and ouabain could also induce the accumulation of LC3-II in HT-29 cells. The silencing of ATG5 and Beclin-1 significantly reduced bufalin-induced LC3-II accumulation and cell death. The induction of autophagy by bufalin was linked to the generation of reactive oxygen species (ROS) and JNK activation. My findings unveil a novel mechanism of drug action by bufalin in colon cancer cells and open up the possibility of treating colorectal cancer by cardiac glycosides through an autophagy pathway. / Recent studies have revealed that cardiac glycosides induce G2/M phase arrest in many cancer cells, which include apoptosis- and autophagy-promoting cells. However, no detailed information is available on how cardiac glycosides arrest cell cycle progression. In this study, I studied the molecular mechanisms of cell cycle arrest mediated by cardiac glycosides. Bufalin-treated HeLa H2B-YFP cells were arrested at prometaphase, as characterized by the presence of sister chromatid cohesion, absence of chromosomes alignment on the metaphase plate, and failure to exit mitosis. This result was further confirmed by bufalin-induced cells with 4N DNA content in neither tetraploid G1 phase nor cytokinesis. Thereafter, I detected the Aurora kinases and Polo-like kinase 1 (Plk1), which are required for both spindle assembly and chromosome segregation. It was found that bufalin and other cardiac glycosides could significantly reduce the total protein and phosphorylation of Aurora kinases and Plk1 in HT-29 and HeLa cells. In addition, I found that PI3K was responsible for the bufalin-induced downregulation of the activities of mitotic kinases. This result was validated by silencing of sodium pump alpha. Taken together, my results demonstrate that bufalin and other cardiac glycoside inhibitors of the sodium pump potently arrest cancer cells at prometaphase by downregulating the total protein and phosphorylation of Aurora kinases and the total protein of Plk1 through the PI3K/HIF-1α/NF-κB pathway. My findings provide useful information in understanding how cardiac glycosides could be exploited for their potentials in treating cancer and in identifying the function of sodium pump in cell cycle progression. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Xie, Chuanming. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 133-152). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Declaration of Originality --- p.i / Acknowledgements --- p.iii / Abstract --- p.vi / Abstract (in Chinese) --- p.viii / List of Abbreviations --- p.xiv / List of Figures --- p.xvi / List of Tables --- p.xix / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Cancer --- p.1 / Chapter 1.2 --- The chemical structure of cardiac glycosides --- p.2 / Chapter 1.3 --- The traditional use of cardiac glycosides in cardiology --- p.4 / Chapter 1.4 --- The role of cardiac glycosides in cancer treatment --- p.4 / Chapter 1.5 --- The mechanisms of action by cardiac glycosides in cancer --- p.5 / Chapter 1.5.1 --- The structure and functions of cardiac glycosides receptor sodium pump --- p.5 / Chapter 1.5.2 --- Sodium pump as anticancer target --- p.6 / Chapter 1.5.3 --- The signal pathways involved in anticancer effect of cardiac glycosides --- p.7 / Chapter 1.6 --- The role of cardiac glycosides in apoptosis and autophagy --- p.8 / Chapter 1.7 --- Objectives of this project --- p.12 / Chapter Chapter 2 --- Bufalin induces autophagy but not apoptosis in human colon cancer cells --- p.17 / Chapter 2.1 --- Introduction --- p.17 / Chapter 2.2 --- Materials and Methods --- p.19 / Chapter 2.2.1 --- Reagents and antibodies --- p.19 / Chapter 2.2.2 --- Cell culture --- p.19 / Chapter 2.2.3 --- Cell viability and cell death assay --- p.20 / Chapter 2.2.4 --- Annexin V and PI staining --- p.20 / Chapter 2.2.5 --- Cell cycle analysis --- p.21 / Chapter 2.2.6 --- Analysis of cleaved caspase-3-positive cells by flow cytometry --- p.21 / Chapter 2.2.7 --- Western blot analysis --- p.21 / Chapter 