Cheung, Ka Yan. / "Aug 2010." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 157-167). / Abstracts in English and Chinese. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgments --- p.v / Table of Contents --- p.vi / List of Figures --- p.x / List of Tables --- p.xi / Abbreviations --- p.xii / Chapter Chapter1 --- General Introduction --- p.1 / Chapter 1.1 --- Cancer epidemiology and managements --- p.2 / Chapter 1.2 --- Photodynamic therapy (PDT) as cancer treatment --- p.7 / Chapter 1.3 --- Pheophorbide a (Pa) as a photosensitizer for PDT --- p.13 / Chapter 1.4 --- Aim of study --- p.15 / Chapter Chapter2 --- The anti-proliferative effect of pheophorbide a- mediated photodynamic therapy on human breast adenocarcinoma cell line MCF-7 --- p.17 / Chapter 2.1 --- Introduction / Chapter 2.1.1 --- Cell cycle regulation --- p.18 / Chapter 2.1.2 --- Growth arrest and DNA damage inducible (GADD) genes as cell cycle regulators --- p.22 / Chapter 2.2 --- Materials and Methods / Chapter 2.2.1 --- Materials / Chapter 2.2.1.1 --- Cell line --- p.29 / Chapter 2.2.1.2 --- "Cell culture medium, supplements and other reagents" --- p.29 / Chapter 2.2.1.3 --- Gene expression assay reagents --- p.30 / Chapter 2.2.1.4 --- Reagents and buffers for Western blotting --- p.32 / Chapter 2.2.1.5 --- Cell cycle analysis reagents --- p.35 / Chapter 2.2.2 --- Methods / Chapter 2.2.2.1 --- Cell line propagation and subculture --- p.36 / Chapter 2.2.2.2 --- Whole-transcript expression micro array analysis --- p.37 / Chapter 2.2.2.3 --- GADD genes expression assay- RT-PCR --- p.37 / Chapter 2.2.2.4 --- Cell cycle analysis --- p.40 / Chapter 2.2.2.5 --- Western Blotting --- p.41 / Chapter 2.2.2.6 --- Statistical analysis --- p.43 / Chapter 2.3 --- Results / Chapter 2.3.1 --- Effect of Pa-PDT on GADD genes expression by whole-transcript expression microarray analysis --- p.44 / Chapter 2.3.2 --- Effect of Pa-PDT on GADD genes expression by RT-PCR --- p.46 / Chapter 2.3.3 --- Temporal change in the cell cycle profile after Pa-PDT --- p.48 / Chapter 2.3.4 --- Effect of Pa-PDT on cell cycle associated proteins --- p.65 / Chapter 2.4 --- Discussion --- p.67 / Chapter Chapter3 --- Development of drug resistance in human breast adenocarcinoma cell line MDA and the circumvention by pheophorbide a-mediated photodynamic therapy --- p.77 / Chapter 3.1 --- Introduction / Chapter 3.1.1 --- Clinical Importance of multidrug resistance (MDR) --- p.78 / Chapter 3.1.2 --- Mechanisms of MDR --- p.78 / Chapter 3.1.3 --- Development of MDR cell lines --- p.82 / Chapter 3.1.4 --- Reversal of MDR by P-glycoprotein modulators --- p.83 / Chapter 3.1.5 --- Therapeutic potential of Pa-PDT in treating MDR cancers --- p.83 / Chapter 3.2 --- Materials and Methods / Chapter 3.2.1 --- Materials / Chapter 3.2.1.1 --- Cell line --- p.85 / Chapter 3.2.1.2 --- "Cell culture medium, supplements and other reagents" --- p.85 / Chapter 3.2.1.3 --- Cell viability assay reagents --- p.85 / Chapter 3.2.1.4 --- Gene expression assay reagents --- p.86 / Chapter 3.2.2 --- Methods / Chapter 3.2.2.1 --- Cell line propagation and subculture --- p.87 / Chapter 3.2.2.2 --- Drug-resistance development --- p.88 / Chapter 3.2.2.3 --- Measurement of cell viability - MTT reduction assay --- p.88 / Chapter 3.2.2.4 --- ABCB1 expression assay- RT-PCR --- p.89 / Chapter 3.2.2.5 --- Doxorubicin uptake assay --- p.91 / Chapter 3.2.2.6 --- Pheophorbide a uptake assay --- p.91 / Chapter 3.2.2.7 --- Statistical analysis --- p.92 / Chapter 3.3 --- Results / Chapter 3.3.1 --- Cytotoxicity of doxorubicin on MDA and MDA-R cells --- p.93 / Chapter 3.3.2 --- mRNA expression of ABCB1 (P-glycoprotein) in MDA and MDA-R cells --- p.96 / Chapter 3.3.3 --- Doxorubicin uptake by MDA and MDA-R cells --- p.98 / Chapter 3.3.4 --- Circumvention of drug resistance in MDA-R cells by Pa-PDT --- p.102 / Chapter 3.3.5 --- Pheophorbide a uptake by MDA and MDA-R cells --- p.104 / Chapter 3.4 --- Discussion --- p.106 / Chapter Chapter4 --- Synergistic anti-proliferation of pheophorbide a-mediated photodynamic therapy and doxorubicin on multidrug resistant uterine sarcoma cell line Dx5 --- p.113 / Chapter 4.1 --- Introduction / Chapter 4.1.1 --- Clinical limitations of doxorubicin as chemotherapeutic drug --- p.114 / Chapter 4.1.2 --- Clinical limitations of photodynamic therapy --- p.115 / Chapter 4.1.3 --- Combination therapy with Dox and Pa-PDT --- p.117 / Chapter 4.1.4 --- Uterine sarcoma cell line Dx5 as in vitro model for combination therapy --- p.118 / Chapter 4.2 --- Materials and Methods / Chapter 4.2.1 --- Materials / Chapter 4.2.1.1 --- Cell line --- p.120 / Chapter 4.2.1.2 --- "Cell culture medium, supplements and other reagents" --- p.120 / Chapter 4.2.1.3 --- Anti-cancer drugs --- p.121 / Chapter 4.2.1.4 --- "ROS inhibitor, α-tocopherol" --- p.121 / Chapter 4.2.1.5 --- Cell viability assay reagents --- p.122 / Chapter 4.2.1.6 --- P-glycoprotein activity assay reagents --- p.122 / Chapter 4.2.2 --- Methods - / Chapter 4.2.2.1 --- Cell line propagation and subculture --- p.123 / Chapter 4.2.2.2 --- Cell viability assay --- p.123 / Chapter 4.2.2.3 --- P-glycoprotein activity assay --- p.124 / Chapter 4.2.2.4 --- Statistical analysis --- p.125 / Chapter 4.3 --- Results / Chapter 4.3.1 --- Combination therapy of Pa-PDT and doxorubicin in Dx5 cells --- p.126 / Chapter 4.3.2 --- Effect of α-tocopherol on the synergism between Pa-PDT and doxorubicin in Dx5 cells --- p.129 / Chapter 4.3.3 --- Effect of Pa-PDT on P-glycoprotein activity in Dx5 cells --- p.132 / Chapter 4.3.4 --- Combination therapy of Pa-PDT and doxorubicin in SA cells --- p.138 / Chapter 4.4 --- Discussion --- p.141 / Chapter Chapter5 --- General Discussion --- p.148 / Chapter 5.1 --- Pa-PDT induced growth arrest and DNA fragmentation in breast cancer MCF-7 cells --- p.149 / Chapter 5.2 --- Circumvention of doxorubicin resistance by Pa-PDT in breast cancer MDA cells --- p.151 / Chapter 5.3 --- Synergistic anti-proliferation of Pa-PDT and doxorubicin on uterine sarcoma cell line Dx5 --- p.151 / Chapter 5.4 --- Clinical implication --- p.153 / Chapter 5.5 --- Conclusions and future perspectives --- p.153 / References --- p.157

