Second only to lung cancer, breast is the leading type of cancer among women in the US. Despite all the medical advances over the past few decades, toxicity and increased resistance to standard drug therapy still remains a significant problem. The heterogeneic nature of all cancers has led to a shift in treatment approaches, in that more research is being carried out with combination treatments in the hope that a multidirectional targeting of cancer will be far more effective than the current single treatment options. Our goal was to gain a better understanding of the molecular mechanisms of a nonhydrolyzable ether analog of RRR-[alpha]-tocopherol, 2, 5, 7, 8-tetramethyl-2R-(4R, 8R, 12-trimethyltridecyl)chroman-6-yloxyacetic acid (abbreviated [alpha] -TEA), and to investigate its efficacy when used in combination with known chemotherapeutics 9-nitro-camptothecin (9NC), and Paclitaxel (Taxol). The data presented here looks encouraging as it shows a clinically relevant delivery method using [alpha]-TEA and 9NC has the unique ability to reduce primary tumor burden as well as macro and micrometastatic lung and lymph node lesions in an aggressive syngeneic mouse mammary model, while displaying no obvious toxic side effects. The effect of combination treatments on tumor volume appears in part to be moderated by an increase in tumor cell apoptosis and a decrease in tumor cellular proliferation. Next, the intricate molecular mechanism of how [alpha]-TEA alone and in combination with 9NC is able to induce apoptosis in 66cl-4-GFP murine mammary cancer was investigated. The data suggest that the signaling pathway that ultimately leads to apoptosis is caspase dependent, is able to upregulate pro-death players while at the same time downregulate pro-survival proteins such as c-Flip and survivin. Finally, we investigated the efficacy of [alpha]-TEA used in an allograft mouse model following treatment with Taxol. Combination treatments were able to significantly reduce primary tumor burden, decrease lung and lymph node micrometastases, tumor cell proliferation, tumor blood vessel density as well as increase tumor cell apoptosis. Based on the results presented, we propose that [alpha]-TEA when used alone and in combination is an effective, non-toxic option for cancer treatment which warrants further investigation. / text

非傳染性疾病是目前全球最常見的疾病之一。不健康的食相信是導致非傳染性疾病增加的主要因素之一。因此，我們就食對乳腺癌的形成和膽固醇代謝調控的影響進行了研究。 / 在去除卵巢的祼鼠模型中，我們研究了長期和短期熱量限制對乳腺癌腫瘤增殖的影響。14週齡的小鼠被隨機分為5組：自由攝食組 (AL)；熱量攝入控制在AL80% 的20%CCR組；熱量攝入控制在AL的70% 的30%CCR組；熱量攝入控制在AL的65% 的35%CCR組和短期熱量限制 （SCR）組 (前3.5週熱量攝入控制在AL的65%，之後的13.5週自由攝食)。10週後，熱量限制組的腫瘤體積明顯較AL組小 (P < 0.05)。排除攝食對體重的影響，SCR組的腫瘤重量明顯較AL組小 (P < 0.05)。本實驗結果表明，在此動物模型中，短期熱量限制能有效抑制乳腺癌細胞的增殖。 / 此外，我們還研究了芹菜素在肝細胞中對膽固醇代謝的影響。芹菜素是一種常見的黃酮類化合物。研究發現，在WRL-68細胞中，芹菜素能夠劑量依賴性的抑制3 - 羥基-3 - 甲基 - 戊二酸單酰輔酶還原酶 (HMGCR)和固醇調節元件結合蛋白-2 (SREBP-2) 信使RNA和蛋白的表達及其啟動子的轉錄活性。綜上所述，在肝細胞中，芹菜素能有效抑制HMGCR和SREBP-2的表達，從而達到降低膽固醇的效果。 / 總括而言，本研究表明在去除卵巢的祼鼠模型中，短期熱量限制能有效抑制乳腺癌細胞的生長和芹菜素能有效抑制HMGCR和SREBP-2的表達。 / Non-communicable diseases (NCD) are one of the leading causes of mortality in the developed and under-developing countries. Diet is a major risk factor of NCD. In the present study, effects of diet modification on breast cancer development and cholesterol metabolism were investigated. / In the first part of this study, the effect of chronic and short-term calorie restriction (CR) on breast tumor growth in ovariectomized nude mice was investigated. The calorie-restricted dietary regimen limited the total fat intake only. 14 week-old ovariectomized female nude mice were randomly assigned to ad libitum fed (AL), 20%CCR (17-week 80% of AL), 30%CCR (17-week 70% of AL), 35%CCR (17-week 65% of AL) and short-term CR (3.5-week 65% of AL followed by 13.5-week 100% AL consumption) groups. Starting from 10 weeks after transplant of cells, the tumor volumes in all calorie-restricted groups were significantly smaller (P < 0.05) than that in ad libitum control. At sacrifice, the tumor weight in short-term CR was significantly smaller (P < 0.05) than that in ad-libitum control after normalized with body weight. This indicated that short-term CR could suppress tumor in this model. / In the second part of this study, the effect of apigenin on cholesterol metabolism was investigated. Apigenin is one of the most abundant flavonoids. In the present study, we investigated the effect of apigenin on several cholesterol-related gene expression in hepatic cells. In WRL-68 cells treated with apigenin, promoter transcription activity, mRNA and protein expression of HMGCR and SREBP-2 were significantly decreased in a dose-dependent manner. Taken together, we concluded that apigenin inhibited HMGCR and SREBP-2 gene expressions in hepatic cells, which might elicit the hypocholesterolemic effects. / In conclusion, our study has demonstrated that short-term CR could significantly block the breast tumor growth in a mice model and apigenin could inhibit the expression of HMGCR and SREBP-2 in liver cell lines. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Wong, Tsz Yan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 83-99). / Abstracts also in Chinese. / ACKNOWLEGEMENTS --- p.i / ABSTRACT --- p.ii / 摘要 --- p.iv / list of abbreviations --- p.v / list of figures --- p.vii / list of tables --- p.IX / TABLE of CONTENTS --- p.X / Chapter 1 --- CHAPTER 1 --- p.1 / General Introduction --- p.1 / Chapter 1.1 --- Calorie Restriction and the Prevention of Postmenopausal Breast Cancer --- p.2 / Chapter 1.1.1 --- Breast Cancer --- p.2 / Chapter 1.1.2 --- Epidemiology of Excess Body Weight and Cancer Risk --- p.3 / Chapter 1.1.3 --- Calorie Restriction and Cancer Prevention --- p.7 / Chapter 1.1.4 --- Mechanistic Targets of Calorie Restriction --- p.8 / Chapter 1.1.4.1 --- Effect of Calorie Restriction on Estrogen --- p.8 / Chapter 1.1.4.1 --- Effect of Calorie Restriction on Cell Cycle Regulation --- p.12 / Chapter 1.1.4.1 --- Effect of Calorie Restriction on Apoptosis --- p.14 / Chapter 1.2 --- Effect of Apigenin on Cholesterol Homeostasis --- p.17 / Chapter 1.2.1 --- Cardiovascular Disease and Blood Cholesterol --- p.17 / Chapter 1.2.2 --- Molecular Regulation of Cholesterol Metabolism --- p.21 / Chapter 1.2.2.1 --- HMG-CoA Reductase --- p.21 / Chapter 1.2.2.2 --- CYP7A1 --- p.24 / Chapter 1.2.2.3 --- Apolipoprotein A-1 --- p.26 / Chapter 1.2.2.4 --- Low Density Lipoprotein Receptor --- p.29 / Chapter 1.2.2.5 --- Sterol Regulatory Element Binding Proteins --- p.31 / Chapter 1.2.3 --- Flavonoid and its Association with Cholesterol Metabolism --- p.36 / Chapter 1.2.4 --- Apigenin: A Potential Alternative --- p.39 / Chapter 2 --- CHAPTER 2 --- p.41 / MATERIALS AND METHODS --- p.41 / Chapter 2.1 --- Chemicals and Materials --- p.41 / Chapter 2.1.1 --- Chemicals --- p.41 / Chapter 2.1.2 --- Plasmids --- p.41 / Chapter 2.2 --- Cell Culture --- p.41 / Chapter 2.2.1 --- Maintainance of Cells --- p.41 / Chapter 2.2.2 --- Preparation of Cell Stock --- p.42 / Chapter 2.2.3 --- Cell Recovery from Liquid Nitrogen Stock --- p.42 / Chapter 2.3 --- Measurement of Cell viability --- p.43 / Chapter 2.4 --- Semi-Quantitative and Quantitative RT-PCR Assay --- p.43 / Chapter 2.4.1 --- RNA Isolation and cDNA Synthesis --- p.43 / Chapter 2.4.2 --- Quantitative Real Time PCR Assay --- p.43 / Chapter 2.4.2.1 --- Real Time PCR Using TaqMan Probe --- p.43 / Chapter 2.4.2.2 --- Real Time PCR Using SYBR Green Dye --- p.44 / Chapter 2.4.2.3 --- Statistical Analysis of 2⁻ΔΔ{U+A7F0}{U+1D40} Comparative Gene Expression --- p.44 / Chapter 2.5 --- Western Blot Analysis --- p.46 / Chapter 2.6 --- Measurement of Promoter Activity --- p.46 / Chapter 2.6.1 --- Plasmid Preparation --- p.46 / Chapter 2.6.2 --- Transient Transfection and Dual-Luciferase Assay --- p.47 / Chapter 2.7 --- Animal Experiment Design --- p.47 / Chapter 2.7.1 --- Animal Model and Dietary Regimens --- p.47 / Chapter 2.7.2 --- Tissue Sample Collection --- p.50 / Chapter 2.7.3 --- Plasma Estradiol Determination --- p.50 / Chapter 2.7.4 --- Protein and RNA extraction --- p.50 / Chapter 2.8 --- Statistical Analysis --- p.50 / Chapter 3 --- Chapter 3 --- p.51 / EFFECT OF CHRONIC AND short-term calorie restriction on breast tumor growth in ovariectomized nude mice --- p.51 / Chapter 3.1 --- Introduction --- p.51 / Chapter 3.2 --- Objectives --- p.52 / Chapter 3.3 --- Results --- p.53 / Chapter 3.3.1 --- Food Intakes, Body, Liver and Uterus Wet Weights of the Mice --- p.53 / Chapter 3.3.2 --- Tumor Development --- p.57 / Chapter 3.3.3 --- Plasma Estradiol Level --- p.62 / Chapter 3.3.4 --- Estradiol Responsive Gene expression in Tumors --- p.63 / Chapter 3.3.5 --- Cell Apoptotic and Cell Cycle-Regulated Protein expression in Tumors --- p.65 / Chapter 3.4 --- Discussion --- p.67 / Chapter 4 --- CHAPTER 4 --- p.69 / Apigenin inhibits the expression of hmg-coa reductase and srebp-2 in hepatic cells --- p.69 / Chapter 4.1 --- Introduction --- p.69 / Chapter 4.2 --- Objectives --- p.70 / Chapter 4.3 --- Results --- p.70 / Chapter 4.3.1 --- Effect of Apigenin on Cell Viability --- p.70 / Chapter 4.3.2 --- Effect of Apigenin on HMGCR, CYP7A1, LDLR, ApoA-1, SREBP-1 and SREBP-2 mRNA expressions --- p.72 / Chapter 4.3.3 --- Effect of Apigenin on HMGCR, LDLR, ApoA-1 and SREBP-2 Promoter Transcription Activity --- p.75 / Chapter 4.3.4 --- Effect of Apigenin on HMGCR, SREBP-1 and SREBP-2 Protein Expression --- p.77 / Chapter 4.3.5 --- Role of Estrogen Receptor in Apigenin induced SREBP-2 Inhibition --- p.79 / Chapter 4.4 --- Discussion --- p.80 / Chapter 5 --- CHAPTER 5 --- p.82 / SUMMARY --- p.82 / References --- p.83