Interplay between long non-coding RNAs and microRNAs in cancer

In the last decade non-coding RNAs (ncRNAs) have been extensively studied in several biological processes and human diseases including cancer. microRNAs (miRNAs) are the best well-known class of ncRNAs. miRNAs are small ncRNAs of around 23 nt and are crucial post-transcriptional regulators of protein coding genes. Recently, new classes of ncRNAs have been discovered, longer than miRNAs such as long intergenic non-coding RNAs (lincRNAs) and circular RNAs (circRNAs). These novel types of ncRNAs opened a very exciting field in biology, leading researchers to discover new relationships between miRNAs and long non-coding RNAs (lncRNAs) to control protein coding gene expression. One of this new discovery led to formulate the competing endogenous RNA (ceRNA) hypothesis, where a lncRNA acts as a sponge for miRNAs reducing their expression and causing the upregulation of miRNA targets. In this chapter we first discuss some recent discoveries in this field showing the mutual regulation of miRNAs, lncRNAs and protein coding genes in cancer, then we show the general approach for the study of ceRNAs and present with more details a recent computational approach that has been shown to be the most precise and promising.