Activating gene expression in mammalian cells with promoter-targeted duplex RNAs

The ability to selectively activate or inhibit gene expression is fundamental to understanding complex cellular systems anddeveloping therapeutics. Recent studies have demonstrated that duplex RNAs complementary to promoters within chromosomalDNA are potent gene silencing agents in mammalian cells. Here we report that chromosome-targeted RNAs also activate geneexpression. We have identified multiple duplex RNAs complementary to the progesterone receptor (PR) promoter that increaseexpression of PR protein and RNA after transfection into cultured T47D or MCF7 human breast cancer cells. Upregulation of PRprotein reduced expression of the downstream gene encoding cyclooygenase 2 but did not change concentrations of estrogenreceptor, which demonstrates that activating RNAs can predictably manipulate physiologically relevant cellular pathways.Activation decreased over time and was sequence specific. Chromatin immunoprecipitation assays indicated that activation isaccompanied by reduced acetylation at histones H3K9 and H3K14 and by increased di- and trimethylation at histone H3K4.These data show that, like proteins, hormones and small molecules, small duplex RNAs interact at promoters and can activate orrepress gene expression.Duplex RNAs are powerful tools for silencing gene expression and arebeing evaluated for therapeutic efficacy in clinical trials