MicroRNAs, ultraconserved genes and colorectal cancers

In this review we present some recent advances in understanding the roles of non-coding RNAs, including microRNAs and ultraconserved genes, in colorectal cancer and the way these advances can be translated for better cure of patients. MicroRNAs are a class of small RNAs that do not code for proteins and yet function as gene regulators. The deregulation of microRNA expression is involved in the initiation, progression, and dissemination of any type of human tumor. The underlying mechanisms of microRNA deregulation in human cancers are just starting to be understood. Germline and somatic mutations in microRNAs or polymorphisms in the messenger protein-coding RNAs targeted by microRNAs may also contribute to the tumor phenotype. Profiling microRNAs by various methods has identified signatures associated with the diagnosis, staging, progression, and prognosis of human colorectal cancers. Consequently, miRNAs have potential as diagnostic biomarkers and therapeutic targets in colorectal cancers. Ultraconserved genes represent a recently identified class of transcripts, mainly non-coding, that are highly conserved during evolution and can regulate miRNAs by direct interaction. Fingerprints of ultraconserved genes expression can classify cancers, including colorectal cancers, and ultraconserved genes may be involved in metastasis. Thus, having a clearer understanding of the mechanisms involved in the deregulation of non-coding RNAs in colorectal cancers is expected to contribute greatly to the development of new microRNA-based strategies for the diagnosis and treatment of patients.