The functional -443T/C osteopontin promoter polymorphism influences osteopontin gene expression in melanoma cells via binding of c-Myb transcription factor.
Mol Carcinog
; 48(1): 14-23, 2009 Jan.
Article
em En
| MEDLINE
| ID: mdl-18459127
ABSTRACT
In the present report, the possible role of a recently described functional polymorphism of the osteopontin (OPN) promoter at position -443 (-443T/C) for OPN expression in melanoma cells was addressed. As shown by real-time PCR analysis, melanoma metastases that were homozygous for the -443C allele expressed significantly higher levels of OPN mRNA compared with those that were either heterozygous (-443T/C) or homozygous for the -443T allele. In line with this, immunoblotting showed significantly enhanced baseline and bFGF-induced OPN protein expression in melanoma cell lines which were homozygous for the -443C allele, compared with cell lines with other allelic variants. Similar results were obtained in in vitro luciferase assays. Chromatin immunoprecipitation (ChIP) demonstrated binding of c-Myb to the -443 OPN promoter region, and binding could significantly be enhanced after bFGF stimulation. Moreover, as shown by electrophoretic mobility shift assays (EMSA), recombinant DNA-binding domain of c-Myb bound in a sequence-specific manner to this region. Finally, the role of c-Myb for OPN gene regulation via binding to the -443 promoter region could be further substantiated by ectopic overexpression of c-Myb in melanoma cells, using different reporter gene constructs. Taken together, it is demonstrated that the -443 promoter region exerts influence on OPN gene expression in melanoma cells, and differential binding of c-Myb transcription factor appears to play a major role in this process. These findings might be a feasible explanation for different OPN expression levels in metastatic tumors and may also have prognostic and therapeutic relevance.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Polimorfismo Genético
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Regulação Neoplásica da Expressão Gênica
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Regiões Promotoras Genéticas
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Proteínas Proto-Oncogênicas c-myb
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Osteopontina
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Melanoma
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Ano de publicação:
2009
Tipo de documento:
Article