Inhibition of transcription factor binding to the HER2 promoter by triplex-forming oligodeoxyribonucleotides.
We have identified a 28-bp homopurine/homopyrimidine sequence capable of triple helix (triplex) formation with G+T-rich oligodeoxyribonucleotides (oligos) within the critical proximal promoter of the HER2/neu/c-erbB2 (HER2) proto-oncogene. To investigate the possible therapeutic potential of triplex-forming oligos in HER2 overexpressing breast cancers, we have studied the ability of triplex formation to compete with and to inhibit the binding of a transcription factor to its consensus sequence at an adjacent site. Competition binding assays demonstrate that a triplex-forming oligo can inhibit transcription factor binding in a sequence-specific manner. Moreover, we find that the addition of both nucleotide and non-nucleotide 'tails' to triplex-forming oligos do not confer any enhancement of binding affinity, but provide additional inhibition of transcription factor binding, potentially by steric hindrance.
Cancer Research Institute, University of California at San Francisco 94143.
S B
SB
Noonberg
G K
GK
Scott
C A
CA
Hunt
M E
ME
Hogan
C C
CC
Benz
D001483:Base Sequence; D001667:Binding, Competitive; D001943:Breast Neoplasms; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D000090063:Proto-Oncogene Mas; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics*; D015682:Retroviridae Proteins, Oncogenic; D014157:Transcription Factors / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D000090063:Proto-Oncogene Mas; D018719:Erb-b2 Receptor Tyrosine Kinases; D015682:Retroviridae Proteins, Oncogenic; D014157:Transcription Factors; C000715470:MAS1 protein, human; C062022:v-Spi-1 protein, Friend spleen focus-forming virus