MicroRNAs as Drugs and Drug Targets in Cancer

MicroRNAs (miRNAs) are evolutionarily conserved single-stranded RNAs of 19-24 nucleotides. These small RNAs do not code for proteins, but interfere with the transcription and translation of protein-coding genes. Studies in the last decade identified aberrant miRNA expression in many human diseases, and clearly showed a key involvement of miRNAs in the disease phenotype. MiRNAs have been experimentally modulated to promote or reverse a disease phenotype in vitro and in vivo. More recently, the first clinical trial using SPC3649, a miR-122 antagonist, has demonstrated the effectiveness and safety of miRNA-based therapeutics. This research indicates that miRNAs could be ideal candidates as therapeutic agents or drug targets. In this chapter we briefly introduce miRNAs and their involvement in cancer and other diseases, followed by discussion of the rationale for miRNA therapeutics and a detailed summarization of the currently available tools to restore or block miRNA function.