The objective of this study was to investigate food consumption frequency patterns, defecation habits, and incidence of disease states associated with colon cancer by active LDS adult males, residing in Texas, which may help explain the lower incidence of colon cancer observed in the religious group. To accomplish this objective, a sample of 50 was randomly selected and administered a questionnaire, designed to gather information covering personal and demographic characteristics, defecation habits, incidence of associated disease states, and frequency of consumption of 132 selected foods. Data was analyzed by comparison of percentages, means, and frequencies, and a Pearson Product Moment Correlation. Results reported LDS males chose a wide variety of foods with a high frequency of fruits, vegetables, and cereals. A low incidence of problems associated with colon cancer and "western" or refined diets was also reported. Defecation habits were more frequent than general population and compared favorably to another low-risk population, rural Scandinavians.

Eukaryotic translation elongation factor-2 (EEF2) is regulated through phosphorylation by a specific kinase known as eukaryotic elongation factor-2 kinase (EEF2K), leading to translational down regulation. Currently, it has been reported that EEF2K could promote the autophagic survival in breast and glioblastoma cell lines. However, the precise function of EEF2K in cancer as well as the related mechanism is still poorly understood. Colorectal cancer is the third common malignant disease worldwide and more than half of the patients with colorectal cancer require chemotherapy after surgery. However, de novo or acquired resistance to the agents is common. Discovery of novel targets for the chemotherapeutic intervention or treatment of colorectal cancer is highly warranted. In this study, the role of EEF2K as well as the underlying mechanism involved was evaluated in HT-29 and HCT-116 human colon cancer cells. Contrary to the reported autophagy-promoting activity of EEF2K in certain cancer cells, EEF2K is shown to negatively regulate autophagy in colon cancer cells as indicated by the increase of LC3-II levels, the accumulation of LC3 dots per cell, and the promotion of autophagic flux in EEF2K silenced cells. Moreover, the silencing of EEF2K promotes the cell viability, clonogenicity, cell proliferation and cell size in colon cancer cells. The silencing of BECN1 and ATG7 significantly reduce silencing of EEF2K induced LC3-II accumulation and cell survival. However, autophagy induced by EEF2K silencing does not potentiate the anticancer efficacy of the AKT inhibitor MK-2206. In addition, EEF2K overexpression decreases the cell survival and potentiates the antitumor efficacy of oxaliplatin. Autophagy induced by silencing of EEF2K is attributed to induction of protein synthesis, which results in ATP consumption and then actives AMPK-ULK1 pathway. This process appears independent of the suppression of MTOR activity and ROS generation. Silencing of AMPK or ULK1 significantly decreases EEF2K silencing-induced autophagy as well as cell survival in colon cancer cells. In conclusion, EEF2K negatively regulates autophagic survival through the AMPK-ULK1 pathway in colon cancer cells. This study provide useful information in understanding the role of EEF2K in colon cancer cells and suggests that upregulation of EEF2K activity may be developed a novel approach for the treatment of human colon cancer. / 真核延伸因子2激酶 (EEF2K) 通過磷酸化修飾真核延伸因子2 (EEF2) 來調控其活性，進而下調蛋白質翻譯延伸的速度。