Lam Sze Kwan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 172-200). / Abstracts in English and Chinese. / Acknowledgements --- p.ii / Table of contents --- p.ii / Abstract --- p.xii / 撮要 --- p.xv / List of Abbreviations --- p.xvi / List of Tables --- p.xvii / List of Figures --- p.xix / TABLE OF CONTENTS / Chapter Chapter 1 --- General Introduction --- p.1 / Chapter 1.1. --- Overview of Chitinases --- p.3 / Chapter 1.1.1. --- Classification of Chitinases --- p.7 / Chapter 1.1.1.1. --- Family 19 Chitinases --- p.7 / Chapter 1.1.1.1.1. --- Class I Chitinases --- p.9 / Chapter 1.1.1.1.2. --- Class II Chitinases --- p.10 / Chapter 1.1.1.1.3. --- Class IV Chitinases --- p.10 / Chapter 1.1.1.1.4. --- Class V Chitinases --- p.11 / Chapter 1.1.1.1.5. --- Class VI Chitinases --- p.11 / Chapter 1.1.1.2. --- Family 18 Chitinases --- p.12 / Chapter 1.1.1.2.1. --- PR-8/Class III Chitinases --- p.12 / Chapter 1.1.1.2.2. --- PR-11 Chitinases --- p.15 / Chapter 1.1.1.3. --- The PR-4 Family --- p.16 / Chapter 1.1.2. --- Catalytic Mechanism of Chitinases --- p.19 / Chapter 1.1.2.1. --- Catalytic Mechanism of Family 18 Chitinases --- p.20 / Chapter 1.1.2.2. --- Catalytic Mechanism of Family 19 Chitinases --- p.21 / Chapter 1.1.3. --- Biological Properties of Chitinases --- p.22 / Chapter 1.1.3.1. --- Antifungal Activity of Chitinases in vitro --- p.22 / Chapter 1.1.3.2. --- Antifungal Activity of Chitinases in vivo --- p.23 / Chapter 1.1.3.3. --- Other Functions --- p.23 / Chapter 1.2. --- Overview of Ribonucleases --- p.25 / Chapter 1.2.1. --- Classification of Ribonucleases --- p.26 / Chapter 1.2.1.1. --- RNase T1 Family --- p.26 / Chapter 1.2.1.1.1. --- Action Mechanism of RNase T1 Family --- p.32 / Chapter 1.2.1.2. --- RNase T2 Family --- p.34 / Chapter 1.2.1.2.1. --- Action Mechanism of RNase T2 Family --- p.36 / Chapter 1.2.2. --- Biological Activities of Plant Ribonucleases --- p.38 / Chapter 1.2.2.1. --- Phosphate Remobilization --- p.38 / Chapter 1.2.2.2. --- Senescence --- p.39 / Chapter 1.2.2.3. --- Programmed Cell Death --- p.40 / Chapter 1.2.2.4. --- Plant Defense --- p.41 / Chapter 1.2.2.5. --- RNA Processing and Decay --- p.43 / Chapter 1.2.2.6. --- Antitumor Activities --- p.43 / Chapter 1.3. --- Overview of plant ribosome-inactivating proteins (RIPs) --- p.45 / Chapter 1.3.1. --- General properties of RIPs --- p.46 / Chapter 1.3.1.1. --- Classification of RIPs --- p.46 / Chapter 1.3.2. --- Activities of Ribosome-inactivating Proteins --- p.52 / Chapter 1.3.2.1. --- RNA N-glycosidase activity --- p.52 / Chapter 1.3.2.2. --- Protein synthesis inhibitory activity --- p.58 / Chapter 1.3.2.3. --- Abortifacient activity --- p.59 / Chapter 1.3.2.4. --- Immunosuppressive activity --- p.60 / Chapter 1.3.2.5. --- Antiviral activity --- p.61 / Chapter 1.3.3. --- Roles of RIPs in plants --- p.63 / Chapter 1.3.3.1. --- Defensive role of RIPs in plants --- p.63 / Chapter 1.3.3.2. --- Role of RIPs in stress adaptation in plants --- p.66 / Chapter 1.3.4. --- Possible application of RIPs --- p.67 / Chapter 1.3.4.1. --- Use of RIPs in therapies --- p.67 / Chapter 1.3.4.1.1. --- Antiviral agents --- p.67 / Chapter 1.3.4.1.2. --- Immunotoxins --- p.68 / Chapter 1.3.4.1.3. --- Anti-HIV drugs --- p.69 / Chapter 1.3.4.2. --- Use of RIPs in agriculture --- p.71 / Chapter 1.4. --- Overview of the PR-5 Family: Thaumatin-Like Proteins (TLPs) --- p.72 / Chapter 1.4.1. --- Occurrence of Thaumatin-Like Proteins --- p.76 / Chapter 1.4.2. --- Biological properties of TLPs --- p.77 / Chapter 1.4.2.1. --- Antifungal Activity --- p.77 / Chapter 1.4.2.2. --- TLPs as Anti-Freeze Protein --- p.78 / Chapter 1.4.3. --- Biotechnological Application ´ؤ Transgenic Plants --- p.79 / Chapter Chapter 2 --- Materials and Methods --- p.81 / Chapter 2.1. --- Materials --- p.81 / Chapter 2.2. --- Preparation of Crude Extract --- p.82 / Chapter 2.3. --- Purification --- p.83 / Chapter 2.4. --- Chromatography --- p.84 / Chapter 2.4.1. --- CM-Cellulose Chromatography --- p.84 / Chapter 2.4.2. --- Mono S® HR 5/5 and Mono Q® HR 5/5 --- p.85 / Chapter 2.4.3. --- Affi-gel Blue gel --- p.86 / Chapter 2.4.4. --- Superdex75 --- p.87 / Chapter 2.5. --- Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) --- p.88 / Chapter 2.6. --- Protein Concentration Determination --- p.89 / Chapter 2.7. --- Preparation of Rabbit Reticulocyte Lysate --- p.90 / Chapter 2.8. --- Determination of N-terminal Amino Acid Sequence --- p.91 / Chapter 2.9. --- Biological Activity Assays --- p.92 / Chapter 2.9.1. --- Assay for Antifungal Activity --- p.92 / Chapter 2.9.2. --- Assay for Cell-Free Translation Inhibitory Activity --- p.93 / Chapter 2.9.3. --- Assay of Cytotoxic Activity on Cancer Cell Lines --- p.94 / Chapter 2.9.4. --- Assay for HIV-1 Reverse Transcriptase (RT) Inhibitory Activity --- p.95 / Chapter 2.9.5. --- Assay of Mitogenic Activity --- p.97 / Chapter 2.9.6. --- Assay for N-Glycosidase Activity --- p.98 / Chapter 2.9.6.1. --- RNA Extraction --- p.98 / Chapter 2.9.6.2. --- Aniline Treatment --- p.99 / Chapter 2.9.6.3. --- Formaldehyde Gel Electrophoresis --- p.99 / Chapter 2.9.7. --- Assay of Ribonuclease Activity --- p.100 / Chapter 2.9.7.1. --- Assay for Yeast tRNA --- p.100 / Chapter 2.9.7.2. --- Activity toward Polyhomoribonucleotides --- p.100 / Chapter Chapter 3 --- Purification and Characterization of Pathogenesis-Related Proteins from their Respective Sources --- p.101 / Chapter 3.1. --- Purification and Characterization of Chitinase and Ribonuclease from the Roots of Panax notoginseng --- p.102 / Chapter 3.1.1. --- Introduction --- p.102 / Chapter 3.1.2. --- Results --- p.104 / Chapter 3.1.3. --- Purification --- p.107 / Chapter 3.1.3.1. --- Cation-Exchange Chromatography on CM-Cellulose --- p.108 / Chapter 3.1.3.2. --- Affinity Chromatography on Affi-gel Blue gel --- p.111 / Chapter 3.1.3.3. --- Cation-Exchange Chromatography on Mono S Column --- p.114 / Chapter 3.1.3.4. --- Gel Filtration on Superdex 75 Column --- p.115 / Chapter 3.1.4. --- Characterization of Chitinase --- p.117 / Chapter 3.1.4.1. --- N-terminal Amino Acid Sequence --- p.117 / Chapter 3.1.4.2. --- Assay for Antifungal Activity --- p.118 / Chapter 3.1.4.3. --- Assay for Cell-Free Translation-inhibitory Activity --- p.120 / Chapter 3.1.4.4. --- Assay for HIV-1 Reverse Transcriptase Inhibitory Activity --- p.120 / Chapter 3.1.5. --- Characterization of Ribonuclease --- p.121 / Chapter 3.1.5.1. --- N-terminal Amino Acid Sequence --- p.121 / Chapter 3.1.5.2. --- Assay for Ribonuclease Activity --- p.122 / Chapter 3.1.5.3. --- Assay for Cell-Free Translation-inhibitory Activity --- p.125 / Chapter 3.1.5.4. --- Assay for Antifungal Activity --- p.125 / Chapter 3.1.5.5. --- Assay for Antiproliferative Activity --- p.126 / Chapter 