2.2.8 --- Immunofluorescence analysis of LC3 distribution --- p.22 / Chapter 2.2.9 --- RNA isolation and RT-PCR --- p.22 / Chapter 2.2.10 --- siRNAs transfection and treatments --- p.23 / Chapter 2.2.11 --- Transmission electron microscopy --- p.23 / Chapter 2.2.12 --- Statistical analysis --- p.24 / Chapter 2.3 --- Results --- p.24 / Chapter 2.3.1 --- Bufalin induces cell death and cell cycle arrest at G2/M phase in colon cancer cells --- p.24 / Chapter 2.3.2 --- Bufalin induces caspase-independent cell death in colon cancer cells --- p.28 / Chapter 2.3.3 --- Bufalin induces autophagy in colon cancer cells --- p.30 / Chapter 2.3.4 --- Bufalin-induced autophagy is dependent on ATG5 and Beclin-1 --- p.37 / Chapter 2.3.5 --- Increased autophagy is responsible for bufalin-induced cell death --- p.40 / Chapter 2.4 --- Discussion --- p.42 / Chapter Chapter 3 --- Bufalin mediates autophagic cell death through ROS generation and JNK activation --- p.44 / Chapter 3.1 --- Introduction --- p.44 / Chapter 3.2 --- Materials and Methods --- p.46 / Chapter 3.2.1 --- Reagents and antibodies --- p.46 / Chapter 3.2.2 --- Cell culture --- p.47 / Chapter 3.2.3 --- Cell viability and cell death assay --- p.47 / Chapter 3.2.4 --- Western blot analysis --- p.47 / Chapter 3.2.5 --- Quantification of cells with > 5 LC3 punctate staining --- p.47 / Chapter 3.2.6 --- siRNAs transfection and treatments --- p.48 / Chapter 3.2.7 --- RNA isolation and RT-PCR --- p.48 / Chapter 3.2.8 --- ROS analysis --- p.48 / Chapter 3.2.9 --- JC-1 staining --- p.49 / Chapter 3.2.10 --- Statistical analysis --- p.49 / Chapter 3.3 --- Results --- p.50 / Chapter 3.3.1 --- Bufalin induces autophagy-mediated cell death via ROS generation --- p.50 / Chapter 3.3.2 --- Activation of JNK is required for the upregulation of ATG5 and Beclin-1, and subsequent autophagy-mediated cell death in response to bufalin --- p.54 / Chapter 3.3.3 --- ROS generation is upstream of JNK activation in bufalin-induced cell death --- p.59 / Chapter 3.3.4 --- Bufalin-induced ROS generation is derived from mitochondria --- p.62 / Chapter 3.4 --- Discussion --- p.66 / Chapter Chapter 4 --- Bufalin arrests cells at prometaphase --- p.69 / Chapter 4.1 --- Introduction --- p.69 / Chapter 4.2 --- Materials and Methods --- p.70 / Chapter 4.2.1 --- Reagents and antibodies --- p.70 / Chapter 4.2.2 --- Cell synchronization --- p.70 / Chapter 4.2.3 --- Mitotic index analysis of phosphorylation of MPM2 --- p.71 / Chapter 4.2.4 --- Cell cycle analysis --- p.71 / Chapter 4.2.5 --- Time-lapse experiments --- p.71 / Chapter 4.2.6 --- Immunofluorescence analysis of phospho-histone H3 (Ser10) --- p.72 / Chapter 4.2.7 --- Western blot analysis --- p.73 / Chapter 4.3 --- Results --- p.73 / Chapter 4.3.1 --- Bufalin reduces mitotic marker phosphorylation of histone H3 and MPM2 and increases cells with 4N DNA content --- p.73 / Chapter 4.3.2 --- Increased cells with 4N DNA content after bufalin treatment are in neither a tetraploid G1 phase nor a cytokinesis arrest --- p.77 / Chapter 4.3.3 --- Bufalin-treated cells can enter prophase, but fail to pass through metaphase --- p.80 / Chapter 4.4 --- Discussion --- p.83 / Chapter Chapter 5 --- Bufalin induces prometaphase arrest through downregulating mitotic kinases --- p.87 / Chapter 5.1 --- Introduction --- p.87 / Chapter 5.2 --- Materials and Methods --- p.89 / Chapter 5.2.1 --- Reagents and antibodies --- p.89 / Chapter 5.2.2 --- Cell synchronization --- p.90 / Chapter 5.2.3 --- Immunofluorescence staining --- p.90 / Chapter 5.2.4 --- siRNAs transfection and treatments --- p.91 / Chapter 5.2.5 --- Western blot analysis --- p.91 / Chapter 5.2.6 --- Statistic analysis --- p.91 / Chapter 5.3 --- Results --- p.92 / Chapter 5.3.1 --- Bufalin downregulates Aurora A and B in protein and phosphorylation levels --- p.92 / Chapter 5.3.2 --- Bufalin prevents Aurora A recruitment to mitotic centrosomes and Aurora B recruitment to unattached kinetochores --- p.97 / Chapter 5.3.3 --- Bufalin prevents Plk1 recruitment to mitotic centrosomes and unattached kinetochores through downregulation of protein levels of Plk1 --- p.101 / Chapter 5.3.4 --- Bufalin decreases the activities of Aurora A, Aurora B and Plk1 through PI3K pathway --- p.105 / Chapter 5.3.5 --- HIF-1α and NF-κB pathways are involved in sodium pump-mediated the regulation of mitotic kinases --- p.109 / Chapter 5.4 --- Discussion --- p.112 / Chapter Chapter 6 --- General discussion --- p.115 / Chapter 6.1 --- Potential toxicity of bufalin --- p.115 / Chapter 6.2 --- Cardiac glycosides induced programmed cell death --- p.115 / Chapter 6.3 --- Signal pathways involved in cardiac glycosides-mediated autophagy --- p.117 / Chapter 6.4 --- The relationship between ROS and JNK in cardiac glycosides-induced autophagy --- p.120 / Chapter 6.5 --- The role of ROS in apoptosis and autophagy --- p.121 / Chapter 6.6 --- The role of cardiac glycosides in cell cycle arrest --- p.122 / Chapter 6.7 --- Application of cardiac glycosides in combination with chemotherapy and radiotherapy --- p.125 / Chapter Chapter 7 --- Conclusions and future perspectives --- p.127 / References --- p.133 / Appendices --- p.153 / Publication --- p.153

A 24-hour fermentation of the optimized synbiotic composed of B. longum and EPR was performed to give a cell-free fermentation broth (S24). S24 was co-cultured with two colon cancer cell lines (Caco-2 and SW620) and normal colon cells (FHC). S24 significantly inhibited cell proliferation for both colon cancer cells but promoted FHC cell growth by 10-25% as shown by MTT and BrdU arrays. Primary DNA damage analysis by alkaline comet assay showed S24 caused DNA damage to a comparable extent as the positive control of 10 mM H2O2 (treated for 1 hour) for both cancer cells. Dynamic analysis on DNA damage-associated DNA repair showed the two colon cancer cells had different response pattern to S24. Flow cytometric analysis showed that both Caco-2 and SW620 when treated with S24 (IC 50=3.66 mM of acetate) were arrested initially at G2/M and subsequently at S phase accompanied with large sub-G1 peaks. Dual staining with PI/AnnexinV further proved the appearance of apoptosis. Live cell imaging analysis on Caco-2 cells treated with S24 showed the following events: mitochondria were rapidly destroyed within the first two-hour treatment, the cells bubbled and the nucleus condensed after the mitochondrial had shrunken, followed by apoptosis. / Despite active research on synbiotic on anti-carcinogenesis of colon cancer by synbiotics, the underlying mechanism still remains unclear. This study investigated a novel synbiotic composed of non-digestible carbohydrates (NDCs) extracted from mushroom sclerotia as prebiotics and Bifidobacteria as probiotics. Preliminary results on incubation of two probiotics ( Bifidobacterium longum and Lactobacillus brevis) and one pathogenic bacterium (Clostridium celatum) separately with 3 NDCs extracted from mushroom sclerotia [Poria cocos (PC), Polyporus rhinocerus (PR) and Pleurotus tuber-regium (PT)] indicated that the growth of B. longum and L. brevis was stimulated more preferentially than C. celatum after 72-hour fermentation. The short-chain fatty acid (SCFA) profile was dominated by acetate (> 98% of total SCFAs) with very little butyrate (&lt; 2.0% of total SCFAs) and the organic matter disappearance (OMD) during fermentation was consistent with the bacterial growth. Among the synbiotic combinations, NDC from PR and B. longum gave the largest amount of acetate (2.47+/-0.232 mmol/g of organic matter disappearance). / Results obtained from human pathway finder RT2 Profiler(TM) PCR Array indicated that S24 could modulate the proliferation of colon cancer cells mainly by various pathways such as cell cycle and DNA damage repair, apoptosis and cell senescence, etc. In SW620 cells, PCR Array of Human Cell Cycle further revealed that the modulated genes mainly belonged to the gene cluster of S phase and DNA