Non-coding RNAs in Colorectal Cancer

Markus Kaller, Heiko Hermeking

Ondrej Slaby, George A. Calin

The epithelial-mesenchymal-transition (EMT) represents a morphogenetic program involved in developmental processes such as gastrulation and neural crest formation. The EMT program is co-opted by epithelial tumor cells and endows them with features necessary for spreading to distant sites, such as invasion, migration, apoptosis resistance and stemness. Thereby, EMT facilitates metastasis formation and therapy resistance. A growing number of transcription factors has been implicated in the regulation of EMT. These include EMT-inducing transcription factors (EMT-TFs), the most prominent being SNAIL, SLUG, ZEB1, ZEB2 and TWIST, and negative regulators of EMT, such as p53. Furthermore, a growing number of microRNAs, such as members of the miR-200 and miR-34 family, have been characterized as negative regulators of EMT. EMT-TFs and microRNAs, such as ZEB1/2 and miR-200 or SNAIL and miR-34, are often engaged in double-negative feedback loops forming bistable switches controlling the transitions from epithelial to the mesenchymal cell states. Within this chapter, we will provide a comprehensive overview over the transcription factors and microRNAs that have been implicated in the regulation of EMT in colorectal cancer. Furthermore, we will highlight the regulatory connections between EMT-TFs and miRNAs to illustrate common principles of their interaction that regulate EMTs.