目前，有研究表明在乳腺癌和多形性膠質母細胞瘤中，EEF2K能夠誘導細胞自噬，並且這種類型的細胞自噬有助於細胞生存。然而，對於EEF2K在腫瘤中的精確作用以及它所涉及的分子機理仍然知之甚少，有待於進一步的研究。結直腸癌是全球第三大惡性腫瘤疾病，約有半數以上的患者需要手術後進行化學藥物治療。然而，患者對目前已有藥物的耐藥性十分普遍，因此，研發新的化學藥物靶點或者新的治療方法十分必要。在本課題研究中，EEF2K的功能及其所涉及的分子機理在人結腸癌細胞系HT-29和HCT-116上進行了闡釋。與在某些特定種類腫瘤細胞中EEF2K能夠誘導細胞自噬產生的現象相反，在EEF2K表達下調的人結腸癌細胞中，細胞自噬標記物LC3-II表達上升， 細胞中LC3斑點的聚集增多，並且細胞自噬流增強的現象，都表明EEF2K在這類腫瘤細胞中負調控細胞自噬。在結腸癌細胞中，EEF2K表達下調能夠增強細胞的活力，單細胞克隆的形成，細胞增殖以及細胞大小。此外，沈默BECN1和ATG7基因的表達都能夠減少EEF2K下調引發的LC3-II積累以及細胞增殖。然而，降低EEF2K表達所引發的細胞自噬並不能夠增強AKT抑制劑MK-2206抗腫瘤的效果。EEF2K的過表達能夠減少細胞增殖並且加強oxaliplatin的抗腫瘤藥效。沈默EEF2K引發的細胞自噬是通過誘導蛋白質的合成，導致ATP的消耗進而激活AMPK-ULK1細胞通路，與MTOR活性的抑制及ROS的產生無關。在結腸癌細胞中，降低AMPK或者ULK1的表達能夠消除EEF2K沈默所引起的LC3-II表達升高，細胞中LC3斑點聚集增多以及細胞增殖加強等現象。綜上所述，在人結腸癌細胞中，沈默EEF2K基因表達能夠通過激活AMPK-ULK1細胞通路，誘導有助於細胞存活的自噬現象產生。本課題研究對理解EEF2K在結腸癌細胞中的功能提供了有用的信息並且表明增強EEF2K的活性可以作為一種潛在的新的治療人結腸癌的方法。 / Liu, Xiaoyu. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 116-131). / Abstracts also in Chinese. / Title from PDF title page (viewed on 16, November, 2016). / Detailed summary in vernacular field only.

Colon cancer, a disease in which malignant tumors form in the tissues of colon, is the first commonest cancer and the second leading cause of cancer-related deaths in Hong Kong. The standard treatment options for colon cancer include surgery and chemotherapy. However, multidrug resistance (MDR) develops in nearly all patients with colon cancer. In fact, most of the cancer-related deaths are due to chemotherapy failure caused by MDR, which occurs during the course of cancer progression and chemotherapy. Thus, the reversal of MDR plays an important role in the successful chemotherapy for colon cancer. This study investigated such a pharmacological action in reversing MDR in colon cancer cells by tanshinones, targeting the two common mechanisms responsible for MDR, i.e. overexpression of ATP-binding cassette (ABC) transporters and suppression of apoptosis. / Overexpression of P-glycoprotein (P-gp), one of the most important ABC transporters, can mediate the efflux of drugs out of cancer cells, leading to MDR and chemotherapy failure. The reversal of P-gp-mediated MDR by five tanshinones including tanshinone I, tanshinone IIA, cryptotanshinone, dihydrotanshinone and miltirone was evaluated in colon cancer cells. Bi-directional transport assay showed that only cryptotanshinone and dihydrotanshinone decreased the P-gp-mediated digoxin efflux in Caco-2 cells. The two tanshinones potentiated the cytotoxicities of doxorubicin and irinotecan in P-gp overexpressing colon cancer SW620 Ad300 cells. Moreover, these two tanshinones also increased intracellular accumulation of P-gp substrate in SW620 Ad300 cells, presumably by down-regulating P-gp mRNA and protein levels, as well as inhibiting P-gp ATPase activity. / Suppression of apoptosis can lead to MDR in cancer cells to anticancer agents with pro-apoptotic property. Hence, this study also investigated the circumvention of resistance to apoptosis in drug resistant colon cancer cells by cryptotanshinone and dihydrotanshinone, two potential MDR-reversing tanshinones. The drug resistant SW620 Ad300 cells were still sensitive to both cryptotanshinone and dihydrotanshinone in the promotion of cell death. When compared with the parental SW620 cells, the two tanshinones