Inhibition of aromatase expression by a psoralen-linked triplex-forming oligonucleotide targeted to a coding sequence

• Published in: FEBS letters 1995-09, Vol.372 (2), p.222-228
• Main Authors: Macaulay, V.M., Bates, P.J., McLean, M.J., Rowlands, M.G., Jenkins, T.C., Ashworth, A., Neidle, S.
• Format: Article
• Language: English
• Subjects: Aromatase; Aromatase - biosynthesis; Base Sequence; Binding Sites; Ficusin - metabolism; Humans; Molecular Sequence Data; Oligonucleotides - pharmacology; Protein Synthesis Inhibitors - pharmacology; Psoralen; Triplex formation; Tumor Cells, Cultured
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(95)00987-K

The cytochrome P450 enzyme aromatase (P450arom) is an important target in breast cancer treatment. We have designed a 20-base pyrimidine oligodeoxynucleotide (ODN) which forms a sequence-specific triple helix (triplex) with a purine-rich tract in the P450arom coding sequence. The psoralen-linked ODN (Pso20T) formed photo-induced cross-linked products with target double-stranded DNA. Cross-linked adducts formed in vitro between ODNs and P450arom expression constructs were used to transfect COS and human MCF-7 breast cancer cells. Levels of aromatase transcripts and enzyme activity were significantly lower in cultures transfected with Pso20T-treated cDNA relative to controls. Pso20T had a lesser inhibitory effect on aromatase expression from a mutant P450arom construct, consistent with predicted effects of the mutations on triplex formation. These results are compatible with triplex-mediated interruption of transcription within intact cells.