Nuclear localization and increased levels of transcription factor YB-1 in primary human breast cancers are associated with intrinsic MDR1 gene expression.
Nat Med
; 3(4): 447-50, 1997 Apr.
Article
em En
| MEDLINE
| ID: mdl-9095180
ABSTRACT
Breast cancers are either primarily resistant to chemotherapy (intrinsic resistance), or respond to chemotherapy but later recur with a multidrug-resistant phenotype because of overexpression of the multidrug transporter P-glycoprotein. The MDR1 gene encoding P-glycoprotein may be transcriptionally regulated by a Y-box transcription factor. We now report that, in multidrug-resistant MCF-7 breast cancer cells, nuclear localization of YB-1 is associated with MDR-1 gene expression. In drug-sensitive MCF-7 cells, however, YB-1 was localized to the cytoplasm. Regulated overexpression of YB-1 in drug-sensitive diploid breast epithelial cells induced MDR-1 gene expression and multidrug resistance. In 27 out of 27 untreated primary breast cancers, YB-1 protein was expressed in the cytoplasm although it was undetectable in normal breast tissue of these patients. In a subgroup of tumors (9/27), however, YB-1 was also localized to the nucleus and, in these cases, high levels of P-glycoprotein were present. These results show that in a subset of untreated primary breast cancers, nuclear localization of YB-1 protein is associated with intrinsic multidrug resistance. Our data show that YB-1 has an important role in controlling MDR1 gene transcription and this finding provides a basis for the analysis of molecular mechanisms responsible for intrinsic multidrug resistance in human breast cancer.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fatores de Transcrição
/
Neoplasias da Mama
/
Regulação Neoplásica da Expressão Gênica
/
Membro 1 da Subfamília B de Cassetes de Ligação de ATP
/
Resistência a Múltiplos Medicamentos
/
Proteínas Estimuladoras de Ligação a CCAAT
/
Proteínas de Ligação a DNA
Tipo de estudo:
Risk_factors_studies
Limite:
Adult
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Aged
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Female
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Humans
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Middle aged
Idioma:
En
Ano de publicação:
1997
Tipo de documento:
Article