Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Proteolytic mechanisms involved in the metastasis of human melanoma cells
The metastatic process requires that tumour cells are capable of traversing various micro-environmental barriers, such as the basement membrane. There are various proteolytic mechanisms which could contribute to the process, plasminogen activation by tissue plasminogen activator (tPA) and urokinase...
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
Division of Chemical Pathology
2018
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613234015502336 |
|---|---|
| access_status_str | Open Access |
| author | Fletcher, Jean Margaret |
| author2 | Dowdle, Eugene B |
| author_browse | Dowdle, Eugene B Fletcher, Jean Margaret |
| author_facet | Dowdle, Eugene B Fletcher, Jean Margaret |
| author_sort | Fletcher, Jean Margaret |
| collection | Thesis |
| description | The metastatic process requires that tumour cells are capable of traversing various micro-environmental barriers, such as the basement membrane. There are various proteolytic mechanisms which could contribute to the process, plasminogen activation by tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA) is one such mechanism. Extensive reports in the literature (reviewed in the introduction) indicate that most tumour cells synthesize uPA and that it is this enzyme, particularly when receptor-bound, which plays a role in invasion. UCT-Mel 3 is a human malignant melanoma cell line which was established in our laboratory, and has been shown to be highly metastatic in the nude mouse. This cell line is typical of many melanomas in that it synthesizes only tPA and not uPA. In part 1 of this thesis I further investigated the plasminogen activator production by these cells (at the level of mRNA as well as activity) as well as expression of plasminogen activator inhibitor PAl-1 and receptors for tPA and uPA (uPAR). UCT-Mel 3 cells expressed uPAR although uPA was not detected. I also examined cells cultured from two metastatic deposits. Interestingly, the metastatic cells produced PAl-1 which was undetected in the parent cells. After confirming that UCT-Mel 3 do not express detectable levels of uPA, I attempted (in part 2) to determine whether tPA could play a comparable role to that of uPA in the invasive process. My strategy was to inhibit the expression of tPA via two different methods, namely the use of antisense RNA and ribozyme. I then hoped to isolate clones producing no tPA, which would have been injected into nude mice in order to assay for metastasis. Unfortunately, neither of these methods proved to be successful in abrogating tPA expression. I was thus unable to achieve the ultimate aim of the project. However, during the course of the study a number of unforeseen problems arose. Firstly, the clonal variation within the cell population, and secondly, my inability to obtain antisense transfectants. I have speculated that a possible reason for the latter may be that the cells are in fact unable to grow in the absence of tPA. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/27116 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:32:52.713Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2018 |
| publishDateRange | 2018 |
| publishDateSort | 2018 |
| publisher | Division of Chemical Pathology |
| publisherStr | Division of Chemical Pathology |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/27116 Proteolytic mechanisms involved in the metastasis of human melanoma cells Fletcher, Jean Margaret Dowdle, Eugene B Melanoma Neoplasm metastasis Protease inhibitors The metastatic process requires that tumour cells are capable of traversing various micro-environmental barriers, such as the basement membrane. There are various proteolytic mechanisms which could contribute to the process, plasminogen activation by tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA) is one such mechanism. Extensive reports in the literature (reviewed in the introduction) indicate that most tumour cells synthesize uPA and that it is this enzyme, particularly when receptor-bound, which plays a role in invasion. UCT-Mel 3 is a human malignant melanoma cell line which was established in our laboratory, and has been shown to be highly metastatic in the nude mouse. This cell line is typical of many melanomas in that it synthesizes only tPA and not uPA. In part 1 of this thesis I further investigated the plasminogen activator production by these cells (at the level of mRNA as well as activity) as well as expression of plasminogen activator inhibitor PAl-1 and receptors for tPA and uPA (uPAR). UCT-Mel 3 cells expressed uPAR although uPA was not detected. I also examined cells cultured from two metastatic deposits. Interestingly, the metastatic cells produced PAl-1 which was undetected in the parent cells. After confirming that UCT-Mel 3 do not express detectable levels of uPA, I attempted (in part 2) to determine whether tPA could play a comparable role to that of uPA in the invasive process. My strategy was to inhibit the expression of tPA via two different methods, namely the use of antisense RNA and ribozyme. I then hoped to isolate clones producing no tPA, which would have been injected into nude mice in order to assay for metastasis. Unfortunately, neither of these methods proved to be successful in abrogating tPA expression. I was thus unable to achieve the ultimate aim of the project. However, during the course of the study a number of unforeseen problems arose. Firstly, the clonal variation within the cell population, and secondly, my inability to obtain antisense transfectants. I have speculated that a possible reason for the latter may be that the cells are in fact unable to grow in the absence of tPA. 2018-01-30T13:37:18Z 2018-01-30T13:37:18Z 1994 Master Thesis Masters MSc (Med) http://hdl.handle.net/11427/27116 eng application/pdf Division of Chemical Pathology Faculty of Health Sciences University of Cape Town |
| spellingShingle | Melanoma Neoplasm metastasis Protease inhibitors Fletcher, Jean Margaret Proteolytic mechanisms involved in the metastasis of human melanoma cells |
| thesis_degree_str | Master's |
| title | Proteolytic mechanisms involved in the metastasis of human melanoma cells |
| title_full | Proteolytic mechanisms involved in the metastasis of human melanoma cells |
| title_fullStr | Proteolytic mechanisms involved in the metastasis of human melanoma cells |
| title_full_unstemmed | Proteolytic mechanisms involved in the metastasis of human melanoma cells |
| title_short | Proteolytic mechanisms involved in the metastasis of human melanoma cells |
| title_sort | proteolytic mechanisms involved in the metastasis of human melanoma cells |
| topic | Melanoma Neoplasm metastasis Protease inhibitors |
| url | http://hdl.handle.net/11427/27116 |
| work_keys_str_mv | AT fletcherjeanmargaret proteolyticmechanismsinvolvedinthemetastasisofhumanmelanomacells |