Specific inhibition of c-fos proto-oncogene expression by triple-helix-forming oligonucleotides

✍ Scribed by Y. Lavrovsky; V. Mastyugin; R. A. Stoltz; N. G. Abraham

• Book ID: 102655842
• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 770 KB
• Volume: 61
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/(sici)1097-4644(19960501)61:2<301::aid-jcb13>3.0.co;2-o

✦ Synopsis

The promoter region of the c-fos oncogene 5' flanking sequence contains enhancer elements crucial for binding nuclear factors that regulate transcription following cell proliferation and differentiation. Single-stranded deoxyoligonucleotides were chosen for modulation of c-fos protooncogene expression because of their high-affinity binding to specific nucleotide sequences. We designed two oligonucleotides that form a triple-helix complex on the retinoblastoma gene product-responsible element of the c-fos oncogene.

Modification of the DNA triplex with dimethyl sulfate and affinity cleaving assays demonstrate that the predicted oligonucleotides form a DNA triplex structure with the c-fos promoter in a sequence-specific manner. Tumorigenic and non-tumorigenic fibroblasts were transiently transfected with fos-CAT plasmid modified with alkylating triplex-forming oligonucleotide reagents. A dramatic depression of CAT activity was found when the cross-linked triple helix complex at the retinoblastoma gene product-related site of the c-fos promoter was used.

These experiments suggest that transcription of individual genes can be selectively modulated in cell culture by sequence specific triplex formation in regulatory enhancer sequences.