3.1.6. --- Discussion --- p.127 / Chapter 3.2. --- Purification and Characterization of Ribosome-Inactivating Protein and Antifungal Protein from the mushroom Lyophyllum shimeji --- p.131 / Chapter 3.2.1. --- Introduction --- p.131 / Chapter 3.2.2. --- Results --- p.132 / Chapter 3.2.3. --- Purification --- p.134 / Chapter 3.2.3.1. --- Cation-Exchange Chromatography on CM-Cellulose --- p.135 / Chapter 3.2.3.2. --- Affinity Chromatography on Affi-gel Blue Gel --- p.137 / Chapter 3.2.3.3. --- Cation-Exchange Chromatography on Mono S --- p.140 / Chapter 3.2.4. --- Characterization of Ribosome-Inactivating Protein and Antifungal Protein from Lyophyllum shimeji --- p.142 / Chapter 3.2.4.1. --- N-terminal Amino Acid Sequence --- p.142 / Chapter 3.2.4.2. --- Assay for Antifungal Activity --- p.144 / Chapter 3.2.4.3. --- Assay for N-glycosidase Activity --- p.147 / Chapter 3.2.4.4. --- Assay for Mitogenic Activity --- p.147 / Chapter 3.2.4.5. --- Assay for HIV-1 Reverse Transcriptase Inhibitory Activity --- p.148 / Chapter 3.2.5. --- Discussion --- p.150 / Chapter 3.3. --- Purification and Characterization of Ribosome-inactivating Protein from the Hypsizigus marmoreus --- p.153 / Chapter 3.3.1. --- Introduction --- p.153 / Chapter 3.3.2. --- Result --- p.154 / Chapter 3.3.3. --- Purification --- p.155 / Chapter 3.3.3.1. --- Cation-Exchange Chromatography on CM-Cellulose --- p.156 / Chapter 3.3.3.2. --- Affinity-Chromatography on Affi-gel Blue Gel --- p.158 / Chapter 3.3.3.3. --- Anion-Exchange Chromatography on Mono Q Column --- p.160 / Chapter 3.3.4. --- Characterization of Ribosome-inactivating Protein from Hypsizigus marmoreus --- p.162 / Chapter 3.3.4.1. --- N-terminal Amino Acid Sequence --- p.162 / Chapter 3.3.4.2. --- Assay for Cell-Free Translation-Inhibiting Activity --- p.163 / Chapter 3.3.4.3. --- Assay for Antifungal Activity --- p.164 / Chapter 3.3.4.4. --- Assay for N-glycosidase Activity --- p.166 / Chapter 3.3.4.5. --- Assay for HIV-1 Reverse Transcriptase Inhibitory Activity --- p.166 / Chapter 3.3.4.6. --- Assay for mitogenic Activity --- p.167 / Chapter 3.3.4.7. --- Assay for Antiproliferative Activity --- p.167 / Chapter 3.3.5. --- Discussion --- p.159 / Chapter Chapter 4 --- General Discussion --- p.170 / References --- p.172

植物合成多種發病機理相關蛋白以對抗病原體的侵襲。植物發病機理相關蛋白包括：核糖核酸酶；抗真菌蛋白；凝集素；胰蛋白酶抑制因子等。這些發病機理相關蛋白具有抗病毒，抗細菌，抗真菌，免疫調節及抗腫瘤等活性。從六種植物中提純了七個發病機理相關蛋白，包括三個凝集素，一個核糖核酸酶，兩個種抗真菌蛋白及一個胰蛋白酶抑制因子。 / 從西洋參須中提純了新的核糖核酸酶。核糖核酸酶分子量為26kDa，具有特异N末端氨基酸序列。此核糖核酸酶在 pH5 及 60℃ 條件下活性最高。它能抑制腫瘤細胞分裂及抑制人類後天免疫力缺乏症候群病毒逆轉錄酶活性。 / 從粉色菜豆及日本大花豆中提純了兩種凝集素。它們由兩個分子量為32kDa的亞基構成雙倍體。他們的活性穩定于0-60℃及3-12 pH。粉色菜豆凝集素的特异性糖基為木糖，日本大花豆凝集素的特异性糖基為半乳糖。從太子參中提純的凝集素分子量為33kDa，其活性穩定于0-60℃及2-5 pH。 這三種凝集素都具有抑制腫瘤細胞分裂及抑制人類後天免疫力缺乏症候群病毒逆轉錄酶活性。 / 提純的胰蛋白酶抑制因子分子量為21kDa。具有高耐熱及耐酸鹼性并表現出抑制腫瘤細胞分裂及抑制人類後天免疫力缺乏症候群病毒逆轉錄酶活性。從豇豆中提純的抗真菌肽分子量為5447Da，具有類防御素N末端氨基酸序列。 / Plants produce a diversity of proteins with antipathogenic activities. These proteins comprise among others, (i) ribonucleases, (ii) antifungal proteins, (iii) lectins and (iv) trypsin inhibitor with antiviral, antifungal and anticancer activities. The aim of this project was to isolate antipathogenic plant proteins including a ribonuclease from American ginseng branch roots, a trypsin inhibitor from rambutan seeds, defensin-like antifungal peptides from borlotti beans and king pole beans, and lectins from borlotti beans, Japanese large pinto