title: Tumor suppressor p53 is required to modulate BRCA1 expression.
abstract: Individuals carrying mutations in BRCA1 or p53 genes are predisposed to a variety of cancers, and both tumor suppressor genes have been implicated in DNA damage response pathways. We have analyzed a possible functional link between p53 and BRCA1 genes. Here we show that BRCA1 expression levels are down-regulated in response to p53 induction in cells that undergo either growth arrest, senescence, or apoptosis. Physiological stimuli, such as exposure to DNA-damaging agents, also result in negative regulation of BRCA1 levels in a p53-dependent manner prior to causing cell cycle arrest. Nuclear run-on experiments and luciferase reporter assays demonstrate that the changes in BRCA1 expression are mainly due to transcriptional repression induced by p53. In conclusion, the data show that BRCA1 expression levels are controlled by the presence and activity of wild-type p53 and suggest the existence of an intracellular p53/BRCA1 pathway in the response of cells to stress conditions.
authors.affiliation: Department of Medicine, Harvard Medical School and Beth Israel Deaconess Medical Center, Harvard Institutes of Medicine, Boston, Massachusetts 02115, USA.
authors.forename: P
authors.initials: P
authors.lastname: Arizti
authors.forename: L
authors.initials: L
authors.lastname: Fang
authors.forename: I
authors.initials: I
authors.lastname: Park
authors.forename: Y
authors.initials: Y
authors.lastname: Yin
authors.forename: E
authors.initials: E
authors.lastname: Solomon
authors.forename: T
authors.initials: T
authors.lastname: Ouchi
authors.forename: S A
authors.initials: SA
authors.lastname: Aaronson
authors.forename: S W
authors.initials: SW
authors.lastname: Lee
mesh_terms: D000818:Animals; D019313:BRCA1 Protein / Q000235:genetics* / Q000378:metabolism; D002453:Cell Cycle; D002478:Cells, Cultured; D004249:DNA Damage; D015536:Down-Regulation; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006801:Humans; D051379:Mice; D009154:Mutation; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
chemical_list: D019313:BRCA1 Protein; D012333:RNA, Messenger; D012097:Repressor Proteins; D016159:Tumor Suppressor Protein p53