published_or_final_version / Surgery / Master / Master of Philosophy

published_or_final_version / Surgery / Master / Master of Philosophy

Not available / text

Not available / text

A description of two techniques used extensively in this study namely cell counting with a "cell counting plate" and argentation TLC for the separation of ω -6 -fatty acids is given. Zn supplementation into GM of two malignant (BL-6 and Hep- 350) and a non-malignant (LLC-MK) cell line/s resulted in an increased uptake of Zn by the cells and progressively suppressed proliferation of particularly the malignant cells. Zn chelation by EDTA suppressed in vitro proliferation of all 3 cell line, this effect being more pronounced in the malignant cells. A dietary Zn deficiency resulted in alopecia in mice and both a dietary Zn deficiency and Zn excess reduced growth of BL-6 tumours implanted subcutaneously in mice. Zn supplementation into GM progressively increased the uptake of [1-¹⁴C]-LA by BL-6 and LLC-MK cells but had a very slight though irregular effect on this parameter in the Hep- 350 cells. Zn supplementation also stimulated desaturase activity in the BL-6 cells. These results suggested that there are select cell lines whose Δ⁶-desaturase activity responds positively to Zn supplementation (e.g. the BL-6 cells). Delta-6-desaturase activity was also assayed in microsome preparations from different tissues. No enzyme activity was detected in the microsomes prepared from the BL-6 tumours. There was no significant effect with the addition of Zn or EDTA, on Δ⁶-desaturase activity of the regenerating liver microsomes. In the resting liver microsomes this enzyme activity was reduced only when EDTA and Zn were added together and when EDTA was added to the reaction medium as well as to the microsome preparations 2 hr before the enzyme activity assay was initiated. The results of these experiments suggested that the Δ⁶-desaturase enzyme in the microsome preparations may have had an adequate amount of Zn with further additions having no stimulatory effect on the enzyme. Two independent mechanisms of control of cell proliferation by low and high Zn are suggested to operate.

Anti-oestrogens act via the oestrogen receptor whether they compete with the hormone for binding to the receptor and therefore interfere with DNA binding or inhibit transcriptional activity. These receptors exist as a large 85 complex and/or a small 45 form on sucrose density gradients. High performance ion-exchange chromatography has confirmed that the oestrogen and progestin complex is present in various isoforms. Progestin receptor heterogeneity could be influenced by the presence of oestrogens and anti-oestrogens in the culture media of hormone-dependent neoplastic cells. Cell culture methods offer the opportunity to test effects of specified components in repeated experiments on a homogeneous population of cells. MCF-7 and T47-D human breast cancer cell lines were conditioned to grow in a serum-free environment. There was no difference in cell proliferation rates, nor in their oestrogen or progestin receptor levels when compared to the same cells grown in conventional media. Receptors were present mainly in the large molecular 85 form. Both the MCF-7 and T47-D breast cancer cells showed an increase in proliferation rate with the addition of oestrogen or diethylstilbestrol. There was a corresponding loss of progestin receptor levels and an alteration in the high performance ion-exchange isoforms. Flow cytometry confirmed differences in the S-phase components of the cells following exposure to oestrogens. The proliferation rates of the cell lines as well as their progestin receptor levels decreased when treated with tamoxifen or the hydroxylated tamoxifen. There were marked changes on high performance ion-exchange chromatography profiles. DNA ploidy and S-phase showed signs of toxicity and there was an increase in cellular debris. The MCF-7 and T47-D human breast cancer cell line retained response to antioestrogen saturation.

