TGFbeta is a potent inhibitor of cell growth. TGFbeta elicits its effects on cells by activation of specific cell surface ser/thr kinase receptors. The TGFbeta Receptor Type (TbetaRII) is an essential part of the TGFbeta signaling pathway. Recent histochemical studies reveal of loss of (TbetaRII) expression in invasive breast cancer. We have shown that the early passage breast adenocarcinoma cell line MCF-7 cells are TGFbeta sensitive and non-tumorigenic. Late passage MCF-7 cells have lost their ability to express this important signaling component of negative autocrine regulation. These cells are insensitive to TGFbeta's effects on growth and are tumorigenic in athymic nude mice. Our experiments indicate that naturally occurring differences in the level of TbetaRII expression can lead to differences in tumorigenetic potential. We show that the expression of (TbetaRII) in the MCF-7 late passage cells is repressed at the level of transcription due to inadequate levels of the Sp1 transcription factor. Therefore, these cells represent an ideal model system for examining a non-mutational mechanism of re-expression of this important tumor suppressor activity. These studies may enable the identification of targets for manipulation of (TbetaRII) expression, which could lead to development of agents for prevention as well as treatment of breast cancer.
The specific aims of this project are: 1. Determine the mechanism responsible for the differential levels of Sp1 in MCF-7L and MCF-7E cells. 2. Determine the role of AP1 or CRE in TbetaRII expression in MCF-7E versus MCF-7L cells. 3. Determine the specificity of the action of Sp1 on the TbetaRII promoter compared to other Sp1 responsive genes.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29CA079840-02
Application #
6124654
Study Section
Metabolic Pathology Study Section (MEP)
Program Officer
Freeman, Colette S
Project Start
1998-12-07
Project End
2003-11-30
Budget Start
1999-12-01
Budget End
2000-11-30
Support Year
2
Fiscal Year
2000
Total Cost
$95,806
Indirect Cost
Name
University of Toledo
Department
Biochemistry
Type
Schools of Medicine
DUNS #
807418939
City
Toledo
State
OH
Country
United States
Zip Code
43614