Amplification of the receptor tyrosine kinase ErbB-2 has been linked to the proliferation of breast cancer cells.1,2 Trastuzumab targets the extracellular domain of ErbB-2, leading to growth inhibition of approximately 15% of the breast cancers with genomic amplification of the ERBB2 gene.3 Clinical studies have demonstrated its efficacy in both early4 and metastatic breast cancers. 5,6 However, many tumors with ERBB2 amplification are not responsive to treatment.7 Moreover, the ones that initially respond, eventually progress and acquire drug resistance.8 An in vitro model for this acquired resistance was established by Chan & al.9 The breast cancer cell line, BT474, containing amplified ERBB2, was grown in the presence of trastuzumab for several months until subclones outgrew. Gene expression profiling was performed on these clones to determine differentially expressed genes between the parental and resistant cells. DARPP-32 (Dopamine and cAMP regulated phosphoprotein of 32kDa) was, by far, the most overexpressed transcript. DARPP-32 is coamplified with ERBB2 on the same amplicon of chromosome 17.10 This protein has been mostly described in neurobiology, but DARPP-32 overexpression was recently reported in gastrointestinal, esophageal, prostate and breast cancer.11 Therefore, we suggest that overexpression of DARPP-32 can cause acquired resistance of breast cancer cells to trastuzumab. The in vitro knockout of DARPP-32, using stable shRNA transfection, abolishes the resistance to trastuzumab in the clones, while overexpression of DARPP-32 in the parental cells results in de novo resistance. Overall, our results suggest that DARPP-32 may be a potential therapeutic target in breast cancer patients who develop acquired trastuzumab resistance.

