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.

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Yau Mei-sze. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 96-112). / Abstracts in English and Chinese. / Abstract / Abstract (Chinese Version) / Acknowledgements / List of Abbreviations / Table of Contents / List of Tables / List of Figures / Chapter Chapter 1 --- Introduction / Chapter Chapter 2 --- Literature Review / Chapter 2.1 --- Hepatocellular Carcinoma / Chapter 2.2 --- Epidermal Growth Factor Receptor / Chapter 2.2.1 --- Activation of Epidermal Growth Factor Receptor / Chapter 2.2.2 --- Epidermal Growth Factor Receptor Signaling Pathways / Chapter 2.2.3 --- Expression Level and Patient Survival / Chapter 2.2.4 --- Epidermal Growth Factor Receptor Activity and Tumor Cell Growth / Chapter 2.2.5 --- Epidermal Growth Factor Receptor Activity and Radiation / Chapter 2.3 --- "Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor, ZD1839" / Chapter 2.3.1 --- Tumor Cell Growth Control Activities of ZD1839 / Chapter 2.3.2 --- Factors Affecting the Tumor Cell Growth Control Activities of ZD1839 / Chapter 2.3.3 --- Radiosensitization Activities of ZD1839 / Chapter 2.3.4 --- Factors Affecting the Radiosensitization Activities of ZD1839 / Chapter 2.4 --- Study Objectives / Chapter Chapter 3 --- Materials and Methods / Chapter 3.1 --- ZD1839 / Chapter 3.2 --- Cell lines and Cell Culture / Chapter 3.3 --- Immunoblot Analysis / Chapter 3.3.1 --- Total Protein Extraction / Chapter 3.3.2 --- Protein Amount Determination / Chapter 3.3.3 --- Protein Separation / Chapter 3.3.4 --- Blotting / Chapter 3.3.5 --- Antibody Labeling / Chapter 3.3.6 --- Detection of Antibody Binding / Chapter 3.4 --- Cytotoxicity Assay / Chapter 3.5 --- Nucleotide sequence analysis / Chapter 3.5.1 --- Total RNA Extraction / Chapter 3.5.2 --- RNA Amount Determination / Chapter 3.5.3 --- Reverse Transcription - Polymerase Chain Reaction (RT-PCR) / Chapter 3.5.3.1 --- Reverse Transcription / Chapter 3.5.3.2 --- High Fidelity Polymerase Chain Reaction / Chapter 3.5.4 --- Purification of PCR Product / Chapter 3.5.5 --- Cycle Sequencing Reaction / Chapter 3.5.6 --- DNA Precipitation and Sequencing / Chapter 3.6 --- Clonogenic Assay / Chapter 3.7 --- Immunohistochemical Analysis / Chapter Chapter 4 --- Results / Chapter 4.1 --- Immunoblot Analysis / Chapter 4.2 --- Cytotoxicity Assay / Chapter 4.2.1 --- Effect of ZD 1839 on cell morphology / Chapter 4.2.2 --- Effect of ZD 1839 on cell growth / Chapter 4.3 --- Nucleotide sequence analysis / Chapter 4.3.1 --- RNA Concentration of HCC cells / Chapter 4.3.2 --- Sequencing of TK domain within EGFR / Chapter 4.3.3 --- Sequencing of TK domain within HER2 / Chapter 4.4 --- Clonogenic assay / Chapter 4.4.1 --- Effects of ZD 1839 pre-treatment on radiation response / Chapter 4.4.2 --- Effects of ZD 1839 continuous treatment on radiation response / Chapter 4.5 --- Immunohistochemical Analysis / Chapter Chapter 5 --- Discussion / Chapter 5.1 --- Important Findings / Chapter 5.2 --- EGFR Expression of HCC Cells / Chapter 5.3 --- Cytotoxicity of ZD1839 on HCC Cell Lines / Chapter 5.4 --- Factors Affecting the Cytotoxicity of ZD1839 / Chapter 5.4.1 --- Effect of EGFR Expression on ZD1839 Cytotoxicity / Chapter 5.4.2 --- Effect of EGFR Mutations on ZD 1839 Cytotoxicity / Chapter 5.4.3 --- Effect of HER2 Expression on ZD1839 Cytotoxicity / Chapter 5.4.4 --- Effect of HER2 Mutations on ZD 1839 Cytotoxicity / Chapter 5.5 --- Radiation Response ofHCC Cell Lines upon ZD1839 Treatment / Chapter 5.6 --- Factors Affecting Radiation Response of ZD1839-treated HCC Cell Lines / Chapter 5.6.1 --- Effect of Growth Arrest on Radiation Response of HCC Cell Lines / Chapter 5.6.2 --- Other Factors Affecting Radiation Response of HCC Cell Lines / Chapter Chapter 6 --- Conclusion / References