induced less apoptosis but more autophagy in the drug resistant cells. Further studies showed that cell viability was increased after inhibition of autophagy by siRNA interference or autophagy inhibitor. Thus, autophagy induced by the two tanshinones was pro-cell death in SW620 Ad300 cells, which could overcome resistance to apoptosis. / In addition, suppression of apoptosis can be caused by p53 defects/mutations, which were found in more than 50% of all human cancers. Our results also showed that apoptosis and autophagy induced by cryptotanshinone and dihydrotanshinone were independent of the status of p53 in colon cancer cells. The p53-independent cytotoxic actions of the two tanshinones could be useful in overcoming resistance to apoptosis in cancer cells caused by p53 defects/mutations. / Taken together, the current findings indicate a great potential of cryptotanshinone and dihydrotanshinone in the reversal of MDR caused by P-gp overexpression and suppression of apoptosis. They are promising candidates to be further developed as therapeutic agents in the adjuvant therapy for colon cancer, especially for the multidrug resistant cancer types. / 結腸癌是指形成在結腸組織的惡性腫瘤，在香港常見的癌症中排第一位，亦是香港排第二位的致死癌症。結腸癌的標準治療方案主要包括手術和化療。然而，多藥耐藥是結腸癌成功化療的一個障礙。事實上，大多數癌症引起的死亡都和在癌症的發展和化療的過程中產生的多藥耐藥有關。因此，多藥耐藥的逆轉對於結腸癌的成功化療非常重要。本研究旨在通過針對多藥耐藥兩種常見的機制ABC跨膜蛋白的過表達和抑制的細胞凋亡來探討丹參酮對結腸癌細胞多藥耐藥的逆轉。 / P-gp的過表達可介導藥物排出癌細胞，從而導致多藥耐藥和化療失敗。本研究評價了tanshinone I，tanshinone IIA，cryptotanshinone，dihydrotanshinone和miltirone對P-gp介導的結腸癌細胞多藥耐藥的逆轉。雙向轉運實驗表明，只有cryptotanshinone和dihydrotanshinone可以減少P-gp介導的digoxin外排。這兩個丹參酮可以增加doxorubicin和irinotecan在P-gp過表達的結腸癌SW620 Ad300細胞中的毒性。此外，這兩個丹參酮也增加P-gp底物在SW620 Ad300細胞內的積累，推測是通過下調P-gp的mRNA和蛋白水平，以及抑制P-gp的ATP酶活性。 / 抑制的細胞凋亡可導致腫瘤細胞對促凋亡的抗癌藥物产生多藥耐藥。因此，本研究也探討了cryptotanshinone和dihydrotanshinone能否克服結腸癌細胞的凋亡耐受。結果表明cryptotanshinone和dihydrotanshinone仍然能够杀死耐藥的SW620 Ad300細胞。當與SW620細胞相比，這兩個丹參酮在耐藥細胞中誘導的細胞凋亡較少，但自噬增多。進一步研究表明，這兩個丹參酮誘導的自噬是促進細胞死亡的，從而可以克服細胞的凋亡耐受。 / 此外，p53的缺陷/突變存在於50%以上的人類癌症中，并可以抑制細胞產生凋亡。結果表明，cryptotanshinone和dihydrotanshinone誘導的凋亡和自噬與p53在結腸癌細胞中的表達無關。這兩個丹參酮不依賴於p53的細胞毒性可以用於克服p53缺陷/突變引起的凋亡耐受。 / 綜上所述，本研究結果表明cryptotanshinone和dihydrotanshinone在逆轉P-gp的過表達和抑制的細胞凋亡引起的多藥耐藥中具有巨大潛力。它們可以進一步發展為有前途的治療劑并用於結腸癌的輔助治療，尤其是用於多藥耐藥的結腸癌。 / Hu, Tao. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 163-182). / Abstracts also in Chinese. / Title from PDF title page (viewed on 06, December, 2016). / Hu, Tao. / 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.

He, Jun. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 136-156). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

越來越多證據表明了煙酰胺腺嘌呤核苷酸磷酸（nicotinamide adenine dinucleotide phosphate, NADPH）代謝對腫瘤細胞增殖和生存的重要性。最近一項研究證實了一個p53調節基因，TP53誘導的糖酵解和凋亡調節因數（TP53-inducible glycolysis and apoptosis regulator, TIGAR），在抑制凋亡和誘導NADPH產生方面的作用。抗凋亡蛋白B細胞淋巴瘤2（B-cell lymphoma 2, Bcl-2）之前被報導能夠通過還未確定的機制誘導NADPH的產生。在這篇論文研究中，我們假設Bcl-2與TIGAR耦合從而調節NADPH的產生和細胞生存，並且TIGAR可能成為一個促進細胞生長的新生存因數。這篇論文研究的目的是：1）檢測在NADPH代謝中Bcl-2與TIGAR間的生物聯繫；2）探究在哺乳動物系統中TIGAR調節的分子機制；3）研究TIGAR在體外和體內調節正常及腫瘤細胞生存的作用。 / 這篇論文的第一部分結果顯示在正常小鼠胚胎成纖維細胞（MEFs）和缺少功能性p53的人非小細胞肺癌（NSCLC）細胞中存在Bcl-2/TIGAR/NADPH這樣一個新的信號通路軸，重要抗凋亡蛋白Bcl-2與TIGAR耦合後，以一個特有並持久的方式調節NADPH代謝和細胞生長。用特異的小干擾RNA（siRNA）靶向抑制Bcl-2能夠在NSCLC細胞中抑制TIGAR/NADPH/生長信號軸。用小分子抑制劑ABT-737對Bcl-2進行藥理學抑制也能夠顯示相似的作用，而這個作用能夠通過過表達TIGAR被部分逆轉。而且，敲除TIGAR能夠降低Bcl-2誘導的NADPH產生和細胞生長，表明了TIGAR在介導TIGAR/NADPH/生長信號軸中的關鍵作用。 / 為了第二個目的，我們研究了Bcl-2對TIGAR的機制調節。我們發現過表達Bcl-2不能改變TIGAR的mRNA水平，但是能誘導轉錄後的TIGAR蛋白累積。