Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 89-99). Also available on the World Wide Web.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Chronic Myeloid Leukaemia (CML) is a clonal haemopoietic stem cell (HSC) disorder characterised by the presence of a disease-specific gene, BCR-ABL, which leads to the production of a bcr-abl mRNA transcript. CML is an ideal candidate for gene therapy using ribozymes (Rz), catalytic RNA molecules that cleave and inactivate target RNA in a sequence specific manner. Limited data is available on the activity of ribozymes in human CML cells. In this study, hammerhead ribozyme sequences directed against the b3a2 bcr-abl mRNA sequence (Rz6-Rz10) were cloned into several retroviral vectors. Initial experiments using MSCVHSA based retroviral constructs failed to express the sequences in cell lines. Rz cDNA fragments were then cloned into an LNL6 based retroviral vector (LGL1) encoding a GFP reporter gene and stable LGLRz constructs produced. Using cell sorting, high-titre PA317 producer cell line clones were isolated. Transcriptional silencing of the LGLRz6 producer cell line occurred with prolonged culture, with partial reversal on treatment with the demethylating agent 5' azacytidine. To assess the activity of these constructs in human cells, CD34+ HSC were isolated from newly diagnosed b3a2 Ph+ CML patients. Cells were transduced with either control LGL vector or the LGLRz6 construct. Transduced human cells were sorted based on GFP expression and placed into long-term HSC culture (LTC-IC assays). Using a common cDNA, RT-PCR was performed to detect the expression of both the transgene and bcr-abl in individual colonies derived from the LTCIC assay at various time points, allowing assessment of the effect of transgene expression on bcr-abl expression. LGLRz transgene expression was detectable for up to 6 weeks in culture. Colony RT-PCR results from 3 patients showed that expression of the LGLRz6 construct was associated with decreased bcr-abl expression. It also appeared that the reduced bcr-abl expression decreased the proliferation of Ph+ cells leading to their loss from culture. In summary, these results appear to show an effect of a retroviral vector containing a bcr-abl Rz sequence on human CML HSC. Targeting of bcr-abl remains a valid therapeutic goal in the Imatinib era, particularly if problems related to effective ribozyme delivery and targeting can be overcome.

"October 2002" Bibliography: leaves 159-198. This thesis describes the mapping of the breakpoints of three different chromosome rearrangements, all involving 1p36, in acute myeloid leukaemia (AML) patients, and an investigation into the molecular outcomes of these rearrangements.

Acute Myeloid Leukaemia (AML) is a disease normally found in elderly patients, with the median age of presentation at about 68 years. At this age, many of the patients are frail and unlikely to respond well to intensive chemotherapy treatments. Conventional chemotherapy eradicates the proliferating leukaemic progenitors while leaving the quiescent leukaemic stem cells undisturbed. These quiescent LSCs are able to then bring about leukaemic relapse. Fumagillin is a natural metabolite from Asperigillus fumigatus that is generally used as an anti-microbial agent but it is also known to bind to intracellular MetAP-II and inhibit endothelial cell growth. Many cancers are found to have an over expression of MetAP-II. In the past, MetAP-II inhibitors have been tested and shown success in angiogenesis inhibition and tumor reduction. The aim of this study is to observe whether methionine aminopeptidase-2 inhibitors can be used in the treatment of acute myeloid leukemia. The investigation included a dose response comparison of various AML cell lines to fumagillin treatment, cell proliferation assay, a colony forming unit assay, and cell cycle analysis of KG-1 cells following three days of fumagillin treatment. I have determined that fumagillin does indeed decrease the cellular proliferation of KG-1 in vivo and at 10μM, prevents colony formation in methylcellulose plating. There is an increase in cells found in the sub-G1 phase with fumagillin treatment, as analyzed by flow cytometry. It is interpolated that fumagillin treatment increases AML cell apoptosis, in addition to hindering its ability to grow in culture. / published_or_final_version / Medicine / Master / Master of Medical Sciences

No description available.

This thesis is submitted as a PhD by Portfolio of Publications. It represents an integrated examination of the BCR-ABL oncogene as a precise indicator of treatment response, drug resistance and relapse in patients with chronic myeloid leukaemia (CML). / Thesis (PhDBiomedicalScience)--University of South Australia, 2005.

Chronic Myeloid Leukaemia (CML) is a clonal haemopoietic stem cell (HSC) disorder characterised by the presence of a disease-specific gene, BCR-ABL, which leads to the production of a bcr-abl mRNA transcript. CML is an ideal candidate for gene therapy using ribozymes (Rz), catalytic RNA molecules that cleave and inactivate target RNA in a sequence specific manner. Limited data is available on the activity of ribozymes in human CML cells. In this study, hammerhead ribozyme sequences directed against the b3a2 bcr-abl mRNA sequence (Rz6-Rz10) were cloned into several retroviral vectors. Initial experiments using MSCVHSA based retroviral constructs failed to express the sequences in cell lines. Rz cDNA fragments were then cloned into an LNL6 based retroviral vector (LGL1) encoding a GFP reporter gene and stable LGLRz constructs produced. Using cell sorting, high-titre PA317 producer cell line clones were isolated. Transcriptional silencing of the LGLRz6 producer cell line occurred with prolonged culture, with partial reversal on treatment with the demethylating agent 5' azacytidine. To assess the activity of these constructs in human cells, CD34+ HSC were isolated from newly diagnosed b3a2 Ph+ CML patients. Cells were transduced with either control LGL vector or the LGLRz6 construct. Transduced human cells were sorted based on GFP expression and placed into long-term HSC culture (LTC-IC assays). Using a common cDNA, RT-PCR was performed to detect the expression of both the transgene and bcr-abl in individual colonies derived from the LTCIC assay at various time points, allowing assessment of the effect of transgene expression on bcr-abl expression. LGLRz transgene expression was detectable for up to 6 weeks in culture. Colony RT-PCR results from 3 patients showed that expression of the LGLRz6 construct was associated with decreased bcr-abl expression. It also appeared that the reduced bcr-abl expression decreased the proliferation of Ph+ cells leading to their loss from culture. In summary, these results appear to show an effect of a retroviral vector containing a bcr-abl Rz sequence on human CML HSC. Targeting of bcr-abl remains a valid therapeutic goal in the Imatinib era, particularly if problems related to effective ribozyme delivery and targeting can be overcome.

Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 2003. / "October 2002" Bibliography: leaves 159-198.

Thesis (M. Med. Sc.)--University of Hong Kong, 2008. / Includes bibliographical references (p. 48-60)