beans and Pseudostellaria heterophylla. / The isolated 26-kDa ginseng branch root ribonuclease was monomeric with a novel N-terminal amino acid sequence. It exhibited maximal robonucleolytic activity toward yeast tRNA at pH 5 and 60℃. It inhibited proliferation of MCF7 human breast cancer cells and HepG2 human hepatoma cells. It also inhibited the activity of HIV-1 reverse transcriptase. / Both borlotti bean lectin and Japanese large pinto bean lectin were dimeric with a subunit molecular mass of 32-kDa. They were stable from 0℃ to 60℃ and from pH 3 to pH 12. Borlotti bean lectin was xylose-specific whereas Japanse large pinto bean lectin was galactose-specific. The 33-kDa Pseudostellaria heterophylla lectin could not be inhibited by the simple sugars tested. It was stable from 0℃ to 60℃ and from pH 2 to 5. All three isolated lectins suppressed proliferation of MCF7 and HepG2 cells and inhibited HIV-1 reverse transcriptase. / The isolated 21-kDa rambutan trypsin inhibitor has relatively high pH stability and thermostability, and exhibited HIV-1 reverse transcriptase inhibitory activity and antiproliferative activity toward a variety of tumor cells. The isolated 5447-Da king pole bean defensin-like peptide inhibited fungal growth. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Zhao, Yuan. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 202-222). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / 論文摘要 --- p.iv / Declaration --- p.v / Abbreviations --- p.vi / Table of Contents --- p.vii / List of Tables --- p.x / List of Figures --- p.xii / Chapter Chapter 1 --- Overview of Plant Defense-related Protein --- p.1 / Chapter 1.1 --- Overview of Lectins and hemagglutinins --- p.4 / Chapter 1.1.1 --- History and definition of lectins and hemagglutinins --- p.4 / Chapter 1.1.2 --- Occurrence and distribution of plant lectins --- p.6 / Chapter 1.1.3 --- Classification of lectins --- p.7 / Chapter 1.1.3.1 --- Classification of lectins on the basis of overall structure of lectin subunits --- p.7 / Chapter 1.1.3.2 --- Classification of lectins based on binding specificty to carbohydrates --- p.11 / Chapter 1.1.3.3 --- Classification of lectins according to families --- p.12 / Chapter 1.1.3.3.1 --- Legume lectins --- p.12 / Chapter 1.1.3.3.2 --- Monocot mannose-binding lectins --- p.13 / Chapter 1.1.3.3.3 --- Other lectins --- p.14 / Chapter 1.1.4 --- Defensive role of plant lectins --- p.15 / Chapter 1.1.5 --- Applications of plant lectins --- p.18 / Chapter 1.1.5.1 --- The antibacterial activity --- p.18 / Chapter 1.1.5.2 --- Anti-insect activity --- p.19 / Chapter 1.1.5.3 --- Antifungal activity --- p.21 / Chapter 1.1.5.4 --- The antiviral activity --- p.22 / Chapter 1.1.5.5 --- Lectin affinity chromatography --- p.23 / Chapter 1.1.5.6 --- Lectin microarray --- p.23 / Chapter 1.2 --- Overview of Ribonucleases --- p.26 / Chapter 1.2.1 --- History and definition of Ribonucleases --- p.26 / Chapter 1.2.2 --- Classification of Ribonucleases --- p.27 / Chapter 1.2.2.1 --- T1 Ribonucleases family --- p.27 / Chapter 1.2.2.2 --- RNase T2 family --- p.28 / Chapter 1.2.3 --- Biological activities of plant ribonucleases --- p.28 / Chapter 1.2.3.1 --- Phosphate remobilization --- p.28 / Chapter 1.2.3.2 --- Senescence --- p.29 / Chapter 1.2.3.3 --- Programmed cell death --- p.30 / Chapter 1.2.3.4 --- Plant defense --- p.31 / Chapter 