title: Yin Yang 1 positively regulates BRCA1 and inhibits mammary cancer formation.
abstract: Expression of the breast cancer-associated gene 1 (BRCA1) in sporadic breast cancers is usually reduced, yet the underlying mechanisms remains elusive. To identify factors that are responsible for reduced BRCA1 expression, we screened 92 known transcription factors for their ability to regulate expression of BRCA1. Among several potential regulators, the Gli-Krueppel-related transcription factor Yin Yang 1 (YY1) showed the most dramatic transactivation of the BRCA1 promoter. YY1 binds to the promoter of BRCA1, and its overexpression resulted in increased expression of BRCA1 and a number of BRCA1 downstream genes. We further showed that overexpression of YY1 in cancer cells inhibited cell proliferation, foci formation and tumor growth in nude mice. To assess the clinical relevance between YY1 and BRCA1, we studied expression of YY1 and BRCA1 from human breast cancer samples and tissue arrays, and detected a significant positive correlation between the level of YY1 and BRCA1 expression in these cancers. Taken together, these findings suggest that YY1 is a key regulator of BRCA1 expression and may be causally linked to the molecular etiology of human breast cancer.
authors.affiliation: Genetics of Development and Disease Branch, 10/9N105, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: M-H
authors.initials: MH
authors.lastname: Lee
authors.forename: T
authors.initials: T
authors.lastname: Lahusen
authors.forename: R-H
authors.initials: RH
authors.lastname: Wang
authors.forename: C
authors.initials: C
authors.lastname: Xiao
authors.forename: X
authors.initials: X
authors.lastname: Xu
authors.forename: Y-S
authors.initials: YS
authors.lastname: Hwang
authors.forename: W-W
authors.initials: WW
authors.lastname: He
authors.forename: Y
authors.initials: Y
authors.lastname: Shi
authors.forename: C-X
authors.initials: CX
authors.lastname: Deng
mesh_terms: D000818:Animals; D019313:BRCA1 Protein / Q000032:analysis / Q000235:genetics*; D001940:Breast / Q000196:embryology; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology / Q000517:prevention & control; D002453:Cell Cycle; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000473:pathology; D005260:Female; D019398:Genes, BRCA1; D006801:Humans; D051379:Mice; D011401:Promoter Regions, Genetic; D025521:Tumor Suppressor Proteins / Q000502:physiology*; D050986:YY1 Transcription Factor / Q000032:analysis / Q000502:physiology*
chemical_list: D019313:BRCA1 Protein; C492913:BRCA1 protein, human; D025521:Tumor Suppressor Proteins; D050986:YY1 Transcription Factor; C494698:YY1 protein, human