Profiling of miRNA expression and prediction of target genes.

MicroRNAs (miRNAs) represent a new class of small noncoding RNAs expressed in plants and animals. They are responsible for the regulation of up to 30% of human genes, thus underlying their influence on almost all cellular pathways. Recent studies have shown miRNAs to be differentially expressed in cancers. Furthermore, several miRNAs are associated with fragile sites, preferential sites of translation, deletion and amplification that are often altered in cancers. However, despite the progress in identifying miRNA genes, knowledge about their functions and specific target genes is still limited. This chapter highlights the technical advances in miRNA gene profiling and discusses the limitations of target prediction programs and the necessity of defining the roles that govern miRNA specificity and target discrimination in vivo.