1.2.3.5 --- RNA processing and decay --- p.32 / Chapter 1.2.3.6 --- Antitumor activities --- p.33 / Chapter 1.3 --- Other plant pathogen-related proteins --- p.34 / Chapter 1.3.1 --- Overview of chitinase --- p.34 / Chapter 1.3.1.1 --- Classification of chitinases --- p.35 / Chapter 1.3.1.2 --- Biological properties of chitinases --- p.38 / Chapter 1.3.2 --- Overview of plant ribosome-inactivating proteins (RIPs) --- p.41 / Chapter 1.3.2.1 --- Classification of RIPs --- p.42 / Chapter 1.3.2.2 --- Roles of RIPs in plants --- p.44 / Chapter 1.3.2.3 --- Possible application of RIPs --- p.46 / Chapter 1.3.3 --- Overview of thaumatin-like proteins (TLPs) --- p.50 / Chapter 1.3.3.1 --- Occurrence of TLPs --- p.51 / Chapter 1.3.3.2 --- Biological properties of TLPs --- p.52 / Chapter 1.4 --- Aim of this study --- p.54 / Chapter Chapter 2 --- Isolation of a lectin and an antifungal protein from Phaseolus vulgaris cv. Borlotti beans / Chapter 2.1 --- Introduction --- p.55 / Chapter 2.2 --- Materials and Methods --- p.55 / Chapter 2.3 --- Results --- p.64 / Chapter 2.4 --- Discussion --- p.79 / Chapter Chapter 3 --- Isolation of a lectin from Pinto beans (Phaseolus vulgaris pinto bean) / Chapter 3.1 --- Introduction --- p.82 / Chapter 3.2 --- Materials and Methods --- p.83 / Chapter 3.3 --- Results --- p.87 / Chapter 3.4 --- Discussion --- p.103 / Chapter Chapter 4 --- Isolation of a lectin from Pseudostellaria hetorophylla roots / Chapter 4.1 --- Introduction --- p.105 / Chapter 4.2 --- Materials and Methods --- p.107 / Chapter 4.3 --- Results --- p.110 / Chapter 4.4 --- Discussion --- p.122 / Chapter Chapter 5 --- Isolation of a ribonuclease from branch roots of American ginseng (Panax quinquefolium) / Chapter 5.1 --- Introduction --- p.124 / Chapter 5.2 --- Materials and Methods --- p.126 / Chapter 5.3 --- Results --- p.129 / Chapter 5.4 --- Discussion --- p.142 / Chapter Chapter 6 --- Isolation of a trypsin inhibitor in rambutan (Nephelium lappaceum L) seeds / Chapter 6.1 --- Introduction --- p.144 / Chapter 6.2 --- Materials and Methods --- p.147 / Chapter 6.3 --- Results --- p.152 / Chapter 6.4 --- Discussion --- p.163 / Chapter Chapter 7 --- Isoation of a defensin-like antifungal peptide from Phaseolus vulgaris cv. 'King Pole Bean' / Chapter 7.1 --- Introduction --- p.168 / Chapter 7.2 --- Materials and Methods --- p.170 / Chapter 7.3 --- Results --- p.173 / Chapter 7.4 --- Discussion --- p.181 / Chapter Chapter 8 --- Overall discussion --- p.183 / References --- p.186

Overexpression of the epidermal growth factor receptor (EGFR), a member of the ErbB family, and its closest homologue HER2, have been associated with aggressive tumour progression and reduced sensitivity to DNA-damaging agents. In order to block the proliferation of refractory tumors overexpressing EGFR, a novel strategy has been developed that sought to design molecules capable of not only blocking EGFR-TK, but also damaging DNA. These molecules, termed combi-molecules (CMs), have been shown to degrade under physical conditions to release another inhibitor of EGFR, and to be potent against tumor cells of various origins including breast, prostate and carcinoma of the vulva. However, despite their potency, their growth inhibitory IC50 values were still in the high micromolar range. In order to augment the potency of the CMs, here they were re-designed to contain