title: Estrogen regulates the association of intermediate filament proteins with nuclear DNA in human breast cancer cells.
abstract: In a previous study we showed that the levels of the intermediate filament proteins, cytokeratins 8, 18, and 19, in the nuclear matrix-intermediate filament (NM-IF) fraction from the hormone-dependent and estrogen receptor (ER)-positive human breast cancer cell line T-47D5 were regulated by estrogens. In contrast, estrogens did not regulate the cytokeratins in the NM-IF fraction of the hormone-independent and ER-positive cell line, T5-PRF. In this study, human breast cancer cells were treated with cis-diamminedichloroplatinum to cross-link protein to nuclear DNA in situ, and proteins bound to DNA were isolated. We show that cytokeratins 8, 18, and 19 of T-47D5 and T5-PRF were associated with nuclear DNA in situ. The levels of the cytokeratins 8, 18, and 19 bound to nuclear DNA or associated with the cytoskeleton of T-47D5 human breast cancer cells decreased when estrogens were depleted or the pure antiestrogen ICI 164,384 was added. In contrast, the cytokeratin levels associated with nuclear DNA or cytoskeleton were not significantly affected by estrogen withdrawal or antiestrogen administration in T5-PRF cells. These observations suggest that estrogen regulates the organization of nuclear DNA by rearrangement of the cytokeratin filament network in hormone-dependent, ER-positive human breast cancer cells and that this regulation is lost in hormone-independent, ER-positive breast cancer cells.
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba R3E OW3, Canada.
authors.forename: V A
authors.initials: VA
authors.lastname: Spencer
authors.forename: A S
authors.initials: AS
authors.lastname: Coutts
authors.forename: S K
authors.initials: SK
authors.lastname: Samuel
authors.forename: L C
authors.initials: LC
authors.lastname: Murphy
authors.forename: J R
authors.initials: JR
authors.lastname: Davie
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002467:Cell Nucleus / Q000378:metabolism*; D002945:Cisplatin / Q000378:metabolism; D018736:DNA Adducts / Q000378:metabolism; D004273:DNA, Neoplasm / Q000378:metabolism*; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology*; D006801:Humans; D007381:Intermediate Filament Proteins / Q000378:metabolism*; D007633:Keratins / Q000378:metabolism; D053284:Polyunsaturated Alkamides; D014407:Tumor Cells, Cultured
chemical_list: D018736:DNA Adducts; D004273:DNA, Neoplasm; D004965:Estrogen Antagonists; D004967:Estrogens; D007381:Intermediate Filament Proteins; D053284:Polyunsaturated Alkamides; C057270:cisplatin-DNA adduct; D004958:Estradiol; D007633:Keratins; C051781:ICI 164384; D002945:Cisplatin