The glycoprotein stanniocalcin-1 (STC1) is a paracrine factor in mammals which plays roles in various (patho)physiological functions, such as inflammation and carcinogenesis. Considerable numbers of studies showed dysregulation of STC1 expression in different types of human cancers. A previous study from our group, using clinicopathological data of 216 hepatocellular carcinoma (HCC) patients revealed greater STC1 gene expression in tumors than the paired normal samples. However, patient samples with greater STC1 level exhibited smaller tumor size. In fact, multiple cell types, growth factors and matrix components in tumor microenvironment (TME) control cancer progression. Emerging evidence support the important role of infiltrating immune cells on tumor progression. Among those, tumor associated macrophages (TAM) in TME is known to be an essential driver of tumor inflammation and progression, exerting a yin-yang influence to determine if the tumor is suppressed or paving the way to metastasize. Hepatocellular carcinoma (HCC) is mainly caused by chronic inflammation. With hindsight, the roles of STC1 in inflammation and carcinogenesis were documented. However, the observation on the negative correlation of STC1 expression with tumor size in HCC patients and the roles of STC1 on the interactions between tumor cells and macrophages are not clear. In Chapter 2, the inverse correlation of STC1 expression with tumor size was addressed. Human metastatic HCC cell line, MHCC97L which was stably transfected with empty vector (P) and STC1 (S1) were used. Nude mice xenograft model showed that tumor size and volume formed from S1 cells were significantly smaller than that from P cells. The observation agreed with the clinical data aforementioned. In vitro studies demonstrated S1 cells had lower plating efficiency, migratory and proliferative potential, illustrating a lower tumorigenicity. Biochemical analyses on the rate of glycolysis, extracellular O2 consumption, ATP production and Western blot studies on mTOR/p70S6K/rpS6 pathway showed the S1 cells adopted a lower energy metabolism. The data may explain the negative correlation between STC expression level and tumor size. In cancer microenvironment, infiltration of host immune cells, especially macrophages, contributes to inflammation and tumor progression. In Chapter 3, it was hypothesized that cancer cell-derived STC1 alter macrophage functions. Therefore, the effects of STC1-overexpressing MHCC97L on macrophages were studied. To mimic their interactions, Boyden chamber insert model was adopted to co-culture MHCC97L (97L/P and 97L/S1) and THP-1. Our data illustrated 97L/S1 suppressed migratory response of THP-1, with or without the addition of monocyte chemoattractant protein 1 (MCP-1) as the chemoattractant. Quantitative PCR showed downregulation of cytokine/chemokine receptors (CCR2, CCR4, CSF-1R) in THP-1 when co-cultured with 97L/S1. This prompted us to study the alterations of pathways related to cell motility in THP-1 by 97L/S1. Transcriptomic analysis detected 1784 differentially expressed genes (DEGs) between THP-1 cells co-cultured with 97L/P and 97L/S1. Ingenuity Pathway Analysis (IPA) prioritized an inhibition of RhoA signaling, which is known to stimulate cell motility. Western blotting analysis supported the IPA prediction and the cell migration data to show a significant reduction of MLC2 phosphorylation, leading to impaired formation of stress fibers, cell contraction and cell motility. The preceding chapters focused on cancer cell-derived STC1 on HCC cells or THP-1 derived macrophages. In Chapter 4, it was hypothesized that macrophage-derived STC1 may also play a role in macrophage differentiation and inflammation, which modulate tumorigenicity of HCC during macrophage-cancer cell interactions. Thus, the roles of endogenous STC1 in macrophage differentiation and functions were investigated. Using human leukemia monocytic cell line THP-1, a pilot study showed a treatment with phorbol 12-myristate 13-acetate (PMA) significantly upregulated STC1 expression and pro-inflammatory cytokines. In follow-up studies, THP-1 was pharmacologically stimulated to differentiate into (i) classically activated macrophages (CAM)/ M1 state, and (ii) alternatively activated macrophages (AAM)/ M2 state. Greater STC1 expression was found to be associated with CAM. To examine the role of STC1 in CAM, siRNASTC1 was used for gene knockdown. Conditioned medium collected from siRNASTC1-treated CAM inhibited migration of HCC cell line Hep3B. Transcriptomic analysis of siRNASTC1-treated CAM revealed an upregulation on TBC1D3G gene, which is involved in the release of extracellular vesicles (EVs) in macrophage to mediate inflammation. This study demonstrated the association between STC1 and macrophage-mediated inflammation. Collectively, the above studies elucidated the influence of STC1 on cancer cell metabolism, macrophage differentiation and function. It warrants further investigations to unravel the therapeutic potential of STC1 in inflammation and carcinogenesis.

published_or_final_version / abstract / Anatomy / Doctoral / Doctor of Philosophy