有趣的是，TIGAR似乎能通過一個正反饋回路誘導Bcl-2的表達，這進一步促進了由Bcl-2誘導的TIGAR表達上調。除了Bcl-2，許多致癌基因或生長調節因數也被證實參與了TIGAR的調節，包括信號轉導和轉錄啟動因數3（signal transducer and activator of transcription 3, STAT3, Bcl-2的上有調節因數），表皮生長因數受體（epidermal growth factor receptor, EGFR）和肝細胞生長因數受體（hepatocyte growth factor receptor, c-Met）。 / 這篇論文的第三部分證實了TIGAR在缺少功能性p53細胞模型中的致癌作用。TIGAR過表達能夠誘導一些癌症的標誌性特徵，包括細胞代謝調節異常，細胞生長增加和凋亡減少。重要的是，TIGAR的過表達在MEFs和缺少功能性p53的NSCLC細胞中直接促成了腫瘤形成，促進了腫瘤的生長。但是功能性p53的存在無論在體外還是體內都能夠消除TIGAR這種生長促進和成瘤的作用。這些發現表明當p53功能消失時TIGAR能成為一個致癌基因，促進腫瘤形成。 / 總的來說，我們發現了在腫瘤中Bcl-2/TIGAR/NADPH這樣一條新的信號通路。Bcl-2通過增加TIGAR蛋白累積的轉錄後機制調節TIGAR。我們也證實了TIGAR受到多種致癌基因或生長調節因數的調節，包括STAT3，EGFR和c-Met。並且，我們闡明了當p53功能消失時TIGAR能成為一個致癌基因，促進細胞轉化和腫瘤形成。 / Emerging evidences reveal the importance of nicotinamide adenine dinucleotide phosphate (NADPH) metabolism for cancer cell proliferation and survival. A recent study demonstrated the role of a p53-regulated gene, TP53-inducible glycolysis and apoptosis regulator (TIGAR), in inhibiting apoptosis and inducing NADPH production. The anti-apoptotic protein B-cell lymphoma 2 (Bcl-2) has previously been reported to induce NADPH generation through undefined mechanism. In this thesis study, we hypothesized that Bcl-2 is coupled to TIGAR for regulation of NADPH production and cell survival, and that TIGAR may serve as a novel survival factor contributing to cell growth. The objectives of the thesis study are: 1) to examine the biologic relationship between Bcl-2 and TIGAR in NADPH metabolism; 2) to investigate the molecular mechanisms of TIGAR regulation in mammalian systems; and 3) to examine the role of TIGAR in regulating normal and cancer cell survival in vitro and in vivo. / Findings in first part of the thesis revealed a novel signaling axis of Bcl-2/TIGAR/NADPH in normal mouse embryonic fibroblasts (MEFs) and human non-small cell lung cancer (NSCLC) cells lacking functional p53, coupling the major anti-apoptotic protein Bcl-2 to TIGAR regulation for NADPH metabolism and cell growth in a specific and sustained manner. Targeting of Bcl-2 by specific siRNA inhibited TIGAR/NADPH/growth axis in NSCLC cells. Pharmacologic inhibition of Bcl-2 by small molecule inhibitor ABT-737 also exhibited similar effects, which was partially reversed by the overexpression of TIGAR. In addition, TIGAR knockdown reduced Bcl-2-induced NADPH production and cell growth, implicating a critical role of TIGAR in mediating Bcl-2/NADPH/growth signaling axis. / For the second objective, we studied the mechanistic regulation of TIGAR by Bcl-2. We found that overexpression of Bcl-2 did not alter TIGAR mRNA expression but induced TIGAR protein accumulation post-transcriptionally. Interestingly, TIGAR seemed to induce Bcl-2 expression via a positive feedback loop, which may further contribute to the upregulation of TIGAR expression induced by Bcl-2. In addition to Bcl-2, a number of oncogene/growth regulators were demonstrated to be involved in TIGAR regulation, including signal transducer and activator of transcription 3 (STAT3, an upstream regulator of Bcl-2), epidermal growth factor receptor (EGFR) and hepatocyte growth factor receptor (c-Met). / The third part of the thesis demonstrated the oncogenic role of TIGAR in cell models lacking functional p53. TIGAR overexpression induced several hallmark features of cancer including deregulated cell metabolism, increased cell growth and inhibited apoptosis. Strikingly, overexpression