The estrogen receptor (ER) plays an important role in maintaining cellular homeostasis; however, the ER also plays a critical role in formation and growth of estrogen-dependent mammary and endometrial cancers which are major health problems for women. Preliminary studies in this laboratory have demonstrated that E2-induced transactivation of several genes in breast cancer cells involves interaction of an Sp1/ER complex with GC-rich motifs. Therefore, we hypothesize that interaction of the Sp1/ER transcription factor complex with 5'-(promoter) GC-rich sequences plays an important role in hormone-induced expression of diverse genes, including those involved in DNA synthesis. Other factors and enhancer sequences may modulate this response, and Aims 1-4 will therefore extensively investigate the molecular mechanisms of Sp1/ER- induced expression of several target genes containing GC-rich 5'- promoter regions.
Aim 1 will investigate the requirements for formation and function of Sp1/ER-DNA complexes using Sp1(n)xERE(1/2) 5'-promoter sequences and oligonucleotides with variable DNA binding sites and intervening oligonucleotides; the interaction of Sp1/ER with other cellular co-activators including ERAP-140, ERAP-160/SRC-1, RIP 140 and CBP/p300 will also be investigated. Preliminary results have shown that ER and Sp1 proteins physically interact and E2-induced gene expression can be observed through promoters containing only GC-rich Sp1 binding sites. Therefore, Aim 2 will investigate the functional synergy and physical interactions of Sp1 and ER proteins in which transactivation is independent of ER-DNA interactions. The proposed studies will determine domain-specific interactions between Sp1 and ER proteins, ligand (antiestrogen vs estrogen)-dependent differences in mechanisms of transactivation and the role of co-activators in the induction process.
Aim will focus on the role of Sp1 and GC-rich sequences in the mechanism of E2-induced IGF receptor, MUC-1 and ornithine decarboxylase gene expression. Several hormone-induced genes involved in DNA synthesis, including dihydrofolate reductase, thymidine kinase, thymilidate synthase and adenosine deaminase, contain GC-rich regions in their 5'-proximal promoter regions, and Aim 4 will determine the role of Sp1/ER complexes in mediating induction of these genes. The proposed research will investigate the molecular mechanism which regulate several E2-responsive genes that play an important role in proliferation of breast cancer cells. These results will ultimately facilitate design of chemotherapeutic approaches which target specific genes.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA076636-03
Application #
6137651
Study Section
Biochemical Endocrinology Study Section (BCE)
Program Officer
Mietz, Judy
Project Start
1998-01-01
Project End
2001-12-31
Budget Start
2000-01-01
Budget End
2000-12-31
Support Year
3
Fiscal Year
2000
Total Cost
$130,893
Indirect Cost
Name
Texas A&M University
Department
Veterinary Sciences
Type
Schools of Veterinary Medicine
DUNS #
047006379
City
College Station
State
TX
Country
United States
Zip Code
77845
Khan, Shaheen; Barhoumi, Rola; Burghardt, Robert et al. (2006) Molecular mechanism of inhibitory aryl hydrocarbon receptor-estrogen receptor/Sp1 cross talk in breast cancer cells. Mol Endocrinol 20:2199-214
Stoner, Matthew; Wormke, Mark; Saville, Brad et al. (2004) Estrogen regulation of vascular endothelial growth factor gene expression in ZR-75 breast cancer cells through interaction of estrogen receptor alpha and SP proteins. Oncogene 23:1052-63
Khan, Shaheen; Abdelrahim, Maen; Samudio, Ismael et al. (2003) Estrogen receptor/Sp1 complexes are required for induction of cad gene expression by 17beta-estradiol in breast cancer cells. Endocrinology 144:2325-35
Vyhlidal, C; Li, X; Safe, S (2002) Estrogen regulation of transferrin gene expression in MCF-7 human breast cancer cells. J Mol Endocrinol 29:305-17
Saville, Bradley; Poukka, Hetti; Wormke, Mark et al. (2002) Cooperative coactivation of estrogen receptor alpha in ZR-75 human breast cancer cells by SNURF and TATA-binding protein. J Biol Chem 277:2485-97
Samudio, I; Vyhlidal, C; Wang, F et al. (2001) Transcriptional activation of deoxyribonucleic acid polymerase alpha gene expression in MCF-7 cells by 17 beta-estradiol. Endocrinology 142:1000-8
Castro-Rivera, E; Samudio, I; Safe, S (2001) Estrogen regulation of cyclin D1 gene expression in ZR-75 breast cancer cells involves multiple enhancer elements. J Biol Chem 276:30853-61
Wang, F; Samudio, I; Safe, S (2001) Transcriptional activation of rat creatine kinase B by 17beta-estradiol in MCF-7 cells involves an estrogen responsive element and GC-rich sites. J Cell Biochem 84:156-72
Safe, S (2001) Transcriptional activation of genes by 17 beta-estradiol through estrogen receptor-Sp1 interactions. Vitam Horm 62:231-52
Xie, W; Duan, R; Chen, I et al. (2000) Transcriptional activation of thymidylate synthase by 17beta-estradiol in MCF-7 human breast cancer cells. Endocrinology 141:2439-49

Showing the most recent 10 out of 18 publications