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dc.contributor.authorNesset, Kirsten A.
dc.contributor.otherQueen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.))en
dc.date2012-09-26 18:19:11.006en
dc.date.accessioned2012-09-26T22:54:25Z
dc.date.available2013-09-22T08:00:18Z
dc.date.issued2012-09-26
dc.identifier.urihttp://hdl.handle.net/1974/7521
dc.descriptionThesis (Master, Biochemistry) -- Queen's University, 2012-09-26 18:19:11.006en
dc.description.abstractEpidemiological studies have identified psychological stress as a significant risk factor in breast cancer. The stress response is regulated by the HPA axis in the brain and is mediated by glucocorticoid receptor (GR) signalling. It has been found that early life events can affect epigenetic programming of GR, and methylation of the GR promoter has been reported in colorectal tumourigenesis. Decreased GR expression has also been observed in breast cancer. In addition, it has been previously demonstrated that unliganded GR can serve as a direct activator of the BRCA1 promoter in mammary epithelial cells. We propose a model whereby methylation of the GR promoter in the breast significantly lowers GR expression, resulting in insufficient BRCA1 promoter activation and an increased risk of developing cancer. Antibody-based methylated DNA enrichment was followed by qPCR analysis (MeDIP-qPCR) in a novel assay developed to detect locus-specific methylation levels. It was found that 13% of primary breast tumours were hypermethylated at the GR proximal promoter whereas no methylation was detected in normal tissue. RT-PCR and 5’ RACE analysis identified exon 1B as the predominant alternative first exon in the breast. Tumours methylated near exon 1B had decreased GR expression compared to unmethylated samples, suggesting that this region is important for transcriptional regulation of GR. It was also determined that GR and BRCA1 expression was decreased in breast tumour compared to normal tissue. Furthermore, the relative expression of GR and BRCA1 measured by qRT-PCR was correlated in normal tissue but this association was not found in tumour tissue. From this, it appears that lower GR levels with associated decreased BRCA1 expression in tissues may be a predisposing factor for breast cancer. Based on these results we propose a role for GR as a potential tumour suppressor gene in the breast due to its association with BRCA1, also a tumour suppressor gene, as well as its consistently decreased expression in breast tumours and methylation of its proximal promoter in a subset of cancer patients.en_US
dc.languageenen
dc.language.isoenen_US
dc.relation.ispartofseriesCanadian thesesen
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.subjectGlucocorticoid Receptoren_US
dc.subjectEpigeneticen_US
dc.subjectBreast canceren_US
dc.subjectMethylationen_US
dc.titleCharacterization of Glucocorticoid Receptor Promoter Methylation in Breast Canceren_US
dc.typeThesisen_US
dc.description.restricted-thesisThis thesis is to be restricted as there is interest in obtaining a patent for elements of this research project in the future.en
dc.description.degreeMasteren
dc.contributor.supervisorMueller, Christopheren
dc.contributor.departmentBiochemistryen
dc.embargo.terms1825en


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