of TIGAR directly drove tumor formation and promoted tumor growth in MEFs and NSCLC cells lacking functional p53. The growth stimulatory and tumorigenic activities of TIGAR were abolished in the presence of functional p53 both in vitro and in vivo. These findings revealed TIGAR as an oncogene capable of driving tumorigenesis when p53 function is lost. / In summary, we have identified a novel signaling pathway of Bcl-2/TIGAR/NADPH in cancer. TIGAR is regulated by Bcl-2 via a post-transcriptional mechanism by enhancing TIGAR protein accumulation. We also demonstrated the regulation of TIGAR by multiple oncogene/growth regulators including STAT3, EGFR and c-Met. Furthermore, we have demonstrated TIGAR as an oncogene capable of driving cell transformation and tumorigenesis when p53 function is lost. / 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. / Lam, Kai Yee. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 158-176). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstract --- p.i / 摘要 --- p.iv / Declaration --- p.vi / Acknowledgements --- p.vii / Publications --- p.viii / Table of Content --- p.ix / List of Illustrations --- p.xii / List of Abbreviations --- p.xv / Chapter Chapter 1: --- Introduction / Chapter 1.1 --- Overview of tumor metabolism --- p.1 / Chapter 1.1.1 --- Glucose metabolism --- p.4 / Chapter 1.1.2 --- Glutamine metabolism --- p.6 / Chapter 1.1.3 --- De novo fatty acid synthesis --- p.7 / Chapter 1.1.4 --- Advantages of metabolic reprogramming in tumor cells --- p.8 / Chapter 1.2 --- Mechanisms regulating metabolic reprogramming in cancers --- p.11 / Chapter 1.2.1 --- Tumor suppressor p53 --- p.11 / Chapter 1.2.2 --- Hypoxia-inducible factor 1 (HIF-1) --- p.13 / Chapter 1.2.3 --- PI3K/Akt/mTOR signaling pathway --- p.15 / Chapter 1.2.4 --- Oncogenic Myc --- p.16 / Chapter 1.2.5 --- Oncogenic Ras --- p.18 / Chapter 1.3 --- TP53-Inducible Glycolysis and Apoptosis Regulator (TIGAR) --- p.22 / Chapter 1.3.1 --- TIGAR and oxidative stress --- p.25 / Chapter 1.3.2 --- TIGAR and carcinogenesis --- p.29 / Chapter 1.3.3 --- TIGAR and other diseases --- p.32 / Chapter 1.4 --- Hypotheses and Aims --- p.36 / Chapter Chapter 2: --- Materials and Methods / Chapter 2.1 --- Materials --- p.38 / Chapter 2.1.1 --- Chemicals and reagents --- p.38 / Chapter 2.1.2 --- Drugs --- p.41 / Chapter 2.1.3 --- Commercial detection kits --- p.41 / Chapter 2.1.4 --- Antibodies --- p.42 / Chapter 2.2 --- Cell culture --- p.43 / Chapter 2.3 --- Plasmids --- p.44 / Chapter 2.4 --- Transfection --- p.46 / Chapter 2.5 --- Retrovirus infection --- p.47 / Chapter 2.6 --- Drug treatment --- p.47 / Chapter 2.7 --- Cell viability assay --- p.48 / Chapter 2.8 --- Trypan blue exclusion assay --- p.49 / Chapter 2.9 --- NADPH assay --- p.49 / Chapter 2.10 --- Cell death detection ELISA --- p.50 / Chapter 2.11 --- Western blotting --- p.50 / Chapter 2.12 --- Reverse TranscriptionPolymerase Chain Reaction (RT-PCR) --- p.51 / Chapter 2.13 --- Cell cycle analysis --- p.52 / Chapter 2.14 --- Transwell migration and matrigel invasion assays --- p.53 / Chapter 2.15 --- In vivo studies --- p.54 / Chapter 2.16 --- Histology and immunohistochemistry --- p.55 / Chapter 2.17 --- Statistical analysis --- p.56 / Chapter Chapter 3: --- Indentification of Novel Bcl-2/TIGAR/NADPH Signaling Axis / Chapter 3.1 --- Introduction --- p.57 / Chapter 3.2 --- Results --- p.60 / Chapter 