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UBC Theses and Dissertations

Marker analysis for the detection of metastatic breast cancer Hornby, Ann Elizabeth


The main objective of this thesis was to examine the possibility of transferring the current immunologic methods of detecting metastatic breast cancer to a more specific, more sensitive, and less subjective nucleic acid-based technology. The rational was two-fold: (1) early detection of metastatic disease may be useful in determining treatment protocols for breast cancer patients; and (2) the ability to detect small numbers of tumor cells in blood or bone marrow may help in monitoring the effectiveness of treatment. Chronic myelogenous leukemia (CML) was successfully used as a model system for the development of PCR for the detection of rare mRNAs expressed in blood or bone marrow. The level of sensitivity achieved was 1/10⁶ cells. Once the PCR technology was established CML bone marrow was then used to study the effect of Benzoporphyrin derivative mono acid-A (BPD-MA) on the enzymatic activity of Taq polymerase. BPD-MA is a photoactive drug being developed by Quadra Logic Technologies Ltd., with potential use as a bone marrow purging agent for patients with metastatic breast cancer undergoing autologous bone marrow transplantation. BPD-MA did not interfere with the ability of Taq polymerase to detect rare mRNA expression in bone marrow, therefore PCR technology could be used to monitor the effectiveness of treatment after bone marrow purging and autologous bone marrow transplantation. Using RNA PCR technology the expression of three genes currently used for the detection of metastatic breast cancer by immunological methods was studied. Polymorphic epithelial mucin gene expression was analyzed in breast cancer cell lines, and normal blood and bone marrow. No expression was detected in bone marrow; however, expression was detected in peripheral blood. This may account for reports of cross-reactivity of mAbs directed against epithelial mucins detected in peripheral blood. Keratin 18 and 8 expression was analyzed in a similar manner. Keratin 18 expression was detected in both blood and bone marrow, whereas, keratin 8 expression was detected in blood only. The expression of both keratins appeared to be the result of transcriptionally active processed pseudogenes. Keratin 8 pseudogene expression also appeared to be differentially regulated in breast versus peripheral blood cells.

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