two quinazoline moieties and a central N,N-bis(2-aminoethyl)methylamine spacer which, following degradation, could yield higher concentrations of free inhibitors and a more cytotoxic bifunctional DNA damaging species. Here, we describe the mechanism of action of the first prototype of this approach, JDE52, which we now classify as a double-arm CM, in comparison with ZRBA1, its closest single-arm counterpart. The results indicated that JDE52 was capable of inducing significant blockade of EGFR, DNA single-strand breaks and inter-strand cross-links. ZRBA1, its single-arm counterpart, was capable of only forming DNA single-strand breaks. The fluorescent property of FD105, the secondary inhibitor that both JDE52 and ZRBA1 are capable of releasing, has permitted the analysis of its levels in tumor cells by UV flowcytometry. It was found that JDE52 was indeed capable of significantly releasing higher levels of fluorescence (p<0.05) in human tumor cells, compared with levels of fluorescence released by ZRBA1. More importantly, JDE52 induced higher levels of apoptosis and cell killing than ZRBA1. Apoptosis was triggered by JDE52 at a faster rate than ZRBA1. The results in toto suggest that the superior potency of JDE52, when compared with ZRBA1, may be imputed to mechanisms associated with the generation of higher levels of FD105 intracellularly, and the induction of DNA cross-links, which are known to be more cytotoxic. These combined mechanisms (blockade of EGFR-TK and formation of cross-links) contributed to an accelerated rate of apoptosis in cells treated with JDE52. This study conclusively demonstrated that designing molecules as prodrugs of high levels of quinazoline inhibitors of EGFR and bifunctional DNA cross-linking species is a valid strategy to enhance the potency of CMs against refractory tumors.

Focal adhesion kinase (FAK), a non-receptor kinase, is a key regulator of integrin and focal adhesion signaling required for cancer cell survival, cell migration, and cell invasion. Amplification/Overexpression of FAK occurs in a wide variety of human cancers, supporting a role in carcinogenesis. Moreover, preclinical studies using cancer models where FAK is genetically inhibited indicate that this kinase is a potential therapeutic target to interfere with cancer progression. However, very little progress has been made in the identification of chemical inhibitors for potential therapeutic applications, in contrast to other kinases. Herein, I report optimization of the high-throughput in vitro Glo kinase assay for screening inhibitors of FAK kinase activity. Screening a large library of small molecule chemicals using these assays identified at least twenty FAK inhibitors, including a new FAK inhibitor developed by Pfizer and undergoing human clinical trials, and the non-specific kinase inhibitor staurosporine. Molecular studies of selective FAK inhibitors are undergoing in my host laboratory. In addition to this in vitro assay, I established similar assays to examine FAK kinase and adapter function in intact cells. The latter consists of ErbB-transformed cells deficient in FAK, and their matched cells where wild-type or kinase-dead FAK was restored. Biological characterization of these models revealed that both FAK kinase and adaptor activities cooperate for the regulation of cell migration, cell invasion, and tumor formation.