3.2.1 --- Bcl-2-induced NADPH production and cell growth is associated with TIGAR upregulation in p53-null MEFs --- p.60 / Chapter 3.2.2 --- Identification of Bcl-2/TIGAR/NADPH signaling axis in p53-negative NSCLC cells --- p.63 / Chapter 3.2.3 --- Bcl-2 targeting reduces TIGAR expression and NADPH production in MEFs and NSCLC cells --- p.66 / Chapter 3.2.4 --- Pharmacologic intervention of Bcl-2 alters TIGAR levels in MEFs and NSCLC cells --- p.71 / Chapter 3.2.5 --- Bcl-2 targeting inhibits TIGAR expression, NADPH production and cell growth in Bcl-2-amplified small cell lung cancer (SCLC) cells --- p.76 / Chapter 3.2.6 --- Bcl-2-induced TIGAR expression is highly specific compared to other pro-survival proteins --- p.78 / Chapter 3.2.7 --- Bcl-2/TIGAR/NADPH signaling axis is functionally intact in p53-positive NSCLC cells --- p.80 / Chapter 3.3 --- Discussion --- p.83 / Chapter Chapter 4: --- Mechanisms of TIGAR Regulation / Chapter 4.1 --- Introduction --- p.88 / Chapter 4.2 --- Results --- p.90 / Chapter 4.2.1 --- Bcl-2 regulates TIGAR by post-transcriptional mechanism --- p.90 / Chapter 4.2.2 --- Bcl-2-induced TIGAR expression is associated with upregulation of other pro-survival proteins --- p.94 / Chapter 4.2.3 --- STAT3 activation can serve as a biological signal for TIGAR induction --- p.97 / Chapter 4.2.4 --- Tyrosine kinase receptors contributes to TIGAR regulation --- p.100 / Chapter 4.2.5 --- The existence of TIGAR/Bcl-2 positive feedback loop --- p.102 / Chapter 4.3 --- Discussion --- p.104 / Chapter Chapter 5: --- TIGAR is Oncogenic / Chapter 5.1 --- Introduction --- p.107 / Chapter 5.2 --- Results --- p.109 / Chapter 5.2.1 --- Overexpression of TIGAR alters several hallmark features of cancer --- p.109 / Chapter 5.2.2 --- TIGAR drives tumor formation in vivo --- p.114 / Chapter 5.2.3 --- Tumorigenic activity of TIGAR is functionally counteracted by functional p53 --- p.123 / Chapter 5.3 --- Discussion --- p.134 / Chapter Chapter 6: --- Summary --- p.138 / Chapter Chapter 7: --- Future Prospective --- p.143 / Appendices --- p.148 / References --- p.158

Background & Aims: By whole genome sequencing, we identified for the first time that solute carrier family 12 member 5 (SLC12A5) gene located on chromosome 20q13.12 was amplified in colorectal cancer (CRC). We aimed to determine the amplification status of SLC12A5 and its clinical implication in CRC, and characterize the functional mechanisms of SLC12A5 in colorectal carcinogenesis. / Materials and Methods: Protein expression level of SLC12A5 was evaluated by immunohistochemistry. SLC12A5 amplification was verified by fluorescence in situ hybridization (FISH). The correlations between SLC12A5 expression and clinicopathologic parameters as well as the prognosis impact of SLC12A5 were analyzed in 195 CRC patients. The biological function of SLC12A5 in CRC cell lines were determined by cell viability, colony formation, invasion, migration, flow cytometry and in vivo tumorigenicity assays. Standard tail vein metastatic assay was performed to examine the effect of SLC12A5 in lung metastasis in nude mice. Western blot, luciferase reporter assays and human tumor metastasis PCR array were performed to evaluate SLC12A5 downstream effectors and related pathways. / Results: RT-PCR showed SLC12A5 was readily expressed in 7 of 9 CRC cell lines, but was absent in normal colorectal tissues. The mean protein