ERα/SP1 regulation of DNA polymerase α and related genes in breast cancer cells : mechanistic studies /
Estrogens, growth factors, and other mitogens induce proliferation of MCF-7 human breast cancer cells (Dickson 1988, 1991, 1995; Ethier 1995), and 17β-estradiol (E2) induced responses are accompanied by activation of the cell cycle and important metabolic genes. The classical mechanism of hormone-de...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2002.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=764789881&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Estrogens, growth factors, and other mitogens induce proliferation of MCF-7 human breast cancer cells (Dickson 1988, 1991, 1995; Ethier 1995), and 17β-estradiol (E2) induced responses are accompanied by activation of the cell cycle and important metabolic genes. The classical mechanism of hormone-dependent gene activation involves binding of the liganded hormone receptor to hormone responsive elements (HRE) in promoter regions of target genes. The bound receptor in turn recruits coactivators, chromatin remodelling proteins, and the transcriptional machinery necessary for gene expression. Our lab has elucidated an alternative DNA binding-independent mechanism of estrogen receptor (ER) action in which transactivation occurs by an interaction of the ligand-bound ERα with the transcription factor Sp1 bound to G or GC-rich motifs in promoters of E2 responsive genes (Krishnan, et al. 1994; Porter, et al. 1996; Duan, et al. 1998). DNA polymerase α is the major replicase in eukaryotic cells (Alama, et al. 1993; Burgers 1998) and thus an essential gene for their survival. Preliminary data indicated that DNA polymerase a is upregulated by E2 in MCF-7 breast cancer cells. We thus hypothesized that DNA polymerase α is activated by ERα in a DNA independent manner and demonstrated that hormonal regulation of this gene in breast cancer cells involves ERα/Sp1 interactions with a single GC-rich site (-106) upstream of the start site. We studied the interactions of ERα and Sp proteins in the context of GC-rich hormone responsive promoters using a novel in vitro footprinting technique that uses the viral CpG methylase SssI instead of nucleases to map binding of proteins to DNA (Kladde MP 1996; Kladde MP 1996). In addition, the chromatin immunoprecipitation (ChIP) assay was also developed for investigating the assembly of proteins bound to a given gene promoter at a given point in time. Preliminary results showed the importance of cell context, coactivator expression, and rapid exchange of transcription factors in protein binding to E2 responsive promoter regions. We also demonstrated that ERα/Sp1 complexes are associated with hormone-responsive GC-rich gene promoters within the nucleus of breast cancer cells. |
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| Item Description: | Vita. "Major Subject: Genetics". In title, numerals and symbols are used. |
| Physical Description: | xvi, 272 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 217-271). |