A-to-I RNA editing as a tuner of noncoding RNAs in cancer

Recent advancement in RNA technology and computation biology shows the abundance and impact of RNA editing at the genome-wide level. Of RNA editing events, Adenosine-to-inosine (A-to-I) RNA editing is one of the most frequent types of RNA editing catalyzed by ADAR proteins. Indeed, A-to-I RNA editing occurs at the various coding and noncoding regions, triggering abnormal signaling pathways involved in cancer pathogenesis. Noncoding RNAs such as microRNA and long noncoding RNA have emerged as key regulators of pathways in cancer. The RNA editing including A-to-I editing is enriched in noncoding regions because of the abundance of noncoding RNAs accounting for 99% of total transcripts in the human genome. The effects of A-to-I editing in coding genes have been investigated and reported. However, those in noncoding RNAs have been less known in spite of the high frequency of editing events in noncoding regions. In this review, we will briefly discuss current findings and potential directions of A-to-I RNA editing research of noncoding RNAs and cancer. We will also introduce the concept of A-to-I editing, ADAR proteins, RNA editing technologies and databases.