No description available.

Background. Both basal-like subtype and BRCA1-related breast cancers tend to have a poor overall prognosis and lack of effective treatments. Given that the lung cancer drug gefitinib and the leukemia drug dasatinib inhibit proteins also belonging to the molecular signature of this subtype, we and others hypothesized that they might be useful therapies for those two breast cancer subgroups. / Methods. Eight breast cancer cell lines were characterized by immunohistochemistry and western blotting and were treated with both drugs. Response was measured by using the sulphorhodamine B (SRB) assay. / Results. Two out of six basal-like cell lines were sensitive to gefitinib and five of six to dasatinib. BRCA1-related breast cancers were also responsive to dasatinib (three out of four). Moreover, EGFR and caveolin-1 act as markers for dasatinib sensitivity, but do not appear to be the primary targets of this drug. The presence of SRC but not ABL is necessary to achieve a response to dasatinib. / Conclusion. Dasatinib is more effective in the treatment of basal-like breast cancers than gefitinib and acts by inhibiting SRC and other molecules that are yet to be determined.

Qin, Jing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 162-218). / Abstract also in Chinese. / Acknowledgment --- p.i / Abstract --- p.ii / 摘要 --- p.iv / Table of Content --- p.vi / List of Figures --- p.x / List of Tables --- p.xv / Abbreviations --- p.xvii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Ganoderma spp --- p.1 / Chapter 1.1.1 --- Introduction of Ganoderma spp --- p.1 / Chapter 1.1.2 --- Bioactivities of Ganoderma spp --- p.3 / Chapter 1.1.3 --- Endocrine system and breast cancer --- p.11 / Chapter 1.1.3.1 --- Estrogen --- p.11 / Chapter 1.1.3.2 --- Estrogen receptors --- p.12 / Chapter 1.1.3.3 --- Estrogen responsive genes --- p.15 / Chapter 1.1.3.3.1 --- pS2 --- p.15 / Chapter 1.1.3.3.2 --- Progesterone receptor --- p.18 / Chapter 1.1.3.4 --- Androgen --- p.21 / Chapter 1.1.3.5 --- Androgen receptor --- p.23 / Chapter 1.1.3.6 --- Androgen responsive gene --- p.24 / Chapter 1.1.3.6.1 --- Transmembrane prostate androgen-induced RNA --- p.24 / Chapter 1.1.3.6.2 --- Uridine diphosphate glucose dehydrogenase --- p.26 / Chapter 1.1.3.7 --- Breast cancer --- p.26 / Chapter 1.2 --- "Endocrine Disruption of p,p '-DDE" --- p.28 / Chapter 1.2.1 --- Introduction of p´ةp '-DDE --- p.28 / Chapter 1.2.2 --- "p,p '-DDE in environments" --- p.29 / Chapter 1.2.3 --- "p,p '-DDE in human body" --- p.32 / Chapter 1.2.4 --- "p,p '-DDE and reproductive system" --- p.33 / Chapter 1.2.5 --- Endocrine disruptor --- p.35 / Chapter 1.2.6 --- "Action mechanism of p,p '-DDE on endocrine system" --- p.37 / Chapter 1.2.7 --- Apoptosis --- p.39 / Chapter 1.3 --- Food therapy against endocrine disruption --- p.41 / Chapter 1.3.1 --- Food therapy and functional food --- p.41 / Chapter 1.3.2 --- Ganoderma as a Functional food --- p.47 / Chapter 1.3.3 --- Cancer prevention by dietary agents --- p.47 / Chapter 1.3.4 --- Hormone therapy --- p.48 / Chapter 1.3.5 --- Hormone-related properties of Ganoderma spp --- p.50 / Chapter 1.4 --- The aim of the study --- p.51 / Chapter Chapter 2 --- Materials and Methods --- p.52 / Chapter 2.1 --- Ganoderma samples --- p.52 / Chapter 2.2 --- Artificial cultivation of Ganoderma spp --- p.54 / Chapter 2.3 --- Molecular identification of Ganoderma spp --- p.55 / Chapter 2.3.1 --- Extraction of genomic DNA --- p.55 / Chapter 2.3.2 --- Gene-specific polymerase chain reaction (PCR) --- p.56 / Chapter 2.3.3 --- Gel electrophoresis --- p.56 / Chapter 2.3.4 --- Purification of PCR amplified product