Short interfering RNA (siRNA) as a novel therapeutic.

1. RNA interference (RNAi) is a robust method of post-transcriptional silencing of genes using double-stranded RNA (dsRNA) with sequence homology driven specificity. The dsRNA can be between 21 and 23 nucleotides long: this is converted to small interfering RNA (siRNA), which then mediates gene silencing by degradation/blocking of translation of the target mRNA. 2. RNA interference provides a simple, fast and cost-effective alternative to existing gene targeting approaches both in vitro and in vivo. The discovery of siRNAs that cause RNAi in mammalian cells opened the door to the therapeutic use of siRNAs. Highly intense research efforts are now aimed at developing siRNAs for therapeutic purposes. 3. Recent advances in the design and delivery of targeting molecules now allow efficient and highly specific gene silencing in mammalian systems. Synthetic siRNA libraries targeting thousands of mammalian genes are publicly available for high-throughput genetic screens for target discovery and validation. Recent studies have demonstrated the clinical potential of aptly designed siRNAs in various types of viral infections, cancer and renal and neurodegenerative disorders. 4. The present review provides insight into the novel therapeutic strategies of siRNA technology, which is the latest development in nucleic acid-based tools for knocking down gene expression, and its potential for silencing genes associated with various human diseases.