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.
Noonberg
S B
SB
Cancer Research Institute, University of California at San Francisco 94143.
Scott
G K
GK
Hunt
C A
CA
Hogan
M E
ME
Benz
C C
CC
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