for sequencing --- p.57 / Chapter 2.3.5 --- Cycle-sequencing --- p.57 / Chapter 2.3.6 --- Sequencing --- p.58 / Chapter 2.3.7 --- Sequence analysis --- p.58 / Chapter 2.4 --- Chemical analyses of Ganoderma spp --- p.59 / Chapter 2.4.1 --- Polysaccharide preparations --- p.59 / Chapter 2.4.2 --- Terpene profile --- p.60 / Chapter 2.4.3 --- Fatty acid profile --- p.60 / Chapter 2.5 --- Anti-oxidation activities --- p.61 / Chapter 2.5.1 --- Superoxide radical scavenging assay --- p.61 / Chapter 2.5.2 --- DPPH radical scavenging assay --- p.62 / Chapter 2.6 --- Anti-proliferation effect on human breast cancer cells --- p.62 / Chapter 2.7 --- Hormone-like effects --- p.63 / Chapter 2.7.1 --- E-screen test --- p.63 / Chapter 2.7.2 --- In vitro estrogen receptors (ERs) competitor binding assays --- p.64 / Chapter 2.7.3 --- "Recombinant yeast cell based ER-, AR- and PGR-responsible promoter assays" --- p.65 / Chapter 2.7.3.1 --- Recombinant yeasts --- p.65 / Chapter 2.7.3.2 --- Growth medium for recombinant yeasts --- p.66 / Chapter 2.7.3.3 --- "ER, AR and PGR assays" --- p.67 / Chapter 2.7.3.4 --- β-Galactosidase assay --- p.67 / Chapter 2.7.4 --- Real time PCR --- p.68 / Chapter 2.8 --- Flow cytometry --- p.71 / Chapter 2.9 --- Comet assay --- p.71 / Chapter 2.10 --- DNA microarray --- p.73 / Chapter 2.10.1 --- Total RNA isolation --- p.73 / Chapter 2.10.2 --- cDNA synthesis --- p.73 / Chapter 2.10.3 --- Preparation of labelled cDNA --- p.74 / Chapter 2.10.4 --- cDNA purification --- p.74 / Chapter 2.10.5 --- Oligo GEArray hybridization --- p.75 / Chapter 2.10.6 --- Chemiluminescent detection --- p.76 / Chapter 2.10.7 --- Data analysis --- p.77 / Chapter Chapter 3 --- Results --- p.78 / Chapter 3.1 --- Analysis of Ganderma spp --- p.78 / Chapter 3.1.1 --- Mycelia and fruiting bodies --- p.78 / Chapter 3.1.2 --- Identification of Ganoderma spp --- p.79 / Chapter 3.1.3 --- Chemical properties of samples --- p.80 / Chapter 3.1.4 --- Anti-oxidation activities --- p.90 / Chapter 3.1.5 --- Anti-proliferation effect on human breast cancer cells --- p.90 / Chapter 3.1.6 --- Hormone-like bioactivities --- p.93 / Chapter 3.1.6.1 --- E-screen test --- p.93 / Chapter 3.1.6.2 --- In vitro estrogen receptors (ERs) competitor binding assays --- p.94 / Chapter 3.1.6.3 --- "Recombinant yeast cell-based ER-, AR- and PGR-responsible promoter assays" --- p.95 / Chapter 3.1.6.4 --- ER- and AR-pathway gene expression by real time PCR --- p.97 / Chapter 3.2 --- "Action mechanism of p,p' -DDE" --- p.99 / Chapter 3.2.1 --- E-screen --- p.99 / Chapter 3.2.2 --- In vitro estrogen receptors (ERs) competitor binding assays --- p.101 / Chapter 3.2.3 --- Recombinant yeast cell based ER- and AR-responsible promoter assays --- p.103 / Chapter 3.2.4 --- ER- and AR-pathway gene expression by real time PCR --- p.106 / Chapter 3.3 --- Ganoderma tsugae mycelia extract against p.p' -DDE --- p.109 / Chapter 3.3.1 --- E-screen test --- p.109 / Chapter 3.3.2 --- ER- and AR-pathway gene expression by real time PCR --- p.110 / Chapter 3.3.3 --- Analysis of cell cycle --- p.112 / Chapter 3.3.4 --- Analysis of DNA damage --- p.114 / Chapter 3.3.5 --- Analysis of sub-G1 peak --- p.117 / Chapter 3.3.6 --- DNA damage and apoptosis relative gene expression by real time PCR --- p.120 / Chapter 3.3.7 --- DNA microarray --- p.121 / Chapter Chapter 4 --- Discussion --- p.131 / Chapter 4.1 --- Analysis of Ganoderma spp --- p.131 / Chapter 4.2 --- Effects of p.p´ة-DDE --- p.144 / Chapter 4.3 --- Protective effects of G. tsugae against p.p' -DDE --- p.151 / Chapter 4.4 --- Further investigation --- p.159 / Chapter 4.5 --- Conclusion --- p.160 / References --- p.162