Bcr-abl expression being associated with anti-apoptotic signaling and expression of DNA repair enzymes, we surmised that single molecules capable of blocking abl tyrosine kinase (TK) function and damaging DNA should lead to compounds with potency superior to that of GleevecRTM. To this end, we designed novel agents termed "combi-molecules" programmed to not only behave as bcr-abl inhibitors on their own, but also to further degrade to another inhibitor and a DNA damaging species. The released inhibitor was designed to sustain bcr-abl inhibition following degradation of the combi-molecule and the DNA damaging species to activate pathways leading to apoptosis. To model this strategy termed "combi-targeting", we synthesized ZRCM5 (a monoalkyltriazene) that showed antiproliferative activity superior to that of the classical DNA damaging agent TemodalRTM, but not to that of Gleevec RTM. This result was imputed to the rather weak bcr-abl inhibitory activity of ZRCM5 and its strong DNA damaging property. Another prototype designed to contain an aniline mustard moiety (AK04) was a strong bcr-abl inhibitor but a poor DNA alkylating agent. Its cytotoxic activity was again stronger than that of the clinical alkylating agent chlorambucil but inferior to that of GleevecRTM. Further chemical studies directed at structural modification of the benzamide moiety led to the synthesis of ZRF1 with strong potency against bcr-abl TK and strong DNA damaging property. This novel optimized combi-molecule showed a 1.6-3-fold greater potency than GleevecRTM against bcr-abl expressing cells. Further investigation with ZRF1, showed that its cytotoxic potency was dependent on the p53 wild-type status of the cells. In cells expressing wild-type p53, p21 transactivation was associated with cell cycle arrest and that of Bax with apoptosis. In addition to, the pro-apoptotic effect of bcr-abl inhibition, these multiple mechanisms of action may synergistically enhance the cytotoxic potency of ZRF1 in p53 wild-type cells. The study conclusively demonstrated that p53 is a major determinant for the cytotoxic advantage of the novel combi-molecular approach in chronic myelogenous leukemia (CML), a disease in which 70-85% of all cases express wild-type p53.

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Chan Ho Yee. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 121-138). / Abstracts in English and Chinese. / ACKNOWLEDGEMENTS --- p.II / ABSTRACT --- p.III / 摘要 --- p.V / ABBREVIATIONS --- p.VI / "TABLE OF CONTENTS, " --- p.VII / LIST OF FIGURES AND TABLES --- p.XI / Chapter CHAPTER 1 --- GENERAL INTRODUCTION --- p.1 / Xenobiotic-metabolizing enzymes --- p.1 / Cytochrome P450 1 family --- p.4 / CYP1A1 --- p.5 / CYP1A2 --- p.5 / CYP1B1 --- p.5 / Transactivation of CYP1 enzymes by Aryl hydrocarbon receptor (AhR) --- p.8 / Implication of PAHs and CYP1 family in breast cancer --- p.10 / Potential role of phytochemicals on cancer prevention --- p.11 / Significance of this project --- p.13 / Chapter CHAPTER 2 --- MATERIALS AND METHODS --- p.14 / Chemicals --- p.14 / Maintenance of cells --- p.14 / Preparation of cell stock --- p.14 / Cell recovery from liquid nitrogen stock --- p.15 / Measurement of cell viability --- p.15 / Preparation of cell lysates (NP-40 cell lysis buffer) --- p.15 / XRE-luciferase gene reporter assay --- p.16 / Manipulation of DNA and RNA --- p.17 / Separation and purification of DNA from agarose gel --- p.17 / Separation of DNA from acrylamide gel --- p.17 / Restriction digestion --- p.18 / Ligation of DNA fragments --- p.18 / Transformation of DH5 a --- p.19 / Small scale plasmid purification from DH5a (mini prep) --- p.19 / Large scale plasmid isolation from DH5a (maxi-prep) --- p.20 / Construction of XRE activated luciferase reporter gene --- p.21 / Measurement of DMBA-DNA adduct formation --- p.21 / Semi-quantitative RT-PCR Assay --- p.22 / ENZYME ACTIVITIES --- p.23 / Isolation of microsomes --- p.23 / EROD activities in intact cells --- p.23 / EROD inhibition assay --- p.24 / Stattstical Analysis --- p.24 / Chapter CHAPTER 3 --- BAICALEIN INHIBITS DMBA-DNA