The long-term goal of the research in the Stampfer laboratory has been the development and characterization of a model system for the culture of human mammary epithelial cells (HMEC), in order to better understand how growth is controlled in normal HMEC and how these regulatory controls change as a result of immortal and malignant transformation. Dr. Stampfer has defined a number of phenotypic markers which suggest that carcinogen-treated HMEC first undergo a conditional immortalization event, and later, after overcoming a growth crisis, become fully immortalized. This latter process, which the principal investigator calls conversion, occurs when the cells have critically short telomeres. The proposed studies will focus on the mechanism of conversion, with the following questions being addressed.
Aim 1. What molecular events underlie the conversion process and how are they interrelated? Attempts will be made to determine if the phenotypic changes that occur during conversion (growth in the presence or absence of TGF beta, telomerase activity, regulation of CDKIs (cyclin-dependent kinase inhibitors) p57 and p27, and c-myc) are coordinately controlled, with particular focus on alterations in c-myc and p57 during GO growth arrest. Additionally, the role of p53 in conversion will be assessed, and a determination will be made whether viral oncogenes, which accelerate conversion, can be used as tools to elucidate the conversion process.
Aim 2. Can the conversion process be influenced by external conditions such as media composition? Aim 3. How do fully immortal cells maintain telomere length regulation. These studies will focus on the relationship among telomere length, telomerase activity and p57 expression under normal and perturbed (i.e. antisense telomerase RNA) activity. Additionally, the principal investigator will continue to collaborate with other investigators who wish to work with her cell lines.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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Chemical Pathology Study Section (CPA)
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Okano, Paul
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Lawrence Berkeley National Laboratory
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United States
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Garbe, James C; Vrba, Lukas; Sputova, Klara et al. (2014) Immortalization of normal human mammary epithelial cells in two steps by direct targeting of senescence barriers does not require gross genomic alterations. Cell Cycle 13:3423-35
Garbe, James C; Bhattacharya, Sanchita; Merchant, Batul et al. (2009) Molecular distinctions between stasis and telomere attrition senescence barriers shown by long-term culture of normal human mammary epithelial cells. Cancer Res 69:7557-68
Nijjar, Tarlochan; Bassett, Ekaterina; Garbe, James et al. (2005) Accumulation and altered localization of telomere-associated protein TRF2 in immortally transformed and tumor-derived human breast cells. Oncogene 24:3369-76
Stampfer, Martha R; Garbe, James; Nijjar, Tarlochan et al. (2003) Loss of p53 function accelerates acquisition of telomerase activity in indefinite lifespan human mammary epithelial cell lines. Oncogene 22:5238-51
Stampfer, Martha R; Yaswen, Paul (2003) Human epithelial cell immortalization as a step in carcinogenesis. Cancer Lett 194:199-208
Yaswen, P; Stampfer, M R (2001) Epigenetic changes accompanying human mammary epithelial cell immortalization. J Mammary Gland Biol Neoplasia 6:223-34
Stampfer, M R; Garbe, J; Levine, G et al. (2001) Expression of the telomerase catalytic subunit, hTERT, induces resistance to transforming growth factor beta growth inhibition in p16INK4A(-) human mammary epithelial cells. Proc Natl Acad Sci U S A 98:4498-503
Nonet, G H; Stampfer, M R; Chin, K et al. (2001) The ZNF217 gene amplified in breast cancers promotes immortalization of human mammary epithelial cells. Cancer Res 61:1250-4
Stampfer, M R; Yaswen, P (2000) Culture models of human mammary epithelial cell transformation. J Mammary Gland Biol Neoplasia 5:365-78
Kim, D W; Sovak, M A; Zanieski, G et al. (2000) Activation of NF-kappaB/Rel occurs early during neoplastic transformation of mammary cells. Carcinogenesis 21:871-9

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