expression level of SLC12A5 was significantly higher in primary CRCs as compared to their adjacent normal tissues. Amplification of SLC12A5 was detected in 40.8% (78/191) of primary CRCs by FISH, which was positively correlated with its protein overexpression (P < 0.001). Overexpression of SLC12A5 was positively associated with a more advanced TNM stage (P < 0.05). Multivariate Cox regression analysis showed that SLC12A5 overexpression was an independent predictor of poorer survival of CRC patients (P = 0.018). We further tested the biological function of SLC12A5 in human colon cancer cells. Ectopic expression of SLC12A5 in colon cancer cells SW480 and SW1116 increased proliferation and colony formation. Silencing SLC12A5 expression in HCT116 by siRNA had the opposite effects in vitro, and knockdown of SLC12A5 by shRNA significantly inhibited xenograft tumor growth in nude mice. We further revealed that SLC12A5 inhibited apoptosis of colon cancer cells by mediating apoptosis-inducing factor (AIF) and endonuclease G (EndoG) -dependent apoptotic signaling pathway. Moreover, gain-and loss-of-function experiments showed that SLC12A5 enhanced cell invasion and migration in vitro. Knockdown of SLC12A5 by shRNA significantly inhibited lung metastasis in nude mice. SLC12A5 promoted tumor metastasis through regulating key elements of the matrix architecture, such as matrix metallopeptidase and fibronectin. / Conclusion: We have identified a novel amplification gene SLC12A5 which is overexpressed in CRC. SLC12A5 may be an independent prognostic marker for CRC and may play a pivotal oncogenic role in colorectal carcinogenesis by inhibiting apoptosis and promoting metastasis. / 背景和目的：通過對結直腸癌進行全基因組測序，我們首次發現位於染色體20q13.12的SLC12A5基因在結直腸中擴增。本研究旨在探索SLC12A5在結直腸癌中的擴增情況和臨床意義，并進一步研究SLC12A5在結直腸癌發生發展中的作用機制。 / 材料和方法：採用免疫组化方法檢測SLC12A5的蛋白表达水平。應用熒光原位雜交方法驗證SLC12A5基因的擴增情況。在195例結直腸癌患者中对SLC12A5表达與临床病理關係及其對預後的影響其进行分析。通过檢測細胞活力、細胞集落形成實驗、侵襲實驗、遷移實驗、流式細胞術和體內成瘤實驗以研究SLC12A5在結直腸癌中的生物学功能。進而通過免疫印跡、熒光素酶報告實驗和人腫瘤轉移的PCR陣列，探索SLC12A5調控的基因和相关途径。 / 结果：我們採用RT-PCR方法檢測SLC12A5在9株結直腸癌細胞株的表達情況，SLC12A5在7株結直腸癌細胞株中穩定表達，但是在正常大腸組織中表達沉默。SLC12A5在結直腸中的平均蛋白表達水平顯著高於其鄰近的正常組織。通過熒光原位雜交方法，在40.8% （78/ 191）的結直腸癌中檢測到SLC12A5的擴增，該基因的擴增與其蛋白高表達水平呈正相關關係。SLC12A5高表達水平跟晚期TNM分期密切相關（P <0.05）。多因素Cox回歸分析表明，SLC12A5高表達是結直腸癌患者較差的生存的獨立預測因子（P = 0.018）。我們進一步在人結腸癌細胞株中檢測SLC12A5的生物功能。在結腸癌細胞SW480和SW1116中過度表達SLC12A5促進細胞增殖和集落形成。siRNA敲低HCT116 細胞SLC12A5的表達在體外實驗中有相反的效果。此外，shRNA敲低SLC12A5的表達顯著抑制裸鼠移植瘤的生長。我們進一步發現，SLC12A5通過介導凋亡誘導因子（AIF）和核酸內切酶G（EndoG）-依賴的細胞凋亡信號轉導通路抑制結腸癌細胞的凋亡。此外，功能獲得性和功能缺失性的體外實驗表明，SLC12A5促進腫瘤細胞的侵襲和遷移。尾靜脈注射實驗表明shRNA敲低SLC12A5的表達顯著抑制裸鼠肺轉移。SLC12A5通過調節基質結構的關鍵因子，如基質金屬蛋白酶和纖維連接蛋白，促進腫瘤轉移。 / 结论：我們發現了一個新的擴增基因SLC12A5，該基因在結直腸癌中高表達。SLC12A5是結直腸癌的一個獨立的預後標誌物。SLC12A5通過抑制細胞凋亡和促進腫瘤轉移，在結直腸癌的發生發展中起了舉足輕重的致癌作用。 / Xu, Lixia. / Thesis Ph.D. Chinese University of Hong Kong 2014. / Includes bibliographical references (leaves 107-120). / Abstracts also in Chinese. / Title from PDF title page (viewed on 05, October, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

Bibliography: leaves 150-166. / ix, 166, xxii leaves : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / To assess the role of acetylator status and glutathione S-transferase[mu] (GST[mu]) null phenotype on the risk for development of colorectal neoplasms in humans and to determine whether this was influenced by the dietary intake of meat. / Thesis (M.D.)--University of Adelaide, Dept. of Medicine, 1995?

