Physiological and Pathological Functions of Mammalian MicroRNAs

MicroRNAs (miRNAs) are 19 to 26-nucleotide RNAs that regulate gene expression. More than 2000 novel human miRNA genes have been identified, and new ones are continuously being discovered. Recent computational methods indicate that up to 92% of human genes may be regulated by miRNA. In this article, we discuss recent progress in miRNA biology and their roles in human disease pathogenesis, particularly in cancer, as well as opportunities and challenges of miRNA-based therapies.