Cancer progression is often aided by increased expression of particular genes called oncogenes. Although this is often associated with changes in DNA, Christine Mayr and David Bartel of the Whitehead Institute for Biomedical Research in Cambridge have shown that alterations to the messenger RNAs of several oncogenes can also contribute.
These alterations mostly occur as a result of alternative processing in the 3′UTR, an RNA region that doesn't encode protein. The processing involves the way that the end of an RNA strand is cut and the position at which a string of adenine bases is added, resulting in 3′UTRs of different lengths. Shorter than usual 3′UTRs make the mRNA more stable, typically allowing it to produce ten times the normal amount of the oncogene's protein. This overexpression is only partly explained by the loss of sites on the RNA that are recognized for silencing by microRNAs.