Circular RNAs: the next level of gene regulation

Gene regulation is a highly complex process involving the presence and participation of many molecules and complexes that regulate gene expression in the genome, which occurs in a precise and coordinated way. Among all these regulatory molecules, the circular RNAs (circRNAs) are the most novel and peculiar family of noncoding RNAs (ncRNAs) as they have a circular structure, are very specific on their expression, highly conserved, and highly resistant to degradation. These molecules have been described in recent years as excellent disease markers and as potential therapeutic targets. In this review, we focused on general characteristics and on the evolution of the circRNAs, as well as on their biological functions, emphasizing on their participation in the formation of brain tumors.