1. Chromatin structure of the regulatory regions of pS2 and cathepsin D genes in hormone-dependent and -independent breast cancer cell lines
- Author
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Monserrat Solanas, Patrick Augereau, Françoise Vignon, Hélène Richard-Foy, Henri Rochefort, Catherine Chailleux, and Claire Giamarchi
- Subjects
Cancer Research ,Neoplasms, Hormone-Dependent ,Protein Conformation ,Molecular Sequence Data ,Estrogen receptor ,Breast Neoplasms ,Biology ,Regulatory Sequences, Nucleic Acid ,Cathepsin D ,Genetics ,Tumor Cells, Cultured ,Humans ,RNA, Messenger ,Insulin-Like Growth Factor I ,skin and connective tissue diseases ,Promoter Regions, Genetic ,Molecular Biology ,Gene ,DNA Primers ,Base Sequence ,Tumor Suppressor Proteins ,Estrogen Antagonists ,Proteins ,Promoter ,Transfection ,Chromatin ,Cell biology ,Cell culture ,Regulatory sequence ,Trefoil Factor-1 ,Hypersensitive site ,hormones, hormone substitutes, and hormone antagonists - Abstract
We have compared the DNase I hypersensitivity of the regulatory region of two estrogen-regulated genes, pS2 and cathepsin D in hormone-dependent and -independent breast carcinoma cell lines. This strategy allowed the identification of two important control regions, one in pS2 and the other in cathepsin D genes. In the hormone-dependent MCF7 cell line, within the pS2 gene 5'-flanking region, we detected two major DNase I hypersensitive sites, induced by estrogens and/or IGFI: pS2-HS1, located in the proximal promoter and pS2-HS4, located -10.5 Kb from the CAP site, within a region that has not been cloned. The presence of these two DNase I hypersensitive sites correlates with pS2 expression. Interestingly in MCF7 cells, estrogens and IGFI induced indistinguishable chromatin structural changes over the pS2 regulatory region, suggesting that the two transduction-pathways converge to a unique chromatin target. In two cell lines that do not express pS2, MDA MB 231, a hormone-independent cell line that lacks the estrogen receptor alpha, and HE5, a cell line derived from MDA MB 231 by transfection that expresses estrogen receptor alpha, there was only one hormone-independent DNase I hypersensitive site. This site, pS2-HS2, was located immediately upstream of pS2-HS1. In MCF7 cells, two major DNase I hypersensitive sites were present in the 5'-flanking sequences of the cathepsin D gene, which is regulated by estrogens in these cells. These sites, catD-HS2 and catD-HS3, located at positions -2.3 Kb and -3.45 Kb, respectively, were both hormone-independent. A much weaker site, catD-HS1, covered the proximal promoter. In MDA MB 231 cells, that express cathepsin D constitutively, we detected an additional strong hormone-independent DNase I hypersensitive site, catD-HS4, located at position -4.3 Kb. This region might control the constitutive over-expression of cathepsin D in hormone-independent breast cancer cells. All together, these data demonstrate that a local reorganization of the chromatin structure over pS2 and cathepsin D promoters accompanies the establishment of the hormone-independent phenotype of the cells.
- Published
- 1999