Retinoids are derivatives of vitamin A with demonstrated therapeutic potential for the treatment of breast cancer. The efficacy of retinoids in vitro and in vivo correlates with the expression of the estrogen receptor alpha (ERalpha). The role of ERalpha in mediating RA-induced sensitivity is not understood and is further complicated by the recent discovery of ERalpha. This dissertation explores the transcriptional, as well as proliferative, response to RA in human breast cancer cells expressing ERbeta or ERbeta. First, ER-negative breast cancer cells were stably transduced with ERalpha-deletion mutants using retroviral technology. We compared the effect of the ERalpha wild-type, ERalpha-deletion mutants or the parental ER-negative cells on transcriptional activity from the RARbeta2 promoter, a gene regulated by retinoids and potentially involved in retinoid-mediated growth inhibition. We observed that expression of ERalpha suppressed basal expression of the RA-responsive gene RARbeta2, while allowing it to be strongly induced by RA. Repression of basal RARbeta2 transcription was confirmed by transient expression of a reporter plasmid containing the RARbeta2 minimal promoter. We further determined that RARbeta2 induction required the N-terminal AF-1 containing region of ERalpha, including the DNA-binding domain, but was independent of the C-terminal ligand-binding domain. The effect of ERalpha was specific for RAR-mediated transcription and did not alter transcription from vitamin D or thyroid hormone response elements. Moreover, the cross-talk between ERalpha and RAR was not mediated by sequestration of a number of common co-regulators. To characterize the growth and transcription effect of ERbeta on retinoid-mediated pathways, we generated stable transfectants using this isoform. Significant RA-mediated growth inhibition was observed in the ERbeta-positive cells and not in the parental ER-negative cells. Furthermore, RA altered ERbeta-me
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.84316 |
| Date | January 2004 |
| Creators | Rousseau, Caroline |
| Contributors | Miller, Wilson H., Jr. (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: 002141459, proquestno: AAINQ98361, Theses scanned by UMI/ProQuest. |
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