Colorectal cancer (CRC) is a major problem in affluent countries worldwide. In Australia it is the second most commonly diagnosed malignancy with approximately 13,000 new cases diagnosed each year. This disease is also the leading cause of cancer related death in Australia with approximately 4,500 fatalities each year. Epidemiological studies have shown geographical variation in the incidence of disease, with diet considered to be a key contributing factor to CRC risk. In particular, diets high in fibre and low in fat have been demonstrated to reduce the risk of developing CRC. Fibre is heterogeneous in nature and can be categorised into different subtypes. Resistant starch is a component of fibre which remains largely intact throughout the gastrointestinal tract until it reaches the colon. Here it undergoes bacterial fermentation to produce the short chain fatty acids (SCFAs) acetate, propionate and butyrate (BuA). Each of the SCFAs are bioactive in the colon, with the most active being BuA. The beneficial effects of fibre have been linked to BuA’s ability to induce colon cancer cell differentiation, reduce proliferation and initiate apoptosis. Interestingly, in normal cells BuA is utilised as the preferential energy source and has been shown to promote proliferation. With an apparent “paradoxical effect” on normal and cancerous cells BuA has been the subject of much investigation as a potential anticancer agent. Despite numerous studies investigating BuA actions, the exact biological mechanisms remain largely undefined. This thesis explored a possible mechanism for BuA-induced apoptosis and inhibition of proliferation. In 2003, two publications provided evidence that SCFAs, including BuA, were ligands to two members of a previously orphan family of G-protein coupled receptors (GPCRs); GPCR41 and 43. Of the two receptors BuA had the strongest effect on GPCR43. Consequently this thesis investigated the possibility that BuA acts to decrease CRC proliferation and induce apoptosis by binding to and activating GPCR43 on CRC cells. It was hypothesised that GPCR43 acted as a “BuA sensor” on the surface of the cell to mediate the effects of BuA. This experimental work utilised PCR, Q-PCR, measures of apoptosis, proliferation and differentiation and RNAi knockdown. The key areas of investigation included: (1) Determining if GPCR43 was present on a range of CRC cell lines with a cell line to represent adenocarcinoma, carcinoma and metastatic stage of disease. (2) Investigating the expression of GPCR43 with manipulated nutrient media and different levels of cell confluence. (3) Exploring GPCR43 expression in normal and malignant human patient biopsies. (4) Determining if the inhibition of G-protein function using inhibitors influenced BuAinduced changes to apoptosis and proliferation. (5) Using RNAi, investigating the effect that GPCR43 knockdown would have on BuA-induced changes to proliferation and apoptosis. The key findings from this work included: (1) Presence of GPCR43 on some but not all CRC cell lines. (2) Modulation of GPCR43 expression with exposure to BuA and altered glucose concentrations in the media. (3) An influence of G-protein inhibition on BuA-induced apoptosis but not proliferation in some cell lines. (4) GPCR43 knockdown using RNAi indicated that GPCR43 is not exclusively required for BuA to regulate apoptosis and proliferation. The results from this work indicate that GPCR43 is not likely to exclusively mediate BuA’s effects, but opens up new areas of research into the exact role of GPCR43 on CRC cells. / Thesis (Ph.D.) - University of Adelaide, School of Molecular and Biomedical Science, 2008

Graduation date: 2006

published_or_final_version / Pathology / Doctoral / Doctor of Philosophy