Silencing of gene expression by targeted DNA methylation: concepts and approaches.

Targeted DNA methylation is a novel and attractive approach for stable silencing of gene expression by epigenetic mechanisms. The potential applications of this concept include cancer treatment, treatment of viral infections and, in general, treatment of any disease that could be attenuated by the stable repression of known target genes. We review the literature on targeted DNA methylation and gene silencing, summarize the achievements and the challenges that remain, and discuss technical issues critical for this approach.