Ho, Tik Shun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 88-102). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.vii / Table of Contents --- p.viii / List of Table --- p.x / List of Figures --- p.xi / List of Abbreviations --- p.xiii / Chapter CHAPTER 1 --- General Introduction --- p.1 / Chapter 1.1 --- Fatty Acid Synthase (FAS) - 7-domain multifunctional enzyme --- p.1 / Chapter 1.1.1 --- Functions --- p.1 / Chapter 1.1.2 --- Structure --- p.2 / Chapter 1.2 --- Fatty Acid biosynthesis reactions --- p.4 / Chapter 1.3 --- Malonyl Coenzyme A - An important mediator in lipogenesis --- p.7 / Chapter 1.4 --- FAS expression in different histotypes --- p.8 / Chapter 1.4.1 --- FAS in normal cells --- p.8 / Chapter 1.4.2 --- FAS in pathological cells --- p.8 / Chapter 1.4.3 --- Tumor-associated FAS (Oncogenic antigen-519) in cancer cells --- p.9 / Chapter 1.5 --- FAS signaling models in breast and prostate cancers --- p.12 / Chapter 1.5.1 --- Association between FAS and PI3K／Akt pathway --- p.12 / Chapter 1.5.2 --- Hypothetical model of FAS hyperactivity in breast and prostate cancer cells --- p.13 / Chapter 1.6 --- FAS inhibition to tackle cancer cell growth --- p.15 / Chapter 1.6.1 --- FAS inhibitors --- p.15 / Chapter 1.6.1.1 --- Cerulenin --- p.16 / Chapter 1.6.1.2 --- C75 --- p.17 / Chapter 1.6.2 --- Small interfering RNA --- p.17 / Chapter 1.7 --- FAS inhibition to enhance chemoresistant cancer cells sensitivity to drugs --- p.19 / Chapter 1.8 --- Hypothesis --- p.20 / Chapter CHAPTER 2 --- Methods and Materials --- p.21 / Chapter 2.1 --- Chemicals and antibodies --- p.21 / Chapter 2.2 --- Cell cultures --- p.21 / Chapter 2.3 --- MTT assay --- p.22 / Chapter 2.4 --- 5-Bromo-2'-deoxyuridine (BrdU)-labeling cell proliferation assay --- p.22 / Chapter 2.5 --- Cytotoxicity detection assay of LDH release --- p.23 / Chapter 2.6 --- DNA flow cytometry --- p.23 / Chapter 2.7 --- Confocal micocropy --- p.24 / Chapter 2.8 --- Immunoblot analysis --- p.24 / Chapter 2.8.1 --- Preparation of protein lysates --- p.24 / Chapter 2.8.2 --- Immunoblotting --- p.25 / Chapter 2.9 --- Caspase inhibitor studies --- p.26 / Chapter 2.10 --- Analysis of mitochondrial membrane potential --- p.26 / Chapter 2.11 --- Determination of caspase activities --- p.27 / Chapter 2.12 --- siRNA transfection --- p.27 / Chapter 2.13 --- Statistical analysis --- p.28 / Chapter CHAPTER 3 --- Results --- p.29 / Chapter 3.1 --- Cytostatic & cytotoxic studies of FAS inhibitors on human cancer cells --- p.29 / Chapter 3.1.1 --- Cerulenin and C75 suppress cell growth of different cancer histotypes --- p.29 / Chapter 3.1.2 --- Cerulenin and C75 suppress cell growth of A-375 dose- and time-dependently --- p.32 / Chapter 3.1.3 --- Cerulenin and C75 exert cytotoxic effect on A-375 but not normal skin HS68 cells --- p.36 / Chapter 3.1.4 --- Cerulenin and C75 arrest cell cycle progression and induce apoptosis with DNA Fragmentation --- p.39 / Chapter 3.2 --- Mechanistic studies of FAS inhibitors in A-375 cells --- p.46 / Chapter 3.2.1 --- Cerulenin and C75 induce caspase-dependent apoptosis --- p.46 / Chapter 3.2.2 --- Cerulenin- and C75-induced apoptosis involve extrinsic death receptor pathway --- p.52 / Chapter 3.2.3 --- Cerulenin- and C75-induced apoptosis involve intrinsic mitochondrial pathway --- p.57 / Chapter 3.2.4 --- Extrinsic death receptor pathway serves as a pioneer and links with intrinsic mitochondrial pathway in cerulenin- and C75-induced apoptosis --- p.65 / Chapter 3.3 --- Small interfering RNA on Fatty Acid Synthase (FAS siRNA) --- p.68 / Chapter 3.3.1 --- FAS siRNA induces PARP cleavage --- p.68 / Chapter 3.3.2 --- FAS siRNA triggers caspase-dependent apoptosis as FAS inhibitors --- p.70 / Chapter CHAPTER 4 --- Discussion --- p.72 / Chapter CHAPTER 5 --- Future Prospect --- p.85 / Chapter CHAPTER 6 --- References --- p.88

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20331号 / 工博第4268号 / 新制||工||1661(附属図書館) / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 北村 隆行, 教授 北條 正樹, 教授 西脇 眞二 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM