Urinary plasminogen activator (uPA), a member of the serine protease family, is implicated in the progression of various cancers including breast cancer due to its ability to provoke malignant cell invasion. uPA production is reported to be much higher in late stage, estrogen receptor (ER) negative breast cancer patients than those with benign hyperplasia. Since all existing evidence points to a role for uPA in breast cancer progression, exploring the mechanisms regulating its gene expression will be of immense value. Two human breast cancer cell lines were selected for this study. MDA-MB-231 represents late stage breast cancer. This cell line has high uPA expression and is highly invasive. In contrast, the MCF-7 cell line represents early stage breast cancer and fails to express detectable levels of uPA mRNA. I have demonstrated by methylation specific PCR (MSP) that the differential expression of the uPA gene in MDA MB-231 and MCF-7 cells closely correlates with the amount of methylated cytosines present within the uPA promoter in these cells. The observation that the DNA methylation status of the uPA promoter directly affects the expression of the uPA gene was then confirmed using an in vitro luciferase reporter assay. Results suggest that the accessibility of the transcription factor Ets-1 is limited by DNA methylation. I further reported increased demethylase (DMase) activity with decreased maintenance activity of methyltransferases (DNMTs), which together favor the generation of a hypomethylated uPA promoter in these highly invasive MDA-MB-231 breast cancer cells. Given the pivotal role of uPA in breast cancer progression, I then disrupted the function of uPA and studied its effects on cancer progression. The effects of an 8-mer synthetic peptide (A6) derived from the non-receptor-binding region of uPA were investigated. This peptide inhibits cancer cell invasion of both human (MDA-MB-231) and rat breast cancer cells (Mat B-III) using an in vitro cell invas
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.38200 |
| Date | January 2002 |
| Creators | Guo, Yongjing, 1972- |
| Contributors | Rabbani, Shafaat A. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Division of Experimental Medicine.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001864149, proquestno: NQ78696, Theses scanned by UMI/ProQuest. |
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