ADDUCT FORMATION BY MODULATING CYP1A1 AND 1B1 ACTIVITIES --- p.26 / Introduction --- p.26 / Results --- p.28 / EROD activities in MCF-7 cells and inhibition assay --- p.28 / Baicalein suppressed DMBA-induced XRE-driven luciferase activities --- p.31 / Baicalein inhibited DMBA-induced CYP1A1 and CYP1B1 mRNA expression --- p.31 / The cytotoxic effect of DMBA was reduced by baicalein --- p.35 / Inhibition of DMBA-DNA adduct formation after baicalein treatment --- p.35 / Discussion --- p.39 / Chapter CHAPTER 4 --- INHIBITION OF DMBA-DNA ADDUCT FORMATION BY (-)-EPIGALLOCATECHIN GALLATE AND THEAFLAVINS --- p.41 / Introduction --- p.41 / Results --- p.45 / Persistence of DMBA-induced DNA adducts --- p.45 / Inhibition of theaflavins and EGCG on human recombinant CYP1A1 and CYP1B1 enzyme activities --- p.48 / EGCG suppressed DMBA-induced EROD activity while thealfavin had no significant effect on this --- p.48 / Kinetic analysis of EGCG on CYP1A1 and CYP1B1 activities --- p.53 / Modulation of DMBA-induced XRE-driven luciferase activities by theaflavins and EGCG --- p.56 / The influence of theaflavins and EGCG on CYP1A1 and CYP1B1 abundance --- p.56 / Discussion --- p.65 / Chapter CHAPTER 5 --- ISOFLAVONES PREVENT DMBA-INDUCED CARCINOGENESIS BY INHIBITING CYP1A1 AND CYP1B1 ACTIVITIES --- p.67 / Introduction --- p.67 / Results --- p.70 / Isoflavones inhibited DMBA-induced EROD activity in MCF-7 cells --- p.70 / Inhibition of MCF-7 microsomal EROD activities by isoflavones --- p.70 / Kinetic analysis of the inhibition of human recombinant CYP1 enzymes by isoflavones --- p.74 / XRE-driven Luciferase activities --- p.83 / Both biochanin A and genistein suppressed DMBA-induced CYP1 mRNA expression --- p.83 / Cytotoxicity of DMBA and isoflavones co-treatment --- p.88 / Isoflavones reduced the binding of activated DMBA to DNA --- p.89 / Discussion --- p.93 / Chapter CHAPTER 6 --- IN VITRO EFFECTS OF BAICALEIN AND THEAFLAVINS ON RAT HEPATIC P450 ACTIVITIES --- p.96 / Introduction --- p.96 / Results --- p.98 / Inhibition of EROD and MROD activities in rat liver microsomes by baicalein --- p.98 / Effects of theaflavins on EROD and MROD activities in rat liver microsomes --- p.102 / Kinetic studies for EROD and MROD activities of theaflavins --- p.104 / DISCUSSION --- p.114 / Chapter CHAPTER 7 --- CONCLUSION --- p.116 / APPENDIX 1 PRIMER LISTS --- p.118 / APPENDIX 2 REAGENTS --- p.119 / BIBLIOGRAPHY --- p.121

The central role of Src in the development of several malignancies including breast cancer and the accumulating evidence of its interaction with receptor tyrosine kinases (RTK), integrins and steroid receptors have identified it as an attractive therapeutic target. In the current study we have evaluated the effect of a Src/Abl kinase inhibitor SKI-606, on breast cancer growth, migration, invasion and metastasis. Treatment of human breast cancer cells MDA-MB-231 with SKI-606 caused a marked inhibition of cell proliferation, invasion and migration by inhibiting MAPK and Akt phosphorylation. For in vivo studies MDA-MB-231 cells transfected with the plasmid encoding green fluorescent protein (GFP) [MDA-MB-231-GFP] were inoculated into mammary fat pad of female BALB/c nu/nu mice. Once tumor volume reached 30-50 mm3, animals were randomized and treated with vehicle alone or 150 mg/kg of SKI-606 by daily oral gavage. Experimental animals receiving SKI-606 developed tumors of significantly smaller volume (45-54%) as compared to control animals receiving vehicle alone. Analysis of lungs, liver and spleen of these animals showed a significant decrease in GFP positive tumor metastasis in animals receiving SKI-606 at a dose that was well tolerated. Western blot analysis and immunohistochemical analysis of primary tumors showed that these effects were due to the ability of SKI-606 to block tumor cell proliferation, angiogenesis, growth factors expression and inhibition of Src mediated signalling pathways in vivo. Together the results from these studies provide compelling evidence for the use of Src inhibitors as therapeutic agents for blocking breast cancer growth and metastasis.