No description available.

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

Additionally, we showed that SeC induced S-phase arrest in MCF-7 cells associated with a marked decrease in the protein expression of cyclin A, D1 and D3 and cyclin-dependent kinases (CDK) 4 and 6, with concomitant induction of p21waf1/Cip1, p27Kip1 and p53. Expose of MCF-7 cells to SeC resulted in delayed onset of apoptosis as evidenced by caspase activation, PARP cleavage and DNA fragmentation. SeC treatment also triggered the activation of JNK, p38 MAPK, ERK and Akt phosphorylation. Inhibitors of ERK (U0126) or Akt (LY294002), but not JNK (SP600125) and p38 MAPK (SB203580), significantly suppressed SeC-induced S-phase arrest and apoptosis in MCF-7 cells. In conclusion, our findings establish a mechanistic link between the PI3K/Akt pathway, MAPK pathway and SeC-induced cell cycle arrest and apoptosis in human breast cancer cells. (Abstract shortened by UMI.) / The role of selenium as potential cancer chemopreventive and chemotherapeutic agents has been supported by epidemiological, preclinical and clinical studies. Although cell apoptosis has been evidenced as a critical mechanism mediating the anticancer activity of selenium, the underlying molecular mechanisms remain elusive. In the present study, selenocystine (SeC), a novel organic selenocompound, is identified as a novel antiproliferative agent with a broad spectrum of inhibition against eight human cancer cell lines with the IC50 values ranged from 3.6 to 37.0 muM. Despite this potency, SeC was relatively nontoxic toward HS68 human fibroblasts with an IC 50 value exceeded 400 muM. Further investigation on the molecular mechanisms indicated that SeC induced caspase-independent apoptosis in MCF-7 breast carcinoma cells, which was accompanied by poly(ADP-ribose) polymerase (PARP) cleavage, caspase activation, DNA fragmentation, phosphatidylserine exposure and nuclear condensation. Moreover, SeC induced the loss of mitochondrial membrane potential (DeltaPsim) by regulating the expression and phosphorylation of pro-surivival and pro-apoptotic Bcl-2 family members. Loss of DeltaPsim led to the mitochondrial release of cytochrome c and apoptosis-inducing factor (AIF) which subsequently translocated into the nucleus and induced chromatin condensation and DNA fragmentation. MCF-7 cells exposed to SeC shown increase in total p53 and phosphorylated p53 on serine residues of Ser15, Ser20, and Ser392 prior to mitochondrial dysfunction. Silencing and attenuation of p53 expression with RNA interference and pifithrin-alpha treatment respectively, partially suppressed SeC-induced cell apoptosis. Furthermore, generation of reactive oxygen species (ROS) and subsequent induction of DNA strand breaks were found to be upstream cellular events induced by SeC. The thiol-reducing antioxidants, N-acetylcysteine and glutathione, completely blocked the initiation and execution of cell apoptosis. Taken together, these results suggest that SeC, as a promising anticancer selenocompound, induces caspase-independent apoptosis in MCF-7 cells mediated by ROS generation and p53 phosphorylation through regulating the mitochondrial membrane permeability. / Chen, Tianfeng. / Adviser: Yun-Shing Wong. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3260. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 124-136). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

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.

No description available.