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