replication as well as G2 and G2/M transition. While for Caco-2 cells, the cell-cycle modulated genes mainly belonged to the cluster of G2 and G2/M transition. Immuno-blotting on the pivotal upstream regulators showed that phosphorylation of ATM at Serine 1981 was significantly increased in both cancer cells. Site-specific phosphorylation of pRB was decreased and phosphorylation of Chk1 was increased in both cancer cells while Chk2 were increased in SW620 cells. Cdc25A was phosphorylated at serine17 in both cancer cells. It can be proposed that the blockage of DNA synthesis or DNA damage was due to the down-regulation of some pivotal DNA replication related proteins such as RPA3, PCNA and MCMs, detected by ATM-Chk1/Chk2-Cdc25A pathway. This would cause the prolonged staying of cells at the G1/S checkpoint which further moved on to S phase arrest for SW620 cells. Moreover the sharply up-regulated p21, an important inhibitor of Cdk2 would further hinder the cells passing the G1/S checkpoint in SW620 cells. / The tumor suppressor p53 was detected phosphorylated at various sites in SW620 but not in Caco-2 cells. In SW620 cells, G2/M arrest was caused by the inhibition of CDK1/CDC2 due to increased expression of GADD45A and p21 and phosphorylation of Cdc25A, while for Caco-2, the G2/M arrest was caused by degradation of Cdc25A due to the absence of p53-activated GADD45A and p21 expression as shown in the pathway finder results. Some apoptosis-related proteins of Bax, Apaf-1 and PARP were modulated as shown by immuno-blotting in both colon cancer cells. (Abstract shortened by UMI.) / Gao, Shane. / Adviser: Peter Chi-Keung Cheung. / Source: Dissertation Abstracts International, Volume: 72-11, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 55-94). / 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.

Cheung, Wing Ki. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 100-112). / Abstracts in English and Chinese. / Acknowledgments / Abbreviations / Abstract 一 English --- p.i / - Chinese --- p.iii / Chapter Chapter 1 --- General Introduction / Chapter 1.1. --- Colon Cancer / Chapter 1.1.1. --- Colon cancer statistic in Hong Kong --- p.1 / Chapter 1.1.2. --- Development of Colon cancer --- p.1 / Chapter 1.1.3. --- Treatment --- p.2 / Chapter 1.2. --- Chemistry of ascorbates / Chapter 1.2.1. --- Sodium-L-ascorbate --- p.3 / Chapter 1.2.2. --- "Sodium 5,6-benazylidene-L-ascorbate" --- p.4 / Chapter 1.3. --- "Reactive oxygen species and reactive nitrogen species, and their biological consequences" --- p.5 / Chapter 1.4. --- Cell cycle --- p.7 / Chapter 1.5. --- Autophagy --- p.8 / Chapter 1.6. --- Human colon cancer HT29 cells for anti-tumor study --- p.9 / Chapter 1.7 --- Aim of study --- p.10 / Chapter Chapter 2 --- Comparative studies of cytotoxicity of SAA and SBA in short term treatment / Chapter 2.1. --- Introduction --- p.11 / Chapter 2.2. --- Materials and Methods --- p.14 / Chapter 2.3. --- Results --- p.17 / Chapter 2.4. --- Discussion --- p.26 / Chapter Chapter 3 --- Comparative studies of SAA and SBA in oxidative stress induction and their corresponding ROS inhibitors / Chapter 3.1. --- Introduction --- p.28 / Chapter 3.2. --- Materials and Methods --- p.31 / Chapter 3.3. --- Results --- p.35 / Chapter 3.4. --- Discussion --- p.42 / Chapter Chapter 4 --- "Effects of SAA and SBA treatments on cell cycle regulatory proteins and the induction of transient cell cycle arrests in Gl, S and G2 phases Cell Cycle" / Chapter 4.1. --- Introduction --- p.45 / Chapter 4.2. --- Materials and Methods --- p.49 / Chapter 4.3. --- Results --- p.53 / Chapter 4.4. --- Discussion --- p.69 / Chapter Chapter 5 --- Autophagy induction during SBA treatment and autophagy inhibition during SAA treatment / Chapter 5.1. --- Introduction --- p.72 / Chapter 5.2. --- Materials and Methods --- p.74 / Chapter 5.3. --- Results --- p.77 / Chapter 5.4. --- Discussion --- p.91 / Chapter Chapter 6 --- General Discussion --- p.93 / References --- p.100