Numerous experiments have shown that pregnancy induces a protective effect against tumor development in the mammary glands of both rodents and humans. This protective effect can be mimicked in rats by administration of estrogen and progesterone prior to chemical treatment. Several questions regarding athe hormonal induction of the protective effect on mammary tumorigenesis remain unanswered. These questions involve the dose and duration of hormones required to induce a protective state, the stability of the protective state. This project addresses three specific aims which are relevant to understanding the cellular and molecular basis of the protective effect. The model chosen to address these aims is N-methyl-N- nitrosourea (MNU) induced mammary tumorigenesis in inbred Wistar-Furth rats pretreated with estrogen and progesterone.
Specific aim 1 determines the minimum hormone doses and time required to induce a protective effect. The expression of TGFbeta II will be assessed in the resist ant and susceptible mammary gland to provide an endpoint for the resistant cell phenotype.
Specific Aim 2 examines the persistence of the resistant state fy administering MNU to rats at 28, 78 and 128 days after the end of hormone treatment.
Specific Aim 3 examines whether resistance resides within the mammary gland parenchyma or stromal compartment using the mammary fat pad transplantation system. Glands from both virgin and hormone-treated animals will be transplanted into rats and examined for their respective susceptibility to MNU.
Specific Aim 4 will establish mammary epithelial cell lines from susceptible and resistant mammary glands and from MNU-induced mammary tumors. These cell lines will be used as recipient cells for transfection experiments examining the consequences of overexpression of specific genes isolated in other projects. The results of these experiments will establish a minimal hormonal regiment for prevention of experimental breast cancer and a firm rationale for developing hormonal intervention as a feasible approach for human cancer prevention.
| Medina, Daniel; Kittrell, Frances; Hill, Jamal et al. (2009) Prevention of tumorigenesis in p53-null mammary epithelium by rexinoid bexarotene, tyrosine kinase inhibitor gefitinib, and celecoxib. Cancer Prev Res (Phila) 2:168-74 |
| Rajkumar, Lakshmanaswamy; Kittrell, Frances S; Guzman, Raphael C et al. (2007) Hormone-induced protection of mammary tumorigenesis in genetically engineered mouse models. Breast Cancer Res 9:R12 |
| Medina, D; Kittrell, F S; Tsimelzon, A et al. (2007) Inhibition of mammary tumorigenesis by estrogen and progesterone in genetically engineered mice. Ernst Schering Found Symp Proc :109-26 |
| Caulin, Carlos; Nguyen, Thao; Lang, Gene A et al. (2007) An inducible mouse model for skin cancer reveals distinct roles for gain- and loss-of-function p53 mutations. J Clin Invest 117:1893-901 |
| Goepfert, Thea M; Moreno-Smith, Myrthala; Edwards, David G et al. (2007) Loss of chromosomal integrity drives rat mammary tumorigenesis. Int J Cancer 120:985-94 |
| Ginger, Melanie R; Shore, Amy N; Contreras, Alejandro et al. (2006) A noncoding RNA is a potential marker of cell fate during mammary gland development. Proc Natl Acad Sci U S A 103:5781-6 |
| Sharp, Z Dave; Mancini, Maureen G; Hinojos, Cruz A et al. (2006) Estrogen-receptor-alpha exchange and chromatin dynamics are ligand- and domain-dependent. J Cell Sci 119:4101-16 |
| Medina, Daniel (2005) Mammary developmental fate and breast cancer risk. Endocr Relat Cancer 12:483-95 |
| Ginger, Melanie R; Rosen, Jeffrey M (2003) Pregnancy-induced changes in cell-fate in the mammary gland. Breast Cancer Res 5:192-7 |
| Stenoien, D L; Sen, S; Mancini, M A et al. (2003) Dynamic association of a tumor amplified kinase, Aurora-A, with the centrosome and mitotic spindle. Cell Motil Cytoskeleton 55:134-46 |
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